Microbiota-derived extracellular vesicles in interkingdom communication in the gut

Opportunities and challenges of bacterial extracellular vesicles in regenerative medicine

Extracellular vesicles (EVs) are membrane-bound vesicles that are shed or secreted from the cell membrane and enveloped by a lipid bilayer. They possess stability, low immunogenicity, and non-cytotoxicity, exhibiting extensive prospects in regenerative medicine (RM). However, natural EVs pose challenges, such as insufficient targeting capabilities, potential biosafety concerns, and limited acquisition pathways. Although engineered EVs demonstrate excellent therapeutic efficacy, challenges such as low production yield and the complexity of engineering modifications constrain their further clinical applications. Bacteria have advantages such as rapid proliferation, diverse gene editing methods, mature cultivation techniques, and relatively easy preparation of bacterial EVs (BEVs), which can be used to effectively address the challenges currently encountered in the field of EVs. This review provides a description of the biogenesis and pathophysiological functions of BEVs, and strategies for optimizing BEVs preparation to attain efficiency and safety are discussed. An analysis of natural characteristics of BEVs is also conducted to explore how to leverage their advantages or mitigate their limitations, thereby overcoming constraints on the application of BEVs in RM. In summary, engineered BEVs possess characteristics such as high production yield, excellent stability, and high drug-delivering capabilities, laying the foundation for their application in RM.

Microbial DNA Profiles of Bacterial Extracellular Vesicles from 3D Salivary Polymicrobial Biofilms - A Pilot Study

With the advent of multi-layered and 3D scaffolds, the understanding of microbiome composition and pathogenic mechanisms within polymicrobial biofilms is continuously evolving. A fundamental component in mediating the microenvironment and bacterial-host communication within the biofilm are bilayered nanoparticles secreted by bacteria, known as bacterial extracellular vesicles (BEVs), which transport key biomolecules including proteins, nucleic acids, and metabolites. Their characteristics and microbiome profiles are yet to be explored in the context of in vitro salivary polymicrobial biofilm. This pilot study aimed to compare the profiles of BEVs from salivary biofilm cultured on a 2D tissue culture plate and 3D melt electrowritten medical-grade polycaprolactone (MEW mPCL) scaffold. BEVs derived from MEW mPCL biofilm exhibited enhanced purity and yield without altered EV morphology and lipopolysaccharide (LPS) content, with enriched BEVs-associated DNA from Capnocytophaga, porphyromonas, and veillonella genus. Moreover, compared to saliva controls, MEW mPCL BEVs showed comparable DNA expression of Tannerella forsythia, and Treponema denticola and significantly higher expression in Porphyromonas gingivalis, Eikenella corrodens and Lactobacillus acidophilus. Together, these findings highlight a more detailed microbial profile with BEVs derived from salivary biofilms cultured on 3D MEW PCL scaffolds, which facilitates an effective in vitro model with a greater resemblance to naturally occurring biofilms.

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.

An Oral H2S Responsive Cu5.4O Nanozyme Platform with Strong ROS/H2S Scavenging Capacity for the Treatment of Colitis

Inflammatory bowel disease involves excess reactive oxygen species (ROS) and hydrogen sulfide (H2S) at inflammatory sites. Nanozyme-mediated ROS and H2S scavenging therapy is promising for colitis treatment. Here, we synthesized a multiple ROS scavenging Cu5.4O nanoparticle and first explored its H2S scavenging capacity. Chitosan oligosaccharide modified with alpha-lipoic acid was coated on the nanoparticles to further enhance the H2S scavenging capacity. Furthermore, calcium alginate was coated on the surface to develop an oral nanoplatform (Cu5.4O@SAG) possessing dual-pH/H2S-responsive release characteristics. Importantly, Cu5.4O@SAG exhibited enrichment at the colonic inflammation site and relieved the inflammatory index, containing the recovery of colon length, spleen index, liver index, and body weight, as well as inflammatory cell infiltration. In vivo and in vitro experiments revealed the dual ROS and H2S scavenging capacities of the nanoplatform. Additionally, Cu5.4O@SAG regulated tight junctions, mucus layers, and gut microbiota, which was accompanied by the downregulation of inflammatory cytokines. Notably, Cu5.4O@SAG also had excellent biocompatibility. In conclusion, this oral multiple-scavenging nanozyme platform provides a new and safe paradigm for the development of nanozymes for colitis treatment.

Anti-inflammatory Effects of Membrane Vesicles from Eubacterium rectale via the NLRP3 Signal Pathway

Eubacterium rectale (E. rectale) has the ability to attenuate systemic and intestinal inflammation. Its naturally secreted membrane vesicles (MVs) likely play a crucial role in this process. The objective of this study is to investigate the anti-inflammatory effects of E. rectale and its membrane vesicles (MVs). An inflammation model was established by inducing an inflammatory response in Raw 264.7 cells using lipopolysaccharide (LPS). Subsequently, the cells were pre-treated with E. rectale and its MVs, and the expression levels of IL-1β, IL-6, TNF-α, and IL-10 in the cells were then detected using RT-qPCR. ELISA was used to measure the secretion levels of IL-1β, while western blot analysis was employed to assess the expression of key proteins in the IL-1β pathway, specifically ASC, Caspase 1, and NLRP3. The results revealed that both E. rectale and its MVs significantly reduced the expression of the inflammatory cytokines IL-1β and TNF-α in Raw 264.7 cells, which were induced by LPS. Additionally, they markedly upregulated the expression of the anti-inflammatory cytokine IL-10 and suppressed IL-1β expression via the NLRP3-Caspase 1-ASC signaling pathway. These findings suggest that E. rectale, through its membrane vesicles, can attenuate LPS-induced NLRP3 inflammasome activation, thereby mitigating the inflammatory response in Raw 264.7 cells.

Respiratory Flora Intervention: A New Strategy for the Prevention and Treatment of Occupationally Related Respiratory Allergy in Healthcare Workers

Occupational allergic respiratory disease in healthcare workers due to occupational exposure has received widespread attention. At the same time, evidence of altered respiratory flora associated with the development of allergy has been found in relevant epidemiologic studies. It is of concern that the composition of nasopharyngeal flora in healthcare workers differs significantly from that of non-healthcare workers due to occupational factors, with a particularly high prevalence of carriage of pathogenic and drug-resistant bacteria. Recent studies have found that interventions with upper respiratory tract probiotics can significantly reduce the incidence of respiratory allergies and infections. We searched PubMed and other databases to describe the burden of allergic respiratory disease and altered respiratory flora in healthcare workers in this narrative review, and we summarize the mechanisms and current state of clinical research on the use of flora interventions to ameliorate respiratory allergy, with the aim of providing a new direction for protecting the respiratory health of healthcare workers.

Insights into Microbiota-Host Crosstalk in the Intestinal Diseases Mediated by Extracellular Vesicles and Their Encapsulated MicroRNAs

Microorganisms that colonize the intestine communicate with the host in various ways and affect gut function and health. Extracellular vesicles (EVs), especially their encapsulated microRNAs (miRNAs), participate in the complex and precise regulation of microbiota-host interactions in the gut. These roles make miRNAs critically important for the prevention, diagnosis, and treatment of intestinal diseases. Here, we review the current knowledge on how different sources of EVs and miRNAs, including those from diets, gut microbes, and hosts, maintain gut microbial homeostasis and improve the intestinal barrier and immune function. We further highlight the roles of EVs and miRNAs in intestinal diseases, including diarrhea, inflammatory bowel disease, and colorectal cancer, thus providing a perspective for the application of EVs and miRNAs in these diseases.

