Asthmatic Airway Epithelium Research Articles

Necroptosis plays a role in TL1A-induced airway inflammation and barrier damage in asthma

BackgroundAirway epithelial cell (AEC) necroptosis contributes to airway allergic inflammation and asthma exacerbation. Targeting the tumor necrosis factor-like ligand 1 A (TL1A)/death receptor 3 (DR3) axis has a therapeutic effect on asthmatic airway inflammation. The role of TL1A in mediating necroptosis of AECs challenged with ovalbumin (OVA) and its contribution to airway inflammation remains unclear.MethodsWe evaluated the expression of the receptor-interacting serine/threonine-protein kinase 3(RIPK3) and the mixed lineage kinase domain-like protein (MLKL) in human serum and lung, and histologically verified the level of MLKL phosphorylation in lung tissue from asthmatics and OVA-induced mice. Next, using MLKL knockout mice and the RIPK3 inhibitor GSK872, we investigated the effects of TL1A on airway inflammation and airway barrier function through the activation of necroptosis in experimental asthma.ResultsHigh expression of necroptosis marker proteins was observed in the serum of asthmatics, and necroptosis was activated in the airway epithelium of both asthmatics and OVA-induced mice. Blocking necroptosis through MLKL knockout or RIPK3 inhibition effectively attenuated parabronchial inflammation, mucus hypersecretion, and airway collagen fiber accumulation, while also suppressing type 2 inflammatory factors secretion. In addition, TL1A/ DR3 was shown to act as a death trigger for necroptosis in the absence of caspases by silencing or overexpressing TL1A in HBE cells. Furthermore, the recombinant TL1A protein was found to induce necroptosis in vivo, and knockout of MLKL partially reversed the pathological changes induced by TL1A. The necroptosis induced by TL1A disrupted the airway barrier function by decreasing the expression of tight junction proteins zonula occludens-1 (ZO-1) and occludin, possibly through the activation of the NF-κB signaling pathway.ConclusionsTL1A-induced airway epithelial necroptosis plays a significant role in promoting airway inflammation and barrier dysfunction in asthma. Inhibition of the TL1A-induced necroptosis pathway could be a promising therapeutic strategy.

Targeting lysyl oxidase like 2 attenuates OVA-induced airway remodeling partly via the AKT signaling pathway

BackgroundAirway epithelium is an important component of airway structure and the initiator of airway remodeling in asthma. The changes of extracellular matrix (ECM), such as collagen deposition and structural disturbance, are typical pathological features of airway remodeling. Thus, identifying key mediators that derived from airway epithelium and capable of modulating ECM may provide valuable insights for targeted therapy of asthma.MethodsThe datasets from Gene Expression Omnibus database were analyzed to screen differentially expressed genes in airway epithelium of asthma. We collected bronchoscopic biopsies and serum samples from asthmatic and healthy subjects to assess lysyl oxidase like 2 (LOXL2) expression. RNA sequencing and various experiments were performed to determine the influences of LOXL2 knockdown in ovalbumin (OVA)-induced mouse models. The roles and mechanisms of LOXL2 in bronchial epithelial cells were explored using LOXL2 small interfering RNA, overexpression plasmid and AKT inhibitor.ResultsBoth bioinformatics analysis and further experiments revealed that LOXL2 is highly expressed in airway epithelium of asthmatics. In vivo, LOXL2 knockdown significantly inhibited OVA-induced ECM deposition and epithelial-mesenchymal transition (EMT) in mice. In vitro, the transfection experiments on 16HBE cells demonstrated that LOXL2 overexpression increases the expression of N-cadherin and fibronectin and reduces the expression of E-cadherin. Conversely, after silencing LOXL2, the expression of E-cadherin is up-regulated. In addition, the remodeling and EMT process that induced by transforming growth factor-β1 could be enhanced and weakened after LOXL2 overexpression and silencing in 16HBE cells. Combining the RNA sequencing of mouse lung tissues and experiments in vitro, LOXL2 was involved in the regulation of AKT signaling pathway. Moreover, the treatment with AKT inhibitor in vitro partially alleviated the consequences associated with LOXL2 overexpression.ConclusionsTaken together, the results demonstrated that epithelial LOXL2 plays a role in asthmatic airway remodeling partly via the AKT signaling pathway and highlighted the potential of LOXL2 as a therapeutic target for airway remodeling in asthma.

Elevated PLAUR is observed in the airway epithelium of asthma patients and blocking improves barrier integrity.

