Combined forced oscillation and forced expiration measurements in mice for the assessment of airway hyperresponsiveness

Adam19 Deficiency Impacts Pulmonary Function: Human GWAS Follow-up in a Mouse Knockout Model

PURPOSE

Over 550 loci have been associated with human pulmonary function in genome-wide association studies (GWAS); however, the causal role of most remains uncertain. Single nucleotide polymorphisms in a disintegrin and metalloprotease domain 19 (ADAM19) are consistently related to pulmonary function in GWAS. Thus, we used a mouse model to investigate the causal link between Adam19 and pulmonary function.

METHODS

We created an Adam19 knockout (KO) mouse model and validated the gene targeting using RNA-Seq and RT-qPCR. Mouse body composition was assessed using dual-energy X-ray absorptiometry. Mouse lung function was measured using flexiVent.

RESULTS

Contrary to prior publications, the KO was not neonatal lethal. KO mice had lower body weight and shorter tibial length than wild-type (WT) mice. Their body composition revealed lower soft weight, fat weight, and bone mineral content. Adam19 KO had decreased baseline respiratory system elastance, minute work of breathing, tissue damping, tissue elastance, and forced expiratory flow at 50% forced vital capacity but higher FEV0.1 and FVC. Adam19 KO had attenuated tissue damping and tissue elastance in response to methacholine following LPS exposure. Adam19 KO also exhibited attenuated neutrophil extravasation into the airway after LPS administration compared to WT. RNA-Seq analysis of KO and WT lungs identified several differentially expressed genes (Cd300lg, Kpna2, and Pttg1) implicated in lung biology and pathogenesis. Gene set enrichment analysis identified negative enrichment for TNF pathways.

CONCLUSION

Our murine findings support a causal role of ADAM19, implicated in human GWAS, in regulating pulmonary function.

Chemical respiratory sensitization-Current status of mechanistic understanding, knowledge gaps and possible identification methods of sensitizers

Respiratory sensitization is a complex immunological process eventually leading to hypersensitivity following re-exposure to the chemical. A frequent consequence is occupational asthma, which may occur after long latency periods. Although chemical-induced respiratory hypersensitivity has been known for decades, there are currently no comprehensive and validated approaches available for the prospective identification of chemicals that induce respiratory sensitization, while the expectations of new approach methodologies (NAMs) are high. A great hope is that due to a better understanding of the molecular key events, new methods can be developed now. However, this is a big challenge due to the different chemical classes to which respiratory sensitizers belong, as well as because of the complexity of the response and the late manifestation of symptoms. In this review article, the current information on respiratory sensitization related processes is summarized by introducing it in the available adverse outcome pathway (AOP) concept. Potentially useful models for prediction are discussed. Knowledge gaps and gaps of regulatory concern are identified.

Immunological Effects of Diesel Particles in a Murine Model of Healthy Mice

Introduction: Exposure to environmental pollutants such as diesel exhaust particles (DEP) increases the risk of respiratory disease exacerbation. However, the possible effects of these particles on the general population remain poorly understood. The present study aimed to assess the immunomodulatory and inflammatory effects of the inhalation of DEP in a model of healthy mice undergoing short-, mid- and long-term exposure. Materials and Methods: BALB/c ByJ mice were randomly divided into five experimental groups. The control group received three intranasal instillations of saline over 8 days while the other four groups received intranasal instillations of 150 µg of DEP 3 days per week for 8, 17, 26, and 53 days. Lung function assessment and flow cytometry were performed. Results: In lung tissue, intranasal exposure to DEP decreased total monocytes (p < 0.015 in all groups). At 26 days, a reduction in inflammatory monocytes and an increase in resident monocytes were observed, p = 0.001 and 0.0001, respectively. Eosinophils and neutrophils decreased at 26 days (p = 0.017 and p = 0.041, respectively). The intranasal challenges of DEP increased the total population of dendritic cells (DC) at 26 and 53 days (p = 0.017 and p = 0.022, respectively) and decreased the total and alveolar populations of macrophages (p < 0.003 for all groups compared to control), while interstitial macrophage populations increased over the time period (p = 0.0001 for all groups compared to control). Conclusions: Continuous DEP exposure triggers immune mechanisms that predispose healthy individuals to a pro-inflammatory and hyper-reactive microenvironment. This mouse model provides evidence of the capacity of DEP to increase DC, interstitial macrophages, and resident monocytes.

Adam19 Deficiency Impacts Pulmonary Function: Human GWAS Follow-up in Mouse

Purpose

Over 550 loci have been associated with human pulmonary function in genome-wide association studies (GWAS); however, the causal role of most remains uncertain. Single nucleotide polymorphisms in a disintegrin and metalloprotease domain 19 (ADAM19) are consistently related to pulmonary function in GWAS. Thus, we used a mouse model to investigate the causal link between Adam19 and pulmonary function.

Methods

We created an Adam19 knockout (KO) mouse model and validated the gene targeting using RNA-Seq and RT-qPCR. Contrary to prior publications, the KO was not neonatal lethal. Thus, we phenotyped the Adam19 KO.

Results

KO mice had lower body weight and shorter tibial length than wild type (WT). Dual-energy X-ray Absorptiometry indicated lower soft weight, fat weight, and bone mineral content in KO mice. In lung function analyses using flexiVent, compared to WT, Adam19 KO had decreased baseline respiratory system elastance, minute work of breathing, tissue damping, tissue elastance, and forced expiratory flow at 50% forced vital capacity but higher FEV0.1 and FVC. Adam19 KO had attenuated tissue damping and tissue elastance in response to methacholine following LPS exposure. Adam19 KO also exhibited attenuated neutrophil extravasation into the airway after LPS administration compared to WT. RNA-Seq analysis of KO and WT lungs identified several differentially expressed genes (Cd300lg, Kpna2, and Pttg1) implicated in lung biology and pathogenesis. Gene set enrichment analysis identified negative enrichment for TNF pathways.

Conclusion

Our murine findings support a causal role of ADAM19, implicated in human GWAS, in regulating pulmonary function.

Antenatal Endotoxin Induces Dysanapsis in Experimental Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is characterized by impaired lung development with sustained functional abnormalities due to alterations of airways and the distal lung. Although clinical studies have shown striking associations between antenatal stress and BPD, little is known about the underlying pathogenetic mechanisms. Whether dysanapsis, the concept of discordant growth of the airways and parenchyma, contributes to late respiratory disease as a result of antenatal stress is unknown. We hypothesized that antenatal endotoxin (ETX) impairs juvenile lung function as a result of altered central airway and distal lung structure, suggesting the presence of dysanapsis in this preclinical BPD model. Fetal rats were exposed to intraamniotic ETX (10 μg) or saline solution (control) 2 days before term. We performed extensive structural and functional evaluation of the proximal airways and distal lung in 2-week-old rats. Distal lung structure was quantified by stereology. Conducting airway diameters were measured using micro-computed tomography. Lung function was assessed during invasive ventilation to quantify baseline mechanics, response to methacholine challenge, and spirometry. ETX-exposed pups exhibited distal lung simplification, decreased alveolar surface area, and decreased parenchyma-airway attachments. ETX-exposed pups exhibited decreased tracheal and second- and third-generation airway diameters. ETX increased respiratory system resistance and decreased lung compliance at baseline. Only Newtonian resistance, specific to large airways, exhibited increased methacholine reactivity in ETX-exposed pups compared with controls. ETX-exposed pups had a decreased ratio of FEV in 0.1 second to FVC and a normal FEV in 0.1 second, paralleling the clinical definition of dysanapsis. Antenatal ETX causes abnormalities of the central airways and distal lung growth, suggesting that dysanapsis contributes to abnormal lung function in juvenile rats.

Particulate matter-mediated oxidative stress induces airway inflammation and pulmonary dysfunction through TXNIP/NF-κB and modulation of the SIRT1-mediated p53 and TGF-β/Smad3 pathways in mice

Exposure to particulate matter is currently recognized as a serious aggravating factor of respiratory diseases. In this study, we investigated the effects of particulate matter (PM) on the respiratory system in BALB/c mice and NCI-H292 cells. PM (0, 2.5, 5 and 20 mg/kg) was administered to mice by intra-tracheal instillation for 7 days. After a 7 day-repeated treatment of PM, we evaluated inflammatory cytokines/cell counts in bronchoalveolar lavage fluid (BALF) and conducted pulmonary histology and functional test. We also investigated the role of TXNIP/NF-κB and SIRT1-mediated p53 and TGF-β/Smad3 pathways in PM-induced airway inflammation and pulmonary dysfunction. PM caused a significant increase in pro-inflammatory cytokines, inflammatory cell counts in bronchoalveolar lavage fluid. PM-mediated oxidative stress down-regulated thioredoxin-1 and up-regulated thioredoxin-interacting protein and activation of nuclear factor-kappa B in the lung tissue and PM-treated NCI-H292 cells. PM suppressed sirtuin1 protein levels and increased p53 acetylation in PM-exposed mice and PM-treated NCI-H292 cells. In addition, PM caused inflammatory cell infiltration and the thickening of alveolar walls by exacerbating the inflammatory response in the lung tissue. PM increased levels of transforming growth factor-β, phosphorylation of Smad3 and activation of α-smooth muscle actin, and collagen type1A2 in PM-exposed mice and PM-treated NCI-H292 cells. In pulmonary function tests, PM exposure impaired pulmonary function resembling pulmonary fibrosis, characterized by increased resistance and elastance of the respiratory system, and resistance, elastance, and damping of lung tissues, whereas decreased compliance of the respiratory system, forced expired volume and forced vital capacity. Overall, PM-mediated oxidative stress caused airway inflammation and pulmonary dysfunction with pulmonary fibrosis via TXNIP pathway/NF-κB activation and modulation of the SIRT1-mediated TGF-β/Smad3 pathways. The results of this study can provide fundamental data on the potential adverse effects and underlying mechanism of pulmonary fibrosis caused by PM exposure as a public health concern. Due to the potential toxicity of PM, people with respiratory disease must be careful with PM exposure.

