Testosterone Decreases House Dust Mite-Induced Type 2 and IL-17A-Mediated Airway Inflammation.
ABSTRACT: As adults, women are twice as likely as men to have asthma; however, the mechanisms explaining this sexual dimorphism remain unclear. Increased type 2 cytokines and/or IL-17A, leading to increased airway eosinophils and neutrophils, respectively, are associated with asthma. Previous studies showed that testosterone, signaling through the androgen receptor (AR), decreased Th2-mediated allergic inflammation and type 2 innate immune responses during allergic inflammation. Therefore, we hypothesized that testosterone and AR signaling attenuate type 2 and IL-17A-mediated airway inflammation. To test our hypothesis, sham-operated and gonadectomized female and male mice were intranasally challenged with house dust mite (HDM) or vehicle (PBS) for 3 wk. Testosterone decreased and ovarian hormones increased HDM-induced eosinophilic and neutrophilic inflammation, IgE production, and airway hyperresponsiveness, as well as decreased the numbers of IL-13+ CD4 Th2 cells and IL-17A+ CD4 Th17 cells in the lung. Next, using wild-type male and female mice and ARtfm male mice that are unable to signal through the AR, we determined AR signaling intrinsically attenuated IL-17A+ Th17 cells but indirectly decreased IL-13+ CD4 Th2 cells in the lung by suppressing HDM-induced IL-4 production. In vitro Th2 and Th17 differentiation experiments showed AR signaling had no direct effect on Th2 cell differentiation but decreased IL-17A protein expression and IL-23R mRNA relative expression from Th17 cells. Combined, these findings show AR signaling attenuated type 2 and IL-17A inflammation through different mechanisms and provide a potential explanation for the increased prevalence of asthma in women compared with men.
Project description:DCs are necessary and sufficient for induction of allergic airway inflammation. CD11b+ DCs direct the underlying Th2 immunity, but debate surrounds the function of CD103+ DCs in lung immunity and asthma after an allergic challenge. We challenged Batf3-/- mice, which lacked lung CD103+ DCs, with the relevant allergen house dust mite (HDM) as a model to ascertain their role in asthma. We show that acute and chronic HDM exposure leads to defective Th1 immunity in Batf3-deficient mice. In addition, chronic HDM challenge in Batf3-/- mice results in increased Th2 and Th17 immune responses and exacerbated airway inflammation. Mechanistically, Batf3 absence does not affect induction of Treg or IL-10 production by lung CD4+ T cells following acute HDM challenge. Batf3-dependent CD103+ migratory DCs are the main source of IL-12p40 in the mediastinal lymph node DC compartment in the steady state. Moreover, CD103+ DCs selectively increase their IL-12p40 production upon HDM administration. In vivo IL-12 treatment reverts exacerbated allergic airway inflammation upon chronic HDM challenge in Batf3-/- mice, restraining Th2 and Th17 responses without triggering Th1 immunity. These results suggest a protective role for lung CD103+ DCs to HDM allergic airway inflammation through the production of IL-12.
Project description:Airway epithelial cells (AEC) are increasingly recognized as a major signalling centre in the pathogenesis of allergic asthma. A previous study demonstrated that epithelial growth factor receptor (EGFR) signalling in AEC regulated key features of allergic airway disease. However, it is unclear what mediators are regulated by EGFR signalling in AEC, although the production of the pro-inflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is EGFR dependent in keratinocytes.To determine whether EGFR signalling regulates GM-CSF production by human AEC downstream of the clinically relevant mediators house dust mite (HDM) and interleukin (IL)-17A and in a mouse model of established allergic asthma.EGFR inhibitors were used to determine whether EGFR signalling regulates GM-CSF production by cultured human AEC in response to HDM and IL-17A. The roles of EGFR ligands, p38 mitogen-activated protein kinase (MAPK) and tumour necrosis factor-alpha (TNF-?) converting enzyme (TACE) were also assessed. To determine whether EGFR regulates GM-CSF as well as key asthma characteristics in vivo, mice were chronically exposed to HDM to establish allergic airway disease and then treated with the EGFR inhibitor Erlotinib.EGFR inhibition reduced HDM and IL-17A induced GM-CSF production in a dose-dependent manner in cultured human AEC. GM-CSF production also required amphiregulin, p38 MAPK signalling and protease/TACE activity. In mice with established allergic airway disease, EGFR inhibition reduced levels of GM-CSF and TNF-?, as well as airway hyperreactivity, cellular inflammation, smooth muscle thickening and goblet cell metaplasia without changes in IgE and Th1, Th2 and Th17 cytokines.Results link HDM, IL-17A, amphiregulin, EGFR and GM-CSF in a mechanistic pathway in AEC and demonstrate that EGFR regulates GM-CSF production and the severity of established disease in a clinically relevant asthma model. These results identify the EGFR?GM-CSF axis as a target for therapeutic development.
