Expression of il-17 and il-23r in t lymphocytes from Thai SLE patients

Abstract

Systemic Lupus Erythematosus (SLE) is an autoimmune disorder which affects various systems. The exact etiology of SLE is not known but the defects in cytokine network and the functions of T lymphocytes (T cells) may play a vital role. It was reported that SLE patients showed elevated level of various cytokine such as IL-1β, IL-6 and IL-23 and recent reports indicated that CD4+ T cells mainly producing IL-17 called Th17 play a vital role in various autoimmune disorders. Th17 differentiation is under the influence IL-1β/IL-6 and IL-23. Moreover, IL-23 is also vital in maintaining the Th17 phenotype. In addition to Th17 cells, IL-17 is also produced by various cell types. The aim of this study was to investigate the level of cytokine IL-17 in 29 SLE patients that were divided based on the severity of disease by SLEDAI score. Sixteen active, 13 inactive SLE patients and 10 normal subjects were recruited in this study. The frequency of CD4+IL-23R+ and CD8+IL-23R+ T cells in PBMC, as analyzed by flow cytometry, from patients were significantly higher than those of controls (p<0.05), in both freshly isolated PBMC (day 0) and PBMC stimulated by anti-CD3 and CD-28 antibodies (day 3). When IL-17 expression was measured, higher frequency of CD4+IL-17+ and significantly higher frequency of CD8+IL-17+ T cells in PBMC on day 3 from patients were observed. The level of IL-17 in serum and plasma were measured by ELISA, but only two SLE were found to show detectable IL-17 at 5.12, 6.78 and 5.75, 8.50 pg/ml, respectively. When IL-23 level measured by ELISA, all samples showed negative results. The expression of IL-17A mRNA was analyzed by quantitative realtime RT-PCR, higher but not statistically significant level was observed in PBMC from patients. Taken together, these results suggest that T lymphocytes in SLE patients increase IL-23R and IL-17 expression, which may play an important role in pathology of SLE.