Characterization a model of prostatic diseases and obstructive voiding induced by sex hormone imbalance in the Wistar and Noble rats.

BACKGROUND: Chronic nonbacterial prostatitis associated with lower urinary tract symptoms (LUTS) is a prevalent condition in men. One potential pathophysiological factor is change in sex hormone, testosterone and estrogen, balance. Inflammation, cancer and obstructive voiding has been induced in the Noble rat strain by altering levels of sex hormones. We evaluated if imbalance of sex hormones could induce comparable diseases also in a less estrogen sensitive Wistar strain rats. METHODS: Subcutaneous testosterone (830 µg/day) and 17ß-estradiol (83 µg/day) hormone pellets were used in male Wistar and Noble strain rats to induce prostatic diseases. The rats were followed for 13 and 18 weeks. Urodynamical measurements were performed at the end of the study under anesthesia. Prostates were collected for further histological analysis. A panel of cytokines were measured from collected serum samples. RESULTS: Noble rats exhibited stromal and glandular inflammation after 13 weeks that progressed into more severe forms after 18 weeks of hormonal treatment. CD68-positive macrophages were observed in the stromal areas and inside the inflamed acini. CD163-positive macrophages were present in the stromal compartment but absent inside inflammatory foci or prostate acini. Thirteen-week hormonal treatment in Noble rats induced obstructive voiding, which progressed to urinary retention after 18-weeks treatment. In the Wistar rats 18-week treatment was comparable to the 13-week-treated Noble rats judged by progression of prostatic inflammation, being also evident for obstructive voiding. Incidence of PIN-like lesions and carcinomas in the periurethal area in Noble rats were high (100%) but lower (57%) and with smaller lesions in Wistar rats. Serum cytokines leptin, CCL5, and VEGF concentrations showed a decrease in the hormone-treated rats compared to placebo-treated rats. CONCLUSIONS: Prostate inflammation and obstructive voiding developed also in the Wistar rats but more slowly than in Noble rats. Male non-castrated Wistar strain rats may thus be suitable to use in studies of pathophysiology and hormone-dependent prostate inflammation and obstructive voiding.

Chronic nonbacterial prostate inflammation in a rat model is associated with changes of gut microbiota that can be modified with a galactoglucomannan-rich hemicellulose extract in the diet.

OBJECTIVES: To investigate dietary effects on the gut microbiota composition in a rat model of nonbacterial chronic prostate inflammation (CPI). MATERIALS AND METHODS: Nonbacterial CPI was induced in the Wistar rat strain with subcutaneous testosterone and 17ß-oestradiol (E2 ) hormone pellets for 18 weeks. Rats with placebo pellets served as healthy controls. Rats with CPI were stratified into two groups, which drank either plain tap water (control group) or tap water supplemented with 2% galactoglucomannan-rich hemicellulose extract (GGM group) from Norway spruce (Picea abies) for 5 weeks. Faecal samples were collected at the end of the study, total DNA was extracted, and the bacterial composition was analysed by 16S rRNA gene sequencing. In addition, faecal samples were assayed for short-chain fatty acid (SCFA) concentrations using gas chromatography. Lipopolysaccharide-binding protein (LBP) was measured in serum samples, as an indirect indicator for bacterial lipopolysaccharide (LPS) load in blood. RESULTS: The microbial biodiversity was significantly different between the treatment groups. In the rats with CPI, there was a significant increase in gut microbial populations Rikenellaceae, Odoribacter, Clostridiaceae, Allobaculum and Peptococcaceae compared with healthy rats. Conversely, levels of Bacteroides uniformis, Lactobacillus and Lachnospiraceae were decreased in rats with CPI. SCFA butyric-, valeric- and caproic-acid concentrations were also decreased in the faecal samples of the rats with CPI. In contrast, acetic acid concentrations and serum LBP were significantly elevated in CPI rats compared with healthy ones. Amongst rats with CPI, treatment with the GGM extract significantly reduced the abundance of Odoribacter and Clostridiaceae levels, and increased the B. uniformis levels compared with CPI rats drinking tap water only. In addition, GGM significantly increased the levels of butyric acid and caproic acid, and reduced the levels of LBP in serum. CONCLUSIONS: Hormone-induced nonbacterial CPI in rats is associated with specific changes in gut microbiota and secondary changes in SCFAs and LPS due to gut microbiota alteration. Our results further suggest that fermentable compounds may have a beneficial effect on CPI.

