辛伐他汀对肿瘤坏死因子α诱导CX3CL1表达的影响

目的通过研究辛伐他汀对肿瘤坏死因子(TNF)-α诱导血管平滑肌细胞CX3CLl表达的影响,进一步探讨辛伐他汀的抗炎机制。方法采用体外培养的SD大鼠血管平滑肌细胞;免疫荧光法检测核因子(NF)-κB的活化;RT-PCR法检测CX3CLl mRNA表达。结果 TNF-α可诱导血管平滑肌细胞NF-κB活化,并增加CX3CLlmRNA的表达;辛伐他汀可抑制TNF-α对血管平滑肌细胞NF-κB活化及CX3CLl mRNA的表达。结论辛伐他汀可能通过抑制NF-κB的活化,而下调TNF-α诱导的CX3CLl的表达。     

Inhibitory effects of PPAR-γ on endothelin-1-induced inflammatory pathways in vascular smooth muscle cells from normotensive and hypertensive rats

The present study evaluated the effects of endothelin (ET)-1 and the peroxisome proliferator activated receptor γ (PPAR-γ) agonist, rosiglitazone, on inflammatory markers in vascular smooth muscle cells (VSMCs) from normotensive (WKY) and hypertensive (SHRSP) rats. Rat VSMC-derived mesenteric arteries from WKY and SHRSP were treated with ET-1 (100 mmol/L) and rosiglitazone (1μmol/L) or ET type A (ET_A) or type B (ET_B) receptor antagonists. Nuclear factor kappa-B (NFκB) binding activity was assessed by electrophoretic mobility shift assay and phospho-inhibitory κB (IκB); vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, and cyclooxygenase (COX)-2 expression was determined using Western blotting. ET-1 significantly increased NFκB binding, and VCAM-1, ICAM, and COX-2 expression to a greater degree in SHRSP than in WKY VSMC. These changes were associated with increased phosphorylation of IκB, thus resulting in decreased NFκB inhibition. Co-incubation with PPAR-γ activator rosiglitazone, or ET_A or ET_B receptor antagonism prevented ET-1-stimulated vascular proinflammatory effects in both WKY and SHRSP VSMC. Proinflammatory effects of ET-1 in VSMCs are mediated via both ET_A and ET_B receptor subtypes. These effects may be abrogated by the PPAR-γ activator rosiglitazone. PPAR-γ activators may thus prevent deleterious ET-1-dependent proinflammatory vascular effects in VSMC in hypertension.     

Resveratrol, a polyphenolic phytostilbene, inhibits endothelial monocyte chemotactic protein-1 synthesis and secretion

BACKGROUND/AIMS: Resveratrol is a naturally occurring polyphenol phytoestrogen and one of several constituents of red wine thought to be cardioprotective. We investigated the effect of resveratrol on the expression of the atherogenic chemokine, monocyte chemotactic protein-1 (MCP-1). METHODS: Human umbilical vein endothelial cells were stimulated with interleukin-1beta (IL-1beta) in the absence or presence of resveratrol. MCP-1 levels were determined by ELISA and MCP-1 mRNA was measured. RESULTS: Resveratrol (1-100 microM) dose-dependently inhibited IL-1beta-stimulated MCP-1 secretion, with approximately 45% inhibition at 50 microM resveratrol. This was a Gi-protein- and NO-dependent effect. Resveratrol also significantly inhibited MCP-1 gene expression in a Gi-protein-dependent but NO-independent manner. While resveratrol had no effect on MCP-1 mRNA degradation, it inhibited MCP-1 promoter activity and reduced nuclear factor kappaB and activator protein-1 binding activity induced by IL-1beta. Moreover, while hemoxygenase-1 (HO-1) expression was induced by resveratrol in human umbilical vein endothelial cells, neither treatment with the HO-1 inhibitor tin-protoporphyrin IX nor siRNA-directed knockdown of HO-1 had any effect on the inhibition of MCP-1 mRNA or protein secretion by resveratrol. CONCLUSION: These data demonstrate an inhibitory effect of resveratrol on MCP-1 synthesis and secretion, mediated via distinct signaling pathways. The inhibition of MCP-1 may represent a novel cardioprotective mechanism of resveratrol.     

