Testosterone and Vascular Function in Aging

Androgen receptors are widely distributed in several tissues, including vascular endothelial and smooth muscle cells. Through classic cytosolic androgen receptors or membrane receptors, testosterone induces genomic and non-genomic effects, respectively. Testosterone interferes with the vascular function by increasing the production of pro-inflammatory cytokines and arterial thickness. Experimental evidence indicates that sex steroid hormones, such as testosterone modulate the synthesis and bioavailability of NO and, consequently, endothelial function, which is key for a healthy vasculature. Of interest, aging itself is accompanied by endothelial and vascular smooth muscle dysfunction. Aging-associated decline of testosterone levels is accompanied by age-related diseases, such as metabolic and cardiovascular diseases, indicating that very low levels of androgens may contribute to cardiovascular dysfunction observed in these age-related disorders or, in other words, that testosterone may have beneficial effects in the cardiovascular system. However, testosterone seems to play a negative role in the severity of renal disease. In this mini-review, we briefly comment on the interplay between aging and testosterone levels, the vascular actions of testosterone and its implications for vascular aging. Renal effects of testosterone and the use of testosterone to prevent vascular dysfunction in elderly are also addressed

Vascular mechanisms of post-COVID-19 conditions: rho-kinase is a novel target for therapy

BackgroundIn post-COVID-19 conditions (Long COVID), systemic vascular dysfunction is implicated but the mechanisms are uncertain, and treatment is imprecise.MethodsPatients convalescing after hospitalisation for COVID-19 and risk-factor matched controls underwent multisystem phenotyping using blood biomarkers, cardiorenal and pulmonary imaging, and gluteal subcutaneous biopsy (NCT04403607). Small resistance arteries were isolated and examined using wire myography, histopathology, immunohistochemistry, and spatial transcriptomics. Endothelium-independent (sodium nitroprusside) and -dependent (acetylcholine) vasorelaxation and vasoconstriction to the thromboxane A2 receptor agonist, U46619, and endothelin-1 (ET-1) in the presence or absence of a RhoA/Rho-kinase inhibitor (fasudil), were investigated.ResultsThirty-seven patients, including 27 (mean age 57 years, 48% women, 41% cardiovascular disease) three months post-COVID-19 and 10 controls (mean age 57 years, 20% women, 30% cardiovascular disease), were included. Compared with control responses, U46619-induced constriction was increased (p = 0.002) and endothelium-independent vasorelaxation was reduced in arteries from COVID-19 patients (p < 0.001). This difference was abolished by fasudil. Histopathology revealed greater collagen abundance in COVID-19 arteries (Masson's Trichrome (MT) 69.7% [95%CI: 67.8, 71.7]; picrosirius red 68.6% [95% CI: 64.4, 72.8]) versus controls (MT 64.9% [95%CI:59.4, 70.3] [p = 0.028]; picrosirius red 60.1% [95% CI: 55.4, 64.8], [p = 0.029]). Greater phosphorylated myosin light chain antibody-positive staining in vascular smooth muscle cells was observed in COVID-19 arteries (40.1%; 95% CI: 30.9, 49.3) vs. controls (10.0%; 95% CI: 4.4, 15.6) (p < 0.001). In proof-of-concept studies, gene pathways associated with extracellular matrix alteration, proteoglycan synthesis, and viral mRNA replication appeared to be upregulated.ConclusionPatients with post-COVID-19 conditions have enhanced vascular fibrosis and myosin light change phosphorylation. Rho-kinase activation represents a novel therapeutic target for clinical trials