Insufficient autophagy promotes bronchial epithelial cell senescence in chronic obstructive pulmonary disease

Mechanisms coupling the mTOR pathway to chronic obstructive pulmonary disease (COPD) pathogenesis

Chronic Obstructive Pulmonary Disease (COPD) is a poorly reversible respiratory disorder distinguished by dyspnea, cough, expectoration and exacerbations due to abnormality of airways or emphysema. In this review, we consider the therapeutic potential of targeting Mammalian target of Rapamycin (mTOR) for treating COPD. The mTOR is a highly conserved serine-threonine protein kinase that integrates signals from growth factors and nutrients to control protein synthesis, lipid biogenesis and metabolism. Dysregulated mTOR pathway signaling due to genetic factors or cigarette smoking impairs autophagy, driving the buildup of abnormal cells and damaged proteins, resulting in inflammation and oxidative stress. Persistent mTOR activation also contributes to pulmonary vascular cell proliferation, facilitating the development of pulmonary resistance in COPD. Rapamycin, an inhibitor of mTOR, prevents the buildup of senescent cells in the lungs of COPD patients and inhibits the release of lung tissue-damaging proteases. mTOR also impacts the corticosteroid sensitivity in COPD patients by regulating the levels of histone deacetylases. The emerging role of gut-lung axis dysbiosis in the progression of COPD and its influence on mTOR further highlights the relevance of the mTOR pathway in COPD pathophysiology.

Ginkgo biloba extract alleviates ferroptosis in lung epithelial cells induced by cigarette smoke extract through miR-3,619-5p/GPX4 axis

Ginkgo biloba extract (GBE), a therapeutic drug, has anti-inflammatory and antioxidant effects that protect cells from harmful substances. Although GBE has been extensively studied in the prevention and treatment of lung diseases, its mechanism of action in chronic obstructive pulmonary disease (COPD) is unclear. In the present study, cigarette smoke extract (CSE) and cigarette smoke (CS) were used to induce COPD in cell and animal models. The expression of related genes and proteins was detected, and cell damage and lung tissue damage were evaluated via CCK-8 assays, flow cytometry analyses, ELISA, and HE staining. In HBE cells, the expression of miR-3,619-5p was upregulated after CSE induction. However, GBE treatment alleviated the impact of CSE on HBE cell damage and alleviated COPD in vivo. In addition, GBE treatment increased the expression of GPX4 by inhibiting the expression of miR-3,619-5p, and it reduced the release of the IL-6, IL-8, and TNF-α inflammatory factors. Moreover, GBE treatment decreased the production of ROS and MDA, as well as decreased the expression of the ferroptosis-related protein ACSL4, and it promoted the production of GSH and the expression of FTH1. Further, GBE treatment improved cell viability, inhibited ferroptosis, and ultimately alleviated COPD. The present findings suggest that GBE alleviates the progression of COPD through the inhibitory effect of the miR-3,619-5p/GPX4 axis on the ferroptosis process and that GBE may be an effective treatment option for COPD.

Selective protein degradation through chaperone‑mediated autophagy: Implications for cellular homeostasis and disease (Review)

Cells rely on autophagy for the degradation and recycling of damaged proteins and organelles. Chaperone-mediated autophagy (CMA) is a selective process targeting proteins for degradation through the coordinated function of molecular chaperones and the lysosome‑associated membrane protein‑2A receptor (LAMP2A), pivotal in various cellular processes from signal transduction to the modulation of cellular responses under stress. In the present review, the intricate regulatory mechanisms of CMA were elucidated through multiple signaling pathways such as retinoic acid receptor (RAR)α, AMP‑activated protein kinase (AMPK), p38‑TEEB‑NLRP3, calcium signaling‑NFAT and PI3K/AKT, thereby expanding the current understanding of CMA regulation. A comprehensive exploration of CMA's versatile roles in cellular physiology were further provided, including its involvement in maintaining protein homeostasis, regulating ferroptosis, modulating metabolic diversity and influencing cell cycle and proliferation. Additionally, the impact of CMA on disease progression and therapeutic outcomes were highlighted, encompassing neurodegenerative disorders, cancer and various organ‑specific diseases. Therapeutic strategies targeting CMA, such as drug development and gene therapy were also proposed, providing valuable directions for future clinical research. By integrating recent research findings, the present review aimed to enhance the current understanding of cellular homeostasis processes and emphasize the potential of targeting CMA in therapeutic strategies for diseases marked by CMA dysfunction.

Fluorofenidone alleviates cigarette smoke exposure-induced chronic lung injury by targeting ferroptosis

Chronic obstructive pulmonary disease (COPD) is a common condition that poses significant health risks to humans. Pulmonary interstitial fibrosis (PIF) often manifests in advanced stages of COPD. Fluorofenidone (AKF) has a wide range of pharmacological effects, including anti-fibrotic, antioxidant, and anti-inflammatory effects. Therefore, this study aimed to assess the role of AKF in lung injury and its underlying mechanisms. The COPD mice model was constructed by cigarette smoke (CS) combined with lipopolysaccharide (LPS) treatment. The effect of AKF on COPD mice was evaluated by lung injury, lipid peroxidation, inflammatory factors, and the expression of ferroptosis markers. Furthermore, the normal human bronchial epithelial cell line, Beas-2B, was used to verify the mechanism underlying the association between ferroptosis and inflammation. AKF attenuated the cigarette smoke (CS)/LPS-induced inflammatory response in the mouse lungs. Additionally, AKF attenuated the CS/LPS-induced fibrosis response in the mouse lungs. AKF inhibits ferroptosis in lung tissues of CS/LPS-exposed mice. Furthermore, AKF suppressed the inflammatory response and ferroptosis in CSE-treated BEAS-2B cells via NF-κB signaling pathway. AKF can function as a novel ferroptosis inhibitor by inhibiting NF-κB to inhibit airway inflammation and fibrosis, providing a scientific basis for the use of AKF to prevent the progression of COPD and pulmonary fibrosis.

Autophagy in the Cellular Consequences of Tobacco Smoking: Insights into Senescence

Smoking is a significant contributing factor to the development of many complex diseases. One of the most important stimuli for aging in the human body is constant exposure to environmental factors such as cigarette smoke. Free radicals in cigarette smoke cause reactive oxygen species production at the cellular level and induce inflammatory responses. The respiratory system of smokers exhibits age-related characteristics, such as enhanced oxidative stress, accumulated damaged proteins, and increased inflammation. Autophagy is triggered by tobacco smoke as a protective mechanism to prevent and reduce molecular stress. However, smoking can interfere with the normal functioning of autophagy in various ways. Smoking-induced impairment of autophagy leads to irreversible cellular damage accumulation, causing cells to undergo cellular aging or senescence. Senescent cells lose their ability to divide and display a distinct secretory phenotype called the senescence-associated secretory phenotype (SASP) and produce numerous growth factors, immune modulators, and inflammatory cytokines. This review discusses the effects of tobacco smoke exposure on autophagy alteration, cellular aging, and senescence induction in exposed animal models, as well as in exposed epithelial and immune cells in the body.

mTORC2: A neglected player in aging regulation

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a pivotal role in various biological processes, through integrating external and internal signals, facilitating gene transcription and protein translation, as well as by regulating mitochondria and autophagy functions. mTOR kinase operates within two distinct protein complexes known as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which engage separate downstream signaling pathways impacting diverse cellular processes. Although mTORC1 has been extensively studied as a pro-proliferative factor and a pro-aging hub if activated aberrantly, mTORC2 received less attention, particularly regarding its implication in aging regulation. However, recent studies brought increasing evidence or clues for us, which implies the associations of mTORC2 with aging, as the genetic elimination of unique subunits of mTORC2, such as RICTOR, has been shown to alleviate aging progression in comparison to mTORC1 inhibition. In this review, we first summarized the basic characteristics of mTORC2, including its protein architecture and signaling network. We then focused on reviewing the molecular signaling regulation of mTORC2 in cellular senescence and organismal aging, and proposed the multifaceted regulatory characteristics under senescent and nonsenescent contexts. Next, we outlined the research progress of mTOR inhibitors in the field of antiaging and discussed future prospects and challenges. It is our pleasure if this review article could provide meaningful information for our readers and call forth more investigations working on this topic.

