Persistence of an IL-4/IL-13 autocrine loop promotes fibrosis-mediated urinary voiding dysfunction

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PROJECT SUMMARY - PROJECT 3 Lower urinary tract symptoms (LUTS) are a costly and potentially critical medical problem for millions of aging men. This spectrum disorder encompasses symptoms such as weak stream, nocturia, incomplete emptying and intermittent urination, all of which are indicative of lower urinary tract dysfunction (LUTD). Surgical ablation of prostate tissue and medical approaches may improve urinary flow, but such treatments are not effective for all men, can produce adverse effects that result in discontinuation of the therapeutic regimen, and do not abrogate the risk for disease progression. If left untreated or treated ineffectively, LUTD can progress to bladder dysfunction, which can lead to urinary retention, recurrent UTI, bladder calculi, and, eventually, renal impairment. Work accomplished by the Macoska laboratory and this Center have shown that collagen accumulation around the prostatic urethra consistent with tissue fibrosis is an untreated pathobiology contributing to LUTD. The overarching goal of the O’Brien Center for Benign Urology Research is to identify mechanisms that result in lower urinary tract dysfunction and prostate-related lower urinary tract symptoms (LUTS). New evidence (presented in this application) indicates heterogeneity among peri-urethral collagen-producing cells as well as inflammatory cells within the prostatic microenvironment. Inflammatory cells secrete a medley of pro-fibrotic proteins into the prostatic microenvironment. Among these proteins, IL-4 and IL-13 are of particular interest because they share a common signaling axis which, as shown here for the first time, establishes and perpetuates an autocrine loop that activates JAK/STAT signaling to promote the expression and maintenance of IL-4, IL-13, their cognate receptors, regulatory transcription factors, and ECM components, even in the absence of inflammatory cells. Based on preliminary data presented here we hypothesize that some peri-urethral stromal cell populations establish an IL-4/IL-13 axis that self-perpetuates, induces myofibroblast phenoconversion and survival, and upregulates collagen accumulation, thereby promoting consequent urinary voiding dysfunction. To test this hypothesis, Project 3 will: 1) Determine whether signaling through the IL-4 receptor creates a STAT6- and GATA-3-mediated positive feedback loop; 2) Elucidate the mechanisms through which the IL-4/IL-13 axis promotes myofibroblast phenoconversion and concordant collagen expression; 3) Determine whether IL-4 pathologically represses myofibroblast apoptosis and thereby promotes myofibroblast survival, and 4) Test whether the IL-4/IL-13 signaling axis promotes lower urinary tract fibrosis and urinary voiding dysfunction in vivo. The results of these preclinical studies will elucidate previously unknown interleukin-mediated molecular and cellular mechanisms that promote lower urinary tract fibrosis and dysfunction. Using JAK/STAT inhibitors to therapeutically target this potentially self-perpetuating mechanism may ‘break the cycle’ and successfully treat recalcitrant peri-urethral prostatic fibrosis contributing to LUTD development and progression.