NADPH oxidase/ROS-dependent PYK2 activation is involved in TNF-α-induced matrix metalloproteinase-9 expression in rat heart-derived H9c2 cells

TNF-α plays a mediator role in the pathogenesis of chronic heart failure contributing to cardiac remodeling and peripheral vascular disturbances. The implication of TNF-α in inflammatory responses has been shown to be mediated through up-regulation of matrix metalloproteinase-9 (MMP-9). However, the detailed mechanisms of TNF-α-induced MMP-9 expression in rat embryonic-heart derived H9c2 cells are largely not defined. We demonstrated that in H9c2 cells, TNF-α induced MMP-9 mRNA and protein expression associated with an increase in the secretion of pro-MMP-9. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of ROS (N-acetyl-l-cysteine, NAC), NADPH oxidase [apocynin (APO) or diphenyleneiodonium chloride (DPI)], MEK1/2 (U0126), p38 MAPK (SB202190), JNK1/2 (SP600125), NF-κB (Bay11-7082), or PYK2 (PF-431396) and transfection with siRNA of TNFR1, p47^phox, p42, p38, JNK1, p65, or PYK2. Moreover, TNF-α markedly induced NADPH oxidase-derived ROS generation in these cells. TNF-α-enhanced p42/p44 MAPK, p38 MAPK, JNK1/2, and NF-κB (p65) phosphorylation and in vivo binding of p65 to the MMP-9 promoter were inhibited by U0126, SB202190, SP600125, NAC, DPI, or APO. In addition, TNF-α-mediated PYK2 phosphorylation was inhibited by NAC, DPI, or APO. PYK2 inhibition could reduce TNF-α-stimulated MAPKs and NF-κB activation. Thus, in H9c2 cells, we are the first to show that TNF-α-induced MMP-9 expression is mediated through a TNFR1/NADPH oxidase/ROS/PYK2/MAPKs/NF-κB cascade. We demonstrated that NADPH oxidase-derived ROS generation is involved in TNF-α-induced PYK2 activation in these cells. Understanding the regulation of MMP-9 expression and NADPH oxidase activation by TNF-α on H9c2 cells may provide potential therapeutic targets of chronic heart failure.     

Curcumin inhibits LPS-induced inflammation in rat vascular smooth muscle cells in vitro via ROS-relative TLR4-MAPK/NF-κB pathways

Aim:

To investigate whether curcumin (Cur) suppressed lipopolysaccharide (LPS)-induced inflammation in vascular smooth muscle cells (VSMCs) of rats, and to determine its molecular mechanisms.

Methods:

Primary rat VSMCs were treated with LPS (1 μg/L) and Cur (5, 10, or 30 μmol/L) for 24 h. The levels of MCP-1, TNF-α, and iNOS were measured using ELISA and real-time RT-PCR. NO level was analyzed with the Griess reaction. Western-blotting was used to detect the activation of TLR4, MAPKs, IκBα, NF-κB p65, and the p47^phox subunit of NADPH oxidase in the cells.

Results:

Treatment of VSMCs with LPS dramatically increased expression of inflammatory cytokines MCP-1 and TNF-α, expression of TLR4 and iNOS, and NO production. LPS also significantly increased phosphorylation of IκBα, nuclear translocation of NF-κB (p65) and phosphorylation of MAPKs in VSMCs. Furthermore, LPS significantly increased production of intracellular ROS, and decreased expression of p47^phox subunit of NADPH oxidase. Pretreatment with Cur concentration-dependently attenuated all the aberrant changes in LPS-treated VSMCs. The LPS-induced overexpression of MCP-1 and TNF-α, and NO production were attenuated by pretreatment with the ERK inhibitor PD98059, the p38 MAPK inhibitor SB203580, the NF-κB inhibitor PDTC or anti-TLR4 antibody, but not with the JNK inhibitor SP600125.

