Differential regulation of interleukin 4 and interleukin 5 gene expression: a comparison of T-cell gene induction by anti-CD3 antibody or by exogenous lymphokines

Dysregulation of interleukin 5 expression in familial eosinophilia

BACKGROUND

Familial eosinophilia (FE) is a rare autosomal dominant inherited disorder characterized by the presence of lifelong peripheral eosinophilia (>1500/μL). Mapped to chromosome 5q31-q33, the genetic cause of FE is unknown, and prior studies have failed to demonstrate a primary abnormality in the eosinophil lineage.

OBJECTIVE

The aim of this study was to identify the cells driving the eosinophilia in FE.

METHODS

Microarray analysis and real-time PCR were used to examine transcriptional differences in peripheral blood mononuclear cells (PBMC), and in purified cell subsets from affected and unaffected family members belonging to a single large kindred. Cytokine levels in serum and PBMC culture supernatants were assessed by suspension array multiplexed immunoassays.

RESULTS

Whereas IL-5 mRNA expression was significantly increased in freshly isolated PBMC from affected family members, this was not accompanied by increased mRNA expression of other Th2 cytokines (IL-4 or IL-13). Serum levels of IL-5 and IL-5 receptor α, but not IgE, were similarly increased in affected family members. Of note, IL-5 mRNA expression was significantly increased in purified CD3+ CD4+, CD14+, CD19+, and ILC2 cells from affected family members, as were IL-5 protein levels in supernatants from both stimulated PBMC and ILC2 cultures.

CONCLUSIONS

These data are consistent with the hypothesis that the eosinophilia in FE is secondary to dysregulation of IL-5 production in PBMC (and their component subsets).

Inhibition of G-Protein βγ Signaling Decreases Levels of Messenger RNAs Encoding Proinflammatory Cytokines in T Cell Receptor-Stimulated CD4(+) T Helper Cells

Background: Inhibition of G-protein βγ (Gβγ) signaling was found previously to enhance T cell receptor (TCR)-stimulated increases in interleukin 2 (IL-2) mRNA in CD4⁺ T helper cells, suggesting that Gβγ might be a useful drug target for treating autoimmune diseases, as low dose IL-2 therapy can suppress autoimmune responses. Because IL-2 may counteract autoimmunity in part by shifting CD4⁺ T helper cells away from the Type 1 T helper cell (TH1) and TH17 subtypes towards the TH2 subtype, the purpose of this study was to determine if blocking Gβγ signaling affected the balance of TH1, TH17, and TH2 cytokine mRNAs produced by CD4⁺ T helper cells.

Methods: Gallein, a small molecule inhibitor of Gβγ, and siRNA-mediated silencing of the G-protein β₁ subunit (Gβ₁) were used to test the effect of blocking Gβγ on mRNA levels of cytokines in primary human TCR-stimulated CD4⁺ T helper cells.

Results: Gallein and Gβ₁ siRNA decreased interferon-γ (IFN-γ) and IL-17A mRNA levels in TCR-stimulated CD4⁺ T cells grown under TH1-promoting conditions. Inhibiting Gβγ also decreased mRNA levels of STAT4, which plays a positive role in TH1 differentiation and IL-17A production. Moreover, mRNA levels of the STAT4-regulated TH1-associated proteins, IL-18 receptor β chain (IL-18Rβ), mitogen-activated protein kinase kinase kinase 8 (MAP3K8), lymphocyte activation gene 3 (LAG-3), natural killer cell group 7 sequence (NKG7), and oncostatin M (OSM) were also decreased upon Gβγ inhibition. Gallein also increased IL-4, IL-5, IL-9, and IL-13 mRNA levels in TCR-stimulated memory CD4⁺ T cells grown in TH2-promoting conditions.

Conclusions: Inhibiting Gβγ to produce these shifts in cytokine mRNA production might be beneficial for patients with autoimmune diseases such as rheumatoid arthritis (RA), Crohn’s disease (CD), psoriasis, multiple sclerosis (MS), and Hashimoto’s thyroiditis (HT), in which both IFN-γ and IL-17A are elevated.

Salmonella enterica serovar Typhimurium infection-induced CD11b+ Gr1+ cells ameliorate allergic airway inflammation

Allergies are mainly characterized as an unrestrained Th2-biased immune response. Epidemiological data associate protection from allergic diseases with the exposure to certain infectious agents during early stages of life. Modulation of the immune response by pathogens has been considered to be a major factor influencing this protection. Recent evidence indicates that immunoregulatory mechanisms induced upon infection ameliorate allergic disorders. A longitudinal study has demonstrated reduced frequency and incidence of asthma in children who reported a prior infection with Salmonella. Experimental studies involving Salmonella enterica serovar Typhimurium-infected murine models have confirmed protection from induced allergic airway inflammation; however, the underlying cause leading to this amelioration remains incompletely defined. In this study, we aimed to delineate the regulatory function of Salmonella Typhimurium infection in the amelioration of allergic airway inflammation in mice. We observed a significant increase in CD11b+ Gr1+ myeloid cell populations in mice after infection with S. Typhimurium. Using in vitro and in vivo studies, we confirmed that these myeloid cells reduce airway inflammation by influencing Th2 cells. Further characterization showed that the CD11b+ Gr1+ myeloid cells exhibited their inhibitory effect by altering GATA-3 expression and interleukin-4 (IL-4) production by Th2 cells. These results indicate that the expansion of myeloid cells upon S. Typhimurium infection could potentially play a significant role in curtailing allergic airway inflammation. These findings signify the contribution of myeloid cells in preventing Th2-mediated diseases and suggest their possible application as therapeutics.

Transfer of a T-helper type 2 clone into conjunctiva induces corneal damage in mice

PURPOSE

We established a T-helper Type 2 (Th2) clone-induced conjunctival eosinophilia model by injecting D10.G.4.1 (D10) cells, a murine Th2 clone, and conalbumin, its specific antigen, into conjunctiva of AKR/J mice. Using this model, we investigated the effect of a coinjection of D10 cells and conalbumin into conjunctiva on corneal damage.

METHODS

Corneal fluorescein staining scores and eosinophil peroxidase (EPO) activity in conjunctiva were measured after coinjection of D10 and conalbumin into conjunctiva, and the effects of cyclosporine A, betamethasone, and anti-interleukin-5 antibody on staining scores and EPO activity were examined.

RESULTS

Coinjection of D10 and conalbumin induced an increase of the corneal fluorescein staining score after 24, 48, and 96 hours and 10 days. EPO activity in conjunctiva increased time-dependently until 24 hours after coinjection. The increase in the staining score followed the time dependent increase in EPO activity. The instillation of cyclosporine A, an inhibitor of cytokine production from T-cells, and betamethasone significantly inhibited the increase in corneal fluorescein score and EPO activity. Intraperitoneal administration of anti-interleukin-5 monoclonal antibody, which inhibits the infiltration of eosinophils into the conjunctiva, completely inhibited the increase in staining score.

CONCLUSION

The transfer of the Th2 clone into the murine conjunctiva induced corneal damage, which may have been caused by Th2 cell-produced interleukin-5 that mediated the activation of eosinophils.

