Genetic regulation of serum cytokines in systemic lupus erythematosus

Tumor necrosis factor receptor II and PTPN22 genes polymorphisms and the risk of systemic lupus erythematosus in Egyptian children

BACKGROUND

Many genes have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). Tumor necrosis factor (TNF) is a potent cytokine stimulator acting through 2 cell surface receptors (TNFR I and II). TNFRII gene which controls expression of these receptors has been linked to SLE susceptibility through promoting apoptosis. Also; Protein tyrosine phosphatase non receptor 22 (PTPN22) gene enhances intrinsic phosphatase activity of T lymphocytes leading to their dysregulation and stimulates autoimmune process of lupus and its rs2476601 has been linked to susceptibility to thyroiditis in SLE patients in few studies.

OBJECTIVES

(i) to investigate the correlation between 2 SNPs of TNFR II and PTPN22 genes and SLE susceptibility in a cohort of Egyptian children compared to controls (ii) and to investigate their possible association with different clinical presentations of the disease in children.

SUBJECTS AND METHODS

Typing of TNFR II rs1061622 and PTPN22 rs2476601 SNPs were done using polymerase chain reaction-restriction fragment length polymorphism for 74 children with SLE and 100 matched healthy controls.

RESULTS

Children with SLE had more frequent G allele and GG genotype of TNFR II rs1061622 (p < 0.001) and more T allele and TT genotype of PTPN22 rs2476601 (p = 0.012 and <0.001, respectively) compared to controls. Only 6 patients (8%) had thyroiditis (hypothyroidism) with T allele and TT genotype of PTPN22 1858 T more prevalent in those patients versus those without thyroiditis (p ≤ 0.001). Apart from, thyroiditis, no significant association was found between genotypes and alleles frequencies of the 2 studied SNPs and other clinical manifestations of the disease.

CONCLUSION

The G allele and GG genotype of TNFR II rs1061622 and T allele and TT genotype of PTPN22 rs2476601 genes polymorphism can be considered as risk factors for the development of SLE. The presence of the T allele of PTPN22 rs2476601 may increase the risk of concomitant thyroiditis in Egyptian children with SLE but further studies are required to confirm this finding as thyroiditis was reported only in few cases in this study.

Association study between X-linked susceptibility genes and clinical features in Chinese female patients with systemic lupus erythematosus

Recent large-scale genetic association studies have identified that several single nucleotide polymorphisms (SNPs) on X chromosome are correlated with risk of systemic lupus erythematosus (SLE) in Chinese population. The aim of this study was to estimate association between these loci and clinical features in female patients with SLE. Six SNPs identified in previous studies were genotyped. Odds ratio (OR) was calculated with adjusting for potential confounding factors. A total of 772 SLE patients were included in the final analysis. The data showed that 3 SNPs (rs5914778, rs3853839 and rs1059702) were marginally associated with several clinical subphenotypes. Furthermore, consistent associations were also found in two independent cohorts. However, the cumulative genetic risk score (GRS) was not associated with clinical manifestations as well as the disease activity index at disease diagnosis. In summary, genetic variants in X-linked genes may be potentially associated with presence of specific clinical feature. Further studies in distinct ethnical populations are required to clarify the association between these loci and presence of SLE clinical features.

Novel genetic associations with interferon in systemic lupus erythematosus identified by replication and fine-mapping of trait-stratified genome-wide screen

BACKGROUND/PURPOSE

High serum interferon alpha (IFN-α) is an important heritable phenotype in systemic lupus erythematosus (SLE) which is involved in primary disease pathogenesis. High vs. low levels of IFN-α are associated with disease severity and account for some of the biological heterogeneity between SLE patients. The aim of the study was to replicate and fine-map previously detected genetic associations with serum IFN-α in SLE.

METHODS

We previously undertook a case-case genome-wide association study of SLE patients stratified by ancestry and extremes of phenotype in serum IFN-α. Single nucleotide polymorphisms (SNPs) in seven loci identified in this screen were selected for follow up in a large independent cohort of 1370 SLE patients (703 European-ancestry, 432 African ancestry, and 235 Amerindian ancestry). Each ancestral background was analyzed separately, and ancestry-informative markers were used to control for ancestry and admixture.

RESULTS

We find a rare haplotype spanning the promoter region of EFNA5 that is strongly associated with serum IFN-α in both African-American and European-American SLE patients (OR = 3.0, p = 3.7 × 10^-6). We also find SNPs in the PPM1H, PTPRM, and NRGN regions associated with IFN-α levels in European-American, Amerindian, and African-American SLE patients respectively. Many of these associations are within regulatory regions of the gene, suggesting an impact on transcription.

CONCLUSION

This study demonstrates the power of molecular sub-phenotypes to reveal genetic factors involved in complex autoimmune disease. The distinct associations observed in different ancestral backgrounds emphasize the heterogeneity of molecular pathogenesis in SLE.

MIF promotes a differential Th1/Th2/Th17 inflammatory response in human primary cell cultures: Predominance of Th17 cytokine profile in PBMC from healthy subjects and increase of IL-6 and TNF-α in PBMC from active SLE patients

Macrophage migration Inhibitory Factor (MIF) is a cytokine associated with the pathogenesis of autoimmune inflammatory diseases. There is evidence that MIF functions in a positive-feedback-loop with proinflammatory cytokines and could perpetuate the inflammatory process in Systemic Lupus Erythematosus (SLE).The aim of this study was to assess the effect of recombinant-human-MIF (rhMIF) on the expression of Th1, Th2 and Th17 cytokines in Peripheral Blood Mononuclear Cells (PBMC) from Healthy Subjects (HS) and SLE patients. The PBMC were isolated from SLE patients classified according to the 1997 SLE ACR criteria and HS donors; all subjects included were women from an unrelated Mexican-Mestizo population. The PBMC isolated were stimulated with rhMIF, LPS and ISO-1 in different combinations; Th1, Th2 and Th17cytokine profiles levels were determined by MAGPIX Bio-plex assay in supernatants from cell cultures. We observed in supernatants of PBMCs from HS treated with rhMIF a predominance of Th17 cytokine profile with an increase of IL-17A, IL-17F and IL-21 versus PBMCs from SLE patients, which showed an inflammatory profile represented by increase of IL-6 cytokine. According to SLE remission/activity presented at enrollment in the study (Mex-SLEDAI index), the PBMC from active SLE patients showed higher levels of TNF-α and IL-6 versus PBMC from remission SLE patients. In conclusion, our results suggest that MIF can induce a differential inflammatory response in physiological and pathological conditions with a predominance of a Th17 cytokine profile in PBMC from HS and an increase in TNF-α and IL-6 expression in PBMC from active SLE patients.

Human immune system variation

The human immune system is highly variable between individuals but relatively stable over time within a given person. Recent conceptual and technological advances have enabled systems immunology analyses, which reveal the composition of immune cells and proteins in populations of healthy individuals. The range of variation and some specific influences that shape an individual's immune system is now becoming clearer. Human immune systems vary as a consequence of heritable and non-heritable influences, but symbiotic and pathogenic microbes and other non-heritable influences explain most of this variation. Understanding when and how such influences shape the human immune system is key for defining metrics of immunological health and understanding the risk of immune-mediated and infectious diseases.

Human effector B lymphocytes express ARID3a and secrete interferon alpha

Previously, we determined that enhanced disease activity in patients with systemic lupus erythematosus (SLE) was associated with dramatic increases in numbers of B lymphocytes expressing the transcription factor ARID3a. Our data now indicate ARID3a is important for interferon alpha (IFNa) expression and show a strong association between ARID3a expression and transcription of genes associated with lupus IFN signatures. Furthermore, both ARID3a and IFNa production were elicited in healthy control B cells upon stimulation with the TLR 9 agonist, CpG. Importantly, secretion of IFNa from ARID3a⁺ healthy B lymphocytes stimulated increased IFNa production in plasmacytoid dendritic cells. These data identify ARID3a⁺ B cells as a novel type of effector B cell, and link ARID3a expression in B lymphocytes to IFN-associated inflammatory responses in SLE.

