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Background: Human adenovirus type 7 (HAdV7) has become a major public health threat due to its widespread transmission, severe associated pneumonia, and a lack of effective anti-HAdV7 drugs. The aim of the current study is to design a humanized monoclonal antibody (mAb) demonstrating efficacy against HAdV-7 infections in vitro and in vivo. Methods: The humanized neutralizing antibody, 3G5-hu, was derived from the murine mAb 3G5. Antibody activity was evaluated using a flow cytometry-based neutralization (FCN) assay to identify humanized mAbs retaining potent neutralizing activity. Additionally, a humanized hDSG2/hCD46 dual-receptor transgenic mouse model was developed to simulate HAdV-7 infection. Results: Using recombinant HAdV-7 expressing enhanced green fluorescent protein and clinically isolated wild-type HAdV-7, the half-maximal effective concentration of 3G5-hu against HAdV-7 was determined to be < 30 ng/mL. Notably, 3G5-hu exhibits high specificity for the hexon protein of the HAdV-7 capsid (affinity: KD = 9.02 × 10− 11 M). Microneutralization studies with wild-type HAdV-7 and rAd7EGFP confirmed that humanized mAb 3G5-hu neutralizes 10–30 ng/mL HAdV-7 (approximately 67–200 pM). Furthermore, hDSG2/hCD46 double-receptor transgenic mice are more susceptible to HAdV-7 infection than single-receptor transgenic mice. Meanwhile, the humanized mAb 3G5-hu provides good protection against HAdV-7 infection in hDSG2/hCD46 knock-in transgenic mice. Conclusions: The newly designed humanized mAb 3G5-hu specifically neutralizes HAdV-7 in vitro and in vivo. 3G5-hu elicits protection against HAdV-7 infection in hDSG2/hCD46 knock-in transgenic mice. The findings of this study provide insights to guide the future development of preventative and therapeutic treatments for HAdV-7 infection. [ABSTRACT FROM AUTHOR]

Background: Pemphigus vulgaris (PV) is a life-threatening autoimmune blistering disease caused mainly by IgG autoantibodies (auto-abs) against the cadherintype adhesion molecules desmoglein (Dsg) 1 and 3. Pathogenic anti-Dsg3 autoabs bind to different Dsg3 epitopes, leading, among others, to signalling that is involved in pathogenic events, such as Dsg3 depletion. As central tools in research on PV, a limited number of antibodies such as AK23 are frequently used by the autoimmune bullous disease community. Methods: Previously, we have introduced a novel Dsg3 EC5-binding antibody termed 2G4 that may potentially serve as a superior tool for numerous PV related analysis. The purpose of this study was to develop a quality-controlled production and verification process that allows I) a continuous quality improvement, and II) a verified and comprehensible overall quality with regard to pathogenic antigenspecific binding in a variety of pemphigus assays for each batch production. Results: Thus, a workflow based on a standardized operating procedure was established. This includes the verification of purity and in-vitro binding capacity (SDS-page, direct and indirect immunofluorescence) as primary parameters, and size analysis by mass-spectrometry and ex-vivo pathogenicity by monolayer dissociation assay. Conclusion: We here present an extensive point-by-point quality controlled IgG production protocol, which will serve as a basis for a standardized antibody assessment in PV research. [ABSTRACT FROM AUTHOR]

Cadherins are calcium dependent adhesion proteins that establish and maintain the intercellular mechanical contact by bridging the gap between adjacent cells. Desmoglein-2 (Dsg2) and desmocollin-2 (Dsc2) are tissue specific cadherin isoforms of the cell-cell contact in cardiac desmosomes. Mutations in the DSG2 -gene and in the DSC2 -gene are related to arrhythmogenic right ventricular cardiomyopathy (ARVC) a rare but severe heart muscle disease. Here, several possible homophilic and heterophilic binding interactions of wild-type Dsg2, wild-type Dsc2, as well as one Dsg2- and two Dsc2-variants, each associated with ARVC, are investigated. Using single molecule force spectroscopy (SMFS) with atomic force microscopy (AFM) and applying Jarzynski's equality the kinetics and thermodynamics of Dsg2/Dsc2 interaction can be determined. The free energy landscape of Dsg2/Dsc2 dimerization exposes a high activation energy barrier, which is in line with the proposed strand-swapping binding motif. Although the binding motif is not affected by any of the mutations, the binding kinetics of the interactions differ significantly from the wild-type. While wild-type cadherins exhibit an average complex lifetime of approx. 0.3 s interactions involving a variant consistently show - lifetimes that are substantially larger. The lifetimes of the wild-type interactions give rise to the picture of a dynamic adhesion interface consisting of continuously dissociating and (re)associating molecular bonds, while the delayed binding kinetics of interactions involving an ARVC-associated variant might be part of the pathogenesis. Our data provide a comprehensive and consistent thermodynamic and kinetic description of cardiac cadherin binding, allowing detailed insight into the molecular mechanisms of cell adhesion. [Display omitted] • Integrity of heart muscle tissue relies on weak molecular bonds between cadherins. • Single molecule force spectroscopy reveals cadherin binding kinetics. • Wild-type cadherin bonds exhibit characteristic fast (re-) binding kinetics. • Specific cardiomyopathy associated cadherin variants slow binding kinetics. • Impaired molecular dynamics could be a cardiomyopathy-specific pathomechanism. [ABSTRACT FROM AUTHOR]

Cell-cell junctions, and specifically desmosomes, are crucial for robust intercellular adhesion. Desmosomal function is compromised in the autoimmune blistering skin disease pemphigus vulgaris. We combine whole-genome knockout screening and a promotor screen of the desmosomal gene desmoglein 3 in human keratinocytes to identify novel regulators of intercellular adhesion. Kruppel-like-factor 5 (KLF5) directly binds to the desmoglein 3 regulatory region and promotes adhesion. Reduced levels of KLF5 in patient tissue indicate a role in pemphigus vulgaris. Autoantibody fractions from patients impair intercellular adhesion and reduce KLF5 levels in in vitro and in vivo disease models. These effects were dependent on increased activity of histone deacetylase 3, leading to transcriptional repression of KLF5. Inhibiting histone deacetylase 3 increases KLF5 levels and protects against the deleterious effects of autoantibodies in murine and human pemphigus vulgaris models. Together, KLF5 and histone deacetylase 3 are regulators of desmoglein 3 gene expression and intercellular adhesion and represent potential therapeutic targets in pemphigus vulgaris. Cell-cell adhesion by desmosomes is weakened in the blistering skin disease pemphigus vulgaris. Here, authors found that the transcription factor Kruppel-like factor 5 is essential for the expression of the desmosomal gene desmoglein 3 and suggest a novel treatment approach. [ABSTRACT FROM AUTHOR]

Autoimmune blistering diseases of the pemphigus and pemphigoid groups are immune-mediated disorders due to circulating pathogenetic autoantibodies. Multiple human leukocyte antigen (HLA) genes have been associated with predisposition to these disorders. HLA-Cw6 is involved in antigen presentation processes and has been linked to psoriasis. The aim of our study was to investigate the association between the presence of the HLA-Cw6 allele and susceptibility to pemphigus vulgaris and bullous pemphigoid. A genetic study in vitro with a cross-sectional design was performed enrolling forty patients with pemphigus vulgaris and forty patients with bullous pemphigoid. The detection of HLA-Cw6 was performed through the EUROArray test on DNA obtained from whole blood samples. The polymorphism was detected in 3/40 genotypes in the pemphigus vulgaris group and in 4/40 genotypes of patients with bullous pemphigoid, unveiling a non-statistically significant different frequency in pemphigus (p = 0.6368) and in pemphigoid (p = 0.62) compared to the reference frequency from the literature of 0.086. Further research is needed to better investigate the role of HLA-Cw6 in immune-mediated diseases and to identify novel genetic markers associated with susceptibility to autoimmune blistering diseases and with disease severity and response to immunosuppressive therapies. [ABSTRACT FROM AUTHOR]

