Targeting Endothelial CD146 Attenuates Colitis and Prevents Colitis-Associated Carcinogenesis

Recently, enhanced CD146 expression was reported on endothelial cells in intestinal biopsies from patients with inflammatory bowel disease. However, the underlying mechanism remains unknown. Here, we found that overexpressed endothelial CD146 promoted the inflammatory responses in inflammatory bowel disease, which further potentiated the occurrence of colitis-associated colorectal carcinogenesis. Eliminating endothelial CD146 by conditional knockout significantly ameliorated the severity of inflammation in two different murine models of colitis, and decreased tumor incidence and tumor progression in a murine model of colitis-associated colorectal carcinogenesis. Mechanistic study showed that cytokine tumor necrosis factor-alpha (TNF-alpha) up-regulated the expression of endothelial CD146 through NF-kappa B transactivation. In turn, the enhanced endothelial CD146 expression promoted both angiogenesis and proinflammatory leukocyte extravasations, contributing to inflammation. Using an anti-CD146 antibody, AA98, alone or together with an anti-TNF-alpha antibody significantly attenuated colitis and prevented colitis-associated colorectal carcinogenesis in mice. Our study provides the first evidence that CD146 plays a dual role on endothelium, facilitating leukocyte extravasations and angiogenesis, thus promoting inflammation. This finding not only reveals the function and regulating mechanism of CD146 in inflammatory bowel disease, but also provides a promising therapeutic strategy for treating inflammatory bowel disease and preventing colitis-associated colorectal carcinogenesis.