Oleamide suppresses lipopolysaccharide-induced expression of iNOS and COX-2 through inhibition of NF-κB activation in BV2 murine microglial cells

Oleamide (cis-9-octadecenamide) is an endogenous sleep-inducing fatty acid amide that accumulates in the cerebrospinal fluid of the sleep-deprived animals. Microglia are the major immune cells involved in neuroinflammation causing brain damage during infection, ischemia, and neurodegenerative disease. In this study, we examined the effects of oleamide on LPS-induced production of proinflammatory mediators and the mechanisms involved in BV2 microglia. Oleamide inhibited LPS-induced production of NO and prostaglandin E2 as well as expression of iNOS and COX-2. We showed that oleamide blocked LPS-induced NF-κB activation and phosphorylation of inhibitor κB kinase (IKK). We also showed that oleamide inhibited LPS-induced phosphorylation of Akt, p38 MAPK, and ERK, activation of PI 3-kinase, and accumulation of reactive oxygen species (ROS). Finally, we showed that a specific antagonist of the CB2 receptor, AM630, blocked the inhibitory effects of oleamide on LPS-induced production of proinflammatory mediators and activation of NF-κB. Taken together, our results suggest that oleamide shows an anti-inflammatory effect through inhibition of NF-κB activation in LPS-stimulated BV2 microglia.     

Activation of Akt leading to NF-κB up-regulation in chondrocytes stimulated with fibronectin fragment

Increased fibronectin fragments are thought to contribute to joint destruction in osteoarthritis (OA). However, the mechanism whereby fibronectin fragments cause catabolic activities is not totally understood. While COOH-terminal heparin-binding fibronectin fragment (HBFN-f) has been shown to activate nuclear factor (NF)-κB pathway, intracellular upstream events that cause NF-κB up-regulation in response to HBFN-f remain unclear. Thus, this study was aimed to elucidate the involvement of phosphoinositide-3-OH kinase (PI3K)/Akt pathway in NF-κB activation by HBFN-f in OA chondrocytes. In chondrocyte monolayer cultures, HBFN-f stimulated nitric oxide (NO) production in association with phosphorylation of NF-κB and Akt. Inhibition studies using LY294002 revealed the requirement of PI3K/Akt pathway for NO production and NF-κB activation by HBFN-f. Anti-CD44 treatment with anti-CD44 antibody and hyaluronan resulted in significant inhibition of HBFN-f actions on NO, NF-κB, and Akt. Herein, we provided the first evidence that HBFN-f activates PI3K/Akt pathway leading to up-regulation of NF-κB through interaction with CD44.     

HBV X Protein induces overexpression of HERV-W env through NF-κB in HepG2 cells

Human endogenous retrovirus W family (HERV-W) envelope (env) at chromosome 7 is highly expressed in the placenta and possesses fusogenic activity in trophoblast development. HERV-W env has been found to be overexpressed in some cancers and immune diseases. Viral transactivators can induce the overexpression of HERV-W env in human cell lines. Hepatitis B virus X protein (HBx) is believed to be a multifunctional oncogenic protein. Here, we reported that HBx could increase the promoter activity of HERV-W env and upregulate the mRNA levels of non-spliced and spliced HERV-W env and also its protein in human hepatoma HepG2 cells. Interestingly, we found that the inhibition of nuclear factor κB (NF-κB) using shRNA targeting NF-κB/p65 or PDTC (an inhibitor of NF-κB) could attenuate the upregulation of HERV-W env induced by HBx. These suggested that HBx might upregulate the expression of HERV-W env through NF-κB in HepG2 cells. This study might provide a new insight in HBV-associated liver diseases including HCC.     

Dexamethasone Attenuates LPS-induced Acute Lung Injury through Inhibition of NF-κB,COX-2, and Pro-inflammatory Mediators

Dexamethasone (DEX) is a synthetic glucocorticoid with potent anti-inflammatory effects that is widely used to treat inflammatory diseases. The aim of the present study was to investigate the possible protective effect of DEX on the lipopolysaccharides (LPS)-induced acute lung injury (ALI) in a mouse model. Animals were pretreated with DEX (5 and 10 mg/kg, i.p.) for seven days and acute lung injury was induced by intranasal (i.n.) administration of LPS on day 7. In the present study, administration of LPS resulted in significant increase in neutrophils and lymphocytes count whereas a substantial reduction in T cell subsets (CD3⁺ and CD4⁺) and pro-inflammatory (IL-6 and TNF-α) cytokines occurred, which were reversed by DEX treatment. RT-PCR analysis revealed an increased mRNA expression of IL-6, TNF-α, COX-2, iNOS, and NF-κB p65 and decreased IL-10 in the LPS group, which were reversed by treatment with DEX in lung tissues. Western blot analysis revealed an increased expression of COX-2, iNOS and NF-κB p65 in the LPS-group, which was reduced by treatment with DEX. Compared with the LPS group, the DEX treatment also demonstrated a considerable increase in the protein expression level of IL-10 cytokine. Administration of LPS resulted in marked increase in malondialdehyde (MDA) levels and myeloperoxidase (MPO) activity whereas noticeable decrease in glutathione (GSH) content. These changes were significantly reversed by treatment with DEX. The histological examinations revealed protective effect of DEX while LPS group aggravated lung injury. The present findings demonstrate the potent anti-inflammatory action of the DEX against acute lung injury induced by LPS.     

