Inhibition of p38 and ERK MAP kinases blocks endotoxin-induced nitric oxide production and differentially modulates cytokine expression.

Mitogen-activated protein kinases (MAPKs) are thought to have a critical role in lipopolysaccharide (LPS)-induced immune responses but the molecular mechanisms underlying the mediation of these signaling are not clear. The roles of p38 and extracellular signal-regulated kinase (ERK) in the regulation of nitric oxide (NO) and proinflammatory cytokine expression in J774A.1 macrophages in response to LPS were examined. Specific inhibitors for p38 and ERK, SB203580 and PD98059, respectively, were used. LPS (30ng/ml) activated inducible nitric oxide synthase (iNOS), subsequent NO production, and gene expression for tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-12. Treatment of cultures with SB203580 increased LPS-induced reactive oxygen species (ROS) production, whereas both SB203580 and PD98059 decreased LPS-induced NO production. Concomitant decreases in the expression of iNOS mRNA and protein were detected. SB203580 and PD98059 decreased LPS-induced gene expression of IL-1beta and IL-6. SB203580 increased LPS-induced expression of TNF-alpha and IL-12; PD98059 had no effect on these cytokines. Results indicated that both p38 and ERK pathways are involved in LPS-stimulated NO synthesis and the expression of IL-1beta and IL-6. p38 signaling pathway is involved in LPS-induced ROS, TNF-alpha and IL-12 production.     

脂多糖刺激体外大鼠小胶质细胞产生细胞肽和一氧化氮

AIM: To study the characterization of interleukin (IL)-1, IL-2, tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) production in microglia stimulated with lipopolysaccharides (LPS). METHODS: Primary cultured neonatal rat microglia were incubated with LPS (0-10 mg.L-1) for 0-72 h. The supernatants and lysates were collected. IL-1, IL-2, and TNF-alpha were assayed by mouse thymocyte proliferation, mouse spleen cell proliferation, and 1929 cytotoxity, respectively. NO was assayed by Griess reaction. RESULTS: Extracellular IL-1, TNF-alpha, and NO production reached peak levels at LPS 1 mg.L-1. Intracellular IL-1 production reached its peak level at LPS 100 micrograms.L-1. Intracellular TNF-alpha level was very low. IL-1, TNF-alpha, and NO activities were detected at 1, 4, and 8 h, after the cells were stimulated with LPS. IL-1 got to its peak value at 8 h, TNF-alpha, and NO reached the highest levels at 24 h. However, IL-2 activity was not detected after the microglia were stimulated with LPS 0-10 mg.L-1 during the incubation period. CONCLUSION: Rat microglia stimulated with LPS in vitro produced proinflammatory cytokines and NO.     

Tanshinone IIA from Salvia miltiorrhiza inhibits inducible nitric oxide synthase expression and production of TNF-alpha, IL-1beta and IL-6 in activated RAW 264.7 cells

The inhibitory effects of tanshinone IIA, a diterpene isolated from Salvia miltiorrhiza root, on the production of nitric oxide (NO), interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), and the expression of inducible nitric oxide synthase (iNOS) were investigated in activated RAW 264.7 cells. This compound markedly inhibited the production of NO, IL-1beta and TNF-alpha, and suppressed the expression of iNOS in a dose-dependent manner. These results suggest that the traditional use of S. miltiorrhiza as an anti-inflammatory herbal medicine may be explained, in part, by the inhibition of NO, IL-1beta, IL-6 and TNF-alpha production, and expression of iNOS.     

