Roles and Mechanisms of TGR5 in the Modulation of CD4+ T Cell Functions in Myocardial Infarction.

Bile acid receptor TGR5 has been proved to play protective roles in the process of myocardial infarction (MI). Recently, we found spleen weight of Tgr5+/+ mice was increased at 7-day post-MI but not in Tgr5-/- mice. Since the spleen is one of the main resources of immune and inflammatory cells post-MI, we conducted flow cytometry analysis of multiple immune cells in the heart post-MI. It showed the recruitment of CD4+ T cells and CD8+ T cells was continuously more in the heart of Tgr5-/- mice post-MI until 7 days after MI. Furthermore, CD4-specific TGR5 depletion mice exhibited aggravated ischemic injury. The mRNA expressions of the markers of Th1 and Treg were upregulated in the heart of Tgr5-/- mice at 7-day post-MI. These results suggested TGR5 modulates CD4+ T cell functions and subsets distribution in the heart, and plays protective roles in myocardial infarction.