The role and mechanisms of gram-negative bacterial outer membrane vesicles in inflammatory diseases

NDM-5-carried outer membrane vesicles impair the efficacy of antibiotics against bacterial infections

The intensifying use of antimicrobials in the rapidly growing livestock industry has heightened concerns over the proliferation of antibiotic resistance, particularly among Enterobacteriaceae producing β-lactamase. Elucidating the role of β-lactamase could unlock novel strategies to combat drug-resistant Enterobacteriaceae in livestock and poultry farming. Outer membrane vesicles (OMVs) produced by gram-negative bacteria have the ability to encapsulate and transport components derived from their parental bacteria. This raises the intriguing possibility that OMVs from drug-resistant bacteria could harbor drug-resistance enzymes, thereby conferring protection to susceptible bacteria against antibiotics. Here, we successfully extracted OMVs from New Delhi metallo-β-lactamase-5 (NDM-5)-expressing Escherichia coli and confirmed that these vesicles indeed carry NDM-5 protein. Furthermore, bacterial protection assays showed that these OMVs could cause sensitive bacteria treated with meropenem to restore growth activity, and the degradation of meropenem by the OMVs was verified using high-performance liquid chromatography. Lastly, the survival rate of the OMVs intervention group was significantly lower than that of the drug-treated group in a Galleria mellonella larvae infection model, validating the protective effect of these OMVs on sensitive bacteria and increasing their tolerance to meropenem. These findings illustrate that OMVs can serve as vehicles for resistance-related factors, thereby promoting antibiotic tolerance in susceptible bacteria.

Update on the roles and applications of extracellular vesicles in depression

Depression is a prevalent mental disorder that affects numerous individuals, manifesting as persistent anhedonia, sadness, and hopelessness. Despite extensive research, the exact causes and optimal treatment approaches for depression remain unclear. Extracellular vesicles (EVs), which carry biological molecules such as proteins, lipids, nucleic acids, and metabolites, have emerged as crucial players in both pathological and physiological processes. EVs derived from various sources exert distinct effects on depression. Specifically, EVs released by neurons, astrocytes, microglia, oligodendrocytes, immune cells, stem cells, and even bacteria contribute to the pathogenesis of depression. Moreover, there is growing interest in potential of EVs as diagnostic and therapeutic tools for depression. This review provides a comprehensive overview of recent research on EVs from different sources, their roles in depression, and their potential clinical applications.

The role of the microbiome in head and neck squamous cell cancers

The human microbiome has garnered tremendous interest in the field of oncology, and microbiota studies in head and neck oncology has also flourished. Given the increasing incidence and mortality of HNSCC, as well as the suboptimal outcomes of available treatments, there is an urgent need for innovative approaches involving the microbiome. This review evaluates the intricate relationship between the microbiome and HNSCC, highlighting the potential of the microbiome as a marker for cancer detection, its role in malignancy, and its impact on the efficacy of conventional treatments like chemotherapy and radiotherapy. The review also explores the effects of treatment modalities on the microbiome and discusses the potential of microbiome alterations to predict and influence treatment toxicities such as mucositis and xerostomia. Further research is warranted to characterize the microbiome-HNSCC association, which holds promise for advancing early diagnosis, enhancing prognostic accuracy, and personalizing treatment strategies to improve patient outcomes. The exploration of the microbiome in clinical trials indicates a burgeoning subject of microbiome-focused therapies, heralding a new frontier in most cancer care.

Review on bacterial outer membrane vesicles: structure, vesicle formation, separation and biotechnological applications

Outer membrane vesicles (OMVs), shed by Gram-negative bacteria, are spherical nanostructures that play a pivotal role in bacterial communication and host-pathogen interactions. Comprising an outer membrane envelope and encapsulating a variety of bioactive molecules from their progenitor bacteria, OMVs facilitate material and informational exchange. This review delves into the recent advancements in OMV research, providing a comprehensive overview of their structure, biogenesis, and mechanisms of vesicle formation. It also explores their role in pathogenicity and the techniques for their enrichment and isolation. Furthermore, the review highlights the burgeoning applications of OMVs in the field of biomedicine, emphasizing their potential as diagnostic tools, vaccine candidates, and drug delivery vectors.

