Single-cell analysis reveals alterations in cellular composition and cell-cell communication associated with airway inflammation and remodeling in asthma.

BACKGROUND: Asthma is a heterogeneous disease characterized by airway inflammation and remodeling, whose pathogenetic complexity was associated with abnormal responses of various cell types in the lung. The specific interactions between immune and stromal cells, crucial for asthma pathogenesis, remain unclear. This study aims to determine the key cell types and their pathological mechanisms in asthma through single-cell RNA sequencing (scRNA-seq). METHODS: A 16-week mouse model of house dust mite (HDM) induced asthma (n = 3) and controls (n = 3) were profiled with scRNA-seq. The cellular composition and gene expression profiles were assessed by bioinformatic analyses, including cell enrichment analysis, trajectory analysis, and Gene Set Enrichment Analysis. Cell-cell communication analysis was employed to investigate the ligand-receptor interactions. RESULTS: The asthma model results in airway inflammation coupled with airway remodeling and hyperresponsiveness. Single-cell analysis revealed notable changes in cell compositions and heterogeneities associated with airway inflammation and remodeling. GdT17 cells were identified to be a primary cellular source of IL-17, related to inflammatory exacerbation, while a subpopulation of alveolar macrophages exhibited numerous significantly up-regulated genes involved in multiple pathways related to neutrophil activities in asthma. A distinct fibroblast subpopulation, marked by elevated expression levels of numerous contractile genes and their regulators, was observed in increased airway smooth muscle layer by immunofluorescence analysis. Asthmatic stromal-immune cell communication significantly strengthened, particularly involving GdT17 cells, and macrophages interacting with fibroblasts. CXCL12/CXCR4 signaling was remarkedly up-regulated in asthma, predominantly bridging the interaction between fibroblasts and immune cell populations. Fibroblasts and macrophages could jointly interact with various immune cell subpopulations via the CCL8/CCR2 signaling. In particular, fibroblast-macrophage cell circuits played a crucial role in the development of airway inflammation and remodeling through IL1B paracrine signaling. CONCLUSIONS: Our study established a mouse model of asthma that recapitulated key pathological features of asthma. ScRNA-seq analysis revealed the cellular landscape, highlighting key pathological cell populations associated with asthma pathogenesis. Cell-cell communication analysis identified the crucial ligand-receptor interactions contributing to airway inflammation and remodeling. Our findings emphasized the significance of cell-cell communication in bridging the possible causality between airway inflammation and remodeling, providing valuable hints for therapeutic strategies for asthma.

Estrogen receptors differentially modifies lamellipodial and focal adhesion dynamics in airway smooth muscle cell migration.

Sex-steroid signaling, especially estrogen, has a paradoxical impact on regulating airway remodeling. In our previous studies, we demonstrated differential effects of 17ß-estradiol (E2) towards estrogen receptors (ERs: α and ß) in regulating airway smooth muscle (ASM) cell proliferation and extracellular matrix (ECM) production. However, the role of ERs and their signaling on ASM migration is still unexplored. In this study, we examined how ERα versus ERß affects the mitogen (Platelet-derived growth factor, PDGF)-induced human ASM cell migration as well as the underlying mechanisms involved. We used Lionheart-FX automated microscopy and transwell assays to measure cell migration and found that activating specific ERs had differential effects on PDGF-induced ASM cell migration. Pharmacological activation of ERß or shRNA mediated knockdown of ERα and specific activation of ERß blunted PDGF-induced cell migration. Furthermore, specific ERß activation showed inhibition of actin polymerization by reducing the F/G-actin ratio. Using Zeiss confocal microscopy coupled with three-dimensional algorithmic ZEN-image analysis showed an ERß-mediated reduction in PDGF-induced expressions of neural Wiskott-Aldrich syndrome protein (N-WASP) and actin-related proteins-2/3 (Arp2/3) complex, thereby inhibiting actin-branching and lamellipodia. In addition, ERß activation also reduces the clustering of actin-binding proteins (vinculin and paxillin) at the leading edge of ASM cells. However, cells treated with E2 or ERα agonists do not show significant changes in actin/lamellipodial dynamics. Overall, these findings unveil the significance of ERß activation in regulating lamellipodial and focal adhesion dynamics to regulate ASM cell migration and could be a novel target to blunt airway remodeling.

Airway smooth muscle in contractility and remodeling of asthma: potential drug target mechanisms.

