IL-18 initiates release of matrix metalloproteinase-9 from peripheral blood mononuclear cells without affecting tissue inhibitor of matrix metalloproteinases-1: suppression by TNFα blockage and modulation by IL-10

The proinflammatory cytokine interleukin (IL)-18 appears to be involved in the etiology of a variety of pathological conditions, among them rheumatoid arthritis and atherosclerosis as well as tumor growth and metastasis. As biological activity of matrix metalloproteinase-9 (MMP-9) has been identified as a hallmark in the pathogenesis of these diseases, effects of IL-18 on MMP-9 production by human peripheral blood mononuclear cells (PBMC) were investigated. Moreover, effects of immunopharmacological intervention by anti-tumor necrosis factor-alpha (TNFalpha) or IL-10 were evaluated. Here we report that IL-18 augmented production of MMP-9 by PBMC. The potency of IL-18 to induce release of MMP-9 from PBMC was comparable with that of TNFalpha. MMP-9 production was dependent on endogenous production of TNFalpha, as detected by use of neutralizing monoclonal antibodies. Whereas IL-18 and TNFalpha induced the protease, MMP-9 release was not mediated by IFNgamma. IL-18 also induced secretion of MMP-9 from human whole blood cultures. Antiinflammatory IL-10 efficiently downregulated release of MMP-9 from unstimulated and IL-18-activated PBMC. In contrast to MMP-9, secretion of tissue inhibitor of metalloproteinases-1 (TIMP-1) was not augmented by IL-18. Addition of IL-10 enhanced release of TIMP-1 from PBMC. The present study broadens the current pattern of IL-18 proinflammatory actions on PBMC, emphasizes the pivotal role of intermediate TNFalpha production in these responses, and relates IL-18 biological functions to the pathological role of MMP-9.     

Fumonisin B1-induced localized activation of cytokine network in mouse liver.

Fumonisin B1 (FB1), a mycotoxin produced primarily by Fusarium veticillioides and related fungi, is a carcinogen and causative agent of various animal diseases. Our previous studies indicated the involvement of tumor necrosis factor-alpha (TNFalpha) in FB1-induced hepatotoxicity. Male B6,129 mice (five/group) were injected subcutaneously with vehicle or 2.25 mg/kg/day of FB1 for 5 days and sampled 1 day after the last treatment. FB1 treatment caused an increased expression of TNFalpha, interferon gamma (IFNgamma) and interleukin (IL)-12 p40 in liver without any changes in kidney or spleen, suggesting the localized site of their production. IL-1beta cytokine expression was increased in liver and kidney after FB1 exposure. Cells involved in TNFalpha production after FB1 treatment in liver were identified as Kupffer cells. FB1 increased alanine aminotransferase in plasma and increased apoptotic cells in liver. Selective increase in proinflammatory T helper (Th)1-cytokines (IL-12 and IFNgamma) and TNFalpha with no alteration in Th2-cytokines (IL-4, IL-6 and IL-10) suggest the involvement of IL-12, produced by Kupffer cells, in induction of IFNgamma production by natural killer (NK) cells and/or NK1+ T cells, which can undergo a positive amplification loop with TNFalpha produced by macrophages or other hepatic cells to elicit the toxic reaction.     

Gender-related differences in subacute fumonisin B1 hepatotoxicity in BALB/c mice

Fumonisin B1 (FB1), a potent mycotoxin prevalent in corn, is a carcinogen and causative agent of various animal diseases. Species and sex variations to chronic FB1 toxicity have been reported. Free sphingoid bases and cytokine levels are the two major biochemical alterations of FB1 in vivo and may explain any sex differences in FB1 toxicity. Male and female BALB/c mice (5/group) were injected subcutaneously with either saline vehicle or 2.25 mg/kg/day of FB1 for 5 days. One day after the last injection females showed a greater increase in circulating alanine aminotransferase and greater number of apoptotic cells in liver after FB1 treatment than males, indicating greater hepatotoxicity. Peripheral leukocytic counts, including neutrophils, were increased in females only after FB1 treatment. The increased toxicity in females correlated with a greater increase of sphinganine and sphingosine levels in liver after FB1 treatment compared to males. No sex differences in kidney sphinganine or sphingosine levels were observed after FB1 treatment. Previously we have shown the induction of tumor necrosis factor alpha (TNFalpha) in FB1-induced hepatotoxicity. While in males FB1 treatment caused increased expression of TNFalpha, interleukin (IL)-12 p40, interferon gamma (IFNgamma), IL-1beta, IL-6 and IL-10, females showed an increased expression of IL-6 only, and a downward modulation of IFNgamma, indicating gender differences in cytokine pathways in liver activated by FB1. The basal expression of TNFalpha, IL-12 p40, IL-1beta and IFNgamma in liver of females was higher compared to males. Gender differences in alterations of free sphingoid bases and cytokine modulation after FB1 treatment suggest their possible involvement in sex-dependent differential hepatotoxicity in mice.     

