Induced Production (induced + production)

Distribution by Scientific Domains

Selected Abstracts

An ecological cost of plant defence: attractiveness of bitter cucumber plants to natural enemies of herbivores

Anurag A. Agrawal
Abstract Plants produce defences that act directly on herbivores and indirectly via the attraction of natural enemies of herbivores. We examined the pleiotropic effects of direct chemical defence production on indirect defence employing near-isogenic varieties of cucumber plants (Cucumis sativus) that differ qualitatively in the production of terpenoid cucurbitacins, the most bitter compounds known. In release,recapture experiments conducted in greenhouse common gardens, blind predatory mites were attracted to plants infested by herbivorous mites. Infested sweet plants (lacking cucurbitacins), however, attracted 37% more predatory mites than infested bitter plants (that produce constitutive and inducible cucurbitacins). Analysis of the headspace of plants revealed that production of cucurbitacins was genetically correlated with large increases in the qualitative and quantitative spectrum of volatile compounds produced by plants, including induced production of (E,)-,-ocimene (3E,)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-,-farnesene, and methyl salicylate, all known to be attractants of predators. Nevertheless, plants that produced cucurbitacins were less attractive to predatory mites than plants that lacked cucurbitacins and predators were also half as fecund on these bitter plants. Thus, we provide novel evidence for an ecological trade-off between direct and indirect plant defence. This cost of defence is mediated by the effects of cucurbitacins on predator fecundity and potentially by the production of volatile compounds that may be repellent to predators. [source]

A pathway through interferon-, is the main pathway for induction of nitric oxide upon stimulation with bacterial lipopolysaccharide in mouse peritoneal cells

FEBS JOURNAL, Issue 19 2003
Motohiro Matsuura
Production of nitric oxide (NO) in response to bacterial lipopolysaccharide (LPS) was investigated using cultures of mouse peritoneal exudate cells (PEC) and the macrophage cell line RAW264.7. In the presence of anti-(interferon-,) (IFN-,), NO production was markedly suppressed in the PEC culture but not in the RAW264.7 culture. In the PEC culture, LPS induced both IFN-, production and activation of IFN response factor-1, which leads to the gene expression of inducible NO synthase, but neither was induced in the culture of RAW264.7 cells. In addition to anti-(IFN-,), antibodies against interleukin (IL)-12 and IL-18 showed a suppressive effect on LPS-induced NO production in the PEC culture, and these antibodies in synergy showed strong suppression. Stimulation of the PEC culture with IL-12 or IL-18 induced production of IFN-, and NO, and these cytokines, in combination, exhibited marked synergism. Stimulation of the culture with IFN-, induced production of NO, but not IL-12. The macrophage population in the PEC, prepared as adherent cells, responded well to LPS for IL-12 production, but weakly for production of IFN-, and NO. The macrophages also responded well to IFN-, for NO production. For production of IFN-, by stimulation with LPS or IL-12 + IL-18, nonadherent cells were required in the PEC culture. Considering these results overall, the indirect pathway, through the production of intermediates (such as IFN-,-inducing cytokines and IFN-,) by the cooperation of macrophages with nonadherent cells, was revealed to play the main role in the LPS-induced NO production pathway, as opposed to the direct pathway requiring only a macrophage population. [source]

Sulphasalazine inhibits macrophage activation: inhibitory effects on inducible nitric oxide synthase expression, interleukin-12 production and major histocompatibility complex II expression

IMMUNOLOGY, Issue 4 2001
György Haskó
Summary The anti-inflammatory agent sulphasalazine is an important component of several treatment regimens in the therapy of ulcerative colitis, Crohn's disease and rheumatoid arthritis. Sulphasalazine has many immunomodulatory actions, including modulation of the function of a variety of cell types, such as lymphocytes, natural killer cells, epithelial cells and mast cells. However, the effect of this agent on macrophage (M,) function has not been characterized in detail. In the present study, we investigated the effect of sulphasalazine and two related compounds , sulphapyridine and 5-aminosalicylic acid , on M, activation induced by bacterial lipopolysaccharide (LPS) and interferon-, (IFN-,). In J774 M, stimulated with LPS (10 µg/ml) and IFN-, (100 U/ml), sulphasalazine (50,500 µm) suppressed nitric oxide (NO) production in a concentration-dependent manner. The expression of the inducible NO synthase (iNOS) was suppressed by sulphasalazine at 500 µm. Sulphasalazine inhibited the LPS/IFN-,-induced production of both interleukin-12 (IL-12) p40 and p70. The suppression of both NO and IL-12 production by sulphasalazine was superior to that by either sulphapyridine or 5-aminosalicylic acid. Although the combination of LPS and IFN-, induced a rapid expression of the active forms of p38 and p42/44 mitogen-activated protein kinases and c-Jun terminal kinase, sulphasalazine failed to interfere with the activation of any of these kinases. Finally, sulphasalazine suppressed the IFN-,-induced expression of major histocompatibility complex class II. These results demonstrate that the M, is an important target of the immunosuppressive effect of sulphasalazine. [source]