Harnessing the translational power of bleomycin model: new insights to guide drug discovery for idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, age-related interstitial lung disease (ILD) with limited therapeutic options. Despite the wide variety of different in vivo models for IPF, these preclinical models have shown limitations that may significantly impair their translational potential. Among the most relevant limitations are the methodologies used to assess the efficacy of anti-fibrotic treatments, that are not the ones used in humans. In this scenario, the goal of the work presented in this paper is to provide translational relevance to the bleomycin (BLM)-induced pulmonary fibrosis mouse model, introducing and validating novel readouts to evaluate the efficacy of treatments for IPF. Methods: The BLM model was optimized by introducing the use of functional assessments such as the Forced Vital Capacity (FVC) and the Diffusion Factor for Carbon Monoxide (DFCO), that are respectively the primary and secondary endpoints in clinical trials for IPF, comparing them to more common readouts such as lung histology, improved by the application of Artificial Intelligence (AI) to detect and quantify fibrotic tissue deposition, and metalloproitenase-7 (MMP-7), a clinical prognostic biomarker. Results: Lung function measurement and DFCO changes well correlated with Ashcroft score, the current gold-standard for the assessment of pulmonary fibrosis in mice. The relevance and robustness of these novel readouts in the BLM model was confirmed by the results obtained testing Nintedanib and Pirfenidone, the only drugs approved for the treatment of IPF patients: in fact, both drugs administered therapeutically, significantly affected the changes in these parameters induced by BLM treatment, with results that closely reflected the efficacy observed in the clinic. Changes in biomarkers such as MMP-7 were also evaluated, and well correlated with the modifications of FVC and DFCO. Conclusion: Novel functional readouts such as FVC and DFCO can be efficiently used to assess pathology progression in the BLM-induced pulmonary fibrosis mouse model as well as compound efficacy, substantially improving its translational and predictivity potential.

Small-Molecule Activation of Protein Phosphatase 2A Counters Bleomycin-Induced Fibrosis in Mice

The activity of protein phosphatase 2A (PP2A), a serine-threonine phosphatase, is reduced in the lung fibroblasts of idiopathic pulmonary fibrosis (IPF) patients. The objective of this study was to determine whether the reactivation of PP2A could reduce fibrosis and preserve the pulmonary function in a bleomycin (BLM) mouse model. Here, we present a new class of direct small-molecule PP2A activators, diarylmethyl-pyran-sulfonamide, exemplified by ATUX-1215. ATUX-1215 has improved metabolic stability and bioavailability compared to our previously described PP2A activators. Primary human lung fibroblasts were exposed to ATUX-1215 and an older generation PP2A activator in combination with TGFβ. ATUX-1215 treatment enhanced the PP2A activity, reduced the phosphorylation of ERK and JNK, and reduced the TGFβ-induced expression of ACTA2, FN1, COL1A1, and COL3A1. C57BL/6J mice were administered 5 mg/kg ATUX-1215 daily following intratracheal instillation of BLM. Three weeks later, forced oscillation and expiratory measurements were performed using the Scireq Flexivent System. ATUX-1215 prevented BLM-induced lung physiology changes, including the preservation of normal PV loop, compliance, tissue elastance, and forced vital capacity. PP2A activity was enhanced with ATUX-1215 and reduced collagen deposition within the lungs. ATUX-1215 also prevented the BLM induction of Acta2, Ccn2, and Fn1 gene expression. Treatment with ATUX-1215 reduced the phosphorylation of ERK, p38, JNK, and Akt and the secretion of IL-12p70, GM-CSF, and IL1α in BLM-treated animals. Delayed treatment with ATUX-1215 was also observed to slow the progression of lung fibrosis. In conclusion, our study indicates that the decrease in PP2A activity, which occurs in fibroblasts from the lungs of IPF subjects, could be restored with ATUX-1215 administration as an antifibrotic agent.

Evaluating Novel Protein Phosphatase 2A Activators as Therapeutics for Emphysema

The activity of PP2A (protein phosphatase 2A), a serine-threonine phosphatase, is reduced by chronic cigarette smoke (SM) exposure and α-1 antitrypsin (AAT) deficiency, and chemical activation of PP2A reduces the loss of lung function in SM-exposed mice. However, the previously studied PP2A-activator tricyclic sulfonamide compound DBK-1154 has low stability to oxidative metabolism, resulting in fast clearance and low systemic exposure. Here we compare the utility of a new more stable PP2A activator, ATUX-792, versus DBK-1154 for the treatment of SM-induced emphysema. ATUX-792 was also tested in human bronchial epithelial cells and a mouse model of AAT deficiency, Serpina1a-e-knockout mice. Human bronchial epithelial cells were treated with ATUX-792 or DBK-1154, and cell viability, PP2A activity, and MAP (mitogen-activated protein) kinase phosphorylation status were examined. Wild-type mice received vehicle, DBK-1154, or ATUX-792 orally in the last 2 months of 4 months of SM exposure, and 8-month-old Serpina1a-e-knockout mice received ATUX-792 daily for 4 months. Forced oscillation and expiratory measurements and histology analysis were performed. Treatment with ATUX-792 or DBK-1154 resulted in PP2A activation, reduced MAP kinase phosphorylation, immune cell infiltration, reduced airspace enlargements, and preserved lung function. Using protein arrays and multiplex assays, PP2A activation was observed to reduce AAT-deficient and SM-induced release of CXCL5, CCL17, and CXCL16 into the airways, which coincided with reduced neutrophil lung infiltration. Our study indicates that suppression of the PP2A activity in two models of emphysema could be restored by next-generation PP2A activators to impact lung function.

Type 1 diabetes contributes to combined pulmonary fibrosis and emphysema in male alpha 1 antitrypsin deficient mice

Type 1 diabetes (T1D) is a metabolic disease characterized by hyperglycemia and can affect multiple organs, leading to life-threatening complications. Increased prevalence of pulmonary disease is observed in T1D patients, and diabetes is a leading cause of comorbidity in several lung pathologies. A deficiency of alpha-1 antitrypsin (AAT) can lead to the development of emphysema. Decreased AAT plasma concentrations and anti-protease activity are documented in T1D patients. The objective of this study was to determine whether T1D exacerbates the progression of lung damage in AAT deficiency. First, pulmonary function testing (PFT) and histopathological changes in the lungs of C57BL/6J streptozotocin (STZ)-induced T1D mice were investigated 3 and 6 months after the onset of hyperglycemia. PFT demonstrated a restrictive pulmonary pattern in the lungs of STZ-injected mice, along with upregulation of mRNA expression of pro-fibrotic markers Acta2, Ccn2, and Fn1. Increased collagen deposition was observed 6 months after the onset of hyperglycemia. To study the effect of T1D on the progression of lung damage in AAT deficiency background, C57BL/6J AAT knockout (KO) mice were used. Control and STZ-challenged AAT KO mice did not show significant changes in lung function 3 months after the onset of hyperglycemia. However, histological examination of the lung demonstrated increased collagen accumulation and alveolar space enlargement in STZ-induced AAT KO mice. AAT pretreatment on TGF-β-stimulated primary lung fibroblasts reduced mRNA expression of pro-fibrotic markers ACTA2, CCN2, and FN1. Induction of T1D in AAT deficiency leads to a combined pulmonary fibrosis and emphysema (CPFE) phenotype in male mice.

Pulmonary pathogenesis in a murine model of inhaled arsenical exposure

Arsenic trioxide (ATO), an inorganic arsenical, is a toxic environmental contaminant. It is also a widely used chemical with industrial and medicinal uses. Significant public health risk exists from its intentional or accidental exposure. The pulmonary pathology of acute high dose exposure is not well defined. We developed and characterized a murine model of a single inhaled exposure to ATO, which was evaluated 24 h post-exposure. ATO caused hypoxemia as demonstrated by arterial blood-gas measurements. ATO administration caused disruption of alveolar-capillary membrane as shown by increase in total protein and IgM in the bronchoalveolar lavage fluid (BALF) supernatant and an onset of pulmonary edema. BALF of ATO-exposed mice had increased HMGB1, a damage-associated molecular pattern (DAMP) molecule, and differential cell counts revealed increased neutrophils. BALF supernatant also showed an increase in protein levels of eotaxin/CCL-11 and MCP-3/CCL-7 and a reduction in IL-10, IL-19, IFN-γ, and IL-2. In the lung of ATO-exposed mice, increased protein levels of G-CSF, CXCL-5, and CCL-11 were noted. Increased mRNA levels of TNF-a, and CCL2 in ATO-challenged lungs further supported an inflammatory pathogenesis. Neutrophils were increased in the blood of ATO-exposed animals. Pulmonary function was also evaluated using flexiVent. Consistent with an acute lung injury phenotype, respiratory and lung elastance showed significant increase in ATO-exposed mice. PV loops showed a downward shift and a decrease in inspiratory capacity in the ATO mice. Flow-volume curves showed a decrease in FEV0.1 and FEF50. These results demonstrate that inhaled ATO leads to pulmonary damage and characteristic dysfunctions resembling ARDS in humans.

Lung function measurements in preclinical research: What has been done and where is it headed?

Due to the close interaction of lung morphology and functions, repeatable measurements of pulmonary function during longitudinal studies on lung pathophysiology and treatment efficacy have been a great area of interest for lung researchers. Spirometry, as a simple and quick procedure that depends on the maximal inspiration of the patient, is the most common lung function test in clinics that measures lung volumes against time. Similarly, in the preclinical area, plethysmography techniques offer lung functional parameters related to lung volumes. In the past few decades, many innovative techniques have been introduced for in vivo lung function measurements, while each one of these techniques has their own advantages and disadvantages. Before each experiment, depending on the sensitivity of the required pulmonary functional parameters, it should be decided whether an invasive or non-invasive approach is desired. On one hand, invasive techniques offer sensitive and specific readouts related to lung mechanics in anesthetized and tracheotomized animals at endpoints. On the other hand, non-invasive techniques allow repeatable lung function measurements in conscious, free-breathing animals with readouts related to the lung volumes. The biggest disadvantage of these standard techniques for lung function measurements is considering the lung as a single unit and providing only global readouts. However, recent advances in lung imaging modalities such as x-ray computed tomography and magnetic resonance imaging opened new doors toward obtaining both anatomical and functional information from the same scan session, without the requirement for any extra pulmonary functional measurements, in more regional and non-invasive manners. Consequently, a new field of study called pulmonary functional imaging was born which focuses on introducing new techniques for regional quantification of lung function non-invasively using imaging-based techniques. This narrative review provides first an overview of both invasive and non-invasive conventional methods for lung function measurements, mostly focused on small animals for preclinical research, including discussions about their advantages and disadvantages. Then, we focus on those newly developed, non-invasive, imaging-based techniques that can provide either global or regional lung functional readouts at multiple time-points.

