Dr. Koon’s research is focused on the roles of antimicrobial peptide cathelicidin in inflammatory bowel disease, intestinal infection, colon cancer, obesity, and diabetes. Cathelicidin is a natural endogenous antimicrobial peptide that is protective to host as a part of the innate immune system. Dr. Koon’s laboratory was the first to show the anti-inflammatory effects of cathelicidin in C. difficile infection in mice and C. difficile toxin A and B in immune cells and epithelial cells. We are exploring how to toxin-mediated apoptosis and necrosis via the intervention of receptor molecules, cytoskeleton, and signaling molecules using primary human cells, 3D intestinal organoid model, and molecular studies.
Cathelicidin mediates various signaling pathways that are protective to intestinal inflammation and stricture formation. Recently, we found that cathelicidin mimic CSA13 could alter intestinal microbiota that may help inhibit the development of C. difficile infection and T-cell transfer mediated colitis in mice. Cathelicidin may promote protective bacterial species that produce anti-inflammatory substances and protect the host from intestinal infection and inflammation. We are exploring how these novel bacterial species exert their protective effect using metabolomics and gnotobiotic approaches.
Cathelicidin suppresses fibroblast activity that further inhibits colonic tumor growth. This interaction involves the coordination of epithelial cells, mesenchymal cells, and immune systems in the intestine and establishes a new direction of research in digestive diseases across various functional systems in the body.
Dr. Koon is interested in studying the role of cathelicidin and other antimicrobial compounds in the development of obesity and diabetes. Cathelicidin inhibits obesity and fatty liver disease in high-fat diet-treated diabetic animals. We are now investigating the functions of cathelicidin receptor FPRL1 in various conditions.
Cathelicidin may also be used to indicate disease activity. Cathelicidin in circulating blood and colonic tissues correlate with the clinical and endoscopic disease activity in inflammatory bowel disease patients. Circulating cathelicidin levels increase with body mass indices of non-diabetic and prediabetic obese patients, suggesting the link between cathelicidin expression and obesity. Cathelicidin may be a novel biomarker for autoimmune and metabolic diseases.
Dr. Koon received master and PhD degrees from the University of Hong Kong. He then completed his postdoctoral training in basic gastroenterology research at the Beth Israel Deaconess Medical Center of Harvard Medical School in Boston. He is an associate professor of UCLA Division of Digestive Diseases as well as a member of UCLA IBD Center, UCLA Microbiome Center, and American Gastroenterological Association. Dr. Koon’s laboratory is located at the Center for Health Sciences Building. He has a team of three undergraduate research students and one full-time postdoctoral researcher. Dr. Koon has published 34 peer-reviewed manuscripts. Dr. Koon’s projects are currently funded by CCFA and NIH grants.