A critical role of IL-2 for the production and gene transcription of IL-5 in allergen-specific human T cell clones

Immunostimulatory gene therapy targeting CD40, 4-1BB and IL-2R activates DCs and stimulates antigen-specific T-cell and NK-cell responses in melanoma models

BACKGROUND

The activation of dendritic cells (DCs) is pivotal for generating antigen-specific T-cell responses to eradicate tumor cells. Hence, immunotherapies targeting this interplay are especially intriguing. Moreover, it is of interest to modulate the tumor microenvironment (TME), as this harsh milieu often impairs adaptive immune responses. Oncolytic viral therapy presents an opportunity to overcome the immunosuppression in tumors by destroying tumor cells and thereby releasing antigens and immunostimulatory factors. These effects can be further amplified by the introduction of transgenes expressed by the virus.

METHODS

Lokon oncolytic adenoviruses (LOAd) belong to a platform of chimeric serotype Ad5/35 viruses that have their replication restricted to tumor cells, but the expression of transgenes is permitted in all infected cells. LOAd732 is a novel oncolytic adenovirus that expresses three essential immunostimulatory transgenes: trimerized membrane-bound CD40L, 4-1BBL and IL-2. Transgene expression was determined with flow cytometry and ELISA and the oncolytic function was evaluated with viability assays and xenograft models. The activation profiles of DCs were investigated in co-cultures with tumor cells or in an autologous antigen-specific T cell model by flow cytometry and multiplex proteomic analysis. Statistical differences were analyzed with Kruskal-Wallis test followed by Dunn's multiple comparison test.

RESULTS

All three transgenes were expressed in infected melanoma cells and DCs and transgene expression did not impair the oncolytic activity in tumor cells. DCs were matured post LOAd732 infection and expressed a multitude of co-stimulatory molecules and pro-inflammatory cytokines crucial for T-cell responses. Furthermore, these DCs were capable of expanding and stimulating antigen-specific T cells in addition to natural killer (NK) cells. Strikingly, the addition of immunosuppressive cytokines TGF-β1 and IL-10 did not affect the ability of LOAd732-matured DCs to expand antigen-specific T cells and these cells retained an enhanced activation profile.

CONCLUSIONS

LOAd732 is a novel immunostimulatory gene therapy based on an oncolytic adenovirus that expresses three transgenes, which are essential for mediating an anti-tumor immune response by activating DCs and stimulating T and NK cells even under imunosuppressive conditions commonly present in the TME. These qualities make LOAd732 an appealing new immunotherapy approach.

Protein phosphatase 1 is involved in IL-2-induced IL-5 and IL-13 expression in human T cells

IL-2 plays an important role in immunological and other biological functions. This cytokine directly induces the production of several cytokines, such as IL-5 and IL-13. The mechanisms of IL-2-mediated cytokine synthesis are mostly unclear; however, the involvement of IL-2 receptor (IL-2R)β has been suggested. In this study, the signaling molecule downstream of IL-2Rβ was investigated, employing a proteomic approach. Full-length IL-2Rβ and its mutant in which the intracellular component was truncated were introduced in an IL-2Rα- and IL-2Rγ-stably transfected T cell hybridoma, S1. The differential phosphorylation profiles of protein tyrosine residues in these cells upon IL-2 stimulation were examined by two-dimensional gel electrophoresis. The candidate phosphoproteins of interest were re-covered, in-gel digested and mass spectrometry fingerprinted. Among proteins specifically phosphorylated in full-length IL-2Rβ-expressing cells in response to IL-2 stimulation, protein phosphatase (PP)1β and FK506-binding protein 4 were identified. Particularly, PP1β augmented IL-5 and IL-13 expression stimulated by IL-2 but not by anti-CD3 antibody in human peripheral CD4+ T cells upon ectopic expression. IL-2-induced cytokine expression was suppressed by overexpression of PP1 regulatory subunit 2. A PP1 inhibitor, tautomycin, but not a PP2A inhibitor, okadaic acid, also inhibited the IL-2R-mediated responses. It was conclusively shown that PP1 is crucially involved in IL-2-mediated IL-5 and IL-13 synthesis in human T cells.

