Cellular inhibitor of apoptosis-2 is a critical regulator of apoptosis in airway epithelial cells treated with asthma-related inflammatory cytokines

Multiomics Analysis Identifies BIRC3 as a Novel Glucocorticoid Response-Associated Gene

BACKGROUND

Inhaled corticosteroid (ICS) response among patients with asthma is influenced by genetics, but biologically actionable insights based on associations have not been found. Various glucocorticoid response omics datasets are available to interrogate their biological effects.

OBJECTIVE

We sought to identify functionally relevant ICS response genetic associations by integrating complementary multiomics datasets.

METHODS

Variants with p-values<10^-4 from a previous ICS response genome-wide association study were re-ranked based on integrative scores determined from: i) glucocorticoid receptor (GR)- and ii) RNA polymerase II (RNAP II)-binding regions inferred from ChIP-Seq data for three airway cell types, iii) glucocorticoid response element (GRE) motifs, iv) differentially expressed genes in response to glucocorticoid exposure according to 20 transcriptomic datasets, and v) expression quantitative trait loci (eQTLs) from GTEx. Candidate variants were tested for association with ICS response and asthma in six independent studies.

RESULTS

Four variants had significant (q-value<0.05) multiomics integrative scores. These variants were in a locus consisting of 52 variants in high LD (r²≥0.8) near GR-binding sites by the gene BIRC3. Variants were also BIRC3 eQTLs in lung, and two were within/near putative GRE motifs. BIRC3 had increased RNAP II occupancy and gene expression with glucocorticoid exposure in two ChIP-Seq and 13 transcriptomic datasets. Some BIRC3 variants in the 52-variant locus were associated (p-value<0.05) with ICS response in three independent studies and others with asthma in one study.

CONCLUSION

BIRC3 should be prioritized for further functional studies of ICS response.

CLINICAL IMPLICATION

Genetic variation near BIRC3 may influence ICS response in people with asthma.

Eosinophil Responses at the Airway Epithelial Barrier during the Early Phase of Influenza A Virus Infection in C57BL/6 Mice

Eosinophils, previously considered terminally differentiated effector cells, have multifaceted functions in tissues. We previously found that allergic mice with eosinophil-rich inflammation were protected from severe influenza and discovered specialized antiviral effector functions for eosinophils including promoting cellular immunity during influenza. In this study, we hypothesized that eosinophil responses during the early phase of influenza contribute to host protection. Using in vitro and in vivo models, we found that eosinophils were rapidly and dynamically regulated upon influenza A virus (IAV) exposure to gain migratory capabilities to traffic to lymphoid organs after pulmonary infection. Eosinophils were capable of neutralizing virus upon contact and combinations of eosinophil granule proteins reduced virus infectivity through hemagglutinin inactivation. Bi-directional crosstalk between IAV-exposed epithelial cells and eosinophils occurred after IAV infection and cross-regulation promoted barrier responses to improve antiviral defenses in airway epithelial cells. Direct interactions between eosinophils and airway epithelial cells after IAV infection prevented virus-induced cytopathology in airway epithelial cells in vitro, and eosinophil recipient IAV-infected mice also maintained normal airway epithelial cell morphology. Our data suggest that eosinophils are important in the early phase of IAV infection providing immediate protection to the epithelial barrier until adaptive immune responses are deployed during influenza.

Leukotriene D4 role in allergic asthma pathogenesis from cellular and therapeutic perspectives

Asthma is a chronic inflammatory and allergic disease that is mainly characterized by reversible airway obstruction and bronchial hyperresponsiveness. The incidence of asthma is increasing with more than 350 million people worldwide are affected. Up to now, there is no therapeutic option for asthma and most of the prescribed drugs aim to ameliorate the symptoms of the disease especially during the acute exacerbations after trigger exposure. Asthma is a heterogonous disease that involves interactions between inflammatory mediators and cellular components within the disease microenvironment including inflammatory and structural cells. Cysteinyl leukotrienes (cys-LTs) are inflammatory lipid mediators that have potent roles in asthma pathogenesis. CysLTs consisting of LTC₄, LTD₄, and LTE₄ are mainly secreted by leukocytes and act through three main G-protein coupled receptors (CysLT₁R, CysLT₂R, and CysLT₃R). LTD₄ is the most potent bronchoconstrictor which gives it the priority to be discussed in detail in this review. LTD₄ binds with high affinity to CysLT₁R and many studies showed that using CysLT₁R antagonists such as montelukast has a beneficial effect for asthmatics especially in corticosteroid refractory cases. Since asthma is a heterogeneous inflammatory disease of many cell types involved in the disease pathogenies and LTD₄ has a special role in inflammation and bronchoconstriction, this review highlights the role of LTD₄ on each cellular component in asthma and the benefits of using CysLT₁R antagonists in ameliorating LTD₄-induced effects.

