Abstract
Purpose :
Diabetes Mellitus (DM) is a progressive, chronic disease, with annually increasing mortality rates. Both Type 1 DM (T1DM) and Type 2 DM (T2DM), lack insulin in the body to regulate and maintain blood glucose levels leading to microvascular (retinopathy, neuropathy and nephropathy) and macrovascular (stroke, ischemic heart disease and peripheral vascular disease) complications. DM is known to promote tissue hypoxia. The hypoxic environment can also alter the human corneal function and physiology. Sex hormone receptors have been identified in the human cornea but their role and functions are still unclear, especially in the context of corneal fibrosis. To-date, there are no reports on the role of sex hormones in the hypoxic environment of the diabetic cornea. The aim of this study was to examine hypoxia-induced interplay between sex hormone receptors and fibrosis in corneal DM.
Methods :
Primary human corneal stromal cells isolated from Healthy (HCF), and diabetic (T1DM and T2DM) were cultured for 4 weeks, under normoxic (21% O2) or hypoxic (2% O2) conditions. Utilizing our previously established 3D in vitro model, each cell type was seeded at a density of 1x106 cells/well on transwell inserts in culture medium + stable Vitamin C (0.05 mM). Proteins were isolated and analyzed for the expression of sex hormones receptors: androgen receptor (AR), progesterone receptor (PR) and estrogen receptor beta (ERβ). Fibrotic markers Smooth muscle actin (α-SMA) and Collagen type 3 (Col3), were also examined.
Results :
Our results showed significant upregulation in all three sex hormones receptors (AR, PR, and ERβ) in both T1DM and T2DM under hypoxic conditions as compared to normoxic. Interestingly, hypoxic conditions had no effect on sex hormones receptors in HCFs as compared to normoxic. We observed significant downregulation of α-SMA expression in T1DM but significant upregulation in T2DM under hypoxic conditions. HCF Col3 expression was also significantly upregulated under hypoxic conditions.
Conclusions :
For the first time, we report an intriguing link between the diabetic cornea, sex hormone receptors, and hypoxia. Our data suggests that AR, PR, and ERβ are critical to the downstream, fibrotic effects, seen under corneal hypoxia. Further investigations are necessary in order to fully understand the mechanisms driving hypoxia-induced sex hormone receptor regulations in the diabetic cornea.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.