Conclusion: Our study uncovers key roles for IL-17 and TNF-α as mediators of liver inflammation and activation of hepatic stellate cells in
NLRP3 inflammasome activated myeloid cells. These findings may lead to novel therapeutic strategies aimed at halting the progression of liver injury and fibrogenesis. Protease Inhibitor Library Disclosures: The following people have nothing to disclose: Alexander Wree, Matthew D. McGeough, Maria E. Inzaugarat, Carla A. Pena, Alejandra Chernavsky, Hal M. Hoffman, Ariel E. Feldstein Liver ischemia and reperfusion (I/R) injury can be a detrimental consequence encountered during major liver resection, transplant, massive trauma and hypovolemic shock. The initiation of liver sterile inflammation results in the release of damage associated molecular patterns (DAMPs) such as HMGB1 and histones, in addition to the rapid recruitment of neutrophils to the site of injury. Neutrophil infiltration and accumulation in the ischemic liver lobe after reperfusion contributes to the damage observed during liver I/R injury.
Upon activation, neutrophils have been shown to release fibers composed of chromatin and protein to form neutrophil extracellular p38 MAPK pathway traps (NETs). Whether NETs participate in liver I/R and the subsequent consequences remain unknown. Therefore, the purpose of our work is to elucidate whether NETs are formed during liver I/R and their role. In vitro, treatment of neutrophils isolated from the femur of mice with media from hypoxic hepatocytes, HMGB1 or histones resulted in significant NET formation by immunofluorescence. This was inhibited by adding peptidylarginine deiminases (PAD) 4 (a nucleoprotein that mediates NET formation by citrullinating histones) inhibitor or DNase1 to either inhibit or disrupt NET formation, Farnesyltransferase respectively. In vivo, mice were subjected to a non-lethal partial (70%) warm liver I/R model. We found abundant NET formation in ischemic liver lobes after I/R as evidenced by confocal immunofluorescence, increased
citrullinated histone in the liver tissue, and increased levels of serum free DNA and nucleosomes. Treatment with either PAD4 inhibitor or DNAse conferred significant protection compared to controls after liver I/R evidenced by decreased AST and ALT levels, significantly less hepatic necrosis by histology, and decreased levels of circulating inflammatory cytokines, free DNA, and nucleosomes. In summary, our study reveals that NETs are formed during liver I/R and subsequently increase the injury. Targeting NET formation may be a new therapeutic strategy to reduce ischemia-related liver damage. Disclosures: The following people have nothing to disclose: Samer Tohme, Hai Huang, Allan Tsung Expansion of the visceral adipose tissue (VAT) volume can lead to the hypoxic death of adipocytes.