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Purpose: To study the potential of viscoelastic parameters such as liver stiffness, loss tangent (marker of viscous properties) and viscoelastic dispersion to detect hepatic inflammation by in-vivo and ex-vivo MR elastography (MRE) at low and high vibration frequencies., Methods: 15 patients scheduled for liver tumor resection surgery were prospectively enrolled in this IRB-approved study and underwent multifrequency in-vivo MRE (30-60Hz) at 1.5-T prior to surgery. Immediately after liver resection, tumor-free tissue specimens were examined with ex-vivo MRE (0.8-2.8 kHz) at 0.5-T and histopathologic analysis including NAFLD activity score (NAS) and inflammation score (I-score) as sum of histological sub-features of inflammation., Results: In-vivo, in regions where tissue samples were obtained, the loss tangent correlated with the I-score (R = 0.728; p = 0.002) and c-dispersion (stiffness dispersion over frequency) correlated with lobular inflammation (R = -0.559; p = 0.030). In a subgroup of patients without prior chemotherapy, c-dispersion correlated with I-score also in the whole liver (R = -0.682; p = 0.043). ROC analysis of the loss tangent for predicting the I-score showed a high AUC for I ≥ 1 (0.944; p = 0.021), I ≥ 2 (0.804; p = 0.049) and I ≥ 3 (0.944; p = 0.021). Ex-vivo MRE was not sensitive to inflammation, whereas strong correlations were observed between fibrosis and stiffness (R = 0.589; p = 0.021), penetration rate (R = 0.589; p = 0.021), loss tangent (R = -0.629; p = 0.012), and viscoelastic model parameters (spring-pot powerlaw exponent, R = -0.528; p = 0.043; spring-pot shear modulus, R = 0.589; p = 0.021)., Conclusion: Our results suggest that c-dispersion of the liver is sensitive to inflammation when measured in-vivo in the low dynamic range (30-60Hz), while at higher frequencies (0.8-2.8 kHz) viscoelastic parameters are dominated by fibrosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Ascaris is one of the most widespread helminth infections, leading to chronic morbidity in humans and considerable economic losses in pig farming. In addition, pigs are an important reservoir for the zoonotic salmonellosis , where pigs can serve as asymptomatic carriers. Here, we investigated the impact of an ongoing Ascaris infection on the immune response to Salmonella in pigs. We observed higher bacterial burdens in experimentally coinfected pigs compared to pigs infected with Salmonella alone. The impaired control of Salmonella in the coinfected pigs was associated with repressed interferon gamma responses in the small intestine and with the alternative activation of gut macrophages evident in elevated CD206 expression. Ascaris single and coinfection were associated with a rise of CD4 - CD8α + FoxP3 + Treg in the lymph nodes draining the small intestine and liver. In addition, macrophages from coinfected pigs showed enhanced susceptibility to Salmonella infection in vitro and the Salmonella- induced monocytosis and tumor necrosis factor alpha production by myeloid cells was repressed in pigs coinfected with Ascaris . Hence, our data indicate that acute Ascaris infection modulates different immune effector functions with important consequences for the control of tissue-invasive coinfecting pathogens.IMPORTANCEIn experimentally infected pigs, we show that an ongoing infection with the parasitic worm Ascaris suum modulates host immunity, and coinfected pigs have higher Salmonella burdens compared to pigs infected with Salmonella alone. Both infections are widespread in pig production and the prevalence of Salmonella is high in endemic regions of human Ascariasis, indicating that this is a clinically meaningful coinfection. We observed the type 2/regulatory immune response to be induced during an Ascaris infection correlates with increased susceptibility of pigs to the concurrent bacterial infection., Competing Interests: The authors declare no conflict of interest.

Objective: Mutations in presenilin genes are the major cause of Alzheimer's disease. However, little is known about their expression and function in the gut. In this study, we identify the presenilins Psen1 and Psen2 as key molecules that maintain intestinal homoeostasis., Design: Human inflammatory bowel disease (IBD) and control samples were analysed for Psen1 expression. Newly generated intestinal epithelium-specific Psen1-deficient, Psen2-deficient and inducible Psen1/Psen2 double-deficient mice were used to dissect the functional role of presenilins in intestinal homoeostasis., Results: Psen1 expression was regulated in experimental gut inflammation and in patients with IBD. Induced deletion of Psen1 and Psen2 in mice caused rapid weight loss and spontaneous development of intestinal inflammation. Mice exhibited epithelial barrier disruption with bacterial translocation and deregulation of key pathways for nutrient uptake. Wasting disease was independent of gut inflammation and dysbiosis, as depletion of microbiota rescued Psen-deficient animals from spontaneous colitis development but not from weight loss. On a molecular level, intestinal epithelial cells lacking Psen showed impaired Notch signalling and dysregulated epithelial differentiation., Conclusion: Overall, our study provides evidence that Psen1 and Psen2 are important guardians of intestinal homoeostasis and future targets for barrier-promoting therapeutic strategies in IBD., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aims: Fistula formation is a major complication in Crohn's disease [CD] and the role of the immune cell compartment remains to be elucidated. Thus, we compared the immune cell compartment of CD fistula to inflammatory CD colitis using imaging mass cytometry [IMC] and immunofluorescence., Methods: A 36-marker panel including structural, functional, and lineage markers for use in IMC was established. This panel was applied to analyse paraffin-embedded CD fistula tract [n = 11], CD colitis [n = 10], and colon samples from non-inflamed controls [n = 12]. Computational methods for cell segmentation, dimensionality reduction, and cell type clustering were used to define cell populations for cell frequency, marker distribution, and spatial neighbourhood analysis. Multiplex immunofluorescence was used for higher resolution spatial analysis., Results: Analysis of cell frequencies in CD fistulas compared to CD colitis and control colonic samples revealed a significant increase in neutrophils, effector cytotoxic T cells, and inflammatory macrophages in CD fistula samples, whereas regulatory T cells were decreased. Neutrophils in CD fistula expressed significantly more matrix metalloproteinase 9 [MMP9], correlating with extracellular matrix remodelling. Neighbourhood analysis revealed a strong association between MMP9+ neutrophils and effector cytotoxic T cells in both CD fistulas and colitis., Conclusions: This study presents the first highly multiplexed single cell analysis of the immune cell compartment of CD fistulas and their spatial context. It links immune cell dynamics, particularly MMP9+ neutrophils, to extracellular matrix remodelling in CD fistulas, offering insights into the complex network of cellular interactions and potential therapeutic targets for CD complications., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: While standard clinical magnetic resonance (MR) enterography can detect inflammatory bowel disease, it is of limited value in deciding between medical versus surgical treatment. Alternatively, intestinal MR elastography has the potential to contribute additional information to therapeutic decision-making; however, the influence of bowel distension by oral contrast agent on viscoelastic tissue properties remains elusive. Therefore, we aimed to investigate the influence of oral contrast agent-induced bowel distension on the viscoelastic properties of the terminal ileum in healthy volunteers., Methods: In this prospective pilot study, 20 healthy volunteers (33.2±8.2 years; 10 men, 10 women) underwent multifrequency MR elastography using a single-shot spin-echo echo planar imaging sequence at 1.5 Tesla and drive frequencies of 40, 50, 60 and 70 Hz. Maps of shear wave speed ( c in ms -1 ) and loss angle ( φ in rad), representing stiffness and viscous properties, respectively, were generated using tomoelastography data processing. The volunteers were scanned before and after ingestion of 1,000 mL of 2% mannitol solution as oral contrast agent., Results: There was no significant difference in terminal ileum biomechanical properties before vs. after ingestion of an oral contrast agent (mean c : 1.47±0.24 vs. 1.40±0.25 ms -1 with P=0.37; mean φ : 0.70±0.12 rad vs. 0.68±0.12 rad with P=0.61). Moreover, there was no statistically significant correlation between MR elastography parameters before and after the ingestion of oral contrast ( c : r =0.22, P=0.36; φ : r =0.24, P=0.30)., Conclusions: The results of this study suggest that bowel distension for intestinal MR elastography has no systematic effect on the biomechanical tissue properties of the terminal ileum determined by MR elastography. Therefore, future study protocols appear feasible with or without oral contrast agents., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-101/coif). B.S., A.A.K., B.H., J.B., I.S., and R.R. report that this study was funded by the German Research Foundation. B.H. is Grant recipient from Abbott, AbbVie, Ablative Solutions, Accovion, Achogen Inc., Actelion Pharmaceuticals, ADIR, Aesculap, Agios Pharmaceuticals, INC., AGO, Arbeitsgemeinschaft industrieller Forschungsvereinigungen, Arbeitsgemeinschaft internistische Onkologie, Aktionsbündnis Partnersicherheit e.V., Alexion Pharmaceuticals, Amgen, AO Foundation, Aravive, Arena Pharmaceuticals, ARMO Biosciences, Inc., Array Biopharma Inc., Art photonics GmbH Berlin, ASAS, Ascelia Pharma AB, Ascendis, Advanced sleep research, Astrellas, AstraZeneca, August Research OOF, Sofia, BG, BARD, Basiliea, Bayer Healthcare, Bayer Schering Pharma, Bayer Vital, BBraun, BerGenBioASA, Berlin-Brandenburger Centrum für regenerative Therapie, Berliner Krebsgesellschaft, Biontech Mainz, BioNTech SE, Biotronik, Bioven, BMBF, BMS, Boehring Ingelheimer, Boston Biomedical Inc., Boston Scientific Medizintechnik GmbH, BRACCO Group, Brahms GmbH, Brainsgate, Bistol-Myers Squibb, Calithera Biosciences UK, Cantargia AB, Medicon Village, Cascadian Therapeutics, Inc., Celgene, CELLACT Pharma, Celldex Therapeutics, Cellestia Biotech AG CH, CeloNova BioSciences, and Charité research organization GmbH. B.S. has served as consultant for Abbvie, Abivax, BMS, Boehringer, CED Service GmbH, Endpoint Health, Falk, Galapagos, Janssen, Lilly, Pfizer, Takeda, and Predictimmune; he received speaker fees from: AbbVie, BMS, CED Service GmbH, Falk, Ferring, Galapagos, Janssen, Lilly, Materia Prima, Takeda, Pfizer and grant support by Arena/Pfizer (served as representative of the Charité). The other authors have no conflicts of interest to declare., (2024 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Helminth infections lead to an overdispersion of the parasites in humans as well as in animals. We asked whether early immune responses against migrating Ascaris larvae are responsible for the unequal distribution of worms in natural host populations and thus investigated a susceptible versus a resistant mouse strain. In mice, the roundworm larvae develop until the lung stage and thus early anti-Ascaris immune responses against the migrating larvae in the liver and lung can be deciphered. Our data show that susceptible C57BL/6 mice respond to Ascaris larval migration significantly stronger compared to resistant CBA mice and the anti-parasite reactivity is associated with pathology. Increased eosinophil recruitment was detected in the liver and lungs, but also in the spleen and peritoneal cavity of susceptible mice on day 8 post infection compared to resistant mice. In serum, eosinophil peroxidase levels were significantly higher only in the susceptible mice, indicating functional activity of the recruited eosinophils. This effect was associated with an increased IL-5/IL-13 production by innate lymphoid cells and CD4 + T cells and a pronounced type 2 macrophage polarization in the lungs of susceptible mice. Furthermore, a comparison of wildtype BALB/c and eosinophil-deficient dblGATA-1 BALB/c mice showed that eosinophils were not essential for the early control of migrating Ascaris larvae. In conclusion, in primary infection, a strong local and systemic type 2 immune response during hepato-tracheal helminth larval migration is associated with pathology rather than protection., (© 2024. The Author(s).)

