Association of genetic variations in the STAT4 and IRF7/KIAA1542 regions with systemic lupus erythematosus in a Northern Han Chinese population

Insight into the role of IRF7 in skin and connective tissue diseases

Interferons (IFNs) are signalling proteins primarily involved in initiating innate immune responses against pathogens and promoting the maturation of immune cells. Interferon Regulatory Factor 7 (IRF7) plays a pivotal role in the IFNs signalling pathway. The activation process of IRF7 is incited by exogenous or abnormal nucleic acids, which is followed by the identification via pattern recognition receptors (PRRs) and the ensuing signalling cascades. Upon activation, IRF7 modulates the expression of both IFNs and inflammatory gene regulation. As a multifunctional transcription factor, IRF7 is mainly expressed in immune cells, yet its presence is also detected in keratinocytes, fibroblasts, and various dermal cell types. In these cells, IRF7 is critical for skin immunity, inflammation, and fibrosis. IRF7 dysregulation may lead to autoimmune and inflammatory skin conditions, including systemic scleroderma (SSc), systemic lupus erythematosus (SLE), Atopic dermatitis (AD) and Psoriasis. This comprehensive review aims to extensively elucidate the role of IRF7 and its signalling pathways in immune cells and keratinocytes, highlighting its significance in skin-related and connective tissue diseases.

IRF7: role and regulation in immunity and autoimmunity

Interferon regulatory factor (IRF) 7 was originally identified as master transcriptional factor that produced IFN-I and regulated innate immune response, subsequent studies have revealed that IRF7 performs a multifaceted and versatile functions in multiple biological processes. In this review, we provide a comprehensive overview on the current knowledge of the role of IRF7 in immunity and autoimmunity. We focus on the latest regulatory mechanisms of IRF7 in IFN-I, including signaling pathways, transcription, translation, and post-translational levels, the dimerization and nuclear translocation, and the role of IRF7 in IFN-III and COVID-19. In addition to antiviral immunity, we also discuss the role and mechanism of IRF7 in autoimmunity, and the further research will expand our understanding of IRF7.

Polymorphism in STAT4 Increase the Risk of Systemic Lupus Erythematosus: An Updated Meta-Analysis

Previous studies have reported that STAT4 rs7574865 conferred the susceptibility to systemic lupus erythematosus (SLE). In this study, a meta-analysis (including 32 comparative studies of 11384 patients and 17609 controls) was conducted to investigate the role of STAT4 polymorphism in SLE in a comprehensive way. We found that the Asian population had the highest prevalence of the T allele than any other study population at 32.2% and that STAT4 rs7574865 polymorphism was associated with SLE in the overall population (OR = 1.579, 95%CI = 1.497-1.665, P < 0.001). In the subgroup analysis by ethnicity, STAT4 rs7574865 T allele was shown to be risk factor in SLE in Asian, European, and American origins. Our results do support STAT4 rs7574865 polymorphism as a susceptibility factor for SLE in populations of different ethnic and that its prevalence is ethnicity dependent.

Association of signal transducer and activator of transcription 4 gene (restriction site7582694) single nucleotide polymorphism with systemic lupus erythematosus

Background — Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease characterized by production of autoantibodies and deposition within various organs. The incidence of SLE averages 5 cases per 100,000 population. Various genome wide studies have shown association of STAT4 (signal transducer and activator of transcription 4) gene with SLE and lupus nephritis (LN). Therefore, this study was designed to determine single nucleotide polymorphism (SNP) in STAT4 (rs7582694) in local SLE, LN patients and healthy controls. Objective — To determine the frequency of STAT4 (rs7582694) gene polymorphism in systemic lupus erythematosus, lupus nephritis patients and healthy controls. Methods — It was a case-control study. Eighty samples were recruited for each of two study groups. Deoxyribonucleic acid (DNA) extraction was carried out using standard phenol chloroform method. Further, samples were processed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) conventional technique and genotypes were determined. Polymorphism analysis and allele frequencies were compared between groups using the chi-square test. Project was approved by the Ethical Review Board at the University of Health Sciences, Lahore, Pakistan. Results — Females were more inclined towards developing SLE. The study unveiled that SNP in STAT 4 gene (rs7582694) was associated with SLE patients in Pakistani population which indicates that this may play a role in susceptibility to SLE. Moreover, we infer that genetic variations within STAT4 (rs7582694) predispose patients to lupus nephritis. It was also evident that GG and GC genotypes were more susceptible of further transforming into SLE and LN. Conclusion: The findings of this study may contribute to a better understanding of underlying etiological and prognostic factors regarding SLE and LN.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.

