Defective Mer Receptor Tyrosine Kinase Signaling in Bone Marrow Cells Promotes Apoptotic Cell Accumulation and Accelerates Atherosclerosis

OBJECTIVE: To study the role of Mer receptor tyrosine kinase (mertk) in atherosclerosis. METHODS AND RESULTS: We irradiated and reconstituted atherosclerosis-susceptible C57Bl/6 low-density lipoprotein receptor-deficient female mice (ldlr(-/-)) with either a mertk(+/+) or mertk(-/-) (tyrosine kinase-defective mertk) bone marrow. The mice were put on high-fat diet for either 8 or 15 weeks. Mertk deficiency led to increased accumulation of apoptotic cells within the lesions, promoted a proinflammatory immune response, and accelerated lesion development. CONCLUSIONS: Mertk expression by bone marrow-derived cells is required for the disposal of apoptotic cells and controls lesion development and inflammation.