Opportunity Identified To Support Vaginal Microbiome Health

Opportunity Identified To Support Vaginal Microbiome Health ...

The female genital tract is naturally colonized by mixed bacteria called the vaginal microbiome. These communities are often dominated by species such as Lactobacillus crispatus, thus providing important protective functions in genital health. Despite the fact that overgrowth of several other bacterial species is linked to a condition known as bacterial vaginosis (BV), which has increased risk of sexually transmitted diseases, HIV, and in pregnant women premature birth. Current antibiotic-based therapies for BV are inconsistent with

BV recurrence may be that treatment often causes the microbiome to become dominated by a species called Lactobacillus iners instead of by L. crispatus. In a study published this week in Nature Microbiology, researchers at the Harvard University, demonstrated that L. iners has unique nutritional requirements that distinguish it from L. crispatus, thus permitting it to be targeted using novel therapeutic strategies.

L. iners is the most abundant and common vaginal bacterial species in the world, but it is poorly studied because scientists have had difficulties growing it in a laboratory under conditions used to cultivate species like L. crispatus, according to Seth Bloom, the doctor and an instructor in the Infectious Diseases division at Massachusetts General Hospital and Harvard Medical School who led the authors. Bloom and colleagues found that adding the amino acid cysteine to the standard culture media allowed them to grow strains from samples from United States and South African

Upon arrival, researchers studied a new collection of 1,200 vaginal Lactobacillus genomes from over 300 women across the United States. They found that none of the species had the ability to make their own cysteine. This was based on experiments conducted with Ben Woolston, PhD, and Emily Balskus, PhD, at the Harvard Department of Chemistry and Chemical Biology. Upon arrival, the researchers found that all vaginal Lactobacillus species were linked to Lactobacillus-dominant

All vaginal lactobacilli obtain cysteine from their environment, but L. iners'' ability to do so was less limited than other species, according to Bloom. Moreover, when we looked at the genomes, we discovered that all species except L. iners had several systems that were predicted to transport cysteine or its oxidized form, cystine. The researchers therefore investigated the effects of compounds that were known to inhibit cystine uptake, confirming that cystine uptake inhibitors selectively blocked growth of L

During this study, Bloom and Mafunda cultivated mixed bacterial plants including L. iners, L. crispatus, and various BV-associated bacteria in the laboratory. The results showed that the combination allowed L. crispatus to outcompete other species more effectively than the antibiotic alone.

The researchers believe these findings suggest a path towards better treatments. One reason why it was difficult to develop effective BV therapies is that we haven''t had the appropriate tools to investigate the vaginal microbiome in the lab, according to Doug Kwon, MD, PhD, Ragon core member and senior author on the study. Here, developing the appropriate tools to cultivate L. iners in the lab immediately translated into a significant conclusion that would hopefully lead to improved therapies.

The group believes that several key issues remain. It isn''t yet clear how L. iners removes cysteine from its environment, and more powerful inhibitors may need to be developed before the treatment strategy can be adopted. However, the study is a promising step forward for this common but difficult-to-treat condition.

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