microRNA-23a contributes to asthma by targeting BCL2 in airway epithelial cells and CXCL12 in fibroblasts

The deregulated cross-talk between airway epithelial cells with subepithelial fibroblasts during inflammation drives the pathogenesis of asthma. Bioinformatics analysis and luciferase activity assay suggested that B cell lymphoma-2 (BCL2) and CXC ligand 12 (CXCL12) are potential targets of miR-23a. The aim of this study was to elucidate the effect of microRNA-23a (miR-23a) on BCL2, and CXCL12 in asthma. In E3 rats, miR-23a was upregulated in lung tissues after antigen-induced pulmonary inflammation during acute and chronic inflammation. Immunohistochemistry showed downregulation of BCL2 in the epithelium and of CXCL12 in subepithelial fibroblasts and smooth muscle cells. Treatment of isolated cells with miR-23a mimic or inhibitor modified the expression of BCL2 and of CXCL12 in the expected cell type-specific manner. Moreover, in epithelial cells, interleukin-4 upregulated miR-23a expression and thereby decreased the expression of BCL2, while increasing the caspase-3 expression, which was followed by apoptosis. In fibroblasts, the expression of miR-23a was increased by thymic stromal lymphopoietin (TSLP). Consequently, the CXCL12 expression was abrogated. The phosphorylation of CREB was also downregulated by TSLP through the action of miR-23a. This study describes a novel mechanism, where miR-23a is an important cell type-specific regulator for asthma-associated airway wall remodeling parameter. Thus, miR-23a may present a potential new target for the therapy of asthma.

Airway epithelial cells exposed to wildfire smoke extract exhibit dysregulated autophagy and barrier dysfunction consistent with COPD

BACKGROUND

Individuals with respiratory disease are being increasingly exposed to wildfire smoke as populations encroach further into forested regions and climate change continues to bring higher temperatures with lower rainfall. Frequent exposures have significant potential to accelerate conditions such as chronic obstructive pulmonary disease (COPD) which is characterised by an exaggerated inflammatory response to environmental stimuli. Here we employ models of human airway epithelium exposed to wildfire smoke-extract (WFSE) to examine modulation in airway epithelial cell (AEC) survival, fragility and barrier function.

METHODS

Submerged cultures of small airway epithelial cells (SAEC) and differentiated air-liquid interface (ALI) cultures of primary bronchial AEC (bAEC) were treated for 1-24 h with 1-10% WFSE generated from plant species found in the Australian bushland. Autophagy (LC3-II and Sequestosome), apoptosis (Poly-(ADP)-Ribose Polymerase (PARP) cleavage) and tight junction proteins were measured using western blot. Barrier function was assessed via permeability of fluorescein tracers and measuring trans-epithelial electrical resistance. The production of IL-6 was assessed using ELISA.

RESULTS

Primary epithelial models exposed to WFSE exhibited a significant blockade in autophagy as evidenced by an increase in LC3-II coupled with a concomitant elevation in Sequestosome abundance. These exposures also induced significant PARP cleavage indicative of apoptotic changes. ALI cultures of bAEC treated with 5% WFSE demonstrated barrier dysfunction with significant increases in paracellular molecular permeability and ionic conductance, and a reduction in the abundance of the tight junction proteins ZO-1 and Claudin-1. These cultures also exhibited increased IL-6 secretion consistent with the aberrant and pro-inflammatory repair response observed in the COPD airways. Further, blocks in autophagy and barrier disruption were significantly elevated in response to WFSE in comparison to similar exposures with cigarette smoke-extract.

CONCLUSION

WFSE inhibits autophagic flux and induces barrier dysfunction in the airway epithelium. As autophagy is a central regulator of cellular repair, viability, and inflammation, targeting the block in autophagic flux may ameliorate the consequences of wildfire smoke-exposure for individuals with pre-existing respiratory conditions.

PI3K/mTOR dual inhibitor BEZ235 and histone deacetylase inhibitor Trichostatin A synergistically exert anti-tumor activity in breast cancer

Molecule-targeted therapy has achieved great progress in cancer therapy. Effective drug combinations are one way to enhance the therapeutic efficacy and combat resistance. Here, we determined the effect of the PI3K/mTOR dual inhibitor BEZ235 and the histone deacetylase inhibitor Trichostatin A (TSA) on human breast cancer. We demonstrated that the combination of BEZ235 and TSA results in significant synergistic growth inhibition of multiple breast cancer cell lines. Mechanistic studies revealed that the combined therapy induced apoptosis in a caspase-dependent manner, which might be related to the further depression of the PI3K/Akt/mTOR signalling pathway. Additionally, co-treatment with BEZ235 and TSA enhanced autophagic cell death by up-regulating the expression of LC3B-II and Beclin-1. The vivo tumour modelling studies revealed that BEZ235 combined with TSA blocked tumour growth without noticeable side effects. These data suggest that the combination of BEZ235 and TSA may be a new selective strategy, which may have significant clinical application in the treatment of breast cancer patients.

