Magnesium isoglycyrrhizinate suppresses LPS-induced inflammation and oxidative stress through inhibiting NF-κB and MAPK pathways in RAW264.7 cells

Magnesium Isoglycyrrhizinate (MgIG), a novel molecular compound extracted from licorice root, has exhibited greater anti-inflammatory activity and hepatic protection than glycyrrhizin and β-glycyrrhizic acid. In this study, we investigated the anti-inflammatory effect and the potential mechanism of MgIG on Lipopolysaccharide (LPS)-treated RAW264.7 cells. MgIG down-regulated LPS-induced pro-inflammatory mediators and enzymes in LPS-treated RAW264.7 cells, including TNF-α, IL-6, IL-1β, IL-8, NO and iNOS. The generation of reactive oxygen species (ROS) in LPS-treated RAW264.7 cells was also reduced. MgIG attenuated NF-κB translocation by inhibiting IKK phosphorylation and IκB-α degradation. Simultaneously, MgIG also inhibited LPS-induced activation of MAPKs, including p38, JNK and ERK1/2. Taken together, these results suggest that MgIG suppresses inflammation by blocking NF-κB and MAPK signaling pathways, and down-regulates ROS generation and inflammatory mediators.     

Synergistic anti-inflammatory effects of silibinin and thymol combination on LPS-induced RAW264.7 cells by inhibition of NF-κB and MAPK activation

BackgroundCombination drug therapy has become an effective strategy for inflammation control. The anti‑inflammatory capacities of silibinin and thymol have each been investigated on its own, but little is known about the synergistic anti-inflammatory effects of these two compounds.PurposeThis study aims to investigate the synergistic anti-inflammatory effects of silibinin and thymol when administered in combination to lipopolysaccharide (LPS)-induced RAW264.7 cells.MethodsRAW264.7 cells were pre-treated with silibinin and thymol individually or in combination for 2 h before LPS stimulation. Cell viability was detected by the MTT assay. Nitric oxide (NO) production was measured by Griess reagent. Reactive oxygen species (ROS) was evaluated by 2’,7’-dichlorofluorescein-diacetate. ELISA was used to detect tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6). Western blot was performed to analyse the protein expression of LPS-induced RAW264.7 cells.ResultsWe observed a synergistic anti-inflammatory effect of silibinin and thymol when administered in combination to LPS-induced RAW264.7 cells. Silibinin combined with thymol (40 μM and 120 μM respectively, with the molar ratio 1:3) had more potent effects on the inhibition of NO, TNF-α, and IL-6 than those exerted by individual administration of these compounds in LPS-induced RAW264.7 cells. The combination of silibinin and thymol (40 μM and 120 μM respectively, with the molar ratio 1:3) strongly inhibited ROS and cyclooxygenase-2 (COX-2). More importantly, the combination of silibinin and thymol (40 μM and 120 μM respectively, with the molar ratio 1:3) was also successful in inhibiting nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) activities. Our results suggest that the synergistic anti-inflammatory effects of silibinin with thymol were associated with the inhibition of NF-κB and MAPK signalling pathways.ConclusionThe combination of silibinin and thymol (40 μM and 120 μM, respectively, with the molar ratio 1:3) could inhibit inflammation by suppressing NF-κB and MAPK signalling pathways in LPS-induced RAW264.7 cells.     

Suppression of LPS-induced inflammatory and NF-κB responses by anomalin in RAW 264.7 macrophages

The treatment of inflammatory diseases today is largely based on interrupting the synthesis or action of the mediators that drive the host's response to injury. It is on the basis of this concept that most of the anti-inflammatory drugs have been developed. In our continuous search for novel anti-inflammatory agents from traditional medicinal plants, Saposhnikovia divaricata has been a focus of our investigations. Anomalin, a pyranocoumarin constituent of S. divaricata, exhibits potent anti-inflammatory activity. To clarify the cellular signaling mechanisms underlying the anti-inflammatory action of anomalin, we investigated the effect of anomalin on the production of inflammatory molecules in LPS-stimulated murine macrophages. The anomalin dose-dependently inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA and protein expression in LPS-stimulated RAW 264.7 macrophage. Molecular analysis using quantitative real time polymerase chain reaction (qRT-PCR) revealed that several pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were reduced by anomalin, and this reduction correlated with the down-regulation of the NF-κB signaling pathway. In addition, anomalin suppressed the LPS-induced phosphorylation and degradation of IκBα. To further study the mechanisms underlying its anti-inflammatory activity, an electrophoretic mobility shift assay (EMSA) using a (32) P-labeled NF-κB probe was conducted. LPS-induced NF-κB DNA binding was drastically abolished by anomalin. The present data suggest that anomalin is a major anti-inflammatory agent and may be a potential therapeutic candidate for the treatment of inflammatory disorders.     

