Extended haplotype analysis reveals an association of TNF polymorphisms with susceptibility to systemic lupus erythematosus beyond HLA‐DR3

Lessons for lupus from tumour necrosis factor blockade

Systemic lupus erythematosus (SLE) is a systemic non-organ specific autoimmune disease associated with multiple autoantibodies targeting autoantigens from the nucleus. Given the complex pathophysiology of SLE and the role of TNF alpha in that disease, modulation of TNF alpha (in SLE or non-SLE patients) using TNF blockers could either be detrimental or beneficial in some patients. In this review we will focus on lupus autoantibodies and clinical manifestations after TNF blockade in SLE patients and conversely on drug-induced-SLE in non-SLE patients. Some hypotheses regarding the mechanism of induction of autoantibodies in RA patients treated with TNF blockers are proposed.

TNF-308 G/A polymorphism and risk of systemic lupus erythematosus in the Polish population

OBJECTIVES

Numerous studies have been performed with TNF-α-308 G/A (rs1800629) single nuclear polymorphism (SNP) to evaluate the risk of SLE in various ethnicities. However, the significance of TNF-α-308 G/A in both clinical and laboratory studies of the disease remains unclear.

METHODS

Using a high-resolution melting curve analysis, we assessed the prevalence of TNF-α-308 G/A SNP in SLE patients (n = 262) and controls (n = 528) in a Polish population. We also assessed the contribution of this SNP to various clinical symptoms and the presence of autoantibodies in SLE patients.

RESULTS

The p-value obtained using a χ(2) test for the trend of TNF-α-308 G/A was statistically significant (ptrend = 0.0297). However, using logistic regression analysis for the presence of the HLA-DRB1*03:01 haplotype, we observed that the TNF-α-308 G/A SNP may be the DRB1*03:01-dependent risk factor of SLE in the Polish population. There was a significant contribution of TNF-α-308 A/A and A/G genotypes to arthritis OR = [2.692 (1.503-4.822, p = 0.0007, pcorr = 0.0119)] as well as renal SLE manifestation OR = [2.632 (1.575-4.397, p = 0.0002, pcorr = 0.0034)]. There was a significant association between TNF-α-308 A/A and A/G genotypes and the presence of anti-Ro antibodies (Ab) OR = 3.375(1.711-6.658, p = 0.0003, pcorr = 0.0051). However, the logistic regression analysis revealed that only renal manifestations and the presence of anti-anti-Ro antibodies remained significant after adjustment to the presence of the HLA-DRB1*03:01 haplotype.

CONCLUSION

Our studies indicate that the TNF-α-308 G/A polymorphism may be a DRB1*03:01 haplotype-dependent genetic risk factor for SLE. However, this SNP was independently associated with renal manifestations and production of anti-Ro Ab.

Role of MHC-linked susceptibility genes in the pathogenesis of human and murine lupus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies against nuclear antigens and a systemic inflammation that can damage a broad spectrum of organs. SLE patients suffer from a wide variety of symptoms, which can affect virtually almost any tissue. As lupus is difficult to diagnose, the worldwide prevalence of SLE can only be roughly estimated to range from 10 and 200 cases per 100,000 individuals with dramatic differences depending on gender, ethnicity, and location. Although the treatment of this disease has been significantly ameliorated by new therapies, improved conventional drug therapy options, and a trained expert eye, the underlying pathogenesis of lupus still remain widely unknown. The complex etiology reflects the complex genetic background of the disease, which is also not well understood yet. However, in the past few years advances in lupus genetics have been made, notably with the publication of genome-wide association studies (GWAS) in humans and the identification of susceptibility genes and loci in mice. This paper reviews the role of MHC-linked susceptibility genes in the pathogenesis of systemic lupus erythematosus.

The role of Tumor Necrosis Factor-alpha (TNF-α) in the pathogenesis of systemic lupus erythematosus

The Tumor Necrosis Factor-alpha (TNF-α) is a pleiotropic cytokine that produces different stimuli in various physiological and pathological conditions. TNF-α contributes importantly to the development of T cells, B cells, and dendritic cells. However, TNF-α is also a potent inflammatory mediator and apoptosis inducer. The significance of the TNF-α involvement in the pathogenesis of systemic lupus erythematosus (SLE) remains controversial. From the genetic standpoint, a number of studies suggest that the TNF-α gene polymorphism is involved in the susceptibility of SLE. Moreover, there is a close association between the TNF-α gene expression and clinical manifestations. In addition, the increased serum level of TNF-α is observed in SLE patients and associated with disease activity and certain systemic manifestations. Treatment with anti-TNF agents is, however, controversial in SLE since induction of antinuclear antibodies, anti-dsDNA, anticardiolipin antibodies, and cases of drug-induced lupus have been observed in rheumatoid arthritis patients. In this context, this study reviewed the importance of TNF-α in the pathogenesis of SLE.

