Impact of Bacterial Vaginosis, as Assessed by Nugent Criteria and Hormonal Status on Glycosidases and Lectin Binding in Cervicovaginal Lavage Samples

Abstract

The objective of this study was to evaluate the impact of hormonal status and bacterial vaginosis (BV) on the glycosidases present and glycosylation changes as assessed by lectin binding to cervicovaginal lavage constituents. Frozen cervicovaginal lavage samples from a completed study examining the impact of reproductive hormones on the physicochemical properties of vaginal fluid were utilized for the present study. In the parent study, 165 women were characterized as having BV, intermediate or normal microflora using the Nugent criteria. The presence of glycosidases in the samples was determined using quantitative 4-methyl-umbelliferone based assays, and glycosylation was assessed using enzyme linked lectin assays (ELLA). Women with BV had elevated sialidase, α-galactosidase, β-galactosidase and α-glucosidase activities compared to intermediate or normal women (P<0.001, 0.003, 0.006 and 0.042 respectively). The amount of sialic acid (Sambucus nigra, P = 0.003) and high mannose (griffithsin, P<0.001) were reduced, as evaluated by lectin binding, in women with BV. When the data were stratified according to hormonal status, α-glucosidase and griffithsin binding were decreased among postmenopausal women (P<0.02) when compared to premenopausal groups. These data suggest that both hormonal status and BV impact the glycosidases and lectin binding sites present in vaginal fluid. The sialidases present at increased levels in women with BV likely reduce the number of sialic acid binding sites. Other enzymes likely reduce griffithsin binding. The alterations in the glycosidase content, high mannose and sialic acid binding sites in the cervicovaginal fluid associated with bacterial vaginosis may impact susceptibility to viruses, such as HIV, that utilize glycans as a portal of entry.

Focusing the diversity of Gardnerella vaginalis through the lens of ecotypes

“…Clade membership of strains was not assessed in the study by Moncla et al, but taken together with our findings, we could reasonably anticipate that strains in some clades might have an enhanced ability to degrade components of vaginal mucus, thus enabling direct contact with epithelial cell surfaces (Wiggins et al, 2001). Alpha-fucosidase has also been suggested as a virulence factor, although Moncla et al (2015) could not demonstrate a significant relationship between alpha-fucosidase activity and BV. These results are particularly interesting in view of the marginal difference in expression that have been identified between BV and non-BV strains in vitro for vaginolysin (Castro et al, 2015).…”

“…Alpha‐fucosidase has also been suggested as a virulence factor, although Moncla et al. () could not demonstrate a significant relationship between alpha‐fucosidase activity and BV. These results are particularly interesting in view of the marginal difference in expression that have been identified between BV and non‐BV strains in vitro for vaginolysin (Castro et al., ).…”

“…Activity of such enzymes may increase susceptibility to infection by thinning the protective layer of vaginal mucus (Briselden, Moncla, Stevens, & Hillier, 1992;Cauci et al, 1993). Moncla et al recently demonstrated that enzymatic activities of four glycosidases present in G. vaginalis-sialidase, alpha-galactosidase, beta-galactosidase and alpha-fucosidase-were positively associated with BV diagnosed based on Nugent scores (Moncla et al, 2015). Clade membership of strains was not assessed in the study by Moncla et al, but taken together with our findings, we could reasonably anticipate that strains in some clades might have an enhanced ability to degrade components of vaginal mucus, thus enabling direct contact with epithelial cell surfaces (Wiggins et al, 2001).…”

Glycan cross-feeding drives mutualism betweenFusobacteriumand the vaginal microbiota

“…Our earlier work showed that Gardnerella vaginalis, an abundant species in BV, secretes sialidase, which hydrolyzes sialic acids from host glycans in the extracellular space, followed by uptake and catabolism Lewis et al, 2013). Consistent with these findings, vaginal mucus secretions of women with BV also have higher levels of free/liberated sialic acid Noecker et al, 2016;Srinivasan et al, 2015), and an overall depletion of total/bound sialic acids Moncla et al, 2015;Wang et al, 2015). Interestingly, not all bacteria that catabolize sialic acids express sialidases.…”

“…At 48 and 24 hours prior to infection, mice underwent intraperitoneal injections of 0.5 mg β-estradiol 17-valerate (Sigma) in 100 µl filter-sterilized sesame oil (Fisher) to synchronize the mice in estrus. Mice were infected with model uropathogenic Escherichia coli strains (UTI89 and CFT073 (Mobley et al, 1990;Mulvey et al, 2001) or mutant derivatives thereof. Strains were cultured statically in lysogeny broth (LB) at 37°C for two consecutive O/N passages.…”