Systemic Sclerosis Susceptibility Research Articles

The Role of IRF8 Polymorphisms in Systemic Sclerosis Development and Pathogenesis

The Role of IRF8 Polymorphisms in Systemic Sclerosis Development and Pathogenesis

Contribution of HLA and KIR Alleles to Systemic Sclerosis Susceptibility and Immunological and Clinical Disease Subtypes.

Systemic sclerosis (SSc) is an autoinflammatory, fibrotic condition of unknown aetiology. The presence of detectable autoantibodies against diverse nuclear antigens, as well as strong HLA associations with disease, suggest autoimmune involvement, however the links between endogenous and exogenous risk factors and SSc pathology remain undetermined. We have conducted a genetic analysis of HLA inheritance in two independent and meta-analysed cohorts of 1,465 SSc cases and 13,273 controls, including stratified association analyses in clinical and autoantibody positive subgroups of disease. Additionally, we have used patient genotypes to impute gene dosages across the KIR locus, encoding paired activating and inhibitory lymphocyte receptors for Class I HLA ligands, to conduct the largest analysis of KIR-HLA epistatic interactions in SSc to date. We confirm previous Class II HLA associations with SSc risk and report a new Class I association with haplotype HLA-B*44:03-HLA-C*16:01 at genome-wide significance (GWS). We further report statistically significant HLA associations with clinical and serological subtypes of disease through direct case-case comparison, and report a new association of HLA-DRB1*15:01, previously shown to bind topoisomerase-1 derived peptides, with anti-topoisomerase (ATA) positive disease. Finally, we identify genetic epistasis between KIRs and HLA class I ligands, suggesting genetic modulation of lymphocyte activation may further contribute to an individual’s underlying disease risk. Taken together, these findings support future functional investigation into endogenous immunological and environmental stimuli for disrupted immune tolerance in SSc.

Genetic Association between TNFA Polymorphisms (rs1799964 and rs361525) and Susceptibility to Cancer in Systemic Sclerosis.

Tumor necrosis factor (TNF)-α is a proinflammatory cytokine that plays an important role in the pathogenesis of autoimmune diseases. The aim of the study was to establish an association between TNF-α promoter variability and systemic sclerosis (SSc). The study included 43 SSc patients and 74 controls. Four single nucleotide polymorphisms (rs361525, rs1800629, rs1799724, and rs1799964) located at the promoter of the TNFA gene were genotyped using commercially available TaqMan allelic discrimination assays with real-time PCR. The rs1799724 allele was associated with an increased SSc susceptibility (p = 0.028). In turn, none of the polymorphisms studied were related to the clinical and laboratory parameters of SSc patients, except for a higher prevalence of anti-Ro52 antibodies in the AG rs1800629 genotype in comparison to GG carriers (p = 0.04). Three of four cancer patients had both CT rs1799964 and AG rs361525 genotypes; thus, both of them were related to the increased risk of cancer, as compared to the TT (p = 0.03) and GG carriers (p = 0.0003), respectively. The TNFA C rs1799724 variant is associated with an increased risk of SSc, while the CT rs1799964 and AG rs361525 genotypes might enhance cancer susceptibility in SSc patients, although large observational and experimental studies are needed to verify the above hypothesis.

Preliminary observations on ANGPT1 and ANGPT2 polymorphisms in systemic sclerosis: ANGPT2 rs2442598 and rs3739390 are associated with disease susceptibility and diffuse disease subtype.