Natural killer cell-mediated ablation of metastatic liver tumors by hydrodynamic injection of IFN, gene to mice

Tetsuo Takehara
Abstract Interferon (IFN) , is a pleiotropic cytokine acting as an antiviral substance, cell growth inhibitor and immunomodulator. To evaluate the therapeutic efficacy and mechanisms of IFN, on hepatic metastasis of tumor cells, we hydrodynamically injected naked plasmid DNA encoding IFN,1 (pCMV-IFNa1) into Balb/cA mice having 2 days hepatic metastasis of CT-26 cells. Single injection of pCMV-IFNa1 efficiently enhanced the natural killer (NK) activity of hepatic mononuclear cells, induced production of IFN, in serum and led to complete rejection of tumors in the liver. Mice protected from hepatic metastasis by IFN, therapy displayed a tumor-specific cytotoxic T cell response and were resistant to subcutaneous challenge of CT-26 cells. NK cells were critically required for IFN,-mediated rejection of hepatic metastasis, because their depletion by injecting anti-asialo GM1 antibody completely abolished the antimetastatic effect. To find whether NK cells are directly activated by IFN, and are sufficient for the antimetastatic effect, the responses to IFN, were examined in SCID mice lacking T cells, B cells and NKT cells. IFN, completely rejected hepatic metastasis in SCID mice and efficiently activated SCID mononuclear cells, as evidenced by activation of STAT1 and a variety of genes, such as MHC class I, granzyme B, tumor necrosis factor-related apoptosis-inducing ligand and IFN,, and also enhanced Yac1 lytic ability. Study of IFN, knockout mice revealed that IFN, was not necessary for IFN,-mediated NK cell activation and metastasis protection. In conclusion, IFN, efficiently activates both innate and adaptive immune responses, but NK cells are critically required and sufficient for IFN,-mediated initial rejection of hepatic metastasis of microdisseminated tumors. © 2006 Wiley-Liss, Inc. [source]

Interleukin-1, induces MMP-9 expression via p42/p44 MAPK, p38 MAPK, JNK, and nuclear factor-,B signaling pathways in human tracheal smooth muscle cells

Kao-Chih Liang
Matrix metalloproteinases (MMPs) are responsible for degradation of extracellular matrix and play important roles in cell migration, proliferation, and tissue remodeling related to airway inflammation. Interleukin-1, (IL-1,) has been shown to induce MMP-9 production in many cell types and contribute to airway inflammatory responses. However, the mechanisms underlying MMP-9 expression induced by IL-1, in human tracheal smooth muscle cells (HTSMCs) remain unclear. Here, we investigated the roles of p42/p44 MAPK, p38 MAPK, JNK, and NF-,B pathways for IL-1,-induced MMP-9 production in HTSMCs. IL-1, induced production of MMP-9 protein and mRNA in a time- and concentration-dependent manner determined by zymographic, Western blotting, and RT-PCR analyses, which was attenuated by inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190), JNK (SP600125), and NF-,B (helenalin), and transfection with dominant negative mutants of MEK1/2, p38 and JNK, respectively. IL-1,-stimulated phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK was attenuated by pretreatment with U0126, SB202190, SP600125, or transfection with these dominant negative mutants of MEK, ERK, p38 and JNK, respectively. Furthermore, IL-1,-stimulated translocation of NF-,B into the nucleus and degradation of I,B-, was blocked by helenalin. Finally, the reporter gene assay revealed that MAPKs and NF-,B are required for IL-1,-induced MMP-9 luciferase activity in HTSMCs. MMP-9 promoter activity was enhanced by IL-1, in HTSMCs transfected with MMP-9-Luc, which was inhibited by helenalin, U0126, SB202190, and SP600125. Taken together, the transcription factor NF-,B, p42/p44 MAPK, p38 MAPK, and JNK that are involved in MMP-9 expression in HTSMCs exposed to IL-1, have now been identified. J. Cell. Physiol. 211: 759,770, 2007. © 2007 Wiley-Liss, Inc. [source]

