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-ß1). The mRNA of the cells was collected at 0, 24, 36, 48, and 72 hours after stimulation with TGF-ß1 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.

Bioinformatics-Based Identification of Potential Hypoxia-Related Genes Associated With Peyronie's Disease.

Hypoxia is one of the most important predisposing conditions for Peyronie's disease (PD) and the pathogenetic mechanism is yet to be completely elucidated. This study applied bioinformatic approaches to select candidate hypoxia-related genes involved in the pathogenesis of PD. The Gene Expression Omnibus (GEO) data set GSE146500 was introduced to compare the transcriptional profiling between normal and PD samples. The differential expression of hypoxia-related gene was determined with R software. On the selected candidate genes, further functional analyses were applied, including protein-protein interactions (PPIs), gene correlation, gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. A total of 66 candidate genes (24 candidates overexpressed in PD and 42 showing reduced expression in PD) were distinguished according to the differential expression between human fibroblast cells from normal and PD patients. The interactions among these candidate genes were recognized according to PPI analysis. The functional enrichment analyses revealed the potential modulatory functions of the candidate genes in some major biological processes, especially in glycolysis/gluconeogenesis and carbon metabolism. The findings would facilitate further study on the pathogenesis of PD, which might consequently promote the improvement of clinical strategies against PD.

Significant familial clustering of Peyronie's disease in close and distant relatives.

BACKGROUND: Peyronie's disease (PD) has previously been observed to co-aggregate in a small number of first-degree relative pairs (e.g., father-son). However, the familial aggregation of PD in more distant relatives, as well as the aggregation of Dupuytren's disease (DD) in probands and relatives, has not been thoroughly investigated. OBJECTIVE: This study explored the evidence for familial clustering of PD and DD in close and distant relatives. MATERIALS AND METHODS: The Utah Population Database, which includes genealogy information linked to electronic medical records (available since 1995), was used to identify men and their relatives with PD and DD based on ICD9/10 codes. All cases were required to have high-quality genealogy data. We estimated relative risk (RR) of PD and DD in first- through fifth-degree relatives compared to matched population rates of disease. We also investigated the average relatedness of cases compared to the average relatedness of sets of matched controls. Outcome measures include estimation of relative risk and excessive relatedness as measured by a Genealogical Index of Familiality (GIF) analysis. RESULTS: We analyzed 307 individuals with PD, and their first- through fifth-degree relatives. Approximately 0.12% of the population had PD, 95% of these were diagnosed over the age of 30 years (age range: 10-92 years), and 1.3% of PD probands had a comorbid diagnosis of DD. RR estimates for PD were significant for first- and fifth-degree relatives. RR estimates for DD were significant only for probands. The average relatedness of cases was significantly greater than matched controls, even after removing first- and second-degree relatives. We also found that 74.9% of identified PD probands belonged to pedigrees with a statistical excess of PD. CONCLUSION: Despite the low prevalence of PD in our healthcare records, the results provide evidence that support a genetic contribution to at least a subset of PD cases.

Whole-Genome Sequencing Identifies Novel Heterozygous Mutation in ALMS1 in Three Men With Both Peyronie's and Dupuytren's Disease.

Peyronie's Disease (PD) is estimated to occur in up to 13% of males and has been associated with Dupuytren's Disease (DD). We identified 3 men with PD/DD and hypothesized that there may be a genetic association between the 2 diseases. Blood samples were collected from the participants and sent for whole genome sequencing. A rare non-synonymous mutation in the ALMS1 gene was identified in 3 men. Interestingly, ALMS1 is associated with TGF-b, and aberrant fibrosis. This pilot study generates the hypothesis that mutations in ALMS1 may predispose patients to development of PD/DD.

Downregulation of miR-29b is associated with Peyronie's disease.

