Impaired autophagy in the lower airways and lung parenchyma in stable COPD

Quercetin improves airway remodeling in COPD rats by suppressing phenotypic switch of ASMCs via inhibiting the Wnt5a/β-catenin pathway

BACKGROUND AND PURPOSE

Airway remodeling in chronic obstructive pulmonary disease (COPD) is a contributor to airflow limitation, promotes disease progression, and affects disease outcome and prognosis. Quercetin has been identified as a potential therapeutic agent for COPD. Currently, there is insufficient research providing direct evidence to support this hypothesis. The present study investigates the therapeutic effects and the underlying mechanisms of quercetin in the alleviation of airway remodeling in rat models of COPD.

EXPERIMENTAL STEPS

This study used a network pharmacology approach to predict, for the first time, the potential molecular targets of quercetin in COPD. The effects of quercetin on phenotypic switching and mitochondrial function of ASMCs were assessed in vitro using CCK-8, EdU staining, migration assays, western blotting, and JC-1 staining. Additionally, the interaction between Wnt5a and quercetin was analyzed via molecular docking, and findings were experimentally confirmed using the cellular thermal shift assay (CETSA). Quercetin's influence on airway remodeling in COPD was examined in vivo through pulmonary function evaluation, H&E staining, and Modified Sirius Red staining. Molecular alterations associated with phenotypic switching, oxidative stress, autophagy and Wnt5a/β-Catenin pathway were examined by Western blotting, immunofluorescence, immunohistochemistry, DHE staining and ELISA.

KEY RESULTS

The results showed that quercetin has a beneficial therapeutic effect on COPD. Its ability to mitigate airway remodeling is linked to modulating autophagy levels, reducing oxidative stress, alleviating mitochondrial damage, and influencing the phenotypic switch in ASMCs. By increasing oxidative stress tolerance, quercetin reduces mitochondrial damage and regulates the phenotypic switch in ASMCs. Furthermore, quercetin suppresses autophagy hyperactivation, which subsequently lowers oxidative stress levels in ASMCs. Notably, quercetin modulates autophagy through the regulation of the Wnt5a/β-catenin signaling pathway.

CONCLUSION AND IMPLICATIONS

In conclusion, quercetin demonstrates potential therapeutic effects in COPD by suppressing the Wnt5a/β-cateninsignaling pathway, autophagy as well as oxidative stress, and thereby alleviating mitochondrial damage and the phenotypic switch in ASMCs. These findings may have clinical applications and offer new insights for the development of COPD treatments.

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.

The role of quercetin in ameliorating bleomycin-induced pulmonary fibrosis: insights into autophagy and the SIRT1/AMPK signaling pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology characterized by a constant incidence rate. Unfortunately, effective pharmacological treatments for this condition are lacking and the identification of novel therapeutic approaches and underlying pathological mechanisms are required. This study investigated the potential of quercetin in alleviating pulmonary fibrosis by promoting autophagy and activation of the SIRT1/AMPK pathway.

METHODS

Mouse models of IPF were divided into four treatment groups: control, bleomycin (BLM), quercetin (Q), and quercetin + EX-527 (Q + E) treatment. Pulmonary fibrosis was induced in the mouse models through intratracheal instillation of BLM. Various indexes were identified through histological staining, Western blotting analysis, enzyme-linked immunosorbent assay, immunohistochemistry, and transmission electron microscopy.

RESULTS

Quercetin treatment ameliorated the pathology of BLM-induced pulmonary fibrosis of mice by reducing α-smooth muscle actin (α-SMA), collagen I (Col I), and collagen III (Col III) levels, and also improved the level of E-cadherin in lung tissue. Furthermore, Quercetin significantly enhanced LC3II/LC3I levels, decreased P62 expression, and increased the number of autophagosomes in lung tissue. These effects were accompanied by the activation of the SIRT1/AMPK pathway. Treatment with EX-527, an inhibitor for SIRT1, reversed all effects induced by quercetin.

CONCLUSION

This study showed that quercetin could alleviate pulmonary fibrosis and improve epithelial-mesenchymal transition by acting on the SIRT1/AMPK signaling pathway, which may be achieved by regulating the level of autophagy.

Inhalation exposure-induced toxicity and disease mediated via mTOR dysregulation

Environmental air pollution is a global health concern, associated with multiple respiratory and systemic diseases. Epidemiological supports continued urbanization and industrialization increasing the prevalence of inhalation exposures. Exposure to these inhaled pollutants induces toxicity via activation of numerous cellular mechanisms including oxidative stress, autophagy, disrupted cellular metabolism, inflammation, tumorigenesis, and others contributing to disease development. The mechanistic target of rapamycin (mTOR) is a key regulator involved in various cellular processes related to the modulation of metabolism and maintenance of homeostasis. Dysregulation of mTOR occurs following inhalation exposures and has also been implicated in many diseases such as cancer, obesity, cardiovascular disease, diabetes, asthma, and neurodegeneration. Moreover, mTOR plays a fundamental role in protein transcription and translation involved in many inflammatory and autoimmune diseases. It is necessary to understand inhalation exposure-induced dysregulation of mTOR since it is key regulator which may contribute to numerous disease processes. This mini review evaluates the available literature regarding several types of inhalation exposure and their impacts on mTOR signaling. Particularly we focus on the mTOR signaling pathway related outcomes of autophagy, lipid metabolism, and inflammation. Furthermore, we will examine the implications of dysregulated mTOR pathway in exposure-induced diseases. Throughout this mini review, current gaps will be identified related to exposure-induced mTOR dysregulation which may enable the targeting of mTOR signaling for the development of therapeutics.

Dysfunction in IGF2R Pathway and Associated Perturbations in Autophagy and WNT Processes in Beckwith-Wiedemann Syndrome Cell Lines

Beckwith-Wiedemann Syndrome (BWS) is an imprinting disorder characterized by overgrowth, stemming from various genetic and epigenetic changes. This study delves into the role of IGF2 upregulation in BWS, focusing on insulin-like growth factor pathways, which are poorly known in this syndrome. We examined the IGF2R, the primary receptor of IGF2, WNT, and autophagy/lysosomal pathways in BWS patient-derived lymphoblastoid cell lines, showing different genetic and epigenetic defects. The findings reveal a decreased expression and mislocalization of IGF2R protein, suggesting receptor dysfunction. Additionally, our results point to a dysregulation in the AKT/GSK-3/mTOR pathway, along with imbalances in autophagy and the WNT pathway. In conclusion, BWS cells, regardless of the genetic/epigenetic profiles, are characterized by alteration of the IGF2R pathway that is associated with the perturbation of the autophagy and lysosome processes. These alterations seem to be a key point of the molecular pathogenesis of BWS and potentially contribute to BWS's characteristic overgrowth and cancer susceptibility. Our study also uncovers alterations in the WNT pathway across all BWS cell lines, consistent with its role in growth regulation and cancer development.