Differential expression of interleukin-17A and -17F is coupled to T cell receptor signaling via inducible T cell kinase

T helper 17 (Th17) cells play major roles in autoimmunity and bacterial infections, yet how T cell receptor (TCR) signaling affects Th17 cell differentiation is relatively unknown. We demonstrate that CD4(+) T cells lacking Itk, a tyrosine kinase required for full TCR-induced phospholipase C-gamma (PLC-gamma1) activation, exhibit decreased interleukin-17A (IL-17A) expression in vitro and in vivo, despite relatively normal expression of retinoic acid receptor-related orphan receptor-gammaT (ROR-gammaT) and IL-17F. IL-17A expression was rescued by pharmacologically induced Ca(2+) influx or constitutively activated nuclear factor of activated T cells (NFAT). Conversely, decreased TCR stimulation or calcineurin inhibition preferentially reduced IL-17A expression. We further found that the promoter of Il17a but not Il17f has a conserved NFAT binding site that bound NFATc1 in wild-type but not Itk-deficient cells, even though both exhibited open chromatin conformations. Finally, Itk(-/-) mice also showed differential regulation of IL-17A and IL-17F in vivo. Our results suggest that Itk specifically couples TCR signaling to Il17a expression and the differential regulation of Th17 cell cytokines through NFATc1.

Cyclic AMP-induced chromatin changes support the NFATc-mediated recruitment of GATA-3 to the interleukin 5 promoter

Elevated intracellular cyclic AMP levels, which suppress the proliferation of naive T cells and type 1 T helper (Th1) cells are a property of T helper 2 (Th2) cells and regulatory T cells. While cyclic AMP signals interfere with the IL-2 promoter induction, they support the induction of Th2-type genes, in particular of il-5 gene. We show here that cyclic AMP signals support the generation of three inducible DNase I hypersensitive chromatin sites over the il-5 locus, including its promoter region. In addition, cyclic AMP signals enhance histone H3 acetylation at the IL-5 promoter and the concerted binding of GATA-3 and NFATc to the promoter. This is facilitated by direct protein-protein interactions involving the C-terminal Zn(2+)-finger of GATA-3 and the C-terminal region of the NFATc1 DNA binding domain. Because inhibition of NFATc binding to the IL-5 promoter in vivo also affects the binding of GATA-3, one may conclude that upon induction of Th2 effector cells NFATc recruits GATA-3 to Th2-type genes. These data demonstrate the functional importance of cyclic AMP signals for the interplay between GATA-3 and NFATc factors in the transcriptional control of lymphokine expression in Th2 effector cells.

Differential effects of IFN-alpha on the expression of various TH2 cytokines in human CD4+ T cells

BACKGROUND

In both human subjects and mice, T helper cells are classified into 2 subsets, TH1 and TH2 cells, on the basis of the cytokines they produce. Although IFN-alpha has been shown to enhance human TH1 responses, its influences on human TH2 responses have not yet been fully characterized. In addition, the mechanism for induction of TH1 responses by IFN-alpha has not been fully delineated.

OBJECTIVE

The present study was undertaken to explore the direct effects of IFN-alpha on the expression of various cytokines in human CD4+ T cells with a system using immobilized anti-CD3, which permits activation of CD4+ T cells in the complete absence of accessory cells.

METHODS

Highly purified CD4+ T cells obtained from healthy donors were stimulated with immobilized anti-CD3 with or without IFN-alpha and IL-12 in the complete absence of accessory cells. The production of cytokines was estimated by means of ELISA. The expression of mRNA for various cytokines, as well as transcription factors, was evaluated by using quantitative PCR.

RESULTS

IFN-alpha enhanced IL-4 protein and mRNA expression in immobilized anti-CD3-stimulated CD4+ T cells, irrespective of the presence of IL-12, whereas IFN-alpha suppressed the expression of IL-5 and IL-13. Of note, IFN-alpha enhanced the expression of mRNA for c-Maf, T-bet, and Fox-P3, irrespective of the presence of IL-12, but not that for GATA-3, in anti-CD3-stimulated CD4+ T cells.

CONCLUSION

These results indicate that IFN-alpha enhances the induction of TH1 responses through upregulation of T-bet mRNA expression, as well as the induction of TH2 responses through upregulation of c-Maf mRNA expression, followed by IL-4 expression. Moreover, the data also suggest that IFN-alpha might suppress the expression of IL-5 and IL-13 in differentiated TH2 cells.

Role of GATA-3 in IL-5 gene transcription by CD4+ T cells of asthmatic patients

BACKGROUND

Helper T cells and T cell cytokines play central roles in allergic disorders including bronchial asthma. We reported enhanced IL-5 production by peripheral blood T cells of asthmatic patients. A transcription factor, GATA-3, has been implicated in IL-5 gene expression. This study was undertaken to clarify the role of GATA-3 in the upregulation of IL-5 synthesis in asthmatic patients.

METHOD

Peripheral CD4+ T cells were transfected with an IL-5 promoter reporter construct as well as its mutants in the presence or absence of a GATA-3 expression vector. Messenger RNA expression level of GATA-3 in CD4+ T cells of asthmatic subjects was compared to that of healthy donors.

RESULTS

IL-5 promoter activity in CD4+ T cells was enhanced by overexpression of GATA-3, whereas it was diminished by the introduction of mutations in the putative GATA-3 binding sites. The GATA-3 expression level in CD4+ T cells of asthmatic patients was equivalent to that of healthy controls.

CONCLUSION

The expression level of GATA-3 may not be an essential factor to cause IL-5 hyperproduction in bronchial asthma, though GATA-3 is crucially involved in IL-5 gene transcription in human peripheral CD4+ T cells.

Effect of a novel interleukin-5 receptor antagonist, YM-90709 (2,3-dimethoxy-6,6-dimethyl-5,6-dihydrobenzo[7,8]indolizino[2,3-b]quinoxaline), on antigen-induced airway inflammation in BN rats

Interleukin-5 (IL-5) plays an important role in the activation of eosinophils in the allergic inflammation in conditions such as asthma, rhinitis, and atopic dermatitis. A newly synthesized compound, YM-90709 (2,3-dimethoxy-6,6-dimethyl-5,6-dihydrobenzo[7,8]indolizino[2,3-b]quinoxaline), was previously reported to inhibit the binding of IL-5 to its receptor (R) on human eosinophils and eosinophilic HL-60 clone 15 cells. However, it did not inhibit the binding of granulocyte-macrophage colony-stimulating factor (GM-CSF) to its receptor on the same cells. In this study, the intravenous injection of YM-90709 resulted in the inhibition of antigen-induced infiltration of eosinophils and lymphocytes, but not neutrophils or monocytes, into the bronchoalveolar lavage fluid (BALF) of Brown-Norway (BN) rats, with ED50 values of 0.32 mg/kg and 0.12 mg/kg, respectively. Two glucocorticoids, dexamethasone and prednisolone, inhibited neutrophil, eosinophil, and lymphocyte infiltration into the BALF. However, both significantly reduced the number of peripheral blood leukocytes and bone marrow leukocytes. In contrast, YM-90709 did not affect the peripheral blood leukocytes or the bone marrow leukocytes. These results indicate that, in this model, YM-90709, which is a novel IL-5 R antagonist, inhibits antigen-induced eosinophil and lymphocyte recruitment into the airway, without any suppressive effects on peripheral blood leukocytes or bone marrow leukocytes, in contrast to the glucocorticoids.

Distal regulatory elements play an important role in regulation of the human IL-5 gene

Eosinophil infiltration of the lung is a feature of both allergic and nonallergic asthma, and IL-5 is the key cytokine regulating the production and activation of these cells. Despite many studies focusing on the IL-5 promoter in both humans and mice there is as yet no clear picture of how the IL-5 gene is regulated. The aim of this study was to determine if distal regulatory elements contribute to appropriate regulation of the human IL-5 (hIL-5) gene. Activity of the -507/+44 hIL-5 promoter was compared to expression of the endogenous IL-5 gene in PER-117 T cells. The IL-5 promoter was not sufficient to reproduce a physiological pattern of IL-5 expression. Further, functional analysis of the 5' and 3' intergenic regions revealed a number of novel regulatory elements. We have identified a conserved enhancer located approximately 6.2 kb upstream of the hIL-5 gene. This region contains two potential GATA-3-binding sites and increases expression from the hIL-5 promoter by up to ninefold.

