Anti-inflammatory action of apoptotic cells in patients with acute coronary syndromes

Objectives: Atherosclerotic plaques contain both apoptotic cells and phagocytes. Apoptotic cells are known to exert an anti-inflammatory effect. Little is known on their action in patients with acute coronary syndromes. Methods and results: We challenged mononuclear phagocytes from the peripheral blood of patients with acute coronary syndromes (n = 20) and healthy controls (n = 30) with lipopolysaccharide (LPS, 100 ng/ml) or peptidoglycan (PGN, 20 mu g/ml) in the presence or in the absence of apoptotic cells. After 24 h, mononuclear phagocytes from patients with acute coronary syndromes produced more TNF alpha and IL-10 than controls; moreover, they were significantly more susceptible to the anti-inflammatory action of apoptotic cells. Apoptotic cells were more effective in ACS patients with C-reactive protein levels <3 mg/l than in patients with CRP levels >3 mg/l. Conclusions: Patients with acute coronary syndromes and low circulating C-reactive protein levels are more sensitive to the anti-inflammatory action of apoptotic cells: this suggests the existence of an enhanced anti-inflammatory feedback circuit, which could contribute to protect from plaque instability. (C) 2009 Elsevier Ireland Ltd. All rights reserved.