Allergic Airway Inflammation Research Articles

Neural regulation of ILC2s in allergic airway inflammation.

The sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) regulate the effector functions of group 2 innate lymphoid cells (ILC2s) through β2 adrenergic receptor (ADRB2) and nicotinic/muscarinic cholinergic receptor signaling, respectively. To further maintain the critical balance between host-protective and pathogenic type 2 inflammation in the lungs, neuropeptides neuromedin B (NMB) and neuromedin U (NMU) function to suppress or promote ILC2 responses in synergy with IL-33/IL-25, respectively. Additionally, the release of ATP into the extracellular environment in response to cell death caused by challenge to the airway epithelial barrier quickly becomes converted into adenosine, which helps keep the inflammatory response in check by suppressing ILC2 responses. Besides neurotransmitter and neuropeptides derived from other cells, ILC2s further regulate allergic airway inflammation through the production of acetylcholine (ACh) and calcitonin gene-related peptide (CGRP). In this article we review the neuromodulation of ILC2s through cholinergic and adrenergic signaling, neuropeptides, and adenosine and its role in allergic airway inflammation. Furthermore, we discuss the potential clinical utility of targeting these pathways for therapeutic goals and address directions for future research.

Diet-induced obesity worsens allergen-induced type 2/type 17 inflammation in airways by enhancing DUOX1 activation.

More than 50% of people with asthma in the United States are obese, and obesity often worsens symptoms of allergic asthma and impairs response to treatment. Based on previously established roles of the epithelial NADPH oxidase DUOX1 in allergic airway inflammation, we addressed the potential involvement of DUOX1 in altered allergic inflammation in the context of obesity. Intranasal house dust mite (HDM) allergen challenge of subjects with allergic asthma induced rapid secretion of IL-33, then IL-13, into the nasal lumen, responses that were significantly enhanced in obese asthmatic subjects (BMI >30). Induction of diet-induced obesity (DIO) in mice by high-fat diet (HFD) feeding similarly enhanced acute airway responses to intranasal HDM challenge, particularly with respect to secretion of IL-33 and type 2/type 3 cytokines, and this was associated with enhanced epithelial DUOX1 expression and was avoided in DUOX1-deficient mice. DIO also enhanced DUOX1-dependent features of chronic HDM-induced allergic inflammation. Although DUOX1 did not affect overall weight gain by HFD feeding, it contributed to glucose intolerance, suggesting a role in glucose metabolism. However, glucose intolerance induced by short-term HFD feeding, in the absence of adiposity, was not sufficient to alter HDM-induced acute airway responses. DIO was associated with enhanced presence of the adipokine leptin in the airways, and leptin enhanced DUOX1-dependent IL-13 and mucin production in airway epithelial cells. In conclusion, augmented inflammatory airway responses to HDM in obesity are associated with increases in airway epithelial DUOX1, and by increased airway epithelial leptin signaling.

Effects of mesenchymal stem cell-derived nanovesicles in experimental allergic airway inflammation

BackgroundAllergic asthma is associated with airflow obstruction and hyper-responsiveness that arises from airway inflammation and remodeling. Cell therapy with mesenchymal stem cells (MSC) has been shown to attenuate inflammation in asthma models, and similar effects have recently been observed using extracellular vesicles (EV) obtained from these cells. Biologically functional vesicles can also be artificially generated from MSC by extruding cells through membranes to produce EV-mimetic nanovesicles (NV). In this study, we aimed to determine the effects of different MSC-derived vesicles in a murine model of allergic airway inflammation.MethodsEV were obtained through sequential centrifugation of serum-free media conditioned by human bone marrow MSC for 24 h. NV were produced through serial extrusion of the whole cells through filters. Both types of vesicles underwent density gradient purification and were quantified through nanoparticle tracking analysis. C57BL/6 mice were sensitized to ovalbumin (OVA, 8 µg), and then randomly divided into the OVA group (intranasally exposed to 100 µg OVA for 5 days) and control group (exposed to PBS). The mice were then further divided into groups that received 2 × 109 EV or NV (intranasally or intraperitoneally) or PBS immediately following the first OVA exposure.ResultsAdministration of EV and NV reduced cellularity and eosinophilia in bronchoalveolar lavage (BAL) fluid in OVA-sensitized and OVA-exposed mice. In addition, NV treatment resulted in decreased numbers of inflammatory cells within the lung tissue, and this was associated with lower levels of Eotaxin-2 in both BAL fluid and lung tissue. Furthermore, both intranasal and systemic administration of NV were effective in reducing inflammatory cells; however, systemic delivery resulted in a greater reduction of eosinophilia in the lung tissue.ConclusionsTaken together, our results indicate that MSC-derived NV significantly reduce OVA-induced allergic airway inflammation to a level comparable to EV. Thus, cell-derived NV may be a novel EV-mimetic therapeutic candidate for treating allergic diseases such as asthma.