INTRODUCTION: Asthma is characterized by enhanced airway contractility and remodeling where airway smooth muscle (ASM) plays a key role, modulated by inflammation. Understanding the mechanisms by which ASM contributes to these features of asthma is essential for the development of novel asthma therapies. AREAS COVERED: Inflammation in asthma contributes to a multitude of changes within ASM including enhanced airway contractility, proliferation, and fibrosis. Altered intracellular calcium ([Ca2+]i) regulation or Ca2+ sensitization contributes to airway hyperreactivity. Increased airway wall thickness from ASM proliferation and fibrosis contributes to structural changes seen with asthma. EXPERT OPINION: ASM plays a significant role in multiple features of asthma. Increased ASM contractility contributes to hyperresponsiveness, while altered ASM proliferation and extracellular matrix production promote airway remodeling both influenced by inflammation of asthma and conversely even influencing the local inflammatory milieu. While standard therapies such as corticosteroids or biologics target inflammation, cytokines, or their receptors to alleviate asthma symptoms, these approaches do not address the underlying contribution of ASM to hyperresponsiveness and particularly remodeling. Therefore, novel therapies for asthma need to target abnormal contractility mechanisms in ASM and/or the contribution of ASM to remodeling, particularly in asthmatics resistant to current therapies.

Differential remodeling in small and large murine airways revealed by novel whole lung airway analysis.

Airway remodeling occurs in chronic asthma leading to increased airway smooth muscle (ASM) mass and extracellular matrix (ECM) deposition. Although extensively studied in murine airways, studies report only selected larger airways at one time-point meaning the spatial distribution and resolution of remodeling are poorly understood. Here we use a new method allowing comprehensive assessment of the spatial and temporal changes in ASM, ECM, and epithelium in large numbers of murine airways after allergen challenge. Using image processing to analyze 20-50 airways per mouse from a whole lung section revealed increases in ASM and ECM after allergen challenge were greater in small and large rather than intermediate airways. ASM predominantly accumulated adjacent to the basement membrane, whereas ECM was distributed across the airway wall. Epithelial hyperplasia was most marked in small and intermediate airways. After challenge, ASM changes resolved over 7 days, whereas ECM and epithelial changes persisted. The new method suggests large and small airways remodel differently, and the long-term consequences of airway inflammation may depend more on ECM and epithelial changes than ASM. The improved quantity and quality of unbiased data provided by the method reveals important spatial differences in remodeling and could set new analysis standards for murine asthma models.

HRCT quantitative analysis of airway remodeling and airway trapping in the small airway asthma phenotype and its correlation with pulmonary function.

OBJECTIVES: We aimed to explore whether large airway remodeling and small airway structural changes exist in subjects with small airway asthma phenotype and to evaluate the relationships between quantitative high-resolution computed tomography (qHRCT) parameters and lung function. METHODS: We enrolled 15 subjects with small airway asthma phenotype and 18 healthy controls. The two groups were matched by age, sex and body square area (BSA) with propensity score matching (PSM). Pulmonary function and qHRCT parameters [wall thickness (WT), wall area (WA), lumen area (LA), wall area percentage (WA%) of the 4th-6th generations in the right upper lobe apical segmental bronchus (RB1), adjusted by BSA, WT/BSA, WA/BSA, and LA/BSA, relative volume change -860 HU to -950 HU (RVC-860 to -950) and the expiration to inspiration ratio of mean lung density (MLDE/I)) were compared between the groups. Correlation analysis was employed to assess the relationship between qHRCT parameters and pulmonary function. RESULTS: The small airway asthma phenotype had significantly higher WA%, RVC-860 to -950 and MLDE/I and lower LA/BSA than the healthy control. Additionally, we found moderate to strong correlations between impulse oscillation (IOS) indices and WA6% and WT6/BSA. No significant correlation was found between bronchial parameters and air trapping parameters (p > 0.05). CONCLUSIONS: Combining physiological tests with imaging approaches can lead to better evaluation of small airway disfunction (SAD) in asthmatic patients. Additionally, despite nonexistent airflow obstruction in patients with small airway asthma phenotype, large airway remodeling and small airway structural changes may appear simultaneously in the early stage of disease.

Airway epithelial ITGB4 deficiency induces airway remodeling in a mouse model.

