Molecular classification of benign prostatic hyperplasia: A gene expression profiling study in a rat model

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.

Mechanism of Androgen-Independent Stromal Proliferation in Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a chronic proliferative disease showing stromal-dominant proliferation. However, the detailed proliferation mechanism has remained unclear. Although aging and androgen have been reported as definitive risk factors for BPH, recent studies have focused on the involvement of androgen-independent factors. Androgen-independent factors include ischemia, oxidative stress, metabolic syndrome, infection, autoimmune reactions, and inflammation, with inflammation in BPH tissues playing a central role in the BPH proliferative process. Inflammation in BPH tissues by various factors finally leads to tissue remodeling and stromal proliferation through the wound healing process of the prostate. To elucidate the proliferative mechanism of BPH, a study using whole-genome gene expression analysis in a stromal-dominant BPH rat model was performed and showed that immune response-related pathways and complement classical pathways are activated. Furthermore, expression analysis using this BPH rat model showed that the autoimmune reaction triggered complement pathway activation in the proliferative process of BPH. BPH is a multifactorial disease, and understanding the role of androgen-independent factors including immune responses contributes to elucidating the pathogenesis of BPH. Androgen-independent factors may lead to new therapeutic targets for BPH, and further development of this research is expected.

The effect of 5-α reductase inhibitor on Th1, Th2, and Th17 cell-related inflammatory response in BPH

OBJECTIVE

To investigate the effect of 5-α reductase inhibitor on the expression of inflammation-related cytokines in Benign prostatic hyperplasia (BPH) specimens after transurethral prostatic resection (TUR-P).

METHODS

We prospectively examined the expression of inflammation-related cytokines with immunohistochemistry in the paraffin blocks of 60 patients who underwent TUR-P. 30 cases in the 5-α-reductase inhibitor group were treated with finasteride, 5 mg qd, for more than 6 months; 30 cases in the control group were not treated with medicine before operation. HE staining was used to analyze the difference of inflammation reaction between the two groups, and immunohistochemical staining was used to analyze the effect of 5-α reductase inhibitor on the expression of B-cell lymphoma-2 (Bcl-2), Interleukin-2 (IL-2), Interferon-γ (IFN-γ), Interleukin-4 (IL-4), Interleukin-6 (IL-6), Interleukin-17 (IL-17), Interleukin-21 (IL-21) and Interleukin-23 (IL-23) in prostatic tissue.

RESULTS

There was no statistical difference in the location, range and degree of inflammation between the two groups (P > 0.05). When IL-17 expression was low, there was statistical difference between the two groups (P < 0.05). Bcl-2 expression was positively correlated with IL-2, IL-4, IL-6 and IFN-γ (P < 0.05). There was no statistical difference in the expression of IL-21, IL-23 and high expression of IL-17 between the two groups (P > 0.05).

CONCLUSIONS

5-α Reductase inhibitor can inhibit the expression of Bcl-2 in prostatic tissue and the inflammatory response related to T-helper cell 1 (Th1) and T-helper cell 2 (Th2) cells. However, it did not affect Th17 cell-related inflammatory response.

A Novel Insight into the Immune-Related Interaction of Inflammatory Cytokines in Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a common male condition that impacts many men's quality of life by generating lower urinary tract symptoms (LUTS). In recent years, inflammation has become very common in the prostate, and BPH with inflammation has a higher International Prostate Symptom Score (IPSS) score and an enlarged prostate. Chronic inflammation leads to tissue damage and the release of pro-inflammatory cytokines, which play an important role in the pathogenesis of BPH. We will focus on current advancements in pro-inflammatory cytokines in BPH, as well as the future of pro-inflammatory cytokine research.

Discovering pathways in benign prostate hyperplasia: A functional genomics pilot study

Benign prostate hyperplasia (BPH) is one of the well-known urological neoplasms common in males with an increasing number of associated deaths in aging males. It causes uncomfortable urinary symptoms, including urine flow blockage, and may cause bladder, urinary tract or kidney problems. The histopathological and clinical knowledge regarding BPH is limited. In the present study, an in silico approach was applied that uses genome-scale microarray expression data to discover a wide range of protein-protein interactions in addition to focusing on specific genes responsible for BPH to develop prognostic biomarkers. Various genes that were differentially expressed in BPH were identified. Gene and functional annotation clusters were determined and an interaction analysis with disease phenotypes of BPH was performed, as well as an RNA tissue specificity analysis. Furthermore, a molecular docking study of certain short-listed gene biomarkers, namely anterior gradient 2 (AGR2; PDB ID: 2LNT), steroid 5α-reductase 2 (PDB ID: 6OQX), zinc finger protein 3 (PDB ID: 5T00) and collagen type XII α1 chain (PDB ID: 1U5M), was performed in order to identify alternative Chinese herbal agents for the treatment of BPH. Data from the present study revealed that AGR2 receptor (PDB ID: 2LNT) and berberine (Huang Bo) form the most stable complex and therefore may be assessed in further pharmacological studies for the treatment of BPH.

Animal models of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms are common clinical concerns that affect aging men all over the world. The underlying molecular and cellular mechanisms remain elusive. Over the past few years, a number of animal models of BPH, including spontaneous model, BPH-induction model, xenograft model, metabolic syndrome model, mechanical obstruction model, and transgenic model, have been established that may provide useful tools to fill these critical knowledge gaps. In this review, we therefore outlined the present status quo for animal models of BPH, comparing the pros and cons with respect to their ability to mimic the etiological, histological, and clinical hallmarks of BPH and discussed their applicability for future research.

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.

Complement activation by autoantigen recognition in the growth process of benign prostatic hyperplasia

The pathophysiology of benign prostatic hyperplasia (BPH) remained unclear. Here, we concentrated on the complement activation in the growth of BPH using a rat model. BPH tissues were harvested from rats after rat urogenital sinus implantation. The local expression and deposition levels of C1q, C3, mannose-binding lectin (MBL), factor B (FB), and C5b-9 in the rat and human BPH tissues were analyzed by real-time RT-PCR, western blotting and immunohistochemistry (IHC). Serum IgG levels in the rat BPH model were analyzed by ELISA, and IHC was used to assess tissue localization. Proteins binding serum IgG autoantibody in the BPH rats were isolated by immunoprecipitation. C1q, C3, MBL, FB and C5b-9 were highly localized in rat BPH tissues compared to normal tissues. In contrast, C3, FB and C5b-9, but not C1q and MBL, were abundantly detected in human BPH tissues compared to normal tissues. Diffuse localization of IgG in rat BPH tissues was found. Heat shock protein 90, annexin, α-smooth muscle actin, and β-actin were identified as targets for IgG autoantibodies in the BPH model. Our results strongly suggested the role for complement activation in the growth process of BPH, likely triggered by classical pathway activation with autoantibodies.