Interleukin-6 promoter polymorphism -174 G/C is associated with nephritis in Portuguese Caucasian systemic lupus erythematosus patients

The Association between Interleukin-6 Gene Polymorphisms and Risk of Systemic Lupus Erythematosus: A Meta-analysis with Trial Sequential Analysis

BACKGROUND

Molecular epidemiological studies have sought associations between interleukin-6 (IL-6) polymorphisms and the risk of systemic lupus erythematosus (SLE); however, the results are controversial. Therefore, we conducted a meta-analysis with trial sequential analysis to evaluate a more accurate estimation of the associations.

METHODS

Published literatures reporting the relationships of two IL-6 polymorphisms (G-174C and G-572C) and SLE risk were retrieved from electronic databases such as PubMed and EMBASE. The most appropriate genetic model was chosen for each polymorphism. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Trial sequential analysis (TSA) was introduced to assess the information size and the positive results.

RESULTS

With 17 studies (2780 cases and 3100 controls) included, a dominant association (CC+GC vs. GG) was suggested for G-174C polymorphism, and compared with the GG genotype, the CC+GC genotype of G-174C was associated with a decreased SLE risk (OR = 0.71; 95% CI = 0.56-0.88, P =.02). No association was found for G-572C under all genetic models (e.g. OR and 95%CI for CC+GC vs. GG: 0.89, 0.73-1.08, P =.22). Subgroup analyses indicated that SLE risk decreased in G-174C polymorphism by subgroups of Caucasian population, publications after 2010, studies with high quality, and studies complied with Hardy-Weinberg equilibrium (HWE). TSA suggested that the sample sizes used for G-572C were insufficient.

CONCLUSION

We found that the minor allele C of IL6G-174C polymorphism is a protective factor in SLE. Further studies with a larger sample size are needed to confirm the null association for G-572C.

Association of IL -6 -174 G>C polymorphism with the risk of SLE among south Indians: evidence from case-control study and meta-analysis

Cytokines play a direct role in disease pathogenesis of systemic lupus erythematosus (SLE). Elevated levels of serum IL-6 are well documented with the disease activity and anti-dsDNA antibodies in SLE. The 5' promoter region of the IL-6 gene has been shown to play a significant role in the regulation of gene expression. In view of this, the current study aimed to investigate the possible association of 5' promoter polymorphisms G-597A (rs1800797), G-572C (rs1800796) and G-174C (rs1800795) with the risk of SLE. Analysis of 468 subjects (202 SLE patients and 266 controls) showed a significant association of the -174 G/C variant with the SLE risk in both dominant and recessive model (odds ratio (OR) 3.20, 95% confidence interval (CI) 1.18-8.69, P = 0.020 and OR 2.02, 95% CI 1.35-3.02, P = 0.0005), respectively. The 'G allele of the -174 loci (OR 1.97, 95% CI 1.39-2.78, P = 0.00012) has shown significant distribution between the cases and controls. The haplotype analysis revealed that AGG haplotype carriers are more frequent in cases than controls and found a significant positive association (OR 1.394, 95% CI 1.07-7.12, P = 0.028) with SLE. In addition, we also undertook a meta-analysis on 13 study groups for -174 G/C, comprising a total of 1585 cases and 1690 controls. The pooled OR also suggested a significant association of -174 G/C with SLE (OR 1.36, 95% CI 1.22-1.53, P < 0.05). In conclusion, the presence of the G allele at the IL-6 polymorphic promoter loci -174 is a risk factor and might influence SLE disease and pathogenesis. Meta-analysis has also suggested the overall correlation between -174 G/C polymorphism and SLE risk.

Interleukin-6 Signaling Pathway and Its Role in Kidney Disease: An Update

Interleukin-6 (IL-6) is a pleiotropic cytokine that not only regulates the immune and inflammatory response but also affects hematopoiesis, metabolism, and organ development. IL-6 can simultaneously elicit distinct or even contradictory physiopathological processes, which is likely discriminated by the cascades of signaling pathway, termed classic and trans-signaling. Besides playing several important physiological roles, dysregulated IL-6 has been demonstrated to underlie a number of autoimmune and inflammatory diseases, metabolic abnormalities, and malignancies. This review provides an overview of basic concept of IL-6 signaling pathway as well as the interplay between IL-6 and renal-resident cells, including podocytes, mesangial cells, endothelial cells, and tubular epithelial cells. Additionally, we summarize the roles of IL-6 in several renal diseases, such as IgA nephropathy, lupus nephritis, diabetic nephropathy, acute kidney injury, and chronic kidney disease.