Diacetyl inhalation impairs airway epithelial repair in mice infected with influenza A virus

Bronchiolitis obliterans (BO) is a debilitating disease of the small airways that can develop following exposure to toxic chemicals as well as respiratory tract infections. BO development is strongly associated with diacetyl (DA) inhalation exposures at occupationally relevant concentrations or severe influenza A viral (IAV) infections. However, it remains unclear whether lower dose exposures or more mild IAV infections can result in similar pathology. In the current work, we combined these two common environmental exposures, DA and IAV, to test whether shorter DA exposures followed by sublethal IAV infection would result in similar airways disease. Adult mice exposed to DA vapors 1 h/day for 5 consecutive days followed by infection with the airway-tropic IAV H3N2 (HKx31) resulted in increased mortality, increased bronchoalveolar lavage (BAL) neutrophil percentage, mixed obstruction and restriction by lung function, and subsequent airway remodeling. Exposure to DA or IAV alone failed to result in significant pathology, whereas mice exposed to DA + IAV showed increased α-smooth muscle actin (αSMA) and epithelial cells coexpressing the basal cell marker keratin 5 (KRT5) with the club cell marker SCGB1A1. To test whether DA exposure impairs epithelial repair after IAV infection, mice were infected first with IAV and then exposed to DA during airway epithelial repair. Mice exposed to IAV + DA developed similar airway remodeling with increased subepithelial αSMA and epithelial cells coexpressing KRT5 and SCGB1A1. Our findings reveal an underappreciated concept that common environmental insults while seemingly harmless by themselves can have catastrophic implications on lung function and long-term respiratory health when combined.

Preclinical Four-Dimensional Functional Lung Imaging and Quantification of Regional Airflow: A New Standard in Lung Function Evaluation in Murine Models

The current standard for lung function evaluation in murine models is based on forced oscillation technology, which provides a measure of the total airway function but cannot provide information on regional heterogeneity in function. Limited detection of regional airflow may contribute to a discontinuity between airway inflammation and airflow obstruction in models of asthma. Here, we describe quantification of regional airway function using novel dynamic quantitative imaging and analysis to quantify and visualize lung motion and regional pulmonary airflow in four dimensions (4D). Furthermore, temporo-spatial specific ventilation (ml/ml) is used to determine ventilation heterogeneity indices for lobar and sublobar regions, which are directly compared to ex vivo biological analyses in the same sublobar regions. In contrast, oscillation-based technology in murine genetic models of asthma have failed to demonstrate lung function change despite altered inflammation, whereas 4D functional lung imaging demonstrated diminished regional lung function in genetic models relative to wild-type mice. Quantitative functional lung imaging assists in localizing the regional effects of airflow. Our approach reveals repeatable and consistent differences in regional airflow between lung lobes in all models of asthma, suggesting that asthma is characterized by regional airway dysfunctions that are often not detectable in composite measures of lung function. 4D functional lung imaging technology has the potential to transform discovery and development in murine models by mapping out regional areas heterogeneously affected by the disease, thus deciphering pathobiology with greater precision.

Inhibition of oxidative stress, IL-13, and WNT/β-catenin in ovalbumin-sensitized rats by a novel organogel of Punica granatum seed oil saponifiable fraction

Bronchial asthma is a chronic inflammatory disease marked by inflammation, oxidative stress, and structural remodeling. Here, we prepared two pomegranate fractions from the seed oil, saponifiable (Sap) and unsaponifiable (UnSap). Two organogels (Orgs) were also formulated with the Sap (Org1) or the UnSap (Org2) fraction and beeswax (BW). All preparations were evaluated in vitro for their antioxidant and anti-inflammatory impacts. The transdermal delivery of the most efficient one was evaluated against ovalbumin (OV)-induced bronchial asthma in rats compared to dexamethasone (DEX). The results showed that the prepared pomegranate fractions and BW had considerable amounts of phenolics (flavonoids and tannins) and triterpenoids. Org1 was shown to be the most effective antioxidant and anti-inflammatory fraction with synergistic activities (combination index, 1), as well as having protective and therapeutic influences on OV-sensitized rats. Org1 inhibited the multiple OV-induced signaling pathways, comprising ROS, WNT/β-catenin, and AKT, with an efficiency superior to DEX. Subsequently, the pro-inflammatory (COX-2, NO, and IL-13), and pro-fibrotic (COL1A1) mediators, oxidative stress, and mucin secretion, were all down-regulated. These outcomes were verified by the histopathological results of lung tissue. Collectively, these outcomes suggest that the transdermal delivery of Org1 to OV-sensitized rats shows promise in the protection and treatment of the pathological hallmarks of asthma.

Regulation of the NF-κB signaling pathway and IL-13 in asthmatic rats by aerosol inhalation of the combined active constituents of Punica granatum juice and peel

Bronchial asthma is a chronic inflammatory airway illness. For the first time, we evaluated the proposed anti-asthmatic protective and therapeutic potency of inhaling Punica granatum juice (PJE) and peel (PPE) extract mixture (PM). Rats were challenged with ovalbumin (OVA) for 23 days and aerosolized with PM before each OVA challenge (protected group) or following the final OVA challenge for 3 days (therapeutic group). Considerable concentrations of phenolics were detected in PJE and PPE. Therefore, PM demonstrated synergistic scavenging abilities of NO and DPPH radicals. It also showed synergistic anti-inflammatory activities against lipopolysaccharide (LPS)-induced inflammation in the white blood cells by lowering the gene expression of CXCR1, CXCR2, IL-6, and IL-8. In addition, PM increased IL-10 gene expression while decreasing NO and TNF-α levels in LPS-exposed cells. Regarding the rats that were protected with PM, they exerted pulmonary pro-oxidant effects but prevented the OVA-induced upregulation of NF-κB, IKK, TNF-α, COX-2, iNOS, IL-13, and COL1A1, as well as MUC5AC and mucin over-secretion. While PM in the therapeutic group improved reactive oxygen species levels and normalized most of the investigated inflammatory and fibrotic mediators and mucin formation, but slightly improved the antioxidant indices. In addition, OVA-induced morphological alterations were massively improved after PM inhalation for short or long periods. Thus, PM inhalation prevented and treated OVA-induced pulmonary inflammation and fibrosis, while the inhalation period between 3 and 23 days needs to be optimized to acquire a better impact on the antioxidant indices.

Immunological Effects of Aster yomena Callus-Derived Extracellular Vesicles as Potential Therapeutic Agents against Allergic Asthma

Plant-derived extracellular vesicles, (EVs), have recently gained attention as potential therapeutic candidates. However, the varying properties of plants that are dependent on their growth conditions, and the unsustainable production of plant-derived EVs hinder drug development. Herein, we analyzed the secondary metabolites of Aster yomena callus-derived EVs (AYC-EVs) obtained via plant tissue cultures and performed an immune functional assay to assess the potential therapeutic effects of AYC-EVs against inflammatory diseases. AYC-EVs, approximately 225 nm in size, were isolated using tangential flow filtration (TFF) and cushioned ultracentrifugation. Metabolomic analysis, using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS), revealed that AYC-EVs contained 17 major metabolites. AYC-EVs inhibited the phenotypic and functional maturation of LPS-treated dendritic cells (DCs). Furthermore, LPS-treated DCs exposed to AYC-EVs showed decreased immunostimulatory capacity during induction of CD4+ and CD8+ T-cell proliferation and activation. AYC-EVs inhibited T-cell reactions associated with the etiology of asthma in asthmatic mouse models and improved various symptoms of asthma. This regulatory effect of AYC-EVs resembled that of dexamethasone, which is currently used to treat inflammatory diseases. These results provide a foundation for the development of plant-derived therapeutic agents for the treatment of various inflammatory diseases, as well as providing an insight into the possible mechanisms of action of AYC-EVs.

A Barrier to Defend - Models of Pulmonary Barrier to Study Acute Inflammatory Diseases

Pulmonary diseases represent four out of ten most common causes for worldwide mortality. Thus, pulmonary infections with subsequent inflammatory responses represent a major public health concern. The pulmonary barrier is a vulnerable entry site for several stress factors, including pathogens such as viruses, and bacteria, but also environmental factors e.g. toxins, air pollutants, as well as allergens. These pathogens or pathogen-associated molecular pattern and inflammatory agents e.g. damage-associated molecular pattern cause significant disturbances in the pulmonary barrier. The physiological and biological functions, as well as the architecture and homeostatic maintenance of the pulmonary barrier are highly complex. The airway epithelium, denoting the first pulmonary barrier, encompasses cells releasing a plethora of chemokines and cytokines, and is further covered with a mucus layer containing antimicrobial peptides, which are responsible for the pathogen clearance. Submucosal antigen-presenting cells and neutrophilic granulocytes are also involved in the defense mechanisms and counterregulation of pulmonary infections, and thus may directly affect the pulmonary barrier function. The detailed understanding of the pulmonary barrier including its architecture and functions is crucial for the diagnosis, prognosis, and therapeutic treatment strategies of pulmonary diseases. Thus, considering multiple side effects and limited efficacy of current therapeutic treatment strategies in patients with inflammatory diseases make experimental in vitro and in vivo models necessary to improving clinical therapy options. This review describes existing models for studyying the pulmonary barrier function under acute inflammatory conditions, which are meant to improve the translational approaches for outcome predictions, patient monitoring, and treatment decision-making.

