Porphyromonas gingivalis bacteremia increases the permeability of the blood-brain barrier via the Mfsd2a/Caveolin-1 mediated transcytosis pathway

Interaction of major facilitator superfamily domain containing 2A with the blood-brain barrier

The functional and structural integrity of the blood-brain barrier is crucial in maintaining homeostasis in the brain microenvironment; however, the molecular mechanisms underlying the formation and function of the blood-brain barrier remain poorly understood. The major facilitator superfamily domain containing 2A has been identified as a key regulator of blood-brain barrier function. It plays a critical role in promoting and maintaining the formation and functional stability of the blood-brain barrier, in addition to the transport of lipids, such as docosahexaenoic acid, across the blood-brain barrier. Furthermore, an increasing number of studies have suggested that major facilitator superfamily domain containing 2A is involved in the molecular mechanisms of blood-brain barrier dysfunction in a variety of neurological diseases; however, little is known regarding the mechanisms by which major facilitator superfamily domain containing 2A affects the blood-brain barrier. This paper provides a comprehensive and systematic review of the close relationship between major facilitator superfamily domain containing 2A proteins and the blood-brain barrier, including their basic structures and functions, cross-linking between major facilitator superfamily domain containing 2A and the blood-brain barrier, and the in-depth studies on lipid transport and the regulation of blood-brain barrier permeability. This comprehensive systematic review contributes to an in-depth understanding of the important role of major facilitator superfamily domain containing 2A proteins in maintaining the structure and function of the blood-brain barrier and the research progress to date. This will not only help to elucidate the pathogenesis of neurological diseases, improve the accuracy of laboratory diagnosis, and optimize clinical treatment strategies, but it may also play an important role in prognostic monitoring. In addition, the effects of major facilitator superfamily domain containing 2A on blood-brain barrier leakage in various diseases and the research progress on cross-blood-brain barrier drug delivery are summarized. This review may contribute to the development of new approaches for the treatment of neurological diseases.

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.

Photobiomodulation and the oral-gut microbiome axis: therapeutic potential and challenges

This Perspective article explores the challenges associated with the direct application of photobiomodulation (PBM) to the gut and presents a novel hypothesis for indirect gut health modulation through oral microbiome alteration. Given the difficulties in delivering PBM effectively to deep gastrointestinal tissues, an alternative approach involves targeting the oral microbiome, which has a demonstrated relationship with the gut microbiome. Research indicates that PBM applied to the oral cavity could selectively alter microbial composition. This alteration may, via the oral-gut microbiome axis, indirectly impact gut health. This hypothesis, supported by preliminary studies, suggests that oral PBM could offer a promising non-invasive strategy for managing gut-related disorders. Furthermore, there may be a link between the oral microbiome and brain diseases. Given the proximity to the brain, PBM-induced changes in the oral microbiota could indirectly help prevent neurological disorders. However, further investigation is necessary to comprehensively elucidate the underlying mechanisms and therapeutic implications of this approach.

Porphyromonas gingivalis Induces Disturbance of Kynurenine Metabolism Through the Gut-Brain Axis: Implications for Alzheimer's Disease

Porphyromonas gingivalis is one of the major pathogens of chronic periodontitis. P. gingivalis can cause systemic inflammation, amyloid β protein deposition, and hyperphosphorylation of tau protein, leading to Alzheimer's disease (AD)-like lesions. P. gingivalis oral infection causes gut microbiota alteration, gut barrier dysfunction, and intestinal immune response and inflammation. The microbiota-gut-brain axis has a potential role in the pathogenesis of AD. Whether P. gingivalis affects AD-like lesions via the gut-brain axis needs more study. In this study, orally administered P. gingivalis induced alveolar resorption, intestinal barrier impairment, and AD-like lesions. Oral infection with P. gingivalis induced oral and gut microflora dysbiosis, imbalance of the tryptophan metabolism pathway of gut microbiota, and elevated levels of 3-hydroxykynurenine in the sera and hippocampi. The key metabolite, 3-hydroxykynurenine, suppressed Bcl2 gene expression, leading to neuronal apoptosis and promoting AD-like lesions in vivo and in vitro. These findings suggest that P. gingivalis can induce AD pathogenesis through the gut-brain axis, providing new ideas for the prevention and treatment of AD.

Modulation of lectin-like oxidized low-density lipoprotein receptor-1 by Porphyromonas gingivalis promoting progression of atherosclerosis in apolipoprotein E-/- mice

Background/Purpose

Porphyromonas gingivalis (P. gingivalis), the primary pathogenic bacterium in periodontitis, can infiltrate the cardiovascular system via the bloodstream and actively contribute to various pathological processes associated with atherosclerosis. The scavenger receptor lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays a crucial role in atherosclerosis pathogenesis. Previous studies have shown that LOX-1 is involved in endothelial cell activation injury, monocyte migration, and adhesion to endothelial cells induced by P. gingivalis. The objective of this study was to further investigate the potential role of LOX-1 in promoting P. gingivalis-induced atherosclerosis in mice.

Materials and methods

Using apolipoprotein E (APOE)-/- mice fed with high-fat diet for an established model. Intravenous injection of P. gingivalis was performed to create P. gingivalis blood model while intraperitoneal injection of Polyinosinic-polycytidylic acid (Poly (I:C)) served as an inhibitor for LOX-1. After 12 weeks, plaques and blood lipids were examined.

Results

Results showed that induction with P. gingivalis led to increased expression of LOX-1 in both the aortic root and blood samples, increased plaque area, reduced plaque stability, elevated expression levels of vascular adhesion molecule-1(VCAM-1), Interleukin-6(IL-6) and M1 macrophages. However, pretreatment with Poly (I:C) resulted in decreased plaque area improved plaque stability and reduced expression levels of VCAM-1 and IL-6.

Conclusion

These findings suggest that LOX-1 may serve as an intermediary factor promoting atherosclerosis associated with periodontitis.

Research Trends in the Comorbidity Between Periodontitis and Neurodegenerative Diseases

INTRODUCTION AND AIMS

Evidence suggests an association between periodontitis and neurodegenerative diseases, but a comprehensive analysis of research trends remains absent. Therefore, we aim to identify research trends and hotspots on the comorbidity between periodontitis and neurodegenerative diseases, understand mechanisms, provide guidance for subsequent studies and show its clinical translational possibility.

