The Aging Lung

A deep learning approach to dysphagia-aspiration detecting algorithm through pre- and post-swallowing voice changes

Introduction

This study aimed to identify differences in voice characteristics and changes between patients with dysphagia-aspiration and healthy individuals using a deep learning model, with a focus on under-researched areas of pre- and post-swallowing voice changes in patients with dysphagia. We hypothesized that these variations may be due to weakened muscles and blocked airways in patients with dysphagia.

Methods

A prospective cohort study was conducted on 198 participants aged >40 years at the Seoul National University Bundang Hospital from October 2021 to February 2023. Pre- and post-swallowing voice data of the participants were converted to a 64-kbps mp3 format, and all voice data were trimmed to a length of 2 s. The data were divided for 10-fold cross-validation and stored in HDF5 format with anonymized IDs and labels for the normal and aspiration groups. During preprocessing, the data were converted to Mel spectrograms, and the EfficientAT model was modified using the final layer of MobileNetV3 to effectively detect voice changes and analyze pre- and post-swallowing voices. This enabled the model to probabilistically categorize new patient voices as normal or aspirated.

Results

In a study of the machine-learning model for aspiration detection, area under the receiver operating characteristic curve (AUC) values were analyzed across sexes under different configurations. The average AUC values for males ranged from 0.8117 to 0.8319, with the best performance achieved at a learning rate of 3.00e-5 and a batch size of 16. The average AUC values for females improved from 0.6975 to 0.7331, with the best performance observed at a learning rate of 5.00e-5 and a batch size of 32. As there were fewer female participants, a combined model was developed to maintain the sex balance. In the combined model, the average AUC values ranged from 0.7746 to 0.7997, and optimal performance was achieved at a learning rate of 3.00e-5 and a batch size of 16.

Conclusion

This study evaluated a voice analysis-based program to detect pre- and post-swallowing changes in patients with dysphagia, potentially aiding in real-time monitoring. Such a system can provide healthcare professionals with daily insights into the conditions of patients, allowing for personalized interventions.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT05149976.

Cellular senescence mediates hexavalent chromium-associated lung function decline: Insights from a structural equation Model

There is sufficient evidence suggesting that exposure to hexavalent chromium [Cr(VI)] can cause a decline in lung function and the onset of lung diseases. However, no studies have yet explored the underlying mechanisms of these effects from various perspectives such as systemic inflammation, oxidative stress, and cellular senescence, simultaneously. This cross-sectional study was conducted among 304 workers engaged in chromate production and processing in China. Urine was used for detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F2α (8-iso-PGF2α), while RNA and DNA extraction from peripheral blood cells was used for detection of mRNA, telomere length, and ribosomal DNA copy numbers (rDNA CNs). A 2.7-fold elevation in blood chromate (Cr) corresponded to a 7.86% (95% CI: 2.57%, 13.42%) rise in urinary 8-OHdG and a 4.14% (0.02%, 8.42%) increase in urinary 8-iso-PGF2α, indicating that exposure to chromates can cause oxidative stress. Furthermore, strong correlations emerged between blood Cr concentration and mRNA levels of P16, P21, TP53, and P15 in the cellular senescence pathway. Simultaneously, a 2.7-fold elevation in blood Cr associated with a -5.47% (-8.72%, -2.1%) change in telomere length, while rDNA CNs (5S, 5.8S, 18S, and 28S) changed by -3.91% (-7.99%, 0.34%), -9.4% (-15.73%, -2.6%), -8.06% (-14.01%, -1.69%), and -5.86% (-10.67%, -0.78%), respectively. Structural equation model highlighted that cellular senescence exerted significant indirect effects on Cr(VI)-associated lung function decline, with a mediation proportion of 23.3%. This study provided data supporting for 8-iso-PGF2α, telomere length, and rDNA CNs as novel biomarkers of chromate exposure, emphasizing the significant role of cellular senescence in the mechanism underlying chromate-induced lung function decline.

Assessment of pulmonary physiological changes caused by aging, cigarette smoking, and COPD with hyperpolarized 129Xe magnetic resonance

OBJECTIVE

To comprehensively assess the impact of aging, cigarette smoking, and chronic obstructive pulmonary disease (COPD) on pulmonary physiology using 129Xe MR.

METHODS

A total of 90 subjects were categorized into four groups, including healthy young (HY, n = 20), age-matched control (AMC, n = 20), asymptomatic smokers (AS, n = 28), and COPD patients (n = 22). 129Xe MR was utilized to obtain pulmonary physiological parameters, including ventilation defect percent (VDP), alveolar sleeve depth (h), apparent diffusion coefficient (ADC), total septal wall thickness (d), and ratio of xenon signal from red blood cells and interstitial tissue/plasma (RBC/TP).

RESULTS

Significant differences were found in the measured VDP (p = 0.035), h (p = 0.003), and RBC/TP (p = 0.003) between the HY and AMC groups. Compared with the AMC group, higher VDP (p = 0.020) and d (p = 0.048) were found in the AS group; higher VDP (p < 0.001), d (p < 0.001) and ADC (p < 0.001), and lower h (p < 0.001) and RBC/TP (p < 0.001) were found in the COPD group. Moreover, significant differences were also found in the measured VDP (p < 0.001), h (p < 0.001), ADC (p < 0.001), d (p = 0.008), and RBC/TP (p = 0.032) between the AS and COPD groups.

CONCLUSION

Our findings indicate that pulmonary structure and functional changes caused by aging, cigarette smoking, and COPD are various, and show a progressive deterioration with the accumulation of these risk factors, including cigarette smoking and COPD.

CLINICAL RELEVANCE STATEMENT

Pathophysiological changes can be difficult to comprehensively understand due to limitations in common techniques and multifactorial etiologies. 129Xe MRI can demonstrate structural and functional changes caused by several common factors and can be used to better understand patients' underlying pathology.

KEY POINTS

Standard techniques for assessing pathophysiological lung function changes, spirometry, and chest CT come with limitations. 129Xe MR demonstrated progressive deterioration with accumulation of the investigated risk factors, without these limitations. 129Xe MR can assess lung changes related to these risk factors to stage and evaluate the etiology of the disease.

Long-term trajectories of peak expiratory flow rate in older men and women show linear decline mainly determined by baseline levels

BACKGROUND

Peak expiratory flow rate (PEFR) predicts mortality and other negative health outcomes. However, little evidence exists on how PEFR changes with ageing and how trajectories of change differ among older people.

AIMS

To identify trajectories of PEFR in older men and women, and to study characteristics associated with these trajectories.

METHODS

Data from the Longitudinal Aging Study Amsterdam were used, an ongoing cohort study in a representative sample of Dutch older men and women. PEFR was assessed using the Mini-Wright peak flow meter across a 13-year follow-up in 991 men and 1107 women. Trajectories were analyzed using Latent Class Growth Analysis.

RESULTS

Mean age was 72.5 (SD 8.4) in men and 72.4 (SD 8.4) in women. In men, three declining trajectories were identified, i.e. high, intermediate and low, with prevalences of 30%, 46% and 24%, respectively. In women, two declining trajectories were identified, i.e. high and low, with prevalences of 62 and 38%. All trajectories showed linear decline and differed mostly with regard to their intercept. Significant differences between trajectories with regard to baseline demographic, health and lifestyle characteristics were observed, e.g., men and women in the low PEFR trajectory were older, had more chronic diseases, and were more often smoker.