An automated multi-modal graph-based pipeline for mouse genetic discovery

MOTIVATION

Our ability to identify causative genetic factors for mouse genetic models of human diseases and biomedical traits has been limited by the difficulties associated with identifying true causative factors, which are often obscured by the many false positive genetic associations produced by a GWAS.

RESULTS

To accelerate the pace of genetic discovery, we developed a graph neural network (GNN)-based automated pipeline (GNNHap) that could rapidly analyze mouse genetic model data and identify high probability causal genetic factors for analyzed traits. After assessing the strength of allelic associations with the strain response pattern; this pipeline analyzes 29M published papers to assess candidate gene-phenotype relationships; and incorporates the information obtained from a protein-protein interaction network and protein sequence features into the analysis. The GNN model produces markedly improved results relative to that of a simple linear neural network. We demonstrate that GNNHap can identify novel causative genetic factors for murine models of diabetes/obesity and for cataract formation, which were validated by the phenotypes appearing in previously analyzed gene knockout mice. The diabetes/obesity results indicate how characterization of the underlying genetic architecture enables new therapies to be discovered and tested by applying 'precision medicine' principles to murine models.

AVAILABILITY AND IMPLEMENTATION

The GNNHap source code is freely available at https://github.com/zqfang/gnnhap, and the new version of the HBCGM program is available at https://github.com/zqfang/haplomap.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Synergistic Effect of Roflumilast with Dexamethasone in a Neutrophilic Asthma Mouse Model

Asthma is a chronic airway inflammatory disease with heterogeneous features. Most cases of asthma are steroid sensitive, but 5-10% are unresponsive to steroids, leading to challenges in treatment. Neutrophilic asthma is steroid-resistant and characterized by the absence or suppression of the T_H 2 process and an increase in the T_H 1 and/or T_H 17 process. Roflumilast (ROF) has anti-inflammatory effects and has been used to treat chronic inflammatory airway diseases, such as chronic pulmonary obstructive disease. It is unclear whether ROF may have a therapeutic role in neutrophilic asthma. In this study, we investigated the synergistic effect of ROF with dexamethasone in a neutrophilic asthma mouse model. C57BL/6 female mice sensitized to ovalbumin (OVA) were exposed to five intranasal OVA treatments and three intranasal lipopolysaccharide (LPS) treatments for an additional 10 days. During the intranasal OVA challenge, ROF was administered orally, and dexamethasone (DEX) was injected intraperitoneally. Protein, pro-inflammatory cytokines, inflammatory cytokines, and other suspected markers were identified by enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blot. Following exposure to LPS in OVA-induced asthmatic mice, neutrophil predominant airway inflammation rather than eosinophil predominant inflammation was observed, with increases in airway hyperresponsiveness (AHR). The lungs of animals treated with ROF exhibited less airway inflammation and hyperresponsiveness. To investigate the mechanism underlying this effect, we examined the expression of proinflammatory cytokines suspected to be involved in inflammatory cytokines and proteins. ROF reduced total protein in bronchioalveolar lavage fluid; levels of IL-17A, IL-1β mRNA, IFN-γ, and TNF-α; and recovered histone deacetylase-2 (HDAC2) activity. Combination therapy with ROF and DEX further reduced the levels of IL-17, IL-22, and IL-1β mRNA and proinflammatory cytokines. The combination of ROF and DEX reduced lung inflammation and airway hyperresponsiveness much more than one of them alone. ROF reduces AHR and lung inflammation in the neutrophilic asthma mouse model. Furthermore, additive effects were observed when DEX was added to ROF treatment, possibly because of recovery of HDAC2/β-Actin activity. This study demonstrates the anti-inflammatory properties of ROF in a neutrophilic asthma mouse model.

Double-chamber plethysmography versus oscillometry to detect baseline airflow obstruction in a model of asthma in two mouse strains

AIM OF THE STUDY

The current gold standard to assess respiratory mechanics in mice is oscillometry, a technique from which several readouts of the respiratory system can be deduced, such as resistance and elastance. However, these readouts are often not altered in mouse models of asthma. This is in stark contrast with humans, where asthma is generally associated with alterations when assessed by either oscillometry or other techniques. In the present study, we have used double-chamber plethysmography (DCP) to evaluate the breathing pattern and the degree of airflow obstruction in a mouse model of asthma.

MATERIALS AND METHODS

Female C57BL/6 and BALB/c mice were studied at day 1 using DCP, as well as at day 11 using both DCP and oscillometry following a once-daily exposure to either house-dust mite (HDM) or saline for 10 consecutive days.

RESULTS

All DCP readouts used to describe either the breathing pattern (e.g., tidal volume and breathing frequency) or the degree of airflow obstruction (e.g., specific airway resistance) were different between mouse strains at day 1. Most of these strain differences persisted at day 11. Most oscillometric readouts (e.g., respiratory system resistance and elastance) were also different between strains. Changes caused by HDM were obvious with DCP, including decreases in tidal volume, minute ventilation, inspiratory time and mid-tidal expiratory flow and an increase in specific airway resistance. HDM also caused some strain specific alterations in breathing pattern, including increases in expiratory time and end inspiratory pause, which were only observed in C57BL/6 mice. Oscillometry also detected a small but significant increase in tissue elastance in HDM versus saline-exposed mice.

CONCLUSIONS

DCP successfully identified differences between C57BL/6 and BALB/c mice, as well as alterations in mice from both strains exposed to HDM. We conclude that, depending on the study purpose, DCP may sometimes outweigh oscillometry.

Anisakis pegreffii Extract Induces Airway Inflammation with Airway Remodeling in a Murine Model System

Exposure of the respiratory system to the Anisakis pegreffii L3 crude extract (AE) induces airway inflammation; however, the mechanism underlying this inflammatory response remains unknown. AE contains allergens that promote allergic inflammation; exposure to AE may potentially lead to asthma. In this study, we aimed to establish a murine model to assess the effects of AE on characteristic features of chronic asthma, including airway hypersensitivity (AHR), airway inflammation, and airway remodeling. Mice were sensitized for five consecutive days each week for 4 weeks. AHR, lung inflammation, and airway remodeling were evaluated 24 h after the last exposure. Lung inflammation and airway remodeling were assessed from the bronchoalveolar lavage fluid (BALF). To confirm the immune response in the lungs, changes in gene expression in the lung tissue were assessed with reverse transcription-quantitative PCR. The levels of IgE, IgG1, and IgG2a in blood and cytokine levels in the BALF, splenocyte, and lung lymph node (LLN) culture supernatant were measured with ELISA. An increase in AHR was prominently observed in AE-exposed mice. Epithelial proliferation and infiltration of inflammatory cells were observed in the BALF and lung tissue sections. Collagen deposition was detected in lung tissues. AE exposure increased IL-4, IL-5, and IL-13 expression in the lung, as well as the levels of antibodies specific to AE. IL-4, IL-5, and IL-13 were upregulated only in LLN. These findings indicate that an increase in IL-4+ CD4+ T cells in the LLN and splenocyte resulted in increased Th2 response to AE exposure. Exposure of the respiratory system to AE resulted in an increased allergen-induced Th2 inflammatory response and AHR through accumulation of inflammatory and IL-4+ CD4+ T cells and collagen deposition. It was confirmed that A. pegreffii plays an essential role in causing asthma in mouse models and has the potential to cause similar effects in humans.

Genetic variation in surfactant protein-A2 alters responses to ozone

BACKGROUND

Increased exposure to Ozone (O3) is associated with adverse health effects in individuals afflicted with respiratory diseases. Surfactant protein-A (SP-A), encoded by SP-A1 and SP-A2, is the largest protein component in pulmonary surfactant and is functionally impaired by O3-oxidation.

OBJECTIVE

We used humanized SP-A2 transgenic mice with allelic variation corresponding to a glutamine (Q) to lysine (K) amino acid substitution at position 223 in the lectin domain to determine the impact of this genetic variation in regards to O3 exposure.

METHODS

Mice were exposed to 2ppm O3 or Filtered Air (FA) for 3 hours and 24 hrs post-challenge pulmonary function tests and other parameters associated with inflammation were assessed in the bronchoalveolar lavage (BAL) fluid and lung tissue. Additionally, mouse tracheal epithelial cells were cultured and TEER measurements recorded for each genotype to determine baseline epithelial integrity.

RESULTS

Compared to FA, O3 exposure led to significantly increased sensitivity to methacholine challenge in all groups of mice. SP-A2 223Q variant mice were significantly protected from O3-induced AHR compared to SP-A-/- and SP-A2 223K mice. Neutrophilia was observed in all genotypes of mice post O3-exposure, however, SP-A2 223Q mice had a significantly lower percentage of neutrophils compared to SP-A-/- mice. Albumin levels in BAL were unchanged in O3-exposed SP-A2 223Q mice compared to their FA controls, while levels were significantly increased in all other genotypes of O3-exposed mice. SP-A 223Q MTECS has significant higher TEER values than all other genotypes, and WT MTECS has significantly higher TEER than the SP-A KO and SP-A 223K MTECS.

SIGNIFICANCE

Taken together, our study suggests that expression of a glutamine (Q) as position 223 in SP-A2, as opposed to expression of lysine (K), is more protective in acute exposures to ozone and results in attenuated O3-induced AHR, neutrophilia, and vascular permeability.

