Extracellular vesicles derived from Porphyromonas gingivalis induce trigeminal nerve-mediated cognitive impairment

Bacterial extracellular vesicles in the initiation, progression and treatment of atherosclerosis

Atherosclerosis is the primary cause of cardiovascular and cerebrovascular diseases. However, current anti-atherosclerosis drugs have shown conflicting therapeutic outcomes, thereby spurring the search for novel and effective treatments. Recent research indicates the crucial involvement of oral and gastrointestinal microbiota in atherosclerosis. While gut microbiota metabolites, such as choline derivatives, have been extensively studied and reviewed, emerging evidence suggests that bacterial extracellular vesicles (BEVs), which are membrane-derived lipid bilayers secreted by bacteria, also play a significant role in this process. However, the role of BEVs in host-microbiota interactions remains insufficiently explored. This review aims to elucidate the complex communication mediated by BEVs along the gut-heart axis. In this review, we summarize current knowledge on BEVs, with a specific focus on how pathogen-derived BEVs contribute to the promotion of atherosclerosis, as well as how BEVs from gut symbionts and probiotics may mitigate its progression. We also explore the potential and challenges associated with engineered BEVs in the prevention and treatment of atherosclerosis. Finally, we discuss the benefits and challenges of using BEVs in atherosclerosis diagnosis and treatment, and propose future research directions to address these issues.

Advanced biomaterials for targeting mature biofilms in periodontitis therapy

Periodontitis is a chronic inflammatory disease primarily caused by bacteria, leading to inflamed and bleeding gums, periodontal pocket formation, and bone loss. Affecting 70%-90% of adults over 65, periodontitis is a leading cause of tooth loss and significantly impacts quality of life. Standard treatments, including subgingival scraping and antibiotics, have limitations, and antibiotic resistance among periodontal pathogens is an increasing concern. Biofilms are barriers to drugs and immune responses, contributing to bacterial resistance and reducing antibiotic effectiveness. Due to their adjustable physicochemical properties, bioactive materials potentially eliminate bacterial biofilms, presenting a promising alternative for periodontitis therapy. In this review, the recent innovations in biomaterials for removing mature biofilms in periodontitis are examined, and their broader potential is discussed. Additionally, the compositions of bacterial biofilms, formation pathways, and intrinsic drug resistance mechanisms are discussed. Finally, the strategies for optimizing subgingival biofilm removal in periodontitis are highlighted, such as targeting biofilms-embedded bacteria, disrupting the extracellular polymeric substances, and utilizing combined approaches. A comprehensive understanding of the properties of biomaterials guides the rational design of highly targeted and effective therapies for periodontitis.

Porphyromonas gingivalis outer membrane vesicles augments proliferation and metastasis of oral squamous cell carcinoma cells

BACKGROUND

Porphyromonas gingivalis (P. gingivalis) is closely related to Oral squamous cell carcinoma (OSCC), and P. gingivalis outer membrane vesicles (OMVs) is the main pathogenic factor, which is associated with periodontitis, atherosclerosis and other diseases. However, few studies have reported an association between P. gingivalis OMVs and OSCC. The purpose of this study was to establish the clinical relationship between P. gingivalis and OSCC based on clinical samples. Further, the effect of P. gingivalis OMVs on OSCC was observed with cell model in vitro, and the possible molecular mechanism was discussed.

METHODS

Immunohistochemistry was used to detect the abundance of P. gingivalis in OSCC and its paired paracancer tissues, and to analyze the correlation between P. gingivalis and clinicopathological parameters of patients. P. gingivalis OMVs were isolated to observe its effects on the proliferation and migration of OSCC cell lines. RNA-seq was performed and the expression of differentially expressed genes (DEGs) was detected by real-time quantitative PCR (RT-qPCR) to explore the potential mechnism of P. gingivalis OMVs on OSCC progression.

RESULTS

The abundance of P. gingivalis in OSCC was higher than that in para-cancerous tissues, and was positively correlated with the degree of tissue differentiation (P = 0.028), T stage (P < 0.001), and clinical stage (P = 0.011). P. gingivalis OMVs promoted the proliferation and migration of HN6 cells, and promoted the proliferation of CAL27 cells, but had no significant effect on its migration. P. gingivalis OMVs treatment attenuated the expressions of TNFSF15, ZNF292, ATRX, ASPM and KIF20B in CAL27 and HN6 cells.

CONCLUSION

This study suggests that P. gingivalis may be an indicator of poor prognosis for OSCC. P. gingivalis OMVs may down-regulate the expression of TNFSF15, ZNF292, ATRX, ASPM, KIF20B and participate in the occurrence and development of OSCC.

Chronic sleep deprivation promotes experimental autoimmune uveitis through STAT1 phosphorylation, ISG15 expression and enhanced pathogenicity of macrophages

Chronic sleep deprivation (CSD) is increasingly common in modern society and is linked to various diseases, including autoimmune conditions like experimental autoimmune uveitis (EAU), a severe ocular inflammation. The pathogenesis of EAU remains unclear, but poor sleep quality has been shown to exacerbate inflammation through immune modulation. To explore this relationship, we conducted a clinical study at the Ophthalmology Center of Renmin Hospital of Wuhan University (July 2023-July 2024), assessing sleep quality in uveitis patients using the Pittsburgh Sleep Quality Index (PSQI). Based on PSQI scores, patients were categorized into four groups, and their symptoms and characteristics were recorded. Simultaneously, a B10.RIII mouse model of CSD and EAU was developed. Western blotting assessed the phosphorylation of Signal Transducer and Activator of Transcription 1 (STAT1) and the expression of Interferon-Stimulated Gene 15 (ISG15) expression, while immunofluorescence and western blotting evaluated macrophage activity and cytokine secretion. Clinical results showed a strong correlation between poor sleep quality and worsened inflammatory symptoms. In mice, CSD increased STAT1 phosphorylation and ISG15 expression, enhancing macrophage activity and worsening ocular inflammation. Our findings suggest that CSD exacerbates EAU through STAT1 phosphorylation, ISG15 expression, and macrophage activation. The clinical data further support this mechanism, indicating that improving sleep quality could reduce the risk of autoimmune diseases and offering new insights into the connection between sleep and immune function.

