The novel protective effects of loganin against 1‐methyl‐4‐phenylpyridinium‐induced neurotoxicity: Enhancement of neurotrophic signaling,activation of IGF‐1R/GLP‐1R,and inhibition of RhoA/ROCK pathway

Loganin, a major iridoid glycoside obtained from fruits of Cornus officinalis, possesses anti‐inflammatory, antitumor, antidiabetic, and osteoporosis prevention effects. Loganin has been linked to neuroprotection in several models of neurodegeneration, including Parkinson's disease (PD). However, mechanisms underlying the neuroprotective effects of loganin are still mostly unknown. Here, we demonstrated the protective effects of loganin against PD mimetic toxin 1‐methyl‐4‐phenylpyridinium (MPP⁺) and the important roles of insulin‐like growth factor 1 receptor (IGF‐1R) and glucagon‐like peptide 1 receptor (GLP‐1R) in the neuroprotective mechanisms of loganin. In primary mesencephalic neuronal cultures treated with or without MPP⁺, loganin up‐regulated expressions of neurotrophic signals including IGF‐1R, GLP‐1R, p‐Akt, BDNF, and tyrosine hydroxylase. Loganin protected against MPP⁺‐induced apoptosis by up‐regulating antiapoptotic protein and down‐regulating proapoptotic protein. Moreover, loganin attenuated MPP⁺‐induced neurite damage via up‐regulation of GAP43 and down‐regulation of membrane‐RhoA/ROCK2/p‐LIMK/p‐cofilin. Loganin also attenuated MPP⁺‐induced reactive oxygen species (ROS) production. However, both AG1024, an IGF‐1R antagonist, and exendin 9‐39, a GLP‐1R antagonist, attenuated the protective effects of loganin on MPP⁺‐induced cytotoxicity, apoptosis, neurite length decrease, and ROS production. Our results suggest that loganin attenuates MPP⁺‐induced apoptotic death, neurite damage, and oxidative stress through enhancement of neurotrophic signaling, activation of IGF‐1R/GLP‐1R, and inhibition of RhoA/ROCK pathway, providing the evidence that loganin possesses novel neuroprotective effects.     

Hesperidin ameliorates insulin resistance by regulating the IRS1‐GLUT2 pathway via TLR4 in HepG2 cells

The aim of this study was to evaluate the effect and mechanism of hesperidin (HES) on insulin resistance (IR) in the human hepatocellular carcinoma cell line (HepG2 cells). HepG2 cells were induced with lipopolysaccharide (LPS) as a model of IR and treated with HES at three dosages. Next, the levels of interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α), the glucose content, and glucose uptake were evaluated by enzyme‐linked immunosorbent assay, glucose oxidase‐peroxidase method (GOD‐POD), or (2‐(N‐(7‐nitrobenz‐2‐oxa‐1, 3‐diazol‐4‐yl)amino)‐2‐deoxyglucose) (2‐NBDG). Moreover, the protein expression of toll‐like receptors 4 (TLR4), insulin receptor substrate 1 (IRS1), nuclear factor kappa B (NF‐κB), and glucose transporter 2 (GLUT2) in HepG2 cells treated with HES were assessed via western blotting analysis. In addition, GLUT2 protein expression exposed to HES was detected following treatment with TLR4 inhibitor (HTA125). Our results demonstrated that HES decreased the levels of TNF‐α and IL‐6, attenuated the glucose content in culture medium and increased glucose uptake in insulin‐resistant HepG2 cells in vitro. Moreover, HES upregulated the expression of IRS1 and GLUT2 protein and downregulated the protein expression of TLR4 and NF‐κB in insulin‐resistant HepG2 cells. The expression of GLUT2 protein had no significant changes when treated with HES after blockade of TLR4. HES attenuated IR in LPS‐inducedinsulin‐resistant HepG2 cells. Therefore, regulating the IRS1‐GLUT2 pathway via TLR4 represents a potential mechanism of HES on IR in HepG2 cells.     

