A uropathogenic E. coli UTI89 model of prostatic inflammation and collagen accumulation for use in studying aberrant collagen production in the prostate

Histologic inflammation and collagen content are not positively correlated in human BPH

INTRODUCTION

Recent clinical studies have implicated prostate inflammation and fibrosis in the development of bladder outlet obstruction and lower urinary tract symptoms (LUTS). Studies utilizing rodent models, including work in our laboratory, have shown prostate fibrosis to occur as a consequence of inflammation. However, the relationship between collagen content and inflammation in human tissue samples obtained from surgical treatment of benign prostatic hypererplasia (BPH)/LUTS has not to our knowledge been previously examined.

METHODS

Prostate tissue specimens from 53 patients (ages 47-88, mean 65.1) treated by open simple prostatectomy or transurethral resection of the prostate for BPH/LUTS were stained to quantitatively assess prostate inflammation and collagen content. Patients with prostate cancer present in greater than 5% of the surgical specimen were excluded. Prostate volume was determined from pelvic CT scan obtained within 2 years of surgery.

RESULTS

Analysis of the data showed that inflammation was inversely correlated with collagen content (r = -0.28, p = 0.04). In men with prostates less than 75 cm3 inflammation increases and collagen content decreases with prostate volume (p = 0.002 and p = 0.03, respectively) while in men with prostate volume over 75 cm3 inflammation decreases and collagen content increases with prostate volume (p = 0.30 and p = 0.005, respectively).

CONCLUSIONS

Our data do not support the assumed positive association of prostate inflammation with collagen content. Coordinated analysis of scatter plots of inflammation and collagen content with prostate volume revealed a subset of prostates with volumes >50 cm3 prostate characterized by intense inflammation and low collagen content and it is this subgroup that appears most responsible for the inverse correlation of inflammation and collagen.

Polychlorinated Biphenyls (PCBs) Impact Prostatic Collagen Density and Bladder Volume in Young Adult Mice Exposed during in Utero and Lactational Development

Polychlorinated biphenyls (PCBs) are persistent organic pollutants linked to deleterious health outcomes, including voiding dysfunction in developmentally exposed mice. Changes in prostate volume and/or extracellular matrix composition are associated with voiding dysfunction in men and animal models. Whether PCB-induced changes in voiding function in male mice occur in part via alterations to the prostate or an alternate mechanism is unclear. Therefore, we tested whether developmental exposure to the MARBLES PCB mixture altered prostate morphology in young adult offspring. C57Bl/6J female mice were dosed daily with the MARBLES PCB mixture at 0, 0.1, 1 or 6 mg/kg/d for two weeks prior to mating and through gestation and lactation, offspring were collected at 6 weeks of age. Ventral prostate mass was decreased in the 1 mg/kg/d PCB group compared to other PCB groups. There were no PCB-induced changes in prostate smooth muscle thickness, apoptosis, proliferation, or testes mass. PCBs impacted the prostate extracellular matrix; anterior prostate collagen density was decreased in the 1 mg/kg/d PCB group compared to all other groups. Normalized bladder volume was increased in male and female offspring in the 6 mg/kg/d PCB group compared to control. No change in water consumption, bladder mass or bladder smooth muscle thickness accompanied changes in bladder volume. Urine and serum creatinine concentrations were elevated but only in male mice. Together, these results suggest that developmental exposure to PCBs can influence prostate wet weight and prostate/bladder morphology, but PCBs do not promote prostate enlargement. Whether these changes persist throughout adult life and how they contribute to voiding function in animal models and humans is of future interest.

Real-Time Void Spot Assay

Normal voiding behavior is the result of the coordinated function of the bladder, the urethra, and the urethral sphincters under the proper control of the nervous system. To study voluntary voiding behavior in mouse models, researchers have developed the void spot assay (VSA), a method that measures the number and area of urine spots deposited on a filter paper lining the floor of an animal's cage. Although technically simple and inexpensive, this assay has limitations when used as an end-point assay, including a lack of temporal resolution of voiding events and difficulties quantifying overlapping urine spots. To overcome these limitations, we developed a video-monitored VSA, which we call real-time VSA (RT-VSA), and which allows us to determine voiding frequency, assess voided volume and voiding patterns, and make measurements over 6 h time windows during both the dark and light phases of the day. The method described in this report can be applied to a wide variety of mouse-based studies that explore the physiological and neurobehavioral aspects of voluntary micturition in health and disease states.

