Results From a First-in-Human Study of BNZ-1, a Selective Multicytokine Inhibitor Targeting Members of the Common Gamma (γc) Family of Cytokines

Pathologic roles of interleukin (IL)-2, IL-9, and IL-15, have been implicated in multiple T-cell malignancies and autoimmune diseases. BNZ-1 is a selective and simultaneous inhibitor of IL-2, IL-9, and IL-15, which targets the common gamma chain signaling receptor subunit. In this first-in-human study, 18 healthy adults (n = 3/cohort) received an intravenous dose of 0.2, 0.4, 0.8, 1.6, 3.2, or 6.4 mg/kg infused over ≤5 minutes on day 1 and were followed for 30 days for safety and pharmacokinetic/pharmacodynamic sample collection. No dose-limiting toxicities, infusion reactions, or serious or severe treatment-emergent adverse events were observed. Headache was the only treatment-emergent adverse event in >1 subject (n = 3). Peak and total BNZ-1 exposure was generally dose proportional, with a terminal elimination half-life of ∼5 days. Pharmacodynamic effects of BNZ-1 on regulatory T cells (Tregs, IL-2), natural killer (NK) cells (IL-15) and CD8 central memory T cells (Tcm, IL-15) were measured by flow cytometry and used to demonstrate target engagement. For Tregs, 0.2 mg/kg was an inactive dose, while a maximum ∼50% to 60% decrease from baseline was observed on day 4 after doses of 0.4 to 1.6 mg/kg, and higher doses produced an 80% to 93% decrease from baseline on day 15. Similar pharmacodynamic trends were observed for natural killer cells and CD8 Tcm, although decreases in CD8 Tcm were more prolonged. These subpopulations returned to/toward baseline by day 31. T cells (total, CD4, and CD8), B cells, and monocytes were unchanged throughout. These preliminary results suggest that BNZ-1 safely and selectively inhibits IL-2 and IL-15, which results in robust, reversible immunomodulation.

IL-2 and IL-15 blockade by BNZ-1, an inhibitor of selective γ-chain cytokines, decreases leukemic T-cell viability

Interleukin-15 (IL-15) and IL-2 drive T-cell malignancies including T-cell large granular lymphocyte leukemia (T-LGLL) and HTLV-1 driven adult T-cell leukemia (ATL). Both cytokines share common γ-chain receptors and downstream signaling pathways. T-LGLL is characterized by clonal expansion of cytotoxic T cells and is associated with abnormal JAK/STAT signaling. ATL is an aggressive CD4+ T-cell neoplasm associated with HTLV-1. T-LGLL and ATL share dependence on IL-2 and IL-15 for survival and both diseases lack effective therapies. BNZ-1 is a pegylated peptide designed to specifically bind the γc receptor to selectively block IL-2, IL-15, and IL-9 signaling. We hypothesized that treatment with BNZ-1 would reduce cytokine-mediated proliferation and viability. Our results demonstrated that in vitro treatment of a T-LGLL cell line and ex vivo treatment of T-LGLL patient cells with BNZ-1 inhibited cytokine-mediated viability. Furthermore, BNZ-1 blocked downstream signaling and increased apoptosis. These results were mirrored in an ATL cell line and in ex vivo ATL patient cells. Lastly, BNZ-1 drastically reduced leukemic burden in an IL-15-driven human ATL mouse xenograft model. Thus, BNZ-1 shows great promise as a novel therapy for T-LGLL, ATL, and other IL-2 or IL-15 driven hematopoietic malignancies.

Daclizumab in multiple sclerosis

INTRODUCTION

Daclizumab is a monoclonal antibody directed against the CD25 subunit of the interleukin-2 receptor, investigated as a disease-modifying therapy in relapsing-remitting multiple sclerosis. The present review addresses how the drug was developed, the known mechanism of action of the drug and the up-to-date data of efficacy and safety.

DEVELOPMENT

Daclizumab has shown superiority in prevention of relapses against placebo and low-dose interferon beta-1a at a level that puts it on par with the rest of current first-line drugs. The effect on the progression of the disease and on neurodegeneration parameters, however, is not clear. On the other hand, it presents safety problems (mainly risk of autoimmunity phenomena including fulminant hepatopathy and encephalitis) that have supposed eventually its withdrawn from marketing. Daclizumab introduces a new mechanism of action through the blocking of a key interleukin in immune regulation and its effect on a population of cells with regulatory ability, such as the NK CD56(bright) cells.

CONCLUSIONS

Daclizumab has shown efficacy in slowing the inflammatory process of multiple sclerosis, although the appearance of potentially serious side effects has not allowed its use to significantly impact current clinical practice. The development of new drugs in multiple sclerosis must be contingent on maintaining or improving the risk-benefit profile with respect to those already in use.

Guanine and inosine nucleotides/nucleosides suppress murine T cell activation

Damaged tissues and cells release intracellular purine nucleotides, which serve as intercellular signaling factors. We previously showed that exogenously added adenine nucleotide (250 μM ATP) suppressed the activation of murine splenic T lymphocytes. Here, we examined the effects of other purine nucleotides/nucleosides on mouse T cell activation. First, we found that pretreatment of mouse spleen T cells with 250 μM GTP, GDP, GMP, guanosine, ITP, IDP, IMP or inosine significantly reduced the release of stimulus-inducible cytokine IL-2. This suppression of IL-2 release was not caused by induction of cell death. Further studies with GTP, ITP, guanosine and inosine showed that pretreatment with these nucleotides/nucleosides also suppressed release of IL-6. However, these nucleotides/nucleosides did not suppress stimulus-induced phosphorylation of ERK1/2, suggesting that the suppression of the release of inflammatory cytokines does not involve inhibition of ERK1/2 signaling. In contrast to ATP pretreatment at the same concentration, guanine or inosine nucleotides/nucleosides did not attenuate the expression of CD25. Our findings indicate that exogenous guanine or inosine nucleotides/nucleosides can suppress inflammatory cytokine release from T cells, and may be promising candidates for use as supplementary agents in the treatment of T cell-mediated immune diseases.

Discovery of three toxin peptides with Kv1.3 channel and IL-2 cytokine-inhibiting activities from Non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai

Non-Buthidae venomous scorpions are huge natural sources of toxin peptides; however, only a few studies have been done to understand their toxin peptides. Herein, we describe three new potential immunomodulating toxin peptides, Ctri18, Ctry68 and Ctry2908, from two non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai. Sequence alignment analyses showed that Ctri18, Ctry68 and Ctry2908 are three new members of the scorpion toxin α-KTx15 subfamily. Electrophysiological experiments showed that Ctri18, Ctry68 and Ctry2908 blocked the Kv1.3 channel at micromole to nanomole levels, but had weak effects on potassium channel KCNQ1 and sodium channel Nav1.4, which indicated that Ctri18, Ctry68 and Ctry2908 might have specific inhibiting effects on the Kv1.3 channel. ELISA experiments showed that Ctri18, Ctry68 and Ctry2908 inhibited IL-2 cytokine secretions of activated T lymphocyte in human PBMCs. Excitingly, consistent with the good Kv1.3 channel inhibitory activity, Ctry2908 inhibited cytokine IL-2 secretion in nanomole level, which indicated that Ctry2908 might be a new lead drug template toward Kv1.3 channels. Together, these studies discovered three new toxin peptides, Ctri18, Ctry68 and Ctry2908, with Kv1.3 channel and IL-2 cytokine-inhibiting activities from two scorpions, C. tricostatus and C. tryznai, and highlighted that non-Buthidae venomous scorpions are new natural toxin peptide sources.

DNA Demethylation of the Foxp3 Enhancer Is Maintained through Modulation of Ten-Eleven-Translocation and DNA Methyltransferases

Stable expression of Foxp3 is ensured by demethylation of CpG motifs in the Foxp3 intronic element, the conserved non-coding sequence 2 (CNS2), which persists throughout the lifespan of regulatory T cells (Tregs). However, little is known about the mechanisms on how CNS2 demethylation is sustained. In this study, we found that Ten-Eleven-Translocation (Tet) DNA dioxygenase protects the CpG motifs of CNS2 from re-methylation by DNA methyltransferases (Dnmts) and prevents Tregs from losing Foxp3 expression under inflammatory conditions. Upon stimulation of Tregs by interleukin-6 (IL6), Dnmt1 was recruited to CNS2 and induced methylation, which was inhibited by Tet2 recruited by IL2. Tet2 prevented CNS2 re-methylation by not only the occupancy of the CNS2 locus but also by its enzymatic activity. These results show that the CNS2 methylation status is dynamically regulated by a balance between Tets and Dnmts which influences the expression of Foxp3 in Tregs.

