This confirmed the association of MKP1 and c-Fos induction with hypha formation. From these data we conclude that initial recognition of C. Tofacitinib 477600-75-2 albicans yeasts in vaginal ECs is mediated solely by the NF-kB pathway, whereas in oral ECs it is mediated by both NF-kB and MAPK pathways, and both c-Jun and c-Fos transcription factors are activated in vaginal ECs in the late MAPK response to C. albicans whereas only c-Fos is activated in oral ECs, but in both EC types only c-Fos activation is hypha specific. Of major importance is the finding that this MAPK/MKP1/cFos response mechanism is dependent not only on hypha formation but also on fungal burdens and suggests that a threshold level of stimulation is required prior to full activation of the epithelial innate response. This may provide a mechanism by which epithelial tissues can remain quiescent in the presence of low fungal burdens whilst responding specifically and strongly to damage-inducing hyphae as burdens increase. However, of particular interest was the finding that induction of MKP1 and c-Jun phosphorylation and c-Fos was observed only at the highest MOI of 10, one log greater than in oral ECs. This indicates that the responsiveness of vaginal ECs to C. albicans is lower than that of oral ECs and that vaginal ECs may be able to tolerate greater fungal burdens before epithelial activation is initiated. The importance of this difference in fungal burdens to immunity at these two surfaces can be seen more clearly when responses in vivo to candidiasis is considered. In oral mucosa, neutrophils play an important role in clearing or combating infections by C. albicans. However, the situation in vaginal mucosa may be different, where neutropenia does not have a major impact on Candida burdens but does result in reduced inflammation. Importantly, vaginal ECs have a direct fungistatic effect that does not require EC viability, thus controlling the burden of C. albicans without recourse to neutrophils or other immune cells. With the discovery that women with infrequent or recurrent vulvovaginal candidiasis show symptomatic disease at correspondingly lower Candida burdens and that this increased sensitivity is due to EC responsiveness, we can hypothesize that vaginal ECs play a key role in managing Candida burdens at vaginal mucosal surfaces, controlling fungal burden in a passive manner but driving pathological inflammation when they become activated. This inflammation is driven by the recruitment of neutrophils by ECs, which may result in uncontrolled inflammation. Although the initial recognition of C. albicans yeast cells appears to be via NF-kB, this does not necessarily result in immunostimulation as the hyphal deficient strain Defg1/cph1 was unable to induce cytokines after 24 h despite activating NF-kB. This lack of cytokine induction by C. albicans yeast cells is common to oral ECs but is in contrast to myeloid/lymphoid cells where strong cytokine responses are induced by yeast cells. Similar effects have been reported in gut ECs, where both NF-kB and p38 signaling are required for full activation of inflammation in the gut.