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The neonatal Fc receptor is expressed by human retinal pigment epithelial cells and is downregulated by tumour necrosis factor-alpha
  1. Kiki van Bilsen1,2,
  2. P Martin van Hagen1,2,
  3. Jeroen Bastiaans2,3,
  4. Jan C van Meurs3,
  5. Tom Missotten3,
  6. Robert W Kuijpers4,
  7. Herbert Hooijkaas2,
  8. Gemma M Dingjan2,
  9. G Seerp Baarsma3,
  10. Willem A Dik2
  1. 1Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
  2. 2Department of Immunology, Erasmus University Medical Center, Rotterdam, The Netherlands
  3. 3Rotterdam Eye Hospital, Rotterdam, The Netherlands
  4. 4Department of Ophthalmology, Erasmus University Medical Center, Rotterdam, The Netherlands
  1. Correspondence to Kiki van Bilsen, Department of Internal Medicine/Clinical Immunology, Erasmus MC, University Medical Center, s-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands; c.vanbilsen{at}erasmusmc.nl

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.

  • RPE
  • FcRn
  • IgG
  • TNF-alpha
  • retina
  • immunology

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Footnotes

  • Funding Supported by ‘Stichting Wetenschappelijk Onderzoek Oogziekenhuis—Professor Dr Flieringa’ (SWOO-Flieringa), grant 2008-05.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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