IRF7 Gene Variations Confer Susceptibility to Autoimmune Thyroid Diseases and Graves' Ophthalmopathy

The objective of this study was to investigate whether IRF7 polymorphisms are associated with autoimmune thyroid diseases (AITDs). We selected three single nucleotide polymorphisms (SNPs) of IRF7, namely, rs1061501, rs1131665, and rs1061502 for genotyping using PCR-based ligase detection reaction (LDR) method in a total of 1659 participants (592 with Graves' disease, 297 with Hashimoto's thyroiditis, and 770 healthy controls). Gene-disease and genotype-clinical phenotype associations were evaluated for the three SNPs. Our results showed that the AG genotype and the minor allele G frequency of rs1131665 and rs1061502 in AITD patients were both higher than those of the controls (rs1131665: AG genotype: P = 0.017, OR = 1.968; allele G: P = 0.018, OR = 1.946; rs1061502: AG genotype: P = 0.029, OR = 1.866; allele G: P = 0.031, OR = 1.847). Subgroup analysis also showed that the AG genotype and the minor allele G frequency of rs1131665 and rs1061502 in Graves' disease patients were both higher than those of the controls (rs1131665: AG genotype: P = 0.015, OR = 2.074; allele G: P = 0.016, OR = 2.048; rs1061502: AG genotype: P = 0.034, OR = 1.919; allele G: P = 0.035, OR = 1.898). Furthermore, the allele G frequency of rs1061501 was associated with Graves' ophthalmopathy (P = 0.035, OR = 1.396). No significant difference in IRF7 polymorphisms was found between Hashimoto's thyroiditis patients and controls. Our study has revealed for the first time that IRF7 is a susceptibility gene for AITD, especially for Graves' disease and Graves' ophthalmopathy.

Sexual dimorphism in SLE: above and beyond sex hormones

Systemic lupus erythematosus (SLE) is characterized by aberrant production of auto-antibodies and a sexual dimorphism both in the phenotypic expression and frequency of the disease between males and females. The striking female predominance was initially attributed primarily to sex hormones. However, recent data challenge this simplistic view and point more towards genetic and epigenetic factors accounting for this difference. More specifically, several SLE-associated single-nucleotide polymorphisms (SNPs) have been found to play an important role in the gender predilection in SLE. Their effect is mediated through their involvement in sex-hormone and immune system signalling and dysregulation of the expression of genes and miRNAs pertinent to the immune system. Additionally, the genetic factors are interchangeably associated with epigenetic modifications such as DNA methylation and histone modification, thus revealing a highly complex network of responsible mechanisms. Of importance, disturbance in the epigenetic process of X chromosome inactivation in females as well as in rare X chromosome abnormalities leads to increased expression of X-linked immune-related genes and miRNAs, which might predispose females to SLE. Microbiota dysbiosis has also been implicated in the sexual dimorphism by the production of oestrogens within the gut and the regulation of oestrogen-responsive immune-related genes. Sexual dimorphism in SLE is an area of active research, and elucidation of its molecular basis may facilitate ongoing efforts towards personalized care.

