GATA-3 suppresses IFN-γ promoter activity independently of binding tocis-regulatory elements

Regulation of IFN-γ Expression

Interferon gamma, referred to here as IFN-γ, is a major component in immunological cell signaling and is a critical regulatory protein for overall immune system function. First discovered in 1965 (Wheelock Science 149: (3681)310-311, 1965), IFN-γ is the only Type II interferon identified. Its expression is both positively and negatively controlled by different factors. In this chapter, we will review the transcriptional and post-transcriptional control of IFN-γ expression. In the transcriptional control part, the regular activators and suppressors are summarized, we will also focus on the epigenetic control, such as chromosome access, DNA methylation, and histone acetylation. The more we learn about the control of this regulatory protein will allow us to apply this knowledge in the future to effectively manipulate IFN-γ expression for the treatment of infections, cancer, inflammation, and autoimmune diseases.

Downregulation of NFAT3 Due to Lack of T-Box Transcription Factor TBX5 Is Crucial for Cytokine Expression in T Cells

The NFAT family transcription factors play crucial roles in immunological and other biological activities. NFAT3 is rarely expressed in T cells, and the mechanisms and significance of the specific NFAT3 downregulation in T cells have been unknown. In human CD4⁺ T cells, overexpression of NFAT1 and NFAT3 enhanced and suppressed IL-2 expression, respectively. NFAT3 downregulation in Jurkat cells using RNA interference technology augmented IL-2 expression, whereas a knockdown of NFAT1, NFAT2, and NFAT4 suppressed it. The promoter/enhancer activity of the NFAT-binding site in the IL-2 gene was upregulated and downregulated by NFAT1 and NFAT3, respectively. A study employing NFAT1/NFAT3 chimeric molecules revealed that the region in NFAT3 responsible for NFAT promoter activity inhibition was located within its N-terminal transactivation domain, Ca²⁺-regulatory domain, and DNA-binding domain. Downregulation of NFAT3 expression in T cells is mediated by lower chromatin accessibility and enhancer activity in its promoter in comparison with aortic smooth muscle cells expressing endogenous NFAT3. The binding sites of T-box transcription factor TBX5 and NK-2 transcription factor-related locus 5 Nkx2.5, which were expressed at higher levels in aortic smooth muscle cells than in T cells, were located within the -387 to +97 NFAT3 promoter region, exhibiting the maximum enhancer activity. Mutating the binding site of TBX5 but not Nkx2.5 diminished the NFAT3 promoter activity, whereas the overexpression of TBX5 enhanced it. Introduction of TBX5 into CD4⁺ T cells enhanced the expression of NFAT3 and suppressed that of IL-2. TBX5 deficiency-mediated downregulation of NFAT3 is crucial for the high cytokine-producing activity of T cells.

Molecular characterization and expression analysis of interferon-gamma in black seabream Acanthopagrus schlegelii

Interferon gamma (IFN-γ) is a major component in immunological signaling and plays a key role in resisting viral infection. In this study, we identified and characterized an IFN-γ gene (AsIFN-γ) in the marine fish black seabream (Acanthopagrus schlegelii). We cloned AsIFN-γ genomic sequence, which comprises four exons, three introns and an upstream promoter including several conserved regulatory elements. The complete cDNA of AsIFN-γ was 816 bp in length and encoded a putative 194 amino acids (aa) protein with a 22 aa signal peptide, six α-helices and one nuclear localization signal (NLS). Multiple alignment showed that AsIFN-γ protein shared 31-60% identity with IFN-γ of other fish but low identity with fish IFN-γrel and IFN-γ of other vertebrates. AsIFN-γ was constitutively expressed in all examined tissues with the highest expression level in immune organs, such as spleen, gill and kidney. In black seabream infected by red spotted nervous necrosis virus (RGNNV), the expression of AsIFN-γ was significantly up-regulated in most tissues, and RGNNV infection in vitro also induced significant up-regulation of AsIFN-γ, indicating that AsIFN-γ was involved in immune response to RGNNV infection. Overexpression of AsIFN-γ in cultured Acanthopagrus schlegelii brain (AsB) cells rapidly and transiently stimulated the expression of JAK-STAT signaling pathway related genes including STAT1, STAT2 and IRF9, as well as the downstream antiviral genes MX1 and ISG15. Furthermore, overexpression of AsIFN-γ was able to significantly inhibit RGNNV replication and virus production in AsB cells. In summary, we identified a conserved IFN-γ gene of black seabream, and demonstrated the rapid and strong antiviral activities of AsIFN-γ against RGNNV in black seabream.