Role of inducible nitric oxide synthase-derived nitric oxide in lipopolysaccharide plus interferon-gamma-induced pulmonary inflammation

Exposure of mice to lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) increases nitric oxide (NO) production, which is proposed to play a role in the resulting pulmonary damage and inflammation. To determine the role of inducible nitric oxide synthase (iNOS)-induced NO in this lung reaction, the responses of inducible nitric oxide synthase knockout (iNOS KO) versus C57BL/6J wild-type (WT) mice to aspirated LPS + IFN-gamma were compared. Male mice (8-10 weeks) were exposed to LPS (1.2 mg/kg) + IFN-gamma (5000 U/mouse) or saline. At 24 or 72 h postexposure, lungs were lavaged with saline and the acellular fluid from the first bronchoalveolar lavage (BAL) was analyzed for total antioxidant capacity (TAC), lactate dehydrogenase (LDH) activity, albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and AM zymosan-stimulated chemiluminescence (AM-CL). Pulmonary responses 24 h postexposure to LPS + IFN-gamma were characterized by significantly decreased TAC, increased BAL AMs and PMNs, LDH, albumin, TNF-alpha, and MIP-2, and enhanced AM-CL to the same extent in both WT and iNOS KO mice. Responses 72 h postexposure were similar; however, significant differences were found between WT and iNOS KO mice. iNOS KO mice demonstrated a greater decline in total antioxidant capacity, greater BAL PMNs, LDH, albumin, TNF-alpha, and MIP-2, and an enhanced AM-CL compared to the WT. These data suggest that the role of iNOS-derived NO in the pulmonary response to LPS + IFN-gamma is anti-inflammatory, and this becomes evident over time.     

Stylopine from<Emphasis Type="Italic">Chelidonium majus</Emphasis> inhibits LPS-Induced inflammatory mediators in RAW 264.7 cells

Stylopine is a major component of the leaf of Chelidonium majus L. (Papaveraceae), which has been used for the removal of warts, papillomas and condylomas, as well as the treatment of liver disease, in oriental countries. Stylopine per se had no cytotoxic effect in unstimulated RAW 264.7 cells, but concentration-dependently reduced nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), and the IL-6 production and cyclooxygenase-2 (COX-2) activity caused by the LPS stimulation. The levels of inducible nitric oxide synthase (iNOS) and COX-2 protein expressions were markedly suppressed by stylopine in a concentration dependent manner. These results suggest that stylopine suppress the NO and PGE2 production in macrophages by inhibiting the iNOS and COX-2 expressions. These biological activities of stylopine may contribute to the anti-inflammatory activity of Chelidonium majus.     

Lipopolysaccharide-induced down-regulation of organic anion transporting polypeptide 4 (Oatp4; Slc21a10) is independent of tumor necrosis factor-alpha, Interleukin-1beta, interleukin-6, or inducible nitric oxide synthase.

Organic anion transporting polypeptide 4 (Oatp4; Slc21a10) is expressed almost exclusively in liver, where it mediates uptake of a variety of compounds, including bile acids, as well as other endo- and xenobiotics, across hepatic sinusoidal membranes in a Na+-independent manner. Lipopolysaccharide (LPS) has been shown to decrease Oatp4 mRNA levels in a dose- and time-dependent manner in Toll-like receptor 4 (TLR4)-normal (C3H/OuJ) mice, but not in TLR4-mutant (C3H/HeJ) mice. Moreover, after LPS administration, serum concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) are markedly lower in TLR4-mutant mice than in TLR4-normal mice. Thus, TLR4 is considered an upstream mediator of LPS-induced decrease in mouse Oatp4 mRNA. LPS is thought to alter liver gene expression through LPS-induced cytokines or nitric oxide (NO). TNF receptor p55 (TNFRp55) and type I IL-1 receptor (IL-1RI) mediate the biological functions of TNF-alpha and IL-1beta, respectively. Therefore, to determine whether endogenous cytokines or NO are mediators of LPS-induced down-regulation of Oatp4, Oatp4 mRNA levels were determined in mice deficient in the TNFRp55, IL-1RI, IL-6, or inducible nitric oxide synthase (iNOS) after LPS administration. Mice homozygous for a targeted deletion of genes for TNFRp55, IL-1RI, IL-6, or iNOS exhibited similar decreases in Oatp4 mRNA levels as wild-type mice after LPS administration. Moreover, in mouse hepatoma cells, treatment with TNF-alpha, IL-1beta, or IL-6 individually or in combination did not suppress activity of mouse Oatp4 promoter (-4.8 kb to +30). Therefore, LPS-induced down-regulation of Oatp4 appears to be independent of TNF-alpha, IL-1beta, IL-6, or iNOS.     

