Abstract C037: Bile acid modulation of immune cell interactions in the colonic microenvironment

Abstract

Abstract Colorectal cancer (CRC) is the third most frequent cancer in both women and men, particularly among African Americans (AA). Factors such as ethnicity group, gut microbiota, and Western diet play a significant role in CRC development. However, the impact of ethnicity on the immunological mechanisms involved in CRC is poorly understood. In our study, we collected stool and serum samples from high-risk and low-risk AA and NHW subjects to analyze the fecal bile acid metabolome. We found that certain bile acid isoforms, particularly in allo-bile acids, were significantly reduced in the stool compared to Non-Hispanic White (NHW) females. Clinical mucosal RNA data we generated via the NanoString nCounter platform, revealed in both AA and NHW low-risk female groups, the expression of FoxP3, correlated with immune checkpoints including PDCD1, IDO1, CTLA4 and LAG3 were lowered. Recent findings suggest that allo-bile acids influence the balance between pro-inflammatory TH17 cells and anti-inflammatory Tregs through specific signaling pathways. Based on our data and existing literature, we propose that bacterial-derived allo-bile acids modulate interactions between other myeloid-lineage immune cells, thereby affecting the inflammatory environment of the colon and potentially influencing CRC development. Citation Format: Hanchu Dai, Patricia Wolf, Ece Mutlu, Lisa Tussing-Humphreys, Jason Ridlon, Rex Gaskins. Bile acid modulation of immune cell interactions in the colonic microenvironment [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C037.