Inhibition of SHP2 ameliorates the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a devastating multisystemic autoimmune disorder. However, the molecular mechanisms underlying its pathogenesis remain elusive. Some patients with Noonan syndrome, a congenital disorder predominantly caused by gain-of-function mutations in the protein tyrosine phosphatase SH2 domain-containing PTP (SHP2), have been shown to develop SLE, suggesting a functional correlation between phosphatase activity and systemic autoimmunity. To test this directly, we measured SHP2 activity in spleen lysates isolated from lupus-prone MRL/lpr mice and found it was markedly increased compared with that in control mice. Similar increases in SHP2 activity were seen in peripheral blood mononuclear cells isolated from lupus patients relative to healthy patients. To determine whether SHP2 alters autoimmunity and related immunopathology, we treated MRL/lpr mice with an SHP2 inhibitor and found increased life span, suppressed crescentic glomerulonephritis, reduced spleen size, and diminished skin lesions. SHP2 inhibition also reduced numbers of double-negative T cells, normalized ERK/MAPK signaling, and decreased production of IFN-γ and IL-17A/F, 2 cytokines involved in SLE-associated organ damage. Moreover, in cultured human lupus T cells, SHP2 inhibition reduced proliferation and decreased production of IFN-γ and IL-17A/F, further implicating SHP2 in lupus-associated immunopathology. Taken together, these data identify SHP2 as a critical regulator of SLE pathogenesis and suggest targeting of its activity as a potent treatment for lupus patients.

Immunogenetics of systemic lupus erythematosus: A comprehensive review

Our understanding of the genetic basis of systemic lupus erythematosus has progressed rapidly in recent years. While many genetic polymorphisms have been associated with disease susceptibility, the next major step involves integrating these genetic polymorphisms into the molecular mechanisms and cellular immunology of the human disease. In this review, we summarize some recent work in this area, including the genetics of the type I IFN response in SLE, including polygenic and monogenic factors, as well as epigenetic influences. Contributions of both HLA and non-HLA polymorphisms to the complex genetics of SLE are reviewed. We also review recent reports of specific gene deficits leading to monogenic SLE-like syndromes. The molecular functions of common SLE-risk variants are reviewed in depth, including regulatory variations in promoter and enhancer elements and coding-change polymorphisms, and studies which are beginning to define the molecular and cellular functions of these polymorphisms in the immune system. We discuss epigenetic influences on lupus, with an emphasis on micro-RNA expression and binding, as well as epigenetic modifications that regulate the expression levels of various genes involved in SLE pathogenesis and the ways epigenetic marks modify SLE susceptibility genes. The work summarized in this review provides a fascinating window into the biology and molecular mechanisms of human SLE. Understanding the functional mechanisms of causal genetic variants underlying the human disease greatly facilitates our ability to translate genetic associations toward personalized care, and may identify new therapeutic targets relevant to human SLE disease mechanisms.

High Affinity Antibodies against Influenza Characterize the Plasmablast Response in SLE Patients After Vaccination

Breakdown of B cell tolerance is a cardinal feature of systemic lupus erythematosus (SLE). Increased numbers of autoreactive mature naïve B cells have been described in SLE patients and autoantibodies have been shown to arise from autoreactive and non-autoreactive precursors. How these defects, in the regulation of B cell tolerance and selection, influence germinal center (GC) reactions that are directed towards foreign antigens has yet to be investigated. Here, we examined the characteristics of post-GC foreign antigen-specific B cells from SLE patients and healthy controls by analyzing monoclonal antibodies generated from plasmablasts induced specifically by influenza vaccination. We report that many of the SLE patients had anti-influenza antibodies with higher binding affinity and neutralization capacity than those from controls. Although overall frequencies of autoreactivity in the influenza-specific plasmablasts were similar for SLE patients and controls, the variable gene repertoire of influenza-specific plasmablasts from SLE patients was altered, with increased usage of JH6 and long heavy chain CDR3 segments. We found that high affinity anti-influenza antibodies generally characterize the plasmablast responses of SLE patients with low levels of autoreactivity; however, certain exceptions were noted. The high-avidity antibody responses in SLE patients may also be correlated with cytokines that are abnormally expressed in lupus. These findings provide insights into the effects of dysregulated immunity on the quality of antibody responses following influenza vaccination and further our understanding of the underlying abnormalities of lupus.

Interferon regulatory factors: critical mediators of human lupus

The pathogenesis of systemic lupus erythematosus (SLE) is multifactorial, and the interferon regulatory factors (IRFs) play an important role. Autoantibodies formed in SLE target nuclear antigens, and immune complexes formed by these antibodies contain nucleic acid. These immune complexes can activate antiviral pattern recognition receptors (PRRs), resulting in the downstream activation of IRFs, which can induce type I interferon (IFN-I) and other inflammatory mediators. Genetic variations in IRFs have been associated with susceptibility to SLE, and current evidence supports the idea that these polymorphisms are gain of function in humans. Recent studies suggest that these genetic variations contribute to the break in humoral tolerance that allows for nucleic acid binding autoantibodies, and that the same polymorphisms also augment IFN-I production in the presence of these autoantibody immune complexes, forming a feed-forward loop. In this review, we will outline major features of the PRR/IRF systems and describe the role of the IRFs in human SLE pathogenesis.

Dysregulation of antiviral helicase pathways in systemic lupus erythematosus

In the autoimmune disease systemic lupus erythematosus (SLE), our normal antiviral defenses are inappropriately activated, resulting in over-activity of the type I interferon (IFN) pathway. This increased activity of the type I IFN pathway is an important primary pathogenic factor in the disease. Emerging evidence has implicated the antiviral helicases in this process. The antiviral helicases normally function as nucleic acid receptors in viral immunity. Genetic variations in antiviral helicase genes have been associated with SLE, supporting the idea that helicase pathways are involved in the primary pathogenesis of SLE. Studies have documented functional consequences of these genetic variations within the type I IFN pathway in human cell lines and SLE patients. In this review, we summarize the function of helicases in the anti-viral immune response, and how this response is dysregulated in SLE patients. In particular, we will focus on known functional genetic polymorphisms in the IFIH1 (MDA5) and mitochondrial antiviral signaling protein genes which have been implicated in human SLE. These data provide fascinating evidence for dysregulation of helicase-mediated innate immunity in SLE, and may support novel therapeutic strategies in the disease.

A multilocus genetic study in a cohort of Italian SLE patients confirms the association with STAT4 gene and describes a new association with HCP5 gene

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease with complex pathogenesis in which genes and environmental factors are involved. We aimed at analyzing previously identified loci associated with SLE or with other autoimmune and/or inflammatory disorders (STAT4, IL10, IL23R, IRAK1, PSORS1C1, HCP5, MIR146a, PTPN2, ERAP1, ATG16L1, IRGM) in a sample of Italian SLE patients in order to verify or confirm their possible involvement and relative contribution in the disease.

Materials and methods

Two hundred thirty-nine consecutive SLE patients and 278 matched healthy controls were enrolled. Study protocol included complete physical examination, and clinical and laboratory data collection. Nineteen polymorphisms were genotyped by allelic discrimination assays. A case-control association study and a genotype-phenotype correlation were performed.

Results

STAT4 was the most associated gene [P = 3×10⁻⁷, OR = 2.13 (95% CI: 1.59–2.85)]. IL10 confirmed its association with SLE [rs3024505: P = 0.02, OR = 1.52 (95% CI: 1.07–2.16)]. We describe a novel significant association between HCP5 locus and SLE susceptibility [rs3099844: P = 0.01, OR = 2.06 (95% CI: 1.18–3.6)]. The genotype/phenotype correlation analysis showed several associations including a higher risk to develop pericarditis with STAT4, and an association between HCP5 rs3099844 and anti-Ro/SSA antibodies.

