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, 100ng/ml) or peptidoglycan (PGN, 20microg/ml) in the presence or in the absence of apoptotic cells. After 24h, mononuclear phagocytes from patients with acute coronary syndromes produced more TNFalpha 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 <3mg/l than in patients with CRP levels >3mg/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.