Distinct characteristics of nasal polyps with and without eosinophilia

Introduction

Eosinophilic and noneosinophilic Nasal polyps (NPs) are different subtypes of NPs and require different treatment methods.

Objective

To compare the histologic characteristics, mRNA and protein expression between Nasal Polyps with and without eosinophilia.

Methods

NPs tissues were obtained from eighty-six NPs patients during surgery. Eosinophilic and noneosinophilic NPs were distinguished according to immunochemical results of the specimen. The histological, mRNA and protein expression features were compared between the two groups.

Results

In eosinophilic NPs, we observed a significantly higher GATA-3, IL-5, IL-4, IL-13 mRNA and protein expression. In noneosinophilic NPs, IL-17, IL-23 and RORc mRNA and protein expression were increased. Immunohistochemistry tests showed, more mast cells and less neutrophils in eosinophilic NPs compared with noneosinophilic NPs. Eosinophilic NPs patient presented more severe symptom scores when compared to noneosinophilic NPs.

Conclusion

We demonstrate for the first time that Th2 is the predominant reaction in eosinophilic NPs while Th17 is the predominant reaction in noneosinophilic NPs. Our study may provide new treatment strategy for NPs.

Susceptibility to Salmonella carrier-state: a possible Th2 response in susceptible chicks

Infection of chicken with Salmonella may lead to a carrier-state characterized by the persistence of bacteria in the ceca for a long period of time and result in their excretion in feces. This excretion is the source of contamination of their congeners and food. During infection, enterocytes are the primary target cells for Salmonella, the producers of soluble factors which launch immune response and cells which are reciprocally responsive to surrounding immune cells. This study used microarrays to compare the gene expression profile during carrier-state of enterocytes purified from infected and control chicks which are either resistant or susceptible to Salmonella Enteritidis carrier-state. In total, we identified 271 genes significantly differentially expressed with an absolute fold change greater than 1.5. A global analysis determined interaction networks between differentially regulated genes. Using an a priori approach, our analyses focused on differentially expressed genes which were transcriptionally linked to cytokines playing a major role in the fate of the immune response. The expression of genes transcriptionally linked to type I interferon and TGF-β was down-regulated in infected chicks from both lines. Gene expression linked to the Th1 axis suggests the latter is inhibited in both lines. Finally, the expression of genes linked to IL-4, IL-5 and IL-13 indicates that susceptibility to carrier-state could be associated with a Th2 bias. Overall, these results highlight that the response to Salmonella during the acute phase and carrier-state is different and that enterocytes play a central role in this response.

Impairment of host defense against disseminated candidiasis in mice overexpressing GATA-3

Candida species are the most common source of nosocomial invasive fungal infections. Previous studies have indicated that T-helper immune response is the critical host factor for susceptibility to Candida infection. The transcription factor GATA-3 is known as the master regulator for T-helper type 2 (Th2) differentiation. We therefore investigated the role of GATA-3 in the host defense against systemic Candida infection using GATA-3-overexpressing transgenic mice. The survival of GATA-3-overexpressing mice after Candida infection was significantly lower than that of wild-type mice. Candida outgrowth was significantly increased in the kidneys of GATA-3-overexpressing mice, compared with wild-type mice. The levels of various Th2 cytokines, including interleukin-4 (IL-4), IL-5, and IL-13, were significantly higher while the level of Th1 cytokine gamma interferon was significantly lower in the splenocytes of GATA-3-overexpressing mice after Candida infection. Recruitment of macrophages into the peritoneal cavity in response to Candida infection and their phagocytic activity were significantly lower in GATA-3-overexpressing mice than in wild-type mice. Exogenous administration of gamma interferon to GATA-3-overexpressing mice significantly reduced Candida outgrowth in the kidney and thus increased the survival rate. Administration of gamma interferon also increased the recruitment of macrophages into the peritoneal cavity in response to Candida infection. These results indicate that overexpression of GATA-3 modulates macrophage antifungal activity and thus enhances the susceptibility to systemic Candida infection, possibly by reducing the production of gamma interferon in response to Candida infection.

