Rios, Francisco J. O.
Total Authors: 4
 Univ Sao Paulo, Dept Immunol, Inst Biomed Sci, BR-05508000 Sao Paulo - Brazil
 Univ Glasgow, Inst Cardiovasc & Med Sci, British Heart Fdn, Glasgow Cardiovasc Res Ctr, Glasgow G12 8TA, Lanark - Scotland
Total Affiliations: 2
Mediators of Inflammation;
Web of Science Citations:
Phagocytosis of apoptotic cells (efferocytosis) induces macrophage differentiation towards a regulatory phenotype (IL-10(high)/IL12p40(low)). CD36 is involved in the recognition of apoptotic cells (AC), and we have shown that the platelet-activating factor receptor (PAFR) is also involved. Here, we investigated the contribution of PAFR and CD36 to efferocytosis and to the establishment of a regulatory macrophage phenotype. Mice bone marrow-derived macrophages were cocultured with apoptotic thymocytes, and the phagocytic indexwas determined. Blockage of PAFRwith antagonists orCD36 with specific antibodies inhibited the phagocytosis of AC (similar to 70-80%). Using immunoprecipitation and confocal microscopy, we showed that efferocytosis increased the CD36 and PAFR colocalisation in the macrophage plasma membrane; PAFR and CD36 coimmunoprecipitated with flotillin-1, a constitutive lipid raft protein, and disruption of these membrane microdomains by methyl-beta-cyclodextrin reduced AC phagocytosis. Efferocytosis induced a pattern of cytokine production, IL-10(high)/IL-12p40(low), that is, characteristic of a regulatory phenotype. LPS potentiated the efferocytosis-induced production of IL-10, and thiswas prevented by blocking PAFR or CD36. It can be concluded that phagocytosis of apoptotic cells engages CD36 and PAFR, possibly in lipid rafts, and this is required for optimal efferocytosis and the establishment of the macrophage regulatory phenotype. (AU)