Emerging roles of senolytics/senomorphics in HIV-related co-morbidities

Human immunodeficiency virus (HIV) is known to cause cellular senescence and inflammation among infected individuals. While the traditional antiretroviral therapies (ART) have allowed the once fatal infection to be managed effectively, the quality of life of HIV patients on prolonged ART use is still inferior. Most of these individuals suffer from life-threatening comorbidities like chronic obstructive pulmonary disease (COPD), pulmonary arterial hypertension (PAH), and diabetes, to name a few. Interestingly, cellular senescence is known to play a critical role in the pathophysiology of these comorbidities as well. It is therefore important to understand the role of cellular senescence in the disease progression and co-morbidity development in HIV-infected individuals. In this respect, use of senolytic/senomorphic drugs as combination therapy with ART would be beneficial for HIV patients. This review provides a critical analysis of the current literature to determine the potential and efficacy of using senolytics/senotherapeutics in managing HIV infection, latency, and associated co-morbidities in humans. The various classes of senolytics have been studied in detail to focus on their potential to combat against HIV infections and associated pathologies with advancing age.

Particulate matter 2.5 accelerates aging: Exploring cellular senescence and age-related diseases

Exposure to Particulate matter 2.5 (PM2.5) accelerates aging, causing declines in tissue and organ function, and leading to diseases such as cardiovascular, neurodegenerative, and musculoskeletal disorders. PM2.5 is a major environmental pollutant and an exogenous pathogen in air pollution that is now recognized as an accelerator of human aging and a predisposing factor for several age-related diseases. In this paper, we seek to elucidate the mechanisms by which PM2.5 induces cellular senescence, such as genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, and mitochondrial dysfunction, and age-related diseases. Our goal is to increase awareness among researchers within the field of the toxicity of environmental pollutants and to advocate for personal and public health initiatives to curb their production and enhance population protection. Through these endeavors, we aim to promote longevity and health in older adults.

Treatment of chronic obstructive pulmonary disease by traditional Chinese medicine Morin monomer regulated by autophagy

Background

Chronic obstructive pulmonary disease (COPD) is a frequently occurring disorder. The aim of this study is to explore the mechanism of traditional Chinese medicine Morin monomer in the treatment of COPD via regulating autophagy based on the long non-coding RNA (lncRNA) H19/microRNA (miR)-194-5p/Sirtuin (SIRT)1 signal axis.

Methods

The COPD rat model was constructed, and the lung tissues were collected. The pathological analysis was performed using hematoxylin-eosin (HE), Masson, and periodic acid-Schiff (PAS) staining. Autophagosomes were observed using transmission electron microscope. LncRNA H19, miR-194-5p, SIRT1 genes in the rat lung tissues were detected using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). The autophagy-related proteins including SIRT1, mammalian/mechanistic target of rapamycin (mTOR), phosphorylated (p)-mTOR, microtubule-associated protein light chain 3 (LC3), Beclin-1, autophagy-related (ATG)7, and p62 in each group were detected using Western blot.

Results

The rats in the control group had normal lung structure. Alveolar enlargement and destruction could be found in the rat lung tissues in the model group, accompanied with obvious infiltration of inflammatory cells, thickened bronchial walls, enlarged alveolar septum, collagen fibers deposition, and goblet cells proliferation. In comparison with the model group, Morin treatment relieved the lung injuries, which was optimized in the moderate- and high-dose groups. The number of autophagosomes in the lung tissues of the model rats was dramatically increased compared with the normal rats. However, the number of autophagosomes in each Morin treatment group was obviously less than that in the model group. LncRNA H19 and SIRT1 expression was significantly increased in the model group, and miR-194-5p was significantly decreased (P<0.05). Morin and 3-methyladenine (3-MA) could obviously reduce the lncRNA H19 and SIRT1 expression, and increase the miR-194-5p expression (P<0.05). Relative to control rats, ATG7, Beclin-1, LC3II/I and SIRT1 levels in the model group increased obviously, while the expression of p62, and p-mTOR/mTOR decreased (P<0.05). Morin treatment reduced the expression of ATG7, Beclin-1, SIRT1, LC3II/I significantly, and increased the p-mTOR/mTOR and p62 expression (P<0.05).

Conclusions

Morin decreased lncRNA H19 expression, resulting in upregulation of miR-194-5p expression, downregulation of SIRT1 expression, and increased of p-mTOR/mTOR expression. Furthermore, cell autophagy was inhibited, contributing to the COPD treatment.

Trehalose attenuates testicular aging by activating autophagy and improving mitochondrial quality

BACKGROUND

Reproductive aging can adversely affect male fertility and the health of offspring. The aging process is accompanied by impaired autophagy. Recent studies have shown that Trehalose plays an important role in the prevention of various diseases by regulating autophagy. However, the roles of Trehalose in testicular aging and reproductive decline remain to be clarified.

OBJECTIVE

The present study aimed to evaluate the protective effects of Trehalose on testes in an aging mouse model.

MATERIALS AND METHODS

In this study, an in vivo aging model in mice by administering D-galactose was established to explore the protective effect of Trehalose on testicular aging. We examined histological changes and related indicators of apoptosis, autophagy, mitochondrial biogenesis, and sperm quality.

RESULTS

D-galactose treatment induced oxidative stress, apoptosis, and impairment of autophagy of testicular cells in mouse testes. Trehalose administration significantly reduced germ cell apoptosis and DNA damage caused by D-galactose-induced oxidative stress. Notably, Trehalose activated autophagy activity and improved mitochondrial function in testicular cells. Furthermore, Trehalose treatment increased the expression level of the tight junction protein ZO-1, and accelerated clearance of damaged mitochondria in Sertoli cells, indicating that Trehalose ameliorated Sertoli cell function in D-galactose-induced aging testes.

DISCUSSION AND CONCLUSION

These findings suggest that Trehalose administration activated the autophagy activity in testicular cells and improved mitochondrial function, thereby effectively preventing testicular aging. Trehalose and its activated autophagy are crucial for preventing testicular aging, thus restoring autophagy activity by administering Trehalose could be a promising means to delay aging.

The cGAS-STING pathway in COPD: targeting its role and therapeutic potential

Chronic obstructive pulmonary disease(COPD) is a gradually worsening and fatal heterogeneous lung disease characterized by airflow limitation and increasingly decline in lung function. Currently, it is one of the leading causes of death worldwide. The consistent feature of COPD is airway inflammation. Several inflammatory factors are known to be involved in COPD pathogenesis; however, anti-inflammatory therapy is not the first-line treatment for COPD. Although bronchodilators, corticosteroids and roflumilast could improve airflow and control symptoms, they could not reverse the disease. The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway plays an important novel role in the immune system and has been confirmed to be a key mediator of inflammation during infection, cellular stress, and tissue damage. Recent studies have emphasized that abnormal activation of cGAS-STING contributes to COPD, providing a direction for new treatments that we urgently need to develop. Here, we focused on the cGAS-STING pathway, providing insight into its molecular mechanism and summarizing the current knowledge on the role of the cGAS-STING pathway in COPD. Moreover, we explored antagonists of cGAS and STING to identify potential therapeutic strategies for COPD that target the cGAS-STING pathway.

Immunosenescence and Inflammation in Chronic Obstructive Pulmonary Disease: A Systematic Review

Background/Objectives: Chronic Obstructive Pulmonary Disease (COPD) is a disease of premature aging, characterized by airflow limitations in the lungs and systemic chronic inflammation. This systematic review aimed to provide a systematic overview of immunosenescence and inflammation in Chronic Obstructive Pulmonary Disease (COPD). Methods: The PubMed, Science Direct, Scopus, Cochrane Library, and Web of Science databases were searched for studies on markers of immunosenescence. Observational studies comparing patients with COPD to individuals without disease were evaluated, considering the following markers: inflammation and senescence in COPD, naïve, memory, and CD28null T cells, and telomere length in leukocytes. Results: A total of 15 studies were included, eight of which were rated as high quality. IL-6 production, telomere shortening, and the higher frequencies of CD28null T cells were more prominent findings in the COPD studies analyzed. Despite lung function severity being commonly investigated in the included studies, the importance of this clinical marker to immunosenescence remains inconclusive. Conclusions: The findings of this systematic review confirmed the presence of accelerated immunosenescence, in addition to systemic inflammation, in stable COPD patients. Further studies are necessary to more comprehensively evaluate the impact of immunosenescence on lung function in COPD.