Specific activation of human interleukin-5 depends on de novo synthesis of an AP-1 complex

It is clear from the biology of eosinophilia that a specific regulatory mechanism must exist. Because interleukin-5 (IL5) is the key regulatory cytokine, it follows that a gene-specific control of IL5 expression must exist that differs even from closely related cytokines such as IL4. Two features of IL5 induction make it unique compared with other cytokines; first, induction by cyclic adenosine monophosphate (cAMP), which inhibits other T-cell-derived cytokines, and second, sensitivity to protein synthesis inhibitors, which have no effect on other cytokines. This study has utilized the activation of different transcription factors by different stimuli in a human T-cell line to study the role of conserved lymphokine element 0 (CLE0) in the specific induction of IL5. In unstimulated cells the ubiquitous Oct-1 binds to CLE0. Stimulation induces de novo synthesis of the AP-1 members JunD and Fra-2, which bind to CLE0. The amount of IL5 produced correlates with the production of the AP-1 complex, suggesting a key role in IL5 expression. The formation of the AP-1 complex is essential, but the rate-limiting step is the synthesis of AP-1, especially Fra-2. This provides an explanation for the sensitivity of IL5 to protein synthesis inhibitors and a mechanism for the specific induction of IL5 compared with other cytokines.

Characterization of YM-90709 as a novel antagonist which inhibits the binding of interleukin-5 to interleukin-5 receptor

Interleukin-5 (IL-5) plays an important role in the activation of eosinophils in allergic inflammation including asthma and atopic dermatitis. A newly synthesized compound, YM-90709, 2,3-dimethoxy-6,6-dimethyl-5,6-dihydrobenzo[7,8]indolizino [2,3-b]quinoxaline, is reported here to inhibit the binding of IL-5 to its receptor on peripheral human eosinophils and butyric acid-treated eosinophilic HL-60 clone 15 cells, with IC50 values of 1.0 and 0.57 microM, respectively. In contrast, YM-90709 did not affect the binding of granulocyte-macrophage colony-stimulating factor (GM-CSF) to its receptor on eosinophils and eosinophilic HL-60 clone 15 cells. In functional assays, YM-90709 inhibited IL-5-prolonged eosinophil survival with an IC50 value of 0.45 microM and did not affect the GM-CSF-prolonged eosinophil survival. Furthermore, YM-90709 inhibited the IL-5-induced but not GM-CSF-induced tyrosine phosphorylation of Janus kinase 2 (JAK2) in eosinophilic HL-60 clone 15 cells. These results indicate that YM-90709 is a novel IL-5 inhibitor which selectively blocks the binding of IL-5 to the IL-5 receptor (IL-5R).

Interleukin-5 in growth and differentiation of blood eosinophil progenitors in asthma: effect of glucocorticoids

1. There are increased numbers of circulating CD34(+) progenitor cells for eosinophils in patients with atopic asthma, with a further increase following allergen exposure or spontaneous worsening of asthma. We investigated the expression of IL-5 and IL-5Ralpha receptor in circulating CD34(+) progenitor cells in allergic asthmatics and the effects of corticosteroids. 2. Using double-staining techniques, up to 50% of CD34(+) cells expressed intracellular IL-5, and by RT - PCR, there was significant expression of IL-5 mRNA. When cultured in a semi-liquid methylcellulose medium, there were more eosinophil colony-forming units grown from asthmatic non-adherent mononuclear cell depleted of T cells in the presence of the growth factors GM-CSF, SCF and IL-3, but not of IL-5. 3. An anti-IL-5Ralpha receptor antibody and an anti-sense IL-5 oligonucleotide reduced the number of eosinophil colony forming units. No IL-5 mRNA or protein expression on T cells was observed in asthmatics or normal subjects. In the presence of growth factors including IL-5, there were significantly greater colony numbers with eosinophilic lineage grown from either asthmatics or normal subjects. 4. Dexamethasone (10(-6) M) suppressed IL-5 mRNA and protein expression in CD34(+) cells, and reduced eosinophil colony-forming units in asthmatics, but not in normal subjects. Dexamethasone did not change the expression of IL-5Ralpha on CD34(+) cells. 5. We conclude that there is increased expression of IL-5 on blood CD34(+) cells of patients with asthma and that this expression may auto-regulate eosinophilic colony formation from these progenitor cells. Corticosteroids inhibit the expression of IL-5 in circulating CD34(+) progenitor cells.

The role of IFN-gamma in the production of Th2 subpopulations: implications for variable Th2-mediated pathologies in autoimmunity

It has become increasingly apparent in studies of mutant mice and observations of disease that cytokine production by fully committed effector T cells within the Th1 and Th2 phenotype can vary within each group. This can potentially influence the type and effectiveness of a given immune response. The factors responsible for inducing variable Th1 and Th2 subtype responses have not been well established. Using transgenic mice expressing the myelin basic protein-specific TCR, we demonstrate here that two distinct populations of Th2 cells that are characterized primarily by differential IL-4 and IL-5 expression levels can be generated depending upon the levels of IFN-gamma present at the time of priming. We also demonstrate that populations expressing high levels of IL-4 relative to IL-5 vs those with intermediate levels of IL-4 relative to IL-5 are stable and possess distinct effector functions in an experimental autoimmune encephalomyelitis model.

Reduction of serum interleukin-5 levels reflect clinical improvement in patients with atopic dermatitis

Cytokines, in particular IL-4 and IL-5, regulate IgE synthesis and eosinophil activation in atopic dermatitis (AD). To elucidate whether the serum levels of IL-4 and IL-5 are related to the serum IgE level, eosinophilia, or clinical severity of the disease, 25 cases with AD were studied. Blood samples were isolated from two groups of donors: 1) patients with AD (n = 25); 2) non-allergic individuals (NA, n = 20) with serum IgE levels below 100 IU/ml and with blood eosinophil counts below 250/microliter. Each parameter was evaluated at least twice in AD patients at the beginning of the study and after 4, 8 or 12 weeks of treatment. IL-4 was hardly detected in AD and NA, but IL-5 was increased (> 10 pg/ml) in most cases (22/25) of AD group with 513.6 pg/ml as the mean. AD with normal serum IgE levels exhibited increased levels of IL-5, whereas AD with high serum IgE levels did not necessarily have elevated IL-5 levels. The IL-5 level tended to change in parallel with the clinical severity in each AD case, although the level itself was not correlated with the clinical severity per se. A significant decrease of IL-5 was observed in AD when the clinical severity decreased. Eosinophils also decreased along with the improvement of AD, whereas the serum level of IgE did not change during the observation period. Our results suggest that IL-5 is involved in the regulation of clinical courses of AD and that its kinetics at the serum level reflects the clinical activity of AD.

p38 MAP kinase and MKK-1 co-operate in the generation of GM-CSF from LPS-stimulated human monocytes by an NF-kappa B-independent mechanism

1. The extent to which the p38 mitogen-activated protein (MAP) kinase and MAP kinase kinase (MKK)-1-signalling pathways regulate the expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) from LPS-stimulated human monocytes has been investigated and compared to the well studied cytokine tumour necrosis factor-alpha (TNF alpha). 2. Lipopolysaccharide (LPS) evoked a concentration-dependent generation of GM-CSF from human monocytes. Temporally, this effect was preceded by an increase in GM-CSF mRNA transcripts and abolished by actinomycin D and cycloheximide. 3. LPS-induced GM-CSF release and mRNA expression were associated with a rapid and time-dependent activation of p38 MAP kinase, ERK-1 and ERK-2. 4. The respective MKK-1 and p38 MAP kinase inhibitors, PD 098059 and SB 203580, maximally suppressed LPS-induced GM-CSF generation by >90%, indicating that both of these signalling cascades co-operate in the generation of this cytokine. 5. Electrophoretic mobility shift assays demonstrated that LPS increased nuclear factor kappa B (NF-kappa B) : DNA binding. SN50, an inhibitor of NF-kappa B translocation, abolished LPS-induced NF-kappaB : DNA binding and the elaboration of TNFalpha, a cytokine known to be regulated by NF-kappaB in monocytes. In contrast, SN50 failed to affect the release of GM-CSF from the same monocyte cultures. 6. Collectively, these results suggest that the generation of GM-CSF by LPS-stimulated human monocytes is regulated in a co-operative fashion by p38 MAP kinase- and MKK-1-dependent signalling pathways independently of the activation of NF-kappa B.