Ex vivo testing of immune responses in precision-cut lung slices

The aim of this study was the establishment of precision-cut lung slices (PCLS) as a suitable ex vivo alternative approach to animal experiments for investigation of immunomodulatory effects. For this purpose we characterized the changes of cytokine production and the expression of cell surface markers after incubation of PCLS with immunoactive substances lipopolysaccharide (LPS), macrophage-activating lipopeptide-2 (MALP-2), interferon gamma (IFNgamma), and dexamethasone. Viability of PCLS from wild-type and CD11c-enhanced yellow fluorescent protein (CD11-EYFP)-transgenic mice was controlled by measurement of lactate dehydrogenase (LDH) enzyme activity and live/dead fluorescence staining using confocal microscopy. Cytokines and chemokines were detected with Luminex technology and ELISA. Antigen presenting cell (APC) markers were investigated in living mouse PCLS in situ using confocal microscopy. LPS triggered profound pro-inflammatory effects in PCLS. Dexamethasone prevented LPS-induced production of cytokines/chemokines such as interleukin (IL)-5, IL-1alpha, TNFalpha, IL-12(p40), and RANTES in PCLS. Surface expression of MHC class II, CD40, and CD11c, but not CD86 was present in APCs of naive PCLS. Incubation with LPS enhanced specifically the expression of MHC class II on diverse cells. MALP-2 only failed to alter cytokine or chemokine levels, but was highly effective in combination with IFNgamma resulting in increased levels of TNFalpha, IL-12(p40), RANTES, and IL-1alpha. PCLS showed characteristic responses to typical pro-inflammatory stimuli and may thus provide a suitable ex vivo technique to predict the immunomodulatory potency of inhaled substances.     

Examination of the immunosuppressive effect of delta9-tetrahydrocannabinol in streptozotocin-induced autoimmune diabetes

delta9-Tetrahydrocannabinol (delta9-THC) is capable of modulating a variety of immune responses, but has not been evaluated in models of immune-based diabetes. The objectives of the present study were: (a) to investigate the effect of delta9-THC in an established model of multiple low dose streptozotocin (MLDSTZ)-induced autoimmune diabetes; and (b) to determine the contribution of the immune response in the MLDSTZ model. CD-1 mice were treated with 40 mg/kg STZ for 5 days in the presence or absence of delta9-THC treatment. delta9-THC administered orally in corn oil at 150 mg/kg for 11 days attenuated, in a transient manner, the MLDSTZ-induced elevation in serum glucose and loss of pancreatic insulin. MLDSTZ-induced insulitis and increases in IFN-gamma, TNFalpha and IL-12 mRNA expression were all reduced on Day 11 by co-administration of delta9-THC. In separate studies, six doses of delta9-THC, given after completion of STZ treatment, was found equally effective in attenuating mice from MLDSTZ-induced diabetes. Studies performed using B6C3F1 mice showed moderate hyperglycemia and a significant reduction in pancreatic insulin by MLDSTZ in the absence of insulitis. In addition, MLDSTZ produced a less pronounced hyperglycemia compared to CD-1 mice that was not attenuated by delta9-THC. These results suggest that MLDSTZ can initiate direct beta-cell damage, thereby augmenting the destruction of beta-cells by the immune system. Moreover, these results indicate that delta9-THC is capable of attenuating the severity of the autoimmune response in this experimental model of autoimmune diabetes.     

