The vaginal metabolome and microbiota of cervical HPV-positive and HPV-negative women: a cross-sectional analysis

Abstract

Objective: Characterise the vaginal metabolome of cervical HPV-infected and uninfected women.

Design: Cross-sectional.

Setting: The Center for Health Behavior Research at the University of Maryland School of Public Health.

Sample: Thirty-nine participants, 13 categorised as HPV-negative and 26 as HPV-positive (any genotype; HPV⁺ ), 14 of whom were positive with at least one high-risk HPV strain (hrHPV).

Method: Self-collected mid-vaginal swabs were profiled for bacterial composition by 16S rRNA gene amplicon sequencing, metabolites by both gas and liquid chromatography mass spectrometry, and 37 types of HPV DNA.

Main outcome measures: Metabolite abundances.

Results: Vaginal microbiota clustered into Community State Type (CST) I (Lactobacillus crispatus-dominated), CST III (Lactobacillus iners-dominated), and CST IV (low-Lactobacillus, 'molecular-BV'). HPV⁺ women had higher biogenic amine and phospholipid concentrations compared with HPV^- women after adjustment for CST and cigarette smoking. Metabolomic profiles of HPV⁺ and HPV^- women differed in strata of CST. In CST III, there were higher concentrations of biogenic amines and glycogen-related metabolites in HPV⁺ women than in HPV^- women. In CST IV, there were lower concentrations of glutathione, glycogen, and phospholipid-related metabolites in HPV⁺ participants than in HPV^- participants. Across all CSTs, women with hrHPV strains had lower concentrations of amino acids, lipids, and peptides compared with women who had only low-risk HPV (lrHPV).

Conclusions: The vaginal metabolome of HPV⁺ women differed from HPV^- women in terms of several metabolites, including biogenic amines, glutathione, and lipid-related metabolites. If the temporal relation between increased levels of reduced glutathione and oxidised glutathione and HPV incidence/persistence is confirmed in future studies, anti-oxidant therapies may be considered as a non-surgical HPV control intervention.

Tweetable abstract: Metabolomics study: Vaginal microenvironment of HPV⁺ women may be informative for non-surgical interventions.

Keywords: 16S rRNA gene amplicon sequencing; human papillomavirus; vaginal metabolome; vaginal microbiota.

Figure 1|. Fold changes and associated 95% confidence intervals of significantly different metabolites between HPV+ and HPV− women after adjustment for CST and smoking status.

For each metabolite, the dot represents the fold change calculated from exponentiated model coefficients and the line represents the associated 95% confidence interval,

Figure 2|. Discriminatory metabolites associated with HPV status stratified by CST.

HPV− and HPV+ women within CST-I are compared in the first row (A,B). HPV− and HPV+ women within CST-III are compared in second row (C,D) and HPV− and HPV+ within CST-IV are compared in the third row (E,F). A,C,E show discrimination of groups using partial least squares discriminant analysis. B,D,F show the metabolites most strongly influencing discrimination by the PLS-DA. The variable importance in projection (VIP) score is the weighted sum of squares for the PLS-DA loading with the amount of variation explained by each component taken into account. Asterisks indicate metabolites which are also significant via regression analyses.

Figure 3|

Correlation analysis of the microbiome and metabolome. Spearman’s correlation analysis was conducted using potential microbiome biomarkers of HPV as identified by linear discriminant analysis effect size (LEfSe) and potential metabolite biomarkers identified through multiple linear regression.