Th17 pathway genes polymorphisms in Algerian patients with systemic sclerosis

ARTIGO ORIGINAL Th17 pathway genes polymorphisms in Algerian patients with systemic sclerosis Mellal Y1, Allam I1, Tahiat A1, Abessemed A2, Nebbab R3, Ladjouze A2, Djidjik R1 ACTA REUMATOL PORT. 2018;43:269-278 AbstrAct for the A allele), and with interstitial lung disease (p = 0.025 for the AG genotype) have also been found. Conclusion: The study revealed that IL-17F and IL-21 genes were associated with systemic sclerosis (SSc) susceptibility and that IL-17A, IL-17F, IL-21 and IL-23R genes influence the clinical and immunological features, which suggest the implication of Th17 cells in SSc pathogenesis. Objective: Th17 cells have involved in the pathogenesis of several autoimmune diseases including systemic sclerosis (SSc). The aim of our study was to investigate an association of IL-17A, IL-17F, IL-21, IL-23R and STAT3 genes with SSc susceptibility, and clinical and immunological phenotypes. Patients and methods: The case-control study included 136 patients suffering from SSc and 317 healthy controls of the Algerian population. Eight single nucleotide polymorphisms (SNP) of genes encoding Th17 pathway were genotyped using TaqMan allelic discrimination assays. These SNPs are: IL-17A (rs2275913), IL17F (rs2397084 and rs763780), IL-21 (rs6822844), IL-23R (rs10489629, rs11209026 and rs1343151) and STAT3 (rs2293152). Results: The current study showed a significant association of rs2397084 SNP (p = 0.049 and p = 0.036 for the TT genotype and the T allele, respectively) and rs6822844 SNP (p = 6.6 10-4 for the G allele) with systemic sclerosis (SSc) susceptibility. Also, we found an association of rs2275913 SNP (pc = 0.015 and p = 0.005 for the GG genotype and the G allele, respectively) and rs6822844 SNP (pc = 0.024 for the TT genotype) with digestive involvement. Also an association with anti-RNAPIII antibodies production have been found with rs6822844 SNP (pc = 0.012 and pc = 0.029 for the GT genotype and the T allele, respectively). Association of rs10489629 SNP with digital infarcts (p = 0.043 for the C allele), interstitial lung disease (p = 0.045 for the CT genotype) and anti-SSA antibodies production (p = 0.001 and p = 0.008 for the CT genotype and the T allele, respectively) have been showed. Finally, an association of rs1343151 SNP with digital infarcts (p = 0.028 Keywords: Systemic sclerosis; Th17 cell; Polymorphism. IntroductIon Systemic sclerosis (SSc) is an autoimmune connective tissue disease characterized by excessive collagen deposition in the skin and internal organs with associated vasculopathy and autoantibody production1. SSc is a multifactorial disease in which genetic factors play a crucial role, in fact the genome-wide and the candidate gene studies allowed to associate HLA (human leukocyte antigen) and non HLA genes to the onset of the SSc, to subsets of the disease, or to autoantibodies production2–7. Among the susceptibility genes to SSc, many encode proteins of immune response, moreover several studies showed the presence of immune cells in inflammatory skin infiltrate of sclerodermic patients (monocytes/macrophages, mast cells and T cells), generally in perivascular localization8–10, the majority of T cells infiltrating the lesions express activation markers and has a limited T cell receptor (TCR) repertoire thus indicating their antigen induced expansion8,10–12. The T cells can cause the activation of fibroblasts either by direct contact or by the action of secreted cytokines and chemokines13. In addition, autoreactive T cells can interact with B cells and lead to the autoantibodies production13,14. Several studies showed that the predominate cells in the lesions and the blood of scleroderma patients was the T Helper (Th)2 cells15–17, these cells are largely incriminated in the SSc pathogenesis because of the potent 1. Beni Messous University Hospital, Department of Immunology and Algiers Faculty of Medicine, University of Algiers 1, Algiers, Algeria 2. Specialized Medical Center of Ben Aknoun, Department of Rheumatology, Algiers, Algeria 3 Beni Messous University Hospital, Department of Epidemiology and Preventive Medicine, Algiers, Algeria ÓRGÃO OFICIAL DA SOCIEDADE PORTUGUESA DE REUMATOLOGIA 269 Th17 paThway genes polymorphisms in algerian paTienTs wiTh sysTemic sclerosis profibrotic action of their secreted cytokine interleukin (IL)-4 which induces the fibroblasts proliferation, and increases the production of collagen and tumor growth factor (TGF)-b, furthermore, IL-4 contributes to mononuclear cells infiltration18–20. As to Th1 cells, minority during the SSc, they have an anti- fibrotic effect exerted essentially via IFN-g which has antagonist effects to those of IL-4. However, these cells may be involved in the inflammatory process that occurs early in the course of the disease13. Constituting the third population of T helper after Th1 and Th2 populations, the Th17 cells have been assigned a pivotal role in the pathophysiology of various autoimmune diseases such as the Crohn's disease, the rheumatoid arthritis and the multiple sclerosis21,22. Even if their role in SSc has not been established several studies have found that Th17 cells at higher frequency in the peripheral blood and in the bronchoalveolar lavage (BAL) fluid of patients with scleroderma compared to healthy subjects 13,23–30. It was also found elevated levels of IL-17 in serum 29,31 and IL-17A mRNA29,32, with an increase of IL-17A positivity in skin biopsies of patients with SSc28,33. IL-23, crucial cytokine in Th17 differentiation, was also found at high levels in SSc34. Furthermore, IL-1b, IL-6 and TGF-b, necessary cytokines for the differentiation of Th17 and for pro-fibrotic processes promotion are found at higher levels in the serum and tissues of patients with SSc24,35–37. All evidences are in favor of Th17 cells involvement in the pathogenesis of SSc. This is why our research work focused on studying polymorphisms affecting the genes encoding key cytokines, their receptor and transcription factor involved in Th17 pathway: IL-17A (rs2275913), IL-17F (rs2397084 and rs763780), IL-21(rs6822844), IL-23R (rs10489629, rs11209026 and rs1343151) and STAT3 (rs2293152). Our aim was to highlight potential associations of single nucleotide polymorphisms (SNPs) with the occurrence of SSc, disease subsets, clinical features, and produced autoantibodies. the Rheumatology department of the specialized center of Ben Aknoun and Beni Messous university hospital in Algiers, Algeria8. Table I records their demographic and clinical features. 317 healthy controls divided in 35 men and 282 women (sex ratio W/M: 8.06; mean age: 36.65 ± 12.07) and without any familial history of autoimmune diseases were also included in the study. AutoAntIbody AnAlysIs All patients were tested for antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) test using HEp-2 substrate. They were also tested for antitopoisomerase antibodies (ATA), anti-centromere antibodies (ACA), anti-RNA poly (...truncated)