Mechanism of TCDD-induced suppression of antibody production: effect on T cell-derived cytokine production in the primary immune reaction of mice.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known to suppress antigen-specific antibody production in humoral immune reactions, but the precise mechanism remains unclear. Since T cell activation and subsequent production of type 2 helper T (Th2) cell-derived cytokines are required for antigen-specific antibody production in humoral immunity, we examined the effects of TCDD on splenic T cell numbers, T cell growth factor IL-2 production, and Th2 cell-derived cytokine production. C57BL/6N mice were orally given TCDD (20 microg/kg) or vehicle, and immediately intraperitoneally immunized with ovalbumin (OVA) adsorbed to alum, and cellular changes in the spleen and cytokine production by spleen cells were investigated from Day 1 to Day 14. In vehicle-control mice the numbers of splenic CD3(+) T cells increased from Day 7 onward, but no increase was observed in the TCDD-exposed mice. When spleen cells from control mice were cultured and restimulated with OVA ex vivo, a significant amount of IL-2 was found from Day 1, but it decreased on Day 7, whereas TCDD exposure promptly suppressed the increase on Day 4. TCDD exposure significantly suppressed the production of Th2 cell-derived cytokines IL-4, IL-5, and IL-6, which were prominently increased from Day 4 onward in control mice. The dose-dependent study showed that IL-5 production was significantly suppressed in a dose-dependent manner starting at 1 microg/kg TCDD. Moreover, separation and reconstitution studies showed that the TCDD-induced suppression of IL-5 production was due to the impaired function of T cells rather than that of antigen-presenting cells. The results of this study suggest that TCDD-induced suppression of T cell activation and Th2-type cytokine production is involved in the impairment of antigen-specific antibody production.     

Synthesis and cytokine modulation properties of pyrrolo[2, 3-d]-4-pyrimidone nucleosides

A series of pyrrolo[2,3-d]pyrimidone nucleosides were synthesized and evaluated for their ability to enhance Type 2 cytokines and to suppress Type 1 cytokines in human T cells activated in vitro. Compounds 16b, 16c, 16d, 18c, and 19b induced substantial enhancement of IL-4 (a Type 2 cytokine) levels while three compounds (16b, 16c, and 16f) showed significant suppression of IFNgamma (a Type 1 cytokine) levels. The results revealed a strict structural requirement for the nucleoside-mediated enhancement of IL-4. Modifications of the ribofuranose moiety of the nucleosides either abolished or dramatically reduced the activity. Both the 5'-hydroxy and 5-carboxamidine are crucial for the activity. Of the few nucleoside analogues that demonstrated enhancement on Type 2 cytokine production, 7-(beta-D-ribofuranosyl)pyrrolo[2, 3-d]-4-pyrimidone-5-carboxamidine (16c) showed a dramatic enhancement (>200%) of IL-4 levels and a significant enhancement (36%) of IL-5 levels. Moreover, this compound showed substantial suppression of the Type 1 cytokines, IFNgamma (42%), IL-2 (54%), and TNFalpha (55%). Similarly, compound 16b showed a substantial enhancement of IL-4 (46%) and suppression of IL-2 (35%), IFNgamma (30%), and TNFalpha (26%). To our knowledge, these are the first nucleoside analogues that induce a Type 2 cytokine bias in T cells. The cytokine modulation property of 16c and 16b merits the therapeutic evaluation of these compounds in treating diseases in which immunopathology is associated with polarized Type 1 cytokine responses.     

Characterization of an interaction between fetal hemoglobin and lipid A of LPS resulting in augmented induction of cytokine production in vivo and in vitro

A previously described extract of sheep fetal liver was reported to reverse many of the cytokine changes associated with aging in mice, including an augmented spleen cell ConA-stimulated production of IL-4 and decreased production of IL-2. Similar effects were not seen with adult liver preparations. These changes were observed in various strains of mice, including BALB/c, DBA/2 and C57BL/6, using mice with ages ranging from 8 to 110 weeks. Preliminary characterization of this crude extract showed evidence for the presence of Hb gamma chain, as well as of lipid A of LPS. We show below that purified preparations of sheep fetal Hb, but not adult Hb, in concert with suboptimally stimulating doses of LPS (lipid A), cooperate in the regulation of production of a number of cytokines, including TNFalpha and IL-6, in vitro. Furthermore, isolated fresh spleen or peritoneal cells from animals treated in vivo with the same combination of Hb and LPS, showed an augmented capacity to produce these cytokines on further culture in vitro. Evidence was also obtained for a further interaction between CLP, LPS and fetal Hb itself in this augmented cytokine production. These data suggest that some of the functional activities in the fetal liver extract reported earlier can be explained in terms of a novel immunomodulatory role of a mixture of LPS (lipid A) and fetal Hb.     

