Interaction of Gardnerella vaginalis and Vaginolysin with the Apical versus Basolateral Face of a Three-Dimensional Model of Vaginal Epithelium

Abstract

Studies have implicated Gardnerella vaginalis as an important etiological agent in bacterial vaginosis (BV). It produces a cholesterol-dependent cytolysin, vaginolysin (VLY). In this study, we sought to characterize the interaction between vaginal epithelium, G. vaginalis, and VLY using EpiVaginal tissues from MatTek. These tissues are three-dimensional and have distinct apical and basolateral sides, enabling comparison of the effects of G. vaginalis and VLY following exposure to either side. We measured cytotoxicity, cytokine production, and bacterial growth, following apical versus basolateral exposure. G. vaginalis exhibited more-rapid growth in coculture with the tissue model when it was exposed to the apical side. VLY permeabilized cells on the basolateral side of the tissues but failed to permeabilize apical epithelial cells. Cytokine secretion in response to VLY and G. vaginalis also depended on the polarity of exposure. VLY did not cause significant changes in cytokine levels when exposed apically. Apical tissue challenge by G. vaginalis appeared to dampen the inflammatory response, as decreases in granulocyte-macrophage colony-stimulating factor (GM-CSF) (6.6-fold), , and interferon gamma inducible protein 10 kDa (IP-10) (53-fold) and an increase in interleukin-1 receptor antagonist (IL-1ra) (5-fold) were observed. In vivo, G. vaginalis normally colonizes the apical face of the vaginal epithelium. Results from this study suggest that while G. vaginalis may grow on the apical face of the vaginal epithelium, its VLY toxin does not target these cells in this model. This phenomenon could have important implications regarding colonization of the vagina by G. vaginalis and may suggest an explanation for the lack of an overt immune response to this organism.Citation Garcia EM, Kraskauskiene V, Koblinski JE, Jefferson KK. 2019. Interaction of Gardnerella vaginalis and vaginolysin with the apical versus basolateral face of a three-dimensional model of vaginal epithelium. Infect Immun 87:e00646-18.

Sequence Comparison of Vaginolysin from Different Gardnerella Species

“…VLY is toxic to a variety of cell types, including erythrocytes, epithelial cells, and neutrophils [3,4,12]. Interestingly, however, we recently reported that the apical face of a three-dimensional tissue model of human vaginal epithelium is relatively resistant to VLY, and our data also showed that there was reduced expression of CD59 on the apical side [13]. This finding seems to contradict in vivo evidence suggesting that Gardnerella spp.…”

“…We recently reported that in a stratified, polarized model of the human vaginal epithelium, VLY Type 2 cytotoxicity was limited to the basolateral side. Apical (lumenal) cells were resistant to the toxin [13].…”

Prospects of NSAIDs administration as double-edged agents against endometrial cancer and pathological species of the uterine microbiome

“…In addition, VLY induces pro-inflammatory signaling, by IL-8 production in human epithelial cells. 44 , 46 , 47 Bacterial VLY, like most of CDCs, uses cholesterol from the cholesterol-rich membrane for integration and recognizes specifically 3-β-hydroxy group by threonine/leucine pair of cholesterol recognition motif, located in the 1 st loop. 48 Results of Gelber et al 44 showed that VLY binds indirectly to cholesterol, involving hCD59 protein as the receptor.…”

Interaction of Macrophages and Cholesterol-Dependent Cytolysins: The Impact on Immune Response and Cellular Survival

“…Most clinical isolates of G. vaginalis from bacterial vaginosis patients express VLY [20]. VLY promotes IL-1β release from epithelial cells, and more IL-1β is stimulated from bacteria that reach the basolateral surface [293]. The increased cytokine production is due to the increased amount of CD59 expressed on the basolateral surface [293].…”

“…VLY promotes IL-1β release from epithelial cells, and more IL-1β is stimulated from bacteria that reach the basolateral surface [293]. The increased cytokine production is due to the increased amount of CD59 expressed on the basolateral surface [293]. Interestingly, VLY also stimulates microvesicle shedding from the apical surface [294].…”