Biogenic Amines Increase the Odds of Bacterial Vaginosis and Affect the Growth of and Lactic Acid Production by Vaginal Lactobacillus spp

Bacterial vaginosis (BV) is the most common vaginal disorder of reproductive-aged women, yet its etiology remains enigmatic. One clinical symptom of BV, malodor, is linked to the microbial production of biogenic amines (BA). Using targeted liquid chromatography mass spectrometry, we analyzed 149 longitudinally collected vaginal samples to determine the in vivo concentrations of the most common BAs and then assessed their relationship to BV and effect upon the growth kinetics of axenically cultured vaginal Lactobacillus species. Increases in cadaverine, putrescine, and tyramine were associated with greater odds of women transitioning from L. crispatus-dominated vaginal microbiota to microbiota that have a paucity of Lactobacillus spp. and from Nugent scores of 0 to 3 to Nugent scores of 7 to 10, consistent with BV. Exposure to putrescine lengthened the lag time and/or slowed the growth of all vaginal Lactobacillus spp. except L. jensenii 62G. L. iners AB107's lag time was lengthened by cadaverine but reduced in the presence of spermidine and spermine. The growth rate of L. crispatus VPI 3199 was slowed by cadaverine and tyramine, and strain-specific responses to spermine and spermidine were observed. BAs were associated with reduced production of d- and l-lactic acid by vaginal Lactobacillus spp., and this effect was independent of their effect upon Lactobacillus species growth. The exceptions were higher levels of d- and l-lactic acid by two strains of L. crispatus when grown in the presence of spermine. Results of this study provide evidence of a direct impact of common biogenic amines on vaginal Lactobacillus spp.IMPORTANCELactobacillus spp. are credited with providing the primary defense against gynecological conditions, including BV, most notably through the acidification of the vaginal microenvironment, which results from their production of lactic acid. The microbial production of BAs has been hypothesized to play a mechanistic role in diminishing Lactobacillus species-mediated protection, enabling the colonization and outgrowth of diverse anaerobic bacterial species associated with BV. Here, we demonstrate that in vivo increases in the most commonly observed BAs are associated with a loss of Lactobacillus spp. and the development of BV, measured by Nugent score. Further, we show that BAs formed by amino acid decarboxylase enzymes negatively affect the growth of type strains of the most common vaginal Lactobacillus spp. and separately alter their production of lactic acid. These results suggest that BAs destabilize vaginal Lactobacillus spp. and play an important and direct role in diminishing their protection of the vaginal microenvironment.

Abstract A05: Fusobacterium nucleatum and clinicopathologic features of colorectal carcinoma: Results from the ColoCare Cohort

Background: Fusobacterium nucleatum (Fn) plays an active role in normal host physiology and has been associated with colorectal carcinogenesis. To date, the role of Fn in newly diagnosed colorectal cancer patients is unclear. This is the first study to evaluate associations between Fn abundance and clinicopathologic characteristics among neoadjuvant chemotherapy naïve colorectal cancer patients.

Methods: We used presurgery collected fecal stool samples from n=101 prospectively followed, newly diagnosed colorectal cancer patients from the ColoCare Cohort. Quantitative real-time polymerase chain reaction was used to amplify/detect Fn DNA in neoadjuvant chemotherapy-naïve patients, not using antibiotics for at least 1 month. Patients were classified into Fn-high (n=50) or Fn-low (n=51) groups based on median Fn Cycle thresholding (Ct) values (low≤16.72; high>16.72) in fecal DNA. Multivariable regression was utilized to analyze associations between Fn and clinicopathologic characteristics such as tumor stage, tumor site, and tumor grade.

Results: We did not observe statistically significant differences in clinicopathologic or demographic characteristics by Fn abundance groups. Compared to the Fn-low patient group, Fn-high patients were 69% more likely to be diagnosed with stage III colorectal cancer (odds ratio [OR]=1.69, 95% confidence interval [CI] 1.56-15.93, P=0.0067), while there was no difference for stage I or II.

Conclusion: Human gut microbial composition, including Fusobacterium nucleatum abundance, may be linked to colorectal cancer progression.

Citation Format: Patrick Mallea, Christy A. Warby, W. Zac Stephens, Biljana Gigic, Kate Buhrke, Tengda Lin, Juergen Boehm, Sheetal Hardikar, Elisa K. Santori, Petra Schrotz-King, Martin Schneider, Alexis Ulrich, Eric A. Swanson, Adetunji T. Toriola, June Round, Cornelia M. Ulrich, Andreana N. Holowatyj, Jennifer Ose. Fusobacterium nucleatum and clinicopathologic features of colorectal carcinoma: Results from the ColoCare Cohort [abstract]. In: Proceedings of the AACR Special Conference on Modernizing Population Sciences in the Digital Age; 2019 Feb 19-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(9 Suppl):Abstract nr A05.

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

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.