Tectorigenin protects against experimental fulminant hepatic failure by regulating the TLR4/mitogen‐activated protein kinase and TLR4/nuclear factor‐κB pathways and autophagy

Tectorigenin has received attention due to its antiproliferation, anti‐inflammatory, and antioxidant activities. In this study, we investigated the effects of tectorigenin on lipopolysaccharide (LPS)/D‐galactosamine(D‐GalN)‐induced fulminant hepatic failure (FHF) in mice and LPS‐stimulated macrophages (RAW 264.7 cells). Pretreatment with tectorigenin significantly reduced the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), histological injury, apoptosis, and the mortality of FHF mice, by suppressing the production of inflammatory cytokines such as TNF‐α and IL‐6. Tectorigenin also suppressed the activation of the inflammatory response in LPS‐stimulated RAW 264.7 cells. Tectorigenin‐induced protection is mediated through its mitigation of TLR4 expression, inhibition of mitogen‐activated protein kinase (MAPK) and nuclear factor‐κB (NF‐κB) pathway activation, and promotion of autophagy in FHF mice and LPS‐stimulated RAW 264.7 cells. Therefore, tectorigenin has therapeutic potential for FHF in mice via the regulation of TLR4/MAPK and TLR4/NF‐κB pathways and autophagy.     

Methylalpinumisoflavone Inhibits Lipopolysaccharide‐Induced Inflammation in Microglial Cells by the NF‐kappaB and MAPK Signaling Pathway

Neuroinflammation is chronic inflammation within the brain that is attributed to prolonged activation of microglial cells and results in neurodegenerative events, such as neuronal dysfunction and neuronal loss. Therefore, suppression of neuroinflammation would theoretically slow progression of neurodegenerative disease. In this study, we investigated the anti‐inflammatory effects of 4′‐O‐methylalpinumisoflavone (methylalpinumisoflavone), isolated from Cudrania tricuspidata, against LPS‐induced microglial activation in BV2 cells. Exposure of BV2 cells to LPS (0.5 µg/mL) significantly increased production of pro‐inflammatory mediators, including NO, PGE₂, and pro‐inflammatory cytokines. Conversely, pre‐treatment with methylalpinumisoflavone (10 and 20 µg/mL) prior to treatment with LPS resulted in a significant decrease of LPS‐induced production of pro‐inflammatory mediators in a dose‐dependent manner. In addition, reduction of pro‐inflammatory mediators by treatment with methylalpinumisoflavone prior to treatment with LPS was accompanied by a decrease in translocation of NF‐κB p50 and p65 from the cytoplasm to the nucleus and by a decrease in activation of mitogen‐activated protein kinases (MAPKs), such as ERK1/2 and JNK. Taken together, these results suggest that methylalpinumisoflavone suppressed LPS‐induced microglial activation and production of pro‐inflammatory mediators by decreasing NF‐κB signaling and by phosphorylation of MAPKs. These results suggest the potential of methylalpinumisoflavone as an anti‐inflammatory drug candidate. Copyright © 2012 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.     

Retracted: Baicalin relieves lipopolysaccharide‐evoked inflammatory injury through regulation of miR‐21 in H9c2 cells

Myocarditis is a common heart disease which lacks effective treatment till now. Baicalin possesses plenty of activities, including anti‐inflammation. In this investigation, we attempted to investigate the influences of Baicalin on Lipopolysaccharide (LPS)‐evoked H9c2 cells.Cells viability, apoptosis, and expressions of apoptosis‐associated proteins were, respectively, measured utilizing CCK‐8 assay, flow cytometry and western blot. The levels of IL‐6 and TNF‐α were detected through enzyme‐linked immunosorbent assay, western blot and qRT‐PCR. miR‐21 expression was detected through qRT‐PCR and was silenced using cell transfection. The expressions of NF‐κB and PDCD4/JNK pathways related proteins were measured through western blot. We found that LPS stimulation induced cell apoptosis and upregulation of IL‐6 and TNF‐α. Baicalin treatment effectively suppressed LPS‐induced inflammation and apoptosis. The NF‐κB and PDCD4/JNK pathways were blocked by Baicalin. Additionally, the enhanced expression of miR‐21 triggered by LPS was further elevated by Baicalin. Further study revealed that the inhibiting effects of Baicalin on LPS‐evoked injury were largely attenuated by knockdown of miR‐21. Moreover, the associated NF‐κB and JNK pathways, which were suppressed by Baicalin treatment, were then activated by knockdown of miR‐21. Our present study revealed that Baicalin alleviated LPS‐evoked inflammatory injury via suppressing the NF‐κB and PDCD4/JNK pathways through regulating miR‐21 expression.     

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.     

