Cells In Allergic Asthma Research Articles

Causal links between immune cells and asthma: Insights from a Mendelian Randomization analysis

Objectives Recent studies suggest immunophenotypes may play a role in asthma, but their causal relationship has not been thoroughly examined. Methods We used single nucleotide polymorphism (SNP)-derived instrumental variables. Summary data from 731 immune cell profiles and asthma cases were analyzed from genome-wide association studies (GWAS) of European populations. Mendelian Randomization (MR) analyses included inverse variance weighted (IVW), weighted median, and MR–Egger methods. Pleiotropy was assessed using the MR-Egger intercept and MR pleiotropy residual sum and outlier (MR-PRESSO) tests. Reverse MR analysis explored bidirectional causation between asthma and immunophenotypes. All statistical analyses were conducted using R software. Results MR analysis identified 108 immune signatures potentially contributing to asthma. Two immunophenotypes were significantly associated with asthma risk: CD4+ secreting Treg cells in allergic asthma (ORIVW = 1.078; 95% CI: 1.036–1.122; PIVW = 0.0002) and IgD + CD38− %lymphocyte cells in non-allergic asthma (ORIVW = 1.123; 95% CI: 1.057–1.194; PIVW = 0.0002). Conclusions This study highlights the causal associations between specific immunophenotypes and asthma risk, providing new insights into asthma pathogenesis.

Natural killer T cells in allergic asthma: implications for the development of novel immunotherapeutical strategies.

Allergic asthma has emerged as a prevalent allergic disease worldwide, affecting most prominently both young individuals and lower-income populations in developing and developed countries. To devise effective and curative immunotherapy, it is crucial to comprehend the intricate nature of this condition, characterized by an immune response imbalance that favors a proinflammatory profile orchestrated by diverse subsets of immune cells. Although the involvement of Natural Killer T (NKT) cells in asthma pathology is frequently implied, their specific contributions to disease onset and progression remain incompletely understood. Given their remarkable ability to modulate the immune response through the rapid secretion of various cytokines, NKT cells represent a promising target for the development of effective immunotherapy against allergic asthma. This review provides a comprehensive summary of the current understanding of NKT cells in the context of allergic asthma, along with novel therapeutic approaches that leverage the functional response of these cells.

Survey of immunopharmacological effects of botulinum toxin in cell signaling of bronchial smooth muscle cells in allergic asthma.

Asthma is a lung disease that has influenced more than 350 million people worldwide. Airway smooth muscle (ASM) spasm leads to airway hyperresponsiveness (AHR) and bronchial obstruction, which are clinical manifestations of an asthma attack. Botulinum toxin (BTX) is a bacteria toxin that acts as muscle relaxant and may have therapeutic effects on AHR and asthma. In this study, the effect of BTX on AHR and related gene expressions was evaluated. An asthma mice model was developed which was treated with BTX in two ways: intranasally (IN) and via nebulization (N) (0.01, 0.1, and 1 U/mL and 10 U/mL, respectively) on days 25, 27 and 29. AHR was evaluated on days 24, 26, 28, and 30, and gene expressions were evaluated for TrkA, TrkB, M1-M5, α7nAChR, TNF-α, and extracellular signal-regulated kinase 2 (ERK2) proteins. For histopathology of the lungs, perivascular and peribronchial inflammation, production of mucus, and goblet cell hyperplasia were studied. On day 24, treatment with BTX (for all doses) had no significant effect on AHR, but on days 26 and 28, AHR was decreased and this continued up to day 30 for all treated groups. Treatment with BTX had no significant effect on the gene expressions of TrkA, TrkB, M1-M5, α7nAChR, TNF-α, and ERK2 proteins, perivascular inflammation, peribronchial inflammation, hyperplasia of the goblet cell and production of mucus. Besides, mice administered with 10 mg/mL BTX perished. The BTX therapy controlled asthma attacks by decreasing AHR and relaxation of ASMs. However, BTX had no significant effect on airway inflammation and production of mucus. While using BTX, it is necessary to prescribe safe doses in order to prevent adverse reactions.

