Many autoimmune diseases (ADs) share similar underlying pathology and have a tendency to cluster within families, supporting the involvement of shared susceptibility genes. To date, most of the genetic variants associated with systemic lupus erythematosus (SLE) susceptibility also show association with others ADs. ITGAM and its associated ‘predisposing’ variant (rs1143679, Arg77His), predicted to alter the tertiary structures of the ligand-binding domain of ITGAM, may play a key role for SLE pathogenesis. The aim of this study is to examine whether the ITGAM variant is also associated with other ADs. We evaluated case-control association between rs1143679 and ADs (N=18,457) including primary Sjögren’s syndrome, systemic sclerosis, multiple sclerosis, rheumatoid arthritis, juvenile idiopathic arthritis, celiac disease, and type-1 diabetes. We also performed meta-analyses using our data in addition to available published data. Although the risk allele ‘A’ is relatively more frequent among cases for each disease, it was not significantly associated with any other ADs tested in this study. However, the meta-analysis for systemic sclerosis was associated with rs1143679 (pmeta=0.008). In summary, this study explored the role of ITGAM in general autoimmunity in seven non-lupus ADs, and only found association for systemic sclerosis when our results were combined with published results. Thus ITGAM may not be a general autoimmunity gene but this variant may be specifically associated with SLE and systemic sclerosis.
ITGAM; autoimmune diseases; genetic susceptibility
Recent advances in the field of genetics have dramatically changed our understanding of autoimmune disease. Candidate gene and, more recently, genome-wide association (GWA) studies have led to an explosion in the number of loci and pathways known to contribute to autoimmune phenotypes. Since the 1970s, researchers have known that several alleles in the MHC region play a role in the pathogenesis of many autoimmune diseases. More recent work has identified numerous risk loci involving both the innate and adaptive immune responses. However, much remains to be learned about the heritability of autoimmune conditions. Most regions found through GWA scans have yet to isolate the association to the causal allele(s) responsible for conferring disease risk. A role for rare variants (allele frequencies of <1%) has begun to emerge. Future research will use next generation sequencing (NGS) technology to comprehensively evaluate the human genome for risk variants. Whole transcriptome sequencing is now possible, which will provide much more detailed gene expression data. The dramatic drop in the cost and time required to sequence the entire human genome will ultimately make it possible for this technology to be used as a clinical diagnostic tool.
Genetics; Genomics; Genome-wide association study; Autoimmune disease
Vitiligo is an autoimmune disease presenting with progressive loss of skin pigmentation. The disease strikes 1% of the world population, generally during teenage years. The progressive loss of melanocytes from depigmenting vitiligo skin is accompanied by cellular infiltrates containing both CD4+ and CD8+ T lymphocytes. Infiltrating cytotoxic T cells with high affinity T cell receptors have likely escaped clonal deletion in the thymus, allowing such T cells to enter the circulation. Through the expression of CLA, these T cells home to the skin where they express type 1-cytokine profiles and mediate melanocyte apoptosis via the granzyme/perforin pathway. T cells found juxtapositionally apposed to remaining melanocytes can be isolated from the skin. Vitiligo T cells have demonstrated reactivity to antigens previously recognized as target antigens for T cells infiltrating melanoma tumors. In a comparison to existing melanoma-derived T cells, vitiligo T cells displayed superior reactivity towards melanoma cells. It is thought that genes encoding the TCRs expressed by vitiligo skin infiltrating T cells can be cloned and expressed in melanoma T cells, thereby generating a pool of circulating T cells with high affinity for their targets that can re-direct the immune response towards the tumor.
