Temporal gene signature of myofibroblast transformation in Peyronie's disease: first insights into the molecular mechanisms of irreversibility

BACKGROUND

Transformation of resident fibroblasts to profibrotic myofibroblasts in the tunica albuginea is a critical step in the pathophysiology of Peyronie's disease (PD). We have previously shown that myofibroblasts do not revert to the fibroblast phenotype and we suggested that there is a point of no return at 36 hours after induction of the transformation. However, the molecular mechanisms that drive this proposed irreversibility are not known.

AIM

Identify molecular pathways that drive the irreversibility of myofibroblast transformation by analyzing the expression of the genes involved in the process in a temporal fashion.

METHODS

Human primary fibroblasts obtained from tunica albuginea of patients with Peyronie's disease were transformed to myofibroblasts using transforming growth factor beta 1 (TGF-β1). The mRNA of the cells was collected at 0, 24, 36, 48, and 72 hours after stimulation with TGF-β1 and then analyzed using a Nanostring nCounter Fibrosis panel. The gene expression results were analyzed using Reactome pathway analysis database and ANNi, a deep learning-based inference algorithm based on a swarm approach.

OUTCOMES

The study outcome was the time course of changes in gene expression during transformation of PD-derived fibroblasts to myofibroblasts.

RESULTS

The temporal analysis of the gene expression revealed that the majority of the changes at the gene expression level happened within the first 24 hours and remained so throughout the 72-hour period. At 36 hours, significant changes were observed in genes involved in MAPK-Hedgehog signaling pathways.

CLINICAL TRANSLATION

This study highlights the importance of early intervention in clinical management of PD and the future potential of new drugs targeting the point of no return.

STRENGTHS AND LIMITATIONS

The use of human primary cells and confirmation of results with further RNA analysis are the strengths of this study. The study was limited to 760 genes rather than the whole transcriptome.

CONCLUSION

This study is to our knowledge the first analysis of temporal gene expression associated with the regulation of the transformation of resident fibroblasts to profibrotic myofibroblasts in PD. Further research is warranted to investigate the role of the MAPK-Hedgehog signaling pathways in reversibility of PD.

Hydroxypyridone anti-fungals selectively induce myofibroblast apoptosis in an in vitro model of hypertrophic scars

Hypertrophic scars are a common complication of burn injuries, yet there are no medications to prevent their formation. During scar formation, resident fibroblasts are transformed to myofibroblasts which become resistant to apoptosis. Previously, we have shown that hydroxypyridone anti-fungals can inhibit transformation of fibroblasts, isolated from hypertrophic scars, to myofibroblasts. This study aimed to investigate if these drugs can also target myofibroblast persistence. Primary human dermal fibroblasts, derived from burn scar tissue, were exposed to transforming growth factor beta-1 (TGF-β1) for 72 h to induce myofibroblast transformation. The cells were then incubated with three hydroxypyridone anti-fungals (ciclopirox, ciclopirox ethanolamine and piroctone olamine; 0.03-300 μM) for a further 72 h. The In-Cell ELISA method was utilised to quantify myofibroblast transformation by measuring alpha-smooth muscle actin (α-SMA) expression and DRAQ5 staining, to measure cell viability. TUNEL staining was utilised to assess if the drugs could induce apoptosis. When given to established myofibroblasts, the three hydroxypyridones did not reverse myofibroblast transformation, but instead elicited a concentration-dependent decrease in cell viability. TUNEL staining confirmed that the hydroxypyridone anti-fungals induced apoptosis in established myofibroblasts. This is the first study to show that hydroxypyridone anti-fungals are capable of inducing apoptosis in established myofibroblasts. Together with our previous results, we suggest that hydroxypyridone anti-fungals can prevent scar formation by preventing the formation of new myofibroblasts and by reducing the number of existing myofibroblasts.

European Society of Sexual Medicine consensus statement on the use of animal models for studying Peyronie's disease

Introduction

Animal models are frequently used for translational research in Peyronie's disease (PD). However, due to lack of availability of guidelines, there is some heterogeneity in study design, data reporting, and outcome measures.

Aim

This European Society for Sexual Medicine consensus statement aims to provide guidance in utilization of animal models in PD research in a standardized and uniform fashion.

Methods

PubMed was searched for studies using animal models for PD. The following search terms were used: ("Peyronie's disease" OR "penile fibrosis" OR "penile curvature" OR "induration penis plastica" OR "erectile dysfunction") AND ("rodent" OR "mouse" OR "mice" OR "rat" OR "rabbit").

Outcomes

This European Society for Sexual Medicine statement describes best practice guidelines for utilization of animals in PD research: power calculation, details of available models, surgical procedures, and measurement techniques, while highlighting possible pitfalls and translational limitations of the models.

Results

In total, 2490 studies were retrieved and 2446 articles were excluded. A total of 44 studies were included, of which 40 studies used rats, 1 study used both rats and mice, 1 study used a genetic mouse model, and 2 studies used rabbits. A significant number of the studies (70.5%) used transforming growth factor β 1 for induction of fibrosis. Oxford 2011 Levels of Evidence criteria could not be applied due to the nature of the studies.

Conclusion

Despite certain limitations of PD animal models presented, we aimed to provide guidance for their appropriate use in translational research, with the purpose of improving study quality and reproducibility as well as facilitating interpretation of reported results and conclusions.

