Uncovering Etiological Roles in the Development of Alzheimer’s Disease (AD)
Tuesday, May 26, 2026
10:00 AM-12:00 PM
BIOMED PhD Thesis Defense
Title:
Uncovering Etiological Roles in the Development of Alzheimer’s Disease (AD)
Speaker:
Michiko Thwe, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Advisor:
Garth D. Ehrlich, PhD, FAAAS, FAAM
Professor
Department of Microbiology and Immunology
Department of Otolaryngology-Head and Neck Surgery
College of Medicine
Drexel University
Details:
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, neuroinflammation, amyloid-beta deposition, and tau pathology. Emerging evidence suggests that microbial dysbiosis and chronic host–pathogen interactions may contribute to AD pathogenesis, challenging the long-standing assumption that the human brain is sterile. This dissertation investigates the potential etiological role of microbial communities in Alzheimer’s disease through spatial microbiome profiling, comparative neurobiobank analyses, and strain-level genomic characterization of Cutibacterium acnes.
Using full-length 16S rRNA sequencing, postmortem brain tissues from Alzheimer’s disease and age-matched control cohorts were analyzed to evaluate microbial community composition and determine whether detected microbial signatures represented authentic tissue-associated microbiota or postmortem contamination. Spatial edge-versus-core analyses demonstrated substantial overlap between microbial profiles, supporting the conclusion that the observed bacterial communities were unlikely to arise solely from autopsy-related contamination. Comparative analyses across independent neurobiobanks revealed modest regional and institutional variation while identifying reproducible microbial community structures associated with AD brain tissue. Diversity and ordination analyses further demonstrated overlapping yet distinct microbial patterns related to diagnosis, anatomical location, and cohort origin.
To further investigate the potential contribution of Cutibacterium acnes to neurodegenerative disease, comparative genomics and pan-genome analyses were performed on deep tissue-derived isolates. Whole-genome sequencing demonstrated broad phylogenetic diversity and an open accessory genome enriched with genes associated with adhesion, biofilm formation, oxidative stress response, and virulence-associated functions. Deep tissue isolates were distributed across multiple phylogenetic lineages rather than a single tissue-associated clade, supporting the hypothesis that multiple C. acnes strains may possess the capacity for tissue persistence and inflammatory potential.
These findings contribute to the growing field of neurodegenerative microbiome research and support further investigation into microbial contributions to Alzheimer’s disease pathogenesis and related neuroinflammatory disorders.
Contact Information
Natalia Broz
njb33@drexel.edu