Senescence In Chronic Obstructive Pulmonary Disease Research Articles

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.

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.

Secreted phospholipase A2 XIIA triggers a mitochondrial damage-induced senescence in chronic obstructive pulmonary disease fibroblasts

RationaleLung fibroblast senescence is involved in the pathophysiology of chronic obstructive pulmonary disease (COPD). However, the mechanisms underlining this phenomenon are still poorly understood. Secreted phospholipases (sPLA2, a subclass of phospholipases) are secreted by senescent cells and can in turn induce senescence. However, their role in fibroblasts senescence in COPD is unknown. ObjectivesThe aim of this study was to analyze the role of sPLA2 in pulmonary fibroblast senescence. MethodsFibroblasts were isolated from patients with COPD and control subjects, and senescence markers and inflammatory profile was analyzed. sPLA2 levels were quantified in serum of COPD and controls. Main resultsIn comparison with non-smokers and smoker controls, senescent lung COPD fibroblasts exhibited a higher mRNA and protein expression of the sPLA2 isoform XIIA and of syndecan 4 (one of its receptors). sPLA2 XIIA induced in turn senescence of non-senescent pulmonary fibroblasts via a pathway involving consecutively syndecan 4, activation of MAPK and p-serine 727 STAT-3, increased mitochondrial ROS production, and activation of AMPK/p53. This pathway was associated with a specific inflammatory secretome (IL-10, IL-12 and TNFα), globally suggesting occurrence of a mitochondrial damage-induced senescence. COPD fibroblasts were more susceptible to this sPLA2 XIIA effect than cells from controls subjects. sPLA2 XIIA levels were significantly higher in serum from COPD patients as compared to controls. ConclusionsPLA2 XIIA is involved in senescence in COPD and could be a potential target to dampen this process.

Clearance of senescent cells reverts the cigarette smoke-induced lung senescence and airspace enlargement in p16-3MR mice.

Cigarette smoke (CS) leads to increased oxidative stress, inflammation, and exaggerated senescence, which are involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). While the role of cellular senescence in COPD is known, it is not clear if the removal of senescent cells could alleviate the disease symptoms. To test this, we used the novel mouse model-p16-3MR, and studied the effect of ganciclovir (GCV)-mediated removal of senescent cells after chronic CS (3 months) and environmental tobacco smoke (ETS) (6 months) exposure to CS. Our results showed the reversal of CS-induced cellular senescence on the clearance of p16+ senesced cells by GCV treatment. Interestingly, the clearance of p16+ senescent cells via GCV led to a decrease in the neutrophil counts in the BALF of GCV-treated CS-exposed p16-3MR mice, as well as reversal of CS-mediated airspace enlargement in p16-3MR mice. Mice exposed to low dose ETS caused insignificant changes in the SA-β-Gal+ senescent cells and airspace enlargement. Overall, our data provideevidence for the role of lung cellular senescence on smoke exposure and clearance of senescent cells in p16-3MR mice in the reversal of COPD/emphysema pathology with a possibility of senolytics as therapeutic interventions in COPD.

Bufei Yishen Formula Inhibits the Cell Senescence in COPD by Up-Regulating the ZNF263 and Klotho Expression.

Bufei Yishen formula (BYF) is an effective prescription for the clinical treatment of chronic obstructive pulmonary disease (COPD). However, the molecular mechanism by which it exerts its pharmacological effects remains to be explored. The human bronchial cell line BEAS-2B was treated with cigarette smoke extract (CSE). Cellular senescence markers were detected by Western blot and ELISA. Potential transcription factor of klotho was predicted using JASPAR and USCS databases. CSE induced cellular senescence with intracellular accumulation of cellular senescence biomarkers (p16, p21 and p27) and increased secretion of senescence-related secretory phenotypic (SASP) factors (IL-6, IL-8, and CCL3). In contrast, BYF treatment inhibited CSE-induced cellular senescence. CSE suppressed the transcription, expression and secretion of klotho, whereas BYF treatment rescued its transcription, expression and secretion. CSE downregulated the protein level of ZNF263, whereas BYF treatment rescued the expression of ZNF263. Furthermore, ZNF263-overexpressing BEAS-2B cells could inhibit CSE-induced cellular senescence and SASP factor secretion by upregulating the expression of klotho. This study revealed a novel pharmacological mechanism by which BYF alleviates clinical symptoms of COPD patients, and regulating ZNF263 and klotho expression may be beneficial to the treatment and prevention of COPD.

