Potential Role In Autoimmunity Research Articles

The prevalence of thyroid function test abnormalities and serum thyroid autoantibodies in vitiligo and alopecia areata patients in Saudi Arabian population

Background: Alopecia areata (AA) and vitiligo are immune-mediated inflammatory diseases characterized by hair loss and depigmented macules, respectively. It is often associated with other autoimmune conditions especially with autoimmune thyroid disorders indicating a potential role of autoimmunity in its development. Methods: A 222 patients, 113 AA and 109 vitiligo diagnosed, were retrospectively reviewed. We analyzed TG-Ab, TPO-Ab, Thyroid function tests (free T3, free T4, and TSH) in all patients. Results: In vitiligo patients, 11% (n=12) had elevated levels of anti-TG levels and 26.6% (n=29) had elevated levels of anti-TPO, Thyroid hormonal abnormalities were found in 15.6% (n=17) of vitiligo patients, and fT4 was elevated in 1.83% (n=2) patients. Within AA patients, 15.9% (n=18) had anti-TG elevation and 23.9% (n=27) had anti-TPO elevation, thyroid hormonal abnormalities were found in 16.8% (n=19), and fT4 was high in 0.88% (n=1) patient. No significant difference was found between the two groups for all measured parameters. No statistically significant correlation between the gender of the patients and the diagnosis, thyroid hormonal test, and thyroid autoantibody levels could be detected (p>0.05) Conclusions: In our study, impaired thyroid functions and thyroid autoantibodies in vitiligo and AA patients were identified at similar rates of the previous studies. Moreover, we could not find differences in comparison to other ethnicities.

Shared Pathogenicity Features and Sequences between EBV, SARS-CoV-2, and HLA Class I Molecule-binding Motifs with a Potential Role in Autoimmunity.

Epstein-Barr virus (EBV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are extraordinary in their ability to activate autoimmunity as well as to induce diverse autoimmune diseases. Here we reviewed the current knowledge on their relation. Further, we suggested that molecular mimicry could be a possible common mechanism of autoimmunity induction in the susceptible individuals infected with SARS-CoV-2. Molecular mimicry between SARS-CoV-2 and human proteins, and EBV and human proteins, are present. Besides, relation of the pathogenicity associated with both coronavirus diseases and EBV supports the notion. As a proof-of-the-concept, we investigated 8mer sequences with shared 5mers of SARS-CoV-2, EBV, and human proteins, which were predicted as epitopes binding to the same human leukocyte antigen (HLA) supertype representatives. We identified significant number of human peptide sequences with predicted-affinities to the HLA-A*02:01 allele. Rest of the peptide sequences had predicted-affinities to the HLA-A*02:01, HLA-B*40:01, HLA-B*27:05, HLA-A*01:01, and HLA-B*39:01 alleles. Carriers of these serotypes can be under a higher risk of autoimmune response induction upon getting infected, through molecular mimicry-based mechanisms common to SARS-CoV-2 and EBV infections. We additionally reviewed established associations of the identified proteins with the EBV-related pathogenicity and with the autoimmune diseases.

Partial RAG deficiency induces dysregulated peripheral lymphocyte development and humoral tolerance defect with accumulation of T-bet+ B cells

CD21low CD11c+ T-bethigh B cells are frequently expanded in various autoimmune disorders, indicating their potential role in autoimmunity. Patients with partial RAG deficiency (pRD) are characterized by humoral autoimmunity, suggesting breach in tolerance mechanisms and subsequent expansion of autoreactive B cell clones.By studying B cell development and subset specific BCR repertoires in a cohort of pRD patients, we found that reduced RAG activity impinges on peripheral tolerance. Tolerance defect is a result of the generation of a restricted primary B cell repertoire and associated with persistent antigenic stimulation and an inflammatory milieu with elevated level of B cell activating factor. This unique environment gradually provokes profound B cell dysregulation with widespread activation, and remarkable expansion of CD21low CD11c+ T-bethigh B cells. Self-reactive clones - identified by single cell cloning of paired heavy and light immunoglobulin chains – persist, expand, and undergo somatic diversification.By investigating a mouse model of pRD (rag1R972Q/R972Q), we detected spontaneous expansion of CD11c+ T-bethigh “age associated B cells” (ABCs) in various lymphoid tissues. Gene expression profiling of splenic B cells by single-cell RNA and paired heavy and light immunoglobulin sequencing revealed imprinted alterations in the epigenetic status of peripheral B cells. Our findings demonstrate that B cell compartment in pRD is dominated with the T-bethigh CD21low ABC-like B cells that have a unique gene expression profile and BCR repertoire that may lead to the B cell dysregulation occurring in pRD patients.