Collagenase Degradable Biomimetic Nanocages Attenuate Porphyromonas gingivalis Mediated Neurocognitive Dysfunction via Targeted Intracerebral Antimicrobial Photothermal and Gas Therapy

Porphyromonas gingivalis (P.g.), a pathogen linked to periodontitis, is reported to be associated with severe neurocognitive dysfunction. However, there are few reports focusing on improving neurological function in the brain by eliminating P.g.. Therefore, we developed a core-shell nanocomposite for targeted intracerebral P.g. clearance and ameliorating neurocognitive impairments, Pt-Au@C-P.g.-MM, consisting of platinum nanoparticles (Pt NPs) encapsulated within Au nanocages (Pt-Au) as the core and a shell made of collagen and macrophage membranes from macrophage pretreated with P.g. (C-P.g.-MM). This design enhanced the nanocomposite's ability to cross the blood-brain barrier (BBB) and specifically target intracerebral P.g. through coating of P.g.-MM. Pt-Au@C-P.g.-MM depended on collagen to neutralize excessive collagenase from P.g., promoting its directed migration toward P.g.. Au nanocages exhibited excellent photothermal effects under near-infrared (NIR) laser irradiation, while Pt NPs also provided an efficient antibacterial gas therapy by generating oxygen to expose anaerobic P.g.. As a result, Pt-Au@C-P.g.-MM contributed to a synergistic antibacterial therapy and significantly reduced P.g. mediated neurocognitive dysfunction in periodontitis mice induced by oral P.g. infection. Based on the insights provided by the transcriptome sequencing analysis, anti-P.g. activity of Pt-Au@C-P.g.-MM facilitated the transition of microglia from the M1 to M2 phenotype by stimulating the PI3K-Akt pathway and reducing neuronal damage through the Wnt/β-catenin pathway.

The Vaginally Exposed Extracellular Vesicle of Gardnerella vaginalis Induces RANK/RANKL-Involved Systemic Inflammation in Mice

Gardnerella vaginalis (GV), an opportunistic pathogen excessively proliferated in vaginal dysbiosis, causes systemic inflammation including vaginitis, neuroinflammation, and osteitis. To understand its systemic inflammation-triggering factor, we purified extracellular vesicles isolated from GV (gEVs) and examined their effect on the occurrence of vaginitis, osteitis, and neuroinflammation in mice with and without ovariectomy (Ov). The gEVs consisted of lipopolysaccharide, proteins, and nucleic acid and induced TNF-α and RANKL expression in macrophage cells. When the gEVs were vaginally exposed in mice without Ov, they significantly induced RANK, RANKL, and TNF-α expression and NF-κB+ cell numbers in the vagina, femur, hypothalamus, and hippocampus, as observed in GV infection. The gEVs decreased time spent in the open field (OT) in the elevated plus maze test by 47.3%, as well as the distance traveled in the central area (DC) by 28.6%. In the open field test, they also decreased the time spent in the central area (TC) by 39.3%. Additionally, gEVs decreased spontaneous alteration (SA) in the Y-maze test by 33.8% and the recognition index (RI) in the novel object recognition test by 26.5%, while increasing the immobility time (IT) in the tail suspension test by 36.7%. In mice with OV (Ov), the gEVs also induced RANK, RANKL, and TNF-α expression and increased NF-κB+ cell numbers in the vagina, femur, hypothalamus, and hippocampus compared to vehicle-treated mice. When gEVs were exposed to mice with Ov, gEVs also reduced the DC, TC, OT, SA, and RI to 62.1%, 62.7%, 28.2%, 90.7%, and 85.4% of mice with Ov, respectively, and increased IT to 122.9% of mice with Ov. Vaginally exposed fluorescein-isothiocyanate-tagged gEVs were detected in the blood, femur, and hippocampus. These findings indicate that GV-derived gEVs may induce systemic inflammation through the activation of RANK/RANKL-involved NF-κB signaling, leading to systemic disorders including vaginitis, osteoporosis, depression, and cognitive impairment. Therefore, gEVs may be an important risk factor for vaginitis, osteoporosis, depression, and cognitive impairment in women.

[Prevotella nigrescens exacerbates periodontal inflammation and impairs cognitive function in mice]

OBJECTIVES

To investigate the effects of periodontitis induced by Prevotella nigrescens (Pn) combined with ligation on cognitive functions in mice.

METHODS

Twenty-four C57BL/6J mice were randomly divided into control group, ligation group, and ligation + Pn treatment (P+Pn) group. Experimental periodontitis was induced by silk ligation of the first molars followed by topical application of Pn for 6 weeks. After modeling, alveolar bone resorption was assessed using micro-CT and histological analysis. Learning and memory abilities of the mice were evaluated using open field test (OFT), novel object recognition test (NORT), and Morris water maze test (MWM). Seven weeks after the start of modeling, the mice were sacrificed for examining histopathological changes in the hippocampus using HE and Nissl staining.