BACKGROUND: Peyronie's disease (PD) is characterized by the formation of fibrous plaque in tunica albuginea, causing several problems in patients. The etiology of this disease is not fully understood, and there are few effective treatments. To better understand the molecular pathways of PD, we studied miR-29b, a microRNA that could be involved with this illness. MicroRNAs are endogenous molecules that act by inhibiting messenger RNA. MiR-29b regulates 11 of 20 collagen genes and the TGF-ß1 gene, which are related to PD progression. METHODS: We compared miR-29b expression in 11 patients with PD and 14 patients without PD (control group). For the patients with PD, we utilized samples from the fibrous plaque (n = 9), from the tunica albuginea (n = 11), and from the corpus cavernosum (n = 8). For the control group, we utilized samples from the tunica albuginea (n = 14) and from the corpus cavernosum (n = 10). MiR-29b expression was determined by q-PCR. RESULTS: We found a downregulation of miR-29b in the fibrous plaque, tunica albuginea and corpus cavernosum of patients with PD in comparison with the control group (p = 0.0484, p = 0.0025, and p = 0.0016, respectively). CONCLUSION: Although our study has a small sample, we showed for the first time an evidence that the downregulation of miR-29b is associated with PD.

RNA-sequencing profiling analysis of pericyte-derived extracellular vesicle-mimetic nanovesicles-regulated genes in primary cultured fibroblasts from normal and Peyronie's disease penile tunica albuginea.

BACKGROUND: Peyronie's disease (PD) is a severe fibrotic disease of the tunica albuginea that causes penis curvature and leads to penile pain, deformity, and erectile dysfunction. The role of pericytes in the pathogenesis of fibrosis has recently been determined. Extracellular vesicle (EV)-mimetic nanovesicles (NVs) have attracted attention regarding intercellular communication between cells in the field of fibrosis. However, the global gene expression of pericyte-derived EV-mimetic NVs (PC-NVs) in regulating fibrosis remains unknown. Here, we used RNA-sequencing technology to investigate the potential target genes regulated by PC-NVs in primary fibroblasts derived from human PD plaque. METHODS: Human primary fibroblasts derived from normal and PD patients was cultured and treated with cavernosum pericytes isolated extracellular vesicle (EV)-mimetic nanovesicles (NVs). A global gene expression RNA-sequencing assay was performed on normal fibroblasts, PD fibroblasts, and PD fibroblasts treated with PC-NVs. Reverse transcription polymerase chain reaction (RT-PCR) was used for sequencing data validation. RESULTS: A total of 4135 genes showed significantly differential expression in the normal fibroblasts, PD fibroblasts, and PD fibroblasts treated with PC-NVs. However, only 91 contra-regulated genes were detected among the three libraries. Furthermore, 20 contra-regulated genes were selected and 11 showed consistent changes in the RNA-sequencing assay, which were validated by RT-PCR. CONCLUSION: The gene expression profiling results suggested that these validated genes may be good targets for understanding potential mechanisms and conducting molecular studies into PD.

Fibroproliferative disorders and diabetes: Understanding the pathophysiologic relationship between Peyronie's disease, Dupuytren disease and diabetes.

Introduction: Fibrosis is characterized by dysregulation and accumulation of extracellular matrix. Peyronie's disease and Dupuytren disease are fibroproliferative disorders of the tunica albuginea of the penis and fascia of the hand, respectively. Chronic hyperglycaemia due to diabetes mellitus can also lead to tissue injury and fibrosis. A meta-analysis has shown a relationship between Dupuytren disease and diabetes (overall odds ratio, 3.1; 95% confidence interval, 2.7-3.5). This review explores commonalities in the pathogenesis of Peyronie's disease, Dupuytren disease and diabetes. Methods: A search of the PubMed database was conducted using the search terms "diabetes" AND "Peyronie's disease"; and "diabetes" AND "Dupuytren." Results: Genome-wide association and gene expression studies conducted with tissue from people with Peyronie's disease or Dupuytren disease identified signalling pathways associated with wingless-type mammary-tumour virus integration site signalling, extracellular matrix modulation and inflammation. Biochemical studies confirmed the importance of these pathways in the pathogenesis of fibrosis with Peyronie's disease and Dupuytren disease. Dysregulation of matrix metalloproteinase activity associated with extracellular matrix breakdown was implicated in fibroproliferative complications of diabetes and in the aetiology of Peyronie's disease and Dupuytren disease. A notable percentage of people with diabetes have comorbid Peyronie's disease and/or Dupuytren disease. Conclusions: Studies have not been performed to identify fibroproliferative pathways that all 3 conditions might have in common, but data suggest that common pathways are involved in the fibroproliferative processes of Peyronie's disease, Dupuytren disease, and diabetes.

