Pathogenic CD4 Research Articles

Epitope Hierarchy in Type 1 Diabetes Pathogenesis.

Type 1 diabetes (T1D) is an autoimmune disease mediated by T cells destroying insulin-producing β cells. Identifying the antigenic epitopes targeted by autoreactive T cells is crucial for understanding pathogenesis, detecting biomarkers, and developing immunotherapies. This paper covers T-cell epitopes in T1D, focusing on pre-proinsulin and hybrid insulin peptides (HIPs) as major autoantigens. Substantial evidence highlights epitopes in the insulin B-chain and C-peptide as dominant targets for pathogenic CD4 and CD8 T cells infiltrating the islets. HIPs, formed by proinsulin fragments ligated to other peptides, constitute a novel class of epitopes detected in human and mouse islets. In addition, the paper also examines neoepitopes arising from posttranslational modifications, splice variants, and defective ribosomal products. A key challenge is differentiating genuinely pathogenic epitopes driving disease from nonpathogenic mimotopes. Identifying any essential, indispensable epitopes among this array could enable the development of antigen-specific immunotherapies targeting the root causative factors underlying T1D.

Preclinical characterization of MTX-101: a novel bispecific CD8 Treg modulator that restores CD8 Treg functions to suppress pathogenic T cells in autoimmune diseases

IntroductionRegulatory CD8 T cells (CD8 Treg) are responsible for the selective killing of self-reactive and pathogenic CD4 T cells. In autoimmune disease, CD8 Treg may accumulate in the peripheral blood but fail to control the expansion of pathogenic CD4 T cells that subsequently cause tissue destruction. This CD8 Treg dysfunction is due in part to the expression of inhibitory killer immunoglobulin-like receptors (KIR; KIR2DL isoforms [KIR2DL1, KIR2DL2, and KIR2DL3]); these molecules serve as autoimmune checkpoints and limit CD8 Treg activation.MethodsHere we describe the pre-clinical characterization of MTX-101, a bispecific antibody targeting inhibitory KIR and CD8. Using human peripheral blood mononuculear cells (PBMC) derived from healthy donors and autoimmune patients, humanized mouse models, and human derived tissue organoids, we evaluated the molecular mechanisms and functional effects of MTX-101.ResultsBy binding to KIR, MTX-101 inhibited KIR signaling that can restore CD8 Treg ability to eliminate pathogenic CD4 T cells. MTX-101 bound and activated CD8 Treg in human peripheral blood mononuclear cells (PBMC), resulting in increased CD8 Treg cytolytic capacity, activation, and prevalence. Enhancing CD8 Treg function with MTX-101 reduced pathogenic CD4 T cell expansion and inflammation, without increasing pro-inflammatory cytokines or activating immune cells that express either target alone. MTX-101 reduced antigen induced epithelial cell death in disease affected tissues, including in tissue biopsies from individuals with autoimmune disease (i.e., celiac disease, Crohn’s disease). The effects of MTX-101 were specific to autoreactive CD4 T cells and did not suppress responses to viral and bacterial antigens. In a human PBMC engrafted Graft versus Host Disease (GvHD) mouse model of acute inflammation, MTX-101 bound CD8 Treg and delayed onset of disease. MTX-101 induced dose dependent binding, increased prevalence and cytolytic capacity of CD8 Treg, as well as increased CD4 T cell death. MTX-101 selectively bound CD8 Treg without unwanted immune cell activation or increase of pro-inflammatory serum cytokines and exhibited an antibody-like half-life in pharmacokinetic and exploratory tolerability studies performed using IL-15 transgenic humanized mice with engrafted human lymphocytes, including CD8 Treg at physiologic ratios.ConclusionCollectively, these data support the development of MTX-101 for the treatment of autoimmune diseases.

OCA-B promotes pathogenic maturation of stem-like CD4 + T cells and autoimmune demyelination.