DISCUSSION AND CONCLUSIONS

Trajectories in both men and women differ mainly in baseline level of PEFR and not in rate of decline over time. Therefore, one PEFR measurement might be sufficient to give an indication of the trajectory that an older adult is likely to follow.

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.

The impact of aging-induced gut microbiome dysbiosis on dendritic cells and lung diseases

Aging is an inevitable natural process that impacts every individual, and understanding its effect on the gut microbiome and dendritic cell (DC) functionality in elderly subjects is crucial. DCs are vital antigen-presenting cells (APCs) that orchestrate the immune response, maintaining immune tolerance to self-antigens and bridging innate and adaptive immunity. With aging, there is a shift toward nonspecific innate immunity, resulting in a decline in adaptive immune responses. This alteration raises significant concerns about managing the health of an elderly population. However, the precise impact of aging and microbiome changes on DC function and their implications in lung-associated diseases remain relatively understudied. To illuminate this subject, we will discuss recent advancements in understanding the connections between aging, gut dysbiosis, DCs, and lung diseases. Emphasizing the key concepts linking age-related gut microbiome changes and DC functions, we will focus on their relevance to overall health and immune response in elderly individuals. This article aims to improve our understanding of the intricate relationship between aging, gut microbiome, and DCs, potentially benefiting the management of age-associated diseases and promoting healthy aging.

Serum α-Klotho level, lung function, airflow obstruction and inflammatory markers in US adults

Background

α-Klotho is a pleiotropic protein that may have anti-oxidative and anti-inflammatory properties in the lung, but its role in airflow obstruction or lung function is largely unknown.

Methods

This was a cross-sectional study of 6046 adults aged 40-79 years in the US National Health and Nutrition Examination Survey (NHANES) 2007-2012. We used multivariable logistic or linear regression to examine the relation between serum α-Klotho level and airflow obstruction, defined as forced expiratory volume in 1 s (FEV1) <80% of predicted and FEV1/forced vital capacity (FVC) ratio <0.70; FEV1, FVC and FEV1/FVC as percentage of predicted; and inflammatory markers in blood (white blood cell count, eosinophils, neutrophils and C-reactive protein (CRP)).

Results

α-Klotho levels in the second to fourth quartiles (Q2-Q4) were associated with significantly decreased odds of airflow obstruction (adjusted OR for Q2-Q4 versus lowest quartile (Q1) 0.54 (95% CI 0.35-0.81)) in never-smokers and ex-smokers with <10 pack-years of smoking, but not in current smokers or ex-smokers with ≥10 pack-years of smoking. In all participants, each unit increment in log10-transformed α-Klotho level was significantly associated with 5.0% higher FEV1 % pred and 3.7% higher FVC % pred. Higher α-Klotho was also associated with lower eosinophils, neutrophils and CRP in participants both with and without airflow obstruction.

Conclusions

Higher serum α-Klotho is associated with lower inflammatory markers and higher lung function in adults with and without airflow obstruction, and with decreased odds of airflow obstruction in never-smokers and ex-smokers with <10 pack-years of smoking. Further studies are warranted to replicate our findings and evaluate underlying mechanisms.

Pharmacotherapies in Older Adults with COPD: Challenges and Opportunities

Older adults have a higher prevalence of chronic obstructive pulmonary disease (COPD), which will likely increase substantially in the coming decades owing to aging populations and increased long-term exposure to risk factors for this disease. COPD in older adults is characterized by low-grade chronic systemic inflammation, known as inflamm-aging. It contributes substantially to age-associated pulmonary changes that are clinically expressed by reduced lung function, poor health status, and limitations in activities of daily living. In addition, inflamm-aging has been associated with the onset of many comorbidities commonly encountered in COPD. Furthermore, physiologic changes that are often seen with aging can influence the optimal treatment of older patients with COPD. Therefore, variables such as pharmacokinetics, pharmacodynamics, polypharmacy, comorbidities, adverse drug responses, drug interactions, method of administration, and social and economic issues that impact nutrition and adherence to therapy must be carefully evaluated when prescribing medication to these patients because each of them alone or together may affect the outcome of treatment. Current COPD medications focus mainly on alleviating COPD-related symptoms, so alternative treatment approaches that target the disease progression are being investigated. Considering the importance of inflamm-aging, new anti-inflammatory molecules are being evaluated, focusing on inhibiting the recruitment and activation of inflammatory cells, blocking mediators of inflammation thought to be important in the recruitment or activation of these inflammatory cells or released by these cells. Potential therapies that may slow the aging processes by acting on cellular senescence, blocking the processes that cause it (senostatics), eliminating senescent cells (senolytics), or targeting the ongoing oxidative stress seen with aging need to be evaluated.

KRT5+/p63+ Stem Cells Undergo Senescence in the Human Lung with Pathological Aging

Adult lungs present high cellular plasticity against stress and injury, mobilizing stem/progenitor populations from conducting airways to maintain tissue homeostasis and gas exchange in alveolar spaces. With aging, pulmonary functional and structural deterioration occurs, mainly in pathological conditions, which is associated with impaired stem cell activity and increased senescence in mice. However, the impact of these processes underlying lung physiopathology in relation to aging has not been explored in humans. In this work, we analyzed stem cell (SOX2, p63, KRT5), senescence (p16^INK4A, p21^CIP, Lamin B1) and proliferative (Ki67) markers in lung samples from young and aged individuals, with and without pulmonary pathology. We identified a reduction in SOX2⁺ cells but not p63⁺ and KRT5⁺ basal cells in small airways with aging. In alveoli, we revealed the presence of triple SOX2⁺, p63⁺ and KRT5⁺ cells specifically in aged individuals diagnosed with pulmonary pathologies. Notably, p63⁺ and KRT5⁺ basal stem cells displayed colocalization with p16^INK4A and p21^CIP, as well as with low Lamin B1 staining in alveoli. Further studies revealed that senescence and proliferation markers were mutually exclusive in stem cells with a higher percentage colocalizing with senescence markers. These results provide new evidence of the activity of p63⁺/KRT5⁺ stem cells on human lung regeneration and point out that regeneration machinery in human lung is activated under stress due to aging, but fails to repair in pathological cases, as stem cells would likely become senescent.

Impact of aging on immune function in the pathogenesis of pulmonary diseases: potential for therapeutic targets

INTRODUCTION

Several immunological alterations that occur during pulmonary diseases often mimic alterations observed in the aged lung. From the molecular perspective, pulmonary diseases and aging partake in familiar mechanisms associated with significant dysregulation of the immune systems. Here, we summarized the findings of how aging alters immunity to respiratory conditions to identify age-impacted pathways and mechanisms that contribute to the development of pulmonary diseases.

AREAS COVERED

The current review examines the impact of age-related molecular alterations in the aged immune system during various lung diseases, such as COPD, IPF, Asthma, and alongside many others that could possibly improve on current therapeutic interventions. Moreover, our increased understanding of this phenomenon may play a primary role in shaping immunomodulatory strategies to boost outcomes in the elderly. Here, the authors present new insights into the context of lung-related diseases and describe the alterations in the functioning of immune cells during various pulmonary conditions altered with age.