Gene polymorphisms associated with heterogeneity and senescence characteristics of sarcopenia in chronic obstructive pulmonary disease.

Sarcopenia, or loss of skeletal muscle mass and decreased contractile strength, contributes to morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). The severity of sarcopenia in COPD is variable, and there are limited data to explain phenotype heterogeneity. Others have shown that COPD patients with sarcopenia have several hallmarks of cellular senescence, a potential mechanism of primary (age-related) sarcopenia. We tested if genetic contributors explain the variability in sarcopenic phenotype and accelerated senescence in COPD. To identify gene variants [single nucleotide polymorphisms (SNPs)] associated with sarcopenia in COPD, we performed a genome-wide association study (GWAS) of fat free mass index (FFMI) in 32 426 non-Hispanic White (NHW) UK Biobank participants with COPD. Several SNPs within the fat mass and obesity-associated (FTO) gene were associated with sarcopenia that were validated in an independent COPDGene cohort (n=3656). Leucocyte telomere length quantified in the UK Biobank cohort was used as a marker of senescence. Experimental validation was done by genetic depletion of FTO in murine skeletal myotubes exposed to prolonged intermittent hypoxia or chronic hypoxia because hypoxia contributes to sarcopenia in COPD. Molecular biomarkers for senescence were also quantified with FTO depletion in murine myotubes. Multiple SNPs located in the FTO gene were associated with sarcopenia in addition to novel SNPs both within and in proximity to the gene AC090771.2, which transcribes long non-coding RNA (lncRNA). To replicate our findings, we performed a GWAS of FFMI in NHW subjects from COPDGene. The SNP most significantly associated with FFMI was on chromosome (chr) 16, rs1558902A>T in the FTO gene (β=0.151, SE=0.021, P=1.40×10-12 for UK Biobank |β=0.220, SE=0.041, P=9.99×10-8 for COPDGene) and chr 18 SNP rs11664369C>T nearest to the AC090771.2 gene (β=0.129, SE=0.024, P=4.64×10-8 for UK Biobank |β=0.203, SE=0.045, P=6.38×10-6 for COPDGene). Lower handgrip strength, a measure of muscle strength, but not FFMI was associated with reduced telomere length in the UK Biobank. Experimentally, in vitro knockdown of FTO lowered myotube diameter and induced a senescence-associated molecular phenotype, which was worsened by prolonged intermittent hypoxia and chronic hypoxia. Genetic polymorphisms of FTO and AC090771.2 were associated with sarcopenia in COPD in independent cohorts. Knockdown of FTO in murine myotubes caused a molecular phenotype consistent with senescence that was exacerbated by hypoxia, a common condition in COPD. Genetic variation may interact with hypoxia and contribute to variable severity of sarcopenia and skeletal muscle molecular senescence phenotype in 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.

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.

Phospholipase A2 receptor 1 promotes lung cell senescence and emphysema in obstructive lung disease.