The small-molecule inhibitor of ataxia telangiectasia and Rad3-related protein (ATR), elimusertib, is currently being tested clinically in various cancer entities in adults and children. Its preclinical antitumor activity in pediatric malignancies, however, is largely unknown. We here assessed the preclinical activity of elimusertib in 38 cell lines and 32 patient-derived xenograft (PDX) models derived from common pediatric solid tumor entities. Detailed in vitro and in vivo molecular characterization of the treated models enabled the evaluation of response biomarkers. Pronounced objective response rates were observed for elimusertib monotherapy in PDX, when treated with a regimen currently used in clinical trials. Strikingly, elimusertib showed stronger antitumor effects than some standard-of-care chemotherapies, particularly in alveolar rhabdomysarcoma PDX. Thus, elimusertib has strong preclinical antitumor activity in pediatric solid tumor models, which may translate to clinically meaningful responses in patients., (©2023 The Authors; Published by the American Association for Cancer Research.)

Background: Emerging evidence suggests that treatment of NSCLC brain metastases with immune checkpoint inhibitors (ICIs) is associated with response rates similar to those of extracranial disease. Programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) serves as a predictive biomarker for ICI response. However, the predictive value of brain metastasis-specific (intracranial) PD-L1 TPS is not established. We investigated the role of intra- and extracranial PD-L1 TPS in NSCLC patients treated with ICI following brain metastasis resection., Methods: Clinical data from NSCLC patients treated with ICI following brain metastasis resection (n = 64) were analyzed. PD-L1 TPS of brain metastases (n = 64) and available matched extracranial tumor tissue (n = 44) were assessed via immunohistochemistry. Statistical analyses included cut point estimation via maximally selected rank statistics, Kaplan-Meier estimates, and multivariable Cox regression analysis for intracranial progression-free survival (icPFS), extracranial progression-free survival (ecPFS), and overall survival (OS)., Results: PD-L1 expression was found in 54.7% of brain metastases and 68.2% of extracranial tumor tissues, with a median intra- and extracranial PD-L1 TPS of 7.5% (0 - 50%, IQR) and 15.0% (0 - 80%, IQR), respectively. In matched tissue samples, extracranial PD-L1 TPS was significantly higher than intracranial PD-L1 TPS (p = 0.013). Optimal cut points for intracranial and extracranial PD-L1 TPS varied according to outcome parameter assessed. Notably, patients with a high intracranial PD-L1 TPS (> 40%) exhibited significantly longer icPFS as compared to patients with a low intracranial PD-L1 TPS (≤ 40%). The cut point of 40% for intracranial PD-L1 TPS was independently associated with OS, icPFS and ecPFS in multivariable analyses., Conclusion: Our study highlights the potential role of intracranial PD-L1 TPS in NSCLC, which could be used to predict ICI response in cases where extracranial tissue is not available for PD-L1 assessment as well as to specifically predict intracranial response., (© 2024. The Author(s).)

The IL-6-gp130-STAT3 signaling axis is a major regulator of inflammation. Activating mutations in the gene encoding gp130 and germline gain-of-function mutations in STAT3 (STAT3 GOF ) are associated with multi-organ autoimmunity, severe morbidity, and adverse prognosis. To dissect crucial cellular subsets and disease biology involved in activated gp130 signaling, the gp130-JAK-STAT3 axis was constitutively activated using a transgene, L-gp130 , specifically targeted to T cells. Activating gp130 signaling in T cells in vivo resulted in fatal, early onset, multi-organ autoimmunity in mice that resembled human STAT3 GOF disease. Female mice had more rapid disease progression than male mice. On a cellular level, gp130 signaling induced the activation and effector cell differentiation of T cells, promoted the expansion of T helper type 17 (T H 17) cells, and impaired the activity of regulatory T cells. Transcriptomic profiling of CD4 + and CD8 + T cells from these mice revealed commonly dysregulated genes and a gene signature that, when applied to human transcriptomic data, improved the segregation of patients with transcriptionally diverse STAT3 GOF mutations from healthy controls. The findings demonstrate that increased gp130-STAT3 signaling leads to T H 17-driven autoimmunity that phenotypically resembles human STAT3 GOF disease.

Background and Aims: Pain is a cardinal symptom in inflammatory bowel disease [IBD]. An important structure in the transduction of pain signalling is the myenteric plexus [MP]. Nevertheless, IBD-associated infiltration of the MP by immune cells lacks in-depth characterisation. Herein, we decipher intra- and periganglionic immune cell infiltrations in Crohn´s disease [CD] and ulcerative colitis [UC] and provide a comparison with murine models of colitis., Methods: Full wall specimens of surgical colon resections served to examine immune cell populations by either conventional immuno-histochemistry or immunofluorescence followed by either bright field or confocal microscopy. Results were compared with equivalent examinations in various murine models of intestinal inflammation., Results: Whereas the MP morphology was not significantly altered in IBD, we identified intraganglionic IBD-specific B cell- and monocyte-dominant cell infiltrations in CD. In contrast, UC-MPs were infiltrated by CD8+ T cells and revealed a higher extent of ganglionic cell apoptosis. With regard to the murine models of intestinal inflammation, the chronic dextran sulphate sodium [DSS]-induced colitis model reflected CD [and to a lesser extent UC] best, as it also showed increased monocytic infiltration as well as a modest B cell and CD8+ T cell infiltration., Conclusions: In CD, MPs were infiltrated by B cells and monocytes. In UC, mostly CD8+ cytotoxic T cells were found. The chronic DSS-induced colitis in the mouse model reflected best the MP-immune cell infiltrations representative for IBD., (© The Author(s) 2023. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation.)

Objective: We sought to investigate the role of interleukin (IL)-20 in IBD and experimental colitis., Design: Experimental colitis was induced in mice deficient in components of the IL-20 and signal transducer and activator of transcription (STAT)2 signalling pathways. In vivo imaging, high-resolution mini-endoscopy and histology were used to assess intestinal inflammation. We further used RNA-sequencing (RNA-Seq), RNAScope and Gene Ontology analysis, western blot analysis and co-immunoprecipitation, confocal microscopy and intestinal epithelial cell (IEC)-derived three-dimensional organoids to investigate the underlying molecular mechanisms. Results were validated using samples from patients with IBD and non-IBD control subjects by a combination of RNA-Seq, organoids and immunostainings., Results: In IBD, IL20 levels were induced during remission and were significantly higher in antitumour necrosis factor responders versus non-responders. IL-20RA and IL-20RB were present on IECs from patients with IBD and IL-20-induced STAT3 and suppressed interferon (IFN)-STAT2 signalling in these cells. In IBD, experimental dextran sulfate sodium (DSS)-induced colitis and mucosal healing, IECs were the main producers of IL-20. Compared with wildtype controls, Il20 -/- , Il20ra -/- and Il20rb -/- mice were more susceptible to experimental DSS-induced colitis. IL-20 deficiency was associated with increased IFN/STAT2 activity in mice and IFN/STAT2-induced necroptotic cell death in IEC-derived organoids could be markedly blocked by IL-20. Moreover, newly generated Stat2 ΔIEC mice, lacking STAT2 in IECs, were less susceptible to experimental colitis compared with wildtype controls and the administration of IL-20 suppressed colitis activity in wildtype animals., Conclusion: IL-20 controls colitis and mucosal healing by interfering with the IFN/STAT2 death signalling pathway in IECs. These results indicate new directions for suppressing gut inflammation by modulating IL-20-controlled STAT2 signals., Competing Interests: Competing interests: MFN has served as an advisor for Pentax, Giuliani, PPM, BMS, Janssen, MSD, Takeda and Boehringer. MFN has served as an Associate Editor of the journal/Editorial Board Member. BS has served as consultant for AbbVie, Arena, BMS, Boehringer, Celgene, Falk, Galapagos, Janssen, Lilly, Pfizer, Prometheus and Takeda and received speaker’s fees from AbbVie, CED Service, Falk, Ferring, Janssen, Novartis, Pfizer, Takeda (served as representative of the Charité). All other authors have nothing to disclose., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Multiple sclerosis (MS) is a chronic neuroinflammatory disease that involves both white and gray matter. Although gray matter damage is a major contributor to disability in MS patients, conventional clinical magnetic resonance imaging (MRI) fails to accurately detect gray matter pathology and establish a clear correlation with clinical symptoms. Using magnetic resonance elastography (MRE), we previously reported global brain softening in MS and experimental autoimmune encephalomyelitis (EAE). However, it needs to be established if changes of the spatiotemporal patterns of brain tissue mechanics constitute a marker of neuroinflammation. Here, we use advanced multifrequency MRE with tomoelastography postprocessing to investigate longitudinal and regional inflammation-induced tissue changes in EAE and in a small group of MS patients. Surprisingly, we found reversible softening in synchrony with the EAE disease course predominantly in the cortex of the mouse brain. This cortical softening was associated neither with a shift of tissue water compartments as quantified by T2-mapping and diffusion-weighted MRI, nor with leukocyte infiltration as seen by histopathology. Instead, cortical softening correlated with transient structural remodeling of perineuronal nets (PNNs), which involved abnormal chondroitin sulfate expression and microgliosis. These mechanisms also appear to be critical in humans with MS, where tomoelastography for the first time demonstrated marked cortical softening. Taken together, our study shows that neuroinflammation (i) critically affects the integrity of PNNs in cortical brain tissue, in a reversible process that correlates with disease disability in EAE, (ii) reduces the mechanical integrity of brain tissue rather than leading to water accumulation, and (iii) shows similar spatial patterns in humans and mice. These results raise the prospect of leveraging MRE and quantitative MRI for MS staging and monitoring treatment in affected patients., (© 2024. The Author(s).)

