The Immunomodulatory Properties of Extracellular Vesicles Derived from Probiotics: A Novel Approach for the Management of Gastrointestinal Diseases

Extracellular vesicles of Limosilactobacillus fermentum SLAM216 ameliorate skin symptoms of atopic dermatitis by regulating gut microbiome on serotonin metabolism

Atopic dermatitis (AD) is a globally prevalent chronic inflammatory skin disorder. Its pathogenesis remains incompletely understood, resulting in considerable therapeutic challenges. Recent studies have highlighted the significance of the interaction between AD and gut microbiome. In this study, we investigated the effects of probiotic-derived extracellular vesicles on AD. Initially, we isolated and characterized extracellular vesicles from Limosilactobacillus fermentum SLAM 216 (LF216EV) and characterized their composition through multi-omics analysis. Gene ontology (GO) and pathway analysis classified LF216EV proteins into biological processes, molecular functions, and cellular components. Importantly, specific abundance in linoleic, oleic, palmitic, sebacic, and stearic acids indicating upregulated fatty acid metabolism were observed by metabolomic analysis. Furthermore, featured lipid profiling including AcylGlcADG and ceramide were observed in LF216EV. Importantly, in an atopic dermatitis-like cell model induced by TNFα/IFNγ, LF216EV significantly modulated the expression of immune regulatory genes (TSLP, TNFα, IL-6, IL-1β, and MDC), indicating its potential functionality in atopic dermatitis. LF216EV alleviated AD-like phenotypes, such as redness, scaling/dryness, and excoriation, induced by DNCB. Histopathological analysis revealed that LF216EV decreased epidermal thickness and mast cell infiltration in the dermis. Furthermore, LF216EV administration reduced mouse scratching and depression-related behaviors, with a faster onset than the classical treatment with dexamethasone. In the quantitative real-time polymerase chain reaction (qRT-PCR) analysis, we observed a significant increase in the expression levels of htrb2c, sert, and tph-1, genes associated with serotonin, in the skin and gut of the LF216EV-treated group, along with a significant increase in the total serum serotonin levels. Gut microbiome analysis of the LF216EV-treated group revealed an altered gut microbiota profile. Correlation analysis revealed that the genera Limosilactobacillus and Desulfovibrio were associated with differences in the intestinal metabolites, including serotonin. Our findings demonstrate that LF216EV mitigates AD-like symptoms by promoting serotonin synthesis through the modulation of gut microbiota and metabolome composition.

Effect of probiotic extracellular vesicles and their applications on health and disease

Probiotics have been established to exert a positive impact on the treatment of various diseases. Indeed, these active microorganisms have garnered significant attention in recent years for their potential to prevent and treat illnesses. Their beneficial effects have been hypothesized to be linked to their released extracellular vesicles. These nanoscale structures, secreted during the growth and metabolism of probiotics, possess favorable biocompatibility and targeting properties, thereby promoting intercellular material transport and signaling. This article aimed to review the bioactive components and functions of these probiotics vesicles, highlighting their role in the treatment of various diseases and discussing their potential future applications. By exploring the mechanisms of probiotic extracellular vesicles in disease development, this review aimed to provide a theoretical reference for further research on their therapeutic potential. © 2025 Society of Chemical Industry.

The potential use of bacteria and their derivatives as delivery systems for nanoparticles in the treatment of cancer

Cancer is a leading cause of mortality and morbidity worldwide. Nanomaterials, unique optical, magnetic, and electrical properties at the nanoscale (1-100 nm), have been engineered to improve drug capacity, bioavailability, and specificity in cancer treatment. These advancements address toxicity and lack of selectivity in conventional therapies, enabling precise targeting of cancer cells, the tumour microenvironment, and the immune system. Among emerging approaches, bacterial treatment shows promise due to its natural ability to target cancer and its diverse therapeutic mechanisms, which nanotechnology can further enhance. Bacteria-based drug delivery systems leverage bacteria's adaptability and survival strategies within the human body. Bacterial derivatives, such as bacterial ghosts (BGs), bacterial extracellular vesicles (BEVs), and dietary toxins, are recognised as effective biological nanomaterials capable of carrying nanoparticles (NPs). These systems have attracted increasing attention for their potential in targeted NP delivery for cancer treatment. This study explores the use of various bacteria and their byproducts as NP delivery vehicles, highlighting their potential in treating different types of cancer. By combining the strengths of nanotechnology and bacterial therapy, these innovative approaches aim to revolutionise cancer treatment with improved precision and efficacy.

Probiotic Lactobacillus-Derived Extracellular Vesicles: Insights Into Disease Prevention and Management

Bacterial extracellular vesicles (BEVs) have emerged as versatile and promising tools for therapeutic interventions across a spectrum of medical applications. Among these, Lactobacillus-derived extracellular vesicles (LDEVs) have garnered significant attention due to their diverse physiological functions and applications in health advancement. These LDEVs modulate host cell signaling pathways through the delivery of bioactive molecules, including nucleic acids and proteins. The immunomodulatory properties of LDEVs are important, as they have been shown to regulate the balance between pro-inflammatory and anti-inflammatory responses in various diseases. These LDEVs play a crucial role in maintaining gut homeostasis by modulating the composition and function of the gut microbiota, which has implications for health conditions, including inflammatory bowel diseases, metabolic disorders, and neurological disorders. Furthermore, LDEVs hold potential to deliver therapeutic payloads to specific tissues or organs. Engineered LDEVs can be loaded with therapeutic agents such as antimicrobial peptides or nucleic acid-based therapies to treat various diseases. By leveraging the unique properties of LDEVs, researchers can develop innovative strategies for disease prevention, treatment, and overall well-being. Thus, this review aims to provide a comprehensive overview of the therapeutic benefits of LDEVs and their implications for promoting overall well-being.

Membrane Vesicles from Lactobacillus Acidophilus Reduce Intestinal Inflammation and Increase 5-HT in the Substantia Nigra of Rats with Parkinson's Disease

BACKGROUND

This study aimed to investigate the role of membrane vesicles (MVs) from the probiotic Lactobacillus acidophilus in reducing intestinal inflammation and increasing 5-hydroxytryptamine (5-HT) and tyrosine hydroxylase (TH) in the substantia nigra in the 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease (PD).

METHODS

Twenty healthy male Wistar rats were randomly assigned to four groups (n = 5 per group), including a) control, b) 6-OHDA, c) 6-OHDA+MV, and d) sham groups. PD was induced by bilateral injection of 6-OHDA. Rats in the 6-OHDA+MV group received MV equivalent to 1 × 107 colony-forming units (CFU)/mL 3 d/wk by oral gavage for 4 wk. At the end of 4 wk, all rats were sacrificed; the brain and small intestine were removed for cellular and molecular analysis.

RESULTS

The induction of PD by 6-OHDA induced a remarkable decrease in beam-walking (p <0.0001). In addition, the expression of protein and genes (receptor) of 5-HT (r-5-HT1A) decreased, and that of protein and gene (receptor; GABBR1) of GABA increased in the PD group (p <0.05 compared with the healthy control group), while MV gavage of 6-OHDA-injected rats controlled these factors in the substantia nigra. In the intestinal tissue, the expression of TLR-4 and α-synuclein gene was significantly increased in the 6-OHDA group compared to the control group (p <0.0001).

CONCLUSION

MVs might act as potential beneficial tools to reduce intestinal inflammation, control neurological damage associated with PD, and increase 5-HT neurotransmitters. It seems that MVs from L. acidophilus may have therapeutic potential in Parkinson's neurological disorder by controlling the gut-brain axis.

