Nonbacterial prostatitis caused by partial urethral obstruction in the rat

Urethral monopolar cauterization: alternative infravesical obstruction model in male rats

OBJECTIVE:

We aimed to determine which method gives the most consistent results between urethral monopolar cauterization and standard urethral partial ligation methods for the urethral obstruction model.

METHODS:

Thirty male rats were randomly divided into control, partial ligation, and monopolar cauterization groups. Six weeks after experimental procedures, the experimental groups were evaluated cystometrically, biochemically, and histologically.

RESULTS:

According to the cystometric results, bladder capacity, baseline bladder pressure, and compliance data of the monopolar cauterization group were higher than those of the partial ligation and monopolar cauterization groups (p<0.05 and p<0.01, respectively). As a biochemical evaluation, malondialdehyde levels in bladder tissues of group control were higher than partial ligation and monopolar cauterization groups (p<0.05 and p<0.01, respectively). The collagen type I level of the control group was higher than the partial ligation and monopolar cauterization groups (p<0.01 and p<0.05, respectively). Collagen type III levels of the monopolar cauterization group were higher than those of the control group (p<0.01), but the Collagen type I/Collagen type III and transforming growth factor-β levels of the monopolar cauterization group were significantly lower than those of the control group (p<0.001). As a histological evaluation (hematoxylin and eosin), fibrosis in the lamina propria was more prominent in the monopolar cauterization group than in the control group (p<0.05). In addition, the muscular thickness was higher in the monopolar cauterization group compared with control and partial ligation groups (p<0.001 and p<0.01, respectively).

CONCLUSION:

The needle-tipped monopolar cauterization of the posterior urethra may be the method of choice for creating a chronic infravesical obstruction model of infravesical obstruction in male rats.

Pain in chronic prostatitis and the role of ion channels: a brief overview

BACKGROUND

Prostatitis is the third most common urologic condition affecting more than half the male population at some point in their lives. There are different categories of prostatitis, of which approximately 90% of cases can be classified under the National Institute of Health (NIH) type III category (chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)) with no causative agents identified. CP/CPPS is associated with several symptoms, of which the most prominent being chronic pain. Despite its high incidence, pain management in patients with CP/CPPS has been poor, possibly due to the lack of understanding of aetiological factors and mechanisms underlying pain development.

METHODS

An extensive literature search of published articles on the molecular mechanisms of pain in CP/CPPS was conducted using PubMed and Google Scholar search engines (https://pubmed.ncbi.nlm.nih.gov and https://scholar.google.com). The terms used for the search were: prostatitis, pain mechanism in CP/CPPS, prostatitis pain models, acid-sensing ion channels (ASICs), transient receptor potential vanilloid type 1 (TRPVs), purinergic channels (P2X) in prostatitis pain mechanism and inflammatory mediators in CP/CPPS. The papers were identified based on the title and abstract, and after excluding the articles that did not emphasize the pain mechanism in CP/CPPS. Ninety-five articles (36 review and 59 original research papers) met our criteria and were included in the review.

RESULTS

A number of inflammatory mediator molecules and pain channels, including ASICs, transient receptor potential vanilloid channels (TRPVs) and P2Xs have been investigated for their role in prostatitis pain pathology using various animal models.

CONCLUSION

This review summarizes the pain mechanisms in CP/CPPS focusing on the inflammatory mediators, neurotransmitters, pain-transducing ion channels and small animal models developed for studying prostatitis.

Lymphoplasmacytic prostatitis associated with urethral obstruction in a dog; a case report

A 10-year-old, male intact, mixed breed dog was admitted with a history of intermittent lower urinary tract signs of eighteen-months duration. Dysuria, stranguria, pollakiuria and overflow incontinence developed 2 weeks prior to presentation, while vomiting, polydipsia and anorexia were seen a few days prior to admission. Physical examination revealed prostatomegaly. Biochemistry results were compatible with postrenal azotemia. Abdominal imaging confirmed prostatomegaly with consequent urethral obstruction, and ultrasound-guided fine needle aspiration cytology of the prostate gland was consistent with granulomatous inflammation. The dog was hospitalized, urethral patency was preserved and upon laparotomy a cystostomy tube was placed, and prostatic biopsy was obtained. Orchiectomy was also performed. Urine culture performed two days prior to the surgery was negative. Prostatic histopathology revealed mild to moderate lymphoplasmacytic prostatitis. Three months postoperatively, clinical signs had resolved completely and urinations remained normal while the dog is still in good health three years after diagnosis. This is the first case of canine lymphoplasmacytic prostatitis in which clinical signs, diagnostic evaluation, management and long-term follow up are available.

