The neonatal Fc receptor is expressed by human retinal pigment epithelial cells and is downregulated by tumour necrosis factor-alpha

Br J Ophthalmol. 2011 Jun;95(6):864-8. doi: 10.1136/bjo.2010.187930. Epub 2011 Jan 7.

Abstract

Background/aims: The neonatal Fc receptor (FcRn) protects immunoglobulin G (IgG) from catabolism, controls its transport between cell layers and extends its serum half-life. In the human, vitreous IgG can be found, but how vitreous IgG is processed or transported is currently unknown. The FcRn is a candidate molecule to regulate these processes. The authors examined FcRn expression and regulation in human retinal pigment epithelium (RPE) cells.

Methods: In three primary RPE cell cultures (from three donor eyes) and in the human RPE cell line ARPE-19, FcRn and beta-2-microglobulin (β2M) mRNA levels were determined by real-time quantitative PCR. FcRn protein expression was analysed by western blot studies. Stimulation experiments were performed with recombinant human tumour necrosis factor (TNF)-α and interferon (IFN)-γ. HT-29, THP-1 and HeLa cell lines were used as FcRn positive and negative non-ocular controls, respectively.

Results: Expression of FcRn mRNA and protein was demonstrated in all three RPE cultures. After stimulation with TNF-α, FcRn expression is downregulated in RPE cells and upregulated in HT-29 and THP-1 cells. IFN-γ has no effect on FcRn expression in RPE cells.

Conclusions: Human RPE cells express FcRn. The proinflammatory cytokine TNF-α downregulates FcRn expression. The authors speculate that the FcRn may play a pivotal role in the immune privilege of the human eye.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cell Line
  • Cells, Cultured
  • Down-Regulation
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • HT29 Cells
  • HeLa Cells
  • Histocompatibility Antigens Class I / genetics
  • Histocompatibility Antigens Class I / metabolism*
  • Humans
  • RNA, Messenger / metabolism
  • Receptors, Fc / genetics
  • Receptors, Fc / metabolism*
  • Retinal Pigment Epithelium / cytology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Necrosis Factor-alpha / pharmacology*
  • beta 2-Microglobulin / metabolism*

Substances

  • Histocompatibility Antigens Class I
  • RNA, Messenger
  • Receptors, Fc
  • Tumor Necrosis Factor-alpha
  • beta 2-Microglobulin
  • Fc receptor, neonatal