Specific PKC βII inhibitor: one stone two birds in the treatment of diabetic foot ulcers.

Sushant Kumar Das,Yi Feng Yuan,Mao Quan Li

doi:10.1042/bsr20171459

Sushant Kumar Das, Yi Feng Yuan + Show 1 more

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https://doi.org/10.1042/bsr20171459

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Abstract

To explore whether or not inhibition of protein kinase C βII (PKC βII) stimulates angiogenesis as well as prevents excessive NETosis in diabetics thus accelerating wound healing. Streptozotocin (STZ, 60 mg/kg/day for 5 days, i.p.) was injected to induce type I diabetes in male ICR mice. Mice were treated with ruboxistaurin (30 mg/kg/day, orally) for 14 consecutive days. Wound closure was evaluated by wound area and number of CD31-stained capillaries. Peripheral blood flow cytometry was done to evaluate number of circulating endothelial progenitor cells (EPCs). NETosis assay and wound tissue immunofluorescence imaging were done to evaluate the percentage of neutrophils undergoing NETosis. Furthermore, the expression of PKC βII, protein kinase B (Akt), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), and histone citrullation (H3Cit) were determined in the wound by Western blot analysis. Ruboxistaurin accelerated wound closure and stimulated angiogenesis in diabetic mice. The number of circulating EPCs was increased significantly in ruboxistaurin-treated diabetic mice. Moreover, ruboxistaurin treatment significantly decreases the percentages of H3Cit+ cells in both peripheral blood and wound areas. This prevented excess activated neutrophils forming an extracellular trap (NETs) formation. The expressions of phospho-Akt (p-Akt), phospho-eNOS (p-eNOS), and VEGF increased significantly in diabetic mice on ruboxistaurin treatment. The expressions of PKC βII and H3Cit+, on the other hand, decreased with ruboxistaurin treatment. The results of the present study suggest that ruboxistaurin by inhibiting PKC βII activation, reverses EPCs dysfunction as well as prevents exaggerated NETs formation in a diabetic mouse model; thereby accelerating the wound healing process.

Highlights

Diabetic foot ulcers (DFUs) are a major end-stage complication of diabetes mellitus (DM)
The present study found that diabetic mice had higher level of PKC protein kinase C βII (βII) in wound tissue when compared with normal glycemia controlled mice
Recent studies have shown that protein kinase C βII (PKC βII) activation decreases the PI3-kinase/protein kinase B (Akt)-dependent endothelial nitric oxide synthase (eNOS) activation in response to vascular endothelial growth factor (VEGF) or insulin stimulation [8,9]. eNOS is one of the major players in mobilizing endothelial progenitor cell (EPC) into circulation initiating the angiogenesis process

Summary

Introduction

Diabetic foot ulcers (DFUs) are a major end-stage complication of diabetes mellitus (DM) It is characterized by impaired wound healing resulting in considerable morbidity and mortality [1]. It is believed that foot ulcers in diabetic patients are difficult to heal due to low grade chronic infection of the wound bed This low chronic inflammation has been suggested to be brought on by several factors such as neuropathy, improper oxygenation, insufficient vascular supply to extremities, and bacterial infections [2]. It is recognized that activated neutrophils form an extracellular trap (NET) by releasing granules of protein and chromatin to form extracellular fiber to bind and kill bacteria This process is followed by a type of cell death (NETosis) from the release of nuclear materials within NETs c 2018 The Author(s).

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