Cell senescence is a key process in age-associated dysfunction and diseases, notably chronic obstructive pulmonary disease (COPD). We previously identified phospholipase A2 receptor 1 (PLA2R1) as a positive regulator of cell senescence acting via Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling. Its role in pathology, however, remains unknown. Here, we assessed PLA2R1-induced senescence in COPD and lung emphysema pathogenesis. We assessed cell senescence in lungs and cultured lung cells from patients with COPD and controls subjected to PLA2R1 knockdown, PLA2R1 gene transduction and treatment with the JAK1/2 inhibitor ruxolitinib. To assess whether PLA2R1 upregulation caused lung lesions, we developed transgenic mice overexpressing PLA2R1 (PLA2R1-TG) and intratracheally injected wild-type mice with a lentiviral vector carrying the Pla2r1 gene (LV-PLA2R1 mice). We found that PLA2R1 was overexpressed in various cell types exhibiting senescence characteristics in COPD lungs. PLA2R1 knockdown extended the population doubling capacity of these cells and inhibited their pro-inflammatory senescence-associated secretory phenotype (SASP). PLA2R1-mediated cell senescence in COPD was largely reversed by treatment with the potent JAK1/2 inhibitor ruxolitinib. Five-month-old PLA2R1-TG mice exhibited lung cell senescence, and developed lung emphysema and lung fibrosis together with pulmonary hypertension. Treatment with ruxolitinib induced reversal of lung emphysema and fibrosis. LV-PLA2R1-treated mice developed lung emphysema within 4 weeks and this was markedly attenuated by concomitant ruxolitinib treatment. Our data support a major role for PLA2R1 activation in driving lung cell senescence and lung alterations in COPD. Targeting JAK1/2 may represent a promising therapeutic approach for COPD.

Lymphocyte senescence in COPD is associated with decreased sirtuin 1 expression in steroid resistant pro-inflammatory lymphocytes

Background:The class III NAD-dependent histone deacetylase (HDAC) sirtuin 1 (SIRT1) is an important regulator of senescence, aging, and inflammation. SIRT1de-acetylates chromatin histones, thereby silencing inflammatory gene transcription. We have reported increased steroid-resistant senescent pro-inflammatory CD28nullCD8+ T cells in patients with chronic obstructive pulmonary disease (COPD). We hypothesized that SIRT1 is reduced in these cells in COPD, and that treatment with SIRT1 activators (resveratrol, curcumin) and agents preventing NAD depletion (theophylline) would upregulate SIRT1 and reduce pro-inflammatory cytokine expression in these steroid-resistant cells.Methods:Blood was collected from n = 10 COPD and n = 10 aged-matched controls. Expression of CD28, SIRT1, and pro-inflammatory cytokines was determined in CD8+ and CD8– T and natural killer T (NKT)-like cells cultured in the presence of ±1 µM prednisolone, ±5 mg/L theophylline, ±1 µM curcumin, ±25 µM resveratrol, using flow cytometry and immunofluorescence.Results:There was an increase in the percentage of CD28nullCD8+ T and NKT-like cells in COPD patients compared with controls. Decreased SIRT1 expression was identified in CD28nullCD8+T and NKT-like cells compared with CD28+ counterparts from both patients and controls (e.g. CD28null 11 ± 3% versus CD28+ 57 ± 9%). Loss of SIRT1 was associated with increased production of IFNγ and TNFα, steroid resistance, and disease severity. SIRT1 expression was upregulated in the presence of all drugs and was associated with a decrease in steroid resistance and IFNγ and TNFα production by CD28nullCD8+T and NKT-like cells. The presence of the SIRT1 inhibitor, EX-527 negated [by 92 ± 12% (median ± SEM)] the effect of the SIRT1 activator SRT720 on the percentage of CD8+ T cells producing IFNγ and TNFα.Conclusions:Steroid resistance in pro-inflammatory CD28nullCD8+ T and NKT-like cells is associated with decreased SIRT1 expression. Treatment with prednisolone, in combination with theophylline, curcumin or resveratrol increases SIRT1 expression, restores steroid sensitivity, and inhibits pro-inflammatory cytokine production from these cells and may reduce systemic inflammation in COPD. The reviews of this paper are available via the supplemental material section.

MTOR pathway activation drives lung cell senescence and emphysema.