RESULTS

After 6 weeks of molar ligation, micro-CT revealed horizontal alveolar bone resorption and furcation exposure in the mice, and histological analysis showed apical migration of the junctional epithelium, epithelial ridge hyperplasia, and lymphocyte infiltration, and these changes were obviously worsened in P+Pn group. Alveolar bone height decreased significantly in both ligation groups compared to the control group. Cognitive tests showed that the mice in both of the ligation groups traveled shorter distances in OFT, showed reduced novel object preference in NORT, and exhibited longer escape latencies in MWM, and the mice in P+Pn group had significantly poorer performances in the tests. Histologically, obvious neuronal cytoplasmic degeneration, necrosis, nuclear pyknosis, vacuolation, and reduced Nissl bodies and viable neurons were observed in the hippocampal regions of the mice in the two ligation groups.

CONCLUSIONS

Pn infection aggravates alveolar bone destruction, accelerates necrosis and causes morphological abnormalities of neuronal cells in the hippocampus to reduce cognitive functions of mice with periodontitis.

Critical roles of extracellular vesicles in periodontal disease and regeneration

Extracellular vesicles (EVs) are evolutionarily conserved communication mediators that play key roles in the development of periodontal disease as well as in regeneration processes. This concise review first outlines the pathogenic mechanisms through which EVs derived from bacteria lead to the progression of periodontitis, with a focus on the enrichment of virulence factors, the amplification of immune responses, and the induction of bone destruction as key aspects influenced by bacterial EVs. This review aims to elucidate the positive effects of EVs derived from mesenchymal stem cells (MSC-EVs) on periodontal tissue regeneration. In particular, the anti-inflammatory properties of MSC-EVs and their impact on the intricate interplay between MSCs and various immune cells, including macrophages, dendritic cells, and T cells, are described. Moreover, recent advancements regarding the repair-promoting functions of MSC-EVs are detailed, highlighting the mechanisms underlying their ability to promote osteogenesis, cementogenesis, angiogenesis, and the homing of stem cells, thus contributing significantly to periodontal tissue regeneration. Furthermore, this review provides insights into the therapeutic efficacy of MSC-EVs in treating periodontitis within a clinical context. By summarizing the current knowledge, this review aims to provide a comprehensive understanding of how MSC-EVs can be harnessed for the treatment of periodontal diseases. Finally, a discussion is presented on the challenges that lie ahead and the potential practical implications for translating EV-based therapies into clinical practices for the treatment of periodontitis.

Porphyromonas gingivalis: a potential trigger of neurodegenerative disease

Porphyromonas gingivalis (P. gingivalis) is a gram-negative bacterium and the main causative agent of periodontitis, a disease closely associated with the development of periodontal disease. The progression of periodontitis, a chronic infectious disease, is intricately linked to the inflammatory immune response. Inflammatory cytokines act on periodontal tissues via immunomodulation, resulting in the destruction of the periodontal tissue. Recent studies have established connections between periodontitis and various systemic diseases, including cardiovascular diseases, tumors, and neurodegenerative diseases. Neurodegenerative diseases are neurological disorders caused by immune system dysfunction, including Alzheimer's and Parkinson's diseases. One of the main characteristics of neurodegenerative diseases is an impaired inflammatory response, which mediates neuroinflammation through microglial activation. Some studies have shown an association between periodontitis and neurodegenerative diseases, with P. gingivalis as the primary culprit. P. gingivalis can cross the blood-brain barrier (BBB) or mediate neuroinflammation and injury through a variety of pathways, including the gut-brain axis, thereby affecting neuronal growth and survival and participating in the onset and progression of neurodegenerative diseases. However, comprehensive and systematic summaries of studies on the infectious origin of neurodegenerative diseases are lacking. This article reviews and summarizes the relationship between P. gingivalis and neurodegenerative diseases and its possible regulatory mechanisms. This review offers new perspectives into the understanding of neurodegenerative disease development and highlights innovative approaches for investigating and developing tailored medications for treating neurodegenerative conditions, particularly from the viewpoint of their association with P. gingivalis.

Porphyromonas gingivalis and Its Outer Membrane Vesicles Induce Neuroinflammation in Mice Through Distinct Mechanisms

BACKGROUND

Alzheimer's disease (AD) is the most common chronic neurodegenerative disorder, with neuroinflammation playing an important role in its progression to become a major research focus. The role of Porphyromonas gingivalis (Pg) and its outer membrane vesicles (Pg OMVs) in AD development is uncertain, particularly regarding their effects on neuroinflammation.

METHODS

The cognition of mice injected with Pg, Pg OMVs, or PBS via the tail vein was assessed by the Morris water maze test. Pathological changes in the mouse brain were analyzed via immunohistochemistry, immunofluorescence and hematoxylin‒eosin (H&E) staining, and the ultrastructure of the hippocampus was observed via transmission electron microscopy (TEM). Plasma levels of inflammatory factors were assessed by enzyme-linked immunosorbent assay (ELISA). Protein levels of brain inflammatory factor, occludin, and NLRP3 inflammasome-related proteins were assessed by western blotting.

