NF-κB P65 In Cells Research Articles

456-P: HMGB1 Inhibition Protects Schwann Cells from High Glucose–Induced Cytotoxicity

Objective: Damage to Schwann cells play a crucial role in diabetic peripheral neuropathy (DPN) . To observe whether HMGB1 inhibitor (Glycyrrhizic acid, GA) can prevent diabetic Schwann cells damage and its potential mechanisms. Methods: RSC96 cells were divided into 5 groups: NG group (5.6 mmol/L) and HG group (25.0 mmol/L) , HG+GA (1μM) group, HG+GA (10μM) , HG+GA (100μM) . Small interfering RNA was used to knock out HMGB1. CCK8 assay was used to detect the proliferation of RSC96 cells. The levels of inflammatory factors were determined by ELISA. The mRNA expression of NGF and neuritin-1 was detected by qRT-PCR. The expression levels of NSE, cleaved-caspase-3, RAGE, p38MAPK, ERK, JNK and NF-κBp65 in cells were measured by western blot. Results: GA at the concentration of μM for 24h had significant inhibitory effect on HMGB1 synthesis and secretion (P<0.05) . Schwann cell viability in high glucose was restored due to GA and siHMGB1 (P<0.05) . GA intervention and siHMGB1 potently prevented inflammatory substance generation (TNF-α, IL-1β, IL-6, MCP-1 and ICAM-1) , alleviated the neurotrophic factor reduction (NGF and neuritin-1) , and suppressed cellular apoptosis related protein activation (cleaved caspase-3) in Schwann cells exposed to high glucose ambience (P<0.05) . Moreover, we found that RAGE expression, p38MAPK phosphorylation and nuclear NF-κBp65 expression in high glucose-stimulated Schwann cells was reversed by GA or siRNA interference with HMGB1 (P<0.05) . Conclusions: GA and siHMGB1 can not only inhibit HMGB1 expression in Schwann cells exposed to high glucose, but also enhance cell viability. GA and siHMGB1 restored neurotrophic factors level and reduce cleaved caspase-3 expression in Schwann cell due to its anti-inflammatory ability, which may be related to the inhibition of RAGE/p38MAPK/nuclear NF-κBp65 pathway. HMGB1 may implicate in Schwann cells lesion in high glucose milieu and HMGB1 inhibition protects Schwann cells from high glucose induced cytotoxicity. Funding National Natural Science Foundation of China Grant Award (81700723)

Ellagic acid attenuates streptozocin induced diabetic nephropathy via the regulation of oxidative stress and inflammatory signaling

Diabetic nephropathy (DN) is the leading cause of chronic renal disease. Accumulating evidence suggested that oxidative stress and inflammatory processes are involved in the development of DN. In the present study, the DN model was established by injecting mice with STZ (180 mg*kg-1) intraperitoneally, and treated with EA (50, 100 and 150 mg*kg-1) and IRB (positive control) once daily by intragastric gavage. At the same time, rat kidney NRK-52E cells were cultured and incubated with EA and TAK-242 (inhibitor of TLR4) respectively before stimulating with LPS. The mental conditions, body weight, blood glucose, serum albumin (Alb), serum TNF-α, renal function, anti-oxidative enzymes, and protein expression of TLR4, IRAK4, TRAF6, IKKβ, NF-κb P65, HMGB1 in renal tissue were determined. Meanwhile, the proteins expression of TLR4, IRAK1 and NF-κBp65 in cells were further analyzed. The results showed that EA could improve the daily state and body weight; decrease the blood glucose, levels of TNF-α and serum creatinine; elevate the activities of antioxidant enzymes; ameliorate the renal pathology; inhibit the up regulation of expression of proteins TLR4, IRAK4, TRAF6, IKK-β, NF-κBp65 and HMGB1 in DN mice. These results suggested that EA ameliorated STZinduced oxidative renal injury by the inhibition of HMGB1-TLR4-NF-кB pathway.

Piperlongumine decreases cell proliferation and the expression of cell cycle-associated proteins by inhibiting Akt pathway in human lung cancer cells

Piperlongumine (PL) is an alkaloid of a pepper plant found in Southeast Asia. PL is known to induce selective toxicity towards a variety of cancer cell types. To explore the possible anti-lung cancer effects of PL, A549 cells were treated with PL (0–40 μM) for 24 h. Alterations in the expression of cell cycle-associated proteins (cyclin D1, cyclin-dependent kinase 4 (CDK4), CDK6 and retinoblastoma (Rb)) and intracellular signaling molecules (extracellular signal receptor-activated kinase 1/2 (ERK1/2), Akt, p38 and nuclear factor-κB (NF-κB)) were examined in cells following treatment of PL using Western blot analysis. Results showed that proliferation of cells were significantly decreased by PL in a dose-dependent manner. Flow cytometry results demonstrated increased number of cells in G1 phase in PL (40 μM)-treated group. Reactive oxygen species was significantly increased in cells treated with PL at 20–40 μM. The expression of cyclin D1, CDK4, CDK6 and p-Rb were markedly decreased in cells treated with PL at 40 μM. Treatment of cells with PL suppressed phosphorylation of Akt but increased ERK1/2 phosphorylation. Treatment of PL significantly decreased nuclear translocation of NF-κB p65 in cells. These results suggest that PL possesses antiproliferative properties in A549 cells.