Melanocytes; T cells; T cell avidity; T cell receptors; Melanosomes; Antigen presentation
Consistent with the common embryonic origin of liver and pancreas as well the similar glucose-sensing systems in hepatocytes and pancreatic β-cells, it should not be surprising that liver stem cells/hepatocytes can transdifferentiate into insulin-producing cells under high-glucose culture conditions or by genetic reprogramming. Persistent expression of the pancreatic duodenal homeobox-1 (Pdx1) transcription factor or its super-active form Pdx1-VP16 fusion protein in hepatic cells reprograms these cells into pancreatic β-cell precursors. In vitro culture at elevated glucose concentrations or in vivo exposure to a hyperglycemia are required for further differentiation and maturation of liver-derived pancreatic β-cell precursor into functional insulin-producing pancreatic β-like cells. Under appropriate conditions, multiple pancreatic transcription factors can work in concert to reprogram liver stem/adult liver cells into functional insulin-producing cells. If such autologous liver-derived insulin-producing cells can be made to escape the type 1 diabetes-associated autoimmunity, they may serve as a valuable cell source for future cell replacement therapy without the need for life-long immunosuppression.
MicroRNAs are endogenous non-coding RNAs, approximately 22 nucleotides in length. They regulate gene expression and are important in a wide range of physiological and pathological processes. MicroRNA expression is tightly regulated during hematopoiesis and lymphoid cell differentiation and disruption of the entire microRNA network or selected microRNAs may lead to dysregulated immune responses. Abnormalities in microRNA expression related to inflammatory cytokines, Th-17 and regulatory T cells as well as B cells have been described in several autoimmune diseases. Sjögren’s syndrome is characterized by features of systemic autoimmunity and chronic inflammation and dysfunction in exocrine organs. Its clinical characteristics along with the relatively easy access to the target tissue and its product makes Sjögren’s syndrome appealing to study many aspects of microRNAs in a systemic autoimmune disease, such as their potential as diagnostic or prognostic biomarkers and their role in pathogenesis of autoimmunity, inflammation or organ dysfunction. Encouraging preliminary data from pilot studies in Sjögren’s syndrome demonstrate the potential of microRNAs as putative diagnostic and prognostic biomarker candidates which should be tested in larger more definite studies. Combining the comparison of microRNA expression profiles between various clinical subsets of Sjögren’s syndrome with bioinformatic modeling tools may predict formerly unsuspected pathways which may contribute to the disease process and lead to the generation of testable novel hypothesis of pathogenesis.
biomarker; autoimmunity; epigenetics; exocrine dysfunction; pathogenesis
The pathogenesis of RA, a disabling autoimmune disease, is incompletely understood. Early in the development of RA there appears to be loss of immune homeostasis and regulation, and premature immunosenescence. While identification of risk factors and understanding of the phases of RA pathogenesis are advancing, means of accurately predicting an individual’s risk of developing RA are currently lacking. Telomere length has been proposed as a potential new biomarker for the development of RA that could enhance prediction of this serious disease. Studies examining telomere length in relation to RA have found that telomere erosion appears to proceed more rapidly in subjects with RA than in healthy controls, and that telomere lengths are shorter in those with the RA-risk HLA-shared epitope genes. These studies have been small, however, with retrospective or cross-sectional designs. The potential role of telomere shortening as an independent biomarker for future RA risk, perhaps strongly genetically determined by HLA-SE genes, after controlling for known risk factors such as smoking, body mass index and immunosuppressant medication use, as well as systemic inflammation, is an unanswered question.
immunosenescence; rheumatoid arthritis; telomere; biomarker; risk factor; aging; autoimmune
Pituitary autoimmunity encompasses a spectrum of conditions ranging from histologically proven forms of lymphocytic hypophysitis to the presence of pituitary antibodies in apparently healthy subjects. Hypophysitis is a rare but increasingly recognized disorder that typically presents as a mass in the sella turcica. It mimics clinically and radiologically other non-secreting sellar masses, such as the more common pituitary adenoma. Hypophysitis shows a striking temporal association with pregnancy, and it has been recently described during immunotherapies that block CTLA-4. Several candidate pituitary autoantigens have been described in the last decade, although none has proven useful as a diagnostic tool. This review summarizes the advances made in the field since the publication of the first review on pituitary autoimmunity, and the challenges that await clarification.
Hypophysitis; Pituitary antigens; Pituitary antibodies
Recent evidence supports the idea that following a break in tolerance, CD8 cytotoxic T lymphocytes (CTL) may be an important but unrecognized mechanism for limiting expansion of autoreactive B cells. Failure of this mechanism could allow persistence of CD4 T cell driven polyclonal B cell activation resulting in clinical lupus. Although CD8 CTL failure may occur early in disease, work in mice supports the concept that therapeutic CTL enhancement may be both practical and beneficial in lupus. Devising such therapy for humans will first require an understanding of the in vivo mechanisms critical in CTL expansion and down regulation, particularly in the lupus setting which may differ from CTL generation in other clinical settings (e.g. tumors, infections).
