Altered serum levels of autophagy proteins Beclin-1 and mTOR in patients with exudative age-related macular degeneration.

Autophagy is a key process in the maintenance of cellular survival and homeostasis. Inhibition of autophagy results in degenerative changes resembling ageing. We wondered if autophagy can contribute to the pathogenesis of age-related macular degeneration (AMD). We aimed to investigate the serum concentrations of two key autophagy regulators, Beclin-1 and mechanistic target of rapamycin (mTOR), in patients with exudative AMD. This retrospective case-control study included 38 patients with exudative AMD and 36 sex- and age-matched controls selected among senile cataract patients. Circulating Beclin-1 and mTOR were assessed using an enzyme-linked immunosorbent assay. The proteins levels were correlated with age, sex, duration of ocular symptoms, as well as angiographic and optical coherence tomography findings. Serum Beclin-1 levels were much lower in patients with AMD than in controls (median, 0.100 ng/ml versus 1.123 ng/ml; p = 0.0033), while mTOR levels did not differ (median, 4.377 ng/ml versus 3.608 ng/ml; p = 0.4522). Participants of the study older than 70 years had lower Beclin-1 levels than younger ones (p = 0.0444). However, this difference was the most evident in patients with AMD (p = 0.0024). Serum mTOR levels increased with age. In patients with AMD, lower mTOR levels were associated with drusen, while higher levels were observed in those with a fibrous scar in the contralateral eye (p = 0.0212). Our findings suggest that circulating Beclin-1 decreases with age and that is downregulated in patients with AMD.

Non-responsiveness and tachyphylaxis to anti-vascular endothelial growth factor treatment in naive patients with exudative age-related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of central visual loss in people aged over 50 years in well developed countries. Although the anti-vascular endothelial growth factor (VEGF) therapy has become a standard treatment for exudative AMD, its effectiveness may be limited in some cases. We aimed to assess the prevalence of non-responsiveness and tachyphylaxis to anti-VEGF drugs in patients with exudative AMD. The study included 63 initially treatment-naive AMD patients who were analyzed for non-responsiveness and tachyphylaxis to intravitreal injections (IVI) of ranibizumab and aflibercept. The participants were enrolled in a National Healthcare Fund (NHF) Therapeutic Program for the Treatment of Exudative AMD. Best-corrected visual acuity (BCVA) and morphological features of a disease activity assessed in optical coherence tomography (OCT) were evaluated during a 12-month follow-up. The percentage of non-responders achieved 22.2% (14 eyes). No significant correlation was found between the type of VEGF inhibitor and a negative response to therapy. Eight patients (12.7%) developed early tachyphylaxis, which was more common in eyes treated with aflibercept (P = 0.04). The presence of serous pigment epithelium detachment (sPED) at baseline was associated with non-responsiveness as determined by both BCVA (OR 18.2, 95% CI 2.86 - 248; P = 0.021) and OCT features (OR 23.0, 95% CI 1.80 - 321; P = 0.030). Eyes treated with aflibercept showed statistically significant greater BCVA improvement (P = 0.0034) and central retinal thickness (CRT) reduction (P = 0.0129) as compared to ranibizumab group during a loading phase of therapy. In a maintain phase of treatment the differences in BCVA and CRT between these two groups were not statistically significant, however eyes treated with aflibercept still showed better functional and anatomical results. Anti-VEGF therapy is an effective method of treatment for exudative AMD, however some patients may show week or no positive reaction or may develop tachyphylaxis. Awareness of these possible negative effects is an important clinical problem in the long-term management of AMD patients with VEGF inhibitors.