Angiopoietin-1 (Ang-1) and -2 (Ang-2) concentrations were found to be associated with systemic sclerosis (SSc). We explored whether single nucleotide polymorphisms of Ang-1 (ANGPT1) and Ang-2 (ANGPT2) genes can predict SSc susceptibility in Polish Caucasian patients. Genotyping by reverse transcriptase–polymerase chain reaction and Sanger sequencing was performed in 48 patients with SSc and 38 controls. Individuals with the CC genotype of ANGPT2 rs2442598 were 3.29-fold more likely to develop SSc (odds ratio [OR], 3.288; 95% CI, 1.212–8.915; P = 0.02) compared with those carrying the CT variant. Subgroup analysis revealed that the G allele, CG, and CG+GG genotypes of ANGPT2 rs3739390 were associated with a 9-fold higher risk to develop a diffuse form of the disease compared with the C allele or CC genotype (OR, 9.00; 95% CI, 2.102–38.519; P = 0.002 and OR, 9.00; 95% CI, 1.112–72.824; P = 0.03, respectively) and patients carrying the CG variant presented with higher serum Ang-2 levels than those carrying the CC variant (P = 0.001). On the contrary, the likelihood of a diffuse disease subtype was 8.77-fold lower for the TT+AT than for the AA genotype of ANGPT1 rs2507800 (OR, 0.114; 95% CI, 0.014–0.932; P= 0.04). The C allele of ANGPT2 rs3739390 was associated with a 4.83-fold lower risk of digital ulcers (OR, 4.833; 95% CI, 1.089–21.437; P= 0.03). We concluded for the first time in the literature that the ANGPT2 rs2442598 polymorphism might represent a susceptibility locus for SSc, whereas the ANGPT2 rs3739390 and ANGPT1 rs2507800 variants may affect the disease profile.

Genetic variants in LGALS3 are related to lower galectin-3 serum levels and clinical outcomes in systemic sclerosis patients: A case-control study

Introduction Systemic sclerosis (SSc) is a rare complex disease characterized by vascular damage, autoimmunity, and extensive skin and internal organs fibrosis. Galectin-3 (Gal-3) is encoded by gene LGALS3 (Lectin, Galactoside-Binding, Soluble, 3; 14q22.3) and it has been reported to play a central role in self-tolerance, inflammation, and fibrosis. Objective To investigate associations among LGALS3 single nucleotide polymorphisms (SNPs) and serum levels Gal-3 and SSc susceptibility and their clinical features. Methods A case-control study with 88 patients and 151 matched controls was performed. LGALS3 variants were analyzed by the TaqMan real-time polymerase chain reaction (PCR) system whereas Gal-3 serum levels were measured by sandwich enzyme linked immunosorbent assay (ELISA). Associations among genotypes, clinical features, and Gal-3 levels were performed by univariable and multivariable analysis through statistical packages. Results The LGALS3 rs4652 A/C genotype was more frequent in SSc patients than controls according to overdominant model [OR 1.89 (CI 95% 1.01 − 3.52); p = .046]. Also, LGALS3 rs4652 C/C polymorphic genotype was associated with lower patient Gal-3 levels (p = .03) and control group (p = 0.005), as noted by generalized linear model (GLM). The LGALS3 rs1009977 G/T controls showed higher Gal-3 levels than wild-type and polymorphic genotypes (p = .03); however, in SSc patients, no difference was found. None of the LGALS3 SNPs or Gal-3 levels was associated with clinical manifestations in SSc patients. Considering only the SSc group, GLM analysis pointed LGALS3 rs4652 and rs2075601, pulmonary arterial hypertension (PAH), myopathy, and health assessment questionnaire (HAQ) and scleroderma health assessment questionnaire (SHAQ) as important predictors for Gal-3 levels. Conclusion The LGALS3 rs4652 A/C was more frequent in SSc patients and related to lower Gal-3 levels. These findings were corroborated through a GLM to estimate Gal-3 values. Also, by model equations, Gal-3 levels may be predicted by HAQ, SHAQ, PAH, myopathy, and LGALS3 rs4652 and rs2075601 factors. In these ways, we suggest that galectins may be promising biomarkers to identify susceptibility to SSc as well as to identify HAQ, SHAQ, PAH, and myopathy outcomes.

Comprehensive analysis of the major histocompatibility complex in systemic sclerosis identifies differential HLA associations by clinical and serological subtypes

ObjectiveThe greatest genetic effect reported for systemic sclerosis (SSc) lies in the major histocompatibility complex (MHC) locus. Leveraging the largest SSc genome-wide association study, we aimed to fine-map this region...

