CELL RELATIONSHIP IN A WISTAR RAT MODEL OF SPONTANEOUS PROSTATITIS

Autonomic Nervous System Dysfunction Is Related to Chronic Prostatitis/Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common and non-lethal urological condition with painful symptoms. The complexity of CP/CPPS's pathogenesis and lack of efficient etiological diagnosis results in incomplete treatment and recurrent episodes, causing long-term mental and psychological suffering in patients. Recent findings indicate that the autonomic nervous system involves in CP/CPPS, including sensory, sympathetic, parasympathetic, and central nervous systems. Neuro-inflammation and sensitization of sensory nerves lead to persistent inflammation and pain. Sympathetic and parasympathetic alterations affect the cardiovascular and reproductive systems and the development of prostatitis. Central sensitization lowers pain thresholds and increases pelvic pain perception in chronic prostatitis. Therefore, this review summarized the detailed processes and mechanisms of the critical role of the autonomic nervous system in developing CP/CPPS. Furthermore, it describes the neurologically relevant substances and channels or receptors involved in this process, which provides new perspectives for new therapeutic approaches to CP/CPPS.

Preclinical models and evaluation criteria of prostatitis

Prostatitis is a common urological condition that affects almost half of all men at some point in their life. The prostate gland has a dense nerve supply that contributes to the production of fluid to nourish sperm and the mechanism to switch between urination and ejaculation. Prostatitis can cause frequent urination, pelvic pain, and even infertility. Long-term prostatitis increases the risk of prostate cancer and benign prostate hyperplasia. Chronic non-bacterial prostatitis presents a complex pathogenesis, which has challenged medical research. Experimental studies of prostatitis require appropriate preclinical models. This review aimed to summarize and compare preclinical models of prostatitis based on their methods, success rate, evaluation, and range of application. The objective of this study is to provide a comprehensive understanding of prostatitis and advance basic research.

Applications of Vertebrate Models in Studying Prostatitis and Inflammation-Associated Prostatic Diseases

It has long been postulated that the inflammatory environment favors cell proliferation, and is conducive to diseases such as cancer. In the prostate gland, clinical data implicate important roles of prostatitis in the progression of both benign prostatic hyperplasia (BPH) and prostate cancer (PCa). However, their causal relationships have not been firmly established yet due to unresolved molecular and cellular mechanisms. By accurately mimicking human disease, vertebrate animals provide essential in vivo models to address this question. Here, we review the vertebrate prostatitis models that have been developed and discuss how they may reveal possible mechanisms by which prostate inflammation promotes BPH and PCa. Recent studies, particularly those involving genetically engineered mouse models (GEMMs), suggest that such mechanisms are multifaceted, which include epithelium barrier disruption, DNA damage and cell proliferation induced by paracrine signals, and expansion of potential cells of origin for cancer. Future research using rodent prostatitis models should aim to distinguish the etiologies of BPH and PCa, and facilitate the development of novel clinical approaches for prostatic disease prevention.

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.

Diagnostic and Management Strategies for Patients with Chronic Prostatitis and Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common and often heterogenous condition that can have severe consequences on patient quality of life. In this review, we describe the pathophysiology, diagnostic work-up, and treatment of patients with CP/CPPS incorporating the most recent literature. Studies have demonstrated that CP/CPPS involves a complex pathophysiology, including infectious, immunologic, neurologic, endocrinologic, and psychologic etiologies, with frequent intersections between the different entities. Despite robust research assessing a variety of therapeutics targeting these etiologies, clinical trials have failed to identify an empiric treatment strategy applicable specifically to older adult male patients with CP/CPPS. As such, it can be challenging to manage older male patients with this condition. The advent of clinical phenotyping of patients with CP/CPPS has led to advances in tailored management strategies. Monomodal therapy has been largely unsuccessful because of the unclear and complex etiology of CPPS. As a result, CP/CPPS therapy has transitioned to a multimodal approach, including both pharmacologic and non-pharmacologic therapies. The best studied pharmacologic therapies include antibiotics, alpha-blockers, anti-inflammatory and immunomodulatory agents, phytotherapies, phosphodiesterase inhibitors, hormonal agents, neuromodulatory agents, and antidepressants. The best studied non-pharmacological therapies include pelvic floor physical therapy, myofascial trigger point release, acupuncture and electroacupuncture, psychological support and biofeedback, and electrocorporeal shockwave therapy and local thermotherapy.

