Chinese researchers have published a research result in the internationally renowned academic journal Nature. This study found that the intestinal epithelial cells of mice secrete a protein called APOL9 (corresponding to APOL2 in the human body), which acts as a well-trained "bacterial diplomat" and establishes refined cooperation with specific bacteria to help maintain intestinal immune stability. People who like yogurt should not be unfamiliar with probiotics such as lactic acid bacteria. Probiotics are just a part of the vast microbiota in the gut. In the human intestine, there are trillions of microorganisms at work, some beneficial and some harmful, playing a "game of power" together. How to accurately identify "bacteria" in the intestine? According to researchers, the body deploys defense systems such as mucus barrier shields and antibacterial protein weapons through the "Great Wall" composed of intestinal epithelial cells, working together with the microbiota to maintain ecological balance. APOL9 does not directly kill bacteria, but it can promote the release of outer membrane vesicles by bacteria. These nanoscale vesicles are used to activate immune responses, significantly enhancing the intestinal defense against harmful bacteria. The Qian Youcun Research Group of the Chinese Academy of Sciences Shanghai Institute of Nutrition and Health, together with the Song Xinyang Research Group of the Center for Excellence and Innovation in Molecular Cell Science of the Chinese Academy of Sciences, revealed the above mechanism through 11 years of research. This study reveals a new paradigm: hosts do not passively tolerate microorganisms, but achieve dynamic balance of gut microbiota through active molecular "dialogue". This discovery provides a new pathway for the development of next-generation therapies that synergistically regulate microbiota immunity. Qian Youcun, a researcher at the Chinese Academy of Sciences Shanghai Institute of Nutrition and Health, said that in the future, the research team plans to further explore the function of human APOL2 protein and study how to enhance the intestinal immune barrier by regulating this pathway. Song Xinyang, a researcher at the Center for Excellence and Innovation in Molecular Cell Science of the Chinese Academy of Sciences, said in an interview that in the forefront of symbiotic microbial research, there are several laboratories in China that are world-class in the world. In this field, Chinese researchers still have the opportunity to catch up, or even surpass. (New Society)