Natural Killer Cells: Potential Biomarkers and Therapeutic Target in Autoimmune Diseases?

Autoimmune diseases recognize a multifactorial pathogenesis, although the exact mechanism responsible for their onset remains to be fully elucidated. Over the past few years, the role of natural killer (NK) cells in shaping immune responses has been highlighted even though their involvement is profoundly linked to the subpopulation involved and to the site where such interaction takes place. The aberrant number and functionality of NK cells have been reported in several different autoimmune disorders. In the present review, we report the most recent findings regarding the involvement of NK cells in both systemic and organ-specific autoimmune diseases, including type 1 diabetes (T1D), primary biliary cholangitis (PBC), systemic sclerosis, systemic lupus erythematosus (SLE), primary Sjögren syndrome, rheumatoid arthritis, and multiple sclerosis. In T1D, innate inflammation induces NK cell activation, disrupting the Treg function. In addition, certain genetic variants identified as risk factors for T1D influenced the activation of NK cells promoting their cytotoxic activity. The role of NK cells has also been demonstrated in the pathogenesis of PBC mediating direct or indirect biliary epithelial cell destruction. NK cell frequency and number were enhanced in both the peripheral blood and the liver of patients and associated with increased NK cell cytotoxic activity and perforin expression levels. NK cells were also involved in the perpetuation of disease through autoreactive CD4 T cell activation in the presence of antigen-presenting cells. In systemic sclerosis (SSc), in addition to phenotypic abnormalities, patients presented a reduction in CD56hi NK-cells. Moreover, NK cells presented a deficient killing activity. The influence of the activating and inhibitory killer cell immunoglobulin-like receptors (KIRs) has been investigated in SSc and SLE susceptibility. Furthermore, autoantibodies to KIRs have been identified in different systemic autoimmune conditions. Because of its role in modulating the immune-mediated pathology, NK subpopulation could represent a potential marker for disease activity and target for therapeutic intervention.

Genetic Susceptibility to Systemic Sclerosis in the Greek-Cypriot Population: A Pilot Study.

Background: Systemic Sclerosis (SSc), also known as scleroderma, is an autoimmune rheumatic disease, which is clinically subdivided into two major subgroups; limited (lcSSc) and diffuse cutaneous scleroderma (dcSSc). Even though the SSc etiologies remains unclear, some HLA and non-HLA genetic variants have been associated with the disease.Aim: This study was designed to evaluate the associations between several HLA-related genetic variants and SSc in the Greek-Cypriot population.Methods: Forty-one SSc patients and 164 controls were genotyped at 18 selected single nucleotide polymorphisms (SNPs) using restriction fragment length polymorphism analyses, Sanger sequencing, and a multiplex SNaPshot minisequencing assay. Logistic regression analysis under the log-additive model was used to evaluate all possible associations between these SNPs and SSc; nominal statistical significance was assumed at p < 0.05.Results: Associations of SSc with SNPs rs3117230, rs3128930, and rs3128965 within the HLA-DPB1 and HLA-DPB2 regions were observed in the Greek-Cypriot population at the level of p < 0.05. However, none of these associations survived a Bonferroni correction. The direction of the effect is consistent with the direction reported in previous studies. In addition, allele frequencies of the majority of the selected SNPs in the Greek-Cypriot population are similar to those reported in the European population.Conclusion: This study initiates the genetic investigation of SSc in the Greek-Cypriot population, a relatively small newly investigated population. Further investigation with a larger sample size and/or additional SSc susceptibility loci may confirm the association of some of these variants with SSc in the Greek-Cypriot population that could potentially be used for predictive testing.

The contribution of epigenetics to the pathogenesis and gender dimorphism of systemic sclerosis: a comprehensive overview.

