Toll-like receptors (TLRs) are the archetypal pattern recognition receptors in sensing exogenous pathogens. Activation of TLRs is a first line of defense of the immune system, leading to the activation and recruitment of neutrophils and macrophages to sites of infection and enhances antimicrobial activity. The TLR signaling through different intracellular molecules, such as MAP kinases and IkappaB kinases which are conserved signaling elements for many receptors, leads to a distinct set of proinflammatory gene expressions. However, how these pathways differentially and precisely control the transcription of identical genes remains largely unknown. Our review focuses on the details of up-to- date signaling molecules including negative regulators and their role in controlling innate immune response. We also stress the importance of developing systemic approaches for the global understanding of TLR signaling so that appropriate drug therapeutic targets can be identified for regulating inflammatory diseases.
Adaptor Proteins, Signal Transducing/*immunology ; Animals ; Humans ; MAP Kinase Signaling System/*immunology ; Receptor Cross-Talk ; Receptors, Interleukin-1/immunology ; *Signal Transduction ; Toll-Like Receptors/*immunology

A primitive protozoan parasite Trichomonas vaginalis selectively activates the signal transduction pathways in macrophages (RAW264.7). This study evaluated the correlation of these signaling pathways and T. vaginalis-induced cell apoptosis. In macrophages infected with T. vaginalis, apoptosis was assessed on the basis of DNA fragmentation on agarose gel electrophoresis. Infection of macrophages with T. vaginalis induced tyrosine phosphorylation of several proteins. Infected cells with T. vaginalis were shown to associate with phosphorylation of the extracellular signal-regulated (ERK) 1/2 kinase, p38, c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinases on Western blot analysis. The present finding also demonstrated a link between the ERK1/2, JNK and p38 apoptotic pathways that was modulated by T. vaginalis infection.
Animals ; Apoptosis/*immunology ; Humans ; MAP Kinase Signaling System/immunology ; Macrophages/*cytology/enzymology/*parasitology ; Mitogen-Activated Protein Kinases/*metabolism ; Phosphorylation ; Trichomonas Infections/*immunology ; Trichomonas vaginalis/*immunology

To investigate the effects of DENV infection on the expression of Vascular endothelial growth factor (VEGF) in monocytes, and to explore which innate immune signaling pathway is responsible for VEGF induction. Real-time PCR was used to determine the expression levels of VEGF in DENV-infected THP-1. We found that different serotype viruses (DENV1, DENV2, DENV3) induced the VEGF expression. Moreover, VEGF expression was significantly increased in human primary monocytes infected with DENV 2. In addition, VEGF induction by DENV2 was significantly impaired by knockdown of TLR3 and interferon-beta promoter stimulator 1 (IPS-1), or by inhibition of ERK, JNK or NF-kappaB. These results demonstrated that DENV induced VEGF expression in monocytes, and the activation of TLR3, IPS-1 signal pathways were required for DENV2-triggered VEGF induction, suggesting that VEGF might be a promising therapeutic target for DHF.
Dengue ; genetics ; immunology ; virology ; Dengue Virus ; classification ; genetics ; physiology ; Humans ; MAP Kinase Signaling System ; Monocytes ; NF-kappa B ; genetics ; immunology ; Up-Regulation ; Vascular Endothelial Growth Factor A ; genetics ; immunology

The p38 mitogen-activated protein kinase (MAPK) plays an evolutionarily conserved role in the cellular response to microbial infection and environmental stress. Activation of p38 is mediated through phosphorylation by upstream MAPKK, which in turn is activated by MAPKKK. In the Caenorhabditis elegans, the p38 MAPK (also called PMK-1) signaling pathway has been shown to be required in its resistance to bacterial infection. However, how different upstream MAP2Ks and MAP3Ks specifically contribute to the activation of PMK-1 in response to bacterial infection still is not clearly understood. By using double-stranded RNA-mediated interference (RNAi) and genetic mutants of C. elegans, we demonstrate that C. elegans MOM-4, a mammalian TAK1 homolog, is required for the resistance of C. elegans to a P. aeruginosa infection. We have also found that the MKK-4 of C. elegans is required for P. aeruginosa resistance, but not through the regulation of DLK-1. In summary, our results indicate that different upstream MAPKKKs or MAPKKs regulate the activation of PMK-1 in response to P. Aeruginosa.
Animals ; Caenorhabditis elegans ; enzymology ; genetics ; immunology ; microbiology ; Caenorhabditis elegans Proteins ; genetics ; metabolism ; Disease Resistance ; Enzyme Activation ; MAP Kinase Kinase 1 ; metabolism ; MAP Kinase Signaling System ; Membrane Proteins ; deficiency ; genetics ; metabolism ; Mutation ; Pseudomonas Infections ; enzymology ; Pseudomonas aeruginosa ; physiology ; RNA Interference ; p38 Mitogen-Activated Protein Kinases ; metabolism