The effect of vitamin D on GATA3 gene expression in peripheral blood mononuclear cells in allergic asthma.

Asthma is becoming a major health problem in many countries. Immune responses in allergic asthma, as the most prevalent asthmatic phenotype, are mediated mostly by a subtype of T lymphocytes referred to as the effector lineage of Type 2 Th cells (Th2). The development of Th2 cells is mainly governed by a zinc finger transcription factor, i.e., GATA-binding protein 3 (GATA3). Allergic asthma is a complex disease, and vitamin D deficiency has been named as a non-genetic risk factor for its development. Vitamin D, a steroid hormone belonging to the family of nuclear receptors, has shown significant immunosuppressive effects in previous studies. In this study, given its immunomodulatory properties, we aimed to investigate the effects of different concentrations of vitamin D on GATA3 gene expression in peripheral blood mononuclear cells (PBMCs), including Th2 cells, and compare GATA3 expression levels between PBMCs taken from allergic asthmatic patients and healthy controls. The total sample size was 40 and the quantitative real-time PCR (qPCR) procedure was applied to assess the mRNA expression levels of GATA3 in different groups. Collectively, our results demonstrated that the expression of GATA3 in PBMCs taken from patients with allergic asthma is lower than in that from healthy controls. In addition, in the control group, cells co-cultured with vitamin D had a significantly increased GATA3 expression. However, in the patient group, such an increase was only observed in cells treated with 10⁻⁷M-vitamin D. By contrast, incubation with vitamin D at the concentration of 10-6 M slightly decreased the expression of GATA3 among patients. In summary, it is likely that vitamin D should regulate GATA3 gene expression in the PBMCs in a dose-dependent manner. The impacts of this steroid hormone can also differ between the status of health and allergic asthma in either extent or direction.

Androgen receptor suppresses inflammatory response of airway epithelial cells in allergic asthma through MAPK1 and MAPK14.

Dysfunction of airway epithelial cells in patients with asthma is closely with the occurrence and development of allergic asthma. Finding the differences of airway epithelium between asthmatic patients and normal patients is helpful to find out new treatment strategies. First, three original microarray datasets (GSE89809, GSE41861, GSE104468) from the Gene Expression Omnibus (GEO) dataset were used to assess differentially expressed genes in the epithelial tissues between patients with allergic asthma and healthy controls. Then, 10ng/mL TGF-β1 treated BEAS-2B cells and rats with ovalbumin induced allergic asthma were performed to confirm our assumption from the gene expression analysis with microarrays. Top ten hub significant difference genes were obtained by Cytohubba plug-in from GSE41861, and found that androgen receptor (AR) was closely associated with the mitogen-activated protein kinase (MAPK) pathway, especially MAPK1 and MAPK14. After treated with the TGF-β1 treated BEAS-2B cells and rats with allergic asthma, we found that 5α-dihydrotestosterone (5α-DHT), AR agonist, significantly decreased the Th2 inflammation (IL-25 and IL-33), MAPK1 and MAPK14 proteins expression in vitro and in vivo. The roles of 5α-DHT were similar with the results of chicanine (a p38 MAPK and ERK1/2 inhibitor), but the roles of 5α-DHT were masked by the C16-PAF (a MAPK and MEK/ERK activator) treatment. Androgen receptor limits the secretion of Th2 inflammatory factors by downregulating MAPK1 and MAPK14 in the TGF-β1 treated BEAS-2B cells and rats with ovalbumin induced allergic asthma, which plays a critical role for the therapeutics of patients with asthma.

