Development of gene expression signatures for murine bladder: Control vs. UTI89

Antimicrobial peptides (AMPs) serve key proposed roles in defending the urinary tract against invading uropathogens, but individual AMPs bearing greatest responsibility for these functions remain largely unknown. We identified RegIIIγ as the most transcriptionally upregulated AMP in bladder transcriptomes following uropathogenic Escherichia coli (UPEC) infection. We confirmed induction of RegIIIγ mRNA during cystitis and pyelonephritis by quantitative RT-PCR. Immunoblotting demonstrates increased bladder and urinary RegIIIγ protein levels following UPEC infection. Immunostaining localizes RegIIIγ protein to urothelial cells of infected bladders and kidneys. Human patients with cystitis and pyelonephritis exhibit increased urine levels of the orthologous HIP/PAP protein. Recombinant RegIIIγ protein does not demonstrate bactericidal activity toward UPEC in vitro, but does kill Staphylococcus saprophyticus in a dose-dependent manner. RegIIIγ knockout and control urinary tracts contain comparable bacterial burden following experimental inoculation of UPEC as well as Gram-positive uropathogens. Thus, while RegIIIγ and HIP/PAP expression occurs in human and murine UTI, their specific functions in the urinary tract remain uncertain. Control (Uninfected) Bladder vs. UTI89 Bladders (Infected 2, 6, and 48hrs). Biological replicates: 4 control replicates, 4 infected replicates per timepoint.