2018/07/02 by Kohsuke Shirakawa, Jin Endo, Masaharu Kataoka +10 · 26 citations
Medicine · Immunology and Microbiology · #Cardiac Fibrosis and Remodeling #Galectins and Cancer Biology #Tissue Engineering and Regenerative Medicine
paper · doi:10.1161/circulationaha.118.035047
Background: Both osteopontin (OPN) and galectin-3 have been implicated in phagocytic clearance of dead cells and reparative fibrosis during wound healing. CD206 + macrophages are involved in tissue repair through phagocytosis and fibrosis after myocardial infarction (MI). However, the relationship among OPN, galectin-3, and macrophage polarization in the context of MI remains unclear. Methods: The time course of Spp1 (encoding OPN) expression in the heart after MI showed a strong activation of Spp1 on day 3 after MI. To identify where in the body and in which cells the transcriptional activity of Spp1 increased after MI, we analyzed EGFP (enhanced green fluorescent protein)- Spp1 knockin reporter mice on day 3 after MI. Results: The transcriptional activity of Spp1 increased only in CD206 + macrophages in the infarct myocardium, and most of CD206 + macrophages have strong transcriptional activation of Spp1 after MI. The temporal expression pattern of Lgal3 (encoding galectin-3) in cardiac macrophages after MI was similar to that of Spp1 , and OPN is almost exclusively produced by galectin-3 hi CD206 + macrophages. Although both interleukin (IL)–4 and IL-10 were reported to promote CD206 + macrophage-mediated cardiac repair after MI, IL-10– but not IL-4–stimulated CD11b + Ly6G − cells could differentiate into OPN-producing galectin-3 hi CD206 + macrophages and showed enhanced phagocytic ability. Inhibition of STAT3 tyrosine phosphorylation suppressed IL-10–induced expression of intracellular galectin-3 and transcriptional activation of Spp1. Knockdown of galectin-3 suppressed their ability to differentiate into OPN-producing cells, but not STAT3 activation. The tyrosine phosphorylation of STAT3 and the appearance rate of galectin-3 hi CD206 + cells on cardiac CD11b + Ly6G − cells in Spp1 knockout mice were the same as those in wild-type mice. Spp1 knockout mice showed vulnerability to developing post-MI left ventricular chamber dilatation and the terminal deoxynucleo-tidyltransferase 2‘-Deoxyuridine-5‘-triphosphate nick-end labeling (TUNEL)–positive cells in the infarcted myocardium after MI remained higher in number in Spp1 knockout mice than in wild-type mice. Conclusions: OPN is almost exclusively produced by galectin-3 hi CD206 + macrophages, which specifically appear in the infarct myocardium after MI. The IL-10–STAT3–galectin-3 axis is essential for OPN-producing reparative macrophage polarization after myocardial infarction, and these macrophages contribute to tissue repair by promoting fibrosis and clearance of apoptotic cells. These results suggest that galectin-3 may contribute to reparative fibrosis in the infarct myocardium by controlling OPN levels.