Genetic Variants That Are Associated with Neuropsychiatric Systemic Lupus Erythematosus

OBJECTIVE

While genetic risks have been implicated in systemic lupus erythematosus (SLE), the involvement of various genotypes in neuropsychiatric SLE (NPSLE) remains uncertain. The present metaanalysis aimed to combine data from different studies and evaluate the association between each genotype and the risk of developing NPSLE.

METHODS

Studies were searched and retrieved from online databases (PubMed, EMBASE, BIOSIS, and ScienceDirect). Case-control studies were chosen if they reported genotype frequencies of the γ Fc region (FCγR) receptors II-A, III-A, and III-B; tumor necrosis factor-α (TNF-α); mannan-binding lectin (MBL); integrin alpha M (ITGAM); interleukin (IL) 1, IL-1β, and IL-6; IL-10 promoter; and vitamin D genes. The OR were used to assess the strength of this association between patients with NPSLE and SLE.

RESULTS

A total of 33 studies were considered in this metaanalysis. The results suggest that these genotypes demonstrated a significant association with NPSLE: the homozygous FCγR IIIa 158 FF genotype (OR 1.89, p = 0.03 for FF vs VV + FV), heterozygous FCγR IIIb NA1/2 genotype (OR 2.14, p = 0.03 for NA1/2 vs NA1/1; OR 1.81, p = 0.04 for NA1/2 vs NA1/1 + NA2/2), and homozygous ITGAM rs1143679 HH genotype (OR 3.39, p = 0.04 for HH vs RH; OR 3.11, p = 0.048 for HH vs RR + RH). Polymorphisms of the TNF-α, MBL2, IL-1, IL-1β, IL-6, IL-10 promoter, and vitamin D receptor genes did not show a statistically significant association with the risk of developing NPSLE (p > 0.05).

CONCLUSION

This metaanalysis indicates that polymorphisms in the pathways of immune complex clearance, such as the FcγRIIIa, FcγRIIIb, and ITGAM genotypes, are potential susceptibility genes for NPSLE.

Genetic polymorphisms of interleukin 6 and interleukin 10 in Egyptian patients with systemic lupus eythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Cytokine gene polymorphisms play an important role in SLE. Thus, this study aimed to investigate the associations between interleukin 6 (IL-6) and interleukin 10 (IL-10) promoter single-nucleotide polymorphisms (SNPs) and their susceptibility to SLE and the implications for plasma levels. We genotyped IL-6-174G/C (rs1800795) using mutagenically separated polymerase chain reaction (MS-PCR) and IL-10-1082G/A (rs1800896) and -819C/T (rs1800871) using sequence specific primer polymerase chain reaction (SSP-PCR) in 100 Egyptian patients and 119 controls. The plasma levels of IL-6 and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). There was significant increase in the frequency of IL-6 (-174) GG genotype ( P < 0.05) and G allele ( P < 0.01) compared to controls. A significant increase in the distribution of IL-10 (-1082G/A) GG ( P < 0.05) and AA ( P < 0.05) genotypes and a significant reduction in the frequency of GA genotype ( P < 0.05) was found in SLE patients. The mean serum concentration of IL-6 ( P < 0.001) and IL-10 ( P < 0.001) was significantly elevated in SLE patients compared to healthy controls. There was no  significant association of the most common clinical findings and IL-6 and IL-10 gene polymorphisms in SLE patients. In conclusion, our preliminary study indicated that both GG genotype and G allele of IL-6 (-174G/C) could be considered as risk factors for SLE. In addition, the polymorphisms at IL-10 (-1082 G/G and AA) may play a role in SLE susceptibility in Egyptian patients. Larger prospective studies are needed to confirm our findings.