Influence of Experimental Autoimmune Prostatitis on Sexual Function and the Anti-inflammatory Efficacy of Celecoxib in a Rat Model

Experimental autoimmune prostatitis (EAP) is a well-established model induced by an autoimmune response to prostate antigen. The symptomatic, pathological, and immunological characteristics of EAP animals are highly consistent with human chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), which makes EAP an ideal model for this disease. Here, we investigate the influence of EAP on male rat sexual function and the efficacy of anti-inflammatory therapy with celecoxib. EAP rat models were established using male Wistar rats. Rats were randomly assigned to a normal control group, an EAP model group, or an EAP model with celecoxib treatment group (celecoxib group). Behavioral changes, sexual behavioral changes, and erectile function were estimated using an open-field test, a sucrose consumption test, mating experiments, and by intracavernous pressure/mean arterial pressure ratio (ICP/MAP). Histological changes in the prostate were observed by HE staining, and the serum inflammatory factors IL-1β and TNF-α levels were measured by enzyme-linked immunosorbent assay. In addition, serotonin (5-hydroxytryptamine, 5-HT), 5-HT_1A receptor, 5-HT_2C receptor, and serotonin transporter (SERT) expression levels in the hippocampus and spinal cord (T13–L1, L5–S2) were examined by immunohistochemistry and western blot analysis. Results showed that EAP rats exhibited characteristics of depression, decreased sexual drive, premature ejaculation, and increased threshold of penile erection. Moreover, all these changes were effectively alleviated by celecoxib. Significant increases in prostatic interstitial infiltration by inflammatory cells and in serum IL-1β and TNF-α levels were observed in EAP rats, and these were partially reduced by celecoxib. Additionally, the expression pattern of serotonin system regulators in the hippocampus and spinal cord were altered in EAP model rats, including a decrease in 5-HT levels and an increase in 5-HT_1A receptor levels. In conclusion, autoimmune prostatitis impaired rat sexual function, and this was effectively prevented by anti-inflammatory therapy with celecoxib. Moreover, a serotonin system disorder in the central nervous system was likely mediated via inflammation in EAP rats.

Experimental rat prostatitis caused by Trichomonas vaginalis infection

BACKGROUND

Trichomonas vaginalis (T. vaginalis) is the most common sexually transmitted parasite. It has been detected in prostatic tissue of patients with prostatitis and reported to be associated with chronic prostatitis and benign prostatic hyperplasia as well as prostate cancer. Recently, experimental rodent models of prostatitis induced by pathogen infection have been developed. However, there have so far been no reports of prostatitis caused by T. vaginalis infection in animals. Here, we investigated whether infection with T. vaginalis via the rat urethra could cause prostatitis.

METHODS

T. vaginalis was injected into prostate through urethra of rat (Wistar rats), and the rats were killed 1, 2, or 4 weeks later. The presence of T. vaginalis trophozoites in the rat prostates was examined by immunohistochemistry, and pathological changes of the prostate were observed by hematoxylin-eosin staining and evaluated by grading from 0 to 5 for inflammatory cell infiltration, acinar changes, and interstitial fibrosis. Infiltrated mast cells were observed by toluidine blue staining of rat prostate tissue. Chemokine C-C motif ligand 2 (CCL2) levels of the rat prostates were measured by ELISA.

