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.     

H1521, a novel derivative of 4-hydroxyquinoline-3-carboxamide, suppresses the development of lupus in mice by inducing Th1 cytokine profile in T cells

Transferring parental splenocytes into unirradiated F1 mice induces a chronic graft-versus-host disease (GVHD), characterized by the production of Th2 cytokines and immunocomplex-mediated glomerulonephritis resembling systemic lupus erythematosus (SLE). The effects of H1521, a new derivative of 4-hydroxyquinoline-3-carboxamide, were investigated in chronic GVHD lupus model. H1521 was administered to chronic GVHD mice for 10 weeks. Nephritic symptoms were monitored and cytokine expression in the spleen was detected. To clarify the direct effect of H1521 on CD4(+) T cell, CD4(+) T cells were isolated and co-cultured with H1521 under neutral and Th1 or Th2 driving conditions in vitro. H1521 (32 mg/kg) reduced the incidence of proteinuria by 50% in chronic GVHD mice. Ameliorated lupus symptoms and improved renal histopathology damage were also observed. Administration of H1521 had little impact on Th1 cytokine IL-2 and IFN-gamma or Th2 cytokine IL-4 and IL-10 mRNA expression. In contrast, severely deficient IFN-gamma production by concanavalin A-stimulated spleen cells in chronic GVHD mice was completely restored by H1521. In accordance with this, decreased T-bet mRNA expression became normalized with H1521 (32 mg/kg) treatment. In addition, in vitro studies demonstrated that H1521 preferentially favored Th1 differentiation in CD4(+) T cell and promoted IFN-gamma secretion in Th1 differential CD4(+) T cell. However, IL-4 secretion in naive or Th2 differential CD4(+) T cell was unaffected by H1521. In conclusion, H1521 can induce Th1 cytokine profile in CD4(+) T cells and has possible therapeutic value in Th2-predominant immune 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.     

Sleep-like concentrations of growth hormone and cortisol modulate type1 and type2 in-vitro cytokine production in human T cells

Slow wave sleep (SWS) is characterized by maximum release of growth hormone (GH) and minimum release of cortisol. We hypothesized that this hormonal pattern during SWS leads, in addition to generally increased T cell cytokine production, to a shift towards type1 cytokines. To test this hypothesis, blood was sampled from 8 humans during SWS, and whole blood cultures were activated in-vitro with ionomycin and phorbol-myrestate-acetate (PMA) in the absence and presence of GH neutralizing antibody (Ab) or physiological concentrations of cortisol. Production of interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-4, and tumor necrosis factor-alpha (TNF-alpha) was measured using multiparametric flow cytometry. GH Ab decreased IFN-gamma+CD4+ cells but had no effect on other cytokines. Cortisol alone and in combination with GH Ab decreased CD4+ and CD8+ cells producing IFN-gamma, TNF-alpha and IL-2. Simultaneously, these two reactants reduced IL-4+CD4+ cells, so that the ratio of IFN-gamma/IL4 producing CD4+ cells indicated an unexpected shift towards type1 dominance. Results support the view that release of GH by increasing particularly production of IFN-gamma can contribute to the shift in type1/type2 balance towards type1 activity characterizing SWS. Suppression of cortisol during this sleep period enhances both type1 and type2 activity. Yet, our finding of predominant type1 activity after cortisol administration, rules out any relevance of this suppression for the shift towards type1 activity during SWS.     

Effects of IL-12 and IL-18 on HBcAg-specific cytokine production by CD4 T lymphocytes of children with chronic hepatitis B infection

The influence of IL-12 and IL-18 was evaluated on hepatitis B core antigen (HBcAg)-specific cytokine production (IFN-gamma, IL-4, IL-5 and IL-10) by CD4 T lymphocytes isolated from peripheral blood of children with chronic hepatitis B. CD4 T cells were isolated from peripheral blood of 20 children with chronic active hepatitis B, cultured for 48h in presence of rHBcAg and of co-stimulators, IL-12 or IL-18 or IL-12+IL-18 or in their absence (control). Production of studied cytokines was examined using the ELISPOT assay. Co-stimulation with IL-12 or IL-18 was found to significantly augment the HBcAg-specific secretion of IFN-gamma. However, the most pronounced stimulatory effect was observed in the presence of IL-12+IL-18 and resulted in peak levels of IFN-gamma production. The obtained results allowed concluding that the anti-HBV activity of Th1 lymphocytes is strongly induced by IL-12+IL-18 and may contribute to viral clearance in children with chronic hepatitis B infection.     

