Unfractionated heparin inhibits lipopolysaccharide-induced inflammatory response through blocking p38 MAPK and NF-κB activation on endothelial cell

Heparins, including unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH), are glycosaminoglycans that are largely used as anti-thrombotic drugs. While the mechanisms of their anticoagulant actions in blood have been extensively studied, their effects on the inflammation of the endothelium are still under investigation since the endothelium plays a central role in sepsis. Furthermore, UFH is much cheaper than LMWH. The aim of this study was to determine how UFH regulates lipopolysaccharide (LPS)-induced inflammatory response on endothelial cells in vitro, and define the role of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in mediating this effect. Human pulmonary microvascular endothelial cells (HPMECs) were pretreated with UFH (0.01U/ml-10U/ml), prior to stimulation with LPS (10μg/ml). Markers of systemic inflammation and endothelial activation were assessed. Interleukin (IL)-1β, IL-6, E-selectin, intercellular adhesion molecule (ICAM)-1 release were subsequently measured at 2h, 6h and 12h. Phosphorylation of p38 MAPK at 2h, 6h and nuclear translocation of the proinflammatory NF-κB at 2h were assessed. In HPMEC, UFH significantly attenuated LPS-induced production of IL-1β, IL-6, E-selectin and ICAM-1, as well as phosphorylation of p38 MAPK and NF-κB translocation, especially in 10U/ml. In conclusion, UFH at high dose significantly protects against endothelial-cell-mediated immune response. The inhibition of p38 MAPK and NF-κB activation certainly represents one of the mechanisms by which UFH exerts its anti-inflammatory effect.     

Aciculatin inhibits lipopolysaccharide-mediated inducible nitric oxide synthase and cyclooxygenase-2 expression via suppressing NF-κB and JNK/p38 MAPK activation pathways

Objectives  

Natural products have played a significant role in drug discovery and development. Inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) have been suggested to connect with various inflammatory diseases. In this study, we explored the anti-inflammatory potential of aciculatin (8-((2R,4S,5S,6R)-tetrahydro-4,5-dihydroxy-6-methyl-2H-pyran-2-yl)-5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one), one of main components of Chrysopogon aciculatis, by examining its effects on the expression and activity of iNOS and COX-2 in lipopolysaccharide (LPS)-activated macrophages.     

The plant limonoid 7-oxo-deacetoxygedunin inhibits RANKL-induced osteoclastogenesis by suppressing activation of the NF-κB and MAPK pathways

Osteoclasts together with osteoblasts play pivotal roles in bone remodeling. Aberrations in osteoclast differentiation and activity contribute to osteopenic disease. Osteoclasts differentiate from monocyte/macrophage progenitors, a process that is initiated by the interaction between receptor activator of NF-κB (RANK) and its ligand, RANKL. In this study, we identified 7-oxo-7-deacetoxygedunin (7-OG), a gedunin type limonoid from seeds of the mangrove Xylocarpus moluccensis, as a potent inhibitor of osteoclastogenesis. Additionally, 7-OG showed strong anti-osteoclastogenic activity with low cytotoxicity against the monocyte/macrophage progenitor cell line, RAW264.7. The IC50 for anti-osteoclastogenic activity was 4.14 μM. Treatment with 7-OG completely abolished the appearance of multinucleated giant cells with tartrate-resistant acid phosphatase activity in RAW264.7 cells stimulated with RANKL. When the expression of genes related to osteoclastogenesis was investigated, a complete downregulation of NFATc1 and cathepsin K and a delayed downregulation of irf8 were observed upon 7-OG treatment in the presence of RANKL. Furthermore, treatment with this limonoid suppressed RANKL-induced activation of p38, MAPK and Erk and nuclear localization of NF-κB p65. Taken together, we present evidence indicating a plant limonoid as a novel osteoclastogenic inhibitor that could be used for osteoporosis and related conditions.     

