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Cited by 21Extracellular vesicles in diseaseOral microbiology and periodontitis researchBarrier Structure and Function Studies

Oral Microbially-Induced Small Extracellular Vesicles Cross the Blood–Brain Barrier

Open access
Elashiry, Mahmoud, Carroll, Angelica, Yuan, Jessie, Liu, Yutao, Hamrick, Mark, Cutler, Christopher W., Wang, Qin, Elsayed, Ranya·2024·International Journal of Molecular Sciences
DOI 10.3390/ijms25084509PMC PMC11049816
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Abstract

Porphyromonas gingivalis (Pg) and its gingipain proteases contribute to Alzheimer’s disease (AD) pathogenesis through yet unclear mechanisms. Cellular secretion of small extracellular vesicles or exosomes (EXO) increases with aging as part of the senescence-associated secretory phenotype (SASP). We have shown that EXO isolated from Pg-infected dendritic cells contain gingipains and other Pg antigens and transmit senescence to bystander gingival cells, inducing alveolar bone loss in mice in vivo. Here, EXO were isolated from the gingiva of mice and humans with/without periodontitis (PD) to determine their ability to penetrate the blood–brain barrier (BBB) in vitro and in vivo. PD was induced by Pg oral gavage for 6 weeks in C57B6 mice. EXO isolated from the gingiva or brain of donor Pg-infected (PD EXO) or control animals (Con EXO) were characterized by NTA, Western blot, and TEM. Gingival PD EXO or Con EXO were labeled and injected into the gingiva of uninfected WT mouse model. EXO biodistribution in brains was tracked by an in vivo imaging system (IVIS) and confocal microscopy. The effect of human PD EXO on BBB integrity and permeability was examined using TEER and FITC dextran assays in a human in vitro 3D model of the BBB. Pg antigens (RGP and Mfa-1) were detected in EXO derived from gingival and brain tissues of donor Pg-infected mice. Orally injected PD EXO from donor mice penetrated the brains of recipient uninfected mice and colocalized with hippocampal microglial cells. IL-1β and IL-6 were expressed in human PD EXO and not in Con EXO. Human PD EXO promoted BBB permeability and penetrated the BBB in vitro. This is the first demonstration that microbial-induced EXO in the oral cavity can disseminate, cross the BBB, and may contribute to AD pathogenesis.

AI snapshot

Written from the paper’s full text.

TL;DR

This study shows that small extracellular vesicles/exosomes induced by *Porphyromonas gingivalis*/periodontitis carry bacterial virulence factors and inflammatory cytokines, can cross the blood–brain barrier, and localize to hippocampal microglia in mice. Human periodontitis-derived exosomes disrupt an in vitro 3D human BBB model, increasing permeability and downregulating tight junction genes.

Key findings

  • PD EXO from gingival and brain tissues of Pg-infected mice contained Pg antigens RGP and Mfa-1; EXO markers CD81, CD9, TSG101, and CD63 were positive, while GRP94 was negative.
  • DiI-labeled PD EXO injected intragingivally into uninfected WT mice (aged 6 months) produced significantly higher brain signal at 2 h than Con EXO; in hippocampus they colocalized with endothelial cells, RGP, Mfa1, and microglial cells, but not astrocytes.
  • Human PD EXO (n = 7 stage III–IV, grade A/B PD; healthy n = 5) expressed IL-1β and IL-6, unlike healthy control EXO. In a human 3D BBB model, PD EXO decreased TEER at 0.5, 4, and 24 h, crossed to the abluminal side, increased FITC-dextran permeability at 4 and 24 h, and downregulated claudin 4 and Zo-1 mRNA in BMECs.

Methods

  • Mouse PD: 4–5 mo male C57BL6 mice received Pg by oral gavage every other day for 6 weeks; controls received 2% CMC. Gingival/brain EXO were isolated and characterized by NTA, Western blot, and TEM/SEM.
  • Human samples: gingival tissues from healthy controls and PD patients under IRB-approved protocols; EXO were isolated. A human 3D BBB model co-cultured human brain endothelial cells, pericytes, and astrocytes; TEER >150 Ω; DiI-labeled EXO, FITC-dextran, and RT-PCR for claudin 4/ZO-1 were used.
  • Biodistribution: DiI-labeled EXO were injected into palatal gingiva (n = 6 mice/group), tracked by IVIS at 2 and 24 h, with ex vivo brain imaging and confocal microscopy. Statistics used one-way or two-way ANOVA with p < 0.05, Tukey’s multiple-comparisons test, mean ± SD, and experiments repeated 3 times.

