Abstract
Purpose :
Diabetic retinopathy, classified as a vasculopathy, is recognized as a neurovascular complication of diabetes. The retinal neurodegeneration is considered the primary manifestation that precedes any microvascular alteration. In addition, Müller cells are the most significant producer of VEGF in the pre-hypoxic retina that might exacerbate retinal damage. Thus, the present study was aimed to explore the pathways/ markers that potentiate VEGF production and degeneration of Müller cells in hyperglycemic condition.
Methods :
MIO-M1 human Müller cells were treated with either 5.5 mM glucose (euglycemic) or 30 mM glucose (hyperglycemic) for 24 hours. Subsequently, cells were processed for RNA isolation and gene expression of 451 genes across 10 pathways (immunological and oxidative stress) were done on a medium-throughput digital quantification platform by NanoString (NanoString Technologies Inc., Seattle, WA, USA). 100 ng of total RNA was used as an input for this analysis. Statistical analysis, pathway scoring and differential expression were computed by the nCounter advanced analysis 2.0 nSolver software.
Results :
Hyperglycemia altered key mediators of autophagy, cytokine and chemokine signaling, hypoxia, reactive oxygen response, KEAP1/NRF2 and TLR signaling. Hyperglycemia led to significant (p<0.05) over-expression of several hypoxic genes, including HIF1A and VEGFA. Hyperglycemia also lead to immunosuppression with simultaneous downregulation of several reactive oxygen defense genes, including GPX4 and SOD1. In addition, the transcriptomic profiling across these pathway identified several genes that were significantly (p<0.05) altered, of which the top genes from each pathway were HERC1, HIF1A, GNG12, VEGFA, NQO1, HRAS1, NFKB2, SLC7A11, MAP2K1, RPS6KA1.
Conclusions :
Hyperglycemia alters critical immunological, oxidative stress and angiogenic markers in Müller cells in as early as 24 hour time point. The immunosuppressive status seems conducive for angiogenesis marked by increased VEGFA expression, and explains the role of Müller cells in producing maximum VEGF even in pre-hypoxic retina. The immunosuppressive status and simultaneous oxidative stress seems to potentiate angiogenesis and neurodegeneration in early diabetic retina. The transcriptomic analysis provides key insights, and the markers identified might be of diagnostic, prognostic and therapeutic significance.
This is a 2020 ARVO Annual Meeting abstract.