RESULTS

T. vaginalis trophozoites were observed in acini in the prostates of the injected rats. The prostate tissues had higher pathological scores, and 83% (5/6) and 100% (6/6) of the ventral and dorsolateral lobes (n = 6), respectively, were inflamed. Infiltration and degranulation of mast cells were observed at higher rates in prostate sections of the T. vaginalis-infected rats. Also, prostate tissues of the injected rats had increased CCL2 levels.

CONCLUSIONS

Injection of T. vaginalis in rats caused prostatitis as revealed by pathologic changes, mast cell infiltration and increased CCL2 production. Therefore, this study provides the first evidence that T. vaginalis infection in rats causes prostatitis.

Rapamycin‑induced autophagy attenuates hormone‑imbalance‑induced chronic non‑bacterial prostatitis in rats via the inhibition of NLRP3 inflammasome‑mediated inflammation

Chronic non-bacterial prostatitis (CNBP) is a common urinary disease and no standard treatments are available at present. Although autophagy serves an important role in a variety of chronic diseases, its role in CNBP is yet to be fully elucidated. Therefore, the present study aimed to investigate the effects of rapamycin-induced autophagy on CNBP by establishing a rat model. In the present study, a total of 30 male Sprague-Dawley rats were randomly divided into three groups (n=10 per group): i) Control, in which rats underwent a sham operation; ii) the model (CNBP), in which rats were castrated and administered 17β-estradiol (0.25 mg/kg via subcutaneous injection) for 30 consecutive days; and iii) rapamycin treatment, in which rats were employed in accordance with the CNBP model, but also received a daily intraperitoneal injection of rapamycin (1 mg/kg) from the 16th day post-surgery for 15 days. Alterations in histology and the levels of autophagy-associated markers, and components of the NLRP3 inflammasome, were measured in the prostate tissues of the rats. The levels of molecules located further downstream of the NLRP3 inflammasome pathway, including interleukin (IL)-1β and IL-18, were also measured. The results demonstrated that, compared with the control group, increased infiltration levels of inflammatory cells and glandular epithelial degeneration were observed in the prostate tissues of rats with CNBP. Furthermore, a significant increase in the concentration of IL-1β and IL-18 in the serum, as well as the increased expression levels of NLRP3, ASC and caspase-1 in prostate tissues were also observed. In addition, reductions in the number of autophagosomes and the expression levels of autophagy-associated, including microtubule-associated protein 1 light chain 3β (LC3B) and Beclin 1, were also detected in the CNBP group; however, treatment with rapamycin reversed these effects. Collectively, the findings of the present study indicated that the NLRP3 inflammasome-mediated inflammatory response was activated by a hormonal imbalance in the prostate glands of rats; however, these effects may be suppressed via rapamycin-induced autophagy.

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.

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.

Role of mast cells in male chronic pelvic pain

PURPOSE

Chronic pelvic pain syndrome accounts for 90% of all chronic prostatitis but it has an unknown pathogenesis. We sought to understand the role of mast cells and nerve growth factor in chronic pelvic pain.

MATERIALS AND METHODS

Expressed prostatic secretions in men with chronic pelvic pain syndrome and controls were tested for mast cell tryptase and nerve growth factor. Mast cell number, activation status and nerve growth factor expression were examined in the NOD/ShiLtJ experimental autoimmune prostatitis model and in mast cell deficient KitW-sh/KitW-sh mice. Tactile allodynia was quantified using von Frey filaments as a measure of pelvic pain behavior. Inhibitors of mast cell degranulation, histamine receptor antagonists and anti-nerve growth factor neutralizing antibodies were tested to decrease pelvic pain behavior.