Limitations

  • Stated: the study lacks an AD mouse model; the human BBB used is an in vitro model that may not reflect the same physiological response in vivo.
  • Evident from the text: human sample size is small and reported inconsistently (Results: n = 7 PD and n = 5 healthy; Methods: n = 4 PD), and the study does not test AD outcomes or causality in vivo.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/ijms25084509

Cites

35 of 35 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

39 of 40 cited sources checked · 12 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    Exosomes utilize two primary routes to traverse the blood-brain barrier: paracellular and transcellular.

    “EXO were found to utilize two primary routes to traverse the BBB: paracellular, which involves tight and adherens junctions, and transcellular, which involves micropinocytosis, receptor, or caveola-mediated endocytosis [30].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [30] Chen, 2016, Elucidation of Exosome Migration Across the Blood–Brain Barrier Model In Vitro, Cell. Mol. Bioeng. source

      In Results and Discussion (page unavailable), the authors report that paracellular diffusion contributed little to exosome crossing of their in vitro BBB model, while transcellular transport accounted for most migration. The paper therefore does not support describing paracellular and transcellular transport as two primary routes used by exosomes. (LLM, conf=0.88)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
  • Premisecitation

    PD exosomes could transmit senescence to gingival immune cells, including dendritic cells and T cells.

    “Our group showed previously that PD EXO could transmit senescence to gingival immune cells, including DCs and Tells [17,19].”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [17] Elsayed, 2021, Porphyromonas gingivalis Provokes Exosome Secretion and Paracrine Immune Senescence in Bystander Dendritic Cells, Front. Cell. Infect. Microbiol. source

      The Discussion (page not provided) reports that exosomes from P. gingivalis-exposed dendritic cells induced senescence in bystander dendritic cells. The Abstract (page not provided) reports impaired CD4+ T-cell proliferation, not transmission of senescence to T cells. The experiments used mouse bone marrow-derived dendritic cells in vitro, so the paper does not establish the claim for gingival immune cells. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
    • cites [19] Elsayed, 2023, Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice, Aging Dis. source
  • Premisecitation

    Breakdown of the blood-brain barrier plays a critical role in the progression of Alzheimer's disease.

    “The breakdown of the blood–brain barrier (BBB) plays a critical role in the progression of AD [29].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [29] Nation, 2019, Blood–brain barrier breakdown is an early biomarker of human cognitive dysfunction, Nat. Med. source

      The Introduction (page unavailable) reports that BBB breakdown develops early in AD and is associated with early cognitive dysfunction, including in people with AD biomarker positivity. It describes neurovascular dysfunction as a possible contributor to decline, but does not establish that BBB breakdown plays a critical causal role in AD progression. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    The blood-brain barrier is highly vulnerable to penetration by exosomes.

    “It is worth noting that the blood–brain barrier (BBB) is highly vulnerable to penetration by EXO [18].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Ridder, 2014, Extracellular vesicle-mediated transfer of genetic information between the hematopoietic system and the brain in response to inflammation, PLOS Biol. source

      In Results (‘EVs Targeting Neurons May Enter the Brain Via the Circulation’; page not provided), bone-marrow extracellular vesicles transiently increased the permeability of an in vitro BBB model. The Discussion describes entry from the circulation as a likely route, not an established general vulnerability of the BBB to exosome penetration. ‘Highly vulnerable’ overstates these qualified findings. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    Pg-induced or periodontitis-associated exosomes transmit senescence to bystander gingival immune cells.