Irg1/itaconate metabolic pathway is a crucial determinant of dendritic cells immune-priming function and contributes to resolute allergen-induced airway inflammation

Itaconate is produced from the mitochondrial TCA cycle enzyme aconitase decarboxylase (encoded by immune responsive gene1; Irg1) that exerts immunomodulatory function in myeloid cells. However, the role of the Irg1/itaconate pathway in dendritic cells (DC)-mediated airway inflammation and adaptive immunity to inhaled allergens, which are the primary antigen-presenting cells in allergic asthma, remains largely unknown. House dust mite (HDM)-challenged Irg1−/− mice displayed increases in eosinophilic airway inflammation, mucous cell metaplasia, and Th2 cytokine production with a mechanism involving impaired mite antigen presentations by DC. Adoptive transfer of HDM-pulsed DC from Irg1-deficient mice into naïve WT mice induced a similar phenotype of elevated type 2 airway inflammation and allergic sensitization. Untargeted metabolite analysis of HDM-pulsed DC revealed itaconate as one of the most abundant polar metabolites that potentially suppress mitochondrial oxidative damage. Furthermore, the immunomodulatory effect of itaconate was translated in vivo, where intranasal administration of 4-octyl itaconate 4-OI following antigen priming attenuated the manifestations of HDM-induced airway disease and Th2 immune response. Taken together, these data demonstrated for the first time a direct regulatory role of the Irg1/itaconate pathway in DC for the development of type 2 airway inflammation and suggest a possible therapeutic target in modulating allergic asthma.

Regulatory and IgE+ B Cells in Allergic Asthma.

Allergic asthma is triggered by inhalation of environmental allergens resulting in bronchial constriction and inflammation, which leads to clinical symptoms such as wheezing, coughing, and difficulty breathing. Asthmatic airway inflammation is initiated by inflammatory mediators released by granulocytic cells. However, the immunoglobulin E (IgE) antibody is necessary for the initiation of the allergic cascade, and IgE is produced and released exclusively by memory B cells and plasma cells. Acute allergen exposure has also been shown to increase IgE levels in the airways of patients diagnosed with allergic asthma; however, more studies are needed to understand local airway inflammation. Additionally, regulatory B cells (Bregs) have been shown to modulate IgE-mediated inflammatory processes in allergic asthma pathogenesis, particularly in mouse models of allergic airway disease. However, the levels and function of these IgE+ B cells and Bregs remain to be elucidated in human models of asthma. The overall objective for this chapter is to provide detailed methodological, and insightful technological advances to study the biology of B cells in allergic asthma pathogenesis. Specifically, we will describe how to investigate the frequency and function of IgE+ B cells and Bregs in allergic asthma, and the kinetics of these cells after allergen exposure in a human asthma model.

Specific Ag-guiding nano-vaccines attenuate neutrophil-dominant allergic asthma

Polymorphonuclear neutrophils (PMN) are one fraction of the major inflammatory cells in allergic asthma (asthma, in short); the role of PMN in the asthma pathogenesis is not fully understood yet. This study aims to investigate the effects of specific Ag-guiding exosomes on suppressing the neutrophil-dominant airway inflammation. In this study, BALB/c mice were immunized with ovalbumin plus complete Freund adjuvant to induce an asthma model featured with neutrophil-dominant lung inflammation. The Ag specific PMN (sPMN)-targeting exosomes (tExo), that were exosomes carrying a complex of specific Ag/anti-CD64 Ab and Fas ligand, were constructed to be used to alleviate neutrophilic asthma in mice. We found that sPMNs were the major cellular component in bronchoalveolar lavage fluid (BALF) in asthma mice, while less than 3% PMNs in naive control mice. The sPMNs expressed higher levels of CD64, which formed complexes with Ag-specific IgG (sIgG). The sIgG/CD64 complex-carrying PMNs could be activated upon exposing to specific Ags. Exposure to tExos induced Ag-specific PMNs apoptosis. Administration of tExos efficiently suppressed experimental asthma. We conclude that a fraction of sPMN was identified in the airway of asthma mice. The sPMNs could be activated upon exposure to specific Ags. tExos could induce sPMNs apoptosis, that show the translational potential in the treatment of asthma.

