The regulatory effects of a epoprostenol analog on the differentiation of CD4+ T cells to Treg cells and the possible mechanism

Abstract

Objective To investigate the roles of a epoprostenol(PGI2) analog (Iloprost) in regulating the differentiation of CD4+ T cells to Treg cells and the possible mechanism. Methods Naive CD4+ T cells were isolated from human peripheral blood samples by using the magnetic-activated cell sorting (MACS) and then cultured under Treg-polarizing condition. The percentages of Treg cells and the expression of Foxp3 at mRNA level were respectively measured by using flow cytometry and RT-PCR for evaluation the effects of Iloprost on the differentiation of CD4+ T cells to Treg cells. The cAMP accumulation assay was used to detect the level of intracellular cAMP. Flow cytometry analysis was performed to detect the phosphorylation of signal transducer and activator of transcription 5 (STAT5). Results Iloprost decreased the percentage of Treg cells and inhibited the expression of Foxp3 at mRNA level in a dose dependent manner (P 0.05). H-89, a protein kinase A inhibitor, inhibited the Iloprost-induced expression of cAMP in Treg cells. Moreover, Iloprost inhibited the IL-2 mediated phosphorylation of STAT5 (P 0.05). The Iloprost-mediated down-regulation of pSTAT5 was blocked by using H-89. Conclusion PGI2 could activate the cAMP-PKA signaling pathway by binding to the IP receptor, resulting in inhibited phosphorylation of STAT5 and suppressed differentiation of naive CD4+ T cells to Treg cells. Key words: PGI2 analog; Regulatory T cell; Differentiation; Signal pathway