EXPERT OPINION

The expert opinion provided the concepts on how aging alters immunity during pulmonary conditions, and suggests the associated mechanisms during the development of lung diseases. As a result, it becomes important to comprehend the complex mechanism of aging in the immune lung system.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Senotherapy for lung diseases

Increasing evidence suggests that there is acceleration of lung ageing in chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), with the accumulation of senescent cells in the lung. Senescent cells fail to repair tissue damage and release an array of inflammatory proteins, known as the senescence-associated secretory phenotype, which drive further senescence and disease progression. This suggests that targeting cellular senescence with senotherapies may treat the underlying disease process in COPD and IPF and thus reduce disease progression and mortality. Several existing or future drugs may inhibit the development of cellular senescence which is driven by chronic oxidative stress (senostatics), including inhibitors of PI3K-mTOR signalling pathways, antagomirs of critical microRNAs and novel antioxidants. Other drugs (senolytics) selectively remove senescent cells by promoting apoptosis. Clinical studies with senotherapies are already underway in chronic lung diseases.

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 cellular senescence in inflammatory lung diseases

Cellular senescence, a characteristic sign of aging, classically refers to permanent cell proliferation arrest and is a vital contributor to the pathogenesis of cancer and age-related illnesses. A lot of imperative scientific research has shown that senescent cell aggregation and the release of senescence-associated secretory phenotype (SASP) components can cause lung inflammatory diseases as well. In this study, the most recent scientific progress on cellular senescence and phenotypes was reviewed, including their impact on lung inflammation and the contributions of these findings to understanding the underlying mechanisms and clinical relevance of cell and developmental biology. Within a dozen pro-senescent stimuli, the irreparable DNA damage, oxidative stress, and telomere erosion are all crucial in the long-term accumulation of senescent cells, resulting in sustained inflammatory stress activation in the respiratory system. An emerging role for cellular senescence in inflammatory lung diseases was proposed in this review, followed by the identification of the main ambiguities, thus further understanding this event and the potential to control cellular senescence and pro-inflammatory response activation. In addition, novel therapeutic strategies for the modulation of cellular senescence that might help to attenuate inflammatory lung conditions and improve disease outcomes were also presented in this research.

Age-Related Clinical Characteristics, Inflammatory Features, Phenotypes, and Treatment Response in Asthma

BACKGROUND

Emerging evidence suggests that aging affects asthma outcomes, but the mechanism remains largely unexplored.

OBJECTIVE

To explore age-related clinical characteristics, inflammatory features, phenotypes, and treatment response in asthma.

METHODS

This was a prospective cohort study of asthmatic patients with a 12-month follow-up in a real-world setting. Clinical inflammatory and phenotypic characteristics, future risk for exacerbations, and treatment response were assessed across different age groups (young was defined as age 18 to 39 years; middle-aged, 40 to 64 years; and elderly, 65 years or older).

RESULTS

Compared with young (n = 106) and middle-aged (n = 179) asthmatic patients, elderly patients (n = 55) had worse airway obstruction, more comorbidities including chronic obstructive pulmonary disease and diabetes, less atopy, and lower levels of IgE and FeNO, and were more likely to have late-onset and fixed airflow obstruction asthma and a reduced risk for having type 2 profile asthma. Levels of IFN-gamma, IL-17A, and IL-8 in induced sputum were significantly increased in elderly asthmatic patients (all P < .05). Path analysis indicated that age directly and significantly led to future exacerbations in asthma, partially mediated by an upregulation of airway IFN-gamma. Moreover, elderly patients with asthma had a reduced treatment response (improvement in FEV₁ of 12% or greater, or 200 mL, and a reduction in Borg scores of 1 or greater) (adjusted odds ratio = 0.11; 95% CI, 0.02-0.52; and adjusted odds ratio = 0.12; 95% CI, 0.03-0.49, respectively).

CONCLUSIONS

This study confirms that asthma in the elderly population represents a specific phenotype and indicates that aging can influence asthma in terms of clinical characteristics, inflammatory features, exacerbations, and treatment response.

Detection of early-stage lung cancer in sputum using automated flow cytometry and machine learning

BACKGROUND

Low-dose spiral computed tomography (LDCT) may not lead to a clear treatment path when small to intermediate-sized lung nodules are identified. We have combined flow cytometry and machine learning to develop a sputum-based test (CyPath Lung) that can assist physicians in decision-making in such cases.

METHODS

Single cell suspensions prepared from induced sputum samples collected over three consecutive days were labeled with a viability dye to exclude dead cells, antibodies to distinguish cell types, and a porphyrin to label cancer-associated cells. The labeled cell suspension was run on a flow cytometer and the data collected. An analysis pipeline combining automated flow cytometry data processing with machine learning was developed to distinguish cancer from non-cancer samples from 150 patients at high risk of whom 28 had lung cancer. Flow data and patient features were evaluated to identify predictors of lung cancer. Random training and test sets were chosen to evaluate predictive variables iteratively until a robust model was identified. The final model was tested on a second, independent group of 32 samples, including six samples from patients diagnosed with lung cancer.

RESULTS

Automated analysis combined with machine learning resulted in a predictive model that achieved an area under the ROC curve (AUC) of 0.89 (95% CI 0.83-0.89). The sensitivity and specificity were 82% and 88%, respectively, and the negative and positive predictive values 96% and 61%, respectively. Importantly, the test was 92% sensitive and 87% specific in cases when nodules were < 20 mm (AUC of 0.94; 95% CI 0.89-0.99). Testing of the model on an independent second set of samples showed an AUC of 0.85 (95% CI 0.71-0.98) with an 83% sensitivity, 77% specificity, 95% negative predictive value and 45% positive predictive value. The model is robust to differences in sample processing and disease state.

CONCLUSION

CyPath Lung correctly classifies samples as cancer or non-cancer with high accuracy, including from participants at different disease stages and with nodules < 20 mm in diameter. This test is intended for use after lung cancer screening to improve early-stage lung cancer diagnosis. Trial registration ClinicalTrials.gov ID: NCT03457415; March 7, 2018.

K63 Ubiquitination of P21 Can Facilitate Pellino-1 in the Context of Chronic Obstructive Pulmonary Disease and Lung Cellular Senescence

Chronic obstructive pulmonary diseases (COPD) is a kind of age-related, airflow-obstruction disease mostly caused by cigarette smoke. However, the relationship between COPD and lung cellular senescence is still not fully understood. Here, we found silencing Pellino-1 could inhibit the protein level of P21. Then, through constructing cell lines expressed ubiquitin-HA, we found that the E3 ubiquitin ligase Pellino-1 could bind to senescence marker p21 and modify p21 by K63-site ubiquitination by co-IP assays. Furthermore, we found that p21-mediated lung cellular senescence could be inhibited by silencing Pellino-1 in a D-galactose senescence mice model. Moreover, by constructing a COPD mouse model with shPellino-1 adenovirus, we found that silencing Pellino-1 could inhibit COPD and inflammation via reduction of SASPs regulated by p21. Taken together, our study findings elucidated that silencing E3 ligase Pellino-1 exhibits therapeutic potential for treatment to attenuate the progression of lung cellular senescence and COPD.

Tuberculosis in an Aging World

Tuberculosis (TB) is one of the leading causes of death due to its being an infectious disease, caused by the airborne pathogen Mycobacterium tuberculosis (M.tb). Approximately one-fourth of the world’s population is infected with latent M.tb, and TB is considered a global threat killing over 4000 people every day. The risk of TB susceptibility and mortality is significantly increased in individuals aged 65 and older, confirming that the elderly represent one of the largest reservoirs for M.tb infection. The elderly population faces many challenges that increase their risk of developing respiratory diseases, including TB. The challenges the elderly face in this regard include the following: decreased lung function, immuno-senescence, inflammaging, adverse drug effects, low tolerance to anti-TB drugs, lack of suitable diagnoses/interventions, and age-associated comorbidities. In order to find new therapeutic strategies to maintain lung homeostasis and resistance to respiratory infections as we age, it is necessary to understand the molecular and cellular mechanisms behind natural lung aging. This review focuses primarily on why the elderly are more susceptible to TB disease and death, with a focus on pulmonary function and comorbidities.

