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Human regulatory T cells (Tregs) suppress other T cells by converting the latent, inactive form of TGF-β1 into active TGF-β1. In Tregs, TGF-β1 activation requires GARP, a transmembrane protein that binds and presents latent TGF-β1 on the surface of Tregs stimulated through their T cell receptor. However, GARP is not sufficient because transduction of GARP in non-Treg T cells does not induce active TGF-β1 production. RGD-binding integrins were shown to activate TGF-β1 in several non-T cell types. Here we show that αVβ8 dimers are present on stimulated human Tregs but not in other T cells, and that antibodies against αV or β8 subunits block TGF-β1 activation in vitro. We also show that αV and β8 interact with GARP/latent TGF-β1 complexes in human Tregs. Finally, a blocking antibody against β8 inhibited immunosuppression by human Tregs in a model of xenogeneic graft-vs.-host disease induced by the transfer of human T cells in immunodeficient mice. These results show that TGF-β1 activation on the surface of human Tregs implies an interaction between the integrin αVβ8 and GARP/latent TGF-β1 complexes. Immunosuppression by human Tregs can be inhibited by antibodies against GARP or against the integrin β8 subunit. Such antibodies may prove beneficial against cancer or chronic infections.

Borderline personality disorder (BPD) is a severe mental health condition marked by impairments in self and interpersonal functioning. Stigma from health staff may often result in a reluctance to diagnose, impacting recovery trajectories. Qualitative interviews were conducted with participants (N = 15; M Age = 36.4 years, SD = 7.5; 93.3% female) with lived experience of BPD exploring topics of illness onset, insight, experience of diagnosis and treatment. Qualitative responses were analysed within a co‐design framework with a member of the research team who identifies as having a lived experience of BPD. On average, participant symptoms emerged at 12.1 years of age (SD = 6.6 years, range 1.5–27), but diagnoses of BPD were delayed until 30.2 years (SD = 7.8 years, range 18–44) resulting in a 'diagnosis gap' of 18.1 years (SD = 9.6 years, range 3–30). Participant explanations for BPD emergence varied from biological, psychological and social factors. Benefits of diagnosis (e.g., fostering insight, aiding treatment planning and reducing isolation) were contrasted with challenges (e.g., stigma and treatment unavailability). Delay in diagnosis was common, and no participants reported receiving a diagnosis of BPD during their adolescence yet 85% felt they would have benefited from a diagnosis in adolescence. Only a quarter (27%) felt highly supported in the diagnostic process. An ideal four‐step diagnosis procedure was outlined based on recommendations from participants with a lived experience; this involved the following: (1) explain the process, (2) assess thoroughly, (3) explore how the features are active in everyday life and (4) link diagnosis to evidence‐based treatment planning. [ABSTRACT FROM AUTHOR]

We previously demonstrated that tumor-infiltrating lymphocytes (TIL) in human breast cancer sometimes form organized tertiary lymphoid structures (TLS) characterized by CXCL13-producing T follicular helper (Tfh) cells. The present study found that [CD4.sup.+] Tfh TIL, [CD8.sup.+] TIL, and TIL-B, colocalizing in TLS, all express the CXCL13 receptor CXCR5. An ex vivo functional assay determined that only activated, functional Thl-oriented Tfh TIL ([PD-1.sup.hi][ICOS.sup.int] phenotype) provide help for immunoglobulin and IFN-[gamma] production. A functional Tfh TIL presence signals an active TLS, characterized by humoral (immunoglobulins, [Ki-67.sup.+] TIL-B in active germinal centers) and cytotoxic ([GZMB.sup.+][CD8.sup.+] and [GZMB.sup.+][CD68.sup.+] TIL plus Th1 gene expression) immune responses. Analysis of active versus inactive TLS in untreated patients revealed that the former are associated with positive clinical outcomes. TLS also contain functional T follicular regulatory (Tfr) TIL, which are characterized by a [CD25.sup.+][CXCR5.sup.+][GARP.sup.+][FOXP3.sup.+] phenotype and a demethylated FOXP3 gene. Functional Tfr inhibited functional Tfh activities via a glycoprotein A repetitions predominant (GARP)-associated TGF-[beta]-dependent mechanism. The activity of tumor-associated TLS was dictated by the relative balance between functional Tfh TIL and functional Tfr TIL. These data provide mechanistic insight into TLS processes orchestrated by functional Th1-oriented Tfh TIL, including TIL-B and [CD8.sup.+] TIL activation and immunological memory generation. Tfh TIL, regulated by functional Tfr TIL, are an expected key target of PD-1/PD-L1 blockade., Introduction Adaptive and innate antitumor immune responses and their exploitation in immunotherapy are recognized as key defenses in the fight against cancer. Across a diversity of tumor types, data support [...]

