Mechanisms of lung aging

Fibroblast senescence-associated extracellular matrix promotes heterogeneous lung niche

Senescent cell accumulation in the pulmonary niche is associated with heightened susceptibility to age-related disease, tissue alterations, and ultimately a decline in lung function. Our current knowledge of senescent cell-extracellular matrix (ECM) dynamics is limited, and our understanding of how senescent cells influence spatial ECM architecture changes over time is incomplete. Herein is the design of an in vitro model of senescence-associated extracellular matrix (SA-ECM) remodeling using a senescent lung fibroblast-derived matrix that captures the spatiotemporal dynamics of an evolving senescent ECM architecture. Multiphoton second-harmonic generation microscopy was utilized to examine the spatial and temporal dynamics of fibroblast SA-ECM remodeling, which revealed a biphasic process that established a disordered and heterogeneous architecture. Additionally, we observed that inhibition of transforming growth factor-β signaling during SA-ECM remodeling led to improved local collagen fiber organization. Finally, we examined patient samples diagnosed with pulmonary fibrosis to further tie our results of the in vitro model to clinical outcomes. Moreover, we observed that the senescence marker p16 is correlated with local collagen fiber disorder. By elucidating the temporal dynamics of SA-ECM remodeling, we provide further insight on the role of senescent cells and their contributions to pathological ECM remodeling.

A Novel Air Trapping Segment Score Identifies Opposing Effects of Obesity and Eosinophilia on Air Trapping in Asthma

Rationale: Density thresholds in computed tomography (CT) lung scans quantify air trapping (AT) at the whole-lung level but are not informative for AT in specific bronchopulmonary segments. Objectives: To apply a segment-based measure of AT in asthma to investigate the clinical determinants of AT in asthma. Methods: In each of 19 bronchopulmonary segments in CT lung scans from 199 patients with asthma, AT was categorized as present if lung attenuation was less than -856 Hounsfield units at expiration in ⩾15% of the lung area. The resulting AT segment score (0-19) was related to patient outcomes. Measurements and Main Results: AT varied at the lung segment level and tended to persist at the patient and lung segment levels over 3 years. Patients with widespread AT (⩾10 segments) had more severe asthma (P < 0.05). The mean (±SD) AT segment score in patients with a body mass index ⩾30 kg/m2 was lower than in patients with a body mass index <30 kg/m2 (3.5 ± 4.6 vs. 5.5 ± 6.3; P = 0.008), and the frequency of AT in lower lobe segments in obese patients was less than in upper and middle lobe segments (35% vs. 46%; P = 0.001). The AT segment score in patients with sputum eosinophils ⩾2% was higher than in patients without sputum eosinophilia (7.0 ± 6.1 vs. 3.3 ± 4.9; P < 0.0001). Lung segments with AT more frequently had airway mucus plugging than lung segments without AT (48% vs. 18%; P ⩽ 0.0001). Conclusions: In patients with asthma, air trapping is more severe in those with airway eosinophilia and mucus plugging, whereas those who are obese have less severe trapping because their lower lobe segments are spared.

The alveolus: Our current knowledge of how the gas exchange unit of the lung is constructed and repaired

The mammalian lung completes its last step of development, alveologenesis, to generate sufficient surface area for gas exchange. In this process, multiple cell types that include alveolar epithelial cells, endothelial cells, and fibroblasts undergo coordinated cell proliferation, cell migration and/or contraction, cell shape changes, and cell-cell and cell-matrix interactions to produce the gas exchange unit: the alveolus. Full functioning of alveoli also involves immune cells and the lymphatic and autonomic nervous system. With the advent of lineage tracing, conditional gene inactivation, transcriptome analysis, live imaging, and lung organoids, our molecular understanding of alveologenesis has advanced significantly. In this review, we summarize the current knowledge of the constituents of the alveolus and the molecular pathways that control alveolar formation. We also discuss how insight into alveolar formation may inform us of alveolar repair/regeneration mechanisms following lung injury and the pathogenic processes that lead to loss of alveoli or tissue fibrosis.