Project description:Allergic asthma is one of most famous allergic diseases, which develops lung and airway inflammation. Recent studies have revealed the relationship between the pathology of allergic asthma and the increase of host-derived DNA in inflamed lung, but the role of the DNA-recognizing innate immune receptor for the inflammation is unknown well. Here we investigated the role of Toll-Like Receptor 9 in the pathogenesis of allergic asthma without synthesized CpG-ODNs. To examine that, we analyzed the pathology and immunology of house-dust-mite (HDM)-induced allergic asthma in Tlr9-/- mice and TLR9-inhibitory-antibody-treated mice. In Tlr9-/- mice, airway hyperresponsiveness (AHR) and the number of eosinophils decreased, and production of the Th2 cytokines IL-13, IL-5, and IL-4 was suppressed, compared with in wild-type mice. Interestingly, unlike Th2 cytokine production, IL-17A production was increased in Tlr9-/- mice. Furthermore, production of IL-2, which decreases IL-17A production, was reduced in Tlr9-/- mice. Blockade of TLR9 by treatment with TLR9-inhibitory-antibody, NaR9, effectively suppressed the development of allergic asthma pathology. IL-17A production in NaR9-treated mice was enhanced, which is comparable to Tlr9-/- mice. These results suggest that the TLR9-IL-2 axis plays an important role in Th2 inflammation by modulating IL-17A production in HDM-induced allergic asthma and that targeting of TLR9 might be a novel therapeutic method for allergic asthma.
Project description:Asthma is a heterogeneous disease with many different phenotypes. Moderate and severe asthma phenotypes have been associated with increased neutrophils and increased Th17 cytokines, IL-17A, IL-17F, and IL-22, in the bronchoalveolar lavage fluid of patients. Th17 cytokines recruit neutrophils to the airway by increasing secretion of epithelial-derived neutrophilic chemokines. In addition, Th17 cytokines also induce mucous cell metaplasia and have pleotropic effects on airway smooth muscle resulting in airway narrowing. The role of Th17 cytokines in regulating Th2 cytokine expression and allergic airway inflammation remains unclear with conflicting reports. However, the role of Th17 cells in asthma will be answered in ongoing clinical trials with therapeutics targeting IL-17A and IL-17 receptor signaling.