The mobilization effect of IL-25 on eosinophil progenitor cells in allergic asthma

Objective: Eosinophil progenitor cells (EoP) play a critical role in allergic airway inflammation in asthma. Previous studies have revealed that the expression of IL-25 receptor subunits (IL-17RA and IL-17RB) are increased on eosinophils (Eos) from allergic asthmatics upon allergen inhalation but few study has explored the role of IL-25 on EoP. Thus, in this research we examined the possible role of IL-25 on EoP in allergic asthmatics challenged by allergen, as well as in animal models where we verified the changes of newly produced Eos after IL-25 knockout. Methods: Asthmatics (n=14, during 2017-2018) who developed allergen-induced early and late responses were enrolled in this study. Blood was collected at pre-and 24 h post-challenge. Surface expression of IL-17RA and IL-17RB were evaluated by flow cytometry on EoP. In vitro migration assay was used to examine migrational responses of EoP and hematopoietic cells (HPC) from these subjects. In animal models, mice were grouped according to whether IL-25 was knock-out and whether mice were sensitized and challenged by ovalbumin (OVA) into asthmatic, control, knockout asthmatic and knockout control groups. Lung tissues, bronchoalveolar lavage flow (BALF) and bone marrow tissues of these mice were collected in order to evaluate airway inflammation and amount of newly produced (Brdu positive) and mature Eos. Results: EoP expressing IL-17RB were significantly increased after allergen inhalation in allergic asthmatics [(514±138) vs. (1146±450)/10(6) cells, pre-and post-challenge, F=6.819, P=0.022]. Pre-exposure to IL-25 primed the migrational responsiveness of EoP to stromal cell-derived factor (SDF)1α [(39.0±10.1)% vs. (73.0±7.9)%, control and IL-25 exposure groups respectively, P=0.021, 95% CI 5.19%~58.45%]. In OVA sensitized mice, knockout of IL-25 significantly reduced Eos and newly produced Eos percentage in the BALF [Eos, (7.8±2.0)% vs. (3.1±0.6)%, asthmatic and knockout asthmatic group respectively, P=0.002, 95% CI-7.57% to -1.98%; Brdu positive Eos, (50.0±7.6)% vs. (8.6±4.3)%, asthmatic and knockout asthmatic group respectively, P=0.011, 95% CI-72.41% to -10.27%], and newly produced Eos were also reduced in the bone marrow [(70.8±6.1)% vs. (1.3±1.3)%, asthmatic and knockout asthmatic group respectively, P=0.000, 95% CI -94.88% to -44.18%]. Conclusion: These results suggest an important role of IL-25 in allergen-induced EoP migration, local differentiation and eosinophilia in the airways.

Eosinophils count in peripheral circulation is associated with coronary artery disease

Background and aimsAllergic asthma can accelerate atherosclerosis, a disease in which plaque is deposited onto arterial walls and that may lead to coronary artery disease (CAD). Eosinophils are the most important effector cells in allergic asthma and are likely to become novel biomarkers for risk stratification of patients with CAD, but the relationship between eosinophil count and CAD remains unclear. We aimed to evaluate this relationship and the use of eosinophils in predicting CAD. MethodsA total of 5287 patients who underwent coronary angiography were recruited. Their biochemical parameters, including eosinophil count, were measured and their correlation with the severity of coronary artery stenosis, as quantified by the Gensini score system, was evaluated. ResultsThe percentages of eosinophils in leukocytes (PELs) were lower in CAD patients (p < 0.001), and had a significant negative correlation with Gensini scores (r = -0.112, p < 0.001). PELs were also significantly lower in acute myocardial infarction patients (p < 0.001). After adjusting for baseline differences, low PELs remained strongly associated with severe CAD and acute coronary arterial thrombotic event. Receiver-operating characteristic curve analysis showed that combining PELs with traditional risk factors in predictive models for CAD severity (z = 4.470, p < 0.001) or acute coronary arterial thrombotic event (z = 9.435, p < 0.001) improved the predictive capabilities of those models. ConclusionsPELs, at least in patients undergoing coronary angiography, may be strongly related to the subtype and severity of CAD and, therefore, eosinophil count may be an accurate and independent biomarker to predict CAD severity and acute coronary arterial thrombotic events.