RESULTS

Memory impairment; notable neuroinflammation, including astrocyte and microglial activation; and elevated protein levels of IL-1β, TNF-α, and IL-6 in the hippocampus were detected in the Pg and Pg OMV groups. However, Pg induced weight loss and systemic inflammation, such as splenomegaly and increased IL-1β and TNF-α levels in plasma, whereas Pg OMVs had minimal impact. In addition, Pg induced more pronounced activation of the NLRP3 inflammasome compared to Pg OMVs. In contrast, only the Pg OMV group exhibited blood-brain barrier (BBB) disruption characterized by reduced integrity of tight junctions and lower levels of occludin protein.

CONCLUSIONS

Pg is associated with a significant immune response and systemic inflammation, which in turn exacerbates neuroinflammation via activating NLRP3 inflammasome. However, Pg OMVs might elude the systemic immune response and disrupt tight junctions, thereby entering the brain and directly triggering neuroinflammation.

Exploring the Link Between Periodontitis and Alzheimer's Disease-Could a Nanoparticulate Vaccine Break It?

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, as approximately 55 million people worldwide are affected, with a significant tendency to increase. It reveals three main pathological features: amyloid plaques, neurofibrillary tangles, and neuroinflammation, responsible for the neurodegenerative changes that slowly lead to deterioration of personality and cognitive control. Over a century after the first case report, effective treatments remain elusive, likely due to an incomplete understanding of the precise mechanisms driving its pathogenesis. Recent studies provide growing evidence of an infectious aetiology for AD, a hypothesis reinforced by findings that amyloid beta functions as an antimicrobial peptide. Among the microorganisms already associated with AD, Porphyromonas gingivalis (Pg), the keystone pathogen of periodontitis (PeD), has received particular attention as a possible aetiological agent for AD development. Herein, we review the epidemiological and genetic evidence linking PeD and Pg to AD, highlighting the identification of periodontal bacteria in post mortem analysis of AD patients' brains and identifying putative mechanistic links relevant to the biological plausibility of the association. With the focus on AD research shifting from cure to prevention, the proposed mechanisms linking PeD to AD open the door for unravelling new prophylactic approaches able to reduce the global burden of AD. As hypothesised in this review, these could include a bionanotechnological approach involving the development of an oral nanoparticulate vaccine based on Pg-specific antigens. Such a vaccine could prevent Pg antigens from progressing to the brain and triggering AD pathology, representing a promising step toward innovative and effective AD prevention.

Alzheimer's Disease and Porphyromonas gingivalis: Exploring the Links

Recent research highlights compelling links between oral health, particularly periodontitis, and systemic diseases, including Alzheimer's disease (AD). Although the biological mechanisms underlying these associations remain unclear, the role of periodontal pathogens, particularly Porphyromonas gingivalis, has garnered significant attention. P. gingivalis, a major driver of periodontitis, is recognized for its potential systemic effects and its putative role in AD pathogenesis. This review examines evidence connecting P. gingivalis to hallmark AD features, such as amyloid β accumulation, tau hyperphosphorylation, neuroinflammation, and other neuropathological features consistent with AD. Virulence factors, such as gingipains and lipopolysaccharides, were shown to be implicated in blood-brain barrier disruption, neuroinflammation, and neuronal damage. P. gingivalis-derived outer membrane vesicles may serve to disseminate virulence factors to brain tissues. Indirect mechanisms, including systemic inflammation triggered by chronic periodontal infections, are also supposed to exacerbate neurodegenerative processes. While the exact pathways remain uncertain, studies detecting P. gingivalis virulence factors and its other components in AD-affected brains support their possible role in disease pathogenesis. This review underscores the need for further investigation into P. gingivalis-mediated mechanisms and their interplay with host responses. Understanding these interactions could provide critical insights into novel strategies for reducing AD risk through periodontal disease management.

Effect of β-1,4-GalTI on the biological function of astrocytes treated by LPS

Inflammation of the central nervous system (CNS) is a common feature of neurological disorders and infections, playing a crucial role in the development of CNS-related conditions. CNS inflammation is primarily regulated by glial cells, with astrocytes being the most abundant type in the mammalian CNS. Numerous studies have demonstrated that astrocytes, as immunocompetent cells, perform diverse and complex functions in both health and disease. Glycosylation, a critical post-translational modification of proteins, regulates numerous biological functions. The expression and activity of glycosyltransferases, the enzymes responsible for glycosylation, are closely associated with the pathogenesis of various diseases. β-1,4-GalTI, a mammalian glycosyltransferase, plays a significant role in cell-cell interactions, adhesion, and migration. Although many studies have focused on β-1,4-GalTI, few have explored its effects on astrocyte function. In this study, we constructed lentiviral vectors for both interference and overexpression of β-1,4-GalTI and discovered that β-1,4-GalTI knockdown inhibited astrocyte migration and proliferation, while its overexpression promoted these processes. Concurrently, β-1,4-GalTI knockdown reduced the expression of TNF-α, IL-1β, and IL-6, whereas overexpression enhanced the expression of these cytokines. These findings suggest that modulating β-1,4-GalTI activity can influence the molecular functions of astrocytes and provide a theoretical foundation for further research into β-1,4-GalTI as a potential therapeutic target in astrocyte-mediated inflammation.

