Ferroptosis is involved in corpus cavernosum smooth muscle cells impairment in diabetes mellitus-induced erectile dysfunction

Identification and validation of new fatty acid metabolism-related mechanisms and biomarkers for erectile dysfunction

Background

Erectile dysfunction (ED) is a common condition affecting middle-aged and elderly men.

Aim

The study sought to investigate differentially expressed fatty acid metabolism-related genes and the molecular mechanisms of ED.

Methods

The expression profiles of GSE2457 and GSE31247 were downloaded from the Gene Expression Omnibus database and merged. Differentially expressed genes (DEGs) between ED and normal samples were obtained using the R package limma. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of DEGs were conducted using the R package clusterProfiler. Fatty acid metabolism-related DEGs (FAMDEGs) were further identified and analyzed. Machine learning algorithms, including Lasso (least absolute shrinkage and selection operator), support vector machine, and random forest algorithms, were utilized to identify hub FAMDEGs with the ability to predict ED occurrence. Coexpression analysis and gene set enrichment analysis of hub FAMDEGs were performed.

Outcome

Fatty acid metabolism-related functions (such as fatty acid metabolism and degradation) may play a vital role in ED.

Results

In total, 5 hub FAMDEGs (Aldh2, Eci2, Acat1, Acadl, and Hadha) were identified and found to be differentially expressed between ED and normal samples. Gene set enrichment analysis identified key pathways associated with these genes. The area under the curve values of the 5 hub FAMDEGs for predicting ED occurrence were all >0.8.

Clinical Translation

Our results suggest that these 5 key FAMDEGs may serve as biomarkers for the diagnosis and treatment of ED.

Strengths and Limitations

The strengths of our study include the use of multiple datasets and machine learning algorithms to identify key FAMDEGs. However, limitations include the lack of validation in animal models and human tissues, as well as research on the mechanisms of these FAMDEGs.

Conclusion

Five hub FAMDEGs were identified as potential biomarkers for ED progression. Our work may prove that fatty acid metabolism-related genes are worth further investigation in ED.

Identifying potential cross-talk signatures for the occurrence of atherosclerosis in diabetic erectile dysfunction

BACKGROUND

Erectile dysfunction and atherosclerosis are common cardiovascular complications in diseases. Clinical associations between erectile dysfunction and atherosclerosis have been noticed, but the specific mechanisms are not illustrated adequately.

OBJECTIVES

The aim of the study was to further mine associated pathological mechanisms and genetic alterations of atherosclerosis in diabetes mellitus-related erectile dysfunction.

MATERIALS AND METHODS

Significant atherosclerosis-related genes were identified from transcriptome data of diabetes mellitus-related erectile dysfunction and atherosclerosis-related gene sets from DisGeNET and GeneCard databases. Functional enrichment and immune infiltration analyses were performed to clarify the biological roles and pathways as well as immune responses of significant atherosclerosis-related gene sets. A protein-protein interaction network was constructed, and gene clusters were performed. Then, data of diabetic plaques and high-glucose cavernosum endothelial cells were analyzed for validation. And hub atherosclerosis-related gene sets were identified. Finally, expressed pattern of hub atherosclerosis-related gene sets were explored by single-cell profiling and immune analysis.

RESULTS

In total, 202 significant atherosclerosis-related gene sets including 100 upregulated and 102 downregulated genes were identified. These genes were related to endothelial cell migration, inflammatory response, regulation of oxidative stress, and immune response. In immune infiltration, immature dendritic cells and monocytes showed differential expression between the diabetes mellitus-related erectile dysfunction and control groups, A protein-protein interaction network containing 135 nodes was constructed. A hub atherosclerosis-related gene set signature consisting of HBEGF, LOX, NQO1, and VLDLR was obtained by multi-omics validation. In addition, Functional enrichment analysis revealed that hub atherosclerosis-related gene sets were involved in oxidoreductase activity and extracellular matrix organization.

DISCUSSION AND CONCLUSION

We explored atherosclerosis-related genetic changes and signaling pathways in diabetes mellitus-related erectile dysfunction. HBEGF, LOX, NQO1, and VLDLR were identified as hub atherosclerosis-related gene sets. These may serve as potential biomarkers for the clinical management of atherosclerosis and preventing further cardiovascular risks in diabetes mellitus-related erectile dysfunction.