Rumen-mammary gland axis and bacterial extracellular vesicles: Exploring a new perspective on heat stress in dairy cows

Heat stress poses a significant threat to the global livestock industry, particularly impacting dairy cows due to their higher metabolic heat production and increased susceptibility. The rumen microbiota plays a crucial role in regulating heat stress in dairy cows. Moreover, the rumen-mammary gland axis has been recently unveiled, indicating that rumen bacteria and their metabolites can influence mammary gland health and function. Extracellular vesicles, cell-derived vesicles, are known to carry various biomolecules and mediate intercellular communication and immune modulation. This review proposes the hypothesis that heat stress poses a threat to dairy cows via the rumen-mammary gland axis by regulating rumen microbiota and their secreted extracellular vesicles. It summarizes existing knowledge on bacterial extracellular vesicles and the rumen-mammary gland axis, suggesting that targeting the rumen microbiota and their extracellular vesicles, while enhancing mammary gland health through this axis, could be a promising strategy for preventing and alleviating heat stress in dairy cows. The aim of this review is to offer new insights and guide future research and development efforts concerning heat stress in dairy cows, thereby contributing to a deeper understanding of its pathogenesis and potential interventions.

Host metabolic inflammation fueled by bacterial DNA

Metabolic diseases, characterized by chronic low-grade inflammation, exhibit a compromised gut barrier allowing the translocation of bacteria-derived products to bloodstream and distant metabolic organs. Bacterial DNA can be detected in metabolic tissues during the onset of these diseases, highlighting its role in the development of metabolic diseases. Extracellular vesicles (EVs) are involved in the delivery of bacterial DNA to the local tissues, and its sensing by the host triggers local and system inflammation. Understanding bacterial DNA translocation and its induced inflammation is crucial in deciphering metabolic disease pathways. Here, we delve into the mechanisms dictating the interaction between host physiology and bacterial DNA, focusing on its origin and delivery, host immune responses against it, and its roles in metabolic disorders.

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.

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.

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.

Extracellular vesicles biogenesis and uptake concepts: A comprehensive guide to studying host-pathogen communication

The study of host-pathogen interactions has increased considerably in recent decades. This intercellular communication has been mediated by extracellular vesicles (EVs) that play an important role during the interaction. EVs are particles of lipid bilayer and described in different types of cells, eukaryotic or prokaryotic. Depending on their biogenesis they are described as exosomes (derived from multivesicular bodies) and microvesicles (derived from the plasma membrane). The EVs carry biomolecules, including nucleic acids, lipids, and proteins that can be released or internalized by other cells in different pathways (endocytosis, macropinocytosis, phagocytosis, or membrane fusion) in the process described as uptake. The balance between biogenesis and uptake of EVs could modify physiological and pathophysiological processes of the cell. This review is focusing on the dynamic roles of release and capture of EVs during host-pathogen interaction. We also do a critical analysis of methodologies for obtaining and analyzing EVs. Finally, we draw attention to critical points to be considered in EV biogenesis and uptake studies.

Bifidobacterium lactis-Derived Vesicles Attenuate Hippocampal Neuroinflammation by Targeting IL-33 to Regulate FoxO6/P53 Signaling

BACKGROUND

Hippocampal Neuroinflammation (HNF) is a critical driver of cognitive impairment. The lipopolysaccharide (LPS) accumulate amyloid beta (Aβ) and lead to HNF. The Bifidobacterium lactis (BL) 99 have anti-inflammatory ability. However, whether BL99-derived microbiota-derived vesicles (MV) could alleviate LPS-induced HNF remains unclear.

METHODS

To investigate, we used ultrafiltration with ultracentrifuge to extract BL99-derived-MV (BL99-MV). We used hippocampal neuronal HT22 cells (HT22) to establish the LPS-induced HNF model, and explored whether BL99-MV alleviate LPS-induced HNF.

RESULTS

The confocal microscopy showed that BL99-MV were taken up by HT22 and reduced the oxidative stress (ROS) level. The PCR showed that BL99-MV up-regulate IL-10 level, and down-regulate TNF-α, IL-1β, and IL-6. Transcriptomic analysis revealed 4127 differentially expressed genes, with 2549 genes upregulated and 1578 genes downregulated in the BL99-MV group compared to the LPS group. Compared to the LPS group, BL99-MV decreased FoxO6, IL-33, P53, and NFκB expression, but increased FoxO1 and Bcl2 expression. The WB showed that BL99-MV modulated NFκB, FoxO6, P53, Caspase9, and Caspase3 protein expression by reducing IL-33 expression in HT22. The findings demonstrated IL-33 as a regulator for FoxO6/P53 signaling.

CONCLUSIONS

Here, we hypothesized that BL99-MV alleviated LPS-induced HNF to promote HT22 survival and synaptic development by regulating FoxO6/P53 signaling by targeting IL-33.

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.

Lactobacillus rhamnosus GG-derived extracellular vesicles promote wound healing via miR-21-5p-mediated re-epithelization and angiogenesis

Extracellular vesicles (EVs), especially those derived from stem cells, have emerged as a novel treatment for promoting wound healing in regenerative medicine. However, the clinical application of mammalian cells-derived EVs is hindered by their high cost and low yields. Inspired by the ability of EVs to mediate interkingdom communication, we explored the therapeutic potential of EVs released by the probiotic strain Lactobacillus rhamnosus GG (LGG) in skin wound healing and elucidated the underlying mechanism involved. Using full-thickness skin wound-healing mouse models, we found that LGG-EVs accelerated wound healing procedures, including increased re-epithelialization and promoted angiogenesis. Using in vitro experiments, we further demonstrated that LGG-EVs boosted the proliferation and migration capacities of both epithelial and endothelial cells, as well as promoted endothelial tube formation. miRNA profiling analysis revealed that miR-21-5p was highly enriched in LGG-EVs and LGG-EV treatment significantly increased miR-21-5p level in recipient cells. Mechanically, LGG-EVs induced regulatory effects via miR-21-5p mediated metabolic signaling rewiring. Our results suggest that EVs derived from LGG could serve as a promising candidate for accelerating wound healing and possibly for treating chronic and impaired healing conditions.

Intestinal Lactobacillus murinus-derived small RNAs target porcine polyamine metabolism

Gut microbiota plays a vital role in host metabolism; however, the influence of gut microbes on polyamine metabolism is unknown. Here, we found germ-free models possess elevated polyamine levels in the colon. Mechanistically, intestinal Lactobacillus murinus-derived small RNAs in extracellular vesicles down-regulate host polyamine metabolism by targeting the expression of enzymes in polyamine metabolism. In addition, Lactobacillus murinus delays recovery of dextran sodium sulfate-induced colitis by reducing polyamine levels in mice. Notably, a decline in the abundance of small RNAs was observed in the colon of mice with colorectal cancer (CRC) and human CRC specimens, accompanied by elevated polyamine levels. Collectively, our study identifies a specific underlying mechanism used by intestinal microbiota to modulate host polyamine metabolism, which provides potential intervention for the treatment of polyamine-associated diseases.