Profiling signalling pathways of the receptor activator of NF-κB ligand-induced osteoclast formation in mouse monocyte cells,RAW264.7

Summary. Cell-based signal chemical genomics can profile the signalling pathway for certain cellular events by using a target-known chemical library. To ascertain its usefulness, the receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis in mouse monocyte/macrophage cells RAW264.7 was used as an in vitro experimental model. Of 180 target-known inhibitors/activators formatted in a 384-well plate, 8 chemicals were shown to inhibit the osteoclast formation, but 4 chemicals enhanced this process. A variety of references support, or possibly lead one to expect the effects of these 12 chemicals on the cellular process of osteoclastogenesis in RAW264.7 cells, but several signalling pathways were newly found in this study; for example, CA-074 Me inhibiting cathepsin B and nitrendipine blocking the calcium channel could have the potential to inhibit the osteoclast formation as well as bone resorption. This is a simple but very fast and powerful method of profiling the signalling pathway of certain cellular events. Signal chemical genomics could provide invaluable information for the exploration of new target signalling processes and further target-based drug discovery strategies. Authors’ address: Seong Hwan Kim, PhD, Laboratory of Chemical Genomics, Bio-Organic Science Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong-gu, Daejeon 305-600, Korea     

Selenium suppressed the LPS-induced inflammation of bovine endometrial epithelial cells through NF-κB and MAPK pathways under high cortisol background

The bovine uterus is susceptible to infection, and the elevated cortisol level due to stress are common in cows after delivery. The essential trace element selenium plays a pivotal role in the antioxidant and anti-inflammatory defence system of body. This study investigated whether selenium supplementation protected endometrial cells from inflammation in the presence of high-level cortisol. The primary bovine endometrial epithelial cells were subjected to Escherichia coli lipopolysaccharide to establish cellular inflammation model. The gene expression of inflammatory mediators and proinflammatory cytokines was measured by quantitative PCR. The key proteins of NF-κB and MAPK signalling pathways were detected by Western blot and immunofluorescence. The result showed that pre-treatment of Na₂SeO₃ (1, 2 and 4 μΜ) decreased the mRNA expression of proinflammatory genes, inhibited the activation of NF-κB and suppressed the phosphorylation of extracellular signal-regulated kinase, P38MAPK and c-Jun N-terminal kinase. This inhibition of inflammation was more apparent in the presence of high-level cortisol (30 ng/mL). These results indicated that selenium has an anti-inflammatory effect, which is mediated via NF-κB and MAPK signalling pathways and is augmented by cortisol in bovine endometrial epithelial cells.     

Cathelicidin LL37 promotes epithelial and smooth-muscle-like differentiation of adipose-derived stem cells through the Wnt/β-catenin and NF-κB pathways

Ureter reconstruction is a difficult procedure in urology. Adipose-derived stem cells (ADSCs), along with multipotency and self-renewal capacity, are a preferred choice for tissue engineering-based ureteral reconstruction. We explored the synergic role of cathelicidin LL37 (LL37) in epithelial and smooth-muscle-like differentiation. ADSCs were separated from adipose tissues of mouse and characterized by flow cytometry. The ADSCs were then stably transfected with pGC-FU-GFP (pGC) or pGC containing full-length LL37 (pGC-LL37), respectively. Cell viability and apoptosis were respectively estimated in the stably transfected cells and non-transfected cells. Then, qRT-PCR and Western blot analysis were used for determinations of epithelial marker expressions after induction by all-trans retinoic acid as well as smooth-muscle-like marker expressions after induction by transforming growth factor-β1. Then, possibly involved signaling pathways and extracellular expression of LL37 were detected. Cell viability and apoptosis were not changed after LL37 overexpression. Expression levels of epithelial and smooth-muscle-like markers were significantly upregulated by LL37 overexpression. Moreover, expressions of key kinases involved in the Wnt/β-catenin pathway as well as epithelial marker were upregulated by the LL37 overexpression, while it was reversed by Wnt/β-catenin inhibitor. Likewise, expressions of key kinases involved in the nuclear factor κB (NF-κB) pathway as well as smooth-muscle-like markers were upregulated by LL37 overexpression, which was reversed by NF-κB inhibitor. LL37 was found in the culture medium. LL37, which could be released into the medium, had no impact on cell proliferation and apoptosis of ADSCs. However, LL37 promoted epithelial and smooth-muscle-like differentiation through activating the Wnt/β-catenin and NF-κB pathways, respectively.     