Engineered Therapeutic Bacteria with High-Yield Membrane Vesicle Production Inspired by Eukaryotic Membrane Curvature for Treating Inflammatory Bowel Disease

Bacterial membrane vesicles (BMVs) are emerging as powerful natural nanoparticles with transformative potential in medicine and industry. Despite their promise, scaling up BMV production and ensuring stable isolation and storage remain formidable challenges that limit their broader application. Inspired by eukaryotic mechanisms of membrane curvature, we engineered Escherichia coli DH5α to serve as a high-efficiency BMV factory. By fusing the ethanolamine utilization microcompartment shell protein EutS with the outer membrane via the ompA signal peptide, we induced dramatic membrane curvatures that drove enhanced vesiculation. Simultaneously, overexpression of fatty acyl reductase led to the production of amphiphilic fatty alcohols, further amplifying the BMV yield. Dynamic modulation of peptidoglycan hydrolase (PGase) expression facilitated efficient BMV release, resulting in a striking 149.11-fold increase in vesicle production. Notably, the high-yield BMVs from our engineered strain, without the need for purification, significantly bolstered innate immune responses and demonstrated therapeutic efficacy in treating inflammatory bowel disease (IBD). This study presents a strategy to overcome BMV production barriers, showcasing the therapeutic potential of engineered bacteria and BMVs for IBD treatment, while highlighting their potential applications in diverse biomedical fields.

The two coin sides of bacterial extracellular membrane nanovesicles: atherosclerosis trigger or remedy

Among the numerous driving forces that cause the atherosclerotic cardiovascular disease (ASCVD), pathogenic bacterial extracellular membrane nanovesicles (BEMNs) containing toxins and virulence factors appear to be the key trigger of inflammation and atherogenesis, the major processes involved in the pathogenesis of ASCVD. Since BEMNs are the carriers of nanosized biomolecules to distant sites, they are now being considered as a novel drug delivery system. Nowadays, many therapeutic strategies are used to treat ASCVD. However, the conventional anti-atherosclerotic therapies are not effective enough. This primarily due to the inefficiency of non-targeted drug delivery systems to tissue affected areas, which, in turn, leads to numerous side effects, as well as faulty pharmacokinetics. In this regard, nanomedicine methods using nanoparticles (NPs) as targeted drug delivery vehicles proved to be extremely useful. Bioengineered BEMNs equipped with disease-specific ligand moieties and loaded with corresponding drugs represent a promising tool in nanomedicine, which can be used as a novel drug delivery system for a successful therapy of ASCVD. In this review, we outline the involvement of pathogenic BEMNs in the triggering of ASCVD, the conventional therapeutic strategies for the treatment of ASCVD, and the recent trends in nanomedicine using BEMNs and NPs as a vehicle for targeted drug delivery.

Polybacterial Intracellular Macromolecules Shape Single-Cell Epikine Profiles in Upper Airway Mucosa

The upper airway, particularly the nasal and oral mucosal epithelium, serves as a primary barrier for microbial interactions throughout life. Specialized niches like the anterior nares and the tooth are especially susceptible to dysbiosis and chronic inflammatory diseases. To investigate host-microbial interactions in mucosal epithelial cell types, we reanalyzed our single-cell RNA sequencing atlas of human oral mucosa, identifying polybacterial signatures (20% Gram-positive, 80% Gram-negative) within both epithelial- and stromal-resident cells. This analysis revealed unique responses of bacterial-associated epithelia when compared to two inflammatory disease states of mucosa. Single-cell RNA sequencing, in situ hybridization, and immunohistochemistry detected numerous persistent macromolecules from Gram-positive and Gram-negative bacteria within human oral keratinocytes (HOKs), including bacterial rRNA, mRNA and glycolipids. Epithelial cells with higher concentrations of 16S rRNA and glycolipids exhibited enhanced receptor-ligand signaling in vivo. HOKs with a spectrum of polybacterial intracellular macromolecular (PIM) concentrations were challenged with purified exogenous lipopolysaccharide, resulting in the synergistic upregulation of select innate (CXCL8, TNFSF15) and adaptive (CXCL17, CCL28) epikines. Notably, endogenous lipoteichoic acid, rather than lipopolysaccharide, directly correlated with epikine expression in vitro and in vivo. Application of the Drug2Cell algorithm to health and inflammatory disease data suggested altered drug efficacy predictions based on PIM detection. Our findings demonstrate that PIMs persist within mucosal epithelial cells at variable concentrations, linearly driving single-cell effector cytokine expression and influencing drug responses, underscoring the importance of understanding host-microbe interactions and the implications of PIMs on cell behavior in health and disease at single-cell resolution.