Ikaros silences T-bet expression and interferon-gamma production during T helper 2 differentiation

CD4+ T cells can be instructed by nonantigen-specific signals to differentiate into functionally distinct lineages with mutually exclusive patterns of cytokine production. The molecular events that drive interferon-gamma (IFN gamma) production during Th1 development are well understood, but mechanisms that silence this cytokine during Th2 polarization are not clear. In this study, we find that the tbx21 gene encoding the Th1 master regulator T-bet is a direct target of the transcriptional repressor Ikaros. In Th2 cells, which do not express T-bet, strong Ikaros binding could be detected at the endogenous tbx21 promoter, whereas this gene was not occupied by Ikaros in T-bet-expressing Th1 cells. Inhibition of Ikaros DNA binding activity during Th2 polarization resulted in loss of Ikaros promoter occupancy, increased T-bet expression, and inappropriate T-bet-dependent production of IFN gamma. Ikaros was also required for epigenetic imprinting of the ifn gamma locus during Th2 polarization, and loss of Ikaros function in vivo led to an inappropriate Th1 response to the parasite Shistosoma mansoni. These studies demonstrate that Ikaros, a factor with an established role in lymphocyte development, also regulates the development of peripheral T helper responses.

T-box 21 transcription factor is responsible for distorted T(H)2 differentiation in human peripheral CD4+ T cells

BACKGROUND

Regardless of T(H)1/T(H)2 theory, CD4(+) T cells of patients with allergic asthma, a typical T(H)2 disease, and those of healthy subjects expressed equivalent levels of IFN-gamma, even though T(H)2 cytokines were significantly upregulated in asthmatic patients.

OBJECTIVE

The mechanisms underlying distorted T(H)2 cell polarization in human T cells were elucidated.

METHODS

Cytokine-producing activity and the expression of T(H)1/T(H)2-specific transcription factors in naïve, T(H)1/T(H)2, or both CD4(+) T cells derived from human peripheral and cord blood were comparatively analyzed. The mechanisms of the differential expression of T-box 21 transcription factor (T-bet) in the cells were assessed by determining the chromatin accessibility at the TBX21 gene. The functional roles of T-bet and other transcription factors in human T(H)1/T(H)2 differentiation were further investigated.

RESULTS

T(H)2 cells derived from naive CD4(+) T cells in peripheral blood but not in cord blood produced IFN-gamma. T-bet was expressed in peripheral, but not cord blood, resting naive T cells. Consistently, the accessibility at the proximal TBX21 gene promoter in peripheral naive T cells was higher than that in cord blood naive T cells. IFN-gamma-producing activity was induced in T(H)2-differentiated cord blood T cells by means of ectopic expression of T-bet. In addition, a reduction of T-bet in peripheral T cells suppressed IFN-gamma production. T-bet not only upregulated IFN-gamma but also downregulated IL-4 and IL-13 gene transcription, independently of the modification of T(H)1/T(H)2 balance.

CONCLUSION

The expression of T-bet at a naive stage is crucial for the development of IFN-gamma-producing T cells in human peripheral blood, even in T(H)2-related diseases.

At the crossroads of T helper lineage commitment-Epigenetics points the way

The immune system has the capacity to respond to various types of pathogens including bacteria, viruses, tumors and parasites. This requires a flexible immune system, which in part depends on the development of alternative effector T helper cells, with different cytokine repertoires that direct the overall immune response. The reciprocal effects of the T helper subtypes Th1 and Th2 are well documented, but the mechanisms involved in alternative cytokine expression and silencing are less well defined. Introduction of advances within the field of chromatin folding and epigenetic regulation of transcription has begun to explain some of the fundamental principles of T helper cell development. In addition, epigenetic regulation has proven essential also for the more recently discovered T helper cell subtypes; regulatory T cells and the Th17 lineage. As the importance of proper epigenetic regulation becomes evident, attention is also focused on the potential harmfulness of epigenetic dysregulation. Autoimmunity and allergy are two clinical situations that have been implicated as results of imperfect cytokine silencing. This review will address recent advances in the field of epigenetic regulation of T lymphocytes and their maturation from naive cells into different effector T cell lineages. In particular, epigenetic involvement in regulation of key effector cytokines and specific transcription factors determining the CD4(+) T lymphocyte lineage commitment will be discussed.