Statins synergize with phosphodiesterase type 5 inhibitors but not with selective estrogen receptor modulators to prevent myofibroblast transformation in an in vitro model of Peyronie's disease

BACKGROUND

Peyronie's disease (PD) is a fibrotic disorder characterized by plaque formation in the tunica albuginea (TA) of the penis, and we have previously shown that inhibition of transformation of TA-derived fibroblasts to myofibroblasts using a combination phosphodiesterase type 5 (PDE5) inhibitors and selective estrogen receptor modulators (SERMs) is effective in slowing the progression of early PD.

AIM

The study sought to investigate whether combinations of statins with PDE5 inhibitors or SERMs would affect myofibroblast transformation in vitro.

METHODS

Primary fibroblasts were isolated from TA of patients with PD and stimulated with transforming growth factor β1 in the absence and presence of a range of concentrations of statins, PDE5 inhibitors, SERMs, and their combinations for 72 hours before quantifying α-smooth muscle actin using in-cell enzyme-linked immunosorbent assay.

OUTCOMES

The prevention of transforming growth factor β1-induced transformation of TA-derived fibroblasts to myofibroblasts was measured in vitro.

RESULTS

Statins (simvastatin, lovastatin) inhibited myofibroblast transformation in a concentration-dependent manner with half maximal inhibitory concentration values of 0.77 ± 0.07 μM and 0.8 ± 0.13 μM, respectively. Simvastatin inhibited myofibroblast transformation in a synergistic fashion when combined with vardenafil (a PDE5 inhibitor; log alpha >0). Combination of tamoxifen (a SERM) and simvastatin did not show synergy (log alpha <0). When 3 drugs (simvastatin, vardenafil, and tamoxifen) were combined, the effect was not synergistic, but rather was additive.

CLINICAL IMPLICATIONS

A combination of a statin with a PDE5 inhibitor might be useful in the clinic to slow the progression of the disease in patients with early PD; however, caution should be taken with such a combination because of the reported myopathy as a side effect.

STRENGTHS AND LIMITATIONS

The use of primary human cells from patients with PD is a strength of this study. The mechanisms by which these drug classes exert synergy when used in combination was not investigated.

CONCLUSION

This is the first demonstration of an antifibrotic synergy between statins and PDE5 inhibitors.

Phenotypic screening of 1,953 FDA-approved drugs reveals 26 hits with potential for repurposing for Peyronie's disease

Drug repurposing has been shown to bring safe medications to new patient populations, as recently evidenced by the COVID-19 pandemic. We investigated whether we could use phenotypic screening to repurpose drugs for the treatment of Peyronie's disease (PD). PD is a fibrotic disease characterised by continued myofibroblast presence and activity leading to formation of a plaque in the penile tunica albuginea (TA) that can cause pain during erection, erectile dysfunction, and penile deformity. PD affects 3-9% of men with treatment options limited to surgery or injection of collagenase which can only be utilised at late stages after the plaque is formed. Currently there are no approved medications that can be offered to patients presenting with early disease before the formation of the plaque. Drug repurposing may therefore be the ideal strategy to identify medical treatments to address this unmet medical need in early PD. We used primary human fibroblasts from PD patients in a phenotypic screening assay that measures TGF-β1-induced myofibroblast transformation which is the main cellular phenotype that drives the pathology in early PD. A library of FDA-approved 1,953 drugs was screened in duplicate wells at a single concentration (10 μM) in presence of TGF-β1. The myofibroblast marker α-SMA was quantified after 72h incubation. A positive control of SB-505124 (TGF-β1 receptor antagonist) was included on each plate. Hits were defined as showing >80% inhibition, whilst retaining >80% cell viability. 26 hits (1.3%) were identified which were divided into the following main groups: anti-cancer drugs, anti-inflammation, neurology, endocrinology, and imaging agents. Five of the top-ten drugs that increase myofibroblast-transformation appear to act on VEGFR. This is the first phenotypic screening of FDA-approved drugs for PD and our results suggest that it is a viable method to predict drugs with potential for repurposing to treat early PD.

Associations Between Mobile Health Technology use and Self-rated Quality of Life: A Cross-sectional Study on Older Adults with Cognitive Impairment

Background: Quality of life (QoL) is affected even at early stages in older adults with cognitive impairment. The use of mobile health (mHealth) technology can offer support in daily life and improve the physical and mental health of older adults. However, a clarification of how mHealth technology can be used to support the QoL of older adults with cognitive impairment is needed. Objective: To investigate factors affecting mHealth technology use in relation to self-rated QoL among older adults with cognitive impairment. Methods: A cross-sectional research design was used to analyse mHealth technology use and QoL in 1,082 older participants. Baseline data were used from a multi-centered randomized controlled trial including QoL, measured by the Quality of Life in Alzheimer’s Disease (QoL-AD) Scale, as the outcome variable. Data were analyzed using logistic regression models. Results: Having moderately or high technical skills in using mHealth technology and using the internet via mHealth technology on a daily or weekly basis was associated with good to excellent QoL in older adults with cognitive impairment. Conclusions: The variation in technical skills and internet use among the participants can be interpreted as an obstacle for mHealth technology to support QoL.

Single-cell Transcriptomics Uncover a Novel Role of Myeloid Cells and T-lymphocytes in the Fibrotic Microenvironment in Peyronie's Disease

BACKGROUND

Peyronie's disease (PD) is an acquired fibrotic disease affecting the penile tunica albuginea that can lead to curvature and deformities, shortening, and erectile dysfunction. Although immunological mechanisms have been suggested for the pathophysiology of PD, these have not been investigated using single-cell transcriptomics.

OBJECTIVE

To investigate the immunological signature of plaques from PD patients using immunohistochemistry (IHC) and single-cell RNA sequencing (scRNA-Seq).

