TLR2-ERK signaling pathway regulates expression of galectin-3 in a murine model of OVA-induced allergic airway inflammation

Toll-like receptor 2 (TLR2) and galectin-3 (Gal-3) are involved in the pathological process of asthma, but the underlying mechanism is not fully understood. We hypothesized that TLR2 pathway may regulate expression of Gal-3 in allergic airway inflammation. Wild-type (WT) and TLR2-/- mice were sensitized on day 0 and challenged with ovalbumin (OVA) on days 14-21 to establish a model of allergic airway inflammation, and were treated with a specific ERK inhibitor U0126. Histological changes in the lungs were analyzed by hematoxylin-eosin (HE) and Periodic Acid-Schiff (PAS) staining; cytokines and anti-OVA immunoglobulin E (IgE) were tested by ELISA; and related protein expression in lung tissues was measured by western blot. We found that the expression levels of TLR2 and Gal-3 markedly increased concomitantly with airway inflammation after OVA induction, while TLR2 deficiency significantly alleviated airway inflammation and reduced Gal-3 expression. Moreover, the expression levels of phosphorylated mitogen-activated protein kinases (p-MAPKs) were significantly elevated in OVA-challenged WT mice, while TLR2 deficiency only significantly decreased phosphorylated extracellular signal-regulated kinase (p-ERK) levels. Furthermore, we found that U0126 treatment significantly alleviated allergic airway inflammation and decreased Gal-3 levels in OVA-challenged WT mice, but had no further effect in OVA-challenged TLR2-/- mice. These above results suggested that TLR2 is an upstream signal molecule of ERK. We further demonstrated that TLR2 regulates Gal-3 expression through the ERK pathway in LTA-stimulated macrophages in vitro. Our findings showed that the TLR2-ERK signaling pathway regulates Gal-3 expression in a murine model of allergic airway inflammation.

Melatonin regulates circadian clock proteins expression in allergic airway inflammation

Asthma demonstrates a strong circadian rhythm with disrupted molecular clock. Melatonin which can directly regulate circadian rhythm has been reported to alleviate asthma, but whether this effect is related to its regulation on circadian clock has not yet been known. Here, female C57BL/6 mice were challenged with ovalbumin (OVA) to establish allergic airway inflammation, and were treated with melatonin or Luzindole to investigate whether the expressions of circadian clock proteins were changed in response to OVA and were affected by exogenous/endogenous melatonin. Airway inflammation, mucus secretion, protein expressions of circadian proteins (Bmal1, Per1, Clock, Timeless, Cry1 and Cry2), melatonin biosynthetase (ASMT, AANAT) and melatonin receptor (Mel-1A/B-R) were analyzed accordingly. The results showed that in the successfully established allergic airway inflammation model, inflammatory cells infiltration, expressions of circadian clock proteins in the lung tissues of OVA-challenged mice were all notably up-regulated as compared to that of the vehicle mice. Meanwhile, the protein expression of ASMT and the level of melatonin in the lung tissues were reduced in allergic mice, while the expression of melatonin receptor Mel-1A/B-R was markedly increased. After addition of exogenous melatonin, the OVA-induced airway inflammation was pronouncedly ameliorated, while simultaneously the OVA-induced expressions of Per1 and Clock were further increased. However, a melatonin receptor antagonist Luzindole further augmented the OVA-induced airway inflammation, accompanied with remarkably decreased expressions of Per1, Bmal1, Cry1 and Cry2 but notably increased expression of Timeless. Collectively, our results demonstrated that the expression of circadian clock proteins was increased in the lungs during allergic airway inflammation, and Per1 was a clock protein that can be regulated by both exogenous and endogenous melatonin, suggesting Per1 may be an important potential circadian clock target for melatonin as a negative regulatory factor against Th2-type airway inflammation.

Therapeutic potential of mesenchymal stem cell-derived exosomes for allergic airway inflammation

Due to their immunomodulatory capacities, mesenchymal stem cells (MSCs) have been extensively used as therapeutic approaches in cell-based therapy for various inflammatory diseases. Several lines of studies have shown that the most beneficial effects of MSCs are associated with MSC-derived exosomes. Exosomes are nanoscale extracellular vesicles that contain important biomolecules such as RNA, microRNAs (miRNAs), DNA, growth factors, enzymes, chemokines, and cytokines that regulate immune cell functions and parenchymal cell survival. Recently, exosomes, especially MSC-derived exosomes, have been shown to have protective effects in allergic airway inflammation. This review focused on the immune-regulatory potential of MSC-derived exosomes as nanoscale delivery systems in the treatment of allergic airway inflammation.

Mesenchymal stem cells overexpressing interleukin-10 prevent allergic airway inflammation

BACKGROUNDS

Allergic airway inflammation is prevalent worldwide and imposes a considerable burden on both society and affected individuals. This study aimed to investigate the therapeutic advantages of mesenchymal stem cells (MSCs) overexpressed interleukin-10 (IL-10) for the treatment of allergic airway inflammation, as both IL-10 and MSCs possess immunosuppressive properties.

METHODS

Induced pluripotent stem cell (iPSC)-derived MSCs were engineered to overexpress IL-10 via lentiviral transfection (designated as IL-10-MSCs). MSCs and IL-10-MSCs were administered intravenously to mice with allergic inflammation induced by ovalbumin (OVA), and the features of allergic inflammation including inflammatory cell infiltration, Th cells in the lungs, and T helper 2 cell (Th2) cytokine levels in bronchoalveolar lavage fluid (BALF) were examined. MSCs and IL-10-MSCs were co-cultured with CD4+ T cells from patients with allergic rhinitis (AR), and the levels of Th2 cells and corresponding type 2 cytokines were studied. RNA-sequence was performed to further investigate the potential effects of MSCs and IL-10-MSCs on CD4+ T cells.

RESULTS

Stable IL-10-MSCs were established and characterised by high IL-10 expression. IL-10-MSCs significantly reduced inflammatory cell infiltration and epithelial goblet cell numbers in the lung tissues of mice with allergic airway inflammation. Inflammatory cell and cytokine levels in BALF also decreased after the administration of IL-10-MSCs. Moreover, IL-10-MSCs showed a stronger capacity to inhibit the levels of Th2 after co-cultured with CD4+ T cells from patients with AR. Furthermore, we elucidated lower levels of IL-5 and IL-13 in IL-10-MSCs treated CD4+ T cells, and blockade of IL-10 significantly reversed the inhibitory effects of IL-10-MSCs. We also reported the mRNA profiles of CD4+ T cells treated with IL-10-MSCs and MSCs, in which IL-10 played an important role.

CONCLUSION

IL-10-MSCs showed positive effects in the treatment of allergic airway inflammation, providing solid support for the use of genetically engineered MSCs as a potential novel therapy for allergic airway inflammation.

Extracellular vesicles of the probiotic bacteria E. coli O83 activate innate immunity and prevent allergy in mice

BACKGROUND

E. coli O83 (Colinfant Newborn) is a Gram-negative (G-) probiotic bacterium used in the clinic. When administered orally, it reduces allergic sensitisation but not allergic asthma. Intranasal administration offers a non-invasive and convenient delivery method. This route bypasses the gastrointestinal tract and provides direct access to the airways, which are the target of asthma prevention. G- bacteria such as E. coli O83 release outer membrane vesicles (OMVs) to communicate with the environment. Here we investigate whether intranasally administered E. coli O83 OMVs (EcO83-OMVs) can reduce allergic airway inflammation in mice.

METHODS

EcO83-OMVs were isolated by ultracentrifugation and characterised their number, morphology (shape and size), composition (proteins and lipopolysaccharide; LPS), recognition by innate receptors (using transfected HEK293 cells) and immunomodulatory potential (in naïve splenocytes and bone marrow-derived dendritic cells; BMDCs). Their allergy-preventive effect was investigated in a mouse model of ovalbumin-induced allergic airway inflammation.

RESULTS

EcO83-OMVs are spherical nanoparticles with a size of about 110 nm. They contain LPS and protein cargo. We identified a total of 1120 proteins, 136 of which were enriched in OMVs compared to parent bacteria. Proteins from the flagellum dominated. OMVs activated the pattern recognition receptors TLR2/4/5 as well as NOD1 and NOD2. EcO83-OMVs induced the production of pro- and anti-inflammatory cytokines in splenocytes and BMDCs. Intranasal administration of EcO83-OMVs inhibited airway hyperresponsiveness, and decreased airway eosinophilia, Th2 cytokine production and mucus secretion.

CONCLUSIONS

We demonstrate for the first time that intranasally administered OMVs from probiotic G- bacteria have an anti-allergic effect. Our study highlights the advantages of OMVs as a safe platform for the prophylactic treatment of allergy. Video Abstract.

Chronic intermittent hypoxia increases airway hyperresponsiveness during house dust mites exposures in rats

INTRODUCTION

Accumulating clinical evidence links Obstructive Sleep Apnea (OSA) with worse outcomes of asthma, but impact on airway function remains sparsely studied. We tested effects of Chronic Intermittent Hypoxia (CIH) - a hallmark of OSA - on airway hyperresponsiveness (AHR), in a rat model of chronic allergen-induced inflammation.

METHODS

Brown Norway rats were exposed to six weeks of CIH or normoxia (NORM) concurrent with weekly house dust mites (HDM) or saline (SAL) challenges. At endpoint, we assessed responses to seven Methacholine (Mch) doses (0, 4, 8, 16, 32, 64, 128 mg/mL) on a FlexiVent system (Scireq). Maximal (or plateau) responses (reactivity) for total respiratory system Resistance (R_rs) and Elastance (E_rs), Newtonian airway resistance (R_N, a measure of central airways function) and tissue damping (G, a measure of distal airways function) were plotted.