This article discusses the potential therapeutic target MKK3 in blister formation in pemphigus, a condition characterized by autoantibody-mediated disruption of keratinocyte adhesion. The study aims to understand the roles of MKK3 and MKK6 in pemphigus and evaluate their inhibition as a treatment approach. Immunohistochemical analysis of skin specimens from pemphigus patients showed pronounced expression of phosphorylated MKK3 and p38 MAPK, indicating their involvement in pemphigus pathogenesis. In vitro studies using an MKK3 inhibitor demonstrated improved cell-cell adhesion and reduced blister formation. Targeting MKK3 may offer a promising alternative treatment option for pemphigus and other autoimmune and inflammatory conditions. [Extracted from the article]

Pemphigus is an autoimmune disease that affects the skin and mucous membranes, induced by the deposition of pemphigus IgG, which mainly targets desmogleins 1 and 3 (Dsg1 and 3). This autoantibody causes steric interference between Dsg1 and 3 and the loss of cell adhesion, producing acantholysis. This molecule and its cellular effects are clinically reflected as intraepidermal blistering. Pemphigus vulgaris-IgG (PV-IgG) binding involves p38MAPK-signaling-dependent caspase-3 activation. The present work assessed the in vitro effect of PV-IgG on the adherence of HaCaT cells dependent on caspase-3. PV-IgG induced cell detachment and apoptotic changes, as demonstrated by annexin fluorescent assays. The effect of caspase-3 induced by PV-IgG was suppressed in cells pre-treated with caspase-3-shRNA, and normal IgG (N-IgG) as a control had no relevant effects on the aforementioned parameters. The results demonstrated that shRNA reduces caspase-3 expression, as measured via qRT-PCR and via Western blot and immunofluorescence, and increases cell adhesion. In conclusion, shRNA prevented in vitro cell detachment and the late effects of apoptosis induced by PV-IgG on HaCaT cells, furthering our understanding of the molecular role of caspase-3 cell adhesion dependence in pemphigus disease. [ABSTRACT FROM AUTHOR]

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and a monogenic cause of autism spectrum disorders. Deficiencies in the fragile X messenger ribonucleoprotein, encoded by the FMR1 gene, lead to various anatomical and pathophysiological abnormalities and behavioral deficits, such as spine dysmorphogenesis and learning and memory impairments. Synaptic cell adhesion molecules (CAMs) play crucial roles in synapse formation and neural signal transmission by promoting the formation of new synaptic contacts, accurately organizing presynaptic and postsynaptic protein complexes, and ensuring the accuracy of signal transmission. Recent studies have implicated synaptic CAMs such as the immunoglobulin superfamily, N-cadherin, leucine-rich repeat proteins, and neuroligin-1 in the pathogenesis of FXS and found that they contribute to defects in dendritic spines and synaptic plasticity in FXS animal models. This review systematically summarizes the biological associations between nine representative synaptic CAMs and FMRP, as well as the functional consequences of the interaction, to provide new insights into the mechanisms of abnormal synaptic development in FXS. [ABSTRACT FROM AUTHOR]

CAR T cell therapy has shown promising results in the treatment of autoimmune diseases. In 2023, five key studies were highlighted that are driving the development of CAR T cells to improve precision, safety, efficacy, and accessibility for the treatment of autoantibody-associated autoimmune diseases. CAR T cells targeting CD19 have been successful in achieving drug-free remission in patients with systemic lupus erythematosus. Other studies have explored the use of CAR T cells targeting B cell maturation antigen (BCMA) and chimeric autoantibody receptor (CAAR) T cells targeting specific autoantibodies in diseases such as neuromyelitis optica spectrum disorder and myasthenia gravis. Additionally, advancements have been made in the use of RNA-based CAR T cells, which offer potential advantages over DNA-based CAR T cells. These developments in precision cellular therapy hold promise for improving outcomes in autoimmune disease treatment. [Extracted from the article]

Background: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with an unpredictable course of recurrent exacerbations alternating with more stable disease. SLE is characterized by broad immune activation and autoantibodies against double-stranded DNA and numerous proteins that exist in cells as aggregates with nucleic acids, such as Ro60, MOV10, and the L1 retrotransposon-encoded ORF1p. Results: Here we report that these 3 proteins are co-expressed and co-localized in a subset of SLE granulocytes and are concentrated in cytosolic dots that also contain DNA: RNA heteroduplexes and the DNA sensor ZBP1, but not cGAS. The DNA: RNA heteroduplexes vanished from the neutrophils when they were treated with a selective inhibitor of the L1 reverse transcriptase. We also report that ORF1p granules escape neutrophils during the extrusion of neutrophil extracellular traps (NETs) and, to a lesser degree, from neutrophils dying by pyroptosis, but not apoptosis. Conclusions: These results bring new insights into the composition of ORF1p granules in SLE neutrophils and may explain, in part, why proteins in these granules become targeted by autoantibodies in this disease. [ABSTRACT FROM AUTHOR]

The cadherin superfamily molecules, functioning as cell adhesion molecules, are recognized to play roles in both physiological and pathological processes. The cadherin-based adherent junction (CAJ) is believed to interact with presenilin-1 (PS-1), suggesting that disruptions in CAJ structures might contribute to neurodegeneration, potentially leading to Alzheimer's Disease (AD). Yet, the specific expression patterns of cadherin superfamily mRNA remain somewhat ambiguous. This research utilized in situ hybridization (ISH) to examine the expression and localization of cadherin mRNA in AD mouse model brains. Long cRNA probes targeting cadherin revealed endogenous mRNA expression in brain sections. Interestingly, senile plaques in the AD mouse brain were also bound to these probes. This binding, however, did not exclusively denote cadherin mRNA, as ISH detected both antisense and sense cRNA probes. Our data suggest that although antisense cRNA probes effectively detected cadherin mRNA expression in AD brain cells, their association with senile plaques may not specifically indicate cadherin mRNA expression. [ABSTRACT FROM AUTHOR]

COVID‐19 tended to be less aggressive in dengue endemic regions. Conversely, dengue cases plummeted in dengue endemic zones during the active years of the pandemic (2020–2021). We and others have demonstrated serological cross‐reactivity between these two viruses of different families. We further demonstrated that COVID‐19 serum samples that were cross‐reactive in dengue virus (DV) serological tests, "cross‐neutralized" all DV serotypes in Huh7 cells. Here we showed by co‐immunoprecipitation (Co‐IP) and atomic force microscopy (AFM) imaging that severe acute respiratory syndrome (SARS)‐coronavirus (CoV)‐2 (SARS‐CoV‐2) spike (S) protein subunit S1 and S2 monoclonal antibodies can indeed, bind to DV particles. Likewise, DV envelope antibodies (DV E Abs) showed high docking frequency with other human pathogenic beta‐CoVs and murine hepatitis virus‐1 (MHV‐1). SARS‐CoV‐2 Ab didn't show docking or Co‐IP with MHV‐1 supporting poor cross‐protection among CoVs. DV E Abs showed binding to MHV‐1 (AFM, Co‐IP, and immunofluorescence) and prepandemic dengue patients' serum samples even "cross‐neutralized" MHV‐1 plaques in cell culture. Furthermore, dengue serum samples showed marked inhibition potential in a surrogate virus‐based competitive enzyme‐linked immunosorbent assay, used for determining neutralizing Abs against SARS‐CoV‐2 S protein receptor‐binding domain in COVID‐19 serum samples. We therefore, provide multiple evidence as to why CoVs are epidemiologically less prevalent in highly dengue endemic regions globally. [ABSTRACT FROM AUTHOR]

Objectives: Anti‐acetylcholine receptor antibodies (AChR Ab) are one of the pathogenic autoantibodies in myasthenia gravis (MG), and they are specifically mentioned in the Japanese clinical guidelines for MG. In the serological diagnosis and measurement of autoantibodies as an adjunct marker for MG, the radioimmunoassay (RIA) method has been conventionally used as the gold standard. However, there have been several worldwide concerns regarding the use of radioisotopes. In this study, we evaluated the performance of the EUROIMMUN AChR Ab enzyme‐linked immunosorbent assay (ELISA) in comparison with RIA. Methods: ELISA reproducibility and dilution linearity were analyzed using AChR Ab‐positive samples. Sera from 50 patients with suspected MG and 50 healthy donors were used to assess the correlation and qualitative agreement between the two methods. Results: The ELISA showed good interassay precision and dilution linearity. The correlation coefficient, sensitivity, specificity and overall agreement of the ELISA in comparison with the conventional RIA amounted to 0.87, 98%, 92% and 95% (kappa = 0.895), respectively. Analysis of the discordant results suggested that the ELISA might be more capable of detecting low AChR Ab reactivity in patients with suspected MG. Conclusions: The AchR Ab ELISA provides a reliable tool for the quantification of AchR Ab, supporting the diagnosis of MG. As a non‐isotopic assay with good precision, shorter handling time and high correlation with the conventional RIA, the AChR ELISA could be a useful alternative in the laboratory routine. [ABSTRACT FROM AUTHOR]