    “We have shown that EXO isolated from Pg-infected dendritic cells contain gingipains and other Pg antigens and transmit senescence to bystander gingival cells, inducing alveolar bone loss in mice in vivo.”
    • Also stated in: § 3. Discussion · plain
      “Our group showed previously that PD EXO could transmit senescence to gingival immune cells, including DCs and Tells [17,19].”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [17] Elsayed, 2021, Porphyromonas gingivalis Provokes Exosome Secretion and Paracrine Immune Senescence in Bystander Dendritic Cells, Front. Cell. Infect. Microbiol. source

      The Introduction and Discussion report that exosomes from P. gingivalis-infected dendritic cells transmit senescence to recipient young dendritic cells in vitro. The study used bone marrow-derived cells, not bystander gingival cells, and identifies the Pg antigen Mfa1 but does not establish that the exosomes contain gingipains. The Discussion says in vivo studies were underway, so the cited paper does not support the sentence’s claim that these exosomes induced alveolar bone loss in mice. Page numbers were not provided in our copy. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
    • cites [19] Elsayed, 2023, Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice, Aging Dis. source

      The Results section reports that exosomes from Pg-infected dendritic cells were taken up by gingival dendritic and T cells in mice, promoted senescence, and increased alveolar bone loss. However, the Discussion explicitly says that the presence of gingipains or other bacterial antigens in those exosomes remains to be determined, so the citing sentence's cargo claim is not supported. Our copy provides no page numbers for these passages. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
    • Rests on an assumption: Exosomes derived from senescent cells can transport molecular cargo that may induce senescence in bystander cells.
    • Rests on an assumption: Dendritic cells in the oral mucosal barrier are vulnerable to Pg infection and senescence induction.
  • Classified as probably not a substantial claim. 14
  • May combine two claims. 14

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Microglial cells are resident housekeeping phagocytes of the central nervous system with crucial functions in injury response, immune defense, and synaptic remodeling.

    “Microglial cells are resident housekeeping phagocytes of the central nervous system that have a crucial function in injury response, immune defense, and synaptic remodeling [26].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [26] Nayak, 2014, Microglia Development and Function, Annu. Rev. Immunol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Cellular senescence has been identified in several age-related diseases.

    “Cellular senescence (CS), a stable cell cycle arrest, has been identified in several age-related diseases [14].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [14] Kumari, 2021, Mechanisms of Cellular Senescence: Cell Cycle Arrest and Senescence Associated Secretory Phenotype, Front. Cell Dev. Biol. source

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Characterization of PD and control mouse exosomes was performed according to MISEV using Western blot, nanoparticle tracking analysis, and transmission electron microscopy.

    “Characterization of PD mice exosomes (PD EXO) or control mice exosomes (Con EXO) was performed according to MISEV [21] using WB, NTA, and TEM.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [21] Witwer, 2018, Minimal information for studies of extracellular vesicles 2018 (MISEV2018): A position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines, J. Extracell. Vesicles source

  • May combine two claims.

    Study design and conductcitation

    The purity of PD exosomes was approximately 99% and there was a lack of significant Pg outer membrane vesicles.

    “The purity of PD EXO (~99%) and lack of significant Pg outer membrane vesicles (OMV) were confirmed as previously described [19].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [19] Elsayed, 2023, Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice, Aging Dis. source

  • May combine two claims.

    Premisecitation

    Exosomes can cross the blood-brain barrier and have a role in transfer of genetic information from peripheral hematopoietic cells and in inducing neuroinflammation in the brain.

    “EXO can cross the BBB and have been shown to have a role in the transfer of genetic information from peripheral hematopoietic cells and to induce neuroinflammation in the brain [18].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Ridder, 2014, Extracellular vesicle-mediated transfer of genetic information between the hematopoietic system and the brain in response to inflammation, PLOS Biol. source

      The Discussion reports that hematopoietic-cell EVs, including exosomes, transfer functional RNA to brain neurons. Its Figure 8 presents crossing the blood–brain barrier as a possible route, not an established one. The Results report that inflammation increases neuronal transfer; they do not show that exosomes induce neuroinflammation. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A growing body of evidence in human and animal studies supports a role of cellular senescence in neurodegeneration and memory loss in Alzheimer's disease.

    “A growing body of evidence in human and animal studies supports a role of cellular senescence in neurodegeneration and memory loss in AD [16].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [16] Liu, R.-M. (2022). Aging, Cellular Senescence, and Alzheimer’s Disease. Int. J. Mol. Sci., 23. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Chronic exposure to cell stressors can induce premature senescence in the young.

    “Chronic exposure to cell stressors can also induce premature senescence in the young [15].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [15] Palacio, 2019, Restored immune cell functions upon clearance of senescence in the irradiated splenic environment, Aging Cell source

      The Introduction says senescent cells can appear after exposure to DNA-damaging agents, and the Results report senescence-associated changes after irradiation of young mice. However, the Methods specify a single radiation dose, not chronic exposure; the paper therefore does not establish the claim's chronic-exposure qualifier. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Removal of senescent microglial cells inhibits neuroinflammation and cognitive impairment.