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.

From gut to bone: deciphering the impact of gut microbiota on osteoporosis pathogenesis and management

Osteoporosis (OP) is characterized by decreased bone mineral density (BMD) and increased fracture risk, poses a significant global health burden. Recent research has shed light on the bidirectional relationship between gut microbiota (GM) and bone health, presenting a novel avenue for understanding OP pathogenesis and developing targeted therapeutic interventions. This review provides a comprehensive overview of the GM-bone axis, exploring the impact of GM on OP development and management. We elucidate established risk factors and pathogenesis of OP, delve into the diversity and functional changes of GM in OP. Furthermore, we examine experimental evidence and clinical observations linking alterations in GM composition or function with variations in BMD and fracture risk. Mechanistic insights into microbial mediators of bone health, such as microbial metabolites and products, are discussed. Therapeutic implications, including GM-targeted interventions and dietary strategies, are also explored. Finally, we identify future research directions and challenges in translating these findings into clinical practice.

Studies on the Comparative Response of Fibers Obtained from the Pastazzo of Citrus bergamia and Cladodes of Opuntia ficus-indica on In Vitro Model of Neuroinflammation

Adhering to a healthy diet has a protective effect on human health, including a decrease in inflammatory diseases due to consuming fiber. The purpose of this manuscript was to obtain and compare two extracts based on fiber (BF and IF-C), derived from two plants particularly present in the Mediterranean region: bergamot (Citrus bergamia) and prickly pear (Opuntia ficus-indica). The parts used by these plants have been the "pastazzo" for the bergamot and the cladodes for the prickly pear. In addition to in vitro evaluations, the antioxidant activity was also measured on human neurons under inflammatory conditions. Furthermore, the extracts of interest were examined for their effects on the cell cycle and the regulation of pro-apoptotic proteins, caspase 9 and 3, induced by LPS. The results indicated that both extracts had a protective effect against LPS-induced damage, with BF consistently exhibiting superior functionality compared to IF-C. Moreover, the extracts can reduce inflammation, which is a common process of disease. By exploring this avenue, studying the consumption of dietary fiber could enhance our understanding of its positive effects, but additional experiments are needed to confirm this.

Bacteria extracellular vesicle as nanopharmaceuticals for versatile biomedical potential

Bacteria extracellular vesicles (BEVs), characterized as the lipid bilayer membrane-surrounded nanoparticles filled with molecular cargo from parent cells, play fundamental roles in the bacteria growth and pathogenesis, as well as facilitating essential interaction between bacteria and host systems. Notably, benefiting from their unique biological functions, BEVs hold great promise as novel nanopharmaceuticals for diverse biomedical potential, attracting significant interest from both industry and academia. Typically, BEVs are evaluated as promising drug delivery platforms, on account of their intrinsic cell-targeting capability, ease of versatile cargo engineering, and capability to penetrate physiological barriers. Moreover, attributing to considerable intrinsic immunogenicity, BEVs are able to interact with the host immune system to boost immunotherapy as the novel nanovaccine against a wide range of diseases. Towards these significant directions, in this review, we elucidate the nature of BEVs and their role in activating host immune response for a better understanding of BEV-based nanopharmaceuticals' development. Additionally, we also systematically summarize recent advances in BEVs for achieving the target delivery of genetic material, therapeutic agents, and functional materials. Furthermore, vaccination strategies using BEVs are carefully covered, illustrating their flexible therapeutic potential in combating bacterial infections, viral infections, and cancer. Finally, the current hurdles and further outlook of these BEV-based nanopharmaceuticals will also be provided.