RESULTS

HDM/CIH-treated animals demonstrated the highest reactivity to Mch in R_rs and E_rs compared to all other groups (HDM/NORM, SAL/CIH and SAL/NORM p < 0.05 for all comparisons, for doses 5-7 for R_rs, and for doses 4-7 for E_rs). The enhanced R_rs response was due to an increase in G (doses 4-7, p < 0.05 for comparisons to all other groups), whereas R_N was not affected by CIH.

CONCLUSIONS

In rats chronically challenged with HDM, concurrent CIH exposure induces AHR primarily in the distal airways, which affects the respiratory system frequency-dependent elastic properties.

Exopolysaccharide from Lacticaseibacillus rhamnosus induces IgA production in airways and alleviates allergic airway inflammation in mouse model

The currently observed high prevalence of allergic diseases has been associated with changes in microbial exposure in industrialized countries. Defined bacterial components represent a new strategy for modulating the allergic immune response. We show that intranasal administration of exopolysaccharide (EPS) isolated from Lacticaseibacillus (L.) rhamnosus LOCK900 induces TGF-β1, IgA, and regulatory FoxP3+ T-cells in the lungs of naïve mice. Using the ovalbumin mouse model, we demonstrate that intranasal administration of EPS downregulates the development of allergic airway inflammation and the Th2 cytokine response in sensitized individuals. At the same time, EPS treatment of sensitized mice, similar to EPS-induced responses in naïve mice, significantly increased the level of total, OVA-specific, and also bacteria-specific IgA in bronchoalveolar lavage and the number of IgA-producing B-cells in the lung tissue of these mice. Thus, EPS derived from L. rhamnosus LOCK900 can be considered a safe candidate for preventing the development of allergic symptoms in the lungs of sensitized individuals upon exposure to an allergen.

Role of Mesenchymal Stem Cells and Short Chain Fatty Acids in Allergy: A Prophylactic Therapy for Future

Allergic diseases are broadly classified as IgE-mediated type-I hypersensitivity immune reactions due to exposure to typically harmless substances known as allergens. These allergenic substances activate antigen presenting cells, which further triggers T-helper 2 cells immune response and class switch B-cells for synthesis of allergen-specific IgE, followed by classical activation of inflammatory mast cells and eosinophils, which releases preformed mediators involved in the cascade of allergic symptoms. However, the role of Mesenchymal stem cells (MSCs) in tissue repair ability and immunomodulation, makes them as an appropriate tool for treatment of various allergic diseases. Several clinical and preclinical studies show that MSCs could be a promising alternative therapy to allergic diseases. Further, short chain fatty acids, produced from gut microbes by breaking down complex fibre-rich foods, acts through G-coupled receptor mediated activation of MSCs, and their role as key players involved in amelioration of allergic inflammation needs further investigation. Therefore, there is a need for understating the role of SCFAs on the activation of MSCs, which might shed light on the development of new therapeutic regime in allergy treatment. In summary, this review focuses on the underlying of therapeutic role of MSCs in different allergic diseases and the prospects of SCFA and MSC therapy.

Attenuates the allergic airway inflammation of cold asthma via inhibiting the activation of TLR4-medicated NF-kB and NLRP3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pinellia ternata (Thunb.) Breit. (PT) has been demonstrated to be effective against the allergic airway inflammation (AAI) in clinical practices, especially in cold asthma (CA). Until now, the active ingredients, protective effect, and possible mechanism of PT against CA remain unknown.

AIM OF THE STUDY

The aim of this investigation was to examine the therapeutic impact and elucidate the underlying mechanism of PT on the AAI of CA.

METHODS

The compositions of PT water extract were determined via the UPLC-Q-TOF-MS/MS. The ovalbumin (OVA) and cold-water baths were used to induce CA in female mice. Morphological characteristic observations, expectorant effect, bronchial hyperreactivity (BHR), excessive mucus secretion, and inflammatory factors were used to uncover the treatment effect of PT water extract. In addition, the mucin 5AC (MUC5AC) mRNA and protein levels and the aquaporin 5 (AQP5) mRNA and protein levels were detected via qRT-PCR, immunohistochemistry (IHC), and western blotting. Moreover, the protein expressions associated with the TLR4, NF-κB, and NLRP3 signaling pathway were monitored by western blot analysis.

RESULTS

Thirty-eight compounds were identified from PT water extract. PT showed significant therapeutic effects on mice with cold asthma in terms of expectorant activity, histopathological changes, airway inflammation, mucus secretion, and hyperreactivity. PT exhibited good anti-inflammatory effects in vitro and in vivo. The expression levels of MUC5AC mRNA and protein decreased significantly, while AQP5 expression levels increased significantly in the lung tissues of mice after administration with PT as compared to mice induced by CA. Furthermore, the protein expressions of TLR4, p-iκB, p-p65, IL-1β, IL-18, NLRP3, cleaved caspase-1, and ASC were markedly reduced following PT treatment.

CONCLUSIONS

PT attenuated the AAI of CA by modulating Th1- and Th2-type cytokines. PT could inhibit the TLR4-medicated NF-kB signaling pathway and activate the NLRP3 inflammasome to reduce CA. This study provides an alternative therapeutic agent of the AAI of CA after administration with PT.

pteronyssinus-induced allergic airway inflammation through RIP2/NF-κB

BACKGROUND

Dermatophagoides pteronyssinus (D. pteronyssinus) is the main cause of allergic airway inflammation. As the earliest intracytoplasmic pathogen recognition receptors (PRR), NOD1 has been identified as key inflammatory mediator in NOD-like receptor (NLR) family.

OBJECTIVE

Our primary aim is to elucidate whether NOD1 and its downstream regulatory proteins mediate D. pteronyssinus-induced allergic airway inflammation.

METHODS

Mouse and cell models of D. pteronyssinus-induced allergic airway inflammation were established. NOD1 was inhibited in bronchial epithelium cells (BEAS-2B cells) and mice by cell transfection or application of inhibitor. The change of downstream regulatory proteins was detected by quantitative real-time PCR (qRT-PCR) and Western blot. The relative expression of inflammatory cytokines was evaluated by ELISA.

RESULTS

The expression level of NOD1 and its downstream regulatory proteins increased in BEAS-2B cells and mice after treating with D. pteronyssinus extract, followed by the aggravation of inflammatory response. Moreover, inhibition of NOD1 decreased the inflammatory response, which also downregulated the expression of downstream regulatory proteins and inflammatory cytokines.

CONCLUSIONS

NOD1 involves in the development of D. pteronyssinus-induced allergic airway inflammation. Inhibition of NOD1 reduces D. pteronyssinus-induced airway inflammation.

Alleviates the allergic airway inflammation of cold phlegm via regulation of PKC/EGFR/MAPK/PI3K-AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pinelliae Rhizoma Praeparatum (PRP) is a traditional processed product of Pinellia ternata (Thunb.) Berit., which mainly used for treating cold asthma (CA). However, the mechanism of action of PRP for treating CA have not been fully elucidated.

AIM OF THE STUDY

To investigate the core active constituents and the pharmacological mechanism of PRP against CA.

MATERIALS AND METHODS

Ovalbumin (OVA) and cold water-induced cold asthma model were established in male mice. The effects of water extract from PRP were evaluated by general morphological observation, expectorant activity, airway hyperresponsiveness, mucus hypersecretion, inflammatory cytokines, etc. Additionally, the mRNA and protein expression of mucin 5AC (MUC5AC) and aquaporin 5 (AQP5) in vivo and in vitro were detected by immunohistochemistry (IHC), qRT-PCR, and western blotting. The mechanisms of action were investigated through network pharmacology and transcriptomic, and validated through western blotting and molecular docking.

RESULTS

PRP exhibited a favorable expectorant activity, and significantly reduced the airway inflammation, mucus secretion, and hyperresponsiveness in cold asthma model. It also reduced the levels of IL-4, IL-5, IL-8, and IL-13 in bronchoalveolar lavage fluid (BALF) and IL-4 and total IgE in serum, while obviously increased the levels of IL-10 and IFN-γ in serum for asthmatic mice. Meanwhile, PRP also attenuated the pathological changes and mucus production in cold asthmatic mice. Moreover, the downregulation of MUC5AC and upregulation of AQP 5 were detected by western blotting and qRT-PCR after administration with PRP both in vivo and in vitro. PRP expectedly inhibited the protein expression of PKC-α, SRC, p-EGFR, p-ERK1/2, p-JNK, p-p38, p-PI3K, and p-Akt levels in vivo.

CONCLUSIONS

These combined data showed that PRP suppressed the allergic airway inflammation of CA by regulating the balance of Th1 and Th2 cytokines and the possible involvement of the PKC/EGFR/MAPK/PI3K-Akt signaling pathway. Pentadecanoic acid, licochalcone A, β-sitosterol, etc. were considered as main active ingredients of PRP against CA. This study provides a novel perspective of the classical herbal processed product PRP in the treatment of CA.

Allergic airway inflammation induces upregulation of the expression of IL-23R by macrophages and not in CD3 + T cells and CD11c+F4/80- dendritic cells of the lung

Interleukin 23 and the interleukin 23 receptor (IL-23-IL23R) are described as the major enhancing factors for Interleukin 17 (IL-17) in allergic airway inflammation. IL-17 is considered to induce neutrophilic inflammation in the lung, which is often observed in severe, steroid-resistant asthma-phenotypes. For that reason, understanding of IL-23 and IL-17 axis is very important for future therapy strategies, targeting neutrophil pathway of bronchial asthma.

