Changes in erectile organ structure and function in a rat model of chronic prostatitis/chronic pelvic pain syndrome

Evaluation of psychological stress, cortisol awakening response, and heart rate variability in patients with chronic prostatitis/chronic pelvic pain syndrome complicated by lower urinary tract symptoms and erectile dysfunction

BACKGROUND

Mental stress and imbalance of its two neural stress systems, the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis, are associated with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and erectile dysfunction (ED). However, the comprehensive analyses of psychological stress and stress systems are under-investigated, particularly in CP/CPPS patients complicated by lower urinary tract symptoms (LUTS) and ED.

MATERIALS AND METHODS

Participants were 95 patients in CP/CPPS+ED group, 290 patients in CP/CPPS group, 124 patients in ED group and 52 healthy men in control group. The National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI), the International Index of Erectile Function-5 (IIEF-5) and the International Prostate Symptom Score (IPSS) were used for assessing the disease severity of CP/CPPS, LUTS and ED. Psychometric self-report questionnaires including the Beck Anxiety Inventory (BAI), Perceived Stress Scale (PSS), Type A Personality Test (TAPT) and Symptom Checklist 90 (SCL-90) were completed for distress from physical symptoms. Twenty-five subjects per group were randomly selected for further investigating the changes of the HPA axis and ANS. Saliva samples were taken on 3 consecutive days at 8 specific times with strict reference to time of morning awakening for evaluation of free cortisol. Heart rate variability (HRV) as marker of the ANS was measured using 24 h electrocardiography, and time-and frequency-domain variables were analyzed.

RESULTS

The BAI and SCL-90 scores were significantly higher in the CP/CPPS+ED, CP/CPPS and ED groups compared with the control group (p < 0.01). The PSS scores of both groups with ED were significantly higher than the control group (p < 0.01). Compared with the CP/CPPS group, the differences of PSS, SCL-90 and TAPT scores were statistically significant in CP/CPPS+ED patients (p < 0.01). The IPSS scores were shown to have significantly positive correlations with BAI (r = 0.32, p < 0.0001), PSS (r = 0.18, p < 0.01) and SCL-90 (r = 0.19, p < 0.01) in the CP/CPPS patients. However, in all subjects, the IIEF-5 scores were shown to have significantly negative correlations with BAI (r = -0.17，p < 0.001), PSS (r = -0.25，p < 0.0001), SCL-90 (r = -0.20，p < 0.001) and quality of life score in NIH-CPSI (r = -0.14，p = 0.0075). Cortisol awakening response (CAR) parameters and diurnal cortisol levels did not significantly vary between the four groups. Time-dependent parameters of HRV also did not differ significantly across groups. In the frequency domain analysis, low frequency (LF) was significantly lower in ED patients when compared with CP/CPPS+ED patients (p = 0.044) and healthy controls (p = 0.005), high frequency (HF) power was significantly higher in healthy controls compared to patients with ED (p < 0.001), CP/CPPS (p < 0.001) and CP/CPPS+ED (p < 0.001), and the CP/CPPS+ED group had significantly higher LF/HF ratio than the control group (p = 0.001).

CONCLUSION

CP/CPPS and ED patients score exceedingly high on most psychosocial variables. The symptom scores of LUTS and ED positively correlate with the severity of psychological stress. Our findings also suggest that the ANS sympathovagal imbalance is associated with ED and LUTS in CP/CPPS, whereas HPA axis activity is not.

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.

Structural and functional abnormalities of penile cavernous endothelial cells result in erectile dysfunction at experimental autoimmune prostatitis rat

Background

There is growing recognition of the association of CP/CPPS accompany with ED. However, the specific mechanism of action remains unclear. The aim of this study was to investigate structural and functional abnormalities of cavernous endothelial cells in EAP rat, which may result in the ED.

Methods

we use rat prostate protein extract supplemented with immunoadjuvant to induce EAP rat, ICP and MAP were measured and inflammatory factor infiltration, Akt, eNOS, AR, nNOS and iNOS in the corpus cavernosum were tested. Subsequently, the normal rat and EAP rat cavernosum endothelial cells were purified by MACS, and the metabolism, oxidative stress, MMP, Akt, eNOS, AR and iNOS were evaluated.

Results

The EAP rat model was successfully constructed. The ratio of max ICP/MAP in EAP rat was significantly lower and TNF-α infiltration in corpus cavernosum was significantly higher than normal rats. Besides, Akt, eNOS and AR were decreased, iNOS was significantly increased. The growth and metabolism of endothelial cells in the EAP rats corpus cavernosum decreased and inflammatory factor mRNA was increased and intracellular oxidative stress was also increased significantly. The MMP of EAP rats cavernosum endothelial cells decreased and the expression of Akt, eNOS and AR were also significantly decreased, iNOS was significantly increased.