Effect of Ascorbic Acid on Interleukin-2 Secretion By T Lymphocytes in Whole Blood Cultures

The effect of vitamin C on T lymphocyte function is not clear. In-vivo supplementation of vitamin C is found to have a stimulatory effect on T cells while studies in which ascorbic acid was added to T cell cultures show an inhibition of cell function. The study aims to investigate the effect of ascorbic acid on interleukin-2 secretion by T cells in whole blood cultures which better resembles the physiological environment than pure T cell cultures. It was found that ascorbic acid, when added to whole blood cultures at a very high concentration of 1 mM, inhibits interleukin-2 secretion by T cells (p<0.05). However at lower concentrations of 0.25 mM and 0.5 mM significant inhibition was not seen which is contrary to earlier reports in pure T cell cultures. Hence it can be concluded that ascorbic acid inhibits T cell function in-vitro at high concentrations but the effect is relatively less in whole blood cultures compared to pure T cell cultures.

Near-term anti-CD25 monoclonal antibody administration protects murine liver from ischemia-reperfusion injury due to reduced numbers of CD4+ T cells

Background

CD4⁺ T cell is acknowledged as a key factor in the initiation phase of liver ischemia reperfusion injury. The purpose of current study is to demonstrate the effect of antecedent near-term anti-CD25 monoclonal antibody treatment on IR-induced liver injury by modulation of CD4⁺ T cells.

Methods

70% liver warm IR was induced in male C57BL/6 mice after anti-CD25 mAb or non-specific IgG administration. Liver function, histological damage, invitro Proliferation, FACS, cytokine production, and immunofluorescence were assessed to evaluate the impact of antecedent near-term PC61 treatment on IR-induced liver injury.

Results

After 70% liver ischemia, mice preconditioned with PC61 displayed significantly preserved liver function as characterized by less histological damage and reduced serum enzymes level. Mechanistic studies revealed that the protection effect of anti-CD25 mAb was associated with ameliorated intrahepatic inflammatory milieu and reduced CD4⁺ T lymphocytes as manifested by the decrease of proinflammatory cytokine production (less expression of TNF-α, IFN-γ, IL-2, and IL-6) and the lower CD4/CD8 proportion.

Conclusions

Our results provide first line of evidence indicating that near-term treatment with anti-CD25 monoclonal antibody might provide protection for livers against IR-induced injury by reducing CD4⁺ T cells, but not influencing functional Treg population. Therefore, our results demonstrate a potential function of anti-CD25 monoclonal antibody which was neglected in the past, and may be helpful in various clinical conditions, particularly in liver and kidney transplantations.

The virulence polysaccharide Vi released by Salmonella Typhi targets membrane prohibitin to inhibit T-cell activation

T cells are critical to immunity against pathogenic Salmonella including Salmonella Typhi which causes systemic infection, typhoid, in humans. The strategies that this pathogen employs to keep T-cell mediated immune responses in check during establishment of systemic infection are not completely understood. Here, we show that the virulence polysaccharide Vi, which distinguishes S. Typhi from localized gastroenteritis-producing nontyphoidal Salmonella serovars, is a potent inhibitor of T-cell activation. Vi released by S. Typhi interacts with the membrane prohibitin complex and inhibits IL-2 secretion from T cells stimulated through the T-cell receptor (TCR) but does not affect PMA-activated interleukin 2 (IL-2) secretion. Treatment with Vi suppresses early activation events including TCR down-regulation, actin polymerization, and phosphorylation of ERK. Coadministration of Vi with anti-CD3 Ab reduces secretion of IL-2 and interferon γ in mice. Our findings reveal a mechanism by which S. Typhi may target T-cell immunity during establishment of typhoid.

Combined stimulation of IL-2 and 4-1BB receptors augments the antitumor activity of E7 DNA vaccines by increasing Ag-specific CTL responses

Human papillomavirus (HPV) infection is a major cause of cervical cancer. Here, we investigate whether concurrent therapy using HPV E7 DNA vaccines (pE7) plus IL-2 vs. IL-15 cDNA and anti-4-1BB Abs might augment antitumor activity against established tumors. IL-2 cDNA was slightly better than IL-15 cDNA as a pE7 adjuvant. Co-delivery of pE7+IL-2 cDNA increased tumor cure rates from 7% to 27%, whereas co-delivery of pE7+IL-2 cDNA with anti-4-1BB Abs increased tumor cure rates from 27% to 67% and elicited long-term memory responses. This increased activity was concomitant with increased induction of Ag-specific CTL activity and IFN-γ responses, but not with Ag-specific IgG production. Moreover, the combined stimulation of IL-2 and 4-1BB receptors with rIL-2 and anti-4-1BB Abs resulted in enhanced production of IFN-γ from Ag-specific CD8+ T cells. However, this effect was abolished by treatment with anti-IL-2 Abs and 4-1BB-Fc, suggesting that the observed effect was IL-2- and anti-4-1BB Ab-specific. A similar result was also obtained for Ag-specific CTL activity. Thus, these studies demonstrate that combined stimulation through the IL-2 and 4-1BB receptors augments the Ag-specific CD8+ CTL responses induced by pE7, increasing tumor cure rates and long-term antitumor immune memory. These findings may have implications for the design of DNA-based therapeutic vaccines against cancer.

Arecoline inhibits interleukin-2 secretion in Jurkat cells by decreasing the expression of alpha7-nicotinic acetylcholine receptors and prostaglandin E2

The purpose of the present study was to explore the effect of arecoline on phytohemagglutinin (PHA)-stimulated interleukin-2 (IL-2) secretion, the expression of alpha7-nicotinic acetylcholine receptors (α7-nAChRs), prostaglandin E2(PGE2) protein, and IL-2 mRNA in human lymphocyte cells (Jurkat cell line). The IL-2 and PGE2 were determined by enzyme-linked immunosorbent assay (ELISA). The expressions of phosphorylated extracellular signal-regulated kinase (ERK) and α7-nAChRs were determined by Western blotting. The level of IL-2 mRNA was determined by reverse-transcriptase polymerase chain reaction (RT-PCR). Arecoline, in a dose-dependent manner, significantly decreased IL-2 and PGE2 secretion by Jurkat cells incubated with 0 or 5 μg/ml 5 μg/ml PHA. PGE2 also significantly inhibited IL-2 secretion by Jurkat cells in a dose-dependent manner. In addition, reduced expression of PHA-induced ERK phosphorylation was observed in Jurkat cells treated with arecoline. PHA-enhanced IL-2 mRNA expression was also inhibited by arecoline. These results imply that arecoline inhibits the release of PGE2 and PHA-induced IL-2 secretion by Jurkat cells and that these effects seem to occur, at least in part, either through the attenuation of ERK in conjunction with a decrease of PHA-induced IL-2 mRNA expression. These results imply that arecoline inhibits the protein expression of α7-nAChRs , the release of PGE2 and PHA-induced IL-2 secretion by Jurkat cells.

