Inhibition of TNF‐α‐mediated endothelial cell–monocyte cell adhesion and adhesion molecules expression by the resveratrol derivative,trans‐3,5,4′‐trimethoxystilbene

Resveratrol (RSV) has been shown to have anti‐inflammatory activity and to have a protective role against atherosclerosis. Here it is shown, for the first time, that its derivative trans‐3,5,4′‐trimethoxystilbene (TMS) may be a more potent anti‐inflammatory agent than resveratrol. A comparative analysis of the inhibitory activities of related stilbenes, resveratrol, TMS and polydatin (PD), on monocyte adhesion to TNF‐α‐activated endothelial cells showed TMS to be the most effective, with PD being the least effective. RSV and its analogues inhibited, albeit differentially, the protein and mRNA expression levels of inducible cell adhesion molecules, ICAM‐1 and VCAM‐1, in cultured endothelial cells. The mechanism of the inhibitory effects of these stilbenes on endothelial cell–monocyte cell adhesion can be attributed mainly to inhibition of NF‐κB pathway activation. The results demonstrate that all three investigated stilbene compounds, especially TMS, exhibit a potent inhibitory effect on inflammation‐induced cell–cell adhesion, expression of adhesion molecules and activation of the NF‐κB pathway. Copyright © 2010 John Wiley & Sons, Ltd.     

Inhibitory effect of Thuja orientalis on TNF-α-induced vascular inflammation

Vascular inflammation is involved in the initiation and progression of vascular diseases including atherosclerosis. While conducting in vitro screening of 600 medicinal plant extracts, an aqueous extract of Thuja orientalis (ATO) was found to exhibit antiinflammatory activity in human umbilical vein endothelial cells (HUVEC). In the current study, the antiinflammatory activity of ATO and possible mechanisms for this were investigated in HUVEC. Preincubation with ATO (20 μg/mL) suppressed tumor necrosis factor‐α (TNF‐α)‐induced expression of adhesion molecules including intercellular adhesion molecule‐1 (ICAM‐1), vascular cell adhesion molecule‐1 (VCAM‐1) and E‐selectin at both the protein and mRNA levels. ATO also inhibited U937 monocyte adhesion to HUVEC stimulated by TNF‐α. In addition, ATO attenuated TNF‐α‐induced p65 NF‐κB translocation into the nucleus and phosphorylation of IκB‐α. Furthermore, ATO significantly inhibited TNF‐α‐induced intracellular reactive oxygen species (ROS) production. Overall, the present data suggest that ATO can suppress TNF‐α‐induced vascular inflammatory processes, possibly via inhibition of ROS and NF‐κB activation, in HUVEC. Copyright © 2010 John Wiley & Sons, Ltd.     

Hydroxy‐Safflower Yellow A inhibits the TNFR1‐Mediated Classical NF‐κB Pathway by Inducing Shedding of TNFR1

Hydroxy‐safflower yellow A (HSYA) is the major active component of safflower, a traditional Asia herbal medicine well known for its cardiovascular protective activities. The purpose of this study was to investigate the effect of HSYA on TNF‐α‐induced inflammatory responses in arterial endothelial cells (AECs) and to explore the mechanisms involved. The results showed that HSYA suppressed the up‐regulation of ICAM‐1 expression in TNF‐α‐stimulated AECs in a dose‐dependent manner. High concentration (120 μM) HSYA significantly inhibited the TNF‐α‐induced adhesion of RAW264.7 cells to AECs. HSYA blocked the TNFR1‐mediated phosphorylation and degradation of IκBα and also prevented the nuclear translocation of NF‐κB p65. Moreover, HSYA reduced the cell surface level of TNFR1 and increased the content of sTNFR1 in the culture media. TNF‐α processing inhibitor‐0 (TAPI‐0) prevented the HSYA inhibition of TNFR1‐induced IκBα degradation, implying the occurrence of TNFR1 shedding. Furthermore, HSYA induced phosphorylation of TNF‐α converting enzyme (TACE) at threonine 735, which is thought to be required for its activation. Conclusively, HSYA suppressed TNF‐α‐induced inflammatory responses in AECs, at least in part by inhibiting the TNFR1‐mediated classical NF‐κB pathway. TACE‐mediated TNFR1 shedding can be involved in this effect. Our study provides new evidence for the antiinflammatory and anti‐atherosclerotic effects of HSYA. Copyright © 2016 John Wiley & Sons, Ltd.     