RESULTS

Men with chronic pelvic pain syndrome showed increased mast cell tryptase and nerve growth factor in expressed prostatic secretions. In the experimental autoimmune prostatitis model increased total and activated mast cells were observed in the prostate. Mast cell deficient KitW-sh/KitW-sh mice showed attenuated pelvic pain behavior but no difference in inflammatory infiltrates in the prostate from controls. Mice with experimental autoimmune prostatitis also demonstrated increased intraprostatic nerve growth factor compared to that of KitW-sh/KitW-sh mice. Treatment of experimental autoimmune prostatitis with a mast cell stabilizer combined with a histamine 1 receptor antagonist resulted in a synergistic decrease in chronic pelvic pain. In contrast, neutralization of nerve growth factor in vivo did not result in pain relief.

CONCLUSIONS

Results suggest that mast cells are important mediators of chronic pelvic pain in experimental autoimmune prostatitis cases. They may be potential targets for therapeutic intervention in men with chronic prostatitis/chronic pelvic pain syndrome.

Mast cells and ethanol consumption: interactions in the prostate, epididymis and testis of UChB rats

PROBLEM

Alcoholism has reached alarming proportions while fertility rates slowing in populations. The assessment of inflammatory effects with emphasis on the variation of the mast cells comparing ethanol chronic ingestion on reproductive organs deserves attention.

METHOD OF STUDY

The mast cells were investigated with light microscopy using toluidine blue to locate and count total mast cells and immunohistochemistry to identify the connective tissue mast cells (CTMC).

RESULTS

The increase in total mast cells in the prostate, total and degranulated mast cells in epididymis of UChB rats was accompanied by a greater proportion of mucosal mast cells (MMC) in these organs. In addition, a lower incidence of degranulated mast cells was observed in epididymis of control rats.

CONCLUSIONS

Ethanol increases the number of total and degranulated mast cells in the prostate and epididymis, as well as associated with increasing MMC, and therefore, it could be leading to inflammation in these organs.

CD4+ lymphocytes modulate prostate cancer progression in mice

Chronic inflammation contributes to the development of prostate cancer in humans. Here, we show that male Apc(Min/+) mice also develop prostate carcinoma with increasing age, mimicking that seen in humans in their 5th or 6th decade of life. Proinflammatory cytokines were significantly linked with cancer and increasing age in our mouse model; however, prostate and bowel tissues lacked evidence of inflammatory cell infiltrates other than mast cells. Lymphocytes protected against cancer, and protection from prostate cancer resided in antiinflammatory CD4(+)CD25(+) regulatory (T(REG)) cells that downregulated inflammatory cytokines. Supplementation with syngeneic T(REG) cells collected from wild-type mice reduced the levels of interleukin (IL)-6 (p < 0.05) and IL-9 (p < 0.001) and lowered prostate cancer risk (p < 0.05). Depletion of CD25(+) cells in 2-month-old animals increased the expression of IL-6 (p < 0.005) within prostate and increased the frequency of high-grade prostatic intraepithelial neoplasia (p < 0.05) and microinvasive prostatic carcinoma (p < 0.05) in dorsolateral prostate. Depletion of CD25(+) cells in young animals also increased the frequency of intestinal cancer in Min mice. Taken together, chronically elevated proinflammatory cytokines promoted carcinoma in Apc(Min/+) mice. T(REG) lymphocytes downregulated inflammation-associated carcinogenic processes and contributed to immune and epithelial homeostasis.

Mechanisms in prostatitis/chronic pelvic pain syndrome

PURPOSE

We reviewed the current literature on mechanisms involved in the pathogenesis of prostatitis/chronic pelvic pain syndrome (CPPS).

MATERIALS AND METHODS

A literature review for the years 1966 to 2003 was performed using the MEDLINE database of the United States National Library of Medicine.

