A selective phosphodiesterase 4 (PDE4) inhibitor Zl-n-91 suppresses IL-17 production by human memory Th17 cells

Th17 cells are highly proinflammatory and involved in the immunopathogenesis of severe autoimmune diseases. Selective phosphodiesterase 4 (PDE4) inhibitors, which elevate intracellular cAMP by inhibiting the hydrolysis of cAMP, have been demonstrated to be an effective anti-inflammatory agent in airway inflammatory diseases. In the present study, we assessed the effect of a selective PDE4 inhibitor Zl-n-91 on IL-17 production by PBMCs and by purified CD4(+) T cells following stimulation. The results for the first time demonstrated that the addition of Zl-n-91 into cell cultures of PBMCs and purified CD4(+) T cells could result in the suppression of IL-17 production at the protein and mRNA levels. Further analysis indicated that Zl-n-91 had a direct inhibitory effect on the IL-17 production by memory Th17 cells via the suppression of activation, proliferation and division of CD4(+) T cells. Our data suggested that Zl-n-91 might have beneficial effects in the treatment of IL-17-related autoimmune diseases.     

Exposure to particulate matter 2.5 (PM2.5) induced macrophage-dependent inflammation,characterized by increased Th1/Th17 cytokine secretion and cytotoxicity

Particulate matter PM2.5 is a class of airborne particles and droplets with sustained high levels in many developing countries. Epidemiological studies have shown the association between sustained high level of PM2.5 and the risk of many diseases in the respiratory system, including lung cancer. However, the precise mechanisms through which PM2.5 induces respiratory diseases are still unclear. In this study, we demonstrated that CD4⁺ and CD8⁺ T cells following PM2.5 treatment demonstrated significantly elevated mRNA and protein levels of interferon (IFN)-γ, interleukin (IL)-10, IL-17, and IL-21 production. This increase in cytokines required the presence of macrophages, such that CD4⁺ and CD8⁺ T cells treated with PM2.5 in the absence of macrophages did not present higher IFN-γ, IL-10, or IL-21 expression. In contrast, PM2.5-treated macrophages could significantly upregulate T cell cytokine secretion, even when excess PM2.5 was removed from cell culture. We also observed a macrophage-dependent upregulation of granzyme A and granzyme B expression by CD4⁺ and CD8⁺ T cells following PM2.5 treatment. These PM2.5-stimulated CD4⁺ and CD8⁺ T cells potently induced the death of human bronchial epithelial (HBE) cells. Interestingly, the CD4⁺ and CD8⁺ T cells presented synergistic effects at inducing HBE cytotoxicity, such that CD4⁺ T cells and CD8⁺ T cells combined resulted in higher HBE cell death than the sum of the separate effects of CD4⁺ T cells and CD8⁺ T cells. While blocking cytotoxic molecule release significantly compromised the T cell-mediated cytotoxicity against HBE cells, blocking IFN-γ, but not IL-10, could also slightly but significantly reduce T cell-mediated cytotoxicity. Together, these data demonstrated that PM2.5 could promote the inflammation of cytotoxicity of T cells in a macrophage-dependent manner. In addition, PM2.5-treated macrophages presented long-lasting proinflammatory effects on T cells.     

