Analysis of the abnormal expression and structure of transthyretin in the vitreous of patients with pathological myopia

Abstract

Objective To detect structures and levels of transthyretin (TTR) in the vitreous of pathological myopia patients.Methods It was a experimental study.TTR concentrations in the vitreous of pathological myopia patients complicated by macular detachment (MD) (n=14) and macular holes (MH) (n=9),and healthy controls (n=8) were analyzed by enzyme-linked immune sorbent assay (ELISA),sodium dodecyl sulfate gel electrophoresis (SDS-PAGE),Western Blot analysis and circular dichroism (CD) spectroscopy.The data abtained were analyzed by ANOVA.Results The concentration of TTR in the vitreous of healthy controls,macular detachment patients and macular hole patients was 45.2±1.0 mg/L,230.0±16.3 mg/L,109.8±19.0 mg/L,the difference was significant (F=2.69,P＜0.05).The transthyretin extracted from the vitreous of patients with MD showed a much more stable tetrameric structure than transthyretin extracted from the vitreous of patients with MH and the controls.Additionally,ELISA analysis and integrated optical density (IOD) analysis of bands on SDS-PAGE gels revealed that transthyretin concentration in the vitreous of patients with MD was 2.4 times higher than in patients with MH.CD spectroscopy revealed that the secondary structures of transthyretin in the vitreous of MD patients,MH patients and healthy,controls contained 45％,32％ and 5％ α-helix,respectively.Furthermore,the second structures of MD and MH transthyretin were stable at different pH levels (4-11),while that of healthy controls varied at pH levles 4-11.Conclusion Our results suggest that MD and MH patients have higher vitreous concentrations of transthyretin,and more stable secondary structures; additionally,MD TTR has a significantly steady tetrameric structure.These could possibly be due to mutations and misfolding. Key words: Myopia,degenerative; Transthyretin; Retinal holes,macular; Retinal detachment,macular