Th2-driven Airway Inflammation Research Articles

Macrophage inflammatory and regenerative response periodicity is programmed by cell cycle and chromatin state

Cell cycle (CC) facilitates cell division via robust, cyclical gene expression. Protective immunity requires the expansion of pathogen-responsive cell types, but whether CC confers unique gene expression programs that direct the subsequent immunological response remains unclear. Here, we demonstrate that single macrophages (MFs) adopt different plasticity states in CC, which leads to heterogeneous cytokine-induced polarization, priming, and repolarization programs. Specifically, MF plasticity to interferon gamma (IFNG) is substantially reduced during S-G2/M, whereas interleukin 4 (IL-4) induces S-G2/M-biased gene expression, mediated by CC-biased enhancers. Additionally, IL-4 polarization shifts the CC-phase distribution of MFs toward the G2/M phase, providing a subpopulation-specific mechanism for IL-4-induced, dampened IFNG responsiveness. Finally, we demonstrate CC-dependent MF responses in murine and human disease settings invivo, including Th2-driven airway inflammation and pulmonary fibrosis, where MFs express an S-G2/M-biased tissue remodeling gene program. Therefore, MF inflammatory and regenerative responses are gated by CC in a cyclical, phase-dependent manner.

Respiratory health among office workers in Malaysia and endotoxin and (1,3)-β-glucan in office dust.

OBJECTIVE: To examine the associations between endotoxin and (1,3)-β-glucan concentrations in office dust and respiratory symptoms and airway inflammation among 695 office workers in Malaysia.METHODS: Health data were collected using a questionnaire, sensitisation testing and measurement of fractional exhaled nitric oxide (FeNO). Indoor temperature, relative air humidity (RH) and carbon dioxide (CO₂) were measured in the offices and settled dust was vacuumed and analysed for endotoxin and (1,3)-β-glucan concentrations. Associations were analysed by two level multiple logistic regression.RESULTS: Overall, 9.6% of the workers had doctor-diagnosed asthma, 15.5% had wheeze, 18.4% had daytime attacks of breathlessness and 25.8% had elevated FeNO (≥25 ppb). The median levels in office dust were 11.3 EU/mg endotoxin and 62.9 ng/g (1,3)-β-glucan. After adjusting for personal and home environment factors, endotoxin concentration in dust was associated with wheeze (P = 0.02) and rhinoconjunctivitis (P = 0.007). The amount of surface dust (P = 0.04) and (1,3)-β-glucan concentration dust (P = 0.03) were associated with elevated FeNO.CONCLUSION: Endotoxin in office dust could be a risk factor for wheeze and rhinoconjunctivitis among office workers in mechanically ventilated offices in a tropical country. The amount of dust and (1,3)-β-glucan (a marker of indoor mould exposure) were associated with Th2 driven airway inflammation.

Retnla overexpression attenuates allergic inflammation of the airway.

Resistin-like molecule alpha (Retnla), also known as ‘Found in inflammatory zone 1’, is a secreted protein that has been found in bronchoalveolar lavage (BAL) fluid of ovalbumin (OVA)-induced asthmatic mice and plays a role as a regulator of T helper (Th)2-driven inflammation. However, the role of Retnla in the progress of Th2-driven airway inflammation is not yet clear. To better understand the function of Retnla in Th2-driven airway inflammation, we generated Retnla-overexpressing (Retnla-Tg) mice. Retnla-Tg mice showed increased expression of Retnla protein in BAL fluid and airway epithelial cells. Retnla overexpression itself did not induce any alteration in lung histology or lung function compared to non-Tg controls. However, OVA-sensitized/challenged Retnla-Tg mice had decreased numbers of cells in BAL and inflammatory cells accumulating in the lung. They also showed a reduction in mucus production in the airway epithelium, concomitant with a decreased Muc5ac level. These results were accompanied by reduced levels of Th2 cytokines, including interleukin (IL)-4, IL-5, and IL-13, with no effect on levels of OVA-specific immunoglobulin isotypes. Furthermore, phosphorylation of ERK was markedly reduced in the lungs of OVA-challenged Retnla-Tg mice. Taken together, these results indicates that Retnla protects against Th2-mediated inflammation in an experimental mouse model of asthma, suggesting that therapeutic approaches to enhance the production of Retnla or Retnla-like molecules could be valuable for preventing allergic lung inflammation.

