Relative and total volume of histological components in benign prostatic hyperplasia: relationships between histological components and clinical findings

The activated complement pathway in the fibrous process of benign prostatic hyperplasia

BACKGROUND

To elucidate the changes in activated complement pathway in the fibrous process of benign prostatic hyperplasia (BPH), we analyzed the correlation between complement component expression and histological types of fibrosis using human BPH tissue.

METHODS

Fifty-six histological BPH patients who underwent prostate needle biopsy at our institution (mean age 68.6 ± 6.5 years), divided into two histological groups, fibromuscular and fibrous, were compared. Inflammatory cell infiltration in BPH tissue was evaluated by immunohistochemical staining using CD45, with complement expression analysis performed using C3, factor B, and C5b-9 antibody, and the occupancy ratio of the stained region was calculated. Further, correlation between the histological types of fibrous components in BPH tissue and lower urinary tract symptoms questionnaires was analyzed.

RESULTS

Twenty-seven (48.2%) and 29 (51.8%) cases were classified in the fibromuscular and fibrous groups, respectively. The proportion of CD45-positive cells in BPH tissue was significantly higher in the fibromuscular group. In complement component analysis, factor B did not significantly differ between groups, while C3 (fibromuscular group; 10.7 ± 8.2%, fibrous group; 16.4 ± 12.7%) and C5b-9 (fibromuscular group; 15.9 ± 6.2%, fibrous group; 17.6 ± 9.2%) were significantly higher in the fibrous group (p = 0.04, p = 0.04, respectively). International Prostate Symptom Score Q5 subscore, indicating slow stream, was significantly higher in the fibrous group (p = 0.04).

CONCLUSIONS

In fibrous BPH with abundant fibrosis, the late complement pathway in addition to alternative pathway was activated compared to fibromuscular BPH. These results suggested that the alternative and late complement pathways were involved in the histological fibrous process of BPH.

Development of Tough Hydrogel Phantoms to Mimic Fibrous Tissue for Focused Ultrasound Therapies

Tissue-mimicking gels provide a cost-effective medium to optimize histotripsy treatment parameters with immediate feedback. Agarose and polyacrylamide gels are often used to evaluate treatment outcomes as they mimic the acoustic properties and stiffness of a variety of soft tissues, but they do not exhibit high toughness, a characteristic of fibrous connective tissue. To mimic pathologic fibrous tissue found in benign prostate hyperplasia (BPH) and other diseases that are potentially treatable with histotripsy, an optically transparent hydrogel with high toughness was developed that is a hybrid of polyacrylamide and alginate. The stiffness was established using shear wave elastography (SWE) and indentometry techniques and was found to be representative of human BPH ex vivo prostate tissue. Different phantom compositions and excised ex vivo BPH tissue samples were treated with a 700-kHz histotripsy transducer at different pulse repetition frequencies. Post-treatment, the hybrid gels and the tissue samples exhibited differential reduction in stiffness as measured by SWE. On B-mode ultrasound, partially treated areas were present as hyperechoic zones and fully liquified areas as hypoechoic zones. Phase contrast microscopy of the gel samples revealed liquefaction in regions consistent with the target lesion dimensions and correlated to findings identified in tissue samples via histology. The dose required to achieve liquefaction in the hybrid gel was similar to what has been observed in ex vivo tissue and greater than that of agarose of comparable or higher Young's modulus by a factor >10. These results indicate that the developed hydrogels closely mimic elasticities found in BPH prostate ex vivo tissue and have a similar response to histotripsy treatment, thus making them a useful cost-effective alternative for developing and evaluating different treatment protocols.

Morphological change and characteristics of myofibroblasts during the growth process of benign prostatic hyperplasia

OBJECTIVES

To clarify the morphological change and characteristics of myofibroblast during the growth process of benign prostatic hyperplasia.

METHODS

This study examined the characteristics of myofibroblasts during the growth process of the prostate in the stromal component-dominant benign prostatic hyperplasia rat model. Transforming growth factor-β1 and insulin-like growth factor-binding protein 3 expression were evaluated by western blotting (n = 6). We used double immunohistochemical staining to evaluate the number of myofibroblasts positive for α-smooth muscle actin and vimentin in benign prostatic hyperplasia tissues. Expression and histological analyses of the benign prostatic hyperplasia were also carried out in rats at 2, 3 and 8 weeks after urogenital sinus implantation (n = 6). To evaluate the fine morphological characteristics of myofibroblasts in human benign prostatic hyperplasia tissues, electron microscopy analysis was additionally carried out.

