Caffeic Acid Protects Against Ulcerative Colitis via Inhibiting Mitochondrial Apoptosis and Immune Overactivation in Drosophila

Minghui Xiu,1,2,* Botong Li,3,* Li He,1 Yan Shi,3 Yongxuan Zhang,1 Shihong Zhou,1 Yongqi Liu,2,3 Ningbo Wang,4 Jianzheng He2,3,5 1College of Public Health, Gansu University of Chinese Medicine, Lanzhou City, Gansu Province, People’s Republic of China; 2Key Laboratory of Dunhuang Medicine, Ministry of Education, Lanzhou City, Gansu Province, People’s Republic of China; 3Provincial-Level Key Laboratory for Molecular Medicine of Major Diseases and the Prevention and Treatment with Traditional Chinese Medicine Research in Gansu Colleges and University, Gansu University of Chinese Medicine, Lanzhou City, Gansu Province, People’s Republic of China; 4Tibetan Medical College, Qinghai University, Xining City, Qinghai Province, People’s Republic of China; 5Research and Experimental Center, Gansu University of Chinese Medicine, Lanzhou City, Gansu Province, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jianzheng He, Email [email protected]: Ulcerative colitis (UC) is a chronic intestinal inflammation that is prone to relapse and is difficult to fully recover; therefore, there is a need for safer alternative treatments. Caffeic acid (CA) is a natural polyphenolic compound that has antioxidant and anti-inflammatory properties. However, the beneficial effects and mechanisms of action of CA in UC remain unclear.Purpose: This study evaluated the protective effect of CA against dextran sulfate sodium (DSS)-induced intestinal injury in Drosophila melanogaster model.Results: Oral administration of CA significantly reduced body damage in UC flies, improved their survival rate, restored damaged digestion, and improved locomotion. CA supplementation significantly alleviated intestinal damage in UC flies by restoring excretion balance, repairing intestinal atrophy, improving acid-base balance imbalance, inhibiting intestinal structural destruction, inhibiting intestinal epithelial cell death and intestinal stem cell (ISC) excessive proliferation, and reducing the number of harmful bacteria. Mechanistic studies found that CA significantly reduced the expression of Toll and Imd pathway genes (including Myd88, Dif, PGRP-LC, Imd, Rel, and Dpt), reduced ROS levels and the expression of apoptosis-related genes (Debcl, Cyt-c-p, DrlCE, Dronc, and Dark), and increased ATP and MFN2 levels.Conclusion: CA alleviated intestinal damage mainly by inhibiting the Toll and Imd signaling pathways and inhibiting apoptosis mediated by mitochondrial damage. These findings suggest that CA holds promise as a potential therapeutic for UC treatment. Keywords: ulcerative colitis, caffeic acid, toll and Imd pathways, apoptosis, Drosophila melanogaster