Association of TNF-α promoter-308 A/G polymorphism with susceptibility to systemic lupus erythematosus: a meta-analysis

Published data on the association between tumor necrosis factor-alpha (TNF-α) promoter-308 A/G polymorphism and systemic lupus erythematosus (SLE) risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 28 studies including 2,992 cases and 4,326 controls (5,924 cases and 8,484 controls in A versus G comparison) were involved in this meta-analysis. Meta-analysis was performed for genotypes A/A (recessive effect), A/A+A/G (dominant effect), and A allele in fixed or random effects models. In addition, we also performed a "model-free" analysis by considering the G/G genotype as the reference and estimated the OR for the A/A versus G/G and A/G versus G/G genotype. Overall, an association of TNF-α promoter-308 A/G polymorphism with SLE was found (A versus G: OR = 1.686, 95% CI = 1.400-2.032, P < 0.001; A/A versus A/G+G/G: OR = 3.043, 95% CI = 2.185-4.238, P < 0.001; A/A+A/G versus G/G: OR = 1.822, 95% CI = 1.379-2.407, P < 0.001; A/A versus G/G: OR = 3.686, 95% CI = 2.628-5.172, P < 0.001; A/G versus G/G: OR = 1.691, 95% CI = 1.291-2.215, P < 0.001). However, stratification by ethnicity indicated that the risk A allele was not associated with SLE in Asian (A versus G: OR = 1.207, 95% CI = 0.856-1.702, P = 0.283) and African population (A versus G: OR = 1.225, 95% CI = 0.597-2.516, P = 0.580). In summary, this meta-analysis indicated that TNF-α promoter-308-A/G polymorphism is associated with susceptibility to SLE.

IL-10 and TNFalpha genotypes in SLE

The production of two regulators of the inflammatory response, interleukin 10 (IL-10) and tumor necrosis factor α (TNFα), has been found to be deeply deregulated in SLE patients, suggesting that these cytokines may be involved in the pathogenesis of the disease. Genetic polymorphisms at the promoter regions of IL-10 and TNFα genes have been associated with different constitutive and induced cytokine production. Given that individual steady-state levels of these molecules may deviate an initial immune response towards different forms of lymphocyte activation, functional genetic variants in their promoters could influence the development of SLE. The present review summarizes the information previously reported about the involvement of IL-10 and TNFα genetic variants on SLE appearance, clinical phenotype, and outcome. We show that, in spite of the heterogeneity of the populations studied, the existing knowledge points towards a relevant role of IL-10 and TNFα genotypes in SLE.

Meta-analysis of TNF-α promoter -308A/G polymorphism and SLE susceptibility in Asian populations

The aim of this study was to summarize results on the association of tumor necrosis factor-α (TNF-α) promoter -308A/G polymorphism with systemic lupus erythematosus (SLE) susceptibility in Asian populations by using the meta-analysis. We searched all the publications about the association between TNF-α promoter -308A/G polymorphism and SLE in Asian populations from PubMed, Elsevier Science Direct, Chinese Biomedical Literature Database (CBM), Chinese National Knowledge Infrastructure (CNKI), and Wanfang (Chinese). Meta-analysis was performed for genotypes AA versus GG, GA versus GG, AA versus GG + GA, GA + AA versus GG, and A allele versus G allele in a fixed/random effect model. A total of 12 studies (1017 cases and 1086 controls) were included in the current meta-analysis (Chinese, Japanese, and Thai). When all groups were pooled, a significant association of A allele and increased SLE risk was found (OR = 1.44, 95%CI = 1.04-2.01, P = 0.03). When analyses were restricted to more ethnically homogeneous populations, similar result was found in Chinese population (OR = 1.59, 95%CI = 1.12-2.26, P = 0.009). But the association between TNF-α promoter -308 polymorphism and SLE was not observed when examining the contrast of G/A + A/A versus G/G, A/A versus A/G + G/G, A/A versus G/G, and G/A versus G/G. This meta-analysis demonstrates the association between TNF-α promoter -308A/G polymorphism and SLE in Asian populations, especially in Chinese population.