Estradiol enhances capacity of TLR-matured splenic dendritic cells to polarize CD4+ lymphocytes into IL-17/GM-CSF-producing cells in vitro

There are little data on modulatory effects of estrogens on rat dendritic cell (DC) responses to inflammatory stimuli, and consequently their ability to activate and polarize CD4+ T lymphocyte-mediated immune responses. Splenic conventional DCs from young female Albino Oxford rats were activated in vitro with LPS (TLR4 agonist) or R848 (TLR7/8 agonist) in the presence and absence of 17β-estradiol (E2), and their allostimulatory and CD4+ lymphocyte polarizing ability in mixed leukocyte culture (MLC) were studied. Irrespective of the E2 presence, LPS and R848 up-regulated the expression of MHC II on DCs, so they exhibited enhanced allostimulatory capacity in co-culture with CD4+ lymphocytes. On the other hand, E2 promoted stimulatory action of both TLRs on OX62+ DC IL-23 production, augmented their stimulatory effects on IL-6 and IL-1β production, but diminished their enhancing effects on the expression IL-10 and IL-27 by DCs. Consequently, in MLC, OX62+ DCs activated/matured in the co-presence of E2 and either LPS or R848 increased the levels of IL-17, the signature Th17 cell cytokine, when compared with those activated/matured in the absence of E2. GM-CSF levels were also increased in these MLC. Given that the expression of IL-7 mRNA was diminished in DCs activated/matured in the co-presence of E2 and TLR, this increase most likely did not reflect enhanced differentiation of Th cells producing GM-CSF only (Th-GM).ConclusionsE2 augments capacity of LPS- and R848-activated/matured DCs from young rat spleen to induce differentiation of IL-17- and GM-CSF-producing cells.     

Hypothemycin inhibits the proliferative response and modulates the production of cytokines during T cell activation

Hypothemycin, a resorcylic acid lactone antibiotic, was identified as active in a screen for inhibitors of T cell activation. It was found to inhibit the proliferation of mouse and human T cells stimulated with anti-CD3 mAb + PMA and of human PBMC stimulated with anti-CD3 mAb alone. This inhibition was partially reversed by exogenous IL-2 indicating that it is not due to non-specific toxicity. Hypothemycin potently suppressed the production of IL-2 (IC50: 9 nM) but affected IL-2-induced proliferation to a lesser extent (IC50: 194 nM). Hypothemycin also inhibited IL-6, IL-10, IFN-gamma and TNF-alpha production. By contrast, it markedly enhanced the production of IL-4, IL-5 and IL-13. These effects were seen both at the mRNA and protein secretion levels. Analysis of the effect of hypothemycin on CD69 induction suggested that it disrupts calcineurin-independent rather than calcineurin-dependent signaling. Furthermore, hypothemycin was able to inhibit the phosphorylation of ERK1/2 induced by PMA treatment of T cells. Therefore, hypothemycin represents an inhibitor of T cell activation with a novel mode of action and unique modulatory activity on cytokine production.     

Activation of human monocyte-derived dendritic cells in vitro by the biological response modifier arabinoxylan rice bran (MGN-3/Biobran)

Arabinoxylan rice bran (MGN-3/Biobran) is a potent biological response modifier (BRM) that activates natural killer (NK) cells, T cells and monocytes. Currently, little is known regarding the effects of MGN-3 on dendritic cells (DCs), the cell type that bridges innate and adaptive immunity. Therefore, we examined the stimulatory effects of MGN-3 on DCs. Human monocyte-derived DCs were treated with MGN-3 at different concentrations (5-20 microg/ml) for 24 hours in vitro. Activation of DCs was determined by assessing the expression of co-stimulatory and maturation markers (CD40, CD80, CD83, CD86 and HLA-DR) by flow cytometry, and production of cytokines by ELISA. DC function was determined by assessing their ability to activate na?ve T cells. Activation of T cells was assessed by measuring cell proliferation and cytokine production. MGN-3 treatment, in a dose-dependent manner, resulted in: 1) up-regulation of the surface expression of CD83 and CD86, on DCs; 2) an increase in the production of pro-inflammatory and immuno-regulatory cytokines (IL-1beta, IL-6, IL-10, TNF-alpha, IL-12p40 and low levels of IL-12p70 and IL-2) by DCs; and 3) MGN-3 stimulated DC induced CD4+T cell proliferation and their production of cytokines, IFN-gamma, IL-10, IL-17. Results suggest that MGN-3 functions as a natural adjuvant for DC activation and thus may be used in DC-based vaccine strategies against infections and cancer.     

