Autophagy Promotes Cigarette Smoke-Initiated and Elastin-Driven Bronchitis-Like Airway Inflammation in Mice

The role and mechanism of macrophage autophagy in the experimental model of chronic obstructive pulmonary disease

INTRODUCTION

Macrophages play an important role in chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS) impairs autophagy in alveolar macrophages from COPD patients, and autophagic impairment leads to reduced clearance of protein aggregates, dysfunctional mitochondria, and defective bacterial delivery to lysosomes. However, the exact function of lung macrophage autophagy in the pathogenesis of CS-induced COPD remains largely unknown.

METHODS

Western blot detected the expression of autophagy-related proteins induced by CSE. The model of COPD mice was established by CS exposure combined with CSE intraperitoneal injection. Double immunofluorescence was used to measure the CD206+LC3B+ cells. The morphological changes and effects on lung function were observed. Masson staining detected the changes in collagen fibers in lung tissue. The expression levels of E-cadherinb and N-cadherinb were detected by immunohistochemistry. Western blot detected the expression of ATP6V1E1 in lung tissue.

RESULTS

At 24 hours of exposure to CSE, the expression levels of LC3B (microtubule-associated protein 1A/1B-light chain 3B) and P62 (nucleoporin 62) were highest at 1% CSE and AGT5 (nucleoporin 62) at 2.5% CSE; at 48 hours, the expression levels of LC3B, P62 and AGT5 were highest at 2.5% CSE, and as the intervention time increased.CD206+LC3B+ cells were significantly higher in the COPD group. Enhanced macrophage autophagy may promote emphysema formation and aggravate lung function damage. The expression of E-cadherinb in lung tissue of the COPD group was decreased, and N-cadherinb expression was increased; the expression of E-cadherinb was increased, and N-cadherinb expression was decreased in ATG5myeΔ COPD mice. The expression of ATP6V1E1 in the lung tissue was increased in the COPD group; ATP6V1E1 expression was decreased in the lung tissues of ATG5myeΔ COPD mice.

CONCLUSIONS

CSE enhanced macrophage autophagy, leads to increased lung function impairment and collagenous fiber in lung tissue, as well as promotes epithelial-mesenchymal transition, and eventually leads to small airway remodeling, which may be achieved through the ATG5/ATP6V1E1 pathway.

Autophagy Induced by Low Shear Stress Leads to Endothelial Glycocalyx Disruption

INTRODUCTION

Previous studies have confirmed that low shear stress (LSS) induces glycocalyx disruption, leading to endothelial dysfunction. However, the role of autophagy in LSS-induced glycocalyx disruption and relevant mechanism are not clear. In this study, we hypothesized that LSS may promote autophagy, disrupting the endothelium glycocalyx.

METHODS

Human umbilical vein endothelial cells were subjected to physiological shear stress and LSS treatments, followed by the application of autophagy inducers and inhibitors. Additionally, cells were treated with specific matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) inhibitor. The expression of autophagic markers, glycocalyx, MMP-2, and MMP-9 was measured.

RESULTS

LSS impacted the expression of endothelium autophagy markers, increasing the expression of LC3II.LC3I-1 and Beclin-1, and decreasing the levels of p62, accompanied by glycocalyx disturbance. Moreover, LSS upregulated the expression of MMP-2 and MMP-9 and downregulated the levels of syndecan-1 and heparan sulfate (HS). Additionally, expression of MMP-2 and MMP-9 was increased by an autophagy promoter but was decreased by autophagy inhibitor treatment under LSS. Autophagy and MMP-2 and MMP-9 further caused glycocalyx disruption.

CONCLUSION

LSS promotes autophagy, leading to glycocalyx disruption. Autophagy increases the expression of MMP-2 and MMP-9, which are correlated with the glycocalyx destruction induced by LSS.

Global Trends in Research Regarding Macrophages Associated with Chronic Obstructive Pulmonary Disease: A Bibliometric Analysis from 2011 to 2022

Purpose

Chronic obstructive pulmonary disease (COPD) is a prevalent respiratory condition characterized by chronic airway inflammation, where macrophages from the innate immune system may exert a pivotal influence. Our study aimed to summarize the present state of knowledge and to identify the focal points and emerging developments regarding macrophages associated with COPD through bibliometrics.

Methods

Publications regarding research on macrophages associated with COPD from January 1, 2011, to January 1, 2022, were retrieved from the Science Citation Index-Expanded (SCI-E) which is part of the Web of Science database. In total, 1521 publications were analyzed using bibliometric methodology. VOSviewer was used to analyze the annual publications, countries, institutions, authors, journals, and research hotspots.

Results

Based on the bibliometric analysis, publications relating to macrophages associated with COPD tended to increase from 2011 to 2022. The United States was the largest producer and most influential country in this field. Research during the past decade has focused on inflammation in the lungs. Most previous studies have mainly focused on the mechanisms that promote the initiation and progression of COPD. Macrophage-related oxidative stress and immunity, communication between macrophages and epithelial cells, and interventions for acute exacerbations have become the focus of more recent studies and will become a hot topic in the future.

Conclusion

Global research on macrophage-associated COPD has been growing rapidly in the past decade. The hot topics in this field gradually tended to shift focus from "inflammation" to "oxidative stress", "epithelial-cells", and "exacerbations". The significance of macrophages in coordinating immune responses, interacting with other cells, and exhibiting dysregulated capacities has attracted increasing attention to COPD pathogenesis. The adoption of new technologies may provide a more promising and comprehensive understanding of the specific role of macrophages in COPD in the future.

