Folate Receptor Positive Macrophages: Cellular Targets for Imaging and Therapy of Inflammatory and Autoimmune Diseases

Abstract

FR beta constitutes a unique and selective marker for activated human monocytes and macrophages. Based on numerous criteria, most FR+ macrophages appear to be highly inflammatory and important in the development/maintenance of many inflammatory and autoimmune diseases, however, some appear to be activated and anti-inflammatory. Inflammatory pathologies in which FR+ macrophages are commonly enriched include rheumatoid arthritis, Crohn's disease, atherosclerosis, sarcoidosis, glomerulonephritis, osteoarthritis, organ transplant rejection, ulcerative colitis, Sjogren's syndrome, diabetes, ischemia/reperfusion injury, impact trauma, microbial infection, prosthesis osteolysis, liver steatosis, and multiple sclerosis. Folate-targeted imaging agents have proven useful in identifying, localizing, and quantifying sites of inflammation in both human patients and animal models of the above diseases. Folate-targeted therapeutic agents offer great promise for the development of highly potent, nontoxic treatment modalities for the same diseases.