Role of NF-κB in epithelial biology

Since its discovery, nuclear factor-κB (NF-κB) has been recognized as a critical regulator of immune responses. While early studies focused on studying the role of NF-κB in the development and function of immune cells, more recently the function of the inhibitor of NF-κB kinase (IKK)/NF-κB pathway in non-immune cells has gained increased attention. Studies in genetic mouse models were instrumental in dissecting the cell-specific functions of NF-κB and provided experimental evidence that NF-κB signaling in epithelial cells is important for the maintenance of immune homeostasis in barrier tissues such as the skin and the intestine. Increased activation of IKK/NF-κB triggered cytokine expression by the epithelial cells, resulting in exacerbated tissue inflammatory responses. NF-κB inhibition in keratinocytes triggered severe tumor necrosis factor-dependent skin inflammation and epidermal hyperplasia, while inhibition of IKK/NF-κB signaling in intestinal epithelial cells disturbed the intestinal barrier and triggered severe chronic colon inflammation. Therefore, epithelial NF-κB signaling performs critical 'peace keeping' functions in barrier tissues at the interface with the environment by regulating cell survival, barrier integrity, and the immunological and anti-microbial responses of epithelial cells. Improved understanding of epithelial NF-κB functions may hold the key for elucidating the etiology and pathophysiology of chronic inflammatory diseases in epithelial tissues.     

Gomisin A decreases the LPS-induced expression of iNOS and COX-2 and activation of RIP2/NF-κB in mouse peritoneal macrophages

Gomisin A (GA), a lignan component contained in the fruit of Schisandra chinensis Baillon, improves hepatic cell degeneration, vasodilatory activity and insulin sensitivity. These effects also impact the immune system, including various inflammatory mediators and cytokines. In this study, the anti-inflammatory effect of GA on lipopolysaccharide-stimulated mouse peritoneal macrophages was studied. Pretreatment with GA attenuated the expression of receptor-interacting protein 2 (RIP2) and IκB kinase-β (IKK-β) as well as IKK-β phosphorylation. The activation of nuclear factor-kappa B (NF-κB) in the nucleus, the phosphorylation of IκBα and degradation of IκBα in the cytosol were suppressed by GA. GA decreased the production and mRNA expression of the inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6. In addition, expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and production of nitric oxide were decreased by pretreatment with GA. In conclusion, these results show that the anti-inflammatory properties of GA potentially result from the inhibition of COX-2, iNOS, IL-6, TNF-α and NO through the down-regulation of RIP2 and NF-κB activation. These results impact the development of potential health products for preventing and treating inflammatory diseases.     

Isorhamnetin ameliorates LPS-induced inflammatory response through downregulation of NF-κB signaling

Isorhamnetin, a flavonoid mainly found in Hippophae fhamnoides L. fruit, has been known for its antioxidant activity and its ability to regulate immune response. In this study, we investigated whether isorhamnetin exerts potent antiinflammatory effects in RAW264.7 cell and mouse model stimulated by LPS. The cytokine (TNF-α, IL-1β, and IL-6) levels were determined. In the mouse model of acute lung injury, the phosphorylation of NF-κB proteins was analyzed and inhibitor of NF-κB signaling (PDTC) was used on mice. Our results showed that isorhamnetin markedly decreased TNF-α, IL-1β, and IL-6 concentrations and suppressed the activation of NF-κB signaling. Meanwhile, isorhamnetin reduced the amount of inflammatory cells, the lung wet-to-dry weight ratio, protein leakage, and myeloperoxidase activity. Interference with specific inhibitor revealed that isorhamnetin-mediated suppression of cytokines and protein was via NF-κB signaling. So, it suggests that isorhamnetin might be a potential therapeutic agent for preventing inflammatory diseases.     

