[Pathogenetic role of multifunctional protein alpha-2-macroglobulin and its activity in tears and serum in age-related macular degeneration and proliferative diabetic retinopathy].

Unlabelled: Alpha-2-macroglobulin (-MG) is a multifunctional protein involved in neurodegeneration, inflammation and neovascularization, which are key processes in the pathogenesis of age-related macular degeneration (AMD) and proliferative diabetic retinopathy (PDR). AMD and PDR are two of the main causes of vision loss and blindness, are difficult to treat, and are generally diagnosed at the stage of irreversible changes.

Purpose: This study estimates the activity of -MG in the blood serum and tears of patients with AMD and PDR in order to reveal the relation of its levels with the intensity of the pathological process in the retina.

Material And Methods: The study included 17 patients (34 eyes) with AMD, 15 patients (30 eyes) with PDR, and 15 healthy adults (30 eyes) of the similar age. The activity of -MG in serum and tears was measured enzymatically using the specific substrate N-benzoyl-DL-arginine-p-nitroanilide (BAPNA).

Results: The activity of -MG in tears of patients with AMD was on the average 3.5 times higher than in healthy controls, and in patients with PDR - 1.5 times higher. Patients with AMD at the submacular fibrosis stage showed decreased -MG activity in tears. The activity of -MG in serum of patients with AMD and PDR was on the average 25% higher than in healthy persons. No correlation was revealed between serum and tear levels of -MG activity.

Conclusion: This study revealed for the first time that in AMD and PDR the activity of -MG in tears is increased, and that in AMD the increase is higher than in PDR. An increase of -MG activity in serum confirms the presence of systemic inflammation. Absence of correlation between the serum and tear activity of -MG confirms its local origin. The high level of -MG activity in tears reflects the presence of an active destructive process in the retina, justifying its further investigation as a predictor of AMD and PDR course, as well as an indicator of therapy effectiveness.