Diosmetin exhibits anti‐proliferative and anti‐inflammatory effects on TNF‐α‐stimulated human rheumatoid arthritis fibroblast‐like synoviocytes through regulating the Akt and NF‐κB signaling pathways

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by inflammation and proliferation of synovial tissues. Diosmetin is a bioflavonoid possessing an anti‐inflammatory property. Herein, we aimed to study the effects of diosmetin on the inflammation and proliferation of RA fibroblast‐like synoviocytes MH7A cells. MH7A cell proliferation was measured using cell counting kit‐8 assay. Cell apoptosis was examined using flow cytometry. The production of inflammatory cytokines including interleukin (IL)‐1β, IL‐6, IL‐8, and matrix metalloproteinase‐1 (MMP‐1) was measured using enzyme‐linked immunosorbent assay (ELISA). Results showed that diosmetin inhibited tumor necrosis factor‐α (TNF‐α)‐induced proliferation increase in MH7A cells in a dose‐dependent manner. Diosmetin treatment resulted in an increase in apoptotic rates and a reduction in TNF‐α‐induced production of IL‐1β, IL‐6, IL‐8, and MMP‐1 in MH7A cells. Furthermore, diosmetin inhibited TNF‐α‐induced activation of protein kinase B (Akt) and nuclear factor‐κB (NF‐κB) pathways in MH7A cells. Suppression of Akt or NF‐κB promoted apoptosis and inhibited TNF‐α‐induced proliferation increase and production of IL‐1β, IL‐6, IL‐8, and MMP‐1 in MH7A cells, and diosmetin treatment enhanced these effects. Taken together, these findings suggested that diosmetin exhibited anti‐proliferative and anti‐inflammatory effects via inhibiting the Akt and NF‐κB pathways in MH7A cells.     

Inhibition of TNF‐α‐Induced MUC5AC Mucin Gene Expression and Production by Wogonin Through the Inactivation of NF‐κB Signaling in Airway Epithelial Cells

In this study, we investigated whether wogonin significantly affects MUC5AC mucin gene expression and production in human airway epithelial cells. Confluent NCI‐H292 cells were pretreated with wogonin for 30 min and then stimulated with tumor necrosis factor‐α (TNF‐α) for 24 h or the indicated periods. The MUC5AC mucin gene expression and mucin protein production were measured by RT‐PCR and ELISA, respectively. We found that incubation of NCI‐H292 cells with wogonin significantly inhibited mucin production and down‐regulated MUC5AC gene expression induced by TNF‐α in a dose‐dependent fashion. To elucidate the action mechanism of wogonin, effect of wogonin on TNF‐α‐induced NF‐κB signaling pathway was investigated by western blot analysis. Wogonin inhibited NF‐κB activation induced by TNF‐α. Inhibition of IKK by wogonin led to the suppression of IκB phosphorylation and degradation, p65 nuclear translocation and NF‐κB‐regulated gene expression. This, in turn, led to the down‐regulation of MUC5AC protein production in NCI‐H292 cells. Wogonin also inhibited the gene products involved in cell survival (Bcl‐2) and proliferation (cyclooxygenase‐2). These results suggest that wogonin inhibits the NF‐κB signaling pathway, which may explain its role in the inhibition of MUC5AC mucin gene expression and production. Copyright © 2013 John Wiley & Sons, Ltd.     

Nerolidol Protects Against LPS‐induced Acute Kidney Injury via Inhibiting TLR4/NF‐κB Signaling

Acute kidney injury (AKI) is a critical care syndrome, resulting in acute reduction of renal function and up to 22% mortality of hospitalized patients. Nerolidol is a major component in several essential oils that possesses various pharmacological properties. The present study aimed to investigate the potential effect of nerolidol on lipopolysaccharide (LPS)‐induced AKI. Nerolidol dose‐dependently reduced the pathological injuries of kidney induced by LPS in rats. Nerolidol significantly decreased the levels of blood urea nitrogen and creatinine in LPS‐treated rats in a dose‐dependent manner. In addition, nerolidol inhibited LPS‐induced decrease of cell viability in NRK‐52E rat proximal tubular cells, which effect was concentration dependent. Nerolidol notably inhibited the increase of TNFα and IL‐1β in LPS‐treated rats and the mRNA expression of TNFα and IL‐1β in LPS‐treated NRK‐52E cells. Nerolidol suppressed the increase of toll‐like receptor 4 (TLR4) expression, phosphorylation and nuclear translocation of p65 NF‐κB in kidneys of LPS‐treated rats and LPS‐treated NRK‐52E cells. Overexpression of TLR4 and p65 NF‐κB significantly suppressed nerolidol‐induced inhibition of TNFα and IL‐1β expression and increase of cell viability in LPS‐treated cells. In summary, we found that nerolidol played a critical anti‐inflammatory effects through inhibition of TLR4/NF‐κB signaling and protected against LPS‐induced AKI. Copyright © 2017 John Wiley & Sons, Ltd.     

