Interleukin-2-inducible T-cell kinase expression and relation to disease severity in systemic lupus erythematosus

Background: Interleukin-2 inducible T-cell kinase (ITK) is expressed in T cells, and plays an important role in autoimmune inflammatory diseases through regulating the balance of Th17/Treg. However, its role in human systemic lupus erythematosus (SLE) remains unclear. The present study aims to measure the activation status of ITK in T cells from SLE patients and healthy controls, and identify its possible correlation to disease severity. We also discuss the serum levels of Th17, Treg related cytokines including IL-17, IL-21, IL-22, IL-10, analyzing correlation between ITK and Th17/Freg related cytokines. Methods: Peripheral blood samples were drawn from 42 patients with SLE and 43 healthy blood donors, and the phosphorylation of ITK protein was studied in T cells using flow cytometry. In addition, serum levels of Th17/Freg related cytokines were studied with enzyme-linked immunosorbent assay (ELISA). Results: Percentages of CD4(+) pITK(+) T cells, CD8(+) pITK(+) T cells were higher in SLE patients compared with controls, and were positively related to disease activity, some clinical and laboratory parameters. Percentages of CD4(+) pITK(+) T cells, CD8(+)pITK(+) T cells were more prominent in active SLE patients compared with less active patients. Serum levels of Th17 and Treg related cytokines were higher in patients compared with controls. CD4(+)pITK(+) T cells were related to levels of IL-17, IL-21. Conclusion: These data indicate that increased ITK expression could act as a disease activity marker and as a risk factor for involvement in SLE, but it still needs further study to confirm. (C) 2016 Elsevier B.V. All rights reserved.