In vivo molecular markers for pro-inflammatory cytokine M1 stage and resident microglia in trimethyltin-induced hippocampal injury

Neurotox Res. 2014 Jan;25(1):45-56. doi: 10.1007/s12640-013-9422-3. Epub 2013 Sep 4.

Abstract

Microglia polarization to the classical M1 activation state is characterized by elevated pro-inflammatory cytokines; however, a full profile has not been generated in the early stages of a sterile inflammatory response recruiting only resident microglia. We characterized the initial M1 state in a hippocampal injury model dependent upon tumor necrosis factor (TNF) receptor signaling for dentate granule cell death. Twenty-one-day-old CD1 male mice were injected with trimethyltin (TMT 2.3 mg/kg, i.p.) and the hippocampus was examined at an early stage (24-h post-dosing) of neuronal death. Glia activation was assessed using a custom quantitative nuclease protection assay. We report elevated mRNA levels for glia response such as ionizing calcium-binding adapter molecule-1 and glial fibrillary acidic protein (Gfap); Fas, hypoxia inducible factor alpha, complement component 1qb, TNF-related genes (Tnf, Tnfaip3, Tnfrsfla); interleukin-1 alpha, Cd44, chemokine (C-C motif) ligand (Ccl)2, Cc14, integrin alpha M, lipocalin (Lcn2), and secreted phosphoprotein 1 (Spp1). These changes occurred in the absence of changes in matrix metalloproteinase 9 and 12, neural cell adhesion molecule, metabotropic glutamate receptor (Grm)3, and Ly6/neurotoxin 1 (Lynx1), as well as, a decrease in neurotrophin 3, glutamate receptor subunit epsilon (Grin)-2b, and neurotrophic tyrosine kinase receptor, type 3. The M2 anti-inflammatory marker, transforming growth factor beta-1 (Tgfb1) was elevated. mRNAs associated with early stage of injury-induced neurogenesis including fibroblast growth factor 21 and Mki67 were elevated. In the "non-injured" temporal cortex receiving projections from the hippocampus, Lynx1, Grm3, and Grin2b were decreased and Gfap increased. Formalin fixed-paraffin-embedded tissue did not generate a comparable profile.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Biomarkers
  • Cell Death
  • Cytokines / metabolism*
  • Hippocampus / drug effects*
  • Hippocampus / metabolism*
  • Hippocampus / pathology
  • Inflammation / genetics
  • Inflammation / metabolism
  • Male
  • Mice
  • Microglia / drug effects
  • Microglia / metabolism*
  • RNA, Messenger / metabolism
  • Temporal Lobe / drug effects
  • Temporal Lobe / metabolism
  • Trimethyltin Compounds / toxicity

Substances

  • Biomarkers
  • Cytokines
  • RNA, Messenger
  • Trimethyltin Compounds
  • trimethyltin