DESIGN, SETTING, AND PARTICIPANTS

Tunica albuginea biopsy was performed in patients undergoing penile surgery for either PD (n = 12) or plication or penile cancer (control, n = 6). The inclusion criteria for PD patients were stable chronic disease (≥12 mo in duration) and no previous penile surgery or intralesional injection therapy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

IHC was performed on surgical samples from ten patients with PD and five control subjects. An additional two PD and one control sample were used for scRNA-Seq (droplet-based; 10X Genomics). Cell clusters were visualised using heatmaps and t-distributed stochastic neighbour embedding plots (BioTuring v2.7.5).

RESULTS AND LIMITATIONS

IHC revealed the presence of myeloid dendritic cells (DCs; CD68⁺, TLR4⁺, CD206⁺), cytotoxic T lymphocytes (CTLs; CD3⁺, CD8⁺), and B lymphocytes (CD20⁺) in PD plaques, which were absent in controls. scRNA-Seq yielded results for 3312 PD and 5658 control cells. Cell clusters contained fibroblasts (COL1A2⁺), myofibroblasts (COL1A2⁺, ACTA2⁺), smooth muscle cells (ACTA2⁺, DES⁺), endothelial cells (VWF⁺), myeloid cells (CD14⁺), T lymphocytes (CD3D⁺), and neutrophils (ALPL⁺). Myeloid cell subclustering showed infiltration of monocyte-derived cells; control tissue contained classical DCs and resident macrophages. Lymphocyte subclustering revealed mucosal-associated invariant T (MAIT) cells and CTLs in PD. Differential gene expression suggests an increase in inflammatory and immune responses in chronic PD. The study is limited by the small scRNA-seq sample size (n = 3) for IHC, mitigated by a larger cohort of historic paraffin-embedded samples (n = 15), which showed largely parallel findings. Owing to tissue stiffness and extracellular matrix adhesion, our single-cell yield was lower for PD than for the control sample.

CONCLUSIONS

Our data suggest that even in the chronic PD stage (painless and stable curvature) there is a sustained inflammatory reaction. While vascularisation and collagen production are elevated, the inflammation is driven by specialised monocyte-derived CTL and MAIT cells. These findings could uncover new avenues for medical treatment of PD.

PATIENT SUMMARY

We looked at the role of the immune system in patients suffering from Peyronie's disease, a condition causing shortening and curvature of the penis. We found that even in a stable, chronic stage of the disease, there is activation of the immune system. Our results suggest that there is potential for novel treatments for this condition.

Comparison of PEAK PlasmaBlade™ to conventional diathermy in abdominal-based free-flap breast reconstruction surgery-A single-centre double-blinded randomised controlled trial

BACKGROUND

Electrosurgery makes dissection with simultaneous haemostasis possible. The produced heat can cause injury to the surrounding tissue. The PEAK PlasmaBlade™(PPB) is a new electrosurgery device which may overcome this by having the ability to operate on a lower temperature, therefore reducing collateral thermal damage.

METHOD

A single-centre, double-blinded, randomised controlled trial (RCT) was conducted which included 108 abdominal-based free-flap breast reconstruction patients who had their flap raise performed using either the PPB (n = 56) or the conventional diathermy (n = 52). Data were collected during their in-patient stay and out-patient appointments. The primary outcome value was the number of days the abdominal drains were required.

RESULTS

Baseline characteristics were similar between the groups, except a significantly lower flap weight in the PPB group. The median number of days the drains were required did not differ significantly (p = 0.48; 6.0 days for the diathermy and 5.0 days for the PPB). The total drain output (p = 0.68), the inflammatory cytokine in the drain fluid (p>0.054) and complications (p>0.24) did not differ significantly between the two groups. At the 2-week follow-up appointment, there was a trend towards less abdominal seromas on abdominal ultrasound (p = 0.09) in the PPB group which were significantly smaller (p = 0.04).

CONCLUSION

The use of the PPB did not result in a significant reduction of drain requirement, total drain output or inflammatory cytokines but did reduce the size of seroma collections at the 2-week follow-up appointment. Therefore, the use of the PPB device could reduce early seroma formation after drain removal.

Phosphodiesterase Type 5 Inhibitors and Selective Estrogen Receptor Modulators Can Prevent But Not Reverse Myofibroblast Transformation in Peyronie's Disease

BACKGROUND

Myofibroblast transformation is a key step in the pathogenesis of Peyronie's disease (PD). Phosphodiesterase type 5 inhibitors (PDE5is) and selective estrogen receptor modulators (SERMs) can prevent the formation of fibrosis in in vitro and in vivo models of PD. However, it is unknown whether these drugs can also reverse established fibrosis.

AIM

To investigate whether PDE5is and SERMs can reverse transforming growth factor beta 1 (TGF-β1)-induced myofibroblast transformation and determine the point of no return.

METHODS

In-Cell enzyme-linked immunosorbent assay was used to quantify TGF-β1-induced myofibroblast transformation of human primary fibroblasts isolated from tunica albuginea (TA) of patients undergoing surgery for treatment of PD. Extracellular matrix production and collagen contraction assays were used as secondary assays. Reverse transcription-quantitative polymerase chain reaction and In-Cell enzyme-linked immunosorbent assay were used to measure drug target expression. PDE5i (vardenafil) and SERM (tamoxifen) were applied at various time points after TGF-β1.

OUTCOMES

Reversibility of myofibroblast transformation and drug target expression were investigated in a time-dependent manner in TA-derived fibroblasts.