IL-2-induced IL-9 production by allergen-specific human helper T-cell clones

BACKGROUND

IL-9 is an important cytokine in allergic diseases such as asthma, atopic dermatitis, etc. T helper (Th) cells seem to be the main source of IL-9. Cellular and molecular mechanisms of IL-9 production by human Th cells have been poorly understood.

METHODS

Dermatophagoides farinae(Der f)-specific Th clones were established from peripheral blood lymphocytes of atopic asthmatics, and cytokine synthesis in response to various stimuli was determined by specific ELISAs.

RESULTS

IL-9 was produced by 14 of 27 human Th clones upon T cell receptor (TCR) stimulation, immobilized anti-CD3 antibody (Ab). IL-9 production was significantly enhanced by the addition of anti-CD28 Ab into the culture, indicating the role of costimulatory signal on IL-9 synthesis. Pharmacologically, IL-9 production was induced by ionomycin (IOM) alone, and enhanced by phorbol 12-myristate 13-acetate (PMA). rIL-2 induced IL-9 production by 8 out of 19 Th clones. IL-9 production by Th clones stimulated with immobilized anti-CD3 Ab was significantly suppressed by the addition of anti-IL-2 neutralizing Ab into the culture.

CONCLUSION

Approximately half of the Der f-specific Th clones derived from atopic asthmatics produced IL-9 upon TCR stimulation. Ca(2+) signal, CD28 signal, and IL-2 receptor signal seem to play important roles in IL-9 production by human Th cells. Moreover, synthesis of IL-9, a Th2 cytokine, is dependent on IL-2, a Th1 cytokine, which is produced by Th cells themselves.

Effect of home environment control on children with atopic or non-atopic asthma

BACKGROUND

Although allergen avoidance is known to be important for treating atopic diseases, there is a very limited amount of time for clinical education of patients on this topic.

METHODS

We compared the effect of the thorough home visit counseling (>60 minutes per visit) for avoiding house dust mites (HDMs) with that of regular guidance in our clinics (10 minutes per patient). We enrolled 36 children with asthma (7 years of age or younger; mean, 3.8) in this study under an informed consent. After enrolling the 24 patients for the home visit, 12 families were enrolled as controls for the regular clinical guidance. Between June 1995 and June 1996, we visited the homes of 24 children with asthma enrolled in this study every month and performed a thorough HDM-avoidance counseling of more than 60 minutes (home visit counsel) at each visit. We compared the effects of this counseling with those of the regular clinical guidance given (10 minutes per patient) to the remaining 12 children with asthma. We also evaluated the effect of home visit counseling on children of two subgroups, i.e., an atopic (with positive IgE antibody against HDM) and a non-atopic (without detectable IgE antibodies against 8 common allergens) subgroup.

RESULTS

Home visit counseling markedly reduced the frequencies of asthma attacks (p < 0.000001), the required theophylline dosages (p < 0.0005), and the levels of HDM allergens (p < 0.0005) in the atopic subgroups, whereas the effect of regular counseling on these 3 items was relatively less (p < 0.05 or not significant). Surprisingly, home visit counseling also markedly reduced the asthma attacks (p < 0.00001) and theophylline dosages (p < 0.00001) of children with non-atopic asthma.

CONCLUSIONS

These results suggest that thorough allergen avoidance counseling is effective for children with non-atopic asthma as well as atopic asthma.