The intersection of COVID-19 and autoimmunity.

Acute COVID-19, caused by SARS-CoV-2, is characterized by diverse clinical presentations, ranging from asymptomatic infection to fatal respiratory failure, and often associated with varied longer-term sequelae. Over the past 18 months, it has become apparent that inappropriate immune responses contribute to the pathogenesis of severe COVID-19. Researchers working at the intersection of COVID-19 and autoimmunity recently gathered at an American Autoimmune Related Diseases Association Noel R. Rose Colloquium to address the current state of knowledge regarding two important questions: Does established autoimmunity predispose to severe COVID-19? And, at the same time, can SARS-CoV-2 infection trigger de novo autoimmunity? Indeed, work to date has demonstrated that 10% to 15% of patients with critical COVID-19 pneumonia exhibit autoantibodies against type I interferons, suggesting that preexisting autoimmunity underlies severe disease in some patients. Other studies have identified functional autoantibodies following infection with SARS-CoV-2, such as those that promote thrombosis or antagonize cytokine signaling. These autoantibodies may arise from a predominantly extrafollicular B cell response that is more prone to generating autoantibody-secreting B cells. This Review highlights the current understanding, evolving concepts, and unanswered questions provided by this unique opportunity to determine mechanisms by which a viral infection can be exacerbated by, and even trigger, autoimmunity. The potential role of autoimmunity in post-acute sequelae of COVID-19 is also discussed.

Abstract 11607: Protein Citrullination Landscape of Human Coronary Atherosclerosis

Introduction: Recently, an irreversible enzymatic post-translational modification, citrullination, has been shown to be present in the cardiovascular system (e.g. aorta). Citrullination, in which arginine is converted to citrulline, can alter protein structure and function, and produce autoantigens Hypothesis: Emerging evidence suggest a potential role for autoimmunity in the pathogenesis of atherosclerosis. However, it remains unknown whether of post-translational citrullination of arterial proteins contributes to local inflammatory processes that initiate or accelerate the atherosclerotic process. The aim of this study was to investigate changes in protein citrullination in human left anterior descending (LAD) coronary artery specimens with and without early atherosclerosis obtained from autopsied young adults with no clinical manifestations of coronary disease. Methods: Segments of the mid-LAD from 74 autopsied individuals (age range:15-55 yrs., 75% male, 67% White) were graded by a pathologist for percent of surface area involved with fatty streaks (FS) or fibrous plaque (FP). The frozen samples were homogenized and digested with Lys-C for subsequent proteomic mass-spectrometry using a data-independent acquisition (DIA) proteomic strategy with a hyper-citrullinated spectral library approach and our published CitFinder software. Results: We found 133 differentially expressed proteins (FDR<0.05) between control, FS and FP groups. Among them, 19 citrullinated proteins with 26 modified amino acid residues were identified. Citrullinated peptides from fibrinogen alpha chain (R84) and transgelin (R146) were upregulated in FP samples in comparison to FS and normal samples. Similarly, the citrullination site (R269) on alpha-enolase was significantly increased in the FP samples compared to normal. Interestingly, citrullination (R110) on myosin light polypeptide 6 was downregulated in FP samples. Conclusions: These data represent the most comprehensive interrogation of citrullinated proteins in human arterial samples to-date and suggest a possible association between this modification of several key proteins involved in tight junction, vascular smooth muscle contraction and inflammation and early atherosclerosis.