Objectives: The dysregulated immune response is one of the cardinal features of severe coronavirus disease 2019 (COVID‐19). This study was conducted to clarify the occurrence of autoantibodies (AABs) associated with systemic autoimmune rheumatic diseases (SARDs) in hospitalized patients with a moderate, severe, and critical form of COVID‐19. Methods: The serum samples obtained from 176 hospitalized COVID‐19 patients were investigated in this study, including patients with moderate (N = 90), severe (N = 50), and critical (N = 36) forms of COVID‐19. Also, the serum samples collected from healthy subjects before the COVID‐19 pandemic were used as controls (N = 176). The antinuclear antibodies (ANAs), antidouble‐stranded DNA (anti‐dsDNA), cytoplasmic‐anti neutrophil cytoplasmic antibody (c‐ANCA), perinuclear ANCA (p‐ANCA), antiphospholipid antibodies (aPLs), and anticyclic citrullinated peptide (anti‐CCP) occurrence was evaluated using a solid‐phase enzyme‐linked immunosorbent assay (ELISA). Results: The results showed that the occurrence of ANAs, anti‐dsDNA, anti‐CCP, c‐ANCA, and p‐ANCA was significantly higher in the COVID‐19 patients compared to serum obtained from healthy subjects (p <.0001, p <.0001, p <.0001, p <.05, and p <.001, respectively). The positive number of anti‐CCP tests increased significantly in severe COVID‐19 compared to the moderate group (p <.01). Conclusion: Our study further supports the development of autoantibodies related to systemic autoimmune rheumatologic diseases. To the best of our knowledge, this is the first study with a large sample size that reported the occurrence of anti‐CCP in a severe form of COVID‐19. [ABSTRACT FROM AUTHOR]

Desmoglein‐2 (DSG2) is a transmembrane glycoprotein belonging to the desmosomal cadherin family, which mediates cell–cell junctions; regulates cell proliferation, migration, and invasion; and promotes tumor development and metastasis. We previously showed serum DSG2 to be a potential biomarker for the diagnosis of esophageal squamous cell carcinoma (ESCC), although the significance and underlying molecular mechanisms were not identified. Here, we found that DSG2 was increased in ESCC tissues compared with adjacent tissues. In addition, we demonstrated that DSG2 promoted ESCC cell migration and invasion. Furthermore, using interactome analysis, we identified serine/threonine‐protein kinase D2 (PRKD2) as a novel DSG2 kinase that mediates the phosphorylation of DSG2 at threonine 730 (T730). Functionally, DSG2 promoted ESCC cell migration and invasion dependent on DSG2‐T730 phosphorylation. Mechanistically, DSG2 T730 phosphorylation activated EGFR, Src, AKT, and ERK signaling pathways. In addition, DSG2 and PRKD2 were positively correlated with each other, and the overall survival time of ESCC patients with high DSG2 and PRKD2 was shorter than that of patients with low DSG2 and PRKD2 levels. In summary, PRKD2 is a novel DSG2 kinase, and PRKD2‐mediated DSG2 T730 phosphorylation promotes ESCC progression. These findings may facilitate the development of future therapeutic agents that target DSG2 and DSG2 phosphorylation. © 2024 The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Background: Aberrant expressions of desmoglein 2 (Dsg2) and desmocollin 2(Dsc2), the two most widely distributed desmosomal cadherins, have been found to play various roles in cancer in a context-dependent manner. Their specific roles on breast cancer (BC) and the potential mechanisms remain unclear. Methods: The expressions of Dsg2 and Dsc2 in human BC tissues and cell lines were assessed by using bioinformatics analysis, immunohistochemistry and western blotting assays. Wound-healing and Transwell assays were performed to evaluate the cells' migration and invasion abilities. Plate colony-forming and MTT assays were used to examine the cells' capacity of proliferation. Mechanically, Dsg2 and Dsc2 knockdown-induced malignant behaviors were elucidated using western blotting assay as well as three inhibitors including MK2206 for AKT, PD98059 for ERK, and XAV-939 for β-catenin. Results: We found reduced expressions of Dsg2 and Dsc2 in human BC tissues and cell lines compared to normal counterparts. Furthermore, shRNA-mediated downregulation of Dsg2 and Dsc2 could significantly enhance cell proliferation, migration and invasion in triple-negative MDA-MB-231 and luminal MCF-7 BC cells. Mechanistically, EGFR activity was decreased but downstream AKT and ERK pathways were both activated maybe through other activated protein tyrosine kinases in shDsg2 and shDsc2 MDA-MB-231 cells since protein tyrosine kinases are key drivers of triple-negative BC survival. Additionally, AKT inhibitor treatment displayed much stronger capacity to abolish shDsg2 and shDsc2 induced progression compared to ERK inhibition, which was due to feedback activation of AKT pathway induced by ERK inhibition. In contrast, all of EGFR, AKT and ERK activities were attenuated, whereas β-catenin was accumulated in shDsg2 and shDsc2 MCF-7 cells. These results indicate that EGFR-targeted therapy is not a good choice for BC patients with low Dsg2 or Dsc2 expression. Comparatively, AKT inhibitors may be more helpful to triple-negative BC patients with low Dsg2 or Dsc2 expression, while therapies targeting β-catenin can be considered for luminal BC patients with low Dsg2 or Dsc2 expression. Conclusion: Our finding demonstrate that single knockdown of Dsg2 or Dsc2 could promote proliferation, motility and invasion in triple-negative MDA-MB-231 and luminal MCF-7 cells. Nevertheless, the underlying mechanisms were cellular context-specific and distinct. [ABSTRACT FROM AUTHOR]

Autoimmune autonomic ganglionopathy (AAG) is a disease of autonomic failure caused by ganglionic acetylcholine receptor (gAChR) autoantibodies. Although the detection of autoantibodies is important for distinguishing the disease from other neuropathies that present with autonomic dysfunction, other factors are important for accurate diagnosis. Here, we provide a comprehensive review of the clinical features of AAG, highlighting differences in clinical course, clinical presentation, and laboratory findings from other neuropathies presenting with autonomic symptoms. The first step in diagnosing AAG is careful history taking, which should reveal whether the mode of onset is acute or chronic, followed by an examination of the time course of disease progression, including the presentation of autonomic and extra-autonomic symptoms. AAG is a neuropathy that should be differentiated from other neuropathies when the patient presents with autonomic dysfunction. Immune-mediated neuropathies, such as acute autonomic sensory neuropathy, are sometimes difficult to differentiate, and therefore, differences in clinical and laboratory findings should be well understood. Other non-neuropathic conditions, such as postural orthostatic tachycardia syndrome, chronic fatigue syndrome, and long COVID, also present with symptoms similar to those of AAG. Although often challenging, efforts should be made to differentiate among the disease candidates. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD) is a severe retinal disease that causes irreversible visual loss and blindness in elderly populations worldwide. The pathological mechanism of AMD is complex, involving the interactions of multiple environmental and genetic factors. A poor understanding of the disease leads to limited treatment options and few effective prevention methods. The discovery of autoantibodies in AMD patients provides an opportunity to explore the pathogenesis and treatment direction of the disease. This review focuses on the mitochondria-associated autoantibodies and summarizes the functional roles of mitochondria under physiological conditions and their alterations during the pathological states. Additionally, it discusses the crosstalk between mitochondria and other organelles, as well as the mitochondria-related therapeutic strategies in AMD. [ABSTRACT FROM AUTHOR]

