Resolution of chronic bacterial-induced prostatic inflammation reverses established fibrosis

Abstract

BACKGROUND. Prostatic inflammation has been suggested to contribute to the etiology of lower urinary tract symptoms by inducing fibrosis. We previously used a well-characterized mouse model of bacterial-induced prostate inflammation to demonstrate that chronic prostatic inflammation induces collagen deposition. Here, we examined stability of the newly synthesized collagen in bacterial-induced prostatic inflammation and the reversibility of fibrosis after resolution of infection and inflammation. METHODS. Uropathogenic Escherichia coli 1677 was instilled transurethrally into adult C3H/HeOuJ male mice to induce chronic prostatic inflammation. Collagen was labeled by 3H-proline administration for 28 days post-inoculation and 3H-hydroxyproline incorporation measured to determine stability of the newly synthesized collagen. Inflammation score was graded using a previously established system and total collagen content was measured by picrosirius red staining quantitation and hydroxyproline content. Resolution of inflammation and reversal of collagen deposition was assessed after treatment with antibiotic enrofloxacin for 2 weeks on day 28 post-inoculation followed by an 8-week recovery period. RESULTS. Decay analysis of incorporated 3H-hydroxyproline revealed the half-life of newly synthesized collagen to be significantly shorter in infected/inflamed prostates than in controls. Treatment with antibiotic enrofloxacin completely eradicated bacterial infection and allowed resolution of inflammation. This was followed by marked attenuation of collagen content and correlation analysis verified a positive association between the resolution of inflammation and the reversal of collagen deposition. CONCLUSIONS. These data demonstrate, for the first time, that inflammation-induced prostatic fibrosis is a reversible process.