R. M. Boudreau1, J. E. Baker1, A. E. Mahdy1, M. J. Edwards1, E. Gulbins1,2, A. P. Seitz1 1University Of Cincinnati,Department Of Surgery,Cincinnati, OH, USA 2University Of Duisburg-Essen,Department Of Molecular Biology,Essen, NORTH RHINE-WESTPHALIA, Germany
Introduction: Urinary tract infections (UTIs) are a leading cause of infectious disease worldwide and cost the US healthcare system an estimated $1.6 billion annually. The most common predictor for susceptibly to UTI is a history of a previous UTI. Acid ceramidase deacylates ceramide to sphingosine; together with sphingosine, it has been shown to play a critical role in the innate immunity of the respiratory epithelium and skin. We have previously reported finding decreased expression of acid ceramidase in uroepithelial cells of patients with UTIs. In this study, we hypothesized that a murine model of UTI would lead to diminished expression of acid ceramidase compared to uninfected controls.
Methods: Wildtype C57BL/6 mice underwent serial inoculation with 1×106 CFU uropathogenic Escherichia coli (E. coli) via transurethral catheterization at 0 and 24 hours. At time points of 1, 3, and 5 days after the second inoculation, mice were sacrificed and their bladders harvested and fixed in 4% formaldehyde. The bladders were then analyzed by immunohistochemistry with anti-acid ceramidase rabbit IgG and a fluorescent secondary antibody. Imaging was then performed using a scanning laser confocal microscope. Select images then were analyzed with Nikon Elements software and fluorescence intensity per µm2 quantified.
Results: Uroepithelial expression of acid ceramidase, as reflected by fluorescence intensity per µm2, was significantly decreased by 56.4% (p < 0.01) in infected bladders compared to control bladders on day 1 after inoculation. (Figure 1)
Conclusion: UTIs represent a significant financial and clinical burden to the healthcare system, with recurrent UTIs proving exceptionally difficult to treat. We report a novel finding of decreased uroepithelial acid ceramidase expression in a murine model of UTI. Taken together with prior reports on the importance of acid ceramidase in innate immunity, these data suggest a possible etiology for susceptibility to recurrent UTI and offer a potential avenue for the treatment and prevention of UTI.