Background: Anti‐α6β4 integrin autoantibodies can be observed in some patients with mucous membrane pemphigoid. We have previously identified anti‐α6β4 integrin extracellular domain autoantibodies together with anti‐BP180 NC16A antibodies in a patient with DPP‐4 inhibitor‐induced bullous pemphigoid. However, the significance and impact of anti‐α6β4 integrin antibodies are unknown. Objectives: To characterize anti‐α6β4 integrin extracellular domain autoantibodies in pemphigoid patients, to determine whether these antibodies inhibit laminin‐α6β4 integrin binding and to observe their systemic effects. Methods: Anti‐α6β4 integrin autoantibodies were analysed by staining cells expressing the extracellular region of α6β4 integrin with sera from 20 patients with pemphigoid. The anti‐α6β4 integrin autoantibodies were characterized using different transfectants. The binding of laminins to α6β4 integrin was studied using cells expressing the activated conformation of α6β4 integrin and the inhibitory effect of the autoantibodies on the binding of laminins to α6β4 integrin was tested. Trends in antibody titres and clinical symptoms were quantified and analysed. Results: IgG autoantibodies against the extracellular domain of anti‐α6β4 integrin were found in some patients with pemphigoid. Laminin binding to α6β4 integrin was observed in the active conformation of α6β4 integrin, and serum from a patient with a high titre of anti‐α6β4 integrin antibodies inhibited the binding of both laminin‐511 and laminin‐332 to α6β4 integrin. α6β4 integrin is expressed on the basement membrane of both skin and small intestine, and exfoliation was observed in the patient's epidermis and small intestinal epithelium. A reduction in the titre of the anti‐α6β4 integrin antibody was associated with improvement in both skin and gastrointestinal symptoms. Conclusions: This study demonstrated the presence of anti‐α6β4 integrin extracellular domain‐specific autoantibodies in some patients with pemphigoid. In addition, these autoantibodies showed inhibitory activity on α6β4 integrin‐laminin binding. Anti‐α6β4 integrin antibodies can affect the gastrointestinal tract as well as the skin and oral mucosa. [ABSTRACT FROM AUTHOR]

Desmoglein-2 (DSG2) is a calcium-binding single pass transmembrane glycoprotein and a member of the large cadherin family. Until recently, DSG2 was thought to only function as a cell adhesion protein embedded within desmosome junctions designed to enable cells to better tolerate mechanical stress. However, additional roles for DSG2 outside of desmosomes are continuing to emerge, particularly in cancer. Herein, we review the current literature on DSG2 in cancer and detail its impact on biological functions such as cell adhesion, proliferation, migration, invasion, intracellular signaling, extracellular vesicle release and vasculogenic mimicry. An increased understanding of the diverse repertoire of the biological functions of DSG2 holds promise to exploit this cell surface protein as a potential prognostic biomarker and/or target for better patient outcomes. This review explores the canonical and non-canonical functions of DSG2, as well as the context-dependent impacts of DSG2 in the realm of cancer. [ABSTRACT FROM AUTHOR]

Background: An accurate and easily accessible method for diagnosing malignancies in local veterinary clinics has not yet been established. Objectives: To investigate the usefulness of serum thymidine kinase 1 (TK1) protein and its autoantibody as tumor biomarkers in dogs. Animals: Serum samples from 1702 dogs were collected from local animal hospitals and referral animal medical centers in South Korea. Methods: TK1 protein OD value and TK1 autoantibody ratio (TK1 autoantibody OD/total IgG OD) in serum samples of dogs classified into healthy controls, group with nontumor disease, group with benign and group with malignant tumors were measured using lateral flow immunochromatographic assay methods. Results: TK1 autoantibody levels were significantly higher in malignant tumor group (median 0.71) than in healthy controls (median 0.34), group with nontumor disease (median 0.34), and group with benign tumor (median 0.32, Welch t test, P <.0001). They were also significantly different among dogs with carcinomas (median 0.77), hematopoietic tumors (median 0.71), and sarcomas (median 0.56) than in healthy controls (median 0.34, post hoc Games‐Howell test, P <.0001). In the receiver operating characteristic curve of TK1 protein, AUC was 0.633 (95% CI: 0.592‐0.675, P <.0001). The AUC of TK1 autoantibody ratio was 0.758 (95% CI: 0.723‐0.793, P <.0001). Conclusions and Clinical Importance: TK1 autoantibody is a potentially useful biomarker for differentiating between healthy and tumor‐bearing dogs, better than TK1 protein measurement. However, both were inadequate when used as single biomarkers for screening dogs to discover occult malignant tumors. [ABSTRACT FROM AUTHOR]

• Point-mutated variants of β2GPI identified the pathogenic domain I epitope. • However, point mutations could affect the structure of β2GPI. • We show the interaction of β2GPI with anti-domain I antibodies by SAXS. • The antibodies represent the majority of pathogenic auto-antibodies present in APS. [ABSTRACT FROM AUTHOR]

This document is a letter published in the journal Neurological Sciences. The authors conducted a study using Mendelian randomization analysis to explore the causal relationship between 25-hydroxyvitamin D (25(OH)D) levels and the risk of developing neuromyelitis optica spectrum disorder (NMOSD). They used genome-wide association study (GWAS) data on NMOSD and 25(OH)D levels to analyze the genetic variations and their effects on the disease. The results showed no strong evidence of a causal association between 25(OH)D levels and NMOSD risk in a population of European ancestry. However, a causal relationship was observed between genetically predicted 25(OH)D levels and AQP4-ab-positive NMOSD risk. The study suggests that low vitamin D levels may be a risk factor for AQP4-ab-positive NMOSD and highlights the importance of further research in this area. [Extracted from the article]

Background: Pemphigus is a chronic potentially fatal autoimmune bullous disorder. Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are the two common subtypes. PV is the most common and aggressive type characterized by oral mucosal erosions and cutaneous lesions. PF presents with blisters on the scalp, face, and upper trunk, and spares the mucosae. Direct immunofluorescence (DIF) is the gold standard for diagnosis. Immunohistochemistry (IHC) is an emerging alternate diagnostic tool. In this study, our objectives were to identify the staining patterns of desmoglein 1 (dsg 1) and desmoglein 3 (dsg 3) IHC and to correlate the same with autoantibody levels and clinical severity in patients with PV and PF. Methods: Forty‐nine clinically, histologically, and DIF‐confirmed cases of pemphigus were included in the study. The IHC patterns were scored from 0 to 3+ with 3+ dsg 1 IHC exhibiting intense membranous staining in the upper layers of the epidermis and 3+ dsg 3 IHC showing intense basal layer staining. Enzyme‐linked immunosorbent assay (ELISA) for anti‐dsg 1 and 3 antibodies was performed in 38 cases where serum samples were available. The pemphigus disease activity index system was utilized for clinical scoring. Results: A 0 to 1+ score was observed for dsg 1 IHC in 100% of PF cases. A score of 0 to 1+ was observed for dsg 3 IHC in 97.3% of PV cases. One hundred percent of cases with PF and 83.9% of patients with PV tested positive for ELISA anti‐dsg 1 and 3 antibody titers, respectively. Anti‐dsg 1 and 3 ELISA titers significantly correlated with the dsg 1 and dsg 3 IHC scores. The mucosal scores showed a significant association with both dsg 1 and 3 IHC (p < 0.001). The cutaneous scores showed a significant association with the dsg 3 IHC (p < 0.001). Conclusion: The IHC patterns for dsg 1 and 3 proved reliable in giving concordant results with the ELISA antibody titers and clinical severity. [ABSTRACT FROM AUTHOR]