Gut microbiota-derived metabolites play a pivotal role in the maintenance of intestinal immune homeostasis. Here, we demonstrate that the human commensal Clostridium sporogenes possesses a specific metabolic fingerprint, consisting predominantly of the tryptophan catabolite indole-3-propionic acid (IPA), the branched-chain acids (BCFAs) isobutyrate and isovalerate and the short-chain fatty acids (SCFAs) acetate and propionate. Mono-colonization of germ-free mice with C. sporogenes (CS mice) affected colonic mucosal immune cell phenotypes, including up-regulation of Il22 gene expression, and increased abundance of transcriptionally active colonic tuft cells and Foxp3 + regulatory T cells (Tregs). In DSS-induced colitis, conventional mice suffered severe inflammation accompanied by loss of colonic crypts. These symptoms were absent in CS mice. In conventional, but not CS mice, bulk RNAseq analysis of the colon revealed an increase in inflammatory and Th17-related gene signatures. C. sporogenes -derived IPA reduced IL-17A protein expression by suppressing mTOR activity and by altering ribosome-related pathways in Th17 cells. Additionally, BCFAs and SCFAs generated by C. sporogenes enhanced the activity of Tregs and increased the production of IL-22, which led to protection from colitis. Collectively, we identified C. sporogenes as a therapeutically relevant probiotic bacterium that might be employed in patients with inflammatory bowel disease (IBD).

Introduction: The human intestinal tract reacts to extensive resection with spontaneous intestinal adaptation. We analyzed whether gene expression analyses or intestinal permeability (IP) testing could provide biomarkers to describe regulation mechanisms in the intestinal barrier in short bowel syndrome (SBS) patients during adaptive response or treatment with the glucagon-like peptide-2 analog teduglutide., Methods: Relevant regions of the GLP-2 receptor gene were sequenced. Gene expression analyses and immunohistochemistry were performed from mucosal biopsies. IP was assessed using a carbohydrate oral ingestion test., Results: The study includes 59 SBS patients and 19 controls. Increases in gene expression with teduglutide were received for sucrase-isomaltase, sodium/glucose cotransporter 1, and calcium/calmodulin serine protein kinase. Mannitol recovery was decreased in SBS but elevated with teduglutide (Δ 40%), showed a positive correlation with remnant small bowel and an inverse correlation with parenteral support., Conclusions: Biomarkers predicting clinical and functional features in human SBS are very limited. Altered specific gene expression was shown for genes involved in nutrient transport but not for genes controlling tight junctions. However, mannitol recovery proved useful in describing the absorptive capacity of the gut during adaptation and treatment with teduglutide.

Background: Although there is growing evidence that functional involvement and structural changes of mesenteric adipose tissue (MAT) influence the course of Crohn's disease (CD), its viscoelastic properties remain elusive. Therefore, we aimed to investigate the viscoelastic properties of MAT in CD using magnetic resonance elastography (MRE), providing reference values for CD diagnosis., Methods: In this prospective proof-of-concept study, 31 subjects (CD: n=11; healthy controls: n=20) were consecutively enrolled in a specialized care center for inflammatory bowel diseases (tertiary/quaternary care). Inclusion criteria for the CD patients were a clinically and endoscopically established diagnosis of CD based on the clinical record, absence of other concurrent bowel diseases, scheduled surgery for the following day, and age of at least 18 years. Diagnoses were confirmed by histological analysis of the resected bowel the day after MRE. Subjects were investigated using MRE at 1.5-T with frequencies of 40-70 Hz. To retrieve shear wave speed (SWS), volumes of interest (VOIs) in MAT were drawn adjacent to CD lesions (MAT CD ) and on the opposite side without adjacent bowel lesions in patients (MAT CD_Opp ) and controls (MAT CTRL ). The presented study is not registered in the clinical trial platform., Results: A statistically significant decrease in mean SWS of 7% was found for MAT CD_Opp vs. MAT CTRL (0.76±0.05 vs. 0.82±0.04 m/s, P=0.012), whereas there was a nonsignificant trend with an 8% increase for MAT CD vs. MAT CD_Opp (0.82±0.07 vs. 0.76±0.05 m/s, P=0.098) and no difference for MAT CD vs. MAT CTRL . Preliminary area under the receiver operating characteristic curve (AUC) analysis showed diagnostic accuracy in detecting CD to be excellent for SWS of MAT CD_Opp [AUC =0.82; 95% confidence interval (CI): 0.64-0.96] but poor for SWS of MAT CD (AUC =0.52; 95% CI: 0.34-0.73)., Conclusions: This study demonstrates the feasibility of MRE of MAT and presents preliminary reference values for CD patients and healthy controls. Our results motivate further studies for the biophysical characterization of MAT in inflammatory bowel disease., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-41/coif). BH, IS, PA, AAK, and BS report that this study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation): SFB 1340/1 “Matrix in Vision” project number 372486779; IS reports that this study was funded by GRK 2260 BIOQIC; RR reports that this study was funded by RE 4161/2-1; AAK, CW, and BS report that this study was funded by SFB-TR 241 “IEC in IBD”. RR is a participant of the BIH-Charité Digital Clinician Scientist Program funded by Charité – Universitätsmedizin Berlin, Berlin Institute of Health and the DFG. BS has received grant money from Pfizer, consultancy fees from Abbvie, Arena Pharma, Boehringer, BMS, Celgene, CT-Scout, Galapagos, Gilead, Janssen, Lilly, Pfizer, PredictImmune, PsiCro, and honoraria for lectures, presentations from Abbvie, CED Service GmbH, CHiesi, Galapagos, Falk Foundation, Forga Software, IBD passport, Janssen, Materia Prima, Pfizer, Lilly (all payments were made to Charité). BH is a grant recipient for the Department of Radiology from Abbott, AbbVie, Ablative Solutions, Accovion, Achogen Inc., Actelion Pharmaceuticals, ADIR, Aesculap, Agios Pharmaceuticals, Inc., AGO, Arbeitsgemeinschaft Industrieller Forschungsvereinigungen (AIF), Arbeitsgemeinschaft Internistische Onkologie (AIO), Aktionsbündnis Partnersicherheit e.V., Alexion Pharmaceuticals, Amgen, AO Foundation, Aravive, Arena Pharmaceuticals, ARMO Biosciences, Inc., Array Biopharma Inc., Art Photonics GmbH Berlin, ASAS, Ascelia Pharma AB, Ascendis, ASR Advanced Sleep Research, Astrellas, AstraZeneca, August Research OOF, Sofia, BG, BARD, Basiliea, Bayer Healthcare, Bayer Schering Pharma, Bayer Vital, BBraun, BerGenBioASA, Berlin-Brandenburger Centrum für Regenerative Therapie (BCRT), Berliner Krebsgesellschaft, Biontech Mainz, BioNTech SE, Biotronik, Bioven, BMBF, BMS, Boehring Ingelheimer, Boston Biomedical Inc., Boston Scientific Medizintechnik GmbH, BRACCO Group, Brahms GmbH, Brainsgate, Bistol-Myers Squibb, Calithera Biosciences UK, Cantargia AB, Medicon Village, Cascadian Therapeutics, Inc., Celgene, CELLACT Pharma, Celldex Therapeutics, Cellestia Biotech AG CH, CeloNova BioSciences, Charité Research Organization GmbH, Chiltern, Clovis Oncology, Inc., Covance, CRO Charité, CTI Ulm, CUBIST, CureVac AG, Tübingen, Curis, Daiichi Sankyo, Dartmouth College, Hanover, NH, USA, DC Devices, Inc. USA, Delcath Systems, Dermira Inc., Deutsche Krebshilfe, Deutsche Rheuma Liga, DZ-Deutsche Diabetes Forschungsgesellschaft e.V., Deutsches Zentrum für Luft- und Raumfahrt e.V., DFG, Dr. Falk Pharma GmbH, DSM Nutritional Products AG, Dt. Gesellschaft für Muskuloskelettale Radiologie, Dt. Stiftung für Herzforschung, Dynavax, Aisai Ltd., European Knowledge Centre, Mosquito Way, Hatfield, Eli Lilly and Company Ltd., EORTC, Episurf Medical, Epizyme, Inc., Essex Pharma, EU Programmes, European Society of Gastrointestinal and Abdominal Radiology, Euroscreen S.A., F20 Biotech GmbH, Ferring Pharmaceuticals A/S, Fibrex Medical Inc., Focused Ultrasound Surgery Foundation, Fraunhofer Gesellschaft, GALA Therapeutics, US, Galena Biopharma, Galmed Research and Development Ltd., Ganymed, GBG Forschungs GmbH, GE, Gentech. Inc., Genmab A/S, Genzyme Europe B.V., GETNE (Grupo Espanol de Tumores Neuroendocrinos), Gilead Sciences, Inc., Glaxo Smith Kline, Glycotype GmbH Berlin, Goethe Uni Frankfurt, Guerbet, Guidant Europe NV, Halozyme, Hans-Böckler-Stiftung, Hewlett Packard GmbH, Holaira Inc., Horizon Therapeutics Ireland, ICON (CRO), Idera Pharmaceuticals, Inc., Ignyta, Inc., Immunomedics Inc., Immunocore, Inari Medical Europe GmbH Basel, Incyte, INC Research, Innate Pharma, InSightec Ltd., Inspiremd, InVentiv Health Clinical UK Ltd., Inventivhealth, IO Biotech ApS Copenhagen, IOMEDICO, IONIS, IPSEN Pharma, IQVIA ISA Therapeutics, Isis Pharmaceuticals Inc., ITM Solucin GmbH, Jansen-Cilag GmbH, Kantar Health GmbH (CRO), Kartos Therapeutics, Inc., Karyopharm Therapeutics, Inc., Kendle/MorphoSys AG, Kite Pharma, Kli Fo Berlin Mitte, Kura Oncology, Labcorb, La Roche, Land Berlin, Lilly GmbH, Lion Biotechnology, Lombard Medical, Loxo Oncology, Inc., LSK BioPartners, USA, Lundbeck GmbH, LUX Biosciences, LYSARC, MacroGenics, MagForce, MedImmune Inc., MedImmune Limited, Medpace, Medpace Germany GmbH (CRO), MedPass (CRO), Medtronic, Medtraveo GmbH, Merck, Merrimack Pharmaceuticals Inc., MeVis Medical Solutions AG, Millenium Pharmaceuticals Inc., Miltenyi Biomedicine GmbH, Bergisch Gladbach, miRagen Boukider, Mologen, Monika Kutzner Stiftung, MophoSys AG, MSD Sharp, Nektar Therapeutics, NeoVacs SA, Netzwerkverbund Radiologie, Neurocrine Biosciences Inc., US, Newlink Genetics Corporation, Nexus Oncology, NIH, NOGGO Berlin, Nord-Ostddeutsche Gesellschaft e.V., Novartis, Novocure, Nuvisan, Ockham oncology, Odonate Therapeutics San Diego, OHIRC Kanada, Oppilan Pharma Ltd., London, Orion Corporation Orion Pharma, OSE Immunotherapeutics, Parexel CRO Service, Pentixal Pharma GmbH Perceptive, Pfizer GmbH, PharmaCept GmbH, Pharma Mar, Pharmaceutical Reseach Associates GmbH (PRA), Pharmacyclics Inc., Philipps, Philogen s.p.a. Siena, Pliant Therapeutics San Francisco, PIQUR Therapeutics Ltd., Pluristem, PneuRX.Inc., Portola Pharmaceuticals, PPD (CRO), PRaint, Precision GmbH, Premier-Research, Priovant Therapeutics USA, Provectus Biopharmaceuticals, Inc., Psi-Cro, Pulmonx International Sarl, Quintiles GmbH, Radiobotics ApS, Regeneraon Pharmaceuticals Inc., Replimune, Respicardia, Rhythm Pharmaceuticals, Inc. Boston USA, Roche, Salix Pharmaceuticals Inc., Samsung, Sanofi, Sanofis-Aventis S.A., Sarepta Therapeutics, Cambridge, US, Saving Patient’s Lives Medical B.V., Schumacher GmbH, Seagen, Seattle Genetics, Servier (CRO), SGS Life Science Sercives (CRO), Shape Memorial Midical Inc., USA, Shire Human Genetic Therapies, Siemens, Silena Therapeutics, SIRTEX Medical Europe GmbH, SOTIO Biotech, Boston, Spectranetics GmbH, Spectrum Pharmaceuticals, Stiftung Charite/BIH, St. Jude Medical, Stiftung Wolfgang Schulze, Syneos Health UK, Ltd., Symphogen, Taiho Oncology, Inc., Taiho Pharmaceutical Co., Target Pharma Solutions Inc., TauRx Therapeutics Ltd., Terumo Medical Corporation, Tesaro, Tetec-Ag, TEVA, Theorem, Theradex, Theravance, Threshold Pharmaceuticals Inc., TNS Healthcare GmbH, Toshiba, UCB Pharma, Ulrich GmbH Ulm, Uni Jena, Uni München, Uni Tübingen, Vaccibody A.S., VDI/VDE, Vertex Pharmaceuticals Incorporated, Viridian Therapeutics, US, Virtualscopis LLC, Winicker-Norimed, Wyeth Pharma, Xcovery Holding Company, and Zukunftsfond Berlin (TSB) outside the presented study. The other authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Inflammatory bowel disease (IBD) is an immune-mediated gut dysfunction, which might also be associated with an inflammatory phenotype in the liver. It is known that the nutritional intake of omega-3 polyunsaturated fatty acids (n-3 PUFA) is inversely correlated to the severity and occurrence of IBD. In order to investigate whether n-3 PUFA can also reduce liver inflammation and oxidative liver damage due to colon inflammation, we explored the dextran sulfate sodium (DSS)-induced colitis model in wild-type and fat-1 mice with endogenously increased n-3 PUFA tissue content. Besides confirming previous data of alleviated DSS-induced colitis in the fat-1 mouse model, the increase of n-3 PUFA also resulted in a significant reduction of liver inflammation and oxidative damage in colitis-affected fat-1 mice as compared to wild-type littermates. This was accompanied by a remarkable increase of established inflammation-dampening n-3 PUFA oxylipins, namely docosahexaenoic acid-derived 19,20-epoxydocosapentaenoic acid and eicosapentaenoic acid-derived 15-hydroxyeicosapentaenoic acid and 17,18-epoxyeicosatetraenoic acid. Taken together, these observations demonstrate a strong inverse correlation between the anti-inflammatory lipidome derived from n-3 PUFA and the colitis-triggered inflammatory changes in the liver by reducing oxidative liver stress., Competing Interests: Declaration of competing interest All authors declare that there are no conflicts of interest to be disclosed., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Fibrostenotic disease is a common complication in Crohn's disease (CD) patients hallmarked by transmural extracellular matrix (ECM) accumulation in the intestinal wall. The prevention and medical therapy of fibrostenotic CD is an unmet high clinical need. Although targeting IL36R signaling is a promising therapy option, downstream mediators of IL36 during inflammation and fibrosis have been incompletely understood. Candidate molecules include matrix metalloproteinases which mediate ECM turnover and are thereby potential targets for anti-fibrotic treatment. Here, we have focused on understanding the role of MMP13 during intestinal fibrosis., Methods: We performed bulk RNA sequencing of paired colon biopsies taken from non-stenotic and stenotic areas of patients with CD. Corresponding tissue samples from healthy controls and CD patients with stenosis were used for immunofluorescent (IF) staining. MMP13 gene expression was analyzed in cDNA of intestinal biopsies from healthy controls and in subpopulations of patients with CD in the IBDome cohort. In addition, gene regulation on RNA and protein level was studied in colon tissue and primary intestinal fibroblasts from mice upon IL36R activation or blockade. Finally, in vivo studies were performed with MMP13 deficient mice and littermate controls in an experimental model of intestinal fibrosis. Ex vivo tissue analysis included Masson's Trichrome and Sirius Red staining as well as evaluation of immune cells, fibroblasts and collagen VI by IF analysis., Results: Bulk RNA sequencing revealed high upregulation of MMP13 in colon biopsies from stenotic areas, as compared to non-stenotic regions of patients with CD. IF analysis confirmed higher levels of MMP13 in stenotic tissue sections of CD patients and demonstrated αSMA+ and Pdpn+ fibroblasts as a major source. Mechanistic experiments demonstrated that MMP13 expression was regulated by IL36R signaling. Finally, MMP13 deficient mice, as compared to littermate controls, developed less fibrosis in the chronic DSS model and showed reduced numbers of αSMA+ fibroblasts. These findings are consistent with a model suggesting a molecular axis involving IL36R activation in gut resident fibroblasts and MMP13 expression during the pathogenesis of intestinal fibrosis., Conclusion: Targeting IL36R-inducible MMP13 could evolve as a promising approach to interfere with the development and progression of intestinal fibrosis., Competing Interests: Author PB was employed by Boehringer Ingelheim Pharma GmbH & Co KG. Author JR was employed by Staburo GmbH. Author AM was employed by Boehringer Ingelheim Pharmaceuticals Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Koop, Enderle, Hillmann, Ruspeckhofer, Vieth, Sturm, Trajanoski, Kühl, Atreya, Leppkes, Baum, Roy, Martin, Neurath and Neufert.)