Systemic sclerosis (SSc) is a life-threatening connective tissue disorder of unknown etiology characterized by widespread vascular injury and dysfunction, impaired angiogenesis, immune dysregulation and progressive fibrosis of the skin and internal organs. Over the past few years, a new trend of investigations is increasingly reporting aberrant epigenetic modifications in genes related to the pathogenesis of SSc, suggesting that, besides genetics, epigenetics may play a pivotal role in disease development and clinical manifestations. Like many other autoimmune diseases, SSc presents a striking female predominance, and even if the reason for this gender imbalance has yet to be completely understood, it appears that the X chromosome, which contains many gender and immune-related genes, could play a role in such gender-biased prevalence. Besides a short summary of the genetic background of SSc, in this review we provide a comprehensive overview of the most recent insights into the epigenetic modifications which underlie the pathophysiology of SSc. A particular focus is given to genetic variations in genes located on the X chromosome as well as to the main X-linked epigenetic modifications that can influence SSc susceptibility and clinical phenotype. On the basis of the most recent advances, there is realistic hope that integrating epigenetic data with genomic, transcriptomic, proteomic and metabolomic analyses may provide in the future a better picture of their functional implications in SSc, paving the right way for a better understanding of disease pathogenesis and the development of innovative therapeutic approaches.

TNFA -308G>A and -238G>A polymorphisms and risk to systemic sclerosis: impact on TNF-α serum levels, TNFA mRNA expression, and autoantibodies.

Systemic sclerosis (SSc) is a rare autoimmune disease with high mortality, characterized by chronic inflammation and fibrosis, which are processes associated with higher serum tumor necrosis factor-α (sTNF-α) levels. TNFA -308G>A and -238G>A polymorphisms have been associated with higher sTNF-α levels. In this study, we genotyped the TNFA -308G>A and -238G>A polymorphisms in 53 SSc patients and 115 unrelated control subjects (CS) from southern Mexico. The TNFA mRNA expression and sTNF-α levels were also quantified by qPCR and enzyme-linked immunosorbent assays, respectively. TNFA -308GA genotype was associated with disease susceptibility according to a codominant genetic model (OR = 3.2, 95% CI 1.05-9.75, p = 0.03), and with higher anti-fibrillarin antibodies (p = 0.01), and higher skin thickening (p = 0.006). TNFA -238GA was not associated with SSc risk. TNFA mRNA expression and sTNF-α levels were similar between SSc patients and CS and were not statistically associated with the TNFA polymorphisms; however, a correlation (rho = 0.362, p = 0.009) between sTNF-α levels with anti-RNA polymerase III antibodies was observed in the SSc patients. In conclusion, the -308G>A polymorphism is a genetic marker of SSc susceptibility in population from southern Mexico, and it is associated with skin thickening and anti-fibrillarin antibodies. In addition, sTNF-α levels correlate positively with the anti-RNA pol III antibodies levels.

Macrophage migration inhibitory factor polymorphisms are a potential susceptibility marker in systemic sclerosis from southern Mexican population: association with MIF mRNA expression and cytokine profile.

Systemic sclerosis (SSc) is a complex autoimmune disease, characterized by microvascular lesions, autoimmunity, and fibrosis. It is suggested that MIF participates in the amplification of the proinflammatory process in SSc; moreover, the promoter polymorphisms - 794 CATT5-8 (rs5844572) and - 173G>C (rs755622) in the MIF gene have been associated with an increase in MIF serum levels in several autoimmune diseases. The aim of this study was to analyze the relationship of the - 794 CATT5-8 and - 173G>C MIF polymorphisms with mRNA expression, MIF serum levels, and the Th1/Th2/Th17 cytokine profile in SSc. A case-control study was carried out that included 50 patients with SSc and 100 control subjects (CS). Both polymorphisms were genotyped by PCR and PCR-RFLP. MIF levels were measured by ELISA kit. The cytokine profile and the MIF mRNA expression were quantified by BioPlex MagPix system and real-time PCR, respectively. An association between the - 794 CATT7 and - 173*C MIF alleles and the 7C haplotype with SSc susceptibility was found (p < 0.05). Also, the 7C haplotype was associated with increased MIF mRNA expression (p =0.03) in SSc. In addition, an increase of IL-1β and IL-6 serum levels in SSc patients was found as well as a positive correlation between MIF serum levels and Th1 and Th17 cytokine profiles. The MIF 7C haplotype is a susceptibility marker for SSc in the southern Mexican population and is associated with MIF mRNA expression. Moreover, there is a positive correlation between MIF serum levels and Th1 and Th17 inflammatory response in SSc.