Advanced lung organoids for respiratory system and pulmonary disease modeling

Amidst the recent coronavirus disease 2019 (COVID-19) pandemic, respiratory system research has made remarkable progress, particularly focusing on infectious diseases. Lung organoid, a miniaturized structure recapitulating lung tissue, has gained global attention because of its advantages over other conventional models such as two-dimensional (2D) cell models and animal models. Nevertheless, lung organoids still face limitations concerning heterogeneity, complexity, and maturity compared to the native lung tissue. To address these limitations, researchers have employed co-culture methods with various cell types including endothelial cells, mesenchymal cells, and immune cells, and incorporated bioengineering platforms such as air-liquid interfaces, microfluidic chips, and functional hydrogels. These advancements have facilitated applications of lung organoids to studies of pulmonary diseases, providing insights into disease mechanisms and potential treatments. This review introduces recent progress in the production methods of lung organoids, strategies for improving maturity, functionality, and complexity of organoids, and their application in disease modeling, including respiratory infection and pulmonary fibrosis.

Impact of lipopolysaccharide-induced acute lung injury in aged mice

Study Aim: As the geriatric population rapidly expands, there has been a concurrent increase in elderly admissions to intensive care units (ICUs). Acute lung injury (ALI) is a prevalent reason for these admissions and carries poorer survival rates for the aged population compared to younger counterparts. The aging lung is subject to physiological, cellular, and immunological changes. However, our understanding of how aging impacts the clinical progression of ALI is limited. This study explored the effect of aging using a murine model of ALI. Methods: Female C57BL/6J mice, aged 7-8 wk (young) and 18 months (aged), were divided into four groups: young controls, aged controls, young with ALI (YL), and aged with ALI (AL). ALI was induced via intratracheal administration of lipopolysaccharide (LPS, 0.5 mg/kg). The animals were euthanized 72 h after LPS exposure. Results: The AL group exhibited a significantly increased wet/dry ratio compared to the other three groups, including the YL group. The bronchoalveolar lavage (BAL) fluid in the AL group had more cells overall, including more neutrophils, than the other groups. Inflammatory cytokines in BAL fluid showed similar trends. Histological analyses demonstrated more severe lung injury and fibrosis in the AL group than in the other groups. Increased transcription of senescence-associated secretory phenotype markers, including PAI-1 and MUC5B, was more prominent in the AL group than in the other groups. This trend was also observed in BAL samples from humans with pneumonia. Conclusions: Aging may amplify lung damage and inflammatory responses in ALI. This suggests that physicians should exercise increased caution in the clinical management of aged patients with ALI.

A genomic perspective of the aging human and mouse lung with a focus on immune response and cellular senescence

BACKGROUND

The aging lung is a complex process and influenced by various stressors, especially airborne pathogens and xenobiotics. Additionally, a lifetime exposure to antigens results in structural and functional changes of the lung; yet an understanding of the cell type specific responses remains elusive. To gain insight into age-related changes in lung function and inflammaging, we evaluated 89 mouse and 414 individual human lung genomic data sets with a focus on genes mechanistically linked to extracellular matrix (ECM), cellular senescence, immune response and pulmonary surfactant, and we interrogated single cell RNAseq data to fingerprint cell type specific changes.

RESULTS

We identified 117 and 68 mouse and human genes linked to ECM remodeling which accounted for 46% and 27%, respectively of all ECM coding genes. Furthermore, we identified 73 and 31 mouse and human genes linked to cellular senescence, and the majority code for the senescence associated secretory phenotype. These cytokines, chemokines and growth factors are primarily secreted by macrophages and fibroblasts. Single-cell RNAseq data confirmed age-related induced expression of marker genes of macrophages, neutrophil, eosinophil, dendritic, NK-, CD4+, CD8+-T and B cells in the lung of aged mice. This included the highly significant regulation of 20 genes coding for the CD3-T-cell receptor complex. Conversely, for the human lung we primarily observed macrophage and CD4+ and CD8+ marker genes as changed with age. Additionally, we noted an age-related induced expression of marker genes for mouse basal, ciliated, club and goblet cells, while for the human lung, fibroblasts and myofibroblasts marker genes increased with age. Therefore, we infer a change in cellular activity of these cell types with age. Furthermore, we identified predominantly repressed expression of surfactant coding genes, especially the surfactant transporter Abca3, thus highlighting remodeling of surfactant lipids with implications for the production of inflammatory lipids and immune response.