A plausibly causal functional lupus-associated risk variant in the STAT1-STAT4 locus

Systemic lupus erythematosus (SLE or lupus) (OMIM: 152700) is a chronic autoimmune disease with debilitating inflammation that affects multiple organ systems. The STAT1-STAT4 locus is one of the first and most highly replicated genetic loci associated with lupus risk. We performed a fine-mapping study to identify plausible causal variants within the STAT1-STAT4 locus associated with increased lupus disease risk. Using complementary frequentist and Bayesian approaches in trans-ancestral Discovery and Replication cohorts, we found one variant whose association with lupus risk is supported across ancestries in both the Discovery and Replication cohorts: rs11889341. In B cell lines from patients with lupus and healthy controls, the lupus risk allele of rs11889341 was associated with increased STAT1 expression. We demonstrated that the transcription factor HMGA1, a member of the HMG transcription factor family with an AT-hook DNA-binding domain, has enriched binding to the risk allele compared with the non-risk allele of rs11889341. We identified a genotype-dependent repressive element in the DNA within the intron of STAT4 surrounding rs11889341. Consistent with expression quantitative trait locus (eQTL) analysis, the lupus risk allele of rs11889341 decreased the activity of this putative repressor. Altogether, we present a plausible molecular mechanism for increased lupus risk at the STAT1-STAT4 locus in which the risk allele of rs11889341, the most probable causal variant, leads to elevated STAT1 expression in B cells due to decreased repressor activity mediated by increased binding of HMGA1.

The innate immune system in human systemic lupus erythematosus

Although the role of adaptive immune mechanisms, e.g. autoantibody formation and abnormal T-cell activation, has been long noted in the pathogenesis of human systemic lupus erythematosus (SLE), the role of innate immunity has been less well characterized. An intricate interplay between both innate and adaptive immune elements exists in protective anti-infective immunity as well as in detrimental autoimmunity. More recently, it has become clear that the innate immune system in this regard not only starts inflammation cascades in SLE leading to disease flares, but also continues to fuel adaptive immune responses throughout the course of the disease. This is why targeting the innate immune system offers an additional means of treating SLE. First trials assessing the efficacy of anti-type I interferon (IFN) therapy or modulators of pattern recognition receptor (PRR) signalling have been attempted. In this review, we summarize the available evidence on the role of several distinct innate immune elements, especially neutrophils and dendritic cells as well as the IFN system, as well as specific innate PRRs along with their signalling pathways. Finally, we highlight recent clinical trials in SLE addressing one or more of the aforementioned components of the innate immune system.

Molecular and Immunological Basis of Tubulo-Interstitial Injury in Lupus Nephritis: a Comprehensive Review

Lupus nephritis is an important cause of kidney failure in patients of Asian, African, or Hispanic descent. Its etiology and pathogenesis are multifactorial and remain to be elucidated. Accumulating evidence suggests that anti-double-stranded DNA (dsDNA) antibodies play a critical role in the pathogenesis, through its direct binding to cross-reactive antigens on resident renal cells or indirect binding through chromatin material to extracellular matrix components, resulting in complement activation, cell activation and proliferation, and induction of inflammatory and fibrotic processes. While tubulo-interstitial damage portends poor long-term renal prognosis, the mechanisms leading to tubulo-interstitial injury in lupus nephritis has received relatively less attention to date. Immune deposition along the tubular basement membrane is often observed in lupus nephritis and correlates with tubulo-interstitial infiltration of immune cells and interstitial fibrosis. Anti-dsDNA antibodies bind to resident renal cells, including proximal renal tubular epithelial cells, and contribute to renal inflammation and fibrosis. There is emerging evidence that epigenetic influence such as DNA methylation, histone modification, and microRNAs (miRs) also contribute to kidney fibrosis. Overexpression of miR-150 is observed in renal biopsies from patients with lupus nephritis and correlates with kidney fibrosis and chronicity score. Mycophenolate mofetil (MMF) is an established and effective standard-of-care therapy for patients with lupus nephritis. Accumulating data suggest that in addition to its immunosuppressive actions on lymphocyte proliferation, mycophenolic acid (MPA), the active metabolite of MMF, can exert a direct effect on nonimmune cells. Mediators of inflammation and fibrosis induced by anti-dsDNA antibodies in cultured proximal renal tubular epithelial cells are ameliorated by the addition of MPA, suggesting that in addition to its immunosuppressive actions, MPA may also have a beneficial effect in improving tubulo-interstitial inflammation and fibrosis through its direct action on proximal renal tubular epithelial cells.

