Loss of Angptl4 Protects Mice from Intestinal Colitis and Tumorigenesis with Alternative Activation of Macrophages.

Angiopoietin-like 4 (Angptl4) is a secreted glycoprotein involved in the regulation of various homeostatic and disease processes. In the intestine, prior studies have suggested protective roles for Angptl4 in inflammation using Angptl4 knockout mouse models; however, phenotypic variability-such as perinatal lethality and intestinal inflammation accompanied by lymphatic defects in only a subset of animals-has complicated the interpretation of its role in intestinal pathogenesis. In this study, the impact of Angptl4 deficiency was examined using a subset of Angptl4 knockout mice that survive postnatally without overt abnormalities. It was found that loss of Angptl4 confers protection against colitis and colitis-associated colorectal tumorigenesis. These protective effects were associated with the alternative activation of anti-inflammatory M2-like macrophages. Similarly, in a genetic model of intestinal tumorigenesis, Angptl4 deficiency resulted in reduced tumor burden and attenuated inflammation, accompanied by increased M2-like macrophages. Analysis of human colorectal cancer data sets further revealed that low ANGPTL4 expression is associated with improved survival outcomes as well as reduced expression of inflammation-related marker genes. Collectively, the findings uncover a previously unrecognized protective effect of Angptl4 deficiency against intestinal pathogenesis via anti-inflammatory mechanisms, suggesting Angptl4 as a potential therapeutic target and prognostic biomarker for colorectal cancer and inflammatory bowel disease.