Simple Summary: Glycoprotein A repetitions predominant (GARP) is expressed at the surface of regulatory T lymphocytes (Tregs) in human and murine primary tumors and was shown to mediate TGF-β1 activation and immunosuppression by Tregs in tumor-bearing mice. The cellular sources and the implication of GARP in lymph nodes (LNs) during the metastatic cascade are still elusive. Here, we mined available scRNA-Seq datasets and conducted immunohistochemistry and in situ hybridization analyses of metastatic LNs from mice and patients with cervical or breast cancer. We found GARP expression not only in Tregs, but also in blood/lymphatic vessels, fibroblastic cells, and perivascular cells. Our study highlights for the first time GARP expression by specialized lymphatic endothelial cells in the subcapsular sinus, high endothelial venules (HEVs), and matrix-associated (fibroblastic/perivascular) cells. Several types of cancer spread through the lymphatic system via the sentinel lymph nodes (LNs). Such LN-draining primary tumors, modified by tumor factors, lead to the formation of a metastatic niche associated with an increased number of Foxp3+ regulatory T cells (Tregs). These cells are expected to contribute to the elaboration of an immune-suppressive environment. Activated Tregs express glycoprotein A repetitions predominant (GARP), which binds and presents latent transforming growth factor beta 1 (TGF-β1) at their surface. GARP is also expressed by other non-immune cell types poorly described in LNs. Here, we mapped GARP expression in non-immune cells in human and mouse metastatic LNs. The mining of available (human and murine) scRNA-Seq datasets revealed GARP expression by blood (BEC)/lymphatic (LEC) endothelial, fibroblastic, and perivascular cells. Consistently, through immunostaining and in situ RNA hybridization approaches, GARP was detected in and around blood and lymphatic vessels, in (αSMA+) fibroblasts, and in perivascular cells associated with an abundant matrix. Strikingly, GARP was detected in LECs forming the subcapsular sinus and high endothelial venules (HEVs), two vascular structures localized at the interface between LNs and the afferent lymphatic and blood vessels. Altogether, we here provide the first distribution maps for GARP in human and murine LNs. [ABSTRACT FROM AUTHOR]