Genetics of Lupus Nephritis: Clinical Implications

Systemic lupus erythematosus is a heterogeneous autoimmune disease marked by the presence of pathogenic autoantibodies, immune dysregulation, and chronic inflammation that may lead to increased morbidity and early mortality from end-organ damage. More than half of all systemic lupus erythematosus patients will develop lupus nephritis. Genetic-association studies have identified more than 50 polymorphisms that contribute to lupus nephritis pathogenesis, including genetic variants associated with altered programmed cell death and defective immune clearance of programmed cell death debris. These variants may support the generation of autoantibody-containing immune complexes that contribute to lupus nephritis. Genetic variants associated with lupus nephritis also affect the initial phase of innate immunity and the amplifying, adaptive phase of the immune response. Finally, genetic variants associated with the kidney-specific effector response may influence end-organ damage and the progression to end-stage renal disease and death. This review discusses genetic insights of key pathogenic processes and pathways that may lead to lupus nephritis, as well as the clinical implications of these findings as they apply to recent advances in biologic therapies.

Genetic Factors in Systemic Lupus Erythematosus: Contribution to Disease Phenotype

Genetic factors exert an important role in determining Systemic Lupus Erythematosus (SLE) susceptibility, interplaying with environmental factors. Several genetic studies in various SLE populations have identified numerous susceptibility loci. From a clinical point of view, SLE is characterized by a great heterogeneity in terms of clinical and laboratory manifestations. As widely demonstrated, specific laboratory features are associated with clinical disease subset, with different severity degree. Similarly, in the last years, an association between specific phenotypes and genetic variants has been identified, allowing the possibility to elucidate different mechanisms and pathways accountable for disease manifestations. However, except for Lupus Nephritis (LN), no studies have been designed to identify the genetic variants associated with the development of different phenotypes. In this review, we will report data currently known about this specific association.

Association of STAT4 rs7574865 with susceptibility to systemic lupus erythematosus in Iranian population

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease with complex genetic inheritance that affecting different organs and systems. STAT4 has been newly identified as a susceptible gene in the development of SLE. According to recent studies, STAT4 has been associated with SLE in various populations. We investigated whether STAT4 single nucleotide polymorphisms (SNPs) were associated with susceptibility and clinical features of SLE in Iranian patients. The study group comprised 280 patients with SLE and 281 sex-, age-, and ethnicity-matched healthy controls of Iranian ancestry. Two SNPs (rs7574865 and rs7601754) were genotyped using the TaqMan MGB Allelic Discrimination method. Our results showed a significant association between rs7574865 T allele (odds ratio (OR) = 1.50, 95 % CI = 1.18-1.92, P = 0.002) and susceptibility to SLE. The rs7574865TT genotype (P = 0.02, OR = 1.94, 95 % CI = 1.74-3.19) and GT genotype (P = 0.008, OR = 1.71, 95 % CI = 1.19-2.45) showed a significant association with the risk of SLE in the Iranian population. We concluded that STAT4 rs7574865 is associated with SLE susceptibility in the Iranian population and this SNP might be a factor in the pathogenesis of SLE. However, further studies are required to investigate the mechanism by which polymorphisms in this gene lead to SLE.