CONCLUSION

We report the genomic landscape of the aging lung and provide a rationale for its growing stiffness and age-related inflammation. By comparing the mouse and human pulmonary genome, we identified important differences between the two species and highlight the complex interplay of inflammaging, senescence and the link to ECM remodeling in healthy but aged individuals.

Eotaxin-1/CCL11 promotes cellular senescence in human-derived fibroblasts through pro-oxidant and pro-inflammatory pathways

Introduction

Eotaxin-1/CCL11 is a pivotal chemokine crucial for eosinophil homing to the lungs of asthmatic patients. Recent studies also suggest that CCL11 is involved in the aging process, as it is upregulated in elderly, and correlated with shorter telomere length in leukocytes from asthmatic children. Despite its potential pro-aging effects, the precise contribution of CCL11 and the underlying mechanisms involved in the promotion of cellular senescence remains unclear. Therefore, the primary goal of this study was to explore the role of CCL11 on senescence development and the signaling pathways activated by this chemokine in lung fibroblasts.

Methods

To investigate the targets potentially modulated by CCL11, we performed an in silico analysis using PseudoCell. We validated in vitro the activation of these targets in the human lung fibroblast cell line MRC-5 following rhCCL11 exposure. Finally, we performed differential gene expression analysis in human airway epithelial cells of asthmatic patients to assess CCL11 signaling and activation of additional senescent markers.

Results

Our study revealed that eotaxin-1/CCL11 promote reactive oxygen secretion (ROS) production in lung fibroblasts, accompanied by increased activation of the DNA damage response (DDR) and p-TP53 and γH2AX. These modifications were accompanied by cellular senescence promotion and increased secretion of senescence-associated secretory phenotype inflammatory cytokines IL-6 and IL-8. Furthermore, our data show that airway epithelial lung cells from atopic asthmatic patients overexpress CCL11 along with aging markers such as CDKN2A (p16INK4a) and SERPINE1.

Discussion

These findings provide new insights into the mechanisms underlying the pro-aging effects of CCL11 in the lungs of asthmatic patients. Understanding the role of CCL11 on senescence development may have important implications for the treatment of age-related lung diseases, such as asthma.

Age-associated differences in the human lung extracellular matrix

Extracellular matrix (ECM) remodeling has been associated with chronic lung diseases. However, information about specific age-associated differences in lung ECM is currently limited. In this study, we aimed to identify and localize age-associated ECM differences in human lungs using comprehensive transcriptomic, proteomic, and immunohistochemical analyses. Our previously identified age-associated gene expression signature of the lung was re-analyzed limiting it to an aging signature based on 270 control patients (37-80 years) and focused on the Matrisome core geneset using geneset enrichment analysis. To validate the age-associated transcriptomic differences on protein level, we compared the age-associated ECM genes (false discovery rate, FDR < 0.05) with a profile of age-associated proteins identified from a lung tissue proteomics dataset from nine control patients (49-76 years) (FDR < 0.05). Extensive immunohistochemical analysis was used to localize and semi-quantify the age-associated ECM differences in lung tissues from 62 control patients (18-82 years). Comparative analysis of transcriptomic and proteomic data identified seven ECM proteins with higher expression with age at both gene and protein levels: COL1A1, COL6A1, COL6A2, COL14A1, FBLN2, LTBP4, and LUM. With immunohistochemistry, we demonstrated higher protein levels with age for COL6A2 in whole tissue, parenchyma, airway wall, and blood vessel, for COL14A1 and LUM in bronchial epithelium, and COL1A1 in lung parenchyma. Our study revealed that higher age is associated with lung ECM remodeling, with specific differences occurring in defined regions within the lung. These differences may affect lung structure and physiology with aging and as such may increase susceptibility to developing chronic lung diseases.NEW & NOTEWORTHY We identified seven age-associated extracellular matrix (ECM) proteins, i.e., COL1A1, COL6A1, COL6A2 COL14A1, FBLN2, LTBP4, and LUM with higher transcript and protein levels in human lung tissue with age. Extensive immunohistochemical analysis revealed significant age-associated differences for COL6A2 in whole tissue, parenchyma, airway wall, and vessel, for COL14A1 and LUM in bronchial epithelium, and COL1A1 in parenchyma. Our findings lay a new foundation for the investigation of ECM differences in age-associated chronic lung diseases.