Simple Summary: Incidence of thyroid cancer, including papillary thyroid cancer, is rapidly increasing. Oncogenes, such as the BRAFV600E, have been identified, and their effect on thyroid cancer cells have been studied in vitro and in mouse models. What is less understood is the impact of these mutations on thyroid cancer microenvironment and, in turn, the effect of changes in the microenvironment on tumor progression. We investigated the modifications in the cellular composition of thyroid cancer microenvironment using an inducible mouse model. We focused on a subpopulation of macrophages, expressing the STABILIN-1 protein, recruited in the thyroid tumor microenvironment following BRAFV600E expression. CRISPR/Cas9 genetic inactivation of Stablin-1 did not change macrophage recruitment but highlighted the immunosuppressive role of STABILIN-1-expressing macrophages. The identification of a similar subpopulation of STABILIN-1 macrophages in human thyroid diseases supports a conserved role for these macrophages and offers an opportunity for intervention. Papillary thyroid carcinoma (PTC) is the most frequent histological subtype of thyroid cancers (TC), and BRAFV600E genetic alteration is found in 60% of this endocrine cancer. This oncogene is associated with poor prognosis, resistance to radioiodine therapy, and tumor progression. Histological follow-up by anatomo-pathologists revealed that two-thirds of surgically-removed thyroids do not present malignant lesions. Thus, continued fundamental research into the molecular mechanisms of TC downstream of BRAFV600E remains central to better understanding the clinical behavior of these tumors. To study PTC, we used a mouse model in which expression of BRAFV600E was specifically switched on in thyrocytes by doxycycline administration. Upon daily intraperitoneal doxycycline injection, thyroid tissue rapidly acquired histological features mimicking human PTC. Transcriptomic analysis revealed major changes in immune signaling pathways upon BRAFV600E induction. Multiplex immunofluorescence confirmed the abundant recruitment of macrophages, among which a population of LYVE-1+/CD206+/STABILIN-1+ was dramatically increased. By genetically inactivating the gene coding for the scavenger receptor STABILIN-1, we showed an increase of CD8+ T cells in this in situ BRAFV600E-dependent TC. Lastly, we demonstrated the presence of CD206+/STABILIN-1+ macrophages in human thyroid pathologies. Altogether, we revealed the recruitment of immunosuppressive STABILIN-1 macrophages in a PTC mouse model and the interest to further study this macrophage subpopulation in human thyroid tissues. [ABSTRACT FROM AUTHOR]

IL-27, a novel heterodimeric cytokine produced by antigen-presenting cells, signals through the T cell cytokine receptor [(TCCR).sup./wsx-1] expressed on naive CD[4.sup.+] T cells and natural killer cells. TCC[R.sup./wsx-1] deficiency results in delayed T helper type 1 ([T.sub.H]1) development through an unresolved mechanism. We report here that IL-27 stimulation in developing murine T helper cells potently induces the expression of the major [T.sub.H]1-specific transcription factor T-bet and its downstream target IL-12R [beta]2, independently of IFN[gamma]. In addition, IL-27 suppresses basal expression of GATA-3, the critical [T.sub.H]2-specific transcription factor that inhibits [T.sub.H]1 development by down-regulating signal transducer and activator of transcription (Stat) 4. IL-27 signaling through TCC[R.sup./wsx-1] induces phosphorylation of Stat1, Stat3, Stat4, and Stat5. Stat1 is required for suppression of GATA-3, but T-bet induction by IL-27 can also be mediated through a Stat1-independent pathway. Despite its [T.sub.H]1-like signaling profile, IL-27 is not sufficient to drive the differentiation of CD[4.sub.+] T cells into IFN[gamma]-producing cells. Similarly, IL-27 induces T-bet expression in primary natural killer cells, but this does not result in an increase of IFN[gamma], production or cytotoxic activity. Therefore, although IL-27 is unable to drive IFN[gamma] production on its own, it plays an important role in the early steps of [T.sub.H]1 commitment by contributing in a paracrine manner to the control of IL-12 responsiveness.

When combined with anti-PD-1, monoclonal antibodies (mAbs) against GARP:TGF-β1 complexes induced more frequent immune-mediated rejections of CT26 and MC38 murine tumors than anti-PD-1 alone. In both types of tumors, the activity of anti-GARP:TGF-β1 mAbs resulted from blocking active TGF-β1 production and immunosuppression by GARP-expressing regulatory T cells. In CT26 tumors, combined GARP:TGF-β1/PD-1 blockade did not augment the infiltration of T cells, but did increase the effector functions of already present anti-tumor T cells. Here we show that, in contrast, in MC38, combined GARP:TGF-β1/PD-1 blockade increased infiltration of T cells, as a result of increased extravasation of T cells from blood vessels. Unexpectedly, combined GARP:TGF-β1/PD-1 blockade also increased the density of GARP+ blood vessels covered by pericytes in MC38, but not in CT26 tumors. This appears to occur because anti-GARP:TGF-β1, by blocking TGF-β1 signals, favors the proliferation of and expression of adhesion molecules such as E-selectin by blood endothelial cells. The resulting densification of intratumoral blood vasculature probably contributes to increased T cell infiltration and to the therapeutic efficacy of GARP:TGF-β1/PD-1 blockade in MC38. We conclude from these distinct observations in MC38 and CT26, that the combined blockades of GARP:TGF-β1 and PD-1 can exert anti-tumor activity via multiple mechanisms, including the densification and normalization of intratumoral blood vasculature, the increase of T cell infiltration into the tumor and the increase of the effector functions of intratumoral tumor-specific T cells. This may prove important for the selection of cancer patients who could benefit from combined GARP:TGF-β1/PD-1 blockade in the clinics. [ABSTRACT FROM AUTHOR]