Brief Report: Whole-Exome Sequencing to Identify Rare Variants and Gene Networks That Increase Susceptibility to Scleroderma in African Americans.

Whole-exome sequencing (WES) studies in systemic sclerosis (SSc) patients of European American (EA) ancestry have identified variants in the ATP8B4 gene and enrichment of variants in genes in the extracellular matrix (ECM)-related pathway that increase SSc susceptibility. This study was undertaken to evaluate the association of the ATP8B4 gene and the ECM-related pathway with SSc in a cohort of African American (AA) patients. SSc patients of AA ancestry were enrolled from 23 academic centers across the US under the Genome Research in African American Scleroderma Patients consortium. Unrelated AA individuals without serologic evidence of autoimmunity who were enrolled in the Howard University Family Study were used as unaffected controls. Functional variants in genes reported in the 2 WES studies in EA patients with SSc were selected for gene association testing using the optimized sequence kernel association test (SKAT-O) and pathway analysis by Ingenuity Pathway Analysis in 379 patients and 411 controls. Principal components analysis demonstrated that the patients and controls had similar ancestral backgrounds, with roughly equal proportions of mean European admixture. Using SKAT-O, we examined the association of individual genes that were previously reported in EA patients and none remained significant, including ATP8B4 (P = 0.98). However, we confirmed the previously reported association of the ECM-related pathway with enrichment of variants within the COL13A1, COL18A1, COL22A1, COL4A3, COL4A4, COL5A2, PROK1, and SERPINE1 genes (corrected P = 1.95 × 10-4 ). In the largest genetic study in AA patients with SSc to date, our findings corroborate the role of functional variants that aggregate in a fibrotic pathway and increase SSc susceptibility.

Changes in macrophage transcriptome associate with systemic sclerosis and mediate GSDMA contribution to disease risk.

ObjectivesSeveral common and rare risk variants have been reported for systemic sclerosis (SSc), but the effector cell(s) mediating the function of these genetic variants remains to be elucidated. While innate immune cells have been proposed as the critical targets to interfere with the disease process underlying SSc, no studies have comprehensively established their effector role. Here we investigated the contribution of monocyte-derived macrophages (MDMs) in mediating genetic susceptibility to SSc.MethodsWe carried out RNA sequencing and genome-wide genotyping in MDMs from 57 patients with SSc and 15 controls. Our differential expression and expression quantitative trait locus (eQTL) analysis in SSc was further integrated with epigenetic, expression and eQTL data from skin, monocytes, neutrophils and lymphocytes.ResultsWe identified 602 genes upregulated and downregulated in SSc macrophages that were significantly enriched for genes previously implicated in SSc susceptibility (P=5×10−4), and 270 cis-regulated genes in MDMs. Among these, GSDMA was reported to carry an SSc risk variant (rs3894194) regulating expression of neighbouring genes in blood. We show that GSDMA is upregulated in SSc MDMs (P=8.4×10−4) but not in the skin, and is a significant eQTL in SSc macrophages and lipopolysaccharide/interferon gamma (IFNγ)-stimulated monocytes. Furthermore, we identify an SSc macrophage transcriptome signature characterised by upregulation of glycolysis, hypoxia and mTOR signalling and a downregulation of IFNγ response pathways.ConclusionsOur data further establish the link between macrophages and SSc, and suggest that the contribution of the rs3894194 risk variant to SSc susceptibility can be mediated by GSDMA expression in macrophages.