Exosomes derived stem cells as a modern therapeutic approach for skin rejuvenation and hair regrowth

Background

The skin covers the surface of the body and acts as the first defense barrier against environmental damage. Exposure of the skin to environmental physical and chemical factors such as mechanical injuries, UV rays, air pollution, chemicals, etc. Leads to numerous damages to skin cells such as fibroblasts, keratinocytes, melanocytes, etc. The harmful effects of environmental factors on skin cells could lead to various skin diseases, chronic wounds, wrinkles, and skin aging. Hair is an essential part of the body, serving multiple functions such as regulating body temperature and protecting against external factors like dust (through eyelashes and eyebrows). It also reflects an individual's personality. Therefore, the need for new treatment methods for skin diseases and lesions and at the same time preserving the youth, freshness, and beauty of the skin has been highly noticed by experts. Exosomes are nanovesicles derived from cells that contain various biological compounds such as lipids, proteins, nucleic acids, and carbohydrates. They are secreted by a variety of mammalian cells and even different plants. Exosomes are of great interest as a new therapeutic approach due to their stability, ability to be transported throughout the body, paracrine and endocrine effects, as well as the ability to carry various compounds and drugs to target cells.

Aim

In this review, we have discussed the characteristics of exosomes, their cellular sources, and their therapeutic effects on wrinkles, skin aging, and rejuvenation and hair regrowth.

Musculoskeletal crosstalk in chronic obstructive pulmonary disease and comorbidities: Emerging roles and therapeutic potentials

Chronic Obstructive Pulmonary Disease (COPD) is a multifaceted respiratory disorder characterized by progressive airflow limitation and systemic implications. It has become increasingly apparent that COPD exerts its influence far beyond the respiratory system, extending its impact to various organ systems. Among these, the musculoskeletal system emerges as a central player in both the pathogenesis and management of COPD and its associated comorbidities. Muscle dysfunction and osteoporosis are prevalent musculoskeletal disorders in COPD patients, leading to a substantial decline in exercise capacity and overall health. These manifestations are influenced by systemic inflammation, oxidative stress, and hormonal imbalances, all hallmarks of COPD. Recent research has uncovered an intricate interplay between COPD and musculoskeletal comorbidities, suggesting that muscle and bone tissues may cross-communicate through the release of signalling molecules, known as "myokines" and "osteokines". We explored this dynamic relationship, with a particular focus on the role of the immune system in mediating the cross-communication between muscle and bone in COPD. Moreover, we delved into existing and emerging therapeutic strategies for managing musculoskeletal disorders in COPD. It underscores the development of personalized treatment approaches that target both the respiratory and musculoskeletal aspects of COPD, offering the promise of improved well-being and quality of life for individuals grappling with this complex condition. This comprehensive review underscores the significance of recognizing the profound impact of COPD on the musculoskeletal system and its comorbidities. By unravelling the intricate connections between these systems and exploring innovative treatment avenues, we can aspire to enhance the overall care and outcomes for COPD patients, ultimately offering hope for improved health and well-being.

The role of extracellular vesicles in COPD and potential clinical value

Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung disease and a major health burden worldwide. Extracellular vesicles (EVs) are nanosized vesicles which possess a lipid bilayer structure that are secreted by various cells. They contain a variety of bioactive substances, which can regulate various physiological and pathological processes and are closely related to the development of diseases. Recently, EVs have emerged as a novel tool for intercellular crosstalk, which plays an essential role in COPD development. This paper reviews the role of EVs in the development of COPD and their potential clinical value, in order to provide a reference for further research on COPD.

PSAT1 promotes autophagy to resist insufficient autophagy caused by cigarette smoke extract in human airway epithelial cells

The inhaling of cigarette smoke (CS) causes damage to airway epithelial cells, which is related to chronic obstructive pulmonary disease (COPD). It has been established that CS induces autophagy, but it is still unclear whether excessive or insufficient autophagy results in cell death. This study discovered that CS significantly elevates PSAT1 expression in bronchial epithelial cells. Further studies using autophagy inhibitor, RNA interference, RT-qPCR, western blot, and CCK-8 assay in 16-HBE cells have confirmed that autophagy is temporarily initiated by cigarette smoke extract (CSE), but insufficient autophagy leads to cell death. PSAT1 induced by CSE promotes autophagy and resists insufficient autophagy caused by CSE through Akt/mTOR pathway in human bronchial epithelial cells, playing a protective role.

Advances in the investigation of the role of autophagy in the etiology of chronic obstructive pulmonary disease: A review

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory illness. It arises from emphysema and chronic bronchitis and is characterized by progressive and irreversible airflow limitation and chronic inflammation of the lungs, which eventually progresses to pulmonary hypertension, chronic pulmonary heart disease and respiratory failure. Autophagy is a highly conserved cellular homeostasis maintenance mechanism that involves the transport of damaged organelles and proteins to lysosomes for destruction. Dysregulation of autophagy is one of the pathogenic mechanisms of many diseases and is strongly associated with the development of COPD, although the precise mechanisms are unknown. In this paper, we focus on macroautophagy, a type of autophagy that has been thoroughly studied, and describe the characteristics, processes, regulatory pathways, and functions of autophagy, and discuss its relationship with COPD from the perspectives of inflammation, emphysema, mucus hypersecretion, cilia structure and function, airway remodeling, vascular remodeling, and bacterial infections, with a view to searching for the therapeutic targets of COPD from the perspective of autophagy, which is hoped to be helpful for the clinical treatment.

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

Background

There is increasing evidence of autophagy activation in COPD, but its role is complex and probably regulated through cell type-specific mechanisms. This study aims to investigate the autophagic process at multiple levels within the respiratory system, using different methods to clarify conflicting results reported so far.

Methods

This cross-sectional study was performed on bronchial biopsies and peripheral lung samples obtained from COPD patients (30 and 12 per sample type, respectively) and healthy controls (25 and 22 per sample type, respectively), divided by smoking history. Subjects were matched for age and smoking history. We analysed some of the most important proteins involved in autophagosome formation, such as LC3 and p62, as well as some molecules essential for lysosome function, such as lysosome-associated membrane protein 1 (LAMP1). Immunohistochemistry was used to assess the autophagic process in both sample types. ELISA and transcriptomic analysis were performed on lung samples.

Results

We found increased autophagic stimulus in smoking subjects, regardless of respiratory function. This was revealed by immunohistochemistry through a significant increase in LC3 (p<0.01) and LAMP1 (p<0.01) in small airway bronchiolar epithelium, alveolar septa and alveolar macrophages. Similar results were obtained in bronchial biopsy epithelium by evaluating LC3B (p<0.05), also increased in homogenate lung tissue using ELISA (p<0.05). Patients with COPD, unlike the others, showed an increase in p62 by ELISA (p<0.05). No differences were found in transcriptomics analysis.

Conclusions

Different techniques, applied at post-transcriptional level, confirm that cigarette smoke stimulates autophagy at multiple levels inside the respiratory system, and that autophagy failure may characterise COPD.

Impact of air pollution on cardiovascular aging

The world population is aging rapidly, and by some estimates, the number of people older than 60 will double in the next 30 years. With the increase in life expectancy, adverse effects of environmental exposures start playing a more prominent role in human health. Air pollution is now widely considered the most detrimental of all environmental risk factors, with some studies estimating that almost 20% of all deaths globally could be attributed to poor air quality. Cardiovascular diseases are the leading cause of death worldwide and will continue to account for the most significant percentage of non-communicable disease burden. Cardiovascular aging with defined pathomechanisms is a major trigger of cardiovascular disease in old age. Effects of environmental risk factors on cardiovascular aging should be considered in order to increase the health span and reduce the burden of cardiovascular disease in older populations. In this review, we explore the effects of air pollution on cardiovascular aging, from the molecular mechanisms to cardiovascular manifestations of aging and, finally, the age-related cardiovascular outcomes. We also explore the distinction between the effects of air pollution on healthy aging and disease progression. Future efforts should focus on extending the health span rather than the lifespan.