Modulation of expression in BEAS-2B airway epithelial cells of α-l-fucosidase A1 and A2 by Th1 and Th2 cytokines, and overexpression of α-l-fucosidase 2

Chronic Th2-driven airway inflammation with excessive mucus production occurs in asthma. The regulation of FUCA1 and FUCA2 gene expression and enzyme activity in response to asthma-associated Th2 cytokines and, for contrast, Th1 cytokine IFN-γ, were investigated in a human airway cell line. BEAS-2B cells were supplemented with Th2-derived cytokines (IL-13, IL-4, IL-5) or/and IFN-γ. RNA and cell supernatants from stimulated and unstimulated cells were collected over a period of 3 h. Alpha-L-fucosidase A1 and A2 gene expression were assessed using real time RT-PCR, while enzymatic activities were measured using a fluorescent assay. To characterise α-L-fucosidase A2, CHO-K1 and BEAS-2B cell lines were transiently transfected, the FUCA2 gene was overexpressed, and the protein was immunoprecipitated. The transcription of FUCA1 was upregulated (p < 0.01) in response to IFN-γ, suggesting that FUCA1 transcription and fucosidase activity are regulated in a Th1-dependent manner. The gene expression was the highest for 30 min after IFN-γ stimulation (>twofold induction), whereas secreted enzyme activity in BEAS-2B cells was significantly increased 1 h after IFN-γ addition. IL-4, IL-5 and IL-13 had no effect on FUCA1 and FUCA2 expression and activity. The IFN-γ-induced increase in expression and activity was repressed by the presence of the Th2 cytokine IL-5. Enzymatically active α-L-fucosidase 2 was immunoprecipitated from BEAS-2B cells, with highest activity at pH 4.9. IL-13, IL-4 and IL-5 have no effect on the expression of FUCA1 and FUCA2, but its expression is upregulated by IFN-γ, a Th1 cytokine. Active α-L-fucosidase 2 was overexpressed in BEAS-2B cells.

Asthma phenotyping, therapy, and prevention: what can we learn from systems biology?

Asthma has a high prevalence worldwide, and contributes significantly to the socioeconomic burden. According to a classical paradigm, asthma symptoms are attributable to an allergic, Th2-driven airway inflammation that causes airway hyperresponsiveness and results in reversible airway obstruction. Diagnosis and therapy are based mainly on these pathophysiologic concepts. However, these have increasingly been challenged by findings of recent studies, and the frequently observed failure in controlling asthma symptoms. Important recent findings are the protective "farm effect" in children, the possible prenatal mechanisms of this protection, the recognition of many different asthma phenotypes in children and adults, and the partly disappointing clinical effects of new targeted therapeutic approaches. Systems biology approaches may lead to a more comprehensive view of asthma pathophysiology and a higher success rate of new therapies. Systems biology integrates clinical and experimental data by means of bioinformatics and mathematical modeling. In general, the "-omics" approach, and the "mathematical modeling" approach can be described. Recently, several consortia have been attempting to bring together clinical and molecular data from large asthma cohorts, using novel experimental setups, biostatistics, bioinformatics, and mathematical modeling. This "systems medicine" approach to asthma will help address the different asthma phenotypes with adequate therapy and possibly preventive strategies.