FOXP3, ICOS and ICOSL gene polymorphisms in systemic sclerosis: FOXP3 rs2294020 is associated with disease progression in a female Italian population

Systemic sclerosis (SSc), an autoimmune disorder, is characterized by vasculopathy, inflammation, progressive perivascular and interstitial fibrosis. Its pathogenesis is largely unknown, however strong evidences suggest that genetic predisposition may contribute to SSc development.Several gene polymorphisms involved in regulatory T cell function have been identified in many autoimmune diseases, including SSc. Moreover, dysregulation of co-stimulatory and/or co-inhibitory signals, including ICOS signalling, can lead to autoimmunity. The aim of the present study was to investigate the association of the FOXP3 rs2294020, ICOS rs6726035 and ICOSL rs378299 SNPs with both the susceptibility and the progression to SSc in an Italian case-series of patients.SNP genotyping results were successfully obtained from a total of 350 subjects including 166 individuals with SSc and 184 healthy controls. Although analysis tests did not show any significant associations between the SNPs under study and susceptibility to SSc, the occurrence of FOXP3 rs2294020 in female patients was associated with decreased time to progression from early to definite SSc (allelic model: HR=1.43; CI=1.03-1.99; p=0.03; dominant model: HR=1.54; CI=1.04-2.28; p=0.03). The inclusion of presence of ACA autoantibodies in the model did not significantly change the estimates. No conclusions can be drawn for the susceptibility to the disease or the time to progression in men due to the low statistical power. This study provides evidence of the association of rs2294020 with SSc evolution in female patients, modulating the time of progression from the diagnosis of early SSc to the diagnosis of definite SSc, while no effect on SSc susceptibility per se was found. rs2294020 may be considered a disease-modifying gene-variant rather than a disease-susceptibility SNP in SSc.

Epigenetics: The Future Direction in Systemic Sclerosis.

Systemic sclerosis (SSc) is an immune-mediated connective tissue disease of which the aetiology is still unclear. Previous genetic studies including candidate-gene studies and genomewide association studies have identified a number of genetic variations that confer risk to SSc. However, these variants, such as single nucleotide polymorphisms, cannot completely explain the SSc susceptibility and the diversity in the clinical symptoms of SSc patients. The contribution of epigenetic mechanisms as a link between genetics and environmental triggers represents promising field in understanding the pathogenesis of SSc. The aim of this review was to present the current knowledge on epigenetic mechanisms and highlight novel directions in diagnostic and therapeutical approaches.

Neuer Genlocus beeinflusst Anfälligkeit für systemische Sklerose

Lopez-Isac E et al. Influence of TYK2 in systemic sclerosis susceptibility: A new locus in the IL-12 pathway.

Human Leukocyte Antigen and Systemic Sclerosis in Japanese: The Sign of the Four Independent Protective Alleles, DRB1*13:02, DRB1*14:06, DQB1*03:01, and DPB1*02:01.

ObjectiveSeveral studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. Anti-centromere antibodies (ACA) and anti-topoisomerase I antibodies (ATA) are found in SSc patients. Here, we sought to identify HLA alleles associated with SSc in Japanese, and explored their associations with SSc phenotypes including the presence of autoantibodies.MethodsAssociations of HLA-DRB1, DQB1, and DPB1 were analyzed in 463 Japanese SSc patients and 413 controls.ResultsWe found that DRB1*13:02 (P = 0.0011, Pc = 0.0319, odds ratio [OR] 0.46, 95% confidence interval [CI] 0.29–0.73), DRB1*14:06 (P = 6.60X10-5, Pc = 0.0020, OR 0.05, 95%CI 0.01–0.41), DQB1*03:01 (P = 0.0009, Pc = 0.0150, OR 0.56, 95%CI 0.40–0.79), and DPB1*02:01 (P = 5.16X10-6, Pc = 8.77X10-5, OR 0.52, 95%CI 0.39–0.69) were protectively associated with SSc. In addition, these four alleles seemed to be independently associated with the protection against the susceptibility of SSc. On the other hand, we could not find predisposing alleles for overall SSc. With respect to SSc subsets, a tendency for these four alleles to be protectively associated was observed. However, there was a significant association between DRB1*01:01, DRB1*10:01, DQB1*05:01, and DPB1*04:02 and the susceptibility to SSc with ACA. On the other hand, the presence of DRB1*15:02, DQB1*06:01, DPB1*03:01, and DPB1*09:01 was associated with SSc with ATA.ConclusionThus, the present study has identified protective associations of the four HLA class II alleles with overall Japanese SSc and predisposing associations of HLA class II alleles with Japanese SSc subsets.