Expression of the urokinase plasminogen activator receptor (uPAR) is elevated in the airway epithelium in asthma; however, the contribution of uPAR to asthma pathogenesis and scope for therapeutic targeting remains unknown. To determine (i) the expression profile of uPAR in cultured human bronchial epithelial cells (HBEC) from asthma patients, (ii) the relationship between uPAR and the epithelial barrier, including blocking uPAR functions and (iii) the function of different uPAR isoforms. uPAR levels in HBECs isolated from asthma patients and cells at air liquid interface (ALI) during differentiation were quantified. Transepithelial electrical resistance or electrical cell impedance sensing was used to relate uPAR levels to barrier properties, including effects of uPAR blocking antibodies. The functional effects of gain of function was determined using transcriptomics, in cells over-expressing membrane (muPAR), soluble cleaved (scuPAR) or soluble spliced (ssuPAR) isoforms. Elevated expression of uPAR was a feature of cultured HBECs from asthma patients, suggesting intrinsic alterations in asthma patient cells. Soluble uPAR levels inversely correlated with barrier properties of the HBEC layer in 2D and ALI. Blocking uPAR-integrin interactions enhanced barrier formation. The gain of function cells showed limited transcriptomic changes. This study provides a significant advance in our understanding of the relationship between asthma, uPAR and the epithelial barrier, where elevated circulating uPAR results in a reduced cell barrier, a phenotype prevalent in asthma.

The Dual Role of the Airway Epithelium in Asthma: Active Barrier and Regulator of Inflammation.

Chronic airway inflammation is the cornerstone on which bronchial asthma arises, and in turn, chronic inflammation arises from a complex interplay between environmental factors such as allergens and pathogens and immune cells as well as structural cells constituting the airway mucosa. Airway epithelial cells (AECs) are at the center of these processes. On the one hand, they represent the borderline separating the body from its environment in order to keep inner homeostasis. The airway epithelium forms a multi-tiered, self-cleaning barrier that involves an unstirred, discontinuous mucous layer, the dense and rigid mesh of the glycocalyx, and the cellular layer itself, consisting of multiple, densely interconnected cell types. On the other hand, the airway epithelium represents an immunologically highly active tissue once its barrier has been penetrated: AECs play a pivotal role in releasing protective immunoglobulin A. They express a broad spectrum of pattern recognition receptors, enabling them to react to environmental stressors that overcome the mucosal barrier. By releasing alarmins-proinflammatory and regulatory cytokines-AECs play an active role in the formation, strategic orientation, and control of the subsequent defense reaction. Consequently, the airway epithelium is of vital importance to chronic inflammatory diseases, such as asthma.

Airway epithelium IgE-FcεRI cross-link induces epithelial barrier disruption in severe T2-high asthma

Although high-affinity immunoglobulin (Ig)E receptor (FcεRI) expression is upregulated in type 2 (T2)-high asthmatic airway epithelium, its functional role in airway epithelial dysfunction has not been elucidated. Here we report the upregulated expression of FcεRI and p-EGFR (Epidermal Growth Factor Receptor), associated with decreased expression of E-cadherin and claudin-18 in bronchial biopsies of severe T2-high asthmatics compared to mild allergic asthmatics and non-T2 asthmatics. Monomeric IgE (mIgE) decreased the expression of junction proteins, E-cadherin, claudin-18, and ZO-1, and increased alarmin messenger RNA and protein expression in cultured primary bronchial epithelial cells from T2-high asthmatics. Epithelial FcεRI ligation with mIgE decreased transepithelial electric resistance in air-liquid interface cultured epithelial cells. FcεRI ligation with mIgE or IgE- Dinitrophenyl or serum of high-level allergen-specific IgE activated EGFR and Akt via activation of Src family kinases, mediating alarmin expression, junctional protein loss, and increased epithelial permeability. Furthermore, tracheal instillation of mIgE in house dust mite-sensitized mice induced airway hyper-responsiveness, junction protein loss, epithelial cell shedding, and increased epithelial permeability. Thus, our results suggest that IgE-FcεRI cross-linking in the airway epithelium is a potential and unnoticed mechanism for impaired barrier function, increased mucosal permeability, and EGFR-mediated alarmin production in T2-high asthma.

A human model of asthma exacerbation reveals transcriptional programs and cell circuits specific to allergic asthma.