Reducing severity of inflammatory bowel disease through colonization of Lactiplantibacillus plantarum and its extracellular vesicles release

Inflammatory bowel disease (IBD) is characterized by compromised intestinal barrier function and a lack of effective treatments. Probiotics have shown promise in managing IBD due to their ability to modulate the gut microbiota, enhance intestinal barrier function, and exert anti-inflammatory effects. However, the specific mechanisms through which probiotics exert these therapeutic effects in IBD treatment remain poorly understood. Our research revealed a significant reduction of Lactiplantibacillus plantarum (L. plantarum) in the gut microbiota of IBD patients. L. plantarum is a well-known probiotic strain in the list of edible probiotics, recognized for its beneficial effects on gut health, including its ability to strengthen the intestinal barrier and reduce inflammation. We demonstrated that supplementation with L. plantarum could alleviate IBD symptoms in mice, primarily by inhibiting apoptosis in intestinal epithelial cells through L. plantarum's bacterial extracellular vesicles (L. plant-EVs). This protective effect is dependent on the efficient uptake of L. plant-EVs by intestinal cells. Intriguingly, watermelon enhances L. plantarum colonization and L. plant-EVs release, further promoting intestinal barrier repair. Our findings contribute to the understanding of L. plant-EVs in the probiotic-based therapeutic approach for IBD, as they are promising candidates for nanoparticle-based therapeutic methods that are enhanced by natural diets such as watermelon. This study thereby offers a potential breakthrough in the management and treatment of IBD.

Extracellular Vesicles From Lactobacillus fermentum Enhance Intestinal Barrier Integrity and Restore Gut Microbial Homeostasis in Experimental Murine Colitis

BACKGROUND

Lactobacillus fermentum has been shown to improve intestinal health and treat colitis; however, its precise efficacy and mechanisms in inflammatory bowel disease remain unclear.

OBJECTIVES

This study aimed to evaluate whether L fermentum and its metabolites, extracellular vesicles, and other components could modulate intestinal barrier function and gut microbiota to alleviate dextran sulfate sodium (DSS)-induced colitis in mice.

METHODS

Forty-eight mice were randomly assigned to 6 groups: control, DSS, L fermentum+DSS group (LF+DSS), heat-inactivated L fermentum+DSS group (LHF+DSS), L fermentum supernatant solution+DSS group (LSF+DSS), and L fermentum extracellular vesicles+DSS group (LEV+DSS). After a 1-wk acclimation, mice were gavaged daily for 3 wk. Fresh cultures, including live (LF+DSS), heat-inactivated (LHF+DSS), supernatant (LSF+DSS), and extracellular vesicles (LEV+DSS), were prepared daily. During the final 7 d, the control group received normal water, and the other groups received 3% DSS. Data were collected daily, followed by sample collection from the mice.

RESULTS

In this study, significant reductions (P < 0.05) in body weight changes, disease activity index, intestinal damage, and histology scores were observed in the treatment groups, especially LEV+DSS and LF+DSS. Additionally, compared with the DSS group, colonic mucus secretion, as well as claudin-1 and occludin expression, increased significantly (P < 0.05) in the LEV+DSS and LF+DSS groups, whereas proinflammatory cytokines IL-1β and TNF-α decreased (P < 0.05) and IL-10 increased (P < 0.05) in the LEV+DSS group. L fermentum and its components significantly regulated gut microbiota α-diversity and β-diversity, affecting overall composition. Linear discriminant analysis effect size analysis revealed an enrichment of beneficial bacteria including Prevotellaceae_UCG-001, Romboutsia, and Ruminococcus species in the LF+DSS group and Akkermansia, Odoribacter, and Marvinbryantia species in the LEV+DSS group. Both L fermentum and its extracellular vesicles significantly downregulated the gene expression of TNF-α and IL-1β, whereas the expression of IL-10 was upregulated, thereby contributing to the alleviation of colitis symptoms.

CONCLUSIONS

This study reveals that L fermentum alleviates colitis through modulation of the gut microbiota and reinforcement of the intestinal mucosal barrier, with its extracellular vesicles potentially playing a key role in this regulatory process.

Psychobiotics and the gut-brain axis: advances in metabolite quantification and their implications for mental health

Psychobiotics are live microorganisms that, when administered in adequate amounts, confer mental health benefits to the host. Several clinical studies have demonstrated significant mental health benefits from psychobiotic administration, making them an emerging topic in food science. Certain strains of Lactobacillus, Bifidobacterium, Streptococcus, Escherichia, and Enterococcus species are known for their ability to modulate the gut-brain axis and provide mental health benefits. Proposed action mechanisms include the production of neuroactive compounds or their precursors, which may cross the blood-brain barrier, or transported by their extracellular vesicles. However, there is a lack of in vivo evidence directly confirming these mechanisms, although indirect evidence from recent studies suggest potential pathways for further investigation. To advance our understanding, it is crucial to study these mechanisms within the host, with accurate quantification of neuroactive compounds and/or their precursors being key in such studies. Current quantification methods, however, face challenges, such as low sensitivity for detecting trace metabolites and limited specificity due to interference from other compounds, impacting the reliability of measurements. This review discusses the emerging field of psychobiotics, their potential action mechanisms, neuroactive compound estimation techniques, and perspectives for improvement in quantifying neuroactive compounds and/or precursors within the host.

Multi-level analysis of gut microbiome extracellular vesicles-host interaction reveals a connection to gut-brain axis signaling

Microbiota-released extracellular vesicles (MEVs) have emerged as a key player in intercellular signaling. However, their involvement in the gut-brain axis has been poorly investigated. We hypothesize that MEVs cross host cellular barriers and deliver their cargoes of bioactive compounds to the brain. In this study, we aimed to investigate the cargo capacity of MEVs for bioactive metabolites and their interactions with the host cellular barriers. First, we conducted a multi-omics profiling of MEVs' contents from ex vivo and stool samples. Metabolomics analysis identified various neuro-related compounds encapsulated within MEVs, such as arachidonyl-dopamine, gabapentin, glutamate, and N-acylethanolamines. Metaproteomics unveiled an enrichment of enzymes involved in neuronal metabolism, primarily in the glutamine/glutamate/gamma-aminobutyric acid (GABA) pathway. These neuro-related proteins and metabolites were correlated with Bacteroides spp. We isolated 18 Bacteroides strains and assessed their GABA production capacity in extracellular vesicles (EVs) and culture supernatant. A GABA-producing Bacteroides finegoldii, released EVs with a high GABA content (4 µM) compared to Phocaeicola massiliensis. Upon testing the capacity of MEVs to cross host barriers, MEVs exhibited a dose-dependent paracellular transport and were endocytosed by Caco-2 and hCMEC/D3 cells. Exposure of Caco-2 cells to MEVs did not alter expression of genes related to intestinal barrier integrity, while affected immune pathways and cell apoptosis process as revealed by RNA-seq analyses. In vivo, MEVs biodistributed across mice organs, including the brain, liver, stomach, and spleen. Our results highlight the ability of MEVs to cross the intestinal and blood-brain barriers to deliver their cargoes to distant organs, with potential implication for the gut-brain axis.

IMPORTANCE

Microbiota-released extracellular vesicles (MEVs) have emerged as a key player in intercellular signaling. In this study, a multi-level analysis revealed presence of a diverse array of biologically active molecules encapsulated within MEVs, including neuroactive metabolites, such as arachidonyl-dopamine, gabapentin, glutamate, and N-acylethanolamines, and gamma-aminobutyric acid (GABA). Metaproteomics also unveiled an enrichment of neural-related proteins, mainly the glutamine/glutamate/GABA pathway. MEVs were able to cross epithelial and blood-brain barriers in vitro. RNA-seq analyses showed that MEVs stimulate several immune pathways while suppressing cell apoptosis process. Furthermore, MEVs were able to traverse the intestinal barriers and reach distal organs, including the brain, thereby potentially influencing brain functionality and contributing to mental and behavior.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

Equine endometrial bacteria inhibition by metabolite and extracellular vesicles of Lactobacillus acidophilus and lactiplantibacillus plantarum

Endometritis is one of the main reproductive disorders in mares and due to the increasing prevalence of antibiotic resistance, the use of probiotics in the prevention and treatment of endometritis in mares has gained interest, given their potential to restore and maintain a healthy uterine microbiota. Therefore, the aim of this study was to evaluate the antimicrobial properties of total metabolites of Lactobacillus acidophilus (LA) and Lactiplantibacillus plantarum (LP) against common equine endometrial pathogenic bacteria in vitro (Acinetobacter baumannii, Escherichia coli (1), Escherichia coli (2), Escherichia coli (3), Escherichia coli (4), Enterobacter cloacae, Streptococcus equi, Staphylococcus warneri, Actinobacillus equi and Klebesiella pneumoniae), as well as to assess their low molecular weight metabolites (loM) and extracellular vesicle (EVs) inhibition capacity over a multidrug-resistant E. coli isolated from mares with clinical endometritis. The total metabolites of LA showed better inhibition on A. baumannii, E. coli (1) and E. cloacae, while those of LP inhibited E. coli (4), S. equi and A. equi. Besides total metabolites, loM of LA and LP can inhibit E. coli. LA EVs were more effective in preventing E. coli (2) compared to LA loM, while LP EVs presented inhibition but below 90%. The use of LA and LP in the mare's uterus may be an interesting approach to controlling endometritis. In addition to metabolites, EVs can contribute to the inhibition of multidrug-resistant E. coli.