Alnus hirsuta (Spach) Rupr. Attenuates Airway Inflammation and Mucus Overproduction in a Murine Model of Ovalbumin-Challenged Asthma

Alnus hirsuta (Spach) Rupr. (AH), a member of the Betulaceae family, is widely used in Eastern Asia of as a source of medicinal compounds for the treatment of hemorrhage, diarrhea, and alcoholism. In this study, we investigated the protective effects of a methanolic extract of AH branches against airway inflammation and mucus production in tumor necrosis factor (TNF)-α-stimulated NCI-H292 cells and in an ovalbumin (OVA)-challenged allergic asthma mouse model. Female BALB/c mice were injected with OVA (40 μg) and aluminum hydroxide (2 mg) on days 0 and 14 to induce allergic airway inflammation. The mice were then challenged with 1% OVA from days 21–23. Mice were treated with AH (50 and 100 mg/kg/day; 2% DMSO) or dexamethasone (positive control; 3 mg/kg/day) from days 18–23. AH treatment effectively attenuated airway resistance/hyperresponsiveness and reduced levels of T helper type 2 (Th2) cytokines, eotaxins, and number of inflammatory cells in bronchoalveolar lavage fluid, and immunoglobulin E in serums of OVA-challenged mice. In histological analysis, AH treatment significantly inhibited airway inflammation and mucus production in OVA-challenged mice. AH treatment downregulated the phosphorylation of I kappa B-alpha, p65 nuclear factor-kappa B (p65NF-κB), and mitogen-activated protein kinases with suppression of mucin 5AC (MUC5AC) in lung tissue. Moreover, AH treatment decreased the levels of pro-inflammatory cytokines and Th2 cytokines, as well as MUC5AC expression, and inhibited the phosphorylation of p65NF-κB in TNF-α-stimulated NCI-H292 cells. These results indicate that AH might represent a useful therapeutic agent for the treatment of allergic asthma.

Nicotine in E-Cigarettes Dysregulates Pulmonary Inflammation and MMP-12 Expression without Effecting Respiratory Syncytial Virus Virulence

The safety of electronic cigarettes (e-cigarettes) is a major topic of discussion. The key goals of this study were to examine the contents of e-cigarette vapor and determine if nicotine altered inflammatory responses against respiratory syncytial virus (RSV) infection. E-cigarette vapor was passed through a hollow 3D-model of an adult lung, and gas chromatography detected over 50 compounds passed through the 3D model, including nicotine, propylene glycol (PG), ethanol, methanol, and diacetyl. The murine alveolar macrophage cell line MH-S cells were exposed to nicotine and e-cigarette vapor with and without nicotine. Nicotine significantly induced the expression of matrix metalloprotease (Mmp) 12 and reduced expression of Ifnβ and Tnfα. To examine the role of nicotine in lung defense against RSV infection, A/J mice were exposed to PBS, e-cigarette vapor with and without nicotine for 2 months before RSV infection. E-cigarette vapor did not influence RSV infection-induced animal weight loss, RSV infectivity, airway hyperresponsiveness during methacholine challenge, or immune cell infiltration into the lungs. However, e-cigarette vapor containing nicotine enhanced obstruction and induced secretion of MMP12 and reduced levels of Ifnβ and TNFα. In conclusion, nicotine in vaping products modulates immune responses that may impact the lungs during a respiratory infection.

Multiomics of World Trade Center Particulate Matter-induced Persistent Airway Hyperreactivity. Role of Receptor for Advanced Glycation End Products

Pulmonary disease after World Trade Center particulate matter (WTC-PM) exposure is associated with dyslipidemia and the receptor for advanced glycation end products (RAGE); however, the mechanisms are not well understood. We used a murine model and a multiomics assessment to understand the role of RAGE in the pulmonary long-term effects of a single high-intensity exposure to WTC-PM. After 1 month, WTC-PM-exposed wild-type (WT) mice had airway hyperreactivity, whereas RAGE-deficient (Ager^-/-) mice were protected. PM-exposed WT mice also had histologic evidence of airspace disease, whereas Ager^-/- mice remained unchanged. Inflammatory mediators such as G-CSF (granulocyte colony-stimulating factor), IP-10 (IFN-γ-induced protein 10), and KC (keratinocyte chemoattractant) were differentially expressed after WTC-PM exposure. WTC-PM induced α-SMA, DIAPH1 (protein diaphanous homolog 1), RAGE, and significant lung collagen deposition in WT compared with Ager^-/- mice. Compared with WT mice with PM exposure, relative expression of phosphorylated to total CREB (cAMP response element-binding protein) and JNK (c-Jun N-terminal kinase) was significantly increased in the lung of PM-exposed Ager^-/- mice, whereas Akt (protein kinase B) was decreased. Random forests of the refined lung metabolomic profile classified subjects with 92% accuracy; principal component analysis captured 86.7% of the variance in three components and demonstrated prominent subpathway involvement, including known mediators of lung disease such as vitamin B₆ metabolites, sphingolipids, fatty acids, and phosphatidylcholines. Treatment with a partial RAGE antagonist, pioglitazone, yielded similar fold-change expression of metabolites (N₆-carboxymethyllysine, 1-methylnicotinamide, N¹+N⁸-acetylspermidine, and succinylcarnitine [C4-DC]) between WT and Ager^-/- mice exposed to WTC-PM. RAGE can mediate WTC-PM-induced airway hyperreactivity and warrants further investigation.

Cigarette smoke induction of S100A9 contributes to chronic obstructive pulmonary disease

S100 calcium-binding protein A9 (S100A9) is elevated in plasma and bronchoalveolar lavage fluid (BALF) of patients with chronic obstructive pulmonary disease (COPD), and aging enhances S100A9 expression in several tissues. Currently, the direct impact of S100A9-mediated signaling on lung function and within the aging lung is unknown. Here, we observed that elevated S100A9 levels in human BALF correlated with age. Elevated lung levels of S100A9 were higher in older mice compared with in young animals and coincided with pulmonary function changes. Both acute and chronic exposure to cigarette smoke enhanced S100A9 levels in age-matched mice. To examine the direct role of S100A9 on the development of COPD, S100a9^-/- mice or mice administered paquinimod were exposed to chronic cigarette smoke. S100A9 depletion and inhibition attenuated the loss of lung function, pressure-volume loops, airway inflammation, lung compliance, and forced expiratory volume in 0.05 s/forced vital capacity, compared with age-matched wild-type or vehicle-administered animals. Loss of S100a9 signaling reduced cigarette smoke-induced airspace enlargement, alveolar remodeling, lung destruction, ERK and c-RAF phosphorylation, matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and keratinocyte-derived chemokine (KC) release into the airways. Paquinimod administered to nonsmoked, aged animals reduced age-associated loss of lung function. Since fibroblasts play a major role in the production and maintenance of extracellular matrix in emphysema, primary lung fibroblasts were treated with the ERK inhibitor LY3214996 or the c-RAF inhibitor GW5074, resulting in less S100A9-induced MMP-3, MMP-9, MCP-1, IL-6, and IL-8. Silencing Toll-like receptor 4 (TLR4), receptor for advanced glycation endproducts (RAGE), or extracellular matrix metalloproteinase inducer (EMMPRIN) prevented S100A9-induced phosphorylation of ERK and c-RAF. Our data suggest that S100A9 signaling contributes to the progression of smoke-induced and age-related COPD.

Pulmonary function analysis in cotton rats after respiratory syncytial virus infection

The cotton rat (Sigmodon hispidus) is an excellent small animal model for human respiratory viral infections such as human respiratory syncytial virus (RSV) and human metapneumovirus (HMPV). These respiratory viral infections, as well as other pulmonary inflammatory diseases such as asthma, are associated with lung mechanic disturbances. So far, the pathophysiological effects of viral infection and allergy on cotton rat lungs have not been measured, although this information might be an important tool to determine the efficacy of vaccine and drug candidates. To characterize pulmonary function in the cotton rat, we established forced oscillation technique in uninfected, RSV infected and HDM sensitized cotton rats, and characterized pulmonary inflammation, mucus production, pulmonary edema, and oxygenation. There was a gender difference after RSV infection, with females demonstrating airway hyper-responsiveness while males did not. Female cotton rats 2dpi had a mild increase in pulmonary edema (wet: dry weight ratios). At day 4 post infection, female cotton rats demonstrated mild pulmonary inflammation, no increase in mucus production or reduction in oxygenation. Pulmonary function was not significantly impaired after RSV infection. In contrast, cotton rats sensitized to HDM demonstrated airway hyper-responsiveness with a significant increase in pulmonary inflammation, increase in baseline tissue damping, and a decrease in baseline pulmonary compliance. In summary, we established baseline data for forced oscillation technique and other respiratory measures in the cotton rat and used it to analyze respiratory diseases in cotton rats.

Targeting c-Src Reverses Accelerated GPX-1 mRNA Decay in Chronic Obstructive Pulmonary Disease Airway Epithelial Cells

Enhanced expression of the cellular antioxidant glutathione peroxidase (GPX)-1 prevents cigarette smoke-induced lung inflammation and tissue destruction. Subjects with chronic obstructive pulmonary disease (COPD), however, have decreased airway GPX-1 levels, rendering them more susceptible to disease onset and progression. The mechanisms that downregulate GPX-1 in the airway epithelium in COPD remain unknown. To ascertain these factors, analyses were conducted using human airway epithelial cells isolated from healthy subjects and human subjects with COPD and lung tissue from control and cigarette smoke-exposed A/J mice. Tyrosine phosphorylation modifies GPX-1 expression and cigarette smoke activates the tyrosine kinase c-Src. Therefore, studies were conducted to evaluate the role of c-Src on GPX-1 levels in COPD. These studies identified accelerated GPX-1 mRNA decay in COPD airway epithelial cells. Targeting the tyrosine kinase c-Src with siRNA inhibited GPX-1 mRNA degradation and restored GPX-1 protein levels in human airway epithelial cells. In contrast, silencing the tyrosine kinase c-Abl, or the transcriptional activator Nrf2, had no effect on GPX-1 mRNA stability. The chemical inhibitors for c-Src (saracatinib and dasanitib) restored GPX-1 mRNA levels and GPX-1 activity in COPD airway cells in vitro. Similarly, saracatinib prevented the loss of lung Gpx-1 expression in response to chronic smoke exposure in vivo. Thus, this study establishes that the decreased GPX-1 expression that occurs in COPD lungs is at least partially due to accelerated mRNA decay. Furthermore, these findings show that targeting c-Src represents a potential therapeutic approach to augment GPX-1 responses and counter smoke-induced lung disease.