Immunotherapy for GRIN2A and GRIN2D-related epileptic encephalopathy

BackgroundGRIN-related developmental-epileptic encephalopathies are associated with a spectrum of neurodevelopmental disorders, including intellectual disability, epilepsy including continuous spike-and-wave during sleep syndrome (CSWS), or epilepsy-aphasia spectrum phenotypes such as in Landau-Kleffner syndrome. Efficacy of IVIG treatment was recently reported in a patient with LKS related to GRIN2A mutation. Aim and MethodsWe describe the efficacy of Immunotherapy in 5 consecutive patients (4 males, age range 6 months-13 years) with molecularly confirmed GRIN-related epileptic encephalopathy (4 with GRIN2A- related epilepsy-aphasia spectrum/epileptic encephalopathy with CSWS, accompanied by verbal, communicative and behavioural regression, and one patient with GRIN2D – related infantile developmental-epileptic encephalopathy). All patients had global developmental delay/ intellectual disability in various degrees, and were resistant to anticonvulsants, but none of the patients had frequent clinical seizures. All patients received monthly infusion of IVIG 2 g/ kg for 6 months; 2 patients were also treated with high-dose corticosteroids. ResultsNormalization or near normalization of the EEG was noted in 3 patients, from whom 2 had mild improvement in verbal abilities and communication skills. Perceptual/spatial abilities, as well as executive functions and attention span, remained significantly impaired. Conclusionaccording to this preliminary, open-label study, Immunotherapy may lead to a clinical and electrographic improvement in patients with GRIN-related developmental-epileptic encephalopathies. Further studies to validate the efficacy of immunotherapy and the potential role of autoimmunity in GRIN-related disorders are needed.

Presence of Antibodies Binding to Negative Elongation Factor E in Sarcoidosis.

Sarcoidosis is characterized by multiorgan involvement and granulomatous inflammation. Its origin is unknown and the potential role of autoimmunity has not been sufficiently determined. We investigated the presence of autoantibodies in sarcoidosis using protein array technology. The derivation cohort consisted of patients with sarcoidosis (n = 25) and controls including autoimmune disease and blood donors (n = 246). In addition, we tested a validation cohort including pulmonary sarcoidosis patients (n = 58) and healthy controls (n = 13). Initially, sera of three patients with sarcoidosis were screened using a protein array with 28.000 proteins against controls. Thereby we identified the Negative Elongation Factor E (NELF-E) as an autoantigen. With confirmatory Enzyme-linked Immunosorbent Assay (ELISA)testing, 29/82 patients (35%) with sarcoidosis had antibodies against NELF-E of the Immunoglobulin (Ig) G type, whereas 18/253 (7%) sera of the controls were positive for NELF-E. Clinically, there was an association of the frequency of NELF-E antibody detection with lung parenchymal involvement and corresponding x-ray types. NELF-E autoantibodies are associated with sarcoidosis and should be further investigated.

Genome-wide imputation study identifies novel HLA locus for pulmonary fibrosis and potential role for auto-immunity in fibrotic idiopathic interstitial pneumonia.

BackgroundFibrotic idiopathic interstitial pneumonias (fIIP) are a group of fatal lung diseases with largely unknown etiology and without definitive treatment other than lung transplant to prolong life. There is strong evidence for the importance of both rare and common genetic risk alleles in familial and sporadic disease. We have previously used genome-wide single nucleotide polymorphism data to identify 10 risk loci for fIIP. Here we extend that work to imputed genome-wide genotypes and conduct new RNA sequencing studies of lung tissue to identify and characterize new fIIP risk loci.ResultsWe performed genome-wide genotype imputation association analyses in 1616 non-Hispanic white (NHW) cases and 4683 NHW controls followed by validation and replication (878 cases, 2017 controls) genotyping and targeted gene expression in lung tissue. Following meta-analysis of the discovery and replication populations, we identified a novel fIIP locus in the HLA region of chromosome 6 (rs7887 Pmeta = 3.7 × 10−09). Imputation of classic HLA alleles identified two in high linkage disequilibrium that are associated with fIIP (DRB1*15:01 P = 1.3 × 10−7 and DQB1*06:02 P = 6.1 × 10−8). Targeted RNA-sequencing of the HLA locus identified 21 genes differentially expressed between fibrotic and control lung tissue (Q < 0.001), many of which are involved in immune and inflammatory response regulation. In addition, the putative risk alleles, DRB1*15:01 and DQB1*06:02, are associated with expression of the DQB1 gene among fIIP cases (Q < 1 × 10−16).ConclusionsWe have identified a genome-wide significant association between the HLA region and fIIP. Two HLA alleles are associated with fIIP and affect expression of HLA genes in lung tissue, indicating that the potential genetic risk due to HLA alleles may involve gene regulation in addition to altered protein structure. These studies reveal the importance of the HLA region for risk of fIIP and a basis for the potential etiologic role of auto-immunity in fIIP.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0377-2) contains supplementary material, which is available to authorized users.

