The defense mechanism of surfactant protein (SP-A, SP-D) against urinary tract infection

SP-D在正常人膀胱粘膜中有表达，在UPEC感染小鼠膀胱中表达增加。分离的J 96-SP-D复合物表现出对5637细胞（人膀胱细胞系）的细菌粘附和UPEC诱导的细胞毒性的降低。此外，SP-D还能与UPK 1a结合，抑制FimH蛋白受体结合域与UPK 1a的结合。用SP-D预孵育5637细胞，然后洗涤细胞，显著降低了细菌对细胞的粘附和UPEC诱导的细胞损伤。我们得出结论，SP-D保护膀胱尿路上皮细胞免受UPEC感染。

SP-D was expressed in normal human bladder mucosa and its mRNA was increased in the bladder of the UPEC infection model in mice. Isolated J96-SP-D complex exhibited decreased bacterial adherence to 5637 cells, the human bladder cell line, and the UPEC-induced cytotoxicity. In addition, SP-D bound to UPK1a and inhibited the binding of receptor-binding domain of FimH protein to UPK1a. Pre-incubation of the 5637 cells with SP-D and then washing the cells significantly decreased bacterial adherence to the cells and UPEC-induced cell injury. We conclude that SP-D protects the urothelial bladder cells against UPEC infection.