TGF-β1 protection against Aβ1-42-induced hippocampal neuronal inflammation and apoptosis by TβR-I

Neuroreport. 2018 Jan 17;29(2):141-146. doi: 10.1097/WNR.0000000000000940.

Abstract

Alzheimer's disease (AD), the most common chronic neurodegenerative disease, is pathologically characterized by the formation of neurofibrillary tangles because of hyperphosphorylation of tau protein and extracellular deposits of amyloid-β (Aβ) protein termed senile plaques. Recent studies indicate that neuronal apoptosis caused by chronic neuroinflammation is one of the important pathogenesis of AD. Transforming growth factor (TGF)-β1 is a pleiotropic cytokine with immunosuppressive and anti-inflammatory properties. However, it is poorly known whether the anti-inflammatory property of TGF-β1 is involved in a neuroprotection in AD. Here, an AD cell model of hippocampal neurons induced by Aβ1-42 was used to show an anti-inflammatory and neuroprotective effect of TGF-β1 through its receptor transforming growth factor-β receptor type I (TβR-I). As expected, Aβ1-42-induced an upregulation in neuronal expression of amyloid precursor protein (APP), tumor necrosis factor-α, cyclooxygenase-2, Bax, cleaved caspase-3, and cleaved caspase-9, and a downregulation in the expression of Bcl-2, as well as an increase in the number of NeuN/terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) double-positive cells. TGF-β1 pretreatment reduced the Aβ1-42-induced effects of upregulating APP, tumor necrosis factor-α, Bax, cleaved caspase-3 and cleaved caspase-9, and downregulating Bcl-2, in addition to increasing NeuNTUNEL cell number. TβR-I expression in hippocampal neurons was downregulated by Aβ1-42 exposure, but upregulated by TGF-β1 pretreatment. Silencing of the TβR-I gene in the neurons abolished the anti-inflammatory and antiapoptotic effects of TGF-β1 in the Aβ1-42-induced AD cell model. These findings suggest that TGF-β1 protects neurons against Aβ1-42-induced neuronal inflammation and apoptosis by activation of TβR-I.

MeSH terms

  • Amyloid beta-Peptides / administration & dosage
  • Amyloid beta-Peptides / metabolism
  • Amyloid beta-Peptides / toxicity*
  • Animals
  • Apoptosis / physiology
  • Caspase 3 / metabolism
  • Caspase 9 / metabolism
  • Cells, Cultured
  • Gene Expression Regulation
  • Hippocampus / metabolism*
  • Hippocampus / pathology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Neurons / metabolism*
  • Neurons / pathology
  • Neuroprotection / physiology*
  • Peptide Fragments / administration & dosage
  • Peptide Fragments / metabolism
  • Peptide Fragments / toxicity*
  • Protein Serine-Threonine Kinases / metabolism*
  • Rats, Sprague-Dawley
  • Receptor, Transforming Growth Factor-beta Type I
  • Receptors, Transforming Growth Factor beta / metabolism*
  • Transforming Growth Factor beta1 / administration & dosage
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • Amyloid beta-Peptides
  • Bax protein, rat
  • Peptide Fragments
  • Receptors, Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Tumor Necrosis Factor-alpha
  • amyloid beta-protein (1-42)
  • bcl-2-Associated X Protein
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type I
  • Tgfbr1 protein, rat
  • Casp3 protein, rat
  • Casp9 protein, rat
  • Caspase 3
  • Caspase 9