Pulmonary function is associated with cognitive decline and structural brain differences

The association of poor pulmonary function (PF) with cognitive trajectories and structural brain differences remains unclear. Within the Rush Memory and Aging Project, 1377 dementia-free subjects were followed up to 21 years. PF was assessed with a composite score measured at baseline. Global and domain-specific cognitive function was assessed annually constructed from 19 cognitive tests. A subsample of 351 participants underwent brain magnetic resonance imaging to investigate the cross-sectional association between PF and structural brain volumes. We found that low PF was related to faster decline in global cognition, and domain-specific function including episodic memory, semantic memory, working memory, visuospatial ability, and perceptual speed. In addition, low PF was associated with smaller volumes of total brain, white matter and gray matter, and larger white matter hyperintensities volume. Our results suggest that low PF is associated with faster cognitive decline, and both neurodegeneration and vascular brain lesions may underlie the association.

Immunosenescence, immune fitness and vaccination schedule in the adult respiratory patient

Immunosenescence is the gradual deterioration of the immune system caused by advancing age. It is associated with a reduced ability to respond to infections and develop long-term immune memory. It plays a key role in the development of respiratory diseases that are more common in older people, such as asthma, COPD, diffuse interstitial disease and respiratory infections in the elderly.

We call immune fitness the establishment of lifestyle habits that can improve our immune capacity. We now know that good eating habits, good social relationships, not smoking, limiting alcohol consumption, exercising, controlling stress levels and establishing a proper vaccination programme can slow down the process of immunosenescence.

Influenza and pneumococcal vaccines (PCV13 and PPSV23 conjugate) are well established in the adult vaccination schedule. The new pneumococcal vaccines PCV15 and PCV20 will help to extend protection against pneumococcal disease in adults. The vaccine against COVID-19 is currently the most useful tool to prevent the disease and reduce its pathogenicity. COPD patients and others with respiratory diseases may benefit from prevention of herpes zoster and Bordetella pertussis through vaccination. Respiratory syncytial virus (RSV) vaccine may be another vaccine to be added to the schedule, pending the results of its studies.

The profibrotic and senescence phenotype of old lung fibroblasts is reversed or ameliorated by genetic and pharmacological manipulation of Slc7a11 expression

Increased senescence and expression of profibrotic genes in old lung fibroblasts contribute to disrepair responses. We reported that primary lung fibroblasts from old mice have lower expression and activity of the cystine transporter Slc7a11/xCT than cells from young mice, resulting in changes in both the intracellular and extracellular redox environments. This study examines the hypothesis that low Slc7a11 expression in old lung fibroblasts promotes senescence and profibrotic gene expression. The levels of mRNA and protein of Slc7a11, senescence markers, and profibrotic genes were measured in primary fibroblasts from the lungs of old (24 mo) and young (3 mo) mice. In addition, the effects of genetic and pharmacological manipulation of Slc7a11 were investigated. We found that decreased expression of Slc7a11 in old cells was associated with elevated markers of senescence (p21, p16, p53, and β-galactosidase) and increased expression of profibrotic genes (Tgfb1, Smad3, Acta2, Fn1, Col1a1, and Col5a1). Silencing of Slc7a11 in young cells replicated the aging phenotype, whereas overexpression of Slc7a11 in old cells decreased expression of senescence and profibrotic genes. Young cells were induced to express the senescence and profibrotic phenotype by sulfasalazine, a Slc7a11 inhibitor, whereas treatment of old cells with sulforaphane, a Slc7a11 inducer, decreased senescence without affecting profibrotic genes. Like aging cells, idiopathic pulmonary fibrosis fibroblasts show decreased Slc7a11 expression and increased profibrotic markers. In short, old lung fibroblasts manifest a profibrotic and senescence phenotype that is modulated by genetic or pharmacological manipulation of Slc7a11.

Stiffness reduction and collagenase resistance of aging lungs measured using scanning acoustic microscopy

Lung tissue stiffness is altered with aging. Quantitatively evaluating lung function is difficult using a light microscope (LM) alone. Scanning acoustic microscope (SAM) calculates the speed-of-sound (SOS) using sections to obtain histological images by plotting SOS values on the screen. As SOS is positively correlated with stiffness, SAM has a superior characteristic of simultaneously evaluating tissue stiffness and structure. SOS images of healthy bronchioles, arterioles, and alveoli were compared among young, middle-aged, and old lung sections. Formalin-fixed, paraffin-embedded (FFPE) sections consistently exhibited relatively higher SOS values than fresh-frozen sections, indicating that FFPE became stiffer but retained the relative stiffness reflecting fresh samples. All lung components exhibited gradually declining SOS values with aging and were associated with structural alterations such as loss of smooth muscles, collagen, and elastic fibers. Moreover, reaction to collagenase digestion resulted in decreased SOS values. SOS values of all components were significantly reduced in young and middle-aged groups, whereas no significant reduction was observed in the old group. Protease damage in the absence of regeneration or loss of elastic components was present in old lungs, which exbited dilated bronchioles and alveoli. Aging lungs gradually lose stiffness with decreasing structural components without exposure to specific insults such as inflammation.

Sex, ancestry, senescence, and aging (SAnSA) are stark drivers of nontuberculous mycobacterial pulmonary disease

Nontuberculous mycobacterial (NTM) pulmonary disease (PD) disproportionately affects otherwise healthy, older, Caucasian females. The reasons behind this are likely multifactorial involving several conspiring factors. A variety of factors are thought to contribute to increased susceptibility to NTM in the older adult including exposure to various environmental conditions and contaminants across the lifespan, genetic risk factors, hormonal changes, and immunodeficiency. Independent of sex and ancestry, respiratory muscle atrophy intensifies with age and an aging immune system can show functional decline of macrophages, poor lung migration and homing of dendritic cells, promotion of aberrant pro-inflammatory responses, acceleration of inflammation related to aging, and increased immunosenescence. The purpose of this review is to synthesize the current body of knowledge regarding the roles of sex, ancestry, senescence, and aging (SAnSA) in NTM acquisition and the possible mechanisms involved in NTM PD, highlighting age-related respiratory and immune system changes. We also summarize molecular tools and biomarkers of these fields and contextualize these into the study of NTM PD. Finally, we discuss the relevance of biomarkers described for senescence and aging and senolytic therapies as potentially new adjunctive strategies to reduce the burden of NTM PD.