The impact of short term, long term and intermittent E. coli infection on male C57BL/6J mouse prostate histology and urinary physiology

Prostatic inflammation and prostatic fibrosis are associated with lower urinary tract dysfunction in men. Prostatic inflammation arising from a transurethral uropathogenic E. coli infection is sufficient to increase prostatic collagen content in male mice. It is not known whether and how the sequence, duration and chronology of prostatic infection influence urinary function, prostatic inflammation and collagen content. We placed a transurethral catheter into adult male C57BL/6J mice to deliver uropathogenic E. coli UTI189 two-weeks prior to study endpoint (to evaluate the short-term impact of infection), 10-weeks prior to study endpoint (to evaluate the long-term impact of infection), or two-, six-, and ten-weeks prior to endpoint (to evaluate the impact of repeated intermittent infection). Mice were catheterized the same number of times across all experimental groups and instilled with sterile saline when not instilled with E. coli to control for the variable of catheterization. We measured bacterial load in free catch urine, body weight and weight of bladder and dorsal prostate; prostatic density of leukocytes, collagen and procollagen 1A1 producing cells, and urinary function. Transurethral E. coli instillation caused more severe and persistent bacteriuria in mice with a history of one or more transurethral instillations of sterile saline or E. coli. Repeated intermittent infections resulted in a greater relative bladder wet weight than single infections. However, voiding function, as measured by the void spot assay, and the density of collagen and ProCOL1A1+ cells in dorsal prostate tissue sections did not significantly differ among infection groups. The density of CD45+ leukocytes was greater in the dorsal prostate of mice infected two weeks prior to study endpoint but not in other infection groups compared to uninfected controls.

Male Lower Urinary Tract Dysfunction: An Underrepresented Endpoint in Toxicology Research

Lower urinary tract dysfunction (LUTD) is nearly ubiquitous in men of advancing age and exerts substantial physical, mental, social, and financial costs to society. While a large body of research is focused on the molecular, genetic, and epigenetic underpinnings of the disease, little research has been dedicated to the influence of environmental chemicals on disease initiation, progression, or severity. Despite a few recent studies indicating a potential developmental origin of male LUTD linked to chemical exposures in the womb, it remains a grossly understudied endpoint in toxicology research. Therefore, we direct this review to toxicologists who are considering male LUTD as a new aspect of chemical toxicity studies. We focus on the LUTD disease process in men, as well as in the male mouse as a leading research model. To introduce the disease process, we describe the physiology of the male lower urinary tract and the cellular composition of lower urinary tract tissues. We discuss known and suspected mechanisms of male LUTD and examples of environmental chemicals acting through these mechanisms to contribute to LUTD. We also describe mouse models of LUTD and endpoints to diagnose, characterize, and quantify LUTD in men and mice.

mMCP7, a Mouse Ortholog of δ Tryptase, Mediates Pelvic Tactile Allodynia in a Model of Chronic Pelvic Pain

Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS) is a condition that affects a large number of men and has unknown etiology. We have previously demonstrated the presence of elevated levels of mast cell tryptase in expressed prostatic secretions (EPS) of CP/CPPS patients. In a murine model of CP/CPPS, we showed tryptase and its cognate receptor PAR2 as critical to the development of pelvic pain and lower urinary tract symptoms. Here, we extend these observations to demonstrate that an isoform of tryptase called delta (δ)-tryptase, is elevated in the EPS of patients with CP/CPPS and is correlated with pelvic pain symptoms. Using an Escherichia coli (CP1) -induced murine model of CP/CPPS, we demonstrated a differential response in C57BL/6J and NOD/ShiLtJ mice, with C57BL6/J mice being resistant to an increase in pelvic tactile allodynia, despite having equivalent levels of activated mast cells in the prostate. Activated tryptase+ve mast cells were observed to be in closer apposition to PGP9.5+ve nerve fibers in the prostate stroma of NOD/ShiLtJ in comparison to C57BL/6J mice. The mouse ortholog of δ-tryptase, mouse mast cell protease 7 (mMCP7) has been reported to be unexpressed in C57BL/6J mice. We confirmed the absence of mMCP7 in the prostates of C57BL/6J and its presence in NOD/ShiLtJ mice. To evaluate a role for mMCP7 in the differential allodynia responses, we performed direct intra-urethral instillations of mMCP7 and the beta (β)-tryptase isoform ortholog, mMCP6 in the CP1-infection model. mMCP7, but not mMCP6 was able to induce an acute pelvic allodynia response in C57BL/6J mice. In-vitro studies with mMCP7 on cultured mast cells as well as dissociated primary neurons demonstrated the ability to induce differential activation of pain and inflammation associated molecules compared to mMCP6. We conclude that mMCP7, and possibility its human ortholog δ-tryptase, may play an important role in mediating the development of pelvic tactile allodynia in the mouse model of pelvic pain and in patients with CP/CPPS.

Association between the presence of bacteria in prostate tissue and histopathology in biopsies from men not complaining of lower urinary tract symptoms

OBJECTIVE

To investigate the presence of bacteria in prostate tissue, and relationships between the bacteria and histopathological findings.

METHODS

Samples were collected from prostate biopsy patients with no obvious lower urinary tract symptoms (LUTS). Detection and identification of bacterial species in the prostate tissues were performed with PCR for 16SrDNA and DNA sequencing. Histopathology was also evaluated. LUTS and lower urinary tract function were assessed by questionnaires, uroflowmetry, and ultrasonography.

RESULTS

DNA was extracted from 97 prostate biopsies, with 5 bacterial species detected among samples from 7 patients (7.2%). The stroma-to-gland ratio in the prostate tissues from patients with bacteria was lower than in those without bacteria (p < 0.01). Glandular epithelial hyperplasia was also identified in the prostates harboring bacteria. International Prostate Symptom Score (IPSS), IPSS-quality of life (IPSS-QOL), Overactive Bladder Symptom Score (OABSS), maximum flow rate, urine volume by uroflowmetry, and post-voided residual urine were not significantly different when comparing patients with and without bacteria in their prostate samples.

CONCLUSIONS

The present study demonstrated that 7.2% of men without obvious LUTS had bacteria in their prostate tissues. The presence of such bacteria might induce glandular hyperplasia and contribute to pathological changes in the early stages of benign prostate enlargement before affecting LUTS.

A retrospective review of canine benign prostatic hyperplasia with and without prostatitis

Benign prostatic hyperplasia (BPH) is the most common prostatic disorder in older intact male dogs, but despite its prevalence, there are inconsistencies in clinical diagnosis and treatment. Although prostate size was historically considered the hallmark feature of BPH in men, currently, there is only a weak correlation between prostate size and clinical severity. We performed a retrospective cohort study with the primary objective of assessing clinical signs, ultrasonographic findings, treatments, and outcomes in dogs diagnosed with BPH, with and without concurrent prostatitis. We reviewed medical records and obtained data on presenting signs, prostatic imaging, and prevalence of concurrent bacteriuria. Prostate size was determined by ultrasonography and compared to the calculated expected size based on patient age and weight. Treatment and outcome were described for the cases with a minimum 2 months follow-up. Median age of dogs diagnosed with BPH was 8 years. Clinical signs were present in 16/25 dogs and scored as mild to moderate (median Zambelli's Symptom Index for BPH score 12). The median prostatic volume to body mass ratio was 1.60 mm³/kg. Prostate size did not correlate with the symptom severity. Concurrent bacteriuria was confirmed in 4/25 cases via bacterial culture and/or cytology. Treatments pursued and responses were only available in a subpopulation of dogs (n = 9) and were highly variable. Studies are needed to determine if current treatment options for BPH in dogs resolve associated clinical signs in addition to reducing prostate size.