Immuno-regulatory effects of CKBM on the activities of mitogen-activated protein kinases and the release of cytokines in THP-1 monocytic cells

CKBM is an herbal formula composed of five Chinese medicinal herbs (Panax ginseng, Schisandra chinensis, Fructus crataegi, Ziziphus jujube and Glycine Max) supplemented with processed Saccharomyces cerevisiae. Previous studies have demonstrated that CKBM is capable of triggering the release of IL-6 and TNFalpha from human peripheral blood mononuclear cells, and its anti-tumorigenic activity has been demonstrated in nude mice with gastric cancer. In this report, we utilized the THP-1 monocytic cell line as a cellular model to investigate how CKBM regulates the intracellular signaling of monocytes and the subsequent release of the produced cytokines. In terms of mitogen-activated protein kinase (MAPK) cascades, CKBM (20%) had no significant effect on ERK, but was linked to an inhibitory effect on JNK and a stimulatory effect on p38 MAPK. The differential responsiveness of JNK and p38 was dependent on the duration of treatment, as well as on the dosage of CKBM. Treatment of CKBM alone induced the release of IL-10 and IFNgamma, but not IL-1beta, IL-4, IL-6 and TNFbeta, while increase of intracellular Ca2+ concentration by A23187 triggered the release of IL-10 only. Interestingly, A23187 synergized with the activities of CKBM-treated THP-1 cells in terms of IL-1beta and IFNgamma production, while the IL-10 production showed no synergistic relationship between CKBM and A23187. This A23187-induced synergism was associated with a dose-dependent character towards CKBM administration. In view of the intracellular Ca2+ elevation during monocyte activation, our results suggest that CKBM can serve as a promoting agent for modulating the functions of monocytes.     

Patulin influences the expression of Th1/Th2 cytokines by activated peripheral blood mononuclear cells and T cells through depletion of intracellular glutathione

Patulin is a mold toxin secreted mainly by fungi of the Penicillium species. Exposure generally results from consumption of moldy fruits and fruit products. Since recent studies identified mold exposure as a risk factor for allergic diseases, we examined the effects of patulin on human peripheral blood mononuclear cells (PBMC) prepared from buffy coats of healthy donors. Cells were stimulated with CD3- and CD28-specific antibodies in the presence or absence of patulin. Effects of patulin on PBMCs were evaluated by proliferation, viability assays, and cytokine ELISAs. The presence of 50 ng/mL patulin strongly decreased the amounts of several cytokines in the supernatant of stimulated PBMCs. This decrease in cytokine secretion was not due to cytotoxic effects of patulin. Moreover, the extent of the reduction of cytokine amounts was cytokine specific, affecting some (IL-4, IL-13, IFNgamma, and IL-10), but not others (IL-8, IL-5). We show that all effects could be abolished by adding thiol containing compounds. A depletion of intracellular GSH could be measured after incubation of cells with patulin. Taken together, our data indicate that patulin modulates the functional activation of PBMCs with respect to proliferation and cytokine secretion patterns by depletion of intracellular GSH. The depletion of intracellular glutathione may influence the balance between Th1 and Th2 cells and have implications for allergic diseases.     

Effect of Linomide on adhesion molecules, TNF-alpha, nitrogen oxide, and cell adhesion

Linomide (quinoline-3-carboxamide) is an immunomodulator with anti-inflammatory effects in rodents with autoimmune diseases. Its mode of action still remains to be elucidated. We hypothesized that an investigation of T cell interactions with the extracellular matrix (ECM), composed of glycoproteins such as fibronectin (FN) and laminin (LN), might provide better understanding of their in vivo mode of action in extravascular inflammatory sites. We examined the effect of Linomide on T cell adhesion to intact ECM, and separately to LN, and FN, and on the release and production of tumor necrosis factor (TNFalpha) and nitrogen oxide (NO) in relation to adhesive molecules in non-obese diabetic (NOD) female spleen cells, focusing on intracellular adhesion molecule-1 (ICAM-1) and CD44. NOD female mice that developed spontaneous autoimmune insulitis, which destroys pancreatic islets and subsequently leads to insulin-deficient diabetes mellitus, were studied. Linomide, given in the drinking water or added to tissue cultures in vitro, inhibited the beta1 integrin-mediated adhesion of T cells to ECM, FN and LN, as well as the production and release of TNFalpha and NO, which play a major role in the induction and propagation of T cell-mediated insulitis. In addition, exposure of T cells to Linomide resulted in increased expression of CD44 and ICAM-1 molecules on spleen cells of Linomide-treated mice; such an increase in adhesion molecule expression may lead to more effective arrest of T cell migration in vivo. The regulation of T-cell adhesion, adhesion receptor expression, and inhibition of TNFalpha and NO secretion by Linomide may explain its beneficial role and provide a new tool for suppressing self-reactive T cell-dependent autoimmune diseases.     