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.

Peripheral interstitial lung abnormalities on LDCT in an asymptomatic, nonsmoking Chinese urban cohort

To retrospectively investigate the imaging features and the related influencing factors of peripheral interstitial lung abnormalities (PILA) that caused "normal aging" by low-dose computed tomography (LDCT) in an nonsmoking, asymptomatic Chinese urban cohort. The clinical data of 733 subjects who underwent chest LDCT were retrospectively collected. The computed tomography (CT) signs of PILA (interlobular septal thickening [ILST], intralobular interstitial thickening [ILIT], ground-glass opacity [GGO], reticular shadow [RS], subpleural line [SL]) were evaluated at 6 levels and statistically analyzed. The effects of age, sex, body mass index (BMI), blood pressure (BP), and blood biochemistry parameters on ILST, ILIT, and RS were analyzed by Binary Logistic regression analysis. Significant age differences in PILA were found. None of the 5 PILA CT signs (GGO, ILST, ILIT, RS, and SL) was observed in subjects under 40 years old, while in subjects over 40 years old, the incidence of PILA increased with age. All 5 CT signs of PILA were significantly different among the subjects aged 18 to 49, 50 to 69, and 70 to 79 (P < .05). There was no significant sex difference in PILA. Among age, sex, BMI, BP, and laboratory biochemistry parameters, only age had a significant effect on ILST, ILIT, and RS. LDCT can be used as a noninvasive method to evaluate the PILA. PILA were mainly affected by age, while sex, BMI, BP, and laboratory biochemistry parameters had little effect on PILA. PILA observed before the age of 40 years should be considered an abnormal finding, whereas it is common in individuals over 70.

A Multi-omic Analysis of the Human Lung Reveals Distinct Cell Specific Aging and Senescence Molecular Programs

Age is a major risk factor for lung disease. To understand the mechanisms underlying this association, we characterized the changing cellular, genomic, transcriptional, and epigenetic landscape of lung aging using bulk and single-cell RNAseq (scRNAseq) data. Our analysis revealed age-associated gene networks that reflected hallmarks of aging, including mitochondrial dysfunction, inflammation, and cellular senescence. Cell type deconvolution revealed age-associated changes in the cellular composition of the lung: decreased alveolar epithelial cells and increased fibroblasts and endothelial cells. In the alveolar microenvironment, aging is characterized by decreased AT2B cells and reduced surfactant production, a finding that was validated by scRNAseq and IHC. We showed that a previously reported senescence signature, SenMayo, captures cells expressing canonical senescence markers. SenMayo signature also identified cell-type specific senescence-associated co-expression modules that have distinct molecular functions, including ECM regulation, cell signaling, and damage response pathways. Analysis of somatic mutations showed that burden was highest in lymphocytes and endothelial cells and was associated with high expression of senescence signature. Finally, aging and senescence gene expression modules were associated with differentially methylated regions, with inflammatory markers such as IL1B, IL6R, and TNF being significantly regulated with age. Our findings provide new insights into the mechanisms underlying lung aging and may have implications for the development of interventions to prevent or treat age-related lung diseases.