Increased LGR6 Expression Sustains Long-Term Wnt Activation and Acquisition of Senescence in Epithelial Progenitors in Chronic Lung Diseases

Chronic lung diseases (CLDs) represent a set of disorders characterized by the progressive loss of proper lung function. Among severe CLDs, the incidence of chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) has grown over the last decades, mainly in the elderly population. Several studies have highlighted an increased expression of senescence-related markers in the resident progenitor cells in COPD and IPF, possibly undermining epithelial integrity and contributing to the progression and the aggravation of both diseases. Recently, the chronic activation of the canonical Wnt/β-catenin pathway was shown to induce cellular senescence. Here, we investigated the localization and the expression of leucin-rich repeat-containing G-protein-coupled receptor 6 (LGR6), a protein that activates and potentiates the canonical Wnt signalling. Through immunohistochemical analyses, we identified a lesion-associated rise in LGR6 levels in abnormal lung epithelial progenitors in COPD and IPF when compared to histologically normal tissues. Moreover, in areas of aberrant regeneration, chronic damage and fibrosis, LGR6-expressing epithelial progenitors displayed a major increase in the expression of senescence-associated markers. Our study suggests the involvement of LGR6 in the chronic activation of the Wnt/β-catenin pathway, mediating the impairment and exhaustion of epithelial progenitors in COPD and IPF.

Tenascin-C: Friend or Foe in Lung Aging?

Lung aging is characterized by lung function impairment, ECM remodeling and airspace enlargement. Tenascin-C (TNC) is a large extracellular matrix (ECM) protein with paracrine and autocrine regulatory functions on cell migration, proliferation and differentiation. This matricellular protein is highly expressed during organogenesis and morphogenetic events like injury repair, inflammation or cancer. We previously showed that TNC deficiency affected lung development and pulmonary function, but little is known about its role during pulmonary aging. In order to answer this question, we characterized lung structure and physiology in 18 months old TNC-deficient and wild-type (WT) mice. Mice were mechanically ventilated with a basal and high tidal volume (HTV) ventilation protocol for functional analyses. Additional animals were used for histological, stereological and molecular biological analyses. We observed that old TNC-deficient mice exhibited larger lung volume, parenchymal volume, total airspace volume and septal surface area than WT, but similar mean linear intercept. This was accompanied by an increase in proliferation, but not apoptosis or autophagy markers expression throughout the lung parenchyma. Senescent cells were observed in epithelial cells of the conducting airways and in alveolar macrophages, but equally in both genotypes. Total collagen content was doubled in TNC KO lungs. However, basal and HTV ventilation revealed similar respiratory physiological parameters in both genotypes. Smooth muscle actin (α-SMA) analysis showed a faint increase in α-SMA positive cells in TNC-deficient lungs, but a marked increase in non-proliferative α-SMA + desmin + cells. Major TNC-related molecular pathways were not up- or down-regulated in TNC-deficient lungs as compared to WT; only minor changes in TLR4 and TGFβR3 mRNA expression were observed. In conclusion, TNC-deficient lungs at 18 months of age showed exaggerated features of the normal structural lung aging described to occur in mice between 12 and 18 months of age. Correlated to the increased pulmonary function parameters previously observed in young adult TNC-deficient lungs and described to occur in normal lung aging between 3 and 6 months of age, TNC might be an advantage in lung aging.

Can Exhaled Carbon Monoxide Be Used as a Marker of Exposure? A Cross-Sectional Study in Young Adults

Carbon monoxide (CO) poisoning is a major public health issue worldwide. People are exposed to CO in their daily lives, with one of the common sources of CO being cigarette smoking. Inhalation of CO leads to elevated carboxyhaemoglobin (COHb) levels in the blood and also in exhaled CO concentration. Several factors have been shown to affect COHb concentration and COHb half-life. However, factors affecting exhaled CO concentration and exhaled CO half-life are not well understood. The present study aimed to investigate the potential factors related to baseline exhaled CO concentration and exhaled CO half-life among smokers. A cross-sectional study was conducted between 26 January and 30 June 2019, and young adults were recruited into the study. A total of 74 participants (mean age: 27.1 years, 71.6% males and 28.4% females) attended the study. They were invited to complete a questionnaire, including demographic, physiological, and behavioural factors. Then, exhaled CO measurements were taken. These measurements were taken before and after smoking a single cigarette for smokers and only once for non-smokers. The average baseline exhaled CO concentration was 6.9 ± 4.9 ppm for smokers and 1.9 ± 0.5 ppm for non-smokers. The mean of exhaled CO half-life was around 273.3 min (4.6 h) for smokers. No difference was seen in exhaled CO half-life between light smokers and heavy smokers in the smoking group. Gender and cigarettes smoked weekly affected baseline exhaled CO in smokers. Even though height seemed to positively associate with exhaled CO half-life, the relationship disappeared when adjusting by gender and weight. Therefore, exhaled CO could be used as a marker of CO exposure, but we cannot ignore the factors mentioned in the study. For future study, considering factors related to smoking habits and smoking style are recommended as these may affect total inhaled CO.

Redox Dysregulation in Aging and COPD: Role of NOX Enzymes and Implications for Antioxidant Strategies

With a rapidly growing elderly human population, the incidence of age-related lung diseases such as chronic obstructive pulmonary disease (COPD) continues to rise. It is widely believed that reactive oxygen species (ROS) play an important role in ageing and in age-related disease, and approaches of antioxidant supplementation have been touted as useful strategies to mitigate age-related disease progression, although success of such strategies has been very limited to date. Involvement of ROS in ageing is largely attributed to mitochondrial dysfunction and impaired adaptive antioxidant responses. NADPH oxidase (NOX) enzymes represent an important enzyme family that generates ROS in a regulated fashion for purposes of oxidative host defense and redox-based signalling, however, the associations of NOX enzymes with lung ageing or age-related lung disease have to date only been minimally addressed. The present review will focus on our current understanding of the impact of ageing on NOX biology and its consequences for age-related lung disease, particularly COPD, and will also discuss the implications of altered NOX biology for current and future antioxidant-based strategies aimed at treating these diseases.

Dry Wearable Textile Electrodes for Portable Electrical Impedance Tomography

Electrical impedance tomography (EIT), a noninvasive and radiation-free medical imaging technique, has been used for continuous real-time regional lung aeration. However, adhesive electrodes could cause discomfort and increase the risk of skin injury during prolonged measurement. Additionally, the conductive gel between the electrodes and skin could evaporate in long-term usage and deteriorate the signal quality. To address these issues, in this work, textile electrodes integrated with a clothing belt are proposed to achieve EIT lung imaging along with a custom portable EIT system. The simulation and experimental results have verified the validity of the proposed portable EIT system. Furthermore, the imaging results of using the proposed textile electrodes were compared with commercial electrocardiogram electrodes to evaluate their performance.

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.

Type I Interferon signaling controls the accumulation and transcriptomes of monocytes in the aged lung

Aging is paradoxically associated with a deteriorated immune defense (immunosenescence) and increased basal levels of tissue inflammation (inflammaging). The lung is particularly sensitive to the effects of aging. The immune cell mechanisms underlying physiological lung aging remain poorly understood. Here we reveal that aging leads to increased interferon signaling and elevated concentrations of chemokines in the lung, which is associated with infiltration of monocytes into the lung parenchyma. scRNA‐seq identified a novel Type‐1 interferon signaling dependent monocyte subset (MO‐ifn) that upregulated IFNAR1 expression and exhibited greater transcriptomal changes with aging than the other monocytes. Blockade of type‐1 interferon signaling by treatment with anti‐IFNAR1 neutralizing antibodies rapidly ablated MO‐ifn cells. Treatment with anti‐IFNAR1 antibodies also reduced airway chemokine concentrations and repressed the accumulation of the overall monocyte population in the parenchyma of the aged lung. Together, our work suggests that physiological aging is associated with increased basal level of airway monocyte infiltration and inflammation in part due to elevated type‐1 interferon signaling.