BACKGROUND: Airway epithelial cells (AECs) with impaired barrier function contribute to airway remodeling through the activation of epithelial-mesenchymal trophic units (EMTUs). Although the decreased expression of ITGB4 in AECs is implicated in the pathogenesis of asthma, how ITGB4 deficiency impacts airway remodeling remains obscure. OBJECTIVE: This study aims to determine the effect of epithelial ITGB4 deficiency on the barrier function of AECs, asthma susceptibility, airway remodeling, and EMTU activation. METHODS: AEC-specific ITGB4 conditional knockout mice (ITGB4-/-) were generated and an asthma model was employed by the sensitization and challenge of house dust mite (HDM). EMTU activation-related growth factors were examined in ITGB4-silenced primary human bronchial epithelial cells of healthy subjects after HDM stimulation. Dexamethasone, the inhibitors of JNK phosphorylation or FGF2 were administered for the identification of the molecular mechanisms of airway remodeling in HDM-exposed ITGB4-/- mice. RESULTS: ITGB4 deficiency in AECs enhanced asthma susceptibility and airway remodeling by disrupting airway epithelial barrier function. Aggravated airway remodeling in HDM-exposed ITGB4-/- mice was induced through the enhanced activation of EMTU mediated by Src homology domain 2-containing protein tyrosine phosphatase 2/c-Jun N-terminal kinase/Jun N-terminal kinase-dependent transcription factor/FGF2 (SHP2/JNK/c-Jun/FGF2) signaling pathway, which was partially independent of airway inflammation. Both JNK and FGF2 inhibitors significantly inhibited the aggravated airway remodeling and EMTU activation in HDM-exposed ITGB4-/- mice. CONCLUSIONS: Airway epithelial ITGB4 deficiency induces airway remodeling in a mouse model of asthma through enhanced EMTU activation that is regulated by the SHP2/JNK/c-Jun/FGF2 pathway.

The Regulation Mechanism of MUC5AC Secretion in Airway of Obese Asthma.

The purpose of this study was to establish a rat asthma model and extract MUC5AC to explore the mechanism of mucin 5AC (MUC5AC) signaling pathway regulating the function of asthmatic airway smooth muscle cells (ASMC) and participating in asthmatic airway remodeling. Western blot was used to detect ß-catenin (ß-catenin), glycogen synthase kinase-3ß (GSK-3ß), proto-oncogene MUC5AC and cyclin D1 (cyclin D1) in MUC5AC of asthmatic and normal groups. After inhibiting the interaction between ß-catenin and transcription cofactor p300 / CBP in ASMC of the asthma group and control group, the cell viability and cycle changes of ASMC were detected by the CCK-8 method and flow cytometry. After inhibiting the activity of P38 mitogen-activated protein kinase (MAPK), the protein expression changes of c-Myc and cyclin D1 were detected by Western blot. Results showed that comprehensive HE staining results of lung tissue sections indicate that the experimental rat model of asthma airway remodeling was successfully established. Compared with the control group, 100 fxmol and L1 Efaroxan promoted insulin secretion (P <0.01), and administration of the MUC5AC antagonist KU14R significantly inhibited the effect of MUC5AC.Western blot showed that the protein expression levels of ß-catenin, c-Myc and cyclin D1 in ASMC of the obese asthma group were significantly higher than those of the control group (P <0.05), while the protein expression level of GSK-3ß was lower than Control group (P <0.05). After inhibiting the interaction between ß-catenin and p300 / CBP, the decrease in cell viability and the degree of cell cycle change of ASMC in the asthma group were more obvious than those in the control group (P <0.05). After inhibiting the activity of P38 MAPK, the expressions of the target proteins c-Myc and cyclin D1 in the MUC5AC signaling pathway in ASMC model rats and control rats were down-regulated, and the difference was statistically significant (P <0.05). The conclusion was that the Wnt/ß-catenin signaling pathway can regulate the proliferation and differentiation of ASMC by up-regulating the expression level of cMyc. Cyclin D1 interacts with the MAPK signaling pathway, thereby affecting the function of ASMC and participating in asthma airway remodeling.

Cellular senescence is increased in airway smooth muscle cells of elderly persons with asthma.

Senescent cells can drive age-related tissue dysfunction partially via a senescence-associated secretory phenotype (SASP) involving proinflammatory and profibrotic factors. Cellular senescence has been associated with a structural and functional decline during normal lung aging and age-related diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Asthma in the elderly (AIE) represents a major healthcare burden. AIE is associated with bronchial airway hyperresponsiveness and remodeling, which involves increased cell proliferation and higher rates of fibrosis, and resistant to standard therapy. Airway smooth muscle (ASM) cells play a major role in asthma such as remodeling via modulation of inflammation and the extracellular matrix (ECM) environment. Whether senescent ASM cells accumulate in AIE and contribute to airway structural or functional changes is unknown. Lung tissues from elderly persons with asthma showed greater airway fibrosis compared with age-matched elderly persons with nonasthma and young age controls. Lung tissue or isolated ASM cells from elderly persons with asthma showed increased expression of multiple senescent markers including phospho-p53, p21, telomere-associated foci (TAF), as well as multiple SASP components. Senescence and SASP components were also increased with aging per se. These data highlight the presence of cellular senescence in AIE that may contribute to airway remodeling.