Gfi1-mediated stabilization of GATA3 protein is required for Th2 cell differentiation

The differentiation of naive CD4 T cells into Th2 cells requires the T cell receptor-mediated activation of the ERK MAPK cascade. Little is known, however, in regard to how the ERK MAPK cascade regulates Th2 cell differentiation. We herein identified Gfi1 (growth factor independent-1) as a downstream target of the ERK MAPK cascade for Th2 cell differentiation. In the absence of Gfi1, interleukin-5 production and the change of histone modification at the interleukin-5 gene locus were severely impaired. Furthermore, the interferon gamma gene showed a striking activation in the Gfi1(-/-) Th2 cells. An enhanced ubiquitin/proteasome-dependent degradation of GATA3 protein was observed in Gfi1(-/-) Th2 cells, and the overexpression of GATA3 eliminated the defect of Th2 cell function in Gfi1-deficient Th2 cells. These data suggest that the T cell receptor-mediated induction of Gfi1 controls Th2 cell differentiation through the regulation of GATA3 protein stability.

T-cell regulation in chronic paranasal sinus disease

BACKGROUND

Chronic rhinosinusitis is an inflammatory disease with distinct cytokine and remodeling patterns. Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by a T(H)2-skewed eosinophilic inflammation, whereas chronic rhinosinusitis without nasal polyps (CRSsNP) represents a predominant T(H)1 milieu.

OBJECTIVE

We aimed to study the direct tissue expression of transcription factors for T-cell subpopulations, including T regulatory cells, in relation to the cytokine expression patterns in the different disease subgroups.

METHODS

The expression of forkhead box P3 (FOXP3), T-box transcription factor (T-bet), GATA-3, retinoid acid-related orphan receptor C (RORc), the suppressive cytokines TGF-beta1 and IL-10, and T(H)1/ T(H)2/ T(H)17 cytokines (IFN-gamma, IL-4, IL-5, IL-13, IL-17) were analyzed by means of RT-PCR in 13 CRSsNP, 16 CRSwNP, and 10 control samples. Additional protein measurements were performed for TGF-beta1 and IFN-gamma.

RESULTS

In CRSwNP, we observed a significantly lower FOXP3 mRNA and TGF-beta1 protein expression, but a significantly higher T-bet, GATA-3, IL-5, and IL-13 mRNA expression compared with controls, whereas RORc was not significantly different compared with controls. In CRSsNP, FOXP3, T-bet, GATA-3, and RORc expression was not significantly different from controls, whereas TGF-beta1 mRNA, IFN-gamma mRNA, and protein were significantly higher in CRSsNP compared with controls. For IL-17, no significant differences were noted among all groups.

CONCLUSION

We demonstrate for the first time a decreased FOXP3 expression accompanied by an upregulation of T-bet and GATA-3 and a downregulation of TGF-beta1 in CRSwNP versus controls and CRSsNP.

Downregulation of IL-13 gene transcription by T-bet in human T cells

BACKGROUND

Downregulation of a Th2 cytokine, IL-4, by a Th1-specific transcription factor, T-bet, has been demonstrated. However, the regulatory role of T-bet in another Th2 cytokine, IL-13, is not fully delineated.

METHODS

IL-13 mRNA expression in Jurkat cells was examined by quantitative RT-PCR, while the transcriptional activity of 5'-flanking region in the IL-13 gene encompassing -1077 to +49 was investigated by fluorescence-based promoter reporter assay. The effect of T-bet was investigated by transfection of the cells with the T-bet expression vector.

RESULTS

Stimulation with phorbol ester plus Ca2+ ionophore clearly induced IL-13 gene transcription in Jurkat cells. Ectopically expressed T-bet significantly suppressed the inducible mRNA expression and promoter activity of IL-13.

CONCLUSION

IL-13 expression was downregulated by T-bet at the level of gene transcription, independently of the modulation of Th1/Th2 balance. T-bet is the potential key factor in the development of Th1/Th2-related diseases.

