Understanding Epithelial-Mesenchymal Transition in Diabetic Wounds

Background: Peripheral neuropathy, a common complication in diabetic patients, increases their risk to injury and has a significant impact on our society. An altered cytokines and growth factors landscape has been attributed to wound healing impairment in people living with diabetes; however, a direct mechanistic role of the neurological condition to wound closure is less understood.

Methods: In this study, using a combination of laser capture microdissection and microarray analysis of keratinocytes at the epithelial tongues from diabetic and normal mice, we observed an enrichment of genes involved in neurotransmitter acetylcholine (ACh) metabolism, suggesting a non-neuronal role for ACh.

Results: Indeed, we detected lower levels of ACh in the wound fluids of diabetic mice than in wild-type mice. Acetylcholine induces an epithelial-mesenchymal like transition, such as increased cell migration and cell spreading in primary human keratinocytes as revealed by live cell imaging. This observation was further confirmed by the upregulation of mesenchymal markers and concomitant downregulation of epithelial markers using qPCR and immunoblot analysis. Keratinocytes cultured in high glucose (25 mM) condition showed an attenuated response to ACh compared with cells in low glucose (5 mM) environment. Taken together, our findings reveal that ACh can trigger EMT-like changes in keratinocyte. The combination of low ACh in wound fluids and hyperglycemic wound microenvironment severely dampened the critical EMT process in wound keratinocytes, culminating in delayed reepithelialisation.

Conclusions: Given that many aspects of wound repair are widely conserved in other organs, our findings will be relevant to other tissues as well, and will provide an important foundation to improve wound repair in a variety of patients.