The paracaspase MALT1 is a crucial regulator of immune responses in various cellular contexts. Recently, there is increasing evidence suggesting that MALT1 might represent a novel key player in mucosal inflammation. However, the molecular mechanisms underlying this process and the targeted cell population remain unclear. In this study, we investigate the role of MALT1 proteolytic activity in the context of mucosal inflammation. We demonstrate a significant enrichment of MALT1 gene and protein expression in colonic epithelial cells of UC patients, as well as in the context of experimental colitis. Mechanistically we demonstrate that MALT1 protease function inhibits ferroptosis, a form of iron-dependent cell death, upstream of NF-κB signaling, which can promote inflammation and tissue damage in IBD. We further show that MALT1 activity contributes to STAT3 signaling, which is essential for the regeneration of the intestinal epithelium after injury. In summary, our data strongly suggests that the protease function of MALT1 plays a critical role in the regulation of immune and inflammatory responses, as well as mucosal healing. Understanding the mechanisms by which MALT1 protease function regulates these processes may offer novel therapeutic targets for the treatment of IBD and other inflammatory diseases., Competing Interests: Authors declare no conflict of interest.

Toll-like receptors (TLR) control the activation of dendritic cells that prime CD4 + T cells in draining lymph nodes, where these T cells then undergo massive clonal expansion. The mechanisms controlling this clonal T cell expansion are poorly defined. Using the CD4 + T cell-mediated disease experimental autoimmune encephalomyelitis (EAE), we show here that this process is markedly suppressed when TLR9 signaling is increased, without noticeably affecting the transcriptome of primed T cells, indicating a purely quantitative effect on CD4 + T cell expansion. Addressing the underpinning mechanisms revealed that CD4 + T cell expansion was preceded and depended on the accumulation of neutrophils in lymph nodes a few days after immunization. Underlying the importance of this immune regulation pathway, blocking neutrophil accumulation in lymph nodes by treating mice with a TLR9 agonist inhibited EAE progression in mice with defects in regulatory T cells or regulatory B cells, which otherwise developed a severe chronic disease. Collectively, this study demonstrates the key role of neutrophils in the quantitative regulation of antigen-specific CD4 + T cell expansion in lymph nodes, and the counter-regulatory role of TLR signaling in this process., (© 2022 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

Background: Though evidence on the detrimental impact of the COVID-19 pandemic in nursing homes is vast, research focusing on general practitioners' (GP) care during the pandemic in nursing homes is still scarce., Methods: A retrospective online survey among 1,010 nursing home managers in Germany was conducted during the first wave of the COVID-19 pandemic between November 2020 and February 2021. Associations between perceived deficits in GP care (routine and acute visits) and both general and COVID-19-related characteristics of nursing homes were analysed using multiple logistic regression analyses., Results: The majority of nursing home managers reported no deficits in GP care (routine visits, 84.3%; acute visits, 92.9%). Logistic regression analyses revealed that deficits in GP care (routine visits) were significantly associated with visiting restrictions for GPs and nursing home size. Small nursing homes (1-50 residents) were significantly more likely to report deficits in GP care (routine visits) compared to medium (51-100 residents) and large nursing homes (> 100 residents). Further, deficits in GP care (acute visits) were significantly associated with dementia as a focus of care and the burden of insufficient testing for SARS-CoV-2 among residents. Moreover, visiting restrictions for GPs were significantly associated with dementia as the focus of care and the COVID-19 incidence at the federal state level. Finally, COVID-19 cases in nursing homes were significantly associated with size of nursing homes, COVID-19-incidence on the federal state level and the burden of insufficient testing capacities for SARS-CoV-2 among residents., Conclusion: We found structural factors associated with GP care deficits during the pandemic. New concepts for GP care should be implemented in pandemic preparedness plans to ensure high quality, consistent, and reliable GP care as well as effective infection prevention measures in nursing homes., (© 2022. The Author(s).)