Cyclooxygenase-2 (COX-2) is an important enzyme in inflammation. In this study, we investigated the underlying molecular mechanism of the synergistic effect of rottlerin on interleukin1beta (IL-1beta)-induced COX-2 expression in MDA-MB-231 human breast cancer cell line. Treatment with rottlerin enhanced IL-1beta-induced COX-2 expression at both the protein and mRNA levels. Combined treatment with rottlerin and IL-1beta significantly induced COX-2 expression, at least in part, through the enhancement of COX-2 mRNA stability. In addition, rottlerin and IL-1beta treatment drove sustained activation of p38 Mitogen-activated protein kinase (MAPK), which is involved in induced COX-2 expression. Also, a pharmacological inhibitor of p38 MAPK (SB 203580) and transient transfection with inactive p38 MAPK inhibited rottlerin and IL-1beta-induced COX-2 upregulation. However, suppression of protein kinase C delta (PKC delta) expression by siRNA or overexpression of dominant-negative PKC delta (DN-PKC-delta) did not abrogate the rottlerin plus IL-1beta-induced COX-2 expression. Furthermore, rottlerin also enhanced tumor necrosis factor-alpha (TNF-alpha), phorbol myristate acetate (PMA), and lipopolysaccharide (LPS)-induced COX-2 expression. Taken together, our results suggest that rottlerin causes IL-1beta-induced COX-2 upregulation through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells.
Acetophenones/*pharmacology ; Benzopyrans/*pharmacology ; Breast Neoplasms/drug therapy/*genetics/immunology ; Cell Line, Tumor ; Cyclooxygenase 2/*genetics ; Enzyme Activation/drug effects ; Enzyme Inhibitors/*pharmacology ; Female ; Gene Expression Regulation, Neoplastic/*drug effects ; Humans ; Interleukin-1beta/*immunology ; MAP Kinase Signaling System/drug effects ; Mallotus Plant/chemistry ; NF-kappa B/immunology ; Protein Kinase C-delta/antagonists & inhibitors ; Reactive Oxygen Species/immunology ; p38 Mitogen-Activated Protein Kinases/*immunology

Dendritic cells (DCs), which are regarded as the most potent antigen-presenting cells, are involved in innate and adaptive immunity. Upon uptake of pathogens, DCs express cell surface markers and secrete cytokines. In this study, we analyzed production of cytokines and found that interleukin (IL)-10 and transforming growth factor (TGF)-beta production significantly increased in bone marrow-derived DCs and a mouse DC line, DC2.4, after treatment with crude antigen (CA) from liver fluke, Clonorchis sinensis. However, expression patterns of several activation molecules did not change. In addition, following treatment of DC2.4 cells with antigen from the lung fluke, Paragonimus westermani, production of IL-10 and TGF-beta significantly increased compared with groups treated with other parasite antigens, Spirometra erinacei plerocercoid CA and Echinococcus granulosus hydatid cystic fluid. We also found that treatment of DC2.4 cells with C. sinensis CA resulted in rapid and significant phosphorylation of extracellular signal-regulated kinase 1/2, a mitogen-activated protein kinase. Following treatment of DC2.4 cells with C. sinensis CA, treatment with an inhibitor specific to an extracellular signal-regulated kinase inhibited production of IL-10 and TGF-beta. Our results suggest that CA from C. sinensis has a role in the anti-inflammatory function of DC cells by inducing IL-10 and TGF-beta through activation of extracellular signal-regulated kinase 1/2.
Animals ; Antigens, Helminth/*pharmacology ; Cells, Cultured ; Clonorchis sinensis/*immunology ; Dendritic Cells/drug effects/*metabolism ; Interleukin-10/genetics/*metabolism ; MAP Kinase Signaling System ; Mice ; Transforming Growth Factor beta/genetics/*metabolism