METHODS

A bibliometric analysis covering 1982 to 2023 was conducted using the Web of Science Core Collection. English-language articles range from January 1, 1982 to November 30, 2023 were analyzed. Data were downloaded on November 30, 2023 and analyzed on December, 2023. Data visualization and statistical analysis were performed to identify trends of annual publications, countries, sources, institutions, authors, most cited articles, and keywords by using Microsoft Excel, VOSviewer, Citespace, R-bibliometrix and Origin Pro.

RESULTS

A total of 1,238 articles from 1982 to 2023 on the comorbidity between periodontitis and neurodegenerative diseases were identified. Annual publications showed an upward trend. The United States, University College of London, BRAIN and Shy, Michael E. were the leading nation, affiliation, source and author, respectively. The United States, NEUROLOGY, and Curtis Maurice A. were the most cited nation, source, and author. Keywords network analysis highlighted 'Charcot-Marie-Tooth Disease', 'Alzheimer's Disease' and 'Periodontitis' as focal points. Detection of keywords citation bursts demonstrated 'Porphyromonas gingivalis' and 'Cognitive Dysfunction' as hot topics in recent research.

CONCLUSIONS

In recent years, emerging interests of the comorbidity between periodontitis and neurodegenerative diseases (NDs) are growing. Our study enhances the understanding of recent research trends of periodontitis and NDs and provides valuable perspectives within this expanding field, offering new insights into research trends regarding the interplay between 'Porphyromonas gingivalis' and 'Cognitive Dysfunction'. Further research of the molecular mechanisms between P. gingivalis-induced periodontitis, neuroinflammation, that leads neurodegeneration are clearly warranted.

Porphyromonas gingivalis exacerbates experimental autoimmune encephalomyelitis by driving Th1 differentiation via ZAP70/NF-κB signaling

Background

Multiple sclerosis (MS) is characterized by chronic inflammation and demyelination within the central nervous system (CNS), primarily driven by the abnormal activation of the peripheral immune system, notably Th1 cells. As the principal pathogen in periodontitis, Porphyromonas gingivalis (P. gingivalis) is linked to an increased risk of multiple sclerosis progression; however, its role in central nervous system inflammation remains unclear. In this study, we aimed to determine whether P. gingivalis promotes peripheral Th1 cell differentiation via the ZAP70/NF-κB signaling pathway, thereby exacerbating experimental autoimmune encephalomyelitis(EAE), a model of multiple sclerosis.

Methods

C57BL/6J mice were randomly divided into healthy control, periodontitis, EAE, and periodontitis with EAE group. Neurological function was assessed using Weaver's score. Histopathology (H&E, LFB staining) and Evans blue dye leakage evaluated inflammation, demyelination, and blood-brain barrier(BBB)permeability. Th1 and Th17 cells were quantified by flow cytometry, while immunofluorescence staining was performed to analyze Claudin-5, IFN-γ +CD4+ T -positive cell and IL-17+CD4+-positive cell expression. Western blotting measured NF-κB and related protein expression. Reference-based mRNA sequencing analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment was conducted to identify differential gene expression and pathway enrichment.

Results

In mice with experimental autoimmune encephalomyelitis, P. gingivalis infection significantly elevated Th1 cell proportions in the peripheral blood, increased interferon-gamma expression, and exacerbated central nervous system inflammation and demyelination by enhancing blood-brain barrier permeability. The infection also activated the ZAP70/NF-κB pathway, essential for peripheral Th1 differentiation, as evidenced by p65 nuclear translocation and significant upregulation of Th1-related genes, including those of the transcription factor Tbx21 and interleukin-12 receptors. In vitro, P. gingivalis lipopolysaccharide (LPS) stimulated Th1 differentiation via ZAP70/NF-κB, which was effectively blocked by pathway inhibitors, reducing Th1 cells and pro-inflammatory factors.

Discussion

Our findings elucidate, for the first time, how P. gingivalis infection promotes central nervous system inflammation by driving Th1 cell differentiation via peripheral ZAP70/NF-κB pathway activation. This highlights P. gingivalis as a local periodontitis pathogen and significant contributor to neuroinflammation, providing new insights into the pathogenesis of multiple sclerosis and identifying promising targets for immunomodulatory therapeutic strategies.

A combination of systemic mannitol and mannitol modified polyester nanoparticles for caveolae-mediated gene delivery to the brain

Overcoming the blood-brain barrier (BBB) remains a significant challenge for nucleic acid delivery to the brain. We have explored a combination of mannitol-modified poly (β-amino ester) (PBAE) nanoparticles and systemic mannitol injection for crossing the BBB. We incorporated mannitol in the PBAE polymer for caveolae targeting and selected monomers that may help avoid delivery to the liver. We also induced caveolae at the BBB through systemic mannitol injection in order to create an opportunity for the caveolae-targeting nanoparticles (M30 D90) containing plasmid DNA to cross the BBB. When a clinically relevant dose was administered intravenously in this caveolae induction model, M30 D90 demonstrated significant transgene expression of a reporter plasmid in the brain, with selective uptake by neuronal cells and minimal liver accumulation. We demonstrate that caveolae modulation using systemic mannitol administration and caveolae targeting using designed nanoparticles are necessary for efficient delivery to the brain. This delivery platform offers a simple, scalable, and controlled delivery solution and holds promise for treating brain diseases with functional targets.

Caveolin-1-mediated LDL transcytosis across endothelial cells in atherosclerosis

Atherosclerosis is widely recognized as a chronic inflammatory disease of the arterial wall characterized by the progressive accumulation of lipids, inflammatory cells, and fibrous material in the subendothelial space of large arteries. The occurrence and pathogenesis of atherosclerosis are intricately linked to the deposition of low-density lipoprotein (LDL) in the arterial wall. LDL must cross the intact endothelium to reach the subendothelial space, with caveolin-1 assuming a crucial role in this process. Caveolin-1 is a 21-24 kDa membrane protein located in caveolae and highly expressed in endothelial cells. Previous investigations have demonstrated the pivotal role of caveolin-1 in fostering atherosclerosis through its modulation of membrane trafficking, cholesterol metabolism, and cellular signaling. However, how caveolin-1 regulates LDL transcytosis across endothelial cells in atherosclerosis remains unclear. We provide a comprehensive overview of recent research on the interplay between caveolin-1 and atherosclerosis, with a specific focus on elucidating the role of caveolin-1 in mediating LDL transcytosis across endothelial cells. This review furnishes theoretical foundations supporting the pivotal role of caveolin-1 in both the inception and progression of atherosclerosis. It underscores the prospective viability of caveolin-1 as a new therapeutic target for atherosclerosis and introduces novel perspectives for treatment strategies in the early stages of atherosclerosis.