Non-antibiotic properties of tetracyclines as anti-allergy and asthma drugs

All available therapies for human allergic disease target IgE mediated pathologic responses after IgE has been produced. We are developing tetracyclines as anti-allergy drugs to prevent IgE production, based on our findings that minocycline or doxycycline treatment of allergic asthmatic humans significantly improves their asthma symptoms, reduces their oral steroid requirements, and strongly suppresses their ongoing IgE responses (ELISA, mast cell mediated cutaneous late phase responses); the tetracyclines also strongly suppress peak IgE responses of BPO-KLH sensitized mice (ELISPOT assay, ELISA, skin tests). The antibiotic activity of the tetracyclines is not required for suppression of IgE responses; inclusion of minocycline or doxycycline in sterile culture prevents anti-CD40/IL-4 mediated induction of memory IgE responses by PBMC of allergic asthmatic patients (ELISA), and induction of specific memory IgE responses by spleen cells of BPO-KLH sensitized mice (ELISPOT assay, ELISA). The tetracyclines affect an epsilon specific pathway because IgM, IgG and IgA responses did not decrease. Further, in humans, DTH responses to recall antigens did not decrease. In related studies, we found that two distinct T cell subsets: CD4+CD60 negative and CD8+CD60+ (CD60 is a ganglioside) (humans) and CD4+ Asialo GM1 ganglioside negative and CD8+Asialo GM1 ganglioside+ (mice), both are required for induction of memory IgE responses. Phosphorylated (phos) p38 MAP kinase, but not phos ERK or phos JNK expression by CD4+ and CD8+, including CD8+CD60+, T cells is increased in allergic asthmatic humans, as is IL-4 and IL-10 production. The tetracyclines appear to target T cell pathways to induce suppression of IgE responses because they suppress phos p38 MAP kinase expression by both CD4+ and CD8+, including CD8+CD60+, T cell subsets, and IL-4 and IL-10, while upregulating IL-2 and IFN gamma, and suppressing IgE responses. Our finding that tetracyclines do not require antibiotic activity to suppress IgE responses opens the door to development of new tetracycline-based and other therapeutics for human allergic disease.     

Modulation of Th2 type cytokine production from human peripheral blood leukocytes by a macrolide antibiotic, roxithromycin, in vitro

The influence of a macrolide antibiotic, roxithromycin (RXM), on Th1 and Th2 cytokine productions from human peripheral blood T cells was examined under stimulation with co-stimulatory molecules. Peripheral blood T cells prepared from both healthy and allergic rhinitis donors were cultured in the presence of RXM on anti-CD3 mAb and anti-CD26 mAb-coated wells, anti-CD3 mAb and anti-CD28 mAb-coated wells, and anti-CD3 and PMA. T-cell proliferation, along with the concentration of interleukin (IL)-2, interferon (IFN)-gamma, IL-4 and IL-5 were measured. RXM did not affect T-cell proliferation induced by several ways of co-stimulatory activation as assessed by 3H-thymidine incorporation into DNA. RXM also had no effect on IL-2 and IFN-gamma secretion by T cells prepared from both healthy and allergic rhinitis donors. On the other hand, RXM markedly inhibited both IL-4 and IL-5 secretions under each of the co-stimulatory conditions in a dose-dependent manner. These results indicate that RXM inhibits specifically Th2 cytokine secretion from T cells induced by co-stimulatory molecule stimulations. This inhibitory action of RXM may be partially responsible for attenuating effect of the agent on the inflammatory diseases.     

The regulation of CD4+ T cell immune responses toward Th2 cell development by prostaglandin E2

As an important immune mediator, PGE2 plays an important role in the immune tolerance, autoimmune diseases, immune regulation and tumor immunotolerance. PGE2 is considered to be a promising candidate for the control of the immune diseases. To further understand the immuno-modulating effects of PGE2 on CD4+ T cells, in vitro investigation was conducted in the present study. The results showed that PGE2 inhibited the proliferation of T cells in vitro in a dose-dependent manner. Gene expression profiling showed that 1716 genes were down regulated and 73 genes were up regulated with a change of 1.5 fold. Several signal transduction pathways were involved, such as TNF-α and NF-kB signaling pathway, T cell receptor signaling pathway, IL-2 signaling pathway, and MAPK pathway. The results showed that PGE2 inhibited IFN-γ, TNF-α and IL-4 production by CD4+ T cells 24 h after cell culture. A comparison between IFN-γ and IL-4 production showed that PGE2 enhanced the relative ratio of IL-4 to IFN-γ in CD4+ T cells culture, and regulated CD4+ T cells toward Th2 cell development. The results of the present study indicated that PGE2 has the potential to treat Th1-mediated inflammatory diseases by regulating CD4+ T cells toward Th2 cell immune response.     