Effect of the BMPR-II-SMAD3/MRTF pathway on proliferation and migration of ASMCs and the mechanism in asthma.

BACKGROUND: A variety of smooth muscle-specific genes and proteins, including SMAD3, BMPR-II, and MRTF, are involved in airway remodeling in asthma. As a receptor of bone morphogenetic protein (BMP) signaling, BMPR-II has important roles in airway remodeling in asthma. However, the underlying mechanism of BMPR-II in airway smooth muscle cells (ASMCs) in asthma remains incomplete. METHODS: Wistar rats were intraperitoneally injected with ovalbumin antigen suspension and aluminium hydroxide and, stimulated with ovalbumin nebulized inhalation to constructed asthma model. Primary ASMCs were isolated with collagenase I and identified by testing the α-SMA expression. Quantitative polymerase chain reaction (qPCR) and western blot assay were employed to detect the gene expression. CCK8, Transwell and Fluo-4 A assays were introduced to measure the cell viability, migration and intracellular Ca2+. Co-Immunoprecipitation (Co-IP) assay was applied to test the interaction among proteins. RESULTS: First, we observed significant increases in BMPR-II in asthmatic rat model and ASMCs at both the mRNA and protein levels. Second, we observed that silencing of siBMPR-II inhibited proliferation, migratory capacity and intracellular Ca2+ concentration in ASMCs. Furthermore, our study demonstrated that siBMPR-II inhibited the Smad3 expression and overexpression promoted the bioactivity of ASMCs. In addition, this study showed that p-Smad3 could interacted with MRTF and siMRTF inhibits the bioactivity of ASMCs. Finally, our results revealed BMPR-II-SMAD3/MRTF pathway affected the bioactivity of ASMCs. CONCLUSIONS: This study indicates that the BMPR-II-SMAD3/MRTF signaling pathway is involved in the process of ASMCs remodeling, providing novel avenues for the identification of new therapeutic modalities.

Characterization of Immunopathology and Small Airway Remodeling in Constrictive Bronchiolitis.

Rationale: Constrictive bronchiolitis (ConB) is a relatively rare and understudied form of lung disease whose underlying immunopathology remains incompletely defined. Objectives: Our objectives were to quantify specific pathological features that differentiate ConB from other diseases that affect the small airways and to investigate the underlying immune and inflammatory phenotype present in ConB. Methods: We performed a comparative histomorphometric analysis of small airways in lung biopsy samples collected from 50 soldiers with postdeployment ConB, 8 patients with sporadic ConB, 55 patients with chronic obstructive pulmonary disease, and 25 nondiseased control subjects. We measured immune and inflammatory gene expression in lung tissue using the NanoString nCounter Immunology Panel from six control subjects, six soldiers with ConB, and six patients with sporadic ConB. Measurements and Main Results: Compared with control subjects, we found shared pathological changes in small airways from soldiers with postdeployment ConB and patients with sporadic ConB, including increased thickness of the smooth muscle layer, increased collagen deposition in the subepithelium, and lymphocyte infiltration. Using principal-component analysis, we showed that ConB pathology was clearly separable both from control lungs and from small airway disease associated with chronic obstructive pulmonary disease. NanoString gene expression analysis from lung tissue revealed T-cell activation in both groups of patients with ConB with upregulation of proinflammatory pathways, including cytokine-cytokine receptor interactions, NF-κB (nuclear factor-κB) signaling, TLR (Toll-like receptor) signaling, T-cell receptor signaling, and antigen processing and presentation. Conclusions: These findings indicate shared immunopathology among different forms of ConB and suggest that an ongoing T-helper cell type 1-type adaptive immune response underlies airway wall remodeling in ConB.

TRIM33 Modulates Inflammation and Airway Remodeling of PDGF-BB-Induced Airway Smooth-Muscle Cells by the Wnt/ß-Catenin Pathway.