The role of Th9 and other IL-9 producing cells in allergic asthma

The incidence of allergic asthma has been increasing year by year. It is estimated that there are more than 300 million illnesses. It is associated with increased IgE, mast cell activation, airway hyperreactivity, excessive mucus production, and airway remodeling. The traditional view is that allergic asthma is associated with allergic reactions involving T helper type 2 (Th2) cells. Recent studies have found that different subsets of CD4+ T cells (Th17, Th9) as well as innately immunized cells such as mast cells and innate lymphocyte type 2 (ILC2s) are able to produce cytokine IL-9, leading to asthma. Th9 cells develop from nave T cells to IL-9 producing cells in the presence of IL-4 and TGF-β. IRF4, GATA3, a basic leucine zipper transcription factor, several transcription factors downstream of BATF and IL-4 such as signal transduction and STAT6-activated NFAT are activated. In addition, the transcription factor PU.1 downstream of TGF-β signaling appears to be also critical for the development of Th9 cells. IL-9 is a pleiotropic cytokine that affects the function of different target cells such as T cells, B cells, mast cells and airway epithelial cells by activating STAT1, STAT3 and STAT5. Due to its versatility, IL-9 has been shown to be involved in several diseases such as cancer, autoimmunity and other pathogenmediated immunomodulatory diseases. This article reviews the role of Th9 and IL-9producing cells in allergic asthma.

Regulatory T Cells in Allergic Asthma

T regulatory cells (Tregs) are a subset of T cell leukocytes that play a key role in modulating the immune system, maintaining tolerance to self-antigens and suppressing excessive immune responses that go on to harm the host.Much like T helper (Th) cells, Tregs belong to a broader class of CD4+ T cells that develop from pluripotent hematopoietic stems cells in the bone marrow and mature in the thymus.Within the context of allergic asthma, Tregs are central to the process of pulmonary regulation by continuously combatting both immunogenic and harmless antigens. By releasing cytokines such as IL-10 and TGF-ß, Tregs modulate the inflammatory Th2-type immune response which, when dysregulated can drive asthma development as well as the hallmark asthmatic signs- airway hyperresponsiveness,bronchoconstriction, and gland hyperplasia/hypersecretion. This review will explore the function of Tregs as well as their modulatory role within allergic asthma.

Expansion of a CD26low Effector TH Subset and Reduction in Circulating Levels of sCD26 in Stable Allergic Asthma in Adults.

The pathogenesis of asthma is dependent on the balance between regulatory and effector T cells, which display differential expression of CD25 and CD26. Therefore, alteration of circulating levels of sCD25 and sCD26 during allergic asthma could be conditioned by changes in leukocyte phenotype. Objectives: To analyze expression of CD25 and CD26 on T lymphocytes and their soluble derivatives (sCD25, sCD26) during stable phases of moderate-severe allergic asthma. Cross-sectional study with 2 adult cohorts of allergic asthmatics. Clinical, anthropometric, pulmonary, hematological, and biochemical parameters were measured. Phenotyping was performed with flow cytometry in both circulating and cultured leukocytes. Dipeptidyl peptidase 4 (DPP4) activity was assayed in culture supernatants. In vitro studies revealed upregulation of CD26 on human T lymphocytes upon activation, especially under TH17-favoring conditions, and a correlation with soluble DPP4 activity (rs=0.641; P<.001). CD26 expression on lymphocytes was higher in asthmatics, while serum sCD26 was lower in women and patients. The latter finding could be associated with an expanded CD25low/CD26low/CD127low subset of effector CD4+ T cells in allergic asthma, with no changes in Treg percentages. However, women showed an increased Teff/Treg ratio, which could explain their greater susceptibility to asthma. Allergic asthma causes an increment in CD25lowCD26low helper T cells detected in stable stages. These changes are mirrored in serum and should be considered in the light of the downmodulating role of CD26 in major chemokines related to the pathogenesis of asthma such as CCL11 (eotaxin), CCL5 (RANTES), and CXCL12a (SDF-1α).