Stem-like T cells selectively contribute to autoimmunity, but the activities that promote their pathogenicity are incompletely understood. Here, we identify the transcription coregulator OCA-B as a driver of the pathogenic maturation of stem-like CD4 + T cell to promote autoimmune demyelination. Using a human multiple sclerosis (MS) patient dataset, we show that POU2AF1 , the gene encoding OCA-B, is elevated in CD4 + T cells from secondary-progressive MS patient lesions. We show that T cell-intrinsic OCA-B loss protects mice from experimental autoimmune encephalomyelitis (EAE) while preserving responses to viral CNS infection. In EAE models driven by antigen reencounter, OCA-B deletion nearly eliminates CNS infiltration, proinflammatory cytokine production and clinical disease. CNS OCA-B-expressing CD4 + T of mice with EAE express an encephalitogenic gene program and preferentially confer disease. In a relapsing-remitting EAE model, OCA-B loss protects mice specifically at relapse. During remission, OCA-B promotes the expression of Tcf7 , Slamf6 , and Sell in proliferating CNS T cell populations. At relapse timepoints, OCA-B loss results in both the accumulation of an immunomodulatory CD4 + T cell population expressing Ccr9 and Bach2 , and loss of pro-inflammatory gene expression from Th17 cells. These results identify OCA-B as a driver of pathogenic CD4 + T cells.

MiR-147-3p in pathogenic CD4 T cells controls chemokine receptor expression for the development of experimental autoimmune diseases

Incomplete Freund's adjuvant (IFA) has long been used to trigger autoimmune diseases in animal models, such as experimental autoimmune encephalitis and collagen-induced arthritis. However, the molecular mechanisms that control CD4 T cell effector functions and lead to the development of autoimmune diseases are not well understood. A self-antigen and heat-killed Mycobacterium tuberculosis emulsified in IFA augmented the activation of CD4 T cells, leading to the differentiation of pathogenic CD4 T cells in the draining lymph nodes. In contrast, IFA emulsification did not elicit Foxp3+ regulatory T cell expansion. We found that pathogenic Th1 cells expressed miR-147-3p, which targets multiple genes to affect T cell function. Finally, miR-147-3p expressed in CXCR6+SLAMF6– Th1 cells was required for the onset of neurological symptoms through the control of CXCR3 expression. Our findings demonstrate that miR-147-3p expressed in pathogenic CD4 T cells regulates the migratory potential in peripheral tissues and impacts the development of autoimmune diseases.

Regulatory CD4+ T cells redirected against pathogenic CD8+ T cells protect NOD mice from development of autoimmune diabetes.

In this study, we report a novel therapeutic approach redirecting antigen-specific CD4+ T cells recognizing a hybrid insulin peptide (BDC2.5 T cell receptor (TCR) transgenic CD4+ T cells) to attract and suppress islet-specific CD8+ T cells T cells in the non-obese diabetic (NOD) mouse model, and prevent the development of autoimmune diabetes. Purified BDC2.5 CD4+ T cells were induced to differentiate into regulatory T cells (Tregs). The Tregs were then electroporated with mRNA encoding chimeric human β2 microglobulin (hβ2m) covalently linked to insulin B chain amino acids 15-23 (designated INS-eTreg) or islet-specific glucose-6-phosphatase related protein (IGRP) peptide 206-214 (designated IGRP-eTreg). Immunoregulatory functions of these engineered regulatory T cells (eTregs) were tested by in vitro assays and in vivo co-transfer experiments with β-cell-antigen-specific CD8+ T cells in NOD.Scid mice or by adoptive transfer into young, pre-diabetic NOD mice. These eTregs were phenotyped by flow cytometry, and shown to have high expression of FoxP3, as well as other markers of Treg function, including IL-10. They suppressed polyclonal CD4+ T cells and antigen-specific CD8+ T cells (recognizing insulin or IGRP), decreasing proliferation and increasing exhaustion and regulatory markers in vitro. In vivo, eTregs reduced diabetes development in co-transfer experiments with pathogenic antigen-specific CD8+ T cells (INS-CD8+ or IGRP-CD8+ cells) into NOD.Scid mice. Finally, when the eTreg were injected into young NOD mice, they reduced insulitis and prevented spontaneous diabetes in the recipient mice. Our results suggest a novel therapeutic strategy to protect NOD mice by targeting antigen-specific cytotoxic CD8+ T cells, using redirected antigen-specific CD4+ Treg cells, to suppress autoimmune diabetes. This may suggest an innovative therapy for protection of people at risk of development of type 1 diabetes.

