Regulation of GATA-3, c-maf and T-bet mRNA expression in bronchoalveolar lavage cells and bronchial biopsies after segmental allergen challenge

Regulation of Eosinophilia in Asthma-New Therapeutic Approaches for Asthma Treatment

Asthma is a complex and chronic inflammatory disease of the airways, characterized by variable and recurring symptoms, reversible airflow obstruction, bronchospasm, and airway eosinophilia. As the pathophysiology of asthma is becoming clearer, the identification of new valuable drug targets is emerging. IL-5 is one of these such targets because it is the major cytokine supporting eosinophilia and is responsible for terminal differentiation of human eosinophils, regulating eosinophil proliferation, differentiation, maturation, migration, and prevention of cellular apoptosis. Blockade of the IL-5 pathway has been shown to be efficacious for the treatment of eosinophilic asthma. However, several other inflammatory pathways have been shown to support eosinophilia, including IL-13, the alarmin cytokines TSLP and IL-33, and the IL-3/5/GM-CSF axis. These and other alternate pathways leading to airway eosinophilia will be described, and the efficacy of therapeutics that have been developed to block these pathways will be evaluated.

Clinical relevance of Aspergillus fumigatus sensitization in cystic fibrosis

RATIONALE

The clinical relevance of sensitization to Aspergillus (A) fumigatus in cystic fibrosis (CF) is unclear. Some researchers propose that specific A fumigatus IgE is an innocent bystander, whereas others describe it as the major cause of TH-2-driven asthma-like disease.

OBJECTIVES

Lung function parameters in mild CF patients may be different in patients with and without A fumigatus sensitization. We aimed to ascertain whether allergen exposure to A fumigatus by bronchial allergen provocation (BAP) induces TH-2 inflammation comparable to an asthma-like disease.

METHODS

A total of 35 patients, aged 14.8 ± 8.5 years, and 20 healthy controls were investigated prospectively. The patients were divided into two groups: group 1 (n = 18): specific (s)IgE negative, and group 2 (n = 17): sIgE positive (≥0.7 KU/L) for A fumigatus. Lung function, exhaled NO, and induced sputum were analysed. All sensitized patients with an FEV1 > 75% (n = 13) underwent BAP with A fumigatus, and cell counts, and the expression of IL-5, IL-13, INF-γ, and IL-8 as well as transcription factors T-bet, GATA-3, and FoxP3, were measured.

RESULTS

Lung function parameters decreased significantly compared to controls, but not within the CF patient group. After BAP, 8 of 13 patients (61%) had a significant asthmatic response and increased eNO 24 hours later. In addition, marked TH-2-mediated inflammation involving eosinophils, IL-5, IL-13, and FoxP3 became apparent in induced sputum cells.

CONCLUSION

Our study demonstrated the clinical relevance of A fumigatus for the majority of sensitized CF patients. A distinct IgE/TH-2-dominated inflammation was found in induced sputum after A fumigatus exposure.

A Probiotic Mixture Regulates T Cell Balance and Reduces Atopic Dermatitis Symptoms in Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disorder with a complex etiology involving the immune response. Recent studies have demonstrated the role of certain probiotics in the treatment and prevention of AD. However, the mechanism by which these probiotics regulate the immune system remains unclear. In this study, we examined the immunomodulatory capacity of Duolac ATP, a mixed formulation of probiotics, both in vitro and in vivo. Results showed that the expression of programmed death-ligand 1(PD-L1) was significantly upregulated on bone marrow-derived dendritic cells (BMDCs) treated with Duolac ATP. Furthermore, the anti-inflammatory cytokines IL-10 and TGF-beta were both upregulated when BMDCs were treated with Duolac ATP. The percentage of proliferated regulatory T cells (Tregs) was enhanced when CD4⁺ T cells were co-cultured with Duolac ATP-treated BMDCs on plates coated with anti-CD3/CD28 antibodies. Intriguingly, IL-10 secretion from CD4⁺ T cells was also observed. The AD symptoms, histologic scores, and serum IgE levels in AD mice were significantly decreased after oral treatment with Duolac ATP. Moreover, the Th1-mediated response in AD-induced mice treated with oral Duolac ATP showed upregulation of IL-2 and IFN-gamma as well as of downstream signaling molecules T-bet, STAT-1, and STAT-4. Conversely, Duolac ATP suppressed Th2 and Th17 responses in AD-like mice, as evidenced by the downregulation of GATA-3, C-maf, IL-4, IL-5, and IL-17. Additionally, Duolac ATP increased the number of Tregs found at Peyer’s patches (PP) in treated AD mice. These results suggest that Duolac ATP modulates DCs to initiate both Th1 and Treg responses in AD mice. Thus, Duolac ATP represents a potential preventative agent against AD and could serve as an effective immunomodulator in AD patients.