Extracellular vesicles from L. paracasei improve neuroinflammation, GABA neurotransmission and motor incoordination in hyperammonemic rats

Patients with liver cirrhosis may show minimal hepatic encephalopathy (MHE) with motor incoordination and cognitive impairment that reduce life quality and span. Motor incoordination is due to neuroinflammation and enhanced GABAergic neurotransmission in cerebellum. Recent reports support that probiotics, including L. casei, may improve cognitive function in different pathologies and MHE in cirrhotic patients. Extracellular vesicles (EV) are small cell-derived membrane vesicles that carry bioactive molecules released from cells, including bacteria. We hypothesized that EV from Lacticaseibacillus paracasei (LC-EV) could improve neuroinflammation, GABAergic neurotransmission and motor function in MHE. We show that LC-EV treatment reverses glial activation and neuroinflammation in cerebellum and restore motor coordination in hyperammonemic rats. Moreover, ex vivo treatment of cerebellar slices from hyperammonemic rats with LC-EV also reverses glial activation and neuroinflammation, and the enhancement of the TNFR1-S1PR2-BDNF-TrkB and TNFR1-TrkB-pAKT-NFκB-glutaminase-GAT3 pathways and of GABAergic neurotransmission. The results reported support that LC-EV may be used as a therapeutic tool to improve motor incoordination in patients with MHE.

Dietary Lactobacillus johnsonii-derived extracellular vesicles ameliorate acute colitis by regulating gut microbiota and maintaining intestinal barrier homeostasis

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease with intricate pathogenesis, and clinical treatment is still not ideal. The imbalance of gut microbiota is associated with IBD progression. Various probiotics have been used as functional foods for the prevention and treatment of IBD, but the specific mechanism is still not fully understood. Lactobacillus johnsonii (L. johnsonii) is a potential anti-inflammatory bacterium, and compared to other probiotic Lactobacillus species, its colonization in the gut of colitis patients is significantly reduced. In this study, we first found that dietary L. johnsonii exerts strong anti-inflammatory and antioxidant effects in colitis mice, and this beneficial effect is directly related to its derived extracellular vesicles (LJ-EVs). Further experimental results indicate that LJ-EVs effectively prevented colitis symptoms and modulated gut microbiota and metabolic pathways. Meanwhile, we have studied for the first time the protective effect of LJ-EVs on the intestinal barrier from the perspective of reducing oxidative stress. We found that LJ-EVs can be directly taken up by intestinal epithelial cells and activate the Nrf2/HO-1 antioxidant signaling pathway, reducing endotoxin damage to cells and maintaining intestinal barrier homeostasis, which cascades to alleviate intestinal inflammation response. This study reveals the mechanism of L. johnsonii in treating colitis and provides a new approach for the development of oral LJ-EVs for the treatment of colitis.

Probiotic bacteria-released extracellular vesicles enhance macrophage phagocytosis in polymicrobial sepsis by activating the FPR1/2 pathway

BACKGROUND

Sepsis-induced organ failure and high mortality are largely ascribed to the failure of bacterial clearance from the infected tissues. Recently, probiotic bacteria-released extracellular vesicles (BEVs) have been implicated as critical mediators of intercellular communication which are widely involved in the regulation of the inflammatory response. However, their functional role in macrophage phagocytosis during sepsis has never been explored.

METHODS

BEVs were collected from three different strains of probiotics including Lactiplantibacillus plantarum WCFS1 (LP WCFS1), Lactobacillus rhamnosus Gorbach-Goldin (LGG), and Escherichia coli Nissle 1917 (EcN), or from LGG cultured under three pH conditions (pH5-acid, pH6.5-standard, pH8-akaline) through differential centrifugation, filtration, and ultracentrifugation of their culture supernatants. In vitro phagocytosis was measured in Raw264.7 cells and bone marrow-derived macrophages using pHrodo red E. coli BioParticles. The in vivo therapeutic effects of BEVs were tested using a feces-injection-in-peritoneum (FIP) model of polymicrobial sepsis.

RESULTS

LGG-derived EVs (BEVLGG) were the best among these three probiotics BEVs in stimulating macrophages to take up bacteria. Furthermore, BEVLGG collected from pH8 culture condition (BEVpH8) exhibited the strongest capacity of phagocytosis, compared with BEVpH5 and BEVpH6.5. Treatment of septic mice with BEVpH8 significantly prolonged animal survival; increased bacterial clearance from the blood, peritoneal lavage fluid, and multiple organs; and decreased serum levels of pro-inflammatory cytokines/chemokines, as well as reduced multiple organ injuries, in comparison with control-treated septic mice. Mechanistically, RNA-seq and bioinformatic analysis identified that the FPR1/2 signaling was remarkably activated, along with its downstream pathways (PI3K-Akt-MARCO and NADPH-ROS) in BEVpH8-treated macrophages, compared with control cells. Accordingly, pre-addition of Boc2, a specific antagonist of FPR1/FPR2, to macrophages significantly attenuated BEVpH8-mediated phagocytosis, compared to controls.

CONCLUSIONS

This study demonstrates that LGG-derived BEVs may have therapeutic effects against sepsis-induced organ injury and mortality through enhancing FPR1/2-mediated macrophage phagocytosis.

Extracellular vesicles of Lactiplantibacillus plantarum PCM 2675 and Lacticaseibacillus rhamnosus PCM 489: an introductory characteristic

Aim: Extracellular vesicles (EVs) are involved in intercellular and interkingdom communication in the complex communities that constitute the niche-specific microbiome of the colonized host. Therefore, studying the structure and content of EVs produced by resident bacteria is crucial to understanding their functionality and impact on the host and other microorganisms. Methods: Bacterial EVs were isolated by differential centrifugation, their size and concentration were measured by transmission electron microscopy and nanoparticle tracking analysis, and the cargo proteins were identified by liquid chromatography coupled to tandem mass spectrometry. The cytotoxicity of bacterial EVs was tested using the human epithelial cell line A549 and an in vivo model of Galleria mellonella larvae. Results: The isolation and preliminary characteristics of EVs from two strains of lactic acid bacteria - Lactiplantibacillus plantarum PCM 2675 and Lacticaseibacillus rhamnosus PCM 489 - were presented, confirming the production of vesicular structures with sizes in the range of 50-170 nm for L. plantarum and 80-250 nm for L. rhamnosus. In addition, various proteins were identified within EVs cargo, with distinct locations of origin, including membrane, cytoplasmic and extracellular proteins, and with diverse functions, including enzymes with confirmed proteolytic activity. Furthermore, bacterial EVs did not show statistically significant cytotoxicity to the host under the tested conditions. Conclusions: A better understanding of the composition and functionality of bacterial EVs may contribute to their future effective use in supporting human health.

Deciphering the role of host-gut microbiota crosstalk via diverse sources of extracellular vesicles in colorectal cancer

Colorectal cancer is the most common type of cancer in the digestive system and poses a major threat to human health. The gut microbiota has been found to be a key factor influencing the development of colorectal cancer. Extracellular vesicles are important mediators of intercellular communication. Not only do they regulate life activities within the same individual, but they have also been found in recent years to be important mediators of communication between different species, such as the gut microbiota and the host. Their preventive, diagnostic, and therapeutic value in colorectal cancer is being explored. The aim of this review is to provide insights into the complex interactions between host and gut microbiota, particularly those mediated through extracellular vesicles, and how these interactions affect colorectal cancer development. In addition, the potential of extracellular vesicles from various body fluids as biomarkers was evaluated. Finally, we discuss the potential, challenges, and future research directions of extracellular vesicles in their application to colorectal cancer. Overall, extracellular vesicles have great potential for application in medical processes related to colorectal cancer, but their isolation and characterization techniques, intercellular communication mechanisms, and the effectiveness of their clinical application require further research and exploration.