Chronic obstructive pulmonary disease (COPD) is a highly prevalent and devastating condition for which no curative treatment is available. Exaggerated lung cell senescence may be a major pathogenic factor. Here, we investigated the potential role for mTOR signaling in lung cell senescence and alterations in COPD using lung tissue and derived cultured cells from patients with COPD and from age- and sex-matched control smokers. Cell senescence in COPD was linked to mTOR activation, and mTOR inhibition by low-dose rapamycin prevented cell senescence and inhibited the proinflammatory senescence-associated secretory phenotype. To explore whether mTOR activation was a causal pathogenic factor, we developed transgenic mice exhibiting mTOR overactivity in lung vascular cells or alveolar epithelial cells. In this model, mTOR activation was sufficient to induce lung cell senescence and to mimic COPD lung alterations, with the rapid development of lung emphysema, pulmonary hypertension, and inflammation. These findings support a causal relationship between mTOR activation, lung cell senescence, and lung alterations in COPD, thereby identifying the mTOR pathway as a potentially new therapeutic target in COPD.

Senescence in COPD and Its Comorbidities.

Chronic obstructive pulmonary disease (COPD) is regarded as a disease of accelerated lung aging. This affliction shows all of the hallmarks of aging, including telomere shortening, cellular senescence, activation of PI3 kinase-mTOR signaling, impaired autophagy, mitochondrial dysfunction, stem cell exhaustion, epigenetic changes, abnormal microRNA profiles, immunosenescence, and a low-grade chronic inflammation (inflammaging). Many of these pathways are driven by chronic exogenous and endogenous oxidative stress. There is also a reduction in antiaging molecules, such as sirtuins and Klotho, which further accelerate the aging process. COPD is associated with several comorbidities (multimorbidity), such as cardiovascular and metabolic diseases, that share the same pathways of accelerated aging. Understanding these mechanisms has helped identify several novel therapeutic targets, and several drugs and dietary interventions are now in development to treat multimorbidity.

27-Hydroxycholesterol accelerates cellular senescence in human lung resident cells.

Cellular senescence is reportedly involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). We previously showed that 27-hydroxycholesterol (27-OHC) is elevated in the airways of COPD patients compared with those in healthy subjects. The aim of this study was to investigate whether lung fibroblasts of COPD patients are senescent and to determine the effects of 27-OHC on senescence of lung resident cells, including fibroblasts and airway epithelial cells. Localization of senescence-associated proteins and sterol 27-hydroxylase was investigated in the lungs of COPD patients by immunohistochemical staining. To evaluate whether 27-OHC accelerates cellular senescence, lung resident cells were exposed to 27-OHC. Senescence markers and fibroblast-mediated tissue repair were investigated in the 27-OHC-treated cells. Expression of senescence-associated proteins was significantly enhanced in lung fibroblasts of COPD patients. Similarly, expression of sterol 27-hydroxylase was significantly upregulated in lung fibroblasts and alveolar macrophages in these patients. Treatment with the concentration of 27-OHC detected in COPD airways significantly augmented expression of senescence-associated proteins and senescence-associated β-galactosidase activity, and delayed cell growth through the prostaglandin E2-reactive nitrogen species pathway. The 27-OHC-treated fibroblasts impaired tissue repair function. Fibroblasts from lungs of COPD patients showed accelerated senescence and were more susceptible to 27-OHC-induced cellular senescence compared with those of healthy subjects. In conclusion, 27-OHC accelerates cellular senescence in lung resident cells and may play a pivotal role in cellular senescence in COPD.

Telomere length in chronic obstructive pulmonary disease

Abstract Background Telomere length (TL) is considered a biomarker of cellular aging. Chronic obstructive pulmonary disease (COPD) is found to be associated with premature aging and the senescence hypothesis is now accepted as a molecular pathway for COPD development. Purpose The aim of this study was to measure TL in COPD patients and to study its relation to demographic data, spirometric indices, and arterial blood gases parameters. Participants and methods We measured TL using quantitative PCR in 20 patients with severe to very severe COPD and 11 age-matched and sex-matched nonsmokers. Results TL was significantly shorter in COPD patients (P < 0.001). Among COPD patients, TL was significantly shorter in current smokers than ex-smokers. In COPD patients, TL was correlated positively with SpO2%, pH (P < 0.05), PaO2 (P < 0.01), FVC% (P < 0.05) and FEV1%, and FEF25–75% (P < 0.001) and not correlated with pack-year. The BODE (Body mass index, airflow Obstruction, Dyspnea, and Exercise capacity) index was correlated negatively with TL (P < 0.01); among BODE index parameters, the dyspnea score correlated negatively (P < 0.05) with TL. TL was shorter in very severe COPD than severe COPD (P < 0.001). Conclusion Our data support accelerated cellular senescence in COPD represented by shortening of TL; TL was correlated positively with airflow limitation and it may be related to impaired physical activities in COPD, which is a manifestation of the aging process.