β-Caryophyllene ameliorates the Mycoplasmal pneumonia through the inhibition of NF-κB signal transduction in mice

BackgroundPneumonia is a frequent infectious disease that mainly affects the children and the global death rate is nearly 19% among children at the below 5 age. β-caryophyllene is an active compound, mainly occurs in the spices and it possesses immense biological activities.ObjectiveThis investigation deliberated to scrutinize the beneficial actions of β-caryophyllene against the M. pneumoniae induced pneumonia.MethodsThe pneumonia was stimulated to the BALB/c mice by infecting them with 100 µl of M. pneumonia for 2 days via nasal drops with the concomitant treatment with 20 mg/kg of β-caryophyllene. The total cells in the BALF of test mice were counted by using the Neuber chamber. The total protein and the pro-inflammatory cytokines status were examined by using the commercial ELISA kits. The PCR technique was used to measure the M. pneumoniae bacterial load. The NF-?B expression was investigated using western blotting. The lung tissues were analyzed microscopically.ResultsThe β-caryophyllene notably diminished the total protein status, total cell count, and bacterial load in the pneumonia provoked mice. The marked reduction in the status of pro-inflammatory regulators was seen in the β-caryophyllene supplemented pneumonia mice. β-caryophyllene also down-regulated the expression of NF-?B thereby reduced the lung inflammation and tissue damages as seen in the result of histological analysis.ConclusionThese findings were confirmed the therapeutic potential of β-caryophyllene against the M. pneumoniae-activated pneumonia in animals.     

LPS-induced NF-κB expression in THP-1Blue cells correlates with neopterin production and activity of indoleamine 2,3-dioxygenase

Neopterin production is induced in human monocyte-derived macrophages and dendritic cells upon stimulation with Th1-type cytokine interferon-γ (IFN-γ). In parallel, IFN-γ induces the tryptophan-(trp)-degrading enzyme indoleamine 2,3-dioxygenase (IDO) and triggers the formation of reactive oxygen species (ROS). Translocation of the signal transduction element nuclear factor-κB (NF-κB) is induced by ROS and accelerates the pro-inflammatory response by activation of other pro-inflammatory pathways. Therefore, a close relationship between NF-κB expression, the production of neopterin and the degradation of trp can be assumed, although this has not been demonstrated so far. In the present in vitro study we compared the influence of lipopolysaccharide (LPS) on NF-κB activation, neopterin formation and the degradation of trp in THP-1Blue cells, which represent the human myelomonocytic cell line THP-1 stably transfected with an NF-κB inducible reporter system.In cells stimulated with LPS, a significant induction of NF-κB was observed, and this was paralleled by an increase of kynureunine (kyn) and neopterin concentrations and a decline of trp. The increase of the kyn to trp quotient indicates accelerated IDO activity. Higher LPS concentrations and longer incubation of cells were associated with higher activities of all three biochemical pathways and significant correlations existed between NF-κB activation, neopterin release and trp degradation (all p < 0.001). We conclude that there is a parallel induction of NF-κB, neopterin formation and trp degradation in monocytic THP-1 cells, which is elicited by pro-inflammatory triggers like LPS during innate immune responses.     

Carabrol suppresses LPS-induced nitric oxide synthase expression by inactivation of p38 and JNK via inhibition of I-κBα degradation in RAW 264.7 cells

Carabrol, isolated from Carpesium macrocephalum, showed anti-inflammatory potential in LPS-induced RAW 264.7 murine macrophages. In present study, carabrol demonstrated the inhibitory activity on pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. In addition, mRNA and protein levels of iNOS and COX-2 were reduced by carabrol. Molecular analysis revealed that these suppressive effects were correlated with the inactivation of p38 and JNK via inhibition of NF-κB activation. Immunoblotting showed that carabrol suppressed LPS-induced degradation of I-κBα and decreased nuclear translocation of p65. Taken together, these results suggest that carabrol can be a modulator of pro-inflammatory signal transduction pathway in RAW 264.7 cells.     

