GATA-3 represses gp91phox gene expression in eosinophil-committed HL-60-C15 cells

Effects of Helicobacter pylori on the expression levels of GATA-3 and connexin 32 and the GJIC function in gastric epithelial cells and their association by promoter analysis

The present study aimed to explore the effects of Helicobacter pylori (H. pylori) infection on the expression of transcription factor GATA binding protein 3 (GATA-3) and connexin 32 (Cx32) in cultured gastric mucosa cells, and their association with each other. GES-1 cells were co-cultured with East Asian type cytotoxin-associated gene A⁺ H. pylori in the H. pylori group, and without H. pylori culture in the control group. Additionally, Mongolian gerbils were gavaged with H. pylori, and later the gastric antrum tissues were collected. The GATA-3 and Cx32 mRNA and protein expression levels were detected by a reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. The scratch labeling fluorescent dye tracer (SLDT) technique was used to detect the gap junctional intercellular communication (GJIC) function. GATA-3 small interfering RNA (siRNA) was transfected into BGC823 cells and its effect on Cx32 expression levels was detected. The impact of GATA-3 on Cx32 promoter transcriptional activity was detected using a dual luciferase reporter assay. The results revealed that H. pylori infection increased GATA-3 expression and decreased Cx32 expression in GES-1 cells and in animal gastric tissues compared with their respective controls, whilst in BGC823 cells, GATA-3 siRNA increased Cx32 expression compared with the control. In the SLDT experiment of GES-1 cells with H. pylori infection, the fluorescent dye was primarily limited to a single cell row close to the scratch, and only a limited amount of dye passing to the second cell row, indicating that the GJIC function was substantially reduced or absent compared with the control group, where the fluorescence dye transferred to the neighboring cells of 3–4 rows, indicating a stronger GJIC function comparatively. GATA-3 inhibited the expression of the luciferase reporter gene, compared with the controls, suggesting that GATA-3 inhibited the expression of Cx32 by binding to Cx32 promoter sites. These results indicated that H. pylori-increased GATA-3 expression, which downregulated Cx32 expression, may serve an important function in gastric carcinogenesis, and GATA-3 siRNA may serve a function in the prevention and treatment of gastric cancer.

NOX Modifiers-Just a Step Away from Application in the Therapy of Airway Inflammation?

SIGNIFICANCE

NADPH oxidase (NOX) enzymes, which are widely expressed in different airway cell types, not only contribute to the maintenance of physiological processes in the airways but also participate in the pathogenesis of many acute and chronic diseases. Therefore, the understanding of NOX isoform regulation, expression, and the manner of their potent inhibition might lead to effective therapeutic approaches.

RECENT ADVANCES

The study of the role of NADPH oxidases family in airway physiology and pathophysiology should be considered as a work in progress. While key questions still remain unresolved, there is significant progress in terms of our understanding of NOX importance in airway diseases as well as a more efficient way of using NOX modifiers in human settings.

CRITICAL ISSUES

Agents that modify the activity of NADPH enzyme components would be considered useful tools in the treatment of various airway diseases. Nevertheless, profound knowledge of airway pathology, as well as the mechanisms of NOX regulation is needed to develop potent but safe NOX modifiers.

FUTURE DIRECTIONS

Many compounds seem to be promising candidates for development into useful therapeutic agents, but their clinical potential is yet to be demonstrated. Further analysis of basic mechanisms in human settings, high-throughput compound scanning, clinical trials with new and existing molecules, and the development of new drug delivery approaches are the main directions of future studies on NOX modifiers. In this article, we discuss the current knowledge with regard to NOX isoform expression and regulation in airway inflammatory diseases as well as the aptitudes and therapeutic potential of NOX modifiers.

Allergen-induced asthmatic responses modified by a GATA3-specific DNAzyme

BACKGROUND

The most prevalent phenotype of asthma is characterized by eosinophil-dominated inflammation that is driven by a type 2 helper T cell (Th2). Therapeutic targeting of GATA3, an important transcription factor of the Th2 pathway, may be beneficial. We evaluated the safety and efficacy of SB010, a novel DNA enzyme (DNAzyme) that is able to cleave and inactivate GATA3 messenger RNA (mRNA).

METHODS

We conducted a randomized, double-blind, placebo-controlled, multicenter clinical trial of SB010 involving patients who had allergic asthma with sputum eosinophilia and who also had biphasic early and late asthmatic responses after laboratory-based allergen provocation. A total of 40 patients could be evaluated; 21 were assigned to receive 10 mg of SB010, and 19 were assigned to receive placebo, with each study drug administered by means of inhalation once daily for 28 days. An allergen challenge was performed before and after the 28-day period. The primary end point was the late asthmatic response as quantified by the change in the area under the curve (AUC) for forced expiratory volume in 1 second (FEV1).