Organ culture storage techniques for corneoscleral limbal (CSL) tissue have improved the quality of corneas for transplantation and allow for longer storage times. Cultured limbal tissue has been used for stem cell transplantation to treat limbal stem cell deficiency (LSCD) as well as for research purposes to assess homeostasis mechanisms in the limbal stem cell niche. However, the effects of organ culture storage conditions on the quality of limbal niche components are less well described. Therefore, in this study, the morphological and immunohistochemical characteristics of organ-cultured limbal tissue are investigated and compared to fresh limbal tissues by means of light and electron microscopy. Organ-cultured limbal tissues showed signs of deterioration, such as edema, less pronounced basement membranes, and loss of the most superficial layers of the epithelium. In comparison to the fresh limbal epithelium, organ-cultured limbal epithelium showed signs of ongoing proliferative activity (more Ki-67+ cells) and exhibited an altered limbal epithelial phenotype with a loss of N-cadherin and desmoglein expression as well as a lack of precise staining patterns for cytokeratin ((CK)14, CK17/19, CK15). The analyzed extracellular matrix composition was mainly intact (collagen IV, fibronectin, laminin chains) except for Tenascin-C, whose expression was increased in organ-cultured limbal tissue. Nonetheless, the expression patterns of cell–matrix adhesion proteins varied in organ-cultured limbal tissue compared to fresh limbal tissue. A decrease in the number of melanocytes (Melan-A+ cells) and Langerhans cells (HLA-DR+, CD1a+, CD18+) was observed in the organ-cultured limbal tissue. The organ culture-induced alterations of the limbal epithelial stem cell niche might hamper its use in the treatment of LSCD as well as in research studies. In contrast, reduced numbers of donor-derived Langerhans cells seem associated with better clinical outcomes. However, there is a need to consider the preferential use of fresh CSL for limbal transplants and to look at ways of improving the limbal stem cell properties of stored CSL tissue. [ABSTRACT FROM AUTHOR]

Introduction: A recently discovered facet of paraneoplastic adrenocorticotropic hormone (ACTH) deficiency exists in two forms: a paraneoplastic spontaneous isolated ACTH deficiency (IAD) and an immune checkpoint inhibitor (ICI)-related hypophysitis. Autoantibodies against corticotrophs, such as circulating antiproopiomelanocortin (POMC) antibodies are considered disease markers. However, the number of identified cases was limited, implying that the characteristics of these autoantibodies are not fully understood. Methods: We investigate circulating autoimmune autoantibodies in detail through a novel case of IAD that developed as a paraneoplastic autoimmune ACTH deficiency.Results: The patient developed IAD after 25 weeks of ICI therapy for metastasis of large-cell neuroendocrine carcinoma at 69 years of age. Ectopic ACTH expression and infiltration of CD3+, CD4+, CD8+, and CD20+ lymphocytes were observed in the tumor tissues and circulating anti-POMC antibodies were detected specifically in the patient’s serum. Moreover, detailed analyses of immunofluorescence staining using patient serum revealed that the recognition site of the autoantibody was ACTH25-39, which had not been identified in previous cases of paraneoplastic autoimmune ACTH deficiency.Conclusion: This case involved a combination of paraneoplastic spontaneously acquired IAD and ICI-related hypophysitis occupying the middle ground. Moreover, our study reveals new aspects of anti-POMC antibodies in patients with paraneoplastic ACTH deficiency. This report expands our understanding of the immunological landscape and provides new insights for the identification of antibodies associated with paraneoplastic autoimmune ACTH deficiency. [ABSTRACT FROM AUTHOR]

Background: Glucocorticoids are the first-line treatment for Pemphigus vulgaris (PV), but its serious side effects can be life-threatening for PV patients. Tacrolimus (FK506) has been reported to have an adjuvant treatment effect against PV. However, the mechanism underlying the inhibitory effect of FK506 on PV-IgG-induced acantholysis is unclear. Objective: The objective of this study was to explore the effect of FK506 on desmoglein (Dsg) expression and cell adhesion in an immortalized human keratinocyte cell line (HaCaT cells) stimulated with PV sera. Methods: A cell culture model of PV was established by stimulating HaCaT cells with 5% PV sera with or without FK506 and clobetasol propionate (CP) treatment. The effects of PV sera on intercellular junctions and protein levels of p38 mitogen-activated protein kinase (p38MAPK), heat shock protein 27 (HSP27), and Dsg were assayed using western blot analysis, immunofluorescence staining, and a keratinocyte dissociation assay. Results: PV sera-induced downregulation of Dsg3 was observed in HaCaT cells and was blocked by FK506 and/or CP. Immunofluorescence staining revealed that linear deposits of Dsg3 on the surface of HaCaT cells in the PV sera group disappeared and were replaced by granular and agglomerated fluorescent particles on the cell surface; however, this effect was reversed by FK506 and/or CP treatment. Furthermore, cell dissociation assays showed that FK506 alone or in combination with CP increased cell adhesion in HaCaT cells and ameliorated loss of cell adhesion induced by PV sera. Additionally, FK506 noticeably decreased the PV serum-induced phosphorylation of HSP 27, but had no effect on p38MAPK phosphorylation. Conclusion: FK506 reverses PV-IgG induced-Dsg depletion and desmosomal dissociation in HaCaT cells, and this effect may be obtained by inhibiting HSP27 phosphorylation. [ABSTRACT FROM AUTHOR]

Objective: Topoisomerase I (topo I) is a highly conserved enzyme which is known to reduce torsional stress at double-stranded (ds) DNA. Torsional stress induced by supercoiling of dsDNA requires either very long dsDNA existing in genomic DNA or circulation as presented in plasmid DNA. To enable DNA relaxation, topo I induce a transient single-strand break followed by stress-relieving rotation of the released DNA strand. Our group found by serendipity that the topo I inhibitor irinotecan is able to suppress murine systemic lupus erythematosus (SLE), an autoimmune disease which is characterized by the existence of pathogenic anti-dsDNA antibodies (abs). As a possible mechanism we demonstrated in the absence of immunosuppression an increased binding of anti-dsDNA abs to long genomic or circulated plasmid dsDNA modified with topo I. Results: Here we show that this effect requires active site tyrosine of topo I which is known to facilitate DNA relaxation activity. Moreover, topo I enhanced anti-dsDNA abs binding to short linear oligonucleotides down to a size of 42 bp. Since oligonucleotides of such length are devoid of torsional stress and relaxation respectively, our results suggest a new and unknown function for the enzyme topo I. [ABSTRACT FROM AUTHOR]

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are a family of membrane molecules that recognize sialic acid. Most of them are inhibitory receptors that inhibit immune-cell activation by recognizing sialic acid as a self-motif. Human B cells express CD22 (also known as Siglec-2), Siglec-5, Siglec-6 and Siglec-10 whereas mouse B cells express CD22 and Siglec-G (ortholog of human Siglec-10). Siglecs recognize both sialylated molecules expressed on the same cell (cis -ligands) and those expressed by other cells (trans -ligands). In Guillain–Barré syndrome (GBS), antibody production to gangliosides (which are sialic acid-containing glycolipids) expressed by neurons plays a pathogenic role. A Siglec-10 variant deficient in recognition of gangliosides is genetically associated with GBS, suggesting that Siglec-10 induces self-tolerance to gangliosides by recognizing gangliosides as trans -ligands. Recognition of the BCR as a cis -ligand by Siglec-G and CD22 suppresses BCR signaling in B-1 cells and conventional B cells, respectively. This signal suppression prevents excess expansion of B-1 cells and is involved in the quality control of signaling-competent B cells by setting a threshold for tonic signaling during B cell development. CD22 recognizes other cis -ligands including CD22 and β7 integrin. Interaction of CD22 with other CD22 molecules induces CD22 clustering that suppresses CD22-mediated signal inhibition upon BCR ligation, and interaction with β7 integrin maintains its function in the gut-homing of B cells. Taken together, interactions of B cell Siglecs with multiple trans - and cis -ligands play important roles in B cell homeostasis and immune responses. [ABSTRACT FROM AUTHOR]

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AimsArrhythmogenic cardiomyopathy (ACM) is characterized by progressive loss of cardiomyocytes, and fibrofatty tissue replacement. Extracellular vesicles (EVs) secreted by cardiosphere-derived cells, immortalized, and engineered to express high levels of β-catenin, exert anti-inflammatory, and anti-fibrotic effects. The aim of the current study was to assess efficacy of EVs in an ACM murine model.Methods and resultsFour-week-old homozygous knock-in mutant desmoglein-2 (Dsg2mt/mt) were randomized to receive weekly EVs or vehicle for 4 weeks. After 4 weeks, DSG2mt/mt mice receiving EVs showed improved biventricular function (left, P < 0.0001; right, P = 0.0037) and less left ventricular dilation (P < 0.0179). Electrocardiography revealed abbreviated QRS duration (P = 0.0003) and QTc interval (P = 0.0006) in EV-treated DSG2mt/mt mice. Further electrophysiology testing in the EV group showed decreased burden (P = 0.0042) and inducibility of ventricular arrhythmias (P = 0.0037). Optical mapping demonstrated accelerated repolarization (P = 0.0290) and faster conduction (P = 0.0274) in Dsg2mt/mt mice receiving EVs. DSG2mt/mt hearts exhibited reduced fibrosis, less cell death, and preserved connexin 43 expression after EV treatment. Hearts of Dsg2mt/mt mice expressed markedly increased levels of inflammatory cytokines that were, in part, attenuated by EV therapy. The pan-inflammatory transcription factor nuclear factor-κB (NF-κB), the inflammasome sensor NLRP3, and the macrophage marker CD68 were all reduced in EV-treated animals. Blocking EV hsa-miR-4488 in vitro and in vivo reactivates NF-κB and blunts the beneficial effects of EVs.ConclusionsExtracellular vesicle treatment improved cardiac function, reduced cardiac inflammation, and suppressed arrhythmogenesis in ACM. Further studies are needed prior to translating the present findings to human forms of this heterogenous disease.