Conclusion:

Cur suppresses LPS-induced overexpression of inflammatory mediators in VSMCs in vitro via inhibiting the TLR4-MAPK/NF-κB pathways, partly due to block of NADPH-mediated intracellular ROS production.     

Urocortin induced expression of COX-2 and ICAM-1 via corticotrophin-releasing factor type 2 receptor in rat aortic endothelial cells

Background and purpose:

Our previous study showed that urocortin (Ucn1) exacerbates the hypercoagulable state and vasculitis in a rat model of sodium laurate-induced thromboangiitis obliterans. Furthermore, the inflammatory molecules COX-2 and ICAM-1 may participate in this effect. In the present study, the effects of Ucn1 on COX-2 and ICAM-1 expression in lipopolysaccharide (LPS)-induced rat aortic endothelial cells (RAECs) were investigated and the mechanisms involved explored.

Experimental approach:

RAECs were isolated from adult male Wistar rats, and identified at the first passage. Experiments were performed on cells, from primary culture, at passages 5–8. The expression of COX-2 and ICAM-1 at both mRNA and protein levels was determined by semi-quantitative RT-PCR and Western blot analysis. Levels of PGE₂ and soluble ICAM-1 (sICAM-1) in culture medium were measured by enzyme-linked immunosorbent assay. Furthermore, the phosphorylation status of p38MAPK, ERK1/2, JNK, Akt and NF-κB was analysed by Western blot; nuclear translocation of NF-κB was observed by immunofluorescence.

Key results:

Ucn1 augmented LPS-induced expression of COX-2 and ICAM-1 in RAECs in a time- and concentration-dependent manner. Ucn1 increased PGE₂ and sICAM-1 levels. These effects were abolished by the CRF₂ receptor antagonist, antisauvagine-30, but not by the CRF₁ receptor antagonist, NBI-27914. Moreover, Ucn2 activated p38MAPK and augmented NF-κB nuclear translocation and phosphorylation, whereas ERK1/2, JNK and Akt pathways were not involved in this process.

Conclusions and implications:

These findings suggest that Ucn1 exerts pro-inflammatory effects by augmenting LPS-induced expression of COX-2 and ICAM-1 in RAECs via CRF₂ receptors and the activation of p38MAPK and NF-κB.     

Activation of endothelial cells after exposure to ambient ultrafine particles: The role of NADPH oxidase

Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O₂⁻ generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67^phox siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91^phox knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47^phox, p67^phox and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67^phox siRNA. Exposure of MPMVEC obtained from gp91^phox knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs that may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that endothelial oxidative stress may be an important mechanism for PM-induced cardiovascular effects.     

Inhibition of arsenic-induced rat liver injury by grape seed exact through suppression of NADPH oxidase and TGF-β/Smad activation

Chronic arsenic exposure induces oxidative damage to liver leading to liver fibrosis. We aimed to define the effect of grape seed extract (GSE), an antioxidant dietary supplement, on arsenic-induced liver injury. First, Male Sprague-Dawley rats were exposed to a low level of arsenic in drinking water (30 ppm) with or without GSE (100 mg/kg, every other day by oral gavage) for 12 months and the effect of GSE on arsenic-induced hepatotoxicity was examined. The results from this study revealed that GSE co-treatment significantly attenuated arsenic-induced low antioxidant defense, oxidative damage, proinflammatory cytokines and fibrogenic genes. Moreover, GSE reduced arsenic-stimulated Smad2/3 phosphorylation and protein levels of NADPH oxidase subunits (Nox2, Nox4 and p47phox). Next, we explored the molecular mechanisms underlying GSE inhibition of arsenic toxicity using cultured rat hepatic stellate cells (HSCs). From the in vitro study, we found that GSE dose-dependently reduced arsenic-stimulated ROS production and NADPH oxidase activities. Both NADPH oxidases flavoprotein inhibitor DPI and Nox4 siRNA blocked arsenic-induced ROS production, whereas Nox4 overexpression suppressed the inhibitory effects of GSE on arsenic-induced ROS production and NADPH oxidase activities, as well as expression of TGF-β1, type I procollagen (Coll-I) and α-smooth muscle actin (α-SMA) mRNA. We also observed that GSE dose-dependently inhibited TGF-β1-induced transactivation of the TGF-β-induced smad response element p3TP-Lux, and that forced expression of Smad3 attenuated the inhibitory effects of GSE on TGF-β1-induced mRNA expression of Coll-I and α-SMA. Collectively, GSE could be a potential dietary therapeutic agent for arsenic-induced liver injury through suppression of NADPH oxidase and TGF-β/Smad activation.     