S1P lyase inhibition prevents lung injury following high pressure-controlled mechanical ventilation in aging mice

Ventilator-induced Lung Injury (VILI) is characterized by hypoxia, inflammatory cytokine influx, loss of alveolar barrier integrity, and decreased lung compliance. Aging influences lung structure and function and is a predictive factor in the severity of VILI; however, the mechanisms of aging that influence the progression or increased susceptibility remain unknown. Aging impacts immune system function and may increase inflammation in healthy individuals. Recent studies suggest that the bioactive sphingolipid mediator sphingosine-1-phosphate (S1P) and the enzyme that degrades it S1P lyase (SPL) may be involved in lung pathologies including acute lung injury. It is unknown whether aging influences S1P and SPL expression that have been implicated in lung inflammation, injury, and cell apoptosis. We hypothesized that aging and injurious mechanical ventilation synergistically impair S1P levels and enhance S1P lyase (SPL) expression that amplifies alveolar barrier damage and diminishes pulmonary function. Young (2-3 mo) and old (20-25 mo) C57BL/6 mice were mechanically ventilated for 2 h using pressure-controlled mechanical ventilation (PCMV) at 45 cmH2O and 35 cmH2O, respectively. We assessed the impact of aging and PCMV on several indications of acute lung injury, immune cell recruitment, S1P levels and SPL activity. Furthermore, we evaluated the protective effects of inhibiting SPL by tetrahydroxybutylimidazol (THI) administration on the negative outcomes associated with aging and mechanical injury. PCMV exacerbated lung injury in old mice and increased neutrophil influx that was further exacerbated due to aging. SPL expression increased in the young and old ventilated mice and the old nonventilated group. THI treatment reduced several of the indicators of lung injury and resulted in elevated S1P levels in lung tissue and plasma from mice that were injured from mechanical ventilation. CD80 and CD206 activation markers of alveolar and interstitial macrophages were also influenced by THI. SPL inhibition may be a viable therapeutic approach for patients requiring mechanical ventilation by preventing or regulating the exaggerated inflammatory response and reducing lung injury.

MyMD-1 Improves Health Span and Prolongs Life Span in Old Mice: A Noninferiority Study to Rapamycin

Aging and age-related diseases represent a compelling therapeutic goal for senolytics and drugs targeting inflammatory or metabolic pathways. We compared MyMD-1, a synthetic derivative of the alkaloid myosmine capable of suppressing TNF-α production, to rapamycin, the best characterized drug endowed with antiaging properties. In vivo, a longitudinal cohort of 54 C57BL/6 mice, 19-month-old at the start, was randomized to receive MyMD-1, high-dose (126 ppm) rapamycin, or low-dose (14 ppm) rapamycin plus metformin. Each treatment arm included 18 mice (10 females and 8 males) and was followed for 16 months or until death. Life span was significantly longer in MyMD-1 than rapamycin (p = .019 vs high-dose and .01 vs low-dose) in a Cox survival model that accounted for sex and serum levels of IL-6, TNF-α, and IL-17A. MyMD-1 also improved several health span characteristics, resulting in milder body weight loss, greater muscle strength, and slower progression to frailty. In vitro, MyMD-1 and rapamycin were compared using a panel of 12 human primary cell systems (BioMAP Diversity PLUS), where a total of 148 biomarkers were measured. MyMD-1 possessed antiproliferative, anti-inflammatory, and antifibrotic properties. Many were shared with rapamycin, but MyMD-1 was more active in the inhibition of proinflammatory and profibrotic biomarkers. Overall, MyMD-1 emerges as a new compound that, even when begun at an advanced age, induces beneficial effects on health and life span by modulating inflammation and tissue remodeling.

Age-Related Changes in Extracellular Matrix

Extracellular matrix (ECM) is an extracellular tissue structure that, in addition to mechanical support to the cell, is involved in regulation of many cellular processes, including chemical transport, growth, migration, differentiation, and cell senescence. Age-related changes in the structure and composition of the matrix and increase of ECM stiffness with age affect functioning of many tissues and contribute to the development of various pathological conditions. This review considers age-related changes of ECM in various tissues and organs, in particular, effect of ECM changes on aging is discussed.

