Bacterial outer membrane vesicles: A scoping review on their dual roles in immunity and disease (2020–2025)

BackgroundOuter membrane vesicles (OMVs) from Gram-negative bacteria are dynamic nanoparticles that shape host–pathogen interactions, acting as both immunostimulatory and immunosuppressive agents critical for microbial pathogenesis and therapeutic innovation.ObjectiveThis scoping review aimed to synthesize recent advancements (2020–2025) in understanding OMVs' roles in immune modulation, pathogenesis, and microbiota-immune crosstalk, as well as their potential as vaccine platforms and drug delivery systems.MethodsRelevant literature was identified through searches in PubMed, Google Scholar, and Web of Science, targeting peer-reviewed studies from 2020 to 2025. Approximately 80 were selected based on their relevance to OMV biogenesis, immune interactions, and applications in infectious diseases and cancer.ResultsOMVs activate proinflammatory pathways via pathogen-associated molecular patterns, contributing to diseases like inflammatory bowel disease and sepsis, while commensal OMVs (e.g., from Bacteroides fragilis) promote tolerogenic immunity and gut homeostasis. Diverse uptake mechanisms enable targeted delivery of virulence or regulatory factors. OMVs enhance microbiota-immune crosstalk, strengthening epithelial barriers and modulating immunity. Therapeutically, bioengineered OMVs show promise in vaccines and personalized medicine, though scalability, heterogeneity, and toxicity pose challenges.ConclusionOMVs are versatile tools bridging microbiology and immunology, with significant therapeutic potential. This review's novelty lies in its exclusive focus on Gram-negative OMVs, integrating 2020–2025 advances to address gaps in microbiota-driven immunity and bioengineered therapeutics, guiding future research in vaccine development and clinical translation.