Mouse Models of Asthma

Birch pollen allergen-induced dsDNA release activates cGAS-STING signaling and type 2 immune response in mice

Detecting cytoplasmic or extracellular DNA from host or pathogen origin by DNA sensor cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) triggers immune responses with secretion of type I interferons and inflammatory cytokines. However, STING agonists function as type-2 adjuvant promoting allergic asthma. Here, we asked how cGAS/STING signaling pathway influences allergen-induced type-2 immune responses in models of allergic airway diseases induced by birch pollen extract, house dust mite, or ovalbumin plus Alum. We report increased extracellular dsDNA in the airways, together with cGAS and STING gene expression, following allergen challenge in these models, correlating dsDNA and type-2 cytokine IL-4, IL-5, and IL-13 release. Allergen-induced type-2 immune responses were reduced in cGAS- or STING-deficient mice. Further, blocking cGAS function with the specific inhibitor RU.521 protected mice from birch pollen allergen-induced airway inflammation and type-2 immune responses. Thus, DNA sensing by cGAS contributes to type-2 immune responses and may represent a therapeutic target for allergic lung inflammation.

Innate Immunity and Asthma Exacerbations: Insights From Human Models

Asthma is a common chronic respiratory disease characterized by the presence of airway inflammation, airway hyperresponsiveness, and mucus hypersecretion. Repeated asthma exacerbations can lead to progressive airway remodeling and irreversible airflow obstruction. Thus, understanding and preventing asthma exacerbations are of paramount importance. Although multiple endotypes exist, asthma is most often driven by type 2 airway inflammation. New therapies that target specific type 2 mediators have been shown to reduce the frequency of asthma exacerbations but are incompletely effective in a significant number of asthmatics. Furthermore, it remains unknown whether current treatments lead to sustained changes in the airway or if targeting additional pathways may be necessary to achieve asthma remission. Activation of innate immunity is the initial event in the inflammatory sequence that occurs during an asthma exacerbation. However, there continue to be critical gaps in our understanding of the innate immune response to asthma exacerbating factors. In this review, we summarize the current understanding of the role of innate immunity in asthma exacerbations and the methods used to study them. We also identify potential novel therapeutic targets for asthma and future areas for investigation.

IL-33 released during challenge phase regulates allergic asthma in an age-dependent way

Epithelial-derived cytokines, especially type 2 alarmins (TSLP, IL-25, and IL-33), have emerged as critical mediators of type 2 inflammation. IL-33 attracts more interest for its strong association with allergic asthma, especially in childhood asthma. However, the age-dependent role of IL-33 to the development of allergic asthma remains elusive. Here, using OVA-induced allergic asthma model in neonatal and adult mice, we report that IL-33 is the most important alarmin in neonatal lung both at steady state or inflammation. The deficiency of IL-33/ST2 abrogated the development of allergic asthma only in neonates, whereas in adults the effect was limited. Interestingly, the deficiency of IL-33/ST2 equally dampened the ILC2 responses in both neonatal and adult models. However, the effect of IL-33/ST2 deficiency on Th2 responses is age-dependent, which is only blocked in neonates. Furthermore, IL-33/ST2 signaling is dispensable for OVA sensitization. Following OVA challenge in adults, the deficiency of IL-33/ST2 results in compensational more TSLP, which in turn recruits and activates lung DCs and boosts Th2 responses. The enriched γδ T17 cells in IL-33/ST2 deficient neonatal lung suppress the expression of type 2 alarmins, CCL20 and GM-CSF via IL-17A, thus might confer the inhibition of allergic asthma. Finally, on the basis of IL-33 deficiency, the additive protective effects of TSLP blocking is much more pronounced than IL-25 blocking in adults. Our studies demonstrate that the role of IL-33 for ILC2 and Th2 responses varies among ages in OVA models and indicate that the factor of age should be considered for intervention of asthma.

Unilateral Bleomycin-induced Interstitial Pneumonitis Mouse Model With Both a Healthy and a Diseased Lung

BACKGROUND/AIM

A standard mouse model of pulmonary fibrosis has been created by intratracheal or intraperitoneal administration of bleomycin. However, a difficulty presented by this traditional method is its high mortality rate of more than 50% after bleomycin administration. In this study, we aimed to establish a unilateral lung disease model and to assess its feasibility and usefulness.

MATERIALS AND METHODS

After 6-week-old C57BL/6 mice were anesthetized, a 1.7Fr microcatheter was advanced into the trachea using an otoscope. Then, 1.0 mg/kg of bleomycin was injected into bilateral lung at the trachea (n=13) or unilateral lung (n=14) after advancing the microcatheter to the left main bronchus under fluoroscopy. Body weight change and survival of bilateral and unilateral lung disease group mice at day 28 were compared using Mann-Whitney and log-rank tests. Lungs were extracted and evaluated using Masson trichrome staining.

RESULTS

Body weights decreased 75.7%±14.0% in the bilateral lung disease group, but were greater, 94.1%±11.4%, in the unilateral lung disease group (p=0.03). Overall survival rates at day 28 were 30.8% and 85.7% in the bilateral and unilateral lung disease groups, respectively. Survival was significantly better in the unilateral lung disease model (p=0.01). Histological evaluation confirmed collagen deposition only in the bleomycin injected lung in the unilateral lung disease model.

CONCLUSION

Establishing both a healthy and a diseased lung in the same individual model was feasible, achieving lessened body weight loss and more favorable survival. This technique allows for a more efficacious research design, where both the efficacy and adverse effects of a pharmaceutical agent can be evaluated in a single animal.

Wild-Mouse-Derived Gut Microbiome Transplantation in Laboratory Mice Partly Alleviates House-Dust-Mite-Induced Allergic Airway Inflammation

Laboratory mice are instrumental for preclinical research but there are serious concerns that the use of a clean standardized environment for specific-pathogen-free (SPF) mice results in poor bench-to-bedside translation due to their immature immune system. The aim of the present study was to test the importance of the gut microbiota in wild vs. SPF mice for evaluating host immune responses in a house-dust-mite-induced allergic airway inflammation model without the influence of pathogens. The wild mouse microbiome reduced histopathological changes and TNF-α in the lungs and serum when transplanted to microbiota-depleted mice compared to mice transplanted with the microbiome from SPF mice. Moreover, the colonic gene expression of Gata3 was significantly lower in the wild microbiome-associated mice, whereas Muc1 was more highly expressed in both the ileum and colon. Intestinal microbiome and metabolomic analyses revealed distinct profiles associated with the wild-derived microbiome. The wild-mouse microbiome thus partly reduced sensitivity to house-dust-mite-induced allergic airway inflammation compared to the SPF mouse microbiome, and preclinical studies using this model should consider using both 'dirty' rewilded and SPF mice for testing new therapeutic compounds due to the significant effects of their respective microbiomes and derived metabolites on host immune responses.

Adjuvant-independent airway sensitization and infection mouse models leading to allergic asthma

Asthma is a chronic respiratory disease of global importance. Mouse models of allergic asthma have been instrumental in advancing research and novel therapeutic strategies for patients. The application of relevant allergens and physiological routes of exposure in such models has led to valuable insights into the complexities of asthma onset and development as well as key disease mechanisms. Furthermore, environmental microbial exposures and infections have been shown to play a fundamental part in asthma pathogenesis and alter disease outcome. In this review, we delve into physiological mouse models of allergic asthma and explore literature reports on most significant interplays between microbial infections and asthma development with relevance to human disease.

Experimental Insights on the Use of Secukinumab and Magnolol in Acute Respiratory Diseases in Mice

This study investigates the combined treatment of secukinumab (SECU) and magnolol (MAGN) in a mouse model of LPS-induced ALI overlapped with allergic pulmonary inflammation, aiming to better understand the mechanism behind this pathology and to assess the therapeutic potential of this novel approach in addressing the severity of ALI. The combined treatment reveals intricate immunomodulatory effects. Both treatments inhibit IL-17 and promote M2 macrophage polarization, which enhances anti-inflammatory cytokine production such as IL-4, IL-5, IL-10, and IL-13, crucial for lung repair and inflammation resolution. However, the combination treatment exacerbates allergic responses and increases OVA-specific IgE, potentially worsening ALI outcomes. MAGN pretreatment alone demonstrates higher potency in reducing neutrophils and enhancing IFN-γ, suggesting its potential in mitigating severe asthma symptoms and modulating immune responses. The study highlights the need for careful consideration in therapeutic applications due to the combination treatment's inability to reduce IL-6 and its potential to exacerbate allergic inflammation. Elevated IL-6 levels correlate with worsened oxygenation and increased mortality in ALI patients, underscoring its critical role in disease severity. These findings offer valuable insights for the advancement of precision medicine within the realm of respiratory illnesses, emphasizing the importance of tailored therapeutic strategies.