Extracellular vesicles of Bacteroides uniformis induce M1 macrophage polarization and aggravate gut inflammation during weaning

Weaning process is commonly associated with gastrointestinal inflammation and dysbiosis of the intestinal microbes. In particular, the impact of gut bacteria and extracellular vesicles on the etiology of intestinal inflammation during weaning is not well understood. We have uncovered a potential link between gut inflammation and the corresponding variation of macrophage bacterial sensing and pro-inflammatory polarization during the weaning process of piglets through single-cell transcriptomic analyses. We conducted a comprehensive analysis of bacterial distribution across the gastrointestinal tract and pinpointed Bacteroides uniformis enriching in piglets undergoing weaning. Next, we found out that exposure to B. uniformis-derived extracellular vesicles (BEVs) exacerbated gut inflammation in a murine colitis model while recruiting and polarizing intestinal macrophages toward a pro-inflammatory phenotype. BEVs modulated the function of macrophages cultured in vitro by suppressing the granulocyte-macrophage colony-stimulating factor/signal transducer and activator of transcription 5/arginase 1 pathway, thereby affecting polarization toward an M1-like state. The effects of BEVs were verified both in the macrophage clearance murine model and by using an adoptive transfer assay. Our findings highlight the involvement of BEVs in facilitating the polarization of pro-inflammatory macrophages and promoting gut inflammation during weaning.

The emerging role of bacterial extracellular vesicles in human cancers

Bacterial extracellular vesicles (BEVs) have emerged as pivotal mediators between bacteria and host. In addition to being crucial players in host homeostasis, they have recently been implicated in disease pathologies such as cancer. Hence, the study of BEVs represents an intriguing and rapidly evolving field with substantial translational potential. In this review, we briefly introduce the fundamentals of BEV characteristics, cargo and biogenesis. We emphatically summarize the current relationship between BEVs across various cancer types, illustrating their role in tumorigenesis, treatment responses and patient survival. We further discuss the inherent advantages of BEVs, such as stability, abundance and specific cargo profiles, that make them attractive candidates for non-invasive diagnostic and prognostic approaches. The review also explores the potential of BEVs as a strategy for cancer therapy, considering their ability to deliver therapeutic agents, modulate the tumour microenvironment (TME) and elicit immunomodulatory responses. Understanding the clinical significance of BEVs may lead to the development of better-targeted and personalized treatment strategies. This comprehensive review evaluates the current progress surrounding BEVs and poses questions to encourage further research in this emerging field to harness the benefits of BEVs for their full potential in clinical applications against cancer.

Cucurbitacin IIb alleviates colitis via regulating gut microbial composition and metabolites

Cucurbitacin IIb, a member of the triterpenoid family, exerts beneficial effects on intestinal diseases, including enteritis and bacillary dysentery. However, its effects and mechanisms of action on colitis have not yet been explored. In this study, we used a mouse model of dextran sulfate sodium (DSS)-induced colitis and explored the effects of cucurbitacin IIb on colitis symptoms, inflammatory responses, microbiota, and metabolite profiles. The results showed that cucurbitacin IIb alleviated colitis symptoms including body weight loss, an increase in the disease activity index, and elevated levels of myeloperoxidase and eosinophil peroxidase content. Additionally, it ameliorated intestinal morphology impairment, reduced the phosphorylation of NFκB protein, and mitigated accumulation of pro-inflammatory cytokines IL-6 and IL-1β. Furthermore, cucurbitacin IIb alleviated alterations in gut microbial composition and metabolites in DSS-treated mice. However, antibiotic treatment diminishes the beneficial effects of cucurbitacin IIb on colitis. We further found that transplantation of fresh feces or heat-inactivated feces from mice treated with cucurbitacin IIb to DSS-treated mice alleviated colitis, similar to the effects of cucurbitacin IIb. Collectively, our results suggest that cucurbitacin IIb exerted anti-inflammatory effects in colitis by regulating the microbiota composition and metabolites, thereby alleviating colitis symptoms.

Bacteria and Allergic Diseases

Microorganisms colonize all barrier tissues and are present on the skin and all mucous membranes from birth. Bacteria have many ways of influencing the host organism, including activation of innate immunity receptors by pathogen-associated molecular patterns and synthesis of various chemical compounds, such as vitamins, short-chain fatty acids, bacteriocins, toxins. Bacteria, using extracellular vesicles, can also introduce high-molecular compounds, such as proteins and nucleic acids, into the cell, regulating the metabolic pathways of the host cells. Epithelial cells and immune cells recognize bacterial bioregulators and, depending on the microenvironment and context, determine the direction and intensity of the immune response. A large number of factors influence the maintenance of symbiotic microflora, the diversity of which protects hosts against pathogen colonization. Reduced bacterial diversity is associated with pathogen dominance and allergic diseases of the skin, gastrointestinal tract, and upper and lower respiratory tract, as seen in atopic dermatitis, allergic rhinitis, chronic rhinosinusitis, food allergies, and asthma. Understanding the multifactorial influence of microflora on maintaining health and disease determines the effectiveness of therapy and disease prevention and changes our food preferences and lifestyle to maintain health and active longevity.

Serum Extracellular Vesicles Reveal Metabolic Responses to Time-Restricted Feeding in High Fat Diet-Induced Obesity in Male Mice

Objective

Extracellular vesicle (EV) secretion and cargo composition are dysregulated in metabolic diseases. This study aimed to identify changes in the EV size profile and protein cargoes in diet-induced obesity following time-restricted feeding (TRF) and to establish the role of EVs in obesity-related metabolic responses.

Methods

Mice were fed a high-fat diet (HFD) for 18 weeks prior to being placed either ad libitum or a time-restricted feeding for an additional 10 weeks. Mice on a normal chow ad libitum served as the control. The TRF group had food available for 10 hours and fasted for 14 hours per day.

Results

The serum EV size profile and amount displayed sex- and age-dependent changes in HFD-induced obesity, with age reducing EV amounts. HFD decreased small EV populations and increased larger EV populations, while TRF reversed these changes. Quantitative proteomic analysis showed that the abundance and composition of EV proteins changed in response to both acute stimulation with lipopolysaccharides (LPS) and HFD. Gene ontology analysis identified specific sets of EV proteins and their involved biological processes, reflecting the effect of LPS and HFD, as well as the reversal effect of TRF on metabolic and inflammatory pathways. EV proteins altered by HFD and those reversed by TRF had low protein overlap but significant functional overlap in biological processes. TRF activated the PPAR signaling pathway and the AKT-mTOR signaling pathway. The most significant impacts of HFD and TRF were observed on lipoprotein and carbohydrate metabolism, complement system, and neutrophil degranulation. The reversal effect of TRF on the complement system was pathway-specific, significantly activating the lectin complement pathway and restoring neutrophil degranulation.

Conclusion

Our data indicate that EVs are involved in diet-induced metabolic and inflammatory responses. Different EV populations may carry distinct sets of proteins involved in specific biological processes, thereby regulating diverse metabolic pathways efficiently.

Intestinal flora and bile acid interactions impact the progression of diabetic kidney disease

In recent years, with the rapid development of omics technologies, researchers have shown that interactions between the intestinal flora and bile acids are closely related to the progression of diabetic kidney disease (DKD). By regulating bile acid metabolism and receptor expression, the intestinal flora affects host metabolism, impacts the immune system, and exacerbates kidney injury in DKD patients. To explore interactions among the gut flora, bile acids and DKD, as well as the related mechanisms, in depth, in this paper, we review the existing literature on correlations among the gut flora, bile acids and DKD. This review also summarizes the efficacy of bile acids and their receptors as well as traditional Chinese medicines in the treatment of DKD and highlights the unique advantages of bile acid receptors in DKD treatment. This paper is expected to reveal a new and important potential strategy for the clinical treatment of DKD.