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.

The impact of aging on neutrophil functions and the contribution to periodontitis

The increasing aging population and aging-associated diseases have become a global issue for decades. People over 65 show an increased prevalence and greater severity of periodontitis, which poses threats to overall health. Studies have demonstrated a significant association between aging and the dysfunction of neutrophils, critical cells in the early stages of periodontitis, and their crosstalk with macrophages and T and B lymphocytes to establish the periodontal lesion. Neutrophils differentiate and mature in the bone marrow before entering the circulation; during an infection, they are recruited to infected tissues guided by the signal from chemokines and cytokines to eliminate invading pathogens. Neutrophils are crucial in maintaining a balanced response between host and microbes to prevent periodontal diseases in periodontal tissues. The impacts of aging on neutrophils' chemotaxis, anti-microbial function, cell activation, and lifespan result in impaired neutrophil functions and excessive neutrophil activation, which could influence periodontitis course. We summarize the roles of neutrophils in periodontal diseases and the aging-related impacts on neutrophil functional responses. We also explore the underlying mechanisms that can contribute to periodontitis manifestation in aging. This review could help us better understand the pathogenesis of periodontitis, which could offer novel therapeutic targets for periodontitis.

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.

Caveolin-Mediated Endocytosis: Bacterial Pathogen Exploitation and Host-Pathogen Interaction

Within mammalian cells, diverse endocytic mechanisms, including phagocytosis, pinocytosis, and receptor-mediated endocytosis, serve as gateways exploited by many bacterial pathogens and toxins. Among these, caveolae-mediated endocytosis is characterized by lipid-rich caveolae and dimeric caveolin proteins. Caveolae are specialized microdomains on cell surfaces that impact cell signaling. Caveolin proteins facilitate the creation of caveolae and have three members in vertebrates: caveolin-1, caveolin-2, and caveolin-3. Many bacterial pathogens hijack caveolin machinery to invade host cells. For example, the Gram-positive facultative model intracellular bacterial pathogen Listeria monocytogenes exploits caveolin-mediated endocytosis for efficient cellular entry, translocation across the intestinal barrier, and cell-cell spread. Caveolin facilitates the internalization of group A streptococci by promoting the formation of invaginations in the plasma membrane and avoiding fusion with lysosomes, thereby aiding intracellular survival. Caveolin plays a crucial role in internalizing and modulation of host immune responses by Gram-negative bacterial pathogens, such as Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium. Here, we summarize how bacterial pathogens manipulate the host's caveolin system to facilitate bacterial entry and movement within and between host cells, to support intracellular survival, to evade immune responses, and to trigger inflammation. This knowledge enhances the intervention of new therapeutic targets against caveolin in microbial invasion and immune evasion processes.

Increased caveolin 1 by human antigen R exacerbates Porphyromonas gingivali-induced atherosclerosis by modulating oxidative stress and inflammatory responses

Objective

Many different types of infectious oral diseases have been identified clinically, including chronic periodontitis. Porphyromonas gingivalis is the main pathogen causing chronic periodontitis, which is closely related to atherosclerosis (AS) and can promote the expression levels of caveolin 1 (Cav-1) and induced ribonucleic acid (RNA)-binding protein human antigen R (HuR). However, the roles of Cav-1 and its relationship with HuR in P. gingivalis-mediated AS progression remain largely unknown. Here, we aimed to detect the role and molecular mechanisms of Cav-1 in P. gingivalis-mediated AS.

Material and Methods

To investigate the role of Cav-1 in P. gingivalis-mediated AS, we infected human umbilical vein endothelial cells (HUVECs) with P. gingivalis at a multiplicity of infection of 100:1 for 6, 12, and 24 h to simulate P. gingivalis-induced AS models in vitro and then transfected them with Cav-1 small interfering RNA to silence Cav-1. Combining molecular biology experimental techniques such as cell counting kit-8 assay, enzyme-linked immunosorbent assay, immunofluorescence staining, flow cytometry, Western blotting, and Oil Red O staining, and apolipoprotein E-deficient AS model mice, the impacts of Cav-1 on cell viability, inflammation, oxidative stress, apoptosis, Cav-1 and intercellular cell adhesion molecule-1 (ICAM-1) levels, and atherosclerotic plaque formation were investigated. Then, the relationship between Cav-1 and HuR was investigated through biotin pull-down and RNA immunoprecipitation assays, reverse transcription quantitative polymerase chain reaction, and Western blot.

Results

P. gingivalis can induce Cav-1 expression in a time- and dose-dependent manner (P < 0.05). This effect can inhibit the proliferation of HUVECs (P < 0.05). Cav-1 interference repressed inflammatory response, reactive oxygen species (ROS) and ICAM-1 levels, and apoptosis in the HUVECs (P < 0.05). Cav-1 messenger RNA was stabilized by HuR, which can bind to the 3' untranslated region of Cav-1. Increase in HuR level reversed the effects of Cav-1 silencing on ROS and ICAM-1 levels and apoptosis in the HUVECs (P < 0.05). In addition, the levels of inflammatory response, oxidative stress, and atherosclerotic plaque formation induced by P. gingivalis in the mouse model were significantly reduced after Cav-1 expression was inhibited (P < 0.05).

Conclusion

HuR-activated Cav-1 may promote atherosclerotic plaque formation by modulating inflammatory response and oxidative stress, leading to AS.