Altered expression of microRNA in the airway wall in chronic asthma: miR-126 as a potential therapeutic target

BackgroundThe role of microRNAs (miRNAs) in regulating gene expression is currently an area of intense interest. Relatively little is known, however, about the role of miRNAs in inflammatory and immunologically-driven disorders. In a mouse model, we have previously shown that miRNAs are potentially important therapeutic targets in allergic asthma, because inhibition of miR-126, one of a small subset of miRNAs upregulated in the airway wall, effectively suppressed Th2-driven airway inflammation and other features of asthma. In the present study, we extended investigation of the therapeutic potential of miRNA inhibition to our well-established model of chronic asthma.MethodsFemale BALB/c mice were systemically sensitised with ovalbumin (OVA) and chronically challenged with low mass concentrations of aerosolised OVA for up to 6 weeks. Airway tissue was obtained by blunt dissection and RNA was isolated for miRNA profiling. On the basis of the results obtained, animals were subsequently treated with either an antagomir to miR-126 (ant-miR-126) or a scrambled control antagomir once weekly during the 6 weeks of chronic challenge, and the effects on airway inflammation and remodelling were assessed using established morphometric techniques.ResultsCompared to naïve mice, there was selective upregulation of a modest number of miRNAs, notably miR-126, in the airway wall tissue of chronically challenged animals. The relative increase was maximal after 2 weeks of inhalational challenge and subsequently declined to baseline levels. Compared to treatment with the scrambled control, ant-miR-126 significantly reduced recruitment of intraepithelial eosinophils, but had no effect on the chronic inflammatory response, or on changes of airway remodelling.ConclusionsIn this model of chronic asthma, there was an initial increase in expression of a small number of miRNAs in the airway wall, notably miR-126. However, this later declined to baseline levels, suggesting that sustained changes in miRNA may not be essential for perpetuation of chronic asthma. Moreover, inhibition of miR-126 by administration of an antagomir suppressed eosinophil recruitment into the airways but had no effect on chronic inflammation in the airway wall, or on changes of remodelling, suggesting that multiple miRNAs are likely to regulate the development of these lesions.

Research Highlights

ImmunotherapyVol. 3, No. 1 News & ViewsResearch HighlightsAna Belén Blázquez, Cristobalina Mayorga, Natalia Blanca-López & Maria José Torres JaénAna Belén BlázquezResearch laboratory for Allergic Diseases, IMABIS Fundation, Carlos Haya Hospital, Malaga, SpainSearch for more papers by this author, Cristobalina MayorgaResearch laboratory for Allergic Diseases, IMABIS Fundation, Carlos Haya Hospital, Malaga, SpainSearch for more papers by this author, Natalia Blanca-LópezAllergy Service, Infanta Leonor Hospital, Madrid, SpainSearch for more papers by this author & Maria José Torres Jaén† Author for correspondenceAllergy Service, Pabellón 5 Sótano, Carlos Haya Hospital (Pabellon C), Plaza del Hospital Civil, 29009 Malaga, Spain Search for more papers by this authorEmail the corresponding author at mjtorresj@gmail.comPublished Online:21 Dec 2010https://doi.org/10.2217/imt.10.98AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInRedditEmail View articleAbstractEvaluation of: Allam JP, Würtzen PA, Reinartz M et al.: Phl p 5 resorption in human oral mucosa leads to dose-dependent and time-dependent allergen binding by oral mucosal Langerhans cells, attenuates their maturation, and enhances their migratory and TGF-β1 and IL-10-producing properties. J. Allergy Clin. Immunol. 126, 638–645 (2010).AbstractEvaluation of: Shirinbank S, Taher YA, Maazi H et al.: Suppression of Th2-driven airway inflammation by allergen immunotherapy is independent of B cell and Ig responses in mice. J. Immunol. 185(7), 3857–3865 (2010).AbstractEvaluation of: Blumchen K, Ulbricht H, Staden U et al.: Oral peanut immunotherapy in children with peanut anaphylaxis. J. Allergy Clin. Immunol. 126, 83–91 (2010).FiguresReferencesRelatedDetails Vol. 3, No. 1 Follow us on social media for the latest updates Metrics Downloaded 276 times History Published online 21 December 2010 Published in print January 2011 Information© Future Medicine LtdPDF download

Suppression of ovalbumin-induced Th2-driven airway inflammation by β-sitosterol in a guinea pig model of asthma

