The Phosphodiesterase Type 5 Inhibitor Sildenafil Improves DNA Stability and Redox Homeostasis in Systemic Sclerosis Fibroblasts Exposed to Reactive Oxygen Species

Abstract

Systemic sclerosis (SSc) is a multi-system connective tissue disease characterized by the increased deposition of extracellular matrix proteins such as collagen and fibronectin. Although the pathogenesis is not completely understood, a number of studies suggest that free radicals could be the major contributors to the disease. Indeed, different studies demonstrated how oxidative stress could contribute to the fibrotic process activation at the level of the skin and visceral organs. Emerging evidences highlight the beneficial effects of sildenafil, a phosphodiesterase type 5 inhibitor (PDE5i), which protects different cell lines from the cell damage induced by reactive oxygen species (ROS). These data make sildenafil a good candidate for therapeutic treatment aimed to protect biological macromolecules against oxidative damage, thus preserving cell viability. The purpose of this study was to evaluate the sensitivity of SSc dermal fibroblasts to an oxidative insult and the ability for sildenafil to prevent/reduce the DNA damage due to ROS action. Additionally, we evaluated the capacity for sildenafil to influence redox homeostasis and cytotoxicity, as well as cell proliferation and cell cycle progression. We demonstrated that SSc fibroblasts have an increased sensitivity to a pro-oxidant environment in comparison to healthy controls. The sildenafil treatment reduced ROS-induced DNA damage, counteracted the negative effects of ROS on cell viability and proliferation, and promoted the activity of specific enzymes involved in redox homeostasis maintenance. To our knowledge, in this report, we demonstrate, for the first time, that sildenafil administration prevents ROS-induced instability in human dermal fibroblasts isolated by SSc patients. These results expand the use of PDE5i as therapeutic agents in SSc by indicating a protective role in tissue damage induced by oxidative insult.

Effect of Tadalafil Administration on Redox Homeostasis and Polyamine Levels in Healthy Men with High Level of Physical Activity

“…These compounds have recently showed antioxidant effects in different organs of animal models. This effect is achieved through the reduction of endogenous superoxide formation and the increase in the antioxidant enzymes’ activity [ 9 , 10 , 11 , 13 , 15 , 16 ]. Moreover, an improved mitochondrial integrity [ 11 , 21 ], a decreased tissue malondialdehyde and increased SOD and GPx activity levels were found following tadalafil administration [ 17 , 18 , 19 , 20 , 21 , 22 ].…”

“…Recently, in addition to their role in the treatment of pathologies, in vitro and in vivo studies reported that PDE5Is (e.g., sildenafil, vardenafil, tadalafil) also possess antioxidant effects in different tissues/organs [ 9 , 10 , 11 , 12 , 13 , 14 ]. For instance, it has been shown that sildenafil citrate has protective effects against oxidative stress by inhibiting free radical formation and supporting antioxidant redox systems [ 13 , 15 ].…”

“…Recently, in addition to their role in the treatment of pathologies, in vitro and in vivo studies reported that PDE5Is (e.g., sildenafil, vardenafil, tadalafil) also possess antioxidant effects in different tissues/organs [ 9 , 10 , 11 , 12 , 13 , 14 ]. For instance, it has been shown that sildenafil citrate has protective effects against oxidative stress by inhibiting free radical formation and supporting antioxidant redox systems [ 13 , 15 ]. Interestingly, in a model of a fetal rat brain with an ischemia/reperfusion injury, tadalafil was found to be more effective than sildenafil in reducing the endogenous superoxide formation by increasing the antioxidant enzyme activity of glutathione peroxidase (GPx) [ 16 ].…”

Moringa oleifera Leaf Extract Upregulates Nrf2/HO-1 Expression and Ameliorates Redox Status in C2C12 Skeletal Muscle Cells

“…Intracellular superoxide dismutase activity was measured using a commercial assay kit (Cayman Chemical Company, Ann Arbor, MI, USA) following the manufacturer’s instructions. Results were expressed as units/milligrams of protein tested [ 35 ].…”

“…Thiobarbituric acid reactive substances. TBARS levels were assayed by spectrophotometric analysis [ 35 ]. The methodology measured malondialdehyde (MDA) and other aldehydes produced by lipid peroxidation induced by hydroxyl-free radicals.…”