C5a and toll-like receptor 4 crosstalk in retinal pigment epithelial cells

Mol Vis. 2015 Sep 29:21:1122-9. eCollection 2015.

Abstract

Purpose: To investigate the effect of the complement activation product C5a on toll-like receptor (TLR) 4-induced responses in RPE cells.

Methods: Confluent cultures of human RPE cells (ARPE-19) were stimulated with C5a, lipopolysaccharide (LPS), or a combination of the two. The expression of TLR4 was determined by real-time PCR and flow cytometry. Cytokine profiles were determined by real-time PCR and enzyme-linked immunosorbent assay (ELISA). The phosphorylation of p38, ERK 1/2, and JNK was measured by flow cytometry.

Results: C5a stimulation enhanced the expression of TLR4 in a dose- and time-dependent manner. C5a was able to stimulate the production of TLR4-induced IL-6 and IL-8 by ARPE-19 cells. Blocking experiments showed that the effect of C5a on cytokine production was mediated via C5aR. ERK1/2, but not JNK or p38, were involved in the production of IL-6 and IL-8.

Conclusions: The results indicate that C5a can induce the TLR4 expression and enhance the production of TLR4-induced IL-6 and IL-8 by ARPE-19. The effect of C5a on cytokine production was mediated by C5aR and the phosphorylation of ERK1/2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Complement C5a / metabolism
  • Complement C5a / pharmacology*
  • Dose-Response Relationship, Drug
  • Drug Combinations
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects*
  • Epithelial Cells / immunology
  • Gene Expression Regulation
  • Humans
  • Interleukin-6 / genetics
  • Interleukin-6 / immunology
  • Interleukin-8 / genetics
  • Interleukin-8 / immunology
  • Lipopolysaccharides / pharmacology*
  • MAP Kinase Kinase 4 / genetics
  • MAP Kinase Kinase 4 / immunology
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / immunology
  • Mitogen-Activated Protein Kinase 3 / genetics
  • Mitogen-Activated Protein Kinase 3 / immunology
  • Phosphorylation
  • Receptor, Anaphylatoxin C5a / genetics
  • Receptor, Anaphylatoxin C5a / immunology
  • Retinal Pigment Epithelium / cytology
  • Retinal Pigment Epithelium / drug effects*
  • Retinal Pigment Epithelium / immunology
  • Signal Transduction
  • Toll-Like Receptor 4 / genetics*
  • Toll-Like Receptor 4 / immunology
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / immunology

Substances

  • C5AR1 protein, human
  • Drug Combinations
  • IL6 protein, human
  • Interleukin-6
  • Interleukin-8
  • Lipopolysaccharides
  • Receptor, Anaphylatoxin C5a
  • TLR4 protein, human
  • Toll-Like Receptor 4
  • Complement C5a
  • MAPK1 protein, human
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4