Potential mechanisms of Treponema pallidum breaching the blood-brain barrier

Syphilis, a sexually transmitted disease caused by Treponema pallidum subsp. pallidum (T. pallidum), can lead to a complication known as neurosyphilis. Neurosyphilis affects multiple components of the nervous system, including the meninges, blood vessels, brain parenchyma, and others, significantly impacting the central nervous system (CNS). Despite the effective control of syphilis spread by antibiotics, recent years have seen a resurgence in incidence among high-risk populations. The blood-brain barrier (BBB) is a critical defense for the CNS, preventing toxins and pathogens, including viruses, from entering and ensuring CNS function. The exact mechanisms of how T. pallidum penetrates the BBB are still not fully understood. Extensive research suggests that T. pallidum can disrupt endothelial cells and intercellular junctions, as well as induce abnormal activation of immune cells and aberrant cytokine expression, potentially facilitating its breach of BBB. Based on current research, we focus on the detrimental effects of cytokines on BBB integrity. We have also summarized the pathways T. pallidum uses to penetrate cellular barriers. Understanding the interaction between T. pallidum and the BBB is essential for revealing neurosyphilis pathogenesis and developing new therapies. DATA AVAILABILITY: Data used to support the findings of this study are included in the article.

Current status and prospect of gut and oral microbiome in pancreatic cancer: Clinical and translational perspectives

Pancreatic cancer is a highly lethal malignancy, and its diagnosis and treatment continue to pose significant challenges. Despite advancements in surgical and comprehensive treatment methods, the five-year survival rate remains below 12 %. With the rapid development of microbiome science, the gut and oral microbiota, which are readily accessible and can be sampled non-invasively, have emerged as a novel area of interest in pancreatic cancer research. Dysbiosis in these microbial communities can induce persistent inflammatory responses and affect the host's immune system, promoting cancer development and impacting the efficacy of treatments like chemotherapy and immunotherapy. This review provides an up-to-date overview of the roles of both gut and oral microbiota in the onset, progression, diagnosis, and treatment of pancreatic cancer. It analyzes the potential of utilizing these microbiomes as biomarkers and therapeutic targets from a clinical application perspective. Furthermore, it discusses future research directions aimed at harnessing these insights to advance the diagnosis and treatment strategies for pancreatic cancer. By focusing on the microbiome's role in clinical and translational medicine, this review offers insights into improving pancreatic cancer diagnosis and treatment outcomes.

Compromised endothelial Wnt/β-catenin signaling mediates the blood-brain barrier disruption and leads to neuroinflammation in endotoxemia

The blood-brain barrier (BBB) is a critical interface that maintains the central nervous system homeostasis by controlling the exchange of substances between the blood and the brain. Disruption of the BBB plays a vital role in the development of neuroinflammation and neurological dysfunction in sepsis, but the mechanisms by which the BBB becomes disrupted during sepsis are not well understood. Here, we induced endotoxemia, a major type of sepsis, in mice by intraperitoneal injection of lipopolysaccharide (LPS). LPS acutely increased BBB permeability, activated microglia, and heightened inflammatory responses in brain endothelium and parenchyma. Concurrently, LPS or proinflammatory cytokines activated the NF-κB pathway, inhibiting Wnt/β-catenin signaling in brain endothelial cells in vitro and in vivo. Cell culture study revealed that NF-κB p65 directly interacted with β-catenin to suppress Wnt/β-catenin signaling. Pharmacological NF-κB pathway inhibition restored brain endothelial Wnt/β-catenin signaling activity and mitigated BBB disruption and neuroinflammation in septic mice. Furthermore, genetic or pharmacological activation of brain endothelial Wnt/β-catenin signaling substantially alleviated LPS-induced BBB leakage and neuroinflammation, while endothelial conditional ablation of the Wnt7a/7b co-receptor Gpr124 exacerbated the BBB leakage caused by LPS. Mechanistically, Wnt/β-catenin signaling activation rectified the reduced expression levels of tight junction protein ZO-1 and transcytosis suppressor Mfsd2a in brain endothelial cells of mice with endotoxemia, inhibiting both paracellular and transcellular permeability of the BBB. Our findings demonstrate that endotoxemia-associated systemic inflammation decreases endothelial Wnt/β-catenin signaling through activating NF-κB pathway, resulting in acute BBB disruption and neuroinflammation. Targeting the endothelial Wnt/β-catenin signaling may offer a promising therapeutic strategy for preserving BBB integrity and treating neurological dysfunction in sepsis.

MAD-microbial (origin of) Alzheimer's disease hypothesis: from infection and the antimicrobial response to disruption of key copper-based systems

Microbes have been suspected to cause Alzheimer's disease since at least 1908, but this has generally remained unpopular in comparison to the amyloid hypothesis and the dominance of Aβ and Tau. However, evidence has been accumulating to suggest that these earlier theories are but a manifestation of a common cause that can trigger and interact with all the major molecular players recognized in AD. Aβ, Tau and ApoE, in particular appear to be molecules with normal homeostatic functions but also with alternative antimicrobial functions. Their alternative functions confer the non-immune specialized neuron with some innate intracellular defenses that appear to be re-appropriated from their normal functions in times of need. Indeed, signs of infection of the neurons by biofilm-forming microbial colonies, in synergy with herpes viruses, are evident from the clinical and preclinical studies we discuss. Furthermore, we attempt to provide a mechanistic understanding of the AD landscape by discussing the antimicrobial effect of Aβ, Tau and ApoE and Lactoferrin in AD, and a possible mechanistic link with deficiency of vital copper-based systems. In particular, we focus on mitochondrial oxidative respiration via complex 4 and ceruloplasmin for iron homeostasis, and how this is similar and possibly central to neurodegenerative diseases in general. In the case of AD, we provide evidence for the microbial Alzheimer's disease (MAD) theory, namely that AD could in fact be caused by a long-term microbial exposure or even long-term infection of the neurons themselves that results in a costly prolonged antimicrobial response that disrupts copper-based systems that govern neurotransmission, iron homeostasis and respiration. Finally, we discuss potential treatment modalities based on this holistic understanding of AD that incorporates the many separate and seemingly conflicting theories. If the MAD theory is correct, then the reduction of microbial exposure through use of broad antimicrobial and anti-inflammatory treatments could potentially alleviate AD although this requires further clinical investigation.