Aims/hypothesis: Appearance of multiple islet cell autoantibodies in early life is indicative of future progression to overt type 1 diabetes, however, at varying rates. Here, we aimed to study whether distinct metabolic patterns could be identified in rapid progressors (RP, disease manifestation within 18 months after the initial seroconversion to autoantibody positivity) vs. slow progressors (SP, disease manifestation at 60 months or later from the appearance of the first autoantibody). Methods: Longitudinal samples were collected from RP (n=25) and SP (n=41) groups at the ages of 3, 6, 12, 18, 24, or = 36 months. We performed a comprehensive metabolomics study, analyzing both polar metabolites and lipids. The sample series included a total of 239 samples for lipidomics and 213 for polar metabolites. Results: We observed that metabolites mediated by gut microbiome, such as those involved in tryptophan metabolism, were the main discriminators between RP and SP. The study identified specific circulating molecules and pathways, including amino acid (threonine), sugar derivatives (hexose), and quinic acid that may define rapid vs. slow progression to type 1 diabetes. However, the circulating lipidome did not appear to play a major role in differentiating between RP and SP. Conclusion/interpretation: Our study suggests that a distinct metabolic profile is linked with the type 1 diabetes progression. The identification of specific metabolites and pathways that differentiate RP from SP may have implications for early intervention strategies to delay the development of type 1 diabetes. [ABSTRACT FROM AUTHOR]

Heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT) are highly prothrombotic (thrombosis frequency ≥50%). Both are caused by platelet-activating anti-platelet factor 4 (PF4) antibodies, forming PF4/IgG-containing immune complexes that engage platelet FcγIIa receptors, producing strong platelet activation. In HIT, heparin crosslinks several PF4 molecules, whereas in VITT, anti-PF4 antibodies alone crosslink PF4. Sufficient levels of circulating anti-PF4 antibodies are needed to create the pathogenic immune complexes on platelet surfaces; this explains why certain serum (plasma)-based assays are highly sensitive for detecting HIT/VITT antibodies. Accordingly, HIT and VITT are "clinical-pathological" disorders, that is, positive testing for such antibodies—together with a compatible clinical picture—is integral for diagnosis. Heparin (low concentrations) enhances HIT antibody-induced platelet activation, but platelet activation by VITT sera is usually inhibited by heparin. For both HIT and VITT, high sensitivity (>99% and >95%, respectively) characterizes PF4-dependent enzyme immunoassays (EIAs) and PF4-enhanced platelet activation assays; in contrast, certain rapid immunoassays have high sensitivity for HIT (>90-97%) but poor sensitivity (<25%) for VITT. HIT and VITT antibodies are directed at distinct sites on PF4: solid-phase EIAs and platelet activation assays are indifferent to these distinct antigen targets, but rapid immunoassays are not. We discuss a conceptual model where PF4 is viewed as a "globe," with the heparin-binding site the "equator"; in this model, HIT antibodies are primarily directed at antigen site(s) at the north and south "poles" of PF4 (formed when PF4 binds to heparin), whereas VITT antibodies recognize sites on the equator. [ABSTRACT FROM AUTHOR]

Type 1 diabetes (T1D) is a chronic autoimmune disease that attacks the insulin-producing b cells of the pancreatic islets. Autoantibodies to b cell proteins typically appear in the circulation years before disease onset, and serve as the most accurate biomarkers of T1D risk. Our laboratory has recently discovered novel b cell proteins comprising hybrid proinsulin:islet amyloid polypeptide peptides (IAPP). T cells from a diabetic mouse model and T1D patients are activated by these hybrid peptides. In this study, we asked whether these hybrid molecules could serve as antigens for autoantibodies in T1D and prediabetic patients. We analyzed sera from T1D patients, prediabetics and healthy age-matched donors. Using a highly sensitive electrochemiluminescence assay, sera were screened for binding to recombinant proinsulin:IAPP probes or truncated derivatives. Our results show that sera from T1D patients contain antibodies that bind larger hybrid proinsulin:IAPP probes, but not proinsulin or insulin, at significantly increased frequencies compared to normal donors. Examination of sera from prediabetic patients confirms titers of antibodies to these hybrid probes in more than 80% of individuals, often before seroconversion. These results suggest that hybrid insulin peptides are common autoantigens in T1D and prediabetic patients, and that antibodies to these peptides may serve as valuable early biomarkers of the disease. [ABSTRACT FROM AUTHOR]

Background: Pemphigus vulgaris (PV) is a potentially fatal autoimmune bullous disease primarily caused by acantholysis of keratinocytes attributed to pathogenic desmoglein‐3 (Dsg3) autoantibodies. Interleukin‐37 (IL‐37) reportedly plays important roles in a variety of autoimmune diseases, but its role in PV is not clear. Objectives: To investigate whether IL‐37 plays a role in the occurrence and progression of PV. Methods: HaCaT keratinocytes were stimulated with anti‐Dsg3 antibody to establish an in vitro PV model, which was defined as anti‐Dsg3 group. Cells incubated with medium without anti‐Dsg3 treatment were used as control. IL‐37 was cultured with these cells infected with or without lentiviral vector shRNA‐Caveolin‐1 (sh‐Cav‐1‐LV). Cell dissociation assay and immunocytofluorescence were performed to assess keratinocyte dissociation, keratin retraction and Dsg3 endocytosis. Real‐time PCR was used to detect the mRNA level of Cav‐1, and western blot was used to determine the protein expression of Cav‐1, Dsg3, STAT3 and phosphorylated‐STAT3 (p‐STAT3). Results: The anti‐Dsg3 group showed more cell debris, increased keratin retraction, increased Dsg3 endocytosis, reduced Cav‐1 expression and co‐localization than the control group, while IL‐37 treatment neutralized all of these changes. Interestingly, Cav‐1 knockdown supressed the inhibitory effect of IL‐37 on keratinocyte dissociation and Dsg3 internalization. The protein expression of p‐STAT3 was increased in keratinocytes of the PV model but decreased by IL‐37. Re‐activation of the STAT3 pathway by colivelin supressed the inhibitory effect of IL‐37 on keratinocyte dissociation and Dsg3 internalization, along with upregulation of Cav‐1 and Dsg3. Conclusions: IL‐37 inhibited keratinocyte dissociation and Dsg3 endocytosis in an in vitro PV model through the upregulating Cav‐1 and inhibiting STAT3 pathway. [ABSTRACT FROM AUTHOR]

Pemphigus foliaceus is a superficial blistering disorder characterized by erosions and scaling in a seborrheic distribution. The condition typically occurs in healthy individuals but issues arise from delayed diagnosis. Many cases remain undiagnosed or misdiagnosed due to the lack of awareness of the condition. With use of common diagnostic tools, pemphigus foliaceus can be easily identified and monitored. Histological analysis exhibits "chicken wire" patterning along keratinocytes in the upper epidermis, whereas immunofluorescence study displays subcorneal acantholysis. Pemphigus foliaceus is confirmed via ELISA studies revealing the presence of autoantibodies against desmoglein 1. Once correctly diagnosed, typically the condition is responsive to corticosteroid therapy. However in recalcitrant cases such as in ours, adjunctive immunosuppressive therapy with dapsone or rituximab may be indicated. [ABSTRACT FROM AUTHOR]

