651 NLRP3 Activation Induced by Neutrophil Extracellular Traps Sustains Inflammatory Response in the Diabetic Wound

Abstract Introduction Persistent inflammatory response in the diabetic wound impairs the healing process, resulting in significant morbidity and mortality. Mounting evidence indicates that the activation of NLRP3 inflammasome in macrophages (MF) contributes to the sustained inflammatory response and impaired wound healing associated with diabetes. However, the main trigger of NLRP3 inflammasome in the wounds is not known. Neutrophils, as sentinels of the innate immune system and key stimulators of MF, are immune cells that play the main role in the early phase of healing. Neutrophils release extracellular traps (NETs) as defense against pathogens. On the other hand, NETs induce tissue damage. NETs have been detected in the diabetic wound and implicated in the impaired healing process, but the mechanism of NETs suspend wound healing are elusive. Methods WB, immunofluorescence and immunocoprecipitation were used to detect the expression of NETs, NLRP3 inflammasome and IL-1b in diabetic foot ulcer wounds and the expression and activation of NLRP3 inflammsome after lowering the level of NETs. The role of NETs in activating macrophage inflammsome was verified and its mechanism was explored. Induced type I diabetic rats by STZ injection to detect the expression of NETs in the wound and observe the effects of exogenous DNase I on the expression of inflammasome and IL-1b in the wound, inflammatory cell infiltration and wound healing. Results NLRP3 and NETs are elevated in human and rat diabetic wounds. NETs overproduced in the diabetic wounds triggered NLRP3 inflammasome activation and IL-1b release. NETs up-regulated NLRP3 and pro-IL-1b levels via the TLR-4/TLR-9/NF-kB signalling pathway. NETs elicited ROS, which facilitated the association between NLRP3 and TXNIP, and activated the NLRP3 inflammasome. DNase I alleviated the activation of NLRP3 inflammasome, regulated the immune cell infiltration, and accelerated wound healing. Conclusions NETs contribute to the activation of NLRP3 inflammasome and sustained inflammatory response in the diabetic wound. NET digestion by DNase I alleviated the activation of NLRP3 inflammasome and accelerated wound healing. Applicability of Research to Practice