| First Author | Savage JC | Year | 2015 |
| Journal | J Neurosci | Volume | 35 |
| Issue | 16 | Pages | 6532-43 |
| PubMed ID | 25904803 | Mgi Jnum | J:352207 |
| Mgi Id | MGI:6822737 | Doi | 10.1523/JNEUROSCI.4586-14.2015 |
| Citation | Savage JC, et al. (2015) Nuclear receptors license phagocytosis by trem2+ myeloid cells in mouse models of Alzheimer's disease. J Neurosci 35(16):6532-43 |
| abstractText | Alzheimer's disease (AD) is characterized by a robust inflammatory response elicited by the accumulation and subsequent deposition of amyloid (Abeta) within the brain. The brain's immune cells migrate to and invest their processes within Abeta plaques but are unable to efficiently phagocytose and clear plaques from the brain. Previous studies have shown that treatment of myeloid cells with nuclear receptor agonists increases expression of phagocytosis-related genes. In this study, we elucidate a novel mechanism by which nuclear receptors act to enhance phagocytosis in the AD brain. Treatment of murine models of AD with agonists of the nuclear receptors PPARgamma, PPARdelta, LXR, and RXR stimulated microglial phagocytosis in vitro and rapidly induced the expression of the phagocytic receptors Axl and MerTK. In murine models of AD, we found that plaque-associated macrophages expressed Axl and MerTK and treatment of the cells with an RXR agonist further induced their expression, coincident with the rapid reduction in plaque burden. Further characterization of MerTK(+)/Axl(+) macrophages revealed that they also expressed the phagocytic receptor TREM2 and high levels of CD45, consistent with a peripheral origin of these cells. Importantly, in an ex vivo slice assay, nuclear receptor agonist treatment reversed the AD-related suppression of phagocytosis through a MerTK-dependent mechanism. Thus, nuclear receptor agonists increase MerTK and Axl expression on plaque-associated immune cells, consequently licensing their phagocytic activity and promoting plaque clearance. |