Peri-implantitis with a potential axis to brain inflammation: an inferential review

Peri-implantitis (PI) is a chronic, inflammatory, and infectious disease which affects dental implants and has certain similarities to periodontitis (PD). Evidence has shown that PD may be related to several types of systemic disorders, such as diabetes and insulin resistance, cardiovascular diseases, respiratory tract infections, adverse pregnancy outcomes, and neurological disorders. Furthermore, some types of bacteria in PD can also be found in PI, leading to certain similarities in the immunoinflammatory responses in the host. This review aims to discuss the possible connection between PI and neuroinflammation, using information based on studies about periodontal disorders, a topic whose connection with systemic alterations has been gaining the interest of the scientific community. Literature concerning PI, PD, and systemic disorders, such as neuroinflammation, brain inflammation, and neurological disorder, was searched in the PubMed database using different keyword combinations. All studies found were included in this narrative review. No filters were used. Eligible studies were analyzed and reviewed carefully. This study found similarities between PI and PD development, maintenance, and in the bacterial agents located around the teeth (periodontitis) or dental implants (peri-implantitis). Through the cardiovascular system, these pathologies may also affect blood-brain barrier permeability. Furthermore, scientific evidence has suggested that microorganisms from PI (as in PD) can be recognized by trigeminal fiber endings and start inflammatory responses into the trigeminal ganglion. In addition, bacteria can traverse from the mouth to the brain through the lymphatic system. Consequently, the immune system increases inflammatory mediators in the brain, affecting the homeostasis of the nervous tissue and vice-versa. Based on the interrelation of microbiological, inflammatory, and immunological findings between PD and PI, it is possible to infer that immunoinflammatory changes observed in PD can imply systemic changes in PI. This, as discussed, could lead to the development or intensification of neuroinflammatory changes, contributing to neurodegenerative diseases.

Caveolin Regulates the Transport Mechanism of the Walnut-Derived Peptide EVSGPGYSPN to Penetrate the Blood-Brain Barrier

Bioactive peptides, derived from short protein fragments, are recognized for their neuroprotective properties and potential therapeutic applications in treating central nervous system (CNS) diseases. However, a significant challenge for these peptides is their ability to penetrate the blood-brain barrier (BBB). EVSGPGYSPN (EV-10) peptide, a walnut-derived peptide, has demonstrated promising neuroprotective effects in vivo. This study aimed to investigate the transportability of EV-10 across the BBB, explore its capacity to penetrate this barrier, and elucidate the regulatory mechanisms underlying peptide-induced cellular internalization and transport pathways within the BBB. The results indicated that at a concentration of 100 μM and osmotic time of 4 h, the apparent permeability coefficient of EV-10 was Papp = 8.52166 ± 0.58 × 10-6 cm/s. The penetration efficiency of EV-10 was influenced by time, concentration, and temperature. Utilizing Western blot analysis, immunofluorescence, and flow cytometry, in conjunction with the caveolin (Cav)-specific inhibitor M-β-CD, we confirmed that EV-10 undergoes transcellular transport through a Cav-dependent endocytosis pathway. Notably, the tight junction proteins ZO-1, occludin, and claudin-5 were not disrupted by EV-10. Throughout its transport, EV-10 was localized within the mitochondria, Golgi apparatus, endoplasmic reticulum, lysosomes, endosomes, and cell membranes. Moreover, Cav-1 overexpression facilitated the release of EV-10 from lysosomes. Evidence of EV-10 accumulation was observed in mouse brains using brain slice scans. This study is the first to demonstrate that Cav-1 can facilitate the targeted delivery of walnut-derived peptide to the brain, laying a foundation for the development of functional foods aimed at CNS disease intervention.

Advancements in strategies for overcoming the blood-brain barrier to deliver brain-targeted drugs

The blood-brain barrier is known to consist of a variety of cells and complex inter-cellular junctions that protect the vulnerable brain from neurotoxic compounds; however, it also complicates the pharmacological treatment of central nervous system disorders as most drugs are unable to penetrate the blood-brain barrier on the basis of their own structural properties. This dramatically diminished the therapeutic effect of the drug and compromised its biosafety. In response, a number of drugs are often delivered to brain lesions in invasive ways that bypass the obstruction of the blood-brain barrier, such as subdural administration, intrathecal administration, and convection-enhanced delivery. Nevertheless, these intrusive strategies introduce the risk of brain injury, limiting their clinical application. In recent years, the intensive development of nanomaterials science and the interdisciplinary convergence of medical engineering have brought light to the penetration of the blood-brain barrier for brain-targeted drugs. In this paper, we extensively discuss the limitations of the blood-brain barrier on drug delivery and non-invasive brain-targeted strategies such as nanomedicine and blood-brain barrier disruption. In the meantime, we analyze their strengths and limitations and provide outlooks on the further development of brain-targeted drug delivery systems.

Gingipain from Porphyromonas gingivalis causes insulin resistance by degrading insulin receptors through direct proteolytic effects

Periodontitis is a critical risk factor for the occurrence and development of diabetes. Porphyromonas gingivalis may participate in insulin resistance (IR) caused by periodontal inflammation, but the functional role and specific mechanisms of P. gingivalis in IR remain unclear. In the present study, clinical samples were analysed to determine the statistical correlation between P. gingivalis and IR occurrence. Through culturing of hepatocytes, myocytes, and adipocytes, and feeding mice P. gingivalis orally, the functional correlation between P. gingivalis and IR occurrence was further studied both in vitro and in vivo. Clinical data suggested that the amount of P. gingivalis isolated was correlated with the Homeostatic Model Assessment for IR score. In vitro studies suggested that coculture with P. gingivalis decreased glucose uptake and insulin receptor (INSR) protein expression in hepatocytes, myocytes, and adipocytes. Mice fed P. gingivalis tended to undergo IR. P. gingivalis was detectable in the liver, skeletal muscle, and adipose tissue of experimental mice. The distribution sites of gingipain coincided with the downregulation of INSR. Gingipain proteolysed the functional insulin-binding region of INSR. Coculture with P. gingivalis significantly decreased the INSR-insulin binding ability. Knocking out gingipain from P. gingivalis alleviated the negative effects of P. gingivalis on IR in vivo. Taken together, these findings indicate that distantly migrated P. gingivalis may directly proteolytically degrade INSR through gingipain, thereby leading to IR. The results provide a new strategy for preventing diabetes by targeting periodontal pathogens and provide new ideas for exploring novel mechanisms by which periodontal inflammation affects the systemic metabolic state.