Cytokine profile in minor salivary glands from patients with bronchial asthma

BACKGROUND

T lymphocytes are important components of the bronchial inflammatory cell infiltrate in asthma. Because lymphocytes activated in the respiratory tract recirculate to remote glandular and mucosal sites, we previously studied the histologic features of minor salivary glands (MSGs) in bronchial asthma and found an airway-like inflammation with T-lymphocyte infiltration, the presence of mast cells that were often degranulated, and basement membrane thickening but no eosinophil infiltration.

OBJECTIVE

We sought to investigate the cellular infiltration and cytokine profile in MSGs from untreated asthmatic subjects, steroid-treated asthmatic subjects, and control subjects and to compare these values with those found in bronchial biopsy specimens.

METHODS

The cellular infiltration was studied by using immunohistochemistry. Cytokine messenger (m)RNA expression for IL-4, IL-5, and IFN-gamma was determined by using in situ hybridization and cytokine immunoreactivity with immunohistochemistry.

RESULTS

A significant increase in CD4 and IL-4 mRNA(+) cells was observed in MSGs from asthmatic patients (both untreated and steroid-treated subjects) when compared with control subjects, which correlated with the clinical severity of asthma (FEV(1) and Aas score). In contrast to the bronchi, no IL-5 mRNA expression was observed in MSGs, and no difference was observed for MSG IFN-gamma mRNA between the groups. At the level of MSG protein expression, the 3 cytokines were seen, with a significant increase in IL-4 protein expression in steroid-treated asthmatic subjects compared with untreated asthmatic subjects and control subjects, but there were no differences between the groups in IL-5 and IFN-gamma protein expression.

CONCLUSION

The cytokine mRNA expression pattern observed in the MSGs of asthmatic subjects was different from that found in the bronchi, suggesting a different local immune regulation.

Protective role for interleukin-5 during chronic Toxoplasma gondii infection

To investigate the role of interleukin-5 (IL-5) during Toxoplasma gondii infection, IL-5 knockout (KO) mice and C57BL/6 control mice were infected intraperitoneally with ME49 cysts and the course of infection was monitored. The mortality rate during chronic infection was significantly greater in IL-5-deficient animals, and consistent with this finding, the KO mice harbored a greater number of brain cysts and tachyzoites than did their wild-type counterparts. Although the IL-5 KO animals did not succumb until late during infection, increased susceptibility, as measured by accelerated weight loss, was detectable during the acute stages of infection. The amounts of total immunoglobulin (Ig), IgM, and IgG2b were comparable in both strains, while the amount of IgG1 was much smaller in IL-5 KO mice. Spleen cell production of IL-12 in response to T. gondii antigen was approximately threefold lower in the KO strain, and this decrease correlated with a selective loss of B lymphocytes during culture. A link between the presence of B cells and augmented IL-12 production was established by the finding that after removal of B cells with monoclonal antibody and complement, wild-type- and KO-derived cells produced equivalent levels of IL-12 in response to T. gondii antigen. These results demonstrate a protective role of IL-5 against T. gondii infection and suggest that IL-5 may play a role in the production of IL-12.

Establishment of T-helper type 2 clone-induced eosinophilia in mouse conjunctiva

Eosinophil infiltration is one of the aspects of the inflammatory response to an allergen. The aim of this study was to establish T-helper type-2 (Th2)-induced conjunctival eosinophilia in mice to evaluate the effect of anti-allergic drugs. Th2 clone, D10.G4.1. (D10) with its specific antigen, conalbumin was co-injected into conjunctival tissue in mice. At 3-6 hr after D10 injection, eosinophil and neutrophil recruitment into conjunctival tissue was observed. Cellular infiltration into conjunctival tissue reached a maximum level between 24-48 hr after D10 injection. The number of eosinophils which infiltrated after 24 hr was dose dependent on T cell injection titer from 1x10(4), 1x10(5)to 1x10(6)cells site-1. The ratio of eosinophils to neutrophils at 24 hr after D10 cell (1x10(5)cells site-1) injection was about 9 to 1. The eosinophil infiltration into conjunctival tissue was significantly reduced by the intraperitoneal administration of anti-IL-5 monoclonal antibody (100 micrograms animal-1). Anti-IL-4 monoclonal antibody (500 micrograms animal-1) partially inhibited eosinophilia. The combined inhibitory effect of anti-IL-4 and anti-IL-5 monoclonal antibodies was larger than the inhibitory effect of anti-IL-5 monoclonal antibody alone. In conclusion, a Th2-induced mouse conjunctival eosinophilia model was established in which D10 activation results in IL-4 and IL-5 release. These cytokines elicit eosiniophil infiltration. This response shows that the model will be effective for screening candidates of anti-allergic drugs.

Relative abilities of 4-1BB (CD137) and CD28 to co-stimulate the response of cytokine deflected Th1 and Th2 cells

In this report we show that allo-stimulated naïve CD4+ cells when cultured in IL-2, IFN-gamma, IL-12 and anti-IL-4 differentiated into Th1 cells expressing very low amounts of 4-1BB molecule, but high amounts of CD28. By contrast, allo-stimulated naive CD4+ cells cultured in the presence of exogenous IL-2, IL-10, IL-4 and anti-INF-gamma evolved into Th2 expressing high amounts of both 4-1BB and CD28. Various Th1/Th2 clones derived from limiting dilution also exhibited similar expression pattern. This differential expression of co-stimulatory molecules on Th subsets account for the ability of 4-1BB to trigger both the proliferation and production of IL-4 by Th2 cells only and for the ability of CD28 to trigger proliferation and typical secretion in both Th1 and Th2 cells.

Regulation of the human interleukin-5 promoter by Ets transcription factors. Ets1 and Ets2, but not Elf-1, cooperate with GATA3 and HTLV-I Tax1

Interleukin-5 (IL-5), expressed primarily by type-2 T helper (Th2) cells, plays an important role in the development of allergic diseases, such as allergic asthma. Studying the regulation of IL-5 gene expression by Ets transcription factors, we found that Ets1 and Ets2, but not Elf-1, were able to activate the human IL-5 promoter in Jurkat T-cells. This required the presence of either phorbol 12-myristate acetate (PMA) plus ionomycin or PMA plus the viral protein HTLV-I Tax1. By mutation studies, it could be shown that Ets1 and Ets2 exerted their effects on the IL-5 promoter through a GGAA motif within the Cle0 element. In myeloid Kasumi cells, Ets1 and Ets2 failed to stimulate IL-5 promoter activity, unless the T-cell specific transcription factor GATA3 was added. These results show, for the first time, that Ets1 and Ets2 are able to cooperate with GATA3. Both ionomycin and Tax1 increased the combined effect of GATA3 with Ets1 and Ets2 in the presence of PMA. The data further demonstrate that, in addition to Ets1, Ets2 is also able to functionally cooperate with Tax1. The synergism of GATA3 with either Ets1 or Ets2 may play an important role in calcium- or Tax1-dependent regulation of IL-5 expression in Th2 cells or in HTLV-I transformed adult T-cell leukemia cells, respectively.