Asthma is a chronic disease most commonly associated with allergy and type 2 inflammation. However, the mechanisms that link airway inflammation to the structural changes that define asthma are incompletely understood. Using a human model of allergen-induced asthma exacerbation, we compared the lower airway mucosa in allergic asthmatics and allergic non-asthmatic controls using single-cell RNA sequencing. In response to allergen, the asthmatic airway epithelium was highly dynamic and up-regulated genes involved in matrix degradation, mucus metaplasia, and glycolysis while failing to induce injury-repair and antioxidant pathways observed in controls. IL9-expressing pathogenic TH2 cells were specific to asthmatic airways and were only observed after allergen challenge. Additionally, conventional type 2 dendritic cells (DC2 that express CD1C) and CCR2-expressing monocyte-derived cells (MCs) were uniquely enriched in asthmatics after allergen, with up-regulation of genes that sustain type 2 inflammation and promote pathologic airway remodeling. In contrast, allergic controls were enriched for macrophage-like MCs that up-regulated tissue repair programs after allergen challenge, suggesting that these populations may protect against asthmatic airway remodeling. Cellular interaction analyses revealed a TH2-mononuclear phagocyte-basal cell interactome unique to asthmatics. These pathogenic cellular circuits were characterized by type 2 programming of immune and structural cells and additional pathways that may sustain and amplify type 2 signals, including TNF family signaling, altered cellular metabolism, failure to engage antioxidant responses, and loss of growth factor signaling. Our findings therefore suggest that pathogenic effector circuits and the absence of proresolution programs drive structural airway disease in response to type 2 inflammation.

DOCK2 Promotes Asthma Development by Eliciting Airway Epithelial-Mesenchymal Transition.

Epithelial-mesenchymal transition (EMT) contributes to airway remodeling, a predominant feature of asthma. DOCK2 (dedicator of cytokinesis 2) is an innate immune signaling molecule involved in vascular remodeling. However, it is unknown if DOCK2 plays a role in airway remodeling during asthma development. In this study, we found that DOCK2 is highly induced in both normal human bronchial epithelial cells treated with house dust mite (HDM) extract and human asthmatic airway epithelium. DOCK2 is also upregulated by TGF-β1 (transforming growth factor β1) during EMT of human bronchial epithelial cells. Importantly, knockdown of DOCK2 inhibits, and overexpression of DOCK2 promotes, TGF-β1-induced EMT. Consistently, DOCK2 deficiency suppresses the EMT of airway epithelium, attenuates the subepithelial fibrosis, and improves pulmonary function in HDM-induced asthmatic lungs. These data suggest that DOCK2 plays an important role in EMT and asthma development. Mechanistically, DOCK2 interacts with transcription factor FoxM1 (forkhead box M1), which enhances FoxM1 binding to mesenchymal marker gene promoters and further promotes mesenchymal marker gene transcription and expression, leading to EMT. Taken together, our study identifies DOCK2 as a novel regulator for airway EMT in an HDM-induced asthma model, thus providing a potential therapeutic target for treatment of asthma.

Rhinovirus infection of the airway epithelium enhances mast cell immune responses via epithelial-derived interferons

Mast cells (MCs) within the airway epithelium in asthma are closely related to airway dysfunction, but cross talk between airway epithelial cells (AECs) and MCs in asthma remains incompletely understood. Human rhinovirus (RV) infections are key triggers for asthma progression, and AECs from individuals with asthma may have dysregulated antiviral responses. We utilized primary AECs in an exvivo coculture model system to examine cross talk between AECs and MCs after epithelial rhinovirus infection. Primary AECs were obtained from 11 children with asthma and 10 healthy children, differentiated at air-liquid interface, and cultured in the presence of laboratory of allergic diseases 2 (LAD2) MCs. AECs were infected with rhinovirus serogroup A16 (RV16) for 48 hours. RNA isolated from both AECs and MCs underwent RNA sequencing. Direct effects of epithelial-derived interferons on LAD2 MCs were examined by real-time quantitative PCR. MCs increased expression of proinflammatory and antiviral genes in AECs. AECs demonstrated a robust antiviral response after RV16 infection that resulted in significant changes in MC gene expression, including upregulation of genes involved in antiviral responses, leukocyte activation, and type 2 inflammation. Subsequent exvivo modeling demonstrated that IFN-β induces MC type 2 gene expression. The effects of AEC donor phenotype were small relative to the effects of viral infection and the presence of MCs. There is significant cross talk between AECs andMCs, which are present in the epithelium in asthma. Epithelial-derived interferons not only play a role in viral suppression but also further alter MC immune responses including specific type 2 genes.

