Sauchinone suppresses pro-inflammatory mediators by inducing heme oxygenase-1 in RAW264.7 macrophages

Sauchinone, a biologically active lignan isolated from the roots of Saururus chinensis (LOUR.) BAILL. (Saururaceae), is reported to exert a variety of biological activities, such as hepatoprotective, anti-inflammatory actions and inhibitory effects on bone resorption. In this study, we investigated the effect of sauchinone in suppressing cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, leading to a reduction in COX-2-derived prostaglandin E(2) (PGE(2)) and iNOS-derived nitric oxide (NO) production in lipopolysaccharide (LPS) stimulated RAW264.7 macrophages. Present study also demonstrates the effects of sauchinone in inducing heme oxygenase-1 (HO-1) expression and an increase in heme oxygenase (HO) activity in RAW264.7 macrophages. The effects of sauchinone on LPS-induced PGE(2), NO, tumor necrosis factor-α (TNF-α) and interlukine-1β (IL-1β) production were partially reversed by the HO-1 inhibitor Tin protoporphyrin was also seen in this study. In addition, we found that treatment with extracellular signal-regulated kinase (ERK) inhibitor (PD98059) reduced sauchinone-induced HO-1 expression. Sauchinone also increased ERK phosphorylation. These results suggest that sauchinone inhibits pro-inflammatory mediators through expression of anti-inflammatory HO-1 via ERK pathway.     

Prenylated isoflavones from Cudrania tricuspidata inhibit NO production in RAW 264.7 macrophages and suppress HL-60 cells proliferation

Inhibitory effects of NO production in RAW 264.7 macrophages guided the isolation of nine prenylated isoflavones, including a new cudraisoflavone L (1) and eight known metabolites furowanin B (2), erysubin A (3), wighteone (4), lupalbigenin (5), laburnetin (6), isolupalbigenin (7), 6,8-diprenylorobol (8), millewanin H (9) from the leaves of Cudrania tricuspidata. At the concentration of 10 μM, compounds 1, 2, and 4 significantly inhibited NO production with the inhibitory values of 72.5 ± 2.4, 66.9 ± 1.8, and 55.4 ± 2.7%, respectively. In addition, all of isolated compounds 1–9 showed promising cytotoxic effects toward HL-60 cells (IC₅₀ 4.3 ± 0.7 to 18.0 ± 1.7 μM).     

Ethyl linoleate from garlic attenuates lipopolysaccharide-induced pro-inflammatory cytokine production by inducing heme oxygenase-1 in RAW264.7 cells

In the present study, an essential fatty acid, ethyl linoleate (ELA), was isolated from the cloves of Allium sativum, and its structure was elucidated by NMR and GC-MS analyses. In vitro systems were used to evaluate the anti-inflammatory activity of ELA. Our results indicate that ELA down-regulates inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and thereby reduces nitric oxide (NO) and prostaglandin E₂ production in lipopolysaccharide (LPS)-activated RAW 264.7 cells. Immunofluorescent microscopy and western blot analyses revealed that these effects were mediated by impaired translocation of nuclear factor (NF)-κB and inhibition of phosphorylation of mitogen activated protein kinases. Furthermore, ELA exerted its anti-inflammatory activity by inducing heme oxygenase-1 (HO-1) expression, as determined by HO-1 small interfering (Si) RNA system. Si RNA-mediated knock-down of HO-1 abrogated the inhibitory effects of ELA on the production of NO, TNF-α, IL-1β, and IL-6 in LPS-induced macrophages. These findings indicate the potential therapeutic use of ELA as an anti-inflammatory agent.     

