The role of Toll-like receptor 4 in high-glucose-induced inflammatory and fibrosis markers in human peritoneal mesothelial cells

Int Urol Nephrol. 2017 Jan;49(1):171-181. doi: 10.1007/s11255-016-1430-9. Epub 2016 Oct 8.


Purpose: High glucose stimulates peritoneal inflammation and extracellular matrix accumulation in human peritoneal mesothelial cells (HPMCs). However, the roles of Toll-like receptor 4 (TLR4) and TLR2 in high-glucose-induced inflammation and fibrosis in peritoneal dialysis (PD) remain unclear. This study aimed to evaluate the effect of high glucose on TLR2 and TLR4 expression in HPMCs and to assess their impact on peritoneal inflammatory and fibrosis markers.

Methods: Using cultured HPMCs, TLRs expression by high-glucose (50 mM) stimulation was assessed by quantitative real-time PCR. The association of reactive oxygen species (ROS) in high-glucose-induced TLR2 and TLR4 expression was measured by 2',7'-dichlorodihydrofluorescein diacetate staining with or without ROS inhibitor. In addition, the role of TLR2 and TLR4 on high-glucose-induced inflammatory and fibrosis markers including chemoattractant protein-1 (MCP-1), NF-κB, alpha-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-ß), and fibronectin was evaluated after inhibition of TLR2 and TLR4 by small-interfering RNA (siRNA) or anti-TLR4/TLR2 antibodies, respectively.

Results: High glucose induced TLR1, TLR2, and TLR4 mRNAs expressions. High-glucose-induced TLR4 and TLR2 mRNAs were associated partly with the generation of ROS. Inhibition of TLR4 attenuated the high-glucose-induced expression of MCP-1 mRNA and protein, MyD88 mRNA, nuclear NF-κB p65 protein, TGF-β, fibronectin, and α-SMA mRNA and protein. However, inhibition of TLR2 did not change the expression of MCP-1 mRNA and protein.

Conclusions: High glucose induces inflammatory and fibrosis markers in HPMCs partly through the TLR4/MyD88/NF-κB signaling pathway rather than TLR2. Therefore, TLR4 might be a therapeutic target for ameliorating peritoneal inflammation and fibrosis in PD.

Keywords: Human peritoneal mesothelial cells; Peritoneal dialysis; Peritoneal fibrosis; Toll-like receptors.

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Cells, Cultured
  • Chemokine CCL2 / genetics
  • Chemokine CCL2 / metabolism
  • Epithelial Cells / drug effects
  • Fibronectins / genetics
  • Fibronectins / metabolism
  • Fibrosis
  • Gene Expression / drug effects
  • Gene Knockdown Techniques
  • Glucose / pharmacology*
  • Humans
  • Inflammation / metabolism*
  • Myeloid Differentiation Factor 88 / genetics
  • Peritoneum / cytology*
  • Peritoneum / pathology*
  • RNA, Small Interfering / pharmacology
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • Toll-Like Receptor 1 / genetics
  • Toll-Like Receptor 2 / antagonists & inhibitors
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism*
  • Toll-Like Receptor 4 / antagonists & inhibitors
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism*
  • Transcription Factor RelA / metabolism
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism


  • ACTA2 protein, human
  • Actins
  • CCL2 protein, human
  • Chemokine CCL2
  • Fibronectins
  • MYD88 protein, human
  • Myeloid Differentiation Factor 88
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 1
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Transcription Factor RelA
  • Transforming Growth Factor beta
  • Glucose