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.

Characterization of the mouse interleukin-5 promoter in a mouse TH2 T cell clone

The proximal mouse IL-5 promoter was examined using a mouse TH2 clone stimulated through the T cell receptor using anti-CD3 monoclonal antibody. DNase I protection defined four protein binding regions [IL-5RE-A, -69/-45; -B, (-90/-76); -C, (-154/-130); and -D (-176/-157)]. Stimulation-dependent binding, which was seen in the IL-5RE-B, -D regions and the 5' end of tIL-5RE-A, did not require new protein synthesis inhibitor during cell activation. EMSA using probes targeted to the IL-5RE-B, -C, -D regions demonstrated the multimeric nature of the bound proteins. By transfection analysis using a series of truncated IL-5 promoter-luciferase constructs, IL-5RE-C and -D contributed little to constitutive or inducible activity. The CLE0 site in the IL-5RE-A region contributed to full transcriptional activity but was not sufficient to mediate full activity. Full stimulation-dependent activity required the IL-5RE-B region and/or the GATA site (-70/-60).

Galectin-3 Down-Regulates IL-5 Gene Expression on Different Cell Types

Galectin-3 is an animal lectin, formerly named ε-binding protein or Mac-2, which has been described to play an important role in some inflammatory processes by the implication of different cells and the increase in cell adhesion functions through laminin binding activity. In this work we analyzed the role of galectin-3 in the modulation of Th2 cytokines that have an important role in the development of the inflammatory response. We have found that the addition of galectin-3 to human eosinophils, the eosinophilic cell line EoL-3, PBMC, and an Ag-specific T cell line (CD4+) produced a selective inhibition of IL-5 transcription. No inhibitory effect was found on the IL-4 mRNA transcription rate. The inhibitory effect on IL-5 transcription was reversed by incubation with lactose and using specific Ab against galectin-3. Galectin-3 is able to induce inhibition of the IL-5 released in the supernatants from PBMC stimulated with phorbol 12,13-dibutyrate and anti-CD3. Similar results were obtained when a T-specific cell line was stimulated with Ag. Also, EoL-3 stimulated with anti-CD32 produced IL-5 protein, the synthesis of which was partially inhibited by galectin-3. The present results demonstrate that galectin-3 induces a selective down-regulation of IL-5 expression in different cell types, opening important new possibilities in the regulation of the allergic reactions.

The profile of the cytokines secreted during the generation of T-helper cells from atopic asthmatic subjects

This study investigated cytokine release by T-cell lines from atopic and nonatopic individuals in the presence of specific aeroallergen. Cell lines from atopic and nonatopic individuals secreted IL-2 for less than 14 and more than 21 days, respectively. All of the atopic, but not the nonatopic, cell lines exhibited a biphasic peak in IL-4 and IL-5 secretion. Flow cytometry revealed that, after 35 days, 89.3% of the atopic cells were T helpers and 73.2% were activated. Only 7.4% of the nonatopic cells displayed activation markers. In conclusion, T-cell differentiation may be controlled by other factors in addition to stimulation by aeroallergens.

Biological and molecular characteristics of interleukin-5 and its receptor

Interleukin-5 (IL5) is a T cell-derived cytokine involved in the pathogenesis of atopic diseases. It specifically controls the production, the activation and the localization of Eosinophils. The Eosinophils are the major cause of tissue damage resulting in the symptoms of asthma and related allergic disorders. T cells purified from bronchoalveolar lavage and peripheral blood of asthmatics secrete elevated amount of IL5. Therefore IL5 emerges to be an attractive target for the generation of new anti-allergic drugs. Agents which inhibit either the production or the activity of IL5 could be expected to ameliorate the pathological effects of the allergic response. A better understanding of the biology of IL5 and the regulation of its expression is, however, a prerequisite for the development of new therapeutic agents. This review covers the major biological, molecular and structural aspects of IL5 research since the identification of this cytokine ten years ago.

Lymphoproliferative Disease in Human Peripheral Blood Mononuclear Cell-Injected SCID Mice. IV. Differential Activation of Human Th1 and Th2 Lymphocytes and Influence of the Atopic Status on Lymphoma Development

Intraperitoneal transfer of PBMC from EBV+ donors into SCID mice leads to high human Ig levels in mouse serum and B cell lymphoproliferative disease. As these events depend on the activation of coinjected human T cells, we addressed the behavior of the Th1 and Th2 subsets in this model. Production of IFN-γ, but not of Th2 cytokines such as IL-4, was detected in culture supernatants of PBMC stimulated in vitro with mouse splenocytes. Moreover, anti-CD3 stimulation of the human cells recovered from mice brought about IFN-γ, but not IL-4, synthesis; on the other hand, PCR and in situ hybridization analysis of ex vivo-recovered cells disclosed the presence of mRNA for both cytokines following in vitro restimulation, thus suggesting post-transcriptional regulation of IL-4 gene expression. When SCID mice were inoculated with PBMC from atopic donors, whose Th1/Th2 profile displays an imbalance toward Th2 cells, tumor development rates were lower, and tumor latency was higher, compared with those in mice injected with PBMC from normal donors. Isotypic analysis of human Ig in mouse serum showed the exclusive presence of IFN-γ-driven IgG subclasses; in addition, human IgE were low or undetectable in most cases. These findings indicate that following transfer into SCID mice, human Th1 lymphocytes undergo preferential activation, whereas Th2 function is down-regulated. Th1 lymphocytes probably are a major component in promoting EBV+ B cell expansion and tumor development; the individual Th1/Th2 profile could in part account for the as yet unexplained donor variability in tumor generation in this experimental model.

Transcription factor GATA-3 is differentially expressed in murine Th1 and Th2 cells and controls Th2-specific expression of the interleukin-5 gene

Interleukin-5 (IL-5), which is produced by CD4(+) T helper 2 (Th2) cells, but not by Th1 cells, plays a key role in the development of eosinophilia in asthma. Despite increasing evidence that the outcome of many diseases is determined by the ratio of the two subsets of CD4(+) T helper cells, Th1 and Th2, the molecular basis for Th1- and Th2-specific gene expression remains to be elucidated. We previously established a critical role for the transcription factor GATA-3 in IL-5 promoter activation in EL-4 cells, which express both Th1- and Th2-type cytokines. Our studies reported here demonstrate that GATA-3 is critical for expression of the IL-5 gene in bona fide Th2 cells. Whereas mutations in the GATA-3 site abolished antigen- or cAMP-stimulated IL-5 promoter activation in Th2 cells, ectopic expression of GATA-3 in Th1 cells or in a non-lymphoid, non-IL-5-producing cell line activated the IL-5 promoter. During the differentiation of naive CD4(+) T cells isolated from T cell receptor transgenic mice, GATA-3 gene expression was up-regulated in developing Th2 cells, but was down-regulated in Th1 cells, and antigen- or cAMP-activated Th2 cells (but not Th1 cells) expressed the GATA-3 protein. Thus, GATA-3 may play an important role in the balance between Th1 and Th2 subsets in immune responses. Inhibition of GATA-3 activity has therapeutic potential in the treatment of asthma and other hypereosinophilic diseases.

