Short-term S100A8/A9 Blockade Promotes Cardiac Neovascularization after Myocardial Infarction.

Acute-phase inhibition of the pro-inflammatory alarmin S100A8/A9 improves cardiac function post-myocardial infarction (MI), but the mechanisms underlying the long-term benefits of this short-term treatment remain to be elucidated. Here, we assessed the effects of S100A8/A9 blockade with the small-molecule inhibitor ABR-238901 on myocardial neovascularization in mice with induced MI. The treatment significantly reduced S100A9 and increased neovascularization in the myocardium, assessed by CD31 staining. Proteomic analysis by mass-spectrometry showed strong myocardial upregulation of the pro-angiogenic proteins filamin A (~ 10-fold) and reticulon 4 (~ 5-fold), and downregulation of the anti-angiogenic proteins Ras homolog gene family member A (RhoA, ~ 4.7-fold), neutrophilic granule protein (Ngp, ~ 4.0-fold), and cathelicidin antimicrobial peptide (Camp, ~ 4.4-fold) versus controls. In-vitro, ABR-238901 protected against apoptosis induced by recombinant human S100A8/A9 in human umbilical vein endothelial cells (HUVECs). In conclusion, S100A8/A9 blockade promotes post-MI myocardial neovascularization by favorably modulating pro-angiogenic proteins in the myocardium and by inhibiting endothelial cell apoptosis.