Inhibition of lipopolysaccharide-induced nitric oxide production by flavonoids in RAW264.7 macrophages involves heme oxygenase-1

The role of heme oxygenase-1 (HO-1) played in the inhibitory mechanism of flavonoids in lipopolysaccharide (LPS)-induced responses remained unresolved. In the present study, flavonoids, including 3-OH flavone, baicalein, kaempferol, and quercetin, induced HO-1 gene expression at the protein and mRNA levels in the presence or absence of LPS in RAW264.7 macrophages. This effect was associated with suppression of LPS-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) protein expression. Hemin induced HO-1 protein expression and this was associated with the suppression of LPS-induced NO production and iNOS protein expression in a dose-dependent manner. In addition, an increase in bilirubin production was found in flavonoid- and hemin-treated cells. Hemin, at the doses of 10, 20, and 50 microM, dose-dependently stimulated the flavonoid (50 microM)-induced HO-1 protein expression, and enhanced their inhibitory effects on LPS-induced NO production and iNOS protein expression. Pretreatment of the HO-1 inhibitor, tin protoporphyrin (10 microM), attenuated the inhibitory activities of the indicated flavonoids on LPS-induced NO production. Morphologic analysis showed that 3-OH flavone, baicalein, kaempferol, quercetin, hemin, and tin protoporphyrin did not cause any change in cell viability in the presence or absence of LPS. In contrast, only 3-OH flavone showed a significant inhibition of cell growth using the MTT assay. Transfection of an HO-1 vector in macrophages (HO-1/RAW264.7) resulted in a 3-fold increase in HO-1 protein compared with that the parental RAW264.7 cells. NO production mediated by LPS in HO-1 over-expressed RAW264.7 cells (HO-1/RAW264.7) was significant less than that in parental RAW264.7 cells. 3-OH Flavone, baicalein, kaempferol, and quercetin showed a more significant inhibition on LPS-induced NO production in HO-1/RAW264.7 cells than in parental RAW264.7 cells. These results provide evidence on the role of HO-1 in the inhibition of LPS-induced NO production by flavonoids. A combination of HO-1 inducers (i.e. hemin) and flavonoids might be an effective strategy for the suppression of LPS-induced NO production.     

Inhibitory effect of ethyl acetate fraction from Cudrania tricuspidata on the expression of nitric oxide synthase gene in RAW 264.7 macrophages stimulated with interferon-gamma and lipopolysaccharide.

It was found that the production of nitric oxide (NO) by RAW 264.7 macrophages stimulated with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) could be markedly inhibited by the ethyl-acetate-soluble fraction of 80% aqueous methanolic extract of stem barks of Cudrania tricuspidata (EACT). Inhibition of NO production was achieved by reducing inducible nitric oxide synthase (iNOS) expression at protein and mRNA levels and by inactivating nuclear factor-kappa B (NF-kappa B), but not by inhibiting iNOS activity. Thus, further phytochemical and pharmacological studies may lead to isolation and structural identification of an inhibitor of iNOS from C. tricuspidata, which has been used as a traditional medicine for curing inflammation.     

Cornuside suppresses lipopolysaccharide-induced inflammatory mediators by inhibiting nuclear factor-kappa B activation in RAW 264.7 macrophages

Cornuside, a secoiridoid glucoside compound, was isolated from the fruit of Cornus officinalis SIEB. et ZUCC. Cornuside has been reported to possess immunomodulatory and anti-inflammatory activities. However, the effects and mechanism of action of cornuside in inflammation have not been fully characterized. The present study was therefore designed to examine whether cornuside suppresses inflammatory response in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Cornuside significantly inhibited the LPS-induced production of nitric oxide, prostaglandin E(2), tumor necrosis factor-alpha, interleukin-6 (IL-6), and IL-1beta. The mRNA and protein expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were also decreased by cornuside. Furthermore, cornuside significantly attenuated the LPS-stimulated phosphorylation and degradation of inhibitory kappa B-alpha and the subsequent translocation of the p65 subunit of nuclear factor-kappa B (NF-κB) to the nucleus. Cornuside also reduced the phosphorylations of extracellular-signal-related kinase (ERK1/2), p38, and c-Jun N-terminal kinase (JNK1/2). These results suggest that the anti-inflammatory property of cornuside is related to the downregulations of iNOS and COX-2 due to NF-κB inhibition as well as the negative regulation of ERK1/2, p38, and JNK1/2 phosphorylations in RAW 264.7 cells.     