An interleukin 5 mutant distinguishes between two functional responses in human eosinophils

Interleukin 5 (IL-5) is the key cytokine involved in regulating the production and many of the specialized functions of mature eosinophils including priming, adhesion, and survival. We have generated a point mutant of human IL-5, IL-5 (E12K), which is devoid of agonist activity in both a TF-1 cell proliferation assay and a human eosinophil adhesion assay. However, IL-5 (E12K) is a potent and specific antagonist of both these IL-5-dependent functional responses. In both receptor binding and cross-linking studies the wild-type and IL-5 (E12K) mutant exhibit virtually identical properties. This mutant protein was unable to stimulate tyrosine phosphorylation in human eosinophils, and blocked the phosphorylation stimulated by IL-5. In contrast, IL-5 (E12K) is a full agonist in a human eosinophil survival assay, although with reduced potency compared to the wild-type protein. This IL-5 mutant enables us to clearly distinguish between two IL-5-dependent functional responses and reveals distinct mechanisms of receptor/cellular activation.

Identification of transcription factor binding sites important in the regulation of the human interleukin-5 gene

This study identifies three regions of the human interleukin (IL)-5 promoter involved in binding nuclear factors from activated T cells. DNase I footprinting and mobility shift assays with nuclear proteins from the human T cell clone, SP-B21, demonstrated protein interactions with each of these response elements (REs), located between positions -79 and -45 (RE-I), -123 and -92 (RE-II), and -170 and -130 (RE-III). Two of these regions, RE-II and RE-III, have not previously been described to regulate IL-5 expression in T cells. The RE-II site was shown to be critical for inducible IL-5 promoter activity in transient transfection assays in D10.G4.1 T cells, while the RE-III site functions as a negative regulatory element. The activity of the RE-II site was specifically inhibited by cyclosporin A, and transfection assays with IL-5 constructs containing mutations in the RE-II site showed greatly reduced reporter gene activity. We have defined the sequence involved in stimulation-dependent transcription and have identified constitutive as well as inducible DNA-binding protein complexes that bind to RE-II. Antibodies against at least two members of the nuclear factor of activated T cells (NFAT) family of transcription factors are capable of binding to the IL-5 RE-II complexes, although they can be distinguished from previously identified NFAT-specific complexes by several characteristics.

Major histocompatibility complex regulation of cytokine production

This review describes the phenomenon of the major histocompatibility complex (MHC) control of cytokine production both in experimental animals and in humans. H-2 (mouse MHC) regulates which type of cytokine is selectively produced in response to the hapten trinitrophenyl (TNP). T cells from TNP-immune H-2k mice produce interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-3, IL-5, tumor necrosis factor-alpha (TNF-alpha), IL-10, and very low levels of IL-4 on reexposure to the specific antigen in vitro. By contrast, T cells from H-2d mice produce IL-3, TNF-alpha, IL-10, and IL-4 but very low levels of IL-2, IL-5 and IFN-gamma. As MHC-congenic matched strains (BALB/k and BALB/c) are used, this makes it unlikely that non-MHC genes influence the class of response observed. A similar pattern of haplotype regulation of cytokine production is observed in humans. In fact, peripheral blood mononuclear cells from HLA-B8,DR3-positive and negative individuals differ in their ability to produce IL-2, IL-5, and IFN-gamma on stimulation with the mitogen phytohemagglutinin while producing similar amounts of IL-4, IL-6, and IL-10. The following main considerations emerge from these observations. The MHC/peptide complex generated after antigen immunization, indicates which class of cytokine production is preferentially induced and, therefore, the outcome of the immune response. Furthermore, MHC genotype may affect cytokine production (and then immune responses) by completely different mechanism(s), that is, by an antigen-nonspecific control that does not depend on the ability of MHC molecules to bind in different ways the different peptides. Accurate control of the functional repertoire of an immune response is a critical parameter in response to infections as well as in immunopathology. MHC control of the class of the immune response at the level of cytokine production is a sophisticated way in which this occurs. This control might be involved in adaptive immune responses to infections as well as in immunopathology.

Dissociation of production of interleukin-4 and interleukin-5

Interleukin-4 (IL-4) and IL-5 are cytokines with important roles in IgE production and eosinophilia. Interleukin-4 is essential for IgE production, and IL-5 is the major factor involved in the production and activation of eosinophils. These two phenomena commonly occur together in parasitic infestation and allergic disease. Both cytokines are produced by T helper 2 (Th2) and Th0 cells but not by Th1 cells, and in a number of experimental systems IL-4 is required for the production of IL-5. This article presents evidence that IL-4 and IL-5 are not always co-ordinately produced. There is evidence for selective production of either IL-4 or IL-5 in response to immune stimulation by different adjuvants. Dissociation of production of these two cytokines has also been reported in several pathological situations. An example is intrinsic or non-atopic asthma, with eosinophilic bronchitis but without elevated IgE production, where there is evidence for excessive production of IL-5 but not IL-4. Different microenvironmental factors may favour production of either IL-4 or IL-5. For example, IL-2 stimulates the production of IL-5 but not IL-4. Therefore the Th2 model does not account for all immune responses involving IL-4 or IL-5. Responses characterized by IL-4 without IL-5, and IL-5 without IL-4, can also occur.

How is expression of the interleukin-5 gene regulated?

Eosinophilia is a uniquely specific phenomenon regulated by interleukin-5 (IL-5), suggesting specific control for IL-5 expression. However in eosinophilia IL-5 is often co-expressed with other lymphokines such as IL-4, indicating that common, as well as independent, control mechanisms must exist. IL-5 gene expression is regulated at the transcriptional level. The molecular analysis of the IL-5 promoter region reveals the presence of positive regulatory sites that are common to many lymphokine genes. Results from immunosuppression studies suggest that the key control mechanism of IL-5 regulation may not depend on specific regulatory factors but on how gene expression is activated.

Recombinant interferon-alpha selectively inhibits the production of interleukin-5 by human CD4+ T cells

The effects of recombinant IFN-alpha on the production of IL-5 by human CD4+ T cells were first analyzed on resting CD4+ T cells purified from normal PBMC and stimulated either with a combination of PMA and anti-CD28 mAb or anti-CD3 mAb cross-linked on B7-1/CD32-transfected mouse fibroblasts. We found that IFN-alpha profoundly inhibited in a dose-dependent manner IL-5 production by resting CD4+ T cells whereas IL-10 was upregulated in both systems. The addition of a neutralizing anti-IL-10 mAb to PMA and anti-CD28 mAb upregulated IL-5 production by resting CD4+ T cells but did not prevent IFN-alpha-induced IL-5 inhibition. We then analyzed the effect of IFN-alpha on the production of cytokines by differentiated type 2 helper (Th2) CD4+CD3- cells isolated from peripheral blood of two patients with the hypereosinophilic syndrome. In both cases, IFN-alpha markedly inhibited IL-5 production while it induced mild upregulation of IL-4 and IL-10. Finally, the inhibitory effect of IFN-alpha on IL-5 production was confirmed on a panel of Th2 and Th0 clones generated in vitro. In 2 out of 6 clones, IL-5 inhibition was associated with upregulation of IL-4 and IL-10. We conclude that IFN-alpha selectively downregulates IL-5 synthesis by human CD4+ T cells.

Activation of the interleukin-5 promoter by cAMP in murine EL-4 cells requires the GATA-3 and CLE0 elements

Interleukin-5 (IL-5) plays a central role in the growth and differentiation of eosinophils and contributes to several disease states including asthma. Accumulating evidence suggests a role for cAMP as an immunomodulator; agents that increase intracellular cAMP levels have been shown to inhibit production of cytokines predominantly produced by T helper (Th) 1 cells such as IL-2 and interferon gamma (IFN-gamma). In contrast, the production of IL-5, predominantly produced by Th2 cells, is actually enhanced by these agents. In this report, we have performed transient transfection experiments with IL-5 promoter-reporter gene constructs, DNase I footprinting assays, and electrophoretic mobility shift assays to investigate the key regulatory regions necessary for activation of the IL-5 promoter by dibutyryl cAMP and phorbol esters in the mouse thymoma line EL-4. Taken together, our data demonstrate the critical importance of two sequences within the IL-5 5'-flanking region for activation by these agents in EL-4 cells: one, a highly conserved 15-base pair element present in genes expressed by Th2 cells, called the conserved lymphokine element 0 (CLE0; located between -53 and -39 in the IL-5 promoter), and the other, two overlapping binding sites for the transcription factor GATA-3 (but not GATA-4) between -70 and -59. Taken together, our data suggest that activation via the unique sequence combination GATA/CLE0 results in selective expression of the IL-5 gene in response to elevated levels of intracellular cAMP.