Anthocyanidins inhibit cyclooxygenase-2 expression in LPS-evoked macrophages: structure-activity relationship and molecular mechanisms involved

The effects of anthocyanidins, the aglycon nucleuses of anthocyanins widely occurring in reddish fruits and vegetables, on the expression of cyclooxygenase-2 (COX-2) were investigated in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. Of five anthocyanidins, delphinidin and cyanidin inhibited LPS-induced COX-2 expression, but pelargonidin, peonidin and malvidin did not. The structure-activity relationship suggest that the ortho-dihydroxyphenyl structure of anthocyanidins on the B-ring appears to be related with the inhibitory actions. Delphinidin, the most potent inhibitor, caused a dose-dependent inhibition of COX-2 expression at both mRNA and protein levels. Western blotting analysis indicated that delphinidin inhibited the degradation of IkappaB-alpha, nuclear translocation of p65 and CCAAT/enhancer-binding protein (C/EBP)delta and phosphorylation of c-Jun, but not CRE-binding protein (CREB). Moreover, delphinidin suppressed the activations of mitogen-activated protein kinase (MAPK) including c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 kinase. MAPK inhibitors (U0126 for MEK1/2, SB203580 for p38 kinase and SP600125 for JNK) specifically blocked LPS-induced COX-2 expression. Thus, our results demonstrated that LPS-induced COX-2 expression by activating MAPK pathways and delphinidin suppressed COX-2 by blocking MAPK-mediated pathways with the attendant activation of nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and C/EBPdelta. These findings provide the first molecular basis that anthocyanidins with ortho-dihydroxyphenyl structure may have anti-inflammatory properties through the inhibition of MAPK-mediated COX-2 expression.     

小檗碱对p38MAPK通路及COX-2mRNA表达的作用

目的研究中药小檗碱是否通过p38MAPK信号转导途径抑制人外周血单核细胞COX-2mRNA及蛋白表达。方法取人外周静脉血分离及培养单核细胞,分为对照组、脂多糖(LPS)组、LPS+小檗碱25μmol/L组、LPS+小檗碱50μmol/L组、LPS+小檗碱100μmol/L组。分别在培养后0.5、6、12、24h提取细胞,行RT-PCR法测定COX-2mRNA水平,行Westernblot法测定p38MAPK、p-p38MAPK及COX-2蛋白水平。同时加入选择性p38MAPK抑制剂,分别测定COX-2mRNA及蛋白水平。结果与对照组相比,LPS组COX-2mRNA及蛋白表达明显增强(P<0.01)。与LPS组相比,小檗碱组COX-2mRNA及蛋白表达明显抑制(P<0.05),且随着浓度增加,抑制作用更明显,在给药后12h,小檗碱对COX-2抑制作用最强,但是与LPS组相比,小檗碱组p38MAPK活性水平无明显统计学差异(P>0.05)。加入p38MAPK抑制剂之后,COX-2mRNA及蛋白水平降低明显(P<0.05)。结论小檗碱能抑制人外周血单核细胞COX-2mRNA及蛋白水平,并呈浓度依赖性,p38MAPK与人外周血COX-2表达有关,而小檗碱对p38MAPK活性蛋白表达无明显抑制作用。     