Role of probiotic extracellular vesicles in inter-kingdom communication and current technical limitations in advancing their therapeutic utility

Diverse functions of probiotic extracellular vesicles (EVs) have been extensively studied over the past decade, proposing their role in inter-kingdom communication. Studies have explored their therapeutic role in pathophysiological processes ranging from cancer, immunoregulation, and ulcerative colitis to stress-induced depression. These studies have highlighted the significant and novel potential of probiotic EVs for therapeutic applications, offering immense promise in addressing several unmet clinical needs. Additionally, probiotic EVs are being explored as vehicles for targeted delivery approaches. However, the realization of clinical utility of probiotic EVs is hindered by several knowledge gaps, pitfalls, limitations, and challenges, which impede their wider acceptance by the scientific community. Among these, limited knowledge of EV biogenesis, markers and regulators in bacteria, variations in cargo due to culture conditions or EV isolation method, and lack of proper understanding of gut uptake and demonstration of in vivo effect are some important issues. This review aims to summarize the diverse roles of probiotic EVs in health and disease conditions. More importantly, it discusses the significant knowledge gaps and limitations that stand in the way of the therapeutic utility of probiotic EVs. Furthermore, the importance of addressing these gaps and limitations with technical advances such as rigorous omics has been discussed.

Yin-Yang: two sides of extracellular vesicles in inflammatory diseases

The concept of Yin-Yang, originating in ancient Chinese philosophy, symbolizes two opposing but complementary forces or principles found in all aspects of life. This concept can be quite fitting in the context of extracellular vehicles (EVs) and inflammatory diseases. Over the past decades, numerous studies have revealed that EVs can exhibit dual sides, acting as both pro- and anti-inflammatory agents, akin to the concept of Yin-Yang theory (i.e., two sides of a coin). This has enabled EVs to serve as potential indicators of pathogenesis or be manipulated for therapeutic purposes by influencing immune and inflammatory pathways. This review delves into the recent advances in understanding the Yin-Yang sides of EVs and their regulation in specific inflammatory diseases. We shed light on the current prospects of engineering EVs for treating inflammatory conditions. The Yin-Yang principle of EVs bestows upon them great potential as, therapeutic, and preventive agents for inflammatory diseases.

Epithelial barrier dysfunction and microbial dysbiosis: exploring the pathogenesis and therapeutic strategies for Crohn's disease

Crohn's disease (CD), a chronic gastrointestinal inflammatory disease, is becoming more widespread worldwide. Crohn's disease is caused by gut microbiota changes, genetics, environmental stresses, and immunological responses. Current treatments attempt to achieve long-term remission and avoid complications, delaying disease progression. Immunosuppressive measures and combination medicines should be started early for high-risk patients. These medicines monitor inflammatory indicators and adjust as needed. The epithelial barrier helps defend against physical, chemical, and immunological threats. When tissues' protective barrier breaks down, the microbiome may reach the layer underneath. Unbalanced microbial populations and inflammation impair healing and adjustment. Inflammatory cells infiltrating sensitive tissues aggravate the damage and inflammation. This approach promotes chronic inflammatory diseases. The epithelial barrier hypothesis states that hereditary and environmental variables cause epithelial tissue inflammation. This review focuses on how epithelial barrier break-down and microbial dysbiosis cause Crohn's disease and current advances in understanding the epithelial barrier, immune system, and microbiome. Additionally, investigate treatments that restore barrier integrity and promote microbial balance. Overall, it stresses the role of epithelial barrier failure and microbial dysbiosis in Crohn's disease development and discusses current advances in understanding the barrier, immunological responses, and microbiota.

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.

Roseburia intestinalis-derived extracellular vesicles ameliorate colitis by modulating intestinal barrier, microbiome, and inflammatory responses

Inflammatory bowel disease (IBD) is a chronic disorder characterized by recurrent gastrointestinal inflammation, lacking a precise aetiology and definitive cure. The gut microbiome is vital in preventing and treating IBD due to its various physiological functions. In the interplay between the gut microbiome and human health, extracellular vesicles secreted by gut bacteria (BEVs) are key mediators. Herein, we explore the role of Roseburia intestinalis (R)-derived EVs (R-EVs) as potent anti-inflammatory mediators in treating dextran sulfate sodium-induced colitis. R was selected as an optimal BEV producer for IBD treatment through ANCOM analysis. R-EVs with a 76 nm diameter were isolated from R using a tangential flow filtration system. Orally administered R-EVs effectively accumulated in inflamed colonic tissues and increased the abundance of Bifidobacterium on microbial changes, inhibiting colonic inflammation and prompting intestinal recovery. Due to the presence of Ile-Pro-Ile in the vesicular structure, R-EVs reduced the DPP4 activity in inflamed colonic tissue and increased the active GLP-1, thereby downregulating the NFκB and STAT3 via the PI3K pathway. Our results shed light on the impact of BEVs on intestinal recovery and gut microbiome alteration in treating IBD.

The Role of the Intestinal Flora and Its Derivatives in Neurocognitive Disorders: A Narrative Review from Surgical Perspective

Perioperative neurocognitive dysfunction is a significant concern for population health, impacting postoperative recovery and increasing the financial burden on patients. With an increasing number of surgical procedures being performed, the prevention and management of perioperative neurocognitive dysfunction have garnered significant attention. While factors such as age, lifestyle, genetics, and education are known to influence the development of cognitive dysfunction, recent research has highlighted the role of the gut microbiota in neurological health. An increased abundance of pro-inflammatory gut microbiota can trigger and worsen neuroinflammation, neuronal cell damage, and impaired cellular autophagy. Moreover, the inflammation-promoting gut microbiota can disrupt immune function, impair neuroautophagy, and affect the production and circulation of extracellular vesicles and neurotransmitters. These factors collectively play a role in the onset and advancement of cognitive impairment. This narrative review delves into the molecular mechanisms through which gut microbiota and their derivatives contribute to cognitive impairment, focusing on the impact of anesthesia surgery, changes in gut microbial populations, and perioperative cognitive impairment associations. The study suggests that alterations in the abundance of various bacterial species and their metabolites pre- and post-surgery may be linked to postoperative cognitive impairment. Furthermore, the potential of probiotics or prebiotics in addressing cognitive impairment is discussed, offering a promising avenue for investigating the treatment of perioperative neurocognitive disorders.

Proteomic Analysis of Caco-2 Cells Disrupted by EcN 1917-Derived OMVs Reveals Molecular Information on Bacteria-Mediated Cancer Cell Migration

Escherichia coli Nissle 1917 (EcN 1917) exhibits distinct tumor-targeting activity, and early studies demonstrated that outer membrane vesicles (OMVs) mediate bacteria-host interactions. To decipher the molecular mechanism underlying the interaction between EcN 1917 and host cells via OMV-mediated communication, we investigated the phenotypic changes in Caco-2 cells perturbed by EcN 1917-derived OMVs and constructed proteomic maps of the EcN 1917-derived OMV components and OMV-perturbed host cells. Our findings revealed that the size of the EcN 1917-derived OMV proteome increased 4-fold. Treatment with EcN 1917-derived OMVs altered the proteomic and phosphoproteomic profiles of host cells. Importantly, for the first time, we found that treatment with EcN 1917-derived OMVs inhibited cancer cell migration by suppressing the expression of ANXA9. In addition, phosphoproteomic data suggested that the ErbB pathway may be involved in OMV-mediated cell migration. Taken together, our study provides valuable data for further investigations of OMV-mediated bacteria-host interactions and offers great insights into the underlying mechanism of probiotic-assisted colorectal cancer therapy.