Peroxinredoxin 6 reduction accelerates cigarette smoke extract‑induced senescence by regulating autophagy in BEAS‑2B cells

Cigarette smoke (CS)-induced accelerated senescence and insufficient autophagy has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Peroxiredoxin (PRDX) 6 is a protein with prevalent antioxidant capacity. Previous studies indicate that PRDX6 could activate autophagy and alleviate senescence in other diseases. The present study investigated whether PRDX6-regulated autophagy was involved in the regulation of CS extract (CSE)-induced BEAS-2B cell senescence via the knockdown of PRDX6 expression. Furthermore, the present study evaluated the mRNA levels of PRDX6, autophagy and senescence-associated genes in the small airway epithelium from patients with COPD by analyzing the GSE20257 dataset from the Gene Expression Omnibus database. The results demonstrated that CSE reduced PRDX6 expression levels and transiently induced the activation of autophagy, followed by the accelerated senescence of BEAS-2B cells. Knockdown of PRDX6 induced autophagy degradation and accelerated senescence in CSE-treated BEAS-2B cells. Furthermore, autophagy inhibition by 3-Methyladenine increased P16 and P21 expression levels, while autophagy activation by rapamycin reduced P16 and P21 expression levels in CSE-treated BEAS-2B cells. The GSE20257 dataset revealed that patients with COPD had lower PRDX6, sirtuin (SIRT) 1 and SIRT6 mRNA levels, and higher P62 and P16 mRNA levels compared with non-smokers. P62 mRNA was significantly correlated with P16, P21 and SIRT1, which indicated that insufficient autophagic clearance of damaged proteins could be involved in accelerated cell senescence in COPD. In conclusion, the present study demonstrated a novel protective role for PRDX6 in COPD. Furthermore, a reduction in PRDX6 could accelerate senescence by inducing autophagy impairment in CSE-treated BEAS-2B cells.

Airway Epithelium Senescence as a Driving Mechanism in COPD Pathogenesis

Cellular senescence is a state of permanent cell cycle arrest triggered by various intrinsic and extrinsic stressors. Cellular senescence results in impaired tissue repair and remodeling, loss of physiological integrity, organ dysfunction, and changes in the secretome. The systemic accumulation of senescence cells has been observed in many age-related diseases. Likewise, cellular senescence has been implicated as a risk factor and driving mechanism in chronic obstructive pulmonary disease (COPD) pathogenesis. Airway epithelium exhibits hallmark features of senescence in COPD including activation of the p53/p21WAF1/CIP1 and p16INK4A/RB pathways, leading to cell cycle arrest. Airway epithelial senescent cells secrete an array of inflammatory mediators, the so-called senescence-associated secretory phenotype (SASP), leading to a persistent low-grade chronic inflammation in COPD. SASP further promotes senescence in an autocrine and paracrine manner, potentially contributing to the onset and progression of COPD. In addition, cellular senescence in COPD airway epithelium is associated with telomere dysfunction, DNA damage, and oxidative stress. This review discusses the potential mechanisms of airway epithelial cell senescence in COPD, the impact of cellular senescence on the development and severity of the disease, and highlights potential targets for modulating cellular senescence in airway epithelium as a potential therapeutic approach in COPD.

Mechanisms of airway epithelial injury and abnormal repair in asthma and COPD

The airway epithelium comprises of different cell types and acts as a physical barrier preventing pathogens, including inhaled particles and microbes, from entering the lungs. Goblet cells and submucosal glands produce mucus that traps pathogens, which are expelled from the respiratory tract by ciliated cells. Basal cells act as progenitor cells, differentiating into different epithelial cell types, to maintain homeostasis following injury. Adherens and tight junctions between cells maintain the epithelial barrier function and regulate the movement of molecules across it. In this review we discuss how abnormal epithelial structure and function, caused by chronic injury and abnormal repair, drives airway disease and specifically asthma and chronic obstructive pulmonary disease (COPD). In both diseases, inhaled allergens, pollutants and microbes disrupt junctional complexes and promote cell death, impairing the barrier function and leading to increased penetration of pathogens and a constant airway immune response. In asthma, the inflammatory response precipitates the epithelial injury and drives abnormal basal cell differentiation. This leads to reduced ciliated cells, goblet cell hyperplasia and increased epithelial mesenchymal transition, which contribute to impaired mucociliary clearance and airway remodelling. In COPD, chronic oxidative stress and inflammation trigger premature epithelial cell senescence, which contributes to loss of epithelial integrity and airway inflammation and remodelling. Increased numbers of basal cells showing deregulated differentiation, contributes to ciliary dysfunction and mucous hyperproduction in COPD airways. Defective antioxidant, antiviral and damage repair mechanisms, possibly due to genetic or epigenetic factors, may confer susceptibility to airway epithelial dysfunction in these diseases. The current evidence suggests that a constant cycle of injury and abnormal repair of the epithelium drives chronic airway inflammation and remodelling in asthma and COPD. Mechanistic understanding of injury susceptibility and damage response may lead to improved therapies for these diseases.

GSPE attenuates CSE-induced lung inflammation and emphysema by regulating autophagy via the reactive oxygen species/TFEB signaling pathway

Cigarette smoke can enhance reactive oxygen species (ROS) production in inflammatory and epithelial cells. Subsequently, ROS enhance autophagy-induced inflammation due to alveolar macrophages (AMs), the primary source of cytokines implicated in chronic obstructive pulmonary disease (COPD) pathogenesis. Therefore, we hypothesized that grape seed proanthocyanidin extract (GSPE), an effective antioxidant, could inhibit emphysema and airway inflammation by ameliorating cigarette smoke extract (CSE)-induced autophagy via suppressing oxidative stress in macrophages. We observed that GSPE significantly attenuated histological changes observed in CSE-induced emphysema and airway inflammation in the lungs of mice. Moreover, GSPE ameliorated lung inflammation by reducing the number of cells, macrophages, and neutrophils and the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels measured in bronchioloalveolar lavage fluid. ROS levels increased after CSE instillation and significantly decreased with in vitro GSPE treatment. GSPE decreased transcription factor EB (TFEB) oxidation by reducing ROS, inhibiting TFEB nuclear translocation. Furthermore, GSPE inhibited ROS-induced autophagy in RAW 264.7 cells, bone marrow-derived macrophages, and AMs. Inhibiting autophagy through GSPE treatment diminishes CSE-induced lung inflammation by inhibiting the NLRP3 inflammasome. This study demonstrates that GSPE can ameliorate CSE-induced inflammation and emphysema via autophagy-induced NLRP3 inflammasome regulation through the ROS/TFEB signaling pathway in a COPD mouse model.

Drugs against metabolic diseases as potential senotherapeutics for aging-related respiratory diseases

Recent advances in aging research have provided novel insights for the development of senotherapy, which utilizes cellular senescence as a therapeutic target. Cellular senescence is involved in the pathogenesis of various chronic diseases, including metabolic and respiratory diseases. Senotherapy is a potential therapeutic strategy for aging-related pathologies. Senotherapy can be classified into senolytics (induce cell death in senescent cells) and senomorphics (ameliorate the adverse effects of senescent cells represented by the senescence-associated secretory phenotype). Although the precise mechanism has not been elucidated, various drugs against metabolic diseases may function as senotherapeutics, which has piqued the interest of the scientific community. Cellular senescence is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), which are aging-related respiratory diseases. Large-scale observational studies have reported that several drugs, such as metformin and statins, may ameliorate the progression of COPD and IPF. Recent studies have reported that drugs against metabolic diseases may exert a pharmacological effect on aging-related respiratory diseases that can be different from their original effect on metabolic diseases. However, high non-physiological concentrations are needed to determine the efficacy of these drugs under experimental conditions. Inhalation therapy may increase the local concentration of drugs in the lungs without exerting systemic adverse effects. Thus, the clinical application of drugs against metabolic diseases, especially through an inhalation treatment modality, can be a novel therapeutic approach for aging-related respiratory diseases. This review summarizes and discusses accumulating evidence on the mechanisms of aging, as well as on cellular senescence and senotherapeutics, including drugs against metabolic diseases. We propose a developmental strategy for a senotherapeutic approach for aging-related respiratory diseases with a special focus on COPD and IPF.