RESULTS

After 28 days, SB010 attenuated the mean late asthmatic response by 34%, as compared with the baseline response, according to the AUC for FEV1, whereas placebo was associated with a 1% increase in the AUC for FEV1 (P=0.02). The early asthmatic response with SB010 was attenuated by 11% as measured by the AUC for FEV1, whereas the early response with placebo was increased by 10% (P=0.03). Inhibition of the late asthmatic response by SB010 was associated with attenuation of allergen-induced sputum eosinophilia and with lower levels of tryptase in sputum and lower plasma levels of interleukin-5. Allergen-induced levels of fractional exhaled nitric oxide and airway hyperresponsiveness to methacholine were not affected by either SB010 or placebo.

CONCLUSIONS

Treatment with SB010 significantly attenuated both late and early asthmatic responses after allergen provocation in patients with allergic asthma. Biomarker analysis showed an attenuation of Th2-regulated inflammatory responses. (Funded by Sterna Biologicals and the German Federal Ministry of Education and Research; ClinicalTrials.gov number, NCT01743768.).

Functionally competent eosinophils differentiated ex vivo in high purity from normal mouse bone marrow

We have devised an ex vivo culture system which generates large numbers of eosinophils at high purity (>90%) from unselected mouse bone marrow progenitors. In response to 4 days of culture with recombinant mouse FLT3-L and recombinant mouse stem cell factor followed by recombinant mouse IL-5 alone thereafter, the resulting bone marrow-derived eosinophils (bmEos) express immunoreactive major basic protein, Siglec F, IL-5R alpha-chain, and transcripts encoding mouse eosinophil peroxidase, CCR3, the IL-3/IL-5/GM-CSF receptor common beta-chain, and the transcription factor GATA-1. BmEos are functionally competent: they undergo chemotaxis toward mouse eotaxin-1 and produce characteristic cytokines, including IFN-gamma, IL-4, MIP-1alpha, and IL-6. The rodent pathogen pneumonia virus of mice replicates in bmEos and elevated levels of IL-6 are detected in supernatants of bmEos cultures in response to active infection. Finally, differentiating bmEos are readily transfected with lentiviral vectors, suggesting a means for rapid production of genetically manipulated cells.

GATA3-driven Th2 responses inhibit TGF-beta1-induced FOXP3 expression and the formation of regulatory T cells

Transcription factors act in concert to induce lineage commitment towards Th1, Th2, or T regulatory (T_reg) cells, and their counter-regulatory mechanisms were shown to be critical for polarization between Th1 and Th2 phenotypes. FOXP3 is an essential transcription factor for natural, thymus-derived (nT_reg) and inducible T_reg (iT_reg) commitment; however, the mechanisms regulating its expression are as yet unknown. We describe a mechanism controlling iT_reg polarization, which is overruled by the Th2 differentiation pathway. We demonstrated that interleukin 4 (IL-4) present at the time of T cell priming inhibits FOXP3. This inhibitory mechanism was also confirmed in Th2 cells and in T cells of transgenic mice overexpressing GATA-3 in T cells, which are shown to be deficient in transforming growth factor (TGF)-β–mediated FOXP3 induction. This inhibition is mediated by direct binding of GATA3 to the FOXP3 promoter, which represses its transactivation process. Therefore, this study provides a new understanding of tolerance development, controlled by a type 2 immune response. IL-4 treatment in mice reduces iT_reg cell frequency, highlighting that therapeutic approaches that target IL-4 or GATA3 might provide new preventive strategies facilitating tolerance induction particularly in Th2-mediated diseases, such as allergy.

Specific immune responses against foreign or autologous antigens are driven by specialized epitope-specific T cells, whose numbers expand upon recognition of antigen found on professional antigen-presenting cells. The subsequent maturation process involves the differentiation of certain T cell phenotypes such as pro-inflammatory cells (Th1, Th2, Th17) or regulatory T (T_reg) cells, which serve to keep the immune response in check. The current study focuses on the role of two key transcription factors—FOXP3 and GATA3—in controlling the commitment of these cells. We demonstrate that the Th2 cytokine IL-4 inhibits the induction of FOXP3 and thus inhibits the generation of inducible T_reg cells. We show that IL-4–induced GATA3 mediates FOXP3 inhibition by directly binding to a GATA element in the FOXP3 promoter. We hypothesize that therapeutic agents aimed at neutralizing IL-4 could be a novel strategy to facilitate inducible T_reg cell generation and thus promotion of tolerance in allergies and other Th2-dominated diseases.

