Clarifying the Relative Impacts of Vascular and Nerve Injury That Culminate in Erectile Dysfunction in a Pilot Study Using a Rat Model of Prostate Irradiation and a Thrombopoietin Mimetic

The role of mechano-regulated YAP/TAZ in erectile dysfunction

Phosphodiesterase type 5 inhibitors (PDE5is) constitute the primary therapeutic option for treating erectile dysfunction (ED). Nevertheless, a substantial proportion of patients, approximately 30%, do not respond to PDE5i treatment. Therefore, new treatment methods are needed. In this study, we identified a pathway that contributes to male erectile function. We show that mechano-regulated YAP/TAZ signaling in smooth muscle cells (SMCs) upregulates adrenomedullin transcription, which relaxed the SMCs to maintain erection. Using single-nucleus RNA sequencing, we investigated how penile erection stretches the SMCs, inducing YAP/TAZ activity. Subsequently, we demonstrate that YAP/TAZ plays a role in erectile function and penile rehabilitation, using genetic lesions and various animal models. This mechanism relies on direct transcriptional regulation of adrenomedullin by YAP/TAZ, which in turn modulates penile smooth muscle contraction. Importantly, conventional PDE5i, which targets NO-cGMP signaling, does not promote erectile function in YAP/TAZ-deficient ED model mice. In contrast, by activating the YAP/TAZ-adrenomedullin cascade, mechanostimulation improves erectile function in PDE5i nonrespondent ED model rats and mice. Furthermore, using clinical retrospective observational data, we found that mechanostimulation significantly promotes erectile function in patients irrespective of PDE5i use. Our studies lay the groundwork for exploring the mechano-YAP/TAZ-adrenomedullin axis as a potential target in the treatment of ED.

Pathway analysis of microarray data from corpora cavernosal tissue of patients with a prostatectomy or Peyronie disease in comparison with a cavernous nerve-injured rat model of erectile dysfunction

INTRODUCTION

Patients with a prostatectomy are at high risk of developing erectile dysfunction (ED) that is refractory to phosphodiesterase type 5 inhibitors. The cavernous nerve (CN) is frequently damaged during prostatectomy, causing loss of innervation to the penis. This initiates corpora cavernosal remodeling (apoptosis and fibrosis) and results in ED.

AIM

To aid in the development of novel ED therapies, the current aim was to obtain a global understanding of how signaling mechanisms alter in the corpora cavernosa with loss of CN innervation that results in ED.

METHODS

Microarray and pathway analysis were performed on the corpora cavernosal tissue of patients with a prostatectomy (n = 3) or Peyronie disease (control, n = 3). Results were compared with an analysis of a Sprague-Dawley rat CN injury model (n = 10). RNA was extracted by TRIzol, DNase treated, and purified by a Qiagen Mini Kit. Microarray was performed with the Human Gene 2.0 ST Array and the RU34 rat array. Differentially expressed genes were identified through several analytic tools (ShinyGO, Ingenuity, WebGestalt) and databases (GO, Reactome). A 2-fold change was used as the threshold for differential expression.

OUTCOMES

Pathways that were altered (up- or downregulated) in response to CN injury in the prostatectomy patients and a rat CN injury model were determined.

RESULTS

Microarray identified 197 differentially expressed protein-coding genes in the corpora cavernosa from the prostatectomy cohort, with 100 genes upregulated and 97 genes downregulated. Altered signaling pathways that were identified that affect tissue morphology included the following: neurologic disease, cell death and survival, tissue and cellular development, skeletal and muscle development and disorders, connective tissue development and function, tissue morphology, embryonic development, growth and proliferation, cell-to-cell signaling, and cell function and maintenance. These human pathways have high similarity to those observed in the CN-injured rat ED model.

CLINICAL IMPLICATIONS

Significant penile remodeling continues in patients long after the acute surgical injury to the CN takes place, offering the opportunity for clinical intervention to reverse penile remodeling and improve erectile function.

STRENGTHS AND LIMITATIONS

Understanding how signaling pathways change in response to CN injury and how these changes translate to altered morphology of the corpora cavernosa and ensuing ED is critical to identify strategic targets for therapy development.

CONCLUSION

Altered signaling in pathways that regulate tissue homeostasis, morphogenesis, and development was identified in penes of patients with a prostatectomy, and competitive forces of apoptosis and proliferation/regeneration were found to compete to establish dominance after CN injury. How these pathways interact to regulate penis tissue homeostasis is a complex process that requires further investigation.

A flavonoid derivative of icariside II (YS-10) improves erectile dysfunction in radiation-injured rats via oxidative stress pathway

Background

We explored the preventive effect and mechanism of YS-10, a novel synthesized flavonoid derivative based on the structure of icariside II (ICA II), on a rat model of radiation-induced erectile-dysfunction (Ri-ED).