Characterisation of LPS+ bacterial extracellular vesicles along the gut-hepatic portal vein-liver axis

Gut microbiome dysbiosis is a major contributing factor to several pathological conditions. However, the mechanistic understanding of the communication between gut microbiota and extra-intestinal organs remains largely elusive. Extracellular vesicles (EVs), secreted by almost every form of life, including bacteria, could play a critical role in this inter-kingdom crosstalk and are the focus of present study. Here, we present a novel approach for isolating lipopolysaccharide (LPS)+ bacterial extracellular vesicles (bEVLPS) from complex biological samples, including faeces, plasma and the liver from lean and diet-induced obese (DIO) mice. bEVLPS were extensively characterised using nanoparticle tracking analyses, immunogold labelling coupled with transmission electron microscopy, flow cytometry, super-resolution microscopy and 16S sequencing. In liver tissues, the protein expressions of TLR4 and a few macrophage-specific biomarkers were assessed by immunohistochemistry, and the gene expressions of inflammation-related cytokines and their receptors (n = 89 genes) were measured using a PCR array. Faecal samples from DIO mice revealed a remarkably lower concentration of total EVs but a significantly higher percentage of LPS+ EVs. Interestingly, DIO faecal bEVLPS showed a higher abundance of Proteobacteria by 16S sequencing. Importantly, in DIO mice, a higher number of total EVs and bEVLPS consistently entered the hepatic portal vein and subsequently reached the liver, associated with increased expression of TLR4, macrophage markers (F4/80, CD86 and CD206), cytokines and receptors (Il1rn, Ccr1, Cxcl10, Il2rg and Ccr2). Furthermore, a portion of bEVLPS escaped liver and entered the peripheral circulation. In conclusion, bEV could be the key mediator orchestrating various well-established biological effects induced by gut bacteria on distant organs.

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.

Lysis-Free Isolation and Direct Amplification of Pathogenic Bacterial DNA Using Diatom Frustules

DNA has been implicated as an important biomarker for the diagnosis of bacterial infections. Herein, we developed a streamlined methodology that uses diatom frustules (DFs) to liberate and capture bacterial DNA and allows direct downstream amplification tests without any lysis, washing, or elution steps. Unlike most conventional DNA isolation methods that rely on cell lysis to release bacterial DNA, DFs can trigger the oxidative stress response of bacterial cells to promote bacterial membrane vesicle formation and DNA release by generating reactive oxygen species in aqueous solutions. Due to the hierarchical porous structure, DFs provided high DNA capture efficiency exceeding 80% over a wide range of DNA amounts from 10 pg to 10 ng, making only 10 μg DFs sufficient for each test. Since laborious liquid handling steps are not required, the entire DNA sample preparation process using DFs can be completed within 3 min. The diagnostic use of this DF-based methodology was illustrated, which showed that the DNA of the pathogenic bacteria in serum samples was isolated by DFs and directly detected using polymerase chain reaction (PCR) at concentrations as low as 102 CFU/mL, outperforming the most used approaches based on solid-phase DNA extraction. Furthermore, most of the bacterial cells were still alive after DNA isolation using DFs, providing the possibility of recycling samples for storage and further diagnosis. The proposed DF-based methodology is anticipated to simplify bacterial infection diagnosis and be broadly applied to various medical diagnoses and biological research.

Evolution and the critical role of the microbiota in the reduced mental and physical health associated with low socioeconomic status (SES)

The evolution of the gut-microbiota-brain axis in animals reveals that microbial inputs influence metabolism, the regulation of inflammation and the development of organs, including the brain. Inflammatory, neurodegenerative and psychiatric disorders are more prevalent in people of low socioeconomic status (SES). Many aspects of low SES reduce exposure to the microbial inputs on which we are in a state of evolved dependence, whereas the lifestyle of wealthy citizens maintains these exposures. This partially explains the health deficit of low SES, so focussing on our evolutionary history and on environmental and lifestyle factors that distort microbial exposures might help to mitigate that deficit. But the human microbiota is complex and we have poor understanding of its functions at the microbial and mechanistic levels, and in the brain. Perhaps its composition is more flexible than the microbiota of animals that have restricted habitats and less diverse diets? These uncertainties are discussed in relation to the encouraging but frustrating results of attempts to treat psychiatric disorders by modulating the microbiota.

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

Omics-based approaches for discovering active ingredients and regulating gut microbiota of Actinidia arguta exosome-like nanoparticles

Exosome-like nanoparticles (ELNs) are novel naturally occurring plant ultrastructures and contain unique bioactive components. However, the potential applications and biological functions of plant ELNs, especially in the context of health promotion and disease prevention, remain largely unexplored. This study aimed to explore the biological activities and functional mechanisms of Actinidia arguta-derived exosome-like nanoparticles (AAELNs). We reported the development of AAELNs, which possess particle sizes of 157.8 nm and a negative surface charge of -23.07 mV, uptaking by RAW264.7 cells, and reduction of oxidative stress by decreasing the activity of GSH-Px and T-SOD and increasing the content of MDA. Through the use of high-throughput sequencing technology, 12 known miRNA families and 23 additional miRNAs were identified in AAELNs, GO and KEGG term enrichment analysis revealed the potential of AAELNs-miRNAs in modulating neural-relevant behaviors. Additionally, LC-MS/MS analysis detected a total of 32 major lipid classes, 430 lipid subclasses, and 1345 proteins in AAELNs. Furthermore, in vivo fluorescence disappearance and in vitro fermentation experiments demonstrated that AAELNs were able to enter the colon and improve the microbial structure. These findings suggest that AAELNs could serve as nanoshuttles in food, potentially offering health-enhancing properties.

Modulation of Serotonin-Related Genes by Extracellular Vesicles of the Probiotic Escherichia coli Nissle 1917 in the Interleukin-1β-Induced Inflammation Model of Intestinal Epithelial Cells

Inflammatory bowel disease (IBD) is a chronic inflammatory condition involving dysregulated immune responses and imbalances in the gut microbiota in genetically susceptible individuals. Current therapies for IBD often have significant side-effects and limited success, prompting the search for novel therapeutic strategies. Microbiome-based approaches aim to restore the gut microbiota balance towards anti-inflammatory and mucosa-healing profiles. Extracellular vesicles (EVs) from beneficial gut microbes are emerging as potential postbiotics. Serotonin plays a crucial role in intestinal homeostasis, and its dysregulation is associated with IBD severity. Our study investigated the impact of EVs from the probiotic Nissle 1917 (EcN) and commensal E. coli on intestinal serotonin metabolism under inflammatory conditions using an IL-1β-induced inflammation model in Caco-2 cells. We found strain-specific effects. Specifically, EcN EVs reduced free serotonin levels by upregulating SERT expression through the downregulation of miR-24, miR-200a, TLR4, and NOD1. Additionally, EcN EVs mitigated IL-1β-induced changes in tight junction proteins and oxidative stress markers. These findings underscore the potential of postbiotic interventions as a therapeutic approach for IBD and related pathologies, with EcN EVs exhibiting promise in modulating serotonin metabolism and preserving intestinal barrier integrity. This study is the first to demonstrate the regulation of miR-24 and miR-200a by probiotic-derived EVs.