Recent advances in the pathogenesis and prevention strategies of dental calculus

Dental calculus severely affects the oral health of humans and animal pets. Calculus deposition affects the gingival appearance and causes inflammation. Failure to remove dental calculus from the dentition results in oral diseases such as periodontitis. Apart from adversely affecting oral health, some systemic diseases are closely related to dental calculus deposition. Hence, identifying the mechanisms of dental calculus formation helps protect oral and systemic health. A plethora of biological and physicochemical factors contribute to the physiological equilibrium in the oral cavity. Bacteria are an important part of the equation. Calculus formation commences when the bacterial equilibrium is broken. Bacteria accumulate locally and form biofilms on the tooth surface. The bacteria promote increases in local calcium and phosphorus concentrations, which triggers biomineralization and the development of dental calculus. Current treatments only help to relieve the symptoms caused by calculus deposition. These symptoms are prone to relapse if calculus removal is not under control. There is a need for a treatment regime that combines short-term and long-term goals in addressing calculus formation. The present review introduces the mechanisms of dental calculus formation, influencing factors, and the relationship between dental calculus and several systemic diseases. This is followed by the presentation of a conceptual solution for improving existing treatment strategies and minimizing recurrence.

Gingipains may be one of the key virulence factors of Porphyromonas gingivalis to impair cognition and enhance blood-brain barrier permeability: An animal study

AIM

Blood-brain barrier (BBB) disorder is one of the early findings in cognitive impairments. We have recently found that Porphyromonas gingivalis bacteraemia can cause cognitive impairment and increased BBB permeability. This study aimed to find out the possible key virulence factors of P. gingivalis contributing to the pathological process.

MATERIALS AND METHODS

C57/BL6 mice were infected with P. gingivalis or gingipains or P. gingivalis lipopolysaccharide (P. gingivalis LPS group) by tail vein injection for 8 weeks. The cognitive behaviour changes in mice, the histopathological changes in the hippocampus and cerebral cortex, the alternations of BBB permeability, and the changes in Mfsd2a and Cav-1 levels were measured. The mechanisms of Ddx3x-induced regulation on Mfsd2a by arginine-specific gingipain A (RgpA) in BMECs were explored.

RESULTS

P. gingivalis and gingipains significantly promoted mice cognitive impairment, pathological changes in the hippocampus and cerebral cortex, increased BBB permeability, inhibited Mfsd2a expression and up-regulated Cav-1 expression. After RgpA stimulation, the permeability of the BBB model in vitro increased, and the Ddx3x/Mfsd2a/Cav-1 regulatory axis was activated.

CONCLUSIONS

Gingipains may be one of the key virulence factors of P. gingivalis to impair cognition and enhance BBB permeability by the Ddx3x/Mfsd2a/Cav-1 axis.

Contribution of CNS and extra-CNS infections to neurodegeneration: a narrative review

Central nervous system infections have been suggested as a possible cause for neurodegenerative diseases, particularly sporadic cases. They trigger neuroinflammation which is considered integrally involved in neurodegenerative processes. In this review, we will look at data linking a variety of viral, bacterial, fungal, and protozoan infections to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis and unspecified dementia. This narrative review aims to bring together a broad range of data currently supporting the involvement of central nervous system infections in the development of neurodegenerative diseases. The idea that no single pathogen or pathogen group is responsible for neurodegenerative diseases will be discussed. Instead, we suggest that a wide range of susceptibility factors may make individuals differentially vulnerable to different infectious pathogens and subsequent pathologies.

Isobavachin attenuates osteoclastogenesis and periodontitis-induced bone loss by inhibiting cellular iron accumulation and mitochondrial biogenesis

As bone-resorbing cells rich in mitochondria, osteoclasts require high iron uptake to promote mitochondrial biogenesis and maintain a high-energy metabolic state for active bone resorption. Given that abnormal osteoclast formation and activation leads to imbalanced bone remodeling and osteolytic bone loss, osteoclasts may be crucial targets for treating osteolytic diseases such as periodontitis. Isobavachin (IBA), a natural flavonoid compound, has been confirmed to be an inhibitor of receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs). However, its effects on periodontitis-induced bone loss and the potential mechanism of its anti-osteoclastogenesis effect remain unclear. Our study demonstrated that IBA suppressed RANKL-induced osteoclastogenesis in BMMs and RAW264.7 cells and inhibited osteoclast-mediated bone resorption in vitro. Transcriptomic analysis indicated that iron homeostasis and reactive oxygen species (ROS) metabolic process were enriched among the differentially expressed genes following IBA treatment. IBA exerted its anti-osteoclastogenesis effect by inhibiting iron accumulation in osteoclasts. Mechanistically, IBA attenuated iron accumulation in RANKL-induced osteoclasts by inhibiting the mitogen-activated protein kinase (MAPK) pathway to upregulate ferroportin1 (Fpn1) expression and promote Fpn1-mediated intracellular iron efflux. We also found that IBA inhibited mitochondrial biogenesis and function, and reduced RANKL-induced ROS generation in osteoclasts. Furthermore, IBA attenuated periodontitis-induced bone loss by reducing osteoclastogenesis in vivo. Overall, these results suggest that IBA may serve as a promising therapeutic strategy for bone diseases characterized by osteoclastic bone resorption.

Ultrastructural localization of Porphyromonas gingivalis gingipains in the substantia nigra of Parkinson's disease brains

Gingipains are protease virulence factors produced by Porphyromonas gingivalis, a Gram-negative bacterium best known for its role in chronic periodontitis. Gingipains were recently identified in the middle temporal gyrus of postmortem Alzheimer's disease (AD) brains, where gingipain load correlated with AD diagnosis and tau and ubiquitin pathology. Since AD and Parkinson's disease (PD) share some overlapping pathologic features, including nigral pathology and Lewy bodies, the current study explored whether gingipains are present in the substantia nigra pars compacta of PD brains. In immunohistochemical techniques and multi-channel fluorescence studies, gingipain antigens were abundant in dopaminergic neurons in the substantia nigra of both PD and neurologically normal control brains. 3-dimensional reconstructions of Lewy body containing neurons revealed that gingipains associated with the periphery of alpha-synuclein aggregates but were occasionally observed inside aggregates. In vitro proteomic analysis demonstrated that recombinant alpha-synuclein is cleaved by lysine-gingipain, generating multiple alpha-synuclein fragments including the non-amyloid component fragments. Immunogold electron microscopy with co-labeling of gingipains and alpha-synuclein confirmed the occasional colocalization of gingipains with phosphorylated (pSER129) alpha-synuclein. In dopaminergic neurons, gingipains localized to the perinuclear cytoplasm, neuromelanin, mitochondria, and nucleus. These data suggest that gingipains localize in dopaminergic neurons in the substantia nigra and interact with alpha-synuclein.