Differential regulation of CD3- and CD28-induced IL-2 and IFN-gamma production by a novel tyrosine kinase inhibitor XR774 from Cladosporium cf. cladosporioides

Inhibition of CD28 signalling after an immune response impedes T cell activation and can lead to immunosuppression. To identify inhibitors of anti-CD28 induced IL-2 production, a library of fungal metabolites was screened in a cell-based, high throughput assay. A reduced novel benzofluoranthene, tentatively named as (6bS, 7R, 8S)-7-methoxy-4, 8, 9-trihydroxy-1, 6b, 7, 8-tetrahydro-2H-benzo[j] fluoranthen-3-one (XR774), from Cladosporium cf. cladosporioides, was isolated. XR774 inhibited IL-2 mRNA and protein expression induced by anti-CD28 and anti-CD3 but had no effect on IL-2 induction by PMA and ionomycin. Moreover, XR774 inhibited the activity of the tyrosine kinases, Fyn, Lck, Abl and epidermal growth factor receptor (EGFR) with nanomolar activity, whereas micromolar concentrations of XR774 were ineffective on the serine-threonine kinase, PKA. Kinetic analysis of Fyn kinase inhibition was consistent with XR774 as a competitive inhibitor with respect to ATP. In peripheral blood, mononuclear cells (PBMC), XR774 inhibited anti-CD3 and anti-CD28 induced IL-2 and IL-2R alpha chain (CD25) expression but was consistently less active for inhibition of IFN-gamma production. On stimulation with PMA and anti-CD28, XR774 inhibited IL-2 production but had no effect on CD25 expression and enhanced IFN-gamma production. In contrast, the ansamycin, geldanamycin, inhibited both IL-2 and IFN-gamma production induced by anti-CD3 and anti-CD28 or PMA and anti-CD28. No significant associated cytotoxicity or inhibition of protein synthesis was observed at concentrations up to 14 microM. Thus, XR774 represents a novel class of pharmacological agent with selective biological activities that distinguish it from other natural product inhibitors, such as the ansamycins.     

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.     

Quantitation of immunosuppression by tacrolimus using flow cytometric analysis of interleukin-2 and interferon-gamma inhibition in CD8(-) and CD8(+) peripheral blood T cells

The authors have determined the frequency of intracellular interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) synthesis by T-cell subsets in whole blood (WB) and isolated lymphocytes in 16 transplant recipients treated with tacrolimus and 10 control patients who were not transplant recipients. The authors also determined the impact of varying amounts of red blood cells (RBC) on immunosuppression by tacrolimus. Samples were analyzed by two-color flow cytometry, and the results were expressed as a ratio of whole blood to isolated lymphocytes. In healthy subjects who were not transplant recipients, the frequency of IL-2--producing CD8(-) and CD8(+) cells was higher in WB than in isolated lymphocytes (mean +/- SD of whole blood to lymphocytes ratio: 1.24 +/- 0.5 and 1.67 +/- 0.62, respectively). Adding varying amounts of RBC had no significant impact on IL-2 production by CD8(-) and CD8(+) T cells. Adding tacrolimus (10 ng/mL) to lymphocyte cultures inhibited (90%) IL-2 production in isolated T cells but not in the whole-blood assay. The dose of tacrolimus required for a 50% inhibition of IL-2 release in T cells was 10-fold higher in cultures with RBC than without. Peripheral blood mononuclear cells (PBMC) isolated from tacrolimus-treated whole blood (WB) showed less IL-2 inhibition than did lymphocytes in the WB. The authors also tested cytokine production in WB and PBMCs in 16 transplant recipients and observed various patterns of reactivity. The frequency of IL-2--producing CD8(-) and CD8(+) cells was similar using two different methods in 10 of 16 patients tested. By contrast, in the remaining six patients the authors observed a significant inhibition of IL-2 production in both CD8(-) and CD8(+) T-cell subsets in the whole-blood assay but not in the isolated lymphocytes. The frequency of CD8(-) IFN-gamma--producing cells was significantly lower in 9 of 16 patients, but the same individuals showed no inhibition of their CD8(+) IFN-gamma T cells. The trough levels of tacrolimus did not predict the level of cytokine inhibition in the whole-blood assay in these patients. The authors' results show that the whole-blood assay for cytokine production can be used for monitoring the in vivo effect of tacrolimus in transplant recipients.     

