Arctigenin inhibits lipopolysaccharide-induced iNOS expression in RAW264.7 cells through suppressing JAK-STAT signal pathway

Arctigenin has been demonstrated to have an anti-inflammatory function, but the precise mechanisms of its action remain to be fully defined. In the present study, we determined the effects of arctigenin on lipopolysaccharide (LPS)-induced production of proinflammatory mediators and the underlying mechanisms involved in RAW264.7 cells. Our results indicated that arctigenin exerted its anti-inflammatory effect by inhibiting ROS-dependent STAT signaling through its antioxidant activity. Arctigenin also significantly reduced the phosphorylation of STAT1 and STAT 3 as well as JAK2 in LPS-stimulated RAW264.7 cells. The inhibitions of STAT1 and STAT 3 by arctigenin prevented their translocation to the nucleus and consequently inhibited expression of iNOS, thereby suppressing the expression of inflammation-associated genes, such as IL-1β, IL-6 and MCP-1, whose promoters contain STAT-binding elements. However, COX-2 expression was slightly inhibited at higher drug concentrations (50 μM). Our data demonstrate that arctigenin inhibits iNOS expression via suppressing JAK-STAT signaling pathway in macrophages.     

GYF-17, a chloride substituted 2-(2-phenethyl)-chromone,suppresses LPS-induced inflammatory mediator production in RAW264.7 cells by inhibiting STAT1/3 and ERK1/2 signaling pathways

GYF-17, a 2-(2-phenethyl)-chromone derivative, was isolated from agarwood and showed superior activity of inhibiting NO production of RAW264.7 cells induced by LPS in our preliminary pharmacodynamic screening. In order to develop novel therapeutic drug for acute and chronic inflammatory disorders, the anti-inflammatory activity and underlying mechanism of GYF-17 were investigated in LPS-induced RAW264.7 cells. The results showed that GYF-17 could reduce LPS-induced expression of iNOS and then result in the decrement of NO production. More meaningful, the expression and secretion of key pro-inflammatory factors, including TNF-α, IL-6 and IL-1β, were intensively inhibited by GYF-17. Furthermore, GYF-17 also down regulated the expression of COX2 and the production of PGE2 which plays important role in causing algesthesia during inflammatory response. In mechanism study, GYF-17 selectively suppressed phosphorylation of STAT1/3 and ERK1/2 during the activation of NF-κB, MAPK and STAT signaling pathways induced by LPS. Collectively, GYF-17 can intensively suppress the production of LPS-induced inflammatory mediators in RAW264.7 cells by inhibiting STAT1/3 and ERK1/2 signaling pathways and thereby shows great potential to be developed into therapeutic drug for inflammatory diseases.     

Lycorine inhibits lipopolysaccharide-induced iNOS and COX-2 up-regulation in RAW264.7 cells through suppressing P38 and STATs activation and increases the survival rate of mice after LPS challenge

As a natural alkaloid extracted from Amaryllidaceae, lycorine shows various biological effects on tumor cells. Here we show that lycorine dose-dependently inhibited the LPS-induced up-regulation of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein level in RAW264.7 cells. Besides, it also inhibited NO, PGE(2), TNF-α and IL-6 release from LPS-treated RAW264.7 cells. RT-PCR experiments showed that lycorine suppressed LPS-induced iNOS but not COX-2 gene expression. Moreover, lycorine decreased LPS-induced mortality in mice. Mechanistically, LPS-induced activation of P38 and STATs pathways was suppressed significantly by lycorine. In addition, lycorine did not interfere with the phosphorylation of ERK1/2, JNK1/2 and NF-κB pathways. In conclusion, lycorine inhibits LPS-induced production of pro-inflammatory mediators and increases the survival rate of mice after LPS challenge, suggesting that lycorine could play an anti-inflammatory role in response to LPS.     

Ampelopsin attenuates lipopolysaccharide-induced inflammatory response through the inhibition of the NF-κB and JAK2/STAT3 signaling pathways in microglia

Increasing evidence suggests that microglia are a major cellular contributor to neuroinflammation. The present study investigated whether Ampelopsin (Amp), a type of flavanonol derivative from Ampelopsis grossedentata, may exert an anti-inflammatory effect on lipopolysaccharide (LPS)-induced BV2 and primary microglia cells. We found that pre-treatment of microglia cells with Amp before LPS with a non-cytotoxic concentration range decreased the production of nitric oxide (NO) and prostaglandin E2 (PGE2). Amp also suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the mRNA and protein levels. In addition, LPS-induced production of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) was obviously reduced by Amp. Our mechanistic study indicated that Amp suppressed LPS-induced activation of the IκB/NF-κB inflammation pathway without affecting changes in the phosphorylation levels of mitogen-activated protein kinases (MAPKs) in BV2 cells. Further studies revealed that Amp markedly reduced the phosphorylation levels of JAK2-STAT3 and STAT3 nuclear translocation. Overall, our data suggest that Amp can suppress the LPS-induced inflammatory response of microglial cells, indicating that Amp has potential for the treatment of inflammation-mediated neurodegenerative diseases.     