Inhibition of LPS‐Induced TNF‐α and NO Production in Mouse Macrophage and Inflammatory Response in Rat Animal Models by a Novel Ayurvedic Formulation,BV‐9238

Rheumatoid arthritis is a chronic crippling disease, where protein‐based tumor necrosis factor‐alpha (TNF‐α) inhibitors show significant relief, but with potentially fatal side effects. A need for a safe, oral, cost‐effective small molecule or phyto‐pharmaceutical is warranted. BV‐9238 is an Ayurvedic poly‐herbal formulation containing specialized standardized extracts of Withania somnifera, Boswellia serrata, Zingiber officinale and Curcuma longa. The anti‐inflammatory and anti‐arthritic effects of BV‐9238 were evaluated for inhibition of TNF‐α and nitric oxide (NO) production, in lipopolysaccharide‐stimulated, RAW 264.7, mouse macrophage cell line. BV‐9238 reduced TNF‐α and NO production, without any cytotoxic effects. Subsequently, the formulation was tested in adjuvant‐induced arthritis (AIA) and carrageenan‐induced paw edema (CPE) rat animal models. AIA was induced in rats by injecting Freund's complete adjuvant intra‐dermally in the paw, and BV‐9238 and controls were administered orally for 21 days. Arthritic scores in AIA study and inflamed paw volume in CPE study were significantly reduced upon treatment with BV‐9238. These results suggest that the anti‐inflammatory and anti‐arthritic effects of BV‐9238 are due to its inhibition of TNF‐α, and NO, and this formulation shows promise as an alternate therapy for inflammatory disorders where TNF‐α and NO play important roles. Copyright © 2014 John Wiley & Sons, Ltd.     

Ramalin Isolated from Ramalina Terebrata Attenuates Atopic Dermatitis‐like Skin Lesions in Balb/c Mice and Cutaneous Immune Responses in Keratinocytes and Mast Cells

Atopic dermatitis (AD) is a chronic inflammatory skin disease that involves eczematous skin lesions with pruritic erythematous papules. In this study, we investigated the mitigating effects of ramalin, a component of the Antarctic lichen Ramalina terebrata against AD in vivo and in vitro. Oral administration of ramalin lessened scratching behaviors and significantly reduced both serum immunoglobulin E and IL‐4 levels, and mRNA levels of IL‐4 and IL‐10 in AD‐induced Balb/c mice. In vitro, treatment with ramalin produced significantly less inflammatory chemokines and cytokines, including TARC, MCP‐1, RANTES, and IL‐8 in TNF‐α‐stimulated HaCaT cells. In addition, ramalin inhibited the activation of nuclear factor‐kappa B as well as the phosphorylation of mitogen‐activated protein kinases (MAPK). Furthermore, ramalin treatment resulted in decreased production of β‐hexosaminidase and proinflammatory cytokines IL‐4, IL‐6, and TNF‐α in 2,4 dinitrophenyl‐human serum albumin‐stimulated RBL‐2H3 cells through blocking MAPK signaling pathways. The results suggest that ramalin modulates the production of immune mediators by inhibiting the nuclear factor‐kappa B and MAPK signaling pathways. Taken together, ramalin effectively attenuated the development of AD and promoted the mitigating effects on Th2 cell‐mediated immune responses and the production of inflammatory mediators in mast cells and keratinocytes. Thus, ramalin may be a potential therapeutic agent for AD. Copyright © 2016 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.     

Myrislignan Attenuates Lipopolysaccharide‐induced Inflammation Reaction in Murine Macrophage Cells Through Inhibition of NF‐κB Signalling Pathway Activation

Myrislignan is a new kind of lignan isolated from Myristica fragrans Houtt. Its antiinflammatory effects have not yet been reported. In the present study, the antiinflammatory effects and the underlying mechanisms of myrislignan in lipopolysaccharide (LPS)‐induced inflammation in murine RAW 264.7 macrophage cells were investigated. Myrislignan significantly inhibited LPS‐induced production of nitric oxide (NO) in a dose‐dependent manner. It inhibited mRNA expression and release of interleukin‐6 (IL‐6) and tumour necrosis factor‐α (TNF‐α). This compound significantly inhibited mRNA and protein expressions of inducible NO synthase (iNOS) and cyclooxygenase‐2 (COX‐2) dose‐dependently in LPS‐stimulated macrophage cells. Further study showed that myrislignan decreased the cytoplasmic loss of inhibitor κB‐α (IκB‐α) protein and the translocation of NF‐κB from cytoplasm to the nucleus. Our results suggest that myrislignan may exert its antiinflammatory effects in LPS‐stimulated macrophages cells by inhibiting the NF‐κB signalling pathway activation. Copyright © 2012 John Wiley & Sons, Ltd.     