Fibrinogen cleavage products and Toll-like receptor 4 promote the generation of programmed cell death 1 ligand 2–positive dendritic cells in allergic asthma

Inhaled protease allergens preferentially trigger TH2-mediated inflammation in allergic asthma. The role of dendritic cells (DCs) on induction of TH2 cell responses in allergic asthma has been well documented; however, the mechanism by which protease allergens induce TH2-favorable DCs in the airway remains unclear. We sought to determine a subset of DCs responsible for TH2 cell responses in allergic asthma and the mechanism by which protease allergens induce the DC subset in the airway. Mice were challenged intranasally with protease allergens or fibrinogen cleavage products (FCPs) to induce allergic airway inflammation. DCs isolated from mediastinal lymph nodes were analyzed for surface phenotype and T-cell stimulatory function. Anti-Thy1.2 and Mas-TRECK mice were used to deplete innate lymphoid cells and mast cells, respectively. Adoptive cell transfer, bone marrow DC culture, anti-IL-13, and Toll-like receptor (TLR) 4-deficient mice were used for further mechanistic studies. Protease allergens induced a remarkable accumulation of TH2-favorable programmed cell death 1 ligand 2 (PD-L2)+ DCs in mediastinal lymph nodes, which was significantly abolished in mice depleted of mast cells and, to a lesser extent, innate lymphoid cells. Mechanistically, FCPs generated by protease allergens triggered IL-13 production from wild-type mast cells but not from TLR4-deficient mast cells, which resulted in an increase in the number of PD-L2+ DCs. Intranasal administration of FCPs induced an increase in numbers of PD-L2+ DCs in the airway, which was significantly abolished in TLR4- and mast cell-deficient mice. Injection of IL-13 restored the PD-L2+ DC population in mice lacking mast cells. Our findings unveil the "protease-FCP-TLR4-mast cell-IL-13" axis as a molecular mechanism for generation of TH2-favorable PD-L2+ DCs in allergic asthma and suggest that targeting the PD-L2+ DC pathway might be effective in suppressing allergic T-cell responses in the airway.

Increased IL-4- and IL-17-producing CD8+ cells are related to decreased CD39+CD4+Foxp3+ cells in allergic asthma

ABSTRACTObjective: In allergic asthma, regulatory T cell (Treg) number and function are decreased. Antigen-primed CD8+ T cells play an indispensable role in the full development of airway inflammation and airway hyper-responsiveness (AHR) occurring in asthma. In this study, we investigated the relationship between subpopulations of CD8+ T cells and CD39+ Tregs. Methods: Female C57BL/6 mice were used to develop the model of allergic asthma. Experimental mice were immunized with ovalbumin (OVA) by intra-peritoneal (i.p) injection and then challenged with OVA by intra-tracheal administration. Control mice were immunized with vehicle by i.p injection and challenged with OVA. Airway inflammation was determined by histology and AHR was measured by an invasive method. Levels of interferon (IFN)-γ, IL-4, and IL-17 in bronchoalveolar lavage fluid (BALF) were determined by enzyme-linked immunosorbent assay. The frequencies of CD8+IFN-γ+ cells (Tc1), CD8+IL-4+ cells (Tc2), CD8+IL-17+cells (Tc17), and CD39+Tregs were measured by flow cytometry. The correlation between CD39+Tregs and Tc subsets was analyzed by Pearson’s test. Results: Experimental mice displayed phenotypes of allergic asthma, including inflammatory cell infiltration into the lungs, goblet cell hyperplasia, increased airway resistance, and increased IL-4 and IL-17 in BALF. Compared to control mice, experimental mice displayed lower CD39+Tregs and Tc1 but higher Tc2 and Tc17. There was a negative correlation between CD39+Tregs and Tc2 or Tc17. Conclusion: In allergic asthma, increased Tc2 and Tc17 are possibly related to insufficient CD39+Tregs.