Association of the interleukin-6 polymorphisms with systemic lupus erythematosus: a meta-analysis

BACKGROUND

Interleukin (IL)-6, an important proinflammatory cytokine, plays a potential pathological role in systemic lupus erythematosus (SLE). Studies on the relationship of IL-6 gene polymorphisms with SLE are inconclusive. The aim of this study was to estimate the relationship more precisely.

METHODS

The databases of PubMed and Web of Science updated to 30 August 2014 were retrieved. Meta-analysis was conducted using allelic contrast, dominant, recessive and homozygote contrast models. Fifteen studies were included in this study and ethnicity-specific meta-analysis was performed on European, Iranian and Asian populations.

RESULTS

Analysis for the IL-6-174 G/C polymorphism under all models except the homozygote contrast model indicated an association in the overall population (allelic contrast model: odds ratio (OR) 1.428, 95% confidence interval (CI) 1.124-1.812, dominant model: OR 1.382, 95% CI 1.037-1.842, recessive model: OR 1.610, 95% CI 1.158-2.240, homozygote contrast model: OR 1.759, 95% CI 0.989-3.127), as well as in European individuals under all four genetic models (allelic contrast model: OR 1.557, 95% CI 1.155-2.098, dominant model: OR 1.699, 95% CI 1.203-2.400, recessive model: OR 1.506, 95% CI 1.176-1.930, homozygote contrast model: OR 2.118, 95% CI 1.103-4.065). Analysis for the IL-6-572 G/C polymorphism indicated significant association in overall ethnicities under the recessive model (OR 1.491, 95% CI 1.104-2.014), but not under other models or in Asian individuals. In addition, significant association between the IL-6-174 G/C polymorphism and discoid skin lesions and antinuclear antibodies (ANAs) were found under the allelic contrast model and recessive model, respectively (discoid skin lesions: OR 2.271, 95% CI 1.053-4.895; ANAs: OR 2.244, 95% CI 1.141-4.416).

CONCLUSION

This meta-analysis provides evidence of the association between the IL-6 polymorphism and the risk of SLE, hinting that the IL-6-174 G/C and IL-6-572 G/C polymorphisms may play a role in SLE susceptibility.

Meta-analysis of the correlation between IL-6 -174 G/C polymorphism and polycystic ovarian syndrome

AIM

The correlation between interleukin-6 (IL-6) gene polymorphism and polycystic ovary syndrome (PCOS) has been reported, but the conclusions are controversial. The present study was aimed to evaluate the association between IL-6 -174 G/C polymorphism and susceptibility of PCOS by meta-analysis.

MATERIAL AND METHODS

A systematic search on Medline, Embase, CNKI, Wanfang Data and VIP databases containing Chinese and English studies was conducted electronically using specific eligibility criteria. Meta-analysis was performed using Review Manager 5.2 software after Hardy-Weinberg equilibrium test. Effect sizes of odds ratio and 95% confidence interval (CI) were calculated and combined appropriately. To verify the reliability of the results, subgroup analyses and sensitivity analyses were performed.

RESULTS

Four selected studies containing 351 cases and 464 control participants were included. The pooled odds ratio between IL-6 -174 G/C polymorphism and susceptibility of PCOS under allele (C/G), dominant (CC+GC/GG) and recessive (CC/GG+GC) models were 0.63 (95%CI, 0.41-0.96), 0.53 (95%CI, 0.26-1.08) and 0.67 (95%CI, 0.39-1.16), respectively. The result under allele model was unstable in sensitivity analysis. Subgroup analysis showed that the correlation between IL-6 -174 G/C polymorphism and susceptibility of PCOS was not statistically significant in the studies that conformed to the Hardy-Weinberg equilibrium.

CONCLUSION

IL-6 -174 G/C polymorphism may be not related to susceptibility of PCOS. Nevertheless, further studies with large samples and studies considering other single-nucleotide polymorphisms of the IL-6 gene are needed to confirm our findings.

