Hyperglycemia primes NETosis, which exacerbates ischemic brain damage
Abstract Background:Hyperglycemia is common and associated with poor outcomes in acute ischemic stroke patients. It is not well understood how hyperglycemia exacerbates brain damage in ischemic stroke. Neutrophil extracellular traps (NETs) have shown an emerging role in noninfectious diseases. We aimed to determine the role of NETs in acute ischemic stroke with hyperglycemia. Methods: NETs were immunostained using NET markers (citrullinated histone H3 (H3Cit)) and quantified in thrombi retrieved from ischemic stroke patients undergoing endovascular treatment. BKS-db/db and wild-type mice were used to establish the permanent middle cerebral artery occlusion (pMCAO) model. Wild-type mice were injected with glucose to simulate acute hyperglycemia after middle cerebral artery occlusion. NETs were detected in the peri-ischemic brain tissue. After inhibition of NET formation, infarction volume, neurological function and inflammatory factors in pMCAO mice were evaluated. Results: H3Cit, a marker of NETs, was observed in almost all thrombi. H3Cit was much more abundant in thrombi from diagnosed diabetic patients and acute hyperglycemic patients compared with those in normglycemic patients. In pMCAO mice, NETs were induced by chronic diabetes and acute hyperglycemia. Inhibition of NET formation with the peptidylarginine deiminase 4 (PAD4) inhibitor Cl-amidine decreased the infarction volume both in db/db and wild-type mice with hyperglycemia. Neurological function deficits were alleviated by blocking NET formation, as shown in the grip strength and rotarod tests. The levels of TNF-α and IL-1β but not IL-6 coincided with NET formation. Conclusions: Hyperglycemia may exacerbate brain damage in ischemic stroke through NETs. The underlying mechanisms deserve to be further studied.