Expression of Neonatal Fc Receptor in the eye.

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Invest Ophthalmol Vis Sci 2014 Mar 19; 55(3):1607-1615.






Purpose: The neonatal Fc receptor (FcRn) plays a critical role in the homeostasis and degradation of immunoglobulin G (IgG). It mediates the transport of IgG across epithelial cell barriers and recycles IgG in endothelial cells back into the blood stream. These functions critically depend on the binding of FcRn to the Fc domain of IgG. The half-life and distribution of intravitreally injected anti-VEGF molecules containing IgG-Fc domains might therefore be affected by FcRn expressed in the eye. In order to establish whether FcRn - Fc(IgG) interactions may occur in the eye, we studied the mRNA and protein distribution of FcRn in postmortem ocular tissue. Methods: We used qPCR to study mRNA expression of the transmembrane chain of FcRn (FCGRT) in retina, optic nerve, retinal pigment epithelium (RPE)/choroid plexus, ciliary body/iris plexus, lens, cornea and conjunctiva isolated from mouse, rat, pig and human postmortem eyes and used immunohistochemistry to determine the pattern of FcRn expression in FCGRT-transgenic mouse and human eyes. Results: In all four tested species Fcgrt mRNA was expressed in the retina, RPE/choroid/ and the ciliary body/iris, while immunohistochemistry documented FcRn protein expression in the ciliary body epithelium, macrophages and endothelial cells in the retinal and choroidal vasculature. Conclusions: Our results demonstrate that FcRn has the potential to interact with IgG-Fc domains in the ciliary epithelium, retinal and choroidal vasculature, which might affect the half-life and distribution of intravitreally injected Fc-carrying molecules. Invest Ophthalmol Vis Sci 2014 Mar 19; 55(3):1607-1615.