Rottlerin inhibits human T cell responses

Rottlerin is a pharmacological inhibitor of protein kinase C (PKC) theta, a novel PKC selectively expressed in T lymphocytes. PKC theta is known to regulate T cell receptor (TCR)/CD28 signalling pathways in T lymphocytes, but the impact of PKC theta inhibition on human T cell responses remains undefined. In this work, we describe the effects of rottlerin on the responses of CD4+ and CD8+ human T lymphocytes upon polyclonal activation. We observed a dose-dependent inhibition of CD4+ and CD8+ T cell proliferation in response to anti-CD3/anti-CD28 antibodies stimulation in the presence of rottlerin. This inhibition was associated with impaired CD25 expression and decreased interleukin (IL)-2 production in activated T cells. In contrast, rottlerin did not alter IL-2-induced T cell proliferation. Furthermore, we demonstrated that rottlerin blocked interferon (IFN) gamma, IL-10 and IL-13 mRNA expression in TCR/CD28 activated CD4+ T cells. These findings place rottlerin as a potent immunosuppressive agent for the development of novel therapies in T cell mediated immune disorders.     

Inhibition of interleukin-12 production by auranofin, an anti-rheumatic gold compound, deviates CD4(+) T cells from the Th1 to the Th2 pathway

1. Interleukin-12 (IL-12) may play a central role in the development and progression of rheumatoid arthritis by driving the immune response towards T helper 1 (Th1) type responses characterized by high IFN-gamma and low IL-4 production. In this study we investigated the effect of auranofin (AF), an anti-rheumatic gold compound, on IL-12 production in mouse macrophages and dendritic cells, and studied whether AF-mediated inhibition of IL-12 production could regulate a cytokine profile of antigen (Ag)-primed CD4(+) Th cells. 2. Treatment with AF significantly inhibited IL-12 production in lipopolysaccharide (LPS)-stimulated macrophages and also in CD40L-stimulated dendritic cells. AF-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4(+) T cells. AF did not influence the cell surface expression of the class II MHC molecule and the costimulatory molecules CD80 and CD86. 3. Addition of recombinant IL-12 to cultures of AF-pretreated macrophages and CD4(+) T cells restored IFN-gamma production in Ag-primed CD4(+) T cells. 4. The in vivo administration of AF resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with LPS or heat-killed Listeria monocytogenes (HKL), leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in Ag-primed CD4(+) T cells. 5. These findings may explain some known effects of AF including anti-rheumatic effects and the inhibition of encephalitogenicity, and point to a possible therapeutic use of AF in the Th1-mediated immune diseases such as autoimmune diseases.     

Curcumin inhibits Th1 cytokine profile in CD4+ T cells by suppressing interleukin-12 production in macrophages.

1 Interleukin-12 (IL-12) plays a central role in the immune system by driving the immune response towards T helper 1 (Th1) type responses which are characterized by high IFN-gamma and low IL-4 production. In this study we investigated the effects of curcumin, a natural product of plants obtained from Curcuma longa (turmeric), on IL-12 production by mouse splenic macrophages and the subsequent ability of these cells to regulate cytokine production by CD4+ T cells. 2 Pretreatment with curcumin significantly inhibited IL-12 production by macrophages stimulated with either lipopolysaccharide (LPS) or head-killed Listeria monocytogenes (HKL). 3 Curcumin-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4+ T cells. Addition of recombinant IL-12 to cultures of curcumin-pretreated macrophages and CD4+ T cells restored IFN-gamma production in CD4+ T cells. 4 The in vivo administration of curcumin resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with either LPS or HKL, leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in CD4+ T cells. 5 These findings suggest that curcumin may inhibit Th1 cytokine profile in CD4+ T cells by suppressing IL-12 production in macrophages, and points to a possible therapeutic use of curcumin in the Th1-mediated immune diseases.     

1,25-dihydroxyvitamin D3 and dexamethasone increase interleukin-10 production in CD4+ T cells from patients with Crohn's disease