Immunological Mechanisms Underlying Chronic Pelvic Pain and Prostate Inflammation in Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is the most common urologic morbidity in men younger than 50 years and is characterized by a diverse range of pain and inflammatory symptoms, both in type and severity, that involve the region of the pelvis, perineum, scrotum, rectum, testes, penis, and lower back. In most patients, pain is accompanied by inflammation in the absence of an invading infectious agent. Since CP/CPPS etiology is still not well established, available therapeutic options for patients are far from satisfactory for either physicians or patients. During the past two decades, chronic inflammation has been deeply explored as the cause of CP/CPPS. In this review article, we summarize the current knowledge regarding immunological mechanisms underlying chronic pelvic pain and prostate inflammation in CP/CPPS. Cumulative evidence obtained from both human disease and animal models indicate that several factors may trigger chronic inflammation in the form of autoimmunity against prostate, fostering chronic prostate recruitment of Th1 cells, and different other leukocytes, including mast cells, which might be the main actors in the consequent development of chronic pelvic pain. Thus, the local inflammatory milieu and the secretion of inflammatory mediators may induce neural sensitization leading to chronic pelvic pain development. Although scientific advances are encouraging, additional studies are urgently needed to establish the relationship between prostatitis development, mast cell recruitment to the prostate, and the precise mechanisms by which they would induce pelvic pain.

Therapeutic effect of melittin on a rat model of chronic prostatitis induced by Complete Freund's Adjuvant

OBJECTIVES

The present study was aimed to establish a model of chronic prostatitis in rat with the use of intraprostatic injection of Complete Freund's Adjuvant, and to examine the anti-inflammatory and analgesic effects of melittin on the newly-developed chronic prostatic pain model.

METHODS

Adult male Sprague-Dawley rats were injected with Complete Freund's Adjuvant (CFA) into the prostate. Twelve days after model rats of the treatment group were injected melittin into the prostate, while those of the control group received sterile saline injection. The nociceptive effects of CFA were evaluated by using a behavior approach (i.e. mechanical pain threshold measurement) on the day of CFA injection and 6, 12, and 18days after CFA injection. After the in-live study was done, the prostate was collected for histological examination of inflammatory cell infiltration. Levels of cyclooxygenase (COX)-2 in prostate and glial fibrillary acidic protein (GFAP) in spinal cord were determined using immunohistochemistry. Rats of the sham control group received intraprostatic injection of sterile saline and were studied using the same methods RESULTS: Intraprostatic CFA injection induced local allodynia that lasted over at least 2 weeks. The pain behavior of rat was associated with increases in inflammatory cell infiltration into the prostate. Levels of COX-2 in prostate and GFAP in spinal cord were also elevated. Treatment with melittin significantly raised pain threshold, decreased inflammatory infiltrates, and suppressed COX-2 and GFAP expression.

CONCLUSION

Intraprostatic injection of CFA induced neurogenic prostatitis and prostatic pain. The established model will be useful to the study of CP/CPPS pathogenesis. Melittin demonstrated profound anti-inflammatory and analgesic effects on the chronic prostatic pain model, suggesting melittin may hold promise as a novel therapeutic for treatment of CP/CPPS.

Intraprostatic Reflux of Urine Induces Inflammation in a Rat

BACKGROUND

We examined whether urine reflux into the prostate can induce prostatic inflammation in a rat and evaluated the effect of α1-adrenoreceptor antagonist.