肌肉注射白介素-10质粒DNA预防小鼠自身免疫性糖尿病

目的:研究编码白介素-10(IL-10)质粒DNA对由多次、低剂量链脲佐菌素(STZ)诱发的自身免疫性糖尿病小鼠的作用。方法:连续5天将STZ(每次40 mg/kg)腹腔注射入小鼠体内,于第1、14天将100 mg表达人IL-10-pcDNA3质粒(IL-10处理组)或pcDNA3质粒(对照组)注射入骨骼肌内。测定小鼠血糖水平。第28天处死小鼠,检测小鼠血清干扰素-γ(IFN-γ)水平、胰腺IL 1β和TNF-α mRNA表达,测定脾CD4~+和CD8~+淋巴细胞的数量,同时进行胰腺组织学检查。结果:IL-10质粒DNA注射后,骨骼肌有IL-10 mRNA的持久表达,血浆IL-10水平明显升高,而且对迟发性超敏反应具抑制作用。IL-10处理组,在14、21和28天小鼠血糖显著降低,在21、28天时糖尿病发病率分别为33.3％和40.0％,显著低于对照组(P<0.05);胰腺IL-1β和TNF-αmRNA表达、血清IFN-γ水平,以及脾CD4~+和CD8~+淋巴细胞数量均低于对照组,胰岛炎症程度也明显轻于对照组(P<0.01)。结论:IL-10基因治疗能减轻实验性自身免疫性糖尿病小鼠 的胰岛炎症,降低糖尿病发生的机率。     

High intracytoplasmatic levels of Il-4 and Il-5 in a patient with Gleichs syndrome: case report

Gleichs syndrome is characterized by recurrent localized angioedema, hypereosinophilia, elevated levels of IgM, rapid weight gain, itchy urticaria and fever. Little is known about the pathogenesis of this disease. Increased serum levels for IL5, IL6 and C5a have been reported before and during clinical exacerbations. In order to better understand the role of the T cells in Gleichs syndrome we analyzed the intracellular cytokine expression in CD3+ cells of a patient affected by the disease. As hypereosinophilia was documented, we asked whether IL-4 and IL-5 levels were increased, and the intracytoplasmatic expression of these Th2-cytokines was determined. The percentage of T lymphocytes (CD3-gated cells) of both CD8- and CD8+ phenotype expressing different cytokines showed an unusually high percentage of Th2-related cytokine (IL-4, IL-5 and IL-13) expressing T lymphocytes. The two new variants (myeloproliferative and lymphoproliferative) seem to account for hypereosinophilia in patients with hypereosinophilic syndrome (HES). In the lymphroliferative variant, the presence of a clonal CD3-CD4+ Th2 like lymphocyte secreting IL-4 and IL-5 in peripheral blood, may explain the hypereosinophilia and the hyper-IgE. In our study we show that the patient had a lymphoproliferative variant and her T cell had a Th2 type phenotype. Moreover, we suggest that Th2 lymphocytes may play a role in the pathogenesis of Gleichs syndrome. Further studies are needed to evaluate the possibility that a polyclonal aspecific activation of Th2 type cells can lead to hypereosinophilia, IgE production and the other manifestations typical of Gleichs syndrome.     

Effects of the kinase inhibitor CGP41251 (PKC 412) on lymphocyte activation and TNF-alpha production

CGP41251 is a serine/threonine and tyrosine kinase inhibitor that is a novel anticancer agent. Because the kinases that CGP41251 inhibits play important roles in T lymphocyte activation, we hypothesized that this compound may have useful immunomodulatory properties. Here we characterized the in vitro immunomodulatory effects of CGP41251. The effects of CGP41251 on lymphocyte proliferation, expression of T cell activation surface markers, and intracellular calcium response in peripheral blood mononuclear cells (PBMC's) were measured. Intracellular IL-2, TNF-alpha, IFN-gamma expression in CGP41251-treated T cells stimulated by lectin was measured by flow cytometry. CGP41251 inhibited lectin-induced lymphocyte proliferation and upregulation of activation surface markers with a 50% inhibitory concentration (IC(50)) of 0.1 microM. CGP41251, at micromolar concentrations, blunted the intracellular calcium response during PBMC activation. CGP41251 inhibited TNF-alpha production by T cells with an IC(50) of 0.5 microM and did not significantly inhibit the production of IL-2 or IFN-gamma. In conclusion, CGP41251 potently inhibits T lymphocyte activation and function and interferes with the proximal part of the T cell activation pathway. The ability of CGP41251 to selectively block T cell TNF-alpha production warrants the evaluation of this compound on other, e.g., monocyte, immune cells and in immunological conditions that are characterized by high TNF-alpha levels such as psoriasis and inflammatory bowel diseases.