Abstract
Purpose :
Diabetes Mellitus (DM) is a group of metabolic disorders that can cause structural and functional changes in the human cornea, including nerve and stromal defects. Monocarboxylate transporters (MCTs) are a family of proton-linked plasma membrane transporters that carry monocarboxylates (i.e. molecules with one carboxylate group) across plasma membranes. In the context of corneal health and disease, their role, presence, and functions are undetermined and solely focused on the most common MCT isoforms 1 through 4. The aim of this study is to investigate the role of MCTs 1 through -5, -8, and -10, in the context of corneal diabetes.
Methods :
Primary stromal corneal fibroblasts were isolated from Healthy (HCFs), as well as Type I (T1DMs), and Type II (T2DMs) diabetic subjects. Mono-cultures: Cells were cultured for three weeks on 6-well transwell plates and stimulated with stable Vitamin C, to promote ECM assembly. Co-cultures: SH-SY5Y neurons were seeded at a density of 12k and 500k on top of the 3D stromal constructs after three weeks, to create the stroma-neuron co-culture, followed by an additional week in culture. Cultures without neurons served as controls. At four-weeks, all constructs were processed for RNA isolation and Real-Time Quantitative Reverse Transcription PCR (qRT- PCR). Furthermore, expression of MCTs was also investigated, using immunofluorescence.
Results :
No significant modulation of MCTs was observed for any of the cell types tested at the low cell density of 12k. Co-cultures with 500k neuron cell densities showed upregulation of MCT1, MCT8 and MCT10 in HCFs, T1DMs and T2DMs. The cells were stained with different MCT isoforms for immunofluorescence. Data showed bright red signal within the cytoplasm, indicating the presence of MCTs, but no obvious changes between conditions.
Conclusions :
By utilizing two 3D in vitro models, this study reveals the existence and modulation of MCTs in the diabetic cornea. The changes observed, due to neuronal density, suggest that MCTs are potentially critical to neuronal degeneration and pathology seen in diabetic keratopathy/neuropathy. Further studies are needed, in order to fully delineate the role of MCTs in corneal diabetes.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.