Lindera obtusiloba Attenuates Oxidative Stress and Airway Inflammation in a Murine Model of Ovalbumin-Challenged Asthma

Lindera obtusiloba is widespread in northeast Asia and used for treatment of improvement of blood circulation and anti-inflammation. In this study, we investigated anti-inflammatory and anti-oxidant effects of the methanolic extract of L. obtusiloba leaves (LOL) in an ovalbumin (OVA)-challenged allergic asthma model and tumor necrosis factor (TNF)-α-stimulated NCI-H292 cell. Female BALB/c mice were sensitized with OVA by intraperitoneal injection on days 0 and 14, and airway-challenged with OVA from days 21 to 23. Mice were administered 50 and 100 mg/kg of LOL by oral gavage 1 h before the challenge. LOL treatment effectively decreased airway hyper-responsiveness and inhibited inflammatory cell recruitment, Th2 cytokines, mucin 5AC (MUC5AC) in bronchoalveolar lavage fluid in OVA-challenged mice, which were accompanied by marked suppression of airway inflammation and mucus production in the lung tissue. LOL pretreatment inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) with suppression of activator protein (AP)-1 and MUC5AC in the lung tissue. LOL also down-regulated expression of inflammatory cytokines, and inhibited the activation of NF-κB in TNF-α-stimulated NCI-H292 cells. LOL elevated the translocation of nuclear factor-erythroid 2-related factor (Nrf-2) into nucleus concurrent with increase of heme oxyngenase-1 (HO-1) and NAD(P)H quinine oxidoreductase 1 (NQO1). Moreover, LOL treatment exhibited a marked increase in the anti-oxidant enzymes activities, whereas effectively suppressed the production of reactive oxygen species and nitric oxide, as well as lipid peroxidation in lung tissue of OVA-challenged mice and TNF-α-stimulated NCI-H292 cells. These findings suggest that LOL might serve as a therapeutic agent for the treatment of allergic asthma.

Targeting the interleukin-7 receptor alpha by an anti-CD127 monoclonal antibody improves allergic airway inflammation in mice

BACKGROUND

Interleukin-7 (IL-7) is the most important cytokine for T-cell homeostasis. IL-7 signals through the IL-7 receptor (IL-7R) which is composed of an alpha chain (IL-7Rα), also called CD127 and a common gamma chain. T lymphocytes, especially T helper type 2, play a crucial role in the pathobiology of allergic asthma.

OBJECTIVE

To study the effects of an anti-CD127 monoclonal antibody (mAb) in a murine model of allergic airway inflammation induced by house dust mite (HDM).

METHODS

Allergic airway inflammation was induced in mice using a protocol comprising 4 weekly percutaneous sensitizations followed by 2 weekly intranasal challenges with total HDM extracts and treated by intraperitoneal injections of an anti-CD127 mAb. Because CD127 is shared by both IL-7R and the receptor for thymic stromal lymphopoietin (TSLP), a group of mice was also treated with an anti-IL-7 mAb to block only the IL-7 signalling pathway.

RESULTS

Anti-CD127 mAb-treated mice showed significantly lower airway resistance in response to methacholine and improvement in lung histology compared with isotype mAb-treated animals. Anti-CD127 mAb treatment significantly decreased the mRNA expression of Th2 cytokines (IL-4, IL-5, and IL-13) and chemokines (CCL5/RANTES) in lung tissue, decreased the secretion of Th2 cytokines (IL-4, IL-5, and IL-13) and chemokines (CXCL1 and CCL11/eotaxin) in bronchoalveolar lavage fluid (BALF), decreased serum HDM-specific IgE, and reduced the number of total leucocytes and leucocyte subpopulations such as eosinophils, macrophages, lymphocytes, T lymphocytes, and ILC2 in BALF and lung tissue. Mice treated with anti-IL-7 mAb also showed less allergic airway inflammation as evidenced by significantly lower airway resistance and fewer leucocytes in BALF and lung tissue compared to mice treated with the corresponding isotype control mAb.

CONCLUSION AND CLINICAL RELEVANCE

Targeting the IL-7Rα by an anti-CD127 mAb improves allergic airway inflammation in mice and presents as a potential therapeutic approach for allergic asthma.

Pulmonary mechanics and structural lung development after neonatal hyperoxia in mice

BACKGROUND

Supplemental oxygen exposure administered to premature infants is associated with chronic lung disease and abnormal pulmonary function. This study used mild (40%), moderate (60%), and severe (80%) oxygen to determine how hyperoxia-induced changes in lung structure impact pulmonary mechanics in mice.

METHODS

C57BL/6J mice were exposed to room air or hyperoxia from birth through postnatal day 8. Baseline pulmonary function and methacholine challenge was assessed at 4 and 8 weeks of age, accompanied by immunohistochemical assessments of both airway (smooth muscle, tethering) and alveolar (simplification, elastin deposition) structure.

RESULTS

Mild/moderate hyperoxia increased baseline airway resistance (40% only) and airway hyperreactivity (40 and 60%) at 4 weeks accompanied by increased airway smooth muscle deposition, which resolved at 8 weeks. Severe hyperoxia increased baseline compliance, baseline resistance, and total elastin/surface area ratio without increasing airway hyperreactivity, and was accompanied by increased alveolar simplification, decreased airway tethering, and changes in elastin distribution at both time points.

CONCLUSIONS

Mild to moderate hyperoxia causes changes in airway function and airway hyperreactivity with minimal parenchymal response. Severe hyperoxia drives its functional changes through alveolar simplification, airway tethering, and elastin redistribution. These differential responses can be leveraged to further develop hyperoxia mouse models.

p19Arf Exacerbates Cigarette Smoke-Induced Pulmonary Dysfunction

Senescent cells accumulate in tissues during aging or pathological settings. The semi-genetic or pharmacological targeting of senescent cells revealed that cellular senescence underlies many aspects of the aging-associated phenotype and diseases. We previously reported that cellular senescence contributes to aging- and disease-associated pulmonary dysfunction. We herein report that the elimination of Arf-expressing cells ameliorates cigarette smoke-induced lung pathologies in mice. Cigarette smoke induced the expression of Ink4a and Arf in lung tissue with concomitant increases in lung tissue compliance and alveolar airspace. The elimination of Arf-expressing cells prior to cigarette smoke exposure protected against these changes. Furthermore, the administration of cigarette smoke extract lead to pulmonary dysfunction, which was ameliorated by subsequent senescent cell elimination. Collectively, these results suggest that senescent cells are a potential therapeutic target for cigarette smoking-associated lung disease.

Airway Resistance Caused by Sphingomyelin Synthase 2 Insufficiency in Response to Cigarette Smoke

Sphingomyelin synthase is responsible for the production of sphingomyelin (SGM), the second most abundant phospholipid in mammalian plasma, from ceramide, a major sphingolipid. Knowledge of the effects of cigarette smoke on SGM production is limited. In the present study, we examined the effect of chronic cigarette smoke on sphingomyelin synthase (SGMS) activity and evaluated how the deficiency of Sgms2, one of the two isoforms of mammalian SGMS, impacts pulmonary function. Sgms2-knockout and wild-type control mice were exposed to cigarette smoke for 6 months, and pulmonary function testing was performed. SGMS2-dependent signaling was investigated in these mice and in human monocyte-derived macrophages of nonsmokers and human bronchial epithelial (HBE) cells isolated from healthy nonsmokers and subjects with chronic obstructive pulmonary disease (COPD). Chronic cigarette smoke reduces SGMS activity and Sgms2 gene expression in mouse lungs. Sgms2-deficient mice exhibited enhanced airway and tissue resistance after chronic cigarette smoke exposure, but had similar degrees of emphysema, compared with smoke-exposed wild-type mice. Sgms2-/- mice had greater AKT phosphorylation, peribronchial collagen deposition, and protease activity in their lungs after smoke inhalation. Similarly, we identified reduced SGMS2 expression and enhanced phosphorylation of AKT and protease production in HBE cells isolated from subjects with COPD. Selective inhibition of AKT activity or overexpression of SGMS2 reduced the production of several matrix metalloproteinases in HBE cells and monocyte-derived macrophages. Our study demonstrates that smoke-regulated Sgms2 gene expression influences key COPD features in mice, including airway resistance, AKT signaling, and protease production.

Collagen VI Deficiency Results in Structural Abnormalities in the Mouse Lung

Collagen VI (COL6) is known for its role in a spectrum of congenital muscular dystrophies, which are often accompanied by respiratory dysfunction. However, little is known regarding the function of COL6 in the lung. We confirmed the presence of COL6 throughout the basement membrane region of mouse lung tissue. Lung structure and organization were studied in a previously described Col6a1^-/- mouse, which does not produce detectable COL6 in the lung. The Col6a1^-/- mouse displayed histopathologic alveolar and airway abnormalities. The airspaces of Col6a1^-/- lungs appeared simplified, with larger (29%; P < 0.01) and fewer (31%; P < 0.001) alveoli. These airspace abnormalities included reduced isolectin B4⁺ alveolar capillaries and surfactant protein C-positive alveolar epithelial type-II cells. Alterations in lung function consistent with these histopathologic changes were evident. Col6a1^-/- mice also displayed multiple airway changes, including increased branching (59%; P < 0.001), increased mucosal thickness (34%; P < 0.001), and increased epithelial cell density (13%; P < 0.001). Comprehensive transcriptome analysis revealed that the loss of COL6 is associated with reductions in integrin-paxillin-phosphatidylinositol 3-kinase signaling in vivo. In vitro, COL6 promoted steady-state phosphorylated paxillin levels and reduced cell density (16% to 28%; P < 0.05) at confluence. Inhibition of phosphatidylinositol 3-kinase, or its downstream effectors, resulted in increased cell density to a level similar to that seen on matrices lacking COL6.

Determination of reliable lung function parameters in intubated mice

Background

Animal models and, in particular, mice models, are important tools to investigate the pathogenesis of respiratory diseases and to test potential new therapeutic drugs. Lung function measurement is a key step in such investigation. In mice, it is usually performed using forced oscillation technique (FOT), negative pressure-driven forced expiratory (NPFE) and pressure-volume (PV) curve maneuvers. However, these techniques require a tracheostomy, which therefore only allows end-point measurements. Orotracheal intubation has been reported to be feasible and to give reproducible lung function measurements, but the agreement between intubation and tracheostomy generated-data remains to be tested.