In the present study, the efficacy of β-sitosterol isolated from an n-butanol extract of the seeds of the plant Moringa oleifera (Moringaceae) was examined against ovalbumin-induced airway inflammation in guinea pigs. All animals (except group I) were sensitized subcutaneously and challenged with aerosolized 0.5% ovalbumin. The test drugs, β-sitosterol (2.5 mg/kg) or dexamethasone (2.5 mg/kg), were administered to the animals (p.o.) prior to challenge with ovalbumin. During the experimental period (on days 18, 21, 24 and 29), a bronchoconstriction test (0.25% acetylcholine for 30 s) was performed and lung function parameters (tidal volume and respiration rate) were measured for each animal. On day 30, blood and bronchoalveolar lavaged fluid were collected to assess cellular content, and serum was collected for cytokine assays. Lung tissue was utilized for a histamine assay and for histopathology. β-sitosterol significantly increased the tidal volume (V t) and decreased the respiration rate ( f) of sensitized and challenged guinea pigs to the level of non-sensitized control guinea pigs and lowered both the total and differential cell counts, particularly eosinophils and neutrophils, in blood and bronchoalveolar lavaged fluid. Furthermore, β-sitosterol treatment suppressed the increase in cytokine levels (TNFα, IL-4 and IL-5), with the exception of IL-6, in serum and in bronchoalveolar lavaged fluid detected in model control animals. Moreover, treatment with β-sitosterol protected against airway inflammation in lung tissue histopathology. β-sitosterol possesses anti-asthmatic actions that might be mediated by inhibiting the cellular responses and subsequent release/synthesis of Th2 cytokines. This compound may have therapeutic potential in allergic asthma.

Suppression of Th2-Driven Airway Inflammation by Allergen Immunotherapy Is Independent of B Cell and Ig Responses in Mice

Allergen-specific immunotherapy (IT) uniquely renders long-term relief from allergic symptoms and is associated with elevated serum levels of allergen-specific IgG and IgA. The allergen-specific IgG response induced by IT treatment was shown to be critical for suppression of the immediate phase of the allergic response in mice, and this suppression was partially dependent on signaling through FcγRIIB. To investigate the relevance of the allergen-specific IgG responses for suppression of the Th2-driven late-phase allergic response, we performed IT in a mouse model of allergic asthma in the absence of FcγRIIB or FcγRI/FcγRIII signaling. We found that suppression of Th2 cell activity, allergic inflammation, and allergen-specific IgE responses is independent of FcγRIIB and FcγRI/FcγRIII signaling. Moreover, we show that the IT-induced allergen-specific systemic IgG or IgA responses and B cell function are dispensable for suppression of the late-phase allergic response by IT treatment. Finally, we found that the secretory mucosal IgA response also is not required for suppression of the Th2-driven allergic inflammation by IT. These data are in contrast to the suppression of the immediate phase of the allergic response, which is critically dependent on the induced allergen-specific serum IgG response. Hence, IT-induced suppression of the immediate and late phases of the allergic response is governed by divergent and independent mechanisms. Our data show that the IT-induced suppression of the Th2 cell-dependent late-phase allergic response is independent of the allergen-specific IgG and IgA responses that are associated with IT treatment.

Polycomb Group Gene Product Ring1B Regulates Th2-Driven Airway Inflammation through the Inhibition of Bim-Mediated Apoptosis of Effector Th2 Cells in the Lung