Bacteroidetes promotes esophageal squamous carcinoma invasion and metastasis through LPS-mediated TLR4/Myd88/NF-κB pathway and inflammatory changes

Gut microbiota plays a crucial role in gastrointestinal tumors. Additionally, gut microbes influence the progression of esophageal cancer. However, the major bacterial genera that affect the invasion and metastasis of esophageal cancer remain unknown, and the underlying mechanisms remain unclear. Here, we investigated the gut flora and metabolites of patients with esophageal squamous cell carcinoma and found abundant Bacteroides and increased secretion and entry of the surface antigen lipopolysaccharide (LPS) into the blood, causing inflammatory changes in the body. We confirmed these results in a mouse model of 4NQO-induced esophageal carcinoma in situ and further identified epithelial-mesenchymal transition (EMT) occurrence and TLR4/Myd88/NF-κB pathway activation in mouse esophageal tumors. Additionally, in vitro experiments revealed that LPS from Bacteroides fragile promoted esophageal cancer cell proliferation, migration, and invasion, and induced EMT by activating the TLR4/Myd88/NF-κB pathway. These results reveal that Bacteroides are closely associated with esophageal cancer progression through a higher inflammatory response level and signaling pathway activation that are both common to inflammation and tumors induced by LPS, providing a new biological target for esophageal cancer prevention or treatment.

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.

Protective potential of outer membrane vesicles derived from a virulent strain of Francisella tularensis

Francisella tularensis secretes tubular outer membrane vesicles (OMVs) that contain a number of immunoreactive proteins as well as virulence factors. We have reported previously that isolated Francisella OMVs enter macrophages, cumulate inside, and induce a strong pro-inflammatory response. In the current article, we present that OMVs treatment of macrophages also enhances phagocytosis of the bacteria and suppresses their intracellular replication. On the other hand, the subsequent infection with Francisella is able to revert to some extent the strong pro-inflammatory effect induced by OMVs in macrophages. Being derived from the bacterial surface, isolated OMVs may be considered a "non-viable mixture of Francisella antigens" and as such, they present a promising protective material. Immunization of mice with OMVs isolated from a virulent F. tularensis subsp. holarctica strain FSC200 prolonged the survival time but did not fully protect against the infection with a lethal dose of the parent strain. However, the sera of the immunized animals revealed unambiguous cytokine and antibody responses and proved to recognize a set of well-known Francisella immunoreactive proteins. For these reasons, Francisella OMVs present an interesting material for future protective studies.

Edible Plant-Derived Extracellular Vesicles for Oral mRNA Vaccine Delivery

Nucleic acid delivery through extracellular vesicles (EVs) is a well-preserved evolutionary mechanism in all life kingdoms including eukaryotes, prokaryotes, and plants. EVs naturally allow horizontal transfer of native as well as exogenous functional mRNAs, which once incorporated in EVs are protected from enzymatic degradation. This observation has prompted researchers to investigate whether EVs from different sources, including plants, could be used for vaccine delivery. Several studies using human or bacterial EVs expressing mRNA or recombinant SARS-CoV-2 proteins showed induction of a humoral and cell mediated immune response. Moreover, EV-based vaccines presenting the natural configuration of viral antigens have demonstrated advantages in conferring long-lasting immunization and lower toxicity than synthetic nanoparticles. Edible plant-derived EVs were shown to be an alternative to human EVs for vaccine delivery, especially via oral administration. EVs obtained from orange juice (oEVs) loaded with SARS-CoV-2 mRNAs protected their cargo from enzymatic degradation, were stable at room temperature for one year, and were able to trigger a SARS-CoV-2 immune response in mice. Lyophilized oEVs containing the S1 mRNA administered to rats via gavage induced a specific humoral immune response with generation of blocking antibodies, including IgA and Th1 lymphocyte activation. In conclusion, mRNA-containing oEVs could be used for developing new oral vaccines due to optimal mucosal absorption, resistance to stress conditions, and ability to stimulate a humoral and cellular immune response.

Role of Extracellular Vesicles in Immunity and Host Defense

Extracellular vesicles (EVs) are membrane-bound structures released by cells and have become significant players in immune system functioning, primarily by facilitating cell-to-cell communication. Immune cells like neutrophils and dendritic cells release EVs containing bioactive molecules that modulate chemotaxis, activate immune cells, and induce inflammation. EVs also contribute to antigen presentation, lymphocyte activation, and immune tolerance. Moreover, EVs play pivotal roles in antimicrobial host defense. They deliver microbial antigens to antigen-presenting cells (APCs), triggering immune responses, or act as decoys to neutralize virulence factors and toxins. This review discusses host and microbial EVs' multifaceted roles in innate and adaptive immunity, highlighting their involvement in immune cell development, antigen presentation, and antimicrobial responses.