Uric acid stimulates proliferative pathways in vascular smooth muscle cells through the activation of p38 MAPK,p44/42 MAPK and PDGFRβ

Hyperuricemia and angiotensin II (Ang II) may have a pathogenetic role in the development of hypertension and atherosclerosis as well as cardiovascular disease (CVD) and its prognosis. The purpose of this study was to investigate whether uric acid can induce proliferative pathways of vascular smooth muscle cell (VSMC) that are thought to be responsible for the development of CVD. The phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), p44/42 mitogen-activated protein kinase (p44/42 MAPK) and platelet-derived growth factor receptor β (PDGFRβ) was measured by Elisa and Western blot techniques to determine the activation of proliferative pathways in primary cultured VSMCs from rat aorta. Results demonstrated that uric acid can stimulate p38 MAPK, p44/42 MAPK and PDGFRβ phosphorylation in a time- and concentration-dependent manner. Furthermore, treatment of VSMCs with the angiotensin II type I receptor (AT1R) inhibitor losartan suppressed p38 MAPK and p44/42 MAPK induction by uric acid. The stimulatory effect of uric acid on p38 MAPK was higher compared to that of Ang II. The results of this study show for the first time that uric acid-induced PDGFRβ phosphorylation plays a crucial role in the development of CVDs and that elevated uric acid levels could be a potential therapeutical target in CVD patients.     

oxHDL decreases the expression of CD36 on human macrophages through PPARγ and p38 MAP kinase dependent mechanisms

CD36, belongs to class B scavenger receptor family, is a macrophage receptor for oxidized low-density lipoprotein (oxLDL) and has been proven to play a critical role in atherosclerotic foam cell formation. In addition, CD36 expression is regulated by many factors including oxLDL and HDL. A recent study suggests that CD36 can also bind with oxidized high-density lipoprotein (oxHDL). However, the direct role of oxHDL in atherosclerosis is still not clear and it is not known whether oxHDL has any influence on the expression of CD36 in macrophages. Here, we performed experiments to investigate the effect of oxHDL on the expression of CD36 on human peripheral blood monocytes–macrophages and the possible mechanisms. Our results suggest that the uptake of oxHDL by CD36 on macrophages accelerates foam cell formation. In addition, oxHDL can down-regulate both the mRNA and surface protein expression of CD36 on human peripheral macrophages in vitro. oxHDL increased the mRNA expression and protein phosphorylation of peroxisome proliferators-activated receptor-γ (PPARγ). Using different mitogen-activated protein kinase (MAPK) inhibitors, we demonstrated that oxHDL regulated CD36 and PPARγ expression in a p38-MAP kinase dependent mechanism.     

Thrombin induces MCP-1 expression through Rho-kinase and subsequent p38MAPK/NF-κB signaling pathway activation in vascular endothelial cells

Thrombin has been shown to increase expression of chemokines such as monocyte chemoattractant protein 1 (MCP-1) in endothelial cells, leading to the development of atherosclerosis. However, the precise mechanism of this induction remains unknown. In the present study, we investigated whether the small G protein RhoA, and its effector, Rho-kinase are involved in MCP-1 induction by thrombin in endothelial cells. Y-27632, a specific Rho-kinase inhibitor, potently inhibited MCP-1 induction by thrombin. Y-27632 significantly decreased the chemotactic activity of thrombin-stimulated supernatants of endothelial cells on monocytes. Importantly, fasudil, a specific Rho-kinase inhibitor, attenuated MCP-1 gene expression in the aorta of db/db mice. Y-27632 attenuated thrombin-mediated phosphorylation of p38MAPK and p65, indicating that Rho-kinase mediates thrombin-induced MCP-1 expression through p38MAPK and NF-κB activation. Our findings demonstrate that the Rho/Rho-kinase signaling pathway plays a critical role in thrombin-mediated MCP-1 expression and function, and suggest that Rho/Rho-kinase may be an important target in the development of new therapeutic strategies for atherosclerosis.     

The p101 subunit of PI3Kγ restores activation by Gβ mutants deficient in stimulating p110γ

G-protein-regulated PI3Kγ (phosphoinositide 3-kinase γ) plays a crucial role in inflammatory and allergic processes. PI3Kγ, a dimeric protein formed by the non-catalytic p101 and catalytic p110γ subunits, is stimulated by receptor-released Gβγ complexes. We have demonstrated previously that Gβγ stimulates both monomeric p110γ and dimeric p110γ/p101 lipid kinase activity in vitro. In order to identify the Gβ residues responsible for the Gβγ-PI3Kγ interaction, we examined Gβ1 mutants for their ability to stimulate lipid and protein kinase activities and to recruit PI3Kγ to lipid vesicles. Our findings revealed different interaction profiles of Gβ residues interacting with p110γ or p110γ/p101. Moreover, p101 was able to rescue the stimulatory activity of Gβ1 mutants incapable of modulating monomeric p110γ. In addition to the known adaptor function of p101, in the present paper we show a novel regulatory role of p101 in the activation of PI3Kγ.     