Transcription of the murine interleukin 5 gene is regulated by multiple promoter elements

Cis-acting regions in the 5'-flank of the mouse interleukin 5 (IL-5) gene involved in the specific and inducible regulation of IL-5 transcription in an untransformed mouse T cell clone, D10.G4.1, have been identified. Transient transfection assays with a series of deletion IL-5 promoter reporter constructs indicate that multiple regulatory elements in the 5'-flanking region of the IL-5 promoter play a role in regulating IL-5 transcription in Th2 cells. Negatively acting elements, NRE I and NRE II, map to the regions between positions -431 and -392 and positions -300 and -261. A positive regulatory element has been mapped to the region between positions -224 and -81. The activity of these elements is dependent on activation of the cells. A 40-bp sequence within this region, termed the IL-5 PRE, has been shown to bind at least two specific nuclear protein complexes from unstimulated and stimulated D10.G4.1 cells. An additional protein complex specific for this site has been identified in nuclear fractions from cells stimulated in the presence of the protein synthesis inhibitor, cycloheximide. Proteins that bind to these elements are likely to be important inducible and specific factors essential for control of IL-5 transcription in response to T cell receptor-mediated signaling events.

Characterization of the human interleukin-5 gene promoter: involvement of octamer binding sites in the gene promoter activity

To investigate the human interleukin (IL)-5 gene promoter, we have constructed a plasmid with the firefly luciferase reporter gene linked to human IL-5 5' flanking sequence (nucleotides -507 to +44). We have used this plasmid to transfect the mouse EL4 T cell line, which can, under certain conditions, produce IL-5 transcripts. Phorbol 12-myristate 13-acetate, A23187 and N6, 2'-O-dibutyryl-adenosine 3':5'-cyclic monophosphate co-stimulation of EL4 cells transfected with the human IL-5/luciferase reporter gene construct resulted in maximal induction of the luciferase gene. Deletion analysis of the IL-5 promoter revealed the presence of negative regulatory elements between nucleotides -404 and -312 and two regions, located between nucleotides -312 and -227 and between nucleotides -80 and -35, that are involved in the positive regulation of the IL-5 promoter. Using electrophoretic mobility shift assays, we show that the positive element located between nucleotides -312 and -227 involves the binding of factors antigenically related to Oct1, Oct2A and Oct2B, to a perfect octamer motif located at position -244/-237. Introduction of three point mutations in the octamer motif of the IL-5/luciferase reporter gene plasmid, which results in the loss of competition for the factors binding to the IL-5 promoter sequence, reduced the production of luciferase from stimulated, transfected EL4 cells, by 90%. Octamer factors can also bind within the second positive regulatory region.

Regulation of interleukin-5 and granulocyte-macrophage colony-stimulating factor expression

This review concerns the regulation of expression of the two main eosinophil differentiating factors, interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The latter, GM-CSF, is expressed in a wide variety of differentiated and non-differentiated cell types: T cells, monocytes, macrophages, fibroblasts, and endothelial cells. On the other hand, IL-5 is only expressed by a limited number of fully differentiated cells: eosinophils, mast cells, and a subset of T cells. Activation of GM-CSF in T cells and non-T cells occurs by different mechanisms, regulated both transcriptionally and post-transcriptionally. The transcriptional activation of GM-CSF via protein kinase C pathway and via viral transactivating proteins involves different regulatory elements of its promoter. Although one of these cis acting elements is common to IL-5, the activation of IL-5 apparently proceeds via different mechanism(s).

Th2 cell clonal anergy as a consequence of partial activation

We have demonstrated Th2 clonal anergy as a consequence of partial T cell activation by immunogenic peptide and chemically fixed APC, as well as by altered peptide ligand and live antigen-presenting cells (APC). Either stimulation resulted in a profound inability of the T cells to proliferate upon restimulation with antigen and functional APC, a similar phenomenon to that found with Th1 cells. The anergic state was long lasting and was restricted to proliferation, since the T cells retained the ability to produce cytokines upon restimulation, albeit at slightly reduced levels. Th2 anergy induction was inhibited by cyclosporine A, but not by provision of exogenous costimulation or growth factors. The data presented unify Th1 and Th2 cells with regard to anergy and suggest that the fundamental control during anergy for both subsets is prevention of clonal expansion, thus blocking amplification of the immune response.

Influence of CD28 co-stimulation on cytokine production is mainly regulated via interleukin-2

Interaction of CD28 with its ligand B7 plays an important role in the initiation of immune responses. The co-stimulatory signal generated by cross-linking of CD28 molecules results in enhanced T-cell proliferation and augmentation of cytokine production. In particular, mRNA levels of T-helper 1 (Th1)-type cytokines, such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) are reported to be strongly increased. We investigated the effect of CD28 co-stimulation on the production of Th2-type cytokines. CD28 mAb induced a strong augmentation of IL-2 secretion in activated T-cell clones. Production of IFN-gamma was also enhanced, but the increase in IL-4 secretion was generally moderate. Augmentation of IL-4 production by CD28 was most pronounced in clones that produced low amounts of IL-2, compared to clones producing high levels of IL-2. It was found that the up-regulation of IL-4 by CD28 co-stimulation was mainly controlled indirectly via an increase of IL-2. Some clones could produce IL-4 in an IL-2-independent manner; in these situations CD28 co-stimulation had no augmenting effect on the production of IL-4. The secretion of IL-4 by peripheral blood CD4+ T cells, that were activated with B7-expressing transfectants, was also found to be dependent on IL-2. Finally, Northern blot analysis confirmed that co-stimulation of CD28 primarily affected IL-2 production, and that inhibition of IL-2/IL-2 receptor interaction abolished the augmenting action of CD28 monoclonal antibody on the production of the Th2-type cytokines IL-4, IL-5 and IL-10 and of the Th1 cytokine IFN-gamma.

Evidence for an abnormal profile of interleukin-4 (IL-4), IL-5, and gamma-interferon (gamma-IFN) in peripheral blood T cells from patients with allergic eosinophilic gastroenteritis

Allergic eosinophilic gastroenteritis is characterized by elevated total IgE, specific IgE to food antigens, and eosinophilia of tissue and blood. Because the lymphokines IL-4, IL-5, and gamma-interferon, regulate IgE synthesis, and eosinophilopoiesis in vitro, we examined whether there is an imbalance in their production in allergic eosinophilic gastroenteritis. To explore this hypothesis, three adult patients with allergic eosinophilic gastroenteritis were studied. Flow cytometric studies of peripheral blood mononuclear cells from these patients did not reveal evidence of T cell activation or disturbance of T cell numbers or subsets. T cells were capable of normal mitogenic activation in vitro. IL-4 and IL-5 production were markedly elevated with mitogenic stimulation. Most IL-4 and IL-5 production was by CD4+ T cells. Synthesis of IL-5 by CD4+ T lymphocytes in three patients and CD8+ T lymphocytes in two patients occurred in the absence of mitogen. Mitogen-stimulated GM-CSF and gamma-interferon synthesis by CD4+ T cells was normal. Lymphokine mRNA in total cellular RNA derived from endoscopic biopsies was examined by reverse transcription/polymerase chain reaction. Mucosal biopsies from control subjects and most biopsies from allergic eosinophilic gastroenteritis patients contained less than 10(-8) micrograms IL-5 mRNA/1 microgram total cellular mRNA. gamma-Interferon mRNA was not detected by reverse transcription/polymerase chain reaction in biopsies from patients with allergic eosinophilic gastroenteritis but was present in controls. These lymphokine abnormalities are consistent with the elevated IgE and eosinophilia seen in allergic eosinophilic gastroenteritis and suggest that strategies targeting T lymphocytes may be efficacious in treatment of this disease.

