Obesity-induced mouse benign prostatic hyperplasia (BPH) is improved by treatment with resveratrol: implication of oxidative stress, insulin sensitivity and neuronal growth factor

Capsaicin reduces blood glucose and prevents prostate growth by regulating androgen, RAGE/IGF-1/Akt, TGF-β/Smad signalling pathway and reversing epithelial-mesenchymal transition in streptozotocin-induced diabetic mice

Type 2 diabetes mellitus (T2DM) is a metabolic disease. Diabetes increases the risk of benign prostatic hyperplasia (BPH). Capsaicin is extracted from chili peppers and possesses many pharmacological properties, including anti-diabetic, pain-relieving, and anti-cancer properties. This study aimed to investigate the effects of capsaicin on glucose metabolism and prostate growth in T2DM mice and uncover the related mechanisms. Mice model of diabetes was established by administering a high-fat diet and streptozotocin. Oral administration of capsaicin for 2 weeks inhibited prostate growth in testosterone propionate (TP)-treated mice. Furthermore, oral administration of capsaicin (5 mg/kg) for 2 weeks decreased fasting blood glucose, prostate weight, and prostate index in diabetic and TP-DM mice. Histopathological alterations were measured using hematoxylin & eosin (H&E) staining. The protein expression of 5α-reductase type II, androgen receptor (AR), and prostate-specific antigen (PSA) were upregulated in diabetic and TP-DM mice, but capsaicin reversed these effects. Capsaicin decreased the protein expression of p-AKT, insulin-like growth factor-1 (IGF-1), IGF-1R, and the receptor for advanced glycation end products (RAGE) in diabetic and TP-DM mice. Capsaicin also regulated epithelial-mesenchymal transition (EMT) and modulated the expression of fibrosis-related proteins, including E-cadherin, N-cadherin, vimentin, fibronectin, α-SMA, TGFBR2, TGF-β1, and p-Smad in TP-DM mice. In this study, capsaicin alleviated diabetic prostate growth by attenuating EMT. Mechanistically, capsaicin affected EMT by regulating RAGE/IGF-1/AKT, AR, and TGF-β/Smad signalling pathways. These results provide with new therapeutic approach for treating T2DM or T2DM-induced prostate growth.

Targeting NADPH Oxidase as an Approach for Diabetic Bladder Dysfunction

Diabetic bladder dysfunction (DBD) is the most prevalent complication of diabetes mellitus (DM), affecting >50% of all patients. Currently, no specific treatment is available for this condition. In the early stages of DBD, patients typically complain of frequent urination and often have difficulty sensing when their bladders are full. Over time, bladder function deteriorates to a decompensated state in which incontinence develops. Based on studies of diabetic changes in the eye, kidney, heart, and nerves, it is now recognized that DM causes tissue damage by altering redox signaling in target organs. NADPH oxidase (NOX), whose sole function is the production of reactive oxygen species (ROS), plays a pivotal role in other well-known and bothersome diabetic complications. However, there is a substantial gap in understanding how NOX controls bladder function in health and the impact of NOX on DBD. The current review provides a thorough overview of the various NOX isoforms and their roles in bladder function and discusses the importance of further investigating the role of NOXs as a key contributor to DBD pathogenesis, either as a trigger and/or an effector and potentially as a target.

Methylglyoxal and Advanced Glycation End Products (AGEs): Targets for the Prevention and Treatment of Diabetes-Associated Bladder Dysfunction?

