Sook-Kyoung Heo

LPS induces inflammatory responses in human aortic vascular smooth muscle cells via Toll-like receptor 4 expression and nitric oxide production

Inflammation is an important event in the development of vascular diseases such as hypertension, atherosclerosis, and restenosis. In addition, the stimulation of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) induces the release of critical proinflammatory cytokines that activate potent immune responses. In this study, LPS was found to induce TLR4 expression and increased nitric oxide (NO) production by increasing the expression of inducible nitric oxide synthase (iNOS). Furthermore, LPS was found to induce interleukin (IL)-8 and vascular endothelial growth factor (VEGF) production, as well as intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression. Taken together, these results indicate that LPS induces inflammatory responses in HASMC. Moreover, NOS inhibitor (L-NAME) and anti-TLR 4mAb reduced the LPS-induced NO, IL-8 and VEGF production and ICAM-1 expression. Additionally, TLR4 expression was reduced by NOS inhibitor. Taken together, these results indicate that LPS-induced inflammatory responses are regulated by TLR4 expression and NO production.

LIGHT enhances the bactericidal activity of human monocytes and neutrophils via HVEM.

Human monocytes and neutrophils play major roles in clearing bacteria from human blood and tissues. We found that the herpes virus entry mediator (HVEM) was highly expressed in monocytes and neutrophils, and its interaction with “homologous to lymphotoxins, shows inducible expression, and competes with herpes simplex virus glycoprotein D for HVEM/tumor necrosis factor (TNF)‐related 2” (LIGHT) enhanced bactericidal activity against Listeria monocytogenes and Staphylococcus aureus. The LIGHT‐HVEM interaction increased levels of phagocytosis, interleukin (IL)‐8, TNF‐α, nitric oxide (NO), and reactive oxygen species (ROS) in monocytes and neutrophils. Anti‐HVEM monoclonal antibody was able to block LIGHT‐induced bactericidal activity, cytokine production (IL‐8 and TNF‐α), and ROS generation. Moreover, inhibition of ROS and NO production blocked LIGHT‐induced bactericidal activity. Our results indicate that the LIGHT/HVEM interaction in monocytes and neutrophils contributes to antibacterial activity.

Immunity to melanoma mediated by 4-1BB is associated with enhanced activity of tumour-infiltrating lymphocytes

4‐1BB costimulates T cells to carry out effector functions such as eradication of established tumours. 4‐1BB (CD137) is a member of the TNF receptor family, and its triggering by either 4‐1BB ligand or antibody ligation induces T‐cell activation and growth. We analysed tumour‐infiltrating lymphocytes (TIL) in the experimental B16F10 melanoma model to determine the mechanisms involved in 4‐1BB‐mediated tumour suppression. 4‐1BB+/+ mice survived longer than 4‐1BB–/– mice, and survival was further prolonged by triggering 4‐1BB with an agonistic mAb. The number of metastatic B16F10 colonies in the lung was much greater in 4‐1BB–/– mice than in their 4‐1BB+/+ littermates. Administration of agonistic anti‐4‐1BB mAb increased the number of TIL in the tumour masses in the lungs of 4‐1BB+/+ mice. The numbers of CD4+ T, CD8+ T and CD11b+ TIL increased in these mice. Anti‐4‐1BB mAb induced not only CD8+ 4‐1BB+ T cells but also a CD8+ IFN‐γ+ T‐cell population. B16F10 cells from the lungs of anti‐4‐1BB‐treated mice showed enhanced expression of MHC class Ι and II antigens compared with the same cells from control IgG‐treated mice. Thus, the increase in number of CD8+ T cells and enhanced MHC Ι and II expression in B16F10 cells that result from augmented IFN‐γ production in response to anti‐4‐1BB mAb may lead to suppression of tumour growth and metastasis.

Emodin and rhein inhibit LIGHT-induced monocytes migration by blocking of ROS production

LIGHT is known to act as a novel mediator for atherogenesis. Furthermore, it has been reported that emodin, an active component extracted from rhubarb, can stop the growth of cancer cells. However, it is not known if emodin exerts anti-atherogenic effects in the human monocyte, THP-1, following treatment with LIGHT. In this study, we evaluated the inhibitory effect of emodin and rhein on LIGHT-induced migration in THP-1. Emodin and rhein decreased the level of LIGHT-induced generation of ROS, as well as the expression of CCR1, CCR2 and ICAM-1 and the production of IL-8, MCP-1, TNF-alpha, and IL-6. Emodin and rhein also decreased the phosphorylation of the p38 MAPK and IkB-alpha. Furthermore, the NADPH oxidase assembly inhibitor, AEBSF, and the blocker of NADPH oxidase, p47(phox) small interference RNA (siRNA), also efficiently blocked LIGHT-induced migration, CCR1, CCR2, ICAM-1, and HVEM expression, and p38 MAPK and NF-kB activation. These findings indicate that the inhibitory effects of emodin and rhein on LIGHT-induced migration occur via decreasing ROS production and NADPH oxidase p47(phox) activation. Taken together, these results indicate that emodin and rhein have the potential for use as an anti-atherosclerosis agent.