Insights into the unique roles of extracellular vesicles for gut health modulation: Mechanisms, challenges, and perspectives

Extracellular vesicles (EVs), which play significant regulatory roles in maintaining homeostasis and influencing immune responses, significantly impact gut microbiota composition and function, affecting overall gut health. Despite considerable progress, there are still knowledge gaps regarding the mechanisms by which EVs, including plant-derived EVs (PDEVs), animal-derived EVs (ADEVs), and microbiota-derived EVs (MDEVs), modulate gut health. This review delves into the roles and mechanisms of EVs from diverse sources in regulating gut health, focusing on their contributions to maintaining epithelial barrier integrity, facilitating tissue healing, eliciting immune responses, controlling pathogens, and shaping microbiota. We emphasize open challenges and future perspectives for harnessing EVs in the modulation of gut health to gain a deeper understanding of their roles and impact. Importantly, a comprehensive research framework is presented to steer future investigations into the roles and implications of EVs on gut health, facilitating a more profound comprehension of this emerging field.

Extracellular Vesicles of the Probiotic Escherichia coli Nissle 1917 Reduce PepT1 Levels in IL-1β-Treated Caco-2 Cells via Upregulation of miR-193a-3p

PepT1, a proton-coupled oligopeptide transporter, is crucial for intestinal homeostasis. It is mainly expressed in small intestine enterocytes, facilitating the absorption of di/tri-peptides from dietary proteins. In the colon, PepT1 expression is minimal to prevent excessive responses to proinflammatory peptides from the gut microbiota. However, increased colonic PepT1 is linked to chronic inflammatory diseases and colitis-associated cancer. Despite promising results from animal studies on the benefits of extracellular vesicles (EVs) from beneficial gut commensals in treating IBD, applying probiotic EVs as a postbiotic strategy in humans requires a thorough understanding of their mechanisms. Here, we investigate the potential of EVs of the probiotic Nissle 1917 (EcN) and the commensal EcoR12 in preventing altered PepT1 expression under inflammatory conditions, using an interleukin (IL)-1-induced inflammation model in Caco-2 cells. The effects are evaluated by analyzing the expression of PepT1 (mRNA and protein) and miR-193a-3p and miR-92b, which regulate, respectively, PepT1 mRNA translation and degradation. The influence of microbiota EVs on PepT1 expression is also analyzed in the presence of bacterial peptides that are natural substrates of colonic PepT1 to clarify how the regulatory mechanisms function under both physiological and pathological conditions. The main finding is that EcN EVs significantly decreases PepT1 protein via upregulation of miR-193a-3p. Importantly, this regulatory effect is strain-specific and only activates in cells exposed to IL-1β, suggesting that EcN EVs does not control PepT1 expression under basal conditions but can play a pivotal role in response to inflammation as a stressor. By this mechanism, EcN EVs may reduce inflammation in response to microbiota in chronic intestinal disorders by limiting the uptake of bacterial proinflammatory peptides.

Bifidobacterium longum subsp. longum BG-L47 boosts growth and activity of Limosilactobacillus reuteri DSM 17938 and its extracellular membrane vesicles

The aim of this study was to identify a Bifidobacterium strain that improves the performance of Limosilactobacillus reuteri DSM 17938. Initial tests showed that Bifidobacterium longum subsp. longum strains boosted the growth of DSM 17938 during in vivo-like conditions. Further characterization revealed that one of the strains, BG-L47, had better bile and acid tolerance compared to BG-L48, as well as mucus adhesion compared to both BG-L48 and the control strain BB536. BG-L47 also had the capacity to metabolize a broad range of carbohydrates and sugar alcohols. Mapping of glycoside hydrolase (GH) genes of BG-L47 and BB536 revealed many GHs associated with plant-fiber utilization. However, BG-L47 had a broader phenotypic fiber utilization capacity. In addition, B. longum subsp. longum cells boosted the bioactivity of extracellular membrane vesicles (MV) produced by L. reuteri DSM 17938 during co-cultivation. Secreted 5'-nucleotidase (5'NT), an enzyme that converts AMP into the signal molecule adenosine, was increased in MV boosted by BG-L47. The MV exerted an improved antagonistic effect on the pain receptor transient receptor potential vanilloid 1 (TRPV1) and increased the expression of the immune development markers IL-6 and IL-1ß in a peripheral blood mononuclear cell (PBMC) model. Finally, the safety of BG-L47 was evaluated both by genome safety assessment and in a human safety study. Microbiota analysis showed that the treatment did not induce significant changes in the composition. In conclusion, B. longum subsp. longum BG-L47 has favorable physiological properties, can boost the in vitro activity of L. reuteri DSM 17938, and is safe for consumption, making it a candidate for further evaluation in probiotic studies.

IMPORTANCE

By using probiotics that contain a combination of strains with synergistic properties, the likelihood of achieving beneficial interactions with the host can increase. In this study, we first performed a broad screening of Bifidobacterium longum subsp. longum strains in terms of synergistic potential and physiological properties. We identified a superior strain, BG-L47, with favorable characteristics and potential to boost the activity of the known probiotic strain Limosilactobacillus reuteri DSM 17938. Furthermore, we demonstrated that BG-L47 is safe for consumption in a human randomized clinical study and by performing a genome safety assessment. This work illustrates that bacteria-bacteria interactions differ at the strain level and further provides a strategy for finding and selecting companion strains of probiotics.

Bacterial extracellular vesicles: Vital contributors to physiology from bacteria to host

Bacterial extracellular vesicles (bEVs) represent spherical particles with diameters ranging from 20 to 400 nm filled with multiple parental bacteria-derived components, including proteins, nucleic acids, lipids, and other biomolecules. The production of bEVs facilitates bacteria interacting with their environment and exerting biological functions. It is increasingly evident that the bEVs play integral roles in both bacterial and host physiology, contributing to environmental adaptations to functioning as health promoters for their hosts. This review highlights the current state of knowledge on the composition, biogenesis, and diversity of bEVs and the mechanisms by which different bEVs elicit effects on bacterial physiology and host health. We posit that an in-depth exploration of the mechanistic aspects of bEVs activity is essential to elucidate their health-promoting effects on the host and may facilitate the translation of bEVs into applications as novel natural biological nanomaterials.

Dual roles of the conditional extracellular vesicles derived from Pseudomonas aeruginosa biofilms: Promoting and inhibiting bacterial biofilm growth

Antibiotic-resistant biofilm infections have emerged as public health concerns because of their enhanced tolerance to high-dose antibiotic treatments. The biofilm life cycle involves multiple developmental stages, which are tightly regulated by active cell-cell communication via specific extracellular signal messengers such as extracellular vesicles. This study was aimed at exploring the roles of extracellular vesicles secreted by Pseudomonas aeruginosa at different developmental stages in controlling biofilm growth. Our results show that extracellular vesicles secreted by P. aeruginosa biofilms during their exponential growth phase (G-EVs) enhance biofilm growth. In contrast, extracellular vesicles secreted by P. aeruginosa biofilms during their death/survival phase (D-EVs) can effectively inhibit/eliminate P. aeruginosa PAO1 biofilms up to 4.8-log10 CFU/cm2. The inhibition effectiveness of D-EVs against P. aeruginosa biofilms grown for 96 h improved further in the presence of 10-50 μM Fe3+ ions. Proteomic analysis suggests the inhibition involves an iron-dependent ferroptosis mechanism. This study is the first to report the functional role of bacterial extracellular vesicles in bacterial growth, which depends on the developmental stage of the parent bacteria. The finding of D-EV-activated ferroptosis-based bacterial death may have significant implications for preventing antibiotic resistance in biofilms.