Osteopontin Deficiency Ameliorates Prostatic Fibrosis and Inflammation

Fibrogenic and inflammatory processes in the prostate are linked to the development of lower urinary tract symptoms (LUTS) in men. Our previous studies identified that osteopontin (OPN), a pro-fibrotic cytokine, is abundant in the prostate of men with LUTS, and its secretion is stimulated by inflammatory cytokines potentially to drive fibrosis. This study investigates whether the lack of OPN ameliorates inflammation and fibrosis in the mouse prostate. We instilled uropathogenic E. coli (UTI89) or saline (control) transurethrally to C57BL/6J (WT) or Spp1^tm1Blh/J (OPN-KO) mice and collected the prostates one or 8 weeks later. We found that OPN mRNA and protein expression were significantly induced by E. coli-instillation in the dorsal prostate (DP) after one week in WT mice. Deficiency in OPN expression led to decreased inflammation and fibrosis and the prevention of urinary dysfunction after 8 weeks. RNAseq analysis identified that E. coli-instilled WT mice expressed increased levels of inflammatory and fibrotic marker RNAs compared to OPN-KO mice including Col3a1, Dpt, Lum and Mmp3 which were confirmed by RNAscope. Our results indicate that OPN is induced by inflammation and prolongs the inflammatory state; genetic blockade of OPN accelerates recovery after inflammation, including a resolution of prostate fibrosis.

Mast cell function in prostate inflammation, fibrosis, and smooth muscle cell dysfunction

Intraurethral inoculation of mice with uropathogenic Escherichia coli (CP1) results in prostate inflammation, fibrosis, and urinary dysfunction, recapitulating some but not all of the pathognomonic clinical features associated with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). In both patients with LUTS and CP1-infected mice, we observed increased numbers and activation of mast cells and elevated levels of prostate fibrosis. Therapeutic inhibition of mast cells using a combination of a mast cell stabilizer, cromolyn sodium, and the histamine 1 receptor antagonist cetirizine di-hydrochloride in the mouse model resulted in reduced mast cell activation in the prostate and significant alleviation of urinary dysfunction. Treated mice showed reduced prostate fibrosis, less infiltration of immune cells, and decreased inflammation. In addition, as opposed to symptomatic CP1-infected mice, treated mice showed reduced myosin light chain-2 phosphorylation, a marker of prostate smooth muscle contraction. These results show that mast cells play a critical role in the pathophysiology of urinary dysfunction and may be an important therapeutic target for men with BPH/LUTS.NEW & NOTEWORTHY LUTS-associated benign prostatic hyperplasia is derived from a combination of immune activation, extracellular matrix remodeling, hyperplasia, and smooth muscle cell contraction in prostates of men. Using a mouse model, we describe the importance of mast cells in regulating these multiple facets involved in the pathophysiology of LUTS. Mast cell inhibition alleviates both pathology and urinary dysfunction in this model, suggesting the potential for mast cell inhibition as a therapeutic that prevents and reverses pathology and associated symptomology.

A NEW approach for characterizing mouse urinary pathophysiologies

The void spot assay (VSA) is a cost-effective method for evaluating and quantifying mouse urinary voiding phenotypes. The VSA has been used to differentiate voiding behaviors between experimental groups, but not as a diagnostic assay. To build toward this goal, we used the VSA to define voiding patterns of male mice with diabetic diuresis (BTBR.Cg-Lepob /WiscJ mice), irritative urinary dysfunction (E. coli UTI89 urinary tract infection), and obstructive urinary dysfunction (testosterone and estradiol slow-release implants) compared to their respective controls. Many studies compare individual VSA endpoints (urine spot size, quantity, or distribution) between experimental groups. Here, we consider all endpoints collectively to establish VSA phenomes of mice with three different etiologies of voiding dysfunction. We created an approach called normalized endpoint work through (NEW) to normalize VSA outputs to control mice, and then applied principal components analysis and hierarchical clustering to 12 equally weighted, normalized, scaled, and zero-centered VSA outcomes collected from each mouse (the VSA phenome). This approach accurately classifies mice based on voiding dysfunction etiology. We used principal components analysis and hierarchical clustering to show that some aged mice (>24 m old) develop an obstructive or a diabetic diuresis VSA phenotype while others develop a unique phenotype that does not cluster with that of diabetic, infected, or obstructed mice. These findings support use of the VSA to identify specific urinary phenotypes in mice and the continued use of aged mice as they develop urinary dysfunction representative of the various etiologies of LUTS in men.