A single infusion of engineered long-lived and multifunctional T cells confers durable remission of asthma in mice

Asthma, the most prevalent respiratory disease, affects more than 300 million people and causes more than 250,000 deaths annually. Type 2-high asthma is characterized by interleukin (IL)-5-driven eosinophilia, along with airway inflammation and remodeling caused by IL-4 and IL-13. Here we utilize IL-5 as the targeting domain and deplete BCOR and ZC3H12A to engineer long-lived chimeric antigen receptor (CAR) T cells that can eradicate eosinophils. We call these cells immortal-like and functional IL-5 CAR T cells (5TIF) cells. 5TIF cells were further modified to secrete an IL-4 mutein that blocks IL-4 and IL-13 signaling, designated as 5TIF4 cells. In asthma models, a single infusion of 5TIF4 cells in fully immunocompetent mice, without any conditioning regimen, led to sustained repression of lung inflammation and alleviation of asthmatic symptoms. These data show that asthma, a common chronic disease, can be pushed into long-term remission with a single dose of long-lived CAR T cells.

Developmental changes in lung function of mice are independent of sex as a biological variable

Pulmonary function testing (PFT) in mice includes biomechanical assessment of lung function relevant to physiology in health and its alteration in disease, hence, it is frequently used in preclinical modeling of human lung pathologies. Despite numerous reports of PFT in mice of various ages, there is a lack of reference data for developing mice collected using consistent methods. Therefore, we profiled PFTs in male and female C57BL/6J mice from 2 to 23 wk of age, providing reference values for age- and sex-dependent changes in mouse lung biomechanics during development and young adulthood. Although males and females have similar weights at birth, females weigh significantly less than males after 5 wk of age (P < 0.001) with largest weight gain observed between 3 and 8 wk in females and 3 and 13 wk in males, after which weight continued to increase more slowly up to 23 wk of age. Lung function parameters including static compliance and inspiratory capacity also increased rapidly between 3 and 8 wk in female and male mice, with male mice having significantly greater static compliance and inspiratory capacity than female mice (P < 0.001). Although these parameters appear higher in males at a given age, allometric scaling showed that static compliance and inspiratory compliance were comparable between the two sexes. This suggests that differences in measurements of lung function are likely body weight-based rather than sex-based. We expect these data to facilitate future lung disease research by filling a critical knowledge gap in our field.NEW & NOTEWORTHY This study provides reference values for changes in mouse lung biomechanics from 2 to 23 wk of age. There are rapid developmental changes in lung structure and function of male and female mice between the ages of 3 and 8 wk. Male mice become noticeably heavier than female mice at or about 5 wk of age. We identified that differences in normal lung function measurements are likely weight-based, not sex-based.

Targeting Common Inflammatory Mediators in Experimental Severe Asthma and Acute Lung Injury

Neutrophils, known to be mobilized and activated in high amounts through Il-17 stimulation, are a key factor for clinical manifestation and imbalance of redox systems favoring a dominant oxidative state in both severe asthma and acute lung injury (f). The aim of this study was to evaluate in mice, the effect of Secukinumab (SECU) in a model of ovalbumin-induced asthma exacerbated with LPS administration to induce ALI, compared to dexamethasone (DEXA), already known for its benefit in both asthma and ALI. Results on cytokine levels for specific Th1, Th2 and Th17 revealed an interplay of immune responses. For Th1 effector cytokines in BALF, DEXA treatment increased TNF-α levels, but TNF-α was not modified by SECU; DEXA and SECU significantly decreased IFN-γ and IL-6 levels. For typical Th2 cytokines, DEXA significantly increased Il-4, Il-5 and Il-13 levels, while SECU significantly inhibited Il-5 levels. Both SECU and DEXA significantly decreased Il-17 levels. Cytokine level changes in lung tissue homogenate were partly similar to BALF cytokines. Conclusion: in addition to DEXA, SECU possesses the ability to modulate inflammatory cytokine release and to decrease Th17 responses in ALI overlapped on exacerbated asthma in mice.

Aluminum hydroxide nanoparticle adjuvants can reduce the inflammatory response more efficiently in a mouse model of allergic asthma than traditional aluminum hydroxide adjuvants

Traditional aluminum hydroxide is widely used as a vaccine adjuvant. Despite its favorable safety profile, it can cause an inflammatory response at the injection sites. However, multiple studies have shown that aluminum hydroxide nanoparticles have more potent adjuvant activity than their traditional aluminum hydroxide counterparts as antigen carriers; it has also been found that the local inflammation caused by aluminum hydroxide nanoparticle adjuvants is milder than that of other adjuvants. The aim of the present study was to compare the degree of inflammatory response between the aluminum hydroxide nanoparticle adjuvants and the traditional aluminum hydroxide adjuvants in the desensitization treatment of a mouse model of house dust mite (HDM)-induced allergic asthma. Mice were sensitized intraperitoneally with HDM. Subcutaneous desensitization was performed with PBS, traditional aluminum hydroxide adjuvants and aluminum hydroxide nanoparticle adjuvants. The mice were challenged and subsequently euthanized. The skin tissue at the local injection sites was assessed and specific indices were measured, such as the response of specific immunoglobulins, the airway hyper-responsiveness (AHR), and the inflammation in the bronchoalveolar lavage and lung tissues. Early hypersensitivity responses were suppressed in mice treated with subcutaneous immunotherapy (SCIT). Both traditional aluminum hydroxide-SCIT and aluminum hydroxide nanoparticle-SCIT could inhibit AHR. However, aluminum hydroxide nanoparticle-SCIT was able to significantly inhibit the secretion of eosinophils in the lung tissue and the production of type 2 cytokine Interleukin (IL)-5 in blood compared with the corresponding effects noted by traditional aluminum hydroxide adjuvants. Moreover, the aluminum hydroxide nanoparticle group reduced the inflammatory response at the local injection site. Collectively, the data indicated that allergen-specific immunotherapy using aluminum hydroxide nanoparticle adjuvants reduces lung and local inflammation compared with traditional aluminum hydroxide adjuvants.

Neural Mechanisms Underlying the Coughing Reflex

Breathing is an intrinsic natural behavior and physiological process that maintains life. The rhythmic exchange of gases regulates the delicate balance of chemical constituents within an organism throughout its lifespan. However, chronic airway diseases, including asthma and chronic obstructive pulmonary disease, affect millions of people worldwide. Pathological airway conditions can disrupt respiration, causing asphyxia, cardiac arrest, and potential death. The innervation of the respiratory tract and the action of the immune system confer robust airway surveillance and protection against environmental irritants and pathogens. However, aberrant activation of the immune system or sensitization of the nervous system can contribute to the development of autoimmune airway disorders. Transient receptor potential ion channels and voltage-gated Na+ channels play critical roles in sensing noxious stimuli within the respiratory tract and interacting with the immune system to generate neurogenic inflammation and airway hypersensitivity. Although recent studies have revealed the involvement of nociceptor neurons in airway diseases, the further neural circuitry underlying airway protection remains elusive. Unraveling the mechanism underpinning neural circuit regulation in the airway may provide precise therapeutic strategies and valuable insights into the management of airway diseases.

BALB/c and C57BL/6 mice differ in oxidant and antioxidant responses in innate and adaptive immune cells in an asthma model induced by cockroach allergens

Asthma is a complex and heterogenous disease affected by a multitude of factors. Several phenotypes of asthma exist which are influenced by various molecular mechanisms that include presence of antioxidant and oxidant enzymes in different immune cells such as dendritic cells (DCs), alveolar macrophages (AMs), neutrophils, and T cells. Close interaction between epithelial cells and dendritic cells initiates complex pathogenesis of asthma followed by involvement of other innate and adaptive immune cells. In chronic phase of the disease, these immune cells support each other in amplification of airway inflammation where oxidant-antioxidant balance is known to be an important contributing factor. Genetic variability in antioxidant response may influence the development of airway inflammation, however it has not been studied in mice yet. The two most studied mice strains, i.e. BALB/c and C57BL/6 are reported to have dissimilar airway responses to the same allergens due to their genetic makeup. In this investigation, we explored whether these strains had any differences in pulmonary oxidant-antioxidant system (Nrf2, SOD2, iNOS, HO-1, nitrotyrosine) in different immune cells (DCs, AMs, neutrophils, T cells), airway inflammation (presence of eosinophils and/or neutrophils) and mucus production in response to repeated cockroach allergen extract (CE) mouse model of asthma. Our data show that C57BL/6 mice had better induction of antioxidant system than BALB/c mice. Consequently, iNOS/nitrotyrosine levels were much exaggerated in BALB/c than C57BL/6 mice. As a result, BALB/c mice developed mixed granulocytic airway inflammation, whereas C57BL/6 developed mostly eosinophilic airway inflammation. Our data suggest that an exaggerated oxidant generation along with a weak antioxidant induction in response to a natural allergen on a susceptible genetic background may determine development of severe asthma phenotype such as mixed granulocyte inflammation.

