Microbial membrane vesicles and the intestinal epithelium: a crosstalk in health and disease

The intestinal epithelium maintains a critical dialogue with the gut microbiota. A key mechanism in this communication is the release of bacterial membrane vesicles (MVs), which act as functional carriers of bioactive cargo. This review explores the central role of MVs in mediating the crosstalk between the gut microbiota and the intestinal epithelium. We summarize the biogenesis of Gram-negative outer membrane vesicles (OMVs) and Gram-positive cytoplasmic membrane vesicles (CMVs) and detail the molecular pathways of their interaction with host intestinal epithelial cells, including endocytic uptake and pattern recognition receptor signaling. We then discuss the dual role of this communication: MVs from commensal bacteria are crucial for maintaining intestinal homeostasis by enhancing barrier integrity and modulating immune responses, while MVs from pathogenic bacteria contribute to diseases like inflammatory bowel disease (IBD) and colorectal cancer (CRC) by delivering virulence factors and promoting inflammation. Finally, we critically evaluate the emerging potential of MVs as non-invasive diagnostic biomarkers and as engineered therapeutic platforms for targeted drug delivery and vaccination, while highlighting the significant translational challenges that remain.