CD8+T cell infiltration-associated barrier function of brain endothelial cells is enhanced by Astragalus polysaccharides via inhibiting PI3K/AKT signaling pathway.

Pathogenic CD8+T cells play an essential role in neuroinflammation and neural injury, which leads to the progression of inflammatory neurological disorders. Thus, blocking the infiltration of CD8+T cells is necessary for the treatment of neuroinflammatory diseases. Our previous study demonstrated that Astragalus polysaccharides (APS) could significantly reduce the infiltration of CD8+T cells in experimental autoimmune encephalomyelitis (EAE) mice. However, the mechanism by which APS suppress CD8+T cell infiltration remains elusive. In this study, we further found that APS could reduce the CD8+T cell infiltration in EAE and lipopolysaccharide (LPS)-induced neuroinflammatory model. Furthermore, we established the mouse brain endothelial cell (bEnd.3) inflammatory injury model by interleukin-1β (IL-1β) or LPS in vitro. The results showed that APS treatment downregulated the expression of vascular cell adhesion molecule1 (VCAM1) to decrease the adhesion of CD8+T cells to bEnd.3 cells. APS also upregulated the expression of zonula occluden-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) to reduce the trans-endothelial migration of CD8+T cells. The PI3K/AKT signaling pathway might mediate this protective effect of APS on bEnd.3 cells against inflammatory injury. In addition, we demonstrated the protective effect of APS on the integrity of brain endothelial cells in an LPS-induced neuroinflammatory model. In summary, our results indicate that APS can reduce peripheral CD8+T cell infiltration via enhancing the barrier function of brain endothelial cells, it may be a potential for the prevention of neuroinflammatory diseases.

CYP7B1 deficiency impairs myeloid cell activation in autoimmune disease of the central nervous system.

Dysregulation of cholesterol metabolism underlies neurodegenerative disease and is increasingly implicated in neuroinflammatory diseases, such as multiple sclerosis (MS). Cytochrome P450 family 7 subfamily B member 1 (CYP7B1) is a key enzyme in alternative cholesterol metabolism. A recessive mutation in the gene CYP7B1 is known to cause a neurodegenerative disease, hereditary spastic paraplegia type 5 and oxysterol accumulation. However, the role of CYP7B1 in neuroinflammation has been little revealed. In this study, we induced experimental autoimmune encephalomyelitis (EAE), as a murine model of MS, using CYP7B1 homozygous knockout (KO) mice. We found that CYP7B1 deficiency can significantly attenuate EAE severity. CYP7B1 deficiency is sufficient to reduce leukocyte infiltration into the central nervous system, suppress proliferation of pathogenic CD4+ T cells, and decrease myeloid cell activation during EAE. Additionally, live-animal imaging targeting translocator protein expression, an outer mitochondrial membrane protein biomarker of neuroinflammation, showed that CYP7B1 deficiency results in suppressed neuroinflammation. Using human monocyte-derived microglia-like cellular disease model and primary microglia of CYP7B1 KO mice, we also found that activation of microglia of CYP7B1 deficiency was impaired. These cumulative results suggest that CYP7B1 can regulate neuroinflammation, thus providing potential new targets for therapeutic intervention.

