Secreted gingipains from Porphyromonas gingivalis increase permeability in human cerebral microvascular endothelial cells through intracellular degradation of tight junction proteins

Nonaka, Saori; Kadowaki, Tomoko; Nakanishi, Hiroshi

doi:10.1016/j.neuint.2022.105282

Cited by 43 publications

(44 citation statements)

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“…An increasing number of clinical studies have demonstrated the impact of periodontitis on AD, and recent experimental studies clarified the route of transduction of inflammatory signals from periodontitis to the brain. Porphyromonas gingivalis ( Pg ), a major pathogen of chronic periodontitis, has virulence factors including lipopolysaccharide (LPS), cysteine proteases called gingipains and outer membrane vesicles [ 1 , 2 , 3 , 4 ]. Recently, LPS and gingipains, two major virulence factors of Pg , have been detected in the brain tissue of patients with AD on autopsy [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Human β-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L

Inoue

Minatozaki

Katsuta

et al. 2022

IJMS

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Recently, the effects of antibacterial peptides are suggested to have therapeutic potential in Alzheimer’s disease. Furthermore, systemic treatment of Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) induced Alzheimer’s disease-like neuropathological changes in middle-aged mice. Then, we examined whether human β-defensins (hBDs), antimicrobial peptides produced by the oral mucosa and salivary glands, can suppress Pg LPS-induced oxidative and inflammatory responses by microglia. hBD3 (1 μM) significantly suppressed Pg LPS-induced production of nitric oxide and interleukin-6 (IL-6) by MG6 cells, a mouse microglial cell line. hBD3 (1 μM) also significantly inhibited Pg LPS-induced expression of IL-6 by HMC3 cells, a human microglial cell line. In contrast, neither hBD1, hBD2 nor hBD4 failed to inhibit their productions. Furthermore, hBD3 suppressed Pg LPS-induced p65 nuclear translocation through the IκBα degradation. Pg LPS-induced expression of IL-6 was significantly suppressed by E64d, a cysteine protease inhibitor, and CA-074Me, a known specific inhibitor for cathepsin B, but not by pepstatin A, an aspartic protease inhibitor. Interestingly, hBD3 significantly inhibited enzymatic activities of recombinant human cathepsins B and L, lysosomal cysteine proteases, and their intracellular activities in MG6 cells. Therefore, hBD3 suppressed oxidative and inflammatory responses of microglia through the inhibition of cathepsins B and L, which enzymatic activities are necessary for the NF-κB activation.

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Section: Introductionmentioning

confidence: 99%

Human β-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L

Inoue

Minatozaki

Katsuta

et al. 2022

IJMS

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“…OMVs of gut microbiota were also reported to decrease tight junctions of the BBB ( Wei et al., 2020 ). In vitro , Pg OMVs could induce degradation of ZO-1 and occludin in human cerebral microvascular endothelial cell lines, and gingipains in Pg OMVs played a critical role in tight junction degradation ( Nonaka et al., 2022 ).…”

Section: Discussionmentioning

confidence: 99%

“…Many experimental studies conclude that Pg or its virulence factors could induce memory impairment and AD-related pathologies ( Wu et al., 2017 ; Ding et al., 2018 ; Ilievski et al., 2018 ; Zhang et al., 2018 ; Dominy et al., 2019 ; Hayashi et al., 2019 ; Nie et al., 2019 ; Gu et al., 2020 ; Hu et al., 2020 ; Chi et al., 2021 ; Hao et al., 2022 Jiang et al., 2021 ; Qian et al., 2021 ; Su et al., 2021 ; Tang et al., 2021 ). Gingipains are toxic proteases secreted by Pg, it is reported that gingipains are neurotoxic in vivo and in vitro , causing detrimental effects on tau, a protein needed for normal neuronal function ( Dominy et al., 2019 ), and gingipains could degrade tight junction proteins of human cerebral microvascular endothelial cells in vitro ( Nonaka et al., 2022 ), suggesting that gingipains may be responsible for blood–brain barrier (BBB) damage. Lipopolysaccharide (LPS) is another virulence factor of Pg; Pg LPS can induce neuronal inflammation through the TLR4/NF-κB pathway ( Zhang et al., 2018 ) and intracellular Aβ accumulation in neurons in a cathepsin B–dependent manner ( Wu et al., 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Outer membrane vesicles of Porphyromonas gingivalis trigger NLRP3 inflammasome and induce neuroinflammation, tau phosphorylation, and memory dysfunction in mice

Gong

Chen

Mao

et al. 2022

Front. Cell. Infect. Microbiol.