Polycomb group (PcG) gene products regulate the maintenance of homeobox gene expression in Drosophila and vertebrates. In the immune system, PcG molecules control cell cycle progression of thymocytes, Th2 cell differentiation, and the generation of memory CD4 T cells. In this paper, we extended the study of PcG molecules to the regulation of in vivo Th2 responses, especially allergic airway inflammation, by using conditional Ring1B-deficient mice with a CD4 T cell-specific deletion of the Ring1B gene (Ring1B(-/-) mice). In Ring1B(-/-) mice, CD4 T cell development appeared to be normal, whereas the differentiation of Th2 cells but not Th1 cells was moderately impaired. In an Ag-induced Th2-driven allergic airway inflammation model, eosinophilic inflammation was attenuated in Ring1B(-/-) mice. Interestingly, Ring1B(-/-) effector Th2 cells were highly susceptible to apoptosis in comparison with wild-type effector Th2 cells in vivo and in vitro. The in vitro experiments revealed that the expression of Bim was increased at both the transcriptional and protein levels in Ring1B(-/-) effector Th2 cells, and the enhanced apoptosis in Ring1B(-/-) Th2 cells was rescued by the knockdown of Bim but not the other proapoptotic genes, such as Perp, Noxa, or Bax. The enhanced apoptosis detected in the transferred Ring1B(-/-) Th2 cells in the lung of the recipient mice was also rescued by knockdown of Bim. Therefore, these results indicate that Ring1B plays an important role in Th2-driven allergic airway inflammation through the control of Bim-dependent apoptosis of effector Th2 cells in vivo.

UV irradiation after immunization induces type 1 regulatory T cells that suppress Th2-type immune responses via secretion of IL-10

It is well documented that exposure to ultraviolet (UV) radiation in sunlight before immunization suppresses systemic as well as local immune responses. We have previously shown that administrating UV irradiation 7 days after immunization also suppresses Th1- and Th2-driven antibody (Ab) via generation of antigen (Ag)-specific CD4(+) regulatory T cells. In this study, we specifically show that IL-10, which is produced by CD4(+) regulatory T cells generated in mice that received UV irradiation after immunization, mediates the suppression of Ab responses by inhibiting Th cell activation. In addition, IL-10 produced upon Ag-specific activation by UV-induced regulatory T cells also mediates bystander suppression. Furthermore, because UV irradiation after immunization effectively dampens both Th1 and Th2 immune responses, we further demonstrated that mice receiving UV irradiation after allergen sensitization had reduced Th2-driven airway inflammation and airway hyperreactivity (AHR). These results suggest that UV irradiation in pre-sensitized individuals induces Ag-specific IL-10 producing regulatory T cells representing type 1 regulatory T cells that suppress Th2 immunity and may have therapeutic potential for asthmatic patients.

Differential Regulatory Function of Resting and Preactivated Allergen-Specific CD4+CD25+ Regulatory T Cells in Th2-Type Airway Inflammation

Although CD4(+)CD25(+) regulatory T (Treg) cells are known to suppress Th1 cell-mediated immune responses, their effect on Th2-type immune responses remains unclear. In this study we examined the role of Treg cells in Th2-type airway inflammation in mice. Depletion and reconstitution experiments demonstrated that the Treg cells of naive mice effectively suppressed the initiation and development of Th2-driven airway inflammation. Despite effective suppression of Th2-type airway inflammation in naive mice, adoptively transferred, allergen-specific Treg cells were unable to suppress airway inflammation in allergen-presensitized mice. Preactivated allergen-specific Treg cells, however, could suppress airway inflammation even in allergen-presensitized mice by accumulating in the lung, where they reduced the accumulation and proliferation of Th2 cells. Upon activation, allergen-specific Treg cells up-regulated CCR4, exhibited enhanced chemotactic responses to CCR4 ligands, and suppressed the proliferation of and cytokine production by polarized Th2 cells. Collectively, these results demonstrated that Treg cells are capable of suppressing Th2-driven airway inflammation even in allergen-presensitized mice in a manner dependent on their efficient migration into the inflammatory site and their regulation of Th2 cell activation and proliferation.