CD4+ T cells reactive to a hybrid peptide from insulin-chromogranin A adopt a distinct effector fate and are pathogenic in autoimmune diabetes

T cell-mediated islet destruction is a hallmark of autoimmune diabetes. Here, we examined the dynamics and pathogenicity of CD4+ Tcell responses to four different insulin-derived epitopes during diabetes initiation in non-obese diabetic (NOD) mice. Single-cell RNA sequencing of tetramer-sorted CD4+ Tcells from the pancreas revealed that islet-antigen-specific Tcells adopted a wide variety of fates and required XCR1+ dendritic cells for their activation. Hybrid-insulin C-chromogranin A (InsC-ChgA)-specific CD4+ Tcells skewed toward a distinct T helper type 1 (Th1) effector phenotype, whereas the majority of insulin B chain and hybrid-insulin C-islet amyloid polypeptide-specific CD4+ T cells exhibited a regulatory phenotype and early or weak Th1 phenotype, respectively. InsC-ChgA-specific CD4+ Tcells were uniquely pathogenic upon transfer, and an anti-InsC-ChgA:IAg7 antibody prevented spontaneous diabetes. Our findings highlight the heterogeneity of Tcell responses to insulin-derived epitopes in diabetes and argue for the feasibility of antigen-specific therapies that blunts the response of pathogenic CD4+ Tcells causing autoimmunity.

KIR2DL5+CD8+ T cells associate with dietary lipid intake and are active in type 1 diabetes

BackgroundRecent studies have shown that KIR+CD8+ T cells play a role in suppressing autoimmunity by eliminating pathogenic CD4+ T cells. However, their specific role in type 1 diabetes (T1D) remains unclear. MethodsIn this study, we enrolled 108 patients diagnosed with T1D and 86 healthy individuals. We conducted flow cytometric analysis to examine the various subtypes of KIR+CD8+ T cells derived from peripheral blood mononuclear cells. Additionally, CD8+ T cells were isolated from the peripheral blood of T1D patients to assess the functions of different KIR+CD8+ T cell subtypes. To investigate the influence of lipids on the characteristics and activities of these T cell subtypes, the isolated CD8+ T cells were cultured with varying concentrations of palmitic acid (PA). Furthermore, we utilized an NSG (NOD scid gamma) mouse adoptive transfer model to assess the impact of dietary lipid intake on the functionality of KIR2DL5+CD8+ T cells in vivo. ResultsWe observed variations in circulating KIR+CD8+ T cell subtypes between patients with T1D and healthy controls. Notably, we observed a significant negative correlation between the frequencies of circulating KIR+CD8+ T cells and the titers of ZnT8 autoantibodies in individuals with T1D. Among these subtypes, KIR2DL5+CD8+ T cells demonstrated a positive association with dietary fat intake, characterized by increased perforin expression and reduced PD-1 expression. Importantly, KIR2DL5+CD8+ T cells exhibited enhanced proliferative capacity compared to other KIR+CD8+ T cell subsets. Palmitic acid (PA) was found to enhance the activation of KIR2DL5+CD8+ T cells and strengthened their ability to suppress CD4+ T cell proliferation in T1D patients. Moreover, dietary lipid intake significantly enhanced the functionality of KIR2DL5+CD8+ T cells in an NSG mouse adoptive transfer model. ConclusionOur findings suggest that lipid intake enhances the functionality of human KIR2DL5+CD8+ T cells and may offer implications for immunotherapy in T1D.

Tridecylcyclohexane in incomplete Freund's adjuvant is a critical component in inducing experimental autoimmune diseases.

Incomplete Freund's adjuvant (IFA) has been used for many years to induce autoimmune diseases in animal models, including experimental autoimmune encephalitis and collagen-induced arthritis. However, it remains unclear why it is necessary to emulsify autoantigen and heat-killed Mycobacterium tuberculosis (HKMtb) with IFA to induce experimental autoimmune diseases. Here, we found that immunization with self-antigen and HKMtb was insufficient to induce autoimmune diseases in mice. Furthermore, IFA or one of its components, mineral oil, but not mannide monooleate, was required for the development of experimental autoimmune disease. Immunization with autoantigen and HKMtb emulsified in mineral oil facilitated innate immune activation and promoted the differentiation of pathogenic CD4+ T cells, followed by their accumulation in neuronal tissues. Several water-soluble hydrocarbon compounds were identified in mineral oil. Of these, immunization with HKMtb and autoantigen emulsified with the same amount of hexadecane or tridecylcyclohexane as mineral oil induced the development of experimental autoimmune encephalitis. In contrast, immunization with HKMtb and autoantigen emulsified with tridecylcyclohexane, but not hexadecane, at doses equivalent to those found in mineral oil, resulted in neuronal dysfunction. These data indicate that tridecylcyclohexane in mineral oil is a critical component in the induction of experimental autoimmune disease.