It is shown that Th2 responses prevent the generation of inducible T_regs. This is mediated by IL-4 induction of GATA3, which binds directly to and represses the FOXP3 promoter. This mechanism is likely to be relevant in the induction of immunotolerance, particularly in allergic diseases.

Transcription factor network downstream of protease activated receptors (PARs) modulating mouse bladder inflammation

BACKGROUND

All four PARs are present in the urinary bladder, and their expression is altered during inflammation. In order to search for therapeutic targets other than the receptors themselves, we set forth to determine TFs downstream of PAR activation in the C57BL/6 urinary bladders.

METHODS

For this purpose, we used a protein/DNA combo array containing 345 different TF consensus sequences. Next, the TF selected was validated by EMSA and IHC. As mast cells seem to play a fundamental role in bladder inflammation, we determined whether c-kit receptor deficient (Kit w/Kit w-v) mice have an abrogated response to PAR stimulation. Finally, TFEB antibody was used for CHIP/Q-PCR assay and revealed up-regulation of genes known to be downstream of TFEB.

RESULTS

TFEB, a member of the MiTF family of basic helix-loop-helix leucine zipper, was the only TF commonly up-regulated by all PAR-APs. IHC results confirm a correlation between inflammation and TFEB expression in C57BL/6 mice. In contrast, Kit w/Kit w-v mice did not exhibit inflammation in response to PAR activation. EMSA results confirmed the increased TFEB binding activity in C57BL/6 but not in Kit w/Kit w-v mice.

CONCLUSION

This is the first report describing the increased expression of TFEB in bladder inflammation in response to PAR activation. As TFEB belongs to a family of TFs essential for mast cell survival, our findings suggest that this molecule may influence the participation of mast cells in PAR-mediated inflammation and that targeting TFEB/MiTF activity may be a novel approach for the treatment of bladder inflammatory disorders.

Structure and regulation of the neutrophil respiratory burst oxidase: comparison with nonphagocyte oxidases

Neutrophils play an essential role in the body's innate defense against pathogens and are one of the primary mediators of the inflammatory response. To defend the host, neutrophils use a wide range of microbicidal products, such as oxidants, microbicidal peptides, and lytic enzymes. The generation of microbicidal oxidants by neutrophils results from the activation of a multiprotein enzyme complex known as the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which is responsible for transferring electrons from NADPH to O2, resulting in the formation of superoxide anion. During oxidase activation, cytosolic oxidase proteins translocate to the phagosome or plasma membrane, where they assemble around a central membrane-bound component known as flavocytochrome b. This process is highly regulated, involving phosphorylation, translocation, and multiple conformational changes. Originally, it was thought that the NADPH oxidase was restricted to phagocytes and used solely in host defense. However, recent studies indicate that similar NADPH oxidase systems are present in a wide variety of nonphagocytic cells. Although the nature of these nonphagocyte NADPH oxidases is still being defined, it is clear that they are functionally distinct from the phagocyte oxidases. It should be noted, however, that structural features of many nonphagocyte oxidase proteins do seem to be similar to those of their phagocyte counterparts. In this review, key structural and functional features of the neutrophil NADPH oxidase and its protein components are described, including a consideration of transcriptional and post-translational regulatory features. Furthermore, relevant details about structural and functional features of various nonphagocyte oxidase proteins will be included for comparison.

Cooperation of STAT-1 and IRF-1 in interferon-gamma-induced transcription of the gp91(phox) gene

Interferon (IFN)-gamma induces the expression of the gp91(phox) gene both during myeloid differentiation and also in mature phagocytes through several cis-elements and their binding proteins. To find new cis-elements for this induction, transient expression assays were performed using a reporter gene driven by serially truncated gp91(phox) promoters in U937 cells. The results suggest that a critical cis-element for induction exists in the region from bp -115 to -96 of the promoter. Site-directed mutagenesis showed that a gamma-activated sequence (GAS) element at bp -100 (-100GAS) of the gp91(phox) promoter plays a pivotal role for the IFN-gamma-dependent activity of the bp -115 to +12 region of the gp91(phox) promoter. Electrophoretic mobility shift assays using several GAS competitors and specific antibodies indicated that phosphorylated STAT-1alpha specifically binds to the -100GAS. Site-directed mutagenesis showed that an interferon-stimulated response element (ISRE) at bp -88 (-88ISRE) mediates the induction of the gene by IFN-gamma in cooperation with -100GAS. Electrophoretic mobility shift assay showed that IRF-1 dominantly binds to -88ISRE in an IFN-gamma-dependent fashion. These results demonstrate a new mechanism for IFN-gamma-induced transcription of the gp91(phox) gene by the cooperation of STAT-1alpha and IRF-1 binding to -100GAS and -88ISRE, respectively.