Association of STAT4 polymorphism with severe renal insufficiency in lupus nephritis

Lupus nephritis is a cause of significant morbidity in systemic lupus erythematosus (SLE) and its genetic background has not been completely clarified. The aim of this investigation was to analyze single nucleotide polymorphisms (SNPs) for association with lupus nephritis, its severe form proliferative nephritis and renal outcome, in two Swedish cohorts. Cohort I (n = 567 SLE cases, n = 512 controls) was previously genotyped for 5676 SNPs and cohort II (n = 145 SLE cases, n = 619 controls) was genotyped for SNPs in STAT4, IRF5, TNIP1 and BLK. Case-control and case-only association analyses for patients with lupus nephritis, proliferative nephritis and severe renal insufficiency were performed. In the case-control analysis of cohort I, four highly linked SNPs in STAT4 were associated with lupus nephritis with genome wide significance with p = 3.7 × 10(-9), OR 2.20 for the best SNP rs11889341. Strong signals of association between IRF5 and an HLA-DR3 SNP marker were also detected in the lupus nephritis case versus healthy control analysis (p <0.0001). An additional six genes showed an association with lupus nephritis with p <0.001 (PMS2, TNIP1, CARD11, ITGAM, BLK and IRAK1). In the case-only meta-analysis of the two cohorts, the STAT4 SNP rs7582694 was associated with severe renal insufficiency with p = 1.6 × 10(-3) and OR 2.22. We conclude that genetic variations in STAT4 predispose to lupus nephritis and a worse outcome with severe renal insufficiency.

The role of cytokines in the pathogenesis of systemic lupus erythematosus - from bench to bedside

The pathogenesis of systemic lupus erythematosus (SLE) entails a complex interaction between the different arms of the immune system. While autoantibodies production and immune complex deposition are cornered as hallmark features of SLE, there is growing evidence to propose the pathogenic role of cytokines in this disease. Examples of these cytokines include BLys, interleukin-6, interleukin-17, interleukin-18, type I interferons and tumour necrosis factor alpha. These cytokines all assume pivotal functions to orchestrate the differentiation, maturation and activation of various cell types, which would mediate local inflammatory process and tissue injury. The knowledge on these cytokines not only fosters our understanding of the disease, but also provides insights in devising biomarkers and targeted therapies. In this review, we focus on cytokines which have substantial pathogenic significance and also highlight the possible clinical applications of these cytokines.

Role of the promoter polymorphism IL-6 -174G/C in dermatomyositis and systemic lupus erythematosus

The promoter polymorphism -174G/C within the interleukin-6 gene (IL-6) has been reported to have a functional importance through the modulation of IL-6 gene expression in vitro and in vivo. IL-6 is thought to play an important role in autoimmune diseases and the effect of its receptor inhibitor-tocilizumab-has been recently studied. The aim of this case-control study was to investigate the association between the interleukin-6 -174G/C single nucleotide polymorphism and the susceptibility to dermatomyositis (DM) and systemic lupus erythematosus (SLE) in Bulgarian patients. Altogether, 87 patients-52 with SLE and 35 with DM-as well as 80 unrelated healthy controls were included in this study. All of them were analyzed by restriction fragment length polymorphism analysis (RFLP). The GG genotype and the G allele appeared to be associated with SLE, especially in women. None of the genotypes showed an association with DM. However, the G allele appeared to be associated with muscle weakness and it is a risk factor for elevated muscle enzymes. Our results indicate that IL-6 -174G/C polymorphism might be associated with the susceptibility to SLE especially in women. Although it is not associated with DM, it seems that IL-6 -174G/C polymorphism could modulate some clinical features in the autoimmune myopathies.

TGF-β1 limits the onset of innate lung inflammation by promoting mast cell-derived IL-6

TGF-β1 is an important suppressive mediator of inflammation, but it can also drive fibrosis and remodeling in the lung. In response to intratracheal LPS, neutrophils migrate into the lung, and TGF-β1 was suggested to protect against the ensuing injury. However, the mechanisms for this protective role remain unknown. Using a model of acute lung injury, we demonstrate that TGF-β1 decreases neutrophil numbers during the onset of injury. This was due to increased apoptosis rather than reduced migration. We demonstrate that TGF-β1 does not directly regulate neutrophil apoptosis but instead functions through IL-6 to promote neutrophil clearance. rIL-6 is sufficient to promote neutrophil apoptosis and reduce neutrophilia in bronchoalveolar lavage fluid, while IL-6 increases rapidly following LPS-induced injury. Mast cells are a critical source of IL-6, because mast cell-deficient mice exhibit increased neutrophil numbers that are reduced by reconstitution with wild-type, but not IL-6(-/-), mast cells. Although IL-6 diminishes neutrophilia in mast cell-deficient mice, TGF-β1 is ineffective, suggesting that these effects were mast cell dependent. Taken together, our findings establish a novel pathway through which TGF-β1, likely derived from resident regulatory T cells, controls the severity and magnitude of early innate inflammation by promoting IL-6 from mast cells.