RESULTS

National Institutes of Health categories I and II prostatitis result from identifiable prostatic infections, whereas patients with category IV are asymptomatic. The majority of symptomatic cases are category III or chronic prostatitis (CP)/CPPS. The etiology of CP/CPPS is unknown. The traditional marker of inflammation, namely white blood cells in prostatic fluids, does not correlate with the predominant symptom of pelvic pain. An imbalance toward increased proinflammatory and decreased anti-inflammatory cytokines has been implicated and a few studies have shown some correlation of this with pelvic pain. The imbalance in some men may result from polymorphisms at the cytokine loci. An autoimmune process may be involved and experimental evidence indicates that this can be under hormonal influence. Recent findings include possible defects in the androgen receptor. The prostate may not even be the source of the symptoms. Pelvic pain also correlates with the neurotrophin nerve growth factor implicated in neurogenic inflammation and central sensitization. Finally, psychological stress may produce measurable biochemical changes and influence the other processes. The role of normal prostatic bacterial flora in inciting the inflammatory response has also been reconsidered.

CONCLUSIONS

The symptoms of CP/CPPS appear to result from an interplay between psychological factors and dysfunction in the immune, neurological and endocrine systems.

A molecular analysis of prokaryotic and viral DNA sequences in prostate tissue from patients with prostate cancer indicates the presence of multiple and diverse microorganisms

BACKGROUND

Inflammation, both acute and chronic, is a common feature of prostate histology. While inflammation has been proposed to play an important role in both benign and malignant growth of the prostate, the stimuli for this inflammation remain poorly characterized. Infectious pathogens are potential stimuli for prostatic inflammation.

METHODS

Universal eubacterial PCR was used to test 170 prostate tissue core samples from 30 cancer patients for 16S rDNA gene sequences. Positive PCR products (n=64, 37%) were cloned and sequenced. For comparison, tissue samples from 30 patients were cultured using standard clinical microbiological techniques. DNA samples from 200 additional patients were tested by organism-specific PCR for the presence of Chlamydia trachomatis, Propionibacterium acnes, Trichomonas vaginalis, BK virus, Epstein-Barr virus, human cytomegalovirus, human papillomavirus, and xenotropic murine leukemia-related virus.

RESULTS

16S sequencing results indicated the presence of 83 distinct microorganisms. Microbiological culture isolated markedly fewer species. In general, organism-specific PCR failed to detect multiple organisms previously reported as common in the prostate. There was no significant association between the presence of particular species of bacteria and histologic evidence of acute or chronic inflammation.

CONCLUSIONS

Most prostates from men undergoing prostatectomy (87%) contain bacterial DNA from one or more species. However, the majority of individual tissue core samples were negative, suggesting regional heterogeneity in the presence of bacteria and a lack of a generalized or ubiquitous prostatic flora. Culture results suggest either the "unculturable" nature of species present in the prostate or that 16S rDNA sequences were derived from non-viable bacteria.

Autoimmune prostatitis: state of the art

The prostate is one of the main male sex accessory glands and the target of many pathological conditions affecting men of all ages. Pathological conditions of the prostate gland range from infections, chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) of a still unknown aetiology to benign hyperplasia and cancer. CP/CPPS is one of the most prevalent diseases in the urologic clinic and affects men younger than 50 years old. A significant advance in the understanding of CP/CPPS was made when an autoimmune response against prostate antigens was revealed in a considerable number of patients. During the last 30 years, extensive work has been done regarding the development and characterization of different rodent models of experimental autoimmune prostatitis (EAP). It has been demonstrated that tolerance to prostate antigens can be disrupted in some strains of rats and mice and cellular and humoral responses to prostate antigens are elicited. A Th1 pattern has been described and the cellular response seems to be the major pathogenic mechanism involved. Immune cells infiltrate the gland and induce prostate lesions. The genetic background and hormonal imbalance are factors that could contribute to the onset of the disease in susceptible young males. Moreover, spontaneous autoimmune prostatitis could also occur with advanced age in susceptible strains. In this review, we summarize the current knowledge regarding rodent models of EAP and the immunological alterations present in CP/CPPS patients. We also discuss the reliability of these experimental approaches as genuine tools for the study of human disease.

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.