Methods

Using the Flexivent system, we measured lung function parameters (in particular, forced vital capacity (FVC), forced expiratory volume in the first 0.1 s (FEV0.1), compliance (Crs) of the respiratory system, compliance (C) measured using PV loop and an estimate of inspiratory capacity (A)) in healthy intubated BALB/cJ mice and C57BL/6 J mice and compared the results with similar measurements performed in the same mice subsequently tracheostomized after intubation, by means of paired comparison method, correlation and Bland-Altman analysis. The feasibility of repetitive lung function measurements by intubation was also tested.

Results

We identified parameters that are accurately evaluated in intubated animals (i.e., FVC, FEV0.1, Crs, C and A in BALB/cJ and FVC, FEV0.1, and A in C57BL/6 J). Repetitive lung function measurements were obtained in C57BL/6 J mice.

Conclusion

This subset of lung function parameters in orotracheally intubated mice is reliable, thereby allowing relevant longitudinal studies.

Supplementary information

Supplementary information accompanies this paper at (10.1186/s12931-019-1177-9).

N6-methyladenosine-dependent primary microRNA-126 processing activated PI3K-AKT-mTOR pathway drove the development of pulmonary fibrosis induced by nanoscale carbon black particles in rats

The pulmonary fibrosis could be caused by long-term inhalation of carbon black (CB) particles. Studies on the mechanisms of pulmonary fibrosis induced by CB are required to develop the stratagem of prevention and treatment on fibrosis. The RNA-binding protein DiGeorge syndrome critical region gene 8 (DGCR8)-dependent pri-miRNAs processing is regulated by N⁶-methyladenosine (m⁶A) modification, which targets the downstream signal pathway. However, its role in pulmonary fibrosis has not been known clearly. In the present study, rats inhaled CB at dose of 0, 5 or 30 mg/m³ for 28 days, 6 h/day, respectively. The rats inhaled CB at dose of 0 or 30 mg/m³ for 14 days, 28 days and 90 days, respectively. In vitro experiments, the normal human bronchial epithelial cell line (16HBE) was treated with CB (0, 50, 100 and 200 μg/mL) for 24 h. In vitro and vivo study, the levels of fibrosis indicators including α-SMA, vimentin, collagen-I and hydroxyproline in CB treatment groups statistically increased in dose- or time- dependent manners compared with the control. After CB treatment, PI3K-AKT-mTOR pathway was activated and regulated by miRNA-126. We found that both of m⁶A modifications of pri-miRNA-126 and its binding with DGCR8 were decreased after CB treatment, which resulted in the reduction of mature miRNA-126 accompanied by accumulation of unprocessed pri-miRNA-126. This work demonstrated that m⁶A modification of pri-miRNA-126 and its binding with DGCR8 decreases blocked miRNA-126 maturation, and then activated the PI3K/AKT/mTOR pathway, which drove the fibro genesis in the lung after CB exposure.

Paracetamol inhibits Ca2+ permeant ion channels and Ca2+ sensitization resulting in relaxation of precontracted airway smooth muscle

The purpose of this study was to screen a bronchodilator from old drugs and elucidate the underlying mechanism. Paracetamol (acetaminophen) is a widely used analgesic and antipyretic drug. It has been reported that it inhibits the generation of prostaglandin and histamine, which play roles in asthma. These findings led us to explore whether paracetamol could be a potential bronchodilator. Paracetamol inhibited high K⁺- and acetylcholine (ACH)-induced precontraction of mouse tracheal and bronchial smooth muscles. Moreover, the ACH-induced contraction was partially inhibited by nifedipine (selective blocker of LVDCCs), YM-58483 (selective inhibitor of store-operated Ca²⁺ entry (SOCE), canonical transient receptor potential 3 (TRPC3) and TRPC5 channels) and Y-27632 (selective blocker of ROCK, a linker of the Ca²⁺ sensitization pathway). In single airway smooth muscle cells, paracetamol blocked the currents sensitive to nifedipine and YM-58483, and inhibited intracellular Ca²⁺ increases. In addition, paracetamol inhibited ACH-induced phosphorylation of myosin phosphatase target subunit 1 (MYPT1, another linker of the Ca²⁺ sensitization pathway). Finally, in vivo paracetamol inhibited ACH-induced increases of mouse respirator system resistance. Collectively, we conclude that paracetamol inhibits ASM contraction through blocking LVDCCs, SOCE and/or TRPC3 and/or TRPC5 channels, and Ca²⁺ sensitization. These results suggest that paracetamol might be a new bronchodilator.

Chronic Cigarette Smoke Exposure Subdues PP2A Activity by Enhancing Expression of the Oncogene CIP2A

Phosphatase activity of the major serine threonine phosphatase, protein phosphatase 2A (PP2A), is blunted in the airways of individuals with chronic obstructive pulmonary disease (COPD), which results in heightened inflammation and proteolytic responses. The objective of this study was to investigate how PP2A activity is modulated in COPD airways. PP2A activity and endogenous inhibitors of PP2A were investigated in animal and cell models of COPD. In primary human bronchial epithelial (HBE) cells isolated from smokers and donors with COPD, we observed enhanced expression of cancerous inhibitor of PP2A (CIP2A), an oncoprotein encoded by the KIAA1524 gene, compared with cells from nonsmokers. CIP2A expression was induced by chronic cigarette smoke exposure in mice that coincided with a reduction in PP2A activity, airspace enlargements, and loss of lung function, as determined by PP2A phosphatase activity, mean linear intercept analysis, and forced expiratory volume in 0.05 second/forced vital capacity. Modulating CIP2A expression in HBE cells by silencing RNA or chemically with erlotinib enhanced PP2A activity, reduced extracellular-signal-regulated kinase phosphorylation, and reduced the responses of matrix metalloproteinases 1 and 9 in HBE cells isolated from subjects with COPD. Enhanced epithelial growth factor receptor responses in cells from subjects with COPD were observed to modulate CIP2A expression levels. Our study indicates that chronic cigarette smoke induction of epithelial growth factor receptor signaling and CIP2A expression can impair PP2A responses that are associated with loss of lung function and enhancement of proteolytic responses. Augmenting PP2A activity by manipulating CIP2A expression may represent a feasible therapeutic approach to counter smoke-induced lung disease.

Protein Phosphatase 2A Reduces Cigarette Smoke-induced Cathepsin S and Loss of Lung Function

Rationale: CTSS (cathepsin S) is a cysteine protease that is observed at higher concentrations in BAL fluid and plasma of subjects with chronic obstructive pulmonary disease (COPD). Objectives: To investigate whether CTSS is involved in the pathogenesis of cigarette smoke-induced COPD and determine whether targeting upstream signaling could prevent the disease. Methods: CTSS expression was investigated in animal and human tissue and cell models of COPD. Ctss-/- mice were exposed to long-term cigarette smoke and forced oscillation and expiratory measurements were recorded. Animals were administered chemical modulators of PP2A (protein phosphatase 2A) activity. Measurements and Main Results: Here we observed enhanced CTSS expression and activity in mouse lungs after exposure to cigarette smoke. Ctss-/- mice were resistant to cigarette smoke-induced inflammation, airway hyperresponsiveness, airspace enlargements, and loss of lung function. CTSS expression was negatively regulated by PP2A in human bronchial epithelial cells isolated from healthy nonsmokers and COPD donors and in monocyte-derived macrophages. Modulating PP2A expression or activity, with silencer siRNA or a chemical inhibitor or activator, during acute smoke exposure in mice altered inflammatory responses and CTSS expression and activity in the lung. Enhancement of PP2A activity prevented chronic smoke-induced COPD in mice. Conclusions: Our study indicates that the decrease in PP2A activity that occurs in COPD contributes to elevated CTSS expression in the lungs and results in impaired lung function. Enhancing PP2A activity represents a feasible therapeutic approach to reduce CTSS activity and counter smoke-induced lung disease.

Relaxant Action of Diclofenac Sodium on Mouse Airway Smooth Muscle

Diclofenac sodium (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) and is widely used as an analgesic and anti-inflammatory agent. Herein, we found that DCF could relax high K+ (80 mM K+)-/ACh-precontracted tracheal rings (TRs) in mice. This study aimed to elucidate the underlying mechanisms of DCF-induced relaxations. The effects of DCF on airway smooth muscle (ASM) cells were explored using multiple biophysiological techniques, such as isometric tension measurement and patch-clamping experiments. Both high K+- and ACh-evoked contraction of TRs in mice were relaxed by DCF in a dose-dependent manner. The results of isometric tension and patch-clamping experiments demonstrated that DCF-induced relaxation in ASM cells was mediated by cytosolic free Ca2+, which was decreased via inhibition of voltage-dependent L-type Ca2+ channels (VDLCCs), nonselective cation channels (NSCCs), and Na+/Ca2+ exchange. Meanwhile, DCF also enhanced large conductance Ca2+ activated K+ (BK) channels, which led to the relaxation of ASMs. Our data demonstrated that DCF relaxed ASMs by decreasing the intracellular Ca2+ concentration via inhibition of Ca2+ influx and Na+/Ca2+ exchange. Meanwhile, the enhanced BK channels also played a role in DCF-induced relaxation in ASMs. These results suggest that DCF is a potential candidate for antibronchospasmic drugs used in treating respiratory diseases such as asthma and chronic obstructive pulmonary disease.

Regenerative therapy based on miRNA-302 mimics for enhancing host recovery from pneumonia caused by Streptococcus pneumoniae

Bacterial pneumonia remains a leading cause of morbidity and mortality worldwide. A defining feature of pneumonia is lung injury, leading to protracted suffering and vulnerability long after bacterial clearance. Little is known about which cells are damaged during bacterial pneumonia and if the regenerative process can be harnessed to promote tissue repair and host recovery. Here, we show that infection of mice with Streptococcus pneumoniae (Sp) caused substantial damage to alveolar epithelial cells (AEC), followed by a slow process of regeneration. Concurrent with AEC regeneration, the expression of miRNA-302 is elevated in AEC. Treatment of Sp-infected mice with miRNA-302 mimics improved lung functions, host recovery, and survival. miRNA-302 mediated its therapeutic effects, not by inhibiting apoptosis and preventing damage, but by promoting proliferation of local epithelial progenitor cells to regenerate AEC. These results demonstrate the ability of microRNA-based therapy to promote AEC regeneration and enhance host recovery from bacterial pneumonia.