Asthma is a chronic airway disease involving airway inflammation and remodeling. Studies showed that tripartite motif-containing protein 33 (TRIM33) regulated natural immunity, inflammation, and pulmonary fibrosis. However, the role and regulatory mechanism of TRIM33 in children's asthma are unclear. In this study, the TRIM33 expressions in serum samples and platelet-derived growth factor BB (PDGF-BB)-induced airway smooth-muscle cells (ASMCs) were evaluated. A gain-of-function experiment was performed, and cell proliferation and migration were detected using CCK-8 and wound healing assays. Besides, the protein levels of EMT biomarkers and airway-remodeling markers were determined by Western blot assay. ELISA analyzed the contents of IL-1ß, IL-6, and TNF-α in the supernatant. The modulation of Smad4 expression and subsequent activation of Wnt/ß-catenin by TRIM33 were also assessed. We found that TRIM33 was downregulated in the serum from children who were asthma patients and PDGF-BB-induced ASMCs. TRIM33 overexpression showed decrease of PDGF-BB-induced ASMC proliferation and migration. Moreover, the augment of TRIM33 reduced the PDGF-BB-induced cell EMT and airway-remodeling marker levels and suppressed the secretions of inflammatory cytokines in PDGF-BB-induced ASMCs. Additionally, TRIM33 overexpression inhibited activation of Wnt/ß-catenin via reducing Smad4 expression to regulate asthma inflammation and airway remodeling. All in all, our study revealed that TRIM33 expression was downregulated in children who were asthma patients and PDGF-BB-induced ASMCs. TRIM33 modulated PDGF-BB-induced inflammation and airway remodeling of ASMCs by the Wnt/ß-catenin pathway via regulating Smad4, which may provide a new treatment direction for asthma.

Roles of sirtuin family members in chronic obstructive pulmonary disease.

The globally increasing annual incidence of chronic obstructive pulmonary disease (COPD), a common chronic disease, poses a serious risk to public health. Although the exact mechanism underlying the pathogenesis of COPD remains unclear, a large number of studies have shown that its pathophysiology and disease course are closely related to oxidative stress, inflammation, apoptosis, autophagy, and aging. The key players involved in COPD include the sirtuin family of NAD-dependent deacetylases that comprise seven members (SIRT1-7) in mammals. Sirtuins play an important role in metabolic diseases, cell cycle control, proliferation, apoptosis, and senescence. Owing to differences in subcellular localization, sirtuins exhibit anisotropy. In this narrative review, we discuss the roles and molecular pathways of each member of the sirtuin family involved in COPD to provide novel insights into the prevention and treatment of COPD and how sirtuins may serve as adjuvants for COPD treatment.

Lysyl oxidase like 2 is increased in asthma and contributes to asthmatic airway remodelling.

BACKGROUND: Airway smooth muscle (ASM) cells are fundamental to asthma pathogenesis, influencing bronchoconstriction, airway hyperresponsiveness and airway remodelling. The extracellular matrix (ECM) can influence tissue remodelling pathways; however, to date no study has investigated the effect of ASM ECM stiffness and cross-linking on the development of asthmatic airway remodelling. We hypothesised that transforming growth factor-ß (TGF-ß) activation by ASM cells is influenced by ECM in asthma and sought to investigate the mechanisms involved. METHODS: This study combines in vitro and in vivo approaches: human ASM cells were used in vitro to investigate basal TGF-ß activation and expression of ECM cross-linking enzymes. Human bronchial biopsies from asthmatic and nonasthmatic donors were used to confirm lysyl oxidase like 2 (LOXL2) expression in ASM. A chronic ovalbumin (OVA) model of asthma was used to study the effect of LOXL2 inhibition on airway remodelling. RESULTS: We found that asthmatic ASM cells activated more TGF-ß basally than nonasthmatic controls and that diseased cell-derived ECM influences levels of TGF-ß activated. Our data demonstrate that the ECM cross-linking enzyme LOXL2 is increased in asthmatic ASM cells and in bronchial biopsies. Crucially, we show that LOXL2 inhibition reduces ECM stiffness and TGF-ß activation in vitro, and can reduce subepithelial collagen deposition and ASM thickness, two features of airway remodelling, in an OVA mouse model of asthma. CONCLUSION: These data are the first to highlight a role for LOXL2 in the development of asthmatic airway remodelling and suggest that LOXL2 inhibition warrants further investigation as a potential therapy to reduce remodelling of the airways in severe asthma.

FERMT3 mediates cigarette smoke-induced epithelial-mesenchymal transition through Wnt/ß-catenin signaling.