Role of autophagy in lung diseases and ageing

The lungs face ongoing chemical, mechanical, biological, immunological and xenobiotic stresses over a lifetime. Advancing age progressively impairs lung function. Autophagy is a "housekeeping" survival strategy involved in numerous physiological and pathological processes in all eukaryotic cells. Autophagic activity decreases with age in several species, whereas its basic activity extends throughout the lifespan of most animals. Dysregulation of autophagy has been proven to be closely related to the pathogenesis of several ageing-related pulmonary diseases. This review summarises the role of autophagy in the pathogenesis of pulmonary diseases associated with or occurring in the context of ageing, including acute lung injury, chronic obstructive pulmonary disease, asthma and pulmonary fibrosis, and describes its potential as a therapeutic target.

Targeting the Autophagy-Lysosome Pathway in a Pathophysiologically Relevant Murine Model of Reversible Heart Failure

The key biological "drivers" that are responsible for reverse left ventricle (LV) remodeling are not well understood. To gain an understanding of the role of the autophagy-lysosome pathway in reverse LV remodeling, we used a pathophysiologically relevant murine model of reversible heart failure, wherein pressure overload by transaortic constriction superimposed on acute coronary artery (myocardial infarction) ligation leads to a heart failure phenotype that is reversible by hemodynamic unloading. Here we show transaortic constriction + myocardial infarction leads to decreased flux through the autophagy-lysosome pathway with the accumulation of damaged proteins and organelles in cardiac myocytes, whereas hemodynamic unloading is associated with restoration of autophagic flux to normal levels with incomplete removal of damaged proteins and organelles in myocytes and reverse LV remodeling, suggesting that restoration of flux is insufficient to completely restore myocardial proteostasis. Enhancing autophagic flux with adeno-associated virus 9-transcription factor EB resulted in more favorable reverse LV remodeling in mice that had undergone hemodynamic unloading, whereas overexpressing transcription factor EB in mice that have not undergone hemodynamic unloading leads to increased mortality, suggesting that the therapeutic outcomes of enhancing autophagic flux will depend on the conditions in which flux is being studied.

Effective-component compatibility of Bufei Yishen formula III ameliorated COPD by improving airway epithelial cell senescence by promoting mitophagy via the NRF2/PINK1 pathway

Background

Effective-component compatibility of Bufei Yishen formula III (ECC-BYF III) demonstrates positive effects on stable chronic obstructive pulmonary disease (COPD).

Purpose

To investigate the mechanisms of ECC-BYF III on COPD rats from the aspect of airway epithelial cell senescence.

Methods

COPD model rats (Sprague-Dawley rat) were treated with ECC-BYF III for 8 weeks, and the efficacy was evaluated. Cigarette smoke extract (CSE)-induced senescence model of airway epithelial cells was treated with ECC-BYF III, and related enzymes and proteins involved in oxidative stress and mitophagy were detected.

Results

ECC-BYF III markedly rescued pulmonary function and histopathological changes, which might be associated with the amelioration of lung senescence, including the reduction of malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and matrix metalloproteinase (MMP)-9 levels, increase of the level in total superoxide dismutase (T-SOD), and decease in the p21 level in the airways. Furthermore, ECC-BYF III suppressed p16 and p21 expressions and senescence-associated β-galactosidase (SA-β-Gal) in CSE-induced airway epithelial cells. Moreover, ECC-BYF III upregulated mitophagy-related proteins, including the co-localizations of TOM20 and LC3B, PINK1 and PARK2, and improved mitochondrial function by upregulating mitochondrial mitofusin (MFN)2 and reducing dynamin-related protein 1 (DRP1) expression. ECC-BYF III enhanced the activities of T-SOD and GSH-PX by up-regulating NRF2, thus inhibiting oxidative stress. After intervention with NRF2 inhibitor, the regulation effects of ECC-BYF III on oxidative stress, mitophagy and senescence in airway epithelial cells were significantly suppressed.

Conclusions

ECC-BYF III exerts beneficial effects on COPD rats by ameliorating airway epithelial cell senescence, which is mediated by inhibiting oxidative stress and subsequently enhancing mitophagy through the activation of NRF2 signaling.

Smoking-Associated Exposure of Human Primary Bronchial Epithelial Cells to Aldehydes: Impact on Molecular Mechanisms Controlling Mitochondrial Content and Function

Chronic obstructive pulmonary disease (COPD) is a devastating lung disease primarily caused by exposure to cigarette smoke (CS). During the pyrolysis and combustion of tobacco, reactive aldehydes such as acetaldehyde, acrolein, and formaldehyde are formed, which are known to be involved in respiratory toxicity. Although CS-induced mitochondrial dysfunction has been implicated in the pathophysiology of COPD, the role of aldehydes therein is incompletely understood. To investigate this, we used a physiologically relevant in vitro exposure model of differentiated human primary bronchial epithelial cells (PBEC) exposed to CS (one cigarette) or a mixture of acetaldehyde, acrolein, and formaldehyde (at relevant concentrations of one cigarette) or air, in a continuous flow system using a puff-like exposure protocol. Exposure of PBEC to CS resulted in elevated IL-8 cytokine and mRNA levels, increased abundance of constituents associated with autophagy, decreased protein levels of molecules associated with the mitophagy machinery, and alterations in the abundance of regulators of mitochondrial biogenesis. Furthermore, decreased transcript levels of basal epithelial cell marker KRT5 were reported after CS exposure. Only parts of these changes were replicated in PBEC upon exposure to a combination of acetaldehyde, acrolein, and formaldehyde. More specifically, aldehydes decreased MAP1LC3A mRNA (autophagy) and BNIP3 protein (mitophagy) and increased ESRRA protein (mitochondrial biogenesis). These data suggest that other compounds in addition to aldehydes in CS contribute to CS-induced dysregulation of constituents controlling mitochondrial content and function in airway epithelial cells.

The macrophage senescence hypothesis: the role of poor heat shock response in pulmonary inflammation and endothelial dysfunction following chronic exposure to air pollution

INTRODUCTION

Cardiovascular diseases (CVD) have been associated with high exposure to fine particulate air pollutants (PM_2.5). Alveolar macrophages are the first defense against inhaled particles. As soon as they phagocytize the particles, they reach an inflammatory phenotype, which affects the surrounding cells and associates with CVD. Not coincidentally, CVD are marked by a depleted heat shock response (HSR), defined by a deficit in inducing 70-kDa heat shock protein (HSP70) expression during stressful conditions. HSP70 is a powerful anti-inflammatory chaperone, whose reduced levels trigger a pro-inflammatory milieu, cellular senescence, and a senescence-associated secretory phenotype (SASP). However, whether macrophage senescence is the main mechanism by which PM_2.5 propagates low-grade inflammation remains unclear.

OBJECTIVE AND DESIGN

In this article, we review evidence supporting that chronic exposure to PM_2.5 depletes HSR and determines the ability to solve the initial stress.

RESULTS AND DISCUSSION

When exposed to PM_2.5, macrophages increase the production of reactive oxygen species, which activate nuclear factor-kappa B (NF-κB). NF-κB is naturally a pro-inflammatory factor that drives prostaglandin E2 (PGE2) synthesis and causes fever. PGE2 can be converted into prostaglandin A2, a powerful inducer of HSR. Therefore, when transiently activated, NF-κB can trigger the anti-inflammatory response through negative feedback, by inducing HSP70 expression. However, when chronically activated, NF-κB heads a set of pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, unfolded protein response, inflammasome activation, and apoptosis. During chronic exposure to PM_2.5, cells cannot properly express sirtuin-1 or activate heat shock factor-1 (HSF-1), which delays the resolution phase of inflammation. Since alveolar macrophages are the first immune defense against PM_2.5, we suppose that the pollutant impairs HSR and, consequently, induces cellular senescence. Accordingly, senescent macrophages change its secretory phenotype to a more inflammatory one, known as SASP. Finally, macrophages' SASP would propagate the systemic inflammation, leading to endothelial dysfunction and atherosclerosis.

The interplay between oxidative stress and autophagy in chronic obstructive pulmonary disease

Autophagy is a highly conserved process that is indispensable for cell survival, embryonic development, and tissue homeostasis. Activation of autophagy protects cells against oxidative stress and is a major adaptive response to injury. When autophagy is dysregulated by factors such as smoking, environmental insults and aging, it can lead to enhanced formation of aggressors and production of reactive oxygen species (ROS), resulting in oxidative stress and oxidative damage to cells. ROS activates autophagy, which in turn promotes cell adaptation and reduces oxidative damage by degrading and circulating damaged macromolecules and dysfunctional cell organelles. The cellular response triggered by oxidative stress includes changes in signaling pathways that ultimately regulate autophagy. Chronic obstructive pulmonary disease (COPD) is the most common lung disease among the elderly worldwide, with a high mortality rate. As an induced response to oxidative stress, autophagy plays an important role in the pathogenesis of COPD. This review discusses the regulation of oxidative stress and autophagy in COPD, and aims to provide new avenues for future research on target-specific treatments for COPD.