Mucosal signatures of pathogenic T cells in HLA-B*27+ anterior uveitis and axial spondyloarthritis.

HLA-B*27 was one of the first HLA alleles associated with an autoimmune disease, i.e., axial spondyloarthritis (axSpA) and acute anterior uveitis (B27AAU), which cause joint and eye inflammation, respectively. Gastrointestinal inflammation has been suggested as a trigger of axSpA. We recently identified a bacterial peptide (YeiH) that can be presented by HLA-B*27 to expanded public T cell receptors (TCRs) in the joint in axSpA and the eye in B27AAU. While YeiH is present in enteric microbiota and pathogens, additional evidence that pathogenic T cells in HLA-B*27-associated autoimmunity may have had a prior antigenic encounter within the gastrointestinal tract remains lacking. Here, we analyze ocular, synovial, and blood T cells in B27AAU and axSpA, showing that YeiH-specific CD8 T cells express a mucosal gene set and surface proteins consistent with intestinal differentiation, including CD161, integrin α4β7, and CCR6. In addition, we find an expansion of YeiH-specific CD8 T cells in the blood of axSpA and B27AAU over healthy controls, whereas influenza-specific CD8 T cells were equivalent across groups. Lastly, we demonstrate the dispensability of TRBV9 for antigen recognition. Collectively, our data suggest that, in HLA-B27-associated autoimmunity, early antigen exposure and differentiation of pathogenic CD8 T cells may occur in enteric organs.

P-015 Impaired spermatogenesis in colitis: the role of interferon-γ mediated ferroptosis in sertoli cells by colitic CD4+ T cells

Abstract Study question Does colitis have an impact on spermatogenesis and what could be the potential mechanism? Summary answer Colitis causes sertoli cell ferroptosis and disrupts spermatogenesis in mice due to the migration of colitic CD4+ T cells that produce interferon-γ. What is known already In recent years, there has been a significant increase in rheumatic and inflammatory diseases. Epidemiological data reveals that dysregulated immune conditions can directly or indirectly impact male fertility and sexual function in patients of reproductive age. Inflammatory bowel disease (IBD), which encompasses Crohn’s disease and ulcerative colitis, is a chronic, recurring gastrointestinal inflammatory disorder characterized by bloody stools and weight loss. A study from a Swedish national cohort showed that IBD patients had diminished sperm fertility and increased sperm DNA fragmentation compared to healthy individuals. However, the precise mechanisms underlying male fertility problems in IBD remain unclear. Study design, size, duration In this study, C57BL/6 mice were kept under specific pathogen-free conditions. A murine colitis model that simulates human colitis histological features and symptoms was created using Dextran Sulfate Sodium (DSS). To establish the model, 2-2.5% DSS was added to the mice’s drinking water from days 0 to 7, followed by a three-day recovery period. Participants/materials, setting, methods Testis, epididymis and colon sections were stained with hematoxylin and eosin for histological analysis. The localization and phenotype of infiltrated lymphocytes in epididymis and testis were studied by immunostaining and flow cytometry. Sperm functions including motility, viability, and DNA integrity were assessed by standard assays. Iron, malondialdehyde, and reactive oxygen species (ROS) levels were analysed by commercial kit. Main results and the role of chance Colitis was found to impair male fertility in DSS-induced colitic mice, causing testis and epididymis tissue damage along with inflammatory cell infiltration. Colitis altered the immune cell phenotypes in the testis and epididymis. The proportion and absolute cell count of CD4+ T cells and CD19+ B cells increased after colon inflammation. Testicular sertoli cells in colitic mice exhibited ferroptosis, characterized by increased levels of iron deposition, malondialdehyde, and ROS. We assessed sperm parameters from the cauda epididymis of mice. Compared to the control group, there were significant reduction in sperm concentration, motility, viability and DNA integrity in the group with murine colitis induction. Consistently, we observed lower numbers of active pups from the fathers of the colitis group compared to control mice. CD4+ T cells with interferon-γ producing capabilities accumulated in the testes of colitis mice. Leukocyte flow cytometric analysis and parabiotic mouse model further demonstrated that colitis promoted pathogenic CD4+ T cells migration to the testis through circulation. The treatment of anti-CD4 antibody, anti-interferon-γ antibody or ferroptosis inhibitor can attenuate the colitis-associated testis pathologies. Limitations, reasons for caution Our study was conducted exclusively in mice. The pathogenic effect and the corresponding mechanism of colitis on male fertility in humans still needs to be confirmed. Wider implications of the findings Our team identified the mechanism linking dysregulated gut immune cell activity to testicular dysfunction. By identifying specific molecules on colitic immune cells, which allow their infiltration into the testis, may pave the way for a new therapeutic approach potentially improving the prognosis of colitis and related fertility impairments. Trial registration number not applicable