The Etiology of Peyronie's Disease: Pathogenesis and Genetic Contributions.

INTRODUCTION: Peyronie's disease (PD) is a chronic fibrosing condition that contributes to penile deformity, curvature, and pain. Initial familial studies demonstrated potential genetic links to PD. Since that time, very few investigations have significantly advanced the science in this area. Hence, there is a large opportunity and significant need to better study the underlying genomics and pathogenesis of PD. AIM: To summarize the current genomic literature relevant to PD. METHODS: A review was performed of all PubMed-indexed literature from 1970-2018 relating to the pathophysiology and genetics of PD. Key findings were categorically summarized to include epidemiology, risk factors, inheritance patterns, chromosomal instability, genetic associations, epigenetics, differential gene expression, and preclinical models of PD. MAIN OUTCOME MEASURES: Summary of the current literature on the genetics of PD. RESULTS: PD is a common condition and has several known risk factors and comorbid disease associations. Although men with PD are believed to be genetically predisposed, there are likely several subtypes of the condition, each with varied pathophysiological disorders and contributing factors. Available data suggest that PD is associated with underlying genetic instability, including dysregulation of genes relating to fibrosis and cellular degradation, thus, resulting in abnormal plaque development and penile deformity. Preclinical models, including cell cultures and rat models, demonstrate several consistencies with PD clinical and histopathologic characteristics; however, an ideal model with spontaneous development of PD is lacking. CONCLUSION: Based on limited data, PD likely represents a heterogeneous condition, with both heritable and environmentally-driven epigenetic factors contributing to its development and progression. However, there remains a significant gap in the literature on the underlying cause and pathophysiology of the condition, suggesting a substantial need for further investigation and study. Sharma KL, Alom M, Trost L. The Etiology of Peyronie's Disease: Pathogenesis and Genetic Contributions. Sex Med Rev 2020;8:314-323.

Erectile Dysfunction and Peyronie's Disease: Genetic Diseases?

There is considerable interest in understanding the genetics of erectile dysfunction (ED) and Peyronie's disease (PD) in an effort to identify novel therapeutic and preventative targets. Initial support for a genetic component of ED and PD was derived from familial aggregation studies. Candidate gene studies have suggested an association between polymorphisms of eNOS and ED and between TGF-ß1 and PD. More recently, several genome-wide association studies have suggested an association between single-nucleotide polymorphisms of the SIM1 gene and ED. The development of models and functional assays that are able to explore these potential pathways implicated in ED and PD is pivotal for future studies. We highlight the current literature that supports a genetic component for ED and PD. PATIENT SUMMARY: There is great interest in understanding the genetic underpinnings of erectile dysfunction and Peyronie's disease. Candidate gene studies and genome-wide association studies have set a foundation for future work; however, we have yet to determine a true genetic cause. A better understanding of the genetics of these conditions will help advance novel therapeutics and preventative strategies.

Pathophysiology and Future Therapeutic Perspectives for Resolving Fibrosis in Peyronie's Disease.

