Pristimerin alleviates cigarette smoke-induced inflammation in chronic obstructive pulmonary disease via inhibiting NF-κB pathway.

Cigarette smoke (CS) is a risk factor for chronic obstructive pulmonary disease (COPD), which can exacerbate inflammation and oxidative stress. Pristimerin (Pris) is a natural compound with antioxidant and anti-inflammatory effects. We managed to evaluate the protective effects of Pris on CS-induced COPD. The CS-induced COPD mice model and cell model were constructed. The effects of Pris treatment on lung function, inflammatory cell infiltration, myeloperoxidase (MPO), and pathological changes of lung tissues in mice model were evaluated. The impacts of Pris treatment on inflammatory factors, chemokines, and oxidative stress parameters in mice lung tissues and cells were determined by kits. The viability of human bronchial epithelial cells after Pris treatment was tested by CCK-8. The activation of NF-κB pathway was confirmed by Western blot and immunofluorescence. CS treatment impaired lung function, reduced weight of mice, and enhanced inflammatory cell infiltration, MPO, and lung tissue damage, but these effects of CS were reversed by Pris treatment. Furthermore, Pris treatment downregulated the levels of malondialdehyde, IL-6, IL-1ß, TNF-α, CXCL1, and CXLC2, but upregulated superoxide dismutase and catalase levels. Pris treatment could overturn CS-induced activation of the NF-κB pathway. Pris alleviates CS-induced COPD by inactivating NF-κB pathway.

Salt-inducible kinases inhibitor HG-9-91-01 targets RIPK3 kinase activity to alleviate necroptosis-mediated inflammatory injury.

Receptor-interacting protein kinase 3 (RIPK3) functions as a central regulator of necroptosis, mediating signaling transduction to activate pseudokinase mixed lineage kinase domain-like protein (MLKL) phosphorylation. Increasing evidences show that RIPK3 contributes to the pathologies of inflammatory diseases including multiple sclerosis, infection and colitis. Here, we identified a novel small molecular compound Salt-inducible Kinases (SIKs) inhibitor HG-9-91-01 inhibiting necroptosis by targeting RIPK3 kinase activity. We found that SIKs inhibitor HG-9-91-01 could block TNF- or Toll-like receptors (TLRs)-mediated necroptosis independent of SIKs. We revealed that HG-9-91-01 dramatically decreased cellular activation of RIPK3 and MLKL. Meanwhile, HG-9-91-01 inhibited the association of RIPK3 with MLKL and oligomerization of downstream MLKL. Interestingly, we found that HG-9-91-01 also trigger RIPK3-RIPK1-caspase 1-caspase 8-dependent apoptosis, which activated cleavage of GSDME leading to its dependent pyroptosis. Mechanistic studies revealed that SIKs inhibitor HG-9-91-01 directly inhibited RIPK3 kinase activity to block necroptosis and interacted with RIPK3 and recruited RIPK1 to activate caspases leading to cleave GSDME. Importantly, mice pretreated with HG-9-91-01 showed resistance to TNF-induced systemic inflammatory response syndrome. Consistently, HG-9-91-01 treatment protected mice against Staphylococcus aureus-mediated lung damage through targeting RIPK3 kinase activity. Overall, our results revealed that SIKs inhibitor HG-9-91-01 is a novel inhibitor of RIPK3 kinase and a potential therapeutic target for the treatment of necroptosis-mediated inflammatory diseases.