Chelidonine inhibits TNF‐α‐induced inflammation by suppressing the NF‐κB pathways in HCT116 cells

Nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) is a complex that regulates several hundreds of genes, including those involved in immunity and inflammation, survival, proliferation, and the negative feedback of NF‐κB signaling. Chelidonine, a major bioactive, isoquinoline alkaloid ingredient in Chelidonium majus, exhibits antiinflammatory pharmacological properties. However, its antiinflammatory molecular mechanisms remain unclear. In this work, we explored the effect of chelidonine on TNF‐induced NF‐κB activation in HCT116 cells. We found chelidonine inhibited the phosphorylation and degradation of the inhibitor of NF‐κB alpha and nuclear translocation of RELA. Furthermore, by inhibiting the activation of NF‐κB, chelidonine downregulated target genes involved in inflammation, proliferation, and apoptosis. Chelidonine also inhibited mitogen‐activated protein kinase pathway activation by blocking c‐Jun N‐terminal kinase and p38 phosphorylation. These results suggest that chelidonine may be a potential therapeutic agent against inflammatory diseases in which inhibition of NF‐κB activity plays an important role.     

A Polyphenol‐rich Pomegranate Fruit Extract Suppresses NF‐κB and IL‐6 Expression by Blocking the Activation of IKKβ and NIK in Primary Human Chondrocytes

Pomegranate fruit extract (PE) rich in polyphenols has been shown to exert chondroprotective effects, but the mechanism is not established. Here, we used an in vitro model of inflammation in osteoarthritis (OA) to investigate the potential of PE to suppress interleukin 1 beta (IL‐1β)‐stimulated expression of inflammatory cytokine IL‐6, generation of reactive oxygen species (ROS) levels, and investigated the mechanism of NF‐κB inhibition by analyzing the activation of the kinases upstream of IκBα in primary human chondrocytes. Total and phosphorylated forms of kinases and expression of IL‐6 were determined at protein and mRNA levels by western immunoblotting and Taqman assay, respectively. Dihydrorhodamine 123 staining estimated ROS generation. Pomegranate fruit extract inhibited the mRNA and protein expression of IL‐6, generation of ROS, and inhibited the IL‐1β‐mediated phosphorylation of inhibitor of nuclear factor kappa‐B kinase subunit beta (IKKβ), expression of IKKβ mRNA, degradation of IκBα, and activation and nuclear translocation of NF‐κB/p65 in human chondrocytes. Importantly, phosphorylation of NF‐κB‐inducing kinase was blocked by PE in IL‐1β‐treated human OA chondrocytes. Taken together, these data suggest that PE exerts the chondroprotective effect(s) by suppressing the production of IL‐6 and ROS levels. Inhibition of NF‐κB activation by PE was blocked via modulation of activation of upstream kinases in human OA chondrocytes. Copyright © 2017 John Wiley & Sons, Ltd.     

Anti‐inflammatory Effects of Ginsenosides Rg5, Rz1, and Rk1: Inhibition of TNF‐α‐induced NF‐κB,COX‐2, and iNOS transcriptional expression

In the course of this experiment on the anti‐inflammatory effect of ginsenosides, protopanaxdiol ginsenosides have shown inhibition activities in inflammatory responses: NF‐κB, COX‐2, and iNOS were induced by TNF‐α. The responses of this experiment were evaluated by NF‐κB‐luciferase assay and RT‐PCR experiment of COX‐2 and iNOS genes. The NF‐κB expressions were inhibited by ginsenosides Rd, Rg₅, Rz₁, and Rk₁ in a dose‐dependent manner. The IC₅₀ values were 3.47, 0.61, 0.63, and 0.75 μM, respectively. Particularly, ginsenosides Rg₅, Rz₁, and Rk₁ as converted ginsenosides from primary protopanaxdiol ginsenosidess significantly inhibited COX‐2 and iNOS gene expression. These inhibition levels were similar to sulfasalazine as reference material. Copyright © 2014 John Wiley & Sons, Ltd.     