Kaempferitrin inhibits proliferation,induces apoptosis,and ameliorates inflammation in human rheumatoid arthritis fibroblast‐like synoviocytes

Rheumatoid arthritis (RA) is a complex chronic inflammatory disease that is associated with the aberrant activation of fibroblast‐like synoviocytes (FLS). Kaempferitrin is a natural flavonoid glycoside that possesses anti‐inflammatory bioactivity. However, the effect of kaempferitrin on RA has not yet been revealed. The aim of the present study was to investigate the effect of kaempferitrin on human RA‐FLS MH7A cell line. We found that kaempferitrin inhibited proliferation and induced apoptosis of MH7A cells. Kaempferitrin decreased the levels of interleukin (IL)‐1β, IL‐6, tumor necrosis factor (TNF)‐α, matrix metalloproteinase (MMP)‐1, and MMP‐3 in MH7A cells. Moreover, kaempferitrin blocked the activation of nuclear factor‐κB (NF‐κB) and protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathways. Furthermore, treatment with kaempferitrin decreased paw thickness and arthritis scores, and reduced the serum levels of IL‐1β, IL‐6, and TNF‐α in a collagen‐induced arthritis mouse model. In conclusion, kaempferitrin inhibited cell proliferation, induced cell apoptosis, and ameliorated inflammation of RA‐FLS by suppressing the NF‐κB and Akt/mTOR pathways.     

Suppressive Effect of Flavonoids from Korean Citrus aurantium L. on the Expression of Inflammatory Mediators in L6 Skeletal Muscle Cells

Citrus fruits (Citrus aurantium L.) have long been used as a traditional herbal medicine. The benefits of the flavonoids found in Citrus aurantium L. include anti‐inflammation, anti‐cancer, anti‐viral and anti‐bacterial activities, and enhancement of the immune response. The study investigated the effect of the flavonoids isolated from Citrus aurantium L. native to Korea on the production of pro‐inflammatory mediators by blocking signal transduction mediated by nuclear factor‐kappa B (NF‐κB) and mitogen‐activated protein kinases (MAPKs) in lipopolysaccharide (LPS)‐induced L6 skeletal muscle cells. The flavonoids decreased the production of inducible nitric oxide synthase, cyclooxygenase‐2, interleukin‐6 and tumor necrosis factor‐alpha by suppressing NF‐κB and MAPKs signal pathways in LPS‐induced L6 skeletal muscle cells. These findings suggest that the flavonoids isolated from Korea Citrus aurantium L. might have anti‐inflammatory effects that regulate the expression of inflammatory mediators in L6 skeletal muscle cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Withanolides against TLR4‐Activated Innate Inflammatory Signalling Pathways: A Comparative Computational and Experimental Study

Innate inflammations are dominant causes of poor health and high mortality. The pathogen‐associated molecular pattern and lipopolysaccharide (LPS) are sensed by immune cells through activation of toll‐like receptor 4 leading to mitogen‐activated protein kinases (MAPKs) and NF‐κB activations. Controlled MAPK and Nf‐κB inhibitors have been proposed as potential antiinflammatory drugs. Withania somnifera is an important medicinal herb with known antiinflammatory activity. In this study, the selected Withania somnifera extracts and withanolides were analysed on LPS‐induced macrophages comparatively. Molecular docking analysis revealed withaferin A, withanone and withanolide A as effective withanolides against inflammatory target molecules. In experiments, withaferin A and withanone treatment had prominent suppressions on LPS‐induced expression of pro‐inflammatory cytokines in bone marrow‐derived macrophages. Withaferin A regulated all the major four pathways (MAPKs and NF‐κB) involved in innate inflammations. Similarly among the Withania extracts analysed, the in vitro propagated leaf and field grown root extracts containing high withaferin A content suppressed the inflammatory molecules through NF‐κB and MAPK pathways. Withaferin A was found to be best in suppressing the activated inflammatory pathways among all the analysed withanolides. Therefore, withaferin A and extracts with high withaferin A content can be used as promising drug candidates against innate inflammations. 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.     

Mogroside IIIE Attenuates LPS‐Induced Acute Lung Injury in Mice Partly Through Regulation of the TLR4/MAPK/NF‐κB Axis via AMPK Activation

Acute lung injury (ALI) often leads to high mortality, and there is as yet no effective drug treatment. The present study aimed to investigate protective effects of mogroside IIIE (MGIIIE, a cucurbitane‐type triterpenoid from Siraitia grosvenorii Fruits) in experimental ALI and its underlying mechanism. MGIIIE (1, 10 0r 20 mg/kg) was orally administered for 1 h before a single intratracheal administration of lipopolysaccharide (LPS, 5 mg/kg). MGIIIE treatment dose‐dependently suppressed pulmonary oedema, pro‐inflammatory mediators (IL‐1β, IL‐6, TNF‐α and HMGB1) release and higher MPO activity in lung tissues induced by LPS challenge. Molecular researches showed that mogroside IIIE (20 mg/kg) not only increased the phosphorylation of adenosine 5′‐monophosphate‐activated protein kinase (AMPK) but suppressed the over‐expression of toll‐like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88). In addition, MGIIIE also inhibited the activation of MAPKs and nuclear factor κB (NF‐κB) signalling in lung tissues from LPS‐challenged mice. Similar antiinflammatory effects of MGIIIE were obtained in LPS‐treated macrophages. Compound C (a pharmacological AMPK inhibitor) obviously reversed the antiinflammatory effect of MGIIIE in LPS‐induced ALI mice. Taken together, AMPK activation plays a crucial role in the antiinflammatory effects of MGIIIE in LPS‐induced ALI by down‐regulating TLR4/MAPK/NF‐κB signalling pathways. Copyright © 2017 John Wiley & Sons, Ltd.     

