Hydrogen sulfide primes diabetic wound to close through inhibition of NETosis.

Diabetes-induced neutrophil NETosis impairs wound healing through neutrophil extracellular traps (NETs). Reactive oxygen species (ROS)-triggered activation of mitogen-activated protein kinase (MAPK) ERK1/2 and p38 is involved in NETosis. Hydrogen sulfide (HS), an endogenous signaling molecule, accelerates diabetic wound healing (DWH), and inhibits ROS production, ERK1/2 and p38 activation, while its level is decreased in diabetes. However, it remains unknown whether HS could accelerate DWH through inhibition of NETosis, and whether this inhibitory effect was associated with blockage of ROS-induced ERK1/2 and p38 activation. In order to solve these problems, serum NETs content was measured in diabetic foot patients and healthy individuals. Wound was created in dorsal skin of LepR and control mice and NETs content in wound tissues was tested. An in vitro NETosis model was induced by phorbol 12-myristate 13-acetate (PMA) in isolated neutrophils. Effects of HS in form of NaS on skin wound healing and NETosis were investigated both in vivo and in vitro. It was found that NETs level was highly increased in diabetic foot patients. Comparing with LepR mice, DWH was delayed in LepR mice, accompanied with high NETs level. In PMA-induced NETosis model, peptidylarginine deiminase (PAD)-4 and citrullinated histone H, as well as NETs components dsDNA framework, myeloperoxidase and neutrophil elastase, were significantly increased. PMA-induced neutrophil NETosis and NETs formation were abolished by treatment with HS. The delayed DWH of diabetic mice was partially restored by intraperitoneal injection of HS, meanwhile, the highly expressed NETosis and NETs release were also down-regulated. The treatment with HS not only attenuated ROS production but also abolished MAPK ERK1/2 and p38 activation. Like the effects of HS, inhibition of MAPK ERK1/2 or p38 could decrease NETs release. These findings suggests that HS attenuates NETosis and primes diabetic wound to heal through blockage of ROS-mediated MAPK ERK1/2 and p38 activation.