LYVE1 (lymphatic vessel endothelial hyaluronan receptor 1) functions as a hyaluronan-binding receptor that plays critical roles in tissue homeostasis and immune regulation. The protein serves as a marker for specific tissue-resident macrophage populations across multiple organs, including LYVE1+ parenchymal border macrophages in the brain that regulate cerebrospinal fluid flow dynamics 1, and septal adipose tissue macrophages that control adipocyte stem cell differentiation 2. LYVE1+ macrophages represent one of three conserved tissue-resident macrophage subsets found across organs, characterized by self-renewal with minimal monocyte input and early embryonic origins 3. Mechanistically, LYVE1 mediates hyaluronan-dependent cellular interactions, including facilitating leukocyte adhesion and migration through lymphatic endothelium, and enabling macrophage-smooth muscle cell communication via hyaluronan matrix engagement 4. In disease contexts, LYVE1+ macrophages demonstrate both protective and pathological roles - they are atheroprotective in cardiovascular disease 5, but can be co-opted by tumors where LYVE1 serves as an osteopontin receptor promoting immunosuppressive tumor-associated macrophage proliferation 6. The receptor also contributes to tissue repair processes, with efferocytosis pathways involving LYVE1+ macrophages being critical for proper wound healing 7.