Intelectin contributes to allergen-induced IL-25, IL-33, and TSLP expression and type 2 response in asthma and atopic dermatitis.
ABSTRACT: The epithelial and epidermal innate cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) have pivotal roles in the initiation of allergic inflammation in asthma and atopic dermatitis (AD). However, the mechanism by which the expression of these innate cytokines is regulated remains unclear. Intelectin (ITLN) is expressed in airway epithelial cells and promotes allergic airway inflammation. We hypothesized that ITLN is required for allergen-induced IL-25, IL-33, and TSLP expression. In two asthma models, Itln knockdown reduced allergen-induced increases in Il-25, Il-33, and Tslp and development of type 2 response, eosinophilic inflammation, mucus overproduction, and airway hyperresponsiveness. Itln knockdown also inhibited house dust mite (HDM)-induced early upregulation of Il-25, Il-33, and Tslp in a model solely inducing airway sensitization. Using human airway epithelial cells, we demonstrated that HDM-induced increases in ITLN led to phosphorylation of epidermal growth factor receptor and extracellular-signal regulated kinase, which were required for induction of IL-25, IL-33, and TSLP expression. In two AD models, Itln knockdown suppressed expression of Il-33, Tslp, and Th2 cytokines and eosinophilic inflammation. In humans, ITLN1 expression was significantly increased in asthmatic airways and in lesional skin of AD. We conclude that ITLN contributes to allergen-induced Il-25, Il-33, and Tslp expression in asthma and AD.
Project description:Overexpression of the transforming growth factor ? family signalling molecule smad2 in the airway epithelium provokes enhanced allergen-induced airway remodelling in mice, concomitant with elevated levels of interleukin (IL)-25.We investigated whether IL-25 plays an active role in driving this airway remodelling.Anti-IL-25 antibody was given to mice exposed to either inhaled house dust mite (HDM) alone, or in conjunction with an adenoviral smad2 vector which promotes an enhanced remodelling phenotype.Blocking IL-25 in allergen-exposed mice resulted in a moderate reduction in pulmonary eosinophilia and levels of T helper type 2 associated cytokines, IL-5 and IL-13. In addition, IL-25 neutralisation abrogated peribronchial collagen deposition, airway smooth muscle hyperplasia and airway hyperreactivity in control mice exposed to HDM and smad2-overexpressing mice. IL-25 was shown to act directly on human fibroblasts to induce collagen secretion. Recruitment of endothelial progenitor cells to the lung and subsequent neovascularisation was also IL-25 dependent, demonstrating a direct role for IL-25 during angiogenesis in vivo. Moreover, the secretion of innate epithelial derived cytokines IL-33 and thymic stromal lymphopoietin (TSLP) was completely ablated.In addition to modulating acute inflammation, we now demonstrate a role for IL-25 in orchestrating airway remodelling. IL-25 also drives IL-33 and TSLP production in the lung. These data delineate a wider role for IL-25 in mediating structural changes to the lung following allergen exposure and implicate IL-25 as a novel therapeutic target for the treatment of airway remodelling in asthma.
Project description:Interleukin-33 (IL-33) activates group 2 innate lymphoid cells (ILC2), resulting in T-helper-2 inflammation in bronchial asthma. Airway epithelial cells were reported as sources of IL-33 during apoptosis and necrosis. However, IL-33 is known to be from sources other than airway epithelial cells such as leukocytes, and the mechanisms of IL-33 production and release are not fully understood. The aim of this study was to clarify the role of IL-33 production by monocytes in airway inflammation.BALB/c mice were sensitized and challenged with a house dust mite (HDM) preparation. Airway inflammation was assessed by quantifying inflammatory cells in bronchoalveolar lavage (BAL) fluid, and IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) levels in lung. Immunohistochemistry for IL-33 in lung sections was also performed. Ly6c, CD11b, and CD11c expression was examined by flow cytometry. Clodronate liposomes were used in the HDM-airway inflammation model to deplete circulating monocytes.The IL-33, but not IL-25 or TSLP, level in lung homogenates was markedly increased in HDM mice compared to control mice. IL-33-positive cells in the lungs were identified using immunohistochemistry and were increased in areas surrounding bronchi and vasculature. Furthermore, IL-33 levels were increased in mononuclear cells derived from lungs of HDM mice compared to controls. The expression of Ly6c in mononuclear cells was significantly higher in HDM mice than in controls. Treatment with clodronate liposomes led to inhibition of not only inflammatory cells in BAL fluid, airway hyper reactivity and Th2 cytokines in lung, but also IL-33 in lung.IL-33 from monocytes recruited to the lung may contribute to the pathogenesis of HDM-induced airway inflammation.
