Objective

2

To investigate the possible mechanism of

Buzhong Yulin Decoction

（补中愈淋汤） in the prevention and treatment of recurrent urinary tract infection.

Methods

2

The mouse models of recurrent urinary tract infection were established by uropathogenic Escherichia coli （UPEC） strain UTI89 by bladder perfusion， and the successful mouse models were randomly divided into a model group， an antibiotic group， and a low- and high-dose

Buzhong Yulin Decoction

group， with six mice in each group. In addition， 5 C57BL/6 mice without modelling were taken as blank group. The low- and high-dose

Buzhong Yulin Decoction

groups received 0.1 ml/10 g of decoction by gavage， with concentrations of 1.3 g/ml and 5.2 g/ml， respectively； the antibiotic group received 0.1 ml/10 g of levofloxacin hydrochloride solution with 5 mg/ml by gavage； the blank and model groups received 0.1 ml/10 g of distilled water by gavage. Each group was gavaged once a day for 7 consecutive days. The total number of urine marks， the number of central urine marks， and the total urine volume of the urine marks were observed by the urine marking test； HE staining was used to observe the histopathological changes in the bladder of mice； serum levels of the inflammatory factors interleukin 1β （IL-1β）， interleukin 6 （IL-6） and tumour necrosis factor α （TNF-α） were detected by ELISA； the morphology of the epithelial cells of bladder was observed by scanning electron microscopy； immunofluorescence assay to detect bladder tissue anti-UroPlakin 3A protein level and UPEC bacterial load； the spread plate method to detect urinary bacterial load and bacterial load of bladder epithelial cells； RT-PCR method to

detect Ras-related protein Rab-11A （RAB11A） and Ras-related protein Rab-27B （RAB27B） mRNA level in bladder tissue； immunoblotting to detect microtubule-associated protein 1 light chain3 （LC3） and P62 protein levels in bladder tissue.

Results

2

Compared with the blank group， the bladder epithelial cell layers were lost and showed abnormal morphology in mice of the model group； bladder tissue UroPlakin 3A protein and RAB11A and RAB27B mRNA levels reduced， the total number of urine marks， the number of central urine marks， bladder tissue UPEC bacterial load， urinary bacterial load， bacterial load in bladder epithelial cells， serum IL-1β， IL-6， and TNF-α levels， and LC3 and P62 protein levels in bladder tissue all elevated （

P

＜0.05 or

P

＜0.01）. Compared with the model group， the bladder epithelial cell layers were intact and the morphology of epithelial cells were regular in the low- and high-dose

Buzhong Yulin Decoction

groups； the average surface area of bladder epithelial cells reduced， the levels of UroPlakin 3A protein and RAB11A and RAB27B mRNA in bladder tissues elevated， and total number of urine marks， the number of central urine marks， bladder tissue UPEC bacterial load， urinary bacterial load， bacterial load in bladder epithelial cells， serum IL-1β， IL-6， and TNF-α levels， and P62 protein levels in bladder tissue all reduced （

P

＜0.05 or

P

＜0.01）， but LC3 protein levels showed no statistically significant （

P

＞0.05）. In the antibiotic group， the bladder epithelial cells were partially missing and the morphology of epithelial cells was abnormal. Compared with the antibiotic group， the average surface area of the bladder epithelial cells in the mice increased in the low- and high-dose

Buzhong Yulin Decoction

groups， the bacterial load of the bladder epithelial cells decreased， and the P62 protein level of the bladder tissue decreased （

P

＜0.05）. When comp

aring between the low- and high-dose

Buzhong Yulin Decoction

groups， the differences in each index were not statistically significant （

P

＞0.05）.

Conclusion

2

Buzhong Yulin Decoction

may prevent and treat recurrent urinary tract infection by repairing the bladder mucosal barrier， increasing RAB11A and RAB27B level and enhancing autophagy in bladder tissues， thereby facilitating bacterial clearance from bladder epithelial cells and reducing the bacterial load of bladder epithelial cells.