BACKGROUND: Cigarette smoking is a major risk factor for chronic obstructive pulmonary disease (COPD) and lung cancer. Epithelial-mesenchymal transition (EMT) is an essential pathophysiological process in COPD and plays an important role in airway remodeling, fibrosis, and malignant transformation of COPD. Previous studies have indicated FERMT3 is downregulated and plays a tumor-suppressive role in lung cancer. However, the role of FERMT3 in COPD, including EMT, has not yet been investigated. METHODS: The present study aimed to explore the potential role of FERMT3 in COPD and its underlying molecular mechanisms. Three GEO datasets were utilized to analyse FERMT3 gene expression profiles in COPD. We then established EMT animal models and cell models through cigarette smoke (CS) or cigarette smoke extract (CSE) exposure to detect the expression of FERMT3 and EMT markers. RT-PCR, western blot, immunohistochemical, cell migration, and cell cycle were employed to investigate the potential regulatory effect of FERMT3 in CSE-induced EMT. RESULTS: Based on Gene Expression Omnibus (GEO) data set analysis, FERMT3 expression in bronchoalveolar lavage fluid was lower in COPD smokers than in non-smokers or smokers. Moreover, FERMT3 expression was significantly down-regulated in lung tissues of COPD GOLD 4 patients compared with the control group. Cigarette smoke exposure reduced the FERMT3 expression and induces EMT both in vivo and in vitro. The results showed that overexpression of FERMT3 could inhibit EMT induced by CSE in A549 cells. Furthermore, the CSE-induced cell migration and cell cycle progression were reversed by FERMT3 overexpression. Mechanistically, our study showed that overexpression of FERMT3 inhibited CSE-induced EMT through the Wnt/ß-catenin signaling. CONCLUSIONS: In summary, these data suggest FERMT3 regulates cigarette smoke-induced epithelial-mesenchymal transition through Wnt/ß-catenin signaling. These findings indicated that FERMT3 was correlated with the development of COPD and may serve as a potential target for both COPD and lung cancer.

Syndecan-1 Amplifies Ovalbumin-Induced Airway Remodeling by Strengthening TGFß1/Smad3 Action.

Syndecan-1 (SDC-1) is a transmembrane proteoglycan of heparin sulfate that can regulate various cell signal transduction pathways in the airway epithelial cells and fibroblasts. Airway epithelial cells and human bronchial fibroblasts are crucial in airway remodeling. However, the importance of SDC-1 in the remodeling of asthmatic airways has not been confirmed yet. The present study was the first to uncover SDC-1 overexpression in the airways of humans and mice with chronic asthma. This study also validated that an increase in SDC-1 expression was correlated with TGFß1/Smad3-mediated airway remodeling in vivo and in vitro. A small interfering RNA targeting SDC-1 (SDC-1 siRNA) and homo-SDC-1 in pcDNA3.1 (pc-SDC-1) was designed to assess the effects of SDC-1 on TGFß1/Smad3-mediated collagen I expression in Beas-2B (airway epithelial cells) and HLF-1 (fibroblasts) cells. Downregulation of the SDC-1 expression by SDC-1 siRNA remarkably attenuated TGFß1-induced p-Smad3 levels and collagen I expression in Beas-2B and HLF-1 cells. In addition, SDC-1 overexpression with pc-SDC-1 enhanced TGFß1-induced p-Smad3 level and collagen I expression in Beas-2B and HLF-1 cells. Furthermore, the levels of p-Smad3 and collagen I induced by TGFß1 were slightly increased after the addition of the recombinant human SDC-1 protein to Beas-2B and HLF-1 cells. These findings in vitro were also confirmed in a mouse model. A short hairpin RNA targeting SDC-1 (SDC-1 shRNA) to interfere with SDC-1 expression considerably reduced the levels of p-Smad3 and remodeling protein (α-SMA, collagen I) in the airways induced by ovalbumin (OVA). Similarly, OVA-induced p-Smad3 and remodeling protein levels in airways increased after mice inhalation with the recombinant mouse SDC-1 protein. These results suggested that SDC-1 of airway epithelial cells and fibroblasts plays a key role in the development of airway remodeling in OVA-induced chronic asthma.

TIPE2 inhibits PDGF-BB-induced phenotype switching in airway smooth muscle cells through the PI3K/Akt signaling pathway.

BACKGROUND: Childhood asthma is a common respiratory disease characterized by airway inflammation. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) has been found to be involved in the progression of asthma. This study aimed to explore the role of TIPE2 in the regulation of airway smooth muscle cells (ASMCs), which are one of the main effector cells in the development of asthma. MATERIALS AND METHODS: ASMCs were transfected with pcDNA3.0-TIPE2 or si-TIPE2 for 48 h and then treated with platelet-derived growth factor (PDGF)-BB. Cell proliferation of ASMCs was measured using the MTT assay. Cell migration of ASMCs was determined by a transwell assay. The mRNA expression levels of calponin and smooth muscle protein 22α (SM22α) were measured using qRT-PCR. The levels of TIPE2, calponin, SM22α, PI3K, p-PI3K, Akt, and p-Akt were detected by Western blotting. RESULTS: Our results showed that PDGF-BB treatment significantly reduced TIPE2 expression at both the mRNA and protein levels in ASMCs. Overexpression of TIPE2 inhibited PDGF-BB-induced ASMC proliferation and migration. In addition, overexpression of TIPE2 increased the expression of calponin and SM22α in PDGF-BB-stimulated ASMCs. However, an opposite effect was observed with TIPE2 knockdown. Furthermore, TIPE2 overexpression blocked PDGF-BB-induced phosphorylation of PI3K and Akt, whereas the expression of p-PI3K and p-Akt were aggravated by TIPE2 knockdown. Additionally, the effects of TIPE2 overexpression and TIPE2 knockdown were altered by IGF-1 and LY294002 treatments, respectively. CONCLUSIONS: Our findings demonstrate that TIPE2 inhibits PDGF-BB-induced ASMC proliferation, migration, and phenotype switching via the PI3K/Akt signaling pathway. Thus, TIPE2 may be a potential therapeutic target for the treatment of asthma.