Ageing mechanisms that contribute to tissue remodeling in lung disease

Age is a major risk factor for chronic respiratory diseases such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and certain phenotypes of asthma. The recent COVID-19 pandemic also highlights the increased susceptibility of the elderly to acute respiratory distress syndrome (ARDS), a diffuse inflammatory lung injury with often long-term effects (ie parenchymal fibrosis). Collectively, these lung conditions are characterized by a pathogenic reparative process that, rather than restoring organ function, contributes to structural and functional tissue decline. In the ageing lung, the homeostatic control of wound healing following challenge or injury has an increased likelihood of being perturbed, increasing susceptibility to disease. This loss of fidelity is a consequence of a diverse range of underlying ageing mechanisms including senescence, mitochondrial dysfunction, proteostatic stress and diminished autophagy that occur within the lung, as well as in other tissues, organs and systems of the body. These ageing pathways are highly interconnected, involving localized and systemic increases in inflammatory mediators and damage associated molecular patterns (DAMPs); along with corresponding changes in immune cell function, metabolism and composition of the pulmonary and gut microbiomes. Here we comprehensively review the roles of ageing mechanisms in the tissue remodeling of lung disease.

Association of lung function with functional limitation in older adults: A cross-sectional study

INTRODUCTION

Impaired lung function is independently associated with higher rates of disability, however, few studies have examined the association between lung function and functional limitation. This study aimed to assess this association and dose-response relationship in older adults.

METHODS

Data from the National Health and Nutrition Examination Survey (2007-2012) was used as a cross-sectional study. Lung function was determined by Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Functional limitation in older adults was identified by six self-reported questions on physical function. 3070 adults aged 60 and over were enrolled in our study. Logistic regression models and restricted cubic spline models were applied to examine the association between lung function and the risk of functional limitation.

RESULTS

FEV1 and FVC were inversely associated with the risk of functional limitation. In the full adjusted model, compared with the lowest tertile of FEV1, the odds ratios (95% confidence intervals) of functional limitation for tertile 2 and tertile 3 were 0.5422 (0.3848-0.7639) and 0.4403 (0.2685-0.7220), and the odds ratios (95% confidence intervals) of functional limitation for tertile 2 and tertile 3 of FVC were 0.5243 (0.3503-0.7848) and 0.3726 (0.2072-0.6698). Furthermore, an inverse association persisted after stratified analysis by gender and sensitivity analysis. Dose-response analyses showed that the odds of functional limitation declined with increase in FEV1 and FVC in a nonlinear manner.

CONCLUSIONS

Lung function was inversely associated with functional limitation among older adults.

Downregulation of DUOX1 function contributes to aging-related impairment of innate airway injury responses and accelerated senile emphysema

Aging is associated with a gradual loss of lung function due to increased cellular senescence, decreased regenerative capacity, and impaired innate host defense. One important aspect of innate airway epithelial host defense to nonmicrobial triggers is the secretion of alarmins such as IL-33 and activation of type 2 inflammation, which were previously found to depend on activation of the NADPH oxidase (NOX) homolog DUOX1, and redox-dependent signaling pathways that promote alarmin secretion. Here, we demonstrate that normal aging of C57BL/6J mice resulted in markedly decreased lung innate epithelial type 2 responses to exogenous triggers such as the airborne allergen Dermatophagoides pteronyssinus, which was associated with marked downregulation of DUOX1, as well as DUOX1-mediated redox-dependent signaling. DUOX1 deficiency was also found to accelerate age-related airspace enlargement and decline in lung function but did not consistently affect other features of lung aging such as senescence-associated inflammation. Intriguingly, observations of age-related DUOX1 downregulation and enhanced airspace enlargement due to DUOX1 deficiency in C57BL/6J mice, which lack a functional mitochondrial nicotinamide nucleotide transhydrogenase (NNT), were much less dramatic in C57BL/6NJ mice with normal NNT function, although the latter mice also displayed impaired innate epithelial injury responses with advancing age. Overall, our findings indicate a marked aging-dependent decline in (DUOX1-dependent) innate airway injury responses to external nonmicrobial triggers, but the impact of aging on DUOX1 downregulation and its significance for age-related senile emphysema development was variable between different C57BL6 substrains, possibly related to metabolic alterations due to differences in NNT function.

The Stress of Lung Aging: Endoplasmic Reticulum and Senescence Tête-à-Tête

Beyond the structural changes, features including the dysregulation of endoplasmic reticulum (ER) stress response and increased senescence characterize the lung aging. ER stress response and senescence have been reported to be induced by factors like cigarette smoke. Therefore, deciphering the mechanisms underlying ER and senescent pathways interaction has become a challenge. In this review we highlight the known and unknown regarding ER stress response and senescence and their cross talk in aged lung.

Ventilatory defects and treatable traits in very elderly patients

Though the approach used to classify chronic respiratory diseases is changing to a treatable-traits (TT) approach, data regarding very elderly patients is lacking. The objectives of this study were to assess TT frequency in very elderly patients and to study the link between extrapulmonary TT and ventilatory defects. Individuals (≥75 years) residing in elderly care centres answered a standardised questionnaire, underwent spirometry, atopy and fractional exhaled nitric oxide assessments and had their blood pressure and peripheral pulse oximetry measured. Pulmonary, extrapulmonary and behavioural TT were evaluated. Outcome variables were an airflow limitation (post-bronchodilator z-score FEV1/FVC<-1.64) and a restrictive spirometry pattern (z-score FEV1/FVC ≥ +1.64 and z-score FVC<-1.64). Seventy-two percent of the individuals who took part in the study (n = 234) were women, and the median age of participants was 86 (IQR: 7.4). At least one pulmonary TT was identified in 105 (44.9%) individuals. The most frequent extrapulmonary TTs were: persistent systemic inflammation (47.0%), anaemia (34.4%), depression (32.5%) and obesity (27.4). Airflow limitation was exclusively associated with smoking (OR 5.03; 95% CI 1.56-16.22). A restrictive spirometry pattern was associated with cognitive impairment (OR: 3.89; 95% CI: 1.55-9.79). A high frequency of various TTs was found. The novel association between a restrictive spirometry pattern and cognitive impairment highlights the urgency of clinical research on this vulnerable age group.

Dysbiosis, malnutrition and enhanced gut-lung axis contribute to age-related respiratory diseases

Older people are at an increased risk of developing respiratory diseases such as chronic obstructive pulmonary diseases, asthma, idiopathic pulmonary fibrosis or lung infections. Susceptibility to these diseases is partly due to the intrinsic ageing process, characterized by genomic, cellular and metabolic hallmarks and immunosenescence, and is associated with changes in the intestinal microbiota. Importantly, in the lungs, ageing is also associated with a dysbiosis and loss of resilience of the resident microbiota and alterations of the gut-lung axis. Notably, as malnutrition is often observed in the elderly, nutrition is one of the most accessible modifiable factors affecting both senescence and microbiota. This article reviews the changes affecting the lung and its resident microbiota during ageing, as well as the interconnections between malnutrition, senescence, microbiota, gut-lung axis and respiratory health. As the communication along the gut-lung axis becomes more permissive with ageing, this review also explores the evidence that the gut and lung microbiota are key players in the maintenance of healthy lungs, and as such, are potential targets for nutrition-based preventive strategies against lung disease in elderly populations.