INTRODUCTION: Peyronie's disease (PD) is a debilitating affliction for the male population, causing severe curvatures to the erect penis and erectile dysfunction in about 50% of men. This deviation of the penis significantly impairs sexual intercourse and causes depression and strains in the relationship. As of today, medical treatment options are few and far between, with surgery remaining as the sole reliable treatment. AIM: To give a general overview regarding fibrosis and the specific role of extracellular matrix, macrophages, and myofibroblasts in PD. Additionally, we will provide an overview of past and present research and how this has shaped our vision concerning the pathophysiology of PD. METHODS: We performed a non-systematic literature review using the search terms "fibrosis," "pathophysiology," "myofibroblast," "extracellular matrix," "Peyronie's disease," and "drug discovery." MAIN OUTCOME MEASURE: We assessed current knowledge regarding fibrosis in PD and the possibility to use this knowledge for new treatment options. RESULTS: Interpreting findings from the most recent next-generation sequencing, in vitro and in vivo PD research, we provide novel insights for the pathophysiology of PD. Using this knowledge, we will attempt to provide future directions for PD research and drug discovery, which is urgently needed, because its treatment has essentially been stagnating for about 30 years. CONCLUSION: Historically, PD has not been studied as widely as kidney, lung, or hepatic fibrosis, and our knowledge of its pathophysiology still remains relatively obscure. Nonetheless, recent breakthroughs using stem cells, next-generation sequencing, and phenotypical screening assays bring us several steps closer to filling the gaps in our knowledge. In the near future, clinical trials will prove essential to translate this plethora of preclinical data into usable tools that can improve the lives of many of our patients. Milenkovic U, Ilg MM, Cellek S, et al. Pathophysiology and Future Therapeutic Perspectives for Resolving Fibrosis in Peyronie's Disease. Sex Med Rev 2019;7:679-689.

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.

The Genetic Basis of Peyronie Disease: A Review.

INTRODUCTION: Peyronie disease (PD) is a progressive fibrotic disorder of the penile tunica albuginea that results in fibrotic penile plaques and can lead to penile deformity. Characterized by aberrant fibrosis resulting in part from the persistence of myofibroblasts and altered gene expression, the molecular factors underpinning PD and other related fibrotic diatheses are just being elucidated. A genetic link to PD was first identified three decades ago using pedigree analyses. However, the specific genetic factors that predispose patients to aberrant fibrosis remain unknown, and the relations between these fibrotic conditions and other heritable diseases, including malignancy, are uncharacterized. AIM: To review the current landscape linking molecular and genetic factors to aberrant fibrosis in PD and related fibrotic diatheses, including Dupuytren disease. METHODS: Review and evaluation of the literature from 1970 to the present for genetic factors associated with PD were performed. MAIN OUTCOME MEASURES: Data describing the genetic factors associated with PD were obtained. RESULTS: We describe the known structural chromosomal abnormalities and single-nucleotide polymorphisms associated with fibrotic diatheses and discuss the spectrum of differential gene expression data comparing normal tissues with those derived from men with PD or Dupuytren disease. We discuss epigenetic mechanisms that might regulate gene expression and alter predisposition to fibrosis. CONCLUSION: Although the current understanding of the genetic factors associated with PD is limited, significant advances have been made during the past three decades. Further research is necessary to provide a more comprehensive understanding of the landscape of genetic factors responsible for the development of PD.

Alternative Splicing of IGF1 Gene as a Potential Factor in the Pathogenesis of Peyronie's Disease.

BACKGROUND/AIM: Peyronie's disease (PD) is a fibrotic entity for which the pathogenetic mechanism remains unclear and if resulting in severe deformity, its treatment is only surgical. In this study we investigated the possible role of insulin-like growth factor 1 (IGF1) expression in the pathogenesis of PD. MATERIALS AND METHODS: Tissue samples were obtained from plaques of 24 patients with PD. The expression of IGF1 isoforms was investigated using quantitative real-time polymerase chain reaction and immunofluorescence. RESULTS: All IGF1 isoform gene expression (Ea, Eb and Ec) were found significantly decreased in the affected tunica albuginea, compared to normal tunica albuginea, with Ec showing the greatest decrease. Staining of tissue sections with an antibody against IGF1Ec confirmed greater expression of IGF1Ec isoform in normal tunica albuginea. CONCLUSION: The expression of all IGF1 alternative spliced isoforms is decreased in patients with PD, suggestive of its possible participation in the pathophysiology of PD.