Isoforskolin and forskolin attenuate lipopolysaccharide‐induced inflammation through TLR4/MyD88/NF‐κB cascades in human mononuclear leukocytes

The principal active component of isoforskolin (ISOF) is from the plant Coleus forskohlii, native to China, which has attracted much attention for its biological effects. We hypothesize that ISOF and forskolin (FSK) pretreatment attenuates inflammation induced by lipopolysaccharide (LPS) related to toll‐like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor kappa B (NF‐κB) signaling. Mononuclear leukocytes (MLs) from healthy donors' blood samples were separated by using density gradient centrifugation. Protein levels of TLR4, MyD88, and NF‐κB were detected using western blot and inflammatory cytokines interleukin (IL) 1β, IL‐2, IL‐6, IL‐21, IL‐23, tumor necrosis factor (TNF) α, and TNF‐β were tested by enzyme‐linked immunosorbent assay and Quantibody array in MLs. Our results showed that LPS augmented the protein levels of TLR4, MyD88, and NF‐κB in MLs and the production of IL‐1β, IL‐2, IL‐6, IL‐21, IL‐23, TNF‐α, and TNF‐β in supernatants of MLs. Despite treatment with ISOF and FSK prior to LPS, the protein levels of TLR4, MyD88, NF‐κB, IL‐1β, IL‐2, IL‐6, IL‐21, IL‐23, TNF‐α, and TNF‐β in MLs were apparently decreased. roflumilast (RF) and dexamethasone (DM) had a similar effect on MLs with ISOF and FSK. Our results, for the first time, have shown that ISOF and FSK attenuate inflammation in MLs induced by LPS through down‐regulating protein levels of IL‐1β and TNF‐α, in which TLR4/MyD88/NF‐κB signal pathway could be involved.     

Astragaloside IV inhibits TGF‐β1‐induced epithelial‐mesenchymal transition through inhibition of the PI3K/Akt/NF‐κB pathway in gastric cancer cells

Astragaloside IV (AS‐IV) has been reported to possess anti‐metastasis activity in cancer cells. However, it is unknown whether AS‐IV could inhibit epithelial‐mesenchymal transition (EMT), a cellular de‐differentiation program that promotes metastasis, in cancer cells. The aim of this study was to study the effect and mechanism of AS‐IV on EMT in gastric cancer (GC) cells. The results showed that AS‐IV significantly inhibited cell viability, invasion, and migration of GC cells. The E‐cadherin to N‐cadherin switch and expression of Vimentin and metastasis‐related genes were induced by transforming growth factor β1 (TGF‐β1), whereas AS‐IV reversed the induction. In addition, AS‐IV inhibited TGF‐β1‐induced activation of PI3K/Akt/NF‐κB. Inhibition of the PI3K/Akt/NF‐κB pathway reversed TGF‐β1‐induced EMT. In conclusion, AS‐IV inhibited TGF‐β1‐induced EMT through inhibition of the PI3K/Akt/NF‐κB pathway in GC cells. AS‐IV might be an effective candidate for the treatment for GC.     

Panax notoginseng saponins suppress lipopolysaccharide‐induced barrier disruption and monocyte adhesion on bEnd.3 cells via the opposite modulation of Nrf2 antioxidant and NF‐κB inflammatory pathways

Dysfunction of the blood‐brain barrier (BBB) is a prerequisite for the pathogenesis of many cerebral diseases. Oxidative stress and inflammation are well‐known factors accounting for BBB injury. Panax notoginseng saponins (PNS), a clinical commonly used drug against cerebrovascular disease, possess efficient antioxidant and anti‐inflammatory activity. In the present study, the protective effects of PNS on lipopolysaccharide (LPS)‐insulted cerebral microvascular endothelial cells (bEnd.3) were assessed and the underlying mechanisms were investigated. The results showed that PNS mitigated the decrease of Trans‐Endothelial Electrical Resistance, increase of paracellular permeability, and loss of tight junction proteins in bEnd.3 BBB model. Meanwhile, PNS suppressed the THP‐1 monocytes adhesion on bEnd.3 monolayer. Moreover, PNS prevented the pro‐inflammatory cytokines secretion and reactive oxygen species generation in bEnd.3 cells stimulated with LPS. Mechanism investigations suggested that PNS promoted the Akt phosphorylation, activated Nrf2 antioxidant signaling, and inhibited the NF‐κB activation. All the effects of PNS could be abolished by PI3K inhibition at different levels. Taken together, these observations suggest that PNS may act as an extrinsic regulator that activates Nrf2 antioxidant defense system depending on PI3K/Akt and inhibits NF‐κB inflammatory signaling to attenuate LPS‐induced BBB disruption and monocytes adhesion on cerebral endothelial cells in vitro.     