Activation of murine bone-marrow derived macrophages in vitro with Thymosin-alpha-1 to tumoricidal state: a comparative study on normal and tumour-bearing hosts

The present investigation establishes the ability of Thymosin alpha l (T alpha l) to activate murine bone-marrow derived macrophages (BMDMs) in vitro to tumoricidal state with concomitant release of NO, TNFalpha and IL-1. The T alpha l-induced cytotoxicity and the secretion of soluble lytic factors were both dose- and time dependent. BMDMs cultured from the Dalton's Lymphoma bearing mice (DL-BMDMs) exhibited reduced cytolytic activity towards DL-tumour target cells on activation with T alpha l as compared to the BMDMs obtained from normal mice (N-BMDMs). The DL-BMDMs displayed enhanced TNFalpha and IL-1 release as compared to the N-BMDMs when treated with T alpha l. On the other hand, it is observed that the production of NO and the expression of iNOS was higher in the N-BMDMs as compared to the DL-BMDMs on treatment with T alpha l. Although T alpha l could trigger the tumoricidal functions of BMDMs from normal and DL-tumor bearing hosts, the progressive growth of DL-tumour in ascitic form leads to an alteration in the antitumour response of macrophages. These observations further suggest that a disregulation in the production of inflammatory cytokines like TNF-alpha, IL-1 and the inhibition of NO production in response to DL growth may mutually contribute in explaining the tumour-induced immunosuppression as observed in the DL-bearing mice.     

Enhancement of interleukin 1 and interleukin 2 releases by ubenimex

The effect of ubenimex on the release of interleukin 1 (IL-1) and interleukin 2 (IL-2) from immuno-competent cells was studied. Ubenimex enhanced release of IL-1 from mouse peritoneal macrophages at 1.0 and 100 micrograms/ml in vitro and the release at 1.0 microgram/ml was larger. When ubenimex was administered to mice IL-1-releasing activity of the peritoneal macrophages was enhanced 3 and 5 days after the administration but not enhanced 1 day after the administration. Ubenimex also enhanced IL-2 release from rat spleen cells at 0.1 and 10 micrograms/ml, when concanavalin A (Con A) was added in the IL-2-releasing system. The enhancement was still observed with mouse spleen cells, when serum was further added. Moreover, thymocyte-proliferating activity was attained in the broths which rat spleen cells were incubated with ubenimex from 0.1 to 10 micrograms/ml in the absence and presence of Con A.     

Cytokine expression profiles during murine contact allergy: T helper 2 cytokines are expressed irrespective of the type of contact allergen

We have investigated the cytokine response pattern following sensitisation (induction) of BALB/c mice with different chemicals (dinitrochlorobenzene, dinitrofluorobenzene, oxazolone, glutaraldehyde, formaldehyde, trimellitic anhydride, croton oil) and elicitation (challenge) of contact allergy in sensitised animals. The results of our investigations showed that different chemicals induced both T helper (Th) 1 cytokines [interleukin (IL) 2, interferon beta (IFNgamma) [corrected] and Th2 cytokines (IL-4, IL-10) at different stages during murine contact allergy. We also confirmed our previous findings that IL-4 and IL-10 release were up-regulated during the challenge phase regardless the contact allergen used, whereas the release of IFNgamma [corrected] did not show a clear preference for being up- or down-regulated. In our hands, the increased expression of Th2 cytokines after challenge exposure to contact allergens appeared as a stable marker of secondary contact allergenic responses. Quantitative differences in the expression of IL-4 were observed between different contact allergens. The present results clearly indicate that skin sensitisers were able to elicit cytokine response patterns, which could not be related to a clear-cut Th1 or Th2 type of cytokine response. Furthermore, dermal application of contact allergens produced different kinetics of cytokine secretion upon induction and challenge. In our hands, the co-expression of Th1 and Th2 type cytokines appeared as a universal consequence of dermal application of contact allergens to responsive mice. Our results indicate that co-expression of Th1 and Th2 cytokines during contact allergy is an important feature of murine contact allergy in responsive mice and that chemicals differ in their potency to induce the expression of these cytokines. Furthermore, the results do not support the view that different chemicals induce Th1 or Th2 cytokines in a mutually exclusive manner depending on their preference for inducing either contact or respiratory allergy. The results are expected to renew the discussion about the usefulness of the Th1/Th2 paradigm in certain areas of immunotoxicology.     

