Objective: To identify the correlation between serum-based differentially expressed proteins and pathological myopia.
Methods: It was a case-control study. The serum of 30 pathological myopia patients and 30 age- and gender-matched normal controls were collected from Shanghai First People's Hospital affiliated to Shanghai Jiaotong University. These patients were divided into 4 groups including macular-off retinal detachment (8 cases), retinal geographic atrophy (5 cases), macular hole (11 cases) and choroidal neovascular (6 cases). The serum specimens of normal controls were used as immunogen to immune rabbits in order to prepare polyclonal antibodies. Purified by Protein A cartridge, these mixed antibodies were then combined with CNBr-activated Sepharose so as to synthesize affinity medium which was finally used to treat the serum specimens. According to the theory of antigen and antibody, common background proteins would be deleted. The remaining non-binding proteins were analyzed by capillary high-performance liquid chromatography and LTQ-MASS. Nonparametric statistical analysis was used to detect the correlation each differentially expressed protein.
Results: The result of HPLC and LTQ-MASS in 30 specimens of patients revealed 4 peaks of differentially expressed proteins including JTR (positive in 18 specimens, 60%), HP( positive in 11 specimens, 36.7%), HPX (positive in 10 specimens, 33.3%), APO (positive in 8 specimens, 26.7%). There were positive correlations between these 4 proteins (the correlation between TTR and HP, HPX, APO is r = 0.480, 0.577, 0.492; the correlation between HP and TTR, HPX, APO is r = 0.480, 0.783, 0.636; the correlation between HPX and TTR, HP, APO is r = 0.577, 0.783, 0.853; the correlation between APO and TTR, HP, HPX is r = 0.492, 0.636, 0.853; P < 0.05). In group of macular hole, TTR was positive expressed in 7 specimens while other differential proteins were low expression. In group of choroidal neovascular, TTR and HP were positive expressed in 6 specimens while HPX was significantly high in 5 specimens. In other two groups, the expression of 4 differential proteins was rather low.
Conclusions: Screening molecular biomarkers by serum-based proteomics can efficiently exclude common proteins and find differential proteins correlated with pathological myopia. These differential proteins may become molecular biomarkers of pathological myopia in the future.