GATA-3-specific DNAzyme - A novel approach for stratified asthma therapy

It is now well established that type-2 immune mechanisms drive the inflammation in about 50% of asthma patients. The major cellular and molecular players regulating this important network have been identified. In terms of therapeutic intervention, cytokine and cytokine-receptor pathways have been given major attention, since these molecules are relatively easily accessible for a blockade through monoclonal antibodies, and a number of positive clinical results support this concept. However, targeting events controlling the type-2 immunity network upstream of selective cytokine pathways would be equally attractive. Type-2 immunity is regulated through a delicate interplay of several transcription factors (including GATA-3, STAT-6, NFAT, IRF4, c-maf), with GATA-3 as master regulator in this regard. Since transcription factors are intracellularly located they cannot be directly targeted by monoclonal antibodies. For intracellular targets, antisense technologies such as antisense DNA and siRNA have been shown to be a promising approach, and have recently made major advances toward clinical application. Here, we summarize the development of a GATA-3-specific DNAzyme-a molecule class that combines the superior specificity of antisense molecules with an inherent RNA-cleaving enzymatic activity-for the treatment of type-2-driven asthma from preclinical development toward a proof-of-concept clinical study.

Protective association of TIM1-1454G>a polymorphism with asthma in a North Indian population

PURPOSE

TIM1 is a key regulator of Th2-dominated immune responses, including allergy, asthma, autoimmunity, and response to the pathogens. They are mainly expressed by hepatocytes and lymphoid cells. Analysis of the sequence of TIM1 was found to have range of SNPs which increases the transcriptional activity of the TIM1 gene.

METHODS

A case-control study was conducted with a total of 964 subjects, including 483 healthy controls and 481 asthma patients in the present study. DNA samples were extracted from blood, and genotyping was done using polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

Statistical analysis revealed that both heterozygous (GA) as well as the mutant (AA) genotype of -1454G>A (rs41297579) polymorphism shows resistance toward asthma with OR = 0.74, 95 % CI (0.55-0.98), p = 0.029 and OR = 0.43, 95 % CI (0.28-0.65), p = 0.000, respectively. The mutant (A) allele was also found to be highly protective toward asthma with OR = 0.68, 95 % CI (0.56-0.82) p = 0.000. However, no statistical difference was found between the TIM1-416G>C (rs9313422) polymorphism and asthma patients (p > 0.05).

CONCLUSIONS

This is the first study conducted in India conferring -1454G>A polymorphism provides resistance toward asthma while lack of association was found between -416G>C polymorphism and asthma in the studied North Indian population.

Expression of CD39 mRNA is altered in the peripheral blood of patients with allergic asthma

The ectoenzyme CD39 hydrolyzes extracellular adenosine 5'-triphosphate (ATP), which possesses pro-inflammatory properties. However, the role of CD39 in allergic asthma has not been fully elucidated. A total of 18 patients with persistent asthma who were allergic to house dust mites and 19 healthy volunteers were enrolled in this study. The expression of CD39, GATA3, RAR-related orphan receptor γ (ROR-γt) and forkhead box P3 (FoxP3) mRNA in peripheral blood mononuclear cells (PBMCs) was determined by SYBR-Green I quantitative polymerase chain reaction (qPCR). The cytokines interleukin (IL)-4, IL-17A, transforming growth factor β (TGF-β) and DP.sIgE were detected by enzyme-linked immunosorbent assay. Our data demonstrated that the expression of CD39 mRNA in PBMCs from asthmatic patients was significantly lower compared to that in normal controls [(1.49±0.59)×10^-3 vs. (2.17±0.77)×10^-3, respectively; P<0.01]. CD39 mRNA was negatively correlated with serum IL-4, IL-17A and GATA3 expression (r=-0.468, P<0.05; r=-0.550, P<0.05; and r=-0.424, P<0.01, respectively) and positively correlated with FoxP3 and TGF-β expression (r=0.373, P<0.05; and r=0.425, P<0.05, respectively). There was no obvious correlation between CD39 and ROR-γt expression (r=-0.259, P=0.122). These data suggested that CD39 mRNA expression was downregulated in allergic asthma, which was positively correlated with serum IL-4, IL-17A and GATA3 expression and negatively correlated with serum TGF-β and FoxP3 expression, whereas there was no correlation with ROR-γt. Therefore, it was hypothesized that CD39 may participate in the occurrence and progression of allergic asthma.