Protective and anti-inflammatory effect of a traditional Chinese medicine, Xia-Bai-San, by modulating lung local cytokine in a murine model of acute lung injury

We investigated the effects of Xia-Bai-San (XBS) on acute lung inflammation induced by LPS in vivo. Mice were challenged with intratracheal lipopolysaccharide (100 microg) 30 min before administering XBS (1 mg/kg oral administration). Bronchoalveolar lavage fluid (BALF) was obtained after 4 and 24 h to measure proinflammatory cytokine (TNF-alpha, IL-1beta, IL-6), anti-inflammatory cytokines (IL-10), chemokines (KC, MCP-1 and MIP-2), total cell counts, nitric oxide production, and proteins. The results indicated that XBS down-regulated the LPS-induced expression of TNF-alpha, IL-1beta, IL-6, KC, MIP-2, and MCP-1. Furthermore, it also enhanced the production of IL-10, which had increased 24 h after LPS challenge. In addition, total leukocyte counts, nitric oxide production, iNOS expression, and BALF's proteins had significantly decreased 24 h after LPS challenge. XBS was also believes to have reduced the acute inflammation by attenuating the activation of NF-kappaB. In conclusion, XBS seem to suppress lipopolysaccharide-induced lung inflammation by stimulating the production of anti-inflammatory cytokines in lung. These results suggest that XBS could be a useful adjunct in the treatment of acute respiratory distress syndrome.     

Cytokines, growth factors, and oxidative stress in HepG2 cells treated with ethanol, acetaldehyde, and LPS.

Inflammatory mediators, including cytokines, growth factors, and reactive oxygen species, are associated with the pathology of chronic liver disease. In the liver, cytokine and growth factor secretion are usually associated with nonparenchymal cells, particularly Kupffer cells. In the present studies, the effect of 24 and 72 h administration of ethanol (50 mM). acetaldehyde (175 microM), and LPS (1 microg/ml) were studied on the expression and secretion of TNF-alpha, IL-1beta, IL-6, and TGF-beta3, lipid peroxidation damage and glutathion content in HepG2 cell cultures. A 24 h exposure to ethanol induced the expression of TNF-alpha and TGF-beta1, and the secretion of IL-1beta and TGF-beta1. With the same period of treatment, acetaldehyde markedly increased TNF-alpha expression, and stimulated IL-1beta secretion, while LPS exposure induced the expression of TNF-alpha, IL-6, and TGF-beta1, and the secretion of IL-1beta, IL-6, and TGF-beta1. A reduced in TNF-alpha response and TGF-beta1 expression were observed after 72 h exposure to ethanol. A 72 h acetaldehyde exposure decreased markedly TNF-alpha expression and stimulated a previously absent TGF-beta1 response. With the same time of exposure, LPS reduced slightly TGF-beta1 expression, and decreased its secretion. IL-1beta and IL-6 were not detected under 72 h exposure conditions. Lipid peroxidation damage was increased in all treatments, but higher values were found in 72 h treatments. Glutathion content diminished in all treatments. These findings suggest that HepG2 cells, independent of other cells such as Kupffer or macrophages, participate in a differential cytokine, growth factor and oxidative stress response, which differs according to the toxic agent and the time of exposure.     

