CCL5 via GPX1 activation protects hippocampal memory function after mild traumatic brain injury

Redox Biol. 2021 Oct:46:102067. doi: 10.1016/j.redox.2021.102067. Epub 2021 Jul 17.

Abstract

Traumatic brain injury (TBI) is a prevalent head injury worldwide which increases the risk of neurodegenerative diseases. Increased reactive oxygen species (ROS) and inflammatory chemokines after TBI induces secondary effects which damage neurons. Targeting NADPH oxidase or increasing redox systems are ways to reduce ROS and damage. Earlier studies show that C-C motif chemokine ligand 5 (CCL5) has neurotrophic functions such as promoting neurite outgrowth as well as reducing apoptosis. Although CCL5 levels in blood are associated with severity in TBI patients, the function of CCL5 after brain injury is unclear. In the current study, we induced mild brain injury in C57BL/6 (wildtype, WT) mice and CCL5 knockout (CCL5-KO) mice using a weight-drop model. Cognitive and memory functions in mice were analyzed by Novel-object-recognition and Barnes Maze tests. The memory performance of both WT and KO mice were impaired after mild injury. Cognition and memory function in WT mice quickly recovered after 7 days but recovery took more than 14 days in CCL5-KO mice. FJC, NeuN and Hypoxyprobe staining revealed large numbers of neurons damaged by oxidative stress in CCL5-KO mice after mTBI. NADPH oxidase activity show increased ROS generation together with reduced glutathione peroxidase-1 (GPX1) and glutathione (GSH) activity in CCL5-KO mice; this was opposite to that seen in WT mice. CCL5 increased GPX1 expression and reduced intracellular ROS levels which subsequently increased cell survival both in primary neuron cultures and in an overexpression model using SHSY5Y cell. Memory impairment in CCL5-KO mice induced by TBI could be rescued by i.p. injection of the GSH precursor - N-acetylcysteine (NAC) or intranasal delivery of recombinant CCL5 into mice after injury. We conclude that CCL5 is an important molecule for GPX1 antioxidant activation during post-injury day 1-3, and protects hippocampal neurons from ROS as well as improves memory function after trauma.

Keywords: CCL5; Glutathione peroxidase - 1 (GPX1); NADPH oxidase; Reactive oxygen species (ROS); Traumatic brain injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Concussion*
  • Chemokine CCL5
  • Glutathione Peroxidase / metabolism
  • Glutathione Peroxidase GPX1
  • Hippocampus / metabolism
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout

Substances

  • CCL5 protein, human
  • Ccl5 protein, mouse
  • Chemokine CCL5
  • Glutathione Peroxidase
  • Glutathione Peroxidase GPX1