B-cell-derived IL-10 promotes allergic sensitization in asthma regulated by Bcl-3

Aeroallergen sensitization, mainly mediated by lung epithelium and dendritic cells (DCs), is integral to allergic asthma pathogenesis and progression. IL-10 has a dual role in immune responses, as it inhibits myeloid cell activation but promotes B-cell responses and epithelial cell proliferation. Here, we report a proinflammatory function of B-cell-derived IL-10 modulated by Bcl-3 in allergic asthma. Specifically, Bcl-3-/- mice showed elevated IL-10 levels and were found to be highly vulnerable to allergic asthma induced by house dust mites (HDMs). IL-10 had a positive correlation with the levels of the DC chemoattractant CCL-20 in HDM-sensitized mice and in patients with asthma and induced a selective increase in CCL-20 production by mouse lung epithelial cells. Blockade of IL-10 or IL-10 receptors during sensitization dampened both HDM-induced sensitization and asthma development. IL-10 levels peaked 4 h post sensitization with HDM and IL-10 was primarily produced by B cells under Bcl-3-Blimp-1-Bcl-6 regulation. Mice lacking B-cell-derived IL-10 displayed decreased lung epithelial CCL-20 production and diminished DC recruitment to the lungs upon HDM sensitization, thereby demonstrating resistance to HDM-induced asthma. Moreover, responses to HDM stimulation in Bcl-3-/- mice lacking B-cell-derived IL-10 were comparable to those in Bcl-3+/+ mice. The results revealed an unexpected role of B-cell-derived IL-10 in promoting allergic sensitization and demonstrated that Bcl-3 prevents HDM-induced asthma by inhibiting B-cell-derived IL-10 production. Thus, targeting the Bcl-3/IL-10 axis to inhibit allergic sensitization is a promising approach for treating allergic asthma. IL-10 is released rapidly from lung plasma cells under Bcl-3-Blimp-1-Bcl-6 regulation upon house dust mite exposure and amplifies lung epithelial cell (EC)-derived CCL-20 production and subsequent dendritic cell (DC) recruitment to promote allergic sensitization in asthma.

Lignosus rhinocerotis extract ameliorates airway inflammation and remodelling via attenuation of TGF-β1 and Activin A in a prolonged induced allergic asthma model

Allergic asthma is associated with chronic airway inflammation and progressive airway remodelling. The sclerotium of Lignosus rhinocerotis (Cooke) Ryvarden (Tiger Milk mushroom) is used traditionally to treat various illnesses, including asthma in Southeast Asia. This study was carried out to evaluate the effect of L. rhinocerotis extract (LRE) on airway inflammation and remodelling in a chronic model of asthma. The present study investigated the therapeutic effects of LRE on airway inflammation and remodelling in prolonged allergen challenged model in allergic asthma. Female Balb/C mice were sensitised using ovalbumin (OVA) on day 0 and 7, followed by OVA-challenged (3 times/week) for 2, 6 and 10 weeks. LRE (125, 250, 500 mg/kg) were administered by oral gavage one hour after every challenge. One group of mice were left untreated after the final challenge for two weeks. LRE suppressed inflammatory cells and Th2 cytokines (IL-4, IL-5 and IL-13) in BALF and reduced IgE level in the serum. LRE also attenuated eosinophils infiltration and goblet cell hyperplasia in the lung tissues; as well as ameliorated airway remodelling by reducing smooth muscle thickness and reducing the expressions of TGF-β1 and Activin A positive cell in the lung tissues. LRE attenuated airway inflammation and remodelling in the prolonged allergen challenge of allergic asthma model. These findings suggest the therapeutic potential of LRE as an alternative for the management of allergic asthma.

Targeting calcium signaling by inositol trisphosphate receptors: A novel mechanism for the anti-asthmatic effects of Houttuynia cordata

Asthma is a chronic inflammatory disease characterized by airway hypersensitivity and remodeling. The current treatments provide only short-term benefits and may have undesirable side effects; thus, alternative or supplementary therapy is needed. Because intracellular calcium (Ca²⁺) signaling plays an essential role in regulating the contractility and remodeling of airway smooth muscle cells, the targeting of Ca²⁺ signaling is a potential therapeutic strategy for asthma. Houttuynia cordata is a traditional Chinese herb that is used to treat asthma due to its anti-allergic and anti-inflammatory properties. We hypothesized that H. cordata might modulate intracellular Ca²⁺ signaling and could help relieve asthmatic airway remodeling. We found that the mRNA and protein levels of inositol trisphosphate receptors (IP₃Rs) were elevated in interleukin-stimulated primary human bronchial smooth muscle cells and a house dust mite-sensitized model of asthma. The upregulation of IP₃R expression enhanced intracellular Ca²⁺ release upon stimulation and contributed to airway remodeling in asthma. Intriguingly, pretreatment with H. cordata essential oil rectified the disruption of Ca²⁺ signaling, mitigated asthma development, and prevented airway narrowing. Furthermore, our analysis suggested that houttuynin/2-undecanone could be the bioactive component in H. cordata essential oil because we found similar IP₃R suppression in response to the commercially available derivative sodium houttuyfonate. An in silico analysis showed that houttuynin, which downregulates IP₃R expression, binds to the IP₃ binding domain of IP₃R and may mediate a direct inhibitory effect. In summary, our findings suggest that H. cordata is a potential alternative treatment choice that may reduce asthma severity by targeting the dysregulation of Ca²⁺ signaling.

RNA viruses alter house dust mite physiology and allergen production with no detected consequences for allergenicity

RNA viruses have recently been detected in association with house dust mites, including laboratory cultures, dust samples, and mite-derived pharmaceuticals used for allergy diagnosis. This study aimed to assess the incidence of viral infection on Dermatophagoides pteronyssinus physiology and on the allergenic performance of extracts derived from its culture. Transcriptional changes between genetically identical control and virus-infected mite colonies were analysed by RNAseq with the support of a new D. pteronyssinus high-quality annotated genome (56.8 Mb, 108 scaffolds, N50 = 2.73 Mb, 96.7% BUSCO-completeness). Extracts of cultures and bodies from both colonies were compared by inspecting major allergen accumulation by enzyme-linked immunosorbent assay (ELISA), allergen-related enzymatic activities by specific assays, airway inflammation in a mouse model of allergic asthma, and binding to allergic patient's sera IgE by ImmunoCAP. Viral infection induced a significant transcriptional response, including several immunity and stress-response genes, and affected the expression of seven allergens, putative isoallergens and allergen orthologs. Major allergens were unaffected except for Der p 23 that was upregulated, increasing ELISA titers up to 29% in infected-mite extracts. By contrast, serine protease allergens Der p 3, 6 and 9 were downregulated, being trypsin and chymotrypsin enzymatic activities reduced up to 21% in extracts. None of the parameters analysed in our mouse model, nor binding to human IgE were significantly different when comparing control and infected-mite extracts. Despite the described physiological impact of viral infection on the mites, no significant consequences for the allergenicity of derived extracts or their practical use in allergy diagnosis have been detected.

A retro-inverso modified peptide alleviated ovalbumin-induced asthma model by affecting glycerophospholipid and purine metabolism of immune cells

Allergic asthma is a heterogeneous disease involving a variety of inflammatory cells. Immune imbalance or changes in the immune microenvironment are the essential causes that promote inflammation in allergic asthma. Tetraspanin CD81 can be used as a platform for receptor clustering and signal transmission owing to its special transmembrane structure and is known to participate in the physiological processes of cell proliferation, differentiation, adhesion, and migration. Previous studies have shown that CD81-targeting peptidomimetics exhibit anti-allergic lung inflammation. However, due to the low metabolic stability of peptide drugs, their druggability is limited. Here, we aimed to generate a metabolically stable anti-CD81 peptide, evaluate its anti-inflammatory action and establish its mechanism of action. Based on previous reports, we applied retro-inverse peptide modification to obtain a new compound, PD00 (NH2-D-Gly-D-Ser-D-Thr-D-Tyr-D-Thr-D-Gln-D-Gly-COOH), with high metabolic stability. Enhanced ultraperformance liquid chromatography-tandem mass spectrometry was used to investigate the in vitro and in vivo metabolic stabilities of PD00. The affinities of PD00 and CD81 were studied using molecular docking and surface plasmon resonance techniques. An ovalbumin (OVA)-induced asthma model was used to evaluate the effects of PD00 in vivo. Mice were treated with different concentrations of PD00 (175 and 350 μg/kg) for 10 days. Airway hyperresponsiveness (AHR) to acetyl-β-methacholine (Mch), inflammatory cell counts in the bronchoalveolar lavage fluid, and serum OVA-specific IgE levels were detected in the mice at the end of the experiment. Lung tissues were collected for haematoxylin and eosin staining, untargeted metabolomic analysis, and single-cell transcriptome sequencing. PD00 has a high affinity for CD81; therefore, administration of PD00 markedly ameliorated AHR and airway inflammation in mice after OVA sensitisation and exposure. Serum OVA-specific IgE levels decreased considerably. In addition, PD00 treatment increased glycerophospholipid and purine metabolism in immune cells. Collectively, PD00 may regulate the glycerophospholipid and purine metabolism pathways to ameliorate the pathophysiological features of asthma. These findings suggest that PD00 is a potential compound for the treatment of asthma.