Immunoglobulin light chains activate nuclear factor-κB in renal epithelial cells through a Src-dependent mechanism

One of the major attendant complications of multiple myeloma is renal injury, which contributes significantly to morbidity and mortality in this disease. Monoclonal immunoglobulin free light chains (FLCs) are usually directly involved, and tubulointerstitial renal injury and fibrosis are prominent histologic features observed in myeloma. The present study examined the role of monoclonal FLCs in altering the nuclear factor κ light chain enhancer of activated B cells (NF-κB) activity of renal epithelial cells. Human proximal tubule epithelial cells exposed to 3 different human monoclonal FLCs demonstrated Src kinase-dependent activation of the NF-κB pathway, which increased production of monocyte chemoattractant protein-1 (MCP-1). Tyrosine phosphorylation of inhibitor of κB kinases (IKKs) IKKα and IKKβ and a concomitant increase in inhibitor of κB (IκB) kinase activity in cell lysates were observed. Time-dependent, Src kinase-dependent increases in serine and tyrosine phosphorylation of IκBα and NF-κB activity were also demonstrated. Proteasome inhibition partially blocked FLC-induced MCP-1 production. These findings fit into a paradigm characterized by FLC-induced redox-signaling events that activated the canonical and atypical (IKK-independent) NF-κB pathways to promote a proinflammatory, profibrotic renal environment.     

Resveratrol and Diabetes

Resveratrol is a stilbene compound, and a phytoalexin, synthesized by plants in response to stressful stimuli, usually caused by infection. It is abundantly present in red wine, ports and sherries, red grapes, blueberries, peanuts, itadori tea, as well as hops, pistachios, and in grape and cranberry juices. The anti-hyperglycemic effects of resveratrol seem to be the result of an increased action of the glucose transporter in the cytoplasmic membrane. Studies on rats with streptozotocin-induced diabetes have demonstrated that the expression of the insulin-dependent glucose transporter, GLUT4, is increased after resveratrol ingestion. Also, resveratrol enhances adiponectin levels, which could be one of the potential mechanisms by which it improves insulin sensitivity. Another important observation is that resveratrol induces the secretion of the gut incretin hormone, glucagon-like peptide-1. Resveratrol is also reported to activate Sir2 (silent information regulatory 2), a SIRT1 homolog, thus mimicking the benefits of calorie restriction. It produces a wide variety of effects in mammalian cells, including activation of AMP-activated protein kinase, which is involved in some of the same metabolic pathways as SIRT1, which may influence other mechanisms via the involvement of nuclear factor kappa B (NF-κB). In the near future, resveratrol-based therapies with either resveratrol or its analogs that have better bioavailability could be useful in the treatment of diabetes and its complications, either alone or in combination with other anti-diabetic drugs.     

白藜芦醇对单核细胞表达CC类趋化因子受体2基因和内皮细胞分泌单核细胞趋化蛋白1的影响

目的 探讨白藜芦醇对活化的人脐静脉内皮细胞分泌单核细胞趋化蛋白1及对人单核细胞株THP-1细胞表面CC类趋化因子受体2基因表达的影响.方法 半定量逆转录聚合酶链反应法检测THP-1细胞CC类趋化因子受体2 mRNA的表达;以肿瘤坏死因子α激活人脐静脉内皮细胞,酶联免疫吸附法测定活化的人脐静脉内皮细胞单核细胞趋化蛋白1的分泌.结果 10 μmol/L和50 μmol/L白藜芦醇可以抑制THP-1细胞CC类趋化因子受体2 mRNA的表达(0.19±0.02和0.06±0.02比0.73±0.15,P<0.01),且随着白藜芦醇剂量的升高(1、10、50 μmol/L),基因表达抑制也逐渐加强(P<0.01);10 μmol/L和50μmol/L白藜芦醇可减少活化的人脐静脉内皮细胞单核细胞趋化蛋白1的分泌(9 663.33±927.38 ng/L和2 822.17±472.47 ng/L比16 595.67 ±1 667.39 ng/L,P<0.01),随着白藜芦醇剂量升高,单核细胞趋化蛋白1分泌逐渐减少(P<0.01).结论 白藜芦醇能剂量依赖性地抑制单核细胞CC类趋化因子受体2基因的表达,并减少活化的内皮细胞单核细胞趋化蛋白1的分泌,从而有效抑制单核细胞的趋化,发挥抗动脉粥样硬化的作用.     