Conclusions

STAT4 and IL10 confirm their association with SLE. We found that some SNPs in PSORS1C1, ATG16L1, IL23R, PTPN2 and MIR146a genes can determine particular disease phenotypes. HCP5 rs3099844 is associated with SLE and with anti-Ro/SSA. This polymorphism has been previously found associated with cardiac manifestations of SLE, a condition related with anti-Ro/SSA antibodies. Thus, our results may provide new insights into SLE pathogenesis.

Copy Number Variation of TLR-7 Gene and its Association with the Development of Systemic Lupus Erythematosus in Female Patients from Yucatan Mexico

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of autoantibodies against self-antigens, which occurs most often in women between 15 and 40 years of age. The innate immunity is involved in the pathogenesis of SLE through TLR- 7. Genetic factors such as copy number variation (CNV) of target genes may contribute to disease development, but this possible risk has not yet been studied in SLE patients from Yucatan, Mexico. The CNV of TLR-7 gene was determined by quantitative polymerase chain reaction assay using TaqMan probes in 80 SLE women and 150 control subjects. The results showed that 10% of SLE patients exhibited more than two copies of TLR-7 gene, whereas no mRNA overexpression was detected. These data suggested that increased CNV of the TLR-7 gene in Yucatan SLE women can be a risk factor for this disease.

Role of osteopontin in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystemic disease, caused by a variety of factors, which lead to immunological abnormalities. Osteopontin (OPN) is a pleiotropic protein, important in bone remodeling and immune system signaling. OPN, produced by various cells, including immune cells, plays a key role in regulating T-helper 1/T-helper 2 balance, stimulating B lymphocytes to produce antibodies, regulating macrophages, neutrophils and inducing dendritic cells. OPN expression is influenced by genetic polymorphisms of its promoter, hormones and cytokines. Over expression of OPN has been associated with the pathogenesis of immune-mediated diseases. OPN has been implicated in the development of murine model of lupus and in humans with SLE. In this review, I will present current state of research on the role of OPN and OPN gene polymorphisms in pathogenesis and clinical course of SLE. A better understanding of the role of OPN in SLE will contribute to more precise diagnosis and treatment of the disease.

Serum free light chains, interferon-alpha, and interleukins in systemic lupus erythematosus

OBJECTIVE

Interleukin-6 (IL-6), interleukin-10 (IL-10), interferon-alpha (IFN-α), and free light chains (FLCs: lambda, kappa) have all been noted to be of importance in systemic lupus erythematosus (SLE). Herein, we quantified and explored the relationship between these inflammatory mediators and disease activity in SLE; and stratified by their current anti-dsDNA antibody status.

METHODS

Seventy-seven SLE patients underwent assessment of disease activity using the SLE disease activity index (SLEDAI). Serum FLC (lambda, kappa, and total), IL-6, IL-10, and IFN-α were quantified. Demographics of disease characteristics were determined by chart reviews. Statistical analyses included Mann-Whitney test, chi square, and linear regression analyses.

RESULTS

Mean (SD) age of the patients was 44.9 ± 12.7 years; SLEDAI (mean ± SD) was 3.4 ± 4.0. Serum lambda FLC levels had a moderate correlation (r = 0.46 with physician global assessment, 0.44 with SLEDAI) and the strongest correlation with disease activity as compared with other inflammatory mediators including current dsDNA antibody status. After adjusting for prednisone use, the correlation of lambda FLC with PGA (r = 0.48) and SLEDAI (r = 0.52) was better than of current dsDNA antibody status with PGA (r = 0.33) and adjusted SLEDAI (r = 0.24), respectively. IL-10 and IFN-α activity did not correlate with disease activity. Serum FLC and IL-6 levels could differentiate between active and inactive SLE patients. Serum lambda FLC and IL-6 levels differed significantly among patients with and without current dsDNA antibodies. Serum lambda FLC levels accounted for 31% of variance in SLEDAI scores.

CONCLUSION

Serum FLC and IL-6 are potentially useful biomarkers of disease activity in SLE. Further studies, with larger study sample and longitudinal design, are indicated.

Insight into gene polymorphisms involved in toll-like receptor/interferon signalling pathways for systemic lupus erythematosus in South East Asia

Polymorphisms in genes involved in toll-like receptor/interferon signalling pathways have been reported previously to be associated with SLE in many populations. This study aimed to investigate the role of seven single nucleotide polymorphisms within TNFAIP3, STAT4, and IRF5, which are involved in upstream and downstream pathways of type I interferon production, in SLE in the South East Asian populations. Genotyping of 360 Malaysian SLE patients and 430 normal healthy individuals revealed that minor alleles of STAT4 rs7574865 and rs10168266 were associated with elevated risk of SLE in the Chinese and Malay patients, respectively (P = 0.028, odds ratio (OR) = 1.42; P = 0.035, OR = 1.80, respectively). Polymorphisms in TNFAIP3 and IRF5 did not show significant associations with SLE in any of the ethnicities. Combined analysis of the Malays, Chinese, and Indians for each SNP indicated that STAT4 rs10168266 was significantly associated with the Malaysian SLE as a whole (P = 0.014; OR = 1.435). The meta-analysis of STAT4 rs10168266, which combined the data of other studies and this study, further confirmed its importance as the risk factor for SLE by having pooled OR of 1.559 and P value of <0.001.

Macrophage migration inhibitory factor: association of -794 CATT5-8 and -173 G>C polymorphisms with TNF-α in systemic lupus erythematosus

Macrophage migration inhibitory factor (MIF) is an upstream immunoregulatory cytokine associated with the pathogenesis of autoimmune inflammatory diseases. There is evidence that MIF functions in a positive feedback loop with TNF-α that could perpetuate the inflammatory process in systemic lupus erythematosus (SLE). In this case-control study we investigated whether commonly occurring functional MIF polymorphisms are associated with SLE as well as with MIF and TNF-α serum levels in a Mexican-Mestizo population. Genotyping of the -794 CATT5-8 (rs5844572) and -173 G>C (rs755622) MIF polymorphisms was performed by PCR and PCR-RFLP, respectively in 186 SLE patients and 200 healthy subjects. MIF and TNF-α serum levels were determined by ELISA. A significant increase of MIF and TNF-α levels was found in SLE patients. According to a genetic model, we found a significant association of genotypes carrying the -794 CATT7 and -173(∗)C risk alleles with susceptibility to SLE and with a significant increase of TNF-α. In conclusion, MIF gene polymorphisms are associated with SLE susceptibility and with an increase of TNF-α serum levels in a Mexican-Mestizo population.

Nucleic Acid sensors and type I interferon production in systemic lupus erythematosus

The characteristic serologic feature of systemic lupus erythematosus (SLE) is autoantibodies against one’s own nucleic acid or nucleic acid-binding proteins – DNA and RNA-binding nuclear proteins. Circulating autoantibodies can deposit in the tissue, causing inflammation and production of cytokines such as type 1 interferon (IFN). Investigations in human patients and animal models have implicated environmental as well as genetic factors in the biology of the SLE autoimmune response. Viral/Bacterial nucleic acid is a potent stimulant of innate immunity by both toll-like receptor (TLR) and non-TLR signaling cascades. Additionally, foreign DNA may act as an immunogen to drive an antigen-specific antibody response. Self nucleic acid is normally restricted to the nucleus or the mitochondria, away from the DNA/RNA sensors, and mechanisms exist to differentiate between foreign and self nucleic acid. In normal immunity, a diverse range of DNA and RNA sensors in different cell types form a dynamic and integrated molecular network to prevent viral infection. In SLE, pathologic activation of these sensors occurs via immune complexes consisting of autoantibodies bound to DNA or to nucleic acid-protein complexes. In this review, we will discuss recent studies outlining how mismanaged nucleic acid sensing networks promote autoimmunity and result in the over-production of type I IFN. This information is critical for improving therapeutic strategies for SLE disease.

