Professional phagocytes (such as macrophages) and non-professional phagocytes (such as epithelial cells) clear billions of apoptotic cells and particles on a daily basis. Since these phagocytes reside in proximity in most tissues, whether cross-communication exists between them during cell clearance, and how this might impact inflammation are not known. Here, we show that macrophages, via the release of a soluble growth factor and microvesicles, redirect the type of particles engulfed by non-professional phagocytes and influence their inflammatory response. During apoptotic cell engulfment or in response to inflammation-associated cytokines, macrophages released insulin-like growth factor 1 (IGF-1). The binding of IGF-1 to its receptor on non-professional phagocytes redirected their phagocytosis, such that uptake of larger apoptotic cells was dampened while engulfment of microvesicles was enhanced. Macrophages were refractory to this IGF-1 mediated engulfment modulation. Macrophages also released microvesicles, whose uptake by epithelial cells, enhanced by IGF-1, led to decreased inflammatory responses by epithelial cells. Consistent with these observations, deletion of IGF-1 receptor in airway epithelial cells led to exacerbated lung inflammation after allergen exposure. These genetic and functional studies reveal a novel IGF-1 and microvesicle-dependent communication between macrophages and epithelial cells that can critically influence the magnitude of tissue inflammation in vivo.Les phagocytes professionnels (tels que les macrophages) et les phagocytes non professionnels (tels que des cellules épithéliales) éliminent des milliards de cellules apoptotiques et de particules de façon quotidienne. Étant donné que ces phagocytes résident à proximité dans la plupart des tissus, l'existence d'une communication croisée entre ceux-ci pendant la clairance cellulaire, et les éventuelles conséquences sur l'inflammation ne sont pas connues. Selon la présente invention, nous
