Innate immunity of surfactant protein A and D in urinary tract infection with uropathogenic Escherichia coli / 中华肾脏病杂志

ABSTRACT

Objective To investigate the role of surfactant protein (SP)-A and SP-D in urinary tract infection mouse model,and evaluate the effects of SP-A and SP-D absence on urinary tract infection.Methods SP-A and SP-D double knockout (SP-A/D KO) mice were made.SP-A/D KO and wild-type (WT) C57BL/6 female mice were used for this study.The expression of SP-A and SP-D in kidney was detected by immunohistochemistry (IHC).The levels of p-p38 and p38 protein in kidneys were measured by Western blotting.Uropathogenic Escherichia coli or buffer was delivered into the bladder of female mice.At 24 and 48 h after inoculation,CFU of Escherichia coli in the kidney and urine of the treated and control mice were measured.Histological,cellular and molecular analysis were performed by several methods of H/E staining,IHC and Western blotting.The effects of SP-A and SP-D on bacterial growth were studied in vitro.Results SP-A and SP-D in kidney were located in the proximal tubules and collecting tubules.Compared with WT mice,infected SP-A/D KO mice with UPEC had higher CFU in kidneys and urine at 24 h and 48 h,increased inflammatory cells infiltration in kidneys (P＜0.05).Compared with WT mice,SP-A/D KO mice had higher p38 MAPK phosphorylation levels in kidneys (P ＜ 0.05).Growth of Escherichia coli was greatly inhibited by both SP-A and SP-D (P＜0.05).Conclusions Both SP-A and SP-D are expressed in kidney.SP-A and SP-D can attenuate UTI induced by UPEC which may be through inhibiting bacterial growth and modulating renal inflammation.