Inhibition of in vitro tumor cell proliferation by cytokines induced by combinations of TLR or TLR and TCR agonists

The objective of this study was to learn from in vitro studies how to better utilize Toll-like receptor (TLR) agonists in controlling tumor growth. One of the primary effects of TLR agonists is induction of cytokine and chemokine production. In order to identify combinations of cytokines or chemokines with optimal ability to inhibit in vitro tumor cell proliferation, a panel of 17 recombinant human or mouse cytokines that have minimal effect on primary cell survival, were tested individually or in combinations of 2, 3 or 4 on a panel of human and mouse chemotherapy sensitive and resistant tumor cell lines. A combination of high (>10 ng/ml) levels of IFNgamma with moderate concentrations of TNFalpha>IFNalpha>IL-6=IL-8 was most effective at inhibiting in vitro tumor cell viability and proliferation with minimal effect on primary cells. We also observed that similar cytokine profile could be induced in vitro PBMC culture by using certain combinations of TLR-TLR and TLR-TCR agonists. Thus, concomitant activation of TLR7/8 with TLR4 or TLR 7/8 with T cell receptor (TCR) in PBMC, amongst all possible paired TLR-TLR and TLR-TCR agonist combinations, produced cytokine mix high in IFNgamma, in combination with IFNalpha, IL-6, IL-8, TNFalpha. Such cytokine mix was equal or more effective tumor cell killing and inhibition of tumor cell proliferation than the best rec-cytokine mixture tested. These results suggest that, TLR and/or TCR agonists combinations generate an optimal mixture of cytokines and chemokines competent in regulating in vitro tumor growth, and imply that realizing such "right cytokine induction" in vivo might be more efficacious than that with individual cytokines or TLR agonists induced cytokine mix.     

Regulation of IL-1-induced selective IL-6 release from human mast cells and inhibition by quercetin

Mast cells are involved in allergic reactions, but also in innate immunity and inflammation. Crosslinkage of mast cell Fc immunoglobulin E receptors (FcvarepsilonRI) by multivalent antigen triggers secretion of granule-stored mediators, as well as de novo synthesis of cytokines, including interleukin (IL)-6. We showed recently that the proinflammatory cytokine IL-1 stimulates human leukemic mast cells (HMC-1) and human umbilical cord blood-derived cultured mast cells (hCBMCs) to release newly synthesized IL-6 without tryptase in the absence of degranulation. Here, we investigated several signal-transduction pathways activated by IL-1 leading to IL-6 production by HMC-1 and hCBMCs. We also investigated the effect of the flavonol quercetin that was recently shown to strongly inhibit IL-6 secretion in response to allergic stimulation from hCBMCs.IL-1 stimulated p38, but did not activate extracellular signal-regulated kinase (ERK) or c-jun N-terminal kinase (JNK); it also did not activate protein kinase C (PKC) isozymes alpha, beta, mu and zeta, except for PKC-theta, which was phosphorylated. The p38 inhibitor SB203580 and the PKC inhibitors Calphostin C and G?6976 completely inhibited IL-1-induced IL-6 production. Quercetin 1-100 microM inhibited IL-1-induced IL-6 secretion, p38 and PKC-theta phosphorylation in a dose-dependent manner. These results indicate that IL-1-stimulated IL-6 production from human mast cells is regulated by biochemical pathways distinct from IgE-induced degranulation and that quercetin can block both IL-6 secretion and two key signal transduction steps involved.     

Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids.

Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.