Receptor Interacting Protein 3-Mediated Necroptosis Promotes Lipopolysaccharide-Induced Inflammation and Acute Respiratory Distress Syndrome in Mice

Abstract

Necrosis amplifies inflammation and plays important roles in acute respiratory distress syndrome (ARDS). Necroptosis is a newly identified programmed necrosis that is mediated by receptor interacting protein 3 (RIP3). However, the potential involvement and impact of necroptosis in lipopolysaccharide (LPS)-induced ARDS remains unknown. We therefore explored the role and mechanism of RIP3-mediated necroptosis in LPS-induced ARDS. Mice were instilled with increasing doses of LPS intratracheally to induce different degrees of ARDS. Lung tissues were harvested for histological and TUNEL staining and western blot for RIP3, p-RIP3, X-linked inhibitor of apoptosis protein (XIAP), mixed lineage kinase domain-like protein (MLKL), total and cleaved caspases-3/8. Then, wild-type and RIP3 knock-out mice were induced ARDS with 30 mg/kg LPS. Pulmonary cellular necrosis was labeled by the propidium Iodide (PI) staining. Levels of TNF-a, Interleukin (IL)-1β, IL-6, IL-1α, IL-10 and HMGB1, tissue myeloperoxidase (MPO) activity, neutrophil counts and total protein concentration were measured. Results showed that in high dose LPS (30mg/kg and 40mg/kg) -induced severe ARDS, RIP3 protein was increased significantly, accompanied by increases of p-RIP3 and MLKL, while in low dose LPS (10mg/kg and 20mg/kg) -induced mild ARDS, apoptosis was remarkably increased. In LPS-induced severe ARDS, RIP3 knock-out alleviated the hypothermia symptom, increased survival rate and ameliorated the lung tissue injury RIP3 depletion also attenuated LPS-induced increase in IL-1α/β, IL-6 and HMGB1 release, decreased tissue MPO activity, and reduced neutrophil influx and total protein concentration in BALF in severe ARDS. Further, RIP3 depletion reduced the necrotic cells in the lung and decreased the expression of MLKL, but had no impact on cleaved caspase-3 in LPS-induced ARDS. It is concluded that RIP3-mediated necroptosis is a major mechanism of enhanced inflammation and lung tissue injury in high dose LPS- induced severe ARDS in mice.

Necroptosis in the Pathophysiology of Disease

“…with oleic acid (model of acute respiratory distress syndrome). In a similar study, Wang et al 39 induced acute respiratory distress syndrome via intratracheal lipopolysaccharide in both Ripk3 þ/þ and Ripk3 À/À mice. This group found that Ripk3 À/À mice had a reduction in hypothermia, increased survival, and reductions in cytokines and neutrophils within the lung parenchyma.…”

Lipopolysaccharide from Crypt-Specific Core Microbiota Modulates the Colonic Epithelial Proliferation-to-Differentiation Balance

“…Indeed, the deletion of RIPK3 improved the survival rate of colonic crypt cultures during stimulation with LPSs purified from CSCM members. Interestingly, it was recently shown that lung injury observed upon high-dose-LPS-induced acute respiratory distress syndrome in mice was due to RIPK3-mediated necroptosis ( 46 ). This could be linked to a study showing that sepsis affects quiescent muscle stem cells, causing a defect in muscle regeneration by inducing increased apoptosis of satellite cells ( 47 ).…”

Bifidobacterium animalis ssp. Lactis 420 Mitigates Autoimmune Hepatitis Through Regulating Intestinal Barrier and Liver Immune Cells

“…The dysregulation of RIP3 signaling is considered a crucial event inducing inflammation through necroptosis ( 30 ). Previous studies have already shown that LPS induced programmed cell death and thereby increased the expressions of its target genes, such as RIP3 and MLKL ( 77 , 78 ). Recent studies demonstrated that some harmful pathogen also activated RIP3 signaling pathway including Staphylococcus aureus , Chlamydia muridarum and influenza H7N9 virus ( 79 – 81 ).…”