Familial aggregation of high tumor necrosis factor alpha levels in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) patients frequently have high circulating tumor necrosis factor alpha (TNF-α) levels. We explored circulating TNF-α levels in SLE families to determine whether high levels of TNF-α were clustered in a heritable pattern. We measured TNF-α in 242 SLE patients, 361 unaffected family members, 23 unaffected spouses of SLE patients, and 62 unrelated healthy controls. Familial correlations and relative recurrence risk rates for the high TNF-α trait were assessed. SLE-affected individuals had the highest TNF-α levels, and TNF-α was significantly higher in unaffected first degree relatives than healthy unrelated subjects (P = 0.0025). No Mendelian patterns were observed, but 28.4% of unaffected first degree relatives of SLE patients had high TNF-α levels, resulting in a first degree relative recurrence risk of 4.48 (P = 2.9 × 10⁻⁵). Interestingly, the median TNF-α value in spouses was similar to that of the first degree relatives. Concordance of the TNF-α trait (high versus low) in SLE patients and their spouses was strikingly high at 78.2%. These data support a role for TNF-α in SLE pathogenesis, and TNF-α levels may relate with heritable factors. The high degree of concordance in SLE patients and their spouses suggests that environmental factors may also play a role in the observed familial aggregation.

Genetic variation near IRF8 is associated with serologic and cytokine profiles in systemic lupus erythematosus and multiple sclerosis

Alleles of IRF8 are associated with susceptibility to both systemic lupus erythematosus (SLE) and multiple sclerosis (MS). While high type I interferon (IFN) is thought to be causal in SLE, type I IFN is used as a therapy in MS. We investigated whether IRF8 alleles were associated with type I IFN levels or serologic profiles in SLE and MS. Alleles which have been previously associated with SLE or MS were genotyped in SLE and MS patients. The MS-associated rs17445836G allele was associated with anti-dsDNA autoantibodies in SLE patients (meta-analysis OR=1.92). The same allele was associated with decreased serum IFN activity in SLE patients with anti-dsDNA antibodies, and with decreased type I IFN-induced gene expression in PBMC from anti-dsDNA negative SLE patients. In secondary progressive MS patients, rs17445836G was associated with decreased serum type I IFN. Rs17445836G was associated with increased IRF8 expression in SLE patient B cells. In summary, IRF8 rs17445836G is associated with human autoimmune disease characterized by low type I IFN levels, and this may have pharmacogenetic relevance as type I IFN is modulated in SLE and MS. The association with autoantibodies and increased IRF8 expression in B cells supports a role for rs17445836G in humoral tolerance.

MxA as a clinically applicable biomarker for identifying systemic interferon type I in primary Sjogren's syndrome

Objective

To establish an easy and practical assay for identifying systemic interferon (IFN) type I bioactivity in patients with primary Sjögren's syndrome (pSS). The IFN type I signature is present in over half of the pSS patients and identifies a subgroup with a higher disease activity. This signature is currently assessed via laborious expression profiles of multiple IFN type I-inducible genes.

Methods

In a cohort of 35 pSS patients, myxovirus-resistance protein A (MxA) was assessed as a potential biomarker for type I IFN activity, using an enzyme immunoassay (EIA) on whole-blood and flow cytometric analyses (fluorescence-activated cell sorting, FACS) of isolated CD14 monocytes. In addition, potential biomarkers such as CD64, CD169 and B cell-activating factor (BAFF) were simultaneously analysed in CD14 monocytes using FACS. The IFNscore, a measure for total type I IFN bioactivity, was calculated using expression values of the IFN type I signature genes—IFI44, IFI44L, IFIT3, LY6E and MX1—in CD14 monocytes, determined by real-time quantitative PCR.

Results

IFNscores correlated the strongest with monocyte MxA protein (r=0.741, p<0.001) and whole-blood MxA levels (r=0.764, p<0.001), weaker with CD169 (r=0.495, p<0.001) and CD64 (r=0.436, p=0.007), and not at all with BAFF protein. In particular, whole blood MxA levels correlated with EULAR Sjögren's Syndrome Disease Activity Index scores and numerous clinical pSS parameters. Interestingly, patients on hydroxychloroquine showed reduced MxA levels (EIA, p=0.04; FACS p=0.001).

Conclusions

The MxA assays were excellent tools to assess IFN type I activity in pSS, MxA-EIA being the most practical. MxA levels associate with features of active disease and are reduced in hydroxychloroquine-treated patients, suggesting the clinical applicability of MxA in stratifying patients according to IFN positivity.

Altered AKT1 and MAPK1 gene expression on peripheral blood mononuclear cells and correlation with T-helper-transcription factors in systemic lupus erythematosus patients

Kinases have been implicated in the immunopathological mechanisms of Systemic Lupus Erythematosus (SLE). v-akt murine-thymoma viral-oncogene-homolog 1 (AKT1) and mitogen-activated-protein-kinase 1 (MAPK1) gene expressions in peripheral mononuclear cells from thirteen SLE patients with inactive or mild disease were evaluated using quantitative real-time reverse-transcription polymerase-chain-reaction and analyzed whether there was any correlation with T-helper (Th) transcription factors (TF) gene expression, cytokines, and S100A8/S100A9-(Calprotectin). Age- and gender-matched thirteen healthy controls were examined. AKT1 and MAPK1 expressions were upregulated in SLE patients and correlated with Th17-(Retinoic acid-related orphan receptor (ROR)-C), T-regulatory-(Treg)-(Transforming Growth Factor Beta (TGFB)-2), and Th2-(interleukin (IL)-5)-related genes. MAPK1 expression correlated with Th1-(IL-12A, T-box TF-(T-bet)), Th2-(GATA binding protein-(GATA)-3), and IL-10 expressions. IL-10 expression was increased and correlated with plasma Tumor Necrosis Factor (TNF)-α and Th0-(IL-2), Th1-(IL-12A, T-bet), GATA3, Treg-(Forkhead/winged-helix transcription factor- (FOXP)-3), and IL-6 expressions. FOXP3 expression, FOXP3/RORC, and FOXP3/GATA3 expression ratios were increased. Plasma IL-1β, IL-12(p70), Interferon-(IFN)-γ, and IL-6 cytokines were augmented. Plasma IL-1β, IL-6, IL-2, IFN-γ, TNF-α, IL-10, and IL-13 correlated with C-reactive protein, respectively. Increased Calprotectin correlated with neutrophils. Conclusion, SLE patients presented a systemic immunoinflammatory activity, augmented AKT1 and MAPK1 expressions, proinflammatory cytokines, and Calprotectin, together with increased expression of Treg-related genes, suggesting a regulatory feedback opposing the inflammatory activity.

DNA methyltransferase 3B gene promoter and interleukin-1 receptor antagonist polymorphisms in childhood immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is one of the most common blood diseases as well as the commonest acquired bleeding disorder in childhood. Although the etiology of ITP is unclear, in the pathogenesis of the disease, both environmental and genetic factors including polymorphisms of TNF-a, IL-10, and IL-4 genes have been suggested to be involved. In this study, we investigated the rs2424913 single-nucleotide polymorphism (SNP) (C46359T) in DNA methyltransferase 3B (DNMT3B) gene promoter and the VNTR polymorphism of IL-1 receptor antagonist (IL-1 Ra) intron-2 in 32 children (17 boys) with the diagnosis of ITP and 64 healthy individuals. No significant differences were found in the genotype distribution of DNMT3B polymorphism between the children with ITP and the control group, whereas the frequency of allele T appeared significantly increased in children with ITP (P = 0.03, OR = 2, 95% CI: 1.06-3.94). In case of IL-1 Ra polymorphism, children with ITP had a significantly higher frequency of genotype I/II, compared to control group (P = 0.043, OR = 2.60, 95% CI: 1.02-6.50). Moreover, genotype I/I as well as allele I was overrepresented in the control group, suggesting that allele I may have a decreased risk for development of ITP. Our findings suggest that rs2424913 DNMT3B SNP as well as IL-1 Ra VNTR polymorphism may contribute to the susceptibility to ITP.