BACKGROUND AND AIM: In Crohn's disease (CD), epidemiological data and animal studies suggest that vitamin D (vitD) has protective immune-modulating properties. 1,25-dihydroxyvitamin D3 and dexamethasone (DEX) induce interleukin (IL)-10 productions in healthy controls (HC) T cells. We studied if 1,25-dihydroxyvitamin D3 with and without DEX could induce IL-10 production, downregulate pro-inflammatory Interferon (IFN)-gamma and Tumor Necrosis Factor (TNF)-alpha production, and influence cell kinetics in peripheral CD4+ T cells from CD patients. METHODS: CD4+ T cells were separated from peripheral blood from CD patients and HC. Cells were activated by anti-CD3 and anti-CD28 in the presence of 1,25-dihydroxyvitamin D3 and/or DEX. Cytokine levels, proliferation, and apoptosis were measured following 7 days of culture. RESULTS: In T cells from CD patients, 1,25-dihydroxyvitamin D3 and DEX increased IL-10 production from a median of 0.08 ng/ml to 0.2 ng/ml (p<0.01) and downregulated IFN-gamma production from 8.3 ng/ml to 3.1 ng/ml (p<0.01). The induced IL-10 increase in cultures from HC (0.2 ng/ml to 1.0 ng/ml, p<0.01) was significantly higher than in CD patients (p<0.05). In CD cultures, the IL-4 production increased from 0.3 ng/ml to 0.5 ng/ml (p<0.01) and IL-6 production from 2.5 ng/ml to 6.1 ng/ml (p<0.05). Similar changes in cytokine levels were observed with 1,25-dihydroxyvitamin D3 independently of DEX. In addition, 1,25-dihydroxyvitamin D3 and DEX decreased proliferation and reduced viability of T cells. CONCLUSION: We found that 1,25-dihydroxyvitamin D3 with and without DEX stimulation increased IL-10 and reduced IFN-gamma production. These findings suggest that vitD may play a therapeutic role in CD.     

Modulation of phenotype, cytokine production and stimulatory function of CD34+-derived DC by NiCl(2) and SDS.

One of the most promising alternatives to identify the sensitizing potency of new products is the in vitro culture of human dendritic cells (DC). In vivo, dendritic cells present in the skin are highly specialized antigen-presenting cells (APC) of the immune system, which play a crucial role in the induction of allergic reactions. The DC produce specific cytokines and upregulate specific co-stimulatory molecules in addition to the antigen-MHC complex in order to promote an optimal T-cell activation. The aim of our study is to assess the phenotype, cytokine production and autologous T-cell stimulatory capacity of the in vitro CD34+-derived dendritic cells after 24 hours of incubation with the metal allergen NiCl(2) (100-300 microM) and the irritant sodium dodecyl sulfate (SDS; 0.01%), in order to find a sensitive endpoint to discriminate between sensitizers and irritants. After exposure to Ni, a significant increase in the number of CD83+ and CD86+ cells was noticed. The intensity of CD86 as well as the intensity of the HLA-DR molecule on the DC also showed a significant increase. The expression of the co-stimulatory molecule CD80 was not changed after exposure. SDS was not able to increase the expression of any of the analysed markers. The production of IL-6 increased significantly after exposure of dendritic cells to Ni, but not after SDS exposure. Results on tumor necrosis factor-alpha (TNF-alpha) production are somewhat equivocal. Although not statistically significant, TNF-alpha was upregulated in one out of three experiments after 48 hours of exposure to the Ni allergen, but increases were also noticed after exposure to SDS (two out of three experiments). Both exposure to Ni and SDS caused an upregulation (not significant) in the IL-12 production by DC, but the production was higher in Ni-exposed DC compared to SDS-exposed cells. In none of the exposed DC cultures was it possible to detect IL-1 beta. The antigen-presenting capacity of the DC in autologous MLR could not be demonstrated. Nevertheless, T-cell proliferation after DC stimulation was noticed in allogenic MLR.     

Regulation of IL-13 synthesis in human lymphocytes: implications for asthma therapy

