Expression and Antimicrobial Function of Beta-Defensin 1 in the Lower Urinary Tract
Expression and Antimicrobial Function of Beta-Defensin 1 in the Lower Urinary Tract
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DOI：
10.1371/journal.pone.0077714
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发表时间：
2013-10-21
期刊：
影响因子：
3.7
通讯作者：
McHugh, Kirk M.
中科院分区：
文献类型：
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作者：
Becknell, Brian;Spencer, John David;McHugh, Kirk M.
β防御素(BDS)是一种阳离子多肽，具有抗菌活性，可保护皮肤、胃肠道和呼吸道等上皮表面。然而，BD在尿路中的表达和功能尚不完全清楚。本研究旨在探讨β防御素-1(BD-1)在下尿路中的表达、膀胱炎的调节作用以及体内对尿路致病性大肠杆菌(UPEC)的抗菌活性。人DEFB1和同源小鼠Defb1 mRNA在膀胱和输尿管匀浆中均可检测到，人BD-1蛋白定位于尿路上皮细胞。为了确定BD-1与体内下尿路防御的相关性，我们评估了Defb1基因敲除(Defb1(-/-))小鼠对UPEC的清除。在经尿道接种UPEC后6、18和48h，Defb1(-/-)和野生型C57BL/6小鼠膀胱和肾脏的细菌载量无显著差异。在野生型小鼠中，膀胱Defb1基因的水平在感染后2小时就下降了，并在6小时后达到最低点。逆转录-聚合酶链式反应检测到Defb3和Defb14在小鼠膀胱和输尿管中的表达，它们分别编码Mbd-3和Mbd-14蛋白。UPEC感染后，膀胱尿路上皮细胞表达Mbd-14蛋白，Mbd-3和Mbd-14在体外对UPEC均表现出剂量依赖性杀菌活性。因此，虽然Mbd-1缺乏不会改变体内膀胱UPEC的负荷，但我们已经确定Mbd-3和Mbd-14是下尿路粘膜免疫的潜在介质。
Beta defensins (BDs) are cationic peptides with antimicrobial activity that defend epithelial surfaces including the skin, gastrointestinal, and respiratory tracts. However, BD expression and function in the urinary tract are incompletely characterized. The purpose of this study was to describe Beta Defensin-1 (BD-1) expression in the lower urinary tract, regulation by cystitis, and antimicrobial activity toward uropathogenic Escherichia coli (UPEC) in vivo. Human DEFB1 and orthologous mouse Defb1 mRNA are detectable in bladder and ureter homogenates, and human BD-1 protein localizes to the urothelium. To determine the relevance of BD-1 to lower urinary tract defense in vivo, we evaluated clearance of UPEC by Defb1 knockout (Defb1(-/-)) mice. At 6, 18, and 48 hours following transurethral UPEC inoculation, no significant differences were observed in bacterial burden in bladders or kidneys of Defb1(-/-) and wild type C57BL/6 mice. In wild type mice, bladder Defb1 mRNA levels decreased as early as two hours post-infection and reached a nadir by six hours. RT-PCR profiling of BDs identified expression of Defb3 and Defb14 mRNA in murine bladder and ureter, which encode for mBD-3 and mBD-14 protein, respectively. MBD-14 protein expression was observed in bladder urothelium following UPEC infection, and both mBD-3 and mBD-14 displayed dose-dependent bactericidal activity toward UPEC in vitro. Thus, whereas mBD-1 deficiency does not alter bladder UPEC burden in vivo, we have identified mBD-3 and mBD-14 as potential mediators of mucosal immunity in the lower urinary tract.