Importance of Microbiomes in vaginas (Introduction)

by David Turell @, Thursday, November 30, 2023, 17:56 (143 days ago)

Can cause vaginosis:

"Editor’s summary
During bacterial vaginosis (BV), an overgrowth of bacteria resides on affected epithelial surfaces, which are prone to increased shedding of cells. Agarwal et al. surveyed the glycans (carbohydrates) covering vaginal epithelial cells in human BV and found depletion of sialic acid residues, resulting in overall diminished protective glycocalyx. Treatment of healthy vaginal epithelial cells with recombinant Gardnerella sialidases recapitulated BV-like desialyated glycans and altered epithelial cell gene expression pathways regulating cell death, differentiation, and inflammatory responses. This work suggests that the action of bacterial sialidases on vaginal surfaces may underlie the aberrant epithelial pathophysiology observed in BV."'Abstract
Epithelial cells are covered in carbohydrates (glycans). This glycan coat or “glycocalyx” interfaces directly with microbes, providing a protective barrier against potential pathogens. Bacterial vaginosis (BV) is a condition associated with adverse health outcomes in which bacteria reside in direct proximity to the vaginal epithelium. Some of these bacteria, including Gardnerella, produce glycosyl hydrolase enzymes. However, glycans of the human vaginal epithelial surface have not been studied in detail. Here, we elucidate key characteristics of the “normal” vaginal epithelial glycan landscape and analyze the impact of resident microbes on the surface glycocalyx. In human BV, glycocalyx staining was visibly diminished in electron micrographs compared to controls. Biochemical and mass spectrometric analysis showed that, compared to normal vaginal epithelial cells, BV cells were depleted of sialylated N- and O-glycans, with underlying galactose residues exposed on the surface. Treatment of primary epithelial cells from BV-negative women with recombinant Gardnerella sialidases generated BV-like glycan phenotypes. Exposure of cultured VK2 vaginal epithelial cells to recombinant Gardnerella sialidase led to desialylation of glycans and induction of pathways regulating cell death, differentiation, and inflammatory responses. These data provide evidence that vaginal epithelial cells exhibit an altered glycan landscape in BV and suggest that BV-associated glycosidic enzymes may lead to changes in epithelial gene transcription that promote cell turnover and regulate responses toward the resident microbiome."

A simple explanation:

According to a new study published in Science Translational Medicine, vaginosis causes a breakdown of glycans—carbohydrates that coat the surface of epithelial cells lining the vagina. Glycans normally provide a protective barrier against infection, but they’re also an attractive meal for hungry microbes. Certain species of vaginosis-associated bacteria release enzymes called sialidases, which dismantle glycans and allow the vaginal microbiome to wreak havoc in the epithelium.

These findings could inform the development of more effective, long-term treatments for vaginosis, the study authors write. Folks with vaginas should also steer clear of scented products and douching, which can throw the vaginal microbiome out of whack.

Comment: the vaginal microbiome normally maintains a healthy vagina. But like any free to change bacterial system it can go wrong and cause trouble. This is a theodicy view: bacteria are so necessary for a healthy life, we must accept bacterial mistakes in action, as an acceptable tradeoff.

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