1. IL-13 is an important mediator in inflammatory diseases such as asthma. IL-13 is mainly produced by T cells. However, signalling pathways leading to induction of this cytokine are not well-characterized. We analysed the regulation of IL-13 in human peripheral blood mononuclear cells and CD4(+) T cells. 2. Cyclosporine (CsA) and FK-506 inhibited IL-13 synthesis, when cells were stimulated by TPA/ionomycin. However, stimulation by alpha-CD3/alpha-CD28 led to an enhanced IL-13 synthesis. 3. NF-kappa B inhibitor N-tosyl-L-lysine chloromethylketone (TLCK) inhibited IL-13 synthesis more effectively after TPA/ionomycin stimulation. After alpha-CD3/alpha-CD28 stimulation, only 300 microM TLCK inhibited IL-13 synthesis. Dexamethasone inhibited IL-13 equally effective after alpha-CD3/alpha-CD28 and TPA/ionomycin stimulation. 4. p38 MAPK inhibitor SB203580 inhibited IL-13 synthesis only partially. MEK inhibitor U0126 inhibited TPA/ionomycin induced IL-13 synthesis very effectively, whereas alpha-CD3/alpha-CD28 stimulated IL-13 induction was resistant to this drug. 5. These results were confirmed in purified CD4(+) T cells. In difference to PBMCs alpha-CD3/alpha-CD28 stimulated IL-13 synthesis was effectively inhibited by CsA, FK-506 and U0126. 6. Therefore U0126 was tested in an animal model of allergic asthma. We could demonstrate for the first time that inhibition of the MEK - ERK cascade is a therapeutic option for asthma. Intraperitoneal administration of 10 mg kg(-1) U0126 reduced lung eosinophilia in ovalbumin-challenged Brown Norway rats by 44%. 7. These results demonstrate that different signalling pathways are involved in regulating IL-13 synthesis in primary human T cells. Characterizing highly potent inhibitors of IL-13 synthesis can be exploited to identify new drugs to treat immunological diseases such as asthma.     

Effects of FK506 and other immunosuppressive anti-rheumatic agents on T cell activation mediated IL-6 and IgM production in vitro

The objective of this study was to investigate the therapeutic potential of FK506 and other immunosuppressive agents for the treatment of rheumatoid arthritis (RA), focusing on the effects on in vitro IL-6 production and IL-6-mediated immune response. We employed an in vitro model producing IL-6 via T cell activation in human PBMC, based on the hypothesis that T cells play a central role in the pathogenesis of RA. FK506 potently inhibited IL-6 production from PBMC stimulated with anti-CD3 and anti-CD28 monoclonal antibody (anti-CD3/CD28). Cyclosporin A (CsA) also inhibited the anti-CD3/CD28 induced IL-6 production but was about 100 times less potent than FK506. Dexamethasone (DEX) inhibited both anti-CD3/CD28 and LPS induced IL-6 production at almost the same concentration. Methotrexate (MTX) did not affect cytokine production. Anti-CD3/CD28 stimulated PBMC culture supernatants were found to enhance IgM production in SKW6.4 cells. The effects of anti-CD3/CD28 stimulated culture supernatants in the presence of agents on IgM production in SKW6.4 cells were investigated. FK506 and CsA led to suppression of IgM production induced by culture supernatants probably via inhibition of IgM inducible cytokine production from PBMC. DEX profoundly enhanced IgM production, although IL-6 production from PBMC was strongly inhibited by the agent. MTX decreased IgM production although it has no inhibitory effect on IL-6 production. The present study suggests that FK506 is the most effective among the four agents for the suppression of IL-6 production and IL-6-mediated autoantibody production in T cell activation related autoimmune diseases such as RA.     

Paeoniflorin inhibits the maturation and immunostimulatory function of allergen-induced murine dendritic cells

Dendritic cells (DCs) as the front lines of defense play a crucial role in allergic contact dermatitis (ACD). Paeoniflorin (PF) has been clinically proven to be effective in the treatment of inflammatory skin diseases such as ACD. However, the mechanisms underlying the anti-inflammatory effect of PF remain unclear. The aim of this study was to explore the effect of PF on the maturation and immunostimulatory function of DCs in the murine model of ACD in vitro. Murine bone marrow-derived DCs were stimulated with the contact sensitizer 1-chloro-2, 4-dinitrobenze (DNCB) in vitro. Surface antigen expression of DCs (MHC II, CD40, CD80, and CD86), as an indicator of maturation DCs and cytokines (IL-12, IFN-γ, IL-10, and TGF-β) after DNCB stimulation in the absence or presence of PF at different doses, was detected. Then, we detected that PF-treated DCs stimulated T cells in response to DNCB. PF inhibited the up-regulation of MHC II, CD80, CD86, and CD40, decreased IL-12p70 secretion, while increased the production of IL-10 and TGF-β, and had no effect on IFN-γ cytokine production by murine bone marrow-derived DCs in response to DNCB. DCs exposed to PF had diminished capacity to stimulate allogeneic T cell proliferation and to activate IFN-γ-producing CD4⁺ T cells and induced CD4⁺CD25⁺Foxp3⁺ T cells and IL-10-producing T cell expansion from naïve CD4⁺ T cells. These results indicate that PF may be effective in preventing and treating ACD in vitro and other inflammatory responses possibly through inhibiting maturation of DCs and limiting their capacity to stimulate T cell responses.     

