OBJECTIVES Recurrent urinary tract infections are associated with uropathogenic Escherichia coli (UPEC) ascending and infecting the urinary tract. Antibiotics provide only symptomatic relief, not prevent recurrence. Clinical evidence suggests that intravesical glycosaminoglycan therapy, such as hyaluronic acid (HA), helps reduce UTI recurrence. This has been investigated here using in vitro systems modelling the urogenital tract tissues. METHODS RT4 bladder cells were preconditioned with high molecular weight HA (> 1500 kDa) at 2 mg mL-1 and challenged with UPEC to analyse barrier protection and bacterial adherence. Untreated and HA-preconditioned VK2 E6/E7 vaginal cells were challenged with E. coli flagellin (50 ng mL-1) to mimic bacterial challenge, and media analysed for lipocalin-2, human β-defensin 2 and interleukin-8 by ELISA. Experiments were repeated after siRNA knockdown of Toll-like receptors 2, 4 and 5, and CD44 to investigate signalling. RESULTS Microscopic analyses showed reduced bacterial adherence and urothelial disruption with HA, suggesting that HA functions as a barrier protecting the epithelium from bacterial infection. Cells treated with HA and flagellin simultaneously produced more of the host antimicrobial peptide LCN2 and pro-inflammatory IL-8 (P < 0.05) compared to the no HA/flagellin challenges. Increased gene expression of DEFB4 (P < 0.05), but not the hBD2 peptide, was observed in the HA/flagellin-challenged cells. CONCLUSION These data suggest that exogenous HA has potential to protect the urogenital epithelia from UPEC infection via a two-pronged approach that involves the physical enhancement of the epithelial barrier and augmentation of its innate immune response.

中文翻译：

---

高分子量透明质酸：预防泌尿生殖道感染的双管齐下的保护剂？

目的 复发性尿路感染与尿路致病性大肠杆菌 (UPEC) 上升并感染尿路有关。抗生素只能缓解症状，不能预防复发。临床证据表明膀胱内糖胺聚糖治疗，例如透明质酸（HA），有助于减少尿路感染复发。这里已经使用体外系统模拟泌尿生殖道组织对此进行了研究。方法 RT4 膀胱细胞用 2 mg mL-1 的高分子量 HA (> 1500 kDa) 预处理，并用 UPEC 激发以分析屏障保护和细菌粘附。用大肠杆菌鞭毛蛋白 (50 ng mL-1) 攻击未经处理和 HA 预处理的 VK2 E6/E7 阴道细胞以模拟细菌攻击，并通过 ELISA 分析培养基中的脂质运载蛋白-2、人 β-防御素 2 和白介素-8。在 siRNA 敲低 Toll 样受体 2、4 和 5 以及 CD44 后重复实验以研究信号传导。结果 显微镜分析显示，HA 可减少细菌粘附和尿路上皮破坏，表明 HA 可作为保护上皮免受细菌感染的屏障。与无HA/鞭毛蛋白处理的细胞相比，用HA和鞭毛蛋白处理的细胞同时产生更多的宿主抗菌肽LCN2和促炎性IL-8 (P < 0.05)。在 HA/鞭毛蛋白攻击的细胞中观察到 DEFB4 的基因表达增加（P < 0.05），但 hBD2 肽的基因表达没有增加。结论 这些数据表明，外源性 HA 有潜力通过双管齐下的方法保护泌尿生殖上皮免受 UPEC 感染，包括物理增强上皮屏障和增强其先天免疫反应。