Baicalin suppresses expression of TLR2/4 and NF-κB in chlamydia trachomatis-infected mice

Our previous studies have shown that the baicalin could blocked infection of chlamydia trachomatis (C. trachomatis)-infected cells in vitro. Toll-like receptor 2 and 4 (TLR2/4) and the downstream nuclear factor-κB (NF-κB) signaling pathway, which mediate the inflammatory reaction, are involved in the pathophysiological processes of inflammation. In this study, we investigated whether baicalin inhibits TLR2/4 signaling pathway in gential tract chlamydia-infected mice. The progesterone-treated animals were given intravaginally 200?mg/kg baicalin administered. Nineteen days after infection, cervical tissue were taken and expression of TLR2/4, NF-κB were determined by RT-PCR or westernblot. Nitric oxide and prostaglandin E2 production in cervical tissue were detected by enzyme-linked immunosorbent assay. It was demonstrated that baicalin significantly reduced C. trachomatis loading in BALB/c mice that were vaginally infected with the pathogen. Meanwhile, baicalin also reduced the expression of TLR2/4 and NF-κB, decreased activity of inducible nitric oxide synthase and cyclooxgenase-2 in cervical tissue. Our results suggest that baicalin inhibits the TLR2/4 signaling pathway in cervical tissue of gential tract chlamydia-infected mice. On the basis of these data and our previous observations, we conclude that further evaluation of baicalin for prevention and treatment of sexually transmitted chlamydial infection is warranted.     

胃癌组织中NF-κB和COX-2的表达及临床意义

目的：探讨核因子-κB（nuclear factor-kappa B,NF-κB）和环氧合酶-2(cyclooxygenase-2,COX-2)的表达与胃癌发生发展的关系,为开展以NF-κB和COX-2为靶标的胃癌防治提供理论依据。方法：采用免疫组织化学染色法（SP法）检测对照组10例正常胃黏膜及实验组50例胃癌组织中NF-κB和COX-2的表达情况,分析它们在不同组织中的表达、相互关系及与胃癌的关系。结果：实验组NF-κB和COX-2的表达阳性率明显高于对照组（P<0.001）;NF-κB表达与胃癌淋巴结转移、分化程度有关（P<0.05）,COX-2 表达与淋巴结转移有关（P<0.05）;胃癌组织中NF-κB与COX-2的表达呈正相关关系,相关系数r=0.5238 （P<0.01）。结论：NF-κB和COX-2参与胃癌的形成,且与胃癌的侵袭、转移及预后有一定的关系。NF-κB与COX-2表达呈正相关,提示它们在胃癌的发生发展中起协同作用。     

Saturated Fatty Acids Up-regulate COX-2 Expression in Prostate Epithelial Cells via Toll-like Receptor 4/NF-κB Signaling

Cyclooxygenase-2 (COX-2) has been implicated in prostate carcinogenesis, and recently it has been confirmed to be a molecular target of saturated fatty acids (SFAs). In the present study, we investigated the effect of stearic acid (SA) and palmitic acid (PA), two of the most abundant SFAs contained in dietary fat, on COX-2 expression in prostate epithelial cells and the signaling transduction pathway involved. First, we demonstrated that both SA and PA increased the mRNA and protein expression of COX-2, and consistently induced the activation of NF-κB in RWPE-1, BPH-1 and PC-3 prostate epithelial cell lines. The effect of SA and PA on COX-2 over-expression and NF-κB activation was in a dose-dependent manner, and PA was more potent than SA at the same concentration. Then, we demonstrated inhibition of NF-κB using its specific inhibitor strikingly attenuated PA-induced COX-2 expression. Toll-like receptor 4 (TLR4) was revealed to be expressed on RWPE-1, BPH-1 and PC-3 cell lines by PCR and immunofluorescence staining, and blocking its signaling significantly inhibited PA induced COX-2 over-expression and NF-κB activation. Taken together, we demonstrated that SFAs can up-regulate COX-2 expression in prostate epithelial cells, and this effect was mediated mainly through the TLR4/NF-κB signaling pathway.     

Anti-inflammation of apelin in ameliorating hypoxic pulmonary artery hypertension is through an inhibition of NF-κB pathway

<正>AIM:To investigate whether anti-inflammation of apelin in amelioration of hypoxic pulmonary artery hypertension(HPAH)was through an inhibition of nuclear factor-κB(NF-κB)pathway.METHODS:The mice were exposed in a normobaric hypoxic chamber with a fraction of inspired oxygen(FiO 2)of~10%,or hypoxia combined with apelin application,23 h/d,continued for 2 weeks.     

The Anti-Death Machinery in IKK/NF-κB Signaling

The most extensively studied function of NF-κB is its ability to promote cell survival through induction of target genes, whose products inhibit various aspects of the apoptotic machinery in both normal and malignant cells. Recent studies, however, indicate that NF-κB activation can also suppress programmed necrosis through induction of genes encoding anti-oxidant proteins. Since tumor cells often use NF-κB pathway as a shield to escape the killing of conventional anti-cancer therapies, intervention of IKK/NF-κB signaling would be a promising option to improve the efficacy of cancer treatment.