The current SARS‐CoV‐2 pandemic is wreaking havoc throughout the world and has rapidly become a global health emergency. A central question concerning COVID‐19 is why some individuals become sick and others not. Many have pointed already at variation in risk factors between individuals. However, the variable outcome of SARS‐CoV‐2 infections may, at least in part, be due also to differences between the viral subspecies with which individuals are infected. A more pertinent question is how we are to overcome the current pandemic. A vaccine against SARS‐CoV‐2 would offer significant relief, although vaccine developers have warned that design, testing and production of vaccines may take a year if not longer. Vaccines are based on a handful of different designs (i), but the earliest vaccines were based on the live, attenuated virus. As has been the case for other viruses during earlier pandemics, SARS‐CoV‐2 will mutate and may naturally attenuate over time (ii). What makes the current pandemic unique is that, thanks to state‐of‐the‐art nucleic acid sequencing technologies, we can follow in detail how SARS‐CoV‐2 evolves while it spreads. We argue that knowledge of naturally emerging attenuated SARS‐CoV‐2 variants across the globe should be of key interest in our fight against the pandemic. [ABSTRACT FROM AUTHOR]

While patient selection and clinical management have reduced high-dose IL-2 (HDIL2) immunotherapy toxicities, the immune mechanisms that underlie HDIL2-induced morbidity remain unclear. Here we show that dose-dependent morbidity and mortality of IL-2 immunotherapy can be modeled in human immune system (HIS) mice. Depletion of human T cell subsets during the HDIL2 treatment reduces toxicity, pointing to the central function of T cells. Preferential expansion of effector T cells secondary to defective suppressive capacity of regulatory T (Treg) cells after HDIL2 therapy further underscores the importance of Treg in the maintenance of immune tolerance. IL-2 toxicity is induced by selective depletion or inhibition of Treg after LDIL2 therapy, and is ameliorated in HDIL2-treated HIS mice receiving the PIM-1 kinase inhibitor, Kaempferol. Modeling IL-2 pathophysiology in HIS mice offers a means to understand the functions of effector and regulatory T cells in immune-mediated toxicities associated with cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Chlorella sp. is a green microalgae containing nutrients, vitamins, minerals, and chlorophyll. In some communities, Chlorella sp. is a traditional medicinal plant used for the management of inflammation-related diseases. In a rat model, ROQUETTE Chlorella sp. (RCs) benefits were investigated on visceral pain and associated inflammatory parameters related to cystitis both induced by cyclophosphamide (CYP). RCs was orally administered every day from day 1-16 (250 and 500 mg/kg body weight). Six hours after an intraperitoneal injection of 200 mg/kg body weight of CYP, body temperature, general behavior, food intake, and body weight were recorded. Twenty-four hours after CYP injection, rats were tested in two behavioral tests, an open field and the aversive light stimulus avoidance conditioning test, to evaluate the influence of pain on general activity and learning ability of rats. After euthanasia, bladders were weighed, their thickness was scored, and the urinary hemoglobin was measured. RCs orally administered at the two dosages significantly reduced visceral pain and associated inflammatory parameters related to cystitis both induced by CYP injection, and improved rat behavior. To conclude, RCs demonstrated beneficial effects against visceral pain and cystitis. [ABSTRACT FROM AUTHOR]

The article focuses findings of a study on mycolactone for therapeutic use against inflammatory disorders. It states that bacterial production of mycolactone in human skin causes a combination of ulcerative, analgesic, and anti-inflammatory effects, and mentions that the minimal structure retaining immunosuppressive activity was a truncated version of mycolactone. It infers translational potential of mycolactone core-derived structures as prospective immunosuppressants.