TCR γ4δ1-Engineered αβT Cells Exhibit Effective Antitumor Activity

T cell engineering with T cell receptors (TCRs) specific for tumors plays an important role in adoptive T-cell transfer (ATC) therapy for cancer. Here, we present a novel strategy to redirect peripheral blood-derived αβT cells against tumors via TCRγ4δ1 gene transduction. The broad-spectrum anti-tumor activity of TCRδ1 cells in innate immunity is dependent on CDR3δ1. TCRγ4δ1-engineered αβT cells were prepared by lentiviral transduction and characterized by analyzing in vitro and in vivo cytotoxicity to tumors, ability of proliferation and cytokine production, and their potential role in autoimmunity. Results show TCRγ4δ1 genes were transduced to approximately 36% of polyclonal αβT cells. TCRγ4δ1-engineered αβT cells exhibited an effective in-vitro TCRγδ-dependent cytotoxicity against various tumor cells via the perforin-granzyme pathway. They also showed a strong proliferative capacity and robust cytokine production. TCRγ4δ1-engineered αβT cells neither expressed mixed TCR dimers nor bound/killed normal cells in vitro. More importantly, adoptive transfer of TCRγ4δ1-engineered αβT cells into nude mice bearing a human HepG2 cell line significantly suppressed tumor growth. Our results demonstrate a novel role for TCRγ4δ1 in gene therapy and ATC for cancer.

Contribution of autoallergy to the pathogenesis in the NOD mice

The immunoglobulin isotype IgE is commonly associated with allergy. However, its involvement in autoimmune disease in general, and Type 1 diabetes (T1D) in particular, is still not completely clarified, nonetheless IgE has been observed in patients with T1D. In this article, we aimed to elucidate the contribution of IgE in the pathogenesis of the disease in a spontaneous model for T1D, i.e. the NOD mouse. We observed increased levels of IgE in splenic, lymph node and peripheral blood B cells in the NOD mice compared to the control C57BL/6 (B6) mice. No correlation was found between the IgE levels on B cells and those in the sera of these mice, indicating a B cell intrinsic property mediating IgE capture in NOD. Functionally, the B cells from NOD were similar to B6 in rescuing the IgE-mediated immune response via the low affinity receptor CD23 in a transgenic adoptive transfer system. However, the involvement of IgE in diabetes development was clearly demonstrated, as treatment with anti-IgE antibodies delayed the incidence of the diabetes in the NOD mice compared to the PBS treated group. Pancreas sections from a 13-week-old NOD revealed the presence of tertiary lymphoid structures with T cells, B cells, germinal centers and IgE suggesting the presence of autoantigen specific IgE. Our study provides an insight to the commonly overlooked immunoglobulin IgE and its potential role in autoimmunity.

NLRP3 and ASC suppress lupus-like autoimmunity by driving the immunosuppressive effects of TGF-β receptor signalling

ObjectivesThe NLRP3/ASC inflammasome drives host defence and autoinflammatory disorders by activating caspase-1 to trigger the secretion of mature interleukin (IL)-1β/IL-18, but its potential role in autoimmunity is speculative.MethodsWe generated and...

Population-level evidence for an autoimmune etiology of epilepsy.