Potent suppression of Kv1.3 potassium channel and IL-2 secretion by diphenyl phosphine oxide-1 in human T cells

Diphenyl phosphine oxide-1 (DPO-1) is a potent Kv1.5 channel inhibitor that has therapeutic potential for the treatment of atrial fibrillation. Many other Kv1.5 channel blockers also potently inhibit the Kv1.3 channel, but whether DPO-1 blocks Kv1.3 channels has not been investigated. The Kv1.3 channel is highly expressed in activated T cells, which is considered a favorable target for immunomodulation. Accordingly, we hypothesized that DPO-1 may exert immunosuppressive and anti-inflammatory effects by inhibiting Kv1.3 channel activity. In this study, DPO-1 blocked Kv1.3 current in a voltage-dependent and concentration-dependent manner, with IC₅₀ values of 2.58 µM in Jurkat cells and 3.11 µM in human peripheral blood T cells. DPO-1 also accelerated the inactivation rate and negatively shifted steady-state inactivation. Moreover, DPO-1 at 3 µM had no apparent effect on the Ca²⁺ activated potassium channel (K(Ca)) current in both Jurkat cells and human peripheral blood T cells. In Jurkat cells, pre-treatment with DPO-1 for 24 h decreased Kv1.3 current density, and protein expression by 48±6% and 60±9%, at 3 and 10 µM, respectively (both p<0.05). In addition, Ca²⁺ influx to Ca²⁺-depleted cells was blunted and IL-2 production was also reduced in activated Jurkat cells. IL-2 secretion was also inhibited by the Kv1.3 inhibitors margatoxin and charybdotoxin. Our results demonstrate for the first time that that DPO-1, at clinically relevant concentrations, blocks Kv1.3 channels, decreases Kv1.3 channel expression and suppresses IL-2 secretion. Therefore, DPO-1 may be a useful treatment strategy for immunologic disorders.

Pharmacologic inhibition of MALT1 protease by phenothiazines as a therapeutic approach for the treatment of aggressive ABC-DLBCL

Proteolytic activity of the mucosa-associated lymphoid tissue lymphoma translocation protein-1 (MALT1) paracaspase is required for survival of the activated B cell subtype of diffuse large B cell lymphoma (ABC-DLBCL). We have identified distinct derivatives of medicinal active phenothiazines, namely mepazine, thioridazine, and promazine, as small molecule inhibitors of the MALT1 protease. These phenothiazines selectively inhibit cleavage activity of recombinant and cellular MALT1 by a noncompetitive mechanism. Consequently, the compounds inhibit anti-apoptotic NF-κB signaling and elicit toxic effects selectively on MALT1-dependent ABC-DLBCL cells in vitro and in vivo. Our data provide a conceptual proof for a clinical application of distinct phenothiazines in the treatment of ABC-DLBCL.

Rhealba® oat plantlet extract: evidence of protein-free content and assessment of regulatory activity on immune inflammatory mediators

Owing to their high content of flavonoids and saponins, plantlets of Avena sativa L. (Poaceae) are likely to possess anti-inflammatory and immunoregulatory properties of value in the treatment of atopic dermatitis (AD). With a view to its potential use in atopic subjects at risk of developing sensitisation to dietary proteins, we prepared a plantlet extract without proteins and isolated 2 flavonoids, isoorientin-2''- O-arabinoside (1) and isovitexin-2''- O-arabinoside (2), and two saponins, avenacosides A (3) and B (4). The absence of protein in this extract was evidenced by electrophoresis and Western immunoblotting. Furthermore, Western immunoblotting demonstrated the absence of cross-reaction between grain and plantlet proteins. We evaluated the anti-inflammatory activity of the plantlet extract and its compounds IN VITRO in a model of keratinocyte inflammation: 6-keto prostaglandin F1 α production was inhibited by the plantlet extract (- 35 % and - 57 % at 10 and 30 µg/mL, respectively; p < 0.001) and isoorientin-2''- O-arabinoside (- 31 %, - 51 %, and - 56 % at 3, 10, and 30 µg/mL, respectively; p < 0.001). Intracellular interleukin-2 production in activated T lymphocytes was also inhibited by 16 %, 27 %, and 31 % with 3, 10, and 30 µg/mL plantlet extract, respectively, and by 23 % and 32 % with 3 and 10 µg/mL avenacoside A, respectively, (p < 0.001), demonstrating their immunoregulatory activity IN VITRO. The plantlet extract was also effective on the phenotype and function of dendritic cells (DC) differentiated from monocytes. It decreased the expression of major histocompatibility complex class II molecules on DC and significantly impaired their stimulatory activity on autologous T-cell proliferation (-25 %, p < 0.05). In conclusion, this protein-free oat plantlet extract exhibits anti-inflammatory and immunoregulatory activities in vitro.

Small-molecule inhibitors of IL-2/IL-2R: lessons learned and applied

The IL-2:IL-2R protein-protein interaction is of central importance to both healthy and diseased immune responses, and is one of the earliest examples of successful small-molecule inhibitor discovery against this target class. Drug-like inhibitors of IL-2 have been identified through a combination of fragment discovery, structure-based design, and medicinal chemistry; this discovery approach illustrates the importance of using a diverse range of complementary screening methods and analytical tools to achieve a comprehensive understanding of molecular recognition. The IL-2 story also provides insight into the dynamic nature of protein-protein interaction surfaces, their potential druggability, and the physical and chemical properties of effective small-molecule ligands. These lessons, from IL-2 and similar discovery programs, underscore an increasing awareness of the principles governing the development of drugs for protein-protein interactions.

Immunosuppressive activity on the murine immune responses of glycyrol from Glycyrrhiza uralensis via inhibition of calcineurin activity

CONTEXT

Calcineurin (CN), a unique protein phosphatase, plays an important role in immune regulation. Our laboratory has established an effective molecular drug-screening model based on CN activity.

OBJECTIVE

Our aim is to search for an effective immunosuppressant from Glycyrrhiza uralensis (Leguminosae).

MATERIALS AND METHODS

As guided by CN inhibitory test, an active compound was purified and identified as glycyrol. Immunosuppressive activity of glycyrol in vitro was assayed by T lymphocytes proliferation and mixed lymphocyte reaction (MLR). In addition, delayed-type hypersensitivity reaction (DTH) and skin allograft test in vivo were also carried out. Further, we have investigated the effect of glycyrol on phorbol 12-myristate 13-acetate (PMA)/ionomycin (Io)-stimulated IL-2 expression in Jurkat cells.

RESULTS

The enzymatic assay showed glycyrol (IC(50) = 84.6 μM) inhibited calcineurin activity in a dose-dependent manner. Glycyrol, at the non-cytotoxic concentration, significantly inhibited proliferation of murine spleen T lymphocytes induced by Concanavalin A (Con A) and mixed lymphocyte reaction (MLR) in vitro. In addition, mice treated with glycyrol had shown the dose-dependent decrease in delayed type hypersensitivity (DTH) and prolonged the graft survival by 59% compared to the control group (*p < 0.05). RT-PCR showed glycyrol suppressed IL-2 production in a concentration-dependent manner.

DISCUSSION AND CONCLUSION

Our results show the immunosuppressive activity of glycyrol and this activity should be due to its inhibitory effect on CN activity, thereby suppressing IL-2 production and regulating T lymphocytes. Thus, glycyrol could be a candidate for development as a novel immunomodulatory drug.

In CD28-costimulated human naïve CD4+ T cells, I-κB kinase controls the expression of cell cycle regulatory proteins via interleukin-2-independent mechanisms

Stimulation of naïve CD4(+) T cells through engagement of the T-cell receptor (TCR) and the CD28 co-receptor initiates cell proliferation which critically depends on interleukin (IL)-2 secretion and subsequent autocrine signalling via the IL-2 receptor. However, several studies indicate that in CD28-costimulated T cells additional IL-2-independent signals are also required for cell proliferation. In this study, using a neutralizing anti-human IL-2 antibody and two selective, structurally unrelated, cell-permeable I-κB kinase (IKK) inhibitors, BMS-345541 and PS-1145, we show that in human naïve CD4(+) T cells stimulated through a short engagement of the TCR and the CD28 co-receptor, IKK controls the expression of the cell cycle regulatory proteins cyclin D3, cyclin E and cyclin-dependent kinase 2 (CDK2) and the stability of the F-box protein S-phase kinase-associated protein 2 (SKP2) and its co-factor CDC28 protein kinase regulatory subunit 1B (CKS1B), through IL-2-independent mechanisms.

