Core Insights - The research conducted by the Shanghai Institute of Nutrition and Health reveals the molecular mechanism of APOL9 protein's specific binding to gut microbiota, which plays a crucial role in maintaining intestinal immune homeostasis [1][2] - APOL9 protein acts as a "bacterial diplomat," inducing specific bacteria to release outer membrane vesicles (OMVs) that enhance the host's immune response [1][2] Group 1: Research Findings - The study published in the journal "Nature" highlights that APOL9 does not kill target bacteria but instead promotes the release of OMVs, which are rich in bacterial molecules that can be captured by the host immune system [1] - OMVs activate the interferon-γ signaling pathway and increase the expression of MHC-II molecules on intestinal cells, leading to the training of a specific type of T cells that maintain intestinal immune stability [1][2] Group 2: Experimental Validation - To validate the physiological function of APOL9, the research team created APOL9 gene knockout mice, which showed uncontrolled bacterial spread and increased mortality when infected with Salmonella [2] - Supplementing these knockout mice with OMVs significantly improved infection symptoms and enhanced immune responses, demonstrating the active role of host proteins in shaping beneficial immune reactions [2]

Core Insights - The research reveals a new mechanism of interaction between the host and gut microbiota, specifically through the APOL9 protein, which acts as a "smart identifier" for specific bacteria [1][3][16] - This study indicates that the gut is not only a site for digestion but also a crucial part of a sophisticated immune network between the host and microorganisms [3][16] Group 1: Research Findings - The APOL9 protein can precisely identify a type of bacteria by recognizing specific lipid markers on their cell membranes, functioning like a "scanner reading a barcode" [3][10] - APOL9 does not kill bacteria directly but promotes the release of nanoscale "information capsules" known as outer membrane vesicles (OMVs), which communicate with the immune system [13][16] - The study establishes that the host can actively shape the gut microbiome through molecular "dialogue," leading to a dynamic balance in gut ecology [16][17] Group 2: Implications for Health - The findings suggest potential new therapeutic approaches for diseases related to gut microbiome imbalance, such as inflammatory bowel disease and metabolic syndrome [17][18] - The conserved function of human APOL2 indicates that this mechanism may have cross-species applicability, laying the groundwork for translational medical research [17][18] Group 3: Research Background - The research team, led by Qian Youcun and Song Xinyang, has been working on this project for over a decade, highlighting the collaborative nature of scientific research [18][19] - The study's progress was facilitated by advancements in microbial editing technologies and a supportive research environment [19]