This study aimed to investigate the distribution and expression of IL-23R under physiological and inflammatory conditions. Therefore, a house dust mite (HDM) model of allergic airway inflammation was performed by treating mice with HDM intranasally. Immunofluorescence staining with panel of antibodies was performed in lung tissues to examine the macrophage, dendritic cell, and T cell subpopulations. The allergic airway inflammation was quantified by histopathological analysis, ELISA measurements, and airway function.

HDM-treated mice exhibited a significant allergic airway inflammation including higher amounts of NE⁺ cells in lung parenchyma. We found only a small amount of IL-23R positives, out of total CD3⁺T cells, and no upregulation in HDM-treated animals. In contrast, the populations of F4/80⁺ macrophages and CD11c⁺F4/80⁻ dendritic cells (DCs) with IL-23R expression were found to be higher. But HDM treatment leads to a significant increase of IL-23R⁺ macrophages, only. IL-23R was expressed by every examined macrophage subpopulation, whereas only Mϕ1 and hybrids between Mϕ1 and Mϕ2 phenotype and not Mϕ2 were found to upregulate IL-23R. Co-localization of IL-23R and IL-17 was only observed in F4/80⁺ macrophages, suggesting F4/80⁺ macrophages express IL-23R along with IL-17 in lung tissue.

The study revealed that macrophages involving the IL-23 and IL-17 pathway may provide a potential interesting therapeutic target in neutrophilic bronchial asthma.

Contribution of Kazal-Like Domains of the Serine Protease Inhibitor-1 from Toxoplasma gondii in Asthma Therapeutic Vaccination Effectiveness

BACKGROUND

We have previously showed rTgPI-1 tolerogenic adjuvant properties in asthma treatment, turning it a promising candidate for allergen-specific immunotherapy. This therapy is an alternative treatment to control asthma that still presents several concerns related to its formulation. rTgPI-1 contains independent inhibitory domains able to inhibit trypsin and neutrophil elastase, both involved in asthma pathology.

OBJECTIVES

In view of the need to design rational therapies, herein we investigated the contribution of the different inhibitory domains in rTgPI-1 therapeutic effectiveness.

METHODS

BALB/c mice were rendered allergic by intraperitoneal OVA-alum sensitization and airway challenged. Once the asthmatic phenotype was achieved, mice were intranasally treated with OVA combined with the full-length recombinant protein rTgPI-1 or its truncated versions, Nt (containing trypsin-inhibitory domains) or Ct (containing neutrophil elastase-inhibitory domains). Afterward, mice were aerosol re-challenged.

RESULTS

Asthmatic mice treated with the neutrophil elastase- or the trypsin-inhibitory domains separately failed to improve allergic lung inflammation. Only when all inhibitory domains were simultaneously administered, an improvement was achieved. Still, a better outcome was obtained when mice were treated with the full-length rTgPI-1.

CONCLUSIONS

Adjuvant ability depends on the presence of all its inhibitory domains in a single entity, so it should be included in potential asthma treatment formulations as a full-length protein.

Targeting Eosinophils in Mouse Models of Asthma

Eosinophils are bone marrow-derived hematopoietic cells that accumulate significantly in the lungs and bronchoalveolar lavage fluid in patients with asthma and models of allergic airway inflammation. Their role in the pathophysiology of asthma and other diseases can be studied using mouse models in which eosinophils are depleted. This review article focuses on two main approaches for depleting eosinophils in vivo, antibody-mediated and genetic models. Specific antibodies and genetic models are reviewed, along with their strengths and weaknesses.

The impact of benzo[a]pyrene on murine allergic airway inflammation via epigenetic remodeling

Simultaneous exposure to both BaP and house dust mites (HDM) has been shown to exacerbate pulmonary inflammation and hyperresponsiveness in a murine asthma model. The mechanistic insight into epigenetic inheritance for this effect, however, remains to be clarified. As such, in this study, we explore the molecular basis for the enhancement of asthma. Female BAL/C mice were intranasally administered HDM (25 µg in 25 μL saline) and/or BaP (10 μg/kg) every other day for 9 weeks. RNA sequencing and DNA methylation assessment were used to explore the underlying mechanism. Following simultaneous exposure to HDM and BaP, mice exhibited pulmonary inflammation and the transcript level of IL4i1b, muc4 and IL22ra2 that were associated with altered DNA methylation, suggesting that there may be an epigenetic basis for BaP-induced asthma exacerbation. Our data suggest that DNA methylation is a major epigenetic modification that accompanies airway remodeling associated with changes in the allergic mice.

Remote regulation of type 2 immunity by intestinal parasites

The intestinal tract is the target organ of most parasitic infections, including those by helminths and protozoa. These parasites elicit prototypical type 2 immune activation in the host's immune system with striking impact on the local tissue microenvironment. Despite local containment of these parasites within the intestinal tract, parasitic infections also mediate immune adaptation in peripheral organs. In this review, we summarize the current knowledge on how such gut-tissue axes influence important immune-mediated resistance and disease tolerance in the context of coinfections, and elaborate on the implications of parasite-regulated gut-lung and gut-brain axes on the development and severity of airway inflammation and central nervous system diseases.

The aggravation of allergic airway inflammation with dibutyl phthalate involved in Nrf2-mediated activation of the mast cells

Dibutyl phthalate (DBP)-an organic pollutant-is ubiquitous in the environment. DBP as an immune adjuvant is related to the development of multiple allergic diseases. However, the current research involving DBP-induced pulmonary toxicity remains poorly understood. Therefore, this research aimed to explore the adverse effect and potential mechanism of DBP exposure on the lungs in rats. In our study, ovalbumin was used to build a rat model of allergic airway inflammation to study any harmful effect of DBP exposure on lung tissues. Rats were treated by intragastric administration of DBP (500 mg kg^-1 or 750 mg kg^-1) and/or subcutaneous injection of SFN (4 mg kg^-1). The results of histopathological analysis, cell count, and myeloperoxidase showed that DBP promoted the inflammatory damage of lungs. In the lung tissues, the detection of terminal deoxynucleotidyl transferase dUNT nick end labeling and oxidative stress indices showed that DBP significantly increased the level of apoptosis and oxidative stress. Western blot analysis indicated that DBP raised the expression level of thymic stromal lymphopoietin and reduced the nuclear expression level of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was further verified by quantitative real-time PCR. Meanwhile, DBP treatment markedly up-regulated the inflammatory cytokines such as IL-4 and IL-13, and rat mast cell protease-2, a marker secreted by mast cells (MCs). Conversely, sulforaphane, a Nrf2 inducer, ameliorated the pulmonary damage induced by DBP in the above. Altogether, our data provides a new insight into the impacts of the activation of MCs on the DBP-induced pulmonary toxicity as well as the safety evaluation of DBP.

Early postnatal allergic airway inflammation induces dystrophic microglia leading to excitatory postsynaptic surplus and autism-like behavior

Microglia play key roles in synaptic pruning, which primarily occurs from the postnatal period to adolescence. Synaptic pruning is essential for normal brain development and its impairment is implicated in neuropsychiatric developmental diseases such as autism spectrum disorders (ASD). Recent epidemiological surveys reported a strong link between ASD and atopic/allergic diseases. However, few studies have experimentally investigated the relationship between allergy and ASD-like manifestations, particularly in the early postnatal period, when allergic disorders occur frequently. Therefore, we aimed to characterize how allergic inflammation in the early postnatal period influences microglia and behavior using mouse models of short- and long-term airway allergy. Male mice were immunized by an intraperitoneal injection of aluminum hydroxide and ovalbumin (OVA) or phosphate-buffered saline (control) on postnatal days (P) 3, 7, and 11, followed by intranasal challenge with OVA or phosphate-buffered saline solution twice a week until P30 or P70. In the hippocampus, Iba-1-positive areas, the size of Iba-1-positive microglial cell bodies, and the ramification index of microglia by Sholl analysis were significantly smaller in the OVA group than in the control group on P30 and P70, although Iba-1-positive microglia numbers did not differ significantly between the two groups. In Iba-1-positive cells, postsynaptic density protein 95 (PSD95)-occupied areas and CD68-occupied areas were significantly decreased on P30 and P70, respectively, in the OVA group compared with the control group. Immunoblotting using hippocampal tissues demonstrated that amounts of PSD95, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor 2, and N-methyl-D-aspartate (NMDA) receptor 2B were significantly increased in the OVA group compared with the control group on P70, and a similar increasing trend for PSD95 was observed on P30. Neurogenesis was not significantly different between the two groups on P30 or P70 by doublecortin immunohistochemistry. The social preference index was significantly lower in the three chamber test and the number of buried marbles was significantly higher in the OVA group than in the control group on P70 but not on P30, whereas locomotion and anxiety were not different between the two groups. Compared with the control group, serum basal corticosterone levels were significantly elevated and hippocampal glucocorticoid receptor (GR) amounts and nuclear GR translocation in microglia, but not in neurons or astrocytes, were significantly decreased in the OVA group on P70 but not on P30. Gene set enrichment analysis of isolated microglia revealed that genes related to immune responses including Toll-like receptor signaling and chemokine signaling pathways, senescence, and glucocorticoid signaling were significantly upregulated in the OVA group compared with the control group on P30 and P70. These findings suggest that early postnatal allergic airway inflammation induces dystrophic microglia that exhibit defective synaptic pruning upon short- and long-term allergen exposure. Furthermore, long-term allergen exposure induced excitatory postsynaptic surplus and ASD-like behavior. Hypothalamo-pituitary-adrenal axis activation and the compensatory downregulation of microglial GR during long-term allergic airway inflammation may also facilitate these changes.

