Covert airflow obstruction dominates the overt ones in interstitial lung disease: An appraisal.

Background & objectives The co-presence of non-emphysematous airflow obstruction in interstitial Lung disease (ILD) is not elaborated. The present study aims the job with spirometry. Methods ILD affected individuals with or without airflow obstruction (FEV1/FVC<0.7 or >0.7) on spirometry were compared in terms of FEV1 and FEF25-75 derived variables [FEF25-75 (%-predicted), FEV1-FEF25-75 distance, reversibility of FEV1 and FEF25-75 to salbutamol and change in FEV1 and FEF25-75 in %-predicted values]. Those showing significant difference (P=0.0001) suggesting obstruction were selected to draw respective receiver operating curve (ROC) curves to identify the best cut-off value for individual parameters. The efficacy of each surrogate was tested to identify airflow obstruction in both the initial 'overlap' as well as the 'unmixed' ILD affected individual for the presence of airflow obstruction. Results FEV1/FVC identified 30 overlap from 235 ILDs. The FEF25-75 (%-predicted), FEV1-FEF25-75 distance, FEF25-75 reversibility (in ml) and FEV1 (%-predicted) were significantly (P<0.0001) different between the two groups. Of these, the FEF25-75 (%-predicted) had high specificity and sensitivity (93.33 and 79.47%) to identify airflow limitation in the initial unmixed ILD-group. The surrogates with their cut off values identified 92 extra individuals making it 122/235 (51.91%) of ILD having airflow obstruction. The 'unmixed' group showed higher frequency and degree of FEV1 reversibility. Interpretation & conclusions The findings of this study suggest that the airflow obstruction in ILD involves both the intrathoracic large and small airways. Although seemingly parallel, their relative status (qualitative and quantitative) needs research especially in light of the a etio pathology and the extent of involvement of ILD.

MiR-1307-5p enhances fibroblast transdifferentiation to exacerbate chronic obstructive pulmonary disease through regulating FBXL16/HIF1α axis.

Chronic obstructive pulmonary disease (COPD) is an irreversible and progressive chronic inflammatory lung disease which affects millions of people worldwide. Activated fibroblasts are observed to accumulate in lung of COPD patients and promote COPD progression through aberrant extracellular matrix (ECM) deposition. In this study, we identified that miR-1307-5p expression was significantly increased in lung fibroblasts derived from COPD patients. Mechanistically, we found that upregulation of miR-1307-5p promoted TGF-ß induced lung fibroblast activation and transdifferentiation. We also identified FBXL16 as a direct target for miR-1307-5p mediated myofibroblast activation in COPD. Knockdown of FBXL16 by siRNA prominently increased the expression of myofibroblast markers in MRC-5 fibroblasts after TGF-ß administration. Ectopic expression of FBXL16 in MRC-5 counteracted miR-1307-5p agomir-induced fibroblast transdifferentiation. Furthermore, We found that miR-1307-5p promoted pulmonary fibroblast transdifferentiation through FBXL16 regulated HIF1α degradation. In general, our findings indicate that miR-1307-5p is important for COPD pathogenesis, and may serve as a potential target for COPD treatment.

Transcriptional profiles of peripheral eosinophils in chronic obstructive pulmonary disease and asthma-An exploratory study.

The role of eosinophilic inflammation in the pathogenesis of chronic obstructive pulmonary disease (COPD) remains ambiguous and likely differs from its role in asthma. The molecular processes underlying the differences between eosinophils from asthma and COPD have not been sufficiently studied. The objective of this study was to compare the transcriptomic profiles of blood eosinophils in COPD and asthma. Eosinophils were isolated from peripheral blood drawn from stable mild-to-moderate COPD and asthma patients. RNA was isolated from eosinophils and sequenced using an NGSelect RNA. The prepared libraries were sequenced on an Illumina platform. The study group included five patients with asthma and four patients with COPD. The RNA-Seq data analysis identified 26 differentially expressed genes between COPD and asthma (according to adjusted p-value). In total, 6 genes were upregulated (e.g. CCL3L1, CCL4L2, GPR82) and 20 were downregulated (e.g. JUN, IFITM3, DUSP1, GNG7) in peripheral eosinophils of COPD patients compared to asthma. The genes associated with signalling of IL-4 and IL-13 pathways were downregulated in COPD eosinophils compared to asthma. In conclusion, blood eosinophils from COPD and asthma patients present different transcriptomic profiles suggesting their different function in pathobiology of both obstructive airway diseases. These differences might indicate the direction of the search of targeted therapy in COPD.

