Protection of glucotoxicity by a tripeptide derivative of α-melanocyte-stimulating hormone in human epidermal keratinocytes

Background: Chronic skin ulcers are a major complication and a therapeutic challenge in patients with diabetes mellitus. Glucose-induced accumulation of reactive oxygen species (ROS) is considered to be an important pathogenetic factor in diabetes. Objectives: To characterize the impact of high glucose (HG) on normal human keratinocytes (NHKs) and examine if Lys-d-Pro-Thr (KdPT), a tripeptide derived from α-melanocyte-stimulating-hormone, has protective effects. Methods: We investigated the key functions of NHKs under HG conditions with or without KdPT in vitro as well as ex vivo employing a skin organ culture model. Results: HG impaired metabolic activity, cell proliferation, viability and migration of NHKs. As shown by atomic force microscopy HG altered the biophysical properties of NHKs, i.e. cell size and elasticity. Glucotoxicity in NHKs was paralleled by the induction of intracellular ROS and endoplasmic reticulum stress. KdPT attenuated HG-induced oxidative stress and antagonized the effects of glucose on cell viability, metabolic activity and migration. Importantly, KdPT also antagonized the suppressive effect of HG on epidermal migration in wounded human skin organ cultures. Conclusions: Our findings highlight a novel effect of KdPT that could be exploited for the future therapy of diabetic skin ulcers.