    “Moreover, removal of senescent microglial cells was shown to inhibit neuroinflammation and cognitive impairment [28].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [28] Ogrodnik, 2021, Whole-body senescent cell clearance alleviates age-related brain inflammation and cognitive impairment in mice, Aging Cell source

      The Abstract reports reduced p16Ink4a in microglia, reduced inflammatory markers, and improved cognition after senescent-cell treatments in aged mice. The claim omits the mouse and aging context and presents removal of senescent microglia as the established cause, whereas the interventions targeted senescent cells more broadly; the Discussion notes uncertainty about how senescence affects brain aging. No page numbers are available in our copy. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    Porphyromonas gingivalis and its gingipain proteases contribute to Alzheimer's disease pathogenesis through yet unclear mechanisms.

    “Porphyromonas gingivalis (Pg) and its gingipain proteases contribute to Alzheimer’s disease (AD) pathogenesis through yet unclear mechanisms.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Dominy, 2019, Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors, Sci. Adv. source

  • May combine two claims.

    Interpretationcitation

    Pg infection induces senescence in gingival tissues of PD mice and increases the release of pathogenic exosomes that carry pathogen-related and SASP molecules to distant bystander brain cells.

    “These data suggest that Pg infection induces senescence in gingival tissues of PD mice [19] and increases the release of pathogenic EXO that carry pathogen-related and SASP molecules to distant bystander brain cells.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [19] Elsayed, 2023, Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice, Aging Dis. source
    • Rests on an assumption: Exosomes derived from senescent cells can transport molecular cargo that may induce senescence in bystander cells.

  • May combine two claims.

    Premisecitation

    Microglial cells maintain tissue homeostasis and keep the extracellular space clean of β-amyloid, thereby preventing Alzheimer's disease.

    “In addition, several studies showed the paramount role of microglial cells in maintaining tissue homeostasis and keeping the extracellular space clean of β-amyloid (Aβ), thereby preventing AD [27].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [27] Hansen, 2018, Microglia in Alzheimer’s disease, J. Cell Biol. source

      The Conclusion says microglia maintain tissue homeostasis and clear extracellular Aβ, thereby preventing AD, but explicitly presents this as a proposed hypothesis. The Introduction describes evidence for protective functions, so the citing sentence overstates the source by saying studies have shown the full prevention claim as fact. (LLM, conf=0.82)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Pg-induced exosomes are enriched with virulence factors from Pg including gingipains, enabling them to disrupt barrier functions of the epithelium and penetrate through interstitial spaces and lymphatics to enter systemic circulation.

    “Moreover, those EXO are enriched with virulence factors from Pg including gingipains, a potent proteolytic enzyme, enabling them to disrupt barrier functions of the epithelium and penetrate through interstitial spaces and lymphatics to find their way into systemic circulation.”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [19] Elsayed, 2023, Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice, Aging Dis. source

      The Discussion says Pg-induced dendritic-cell exosomes express the Pg Mfa1 fimbrial protein and notes that exosomes can travel to distant sites. But it explicitly says the presence of gingipains in these exosomes remains to be determined. It does not establish epithelial-barrier disruption or the proposed route through interstitial spaces and lymphatics into systemic circulation. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites [20] Elashiry, 2020, Dendritic cell derived exosomes loaded with immunoregulatory cargo reprogram local immune responses and inhibit degenerative bone disease in vivo, J. Extracell. Vesicles source

      The Discussion describes immunoregulatory dendritic-cell exosomes persisting at the gingival disease site, while the Methods describe a periodontitis model dependent on endogenous flora. Searches for Pg-induced exosomes, gingipains, epithelial barrier disruption, lymphatic passage, and systemic circulation found no passage addressing the attributed claim. (LLM, conf=0.75)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data

    Exosome shape and expression of the exosomal marker were confirmed by scanning electron microscopy.

    “EXO shape and expression of the exosomal marker were confirmed by SEM (Figure 4B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    IL-1β and IL-6 were expressed in human PD exosomes and not in control exosomes.