原花青素对脂多糖诱导RAW2647细胞COX-2酶活性、mRNA及蛋白表达的影响

目的探讨原花青素对脂多糖(LPS)诱导小鼠巨噬细胞株RAW264.7细胞COX-2酶活性及蛋白表达的影响。方法放射免疫法检测COX-2酶活性，RT-PCR检测COX-2 mRNA表达，Western blotting检测COX-2蛋白表达。结果原花青素(0.8，4和20 mg·L^-1)不影响LPS诱导RAW264.7细胞COX-2酶活性，可下调LPS诱导RAW264.7细胞COX-2 mRNA表达；原花青素(4和20 mg·L^-1)下调LPS诱导RAW264.7细胞COX-2蛋白表达。结论原花青素不影响LPS诱导RAW2647细胞COX-2酶活性，但对LPS诱导RAW264.7细胞COX-2 mRNA及蛋白表达抑制作用明显。     

Ethyl acetate extract from Angelica Dahuricae Radix inhibits lipopolysaccharide-induced production of nitric oxide, prostaglandin E2 and tumor necrosis factor-alphavia mitogen-activated protein kinases and nuclear factor-kappaB in macrophages.

Angelica dahurica (Umbelliferae) has been used to treat headache of common cold, supraorbital neuralgia, painful swelling on the body, nasal stuffiness, leukorrhea and arthralgia due to wind-dampness in Korean traditional medicine. It is also claimed to be effective in the treatment of acne, erythema, headache, toothache, sinusitis, colds and flu. The present study focused whether the ethyl acetate extract from Angelica Dahuricae Radix (EAAD) inhibits production of nitric oxide (NO), prostaglandin E(2) (PGE(2)) and tumor necrosis factor (TNF)-alpha, as well as expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinases (MAPKs) in lipopolysaccharide (LPS)-stimulated macrophages. EAAD inhibited LPS-induced NO, PGE(2) and TNF-alpha production as well as expression of iNOS and COX-2 in RAW 264.7 cells. EAAD inhibited LPS-induced TNF-alpha production in THP-1 cells. Furthermore, EAAD suppressed LPS-induced phosphorylation of p38 MAPK and extracellular-signal regulated kinases 1/2 (ERK1/2), I-kappaBalpha degradation, and NF-kappaB activation in RAW 264.7 cells. These results suggest that EAAD has the inhibitory effects on LPS-induced TNF-alpha, NO and PGE(2) production, and expression of iNOS and COX-2 in macrophage through blockade in the phosphorylation of MAPKs, following I-kappaBalpha degradation and NF-kappaB activation.     

Kaempferol acts through mitogen-activated protein kinases and protein kinase B/AKT to elicit protection in a model of neuroinflammation in BV2 microglial cells

BACKGROUND AND PURPOSE

Kaempferol, a dietary flavonoid and phyto-oestrogen, is known to have anti-inflammatory properties. Microglial activation has been implicated in various neurodegenerative diseases. Anti-inflammatory effects of kaempferol and the underlying mechanisms were investigated by using LPS-stimulated microglial BV2 cells.

EXPERIMENTAL APPROACH

Cell viability was measured using MTT and neutral red assays. elisa, Western blot, immunocytochemistry and electrophoretic mobility-shift assay were used to analyse NO, PGE₂, TNF-α and IL-1β production, inducible NOS (iNOS), COX-2 expression and the involvement of signalling pathways such as toll-like receptor-4 (TLR4), MAPK cascades, PKB (AKT) and NF-κB. Accumulation of reaction oxygen species (ROS) was measured by nitroblue tetrazolium and 2′7′-dichlorofluorescein diacetate assay. Matrix metalloproteinase activity was investigated by zymography and immunoblot assay. Phagocytotic activity was assessed by use of latex beads.

KEY RESULTS

Kaempferol significantly attenuated LPS-induced NO, PGE₂, TNF-α, IL-1β and ROS production and phagocytosis in a concentration-dependent manner. Kaempferol suppressed the expression of iNOS, COX-2, MMP-3 and blocked the TLR4 activation. Moreover, kaempferol inhibited LPS-induced NF-κB activation and p38 MAPK, JNK and AKT phosphorylation.

