FBXO6 regulates the antiviral immune responses via mediating alveolar macrophages survival.

Inducing early apoptosis in alveolar macrophages is one of the strategies influenza A virus (IAV) evolved to subvert host immunity. Correspondingly, the host mitochondrial protein nucleotide-binding oligomerization domain-like receptor (NLR)X1 is reported to interact with virus polymerase basic protein 1-frame 2 (PB1-F2) accessory protein to counteract virus-induced apoptosis. Herein, we report that one of the F-box proteins, FBXO6, promotes proteasomal degradation of NLRX1, and thus facilitates IAV-induced alveolar macrophages apoptosis and modulates both macrophage survival and type I interferon (IFN) signaling. We observed that FBXO6-deficient mice infected with IAV exhibited decreased pulmonary viral replication, alleviated inflammatory-associated pulmonary dysfunction, and less mortality. Analysis of the lungs of IAV-infected mice revealed markedly reduced leukocyte recruitment but enhanced production of type I IFN in Fbxo6-/- mice. Furthermore, increased type I IFN production and decreased viral replication were recapitulated in FBXO6 knockdown macrophages and associated with reduced apoptosis. Through gain- and loss-of-function studies, we found lung resident macrophages but not bone marrow-derived macrophages play a key role in the differences FBXO6 signaling pathway brings in the antiviral immune response. In further investigation, we identified that FBXO6 interacted with and promoted the proteasomal degradation of NLRX1. Together, our results demonstrate that FBXO6 negatively regulates immunity against IAV infection by enhancing the degradation of NLRX1 and thus impairs the survival of alveolar macrophages and antiviral immunity of the host.

Yangonin treats inflammatory osteoporosis by inhibiting the secretion of inflammatory factors and RANKL expression.

OBJECTIVES: As the main cause of osteoporosis, abnormal activity of osteoclasts could disrupt the balance between bone resorption and formation. Moreover, up-regulation of nuclear factor-kappa ligand (RANKL) expression by chronic inflammation-mediated inflammatory factors might contribute to the differentiation of osteoclast precursor cells. Therefore, an anti-inflammatory agent named yangonin was presented for inhibiting osteoclast and relieving inflammatory osteoporosis through down-regulating inflammatory factors. METHODS: We established a model of macrophage inflammation and then verified the anti-inflammatory effect of yangonin. The inhibitory effect of yangonin on osteoclasts was detected by tartrate-resistant acid phosphatase (TRAP) staining, Western blotting and quantitative real-time PCR (qRT-PCR). Finally, micro-CT, TRAP and hematoxylin-eosin (HE) staining were used to show the effect of yangonin on inflammatory osteoporosis in vivo. RESULTS: Our results suggested that yangonin was able to reduce the secretion of inflammatory factors, down-regulate osteoclast-related genes such as TRAP, RANKL, cathepsin K (CTSK) and nuclear factor-activated T-cell 1 (NFATc1). Furthermore, it was demonstrated that yangonin could suppress the function of inflammatory cytokines in osteoclast differentiation and reporting, wherein NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways were involved. In an in vivo study, we implied that yangonin has a relieving effect on inflammatory osteoporosis. CONCLUSION: Our research shows that yangonin down-regulates inflammatory factors and inhibits the bone-breaking effect of inflammation through NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways to achieve the purpose of treating inflammatory osteoporosis.

Pulsatilla saponin E suppresses viability, migration, invasion and promotes apoptosis of NSCLC cells through negatively regulating Akt/FASN pathway via inhibition of flotillin-2 in lipid raft.

PURPOSE: Pulsatilla saponins from pulsatilla chinensis (Bunge) Regel have potential anti-tumor activities to certain human cancers. However, the roles of pulsatilla saponin E separated from pulsatilla saponins in non-small cell lung cancer (NSCLC) have not been reported. MATERIALS AND METHODS: After treating NSCLC cells by pulsatilla saponin E at different concentrations, cell viability was measured by MTT and CCK-8 assays, and cell migration, invasion and apoptosis were detected by scratch wound-healing, transwell and flow cytometry assays. The contents of free cholesterol (FC) and total cholesterol (TC) were measured by high performance liquid chromatography (HPLC). The expression levels of flotillin-1, flotillin-2, Akt, fatty acid synthase (FASN) were detected by qRT-PCR and Western blot assays. RESULTS: Pulsatilla saponin E suppressed viability, migration, invasion and promoted apoptosis of NSCLC cells followed by regulation of apoptosis-related proteins, reduced contents of FC and TC, and the expression levels of flotillin-1, flotillin-2, Akt, and FASN in a concentration-dependent manner. However, the inhibitory effects of pulsatilla saponin E on viability, migration, invasion of A549 cells and the expression levels of flotillin-1, flotillin-2, Akt, and FASN were reversed by flotillin-2 overexpression. CONCLUSIONS: Our study revealed that pulsatilla saponin E suppressed migration, invasion and promoted apoptosis of NSCLC cells through negatively regulating Akt/FASN signaling pathway via the inhibition of flotillin-2 in lipid raft (LR). The current findings could be explored for developing a novel therapeutic drug for NSCLC treatment.

MitoQ protects against hyperpermeability of endothelium barrier in acute lung injury via a Nrf2-dependent mechanism.

Recently, numerous evidence has revealed that excessive reactive oxygen species (ROS) production and mitochondrial disruption during acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS) will aggravate the inflammatory process. To identify whether antioxidation can be one of the treatment strategies during this progress, we chose mitoQ, a mitochondria-targeted antioxidant that was proved to be effective in reducing ROS generated in mitochondria, as a ROS scavenger to investigate the role of antioxidation in ALI. We demonstrated that overoxidation occurred during the process of ALI, which could be reduced by mitoQ. In the meantime, apoptosis of endothelial cells of ALI mice, accompanied by hyperpermeability of pulmonary vascular and impaired pulmonary function, was partially reversed following an intraperitoneal injection of mitoQ. Moreover, in in vitro study, lipopolysaccharides (LPS) induced excessive ROS production, mitochondrial dysfunction and apoptosis in human pulmonary microvascular endothelial cells (HPMECs), which were rectified by mitoQ. To explore underlying mechanisms, we proceeded RNA-sequencing and found significantly upregulated expression of musculoaponeurotic fibrosarcoma F (MafF) in mitoQ treated group. Additionally, mitoQ inhibited the degradation and increased nuclear translocation of NF-E2-related factor 2 (Nrf2) and upregulated its downstream antioxidant response elements (AREs), such as heme oxygenase (HO)-1 and NAD(P)H:quinone oxidoreductase (NQO)-1. This effect was abolished by transfecting HPMECs with Nrf2 or Maff siRNA. In Nrf2 deficient mice, the protective effects of mitoQ on LPS model of ALI were largely vanished. Taken together, these results provide insights into how antioxidation exerts beneficial effects on ALI via maintaining mitochondrial hemostasis, inhibiting endothelial cells apoptosis, attenuating the endothelial disruption and regulating lung inflammation via Nrf2-MafF/ARE pathway.