Inhibition of interleukin-1,,induced matrix metalloproteinases 1 and 13 production in human osteoarthritic chondrocytes by prostaglandin D2

Nadia Zayed
Objective To investigate the effects of prostaglandin D2 (PGD2) on interleukin-1, (IL-1,),induced matrix metalloproteinase 1 (MMP-1) and MMP-13 expression in human chondrocytes and the signaling pathways involved in these effects. Methods Chondrocytes were stimulated with IL-1 in the presence or absence of PGD2, and expression of MMP-1 and MMP-13 proteins was evaluated by enzyme-linked immunosorbent assay. Messenger RNA (mRNA) expression and promoter activity were analyzed by real-time reverse transcription,polymerase chain reaction and transient transfections, respectively. The role of the PGD2 receptors D prostanoid receptor 1 (DP1) and chemoattractant receptor,like molecule expressed on Th2 cells (CRTH2) was evaluated using specific agonists and antibody-blocking experiments. The contribution of the cAMP/protein kinase A (PKA) pathway was determined using cAMP-elevating agents and PKA inhibitors. Results PGD2 decreased in a dose-dependent manner IL-1,induced MMP-1 and MMP-13 protein and mRNA expression as well as their promoter activation. DP1 and CRTH2 were expressed and functional in chondrocytes. The effect of PGD2 was mimicked by BW245C, a selective agonist of DP1, but not by 13,14-dihydro-15-keto-PGD2, a selective agonist of CRTH2. Furthermore, treatment with an anti-DP1 antibody reversed the effect of PGD2, indicating that the inhibitory effect of PGD2 is mediated by DP1. The cAMP-elevating agents 8-Br-cAMP and forskolin suppressed IL-1,induced MMP-1 and MMP-13 expression, and the PKA inhibitors KT5720 and H89 reversed the inhibitory effect of PGD2, suggesting that the effect of PGD2 is mediated by the cAMP/PKA pathway. Conclusion PGD2 inhibits IL-1,induced production of MMP-1 and MMP-13 by chondrocytes through the DP1/cAMP/PKA signaling pathway. These data also suggest that modulation of PGD2 levels in the joint may have therapeutic potential in the prevention of cartilage degradation. [source]

The squamous cell carcinoma antigens as relevant biomarkers of atopic dermatitis

K. Mitsuishi
Summary Background Although it is thought that both Th1- and Th2-type inflammations are involved in the pathogenesis of atopic dermatitis (AD), it is controversial which immune response is more involved in regulating the clinical severity of AD. We recently found that the squamous cell carcinoma antigens 1 (SCCA1) and SCCA2 are novel biomarkers of bronchial asthma, downstream of IL-4 and IL-13. Objective We examined whether SCCA1 and SCCA2 could also serve as biomarkers of AD, reflecting its Th2-type immune responses, and whether the expression level of SCCA was correlated with clinical severity of AD. Method We compared the expression of SCCA1 and SCCA2 at the mRNA and protein levels in both involved and uninvolved skin of AD patients and in normal control skin. We next analysed induction of SCCA by IL-4 or IL-13 in keratinocytes. Finally, we compared the serum level of SCCA with laboratory parameters reflecting Th2-type inflammation and clinical severity in AD patients. Results SCCA1 and SCCA2 were highly expressed in involved skin of AD patients, compared with their uninvolved skin, at both mRNA and protein levels. SCCA protein was dominantly expressed in suprabasal keratinocytes in the epidermis of AD patients. Either IL-4 or IL-13, but not IFN-, or TNF, induced production of SCCA in keratinocytes. These result suggest that SCCA is induced in AD skin, probably due to direct actions of IL-4 and/or IL-13 on keratinocytes. Serum levels of SCCA were well correlated with eosinophil numbers and serum lactate dehydrogenase levels, and weakly with serum IgE levels, in AD patients. Furthermore, serum levels of SCCA were strongly correlated with clinical severity. Conclusions Th2-type inflammation dominantly regulates the clinical severity of AD, and SCCA is a relevant biomarker of AD, reflecting both Th2-type inflammation and clinical severity. [source]