Club Cell Secretory Protein Deficiency Leads to Altered Lung Function

RATIONALE

CC16 (club cell secretory protein-16), a member of the secretoglobin family, is one of the most abundant proteins in normal airway secretions and has been described as a serum biomarker for obstructive lung diseases.

OBJECTIVES

To determine whether low CC16 is a marker for airway pathology or is implicated in the pathophysiology of progressive airway damage in these conditions.

METHODS

Using human data from the birth cohort of the Tucson Children's Respiratory Study, we examined the relation of circulating CC16 levels with pulmonary function and responses to bronchial methacholine challenge from childhood up to age 32 years. In wild-type and CC16-/- mice, we set out to comprehensively examine pulmonary physiology, inflammation, and remodeling in the naive airway.

MEASUREMENTS AND MAIN RESULTS

We observed that Tucson Children's Respiratory Study participants in the lowest tertile of serum CC16 had significant deficits in their lung function and enhanced airway hyperresponsiveness to methacholine challenge from 11 years throughout young adult life. Similarly, CC16-/- mice had significant deficits in lung function and enhanced airway hyperresponsiveness to methacholine as compared with wild-type mice, which were independent of inflammation and mucin production. As compared with wild-type mice, CC16-/- mice had significantly elevated gene expression of procollagen type I, procollagen type III, and α-smooth muscle actin, areas of pronounced collagen deposition and significantly enhanced smooth muscle thickness.

CONCLUSIONS

Our findings support clinical observations by providing evidence that lack of CC16 in the lung results in dramatically altered pulmonary function and structural alterations consistent with enhanced remodeling.

A bronchoprotective role for Rgs2 in a murine model of lipopolysaccharide-induced airways inflammation

Background

Asthma exacerbations are associated with the recruitment of neutrophils to the lungs. These cells release proteases and mediators, many of which act at G protein-coupled receptors (GPCRs) that couple via Gq to promote bronchoconstriction and inflammation. Common asthma therapeutics up-regulate expression of the regulator of G protein signalling (RGS), RGS2. As RGS2 reduces signaling from Gq-coupled GPCRs, we have defined role(s) for this GTPase-activating protein in an acute neutrophilic model of lung inflammation.

Methods

Wild type and Rgs2^−/− C57Bl6 mice were exposed to nebulized lipopolysaccharide (LPS). Lung function (respiratory system resistance and compliance) was measured using a SCIREQ flexivent small animal ventilator. Lung inflammation was assessed by histochemistry, cell counting and by cytokine and chemokine expression in bronchoalveolar lavage (BAL) fluid.

Results

Lipopolysaccharide inhalation induced transient airways hyperreactivity (AHR) and neutrophilic lung inflammation. While AHR and inflammation was greatest 3 h post-LPS exposure, BAL neutrophils persisted for 24 h. At 3 h post-LPS inhalation, multiple inflammatory cytokines (CSF2, CSF3, IL6, TNF) and chemokines (CCL3, CCL4, CXCL1, CXCL2) were highly expressed in the BAL fluid, prior to declining by 24 h. Compared to wild type counterparts, Rgs2^−/− mice developed significantly greater airflow resistance in response to inhaled methacholine (MCh) at 3 h post-LPS exposure. At 24 h post-LPS exposure, when lung function was recovering in the wild type animals, MCh-induced resistance was increased, and compliance decreased, in Rgs2^−/− mice. Thus, Rgs2^−/− mice show AHR and stiffer lungs 24 h post-LPS exposure. Histological markers of inflammation, total and differential cell counts, and major cytokine and chemokine expression in BAL fluid were similar between wild type and Rgs2^−/− mice. However, 3 and 24 h post-LPS exposure, IL12B expression was significantly elevated in BAL fluid from Rgs2^−/− mice compared to wild type animals.

Conclusions

While Rgs2 is bronchoprotective in acute neutrophilic inflammation, no clear anti-inflammatory effect was apparent. Nevertheless, elevated IL12B expression in Rgs2^−/− animals raises the possibility that RGS2 could dampen Th1 responses. These findings indicate that up-regulation of RGS2, as occurs in response to inhaled corticosteroids and long-acting β₂-adrenoceptor agonists, may be beneficial in acute neutrophilic exacerbations of airway disease, including asthma.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0266-5) contains supplementary material, which is available to authorized users.

Elimination of p19ARF -expressing cells protects against pulmonary emphysema in mice

Senescent cells accumulate in tissues during aging and are considered to underlie several aging‐associated phenotypes and diseases. We recently reported that the elimination of p19^ARF‐expressing senescent cells from lung tissue restored tissue function and gene expression in middle‐aged (12‐month‐old) mice. The aging of lung tissue increases the risk of pulmonary diseases such as emphysema, and cellular senescence is accelerated in emphysema patients. However, there is currently no direct evidence to show that cellular senescence promotes the pathology of emphysema, and the involvement of senescence in the development of this disease has yet to be clarified. We herein demonstrated that p19^ARF facilitated the development of pulmonary emphysema in mice. The elimination of p19^ARF‐expressing cells prevented lung tissue from elastase‐induced lung dysfunction. These effects appeared to depend on reduced pulmonary inflammation, which is enhanced after elastase stimulation. Furthermore, the administration of a senolytic drug that selectively kills senescent cells attenuated emphysema‐associated pathologies. These results strongly suggest the potential of senescent cells as therapeutic/preventive targets for pulmonary emphysema.

Identification of Mepenzolate Derivatives With Long-Acting Bronchodilatory Activity

The standard treatment for chronic obstructive pulmonary disease is a combination of anti-inflammatory drugs and bronchodilators. We recently found that mepenzolate bromide (MP), an antagonist for human muscarinic M3 receptor (hM₃R), has both anti-inflammatory and short-acting bronchodilatory activities. To obtain MP derivatives with longer-lasting bronchodilatory activity, we synthesized hybrid compounds based on MP and two other muscarinic antagonists with long-acting bronchodilatory activity glycopyrronium bromide (GC) and aclidinium bromide (AD). Of these three synthesized hybrid compounds (MP-GC, GC-MP, MP-AD) and MP, MP-AD showed the highest affinity for hM₃R and had the longest lasting bronchodilatory activity, which was equivalent to that of GC and AD. Both MP-GC and MP-AD exhibited an anti-inflammatory effect equivalent to that of MP, whereas, in line with GC and AD, GC-MP did not show this effect. We also confirmed that administration of MP-AD suppressed elastase-induced pulmonary emphysema in a mouse model. These findings provide important information about the structure-activity relationship of MP for both bronchodilatory and anti-inflammatory activities.

Time-dependent distinct roles of Toll-like receptor 4 in a house dust mite-induced asthma mouse model

House dust mites (HDMs) are a common source of allergens that trigger both allergen-specific and innate immune responses in humans. Here, we examined the effect of allergen concentration and the involvement of Toll-like receptor 4 (TLR4) in the process of sensitization to house dust mite allergens in an HDM extract-induced asthma mouse model.　Intranasal administration of HDM extract induced an immunoglobulin E response and eosinophilic inflammation in a dose-dependent manner from 2.5 to 30 μg/dose. In TLR4-knockout mice, the infiltration of eosinophils and neutrophils into the lung was decreased compared with that in wild-type mice in the early phase of inflammation (total of three doses). However, in the late phase of inflammation (total of seven doses), eosinophil infiltration was significantly greater in TLR4-knockout mice than in wild-type mice. This suggests that the roles of TLR4 signaling are different between the early phase and the later phase of HDM allergen-induced inflammation. Thus, innate immune response through TLR4 regulated the response to HDM allergens, and the regulation was altered during the phase of inflammation.

Differential effects of innate immune variants of surfactant protein-A1 (SFTPA1) and SP-A2 (SFTPA2) in airway function after Klebsiella pneumoniae infection and sex differences

Background

Surfactant Protein-A (SP-A) is a major protein component of surfactant and plays a role in surfactant-related functions and innate immunity. Human SP-A consists of two functional genes, SFTPA1 and SFTPA2, encoding SP-A1 and SP-A2 proteins, respectively and each is identified with numerous genetic variants. These differentially enhance bacterial phagocytosis, with SP-A2 variants being more effective than SP-A1.

Methods

Lung functions of humanized transgenic (hTG) mice that carry different SP-A1 and SP-A2 variants or both variants SP-A1/SP-A2 (6A²/1A⁰, co-ex), as well as SP-A knockout (KO), were studied. The animals were connected to a flexiVent system to obtain forced oscillation technique (FOT) measurements and the data were analyzed using various models. Lung function was assessed after infection (baseline) and following inhaled methacholine concentrations (0–50 mg/mL).

Results

Here, we investigated the role of SP-A variants on airway function after Klebsiella pneumoniae (Kp) infection (baseline) and following inhaled methacholine. We found that: 1) in the absence of methacholine no significant differences were observed between SP-A1 and SP-A2 variants and/or SP-A knockout (KO) except for sex differences in most of the parameters studied. 2) In response to methacholine, i) sex differences were observed that were reverse of those observed in the absence of methacholine; ii) SP-A2 (1A³) gene variant in males exhibited increased total and central airway resistance (Rrs and Rn) versus all other variants; iii) In females, SP-A2 (1A³) and SP-A1 (6A²) variants had similar increases in total and central airway resistance (Rrs and Rn) versus all other variants; iv) Allele-specific differences were observed, a) with SP-A2 (1A³) exhibiting significantly higher lung functions versus SP-A2 (1A⁰) in both sexes, except for Crs, and b) SP-A1 (6A², 6A⁴) had more diverse changes in lung function in both sexes.

Conclusion

We conclude that, in response to infection and methacholine, SP-A variants differentially affect lung function and exhibit sex-specific differences consistent with previously reported findings of functional differences of SP-A variants. Thus, the observed changes in respiratory function mechanics provide insight into the role and importance of genetic variation of innate immune molecules, such as SP-A, on mechanical consequences of lung function after infection and inhaled substances.