Numbl inhibits glioma cell migration and invasion by suppressing TRAF5-mediated NF-κB activation

The Notch signaling regulator Numblike (Numbl) is expressed in the brain, but little is known regarding its role in the pathophysiology of glial cells. In this paper, we report that Numbl expression was down-regulated in high-grade human glioma tissue samples and glioblastoma cell lines. To investigate the role of Numbl in glioma migration and invasion, we generated human glioma cell lines in which Numbl was either overexpressed or depleted. Overexpression of Numbl suppressed, while elimination of Numbl promoted, the migration and invasion of glioma cells. Numbl inhibited glioma migration and invasion by dampening NF-κB activity. Furthermore, Numbl interacted directly with tumor necrosis factor receptor-associated factor 5 (TRAF5), which signals upstream and is required for the activation of NF-κB, and committed it to proteasomal degradation by promoting K48-linked polyubiquitination of TRAF5. In conclusion, our data suggest that Numbl negative regulates glioma cell migration and invasion by abrogating TRAF5-induced activation of NF-κB.     

Aucubin suppresses lipopolysaccharide-induced pro-inflammatory responses by blocking the NF-κB translocation signaling pathways in activated microglial cells

Aucubin is an iridoid glycoside with demonstrable hepatoprotective and anti-osteoporotic effects. Herein, using microglial cells and lipopolysaccharide (LPS) to induce inflammatory responses, we studied the signaling pathways involved in the anti-inflammatory action of aucubin and their influence on the expression of several genes known to be involved in inflammation. Aucubin inhibited LPS-stimulated pro-inflammatory responses by suppressing the production of nitric oxide and prostaglandin E₂. Furthermore, aucubin inhibited inducible nitric oxide synthase and cyclooxygenase-2 at both the protein and mRNA levels. In addition, aucubin inhibited pro-inflammatory cytokine production in LPS-stimulated BV-2 microglial cells. Subsequent mechanistic studies revealed that aucubin inhibited the LPS-induced activation of nuclear factor-kappa B (NF-κB) translocation and phosphorylation of phosphatidylinositol 3-kinases (PI3K)/Akt as well as of mitogen-activated protein kinases (MAPKs), which are upstream molecules responsible for controlling inflammatory reactions. These results suggest that aucubin may exert anti-neuroinflammatory responses by suppressing the LPS-induced expression of pro-inflammatory mediators by blocking the activation of NF-κB, PI3K/Akt, and MAPK signaling pathways in microglial cells.     

Schisandra extract ameliorates arthritis pathogenesis by suppressing the NF-κB and MAPK signalling pathways

Schisandra chinensis is a medicinal plant used to treat various diseases. Extracts from the leaves or fruits of S. chinensis and their components are used in osteoarthritis (OA). The OA inhibitory effect of schisandrol A, one of its components, has been previously confirmed. We aimed to confirm the OA inhibitory effect of Schisandra (including components like schisandrol A) to identify why the inhibitory effect of the Schisandra extract is better. First, we investigated the effects of the Schisandra extract on OA as a potential therapeutic. Experimental OA was induced in a mouse model via destabilized medial meniscus surgery. The animals were orally administered the Schisandra extract; the inhibition of cartilage destruction was confirmed using histological analysis. In vitro analysis showed that the Schisandra extract attenuated osteoarthritic cartilage destruction by regulating IL-1β-induced MMP3 and COX-2 levels. The Schisandra extract inhibited IL-1β-induced degradation of IκB (NF-κB pathway) and IL-1β-induced phosphorylation of p38 and JNK (mitogen-activated protein kinase (MAPK) pathway). RNA-sequencing analysis showed that the Schisandra extract decreased the expression of IL-1β-induced MAPK and NF-κB signalling pathway-related genes more than schisandrol A alone. Therefore, Schisandra extract may be more effective than schisandrol A in preventing OA progression by regulating MAPK and NF-κB signalling.     

Jolkinolide B inhibits RANKL-induced osteoclastogenesis by suppressing the activation NF-κB and MAPK signaling pathways

Osteoclasts together with osteoblasts play pivotal roles in bone remodeling. The unique function and ability of osteoclasts to resorb bone makes them critical in both normal bone homeostasis and pathologic bone diseases such as osteoporosis and rheumatoid arthritis. Thus, new compounds that may inhibit osteoclastogenesis and osteoclast function may be of great value in the treatment of osteoclast-related diseases. In the present study, we examined the effect of jolkinolide B (JB), isolated from the root of Euphorbia fischeriana Steud on receptor activator of NF-κB ligand (RANKL)-induced osteoclast formation. We found that JB inhibited RANKL-induced osteoclast differentiation from bone marrow macrophages (BMMs) without cytotoxicity. Furthermore, the expression of osteoclastic marker genes, such as tartrate-resistant acid phosphatase (TRAP), cathepsin K (CtsK), and calcitonin receptor (CTR), was significantly inhibited. JB inhibited RANKL-induced activation of NF-κB by suppressing RANKL-mediated IκBα degradation. Moreover, JB inhibited RANKL-induced phosphorylation of mitogen-activated protein kinases (p38, JNK, and ERK). This study thus identifies JB as an inhibitor of osteoclast formation and provides evidence that JB might be an alternative medicine for preventing and treating osteolysis.     