Silencing histone deacetylase 2 using small hairpin RNA induces regression of fibrotic plaque in a rat model of Peyronie's disease.

OBJECTIVES: To examine the therapeutic effect of adenovirus encoding histone deacetylase 2 (HDAC2) small hairpin RNA (Ad-HDAC2 shRNA) in a rat model of Peyronie's disease (PD) and to determine the mechanisms by which HDAC2 knockdown ameliorates fibrotic responses in primary fibroblasts derived from human PD plaque. MATERIALS AND METHODS: Rats were distributed into four groups (n = 6 per group): age-matched controls without treatment; rats in which PD has been induced (PD rats) without treatment; PD rats receiving a single injection of control adenovirus encoding scrambled small hairpin RNA (Ad-shRNA) (day 15; 1 × 10(8) pfu/0.1 mL phosphate-buffered saline [PBS]); and PD rats receiving a single injection of Ad-HDAC2 shRNA (day 15; 1 × 10(8) pfu/0.1 mL PBS) into the lesion. PD-like plaque was induced by repeated intratunical injections of 100 µL each of human fibrin and thrombin solutions on days 0 and 5. On day 30, the penis was harvested for histological examination. Fibroblasts isolated from human PD plaque were pretreated with HDAC2 small interfering (si)RNA (100 pmoL) and then stimulated with transforming growth factor (TGF)-ß1 (10 ng/mL) to determine hydroxyproline levels, procollagen mRNA, apoptosis and protein expression of poly(ADP-ribose) polymerase 1 (PARP1) and cyclin D1. RESULTS: We observed that Ad-HDAC2 shRNA decreased inflammatory cell infiltration, reduced transnuclear expression of phospho-Smad3 and regressed fibrotic plaque of the tunica albuginea in PD rats in vivo. siRNA-mediated silencing of HDAC2 significantly decreased the TGF-ß1-induced transdifferentiation of fibroblasts into myofibroblasts and collagen production, and induced apoptosis by downregulating the expression of PARP1, and decreased the expression of cyclin D1 (a positive cell-cycle regulator) in primary cultured fibroblasts derived from human PD plaque in vitro. CONCLUSION: Specific inhibition of HDAC2 with RNA interference may represent a novel targeted therapy for PD.

Cytokine gene expression in the tunica albuginea of patients with Peyronie's disease. Pilot study with a control group.

INTRODUCTION AND OBJECTIVE: Cytokines may be involved in the pathogenesis of Peyronie's disease (PD). In this case, biological drugs, acting on specific cytokines, could be adopted in the pharmacological treatment of the disease. MATERIALS AND METHODS: Twenty PD patients and 8 patients affected by congenital recurvatum penis (control group) who underwent corporoplasty were enrolled in the study. Histological examination and measurement by Real Time PCR of the expression of the encoding genes for IL-2, IL-4, IL-6, IL-10, IL-13, TGF-ß, TNF-α and IFN-γ were performed on the removed tunica albuginea (TA). For the normalization of data GAPDH (glucerldehyde-3fosfatehydrogenase) and GUSB (ß-glucuronidase), housekeeping genes were used. The analysis of the data was performed using the comparative method of ΔCt. The results were reported with the Fold of induction (FOI) method. RESULTS: The histological exams of TA showed only fibrous tissue without cavernous tissue. The analysis of gene expression of IL-6, IL-10, IFN-γ and TGF-ß1 showed in all samples very low levels. The levels were lower in PD patients although the differences were not statistically significant. An exception was represented by TGF-ß that showed a higher level in PD patients, although not statistically significant. The expression of IL-4, IL-13 and TNF-α was undetectable. CONCLUSIONS: The expressions of cytokines in TA of PD patients compared to those of the controls do not show any significant difference. A bias of our study is that the groups were not age-matched. This is a bias already present in similar experiences and due to the different pathogenesis of the diseases. Cytokines promoting inflammation resulted undetectable and do not seem to be involved in PD pathogenesis. The higher level of TGF-ß, a pro-fibrotic cytokine, detected in PD could explain the presence of fibrotic tissue. Presently, there is no data suggesting a possible role of biological drugs in PD.