Immunomodulatory properties of Bacillus subtilis extracellular vesicles on rainbow trout intestinal cells and splenic leukocytes

Extracellular vesicles (EVs) are cell-derived membrane-surrounded vesicles that carry bioactive molecules. Among EVs, outer membrane vesicles (OMVs), specifically produced by Gram-negative bacteria, have been extensively characterized and their potential as vaccines, adjuvants or immunotherapeutic agents, broadly explored in mammals. Nonetheless, Gram-positive bacteria can also produce bilayered spherical structures from 20 to 400 nm involved in pathogenesis, antibiotic resistance, nutrient uptake and nucleic acid transfer. However, information regarding their immunomodulatory potential is very scarce, both in mammals and fish. In the current study, we have produced EVs from the Gram-positive probiotic Bacillus subtilis and evaluated their immunomodulatory capacities using a rainbow trout intestinal epithelial cell line (RTgutGC) and splenic leukocytes. B. subtilis EVs significantly up-regulated the transcription of several pro-inflammatory and antimicrobial genes in both RTgutGC cells and splenocytes, while also up-regulating many genes associated with B cell differentiation in the later. In concordance, B. subtilis EVs increased the number of IgM-secreting cells in splenocyte cultures, while at the same time increased the MHC II surface levels and antigen-processing capacities of splenic IgM+ B cells. Interestingly, some of these experiments were repeated comparing the effects of B. subtilis EVs to EVs obtained from another Bacillus species, Bacillus megaterium, identifying important differences. The data presented provides evidence of the immunomodulatory capacities of Gram-positive EVs, pointing to the potential of B. subtilis EVs as adjuvants or immunostimulants for aquaculture.

Microorganism-derived extracellular vesicles: emerging contributors to female reproductive health

Extracellular vesicles (EVs) are cell-derived nanoparticles that carry small molecules, nucleic acids, and proteins long distances in the body facilitating cell-cell communication. Microorganism-derived EVs mediate communication between parent cells and host cells, with recent evidence supporting their role in biofilm formation, horizontal gene transfer, and suppression of the host immune system. As lipid-bound bacterial byproducts, EVs demonstrate improved cellular uptake and distribution in vivo compared to cell-free nucleic acids, proteins, or small molecules, allowing these biological nanoparticles to recapitulate the effects of parent cells and contribute to a range of human health outcomes. Here, we focus on how EVs derived from vaginal microorganisms contribute to gynecologic and obstetric outcomes. As the composition of the vaginal microbiome significantly impacts women's health, we discuss bacterial EVs from both healthy and dysbiotic vaginal microbiota. We also examine recent work done to evaluate the role of EVs from common vaginal bacterial, fungal, and parasitic pathogens in pathogenesis of female reproductive tract disease. We highlight evidence for the role of EVs in women's health, gaps in current knowledge, and opportunities for future work. Finally, we discuss how leveraging the innate interactions between microorganisms and mammalian cells may establish EVs as a novel therapeutic modality for gynecologic and obstetric indications.

Unveiling clinical applications of bacterial extracellular vesicles as natural nanomaterials in disease diagnosis and therapeutics

Bacterial extracellular vesicles (BEVs) are naturally occurring bioactive membrane-bound nanoparticles released by both gram-negative and gram-positive bacterial species, exhibiting a multifaceted role in mediating host-microbe interactions across various physiological conditions. Increasing evidence supports BEVs as essential mediators of cell-to-cell communicaiton, influencing bacterial pathogenicity, disease mechanisms, and modulating the host immune response. However, the extent to which these BEV-mediated actions can be leveraged to predict disease onset, guide treatment strategies, and determine clinical outcomes remains uncertain, particularly in terms of their clinical translation potentials. This review briefly describes BEV biogenesis and their internalisation by recipient cells and summarises methods for isolation and characterization, essential for understanding their composition and cargo. Further, it discusses the potential of biofluid-associated BEVs as biomarkers for various diseases, spanning both cancer and non-cancerous conditions. Following this, we outline the ongoing human clinical trials of using BEVs for vaccine development. In addition to disease diagnostics, this review explores the emerging research of using natural or engineered BEVs as smart nanomaterials for applications in anti-cancer therapy and bone regeneration. This discussion extends to key factors for unlocking the clinical potential of BEVs, such as standardization of BEV isolation and characterisation, as well as other hurdles in translating these findings to the clinical setting. We propose that addressing these hurdles through collaborative research efforts and well-designed clinical trials holds the key to fully harnessing the clinical potential of BEVs. As this field advances, this review suggests that BEV-based nanomedicine has the potential to revolutionize disease management, paving the way for innovative diagnosis, therapeutics, and personalized medicine approaches. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) from both host cells and bacteria serve as multifunctional biomaterials and are emerging in the fields of biomedicine, bioengineering, and biomaterials. However, the majority of current studies focus on host-derived EVs, leaving a gap in comprehensive research on bacteria-derived EVs (BEVs). Although BEVs offer an attractive option as nanomaterials for drug delivery systems, their unique nanostructure and easy-to-modify functions make them a potential method for disease diagnosis and treatment as well as vaccine development. Our work among the pioneering studies investigating the potential of BEVs as natural nanobiomaterials plays a crucial role in both understanding the development of diseases and therapeutic interventions.

Unravelling the Link between the Gut Microbiome and Autoimmune Kidney Diseases: A Potential New Therapeutic Approach

The gut microbiota and short chain fatty acids (SCFA) have been associated with immune regulation and autoimmune diseases. Autoimmune kidney diseases arise from a loss of tolerance to antigens, often with unclear triggers. In this review, we explore the role of the gut microbiome and how disease, diet, and therapy can alter the gut microbiota consortium. Perturbations in the gut microbiota may systemically induce the translocation of microbiota-derived inflammatory molecules such as liposaccharide (LPS) and other toxins by penetrating the gut epithelial barrier. Once in the blood stream, these pro-inflammatory mediators activate immune cells, which release pro-inflammatory molecules, many of which are antigens in autoimmune diseases. The ratio of gut bacteria Bacteroidetes/Firmicutes is associated with worse outcomes in multiple autoimmune kidney diseases including lupus nephritis, MPO-ANCA vasculitis, and Goodpasture's syndrome. Therapies that enhance SCFA-producing bacteria in the gut have powerful therapeutic potential. Dietary fiber is fermented by gut bacteria which in turn release SCFAs that protect the gut barrier, as well as modulating immune responses towards a tolerogenic anti-inflammatory state. Herein, we describe where the current field of research is and the strategies to harness the gut microbiome as potential therapy.