Background: Tissue defects in the annulus fibrosus (AF) due to intervertebral disc (IVD) degeneration or after nucleodiscectomy have little self-healing capacity. To prevent progressive degeneration of the IVD, the AF must be repaired. Biological closure has not yet been achieved and is a challenge for the research community. In this study, a scaffold made of absorbable poly (glycolic acid) (PGA) and hyaluronan (HA) that exhibit excellent biocompatibility and cell colonization properties was used to repair AF defects in an ovine model., Methods: A partial resection was performed in AF in L3/4 or L4/5 of 10 sheep and PGA-HA scaffolds were implanted on the defects (n = 5), while defects in the control group were left untreated (n = 5). Three months post-operation, the lumbar discs were sectioned and stained with hematoxylin and eosin and safranin-O/fast-green. Histological features including proteoglycan content, annular structure, cellular morphology, blood vessel ingrowth and tear/cleft formation were scored using a modified scoring scheme by 3 investigators and evaluated by a pathologist independently., Results: The treated AF exhibited significantly enhanced repair tissue structure with signs of proteoglycan formation compared to the untreated group. The median scores were 4.3 for the treated and 9.8 for the untreated group. Cystic degeneration, perivascular infiltration, inflammation and necrosis were only present in the untreated group. Blood vessel ingrowth and tear/cleft formation were increased, though not significant, in the untreated group while cell morphology was comparable in both groups., Conclusion: PGA-HA scaffolds used for AF closure support repair tissue formation in an ovine lumbar disc defect model., (© 2022. Korean Tissue Engineering and Regenerative Medicine Society.)

Objective: Bleeding ulcers and erosions are hallmarks of active ulcerative colitis (UC). However, the mechanisms controlling bleeding and mucosal haemostasis remain elusive., Design: We used high-resolution endoscopy and colon tissue samples of active UC (n = 36) as well as experimental models of physical and chemical mucosal damage in mice deficient for peptidyl-arginine deiminase-4 (PAD4), gnotobiotic mice and controls. We employed endoscopy, histochemistry, live-cell microscopy and flow cytometry to study eroded mucosal surfaces during mucosal haemostasis., Results: Erosions and ulcerations in UC were covered by fresh blood, haematin or fibrin visible by endoscopy. Fibrin layers rather than fresh blood or haematin on erosions were inversely correlated with rectal bleeding in UC. Fibrin layers contained ample amounts of neutrophils coaggregated with neutrophil extracellular traps (NETs) with detectable activity of PAD. Transcriptome analyses showed significantly elevated PAD4 expression in active UC. In experimentally inflicted wounds, we found that neutrophils underwent NET formation in a PAD4-dependent manner hours after formation of primary blood clots, and remodelled clots to immunothrombi containing citrullinated histones, even in the absence of microbiota. PAD4-deficient mice experienced an exacerbated course of dextrane sodium sulfate-induced colitis with markedly increased rectal bleeding (96 % vs 10 %) as compared with controls. PAD4-deficient mice failed to remodel blood clots on mucosal wounds eliciting impaired healing. Thus, NET-associated immunothrombi are protective in acute colitis, while insufficient immunothrombosis is associated with rectal bleeding., Conclusion: Our findings uncover that neutrophils induce secondary immunothrombosis by PAD4-dependent mechanisms. Insufficient immunothrombosis may favour rectal bleeding in UC., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Protective immunity relies on the interplay of innate and adaptive immune cells with complementary and redundant functions. Innate lymphoid cells (ILCs) have recently emerged as tissue-resident, innate mirror images of the T cell system, with which they share lineage-specifying transcription factors and effector machinery 1 . Located at barrier surfaces, ILCs are among the first responders against invading pathogens and thus could potentially determine the outcome of the immune response 2 . However, so far it has not been possible to dissect the unique contributions of ILCs to protective immunity owing to limitations in specific targeting of ILC subsets. Thus, all of the available data have been generated either in mice lacking the adaptive immune system or with tools that also affect other immune cell subsets. In addition, it has been proposed that ILCs might be dispensable for a proper immune response because other immune cells could compensate for their absence 3-7 . Here we report the generation of a mouse model based on the neuromedin U receptor 1 (Nmur1) promoter as a driver for simultaneous expression of Cre recombinase and green fluorescent protein, which enables gene targeting in group 2 ILCs (ILC2s) without affecting other innate and adaptive immune cells. Using Cre-mediated gene deletion of Id2 and Gata3 in Nmur1-expressing cells, we generated mice with a selective and specific deficiency in ILC2s. ILC2-deficient mice have decreased eosinophil counts at steady state and are unable to recruit eosinophils to the airways in models of allergic asthma. Further, ILC2-deficient mice do not mount an appropriate immune and epithelial type 2 response, resulting in a profound defect in worm expulsion and a non-protective type 3 immune response. In total, our data establish non-redundant functions for ILC2s in the presence of adaptive immune cells at steady state and during disease and argue for a multilayered organization of the immune system on the basis of a spatiotemporal division of labour., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Inflammatory bowel diseases (IBD) comprise mainly ulcerative colitis (UC) and Crohn´s disease (CD). Both forms present with a chronic inflammation of the (gastro) intestinal tract, which induces excessive changes in the composition of the associated extracellular matrix (ECM). In UC, the inflammation is limited to the colon, whereas it can occur throughout the entire gastrointestinal tract in CD. Tools for early diagnosis of IBD are still very limited and highly invasive and measures for standardized evaluation of structural changes are scarce. To investigate an efficient non-invasive way of diagnosing intestinal inflammation and early changes of the ECM, very small superparamagnetic iron oxide nanoparticles (VSOPs) in magnetic resonance imaging (MRI) were applied in two mouse models of experimental colitis: the dextran sulfate sodium (DSS)-induced colitis and the transfer model of colitis. For further validation of ECM changes and inflammation, tissue sections were analyzed by immunohistochemistry. For in depth ex-vivo investigation of VSOPs localization within the tissue, Europium-doped VSOPs served to visualize the contrast agent by imaging mass cytometry (IMC). VSOPs accumulation in the inflamed colon wall of DSS-induced colitis mice was visualized in T 2 * weighted MRI scans. Components of the ECM, especially the hyaluronic acid content, were found to influence VSOPs binding. Using IMC, co-localization of VSOPs with macrophages and endothelial cells in colon tissue was shown. In contrast to the DSS model, colonic inflammation could not be visualized with VSOP-enhanced MRI in transfer colitis. VSOPs present a potential contrast agent for contrast-enhanced MRI to detect intestinal inflammation in mice at an early stage and in a less invasive manner depending on hyaluronic acid content., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Golusda, Kühl, Lehmann, Dahlke, Mueller, Boehm-Sturm, Saatz, Traub, Schnorr, Freise, Taupitz, Biskup, Blanchard, Klein, Sack, Siegmund and Paclik.)

The incidence of inflammatory bowel disease with its two main manifestations, colitis ulcerosa and Crohn's disease, is rising globally year after year. There is still a tremendous need to study the underlying pathomechanisms and a well-established tool in order to better understand the disease are colitis models in rodents. Since the concept of the 3Rs was proposed by Russell and Burch, this would include pain medication in animal models of intestinal inflammation as a reduction of suffering. This review argues against pain medication because the administration of pain medication in its current form has an impact on the inflammatory process and the immune response, thus falsifying the results and the reproducibility and therefore leading to misconceptions., (© 2021 Crohn’s & Colitis Foundation. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation.)

Successful treatment of chronic inflammatory diseases integrates both the cessation of inflammation and the induction of adequate tissue repair processes. Strikingly, targeting a single proinflammatory cytokine, tumor necrosis factor (TNF), induces both processes in a relevant cohort of inflammatory bowel disease (IBD) patients. However, the molecular mechanisms underlying intestinal repair following TNF blockade during IBD remain elusive. Using a novel humanized model of experimental colitis, we demonstrate that TNF interfered with the tissue repair program via induction of a soluble natural antagonist of IL-22 (IL-22Ra2; IL-22BP) in the colon and abrogated IL-22/STAT3-mediated mucosal repair during colitis. Furthermore, membrane-bound TNF expressed by T cells perpetuated colonic inflammation, while soluble TNF produced by epithelial cells (IECs) induced IL-22BP expression in colonic dendritic cells (DCs) and dampened IL-22-driven restitution of colonic epithelial functions. Finally, TNF induced IL-22BP expression in human monocyte-derived DCs and levels of IL22-BP correlated with TNF in sera of IBD patients. Thus, our data can explain how anti-TNF therapy induces mucosal healing by increasing IL-22 availability and implicates new therapeutic opportunities for IBD., (© 2022. The Author(s).)

Intestinal parasitic nematodes affect a quarter of the world's population, typically eliciting prominent effector Th2-driven host immune responses. As not all infected hosts develop protection against reinfection, our current understanding of nematode-induced memory Th2 responses remains limited. Here, we investigated the activation of memory Th2 cells and the mechanisms driving early recall responses to the enteric nematode Heligmosomoides polygyrus in mice. We show that nematode-cured mice harbor memory Th2 cells in lymphoid and non-lymphoid organs with distinct transcriptional profiles, expressing recirculation markers like CCR7 and CD62-L in the mesenteric lymph nodes (mLN), and costimulatory markers like Ox40, as well as tissue homing and activation markers like CCR2, CD69 and CD40L in the gut and peritoneal cavity (PEC). While memory Th2 cells persist systemically in both lymphoid and non-lymphoid tissues following cure of infection, peritoneal memory Th2 cells in particular displayed an initial prominent expansion and strong parasite-specific Th2 responses during early recall responses to a challenge nematode infection. This effect was paralleled by a significant influx of dendritic cells (DC) and eosinophils, both also appearing exclusively in the peritoneal cavity of reinfected mice. In addition, we show that within the peritoneal membrane lined by peritoneal mesothelial cells (PeM), the gene expression levels of cell adhesion markers VCAM-1 and ICAM-1 decrease significantly in response to a secondary infection. Overall, our findings indicate that the host peritoneal cavity in particular harbors prominent memory Th2 cells and appears to respond directly to H. polygyrus by an early recall response via differential regulation of cell adhesion markers, marking the peritoneal cavity an important site for host immune responses to an enteric pathogen., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yordanova, Jürchott, Steinfelder, Vogt, Krüger, Kühl, Sawitzki and Hartmann.)

