Abstract
Purpose: :
Glaucomatous patients exhibit increased titers of serum antibodies to a variety of retina and optic nerve proteins. This study aimed to comparatively determine the immunoreactivity of glaucomatous patient serum and aqueous humor samples against human retinal proteins obtained from glaucomatous versus non-glaucomatous donors.
Methods: :
ELISA titers of IgG and IgM antibodies reacting to glaucomatous or control retinal proteins were measured in serum and aqueous humor samples collected from 22 patients with glaucoma and 18 age-matched control subjects without glaucoma. To determine intraocular antibody production, Goldman-Witmer and albumin coefficients were calculated. In addition, 1D- and 2D-western blot analysis were performed to test the immunoreactivity of patient sera against human retinal proteins obtained from glaucomatous and non-glaucomatous donors. Protein spots on sister gels corresponding to detected immunoreactivities were analyzed by LC-MS/MS.
Results: :
Titers of serum antibodies reacting to retinal proteins were greater in glaucomatous samples relative to controls (p<0.001). Similar to serum samples, glaucomatous aqueous humor samples also exhibited higher antibody titers than non-glaucomatous controls, while in approximately 50% of patients with glaucoma, the aqueous humor antibody titers exceeded the serum antibody titers. In addition, the titers of glaucomatous serum antibodies reacting to glaucomatous human retinal proteins were greater than the titers of serum antibodies reacting to retinal proteins obtained from non-glaucomatous donors (p<0.01). Proteomic analysis revealed complex profiles of serum and aqueous humor antibodies reacting with a diverse set of retinal proteins, which included stress proteins, structural proteins, and glycolytic enzymes.
Conclusions: :
Higher titers of aqueous humor antibodies than serum antibodies support local immunoglobulin production. Differential immunoreactivity against glaucomatous versus non-glaucomatous retinal proteins also support that risk factors present in glaucomatous tissues facilitate increased autoantibody production in glaucoma and contribute to failure in the regulation of immune activity.Continuing studies should clarify whether increased antibodies in glaucoma merely represent an injury response process for immune system-driven removal of cell debris or also play a pathogenic role in the progression of neurodegeneration.
Keywords: immunomodulation/immunoregulation • proteomics • neuroprotection