Alpha-Tocopherol Protects Human Dermal Fibroblasts by Modulating Nitric Oxide Release, Mitochondrial Function, Redox Status, and Inflammation

Skin Pharmacol Physiol. 2022;35(1):1-12. doi: 10.1159/000517204. Epub 2021 Jul 8.

Abstract

Background: The altered balance between oxidants/antioxidants and inflammation, changes in nitric oxide (NO) release, and mitochondrial function have a role in skin aging through fibroblast modulation. Tocopherol is promising in counteracting the abovementioned events, but the effective mechanism of action needs to be clarified.

Objective: The aim of this study was to examine the effects of α-tocopherol on cell viability/proliferation, NO release, mitochondrial function, oxidants/antioxidants, and inflammation in human dermal fibroblasts (HDF) subjected to oxidative stress.

Methods: HDF were treated with H2O2 in the presence or absence of 1-10 μM α-tocopherol. Cell viability, reactive oxygen species (ROS), NO release, and mitochondrial membrane potential were measured; glutathione (GSH), superoxide dismutase (SOD)-1 and -2, glutathione peroxidase-1 (GPX-1), inducible NO synthase (iNOS), and Ki-67 were evaluated by RT-PCR and immunofluorescence; cell cycle was analyzed using FACS. Pro- and anti-inflammatory cytokine gene expression was analyzed through qRT-PCR.

Results: α-Tocopherol counteracts H2O2, although it remains unclear whether this effect is dose dependent. Improvement of cell viability, mitochondrial membrane potential, Ki-67 expression, and G0/G1 and G2/M phases of the cell cycle was observed. These effects were accompanied by the increase of GSH content and the reduction of SOD-1 and -2, GPX-1, and ROS release. Also, iNOS expression and NO release were inhibited, and pro-inflammatory cytokine gene expression was decreased, confirming the putative role of α-tocopherol against inflammation.

Conclusion: α-Tocopherol exerts protective effects in HDF which underwent oxidative stress by modulating the redox status, inflammation, iNOS-dependent NO release, and mitochondrial function. These observations have a potential role in the prevention and treatment of photoaging-related skin cancers.

Keywords: Mitochondrial function; Nitric oxide release; Oxidative stress; Photoaging; Reactive oxygen species; α-Tocopherol.

MeSH terms

  • Antioxidants / metabolism
  • Antioxidants / pharmacology
  • Fibroblasts / metabolism
  • Humans
  • Hydrogen Peroxide
  • Inflammation / drug therapy
  • Mitochondria / metabolism
  • Nitric Oxide*
  • Oxidation-Reduction
  • Oxidative Stress
  • Reactive Oxygen Species
  • alpha-Tocopherol* / pharmacology

Substances

  • Antioxidants
  • Reactive Oxygen Species
  • Nitric Oxide
  • Hydrogen Peroxide
  • alpha-Tocopherol