Isolation and Characteristics of Extracellular Vesicles Produced by Probiotics: Yeast Saccharomyces boulardii CNCM I-745 and Bacterium Streptococcus salivarius K12

Numerous probiotic microorganisms have repeatedly been shown to produce nanometer-sized structures named extracellular vesicles (EVs). Recently, it has been suggested that similarly to whole microbial cells, EVs produced by probiotics may also demonstrate health benefits to the host, while their application does not involve the risk of infection caused by live microorganisms. In this work, we isolated EVs from two probiotic species originating from different taxonomic domains - yeast Saccharomyces boulardii CNCM I-745 and bacterium Streptococcus salivarius K12. The diameters of S. boulardii EVs were about 142 nm and for S. salivarius EVs about 123 nm. For S. boulardii EVs, 1641 proteins and for S. salivarius EVs, 466 proteins were identified with a liquid chromatography-coupled tandem mass spectrometry and then functionally classified. In both microbial species, metabolic proteins significantly contributed to the cargo of EVs comprising 25% and 26% of all identified vesicular proteins for fungi and bacteria, respectively. Moreover, enzymes associated with cell wall rearrangement, including enzymatically active glucanases, were also identified in EVs. Furthermore, probiotic EVs were shown to influence host cells and stimulate the production of IL-1β and IL-8 by the human monocytic cell line THP-1, and, at the same time, did not cause any remarkable reduction in the survival rate of Galleria mellonella larvae in this invertebrate model commonly used to evaluate microbial EV toxicity. These observations suggest that the EVs produced by the investigated probiotic microorganisms may be promising structures for future use in pro-health applications.

A new frontier in precision medicine: Exploring the role of extracellular vesicles in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory airway disease characterized by progressive respiratory difficulties. It has a high incidence and disability rate worldwide. However, currently there is still a lack of highly effective treatment methods for COPD, only symptom relief is possible. Therefore, there is an urgent need to explore new treatment options. Almost all cells can secrete extracellular vesicles (EVs), which participate in many physiological activities by transporting cargoes and are associated with the pathogenesis of various diseases. Recently, many scholars have extensively studied the relationship between COPD and EVs, which has strongly demonstrated the significant impact of EVs from different sources on the occurrence and development of COPD. Therefore, EVs are a good starting point and new opportunity for the diagnosis and treatment of COPD. In this review, we mainly describe the current mechanisms of EVs in the pathogenesis of COPD, also the relationship between diagnosis, prognosis, and treatment. At the same time, we also introduce some new methods for COPD therapy based on EVs. It is hoped that this article can provide new ideas for future research and contribute to the development of precision medicine.

The inhibitory effects of live and UV-killed Akkermansia muciniphila and its derivatives on cytotoxicity and inflammatory response induced by Clostridioides difficile RT001 in vitro

Clostridioides difficile infection (CDI) is the leading cause of healthcare-acquired infections worldwide. Probiotics are widely recommended to prevent CDI and its recurrences. Akkermansia muciniphila, as a therapeutic symbiont colonizing the intestinal mucosal layer, is considered to be a promising next-generation probiotic. In this work, we assessed the inhibitory effects of A. muciniphila MucT and its derivatives on cytotoxicity and inflammatory response induced by C. difficile RT001 in Caco-2 cells. The results obtained from SEM revealed that the morphology of UV-killed A. muciniphila remained unchanged after UV inactivation. TEM analysis showed that A. muciniphila-isolated extracellular vesicles (EVs) were spherical and ranged from 50 to 200 nm in size. Toxigenic supernatant (Tox-S) of C. difficile RT001 (500 μg/ml) significantly (P <0.01) reduced the cell viability of Caco-2 cells. Caco-2 cells treated with live (MOI 10), UV-killed (MOI 10), cell-free supernatant (CFS, 106 cfu/ml), and EVs (20 μg/ml) of A. muciniphila exhibited over 90% viability in comparison to untreated control. The neutralized CFS preparation using A. muciniphila and its derivatives could notably reduce the expression level of inflammatory markers. Additionally, A. muciniphila and its derivatives modulated the production of IL-1β, TNF-α, and IL-10 in Tox-S stimulated Caco-2 cells. We demonstrated that A. muciniphila and its derivatives can modulate changes in the gut barrier-related genes and inflammatory response caused by C. difficile Tox-S in Caco-2 cells.

The activation impact of lactobacillus-derived extracellular vesicles on lipopolysaccharide-induced microglial cell

Perioperative neurocognitive dysfunction (PND) emerges as a common postoperative complication among elderly patients. Currently, the mechanism of PND remains unclear, but there exists a tendency to believe that inflammation plays a significant role in PND. Alterations in the abundance of intestinal microbiota can increase the permeability of the intestinal mucosal barrier and incite extraintestinal inflammatory responses. Metabolites from these microbiota can be absorbed by the intestinal mucosa into the bloodstream, exerting influence upon the central nervous system (CNS). Lactobacillus (Lac), serving as an intestinal probiotic bacterium, possesses the capacity to modulate emotional behavior and cognitive functions. Extracellular vesicles (EVs) are recognized as novel therapeutic carriers for targeted delivery to regulate physiology and pathogenesis. While the mechanism governing the primary function of Lac-EVs in the CNS remains uncertain. Therefore, we established an in vitro neuroinflammation model to induce PND and then treated the mice with Lac-EVs to observe the effect of these EVs on neuroinflammation, particularly on microglial (MG) polarization. Our research unveils that Lac-EVs reduced inflammation induced by LPS in microglia and the activation of related proteins, including the mRNA expression of M1 labeled protein (iNOS). Moreover, the mRNA expression of M2-labeled protein (Arg1) increased. In addition, flow cytometry revealed that the ratio of M1/M2 microglia also changed significantly. Therefore, Lac-EVs promoted the differentiation of M2 microglia by inducing the preferential expression of specific markers related to M2 macrophages and inflammation. In terms of inflammatory cytokine expression, Lac-EVs decreased the secretion of proinflammatory cytokines (IL-1β and IL-6) and increased IL-10 production after lipopolysaccharide (LPS) stimulation. Therefore, Lac-EVs induce the activation of M2 microglial cells without inducing cellular harm in vitro, and they demonstrate anti-inflammatory effects against lipopolysaccharide-induced neuroinflammation. This finding suggested that it is an effective anti-inflammatory strategy for alleviating inflammation-driven PNDs.

Extracellular vesicles from Lacticaseibacillus paracasei PC-H1 inhibit HIF-1α-mediated glycolysis of colon cancer

Aims: Extracellular vesicles from Lacticaseibacillus paracasei PC-H1 have antiproliferative activity of colon cells, but the effect on glycolytic metabolism of cancer cell remains enigmatic. The authors investigated how Lacticaseibacillus paracasei extracellular vesicles (LpEVs) inhibit the growth of colon cancer cells by affecting tumor metabolism. Materials & methods: HCT116 cells were treated with LpEVs and then differentially expressed genes were analyzed by transcriptome sequencing, the sequencing results were confirmed in vivo and in vitro. Results: LpEVs entered colon cancer cells and inhibited their growth. Transcriptome sequencing revealed differentially expressed genes were related to glycolysis. Lactate production, glucose uptake and lactate dehydrogenase activity were significantly reduced after treatment. LpEVs also reduced HIF-1α, GLUT1 and LDHA expression. Conclusion: LpEVs exert their antiproliferative activity of colon cancer cells by decreasing HIF-1α-mediated glycolysis.

Yeast strains isolated from fermented beverage produce extracellular vesicles with anti-inflammatory effects

Extracellular vesicles (EVs) are lipid-bilayered particles, containing various biomolecules, including nucleic acids, lipids, and proteins, released by cells from all the domains of life and performing multiple communication functions. Evidence suggests that the interaction between host immune cells and fungal EVs induces modulation of the immune system. Most of the studies on fungal EVs have been conducted in the context of fungal infections; therefore, there is a knowledge gap in what concerns the production of EVs by yeasts in other contexts rather than infection and that may affect human health. In this work, we characterized EVs obtained by Saccharomyces cerevisiae and Pichia fermentans strains isolated from a fermented milk product with probiotic properties. The immunomodulation abilities of EVs produced by these strains have been studied in vitro through immune assays after internalization from human monocyte-derived dendritic cells. Results showed a significant reduction in antigen presentation activity of dendritic cells treated with the fermented milk EVs. The small RNA fraction of EVs contained mainly yeast mRNA sequences, with a few molecular functions enriched in strains of two different species isolated from the fermented milk. Our results suggest that one of the mechanisms behind the anti-inflammatory properties of probiotic foods could be mediated by the interactions of human immune cells with yeast EVs.

