Estrogen receptors in human bladder cells regulate innate cytokine responses to differentially modulate uropathogenic E. coli colonization

Abstract

The bladder epithelial cells elicit robust innate immune responses against urinary tract infections (UTIs) for preventing the bacterial colonization. Physiological fluctuations in circulating estrogen levels in women increase the susceptibility to UTI pathogenesis, often resulting in adverse health outcomes. Dr adhesin bearing Escherichia coli (Dr E. coli) cause recurrent UTIs in menopausal women and acute pyelonephritis in pregnant women. Dr E. coli bind to epithelial cells via host innate immune receptor CD55, under hormonal influence. The role of estrogens or estrogen receptors (ERs) in regulating the innate immune responses in the bladder are poorly understood. In the current study, we investigated the role of ER, ER{beta} and GPR30 in modulating the innate immune responses against Dr E. coli induced UTI using human bladder epithelial carcinoma 5637 cells (HBEC). Both ER and ER{beta} agonist treatment in bladder cells induced a protection against Dr E. coli invasion via upregulation of TNF and downregulation of CD55 and IL10, and these effects were reversed by action of ER and ER{beta} antagoinsts. In contrast, the agonist-mediated activation of GPR30 led to an increased bacterial colonization due to suppression of innate immune factors in the bladder cells, and these effects were reversed by the antagonist-mediated suppression of GPR30. Further, siRNA-mediated ER knockdown in the bladder cells reversed the protection against bacterial invasion observed in the ER positive bladder cells, by modulating the gene expression of TNF, CD55 and IL10, thus confirming the protective role of ER. We demonstrate for the first time a protective role of nuclear ERs, ER and ER{beta} but not of membrane ER, GPR30 against Dr E. coli invasion in HBEC 5637 cells. These findings have many clinical implications and suggest that ERs may serve as potential drug targets towards developing novel therapeutics for regulating local innate immunity and treating UTIs. HighlightsO_LIEstrogen receptor (ER) subtypes regulate the gene expression of innate immune molecules, CD55, TNF and IL10 in human bladder epithelial cells impacting the bacterial colonization by Dr E. coli. C_LIO_LIActivation of nuclear ER subtypes, ER and ER{beta}, upregulate the gene expression of proinflammatory cytokine, TNF, but downregulate the gene expression of anti-inflammatory cytokine, IL10, and Dr E. coli colonization receptor, CD55, thus leading to efficient bacterial clearance in human bladder cells. C_LIO_LIIn contrast, activation of the membrane ER subtype, GPR30, shows opposite effects to ER and ER{beta} that were mediated on TNF, IL10 and CD55 gene expression, thus leading to impaired bacterial clearance of Dr E. coli in human bladder cells. C_LIO_LIER subtypes can serve as potential drug candidates for designing new therapies to boost or modulate the local immunity in the human bladder preventing the establishment of E. coli infections. C_LI