Impact of pH and Mycoplasma hominis endosymbiosis on Trichomonas vaginalis pathogenesis.

Authors

Samira Elikaee, Sandip Kumar Mukherjee, Patricia J Johnson

Published in

Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 36. Pages e2610627123. Sep 08, 2026. Epub Aug 31, 2026.

Abstract

The parasite Trichomonas vaginalis colonizes the human vaginal tract and adheres to and lyses epithelial cells causing an inflammatory infection. The vaginal tract is typically acidic, ranging from pH 3.8 to 5.1; however, pathogenesis studies have previously been conducted on parasites grown at pH 5.9 to 6.2. Here we compared the adherence and cytotoxicity of T. vaginalis grown at pH 5.1 and pH 5.9, identifying changes in the surface proteome that contribute to increased pathogenesis of the parasite at pH 5.1. We show that growth of the parasite at pH 5.1 significantly enhances adherence to and lysis of host cells and that this is strongly amplified by the presence of a common bacterial endosymbiont, Mycoplasma hominis. Quantitative proteomics revealed the upregulation of putative surface proteins, three of which were found to be involved in increased parasite adherence and host cell killing. Mechanistic assays demonstrated that a Ricin B-like protein mediates parasite adherence dependent on host glycosaminoglycans via its carbohydrate-recognition domain, while an EF-hand-like protein is shown to promote Ca²⁺dependent adherence. Ricin B overexpression was found to reprogram host metabolism, activating ERK1/2 and HIF-1α and driving a Warburg-like glycolytic shift with greatly increased lactate release, which may create a nutrient-rich niche that supports parasite persistence and host cell cytotoxicity. These studies demonstrate a coordinated upregulation of multiple adhesins rather than a single factor at pH 5.1 in the presence of M. hominis and explore the mechanisms underlying the interaction of parasite surface proteins with the host cell.

PMID:
42673447
Bibliographic data and abstract were imported from PubMed on 01 Sep 2026.

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