1,2,3,6‐tetra‐O‐galloyl‐β‐D‐allopyranose gallotannin isolated,from Euphorbia jolkini,attenuates LPS‐induced nitric oxide production in macrophages

Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including vasodilatation and macrophage‐mediated immunity. Macrophages express inducible NO synthase (iNOS) and produce NO after lipopolysaccharide (LPS) stimulation. Gallotannins are water‐soluble polyphenols with wide‐ranging biological activities. Various chemical structures of gallotannins occurring in medicinal and food plants that are used worldwide showed several remarkable biological and pharmacological activities. In the present study, we examined the inhibitory effects of gallotannin 1,2,3,6‐tetra‐O‐galloyl‐β‐D‐allopyranose (GT24) isolated from Euphorbia jolkini on the LPS‐induced NO production and underlying mechanisms of action. GT24 dose‐dependently decreased LPS‐induced NO production and iNOS expression in J774A.1 macrophages. In addition, GT24 inhibited LPS‐induced activation of nuclear factor (NF)‐κB as indicated by inhibition of degradation of I‐κBα, nuclear translocation of NF‐κB, and NF‐κB dependent gene reporter assay. Our results suggest that GT24 possesses an inhibitory effect on the LPS‐induced inflammatory reaction. Copyright © 2010 John Wiley & Sons, Ltd.     

Quercetin protects against cisplatin‐induced acute kidney injury by inhibiting Mincle/Syk/NF‐κB signaling maintained macrophage inflammation

Acute kidney injury (AKI) with high incidence and mortality is the main cause of chronic kidney disease. Previous studies have indicated that quercetin, an abundant flavonoid in plants, exhibited renoprotective role in AKI. However, the underlying mechanism is largely unknown. In this study, we try to explore whether quercetin protects against AKI by inhibiting macrophage inflammation via regulation of Mincle/Syk/NF‐κB signaling. The results demonstrated that quercetin can significantly inhibit expression and secretion of IL‐1β, IL‐6, and TNF‐α in LPS‐induced bone marrow‐derived macrophages (BMDMs) and reduce activity of Mincle/Syk/NF‐κB signaling in vitro. We also found that quercetin can strongly reduce the concentration of serum creatinine, BUN, IL‐1β, IL‐6, and TNF‐α in cisplatin‐induced AKI model. Furthermore, quercetin down‐regulated protein levels of Mincle, phosphorylated Syk and NF‐κB in kidney macrophages of AKI, as well as inhibited M1, up‐regulated M2 macrophage activity. Notably, the down‐regulation of LPS‐induced inflammation by quercetin was reversed after adding TDB (an agonist of Mincle) in BMDMs, suggesting that quercetin suppresses macrophage inflammation may mainly through inhibiting Mincle and its downstream signaling. In summary, these findings clarified a new mechanism of quercetin improving AKI‐induced kidney inflammation and injury, which provides a new drug option for the clinical treatment of AKI.     

Paeonol ameliorates monosodium urate‐induced arthritis in rats through inhibiting nuclear factor‐κB‐mediated proinflammatory cytokine production

Moutan Cortex has been widely used to treat various types of arthritis in traditional Chinese medicine. Paeonol is isolated as an active ingredient from Moutan Cortex. However, the effect and potential mechanism of paeonol on gouty arthritis have not been evaluated. In this study, rats were treated intragastrically with paeonol for consecutive 7 days. On Day 5, rats were intra‐articularly injected with monosodium urate (MSU) crystals in the ankle joints to induce MSU‐induced arthritis (MIA). Paw volume was detected at various time points. Gait score was measured at 24 hr after MSU crystal injection. Ankle joints were collected for evaluation of histological score and expression of proinflammatory cytokines using hematoxylin and eosin staining and immunohistochemistry staining, respectively. Nuclear level of nuclear factor (NF)‐κBp65 in synovial tissues was analyzed by western blot assay. NF‐κB DNA‐binding activity was measured by enzyme linked immunosorbent assay. Paeonol markedly lowered the paw volume, gait score, and histological score in MIA rats. Mechanistically, paeonol markedly reduced the expression of TNF‐α, IL‐1β, and IL‐6 in synovial tissues of MIA rats. In addition, the elevated level of p65 in nucleus and NF‐κB DNA‐binding activity in synovial tissues of MIA rats were reduced significantly by paeonol treatment. These findings suggest that paeonol exerts anti‐inflammatory effect in MIA rats through inhibiting expression of proinflammatory cytokines and NF‐κB activation.