Differential contribution of NFATc2 and NFATc1 to TNF-alpha gene expression in T cells

The NFAT family transcription factors play crucial roles in immunological and other biological events; however, the functional differences among NFAT members have not been fully elucidated. This study investigated the relative contribution of NFATc2 and NFATc1 to the transactivation of cytokine genes in T cells. Ectopic expression of NFATc2 but not NFATc1, especially its short isoform, enhanced TNF-alpha synthesis in human T cells at the gene transcription level, whereas both NFATs augmented IL-2 expression. In addition, a reduction of the shortest NFATc1 isoform using RNA interference technology failed to suppress TNF-alpha expression. The promoter/enhancer activity of the NFAT-binding site in the TNF-alpha gene was up-regulated by NFATc2 but not by NFATc1, whereas both NFATs associated similarly with this region. A study of mRNA expression using NFATc2/NFATc1 chimeric molecules revealed that the enhancing activity of NFAT on the TNF-alpha gene was lost by truncation of its C-terminal transactivation domain. In addition, this domain derived from NFATc2 behaved as a dominant negative against the NFAT site in TNF-alpha promoter-dependent transcriptional activity in T cells. We conclude that the C-terminal transactivation domain in NFAT is crucial for TNF-alpha gene expression in human T cells.

Regulation of interferon-gamma during innate and adaptive immune responses

Interferon-gamma (IFN-gamma) is crucial for immunity against intracellular pathogens and for tumor control. However, aberrant IFN-gamma expression has been associated with a number of autoinflammatory and autoimmune diseases. This cytokine is produced predominantly by natural killer (NK) and natural killer T (NKT) cells as part of the innate immune response, and by Th1 CD4 and CD8 cytotoxic T lymphocyte (CTL) effector T cells once antigen-specific immunity develops. Herein, we briefly review the functions of IFN-gamma, the cells that produce it, the cell extrinsic signals that induce its production and influence the differentiation of naïve T cells into IFN-gamma-producing effector T cells, and the signaling pathways and transcription factors that facilitate, induce, or repress production of this cytokine. We then review and discuss recent insights regarding the molecular regulation of IFN-gamma, focusing on work that has led to the identification and characterization of distal regulatory elements and epigenetic modifications with the IFN-gamma locus (Ifng) that govern its expression. The epigenetic modifications and three-dimensional structure of the Ifng locus in naive CD4 T cells, and the modifications they undergo as these cells differentiate into effector T cells, suggest a model whereby the chromatin architecture of Ifng is poised to facilitate either rapid opening or silencing during Th1 or Th2 differentiation, respectively.

Correlation between mRNA expression of Th1/Th2 cytokines and their specific transcription factors in human helper T-cell clones

The mechanisms that underlie Th1/Th2 differentiation of human T cells are incompletely defined. In the present study, a panel of human T-cell clones was used to elucidate the relationship between Th1/Th2-specific transcription factors and cytokine production in human helper T cells. The mRNA expression level of T-bet, a Th1-specific transcription factor, was higher in Th1 clones than in Th2 clones. In contrast, inducible expression of Th2-specific transcription factors (GATA-3 and c-Maf) in Th2 clones was higher than that in Th1 clones. The expression level of T-bet in various T-cell clones was positively correlated with that of IFN-gamma and negatively correlated with that of Th2 cytokines, particularly IL-4. Interestingly, the expression of IL-3 and IL-13, but not of other Th2 cytokines IL-4 and IL-5, was strongly correlated with GATA-3 mRNA levels. A reduction of GATA-3 using RNA interference technology suppressed, whereas overexpression of GATA-3 enhanced, the expression of IL-3 and IL-13. In conclusion, the level of T-bet expression is correlated with Th1/Th2 polarization status, whereas GATA-3 is a crucial factor in determining the IL-3 and IL-13 producing capacity of human T cells.

An insight into molecular mechanisms of human T helper cell differentiation

Selective activation of T helper (Th) cell subsets plays an important role in immune response to pathogens as well as in the pathogenesis of human allergy and inflammatory diseases. Th1 cells along with the recently discovered Th17 cells play a role in the pathogenesis of autoimmune diseases. Th2 cytokines lead to series of inflammatory processes characteristic for asthma and other atopic diseases. To understand the pathogenesis of immune-mediated diseases it is crucial to dissect pathways and regulatory networks leading to the development of distinct Th subsets. Such knowledge may lead to better strategies for developing diagnostics and therapies for these diseases. The differentiation of Th1, Th2, and Th17 effector cells is driven by signals originating from T cell and costimulatory receptors as well as cytokines in the surroundings of activated naive T helper cells. There are several proteins involved in the regulation of this differentiation process. Most of the data on T helper cell differentiation have been acquired using mouse. In this review, we have summarized what is known about human T helper differentiation. In addition, selected differences between human and mouse will be discussed.