CD137-Mediated Immunotherapy for Allergic Asthma

Polte T, Foell J, Werner C, et al. J Clin Invest. 2006;116:1025–1036 PURPOSE OF THE STUDY. Allergen-specific CD4+ T-helper 2 (Th2) cells are thought to be at the center of asthma pathogenesis because of their ability to secrete cytokines such as interleukin 4 (IL-4), IL-5, and IL-13, which result in many of the features of allergic inflammation. CD4+ cells recognize the allergen-derived target presented with class II on antigen-presenting cells along with costimulatory signals. One recently described costimulatory molecule is CD137. Studies using murine disease models have shown that stimulation of CD137 on T cells can modulate the immune system in beneficial ways, such as promoting tumor regression and suppressing autoimmunity. The authors of this study investigated the effect of CD137 stimulation on a murine model of allergic asthma. METHODS. Allergic airway inflammation was induced in BALB/cByJ mice in the well-established manner involving systemic immunization to ovalbumin with alum followed by repeated aerosolized ovalbumin exposure. Control, nonspecific, antibody-treated mice were compared with mice treated with a single dose of agonistic anti-CD137 antibody given either before ovalbumin sensitization or after establishment of airway inflammation. Immunologic responses to ovalbumin were measured by ovalbumin-induced proliferation, in vitro cytokine production, and ovalbumin-specific immunoglobulin E and G1 titers. Changes in frequency of lymphocyte populations (CD4+, CD8+, CD19+, and CD4+CD25+) were measured by flow cytometry of total splenocytes. Adoptive transfer experiments were also conducted with CD4+ cells into severe combined immunodeficiency animals after control or anti-CD137 treatment. RESULTS. A single dose of anti-CD137 treatment was effective in prevention of ovalbumin-induced airway inflammation and in vitro recall responses to ovalbumin continued to show suppressed Th2 cytokine responses (IL-4, IL-5, IL-13) and elevated Th1 (interferon γ [IFN-γ]) even after chronic ovalbumin exposure. Anti-CD137 given as a single dose after establishment of airway inflammation induced significant reduction of inflammation, even when given at a time point associated with chronic inflammation (32 weeks). In vitro cytokine responses were modulated by anti-CD137 treatment, which resulted in lower levels of ovalbumin-induced Th2 cytokines and elevated levels of IFN-γ in both lung and spleen cells. Anti-CD137 treatment was also associated with an increase of CD8+ cells and a decrease of CD19+ cells. The anti-CD137 affect was not entirely accounted for by this increase in CD8+ or IFN-γ, because inhibition of either resulted in only a partial reversal of its effect. Consistent with this, adoptively transferred CD4+ cells from animals that had been treated with anti-CD137 induced lower levels of airway inflammation compared with control-treated CD4+ cells. CONCLUSIONS. CD137 is a potentially important target molecule for the modulation of Th2 inflammation. REVIEWER COMMENTS. Asthma morbidity continues to rise in the pediatric population. This was the first report of the potential importance of the CD137 costimulatory pathway in the pathogenesis of Th2-driven airway inflammation. CD137 activation has been shown to be associated with both promotion of Th1 and regulatory T-cell activity in various disease models, and clinical trials targeting this pathway are likely to come soon for tumor immunology. Much more study is required, but this may emerge as an important new target for suppressing allergic inflammation.

Tc2 cells respond to soluble antigen in the respiratory tract and induce lung eosinophilia and bronchial hyperresponsiveness.

The key role of T helper 2 (Th2) cells in asthma is well established. In contrast, the function of CD8+ T cells producing a distinct cytokine profile similar to Th2 cells is largely unknown. To analyze a potential role of CD8+ T cell subsets, allergen-specific, in vitro-differentiated T cytotoxic (Tc1 or Tc2) cells from T cell receptor transgenic OT-I mice were adoptively transferred into naive C57BL/6 mice. Subsequent allergen challenge of mice injected with Tc1 cells (producing IFN-gamma but no IL-4) resulted in a neutrophilic airway inflammation without induction of bronchial hyperresponsiveness (BHR). In contrast, the inflammatory response of recipients of adoptively transferred Tc2 cells (producing high levels of IL-4 but little IFN-gamma) was characterized by significantly increased numbers of eosinophils and induction of BHR to methacholine. The response of antigen-specific CD8+ T cells to soluble antigen was also observed in an in vitro system. A low concentration of antigen was shown to favor the generation of Tc2 cells, whereas high antigen load resulted in the differentiation of Tc1 cells. Thus, allergen-specific Tc2 cells respond to inhaled soluble antigen, produce an inflammatory response qualitatively similar to Th2 cells and therefore may exacerbate the Th2-driven airway inflammation in asthma.