Methylglyoxal (MGO) is a highly reactive α-dicarbonyl compound formed endogenously from 3-carbon glycolytic intermediates. Methylglyoxal accumulated in plasma and urine of hyperglycemic and diabetic individuals acts as a potent peptide glycation molecule, giving rise to advanced glycation end products (AGEs) like arginine-derived hydroimidazolone (MG-H1) and carboxyethyl-lysine (CEL). Methylglyoxal-derived AGEs exert their effects mostly via activation of RAGE, a cell surface receptor that initiates multiple intracellular signaling pathways, favoring a pro-oxidant environment through NADPH oxidase activation and generation of high levels of reactive oxygen species (ROS). Diabetic bladder dysfunction is a bothersome urological complication in patients with poorly controlled diabetes mellitus and may comprise overactive bladder, urge incontinence, poor emptying, dribbling, incomplete emptying of the bladder, and urinary retention. Preclinical models of type 1 and type 2 diabetes have further confirmed the relationship between diabetes and voiding dysfunction. Interestingly, healthy mice supplemented with MGO for prolonged periods exhibit in vivo and in vitro bladder dysfunction, which is accompanied by increased AGE formation and RAGE expression, as well as by ROS overproduction in bladder tissues. Drugs reported to scavenge MGO and to inactivate AGEs like metformin, polyphenols, and alagebrium (ALT-711) have shown favorable outcomes on bladder dysfunction in diabetic obese leptin-deficient and MGO-exposed mice. Therefore, MGO, AGEs, and RAGE levels may be critically involved in the pathogenesis of bladder dysfunction in diabetic individuals. However, there are no clinical trials designed to test drugs that selectively inhibit the MGO-AGEs-RAGE signaling, aiming to reduce the manifestations of diabetes-associated bladder dysfunction. This review summarizes the current literature on the role of MGO-AGEs-RAGE-ROS axis in diabetes-associated bladder dysfunction. Drugs that directly inactivate MGO and ameliorate bladder dysfunction are also reviewed here.

Periprostatic adipose tissue (PPAT) supernatant from obese mice releases anticontractile substances and increases human prostate epithelial cell proliferation: the role of nitric oxide and adenosine

Background: The prostate gland is surrounded by periprostatic adipose tissue (PPAT) that can release mediators that interfere in prostate function. In this study, we examined the effect of periprostatic adipose tissue supernatant obtained from obese mice on prostate reactivity in vitro and on the viability of human prostatic epithelial cell lines. Methods: Male C57BL/6 mice were fed a standard or high-fat diet after which PPAT was isolated, incubated in Krebs-Henseleit solution for 30 min (without prostate) or 60 min (with prostate), and the supernatant was then collected and screened for biological activity. Total nitrate and nitrite (NOx^-) and adenosine were quantified, and the supernatant was then collected and screened for biological activity. NOx^- and adenosine were quantified. Concentration-response curves to phenylephrine (PE) were obtained in prostatic tissue from lean and obese mice incubated with or without periprostatic adipose tissue. In some experiments, periprostatic adipose tissue was co-incubated with inhibitors of the nitric oxide (NO)-cyclic guanosine monophosphate pathway (L-NAME, 1400W, ODQ), adenylate cyclase (SQ22536) or with adenosine A_2A (ZM241385), and A_2B (MRS1754) receptor antagonists. PNT1-A (normal) and BPH-1 (hyperplasic) human epithelial cells were cultured and incubated with supernatant from periprostatic adipose tissue for 24, 48, or 72 h in the absence or presence of these inhibitors/antagonists, after which cell viability and proliferation were assessed. Results: The levels of NOx^- and adenosine were significantly higher in the periprostatic adipose tissue supernatant (30 min, without prostate) when compared to the vehicle. A trend toward an increase in the levels of NOX was observed after 60 min. PPAT supernatant from obese mice significantly reduced the PE-induced contractions only in prostate from obese mice. The co-incubation of periprostatic adipose tissue with L-NAME, 1400W, ODQ, or ZM241385 attenuated the anticontractile activity of the periprostatic adipose tissue supernatant. Incubation with the supernatant of periprostatic adipose tissue from obese mice significantly increased the viability of PNT1-A cells and attenuated expression of the apoptosis marker protein caspase-3 when compared to cells incubated with periprostatic adipose tissue from lean mice. Hyperplastic cells (BPH-1) incubated with periprostatic adipose tissue from obese mice showed greater proliferation after 24 h, 48 h, and 72 h compared to cells incubated with culture medium alone. BPH-1 cell proliferation in the presence of PPAT supernatant was attenuated by NO-signaling pathway inhibitors and by adenosine receptor antagonists after 72 h. Conclusion: NO and adenosine are involved in the anticontractile and pro-proliferative activities of periprostatic adipose tissue supernatant from obese mice. More studies are needed to determine whether the blockade of NO and/or adenosine derived from periprostatic adipose tissue can improve prostate function.