Alleviation of Helicobacter pylori- or aspirin-induced gastritis and neuroinflammation in mice by Lactococcus lactis and Bifidobacterium longum

Helicobacter pylori (HP) causes gastritis and peptic ulcer. Therefore, we examined whether probiotics Lactococcus lactis P135 and Bifidobacterium longum P142, which inhibited HP growth by 37.9% and 35.3%, respectively, and HP-induced IL-8 expression in KATO III cells by 68.6% and 63.1%, respectively, compared to those of normal controls, could mitigate HP-induced gastritis and psychiatric disorder in mice. Oral administration of P135 and/or P142 alleviated HP- or aspirin-induced gastritis, colitis, neuroinflammation, and depression/cognitive impairment-like behavior. They also suppressed HP infection, neutrophil infiltration, and NF-κB activation in the stomach and TNF-α expression and NF-κB activation in the colon and hippocampus. of P135 and/or P142 alleviated HP- or aspirin-induced gut dysbiosis: they decreased Lachnospiracease, Helicobacteriaceae, and Akkermansiaceae populations and increased Bacteroidaceae and Muribaculaceae populations. These findings suggest that HP growth/inflammation-inhibitory P135 and/or P142 may alleviate gut inflammation (gastritis and colitis) and neuroinflammation through the suppression of neutrophil infiltration, NF-κB activation, and HP growth, thereby leading to the attenuation of systemic inflammation and psychiatric disorder.

Extracellular vesicle production by oral bacteria related to dental caries and periodontal disease: role in microbe-host and interspecies interactions

Extracellular vesicles (EVs) are cell membrane-derived structures between 20-400 nm in size. In bacteria, EVs play a crucial role in molecule secretion, cell wall biogenesis, cell-cell communication, biofilm development, and host-pathogen interactions. Despite these increasing reports of bacterial-derived vesicles, there remains a limited number of studies that summarize oral bacterial EVs, their cargo, and their main biological functions. Therefore, the aim of this review is to present the latest research on oral bacteria-derived EVs and how they can modulate various physiological and pathological processes in the oral cavity, including the pathogenesis of highly relevant diseases such as dental caries and periodontitis and their systemic complications. Overall, caries-associated bacteria (such as Streptococcus mutans) as well as periodontal pathogens (including the red complex pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) have all been shown to produce EVs that carry an array of virulent factors and molecules involved in biofilm and immune modulation, bacterial adhesion, and extracellular matrix degradation. As bacterial EV production is strongly impacted by genotypic and environmental variations, the inhibition of EV genesis and secretion remains a key potential future approach against oral diseases.

Intranasal administration of Clostridium butyricum and its derived extracellular vesicles alleviate LPS-induced acute lung injury

Acute lung injury (ALI) is associated with high morbidity and mortality rates. However, its clinical treatment is limited. Currently, the treatment of lung diseases by regulating the lung microbiota has become a research hotspot. In this study, we investigated the protective effects of the intranasal administration of Clostridium butyricum and its derived extracellular vesicles (EVs) against lipopolysaccharide (LPS)-induced ALI. The results demonstrated that compared with the LPS group, the pre-treatment group with C. butyricum and its EVs reduced the expression of pro-inflammatory cytokines and alleviated the symptoms in ALI mice by inhibiting the TLR4/MyD88 signaling pathway. Moreover, C. butyricum and its derived EVs inhibited the expression of apoptosis-related proteins and increased the expression of lung barrier proteins. Additionally, the intervention of C. butyricum changed the composition of the pulmonary microbiota. At the species level, LPS significantly increased the relative abundance of Acinetobacter johnsonii, while C. butyricum reversed this effect. In conclusion, these data demonstrate that intranasal administration of C. butyricum and its EVs can prevent LPS-induced ALI by reducing inflammation, inhibiting apoptosis, and improving lung barrier function. Additionally, C. butyricum regulated the pulmonary microbiota of mice to alleviate LPS-induced ALI.IMPORTANCEThe disorder of pulmonary microbiota plays an important role in the progression of acute lung injury (ALI). However, very few studies have been conducted to treat ALI by modulating pulmonary microbiota. In this study, the diversity and composition of pulmonary microbiota were altered in lipopolysaccharide (LPS)-induced ALI mice, but the ecological balance of the pulmonary microbiota was restored by intranasal administration of Clostridium butyricum. Moreover, the study reported the mechanism of C. butyricum and its derived extracellular vesicles for the treatment of LPS-induced ALI. These results reveal the importance of pulmonary microbiota in ALI disease. It provides a new approach for the treatment of ALI with new-generation probiotics.

Mechanisms of oral microflora in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease with complex pathogenesis and no effective treatment. Recent studies have shown that dysbiosis of the oral microflora is closely related to the development of PD. The abnormally distributed oral microflora of PD patients cause degenerative damage and necrosis of dopamine neurons by releasing their own components and metabolites, intervening in the oral-gut-brain axis, crossing the biofilm, inducing iron dysregulation, activating inter-microflora interactions, and through the mediation of saliva,ultimately influencing the development of the disease. This article reviews the structure of oral microflora in patients with PD, the mechanism of development of PD caused by oral microflora, and the potential value of targeting oral microflora in developing a new strategy for PD prevention, diagnosis and treatment.

The extracellular vesicle of depressive patient-derived Escherichia fergusonii induces vagus nerve-mediated neuroinflammation in mice

BACKGROUND

Gut microbiota dysbiosis is closely associated with psychiatric disorders such as depression and anxiety (DA). In our preliminary study, fecal microbiota transplantation from volunteers with psychological stress and subclinical symptoms of depression (Vsd) induced DA-like behaviors in mice. Escherichia fergusonii (Esf) was found to be more abundant in the feces of Vsd compared to healthy volunteers. Therefore, we investigated the effect of Esf on DA-like behavior and neuroinflammation in mice with and without celiac vagotomy.