Interaction between CD244 and SHP2 regulates inflammation in chronic obstructive pulmonary disease via targeting the MAPK/NF-κB signaling pathway.

This study delved into the interplay between CD244 and Src Homology 2 Domain Containing Phosphatase-2 (SHP2) in chronic obstructive pulmonary disease (COPD) pathogenesis, focusing on apoptosis and inflammation in cigarette smoke extract (CSE)-treated human bronchial epithelial (HBE) cells. Analysis of the GSE100153 dataset identified 290 up-regulated and 344 down-regulated differentially expressed genes (DEGs). Weighted gene co-expression network analysis (WGCNA) highlighted the turquoise module had the highest correlation with COPD samples. Functional enrichment analysis linked these DEGs to critical COPD processes and pathways like neutrophil degranulation, protein kinase B activity, and diabetic cardiomyopathy. Observations on CD244 expression revealed its upregulation with increasing CSE concentrations, suggesting a dose-dependent relationship with inflammatory cytokines (IL-6, IL-8, TNF-α). CD244 knockdown mitigated CSE-induced apoptosis and inflammation, while overexpression exacerbated these responses. Co-immunoprecipitation (Co-IP) confirmed the physical interaction between CD244 and SHP2, emphasizing their regulatory connection. Analysis of Concurrently, the Nuclear Factor-kappa B (NF-κB) and Mitogen-activated protein kinase (MAPK) signaling pathways showed that modulating CD244 expression impacted key pathway components (p-JNK, p-IKKß, p-ERK, p-P38, p-lkBα, p-P65), an effect reversed upon SHP2 knockdown. These findings underscore the pivotal role of the CD244/SHP2 axis in regulating inflammatory and apoptotic responses in CSE-exposed HBE cells, suggesting its potential as a therapeutic target in COPD treatment strategies.

GATA2 downregulation contributes to pro-inflammatory phenotype and defective phagocytosis of pulmonary macrophages in chronic obstructive pulmonary disease.

Pulmonary macrophages from COPD patients are characterized by lower phagocytic and bactericidal activity whereas there is hypersecretion of pro-inflammatory cytokines. The prominent decline of GATA2 expression in pulmonary macrophages from COPD patients inspired us to figure out its role during COPD development. The expression levels of GATA2 were decreased in alveolar macrophages isolated from cigarette smoke (CS)-induced COPD mice and cigarette smoke extract (CSE)-treated macrophages. In vitro, both CSE and GATA2 knockdown via siRNAs elevated pro-inflammatory cytokines expression whereas inhibiting phagocytosis in macrophages. Integrated analysis of transcriptomics of GATA2-knockdown macrophages and the results of ChIP sequencing of GATA2 together with dual-luciferase reporter assay identified Abca1 and Pacsin1 as functional target genes of GATA2. Mechanistically, ABCA1 mediates the pro-inflammatory secretion phenotype and the dysfunction in early stage of phagocytosis of macrophages through TLR4/MyD88 and MEGF10/GULP1 pathways, respectively. PACSIN1/SUNJ1 partially mediates the disruption effects of GATA2 downregulation on maturation of phagolysosomes in macrophages. Together, our study suggests that GATA2 influences multiple functions of pulmonary macrophages by simultaneous transcriptional regulation of several target genes, contributing to the dysfunctions of pulmonary macrophages in response to CS, which provides an impetus for further investigations of GATA2 or other underappreciated transcription factors as regulatory hubs in COPD pathogenesis.