Therapeutic effect of methyl salicylate 2-O-β-d-lactoside on LPS-induced acute lung injury by inhibiting TAK1/NF-kappaB phosphorylation and NLRP3 expression

Acute lung injury (ALI), characterized by pulmonary edema and inflammatory cell infiltration, is a common syndrome of acute hypoxemic respiratory failure. Methyl salicylate 2-O-β-d-lactoside (MSL), a natural derivative of salicylate extracted from Gaultheria yunnanensis (Franch.) Rehder, was reported to have potent anti-inflammatory effects on the progression of collagen or adjuvant-induced arthritis in vivo and in vitro. The aim of this study is to investigate the therapeutic effect of MSL on lipopolysaccharide (LPS)-induced acute lung injury and reveal underlying molecular mechanisms. Our results showed that MSL significantly ameliorated pulmonary edema and histological severities, and inhibited IL-6 and IL-1β production in LPS-induced ALI mice. MSL also reduced MPO activity in lung tissues and the number of inflammatory cells in BALF. Moreover, we found that MSL significantly inhibited LPS-induced TAK1 and NF-κB p65 phosphorylation, as well as the expression of NLRP3 protein in lung tissues. Furthermore, MSL significantly inhibited LPS-induced TAK1 and NF-κB p65 phosphorylation in Raw264.7 cells. In addition, MSL significantly inhibited nuclear translocation of NF-κB p65 in cells treated with LPS in vitro. Taken together, our results suggested that MSL exhibited a therapeutic effect on LPS-induced ALI by inhibiting TAK1/NF-κB phosphorylation and NLRP3 expression.

Resolvin D1 inhibits multiple pro-inflammatory signaling pathways in primary human lung cells exposed to diverse inflammatory stimuli (IRM9P.721)

Abstract Resolution of inflammation is a bioactive process involving a new genus of lipid molecules called “specialized pro-resolving lipid mediators” (SPMs), mainly derived from dietary ω-3 polyunsaturated fatty acids, which actively antagonize inflammatory signaling pathways and promote resolution. Although it is broadly known that SPMs inhibit inflammation, the specific pathways and targets of many SPMs remained to be discovered. Here, we investigated the mechanism by which the SPM resolvin D1 (RvD1) inhibits pro-inflammatory signaling pathways using two distinct stimuli; IL-1β, which acts primarily via its own receptor, and poly(I:C), a double-stranded viral RNA mimetic that acts primarily through toll-like receptor (TLR)3. RvD1 inhibited production of pro-inflammatory mediators including IL-6 and IL-8, both primary human lung fibroblast and epithelial cell strains, when stimulated with either IL-1β or poly(I:C). RvD1 also blocked phosphorylation of ERK1/2 and translocation of NF-κB p65 in cells treated with both stimuli. Importantly, we found that RvD1 inhibited phosphorylation of TAK1, an upstream effector protein that regulates both the MAP-kinase and NF-κB pathways. These results demonstrate that RvD1 targets multiple pro-inflammatory signaling pathways and may have significant therapeutic potential in complex inflammatory diseases including pulmonary fibrosis, asthma and chronic obstructive pulmonary disease.

Peptide-Mediated Disruption of NFκB/NRF Interaction Inhibits IL-8 Gene Activation by IL-1 or Helicobacter pylori

Selective inhibition of proinflammatory chemokines such as IL-8 is an important approach to combat inflammatory and infection diseases. Previous studies suggested that interaction of transcription factors NFkappaB repressing factor (NRF) and NFkappaB play a crucial role in activation of IL-8 gene expression. In a search for a specific inhibitor of IL-8 expression, we applied tandem affinity purification to investigate interaction of NRF and NFkappaB p65 in cells. We identified a synthetic peptide corresponding to aa 223-238 of NRF interfering with binding of endogenous p65 to NRF. Furthermore, nucleofection experiments were established to introduce this inhibitory peptide into the nucleus of IL-1 stimulated human cervical and Helicobacter pylori infected gastric epithelial cells. Our data clearly show that the specific peptide disturbing NRF/NFkappaB interaction is able to significantly decrease endogenous IL-8 gene transcription in response to IL-1 or Helicobacter pylori infection. Thus, our study provides novel insights into NRF and NFkappaB interaction in vivo and may facilitate the design of new anti-IL-8 drugs based on novel strategies.