Neutrophilic Pleuritis Is a Severe Complication of Klebsiella pneumoniae Pneumonia in Old Mice

The pathomechanisms underlying the frequently observed fatal outcome of Klebsiella pneumoniae pneumonia in elderly patients are understudied. In this study, we examined the early antibacterial immune response in young mice (age 2-3 mo) as compared with old mice (age 18-19 mo) postinfection with K. pneumoniae. Old mice exhibited significantly higher bacterial loads in lungs and bacteremia as early as 24 h postinfection compared with young mice, with neutrophilic pleuritis nearly exclusively developing in old but not young mice. Moreover, we observed heavily increased cytokine responses in lungs and pleural spaces along with increased mortality in old mice. Mechanistically, Nlrp3 inflammasome activation and caspase-1-dependent IL-1β secretion contributed to the observed hyperinflammation, which decreased upon caspase-1 inhibitor treatment of K. pneumoniae-infected old mice. Irradiated old mice transplanted with the bone marrow of young mice did not show hyperinflammation or early bacteremia in response to K. pneumoniae. Collectively, the accentuated lung pathology observed in K. pneumoniae-infected old mice appears to be due to regulatory defects of the bone marrow but not the lung, while involving dysregulated activation of the Nlrp3/caspase-1/IL-1β axis.

Advanced age is associated with changes in alveolar macrophages and their responses to the stress of traumatic injury

Alveolar macrophages (AMs) are tissue-resident cells of the lower airways that perform many homeostatic functions critical for pulmonary health and protection against pathogens. However, little is known about the factors that shape AMs during healthy aging. In these studies, we sought to characterize age-related changes in AM phenotype, function, and responses to a physiologic stressor, that is, distal injury. Age was associated with a wide range of changes in cell surface receptor and gene expression by AMs, reflecting a unique alternatively activated phenotype. AMs from aged mice also exhibited markers of cellular senescence along with down-regulation of genes involved in growth and cell cycle pathways relative to young controls. Furthermore, AMs from aged mice showed a stunted transcriptional response to distal injury compared with AMs from young mice. Many changes were found to involve glucocorticoid-regulated genes, and corticosteroid treatment of primary AMs ex vivo revealed diminished transcriptional responses in cells from aged animals. These results demonstrate that there is a complex age-dependent AM phenotype associated with dysregulated stress hormone signaling that may interfere with AM responses to physiologic stressors and could contribute to AM dysfunction and the decline of pulmonary immunity during healthy aging.

A Double-blind, Placebo-controlled, Randomized, Single Ascending, and Multiple Dose Phase 1 Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of Oral Dose Isomyosamine Capsules in Healthy Adult Subjects

BACKGROUND

Aging is tightly linked to chronic disease, frailty, and death. Multi-morbidity, defined as the presence in the same patient of three or more conditions such as neoplastic, cardiovascular, neurodegenerative, metabolic, or autoimmune diseases, becomes more common with age.

METHODS

The study was performed in a double-blind fashion. Subjects within each dose cohort (Cohorts 1, 2, 3, and 4) were randomly assigned to receive Isomyosamine doses (between 150 mg to 600 mg or placebo) or placebo in a 3:1 ratio (6 active: 2 placebo).

RESULTS

Isomyosamine single daily doses each of 150 mg, 300 mg, and 450 mg for 3 days and multiple daily doses of 600 mg for 6 days were safe and well tolerated in healthy subjects. In one dose group, there was a decrease in TNF-α levels found in Isomyosamine treated subjects, but no change in the levels in subjects given placebo. The increase in Isomyosamine exposure was proportional to dose across the dose range of 300 mg to 600 mg when administered as a single dose. There was minimal accumulation of Isomyosamine following 5 days of once daily dosing of Isomyosamine 600 mg. Isomyosamine half-life ranged from approximately 15 minutes to 45 minutes across all doses in the single ascending dose and multiple ascending dose portion of the study. Elimination of Isomyosamine included the renal pathway as a minor route.

CONCLUSION

Isomyosamine will continue to be investigated in phase 2 clinical trials for the treatment of sarcopenia/frailty, hashimoto's thyroiditis and rheumatoid arthritis.

Immunosenescence, Inflammaging, and Lung Senescence in Asthma in the Elderly

Prevalence of asthma in older adults is growing along with increasing global life expectancy. Due to poor clinical consequences such as high mortality, advancement in understanding the pathophysiology of asthma in older patients has been sought to provide prompt treatment for them. Age-related alterations of functions in the immune system and lung parenchyma occur throughout life. Alterations with advancing age are promoted by various stimuli, including pathobionts, fungi, viruses, pollutants, and damage-associated molecular patterns derived from impaired cells, abandoned cell debris, and senescent cells. Age-related changes in the innate and adaptive immune response, termed immunosenescence, includes impairment of phagocytosis and antigen presentation, enhancement of proinflammatory mediator generation, and production of senescence-associated secretory phenotype. Immnunosenescence could promote inflammaging (chronic low-grade inflammation) and contribute to late-onset adult asthma and asthma in the elderly, along with age-related pulmonary disease, such as chronic obstructive pulmonary disease and pulmonary fibrosis, due to lung parenchyma senescence. Aged patients with asthma exhibit local and systemic type 2 and non-type 2 inflammation, associated with clinical manifestations. Here, we discuss immunosenescence’s contribution to the immune response and the combination of type 2 inflammation and inflammaging in asthma in the elderly and present an overview of age-related features in the immune system and lung structure.

The association between small airway dysfunction and aging: a cross-sectional analysis from the ECOPD cohort

BACKGROUND

Aging has been evidenced to bring about some structural and functional lung changes, especially in COPD. However, whether aging affects SAD, a possible precursor of COPD, has not been well characterized.

OBJECTIVE

We aimed to comprehensively assess the relationship between aging and SAD from computed tomography, impulse oscillometry, and spirometry perspectives in Chinese.

METHODS

We included 1859 participants from ECOPD, and used a linear-by-linear association test for evaluating the prevalence of SAD across various age subgroups, and multivariate regression models for determining the impact of age on the risk and severity of SAD. We then repeated the analyses in these subjects stratified by airflow limitation.

RESULTS

The prevalence of SAD increases over aging regardless of definitional methods. After adjustment for other confounding factors, per 10-yrs increase in age was significantly associated with the risk of CT-defined SAD (OR 2.57, 95% CI 2.13 to 3.10) and the increase in the severity of air trapping (β 2.09, 95% CI - 0.06 to 4.25 for LAA_-856), airway reactance (β - 0.02, 95% CI - 0.04 to - 0.01 for X5; β 0.30, 95% CI 0.13 to 0.47 for AX; β 1.75, 95% CI 0.85 to 2.66 for Fres), as well as the decrease in expiratory flow rates (β - 3.95, 95% CI - 6.19 to - 1.71 for MMEF%predicted; β - 5.42, 95% CI - 7.88 to - 2.95 for FEF₅₀%predicted) for SAD. All these associations were generally maintained in SAD defined by IOS or spirometry. After stratification of airflow limitation, we further found that the effect of age on LAA_-856 was the most significant among almost all subgroups.

CONCLUSIONS

Aging is significantly associated with the prevalence, increased risk, as well as worse severity of SAD. CT may be a more optimal measure to assess aging-related SAD. The molecular mechanisms for the role of aging in SAD need to be explored in the future. Trial registration Chinese Clinical Trial Registry ChiCTR1900024643. Registered on 19 July 2019.

Serum Immunoglobulins, Pneumonia Risk, and Lung Function in Middle-Aged and Older Individuals: A Population-Based Cohort Study

Introduction

Immunoglobulins (Igs) play a pivotal role in host defense and prevention of pneumonia. Aging influences serum Ig levels, but the association between Igs and pneumonia in community-dwelling older individuals remains unknown. We evaluated the association of serum IgA, IgG, and IgM with pneumonia and lung function in middle-aged and older individuals.