Gene-expression-guided selection of candidate loci and molecular phenotype analyses enhance genetic discovery in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a highly heterogeneous autoimmune disorder characterized by differences in autoantibody profiles, serum cytokines, and clinical manifestations. We have previously conducted a case-case genome-wide association study (GWAS) of SLE patients to detect associations with autoantibody profile and serum interferon alpha (IFN-α). In this study, we used public gene expression data sets to rationally select additional single nucleotide polymorphisms (SNPs) for validation. The top 200 GWAS SNPs were searched in a database which compares genome-wide expression data to genome-wide SNP genotype data in HapMap cell lines. SNPs were chosen for validation if they were associated with differential expression of 15 or more genes at a significance of P < 9 × 10(-5). This resulted in 11 SNPs which were genotyped in 453 SLE patients and 418 matched controls. Three SNPs were associated with SLE-associated autoantibodies, and one of these SNPs was also associated with serum IFN-α (P < 4.5 × 10(-3) for all). One additional SNP was associated exclusively with serum IFN-α. Case-control analysis was insensitive to these molecular subphenotype associations. This study illustrates the use of gene expression data to rationally select candidate loci in autoimmune disease, and the utility of stratification by molecular phenotypes in the discovery of additional genetic associations in SLE.

A study on the estrogen receptor α gene polymorphism and its expression in thin endometrium of unknown etiology

BACKGROUND/AIMS

To study the relationship between the estrogen receptor α (ERa) gene polymorphism and expression in thin endometrium.

METHODS

We chose 120 unknown thin endometrium patients as the case group and another 112 normal endometrium women as the control group. Methods in molecular biology were used to analyze restriction fragment length polymorphism of PvuII and XbaI in the ERa gene. RT-PCR and Western blot were used to investigate the expressions of the ERa at mRNA and protein levels.

RESULTS

P genotypic frequency was 47.1% in the case group and 30.0% in the control group; the OR was 2.076. X genotypic frequency in the case group was 20.8%, and 30.4% in the control group; the OR was 0.602. Restriction fragment length polymorphism of PvuII and XbaI in the two groups were distributed with polymorphisms. The mRNA and protein expressions of ERa decreased compared with that in the control group (p < 0.05).

CONCLUSIONS

ERa gene polymorphism is related to unknown thin endometrium, in which P allele may be the risk and X allele may be its guard factor. The expression of ERa decreases in thin endometrium compared with normal endometrium, and ERa may be related to the unknown etiological thin endometrium.

Hydroxychloroquine is associated with impaired interferon-alpha and tumor necrosis factor-alpha production by plasmacytoid dendritic cells in systemic lupus erythematosus

Introduction

Plasmacytoid dendritic cells (pDCs) constitutively express two members of the Toll-like receptor (TLR) family, TLR-9 and TLR-7, through which they can be stimulated to produce high levels of interferon (IFN)-α, a key mediator of the pathogenesis of systemic lupus erythematosus (SLE). Given the known efficacy of hydroxychloroquine (HCQ) in the treatment of SLE, we examined its ability to inhibit such pDC function in vivo.

Methods

Peripheral blood mononuclear cells (PBMCs) from SLE subjects treated or not with HCQ and from healthy controls were stimulated with the TLR-9 agonist, CpG oligodeoxynucleotides (CpG-A ODN)-2216, and the TLR-7 agonist, imiquimod. The proportion of monocytes, B cells, myeloid dendritic cells, pDCs, and natural killer (NK) cells producing IFN-α and tumor necrosis factor alpha (TNF-α) was then analyzed by multiparameter flow cytometry.

Results

After TLR-9/7 stimulation in both SLE and healthy subjects, significant production of IFN-α and TNF-α was only observed in pDCs. TLR-7 and TLR-9 induced IFN-α and TNF-α production by pDCs from subjects with SLE was decreased relative to that found in controls (TLR-9/IFN-α, P < 0.0001; TLR-9/TNF-α P < 0.0001; TLR-7/TNF-α P = 0.01). TLR-9 and TLR-7 induced IFN-α and TNF-α production by pDCs was severely impaired in 36% (TLR-9) and 33% (TLR-7) of SLE subjects. In almost all cases, these subjects were being treated with HCQ (HCQ vs. no HCQ: impaired TLR-9/IFN-α, P = 0.0003; impaired TLR-7/IFN-α, P = 0.07; impaired TLR-9/TNF-α, P < 0.009; impaired TLR-7/TNF-α, P < 0.01).

Conclusions

Treatment with HCQ is associated with impaired ability of pDCs from subjects with SLE to produce IFN-α and TNF-α upon stimulation with TLR-9 and TLR-7 agonists.

Myeloid dendritic cells from B6.NZM Sle1/Sle2/Sle3 lupus-prone mice express an IFN signature that precedes disease onset

Patients with systemic lupus erythematosus show an overexpression of type I IFN-responsive genes that is referred to as "IFN signature." We found that B6.NZMSle1/Sle2/Sle3 (Sle1,2,3) lupus-prone mice also express an IFN signature compared with non-autoimmune C57BL/6 mice. In vitro, myeloid dendritic cells (mDCs) (GM-CSF bone marrow-derived dendritic cells; BMDCs) from Sle1,2,3 mice constitutively overexpressed IFN-responsive genes such as IFN-β, Oas-3, Mx-1, ISG-15, and CXCL10 and members of the IFN signaling pathway STAT1, STAT2, and IRF7. The IFN signature was similar in Sle1,2,3 BMDCs from young, pre-autoimmune mice and from mice with high titers of autoantibodies, suggesting that the IFN signature in mDCs precedes disease onset and is independent from the autoantibodies. Sle1,2,3 BMDCs hyperresponded to stimulation with IFN-α and the TLR7 and TLR9 agonists R848 and CpGs. We propose that this hyperresponse is induced by the IFN signature and only partially contributes to the signature, as oligonucleotides inhibitory for TLR7 and TLR9 only partially suppressed the constitutive IFN signature, and pre-exposure to IFN-α induced the same hyperresponse in wild-type BMDCs as in Sle1,2,3 BMDCs. In vivo, mDCs and to a lesser extent T and B cells from young prediseased Sle1,2,3 mice also expressed the IFN signature, although they lacked the strength that BMDCs showed in vitro. Sle1,2,3 plasmacytoid DCs expressed the IFN signature in vitro but not in vivo, suggesting that mDCs may be more relevant before disease onset. We propose that Sle1,2,3 mice are useful tools to study the role of the IFN signature in lupus pathogenesis.

Interferons in autoimmune and inflammatory diseases: regulation and roles

Several lines of evidence strongly implicate type I interferons (IFN-α and β) and IFN-signaling in the pathogenesis of certain autoimmune inflammatory diseases. Accordingly, genome-wide association studies have identified polymorphisms in the type I IFN-signaling pathways. Other studies also indicate that a feed-forward loop of type I IFN production, which involves sensing of cytoplasmic nucleic acids by sensors, contributes to the development of immunopathology. In addition, a mutually positive regulatory feedback loop between type I IFNs and estrogen receptor-α may contribute to a gender bias, thus resulting in an increased production of type I IFNs and associated immunopathology in women. Increased levels of type I IFNs have numerous immunomodulatory functions for both the innate and adaptive immune responses. Given that the IFN-β also has some anti-inflammatory roles, identifying molecular links among certain genotypes, cytokine profiles, and associated phenotypes in patients with autoimmune inflammatory diseases is likely to improve our understanding of autoimmunity-associated pathogenesis and suboptimal outcomes following standard therapies.

Role of cytokines in systemic lupus erythematosus: recent progress from GWAS and sequencing

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder, known to have a strong genetic component. Concordance between monozygotic twins is approximately 30-40%, which is 8-20 times higher than that of dizygotic twins. In the last decade, genome-wide approaches to understanding SLE have yielded many candidate genes, which are important to understanding the pathophysiology of the disease and potential targets for pharmaceutical intervention. In this paper, we focus on the role of cytokines and examine how genome-wide association studies, copy number variation studies, and next-generation sequencing are being employed to understand the etiology of SLE. Prominent genes identified by these approaches include BLK, FCγR3B, and TREX1. Our goal is to present a brief overview of genomic approaches to SLE and to introduce some of the key discussion points pertinent to the field.

