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.

Fibroblast growth factor-2 induces astroglial and microglial reactivity in vivo.

A role for fibroblast growth factor-2 (FGF-2) has been proposed in mediating the glial response to injury in the central nervous system (CNS). We have tested this possibility in vivo, by injecting FGF-2 into the cerebrospinal fluid (CSF) of the brain ventricles of young rats and analysing glial cells in the anterior medullary velum (AMV), which partly roofs the IVth ventricle. FGF-2 was administered at two different doses, low FGF-2 (500 ng mL(-1) CSF) and high FGF-2 (10 microg mL(-1) CSF), and saline vehicle was injected in controls. Injections were performed twice daily for three days, commencing at postnatal day (P) 6, and AMV were analysed at P9, using immunohistochemistry and Western blotting. Glial cells were unaffected by treatment with saline or low FGF-2, whereas high FGF-2 induced reactive changes in glial cell types: (1) there was increased GFAP expression in astrocytes, demonstrated by Western blot and immunohistochemistry, and astrocytes appeared hypertrophic, with increased process thickness and number; (2) the number of ED1 labelled microglia/macrophages was doubled, from 47 +/- 6 to 114 +/- 17 cells per field (0.75 mm2; values are mean +/- SEM), and microglia appeared activated, with a multipolar and granular appearance; (3) NG2 positive glial cells appeared more fibrous and there was increased density of processes, although there was no significant increase in their number; (4) oligodendrocyte somata were enlarged and there was a loss of myelin sheaths. The results show that at high CSF titres of FGF-2 induce glial reactivity in vivo and support a role for FGF-2 in the pathology of CNS injury and EAE.