IRAK-M knockout promotes allergic airway inflammation, but not airway hyperresponsiveness, in house dust mite-induced experimental asthma model

Background

IL-1 receptor associated-kinase (IRAK)-M, expressed by airway epithelium and macrophages, was shown to regulate acute and chronic airway inflammation exhibiting a biphasic response in an OVA-based animal model. House dust mite (HDM) is a common real-life aeroallergen highly relevant to asthma pathogenesis. The role of IRAK-M in HDM-induced asthma remains unknown. This study was aimed to investigate the effect of IRAK-M on allergic airway inflammation induced by HDM using IRAK-M knockout (KO) mice and the potential underlying mechanisms.

Methods

IRAK-M KO and wild-type (WT) mice were sensitized and challenged with HDM. The differences in airway inflammation were evaluated 24 hours after the last challenge between the two genotypes of mice using a number of cellular and molecular biological techniques. In vitro mechanistic investigation was also involved.

Results

Lung expression of IRAK-M was significantly upregulated by HDM in the WT mice. Compared with the WT controls, HDM-treated IRAK-M KO mice showed exacerbated infiltration of inflammatory cells, particularly Th2 cells, in the airways and mucus overproduction, higher epithelial mediators IL-25, IL-33 and TSLP and Th2 cytokines in bronchoalveolar lavage (BAL) fluid. Lung IRAK-M KO macrophages expressed higher percentage of costimulatory molecules OX40L and CD 80 and exhibited enhanced antigen uptake. However, IRAK-M KO didn’t impact the airway hyperreactivity (AHR) indirectly induced by HDM.

Conclusions

The findings indicate that IRAK-M protects allergic airway inflammation, not AHR, by modifying activation and antigen uptake of lung macrophages following HDM stimulation. Optimal regulation of IRAK-M might indicate an intriguing therapeutic avenue for allergic airway inflammation.

Epimedin C modulates the balance between Th9 cells and Treg cells through negative regulation of noncanonical NF-κB pathway and MAPKs activation to inhibit airway inflammation in the ovalbumin-induced murine asthma model

Allergic asthma is a common airway inflammatory disease and mainly caused by abnormal immune responses to allergens and viruses. The precise mechanisms of airway inflammation and airway hyper-responsiveness (AHR) are still not completely understood. CD4⁺ helper T cells (Th cells) serve as critical regulators of allergic immunity. The imbalance between T helper 9 (Th9) cells and forkhead box protein 3 (Foxp3)⁺ regulatory T (Treg) cells may contribute to airway inflammation in asthma. Epimedin C, a dominant compound isolated from Herba Epimedii, has shown anti-inflammatory effects and the immunoregulatory activity, such as increase of lymphocyte proliferation. However, the protective role of epimedin C in an experimental model of ovalbumin (OVA)-induced allergic airway inflammation and the underlying mechanism remain unknown. Female BALB/c mice were sensitized by intraperitoneal injection (i.p.) of OVA plus aluminum hydroxide (Alum) and subsequently challenged with an aerosol of 3% OVA in saline. Mice were treated with different concentrations of epimedin C (20 mg/kg/d, 40 mg/kg/d, 80 mg/kg/d) for 4 weeks. Experimental endpoints were evaluated via the analysis of AHR to acetyl-β-methacholine (Mch), differential inflammatory cell counts, concentrations of cytokines interleukin-9 (IL-9), IL-4 and IL-10 in bronchoalveolar lavage fluid (BALF), serum OVA-specific IgE level, as well as airway inflammation, mucus secretion and collagen deposition in mice. Mechanistically, we investigated the percentages of Th9 cells and Treg cells, as well as mRNA levels of IL-9 and transcription factor Foxp3 in lungs. Furthermore, the proteins expression of nuclear factor-κB (NF-κB) family members p105/p50, RelA, p100/p52 and RelB, as well as mitogen-activated protein kinase (MAPK) family members extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 MAPK was detected. Epimedin C dose-dependently attenuated AHR, airway inflammation, mucus hypersecretion and collagen deposition in OVA-induced murine asthma model. The expression levels of IL-9, IL-4 and OVA-specific IgE were significantly decreased while IL-10 was increased by epimedin C. We further confirmed that epimedin C decreased the percentage of lung Th9 cells with lower mRNA expression of IL-9 and increased the percentage of lung Treg cells with higher mRNA expression of Foxp3. In addition, epimedin C dose-dependently decreased the protein levels of p52, RelB, phosphorylation of ERK1/2 and p38 MAPK which are pivotal to the development of Th9 cells and Treg cells. Collectively, epimedin C could inhibit pathophysiological features of asthma by reconstruction of the balance between Th9 cells and Treg cells through regulation of the noncanonical NF-κB p52/RelB pathway and MAPKs activation. These findings suggest epimedin C as a potential remedy for inflammatory airway diseases.

Group 2 ILC Functional Assays in Allergic Airway Inflammation

ILC2s are a rare innate cell population capable of rapidly producing type 2 cytokines prior to the recruitment and expansion of adaptive type 2 T helper cells. As a result, they are implicated in the pathogenesis of many type-2 immune-mediated diseases, including allergic airway inflammation. Here we describe methods for interrogating and analyzing ILC2 biology in the context of allergic airway inflammation, such as flow cytometric analysis of mouse and human ILC2s as well as live imaging of pulmonary ILC2s.

Mas receptor activation attenuates allergic airway inflammation via inhibiting JNK/CCL2-induced macrophage recruitment

BACKGROUND

Defective absorption of acute allergic airway inflammation is involved in the initiation and development of chronic asthma. After allergen exposure, there is a rapid recruitment of macrophages around the airways, which promote acute inflammatory responses. The Ang-(1-7)/Mas receptor axis reportedly plays protective roles in various tissue inflammation and remodeling processes in vivo. However, the exact role of Mas receptor and their underlying mechanisms during the pathology of acute allergic airway inflammation remains unclear.

OBJECTIVE

We investigated the role of Mas receptor in acute allergic asthma and explored its underlying mechanisms in vitro, aiming to find critical molecules and signal pathways.

METHODS

Mas receptor expression was assessed in ovalbumin (OVA)-induced acute asthmatic murine model. Then we estimated the anti-inflammatory role of Mas receptor in vivo and explored expressions of several known inflammatory cytokines as well as phosphorylation levels of MAPK pathways. Mas receptor functions and underlying mechanisms were studied further in the human bronchial epithelial cell line (16HBE).

RESULTS

Mas receptor expression decreased in acute allergic airway inflammation. Multiplex immunofluorescence co-localized Mas receptor and EpCAM, indicated that Mas receptor may function in the bronchial epithelium. Activating Mas receptor through AVE0991 significantly alleviated macrophage infiltration in airway inflammation, accompanied with down-regulation of CCL2 and phosphorylation levels of MAPK pathways. Further studies in 16HBE showed that AVE0991 pre-treatment inhibited LPS-induced or anisomycin-induced CCL2 increase and THP-1 macrophages migration via JNK pathways.

CONCLUSION

Our findings suggested that Mas receptor activation significantly attenuated CCL2 dependent macrophage recruitments in acute allergic airway inflammation through JNK pathways, which indicated that Mas receptor, CCL2 and phospho-JNK could be potential targets against allergic airway inflammation.

Experimental Mouse Models of Asthma and Analysis of CD4 T Cells

Asthma is a highly prevalent lung disease, characterized by airway dysfunction and chronic inflammation. Asthma occurs in both children and adults, but frequently originates in early life. Heterogeneous asthma phenotypes exist, but Th2 cells are key players in a large proportion of cases, while other CD4+ T cell subsets are also implicated in driving and limiting pathology. In this chapter, we describe methods for establishing allergic airway disease to model asthma in adult and neonatal mice, along with protocols for measuring key disease parameters and quantifying and phenotyping CD4+ T cell subtypes.

JNK modulates RAGE/β-catenin signaling and is essential for allergic airway inflammation in asthma

As a leading cause of occupational asthma, toluene diisocyanate (TDI)-induced asthma is an inflammatory disease of the airways with one of the most significant characteristics involving inflammation, in which the receptor of advanced glycation end products (RAGE) plays an extremely important role. However, the mechanism underlying the upregulation of RAGE is still unknown. The aim of the present study was to examine whether JNK mediates β-catenin stabilization via activation of RAGE in asthma. Herein from the results by analyzing the blood from healthy donors and patients with asthma, it was found that the expression of RAGE and p-JNK is highly correlated and elevated concomitantly with the severity of bronchial asthma. Additionally, upon sensitizing and challenging the mice with TDI, we found that RAGE inhibitor (FPS-ZM1) and JNK inhibitor (SP600125) significantly reduced the TDI-induced asthma inflammation in vivo. Furthermore, SP600125 also considerably restored RAGE and p-JNK expression. Besides, the in vitro results from TDI-HSA treatment of 16HBE cells reveal that therapeutic inhibition of JNK reduced TDI driving RAGE expression and β-catenin translocation, while treatment with Anisomycin, a JNK agonist, showed the opposite effect. Moreover, genetic knockdown of RAGE does not contribute to JNK phosphorylation, indicating that JNK functions upstream of RAGE. Collectively, these findings highlight a role for JNK signaling in RAGE/β-catenin regulation and have important therapeutic implications for the treatment of TDI induced asthma.

DZNep attenuates allergic airway inflammation in an ovalbumin-induced murine model

BACKGROUND

Growing evidence shows that enhancer of zeste homolog 2 (EZH2) plays a role in various physiological functions and cancer pathogenesis. However, its contribution to allergic diseases remains controversial. We sought to investigate the role of EZH2 in the pathogenesis of allergic airway inflammation.

METHODS

3-Deazaneplanocin A (DZNep), an indirect inhibitor of EZH2, was administered via intraperitoneal injection in an ovalbumin (OVA)-induced murine model of allergic airway inflammation. The expression of EZH2 in the allergic airway tissues was examined by immunohistochemistry (IHC) and western blot. The inflammatory cell infiltration and the goblet cell hyperplasia in the murine nose and lung were detected by hematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining. Levels of cytokines, including IL-4, IFN-γ, IL-6, and IL-10, were evaluated in the bronchoalveolar lavage fluid (BALF) using Enzyme-linked immune sorbent assay (ELISA).

RESULTS

EZH2 expression was inhibited by DZNep treatment (P < 0.05). The administration of DZNep significantly inhibited the inflammatory cell infiltration (P < 0.0001) and goblet cell hyperplasia (P < 0.001). Moreover, it suppressed the secretion of IL-4 (P < 0.0001) and IL-6 (P < 0.01) in the BALF.

CONCLUSIONS

Our findings demonstrate that DZNep attenuates allergic airway inflammation and could be a new therapeutic option for allergic rhinitis and asthma.

Dibutyl phthalate induces allergic airway inflammation in rats via inhibition of the Nrf2/TSLP/JAK1 pathway

Dibutyl phthalate (DBP), an important plastic contaminant in the environment, is known to cause organ toxicity. Although current research has shown that DBP-induced organ toxicity is associated with oxidative stress, the toxic effect of DBP on the lungs have not been fully elucidated. Therefore, we investigated the potential mechanism by which DBP induces pulmonary toxicity using a model of DBP-induced allergic airway inflammation in rats. The results showed that chronic exposure to DBP induced histopathological damage, inflammation, oxidative stress, apoptosis, and increased the protein levels of thymic stromal lymphopoietin (TSLP) and its downstream protein Janus kinase 1 (JAK1) and signal transducer and activator of transcription 6 (STAT6). Moreover, DBP exposure inhibited nuclear factor-erythroid-2-related factor 2 (Nrf2) and levels of its target genes NAD(P)H quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). Additionally, using in vitro experiments, we found that DBP induced oxidative stress, reduced cell viability, and inhibited the Nrf2/HO-1/NQO1 pathway in mouse alveolar type II epithelial cell line. Overall, these data demonstrate that DBP induces allergic airway inflammation in rats via inhibition of the Nrf2/TSLP/JAK1 pathway.

The anti-asthmatic potential of flavonol kaempferol in an experimental model of allergic airway inflammation

Flavonol kaempferol possesses a broad spectrum of potent pharmacological activities that seem to be effective in the modulation of allergic respiratory diseases. In our study, an experimental animal model of ovalbumin (OVA)-induced allergic airway inflammation in guinea pigs was used to determine the anti-asthmatic potential of kaempferol. The parameters of specific airway resistance (sRaw) and cough reflex response were evaluated in vivo. In vitro, an assessment of tracheal smooth muscle (TSM) contractility and analyses of inflammatory cytokines (IL-4, IL-5, IL-13, GM-CSF, IFN-γ), transforming growth factor (TGF-β1), immune cells count and ciliary beating frequency (CBF) were performed. Both single (6, 20 mg/kg b. w. p. o.) and long-term administered doses of kaempferol (20 mg/kg b. w. p. o., 21 days) suppressed sRaw provoked by histamine in conscious animals. The administration of kaempferol for 21 days attenuated histamine-induced TSM contractility in vitro and ameliorated the progression of chronic airway inflammation by decreasing the levels of IL-5, IL-13, GM-CSF, eosinophil count in bronchoalveolar lavage (BAL) fluid and TGF-β1 protein level in lung tissue. Kaempferol also eliminated the alterations in cough reflex sensitivity invoked by OVA-sensitization, but it did not affect CBF. The results demonstrate that flavonol kaempferol can modulate allergic airway inflammation and associated asthma features (AHR, aberrant stimulation of cough reflex).

Gu-Ben-Fang-Xiao attenuates allergic airway inflammation by inhibiting BAFF-mediated B cell activation

Allergic airway inflammation is one of the major pathological events involved in the development of asthma. The B cell-activating factor (BAFF)-mediated abnormal activation of B cells plays a key role in developing allergic airway inflammation. Here, we investigated the effects of Gu-Ben-Fang-Xiao decoction (GBFXD), a TCM decoction used in the prevention and treatment of allergic asthma, on allergic airway inflammation and BAFF-mediated B cell activation. A mouse model of OVA-Severe respiratory syncytial virus (RSV) induced asthma in the remission stage was administrated with GBFXD by gavage for four weeks, after which, the pulmonary function was evaluated. Pathological changes of the lung were observed by hematoxylin and eosin (HE) staining, and serum levels of IgE, BAFF, and inflammatory factors were detected by ELISA. The expression of BAFF, APRIL, and their related receptors in the lung and spleen was detected by Western blotting and RT-qPCR. Flow cytometry detected B cell subsets in the spleen, PBC, and monocyte subsets in bronchoalveolar lavage fluid (BALF). The results showed that GBFXD improved the lung function, alleviated the inflammatory changes of the lung tissue in OVA-RSV sensitized mice, and reduced levels of IL-6, TNF-α, IL1-β, INOS, IL13 as well as IL-15, IgE, BAFF in the serum of OVA-RAV mice. Additionally, GBFXD significantly reduced the proportion of CD19+CD27+ B cell subpopulation and IgE + B cell subpopulation in the PBC and spleen cells of mice. Furthermore, the expression of BAFF, APRIL, BAFFR, TACI, and AID decreased in the lung and spleen of GBFXD-treated mice, as well as the proportion of CD11b + BAFF + cell subsets in BALF. In conclusion, GBFXD has an inhibitory effect on the secretion of BAFF by pulmonary macrophages and the expression of BAFF-related receptors, thereby reducing B cell activation and the release of IgE. This proposed mechanism contributes to the improvement of allergic airway inflammation and respiratory function in an asthmatic mouse model.

Lysophosphatidic Acid Regulates the Differentiation of Th2 Cells and Its Antagonist Suppresses Allergic Airway Inflammation

BACKGROUND

Lysophosphatidic acid (LPA), a prototypic member of a large family of lysophospholipids, has been recently shown to play a role in immune responses to respiratory diseases. The involvement of LPA in allergic airway inflammation has been reported, but the mechanism remains unclear.

OBJECT

We analyzed the biological activity of LPA in vitro and in vivo and investigated its role in allergic inflammation in mice using an LPA receptor 2 (LPA2) antagonist.

METHODS

We used a murine model with acute allergic inflammation, in which mice are sensitized and challenged with house dust mite, and analyzed airway hyperresponsiveness (AHR), pathological findings, Th2 cytokines, and IL-33 in bronchoalveolar lavage fluid (BALF) and lung homogenates. The effect of LPA on Th2 differentiation and cytokine production was examined in vitro using naive CD4+ T cells isolated from splenocytes. We also investigated in vivo the effects of LPA on intranasal administration in mice.

RESULTS

The LPA2 antagonist suppressed the increase of AHR, the number of total cells, and eosinophils in BALF and lung tissue. It also decreased the production of IL-13 in BALF and IL-33 and CCL2 in the lung. LPA promoted Th2 cell differentiation and IL-13 production by Th2 cells in vitro. Nasal administration of LPA significantly increased the number of total cells and IL-13 in BALF via regulating the production of IL-33 and CCL-2-derived infiltrating macrophages.

CONCLUSION

These findings suggest that LPA plays an important role in allergic airway inflammation and that the blockade of LPA2 might have therapeutic potential for bronchial asthma.

TLR9 mediates the activation of NLRP3 inflammasome and oxidative stress in murine allergic airway inflammation

Toll-like receptor 9 (TLR9) has been reported to mediate airway inflammation, however, the underlying mechanism is poorly understood. In the present study, our objective was to reveal whether TLR9 regulates NLRP3 inflammasome and oxidative stress in murine allergic airway inflammation and Raw264.7 cells. Female wild type(WT)and TLR9^-/-mice on C57BL/6 background were used to induce allergic airway inflammation by challenge of OVA, and Raw264.7 cells with or without TLR9 knockdown by small interfering RNA (siRNA) were stimulated by S.aureus. The results demonstrated that deletion of TLR9 effectively attenuated OVA-induced allergic airway inflammation including inflammatory cells infiltration and goblet cell hyperplasia. Meanwhile, OVA-induced protein expression of NLRP3, caspase-1(p20) and mature IL-1β, as well as secretion of IL-1β and IL-18 in wild type mice (WT) was obviously suppressed by TLR9 deficiency. Concomitantly, the expression of oxidative markers 8-OhDG and nitrotyrosine was increased in OVA-challenged WT mice, while TLR9 deficiency significantly inhibited such increase. Similarly, in the in vitro study, we found that knockdown of TLR9 markedly suppressed S.aureus-induced activation of NLRP3 inflammasome and oxidative stress in Raw264.7 cells. Collectively, our findings indicated that TLR9 may mediate allergic airway inflammation via activating NLRP3 inflammasome and oxidative stress.

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.