Prenatal LPS Exposure Promotes Allergic Airway Inflammation via Long Coding RNA NONMMUT033452.2, and Protein Binding Partner, Eef1D.

Epidemiological surveys indicate that intrauterine inflammation increases the risk of asthma in offspring. However, the underlying mechanisms remain largely unknown. Previous studies in BALB/c and C57BL/6 mice showed that prenatal exposure to endotoxins prevented allergic airway inflammation in offspring, which is inconsistent with most clinical observations. In this study, we found that prenatal LPS exposure increased airway resistance and total exfoliated cell counts, eosinophils, and IL-4 concentrations in BAL fluid of ovalbumin-sensitized Institute of Cancer Research (ICR) mice. Importantly, long noncoding RNA (lncRNA) NONMMUT033452.2 was upregulated in the lungs of LPS-exposed ICR offspring. Fluorescence in situ hybridization and cytoplasmic and nuclear fraction analyses revealed that this lncRNA was distributed in both the nuclei and cytoplasm of lung and airway epithelial cells, smooth muscle cells, and fibroblasts. Intranasal administration of NONMMUT033452.2 siRNA markedly alleviated allergic airway inflammation in ovalbumin-sensitized ICR mice. In vitro functional experiments demonstrated that overexpression of NONMMUT033452.2 inhibited the proliferation of lung and bronchiolar epithelial cells and promoted oxidative stress. RNA pull-down assays proved that NONMMUT033452.2 could directly bind Eef1D (eukaryotic translation elongation factor 1 delta). Overexpression of NONMMUT033452.2 induced the redistribution of Eef1D and substantially inhibited the expression of its downstream heat shock genes. NONMMUT033452.2 was also involved in the modulation of IL-1, IL-12, and some key molecules related to asthma, including Npr3 (natriuretic peptide receptor 3), Rac1 (Rac family small GTPase 1), and Nr4a3 (nuclear receptor subfamily 4, group A, member 3). Furthermore, the human lncRNA NONHSAT078603.2 was identified as a functional homolog of NONMMUT033452.2. These findings provide new insight into the pathogenic mechanism underlying asthma development.

Oleanolic Acid Acetate Inhibits Mast Cell Activation in Ovalbumin-Induced Allergic Airway Inflammation.

Asthma is a complex, heterogeneous chronic inflammatory airway disease with multiple phenotypes. There has been a great progress in managing asthma, but there are still unmet needs for developing uncontrolled asthma treatments. The present study aimed to determine the effectiveness of oleanolic acid acetate (OAA) from Vigna angularis against allergic airway inflammation and the underlying mechanism of action with a focus on mast cells. To investigate the effect of OAA in allergic airway inflammation, we used the ovalbumin (OVA)-sensitized and challenged mice. To examine allergic airway inflammation associated with immune responses of mast cell activation in vitro, various types of mast cells were used. Systemic and cutaneous anaphylaxis models were used for mast cell-mediated hyper-responsiveness in vivo. OAA reduced OVA-induced airway inflammatory responses such as bronchospasm, increase of immune cell infiltration and serum immunoglobulin E and G1 levels. Especially, OAA decreased the mast cell infiltration, and β-hexosaminidase release as a mast cell activation marker in the bronchoalveolar lavage fluid. OAA inhibited mast cell degranulation in mast cell line (RBL-2H3) and primary cells (rat peritoneal mast cell and mouse bone marrow-derived mast cell). Mechanistically, OAA suppressed intracellular signaling pathways including the phosphorylation of phospholipase Cγ and nuclear factor-κB, resulting from the suppression of intracellular calcium influx and pro-inflammatory cytokine expression. Further, oral administration of OAA attenuated mast cell-mediated systemic and cutaneous anaphylaxis. Our study showed that OAA can inhibit mast cell-mediated allergic reaction. Consequently, the application of OAA to mast cells for the allergic airway inflammation facilitate a new direction of treating allergic asthma.

