Impaired cytokine expression, neutrophil infiltration and bacterial clearance in response to urinary tract infection in diabetic mice

Diabetic patients have increased susceptibility to infections, and urinary tract infections (UTI) are the most common type in women with diabetes mellitus. Knowledge of bacterial clearance effectiveness following UTI in diabetics is sparse. In this study, the effects of diabetes on bacterial clearance efficiency and components of the innate immune system in response to UTI in a murine model were investigated. Streptozotocin-induced diabetic and control female C57BL/6J mice were infected with uropathogenic Escherichia coli, and bacterial load, expression of chemokines, and neutrophil infiltration in the bladder over time were investigated. Expression levels of histone deacetylases were also measured to address a potential mechanism underlying the phenotype. Bacterial clearance during UTI was significantly prolonged in diabetic mice relative to controls. Neutrophil infiltration in bladder tissue and urine, and both mRNA and protein expression of chemokines MIP-2, KC, MCP-1 and IL-6 in bladder tissue were diminished at early time points after infection in diabetic mice relative to controls. In addition, mRNA levels of histone deacetylases 1-5 were increased in diabetic mice. This is the first study to show an association of impaired bacterial clearance in diabetic mice with suppression of UTI-induced chemokine expression and neutrophil infiltration in the bladder.