Accumulation of pulmonary vacuolated eosinophils in experimental allergic asthma that synergize with dendritic cells to induce Th-17 cells

Abstract Eosinophils are considered a homogenous cell population, contributing to the allergic asthma phenotype by promoting mucus hypersecretion and airway hyperresponsiveness. Here, we identified a previously unrecognized vacuolated CD11cdim eosinophilic population (vEOS) which accmulates exclusively in the lung tissue and in mediastinal lymph nodes but not in the airways in a house dust mite-mediated allergic asthma model and an IL-33 mediated pulmonary inflammation. In addition to the vEOS, we found classical SiglecF+CD11c− eosinophils (EOS) in the airways and the lung. Both cell types shared typical structural features of eosinophils and expressed CCR3. In contrast to EOS, vEOS expressed higher levels of the CD11a, CD11b and CD18 integrins. Immunofluorescence microscopy revealed that vEOS were located exclusively near arteries and airways, where they were in close contact with T cells. Moreover, vEOS took up antigen and expressed costimulatory molecules more efficiently than EOS. Consequently, in co-culture experiments with OVA-TCR transgenic T cells, vEOS and dendritic cells (DCs) drove T cell proliferation. However, in the presence of vEOS, T cells divided more frequently than in co-culture with DCs. Further, T cell activation in response to co-culture with vEOS together with DCs markedly enhanced IL-17 but not IL-13 production. Collectively, our data demonstrate that vEOS are an important subset of eosinophils, which differ from EOS in their location and their ability to activate T cells. Further, they suggest that cross-talk between vEOS and DCs might be a crucial step for the induction of Th17 cells in allergic asthma. Thus, vEOS may serve as an important target for Th17-associated steroid-resistant asthma.

Th9 and other IL-9-producing cells in allergic asthma.

Allergic asthma is a worldwide increasing chronic disease of the airways which affects more than 300 million people. It is associated with increased IgE, mast cell activation, airway hyperresponsiveness (AHR), mucus overproduction and remodeling of the airways. Previously, this pathological trait has been associated with T helper type 2 (Th2) cells. Recently, different CD4+ T cell subsets (Th17, Th9) as well as cells of innate immunity, like mast cells and innate lymphoid cells type 2 (ILC2s), which are all capable of producing the rediscovered cytokine IL-9, are known to contribute to this disease. Regarding Th9 cells, it is known that naïve T cells develop into IL-9-producing cells in the presence of interleukin-4 (IL-4) and transforming growth factor beta (TGFβ). Downstream of IL-4, several transcription factors like signal transducer and activator of transcription 6 (STAT6), interferon regulatory factor 4 (IRF4), GATA binding protein 3 (GATA3), basic leucine zipper transcription factor, ATF-like (BATF) and nuclear factor of activated T cells (NFAT) are activated. Additionally, the transcription factor PU.1, which is downstream of TGFβ signaling, also seems to be crucial in the development of Th9 cells. IL-9 is a pleiotropic cytokine that influences various distinct functions of different target cells such as T cells, B cells, mast cells and airway epithelial cells by activating STAT1, STAT3 and STAT5. Because of its pleiotropic functions, IL-9 has been demonstrated to be involved in several diseases, such as cancer, autoimmunity and other pathogen-mediated immune-regulated diseases. In this review, we focus on the role of Th9 and IL-9-producing cells in allergic asthma.

Critical roles of adenosine A2A receptor in regulating the balance of Treg/Th17 cells in allergic asthma.