Glucocorticoid regulates interleukin-37 in systemic lupus erythematosus

The aim of this study was to research the expression of IL-37 in systemic lupus erythematosus (SLE) patients and the effect of glucocorticoid on IL-37. Thirty newly diagnosed severe SLE patients receiving prednisone 1 mg/kg/day for 14 consecutive days and 30 healthy subjects were enrolled into this study. The plasma levels of IL-37 and other cytokines were detected by ELISA and the relative mRNA amounts of IL-37 and other cytokines were detected by RT-PCR. The plasma levels of IL-37, IL-18, IL-18BP, IFN-γ, and IL-6 in SLE patients increased significantly compared with healthy controls (p<0.05). The relative amount of IL-37 mRNA increased by 2.45-fold in pre-treatment SLE patients compared with controls (p<0.05). Plasma concentrations of IL-37 correlated with IL-18, IL-18BP, IFN-γ, IL-6 and SLEDAI score in both pre-treatment and post-treatment SLE patients. The plasma levels of IL-37 decreased significantly after treatment of glucocorticoid. The relative amount of IL-37 mRNA decreased by 24.5 % in post-treatment SLE patients compared with pre-treatment ones (p<0.01). In conclusion, IL-37 is upregulated in active SLE patients. IL-37 is correlated with pro-inflammatory cytokines and SLEDAI. Glucocorticoid can downregulate the expression of IL-37 and other cytokines in SLE patients.

Association between -174 interleukin-6 gene polymorphism and biological response to rituximab in several systemic autoimmune diseases

Rituximab has become a pivotal treatment for systemic autoimmune diseases. The aim of this study was to determine whether the genetic variant -174 IL-6 contributes to differences in the response to rituximab in patients with systemic autoimmune diseases, including systemic lupus erythematosus (SLE), inflammatory myopathies, anti-neutrophil cytoplasmic antibody-mediated vasculitis, systemic sclerosis, Sjöegren's syndrome, rheumatoid arthritis, and autoimmune hemolytic anemia. DNA samples from 144 Spanish patients with different systemic autoimmune diseases receiving rituximab were genotyped for -174 IL-6 (rs1800795) gene polymorphism using the TaqMan(®) allelic discrimination technology. Six months after the first infusion with rituximab, we evaluated the response to the drug: 60.4% of the patients showed a complete response, partial 27.8%, and 11.8% did not respond to the treatment. The CC genotype frequency was significantly increased in nonresponders with respect to responders (23.5% vs. 7.1%, respectively; p=0.049; odds ratio (OR)=4.03, 95% confidence intervals (CI) 0.78-16.97). According to the genotype distribution, rituximab was effective in 69.2% of the CC carriers, 91.9% of the CG carriers, and 88.4% of the GG carriers. A similar trend was observed when SLE patients were analyzed separately (27.3% carried CC homozygosis in nonresponders and 6.9% in responders; p=0.066; OR=5.10, 95% CI 0.65-31.73). Rituximab was effective in 62.5% of the CC carriers, 88.9% of the GC carriers, and 90% of the GG carriers. These results suggest that -174 IL-6 (rs1800795) gene polymorphism plays a role in the response to rituximab in systemic autoimmune diseases. Validation of these findings in independent cohorts is warranted.