Interleukin-6 promotes the production of interleukin-4 and interleukin-5 by interleukin-2-dependent and -independent mechanisms in freshly isolated human T cells

T helper 2 (Th2) cytokines [interleukin (IL)-4 and IL-5] play a central role in the development of allergic immune responses. After allergen provocation, the expression of Th2 cytokines is rapidly up-regulated in atopy and asthma. IL-6 is a multifunctional cytokine that is able to direct Th2 immune responses and is secreted by multiple tissue cell types. This study shows that IL-6 induces up-regulation of IL-4 and IL-5 after short (5 min) preincubation periods in freshly isolated, alpha-CD3/alpha-CD28-stimulated T cells. After longer preincubation periods with IL-6 (12 and 24 hr), the priming effect on IL-4 production gradually disappears, whereas the effect on IL-5 becomes more pronounced. In contrast, a small but significant inhibitory effect is found on the production of the Th1 cytokine interferon-gamma. Additional experiments indicate that the long-term priming effect of IL-6 on IL-5 production is dependent on IL-2 signalling. This is not the case for the short-term IL-6 effect on IL-5 secretion, where the p38 mitogen-activated protein kinase-dependent induction of activator protein-1 DNA-binding activity is involved, independent of signal transducer and activator of transcription 3 phosphorylation. In summary, these data demonstrate that the short-term and long-term priming effects of IL-6 on Th2 cytokine production are regulated by different mechanisms.

Control of IL-5 production by human helper T cells as a treatment for eosinophilic inflammation: comparison of in vitro and in vivo effects between selective and nonselective cytokine synthesis inhibitors

BACKGROUND

Helper T cells are involved in the pathophysiologic condition of asthma, so modulation of cytokine production may be effective therapy.

OBJECTIVE

We aimed to selectively control the synthesis of IL-5 by helper T cells and tested in vivo effects using a murine asthma model.

METHODS

The effect of dexamethasone, FK506, cyclosporin A, and nonactin (a macrolide compound produced by Streptomyces griseus) on cytokine production by allergen-specific T-cell clones was determined. The effect of these agents and an anti-IL-5 neutralizing antibody on airway eosinophilic inflammation was investigated in a murine asthma model.

RESULTS

Dexamethasone, FK506, and cyclosporin A suppressed the production of IL-2, IL-4, and IL-5 by human helper T cells, which shows a similar concentration-response relationship in each case. Cyclosporin A and dexamethasone inhibited airway eosinophilia in vivo. Nonactin suppressed IL-5 synthesis but not IL-2 or IL-4 synthesis, and it also significantly suppressed airway eosinophilia.

CONCLUSION

Nonactin only suppressed IL-5 synthesis and was as effective against eosinophilia as cyclosporin A and dexa-methasone, which indicates that IL-5 is a reasonable therapeutic target in allergic disorders that are accompanied by eosinophilic inflammation.

p38 Mitogen-Activated Protein Kinase Regulates Human T Cell IL-5 Synthesis

Involvement of p38 mitogen-activated protein (MAP) kinase in human T cell cytokine synthesis was investigated. p38 MAP kinase was clearly induced in human Th cells activated through the TCR. SB203580, a highly selective inhibitor of p38 MAP kinase, inhibited the induction of p38 MAP kinase in human Th cells. Major T cell cytokines, IL-2, IL-4, IL-5, and IFN-γ, were produced by Der f 2-specific Th clones upon stimulation through the TCR. IL-5 synthesis alone was significantly inhibited by SB203580 in a dose-dependent manner, whereas the production of IL-2, IL-4, and IFN-γ was not affected. The proliferation of activated T cells was not affected. IL-5 synthesis of human Th clones induced upon stimulation with rIL-2, phorbol ester plus anti-CD28 mAb, and immobilized anti-CD3 mAb plus soluble anti-CD28 mAb was also suppressed by SB203580 in the same concentration response relationship. The results clearly indicated that IL-5 synthesis by human Th cells is dependent on p38 MAP kinase activity, and is regulated distinctly from IL-2, IL-4, and IFN-γ synthesis. Selective control of IL-5 synthesis will provide a novel treatment devoid of generalized immune suppression for bronchial asthma and atopic dermatitis that are characterized by eosinophilic inflammation.