Lycopene reduced gene expression of steroid targets and inflammatory markers in normal rat prostate

Epidemiological evidence links consumption of lycopene, the red carotenoid of tomato, to reduced prostate cancer risk. We investigated the effect of lycopene in normal prostate tissue to gain insight into the mechanisms, by which lycopene can contribute to primary prostate cancer prevention. We supplemented young rats with 200 ppm lycopene for up to 8 wk, measured the uptake into individual prostate lobes, and analyzed lycopene-induced gene regulations in dorsal and lateral lobes after 8 wk of supplementation. Lycopene accumulated in all four prostate lobes over time, with all-trans lycopene being the predominant isoform. The lateral lobe showed a significantly higher total lycopene content than the other prostate lobes. Transcriptomics analysis revealed that lycopene treatment mildly but significantly reduced gene expression of androgen-metabolizing enzymes and androgen targets. Moreover, local expression of IGF-I was decreased in the lateral lobe. Lycopene also consistently reduced transcript levels of proinflammatory cytokines, immunoglobulins, and immunoglobulin receptors in the lateral lobe. This indicates that lycopene reduced inflammatory signals in the lateral prostate lobe. In summary, we show for the first time that lycopene reduced local prostatic androgen signaling, IGF-I expression, and basal inflammatory signals in normal prostate tissue. All of these mechanisms can contribute to the epidemiologically observed prostate cancer risk reduction by lycopene.

Prostate carcinogenesis and inflammation: emerging insights

Prostate cancer remains a significant health concern for men throughout the world. Recently, there has developed an expanding multidisciplinary body of literature suggesting a link between chronic inflammation and prostate cancer. In support of this hypothesis, population studies have found an increased relative risk of prostate cancer in men with a prior history of certain sexually transmitted infections or prostatitis. Furthermore, genetic epidemiological data have implicated germline variants of several genes associated with the immunological aspects of inflammation in modulating prostate cancer risk. The molecular pathogenesis of prostate cancer has been characterized by somatic alterations of genes involved in defenses against inflammatory damage and in tissue recovery. A novel putative prostate cancer precursor lesion, proliferative inflammatory atrophy, which shares some molecular traits with prostate intraepithelial neoplasia and prostate cancer, has been characterized. Here, we review the evidence associating chronic inflammation and prostate cancer and consider a number of animal models of prostate inflammation that should allow the elucidation of the mechanisms by which prostatic inflammation could lead to the initiation and progression of prostate cancer. These emerging insights into chronic inflammation in the etiology of prostate carcinogenesis hold the promise of spawning new diagnostic and therapeutic modalities for men with prostate cancer.

Mechanisms in prostatitis/chronic pelvic pain syndrome

PURPOSE

We reviewed the current literature on mechanisms involved in the pathogenesis of prostatitis/chronic pelvic pain syndrome (CPPS).

MATERIALS AND METHODS

A literature review for the years 1966 to 2003 was performed using the MEDLINE database of the United States National Library of Medicine.

RESULTS

National Institutes of Health categories I and II prostatitis result from identifiable prostatic infections, whereas patients with category IV are asymptomatic. The majority of symptomatic cases are category III or chronic prostatitis (CP)/CPPS. The etiology of CP/CPPS is unknown. The traditional marker of inflammation, namely white blood cells in prostatic fluids, does not correlate with the predominant symptom of pelvic pain. An imbalance toward increased proinflammatory and decreased anti-inflammatory cytokines has been implicated and a few studies have shown some correlation of this with pelvic pain. The imbalance in some men may result from polymorphisms at the cytokine loci. An autoimmune process may be involved and experimental evidence indicates that this can be under hormonal influence. Recent findings include possible defects in the androgen receptor. The prostate may not even be the source of the symptoms. Pelvic pain also correlates with the neurotrophin nerve growth factor implicated in neurogenic inflammation and central sensitization. Finally, psychological stress may produce measurable biochemical changes and influence the other processes. The role of normal prostatic bacterial flora in inciting the inflammatory response has also been reconsidered.