Deficiency of Treg cells and hyperactivity of Th17 cells together are involved in the immunological pathogenesis of asthma. The adenosine A2A receptor (A2AR) plays a critical role in the increased Foxp3 expression of Treg cells and the decreased Th17 generation. The study aimed to investigate A2AR expression in peripheral blood and its regulatory effect on balance of Treg/Th17 cells in asthma. Thirty-one patients with chronic persistent asthma were recruited and divided into 18 intermittent to mild asthma patients, 13 moderate to severe asthma patients. A2AR, Foxp3, and ROR-γt mRNA expression levels in peripheral blood mononuclear cells (PBMCs) were measured by quantitative polymerase chain reaction (qPCR). TGF-β, IL-17, and IgE in plasma were detected with enzyme-linked immunosorbent assay (ELISA). Forty-two BALB/c mice were randomly, equally assigned to control group, ovalbumin (OVA) group and OVA + CGS (CGS21680, A2AR agonist) group. The infiltration of lung inflammation cells were evaluated by HE, A2AR, Foxp3, and ROR-γt mRNA in lung tissues measured by qPCR, TGF-β, IL-17, and IgE in plasma measured with ELISA, and IL-17 and TGF-β protein in lung tissues analyzed with immunohistochemical. Our results showed that expression A2AR mRNA in PBMCs was associated with asthma severity. Foxp3 mRNA, TGF-β, and FEV1%pred positively correlated with A2AR mRNA in asthma. ROR-γt mRNA and IL-17 negatively correlated with A2AR mRNA in asthma. CGS could promote Foxp3 mRNA expression, TGF-β, and improve lung function while inhibit ROR-γt mRNA expression, IL-17, and the infiltration of lung inflammation cells. A2AR could regulate the balance of Treg/Th17 cells in asthma.

A potential immunopathogenic role for reduced IL-35 expression in allergic asthma

Objective: Allergic asthma is a chronic airway inflammation resulting from an imbalance of T helper (Th) cell responses to allergens. Interleukin (IL)-35 has been shown to have potent immunoregulatory properties. Whether IL-35 participates in the immunopathogenesis of allergic asthma patients is still unknown. Methods: CD4+ T cells and CD4+CD25− T cells were obtained from peripheral blood mononuclear cells (PBMCs) using magnetic separation. The concentration of IL-35 in plasma was measured by enzyme-linked immunosorbent assay (ELISA). The mRNA expression levels of the IL-35 subunits, EBI3 and IL-12p35, were detected by quantitative real-time PCR (qPCR). The proliferative responses of CFSE-labeled CD4+CD25− T cells in the presence or absence of rhIL-35 were evaluated by flow cytometry. Cytokine production of activated CD4+CD25− T cells was examined by flow cytometry and ELISA. Results: IL-35 protein and mRNA levels were decreased in allergic asthmatics. The frequencies of CD4+CD25+Foxp3+ Tregs and CD4+IL-12p35+ T cells in allergic asthma patients were lower than in healthy controls. Moreover, the addition of rhIL-35 suppressed CFSE+CD4+CD25− T cell proliferation in vitro in a dose-dependent manner, and the suppression induced by rhIL-35 was associated with decreases in IL-4 but not IFN-γ and IL-17 production of activated CD4+CD25− T cells. The increased level of Th1/Th2 was observed in allergic asthmatics in the presence of rhIL-35. Conclusions: Our data suggest that IL-35 can effectively suppress the proliferation and IL-4 production of activated CD4+CD25− T cells in allergic asthma, and that IL-35 may be a new immunotherapy for asthma patients.

Dendritic cells induce Th2-mediated airway inflammatory responses to house dust mite via DNA-dependent protein kinase

DNA-dependent protein kinase (DNA-PK) mediates double stranded DNA break repair, V(D)J recombination, and immunoglobulin class switch recombination, as well as innate immune and pro-inflammatory responses. However, there is limited information regarding the role of DNA-PK in adaptive immunity mediated by dendritic cells (DCs), which are the primary antigen-presenting cells in allergic asthma. Here we show that house dust mite induces DNA-PK phosphorylation, which is a marker of DNA-PK activation, in DCs via the generation of intracellular reactive oxygen species. We also demonstrate that pharmacological inhibition of DNA-PK, as well as the specific deletion of DNA-PK in DCs, attenuates the induction of allergic sensitization and Th2 immunity via a mechanism that involves the impaired presentation of mite antigens. Furthermore, pharmacological inhibition of DNA-PK following antigen priming similarly reduces the manifestations of mite-induced airway disease. Collectively, these findings suggest that DNA-PK may be a potential target for treatment of allergic asthma.