    “IL-1β and IL-6 were expressed in human PD EXO and not in Con EXO.”
    • Also stated in: § 2. Results · plain
      “Immunoblot analysis revealed expression of IL-1β and IL-6 in EXO isolated from gingival tissues of PD patients while not being detected in healthy controls (Figure 4C).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    PD exosomes crossed the blood-brain barrier, shown by increased DiI fluorescent signal in the lower compartment compared to control exosomes and vehicle.

    “Moreover, PD EXO could cross the BBB, as shown by an increased DiI fluorescent signal in the lower compartment (abluminal side) of the BBB compared to Con EXO and vehicle (PBS) (Figure 4F).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Exosomes from gingiva and brain of PD and control mice had correct size, shape, and distinct positive markers CD81, CD9, TSG101, CD63 and negative marker GRP94.

    “Analysis revealed the correct size, shape, and distinct positive markers (CD81, CD9, TSG101, CD63) and negative markers (GRP94) of EXO (Figure 1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Exosomes released in human gingival tissues during periodontitis promote brain microvascular endothelial cell dysfunction by degrading tight junction proteins, increasing blood-brain barrier permeability.

    “The human 3D in vitro model of the BBB used in this study showed that EXO released in human gingival tissues during PD promotes BMEC dysfunction by degrading tight junction proteins, increasing BBB permeability.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Disruption in blood–brain barrier integrity is caused by downregulation or derangement of brain microvascular endothelial cell tight junction proteins.

  • May combine two claims.

    Interpretationown data

    Microbial-induced exosomes in the oral cavity can disseminate and cross the blood-brain barrier.

    “This is the first demonstration that microbial-induced EXO in the oral cavity can disseminate, cross the BBB, and may contribute to AD pathogenesis.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: A major knowledge gap exists in how Pg invades the brain and how it may impact overall brain health.
    • Rests on an assumption: The capability of pathogenic exosomes to migrate systemically from gingiva to cross the blood–brain barrier and penetrate brain tissue has not been investigated yet.
    • Rests on an assumption: Definitive evidence for the presence of whole Pg bacterium in brain tissues is lacking.
    • Rests on an assumption: The precise mechanism of microbial invasion of the blood–brain barrier is not clearly understood.

  • Classified as probably not a substantial claim.

    Study design and conductown data

    Human gingival tissues were obtained under institutional review board-approved protocols.

    “Human gingival tissues from healthy controls (Con) (mean age 45 years) and PD patients (mean age 51 years) (n = 4) stage III–IV, grade B/C PD were obtained under institutional review board (IRB)-approved protocols (IRB NET ID: 1169935-21).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All subjects provided informed consent prior to participation in the study.

    “All subjects provided informed consent prior to participation in the study.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The lack of an Alzheimer's disease mouse model is a limitation of the current study.

    “Although the current study aims to determine the link between PD and neurogenerative diseases including AD, the lack of an AD mice model is a limitation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The human blood-brain barrier used is an in vitro model that may not reflect the same physiological response in in vivo settings.

    “In addition, the human BBB used is an in vitro model that may not reflect the same physiological response in the in vivo settings.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Oral microbially-induced exosomes can pass through the blood-brain barrier and can traffic inflammatory molecules and bacterial virulence factors to brain cells.

    “Oral microbially-induced EXO (PD-EXO) can pass through the blood–brain barrier and can traffic inflammatory molecules and bacterial virulence factors to brain cells.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: A major knowledge gap exists in how Pg invades the brain and how it may impact overall brain health.
    • Rests on an assumption: The capability of pathogenic exosomes to migrate systemically from gingiva to cross the blood–brain barrier and penetrate brain tissue has not been investigated yet.
    • Rests on an assumption: Definitive evidence for the presence of whole Pg bacterium in brain tissues is lacking.
    • Rests on an assumption: The precise mechanism of microbial invasion of the blood–brain barrier is not clearly understood.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The Institutional Animal Care and Use Committee of Augusta University approved all experimental procedures under protocol #2022-1073.

    “The Institutional Animal Care and Use Committee (IACUC) of Augusta University (protocol #2022-1073) approved all experimental procedures.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Study design and conductnone given

    A 260/280 RNA ratio of 2.0 was considered adequate for analysis.

    “A ratio of 260/280 of 2.0 was considered adequate for analysis.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    In the human in vitro blood-brain barrier model, TEER readings reaching 150 Ω × cm2 or greater were considered sufficient for further studies.