Identification of the functional domain of duck interleukin 2 binding to duck interleukin 2 receptor alpha chain

Interleukin 2 (IL-2) plays an important role in the growth and differentiation of lymphocytes. To identify the functional domains of duck IL-2 (duIL-2), 4 neutralizing monoclonal antibodies (mAbs) to duIL-2 were used to finely map the functional domains of the duIL-2 protein. The mimotopes of 4 anti-duIL-2 mAbs, including LVXGSMPS, KPHKHHXHHSHM, WXXXKAKP, and HVPNERYPLR, were identified by phage display and peptide-competitive ELISA. These mimotopes constitute an important functional domain, Y(32) approximately T(44) (domain I), in the duIL-2 molecule. The bioactivity of the domain I peptide on in vitro lymphocyte proliferation was inhibited by duIL-2Ralpha. A tertiary structure model of duIL-2 showed that domain I is positioned in the long A-B loop and the N-terminal of Helix B. These data provided experimental evidence for elucidating the interaction between duIL-2 and duIL-2Ralpha.

Evaluation of metered dose inhaler (MDI) formulations of ciclosporin

Our purpose was to evaluate metered dose inhaler (MDI) formulations of ciclosporin (cyclosporine) for aerodynamic properties, chemical stability and bioactivity. Ciclosporin formulations (0.1, 0.5 and 1.0% w/w) were prepared in hydrofluoroalkane (HFA) propellants (134a and 227) containing 3 and 6% ethanol. Aerodynamic properties of the MDI formulations were analysed using an eight-stage Andersen cascade impactor and respirable mass and non-respirable mass, mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were determined from the impaction profiles. The chemical stability of 0.1% ciclosporin in HFA 227 containing 3% ethanol formulation stored at room temperature and 40°C was evaluated by HPLC at 0, 14, 30 and 90 days. The bioactivity of ciclosporin MDI formulations was evaluated by determining the ciclosporin-mediated inhibition of interleukin-2 (IL-2) release from human Jurkat cells stimulated with phorbol 12-myristate 13-acetate (PMA). As ethanol concentration increased from 3 to 6%, respirable mass decreased from 2.3 mg per five actuations to 0.04 mg per five actuations for HFA 227 formulations, and from 1.5 mg to 0.09 mg per five actuations for HFA 134a formulations. The MMAD for both HFA 134a and 227 formulations increased with an increase in ciclosporin concentration. HPLC analysis showed ciclosporin to be extremely stable in HFA 227 at room temperature and 40°C. Stimulation of Jurkat cells with PMA released significant amounts of IL-2, which was inhibited by ciclosporin in a dose-dependent manner. This study shows the feasibility of developing chemically stable and bioactive HFA-based MDI formulations of ciclosporin.

2-Benzimidazolyl-9-(chroman-4-yl)-purinone derivatives as JAK3 inhibitors

A novel class of Janus tyrosine kinase 3 (JAK3) inhibitors based on a 2-benzimidazoylpurinone core structure is described. Through substitution of the benzimidazoyl moiety and optimization of the N-9 substituent of the purinone, compound 24 was identified incorporating a chroman-based functional group. Compound 24 shows excellent kinase activity, good oral bioavailability and demonstrates efficacy in an acute mechanistic mouse model through inhibition of interleukin-2 (IL-2) induced interferon-gamma (INF-gamma) production.

Blockade of hyaluronan inhibits IL-2-induced vascular leak syndrome and maintains effectiveness of IL-2 treatment for metastatic melanoma

Vascular leak syndrome (VLS) is a life-threatening toxicity induced during IL-2 treatment of cancer patients. The mechanism of IL-2-induced VLS is still poorly understood. At present, there is no specific therapy for VLS. Previous studies from our laboratory demonstrated that hyaluronan (HA), a large glycosaminoglycan, abundant in the extracellular matrix and on the cell surface, caused a marked increase of IL-2-induced VLS in the lungs and liver of C57BL/6 mice. Conversely, blockade or knockout of its major receptor, CD44, resulted in a marked decrease of VLS, thereby suggesting a role for HA in VLS. In this study, we report a novel means to prevent IL-2-induced VLS by blocking endogenous HA with HA-specific binding peptide, Pep-1, a newly isolated peptide which specifically binds to soluble, cell-associated, and immobilized forms of HA. Our results demonstrated that blocking HA with Pep-1 dramatically inhibited IL-2-induced VLS in both normal mice as well as in mice bearing melanoma. Moreover, Pep-1 treatment maintained the effectiveness of IL-2 and prevented the metastasis of melanoma. IL-2-induced emigration of lymphocytes across the endothelium and cytotoxicity against tumor by lymphokine-activated killer cells were not affected by Pep-1. Instead, use of Pep-1 maintained endothelial integrity and reduced their apoptosis during IL-2-induced VLS. These data suggested that HA plays a critical role in regulating endothelial cell damage and induction of IL-2-mediated VLS. Also, blockade of HA using Pep-1 could constitute a novel therapeutic modality to prevent IL-2-mediated toxicity, thereby facilitating the effectiveness of high-dose IL-2 in the treatment of metastatic melanomas.

Conjugated linoleic acid supplementation reduces peripheral blood mononuclear cell interleukin-2 production in healthy middle-aged males

Conjugated linoleic acid (CLA) refers to geometric and positional isomers of linoleic acid. Animal studies have shown that CLA modulates the immune system and suggest that it may have a therapeutic role in inflammatory disorders. This double-blind placebo-controlled intervention trial investigated the effects of CLA supplementation on indices of immunity relating to cardiovascular disease (CVD) in a cohort of healthy middle-aged male volunteers. Subjects were randomly assigned to supplement their diet with 2.2 g 50:50 isomeric blend of cis 9, trans 11 (c9, t11)-CLA and trans 10, cis 12 (t10, c12)-CLA or placebo daily for 8 weeks. Interleukin (IL) 2, IL-10 and tumour necrosis factor (TNF) alpha were measured in the supernatant of cultured unstimulated and concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMC) by ELISA. Serum IL-6 and plasma CRP were measured by ELISA and plasma fibrinogen by automated clotting assay. Gene expression was investigated by real-time RT-PCR. CLA supplementation significantly reduced Con A-stimulated PBMC IL-2 secretion (37.1%; P=.02). CLA supplementation had no significant effect on transcription of IL-2. CLA supplementation had no direct significant effects on PBMC TNFalpha or IL-10 secretion. Other inflammatory markers associated with CVD, including IL-6, CRP and fibrinogen, were not affected by CLA supplementation. This study showed that CLA supplementation reduced PBMC IL-2 secretion from Con A-stimulated PBMC but lacked effect on other markers of the human inflammatory response.

Cutting edge: opposite effects of IL-1 and IL-2 on the regulation of IL-17+ T cell pool IL-1 subverts IL-2-mediated suppression

In this report, we show that IL-17(+)CD4(+) and IL-17(+)CD8(+) T cells are largely found in lung and digestive mucosa compartments in normal mice. Endogenous and exogenous IL-1 dramatically contribute to IL-17(+) T cell differentiation mediated by TGFbeta and IL-6. IL-1 is capable of stimulating IL-17(+) T cell differentiation in the absence of IL-6. Furthermore, although IL-2 reduces IL-17(+) T cell differentiation, IL-1 completely disables this effect. Mechanistically, IL-1 and IL-2 play opposite roles in regulating the expression of several molecules regulating Th17 cell differentiation, including the orphan nuclear receptor ROR gamma t, the IL-1 receptor, and the IL-23 receptor. IL-1 subverts the effects of IL-2 on the expression of these gene transcripts. Altogether, our work demonstrates that IL-6 is important but not indispensable for IL-17(+) T cell differentiation and that IL-1 plays a predominant role in promoting IL-17(+) T cell induction. Thus, the IL-17(+) T cell pool may be controlled by the local cytokine profile in the microenvironment.