Sour Cherry Seed Kernel Extract Increases Heme Oxygenase‐1 Expression and Decreases Representation of CD3+ TNF‐α + and CD3 + IL‐8+ Subpopulations in Peripheral Blood Leukocyte Cultures from Type 2 Diabetes Patients

The present study evaluates a hypothesis that sour cherry (Prunus cerasus) seed extracts (SCE) modulate CD3+ T lymphocyte activity in ways predictive of potential for uses of SCE in management of inflammatory diseases. Peripheral blood mononuclear cells (PBMC) from 12 type 2 diabetes (T2DM) patients and eight healthy control subjects were cultured 24 h with 100 ng/ml lipopolysaccharide (LPS) to increase inflammatory signaling and co‐incubated with 0.5–100 µg/ml SCE. Cultures were evaluated by two‐color flow cytometry for percent representation of CD3+ IL8+ and CD3 + TNF‐α + cells which express interleukin‐8 (IL‐8), and tumor necrosis factor‐α, (TNF‐α+) respectively, and by enzyme‐linked immunoassay for lymphocyte‐associated heme oxygenase‐1 (HO‐1, known to be induced by SCE). SCE dosage ranges of 0.5–100 µg/ml in cell cultures significantly suppressed LPS‐increased CD3 + TNF‐α + and CD3 + IL8+ representation from all participants (p < 0.05), with greater pharmacological effect noted in suppression of CD3 + TNF‐α + noted in cells from T2DM patients versus healthy control subjects. These effects correlated with increased HO‐1 expression in SCE‐treated PBMC from all subjects (p < 0.05). Since TNF‐α and IL‐8 are diagnostic/prognostic biomarkers for many inflammatory syndromes, the capacity of SCE to down‐regulate representation of cells that express them suggests potential for therapeutic use of SCE in T2DM and other diseases. Copyright © 2012 John Wiley & Sons, Ltd.     

Nimbolide Inhibits Nuclear Factor‐КB Pathway in Intestinal Epithelial Cells and Macrophages and Alleviates Experimental Colitis in Mice

Nimbolide is a limonoid extracted from neem tree (Azadirachta indica) that has antiinflammatory properties. The effect of nimbolide on the nuclear factor‐kappa B (NF‐κB) pathway in intestinal epithelial cells (IECs), macrophages and in murine colitis models was investigated. The IEC COLO 205, the murine macrophage cell line RAW 264.7, and peritoneal macrophages from interleukin‐10‐deficient (IL‐10^?/?) mice were preconditioned with nimbolide and then stimulated with tumor necrosis factor‐α (TNF‐α) or lipopolysaccharide. Dextran sulfate sodium‐induced acute colitis model and chronic colitis model in IL‐10^?/? mice were used for in vivo experiments. Nimbolide significantly suppressed the expression of inflammatory cytokines (IL‐6, IL‐8, IL‐12, and TNF‐α) and inhibited the phosphorylation of IκBα and the DNA‐binding affinity of NF‐κB in IECs and macrophages. Nimbolide ameliorated weight loss, colon shortening, disease activity index score, and histologic scores in dextran sulfate sodium colitis. It also improved histopathologic scores in the chronic colitis of IL‐10^?/? mice. Staining for phosphorylated IκBα was significantly decreased in the colon tissue after treatment with nimbolide in both models. Nimbolide inhibits NF‐κB signaling in IECs and macrophages and ameliorates experimental colitis in mice. These results suggest nimbolide could be a potentially new treatment for inflammatory bowel disease. Copyright © 2016 John Wiley & Sons, Ltd.     

Anti-inflammatory effects of Polygala tenuifolia root through inhibition of NF-κB activation in lipopolysaccharide-induced BV2 microglial cells

Ethnopharmacological relevance

The root of Polygala tenuifolia Willd is a well-known traditional Oriental medicine and has been prescribed for treatment of dysfunction in memorial systems and various brain inflammatory diseases. The present study was designed to validate the anti-inflammatory effects of the water extract of Polygala tenuifolia root (WEPT).

Materials and methods

The anti-inflammatory properties of WEPT were studied using lipopolysaccharide (LPS)-stimulated murine BV2 microglia model. As inflammatory parameters, the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β were evaluated. We also examined the extract's effect on the activity of nuclear factor-kappaB (NF-κB), and toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (Myd-88) expression.

Results

WEPT suppressed LPS-induced production of NO, PGE₂, and expression of iNOS and COX-2 in a dose-dependent manner, without causing cytotoxicity. It also significantly reduced generation of proinflammatory cytokines, including IL-1β and TNF-α. In addition, WEPT suppressed NF-κB translocation by blockade of IkappaB-α (IκB-α) degradation and inhibited TLR4 and Myd-88 expression in LPS-stimulated BV2 cells.

Conclusions

These results indicate that the inhibitory effects of WEPT on LPS-stimulated inflammatory mediator production in BV2 microglia are associated with suppression of the NF-κB and toll-like receptor signaling pathways. Therefore, Polygala tenuifolia extracts may be useful in treatment of neurodegenerative diseases by inhibition of inflammatory mediator production in activated microglia.     