Lupus; Cytotoxic T cells; Graft-vs-host disease
The loss of immune tolerance to self antigens leads to the development of autoimmune responses. Since self antigens are often multiple and/or their sequences may not be known, one approach to restore immune tolerance uses synthetic artificial peptides that interfere or compete with self peptides in the networks of cellular interactions that drive the autoimmune process. This review describes the rationale behind the use of artificial peptides in autoimmunity and their mechanisms of action. Examples of use of artificial peptides in preclinical studies and in the management of human autoimmune diseases are provided.
Artificial peptides; Immune tolerance; Multiple Sclerosis; Systemic Lupus Erythematosus; Glatiramer Acetate
Systemic lupus erythematosus (SLE) is prototypic autoimmune disease characterized by the production of autoantibodies to DNA among other nuclear molecules. These antibodies can form immune complexes that promote pathogenesis by stimulating cytokine production and depositing in the kidney to instigate nephritis. The antigens that form these complexes arise from the blood nucleome, a pool of circulating macromolecules comprised of DNA, RNA and nuclear proteins released from cells. Cell death is a major source of these molecules, releasing DNA in a process that can be modeled in mice by the administration of cells killed ex vivo. In the mouse model, the appearance of blood DNA requires macrophages and differs between males and females. This finding raises the possibility that augmented levels of extracellular DNA and other nuclear antigens can contribute to the increased frequency of SLE in females. Extracellular DNA can occur in both a soluble and particulate form, with microparticles generated in vitro displaying antigenically active DNA. Together, these findings suggest that cell death is an important event in lupus pathogenesis and can provide a supply of blood DNA essential for immune complex formation.
systemic lupus erythematosus; immune complexes; DNA; nucleome; apoptosis; macrophages
Autoimmunity is controlled both by the environment and by genetic factors. One of the most well defined genetic factors is polymorphisms, with some alleles of particular genes promoting autoimmune diseases, whereas other alleles either not affecting susceptibility to disease or, in some cases actually inhibiting the appearance of such illnesses. Another genetically controlled factor, gender, also plays a profound role in the incidence of autoimmune diseases. For example, Systemic Lupus Erythematosus (SLE) occurs much more frequently in females than in males in both mice and man. The genetic differences that make some individuals susceptible to autoimmunity and protect others could act in many ways and affect many tissues. In this review we will discuss how gender may act on the cells of the immune system and thereby influence the predisposition of the host to autoimmune diseases.
autoimmunity; sex hormones; X chromosome; TLR7
Cancer sera contain antibodies that react with a unique group of autologous cellular antigens called tumor-associated antigens (TAAs), and therefore these autoantibodies can be considered as reporters from the immune system, to identify authentic TAAs involved in the malignant transformation. Once a TAA is identified, different approaches would be used to comprehensively characterize and validate the identified TAA/anti-TAA systems that are potential biomarkers in cancer immunodiagnosis. In this manner, several novel TAAs such as p62 and p90 have been identified in our previous studies. p62, a member of IGF-II mRNA binding proteins (IMPs), is an oncofetal protein absent in adult tissues, the presence of anti-p62 autoantibodies relates to abnormal expression of p62 in tumor cells. p90 was recently characterized as an inhibitor of the tumor suppressor PP2A (protein phosphatase 2A), and an autoantibody to p90 appears in high frequency in prostate cancer. The present review will focus on the recent advances in studies mainly associated with these two novel TAAs as biomarkers in cancer immunodiagnosis.