Within the IBD entity of Crohn's disease, there is currently no differentiation between ileal and colonic manifestation for recruitment of patients in clinical trials, well-powered analysis of study results or therapeutic decisions in daily clinical practice. However, there is accumulating evidence from epidemiological, genetic, microbial, immunological, and clinical characteristics that clearly indicate that ileal Crohn's disease represents a distinct disease entity, which differentiates itself from colonic Crohn's disease. This is also reflected by lower efficacy of targeted therapies in isolated ileal compared to colonic Crohn's disease. The distinct site-specific mechanisms that drive heightened non-response in ileal disease need to be analysed in-depth in the future, to enable optimized therapy in the individual Crohn's disease patient., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: RA has served as a speaker, or consultant, or received research grants from AbbVie, Amgen, Arena Pharmaceuticals, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Cellgene, Celltrion Healthcare, DrFalk Pharma, Ferring, Fresenius Kabi, Galapagos, Gilead, InDex Pharmaceuticals, Janssen-Cilag, Kliniksa Pharmaceuticals, Lilly, MSD Sharp & Dohme, Novartis, Pandion Therapeutics, Pfizer, Roche Pharma, Samsung Bioepsis, Takeda Pharma, Tillotts Pharma AG, Viatris. Research work of RA is funded by the DFG-SFB1181 (Project No. C02) and DFG-SFB/TRR241 (Project No. C02, C03, IBDome). Research work of CB is funded by DFG-SFB/TRR241 (Project No. C02). Research work of AAK, ZT is funded by the DFG-SFB/TRR241 (IBDome), and research work of AAK and BS is funded by DFG SFB1340-TPB06. MFN reports research grants and/or personal fees from Abbvie, MSD, Takeda, Boehringer, Roche, Pfizer, Janssen, Pentax and PPD. BS has served as a consultant for Abbvie, Arena, BMS, Boehringer, Celgene, Falk, Galapagos, Janssen, Lilly, Pfizer, Prometheus, Takeda and has received speaker's fees from Abbvie, CED Service GmbH, Falk, Ferring, Janssen, Novartis, Pfizer, and Takeda as a representative of Charité – Universitätsmedizin Berlin., (© 2022 The Authors.)

Immunosuppressive Interleukin (IL)-10 production by pro-inflammatory CD4 + T cells is a central self-regulatory function to limit aberrant inflammation. Still, the molecular mediators controlling IL-10 expression in human CD4 + T cells are largely undefined. Here, we identify a Notch/STAT3 signaling-module as a universal molecular switch to induce IL-10 expression across human naïve and major effector CD4 + T cell subsets. IL-10 induction was transient, jointly controlled by the transcription factors Blimp-1/c-Maf and accompanied by upregulation of several co-inhibitory receptors, including LAG-3, CD49b, PD-1, TIM-3 and TIGIT. Consistent with a protective role of IL-10 in inflammatory bowel diseases (IBD), effector CD4 + T cells from Crohn's disease patients were defective in Notch/STAT3-induced IL-10 production and skewed towards an inflammatory Th1/17 cell phenotype. Collectively, our data identify a Notch/STAT3-Blimp-1/c-Maf axis as a common anti-inflammatory pathway in human CD4 + T cells, which is defective in IBD and thus may represent an attractive therapeutic target., (© 2022. The Author(s).)

Background: While MR enterography allows detection of inflammatory bowel disease (IBD), the findings continue to be of limited use in guiding treatment-medication vs. surgery., Purpose: To test the feasibility of MR elastography of the gut in healthy volunteers and IBD patients., Study Type: Prospective pilot., Population: Forty subjects (healthy volunteers: n = 20, 37 ± 14 years, 10 women; IBD patients: n = 20 (ulcerative colitis n = 9, Crohn's disease n = 11), 41 ± 15 years, 11 women)., Field Strength/sequence: Multifrequency MR elastography using a single-shot spin-echo echo planar imaging sequence at 1.5 T with drive frequencies of 40, 50, 60, and 70 Hz., Assessment: Maps of shear-wave speed (SWS, in m/s) and loss angle (φ, in rad), representing stiffness and solid-fluid behavior, respectively, were generated using tomoelastography data processing. Histopathological analysis of surgical specimens was used as reference standard in patients., Statistical Tests: Unpaired t-test, one-way analysis of variance followed by Tukey post hoc analysis, Pearson's correlation coefficient and area under the receiver operating characteristic curve (AUC) with 95%-confidence interval (CI). Significance level of 5%., Results: MR elastography was feasible in all 40 subjects (100% technical success rate). SWS and φ were significantly increased in IBD by 21% and 20% (IBD: 1.45 ± 0.14 m/s and 0.78 ± 0.12 rad; healthy volunteers: 1.20 ± 0.14 m/s and 0.65 ± 0.06 rad), whereas no significant differences were found between ulcerative colitis and Crohn's disease (P = 0.74 and 0.90, respectively). In a preliminary assessment, a high diagnostic accuracy in detecting IBD was suggested by an AUC of 0.90 (CI: 0.81-0.96) for SWS and 0.84 (CI: 0.71-0.95) for φ., Data Conclusion: In this pilot study, our results demonstrated the feasibility of MR elastography of the gut and showed an excellent diagnostic performance in predicting IBD., Evidence Level: 1 TECHNICAL EFFICACY: Stage 1., (© 2021 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

A newly developed UVC LED source with an emission wavelength of 233 nm was proved on bactericidal efficacy and skin tolerability. The bactericidal efficacy was qualitatively analysed using blood agar test. Subsequently, quantitative analyses were performed on germ carrier tests using the MRSA strain DSM11822, the MSSA strain DSM799, S. epidermidis DSM1798 with various soil loads. Additionally, the compatibility of the germicidal radiation doses on excised human skin and reconstructed human epidermis was proved. Cell viability, DNA damage and production of radicals were assessed in comparison to typical UVC radiation from discharge lamps (222 nm, 254 nm) and UVB (280-380 nm) radiation for clinical assessment. At a dose of 40 mJ/cm 2 , the 233 nm light source reduced the viable microorganisms by a log 10 reduction (LR) of 5 log 10 levels if no soil load was present. Mucin and protein containing soil loads diminished the effect to an LR of 1.5-3.3. A salt solution representing artificial sweat (pH 8.4) had only minor effects on the reduction. The viability of the skin models was not reduced and the DNA damage was far below the damage evoked by 0.1 UVB minimal erythema dose, which can be regarded as safe. Furthermore, the induced damage vanished after 24 h. Irradiation on four consecutive days also did not evoke DNA damage. The radical formation was far lower than 20 min outdoor visible light would cause, which is classified as low radical load and can be compensated by the antioxidant defence system., (© 2022. The Author(s).)

Cholangiocarcinoma (CCA) is a heterogeneous malignancy with a dismal prognosis. Therapeutic options are largely limited to surgery and conventional chemotherapy offers limited benefit. As immunotherapy has proven highly effective in various cancer types, we have undertaken a quantitative immunohistopathological assessment of immune cells expressing the immunoinhibitory T cell immune response cDNA 7 receptor (TIRC7), an emerging immunoinhibitory receptor, in a cohort of 135 CCA patients. TIRC7 + immune cells were present in both the tumor epithelia and stroma in the majority of CCA cases with the highest levels found in intrahepatic CCA. While intraepithelial density of TIRC7 + immune cells was decreased compared to matched non-neoplastic bile ducts, stromal quantity was higher in the tumor samples. Tumors exhibiting signet ring cell or adenosquamous morphology were exclusively associated with an intraepithelial TIRC7 + phenotype. Survival analysis showed intraepithelial TIRC7 + immune cell density to be a highly significant favorable prognosticator in intrahepatic but not proximal or distal CCA. Furthermore, intraepithelial TIRC7 + immune cell density correlated with the number of intraepithelial CD8 + immune cells and with the total number of CD4 + immune cells. Our results suggest the presence and prognostic relevance of TIRC7 + immune cells in CCA and warrant further functional studies on its pharmacological modulation.

Immunomodulation of airway hyperreactivity by excretory-secretory (ES) products of the first larval stage (L1) of the gastrointestinal nematode Trichuris suis is reported by us and others. Here, we aimed to identify the proteins accounting for the modulatory effects of the T. suis L1 ES proteins and studied six selected T. suis L1 proteins for their immunomodulatory efficacy in a murine OVA-induced allergic airway disease model. In particular, an enzymatically active T. suis chitinase mediated amelioration of clinical signs of airway hyperreactivity, primarily associated with suppression of eosinophil recruitment into the lung, the associated chemokines, and increased numbers of RELM α + interstitial lung macrophages. While there is no indication of T. suis chitinase directly interfering with dendritic cell activation or antigen presentation to CD4 T cells, treatment of allergic mice with the worm chitinase influenced the hosts' own chitinase activity in the inflamed lung. The three-dimensional structure of the T. suis chitinase as determined by high-resolution X-ray crystallography revealed high similarities to mouse acidic mammalian chitinase (AMCase) but a unique ability of T. suis chitinase to form dimers. Our data indicate that the structural similarities between the parasite and host chitinase contribute to the disease-ameliorating effect of the helminth-derived chitinase on allergic lung inflammation., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2021 Friederike Ebner et al.)

The SARS-CoV-2 pandemic has so far claimed over three and a half million lives worldwide. Though the SARS-CoV-2 mediated disease COVID-19 has first been characterized by an infection of the upper airways and the lung, recent evidence suggests a complex disease including gastrointestinal symptoms. Even if a direct viral tropism of intestinal cells has recently been demonstrated, it remains unclear, whether gastrointestinal symptoms are caused by direct infection of the gastrointestinal tract by SARS-CoV-2 or whether they are a consequence of a systemic immune activation and subsequent modulation of the mucosal immune system. To better understand the cause of intestinal symptoms we analyzed biopsies of the small intestine from SARS-CoV-2 infected individuals. Applying qRT-PCR and immunohistochemistry, we detected SARS-CoV-2 RNA and nucleocapsid protein in duodenal mucosa. In addition, applying imaging mass cytometry and immunohistochemistry, we identified histomorphological changes of the epithelium, which were characterized by an accumulation of activated intraepithelial CD8 + T cells as well as epithelial apoptosis and subsequent regenerative proliferation in the small intestine of COVID-19 patients. In summary, our findings indicate that intraepithelial CD8 + T cells are activated upon infection of intestinal epithelial cells with SARS-CoV-2, providing one possible explanation for gastrointestinal symptoms associated with COVID-19., (© 2021. The Author(s).)

Work from the last years indicates that the extracellular matrix (ECM) plays a direct role in various cellular processes, including proliferation, migration and differentiation. Besides homeostatic processes, its regulatory function in inflammation becomes more and more evident. In inflammation, such as inflammatory bowel disease, the ECM composition is constantly remodeled, and this can result in a structuring of fistulizing disease course. Thus, tracking early ECM changes might bear the potential to predict the disease course. In this review, we provide an overview of relevant diagnostic methods, focusing on ECM changes.

