Objective: T-box expressed in T cells (T-bet) and GATA-binding protein 3 (GATA-3) are transcriptional factors that play a crucial role in Th1 and Th2 development. We investigated the immunomodulatory roles of T-bet and GATA-3 and Th1/Th2 related cytokines in the pathogenesis of systemic lupus erythematosus (SLE) and their association with disease activity.
Methods: Gene expressions of T-bet, GATA-3, interferon-gamma (IFN-gamma), and interleukin 4 (IL-4) in peripheral blood mononuclear cells, and plasma concentrations of the Th1/Th2 cytokines IFN-gamma, IL-18, and IL-4, were assayed in 80 patients with SLE and 40 sex and age matched healthy subjects by real-time quantitative polymerase chain reaction and ELISA.
Results: The mRNA levels of T-bet and IFN-gamma and the relative expression levels of T-bet/GATA-3 and IFN-gamma/IL-4 were significantly higher, in contrast to the lower expressions of GATA-3 and IL-4, in SLE patients than controls (all p < 0.05). In all SLE patients, there were significant correlations in mRNA expression of T-bet with IFN-gamma (r = 0.590, p < 0.0001), and of GATA-3 with IL-4 (r = 0.245, p = 0.029). The relative expressions of T-bet/GATA-3 and IFN-gamma/IL-4 correlated with lupus disease activity (r = 0.229, p = 0.042; r = 0.231, p = 0.040, respectively). Plasma IL-18 concentration was increased significantly in all SLE patients (p < 0.05). The elevated plasma Th1/Th2 cytokine ratio IL-18/IL-4 correlated positively with disease activity in all SLE patients (r = 0.250, p = 0.025).
Conclusion: There is an association between expression of Th1/Th2 transcription factors and cytokines in SLE. The elevated gene expressions of Th1/Th2 transcription factors and cytokines should provide a useful tool for assessing the functional status of T-helper lymphocytes in SLE disease development.