The HDAC10 instructs macrophage M2 program via deacetylation of STAT3 and promotes allergic airway inflammation.

Background: Perturbation of macrophage homeostasis is one of the key mechanisms of airway inflammation in asthma. However, the exact mechanisms remain poorly understood. Objectives: We sought to examine the role of histone deacetylase (HDAC) 10 as an epigenetic regulator that governs macrophage M2 program and promotes airway inflammation in asthma, and to elucidate the underlying mechanisms. Methods: Peripheral blood and airway biopsies were obtained from healthy individuals and asthmatic patients. Asthma was induced by exposure to allergen in mice with myeloid-specific deletion of Hdac10 (Hdac10fl/fl-LysMCre) mice. HDAC10 inhibitor Salvianolic acid B (SAB), STAT3 selective agonist Colivelin, and the specific PI3K/Akt activator 1,3-Dicaffeoylquinic acid (DA) were also used in asthmatic mice. For cell studies, THP1 cells, primary mouse bone marrow derived macrophage (BMDMs) were used and related signaling pathways was investigated. Results: HDAC10 expression was highly expressed by macrophages and promoted M2 macrophage activation and airway inflammation in asthmatic patients and mice. Hdac10fl/fl-LysMCre mice were protected from airway inflammation in experimental asthma model. Hdac10 deficiency significantly attenuated STAT3 expression and decreased M2 macrophage polarization following allergen exposure. Mechanistically, HDAC10 directly binds STAT3 for deacetylation in macrophages, by which it promotes STAT3 expression and activates the macrophage M2 program. Importantly, we identified SAB as a HDAC10 inhibitor that had protective effects against airway inflammation in mice. Conclusions: Our results revealed that HDAC10-STAT3 interaction governs macrophage polarization to promote airway inflammation in asthma, implicating HDAC10 as a therapeutic target.

Calcium ionophore-activated platelets induce eosinophil extracellular trap formation

BackgroundPlatelets play a modulatory role in inflammatory response by secreting a vast array of granules and disintegrating into membrane-bound microparticles upon activation. The interplay between eosinophils and platelets is postulated to be implicated in the pathology of allergic airway inflammation. In this study, we investigated whether activated platelets can induce eosinophil extracellular trap (EET) formation, a cellular process by which activated eosinophils release net-like DNA fibers. MethodsPlatelets were stimulated with the calcium ionophore, A23187, and the platelet agonists, thrombin and adenosine diphosphate (ADP). Platelet cultures were fractionated into conditioned medium (CM) and pellet, which were then overlaid on eosinophils to examine EET formation. ResultsThe CM and pellet from A23187-activated platelets stimulated eosinophils to generate EET, whereas those from thrombin- or ADP-activated platelets failed to induce such generation. The EET-inducing activity of the A23187-activated platelet culture was linearly proportional to the number of activated platelets. Interestingly, while EET formation induced by the direct stimulation of eosinophils with A23187 was NADPH oxidase (NOX)-dependent, EET formation induced by A23187-activated platelets was NOX-independent and significantly inhibited by necroptosis pathway inhibitors. ConclusionsActivated platelets and their products may induce EET formation, thereby potentiating their role in eosinophilic airway inflammation.

Structures of the Inhibitory Receptor Siglec-8 in Complex with a High-Affinity Sialoside Analogue and a Therapeutic Antibody.

