New Research Identifies How Microbiome Can Increase Risk or Protection Against Sexually Transmitted Infections (STIs)

BALTIMORE, Aug. 13, 2019 /PRNewswire/ -- New research, published today in the flagship journal of the American Society for Microbiology, is the first to identify a specific mechanism by which keystone species of bacteria in the vaginal microbiome affect a woman's susceptibility to sexually transmitted infections.

The research is timely amidst a rising number of sexually transmitted infections worldwide. In the United States alone, new cases rose sharply for the fourth consecutive year to a record high of 2.3 million new infections according to the Centers for Disease Control and Prevention (CDC). More than 70 percent of those infections were chlamydia, which is particularly challenging to study as the pathogen, Chlamydia trachomatis, hides inside cells and avoids detection by host defenses.

Building on Dr. Ravel's previous breakthrough work which showed the vaginal microbiome can alter the mucus layer to 'trap' HIV, this new research provides the most comprehensive evidence to date that certain types of Lactobacillus exert a permissive or preventive influence upon sexually transmitted infection risk, especially chlamydia.

The vaginal microbiome, defined as the community of microbes within the vagina, is critical to female reproductive and urogenital health, including protection against bacterial vaginosis, urinary tract infection, odor, Candida overgrowth, and even infertility. While the vaginal microbiome's role in sexually transmitted infections has been hypothesized, the causal relationship had not been established until now.

"Prior to this study, it was unclear why some women were more resistant to infection than others," said Dr. Ravel, LUCA Biologics co-founder, Professor of Microbiology and Immunology, the Institute for Genome Sciences (IGS) at the University of Maryland School of Medicine, and Principal Investigator for this research. "Our novel research reveals a mechanistic and functional relationship between the human host and the vaginal microbiome to increase resistance or susceptibility to this infection."

The results of this new research now provide a clear rationale for the use of live biotherapeutics to decrease the risk of infection and prevent reinfection when treating with antibiotics. "We will now be able to leverage this data to identify women at risk of infections, but more importantly, to develop improved strategies to restore protection when it is lacking. Unlike our genes, the vaginal microbiome can be modulated to increase protection against chlamydia, but also against other sexually transmitted infections, including HIV," stated Dr. Ravel.

Modulating the Vaginal Microbiome to Prevent Infection

Previous work by the group has shown that five major vaginal microbiome 'types' exist, four of which are dominated by a different species of Lactobacillus. In this study, the researchers show that after antibiotic treatment for chlamydia, women were more likely to have a vaginal microbiome with Lactobacillus iners, one of the four dominant species. Despite producing lactic acid, L. iners did not protect human cells effectively against chlamydial infection, while another species, Lactobacillus crispatus, was protective.

The most notable difference between the protective and vulnerable vaginal microbiome species was the production of D-lactic acid, which L. iners is unable to synthesize. According to the researchers, just a brief 30 minute exposure to D-lactic acid gives the vaginal mucosa up to 48 hours of protection. The most surprising finding is that the vaginal microbiome does not affect the pathogen directly, but rather predisposes cells in the vaginal epithelium and cervix to resist infection through down-regulating cell cycling.The newly discovered mechanism reveals a critical element in the cross-talk between the microbiome and vaginal epithelium.

"Taken as a whole, these findings support the need to develop adjunct therapy, such as the use of live biotherapeutics that contain beneficial Lactobacillus strains to foster a protective vaginal environment and reduce the risk for infection," noted Dr. Ravel. "This research sheds new light on the outsized role played by the vaginal microbiome in protecting women from chlamydia and other STIs. When it comes to chlamydia, it's now clear that current antibiotic treatment on its own is insufficient. Instead, we need to offer women a blended approach of antibiotics and keystone beneficial bacteria which stabilize the vaginal microbiome to effectively combat C. trachomatis, both in the near term and in the future."

This study is published just after Dr. Ravel's recent launch of LUCA Biologics, a new company developing live biotherapeutics to address widespread, unmet medical needs in women's health.

https://doi.org/10.1128/mBio.01548-19

This research was supported by the National Institutes of Health (NIH) under award numbers U19A1084044 and UH2A1083264.

About LUCA Biologics

LUCA Biologics is a biotechnology company developing a new class of living medicines targeting the vaginal microbiome to impact reproductive and urogenital health. Emerging from the lab of Dr. Jacques Ravel, a leading scientist on the NIH's Human Microbiome Project, the company has built a metagenomic and metatranscriptomic platform to identify and validate strains to modulate the vaginal and urogenital microbiome. Luca.bio

Contact:
Jordyn Lee
[email protected] 

SOURCE LUCA Biologics

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