Selective Pharmacological Inhibition of NOX2 by GSK2795039 Improves Bladder Dysfunction in Cyclophosphamide-Induced Cystitis in Mice

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. Among the many mediators implicated in cystitis, the overproduction of reactive oxygen species (ROS) seems to play a key role, although the main source of ROS remains unclear. This study aimed to investigate the contribution of NADPH oxidase (NOX) isoforms in ROS generation and the voiding dysfunction of cyclophosphamide (CYP, 300 mg/Kg, ip, 24 h)-induced cystitis in adult female mice, a well-recognized animal model to study IC/BPS, by using GKT137831 (5 mg/Kg, ip, three times in a 24 h period) or GSK2795039 (5 mg/Kg, ip, three times in a 24 h period) to inhibit NOX1/4 or NOX2, respectively. Our results showed that treatment with GSK2795039 improved the dysfunctional voiding behavior induced by CYP, reduced bladder edema and inflammation, and preserved the urothelial barrier integrity and tight junction occludin expression, besides inhibiting the characteristic vesical pain and bladder superoxide anion generation. In contrast, the NOX1/4 inhibitor GKT137831 had no significant protective effects. Taken together, our in vivo and ex vivo data demonstrate that NOX2 is possibly the main source of ROS observed in cystitis-induced CYP in mice. Therefore, selective inhibition of NOX2 by GSK2795039 may be a promising target for future therapies for IC/BPS.

Efficacy of resveratrol in male urogenital tract dysfunctions: an evaluation of pre-clinical data

Resveratrol is a polyphenol found naturally in fruits and plants. Recently, studies in humans and animal models have suggested beneficial properties of this polyphenol, such as improvements to metabolic and lipid profiles, along with antioxidant, anti-inflammatory and anti-proliferative effects. In the urogenital tract (UGT), resveratrol has also been tested clinically and experimentally as a therapeutic drug in several diseases; however, the translational efficacy of resveratrol, especially in UGT, is still a matter of debate. In the present review, we address the pre-clinical efficacy of resveratrol in UGT-related dysfunctions, focusing on lower urinary tract symptoms, non-cancerous prostatic disease (benign prostatic hyperplasia and prostatitis) and erectile dysfunction. In vitro studies indicate that resveratrol reduces inflammatory markers and oxidative stress, and improves endothelial function in UGT organs and cells isolated from humans and animals. Despite displaying low oral bioavailability, in vivo administration of resveratrol largely improves erectile dysfunction, benign prostatic hyperplasia, prostatitis and voiding impairments, as evidenced in different animal models. Resveratrol also acts as a microbiota modulator, which may explain some of its beneficial effects in vivo. In contrast to the large amount of pre-clinical data, there are insufficient clinical trials to establish resveratrol treatment efficacy in human UGT-related diseases. In summary, we provide an overview of the in vivo and in vitro efficacy of resveratrol in animal and human UGT dysfunctions, which may support future clinical trials.

Aerobic exercises ameliorate benign prostatic hyperplasia via IGF-1/IGF-1R/ERK/AKT signalling pathway in prostate tissue of high-fat-diet-fed mice with insulin resistance