Low androgen levels induce ferroptosis of rat penile cavernous endothelial cells

Background

Endothelial dysfunction caused by low androgen levels in penile tissue can lead to erectile dysfunction. The exact mechanism of endothelial dysfunction has not been thoroughly studied.

Objective

The study sought to verify whether low androgen levels induce ferroptosis of endothelial cells in rat penile tissue.

Methods

Rat penile cavernous endothelial cells (CP-R133) were divided into a no-androgen group (Dihydrotestosterone (DHT): 0 nmol/L), very low-androgen group (DHT: 0.1 nmol/L), low-androgen group (DHT: 1 nmol/L), DHT = 10 nmol/L group, DHT (0 nmol/L) + ferrostatin-1 (Fer-1) group, DHT (0.1 nmol/L) + Fer-1 group, DHT (1 nmol/L) + Fer-1 group, DHT (10 nmol/L) + Fer-1 group. Cell viability, intracellular ferrous ion (Fe2+), malondialdehyde (MDA), GSH into oxidized glutathione (GSSG), reactive oxygen species (ROS), nitric oxide (NO), transferrin receptor 1 protein (TfR1), solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), acyl-CoA synthetase long-chain family member 4 (ACSL4), endothelial nitric oxide synthase (eNOS), and phospho-eNOS (p-eNOS) were detected.

Outcomes

Low androgen levels could induce ferroptosis of rat penile cavernous endothelial cells in vivo by upregulating the expressions of TfR1 and ACSL4 and downregulating the expressions of SLC7A11 and GPX4.

Results

Cell viability, the levels of glutathione (GSH), NO, SLC7A11, GPX4, and p-eNOS/eNOS in the DHT = 0 nmol/L group were lower than those in the other groups (P < .05). The levels of Fe2+, ROS, MDA, GSSG, TfR1, and ACSL4 in the DHT = 0 nmol/L group were higher than those in the other groups (P < .05). Cell viability and the levels of GSH, NO, SLC7A11, GPX4, and p-eNOS/eNOS in the DHT = 1 nmol/L group were lower than those in the DHT (1 nmol/L) + Fer-1 group, DHT = 10 nmol/L group, and DHT (10 nmol/L) + Fer-1 group (P < .05). The levels of Fe2+, ROS, MDA, GSSG, TfR1, and ACSL4 in the DHT = 1 nmol/L group were higher than those in the DHT (1 nmol/L) + Fer-1 group, DHT = 10 nmol/L group, and DHT (10 nmol/L) + Fer-1 group (P < .05).

Clinical Implications

A ferroptosis inhibitor might be a novel drug for treating erectile dysfunction caused by low androgen level.

Strengths and Limitations

The results of this study need to be further confirmed in in vitro and in human studies. Meanwhile, further investigation is needed to clarify whether low androgen levels affect ferroptosis of rat penile cavernous smooth muscle and nerve cells.

Conclusion

Low androgen levels can induce ferroptosis of endothelial cells in rat penile tissue. Inhibition of ferroptosis can reverse endothelial dysfunction caused by low androgen levels.

A review of experimental techniques for erectile function researches and development of medical technology using animal erectile dysfunction models in sexual and reproductive medicine

Background

Erectile dysfunction (ED) is one of the causes of male infertility and is a disease that requires treatment. The first‐line drugs for ED are phosphodiesterase 5 (PDE‐5) inhibitors, and further treatment options are currently limited. Medical technologies, such as genetic control and regenerative medicine, are developing rapidly. Research on erectile function is progressing rapidly, coupled with technological innovations in other areas.

Methods

A PubMed search using the keywords “animal (rat, mouse, rabbit, dog, and monkey)” and “erectile” was conducted, and all relevant peer‐reviewed English results were evaluated.

Main findings

The methods for evaluating erectile function include intracavernous pressure (ICP) measurements, isometric tension studies, and dynamic infusion cavernosometry. Papers also reported various disease model animals for the study of diabetes mellitus, cavernous nerve injury, and drug‐induced ED.

Conclusion

Basic research on ED treatment has progressed rapidly over the past 20 years. In particular, research on the mechanism of ED has been accelerated by the publication of a study on the evaluation of erectile function using ICP measurements in rats. In addition, molecular biological experimental methods such as polymerase chain reaction (PCR) and western blotting have become relatively easy to perform due to technological progress, thus advancing research development.