RESULTS

Vardenafil or tamoxifen could not reverse the myofibroblast traits of alpha-smooth muscle actin expression and extracellular matrix production, whereas only tamoxifen affected collagen contraction after 72 hours of TGF-β1 treatment. Phosphodiesterase 5A and estrogen receptor (ER)-β were downregulated after 72 hours, and estrogen receptor -α protein could not be quantified. Tamoxifen could prevent myofibroblast transformation until 36 hours after TGF-β1 treatment, whereas vardenafil could prevent only 24 hours after TGF-β1 treatment. This was mirrored by downregulation of drug targets on mRNA and protein level. Furthermore, antifibrotic signaling pathways, peroxisome proliferator-activated receptor gamma and betaglycan (TGFB receptor III), were significantly downregulated after 36 hours of TGF-β1 exposure, as opposed to upregulation of profibrotic thrombospondin-1 at the same time point.

CLINICAL TRANSLATION

This study suggests that using PDE5is and SERMs might only help for early-phase PD and further highlights the need to test drugs at the appropriate stage of the disease based on their mechanism of action.

STRENGTHS & LIMITATIONS

The study uses primary human TA-derived fibroblasts that enhances translatability of the results. Limitations include that only 1 example of PDE5i- and SERM-type drug was tested. Time course experiments were only performed for marker expression experiments and not for functional assays.

CONCLUSION

This is the first study to demonstrate that timing for administration of drugs affecting myofibroblast transformation appears to be vital in in vitro models of PD, where 36 hours of TGF-β1 treatment can be suggested as a "point of no return" for myofibroblast transformation. Ilg MM, Stafford SJ, Mateus M, et al. Phosphodiesterase Type 5 Inhibitors and Selective Estrogen Receptor Modulators Can Prevent But Not Reverse Myofibroblast Transformation in Peyronie's Disease. J Sex Med 2020;17:1848-1864.

What role do pharmaceuticals play in the treatment of Peyronie's disease and is there a need for new emerging drugs?

INTRODUCTION

Finding novel medical treatment for Peyronie's disease (PD) has suffered from similar limitations and difficulties as other fibrotic diseases.Areas covered: Underlying fibrosis, there is a vastly complex intertwining of several pathways. Focusing on a single target during antifibrotic drug development has not led to the development of many efficacious drugs, especially in PD. Inhibiting one cog in this large machinery usually leads to activation of compensatory mechanisms.Expert opinion: Novel strategies in drug discovery such as phenotypical drug screening and gene expression profiling technologies could provide a solution for this impasse.

KRAS mutation status to predict response in first-line capox and bevacizumab therapy for metastatic colorectal cancer

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Background: Capecitabine and Oxaliplatin (CAPOX) combined with the humanised anti-vascular endothelial growth factor Bevacizumab represents a standard first-line treatment for metastatic colorectal cancer (mCRC). However, the response rate is only approximately 50% and currently there is no biomarker to predict treatment response. This study aims to correlate KRAS status with response to CAPOX and Bevacizumab (CAPOX-Bev). Methods: Forty-five patients with mCRC were retrospectively screened between January 2012 and December 2015 at Broomfield Hospital, UK. DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue samples (Qiagen FFPE tissue kit). Twelve types of mutations in Exons 2, 3 and 4 of the KRAS gene were analysed using a real-time quantitative polymerase chain reaction (qPCR) assay (EntroGen). Treatment response was assessed according to RECIST criteria version 1.1 by comparing pre-treatment and post-treatment radiological CT scans. The KRAS status was correlated with CT tumour response (responders: partial response and complete response; non-responders: progressive disease and stable disease). A Chi-square test was used to determine the correlation between KRAS status and tumour response. Results: 19/45 patients were KRAS wild type (WT, 42%) and 26 were KRAS mutant (MT, 58%). 8/19 (42%) KRAS WT patients were responders, compared to 3/26 (12%) KRAS MT patients. Conversely 11/19 (58%) of WT patients were non-responders, compared to 23/26 (88%) MT patients. The correlation of treatment response and KRAS status was statistically significant (p = 0.018), with a 31% difference in response rate between KRAS WT (42%) and KRAS MT (12%) groups. Conclusions: Within this pilot retrospective analysis, KRAS mutations demonstrated clinical value in identifying patients who are more likely to respond to first-line CAPOX-Bev in advanced colorectal cancer. This finding requires prospective evaluation within a large patient cohort powered to further detect potential differences in overall and progression free survival. [Table: see text]

The beta3-adrenoceptor agonist GW427353 (Solabegron) decreases excitability of human enteric neurons via release of somatostatin

BACKGROUND & AIMS

beta3 Adrenoceptor (beta3-AR) is expressed on adipocytes and enteric neurons. GW427353 is a human selective beta3-AR agonist with visceral analgesic effects. Some of its effects may involve release of somatostatin (SST) and actions on enteric neurons. The aim of this study was to investigate the mode of action of GW427353 in human submucous neurons.

METHODS

Voltage sensitive dye imaging was used to record from human submucous neurons. SST release from human primary adipocytes was measured with enzyme-linked immunoabsorbent assay. Immunohistochemistry was used to detect adiponectin, beta3-AR, SST, SST2 receptors, tyrosine hydroxylase (TH), and protein gene product 9.5.

RESULTS

Confocal imaging showed cytoplasmic beta3-AR labeling in somata of submucous neurons and nerve varicosities. GW427353 had no direct postsynaptic actions but decreased fast synaptic input to submucous neurons. Tissue perfusion with GW427353 reduced nicotine-evoked neuronal spike frequency, an effect prevented by the beta3-AR antagonist SR-59230 and the SST2-receptor antagonist CYN154806 and mimicked by the SST2 receptor agonist octreotide. Adipocytes expressed adiponectin, beta3-AR, and SST. TH-positive fibers were in close proximity to adipocytes. Submucous neurons expressed SST2 receptors. Human primary adipocytes released SST in response to GW427353 in a concentration-dependent manner, an effect abolished by SR-59230.

