From trash to treasure: the role of bacterial extracellular vesicles in gut health and disease

Impact of probiotics-derived extracellular vesicles on livestock gut barrier function

Probiotic extracellular vesicles (pEVs) are biologically active nanoparticle structures that can regulate the intestinal tract through direct or indirect mechanisms. They enhance the intestinal barrier function in livestock and poultry and help alleviate intestinal diseases. The specific effects of pEVs depend on their internal functional components, including nucleic acids, proteins, lipids, and other substances. This paper presents a narrative review of the impact of pEVs on the intestinal barrier across various segments of the intestinal tract, exploring their mechanisms of action while highlighting the limitations of current research. Investigating the mechanisms through which probiotics operate via pEVs could deepen our understanding and provide a theoretical foundation for their application in livestock production.

Potential therapeutic application and mechanism of gut microbiota-derived extracellular vesicles in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine and metabolic disorder affecting women of reproductive age. The syndrome is characterized by androgen excess, ovarian dysfunction, insulin resistance (IR) and obesity, with an elevated risk of developing long-term complications, including cardiovascular disease and type 2 diabetes mellitus (T2D). The gut microbiota plays a role in the pathogenesis of PCOS by influencing the host's endocrine, metabolic and inflammatory state, as well as the gut-brain axis. Gut microbiota-derived extracellular vesicles (GMEVs) are lipid bilayer nanoparticles secreted by the gut microbiota and contain a variety of components, including proteins, lipids and nucleic acids. They serve as signaling molecules, facilitating bacterial-bacterial and bacterial-host communications. Bacterial extracellular vesicles (BEVs) affect host cells through the delivery of bioactive substances and physical interaction through membrane components, thereby participating in the regulation of metabolic, immune, and other cellular processes. Furthermore, BEVs, which are distinguished by low toxicity, high biocompatibility and stability, and the capacity to cross biological barriers, present a promising avenue for the development of novel drug delivery systems. The isolation and characterization of BEVs also facilitate the investigation of disease-specific biomarkers. Consequently, BEVs have immense potential for a range of medical research applications, including disease diagnosis and treatment. This article discusses the potential therapeutic effects and mechanisms of GMEVs in the treatment of PCOS.

Propionibacterium freudenreichii MJ2-derived extracellular vesicles inhibit RANKL-induced osteoclastogenesis and improve collagen-induced rheumatoid arthritis

Rheumatoid arthritis causes excessive bone loss by stimulating osteoclast differentiation. Extracellular vesicles are valuable disease markers, conveyors of distant cell-to-cell communication, and carriers for drug delivery. The aim of this study was to investigate the anti-osteoclastogenic effects of extracellular vesicles derived from dairy Propionibacterium freudenreichii MJ2 (PFEVs) and the improvement effect of PFEVs on collagen-induced arthritis (CIA) animal model. PFEVs were observed by scanning electron microscopy, transmission electron microscopy, nanoparticle tracking analysis, and LC-MS/MS. The inhibitory activity of PFEVs against receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast differentiation was investigated in RAW 264.7 cells. PFEVs significantly decreased the expression levels of genes and proteins related to osteoclast differentiation. PFEVs decreased RANK-RANKL binding. In a CIA mouse model, PFEVs treatment significantly reduced arthritis scores and collagen-specific immunoglobulins. PFEVs treatment also reduced pro-inflammatory cytokines and increased anti-inflammatory cytokines. The anti-inflammatory effects were confirmed by H&E staining, and PFEVs treatment inhibited osteoclastogenesis in the CIA mouse model. In conclusion, PFEVs inhibited osteoclast differentiation by inhibiting RANK-RANKL signaling, thereby decreasing the expression of osteoclast differentiation-related genes. PFEVs also improved collagen-induced arthritis by inhibiting inflammation and osteoclastogenesis.

Unveiling the Potential of Extracellular Vesicles as Biomarkers and Therapeutic Nanotools for Gastrointestinal Diseases

Extracellular vesicles (EVs), acting as inherent nanocarriers adept at transporting a range of different biological molecules such as proteins, lipids, and genetic material, exhibit diverse functions within the gastroenteric tract. In states of normal health, they participate in the upkeep of systemic and organ homeostasis. Conversely, in pathological conditions, they significantly contribute to the pathogenesis of gastrointestinal diseases (GIDs). Isolating EVs from patients' biofluids facilitates the discovery of new biomarkers that have the potential to offer a rapid, cost-effective, and non-invasive method for diagnosing and prognosing specific GIDs. Furthermore, EVs demonstrate considerable therapeutic potential as naturally targeted physiological carriers for the intercellular delivery of therapeutic cargo molecules or as nanoscale tools engineered specifically to regulate physio-pathological conditions or disease progression. Their attributes including safety, high permeability, stability, biocompatibility, low immunogenicity, and homing/tropism capabilities contribute to their promising clinical therapeutic applications. This review will delve into various examples of EVs serving as biomarkers or nanocarriers for therapeutic cargo in the context of GIDs, highlighting their clinical potential for both functional and structural gastrointestinal conditions. The versatile and advantageous properties of EVs position them as promising candidates for innovative therapeutic strategies in advancing personalized medicine approaches tailored to the gastroenteric tract, addressing both functional and structural GIDs.

Bacterial extracellular vesicles at the interface of gut microbiota and immunity

Bacterial extracellular vesicles (BEVs) are nano-sized lipid-shielded structures released by bacteria and that play an important role in intercellular communication. Their broad taxonomic origins and varying cargo compositions suggest their active participation in significant biological mechanisms. Specifically, they are involved in directly modulating microbial ecosystems, competing with other organisms, contributing to pathogenicity, and influencing the immunity of their hosts. This review examines the mechanisms that underlie the modulatory effects of BEVs on gut dynamics and immunity. Understanding how BEVs modulate microbiota composition and functional imbalances is crucial, as gut dysbiosis is implicated not only in the pathogenesis of various gastrointestinal, metabolic, and neurological diseases, but also in reducing resistance to colonization by enteric pathogens, which is particularly concerning given the current antimicrobial resistance crisis. This review summarizes recent advancements in the field of BEVs to encourage further research into these enigmatic entities. This will facilitate a better understanding of intra- and interkingdom communication phenomena and reveal promising therapeutic approaches.

Microbial Extracellular Vesicles in Host-Microbiota Interactions

Extracellular vesicles have emerged as key players in cellular communication, influencing various physiological processes and pathophysiological progression, including digestion, immune response, and tissue repairs. Recently, a class of EVs derived from microbial communities has gained significant attention due to their pivotal role in intercellular communication and their potential as biomarkers and biotherapeutic agents. Microbial EVs are membrane-bound molecules encapsulating bioactive metabolites that modulate host physiological and pathological processes. This chapter discusses the evolving history of microbiota-produced EVs, including their discovery, characterization, current research status, and their diverse mechanisms of interaction with other microbes and hosts. This review also highlights the importance of EVs in health and disease and discusses recent research that shows promising results for the therapeutic potential of EVs.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.