KDELR2 is necessary for chronic obstructive pulmonary disease airway Mucin5AC hypersecretion via an IRE1α/XBP-1s-dependent mechanism.

Airway mucus hypersecretion, a crucial pathological feature of chronic obstructive pulmonary disease (COPD), contributes to the initiation, progression, and exacerbation of this disease. As a macromolecular mucin, the secretory behaviour of Mucin5AC (MUC5AC) is highly dependent on a series of modifying and folding processes that occur in the endoplasmic reticulum (ER). In this study, we focused on the ER quality control protein KDEL receptor (KDELR) and demonstrated that KDELR2 and MUC5AC were colocalized in the airway epithelium of COPD patients and COPD model rats. In addition, knockdown of KDELR2 markedly reduced the expression of MUC5AC both in vivo and in vitro and knockdown of ATF6 further decreased the levels of KDELR2. Furthermore, pretreatment with 4µ8C, an IRE1α inhibitor, led to a partial reduction in the expression of KDELR2 and MUC5AC both in vivo and in vitro, which indicated the involvement of IRE1α/XBP-1s in the upstream signalling cascade. Our study revealed that KDELR2 plays a crucial role in airway MUC5AC hypersecretion in COPD, which might be dependent on ATF6 and IRE1α/XBP-1s upstream signalling.

Expression of Epithelial Alarmin Receptor on Innate Lymphoid Cells Type 2 in Eosinophilic Chronic Obstructive Pulmonary Disease.

Studies have shown that eosinophilic COPD (eCOPD) is a distinct phenotype of the disease. It is well established that innate lymphoid cells are involved in the development of eosinophilic inflammation. Interleukin(IL)-25, thymic stromal lymphopoietin (TSLP) and IL-33 are a group of cytokines produced by epithelium in response to danger signals, e.g., cigarette smoke, and potent activators of ILC2s. In the present study, we examined circulating and sputum ILC2 numbers and expression of intracellular IL-5 as well as receptors for TSLP, IL-33 and IL-25 by ILC2s in non-atopic COPD patients with and without (neCOPD) airway eosinophilic inflammation and healthy smokers. In addition, we examined the association between ILC2s and clinical indicators of COPD burden (i.e., symptom intensity and risk of exacerbations). ILC2s were enumerated in peripheral blood and induced sputum by means of flow cytometry. We noted significantly greater numbers of airway IL-5+ILC2s and TSLPR+ILC2s in eCOPD compared with neCOPD (p < 0.05 and p < 0.01, respectively) and HSs (p < 0.001 for both). In addition, we showed that IL-5+ILC2s, IL-17RB+ILC2s and ST2+ILC2s are significantly increased in the sputum of eCOPD patients compared with HSs. In all COPD patients, sputum ILC2s positively correlated with sputum eosinophil percentage (r = 0.48, p = 0.002). We did not find any significant correlations between sputum ILC2s and dyspnea intensity as measured by the modified Medical Research Council scale (mMRC) and symptom intensity measured by the COPD Assessment Test (CAT). These results suggest the involvement of epithelial alarmin-activated ILC2s in the pathobiology of eosinophilic COPD.

Hypoxia inducible factor (HIF) 3α prevents COPD by inhibiting alveolar epithelial cell ferroptosis via the HIF-3α-GPx4 axis.