METHODS AND RESULTS

Orally gavaged Esf increased DA-like behaviors, tumor necrosis factor (TNF)-α, and toll-like receptor-4 (TLR4) expression, and NF-κB+Iba1+ and lipopolysaccharide (LPS)+Iba1+ cell populations, while decreasing serotonin, 5-HT1A receptor, and brain-derived neurotrophic factor (BDNF) expression in the hippocampus and prefrontal cortex. However, celiac vagotomy attenuated Esf-induced DA-like behavior and neuroinflammation. Orally gavaged extracellular vesicle (EV) from Vsd feces (vfEV) or Esf culture (esEV) induced DA-like behavior and inflammation in hippocampus, prefrontal cortex and colon. However, celiac vagotomy attenuated vfEV- or esEV-induced DA-like behaviors and inflammation in the brain alone, while vfEV- or esEV-induced blood LPS and TNF-α levels, colonic TNF-α expression and NF-κB-positive cell number, and fecal LPS level were not. Although orally gavaged fluorescence isothiocyanate-labeled esEV was translocated into the blood and hippocampus, celiac vagotomy decreased its translocation into the hippocampus alone.

CONCLUSIONS

esEVs may be translocated into the brain via the vagus nerve and bloodstream, subsequently inducing TNF-α expression and suppressing serotonin, its receptor, and BDNF expression through the activation of TLR4-mediated NF-κB signaling, thereby contributing to DA pathogenesis.

Bacterial Membrane Vesicles: The Missing Link Between Bacterial Infection and Alzheimer Disease

Periodontitis is a common chronic inflammatory disease, affecting approximately 19% of the global adult population. A relationship between periodontal disease and Alzheimer disease has long been recognized, and recent evidence has been uncovered to link these 2 diseases mechanistically. Periodontitis is caused by dysbiosis in the subgingival plaque microbiome, with a pronounced shift in the oral microbiota from one consisting primarily of Gram-positive aerobic bacteria to one predominated by Gram-negative anaerobes, such as Porphyromonas gingivalis. A common phenomenon shared by all bacteria is the release of membrane vesicles to facilitate biomolecule delivery across long distances. In particular, the vesicles released by P gingivalis and other oral pathogens have been found to transport bacterial components across the blood-brain barrier, initiating the physiologic changes involved in Alzheimer disease. In this review, we summarize recent data that support the relationship between vesicles secreted by periodontal pathogens to Alzheimer disease pathology.

Microbiota-Derived Extracellular Vesicle as Emerging Actors in Host Interactions

The human microbiota is an intricate micro-ecosystem comprising a diverse range of dynamic microbial populations mainly consisting of bacteria, whose interactions with hosts strongly affect several physiological and pathological processes. The gut microbiota is being increasingly recognized as a critical player in maintaining homeostasis, contributing to the main functions of the intestine and distal organs such as the brain. However, gut dysbiosis, characterized by composition and function alterations of microbiota with intestinal barrier dysfunction has been linked to the development and progression of several pathologies, including intestinal inflammatory diseases, systemic autoimmune diseases, such as rheumatic arthritis, and neurodegenerative diseases, such as Alzheimer's disease. Moreover, oral microbiota research has gained significant interest in recent years due to its potential impact on overall health. Emerging evidence on the role of microbiota-host interactions in health and disease has triggered a marked interest on the functional role of bacterial extracellular vesicles (BEVs) as mediators of inter-kingdom communication. Accumulating evidence reveals that BEVs mediate host interactions by transporting and delivering into host cells effector molecules that modulate host signaling pathways and cell processes, influencing health and disease. This review discusses the critical role of BEVs from the gut, lung, skin and oral cavity in the epithelium, immune system, and CNS interactions.

Effects of bacterial extracellular vesicles derived from oral and gastrointestinal pathogens on systemic diseases

Oral microbiota and gastrointestinal microbiota, the two largest microbiomes in the human body, are closely correlated and frequently interact through the oral-gut axis. Recent research has focused on the roles of these microbiomes in human health and diseases. Under normal conditions, probiotics and commensal bacteria can positively impact health. However, altered physiological states may induce dysbiosis, increasing the risk of pathogen colonization. Studies suggest that oral and gastrointestinal pathogens contribute not only to localized diseases at their respective colonized sites but also to the progression of systemic diseases. However, the mechanisms by which bacteria at these local sites are involved in systemic diseases remain elusive. In response to this gap, the focus has shifted to bacterial extracellular vesicles (BEVs), which act as mediators of communication between the microbiota and the host. Numerous studies have reported the targeted delivery of bacterial pathogenic substances from the oral cavity and the gastrointestinal tract to distant organs via BEVs. These pathogenic components subsequently elicit specific cellular responses in target organs, thereby mediating the progression of systemic diseases. This review aims to elucidate the extensive microbial communication via the oral-gut axis, summarize the types and biogenesis mechanisms of BEVs, and highlight the translocation pathways of oral and gastrointestinal BEVs in vivo, as well as the impacts of pathogens-derived BEVs on systemic diseases.