Conclusion

The prostate suffer local inflammatory infiltrate and promotes cytokines infiltrated into corpus cavernosum caused the oxidative stress increases and the metabolism or MMP decreases. In addition, AR, Akt and eNOS expression and phosphorylation are also reduced, thereby inhibiting the diastolic function of the corpus cavernosum, resulting in decreased erectile function.

Effect of tadalafil on chronic pelvic pain and prostatic inflammation in a rat model of experimental autoimmune prostatitis

BACKGROUND

Experimental autoimmune prostatitis (EAP) shares important clinical features with clinical chronic prostatitis/chronic pelvic pain. We investigated the effect of tadalafil on pelvic pain and prostatic inflammation in a rat EAP model.

METHODS

EAP was induced in rats by intradermal injection of rat prostate antigen and complete Freund's adjuvant on days 0 and 28. Rats were treated with tadalafil (2 mg/kg, p.o.; EAP-tadalafil) or vehicle (EAP-vehicle) once daily from day 0, while sham-operated animals were treated with vehicle only (Sham). Tactile allodynia was measured on days 28, 35, and 42 by applying von Frey filaments to the lower abdomen as an index of pelvic pain. On day 42, the plasma immunoglobulin G (IgG) concentration and the testosterone/estradiol ratio were measured and histopathological analysis of the prostate was performed.

RESULTS

Tactile allodynia in the pelvic region was observed on days 28, 35, and 42 after EAP induction. The tactile allodynia observed on day 42 was significantly reduced by repeated treatment with tadalafil. Plasma IgG concentrations increased after EAP induction but the increase was not changed by tadalafil treatment. Prostate tissues were characterized by epithelial necrosis, infiltration of neutrophils and/or lymphocytes to acini and stroma, and fibrosis, in addition to a high stroma-to-epithelium ratio. Tadalafil treatment significantly suppressed the severity of the lesions.

CONCLUSIONS

EAP rats developed pelvic pain, prostatic inflammation and increased plasma IgG concentrations. Tadalafil inhibited the chronic pelvic pain and prostatic inflammation, suggesting that its anti-inflammatory action may contribute to its blocking of pain development in the EAP model.

Identification and preliminary study of immunogens involved in autoimmune prostatitis in human males

BACKGROUND

Experimental models have confirmed that autoimmunity is an important factor in the onset of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS); however, there is no conclusive evidence on whether autoimmune prostatitis exists in human males.

METHODS

Rabbits were immunized with either human prostate tissue homogenates or normal saline and the antiserum was collected. Two-dimensional electrophoresis (2-DE) was performed on the homogenates and Western blotting was conducted on the sera. The identified human prostate tissue immunodominant antigens (HPTIAs) were detected by mass spectrometry. The serum immunoglobulin (Ig)G from the immunized rabbits was purified with protein A-agarose, and the purified IgG was linked with Sepharose to purify HPTIAs by affinity chromatography. Non-obese diabetic (NOD) mice were immunized with the purified HPTIAs, and the levels of serum antibodies, INF-γ, and histopathological changes in their prostate tissues were detected. The purified HPTIAs were coated into polystyrene pores and serum autoantibodies in CP/CPPS patients were detected by enzyme-linked immunosorbent assay (ELISA). Meanwhile, serum interleukin 2 (IL-2), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNFα) levels in CP/CPPS patients were also determined by ELISA.

RESULTS

Sixteen HPTIAs were identified. Among them, three types were reported to be associated with prostatic diseases. Prostatitis was induced in mice immunized with the 16-HPTIA complex, with positive serum autoantibody and increased prostatic IFN-γ levels. The positive rate of serum autoantibodies against HPTIAs was significantly higher in CP/CPPS patients (23.1%, 18/78) than in the control (2.7%, 2/75). But there was no significant difference in serum TNFα, IFNγ, and IL-2 levels between the CPPS patients with positive and negative autoantibodies against HPTIAs.

CONCLUSIONS

Autoantibodies against HPTIAs exist in part in CP/CPPS patients, which implies that autoimmunity and the 16 HPTIAs are important factors in the onset of CP/CPPS. The detection of serum autoantibodies could be applied in clinical diagnoses of autoimmune prostatitis; treatment protocols might change. Additional studies are needed to determine which of the 16 HPTIAs is the most important.