Project description:The Th17 cytokines interleukin-17A (IL-17A), IL-17F, and IL-22 are critical for the lung immune response to a variety of bacterial pathogens, including Klebsiella pneumoniae. Th2 cytokine expression in the airways is a characteristic feature of asthma and allergic airway inflammation. The Th2 cytokines IL-4 and IL-13 diminish ex vivo and in vivo IL-17A protein expression by Th17 cells. To determine the effect of IL-4 and IL-13 on IL-17-dependent lung immune responses to acute bacterial infection, we developed a combined model in which allergic airway inflammation and lung IL-4 and IL-13 expression were induced by ovalbumin sensitization and challenge prior to acute lung infection with K. pneumoniae. We hypothesized that preexisting allergic airway inflammation decreases lung IL-17A expression and airway neutrophil recruitment in response to acute K. pneumoniae infection and thereby increases the lung K. pneumoniae burden. As hypothesized, we found that allergic airway inflammation decreased the number of K. pneumoniae-induced airway neutrophils and lung IL-17A, IL-17F, and IL-22 expression. Despite the marked reduction in postinfection airway neutrophilia and lung expression of Th17 cytokines, allergic airway inflammation significantly decreased the lung K. pneumoniae burden and postinfection mortality. We showed that the decreased lung K. pneumoniae burden was independent of IL-4, IL-5, and IL-17A and partially dependent on IL-13 and STAT6. Additionally, we demonstrated that the decreased lung K. pneumoniae burden associated with allergic airway inflammation was both neutrophil and CCL8 dependent. These findings suggest a novel role for CCL8 in lung antibacterial immunity against K. pneumoniae and suggest new mechanisms of orchestrating lung antibacterial immunity.
Project description:BACKGROUND:Recent studies have demonstrated that Th2 responses have the ability to antagonize Th17 responses. In mouse models of allergic asthma, blockade of Th2-effector cytokines results in elaboration of Th17 responses and associated increases in pulmonary neutrophilia. While these can be controlled by simultaneous blockade of Th17-associated effector cytokines, clinical trials of anti-IL-17/IL-17RA blocking therapies have demonstrated increased of risk of bacterial and fungal infections. Identification of minimally effective doses of cytokine-blocking therapies with the goal of reducing the potential emergence of infection-related complications is a translationally relevant goal. OBJECTIVE:In the current report, we examine whether combined blockade of IL-13 and IL-17A, at individually sub-therapeutic levels, can limit the development of allergic asthma while sparing expression of IL-17A-associated anti-microbial effectors. METHODS:House dust mite was given intratracheally to A/J mice. Anti-IL-13 and anti-IL-17A antibodies were administered individually, or concomitantly at sub-therapeutic doses. Airway hyper-reactivity, lung inflammation, magnitude of Th2- and Th17-associated cytokine production and expression of IL-13- and IL-17A-induced genes in the lungs was assessed. RESULTS:Initial dosing studies identified sub-therapeutic levels of IL-13 and IL-17A blocking mAbs that have a limited effect on asthma parameters and do not impair responses to microbial products or infection. Subsequent studies demonstrated that combined sub-therapeutic dosing with IL-13 and IL-17A blocking mAbs resulted in significant improvement in airway hyperresponsiveness (AHR) and expression of IL-13-induced gene expression. Importantly, these doses neither exacerbated nor inhibited production of Th17-associated cytokines, or IL-17A-associated gene expression. CONCLUSION:This study suggests that combining blockade of individual Th2 and Th17 effector cytokines, even at individually sub-therapeutic levels, may be sufficient to limit disease development while preserving important anti-microbial pathways. Such a strategy may therefore have reduced potential for adverse events associated with blockade of these pathways.
Project description:Previous studies have shown that IL-22, one of the Th17 cell-related cytokines, plays multiple roles in regulating allergic airway inflammation caused by antigen-specific Th2 cells; however, the underlying mechanism remains unclear. Here, we show that allergic airway inflammation and Th2 and Th17 cytokine production upon intratracheal administration of house dust mite (HDM) extract, a representative allergen, were exacerbated in IL-22-deficient mice. We also found that IL-22 induces Reg3? production from lung epithelial cells through STAT3 activation and that neutralization of Reg3? significantly exacerbates HDM-induced eosinophilic airway inflammation and Th2 cytokine induction. Moreover, exostatin-like 3 (EXTL3), a functional Reg3? binding protein, is expressed in lung epithelial cells, and intratracheal administration of recombinant Reg3? suppresses HDM-induced thymic stromal lymphopoietin and IL-33 expression and accumulation of type 2 innate lymphoid cells in the lung. Collectively, these results suggest that IL-22 induces Reg3? production from lung epithelial cells and inhibits the development of HDM-induced allergic airway inflammation, possibly by inhibiting cytokine production from lung epithelial cells.