House dust mite-induced endoplasmic reticulum stress mediates MUC5AC hypersecretion via TBK1 in airway epithelium

Purpose: Endoplasmic reticulum (ER) stress regulates mucus hypersecretion, and may activate downstream factors via TBK1 signaling to induce gene expression. However, it remains unclear whether ER stress promotes airway mucus secretion through the TBK1 pathway. We aimed to investigate the role of the TBK1 pathway in the regulation of MUC5AC expression in a mouse model of house dust mite (HDM)-induced allergic asthma. Materials and Methods: Mice with HDM-induced asthma and human bronchial epithelial BEAS-2B cells were treated with amlexanox, an anti-allergy drug (25 μM), or 4-PBA (10 mM). Tissue and cell samples were collected. Tissue samples were stained with hematoxylin and eosin (H&E) or periodic acid Schiff (PAS) to evaluate pathology. Protein expression was analyzed by western blotting and immunofluorescence. Results: Mice exposed to HDM presented ER stress and hypersecretion of mucus Muc5ac from airway epithelial cells (p < 0.001). Similar results were observed in BEAS-2B cells following exposure to HDM. Both in vivo and in vitro studies revealed that HDM-induced ER stress induced MUC5AC overexpression via TBK1 signaling. Amlexanox and 4-PBA markedly reduced mucus production and weakened the TBK1 signal, which mediates MUC5AC hypersecretion. Conclusion: TBK1 plays a pivotal role in HDM-induced ER stress, leading to overproduction of MUC5AC in the asthmatic airway epithelium. The overproduction of MUC5AC can be significantly decreased by inhibiting TBK1 or ER stress using 4-PBA. These findings highlight potential target-specific therapies for patients with chronic allergic asthma.

Vitamin A-regulated ciliated cells promote airway epithelium repair in an asthma mouse model.

Asthma is a chronic inflammatory airway disease that causes damage to and exfoliation of the airway epithelium. The continuous damage to the airway epithelium in asthma cannot be repaired quickly and generates irreversible damage, repeated attacks, and aggravation. Vitamin A (VA) has multifarious biological functions that include maintaining membrane stability and integrity of the structure and function of epithelial cells. Our research explored the role of VA in repairing the airway epithelium and provided a novel treatment strategy for asthma. A mouse asthma model was established by house dust mite (HDM) and treated with VA by gavage. Human bronchial epithelial (16HBE) cells were treated with HDM and all-trans retinoic acid (ATRA) in vitro. We analyzed the mRNA and protein expression of characteristic markers, such as acetyl-α-tubulin (Ac-TUB) and FOXJ1 in ciliated cells and MUC5AC in secretory cells, mucus secretion, airway inflammation, the morphology of cilia, and the integrity of the airway epithelium. Findings showed destruction of airway epithelial integrity, damaged cilia, high mucus secretion, increased MUC5AC expression, and decreased Ac-TUB and FOXJ1 expression in asthmatic mice. The VA intervention reversed the effect on Ac-TUB and FOXJ1 and promoted ciliated cells to repair the damage and maintain airway epithelial integrity. In 16HBE cells, we could confirm that ATRA promoted the expression of Ac-TUB and FOXJ1. These results demonstrated that VA-regulated ciliated cells to repair the damaged airway epithelium caused by asthma and maintain airway epithelial integrity. VA intervention is a potential adjunct to conventional treatment for asthma.

Role of airway epithelial cell miRNAs in asthma.

The airway epithelial cells and overlying layer of mucus are the first point of contact for particles entering the lung. The severity of environmental contributions to pulmonary disease initiation, progression, and exacerbation is largely determined by engagement with the airway epithelium. Despite the cellular cross-talk and cargo exchange in the microenvironment, epithelial cells produce miRNAs associated with the regulation of airway features in asthma. In line with this, there is evidence indicating miRNA alterations related to their multifunctional regulation of asthma features in the conducting airways. In this review, we discuss the cellular components and functions of the airway epithelium in asthma, miRNAs derived from epithelial cells in disease pathogenesis, and the cellular exchange of miRNA-bearing cargo in the airways.

Genomic evidence for dysregulated glutamine metabolism inthe asthmatic airway epithelium.

Genomic evidence for dysregulated glutamine metabolism inthe asthmatic airway epithelium.