Rationale: COPD patients are largely asymptomatic until the late stages when prognosis is generally poor. In this study, we shifted the focus to pre-COPD and smoking stages, and found enrichment of hypoxia inducible factor (HIF)-3α is in pre-COPD samples. Smoking induced regional tissue hypoxia and emphysema have been found in COPD patients. However, the mechanisms underlying hypoxia especially HIF-3α and COPD have not been investigated. Methods: We performed bulk-RNA sequencing on 36 peripheral lung tissue specimens from non-smokers, smokers, pre-COPD and COPD patients, and using "Mfuzz" algorithm to analysis the dataset dynamically. GSE171541 and EpCAM co-localization analyses were used to explore HIF-3α localization. Further, SftpcCreert2/+R26LSL-Hif3a knock-in mice and small molecular inhibitors in vitro were used to explore the involvement of HIF-3α in the pathophysiology of COPD. Results: Reactive oxygen species (ROS) and hypoxia were enriched in pre-COPD samples, and HIF-3α was downregulated in alveolar epithelial cells in COPD. In vitro experiments using lentivirus transfection, bulk-RNA seq, and RSL3 showed that the activation of the HIF-3α-GPx4 axis inhibited alveolar epithelial cell ferroptosis when treated with cigarettes smoking extracts (CSE). Further results from SftpcCreert2/+R26LSL-Hif3a knock-in mice demonstrated overexpression of HIF-3α inhibited alveolar epithelial cells ferroptosis and prevented the decline of lung function. Conclusion: Hypoxia and oxidation-related damage begins years before the onset of COPD symptoms, suggesting the imbalance and impairment of intracellular homeostatic system. The activation of the HIF-3α-GPx4 axis is a promising treatment target. By leveraging this comprehensive analysis method, more potential targets could be found and enhancing our understanding of the pathogenesis.

Single-cell transcriptomics reveals e-cigarette vapor-induced airway epithelial remodeling and injury.

BACKGROUND: In recent years, e-cigarettes have been used as alternatives among adult smokers. However, the impact of e-cigarette use on human bronchial epithelial (HBE) cells remains controversial. METHODS: We collected primary HBE cells of healthy nonsmokers and chronic obstructive pulmonary disease (COPD) smokers, and analyzed the impact of e- cigarette vapor extract (ECE) or cigarette smoke extract (CSE) on HBE cell differentiation and injury by single-cell RNA sequencing, immunostaining, HE staining, qPCR and ELISA. We obtained serum and sputum from healthy non- smokers, smokers and e-cigarette users, and analyzed cell injury markers and mucin proteins. RESULTS: ECE treatment led to a distinct differentiation program of ciliated cells and unique patterns of their cell-cell communications compared with CSE. ECE treatment caused increased Notch signaling strength in a ciliated cell subpopulation, and HBE cell remodeling and injury including hypoplasia of ciliated cells and club cells, and shorter cilia. ECE-induced hypoplasia of ciliated cells and shorter cilia were ameliorated by the Notch signaling inhibition. CONCLUSIONS: This study reveals distinct characteristics in e-cigarette vapor-induced airway epithelial remodeling, pointing to Notch signaling pathway as a potential targeted intervention for e-cigarette vapor-caused ciliated cell differentiation defects and cilia injury. In addition, a decrease in SCGB1A1 proteins is associated with e- cigarette users, indicating a potential lung injury marker for e-cigarette users.

Differential proteins from EVs identification based on tandem mass tags analysis and effect of Treg-derived EVs on T-lymphocytes in COPD patients.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a widespread respiratory disease. This study examines extracellular vesicles (EVs) and proteins contained in EVs in COPD. METHODS: Blood samples were collected from 40 COPD patients and 10 health controls. Cytokines including IFN-γ, TNF-α, IL-1ß, IL-6, IL-8, and IL-17, were measured by ELISA. Small EVs samples were extracted from plasma and identified by transmission electron microscope (TEM), nanoparticle tracking analysis (NTA), and Western blot. Protein components contained in EVs were analyzed by Tandem Mass Tags (TMT) to identify differential proteins. Treg-derived EV was extracted and added to isolated CD8+, Treg, and Th17 subsets to assess its effect on T-lymphocytes. RESULTS: ELISA revealed higher levels of all cytokines and flow cytometry suggested a higher proportion of Treg and Th17 cells in COPD patients. After identification, TMT analysis identified 207 unique protein components, including five potential COPD biomarkers: BTRC, TRIM28, CD209, NCOA3, and SSR3. Flow cytometry revealed that Treg-derived EVs inhibited differentiation into CD8+, CD4+, and Th17 cells. CONCLUSION: The study shows that cytokines, T-lymphocyte subsets differences in COPD and Treg-derived EVs influence T-lymphocyte differentiation. Identified biomarkers may assist in understanding COPD pathogenesis, prognosis, and therapy. The study contributes to COPD biomarker research.