蟛蜞菊内酯对脂多糖诱导RAW264.7细胞环氧化酶2、NO及TNF-α的影响

目的:研究蟛蜞菊内酯对脂多糖(lipopo-lysaccharide,LPS)诱导RAW264.7巨噬细胞环氧化酶2(COX-2)、NO及TNF-α的作用。方法:ELISA方法检测0.2、2、20μmol/L不同浓度蟛蜞菊内酯对终浓度为10μg/mL LPS诱导RAW264.7细胞产生TNF-α、NO及前列腺素E2(PGE2)的影响,Western blot方法检测蟛蜞菊内酯对LPS诱导COX-2酶蛋白表达的影响。结果:LPS能够明显诱导小鼠RAW264.7细胞产生的COX-2酶蛋白,蟛蜞菊内酯低中高3个浓度均能抑制LPS诱导产生的COX-2酶蛋白表达。PGE2可以被LPS诱导增加,与空白组比有显著差异。蟛蜞菊内酯低中高3个浓度均能抑制LPS诱导产生的PGE2、NO和TNF-α,呈现剂量依赖性。结论:蟛蜞菊内酯抗炎的作用机制可能为抑制COX-2的蛋白表达,进而抑制PGE2的生成,也可能与抑制NO和TNF-α生成有关。     

Saikosaponin a and its epimer saikosaponin d exhibit anti-inflammatory activity by suppressing activation of NF-κB signaling pathway

Saikosaponin a (SSa) and its epimer saikosaponin d (SSd) are major triterpenoid saponin derivatives from Radix bupleuri (RB), which has been long used in Chinese traditional medicine for treatment of various inflammation-related diseases. In the present study, the anti-inflammatory activity, as well as the underlying mechanism, of SSa and SSd was investigated in lipopolysaccharide (LPS)-induced RAW264.7 cells. Our results demonstrated that both SSa and SSd significantly inhibited the expression of inducible nitric-oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-induced RAW264.7 cells, and finally resulted in the reduction of nitric oxide (NO) and prostaglandin E(2) (PGE(2)). In addition, LPS-induced production of major pro-inflammatory cytokines: the tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), was suppressed in a dose-dependent manner by the treatment of SSa or SSd in RAW264.7 cells. Further analysis revealed that both SSa and SSd could inhibit translocation of nuclear factor-κB (NF-κB) from the cytoplasm to the nucleus in the LPS-induced RAW264.7 cells. Furthermore, SSa and SSd exhibited significant anti-inflammatory activity in two different murine models of acute inflammation, carrageenan-induced paw edema in rats and acetic acid-induced vascular permeability in mice. In conclusion, SSa and SSd showed potent anti-inflammatory activity through inhibitory effects on NF-κB activation and thereby on iNOS, COX-2 and pro-inflammatory cytokines.     

Tormentic acid, a triterpenoid saponin, isolated from Rosa rugosa, inhibited LPS-induced iNOS, COX-2, and TNF-α expression through inactivation of the nuclear factor-κb pathway in RAW 264.7 macrophages

We previously reported that extract of Rosa rugosa root and its active triterpenoids constituents exhibit anti-nociceptive and anti-inflammatory effects in animal models. However, little is known about the effects and the molecular mechanism of the 19α-hydroxyursane-type triterpenoids. Among the tested 19α-hydroxyursane-type triterpenoids (kaji-ichigoside F(1), rosamultin, euscaphic acid, tormentic acid (TA)), TA was found to most potently inhibit the production of nitric oxide (NO) in RAW 264.7 cells. We investigated the anti-inflammatory effects and its underlying molecular mechanisms of TA in lipopolysaccaride (LPS)-stimulated RAW 264.7 cells. TA dose-dependently reduced the productions of NO, prostaglandin E(2) (PGE(2)), and tumor necrosis factor-α (TNF-α) induced by LPS. In addition, TA significantly suppressed the LPS-induced expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α at the mRNA and protein levels. Moreover, treatment with TA decreased LPS-induced DNA binding of nuclear factor-kappa B (NF-κB) and nuclear translocation of p65 and p50 subunits of NF-κB. Consistent with these findings, TA also suppressed the LPS-stimulated degradation and phosphorylation of inhibitor of kappa B-α (IκB-α). Taken together, these results suggest that the anti-inflammatory activity of TA is associated with the down-regulation of iNOS, COX-2, and TNF-α through the negative regulation of the NF-κB pathway in RAW 264.7 cells.     