Human sialic acid binding immunoglobulin-like lectin-8 (Siglec-8) is an inhibitory receptor that triggers eosinophil apoptosis and can inhibit mast cell degranulation when engaged by specific monoclonal antibodies (mAbs) or sialylated ligands. Thus, Siglec-8 has emerged as a critical negative regulator of inflammatory responses in diverse diseases, such as allergic airway inflammation. Herein, we have deciphered the molecular recognition features of the interaction of Siglec-8 with the mAb lirentelimab (2C4, under clinical development) and with a sialoside mimetic with the potential to suppress mast cell degranulation. The three-dimensional structure of Siglec-8 and the fragment antigen binding (Fab) portion of the anti-Siglec-8 mAb 2C4, solved by X-ray crystallography, reveal that 2C4 binds close to the carbohydrate recognition domain (V-type Ig domain) on Siglec-8. We have also deduced the binding mode of a high-affinity analogue of its sialic acid ligand (9-N-napthylsufonimide-Neu5Ac, NSANeuAc) using a combination of NMR spectroscopy and X-ray crystallography. Our results show that the sialoside ring of NSANeuAc binds to the canonical sialyl binding pocket of the Siglec receptor family and that the high affinity arises from the accommodation of the NSA aromatic group in a nearby hydrophobic patch formed by the N-terminal tail and the unique G-G' loop. The results reveal the basis for the observed high affinity of this ligand and provide clues for the rational design of the next generation of Siglec-8 inhibitors. Additionally, the specific interactions between Siglec-8 and the N-linked glycans present on the high-affinity receptor FcεRIα have also been explored by NMR.

Effect of Torilis leptophylla on blood total leukocyte count and differential leukocyte count in asthmatic mice

Background: Chronic inflammation, mucus hypersecretion and airway blockage are the characteristics of asthma. Current treatments of asthma are effective but cause adverse effects on their long term use. This research was designed to explore anti-inflammatory effect of Torilis leptophylla (T. leptophylla) on allergic inflammation of airways by estimation of blood total leukocyte count (TLC) and differential leukocyte count (DLC) to compare its effect with a standard drug in an animal model.
 Materials and methods: This experimental study was carried out in Pharmacology Department, University of Health Sciences, Lahore. A total of 48 healthy, adult, male BALB/c mice were randomly divided into six groups. Group I (control), group II (diseased); groups III, IV and V were given 100, 200, 400 mg/kg T. leptophylla methanolic extract (TLM) respectively, and Group VI treated with standard drug monteleukast. Airway inflammation was induced in all groups with ovalbumin except control group. On day 28, cardiac puncture was done to collect the blood and TLC and DLC (lymphocytes, neutrophils, eosinophils and monocytes) were measured in blood. All the data was interpreted as mean ± SD. SPSS 20 was used to carry out statistical analysis.
 Results: T. leptophylla extract resulted in significant (p-value ≤ 0.05) decrease of TLC and DLC in blood. T. leptophylla cause 59-67% decrease in TLC, 67-80% decrease in lymphocytes, 69 - 72% decrease in neutrophils, and 45-51.7% decrease in eosinophils
 Conclusion: In current study T. leptophylla successfully treated inflammation in asthmatic mice by reducing proportion of inflammatory cells.

Complete Genome Sequence of Lactobacillus johnsonii MR1, Isolated from a BALB/c Mouse Cecum.

Lactobacillus johnsonii strain MR1, which was isolated from the cecum of a BALB/cJ mouse in an airway allergy model, can decrease allergic airway inflammation in the model upon oral administration. Long-read sequencing of this isolate, which was performed using a MinION sequencer, yielded a single, closed genome of 1,953,837 bp, with a GC content of 34.67%.

Intranasal administration of Acinetobacter lwoffii in a murine model of asthma induces IL-6-mediated protection associated with cecal microbiota changes.