Celastrol inhibits tumor cell proliferation and promotes apoptosis through the activation of c-Jun N-terminal kinase and suppression of PI3 K/Akt signaling pathways

Celastrol, a plant triterpene has attracted great interest recently, especially for its potential anti-inflammatory and anti-cancer activities. In the present report, we investigated the effect of celastrol on proliferation of various cancer cell lines. The mechanism, by which this triterpene exerts its apoptotic effects, was also examined in detail. We found that celastrol inhibited the proliferation of wide variety of human tumor cell types including multiple myeloma, hepatocellular carcinoma, gastric cancer, prostate cancer, renal cell carcinoma, head and neck carcinoma, non-small cell lung carcinoma, melanoma, glioma, and breast cancer with concentrations as low as 1 μM. Growth inhibitory effects of celastrol correlated with a decrease in the levels of cyclin D1 and cyclin E, but concomitant increase in the levels of p21 and p27. The apoptosis induced by celastrol was indicated by the activation of caspase-8, bid cleavage, caspase-9 activation, caspase-3 activation, PARP cleavage and through the down regulation of anti-apoptototic proteins. The apoptotic effects of celastrol were preceded by activation of JNK and down-regulation of Akt activation. JNK was needed for celastrol-induced apoptosis, and inhibition of JNK by pharmacological inhibitor abolished the apoptotic effects. Overall, our results indicate that celastrol can inhibit cell proliferation and induce apoptosis through the activation of JNK, suppression of Akt, and down-regulation of anti-apoptotic protein expression.     

Ischemic post-conditioning reduces infarct size of the in vivo rat heart: role of PI3-K, mTOR, GSK-3β, and apoptosis

Post-conditioning by repetitive cycles of reperfusion/ischemia after prolonged ischemia protects the heart from infarction. The objectives of this study were: Are kinases (PI3-kinase, mTOR, and GSK-3β) involved in the signaling pathway of post-conditioning? Does post-conditioning result in a diminished necrosis or apoptosis? In open chest rats the infarct size was determined after 30 min of regional ischemia and 30 min of reperfusion using propidium iodide and microspheres. Post-conditioning was performed by three cycles of 30 s reperfusion and reocclusion each, immediately upon reperfusion. PI3-kinase and mTOR were blocked using wortmannin (0.6 mg/kg) or rapamycin (0.25 mg/kg), respectively. The phosphorylation of GSK-3β and p70S6K was determined with phospho-specific antibodies. TUNEL staining and detection of apoptosis-inducing factor (AIF) were used for the determination of apoptosis. Control hearts had an infarct size of 49 ± 3%, while post-conditioning significantly reduced it to 29 ± 3% (P < 0.01). Wortmannin as well as rapamycin completely blocked the infarct size reduction of post-conditioning (51 ± 2% and 54 ± 5%, respectively). Western blot analysis revealed that post-conditioning increased the phosphorylation of GSK-3β by 2.3 times (P < 0.01), and this increase could be blocked by wortmannin, a PI3-kinase inhibitor. Although rapamycin blocked the infarct size reduction, phosphorylation of p70S6K was not increased in post-conditioned hearts. After 2 h of reperfusion, the post-conditioned hearts had significantly fewer TUNEL-positive nuclei (35 %) compared to control hearts (53%; P < 0.001). AIF was equally reduced in post-conditioned rat hearts (P < 0.05 vs. control). Infarct size reduction by ischemic post-conditioning of the in vivo rat heart is PI3-kinase dependent and involves mTOR. Furthermore, GSK-3β, which is thought to be a regulator of the mPTP, is part of the signaling pathway of post-conditioning. Finally, apoptosis was inhibited by post-conditioning, which was shown by two independent methods. The role of apoptosis and/or autophagy in post-conditioning has to be further elucidated to find therapeutic targets to protect the heart from the consequences of acute myocardial infarction.     

Purification of a peptide from seahorse,that inhibits TPA-induced MMP,iNOS and COX-2 expression through MAPK and NF-κB activation,and induces human osteoblastic and chondrocytic differentiation