Project description:CD93 has been shown critical roles in inflammatory and immune diseases. However, in allergic asthma, the potential roles of soluble CD93 (sCD93) have not been well studied. We conducted house dust mite (HDM) stimulation with Der p 1 in BEAS-2B and U937 cells, followed by treatment with dexamethasone or small interfering RNA against CD93. A HDM-induced murine allergic asthma model was also established. We estimated the power of sCD93 to predict allergic asthma in a retrospective post-hoc analysis containing 96 human samples. HDM-stimulated BEAS-2B cells showed increased mRNA expression levels of IL-6, IL-8, IL-33, TSLP, and CD93. The CD93 level in culture supernatants steadily increased for 24?h after allergen stimulation, which was significantly suppressed by both dexamethasone and CD93 silencing. CD93 silencing increased IL-6 and TSLP, but not IL-33 levels in culture supernatants. HDM-induced asthma mice showed significant airway hyperresponsiveness and inflammation with Th2 cytokine activation, along with decreased CD93 expression in bronchial epithelial cells and lung homogenates but increased serum CD93 levels. The sCD93 level in asthma patients was significantly higher than that in healthy controls and could predict asthma diagnosis with moderate sensitivity (71.4%) and specificity (82.4%) (AUC?=?0.787, P?<?0.001). The level of sCD93 which has potential role to predict asthma significantly increased after HDM stimulation via IL-6 and TSLP in vitro and in vivo.
Project description:BACKGROUND:Environmental pollutants, which coexist with allergens, have been associated with the exacerbation of asthma. However, the underlying molecular mechanisms remain elusive. We sought to determine whether benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced asthma and its underlying mechanisms. METHODS:The effect of BaP was investigated in Der f 1-induced mouse model of asthma, including airway hyper-responsiveness, allergic inflammation, and epithelial-derived cytokines. The impact of BaP on Der f 1-induced airway epithelial cell oxidative stress (ROS) and cytokine release was further analyzed. The role of aryl hydrocarbon receptor (AhR) signaling in BaP-promoted Der f 1-induced ROS, cytokine production, and allergic inflammation was also investigated. RESULTS:Compared with Der f 1, BaP co-exposure with Der f 1 led to airway hyper-responsiveness and increased lung inflammation in mouse model of asthma. Increased expression of TSLP, IL-33, and IL-25 was also found in the airways of these mice. Moreover, BaP co-exposure with Der f 1 activated AhR signaling with increased expression of AhR and CYP1A1 and promoted airway epithelial ROS generation and TSLP and IL-33, but not IL-25, expression. Interestingly, AhR antagonist CH223191 or cells with AhR knockdown abrogated the increased expression of ROS, TSLP, and IL-33. Furthermore, ROS inhibitor N-acetyl-L-cysteine (NAC) also suppressed BaP co-exposure-induced expression of epithelial TSLP, IL-33, and IL-25. Finally, AhR antagonist CH223191 and NAC inhibited BaP co-exposure with Der f 1-induced lung inflammation. CONCLUSIONS:Our findings suggest that BaP facilitates Der f 1-induced epithelial cytokine release through the AhR-ROS axis.
