Analysis of aqueous humour proteins of eyes with and without pseudoexfoliation syndrome

Abstract

Pseudoexfoliation syndrome (PEX) has been suggested to represent a blood-aqueous barrier impairment leading to a higher protein content in aqueous humour of eyes with PEX. However, the nature of a prospective PEX protein has not yet been described. We set out to re-evaluate protein content and examine protein composition for prospective PEX protein candidates in aqueous humour of eyes with PEX syndrome. Aqueous humour of 52 patients with PEX and 38 without PEX signs was sampled during cataract or glaucoma surgery. Total aqueous protein concentration in the samples was analysed in 43 PEX specimens and 32 non-PEX specimens according to Bradford. Aqueous protein composition of all samples was determined by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS PAGE) and silver staining. Screening for amyloids was performed in nine PEX samples and six non-PEX samples by Congo Red staining and polarised light microscopy. Aqueous protein concentration was not significantly increased in PEX eyes in comparison with non-PEX eyes. Furthermore, we could not detect any characteristic difference in protein band sizes of the two groups after SDS PAGE. However, we were able to show the presence of amyloid exclusively in aqueous humour of PEX patients. Conclusion: our results do not confirm a generally higher protein concentration in pseudoexfoliation syndrome eyes. This does not necessarily contradict a blood-aqueous barrier impairment but illustrates the variance in protein concentration between and within the two groups. No characteristic protein band allocatable to pseudoexfoliation syndrome proteins could be detected in any of the samples. However, our findings support the theory that the pseudoexfoliation syndrome is associated with an amyloid of a serum protein.