Abstract
Purpose :
Diabetes mellitus (DM) and elevated Intraocular pressure are risk factors for glaucoma, however the mechanisms of this association has not been investigated. The purpose of this study is to understand the alteration in gene expression response in human trabecular meshwork (HTM) cells to hyperglycemic conditions.
Methods :
Cultured HTM cells from three donor eyes were maintained in 1% fetal bovine serum (FBS) glucose-free Dulbecco’s Modified Eagle Medium (DMEM) with glucose concentrations of 5.5 mM (physiologic serum glucose) or 30 mM (DM patients) for 5 days followed by RNA collection, cDNA conversion and qPCR. Statistical analysis was done via student’s t-test where results were statistically significant if p<0.05 for the sample size n=3. We particularly examined the gene expression involved in tissue fibrosis including extracellular matrix (ECM), endothelial mesenchymal transition (EndMT) and genes involved in lipid biosynthesis.
Results :
Hyperglycemic conditions showed a significant decrease in the cholesterol biosynthetic enzymes 3-hydroxy-3-methyl-glutaryl-coenzyme A synthase (HMGCS) and reductase (HMGCR) (p=0.04) and its regulatory transcription factor Sterol regulatory element-binding protein - SREBP 1 and 2. Interestingly there was an increasing trend in - a) profibrotic genes - Collagen 1A, alpha smooth muscle actin, transforming growth factor beta 2 (TGFB2), and Serpin Family E Member 1 (SERPINE), b) extracellular matrix (ECM) components - Fibronectin (FN), Tenascin C (TNC), Collagen 4 alpha (COL4A), Collagen 6 alpha (COL6A), and Elastin (ELN), and c) transcription factors involved in EndMT associated with fibrosis - Snail family transcriptional repressor 1 (SNAIL), Snail family transcriptional repressor 2 (SLUG), and Twist-related protein 1 (TWIST1).
Conclusions :
Our preliminary data reveals a negative relationship between cholesterol biosynthesis machinery and positive correlation to fibrotic phenotype in TM as a response to elevated glucose levels. Interestingly, increased ECM deposition in the TM outflow pathway is known to increase resistance to aqueous humor outflow and elevate IOP. Therefore we predict that EndMT resulting in TM fibrosis could be a potential mechanism of IOP elevation in DM subjects.
This is a 2021 ARVO Annual Meeting abstract.