WNT2 locus is involved in genetic susceptibility of Peyronie's disease.

INTRODUCTION: Peyronie's disease (PD) is a fibromatosis of the penis, with a pathology very similar to what is seen in the hand (palmar fascia) in Dupuytren's disease (DD). Recently, we performed a genome-wide association study and identified nine genetic loci containing common variants associated with DD. Seven of these loci mapped within or near genes of the canonical WNT pathway and each locus yielded relatively large odds ratios (ORs) for DD disease status. AIM: Given the clinical overlap between PD and DD, we examined whether the nine DD susceptibility loci are also involved in PD. METHODS: An association study was performed using a case/control design. From 2007 to 2010, we prospectively included 111 men who had been clinically diagnosed with PD. Control subjects (N = 490 males) were randomly drawn from a population-based cohort from the same region of the Netherlands. Allele frequencies in the 111 PD cases and 490 controls were compared using a 1-degree-of-freedom basic chi-square test. A P value < 0.05 after Bonferroni correction for the nine tested single nucleotide polymorphisms (SNPs) was considered statistically significant (i.e., P < 0.0056). MAIN OUTCOME MEASURE: Association of genetic markers (SNPs) with PD. RESULTS: We observed significant association with SNP rs4730775 at the wingless-type MMTV integration site family member 2 (WNT2) locus on chromosome 7 (P = 0.0015, OR 0.61), but found no evidence for the other eight loci being involved with PD despite the large effect size seen for some of these variants in DD. The WNT2 association was even more significant after we removed 15 patients with comorbid DD. CONCLUSIONS: WNT2 is a susceptibility locus for PD and our finding provides evidence for a partly shared genetic susceptibility between PD and DD.

Comparison of apoptotic gene expression profiles between Peyronie's disease plaque and tunica albuginea.

BACKGROUND: The fibrotic plaques of Peyronie/s disease and other localized fibrotic conditions have been considered to be the result of an abnormal wound healing process. The potential role of regulatory disorders of apoptosis in abnormal wound healing may also play a role in the development of Peyronie's disease. OBJECTIVES: To examine the phenomenon of apoptosis in Peyronie's disease, authors quantified differential levels of gene expression of apoptotic proteins, Fas, Fas Ligand, Bcl-2, p53, Caspase 3 and 8 in Peyronie's plaque and tunica albuginea. MATERIAL AND METHODS: Eight patients with Peyronie's disease undergoing surgical correction of the curvature had biopsy specimens taken from both the Peyronie's plaque and normal tunica albuginea. Messenger RNA expression of the apoptotic proteins in the plaque and normal tunica was measured by reverse transcriptase PCR. RESULTS: Apoptotic gene expression was lower than the housekeeping gene's in half of the tunica albuginea samples and two thirds of the plaque samples. Overall mRNA expressions in the plaque were not significantly different from the normal tunica albuginea. CONCLUSIONS: The fibrotic plaques of Peyronie's disease and other localized fibrotic conditions have been considered to be the result of an abnormal wound healing process. The potential role of regulatory disorders of apoptosis in abnormal wound healing may also play a role in the development of Peyronie's disease. In this study, the lower expression of apoptotic genes may cause the persistence of collagen producing cells which were up-regulated for unknown reasons and consequently result in plaque formation. Similar expression levels of apoptotic genes in both tunica albuginea and Peyronie's plaques may be due to the generalized physiopathologic alterations in tunica albuginea that lead to plaque formation at a vulnerable region subjected to recurrent traumas.

Rat as an animal model for Peyronie's disease research: a review of current methods and the peer-reviewed literature.