Methods

Eighteen 10-week-old male Sprague-Dawley (SD) rats were randomly divided into 3 groups. Six rats were used as the control group (Control), and the remaining 12 were given a single X-ray irradiation of 20 Gy in the prostate and then randomly divided into the radiation injury group (Ri-ED group) and YS-10 treatment group (Ri-ED+YS-10, 2.5 mg/kg/day). After 4 weeks of drug administration and a 2-week drug washout period in the YS-10 treatment group, the erectile function of the animals was evaluated, and the tissues were collected for histopathological analysis and detection of oxidative stress indicators.

Results

After radiation injury, the ratio of maximum intracavernosal pressure (ICP) to mean arterial pressure (MAP), the number of neuronal nitric oxide synthase (n-NOS) positive nerve fibers in the penis cavernosa, endothelial cell content, and n-NOS and endothelial nitric oxide synthase (e-NOS) proteins in the Ri-ED group were significantly lower than those in control group. Compared with the control group, the Ri-ED group had lower superoxide dismutase (SOD) levels and higher malondialdehyde (MDA) levels. Compared with the Ri-ED group, the YS-10 group had a significant increase in the ratio of ICP/MAP in the corpus cavernosum (0.59±0.06 vs. 0.43±0.06, P<0.01), the number of n-NOS positive nerve fibers, and the content of endothelial cells. The protein content of n-NOS and e-NOS in the corpus cavernosum increased and could significantly reduce the level of MDA (2.67±0.27 vs. 3.25±0.21, P<0.05).

Conclusions

As a novel ICA II derivative, YS-10 could significantly improve the erectile dysfunction and pathological damage in rats caused by radiation injury, and its mechanism may be related to the improvement of radiation-induced oxidative stress.

Swallowing dysfunction following radiation to the rat mylohyoid muscle is associated with sensory neuron injury

Radiation-based treatments for oropharyngeal and hypopharyngeal cancers result in impairments in swallowing mobility, but the mechanisms behind the dysfunction are not clear. The purpose of this study was to determine if we could establish an animal model of radiation-induced dysphagia in which mechanisms could be examined. We hypothesized that 1) radiation focused at the depth of the mylohyoid muscle would alter normal bolus transport and bolus size and 2) radiation to the mylohyoid muscle will induce an injury/stress-like response in trigeminal sensory neurons whose input might modulate swallow. Rats were exposed to 48 or 64 Gy of radiation to the mylohyoid given 8 Gy in 6 or 8 fractions. Swallowing function was evaluated by videofluoroscopy 2 and 4 wk following treatment. Neuronal injury/stress was analyzed in trigeminal ganglion by assessing activating transcription factor (ATF)3 and GAP-43 mRNAs at 2, 4, and 8 wk post treatment. Irradiated rats exhibited decreases in bolus movement through the pharynx and alterations in bolus clearance. In addition, ATF3 and GAP-43 mRNAs were upregulated in trigeminal ganglion in irradiated rats, suggesting that radiation to mylohyoid muscle induced an injury/stress response in neurons with cell bodies that are remote from the irradiated tissue. These results suggest that radiation-induced dysphagia can be assessed in the rat and radiation induces injury/stress-like responses in sensory neurons.NEW & NOTEWORTHY Radiation-based treatments for head and neck cancer can cause significant impairments in swallowing mobility. This study provides new evidence supporting the possibility of a neural contribution to the mechanisms of swallowing dysfunction in postradiation dysphagia. Our data demonstrated that radiation to the mylohyoid muscle, which induces functional deficits in swallowing, also provokes an injury/stress-like response in the ganglion, innervating the irradiated muscle.

The thrombopoietin mimetic JNJ-26366821 increases megakaryopoiesis without affecting malignant myeloid proliferation

Thrombocytopenia remains a challenge in myeloid malignancies, needing safer and more effective therapies. JNJ-26366821, a pegylated synthetic peptide thrombopoietin (TPO) mimetic not homologous to endogenous TPO, has an in-vitro EC50 of 0.2 ng/mL for the TPO receptor and dose dependently elevates platelets in volunteers. We demonstrate that JNJ-26366821 increases megakaryocytic differentiation and megakaryocytic colony formation in healthy controls and samples from myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). JNJ-26366821 had no effect on proliferation of malignant myeloid cell lines at doses up to 1000 ng/mL and malignant patient-derived mononuclear cells showed no increased cell growth or leukemic colony formation capacity at concentrations between 0.2 ng/mL and 10 ng/mL. Furthermore, JNJ-26366821 did not enhance in-vivo engraftment of leukemic cells in an AML xenotransplantation murine model. Our results show that JNJ-26366821 stimulates megakaryopoiesis without causing proliferation of the malignant myeloid clones in MDS/AML and provides the rationale for clinical testing of JNJ-26366821 in myeloid malignancies.