2-Undecanone alleviates asthma by inhibiting NF-κB pathway

Asthma is characterized by airway inflammation and remodeling. 2-Undecanone (methyl nonyl ketone), a volatile organic compound originating from Houttuynia cordata, has the potential to ameliorate inflammatory diseases. This study aimed to explore potential benefits of 2-undecanone in asthma. 2-Undecanone (100, 200, or 400 mg/kg) was administered intragastrically to ovalbumin (OVA)-challenged BALB/c mice. Lung tissues were collected to observe histopathological changes, and bronchoalveolar lavage fluid (BALF) was collected for the detection of inflammatory cells and cytokine production. The results showed that 2-undecanone ameliorated OVA-induced pathologic changes of lungs, including reducing inflammatory cell infiltration, goblet cell hyperplasia, and airway smooth muscle thickness. The number of inflammatory cells and the levels of IL-4, IL-5, IL-13, and IgE in BALF were decreased by 2-undecanone in asthmatic mice. Furthermore, abnormal activation of NF-κB pathway in lung tissues of asthmatic mice was impeded by 2-undecanone. In vitro, 2-undecanone (12.5, 25, or 50 µM) suppressed platelet-derived growth factor-BB-induced proliferation and migration of primary airway smooth muscle cells (ASMCs), and inhibited the switching of ASMCs from contractile phenotype to synthetic phenotype. Consistently, 2-undecanone blocked NF-κB activation in ASMCs. Collectively, 2-undecanone relieves asthma through alleviating airway inflammation and remodeling, and this beneficial effect is achieved by inhibiting NF-κB pathway.

Maternal Lactobacillus rhamnosus administration impacts neonatal CD4 T-cell activation and prevents murine T helper 2-type allergic airways disease

Gut microbiota plays a role in the neonatal immune education and could influence susceptibility to Th2-type immune disorders, such as allergies, the most prevalent chronic diseases in early childhood. We studied the impact of oral Lactobacillus rhamnosus (L.rhamnosus) supplementation to pregnant/breastfeeding C57BL/6 mice on the development of allergic airways disease in their offspring. We observed that mice, from L.rhamnosus-treated mothers, inoculated with ovalbumin (OVA)-Aluminium hydroxide (ALUM) at 3 days of life and challenged intranasally 4 weeks later showed decreased Th2-associated cytokines, IgE and IgG1, lung eosinophilia and airway hyper-reactivity compared to OVA-sensitized mice from untreated mothers. In that setting, the L.rhamnosus treatment increased the number and maturation of splenic neonatal type 1 conventional dendritic cells (cDC1) that remained largely dominant over the cDC2 and favored their OVA-specific Th1 differentiation. In response to inhaled house dust mite (HDM) allergen, the maternal L.rhamnosus supplementation increased the number of neonatal pulmonary cDC1 expressing lower amount of costimulatory molecules compared with no supplementation and decreased the number of cDC2 without affecting their costimulatory molecules expression. An HDM-specific Foxp3⁺RORγt⁺ Treg polarization was monitored in the lung draining lymph nodes. Finally, we confirmed the inhibitory effect of maternal L.rhamnosus treatment on all the measured features of the HDM allergic airways reaction in their offspring. We conclude that maternal L.rhamnosus administration prevents Th2-type allergic airways disease in their neonates by favoring splenic cDC1/Th1 responses against ALUM-adjuvanted OVA or by promoting a pulmonary Foxp3⁺RORγt⁺ Treg activation against inhaled HDM.

Therapeutic Potential of Controlled Delivery Systems in Asthma: Preclinical Development of Flavonoid-Based Treatments

Asthma is a chronic disease with increasing prevalence and incidence, manifested by allergic inflammatory reactions, and is life-threatening for patients with severe disease. Repetitive challenges with the allergens and limitation of treatment efficacy greatly dampens successful management of asthma. The adverse events related to several drugs currently used, such as corticosteroids and β-agonists, and the low rigorous adherence to preconized protocols likely compromises a more assertive therapy. Flavonoids represent a class of natural compounds with extraordinary antioxidant and anti-inflammatory properties, with their potential benefits already demonstrated for several diseases, including asthma. Advanced technology has been used in the pharmaceutical field to improve the efficacy and safety of drugs. Notably, there is also an increasing interest for the application of these techniques using natural products as active molecules. Flavones, flavonols, flavanones, and chalcones are examples of flavonoid compounds that were tested in controlled delivery systems for asthma treatment, and which achieved better treatment results in comparison to their free forms. This review aims to provide a comprehensive understanding of the development of novel controlled delivery systems to enhance the therapeutic potential of flavonoids as active molecules for asthma treatment.

Ferret acute lung injury model induced by repeated nebulized lipopolysaccharide administration

Inflammatory lung diseases affect millions of people worldwide. These diseases are caused by a number of factors such as pneumonia, sepsis, trauma, and inhalation of toxins. Pulmonary function testing (PFT) is a valuable functional methodology for better understanding mechanisms of lung disease, measuring disease progression, clinical diagnosis, and evaluating therapeutic interventions. Animal models of inflammatory lung diseases are needed that accurately recapitulate disease manifestations observed in human patients and provide an accurate prediction of clinical outcomes using clinically relevant pulmonary disease parameters. In this study, we evaluated a ferret lung inflammation model that closely represents multiple clinical manifestations of acute lung inflammation and injury observed in human patients. Lipopolysaccharide (LPS) from Pseudomonas aeruginosa was nebulized into ferrets for 7 repeated daily doses. Repeated exposure to nebulized LPS resulted in a restrictive pulmonary injury characterized using Buxco forced maneuver PFT system custom developed for ferrets. This is the first study to report repeated forced maneuver PFT in ferrets, establishing lung function measurements pre- and post-injury in live animals. Bronchoalveolar lavage and histological analysis confirmed that LPS exposure elicited pulmonary neutrophilic inflammation and structural damage to the alveoli. We believe this ferret model of lung inflammation, with clinically relevant disease manifestations and parameters for functional evaluation, is a useful pre-clinical model for understanding human inflammatory lung disease and for the evaluation of potential therapies.

HDM induces distinct immunometabolic phenotype in macrophages in TLR4-dependent manner

Asthma is one of the most common chronic diseases. In many cases it is preceded by the development of an immune response to allergens such as animal fur, dust, pollens and etc. In human population this disease is heterogeneous, and no selective drugs are available at the moment for some endotypes of asthma. The role of the adaptive immune system in the pathogenesis of asthma was extensively studied, while the role of innate immune cells, in particular myeloid cells, was not sufficiently addressed. Myeloid cells, such as macrophages and dendritic cells, are characterized by high plasticity, heterogenicity and ability to undergo polarization in response to various pathogenic stimuli, including those engaging innate immune receptors. Recently, special attention was drawn to the link between polarization of macrophages and cell metabolism. We hypothesized that immunometabolic reprogramming of myeloid cells, in particular, of macrophages and dendritic cells during sensitization with an allergen may affect further immune response and asthma development. To test this hypothesis, we generated distinct types of myeloid cells in vitro from murine bone marrow and analyzed their immunometabolic profiles upon activation with house dust mite extract (HDM) and its key active components. We found that the combination of lipopolysaccharide (LPS) and beta-glucan is sufficient to upregulate proinflammatory cytokine production as well as respiratory and glycolytic capacity of myeloid cells, comparably to HDM. This specific immunometabolic phenotype was associated with altered mitochondrial morphology and possibly with increased ROS production in macrophages. Moreover, we found that both TNF production and metabolic remodeling of macrophages in response to HDM are TLR4-dependent processes. Altogether, these results expand our understanding of molecular mechanisms underlying asthma induction and pathogenesis and may potentially lead to new therapeutic strategies for the treatment of this disease.

Sesquiterpene lactones from Xanthium sibiricum Patrin alleviate asthma by modulating the Th1/Th2 balance in a murine model

BACKGROUND

Asthma is a complex airway disease involving a variety of cells and cytokines. Xanthium sibiricum Patrin ex Widder (X. sibiricum) is a traditional Chinese medicine for various immune diseases, especially allergic rhinitis and asthma. Sesquiterpene lactones are the main bioactive and most abundant constituent, and are characteristic component of the plant. We explore whether sesquiterpene lactones from X. sibiricum (SL-XS) is the main active constitute for its anti-asthma activity.

PURPOSE

In the present study, SL-XS was isolated, the major compounds were isolated and identified in extract of SL-XS, and the anti-asthma activity of SL-XS was validated in vivo.

METHODS

SL-XS was isolated by a standard phytochemical method. The structures of major sesquiterpene lactones were identified by NMR and LC-MS spectra. The contents of major SL-XS were analyzed by HPLC. The anti-asthma effect of SL-XS was evaluated in a house dust mite (HDM)-induced mouse model.

RESULTS

The sesquiterpene lactones were isolated from X. sibiricum, and five major constituents i.e., 8‑epi-xanthatin-1β, 5β-epoxide (1), tomentosin (2), 8‑epi-xanthatin (3), 2‑epi-xanthumin (4) and sibiriolide B (5) were identified from SL-XS. Oral administration of SL-XS dose-dependently ameliorated airway inflammation and remodeling in HDM-challenged asthma mouse model. Furthermore, SL-XS treatment inhibited the upregulation of proinflammatory and Th2 cytokines, while reversed the downregulation of Th1 related cytokines. In addition, SL-XS regulated the balance between T-bet and GATA-3. Moreover, SL-XS inhibited the upregulation of JAK1, p-JAK1, JAK2, p-JAK2, JAK3, p-JAK3 and p-STAT6 in HDM-challenged mice.

CONCLUSION

The sesquiterpene lactones including five major constituents may be the main anti-asthma active constituent of X. sibiricum. SL-XS exerted its anti-asthma effect by modulating the Th1/Th2 balance via the JAK/STAT signaling pathway.

Dual Effect of Low-Molecular-Weight Bioregulators of Bacterial Origin in Experimental Model of Asthma

Asthma is one of the most common noncommunicable diseases, affecting over 200 million people. A large number of drugs control asthma attacks, but there is no effective therapy. Identification of reasons for asthma and preventing this disease is a relevant task. The influence of bacterial components is necessary for the normal development of the immune system and the formation of an adequate immune response to antigens. In the absence of microorganisms or their insufficient exposure, the prerequisites are formed for excessive reactivity to harmless antigens. In the present study, we analyzed cellular and humoral factors in a standard mouse model of OVA-induced asthma modified by 5-fold intraperitoneal injection of bacterial cell wall fragments of glucosaminylmuramyl dipeptide (GMDP) 5 μg/animal or 1 μg lipopolysaccharide (LPS) per animal for 5 days before sensitization by ovalbumin (OVA). Preliminary administration of LPS or GMDP to animals significantly reduced goblet cells as well as the number of neutrophils, lymphocytes, and eosinophils in bronchoalveolar lavage, wherein GMDP corrected neutrophilia to a 2-fold degree, and LPS reduced the severity of eosinophilia by 1.9 times. With OVA administration of GMDP or LPS at the sensitization stage, an increase in the total number of bronchoalveolar lavage cells due to neutrophils, macrophages, lymphocytes, and eosinophils in relation to the group with asthma without GMDP or LPS was observed. The administration of GMDP or LPS to normal mice without asthma for 5 days had no statistically significant effect on the change in the number and population composition of cells in bronchoalveolar lavage in comparison with the control group receiving PBS. As a result of a study in a mouse model of asthma, a dual effect of LPS and GMDP was established: the introduction of LPS or GMDP before sensitization reduces neutrophilia and eosinophilia, while the introduction of LPS or GMDP together with an allergen significantly increases neutrophilia and eosinophilia. The study of the immunoglobulin status shows that in normal-asthma mice, GMDP and LPS slightly increase IgA in bronchoalveolar lavage; at the same time, in the asthma model, injections of GMDP or LPS before sensitization contribute to a significant decrease in IgA (2.6 times and 2.1 times, respectively) in BALF and IgE (2.2 times and 2.0 times, respectively) in blood serum. In an experimental model of asthma, the effect of GMDP and LPS was multidirectional: when they are repeatedly administered before sensitization, the bacterial components significantly reduce the severity of the allergic process, while in the case of a joint injection with an allergen, they increase the influx of macrophages, lymphocytes, and neutrophils into the lungs, which can aggravate the course of pathological process. Thus, the insufficient effect of antigens of a bacterial nature, in particular, with prolonged use of antibiotics can be compensated for by substances based on low-molecular-weight bioregulators of bacterial origin to establish the missing signals for innate immunity receptors, whose constant activation at a certain level is necessary to maintain homeostasis.

Ginger-derived compounds exert in vivo and in vitro anti-asthmatic effects by inhibiting the T-helper 2 cell-mediated allergic response

6-Shogaol (SHO) and 6-gingerol (GIN), naturally derived compounds of ginger (Zingiber officinale Roscoe), have been found to have anti-allergic effects on dermatitis-like skin lesions and rhinitis. Although SHO and GIN have demonstrated a potential in various inflammatory diseases, their efficacy and mechanism in asthma have not been largely examined. Therefore, the present study demonstrated the anti-asthmatic effects of SHO and GIN on the T-helper (Th) 2 cell-mediated allergic response pathway in an ovalbumin (OVA)-induced asthma mouse model. The asthma mouse model was established with an intraperitoneal (i.p.) injection of 50 µg OVA and 1 mg aluminum hydroxide with or without an i.p. injection of SHO and GIN (10 mg/kg) before treatment with OVA. In addition, the current study assessed mast cell degranulation in antigen-stimulated RBL-2H3 cells under different treatment conditions (SHO or GIN at 0, 10, 25, 50 and 100 nM) and determined the mRNA and protein levels of anti-oxidative enzymes [superoxide dismutase (SOD)1, SOD2, glutathione peroxidase-1/2, catalase] in lung tissues. SHO and GIN inhibited eosinophilia in the bronchoalveolar lavage fluids and H&E-stained lung tissues. Both factors also decreased mucus production in periodic acid-Schiff-stained lung tissues and the levels of Th2 cytokines in these tissues. GIN attenuated oxidative stress by upregulating the expression levels of anti-oxidative proteins. In an in vitro experiment, the degranulation of RBL-2H3 rat mast cells was significantly decreased. It was found that SHO and GIN effectively suppressed the allergic response in the mouse model by inhibiting eosinophilia and Th2 cytokine production. Collectively, it was suggested that SHO can inhibit lung inflammation by attenuating the Th2 cell-mediated allergic response signals, and that GIN can inhibit lung inflammation and epithelial cell remodeling by repressing oxidative stress. Therefore, SHO and GIN could be used therapeutically for allergic and eosinophilic asthma.

Specific Immunotherapy in a Murine Model of Grass Pollen (Phl p5b)-Induced Airway Inflammation

Background: The use of ovalbumin as a model allergen in murine models of allergic asthma is controversially discussed since it is not an aeroallergen and sensitization can only be achieved by using strong Th2-inducing adjuvants. Therefore, in this study, a murine model of asthma has been established in which sensitization against the major grass pollen allergen Phl p5b was performed without using aluminum hydroxide (alum). We used this model for specific immunotherapy.

Methods: Female, 5–6-week-old mice were sensitized by six subcutaneous (s.c.) injections of 20 μg Phl p5b followed by four provocations to induce allergic airway inflammation. For desensitization, 1 mg of Phl p5b was injected subcutaneously during allergen challenge for one to a maximum of four times. Three days after the last challenge, the allergic immune response was analyzed.

Results: Sensitized and challenged animals showed a significant infiltration of eosinophils into the airways, and the production of interleukin-5 (IL-5) by in vitro re-stimulated splenocytes could be detected. Furthermore, hyper-responsiveness of the airways was verified by invasive measurement of airway resistance in methacholine-challenged animals. Desensitized animals showed a significant reduction of all parameters.

Conclusion: In this study, a murine model of asthma has successfully been established by sensitization against the clinically relevant allergen Phl p5b without using alum. S.c. injection of allergen dose dependently led to desensitization of sensitized mice. We suggest that this model is useful to study adjuvant effects of immune modulatory substances on immunotherapy without the interference of alum.

Pulmonary Eosinophils at the Center of the Allergic Space-Time Continuum

Eosinophils are typically a minority population of circulating granulocytes being released from the bone-marrow as terminally differentiated cells. Besides their function in the defense against parasites and in promoting allergic airway inflammation, regulatory functions have now been attributed to eosinophils in various organs. Although eosinophils are involved in the inflammatory response to allergens, it remains unclear whether they are drivers of the asthma pathology or merely recruited effector cells. Recent findings highlight the homeostatic and pro-resolving capacity of eosinophils and raise the question at what point in time their function is regulated. Similarly, eosinophils from different physical locations display phenotypic and functional diversity. However, it remains unclear whether eosinophil plasticity remains as they develop and travel from the bone marrow to the tissue, in homeostasis or during inflammation. In the tissue, eosinophils of different ages and origin along the inflammatory trajectory may exhibit functional diversity as circumstances change. Herein, we outline the inflammatory time line of allergic airway inflammation from acute, late, adaptive to chronic processes. We summarize the function of the eosinophils in regards to their resident localization and time of recruitment to the lung, in all stages of the inflammatory response. In all, we argue that immunological differences in eosinophils are a function of time and space as the allergic inflammatory response is initiated and resolved.

Purified Native and Recombinant Major Alternaria alternata Allergen (Alt a 1) Induces Allergic Asthma in the Murine Model

Aeroallergens such us the spores of Alternaria alternata are described as the most important agents associated with respiratory allergies and severe asthma. Various experimental models of asthma have been developed using A. alternata extracts to study the pathogenesis of asthma, establishing the main parameters that trigger the asthmatic response. In this study, we describe a mouse model of asthma induced only by Alt a 1. To induce the allergic response, mice were challenged intranasally with the major allergen of A. alternata, Alt a 1. The presence of eosinophils in the lungs, elevated concentrations of Th2 family cytokines, lymphocyte proliferation and elevated IgE total serum levels indicated that the sensitisation and challenge with Alt a 1 induced the development of airway inflammation. Histological studies showed an eosinophilic cellular infiltrate in the lung tissue of mice instilled with Alt a 1. We demonstrate that Alt a 1 alone is capable of inducing a lung inflammatory response with an increase in IgE serum levels mimicking the allergic asthma immunoresponse when it is administered into BALB/c mice. This model will allow the evaluation of the immunoregulatory or immunotolerant capacity of several molecules that can be used in targeted immunotherapy for fungal allergic asthma.

Synthesis and Biochemical Evaluation of Baicalein Prodrugs

Baicalein (5,6,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one), a flavonoid analog from Scutellaria baicalensis, possesses several pharmacological activities including antioxidant, antiproliferative, and anti-inflammatory activities. We previously reported that baicalein inhibits the thymic stromal lymphopoietin (TSLP)/TSLP receptor (TSLPR) signaling pathways and can be used as an active ingredient in the treatment of asthma and atopic dermatitis. However, baicalein is rapidly metabolized to baicalin and baicalein-6-O-glucuronide in vivo, which limits its preclinical and clinical use. In this study, we designed, synthesized, and evaluated baicalein prodrugs that protect the OH group at the 7-position of the A ring in baicalein with the amino acid carbamate functional group. Comprehensive in vitro and in vivo studies identified compound 2 as a baicalein prodrug candidate that improved the plasma exposure of baicalein in mouse animal studies. Our results demonstrated that this prodrug approach could be further adopted to discover oral baicalein prodrugs.

Myeloid differentiation protein-2 has a protective role in house dust mite-mediated asthmatic characteristics with the proinflammatory regulation of airway epithelial cells and dendritic cells

BACKGROUND

Myeloid differentiation protein-2 (MD-2) is a lipopolysaccharide-binding protein involved in lipopolysaccharide signalling via Toll-like receptor 4 (TLR4). TLR4 plays an essential role in HDM-mediated allergic airway inflammation. Moreover, MD-2 is structurally similar to Der f 2, a major allergen from house dust mite (HDM).

OBJECTIVES

We aimed to clarify the role of MD-2 in the pathogenesis of HDM-mediated allergic airway inflammation.

METHODS

Wild-type (WT), TLR4 knockout and MD-2 knockout mice were subjected to intranasal instillation of HDM extract, and asthmatic features were evaluated. We also evaluated gene sets regulated by MD-2 in HDM-treated airway epithelial cells and examined the function of dendritic cells from lymph nodes and from lungs.

RESULTS

Aggravated allergic airway inflammation with increased airway hyperresponsiveness was observed in MD-2 knockout mice compared with WT and TLR4 knockout mice. Global gene expression analysis revealed an MD-2 regulated proinflammatory response and reconstituted TLR4 signalling in airway epithelial cells. The ability of dendritic cells to evoke an allergic immune response was enhanced in MD-2 knockout mice.

CONCLUSIONS & CLINICAL RELEVANCE

MD-2 plays a protective role in HDM-induced airway allergy with the proinflammatory regulation of airway epithelial cells and dendritic cells. MD-2 may serve as a therapeutic target in the treatment of asthma.

Mouse Models of Asthma: Characteristics, Limitations and Future Perspectives on Clinical Translation

Asthma is a complex and heterogeneous inflammatory airway disease primarily characterized by airway obstruction, which affects up to 15% of the population in Westernized countries with an increasing prevalence. Descriptive laboratory and clinical studies reveal that allergic asthma is due to an immunological inflammatory response and is significantly influenced by an individual's genetic background and environmental factors. Due to the limitations associated with human experiments and tissue isolation, direct mouse models of asthma provide important insights into the disease pathogenesis and in the discovery of novel therapeutics. A wide range of asthma models are currently available, and the correct model system for a given experimental question needs to be carefully chosen. Despite recent advances in the complexity of murine asthma models, for example humanized murine models and the use of clinically relevant allergens, the limitations of the murine system should always be acknowledged, and it remains to be seen if any single murine model can accurately replicate all the clinical features associated with human asthmatic disease.

In vivo reprogramming of pathogenic lung TNFR2+ cDC2s by IFNβ inhibits HDM-induced asthma

Asthma is a common inflammatory lung disease with no known cure. Previously, we uncovered a lung TNFR2⁺ conventional DC2 subset (cDC2s) that induces regulatory T cells (T_regs) maintaining lung tolerance at steady state but promotes T_H2 response during house dust mite (HDM)-induced asthma. Lung IFNβ is essential for TNFR2⁺ cDC2s-mediated lung tolerance. Here, we showed that exogenous IFNβ reprogrammed T_H2-promoting pathogenic TNFR2⁺ cDC2s back to tolerogenic DCs, alleviating eosinophilic asthma and preventing asthma exacerbation. Mechanistically, inhaled IFNβ, not IFNα, activated ERK2 signaling in pathogenic lung TNFR2⁺ cDC2s, leading to enhanced fatty acid oxidation (FAO) and lung T_reg induction. Last, human IFNβ reprogrammed pathogenic human lung TNFR2⁺ cDC2s from patients with emphysema ex vivo. Thus, we identified an IFNβ-specific ERK2-FAO pathway that might be harnessed for DC therapy.

SERPINB10 contributes to asthma by inhibiting the apoptosis of allergenic Th2 cells

BACKGROUND

Serine peptidase inhibitor, clade B, member 10 (SERPINB10) contributes to allergic inflammation in asthma. However, its role in the T-helper type 2 (Th2) response of allergic asthma is not known. The goal of this study was to unveil the function of SERPINB10 in the Th2 response of allergic asthma and the mechanism by which SERPINB10 affects the viability of Th2 cells.

METHODS

Th2 cytokines and serum levels of house dust mite (HDM)-specific IgE in bronchoalveolar lavage fluid were examined by ELISA in an HDM-induced asthma model. The number and apoptosis of Th1 and Th2 cells in mouse lungs were measured by flow cytometry. Naïve CD4 T cells from patients with asthma were cultured under appropriate polarizing conditions to generate Th1 and Th2 cells. SERPINB10 expression in polarized Th1 and Th2 cells was quantified by real-time reverse transcription-quantitative polymerase chain reaction. SERPINB10 expression was knocked down in human CD4 T cells with lentivirus.

RESULTS

Knockdown of SERPINB10 expression significantly diminished HDM-induced Th2 cytokine secretion and level of HDM-specific IgE. After HDM exposure, SERPINB10-knockdown mice had diminished numbers of Th2 cells, but similar numbers of Th1 cells, compared with those in negative-control mice. Th2 cells of SERPINB10-knockdown mice were more susceptible to apoptosis than that of control mice. Stimulating T-cell receptors (TCRs) with anti-CD3 antibody caused upregulation of SERPINB10 expression in polarized Th2 cells, but not polarized Th1 cells. Knockdown of SERPINB10 expression resulted in fewer numbers and greater apoptosis of polarized Th2 cells.

CONCLUSION

Our results suggest that SERPINB10 may contribute to allergic inflammation and the Th2 response of asthma by inhibiting the apoptosis of Th2 cells.

Na+/H+ Exchanger Regulatory Factor 1 Mediates the Pathogenesis of Airway Inflammation in a Murine Model of House Dust Mite-Induced Asthma

Na+/H+ exchanger regulatory factor 1 (NHERF1), a class I PDZ-binding protein, regulates G protein-coupled receptor signaling in some cell types. NHERF1 also functions as a scaffolding protein and activates non-G protein-coupled receptor signaling pathways, thereby contributing to the pathogenesis of various diseases. Although we have previously shown that NHERF1 regulates mast cell functions, there is little information regarding the role of NHERF1 in other immune cells. How NHERF1 regulates the pathogenesis of allergic disease such as asthma also remains unknown. In the current study, we show that NHERF1 promotes allergic airway inflammation in a house dust mite extract (HDME)-induced mouse model of asthma. Specifically, HDME-specific serum IgE levels, airway leukocyte numbers, and goblet cell hyperplasia were reduced in NHERF1+/- mice as compared with NHERF1+/+ mice. Interestingly, the gene expression of inflammatory (IL-17a, IL-25, and IL-33) as well as T helper 2 (Th2) cytokines (IL-4, IL-5, and IL-13) and several chemokines that recruit eosinophils, neutrophils, and lymphocytes were also decreased in the lungs of NHERF1+/- mice exposed to HDME. Consistent with these observations, microRNAs regulating mucus production, inflammation, Th2 effector functions, and IL-13 expression were increased in the lungs of HDME-treated NHERF1+/- mice. Overall, our studies reveal a unique role for NHERF1 in regulating asthma pathogenesis, and further elucidation of the mechanisms through which NHERF1 modulates allergic inflammation will lead to the development of new therapeutic strategies for asthma.

IL-6 family cytokines in respiratory health and disease

Chronic lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and lung fibrosis represent a major burden on healthcare systems with limited effective therapeutic options. Developing effective treatments for these debilitating diseases requires an understanding of how alterations at the molecular level affect lung macroscopic architecture. A common theme among these lung disorders is the presence of an underlying dysregulated immune system which can lead to sustained chronic inflammation. In this respect, several inflammatory cytokines have been implicated in the pathogenesis of lung diseases, thus leading to the notion that cytokines are attractive therapeutic targets for these disorders. In this review, we discuss and highlight the recent breakthroughs that have enhanced our understanding of the role of the interleukin (IL)-6 family of cytokines in lung homeostasis and chronic diseases including asthma, COPD, lung fibrosis and lung cancer.

The Hygiene Hypothesis and New Perspectives-Current Challenges Meeting an Old Postulate

During its 30 years history, the Hygiene Hypothesis has shown itself to be adaptable whenever it has been challenged by new scientific developments and this is a still a continuously ongoing process. In this regard, the mini review aims to discuss some selected new developments in relation to their impact on further fine-tuning and expansion of the Hygiene Hypothesis. This will include the role of recently discovered classes of innate and adaptive immune cells that challenges the old Th1/Th2 paradigm, the applicability of the Hygiene Hypothesis to newly identified allergy/asthma phenotypes with diverse underlying pathomechanistic endotypes, and the increasing knowledge derived from epigenetic studies that leads to better understanding of mechanisms involved in the translation of environmental impacts on biological systems. Further, we discuss in brief the expansion of the Hygiene Hypothesis to other disease areas like psychiatric disorders and cancer and conclude that the continuously developing Hygiene Hypothesis may provide a more generalized explanation for health burden in highly industrialized countries also relation to global changes.

Deletion of IL-4Rα signaling on B cells limits hyperresponsiveness depending on antigen load

BACKGROUND

B cells play an important role in allergies through secretion of IgE. IL-4 receptor α (IL-4Rα) is key in allergic asthma and regulates type 2 cytokine production, IgE secretion, and airway hyperresponsiveness. IL-4 activation of B cells is essential for class switching and contributes to the induction of B effector 2 (Be2) cells. The role of Be2 cells and signaling via IL-4Rα in B cells is not clearly defined.

OBJECTIVE

We sought to find out whether IL-4Rα-responsive B cells or Be2 function was essential in experimental allergic asthma.

METHODS

Mice lacking IL-4Rα on B cells (mb1^creIL-4Rα^-/lox) or littermate controls (IL-4Rα^-/lox) and mice lacking IL-4 or IL-4/IL-13 on B cells were sensitized and challenged with high-dose house dust mite (>10 μg) or with low-dose house dust mite (<3 μg). We also adoptively transferred naive IL-4Rα^-/lox or IL-4Rα^-/- B cells into μMT^-/- mice a day before sensitization or a day before challenge. We analyzed lung inflammation, cellular infiltrate, and airway hyperresponsiveness.

RESULTS

We found that IL-4Rα signaling on B cells was important for optimal T_H2 allergic immune responses mainly when the load of antigen is limited. IL-4Rα signaling on B cells was essential for germinal centers and in the effector phase of allergic responses. Be2 cells were essential in airway hyperresponsiveness, but not in other parameters.

CONCLUSIONS

IL-4Rα signaling on B cells is deleterious in allergic asthma because it is required for optimal T_H2 responses, Be2 function, germinal center formation, and T follicular helper cells, especially when the load of the antigen is limiting.

Influenza in High-Risk Hosts-Lessons Learned from Animal Models

Factoring significantly into the global burden of influenza disease are high-risk populations that suffer the bulk of infections. Classically, the very young, very old, and pregnant women have been identified as high-risk populations; however, recent research has uncovered several other conditions that contribute to severe infection. By using varied animal models, researchers have identified molecular mechanisms underpinning the increased likelihood for infection due to obesity and malnourishment, as well as insight into the role sex hormones play in antiviral immunity in males, in females, and across the life span. Additionally, novel comorbidity models have helped elucidate the role of chronic infectious and genetic diseases in influenza virus pathogenesis. Animal models play a vital role in understanding the contribution of host factors to influenza severity and immunity. An in-depth understanding of these host factors represents an important step in reducing the burden of influenza among the growing number of people living with one or more chronic medical conditions.

IL-4Rα signaling in CD4+CD25+FoxP3+ T regulatory cells restrains airway inflammation via limiting local tissue IL-33

Impaired tolerance to innocuous particles during allergic asthma has been linked to increased plasticity of FoxP3+ regulatory T cells (Tregs) reprogramming into pathogenic effector cells, thus exacerbating airway disease. However, failure of tolerance mechanisms is driven by Th2 inflammatory signals. Therefore, the in vivo role of canonical IL-4 receptor α (IL-4Rα) signaling, an essential driver of Th2-type airway responses to allergens, on the regulatory function of FoxP3+ Tregs in allergic asthma was explored. Here, we used transgenic Foxp3cre IL-4Rα-/lox and littermate control mice to investigate the role of IL-4 and IL-13 signaling via Tregs in house dust mite-induced (HDM-induced) allergic airway disease. We sensitized mice intratracheally on day 0, challenged them on days 6-10, and analyzed airway hyperresponsiveness (AHR), airway inflammation, mucus production, and cellular profile on day 14. In the absence of IL-4Rα responsiveness on FoxP3+ Tregs, exacerbated AHR and airway inflammation were shown in HDM-sensitized mice. Interestingly, reduced induction of FoxP3+ Tregs accompanied increased IL-33 alarmin production and type 2 innate lymphoid cell activation in the lung, exacerbating airway hyperreactivity and lung eosinophilia. Taken together, our findings indicate that IL-4Rα-unresponsive FoxP3+ Tregs result in exaggerated innate Th2-type, IL-33-dependent airway inflammation and a break in tolerance during allergic asthma.

Mimicking Antigen-Driven Asthma in Rodent Models-How Close Can We Get?

Asthma is a heterogeneous disease with increasing prevalence worldwide characterized by chronic airway inflammation, increased mucus secretion and bronchial hyperresponsiveness. The phenotypic heterogeneity among asthmatic patients is accompanied by different endotypes, mainly Type 2 or non-Type 2. To investigate the pathomechanism of this complex disease many animal models have been developed, each trying to mimic specific aspects of the human disease. Rodents have classically been employed in animal models of asthma. The present review provides an overview of currently used Type 2 vs. non-Type 2 rodent asthma models, both acute and chronic. It further assesses the methods used to simulate disease development and exacerbations as well as to quantify allergic airway inflammation, including lung physiologic, cellular and molecular immunologic responses. Furthermore, the employment of genetically modified animals, which provide an in-depth understanding of the role of a variety of molecules, signaling pathways and receptors implicated in the development of this disease as well as humanized models of allergic inflammation, which have been recently developed to overcome differences between the rodent and human immune systems, are discussed. Nevertheless, differences between mice and humans should be carefully considered and limits of extrapolation should be wisely taken into account when translating experimental results into clinical use.

miR-142-5p and miR-130a-3p regulate pulmonary macrophage polarization and asthma airway remodeling

Macrophages are key regulators of the development and progression of asthma, facilitating deleterious airway remodeling in affected patients. Immune cell function is tightly regulated by microRNAs (miRNAs), but how these miRNAs impact macrophage-mediated airway remodeling in the context of asthma remains to be determined. In this study, we utilized an ovalbumin (OVA)-based murine model of asthma to evaluate the importance of miRNAs within these macrophages. We found that macrophages from mice that had been sensitized with and exposed to OVA expressed higher levels of M2-like phenotypic markers and exhibited significantly altered expression of both miR-142-5p and miR-130a-3p. When these isolated pulmonary macrophages were cultured in vitro, we determined that transfecting them with miR-142-5p antisense oligonucleotide (ASO) or miR-130a-3p mimics was sufficient to inhibit the ability of interleukin-4 to induce M2 cytokine production. We additionally confirmed the in vivo relevance of these miRNAs in a Ccr2^-/- murine model system mimicking asthma. Specifically, we determined that transfecting monocytes with miR-142-5p ASO and/or miR-130a-3p mimics was sufficient to disrupt the ability of these cells to promote airway remodeling. As such, these findings reveal that miR-142-5p and miR-130a-3p dysregulation are important factors governing the polarization of macrophages and associated airway remodeling in OVA-sensitized mice.

Alternaria alternata Accelerates Loss of Alveolar Macrophages and Promotes Lethal Influenza A Infection

Chronic inhalation of fungi and fungal components has been linked to the development of respiratory disorders, although their role with respect to the pathogenesis of acute respiratory virus infection remains unclear. Here, we evaluate inflammatory pathology induced by repetitive administration of a filtrate of the ubiquitous fungus, Alternaria alternata, and its impact on susceptibility to infection with influenza A. We showed previously that A. alternata at the nasal mucosae resulted in increased susceptibility to an otherwise sublethal inoculum of influenza A in wild-type mice. Here we demonstrate that A. alternata-induced potentiation of influenza A infection was not dependent on fungal serine protease or ribonuclease activity. Repetitive challenge with A. alternata prior to virus infection resulted proinflammatory cytokines, neutrophil recruitment, and loss of alveolar macrophages to a degree that substantially exceeded that observed in response to influenza A infection alone. Concomitant administration of immunomodulatory Lactobacillus plantarum, a strategy shown previously to limit virus-induced inflammation in the airways, blocked the exaggerated lethal response. These observations promote an improved understanding of severe influenza infection with potential clinical relevance for individuals subjected to continuous exposure to molds and fungi.

