Fig. 2
From: The physiology of foamy phagocytes in multiple sclerosis
Endocytosis of myelin by phagocytes. Myelin internalization by phagocytes is dependent on the receptor repertoire as well as various intrinsic and extrinsic factors. While scavenger receptors (SR-AI/II and collectin placenta 1 (CL-P1)), Fc receptors, complement receptors (CR3), mer tyrosine kinase (MerTK), and low-density lipoprotein receptor-related protein 1 (LRP1) positively regulate the uptake of myelin, ligation of signal regulatory protein α (SIRPα) inhibits myelin uptake. Cell intrinsic and extrinsic factors, such as phagocyte polarization (M1- or M2-like), phagocyte ontogeny, (hematopoietic stem cells or yolk-sac progenitors), cellular aging, and myelin composition and modifications, can impact the capacity of phagocytes to internalize myelin