BACKGROUND: Epidemiological studies have suggested that noise exposure may increase the risk of type 2 diabetes mellitus (T2DM), and experimental studies have demonstrated that noise exposure can induce insulin resistance in rodents. The aim of the present study was to explore noise-induced processes underlying impaired insulin sensitivity in mice. METHODS: Male ICR mice were randomly divided into four groups: a control group without noise exposure and three noise groups exposed to white noise at a 95-dB sound pressure level for 4 h/day for 1, 10, or 20 days (N1D, N10D, and N20D, respectively). Systemic insulin sensitivity was evaluated at 1 day, 1 week, and 1 month post-noise exposure (1DPN, 1WPN, and 1MPN) via insulin tolerance tests (ITTs). Several insulin-related processes, including the phosphorylation of Akt, IRS1, and JNK in the animals' skeletal muscles, were examined using standard immunoblots. Biomarkers of inflammation (circulating levels of TNF-α and IL-6) and oxidative stress (SOD and CAT activities and MDA levels in skeletal muscles) were measured via chemical analyses. RESULTS: The data obtained in this study showed the following: (1) The impairment of systemic insulin sensitivity was transient in the N1D group but prolonged in the N10D and N20D groups. (2) Noise exposure led to enhanced JNK phosphorylation and IRS1 serine phosphorylation as well as reduced Akt phosphorylation in skeletal muscles in response to exogenous insulin stimulation. (3) Plasma levels of TNF-α and IL-6, CAT activity, and MDA concentrations in skeletal muscles were elevated after 20 days of noise exposure. CONCLUSIONS Impaired insulin sensitivity in noise-exposed mice might be mediated by an enhancement of the JNK/IRS1 pathway. Inflammation and oxidative stress might contribute to insulin resistance after chronic noise exposure.
Animals ; Biomarkers ; metabolism ; Inflammation ; physiopathology ; Insulin Receptor Substrate Proteins ; genetics ; metabolism ; Insulin Resistance ; genetics ; immunology ; MAP Kinase Signaling System ; physiology ; Male ; Mice ; Mice, Inbred ICR ; Mitogen-Activated Protein Kinase 8 ; genetics ; metabolism ; Noise ; adverse effects ; Oxidative Stress ; physiology ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; Random Allocation ; Time Factors

OBJECTIVETo observe the effect of andrographolide on the activation of mitogen-activated protein kinases (MAPKs) and expression of nuclear factor-κB (NF-κB) in macrophage foam cells.

METHODSThe mouse peritoneal macrophages were cultured in the media in the presence of oxidized low-density lipoprotein (ox-LDL), ox-LDL+andrographolide, or neither (control). The phosphorylation of MAPK molecules (p38MAPK, JNK, ERK1/2) and the expressions of NK-κB p65 were examined by Western blot.

RESULTSAs compared with cells in the control group, the expressions of phospho-p38 and NF-κB p65 were increased in the cells cultured with either ox-LDL or ox-LDL+andrographolide (P<0.01), but attenuated significantly in the presence of ox-LDL+ andrographolide when compared with ox-LDL (P<0.05). The phospho-JNK increased in the presence of either ox-LDL or ox-LDL+andrographolide when compared with control cells (P<0.01), but no significant difference existed between ox-LDL and ox-LDL+andrographolide (P>0.05). The expression of phospho-ERK1/2 was increased in the presence of ox-LDL compared with the control cells (P<0.01), but no significant differences existed between the cells cultured in the presence of ox-LDL+andrographolide and the control medium (P>0.05).

CONCLUSIONSAndrographolide could inhibit the activation of ERK1/2, p38MAPK and NK-κB induced by ox-LDL in macrophage foam cells, which might be one of its mechanisms in preventing atherosclerosis.

Animals ; Anti-Inflammatory Agents ; pharmacology ; Atherosclerosis ; immunology ; metabolism ; prevention & control ; Cells, Cultured ; Diterpenes ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Foam Cells ; cytology ; drug effects ; enzymology ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Lipoproteins, LDL ; metabolism ; MAP Kinase Signaling System ; drug effects ; immunology ; Macrophages, Peritoneal ; cytology ; drug effects ; enzymology ; Mice ; Mice, Inbred Strains ; NF-kappa B ; metabolism ; Vasculitis ; drug therapy ; immunology ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism