IL-13 is a central mediator of chemical-induced airway hyperreactivity in mice

GLUT1 mediates bronchial epithelial E-cadherin disruption in TDI-induced steroid-insensitive asthma

Down-regulation of bronchial epithelial E-cadherin is an important of feature of severe asthma, including steroid-insensitive asthma. Yet, the mechanisms involved in E-cadherin disruption are not fully understood. This study was aimed to investigate the role of glucose transporter 1 (GLUT1) in dysregulation of E-cadherin in toluene diisocyanate (TDI)-induced steroid-insensitive asthma. A murine model of steroid-insensitive asthma was established by TDI sensitization and aerosol inhalation. Selective GLUT1 antagonists WZB117 and BAY876 were given to BALB/c mice after airway challenge. In vitro, primary human bronchial epithelial cells (HBECs) cultured in an airway-liquid interface (ALI) were exposed to TDI. TDI exposure markedly up-regulated GLUT1 in murine lungs and HBECs. Pharmacological inhibition of GLUT1 with BAY876 decreased airway hyperresponsiveness, neutrophil and eosinophil accumulation, as well as type 2 inflammation in vivo. Besides, the TDI-induced down-regulated expression of full-length E-cadherin was also partly recovered, accompanied by inhibited secretion of soluble E-cadherin (sE-cadherin). WZB117 also exhibited mild therapeutic effects, though not significant. In vitro, treatment with GLUT1 inhibitor relieved the TDI-induced disruption of E-cadherin in HBECs. Taken together, our data demonstrated that GLUT1 modulates bronchial epithelial E-cadherin dysfunction production in TDI-induced steroid-insensitive asthma.

Exercise Reduces Airway Smooth Muscle Contraction in Asthmatic Rats via Inhibition of IL-4 Secretion and Store-Operated Ca2+ Entry Pathway

PURPOSE

Increased evidence has shown that aerobic exercise reduces airway hyperresponsiveness in asthmatic individuals. However, the underlying mechanisms of action remain elusive. This study aimed to investigate the effect of exercise on airway smooth muscle (ASM) contractile function in asthmatic rats, and uncover the possible involvement of interleukin 4 (IL-4) and the store-operated Ca²⁺ entry (SOCE) pathway.

METHODS

In this study, chicken ovalbumin was used to induce asthma in male Sprague-Dawley rats. The exercise group received moderate-intensity aerobic exercise training for 4 weeks. IL-4 concentrations in bronchoalveolar lavage fluid (BALF) samples were evaluated by enzyme linked immunosorbent assay. The contractile function of the ASM was investigated using tracheal ring tension experiments and intracellular Ca²⁺ imaging techniques. Western blot analysis was used to evaluate expression levels of calcium-release activated calcium (CRAC) channel protein (Orai) and stromal interaction molecule 1 (STIM1) in ASM.

RESULTS

Our data showed that the carbachol-stimulated, SOCE-mediated contraction of rat ASM was significantly increased in asthmatic rats, which could be abolished by exercise. Pharmacological studies revealed that GSK5498A and BTP-2, selective blockers of CRAC channels significantly inhibited SOCE-induced ASM contraction. In addition, exercise inhibited the up-regulation of IL-4 in BALF as well as STIM1 and Orai expression in the ASM of asthmatic rats. In line with these observations, we demonstrated that pretreatment of the ASM with IL-4 up-regulated the expression level of STIM1, Orai1 and Orai2, thereby promoting SOCE-mediated ASM contraction.

CONCLUSIONS

The data in this study reveal that aerobic exercise may improve the ASM contractile function in asthmatic rats by inhibiting IL-4 secretion and by down-regulating the expression of STIM1, Orai1 and Orai2, thus decreasing excessive SOCE-mediated ASM contraction in asthmatic rats.

Peribronchial Inflammation Resulting from Regulatory T Cell Deficiency Damages the Respiratory Epithelium and Disturbs Barrier Function

Regulatory T cells (Tregs) that express the transcription factor Foxp3 have a critical role in limiting inflammatory processes and tissue damage. Whether Tregs are functional in maintaining epithelial barriers and in control of tight junction expression has not yet been explored. In this study, we investigated the effect of Treg deficiency on the airway epithelial barrier in an experimental murine model in which diphtheria toxin was repeatedly injected in Foxp3-diphtheria toxin receptor (DTR) mice to deplete Tregs. This resulted in spontaneous peribronchial inflammation and led to a systemic and local increase of IL-4, IL-5, CCL3, IFN-γ, and IL-10 and a local (lung) increase of IL-6 and IL-33 and decreased amphiregulin levels. Moreover, Treg depletion increased airway permeability and decreased epithelial tight junction (protein and mRNA) expression. CTLA4-Ig treatment of Treg-depleted mice almost completely prevented barrier dysfunction together with suppression of lung inflammation and cytokine secretion. Treatment with anti–IL-4 partly reversed the effects of Treg depletion on tight junction expression, whereas neutralization of IL-6 of IFN-γ had either no effect or only a limited effect. We conclude that Tregs are essential to protect the epithelial barrier at the level of tight junctions by restricting spontaneous T cell activation and uncontrolled secretion of cytokines, in particular IL-4, in the bronchi.

Oxidant-induced epithelial alarmin pathway mediates lung inflammation and functional decline following ultrafine carbon and ozone inhalation co-exposure

Environmental inhalation exposures are inherently mixed (gases and particles), yet regulations are still based on single toxicant exposures. While the impacts of individual components of environmental pollution have received substantial attention, the impact of inhalation co-exposures is poorly understood. Here, we mechanistically investigated pulmonary inflammation and lung function decline after inhalation co-exposure and individual exposures to ozone (O₃) and ultrafine carbon black (CB). Environmentally/occupationally relevant lung deposition levels in mice were achieved after inhalation of stable aerosols with similar aerodynamic and mass median distributions. X-ray photoemission spectroscopy detected increased surface oxygen contents on particles in co-exposure aerosols. Compared with individual exposures, co-exposure aerosols produced greater acellular and cellular oxidants detected by electron paramagnetic resonance (EPR) spectroscopy, and in vivo immune-spin trapping (IST), as well as synergistically increased lavage neutrophils, lavage proteins and inflammation related gene/protein expression. Co-exposure induced a significantly greater respiratory function decline compared to individual exposure. A synthetic catalase-superoxide dismutase mimetic (EUK-134) significantly blunted lung inflammation and respiratory function decline confirming the role of oxidant imbalance. We identified a significant induction of epithelial alarmin (thymic stromal lymphopoietin-TSLP)-dependent interleukin-13 pathway after co-exposure, associated with increased mucin and interferon gene expression. We provided evidence of interactive outcomes after air pollution constituent co-exposure and identified a key mechanistic pathway that can potentially explain epidemiological observation of lung function decline after an acute peak of air pollution. Developing and studying the co-exposure scenario in a standardized and controlled fashion will enable a better mechanistic understanding of how environmental exposures result in adverse outcomes.

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Interaction with O₃ mediates free radical production on the surface of carbon black (CB) particles.

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Oxidants mediate co-exposure (CB + O₃)-induced lung function decline.

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EUK-134 (a synthetic superoxide-catalase mimetic) abrogates CB + O₃-induced lung inflammation.

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CB + O₃ co-exposure induces greater lung inflammation than individual exposures.

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Epithelial alarmin (TSLP) contributes significantly to the CB + O₃ toxicity.

Identification and biochemical characterization of Asp t 36, a new fungal allergen from Aspergillus terreus

Aspergillus terreus is an allergenic fungus, in addition to causing infections in both humans and plants. However, the allergens in this fungus are still unknown, limiting the development of diagnostic and therapeutic strategies. We used a proteomic approach to search for allergens, identifying 16 allergens based on two-dimensional immunoblotting with A. terreus susceptible patient sera. We further characterized triose-phosphate isomerase (Asp t 36), one of the dominant IgE (IgE)-reactive proteins. The gene was cloned and expressed in Escherichia coli. Phylogenetic analysis showed Asp t 36 to be highly conserved with close similarity to the triose-phosphate isomerase protein sequence from Dermatophagoides farinae, an allergenic dust mite. We identified four immunodominant epitopes using synthetic peptides, and mapped them on a homology-based model of the tertiary structure of Asp t 36. Among these, two were found to create a continuous surface patch on the 3D structure, rendering it an IgE-binding hotspot. Biophysical analysis indicated that Asp t 36 shows similar secondary structure content and temperature sensitivity with other reported triose-phosphate isomerase allergens. In vivo studies using a murine model displayed that the recombinant Asp t 36 was able to stimulate airway inflammation, as demonstrated by an influx of eosinophils, goblet cell hyperplasia, elevated serum Igs, and induction of Th2 cytokines. Collectively, our results reveal the immunogenic property of Asp t 36, a major allergen from A. terreus, and define a new fungal allergen more broadly. This allergen could serve as a potent candidate for investigating component resolved diagnosis and immunotherapy.

Involvement of Innate Lymphoid Cells and Dendritic Cells in a Mouse Model of Chemical-induced Asthma

PURPOSE

Exposure to low concentrations of toluene diisocyanate (TDI) leads to immune-mediated chemical-induced asthma. The role of the adaptive immune system has already been thoroughly investigated; nevertheless, the involvement of innate immune cells in the pathophysiology of chemical-induced asthma is still unresolved. The aim of the study is to investigate the role of innate lymphoid cells (ILCs) and dendritic cells (DCs) in a mouse model for chemical-induced asthma.

METHODS

On days 1 and 8, BALB/c mice were dermally treated (20 μL/ear) with 0.5% TDI or the vehicle acetone olive oil (AOO; 2:3). On days 15, 17, 19, 22 and 24, the mice received an oropharyngeal challenge with 0.01% TDI or AOO (1:4). One day after the last challenge, airway hyperreactivity (AHR) to methacholine was assessed, followed by an evaluation of pulmonary inflammation and immune-related parameters, including the cytokine pattern in bronchoalveolar lavage fluid, lymphocyte subpopulations of the lymph nodes and their ex vivo cytokine production profile, blood immunoglobulins and DC and ILC subpopulations in the lungs.

RESULTS

Both DC and ILC2 were recruited to the lungs after multiple airway exposures to TDI, regardless of the prior dermal sensitization. However, prior dermal sensitization with TDI alone results in AHR and predominant eosinophilic airway inflammation, accompanied by a typical type 2 helper T (Th2) cytokine profile.

CONCLUSIONS

TDI-induced asthma is mediated by a predominant type 2 immune response, with the involvement of adaptive Th2 cells. However, from our study we suggest that the innate ILC2 cells are important additional players in the development of TDI-induced asthma.

The association between IL18, FOXP3 and IL13 genes polymorphisms and risk of allergic rhinitis: a meta-analysis

OBJECTIVES

Allergic rhinitis (AR) is a chronic inflammatory disease of nasal mucosa. Loss of function of Th17 cells and regulatory T (Treg) cells plays a role in the pathogenesis of AR. IL18, FOXP3, and IL13 are key genes in the development of AR. However, the genetic associations between IL18, FOXP3 and IL13 genes polymorphisms and AR risk were inconclusive yet.

METHODS

A meta-analysis was performed by searching through Pubmed, EMBASE, web of science and CNKI databases. The ORs and 95%CIs were used to assess the genetic association between the allelic, dominant and recessive models of IL18, FOXP3 and IL13 genes polymorphisms and AR risk.

RESULTS

A total of 15 articles (6 for FOXP3, 5 for IL18, and 5 for IL13) were enrolled in the present study. No association was detected between the IL18 rs187238, rs1946518, rs360721, FOXP3 rs2232365, rs3761548 and IL13 rs1800925 polymorphisms and AR risk (p > 0.05). Significant associations were observed between the allelic (p = 0.001, OR 1.32, 95% CI 1.12-1.56), dominant (p = 0.005, OR 1.43, 95% CI 1.11-1.83) and recessive models (p = 0.01, OR 1.64, 95% CI 1.13, 2.40) of IL13 rs20541 and AR risk. Subgroup analysis based on ethnicity revealed that the IL13 rs20541 was significantly associated with AR risk in Asian population (allelic model: p = 0.009, OR 1.36, 95% CI 1.13-1.63, dominant model: p = 0.005, OR 1.43, 95% CI 1.11-1.83; recessive model: p = 0.01, OR 1.64, 95% CI 1.13-2.40).

CONCLUSIONS

IL13 rs20541 may contribute to the risk of AR in Asian population. To confirm these results, larger number of case-control study with more subjects is necessary in the future.

Driver Mutations in Leukemia Promote Disease Pathogenesis through a Combination of Cell-Autonomous and Niche Modulation

Studies of patients with acute myeloid leukemia (AML) have led to the identification of mutations that affect different cellular pathways. Some of these have been classified as preleukemic, and a stepwise evolution program whereby cells acquire additional mutations has been proposed in the development of AML. How the timing of acquisition of these mutations and their impact on transformation and the bone marrow (BM) microenvironment occurs has only recently begun to be investigated. We show that constitutive and early loss of the epigenetic regulator, TET2, when combined with constitutive activation of FLT3, results in transformation of chronic myelomonocytic leukemia-like or myeloproliferative neoplasm-like phenotype to AML, which is more pronounced in double-mutant mice relative to mice carrying mutations in single genes. Furthermore, we show that in preleukemic and leukemic mice there are alterations in the BM niche and secreted cytokines, which creates a permissive environment for the growth of mutation-bearing cells relative to normal cells.

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Ubiquitous loss of Tet2 followed by expression of Flt3^ITD/ITD results in lethal AML

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Tet2^−/− cells when exposed to leukemic environment manifest MPN-like features

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Hyperproliferation of Flt3^ITD donor cells in preleukemic Tet2^−/− microenvironment

Bifidobacterium infantis Relieves Allergic Asthma in Mice by Regulating Th1/Th2

Background

Bifidobacteria are among the probiotics used in treating intestinal diseases and are rarely used for allergic asthma treatment. The present study investigated the mechanism of B. infantis in treating allergic asthma in mice.

Material/Methods

A total of 40 male Balb/c mice were randomized into control, ovalbumin (OVA), montelukast (Mon), and B. infantis (B10) groups, and allergic asthma was induced in the OVA, Mon, and B10 groups. Airway reactivity was measured on day 29 by methacholine at various doses. The numbers of total cells and inflammatory cells in bronchoalveolar lavage fluid (BALF) were counted by blood cell counter and Diff-Quik staining. Hematoxylin-eosin (HE) staining was performed to observe inflammatory cell infiltration in lung tissues. Total IgE and OVA-specific IgE in serum were measured by ELISA. Mucin 5AC expression was detected by Western blot to evaluate airway obstruction. The levels of Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-5, IL-13) cytokines in BALF and tissues were detected by ELISA and qRT-PCR, respectively.

Results

The mice in the OVA group had airway hyperreactivity, while the symptoms in the B10 group and Mon group were effectively relieved. B10 reduced the number of inflammatory cells in BALF as well as inflammatory cell infiltration in tissues. Moreover, the levels of total serum IgE, OVA-specific IgE, and Mucin 5AC were increased in the OVA group, but were reduced in the Mon group and B10 group. B. infantis increased the levels of Th1 cytokines and decreased those of Th2 cytokines.

Conclusions

B. infantis can reduce the infiltration of inflammatory cells induced by OVA-specific antibodies in mice. B. infantis has therapeutic effects on allergic asthma by promoting Th1 and inhibiting Th2 immune responses.

2-Aminoethyldiphenyl Borinate: A Multitarget Compound with Potential as a Drug Precursor

BACKGROUND

Boron is considered a trace element that induces various effects in systems of the human body. However, each boron-containing compound exerts different effects.

OBJECTIVE

To review the effects of 2-Aminoethyldiphenyl borinate (2-APB), an organoboron compound, on the human body, but also, its effects in animal models of human disease.

METHODS

In this review, the information to showcase the expansion of these reported effects through interactions with several ion channels and other receptors has been reported. These effects are relevant in the biomedical and chemical fields due to the application of the reported data in developing therapeutic tools to modulate the functions of the immune, cardiovascular, gastrointestinal and nervous systems.

RESULTS

Accordingly, 2-APB acts as a modulator of adaptive and innate immunity, including the production of cytokines and the migration of leukocytes. Additionally, reports show that 2-APB exerts effects on neurons, smooth muscle cells and cardiomyocytes, and it provides a cytoprotective effect by the modulation and attenuation of reactive oxygen species.

CONCLUSION

The molecular pharmacology of 2-APB supports both its potential to act as a drug and the desirable inclusion of its moieties in new drug development. Research evaluating its efficacy in treating pain and specific maladies, such as immune, cardiovascular, gastrointestinal and neurodegenerative disorders, is scarce but interesting.