Suppression of interleukin-2 gene expression by isoeugenol is mediated through down-regulation of NF-AT and NF-κB

Isoeugenol is a naturally occurring methoxyphenol found in a variety of foods and essential oils. We investigated the effect of isoeugenol on T-cell function and the regulatory mechanism underlying its effect. Isoeugenol and its structural analog eugenol suppressed the lymphoproliferative response to concanavalin A stimulation in B6C3F1 mouse splenocyte cultures. Isoeugenol inhibited phorbol 12-myristate 13-acetate (PMA) plus ionomycin (Io)-induced IL-2 mRNA expression and protein secretion in B6C3F1 mouse splenocytes, and in EL4.IL-2 mouse T-cells, as determined by real-time RT-PCR and ELISA, respectively. To further characterize the inhibitory mechanism of isoeugenol at the transcriptional level, we examined the DNA binding activity of the transcription factors for IL-2 using an electrophoretic mobility shift assay. Isoeugenol decreased the binding activity of NF-AT and NF-kappaB in PMA/Io-stimulated EL4.IL-2 cells, but no significant effect was observed for AP-1 or Oct binding activity. Western blot analysis showed that isoeugenol also decreased the nuclear translocation of cytoplasmic NF-AT and NF-kappaB. These results suggest that isoeugenol suppresses IL-2 production through a decrease of IL-2 mRNA expression and that the inhibition is mediated, at least in part, through the down-regulation of NF-AT and NF-kappaB.

[Analgesic effect of interleukin-2 in mouse models of spared nerve injury]

OBJECTIVE

To investigate the analgesic effect of interleukin-2 (IL-2) in mice with spared nerve injury (SNI).

METHOD

IL-2 was intraperitoneally injected in mice with induced SNI, and von Frey Filaments test and cold plate test were carried out to accesses the analgesic effects of IL-2 and the effect of naloxone in antagonizing the effects of IL-2.

RESULTS

IL-2 produced analgesic effects against hyperalgesia and allodynia in mouse models of SNI, and the effect of IL-2 lasted for more than 24 h, showing a double-peak pattern in its action with the two peaks occurring at 30 and 105 min, respectively. The effect of IL-2 could be significantly antagonized by naloxone.

CONCLUSIONS

IL-2 has long-lasting analgesic effects in mouse models of SNI model, showing a double-peak pattern of its action. The analgesic effect of IL-2 is probably mediated by opiate receptor.

Naive CD8+ T cells differentiate into protective memory-like cells after IL-2 anti IL-2 complex treatment in vivo

An optimal CD8⁺ T cell response requires signals from the T cell receptor (TCR), co-stimulatory molecules, and cytokines. In most cases, the relative contribution of these signals to CD8⁺ T cell proliferation, accumulation, effector function, and differentiation to memory is unknown. Recent work (Boyman, O., M. Kovar, M.P. Rubinstein, C.D. Surh, and J. Sprent. 2006. Science. 311:1924–1927; Kamimura, D., Y. Sawa, M. Sato, E. Agung, T. Hirano, and M. Murakami. 2006. J. Immunol. 177:306–314) has shown that anti–interleukin (IL) 2 monoclonal antibodies that are neutralizing in vitro enhance the potency of IL-2 in vivo. We investigated the role of IL-2 signals in driving CD8⁺ T cell proliferation in the absence of TCR stimulation by foreign antigen. IL-2 signals induced rapid activation of signal transducer and activator of transcription 5 in all CD8⁺ T cells, both naive and memory phenotype, and promoted the differentiation of naive CD8⁺ T cells into effector cells. IL-2–anti–IL-2 complexes induced proliferation of naive CD8⁺ T cells in an environment with limited access to self–major histocompatibility complex (MHC) and when competition for self-MHC ligands was severe. After transfer into wild-type animals, IL-2–activated CD8⁺ T cells attained and maintained a central memory phenotype and protected against lethal bacterial infection. IL-2–anti–IL-2 complex–driven memory-like CD8⁺ T cells had incomplete cellular fitness compared with antigen-driven memory cells regarding homeostatic turnover and cytokine production. These results suggest that intense IL-2 signals, with limited contribution from the TCR, program the differentiation of protective memory-like CD8⁺ cells but are insufficient to guarantee overall cellular fitness.

Paradoxical effect of reduced costimulation in T cell-mediated colitis

B7-1 and B7-2 play different roles in the pathogenesis of autoimmunity, but this is controversial. We analyzed colitis induced by transfer of CD45RB(high)CD4(+) T cells to RAG(-/-) recipients lacking B7-1 and/or B7-2. Surprisingly, disease was greatly accelerated in RAG(-/-) recipients deficient for either B7-1 or B7-2, especially in the B7-2(-/-) recipients. This accelerated colitis induction correlated with increased T cell division in vivo and production of Th1 cytokines. Although colitis pathogenesis following T cell transfer was inhibited in the absence of CD40L expression, CD40-CD40L interactions were not required in the B7-2(-/-) RAG(-/-) recipients. In vitro priming by APCs lacking either B7-1 or B7-2 caused decreased IL-2 production, which led to decreased CTLA-4 expression, although T cells primed in this way could respond vigorously upon restimulation by producing increased IL-2 and proinflammatory cytokines. Consistent with this mechanism, we demonstrate that blocking IL-2 early after T cell transfer accelerated colitis. Our data therefore outline a mechanism whereby synergistic costimulation by B7-1 and B7-2 molecules during priming is required for optimal IL-2 production. The consequent inhibitory effect of full CTLA-4 expression, induced by IL-2, may slow colitis, even in the absence of regulatory T cells.

ICER/CREM-mediated transcriptional attenuation of IL-2 and its role in suppression by regulatory T cells

Here, we report that inducible cAMP early repressor/cAMP response element modulator (ICER/CREM) is induced early in CD25(+)CD4(+) regulatory T cell (T(R)) assays mainly in activated Foxp3(-) effector T cells and this induction correlates with sharp decrease in number of IL-2-expressing T cells. Importantly, RNAi targeting of ICER/CREM in responder CD25(-)CD4(+) T cells antagonizes T(R)-mediated suppression. Moreover, forced expression of Foxp3 in naive CD25(-) T cells induces constitutive expression of ICER/CREM in T cells with a regulatory phenotype. Foxp3 facilitates expression of ICER/CREM both in Foxp3 transductants as well as CD25(-) responder T cells suggesting that induction of T(R) function in suppression assays may utilize contact-dependent interaction. Indeed, CTLA-4 blockade or use of B7-deficient CD25(-) responder T cells prevents ICER/CREM accumulation and leads to the rescue of IL-2 expression. Therefore, we propose that CTLA-4 binding to B7 ligands expressed on activated ligand-bearing Foxp3(-) effector T cells results in ICER/CREM-mediated transcriptional attenuation of IL-2. Collectively, these data suggest that Foxp3 expression in T(R) cells imposes suppression in contact-dependent fashion by induction of constitutive ICER/CREM expression in activated CD25(+) Foxp3(-) T cell effectors thus preventing them from producing IL-2.

T cells contribute to lysophosphatidylcholine-induced macrophage activation and demyelination in the CNS

We have previously shown that intraspinal microinjection of lysophosphatidylcholine (LPC), a potent demyelinating agent, results in a rapid but brief influx of T cells (between 6 and 12 h). This is accompanied by a robust activation of macrophages/microglia that leads to demyelination by 48 h. In the present study, we examined whether this brief influx of T cells contributes to the activation of macrophages/microglia and demyelination by injecting LPC into the dorsal column white matter of athymic Nude mice that lack T cells. We show that there is a significant reduction in macrophage/microglial activation and myelin clearance after LPC injection in Nude mice as compared with wildtype controls. We also show that there is no difference in the recruitment of hematogenous macrophages into the spinal cord after LPC injection in the two mouse strains. Of the T cell cytokines assessed, there was a marked reduction in the mRNA expression of interleukin-2 (IL-2) in Nude mice compared with wildtype animals. Neutralizing IL-2 with function-blocking antibodies in wildtype animals resulted in a significant decrease in the number of phagocytic macrophages/microglia and a reduction in demyelination induced by LPC. While there may be other defects in Nude mice that might contribute to the effects shown here, these data suggest that the brief influx of T cells in this model of chemically-induced demyelination could play a role in macrophage/microglial activation and demyelination. These results may also have implications for remyelination in this and other types of CNS damage.