Tumor necrosis factor (TNF) and lymphotoxin-alpha (LTA) polymorphisms and risk of non-Hodgkin lymphoma in the InterLymph Consortium

In an International Lymphoma Epidemiology Consortium pooled analysis, polymorphisms in 2 immune-system-related genes, tumor necrosis factor (TNF) and interleukin-10 (IL10), were associated with non-Hodgkin lymphoma (NHL) risk. Here, 8,847 participants were added to previous data (patients diagnosed from 1989 to 2005 in 14 case-control studies; 7,999 cases, 8,452 controls) for testing of polymorphisms in the TNF -308G>A (rs1800629), lymphotoxin-alpha (LTA) 252A>G (rs909253), IL10 -3575T>A (rs1800890, rs1800896), and nucleotide-binding oligomerization domain containing 2 (NOD2) 3020insC (rs2066847) genes. Odds ratios were estimated for non-Hispanic whites and several ethnic subgroups using 2-sided tests. Consistent with previous findings, odds ratios were increased for "new" participant TNF -308A carriers (NHL: per-allele odds ratio (OR(allelic)) = 1.10, P(trend) = 0.001; diffuse large B-cell lymphoma (DLBCL): OR(allelic) = 1.23, P(trend) = 0.004). In the combined population, odds ratios were increased for TNF -308A carriers (NHL: OR(allelic) = 1.13, P(trend) = 0.0001; DLBCL: OR(allelic) = 1.25, P(trend) = 3.7 x 10(-6); marginal zone lymphoma: OR(allelic) = 1.35, P(trend) = 0.004) and LTA 252G carriers (DLBCL: OR(allelic) = 1.12, P(trend) = 0.006; mycosis fungoides: OR(allelic) = 1.44, P(trend) = 0.015). The LTA 252A>G/TNF -308G>A haplotype containing the LTA/TNF variant alleles was strongly associated with DLBCL (P = 2.9 x 10(-8)). Results suggested associations between IL10 -3575T>A and DLBCL (P(trend) = 0.02) and IL10 -1082A>G and mantle cell lymphoma (P(trend) = 0.04). These findings strengthen previous results for DLBCL and the LTA 252A>G/TNF -308A locus and provide robust evidence that these TNF/LTA gene variants, or others in linkage disequilibrium, are involved in NHL etiology.

Correlation of ESR, C3, C4, anti-DNA and lupus activity based on British Isles Lupus Assessment Group Index in patients of rheumatology clinic

This study aimed to determine the correlation between of ESR, C3, C4, anti-DNA, and lupus activity and also the construct and criterion validity of the British Isles Lupus Assessment Group (BILAG) index for assessing disease activity in systemic lupus erythematosus (SLE). Patients with SLE were recruited into a cross-sectional study. Data were analyzed for estimating of SLE disease activity [scores on the BILAG index and Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K)]. Overall BILAG scores were determined by the highest score achieved in any of the individual systems in the respective index. Erythrocyte sedimentation rates (ESRs), C3 levels, C4 levels, anti-double-stranded DNA (anti-dsDNA) levels, and SLEDAI-2K scores were used in the analysis of construct validity. Statistical analyses were performed using ordinal logistic regression for construct validity. Of the 100 patients with SLE, 90% were women. Their mean ± SD age was 31.1 ± 9.8 years. Increasing overall scores on the BILAG index were associated with increasing ESRs, decreasing C3 levels, decreasing C4 levels, elevated anti-dsDNA levels, and increasing SLEDAI-2K scores (all P < 0.01). These findings show that the ESR, C3, C4, and anti-DNA should be used in the evaluation and management of patients with SLE. Also the results show that the BILAG index has construct validity.

