Transforming growth factor-β increases interleukin-13 synthesis via GATA-3 transcription factor in T-lymphocytes from patients with systemic sclerosis

Introduction: Transforming growth factor (TGF)-beta and interleukin (IL)-13 play a crucial role in the pathogenesis of systemic sclerosis (SSc), partly through activation of collagen production that leads to fibrosis. The aim of the present study was to determine whether TFG-beta alters IL-13 production in T lymphocytes from patients with SSc from that seen in those of healthy donors. Methods: IL-13 mRNA and protein synthesis under TFG-beta exposure was measured in circulating T lymphocytes from healthy donors and patients with SSc and also in the Jurkat Th2 T-cell line, using quantitative real-time PCR and fluorescence-activated cell sorting analysis, respectively. The involvement of Smad and GATA-3 transcription factors was assessed by using specific inhibitors and small interfering RNA, and the binding capacity of GATA-3 to the IL-13 gene promoter was evaluated by chromatin immunoprecipitation assay. Results: TGF-beta induced a significant decrease in IL-13 mRNA and protein levels in lymphocytes from healthy donors (mean [+/- SD] inhibition of 30 % +/- 10 % and 20 % +/- 7 %, respectively; p < 0.05). In contrast, TGF-beta promoted a significant increase in IL-13 mRNA levels and IL-13 synthesis by CD4(+) and CD8(+) T-cell subtypes from patients with SSc, with respective increases of 2.4 +/- 0.3-fold, 1.6 +/- 0.05-fold and 2.7 +/- 0.02-fold. The involvement of the Smad signaling pathway and upregulation of GATA-3 binding capacity on the IL-13 promoter in lymphocytes from patients with SSc contributed to the effect of TGF-beta on IL-13 production. Conclusions: These results demonstrate that TGF-beta upregulates IL-13 synthesis through GATA-3 expression in the T lymphocytes of patients with SSc, confirming that the GATA-3 transcription factor can be regarded as a novel therapeutic target in patients with SSc.