IRF5 haplotypes demonstrate diverse serological associations which predict serum interferon alpha activity and explain the majority of the genetic association with systemic lupus erythematosus

OBJECTIVE

High serum interferon α (IFNα) activity is a heritable risk factor for systemic lupus erythematosus (SLE). Auto-antibodies found in SLE form immune complexes which can stimulate IFNα production by activating endosomal Toll-like receptors and interferon regulatory factors (IRFs), including IRF5. Genetic variation in IRF5 is associated with SLE susceptibility; however, it is unclear how IRF5 functional genetic elements contribute to human disease.

METHODS

1034 patients with SLE and 989 controls of European ancestry, 555 patients with SLE and 679 controls of African-American ancestry, and 73 patients with SLE of South African ancestry were genotyped at IRF5 polymorphisms, which define major haplotypes. Serum IFNα activity was measured using a functional assay.

RESULTS

In European ancestry subjects, anti-double-stranded DNA (dsDNA) and anti-Ro antibodies were each associated with different haplotypes characterised by a different combination of functional genetic elements (OR>2.56, p<1.9×10(-14) for both). These IRF5 haplotype-auto-antibody associations strongly predicted higher serum IFNα in patients with SLE and explained >70% of the genetic risk of SLE due to IRF5. In African-American patients with SLE a similar relationship between serology and IFNα was observed, although the previously described European ancestry-risk haplotype was present at admixture proportions in African-American subjects and absent in African patients with SLE.

CONCLUSIONS

The authors define a novel risk haplotype of IRF5 that is associated with anti-dsDNA antibodies and show that risk of SLE due to IRF5 genotype is largely dependent upon particular auto-antibodies. This suggests that auto-antibodies are directly pathogenic in human SLE, resulting in increased IFNα in cooperation with particular combinations of IRF5 functional genetic elements. SLE is a systemic autoimmune disorder affecting multiple organ systems including the skin, musculoskeletal, renal and haematopoietic systems. Humoral autoimmunity is a hallmark of SLE, and patients frequently have circulating auto-antibodies directed against dsDNA, as well as RNA binding proteins (RBP). Anti-RBP autoantibodies include antibodies which recognize Ro, La, Smith (anti-Sm), and ribonucleoprotein (anti-nRNP), collectively referred to as anti-retinol-binding protein). Anti-retinol-binding protein and anti-dsDNA auto-antibodies are rare in the healthy population. These auto-antibodies can be present in sera for years preceding the onset of clinical SLE illness and are likely pathogenic in SLE.

The autoimmune disease risk allele of UBE2L3 in African American patients with systemic lupus erythematosus: a recessive effect upon subphenotypes

OBJECTIVE

UBE2L3 is associated with susceptibility to systemic lupus erythematosus (SLE) and rheumatoid arthritis in European ancestry populations, and this locus has not been investigated fully in non-European populations. We studied the UBE2L3 risk allele for association with SLE, interferon-α (IFN-α), and autoantibodies in a predominantly African American SLE cohort.

METHODS

We studied 395 patients with SLE and 344 controls. The UBE2L3 rs5754217 polymorphism was genotyped using Taqman primer-probe sets, and IFN-α was measured using a reporter cell assay.

RESULTS

The UBE2L3 rs5754217 T allele was strongly enriched in African American patients with anti-La antibodies as compared to controls, and a recessive model was the best fit for this association (OR 2.55, p = 0.0061). Serum IFN-α also demonstrated a recessive association with the rs5754217 genotype in African American patients, and the TT/anti-La-positive patients formed a significantly high IFN-α subgroup (p = 0.0040). Similar nonstatistically significant patterns of association were observed in the European American patients with SLE. Case-control analysis did not show large allele frequency differences, supporting the idea that this allele is most strongly associated with anti-La-positive patients.

CONCLUSION

This pattern of recessive influence within a subgroup of patients may explain why this allele does not produce a strong signal in standard case-control studies, and subphenotypes should be included in future studies of UBE2L3. The interaction we observed between UBE2L3 genotype and autoantibodies upon serum IFN-α suggests a biological role for this locus in patients with SLE in vivo.

Linkage of type I interferon activity and TNF-alpha levels in serum with sarcoidosis manifestations and ancestry

Background

Both type I interferon (IFN), also known as IFN-α and tumor necrosis factor alpha (TNF-α) have been implicated in the pathogenesis of sarcoidosis. We investigated serum levels of these cytokines in a large multi-ancestral sarcoidosis population to determine correlations between cytokine levels and disease phenotypes.

Methods

We studied serum samples from 98 patients with sarcoidosis, including 71 patients of African-American ancestry and 27 patients of European-American ancestry. Serum type I IFN was measured using a sensitive reporter cell assay and serum TNF-α was measured using a commercial ELISA kit. Clinical data including presence or absence of neurologic, cardiac, and severe pulmonary manifestations of sarcoidosis were abstracted from medical records. Twenty age-matched non-autoimmune controls were also studied from each ancestral background. Differences in cytokine levels between groups were analyzed with Mann-Whitney U test, and correlations were assessed using Spearman's rho. Multivariate logistic regression models were used to detect associations between cytokines and clinical manifestations.

Results

Significant differences in cytokine levels were observed between African- and European-American patients with sarcoidosis. In African-Americans, serum TNF-α levels were significantly higher relative to matched controls (P = 0.039), and patients with neurologic disease had significantly higher TNF-α than patients lacking this manifestation (P = 0.022). In European-Americans, serum type I IFN activity was higher in sarcoidosis cases as compared to matched controls, and patients with extra-pulmonary disease represented a high serum IFN subgroup (P = 0.0032). None of the associations observed were shared between the two ancestral groups.

Conclusions

Our data indicate that significant associations between serum levels of TNF-α and type I IFN and clinical manifestations exist in a sarcoidosis cohort that differ significantly by self-reported ancestry. In each ancestral background, the cytokine elevated in patients with sarcoidosis was also associated with a particular disease phenotype. These findings may relate to ancestral differences in the molecular pathogenesis of this heterogeneous disease.

Osteopontin alleles are associated with clinical characteristics in systemic lupus erythematosus

Variants of the osteopontin (OPN) gene have been associated with systemic lupus erythematosus (SLE) susceptibility and cytokine profiles in SLE patients. It is not known whether these alleles are associated with specific clinical phenotypes in SLE. We studied 252 well-characterized SLE patients from a multiethnic cohort, genotyping the rs11730582, rs28357094, rs6532040, and rs9138 SNPs in the OPN gene. Ancestry informative markers were used to control for genetic ancestry. The SLE-risk allele rs9138C in the 3′ UTR region was associated with photosensitivity in lupus patients across all ancestral backgrounds (meta-analysis OR = 3.2, 95% CI = 1.6–6.5, P = 1.0 × 10⁻³). Additionally, the promoter variant rs11730582C demonstrated suggestive evidence for association with two hematologic traits: thrombocytopenia (OR = 2.1, P = 0.023) and hemolytic anemia (OR = 2.6, P = 0.036). These clinical associations with SNPs in the promoter and 3′ UTR regions align with previously reported SLE-susceptibility SNPs in OPN and suggest potential roles for these variants in antibody-mediated cytopenias and skin inflammation in SLE.

Interferon alpha as a primary pathogenic factor in human lupus

Interferon alpha (IFN-α) is a critical mediator of human systemic lupus erythematosus (SLE). This review will summarize evidence supporting the role for IFN-α in the initiation of human SLE. IFN-α functions in viral immunity at the interface of innate and adaptive immunity, a position well suited to setting thresholds for autoimmunity. Some individuals treated with IFN-α for chronic viral infections develop de novo SLE, which frequently resolves when IFN-α is withdrawn, supporting the idea that IFN-α was causal. Abnormally high IFN-α levels are clustered within SLE families, suggesting that high serum IFN-α is a heritable risk factor for SLE. Additionally, SLE-risk genetic variants in the IFN-α pathway are gain of function in nature, resulting in either higher circulating IFN-α levels or greater sensitivity to IFN-α signaling in SLE patients. A recent genome-wide association study has identified additional novel genetic loci associated with high serum IFN-α in SLE patients. These data support the idea that genetically determined endogenous elevations in IFN-α predispose to human SLE. It is possible that some of these gain-of-function polymorphisms in the IFN-α pathway are useful in viral defense, and that risk of SLE is a burden we have taken on in the fight to defend ourselves against viral infection.

