Expression analysis of genes in human vaginal VK2 E6/E7 cells after treatment with estrogen and challenge with flagellin

The female menopause, characterised by reduced estrogen associates with an increased risk of recurrent UTIs caused by uropathogenic Escherichia coli (UPEC). Clinically such infections can be countered by topical vaginal estrogen treatment and the aim of this study was to investigate, in vitro, the effects of topical estrogen treatment on vaginal epithelial responses following challenge with E.coli flagellin used to mimic UPEC. Immortalised vaginal epithelial cells (VK2 E6/E7), modelling the vaginal epithelium were treated with either 4nM 17β-estradiol (E) for seven days, 50ng/ml E.coli flagellin (F) for 12h, or 4nM 17β-estradiol plus 50ng/ml flagellin (E + F(12h)). RNA was analysed by microarray gene profiling using the Illumina HumanHT-12 v 4 Expression Beadchip. Following E + F treatments expression of genes encoding host defence molecules including DEFβ4A, DEFB103A, LCN2 as well as those associated with keratinisation e.g. CNFN and SPRR family genes were significantly enhanced (P<0.05) compared to either E or F treatments alone. Mutation of EREs identified in the DEFβ4 gene promoter abolished the augmented gene expression suggesting estrogen functioned directly through a transcriptional regulatory mechanism involving ESR1/2. Ingenuity pathway analyses also suggested the pro-inflammatory cytokine IL-17A to regulate the vaginal host defences during infection. Pre-treating VK2 E6/E7 cells with estrogen (4nM) and challenging with 1L-17A & F (12h) significantly enhanced DEFβ4, DEF103A and S100A7 expression (P<0.05). Origins of vaginal IL-17 in vivo remain unclear, but vaginal biopsy material suggests gd T cells located within the vaginal epithelium. These data suggest that the vaginal antimicrobial response induced by flagellin activation of TLR5 cell signalling is augmented significantly by topical estrogen treatment. Microarray analysis was performed to identify other potential genes regulated by estrogen and to help determine signalling pathways. VK2 cells that were pretreated with 4nM estrogen for seven days followed by 50ng/ml flagellin challenge were analysed by microarray. The 12 and 24 hour samples of control, estrogen pretreatment, flagellin, and estrogen pretreatment plus flagellin challenged VK2 cells were selected for analysis. Three technical replicates of each treatment were analysed, totalling 24 samples. Samples to be analysed were shipped on dry ice to Service XS, The Netherlands, who performed RNA quality analysis and carried out the microarray experiments.