Retracted: Lipopolysaccharides‐mediated injury to chondrogenic ATDC5 cells can be relieved by Sinomenine via downregulating microRNA‐192

Sinomenine (SIN) is an isoquinoline derived from Caulis Sinomenii that has been used to treat rheumatoid arthritis and osteoarthritis for several decades in China. This study aims to reveal the effects of SIN on mouse chondrogenic ATDC5 cells growth and inflammation. SIN was used to treat ATDC5 cells injured by lipopolysaccharides (LPS). The following parameters were determined for evaluating the treatment effects of SIN: cell viability, apoptosis, reactive oxygen species generation, and pro‐inflammatory cytokines release. Besides, the expression of LPS‐sensitive miRNA (miR‐192) and the activation of NF‐κB and MAPK signaling were studied to explain SIN's function. SIN with concentration of 30 μM significantly attenuated LPS‐induced cell damage via increasing cell viability, inhibiting apoptosis and reactive oxygen species generation, and declining IL‐6 and TNF‐α release. miR‐192 was downregulated by SIN treatment. Restoration of miR‐192 expression by miRNA transfection could significantly impede SIN's protective action. Besides, the inhibitory effects of SIN on the activation of NF‐κB and MAPK signaling were attenuated by miR‐192 overexpression. Furthermore, GDF11 was found to be a target gene of miR‐192. LPS‐mediated injury to chondrogenic ATDC5 cells can be relieved by SIN via downregulating miR‐192 and subsequently repressing the activation of NF‐κB and MAPK signaling.     

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.     

Astragalus polysaccharides exerts anti‐infective activity by inducing human cathelicidin antimicrobial peptide LL‐37 in respiratory epithelial cells

Astragalus polysaccharides (APS), one of the major active components in Astragalus membranaceus, is an effective immunomodulator used in the treatment of immunological diseases in China. However, the anti‐infective action and mechanism of APS is not fully known. In the present study, we found that APS induced the expression of human cathelicidin antimicrobial peptide LL‐37, a key host anti‐infective molecule, in both mRNA and protein levels in respiratory epithelial cells HBE16 and A549. Furthermore, the lysate and supernatant from APS‐treated HBE16 cells both exhibited an obvious antibacterial action, which was partially neutralizated by LL‐37 monoclonal antibody. In addition, APS also significantly elevated the phosphorylation of p38 MAPK and JNK and caused the degradation of IκBα. Specific inhibitors of p38 MAPK, JNK, or NF‐κB obviously abolished APS‐induced LL‐37 synthesis and antibacterial activity, respectively. Taken together, our results confirmed the enhancement of APS on LL‐37 induction and antibacterial action in respiratory epithelial cells, which may be attributed to activation of p38 MAPK/JNK and NF‐κB pathways. Furthermore, these results also supported the clinical application of APS in the treatment of infectious diseases.     

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.     

Schisandra chinensis ameliorates depressive‐like behaviors by regulating microbiota‐gut‐brain axis via its anti‐inflammation activity

The present study aimed to examine the antidepressant actions of the composition fractions of Schisandra chinensis using LPS‐induced mice. Animals were treated with total extracts (SCE), lignans (SCL), polysaccharides (SCPS), and essential oil (SCVO), and then subjected to behavioral tests. The forced swimming test (FST) and tail suspension test (TST) were used as predictive animal models of antidepressant activity. Total extracts and lignans significantly decreased the duration of immobility in FST and TST. We found that treatment with SCE and SCL could significantly decrease the levels of pro‐inflammatory cytokines both in the periphery and central nervous system (CNS). This was confirmed by the histopathological examination of the colon. The RT‐PCR results demonstrated that SCE and SCL could greatly inhibit the TLR4/NF‐κB/IKKα signaling pathway. In addition, the concentrations of Butyric acid and Propionic acid were upregulated by the administration, and the decreased diversity of intestinal microbiota and alterations of the relative proportions of Bacteroidetes and Firmicutes phylum members, Barnesiella and Lactobacillus genus members in LPS‐induced mice were restored as well. All results suggested that lignans is the effective fraction of S.chinensis to ameliorating depressive disorders, which its anti‐inflammation activity possibly involved in the bidirectional connection between gut microbiota and brain.     

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.