Polymorphisms of RAD50, IL33 and IL1RL1 are associated with atopic asthma in Chinese population

Genetic architecture of asthma remains obscure. This study aimed to investigate whether the genetic polymorphisms of CDHR3 (rs6967330), GSDMB (rs2305480), IL33 rs928413, RAD50 (rs6871536) and IL1RL1 (rs1558641) are associated with the development of atopic asthma in Chinese population. Genotype and allele frequencies were compared between 516 patients and 552 controls by Chi-square test. Patients were found to have significantly higher allele G of rs928413 and allele C of rs6871536 (9.5% vs 6.2%, P = 0.004 for rs928413; 26.1% vs 19.9%, P < 0.001 for rs6871536). Besides, patients were found to have significantly lower frequency of allele A of rs1558641 (17.2% vs 21.7%, P = 0.007). This is the first study validating that IL33, IL1R1, and RAD50 genes are associated with the risk of asthma in Chinese population.

TLR response pathways in NuLi-1 cells and primary human nasal epithelial cells

The present study describes and compares functional properties of Nuli-1 cells and primary human nasal epithelial cells (HNEC) including TLR expression and function. Differences in gene expression were identified for non-TLR genes that play a role in TLR response pathways. However, experiments comparing TLR gene expression for both Nuli-1 cells and HNECs indicated conserved expression in both cell types. Stimulation of the two cell types resulted in a conserved response to TLR3 agonists, but in differences in response to agonists for TLR5 and TLR6/2. HNECs were much more susceptible to infection with Staphylococcus aureus than NuLi-1 cells. Furthermore, when cultured at air-liquid interface (ALI), NuLi-1 cells possessed much lower trans-epithelial resistance than primary HNEC and did not exhibit maintenance of cell morphology or mucous production which was observed in HNECs. Nor did they produce the characteristic interconnecting pattern of tight junction complexes at the apicolateral margin of adjacent cells. Caution should therefore be exercised when selecting cell lines for immunological studies and a thorough screen of properties relevant to the study should always be carried out prior to commencement.

Glucocorticoid genes and the developmental origins of asthma susceptibility and treatment response

Antenatal corticosteroids enhance lung maturation. However, the importance of glucocorticoid genes on early lung development, asthma susceptibility, and treatment response remains unknown. We investigated whether glucocorticoid genes are important during lung development and their role in asthma susceptibility and treatment response. We identified genes that were differentially expressed by corticosteroids in two of three genomic datasets: lymphoblastoid cell lines of participants in the Childhood Asthma Management Program, a glucocorticoid chromatin immunoprecipitation/RNA sequencing experiment, or a murine model; these genes made up the glucocorticoid gene set (GCGS). Using gene expression profiles from 38 human fetal lungs and C57BL/6J murine fetal lungs, we identified developmental genes that were in the top 5% of genes contributing to the top three principal components (PCs) most highly associated with post-conceptional age. Glucocorticoid genes that were enriched in this set of developmental genes were then included in the developmental glucocorticoid gene set (DGGS). We then investigated whether glucocorticoid genes are important during lung development, and their role in asthma susceptibility and treatment response. A total of 232 genes were included in the GCGS. Analysis of gene expression demonstrated that glucocorticoid genes were enriched in lung development (P = 7.02 × 10(-26)). The developmental GCGS was enriched for genes that were differentially expressed between subjects with asthma and control subjects (P = 4.26 × 10(-3)) and were enriched after treatment of subjects with asthma with inhaled corticosteroids (P < 2.72 × 10(-4)). Our results show that glucocorticoid genes are overrepresented among genes implicated in fetal lung development. These genes influence asthma susceptibility and treatment response, suggesting their involvement in the early ontogeny of asthma.

Obesity, metabolic syndrome, and airway disease: a bioenergetic problem?

Multiple studies have determined that obesity increases asthma risk or severity. Metabolic changes of obesity, such as diabetes or insulin resistance, are associated with asthma and poorer lung function. Insulin resistance is also found to increase asthma risk independent of body mass. Conversely, asthma is associated with abnormal glucose and lipid metabolism, insulin resistance, and obesity. Here we review our current understanding of how dietary and lifestyle factors lead to changes in mitochondrial metabolism and cellular bioenergetics, inducing various components of the cardiometabolic syndrome and airway disease.