Determination of FOXP3 TSDR methylation and cytokine levels in the blood of patients with psoriasis

Psoriasis is a common, immune-mediated inflammatory disease which is characterized by red colored plaques with well-defined borders and silvery-white dry scales on the skin. Due to psoriasis being a life-long disease and the lack of definitive treatment of the disease, patients are affected by the poor life quality. Regulator T (Treg) cells, which are responsible for suppressing the activity of effector T cells, are characterized by high levels of FOXP3 expression. The stability of FOXP3 expression is associated with the methylation of TSDR, a CpG-rich and conserved intronic region. Methylation level of Treg cells is thought to have an impact on the pathogenesis of autoimmune diseases and psoriasis. Although proinflammatory cytokines (IL-17 and IL-36) and antiinflammatory cytokines (IL-10 and IL-35) are thought to be related to the pathogenesis of psoriasis, no definite result has been obtained. In this study, it was aimed to determine the levels of FOXP3 TSDR methylation, FOXP3 mRNA expression and selected cytokines in the peripheral blood samples of patients with psoriasis and to investigate their relationship with disease severity and treatment status. To perform this task, blood samples taken from patients with psoriasis (n=38) and healthy control group (n=20). To determine FOXP3 TSDR methylation status, FOXP3 mRNA expression and interleukin levels; HRM-PCR, real-time PCR and ELISA methods were performed respectively. In the patient and control groups, FOXP3 TSDR was methylated. There was no significant difference between the melting temperature values and FOXP3 mRNA levels of two groups. Among the cytokine results, only IL-10 was found to be significantly lower in patients. There was positive correlation between IL-35 levels and psoriasis area and severity index (PASI) scores in the patient group; IL-17A levels and PASI scores in patients with mild psoriasis; IL-17A and FOXP3 expression levels, IL-36G levels and PASI scores in patients with moderate-to-severe psoriasis. There was negative correlation between IL-35 and FOXP3 expression levels in patients with mild psoriasis. In conclusion, it is suggested to analyse the FOXP3 TSDR methylation level of patients with psoriasis using more precise methods. The investigated cytokines may be important indicators of disease severity. Therefore, it would be better to use more detailed grouping and larger sample sizes in further studies.