The article focuses on findings of a study on effects of monoclonal antibodies against GARP/TGF-beta 1 complexes in inhibiting the immunosuppressive activity of human regulatory T cells. It states that two anti-GARP monoclonal antibodies were generated that block the production of the active TGF complexes, and mentions that antibodies recognizing other GARP epitopes did not block active TGF. It infers that blocking anti-GARP antibodies may improve the efficiency of cancer immunotherapy.

Transforming growth factor-β (TGFβ) is a key mediator of fibrogenesis. TGFβ is overexpressed and activated in fibrotic diseases, regulates fibroblast differentiation into myofibroblasts and induces extracellular matrix deposition. Platelet-derived growth factor (PDGF) is also a regulator of fibrogenesis. Some studies showed a link between TGFβ and PDGF in certain fibrotic diseases. TGFβ induces PDGF receptor alpha expression in scleroderma fibroblasts. PDGF-C and -D are the most recently discovered ligands and also play a role in fibrosis. In this study, we report the first link between TGFβ and PDGF-D and -C ligands. In normal fibroblasts, TGFβ down-regulated PDGF-D expression and up-regulated PDGF-C expression at the mRNA and protein levels. This phenomenon is not limited to TGFβ since other growth factors implicated in fibrosis, such as FGF, EGF and PDGF-B, also regulated PDGF-D and PDGF-C expression. Among different kinase inhibitors, only TGFβ receptor inhibitors and the IκB kinase (IKK) inhibitor BMS-345541 blocked the effect of TGFβ. However, activation of the classical NF-κB pathway was not involved. Interestingly, in a model of lung fibrosis induced by either bleomycin or silica, PDGF-D was down-regulated, which correlates with the production of TGFβ and other fibrotic growth factors. In conclusion, the down-regulation of PDGF-D by TGFβ and other growth factors may serve as a negative feedback in the network of cytokines that control fibrosis. [ABSTRACT FROM AUTHOR]

Human Treg and Th clones secrete the latent form of TGF-β, in which the mature TGF-β protein is bound to the latency-associated peptide (LAP), and is thereby prevented from binding to the TGF-β receptor. We previously showed that upon TCR stimulation, human Treg clones but not Th clones produce active TGF-β and bear LAP on their surface. Here, we show that latent TGF-β, i.e. both LAP and mature TGF-β, binds to glycoprotein A repetitions predominant (GARP), a transmembrane protein containing leucine rich repeats, which is present on the surface of stimulated Treg clones but not on Th clones. Membrane localization of latent TGF-β mediated by binding to GARP may be necessary for the ability of Treg to activate TGF-β upon TCR stimulation. However, it is not sufficient as lentiviral-mediated expression of GARP in human Th cells induces binding of latent TGF-β to the cell surface, but does not result in the production of active TGF-β upon stimulation of these Th cells. [ABSTRACT FROM AUTHOR]

From cancerous and non-cancerous patients, we derived stable clones of CD4 Treg, defined as clones that expressed high CD25 at rest, were anergic in vitro, and suppressed the proliferation of co-cultured CD4 cells. A conserved region of FOXP3 intron 1 was demethylated in all Treg clones, whereas it was methylated in non-regulatory Th and CTL clones. In our panel of human clones, this stable epigenetic mark correlated better with suppressive activity than did FOXP3 mRNA or protein expression. We used expression microarrays to compare Treg and Th clones after activation, which is required for suppressive function. The transcriptional profile that is specific of activated Treg clones includes a TGF-β signature. Both activated Treg and Th clones produced the latent form of TGF-β. However, SMAD2 phosphorylation was observed after activation in the Treg but not in the Th clones, indicating that only activated Treg clones produced the bioactive form of TGF-β. A TGF-β signature was also displayed by a Th clone 'suppressed' by a Treg clone. In conclusion, the hallmark of our panel of activated human Treg clones is to produce bioactive TGF-β which has autocrine actions on Tregs and can have paracrine actions on other T cells. [ABSTRACT FROM AUTHOR]