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BackgroundPorphyromonas gingivalis (Pg), the keystone pathogen in chronic periodontitis, is reported to initiate Alzheimer’s disease pathologies in preclinical studies. However, the specific mechanisms and signaling pathways acting on the brain still need to be further explored. Outer membrane vesicles are derived from Gram-negative bacteria and contain many virulence factors of bacteria. We hypothesized that outer membrane vesicles are an important weapon of Porphyromonas gingivalis to initiate Alzheimer’s disease pathologies.MethodsThe outer membrane vesicles of Porphyromonas gingivalis (Pg OMVs, 4 mg/kg) or saline were delivered to 14-month-old mice by oral gavage every other day for eight weeks. Behavioral alterations were assessed by the open field test, Morris water maze, and Y-maze test. Blood–brain barrier permeability, neuroinflammation, tau phosphorylation, and NLRP3 inflammasome-related protein were analyzed.ResultsPg OMVs impaired memory and learning ability of mice and decreased tight junction–related gene expression ZO-1, occludin, claudin-5, and occludin protein expression in the hippocampus. Pg OMVs could be detected in the hippocampus and cortex three days after oral gavage. Furthermore, Pg OMVs activated both astrocytes and microglia and elevated IL-1β, tau phosphorylation on the Thr231 site, and NLRP3 inflammasome–related protein expression in the hippocampus. In in vitro studies, Pg OMV (5 µg/ml) stimulation increased the mRNA and immunofluorescence of NLRP3 in BV2 microglia, which were significantly inhibited by the NLRP3 inhibitor MCC950. In contrast, the tau phosphorylation in N2a neurons was enhanced after treatment with conditioned media from Pg OMV-stimulated microglia, which was attenuated after pretreatment with MCC950.ConclusionsThese results indicate that Pg OMVs prompt memory dysfunction, neuroinflammation, and tau phosphorylation and trigger NLRP3 inflammasome in the brain of middle-aged mice. We propose that Pg OMVs play an important role in activating neuroinflammation in the AD-like pathology triggered by Porphyromonas gingivalis, and NLRP3 inflammasome activation is a possible mechanism.

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“…On the other hand, some components of OMVs may contribute to the "leaky" BBB. LPS caused the "leaky" BBB [30,46] by reducing the number of tight junction proteins, ZO-1 and claudin-5, as well as by disrupting the intercellular adhesion molecules, such as cadherin [47][48][49][50]. OMVs from the periodontal pathogen Porphyromonas gingivalis contain cysteine proteinases, named gingipains, which degrade tight junction proteins and increase BBB permeability in vitro [49,50].…”

Section: Potential Omv Delivery To the Brainmentioning

confidence: 99%

“…LPS caused the "leaky" BBB [30,46] by reducing the number of tight junction proteins, ZO-1 and claudin-5, as well as by disrupting the intercellular adhesion molecules, such as cadherin [47][48][49][50]. OMVs from the periodontal pathogen Porphyromonas gingivalis contain cysteine proteinases, named gingipains, which degrade tight junction proteins and increase BBB permeability in vitro [49,50]. Two in vivo studies showed the presence of OMVs in the brain following peripheral injection of OMVs, suggesting that OMVs can cross the BBB.…”

Section: Potential Omv Delivery To the Brainmentioning

confidence: 99%

Helicobacter pylori infection in the stomach induces neuroinflammation: the potential roles of bacterial outer membrane vesicles in an animal model of Alzheimer’s disease

Park

Tsunoda

2022

Inflamm Regener

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Helicobacter pylori (HP) is a Gram-negative bacterium that colonizes the human stomach chronically. Colonization of HP in the gastric mucosa not only causes gastrointestinal diseases, but also is associated with extra-gastric diseases, such as idiopathic thrombocytopenic purpura and neurological diseases. Among neurological diseases, epidemiological studies have shown that HP infection increases the prevalence of Alzheimer’s disease (AD) and Parkinson’s disease (PD). Since HP does not invade the central nervous system (CNS), it has been considered that systemic immunological changes induced by HP infection may play pathogenic roles in AD and PD. Here, we investigated the effects of HP infection on the CNS in vivo and in vitro. In the CNS, chronically HP-infected mice had microglial activation without HP colonization, although systemic immunological changes were not observed. This led us to explore the possibility that HP-derived outer membrane vesicles (HP-OMVs) could cause neuroinflammation. OMVs are small, spherical bilayer vesicles (20–500 nm) released into the extracellular space from the outer membrane of Gram-negative bacteria; OMVs contain lipopolysaccharide, proteins, peptidoglycan, DNA, and RNA. OMVs have also been shown to activate both innate and acquired immune cells in vitro, and to disrupt the tight junctions of the gastric epithelium (“leaky gut”) as well as cross the blood-brain barrier in vivo. Thus, in theory, OMVs can activate immune responses in the remote organs, including the lymphoid organs and CNS, if only OMVs enter the systemic circulation. From the exosome fraction of sera from HP-infected mice, we detected HP-specific DNA, suggesting the presence of HP-OMVs. We also found that microglia incubated with HP-OMVs in vitro increased the cell proliferation, inflammatory cytokine production, and migration. On the other hand, HP-OMVs suppressed the cell proliferation of neuroblastoma in vitro. Lastly, we found that AD model mice infected with HP had amyloid plaques adjacent to activated microglia and astrocytes in vivo. Based on the literature review and our experimental data, we propose our working hypothesis that OMVs produced in chronic HP infection in the gut induce neuroinflammation in the CNS, explaining the higher prevalence of AD in HP-infected people.

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Secreted gingipains from Porphyromonas gingivalis increase permeability in human cerebral microvascular endothelial cells through intracellular degradation of tight junction proteins

Cited by 43 publications

References 38 publications

Human β-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L

Human β-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L

Outer membrane vesicles of Porphyromonas gingivalis trigger NLRP3 inflammasome and induce neuroinflammation, tau phosphorylation, and memory dysfunction in mice

Helicobacter pylori infection in the stomach induces neuroinflammation: the potential roles of bacterial outer membrane vesicles in an animal model of Alzheimer’s disease

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