CONCLUSIONS

Inhibitory action of GW427353 involves release of SST which stimulates inhibitory SST2 receptors on human submucous neurons. Adipocytes are a potential source for SST. beta3-AR activation may be a promising approach to reduce enteric neuron hyperexcitability. The action of GW427353 may be the neurophysiologic correlate of its beneficial effect in patients with irritable bowel syndrome.

5-hydroxyindalpine, an agonist at the putative 5-HT receptor, has no activity on human recombinant monoamine receptors but accelerates distension-induced peristalsis in mouse isolated colon

Although the putative 5-HT(1P) receptor has been implicated to have a role in peristalsis, experiments which suggest this function are preliminary or have measured only components of the reflex. We have, therefore, further characterized a reported agonist at this receptor (5-hydroxyindalpine; 5-OHIP) and investigated the effects of 5-OHIP and 5-hydroxytrytophan-dipeptide (5-HTP-DP), a reported 5-HT(1P) receptor antagonist, on distension-induced peristalsis in mouse colon. The effects of 5-OHIP on intracellular calcium, cyclic adenosine monophosphate concentrations or GTPgammaS binding were measured in cell lines expressing human recombinant 5-HT(1A, 1B, 1D, 2A, 2B, 2C, 3, 4, 6, 7) and alpha(1A), alpha(1B), D(1), D(2), D(3), H(1), H(3) receptors. The effects of 5-OHIP and 5-HTP-DP on peristalsis were assessed by measuring changes in frequency and times to reach threshold of peristaltic contractions, as well as the threshold and maximum pressures of each peristaltic stroke. 5-hydroxyindalpine (1 nmol L(-1)-10 micromol L(-1)) had no significant activity at any of the receptors studied. However, 5-OHIP (0.1 nmol L(-1)-1 micromol L(-1)) concentration-dependently increased the frequency of peristalsis (EC(50) = 4.4 nmol L(-1)) and reduced the time taken to reach threshold and threshold pressure, without altering maximum pressures. The maximum effect of 5-OHIP was at 1 micromol L(-1) (68.0 +/- 14.5% increase in frequency); 10 micromol L(-1) decreased peristalsis. 5-hydroxytrytophan-dipeptide (1-300 nmol L(-1)) also increased the frequency of peristalsis and prevented the actions of 5-OHIP. The higher concentration (1 micromol L(-1)) transiently inhibited peristalsis and after recovery, prevented the actions of 5-OHIP but not the excitatory activity of the cholinesterase inhibitor neostigmine. In summary, the present data demonstrate an interaction of '5-HT(1P)-ligands' with the peristaltic reflex. However, the absence of an effect of 5-OHIP on a range of different monoamine receptors continues to highlight the need to investigate the identity of the putative 5-HT(1P) receptor.

GSK962040: a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility

There is an urgent clinical need for a safe, efficacious stimulant of gastric emptying; current therapies include erythromycin (an antibiotic with additional properties which preclude chronic use) and metoclopramide (a 5-hydroxytryptamine type 4 receptor agonist and an antagonist at brain D2 receptors, associated with movement disorders). To move away from the complex motilide structure of erythromycin, a small molecule motilin receptor agonist, GSK962040, was identified and characterized. The compound was evaluated using recombinant human receptors, rabbit and human isolated stomach preparations known to respond to motilin and in vivo, by measuring its ability to increase defecation in conscious rabbits. At the human motilin receptor, the pEC50 (the negative logarithm to base 10 of the EC50 value, the concentration of agonist that produces 50% of the maximal response) values for GSK962040 and erythromycin as agonists were, respectively, 7.9 and 7.3; GSK962040 had no significant activity at a range of other receptors (including ghrelin), ion channels and enzymes. In rabbit gastric antrum, GSK962040 300 nmol L(-1)-10 micromol L(-1) caused a prolonged facilitation of the amplitude of cholinergically mediated contractions, to a maximum of 248 +/- 47% at 3 micromol L(-1). In human-isolated stomach, GSK962040 10 micromol L(-1), erythromycin 10 micromol L(-1) and [Nle13]-motilin 100 nmol L(-1), each caused muscle contraction of similar amplitude. In conscious rabbits, intravenous doses of 5 mg kg(-1) GSK962040 or 10 mg kg(-1) erythromycin significantly increased faecal output over a 2-h period. Together, these data show that GSK962040, a non-motilide structure, selectively activates the motilin receptor. Simplification of the structural requirements to activate this receptor greatly facilitates the design of potentially new medicines for gastroparesis.