Sialic acid metabolism of oral bacteria and its potential role in colorectal cancer and Alzheimer's disease

Sialic acid metabolism in oral bacteria is a complex process involving nutrient acquisition, immune evasion, cell surface modification, and the production of metabolites that contribute to bacterial persistence and virulence in the oral cavity. In addition to causing various periodontal diseases, certain oral pathogenic bacteria, such as Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum, can induce inflammatory reactions and influence the immunity of host cells. These associations with host cells are linked to various diseases, particularly colorectal cancer and Alzheimer's disease. Sialic acid can be found in the host oral mucosa, saliva, or food residues in the oral cavity, and it may promote the colonization of oral bacteria and contribute to disease development. This review aims to summarize the role of sialic acid metabolism in oral bacteria and discuss its effect on the pathogenesis of colorectal cancer and Alzheimer's disease.

Epigenetic insights to pediatric uropathology: Celebrating the fundamental biology vision of Tony Khoury

INTRODUCTION

Many pediatric urology conditions affect putatively normal tissues or appear too commonly to be based solely on specific DNA mutations. Understanding epigenetic mechanisms in pediatric urology, therefore, has many implications that can impact cell and tissue responses to settings, such as environmental and hormonal influences on urethral development, uropathogenic infections, obstructive stimuli, all of which originate externally or extracellularly. Indeed, the cell's response to external stimuli is often mediated epigenetically. In this commentary, we highlight work on the critical role that epigenetic machinery, such as DNA methyltransferases (DNMTs), Enhancer of Zeste Polycomb Repressive Complex 2 Subunit (EZH2), and others play in regulating gene expression and cellular functions in three urological contexts.

DESIGN

Animal and cellular constructs were used to model clinical pediatric uropathology. The hypertrophy, trabeculation, and fibrosis of the chronically obstructed bladder was explored using smooth muscle cell models employing disorganised vs. normal extracellular matrix (ECM), as well as a new animal model of chronic obstructive bladder disease (COBD) which retains its pathologic features even after bladder de-obstruction. Cell models from human and murine hypospadias or genital tubercles (GT) were used to illustrate developmental responses and epigenetic dependency of key developmental genes. Finally, using bladder urothelial and organoid culture systems, we examined activity of epigenetic machinery in response to non uropathogenic vs. uropathogenic E.coli (UPEC). DNMT and EZH2 expression and function were interrogated in these model systems.

RESULTS

Disordered ECM exerted a principal mitogenic and epigenetic role for on bladder smooth muscle both in vitro and in CODB in vivo. Key genes, e.g., BDNF and KCNB2 were under epigenetic regulation in actively evolving obstruction and COBD, though each condition showed distinct epigenetic responses. In models of hypospadias, estrogen strongly dysregulated WNT and Hox expression, which was normalized by epigenetic inhibition. Finally, DNA methylation machinery in the urothelium showed specific activation when challenged by uropathogenic E.coli. Similarly, UPEC induces hypermethylation and downregulation of the growth suppressor p16INK4A. Moreover, host cells exposed to UPEC produced secreted factors inducing epigenetic responses transmissible from one affected cell to another without ongoing bacterial presence.

DISCUSSION

Microenvironmental influences altered epigenetic activity in the three described urologic contexts. Considering that many obstructed bladders continue to display abnormal architecture and dysfunction despite relief of obstruction similar to after resection of posterior valves or BPH, the epigenetic mechanisms described highlight novel approaches for understanding the underlying smooth muscle myopathy of this crucial clinical problem. Similarly, there is evidence for an epigenetic basis of xenoestrogen on development of hypospadias, and UTI-induced pan-urothelial alteration of epigenetic marks and propensity for subsequent (recurrent) UTI. The impact of mechanical, hormonal, infectious triggers on genitourinary epigenetic machinery activity invite novel avenues for targeting epigenetic modifications associated with these non-cancer diseases in urology. This includes the use of deactivated CRISPR-based technologies for precise epigenome targeting and editing. Overall, we underscore the importance of understanding epigenetic regulation in pediatric urology for the development of innovative therapeutic and management strategies.

An Epigenetic Manifestation of Alzheimer's Disease: DNA Methylation

Alzheimer's disease (AD), the most common form of dementia, has a complex pathogenesis. The number of AD patients has increased in recent years due to population aging, while a trend toward a younger age of onset has arisen, imposing a substantial burden on society and families, and garnering extensive attention. DNA methylation has recently been revealed to play an important role in AD onset and progression. DNA methylation is a critical mechanism regulating gene expression, and alterations in this mechanism dysregulate gene expression and disrupt important pathways, including oxidative stress responses, inflammatory reactions, and protein degradation processes, eventually resulting in disease. Studies have revealed widespread changes in AD patients' DNA methylation in the peripheral blood and brain tissues, affecting multiple signaling pathways and severely impacting neuronal cell and synaptic functions. This review summarizes the role of DNA methylation in the pathogenesis of AD, aiming to provide a theoretical basis for its early prevention and treatment.

Extracellular vesicles and endothelial dysfunction in infectious diseases

Cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity globally. Studies have shown that infections especially bacteraemia and sepsis are associated with increased risks for endothelial dysfunction and related CVDs including atherosclerosis. Extracellular vesicles (EVs) are small, sealed membrane-derived structures that are released into body fluids and blood from cells and/or microbes and are critically involved in a variety of important cell functions and disease development, including intercellular communications, immune responses and inflammation. It is known that EVs-mediated mechanism(s) is important in the development of endothelial dysfunction in infections with a diverse spectrum of microorganisms including Escherichia coli, Candida albicans, SARS-CoV-2 (the virus for COVID-19) and Helicobacter pylori. H. pylori infection is one of the most common infections globally. During H. pylori infection, EVs can carry H. pylori components, such as lipopolysaccharide, cytotoxin-associated gene A, or vacuolating cytotoxin A, and transfer these substances into endothelial cells, triggering inflammatory responses and endothelial dysfunction. This review is to illustrate the important role of EVs in the pathogenesis of infectious diseases, and the development of endothelial dysfunction in infectious diseases especially H. pylori infection, and to discuss the potential mechanisms and clinical implications.