Early-life exposure to certain environmental bacteria including Acinetobacter lwoffii (AL) has been implicated in protection from chronic inflammatory diseases including asthma later in life. However, the underlying mechanisms at the immune-microbe interface remain largely unknown. The effects of repeated intranasal AL exposure on local and systemic innate immune responses were investigated in wild-type and Il6-/- , Il10-/- , and Il17-/- mice exposed to ovalbumin-induced allergic airway inflammation. Those investigations were expanded by microbiome analyses. To assess for AL-associated changes in gene expression, the picture arising from animal data was supplemented by in vitro experiments of macrophage and T-cell responses, yielding expression and epigenetic data. The asthma preventive effect of AL was confirmed in the lung. Repeated intranasal AL administration triggered a proinflammatory immune response particularly characterized by elevated levels of IL-6, and consequently, IL-6 induced IL-10 production in CD4+ T-cells. Both IL-6 and IL-10, but not IL-17, were required for asthma protection. AL had a profound impact on the gene regulatory landscape of CD4+ T-cells which could be largely recapitulated by recombinant IL-6. AL administration also induced marked changes in the gastrointestinal microbiome but not in the lung microbiome. By comparing the effects on the microbiota according to mouse genotype and AL-treatment status, we have identified microbial taxa that were associated with either disease protection or activity. These experiments provide a novel mechanism of Acinetobacter lwoffii-induced asthma protection operating through IL-6-mediated epigenetic activation of IL-10 production and with associated effects on the intestinal microbiome.

Dietary digestible carbohydrates are associated with higher prevalence of asthma in humans and with aggravated lung allergic inflammation in mice.

Dietary carbohydrates and fats are intrinsically correlated within the habitual diet. We aimed to disentangle the associations of starch and sucrose from those of fat, in relation to allergic sensitization, asthma and rhinoconjuctivitis prevalence in humans, and to investigate underlying mechanisms using murine models. Epidemiological data from participants of two German birth cohorts (age 15) were used in logistic regression analyses testing cross-sectional associations of starch and sucrose (and their main dietary sources) with aeroallergen sensitization, asthma and rhinoconjunctivitis, adjusting for correlated fats (saturated, monounsaturated, omega-6 and omega-3 polyunsaturated) and other covariates. For mechanistic insights, murine models of aeroallergen-induced allergic airway inflammation (AAI) fed with a low-fat-high-sucrose or -high-starch versus a high-fat diet were used to characterize and quantify disease development. Metabolic and physiologic parameters were used to track outcomes of dietary interventions and cellular and molecular responses to monitor the development of AAI. Oxidative stress biomarkers were measured in murine sera or lung homogenates. We demonstrate a direct association of dietary sucrose with asthma prevalence in males, while starch was associated with higher asthma prevalence in females. In mice, high-carbohydrate feeding, despite scant metabolic effects, aggravated AAI compared to high-fat in both sexes, as displayed by humoral response, mucus hypersecretion, lung inflammatory cell infiltration and TH 2-TH 17 profiles. Compared to high-fat, high-carbohydrate intake was associated with increased pulmonary oxidative stress, signals of metabolic switch to glycolysis and decreased systemic anti-oxidative capacity. High consumption of digestible carbohydrates is associated with an increased prevalence of asthma in humans and aggravated lung allergic inflammation in mice, involving oxidative stress-related mechanisms.

Artemisia gmelinii Extract Alleviates Allergic Airway Inflammation via Balancing TH1/TH2 Homeostasis and Inhibiting Mast Cell Degranulation.

A new terminology "combined allergic rhinitis and asthma syndrome (CARAS)" was introduced to describe patients suffering from both allergic rhinitis (AR) and asthma. The pathogenesis of allergic airway inflammation has been well known, with the main contribution of TH1/TH2 imbalance and mast cell degranulation. Artemisia gmelinii has been used as an herbal medicine with its hepaprotective, anti-inflammatory, and antioxidant properties. In this study, the effect of A. gmelinii extracts (AGE) on the ovalbumin (OVA)-induced CARAS mouse model was investigated. AGE administration significantly alleviated the nasal rubbing and sneezing, markedly down-regulated both OVA-specific IgE, IgG1, and histamine levels, and up-regulated OVA-specific IgG2a in serum. The altered histology of nasal and lung tissues of CARAS mice was effectively ameliorated by AGE. The AGE treatment group showed markedly increased levels of the TH1 cytokine interleukin (IL)-12 and TH1 transcription factor T-bet. In contrast, the levels of the TH2 cytokines, including IL-4, IL-5, IL-13, and the TH2 transcription factor GATA-3, were notably suppressed by AGE. Moreover, AGE effectively prevented mast cell degranulation in vitro and mast cell infiltration in lung tissues in vivo. Based on these results, we suggest that AGE could be a potential therapeutic agent in OVA-induced CARAS by virtue of its role in balancing the TH1/TH2 homeostasis and inhibiting the mast cell degranulation.