METHODS

Experiment 1: Male Sprague-Dawley rats were injected with 500 µl of Evans Blue through the urethral orifice. Intravesical pressure was measured, and the prostate was excised to evaluate urine reflux. Experiment 2: Rats were injected with 500 µl urine or saline (control) from the urethral orifice. Silodosin (200 µg/kg/day) was administered to the silodosin group. We evaluated histopathology, the expression of proinflammatory cytokines and oxidative stress markers of the prostate on day 7, after assessing the prostatic microcirculation and cystometrogram.

RESULTS

Experiment 1: The histopathology showed that Evans Blue instilled through the urethral orifice entered the prostatic ducts. Intravesical pressure during Evans Blue instillation was 47.7 ± 1.6 cmH₂ O (mean ± standard error). Experiment 2: On day 7 after urine instillation through the urethral orifice, histopathology showed infiltrated inflammatory cells in the peri-glandular stroma. Inflammation-associated proteins (IL-1α, IL-1β, IL-6, and TNFα) were upregulated in the urine-instilled rats but not in the silodosin group. Erythrocyte speed on the prostatic surface, immunostaining for hypoxyprobe, and quantification of oxidative stress markers (MDA and HIF-1α) demonstrated prostatic hypoxia in the urine-instilled rats, which was ameliorated in the silodosin group. Cystometrogram revealed a shorter intercontraction interval in the urine-instilled rats, which was prolonged in the silodosin group.

CONCLUSIONS

Urine reflux into the prostatic duct induces abacterial prostatitis. Silodosin relieved prostatic inflammation and bladder overactivity by increasing microcirculation in the prostate. Prostate 77:164-172, 2017. © 2016 Wiley Periodicals, Inc.

Sneezing during Micturition: A Possible Trigger of Acute Bacterial Prostatitis

A perfectly well 39-year-old man sneezed during micturition and developed classic features of acute bacterial prostatitis corroborated by laboratory evidence of prostatic inflammation/infection. The prostate-specific antigen level at presentation was 9.6 ng/mL and declined to 1.23 ng/mL one month later on levofloxacin. This is the first report in the medical literature of sneezing while voiding being a possible trigger of acute bacterial prostatitis. A biologically plausible mechanism is provided.

Histopathological classification criteria of rat model of chronic prostatitis/chronic pelvic pain syndrome

OBJECTIVE

A variety of murine models of experimental prostatitis that mimic the phenotype of human chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) have been developed. However, there is still a lack of explicit diagnosis criteria about those animal model. Our study is to establish histopathological classification criteria, which will be conducive to evaluate the animal models.

METHODS

We firstly established a rat model of experimental autoimmune prostatitis that is considered a valid model for CP/CPPS. For modelling, male Sprague-Dawley rats were immunized with autologous prostate tissue homogenate supernatant emulsified with complete Freund's adjuvant by subcutaneous injection into abdominal flank and simultaneously immunized with pertussis-diphtheria-tetanus vaccine by intraperitoneal injection. Three immunizations were administered semimonthly. At the 45th day, animals were killed, and prostate tissues were examined for morphology.

RESULTS

Histologically, the prostate tissues were characterized by lymphoproliferation, atrophy of acini, and chronic inflammatory cells infiltration in the stromal connective tissue around the acini or ducts. Finally, we built histopathological classification criteria incorporating inflammation locations (mesenchyme, glands, periglandular tissues), ranges (focal, multifocal, diffuse), and grades (grade I-IV). To verify the effectiveness and practicability of the histopathological classification criteria, we conducted the treatment study with one of the alpha blockers, tamsulosin.

CONCLUSION

The histopathological classification criteria of rat model of CP/CPPS will serve for further research of the pathogenesis and treatment strategies of the disease.