Scavengers in islets fuel diabetic autoimmunity

Autoreactive lymphocytes that infiltrate the pancreatic islet environment and target β cells are primary drivers of type 1 diabetes. In this issue of Immunity, Srivastava etal.1 examine the role of the islet microenvironment in autoimmunity and find that the scavenging receptor CXCL16 on islet-resident macrophages uptakes oxidized low-density lipoproteins and promotes the differentiation and survival of infiltrating pathogenic CD8+ Tcells.

First-in-human, double-blind, randomized phase 1b study of peptide immunotherapy IMCY-0098 in new-onset type 1 diabetes: an exploratory analysis of immune biomarkers

BackgroundIMCY-0098, a synthetic peptide developed to halt disease progression via elimination of key immune cells in the autoimmune cascade, has shown a promising safety profile for the treatment of type 1 diabetes (T1D) in a recent phase 1b trial. This exploratory analysis of data from that trial aimed to identify the patient biomarkers at baseline associated with a positive response to treatment and examined the associations between immune response parameters and clinical efficacy endpoints (as surrogates for mechanism of action endpoints) using an artificial intelligence-based approach of unsupervised explainable machine learning.MethodsWe conducted an exploratory analysis of data from a phase 1b, dose-escalation, randomized, placebo-controlled study of IMCY-0098 in patients with recent-onset T1D. Here, a panel of markers of T cell activation, memory T cells, and effector T cell response were analyzed via descriptive statistics. Artificial intelligence-based analyses of associations between all variables, including immune responses and clinical responses, were performed using the Knowledge Extraction and Management (KEM®) v 3.6.2 analytical platform.ResultsThe relationship between all available patient data was investigated using unsupervised machine learning implemented in the KEM® environment. Of 15 associations found for the dose C group (450 μg subcutaneously followed by 3 × 225 μg subcutaneously), seven involved human leukocyte antigen (HLA) type, all of which identified improvement/absence of worsening of disease parameters in DR4+ patients and worsening/absence of improvement in DR4− patients. This association with DR4+ and non-DR3 was confirmed using the endpoints normalized area under the curve C-peptide from mixed meal tolerance tests where presence of DR4 HLA haplotype was associated with an improvement in both endpoints. Exploratory immune analysis showed that IMCY-0098 dose B (150 μg subcutaneously followed by 3 × 75 μg subcutaneously) and dose C led to an increase in presumed/potentially protective antigen-specific cytolytic CD4+ T cells and a decrease in pathogenic CD8+ T cells, consistent with the expected mechanism of action of IMCY-0098. The analysis identified significant associations between immune and clinical responses to IMCY-0098.ConclusionsPromising preliminary efficacy results support the design of a phase 2 study of IMCY-0098 in patients with recent-onset T1D.Trial registrationClinicalTrials.gov NCT03272269; EudraCT: 2016–003514-27.

A pathologically expanded, clonal lineage of IL-21-producing CD4+ T cells drives inflammatory neuropathy.