The role of cytokines in the pathogenesis and treatment of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that is characterized by a defect in immune tolerance and exacerbated by both the innate and adaptive arms of the immune response. SLE-associated immune hyperactivity can be detected systemically as elevations in levels of cytokines along with their upregulated receptors expressed by hematopoietic cells. Importantly, increased levels of cytokines and their receptors can be observed in target organs, and it is clear that they have important roles in disease pathogenesis. Recent therapeutic strategies have focused on proximal cytokines, such as interferon-α, interleukin (IL)-1, IL-6, and tumor necrosis factor as a result of the efficacious use of biologic agents for intervention in rheumatoid arthritis and other autoimmune diseases. Despite the recent advances in understanding the cytokine networks involved in autoimmune diseases and more specifically in SLE, the diagnosis and prognosis of lupus remain a challenge. Lupus is heterogeneous and unpredictable; moreover, the frequency and severity of flares can be difficult to determine and treat. A better understanding of the regulation of expression of key cytokines and their receptors can likely provide important clues to the pathogenic mechanisms underlying specific forms of SLE, and pave the way toward more effective therapeutics.

Autoimmune disease risk variant of IFIH1 is associated with increased sensitivity to IFN-α and serologic autoimmunity in lupus patients

Increased IFN-α signaling is a heritable risk factor for systemic lupus erythematosus (SLE). IFN induced with helicase C domain 1 (IFIH1) is a cytoplasmic dsRNA sensor that activates IFN-α pathway signaling. We studied the impact of the autoimmune-disease-associated IFIH1 rs1990760 (A946T) single nucleotide polymorphism upon IFN-α signaling in SLE patients in vivo. We studied 563 SLE patients (278 African-American, 179 European-American, and 106 Hispanic-American). Logistic regression models were used to detect genetic associations with autoantibody traits, and multiple linear regression was used to analyze IFN-α-induced gene expression in PBMCs in the context of serum IFN-α in the same blood sample. We found that the rs1990760 T allele was associated with anti-dsDNA Abs across all of the studied ancestral backgrounds (meta-analysis odds ratio = 1.34, p = 0.026). This allele also was associated with lower serum IFN-α levels in subjects who had anti-dsDNA Abs (p = 0.0026). When we studied simultaneous serum and PBMC samples from SLE patients, we found that the IFIH1 rs1990760 T allele was associated with increased IFN-induced gene expression in PBMCs in response to a given amount of serum IFN-α in anti-dsDNA-positive patients. This effect was independent of the STAT4 genotype, which modulates sensitivity to IFN-α in a similar way. Thus, the IFIH1 rs1990760 T allele was associated with dsDNA Abs, and in patients with anti-dsDNA Abs this risk allele increased sensitivity to IFN-α signaling. These studies suggest a role for the IFIH1 risk allele in SLE in vivo.

Interleukin-10 receptor expression and signalling were down-regulated in CD4⁺ T cells of lupus nephritis patients

Studies have indicated that interleukin (IL)-10 has a pathogenic role in systemic lupus erythematosus (SLE); however, a protective effect of IL-10 in SLE was also observed. Because the exact mechanism of IL-10 signalling in the pathogenesis of SLE is unclear, this study sought to assess the expression and signalling of interleukin-10 receptor (IL-10R) in peripheral leucocytes from patients with SLE. We used flow cytometry to examine the expression of IL-10R1 on different peripheral leucocytes from 28 SLE patients, of whom 14 had lupus nephritis (LN) and 14 were healthy controls. We also examined the effects of IL-10 on phosphorylation of signal transducer and activator of transcription (STAT)-3 and STAT-1 in peripheral blood mononuclear cells (PBMCs) obtained from 13 SLE patients and seven healthy controls. Plasma cytokines were detected by flow cytometric bead array (CBA) techniques. Although IL-10R1 expression levels on each peripheral leucocyte subset from 28 SLE patients and 14 healthy controls were similar, the expression levels on CD4(+) T cells from LN patients were significantly lower than on CD4(+) T cells from controls and SLE patients without nephritis (P < 0·01). IL-10R1 expression levels on CD4(+) and CD8(+) T cells were correlated negatively with the SLE disease activity index (P < 0·01). Additionally, the phosphorylation of STAT-3 was delayed and reduced in PBMCs from LN patients and active SLE patients. Plasma IL-10 levels were significantly higher in LN patients than controls. IL-10R1 expression on CD4(+) T cells and signalling in PBMCs were down-regulated in LN patients, indicating that IL-10 and its receptor may have a special role in LN pathogenesis.

Interferon regulatory factors in human lupus pathogenesis

Systemic lupus erythematosus (SLE) is a severe multisystem autoimmune disease that results from both genetic predisposition and environmental factors. Many lines of investigation support interferon alpha (IFN-α) as a causal agent in human lupus, and high levels of serum IFN-α are a heritable risk factor for SLE. Interferon regulatory factors (IRFs) are a family of transcription factors involved in host defense, which can induce transcription of IFN-α and other immune response genes after activation. In SLE, circulating immune complexes that contain nucleic acid are prevalent. These complexes are recognized by endosomal Toll-like receptors, resulting in activation of downstream IRF proteins. Genetic variants in the IRF5 and IRF7 genes have been associated with SLE susceptibility, and these same variants are associated with increased serum IFN-α in SLE patients. The increase in serum IFN-α related to IRF5 and 7 genotypes is observed only in patients with particular antibody specificities. This suggests that chronic stimulation of the endosomal Toll-like receptors by autoantibody immune complexes is required for IRF SLE-risk variants to cause elevation of circulating IFN-α and subsequent risk of SLE. Recently, genetic variation in the IRF8 gene has been associated with SLE and multiple sclerosis, and studies support an impact of IRF8 genotype on the IFN-α pathway. In summary, the SLE-associated polymorphisms in the IRF family of proteins seem to be gain-of-function variants, and understanding the impact of these variants on the IFN-α pathway in vivo may guide therapeutic strategies directed at the Toll-like receptor/IRF/IFN-α pathway in SLE.

Network analysis of associations between serum interferon-α activity, autoantibodies, and clinical features in systemic lupus erythematosus

OBJECTIVE

Interferon-α (IFNα) is a primary pathogenic factor in systemic lupus erythematosus (SLE), and high IFNα levels may be associated with particular clinical manifestations. The prevalence of individual clinical and serologic features differs significantly by ancestry. This study was undertaken to detect associations between clinical and serologic disease manifestations and serum IFNα activity in a large diverse SLE cohort, using multivariate and network analyses.

METHODS

We studied 1,089 SLE patients (387 African American, 186 Hispanic American, and 516 European American patients). The presence or absence of individual American College of Rheumatology (ACR) clinical criteria for SLE, autoantibodies, and serum IFNα activity data were analyzed in univariate and multivariate models. Iterative multivariate logistic regression was performed in each ancestral background group separately to establish the network of associations between variables that were independently significant following Bonferroni correction.

RESULTS

In all ancestral backgrounds, high IFNα activity was associated with anti-Ro and anti-double-stranded DNA antibodies (P = 4.6 × 10(-18) and P = 2.9 × 10(-16) , respectively). Younger age, non-European ancestry, and anti-RNP were also independently associated with increased serum IFNα activity (P ≤ 6.7 × 10(-4) ). We found 14 unique associations between variables in network analysis, and only 7 of these associations were shared among >1 ancestral background. Associations between clinical criteria were different for different ancestral backgrounds, while autoantibody-IFNα relationships were similar across backgrounds. IFNα activity and autoantibodies were not associated with ACR clinical features in multivariate models.