Anti-inflammatory activity of myricetin from Diospyros lotus through suppression of NF-κB and STAT1 activation and Nrf2-mediated HO-1 induction in lipopolysaccharide-stimulated RAW264.7 macrophages

Diospyros lotus is traditionally used for the treatment of diabetes, diarrhea, tumor, and hypertension. The purpose of this study was to investigate the anti-inflammatory effect and underlying molecular mechanisms of myricetin in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Myricetin dose-dependently suppressed the production of pro-inflammatory mediators (NO, iNOS, PGE₂, and COX-2) in LPS-stimulated RAW264.7 macrophages. Myricetin administration decreased the production of NO, iNOS, TNF-α, IL-6, and IL-12 in mice. Myricetin decreased NF-κB activation by suppressing the degradation of IκBα, nuclear translocation of p65 subunit of NF-κB, and NF-κB DNA binding activity in LPS-stimulated RAW264.7 macrophages. Moreover, myricetin attenuated the phosphorylation of STAT1 and the production of IFN-β in LPS-stimulated RAW264.7 macrophages. Furthermore, myricetin induced the expression of HO-1 through Nrf2 translocation. In conclusion, these results suggest that myricetin inhibits the production of pro-inflammatory mediators through the suppression of NF-κB and STAT1 activation and induction of Nrf2-mediated HO-1 expression in LPS-stimulated RAW264.7 macrophages.     

Degraded λ-carrageenan activates NF-κB and AP-1 pathways in macrophages and enhances LPS-induced TNF-α secretion through AP-1

Background

Carrageenan (CGN), a high molecular weight sulfated polysaccharide, is a traditional ingredient used in food industry. Its degraded forms have been identified as potential carcinogens, although the mechanism remains unclear.

Methods

The effects of degraded λ-carrageenan (λ-dCGN) on murine RAW264.7 cells and human THP-1-derived macrophage cells were investigated by studying its actions on tumor necrosis factor alpha (TNF-α) secretion, Toll-like receptor 4 (TLR4) expression, and activation of nuclear factor-κb (NF-κB) and activation protein-1 (AP-1) pathways.

Results

We found that λ-dCGN was much stronger than native λ-CGN in the activation of macrophages to secrete TNF-α. Treatment of RAW264.7 cells with λ-dCGN resulted in the upregulation of TLR4, CD14 and MD-2 expressions, but it did not increase the binding of lipopolysacchride (LPS) with macrophages. Meanwhile, λ-dCGN treatment activated NF-κB via B-cell lymphoma/leukemia 10 (Bcl10) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) phosphorylation. In addition, λ-dCGN induced extracellular signal-regulated kinases/1/2/mitogen-activated protein kinases (ERK1/2/MAPK) and AP-1 activation. Interestingly, pretreatment of RAW264.7 cells with λ-dCGN markedly enhanced LPS-stimulated TNF-α secretion. This pretreatment resulted in the enhanced phosphorylation of ERK1/2 and c-Jun N-terminal kinase (JNK) and intensified activation of AP-1.

Conclusions

λ-dCGN induced an inflammatory reaction via both NF-κB and AP-1, and enhanced the inflammatory effect of LPS through AP-1 activation.

General significance

The study demonstrated the role of λ-dCGN to induce the inflammatory reaction and to aggravate the effect of LPS on macrophages, suggesting that λ-dCGN produced during food processing and gastric digestion may be a safety concern.     

Scaffold compound L971 exhibits anti-inflammatory activities through inhibition of JAK/STAT and NFκB signalling pathways

JAK/STAT and NFκB signalling pathways play essential roles in regulating inflammatory responses, which are important pathogenic factors of various serious immune-related diseases, and function individually or synergistically. To find prodrugs that can treat inflammation, we performed a preliminary high-throughput screening of 18 840 small molecular compounds and identified scaffold compound L971 which significantly inhibited JAK/STAT and NFκB driven luciferase activities. L971 could inhibit the constitutive and stimuli-dependent activation of STAT1, STAT3 and IκBα and could significantly down-regulate the proinflammatory gene expression in mouse peritoneal macrophages stimulated by LPS. Gene expression profiles upon L971 treatment were determined using high-throughput RNA sequencing, and significant differentially up-regulated and down-regulated genes were identified by DESeq analysis. The bioinformatic studies confirmed the anti-inflammatory effects of L971. Finally, L971 anti-inflammatory character was further verified in LPS-induced sepsis shock mouse model in vivo. Taken together, these data indicated that L971 could down-regulate both JAK/STAT and NFκB signalling activities and has the potential to treat inflammatory diseases such as sepsis shock.     