From the divergence of senescent cell fates to mechanisms and selectivity of senolytic drugs

Senescence is a cellular stress response that involves prolonged cell survival, a quasi-irreversible proliferative arrest and a modification of the transcriptome that sometimes includes inflammatory gene expression. Senescent cells are resistant to apoptosis, and if not eliminated by the immune system they may accumulate and lead to chronic inflammation and tissue dysfunction. Senolytics are drugs that selectively induce cell death in senescent cells, but not in proliferative or quiescent cells, and they have proved a viable therapeutic approach in multiple mouse models of pathologies in which senescence is implicated. As the catalogue of senolytic compounds is expanding, novel survival strategies of senescent cells are uncovered, and variations in sensitivity to senolysis between different types of senescent cells emerge. We propose herein a mechanistic classification of senolytic drugs, based on the level at which they target senescent cells: directly disrupting BH3 protein networks that are reorganized upon senescence induction; downregulating survival-associated pathways essential to senescent cells; or modulating homeostatic processes whose regulation is challenged in senescence. With this approach, we highlight the important diversity of senescent cells in terms of physiology and pathways of apoptosis suppression, and we describe possible avenues for the development of more selective senolytics.

The Multifaceted Roles of Autophagy in Infectious, Obstructive, and Malignant Airway Diseases

Autophagy is a highly conserved dynamic process by which cells deliver their contents to lysosomes for degradation, thus ensuring cell homeostasis. In response to environmental stress, the induction of autophagy is crucial for cell survival. The dysregulation of this degradative process has been implicated in a wide range of pathologies, including lung diseases, representing a relevant potential target with significant clinical outcomes. During lung disease progression and infections, autophagy may exert both protective and harmful effects on cells. In this review, we will explore the implications of autophagy and its selective forms in several lung infections, such as SARS-CoV-2, Respiratory Syncytial Virus (RSV) and Mycobacterium tuberculosis (Mtb) infections, and different lung diseases such as Cystic Fibrosis (CF), Chronic Obstructive Pulmonary Disease (COPD), and Malignant Mesothelioma (MM).

Revealing the pathogenic and ageing-related mechanisms of the enigmatic idiopathic pulmonary fibrosis (and chronic obstructive pulmonary disease)

PURPOSE OF REVIEW

Growing evidence suggests that ageing-associated alterations occur in both idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD). Here, we review the most recent literature on dysregulated ageing pathways in IPF and COPD and discuss how they may contribute to disease pathogenesis.

RECENT FINDINGS

Recent studies have shown that alveolar epithelial type II (ATII) cells undergo premature senescence under stress and that senescent ATII cells promote lung fibrogenesis. Some studies have explored the role of mitochondrial dysfunction in IPF. They have provided evidence that dysfunctional mitochondria are important contributors to fibrogenesis through release of damaged DNA and excessive formation of reactive oxygen species, whereas restoration of mitochondrial homeostasis may attenuate lung fibrosis. Insufficient autophagy has been shown to promote epithelial-to-mesenchymal transition and aberrant epithelial-fibroblast crosstalk, suggesting that autophagy augmentation may represent a potential therapeutic strategy. A number of studies have also explored the role of cellular senescence, mitochondrial homeostasis and autophagy in COPD.

SUMMARY

Several ageing mechanisms are dysregulated in the lungs of patients with IPF and COPD, although how they contribute to disease development and progression remains elusive. Genetic or pharmacologic attenuation of senescence-related pathways and elimination of senescent cells may represent a promising therapeutic strategy.

LAM Cells as Potential Drivers of Senescence in Lymphangioleiomyomatosis Microenvironment

Senescence is a stress-response process characterized by the irreversible inhibition of cell proliferation, associated to the acquisition of a senescence-associated secretory phenotype (SASP), that may drive pathological conditions. Lymphangioleiomyomatosis (LAM) is a rare disease in which LAM cells, featuring the hyperactivation of the mammalian Target of Rapamycin Complex 1 (mTORC1) for the absence of tuberin expression, cause the disruption of the lung parenchyma. Considering that LAM cells secrete SASP factors and that mTOR is also a driver of senescence, we deepened the contribution of senescence in LAM cell phenotype. We firstly demonstrated that human primary tuberin-deficient LAM cells (LAM/TSC cells) have senescent features depending on mTOR hyperactivation, since their high positivity to SA-β galactosidase and to phospho-histone H2A.X are reduced by inducing tuberin expression and by inhibiting mTOR with rapamycin. Then, we demonstrated the capability of LAM/TSC cells to induce senescence. Indeed, primary lung fibroblasts (PLFs) grown in LAM/TSC conditioned medium increased the positivity to SA-β galactosidase and to phospho-histone H2A.X, as well as p21^WAF1/CIP1 expression, and enhanced the mRNA expression and the secretion of the SASP component IL-8. Taken together, these data make senescence a novel field of study to understand LAM development and progression.

Regulation of endoplasmic reticulum stress by hesperetin: Focus on antitumor and cytoprotective effects

BACKGROUND

Cancer is still an all-times issue due to a large and even increasing number of deaths. Impaired genes regulating cell proliferation and apoptosis are targets for the development of novel cancer treatments.

HYPOTHESIS

Increased transcription of NADPH oxidase activator (NOXA), Bcl2-like11 (BIM), BH3-only proteins and p53 unregulated apoptosis modulator (PUMA) is caused by the imbalance between pro- and anti-apoptotic Bcl-2 proteins due to endoplasmic reticulum (ER) stress. The membranous network of ER is present in all eukaryotic cells. ER stress facilitates the interaction between Bax and PUMA, triggering the release of cytochrome C. As a main intracellular organelle, ER is responsible for translocation as well as post-translation modification and protein folding.

RESULTS

Hesperetin is a cytoprotective flavonone, which acts against ER stress and protects from cell damage induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Hesperetin inhibits lipid peroxidation induced by Fe²⁺ and l-ascorbic acid in rat brain homogenates.

CONCLUSION

This review deals with the anticancer effects of hesperetin regarding the regulation of ER stress as a principal mechanism in the pathogenesis of tumors.

Autophagy in asthma and chronic obstructive pulmonary disease

Autophagy (or macroautophagy) is a key cellular process that removes damaged molecules (particularly proteins) and subcellular organelles to maintain cellular homeostasis. There is growing evidence that abnormalities in autophagy may contribute to the pathogenesis of many chronic diseases, including asthma and chronic obstructive pulmonary disease (COPD). In asthma, increased autophagy plays a role in promoting type 2 immune responses and eosinophilic inflammation, whereas decreased autophagy may be important in neutrophilic asthma. Acute exposure to cigarette smoke may activate autophagy, resulting in ciliary dysfunction and death of airway epithelial cells, whereas in stable COPD most studies have demonstrated an impairment in autophagy, with reduced autophagic flux and accumulation of abnormal mitochondria (defective mitophagy) and linked to cellular senescence. Autophagy may be increased or decreased in different cell types and depending on the cellular environment, making it difficult to target autophagy therapeutically. Several existing drugs may activate autophagy, including rapamycin, metformin, carbamazepine, cardiac glycosides and statins, whereas others, such as chloroquine, inhibit this process. However, these drugs are nonspecific and more selective drugs are now in development, which may prove useful as novel agents to treat asthma and COPD in the future.

The role of retinoid-related orphan receptor-α in cigarette smoke-induced autophagic response

BACKGROUND

Retinoid-related orphan receptor-α (RORα) and autophagy dysregulation are involved in the pathophysiology of chronic obstructive pulmonary disease (COPD), but little is known regarding their association. We investigated the role of RORα in COPD-related autophagy.

METHODS

The lung tissues and cells from a mouse model were analyzed for autophagy markers by using western blot analysis and transmission electron microscopy.