CONCLUSION

Our findings indicate that serum IFNα activity is strongly and consistently associated with autoantibodies, and not independently associated with clinical features in SLE. IFNα may be more relevant to humoral tolerance and initial pathogenesis than later clinical disease manifestations.

Familial aggregation of autoimmune disease in juvenile dermatomyositis

OBJECTIVE

Familial aggregation of autoimmune diseases likely reflects shared pathogenic factors between different diseases. Familial aggregation of autoimmunity has not been examined in juvenile dermatomyositis. Interferon-α is thought to be a pathogenic factor in both systemic lupus erythematosus and juvenile dermatomyositis, and we have previously demonstrated familial aggregation of serum interferon-α.

METHODS

Family histories were obtained from 304 families of children with juvenile dermatomyositis via 3-generation structured interviews performed by the same person. Rates of autoimmune disease in families of children with juvenile dermatomyositis were compared with published population rates. Serum interferon-α, tumor necrosis factor-α, and neopterin were measured using standard techniques.

RESULTS

A total of 51% of families of children with juvenile dermatomyositis reported at least 1 additional member affected by an autoimmune disease. In particular, both type 1 diabetes and systemic lupus erythematosus were significantly more common than would be expected (odds ratio >5, P ≤ 1 × 10(-7) for both). Pedigree analysis showed particularly strong familial clustering of systemic lupus erythematosus with little decrease in incidence across generations, suggesting the possibility of rare causal genes with large effect. Untreated subjects with juvenile dermatomyositis with a family history of systemic lupus erythematosus had higher serum interferon-α than those who did not (P = .047).

CONCLUSIONS

We find strong familial aggregation of specific autoimmune diseases in families of children with juvenile dermatomyositis, suggesting that these conditions share pathogenic factors. Higher serum interferon-α in juvenile dermatomyositis patients with a family history of systemic lupus erythematosus suggesting that interferon-α is one such shared factor.

The unexplained female predominance of systemic lupus erythematosus: clues from genetic and cytokine studies

Despite recent progress in the understanding of systemic lupus erythematosus (SLE), the striking 9:1 female to male ratio of disease incidence remains largely unexplained. In addition, peak SLE incidence rates occur during the early reproductive years in women. Studies which illuminate potential causes underlying this sex difference and characteristic onset during the reproductive years have the potential to fundamentally advance our understanding of disease pathogenesis in SLE. Similarly, progress in this area will likely inform human reproductive immunology. Studies of sex hormone function in the immune system are of obvious importance; however, it seems likely that many other types of sex-related genetic and immunological differences will contribute to SLE. In this review, we will focus on recent work in sex-related differences in cytokine pathways and genetics of these pathways as they relate to SLE pathogenesis. It seems quite possible that many of these sex-related differences could be important to reproductive fitness, which may explain the conservation of these immune system features and the observed female predominance of SLE.

Analysis of the influence of PTPN22 gene polymorphisms in systemic sclerosis

OBJECTIVE

Two functional single nucleotide polymorphisms (SNP) in the PTPN22 gene (rs24746601 and rs33996649) have been associated with autoimmunity. The aim of this study was to investigate the role of the R263Q SNP for the first time and to re-evaluate the role of the R620W SNP in the genetic predisposition to systemic sclerosis (SSc) susceptibility and clinical phenotypes.

METHODS

3422 SSc patients (2020 with limited cutaneous SSc and 1208 with diffuse cutaneous SSc) and 3638 healthy controls of Caucasian ancestry from an initial case--control set of Spain and seven additional independent replication cohorts were included in our study. Both rs33996649 and rs2476601 PTPN22 polymorphisms were genotyped by TaqMan allelic discrimination assay. A meta-analysis was performed to test the overall effect of these PTPN22 polymorphisms in SSc.

RESULTS

The meta-analysis revealed evidence of association of the rs2476601 T allele with SSc susceptibility (p(FDRcorrected)=0.03 pooled, OR 1.15, 95% CI 1.03 to 1.28). In addition, the rs2476601 T allele was significantly associated with anticentromere-positive status (p(FDRcorrected)=0.02 pooled, OR 1.22, 95% CI 1.05 to 1.42). Although the rs33996649 A allele was significantly associated with SSc in the Spanish population (p(FDRcorrected)=0.04, OR 0.58, 95% CI 0.36 to 0.92), this association was not confirmed in the meta-analysis (p=0.36 pooled, OR 0.89, 95% CI 0.72 to 1.1).

CONCLUSION

The study suggests that the PTPN22 R620W polymorphism influences SSc genetic susceptibility but the novel R263Q genetic variant does not. These data strengthen evidence that the R620W mutation is a common risk factor in autoimmune diseases.

Drug-induced granulomatous interstitial nephritis in a patient with ankylosing spondylitis during therapy with adalimumab

Tumor necrosis factor α (TNF-α) inhibitors are used in the treatment of rheumatoid arthritis, psoriasis, psoriatic arthritis, Crohn disease, ankylosing spondylitis, and juvenile idiopathic arthritis. Use of TNF inhibitors is associated with the induction of autoimmunity (systemic lupus erythematosus, vasculitis, psoriasis, and sarcoidosis/sarcoid-like granulomas). We report a case of interstitial granulomatous nephritis in a patient with ankylosing spondylitis after 18 months of treatment with adalimumab. Previously reported cases of sarcoid-like reactions secondary to the use of TNF-α inhibitors involved the liver, lung, lymph nodes, central nervous system, and skin. Granulomatous nephritis after adalimumab treatment has not been described. Close observation of patients undergoing treatment with TNF inhibitors for evolving signs and symptoms of autoimmunity is required. Organ involvement is unpredictable, which makes correct diagnosis and management extremely challenging.

Trait-stratified genome-wide association study identifies novel and diverse genetic associations with serologic and cytokine phenotypes in systemic lupus erythematosus

Introduction

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder, characterized by differences in autoantibody profile, serum cytokines, and clinical manifestations. SLE-associated autoantibodies and high serum interferon alpha (IFN-α) are important heritable phenotypes in SLE which are correlated with each other, and play a role in disease pathogenesis. These two heritable risk factors are shared between ancestral backgrounds. The aim of the study was to detect genetic factors associated with autoantibody profiles and serum IFN-α in SLE.

Methods

We undertook a case-case genome-wide association study of SLE patients stratified by ancestry and extremes of phenotype in serology and serum IFN-α. Single nucleotide polymorphisms (SNPs) in seven loci were selected for follow-up in a large independent cohort of 538 SLE patients and 522 controls using a multi-step screening approach based on novel metrics and expert database review. The seven loci were: leucine-rich repeat containing 20 (LRRC20); protein phosphatase 1 H (PPM1H); lysophosphatidic acid receptor 1 (LPAR1); ankyrin repeat and sterile alpha motif domain 1A (ANKS1A); protein tyrosine phosphatase, receptor type M (PTPRM); ephrin A5 (EFNA5); and V-set and immunoglobulin domain containing 2 (VSIG2).

Results

SNPs in the LRRC20, PPM1H, LPAR1, ANKS1A, and VSIG2 loci each demonstrated strong association with a particular serologic profile (all odds ratios > 2.2 and P < 3.5 × 10^-4). Each of these serologic profiles was associated with increased serum IFN-α. SNPs in both PTPRM and LRRC20 were associated with increased serum IFN-α independent of serologic profile (P = 2.2 × 10^-6 and P = 2.6 × 10^-3 respectively). None of the SNPs were strongly associated with SLE in case-control analysis, suggesting that the major impact of these variants will be upon subphenotypes in SLE.

Conclusions

This study demonstrates the power of using serologic and cytokine subphenotypes to elucidate genetic factors involved in complex autoimmune disease. The distinct associations observed emphasize the heterogeneity of molecular pathogenesis in SLE, and the need for stratification by subphenotypes in genetic studies. We hypothesize that these genetic variants play a role in disease manifestations and severity in SLE.