NOD2 activation induces muscle cell-autonomous innate immune responses and insulin resistance

Insulin resistance is associated with chronic low-grade inflammation in vivo, largely mediated by activated innate immune cells. Cytokines and pathogen-derived ligands of surface toll-like receptors can directly cause insulin resistance in muscle cells. However, it is not known if intracellular pathogen sensors can, on their own, provoke insulin resistance. Here, we show that the cytosolic pattern recognition receptors nucleotide-binding oligomerization domain-containing protein (NOD)1 and NOD2 are expressed in immune and metabolic tissues and hypothesize that their activation in muscle cells would result in cell-autonomous responses leading to insulin resistance. Bacterial peptidoglycan motifs that selectively activate NOD2 were directly administered to L6- GLUT4myc myotubes in culture. Within 3 h, insulin resistance arose, characterized by reductions in each insulin-stimulated glucose uptake, GLUT4 translocation, Akt Ser(473) phosphorylation, and insulin receptor substrate 1 tyrosine phosphorylation. Muscle cell-autonomous responses to NOD2 ligand included activation of the stress/inflammation markers c-Jun N-terminal kinase, ERK1/2, p38 MAPK, degradation of inhibitor of κBα, and production of proinflammatory cytokines. These results show that NOD2 alone is capable of acutely inducing insulin resistance within muscle cells, possibly by activating endogenous inflammatory signals and/or through cytokine production, curbing upstream insulin signals. NOD2 is hence a new inflammation target connected to insulin resistance, and this link occurs without the need of additional contributing cell types. This study provides supporting evidence for the integration of innate immune and metabolic responses through the involvement of NOD proteins and suggests the possible participation of cell autonomous immune responses in the development of insulin resistance in skeletal muscle, the major depot for postprandial glucose utilization.     

Resveratrol via activation of AMPK lowers blood pressure in DOCA-salt hypertensive mice

Abstract

Objective: Resveratrol, a phytoalexin, is reported to activate AMP-activated protein kinase (AMPK) in vascular cells. Activation of AMPK induces vasorelaxation to lower blood pressure (BP). Whether resveratrol via activation of AMPK decreases, BP remains unknown. Methods: Male wild-type (WT) mice and mice deficient in AMPKα2 (AMPKα2^?/?) were fed with resveratrol (400?mg/kg). After 7?d, mice were implanted with deoxycorticosterone acetate (DOCA)-salt (150?mg/kg) for 35?d. BP was detected by the radiotelemetry method. Vessel contraction was determined by organ chamber. Active RhoA, Rho-associated kinase (ROCK) activity, phosphorylations of myosin light chain (MLC), and myosin phosphatase targeting subunit 1 (MYPT1) were assayed by western blot. Results: Implantation of DOCA-salt dramatically increased systemic BPs (systolic BP and diastolic BP) in WT and AMPKα2^?/? mice. However, treatment of resveratrol significantly decreased systemic BP in WT mice but not in AMPKα2^?/? mice. In the organ chamber study, resveratrol inhibited agonist-induced vessel relaxation in WT mice aortas. Loss of AMPKα2 or AMPK inhibition by compound C reversed resveratrol-suppressed vasoconstriction in isolated mice aortas. In cultured vascular smooth muscle cells (VSMCs), activation of AMPK by resveratrol inhibited phenylephrine-enhanced MLC phosphorylation in a dose-dependent manner. Conclusions: Resveratrol via activation of AMPK lowers BP in DOCA-hypertensive mice through an AMPK/RhoA/ROCK2/MLCMLC pathway.     

Fetuin-A influences vascular cell growth and production of proinflammatory and angiogenic proteins by human perivascular fat cells

Aims/hypothesis

Fetuin-A (alpha2-Heremans-Schmid glycoprotein), a liver-derived circulating glycoprotein, contributes to lipid disorders, diabetes and cardiovascular diseases. In a previous study we found that perivascular fat cells (PVFCs) have a higher angiogenic potential than other fat cell types. The aim was to examine whether fetuin-A influences PVFC and vascular cell growth and the expression and secretion of proinflammatory and angiogenic proteins, and whether TLR4-independent pathways are involved.