KIF2A decreases IL-33 production and attenuates allergic asthmatic inflammation

BackgroundThe microtubule-dependent molecular motor protein Kinesin Family Member 2A (KIF2A) is down-regulated in asthmatic human airway epithelium. However, little is known about the roles of KIF2A as well as the possible underlying mechanisms in asthma.MethodsHouse dust mite (HDM) extract was administered to establish a murine model of asthma. The expression of KIF2A, IL-33 and the autophagy pathways were detected. The plasmid pCMV-KIF2A was used to overexpress KIF2A in the airway epithelial cells in vitro and in vivo. IL-4, IL-5, IL-33 and other cytokines in bronchoalveolar lavage fluid (BALF) and lung tissues homogenates were measured.ResultsIn response to the challenge of house dust mite (HDM) in vitro and in vivo, airway epithelial cells displayed decreased production of KIF2A. Meanwhile, autophagy and IL-33 were increased in HMD-treated epithelial cells. Mechanistically, KIF2A decreased autophagy via suppressing mTORC1 pathway in HDM-treated epithelial cells, which contributed to the reduced production of IL-33. Moreover, in vivo KIF2A transfection reduced IL-33 and autophagy in the lung, leading to the attenuation of allergic asthma.ConclusionKIF2A suppressed mTORC1-mediated autophagy and decreased the production of epithelial-derived cytokine IL-33 in allergic airway inflammation. These data indicate that KIF2A may be a novel target in allergic asthma.

Integrative Analysis Reveals a miRNA-mRNA Regulatory Network and Potential Causative Agents in the Asthmatic Airway Epithelium.

BackgroundDuring asthma progression, the intricate molecular networks, including microRNA (miRNA) transcriptional regulation in airway epithelium, remain largely undefined. The abnormal expression of miRNAs in asthmatic airway epithelium is a recent and fast-growing area in developing diagnostic and therapeutic targets for asthma.Material and MethodsAnalyses were conducted to compare airway epithelial miRNAs and gene expression between patients with asthma and healthy subjects from three datasets (two for miRNAs expression profiles and one for gene expression profile). The interactions network between differentially expressed (DE)-miRNAs and mRNAs was further identified for functional analysis. To verify the involvement and functions of all the identified miRNAs in asthma, we constructed two cellular models of asthma. The most promising causal miRNA candidate, miR-1246, was examined in an in vitro system to explore its targets and roles in asthma pathophysiology.ResultsThrough integrative analysis, we obtained six miRNAs with 31 validated target genes in airway epithelium associated with asthma. Next, we confirmed that these miRNAs were all associated with asthma progression by in vitro functional experiments. They may participate in eosinophilic inflammation (miR-92b-3p, miR-1246, miR-197-3p, and miR-124-5p) or remodeling (miR-197-3p, miR-193a-5p, miR-1246, and miR-92b-3p). Additionally, some other non-screened valuable miRNAs were also examined and identified (miR-21-5p and miR-19b-3p), and some detected in blood correlated with the disease status. Furthermore, we found that miR-1246 could directly target POSTN and influence epithelial-to-mesenchymal transition and fibrosis in airway epithelial cells.ConclusionWe constructed a preliminary epithelial regulatory network in asthma based on six identified miRNAs and their valuable target genes. Candidate factors in the biological miRNA-mRNA network in airway epithelium may provide further information on the pathogenesis of asthma. Strikingly, among all screened miRNAs, miR-1246, which could interact with POSTN may have multifunctional effects in the course of asthma and be a promising agent for asthma treatment and molecular subtyping.

Up-regulation of ACE2, the SARS-CoV-2 receptor, in asthmatics on maintenance inhaled corticosteroids

BackgroundThe first step in SARS-CoV-2 infection is binding of the virus to angiotensin converting enzyme 2 (ACE2) on the airway epithelium. Asthma affects over 300 million people world-wide, many of whom may encounter SARS-CoV-2. Epidemiologic data suggests that asthmatics who get infected may be at increased risk of more severe disease. Our objective was to assess whether maintenance inhaled corticosteroids (ICS), a major treatment for asthma, is associated with airway ACE2 expression in asthmatics.MethodsLarge airway epithelium (LAE) of asthmatics treated with maintenance ICS (ICS+), asthmatics not treated with ICS (ICS−), and healthy controls (controls) was analyzed for expression of ACE2 and other coronavirus infection-related genes using microarrays.ResultsAs a group, there was no difference in LAE ACE2 expression in all asthmatics vs controls. In contrast, subgroup analysis demonstrated that LAE ACE2 expression was higher in asthmatics ICS+ compared to ICS‾ and ACE2 expression was higher in male ICS+ compared to female ICS+ and ICS‾ of either sex. ACE2 expression did not correlate with serum IgE, absolute eosinophil level, or change in FEV1 in response to bronchodilators in either ICS− or ICS+.ConclusionAirway ACE2 expression is increased in asthmatics on long-term treatment with ICS, an observation that should be taken into consideration when assessing the use of inhaled corticosteroids during the pandemic.

