Study: Several important vaginal metabolites elevated in smokers

Women who smoke cigarettes may be more susceptible to urogenital infections and have more vaginal malodor, according to a cross-sectional study in Scientific Reports. The research points to biogenic amines in the vaginal microbiome caused by smoking as the likely the culprits

The study compared the vaginal metabolomes of 17 smokers and 19 nonsmokers by gas and liquid chromatography mass spectrometry.

Analysis of the 16S rRNA gene populations revealed that samples were clustered into the three most common microbial community state types (CSTs): CST-I (L. crispatus-dominated), CST-III (L. iners-dominated) and CST-IV (low-Lactobacillus).

The investigators identified a total of 607 metabolites, more than previously described for the vaginal microenvironment. Of the metabolites, 12 differed significantly between smokers and nonsmokers.

Women categorized as CST-IV who smoked had substantially higher levels of select biogenic amines (including agmatine, cadaverine, putrescine, tryptamine and tyramine) than did nonsmokers in that category. Increased levels of those amines are known to adversely affect the virulence of infective pathogens and contribute to vaginal malodor.

In contrast, dipeptide levels were lower in smokers.

“Probably most surprising was the finding that the concentrations of several biogenic amines were greater among smokers, particularly among smokers with low relative abundances of vaginal Lactobacillus  species,” says co-author Carl Yeoman, PhD, an assistant professor of microbiology and microbial ecology at Montana State University in Bozeman.

The study was conducted to illuminate the mechanism that causes cigarette smoking to be linked to diagnosis of bacterial vaginosis (BV) and to a loss of Lactobacillus species, a group of bacteria that protects the vagina from infection by producing lactic acid.

With BV, “Lactobacillus species are in low relative abundance and are supplanted by a diverse array of anaerobic bacteria,” Dr. Yeoman told Contemporary OB/GYN.

Co-author Rebecca Brotman, PhD, MPH, an associate professor of epidemiology and public health at the University of Maryland School of Medicine in Baltimore, said that a number of prior studies have shown that cigarette smoking is strongly associated with risk of BV and is often found to have a dose-dependent relationship. “This relationship persists, even after controlling for other known confounders such as sexual behaviors,” Dr. Brotman told Contemporary OB/GYN.

BV is also highly recurrent, “with over 50% of women experiencing a symptomatic relapse within 3 to 12 months following antibiotic therapy,” Dr. Brotman said.

“We employed metabolomics, which is a technique that profiles small (<1 kDa) molecule chemicals, because it provides a snapshot biochemical measure of the interaction between host- and microbial-metabolism and the resulting effector molecules,” Dr. Brotman said.

“We knew from prior studies that nicotine and its metabolite cotinine have been detected in the cervical mucus of smokers,” Dr. Brotman said. “The current study confirmed detection of smoking derivatives in the vaginal samples. However, our understanding of the mechanisms by which smoking affects the vaginal microbiota and the potential role of the biogenic amines is still at the ‘tip of the iceberg.’”

The authors hope that ultimately their research will lead to preventative and therapeutic options to remediate BV and avoid urogenital infections.

Dr. Yeoman said the study adds further motivation for women to quit smoking. “Many women are concerned by vaginal malodor, and a large proportion of women use feminine hygiene products like douches, sprays and powders, to help alleviate the odor,” he noted. “The links between smoking and vaginal malodor may inspire some women to try to quit smoking.”

Overall, the authors’ present and previous studies have demonstrated that smoking is associated with a less optimal vaginal microenvironment, “which is not as protective to women’s health,” Dr. Yeoman said. “Given the importance of the vaginal microbiota to both gynecological and reproductive health, we hope that this information can prompt women to enroll in smoking cessation programs.”