Lipolysis engages CD36 to promote ZBP1-mediated necroptosis-impairing lung regeneration in COPD.

Lung parenchyma destruction represents a severe condition commonly found in chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide. Promoting lung regeneration is crucial for achieving clinical improvement. However, no therapeutic drugs are approved to improve the regeneration capacity due to incomplete understanding of the underlying pathogenic mechanisms. Here, we identify a positive feedback loop formed between adipose triglyceride lipase (ATGL)-mediated lipolysis and overexpression of CD36 specific to lung epithelial cells, contributing to disease progression. Genetic deletion of CD36 in lung epithelial cells and pharmacological inhibition of either ATGL or CD36 effectively reduce COPD pathogenesis and promote lung regeneration in mice. Mechanistically, disruption of the ATGL-CD36 loop rescues Z-DNA binding protein 1 (ZBP1)-induced cell necroptosis and restores WNT/ß-catenin signaling. Thus, we uncover a crosstalk between lipolysis and lung epithelial cells, suggesting the regenerative potential for therapeutic intervention by targeting the ATGL-CD36-ZBP1 axis in COPD.

Loss of JCAD/KIAA1462 Protects the Lung from Acute and Chronic Consequences of Chronic Obstructive Pulmonary Disease.

Even with recent advances in pathobiology and treatment options, chronic obstructive pulmonary disease (COPD) remains a major contributor to morbidity and mortality. To develop new ways of combating this disease, breakthroughs in our understanding of its mechanisms are sorely needed. Investigating the involvement of underanalyzed lung cell types, such as endothelial cells (ECs), is one way to further our understanding of COPD. JCAD is a junctional protein in endothelial cells (ECs) arising from the KIAA1462 gene, and a mutation in this gene has been implicated in the risk of developing COPD. In our study, we induced inflammation and emphysema in mice via the global knockout of KIAA1462/JCAD (JCAD-KO) and confirmed it in HPMECs and A549 to examine how the loss of JCAD could affect COPD development. We found that KIAA1462/JCAD loss reduced acute lung inflammation after elastase treatment. Even after 3 weeks of elastase, JCAD-KO mice demonstrated a preserved lung parenchymal structure and vasculature. In vitro, after KIAA1462 expression is silenced, both endothelial and epithelial cells showed alterations in pro-inflammatory gene expression after TNF-α treatment. We concluded that JCAD loss could ameliorate COPD through its anti-inflammatory and anti-angiogenic effects, and that KIAA1462/JCAD could be a novel target for COPD therapy.

Differentiation and Growth-Arrest-Related lncRNA (DAGAR): Initial Characterization in Human Smooth Muscle and Fibroblast Cells.

Vascular smooth muscle cells (SMCs) can transition between a quiescent contractile or "differentiated" phenotype and a "proliferative-dedifferentiated" phenotype in response to environmental cues, similar to what in occurs in the wound healing process observed in fibroblasts. When dysregulated, these processes contribute to the development of various lung and cardiovascular diseases such as Chronic Obstructive Pulmonary Disease (COPD). Long non-coding RNAs (lncRNAs) have emerged as key modulators of SMC differentiation and phenotypic changes. In this study, we examined the expression of lncRNAs in primary human pulmonary artery SMCs (hPASMCs) during cell-to-cell contact-induced SMC differentiation. We discovered a novel lncRNA, which we named Differentiation And Growth Arrest-Related lncRNA (DAGAR) that was significantly upregulated in the quiescent phenotype with respect to proliferative SMCs and in cell-cycle-arrested MRC5 lung fibroblasts. We demonstrated that DAGAR expression is essential for SMC quiescence and its knockdown hinders SMC differentiation. The treatment of quiescent SMCs with the pro-inflammatory cytokine Tumor Necrosis Factor (TNF), a known inducer of SMC dedifferentiation and proliferation, elicited DAGAR downregulation. Consistent with this, we observed diminished DAGAR expression in pulmonary arteries from COPD patients compared to non-smoker controls. Through pulldown experiments followed by mass spectrometry analysis, we identified several proteins that interact with DAGAR that are related to cell differentiation, the cell cycle, cytoskeleton organization, iron metabolism, and the N-6-Methyladenosine (m6A) machinery. In conclusion, our findings highlight DAGAR as a novel lncRNA that plays a crucial role in the regulation of cell proliferation and SMC differentiation. This paper underscores the potential significance of DAGAR in SMC and fibroblast physiology in health and disease.

