Proteome profiles of vaginal fluids from women affected by bacterial vaginosis and healthy controls: outcomes of rifaximin treatment

Objectives: This study was designed to characterize the proteome of vaginal fluid (VF) from women with bacterial vaginosis (BV) in comparison with that from healthy women, and to evaluate the effect exerted by rifaximin vaginal tablets. Methods: Women with BV (n = 39) and matched healthy controls (n = 41) were included in the study. BV patients were distributed among four groups receiving different doses of rifaximin. Vaginal rinsings were collected at the screening visit from all the participants and at a follow-up visit from BV-affected women. The VF proteome was analysed by tandem mass spectrometry using an Orbitrap mass analyser. Results: A large number of human proteins were differentially expressed in women with BV in comparison with healthy women (n = 118) and in BV-affected women treated with rifaximin (n = 284). In both comparisons, a high proportion of the dysregulated proteins (similar to 20%) were involved in the innate immune response. Twenty-one of 24 proteins increased in abundance in women with BV versus healthy women and 31/59 proteins decreased after rifaximin treatment, suggesting a general reduction of the immune response resulting from the therapy. Major changes in protein abundance were found following treatment with 25 mg of rifaximin once daily for 5 days. Conclusions: BV is associated with a massive change in the VF proteome, mainly regarding the abundance of proteins involved in the innate immune response. Rifaximin at a dosage of 25 mg for 5 days modulated the vaginal proteome, counteracting the alterations associated with the BV condition.