Mesenchymal stem cells and their extracellular vesicles in urological cancers: Prostate, bladder, and kidney

Mesenchymal stem cells (MSCs) are recognized for their remarkable ability to differentiate into multiple cell types. They are also known to possess properties that can fight cancer, leading to attempts to modify MSCs for use in anticancer treatments. However, MSCs have also been found to participate in pathways that promote tumor growth. Many studies have been conducted to explore the potential of MSCs for clinical applications, but the results have been inconclusive, possibly due to the diverse nature of MSC populations. Furthermore, the conflicting roles of MSCs in inhibiting tumors and promoting tumor growth hinder their adaptation to anticancer therapies. Antitumorigenic and protumorigenic properties of MSCs in urological cancers such as bladder, prostate, and renal are not as well established, and data comparing them are still limited. MSCs hold significant promise as a vehicle for delivering anticancer agents and suicide genes to tumors. Presently, numerous studies have concentrated on the products derived from MSCs, such as extracellular vesicles (EVs), as a form of cell-free therapy. This work aimed to review and discuss the current knowledge of MSCs and their EVs in urological cancer therapy.

Immunological Regulation of Gut-Tropic Immune Cells by Extracellular Vesicles

The remarkable diversity of lymphocytes, essential components of the immune system, serves as an ingenious mechanism for maximizing the efficient utilization of limited host defense resources. While cell adhesion molecules, notably in gut-tropic T cells, play a central role in this mechanism, the counterbalancing molecular details have remained elusive. Conversely, we've uncovered the molecular pathways enabling extracellular vesicles secreted by lymphocytes to reach the gut's mucosal tissues, facilitating immunological regulation. This discovery sheds light on immune fine-tuning, offering insights into immune regulation mechanisms.

Postbiotics: Functional Food Materials and Therapeutic Agents for Cancer, Diabetes, and Inflammatory Diseases

Postbiotics are (i) "soluble factors secreted by live bacteria, or released after bacterial lysis, such as enzymes, peptides, teichoic acids, peptidoglycan-derived muropeptides, polysaccharides, cell-surface proteins and organic acids"; (ii) "non-viable metabolites produced by microorganisms that exert biological effects on the hosts"; and (iii) "compounds produced by microorganisms, released from food components or microbial constituents, including non-viable cells that, when administered in adequate amounts, promote health and wellbeing". A probiotic- and prebiotic-rich diet ensures an adequate supply of these vital nutrients. During the anaerobic fermentation of organic nutrients, such as prebiotics, postbiotics act as a benevolent bioactive molecule matrix. Postbiotics can be used as functional components in the food industry by offering a number of advantages, such as being added to foods that are harmful to probiotic survival. Postbiotic supplements have grown in popularity in the food, cosmetic, and healthcare industries because of their numerous health advantages. Their classification depends on various factors, including the type of microorganism, structural composition, and physiological functions. This review offers a succinct introduction to postbiotics while discussing their salient features and classification, production, purification, characterization, biological functions, and applications in the food industry. Furthermore, their therapeutic mechanisms as antibacterial, antiviral, antioxidant, anticancer, anti-diabetic, and anti-inflammatory agents are elucidated.

Advancement of Engineered Bacteria for Orally Delivered Therapeutics

The use of bacteria and their biotic components as therapeutics has shown great potential in the treatment of diseases. Orally delivered bacteria improve patient compliance compared with injection-administered bacteria and are considered the preferred mode. However, due to the harsh gastrointestinal environment, the viability and therapeutic efficacy of orally delivered bacteria are significantly reduced in vivo. In recent years, with the rapid development of synthetic biology and nanotechnology, bacteria and biotic components have been engineered to achieve directed genetic reprogramming for construction and precise spatiotemporal control in the gastrointestinal tract, which can improve viability and therapeutic efficiency. Herein, a state-of-the-art review on the current progress of engineered bacterial systems for oral delivery is provided. The different types of bacterial and biotic components for oral administration are first summarized. The engineering strategies of these bacteria and biotic components and their treatment of diseases are next systematically summarized. Finally, the current challenges and prospects of these bacterial therapeutics are highlighted that will contribute to the development of next-generation orally delivered bacteriotherapy.

Human gut homeostasis and regeneration: the role of the gut microbiota and its metabolites

The healthy human gut is a balanced ecosystem where host cells and representatives of the gut microbiota interact and communicate in a bidirectional manner at the gut epithelium. As a result of these interactions, many local and systemic processes necessary for host functionality, and ultimately health, take place. Impairment of the integrity of the gut epithelium diminishes its ability to act as an effective gut barrier, can contribute to conditions associated to inflammation processes and can have other negative consequences. Pathogens and pathobionts have been linked with damage of the integrity of the gut epithelium, but other components of the gut microbiota and some of their metabolites can contribute to its repair and regeneration. Here, we review what is known about the effect of bacterial metabolites on the gut epithelium and, more specifically, on the regulation of repair by intestinal stem cells and the regulation of the immune system in the gut. Additionally, we explore the potential therapeutic use of targeted modulation of the gut microbiota to maintain and improve gut homeostasis as a mean to improve health outcomes.

Immunostimulating Commensal Bacteria and Their Potential Use as Therapeutics

The gut microbiome is intimately intertwined with the host immune system, having effects on the systemic immune system. Dysbiosis of the gut microbiome has been linked not only to gastrointestinal disorders but also conditions of the skin, lungs, and brain. Commensal bacteria can affect the immune status of the host through a stimulation of the innate immune system, training of the adaptive immune system, and competitive exclusion of pathogens. Commensal bacteria improve immune response through the production of immunomodulating compounds such as microbe-associated molecular patterns (MAMPs), short-chain fatty acids (SCFAs), and secondary bile acids. The microbiome, especially when in dysbiosis, is plastic and can be manipulated through the introduction of beneficial bacteria or the adjustment of nutrients to stimulate the expansion of beneficial taxa. The complex nature of the gastrointestinal tract (GIT) ecosystem complicates the use of these methods, as similar treatments have various results in individuals with different residential microbiomes and differential health statuses. A more complete understanding of the interaction between commensal species, host genetics, and the host immune system is needed for effective microbiome interventions to be developed and implemented in a clinical setting.

Extracellular vesicles as a novel mediator of interkingdom communication

Extracellular vesicles (EVs) are nanosized lipid bilayer-delimited particles secreted from almost all types of cells including bacteria, mammals and plants, and are presumed to be mediators of intercellular communication. Bacterial extracellular vesicles (BEVs) are nanoparticles with diverse diameters, ranging from 20 to 400 nm. BEVs are composed of soluble microbial metabolites, including nucleic acid, proteins, lipoglycans, and short-chain fatty acids (SCFAs). In addition, EVs may contain quorum sensing peptides that are endowed with the ability to protect bacteria against bacteriophages, form and maintain bacterial communities, and modulate the host immune system. BEVs are potentially promising therapeutic modalities for use in vaccine development, cancer immunotherapy regimens, and drug delivery cargos. Plant-derived EVs (PEVs), such as EVs derived from herbal medicines, can be absorbed by the gut microbiota and influence the composition and homeostasis of gut microbiota. This review highlights the roles of BEVs and PEVs in bacterial and plant physiology and discusses crosstalk among gut bacteria, host metabolism and herbal medicine. In summary, EVs represent crucial communication messengers in the gut microbiota, with potential therapeutic value in the delivery of herbal medicines.

Carbohydrate polymer-based carriers for colon targeted delivery of probiotics

Probiotics (PRO) have been recognized for their significant role in promoting human health, particularly in relation to colon-related diseases. The effective delivery of PRO to the colon is a fascinating area of research. Among various delivery materials, carbohydrates have shown great potential as colon-targeted delivery (CTD) carriers for PRO. This review explores the connection between probiotics and colonic diseases, delving into their underlying mechanisms of action. Furthermore, it discusses current strategies for the targeted delivery of active substances to the colon. Unlike other reviews, this work specifically focuses on the utilization of carbohydrates, such as alginate, chitosan, pectin, and other carbohydrates, for probiotic colon-targeted delivery applications. Carbohydrates can undergo hydrolysis at the colonic site, allowing their oligosaccharides to function as prebiotics or as direct functional polysaccharides with beneficial effects. Furthermore, the development of multilayer self-assembled coatings using different carbohydrates enables the creation of enhanced delivery systems. Additionally, chemical modifications of carbohydrates, such as for adhesion and sensitivity, can be implemented to achieve more customized delivery of PRO.