Epilepsy is a debilitating condition, often with neither a known etiology nor an effective treatment. Autoimmune mechanisms have been increasingly identified. To conduct a population-level study investigating the relationship between epilepsy and several common autoimmune diseases. A retrospective population-based study using claims from a nationwide employer-provided health insurance plan in the United States. Participants were beneficiaries enrolled between 1999 and 2006 (N = 2 518 034). We examined the relationship between epilepsy and 12 autoimmune diseases: type 1 diabetes mellitus, psoriasis, rheumatoid arthritis, Graves disease, Hashimoto thyroiditis, Crohn disease, ulcerative colitis, systemic lupus erythematosus, antiphospholipid syndrome, Sjögren syndrome, myasthenia gravis, and celiac disease. The risk of epilepsy was significantly heightened among patients with autoimmune diseases (odds ratio, 3.8; 95% CI, 3.6-4.0; P < .001) and was especially pronounced in children (5.2; 4.1-6.5; P < .001). Elevated risk was consistently observed across all 12 autoimmune diseases. Epilepsy and autoimmune disease frequently co-occur; patients with either condition should undergo surveillance for the other. The potential role of autoimmunity must be given due consideration in epilepsy so that we are not overlooking a treatable cause.

Chronic autoimmune atrophic gastritis associated with primary hyperparathyroidism: a transversal prospective study

The coexistence of chronic autoimmune atrophic gastritis (CAAG) and primary hyperparathyroidism (PHPT) has been described previously, even if its extent and underlying mechanisms remain poorly understood. We therefore prospectively evaluated this association in two series of patients, one with CAAG and the other with sporadic PHPT. From January 2005 to March 2012, 107 histologically confirmed CAAG patients and 149 PHPT patients were consecutively enrolled. Routine laboratory assays included serum calcium, parathyroid hormone (PTH), plasma gastrin and chromogranin A (CgA). In CAAG patients with high PTH levels, ionized calcium and 25(OH)-vitamin D were evaluated. All CAAG and hypergastrinemic PHPT patients received an upper gastrointestinal endoscopy. Exclusion criteria were familial PHPT, MEN1 syndrome, treatment with proton pump inhibitor drugs, Helicobacter pylori infection and renal failure. Of the 107 CAAG patients, nine (8.4%) had PHPT and 13 (12.1%) had secondary hyperparathyroidism stemming from vitamin D deficiency. Among the 149 PHPT patients, 11 (7.4%) had CAAG. Gastrin and CgA levels were similar in the CAAG patients with vs those without hyperparathyroidism (either primary or secondary), and calcium and PTH levels were similar in the PHPT patients with vs those without CAAG. This study confirms a non-casual association between PHPT and CAAG. The prevalence of PHPT in CAAG patients is threefold that of the general population (8.4 vs 1-3%), and the prevalence of CAAG in PHPT patients is fourfold that of the general population (7.4 vs 2%). The mechanisms underlying this association remain unknown, but a potential role for autoimmunity is suggested.

Autoimmune Basis of Glaucoma

Glaucoma is one of the leading causes of blindness worldwide. The current view of glaucoma is that it is a multifactorial disease. Elevated IOP is a recognized etiologic factor which can trigger initial damage through biomechanical and ischemic injury to the retinal ganglion cells. However, elevated intraocular pressure cannot be entirely responsible for the development of glaucoma. Accumulating evidence suggests that abnormal immunity may be contributing to the glaucomatous optic neuropathy. Autoimmunity may be responsible for initiating or exacerbating glaucoma. This review provides an evaluation of the potential role of autoimmunity in some patients with glaucoma.