Autoantibody; Tumor-associated antigen; p62/IMP2; p90/CIP2A; Immunodiagnosis; Cancer
While CD4+CD25high regulatory T cells (Tregs) have garnered much attention for their role in the maintenance of immune homeostasis, recent findings have shown that subsets of CD8+ T cells (CD8+ Tregs) display immunoregulatory functions as well. Both CD4+ Tregs and CD8+ Tregs appear impaired in number and/or function in several autoimmune diseases and in experimental animal models of autoimmunity, suggesting the possibility of immunotherapeutic targeting of these cells for improved management of autoimmune conditions. Our group has developed a strategy to induce CD8+ Tregs in autoimmune mice through the use of a tolerogenic self-peptide, and new information has been gained on the phenotype, function and role of induced CD8+ Tregs in autoimmunity. Here we present an overview of the role and mechanisms of action of CD8+ Tregs in autoimmunity, with a special focus on lupus. We also discuss the potential role of CD8+ Tregs in other diseases, including chronic infection and cancer.
Autoimmunity; Systemic Lupus Erythematosus; CD8+Tregs; Immune tolerance/ Suppression
Programmed death 1 (PD-1) and its ligands (PD-L1 and PD-L2) are responsible for inhibitory T cell signaling that helps mediate the mechanisms of tolerance and immune homeostasis. The PD-1:PD-L signaling pathway has been shown to play an important role in a variety of diseases, including autoimmune conditions, chronic infection, and cancer. Recently, investigators have explored the role of sex hormones in modulating the pathway in autoimmune conditions. Exploring the effects of sex hormones on the PD-1:PD-L pathway could shed light on the gender biased nature of many autoimmune conditions as well as aide in the development of therapeutics targeting the immune system.
PD-1; Gender; Sex hormones; Autoimmunity; Systemic lupus erythematosus; Immune system
Systemic lupus erythematosus (SLE) is a complex autoimmune disorder marked by an inappropriate immune response to nuclear antigens. Recent whole genome association and more focused studies have revealed numerous genes implicated in this disease process, including ITGAM, Fc gamma receptors, complement components, C-reactive protein, and others. One common feature of these molecules is their involvement in the immune opsonins pathway and phagocytic clearing of nuclear antigens and apoptotic debris which provide excessive exposure of lupus-related antigens to immune cells. Analysis of gene-gene interactions in the opsonin pathway and its relationship to SLE may provide a systems-based approach to identify additional candidate genes associated with disease able to account for a larger part of lupus susceptibility.
SLE; opsonin; pathway; genetic association
Autoimmune diseases comprise a group of about 85 heterogeneous conditions that can affect virtually any organ and tissue in the body. Many autoimmune diseases change significantly during pregnancy: some ameliorate, some worsen, and others are unaffected. Two autoimmune diseases present prominently in relation to pregnancy: postpartum autoimmune thyroiditis and autoimmune hypophysitis. This article will review the current state of knowledge of the immunological changes that occur during normal pregnancy, and will explore the striking temporal association with pregnancy observed in thyroiditis and hypophysitis.
Pregnancy; Hypophysitis; Postpartum thyroiditis
Improving cancer immunotherapy by targeting T cell network also triggers autoimmunity. We disrupted regulatory T cell (Treg) function to probe the balance between breast cancer vaccination and autoimmune thyroiditis (EAT) in four models, with particular attention to MHC-associated susceptibility, EAT induction with mouse thyroglobulin (mTg) without adjuvant, and tolerance to Her-2/neu in transgenic mice. 1) In EAT-resistant BALB/c mice, Treg depletion enhanced tumor regression, and facilitated mild thyroiditis induction. 2) In Her-2 tolerant C57BL/6 mice expressing HLA-DR3, an EAT-susceptibility allele, Her-2 DNA vaccinations must follow Treg depletion for (Her-2xDR3)F1 mice to resist tumor challenge; thyroiditis incidence was moderated by the EAT-resistant IAb allele. 3) In neu tolerant, EAT-resistant BALB/c mice, implanted neu+ tumor also regressed only after Treg depletion and DNA vaccinations. Tumor immunity was long-term, providing protection from spontaneous tumorigenesis. In all three, immune stimuli from concurrent tumor regression and EAT development have a noticeable, mutually augmenting effect. 4) In Treg-depleted, EAT-susceptible CBA/J mice, strong tumor protection was established by immunization with a cell vaccine. mTg injections led to greater thyroiditis incidence and severity. Combination models with MHC class II diversity should facilitate autoimmunity risk assessment and management while generating tumor immunity.
