Abstract
Purpose :
The Lamina Cribrosa (LC) is a key site of retinal ganglion cell axonal injury in Open Angle Glaucoma (OAG). Our lab has previously shown human glaucoma LC cells have pro-fibrotic altered gene expression and mitochondrial dysfunction. Metformin has been shown to have anti-fibrotic effects in numerous organ systems. In this study, we aim to assess Metformin’s effect on mitochondrial function in glaucomatous LC cells by carrying out a systematic mitochondrial bioenergetic assessment.
Methods :
Human LC cells from age matched normal and confirmed glaucoma donors were assessed using a Seahorse XFe96 Analyzer. Glaucoma LC cells were treated with Metformin at different doses: 10mM, 5mM, 2mM, 1mM, 0.5mM, 0.1mM and 0.05mM. Adenosine Triphosphate (ATP) production, Basal Oxygen Consumption Rate (OCR), Maximal OCR and Spare Respiratory Capacity were measured and normalized to total protein content using the Bradford method. In addition, the effect of Metformin on extracellular matrix (ECM) gene expression (Col1A1, a-SMA, and vitronectin) was assessed by real time RT-PCR.
Results :
Glaucoma LC cells have lower basal and maximal OCR, lower spare respiratory capacity and lower ATP production than the normal cells. Treatment with Metformin, however, significantly improves Maximal OCR (0.473 ± 0.026 pmol/min vs 0.398 ± 0.083 pmol/min) (p <0.05) and spare respiratory capacity (0.193 ± 0.035 pmol/min vs 0.168 ± 0.046 pmol/min) (p <0.05) in glaucoma cells,. Additionally, there is a trend towards improvement of basal OCR and ATP production in treated glaucoma LC cells versus untreated glaucoma LC cells (p=0.1076 and p=0.0655 respectively). The most effective Metformin dose was 0.1 mM. In addition, Metformin treatment (0.1mM) resulted in a significant (p <0.05) reduction of the ECM gene expression seen in glaucoma LC cells.
Conclusions :
We demonstrate evidence of mitochondrial dysfunction and enhanced ECM gene expression in glaucoma LC cells and subsequent improvement with Metformin treatment. These results may provide some explanation as to the reduced OAG glaucoma incidence in those taking Metformin. A better understanding of Metformin’s effect on mitochondrial dysfunction and fibrosis may aid the development of a disease modifying agent in OAG.
This is a 2021 ARVO Annual Meeting abstract.