Airway responses and inflammation in subjects with asthma after four days of repeated high-single-dose allergen challenge

BACKGROUND

Both standard and low-dose allergen provocations are an established tool in asthma research to improve our understanding of the pathophysiological mechanism of allergic asthma. However, clinical symptoms are less likely to be induced. Therefore, we designed a protocol for repetitive high-dose bronchial allergen challenges to generate clinical symptoms and airway inflammation.

METHODS

A total of 27 patients aged 18 to 40 years with positive skin-prick tests and mild asthma underwent repetitive high-dose allergen challenges with household dust mites for four consecutive days. Pulmonary function and exhaled NO were measured at every visit. Induced sputum was analysed before and after the allergen challenges for cell counts, ECP, IL-5, INF-γ, IL-8, and the transcription factor Foxp3.

RESULTS

We found a significant decrease in pulmonary function, an increased use of salbutamol and the development of a late asthmatic response and bronchial hyperresponsiveness, as well as a significant induction of eNO, eosinophils, and Th-2 cytokines. Repeated provocation was feasible in the majority of patients. Two subjects had severe adverse events requiring prednisolone to cope with nocturnal asthma symptoms.

CONCLUSIONS

Repeated high-dose bronchial allergen challenges resulted in severe asthma symptoms and marked Th-2-mediated allergic airway inflammation. The high-dose challenge model is suitable only in an attenuated form in diseased volunteers for proof-of-concept studies and in clinical settings to reduce the risk of severe asthma exacerbations.

TRIAL REGISTRATION

ClinicalTrials.govNCT00677209.

Highly interconnected genes in disease-specific networks are enriched for disease-associated polymorphisms

Background

Complex diseases are associated with altered interactions between thousands of genes. We developed a novel method to identify and prioritize disease genes, which was generally applicable to complex diseases.

Results

We identified modules of highly interconnected genes in disease-specific networks derived from integrating gene-expression and protein interaction data. We examined if those modules were enriched for disease-associated SNPs, and could be used to find novel genes for functional studies. First, we analyzed publicly available gene expression microarray and genome-wide association study (GWAS) data from 13, highly diverse, complex diseases. In each disease, highly interconnected genes formed modules, which were significantly enriched for genes harboring disease-associated SNPs. To test if such modules could be used to find novel genes for functional studies, we repeated the analyses using our own gene expression microarray and GWAS data from seasonal allergic rhinitis. We identified a novel gene, FGF2, whose relevance was supported by functional studies using combined small interfering RNA-mediated knock-down and gene expression microarrays. The modules in the 13 complex diseases analyzed here tended to overlap and were enriched for pathways related to oncological, metabolic and inflammatory diseases. This suggested that this union of the modules would be associated with a general increase in susceptibility for complex diseases. Indeed, we found that this union was enriched with GWAS genes for 145 other complex diseases.

Conclusions

Modules of highly interconnected complex disease genes were enriched for disease-associated SNPs, and could be used to find novel genes for functional studies.

New targets for drug development in asthma

Asthma is a chronic inflammatory disease that affects about 300 million people worldwide, a total that is expected to rise to about 400 million over the next 15-20 years. Most asthmatic individuals respond well to the currently available treatments of inhaled corticosteroids and beta-adrenergic agonists; however, 5-10% have severe disease that responds poorly. Improved knowledge of asthma mechanisms has led to the recognition of different asthma phenotypes that might reflect distinct types of inflammation, explaining the effectiveness of anti-leucotrienes and the anti-IgE monoclonal antibody omalizumab in some patients. However, more knowledge of the inflammatory mechanisms within the airways is required. Improvements in available therapies-such as the development of fast-onset, once-a-day combination drugs with better safety profiles-will occur. Other drugs, such as inhaled p38 MAPK inhibitors and anti-oxidants, that target specific pathways or mediators could prove useful as monotherapies, but could also, in combination with corticosteroids, reduce the corticosteroid insensitivity often seen in severe asthma. Biological agents directed against the interleukin-13 pathway and new immunoregulatory agents that modulate functions of T-regulatory and T-helper-17 cells are likely to be successful. Patient-specific treatments will depend on the development of discriminatory handprints of distinct asthma subtypes and are probably over the horizon. Although a cure is unlikely to be developed in the near future, a greater understanding of disease mechanisms could bring such a situation nearer to reality.