The interferon-inducible HIN-200 gene family in apoptosis and inflammation: Implication for autoimmunity

The Ifi-200/HIN-200 gene family encodes highly homologous human (IFI16, myeloid cell nuclear differentiation antigen, absent in melanoma 2, and IFIX) and murine proteins (Ifi202a, Ifi202b, Ifi203, Ifi204, Ifi205, and Ifi206), which are induced by type I and II interferons (IFN). These proteins have been described as regulators of cell proliferation and differentiation and, more recently, several reports have suggested their involvement in both apoptotic and inflammatory processes. The relevance of HIN-200 proteins in human disease is beginning to be clarified, and emerging experimental data indicate their role in autoimmunity. Autoimmune disorders are sustained by perpetual activation of inflammatory process and a link between autoimmunity and apoptosis has been clearly established. Moreover, the interferon system is now considered as a key player in autoimmune disorders such as systemic lupus erythemathosus, systemic sclerosis, and Sjögren's syndrome, and it is therefore conceivable to hypothesize that HIN-200 may be among the pivotal mediators of IFN activity in autoimmune disease. In particular, the participation of HIN-200 proteins in apoptosis and inflammation could support their potential role in autoimmunity.

Potential Role for Autoimmunity in Non-atopic (Intrinsic) Asthma

Potential Role for Autoimmunity in Non-atopic (Intrinsic) Asthma

Regulatory B lymphocytes in humans: A potential role in autoimmunity

The physiology of B cells has been revolutionized by the attribution of a number of new functions to their already established role in antibody production. Subpopulations of B cells have consequently been delineated, and Breg cells have been identified in mice, but not yet in humans. These Breg cells have the capacity to restrain immune responses and thus prevent pathogenic autoimmunity. Alteration of their function might signal an increased likelihood of disturbed immune homeostasis, making Breg cells an appealing target for immunotherapy, provided a confident characterization can be made. Recent experiments have rekindled the debate on the many alternative functions of B lymphocytes (1), which are no longer thought to have the production of antibodies as their only function. Studies initiated in genetically engineered mice and currently being extended in humans point to their role in antigen presentation (2) in the synovium of patients with rheumatoid arthritis (RA) and to their production of cytokines (3) in the blood of patients with systemic lupus erythematosus (SLE). In addition, their control of lymphoid organogenesis (4) and their function in association with dendritic cells (DCs) in ectopic germinal centers in the salivary glands of patients with primary Sjogren’s syndrome (SS) is consistent with a regulatory role of B lymphocytes. These observations revealed that autoimmune diseases could therefore all be mediated via the longterm activation of B cells (5) and that these cells may play a key role in autoimmunity. This has provided a rationale for therapeutic strategies that alter B cell survival (for review, see refs. 6 and 7). Furthermore, the diversity of their new properties has yielded the delineation of B cell populations into phenotypically unique and functionally distinct subsets. The distribution of these subsets is altered in the blood of patients with autoimmune disease (for review, see ref. 8), and the sequence of their return after therapeutic B cell depletion is abnormal (9). These studies implicate B cell subsets in the pathogenesis and/or maintenance of autoimmune diseases. Wolf and colleagues (10) have suggested a supplemental protective function of B cells against experimental autoimmune encephalomyelitis (EAE), a surrogate model of human multiple sclerosis, in B10.PL mice. The B cell–deficient B10.PL MT mice were unexpectedly unable to recover from EAE (Figure 1). Other mouse models have since confirmed that B cell depletion does not alleviate, but instead exaggerates, autoimmune traits. These findings have engendered, at least in the mouse, the concept of Breg cells, and evidence of their dominant role in immune regulation has been accumulating. Several mouse studies have allowed the dissection of mechanisms that underlie this B cell– induced regulation (for review, see ref. 11). That B cells are involved in some autoimmune conditions is not negated by such a new property. In this review, we critically describe some murine models of autoimmune rheumatic diseases and discuss some clues that suggest the existence of a human Christophe Jamin, PhD, Ahsen Morva, BSc, Sebastien Lemoine, BSc, Capucine Daridon, PhD, Pierre Youinou, MD, DSc, MACR: Brest University Medical School Hospital, Brest, France; Agnes Revol de Mendoza, PhD: Autonomous University of Nuevo Leon, Monterrey, Mexico. Dr. Youinou has received consulting fees, speaking fees, and/or honoraria (less than $10,000) from GlaxoSmithKline. Address correspondence and reprint requests to Pierre Youinou, MD, DSc, MACR, Laboratory of Immunology, Brest University Medical School Hospital, BP824, F29609 Brest, France. E-mail: youinou@univ-brest.fr. Submitted for publication December 19, 2007; accepted in revised form March 5, 2008.