Project description:BACKGROUND:IL-33 plays an important role in the development of experimental asthma. OBJECTIVE:We sought to study the role of the IL-33 receptor suppressor of tumorigenicity 2 (ST2) in the persistence of asthma in a mouse model. METHODS:We studied allergen-induced experimental asthma in ST2 knockout (KO) and wild-type control mice. We measured airway hyperresponsiveness by using flexiVent; inflammatory indices by using ELISA, histology, and real-time PCR; and type 2 innate lymphoid cells (ILC2s) in lung single-cell preparations by using flow cytometry. RESULTS:Airway hyperresponsiveness was increased in allergen-treated ST2 KO mice and comparable with that in allergen-treated wild-type control mice. Peribronchial and perivascular inflammation and mucus production were largely similar in both groups. Persistence of experimental asthma in ST2 KO mice was associated with an increase in levels of thymic stromal lymphopoietin (TSLP), IL-9, and IL-13, but not IL-5, in bronchoalveolar lavage fluid. Expectedly, ST2 deletion caused a reduction in IL-13+ CD4 T cells, forkhead box P3-positive regulatory T cells, and IL-5+ ILC2s. Unexpectedly, ST2 deletion led to an overall increase in innate lymphoid cells (CD45+lin-CD25+ cells) and IL-13+ ILC2s, emergence of a TSLP receptor-positive IL-9+ ILC2 population, and an increase in intraepithelial mast cell numbers in the lung. An anti-TSLP antibody abrogated airway hyperresponsiveness, inflammation, and mucus production in allergen-treated ST2 KO mice. It also caused a reduction in innate lymphoid cell, ILC2, and IL-9+ and IL-13+ ILC2 numbers in the lung. CONCLUSIONS:Genetic deletion of the IL-33 receptor paradoxically increases TSLP production, which stimulates the emergence of IL-9+ and IL-13+ ILC2s and mast cells and leads to development of chronic experimental asthma. An anti-TSLP antibody abrogates all pathologic features of asthma in this model.
Project description:Although atopic dermatitis (AD) is the initial step of the "atopic march", a progression from AD to asthma, the underlying mechanism remains unknown. Selective expression of IL-13 in the skin of mice caused an AD phenotype resembling human AD, and the disorder was associated with enhanced production of thymic stromal lymphopoietin (TSLP) in the AD skin with a systemic Th2 immunity. Here we show that IL-13 transgenic mice with AD had significantly enhanced lung inflammation, mucus hypersecretion, and airway hyperresponsiveness (AHR) when sensitized and challenged by allergen. In addition, the level of TSLP was significantly higher in acute AD than in chronic AD. Furthermore, elimination of TSLP signaling significantly diminished the allergic asthma responses, immune cell production of Th2 cytokines (IL-4, IL-13), and serum IgE. These studies indicate that IL-13 induces AD and atopic march via a TSLP dependent mechanism.
Project description:Allergic asthma is a chronic immune-inflammatory disease of the airways. Despite aeroallergen exposure being universal, allergic asthma affects only a fraction of individuals. This is likely related, at least in part, to the extent of allergen exposure. Regarding house dust mite (HDM), we previously identified the threshold required to elicit allergic responses in BALB/c mice. Here, we investigated the impact of an initial immune perturbation on the response to sub-threshold HDM exposure. We show that transient GM-CSF expression in the lung facilitated robust eosinophilic inflammation, long-lasting antigen-specific Th2 responses, mucus production and airway hyperresponsiveness. This was associated with increased IL-33 levels and activated CD11b(+) DCs expressing OX40L. GM-CSF-driven allergic responses were significantly blunted in IL-33-deficient mice. IL-33 was localized on alveolar type II cells and in vitro stimulation of human epithelial cells with GM-CSF enhanced intracellular IL-33 independently of IL-1?. Likewise, GM-CSF administration in vivo resulted in increased levels of IL-33 but not IL-1?. These findings suggest that exposures to environmental agents associated with GM-CSF production, including airway infections and pollutants, may decrease the threshold of allergen responsiveness and, hence, increase the susceptibility to develop allergic asthma through a GM-CSF/IL-33/OX40L pathway.