COL4A3 expression in asthmatic epithelium depends on intronic methylation and ZNF263 binding.

BackgroundReduction of COL4A3, one of the six isoforms of collagen 4, in asthmatic airways results in increased inflammation and angiogenesis, implicating it as a central part of asthma pathogenesis. However, to date, the path underlying these diminished COL4A3 levels has been elusive. This study investigated a possible mechanism underlying the reduction of COL4A3 expression.MethodsBronchial biopsies of 76 patients with asthma and 83 controls were subjected to RNA-sequencing and DNA methylation bead arrays to identify expression and methylation changes. The binding of ZNF263 was analysed by chromatin-immunoprecipitation sequencing coupled with quantitative (q)PCR. Effects of ZNF263 silencing, using small interfering RNA, on the COL4A3 expression were studied using qPCR.ResultsCOL4A3 expression was significantly reduced in bronchial biopsies compared to healthy controls, whereas DNA methylation levels at cg11797365 were increased. COL4A3 expression levels were significantly low in asthmatics without inhaled corticosteroid (ICS) use, whereas the expression was not statistically different between asthmatics using ICS and controls. Methylation levels at cg11797365 in vitro were increased upon consecutive rhinovirus infections.ConclusionOur data indicate an epigenetic modification as a contributing factor for the loss of COL4A3 expression in asthmatic airway epithelium.

Ginsenoside Rg3 ameliorates allergic airway inflammation and oxidative stress in mice

BackgroundGinsenoside Rg3, isolated from Panax ginseng, has anti-inflammatory and anti-tumor activities. It is known to reduce inflammation in acute lung injury in mice, and to reduce the expression of inflammatory cytokines and COX-2 in human asthmatic airway epithelium. In this study, we attempted to determine whether ginsenoside Rg3 inhibits airway inflammation, oxidative stress, and airway hyperresponsiveness (AHR) in the lungs of asthmatic mice. We also investigated its effects on oxidative stress and the inflammatory response in tracheal epithelial cells. MethodsAsthma symptoms were induced in female BALB/c mice sensitized with ovalbumin (OVA). Mice were divided into five groups: normal controls, OVA-induced asthmatic controls, and asthmatic mice treated with ginsenoside Rg3 or prednisolone by intraperitoneal injection. Inflammatory BEAS-2B cells (human tracheal epithelial cells) treated with ginsenoside Rg3 to investigate its effects on inflammatory cytokines and oxidative responses. ResultsGinsenoside Rg3 treatment significantly reduced eosinophil infiltration, oxidative responses, airway inflammation, and AHR in the lungs of asthmatic mice. Ginsenoside Rg3 reduced Th2 cytokine and chemokine levels in bronchoalveolar lavage fluids and lung. Inflammatory BEAS-2B cells treated with ginsenoside Rg3 reduced the eotaxin and pro-inflammatory cytokine expressions, and monocyte adherence to BEAS-2B cells was significantly reduced as a result of decreased ICAM-1 expression. Furthermore, ginsenoside Rg3 reduced the expression of reactive oxygen species in inflammatory BEAS-2B cells. ConclusionGinsenoside Rg3 is a potential immunomodulator that can ameliorate pathological features of asthma by decreasing oxidative stress and inflammation

Ku70 modulation alleviates murine allergic asthma features and restores mitochondrial function in lungs