The anti-asthmatic potential of Rho-kinase inhibitor hydroxyfasudil in the model of experimentally induced allergic airway inflammation

ObjectiveThis experimental study evaluated the anti-asthmatic potential of the Rho-kinase inhibitor hydroxyfasudil in the settings of allergen-induced allergen-induced experimental asthma. MethodsChronic allergic airway inflammation was caused by 28 days-sensitisation of guinea pigs with ovalbumin (OVA). Hydroxyfasudil was administered intraperitoneally in two doses for the last two weeks (1 mg/kg b.w.; 10 mg/kg b.w.). The degree of allergic inflammation was determined based on concentrations of inflammatory Th2 cytokines (IL-4, IL-13), Th1 cytokines (TNF-α and IFN-γ) in the lung homogenate and leukocyte count in the bronchoalveolar lavage fluid (BALF). The markers of remodelling and fibrosis, the growth factors (TGF-β1, EGF), EGF receptor, collagen type III and V were estimated in lung homogenate. The changes in specific airway resistance (sRaw) were used as an in vivo bronchial hyperreactivity parameter. ResultsHydroxyfasudil administration at both doses significantly reduced sRaw after a week of therapy. We observed a decline of IL-13, TNF-α and IFN-γ in lung homogenate and a lower presence of lymphocytes in BALF after 14 days of hydroxyfasudil administration at both tested doses. Hydroxyfasudil 14 days-treatment at both doses effectively reduced the concentrations of TGF-β1, EGF receptors, collagen type III and V in BALF and modulated EGF levels. ConclusionsThese findings indicate that RhoA/Rho-kinase is involved in the pathophysiology of allergic airway inflammation and suggest that Rho-kinase inhibitor hydroxyfasudil has therapeutic potential for asthma management.

Fingolimod attenuates ovalbumin-induced airway inflammation via inhibiting MAPK/ERK signaling in mice.

The current study was designed to investigate the potential anti-inflammatory and antioxidant effects of fingolimod against Ovalbumin (Ova)-induced allergic airway inflammation compared to dexamethasone. Fingolimod was given (0.5 mg/kg/day, p.o.) for sensitized mice 1 hbefore Ova challenge from Days 19 to 24. Fingolimod significantly inhibited Ova-induced elevation of inflammatory cells and eosinophils numbers in bronchoalveolar lavage fluid(BALF) and reduced concentrations of immunoglobulin E in serum and of sphingosine-1-phosphate, interleukin(IL)-4, and IL-13 in BALF. Fingolimod inhibited microvascular leakage and edema as reflected by the decreased lung/body weight index. These findings were supported by histopathological examination results showing that fingolimod substantially decreased perivascular edema and inflammatory cell infiltration. Fingolimod also attenuated Ova-induced oxidative stress as evidenced by decreased malondialdehyde concentration along with increasing concentrations of reduced glutathione and superoxide dismutase in lung tissues. Fingolimod also significantly decreased monocyte chemoattractant protein-1(MCP-1), p-ERK,and p-P38 in lung tissues of Ova-challenged mice. In conclusion, the current study demonstrated the anti-inflammatory and antioxidant effects of fingolimod in allergic airway inflammation that might be associated with the downregulation of mitogen activated kinases signaling to decrease T helper 2 cytokine secretion (IL-4 and IL-13) and MCP-1 expression, along with the inhibition of oxidative stress.

β-Arrestin-biased proteinase-activated receptor-2 antagonist C781 limits allergen-induced airway hyperresponsiveness and inflammation.

