Macrophage scavenger receptor 1 (MSR1) (MSR1)

Macrophage scavenger receptor 1 (MSR1), also known as CD204 or SR-A, is a trimeric integral membrane glycoprotein primarily expressed on the surface of mature macrophages and certain dendritic cells [1, 2]. It functions as a pattern recognition receptor (PRR) capable of binding a broad range of polyanionic ligands, including modified low-density lipoproteins (e.g., acetylated LDL), bacterial surface components (e.g., lipopolysaccharide and lipoteichoic acid), and apoptotic cells [5, 11, 12]. Biologically, MSR1 is central to the innate immune response, mediating the phagocytosis of pathogens and the clearance of metabolic waste [1, 15]. In disease, it plays a dichotomous role; it is implicated in the pathogenesis of atherosclerosis by promoting the formation of lipid-laden foam cells, yet it also protects against endotoxic shock by scavenging circulating toxins [12, 15, 17]. In oncology, MSR1 is highly expressed on tumor-associated macrophages (TAMs) and is often associated with an immunosuppressive M2-like phenotype, making it a potential target for cancer immunotherapy and a prognostic biomarker [4, 21]. Therapeutic strategies currently focus on exploiting its high endocytic capacity for the targeted delivery of drugs to macrophages or modulating its activity to treat inflammatory and metabolic disorders [13, 14].

Other names

CD204Scavenger receptor class A member 1SCARA1SR-ASRAMacrophage scavenger receptor types I and IIMacrophage acetylated LDL receptor I and II

MSR1 acts as a multi-ligand receptor that mediates the internalization of polyanionic macromolecules via endocytosis and phagocytosis [1, 5]. In therapeutic contexts, its high endocytic capacity is exploited for the targeted delivery of drug-loaded carriers (e.g., dextran sulfate conjugates) specifically to activated macrophages [13, 14]. It also modulates inflammatory signaling by interacting with TRAF6 to inhibit TLR4-mediated NF-κB activation [1].