Artemisinin attenuates lipopolysaccharide-stimulated proinflammatory responses by inhibiting NF-κB pathway in microglia cells

Microglial activation plays an important role in neuroinflammation, which contributes to neuronal damage, and inhibition of microglial activation may have therapeutic benefits that could alleviate the progression of neurodegeneration. Recent studies have indicated that the antimalarial agent artemisinin has the ability to inhibit NF-κB activation. In this study, the inhibitory effects of artemisinin on the production of proinflammatory mediators were investigated in lipopolysaccharide (LPS)-stimulated primary microglia. Our results show that artemisinin significantly inhibited LPS-induced production of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1) and nitric oxide (NO). Artemisinin significantly decreased both the mRNA and the protein levels of these pro-inflammatory cytokines and inducible nitric oxide synthase (iNOS) and increased the protein levels of IκB-α, which forms a cytoplasmic inactive complex with the p65-p50 heterodimeric complex. Artemisinin treatment significantly inhibited basal and LPS-induced migration of BV-2 microglia. Electrophoretic mobility shift assays revealed increased NF-κB binding activity in LPS-stimulated primary microglia, and this increase could be prevented by artemisinin. The inhibitory effects of artemisinin on LPS-stimulated microglia were blocked after IκB-α was silenced with IκB-α siRNA. Our results suggest that artemisinin is able to inhibit neuroinflammation by interfering with NF-κB signaling. The data provide direct evidence of the potential application of artemisinin for the treatment of neuroinflammatory diseases.     

Autophagy in the intestinal epithelium reduces endotoxin-induced inflammatory responses by inhibiting NF-κB activation

Autophagy is a lysosomal degradation pathway that is essential for survival, differentiation, development and homeostasis. There is growing evidence that impaired autophagy leads to the pathogenesis of diverse diseases. However, the role of autophagy in intestinal epithelium is not clearly understood, although previous studies have pointed out the possibility for the relationships of autophagy with bowel inflammation. In this study, we investigated the involvement of autophagy in intestinal epithelium with inflammatory responses. We generated the mice with a conditional deletion of Atg7, which is one of the autophagy regulated gene, in intestinal epithelium. In Atg7-deficient small intestinal epithelium, LPS-induced production of TNF-α and IL-1β mRNA was enhanced in comparison to the control small intestinal tissues. In addition, the degree of LPS-induced activation of NF-κB was promoted in Atg7-deficient intestinal epithelium. These results demonstrate that autophagy can attenuate endotoxin-induced inflammatory responses in intestinal epithelium resulting in the maintenance of intestinal homeostasis.     

NF-κB activation in myeloid cells mediates ventilator-induced lung injury

Background

Although use of the mechanical ventilator is a life-saving intervention, excessive tidal volumes will activate NF-κB in the lung with subsequent induction of lung edema formation, neutrophil infiltration and proinflammatory cytokine/chemokine release. The roles of NF-κB and IL-6 in ventilator-induced lung injury (VILI) remain widely debated.

Methods

To study the molecular mechanisms of the pathogenesis of VILI, mice with a deletion of IкB kinase in the myeloid cells (IKKβ^△mye), IL-6^-/- to WT chimeric mice, and C57BL/6 mice (WT) were placed on a ventilator for 6 hr.WT mice were also given an IL-6-blocking antibody to examine the role of IL-6 in VILI.

Results

Our results revealed that high tidal volume ventilation induced pulmonary capillary permeability, neutrophil sequestration, macrophage drifting as well as increased protein in bronchoalveolar lavage fluid (BALF). IL-6 production and IL-1β, CXCR2, and MIP2 expression were also increased in WT lungs but not in those pretreated with IL-6-blocking antibodies. Further, ventilator-induced protein concentrations and total cells in BALF, as well as lung permeability, were all significantly decreased in IKKβ^△mye mice as well as in IL6^-/- to WT chimeric mice.

Conclusion

Given that IKKβ^△mye mice demonstrated a significant decrease in ventilator-induced IL-6 production, we conclude that NF-κB–IL-6 signaling pathways induce inflammation, contributing to VILI, and IкB kinase in the myeloid cells mediates ventilator-induced IL-6 production, inflammation, and lung injury.     

Molecular activation of NF-κB, pro-inflammatory mediators, and signal pathways in γ-irradiated mice

The effects of γ-irradiation on inflammatory gene expression, including NF-κB activation, in the kidney of C57/BL6 mice exposed to 1–9 Gy doses of ⁶⁰Co γ-irradiation. Radiation enhanced the NF-κB activation and oxidative stress caused a dose-dependent disruption in the redox balance. The significance of this study is the new molecular information gained on γ-irradiation effects through the activation of pro-inflammatory genes by NF-κB via the MAPK signaling pathway. Considering the exquisite sensitivity of NF-κB and other pro-inflammatory mediators to the redox status, we conclude that the activation of inflammatory processes by irradiation is likely initiated by increased oxidative stress.     

Differential usage of NF-κB activating signals by IL-1β and TNF-α in pancreatic beta cells

The cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α induce β-cell death in type 1 diabetes via NF-κB activation. IL-1β induces a more marked NF-κB activation than TNF-α, with higher expression of genes involved in β-cell dysfunction and death. We show here a differential usage of the IKK complex by IL-1β and TNF-α in β-cells. While TNF-α uses IKK complexes containing both IKKα and IKKβ, IL-1β induces complexes with IKKα only; this effect is achieved by induction of IKKβ degradation via the proteasome. Both IKKγ and activation of the TRAF6-TAK1-JNK pathway are involved in IL-1β-induced IKKβ degradation.