Phthalates Induce Neurotoxicity by Disrupting the Mfn2-PERK Axis-Mediated Endoplasmic Reticulum-Mitochondria Interaction

Di-(2-ethylhexyl) phthalate (DEHP), as the most common phthalate, has been extensively used as a plasticizer to improve the plasticity of agricultural products, which pose severe harm to human health. Mitochondrial dynamics and endoplasmic reticulum (ER) homeostasis are indispensable for maintaining mitochondria-associated ER membrane (MAM) integrity. In this study, we aimed to explore the effect of DEHP on the nervous system and its association with the ER-mitochondria interaction. Here, we showed that DEHP caused morphological changes, motor deficits, cognitive impairments, and blood-brain barrier disruption in the brain. DEHP triggered ER stress, which is mainly mediated by protein kinase R-like endoplasmic reticulum kinase (PERK) signaling. Moreover, DEHP-induced mitofusin-2 (Mfn2) downregulation results in imbalance of the mitochondrial dynamics. Interestingly, DEHP exposure impaired MAMs by inhibiting the Mfn2-PERK interaction. Above all, this study elucidates the disruption of the Mfn2-PERK axis-mediated ER-mitochondria interaction as a phthalate-induced neurotoxicity that could be potentially developed as a novel therapy for neurological diseases.

Periodontal and Systemic Diseases: A Descriptive Analysis of Awareness Among the General Saudi Population

Background Taking into account the limited availability of research data, this study aimed to determine the general Saudi population's awareness of the link between periodontal diseases and systemic diseases. Methodology A structured online questionnaire with eight awareness items, apart from demographic variables, was distributed through email, WhatsApp, and Telegram to a sample of 500 individuals. The data were analyzed using a simple descriptive statistical approach and interpreted as ratios for comparison. The awareness regarding systemic diseases associated with periodontal diseases was classified into the following four categories based on the Bloom cutoff points: high (>80%), average (60-79%), low (40-59%), and extremely low (<40%). Results A response rate of 68% was reached with the participation of 340 Saudi citizens residing in the Al Qassim region. Overall, 61.22% of research participants had an average awareness of the link between periodontal and systemic diseases. Almost two-thirds (>60%) of participants were aware that periodontal diseases and systemic diseases have an association and that individuals with systemic diseases need a periodontal checkup. A majority (85%) of participants opined that periodontal treatment has the potential to enhance overall health. Nonetheless, only a few participants (60%) were aware of the association between diabetes mellitus and periodontal diseases, and they had a limited awareness of the association with other systemic diseases. Conclusions Although the Saudi general population possesses average awareness about the relationship between periodontal diseases and systemic diseases, their awareness about different systemic diseases and conditions is extremely low, particularly regarding infertility, stroke, and metabolic diseases. The present research indicates a deficiency in the efforts by healthcare professionals, community service providers, and community administrators to educate the general public regarding the association between periodontal diseases and systemic diseases. This awareness is crucial for individuals to control these intricate, interconnected diseases.

Potential Association of the Oral Microbiome with Trimethylamine N-Oxide Quantification in Mexican Patients with Myocardial Infarction

Many attempts have been proposed to evaluate the linkage between the oral-gut-liver axis and the mechanisms related to the diseases' establishment. One of them is the oral microbiota translocation into the bloodstream, liver, and gut, promoting a host dysbiosis and triggering the presence of some metabolites such as trimethylamine N-oxide (TMAO), known as a risk marker for cardiovascular disease, and especially the myocardial infarction (MI). In the present pilot study, the involvement of oral dysbiosis related to the presence of TMAO has been considered an independent component of the standard risk factors (SRs) in the development of MI, which has not been previously described in human cohorts. A positive and significant correlation of TMAO levels with Porphyromonas was identified; likewise, the increase of the genus Peptidiphaga in patients without SRs was observed. We determined that the presence of SRs does not influence the TMAO concentration in these patients. This report is the first study where the relationship between oral dysbiosis and TMAO is specified in the Mexican population. Our findings provide information on the possible contribution of the oral pathogens associated with gut dysbiosis in the development of MI, although further analysis should be performed.

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.

Dysregulation of Porphyromonas gingivalis Agmatine Deiminase Expression in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, with a significant burden on global health. AD is characterized by a progressive cognitive decline and memory loss. Emerging research suggests a potential link between periodontitis, specifically the presence of oral bacteria such as Porphyromonas gingivalis (P. gingivalis), and AD progression. P. gingivalis produces an enzyme, Agmatine deiminase (AgD), which converts agmatine to N-carbamoyl putrescine (NCP), serving as a precursor to essential polyamines. Recent studies have confirmed the correlation between disruptions in polyamine metabolism and cognitive impairment.

OBJECTIVE

This study aims to investigate the dysregulation of P. gingivalis Agmatine deiminase (PgAgD) in the context of AD.

METHODS

Saliva samples were collected from a total of 54 individuals, including 27 AD patients and 27 healthy controls. The expression of the PgAgD gene was analyzed using quantitative Real-- Time PCR.

RESULTS

The results showed a significant decrease in PgAgD gene expression in the saliva samples of AD patients compared to healthy controls. This downregulation was found in AD patients with advanced stages of periodontitis. Additionally, a correlation was observed between the decrease in PgAgD expression and the 30-item Mini-Mental State Examination (MMSE) score.

CONCLUSION

These findings suggest that measuring PgAgD expression in saliva could be a noninvasive tool for monitoring AD progression and aid in the early diagnosis of patients with periodontitis. Further research is needed to validate our results and explore the underlying mechanisms linking periodontitis, PgAgD expression, and AD pathophysiology.

