| First Author | Hilgendorf I | Year | 2014 |
| Journal | Circ Res | Volume | 114 |
| Issue | 10 | Pages | 1611-22 |
| PubMed ID | 24625784 | Mgi Jnum | J:246860 |
| Mgi Id | MGI:5921608 | Doi | 10.1161/CIRCRESAHA.114.303204 |
| Citation | Hilgendorf I, et al. (2014) Ly-6Chigh monocytes depend on Nr4a1 to balance both inflammatory and reparative phases in the infarcted myocardium. Circ Res 114(10):1611-22 |
| abstractText | RATIONALE: Healing after myocardial infarction involves the biphasic accumulation of inflammatory lymphocyte antigen 6C (Ly-6C)(high) and reparative Ly-6C(low) monocytes/macrophages (Mo/MPhi). According to 1 model, Mo/MPhi heterogeneity in the heart originates in the blood and involves the sequential recruitment of distinct monocyte subsets that differentiate to distinct macrophages. Alternatively, heterogeneity may arise in tissue from 1 circulating subset via local macrophage differentiation and polarization. The orphan nuclear hormone receptor, nuclear receptor subfamily 4, group a, member 1 (Nr4a1), is essential to Ly-6C(low) monocyte production but dispensable to Ly-6C(low) macrophage differentiation; dependence on Nr4a1 can thus discriminate between systemic and local origins of macrophage heterogeneity. OBJECTIVE: This study tested the role of Nr4a1 in myocardial infarction in the context of the 2 Mo/MPhi accumulation scenarios. METHODS AND RESULTS: We show that Ly-6C(high) monocytes infiltrate the infarcted myocardium and, unlike Ly-6C(low) monocytes, differentiate to cardiac macrophages. In the early, inflammatory phase of acute myocardial ischemic injury, Ly-6C(high) monocytes accrue in response to a brief C-C chemokine ligand 2 burst. In the second, reparative phase, accumulated Ly-6C(high) monocytes give rise to reparative Ly-6C(low) F4/80(high) macrophages that proliferate locally. In the absence of Nr4a1, Ly-6C(high) monocytes express heightened levels of C-C chemokine receptor 2 on their surface, avidly infiltrate the myocardium, and differentiate to abnormally inflammatory macrophages, which results in defective healing and compromised heart function. CONCLUSIONS: Ly-6C(high) monocytes orchestrate both inflammatory and reparative phases during myocardial infarction and depend on Nr4a1 to limit their influx and inflammatory cytokine expression. |