Senescence of pulmonary vascular cells is related to overactivation of the mTOR signaling pathway in chronic obstructive pulmonary disease (COPD)

Background Telomere dysfunction and exaggerated lung cell senescence now appear as major pathological processes leading to lung alterations in COPD. Pulmonary vascular endothelial cells (P-ECs) and smooth muscle cells (PA-SMCs) derived from lungs of patients with COPD exhibit increased susceptibility to replicative senescence compared to controls. However, the mechanisms underlying lung cell senescence in COPD remain poorly understood. Recent studies suggest that cell senescence and aging occur in response to overactivation of the mammalian target of rapamycin (mTOR) signaling pathway. Methods To investigate whether lung cell senescence is related to overactivation of the mTOR signaling pathway in COPD, we studied lung specimens and derived cultured PA-SMCs and P-ECs from patients with COPD and age- and sex-matched control smokers. Results Marked activation of the mTOR-Akt signaling pathway was found in lungs from patients with COPD compared to controls, with a marked PTEN decrease and activation of mTOR complex 1 (mTORC1) substrates S6K and 4EBP and of mTORC2 substrates P-Akt 473 and GSK3, together with an increase in p21 protein levels. In-situ analysis of lung specimens revealed prominent P-Akt 473 , P-S6K, and P-GSK3 staining in PA-SMCs and P-ECs from patients with COPD compared to controls, most notably the cells exhibiting staining for p16 and p21. In cultured PA-SMCs from patients and controls that were subjected to repeated passages, the onset of replicative cell senescence was associated with similar alterations, including decreased PTEN and activation of mTORC1 and mTORC2 substrates. Cell exposure to low-dose rapamycin, which selectively inhibits mTORC1 but not mTORC2, delayed the early onset of senescence, increasing the cell-population doublings and decreasing the percentage of beta-galactosidase-positive cells; and suppressed the senescence-associated secretory phenotype associated with COPD. Cell exposure to sulforaphane, which stimulates nff2, or bortezomib, which inhibits the proteasome, did not alter or potentiated the cell senescence process. Conclusion These results show that the increased propensity of lung vascular cells to senescence in COPD is related to overactivation of the mTOR/Akt signaling pathway and can be suppressed by rapamycin treatment.

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

Tobacco smoke-induced accelerated cell senescence has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cell senescence is accompanied by the accumulation of damaged cellular components suggesting that in COPD, inhibition of autophagy may contribute to cell senescence. Here we look at whether autophagy contributes to cigarette smoke extract (CSE) - induced cell senescence of primary human bronchial epithelial cells (HBEC), and further evaluate p62 and ubiquitinated protein levels in lung homogenates from COPD patients. We demonstrate that CSE transiently induces activation of autophagy in HBEC, followed by accelerated cell senescence and concomitant accumulation of p62 and ubiquitinated proteins. Autophagy inhibition further enhanced accumulations of p62 and ubiquitinated proteins, resulting in increased senescence and senescence-associated secretory phenotype (SASP) with interleukin (IL)-8 secretion. Conversely, autophagy activation by Torin1, a mammalian target of rapamycin (mTOR inhibitor), suppressed accumulations of p62 and ubiquitinated proteins and inhibits cell senescence. Despite increased baseline activity, autophagy induction in response to CSE was significantly decreased in HBEC from COPD patients. Increased accumulations of p62 and ubiquitinated proteins were detected in lung homogenates from COPD patients. Insufficient autophagic clearance of damaged proteins, including ubiquitinated proteins, is involved in accelerated cell senescence in COPD, suggesting a novel protective role for autophagy in the tobacco smoke-induced senescence-associated lung disease, COPD.