Age‐associated intracellular superoxide dismutase deficiency potentiates dermal fibroblast dysfunction during wound healing

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Abstract
Reactive oxygen species (ROS) impair wound healing through destructive oxidation of intracellular proteins, lipids, and nucleic acids. Intracellular superoxide dismutase (SOD1) regulates ROS levels and plays a critical role in tissue homeostasis. Recent evidence suggests that age-associated wound healing impairments may partially result from decreased SOD1 expression. We investigated the mechanistic basis by which increased oxidative stress links to age-associated impaired wound healing. Fibroblasts were isolated from unwounded skin of young and aged mice, and myofibroblast differentiation was assessed by measuring α-smooth muscle actin and collagen gel contraction. Excisional wounds were created on young and aged mice to study the healing rate, ROS levels, and SOD1 expression. A mechanistic link between oxidative stress and fibroblast function was explored by assessing the TGF-β1 signaling pathway components in young and aged mice. Age-related wounds displayed reduced myofibroblast differentiation and delayed wound healing, consistent with a decrease in the in vitro capacity for fibroblast-myofibroblast transition following oxidative stress. Young fibroblasts with normal SOD1 expression exhibited increased phosphorylation of ERK in response to elevated ROS. In contrast, aged fibroblasts with reduced SOD1 expression displayed a reduced capacity to modulate intracellular ROS. Collectively, age-associated wound healing impairments are associated with fibroblast dysfunction that is likely the result of decreased SOD1 expression and subsequent dysregulation of intracellular ROS. Strategies targeting these mechanisms may suggest a new therapeutic approach in the treatment of chronic non-healing wounds in the aged population.
Funding Information
  • Japan Society for the Promotion of Science (KAKENHI, 15K10958)
  • National Institute on Aging (R01‐AG025016)
  • Oak Foundation

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