Membrane vesicles from Lactobacillus johnsonii delay osteoarthritis progression via modulating macrophage glutamine synthetase/mTORC1 axis

AIMS

The manipulation of macrophage recruitment and their shift in the M1/M2 ratio is a promising approach to mitigate osteoarthritis (OA). Nevertheless, the current clinical medication available for OA is only palliative and may result in undesirable outcomes. Hence, it is urgent to explore alternative disease-modifying drug supplement that are both safer and more effective in OA treatment, like probiotic and probiotic-derived membrane vesicles.

METHODS

The synovial inflammation and cartilage damage in collagenase-induced OA (CIOA) mice were observed using haematoxylin and eosin, saffron O-solid green and immunohistochemical staining. Bipedal balance test and open field test were conducted to determine the effectiveness of L. johnsonii-derived membrane vesicles (LJ-MVs) in reducing joint pain of CIOA mice. Additionally, Transwell, western blot, and immunological testing were used to examine the effect of LJ-MVs on macrophage migration and reprogramming. Furthermore, a 4D label-free proteomic analysis of LJ-MVs and their parent bacterium was performed, and the glutamine synthetase (GS)/mTORC1 axis in macrophage was verified by western blot.

RESULTS

L. johnsonii and its membrane vesicles, LJ-MVs, exhibit a novel ability to mitigate inflammation, cartilage damage, and pain associated with OA. This is achieved by their ability to impede macrophage migration, M1-like polarization, and inflammatory mediators secretion, while simultaneously promoting the M2/M1 ratio in synovial macrophages. The mechanism underlying this effect involves the modulation of macrophage GS/mTORC1 pathway, at least partially.

SIGNIFICANCE

Owing to their probiotic derivation, LJ-MVs will be a more dependable and potent disease-modifying drugs for the prevention and therapy of OA in the long run.

Characterization of the Inflammatory Response Evoked by Bacterial Membrane Vesicles in Intestinal Cells Reveals an RIPK2-Dependent Activation by Enterotoxigenic Escherichia coli Vesicles

Although the immunomodulatory potency of bacterial membrane vesicles (MVs) is widely acknowledged, their interactions with host cells and the underlying signaling pathways have not been well studied. Herein, we provide a comparative analysis of the proinflammatory cytokine profile secreted by human intestinal epithelial cells exposed to MVs derived from 32 gut bacteria. In general, outer membrane vesicles (OMVs) from Gram-negative bacteria induced a stronger proinflammatory response than MVs from Gram-positive bacteria. However, the quality and quantity of cytokine induction varied between MVs from different species, highlighting their unique immunomodulatory properties. OMVs from enterotoxigenic Escherichia coli (ETEC) were among those showing the strongest proinflammatory potency. In depth analyses revealed that the immunomodulatory activity of ETEC OMVs relies on a so far unprecedented two-step mechanism, including their internalization into host cells followed by intracellular recognition. First, OMVs are efficiently taken up by intestinal epithelial cells, which mainly depends on caveolin-mediated endocytosis as well as the presence of the outer membrane porins OmpA and OmpF on the MVs. Second, lipopolysaccharide (LPS) delivered by OMVs is intracellularly recognized by novel caspase- and RIPK2-dependent pathways. This recognition likely occurs via detection of the lipid A moiety as ETEC OMVs with underacylated LPS exhibited reduced proinflammatory potency but similar uptake dynamics compared to OMVs derived from wild-type (WT) ETEC. Intracellular recognition of ETEC OMVs in intestinal epithelial cells is pivotal for the proinflammatory response as inhibition of OMV uptake also abolished cytokine induction. The study signifies the importance of OMV internalization by host cells to exercise their immunomodulatory activities. IMPORTANCE The release of membrane vesicles from the bacterial cell surface is highly conserved among most bacterial species, including outer membrane vesicles (OMVs) from Gram-negative bacteria as well as vesicles liberated from the cytoplasmic membrane of Gram-positive bacteria. It is becoming increasingly evident that these multifactorial spheres, carrying membranous, periplasmic, and even cytosolic content, contribute to intra- and interspecies communication. In particular, gut microbiota and the host engage in a myriad of immunogenic and metabolic interactions. This study highlights the individual immunomodulatory activities of bacterial membrane vesicles from different enteric species and provides new mechanistic insights into the recognition of ETEC OMVs by human intestinal epithelial cells.

Modulation of bone remodeling by the gut microbiota: a new therapy for osteoporosis

The gut microbiota (GM) plays a crucial role in maintaining the overall health and well-being of the host. Recent studies have demonstrated that the GM may significantly influence bone metabolism and degenerative skeletal diseases, such as osteoporosis (OP). Interventions targeting GM modification, including probiotics or antibiotics, have been found to affect bone remodeling. This review provides a comprehensive summary of recent research on the role of GM in regulating bone remodeling and seeks to elucidate the regulatory mechanism from various perspectives, such as the interaction with the immune system, interplay with estrogen or parathyroid hormone (PTH), the impact of GM metabolites, and the effect of extracellular vesicles (EVs). Moreover, this review explores the potential of probiotics as a therapeutic approach for OP. The insights presented may contribute to the development of innovative GM-targeted therapies for OP.

Different culture media and purification methods unveil the core proteome of Propionibacterium freudenreichii-derived extracellular vesicles

Bacterial extracellular vesicles (EVs) are natural lipidic nanoparticles implicated in intercellular communication. Although EV research focused mainly on pathogens, the interest in probiotic-derived EVs is now rising. One example is Propionibacterium freudenreichii, which produces EVs with anti-inflammatory effects on human epithelial cells. Our previous study with P. freudenreichii showed that EVs purified by size exclusion chromatography (SEC) displayed variations in protein content according to bacterial growth conditions. Considering these content variations, we hypothesized that a comparative proteomic analysis of EVs recovered in different conditions would elucidate whether a representative vesicular proteome existed, possibly providing a robust proteome dataset for further analysis. Therefore, P. freudenreichii was grown in two culture media, and EVs were purified by sucrose density gradient ultracentrifugation (UC). Microscopic and size characterization confirmed EV purification, while shotgun proteomics unveiled that they carried a diverse set of proteins. A comparative analysis of the protein content of UC- and SEC-derived EVs, isolated from cultures either in UF (cow milk ultrafiltrate medium) or YEL (laboratory yeast extract lactate medium), showed that EVs from all these conditions shared 308 proteins. This EV core proteome was notably enriched in proteins related to immunomodulation. Moreover, it showed distinctive features, including highly interacting proteins, compositional biases for some specific amino acids, and other biochemical parameters. Overall, this work broadens the toolset for the purification of P. freudenreichii-derived EVs, identifies a representative vesicular proteome, and enumerates conserved features in vesicular proteins. These results hold the potential for providing candidate biomarkers of purification quality, and insights into the mechanisms of EV biogenesis and cargo sorting.

Engineering fucoxanthin-loaded probiotics' membrane vesicles for the dietary intervention of colitis

Extracellular vesicles (EVs) are very attractive as carriers of active components due to their good immunological and their ability to penetrate the physiological barrier that synthetic delivery carriers cannot penetrate. However, the low secretion capacity of EVs limited its widespread adoption, let alone the lower yield of EVs loaded with active components. Here, we report a large-scale engineering preparation strategy of synthetic probiotic membrane vesicles for encapsulating fucoxanthin (FX-MVs), an intervention for colitis. Compared with the EVs naturally secreted by probiotics, the engineering membrane vesicles showed a 150-fold yield and richer protein. Moreover, FX-MVs improved the gastrointestinal stability of fucoxanthin and inhibited H₂O₂-induced oxidative damage by scavenging free radicals effectively (p < 0.05). The in vivo results showed that FX-MVs could promote the polarization of macrophages to M2 type, prevent the injury and shortening of colon tissue (p < 0.05), and improve the colonic inflammatory response. Consistently, proinflammatory cytokines were effectively suppressed after FX-MVs treatment (p < 0.05). Unexpectedly, such engineering FX-MVs could also reshape the gut microbiota communities and improve the abundance of short-chain fatty acids in the colon. This study lays a foundation for developing dietary interventions using natural foods to treat intestinal-related diseases.

