The Oral-Vascular-Neural Axis
Bacterial extracellular vesicles as a candidate oral-systemic disease interface
S. Thaddeus Connelly, DDS, MD, PhD, FACS
San Francisco Veterans Affairs Healthcare System
University of California San Francisco | GengyeUSA | 2026
How to Read This Presentation
This presentation distinguishes established evidence from supported mechanisms and working hypotheses that still require causal testing.
- Periodontitis generates systemic inflammatory and microbial exposure
- Periodontal disease is associated with ASCVD and chronic outcomes
- Periodontal therapy can improve endothelial or inflammatory biomarkers
- P. gingivalis OMVs carry virulence cargo and injure host cells in models
- OMVs can promote endothelial activation and mitochondrial stress
- P. gingivalis is associated with certain cancers and neurodegenerative pathways
- A conserved OMV-driven program contributes across vascular, tumor, and brain disease
- Salivary/blood OMV signals can serve as scalable upstream biomarkers
- Upstream oral intervention can change long-term systemic trajectories
Read this as a disciplined translational hypothesis -- not a proven unifying law.
Why the Mouth-Body Interface Matters
The opportunity is not to collapse diseases into one disease, but to identify shared upstream interfaces worth measuring and testing.
Cardiovascular disease is the leading cause of global mortality
Cancer accounts for nearly 1 in 6 deaths worldwide
Dementia is a major cause of disability and death globally
Even a modest upstream risk signal could matter clinically if it is measurable and modifiable.
Candidate Effector: P. gingivalis Outer Membrane Vesicles
What They Are
20-250 nm bilayer vesicles shed from Gram-negative bacteria. They package concentrated virulence factors and move through tissues and fluids more easily than intact bacteria.
Typical Cargo
- Gingipains
- Heterogeneous LPS / lipid A species
- PPAD and adhesins / fimbrial components
- Nucleic acids
A Working Five-Step Cascade
Useful for organizing experiments; risky if presented as already-proven causality.
Barrier Disruption
Barrier injury is the gatekeeping step that makes distal effects plausible. P. gingivalis cells and OMVs increase endothelial signaling, promote monocyte adhesion, and perturb epithelial integrity.
Mitochondrial Dysfunction
P. gingivalis exposure increases mitochondrial fragmentation and mtROS, lowers membrane potential, and decreases ATP via Drp1-dependent fission in endothelial models.
Phenotypic Reprogramming
OMVs can induce osteogenic calcification in VSMCs, EMT-like programs in oral epithelium, and inflammatory phenotypes in microglia -- avoid over-generalizing across all tissues.
Secondary EV Signals
P. gingivalis infection can alter host EV release and cargo. EVs can propagate pathology in AD models. Mitochondrial transfer occurs in cancer and affects chemoresistance.
Tissue-Level Endpoints
Vascular calcification, cancer progression in oral/GI contexts, and AD-like pathology in animal models are real -- but not identical. Use shared upstream interface, tissue-specific endpoints.
Clinical Implications Justified Today
Be ambitious in screening and collaboration; be conservative in causal claims and treatment promises.
Treat periodontitis as a systemic health issue, not just a local dental problem
Capture periodontal status in cardiometabolic and geriatric histories where relevant
Expect local benefit and some biomarker or endothelial improvement after periodontal therapy
Claiming periodontal disease is a fully validated causal driver of ASCVD, cancer, or AD
Telling patients gingipain inhibition or oral therapy is proven to slow dementia
Presenting the AHA statement as if it resolved the causal question
Bottom Line
Best Current Claim
Oral bacterial EVs are plausible systemic effectors and a tractable upstream biomarker interface -- strong enough to justify measurement, intervention studies, and disciplined translational development now.
Strongest Evidence
Periodontitis-ASCVD association; OMV endothelial effects; mitochondrial stress; selected neural and cancer-related model systems.
Biggest Gaps
Human causality, cargo attribution, prospective biomarker validation, and proof that the proposed cascade is truly conserved across tissues.
Winning Strategy: Prove an upstream signal, show that intervention moves it, and only then claim disease modification. That path is scientifically stronger and commercially more credible.