Inflammatory neuropathies, which include chronic inflammatory demyelinating polyneuropathy (CIDP) and Guillain Barré syndrome (GBS), result from autoimmune destruction of the PNS and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we used paired single-cell RNA-Seq (scRNA-Seq) and single-cell T cell receptor-sequencing (scTCR-Seq) of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21-expressing CD4+ T cells that were clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells consisted of 2 transcriptionally distinct expanded cell populations, which expressed genes associated with T follicular helper (Tfh) and T peripheral helper (Tph) cell subsets. Remarkably, TCR clonotypes were shared between these 2 IL-21-expressing cell populations, suggesting a common lineage differentiation pathway. Finally, we demonstrated that IL-21 receptor-KO (IL-21R-KO) mice were protected from neuropathy development and had decreased immune infiltration into peripheral nerves. IL-21 signaling upregulated CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

Neutrophil-mediated hypoxia drives pathogenic CD8+ T cell responses in cutaneous leishmaniasis.

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8+ T cell responses mediate disease. Although these responses originate in the lymph node, we found that expression of the cytolytic effector molecule granzyme B was restricted to lesional CD8+ T cells in Leishmania-infected mice, suggesting that local cues within inflamed skin induced cytolytic function. Expression of Blimp-1 (Prdm1), a transcription factor necessary for cytolytic CD8+ T cell differentiation, was driven by hypoxia within the inflamed skin. Hypoxia was further enhanced by the recruitment of neutrophils that consumed oxygen to produce ROS and ultimately increased the hypoxic state and granzyme B expression in CD8+ T cells. Importantly, lesions from patients with cutaneous leishmaniasis exhibited hypoxia transcription signatures that correlated with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8+ T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as for other inflammatory skin diseases in which cytolytic CD8+ T cells contribute to pathogenesis.

PDIA3 orchestrates effector T cell program by serving as a chaperone to facilitate the non-canonical nuclear import of STAT1 and PKM2

Dysregulated T cell activation underpins the immunopathology of rheumatoid arthritis (RA), yet the machineries that orchestrate T cell effector program remain incompletely understood. Herein, we leveraged bulk and single-cell RNA sequencing data from RA patients and validated protein disulfide-isomerase A3 (PDIA3) as a potential therapeutic target. PDIA3 is remarkably upregulated in pathogenic CD4 T cells derived from RA patients and positively correlates with C-reactive protein (CRP) level and disease activity score 28 (DAS28). Pharmacological inhibition or genetic ablation of PDIA3 alleviates RA-associated articular pathology and autoimmune responses. Mechanistically, T cell receptor (TCR) signaling triggers intracellular calcium flux to activate NFAT1, a process that is further potentiated by Wnt5a under RA settings. Activated NFAT1 then directly binds to the Pdia3 promoter to enhance the expression of PDIA3, which complexes with STAT1 or PKM2 to facilitate their nuclear import for transcribing Th1 and Th17 lineage-related genes, respectively. This non-canonical regulatory mechanism likely occurs under pathological conditions as PDIA3 could only be highly induced following aberrant external stimuli. Together, our data support that targeting PDIA3 is a vital strategy to mitigate autoimmune diseases, such as RA, in clinical settings.

Mesenchymal Stem Cells from Mouse Hair Follicles Inhibit the Development of Type 1 Diabetes.

Mesenchymal stem cells (MSCs) are known for their immunosuppressive properties. Based on the demonstrated anti-inflammatory effect of mouse MSCs from hair follicles (moMSCORS) in a murine wound closure model, this study evaluates their potential for preventing type 1 diabetes (T1D) in C57BL/6 mice. T1D was induced in C57BL/6 mice by repeated low doses of streptozotocin. moMSCORS were injected intravenously on weekly basis. moMSCORS reduced T1D incidence, the insulitis stage, and preserved insulin production in treated animals. moMSCORS primarily exerted immunomodulatory effects by inhibiting CD4+ T cell proliferation and activation. Ex vivo analysis indicated that moMSCORS modified the cellular immune profile within pancreatic lymph nodes and pancreatic infiltrates by reducing the numbers of M1 pro-inflammatory macrophages and T helper 17 cells and upscaling the immunosuppressive T regulatory cells. The proportion of pathogenic insulin-specific CD4+ T cells was down-scaled in the lymph nodes, likely via soluble factors. The moMSCORS detected in the pancreatic infiltrates of treated mice presumably exerted the observed suppressive effect on CD4+ through direct contact. moMSCORS alleviated T1D symptoms in the mouse, qualifying as a candidate for therapeutic products by multiple advantages: non-invasive sampling by epilation, easy access, permanent availability, scalability, and benefits of auto-transplantation.

