Alpha-1 Antitrypsin Decreases NFkB Signaling in Müller Cells in an in Vitro Diabetic Retinopathy Model.

Abstract

Purpose : Diabetic retinopathy is a leading cause of blindness in working-age population and is regarded as a microvascular complication due to the breakdown of the endothelial barrier. Müller cells maintain the homeostasis of the retinal extracellular milieu and contribute to several processes involved in diabetic retinopathy, like neuronal dysfunction, the set-up of a chronic inflammatory retinal environment, the production of pro-angiogenic factors leading to neovascularization, and eventually cell death. In a previous work, we demonstrated that Alpha-1 Antitrypsin (A1AT), diminished TNF-a expression in Müller cells, but molecular mechanisms involved remained unknown. In this work, we explore the expression of proteins involved in AKT and NFkB pathway in Müller cells exposed to high glycemia.

Methods : Mouse retinas were obtained from freshly enucleated eyes incubated with collagenase I and trypsin. Retinas were disaggregated and incubated with DMEM for 5 days to allow the enrichment of Müller cells population. Müller cells obtained were incubated 24hours with DMEM 30mM glucose (Control), DMEM 30mM glucose + 4.5mg/ml A1AT (Control + A1AT), DMEM 100mM glucose (Diabetic), DMEM 100mM glucose + 4.5mg/ml A1AT (Diabetic + A1AT). Cells were harvested with RIPA buffer for Western blot assay or fixed for immunohistochemistry.

Results : AKT levels are decreased with the presence of A1AT. NFkB p65 and NFkB p52 were diminished with A1AT treatment, while IkBa was increased.

Conclusions : Outcomes support the hypothesis that A1AT reduces TNF-a expression through decreasing AKT/NFkB signaling. These results help to understand mechanisms involved in inflammatory processes in diabetic retinopathy and make A1AT a suitable molecule for the treatment of diabetic retinopathy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.