Project description:Asthma is a heterogeneous chronic airway inflammation in which Th2 and Th17 cells are key players in its pathogenesis. We have reported that RhoA of Rho GTPases orchestrated glycolysis for Th2 cell differentiation and allergic airway inflammation by the use of a conditional RhoA-deficient mouse line. However, the role of RhoA in Th17 cells remains to be elucidated. In this study, we investigated the effects of RhoA deficiency on Th17 cells in the context of ex vivo cell culture systems and an in vivo house dust mites (HDM)-induced allergic airway inflammation. We found that RhoA deficiency inhibited Th17 differentiation and effector cytokine secretion, which was associated with the downregulations of Stat3 and Ror?t, key Th17 transcription factors. Furthermore, loss of RhoA markedly suppressed Th17 and neutrophil-involved airway inflammation induced by HDM in mice. The infiltrating inflammatory cells in the lungs and bronchoalveolar lavage (BAL) fluids were dramatically reduced in conditional RhoA-deficient mice. Th17 as well as Th2 effector cytokines were suppressed in the airways at both protein and mRNA levels. Interestingly, Y16, a specific RhoA inhibitor, was able to recapitulate the most phenotypes of RhoA genetic deletion in Th17 differentiation and allergic airway inflammation. Our data demonstrate that RhoA is a key regulator of Th17 cell differentiation and function. RhoA might serve as a potential novel therapeutic target for asthma and other inflammatory disorders.
Project description:Chitin, which is a major component of house dust mites (HDM), fungi, crustaceans, etc., can activate immune cells, suggesting that it contributes to development of allergic disorders such as asthma. Although the pathophysiological sensitization route of asthmatic patients to allergens is considered via the respiratory tract, the roles of intranasally-administered chitin in development of asthma remain unclear. After ovalbumin (OVA) challenge, development of airway inflammation was profoundly exacerbated in mice sensitized with OVA in the presence of chitin. The exacerbation was dependent on IL-33, but not IL-25, thymic stromal lymphopoietin or IL-17A. Chitin enhanced IL-33-dependent IL-1? production by dendritic cells (DCs). Furthermore, chitin- and IL-33-stimulated DC-derived IL-1? promoted OVA-specific Th2 cell activation, resulting in aggravation of OVA-induced airway inflammation. These findings indicate the adjuvant activity of chitin via a new mechanism and provide important clues for development of therapeutics for allergic disorders caused by HDM, fungi and crustaceans.
Project description:TLRs are a family of receptors that mediate immune system pathogen recognition. In the respiratory system, TLR activation has both beneficial and deleterious effects in asthma. For example, clinical data indicate that TLR6 activation exerts protective effects in asthma. Here, we explored the mechanism or mechanisms through which TLR6 mediates this effect using mouse models of Aspergillus fumigatus-induced and house dust mite antigen-induced (HDM antigen-induced) chronic asthma. Tlr6-/- mice with fungal- or HDM antigen-induced asthma exhibited substantially increased airway hyperresponsiveness, inflammation, and remodeling compared with WT asthmatic groups. Surprisingly, whole-lung levels of IL-23 and IL-17 were markedly lower in Tlr6-/- versus WT asthmatic mice. Tlr6-/- DCs generated less IL-23 upon activation with lipopolysaccharide, zymosan, or curdlan. Impaired IL-23 generation in Tlr6-/- mice also corresponded with lower levels of expression of the pathogen-recognition receptor dectin-1 and expansion of Th17 cells both in vivo and in vitro. Exogenous IL-23 treatment of asthmatic Tlr6-/- mice restored IL-17A production and substantially reduced airway hyperresponsiveness, inflammation, and lung fungal burden compared with that in untreated asthmatic Tlr6-/- mice. Together, our data demonstrate that TLR6 activation is critical for IL-23 production and Th17 responses, which both regulate the allergic inflammatory response in chronic fungal-induced asthma. Thus, therapeutics targeting TLR6 activity might prove efficacious in the treatment of clinical asthma.