BACKGROUND: Milk contains a massive class of minor proteins that are known for their various biological and molecular functions. Many whey proteins transfer the host defense mechanism to the human body. In this assay, electrophoresis followed by a high‐resolution mass spectrometry‐based proteomic approach has been applied to identify the whey proteome of Indian Jersey crossbreed bovines. RESULTS: Two search engines, MS Amanda and Sequest HT, have shown more than 29 minor proteins. Chromosomal mapping revealed that chromosomes 5 and 9 are expressing maximum proteins in the whey proteome. The principal component analysis, outlier plots, scree plots, score plots, and loading plots were generated to further assess the results. CONCLUSION: The majorly expressed ones are glycosylation‐dependent cell adhesion molecule‐1, ubiquitin, desmoglein, annexin, glycoprotein, arginase, histones, peroxiredoxin, vimentin, desmin, catenin, peripherin, and 70 kDa heat shock protein. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Regulation of cadherin‐mediated cell adhesion is crucial not only for maintaining tissue integrity and barrier function in the endothelium and epithelium but also for electromechanical coupling within the myocardium. Therefore, loss of cadherin‐mediated adhesion causes various disorders, including vascular inflammation and desmosome‐related diseases such as the autoimmune blistering skin dermatosis pemphigus and arrhythmogenic cardiomyopathy. Mechanisms regulating cadherin‐mediated binding contribute to the pathogenesis of diseases and may also be used as therapeutic targets. Over the last 30 years, cyclic adenosine 3′,5′‐monophosphate (cAMP) has emerged as one of the master regulators of cell adhesion in endothelium and, more recently, also in epithelial cells as well as in cardiomyocytes. A broad spectrum of experimental models from vascular physiology and cell biology applied by different generations of researchers provided evidence that not only cadherins of endothelial adherens junctions (AJ) but also desmosomal contacts in keratinocytes and the cardiomyocyte intercalated discs are central targets in this scenario. The molecular mechanisms involve protein kinase A‐ and exchange protein directly activated by cAMP‐mediated regulation of Rho family GTPases and S665 phosphorylation of the AJ and desmosome adaptor protein plakoglobin. In line with this, phosphodiesterase 4 inhibitors such as apremilast have been proposed as a therapeutic strategy to stabilize cadherin‐mediated adhesion in pemphigus and may also be effective to treat other disorders where cadherin‐mediated binding is compromised. [ABSTRACT FROM AUTHOR]

Pemphigus is a severe autoimmune bullous disease of the skin and/or mucous membranes caused by autoantibodies that mainly target the adhesion proteins desmoglein (Dsg) 3 and/or Dsg1. Clinically, pemphigus is characterized by flaccid blistering, leading to severe water and electrolyte loss. Before the introduction of corticosteroid treatment, the disease turned out to be fatal in many cases. Despite recent therapeutic improvements, treatment of pemphigus patients is centred on prolonged systemic immunosuppression and remains challenging. Current drug development for pemphigus has a strong focus on disease-causing B cells and autoantibodies and, more recently, also on modulating autoantibody-induced tissue pathology and keratinocyte signalling. This drug development requires reliable pre-clinical model systems replicating the pathogenesis of the human disease. Among those are neonatal and adult mouse models based on the transfer of Dsg3, Dsg1/3 or Dsg1-specific autoantibodies. To reduce the number of animal experiments, we recently established a standardized human skin organ culture (HSOC) model for pemphigus. This model reproduces the clinical phenotype of autoantibody-induced tissue pathology in pemphigus vulgaris. For induction of blistering, a recombinant single-chain variable fragment (scFv) targeting both Dsg1 and 3 is injected into pieces of human skin (obtained from plastic surgeries). Further characterization of the HSOC model demonstrated that key morphologic, molecular and immunologic features of pemphigus are being replicated. Thus, the pemphigus HSOC model is an excellent alternative to pemphigus animal model systems that are based on the transfer of (auto)antibodies. [ABSTRACT FROM AUTHOR]

Pemphigus vulgaris (PV) is an acquired autoimmune blistering disease characterized by the production of autoantibodies targeting desmosomal cadherins, primarily desmoglein 1 and desmoglein 3, leading to acantholysis. The etiology of PV is multifactorial, including genetic susceptibility. This retrospective study aimed to evaluate the association of HLA class II alleles and PV and to examine the impact of PV-associated HLA class II alleles on the concentration of anti-desmoglein antibodies. The study group included 30 patients in whom the diagnosis of PV was confirmed by histopathological analysis, immunofluorescence findings, and ELISA testing for detecting antibodies against desmoglein 1 and desmoglein 3. HLA class II alleles were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP). The control group consisted of 190 healthy volunteer blood donors. Data analysis revealed a significantly higher frequency of HLA class II alleles in our population of patients with PV, including HLA-DRB1*04:02, HLA-DRB1*14:54, HLA-DQB1*03:02, HLA-DQB1*05:03, HLA-DQA1*03:01, and HLADQA1* 01:04, as well as a significantly lower frequency of HLA-DQA1*05:01 compared to the control group. We have also investigated the influence of risk alleles for PV, recognized in almost all study populations, HLA-DRB1*04:02 and HLA-DQB1*05:03, on the concentration of antibodies against desmogleins 1 and 3 in relation to the presence of these alleles. The results showed significantly higher levels of antibodies directed against desmoglein 3 among patients with DRB1*04:02 compared to patients without this allele. No difference was found for anti-desmoglein 1 antibodies. Regarding DQB1*05:03 allele, statistical analysis showed no differences in the concentration of anti-desmoglein antibodies in patients carrying this allele versus those without it. [ABSTRACT FROM AUTHOR]

Pemphigus is a life-threatening, chronic, autoimmune bullous disease affecting both the skin and the mucous membranes. Based on the mainstream concept that blister formation occurs upon binding of autoantibodies to their antigen proteins (desmoglein1, DSG1 and desmoglein3, DSG3), current therapies mostly aim to suppress the immune system. To avoid the severe side effects associated with the chronic use of immunosuppressive treatments, we have developed PC111, a fully human monoclonal antibody targeting human Fas ligand (FasL). We have provided a number of in vitro and in vivo evidences showing that soluble FasL induces keratinocyte apoptosis followed by acantholysis. An anti-murine FasL prevents blister formation in the pemphigus neonatal mouse model. To confirm the mechanism of action (MoA) and the efficacy of PC111 in a human pemphigus context, we used the keratinocyte dissociation assay and two independent Human Skin Organ Cultures (HSOC) pemphigus models. PC111 reduced acantholysis in vitro, as shown by the dose-dependent reduction of fragments in the monolayer cultures. In the first HSOC model, normal human skin was subcutaneously injected with a scFv antibody fragment directed against DSG1 and DSG3, resulting in a severe acantholysis (70-100%) after 24 hours. PC111 inhibited blister formation to around 50% of control. In the second model, normal human skin was injected with a mixture of pemphigus patients' autoantibodies resulting in a less severe acantholysis (20-30%). PC111 significantly suppressed blister formation to more than 75% up to 72 hours. These results confirm PC111 MoA and demonstrates the efficacy of the anti-FasL antibody also in a pemphigus setting. [ABSTRACT FROM AUTHOR]

Autoimmune bullous disease (AIBD) is a severe skin disorder caused by autoantibodies that target intercellular or cell-matrix adhesion proteins. Currently, the preferred treatment for AIBD involves the use of glucocorticoids or traditional immunosuppressants. Additionally, the utilization of biological agents such as rituximab, omalizumab, and dupilumab is on the rise. However, effectively managing AIBD remains a challenge. The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway has been implicated in various inflammatory diseases. In recent years, a range of drugs known as JAK inhibitors, which target this pathway, have been developed. Several studies have explored the efficacy and safety of JAK inhibitors for treating AIBD. Consequently, this review begins by examining the role of the JAK/STAT pathway in AIBD, summarizing the application of different JAK inhibitors in AIBD treatment, and emphasizing the importance of disease management in treating AIBD with JAK inhibitors. Furthermore, it highlights the need for a better understanding of the JAK/STAT pathway's role in AIBD, as well as the effectiveness and safety of JAK inhibitors for treating this disease. [ABSTRACT FROM AUTHOR]