Myrrh mediates haem oxygenase-1 expression to suppress the lipopolysaccharide-induced inflammatory response in RAW264.7 macrophages

Objectives To elucidate a novel anti‐inflammatory mechanism of myrrh against lipopolysaccharide (LPS)‐induced inflammation. Methods RAW264.7 macrophages were cultured in DMEM and then cells were treated with LPS or LPS plus a myrrh methanol extract (MME) for 24 h. The culture medium was collected for determination of nitric oxide (NO), prostaglandin (PG)E₂, interleukin (IL)‐1β, and tumour necrosis factor (TNF)‐α, and cells were harvested by lysis buffer for Western blot analysis. Key findings Our data showed that treatment with the MME (1～100 µg/ml) did not cause cytotoxicity or activate haem oxygenase‐1 (HO‐1) protein synthesis in RAW264.7 macrophages. Furthermore, the MME inhibited LPS‐stimulated NO, PGE₂, IL‐1β and TNF‐α release and inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)‐2 protein expression. Zn(II) protoporphyrin IX, a specific inhibitor of HO‐1, blocked the inhibition of iNOS and COX‐2 expression by the MME. Conclusions These results suggest that among mechanisms of the anti‐inflammatory response, the MME inhibited the production of NO, PGE₂, IL‐1β and TNF‐α by downregulating iNOS and COX‐2 gene expression in macrophages and worked through the action of HO‐1.     

Asperlin from the marine-derived fungus Aspergillus sp. SF-5044 exerts anti-inflammatory effects through heme oxygenase-1 expression in murine macrophages

Asperlin is a fungal metabolite isolated from Aspergillus sp. SF-5044. In the present study, we isolated asperlin from the marine-derived fungus Aspergillus sp. SF-5044 and demonstrated that it inhibited inducible nitric oxide synthase (iNOS) expression, reduced iNOS-derived NO, suppressed cyclooxygenase (COX)-2 expression, and reduced COX-derived prostaglandin (PG) E? production in lipopolysaccharide (LPS)-stimulated RAW264.7 and murine peritoneal macrophages. Similarly, asperlin reduced the production of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. In addition, asperlin inhibited the phosphorylation and degradation of IκB-α, as well as the nuclear translocation of p65 caused by the stimulation of LPS in RAW264.7 macrophages. Furthermore, asperlin induced heme oxygenase (HO)-1 expression through nuclear translocation of nuclear factor E2-related factor 2 and increased HO activity in RAW264.7 macrophages. The effects of asperlin on the LPS-induced expression of iNOS and COX-2 and production of NO, PGE?, TNF-α, and IL-1β were partially reversed by a HO-1 inhibitor, tin protoporphyrin. These findings suggest that asperlin-induced HO-1 expression plays a role in the anti-inflammatory effects of asperlin in macrophages.     

Chromene suppresses the activation of inflammatory mediators in lipopolysaccharide-stimulated RAW 264.7 cells

Inflammation is complex process involving a variety of immune cells that defend the body from harmful stimuli. However, pro-inflammatory cytokines and inflammatory mediators can also exacerbate diseases such as cancer. The aim of this study was to identify a natural effective remedy for inflammation. We isolated a functional algal chromene compound from Sargassum siliquastrum, named sargachromanol D (SD). We evaluated the anti-inflammatory effect of SD on lipopolysaccharide (LPS)-exposed RAW 264.7 cells by measuring cell viability, cytotoxicity, and production of inflammatory mediators such as nitric oxide (NO), prostaglandin E₂ (PGE₂), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. SD inhibited production of NO and PGE₂ from LPS-induced cells by preventing the expression of inflammatory mediators such as iNOS and COX-2 in a dose-dependent manner. Concurrently, levels of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 were reduced with increasing concentrations of SD. In addition, SD inhibited the activation of NF-κB and mitogen-activated protein kinases (MAPKs) pathways in a concentration-dependent manner. These results indicate that SD inhibits LPS-stimulated inflammation by inhibition of the NF-κB and MAPKs pathways in macrophages.     

