Dysbiosis of the Saliva Microbiome in Patients With Polycystic Ovary Syndrome Original paper

What was studied

This study examined dysbiosis of the saliva microbiome in polycystic ovary syndrome (PCOS), with emphasis on how microbiota behavior—including diurnal oscillation—differs between affected and healthy women. The focus keyphrase saliva microbiome in PCOS is central here because the investigators explored microbial signatures, taxonomic shifts, and predicted functional changes across four time points over 24 hours. Using 16S rRNA gene sequencing, the researchers mapped salivary and fecal bacterial communities to determine whether PCOS alters microbial diversity, abundance, rhythmicity, and pathway-level characteristics. Their working hypothesis was that circadian oscillations known to occur in healthy salivary microbiota are disrupted in PCOS, which could contribute to local and systemic disease risk.

Who was studied

The cohort included 10 women with PCOS diagnosed by Rotterdam criteria and 10 healthy controls, ages 18–45, all of whom followed standardized dietary guidelines and avoided antibiotics, probiotics, smoking, alcohol, and oral disease that might confound oral microbial signatures. Four saliva samples (ZT0, ZT6, ZT12, ZT18) and one fecal sample per participant were collected under controlled inpatient conditions. The groups were comparable in age and BMI, although PCOS participants exhibited characteristic hormonal alterations, including higher total testosterone and LH/FSH ratios.

Most important findings

PCOS markedly altered the saliva microbiome at every time point. Alpha diversity was significantly reduced at ZT0, while beta-diversity analyses showed distinct clustering between PCOS and controls at ZT0 and ZT18. Across pages 3–5, figures show consistent enrichment of the phylum Fusobacteria and genus Fusobacterium in PCOS saliva at all time points, a microbe linked to inflammation, periodontal disease, metabolic dysfunction, and obesity. LEfSe analysis revealed decreased Actinobacteria and Leptotrichia at multiple time points, alongside gains in taxa such as Gracilibacteria and Clostridiales, depending on the sampling period. These patterns suggest microbial instability, loss of beneficial commensals, and potential overrepresentation of inflammatory contributors. Functional predictions showed recurring upregulation of methane metabolism and downregulation of chaperones, folding catalysts, membrane structural molecules, and secretion systems—changes suggesting impaired microbial protein handling and increased fermentation potential. Several pathways fluctuated rhythmically in healthy controls but not in PCOS, supporting disrupted microbial chronobiology. Diurnal oscillation analysis revealed that taxa such as Proteobacteria, Bacteroidetes, Actinobacteria, Lactobacillales, Prevotellaceae, and Bacteroidales displayed significant rhythmicity in controls but largely lost rhythmic patterns in PCOS. Fecal microbiota, by contrast, showed no consistent PCOS-specific signature, underscoring compartment-specific dysbiosis.

Key implications

Disrupted diurnal rhythm of salivary microbiota in PCOS suggests a chronobiological dimension to disease pathophysiology. Increased Fusobacteria and reduced beneficial taxa may contribute to chronic inflammation, periodontal disease risk, and metabolic dysfunction. The findings highlight the relevance of oral microbiome assessment—and timing of sampling—for understanding systemic features of PCOS and refining microbiome-based clinical tools.

Citation

Li N, Li Y, Qian C, et al. Dysbiosis of the saliva microbiome in patients with polycystic ovary syndrome.Front Cell Infect Microbiol. 2021;10:624504. doi:10.3389/fcimb.2020.624504