RESULTS

There was a significant upregulation of the transforming growth factor-β1 and insulin-like growth factor-binding protein 3 expression in benign prostatic hyperplasia (P < 0.05). There was a significant increase in the number of myofibroblasts in benign prostatic hyperplasia (P < 0.05) compared with normal prostate, with these abundantly located in the stromal area. The transforming growth factor-β1 and insulin-like growth factor-binding protein 3 expression and number of myofibroblasts showed a time-dependent increase (P < 0.05), with growth factor expressions preceding the myofibroblast increase. Electron microscopy confirmed that the myofibroblast progenitor cells, which possess abundant stress fibers, were predominantly located around fibrous areas in human benign prostatic hyperplasia.

CONCLUSIONS

Differentiation into myofibroblasts induced by transforming growth factor-β1 and insulin-like growth factor-binding protein 3 actively occurs during the growth process of benign prostatic hyperplasia. Myofibroblast progenitor cells seem to be associated with prostatic fibrosis in human benign prostatic hyperplasia.

Role of Stromal Paracrine Signals in Proliferative Diseases of the Aging Human Prostate

Androgens are essential for the development, differentiation, growth, and function of the prostate through epithelial–stromal interactions. However, androgen concentrations in the hypertrophic human prostate decrease significantly with age, suggesting an inverse correlation between androgen levels and proliferative diseases of the aging prostate. In elderly males, age- and/or androgen-related stromal remodeling is spontaneously induced, i.e., increased fibroblast and myofibroblast numbers, but decreased smooth muscle cell numbers in the prostatic stroma. These fibroblasts produce not only growth factors, cytokines, and extracellular matrix proteins, but also microRNAs as stromal paracrine signals that stimulate prostate epithelial cell proliferation. Surgical or chemical castration is the standard systemic therapy for patients with advanced prostate cancer. Androgen deprivation therapy induces temporary remission, but the majority of patients eventually progress to castration-resistant prostate cancer, which is associated with a high mortality rate. Androgen deprivation therapy-induced stromal remodeling may be involved in the development and progression of castration-resistant prostate cancer. In the tumor microenvironment, activated fibroblasts stimulating prostate cancer cell proliferation are called carcinoma-associated fibroblasts. In this review, we summarize the role of stromal paracrine signals in proliferative diseases of the aging human prostate and discuss the potential clinical applications of carcinoma-associated fibroblast-derived exosomal microRNAs as promising biomarkers.

Aberrant Transforming Growth Factor-β Activation Recruits Mesenchymal Stem Cells During Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the overgrowth of prostate tissues with high prevalence in older men. BPH pathogenesis is not completely understood, but it is believed to be a result of de novo overgrowth of prostatic stroma. In this study, we show that aberrant activation of transforming growth factor‐β (TGF‐β) mobilizes mesenchymal/stromal stem cells (MSCs) in circulating blood, which are recruited for the prostatic stromal hyperplasia. Elevated levels of active TGF‐β were observed in both a phenylephrine‐induced prostatic hyperplasia mouse model and human BPH tissues. Nestin lineage tracing revealed that 39.6% ± 6.3% of fibroblasts and 73.3% ± 4.2% smooth muscle cells were derived from nestin⁺ cells in Nestin‐Cre, Rosa26‐YFP^flox/+mice. Nestin⁺ MSCs were increased in the prostatic hyperplasia mice. Our parabiosis experiment demonstrate that nestin⁺ MSCs were mobilized and recruited to the prostatic stroma of wild‐type mice and gave rise to the fibroblasts. Moreover, injection of a TGF‐β neutralizing antibody (1D11) inhibits mobilization of MSCs, their recruitment to the prostatic stroma and hyperplasia. Importantly, knockout of TβRII in nestin⁺ cell lineage ameliorated stromal hyperplasia. Thus, elevated levels of TGF‐β‐induced mobilization and recruitment of MSCs to the reactive stroma resulting in overgrowth of prostate tissues in BPH and, thus, inhibition of TGF‐β activity could be a potential therapy for BPH. Stem Cells Translational Medicine2017;6:394–404

Intermediate-conductance Ca2+-activated K+ channel, KCa3.1, as a novel therapeutic target for benign prostatic hyperplasia