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.     

Inhibition of LPS-induced NO and PGE2 production by asiatic acid via NF-kappa B inactivation in RAW 264.7 macrophages: possible involvement of the IKK and MAPK pathways

In the present study, we investigated the effect of asiatic acid (the aglycon of asiaticoside) and asiaticoside isolated from the leaves of Centella asiatica (Umbelliferae) on LPS-induced NO and PGE(2) production in RAW 264.7 macrophage cells. Asiatic acid more potently inhibited LPS-induced NO and PGE(2) production than asiaticoside. Consistent with these observations, the protein and mRNA expression levels of inducible iNOS and COX-2 enzymes were inhibited by asiatic acid in a concentration-dependent manner. In addition, asiatic acid dose-dependently reduced the production of IL-6, IL-1 beta and TNF-alpha in LPS-stimulated RAW 264.7 macrophage cells. Furthermore, asiatic acid inhibited the NF-kappaB activation induced by LPS, and this was associated with the abrogation of I kappa B-alpha degradation and with subsequent decreases in nuclear p65 and p50 protein levels. Moreover, the phosphorylations of IKK, p38, ERK1/2, and JNK in LPS-stimulated RAW 264.7 cells were suppressed by asiatic acid in a dose-dependent manner. These results suggest that the anti-inflammatory properties of asiatic acid might be the results from the inhibition of iNOS, COX-2, IL-6, IL-1 beta, and TNF-alpha expressions through the down-regulation of NF-kappaB activation via suppression of IKK and MAP kinase (p38, ERK1/2, and JNK) phosphorylation in RAW 264.7 cells.     

白木香叶提取物对LPS诱导RAW264.7巨噬细胞炎症因子的影响

目的 采用LPS刺激巨噬细胞RAW264.7,建立体外的炎症模型,探讨白木香叶提取物抗炎活性和作用机制.方法 采用MTT法检测白木香叶提取物( ASPE)对RAW264.7细胞的毒性作用;采用ELISA法检测ASPE对IL-6表达情况;采用Western blotting检测iNOS和COX-2蛋白表达情况,结果 ASPE能抑制LPS刺激RAW264.7所产生的炎症反应,其作用机制可能与其抑制iNOS和COX-2蛋白表达有关.结论 白木香叶提取物有抗炎活性.     

染料木素通过TIPE 2负性调控Akt活性促进脂多糖活化的巨噬细胞凋亡

目的探究染料木素(genistein,GEN)对脂多糖(lipopolysaccharide,LPS)活化的RAW264.7细胞凋亡的影响及其可能的药理学作用机制。方法GEN预孵育RAW264.7细胞或慢病毒介导的肿瘤坏死因子α诱导蛋白8样分子2(tumor necrosis factor-α-induced protein 8-like 2,TIPE 2)过表达细胞2 h,再与LPS共孵育24 h,采用CCK 8试剂盒检测细胞活力,Annexin V-FITC/PI试剂盒检测细胞凋亡水平,qRT-PCR检测TNF-α、IL-6、caspase-8、caspase-3和TIPE 2 mRNA,Western blot检测iNOS、COX-2、caspase-8、caspase-3、TIPE 2、Akt和p-Akt蛋白表达。结果LPS促进RAW264.7细胞TNF-α、IL-6、iNOS、COX-2合成;GEN抑制LPS活化的RAW264.7细胞活力,凋亡细胞增多,并上调caspase-8、caspase-3、TIPE 2 mRNA及蛋白表达;TIPE 2过表达上调活化RAW264.7细胞caspase-8、caspase-3 mRNA及蛋白表达,减少Akt磷酸化,且与GEN具有协同作用。结论GEN可能通过上调TIPE 2抑制Akt活性,激活外源性凋亡途径,促进LPS活化的RAW264.7细胞凋亡。     

Wogonin, baicalin, and baicalein inhibition of inducible nitric oxide synthase and cyclooxygenase-2 gene expressions induced by nitric oxide synthase inhibitors and lipopolysaccharide