MAP2K1 dampens cigarette smoke-induced inflammation via suppression of type I interferon pathway activation.

Chronic obstructive pulmonary disease (COPD), comprised of chronic bronchitis and emphysema, is a leading cause of morbidity and mortality worldwide. Mitogen-activated protein 2 kinase (MAP2K) pathway activation is present in COPD lung tissue and a genetic polymorphism in Map2k1 associates with FEV1 decline in COPD, suggesting it may contribute to disease pathogenesis. To test the functional contribution of Map2k1 in cigarette smoke (CS)-induced lung inflammation, we used a short-term CS exposure model in mice deficient in myeloid Map2k1 (LysmCre+Mek1fl) and wild-type mice (Mek1fl). Mice deficient in myeloid Map2k1 had enhanced CS-induced lung inflammation characterized by increased neutrophil recruitment, vascular leak, augmented expression of elastolytic matrix metalloproteinases, and increased type I interferon-stimulated gene expression. The augmented neutrophilic inflammatory response could be abrogated by IFNAR1 blockade. These findings indicate that myeloid Map2k1 regulates the immune response to CS via inhibition of the type I interferon pathway. Overall, these results suggest that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation and its expression is protective.NEW & NOTEWORTHY Activation of the mitogen-activated protein kinases (MAPK)-ERK1/2 pathway is present in COPD lung tissue compared with healthy lungs. Our study using mice deficient in myeloid Map2k1 reveals that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation via suppression of type I interferon responses, and its expression is protective.

IL-13 induces loss of CFTR in ionocytes and reduces airway epithelial fluid absorption.

The airway surface liquid (ASL) plays a crucial role in lung defense mechanisms, and its composition and volume are regulated by the airway epithelium. The cystic fibrosis transmembrane conductance regulator (CFTR) is abundantly expressed in a rare airway epithelial cell type called an ionocyte. Recently, we demonstrated that ionocytes can increase liquid absorption through apical CFTR and basolateral barttin/chloride channels, while airway secretory cells mediate liquid secretion through apical CFTR channels and basolateral NKCC1 transporters. Th2-driven (IL-4/IL-13) airway diseases, such as asthma, cause goblet cell metaplasia, accompanied by increased mucus production and airway secretions. In this study, we investigate the effect of IL-13 on chloride and liquid transport performed by ionocytes. IL-13 treatment of human airway epithelia was associated with reduced epithelial liquid absorption rates and increased ASL volume. Additionally, IL-13 treatment reduced the abundance of CFTR-positive ionocytes and increased the abundance of CFTR-positive secretory cells. Increasing ionocyte abundance attenuated liquid secretion caused by IL-13. Finally, CFTR-positive ionocytes were less common in asthma and chronic obstructive pulmonary disease and were associated with airflow obstruction. Our findings suggest that loss of CFTR in ionocytes contributes to the liquid secretion observed in IL-13-mediated airway diseases.

OSGIN1 regulates PM2.5-induced fibrosis via mediating autophagy in an in vitro model of COPD.