The oral-brain axis: can periodontal pathogens trigger the onset and progression of Alzheimer's disease?

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a progressive cognitive decline. Sporadic AD, accounting for more than 95% of cases, may arise due to the influence of environmental factors. It was reported that periodontitis, a common oral ailment, shares several risk factors with AD, including advanced age, smoking, diabetes, and hypertension, among others. Periodontitis is an inflammatory disease triggered by dysbiosis of oral microorganisms, whereas Alzheimer's disease is characterized by neuroinflammation. Many studies have indicated that chronic inflammation can instigate brain AD-related pathologies, including amyloid-β plaques, Tau protein hyperphosphorylation, neuroinflammation, and neurodegeneration. The potential involvement of periodontal pathogens and/or their virulence factors in the onset and progression of AD by the oral-brain axis has garnered significant attention among researchers with ongoing investigations. This review has updated the periodontal pathogens potentially associated with AD, elucidating their impact on the central nervous system, immune response, and related pathological processes in the brain to provide valuable insights for future research on the oral-brain axis.

Microbial Extracellular Vesicles in Host-Microbiota Interactions

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

Engineered bacterial extracellular vesicles for central nervous system diseases

The prevalence of central nervous system (CNS) diseases is on the rise as the population ages. The presence of various obstacles, particularly the blood-brain barrier (BBB), poses a challenge for drug delivery to the CNS. An expanding body of study suggests that gut microbiota (GM) plays an important role in CNS diseases. The communication between GM and CNS diseases has received increasing attention. Accumulating evidence indicates that the GM can modulate host signaling pathways to regulate distant organ functions by delivering bioactive substances to host cells via bacterial extracellular vesicles (BEVs). BEVs have emerged as a promising platform for the treatment of CNS diseases due to their nanostructure, ability to penetrate the BBB, as well as their low toxicity, high biocompatibility, ease of modification and large-scale culture. Here, we discuss the biogenesis, internalization mechanism and engineering modification methods of BEVs. We then focus on the use and potential role of BEVs in the treatment of CNS diseases. Finally, we outline the main challenges and future prospects for the application of BEVs in CNS diseases. We hope that the comprehensive understanding of the BEVs-based gut-brain axis will provide new insights into the treatment of CNS diseases.

Bacterial extracellular vesicles - brain invaders? A systematic review

Introduction

Knowledge on the human gut microbiota in health and disease continues to rapidly expand. In recent years, changes in the gut microbiota composition have been reported as a part of the pathology in numerous neurodegenerative diseases. Bacterial extracellular vesicles (EVs) have been suggested as a novel mechanism for the crosstalk between the brain and gut microbiota, physiologically connecting the observed changes in the brain to gut microbiota dysbiosis.

Methods

Publications reporting findings on bacterial EVs passage through the blood-brain barrier were identified in PubMed and Scopus databases.

Results

The literature search yielded 138 non-duplicate publications, from which 113 records were excluded in title and abstract screening step. From 25 publications subjected to full-text screening, 8 were excluded. The resulting 17 publications were considered for the review.

Discussion

Bacterial EVs have been described with capability to cross the blood-brain barrier, but the mechanisms behind the crossing remain largely unknown. Importantly, very little data exists in this context on EVs secreted by the human gut microbiota. This systematic review summarizes the present evidence of bacterial EVs crossing the blood-brain barrier and highlights the importance of future research on gut microbiota-derived EVs in the context of gut-brain communication across the blood-brain barrier.

Mouse maternal odontogenic infection with Porphyromonas gingivalis induces cognitive decline in offspring

Introduction

Porphyromonas gingivalis (P. gingivalis), a major periodontal pathogen, causes intrauterine infection/inflammation. Offspring exposed to intrauterine infection/inflammation have an increased risk of neurological disorders, regardless of gestational age. However, the relationship between maternal periodontitis and offspring functional/histological changes in the brain has not yet been elucidated.

Methods

In this study, we used a gestational mouse model to investigate the effects of maternal odontogenic infection of P. gingivalis on offspring behavior and brain tissue.

Results

The step-through passive avoidance test showed that the latency of the acquisition trial was significantly shorter in the P. gingivalis group (p < 0.05), but no difference in spontaneous motor/exploratory parameters by open-field test. P. gingivalis was diffusely distributed throughout the brain, especially in the hippocampus. In the hippocampus and amygdala, the numbers of neuron cells and cyclic adenosine monophosphate response element binding protein-positive cells were significantly reduced (p < 0.05), whereas the number of ionized calcium binding adapter protein 1-positive microglia was significantly increased (p < 0.05). In the hippocampus, the number of glial fibrillary acidic protein-positive astrocytes was also significantly increased (p < 0.05).

Discussion

The offspring of P. gingivalis-infected mothers have reduced cognitive function. Neurodegeneration/neuroinflammation in the hippocampus and amygdala may be caused by P. gingivalis infection, which is maternally transmitted. The importance of eliminating maternal P. gingivalis-odontogenic infection before or during gestation in maintenance healthy brain function in offspring should be addressed in near future.