Obesity does not simply aggravate AS-associated gut dysbiosis but instead 'redirects it towards a distinct community state, characterized by a Prevotella expansion that consistently opposes the rest of the bacterial community.'
Key Findings
Results
Gut microbial community composition differed significantly across non-obese AS patients, obese AS patients, and non-obese controls.
Shotgun metagenomic sequencing was performed on three groups: non-obese AS patients (AS-NOB, BMI < 30, n = 93), age-sex-matched non-obese controls (Ctrl-NOB, BMI < 30, n = 27), and obese AS patients (AS-OB, BMI ≥ 30, n = 68).
PERMANOVA analysis showed significant community-level differences across all groups (F = 3.23, p = 0.001).
Among all metadata variables examined, obesity had the strongest effect on microbiome structure in AS patients (F = 3.1, p < 0.01).
Results
Obese AS patients demonstrated significantly reduced species richness and evenness compared to non-obese groups.
Alpha diversity metrics showed decreased species richness and evenness in the AS-OB group (p < 0.05).
Reduced alpha diversity in obese AS patients may represent a putative indicator of increased cardiovascular risk.
The reduction in diversity was considered potentially relevant in populations where the Prevotella enterotype or subtype is prevalent.
Results
Obese AS patients exhibited a pathological expansion of Prevotella that consistently opposed the rest of the bacterial community.
Prevotella expansion was identified as the defining taxonomic feature distinguishing the obese AS microbiome profile from the non-obese AS profile.
The Prevotella-dominated community state was characterized as a distinct microbiome configuration rather than a simple aggravation of AS-associated dysbiosis.
Prevotella expansion was described as consistently opposing the rest of the bacterial community in obese AS patients.
The authors describe this as a 'distinct community state' rather than a worsening of the same dysbiotic pattern seen in non-obese AS.
Results
Specific bacterial taxa were identified as markers of the AS microbiome regardless of obesity status.
Increased abundance was detected in Pseudomonadota (formerly Proteobacteria), Bilophila, Dysosmobacter, and Faecalibacterium in AS patients.
These taxa were identified through taxonomic analysis as AS microbiome markers.
Functional analysis complemented taxonomic findings to characterize the distinct community states across groups.
Discussion
Obesity redirects rather than simply amplifies AS-associated gut dysbiosis, producing a qualitatively distinct microbiome profile.
Taxonomic and functional analysis together supported the conclusion that obesity-related dysbiosis in AS is not merely an aggravated version of non-obese AS dysbiosis.
The distinct community state in obese AS patients was dominated by Prevotella expansion opposing the broader bacterial community.
The study included both compositional (taxonomic) and functional (metagenomic) capacity analyses using shotgun sequencing to support this conclusion.
The authors suggest this has implications for populations where the Prevotella enterotype or subtype is prevalent, warranting further investigation.
What This Means
This research suggests that the bacteria living in the gut (the gut microbiome) look quite different in people who have atherosclerosis (hardening and narrowing of the arteries) depending on whether they are also obese. The study compared three groups of people in Kazakhstan using advanced DNA sequencing of gut bacteria: people with atherosclerosis who were not obese (93 participants), people with atherosclerosis who were obese (68 participants), and healthy non-obese controls (27 participants). The researchers found that obesity had the strongest influence on gut microbiome structure among all the factors they measured, and that obese atherosclerosis patients had less diverse gut bacterial communities than the other groups.
Importantly, the study found that obesity does not simply make the gut microbiome imbalances seen in atherosclerosis worse — instead, it appears to create a completely different pattern of imbalance. Obese atherosclerosis patients showed a dramatic overgrowth of a type of bacteria called Prevotella, which seemed to crowd out or conflict with most other bacterial species in the gut. Meanwhile, other bacteria including Proteobacteria, Bilophila, Dysosmobacter, and Faecalibacterium were elevated across atherosclerosis patients regardless of obesity status.
This research suggests that Prevotella overgrowth combined with reduced bacterial diversity could serve as a potential warning sign of higher cardiovascular risk, particularly in populations where Prevotella-type gut microbiomes are already common. Understanding these distinct microbiome patterns in obese versus non-obese atherosclerosis patients could eventually help guide more personalized approaches to monitoring and managing cardiovascular disease, though the authors note that further investigation is needed to confirm these findings and understand their clinical significance.
Issilbayeva A, Vinogradova E, Chulenbayeva L, Kozhakhmetov S, Jarmukhanov Z, Myrzakhmetova G, et al.. (2026). Distinct gut microbiome profiles characterize obese and non-obese patients with atherosclerosis: a metagenomic analysis.. Journal of translational medicine. https://doi.org/10.1186/s12967-026-08739-1