Background and Aims: Histological scoring plays a key role in the assessment of disease activity in ulcerative colitis [UC] and is also important in Crohn´s disease [CD]. Currently, there is no common scoring available for UC and CD. We aimed to validate the Inflammatory Bowel Disease [IBD]-Distribution [D], Chronicity [C], Activity [A] score [IBD-DCA score] for histological disease activity assessment in IBD., Methods: Inter- and intra-rater reliability were assessed by 16 observers on biopsy specimens from 59 patients with UC and 25 patients with CD. Construct validity and responsiveness to treatment were retrospectively evaluated in a second cohort of 30 patients., Results: Inter-rater reliability was moderate to good for the UC cohort (intraclass correlation coefficients [ICCs] = 0.645, 0.623, 0.767 for D, C, and A, respectively) and at best moderate for the CD cohort [ICC = 0.690, 0.303, 0.733 for D, C, and A, respectively]. Intra-rater agreement ranged from good to excellent in both cohorts. Correlation with the Nancy Histological Index [NHI] was moderate and strong with the Simplified Geboes Score [SGS] and a Visual Analogue Scale [VAS], respectively. Large effect sizes were obtained for all three parameters. External responsiveness analysis revealed correlated changes between IBD-DCA score and NHI, SGS and VAS., Conclusions: The IBD-DCA score is a simple histological activity score for UC and CD, agreed and validated by a large group of IBD specialists. It provides reliable information on treatment response. Therefore, it has potential value for use in routine diagnostics as well as clinical studies., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation.)

Background: Tissue-resident memory T (T RM ) cells are known to be important for the first line of defense in mucosa-associated tissues. However, the composition, localization, effector function, and specificity of T RM cells in the human kidney and their relevance for renal pathology have not been investigated., Methods: Lymphocytes derived from blood, renal peritumor samples, and tumor samples were phenotypically and functionally assessed by applying flow cytometry and highly advanced histology (multi-epitope ligand cartography) methods., Results: CD69 + CD103 + CD8 + T RM cells in kidneys display an inflammatory profile reflected by enhanced IL-2, IL-17, and TNF α production, and their frequencies correlate with increasing age and kidney function. We further identified mucosa-associated invariant T and CD56 dim and CD56 bright natural killer cells likewise expressing CD69 and CD103, the latter significantly enriched in renal tumor tissues. CD8 + T RM cell frequencies were not elevated in kidney tumor tissue, but they coexpressed PD-1 and TOX and produced granzyme B. Tumor-derived CD8 + T RM cells from patients with metastases were functionally impaired. Both CD69 + CD103 - CD4 + and CD69 + CD103 - CD8 + T RM cells form distinct clusters in tumor tissues in proximity to antigen-presenting cells. Finally, EBV, CMV, BKV, and influenza antigen-specific CD8 + T cells were enriched in the effector memory T cell population in the kidney., Conclusions: Our data provide an extensive overview of T RM cells' phenotypes and functions in the human kidney for the first time, pointing toward their potential relevance in kidney transplantation and kidney disease., (Copyright © 2021 by the American Society of Nephrology.)

Inflammatory bowel diseases (IBD) are characterized by chronic dysregulation of immune homeostasis, epithelial demise, immune cell activation, and microbial translocation. Each of these processes leads to proinflammatory changes via the release of cytokines, damage-associated molecular patterns (DAMPs), and pathogen-associated molecular patterns (PAMPs), respectively. The impact of these noxious agents on the survival and function of the enteric nervous system (ENS) is poorly understood. Here, we show that in contrast to an expected decrease, experimental as well as clinical colitis causes an increase in the transcript levels of enteric neuronal and glial genes. Immunostaining revealed an elevated neuronal innervation of the inflamed regions of the gut mucosa. The increase was seen in models with overt damage to epithelial cells and models of T cell-induced colitis. Transcriptomic data from treatment naïve pediatric IBD patients also confirmed the increase in the neuroglial genes and were replicated on an independent adult IBD dataset. This induction in the neuroglial genes was transient as levels returned to normal upon the induction of remission in both mouse models as well as colitis patients. Our data highlight the dynamic and robust nature of the enteric nervous system in colitis and open novel questions on its regulation.

Neuroinflammatory processes occurring during multiple sclerosis cause disseminated softening of brain tissue, as quantified by in vivo magnetic resonance elastography (MRE). However, inflammation-mediated tissue alterations underlying the mechanical integrity of the brain remain unclear. We previously showed that blood-brain barrier (BBB) disruption visualized by MRI using gadolinium-based contrast agent (GBCA) does not correlate with tissue softening in active experimental autoimmune encephalomyelitis (EAE). However, it is unknown how confined BBB changes and other inflammatory processes may determine local elasticity changes. Therefore, we aim to elucidate which inflammatory hallmarks are determinant for local viscoelastic changes observed in EAE brains. Hence, novel multifrequency MRE was applied in combination with GBCA-based MRI or very small superparamagnetic iron oxide particles (VSOPs) in female SJL mice with induced adoptive transfer EAE ( n = 21). VSOPs were doped with europium (Eu-VSOPs) to facilitate the post-mortem analysis. Accumulation of Eu-VSOPs, which was previously demonstrated to be sensitive to immune cell infiltration and ECM remodeling, was also found to be independent of GBCA enhancement. Following registration to a reference brain atlas, viscoelastic properties of the whole brain and areas visualized by either Gd or VSOP were quantified. MRE revealed marked disseminated softening across the whole brain in mice with established EAE (baseline: 3.1 ± 0.1 m/s vs. EAE: 2.9 ± 0.2 m/s, p < 0.0001). A similar degree of softening was observed in sites of GBCA enhancement i.e., mainly within cerebral cortex and brain stem (baseline: 3.3 ± 0.4 m/s vs. EAE: 3.0 ± 0.5 m/s, p = 0.018). However, locations in which only Eu-VSOP accumulated, mainly in fiber tracts (baseline: 3.0 ± 0.4 m/s vs. EAE: 2.6 ± 0.5 m/s, p = 0.023), softening was more pronounced when compared to non-hypointense areas (percent change of stiffness for Eu-VSOP accumulation: -16.81 ± 16.49% vs. for non-hypointense regions: -5.85 ± 3.81%, p = 0.048). Our findings suggest that multifrequency MRE is sensitive to differentiate between local inflammatory processes with a strong immune cell infiltrate that lead to VSOP accumulation, from disseminated inflammation and BBB leakage visualized by GBCA. These pathological events visualized by Eu-VSOP MRI and MRE may include gliosis, macrophage infiltration, alterations of endothelial matrix components, and/or extracellular matrix remodeling. MRE may therefore represent a promising imaging tool for non-invasive clinical assessment of different pathological aspects of neuroinflammation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Silva, Morr, Mueller, Koch, Boehm-Sturm, Rodriguez-Sillke, Kunkel, Tzschätzsch, Kühl, Schnorr, Taupitz, Sack and Infante-Duarte.)

Background: Microbial colonization and immune cell maturation coincide at mucosal sites and are decisive for postnatal lung development. How external factors influence neonatal pulmonary immune development is poorly understood., Objective: To elucidate the impact of key determinants in early life, nutrition, and maternal bonding, on postnatal lung maturation in a human-relevant animal model. To investigate the underlying immunological changes of impaired lung maturation and study the mechanisms of conversion., Methods: Newborn piglets were kept with or without isolation from their mothers and fed bovine milk-based infant formula or received milk of sow. Lung growth, histomorphology, respiratory immune responses, and lung microbiota were analyzed. Mother- and sow-milk-deprived piglets received maternal material or were reintroduced to the maternal environment at varying intervals to study options for reversal., Results: Formula feeding combined with isolation of newborn piglets resulted in disturbed postnatal lung maturation. Reduced lung growth correlated with dampened IL-33 expression, impaired lung myeloid cell activation, and decreased Th1 differentiation, along with diminished richness and diversity of the lung microbiota. Transfer of bacteria-enriched maternal material reversed the negative effects on pulmonary immune maturation. Early (within 3 days) but not late (within 7 days) reintroduction to the mother allowed restoration of normal lung development., Conclusion: Our findings reveal that lung growth, respiratory immunity, and microbial lung colonization in newborns depend on postnatal diet and maternal contact, and targeting these key regulators could promote lung development during this critical life stage., Summary: Disturbances in natural diet and reduced maternal contact during the neonatal period impair postnatal lung maturation. In pediatrics, timely breast milk feeding and intensive maternal bonding represent valuable intervention measures to promote early postnatal lung development., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Schlosser-Brandenburg, Ebner, Klopfleisch, Kühl, Zentek, Pieper and Hartmann.)

Structural changes of soft tissues on the cellular level can be characterized by histopathology, but not longitudinally in the same tissue. Alterations of cellular structures and tissue matrix are associated with changes in biophysical properties which can be monitored longitudinally by quantitative diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE). In this work, DWI and MRE examinations were performed in a 0.5-Tesla compact scanner to investigate longitudinal changes in water diffusivity, stiffness and viscosity of ex-vivo rat livers for up to 20 h post-mortem (pm). The effect of blood on biophysical parameters was examined in 13 non-perfused livers (containing blood, NPLs) and 14 perfused livers (blood washed out, PLs). Changes in cell shape, cell packing and cell wall integrity were characterized histologically. In all acquisitions, NPLs presented with higher shear-wave speed (c) , higher shear-wave penetration rate (a) and smaller apparent-diffusion-coefficients (ADCs) than PL. Time-resolved analysis revealed three distinct phases: (i) an initial phase (up to 2 h pm) with markedly increased c and a and reduced ADCs; (ii) an extended phase with relatively stable values; and (iii) a degradation phase characterized by significant increases in a (10 h pm in NPLs and PLs) and ADCs (10 h pm in NPLs, 13 h pm in PLs). Histology revealed changes in cell shape and packing along with decreased cell wall integrity, indicating tissue degradation in NPLs and PLs 10 h pm. Taken together, our results demonstrate that the biophysical properties of fresh liver tissue rapidly change within 2 h pm, which seems to be an effect of both cytotoxic edema and vascular blood content. Several hours later, disruption of cell walls resulted in higher water diffusivity and wave penetration. These results reveal the individual contributions of vascular components and cellular integrity to liver elastography and provide a biophysical, imaging-based fingerprint of liver tissue degradation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Garczyńska, Tzschätzsch, Assili, Kühl, Häckel, Schellenberger, Berndt, Holzhütter, Braun, Sack and Guo.)

