CD73 on T-Cells Orchestrates Cardiac Wound Healing After Myocardial Infarction by Purinergic Metabolic Reprogramming
Background—T-cells are required for proper healing after myocardial infarction. The mechanism of their beneficial action, however, is unknown. The pro-inflammatory "danger signal" adenosine triphosphate (ATP), released from damaged cells, is degraded by the ectonucleotidases CD39 and CD73 to the anti-inflammatory mediator adenosine. Here, we investigate the contribution of CD73-derived adenosine produced by T-cells to cardiac remodeling after ischemia/reperfusion and define its mechanism of action.
Methods—Myocardial ischemia (50 min /reperfusion) was induced in global CD73-/- and CD4-CD73-/- mice. Tissue injury, T-cell purinergic signaling, cytokines and cardiac function (MRT at 9.4 T over four weeks) were analyzed.
Results—Changes in functional parameters of CD4-CD73-/- mice were identical to global CD73 knockouts. T-cells infiltrating the injured heart significantly upregulated at the gene (qPCR) and protein levels (enzymatic activity) critical transporters and enzymes (Cx43, Cx37, Panx1, ENT1, CD39, CD73, ENNP 1+3, CD157, CD38) for the accelerated release and hydrolysis of ATP, cAMP, AMP and NAD to adenosine. Surprisingly, lack of CD39 on T-cells (from CD39-/- mice) did not alter ATP hydrolysis and very likely involves pyrophosphatases (ENNP 1+3). Circulating T cells predominantly expressed A2aR transcripts. Following MI, A2bR transcription was induced in both T cells and myeloid cells in the heart. Thus A2aR and A2bR signaling may both contribute to myocardial responses after MI. In the case of T-cells, this was associated with an accelerated secretion of proinflammatory and profibrotic cytokines (Il-2, IFN-γ and IL-17) when CD73 was lacking. Cytokine production by T-cells from peripheral lymph nodes was inhibited by A2aR activation (CGS-21680). The A2bR agonist BAY 60-6583 showed off-target effects. The adenosine receptor agonist NECA inhibited IFN-γ and stimulated IL-6 production, each of which was antagonized by a specific A2bR antagonist (PSB-603).
Conclusions—This work demonstrates that CD73 on T-cells plays a crucial role in the cardiac wound healing process after MI. The underlying mechanism involves a profound increase in the hydrolysis of ATP/NAD and AMP, due primarily tothe upregulation of pyrophosphatases and CD73. We also define A2bR/A2aR-mediated autacoid feed-back inhibition of proinflammatory/ profibrotic cytokines by T-cell-derived CD73.
- Received May 6, 2016.
- Revision received April 3, 2017.
- Accepted April 6, 2017.