RESULTS

Cigarette smoke increased the LC3-II level and decreased the p62 level in whole lung homogenates of a chronic cigarette smoking mouse model. Although cigarette smoke did not affect the levels of p62 in Staggerer mutant mice (RORαsg/sg), the baseline expression levels of p62 were significantly higher than those in wild type (WT) mice. Autophagy was induced by cigarette smoke extract (CSE) in Beas-2B cells and in primary fibroblasts from WT mice. In contrast, fibroblasts from RORαsg/sg mice failed to show CSE-induced autophagy and exhibited fewer autophagosomes, lower LC3-II levels, and higher p62 levels than fibroblasts from WT mice. Damage-regulated autophagy modulator (DRAM), a p53-induced modulator of autophagy, was expressed at significantly lower levels in the fibroblasts from RORαsg/sg mice than in those from WT mice. DRAM knockdown using siRNA in Beas-2B cells inhibited CSE-induced autophagy and cell death. Furthermore, RORα co-immunoprecipitated with p53 and the interaction increased p53 reporter gene activity.

CONCLUSIONS

Our findings suggest that RORα promotes autophagy and contributes to COPD pathogenesis via regulation of the RORα-p53-DRAM pathway.

Emerging role of exosomes in the pathology of chronic obstructive pulmonary diseases; destructive and therapeutic properties

Chronic obstructive pulmonary disease (COPD) is known as the third leading cause of human death globally. Enhanced chronic inflammation and pathological remodeling are the main consequences of COPD, leading to decreased life span. Histological and molecular investigations revealed that prominent immune cell infiltration and release of several cytokines contribute to progressive chronic remodeling. Recent investigations have revealed that exosomes belonging to extracellular vesicles are involved in the pathogenesis of COPD. It has been elucidated that exosomes secreted from immune cells are eligible to carry numerous pro-inflammatory factors exacerbating the pathological conditions. Here, in this review article, we have summarized various and reliable information about the negative role of immune cell-derived exosomes in the remodeling of pulmonary tissue and airways destruction in COPD patients.

Autophagy Induced by BCL2-Related ceRNA Network Participates in the Occurrence of COPD

Purpose

Chronic obstructive pulmonary disease (COPD) is a predominant cause of mortality worldwide. Autophagy, which depends on a lysosomal degradation pathway, plays an essential role in the occurrence of COPD. The aim of our study was to identify the potential function of autophagy and construct a BCL2-related competing endogenous RNA (ceRNA) network that induces autophagy in COPD.

Methods

Blood sample data from GSE31568, GSE24709, and GSE61741 were collected from the Gene Expression Omnibus (GEO) database. Differentially expressed miRNAs in COPD and controls were identified via GEO2R. Transcription factors were obtained from FunRich. DIANA, miRDB, miRTarBase, and TargetScan were used to predict target genes of miRNAs. Autophagy genes were collected from the Human Autophagy Database (HADb). The GSE151052 dataset was used to identify autophagy-related differentially expressed genes in tissues. Functional enrichment and protein–protein interaction (PPI) network analyses were conducted via Metascape and the STRING network. Spearman correlation analysis was used to analyze the relationship between autophagy-related differentially expressed genes and lung function. The BCL2-related ceRNA network was modeled by Cytoscape.

Results

We obtained 41 differentially expressed miRNAs and 10 significantly different transcription factors. We identified 19 autophagy-related differentially expressed genes that were significantly different (P<0.05) in tissue samples. The most significant enrichment in Metascape was an autophagy item, which further confirmed autophagy participation in the occurrence of COPD. PPI network analysis found four genes (BCL2, BECN1, MAPK8, and ITPR1), among which BCL2 was correlated with both FEV1/FVC and FEV1 prediction. Finally, the BCL2-related ceRNA network was constructed to clarify the interaction of RNAs and occurrence of autophagy, including 18 miRNAs and 65 lncRNAs.

Conclusion

We identified 19 autophagy-related differentially expressed genes that participated in COPD; among them, BCL2 was correlated with lung function, and a BCL2-related ceRNA network was constructed, which further revealed the potential mechanism of autophagy involvement in COPD.

Extracellular Vesicles as Central Mediators of COPD Pathophysiology

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous, smoking-related disease of significant global impact. The complex biology of COPD is ultimately driven by a few interrelated processes, including proteolytic tissue remodeling, innate immune inflammation, derangements of the host-pathogen response, aberrant cellular phenotype switching, and cellular senescence, among others. Each of these processes are engendered and perpetuated by cells modulating their environment or each other. Extracellular vesicles (EVs) are powerful effectors that allow cells to perform a diverse array of functions on both adjacent and distant tissues, and their pleiotropic nature is only beginning to be appreciated. As such, EVs are candidates to play major roles in these fundamental mechanisms of disease behind COPD. Furthermore, some such roles for EVs are already established, and EVs are implicated in significant aspects of COPD pathogenesis. Here, we discuss known and potential ways that EVs modulate the environment of their originating cells to contribute to the processes that underlie COPD.

Pathogenesis of COPD at the cellular and molecular level

Chronic inflammatory responses in the lung of patients with stable mild-to severe forms of COPD play a central role in the definition, comprehension and monitoring of the disease state. A better understanding of the COPD pathogenesis can't avoid a detailed knowledge of these inflammatory changes altering the functional health of the lung during the disease progression. We here summarize and discuss the role and principal functions of the inflammatory cells populating the large, small airways and lung parenchyma of patients with COPD of increasing severity in comparison with healthy control subjects: T and B lymphocytes, NK and Innate Lymphoid cells, macrophages, and neutrophils. The differential inflammatory distribution in large and small airways of patients is also discussed. Furthermore, relevant cellular mechanisms controlling the homeostasis and the "normal" balance of these inflammatory cells and of structural cells in the lung, such as autophagy, apoptosis, necroptosis and pyroptosis are as well presented and discussed in the context of the COPD severity.

Bronchial epithelial SIRT1 deficiency exacerbates cigarette smoke induced emphysema in mice through the FOXO3/PINK1 pathway

Purpose: Cellular senescence and mitochondrial fragmentation are thought to be crucial components of the cigarette smoke(CS)-induced responses that contribute to the chronic obstructive pulmonary disease (COPD) development as a result of accelerated premature aging of the lung. Although there have been a few reports on the role of sirtuin 1(SIRT1) in mitochondrial homeostasis, senescence and inflammation, whether SIRT1/FOXO3/PINK1 signaling mediated mitophagy ameliorates cellular senescence in COPD is still unclear. This study aimed to ascertain whether SIRT1 regulates cellular senescence via FOXO3/PINK1-mediated mitophagy in COPD. Methods: To investigate the effect of CS exposure and SIRT1 deficiency on mitophagy and senescence in the lung, a SIRT1 knockout(KO) mouse model was used. Airway resistance, cellular senescence mitochondrial injury, mitophagy, cellular architecture and protein expression levels in lung tissues, from SIRT1 KO and wild-type(WT) COPD model mice exposed to CS for 6 months were examined by western blotting, histochemistry, immunofluorescence and transmission electron microscopy(TEM). Results: In CS exposed mice, SIRT1 deficiency exacerbated airway resistance and cellular senescence, increased FOXO3 acetylation and decreased PINK1 protein levels and attenuated mitophagy. Mechanistically, the damaging effect of SIRT1 deficiency on lung tissue was attributed to increased FOXO3 acetylation and decreased PINK1 levels, and attenuated mitophagy. In vitro, mitochondrial damage and cellular sensitivity in response to CS exposure were more severe in control cells than in cells treated with aSIRT1 activator. SIRT1 activation SIRT1 activation decreased FOXO3 acetylation and increased the protein levels of PINK1 and enhanced mitophagy. Conclusion: These results demonstrated that the detrimental effects of SIRT1 deficiency on cell senescence associated with insufficient mitophagy, and involved the FOXO3/PINK1 signaling pathway.