Synergy between 5-HT4 receptor activation and acetylcholinesterase inhibition in human colon and rat forestomach

5-Hydroxytryptamine (5-HT4) receptor agonists increase gastrointestinal (GI) motility by enhancing enteric acetylcholine release which is then metabolized by acetylcholinesterase (AChE) to inactive metabolites. As both AChE inhibitors and, more usually, 5-HT4 receptor agonists are used to increase GI motility, an understanding of how these two different types of drugs might interact becomes of great importance. Our aim was to investigate the hypothesis that the effect of AChE inhibition will synergise with the ability of 5-HT4 receptor agonism to increase cholinergic activity, leading to an effect greater than that evoked by each action alone. We tested the activity of the 5-HT4 receptor agonist, prucalopride (10 nmol L(-1)-30 micromol L(-1)) and an AChE inhibitor, neostigmine (1 nmol L(-1)-10 micromol L(-1)) on cholinergically mediated contractions elicited by electrical field stimulation of human isolated colon circular muscle and rat isolated forestomach longitudinal strips. The experiments with human colon were performed in the presence of an inhibitor of nitric oxide synthase (N(omega)-nitro-l-arginine methyl ester, 300 micromol L(-1)). Prucalopride and neostigmine both enhanced cholinergic contractions in both tissues. The effect of prucalopride was inhibited in both tissues by SB-204070, a 5-HT4 receptor antagonist. In the presence of a minimum effective concentration of neostigmine (30 nmol L(-1)) and a submaximum concentration of prucalopride (3 micromol L(-1)) the enhancement of contractions was greater than either compound alone in both tissues. These data demonstrate that the combination of prucalopride and neostigmine potentiate cholinergic contractions more than their arithmetic sum of their individual values. The results suggest that a synergy between 5-HT4 receptor agonism and AChE inhibition could be established pharmacologically which could be utilized as a novel prokinetic approach to functional GI disorders.

5-HT4 receptor agonists enhance both cholinergic and nitrergic activities in human isolated colon circular muscle

Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively.

Physiology of erectile function

INTRODUCTION

There are numerous investigations concerning the balance and interactions between relaxant and contractile factors regulating penile smooth muscle (arterial and trabecular) tone, the determinant of penile flaccidity or erection. Enhanced knowledge of erectile physiology may improve management of men with erectile dysfunction. Aim. To provide state-of-the-art knowledge on the physiology of erectile function.

METHODS

An international consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a process over a two-year period. Concerning the physiology of erectile function and pathophysiology of erectile dysfunction committee, there were seven experts from five countries.

MAIN OUTCOME MEASURE

Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

RESULTS

Key roles in the mechanism determining the tone of penile smooth muscle are played by the rise of the intracellular concentration of free calcium and the sensitivity of the contractile machinery to calcium, endothelial health, endothelium-derived nitric oxide, endothelium-derived hyperpolarizing factor (EDHF), neuronal nitric oxide, cyclic guanosine monophosphate-dependent protein kinase and phosphodiesterase type 5.

CONCLUSIONS

A number of new mechanisms have been identified for the local regulation of penile smooth muscle contractility and therefore penile erection. Molecules participating in these pathways can be considered targets for the development of new treatments to treat erectile dysfunction.

The Breakdown of Preformed Advanced Glycation End Products Reverses Erectile Dysfunction in Streptozotocin‐Induced Diabetic Rats: Preventive Versus Curative Treatment

OBJECTIVES

Accumulation of advanced glycation end products (AGEs) has been linked to many of the complications of diabetes mellitus, including erectile dysfunction (ED). Furthermore, it has been demonstrated that inhibitors of AGE formation, such as aminoguanidine, can prevent ED in diabetic animals. However, it is unknown whether late administration of a putative cross-link breaker, ALT-711, can reverse diabetic ED. We therefore compared ALT-711 and aminoguanidine in their ability to reverse ED in diabetic rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats were randomly divided into four groups: (i) age-matched controls; (ii) streptozotocin (STZ)-induced diabetic rats (60 mg/kg; intraperitoneal injection); (iii) STZ diabetic rats treated with ALT-711 (3 mg/kg/day, intraperitoneal injection); and (iv) STZ diabetic rats treated with aminoguanidine (1 gm/L in drinking water) during the final 6 weeks of 12 weeks of induced diabetes. At the end of 12 weeks, erectile response to cavernous nerve stimulation (CNS) was determined. Neuronal nitric oxide synthase (nNOS) contents were measured in all penises, and AGE levels were determined both in penile tissues and in serum samples.

RESULTS

Erectile responses to CNS and penile nNOS protein content were significantly reduced, while AGE levels were elevated in the penises and serum of untreated diabetic animals. Treatment with ALT-711, but not with aminoguanidine, reversed ED and nNOS depletion and reduced serum and penile tissue AGE levels.

CONCLUSIONS

These results suggest that cross-link breakers, such as ALT-711, are the optimal therapeutic approach, compared with treatment with inhibitors of AGE formation, in the reversal of diabetes-related ED.

Investigation of cavernosal smooth muscle dysfunction in low flow priapism using an in vitro model

The effects of hypoxia (pO2: 50 mmHg), acidosis (pH: 6.9) or glucopenia (absence of glucose) in vitro on the tone of the rabbit corpus cavernosum were investigated. The recovery of smooth muscle contractility following exposure to these conditions was also assessed. Hypoxia, acidosis or glucopenia alone or in combination showed a sustained reduction in the tone. Reperfusion of tissue strips showed complete recovery of smooth muscle tone for all conditions except when hypoxia and glucopenia were combined or when hypoxia, glucopenia and acidosis were used in combination. Incomplete recovery of tone was associated with a significant reduction in tissue ATP concentrations and an increase in the number of TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling)-positive nuclei. This indicates that following reversal of hypoxia, acidosis and glucopenia, failure of conventional alpha-adrenergic agonists to produce tumescence in low flow priapism is associated with irreversible smooth muscle cell dysfunction, which is linked to ATP reduction and smooth muscle cell death.

Pathophysiology of Erectile Dysfunction

INTRODUCTION

Multiple regulatory systems are involved in normal erectile function. Disruption of psychological, neurological, hormonal, vascular, and cavernosal factors, individually, or in combination, can induced erectile dysfunction (ED). The contribution of neurogenic, vascular, and cavernosal factors was thoroughly reviewed by our committee, while psychological and hormonal factors contributing to ED were evaluated by other committees.