Hydroxyapatite-Coated Small Intestinal Submucosa Membranes Enhanced Periodontal Tissue Regeneration through Immunomodulation and Osteogenesis via BMP-2/Smad Signaling Pathway

Periodontitis, a chronic infection causing periodontal tissue loss, may be effectively addressed with in situ tissue engineering. Small intestinal submucosa (SIS) offers exceptional biocompatibility and biodegradability but lacks sufficient osteoconductive and osteoinductive properties. This study develops and characterizes SIS coated with hydroxyapatite (SIS-HA) and gelatin methacrylate hydroxyapatite (SIS-Gel-HA) using biomineralization and chemical crosslinking. The impact on periodontal tissue regeneration is assessed by evaluating macrophage immune response and osteogenic differentiation potential of periodontal ligament stem cells (PDLSCs) in vitro and rat periodontal defects in vivo. The jejunum segment, with the highest collagen type I content, is optimal for SIS preparation. SIS retains collagen fiber structure and bioactive factors. Calcium content is 2.21% in SIS-HA and 2.45% in SIS-Gel-HA, with no significant differences in hydrophilicity, physicochemical properties, protein composition, or biocompatibility among SIS, SIS-HA, SIS-Gel, and SIS-Gel-HA. SIS is found to upregulate M2 marker expression, both SIS-HA and SIS-Gel-HA enhance the osteogenic differentiation of PDLSCs through the BMP-2/Smad signaling pathway, and SIS-HA demonstrates superior in vitro osteogenic activity. In vivo, SIS-HA and SIS-Gel-HA yield denser, more mature bones with the highest BMP-2 and Smad expression. SIS-HA and SIS-Gel-HA demonstrate enhanced immunity-osteogenesis coupling, representing a promising periodontal tissue regeneration approach.

Engineered exosomes derived from stem cells: a new brain-targeted strategy

INTRODUCTION

Using engineered exosomes produced from stem cells is an experimental therapeutic approach for treating brain diseases. According to reports, preclinical research has demonstrated notable neurogenesis and angiogenesis effects using modified stem cell-derived exosomes. These biological nanoparticles have a variety of anti-apoptotic, anti-inflammatory, and antioxidant properties that make them very promising for treating nervous system disorders.

AREAS COVERED

This review examines different ways to enhance the delivery of modified stem cell-derived exosomes, how they infiltrate the blood-brain barrier (BBB), and how they facilitate their access to the brain. We would also like to determine whether these nanoparticles have the most significant transmission rates through BBB when targeting brain lesions.

EXPERT OPINION

Using engineered stem cell-derived exosomes for treating brain disorders has generated considerable attention toward clinical research and application. However, stem cell-derived exosomes lack consistency, and their mechanisms of action are uncertain. Therefore, upcoming research needs to prioritize examining the underlying mechanisms and strategies via which these nanoparticles combat neurological disorders.

Advances in the prevention and treatment of Alzheimer's disease based on oral bacteria

With the global population undergoing demographic shift towards aging, the prevalence of Alzheimer's disease (AD), a prominent neurodegenerative disorder that primarily afflicts individuals aged 65 and above, has increased across various geographical regions. This phenomenon is accompanied by a concomitant decline in immune functionality and oral hygiene capacity among the elderly, precipitating compromised oral functionality and an augmented burden of dental plaque. Accordingly, oral afflictions, including dental caries and periodontal disease, manifest with frequency among the geriatric population worldwide. Recent scientific investigations have unveiled the potential role of oral bacteria in instigating both local and systemic chronic inflammation, thereby delineating a putative nexus between oral health and the genesis and progression of AD. They further proposed the oral microbiome as a potentially modifiable risk factor in AD development, although the precise pathological mechanisms and degree of association have yet to be fully elucidated. This review summarizes current research on the relationship between oral bacteria and AD, describing the epidemiological and pathological mechanisms that may potentially link them. The purpose is to enrich early diagnostic approaches by incorporating emerging biomarkers, offering novel insights for clinicians in the early detection of AD. Additionally, it explores the potential of vaccination strategies and guidance for clinical pharmacotherapy. It proposes the development of maintenance measures specifically targeting oral health in older adults and advocates for guiding elderly patients in adopting healthy lifestyle habits, ultimately aiming to indirectly mitigate the progression of AD while promoting oral health in the elderly.

Formulation and Evaluation of PLGA Nanoparticulate-Based Microneedle System for Potential Treatment of Neurological Diseases

Introduction

The tight structure of the blood-brain barrier severely limits the level of drug therapy for central nervous system disorders. In this study, a novel composite delivery system combining nanocarrier and microneedle technology was prepared to explore the possibility of transdermal delivery of drugs to work in the brain.

Methods

Nanoparticle solutions containing paroxetine and rhodamine-B were prepared using PLGA as a carrier by the emulsification-solvent volatilization method. Then, they were mixed with hyaluronic acid and the PLGA nanoparticulate-based microneedle system (Rh-NPs-DMNs) was prepared by a multi-step decompression-free diffusion method. The particle size, zeta potential, and micromorphology of the nano solution were measured; the appearance, mechanical strength, dissolution properties, and puncture effect of the Rh-NPs-DMNs were evaluated; also, it was evaluated for in vivo live imaging properties and in vitro skin layer transport and distribution properties.

Results

The mean particle size of Rh-NPs was 96.25 ± 2.26 nm; zeta potential of 15.89 ± 1.97 mV; PDI of 0.120 ± 0.079. Rh-NPs-DMNs had a high needle content of 96.11 ± 1.27% and a tip height of 651.23 ± 1.28 μm, with excellent mechanical properties (fracture force of 299.78 ± 1.74 N). H&E skin tissue staining showed that Rh-NPs-DMNs produced micron-sized mechanical pores approximately 550 μm deep immediately after drug administration, allowing for efficient circulation of the drug; and the results of in vivo imaging showed that Rh-B NPs DMNs had a faster transport rate than Rh-B DMNs, with strong fluorescent signals in both brain (P<0.01) and hippocampus (P<0.05) 48 h after drug administration.

Conclusion

Nanoparticles can prolong blood circulation time and intracerebral retention time and have certain brain-targeting properties due to their excellent physical properties. The use of microneedle technology combined with nanocarriers provides new ideas for delivery systems for the treatment of central neurological diseases.