Molecular analysis of HLA-DRB1 allelic associations with systemic lupus erythematous and lupus nephritis in Taiwan

To evaluate the association of human leukocyte antigen (HLA)–DRB1 alleles with systemic lupus erythematosus (SLE) and lupus nephritis (LN) in the Taiwanese population, and to investigate the possible association of HLA-DRB1 alleles with disease severity in LN. HLA-DRB1 alleles were studied in 105 SLE patients (82 patients with LN, 23 patients without LN) and 855 healthy controls by polymerase chain reaction and sequence-based typing assays. The frequency of the HLA class II alleles DRB1*0301 (Odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.31–3.10, Pc = 0.02) and DRB1*1501 (OR = 2.06, 95% CI = 1.36–3.13, Pc = 0.01) were both increased in SLE patients, compared to healthy controls. The frequency of DRB1*1202 was significantly lower in LN patients than in SLE patients without nephritis (OR = 0.23, 95% CI = 0.09–0.57, Pc = 0.01). No specific allele was significantly associated with an increased or decreased risk for severity of LN in this sample. In Taiwanese people, the DRB1*0301 and DRB1*1501 alleles are significant risk factors for SLE, while the DRB1*1202 allele is protective for LN.

British Isles Lupus Assessment Group 2004 index is valid for assessment of disease activity in systemic lupus erythematosus

Objective

To determine the construct and criterion validity of the British Isles Lupus Assessment Group 2004 (BILAG-2004) index for assessing disease activity in systemic lupus erythematosus (SLE).

Methods

Patients with SLE were recruited into a multicenter cross-sectional study. Data on SLE disease activity (scores on the BILAG-2004 index, Classic BILAG index, and Systemic Lupus Erythematosus Disease Activity Index 2000 [SLEDAI-2K]), investigations, and therapy were collected. Overall BILAG-2004 and overall Classic BILAG scores were determined by the highest score achieved in any of the individual systems in the respective index. Erythrocyte sedimentation rates (ESRs), C3 levels, C4 levels, anti–double-stranded DNA (anti-dsDNA) levels, and SLEDAI-2K scores were used in the analysis of construct validity, and increase in therapy was used as the criterion for active disease in the analysis of criterion validity. Statistical analyses were performed using ordinal logistic regression for construct validity and logistic regression for criterion validity. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

Results

Of the 369 patients with SLE, 92.7% were women, 59.9% were white, 18.4% were Afro-Caribbean and 18.4% were South Asian. Their mean ± SD age was 41.6 ± 13.2 years and mean disease duration was 8.8 ± 7.7 years. More than 1 assessment was obtained on 88.6% of the patients, and a total of 1,510 assessments were obtained. Increasing overall scores on the BILAG-2004 index were associated with increasing ESRs, decreasing C3 levels, decreasing C4 levels, elevated anti-dsDNA levels, and increasing SLEDAI-2K scores (all P < 0.01). Increase in therapy was observed more frequently in patients with overall BILAG-2004 scores reflecting higher disease activity. Scores indicating active disease (overall BILAG-2004 scores of A and B) were significantly associated with increase in therapy (odds ratio [OR] 19.3, P < 0.01). The BILAG-2004 and Classic BILAG indices had comparable sensitivity, specificity, PPV, and NPV.

Conclusion

These findings show that the BILAG-2004 index has construct and criterion validity.

Expression and function of IL-10R in mononuclear cells from patients with systemic lupus erythematosus

OBJECTIVE

To assess the expression and function of the receptor for interleukin-10 (IL-10R) in immune cells from patients with systemic lupus erythematosus (SLE).

METHODS

We assessed the expression and function of IL-10R in peripheral blood mononuclear cells (PBMCs) from 19 SLE patients and 15 healthy controls. The expression of IL-10R was assessed by flow cytometry, and the function of this receptor was determined by analysing both the activation of Jak-1, Tyk-2, Stat-1, and Stat-3 (Western blot) and the induction of gene expression (cDNA array test of 242 genes of cytokines, apoptosis and intracellular signalling) upon stimulation with IL-10.

RESULTS

We found similar levels of IL-10R expression in SLE patients and controls. In addition, variable levels of Jak-1, Tyk-2, Stat-1, and Stat-3 activation were induced by IL-10 in PBMCs from SLE patients and controls, with no significant differences in protein phosphorylation or kinetics of activation. However, clear-cut differences in the gene expression induced through IL-10R were observed in SLE patients and controls, mainly in the genes involved in apoptosis and those encoding for cytokines and their receptors.

CONCLUSIONS

Our data suggest that despite normal levels of IL-10R expression, and an apparent lack of abnormalities in the intracellular signals induced through this receptor, immune cells from SLE patients exhibit an aberrant pattern of gene expression induced through the IL-10R.