The pathogenesis of atopic dermatitis (AD) is multifactorial, including immune dysregulation and epidermal barrier defects, and a novel therapeutic modality that can simultaneously target multiple pathways is needed. We investigated the therapeutic effects of exosomes (IFN-γ-iExo) secreted from IFN-γ-primed induced pluripotent stem cell-derived mesenchymal stem cells (iMSC) in mice with Aspergillus fumigatus-induced AD. IFN-γ-iExo was epicutaneously administered to mice with AD-like skin lesions. The effects of IFN-γ-iExo treatment were investigated through clinical scores, transepidermal water loss (TEWL) measurements, and histopathology. To elucidate the therapeutic mechanism, we used an in vitro model of human keratinocyte HaCaT cells stimulated with IL-4 and IL-13 and performed extensive bioinformatics analysis of skin mRNA from mice. The expression of indoleamine 2,3-dioxygenase was higher in IFN-γ primed iMSCs than in iMSCs. In human keratinocyte HaCaT cells, treatment with IFN-γ-iExo led to decreases in the mRNA expression of thymic stromal lymphopoietin, IL-25, and IL-33 and increases in keratin 1, keratin 10, desmoglein 1, and ceramide synthase 3. IFN-γ-iExo treatment significantly improved clinical and histological outcomes in AD mice, including clinical scores, TEWL, inflammatory cell infiltration, and epidermal thickness. Bioinformatics analysis of skin mRNA from AD mice showed that IFN-γ-iExo treatment is predominantly involved in skin barrier function and T cell immune response. Treatment with IFN-γ-iExo improved the clinical and histological outcomes of AD mice, which were likely mediated by restoring proper skin barrier function and suppressing T cell-mediated immune response. [ABSTRACT FROM AUTHOR]

Bullous pemphigoid (BP) is an autoimmune blistering skin disease, of which the incidence has increased in recent years. BP is characterized by circulating IgG and IgE autoantibodies against the hemidesmosomal proteins BP180 and BP230. Although autoantibodies trigger inflammatory cascades that lead to blister formation, effector cells and cell-mediated autoimmunity must also be considered as important factors in the pathogenesis of BP. The aim of this review is to outline the current knowledge on the role of eosinophils, basophils, and neutrophils in BP. [ABSTRACT FROM AUTHOR]

Key Clinical Message: There may be a connection between pemphigus vulgaris and nephrotic syndrome, as evidenced by the occurrence of focal segmental glomerulosclerosis in our pemphigus vulgaris patient and reviewing relevant literature. Therefore, if a patient with pemphigus vulgaris presents with bilateral lower extremity edema or proteinuria detected during urinalysis, it could indicate involvement of the kidneys. Pemphigus vulgaris is a type of autoimmune blistering disease characterized by the presence of IgG autoantibodies against desmogleins 3 and 1. It is important to evaluate potential autoimmune associations in patients with pemphigus vulgaris so that appropriate laboratory and physical examinations can be performed to monitor for any increased risk of other autoimmune disorders. This case report describes a 55‐year‐old woman who presented with oral and axillary erosions, which were diagnosed as pemphigus vulgaris based on skin histopathology and immunofluorescence. During follow‐up, the patient was found to have proteinuria, which led to referral to a nephrologist. The patient was diagnosed with nephrotic syndrome and minimal change disease after a biopsy. Despite treatment, the patient's proteinuria persisted and serum creatinine levels increased, leading to a second biopsy which confirmed the diagnosis of focal segmental glomerulosclerosis. This study reports on the first case of pemphigus vulgaris with focal segmental glomerulosclerosis and reviews the literature on the co‐occurrence of acquired immunobullous diseases and nephrotic syndrome of any kind. [ABSTRACT FROM AUTHOR]

Pemphigus is an uncommon but life-threatening autoimmune blistering disease characterized by the presence of antibodies against desmogleins. Without effective treatment, pemphigus can result in significant morbidity and mortality. Existing consensus statements on pemphigus management from international medical groups provide varying guidelines, especially on treatment. Thus, on January 4, 2020, a panel of seven dermatology experts from the Taiwanese Dermatological Association (TDA) and one rheumatology expert convened to develop a consensus for the management of pemphigus. These experts with extensive experience in pemphigus management were recommended by their respective teaching hospitals and primary care clinics in Taiwan and by the TDA. The meeting reviewed the available consensus statements from international dermatology groups, including the European Dermatology Forum (EDF), the European Academy of Dermatology and Venereology (EADV), and the International Bullous Diseases Consensus Group. Using these guidelines as a basis for discussion and consensus formulation, these experts formulated their consensus statement that provides practical, concise but comprehensive recommendations as to the diagnosis, treatment, and monitoring of pemphigus patients in Taiwan. This consensus serves as a clinical reference for physicians for the management of pemphigus in Taiwan or wherever it may be applicable. [ABSTRACT FROM AUTHOR]

Introduction: IgG4 autoantibodies against paranodal proteins are known to induce acute-onset and often severe sensorimotor autoimmune neuropathies. How autoantibodies reach their antigens at the paranode in spite of the myelin barrier is still unclear. Methods: We performed in vitro incubation experiments with patient sera on unfixed and unpermeabilized nerve fibers and in vivo intraneural and intrathecal passive transfer of patient IgG to rats, to explore the access of IgG autoantibodies directed against neurofascin-155 and contactin-1 to the paranodes and their pathogenic effect. Results: We found that in vitro incubation resulted in weak paranodal binding of anti-contactin-1 autoantibodies whereas anti-neurofascin-155 autoantibodies bound to the nodes more than to the paranodes. After short-term intraneural injection, no nodal or paranodal binding was detectable when using antineurofascin- 155 antibodies. After repeated intrathecal injections, nodal more than paranodal binding could be detected in animals treated with antineurofascin- 155, accompanied by sensorimotor neuropathy. In contrast, no paranodal binding was visible in rats intrathecally injected with anti-contactin-1 antibodies, and animals remained unaffected. Conclusion: These data support the notion of different pathogenic mechanisms of anti-neurofascin-155 and anti-contactin-1 autoantibodies and different accessibility of paranodal and nodal structures. [ABSTRACT FROM AUTHOR]

Bullous pemphigoid (BP) is an autoimmune bullous disease, characterized by autoantibodies targeting BP180 and BP230. The role of interleukin (IL)‐36, a potent chemoattractant for granulocytes, in BP remains elusive.The expression of IL‐36 cytokines (IL‐36α, β, γ) and their antagonists (IL‐36Ra and IL‐38) was analysed in the skin and serum samples of patients with BP (n = 31), psoriasis (n = 10) and healthy controls (HC) (n = 14) by quantitative polymerase chain reaction and enzyme linked immunosorbent assay, respectively. Skin and serum levels of all cytokines were correlated with the Bullous Pemphigoid Disease Area Index (BPDAI) score and with the serum concentration of pathogenic antibodies.IL‐36α, IL‐36β, IL‐36γ and IL‐36Ra were significantly (p < 0.05) overexpressed in BP skin compared to HC, without remarkable differences relative to psoriasis skin. The expression of IL‐38 was significantly (p < 0.05) higher in BP compared to psoriasis skin.IL‐36α and γ, but not β, serum concentrations were significantly (p < 0.05) higher in BP compared to HC. IL‐36γ was significantly (p < 0.05) more expressed in the serum of psoriasis patients than BP. The serum concentration of IL‐36Ra and IL‐38 were similar between BP and HC, while IL‐38 serum levels were significantly (p < 0.05) higher in BP compared to psoriasis patients. Serum IL‐36α correlated significantly with BPDAI (r = 0.5 p = 0.001).IL‐36 agonists are increased in BP patients, both locally and systemically. Serum IL‐36α might represent a potential biomarker for BP. An inefficient balance between IL‐36 agonists and antagonists is likely to occur during BP inflammation. [ABSTRACT FROM AUTHOR]