Ongoing efforts to search for naturally occurring, bioactive substances for the amelioration of arthritis have led to the discovery of natural products with substantial bioactive properties. The seahorse (Hippocampus kuda Bleeler), a telelost fish, is one source of known beneficial products, yet has not been utilized for arthritis research. In the present work, we have purified and characterized a bioactive peptide from seahorse hydrolysis. Among the hydrolysates tested, pronase E-derived hydrolysate exhibited the highest alkaline phosphatase (ALP) activity, a phenotype marker of osteoblast and chondrocyte differentiation. After its separation from the hydrolysate by several purification steps, the peptide responsible for the ALP activity was isolated and its sequence was identified as LEDPFDKDDWDNWK (1821 Da). We have shown that the isolated peptide induces differentiation of osteoblastic MG-63 and chondrocytic SW-1353 cells by measuring ALP activity, mineralization and collagen synthesis. Our results indicate that the peptide acts during early to late stages of differentiation in MG-63 and SW-1353 cells. We also assessed the concentration dependence of the peptide's inhibition of MMP (-1, -3 and -13), iNOS and COX-2 expression after treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), a common form of phorbol ester. The peptide also inhibited NO production in MG-63 and SW-1353 cells. To elucidate the mechanisms by which the peptide acted, we examined its effects on TPA-induced MAPKs/NF-κB activation and determined that the peptide treatment significantly reduced p38 kinase/NF-κB in MG-63 cells and MAPKs/NF-κB in SW-1353 cells.     

Effects of miR-202-5p silencing PIK3CA gene expression on proliferation,invasion, and epithelial–mesenchymal transition of cervical cancer SiHa cells through inhibiting PI3K/Akt/mTOR signaling pathway activation

Molecular and Cellular Biochemistry - To explore the mechanism of miR-202-5p targeting the expression of PIK3CA and mediating the activation of PI3K/Akt/mTOR signaling pathway on the proliferation,...     

Propofol-induced miR-219-5p inhibits growth and invasion of hepatocellular carcinoma through suppression of GPC3-mediated Wnt/β-catenin signalling activation

Propofol is one of the most extensively used intravenous anaesthetic agents, which has been found to improve the surgical intervention outcome of several types of cancer, including hepatocellular carcinoma (HCC). Additionally, in vitro and in vivo experiments have also indicated that propofol affects the biological behaviour of HCC. However, the underlying mechanisms of the surgical resection of HCC with propofol have not been fully understood. In the present study, we aimed to investigate the underlying mechanism of propofol inhibition of the growth and invasion of HCC cells. Our results showed that treatment with propofol suppressed the proliferation, invasion and migration of HCC in vitro. The subcutaneous xenograft tumour and orthotopic xenograft tumour experiments in nude mice showed that propofol significantly decreased tumour volumes, growth rates and the liver orthotopic xenograft tumour in vivo. Furthermore, the underlying mechanism investigations of the suppressive effects of propofol on HCC cells revealed that propofol treatment upregulated the expression levels of the candidate tumour suppressor miR-219-5p. Silencing of propofol-induced miR-219-5p using anti-miR-219-5p abrogated the inhibitory effects on the proliferation, migration and invasion of HCC cells exerted by propofol treatment. Additionally, we demonstrated that propofol reversed the epithelial-mesenchymal transition of Huh7 and SMMC7721 cells via miR-219-5p induction. The molecular mechanism behind these findings is that propofol-induced miR-219-5p inhibits HCC cell progression by targeting glypican-3 and subsequently results in the inhibition of Wnt/β-catenin signalling. Taken together, our study provides new insights into the advantages of the surgical intervention of HCC with propofol anaesthetization.     

The UII/UT System Mediates Upregulation of Proinflammatory Cytokines through p38 MAPK and NF-κB Pathways in LPS-Stimulated Kupffer Cells

The urotensin II (UII)/UII receptor (UT) system is closely related to immune inflammation. In acute liver failure (ALF), the UII/UT system can promote the production and release of proinflammatory cytokines, inducing an inflammatory injury response in liver tissue. However, the mechanism by which the hepatic UII/UT system promotes proinflammatory cytokine production and release is not clear. To solve this problem, we used primary Kupffer cells (KCs) as the model system in the current study. The results showed that after lipopolysaccharide (LPS) stimulation, KCs showed significantly increased expression and release of UII/UT and proinflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Pretreatment with urantide, which is a UT receptor antagonist, significantly inhibited the LPS-stimulated expression and release of UII/UT, TNF-α, and IL-1β by KCs. In addition, LPS stimulation induced nuclear p38 mitogen-activated protein kinase (MAPK) protein phosphorylation and expression of the nuclear nuclear factor κB (NF-κB) p65 subunit in KCs and enhanced the binding activity of NF-κB to DNA molecules, whereas urantide pretreatment significantly inhibited the LPS-stimulated nuclear expression and activity of these molecules in KCs. Therefore, our conclusion is that the UII/UT system mediates LPS-stimulated production and release of proinflammatory cytokine by KCs, and this mediating effect at least partially relies on the inflammatory signaling pathway molecules p38 MAPK and NF-κB.