Blockade of CD40L inhibits immunogenic maturation of lung dendritic cells: Implications for the role of lung iNKT cells in mouse models of asthma

Some studies have shown that maturation of dendritic cells (DCs) is modulated directly by pathogen components via pattern recognition receptors such as Toll-like receptors, but also by signal like CD40 ligand (CD40 L or CD154) mediated by activated T cells. Several reports indicate that invariant natural killer T (iNKT) cells up-regulate CD40 L upon stimulation and thereby induce activation and maturation of DCs through crosslink with CD40. Our previous findings indicated that iNKT cells promote Th2 cell responses through the induction of immunogenic maturation of lung DCs (LDCs) in the asthmatic murine, but its mechanism remains unclear. Therefore, we investigated the immunomodulatory effects of blockade of CD40 L using anti-CD40 L treatment on Th2 cell responses and immunogenic maturation of LDCs, and further analyzed whether these influences of blockade of CD40 L were related to lung iNKT cells using iNKT cell-deficient mice and the combination treatment of specific iNKT cell activation with anti-CD40 L treatment in murine models of asthma. Our findings showed that blockade of CD40 L using anti-CD40 L treatment attenuated Th2 cell responses in wild-type (WT) mice, but not in CD1d-deficient mice sensitized and challenged with ovalbumin (OVA) or house dust mite (HDM). Meanwhile, blockade of CD40 L down-regulated immunogenic maturation of LDCs in WT mice, but not in CD1d-deficient mice sensitized and challenged with OVA. Additionally, agonistic anti-CD40 treatment reversed the inhibitory effects of anti-CD40 L treatment on Th2 cell responses and LDC activation in an OVA-induced mouse model of asthma. Furthermore, LDCs from asthmatic mice treated with anti-CD40 L could significantly reduce the influence on Th2 cell responses in vivo and in vitro. Finally, α-Galactosylceramide plus anti-CD40 L treatment stimulated lung iNKT cells, but suppressed Th2 cell responses in the asthmatic mice. Taken together, our data raise an evidence that blockade of CD40 L attenuates Th2 cell responses through the inhibition of immunogenic maturation of LDCs, which may be at least partially related to lung iNKT cells in murine models of asthma.

Apolipoprotein E negatively regulates murine allergic airway inflammation via suppressing the activation of NLRP3 inflammasome and oxidative stress

Apolipoprotein E (ApoE) has been reported as a steroid unresponsive gene and functions as a negative regulator of airway hyperreactivity (AHR) and goblet cell hyperplasia in house dust mite (HDM)-challenged mice. However, the role of ApoE in Ovalbumin (OVA)-induced allergic airway inflammation disease and the underlying mechanism are still unknown. In the present study, murine allergic airway inflammation was induced by inhaled OVA for consecutive 7 days in wild type (WT) and ApoE^-/- mice. In the OVA-induced model, the ApoE level in the bronchoalveolar lavage fluid (BALF) and lung tissues was significantly higher than that of control mice. And ApoE deficiency aggravated airway inflammation including leukocytes infiltration, goblet cell hyperplasia and IgE production as compared to those of WT mice after OVA- challenged, suggesting ApoE servers as an endogenous negative regulator of airway inflammation. Furthermore, OVA challenge elevated the activation of NLRP3 inflammasome with higher protein expression of NLRP3, caspase1 and IL-1β, enhanced oxidative stress with higher expression of 8-OHdG, nitrotyrosine and SOD2, increased the expression of mitochondrial fusion/fission markers including Optic Atrophy 1 (OPA1), Mitofusion 2 (Mfn2), dynamin-related protein 1 (DRP1) and Fission 1 (Fis1). However, these OVA-induced changes were augmented in ApoE^-/- mice. Collectively, our results demonstrated that the OVA-induced airway inflammation was aggravated in ApoE^-/- mice, and suggested that the underlying mechanism may be associated with the augmented activation of NLRP3 inflammasome and oxidative stress in ApoE^-/- mice, therefore targeting ApoE pathway might be a novel therapy approach for allergic airway diseases such as asthma.

Inhibition of antigen-specific immune responses by co-application of an indoleamine 2,3-dioxygenase (IDO)-encoding vector requires antigen transgene expression focused on dendritic cells

We have previously shown that particle-mediated epidermal delivery (PMED) of plasmids encoding β-galactosidase (βGal) under control of the fascin-1 promoter (pFascin-βGal) yielded selective production of the protein in skin dendritic cells (DCs), and suppressed Th2 responses in a mouse model of type I allergy by inducing Th1/Tc1 cells. However, intranasal challenge of mice immunized with pFascin-βGal induced airway hyperreactivity (AHR) and neutrophilic inflammation in the lung. The tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO) has been implicated in immune suppression and tolerance induction. Here we investigated the consequences of co-application of an IDO-encoding vector on the modulatory effect of DNA vaccination by PMED using pFascin-βGal in models of eosinophilic allergic and non-eosinophilic intrinsic airway inflammation. IDO-encoding plasmids and pFascin-βGal or pCMV-βGal were co-applied to abdominal skin of BALB/c mice without, before or after sensitization with βGal protein. Immune responses in the lung were analysed after intranasal provocation and airway reactivity was determined by whole body plethysmography. Co-application of pCMV-IDO with pFascin-βGal, but not pCMV-βGal inhibited the Th1/Tc1 immune response after PMED. Moreover, AHR in those mice was attenuated following intranasal challenge. Therapeutic vaccination of βGal-sensitized mice with pFascin-βGal plus pCMV-IDO slightly suppressed airway inflammation and AHR after provocation with βGal protein, while prophylactic vaccination was not effective. Altogether, our data suggest that only the combination of DC-restricted antigen and ubiquitous IDO expression attenuated asthma responses in mice, most probably by forming a tryptophan-depleted and kynurenine-enriched micromilieu known to affect neutrophils and T cells.

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.

Melatonin biosynthesis restored by CpG oligodeoxynucleotides attenuates allergic airway inflammation via regulating NLRP3 inflammasome

AIMS

Both CpG oligodeoxynucleotide (CpG-ODN) and melatonin have been reported to induce Th1 response and contribute to allergic asthma resistance. Here, we aimed to reveal how they confer such effect as well as whether they crosstalk with each other.

MAIN METHODS

Six-week-old Female C57BL/6 mice were challenged by OVA to induce allergic airway inflammation, and were treated with CpG-ODN, CpG-ODN plus Luzindole or melatonin respectively. Bronchoalveolar lavage fluid (BALF) cellularity was classified and counted by Wright's-Giemsa staining. HE and PAS staining were used to analyze airway inflammation. The levels of IL-4, IL-5, IL-13,GM-CSF and IFN-γ, as well as IL-1β and IL-18 were analyzed by ELISA. Protein expressions of ASMT, AANAT, NLRP3, IL-1β and caspase-1 in lung tissue were detected by Western blotting, expression of ASMT and AANAT were further observed by immunohistochemistry.

KEY FINDINGS

We found that CpG-ODN considerably suppressed OVA-induced airway leukocytes infiltration, goblet cell hyperplasia and Th2 cytokines production. Furthermore, the resolution effect of CpG-ODN on OVA-induced allergic airway inflammation occurred in parallel with decreased-activation of NLRP3 inflammasome and increased biosynthesis of melatonin. Blocking the effect of endogenous melatonin by Luzindole abolished the suppressive effect of CpG-ODN on OVA-induced airway inflammation and activation of NLRP3 inflammasome, suggesting such effect was mediated by endogenous melatonin. Moreover, exogenous melatonin pronouncedly ameliorated airway inflammation and decreased the activation of NLRP3 inflammasome.

SIGNIFICANCE

These results proven that CpG-ODN protects against allergic airway inflammation via suppressing the activation of NLRP3 inflammasome, and such effect may be resulted from the restored-production of melatonin.

Exposure to intermittent hypoxia inhibits allergic airway inflammation in a murine model of asthma

PURPOSE

Obesity increases the severity of asthma, and patients with severe asthma are often complicated with obstructive sleep apnea syndrome (OSAS), a concomitant disease of obesity. We investigated whether intermittent hypoxia (IH), which is a physiological feature of OSAS, modifies allergic airway inflammation in a murine model of asthma.

METHODS

Balb/c mice were sensitized by ovalbumin (OVA) intraperitoneally twice (days 1 and 14) and challenged with intranasal OVA three times (days 21, 22, and 23). The mice were exposed to IH either from days 1 to 24 (long exposure) or only from days 21 to 24 (short exposure). The impact of IH exposure to allergic airway inflammation was investigated using these mice models by histologic, morphometric, and molecular techniques. Additionally, the airway responsiveness to acetylcholine was also assessed.

RESULTS

OVA-sensitized and OVA-challenged mice exposed to room air (RA) showed increased total cell and eosinophil numbers in the BALF. The levels of interleukin (IL)-5 and IL-13 in the BALF also increased and goblet cell metaplasia was induced. In contrast, both long and short exposure to IH inhibited the increased total cell and eosinophil numbers. The levels of IL-5 and IL-13 in the BALF also decreased on exposure to IH. Moreover, the goblet cell hyperplasia and airway hyperresponsiveness were significantly reduced in mice exposed to IH compared to those exposed to RA.

CONCLUSIONS

These results suggest that IH may not deteriorate the asthmatic condition in a murine model of asthma.

Anti-inflammatory activity of SintMed65, an N-acylhydrazone derivative, in a mouse model of allergic airway inflammation

Asthma is a chronic, complex and heterogeneous inflammatory illness, characterized by obstruction of the lower airways. About 334 million people worldwide suffer from asthma, and these estimates, as well as the severity of the disease, have increased in the last decades. Glucocorticoids are currently the most widely used drugs in the treatment and control of asthma symptoms, but their prolonged use can cause serious adverse effects. N-acylhydrazone derivatives have been tested in pre-clinical studies in models of inflammatory diseases. Here we tested SintMed65 (N'-[(1E)-3-(4-nitrophenylhydrazono)]-(2E)-propan-2-ylidene-3,5-dinitrobenzohydrazide), a compound belonging to a novel class of immunosuppressive drugs, in a mouse model of allergic airway inflammation. BALB/c mice were sensitized previously and challenged with ovalbumin for five consecutive days and SintMed65 treatment was performed orally 1 h prior to challenge with ovalbumin. Administration of SintMed65, as well as the reference drug dexamethasone, reduced cellularity and the number of eosinophils in the bronchoalveolar fluid (BALF). SintMed65 also reduced the production of Th2 cytokines IL-4, IL-5 and IL-13 in the BALF, and IL-4, IL-10 and CCL8 gene expression in lung, compared to vehicle-treated mice. Importantly, a reduction in the number of leukocytes and in the mucus production in lungs of SintMed65-treated mice was found, compared to the vehicle-treated group. In contrast, IgE production was not significantly altered after treatment with SintMed65. Our results demonstrate that compound SintMed65 possesses anti-inflammatory characteristics, suggesting its therapeutic potential for the treatment of allergic diseases.

Surface PEGylation suppresses pulmonary effects of CuO in allergen-induced lung inflammation

BACKGROUND

Copper oxide (CuO) nanomaterials are used in a wide range of industrial and commercial applications. These materials can be hazardous, especially if they are inhaled. As a result, the pulmonary effects of CuO nanomaterials have been studied in healthy subjects but limited knowledge exists today about their effects on lungs with allergic airway inflammation (AAI). The objective of this study was to investigate how pristine CuO modulates allergic lung inflammation and whether surface modifications can influence its reactivity. CuO and its carboxylated (CuO COOH), methylaminated (CuO NH₃) and PEGylated (CuO PEG) derivatives were administered here on four consecutive days via oropharyngeal aspiration in a mouse model of AAI. Standard genome-wide gene expression profiling as well as conventional histopathological and immunological methods were used to investigate the modulatory effects of the nanomaterials on both healthy and compromised immune system.

RESULTS

Our data demonstrates that although CuO materials did not considerably influence hallmarks of allergic airway inflammation, the materials exacerbated the existing lung inflammation by eliciting dramatic pulmonary neutrophilia. Transcriptomic analysis showed that CuO, CuO COOH and CuO NH₃ commonly enriched neutrophil-related biological processes, especially in healthy mice. In sharp contrast, CuO PEG had a significantly lower potential in triggering changes in lungs of healthy and allergic mice revealing that surface PEGylation suppresses the effects triggered by the pristine material.

CONCLUSIONS

CuO as well as its functionalized forms worsen allergic airway inflammation by causing neutrophilia in the lungs, however, our results also show that surface PEGylation can be a promising approach for inhibiting the effects of pristine CuO. Our study provides information for health and safety assessment of modified CuO materials, and it can be useful in the development of nanomedical applications.

Extract of Helicobacter pylori Ameliorates Parameters of Airway Inflammation and Goblet Cell Hyperplasia following Repeated Allergen Exposure

BACKGROUND

An inverse relation between Helicobacter pylori infection and asthma has been shown in epidemiological studies. Infection with H. pylori, or application of an extract of it before or after sensitization, inhibits allergic airway disease in mice.

OBJECTIVES

The aim of this study was to investigate the effect of an extract of H. pylori on allergic airway disease induced by repeated allergen exposure in mice that were sensitized and challenged prior to extract application.

METHOD

C57BL/6 mice were intranasally (i.n.) sensitized and challenged with house dust mite (HDM). After a minimum of 4 weeks, mice received the H. pylori extract intraperitoneally and were rechallenged i.n. with HDM. Allergen-specific antibodies were measured by ELISA. Cells present in the bronchoalveolar lavage fluid and dendritic cell (DC) subsets in the lung tissue were analyzed by flow cytometry. Tissue inflammation and goblet cell hyperplasia were assessed by histology. Cells of the mediastinal lymph node (mLN) were isolated and in vitro restimulated with HDM or H. pylori extract.

RESULTS

Treatment with H. pylori extract before rechallenge reduced allergen-specific IgE, the DC numbers in the tissue, and goblet cell hyperplasia. Cells isolated from mLN of mice treated with the extract produced significantly more IL-10 and IL-17 after in vitro restimulation with HDM. mLN cells of H. pylori-treated mice that were re-exposed to the H. pylori extract produced significantly more interferon gamma.

CONCLUSIONS

An extract of H. pylori is effective in reducing mucus production and various features of inflammation in HDM rechallenged mice.

Similar immune mechanisms control experimental airway eosinophilia elicited by different allergens and treatment protocols

Background

Mouse models have been extremely valuable in identifying the fundamental mechanisms of airway inflammation that underlie human allergic asthma. Several models are commonly used, employing different methods and routes of sensitisation, and allergens of varying clinical relevance. Although all models elicit similar hallmarks of allergic airway inflammation, including airway eosinophilia, goblet cell hyperplasia and cellular infiltration in lung, it is not established whether they do so by involving the same mechanisms.

Results

We compared the impact of inactivation of various innate or adaptive immune genes, as well as sex, in different models of allergic airway inflammation in mice of C57BL/6 background. Chicken ovalbumin (OVA) and house dust mite (HDM) were used as allergens in settings of single or multiple intranasal (i.n.) challenges, after sensitisation in adjuvant or in adjuvant-free conditions. Eosinophil numbers in the broncho-alveolar lavage and lung histopathology were assessed in each model. We found that Major Histocompatibility Complex Class II (MHCII) deficiency and lack of conventional CD4+ T cells had the most profound effect, essentially ablating airway eosinophilia and goblet cell hyperplasia in all models. In contrast, Thymic stromal lymphopoietin receptor (TSLPR) deficiency greatly reduced eosinophilia but had a variable effect on goblet cells. CD1d deficiency and lack of Natural Killer T (NKT) cells moderately impaired inflammation in OVA models but not HDM, whereas sex affected the response to HDM but not OVA. Lastly, defective Toll-like receptor (TLR)4 expression had only a relatively modest overall impact on inflammation.

Conclusion

All the models studied were comparably dependent on adaptive CD4+ T cell responses and TSLP. In contrast, sex, NKT cells and TLR4 appeared to play subtler and more variable roles that were dependent on the type of allergen and mode of immunization and challenge. These results are consistent with clinical data suggesting a key role of CD4+ T cells and TSLP in patients with allergic asthma.

Electronic supplementary material

The online version of this article (10.1186/s12865-019-0295-y) contains supplementary material, which is available to authorized users.

Transmaternal Helicobacter pylori exposure reduces allergic airway inflammation in offspring through regulatory T cells

BACKGROUND

Transmaternal exposure to tobacco, microbes, nutrients, and other environmental factors shapes the fetal immune system through epigenetic processes. The gastric microbe Helicobacter pylori represents an ancestral constituent of the human microbiota that causes gastric disorders on the one hand and is inversely associated with allergies and chronic inflammatory conditions on the other.

OBJECTIVE

Here we investigate the consequences of transmaternal exposure to H pylori in utero and/or during lactation for susceptibility to viral and bacterial infection, predisposition to allergic airway inflammation, and development of immune cell populations in the lungs and lymphoid organs.

METHODS

We use experimental models of house dust mite- or ovalbumin-induced airway inflammation and influenza A virus or Citrobacter rodentium infection along with metagenomics analyses, multicolor flow cytometry, and bisulfite pyrosequencing, to study the effects of H pylori on allergy severity and immunologic and microbiome correlates thereof.

RESULTS

Perinatal exposure to H pylori extract or its immunomodulator vacuolating cytotoxin confers robust protective effects against allergic airway inflammation not only in first- but also second-generation offspring but does not increase susceptibility to viral or bacterial infection. Immune correlates of allergy protection include skewing of regulatory over effector T cells, expansion of regulatory T-cell subsets expressing CXCR3 or retinoic acid-related orphan receptor γt, and demethylation of the forkhead box P3 (FOXP3) locus. The composition and diversity of the gastrointestinal microbiota is measurably affected by perinatal H pylori exposure.

CONCLUSION

We conclude that exposure to H pylori has consequences not only for the carrier but also for subsequent generations that can be exploited for interventional purposes.

TNF-TNFR2 Signaling Inhibits Th2 and Th17 Polarization and Alleviates Allergic Airway Inflammation

BACKGROUND

TNF-TNFR2 signaling has been indicated to be involved in CD4+ T lymphocyte differentiation. However, its role in allergic airway inflammation is not well understood.

OBJECTIVES

The aim of this study was to investigate the role of TNF-TNFR2 signaling in allergic airway inflammation.

METHODS AND RESULTS

In this study, we used an allergen-induced asthma model to show that TNF-TNFR2 signaling alleviated allergic airway inflammation by reducing the airway infiltration of eosinophils and neutrophils. Activated TNF-TNFR2 signaling decreased the expression of Th2 and Th17 cytokines in serum and bronchoalveolar lavage fluid. Furthermore, TNF-TNFR2 signaling inhibited Th2 and Th17 polarization but promoted Th1 and CD4+CD25+ T cell differentiation in vivo.