While the exact mechanism of Peyronie's disease (PD) remains an enigma, the pathophysiology of PD is considered to be multifactorial, with interactions of genetic predisposition, trauma, tissue inflammation and aberrant wound healing. A non-systematic review of the existing English language literature pertaining to the use of rodent models in the evaluation of PD was performed using the Medline database. Multiple free-text searches were performed on key words: animal models of PD, transforming growth factor ß1 (TGF ß1), tunical and/or corporal fibrosis, subtunical injection and penile myofibroblasts. The most frequently reported models of PD can be classified as TGF ß1, fibrin and surgical trauma-induced models. In vitro studies using Peyronie's fibroblast culture media have also provided further insights into cellular mechanism of PD. At the present time, the research in PD is hampered by the lack of universally accepted animal model and this is likely attributed to the limited insight into PD mechanisms and the difficulties faced by current animal models to truly represent the complexity and complete spectrum of human disease.

Upregulation of mRNA expression of MCP-1 by TGF-beta1 in fibroblast cells from Peyronie's disease.

INTRODUCTION: Peyronie's disease (PD) is a localized connective tissue disorder of the penile tunica albuginea (TA) with a still obscure etiopathology. Recent studies from our laboratory have demonstrated differences in Smad3 and Smad4 gene expression of PD-fibroblasts and non-PD-fibroblasts after stimulation with recombinant TGF-beta1 for 1 h. In the present study, we investigated gene expression of Smad2-Smad4 and Smad7 up to 6 h after stimulation with TGF-beta1. As a positive control, MCP-1 gene expression was monitored. MATERIALS AND METHODS: Cells with fibroblast characteristics were isolated from seven PD plaques and three TA controls. The cells were incubated with recombinant TGF-beta1 for 2-6 h and expression of Smad2-Smad4, Smad7, and monocyte chemotactic protein-1 (MCP-1) was determined by quantitative real-time PCR. RESULTS: TGF-beta1 treatment resulted in a statistically significant up-regulation of Smad7 and MCP-1 gene expression. Smad7 expression was increased after 2 h (P < 0.001) and was still high after 4 h (P < 0.05). No significant differences between fibroblasts from PD-patients compared to non-PD-patients were observed. MCP-1 peaked after 4 h (P < 0.001) and remained high up to 6 h (P < 0.01). PD-fibroblasts revealed a significantly increased MCP-1 gene expression compared to non-PD-fibroblasts (P = 0.013) after 2 h and remained significantly different also after 6 h (P = 0.038). Gene expression of Smad2-Smad4 did not change during stimulation with TGF-beta1. CONCLUSION: In conclusion, analysis of MCP-1 expression might be a useful marker for Peyronie's disease.

A new mouse model of Peyronie's disease: an increased expression of hypoxia-inducible factor-1 target genes during the development of penile changes.

Peyronie's disease (PD) is characterized by an inflammatory response beneath the tunica albuginea with fibroblast proliferation forming a thickened fibrous plaque that may cause pain, penile curvature and erectile dysfunction. The progression of the PD plaque may eventually lead to calcification or ossification. Current therapeutic success is often unsatisfactory because of limited insight into disease mechanisms. Research has been hampered by the lack of a universally accepted animal model. We describe an animal model of spontaneous PD in tight skin (Tsk) mice, a C57Bl/6J subline that reproduces with age important features of the human disease (fibrous plaque formation, penile bending and areas of chondroid metaplasia with heterotopic ossification). Histological analysis demonstrated an evident structural disorganization of the tunica albuginea with excessive accumulation of type I collagen. At 12 months of age, fibrous plaques with areas of chondroid metaplasia and heterotopic ossification characterized Tsk penises. The up-regulation of hypoxia-inducible factor-1 (HIF-1) leads to an increased downstream expression of HIF-1 target genes, such as TGFbeta and iNOS. These factors, together with some PDGF family members, can cause collagen deposition in Tsk penises. They can also influence chondrocyte differentiation and heterotopic bone formation. In conclusion, hypoxia, HIF-1 and HIF-1 target genes appear to play an important role in the pathogenesis of PD in Tsk mice. This mouse model that is the first example of naturally occurring model of PD in laboratory animals may aid in the identification of signalling pathways crucial for PD and should facilitate the designing and testing of new therapeutic interventions.