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

There are a growing number of studies linking the composition of the human microbiome to disease states and treatment responses, especially in the context of cancer. This has raised significant interest in developing microbes and microbial products as cancer immunotherapeutics that mimic or recapitulate the beneficial effects of host-microbe interactions. Bacterial extracellular vesicles (bEVs) are nano-sized, membrane-bound particles secreted by essentially all bacteria species and contain a diverse bioactive cargo of the producing cell. They have a fundamental role in facilitating interactions among cells of the same species, different microbial species, and even with multicellular host organisms in the context of colonization (microbiome) and infection. The interaction of bEVs with the immune system has been studied extensively in the context of infection and suggests that bEV effects depend largely on the producing species. They thus provide functional diversity, while also being nonreplicative, having inherent cell-targeting qualities, and potentially overcoming natural barriers. These characteristics make them highly appealing for development as cancer immunotherapeutics. Both natively secreted and engineered bEVs are now being investigated for their application as immunotherapeutics, vaccines, drug delivery vehicles, and combinations of the above, with promising early results. This suggests that both the intrinsic immunomodulatory properties of bEVs and their ability to be modified could be harnessed for the development of next-generation microbe-inspired therapies. Nonetheless, there remain major outstanding questions regarding how the observed preclinical effectiveness will translate from murine models to primates, and humans in particular. Moreover, research into the pharmacology, toxicology, and mass manufacturing of this potential novel therapeutic platform is still at early stages. In this review, we highlight the breadth of bEV interactions with host cells, focusing on immunologic effects as the main mechanism of action of bEVs currently in preclinical development. We review the literature on ongoing efforts to develop natively secreted and engineered bEVs from a variety of bacterial species for cancer therapy and finally discuss efforts to overcome outstanding challenges that remain for clinical translation.

A promising area of research in medicine: recent advances in properties and applications of Lactobacillus-derived exosomes

Lactobacillus-derived exosomes, small extracellular vesicles released by bacteria, have emerged as a promising area of research in recent years. These exosomes possess a unique structural and functional diversity that allows them to regulate the immune response and promote gut health. The isolation and purification of these exosomes are crucial for their effective use as a therapeutic agent. Several isolation and purification methods have been developed, including differential ultracentrifugation, density gradient centrifugation, and size-exclusion chromatography. Lactobacillus-derived exosomes have been demonstrated to have therapeutic potential in various diseases, such as inflammatory bowel disease, liver disease, and neurological disorders. Moreover, they have been shown to serve as effective carriers for drug delivery. Genetic engineering of these exosomes has also shown promise in enhancing their therapeutic potential. Overall, Lactobacillus-derived exosomes represent a promising area of research for the development of novel therapeutics for immunomodulation, gut health, and drug delivery.

Molecular Mechanisms of Lacticaseibacillus rhamnosus, LGG® Probiotic Function

To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. Lacticaseibacillus rhamnosus LGG® is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG®, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified. In vitro and animal studies have revealed that specific LGG® effector molecules stimulate epithelial cell survival, preserve intestinal barrier integrity, reduce oxidative stress, mitigate excessive mucosal inflammation, enhance IgA secretion, and provide long-term protection through epigenetic imprinting. Pili on the cell surface of LGG® promote adhesion to the intestinal mucosa and ensure close contact to host cells. Extracellular vesicles produced by LGG® recapitulate many of these effects through their cargo of effector molecules. Collectively, the effector molecules of LGG® exert a significant influence on both the gut mucosa and immune system, which promotes intestinal homeostasis and immune tolerance.

The Profound Influence of Gut Microbiome and Extracellular Vesicles on Animal Health and Disease

The animal gut microbiota, comprising a diverse array of microorganisms, plays a pivotal role in shaping host health and physiology. This review explores the intricate dynamics of the gut microbiome in animals, focusing on its composition, function, and impact on host-microbe interactions. The composition of the intestinal microbiota in animals is influenced by the host ecology, including factors such as temperature, pH, oxygen levels, and nutrient availability, as well as genetic makeup, diet, habitat, stressors, and husbandry practices. Dysbiosis can lead to various gastrointestinal and immune-related issues in animals, impacting overall health and productivity. Extracellular vesicles (EVs), particularly exosomes derived from gut microbiota, play a crucial role in intercellular communication, influencing host health by transporting bioactive molecules across barriers like the intestinal and brain barriers. Dysregulation of the gut-brain axis has implications for various disorders in animals, highlighting the potential role of microbiota-derived EVs in disease progression. Therapeutic approaches to modulate gut microbiota, such as probiotics, prebiotics, microbial transplants, and phage therapy, offer promising strategies for enhancing animal health and performance. Studies investigating the effects of phage therapy on gut microbiota composition have shown promising results, with potential implications for improving animal health and food safety in poultry production systems. Understanding the complex interactions between host ecology, gut microbiota, and EVs provides valuable insights into the mechanisms underlying host-microbe interactions and their impact on animal health and productivity. Further research in this field is essential for developing effective therapeutic interventions and management strategies to promote gut health and overall well-being in animals.

Bacterial extracellular vesicles: Modulation of biofilm and virulence properties

Microbial pathogens cause persistent infections by forming biofilms and producing numerous virulence factors. Bacterial extracellular vesicles (BEVs) are nanostructures produced by various bacterial species vital for molecular transport. BEVs include various components, including lipids (glycolipids, LPS, and phospholipids), nucleic acids (genomic DNA, plasmids, and short RNA), proteins (membrane proteins, enzymes, and toxins), and quorum-sensing signaling molecules. BEVs play a major role in forming extracellular polymeric substances (EPS) in biofilms by transporting EPS components such as extracellular polysaccharides, proteins, and extracellular DNA. BEVs have been observed to carry various secretory virulence factors. Thus, BEVs play critical roles in cell-to-cell communication, biofilm formation, virulence, disease progression, and resistance to antimicrobial treatment. In contrast, BEVs have been shown to impede early-stage biofilm formation, disseminate mature biofilms, and reduce virulence. This review summarizes the current status in the literature regarding the composition and role of BEVs in microbial infections. Furthermore, the dual functions of BEVs in eliciting and suppressing biofilm formation and virulence in various microbial pathogens are thoroughly discussed. This review is expected to improve our understanding of the use of BEVs in determining the mechanism of biofilm development in pathogenic bacteria and in developing drugs to inhibit biofilm formation by microbial pathogens. STATEMENT OF SIGNIFICANCE: Bacterial extracellular vesicles (BEVs) are nanostructures formed by membrane blebbing and explosive cell lysis. It is essential for transporting lipids, nucleic acids, proteins, and quorum-sensing signaling molecules. BEVs play an important role in the formation of the biofilm's extracellular polymeric substances (EPS) by transporting its components, such as extracellular polysaccharides, proteins, and extracellular DNA. Furthermore, BEVs shield genetic material from nucleases and thermodegradation by packaging it during horizontal gene transfer, contributing to the transmission of bacterial adaptation determinants like antibiotic resistance. Thus, BEVs play a critical role in cell-to-cell communication, biofilm formation, virulence enhancement, disease progression, and drug resistance. In contrast, BEVs have been shown to prevent early-stage biofilm, disperse mature biofilm, and reduce virulence characteristics.

Extracellular Vesicles: A Crucial Player in the Intestinal Microenvironment and Beyond

The intestinal ecological environment plays a crucial role in nutrient absorption and overall well-being. In recent years, research has focused on the effects of extracellular vesicles (EVs) in both physiological and pathological conditions of the intestine. The intestine does not only consume EVs from exogenous foods, but also those from other endogenous tissues and cells, and even from the gut microbiota. The alteration of conditions in the intestine and the intestinal microbiota subsequently gives rise to changes in other organs and systems, including the central nervous system (CNS), namely the microbiome-gut-brain axis, which also exhibits a significant involvement of EVs. This review first gives an overview of the generation and isolation techniques of EVs, and then mainly focuses on elucidating the functions of EVs derived from various origins on the intestine and the intestinal microenvironment, as well as the impacts of an altered intestinal microenvironment on other physiological systems. Lastly, we discuss the role of microbial and cellular EVs in the microbiome-gut-brain axis. This review enhances the understanding of the specific roles of EVs in the gut microenvironment and the central nervous system, thereby promoting more effective treatment strategies for certain associated diseases.