The Mechanisms of Resistin-Like Molecule-β-Mediated Airway Inflammation in Chronic Obstructive Pulmonary Disease via Autophagy

Background

The role of irreversible airway inflammatory damage in chronic obstructive pulmonary disease (COPD) progression is evident. Autophagy is an essential process in the cellular material metabolic cycle, and a family of resistant vegetative molecules may be involved in the COPD autophagic process. In this study, we investigated the mechanism of resistin-like molecule β (RELMβ) in COPD smoking-induced autophagy.

Methods

Firstly, the expression differences of RELMβ and autophagy markers between COPD and control groups were analyzed in the Gene Expression Omnibus (GEO) datasets and clinical specimens. Secondly, in vitro and in vivo experiments were conducted using immunoblotting, immunofluorescence, immunohistochemistry, and other methods to investigate the mechanism by which RELMβ promotes airway inflammation through autophagy in a cigarette smoke extract-induced 16HBE cell inflammation model and a cigarette smoke-induced COPD-like mouse model. In addition, immunoprecipitation was used to analyze the binding of RELMβ to the membrane protein TLR4.

Results

The expression of RELMβ and autophagy genes p62 and LC3B in lung tissue of COPD patients was significantly increased. RELMβ can mediate the activation of autophagy in 16HBE cells, and through autophagy, it increases the expression of inflammatory cytokines in a cigarette smoke extract-induced 16HBE cell inflammation model. RELMβ promotes cigarette smoke-induced COPD-like mouse airway inflammation through autophagy, and RELMβ can mediate signal transduction through the cell membrane receptor TLR4.

Conclusion

The RELMβ binds to TLR4 to encourage signal transduction and that RELMβ can promote inflammation in smoky COPD lungs through autophagy.

SIRT1 as a Potential Therapeutic Target for Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common, preventable, and treatable disease characterized by irreversible airflow obstruction and lung function decline. It is well established that COPD represents a major cause of morbidity and mortality globally. Due to the substantial economic and social burdens associated with COPD, it is necessary to discover new targets and develop novel beneficial therapies. Although the pathogenesis of COPD is complex and remains to be robustly elucidated, numerous studies have shown that oxidative stress, inflammatory responses, cell apoptosis, autophagy, and aging are involved in the pathogenesis of COPD. Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase belonging to the silent information regulator 2 (Sir2) family. Multiple studies have indicated that SIRT1 plays an important role in oxidative stress, apoptosis, inflammation, autophagy, and cellular senescence, which contributes to the pathogenesis and development of COPD. This review aimed to discuss the functions and mechanisms of SIRT1 in the progression of COPD and concluded that SIRT1 activation might be a potential therapeutic strategy for COPD.

Senescence: Pathogenic Driver in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is recognized as a disease of accelerated lung aging. Over the past two decades, mounting evidence suggests an accumulation of senescent cells within the lungs of patients with COPD that contributes to dysregulated tissue repair and the secretion of multiple inflammatory proteins, termed the senescence-associated secretory phenotype (SASP). Cellular senescence in COPD is linked to telomere dysfunction, DNA damage, and oxidative stress. This review gives an overview of the mechanistic contributions and pathologic consequences of cellular senescence in COPD and discusses potential therapeutic approaches targeting senescence-associated signaling in COPD.

Transcriptomic analysis and validation reveal the pathogenesis and a novel biomarker of acute exacerbation of chronic obstructive pulmonary disease

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is the main factor that leads to the deterioration of the disease. Currently, the diagnosis of AECOPD mainly relies on clinical manifestations, good predictors or biomarkers are lacking. We aim to reveal specific biomarkers and potential pathogenesis of AECOPD and provide a research basis for the diagnosis and treatment.

Methods

Four patients with AECOPD, four patients with stable COPD, and five control subjects were enrolled for RNA sequencing and KEGG analysis. The mRNA level of target genes was verified by quantitative real-time PCR (qPCR) with an expanded sample size (30 patients with AECOPD, 27 patients with stable COPD, and 35 control subjects). ELISA and immunofluorescence were used to identify the target proteins. Furthermore, the expression and function of WNT/β-catenin signaling pathway were assessed in animal models of COPD.

Results

RNA sequencing showed that 54 genes were up-regulated and 111 genes were down-regulated in the AECOPD. Differentially expressed genes were mainly enriched in WNT signaling pathway, et al. QPCR revealed that multi-genes of the WNT/β-catenin signaling were significantly down-regulated in AECOPD (P < 0.05), and β-catenin protein was significantly decreased in plasma of AECOPD and stable COPD (P < 0.01), while phosphorylated β-catenin was significantly up-regulated in peripheral blood mononuclear cells of AECOPD (P < 0.05). Similarly, WNT ligands, WNT receptors, and downstream signaling molecules were down-regulated, with an increased phosphorylated β-catenin protein in animal models of COPD. Activation of WNT/β-catenin signaling pathway by lithium chloride reduced the expression of phosphorylated β-catenin and ameliorated the COPD-like airway inflammation in mice.

Conclusion

WNT/β-catenin signaling pathway is down-regulated in AECOPD patients and in animal models of COPD. Increased expression of phosphorylated β-catenin in the blood might be a potential biomarker of AECOPD. Activation of WNT/β-catenin pathway may also represent a therapeutic target for AECOPD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01950-w.