Inflammatory bowel diseases present with elevated levels of intestinal epithelial cell (IEC) death, which compromises the gut barrier, activating immune cells and triggering more IEC death. The endogenous signals that prevent IEC death and break this vicious cycle, allowing resolution of intestinal inflammation, remain largely unknown. Here we show that prostaglandin E2 signalling via the E-type prostanoid receptor 4 (EP4) on IECs represses epithelial necroptosis and induces resolution of colitis. We found that EP4 expression correlates with an improved IBD outcome and that EP4 activation induces a transcriptional signature consistent with resolution of intestinal inflammation. We further show that dysregulated necroptosis prevents resolution, and EP4 agonism suppresses necroptosis in human and mouse IECs. Mechanistically, EP4 signalling on IECs converges on receptor-interacting protein kinase 1 to suppress tumour necrosis factor-induced activation and membrane translocation of the necroptosis effector mixed-lineage kinase domain-like pseudokinase. In summary, our study indicates that EP4 promotes the resolution of colitis by suppressing IEC necroptosis., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

For in vitro modeling of human joints, osteochondral explants represent an acceptable compromise between conventional cell culture and animal models. However, the scarcity of native human joint tissue poses a challenge for experiments requiring high numbers of samples and makes the method rather unsuitable for toxicity analyses and dosing studies. To scale their application, we developed a novel method that allows the preparation of up to 100 explant cultures from a single human sample with a simple setup. Explants were cultured for 21 days, stimulated with TNF-α or TGF-β3, and analyzed for cell viability, gene expression and histological changes. Tissue cell viability remained stable at >90% for three weeks. Proteoglycan levels and gene expression of COL2A1 , ACAN and COMP were maintained for 14 days before decreasing. TNF-α and TGF-β3 caused dose-dependent changes in cartilage marker gene expression as early as 7 days. Histologically, cultures under TNF-α stimulation showed a 32% reduction in proteoglycans, detachment of collagen fibers and cell swelling after 7 days. In conclusion, thin osteochondral slice cultures behaved analogously to conventional punch explants despite cell stress exerted during fabrication. In pharmacological testing, both the shorter diffusion distance and the lack of need for serum in the culture suggest a positive effect on sensitivity. The ease of fabrication and the scalability of the sample number make this manufacturing method a promising platform for large-scale preclinical testing in joint research.

Increasing evidence suggests male sex as a potential risk factor for a higher incidence of cardiac fibrosis, stronger cardiac inflammation, and dilated cardiomyopathy (DCM) in human myocarditis. Chronic activation of the immune response in myocarditis may trigger autoimmunity. The experimental autoimmune myocarditis (EAM) model has been well established for the study of autoimmune myocarditis, however the role of sex in this pathology has not been fully explored. In this study, we investigated sex differences in the inflammatory response in the EAM model. We analyzed the cardiac function, as well as the inflammatory stage and fibrosis formation in the heart of EAM male and female rats. 21 days after induction of EAM, male EAM rats showed a decreased ejection fraction, stroke volume and cardiac output, while females did not. A significantly elevated number of infiltrates was detected in myocardium in both sexes, indicating the activation of macrophages following EAM induction. The level of anti-inflammatory macrophages (CD68+ ArgI+) was only significantly increased in female hearts. The expression of Col3A1 and fibrosis formation were more prominent in males. Furthermore, prominent pro-inflammatory factors were increased only in male rats. These findings indicate sex-specific alterations in the inflammatory stage of EAM, with a pro-inflammatory phenotype appearing in males and an anti-inflammatory phenotype in females, which both significantly affect cardiac function in autoimmune myocarditis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Barcena, Jeuthe, Niehues, Pozdniakova, Haritonow, Kühl, Messroghli and Regitz-Zagrosek.)

Background & Aims: A substantial proportion patients with inflammatory bowel disease (IBD) have a primary non-response to infliximab; markers are needed to identify patients most likely to respond to treatment. We investigated whether production of tumor necrosis factor (TNF) by peripheral blood mononuclear cells (PBMCs) can be used as a marker to predict response., Methods: We performed a prospective study of 41 adults with IBD (mean age, 38 years; 21 male; 21 with Crohn's disease and 20 with ulcerative colitis) not treated with a biologic agent within the past 6 months; patients were given their first infusion of infliximab at a hospital or clinic in Berlin, Germany. We collected data on clinical scores, levels of C-reactive protein, and ultrasound results (Limberg scores) at baseline (before the first infusion) and after 6 weeks (3 rd infliximab infusion). PMBCs were obtained from patients at baseline and 10 healthy individuals (controls) and incubated with lipopolysaccharide. We measured production of cytokines (TNF, interleukin 1 [IL1], IL6, IL8, IL10, IL12p70, and IL22) by ELISA and performed cytometric bead array and flow cytometry analyses. The primary endpoint was clinical response (decrease in Harvey Bradshaw Index scores of 2 or more or decrease in partial Mayo scores of 3 or more at week 6) in patients with PBMCs that produced high vs low levels of TNF., Results: Responders had a shorter median disease duration (P = .018) and higher median Limberg score (P = .021), than nonresponders. Baseline PBMCs from responders produced significantly more TNF (P = .049) and IL6 (P = .028) than from nonresponders; a level of 500 pg/ml TNF identified responders with 82% sensitivity and 78% specificity. In patients with Crohn's disease, this cutoff value (500 pg/ml TNF) identified responders with 100% sensitivity and 82% specificity; TNF levels above this level were independently associated with response to infliximab in multivariate analysis (odds ratio, 16.2; 95% CI, 1.8-148.7; P = .014). The percentage of TNF-positive cells was higher among CD14+ monocytes than lymphocytes after stimulation., Conclusions: Production of a high level of TNF by PBMCs (specifically CD14+ cells) from patients with IBD can identify those most likely to have a clinical response to infliximab therapy. In patients with Crohn's disease, a cutoff value of 500 pg/ml TNF identified responders with 100% sensitivity and 82% specificity., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Molecular evidence of cellular heterogeneity in the human exocrine pancreas has not been yet established because of the local concentration and cascade of hydrolytic enzymes that can rapidly degrade cells and RNA upon pancreatic resection. We sought to better understand the heterogeneity and cellular composition of the pancreas in neonates and adults in healthy and diseased conditions using single-cell sequencing approaches., Methods: We innovated single-nucleus RNA-sequencing protocols and profiled more than 120,000 cells from pancreata of adult and neonatal human donors. We validated the single-nucleus findings using RNA fluorescence in situ hybridization, in situ sequencing, and computational approaches., Results: We created the first comprehensive atlas of human pancreas cells including epithelial and nonepithelial constituents, and uncovered 3 distinct acinar cell types, with possible implications for homeostatic and inflammatory processes of the pancreas. The comparison with neonatal single-nucleus sequencing data showed a different cellular composition of the endocrine tissue, highlighting the tissue dynamics occurring during development. By applying spatial cartography, involving cell proximity mapping through in situ sequencing, we found evidence of specific cell type neighborhoods, dynamic topographies in the endocrine and exocrine pancreas, and principles of morphologic organization of the organ. Furthermore, similar analyses in chronic pancreatitis biopsy samples showed the presence of acinar-REG + cells, a reciprocal association between macrophages and activated stellate cells, and a new potential role of tuft cells in this disease., Conclusions: Our human pancreas cell atlas can be interrogated to understand pancreatic cell biology and provides a crucial reference set for comparisons with diseased tissue samples to map the cellular foundations of pancreatic diseases., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: IgA and Th17 responses are pivotal for the control of Giardia infections. Eosinophils support IgA class switching, the survival of intestinal IgA + plasma cells at steady state and can control Th17 activity in the small intestine. To see whether eosinophils regulate adaptive immune responses during giardiasis, we investigated Giardia muris infections in wild-type BALB/c and eosinophil-deficient ∆dblGATA-1 mice., Methods and Results: Infected ∆dblGATA-1 mice did not differ markedly in parasite control from wild-type mice. Confirming previous studies, naive ∆dblGATA-1 mice displayed diminished IgA + B cell frequencies in Peyer's patches. However, IgA class switching and intestinal IgA secretion in response to G muris infection were comparable in wild-type BALB/c and ∆dblGATA-1 mice. Both strains displayed similarly low intestinal Th17 responses, accompanied by a mild expansion of type 3 innate lymphoid cells (ILC3)., Conclusions: Contrasting previous reports on overt small intestinal Th17 activity in eosinophil-deficient mice, IL-17A production is kept in check in the absence of eosinophils during Giardia infection. Suboptimal homeostatic IgA responses in the absence of eosinophils are transiently fostered in infected mice and the maintenance of IgA + plasma cells appears to be restored during persisting Giardia infection., (© 2020 The Authors. Parasite Immunology published by John Wiley & Sons Ltd.)

Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor (SSTR) analogs is a common approach in advanced neuroendocrine neoplasms. Recently, SSTR antagonists have shown promising results for imaging and therapy due to a higher number of binding sites than in commonly used agonists. We evaluated PRRT with SSTR agonist 177 Lu-DOTATOC and antagonist 177 Lu-DOTA-JR11 longitudinally in an orthotopic murine pancreatic neuroendocrine neoplasm model expressing human SSTR2. Morphologic and metabolic changes during treatment were assessed using multimodal imaging, including hybrid PET/MRI and SPECT/CT. Methods: In vitro radioligand binding and internalization assays and cell-cycle analysis were performed. SSTR2-transfected BON cells (BON-SSTR2) were used for in vivo experiments. Tumor-bearing mice received 2 intravenous injections of 100 μL of saline, 30 MBq of 177 Lu-DOTATOC, or 20 MBq of 177 Lu-DOTA-JR11 with an interval of 3 wk. Weekly T2-weighted MRI was performed for tumor monitoring. Viability of the tumor tissue was assessed by 18 F-FDG PET/MRI once after PRRT. Tumor and kidney uptake of the respective radiopharmaceuticals was measured 24 h after injection by SPECT/CT. Results: Compared with 177 Lu-DOTATOC, 177 Lu-DOTA-JR11 treatment resulted in an increased accumulation of cells in G2/M phase. Animals treated with the SSTR antagonist showed a significant reduction in tumor size ( P < 0.001) and an increased median survival (207 d; interquartile range [IQR], 132-228) compared with 177 Lu-DOTATOC (126 d; IQR, 118-129). SPECT/CT revealed a 4-fold higher median tumor uptake for the antagonist and a 3-fold higher tumor-to-kidney ratio in the first treatment cycle. During the second therapy cycle, tumor uptake of 177 Lu-DOTATOC was significantly lower ( P = 0.01) whereas 177 Lu-DOTA-JR11 uptake remained stable. Imaging of tumor morphology indicated comparatively larger necrotic fractions for 177 Lu-DOTA-JR11 despite further tumor growth. These results were confirmed by 18 F-FDG PET, revealing the least amount of viable tumor tissue in 177 Lu-DOTA-JR11-treated animals, at 6.2% (IQR, 2%-23%). Conclusion: 177 Lu-DOTA-JR11 showed a higher tumor-to-kidney ratio and a more pronounced cytotoxic effect than did 177 Lu-DOTATOC. Additionally, tumor uptake was more stable over the course of 2 treatment cycles., (© 2021 by the Society of Nuclear Medicine and Molecular Imaging.)