    “Model TEER readings reaching 150 Ω × cm2 or greater were considered sufficient for further studies.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Experiments were repeated 3 times.

    “experiments were repeated 3 times.”
    Quote in the paperNot a substantial claim
27 of 27

  • The paper relies on this without support.

    A major knowledge gap exists in how Pg invades the brain and how it may impact overall brain health.

    “A major knowledge gap exists in how the Gram-negative anaerobic coccobacillus Pg, invades the brain and how it may impact overall brain health.”

  • The paper relies on this without support.

    The capability of pathogenic exosomes to migrate systemically from gingiva to cross the blood–brain barrier and penetrate brain tissue has not been investigated yet.

    “However, the capability of these pathogenic EXO to migrate systemically from gingiva to cross BBB and penetrate brain tissue has not been investigated yet.”

  • The paper relies on this without support.

    Definitive evidence for the presence of whole Pg bacterium in brain tissues is lacking.

    “however, definitive evidence for the presence of Pg whole bacterium in the brain tissues is lacking and the precise mechanism of microbial invasion of the BBB is not clearly understood.”

  • The paper relies on this without support.

    The precise mechanism of microbial invasion of the blood–brain barrier is not clearly understood.

    “however, definitive evidence for the presence of Pg whole bacterium in the brain tissues is lacking and the precise mechanism of microbial invasion of the BBB is not clearly understood.”

  • The paper relies on this without support.

    Exosomes derived from senescent cells can transport molecular cargo that may induce senescence in bystander cells.

    “In addition, EXO derived from senescent cells can, in turn, transport molecular cargo that may induce senescence in bystander cells.”

  • The paper relies on this without support.

    Dendritic cells in the oral mucosal barrier are vulnerable to Pg infection and senescence induction.

    “Dendritic cells (DC), a highly migratory immune cell that resides in the oral mucosal barrier, are vulnerable to Pg infection and senescence induction.”

  • The paper relies on this without support.

    Disruption in blood–brain barrier integrity is caused by downregulation or derangement of brain microvascular endothelial cell tight junction proteins.

    “This disruption in BBB integrity is caused by the downregulation or derangement of brain microvascular endothelial cells (BMECs) tight junction proteins.”
7 of 7

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Periodontitis grades differ between Results and Methods

    Major

    The Results describe the periodontitis patients as grade A/B, but the Methods describe them as grade B/C.

  • Human sample counts differ between Results and Methods

    Major

    The Results report seven periodontitis patients and five healthy subjects, while the Methods give n = 4 for the human tissue donors without explaining a separate cohort.

2 of 2

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Related

Authors
Elashiry, M., Carroll, A., Yuan, J., Liu, Y., Hamrick, M., Cutler, C. W., Wang, Q., & Elsayed, R.
Affiliations
Augusta University (US)
Corresponding author
Elsayed, Ranya
ORCID
Venue
International Journal of Molecular Sciences
Publisher
MDPI AG
Published
2024-04-20
Volume
25
Issue
8
Pages
4509
ISSN
1422-0067 (ISSN-L)
DOI
10.3390/ijms25084509
PMC
PMC11049816
OpenAlex
W4395000673
Cited by
21
References
35
Citations by year
2026: 11 · 2025: 10
FWCI
2.86
Type
journal article
Language
en
Open access
Licence
Locations
  • International Journal of Molecular Sciences (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • NIH/NIDCR (R01 DE14328, P30EY031631)
  • NIH/NEI (R01 DE14328, P30EY031631)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Extracellular vesicles in disease
  • Health Sciences › Dentistry › Periodontics › Oral microbiology and periodontitis research
  • Life Sciences › Neuroscience › Neurology › Barrier Structure and Function Studies
Keywords
Porphyromonas gingivalis, periodontitis, small extracellular vesicles, exosomes, blood-brain barrier permeability, Alzheimer's disease, gingipains, senescence-associated secretory phenotype, dendritic cells, microglia, hippocampus, IL-1β, interleukin-6
MeSH terms
Extracellular Vesicles, Animals, Blood-Brain Barrier, Female, Gingiva, Humans, Male, Mice, Inbred C57BL, Periodontitis, Bacteroidaceae Infections, Porphyromonas gingivalis, Mice, Exosomes

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-30.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-30.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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