Cytokine-dependent Blimp-1 expression in activated T cells inhibits IL-2 production

After Ag activation of naive T cells in vitro, extensive growth and differentiation into effector cells depend upon IL-2. DNA microarray analysis was used to identify IL-2-dependent molecules regulating this process. In this study, we show that the transcriptional repressor B lymphocyte-induced maturation protein 1 (Blimp-1) is expressed by a cytokine-dependent pathway in activated T lymphocytes. IL-2 production by activated CD4(+) and CD8(+) T cells inversely correlated with Blimp-1 levels as higher IL-2 production was associated with lower Blimp-1 expression. Furthermore, ectopic expression of Blimp-1 by activated T cells inhibited IL-2 production but enhanced granzyme B and CD25 expression. Collectively, these findings indicate that there is a negative feedback regulatory loop in activated T cells such that IL-2 inhibits its own production through induction of Blimp-1 while promoting an effector cell phenotype.

A humanized monoclonal antibody against interleukin-2 that can inactivate the cytokine/receptor complex

Inhibition of the interleukin-2 (IL-2) pathway has potent immunosuppressive activity in humans as is evident from the broad therapeutic utility of cyclosporine, rapamycin, tacrolimus, and monoclonal antibodies blocking the high-affinity subunit of the IL-2 receptor (CD25). Here we describe a humanized antibody, MT204, interfering with IL-2 signaling by a novel mechanism. Although MT204 did not prevent IL-2 from binding to CD25, it potently antagonized downstream signaling events of IL-2 at sub-nanomolar concentrations, such as STAT3 tyrosine phosphorylation, expression of CD124, production of gamma-interferon and cell proliferation. While MT204 and the anti-CD25 mAb daclizumab were equally effective in inhibiting autocrine growth of human CD4(+) T cells, MT204 was far superior in preventing proliferation of NKL lymphoma cells, production of gamma-interferon by natural killer (NK) cells and proliferation of primary NK cells. MT204 has potential as a novel immunosuppressive and anti-proliferative therapy with an apparently broader spectrum of activities than anti-CD25 antibodies.

A limited course of soluble CD83 delays acute cellular rejection of MHC-mismatched mouse skin allografts

CD83 is a surface marker expressed on matured dendritic cells (DCs). It plays a pivotal role in the mediation of DC/T cell interaction and induction of T-cell activation. Previous studies have suggested that a soluble form of CD83 could suppress DC maturation and inhibit T-cell activation and, as a result, it can prevent paralysis associated with experimental autoimmune encephalomyelitis. Here, we explored its potential effect on allograft rejection in a fully major histocompatibility complex-mismatched murine skin transplantation model. A form of mouse soluble CD83 (CD83-Ig) fused the extracellular domain of murine CD83 with human IgG1alpha Fc tail was purified from transfected COS-7 cell. It was found that the treatment of recipient mice with CD83-Ig significantly delayed allograft rejection. Especially, when T cells originated from recipients treated with CD83-Ig re-stimulated with donor-specific splenocytes, they showed a significant reduced responding capability as compared with that of originated from control recipients. In line with these results, a reduction for serum IFN-gamma and IL-2 and a decreased mRNA expression of IFN-gamma and IL-2 in allograft infiltrated immune cells were also observed. Our results suggest that CD83-Ig could be useful for the treatment of allograft rejection in combination with other therapeutic strategies.

Areca nut extract suppresses T-cell activation and interferon-gamma production via the induction of oxidative stress

Areca quid chewing is a major risk factor associated with oral submucous fibrosis (OSF) and oral cancer. Experimental evidence indicates that immune deterioration is associated with the pathophysiology of OSF and oral cancer. In addition, reactive oxygen species (ROS) is shown to play a role in the cytotoxic and genotoxic effect induced by areca nut extracts (ANE) in oral cells. The present studies investigated the effects of ANE on T-cell reactivity and the role of ROS in ANE effects. Treatment of splenocytes with ANE induced a marked cytotoxic effect, and suppressed the production of IL-2 and IFN-gamma, whereas the production of IL-4 was unaffected. The ANE-mediated cytotoxicity, and suppression of IFN-gamma and IL-2 production were attenuated by the presence of antioxidant N-acetyl-l-cysteine (NAC). Moreover, flow cytometric analysis demonstrated an increase in cellular ROS levels in splenic T-cells treated with ANE, which was also attenuated by the presence of NAC. Concordantly, the cellular level of glutathione was diminished by ANE in splenic T-cells pretreated with NAC. Collectively, these results demonstrated that ANE markedly suppressed T-cell activation and Th1 cytokine production, which was mediated, at least in part, by the induction of oxidative stress.

(S)-Armepavine inhibits human peripheral blood mononuclear cell activation by regulating Itk and PLCγ activation in a PI-3K-dependent manner

Chinese herbs are useful edible and medicinal plants for their immune modulatory functions. We have proven that (S)-armepavine (C19H23O3N; MW313) from Nelumbo nucifera inhibits the proliferation of human PBMCs activated with PHA and improves autoimmune diseases in MRL/MpJ-lpr/lpr mice. In the present study, the pharmacological activities of (S)-armepavine were evaluated in PHA-activated PBMCs. The results showed that (S)-armepavine suppressed PHA-induced PBMC proliferation and genes expression of IL-2 and IFN-gamma without direct cytotoxicity. Inhibition of NF-AT and NF-kappaB activation suggested phospholipase Cgamma (PLCgamma)-mediated Ca2+ mobilization and protein kinase C activation were blocked by (S)-armepavine. Phosphorylation of PLCgamma is regulated by lymphocyte-specific kinase (Lck), ZAP-70, and IL-2-inducible T cell kinase (Itk). We found (S)-armepavine inhibited PHA-induced phosphorylation of Itk and PLCgamma efficiently but did not influence Lck or ZAP-70 phosphorylation. In addition, ZAP-70-mediated pathways, such as the association of linker for activation of T cells with PLCgamma and activation of ERK, were also intact in the presence of (S)-armepavine. Finally, reduction of phosphoinositide 3,4,5-trisphosphate formation and Akt phosphorylation suggested that (S)-armepavine inhibited Itk, and PLCgamma phosphorylation might be a result of the influence of PI-3K activation. Addition of exogenous IL-2 or PMA/A23187 rescued PBMC proliferation in the presence of (S)-armepavine. Therefore, we concluded that (S)-armepavine inhibited PHA-induced cell proliferation and cytokine production in a major way by blocking membrane-proximal effectors such as Itk and PLCgamma in a PI-3K-dependent manner.

2-aminothiazole as a novel kinase inhibitor template. Structure-activity relationship studies toward the discovery of N-(2-chloro-6-methylphenyl)-2-[[6-[4-(2-hydroxyethyl)-1- piperazinyl)]-2-methyl-4-pyrimidinyl]amino)]-1,3-thiazole-5-carboxamide (dasatinib, BMS-354825) as a potent pan-Src kinase inhibitor

2-aminothiazole (1) was discovered as a novel Src family kinase inhibitor template through screening of our internal compound collection. Optimization through successive structure-activity relationship iterations identified analogs 2 (Dasatinib, BMS-354825) and 12m as pan-Src inhibitors with nanomolar to subnanomolar potencies in biochemical and cellular assays. Molecular modeling was used to construct a putative binding model for Lck inhibition by this class of compounds. The framework of key hydrogen-bond interactions proposed by this model was in agreement with the subsequent, published crystal structure of 2 bound to structurally similar Abl kinase. The oral efficacy of this class of inhibitors was demonstrated with 12m in inhibiting the proinflammatory cytokine IL-2 ex vivo in mice (ED50 approximately 5 mg/kg) and in reducing TNF levels in an acute murine model of inflammation (90% inhibition in LPS-induced TNFalpha production when dosed orally at 60 mg/kg, 2 h prior to LPS administration). The oral efficacy of 12m was further demonstrated in a chronic model of adjuvant arthritis in rats with established disease when administered orally at 0.3 and 3 mg/kg twice daily. Dasatinib (2) is currently in clinical trials for the treatment of chronic myelogenous leukemia.