Project description:Viral-induced asthma exacerbations, which exhibit both Th1-type neutrophilia and Th2-type inflammation, associate with secretion of Interleukin (IL)-1?. IL-1? induces neutrophilic inflammation. It may also increase Th2-type cytokine expression. We hypothesised that IL-1? is causally involved in both Th1 and Th2 features of asthma exacerbations. This hypothesis is tested in our mouse model of viral stimulus-induced asthma exacerbation.Wild-type (WT) and IL-1? deficient (IL-1?-/-) mice received house dust mite (HDM) or saline intranasally during three weeks followed by intranasal dsRNA (PolyI:C molecule known for its rhinovirus infection mimic) for three consecutive days to provoke exacerbation. Bronchoalveolar lavage fluid was analysed for inflammatory cells and total protein. Lung tissues were stained for neutrophilic inflammation and IL-33. Tissue homogenates were analysed for mRNA expression of Muc5ac, CXCL1/KC, TNF-?, CCL5, IL-25, TSLP, IL-33, IL-1?, CCL11 and CCL2 using RT-qPCR.Expression of IL-1?, neutrophil chemoattractants, CXCL1 and CCL5, the Th2-upstream cytokine IL-33, and Muc5ac were induced at exacerbation in WT mice and were significantly inhibited in IL-1?-/- mice at exacerbation. Effects of HDM alone were not reduced in IL-1?-deficient mice.Without being involved in the baseline HDM-induced allergic asthma, IL-1? signalling was required to induce neutrophil chemotactic factors, IL-33, and Muc5ac expression at viral stimulus-induced exacerbation. We suggest that IL-1? has a role both in neutrophilic and Th2 inflammation at viral-induced asthma exacerbations.
Project description:Loss of airway epithelial integrity contributes significantly to asthma pathogenesis. Thymic stromal lymphopoietin (TSLP) may have dual immunoregulatory roles. In inflammatory disorders of the bowel, the long isoform of TSLP (lfTSLP) promotes inflammation while the short isoform (sfTSLP) inhibits inflammation. We hypothesize that lfTSLP contributes to house dust mite (HDM)-induced airway epithelial barrier dysfunction and that synthetic sfTSLP can prevent these effects. In vitro, airway epithelial barrier function was assessed by monitoring transepithelial electrical resistance, fluorescent-dextran permeability, and distribution of E-cadherin and ?-catenin. In vivo, BALB/c mice were exposed to HDM by nasal inhalation for 5 consecutive days per week to establish an asthma model. sfTSLP and 1?,25-Dihydroxyvitamin D3 (1,25D3) were administered 1?h before HDM exposure. After 8 weeks, animal lung function tests and pathological staining were performed to evaluate asthma progression. We found that HDM and lfTSLP impaired barrier function. Treatment with sfTSLP and 1,25D3 prevented HDM-induced airway epithelial barrier disruption. Moreover, sfTSLP and 1,25D3 treatment ameliorated HDM-induced asthma in mice. Our data emphasize the importance of the different expression patterns and biological properties of sfTSLP and lfTSLP. Moreover, our results indicate that sfTSLP and 1,25D3 may serve as novel therapeutic agents for individualized treatment of asthma.
Project description:Epithelial-mesenchymal transition (EMT) is essential in asthma airway remodeling. IL-33 from epithelial cells is involved in pulmonary fibrosis. CD146 has been extensively explored in cancer-associated EMT. Whether IL-33 regulates CD146 in the EMT process associated with asthma airway remodeling is still largely unknown. We hypothesized that EMT in airway remodeling was regulated by the IL-33/CD146 axis. House dust mite (HDM) extract increased the expression of IL-33 and CD146 in epithelial cells. Increased expression of CD146 in HDM-treated epithelial cells could be blocked with an ST2-neutralizing antibody. Moreover, HDM-induced EMT was dependent on the CD146 and TGF-?/SMAD-3 signaling pathways. IL-33 deficiency decreased CD146 expression and alleviated asthma severity. Similarly, CD146 deficiency mitigated EMT and airway remodeling in a murine model of chronic allergic airway inflammation. Furthermore, CD146 expression was significantly elevated in asthma patients. We concluded that IL-33 from HDM extract-treated alveolar epithelial cells stimulated CD146 expression, promoting EMT in airway remodeling in chronic allergic inflammation.