Undergraduate nursing students' experience of learning respiratory system assessment using flipped classroom: A mixed methods study

BACKGROUND

Knowledge and skill acquisition to perform an accurate respiratory system assessment is a key competency expected in undergraduate nursing students. Learning physical assessment requires the integration of multiple knowledge bases and skills; hence, applying an innovative teaching approach, such as the flipped-classroom (FC) approach, fosters an active and student-centered learning environment for physical assessment class.

OBJECTIVES

This study evaluated FC's feasibility in delivering respiratory system assessment content in a health assessment course and explored the changes in nursing students' perceptions regarding student-centeredness and active learning environments before and after applying FC.

DESIGN

A single group pre- and post-test concurrent mixed-methods design was used.

SETTINGS

This study was conducted in a private nursing college in South Korea.

PARTICIPANTS

A convenience sample of 91 second year undergraduate nursing students enrolled in a health assessment course.

METHODS

FC was offered at one didactic session of a physical assessment course. In the FC, students completed a self-directed pre-class activities using online lecture videos and reading materials prior to the class and participated in interactive team-based learning activities inside the classroom. Skills lab practicum took place after the FC. Students' perceptions regarding student-centeredness and active learning environments, in terms of teaching, social, and cognitive presences were measured before (T1) and after (T2) conducting the FC. Qualitative data were obtained at T2 using free-response questions, which required students to comment on their FC experience.

RESULTS

Participants' perceptions of student-centeredness significantly increased from T1 to T2. Although student-perceived teaching and social presence in their learning environment showed upward trends from T1 to T2, these changes were not statistically significant. Students considered FC an acceptable approach to foster active learning in a supportive learning environment.

CONCLUSIONS

This study revealed that incorporating FC to deliver respiratory system assessment content was feasible and considered acceptable by undergraduate nursing students.

Senescence in Pulmonary Fibrosis: Between Aging and Exposure

To date, chronic pulmonary pathologies represent the third leading cause of death in the elderly population. Evidence-based projections suggest that >65 (years old) individuals will account for approximately a quarter of the world population before the turn of the century. Genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication, are described as the nine “hallmarks” that govern cellular fitness. Any deviation from the normal pattern initiates a complex cascade of events culminating to a disease state. This blueprint, originally employed to describe aberrant changes in cancer cells, can be also used to describe aging and fibrosis. Pulmonary fibrosis (PF) is the result of a progressive decline in injury resolution processes stemming from endogenous (physiological decline or somatic mutations) or exogenous stress. Environmental, dietary or occupational exposure accelerates the pathogenesis of a senescent phenotype based on (1) window of exposure; (2) dose, duration, recurrence; and (3) cells type being targeted. As the lung ages, the threshold to generate an irreversibly senescent phenotype is lowered. However, we do not have sufficient knowledge to make accurate predictions. In this review, we provide an assessment of the literature that interrogates lung epithelial, mesenchymal, and immune senescence at the intersection of aging, environmental exposure and pulmonary fibrosis.

Small airway loss in the physiologically ageing lung: a cross-sectional study in unused donor lungs

BACKGROUND

Physiological lung ageing is associated with a gradual decline in dynamic lung volumes and a progressive increase in residual volume due to diminished elastic recoil of the lung, loss of alveolar tissue, and lower chest wall compliance. However, the effects of ageing on the small airways (ie, airways <2·0 mm in diameter) remain largely unknown. By using a combination of ex-vivo conventional CT (resolution 1 mm), whole lung micro-CT (resolution 150 μm), and micro-CT of extracted cores (resolution 10 μm), we aimed to provide a multiresolution assessment of the small airways in lung ageing in a large cohort of never smokers.

METHODS

For this cross-sectional study, we included donor lungs collected from 32 deceased never-smoking donors (age range 16-83 years). Ex-vivo CT and whole lung high-resolution CT (micro-CT) were used to determine total airway numbers, stratified by airway diameter. Micro-CT was used to assess the number, length, and diameter of terminal bronchioles (ie, the last generation of conducting airways); mean linear intercept; and surface density in four lung tissue cores from each lung, extracted using a uniform sampling approach. Regression β coefficients are calculated using linear regression and polynomial models.

FINDINGS

Ex-vivo CT analysis showed an age-dependent decrease in the number of airways of diameter 2·0 mm to less than 2·5 mm (β coefficient per decade -0·119, 95% CI -0·193 to -0·045; R²=0·29) and especially in airways smaller than 2·0 mm in diameter (-0·158, -0·233 to -0·084; R²=0·47), between 30 and 80 years of age, but not of the larger (≥2·5 mm) diameter airways (-0·00781, -0·04409 to 0·02848; R²=0·0007). In micro-CT analysis of small airways, the total number of terminal bronchioles per lung increased until the age of 30 years, after which an almost linear decline in the number of terminal bronchioles was observed (β coefficient per decade -2035, 95% CI -2818 to -1252; R²=0·55), accompanied by a non-significant increase in alveolar airspace size (6·44, -0·57 to 13·45, R²=0·10). Moreover, this decrease in terminal bronchioles was associated with the age-related decline of pulmonary function predicted by healthy reference values.

INTERPRETATION

Loss of terminal bronchioles is an important structural component of age-related decline in pulmonary function of healthy, non-smoking individuals.

FUNDING

Research Foundation-Flanders, KU Leuven, Parker B Francis Foundation, UGent, Canadian Institutes for Health.

The untwining of immunosenescence and aging

From a holistic point of view, aging results from the cumulative erosion of the various systems. Among these, the immune system is interconnected to the rest as immune cells are present in all organs and recirculate through bloodstream. Immunosenescence is the term used to define the remodelling of immune changes during aging. Because immune cells-and particularly lymphocytes-can further differentiate after their maturation in response to pathogen recognition, it is therefore unclear when senescence is induced in these cells. Additionally, it is also unclear which signals triggers senescence in immune cells (i) aging per se, (ii) specific response to pathogens, (iii) underlying conditions, or (iv) inflammaging. In this review, we will cover the current knowledge and concepts linked to immunosenescence and we focus this review on lymphocytes and T cells, which represent the typical model for replicative senescence. With the evidence presented, we propose to disentangle the senescence of immune cells from chronological aging.

Clinical risk score to predict in-hospital mortality in COVID-19 patients: a retrospective cohort study

OBJECTIVES

Several physiological abnormalities that develop during COVID-19 are associated with increased mortality. In the present study, we aimed to develop a clinical risk score to predict the in-hospital mortality in COVID-19 patients, based on a set of variables available soon after the hospitalisation triage.

SETTING

Retrospective cohort study of 516 patients consecutively admitted for COVID-19 to two Italian tertiary hospitals located in Northern and Central Italy were collected from 22 February 2020 (date of first admission) to 10 April 2020.

PARTICIPANTS

Consecutive patients≥18 years admitted for COVID-19.

MAIN OUTCOME MEASURES

Simple clinical and laboratory findings readily available after triage were compared by patients' survival status ('dead' vs 'alive'), with the objective of identifying baseline variables associated with mortality. These were used to build a COVID-19 in-hospital mortality risk score (COVID-19MRS).

RESULTS

Mean age was 67±13 years (mean±SD), and 66.9% were male. Using Cox regression analysis, tertiles of increasing age (≥75, upper vs <62 years, lower: HR 7.92; p<0.001) and number of chronic diseases (≥4 vs 0-1: HR 2.09; p=0.007), respiratory rate (HR 1.04 per unit increase; p=0.001), PaO2/FiO2 (HR 0.995 per unit increase; p<0.001), serum creatinine (HR 1.34 per unit increase; p<0.001) and platelet count (HR 0.995 per unit increase; p=0.001) were predictors of mortality. All six predictors were used to build the COVID-19MRS (Area Under the Curve 0.90, 95% CI 0.87 to 0.93), which proved to be highly accurate in stratifying patients at low, intermediate and high risk of in-hospital death (p<0.001).

