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 ERα, ERβ and GPR30 in modulating the innate immune responses against Dr E. coli induced UTI using human bladder epithelial carcinoma 5637 cells (HBEC). Both ERα and ERβ agonist treatment in bladder cells induced a protection against Dr E. coli invasion via upregulation of TNFα and downregulation of CD55 and IL10, and these effects were reversed by action of ERα and ERβ 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 ERα knockdown in the bladder cells reversed the protection against bacterial invasion observed in the ERα positive bladder cells, by modulating the gene expression of TNFα, CD55 and IL10, thus confirming the protective role of ERα. We demonstrate for the first time a protective role of nuclear ERs, ERα and ERβ 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.

膀胱上皮细胞引发针对尿路感染 (UTI) 的强大先天免疫反应，以防止细菌定植。女性循环雌激素水平的生理波动增加了对 UTI 发病机制的易感性，通常会导致不良的健康结果。带有大肠杆菌的粘附素博士(Dr E. coli ) 会导致更年期妇女复发性尿路感染和孕妇急性肾盂肾炎。大肠杆菌博士在激素的影响下，通过宿主先天免疫受体 CD55 与上皮细胞结合。雌激素或雌激素受体 (ER) 在调节膀胱先天免疫反应中的作用知之甚少。在目前的研究中，我们使用人膀胱上皮癌 5637 细胞 (HBEC)研究了 ERα、ERβ 和 GPR30 在调节针对大肠杆菌诱导的 UTI 的先天免疫反应中的作用。膀胱细胞中的 ERα 和 ERβ 激动剂治疗均诱导了对大肠杆菌的保护作用通过上调 TNFα 和下调 CD55 和 IL10 进行侵袭，这些作用被 ERα 和 ERβ 拮抗剂的作用逆转。相比之下，激动剂介导的 GPR30 激活由于抑制了膀胱细胞中的先天免疫因子而导致细菌定植增加，而这些作用被拮抗剂介导的 GPR30 抑制所逆转。此外，通过调节 TNFα、CD55 和 IL10 的基因表达，siRNA 介导的膀胱细胞中的 ERα 敲低逆转了在 ERα 阳性膀胱细胞中观察到的对细菌侵袭的保护作用，从而证实了 ERα 的保护作用。我们首次证明了核 ER、ERα 和 ERβ 而不是膜 ER、GPR30 对大肠杆菌博士的保护作用侵袭 HBEC 5637 细胞。这些发现具有许多临床意义，并表明 ER 可作为潜在的药物靶点，用于开发用于调节局部先天免疫和治疗 UTI 的新疗法。