CONCLUSION AND IMPLICATIONS

Kaempferol was able to reduce LPS-induced inflammatory mediators through the down-regulation of TLR4, NF-κB, p38 MAPK, JNK and AKT suggesting that kaempferol has therapeutic potential for the treatment of neuroinflammatory diseases.     

Tumor necrosis factor-alpha-induced cyclooxygenase-2 expression via sequential activation of ceramide-dependent mitogen-activated protein kinases, and IkappaB kinase 1/2 in human alveolar epithelial cells

The role of p44/42 mitogen-activated protein kinase (MAPK), p38, and c-Jun NH(2)-terminal kinase (JNK) in tumor necrosis factor (TNF)-alpha-induced cyclooxygenase (COX)-2 expression was studied in NCI-H292 epithelial cells. TNF-alpha-mediated COX-2 expression and COX-2 promoter activity were inhibited by the MAPK kinase inhibitor PD98059 or the p38 inhibitor SB203580. Treatment of cells for 10 min with TNF-alpha resulted in activation of p44/42 MAPK, p38, and JNK. C2-ceramide (a cell-permeable ceramide analog), bacterial neutral sphingomyelinase (Smase; an enzyme that degrades sphingomyelin to ceramide), and N-oleoylethanolamine (a ceramidase inhibitor) all induced activation of MAPKs, COX-2 expression, nuclear factor (NF)-kappaB DNA-protein binding, and COX-2 promoter activity. The inactive analog, dihydro-C2-ceramide, had no effect. SMase- or C2-ceramide-induced COX-2 expression and COX-2 promoter activity were also inhibited by PD98059 or SB203580. Glutathione, a neutral SMase inhibitor, attenuated TNF-alpha- or SMase-induced activation of MAPKs, COX-2 expression, and COX-2 promoter activity. TNF-alpha- or C2-ceramide-induced COX-2 promoter activity was inhibited by the dominant negative mutant of extracellular signal-regulated kinase 2, p38, JNK, IkappaB kinase (IKK)1, or IKK2. IKK activity was stimulated by either TNF-alpha or C2-ceramide, and these effects were inhibited by PD98059 or SB203580. All these results suggest that, in NCI-H292 epithelial cells, activation of MAPKs by ceramide contributes to the TNF-alpha signaling that occurs downstream of neutral SMase activation and results in the stimulation of IKK1/2, and NF-kappaB in the COX-2 promoter, followed by initiation of COX-2 expression.     

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent activation of phosphoinositide 3-kinase and p38 mitogen-activated protein kinase signal pathways is required for lipopolysaccharide-induced microglial phagocytosis

The importance of microglial reactive oxygen species (ROS) signaling in neuroinflammatory processes has been well demonstrated; however, relatively little is known regarding the related mechanisms underlying these processes. Here, we show that ROS-dependent signal pathways that govern microglial phagocytosis are highly dependent upon nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) activation. Specifically, phagocytosis was greatly reduced by both antioxidant and Nox inhibitor treatments in lipopolysaccharide (LPS)-stimulated BV-2 microglia. Additionally, there was a marked reduction in intracellular ROS content. These results suggest that Nox is the main ROS source for LPS-induced microglial phagocytosis. More decisive evidence for the involvement of ROS in phagocytosis was obtained from an examination of phosphatidyl inositol 3-kinase (PI3-K) and p38 mitogen-activated protein kinase (MAPK) signal pathway activation under reduced ROS levels. These two kinases were activated by LPS treatment and inhibited by ROS neutralization and Nox inhibition. We conclude that microglial phagocytosis requires ROS-dependent PI3-K and p38 MAPK activation and that Nox-derived ROS functions as an upstream regulator of both PI3-K and p38 MAPK. These findings will provide a fundamental basis for a therapeutic modality in inflammation-mediated neurodiseases.