How Does the Cervicovaginal Microbiota Protect Against Chlamydia?

The vaginal microbiota is believed to protect women against Chlamydia trachomatis, and the authors of a new study have determined how that protective mechanism works. According to the findings, the cervicovaginal microbiota modulates host functions to protect against the infection.

To reach this conclusion, the researchers analyzed the way in which different Lactobacillus spp. affect C trachomatis infection in a 3-dimensional cervical epithelium model. To do this, the researchers utilized Lactobacillus spp. that had been identified through a culture-independent metataxonomic analysis of women with C trachomatis.

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The researchers determined that a woman with a vaginal microbiota dominated by L iners may be more susceptible to and less protected against C trachomatis infection. Meanwhile, the supplementation of L iners culture supernatants with d(−) lactic acid can provide protective properties against the infection.

“Lactobacillus spp. that specifically produce d(−) lactic acid were associated with long-term protection against C trachomatis infection, consistent with reduced protection associated with L iners, which does not produce this isoform, and with decreased epithelial cell proliferation, consistent with the observed prolonged protective effect,” the researchers wrote. 

Further, according to the researchers, the interaction between the host and microbiota is greatly impacted by epigenetic modifications involving histone deacetylase-controlled pathways.

“The findings suggest that d(−) lactic acid-producing Lactobacillus spp. modulate vaginal epithelial cell homeostasis by regulating a global transcriptional and functional network that includes epigenetic mechanisms that regulate gene expression, ultimately leading to reduction in cell cycling and protection against C trachomatis infection,” the researchers concluded.

According to the study authors, this understanding of how the cervicovaginal microbiota protects against C trachomatis may aid in the future development of novel microbiome-based therapies for sexually transmitted infections.

—Colleen Murphy

Reference:

Edwards VL, Smith SB, McComb EJ, et al. The cervicovaginal microbiota-host interaction modulates Chlamydia trachomatis infection [published online August 13, 2019]. MBio. doi:10.1128/mBio.01548-19.