Fermented Platycodon grandiflorum Extracts Relieve Airway Inflammation and Cough Reflex Sensitivity In Vivo

Platycodon grandiflorum (PG) has been extensively utilized as an herb to relieve phlegm. In this study, the effects of PG root extracts on airway inflammation and cough reflex were investigated, especially using fermented PG extracts (FPE) to increase an active compound, platycodin D by fermentation. FPE significantly reduced the numbers of eosinophils and total cells in the bronchoalveolar lavage fluid (BALF) obtained from lipopolysaccharide/ovalbumin (LPS/OVA)-induced asthma mice versus those of vehicle control. Moreover, in the BALF and the serum, FPE significantly reduced the concentration of IL-17E, a proinflammatory cytokine that causes T_H2 immunity, including eosinophil amplification. It was also demonstrated that FPE might relieve inflammations through histological analysis of the lung separated from each mouse. Furthermore, in cough reflex guinea pigs induced by citric acid treatment, FPE treatment significantly reduced the number of coughs versus that of vehicle control, and consequently decreased cough reflex sensitivity. In addition, the total cell number and eosinophils significantly decreased in the BALF obtained from each guinea pig versus that of vehicle control. In in vitro study, pretreatment with FPE in LPS-stimulated RAW264.7 cells significantly reduced the levels of proinflammatory cytokines such as TNF-α, IL-6, and IL-1β, and inducible nitric oxide synthases (iNOS). Therefore, we demonstrated that FPE relieved airway inflammation and cough reflex sensitivity in vivo, and exhibited anti-inflammatory effects through suppression of iNOS and several proinflammatory cytokines. These findings suggest that FPE might have a beneficial effect on respiratory health, and may be useful as a functional food to prevent respiratory diseases.

Are We Meeting the Promise of Endotypes and Precision Medicine in Asthma?

While the term asthma has long been known to describe heterogeneous groupings of patients, only recently have data evolved which enable a molecular understanding of the clinical differences. The evolution of transcriptomics (and other 'omics platforms) and improved statistical analyses in combination with large clinical cohorts opened the door for molecular characterization of pathobiologic processes associated with a range of asthma patients. When linked with data from animal models and clinical trials of targeted biologic therapies, emerging distinctions arose between patients with and without elevations in type 2 immune and inflammatory pathways, leading to the confirmation of a broad categorization of type 2-Hi asthma. Differences in the ratios, sources, and location of type 2 cytokines and their relation to additional immune pathway activation appear to distinguish several different (sub)molecular phenotypes, and perhaps endotypes of type 2-Hi asthma, which respond differently to broad and targeted anti-inflammatory therapies. Asthma in the absence of type 2 inflammation is much less well defined, without clear biomarkers, but is generally linked with poor responses to corticosteroids. Integration of "big data" from large cohorts, over time, using machine learning approaches, combined with validation and iterative learning in animal (and human) model systems is needed to identify the biomarkers and tightly defined molecular phenotypes/endotypes required to fulfill the promise of precision medicine.

TLR2 favors OVA-induced allergic airway inflammation in mice through JNK signaling pathway with activation of autophagy

AIMS

Numerous studies indicate that toll-like receptor 2 (TLR2) led to divergent effects in asthma. The occurrence of autophagy in asthma pathogenesis is still incompletely understood. Here, we aimed to investigate the role of TLR2 and the underlying mechanisms in allergic airway inflammation and autophagy activation.

MAIN METHODS

C57BL/6 and TLR2 knockout (TLR2^-/-) mice were subjected to an ovalbumin (OVA)-immunized allergic airway model, and were treated with SP600125. Differential cell counts in bronchoalveolar lavage fluid were determined by Wright's staining. Histological analysis of airway inflammation was determined by haematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining. The levels of OVA-specific immunoglobulin E (IgE), tumor necrosis factor α (TNF-α) and interleukin 10 (IL-10) were detected by enzyme-linked immunosorbent assay (ELISA). Proteins expression in lung tissues was detected by western blot, expression of TLR2 was further observed by immunofluorescence. Autophagy activation was determined by western blot and transmission electron microscopy (TEM).

KEY FINDINGS

TLR2 expression was increased upon OVA challenge, and TLR2 deficiency was associated with decreased allergic airway inflammation. Meanwhile, TLR2 deficiency weakened autophagy activation. Moreover, inhibition of c-Jun N-terminal kinase (JNK) by SP600125 also suppressed OVA-induced allergic airway inflammation and autophagy activation. Interestingly, treating TLR2^-/- mice with SP600125 showed similar OVA-induced allergic airway inflammation and autophagy activation compared to that in vehicle-treated TLR2^-/- mice.

SIGNIFICANCE

TLR2 might contribute to the maintenance of allergic airway inflammation through JNK signaling pathway accompanying with autophagy activation. These findings may provide a novel signal target for prevention of allergic airway inflammation.

Identification of critical genes associated with the development of asthma by co-expression modules construction

INTRODUCTION

Asthma is a worldwide problem that is caused by complex underlying immune dysregulation. The identification of potential prognostic markers of asthma may provide information for treatment. The purpose of this study was to explore the key mechanisms involved in the development of asthma on the basis of microarray analysis.

METHODS

The expression profile data of GSE43696, which contains 20 endobronchial epithelial brushing samples from healthy patients and 88 from asthma patients, were obtained from Gene Expression Omnibus. For the present study, we built co-expression modules by weighted gene co-expression network analysis (WGCNA). This new analysis strategy was applied to the data set to investigate the relationships underlying the modules and the pathogenesis of asthma. Functional enrichment analysis was performed on these co-expression genes from the modules, and a gene network was then constructed. In addition, mouse models of HDM-induced and OVA-induced asthma were established, and the expression of hub genes was measured.

RESULTS

First, using WGCNA, 20 co-expression modules were constructed with 19,596 genes obtained from 108 human endobronchial epithelial brushing samples. The number of genes within the modules ranged from 41 to 845. According to the colours assigned by the system, the module positively correlated with asthma status was named 'red module', and the module positively correlated with asthma severity was named 'purple module'. The results of a functional enrichment analysis showed that the red module was mainly enriched in intracellular calcium-activated chloride channel activity, intracellular chloride channel activity and endopeptidase inhibitor activity. The purple module was mainly enriched in microtubule motor activity and microtubule-binding and motor activity. Moreover, the mRNA expression levels of the 15 hub genes were confirmed to be significantly upregulated in the HDM mouse model, and 12 hub genes were upregulated in the OVA model.

CONCLUSIONS

The hub genes ANO7, PYCR1 and UBE2C might play potential roles in the pathogenesis of asthma. Our findings provided a framework of co-expression gene modules of asthma and led to the identification of some new markers that might be potential targets for the development of new drugs and diagnostic markers.

YKL-40 mediates airway remodeling in asthma via activating FAK and MAPK signaling pathway

YKL-40 is a chitinase-like protein which was significantly elevated in asthma patients and related closely to asthma severity and airway remodeling. Airway remodeling in asthma involves complicated physical and pathological processes, including increased airway smooth muscle mass due to proliferation, migration of airway smooth muscle cells, epithelial-mesenchymal transition (EMT) and sub-epithelial fibrosis. However, the precise effect and underlying mechanism of YKL-40 in this pathological alteration remained unelucidated. In this study, we demonstrated that YKL-40 could promote asthma airway remodeling by increasing airway smooth muscle mass, inducing EMT and sub-epithelial fibrosis. Furthermore, we identified that FAK and MAPK signaling pathways are activated in the process. Inhibiting FAK or MAPK pathway could significantly ameliorate airway remodeling induced by excessive secretion of YKL-40 in vitro. and in vivo. In conclusion, this study shed light upon the effects of YKL-40 in asthma airway remodeling and provided potential novel targets in asthma patients with high YKL-40 level.

Plasmacytoid dendritic cell deficiency in neonates enhances allergic airway inflammation via reduced production of IFN-α

Allergic asthma, a chronic inflammatory airway disease associated with type 2 cytokines, often originates in early life. Immune responses at an early age exhibit a Th2 cell bias, but the precise mechanisms remain elusive. Plasmacytoid dendritic cells (pDCs), which play a regulatory role in allergic asthma, were shown to be deficient in neonatal mice. We report here that this pDC deficiency renders neonatal mice more susceptible to severe allergic airway inflammation than adult mice in an OVA-induced experimental asthma model. Adoptive transfer of pDCs or administration of IFN-α to neonatal mice prevented the development of allergic inflammation in wild type but not in IFNAR1^-/- mice. Similarly, adult mice developed more severe allergic inflammation when pDCs were depleted. The protective effects of pDCs were mediated by the pDC-/IFN-α-mediated negative regulation of the secretion of epithelial cell-derived CCL20, GM-CSF, and IL-33, which in turn impaired the recruitment of cDC2 and ILC2 cells to the airway. In asthmatic patients, the percentage of pDCs and the level of IFN-α were lower in children than in adults. These results indicate that impairment of pDC-epithelial cell crosstalk in neonates is a susceptibility factor for the development of allergen-induced allergic airway inflammation.