New drugs targeting Th2 lymphocytes in asthma

Asthma represents a profound worldwide public health problem. The most effective anti-asthmatic drugs currently available include inhaled beta2-agonists and glucocorticoids and control asthma in about 90-95% of patients. The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term therapy. Although glucocorticoids are highly effective in controlling the inflammatory process in asthma, they appear to have little effect on the lower airway remodelling processes that appear to play a role in the pathophysiology of asthma at currently prescribed doses. The development of novel drugs may allow resolution of these changes. In addition, severe glucocorticoid-dependent and resistant asthma presents a great clinical burden and reducing the side-effects of glucocorticoids using novel steroid-sparing agents is needed. Furthermore, the mechanisms involved in the persistence of inflammation are poorly understood and the reasons why some patients have severe life threatening asthma and others have very mild disease are still unknown. Drug development for asthma has been directed at improving currently available drugs and findings new compounds that usually target the Th2-driven airway inflammatory response. Considering the apparently central role of T lymphocytes in the pathogenesis of asthma, drugs targeting disease-inducing Th2 cells are promising therapeutic strategies. However, although animal models of asthma suggest that this is feasible, the translation of these types of studies for the treatment of human asthma remains poor due to the limitations of the models currently used. The myriad of new compounds that are in development directed to modulate Th2 cells recruitment and/or activation will clarify in the near future the relative importance of these cells and their mediators in the complex interactions with the other pro-inflammatory/anti-inflammatory cells and mediators responsible of the different asthmatic phenotypes. Some of these new Th2-oriented strategies may in the future not only control symptoms and modify the natural course of asthma, but also potentially prevent or cure the disease.

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.

Expression of T-cell immunoglobulin- and mucin-domain-containing molecule-1 (TIM-1) is increased in a mouse model of asthma and relationship to GATA-3

It has been suggested that T-cell immunoglobulin-and mucin-domain-containing molecule-1 (TIM-1) plays an important role in the development of allergic asthma, though its molecular mechanism remains unclear. Our aim was to examine the expression of TIM-1 and Th2-associated transcription factor GATA-3 in asthmatic mice, and to evaluate the correlation of TIM-1 and GATA-3 in the pathogenesis of allergic asthma. We examined TIM-1 expression in lung tissue and peripheral blood mononuclear cells (PBMCs) of asthmatic mice by real-time PCR and flow cytometry, respectively; we also investigated TIM-1 and GATA-3 expression in the spleen tissue of asthmatic mice by western blot. These results demonstrate that TIM-1 was significantly increased in pulmonary tissues and PBMCs in asthmatic mice after ovalbumin (OVA) challenge (P<0.05), and that the production of TIM-1 as well as GATA-3 was upregulated in the spleen of asthmatic mice. The production of TIM-1 correlated significantly with the production of GATA-3 in the spleen of asthmatic mice (r=0.753, P<0.05). The results of this study provide the first evidence that increased expression of TIM-1 in asthmatic mice is associated with the Th2-associated transcription factor GATA-3. The findings suggest a possible mechanism for how HAV infection and TIM-1 upregulation influence the development of allergic asthma.

Effects of pollen and nasal glucocorticoid on FOXP3+, GATA-3+ and T-bet+ cells in allergic rhinitis

BACKGROUND

T-regulatory cells (Treg) affect the balance of T(H)2 and T(H)1 cells. Treg, T(H)2 and T(H)1 cells are regulated by the FOXP3, GATA-3 and T-bet transcription factors respectively. Our aim was to determine the number of FOXP3(+), GATA-3(+) and T-bet(+) cells in nasal mucosa in symptom-free allergic rhinitis (AR) patients vs healthy controls, as well as the effects of natural pollen exposure and concomitant nasal glucocorticoid treatment on these cells.

METHODS

Nasal biopsies were taken from healthy controls and patients with grass-pollen AR preseason. The AR patients were randomized to receive treatment with either fluticasone propionate (FP) or a placebo, and additional biopsies were taken during the pollen season. FOXP3(+), GATA-3(+) and T-bet(+) cells in nasal mucosa were quantified by immunohistochemistry.

RESULTS

The number of FOXP3(+) and GATA-3(+) cells, but not T-bet(+) cells, was significantly higher in AR patients vs controls preseason. The number of FOXP3(+) cells remained unchanged in the former group after the pollen season but decreased significantly in the nasal mucosa as a result of FP treatment. The pollen season substantially increased the number of GATA-3(+) cells, which was inhibited by FP. The number of T-bet(+) cells was not affected by pollen or FP.