Asthma is a heterogenous disease strongly associated with inflammation that has many different causes and triggers. Current asthma treatments target symptoms such as bronchoconstriction and airway inflammation. Despite recent advances in biological therapies, there remains a need for new classes of therapeutic agents with novel, upstream targets. The proteinase-activated receptor-2 (PAR2) has long been implicated in allergic airway inflammation and asthma and it remains an intriguing target for novel therapies. Here, we describe the actions of C781, a newly developed low MW PAR2 biased antagonist, in vitro and in vivo in the context of acute allergen exposure. A human bronchial epithelial cell line expressing PAR2 (16HBE14o- cells) was used to evaluate the modulation in vitro, by C781, of physiological responses to PAR2 activation and downstream β-arrestin/MAPK and Gq/Ca2+ signalling. Acute Alternaria alternata sensitized and challenged mice were used to evaluate C781 as a prophylactically administered modulator of airway hyperresponsiveness, inflammation and mucus overproduction in vivo. C781 reduced in vitro physiological signalling in response to ligand and proteinase activation. C781 effectively antagonized β-arrestin/MAPK signalling without significant effect on Gq/Ca2+ signalling in vitro. Given prophylactically, C781 modulated airway hyperresponsiveness, airway inflammation and mucus overproduction of the small airways in an acute allergen-challenged mouse model. Our work demonstrates the first biased PAR2 antagonist for β-arrestin/MAPK signalling. C781 is efficacious as a prophylactic treatment for allergen-induced airway hyperresponsiveness and inflammation in mice. It exemplifies a key pharmacophore for PAR2 that can be optimized for clinical development.

Targeting epithelial cell-derived TWIST1 alleviates allergic asthma

It is well known that the T Helper (Th)2 bias plays a critical role in allergic asthma. Whereas the Th2 bias is maintained in the local tissues is uncertain. IL-33 is vital for the development of the Th2 polarization. TWIST-1 has an effect on regulating cellular functions. The aberrant activation of RAS sustains certain cellular activities. The aim of this study is to study the role of the interaction between activation of TWIST1 and RAS in inducing and maintaining Th2 polarization in allergic asthma. The epithelial cells of the airways (AEC) were isolated from the broncho-alveolar lavage fluids in patients with asthma. The mediators involved in the over-expression of IL-33 were determined by RNA sequencing. A mouse model was established to test the role of TWIST1 and RAS in developing allergic asthma. We observed a strong expression of TWIST1 in patients with allergic asthma that showed a positive correlation with asthmatic responses. TWIST1 favored the expression of the IL-33 in the AEC. Twist1-deficient AEC-carrying mice did not induce Th2 polarization in the airways. The expression TWIST1 in AECs was positively associated with RAS activation in AECs in patients with allergic asthma. The interaction between RAS and TWIST1 in AECs sustained airway allergic inflammation. Inhibition of TWIST1 or RAS prevented asthma-like inflammation in the mouse airways. In summary, the interaction between TWIST1 and RAS induces and maintains IL-33 expression in AECs to facilitate allergic inflammation in the respiratory tract. Inhibition of TWIST1 or RAS can prevent experimental allergic asthma.

Characterization of sex-related differences in allergen house dust mite-challenged airway inflammation, in two different strains of mice