Systemic lupus erythematosus diagnostics in the 'omics' era

Systemic lupus erythematosus is a complex autoimmune disease affecting multiple organ systems. Currently, diagnosis relies upon meeting at least four out of eleven criteria outlined by the ACR. The scientific community actively pursues discovery of novel diagnostics in the hope of better identifying susceptible individuals in early stages of disease. Comprehensive studies have been conducted at multiple biological levels including: DNA (or genomics), mRNA (or transcriptomics), protein (or proteomics) and metabolites (or metabolomics). The 'omics' platforms allow us to re-examine systemic lupus erythematosus at a greater degree of molecular resolution. More importantly, one is hopeful that these 'omics' platforms may yield newer biomarkers for systemic lupus erythematosus that can help clinicians track the disease course with greater sensitivity and specificity.

Genetics of SLE: functional relevance for monocytes/macrophages in disease

Genetic studies in the last 5 years have greatly facilitated our understanding of how the dysregulation of diverse components of the innate immune system contributes to pathophysiology of SLE. A role for macrophages in the pathogenesis of SLE was first proposed as early as the 1980s following the discovery that SLE macrophages were defective in their ability to clear apoptotic cell debris, thus prolonging exposure of potential autoantigens to the adaptive immune response. More recently, there is an emerging appreciation of the contribution both monocytes and macrophages play in orchestrating immune responses with perturbations in their activation or regulation leading to immune dysregulation. This paper will focus on understanding the relevance of genes identified as being associated with innate immune function of monocytes and macrophages and development of SLE, particularly with respect to their role in (1) immune complex (IC) recognition and clearance, (2) nucleic acid recognition via toll-like receptors (TLRs) and downstream signalling, and (3) interferon signalling. Particular attention will be paid to the functional consequences these genetic associations have for disease susceptibility or pathogenesis.

Lupus nephritis: a critical review

Lupus nephritis remains one of the most severe manifestations of systemic lupus erythematosus associated with considerable morbidity and mortality. A better understanding of the pathogenesis of lupus nephritis is an important step in identifying more targeted and less toxic therapeutic approaches. Substantial research has helped define the pathogenetic mechanisms of renal manifestations and, in particular, the complex role of type I interferons is increasingly recognized; new insights have been gained into the contribution of immune complexes containing endogenous RNA and DNA in triggering the production of type I interferons by dendritic cells via activation of endosomal toll-like receptors. At the same time, there have been considerable advances in the treatment of lupus nephritis. Corticosteroids have long been the cornerstone of therapy, and the addition of cyclophosphamide has contributed to renal function preservation in patients with severe proliferative glomerulonephritis, though at the cost of serious adverse events. More recently, in an effort to minimize drug toxicity and achieve equal effectiveness, other immunosuppressive agents, including mycophenolate mofetil, have been introduced. Herein, we provide a detailed review of the trials that established the equivalency of these agents in the induction and/or maintenance therapy of lupus nephritis, culminating in the recent publication of new treatment guidelines by the American College of Rheumatology. Although newer biologics have been approved and continue to be a focus of research, they have, for the most part, been relatively disappointing compared to the effectiveness of biologics in other autoimmune diseases. Early diagnosis and treatment are essential for renal preservation.

Contribution of STAT4 gene single-nucleotide polymorphism to systemic lupus erythematosus in the Polish population

