TLR4 inhibitor attenuates amyloid-β-induced angiogenic and inflammatory factors in ARPE-19 cells: Implications for age-related macular degeneration

Mol Med Rep. 2016 Apr;13(4):3249-56. doi: 10.3892/mmr.2016.4890. Epub 2016 Feb 15.

Abstract

Subretinally-deposited amyloid-β (Aβ) is an important factor in age‑related macular degradation (AMD) often leading to irreversible blindness in the elderly population. The molecular mechanism underlying Aβ deposition during AMD remains unclear. The expression of inflammatory and angiogenic factors was examined by treatment of retinal pigment epithelial (RPE) cells with the oligomeric form of Aβ (OAβ1-42). Changes in the mRNA expression levels of various cytokines was detected by the QuantiGenePlex 6.0 Reagent system, and the protein expression level was determined by western blotting. Culture supernatants were detected using a multiplex cytokine assay and enzyme-linked immunosorbent assays. The in vitro tube formation was evaluated by a Matrigel assay. The present study highlights that OAβ1‑42 activates the toll-like receptor 4 (TLR4), myeloid differentiation factor 88 and phosphorylation nuclear factor-κB signaling pathway in RPE cells. Additionally, it increased the mRNA and protein expression of interleukin (IL)-6, IL-8, IL-33, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and angiopoietin 2. Furthermore, the TLR4 inhibitor (COBRA) attenuated the expression of inflammatory and angiogenesis factors, particularly IL-6, IL-8, IL-33, bFGF and VEGF. When human umbilical vein endothelial cells (HUVECs) were co-cultured with the COBRA-treated RPE cell culture supernatant the length of the endothelial cell network (measured by calculating tip cell lengths of endothelial cells) was impaired when compared with the HUVECs that were co‑cultured with the cell supernatant exposed to OAβ1‑42. These results suggest that the TLR4-associated pathway may be a potential target for the treatment of AMD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid beta-Peptides / metabolism*
  • Angiopoietin-2 / metabolism
  • Blotting, Western
  • Cell Line
  • Cytokines / genetics
  • Cytokines / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Fibroblast Growth Factor 2 / metabolism
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Macular Degeneration / metabolism
  • Macular Degeneration / pathology
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / metabolism
  • Neovascularization, Physiologic
  • Toll-Like Receptor 4 / antagonists & inhibitors*
  • Toll-Like Receptor 4 / metabolism
  • Up-Regulation
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Amyloid beta-Peptides
  • Angiopoietin-2
  • Cytokines
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Toll-Like Receptor 4
  • Vascular Endothelial Growth Factor A
  • Fibroblast Growth Factor 2