Linking Fibrotic Remodeling and Ultrastructural Alterations of Alveolar Epithelial Cells after Deletion of Nedd4-2.

Our previous study showed that in adult mice, conditional Nedd4-2-deficiency in club and alveolar epithelial type II (AE2) cells results in impaired mucociliary clearance, accumulation of Muc5b and progressive, terminal pulmonary fibrosis within 16 weeks. In the present study, we investigated ultrastructural alterations of the alveolar epithelium in relation to interstitial remodeling in alveolar septa as a function of disease progression. Two, eight and twelve weeks after induction of Nedd4-2 knockout, lungs were fixed and subjected to design-based stereological investigation at the light and electron microscopic level. Quantitative data did not show any abnormalities until 8 weeks compared to controls. At 12 weeks, however, volume of septal wall tissue increased while volume of acinar airspace and alveolar surface area significantly decreased. Volume and surface area of alveolar epithelial type I cells were reduced, which could not be compensated by a corresponding increase of AE2 cells. The volume of collagen fibrils in septal walls increased and was linked with an increase in blood-gas barrier thickness. A high correlation between parameters reflecting interstitial remodeling and abnormal AE2 cell ultrastructure could be established. Taken together, abnormal regeneration of the alveolar epithelium is correlated with interstitial septal wall remodeling.

Family with sequence similarity 13 member A mediates TGF-ß1-induced EMT in small airway epithelium of patients with chronic obstructive pulmonary disease.

BACKGROUND: To explore the role of family with sequence similarity 13 member A (FAM13A) in TGF-ß1-induced EMT in the small airway epithelium of patients with chronic obstructive pulmonary disease (COPD). METHODS: Small airway wall thickness and protein levels of airway remodeling markers, EMT markers, TGF-ß1, and FAM13A were measured in lung tissue samples from COPD and non-COPD patients. The correlations of FAM13A expression with COPD severity and EMT marker expression were evaluated. Gain- and loss-of-function assays were performed to explore the functions of FAM13A in cell proliferation, motility, and TGF-ß1-induced EMT marker alterations in human bronchial epithelial cell line BEAS-2B. RESULTS: Independent of smoking status, lung tissue samples from COPD patients exhibited significantly increased small airway thickness and collagen fiber deposition, along with enhanced protein levels of remodeling markers (collagen I, fibronectin, and MMP-9), mesenchymal markers (α-SMA, vimentin, and N-cadherin), TGF-ß1, and FAM13A, compared with those from non-COPD patients. FAM13A expression negatively correlated with FEV1% and PO2 in COPD patients. In small airway epithelium, FAM13A expression negatively correlated with E-cadherin protein levels and positively correlated with vimentin protein levels. In BEAS-2B cells, TGF-ß1 dose-dependently upregulated FAM13A protein levels. FAM13A overexpression significantly promoted cell proliferation and motility in BEAS-2B cells, whereas FAM13A silencing showed contrasting results. Furthermore, FAM13A knockdown partially reversed TGF-ß1-induced EMT marker protein alterations in BEAS-2B cells. CONCLUSIONS: FAM13A upregulation is associated with TGF-ß1-induced EMT in the small airway epithelium of COPD patients independent of smoking status, serving as a potential therapeutic target for anti-EMT therapy in COPD.

Efficacy of budesonide/glycopyrronium/formoterol metered dose inhaler in patients with COPD: post-hoc analysis from the KRONOS study excluding patients with airway reversibility and high eosinophil counts.