Signals and nuclear factors that regulate the expression of interleukin-4 and interleukin-5 genes in helper T cells

Mouse thymoma line EL-4 cells produce cytokines such as interleukin (IL)-2, IL-3, IL-4, IL-10, and granulocyte-macrophage colony-stimulating factor in response to phorbol 12-myristate 13-acetate (PMA). EL-4 cells also produce low levels of IL-5 when stimulated by PMA alone; however, cAMP greatly augments PMA-dependent IL-5 production. A transient transfection assay revealed that two signals, PMA and cAMP, are required for optimal activation of the IL-5 promoter. In contrast, cAMP almost completely inhibited the PMA-dependent activation of the endogenous IL-2 gene, as well as the transfected IL-2 promoter. These results indicate that the IL-5 gene is positively regulated by cAMP in a manner opposite to that for the IL-2 gene. One of the nuclear factors (NFs) that regulates the response of the IL-5 promoter to cAMP and PMA has properties similar to NF for activated t cell. The P sequence of the IL-4 gene, defined as a responsive element for PMA and calcium ionophore (A23187), shares sequence similarity with the NF kappa B and the NF-activated T cell binding sites. We attempted to determine whether NF(P), a nuclear factor specific for the P sequence, is related to NF-kappa B and nuclear factor for activated T cell (NF-AT). In electromobility shift assays both NF-kappa B (P65 or P65/P50 heterodimer) and NF-AT bound to the P sequence. However, sequence specificity of NF-AT was more similar to that of NF(P), and only a small amount of P65 was detected in NF(P). These results indicate that a component or components of NF-AT have the potential to reconstitute NF(P), whereas NF-kappa B alone does not account for NF(P) in Jurkat crude extract. Taken together, these results suggest that NF-AT-like factors are involved in the regulation of IL-4 and IL-5 genes.

Glucocorticoids suppressed production and gene expression of interleukin-5 by peripheral blood mononuclear cells in atopic patients and normal subjects

BACKGROUND

Interleukin-5 (IL-5) is known to play a major role in regulating eosinophil function in atopic diseases, including bronchial asthma. Glucocorticoids are most effective agents for treating these diseases. However, their mechanism remains unclear. We examined the effects of glucocorticoids on the production and gene expression of IL-5 in atopic patients and normal subjects.

METHODS

Human peripheral blood mononuclear cells (PBMCs) in five atopic and four normal subjects were cultured with phytohemagglutinin and phorbol 12-myristate 13-acetate (PMA) in the presence of dexamethasone. IL-5 secreted by PBMCs was assayed by ELISA. Gene expression of IL-5 by PBMCs was assessed semiquantitatively by sequential reverse transcription-polymerase chain reaction, and Southern blot analysis.

RESULTS

Phytohemagglutinin/PMA-stimulated PBMCs from all atopic patients and three normal subjects secreted detectable amounts of IL-5, which were suppressed by dexamethasone in a dose-dependent manner, with 85.8% suppression at 10(-6) mol/L. Gene expression of IL-5 was detected by reverse-transcription polymerase chain reaction in PBMCs from all subjects, even when not stimulated; was increased by stimulation; and was suppressed by dexamethasone. The concentration of dexamethasone resulting in 50% inhibition in IL-5 gene expression did not differ between atopic patients and normal subjects.

CONCLUSION

These findings indicate that dexamethasone suppressed IL-5 production in atopic human PBMCs through an inhibitory action on the gene expression. These results suggest that the suppression of IL-5 production through the suppression of IL-5 gene expression is one of the most important mechanisms by which glucocorticoids inhibit eosinophil functions in the treatment of atopic diseases, including bronchial asthma.

Dietary vitamin E modulation of cytokine production by splenocytes and thymocytes from alcohol-fed mice

As vitamin E enhances immune responses, it may reduce dietary ethanol (EtOH)-induced immune suppression, thereby favorably affecting host disease resistance. The effects of dietary vitamin E at higher level in alcohol-fed female C57BL/6 mice was determined via in vitro cytokine production by splenocytes and thymocytes, and some other immune functions. A 15-fold increase of vitamin E (160 IU/liter) in a liquid diet (National Council Research), with or without EtOH (4.5%, v/v), was fed to mice for 10 weeks. Vitamin E supplementation restored production of interleukin-2, -5, -6, -10, and interferon-gamma by concanavalin A (Con A)-stimulated splenocytes and interleukin-6 and tumor necrosis factor-alpha by lipopolysaccharide-stimulated splenocytes, which were suppressed by dietary EtOH. However, it had no effect on interleukin-4 secretion, which was also reduced by splenocytes from EtOH-fed mice. Vitamin E supplementation also restored EtOH-suppressed, mitogen-induced splenocyte proliferation, but not thymocyte proliferation, although it slightly increased production of immunoglobulin A and G by lipopolysaccharide-stimulated splenocytes, which were suppressed by dietary EtOH. Dietary vitamin E, furthermore, significantly increased interleukin-2 and -6 secretion by Con A-stimulated thymocytes, which were suppressed by dietary EtOH, although it had no effect on interleukin-4 and interferon-gamma production by Con A-stimulated thymocytes from EtOH-fed mice. These data suggest that dietary vitamin E supplementation can modulate dysregulation of cytokines initiated by dietary EtOH and restore immune dysfunctions induced by EtOH ingestion.

Influence of chronic dietary ethanol on cytokine production by murine splenocytes and thymocytes

Prolonged consumption of ethanol (ETOH) results in alterations of host defense via immune modulation, increasing susceptibility to infection. In the present study, effects of chronic dietary ETOH on cytokine production by splenocytes and thymocytes, splenocyte and thymocyte proliferation induced by mitogens, splenic natural killer cell activity, and antibody production (IgA and IgG) were examined. C57BL/6 mice were fed 5% ETOH v/v in the Lieber-DeCarli liquid diet for 11 weeks. Release of interleukin (IL)-2, IL-5, IL-6, IL-10, and interferon (IFN)-gamma produced by concanavalin A (Con A) stimulated splenocytes was significantly decreased, whereas secretion of IL-4 was slightly decreased by chronic dietary ETOH compared with controls. Production of tumor necrosis factor-alpha and IL-6 by lipopolysaccharide-stimulated splenocytes was significantly and slightly decreased by ETOH compared with controls, respectively. Splenocyte and thymocyte proliferation induced by Con A was significantly inhibited by ETOH, whereas splenocyte proliferation induced by lipopolysaccharide was not affected. Natural killer cell activity was significantly inhibited by ETOH compared with controls. The production of IgA and IgG by splenocytes were also significantly decreased by ETOH compared with controls. The levels of IL-2, IL-4, and IL-6 produced by Con A-stimulated thymocytes were significantly reduced by dietary ETOH compared with control, whereas production of IFN-gamma by thymocytes was not affected. Our results suggest that chronic dietary ETOH alters the cytokine release, thereby impairing immune response and T-cell maturation, which increase host susceptibility to infection.