CONCLUSIONS

The COVID-19MRS is a rapid, operator-independent and inexpensive clinical tool that objectively predicts mortality in patients with COVID-19. The score could be helpful from triage to guide earlier assignment of COVID-19 patients to the most appropriate level of care.

Wnt signaling pathway in aging-related tissue fibrosis and therapies

Fibrosis is the final hallmark of pathological remodeling, which is a major contributor to the pathogenesis of various chronic diseases and aging-related organ failure to fully control chronic wound-healing and restoring tissue function. The process of fibrosis is involved in the pathogenesis of the kidney, lung, liver, heart and other tissue disorders. Wnt is a highly conserved signaling in the aberrant wound repair and fibrogenesis, and sustained Wnt activation is correlated with the pathogenesis of fibrosis. In particular, mounting evidence has revealed that Wnt signaling played important roles in cell fate determination, proliferation and cell polarity establishment. The expression and distribution of Wnt signaling in different tissues vary with age, and these changes have key effects on maintaining tissue homeostasis. In this review, we first describe the major constituents of the Wnt signaling and their regulation functions. Subsequently, we summarize the dysregulation of Wnt signaling in aging-related fibrotic tissues such as kidney, liver, lung and cardiac fibrosis, followed by a detailed discussion of its involvement in organ fibrosis. In addition, the crosstalk between Wnt signaling and other pathways has the potential to profoundly add to the complexity of organ fibrosis. Increasing studies have demonstrated that a number of Wnt inhibitors had the potential role against tissue fibrosis, specifically in kidney fibrosis and the implications of Wnt signaling in aging-related diseases. Therefore, targeting Wnt signaling might be a novel and promising therapeutic strategy against aging-related tissue fibrosis.

Cellular Senescence as a Mechanism and Target in Chronic Lung Diseases

Cellular senescence is now considered an important driving mechanism for chronic lung diseases, particularly chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. Cellular senescence is due to replicative and stress-related senescence with activation of p53 and p16^INK4a, respectively, leading to activation of p21^CIP1 and cell cycle arrest. Senescent cells secrete multiple inflammatory proteins known as the senescence-associated secretory phenotype, leading to low-grade chronic inflammation, which further drives senescence. Loss of key antiaging molecules sirtuin-1 and sirtuin-6 may be important in acceleration of aging and arises from oxidative stress reducing phosphatase PTEN (phosphatase tensin homolog), thereby activating PI3K (phosphoinositide-3-kinase) and mTOR (mammalian target of rapamycin). MicroRNA-34a (miR-34a), which is regulated by PI3K-mTOR signaling, plays a pivotal role in reducing sirtuin-1/6, and its inhibition with an antagomir results in their restoration, reducing markers of senescence, reducing senescence-associated secretory phenotype, and reversing cell cycle arrest in epithelial cells from peripheral airways of patients with COPD. miR-570 is also involved in reduction of sirtuin-1 and cellular senescence and is activated by p38 mitogen-activated protein kinase. These miRNAs may be released from cells in extracellular vesicles that are taken up by other cells, thereby spreading senescence locally within the lung but also outside the lung through the circulation; this may account for comorbidities of COPD and other lung diseases. Understanding the mechanisms of cellular senescence may result in new treatments for chronic lung disease, either by inhibiting PI3K-mTOR signaling, by inhibiting specific miRNAs, or by deletion of senescent cells with senolytic therapies, already shown to be effective in experimental lung fibrosis.

Chronic WNT/β-catenin signaling induces cellular senescence in lung epithelial cells

The rapid expansion of the elderly population has led to the recent epidemic of age-related diseases, including increased incidence and mortality of chronic lung diseases, such as Idiopathic Pulmonary Fibrosis (IPF). Cellular senescence is a major hallmark of aging and has a higher occurrence in IPF. The lung epithelium represents a major site of tissue injury, cellular senescence and aberrant activity of developmental pathways such as the WNT/β-catenin pathway in IPF. The potential impact of WNT/β-catenin signaling on alveolar epithelial senescence in general as well as in IPF, however, remains elusive. Here, we characterized alveolar epithelial cells of aged mice and assessed the contribution of chronic WNT/β-catenin signaling on alveolar epithelial type (AT) II cell senescence. Whole lungs from old (16-24 months) versus young (3 months) mice had relatively less epithelial (EpCAM⁺) but more inflammatory (CD45⁺) cells, as assessed by flow cytometry. Compared to young ATII cells, old ATII cells showed decreased expression of the ATII cell marker Surfactant Protein C along with increased expression of the ATI cell marker Hopx, accompanied by increased WNT/β-catenin activity. Notably, when placed in an organoid assay, old ATII cells exhibited decreased progenitor cell potential. Chronic canonical WNT/β-catenin activation for up to 7 days in primary ATII cells as well as alveolar epithelial cell lines induced a robust cellular senescence, whereas the non-canonical ligand WNT5A was not able to induce cellular senescence. Moreover, chronic WNT3A treatment of precision-cut lung slices (PCLS) further confirmed ATII cell senescence. Simultaneously, chronic but not acute WNT/β-catenin activation induced a profibrotic state with increased expression of the impaired ATII cell marker Keratin 8. These results suggest that chronic WNT/β-catenin activity in the IPF lung contributes to increased ATII cell senescence and reprogramming. In the fibrotic environment, WNT/β-catenin signaling thus might lead to further progenitor cell dysfunction and impaired lung repair.

Viral Infection Increases the Risk of Idiopathic Pulmonary Fibrosis: A Meta-Analysis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease with a poor prognosis. Although many factors have been identified that possibly trigger or aggravate IPF, such as viral infection, the exact cause of IPF remains unclear. Until now, there has been no systematic review to assess the role of viral infection in IPF quantitatively.

OBJECTIVE

This meta-analysis aims to present a collective view on the relationship between viral infection and IPF.

METHODS

We searched studies reporting the effect of viral infection on IPF in the PubMed, Embase, Cochrane Library, Web of Science, and Wiley Online Library databases. We calculated ORs with 95% CIs to assess the risk of virus in IPF. We also estimated statistical heterogeneity by using I² and Cochran Q tests and publication bias by using the funnel plot, Begg test, Egger test, and trim-and-fill methods. Regression, sensitivity, and subgroup analyses were performed to assess the effects of confounding factors, such as sex and age.

RESULTS

We analyzed 20 case-control studies from 10 countries with 1,287 participants. The pooled OR of all viruses indicated that viral infection could increase the risk of IPF significantly (OR, 3.48; 95% CI, 1.61-7.52; P = .001), but not that of exacerbation of IPF (OR, 0.99; 95% CI, 0.47-2.12; P = .988). All analyzed viruses, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8), were associated with a significant elevation in the risk of IPF, except human herpesvirus 6 (HHV-6).

CONCLUSIONS

The presence of persistent or chronic, but not acute, viral infections, including EBV, CMV, HHV-7, and HHV-8, significantly increases the risk of developing IPF, but not exacerbation of IPF. These findings imply that viral infection could be a potential risk factor for IPF.