Bacterial Outer Membrane Vesicles: Role in Pathogenesis and Host-Cell Interactions

Outer membrane vesicles (OMVs) are small, spherical structures released from the outer membranes of Gram-negative bacteria into the surrounding environment. Investigations into OMVs range from their biogenesis and cargo composition to their ability to transfer virulence factors and modulate host immune responses. This emerging understanding of OMVs has unveiled their pivotal role in the pathogenicity of infectious diseases, shedding light on their interactions with host cells, their contributions to inflammation, their potential involvement in antimicrobial resistance, and their promising use for the development of novel treatments and therapies. Numerous studies have associated the OMVs of pathogenic bacteria with the exacerbation of inflammatory diseases, underlining the significance of understanding the mechanisms associated with these vesicles to find alternatives for combating these conditions. Additionally, OMVs possess the ability to act as decoys, absorbing and neutralizing antibiotics, which significantly diminishes the efficacy of a broad spectrum of antimicrobial agents. Another subtopic of interest is OMVs produced by commensal microbiota. These vesicles are increasingly acknowledged for their mutualistic functions, significantly influencing their host's physiology and immune responses. Consequently, OMVs play a crucial role in maintaining a balanced gut microbiota by fostering symbiotic relationships that significantly contribute to the overall health and well-being of the host. This comprehensive review aims to provide an up-to-date review of OMVs derived from Gram-negative bacteria, summarizing current research findings, and elucidating the multifaceted role of these vesicles in diverse biological contexts.

Both extracellular vesicles from helicobacter pylori-infected cells and helicobacter pylori outer membrane vesicles are involved in gastric/extragastric diseases

Bacterial-derived extracellular vesicles (EVs) have emerged as crucial mediators in the cross-talk between hosts and pathogens, playing a significant role in infectious diseases and cancers. Among these pathogens, Helicobacter pylori (H. pylori) is a particularly important bacterium implicated in various gastrointestinal disorders, gastric cancers, and systemic illnesses. H. pylori achieves these effects by stimulating host cells to secrete EVs and generating internal outer membrane vesicles (OMVs). The EVs derived from H. pylori-infected host cells modulate inflammatory signaling pathways, thereby affecting cell proliferation, apoptosis, cytokine release, immune cell modification, and endothelial dysfunction, as well as disrupting cellular junctional structures and inducing cytoskeletal reorganization. In addition, OMVs isolated from H. pylori play a pivotal role in shaping subsequent immunopathological responses. These vesicles incite both inflammatory and immunosuppressive reactions within the host environment, facilitating pathogen evasion of host defenses and invasion of host cells. Despite this growing understanding, research involving H. pylori-derived EVs remains in its early stages across different domains. In this comprehensive review, we present recent advancements elucidating the contributions of EV components, such as non-coding RNAs (ncRNAs) and proteins, to the pathogenesis of gastric and extragastric diseases. Furthermore, we highlight their potential utility as biomarkers, therapeutic targets, and vehicles for targeted delivery.

Bacterial Outer Membrane Vesicles and Immune Modulation of the Host

This article reviews the role of outer membrane vesicles (OMVs) in mediating the interaction between Gram-negative bacteria and their human hosts. OMVs are produced by a diverse range of Gram-negative bacteria during infection and play a critical role in facilitating host-pathogen interactions without requiring direct cell-to-cell contact. This article describes the mechanisms by which OMVs are formed and subsequently interact with host cells, leading to the transport of microbial protein virulence factors and short interfering RNAs (sRNA) to their host targets, exerting their immunomodulatory effects by targeting specific host signaling pathways. Specifically, this review highlights mechanisms by which OMVs facilitate chronic infection through epigenetic modification of the host immune response. Finally, this review identifies critical knowledge gaps in the field and offers potential avenues for future OMV research, specifically regarding rigor and reproducibility in OMV isolation and characterization methods.