Anti-Tac (daclizumab, Zenapax) in the treatment of leukemia, autoimmune diseases, and in the prevention of allograft rejection: a 25-year personal odyssey

Twenty-five years ago, we reported the production of the monoclonal antibody, anti-Tac that identifies the IL-2 receptor alpha subunit and blocks the interaction of IL-2 with this growth factor receptor. In 1997, daclizumab (Zenapax), the humanized form of this antibody, was approved by the FDA for use in the prevention of renal allograft rejection. In addition, we demonstrated that daclizumab is of value in the treatment of patients with noninfectious uveitis, multiple sclerosis, and the neurological disease human T-cell lymphotropic virus I associated myelopathy/tropical spastic paraparesis (HAM/TSP). Others demonstrated therapeutic efficacy with daclizumab in patients with pure red cell aplasia, aplastic anemia, and psoriasis. Thus, translation of basic insights concerning the IL-2/IL-2 receptor system obtained using the monoclonal antibody daclizumab provided a useful strategy for the prevention of organ allograft rejection and the treatment of patients with select autoimmune diseases or T-cell leukemia/lymphoma.

Inhibitory effect of pasireotide and octreotide on lymphocyte activation

Somatostatin (SST) regulates the function of the central and peripheral nervous system, the endocrine and exocrine organs, as well as the vascular and immune system. These actions are mediated by five specific membrane somatostatin receptors. This study compares the effects on human lymphocytes of two long-acting somatostatin analogues that have different receptor affinity: octreotide and pasireotide. Both analogues have an antiproliferative effect on human lymphocyte proliferation, but they act at different concentration and, while octreotide enhances IL10 and inhibits gamma IFN pasireotide inhibits IL2 and gamma IFN. In both sets of experiment the different behaviour of the two analogues could be due to their different affinity to the SSTR subtypes. Finally this study suggest that the growth inhibitory action of somatostatin analogues is an apoptotic phenomenon and it can be mediated by SSTR2a, in the case of octreotide, and by SSTR3 when pasireotide is used or it can be mediated by the heterodimerization of the two receptor.

Inhibition of inducible tumor necrosis factor-α expression by the fungal epipolythiodiketopiperazine gliovirin

TNF-alpha is a major pro-inflammatory cytokine that regulates further cytokine induction, especially of IL-1 and IL-6, in many human diseases including cancer, inflammation and immune disorders. In a search for new inhibitors of inducible TNF-alpha promoter activity and expression, cultures of the imperfect fungus Trichoderma harzianum were found to produce gliovirin, a previously isolated epipolythiodiketopiperazine. Gliovirin inhibited inducible TNF-alpha promoter activity and synthesis in LPS/IFN-gamma-stimulated macrophages/monocytes and Jurkat T-cells, co-stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA)/ionomycin, in a dose-dependent manner, with IC(50) values ranging from 0.21 to 2.1 microM (0.1-1 microg/ml). Studies on the mode of action revealed that gliovirin suppresses TNF-alpha synthesis by inhibiting the activation of extracellular signal-regulated kinase (ERK), thereby blocking the pathway leading to activation of the transcription factors AP-1 and NF-kappaB, the latter of which is involved in the inducible expression of many pro-inflammatory genes. Gliovirin also significantly reduced TPA/ionomycin-induced IL-2 mRNA levels and synthesis in Jurkat cells at low micromolar concentrations.

Overexpression of A3 adenosine receptor in peripheral blood mononuclear cells in rheumatoid arthritis: involvement of nuclear factor-kappaB in mediating receptor level

OBJECTIVE

A3 adenosine receptor (A3AR) upregulation has been found in cells of synovial tissue and in peripheral blood mononuclear cells (PBMC) of rats with adjuvant-induced arthritis. We investigated A3AR levels in PBMC of patients with rheumatoid arthritis (RA) and in mitogen-activated PBMC from healthy subjects. We examined the role of nuclear factor-kappaB (NF-kappaB), a transcription factor present in the A3AR promoter, in mediating receptor upregulation.

METHODS

A3AR and NF-kappaB protein levels were evaluated in PBMC of RA patients (n = 23) and healthy subjects by Western blot. A3AR and NF-kappaB levels were also analyzed in phytohemagglutinin (PHA) and lipopolysaccharide (LPS)-stimulated PBMC in the presence and absence of antibodies against interleukin 2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha). Reverse transcription-polymerase chain reaction was performed in PHA-stimulated PBMC of healthy subjects to determine A3AR expression.

RESULTS

A3AR was overexpressed in PBMC of RA patients compared to healthy subjects and was directly correlated to an increase in NF-kappaB. Similar findings were observed in PHA and LPS-stimulated PBMC from healthy subjects. Antibodies against IL-2 or TNF-alpha prevented the increase in A3AR and NF-kappaB expression.

CONCLUSION

Overexpression of A3AR was found in PBMC of RA patients. Receptor upregulation was induced by inflammatory cytokines controlling the expression of the A3AR transcription factor NF-kappaB.

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.

Discrepancy in CD3-Transmembrane Peptide Activity between In Vitro and In Vivo T-Cell Inhibition

Electrostatic amino acid interactions between receptor subunits within the T-cell antigen receptor (TCR) transmembrane domain are critical for the formation of the TCR-CD3 complex. Core peptide, a short peptide corresponding to the TCR-alpha transmembrane region, containing two positively charged amino acids, is known to inhibit T-cell function in vitro and in vivo. The aim of this study was to examine peptides corresponding to the syntactic transmembrane CD3 region binding to TCR-alpha for their ability to inhibit T-cell activation in vitro and in vivo. Three peptides matching the transmembrane sequence of CD3-delta, -epsilon and -gamma were synthesized and tested in different biological in vitro and in vivo systems for their effect on T-cell activity. The CD3-peptides had no impact on T-cell function in vitro, but surprisingly, decreased signs of inflammation in the adjuvant arthritis rat model in vivo. Preliminary evidence suggests that peptides with CD3 transmembrane-derived sequences can inhibit an immune response as assessed by adjuvant-induced arthritis. The lack of in vitro activity may lead to a wasteful disregard of active compounds in the process of drug discovery and development.

Defective activation of protein kinase C and Ras-ERK pathways limits IL-2 production and proliferation by CD4+CD25+ regulatory T cells

Naturally occurring CD4+CD25+ regulatory T cells (Tregs), which play an important role in the maintenance of self-tolerance, proliferate poorly and fail to produce IL-2 following stimulation in vitro with peptide-pulsed or anti-CD3-treated APCs. When TCR proximal and distal signaling events were examined in Tregs, we observed impairments in the amplitude and duration of tyrosine phosphorylation when compared with the response of CD4+CD25- T cells. Defects were also seen in the activity of phospholipase C-gamma and in signals downstream of this enzyme including calcium mobilization, NFAT, NF-kappaB, and Ras-ERK-AP-1 activation. Enhanced stimulation of diacylglycerol-dependent pathways by inhibition of diacylglycerol metabolism could overcome the "anergic state" and support the ability of Tregs to up-regulate CD69, produce IL-2, and proliferate. Our results demonstrate that Tregs maintain their hyporesponsive state by suppressing the induction and propagation of TCR-initiated signals to control the accumulation of second messengers necessary for IL-2 production and proliferation.

Monoclonal anti-double-stranded DNA antibodies cross-react with phosphoglycerate kinase 1 and inhibit the expression and production of IL-2 in activated Jurkat T cell line

Anti-double strand DNA antibodies (anti-dsDNA) involve in lupus nephritis. However, their role in tissue damage mechanism remains unclear. In this study, a 45-kDa cognate antigen of anti-dsDNA monoclonal antibodies 9D7 was identified by two-dimensional gel electrophoresis and determined to be human phosphoglycerate kinase 1 (PGK-1) by MALDI-TOF analysis. The binding of 9D7 to PGK-1 was not affected by DNase I but was inhibited by thymus dsDNA. Human SLE sera with high anti-dsDNA titers had a high affinity with PGK. In activated Jurkat T cells, 9D7 decreased the PGK-1 mRNA production and IL-2 promoter activity. Reduction in IL-2 gene expression and protein production were observed in the 9D7-treated cells. Because PGK-1 deficiency may cause mental tardy and hemolytic anemia, interaction between anti-dsDNA and PGK-1 may be important in lupus pathogenesis. Moreover, reduction in IL-2 production by anti-dsDNA suggests their role in increasing infection rate and decreasing proper generation of activation-induced cell death.