Distinct compositions and functions of circulating microbial DNA in the peripheral blood compared to fecal microbial DNA in healthy individuals

The crucial function of circulating microbial DNA (cmDNA) in peripheral blood is gaining recognition because of its importance in normal physiology and immunity in healthy individuals. Evidence suggests that cmDNA in peripheral blood is derived from highly abundant, translocating gut microbes. However, the associations with and differences between cmDNA in peripheral blood and the gut microbiome remain unclear. We collected blood, urine, and fecal samples from volunteers to compare their microbial information via 16S rDNA sequencing. The results revealed that, compared with gut microbial DNA, cmDNA in peripheral blood was associated with reduced diversity and a distinct microbiota composition. The cmDNA in the blood reflects the biochemical processes of microorganisms, including synthesis, energy conversion, degradation, and adaptability, surpassing that of fecal samples. Interestingly, cmDNA in blood showed a limited presence of DNA from anaerobes and gram-positive bacteria, which contrast with the trend observed in fecal samples. Furthermore, analysis of cmDNA revealed traits associated with mobile elements and potential pathologies, among others, which were minimal in stool samples. Notably, cmDNA analysis indicated similarities between the microbial functions and phenotypes in blood and urine samples, although greater diversity was observed in urine samples. Source Tracker analysis suggests that gut microbes might not be the main source of blood cmDNA, or a selective mechanism allows only certain microbial DNA into the bloodstream. In conclusion, our study highlights the composition and potential functions associated with cmDNA in peripheral blood, emphasizing its selective presence; however, further research is required to elucidate the mechanisms involved.IMPORTANCEOur research provides novel insights into the unique characteristics and potential functional implications of circulating microbial DNA (cmDNA) in peripheral blood. Unlike other studies that analyzed sequencing data from fecal or blood microbiota in different study cohorts, our comparative analysis of cmDNA from blood, urine, and fecal samples from the same group of volunteers revealed a distinct blood-specific cmDNA composition. We discovered a decreased diversity of microbial DNA in blood samples compared to fecal samples as well as an increased presence of biochemical processes microbial DNA in blood. Notably, we add to the existing knowledge by documenting a reduced abundance of anaerobes and gram-positive bacteria in blood compared to fecal samples according to the analysis of cmDNA and gut microbial DNA, respectively. This observation suggested that a potential selective barrier or screening mechanism might filter microbial DNA molecules, indicating potential selectivity in the translocation process which contrasts with the traditional view that cmDNA primarily originates from random translocation from the gut and other regions. By highlighting these differences, our findings prompt a reconsideration of the origin and role of cmDNA in blood circulation and suggest that selective processes involving more complex biological mechanisms may be involved.

Extracellular vesicles derived from Lactobacillus johnsonii promote gut barrier homeostasis by enhancing M2 macrophage polarization

INTRODUCTION

Diarrheic disease is a common intestinal health problem worldwide, causing great suffering to humans and animals. Precise manipulation strategies based on probiotics to combat diarrheic diseases have not been fully developed.

OBJECTIVES

The aim of this study was to investigate the molecular mechanisms by which probiotics manipulate macrophage against diarrheic disease.

METHODS

Metagenome reveals gut microbiome profiles of healthy and diarrheic piglets. Fecal microbial transplantation (FMT) was employed to explore the causal relationship between gut microbes and diarrhea. The protective role of probiotics and their derived extracellular vesicles (EVs) was investigated in ETEC K88-infected mice. Macrophage depletion was performed to assess the role of macrophages in EVs against diarrhea. Execution of in vitro cell co-culture and transcriptome analyses elucidated the molecular mechanisms by which EVs modulate the macrophage and intestinal epithelial barrier.

RESULTS

Escherichia coli was enriched in weaned diarrheic piglets, while Lactobacillus johnsonii (L. john) showed a negative correlation with Escherichia coli. The transmission of diarrheic illness symptoms was achieved by transferring fecal microbiota, but not metabolites, from diarrheic pigs to germ-free (GF) mice. L. john's intervention prevented the transmission of disease phenotypes from diarrheic piglets to GF mice. L. john also reduces the gut inflammation induced by ETEC K88. The EVs secreted by L. john demonstrated enhanced efficacy in mitigating the adverse impacts induced by ETEC K88 through the modulation of macrophage phenotype. In vitro experiments have revealed that EVs activate M2 macrophages in a manner that shuts down ERK, thereby inhibiting NLRP3 activation in intestinal epithelial cells.

CONCLUSION

Our results reveal that intestinal microbiota drives the onset of diarrheic disease and that probiotic-derived EVs ameliorate diarrheic disease symptoms by modulating macrophage phenotypes. These findings can enhance the advancement of innovative therapeutic approaches for diarrheic conditions based on probiotic-derived EVs.

The proteome of bacterial membrane vesicles in Escherichia coli-a time course comparison study in two different media

Introduction

Bacteria inhabit the in- and outside of the human body, such as skin, gut or the oral cavity where they play an innoxious, beneficial or even pathogenic role. It is well known that bacteria can secrete membrane vesicles (MVs) like eukaryotic cells with extracellular vesicles (EVs). Several studies indicate that bacterial membrane vesicles (bMVs) play a crucial role in microbiome-host interactions. However, the composition of such bMVs and their functionality under different culture conditions are still largely unknown.

Methods

To gain a better insight into bMVs, we investigated the composition and functionality of E. coli (DSM 105380) bMVs from the culture media Lysogeny broth (LB) and RPMI 1640 throughout the different phases of growth (lag-, log- and stationary-phase). bMVs from three time points (8 h, 54 h, and 168 h) and two media (LB and RPMI 1640) were isolated by ultracentrifugation and analyzed using nanoparticle tracking analysis (NTA), cryogenic electron microscopy (Cryo-EM), conventional transmission electron microscopy (TEM) and mass spectrometry-based proteomics (LC-MS/MS). Furthermore, we examined pro-inflammatory cytokines IL-1β and IL-8 in the human monocyte cell line THP-1 upon bMV treatment.

Results

Particle numbers increased with inoculation periods. The bMV morphologies in Cryo-EM/TEM were similar at each time point and condition. Using proteomics, we identified 140 proteins, such as the common bMV markers OmpA and GroEL, present in bMVs isolated from both media and at all time points. Additionally, we were able to detect growth-condition-specific proteins. Treatment of THP-1 cells with bMVs of all six groups lead to significantly high IL-1β and IL-8 expressions.

Conclusion

Our study showed that the choice of medium and the duration of culturing significantly influence both E. coli bMV numbers and protein composition. Our TEM/Cryo-EM results demonstrated the presence of intact E. coli bMVs. Common E. coli proteins, including OmpA, GroEL, and ribosome proteins, can consistently be identified across all six tested growth conditions. Furthermore, our functional assays imply that bMVs isolated from the six groups retain their function and result in comparable cytokine induction.