CONCLUSION

These data suggest that nasal glucocorticoids attenuate the allergic inflammation partly by reducing the number of T(H)2 cells, but not by means of local upregulation of Treg cells. The local relationship between T(H)1 and T(H)2 cells as well as between Treg and T(H)2 is maintained by nasal glucocorticoid treatment.

Inverse association between T-cell immunoglobulin and mucin domain-1 and T-bet in a mouse model of allergic rhinitis

BACKGROUND

It has been suggested that human hepatitis A virus cellular receptor, also known as T-cell immunoglobulin and mucin domain-1 (TIM-1), plays an important role in the development of allergic diseases on the basis of epidemiologic data, but the molecular mechanism has been unclear. In a murine model of ovalbumin (OVA)-sensitized allergic rhinitis (AR), we examined the expression of TIM-1 and its correlation with T helper1-associated transcription factor, T-bet, as a potential mediator of T-cell immunoglobulin expression.

METHODS

Mice were challenged intranasally with OVA to elicit AR. The expression of TIM-1 in nasal tissues was examined by real-time reverse-transcription polymerase chain reaction (RT-PCR), and the surface expression of TIM-1 in peripheral blood mononuclear cells was evaluated by means of flow cytometry. In addition, the expression of TIM-1 as well as T-bet in splenic lymphocytes was examined by Western blotting.

RESULTS

TIM-1 mRNA was increased significantly in nasal tissues (P < .05) as seen by real-time RT-PCR. Flow cytometry indicated a differential TIM-1 expression of 135.5 +/- 34.2 in the AR group versus 51.1 +/- 10.9 in the control group (P < .05). The mean values of normalized TIM-1 were 0.43 +/- 0.18 and 0.21 +/- 0.10 in AR and control groups, respectively, whereas the mean values of normalized T-bet were 0.22 +/- 0.13 and 0.67 +/- 0.17 in the AR and control groups, respectively. There was a significant difference in the production of TIM-1 as well as T-bet in AR mice versus control mice (P < .05). The increased production of TIM-1 correlated significantly with the decreased T-bet in spleen tissue of AR mice (r = -0.52, P < .05).

CONCLUSION

Our experimental model recapitulates an increase in lymphocyte TIM-1 expression seen in AR both locally and systemically. Our results also demonstrate an inverse relationship between lymphocyte TIM-1 and T-bet expression, suggesting a possible mechanism that TIM-1 influences the development of AR.

Investigating Gata3 as a positional candidate gene for allergic asthma in a murine model

Gata3 is a positional candidate gene for allergic asthma. We determined allergen-induced GATA-3 mRNA and protein expression in asthma susceptible and resistant mice and generated Gata3 sequence data. Our data indicate that the Gata3 gene in isolation is not a causative agent of asthma susceptibility in our model.

IL-12-induced T-bet expression and IFNgamma release in lymphocytes from asthmatics--role of MAPkinases ERK-1/-2, p38(MAPK) and effect of dexamethasone

The transcription factor T-box-expressed-in-T-cells (T-bet) is required for T(H)1 lymphocyte differentiation, regulates the IL-12-induced expression of the T(H)1-specific cytokine IFNgamma and may be dysregulated in asthmatics. The modulatory role of extracellular signal-regulated kinase (ERK)-1/-2, p38mitogen-activated protein kinase (MAPK) and dexamethasone on IL-12 induced T-bet and IFNgamma expression was assessed in peripheral blood lymphocytes of 10 atopic asthmatics and 10 nonatopic normals. IFNgamma production was dependent on phosphorylation of ERK-1/-2 and p38MAPK, as examined by PD098059, an inhibitor of the upstream activator of MAPKkinase (MKK-1), and SB203580, an inhibitor of p38MAPK. The inhibitory effect of PD098059 on IFNgamma release was decreased in asthmatic T-cells compared with normals. The IL-12-induced T-bet expression and the inhibitory effect of SB203580 were increased in asthmatic T-cells compared with normals. Dexamethasone blocked the IL-12-induced T-bet expression in asthmatic T-cells completely and decreased IL-12-induced IFNgamma release by approximately 50%, which occurred to the same extent in asthmatic and normal T-cells. In conclusion, (1) p38MAPK-pathway rather than ERK-pathway may play a more basic role in the regulation of the increased T-bet expression in asthma, and (2) ERK- and p38MAPK-activation modulate IFNgamma expression independently of T-bet and this regulatory role of ERK-1/-2 on IFNgamma release is impaired in asthma. The therapeutic benefit of dexamethasone on T-bet and IFNgamma production seems to be critical.