Effects of Brimonidine on Retinal Pigment Epithelial Cells and Müller Cells Exposed to Amyloid-Beta 1–42 Peptide In Vitro

Abstract

BACKGROUND AND OBJECTIVE: To evaluate whether brimonidine can prevent cytotoxicity in human retinal pigment epithelial (RPE) and Müller (MIO) cells after exposure to amyloid-beta 1–42 (Aβ42). MATERIALS AND METHODS: An in vitro model of geographic atrophy (GA), which is an end-stage complication of age-related macular degeneration (AMD), simulated with the application of Aβ42 in cell culture. RPE and MIO cells were pretreated with brimonidine for 6 hours, then exposed to 10μM Aβ42 for 24 hours. Several concentrations (one time [1×], two times [2×], and five times [5×]) of brimonidine were used to assess for a dose-related effect. Assays were immediately run following the treatment period. 2′,7′-Dichlorofluorescein diacetate was used to assess reactive oxygen species production, the MTT assay was used to assess cell viability, and the JC-1 dye assay was used to assess mitochondrial membrane potential. The main outcome measures were reactive oxygen species (ROS) production, cell viability, and mitochondrial membrane potential (ΔΨm) of RPE and MIO cells following the treatment phase. RESULTS: High-dose (5×) brimonidine was capable of reducing ROS production in RPE and MIO cells with exposure to Aβ42. The application of Aβ42 alone did not trigger a rise in ROS production. Brimonidine was unable to rescue cell viability and ΔΨm after exposure to Aβ42 in both cell cultures. Instead, high-dose (5×) brimonidine appeared to increase the toxicity to cell viability and ΔΨm in cultures exposed to Aβ42. However, this was not due to medication toxicity alone, because high-dose (5×) brimonidine without exposure to Aβ42 did not affect the cell viability in both cell types. CONCLUSION: Brimonidine may have a role in preventing oxidative cellular injury in AMD. However, this role does not appear to translate into protection against some of the cytotoxic effects observed from this in vitro model of GA. In this cellular model of GA, brimonidine is able to reduce oxidative stress but is unable to rescue cell viability or prevent mitochondrial dysfunction. [ Ophthalmic Surg Lasers Imaging Retina . 2018;49:S23–S28.]

Role of amyloid β-peptide in the pathogenesis of age-related macular degeneration

“…32 Several medical agents, such as Brimonidine, Puerarin and Baicalin, have been shown to alleviate intracellular pyroptosis and viability damage through preventing Aβ-induced oxidative stress damage and inflammatory activity. [33][34][35] Also, sirtuin 1 (SIRT1) has been identified as a protective factor, which suppresses the activation of NF-κB signalling pathway induced by Aβ in AMD. 36 These results have shown the proinflammatory role of Aβ in AMD.…”

Self-Assembled Multilayer Films for Time-Controlled Ocular Drug Delivery

“…Upon comparison of the cell viability of the self-assembled films with and without Brim with untreated cells, it is clear that extracts of the films do not show any cytotoxicity. In fact, it is clear that there is a metabolic stimulation of the cells, which can be attributed to the presence of Brim , which has been described to have a protective role in preventing oxidative stress of retinal pigment epithelial (RPE) and Müller cells, , thus contributing to its increased viability. It has also been shown that polymers from the family of poly­(β-amino esters) can promote cell viability, as shown in HEK293 cells …”

An Update to Biomechanical and Biochemical Principles of Retinal Injury in Child Abuse

“…Based on these studies, accumulation of Aβ1-42 in retinal cells can result in activation of PARP1 and subsequent repression of sirtuin 1 (SIRT1), ultimately leading to increased expression of caspase-3 and caspase-9, hence accelerated apoptosis [67]. The deleterious effects of amyloid aggregates are not restricted to epithelial pigment cells, as these complexes can also negatively affect Muller cells or retinal gliocytes, which are involved in neuroprotection and immunity [68].…”