AIM

To provide state of the art knowledge on the physiology of ED.

METHODS

An international consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five different continents developed in a process over a 2-year period. Concerning the pathophysiology of ED committee, there were seven experts from five different countries.

MAIN OUTCOME MEASURE

Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

RESULTS

The epidemiology and classification of neurogenic ED was reviewed. The evidence for the association between vascular ED and atherosclerosis/hypercholesterolemia, hypertension and diabetes was evaluated. In addition, the pathophysiological mechanisms implicated in vascular ED were defined, including: arterial remodeling, increased vasoconstriction, impaired neurogenic vasodilatation, and impaired endothelium-dependent vasodilatation. The possible mechanisms underlying the association between chronic renal failure and ED were also evaluated as well as the evidence supporting the association of ED with various classes of medications.

CONCLUSIONS

A better understanding of how diseases interfere with the physiological mechanisms that regulate penile erection has been achieved over the last few years, which helps establish a strategy for the prevention and treatment of ED.

Nitrergic neurodegeneration in cerebral arteries of streptozotocin-induced diabetic rats: a new insight into diabetic stroke

Although autonomic neuropathy is recognized as an independent risk factor for stroke in diabetes, the mechanism by which autonomic nerves are involved in this pathology is unknown. Parasympathetic (cholinergic) nerves of the autonomic nervous system are known to innervate and to cause relaxation of cerebral arteries by releasing nitric oxide (NO); hence, they are called nitrergic nerves. However, the effect of diabetes on nitrergic nerves is unknown. Here, we show that perivascular nitrergic nerves around the cerebral arteries degenerate in two phases in streptozotocin-induced diabetic rats. In the first phase, perivascular nitrergic nerve fibers remain intact while they lose their neuronal NO synthase content. This phase is reversible with insulin treatment. In the second phase, nitrergic cell bodies in the ganglia are lost via apoptosis in an irreversible manner. Throughout the two phases, irreversible thickening of the smooth muscle layer of cerebral arteries is observed. This is the first demonstration of nitrergic degeneration in diabetic cerebral arteries, which could elucidate the link between diabetic autonomic neuropathy and stroke.

ORIGINAL RESEARCH—BASIC SCIENCE: A Nitric Oxide‐Releasing PDE5 Inhibitor Relaxes Human Corpus Cavernosum in the Absence of Endogenous Nitric Oxide

INTRODUCTION

In conditions with severe deficiency of endogenous nitric oxide (NO), such as long-term diabetes and cavernosal nerve injury, phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in the treatment of erectile dysfunction. NO-releasing PDE5 inhibitors could be an alternative therapeutic approach in such cases.

AIM

We therefore aimed to compare sildenafil and NO-releasing sildenafil (NCX-911) in relaxing human corpus cavernosum in the absence or presence of endogenous NO.

METHODS

The two compounds were compared in reducing the phenylephrine-induced tone of human corpus cavernosum in the presence or absence of an inhibitor of NO synthase (L-NAME; 500 microM) or an inhibitor of soluble guanylate cyclase (ODQ, 10 microM).

RESULTS

NCX-911 was as potent as sildenafil in control conditions (EC(50) = 733.1 +/- 94.4 nM and 800.7 +/- 155.8 nM, respectively). The potency of NCX-911 was not altered but that of sildenafil decreased significantly in the presence of L-NAME (EC(50) = 980.4 +/- 106.7 nM and 2446.7 +/- 256.8 nM, respectively; P < 0.001 for sildenafil vs. control). Both compounds below 1 microM failed to induce relaxation in the presence of ODQ (EC(50) = 6,578 +/- 1150 nM and 6,488 +/- 938 nM for NCX-911 and sildenafil, respectively).

CONCLUSION

These results show that the potency of NCX-911 was maintained unlike sildenafil in the absence of endogenous NO confirming the potential use of NO-releasing PDE5 inhibitors in NO-deficient conditions.

Point of NO return for nitrergic nerves in diabetes: a new insight into diabetic complications

Aberrations in nitrergic neurotransmission, due to a decrease in neuronal nitric oxide (NO) synthase (nNOS) protein, play an important role in the pathogenesis of autonomic neuropathy in diabetes. Until recently the mechanism of the decrease in nNOS protein content in nitrergic nerves during diabetes was debated. Two different views were prevailing, one attributing the nNOS decrease to nitrergic nerve degeneration, the other to an alteration in nNOS expression. Our recent study in which we showed that nitrergic nerves undergo a degenerative process in two phases might bring a solution to this debate. Our model suggests that, in the early stages of diabetes, nNOS expression is decreased in the nitrergic axons while nNOS levels are unaffected in the cell bodies, most probably due to a defect in axonal transport. This decrease is reversible with insulin treatment. As the diabetes progresses, nNOS starts to accumulate in the cell bodies since it cannot be transported down to the axons. Increased nNOS protein and NO production coincide with accumulation of advanced glycation endproducts (AGEs) in the blood and tissues. Synergistic action of AGEs and endogenous NO leads to increased oxidative stress within the cell bodies, resulting in apoptosis. This degenerative phase of nitrergic neuropathy is not reversible with insulin treatment. This suggests a point of no return for autonomic nerves after which the degenerative changes become irreversible. Future therapeutic approaches could target the defective axonal transport and prevention of AGEs accumulation before this point of no return. In the later stages, reduction of AGEs, replenishment of lost nitrergic neurons and restoration of function are putative therapeutic targets.

