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Diseases of accelerated aging often occur together (multimorbidity), and their prevalence is increasing, with high societal and health care costs. Chronic obstructive pulmonary disease (COPD) is one such condition, in which one half of patients exhibit ≥4 age-related diseases. Diseases of accelerated aging share common molecular pathways, which lead to the detrimental accumulation of senescent cells. These senescent cells no longer divide but release multiple inflammatory proteins, known as the senescence-associated secretory phenotype, which may perpetuate and speed disease. Here, we show that inhibiting miR-570-3p, which is increased in COPD cells, reverses cellular senescence by restoring the antiaging molecule sirtuin-1. MiR-570-3p is induced by oxidative stress in airway epithelial cells through p38 MAP kinase-c-Jun signaling and drives senescence by inhibiting sirtuin-1. Inhibition of elevated miR-570-3p in COPD small airway epithelial cells, using an antagomir, restores sirtuin-1 and suppresses markers of cellular senescence (p16INK4a, p21Waf1, and p27Kip1), thereby restoring cellular growth by allowing progression through the cell cycle. MiR-570-3p inhibition also suppresses the senescence-associated secretory phenotype (matrix metalloproteinases-2/9, C-X-C motif chemokine ligand 8, IL-1β, and IL-6). Collectively, these data suggest that inhibiting miR-570-3p rejuvenates cells via restoration of sirtuin-1, reducing many of the abnormalities associated with cellular senescence.—Baker, J. R., Vuppusetty, C., Colley, T., Hassibi, S., Fenwick, P. S., Donnelly, L. E., Ito, K., Barnes, P. J. MicroRNA-570 is a novel regulator of cellular senescence and inflammaging.

SIRT1 (silent information regulator 2 homolog 1) is a crucial cellular survival protein especially in oxidative stress environments, and has been thought to locate within the nuclei, but also known to shuttle between cytoplasm and nuclei in some cell types. Here, we show for the first time the dynamics of SIRT1 in the presence of single or concurrent cigarette smoke extract (CSE) exposure in human bronchial epithelial cells (HBEC). In BEAS-2B HBEC or primary HBEC, SIRT1 was localized predominantly in cytoplasm, and the CSE (3%) induced nuclear translocation of SIRT1 from cytoplasm in the presence of L-buthionine sulfoximine (an irreversible inhibitor of γ-glutamylcystein synthetase), mainly through the activation of phosphatidylinositol 3-kinase (PI3K) α subunit. This SIRT1 nuclear shuttling was associated with FOXO3a nuclear translocation and the strong induction of several anti-oxidant genes including superoxide dismutase (SOD) 2 and 3; therefore seemed to be an adaptive response. When BEAS-2B cells were pretreated with repeated exposure to a lower concentration of CSE (0.3%), the CSE-induced SIRT1 shuttling and resultant SOD2/3 mRNA induction were significantly impaired. Thus, this result offers a useful cell model to mimic the impaired anti-oxidant capacity in cigarette smoking-associated lung disease such as chronic obstructive pulmonary disease.

The phosphatidylinositol 3-kinase (PI3K) pathway is activated in chronic obstructive pulmonary disease (COPD), but the regulatory mechanisms for this pathway are yet to be elucidated. Our aim was to determine the expression and role of phosphatase and tensin homolog deleted from chromosome 10 (PTEN), a negative regulator of the PI3K pathway, in COPD. PTEN expression and activity were measured in the peripheral lung of COPD patients compared to smoking and non-smoking controls. The direct influence of cigarette smoke extract (CSE) on PTEN expression was assessed using primary lung epithelial cells and a cell line (BEAS-2B) in the presence or absence of L-buthionine-sulfoximine (BSO) to deplete intracellular glutathione. The impact of PTEN knock-down by RNA interference on cytokine production was also examined. In peripheral lung, PTEN protein was significantly decreased in patients with COPD compared to the subjects without COPD (p < 0.001), and positively correlated with the severity of air-flow obstruction (FEV1 % predicted; r = 0.50; p = 0.0012), although no difference was observed in PTEN activity. Conversely, phosphorylated Akt, as a marker of PI3K activation, showed a negative correlation with PTEN protein levels (r = -0.41; p = 0.0042). Both in primary bronchial epithelial cells and BEAS-2B cell line, CSE decreased PTEN protein, which was reversed by N-acetylcysteine treatment. PTEN knock-down potentiated Akt phosphorylation and enhanced production of pro-inflammatory cytokines, such as IL-6, CXCL8, CCL2 and CCL5. In conclusion, oxidative stress reduces PTEN protein levels, which may result in increased PI3K signaling and amplification of inflammation in COPD.

Background: The protein deacetylase sirtuin-1 (SIRT1) is an anti-aging molecule that is decreased in the lung from patients with chronic obstructive pulmonary disease (COPD). Recently, SIRT1 was reported to be detectable in serum, but serum SIRT1 levels have not yet been reported in patients with COPD. Methods: Serum SIRT1 was measured by Western blotting, and relative ratio of band density in samples against that of a positive control were calculated. Results: Several molecular sizes of SIRT1, including 120kDa (actual size) and fragments (102, 75kDa) were quantified by Western blotting. Among them, only the 120kDa serum SIRT1 (s120S) was significantly decreased in the patients with COPD compared to the control subjects without COPD (s120S ratio in healthy: 0.90±0.34, vs COPD: 0.68±0.24; p=0.014), and was positively correlated with airway obstruction (FEV1/ FVC; r=0.31; p=0.020) and its severity measured by FEV1 % predicted (r=0.29; p=0.029). Serum s120S also showed a positive correlation with body mass index (BMI; r=0.36; p=0.0077) and diffusing capacity of the lung per unit volume (KCO%; r=0.32; p=0.025). It was also significantly decreased with increasing severity of lung emphysema (r=-0.40, p=0.027) and with a clinical history of frequent COPD exacerbations (infrequent: 0.76±0.20 vs frequent: 0.56±0.26; p=0.027). SIRT1 was not detected in supernatant of A549 and primary epithelial cells in normal culture condition. Conclusions: Serum SIRT1 (s120S) was decreased in the patients with COPD, potentially as reflected by the reduced SIRT1 within cells as a result of oxidative stress, and might be a potential biomarkers for certain disease characteristics of COPD.