Fine particulate matter (PM2.5) has been identified as a significant contributing factor to the exacerbation of chronic obstructive pulmonary disease (COPD). It has been observed that PM2.5 may induce lung fibrosis in COPD, although the precise molecular mechanism behind this remains unclear. In a previous study, we demonstrated that PM2.5 upregulates oxidative stress induced growth inhibitor 1 (OSGIN1), which in turn leads to injury in airway epithelial cells, thereby, suggesting a potential link between PM2.5 exposure and COPD. Based on this, we hypothesized that OSGIN1 plays a role in PM2.5-induced fibrosis in COPD. Human bronchial epithelial cells (HBEs) were treated with cigarette smoke extract (CSE) to construct an in vitro model of COPD. Our findings revealed that PM2.5 increased fibrosis indicators and upregulated OSGIN1 in CSE-stimulated HBEs (CSE-HBEs), and knockdown of OSGIN1 reduced the expression of fibrosis indicators. Through the use of microRNA target prediction software and the Gene Expression Omnibus database, we predicted miRNAs that targeted OSGIN1 in COPD. Subsequently, real-time polymerase chain reaction and western blot analysis confirmed that PM2.5 modulated miR-654-5p to regulate OSGIN1 in CSE-HBEs. Western blot demonstrated that OSGIN1 induced autophagy, thereby exacerbating fibrosis in CSE-HBEs. In summary, our results suggest that PM2.5 upregulates OSGIN1 through inhibiting miR-654-5p, leading to increased autophagy and fibrosis in CSE-HBEs.

SMAD4 promotes EMT in COPD airway remodeling induced by cigarette smoke through interaction with O-GlcNAc transferase.

Cigarette smoke (CS) is a prevalent chemical indoor air contaminant known to be the primary cause of EMT during airway remodeling in COPD. While some evidence indicates the involvement of SMAD4 in EMT across certain diseases, its specific role in CS-induced EMT in airway remodeling associated with COPD is not established. In our research, we observed a substantial upregulation in SMAD4 expression, O-GlcNAcylation and EMT in patients with COPD, as well as in vitro and in vivo COPD models induced by CS, than those of the controls. Downregulation of SMAD4 resulted in a reduction in CS-induced EMT in vitro and in vivo. As a post-translational modification of proteins, O-GlcNAcylation is dynamically controlled by the duo of enzymes: O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) and O-GlcNAcase (OGA). We further discovered the enhancement of O-GlcNAcylation levels induced by CS was due to an elevated OGT expression, as the expression of OGA remained unchanged. Using an OGT inhibitor (OSMI-1) counteracted the effects of SMAD4 on EMT. Whereas, overexpressing OGT increased SMAD4 expression and promoted EMT. OGT-mediated SMAD4 O-GlcNAcylation shielded SMAD4 from proteasomal degradation by reducing its ubiquitination, thereby aiding in SMAD4 stabilization in response to EMT induced by CS. Overall, this research uncovers a fresh pathway for CS-induced EMT in the airway remodeling of COPD and offers valuable insights.

Citrullination, a novel posttranslational modification of elastin, is involved in COPD pathogenesis.

Elastin is an extracellular matrix protein (ECM) that supports elasticity of the lung, and in patients with chronic obstructive pulmonary disease (COPD) and emphysema, the structural changes that reduce the amount of elastic recoil, lead to loss of pulmonary function. We recently demonstrated that elastin is a target of peptidyl arginine deiminase (PAD) enzyme-induced citrullination, thereby leading to enhanced susceptibility of this ECM protein to proteolysis. This study aimed to investigate the impact of PAD activity in vivo and furthermore assessed whether pharmacological inhibition of PAD activity protects against pulmonary emphysema. Using a Serpina1a-e knockout mouse model, previously shown to develop inflammation-mediated emphysema, we validated the involvement of PADs in airway disease. In line with emphysema development, intratracheal administration of lipopolysaccharide in combination with PADs provoked significant airspace enlargement (P < 0.001) and diminished lung function, including loss of lung tissue elastance (P = 0.0217) and increases in lung volumes (P = 0.0463). Intraperitoneal treatment of mice with the PAD inhibitor, BB-Cl-amidine, prevented PAD/LPS-mediated lung function decline and emphysema and reduced levels of citrullinated airway elastin (P = 0.0199). These results provide evidence for the impact of PADs on lung function decline, indicating promising potential for the future development of PAD-based therapeutics for preserving lung function in patients with COPD.NEW & NOTEWORTHY This study provides evidence for the impact of peptidyl arginine deiminase (PAD) enzymes on lung function decline, indicating promising potential for the future development of PAD-based therapeutics for preserving lung function in patients with COPD.

