Requirements for apoptotic cell contact in regulation of macrophage responses. J Immunol 2006 Sep 15;177(6):4047-54
Date
09/05/2006Pubmed ID
16951368DOI
10.4049/jimmunol.177.6.4047Scopus ID
2-s2.0-33748501056 (requires institutional sign-in at Scopus site) 122 CitationsAbstract
An important consequence of macrophage engulfment of apoptotic cells is suppression of inflammatory responses, which was first defined by assay of TNF-alpha release stimulated by LPS. These effects are apparently mediated in part by paracrine effects of TGF-beta released by the subset of stimulated macrophages that ingest apoptotic cells, which suppresses neighboring cells. However, the apoptotic cell-derived signal that stimulates TGF-beta release, and the nature of any additional signals required for the anti-inflammatory response remain poorly defined. In this study, we investigate the requirements for apoptotic cell engagement of macrophage surface receptors in these responses. We show that the apoptotic cell receptors CD36 and alphavbeta3 contribute to apoptotic cell phagocytosis by mouse macrophages, but are not essential for anti-inflammatory responses, suggesting that the mechanisms of response and phagocytosis are separate. In further defining requirements for response, we confirm the importance of TGF-beta in suppression by apoptotic cells, and identify an additional level of control of these effects. We show that LPS-stimulated mouse macrophage TNF-alpha release is only suppressed if macrophages have first contacted apoptotic cells, and hence, bystander macrophages are refractory to TGF-beta released by phagocytosing macrophages. We conclude that the profound suppression of LPS-driven TNF-alpha release by macrophage populations requires hitherto obscure contact-dependent licensing of macrophage responsiveness to TGF-beta by apoptotic cells.
Author List
Lucas M, Stuart LM, Zhang A, Hodivala-Dilke K, Febbraio M, Silverstein R, Savill J, Lacy-Hulbert AAuthor
Roy L. Silverstein MD Professor in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsApoptosis
Cell Communication
Cells, Cultured
Humans
Macrophages
Mice
Mice, Inbred BALB C
Mice, Inbred C57BL
Mice, Knockout
Phagocytosis