Interleukin 27 (IL-27) was first characterized as a proinflammatory cytokine with T helper type 1–inducing activity. However, subsequent work has demonstrated that mice deficient in IL-27 receptor (IL-27Rα) show exacerbated inflammatory responses to a variety of challenges, suggesting that IL-27 has important immunoregulatory functions in vivo. Here we demonstrate that IL-27Rα-deficient mice were hypersusceptible to experimental autoimmune encephalomyelitis and generated more IL-17-producing T helper cells. IL-27 acted directly on effector T cells to suppress the development of IL-17-producing T helper cells mediated by IL-6 and transforming growth factor-β. This suppressive activity was dependent on the transcription factor STAT1 and was independent of interferon-γ. Finally, IL-27 suppressed IL-6-mediated T cell proliferation. These data provide a mechanistic explanation for the IL-27-mediated immune suppression noted in several in vivo models of inflammation. [ABSTRACT FROM AUTHOR]

The cancer-germline gene MAGE-3 codes for tumor-specific anti- gens recognized on many tumors by T lymphocytes. A MAGE-3 antigen presented by HLA-A1 has been used in several vaccination trials on metastatic melanoma patients. Only a small minority of patients have shown evidence of tumor regression. Attempts to correlate the tumor rejections with the cytotoxic T lymphocyte (CTL) response against the vaccine have been hampered by the low level of these responses. In noncancerous individuals, the frequency of the T cell precursors against antigen MAGE-3.A1 is ≈4 x 10-7 CD8 T cells. The diversity of the T cell receptor repertoire of these anti-MAGE-3.A1 precursors was analyzed in one individual. The results indicate that it is very likely that the repertoire comprises >100 clonotypes. On this basis, it is possible to use not only the frequency of CTL precursors in the blood but also the presence of dominant clonotypes to ascertain in patients the existence of anti-AGE-3.A1 responses as low as 10-6 of CD8. With this approach, we observed a correlation between tumor regression and anti-MAGE-3.A1 responses in patients vaccinated with a recombinant virus encoding the antigen and also in patients vaccinated with peptide-pulsed dendritic cells. In contrast for patients showing tumor regression after vaccination with peptide alone, CTL responses were almost never observed. It is possible that even those CTL responses that are below our present detection level can trigger a sequence of events that leads to tumor regression. [ABSTRACT FROM AUTHOR]

IL-27, a novel heterodimeric cytokine produced by antigen-presenting cells, signals through the T cell cytokine receptor (TCCR)[sup/wsx-1] expressed on naive CD4[sup+] T cells and natural killer cells. TCCR[sup/wsx-1] deficiency results in delayed T helper type I (TH1) development through an unresolved mechanism. We report here that 11.-27 stimulation in developing murine T helper cells potently induces the expression of the major T[subH]l-Specific transcription factor T-bet and its downstream target IL-12R/32, independently of IFNγ. In addition, IL-27 suppresses basal expression of GATA-3, the critical TH2-specific transcription factor that inhibits TH1 development by down-regulating signal transducer and activator of transcription (Stat) 4. IL-27 signaling through TCCR[sup/wsx-1] induces phosphorylation of Stat1, Stat3, Stat4, and Stat5. Stat1 is required for suppression of GATA-3, but T-bet induction by IL-27 can also be mediated through a Statl-independent pathway. Despite its TH1like signaling profile, IL-27 is not sufficient to drive the differentiation of CD4[sup+] T cells into IFNγ-producing cells. Similarly, IL-27 induces T-bet expression in primary natural killer cells, but this does not result in an increase of IFNγ production or cytotoxic activity. Therefore, although 11.-27 is unable to drive IFNγ, production on its own, it plays an important role in the early steps of T[subH]1 commitment by contributing in a paracrine manner to the control of 1L-12 responsiveness. [ABSTRACT FROM AUTHOR]