This study investigated the changes in the prostate of high-fat diet (HFD)-fed mice with insulin resistance (IR) and explored the possible mechanisms of the effects of 8-week treadmill aerobic exercise on prostatic hyperplasia in insulin-resistant mice through the IGF-1/IGF-1R/ERK/AKT signalling pathway. Results showed IR in mice caused an increase in prostate-related indicators, such as prostate weight (PW) and prostate volume (PV), resulting in prostatic hyperplasia. The area of the glandular lumen and the height of the glandular epithelium in mice with IR were increased, which indicating that it caused prostatic hyperplasia through epithelial cell proliferation. In addition, the level of IGF-1 in serum and the expression of IGF-1R, ERK and AKT in prostate tissue of high-fat diet induced IR mice increased significantly, which might be related to the proliferation of prostate cells. However, aerobic exercise lowered the blood sugar, serum insulin and IGF-1; inhibited the combination of IGF-1 and IGF-1R on the prostate; down-regulated the expression of IGF-1R, ERK and AKT proteins; and then suppressed the expression of downstream proliferation genes, thereby achieving the purpose of inhibiting the proliferation of prostate epithelial cells. In conclusion. Eight weeks of aerobic exercise might improve the prostate hyperplasia in mice via down-regulating the serum insulin and IGF-1, thus enhancing the insulin sensitivity of insulin-resistant mice and regulating the IGF-1/IGF-1R/ERK/AKT signalling pathway by inhibiting the expression of IGF-1R, ERK and AKT in the prostate tissue. However, this exercise had no significant effect on PV, PW and prostate index (PI).

The pathological growth of the prostate gland in atherogenic contexts

The human prostate is an androgen-dependent gland where an imbalance in cell proliferation can lead to benign prostatic hyperplasia (BPH), which results in voiding lower urinary tract symptoms in the elderly. In the last decades, novel evidence has suggested that BPH might represent an element into the wide spectrum of disorders conforming the Metabolic Syndrome (MS). The dyslipidemic state and the other atherogenic factors of the MS have been shown to induce, maintain and/or aggravate the pathological growth of different organs, with data regarding the prostate being still limited. We here review the available epidemiological and experimental studies about the association of BPH with dyslipidemias. In particular, we have focused on Oxidized Low-Density Lipoproteins (OxLDL) as a potential trigger for vascular disease and cellular proliferation in atherogenic contexts, analyzing their putative molecular mechanisms, including the induction of specific extracellular vesicles (EVs)-derived miRNAs. In addition to the epidemiological evidence, OxLDL is proposed to play a fundamental role in the upregulation of prostatic cell proliferation by activating the Rho/Akt/p27^Kip1 pathway in atherogenic contexts. miR-21, miR-141, miR-143, miR-145, miR-155, and miR-221 would be involved in the transcription of genes related to the proliferative process. Although much remains to be investigated regarding the impact of OxLDL, its receptors, and molecular mechanisms on the prostate, it is clear that EVs and miRNAs represent a promising target for proliferative pathologies of the prostate gland.

The Role of Periprostatic Adipose Tissue on Prostate Function in Vascular-Related Disorders

The lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) are highly prevalent worldwide. Clinical and experimental data suggest that the incidence of LUTS-BPH is higher in patients with vascular-related disorders such as in pelvic ischemia, obesity and diabetes as well as in the ageing population. Obesity is an important risk factor that predisposes to glucose intolerance, insulin resistance, dyslipidemia, type 2 diabetes mellitus and cardiovascular disorders. Prospective studies showed that obese men are more likely to develop LUTS-BPH than non-obese men. Yet, men with greater waist circumferences were also at a greater risk of increased prostate volume and prostate-specific antigen than men with lower waist circumference. BPH is characterized by an enlarged prostate and increased smooth muscle tone, thus causing urinary symptoms. Data from experimental studies showed a significant increase in prostate and epididymal adipose tissue weight of obese mice when compared with lean mice. Adipose tissues that are in direct contact with specific organs have gained attention due to their potential paracrine role. The prostate gland is surrounded by periprostatic adipose tissue (PPAT), which is believed to play a paracrine role by releasing growth factors, pro-inflammatory, pro-oxidant, contractile and anti-contractile substances that interfere in prostate reactivity and growth. Therefore, this review is divided into two main parts, one focusing on the role of adipokines in the context of obesity that can lead to LUTS/BPH and the second part focusing on the mediators released from PPAT and the possible pathways that may interfere in the prostate microenvironment.