Extract of Pinus densiflora needles suppresses acute inflammation by regulating inflammatory mediators in RAW264.7 macrophages and mice

ContextPinus densiflora Siebold & Zucc. (Pinaceae) needle extracts ameliorate oxidative stress, but research into their anti-inflammatory effects is limited.ObjectiveTo investigate antioxidant and anti-inflammatory effects of a Pinus densiflora needles (PINE) ethanol extract in vitro and in vivo.Materials and methodsWe measured levels of reactive oxygen species (ROS), superoxide dismutase (SOD) and inflammatory mediators in lipopolysaccharide (LPS)-stimulated RAW264.7 cells at various PINE concentrations (25, 50 and 100 μg/mL; but 6.25, 12.5 and 25 μg/mL for interleukin-1β and prostaglandin E₂ (PGE₂)). Thirty ICR mice were randomized to six groups: vehicle, control, PINE pre-treatment (0.1, 0.3 and 1 mg/left ear for 10 min followed by arachidonic acid treatment for 30 min) and dexamethasone. The posttreatment ear thickness and myeloperoxidase (MPO) activity were measured.ResultsPINE 100 μg/mL significantly decreased ROS (IC₅₀, 70.93 μg/mL, p < 0.01), SOD (IC₅₀, 30.99 μg/mL, p < 0.05), malondialdehyde (p < 0.01), nitric oxide (NO) (IC₅₀, 27.44 μg/mL, p < 0.01) and tumour necrosis factor-alpha (p < 0.05) levels. Interleukin-1β (p < 0.05) and PGE₂ (p < 0.01) release decreased significantly with 25 μg/mL PINE. PINE 1 mg/ear inhibited LPS-stimulated expression of cyclooxygenase-2 and inducible NO synthase in RAW264.7 macrophages and significantly inhibited ear oedema (36.73–15.04% compared to the control, p < 0.01) and MPO activity (167.94–105.59%, p < 0.05).Discussion and conclusionsPINE exerts antioxidant and anti-inflammatory effects by inhibiting the production of inflammatory mediators. Identified flavonoids such as taxifolin and quercetin glucoside can be attributed to effect of PINE.     

Cudratricusxanthone A protects mouse hippocampal cells against glutamate-induced neurotoxicity via the induction of heme oxygenase-1

Cudratricusxantone A (CTXA), isolated from the roots of Cudrania tricuspidata Bureau (Moraceae), has potent hepatoprotective, antiproliferative, and monoamine oxidase inhibitory effects. In this study, we examined whether CTXA could protect HT22-immortalized hippocampal cells against glutamate-induced oxidative stress through the induction of heme oxygenase (HO)-1 expression. CTXA induced the expression of HO-1 and increased HO activity dose- and time-dependently. CTXA also suppressed glutamate-induced ROS generation in HT22 cells. Interestingly, treatment of neuronal cells with CTXA enhanced cellular resistance to glutamate oxidative stress. The protective effect of CTXA was abrogated by tin protoporphyrin IX, an HO inhibitor. In addition, treatment with the HO-1 inducer, cobalt protoporphyrin IX, and bilirubin, one of the enzymatic products of HO-1, produced comparable protection. These results demonstrate that CTXA protects neuronal cells from glutamate-induced oxidative stress via the induction of HO-1.     

Biphasic induction of heme oxygenase-1 expression in macrophages stimulated with lipopolysaccharide

Time course relationship between inductions of iNOS and HO-1 was evaluated in RAW264.7 macrophages stimulated with LPS. Expression of HO-1 mRNA increased in a biphasic pattern, but that of xCT (cystine transporter) and iNOS mRNA increased in a monophasic manner. HO-1 protein level increased also in a biphasic manner, at 1-2 h and again between 8 and 24 h. However, iNOS protein began to increase at 4 h, quickly reaching a high level in a monophasic induction pattern. Production of NO* began to occur at 6 h and nitrite continued to accumulate in the culture medium. Total GSH level decreased markedly (50% of control) by 2 h, began to recover at 4 h, returned to control level by 6 h and increased above the control level during 10-24 h. Collectively, these results indicated that overproduced O2*- depletes GSH and triggers induction of xCT, HO-1, iNOS and HO-1 expression in sequence. Most notably, the second-phase induction of HO-1 was caused by overproduced NO*, resulting from LPS-derived iNOS induction. When this iNOS-derived delivery of NO* was combined with prior depletion of GSH using buthioninesulfoximine, an inhibitor of GSH biosynthesis, induction of HO-1 was potentiated. Furthermore, upon such super-induction of HO-1, NO* production was inhibited along with suppression of iNOS expression. Collectively, these results suggested that HO-1 is induced in a biphasic manner, sequentially by the overproduced O*2- and NO*, and the elevated HO-1 suppresses the production of these radicals in an auto-regulatory manner. This may allow the macrophages to survive from injuries that can be caused by concomitant oxidative and nitrosative stresses initiated by the LPS-driven oxidative burst.     