CXCL16-dependent scavenging of oxidized lipids by islet macrophages promotes differentiation of pathogenic CD8+ T cells in diabetic autoimmunity

The pancreatic islet microenvironment is highly oxidative, rendering β cells vulnerable to autoinflammatory insults. Here, we examined the role of islet resident macrophages in the autoimmune attack that initiates type 1 diabetes. Islet macrophages highly expressed CXCL16, a chemokine and scavenger receptor for oxidized low-density lipoproteins (OxLDLs), regardless of autoimmune predisposition. Deletion of Cxcl16 in nonobese diabetic (NOD) mice suppressed the development of autoimmune diabetes. Mechanistically, Cxcl16 deficiency impaired clearance of OxLDL by islet macrophages, leading to OxLDL accumulation in pancreatic islets and a substantial reduction in intra-islet transitory (Texint) CD8+ Tcells displaying proliferative and effector signatures. Texint cells were vulnerable to oxidative stress and diminished by ferroptosis; PD-1 blockade rescued this population and reversed diabetes resistance in NOD.Cxcl16-/- mice. Thus, OxLDL scavenging in pancreatic islets inadvertently promotes differentiation of pathogenic CD8+ Tcells, presenting a paradigm wherein tissue homeostasis processes can facilitate autoimmune pathogenesis in predisposed individuals.

Identification of master regulator genes controlling pathogenic CD4+ T cell fate in inflammatory bowel disease through transcriptional network analysis

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory conditions of the gastrointestinal tract associated with multiple pathogenic factors, including dysregulation of the immune response. Effector CD4+ T cells and regulatory CD4+ T cells (Treg) are central players in maintaining the balance between tolerance and inflammation. Interestingly, genetic modifications in these cells have been implicated in regulating the commitment of specific phenotypes and immune functions. However, the transcriptional program controlling the pathogenic behavior of T helper cells in IBD progression is still unknown. In this study, we aimed to find master transcription regulators controlling the pathogenic behavior of effector CD4+ T cells upon gut inflammation. To achieve this goal, we used an animal model of IBD induced by the transfer of naïve CD4+ T cells into recombination-activating gene 1 (Rag1) deficient mice, which are devoid of lymphocytes. As a control, a group of Rag1−/− mice received the transfer of the whole CD4+ T cells population, which includes both effector T cells and Treg. When gut inflammation progressed, we isolated CD4+ T cells from the colonic lamina propria and spleen tissue, and performed bulk RNA-seq. We identified differentially up- and down-regulated genes by comparing samples from both experimental groups. We found 532 differentially expressed genes (DEGs) in the colon and 30 DEGs in the spleen, mostly related to Th1 response, leukocyte migration, and response to cytokines in lamina propria T-cells. We integrated these data into Gene Regulatory Networks to identify Master Regulators, identifying four up-regulated master gene regulators (Lef1, Dnmt1, Mybl2, and Jup) and only one down-regulated master regulator (Foxo3). The altered expression of master regulators observed in the transcriptomic analysis was confirmed by qRT-PCR analysis and found an up-regulation of Lef1 and Mybl2, but without differences on Dnmt1, Jup, and Foxo3. These two master regulators have been involved in T cells function and cell cycle progression, respectively. We identified two master regulator genes associated with the pathogenic behavior of effector CD4+ T cells in an animal model of IBD. These findings provide two new potential molecular targets for treating IBD.