The STAT4 has been found to be a susceptible gene in the development of systemic lupus erythematosus (SLE) in various populations. There are evident population differences in the context of clinical manifestations of SLE, therefore we investigated the prevalence of the STAT4 G > C (rs7582694) polymorphism in patients with SLE (n = 253) and controls (n = 521) in a sample of the Polish population. We found that patients with the STAT4 C/G and CC genotypes exhibited a 1.583-fold increased risk of SLE incidence (95 % CI = 1.168–2.145, p = 0.003), with OR for the C/C versus C/G and G/G genotypes was 1.967 (95 % CI = 1.152–3.358, p = 0.0119). The OR for the STAT4 C allele frequency showed a 1.539-fold increased risk of SLE (95 % CI = 1.209–1.959, p = 0.0004). We also observed an increased frequency of STAT4 C/C and C/G genotypes in SLE patients with renal symptoms OR = 2.259 (1.365–3.738, p = 0.0014), (p_corr = 0.0238) and in SLE patients with neurologic manifestations OR = 2.867 (1.467–5.604, p = 0.0016), (p_corr = 0.0272). Moreover, we found a contribution of STAT4 C/C and C/G genotypes to the presence of the anti-snRNP Ab OR = 3.237 (1.667–6.288, p = 0.0003), (p_corr = 0.0051) and the presence of the anti-Scl-70 Ab OR = 2.665 (1.380–5.147, p = 0.0028), (p_corr = 0.0476). Our studies confirmed an association of the STAT4 C (rs7582694) variant with the development of SLE and occurrence of some clinical manifestations of the disease.

The genetics of lupus: a functional perspective

Systemic lupus erythematosus (SLE) is an autoimmune disease with a strong genetic component and is characterized by chronic inflammation and the production of anti-nuclear auto-antibodies. In the era of genome-wide association studies (GWASs), elucidating the genetic factors present in SLE has been a very successful endeavor; 28 confirmed disease susceptibility loci have been mapped. In this review, we summarize the current understanding of the genetics of lupus and focus on the strongest associated risk loci found to date (P <1.0 × 10−8). Although these loci account for less than 10% of the genetic heritability and therefore do not account for the bulk of the disease heritability, they do implicate important pathways, which contribute to SLE pathogenesis. Consequently, the main focus of the review is to outline the genetic variants in the known associated loci and then to explore the potential functional consequences of the associated variants. We also highlight the genetic overlap of these loci with other autoimmune diseases, which indicates common pathogenic mechanisms. The importance of developing functional assays will be discussed and each of them will be instrumental in furthering our understanding of these associated variants and loci. Finally, we indicate that performing a larger SLE GWAS and applying a more targeted set of methods, such as the ImmunoChip and next generation sequencing methodology, are important for identifying additional loci and enhancing our understanding of the pathogenesis of SLE.

Lupus nephritis: an overview of recent findings

Lupus nephritis (LN) is one of the most serious complications of systemic lupus erythematosus (SLE) since it is the major predictor of poor prognosis. In susceptible individuals suffering of SLE, in situ formation and deposit of immune complexes (ICs) from apoptotic bodies occur in the kidneys as a result of an amplified epitope immunological response. IC glomerular deposits generate release of proinflammatory cytokines and cell adhesion molecules causing inflammation. This leads to monocytes and polymorphonuclear cells chemotaxis. Subsequent release of proteases generates endothelial injury and mesangial proliferation. Presence of ICs promotes adaptive immune response and causes dendritic cells to release type I interferon. This induces maturation and activation of infiltrating T cells, and amplification of Th2, Th1 and Th17 lymphocytes. Each of them, amplify B cells and activates macrophages to release more proinflammatory molecules, generating effector cells that cannot be modulated promoting kidney epithelial proliferation and fibrosis. Herein immunopathological findings of LN are reviewed.

Activation of type I interferon pathway in systemic lupus erythematosus: association with distinct clinical phenotypes

Growing evidence over the last few years suggests a central role of type I IFN pathway in the pathogenesis of systemic autoimmune disorders. Data from clinical and genetic studies in patients with systemic lupus erythematosus (SLE) and lupus-prone mouse models, indicates that the type I interferon system may play a pivotal role in the pathogenesis of several lupus and associated clinical features, such as nephritis, neuropsychiatric and cutaneous lupus, premature atherosclerosis as well as lupus-specific autoantibodies particularly against ribonucleoproteins. In the current paper, our aim is to summarize the latest findings supporting the association of type I IFN pathway with specific clinical manifestations in the setting of SLE providing insights on the potential use of type I IFN as a therapeutic target.