Galactoglucomannan-rich hemicellulose extract from Norway spruce (Picea abies) exerts beneficial effects on chronic prostatic inflammation and lower urinary tract symptoms in vivo.

Galactoglucomannan (GGM) is the main hemicellulose class in wood of coniferous trees and could be potentially utilized as a possible health-promoting substance for food and pharmaceutical industry. Our aim was to evaluate effects of orally administered GGM-rich extract from Norway spruce in a rat model of chronic prostatitis associated with lower urinary tract symptoms (LUTS). Prostatic inflammation and LUTS was induced in male rats using testosterone and 17ß-estradiol exposure for 18 weeks. Rats were treated with 2% GGM dissolved in drinking water during weeks 13-18. Pelvic pain response, LUT function and histopathological evaluation of the prostate were assessed. The results show that hormonal exposure induced LUTS seen as decreased urine flow rate, increased bladder pressure, voiding times, bladder capacity and residual urine volumes. GGM had positive effects on urodynamical parameters by decreasing the basal bladder pressure, increasing the urine flow rate and volume, reducing the residual volume and increasing micturition intervals. GGM reduced the extent of the hormone exposure-induced prostatic inflammation. Increase of pelvic pain induced by hormone exposure was only slightly affected by GGM treatment. The results suggest that orally administered GGM may have potential usage for improving lower urinary tract function associated with chronic prostatic inflammation.

Stromal activation associated with development of prostate cancer in prostate-targeted fibroblast growth factor 8b transgenic mice.

Expression of fibroblast growth factor 8 (FGF-8) is commonly increased in prostate cancer. Experimental studies have provided evidence that it plays a role in prostate tumorigenesis and tumor progression. To study how increased FGF-8 affects the prostate, we generated and analyzed transgenic (TG) mice expressing FGF-8b under the probasin promoter that targets expression to prostate epithelium. Prostates of the TG mice showed an increased size and changes in stromal and epithelial morphology progressing from atypia and prostatic intraepithelial neoplasia (mouse PIN, mPIN) lesions to tumors with highly variable phenotype bearing features of adenocarcinoma, carcinosarcoma, and sarcoma. The development of mPIN lesions was preceded by formation of activated stroma containing increased proportion of fibroblastic cells, rich vasculature, and inflammation. The association between advancing stromal and epithelial alterations was statistically significant. Microarray analysis and validation with quantitative polymerase chain reaction revealed that expression of osteopontin and connective tissue growth factor was markedly upregulated in TG mouse prostates compared with wild type prostates. Androgen receptor staining was decreased in transformed epithelium and in hypercellular stroma but strongly increased in the sarcoma-like lesions. In conclusion, our data demonstrate that disruption of FGF signaling pathways by increased epithelial production of FGF-8b leads to strongly activated and atypical stroma, which precedes development of mPIN lesions and prostate cancer with mixed features of adenocarcinoma and sarcoma in the prostates of TG mice. The results suggest that increased FGF-8 in human prostate may also contribute to prostate tumorigenesis by stromal activation.

FGF-8b induces growth and rich vascularization in an orthotopic PC-3 model of prostate cancer.

Fibroblast growth factor 8 (FGF-8) is expressed at an increased level in a high proportion of prostate cancers and it is associated with a poor prognosis of the disease. Our aim was to study the effects of FGF-8b on proliferation of PC-3 prostate cancer cells and growth of PC-3 tumors, and to identify FGF-8b-associated molecular targets. Expression of ectopic FGF-8b in PC-3 cells caused a 1.5-fold increase in cell proliferation in vitro and a four- to fivefold increase in the size of subcutaneous and orthotopic prostate tumors in nude mice. Tumors expressing FGF-8b showed a characteristic morphology with a very rich network of capillaries. This was associated with increased spread of the cancer cells to the lungs as measured by RT-qPCR of FGF-8b mRNA. Microarray analyses revealed significantly altered, up- and downregulated, genes in PC-3 cell cultures (169 genes) and in orthotopic PC-3 tumors (61 genes). IPA network analysis of the upregulated genes showed the strongest association with development, cell proliferation (CRIP1, SHC1), angiogenesis (CCL2, DDAH2), bone metastasis (SPP1), cell-to-cell signaling and energy production, and the downregulated genes associated with differentiation (DKK-1, VDR) and cell death (CYCS). The changes in gene expression were confirmed by RT-qPCR. In conclusion, our results demonstrate that FGF-8b increases the growth and angiogenesis of orthotopic prostate tumors. The associated gene expression signature suggests potential mediators for FGF-8b actions on prostate cancer progression and metastasis.