Toll-like receptor (TLR)-2/4 expression in retinal ganglion cells in a high-glucose environment and its implications

Genet Mol Res. 2016 Apr 25;15(2). doi: 10.4238/gmr.15026998.

Abstract

Diabetic retinopathy (DR), a major complication of diabetes mellitus, is the leading cause of adult blindness. The Toll-like receptor (TLR) family is believed to be involved in the pathogenesis and progression of DR. Here, we investigated the expression profiles of TLR-2 and TLR-4 in retinal ganglion cells (RGCs), in an attempt to elucidate the role of these molecules in the etiology of DR. In vitro cultured RGCs were divided into control and high-glucose groups. The mRNA and protein levels of TLR-2, TLR-4, and nuclear factor (NF)-κB were detected by real-time PCR and western blotting. RGCs were further transfected with specific siRNA targeting TLR2/TLR4; the proliferation of transfected RGCs and their tumor necrosis factor (TNF)-α and interleukin (IL)-8 secretory capacity were analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and enzyme-linked immunosorbent assays (ELISA), respectively. In a high-glucose environment, TLR-2/4 expression was significantly upregulated in RGCs (while their viability decreased); additionally, NF-κB expression and secretion of TNF-α and IL-8 were significantly increased. Co-silencing of the TLR-2 and TLR-4 genes inhibited NF- κB expression and TNF-α/IL-8 secretion, while increasing the survival rate of RGCs. Therefore, a high-glucose environment can potentiate the expression of TLR-2 and TLR-4 in RGCs, activate the downstream signaling pathway, and increase the secretion of pro-inflammatory factors, thereby aggravating DR.

MeSH terms

  • Cell Line
  • Cell Survival / genetics
  • Diabetes Mellitus / genetics
  • Diabetes Mellitus / pathology
  • Diabetic Retinopathy / genetics*
  • Diabetic Retinopathy / pathology
  • Gene Expression Regulation / drug effects
  • Glucose / administration & dosage
  • Humans
  • Interleukin-8 / biosynthesis*
  • Interleukin-8 / genetics
  • NF-kappa B / genetics
  • Retinal Ganglion Cells / metabolism
  • Retinal Ganglion Cells / pathology
  • Signal Transduction / drug effects
  • Toll-Like Receptor 2 / biosynthesis
  • Toll-Like Receptor 2 / genetics*
  • Toll-Like Receptor 4 / biosynthesis
  • Toll-Like Receptor 4 / genetics*
  • Tumor Necrosis Factor-alpha / biosynthesis*
  • Tumor Necrosis Factor-alpha / genetics

Substances

  • CXCL8 protein, human
  • Interleukin-8
  • NF-kappa B
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha
  • Glucose