Tetracyclines downregulate the production of LPS-induced cytokines and chemokines in THP-1 cells via ERK,p38, and nuclear factor-κB signaling pathways

Recent reports have shown that antibiotics such as macrolide, aminoglycoside, and tetracyclines have immunomodulatory effects in addition to essential antibiotic effects. These agents may have important effects on the regulation of cytokine and chemokine production. However, the precise mechanism is unknown. This time, we used Multi Plex to measure the production of cytokines and chemokines following tetracycline treatment of lipopolysaccharide (LPS)-induced THP-1 cells. The signaling pathways were investigated with Western blotting analysis. Three tetracyclines significantly suppressed the expression of cytokines and chemokines induced by LPS. Minocycline (50 μg/ml), tigecycline (50 μg/ml), or doxycycline (50 μg/ml) were added after treatment with LPS (10 μg/ml). Tumor necrosis factor-α was downregulated to 16%, 14%, and 8%, respectively, after 60 min compared to treatment with LPS without agents. Interleukin-8 was downregulated to 43%, 32%, and 26% at 60 min. Macrophage inflammatory protein (MIP)-1α was downregulated to 23%, 33%, and 16% at 120 min. MIP-1β was downregulated to 21%, 11%, and 2% at 120 min. Concerning about signaling pathways, the mechanisms of the three tetracyclines might not be the same. Although the three tetracyclines showed some differences in the time course, tetracyclines modulated phosphorylation of the NF-κB pathway, p38 and ERK1/2/MAPK pathways, resulting in inhibition of cytokine and chemokine production. In addition, SB203580 (p38 inhibitor) and U0126 (ERK1/2 inhibitor) significantly suppressed the expression of TNF-α and IL-8 in LPS-stimulated THP-1 cells. And further, the NF-κB inhibitor, BAY11-7082, almost completely suppressed LPS-induced these two cytokines production. Thus, more than one signaling pathway may be involved in tetracyclines downregulation of the expression of LPS-induced cytokines and chemokines in THP-1 cells. And among the three signaling pathways, NF-κB pathway might be the dominant pathway on tetracyclines modification the LPS-induced cytokines production in THP-1 cells. In general, minocycline and doxycycline suppressed the production of cytokines and chemokines in LPS-stimulated THP-1 cell lines via mainly the inhibition of phosphorylation of NF-κB pathways. Tigecycline has the same structure as the other tetracyclines, however, it showed the different properties of cytokine modulation in the experimental time course.     

Anti-inflammatory effect of soyasaponins through suppressing nitric oxide production in LPS-stimulated RAW 264.7 cells by attenuation of NF-κB-mediated nitric oxide synthase expression

The anti-inflammatory properties of soyasaponins (especially soyasaponins with different chemical structures) have scarcely been investigated. We investigated the inhibitory effects of five structural types of soyasaponins (soyasaponin A¹, A², I and soyasapogenol A, B) on the induction of nitric oxide (NO) and inducible NO synthase (iNOS) in murine RAW 264.7 cells activated with lipopolysaccharide (LPS). Soyasaponin A¹, A² and I (25-200 μg/mL) dose-dependently inhibited the production of NO and tumor necrosis factor α (TNF-α) in LPS-activated macrophages, whereas soyasapogenol A and B did not. Furthermore, soyasaponin A¹, A² and I suppressed the iNOS enzyme activity and down-regulated the iNOS mRNA expression both in a dose-dependent manner. The reporter gene assay revealed that soyasaponin A¹, A² and I decreased LPS-induced nuclear factor kappa B (NF-κB) activity. Soyasaponin A¹, A² and I exhibit anti-inflammatory properties by suppressing NO production in LPS-stimulated RAW 264.7 cells through attenuation of NF-κB-mediated iNOS expression. It is proposed that the sugar chains present in the structures of soyasaponins are important for their anti-inflammatory activities. These results have important implication for using selected soyasaponins towards the development of effective chemopreventive and anti-inflammatory agents.