Immunotherapy and autoimmunity; Autoimmunity risk; Regulatory T cell; Her-2/neu tolerance; Thyroiditis indicator; Autoimmune sequelae
It is well known that ultraviolet radiation can exacerbate skin disease in patients with lupus erythematosus. While many patients are advised to avoid sunlight and artificial tanning, it is not clear how best to counsel patients regarding the use of indoor lamps. Indeed, many of the light bulbs commonly used in the home and workplace emit low-dose ultraviolet radiation. The irradiance is considerably lower than that of the sun, however the exposure time can last for hours and is typically repeated on a daily basis. Therefore, it is possible that this chronic exposure could ultimately result in a significant accumulation of damage.
Lupus erythematosus; ultraviolet radiation; halogen; incandescent; fluorescent
Paraneoplastic retinopathies (PR), including cancer-associated retinopathy (CAR) or the closely related melanoma-associated retinopathy (MAR) occur in a small subset of patients with retinal degeneration and systemic cancer. This autoimmune syndrome is characterized by sudden, progressive loss of vision in association with circulating anti-retinal autoantibodies. The PR syndromes are heterogeneous, may produce a number of ocular symptoms, and may be associated with several different neoplasms, including lung, breast, prostate, gynecological, and colon cancer, melanoma, and hematologic malignancies. We examined the onset of retinopathy in correlation to the diagnosis of cancer and the presence of specific anti-retinal autoantibodies in PR patients. In some patients without diagnosed malignant tumors, the onset of ocular symptoms and the presence of autoantibodies preceded the diagnosis of cancer by months to years, including anti-recoverin, anti-transducin-α, and anti-carbonic anhydrase II antibodies. Although anti-retinal autoantibodies may not be a good predictor of a specific neoplasm, they can be used as biomarkers for different subtypes of retinopathy. Identification of autoantibodies involved in autoimmune-mediated PR will help elucidate the mechanisms underlying the PR syndromes and develop targeted therapies for these sight-threatening disorders.
Cancer-associated retinopathy; anti-retinal autoantibodies; recoverin; enolase; autoimmune retinopathy
Heat-shock proteins (Hsps) are among the most highly conserved and immunogenic proteins shared by microbial agents and mammals. Under physiological conditions, the ubiquitously distributed Hsps maintain the integrity and function of other cellular proteins when cells are exposed to stressful stimuli. However, owing to their conserved nature and stress inducibility, Hsps may become targets of immune response. The T cells and/or antibodies induced by a microbial Hsp may crossreact with the corresponding mammalian Hsp (molecular mimicry) and trigger an autoimmune response, which if unchecked can lead to immune pathology and clinical manifestations. Furthermore, enhanced expression of Hsp under stress can unveil previously hidden antigenic determinants that can initiate and perpetuate autoimmune reactivity. Also, the innate immune mechanisms activated by an Hsp can reinforce and even direct the type of adaptive immune response to that protein. Hsps have been implicated in the induction and propagation of autoimmunity in several diseases, including rheumatoid arthritis, atherosclerosis and type 1 diabetes. However, Hsps possess immunoregulatory attributes as well and therefore, are being exploited for immunomodulation of various immune-mediated disorders.
Autoimmunity; Heat-shock proteins; Immunomodulation; Inflammation; Molecular mimicry; Stress proteins
Serologic association, cross-reactivity of select EBV-specific antibodies with SLE autoantigens, SLE-like autoimmunity after immunization with EBV peptides, increased EB viral load in SLE patients, and SLE-specific alterations in EBV humoral and cellular immunity implicate Epstein–Barr virus (EBV) in the development of systemic lupus erythematosus (SLE). To investigate SLE-specific differences in EBV gene expression, levels of eight EBV genes were compared between SLE patients and controls by using both ex vivo-infected and un-manipulated peripheral blood mononuclear cells (PBMCs). Expression levels of mRNA were significantly greater by Wilcoxen signed rank test in the ex vivo-infected SLE patient-derived cells for 4 of 8 EBV genes, including BLLF1, 3.2-fold (p<0.004); LMP-2, 1.7-fold (p<0.008); EBNA-1, 1.7-fold (p<0.01); and BcRF1, a proposed DNA binding protein, 1.7-fold (p<0.02). The frequency of LMP-1 gene expression was significantly greater by Chi square analysis in the peripheral blood from SLE patients than controls (44% of patients, 10% of controls p<0.05). PBMCs from SLE patients had greater expression of latent genes as well as increased expression of both latent and lytic genes after infection, suggesting that EBV may participate in SLE etiology through several mechanisms. Such altered infection patterns may contribute to the increased levels of EBV and the molecular mimicry seen in sera from SLE patients.
