Abstract 211: Regulatory T cells improve healing after myocardial infarction

Abstract

Background: The proinflammatory activation of innate immunity by myocardial ischemic injury has been recognized for long time. Our recent data have indicated that activation of CD4+ T cells, presumably by auto-antigen recognition, is a prerequisite for formation of a stable scar and prevention from left ventricular dilation after experimental myocardial infarction in mice. We here hypothesized that regulatory CD4+CD25+Foxp3+CD4+ T cells might improve left ventricular wound healing and prevent from adverse remodeling after myocardial infarction. Results: Experimental myocardial infarction in mice induced the proliferation and activation of CD4+CD25+Foxp3+ regulatory T cells, as demonstrated by intracellular expression of the Ikaros family transcription factor Helios, in heart draining lymph nodes. Pretreatment of mice with an anti-CD25 antibody before myocardial infarction efficiently depleted CD4+CD25+Foxp3+ regulatory T cells and increased mortality after myocardial infarction as compared to mice treated with an isotype-matched control antibody of irrelevant specificity, i.e., 25% survival in anti-CD25 treated mice vs. 55,9% survival in control antibody treated animals. Therapeutic activation of regulatory CD4+CD25+Foxp3+ T cells by a superagonistic anti-CD28 antibody (CD28-SA) applied at day 2 after myocardial infarction prevented, compared to mice treated with an isotype-matched control antibody, from left ventricular rupture and resulted in improved survival (47.1% survival in the control group vs. 76.6% survival in the CD28-SA treated group). CD28-SA treatment lead to expansion of CD4+CD25+Foxp3+ T-cells in the peripheral blood and increased their frequency in the infarcted myocardium. This was associated with increased expression of several molecules known to facilitate wound healing by promoting the formation of a stable scar such as osteopontin and coagulation factor XIII. Conclusion: CD4+CD25+Foxp3+ regulatory T-cells are a prerequisite for proper myocardial wound healing and can be therapeutically activated to improve outcome after experimental myocardial infarction.