Overexpression of PRDX2 in Adipose-Derived Mesenchymal Stem Cells Enhances the Therapeutic Effect in a Neurogenic Erectile Dysfunction Rat Model by Inhibiting Ferroptosis

Neurogenic erectile dysfunction (NED) is a common and serious complication after pelvic surgery. The clinical translation of adipose-derived mesenchymal stem cell (ADSC) therapies in NED remains a major challenge due to their low survival rate and limited therapeutic effect. Peroxiredoxin 2 (PRDX2) is a member of the peroxidase family that exerts its therapeutic effects by inhibiting oxidative stress (OS) and ferroptosis, and PRDX2 is expected to enhance the therapeutic effect of ADSCs in treating NED. The purpose of this study was to investigate whether PRDX2 could improve the survival of ADSCs and determine whether overexpression of PRDX2 in ADSCs (PRDX2-ADSCs) could enhance the therapeutic effect of NED. This study investigated the potential role of PRDX2-ADSCs through a NED model induced by bilateral cavernous nerve injury (BCNI) and three in vitro models established by H₂O₂-stimulated ADSCs, H₂O₂-stimulated corpus cavernosum smooth muscle cells (CCSMCs), and RSL3-stimulated CCSMCs. We found that PRDX2 could significantly improve the viability of ADSCs by suppressing apoptosis and OS in H₂O₂-stimulated ADSCs. We also found that BCNI triggered ferroptosis of the corpus cavernosum, which was manifested by increased reactive oxygen species (ROS), total iron content, and MDA as well as decreased SOD and GSH. Our results further demonstrated changes in the expression of key proteins (GPX4 and ACSL4) in the ferroptosis pathway, whereas PRDX2-ADSCs ameliorated BCNI-induced erectile dysfunction and ferroptosis of the corpus cavernosum in NED rats. Consistently, PRDX2-ADSCs attenuated OS in H₂O₂-stimulated CCSMCs and inhibited ferroptosis in RSL3-stimulated CCSMCs, as evidenced by the decrease in ROS, total iron content, and MDA and the increase in SOD and GSH together with changes in ferroptosis-related protein (GPX4 and ACSL4) expression. In conclusion, overexpression of PRDX2 in ADSCs enhanced the therapeutic effect in a rat model of neurogenic erectile dysfunction by inhibiting ferroptosis via regulation of the GPX4/ACSL4 axis.

Comparison of characteristics between Chinese diabetes mellitus-induced erectile dysfunction populations and non-diabetes mellitus-induced erectile dysfunction populations: A cross-sectional study

BACKGROUND

Erectile dysfunction (ED) is a common disease in adult men, and diabetes is an independent risk factor for ED. However, there are few reports on the distinction between diabetes mellitus-induced erectile dysfunction (DMED) and non-DMED features, as well as ED features of varying severity in the two groups.

METHODS

A total of 365 ED patients treated at two clinics in China from 2019 to 2022 were included. Questionnaires of the International Index of Erectile Function (IIEF-5), Erectile Hardness Score (EHS), Premature Ejaculation Diagnostic Tool (PEDT), Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder-7 (GAD-7) were administered to the patients. They were divided into three groups according to the IIEF-5 score: 5-7 for severe ED, 8-11 for moderate ED, and 12-21 for mild ED. In addition, the patient's age, weight, height, fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), total testosterone (TT) and other indicators were also collected. Statistical analysis was performed using SPSS 26, comparing all parameters between groups.

RESULTS

Age (P<0.001), height (P=0.009), body mass index (BMI) (P=0.002), PEDT (P<0.001), FBG (P<0.001), FSH (P<0.001), TG (P<0.001), TT (P<0.001) and triglyceride-glucose index (TyG) (P<0.001) were significantly different between diabetic ED and nondiabetic ED subjects. The trend test in the nondiabetic ED population found a negative correlation between the IIEF-5 score and PHQ-9 (P for trend=0.15). Multivariate ordinal logistic regression in the diabetic ED population showed that elevated LH OR=11.37 (95% CI: 0.966, 3.897) and elevated PRL OR=4.10 (95% CI: 0.410, 2.411) were associated with an increased risk of more severe ED.

CONCLUSIONS

The aetiology, demographic parameters, degree of premature ejaculation, and related biochemical tests were significantly different between the DMED and non-DMED populations.