BACKGROUND: In the Phase III KRONOS study, triple therapy with budesonide/glycopyrronium/formoterol fumarate metered dose inhaler (BGF MDI) was shown to reduce exacerbations and improve lung function versus glycopyrronium/formoterol fumarate dihydrate (GFF) MDI in patients with moderate-to-very severe chronic obstructive pulmonary disease (COPD). However, whether the benefits related to the ICS component of BGF are driven by patients with high blood eosinophil counts (EOS) and/or airway reversibility has not been previously studied. METHODS: KRONOS was a Phase III, double-blind, parallel-group, multicenter, randomized, controlled study of patients with moderate-to-very-severe COPD. Patients were randomized 2:2:1:1 to receive BGF 320/14.4/10 µg, GFF 14.4/10 µg, budesonide/formoterol fumarate dihydrate (BFF) MDI 320/10 µg via a single Aerosphere inhaler, or open-label budesonide/formoterol fumarate dihydrate dry powder inhaler 400/12 µg (BUD/FORM DPI; Symbicort Turbuhaler) twice-daily for 24 weeks. Efficacy outcomes included in this post-hoc analysis were change from baseline in morning pre-dose trough FEV1 over weeks 12-24 and the rate of moderate-to-severe and severe COPD exacerbations. Adverse events in the non-reversible subgroup are also reported. RESULTS: Of 1896 patients analyzed, 948 (50%) were non-reversible and had EOS < 300 cells/mm3. In this group, BGF significantly improved morning pre-dose trough FEV1 versus BFF and BUD/FORM (least squares mean treatment difference, 95% confidence interval [CI] 69 mL [39, 99], unadjusted p < 0.0001 and 51 mL [20, 81], unadjusted p = 0.0011, respectively) and was comparable to GFF. BGF also significantly reduced annual moderate-to-severe exacerbation rates versus GFF (rate ratio [95% CI] 0.53 [0.37, 0.76], unadjusted p = 0.0005), with numerical reductions observed versus BFF and BUD/FORM. These results were similar for the overall study population. Safety findings were generally similar between non-reversible patients with EOS < 300 cells/mm3 and the overall population. CONCLUSIONS: In patients with moderate-to-very-severe COPD without airway reversibility and EOS < 300 cells/mm3, BGF significantly improved morning pre-dose trough FEV1 versus BFF and BUD/FORM and significantly reduced the rate of moderate-to-severe exacerbations versus GFF. These findings demonstrate that BGF can provide benefits for a broad range of patients with COPD, and that the overall findings of the KRONOS primary analysis were not driven by patients with reversible airflow obstruction or high eosinophil counts. Trial registration ClinicalTrials.gov, NCT02497001. Registered 14 July 2015, https://clinicaltrials.gov/ct2/show/NCT02497001.

Bronchial thermoplasty in asthma: an exploratory histopathological evaluation in distinct asthma endotypes/phenotypes.

BACKGROUND: Bronchial thermoplasty regulates structural abnormalities involved in airway narrowing in asthma. In the present study we aimed to investigate the effect of bronchial thermoplasty on histopathological bronchial structures in distinct asthma endotypes/phenotypes. METHODS: Endobronchial biopsies (n = 450) were collected from 30 patients with severe uncontrolled asthma before bronchial thermoplasty and after 3 sequential bronchial thermoplasties. Patients were classified based on blood eosinophils, atopy, allergy and smoke exposure. Tissue sections were assessed for histopathological parameters and expression of heat-shock proteins and glucocorticoid receptor. Proliferating cells were determined by Ki67-staining. RESULTS: In all patients, bronchial thermoplasty improved asthma control (p < 0.001), reduced airway smooth muscle (p = 0.014) and increased proliferative (Ki67 +) epithelial cells (p = 0.014). After bronchial thermoplasty, airway smooth muscle decreased predominantly in patients with T2 high asthma endotype. Epithelial cell proliferation was increased after bronchial thermoplasty in patients with low blood eosinophils (p = 0.016), patients with no allergy (p = 0.028) and patients without smoke exposure (p = 0.034). In all patients, bronchial thermoplasty increased the expression of glucocorticoid receptor in epithelial cells (p = 0.018) and subepithelial mesenchymal cells (p = 0.033) and the translocation of glucocorticoid receptor in the nucleus (p = 0.036). Furthermore, bronchial thermoplasty increased the expression of heat shock protein-70 (p = 0.002) and heat shock protein-90 (p = 0.001) in epithelial cells and decreased the expression of heat shock protein-70 (p = 0.009) and heat shock protein-90 (p = 0.002) in subepithelial mesenchymal cells. The effect of bronchial thermoplasty on the expression of heat shock proteins -70 and -90 was distinctive across different asthma endotypes/phenotypes. CONCLUSIONS: Bronchial thermoplasty leads to a diminishment of airway smooth muscle, to epithelial cell regeneration, increased expression and activation of glucocorticoid receptor in the airways and increased expression of heat shock proteins in the epithelium. Histopathological effects appear to be distinct in different endotypes/phenotypes indicating that the beneficial effects of bronchial thermoplasty are achieved by diverse molecular targets associated with asthma endotypes/phenotypes.