Prevalence of anti-retinal autoantibodies in different stages of Age-related macular degeneration

Abstract

Background: Age-related macular degeneration (AMD) is the leading cause of central vision loss in older adults. Anti-retinal autoantibodies (AAbs) have been found in individuals with AMD. The goal of the study was to determine the AAb specificity in different stages of AMD, and determine whether there is a prevalent AAb signature.

Methods: Sera of 134 participants in the Age-related Eye Disease Study were analyzed for anti-retinal AAbs by western blotting. The subjects were classified by diagnostic subgroups based upon their clinical classification: No AMD, Intermediate AMD, and Late AMD - geographic atrophy (GA) and Late AMD - neovascular (NV).

Results: The presence of anti-retinal AAb was detected in 58% patients with Intermediate and Late AMD, and 54% of those with no AMD. AAbs bound to fifteen different retinal antigens. Most individuals had 1 specific AAbs (67%), with the remainder having 2 to 4 different AAbs. Over 40% of patients with Intermediate AMD, and 46% of those with GA had anti-enolase AAbs, compared with 29% of individuals with NV and 29% with no AMD. Different AAbs signatures related to NV as compared to GA and/or Intermediate AMD were distinguished. Anti-40-kDa (10%) and 42-kDa (16%) autoantibodies were associated with Intermediate AMD, while anti-30-kDa AAbs (23%) were primarily present in GA. Anti-32-kDa (12%), 35-kDa (21%), and 60-kDa (8%) AAbs were more frequent in NV AMD.

Conclusions: A unique AAb pattern for each of the disease subgroups was present when AMD progressed from the intermediate to the late forms of severity. Differences in the frequency of specific AAbs between AMD subgroups suggested that they may participate in pathogenicity of AMD. Further studies are necessary to confirm these observations in the larger cohort and individual AMD patients over time.

Figure 1

Fundus photographs illustrating subgroups of AREDS patients in the study. (A) No AMD; (B). Intermediate AMD showing large drusen in the macula; (C) Late AMD - geographic atrophy; (D) Late AMD - neovascular AMD; (E) late AMD – both geographic atrophy and neovascular AMD. Stars indicate the affected areas.

Figure 2

Incidence of anti-retinal autoantibodies in patients with AMD and age-matched unaffected control subjects. (A) Seropositive total subjects with AMD divided into the AMD subgroups and controls, and in (B) Seropositive females and males with AMD and controls. Groups: control group (no AMD), intermediate AMD, late AMD – geographic atrophy (GA), late AMD – neovascular (NV) AMD.

Figure 3

Anti-retinal autoantibodies in different stages of AMD. Distribution of anti-retinal autoantibodies against 15 different retinal proteins identified by molecular weight in the 4 study groups of patients: control group (no AMD), intermediate AMD, late AMD - geographic atrophy, and late AMD - neovascular AMD. Bars show the percent of positive AAbs for each antigen; arrows point at unique antigens for each AMD group.

Figure 4

Trends in AAbs associations between intermediate and late AMD. Five anti-retinal AAbs designated by their target antigen molecular weight (30-kDa, 35-kDa, 40-kDa, 42-kDa, and 68-kDa) have a tendency to decrease in advance stages of AMD (anti-40-kDa, anti-42-kDa, and anti-68-kDa) as others to increase (anti-30-kDa and anti-35-kDa) that could potentially be used as disease biomarkers.

Figure 5

Relationship of anti-retinal autoantibodies in different stages of AMD with smoking and arthritis. (A) Prevalence of anti-retinal autoantibodies in men and women who never smoked, are current smokers, or who stopped smoking in AMD and control subjects. High anti-retinal seropositivity is observed in never smoking females that dropped 2 folds in ever smoker female patients. In contrast, smoking or discontinuation of smoking is associated with an increased frequency of AAbs in men regardless of the stage of disease. Never = never smoking female/male; Current = currently smoking female/male; Ever = former smoking female/male. (B) Differences in anti-retinal autoantibody association in female and male with AMD and arthritis and compared to the age-matched unaffected controls. Bars represent a percent of seropositive subjects in each subgroup. Note that female with intermediate AMD had 4 times more AAbs than men, in contrast men with late AMD-NV had 2 times higher frequency of anti-retinal antibodies. Horizontal lines show statistical significance between groups, p < 0.05 (One-way analysis of variance, Bonferroni’s multiple comparison test).