Novel Horizons in Postbiotics: Lactobacillaceae Extracellular Vesicles and Their Applications in Health and Disease

Lactobacillus probiotics contained in dietary supplements or functional foods are well-known for their beneficial properties exerted on host health and diverse pathological situations. Their capacity to improve inflammatory bowel disease (IBD) and regulate the immune system is especially remarkable. Although bacteria-host interactions have been thought to occur directly, the key role that extracellular vesicles (EVs) derived from probiotics play on this point is being unveiled. EVs are lipid bilayer-enclosed particles that carry a wide range of cargo compounds and act in different signalling pathways. Notably, these EVs have been recently proposed as a safe alternative to the utilisation of live bacteria since they can avoid the possible risks that probiotics may entail in vulnerable cases such as immunocompromised patients. Therefore, this review aims to give an updated overview of the existing knowledge about EVs from different Lactobacillus strains, their mechanisms and effects in host health and different pathological conditions. All of the information collected suggests that EVs could be considered as potential tools for the development of future novel therapeutic approaches.

Bacterial extracellular vesicles and their novel therapeutic applications in health and cancer

Bacterial cells communicate with host cells and other bacteria through the release of membrane vesicles known as bacterial extracellular vesicles (BEV). BEV are established mediators of intracellular signaling, stress tolerance, horizontal gene transfer, immune stimulation and pathogenicity. Both Gram-positive and Gram-negative bacteria produce extracellular vesicles through different mechanisms based on cell structure. BEV contain and transfer different types of cargo such as nucleic acids, proteins and lipids, which are used to interact with and affect host cells such as cytotoxicity and immunomodulation. The role of these membranous microvesicles in host communication, intra- and inter-species cell interaction and signaling, and contribution to various diseases have been well demonstrated. Due to their structure, these vesicles can be easily engineered to be utilized for clinical application, as shown with its role in vaccine therapy, and could be used as a diagnostic and cancer drug delivery tool in the future. However, like other novel therapeutic approaches, further investigation and standardization is imperative for BEV to become a routine vector or a conventional treatment method.

Akkermansia muciniphila and Gut Immune System: A Good Friendship That Attenuates Inflammatory Bowel Disease, Obesity, and Diabetes

Akkermansia muciniphila is a Gram-negative anaerobic mucus-layer-degrading bacterium that colonizes the intestinal mucosa of humans and rodents. Metagenomic data have shown an inverse correlation between the abundance of A. muciniphila and diseases such as inflammatory bowel disease (IBD), obesity, and diabetes. Thus, in recent decades, the potential of this bacterium as an immunomodulatory probiotic for autoimmune and chronic inflammatory diseases has been explored in experimental models. Corroborating these human correlation data, it has been reported that A. muciniphila slows down the development and progression of diabetes, obesity, and IBD in mice. Consequently, clinical studies with obese and diabetic patients are being performed, and the preliminary results are very promising. Therefore, this mini review highlights the main findings regarding the beneficial roles of A. muciniphila and its action mechanisms in autoimmune and chronic inflammatory diseases.

Postbiotics as potential new therapeutic agents for metabolic disorders management

The prevalence of obesity, diabetes, non-alcoholic fatty liver disease, and related metabolic disorders has been steadily increasing in the past few decades. Apart from the establishment of caloric restrictions in combination with improved physical activity, there are no effective pharmacological treatments for most metabolic disorders. Many scientific-studies have described various beneficial effects of probiotics in regulating metabolism but others questioned their effectiveness and safety. Postbiotics are defined as preparation of inanimate microorganisms, and/or their components, which determine their safety of use and confers a health benefit to the host. Additionally, unlike probiotics postbiotics do not require stringent production/storage conditions. Recently, many lines of evidence demonstrated that postbiotics may be beneficial in metabolic disorders management via several potential effects including anti-inflammatory, antibacterial, immunomodulatory, anti-carcinogenic, antioxidant, antihypertensive, anti-proliferative, and hypocholesterolaemia properties that enhance both the immune system and intestinal barrier functions by acting directly on specific tissues of the intestinal epithelium, but also on various organs or tissues. In view of the many reports that demonstrated the high biological activity and safety of postbiotics, we summarized in the present review the current findings reporting the beneficial effects of various probiotics derivatives for the management of metabolic disorders and related alterations.

Engineered microbial systems for advanced drug delivery

The human body is a natural habitat for a multitude of microorganisms, with bacteria being the major constituent of the microbiota. These bacteria colonize discrete anatomical locations that provide suitable conditions for their survival. Many bacterial species, both symbiotic and pathogenic, interact with the host via biochemical signaling. Based on these attributes, commensal and attenuated pathogenic bacteria have been engineered to deliver therapeutic molecules to target specific diseases. Recent advances in synthetic biology have enabled us to perform complex genetic modifications in live bacteria and bacteria-derived particles, which simulate micron or submicron lipid-based vectors, for the targeted delivery of therapeutic agents. In this review, we highlight various examples of engineered bacteria or bacteria-derived particles that encapsulate, secrete, or surface-display therapeutic molecules for the treatment or prevention of various diseases. The review highlights recent studies on (i) the production of therapeutics by microbial cell factories, (ii) disease-triggered release of therapeutics by sense and respond systems, (iii) bacteria targeting tumor hypoxia, and (iv) bacteria-derived particles as chassis for drug delivery. In addition, we discuss the potential of such drug delivery systems to be translated into clinical therapies.

Effects of gut microbiota-derived extracellular vesicles on obesity and diabetes and their potential modulation through diet

Obesity and diabetes incidence rates are increasing dramatically, reaching pandemic proportions. Therefore, there is an urgent need to unravel the mechanisms underlying their pathophysiology. Of particular interest is the close interconnection between gut microbiota dysbiosis and obesity and diabetes progression. Hence, microbiota manipulation through diet has been postulated as a promising therapeutic target. In this regard, secretion of gut microbiota-derived extracellular vesicles is gaining special attention, standing out as key factors that could mediate gut microbiota-host communication. Extracellular vesicles (EVs) derived from gut microbiota and probiotic bacteria allow to encapsulate a wide range of bioactive molecules (such as/or including proteins and nucleic acids) that could travel short and long distances to modulate important biological functions with the overall impact on the host health. EV-derived from specific bacteria induce differential physiological responses. For example, a high-fat diet-induced increase of the proteobacterium Pseudomonas panacis-derived EV is closely associated with the progression of metabolic dysfunction in mice. In contrast, Akkermansia muciniphila EV are linked with the alleviation of high-fat diet-induced obesity and diabetes in mice. Here, we review the newest pieces of evidence concerning the potential role of gut microbiota and probiotic-derived EV on obesity and diabetes onset, progression, and management, through the modulation of inflammation, metabolism, and gut permeability. In addition, we discuss the role of certain dietary patterns on gut microbiota-derived EV profile and the clinical implication that dietary habits could have on metabolic diseases progression through the shaping of gut microbiota-derived EV.

A novel bioactive postbiotics: from microbiota-derived extracellular nanoparticles to health promoting

In recent years, the emerging concern regarding safety issues associated with live bacterial cells is enhancing the interest in using cell components and metabolites derived from microbiota. Therefore, the term "postbiotics" is increasingly found in food microbiology, food scientific and commercial products. Postbiotics is defined as non-viable microorganisms or their components that provide benefits to the host. Many in vivo and in vitro experiments have shown that beneficial microbiota-generated extracellular nanoparticles (NPs) confer unique health promoting functions to the intestinal local and systemic effects, which can be considered as a novel postbiotics. Meanwhile, the postbiotics-NPs is a protective complex, delivering bioactive components to reach distant tissues and organs at high concentrations. These properties demonstrate that postbiotics-NPs may contribute to the improvement of host health by regulating specific gut microbiota and physiological functions, while the exact mechanisms are not fully elucidated. This review highlights the current understanding of postbiotics-NPs functional properties and mechanisms of health benefits, especially focusing on the interactions in gut microbiota and host, functions in human health and potential applications in future functional food and biomedical fields.