Systemic lupus erythematosus; Epstein–Barr virus; Gene expression; Latency
Regulation of B cell receptor signaling is essential for the development of specific immunity while retaining tolerance to self. Systemic lupus erythematosus (SLE) is characterized by a loss of B cell tolerance and the production of anti-self antibodies. Accompanying this break down in tolerance are alterations in B cell receptor signal transduction including elevated induced calcium responses and increased protein phosphorylation. Specific pathways that negatively regulate B cell signaling have been shown to be impaired in some SLE patients. These patients have reduced levels of the kinase Lyn in lipid raft microdomains and this reduction is inversely correlated with increased CD45 in lipid rafts. Function and expression of the inhibitory immunoglobulin receptor FcγRIIB is also reduced in Lupus IgM- CD27+ memory cells. Because the relative contribution of different memory and transitional B cell subsets can be abnormal in SLE patients, we believe studies targeted to well defined B cell subsets will be necessary to further our understanding of signaling abnormalities in SLE. Intracellular flow cytometric analysis of signaling is a useful approach to accomplish this goal.
B cells; Systemic Lupus Erythematosus; Signal Transduction; Human
Systemic lupus erythematosus (SLE) is characterized by abnormal T-cell activation and death, processes which are crucially dependent on the controlled production of reactive oxygen intermediates (ROI) and of ATP in mitochondria. The mitochondrial transmembrane potential (Δψm) has conclusively emerged as a critical checkpoint of ATP synthesis and cell death. Lupus T cells exhibit persistent elevation of Δψm or mitochondrial hyperpolarization (MHP) as well as depletion of ATP and glutathione which decrease activation-induced apoptosis and instead predispose T cells for necrosis, thus stimulating inflammation in SLE. NO-induced mitochondrial biogenesis in normal T cells accelerates the rapid phase and reduces the plateau of Ca2+ influx upon CD3/CD28 co-stimulation, thus mimicking the Ca2+ signaling profile of lupus T cells. Treatment of SLE patients with rapamycin improves disease activity, normalizes CD3/CD28-induced Ca2+ fluxing but fails to affect MHP, suggesting that altered Ca2+ fluxing is downstream or independent of mitochondrial dysfunction. Understanding the molecular basis and consequences of MHP is essential for controlling T-cell activation and death signaling in SLE.
Lupus T cells exhibit mitochondrial dysfunctionMitochondrial hyperpolarization (MHP) and ATP depletion predispose lupus T cells to death by necrosis which is pro-inflammatoryMHP is caused by depletion of glutathione and exposure to nitric oxide (NO)NO-induced mitochondrial biogenesis regenerates the Ca2+ signaling profile of lupus T cellsRapamycin treatment normalizes Ca2+ fluxing but not MHP, suggesting that the mammalian target of rapamycin, acts as a sensor and effector of MHP in SLE
lupus; mitochondria; nitric oxide; glutathione; calcium
The regulation of IL-2 production is central to our understanding of the immune system. Key during T cell activation, it also plays an essential role in the regulation of the immune response. This review discusses the function of recently described factors that modulate transcription and chromatin remodeling at the IL2 promoter. Also, it addresses the role of FoxP3 as a transcriptional regulator in conventional T cells and regulatory T cells, and the mechanisms whereby CD28 stabilizes IL2 transcription and translation. Finally, the alterations that prevent T cells from SLE patients from producing normal amounts of IL-2 upon stimulation are described.
Chromatin remodeling; FoxP3; IL-2; Systemic Lupus Erythematosus; Transcriptional regulation