CONCLUSIONS

The symptoms of CP/CPPS appear to result from an interplay between psychological factors and dysfunction in the immune, neurological and endocrine systems.

Matrix metalloproteinases in the pathogenesis of estradiol-induced nonbacterial prostatitis in the lateral prostate lobe of the Wistar rat

Chronic nonbacterial prostatitis develops spontaneously with age in the lateral lobe of the prostate in some strains of rat. Our objective was to examine the role of matrix metalloproteinases (MMP) in the pathogenesis of chronic nonbacterial prostatitis using a chronic estrogen treatment, Wistar rat model (Prostate 12 (1988) 271). Male Wistar rats, 90 days of age (8 rats/group), were castrated and groups were implanted 8 days later with 1 cm silastic tubings containing estradiol 17 beta (E2). Some animals received 5-cm silastic tubings of dihydrotestosterone (DHT) or testosterone (T) on day 22 and all untreated control and experimental animals were sacrificed on day 36 of the protocol. MMP activities were determined by SDS-gelatin-, casein-, and carboxymethyl transferrin-polyacrylamide gel zymography. A light/mild interstitial monocytic infiltration was found in the ventral lobes, but not other lobes, of half of the untreated control rats. This ventral lobe interstitial inflammation was not affected by E2 treatment. A prominent to heavy inflammation, including both intraluminal neutrophil and interstitial monocytic infiltrates, was produced by E2 treatment at a 100% incidence in the lateral lobes. Prominent MMP activities were detected in the lateral lobes of E2-treated rats, including both the active (55 and 81 kDa) and proenzyme (72 and 92 kDa) forms of MMP-2 and MMP-9, respectively. These activities were strongly attenuated by treatment of E2-implanted animals with T, which also reduced inflammation; but they were only weakly affected by DHT given with E2, which did not reduce inflammation. Similarly, DHT treatment of E2-implanted castrated rats restored the wet weight of the lateral lobe, but it did not fully restore secretion volume production, whereas T treatment of estrogenized rats increased lateral lobe wet weight and secretion volume above that of untreated controls. E2 treatment also induced an activity in casein gels of about 27 kDa with properties of MMP-7; that is, molecular mass, inhibition by EDTA, stimulation by heparin sulfate in casein and carboxymethylated transferrin gels. A high molecular weight nonmetalloproteinase activity (>160 kDa) was detected in gelatin gels in the lateral prostate lobe of both treated and untreated control animals. In comparison to the lateral lobe, E2 treatment produced only minimal effects on MMP activities in the ventral and dorsal prostatic lobes. Thus, elevated MMP-2, MMP-7, and MMP-9 activities in lateral lobe prostatitis correlate with leukocyte infiltration in the inflammatory response. These proteinases may help mediate the accompanying epithelial atrophy and tissue damage in this organ.

Effect of vitamin E deficiency on the growth and secretory function of the rat prostatic complex

Increased intake of vitamin E has been suggested to be protective against prostate cancer in men, but the effects of vitamin E on prostate growth and function remain poorly defined. The purpose of this study was to determine the effects of vitamin E deficiency on pubertal growth and maturation of the prostate in the rat. Animals were placed on a vitamin E deficient diet at 28 days of age and were followed for 15 and 26 weeks. Vitamin E deficient rats had a circulating vitamin E level of less than 1% of control animals and experienced a decrease in body and testis weight. The deficiency did not alter the weights of the ventral and dorsal lobes of the prostate. However, there was an increase in weight, DNA, and protein contents of the lateral lobe in control and vitamin E deficient rats from 15 to 26 weeks of treatment, but these increases were significantly lower in vitamin E deficient 26-week treated rats. The volume of secretion per milligram tissue was greater in the ventral than lateral or dorsal lobes. The volume of secretion and activity of the secretory 26 kDa protease in the ventral prostate was lower in vitamin E deficient rats at 15 weeks, but not at 26 weeks of treatment. In contrast, the relative protein content of lateral lobe secretion increased in both control and vitamin E deficient rats from 15 to 26 weeks of treatment. The lateral, but not ventral or dorsal, lobes of both control and vitamin E deficient rats were affected by chronic prostatitis as evidenced by infiltration of inflammatory cells. The lateral lobes also showed markedly elevated activities of the matrix metalloproteinases gelatinase A (MMP-2) and gelatinase B (MMP-9). These data indicate that vitamin E deficiency does not alter the growth of the prostatic lobes, nor the onset and extent of lateral lobe specific prostatitis, but it may delay some differentiated functions such as secretion of specific proteins in the ventral lobe. Thus, the effects of vitamin E in the prostate of the rat appear to be selective.