Ragweed-induced expression of GATA-3, IL-4, and IL-5 by eosinophils in the lungs of allergic C57BL/6J mice

Allergen-induced recruitment of T lymphocytes and eosinophils to the airways is associated with increased expression of the transcription factor GATA-3. In this study, the relationship between airway inflammation and GATA-3 expression in the lungs was investigated using ragweed-sensitized C57BL/6J mice. Intratracheal ragweed challenge increased both the number of GATA-3-expressing cells in the perivascular and peribronchial regions and the amount of expression per cell. Interleukin (IL)-4 and IL-5 levels in bronchoalveolar lavage fluid were upregulated in parallel with GATA-3 expression. GATA-3 mRNA and protein colocalized to eosinophils. Eosinophils isolated from the lungs and stimulated with phorbol 12-myristate 13-acetate and/or A-23187 released IL-5. The release was inhibited by actinomycin D, which indicates that de novo synthesis of the cytokine was involved. Western blot analysis of proteins from isolated eosinophils demonstrated expression of the p50 subunit of nuclear factor-kappaB, a transcription factor that is implicated in control of GATA-3 expression. These data provide evidence that allergen challenge increases GATA-3 and proinflammatory cytokine expression by pulmonary eosinophils, which could provide positive feedback for the inflammatory response.

Genetic, biochemical, and clinical features of chronic granulomatous disease

The reduced nicotinamide dinucleotide phosphate (NADPH) oxidase complex allows phagocytes to rapidly convert O2 to superoxide anion which then generates other antimicrobial reactive oxygen intermediates, such as H2O2, hydroxyl anion, and peroxynitrite anion. Chronic granulomatous disease (CGD) results from a defect in any of the 4 subunits of the NADPH oxidase and is characterized by recurrent life-threatening bacterial and fungal infections and abnormal tissue granuloma formation. Activation of the NADPH oxidase requires translocation of the cytosolic subunits p47phox (phagocyte oxidase), p67phox, and the low molecular weight GT-Pase Rac, to the membrane-bound flavocytochrome, a heterodimer composed of the heavy chain gp91phox and the light chain p22phox. This complex transfers electrons from NADPH on the cytoplasmic side to O2 on the vacuolar or extracellular side, thereby generating superoxide anion. Activation of the NADPH oxidase requires complex rearrangements between the protein subunits, which are in part mediated by noncovalent binding between src-homology 3 domains (SH3 domains) and proline-rich motifs. Outpatient management of CGD patients relies on the use of prophylactic antibiotics and interferon-gamma. When infection is suspected, aggressive effort to obtain culture material is required. Treatment of infections involves prolonged use of systemic antibiotics, surgical debridement when feasible, and, in severe infections, use of granulocyte transfusions. Mouse knockout models of CGD have been created in which to examine aspects of pathophysiology and therapy. Gene therapy and bone marrow transplantation trials in CGD patients are ongoing and show great promise.

Eosinophil-specific regulation of gp91(phox) gene expression by transcription factors GATA-1 and GATA-2

The glycoprotein gp91(phox) is an essential component of the phagocyte NADPH oxidase and is expressed in eosinophils, neutrophils, monocytes, and B-lymphocytes. We previously suggested an eosinophil-specific mechanism of gp91(phox) gene expression. To elucidate the mechanism, we performed functional assays on deletion mutants of the gp91(phox) promoter in various types of gp91(phox)-expressing cells. A 10-base pair (bp) region from bp -105 to -96 of the promoter activated transcription of the gene in eosinophilic cells, but not in neutrophilic, monocytic, or B-lymphocytic cells. A 2-bp mutation introduced into the GATA site spanning bp -101 to -96 (-98GATA site) of the fragment abolished its activity. Gel shift assays using a GATA competitor and specific antibodies demonstrated that both GATA-1 and GATA-2 specifically bound to the -98GATA site with similar affinities. Individual transfection of GATA-1 and GATA-2 into Jurkat cells, which have neither endogenous GATA-1 nor GATA-2, activated the -105/+12 construct in a -98GATA site-dependent manner. Combined transfection of GATA-1 and GATA-2 activated the promoter less than transfection of GATA-1 alone. These results suggest that GATA-1 is an activator and that GATA-2 is a relative competitive inhibitor of GATA-1 in the expression of the gp91(phox) gene in human eosinophils.