The airway epithelium is continuously exposed to a variety of pollutants and allergens, thanks to both natural and manmade environmental pollution. With numerous protective mechanisms, the airway epithelium protects the lungs. DNA repair mechanism is one such protective response and its failure could lead to the accumulation of DNA mutations. Our lab had earlier demonstrated the dysfunctional mitochondria in airway epithelium of the asthmatic mice lungs. Here, we show that Ku70 modulation by the administration of Ku70 plasmid attenuates asthma features and reduces mitochondrial dysfunction in the lungs of allergen exposed mice. Ku70 is a key DNA repair protein with diverse roles including VDJ recombination, telomere maintenance, and maintenance of cell homeostasis. Recently, we found a reduction in Ku70 expression in asthmatic airway epithelium, and this was associated with mitochondrial dysfunction in asthmatic condition. In this study, we have shown that Ku70 over-expression in asthmatic mice attenuated airway hyperresponsiveness, airway inflammation, sub-epithelial fibrosis along with reduction in TGF-β with no effect in IL-13 levels and goblet cell metaplasia. Ku70 over-expression in asthmatic mice reduced 8-isoprostane, a marker of oxidative stress, and restored the mitochondrial function in asthmatic mice. We further found these roles of Ku70 to be independent of DNA damage as Ku70 overexpressed mice did not show any reduction in DNA tail, an index of DNA damage. Thus, our findings indicate that Ku70 can attenuate crucial features of asthma along with the restoration of mitochondrial function. This implies that Ku70 could be a therapeutic target for asthma without affecting DNA repair function.

Airway Epithelial Dysfunction in Asthma: Relevant to Epidermal Growth Factor Receptors and Airway Epithelial Cells.

Airway epithelium plays an important role as the first barrier from external pathogens, including bacteria, viruses, chemical substances, and allergic components. Airway epithelial cells also have pivotal roles as immunological coordinators of defense mechanisms to transfer signals to immunologic cells to eliminate external pathogens from airways. Impaired airway epithelium allows the pathogens to remain in the airway epithelium, which induces aberrant immunological reactions. Dysregulated functions of asthmatic airway epithelium have been reported in terms of impaired wound repair, fragile tight junctions, and excessive proliferation, leading to airway remodeling, which contributes to aberrant airway responses caused by external pathogens. To maintain airway epithelium integrity, a family of epidermal growth factor receptors (EGFR) have pivotal roles in mechanisms of cell growth, proliferation, and differentiation. There are extensive studies focusing on the relation between EGFR and asthma pathophysiology, which describe airway remodeling, airway hypermucus secretion, as well as immunological responses of airway inflammation. Furthermore, the second EGFR family member, erythroblastosis oncogene B2 (ErbB2), has been recognized to be involved with impaired wound recovery and epithelial differentiation in asthmatic airway epithelium. In this review, the roles of the EGFR family in asthmatic airway epithelium are focused on to elucidate the pathogenesis of airway epithelial dysfunction in asthma.

A Microengineered Airway Lung Chip Models Key Features of Viral-induced Exacerbation of Asthma.

Viral-induced exacerbation of asthma remains a major cause of hospitalization and mortality. New human-relevant models of the airways are urgently needed to understand how respiratory infections may trigger asthma attacks and to advance treatment development. Here, we describe a new human-relevant model of rhinovirus-induced asthma exacerbation that recapitulates viral infection of asthmatic airway epithelium and neutrophil transepithelial migration, and enables evaluation of immunomodulatory therapy. Specifically, a microengineered model of fully differentiated human mucociliary airway epithelium was stimulated with IL-13 to induce a T-helper cell type 2 asthmatic phenotype and infected with live human rhinovirus 16 (HRV16) to reproduce key features of viral-induced asthma exacerbation. We observed that the infection with HRV16 replicated key hallmarks of the cytopathology and inflammatory responses observed in human airways. Generation of a T-helper cell type 2 microenvironment through exogenous IL-13 stimulation induced features of asthmatic airways, including goblet cell hyperplasia, reduction of cilia beating frequency, and endothelial activation, but did not alter rhinovirus infectivity or replication. High-resolution kinetic analysis of secreted inflammatory markers revealed that IL-13 treatment altered IL-6, IFN-λ1, and CXCL10 secretion in response to HRV16. Neutrophil transepithelial migration was greatest when viral infection was combined with IL-13 treatment, whereas treatment with MK-7123, a CXCR2 antagonist, reduced neutrophil diapedesis in all conditions. In conclusion, our microengineered Airway Lung-Chip provides a novel human-relevant platform for exploring the complex mechanisms underlying viral-induced asthma exacerbation. Our data suggest that IL-13 may impair the hosts' ability to mount an appropriate and coordinated immune response to rhinovirus infection. We also show that the Airway Lung-Chip can be used to assess the efficacy of modulators of the immune response.