Pharmacological Effects and Potential Clinical Usefulness of Polyphenols in Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is arguably the most common benign disease among men. This disease is often associated with lower urinary tract symptoms (LUTS) in men and significantly decreases the quality of life. Polyphenol consumption reportedly plays an important role in the prevention of many diseases, including BPH. In recent years, in addition to disease prevention, many studies have reported the efficacy and safety of polyphenol treatment against various pathological conditions in vivo and in vitro. Furthermore, numerous studies have also revealed the molecular mechanisms of the antioxidant and anti-inflammatory effects of polyphenols. We believe that an improved understanding of the detailed pharmacological roles of polyphenol-induced activities at a molecular level is important for the prevention and treatment of BPH. Polyphenols are composed of many members, and their biological roles differ. In this review, we first provide information regarding the pathological roles of oxidative stress and inflammation in BPH. Next, the antioxidant and anti-inflammatory effects of polyphenols, including those of flavonoids and non-flavonoids, are discussed. Finally, we talk about the results and limitations of previous clinical trials that have used polyphenols in BPH, with particular focus on their molecular mechanisms of action.

Melatonin ameliorates degenerative alterations caused by age in the rat prostate and mitigates high-fat diet damages

Imbalance of sexual steroids milieu and oxidative stress are often observed during aging and correlated to prostate disorders. Likewise, high-fat intake has been related to prostate damage and tumor development. Melatonin (MLT) is an antioxidant whose secretion decreases in elderly and is also suggested to protect the gland. This study evaluated the impact of a long-term high-fat diet during aging on prostate morphology and antioxidant system of rats and tested the effects of MLT supplementation under these conditions. Male rats were assigned into four groups: control, treated with MLT, high-fat diet and high-fat diet treated with MLT. The high-fat diet was provided from the 24th week of age, MLT from the 48th (100 μg/kg/day) and rats were euthanized at the 62nd week. The high-fat diet increased body weight, retroperitoneal fatness, glycaemia, and circulating estrogen levels. It aggravated the aging effects, leading to epithelial atrophy (∼32% reduction of epithelial height) and collagen fibers increase (83%). MLT alone did not alter biometric and physiological parameters, except for the prostate weight decrease, whereas it alleviated biometric as well as ameliorated acinar atrophy induced by high-lipid intake. Systemic oxidative stress increased, and prostatic glutathione peroxidase activity decreased fivefold with the high-fat diet despite the indole. Regardless of the diet, MLT triggered epithelial desquamation, reduced androgen receptor-positive cells, increased smooth muscle layer thickness (12%), decreased at least 50% corpora amylacea formation, and stimulated prostatic gluthatione-S-transferase activity. In conclusion, MLT partially recovered prostate damage induced by aging and the long-term high-fat diet and ameliorated degenerative prostate alterations.

Prostate immunology: A challenging puzzle

Mucosal immunity defines the relationship of surfaces in contact with the environment and integrates diverse tissues such as epidermis, gum, nose, gut, uterus and prostate with the immune system. Although considered part of a system, each mucosa presents specific immune features beyond the barrier and secretory functions. Information regarding the mucosal immunology of the male reproductive tract and the prostate gland in particular is scarce. In this review, we approach the prostate as an epithelial barrier and as part of the mucosal immune system. Finally, we also raise a series of questions that will improve the understanding of this gland, its role in reproduction and its sensitivity/resistance to disease.