Functional variants of Fc gamma receptor (FCGR2A) and FCGR3A are not associated with susceptibility to systemic sclerosis in a large European study (EUSTAR) (vol 37, pg 1673, 2010)

Functional variants of Fc gamma receptor (FCGR2A) and FCGR3A are not associated with susceptibility to systemic sclerosis in a large European study (EUSTAR) (vol 37, pg 1673, 2010)

Association of interleukin-1 family cytokines single nucleotide polymorphisms with susceptibility to systemic sclerosis: an independent case-control study and a meta-analysis.

The aim of our study was to investigate the association of five single nucleotide polymorphisms in interleukin-1 (IL-1) gene with susceptibility to systemic sclerosis (SSc) in a Chinese population. A total of 58 SSc patients and 113 healthy controls were enrolled. TaqMan allele discrimination assay was performed to detect the genotyping of IL-1A -889C/T (rs1800587), IL-1B -511C/T (rs16944), IL-18 -607C/A (rs1946518), IL-18 -137G/C (rs187238) and IL-33 rs7044343. The association between these SNPs and SSc risk was analyzed. Furthermore, a meta-analysis of relevant studies on the association of IL-1A -889C/T (rs1800587) and IL-1B -511C/T (rs16944) with the susceptibility to SSc was performed. Through the genotyping, significant associations for SSc were found for: IL-1A -889C/T genotype frequencies (P=0.000), dominant model (P=0.000), recessive model (P=0.001) and allele T frequency (P=0.000). Among SSc patients, dyspnea was significantly associated with IL-18 -607C/A genotype frequency and IL-33 rs7044343 allele frequency (P=0.037, P=0.042, respectively). In addition, elevated erythrocyte sedimentation rate was significantly associated with IL-18 -137G/C (rs187238) genotype and allele frequency (P=0.019, P=0.006, respectively). While meta-analysis showed there was no significant association between IL-1A -889C/T polymorphism and SSc, for IL-1B -511C/T (rs16944), significant associations were found in the comparison of allele C versus T (OR 1.267, 95% CI 1.016-1.580) by combined different outcomes. Results showed that IL-1A -889C/T (rs1800587) was associated with SSc susceptibility in the Chinese population. However, this association was not supported by a meta-analysis of all relevant studies. Further investigations are required to verify our findings.

The IL-33 gene is related to increased susceptibility to systemic sclerosis.

Systemic sclerosis (SSc) is a chronic inflammatory disease characterized by widespread fibrosis of the skin and several visceral organs. The pro-fibrotic potential of interleukin (IL)-33 has been demonstrated by in both in vitro and in vivo settings; moreover, increased level of IL-33 has also been reported in patients with SSc. Therefore, the aim of the present study was to detect the potential association of IL-33 gene polymorphisms on the susceptibility of SSc. A total of 300 SSc patients and 280 healthy controls (HC) were enrolled in this multicentric preliminary candidate gene study. DNA samples were harvested using an appropriate commercial DNA isolation kit. Four single nucleotide polymorphisms (SNPs) of IL-33 gene (rs7044343, rs1157505, rs11792633 and rs1929992) were genotyped using the appropriate commercial primer/probe sets on real-time PCR. There was no significant difference in terms of the allelic distributions and minor allele frequencies of evaluated four IL-33 polymorphisms between the SSc and HC groups (P>0.05 for all). Moreover, the genotypic distributions of rs1157505, rs11792633 and rs1929992 polymorphisms were not significantly different (P>0.05 for all). However, CC genotype of rs7044343 SNP was significantly higher in the SSc group compared to the HC group (P=0.013, OR 1.75, 95% CI 1.12-2.72). This preliminary candidate gene study demonstrates that rs7044343 polymorphism of IL-33 gene is associated with the susceptibility to the SSc in Turkish population. It may be suggested that IL-33 gene may be a candidate gene to research in SSc.