Extracellular Release of Mitochondrial DNA: Triggered by Cigarette Smoke and Detected in COPD

Cigarette smoke (CS) is the most common risk factor for chronic obstructive pulmonary disease (COPD). The present study aimed to elucidate whether mtDNA is released upon CS exposure and is detected in the plasma of former smokers affected by COPD as a possible consequence of airway damage. We measured cell-free mtDNA (cf-mtDNA) and nuclear DNA (cf-nDNA) in COPD patient plasma and mouse serum with CS-induced emphysema. The plasma of patients with COPD and serum of mice with CS-induced emphysema showed increased cf-mtDNA levels. In cell culture, exposure to a sublethal dose of CSE decreased mitochondrial membrane potential, increased oxidative stress, dysregulated mitochondrial dynamics, and triggered mtDNA release in extracellular vesicles (EVs). Mitochondrial DNA release into EVs occurred concomitantly with increased expression of markers that associate with DNA damage responses, including DNase III, DNA-sensing receptors (cGAS and NLRP3), proinflammatory cytokines (IL-1β, IL-6, IL-8, IL-18, and CXCL2), and markers of senescence (p16 and p21); the majority of the responses are also triggered by cytosolic DNA delivery in vitro. Exposure to a lethal CSE dose preferentially induced mtDNA and nDNA release in the cell debris. Collectively, the results of this study associate markers of mitochondrial stress, inflammation, and senescence with mtDNA release induced by CSE exposure. Because high cf-mtDNA is detected in the plasma of COPD patients and serum of mice with emphysema, our findings support the future study of cf-mtDNA as a marker of mitochondrial stress in response to CS exposure and COPD pathology.

Structural and Functional Changes and Possible Molecular Mechanisms in Aged Skin

Skin aging is a complex process influenced by intrinsic and extrinsic factors. Together, these factors affect the structure and function of the epidermis and dermis. Histologically, aging skin typically shows epidermal atrophy due to decreased cell numbers. The dermis of aged skin shows decreased numbers of mast cells and fibroblasts. Fibroblast senescence contributes to skin aging by secreting a senescence-associated secretory phenotype, which decreases proliferation by impairing the release of essential growth factors and enhancing degradation of the extracellular matrix through activation of matrix metalloproteinases (MMPs). Several molecular mechanisms affect skin aging including telomere shortening, oxidative stress and MMP, cytokines, autophagic control, microRNAs, and the microbiome. Accumulating evidence on the molecular mechanisms of skin aging has provided clinicians with a wide range of therapeutic targets for treating aging skin.

Klotho as Potential Autophagy Regulator and Therapeutic Target

The protein Klotho can significantly delay aging, so it has attracted widespread attention. Abnormal downregulation of Klotho has been detected in several aging-related diseases, such as Alzheimer’s disease, kidney injury, cancer, chronic obstructive pulmonary disease (COPD), vascular disease, muscular dystrophy and diabetes. Conversely, many exogenous and endogenous factors, several drugs, lifestyle changes and genetic manipulations were reported to exert therapeutic effects through increasing Klotho expression. In recent years, Klotho has been identified as a potential autophagy regulator. How Klotho may contribute to reversing the effects of aging and disease became clearer when it was linked to autophagy, the process in which eukaryotic cells clear away dysfunctional proteins and damaged organelles: the abovementioned diseases involve abnormal autophagy. Interestingly, growing evidence indicates that Klotho plays a dual role as inducer or inhibitor of autophagy in different physiological or pathological conditions through its influence on IGF-1/PI3K/Akt/mTOR signaling pathway, Beclin 1 expression and activity, as well as aldosterone level, which can help restore autophagy to beneficial levels. The present review examines the role of Klotho in regulating autophagy in Alzheimer’s disease, kidney injury, cancer, COPD, vascular disease, muscular dystrophy and diabetes. Targeting Klotho may provide a new perspective for preventing and treating aging-related diseases.

The Link between Circadian Clock Genes and Autophagy in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a progressive respiratory disease, is characterized by the alveolar epithelium injury and persistent airway inflammation. It is documented that oscillation and dysregulated expression of circadian clock genes, like Bmal1, Per1, and Per2, involved in COPD pathogenies, including chronic inflammation and imbalanced autophagy level, and targeting the associations of circadian rhythm and autophagy is promising strategies in the management and treatment of COPD. Herein, we reviewed the mechanisms of the circadian clock and the unbalance of the autophagic level in COPD, as well as the link between the two, so as to provide further theoretical bases for the study on the pathogenesis of COPD.

Cellular senescence-an aging hallmark in chronic obstructive pulmonary disease pathogenesis

Chronic obstructive pulmonary disease (COPD),¹ a representative aging-related pulmonary disorder, is mainly caused by cigarette smoke (CS) exposure. Age is one of the most important risk factors for COPD development, and increased cellular senescence in tissues and organs is a component of aging. CS exposure can induce cellular senescence, as characterized by irreversible growth arrest and aberrant cytokine secretion of the senescence-associated secretory phenotype; thus, accumulation of senescent cells is widely implicated in COPD pathogenesis. CS-induced oxidative modifications to cellular components may be causally linked to accelerated cellular senescence, especially during accumulation of damaged macromolecules. Autophagy is a conserved mechanism whereby cytoplasmic components are sent for lysosomal degradation to maintain proteostasis. Autophagy diminishes with age, and loss of proteostasis is one of the hallmarks of aging. We have reported the involvement of insufficient autophagy in regulating CS-induced cellular senescence with respect to COPD pathogenesis. However, the role of autophagy in COPD pathogenesis can vary based on levels of cell stress and type of selective autophagy because excessive activation of autophagy can be responsible for inducing regulated cell death. Senotherapies targeting cellular senescence may be effective COPD treatments. Autophagy activation could be a promising sonotherapeutic approach, but the optimal modality of autophagy activation should be examined in future studies.

Role of chaperone-mediated autophagy in the pathophysiology including pulmonary disorders

Autophagy is a highly conserved mechanism of delivering cytoplasmic components for lysosomal degradation. Among the three major autophagic pathways, chaperone-mediated autophagy (CMA) is primarily characterized by its selective nature of protein degradation, which is mediated by heat shock cognate 71 kDa protein (HSC70: also known as HSPA8) recognition of the KFERQ peptide motif in target proteins. Lysosome-associated membrane protein type 2A (LAMP2A) is responsible for substrate binding and internalization to lysosomes, and thus, the lysosomal expression level of LAMP2A is a rate-limiting factor for CMA. Recent advances have uncovered not only physiological but also pathological role of CMA in multiple organs, including neurodegenerative disorders, kidney diseases, liver diseases, heart diseases, and cancers through the accumulation of unwanted proteins or increased degradation of target proteins with concomitant metabolic alterations resulting from CMA malfunction. With respect to pulmonary disorders, the involvement of CMA has been demonstrated in lung cancer and chronic obstructive pulmonary disease (COPD) pathogenesis through regulating apoptosis. Further understanding of CMA machinery may shed light on the molecular mechanisms of refractory disorders and lead to novel treatment modalities through CMA modulation.

Increased LHX9 expression in alveolar epithelial type 2 cells of patients with chronic obstructive pulmonary disease

BACKGROUND

Alveolar epithelial type 2 (AT2) cells serve as stem cells in alveolar epithelium and are assumed to lose their stem cell function in the lungs of chronic obstructive pulmonary disease (COPD). Although we previously reported that LHX9 mRNA expression was up-regulated in AT2 cells of COPD lung tissues, it is yet to be elucidated how LHX9 is associated with the vulnerability of AT2 cells in COPD.

METHODS

AT2 cells were isolated from lung tissues of 10 non-COPD subjects and 11 COPD patients. LHX9 mRNA expression was determined by quantitative RT-PCR. To identify up-stream molecules, an alveolar epithelial cell line A549 was exposed to pro-inflammatory cytokines in vitro. siRNA-mediated Lhx9 knockdown was performed to determine how Lhx9 affected the cellular viability and the cell-division cycle.

RESULTS

LHX9 mRNA expression was increased in AT2 cells from COPD lung tissues, compared to those from non-COPD tissues. The airflow obstruction was independently correlated with the increase in LHX9 expression. Among several pro-inflammatory cytokines, interferon-γ was a strong inducer of LHX9 expression in A549 cells. Lhx9 was involved in the increased susceptibility to serum starvation-induced death of A549 cells.

CONCLUSIONS

Our data suggest that IFN-γ predominantly increases the LHX9 expression which enhances the susceptibility to cell death. Considering the independent association of the increased LHX9 expression in AT2 cells with airflow obstruction, the IFN-γ-Lhx9 axis might contribute to the vulnerability of AT2 cells in the lungs of COPD patients.