GnRH impairs diabetic wound healing through enhanced NETosis

Sung Un Kang,Young Uk Park,Myung-Hoon Lee,Chul-Ho Kim,Chang-Hak Han,Haeng-Jun Kim,Yun Sang Lee,Ho-Ryun Won

doi:10.1038/s41423-019-0252-y

Sung Un Kang, Young Uk Park + Show 6 more

Open Access

https://doi.org/10.1038/s41423-019-0252-y

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Abstract

It has been reported that neutrophil extracellular traps (NETs) impair wound healing in diabetes and that inhibiting NET generation (NETosis) improves wound healing in diabetic mice. Gonadotropin-releasing hormone (GnRH) agonists are associated with a greater risk of diabetes. However, the role of GnRH in diabetic wound healing is unclear. We determined whether GnRH-promoted NETosis and induced more severe and delayed diabetic wound healing. A mouse model of diabetes was established using five injections with streptozotocin. Mice with blood glucose levels >250 mg/dL were then used in the experiments. GnRH agonist treatment induced delayed wound healing and increased NETosis at the skin wounds of diabetic mice. In contrast, GnRH antagonist treatment inhibited GnRH agonist-induced delayed wound healing. The expression of NETosis markers PAD4 and citrullinated histone H3 were increased in the GnRH-treated diabetic skin wounds in diabetic mice and patients. In vitro experiments also showed that neutrophils expressed a GnRH receptor and that GnRH agonist treatment increased NETosis markers and promoted phorbol myristate acetate (PMA)-induced NETosis in mouse and human neutrophils. Furthermore, GnRH antagonist treatment suppressed the expression of NETosis markers and PMA-induced NETosis, which were increased by GnRH treatment. These results indicated that GnRH-promoted NETosis and that increased NETosis induced delayed wound healing in diabetic skin wounds. Thus, inhibition of GnRH might be a novel treatment of diabetic foot ulcers.

Highlights

Diabetes affects ~170 million people worldwide, and the number of patients is expected to double by 2030.1 Diabetic foot ulcers (DFUs) are a major morbidity occurring in 15% of diabetic patients.[2]
The Gonadotropin-releasing hormone (GnRH) agonist increased NETosis in the mouse model of diabetic wound healing Previous studies have reported that diabetes primes neutrophils to undergo NETosis and that NETosis is involved in impaired wound healing during diabetes.[9]
We determined whether GnRH treatment induced neutrophils to undergo NETosis in the wounds of diabetic mice

Summary

Introduction

Diabetes affects ~170 million people worldwide, and the number of patients is expected to double by 2030.1 Diabetic foot ulcers (DFUs) are a major morbidity occurring in 15% of diabetic patients.[2] Wound healing complications in diabetic patients are complex and mediated by many factors, including impaired angiogenesis,[3,4] decreased growth factor production,[5,6] reduced cell migration and proliferation,[7] and uncontrolled expression of metalloproteinases (MMPs).[8,9] Because of the complicated mechanisms involved in DFUs, treatments are not effective, and FDA-approved therapies for DFUs are not routinely used even though protocols for standard care are available. Studies have reported on the formation of neutrophil extracellular traps (NETs), which appear as web-like structures; NET generation (NETosis) is known as a unique type of cell death of neutrophils and is involved in the pathogenesis of impaired wound healing in diabetic patients.[10] We have previously reported that high glucose levels accelerate phorbol myristate acetate (PMA)-mediated NETosis. We reported that levels of the PAD4 protein, which is one of the marker for NETosis, were enhanced in neutrophils of diabetic patients and that DNase treatment for digesting NETs improved diabetic wound healing

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