Estrogen upregulates proinflammatory IFNγ via IL‐12, IL‐27, and STAT4β phosphorylation

Estrogen has been shown to be involved in many autoimmune diseases. Estrogen-modulated induction of IFNγ and IFNγ-inducible molecules are of key importance due to their potential role in autoimmunity. Therefore, we investigated IFNγ-inducing cytokines and related molecular pathways in splenocytes from estrogen-treated mice. A key IFNγ-inducing cytokine, IL-12p70, was increased in estrogen-treated mice compared to controls. Exposure of splenocytes from estrogen-treated mice to Con-A or rIL-12 induced selective phosphorylation of STAT4β with corresponding increase in expression of IFNγ, IFNγ-inducible nitric oxide, IL6, MCP1. This increase was followed by decreased expression of Th2 transcription factors (STAT6 and STAT5) in estrogen-treated mice. The modulation of IL-12-inducible molecules by estrogen could be due to a macrophage-derived Th1 early-inducing cytokine IL-27. Estrogen-treated mice had noticeably increased IL-27p28 in both from Con-A and LPS stimulated splenocytes and macrophages. rIL-27 also increased T-bet from estrogen samples. Splenocytes from estrogen-treated mice pretreated with IL-27 and then cultured with rIL-12 showed an increasing trend in IFNγ. These findings provide fresh insight into the potential role of estrogen in regulating IFNγ-inducing cytokines and may lead to novel therapeutic approaches in treating autoimmune diseases.

Expression, Genomic Structure and Mapping of the Thymus Specific Protease Prss16: A Candidate Gene for Insulin Dependent Diabetes Mellitus Susceptibility

PRSS16 is a serine protease specifically expressed by epithelial cells in the thymic cortex. The human gene is encoded on 6p21.3-p22 where recent linkage analysis has identified an association with insulin dependent diabetes mellitus (IDDM) susceptibility independent of HLA-DR3. To further investigate its potential role in autoimmunity, we characterized the mouse orthologue, Prss16. The genomic structure of Prss16 shows conservation with the human gene in size, number of exons and chromosomal location. Mapping of Prss16 places it on mouse chromosome 13 centromeric of thesatin locus. This region is comparable to the PRSS16 region on human chromosome 6 and has also been linked to quantitative trait locus for IDDM in the nonobese diabetic mouse. Similar to the human gene, Prss16 expression is highly specific in the mouse with expression limited to the cortical thymic epithelium. Notably, embryonic expression coincides with population of the thymic anlage with T-cell precursors and initiation of T-cell development. We also show that NOD and New Zealand Black mice, which have a disrupted thymic architecture and autoimmune phenotype, have lower levels of Prss16 expression compared to C57BL/6 mice. These findings support the role of Prss16 in T-cell development and susceptibility to autoimmunity in the mouse.

Evaluation of the Percentage of Peripheral T Cells with Two Different T Cell Receptor α-Chains and of their Potential Role in Autoimmunity

Approximately 25% of mature T cells possess two distinct cytoplasmic T cell receptor (TCR) α-chains, due to productive gene rearrangements of both alleles. Expression of two different α-chains at the cell surface is a potential risk factor for development of autoimmunity. However, it has been difficult to determine the frequency of peripheral T cells with two different α-chains at the surface. Our new approach is based on comparing by flow cytometry the percentage of cells that express a given Vα-chain between wild-type mice and mice that are hemizygous for a disrupted Tcra locus (Tcra+/−) and consequently unable to express two rearranged Tcra genes. We consistently found that ∼8% of total peripheral T cells express two surface α-chains. The importance of dual α-T cells in autoimmunity was examined in a mouse model for rheumatoid arthritis, namely collagen-induced arthritis (CIA). No significant difference was observed between Tcra+/− mice and wild-type littermates, considering arthritis incidence, day of disease onset, and maximum arthritic score. We therefore conclude that there is incomplete phenotypic allelic exclusion in TCRα, and that the presence of a significant number of potentially multireactive T cells does not increase the susceptibility to develop autoimmune arthritis.