Biological sex impacts disease prevalence, severity and response to therapy in asthma, however preclinical studies often use only one sex in murine models. Here, we detail sex-related differences in immune responses using a house dust mite (HDM)-challenge model of acute airway inflammation, in adult mice of two different strains (BALB/c and C57BL/6NJ). Female and male mice were challenged (intranasally) with HDM extract (~ 25 μg) for 2 weeks (N = 10 per group). Increase in serum HDM-specific IgE showed a female bias, which was statistically significant in BALB/c mice. We compared naïve and HDM-challenged mice to define immune responses in the lungs by assessing leukocyte accumulation in the bronchoalveolar lavage fluid (BALF), and profiling the abundance of 29 different cytokines in BALF and lung tissue lysates. Our results demonstrate specific sex-related and strain-dependent differences in airway inflammation. For example, HDM-driven accumulation of neutrophils, eosinophils and macrophages were significantly higher in females compared to males, in BALB/c mice. In contrast, HDM-mediated eosinophil accumulation was higher in males compared to females, in C57BL/6NJ mice. Differences in lung cytokine profiles indicated that HDM drives a T-helper (Th)17-biased response with higher IL-17 levels in female BALB/c mice compared to males, whereas female C57BL/6NJ mice elicit a mixed Th1/Th2-skewed response. Male mice of both strains showed higher levels of specific Th2-skewed cytokines, such as IL-21, IL-25 and IL-9, in response to HDM. Overall, this study details sex dimorphism in HDM-mediated airway inflammation in mice, which will be a valuable resource for preclinical studies in allergic airway inflammation and asthma.

Dasatinib attenuates airway inflammation of asthma exacerbation in mice induced by house dust mites and dsRNA

Asthma exacerbation is a significant clinical problem that causes resistance to corticosteroid therapy and elevated hospitalization risk. Src family kinases (SFKs) contribute to various steps of the immune response, such as airway inflammation in viral or bacterial infections and allergic asthma. Therefore, we determined the effects of dasatinib (DAS), a typical Src inhibitor, on a murine asthma exacerbation model induced by house dust mites (HDM) and synthetic analog of double-stranded RNA, poly(I:C). A/J mice were sensitized to intrapreneurial HDM twice every seven days and challenged with intranasal HDM once every second day for a total of six exposures, and/or exposed to poly(I:C) twice daily for three consecutive days. Drug treatments were performed twice daily for three days, starting one day after the last HDM challenge or 2 h before each poly(I:C) exposure. DAS improved poly(I:C)-induced acute inflammation dose-dependently. Both DAS and fluticasone propionate (FP) attenuated HDM-induced allergic airway inflammation. However, in HDM and poly(I:C) induced-asthma exacerbated mice, DAS significantly improved inflammatory cells in bronchoalveolar lavage fluid and histological changes in the lungs, whereas FP did not. Therefore, SFKs are important targets for controlling severe asthma refractory to conventional therapies.

Nebulized Mycobacterium vaccae protects against asthma by attenuating the imbalance of IRF4/IRF8 expression in dendritic cells

Objective: To assess the effects of nebulized inhaled Mycobacterium vaccae on allergic airway inflammation, airway hyperresponsiveness, and Th1/Th2 cell imbalance in mice with ovalbumin (OVA)-induced asthma. Methods: Mice received OVA sensitization and challenge for establishment of the asthmatic model. For intervention, mice received Mycobacterium vaccae nebulization once every other day from the first day of sensitization to the day before challenge. After challenge, pulmonary histological analysis and airway responsiveness measurement were performed. In addition, Th1/Th2 cytokines and OVA-specific IgE levels in bronchoalveolar lavage fluid were measured by ELISA. Th1/Th2 subset ratios and the expression of interferon-regulatory factor 4 (IRF4), IRF8 and Toll-like receptor 4 (TLR4) in dendritic cells were evaluated by flow cytometry. Results: Severe inflammatory infiltration and airway hyperresponsiveness were observed in OVA-induced asthmatic mice. Asthmatic mice showed higher Th2 cytokine concentration and increased percentage of Th2 cells, along with lower Th1 cytokine concentration and reduced percentage of Th1 cells compared with the normal control. Moreover, an imbalance of IRF4+ and IRF8+ in dendritic cells was found in asthmatic mice. Nebulized inhaled Mycobacterium vaccae reduced airway hyperresponsiveness and inflammation in OVA-induced asthmatic mice. In addition, nebulized inhaled Mycobacterium vaccae enhanced TLR4 and IRF8 expression, and alleviated the imbalance of Th1/Th2 as well as IRF4+ and IRF8+ in dendritic cells. Conclusions: Nebulized inhaled Mycobacterium vaccae protects against asthma by alleviating the imbalance of Th1/Th2 and IRF4/ IRF8 in OVA-induced asthmatic mice.