Methods

Mono- and co-cultures of human PVFCs and endothelial cells were treated with fetuin-A and/or palmitate for 6–72 h. Proteins were quantified by ELISA and Luminex, mRNA expression by real-time PCR, and cell growth by BrDU-ELISA. Some PVFCs were preincubated with a nuclear factor κB NFκBp65 inhibitor, or the toll-like receptor 4 (TLR4) inhibitor CLI-095, or phosphoinositide 3-kinase (PI3K)/Akt inhibitors and/or stimulated with insulin. Intracellular forkhead box protein O1 (FoxO1), NFκBp65 and inhibitor of κB kinase β (IKKβ) localisation was visualised by immunostaining.

Results

PVFCs expressed and secreted IL-6, IL-8, plasminogen activator inhibitor 1 (PAI-1), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-BB, monocyte chemotactic protein-1 (MCP-1), vascular endothelial growth factor (VEGF), placental growth factor (PLGF) and hepatocyte growth factor (HGF). Fetuin-A upregulated IL-6 and IL-8, and this was potentiated by palmitate and blocked by CLI-095. Immunostaining and electrophoretic mobility shift assay (EMSA) showed partial NFκBp65 activation. MCP-1 was upregulated and blocked by CLI-095, but not by palmitate. However, HGF was downregulated, which was slightly potentiated by palmitate. This effect persisted after TLR4 pathway blockade. Stimulation of insulin–PI3K–Akt signalling by insulin resulted in nuclear FoxO1 extrusion and HGF upregulation. Fetuin-A counteracted these insulin effects.

Conclusions/interpretation

Fetuin-A and/or palmitate influence the expression of proinflammatory and angiogenic proteins only partially via TLR4 signalling. HGF downregulation seems to be mediated by interference with the insulin-dependent receptor tyrosine kinase pathway. Fetuin-A may also influence angiogenic and proinflammatory proteins involved in atherosclerosis.     

Resveratrol: Effects on Lipids and Cardiovascular Risk

For several decades, there has been increasing interest in the possible use of resveratrol as a preventative agent in cardiovascular disease. Resveratrol exerts numerous effects on adipocyte, hepatocyte, and endothelial cell development and function. Many investigations have demonstrated the ability of resveratrol to regulate the adipocyte lifecycle, lipid synthesis, and improve hepatic lipid metabolism. Resveratrol has numerous vascular protective effects on endothelial tissue, including its antiplatelet activity. Resveratrol also reduces intracellular oxidative stress. Animal models of obesity and cardiovascular diseases have yielded important contributions to our understanding of the effects of resveratrol on the vasculature and the risk for pathology. In limited human studies, resveratrol reduces the release of proinflammatory cytokines and improves systemic glucose and insulin regulation and decreases cellular oxidative stress. Therefore, resveratrol has significant potential as both a prophylactic and treatment agent. However additional studies are required to more completely characterize its impacts on human physiology and its benefits in the setting of disease.     

Receptor for advanced glycation endproducts signaling cascades are activated in pancreatic fibroblasts,but not in the INS1E insulinoma cell line: Are mesenchymal cells major players in chronic inflammation?

The receptor for advanced glycation endproducts (RAGE) is a pattern recognition receptor that plays an important role in natural immunity. It is suggested that mesenchymal cells are the major players during inflammation. Previously, we reported that advanced glycation end products (AGE), known to be one of the ligands of RAGE, inhibited glucose-induced insulin secretion from ex vivo pancreatic islets, although the mechanism responsible remains largely unknown. In the present study, we examined the cascades operating downstream from RAGE using the insulinoma cell line INS1E and primary-cultured pancreatic fibroblasts as in vitro models for parenchymal (β) cells and mesenchymal cells, respectively. Phosphorylation of c-jun N-terminal kinase, inhibitor of nuclear factor κB kinase, and nuclear factor κB was stimulated by AGE or high mobility group binding 1 (HMGB1) in pancreatic fibroblasts, whereas no such effect was observed in INS1E cells. Expression of the Ccl5, Il-6, and Il-1b genes was increased by AGE/HMGB1 in fibroblasts, but not in INS1E cells. On the other hand, AGE inhibited the secretion of insulin from ex vivo pancreatic islets, and this effect was ameliorated by MK615, a Japanese apricot extract used as an anti-inflammatory agent. Glucose-induced insulin secretion from INS1E cells was not affected by direct administration of AGE/HMGB1, but was inhibited by fibroblast-conditioned medium. These results suggest that AGE suppresses glucose-induced insulin secretion from pancreatic islets through indirect mesenchymal RAGE signaling.