Interleukin-21 in immune and allergic diseases

Interleukin-21 (IL-21), a cytokine produced by various subsets of activated CD4+ T cells, plays a major role in the control of innate and adaptive immune responses. IL-21 biological activity is mediated by binding of the cytokine to a heterodimeric receptor, composed of a specific subunit, termed IL-21 receptor (IL-21R), and the common γ-chain, that is shared with IL-2, IL-4, IL-7, IL-9 and IL-15 receptors. IL-21 stimulates the proliferation of CD4+ and CD8+ T lymphocytes and regulates the profile of cytokines secreted by these cells, drives the differentiation of B cells into memory cells and Ig-secreting plasma cells, and enhances the activity of natural killer cells. IL-21 controls also the activity of non-immune cells, such as epithelial cells and stromal cells. The demonstration that IL-21 is involved in the immune responses occurring in chronic inflammatory and allergic diseases suggests that either disrupting or enhancing IL-21 signalling may be useful in specific clinical settings.     

Anti-inflammatory action of Cudrania tricuspidata on spleen cell and T lymphocyte proliferation

This study examined whether an extract of Cudrania tricuspidata shows anti-proliferative effects in anti-CD3/CD28-mediated spleen and CD4+CD25- T cells and decreases the production of the proinflammatory cytokines interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) in anti-CD3/CD28-mediated CD4+CD25- T cells. The proliferation of anti-CD3/CD28-mediated spleen cells and CD4+CD25- T cells was effectively suppressed by C. tricuspidata. This extract, however, did not show cytotoxicity in spleen cells under conditions where the antigen was not stimulated using CCK-8 analysis. C. tricuspidata also decreased the production of the pro-inflammatory cytokines IL-2 and IFN-gamma by selective inhibition of this extract on proliferating cells in anti-CD3/CD28-mediated CD4+CD25- T cells. These results suggest that C. tricuspidata may be useful in the treatment of autoimmune diseases and organ transplantation through the inhibitory action of T cells in inflammation.     

The Role of TARC in the Pathogenesis of Allergic Asthma

TARC (thymus and activation-regulated chemokine), as a selective chemoattractant of Th2 cells, is a reasonable candidate as a key regulator of Th2-mediated inflammation in allergic asthma. Studies have determined that TARC is up-regulated in the airways of human subjects with asthma and that CCR4- and CCR8-bearing T cells are also present in the airways of asthmatic subjects after allergen challenge. Mouse models of allergic airway inflammation have shown that neutralization of TARC can not only inhibit T-cell and eosinophil infiltration into the lung but can also inhibit bronchial hyperresponsiveness. The exact mechanism by which TARC can participate in allergic inflammation and what triggers the expression of TARC following allergen exposure is still unknown. Studies suggest that it could be involved not only in allergic asthma, but in the pathogenesis of allergic Th2-mediated diseases in general. (c) 2002 Prous Science. All rights reserved.     

Inhibition of lymphocyte activation and function by the prenylation inhibitor L-778,123