Secreted respiratory syncytial virus G glycoprotein induces interleukin-5 (IL-5), IL-13, and eosinophilia by an IL-4-independent mechanism

The attachment glycoprotein G of respiratory syncytial virus (RSV) is produced as both membrane-anchored and secreted forms by infected cells. Immunization with secreted RSV G (Gs) or formalin-inactivated alumprecipitated RSV (FI-RSV) predisposes mice to immune responses involving a Th2 cell phenotype which results in more severe illness and pathology, decreased viral clearance, and increased pulmonary eosinophilia upon subsequent RSV challenge. These responses are associated with increased interleukin-4 (IL-4) production in FI-RSV-primed mice, and the responses are IL-4 dependent. RNase protection assays demonstrated that similar levels of IL-4 mRNA were induced after RSV challenge in mice primed with vaccinia virus expressing Gs (vvGs) or a construct expressing only membrane-anchored G (vvGr). However, upon RSV challenge, vvGs-primed mice produced significantly greater levels of IL-5 and IL-13 mRNA and protein than vvGr-primed mice. Administration of neutralizing anti-IL-4 antibody 11.B11 during vaccinia virus priming did not alter the levels of vvGs-induced IL-5, IL-13, pulmonary eosinophilia, illness, or RSV titers upon RSV challenge, although immunoglobulin G (IgG) isotype profiles revealed that more IgG2a was produced. vvGs-priming of IL-4-deficient mice demonstrated that G-induced airway eosinophilia was not dependent on IL-4. In contrast, airway eosinophilia induced by FI-RSV priming was significantly reduced in IL-4-deficient mice. Thus we conclude that, in contrast to FI-RSV, the secreted form of RSV G can directly induce IL-5 and IL-13, producing pulmonary eosinophilia and enhanced illness in RSV-challenged mice by an IL-4-independent mechanism.

Cyclic AMP suppresses interleukin-5 synthesis by human helper T cells via the downregulation of the calcium mobilization pathway

1. To delineate the mechanism by which cyclic AMP (cAMP) suppresses interleukin (IL)-5 synthesis, the effects of prostaglandin (PG) E2, forskolin, dibutyryl (db)-cAMP and the Ca2+ ionophore, ionomycin on cytokine synthesis, proliferation and CD25 expression of human T cells were investigated. Further studies were performed by measurement of the intracellular concentrations of cyclic AMP ([cAMP]i) and Ca2+ ([Ca2+]i) and by electrophoretic mobility shift analysis (EMSA). 2. PGE2, forskolin and db-cAMP suppressed IL-5 production by human T cell line following T cell receptor (TCR)-stimulation. PGE2 suppressed TCR-induced messenger RNA (mRNA) expression of IL-2, IL-4 and IL-5, as well as proliferation and CD25 expression. 3. Cyclic AMP-mediated suppression of cytokine synthesis, proliferation and CD25 expression in human T cells were attenuated by ionomycin. 4. [cAMP]i was increased by PGE2 and forskolin. PGE2 suppressed the TCR-induced biphasic increase in [Ca2+]i. EMSA revealed that four specific protein-DNA binding complexes related to NF-AT were detected at the IL-5 promoter sequence located from -119 to -90 relative to the transcription initiation site. The slowest migrating complex induced by TCR stimulation was enhanced by PGE2 and further upregulated by ionomycin. Another binding which did not compete with cold AP-1 oligonucleotides, was constitutively present and was unaffected by PGE2 but enhanced by ionomycin. 5. The suppressive effect of cyclic AMP on human IL-5 synthesis is mediated by interference with intracellular Ca2+ mobilization but distinct from the NF-AT-related pathway.