We previously reported that oroxylin A, a polyphenolic compound, was a potent inhibitor of lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In the present study, three oroxylin A structurally related polyphenols isolated from the Chinese herb Huang Qui, namely baicalin, baicalein, and wogonin, were examined for their effects on LPS-induced nitric oxide (NO) production and iNOS and COX-2 gene expressions in RAW 264.7 macrophages. The results indicated that these three polyphenolic compounds inhibited LPS-induced NO production in a concentration-dependent manner without a notable cytotoxic effect on these cells. The decrease in NO production was in parallel with the inhibition by these polyphenolic compounds of LPS-induced iNOS gene expression. However, these three compounds did not directly affect iNOS enzyme activity. In addition, wogonin, but not baicalin or baicalein, inhibited LPS-induced prostaglandin E2 (PGE2) production and COX-2 gene expression without affecting COX-2 enzyme activity. Furthermore, N-nitro-L-arginine (NLA) and N-nitro-L-arginine methyl ester (L-NAME) pretreatment enhanced LPS-induced iNOS (but not COX-2) protein expression, which was inhibited by these three polyphenolic compounds. Wogonin, but not baicalin or baicalein, similarly inhibited PGE2 production and COX-2 protein expression in NLA/LPS or L-NAME/LPS-co-treated RAW 264.7 cells. These results indicated that co-treatment with NOS inhibitors and polyphenolic compounds such as wogonin effectively blocks acute production of NO and, at the same time, inhibits expression of iNOS and COX-2 genes.     

Inducible nitric oxide synthase inhibitors of Chinese herbs III. Rheum palmatum

In this paper, the effects of bioactive compounds of Rheum palmatum L. on the inhibition of NO production from RAW 264.7 cells were explored. Seven main anthraquinone derivatives were isolated from the root of R. palmatum, and of these, emodin and rhein significantly inhibited nitrite production from lipopolysaccharide (LPS)-activated RAW 264.7 cells. The IC(50) values for inhibition of nitrite production by emodin and rhein were 60.7 and 67.3 microM, respectively. After iNOS enzyme activity was stimulated by LPS for 12 h, treatment with emodin or rhein at 20 microg/ml for 18 h did not significantly inhibit NO production. The data show that the inhibitory activity of emodin and rhein is not due to direct inhibition of iNOS enzyme activity. However, expression of iNOS and the COX-2 protein was inhibited by emodin in LPS-activated RAW 264.7 cells, and PGE(2) production was reduced. Rhein also inhibited LPS-induced iNOS protein expression, but not COX-2 or PGE(2) production. On the other hand, inhibition effects on NO production from RAW 264.7 cells were enhanced and cytotoxic effects decreased by co-treatment with emodin and rhein. In conclusion, emodin and rhein are major iNOS inhibitors of R. palmatum and may possibly serve as bioactive substances for anti-inflammation effects.     

Polygonum cuspidatum, compared with baicalin and berberine, inhibits inducible nitric oxide synthase and cyclooxygenase-2 gene expressions in RAW 264.7 macrophages

Polygonum cuspidatum water extract (PCWE) was shown to be a potent inhibitor of lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). PCWE was compared to baicalin isolated from Scutellaria baicalensis Georgi and berberine of Coptidis rhizoma and Phellodendri cortex, for their effects on LPS-induced nitric oxide (NO) production and iNOS and COX-2 gene expressions in RAW 264.7 macrophages. Both PCWE and the compounds inhibited LPS-induced NO production in a concentration-dependent manner without a cytotoxicity. The decrease in NO production was in parallel with the inhibition of LPS-induced iNOS gene expression by PCWE and the compounds. In contrast, iNOS enzyme activity was not inhibited by PCWE and two agents. In addition, only PCWE inhibited LPS-induced prostaglandin E2 (PGE2) production and COX-2 gene expression without affecting COX-2 enzyme activity, while baicalin or berberine did not. Furthermore, N-nitro-L-arginine (NLA) and N-nitro-L-arginine methyl ester (L-NAME) pretreatment enhanced LPS-induced iNOS protein expression, which was inhibited by these PCWE and two agents, although LPS-induced COX-2 protein expression was not affected by NLA and L-NAME. PCWE inhibited PGE2 production and COX-2 protein expression in NLA/LPS or L-NAME/LPS-co-treated RAW 264.7 cell, however, baicalin or berberine did not. From the results, it was concluded that co-treatment with NOS inhibitors and PCWE effectively blocks acute production of NO and inhibits expression of iNOS and COX-2 genes.