Emodin inhibits TNF‐α‐induced human aortic smooth‐muscle cell proliferation via caspase‐ and mitochondrial‐dependent apoptosis

Vascular smooth‐muscle cell (VSMC) proliferation plays a vital role in hypertension, atherosclerosis and restenosis. It has been reported that emodin, an active component extracted from rhubarb, can stop the growth of cancer cells; however, it is not known if emodin exerts similar anti‐atherogenic effects in TNF‐α treated human aortic smooth‐muscle cells (HASMC). In this study, emodin treatment showed potent inhibitory effects in TNF‐α‐induced HASMC proliferation that were associated with induced apoptosis, including the cleavage of poly ADP‐ribose polymerase (PARP). Moreover, inhibitors of caspase‐3, ‐8 and ‐9 (Ac‐DEVD‐CHO, Z‐IETD‐FMK and Z‐LEHD‐FMK) efficiently blocked emodin‐induced apoptosis in TNF‐α treated HASMC. Therefore, emodin‐induced cell death occurred via caspase‐dependent apoptosis. Emodin treatment resulted in the release of cytochrome c into cytosol and a loss of mitochondrial membrane potential (ΔΨm), as well as a decrease in the expression of an anti‐apoptotic protein (Bcl‐2) and an increase in the expression of an a pro‐apoptotic protein (Bax). Emodin‐mediated apoptosis was also blocked by a mitochondrial membrane depolarization inhibitor, which indicates that emodin‐induced apoptosis occurred via a mitochondrial pathway. Taken together, the results of this study showed that emodin inhibits TNF‐α‐induced HASMC proliferation via caspase‐ and a mitochondrial‐dependent apoptotic pathway. In addition, these results indicate that emodin has potential as an anti‐atherosclerosis agent. J. Cell. Biochem. 105: 70–80, 2008.

Evodiamine and rutaecarpine inhibit migration by LIGHT via suppression of NADPH oxidase activation.

LIGHT acted as a new player in the atherogenesis. The dried, unripe fruit of Evodia Fructus (EF) has long been used as a traditional Chinese herbal medicine, and is currently widely used for the treatment of headache, abdominal pain, vomiting, colds and reduced blood circulation. Evodiamine and rutaecarpine are active components of EF. In this study, we investigated the inhibitory effect of evodiamine and rutaecarpine on LIGHT‐induced migration in human monocytes. Evodiamine and rutaecarpine decreased the LIGHT‐induced production of ROS, IL‐8, monocyte chemoattractant protein‐1 (MCP‐1), TNF‐α, and IL‐6, as well as the expression of chemokine receptor (CCR) 1, CCR2 and ICAM‐1 and the phosphorylation of the ERK 1/2 and p38 MAPK. Furthermore, NADPH oxidase assembly inhibitor, AEBSF, blocked LIGHT‐induced migration and activation of CCR1, CCR2, ICAM‐1, and MAPK such as ERK and p38 in a manner similar to evodiamine and rutaecarpine. These findings indicate that the inhibitory effects of evodiamine and rutaecarpine on LIGHT‐induced migration and the activation of CCR1, CCR2, ICAM‐1, ERK, and p38 MAPK occurs via decreased ROS production and NADPH oxidase activation. Taken together, these results indicate that evodiamine and rutaecarpine have the potential for use as an anti‐atherosclerosis agent. J. Cell. Biochem. 107: 123–133, 2009.

Stimulation of the Molecule 4-1BB Enhances Host Defense against Listeria monocytogenes Infection in Mice by Inducing Rapid Infiltration and Activation of Neutrophils and Monocytes

ABSTRACT The tumor necrosis factor receptor family molecule 4-1BB (CD137) has diverse roles in adaptive and innate immune responses. However, little is known of its role in bacterial infections. Previously, we showed that 4-1BB-deficient mice have enhanced susceptibility to Listeria monocytogenes infection, and mice pretreated with agonistic anti-4-1BB antibody (3E1) were much more resistant to L. monocytogenes infection than mice treated with control antibody. In this study, we report that stimulating 4-1BB by administering 3E1 in the early phase of L. monocytogenes infection is critical for promoting the survival of mice by inducing rapid infiltration of neutrophils and monocytes into L. monocytogenes-infected livers. The levels of tumor necrosis factor alpha, interleukin 6, and monocyte chemoattractant protein 1 in the livers of 3E1-treated mice increased as early as 30 min postinfection and peaked by 1 to 2 h, while those in mice treated with control antibody started to increase only at 16 h postinfection. Monocytes and neutrophils from the 3E1-treated mice had higher levels of activation markers, phagocytic activity, and reactive oxygen species than those from control mice. In vitro stimulation of 4-1BB induced the production of the inflammatory cytokines/chemokines of neutrophils, but not those of monocytes. These results suggest that 4-1BB stimulation of neutrophils in the early phase of L. monocytogenes infection causes rapid production of inflammatory cytokines/chemokines and that the subsequent infiltration of neutrophils and monocytes is crucial for eliminating the infecting L. monocytogenes.