Chronic prostatitis

PURPOSE OF REVIEW

This review covers recent developments in the classification, epidemiology, aetiology, diagnosis and treatment of patients diagnosed with chronic prostatitis (NIH classification types II, IIIa/IIIb and IV prostatitis) in the period of review (2001-2002).

RECENT FINDINGS

Recent studies highlight some of the problems with the 1995 NIH classification. Epidemiological studies have confirmed that "prostatitis" is common, with a prevalence of 10-15%. Associations of prostatitis include benign prostatic hyperplasia, sexually transmitted disease, lower urinary tract symptoms, stress, and reduced sunlight exposure. Elevated levels of cytokines in the seminal plasma and prostatic secretions have been detected in men with chronic prostatitis compared with normal individuals, suggesting an active inflammatory process in the male genital tract. This inflammatory reaction may be mediated by an adaptive immune response directed against a genital tract antigen(s) (autoimmunity). Increased levels of bacterial 16S ribosomal DNA in the prostates of men with chronic prostatitis compared with controls are compatible with the notion that a bacterial inflammatory event initiates an auto-immune process; however, the role of bacteria in the continuation of symptoms is unknown.

SUMMARY

The aetiology of chronic pelvic pain syndrome is still not certain, although an auto-immune process is favoured. Further research is required to determine the putative auto-antigen, the immune responses of patients, the role of bacteria in the inflammatory process, and the patients' pain response to genitourinary insults. As yet no diagnostic tests (other than to eliminate other pathology) and few treatments for chronic prostatitis can be recommended on the basis of scientific evidence.

Theories of prostatitis etiology

Prostatitis reflects a broad spectrum of prostatic infections, both acute and chronic. Chronic prostatitis, known as National Institutes of Health category III or chronic pelvic pain syndrome, broadly defines a disease that is still poorly understood, and as a consequence, difficult to treat. Typical symptoms include pelvic pain and voiding dysfunction. Infection is often cited as the cause of this condition, despite frequent negative cultures. A close look at the local prostatic microenvironment may yield clues. The role of inflammatory mediators and what stimulates them can point to potential sites of prevention. A genetic link or relationship to other diseases may prove to be part of the cause. Furthermore, a neurologic source, whether anatomic or psychologic, has been strongly debated. Ultimately, it may become clear that chronic prostatitis represents the final common result of a disease that originates from a cascade of multiple stimuli.

Similarities between interstitial cystitis and male chronic pelvic pain syndrome

Few clinical conditions encountered by the urologist cause more patient and clinician frustration than interstitial cystitis and male chronic pelvic pain syndrome, also know as nonbacterial prostatitis. This frustration is fueled by the chronicity of often disabling urogenital (and often associated systemic) symptoms coupled with delayed care, misdiagnosis, and suboptimal clinical responses. Basic research and therapeutic trials for these syndromes have historically taken two separate paths. However, mounting evidence suggests that significant overlap may exist between them in epidemiology, pathophysiology, and even therapy. This discussion reviews some of the common features of these clinical problems and makes a case that they might in fact represent different manifestations of the same disease process.