The Interplay Between Exosomes and Gut Microbiota in Neuroinflammation: A New Frontier in Alzheimer's Disease

Alzheimer's disease (AD) is a complex neurodegenerative condition that is characterized by the accumulation of amyloid-β, the hyperphosphorylation of tau, and persistent neuroinflammation. However, these hallmarks alone do not fully capture the intricacies of AD pathology, thus necessitating the investigation of emerging mechanisms and innovative tools. Exosomes (nanoscale vesicles involved in cell communication and immune modulation) have emerged as pivotal cellular vehicles due to their dual role-both in the propagation of pathological proteins and the regulation of inflammatory responses. Furthermore, these vesicles have been demonstrated to play a crucial role in the mediation of the effects of microbiota-derived metabolites and the reflection of systemic influences such as dysbiosis, thereby establishing a link between the gut-brain axis and the progression of AD. A comprehensive narrative literature review was conducted using the following databases: ScienceDirect, Scopus, Wiley, Web of Science, Medline, and PubMed, covering studies published between 2015 and 2025. Inclusion and exclusion criteria were established to select research addressing exosomal biogenesis, their functional and diagnosis role, their therapeutic potential, and the emerging evidence on microbiota-exosome interplay in Alzheimer's disease. Exosomes have been identified as integral mediators of intercellular communication, reflecting the molecular state of the central nervous system. These particles have been shown to promote the propagation of pathological proteins, modulate neuroinflammatory responses, and serve as non-invasive biomarkers due to their detectability in peripheral fluids. Advances in exosomal engineering and microbiome-based interventions underscore the potential for targeting systemic and CNS-specific mechanisms to develop integrative therapies for AD. Exosomes present a promising approach for the early diagnosis and personalized treatment of Alzheimer's disease. However, methodological challenges and ongoing controversies, including those related to the influence of systemic factors such as dysbiosis, necessitate multidisciplinary research to optimize and standardize these strategies.