IL-4 Gene Transcription in Human T Cells Is Suppressed by T-Bet

T-bet is crucially implicated in Th1 differentiation due to its strong promoting activity for IFN-gamma gene transcription. However, the regulatory role of T-bet in Th2 cytokines is not fully delineated.

METHODS

The effect of T-bet on mRNA expression as well as the promoter activity of IL-4 in human T cells was investigated by employing quantitative RT-PCR and fluorescence-based promoter reporter assay procedures.

RESULTS

IL-4 mRNA expression as well as the transcriptional activity of 5'-flanking region in the IL-4 gene encompassing -1105 to +4 in Jurkat cells was clearly upregulated upon stimulation. The inducible mRNA expression and the promoter activity of IL-4 were significantly diminished by ectopic expression of T-bet.

CONCLUSION

IL-4 gene transcription is inhibited by T-bet via the suppression of its promoter activity, independently of IFN-gamma. T-bet facilitates Th1 differentiation through not only upregulation of IFN-gamma, but also downregulation of IL-4 gene transcription.

Overexpression of the transcription factor GATA-3 enhances the development of pulmonary fibrosis

Recent studies have demonstrated that Th2 cytokines, such as interleukin-4 and interleukin-13, enhance fibrotic processes by activating fibroblast proliferation and collagen production, whereas interferon-gamma, a Th1 cytokine, inhibits these processes. Th1 and Th2 cells both differentiate from common T precursor cells, with transcription factor GATA-3 a key regulator of Th2 differentiation. In the present study, therefore, we examined the effects of GATA-3 overexpression on the development of pulmonary fibrosis in a mouse model. Wild-type C57BL/6 mice and GATA-3-overexpressing (GATA-3-tg) mice of the same background were intratracheally treated with bleomycin. The survival rate after bleomycin was significantly decreased in GATA-3-tg mice compared with wild-type mice. The degree of pulmonary fibrosis was much greater in GATA-3-tg mice than in wild-type mice 28 days after bleomycin treatment. Lung interferon-gamma concentration was significantly decreased in GATA-3-tg mice compared with wild-type mice by 7 days after either saline or bleomycin treatment. The concentration of transforming growth factor-beta, a fibrogenic cytokine, was significantly higher in GATA-3-tg mice than in wild-type mice. Exogenous administration of interferon-gamma to GATA-3-tg mice improved the degree of pulmonary fibrosis and thus increased survival. These results indicate that overexpression of GATA-3 enhances the development of pulmonary fibrosis, possibly by reducing interferon-gamma levels in the lung.

Unraveling the Pros and Cons of Interferon-γ Gene Regulation

Although transforming growth factor-beta (TGF-beta) inhibition of interferon-gamma (IFN-gamma) expression has been known for some time, in this issue of Immunity, the crosstalk between proinflammatory cytokine and TGF-beta signaling that regulates IFN-gamma expression is detailed for the first time.

Association of the -183 polymorphism in the IFN-gamma gene promoter with hepatitis B virus infection in the Chinese population

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that plays an important role in regulating cellular immune responses. Regulation of IFN-gamma expression is considered to be strictly controlled at the transcriptional level. Two single-nucleotide polymorphisms (SNPs) within the human IFN-gamma promoter (at positions -183 and -155) are considered to influence the promoter activity by altering the acting transcription factor-1 (AP-1) binding. We sought to assess the association between the SNPs of the IFN-gamma promoter and the host susceptibility to hepatitis B virus (HBV) infection, as well as its interaction with age and gender. No polymorphism at position-155 was detected in any of the participants, but a significant difference was found in the polymorphism at position -183 between the cases and controls (G/T and T/T vs. GG; P < 0.01, odds ratio (OR) = 4.50 (95% confidence interval (CI) = 2.23-9.09). A susceptibility analysis revealed a gradually increased trend of the OR value from the young to the old group (OR = 3.03, 4.17, and 5.56). Similarly, the association of the -183 polymorphism was markedly different in females (OR = 5.71). Our data suggest that the polymorphism at position -183 of the IFN-gamma gene promoter may be associated with susceptibility to HBV infection, and age and gender factors are coordinative risk factors.

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.