PD-L2:PD-1 involvement in T cell proliferation, cytokine production, and integrin-mediated adhesion

The B7 family member programmed death ligand 2 (PD-L2) has been implicated in both positive and negative regulation of T cell activity. In this study, we demonstrate that on human T cells, PD-L2 acts only as a negative regulator of T cell activity, inhibiting proliferation, IL-2 production, and IFN-gamma production via its interaction with programmed death-1 (PD-1). This study also shows a novel role for PD-1 in inhibiting beta1 and beta2 integrin-mediated adhesion. PD-L2 inhibition of T cell function involves modulation of the phosphoinositide 3-OH kinase (PI 3-K)/AKT and extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) pathways, with PD-L2 inhibiting anti-CD3-induced AKT phosphorylation within minutes and ERK phosphorylation after hours. Analysis of phosphatase activity of Src homology 2 domain-containing tyrosine phosphatase (SHP)-1 and SHP-2 in response to anti-CD3 mAb or anti-CD3 mAb + PD-L2 stimulation revealed that while SHP-1 phosphatase activity is not affected by stimulation, SHP-2 phosphatase activity is significantly increased by anti-CD3 mAb + PD-L2 stimulation. Anti-CD3 mAb + PD-L2 stimulation also increased the level of SHP-2 associated with the PD-1 receptor. These results suggest that catalytically active SHP-2 associated with the PD-1 receptor is involved in modulating T cell function.

Dual effects of Sprouty1 on TCR signaling depending on the differentiation state of the T cell

Sprouty (Spry) is known to be a negative feedback inhibitor of growth factor receptor signaling through inhibition of the Ras/MAPK pathway. Several groups, however, have reported a positive role for Spry involving sequestration of the inhibitory protein c-Cbl. Thus, Spry may have various functions in the regulation of receptor-mediated signaling depending on the context. In the immune system, the function of Spry is unknown. In this study, we investigated the role of Spry1 in T cell activation. Spry1, among the four mammalian homologs, was specifically induced by TCR signaling of CD4(+) murine T cells. In fully differentiated Th1 clones, overexpressed Spry1 inhibited TCR signaling and decreased IL-2 production while reducing expression with specific siRNA transfection had the opposite effect, increasing IL-2 production. In contrast, in naive T cells, Spry1 overexpression enhanced TCR signaling, and increased proliferation and IL-2 production, while siRNA transfection again had the opposite effect, reducing IL-2 production following activation. The enhancing effect in naive cells was abrogated by preactivation of the T cells with Ag and APC, indicating that the history of exposure to Ag is correlated with a hierarchy of T cell responsiveness to Spry1. Furthermore, both the NF-AT and MAPK pathways were influenced by Spry1, implying a different molecular mechanism from that for growth factor receptor signaling. Thus, Spry1 uses a novel mechanism to bring about differential effects on TCR signaling through the same receptor, depending on the differentiation state of the T cell.

Adiponectin is a negative regulator of NK cell cytotoxicity

NK cells are a key component of innate immune systems, and their activity is regulated by cytokines and hormones. Adiponectin, which is secreted from white adipose tissues, plays important roles in various diseases, including hypertension, cardiovascular diseases, inflammatory disorders, and cancer. In this study the effect of adiponectin on NK cell activity was investigated. Adiponectin was found to suppress the IL-2-enhanced cytotoxic activity of NK cells without affecting basal NK cell cytotoxicity and to inhibit IL-2-induced NF-kappaB activation via activation of the AMP-activated protein kinase, indicating that it suppresses IL-2-enhanced NK cell cytotoxicity through the AMP-activated protein kinase-mediated inhibition of NF-kappaB activation. IFN-gamma enhances NK cell cytotoxicity by causing an increase in the levels of expression of TRAIL and Fas ligand. The production of IFN-gamma, one of the NF-kappaB target genes in NK cells, was also found to be suppressed by adiponectin, accompanied by the subsequent down-regulation of IFN-gamma-inducible TRAIL and Fas ligand expression. These results clearly demonstrate that adiponectin is a potent negative regulator of IL-2-induced NK cell activation and thus may act as an in vivo regulator of anti-inflammatory functions.

Suppression of T lymphocyte activity by lupeol isolated from Crataeva religiosa

Lupeol has been shown to possess antiarthritic activity through possible suppression of the immune system. As seen in the following studies, it was found to suppress various immune factors such as the phagocytic (cell-killing) activity of macrophages, T-lymphocyte activity that included CD4+T cell mediated cytokine generation. Assessment of T cells and their intracellular content of cytokines was carried out by flow cytometric analysis in Balb/c mice. Oral administration of lupeol at doses of 12.5-200 mg/kg p.o. inhibited CD4+ T and CD8+ T cell counts and cytokines IL-2, IFN-gamma (Th1) and IL-4 (Th2). Cytometric bead array (CBA) technology was applied to carry out simultaneous measurement of multiple serum cytokines. The oral LD(0) in mice was more than 2 g/kg body weight.

Construction, purification, and characterization of a chimeric TH1 antagonist

Background

TH1 immune response antagonism is a desirable approach to mitigate some autoimmune and inflammatory reactions during the course of several diseases where IL-2 and IFN-γ are two central players. Therefore, the neutralization of both cytokines could provide beneficial effects in patients suffering from autoimmune or inflammatory illnesses.

Results

A chimeric antagonist that can antagonize the action of TH1 immunity mediators, IFN-γ and IL-2, was designed, engineered, expressed in E. coli, purified and evaluated for its in vitro biological activities. The TH1 antagonist molecule consists of the extracellular region for the human IFNγ receptor chain 1 fused by a four-aminoacid linker peptide to human 60 N-terminal aminoacid residues of IL-2. The corresponding gene fragments were isolated by RT-PCR and cloned in the pTPV-1 vector. E. coli (W3110 strain) was transformed with this vector. The chimeric protein was expressed at high level as inclusion bodies. The protein was partially purified by pelleting and washing. It was then solubilized with strong denaturant and finally refolded by gel filtration. In vitro biological activity of chimera was demonstrated by inhibition of IFN-γ-dependent HLA-DR expression in Colo 205 cells, inhibition of IFN-γ antiproliferative effect on HEp-2 cells, and by a bidirectional effect in assays for IL-2 T-cell dependent proliferation: agonism in the absence versus inhibition in the presence of IL-2.

Conclusion

TH1 antagonist is a chimeric protein that inhibits the in vitro biological activities of human IFN-γ, and is a partial agonist/antagonist of human IL-2. With these attributes, the chimera has the potential to offer a new opportunity for the treatment of autoimmune and inflammatory diseases.

B and T Lymphocyte Attenuator-Mediated Signal Transduction Provides a Potent Inhibitory Signal to Primary Human CD4 T Cells That Can Be Initiated by Multiple Phosphotyrosine Motifs

The B and T lymphocyte attenuator (BTLA) is a recently identified member of the CD28 family of cell receptors. Initial reports demonstrated that mice deficient in BTLA expression were more susceptible to experimental autoimmune encephalomyelitis, indicating that BTLA was likely to function as a negative regulator of T cell activation. However, cross-linking of BTLA only resulted in a 2-fold reduction of IL-2 production, questioning the potency with which BTLA engagement blocks T cell activation. We established a model in which BTLA signaling could be studied in primary human CD4 T cells. We observed that cross-linking of a chimeric receptor consisting of the murine CD28 extracellular domain and human BTLA cytoplasmic tail potently inhibits IL-2 production and completely suppresses T cell expansion. Mutation of any BTLA tyrosine motifs had no effect on the ability of BTLA to block T cell activation. Only mutation of all four tyrosines rendered the BTLA cytoplasmic tail nonfunctional. We performed structure-function studies to determine which factors recruited to the BTLA cytoplasmic tail correlated with BTLA function. Using pervanadate as a means to phosphorylate the BTLA cytoplasmic tail, we observed both Src homology protein (SHP)-1 and SHP-2 recruitment. However, upon receptor engagement, we observed only SHP-1 recruitment, and mutations that abrogated SHP-1 recruitment did not impair BTLA function. These studies question whether SHP-1 or SHP-2 have any role in BTLA function and caution against the use of pervanadate as means to initiate signal transduction cascades in primary cells.