Effects of cyclosporin A and dinactin on T-cell proliferation, interleukin-5 production, and murine pulmonary inflammation

We compared the effects of cyclosporin A (CSA) and a macrotetrolide antibiotic, dinactin, on human T-cell proliferation and cytokine production induced by stimulation of the T-cell receptor alone (monoclonal antibody [mAb] directed against CD3) or in combination with costimulatory signals (mAbs directed against CD3 and CD28). These agents were also examined in a murine model of interleukin (IL)-5-mediated pulmonary inflammation. Dinactin inhibited T-cell proliferation induced by IL-2, by mAb to CD3, and by mAbs to CD3 plus alpha-CD28 with identical dose-response curves (IC50 = 10-20 ng/ml). Dinactin inhibited cytokine production with IC50 values of 10 ng/ml for IL-4 and IL-5 and 30 or 60 ng/ml for interferon-gamma or IL-2, respectively. Unlike CSA, exogenous IL-2 did not alter the dinactin-mediated effects on T cells, and nuclear run-on and steady-state messenger RNA (mRNA) analysis showed that dinactin inhibited cytokine production through a post-transcriptional mechanism. CSA selectively blocked T-cell receptor-induced T-cell proliferation and cytokine production (IC50 = 10 ng/ml). Under costimulatory conditions, IL-5 synthesis was only minimally inhibited by high concentrations of CSA, and at CSA concentrations of less than 125 ng/ml, IL-5 was significantly increased above control values. Dinactin and CSA reduced pulmonary eosinophilia when administered within 1 d of airway antigen challenge. Of the cytokine mRNAs examined in the lungs of CSA-pretreated, antigen-challenged mice, IL-5 mRNA levels were the least reduced, paralleling the resistance of IL-5 to CSA observed in vitro and suggesting a role for CD28 in the in vivo induction of IL-5.

Elevation of serum IgE level and peripheral eosinophil count during T lymphocyte-directed gene therapy for ADA deficiency: implication of Tc2-like cells after gene transduction procedure

We have successfully carried out T-cell-directed gene therapy for a boy with severe combined immunodeficiency due to adenosine deaminase deficiency (ADA SCID) and unexpectedly found an elevation of serum IgE level and peripheral eosinophil count during the course. More than 90% of transduced cells cultured for 7-11 days before infusion into the patient were positive for CD8 and expressed Th2-type cytokine genes such as IL-4, IL-5 and IL-13. Furthermore, CD4(+) T-depleted PBMC (peripheral blood mononuclear cells) from the patient synthesized IgE in vitro by stimulation with IL-4. Collectively, these results suggested that Tc2-like cells in the transduced cells have distinct immunological functions to help IgE synthesis and activate eosinophils.

Interleukin-5 mRNA stability in human T cells is regulated differently than interleukin-2, interleukin-3, interleukin-4, granulocyte/macrophage colony-stimulating factor, and interferon-gamma

Interleukin-5 (IL-5) transcriptional activation and mRNA stability were investigated in a human TH0 T-cell clone (SP-B21) and in nonclonal CD4 TH2 cells, differentiated in vitro from peripheral blood T cells. Cells were stimulated with alpha-CD3 monoclonal antibody (mAb) with and without alpha-CD28 mAb. Comparison to other cytokine genes revealed aspects of mRNA regulation unique to IL-5. The half-life (t1/2) of IL-5 mRNA, determined by addition of actinomycin D (ActinoD) or cyclosporin A (CSA) was longer (by >= 2 h) than that of IL-2, IL-3, IL-4, interferon-gamma, or granulocyte/macrophage colony-stimulating factor. With the exception of IL-5, t1/2 values were significantly shorter with CSA as the transcriptional inhibitor than with ActinoD. The t1/2 value of IL-5 mRNA, but not the other cytokine transcripts, determined with either ActinoD or CSA, was longer than predicted from the kinetics of steady-state mRNA decline. Co-stimulation of both cell types with alpha-CD28 mAb increased the stability of cytokine transcripts weakly, and IL-5 remained the most stable transcript. Thus, the degradation pathway that targets IL-5 is distinct from the other cytokine transcripts measured and involves proteins whose transcription is blocked by ActinoD and CSA. From examination of the levels of transcription initiation (nuclear run-on assay) and steady-state mRNA attained in cultures stimulated in the presence of the protein synthesis inhibitor, cycloheximide, only IL-5 transcription initiation had an absolute dependency on new protein synthesis.