Chronic inflammation in the pathogenesis of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a common disorder affecting 50-80% of the aged male population. Androgens and age have been traditionally considered the main determinants of prostate enlargement, but in the last years a potentially important role of chronic inflammation in BPH pathogenesis has emerged. Bacterial and non-infectious chronic prostatitis could represent inciting factors leading to tissue hyperproliferation, possibly via the recently demonstrated antigen-presenting capacity of prostatic stromal cells, enabling them to induce and sustain intraglandular immune responses. The prostate growth-promoting chemokine IL-8 could represent a direct link between chronic prostate inflammation and autocrine/paracrine stromal cell proliferation, in agreement with its marked secretion induced in BPH stromal cells by a combination of Th1 and Th17 cell-derived inflammatory cytokines. BPH stromal cells express the vitamin D receptor (VDR), which is up-regulated by exposure to inflammatory stimuli. The non-hypercalcaemic VDR agonist elocalcitol, shown to arrest BPH development by decreasing the intra-prostatic androgen signalling without directly interfering with systemic androgen action, exerts immunoregulatory and anti-inflammatory properties in different prostatic pathology characterized by growth and inflammation. The mechanism of action of VDR agonists supports an important role of chronic inflammation in BPH pathogenesis and strengthens the concept of these agents as a therapeutic option for pharmacological treatment of BPH.

Prevalence, incidence estimation, risk factors and characterization of chronic prostatitis/chronic pelvic pain syndrome in urological hospital outpatients in Italy: results of a multicenter case-control observational study

PURPOSE

We evaluated the prevalence and estimated the incidence and risk factors of chronic prostatitis/chronic pelvic pain syndrome in urological hospital outpatients in Italy.

MATERIALS AND METHODS

From January to June 2006 patients from 28 Italian urological centers who were between 25 and 50 years old with symptoms of chronic prostatitis/chronic pelvic pain syndrome were consecutively enrolled in this prospective epidemiological case-control study. A total of 152 subjects of similar age, race and area of origin who were investigated for infertile couples but were otherwise healthy served as controls. All subjects provided a medical history and underwent different symptom scorings, clinical evaluation and microbiological tests.

RESULTS

Of 5,540 male urological outpatients 764 with chronic prostatitis/chronic pelvic pain syndrome were enrolled, including 225 (29.4%) at the first presentation and 539 (70.6%) who underwent previous treatment. Thus, the prevalence of the syndrome was 13.8%, while the estimated incidence was 4.5%. Cigarette smoking, a high caloric diet with low fruit and vegetable consumption, constipation, meteorism, slow digestion, a sexual relationship with more than 1 partner and coitus interruptus were more likely in patients with chronic prostatitis/chronic pelvic pain syndrome than in controls (each p <0.001). The syndrome had a negative influence on sexual desire, erectile dysfunction and premature ejaculation (p <0.001). The Meares and Stamey test was positive in 13.3% of patients and in 2.9% of controls. Urethral swabs in patients with a negative Meares and Stamey test were positive for sexually transmitted pathogens in 6%.

CONCLUSIONS

The prevalence and estimated incidence of chronic prostatitis/chronic pelvic pain syndrome in urological hospital outpatients in Italy are high. The syndrome is closely related to lifestyle, diet, smoking, gastrointestinal or anorectal disease and impaired sexual function.

Urodynamic changes in a noble rat model for nonbacterial prostatic inflammation

BACKGROUND

Chronic nonbacterial prostatitis (CP) associated with voiding dysfunction is a poorly understood clinical phenomenon. The goal of the present study was to induce prostatic inflammation with estrogen and androgen treatment and to record associated urodynamic changes in Noble rats.

METHODS

Rats were treated with estradiol and testosterone implants to increase estradiol concentration in serum while testosterone concentration was maintained at or slightly above the control level. The urodynamical recordings were performed under anesthesia after the hormone treatments for 3 and 6 weeks. The dorsolateral lobes of the prostates were removed for histopathological analysis after recordings.

RESULTS

After the 3-week treatment, lymphocytes, mainly T-cells, were located around the capillaries. During the following 3 weeks lymphocytes migrated into stroma and acini. Cytotoxic T-cells were seen intraepithelially, and neutrophiles inside the acini. Removal of estrogen implant or treatment with anti-estrogen diminished inflammation. No changes in voiding pattern were seen after the 3-week treatment. Three weeks later, bladder weight and capacity were increased, and the micturition time was prolonged.

