Pigmented ciliary epithelium cells synthesize transthyretin in the rabbit eye

Abstract

Abstract: : Purpose:In addition to systemic clinical manifestations, various ocular symptoms are commonly recognized in transthyretin (TTR) related familial amyloidotic polyneuropathy (FAP). It has been well documented that the retinal pigmented epithelium (RPE) cells alone secretes TTR and the TTR from those cells causes amyloid deposition in the ocular tissues. However, the natural course of ocular symptoms of FAP patients suggests that the ciliary body cells may also synthesize TTR and contribute amyloid formation. The present study was to clarify the sites of TTR synthesis in the eyes in addition to RPE. Methods: We performed in situ hybridization (ISH) in paraffin–embedded tissue sections of rabbit eyes to detect the sites of TTR synthesis. Reverse transcription–polymerase chain reaction (RT–PCR) of the ciliary body or retina was performed to detect TTR mRNA. In addition, levels of TTR mRNA expression were quantified by real–time quantitative RT–PCR and G6PDH gene expression levels were used as an internal control. Results: ISH for the eyes revealed the presence of TTR mRNA not only in RPE cells but also in pigmented ciliary epithelium (PCE) cells. RT–PCR revealed that RPE cells expressed TTR mRNA higher than PCE cells. Real–time RT–PCR showed that the level of TTR mRNA expression in PCE cells was about one–fourth of those of RPE cells. Conclusions: TTR is synthesized from the PCE cells and the TTR may cause ocular manifestations, especially glaucoma in TTR related FAP patients.

Keywords: ciliary body • gene/expression