Tumor necrosis factor alpha and interleukin?2 gene polymorphisms in patients with psoriasis and psoriatic arthritis

Psoriasis is a chronic inflammatory disorder of the skin that is mediated by T cells, dendritic cells and inflammatory cytokines. Although the primary defect has not been fully explained, it is currently considered as multifactorial and multigenetic. In this study our aim is to investigate association between TNF-? (-238, -308 and -857), IL-2 (-330) and IL-2RB gene polymorphisms and susceptibility for psoriasis and psoriatic arthritis.Seventy four patients with psoriasis and 74 healthy volunteers with no personal and family history of psoriasis were enrolled in the study. In all study subjects, TNF-? (-238, -308 and -857), IL-2 (-330) and IL-2RB gene polymorphisms determined by PCR-RFLP (Polymerase chain reaction-restriction fragment length polymorphism) method. Then data compared between the study groups.There were no significant differences in the polymorphisms of TNF-? (-857) and IL2RB genes, between psoriasis patients and healthy controls. AA genotype in TNF? (-308) (p=0.013), AA genotype in TNF-? (-238) (p=0.028) and GG, TT genotypes in IL-2 (-330) (p=0.037, p=0.009) are significantly increased in patients with psoriasis in comparison with control group. However GG genotype in TNF-? (-238) (p=0.016) and GT genotype in IL-2 (-330) (p=0.001) are significantly decreased in patients with psoriasis in comparison with control group. Also gene polymorphisms were analyzed according to the clinical characteristics of the psoriasis patients. IL-2 (-330) GG genotype frequency (p=0.021) was significantly decreased and the frequency of IL-2(-330) TT genotype (p=0.014) was significantly increased among patients with psoriatic arthritis in comparison with psoriasis patients. The frequency of IL-2 (-330) TT genotype (p=0.043) was significantly increased in mild psoriasis pattient according to moderate-severe psoriasis patients. Also IL-2RB CC genotype (p=0.009) was significantly increased, among patients with late-onset psoriasis in comparison with early onset psoriasis group. IL-2RB TC genotype frequency (p=0.017) was significantly decreased and TT genotype frequency (p=0.014) was significantly increased in patients with positive family history of psoriasis according to negative family history patients.In conclusion, polymorphisms of TNF-? (-238 and 308) and IL-2 (-330) genes may contribute to susceptibility to psoriasis. Also the IL-2 (-330) TT genotype may be a risk factor for the development of psoriatic arhritis, whereas the GG genotype may be a protective factor against psoriatic arthritis.