The influence of intermittent hypoxia, obesity, and diabetes on male genitourinary anatomy and voiding physiology

We used male BTBR mice carrying the Lep^ob mutation, which are subject to severe and progressive obesity and diabetes beginning at 6 wk of age, to examine the influence of one specific manifestation of sleep apnea, intermittent hypoxia (IH), on male urinary voiding physiology and genitourinary anatomy. A custom device was used to deliver continuous normoxia (control) or IH to wild-type and Lep^ob/ob (mutant) mice for 2 wk. IH was delivered during the 12-h inactive (light) period in the form of 90 s of 6% O₂ followed by 90 s of room air. Continuous room air was delivered during the 12-h active (dark) period. We then evaluated genitourinary anatomy and physiology. As expected for the type 2 diabetes phenotype, mutant mice consumed more food and water, weighed more, and voided more frequently and in larger urine volumes. They also had larger bladder volumes but smaller prostates, seminal vesicles, and urethras than wild-type mice. IH decreased food consumption and increased bladder relative weight independent of genotype and increased urine glucose concentration in mutant mice. When evaluated based on genotype (normoxia + IH), the incidence of pathogenic bacteriuria was greater in mutant mice than in wild-type mice, and among mice exposed to IH, bacteriuria incidence was greater in mutant mice than in wild-type mice. We conclude that IH exposure and type 2 diabetes can act independently and together to modify male mouse urinary function. NEW & NOTEWORTHY Metabolic syndrome and obstructive sleep apnea are common in aging men, and both have been linked to urinary voiding dysfunction. Here, we show that metabolic syndrome and intermittent hypoxia (a manifestation of sleep apnea) have individual and combined influences on voiding function and urogenital anatomy in male mice.

A uropathogenic E. coli UTI89 model of prostatic inflammation and collagen accumulation for use in studying aberrant collagen production in the prostate

Bacterial infection is one known etiology of prostatic inflammation. Prostatic inflammation is associated with prostatic collagen accumulation and both are linked to progressive lower urinary tract symptoms in men. We characterized a model of prostatic inflammation using transurethral instillations of Escherichia coli UTI89 in C57BL/6J male mice with the goal of determining the optimal instillation conditions, understanding the impact of instillation conditions on urinary physiology, and identifying ideal prostatic lobes and collagen 1a1 prostatic cell types for further analysis. The smallest instillation volume tested (50 µL) distributed exclusively to the bladder, 100- and 200-µL volumes distributed to the bladder and prostate, and a 500-µL volume distributed to the bladder, prostate, and ureter. A threshold optical density of 0.4 E. coli UTI89 in the instillation fluid was necessary for significant (P < 0.05) prostate colonization. E. coli UTI89 infection resulted in a low frequency, high volume spontaneous voiding pattern. This phenotype was due to exposure to E. coli UTI89, not catheterization alone, and was minimally altered by a 50-µL increase in instillation volume and doubling of E. coli concentration. Prostate inflammation was isolated to the dorsal prostate and was accompanied by increased collagen density. This was partnered with increased density of protein tyrosine phosphatase receptor type C+, procollagen type I-α1+ copositive cells and decreased density of α2-smooth muscle actin+, procollagen type I-α1+ copositive cells. Overall, we determined that this model is effective in altering urinary phenotype and producing prostatic inflammation and collagen accumulation in mice.