The goal of this observational study, called OMICA (Oral Microbiome in Carotid Atherosclerosis), is to learn how bacteria living in the mouth may influence the development and stability of plaques in the carotid arteries, which supply blood to the brain. Plaque buildup in these arteries can lead to stroke.
Researchers want to understand whether certain oral bacteria are linked to plaque vulnerability, meaning a higher chance that the plaque will rupture and cause a stroke.
The study will include a cohort of adults scheduled for carotid endarterectomy at Semmelweis University. Participants will be enrolled in the Semmelweis University Carotid Biobank project.
The main questions the study aims to answer are:
Do people with more severe gum disease or tooth infection have a higher number of bacteria in their carotid plaques, and are those plaques more likely to rupture?
Are the bacteria found in vulnerable plaques different from those in stable plaques?
Are similar bacteria found in the mouth, gut, and plaques, suggesting that bacteria may travel through the body?
What participants will do:
Have their oral health checked before surgery, including an exam of gum disease and tooth infections.
Provide microbiome samples from the mouth, anus, urine, and carotid plaque (taken during surgery).
Have preoperative photon-counting computed tomography (CT) performed to assess plaque stability and study eligibility.
All samples and imaging data will be analyzed to identify bacterial species and their relationship to plaque type.
The study does not involve any experimental treatment or medication. Participation adds no significant medical risk beyond standard care.
Researchers will compare bacterial patterns between people with vulnerable plaques and those with stable plaques to identify microbial signatures linked to carotid plaque instability.
The results may help create future microbiome-based risk models for detecting people at higher risk of stroke or severe atherosclerosis.
Confirmed internal carotid artery (ICA) stenosis on preoperative photon-counting computed tomography (CTA)
Adults (≥18 years) undergoing carotid endarterectomy at Semmelweis University.
Eligible for surgery based on standard anesthesiologic evaluation.
Willing and able to provide written informed consent for participation and sample collection.
Active systemic infection or current antibiotic therapy within 30 days before surgery.
Immunosuppressive therapy or immunodeficiency disorders.
Inability to undergo MRI (e.g., pacemaker, metallic implants, severe claustrophobia).
Pregnancy or lactation.
Participants will be recruited from patients undergoing carotid endarterectomy at Semmelweis University, Budapest, Hungary, within the framework of the Semmelweis Carotid Plaque Biobank. Eligible individuals are adults with confirmed internal carotid artery stenosis identified by photon-counting CT angiography. Enrollment is consecutive among surgical candidates who provide informed consent. The study population reflects a tertiary vascular surgery center cohort representing both stable and vulnerable plaque phenotypes, as classified by ultrasound, MR, and CTA imaging.
Cohort
Prospective
Sample Collection
Other interventionParticipants undergo preoperative oral health evaluation and the collection of oral, anal, urine, blood, and carotid plaque samples during carotid endarterectomy for microbiome analysis. All samples are fully anonymized and processed within the Semmelweis University Carotid Plaque Biobank (BM/33955-1/2023). No experimental treatments are administered; all activities occur within the framework of biobank-approved surgical and diagnostic procedures.
Identification of Oral and Carotid Plaque Microbiome Associations
Microbiome composition of oral and carotid plaque samples will be analyzed using next-generation sequencing to identify bacterial taxa correlated with plaque vulnerability. Relative abundance and diversity indices will be compared between participants with vulnerable and stable carotid plaques to determine microbial associations linked to plaque instability.
Differences in Microbiome Composition Between Vulnerable and Stable Carotid Plaques
Microbial diversity, relative abundance, and taxonomic composition of carotid plaque samples will be compared between vulnerable and stable plaques using 16S rRNA gene sequencing and bioinformatic analysis. Results will help identify microbial signatures associated with plaque stability or vulnerability.
Identification of Shared Microbial Taxa Across Oral, Anal, Urine, and Carotid Plaque Samples
Microbiome overlap among oral, anal, urine, and carotid plaque samples will be analyzed to detect bacterial species present across multiple body sites, indicating possible systemic dissemination pathways linked to atherosclerotic plaque progression.
Correlation Between Oral Health Status and Carotid Plaque Vulnerability
Clinical periodontal indices (probing depth, attachment loss, and periapical lesion presence) will be correlated with imaging-defined plaque vulnerability scores to evaluate whether oral disease severity predicts plaque instability.
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Semmelweis University Heart and Vascular Center
Lead sponsor
National Research, Development and Innovation Office, Hungary
Collaborator
