Analysis of key markers: IL-10/sHLA-G in psoriasis patients and the identification of 14-bp INDEL in the HLA-G gene.

Abstract

BACKGROUND Psoriasis is a chronic inflammation resulting from interactions between immunological and genetic factors. An important tolerogenic role in this autoimmunological disease is played by HLA-G, which is modulated by IL-10. Therefore, this study (N=80) aimed to evaluate changes in the serum sHLA-G and IL-10 levels in active psoriasis vulgaris and in the early stages of treatment with Methotrexate (MTX) compared to healthy controls. The 14-bp INDEL of the HLA-G gene was evaluated to find possible associations with clinical and laboratory variables. METHODS The level of sHLA-G and IL-10 in serum was evaluated (ELISA tests) in patients before the first dose of MTX and at week 12 of treatment, compared to healthy control donors. The 14-bp INDEL in 3'UTR of the HLA-G gene was identified using gDNA templates isolated from full blood. HLA-G amplicons were obtained by PCR, separated by electrophoresis and sequenced. RESULTS The mean serum IL-10 level was 4.653 ±3.33 pg/mL in psoriatic patients, 13.3 ± 9.64 pg/mL after short MTX treatment, compared to 6.23 pg/mL in healthy controls. In addition, the serum level of sHLA-G was 0.275± 0.03 ng/mL and 0.332 ± 0.06 ng/mL in patients before and after MTX treatment, respectively, and 0.302±0.08 ng/mL in the control group. A correlation was found (r= -0.43; p<0.005) between the IL-10 and BSA serum levels in psoriasis patients after MTX treatment, indicating health improvement. The three genotypes identified in the 3'UTR of the HLA-G revealed no association with sHLA-G level in serum. CONCLUSIONS The mean levels of sHLA-G and the key anti-inflammatory cytokine IL-10 in the blood of pre-treatment psoriasis patients are low and indicate that the immunotolerance mechanisms have failed. Treatment of psoriasis patients with low systemic levels of sHLA-G and IL-10 brings them to the same or higher protein levels, respectively, as in healthy donors. Higher sHLA-G levels in healthy donors and after MTX treatment, compared to the sHLA-G levels in the acute phase of psoriasis, indicates its immune system surveillance function.