Korean red ginseng decreases 1-methyl-4-phenylpyridinium-induced mitophagy in SH-SY5Y cells

ObjectiveMitophagy is known to contribute towards progression of Parkinson’s disease. Korean red ginseng (KRG) is a widely used medicinal herb in East Asia, and recent studies have reported that KRG prevents 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced cell death. This study was undertaken to investigate whether KRG suppresses MPP⁺-induced apoptosis and mitophagy.MethodsSH-SY5Y cells were incubated with KRG for 24 h, and subsequently exposed to MPP⁺. The MPP⁺-induced cell death was confirmed with the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Changes in the structure and function of mitochondria were confirmed using mitotracker, MitoSOX red mitochondrial superoxide indicator, parkin, and phosphatase and tensin homolog deleted on chromosome ten-induced putative kinase 1 (PINK1) immunofluorescent staining. Western blotting was performed to evaluate the expression of apoptosis-related factors in whole cells, including Bax, Bcl-2 and cleaved caspase-3, and mitophagy-related factors in the mitochondrial fraction, including cytochrome c, parkin, PINK1, translocase of the outer membrane 20 (TOM20), p62 and Beclin 1.ResultsMPP⁺ induced cell death by cytochrome c release and caspase-3 activation; however, this effect was suppressed by KRG’s regulation of the expressions of Bcl-2 and Bax. Moreover, MPP⁺ exposure increased the mitochondrial expressions of parkin, PINK1, Beclin 1 and p62, and decreased TOM20, cytochrome c and Bcl-2 expressions. These MPP⁺-induced changes in the mitochondrial fraction were attenuated by treatment with KRG.ConclusionKRG effectively prevents MPP⁺-induced SH-SY5Y cell death by regulating cytochrome c release from mitochondria and PINK1/parkin-mediated mitophagy, through regulation of the Bcl-2 family.     

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.     

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.     

Effects of Crataegus microphylla on Vascular Dysfunction in Streptozotocin‐induced Diabetic Rats

Vascular dysfunction plays a key role in the pathogenesis of diabetic vascular disease. In this study, we aimed to investigate whether chronic in vivo treatment of Crataegus microphylla (CM) extract in diabetic rats induced with streptozotocin (STZ, intraperitoneal, 65 mg/kg) preserves vascular function and to evaluate whether the reduction of inducible nitric oxide synthase (iNOS), proinflammatory cytokines, and lipid peroxidation mediates its mechanisms of action. Starting at 4 weeks of diabetes, CM extract (100 mg/kg) was administrated to diabetic rats for 4 weeks. In aortic rings, relaxation to acetylcholine and vasoreactivity to noradrenaline were impaired, whereas aortic iNOS expression and plasma tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6), total nitrite–nitrate, and malondialdehite levels were increased in diabetic rats compared with controls. Chronic CM treatment significantly corrected all the above abnormalities in diabetic rats. In comparison, pretreatment of the aorta of diabetic rats with N‐[3(aminomethyl) benzyl]‐acetamidine, dihydrochloride (10^–5 M), a selective inhibitor of iNOS, produced a similar recovery in vascular reactivity. These results suggest that chronic in vivo treatment of CM preserves endothelium‐dependent relaxation and vascular contraction in STZ‐induced diabetes, possibly by reducing iNOS expression in the aorta and by decreasing plasma levels of TNF‐α and IL‐6 and by preventing lipid peroxidation. Copyright © 2012 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.     

Praeruptorin a inhibits lipopolysaccharide‐induced inflammatory response in murine macrophages through inhibition of NF‐κB pathway activation

Praeruptorin A (PA) is a pyranocoumarin compound isolated from the dried root of Peucedanum praeruptorum Dunn (Umbelliferae). However, the antiinflammatory effect of PA has not been reported. The present study investigated the antiinflammatory effect of PA in lipopolysaccharide (LPS)‐stimulated RAW 264.7 macrophage cells. PA significantly inhibited the LPS‐induced production of nitric oxide (NO), interleukin‐1β (IL‐1β) and tumor necrosis factor‐α (TNF‐α). The mRNA and protein expressions of inducible nitric oxide synthase (iNOS), IL‐1β and TNF‐α were also suppressed by this compound. Further study showed that PA decreased the cytoplasmic loss of inhibitor κB‐α (IκB‐α) protein and inhibited the translocation of NF‐κB from cytoplasm to nucleus. Taken together, the results suggest that PA may exert antiinflammatory effects in vitro in LPS‐stimulated RAW 264.7 macrophages through inhibition of NF‐κB signal pathway activation. Copyright © 2010 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.