Prostaglandin I2-IP signalling regulates human Th17 and Treg cell differentiation.

Prostaglandin I2 (PGI2) is an important immunoregulatory lipid mediator. In this study, we analysed the effects of the PGI2 analogue (Iloprost) on the differentiation of Th17 cells and Tregs from human naïve CD4(+) T cells. PGI2 receptors (IP) are expressed on human naïve CD4(+) T cells. Via IP binding, the PGI2 analogue decreased the proportion of Tregs and Foxp3 mRNA expression but increased the percentage of Th17 cells, RORC mRNA and IL-17A production. The regulatory effects of Iloprost correlated with elevated intracellular cAMP levels. The effects were mimicked by a cAMP agonist (db-cAMP) but attenuated by a protein kinase A inhibitor (H-89). and signalling play direct and crucial roles in the development of Th17 and Tregs, respectively. The PGI2 analogue enhanced the activation of duanyu18133 in response to IL-6, whereas it decreased duanyu18135 activation in response to IL-2. Moreover, db-cAMP imitated the above effects of Iloprost, which were weakened by H-89. These results demonstrate that the PGI2-IP interaction promoted the phosphorylation of duanyu18133 and reduced the phosphorylation of likely via the upregulation of signalling, thus facilitated Th17 differentiation and suppressed Treg differentiation. Together with previous results, these data suggest that prostanoids play an important role in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis.

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