Recently, a new experimental stromal hyperplasia animal model corresponding to clinical benign prostatic hyperplasia (BPH) was established. The main objective of this study was to elucidate the roles of the intermediate-conductance Ca(2+)-activated K(+) channel (K(Ca)3.1) in the implanted urogenital sinus (UGS) of stromal hyperplasia BPH model rats. Using DNA microarray, real-time polymerase chain reaction, Western blot, and/or immunohistochemical analyses, we identified the expression of K(Ca)3.1 and its transcriptional regulators in implanted UGS of BPH model rats and prostate needle-biopsy samples and surgical prostate specimens of BPH patients. We also examined the in vivo effects of a K(Ca)3.1 blocker, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), on the proliferation index of implanted UGS by measurement of UGS weights and proliferating cell nuclear antigen immunostaining. K(Ca)3.1 genes and proteins were highly expressed in implanted UGS rather than in the normal host prostate. In the implanted UGS, the gene expressions of two transcriptional regulators of K(Ca)3.1, repressor element 1-silencing transcription factor and c-Jun, were significantly down- and up-regulated, and the regulations were correlated negatively or positively with K(Ca)3.1 expression, respectively. Positive signals of K(Ca)3.1 proteins were detected exclusively in stromal cells, whereas they were scarcely immunolocalized to basal cells of the epithelium in implanted UGS. In vivo treatment with TRAM-34 significantly suppressed the increase in implanted UGS weights compared with the decrease in stromal cell components. Moreover, significant levels of K(Ca)3.1 expression were observed in human BPH samples. K(Ca)3.1 blockers may be a novel treatment option for patients suffering from BPH.

Structural changes in alpha1-adrenoceptor antagonist-treated human prostatic stroma

Alpha1-adrenoceptor antagonists (alpha1-blockers) are currently used as first-line drugs for the treatment of benign prostatic hyperplasia (BPH). However, cases of BPH are often encountered in which the efficacy of alpha1-blockers decreases and switching to surgical treatment is required. One factor responsible for this resistance includes structural changes in prostatic tissue architecture following repeated oral administration of alpha1-blockers. Forty patients suspected of having prostate cancer, but without evidence of malignancy on prostatic biopsy were divided into two groups: an untreated group (n = 17) and an oral alpha1-blocker-treated group (n = 23). Twenty-one patients exhibiting resistance to oral alpha1-blocker therapy who underwent surgery were assigned into the surgically treated group. Each tissue sample was subjected to Masson's trichrome staining to distinguish collagen fibers from smooth muscle constituting prostatic stroma. The mean collagen fiber share was 62.2 +/- 10.4% in the untreated group, 72.1 +/- 9.1% in the oral alpha1-blocker-treated group, and 72.2 +/- 15.7% in the surgically treated group. Focusing on cases exhibiting high-collagen fiber share (70% or more), the distribution in each of the two alpha1-blocker-treated groups (16 of the 23 cases from the oral alpha1-blocker-treated group and 10 of the 21 cases from the surgically treated group) differed significantly from that in the untreated group (2 of the 17 cases). Our findings suggest that the accumulation of collagen fibers in prostatic stroma could be one of the factors responsible for alpha1-blocker treatment.

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.

Benign Prostatic Hyperplasia: A Review and Ultrasound Classification

Benign prostatic hyperplasia (BPH) is reviewed, including definition,natural history, diagnosis, and brief discussion of clinical management. Transrectal ultrasound is used to demonstrate the gross anatomy and natural history of BPH and its role in diagnosis and treatment strategies. A potentially useful ultrasound classification of BPH based on the gross anatomic classification of Randall is illustrated.

MOLECULAR AND CELLULAR PATHOGENESIS OF BENIGN PROSTATIC HYPERPLASIA

PURPOSE

Symptomatic benign prostatic hyperplasia (BPH) is one of the most common ailments seen by the urologist. Significant advances have occurred in medical and surgical therapy, and in the understanding of the biology of this disease. However, the basic science literature is often conflicting and confusing, without a unified voice. We report the current state of knowledge of the molecular and cellular basis of BPH.

MATERIALS AND METHODS

We compiled and interpreted basic science studies relevant to BPH pathogenesis.

RESULTS

Cellular alterations that include changes in proliferation, differentiation, apoptosis and senescence in the epithelium and stroma are implicated in BPH pathogenesis. Molecular analyses have yielded numerous candidate genes important in disease progression. Differential expression of cytokines and growth factors in BPH tissue suggests roles for inflammation and hypoxia. Through the use of cell culture models the complex regulatory mechanisms of growth control in BPH are becoming defined.

