MFG-E8 mediates primary phagocytosis of viable neurons during neuroinflammation

M Fricker, JJ Neher, JW Zhao, C Théry… - Journal of …, 2012 - Soc Neuroscience
M Fricker, JJ Neher, JW Zhao, C Théry, AM Tolkovsky, GC Brown
Journal of Neuroscience, 2012Soc Neuroscience
Milk-fat globule EGF factor-8 (MFG-E8, SED1, lactadherin) is known to mediate the
phagocytic removal of apoptotic cells by bridging phosphatidylserine (PS)-exposing cells
and the vitronectin receptor (VR) on phagocytes. However, we show here that MFG-E8 can
mediate phagocytosis of viable neurons during neuroinflammation induced by
lipopolysaccharide (LPS), thereby causing neuronal death. In vitro, inflammatory neuronal
loss is independent of apoptotic pathways, and is inhibited by blocking the PS/MFG-E8/VR …
Milk-fat globule EGF factor-8 (MFG-E8, SED1, lactadherin) is known to mediate the phagocytic removal of apoptotic cells by bridging phosphatidylserine (PS)-exposing cells and the vitronectin receptor (VR) on phagocytes. However, we show here that MFG-E8 can mediate phagocytosis of viable neurons during neuroinflammation induced by lipopolysaccharide (LPS), thereby causing neuronal death. In vitro, inflammatory neuronal loss is independent of apoptotic pathways, and is inhibited by blocking the PS/MFG-E8/VR pathway (by adding PS blocking antibodies, annexin V, mutant MFG-E8 unable to bind VR, or VR antagonist). Neuronal loss is absent in Mfge8 knock-out cultures, but restored by adding recombinant MFG-E8, without affecting inflammation. In vivo, LPS-induced neuronal loss is reduced in the striatum of Mfge8 knock-out mice or by coinjection of an MFG-E8 receptor (VR) inhibitor into the rat striatum. Our data show that blocking MFG-E8-dependent phagocytosis preserves live neurons, implying that phagocytosis actively contributes to neuronal death during brain inflammation.
Soc Neuroscience