Insulin exacerbated high glucose-induced epithelial-mesenchymal transition in prostatic epithelial cells BPH-1 and prostate cancer cells PC-3 via MEK/ERK signaling pathway

As two most common progressive diseases of aging, type 2 diabetes mellitus (T2DM) and benign prostatic hyperplasia (BPH) were all characterized by endocrine and metabolic disorders. Here, our clinical study showed that there were significant differences in fasting blood glucose (FBG), fasting insulin (FINS), insulin resistance index (HOMA-IR) and prostate volume (PV) between simple BPH patients and BPH complicated with T2DM patients. Further analysis showed that HOMA-IR was positively correlated with PV in BPH complicated with T2DM patients. The in vitro experiment results showed that high glucose (HG) promoted EMT process in a glucose-dependent manner in human prostate hyperplasia cells (BPH-1) and prostate cancer cells (PC-3), and this pathological process was exacerbated by co-culture with insulin. Mechanistically, insulin-induced exacerbation of EMT was depended on the activation of MEK/ERK signaling pathway, and we suggested that insulin and its analogs should be used very carefully for the clinical antihyperglycemic treatment of BPH complicated with T2DM patients.

Toll-like receptor 9 regulates metabolic profile and contributes to obesity-induced benign prostatic hyperplasia in mice

BACKGROUND

Benign prostatic hyperplasia (BPH) is associated with obesity and prostatic inflammation. The present study investigated the participation of toll-like receptor 9 (TLR9) in obesity-induced BPH, focusing on metabolic impairments, damage-associated molecular patterns (DAMP) levels and prostatic oxidative stress generation.

METHODS

C57BL/6 (WT) and TLR9 mutant male mice were fed with regular or high-fat diet for 12 weeks. Metabolic profile, functional protocols, reactive-oxygen species (ROS) generation, prostatic histological analysis and DAMP levels were analyzed. Western blotting for prostatic TLR9 signaling pathway was also performed.

RESULTS

BPH in WT obese animals was characterized by increased prostate weight, smooth muscle hypercontractility and prostatic epithelial hyperplasia. Higher epididymal fat weight and prostatic ROS generation along with increased fasting glucose, triglyceride and circulating DAMP levels were also observed in WT obese group. Conversely, TLR9 mutant obese animals exhibited lower epididymal fat weight, fasting glucose and triglyceride levels associated with reduced prostate hypercontractility, prostatic ROS and circulating DAMP levels. However, TLR9 mutant obese mice were not protected from obesity-associated prostatic overgrowth and epithelial hyperplasia. Interestingly, TLR9 mutant lean mice exhibited augmented fasting glucose and prostatic ROS levels compared with WT lean mice. Despite increased prostatic expression of TLR9 in WT obese mice, no differences were seen in MyD88 expression between groups.

CONCLUSION

Improved obesity-induced BPH-related prostatic smooth muscle hypercontractility in TLR9 obese mice may be associated with amelioration in the metabolic profile, ROS and DAMP generation. Therefore, TLR9 could be a valuable target to improve obesity-associated metabolic disorders and prostate smooth muscle hypercontractility in BPH.

Leptin promotes epithelial-mesenchymal transition in benign prostatic hyperplasia through downregulation of BAMBI

Benign prostatic hyperplasia (BPH) is a common disease in older men, and there is evidence that obesity is a causal factor. It is currently unclear whether the hormone leptin, which is positively correlated to obesity, is involved in BPH. The aim of this study was to determine the effect of leptin on testosterone-induced BPH in mice and to explore possible underlying mechanisms. Testosterone (3 mg/kg) was injected into wild-type and leptin-deficient ob/ob male mice for 14 consecutive days, and prostate tissues were subjected to various analyses. Additionally, BPH epithelial-1 (BPH-1) cells were treated with leptin to further investigate the underlying mechanisms. Leptin deficiency attenuated testosterone-induced morphological and pathological changes of BPH in mice. Furthermore, leptin deficiency alleviated the process of epithelial-mesenchymal transition (EMT) and suppressed the downregulation of bone morphogenic protein and activin membrane-bound inhibitor (BAMBI) in testosterone-treated mice. The in vitro data revealed that leptin significantly increased the expression of the EMT-associated marker vimentin but decreased the expression of E-cadherin, and that upregulation of BAMBI mitigated the intensity of leptin-induced EMT responses. Our results suggest that leptin can promote EMT in BPH through downregulating BAMBI. Suppressing leptin might be a potential therapeutic approach in preventing BPH development and progression.