Styraxoside A isolated from the stem bark of Styrax japonica inhibits lipopolysaccharide-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 in RAW 264.7 cells by suppressing nuclear factor-kappa B activation

In the present study, the effects of terpenes (styraxosides A and B) and lignans (egonol, masutakeside I, and styraxlignolide A) isolated from the stem bark of Styrax japonica Sieb. et Zucc. (styracaceae) were evaluated on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production by the RAW 264.7 macrophage cell line. Of the tested compounds, styraxoside A was found to most potently inhibit the productions of NO and PGE2, and also significantly reduced the release of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Consistent with these observations, the protein expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and the mRNA expression levels of iNOS, COX-2, TNF-alpha and IL-1beta were found to be inhibited by styraxoside A in a concentration-dependent manner. Furthermore, styraxoside A inhibited the LPS-induced DNA binding activity of nuclear factor-kappaB (NF-kappaB). Taken together, our data indicate that styraxoside A inhibits LPS-induced iNOS, COX-2, TNF-alpha, and IL-1beta expressions through the down-regulation of NF-kappaB-DNA binding activity.     

Inhibitory effect of trimidox on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages

We examined the effect of trimidox (3,4,5-trihydroxybenzamidoxime) on the production of nitric oxide (NO) by lipopolysaccharide (LPS) in mouse RAW 264.7 macrophages. Trimidox (50 - 300 microM) concentration-dependently inhibited NO production by LPS (0.01, 0.1, or 1 microg/ml) after incubation for 24 h. LPS-induced expression of inducible NO synthase (iNOS) and degradation of IkappaBalpha were prevented by trimidox. The protective effect against NO production by LPS was not only observed in prior incubation but also later incubation with trimidox until iNOS was activated by LPS. These results suggest that trimidox has a predominantly protective effect against LPS-induced production of NO via iNOS expression.     

Pentoxifylline potentiates nitric oxide production in interleukin-1beta-stimulated vascular smooth muscle cells through cyclic AMP-dependent protein kinase A pathway

In the present study, we observed that pentoxifylline (PTX) significantly augmented the nitric oxide (NO) production and the iNOS gene expression by interleukin-1beta (IL-1beta)-stimulated vascular smooth muscle cells (VSMCs). The enhancing effects of PTX on the IL-1beta-induced NO production was associated with an increased intracellular cyclic AMP (cAMP) levels, and the synergistic effects of PTX on the IL-1beta-induced NO production was blocked by cAMP-dependent protein kinase A (PKA) inhibitors. PKA inhibitors, KT5720 and H89, markedly decreased the augmented expression of iNOS gene whereas ODQ, a soluble guanylate cyclase inhibitor, did not affect the enhancing effect. In addition, the pretreatment with KT5720 or H89 abolished the increased translocation of the p65 subunit of NF-kappaB into the nucleus by PTX in the IL-1beta-stimulated VSMCs. These results suggest that enhancing effects of PTX on the iNOS gene expression in the IL-1beta-stimulated VSMCs is mediated predominantly through the activation of NF-kappaB via cAMP-dependent PKA pathway.     

Brazilein protects the brain against focal cerebral ischemia reperfusion injury correlating to inflammatory response suppression

Brazilein isolated from Caesalpinia sappan was evaluated for neuroprotection against transient focal cerebral ischemia/reperfusion in rats. The results showed that administration of brazilein after the onset of cerebral ischemia reperfusion can reduce the brain infarction area and improve the neurological score. The mechanisms underlying the action were investigated and attributed to the anti-inflammatory effect of brazilein, because a decrease of the mRNA level of pro-inflammatory cytokines (tumor necrosis factor-alpha(TNF-alpha) and interleukin-6 (IL-6)) was found in the ischemic animals with brazilein treatment. To further substantiate the anti-inflammatory effect of brazilein, we examined the mRNA expression of the cytokines in the lipopolysaccharide (LPS) induced microglial cell line BV2 cells; TNF-alpha and IL-6 mRNA expressions were significantly suppressed by brazilein treatment but the decrease of interleukin-1beta (IL-1beta) expression was not detected. Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS), another indicator of the inflammatory response of the immune cells was measured in RAW 264.7 macrophages and BV2 cells; brazilein inhibited its production induced by LPS in both types of cells in a dose-dependent manner. Consistently, the mRNA level of iNOS was also decreased by brazilein. Together, these results illustrate that brazilein can protect the brain against ischemia/reperfusion injury and the anti-inflammatory effect was believed to be one of the contributive mechanisms.     