CONCLUSIONS

Elevated estrogen concentration was essential for the gradual development of prostatic inflammation. The profile and location of inflammatory cells suggest that prostatic vasculature is one of the sites of estrogen action. Urodynamic changes which developed in association with glandular inflammation indicated abnormal bladder function, reflecting an incipient obstruction.

Experimental rodent models of prostatitis: limitations and potential

Prostatitis is a polyetiological inflammation of the prostate gland in men characterized by pelvic pain, irritative voiding symptoms, and sexual dysfunction. Histologically prostatitis is characterized by poly- and mononuclear cell infiltrates (neutrophils, lymphocytes, macrophages and plasma cells) in the stromal connective tissue around the acini or ducts. Prostatitis is an important worldwide health problem in men. The pathogenesis and diagnostic criteria for the condition are obscure, with the result that the development of management programs for this condition has been hindered. Animal model(s) might be useful in elucidating mechanisms involved in the molecular pathogenesis of chronic nonbacterial prostatitis and chronic pelvic pain syndrome. Given that prostatitis might have a multifactorial etiology, several animal models with unique features may prove helpful. This review examines a number of experimental rodent models of prostatitis and evaluates their advantages and limitations.

Evaluation of two techniques of partial urethral obstruction in the male rat model of bladder outlet obstruction

OBJECTIVES

To perform a comparison to determine which of two methods of partial urethral ligation produces the most consistent outcome and fewest side effects. Such a study has not been previously reported. Partial urethral ligation is a means of causing reproducible bladder outlet obstruction. In the male rat model, partial urethral obstruction can be performed either by perineal incision and bulbous urethral ligation or retropubic incision and midprostatic obstruction.

METHODS

Fifteen male Sprague-Dawley rats were studied. Five were selected for bulbous urethral obstruction through a perineal incision, five for midprostatic obstruction using a retropubic approach, and five for a sham operation through a perineal incision.

RESULTS

The operative time was shorter and morbidity lower with the perineal approach compared with the retropubic approach. Inflammation or infection, or both, were seen in the prostate, bladder, proximal urethra, ureters, and kidneys in the rats in which a midprostatic obstruction was performed. The proximal urethra and prostate were mildly inflamed in those rats that underwent bulbous obstruction. Sham-operated rats exhibited mild prostatitis only.

CONCLUSIONS

The perineal approach to the bulbous urethra is the method of choice for creating a partial urethral obstruction model of bladder outlet obstruction in the male rat.

Therapeutic effect of transurethral needle ablation in non-bacterial prostatitis: chronic pelvic pain syndrome type IIIa

AIM

Non-bacterial prostatitis is difficult to manage with conventional treatment. This study was undertaken to evaluate the therapeutic effect of transurethral needle ablation (TUNA) on men with chronic inflammatory non-bacterial prostatitis.

METHODS

Thirty-two patients with non-bacterial prostatitis (type IIIa) were treated with TUNA. The TUNA procedure, which uses radiofrequency energy, heats the prostate tissue to approximately 90-110 degrees C over a 5-min period. Evaluation consisted of a prostatitis symptom severity score chart, the monitoring of the leukocyte count in the expressed prostatic secretion (EPS) and a subjective global assessment.

RESULTS

The decrease in the prostate symptom severity score chart at 3 and 6 months compared with the baseline assessment was statistically significant. Analysis of the leukocyte levels in the EPS in 14 patients was available. All 14 patients had a decrease in the EPS leukocyte count 3 months after treatment. However, six of these men (43%) still had EPS leukocyte levels above the normal indices (>10 white blood cells per high-power field). A second session of TUNA on these partial responders resulted in three of the six men obtaining a normal EPS leukocyte count. At 6 months following treatment, complete, partial and poor improvement in terms of subjective global assessment were noted in 60, 35 and 5% of patients, respectively. No major complications, including those of sexual dysfunction or retrograde ejaculation, were noted in this cohort.

CONCLUSIONS

Transurethral needle ablation appears to be an easy, safe and effective treatment for men with chronic inflammatory non-bacterial prostatitis.