Involvement of serum anti-retinal antibodies in the pathophysiology of diabetic retinopathy: a pilot study

The aim of this single-center cross-sectional study was to identify tissue targets for circulating anti-retinal antibodies (ARAs) in the serum of patients with diabetic retinopathy (DR). The study included 61 participants with DR (30 with nonproliferative diabetic retinopathy and 31 with proliferative diabetic retinopathy) and 30 healthy controls. An indirect immunofluorescence (IIF) test was used to detect serum ARAs and identify their targets in the tissue. Four types of ARAs were found in serum samples from DR patients: antibodies against the outer segments of the rods, antibodies against the outer segments of the cones, antibodies against the cytoplasmic components of retinal nuclear layer cells, and antibodies against retinal nerve fibers. A significant difference was noted between groups in the prevalence of antibodies against the outer segments of the rods (NPDR, 40%; PDR, 74.2%; and controls, 40%; P = 0.008) as well as antibodies against the outer segments of the cones (NPDR, 23.3%; PDR, 61.3%; and controls, 30%; P = 0.005). Interestingly, the distribution of immunofluorescence intensity for the outer segments of the rods and cones differed significantly between study groups (P ≢ 0.001 and P = 0.019, respectively). In conclusion, the results of our pilot study showed that in most patients with DR, the outer segments of photoreceptors tend to be the tissue target for serum ARAs. This may indicate their possible involvement in the pathogenesis of DR. However, further research is needed to fully elucidate whether these antibodies participate in photoreceptor damage in the course of DR.