CONCLUSIONS

The scientific endeavor has resulted in great strides in our understanding of BPH on a molecular and cellular level. It is hopeful that basic science and translational research will improve treatment and prevention strategies for this common disease of elderly men.

Volumetric density of elastic and reticular fibers in transition zone of controls and patients with benign prostatic hyperplasia

OBJECTIVES

To analyze the volumetric density (Vv) of elastic and reticular fibers in the transition zone of controls and patients with benign prostatic hyperplasia (BPH).

METHODS

Prostatic tissue samples were obtained from 25 patients (age range 63 to 79 years, mean 68) with clinical symptoms of bladder outlet obstruction who had undergone open prostatectomy. The control group was composed of 25 transition zone samples from prostates obtained during autopsy of adults aged younger than 30 years (killed in accidents). The Vv of the elastic and reticular fibers was determined in 25 random fields per prostate, using the point-count method with an M-42 grid test system. The data were analyzed using the Kolmogorov-Smirnov, Shapiro-Wilk W, and Mann-Whitney U tests. The Vv of these components was determined by stereologic methods.

RESULTS

The Vv in the control and BPH groups was 12.47% +/- 3.6% and 16.55% +/- 9.11% in the elastic system fibers (difference not statistically significant) and 22.75% +/- 1.66% and 29.33% +/- 1.08% in the reticular fibers (difference statistically significant), respectively.

CONCLUSIONS

Reticular fibers showed a statistically significant increase in the BPH samples, and this finding suggests that stromal network fibers play a significant role in BPH.

Prostatic epithelial and luminal area in the transition zone acini: morphometric analysis in normal and hyperplastic human prostate

OBJECTIVE

To analyse quantitatively the acini and changes in the acinar epithelium and lumen in the transitional zone of normal and hyperplastic human prostates.

PATIENTS AND METHODS

Tissue samples of the transitional zone were taken from prostates with benign prostatic hyperplasia (BPH) obtained from 20 patients with clinical symptoms of bladder outlet obstruction who underwent open prostatectomy. The control tissue comprised 20 transitional zones of prostates obtained during autopsy of adults aged < 30 years (killed in accidents). The following variables were measured; the number of acini, total acinar area, area of the lumen, epithelial area, and the median (range) epithelial height, using computerized histomorphometric techniques.

RESULTS

The total area of the acini and the luminal area was statistically significantly greater in BPH. In normal and hyperplastic prostates, respectively, the total mean (sd) area (mm2) of the acini was 0.041 (0.007) and 0.056 (0.016), of the lumen was 0.016 (0.003) and 0.036 (0.013), and of the epithelium was 0.025 (0.004) and 0.019 (0.003) (all P < 0.001). There was no statistically significant difference in the number of acini between controls and BPH. The area and the height of the acinar epithelium was statistically significantly greater in BPH; for epithelial height ( micro m) in normal and BPH tissue, respectively the minimum height was 9.92 (1.67) and 6.45 (1.14), the maximum 54.38 (4.09) and 41.52 (4.51) and the median 27.89 (2.48) and 19.96 (2.20) (all P < 0.001).

CONCLUSIONS

There was no significant difference in the number of acini between control and BPH tissue, but the area and the height of the acinar epithelium was significantly lower in BPH.

Stromal and acinar components of the transition zone in normal and hyperplastic human prostate

OBJECTIVE

To analyse the histological components of the transition zone in both normal human prostate and benign prostatic hyperplasia (BPH), and to determine the volumetric density (Vv) of the different elements (connective tissue, smooth muscle cells, acini and total stroma).

MATERIALS AND METHODS

Samples of BPH tissue from the transition zone were obtained from 16 patients with clinical symptoms of bladder outlet obstruction who underwent open prostatectomy. The control samples comprised 16 transition zone samples from prostates obtained during necropsy of adults aged < 30 years (killed in accidents). The Vv of these components was determined by stereological methods.

RESULTS

The mean (sd) Vv in the controls and BPH samples were, respectively: connective tissue 40.47 (5.16) and 46.71 (9.91)%; smooth muscle cells 24.86 (2.74) and 31.56 (5.49)%; acini 28.73 (6.25) and 17.78 (10.87)%; all differences were statistically significant.

CONCLUSIONS

These results confirm the hypothesis that in BPH there is an increase in the stromal component, both smooth muscle fibres and connective tissue.