Role of TWEAK in lupus nephritis: a bench-to-bedside review

There is significant unmet need in the treatment of lupus nephritis (LN) patients. In this review, we highlight the role of the TWEAK/Fn14 pathway in mediating key pathologic processes underlying LN involving both glomerular and tubular injury, and thus the potential for renal protection via blockade of this pathway. The specific pathological mechanisms of TWEAK - namely promoting inflammation, renal cell proliferation and apoptosis, vascular activation and fibrosis - are described, with supporting data from animal models and in vitro systems. Furthermore, we detail the translational relevance of these mechanisms to clinical readouts in human LN. We present the opportunity for an anti-TWEAK therapeutic as a renal protective agent to improve efficacy relative to current standard of care treatments hopefully without increased safety risk, and highlight a phase II trial with BIIB023, an anti-TWEAK neutralizing antibody, designed to assess efficacy in LN patients. Taken together, targeting the TWEAK/Fn14 axis represents a potential new therapeutic paradigm for achieving renal protection in LN patients.

Treatment of systemic lupus erythematosus: new advances in targeted therapy

Treatment for systemic lupus erythematosus (SLE) has traditionally been restricted to broad-based immunosuppression, with glucocorticoids being central to care. Recent insights into lupus pathogenesis promise new, selective therapies with more favorable side effect profiles. The best example of this is belimumab, which targets the B cell cytokine BLyS and has now received Food and Drug Administration (FDA) approval for its use in SLE. Strategies targeting other cytokines, such as interleukin 6 (IL-6) and interferon (IFN)-α, are also on the horizon. Blockade of costimulatory interactions between immune cells offers another opportunity for therapeutic intervention, as do small molecule inhibitors that interfere with cell signaling pathways. We review here the current strategies for SLE treatment, with particular focus on therapies now in active pharmaceutical development. We will also discuss new understandings in lupus pathogenesis that may lead to future advances in therapy.

The association between interleukin-6 polymorphisms and systemic lupus erythematosus: a meta-analysis

The aim of this study was to determine whether the functional interleukin-6 (IL-6) promoter -174 G/C and -572 G/C polymorphisms confer susceptibility to systemic lupus erythematosus (SLE) in ethnically different populations. Meta-analysis was conducted on the associations between the IL-6 polymorphisms and SLE using; 1) allele contrast, 2) the recessive model, 3) the dominant model, and 4) the additive model. A total of 11 studies were considered in this study, and ethnicity-specific meta-analysis was performed on European and Asian populations. Meta-analysis of the IL-6 -174 G/C polymorphism showed an association between SLE and the IL-6 -174 G allele in all study subjects (odds ratio (OR) = 1.344, 95% confidence interval (CI) = 1.052-1.718, p = 0.018). Furthermore, stratification by ethnicity indicated an association between the IL-6 -174 G allele and SLE in Europeans (OR = 1.264, 95% CI = 1.037-1.541, p = 0.020). Meta-analysis of the IL-6 -572 G/C polymorphism revealed that an association was found between SLE and the IL-6 -572 G/C polymorphism using the recessive model, but ethnicity-specific meta-analysis revealed no association between SLE and the IL-6 -572 G/C polymorphism in Asians. In conclusion, this meta-analysis demonstrates that the IL-6 -174 G/C polymorphism may confer susceptibility to SLE in Europeans, but that the IL-6 -572 G/C polymorphism is not associated with susceptibility to SLE in Asians.

Genetic risk factors of systemic lupus erythematosus in the Malaysian population: a minireview

SLE is an autoimmune disease that is not uncommon in Malaysia. In contrast to Malays and Indians, the Chinese seem to be most affected. SLE is characterized by deficiency of body's immune response that leads to production of autoantibodies and failure of immune complex clearance. This minireview attempts to summarize the association of several candidate genes with risk for SLE in the Malaysian population and discuss the genetic heterogeneity that exists locally in Asians and in comparison with SLE in Caucasians. Several groups of researchers have been actively investigating genes that are associated with SLE susceptibility in the Malaysian population by screening possible reported candidate genes across the SLE patients and healthy controls. These candidate genes include MHC genes and genes encoding complement components, TNF, FcγR, T-cell receptors, and interleukins. However, most of the polymorphisms investigated in these genes did not show significant associations with susceptibility to SLE in the Malaysian scenario, except for those occurring in MHC genes and genes coding for TNF-α, IL-1β, IL-1RN, and IL-6.