Inhibition of inducible nitric oxide synthase gene expression and nitric oxide synthesis in vascular smooth muscle cells by granulocyte-colony stimulating factor in vitro.

Clinical and experimental evidence suggests that granulocyte-colony stimulating factor (G-CSF) acts as an anti-inflammatory modulator with beneficial effects in severe inflammatory diseases, e.g., sepsis and septic shock. Excessive production of nitric oxide (NO) is regarded as a potent mediator of the vascular changes leading to systemic hypotension that occurs during sepsis. Therefore, the aim of the present study was to investigate the influence of G-CSF on inducible nitric oxide synthase (iNOS) gene expression and NO synthesis in vascular smooth muscle cells (VSMC). Qualitative and quantitative analyses of iNOS cDNA revealed that G-CSF significantly reduced interferon-gamma/lipopolysaccharide (IFN-gamma/LPS) dependent iNOS gene expression (P < 0.05) following 6, 18, 24, and 48 h incubation periods. In addition, the co-application of G-CSF resulted in a decreased IFN-gamma/LPS mediated iNOS protein generation as detected by immunoblotting methods after 24 and 48 h. Measurement of the stable NO metabolites showed a significant reduction of nitrite/nitrate concentrations following co-incubation of VSMC with G-CSF + IFN-gamma/LPS (242.57 +/- 10.73 nmol NO2-/NO3-/mg cell protein, n = 8) as compared to IFN-gamma/LPS treatment (306.20 +/- 19.26 nmol NO2-/NO3-/mg cell protein, n = 8, P < 0.05) following a 24-h incubation protocol. This inhibitory effect of G-CSF was still present after a 48 h incubation period (G-CSF + IFN-gamma/LPS: 319.56 +/- 6.26 nmol NO2-/NO3-/mg cell protein; IFN-gamma/LPS: 489.20 +/- 27.15 nmol NO2-/NO3-/mg cell protein (P < 0.05), n = 8, respectively). The present findings suggest that inhibition of iNOS gene expression and NO generation in VSMC might be one of the protective anti-inflammatory effects of G-CSF during sepsis.     

Inhibition of nitric oxide and tumor necrosis factor-alpha (TNF-alpha) production by propenone compound through blockade of nuclear factor (NF)-kappa B activation in cultured murine macrophages

Lipopolysaccharide (LPS)-stimulated macrophages produce large amounts of nitric oxide (NO) by inducible nitric oxide synthase (iNOS). This is an important mechanism in macrophage-induced septic shock and inflammation. In the present study, we tested a synthetic propenone compound, 1-furan-2-yl-3-pyridin-2-yl-propenone (FPP-3) for its ability to inhibit the production of tumor necrosis factor-alpha (TNF-alpha) and an inducible enzyme, iNOS, in the LPS-stimulated murine macrophage-like cell line, RAW264.7. FPP-3 consistently inhibited nitric oxide (NO) and TNF-alpha production in a dose dependent manner, with IC(50) values of 10.0 and 13.1 microM, respectively. Western blotting probed with specific anti-iNOS antibodies showed that the decrease in quantity of the NO product was accompanied by a decrease in the iNOS protein level. In cells transiently transfected with nuclear factor (NF)-kappaB promoter-luciferase reporter construct, this compound clearly inhibited the LPS-stimulated NF-kappaB activation. Moreover, this compound inhibited IkappaB-alpha degradation in a concentration and time-dependent manner. These results indicate that FPP-3 inhibits NO production via inhibition of degradation of IkappaB-alpha through NF-kappaB activation.