A comparative study of sildenafil, NCX-911 and BAY41-2272 on the anococcygeus muscle of diabetic rats

We compared the effects of a nitric oxide (NO)-releasing sildenafil (NCX-911), NO-independent soluble guanylate cyclase activator (BAY41-2272) and sildenafil on the anococcygeus muscle from streptozotocin-induced 16-weeks diabetic rats. NCX-911, BAY41-2272 and sildenafil reduced the phenylephrine-induced tone in the control group (EC50=1088.8+/-165.0, 151.6+/-9.3 and 827.1+/-167.3 nM, respectively). The potencies of NCX-911 and BAY41-2272 were not altered, but that of sildenafil was significantly reduced in the diabetic group. EC50 values for NCX-911, BAY41-2272 and sildenafil in the diabetic group were 1765.9+/-303.5, 209.7+/-27.3 and 2842.2+/-640.3 nM, respectively (P<0.05 for sildenafil). Nitrergic relaxation responses were significantly decreased in the diabetic group. The remaining nitrergic relaxation responses were potentiated by BAY41-2272 but not by sildenafil or NCX-911. These results confirm that endogenous NO derived from nitrergic nerves is significantly decreased in diabetes, and suggest that NO-releasing PDE5 inhibitors and NO-independent soluble guanylate cyclase activators could be more useful than PDE5 inhibitors in the treatment of ED in long-term diabetes.

NCX-911, a novel nitric oxide-releasing PDE5 inhibitor relaxes rabbit corpus cavernosum in the absence of endogenous nitric oxide

Phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in treating erectile dysfunction (ED) in conditions where there is a lack of endogenous nitric oxide (NO). Therefore, NO-releasing PDE5 inhibitors have been developed. Here we report the effect of such a compound, NCX-911, on the tone and nitrergic relaxations of rabbit corpus cavernosum in the absence or presence of a NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME; 500 microM). NCX-911 was found to be as potent as sildenafil at inducing relaxation of rabbit cavernosum (EC(50) values 997.8+/-195.7 and 1000.5+/-140.8 nM, respectively). The potency of NCX-911 was not altered, but that of sildenafil decreased five-fold in the presence of L-NAME (EC(50) values 1281.2+/-268.3 and 4959.1+/-882.1, nM respectively, P<0.001 for sildenafil). Both compounds potentiated nitrergic relaxations with similar potencies. These results suggest that NO-releasing PDE5 inhibitors could potentially be more useful than PDE5 inhibitors in the treatment of ED in conditions where there is a lack of endogenous NO.

Morphological, chemical and functional analysis of catuaba preparations

Fourteen commercial samples of the popular Brazilian aphrodisiac Catuaba specified as bark drugs of Anemopaegma, Erythroxylum and Trichilia species were examined for identity and purity. Only a minority of the examined Catuaba samples contained the crude drugs claimed on the labels. More than half of the products were adulterated with different crude drugs. The majority of the samples contained a bark originating from Trichilia catigua. The TLC fingerprints confirmed the heterogeneity, in 50% of the samples tropane alkaloids of various concentrations were detected. TLC and HPLC methods for separation and identification of the tropane alkaloids were developed and their analytical data (RF values, retention times, ESI-MS) given. The structure elucidation of the two main alkaloids, catuabine D and its hydroxymethyl derivative, is presented. The 1H- and 13C-NMR assignments of these alkaloids are discussed with regard to literature data. Neither aqueous nor methanolic extracts of the Trichilia catigua reference material nor alkaloid-enriched fractions of commercial samples showed any effect on the rabbit corpus cavernosum in an in vitro test.

RhoA/Rho-kinase suppresses endothelial nitric oxide synthase in the penis: a mechanism for diabetes-associated erectile dysfunction

Significant impairment in endothelial-derived nitric oxide is present in the diabetic corpus cavernosum. RhoA/Rho-kinase may suppress endothelial nitric oxide synthase (eNOS). Here, we tested the hypothesis that RhoA/Rho-kinase contributes to diabetes-related erectile dysfunction and down-regulation of eNOS in the streptozotocin (STZ)-diabetic rat penis. Colocalization of Rho-kinase and eNOS protein was present in the endothelium of the corpus cavernosum. RhoA/Rho-kinase protein abundance and MYPT-1 phosphorylation at Thr-696 were elevated in the STZ-diabetic rat penis. In addition, eNOS protein expression, cavernosal constitutive NOS activity, and cGMP levels were reduced in the STZ-diabetic penis. To assess the functional role of RhoA/Rho-kinase in the penis, we evaluated the effects of an adeno-associated virus encoding the dominant-negative RhoA mutant (AAVTCMV19NRhoA) on RhoA/Rho-kinase and eNOS and erectile function in vivo in the STZ-diabetic rat. STZ-diabetic rats transfected with AAVCMVT19NRhoA had a reduction in RhoA/Rho-kinase and MYPT-1 phosphorylation at a time when cavernosal eNOS protein, constitutive NOS activity, and cGMP levels were restored to levels found in the control rats. There was a significant decrease in erectile response to cavernosal nerve stimulation in the STZ-diabetic rat. AAVT19NRhoA gene transfer improved erectile responses in the STZ-diabetic rat to values similar to control. These data demonstrate a previously undescribed mechanism for the down-regulation of penile eNOS in diabetes mediated by activation of the RhoA/Rho-kinase pathway. Importantly, these data imply that inhibition of RhoA/Rho-kinase improves eNOS protein content and activity thus restoring erectile function in diabetes.