Ethylacetate extract from Draconis Resina inhibits LPS-induced inflammatory responses in vascular smooth muscle cells and macrophages via suppression of ROS production.

Draconis Resina (DR) is a type of dragons blood resin obtained from Daemomorops draco BL. (Palmae). DR has long been used as a traditional Korean herbal medicine, and is currently used in traditional clinics to treat wounds, tumors, diarrhea, and rheumatism, insect bites and other conditions. In this study, we evaluated fractionated extracts of DR to determine if they inhibited the production of interleukin-1beta (IL-1beta) and the expression of cyclooxygenase (COX)-2. The results of this analysis revealed that the ethylacetate extract of Draconis Resina (DREA) was more potent than that of other extracts. Moreover, DREA inhibited the production of nitric oxide (NO), reactive oxygen species (ROS), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), IL-8 and IL-6 in lipopolysaccharide (LPS)-treated human aortic smooth muscle cells (HASMC) and RAW 264.7 macrophages. Furthermore, treatment with an NADPH oxidase assembly inhibitor, AEBSF, efficiently blocked LPS-induced mitogen-activated protein kinases (MAPKs) activation, as did DREA. These findings indicate that DREA inhibits the production of NO, PGE(2), TNF-alpha, IL-8, and IL-6 by LPS via the inhibition of ROS production, which demonstrates that DREA inhibits LPS-induced inflammatory responses via the suppression of ROS production. Taken together, these results indicate that DREA has the potential for use as an anti-atherosclerosis agent.

Rhein Inhibits TNF-α-Induced Human Aortic Smooth Muscle Cell Proliferation via Mitochondrial-Dependent Apoptosis

Background: Vascular smooth-muscle cell proliferation plays an important role in atherosclerosis and restenosis. Rhein is an active component extracted from rhubarb. In this study, rhein was found to exert potent inhibitory effects against tumor necrosis factor (TNF)-α-induced human aortic smooth-muscle cells (HASMCs) proliferation. Method: These effects were associated with induced apoptosis, including the induction of Annexin V-positive cells, the cleavage of poly(ADP-ribose)polymerase (PARP), and caspases 3, 8 and 9. Results: Inhibitors of caspases 3, 8 and 9 were efficiently blocked by rhein-induced apoptosis in TNF-α-treated HASMCs. In addition, treatment with rhein resulted in the release of cytochrome c into the cytosol, a loss of mitochondrial membrane potential (ΔΨm), a decrease in Bcl-2 and Bcl-xL and an increase in Bax and Bak expression. However, rhein-mediated apoptosis was blocked by a mitochondrial membrane depolarization inhibitor. These findings indicate that rhein-induced apoptosis occurred via a mitochondrial pathway. Furthermore, the inhibition of mitochondrial membrane depolarization was efficiently blocked by rhein-induced caspase-9 activity, which indicates that the rhein-induced caspase activation signal was downstream of the mitochondrial pathway. Taken together, the results of this study show that rhein inhibits TNF-α-induced HASMC proliferation via mitochondria-dependent apoptosis and that rhein has the potential to act as an anti-atherosclerosis agent.

HVEM signaling in monocytes is mediated by intracellular calcium mobilization

Herpes virus entry mediator (HVEM) is a member of the TNF receptor (TNFR) superfamily and is expressed on many immune cells, including T and B cells, NK cells, monocytes, and neutrophils. Interaction of HVEM with its ligand, LIGHT, costimulates T cells and increases the bactericidal activity of monocytes and neutrophils. The interaction recruits cytoplasmic TNFR-associated factor adaptor proteins to the intracellular domain of HVEM. This leads to NFκB activation as a result of IκBα degradation and/or JNK/AP-1 activation, and ultimately results in the expression of genes required for cell survival, cytokine production, or cell proliferation. In this study, we show that treatment of human monocytes with recombinant human LIGHT (rhLIGHT) induces rapid elevation of intracellular calcium concentration ([Ca2+]i) in a HVEM-specific manner in parallel with TNF-α production, and enhances the bactericidal activities of monocytes. Immunoprecipitation and Western blotting analyses revealed phosphorylation of phospholipase Cγ1 (PLCγ1) but not PLCγ2. rhLIGHT-induced Ca2+response was completely abolished by silencing PLCγ1, or preincubating monocytes with PLC inhibitors, antagonists of the inositol-1,4,5-triphosphate receptor, or [Ca2+]i chelators. Furthermore, these PLC/Ca2+ inhibitors also blocked rhLIGHT-mediated IκBα degradation, generation of reactive oxygen species, TNF-α production and the bactericidal activities of monocytes. Our results indicate that Ca2+is a downstream mediator of the LIGHT/HVEM interaction in monocytes.