Cudratricusxanthone A isolated from the root bark of Cudrania tricuspidata inhibits the proliferation of vascular smooth muscle cells through the suppression of PDGF-receptor beta tyrosine kinase

Platelet derived growth factor (PDGF)-BB is one of the most potent vascular smooth muscle cell (VSMC) proliferative factors, and abnormal VSMC proliferation by PDGF-BB plays an important role in the development and progression of cardiovascular problems, including restenosis after coronary angioplasty and atherosclerosis. Previous phytochemical studies on the stems or root barks of Cudrania tricuspidata (Moraceae) resulted in the isolation of various isoprenylated xanthones and flavonoids, some of which have anti-cancer, hepatoprotective, anti-inflammatory and anti-oxidant activities. In the present study, we investigated the antiproliferative effect of cudratricusxanthone A isolated from the root bark of C. tricuspidata and its underlying mechanism in VSMCs. Antiproliferative effects of cudratricusxanthone A on VSMCs were examined by direct cell counting and [3H]-thymidine incorporation assays. Cudratricusxanthone A inhibited [3H]-thymidine incorporations into DNA in VSMCs that occurred in response to treatment with 50 ng/ml PDGF-BB. PDGF-BB-stimulated DNA synthesis was significantly reduced to 86.1, 80.2, 64.2 and 25.1% at concentrations of 0.1, 1, 2 and 3 microM, respectively. Moreover, pre-treatment with cudratricusxanthone A (0.1-3 microM) suppressed this PDGF-BB-stimulated cell number in a concentration-dependent manner. The inhibition percentages were 11.1, 22.7, 51.3 and 81.5% at the concentrations of 0.1, 1, 2 and 3 microM, respectively. We also investigated the mechanism of antiproliferative effects by cudratricusxanthone A in PDGF-BB-stimulated VSMCs. In Western blot analysis, 50 ng/ml PDGF-BB-stimulated phospholipase C (PLC)gamma1, Ras, and extracellular signal-regulated kinase1/2 (ERK1/2) phosphorylations were inhibited by cudratricusxanthone A (0.1-3 microM). Consisted with these findings, cudratricusxanthone A inhibited PDGF-receptor beta chain (PDGF-Rbeta) phosphorylation induced by PDGF-BB in a concentration-dependent manner. These findings suggest that the inhibitory effects of cudratricusxanthone A on DNA synthesis and proliferation by PDGF-BB-stimulated VSMCs are mediated by the suppressions of the PDGF-Rbeta and its downstream signaling pathways. Our observation may explain in part mechanistic basis for the prevention of cardiovascular diseases, such as atherosclerosis and restenosis after coronary angioplasty by cudratricusxanthone A.     

Evaluation of anti-inflammatory effect of fucoxanthin isolated from brown algae in lipopolysaccharide-stimulated RAW 264.7 macrophages

In this study, potential anti-inflammatory effect of fucoxanthin isolated from brown algae was assessed via inhibitory effect of nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 macrophage cells. The Myagropsis myagroides was selected for further experiments due to its profound NO inhibitory effect, and was partitioned with different organic solvents. Highest NO inhibitory effect was detected in the chloroform fraction, and the active compound was identified as fucoxanthin, a kind of carotenoid available in brown algae evidenced high correlation with the inhibitory effect of NO production (r² = 0.9511). Though, fucoxanthin significantly inhibited the NO production, it slightly reduced the prostaglandin E₂ (PGE₂) production. The inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) protein expressions were inhibited by fucoxanthin. Further, RT-PCR analysis indicated that the iNOS and COX-2 mRNA expressions were suppressed by fucoxanthin. Moreover, the release of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), and the mRNA expression levels of those cytokines were reduced by the addition of fucoxanthin in a dose-dependent manner. Hence, these results suggest that the use of fucoxanthin may be a useful therapeutic approach for the various inflammatory diseases.