Prenylated Ras GTPases transduce signals from the T cell receptor, CD28 costimulatory receptor and IL-2 receptor. Since signals from these receptors mediate T cell activation, proliferation and survival, we hypothesized that the prenylation inhibitor L-778,123 would impart immunomodulation.The effect of L-778,123 on T cell activation (CD71 or CD25 surface expression) was determined by flow cytometry. Peripheral blood mononuclear cell (PBMC) proliferation in the presence of L-778,123 and/or cyclosporine (CsA) was determined by [3H]thymidine incorporation. The ability of L-778,123 to inhibit IL-2 receptor signaling was investigated by measuring IL-2 induced proliferation in CTLL-2 cells and IL-2 prevention of apoptosis in activated human PBMC. L-778,123 inhibited lectin induced expression of CD71 and CD25 with IC50's of 6.48 +/- 1.31 microM and 84.1 +/- 50.0 microM, respectively. PBMC proliferation was inhibited by L-778,123 with an IC50 of 0.92 +/- 0.23 microM, and addition of CsA did not increase the potency. L-778,123 did not inhibit IL-2 and IFN-gamma production by T cells. L-778,123 abrogated IL-2 induced proliferation of CTLL-2 cells with an IC50 of 0.81 +/- 0.44 microM. However, L-778,123 minimally reversed the prosurvival effect of IL-2 in activated lymphocytes. IL-2 ligand and receptor production during T cell activation are relatively unaffected by L-778,123. However, the activation and proliferative effects of IL-2 on T cells are potently blocked by L-778,123. These results reveal a selective blockade of the IL-2 cytokine axis distal to the IL-2 receptor by the L-778,123 and warrant evaluation of prenylation inhibitors in treating transplant rejection and autoimmune diseases.     

FK506 potently inhibits T cell activation induced TNF-alpha and IL-1beta production in vitro by human peripheral blood mononuclear cells

The aim of this study was to elucidate the in vitro inhibitory potency of FK506 on production of the inflammatory cytokines, tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta, with a view to assessing this immunosuppressive agent as a potential anti-rheumatic drug. We employed an in vitro model which produces TNF-alpha and IL-1beta through T cell activation. Human peripheral blood mononuclear cells (PBMC) were cultured with immobilized anti-CD3/CD28 monoclonal antibody in this model. FK506 inhibited anti-CD3/CD28 induced TNF-alpha and IL-1beta production at concentrations less than 1 ng ml(-1). Flow cytometric analysis of intracellular TNF-alpha and IL-1beta positive cells showed that FK506 potently suppresses inflammatory cytokine production from CD14+ monocytes as well as from T cells. Cyclosporin A (CsA) and dexamethasone (DEX) also inhibited the anti-CD3/CD28 induced cytokine production, but were less potent than FK506. FK506 and CsA, but not DEX, specifically inhibited anti-CD3/CD28 induced inflammatory cytokine production without affecting the lipopolysaccaride (LPS) induced effect. Methotrexate (MTX) was completely inactive for suppressing cytokine production under either condition. Anti-CD3/CD28 stimulated PBMC culture supernatants were found to enhance the expression of adhesion molecules in human vascular endothelial cells. FK506, CsA and DEX led to the suppression of adhesion molecule expression probably by inhibiting cytokine production from PBMC. The inhibitory potency of agents on TNF-alpha and IL-1beta production was compared with cytotoxicity and FK506 was not cytotoxic at concentrations several orders of magnitude greater than those required for cytokine inhibition. These results strongly suggest that FK506 may be most effective to specifically prevent T cell activation mediated inflammatory cytokine production in a clinical setting.     

Immunomodulatory effect of Astragali Radix extract on murine TH1/TH2 cell lineage development

Astragali Radix (AR), is a popular herbal medicine used to treat allergic diseases in Korea, Japan and China. Our study examined the effect of an AR ethanol extract on both in vitro and in vivo murine CD4 T cells' differentiation into Th1 and Th2 subsets. CD4 T cells from Balb/c mice were activated with anti-CD3/anti-CD28 mAb in the presence of AR for 2 d. AR treated cells showed an elevated level of IL-4 but a reduced level of IFN-gamma secretion. In addition, in vitro Th1/Th2 polarization experiments revealed that AR enhanced the levels of IL-4 in Th2 cells but reduced the levels of IFN-gamma in Th1 cells. To elucidate the effects of AR in Th1/Th2 lineage development during the in vivo condition, AR was administrated orally to BALB/c mice. The results demonstrated that AR administration significantly increased IL-4 production in both the serum and supernatant of splenocyte culture, while IFN-gamma secretion was diminished upon in vivo activation with anti-CD3 antibody. Our data clearly indicates that AR selectively alters Th1/Th2 cytokine secretion patterns and provides the pharmacological basis for AR's clinical applications.