Hyperglycaemic conditions hamper keratinocyte locomotion via sequential inhibition of distinct pathways: new insights on poor wound closure in patients with diabetes

Abstract

BACKGROUND: Diabetes mellitus (DM) is characterized by impaired insulin signalling, elevated plasma glucose, and predisposition towards complications involving several organs. A major complication of DM is impairment of wound healing. In the re-epithelialization process during wound healing, migration of keratinocytes is a crucial step. Our previous report demonstrated that keratinocytes cultured in hyperglycaemic media showed decreased cell mobility. OBJECTIVES: The current study aimed to explore the effects of high glucose on keratinocyte migration after different treatment durations. METHODS: Keratinocytes were cultivated for indicated time periods under various concentrations of glucose. Relevant assays including Transwell migration and in vitro wound scratch assays, flow cytometric analysis, matrix metalloproteinase-1 (MMP-1) activity assay, determination of mRNA expression and Western blotting were performed. RESULTS: We demonstrated that (i) keratinocyte motility progressively and significantly decreased; (ii) the keratinocyte activation marker K16 was significantly suppressed; (iii) expression of alpha2beta1 integrin and MMP-1, both crucial for keratinocyte locomotion on collagen type I, was significantly downregulated; and (iv) expression of the phosphorylated signal transducer and activator of transcription-1 significantly decreased after hyperglycaemic treatment. More specifically, different pathways become involved after prolonged duration of high glucose cultivation to reduce keratinocyte locomotion further. CONCLUSIONS: We have demonstrated that high glucose treatment results in progressive suppression of keratinocyte locomotion and elucidated the molecular mechanisms involved. These results provide a reasonable explanation for the poor wound healing seen in patients with DM.