Purpose
Patients with diabetes mellitus (DM) are at an increased risk for developing corneal complications and delayed wound healing. This study was to investigate the expression profiles of homeostatic, healing corneal epithelial cells (CECs) derived from non-diabetic (DL) and DM rats and identify pathways leading to delayed epithelia l wound healing in DM corneas.
Methods
Male Sprague-Dawley rats were induced into type I DM with an intraperitoneal injection of 55 mg/kg of streptozotocin (STZ). CECs were removed from DM and age-matched DL rats (homeostatic CECs) and wound healing was allowed for 40 h; CECs migrated into the wound bed were collected (healing CECs). Four groups, each containing 3 samples, were subjected to affymetrix GeneChip® Rat Genome 230 2.0 Array analysis. The ANOVA analysis for the RMA normalized data sets was done by the commercial microarray data analysis software Partek Genomic Suite. Signaling pathway and functional network analyses were performed using Genomatrix Pathways System software.
Results
Following normalization of raw data from three biological replicates, 5426 probes were altered at least in one paired comparison. When healing CECs were compared to homeostatic CECs (2.0 fold cut off), a total of 3216 probes were differentially expressed (1636 increase and 1580 decrease) in DL corneas, 3504 probes were differentially expressed (1978 increase and 1526 decrease) in DM CECs; 2497 probes with altered expression in both DL and DM CECs. When DM CECs were compared to DL CECs (1.5 fold cutoff), there were 774 (397 increase and 377 decrease) in homeostatic CECs and 1889 probes (636 increase and 1253 decrease) in healing CECs; 350 probes were differentially expressed in both homeostatic and healing CECs of DM corneas. The expression patterns more than20 genes were verified by real-time PCR and/or immunehistochemistry. In DM versus DL comparison, NF-κB, cannabinoid receptor, and HMGB1/RAGE are altered signaling pathways. In healing versus homeostatic comparison, major pathways altered are cell adhesion, cytoskeleton and ECM remodeling, and TGFβ-Wnt signaling.
Conclusions
These novel gene expression signatures provide new insights and clues into the mechanisms underlying epithelial wound healing and new therapeutic targets for accelerating delayed epithelial wound healing such as that observed in diabetic corneas and/or skin.
Keywords: 482 cornea: epithelium •
498 diabetes •
535 gene microarray