CONCLUSIONS

Our study indicates that TNF-TNFR2 signaling alleviates allergic airway inflammation through inhibition of Th2 and Th17 cell differentiation.

Cyanidin-3-O-β-glucoside attenuates allergic airway inflammation by modulating the IL-4Rα-STAT6 signaling pathway in a murine asthma model

Cyanidin-3-O-β-glucoside (Cy-3-g), a typical and abundant monomer of anthocyanins, exhibits a variety of biological activities, such as anti-atherosclerosis, anti-obesity, and anticancer effects. However, to date little is known about its effects on asthma. This study aimed to investigate the efficacy of dietary Cy-3-g on allergic asthma in an animal model. BALB/c mice were sensitized and challenged with ovalbumin (OVA) to induce allergic asthma. The pathological changes of the lung tissues, type 2 helper (Th2)-associated cytokine production in bronchoalveolar lavage fluid (BALF), and the interleukin 4 receptor alpha (IL-4Rα)-signal transducer and activator of transcription 6 (STAT6) signaling pathway activities were assessed. We found that Cy-3-g significantly inhibited OVA-induced inflammatory cell infiltration and mucus hyper-production in lung tissues, reduced the production of interleukin 4 (IL-4), interleukin 5 (IL-5) and interleukin 13 (IL-13) in BALF. Furthermore, Cy-3-g effectively suppressed OVA-induced up-regulation of the IL-4Rα-STAT6 signaling pathway activity of the lung tissues. These results demonstrated that dietary Cy-3-g could attenuate allergic airway inflammation in a murine asthma model, and Cy-3-g might be used as an agent for asthma prevention and/or treatment in the future.

The effect of erdosteine on airway defence mechanisms and inflammatory cytokines in the settings of allergic inflammation

INTRODUCTION

Mucoactive agent, erdosteine, besides mucolytic activity, is characterized by many other pharmacodynamic properties which could be beneficial in the management of inflammatory conditions.

BACKGROUND

Using guinea pig experimental model of allergic inflammation, we evaluated the ability of erdosteine to modulate airway defence mechanisms and inflammation after 10 days (10 mg/kg/day) administration.

METHODS

In vivo changes in specific airway resistance and amplitude of tracheal contraction were estimated to evaluate the bronchodilatory effect. The sensitivity of chemically induced cough reflex was estimated via in vivo method. The ciliary beat frequency assessed on brushed tracheal cells was used as an indicator of the mucociliary clearance rate. The concentrations of the inflammatory cytokines IL-4, IL-5, IL-13 and IL-10 were measured in BALF using multiplex detecting method.

RESULTS

Our data show that 10 days erdosteine administration resulted in bronchodilation and stimulation of ciliary beat frequency. Erdosteine did not affect the parameters of chemically induced cough reflex. Erdosteine demonstrated the modest decline in inflammatory cytokines IL-5, IL-13 and an increase in the concentration of IL-10, which is a potent regulator of inflammatory responses and plays a critical role in controlling allergic airway inflammation.

CONCLUSION

In summary, we can state, that erdosteine is multi-action drug and it seems to have many beneficial and complementary effect in the management of chronic inflammatory airway diseases complicated by viscous mucus.

Role of estrogen receptors α and β in the development of allergic airway inflammation in mice: A possible involvement of interleukin 33 and eosinophils

Recent studies have shown that the estrogen receptor α (ERα), but not ERβ, is involved in the proinflammatory and propruritic responses in cutaneous allergy. In addition, results from our recent study showed that while oral administration of the rather ERβ-selective agonist bisphenol A exacerbated the respiratory allergic inflammation, the potential inflammatory reaction in the skin was decreased after administration of bisphenol A. This study aimed to elucidate whether ERα and ERβ are involved in the progression of an allergic airway inflammation. We performed an in vivo experiment using an animal model of allergic airway inflammation using male BALB/c mice to confirm an increase in the proinflammatory response induced by propylpyrazoletriol (PPT), an ERα agonist, and diarylpropionitrile (DPN), an ERβ agonist. Oral administration of PPT or DPN showed a significant increase in the inflammation of the lung and infiltration of eosinophils. While the expression of Th2 cytokines such as interleukin 4 (IL-4) and IL-13 was not affected by exposure to PPT or DPN, administration of these agonists significantly increased the expression of IL-33. The mechanism underlying the development of such allergic inflammatory responses was determined by an in vitro study using the human bronchial epithelial cell line (BEAS-2B) and the human eosinophilic leukemia cell line (EoL-1). Activated cells were exposed to PPT or DPN for 24 h, and the cytokine levels were measured. The IL-33 levels in BEAS-2B cells increased significantly after exposure to PPT or DPN. In addition, pretreatment with PPT or DPN increased the expression of IL-8 in activated EoL-1 cells. Our findings indicate that ERα and ERβ are involved in the proinflammatory response in respiratory allergy, and their effects may be mediated by an increase in the expression of IL-33 and infiltration of eosinophils.

Anti-inflammatory role of CD11b+Ly6G+ neutrophilic cells in allergic airway inflammation in mice

Asthma is a chronic inflammatory disease driven by overactivation of T helper cell type 2 (Th2) responses. In the present study, we investigated the functional relevance of CD11b⁺Ly6G⁺ neutrophilic cells in allergic airway inflammation in vivo. Allergic airway inflammation in mice was induced by house dust mite (HDM) or ovalbumin (OVA) sensitization and challenge. CD11b⁺Ly6G⁺ neutrophilic cells and T cell phenotypes were quantified by flow cytometry. To assess the functional in vivo relevance, CD11b⁺Ly6G⁺ neutrophilic cells were adoptively transferred intravenously or intratracheally and consequences on airway inflammation were studied. Adoptively transferred CD11b⁺Ly6G⁺ neutrophilic cells attenuated Th2 and Th17 responses and airway inflammation in vivo. Collectively, our results demonstrate that CD11b⁺Ly6G⁺ neutrophilic cells suppress airway inflammation in allergic mice in vivo. Adoptive cellular transfer of suppressive neutrophilic cells may represent an attractive therapeutic strategy for allergic airway inflammation.

Exhaled Nitric Oxide: An Update

Fractional concentration of exhaled nitric oxide (FENO) is a biomarker used to identify allergic airway inflammation. Because it is noninvasive and easy to obtain, its utility has been studied in the diagnosis and management of several respiratory diseases. Much of the research has been done in asthma, and many studies support the use of FENO in aiding diagnosing asthma, predicting steroid responsiveness, and preventing exacerbations by guiding medication dosage and assessing adherence.

Ambient particulate matter enhances the pulmonary allergic immune response to house dust mite in a BALB/c mouse model by augmenting Th2- and Th17-immune responses

Ambient particulate matter (PM) exacerbates airway inflammation and hyper-reactivity in asthmatic patients. Studies show that PM has adjuvant-like properties that enhance the allergic inflammatory response; however, the mechanisms through which PM enhances these processes remain elusive. The objective of the study was to examine how ambient PM enhances the allergic immune response. Eight-week-old BALB/c mice were sensitized with house dust mite (HDM) or HDM and ambient particulate matter (PM, 2.5 μm; Sacramento, CA) to assess how PM modulates the development of adaptive immune responses against allergens. Both groups were challenged with HDM only. Bronchoalveolar lavage (BAL) was analyzed for extent of airway inflammation. Lung tissue was used for histological analysis, mucosubstance quantification, and heme oxygenase-1 (HO-1) localization/quantification. Gene expression was analyzed in whole lung to characterize immune markers of inflammation: cytokines, chemokines, antioxidant enzymes, and transcription factors. Cytokine and chemokine protein levels were quantified in whole lung to confirm gene expression patterns. Compared to HDM-only sensitization, exposure to PM during HDM sensitization led to significant immune cell recruitment into the airway subepithelium, IgE gene expression, mucosubstance production, and Th2-associated cytokine expression. HO-1 levels were not significantly different between the treatment groups. Gene expression profiles suggest that polycyclic aromatic hydrocarbon (PAH) content in PM activated the aryl hydrocarbon receptor (AhR) and enhanced Th17-responses in the mice that received HDM and PM compared to mice that received HDM-only. The findings suggest that PM enhances allergic sensitization via enhancement of Th2-mediated inflammation and that AhR activation by PAHs in PM promotes Th17-immune responses.

Nanoformulated ABT-199 to effectively target Bcl-2 at mitochondrial membrane alleviates airway inflammation by inducing apoptosis

Elimination of airway inflammatory cells is essential for asthma control. As Bcl-2 protein is highly expressed on the mitochondrial outer membrane in inflammatory cells, we chose a Bcl-2 inhibitor, ABT-199, which can inhibit airway inflammation and airway hyperresponsiveness by inducing inflammatory cell apoptosis. Herein, we synthesized a pH-sensitive nanoformulated Bcl-2 inhibitor (Nf-ABT-199) that could specifically deliver ABT-199 to the mitochondria of bronchial inflammatory cells. The proof-of-concept study of an inflammatory cell mitochondria-targeted therapy using Nf-ABT-199 was validated in a mouse model of allergic asthma. Nf-ABT-199 was proven to significantly alleviate airway inflammation by effectively inducing eosinophil apoptosis and inhibiting both inflammatory cell infiltration and mucus hypersecretion. In addition, the nanocarrier or Nf-ABT-199 showed no obvious influence on cell viability, airway epithelial barrier and liver function, implying excellent biocompatibility and with non-toxic effect. The nanoformulated Bcl-2 inhibitor Nf-ABT-199 accumulates in the mitochondria of inflammatory cells and efficiently alleviates allergic asthma.