Effect of physical activity in lymphocytes senescence burden in patients with COPD.

Chronic obstructive pulmonary disease (COPD) is regarded as an accelerated-age disease in which chronic inflammation, maladaptive immune responses, and senescence cell burden coexist. Accordingly, cellular senescence has emerged as a potential mechanism involved in COPD pathophysiology. In this study, 25 stable patients with COPD underwent a daily physical activity promotion program for 6 mo. We reported that increase of physical activity was related to a reduction of the senescent cell burden in circulating lymphocytes of patients with COPD. Senescent T-lymphocyte population, characterized by absence of surface expression of CD28, was reduced after physical activity intervention, and the reduction was associated to the increase of physical activity level. In addition, the mRNA expression of cyclin-dependent kinase inhibitors, a hallmark of cell senescence, was reduced and, in accordance, the proliferative capacity of lymphocytes was improved postintervention. Moreover, we observed an increase in functionality in T cells from patients after intervention, including improved markers of activation, enhanced cytotoxicity, and altered cytokine secretions in response to viral challenge. Lastly, physical activity intervention reduced the potential of lymphocytes' secretome to induce senescence in human primary fibroblasts. In conclusion, our study provides, for the first time, evidence of the potential of physical activity intervention in patients with COPD to reduce the senescent burden in circulating immune cells.NEW & NOTEWORTHY For the first time, we identified in patients with COPD a relation between physical activity intervention with respiratory function improvement and cellular senescence burden in lymphocytes that improved the T cell functionality and proliferative capacity of patients. In addition, our experiments highlight the possible impact of T-cell senescence in other cell types which could be related to some of the clinical lung complications observed in COPD.

Role of ATG4 Autophagy-Related Protein Family in the Lower Airways of Patients with Stable COPD.

Autophagy is a complex physiological pathway mediating homeostasis and survival of cells degrading damaged organelles and regulating their recycling. Physiologic autophagy can maintain normal lung function, decrease lung cellular senescence, and inhibit myofibroblast differentiation. It is well known that autophagy is activated in several chronic inflammatory diseases; however, its role in the pathogenesis of chronic obstructive pulmonary disease (COPD) and the expression of autophagy-related genes (ATGs) in lower airways of COPD patients is still controversial. The expression and localization of all ATG proteins that represented key components of the autophagic machinery modulating elongation, closure, and maturation of autophagosome membranes were retrospectively measured in peripheral lungs of patients with stable COPD (n = 10), control smokers with normal lung function (n = 10), and control nonsmoking subjects (n = 8) using immunohistochemical analysis. These results show an increased expression of ATG4 protein in alveolar septa and bronchiolar epithelium of stable COPD patients compared to smokers with normal lung function and non-smoker subjects. In particular, the genes in the ATG4 protein family (including ATG4A, ATG4B, ATG4C, and ATG4D) that have a key role in the modulation of the physiological autophagic machinery are the most important ATGs increased in the compartment of lower airways of stable COPD patients, suggesting that the alteration shown in COPD patients can be also correlated to impaired modulation of autophagic machinery modulating elongation, closure, and maturation of autophagosomes membranes. Statistical analysis was performed by the Kruskal-Wallis test and the Mann-Whitney U test for comparison between groups. A statistically significant increased expression of ATG4A (p = 0.0047), ATG4D (p = 0.018), and ATG5 (p = 0.019) was documented in the bronchiolar epithelium as well in alveolar lining for ATG4A (p = 0.0036), ATG4B (p = 0.0054), ATG4C (p = 0.0064), ATG4D (p = 0.0084), ATG5 (p = 0.0088), and ATG7 (p = 0.018) in patients with stable COPD compared to control groups. The ATG4 isoforms may be considered as additional potential targets for the development of new drugs in COPD.