Methods

We performed Cox and negative binomial regression analyses for the association of Igs with incident pneumonia and pneumonia-related mortality, and recurrent pneumonia respectively. We performed logistic regression analyses for the association between Igs and lung function values. Associations were adjusted for age, sex, smoking, comorbidities, and serum C-reactive protein.

Results

We included 8,766 participants (median age 62.2 years, 57% women, median follow-up 9.8 years). Higher IgA (hazard ratio [HR]: 1.15; 95% confidence interval [95% CI]: 1.00-1.32) and IgG (HR: 1.13; 95% CI: 1.06-1.19) were associated with an increased pneumonia risk. Higher IgG was associated with an increased risk of pneumonia-related mortality (HR: 1.08; 95% CI: 1.01-1.16) and recurrent pneumonia (incidence rate ratio: 1.04; 95% CI: 1.00-1.09). Higher IgA and IgG were also associated with lower forced expiratory volume in one second (FEV₁), lower forced vital capacity (FVC), and an increased odds of preserved ratio impaired spirometry (PRISm, i.e. FEV₁ <80% and FEV₁/FVC ratio ≥70%). No association was seen with an obstructive spirometry pattern.

Discussion

Higher serum IgA and IgG levels were associated with pneumonia, pneumonia-related mortality, and PRISm in middle-aged and older individuals from the general population. Future studies should validate our findings and elucidate underlying pathophysiology.

Genomic DNA hydroxymethylation reveals potential role in identification of lung injury in coal-burning arsenicosis populations

Arsenic (As) is a toxic metalloid element that causes lung cancer and multiple non-malignant respiratory diseases. The toxicity of arsenic is mediated in part by epigenetic mechanisms, such as alterations in DNA methylation. While increasing studies have highlighted the potential importance of arsenic exposure to DNA methylation patterns and the subsequent risks for arsenic toxicity, there has been little focus on DNA hydroxymethylation-a negative regulation mechanism of DNA methylation. Therefore, this study aimed to investigate the relationship between genomic DNA methylation/hydroxymethylation and lung injury in arsenicosis populations. First, an increased risk of lung injury and exacerbation of lung function impairment in the arsenicosis population was confirmed. Levels of 5-methylcytosine/deoxycytidine (5 mC/dC), 5-hydroxymethylcytosine/deoxycytidine (5 hmC/dC) and 5 hmC/5 mC in genomic DNA of peripheral blood were decreased in the arsenicosis population compared to in the control. Additionally, multivariate logistic regression models showed an increased risk of chest digital radiography (DR) abnormalities when 5 hmC/dC and 5 hmC/5 mC levels were lower (OR = 3.12 and 3.96, all P < 0.001). For 3 years follow-up, regression analysis showed that a decline in 5 hmC/dC was significantly associated with the decline of lung function parameters [forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and maximal mid-expiratory flow (MMEF); β = 0.167, 0.122 and 0.073, respectively; all P < 0.05]. Using the receiver operating characteristic (ROC) curve, a combination of 5 hmC/5 dC and 5 hmC/5 mC obtained the highest value for distinguishing lung injury in all subjects (AUC = 0.82, P < 0.01). In contrast, in arsenicosis subjects, 5 hmC/dC was better at distinguishing lung injury (AUC = 0.84, P < 0.01). Together, the results revealed that a decrease in genomic DNA hydroxymethylation markers was associated with lung injury in coal-burning arsenicosis populations. Genomic DNA hydroxymethylation could be a novel biomarker for identifying the risk of lung injury caused by coal-burning arsenicosis.

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.

Effect of different conditioning methods of traditional Chinese health exercise on lung function in healthy middle-aged and elderly people: study protocol for a randomized controlled trial

Background

Lung function is highly age-dependent as it decreases in varying degrees with age, even in healthy people. Decreased lung function results in less elastic lung tissue, reduced chest wall compliance, reduced area for gas exchange, and even a variety of chronic diseases. Traditional Chinese health exercise (TCHE) has three components: “breath regulation,” “body regulation,” and “heart regulation,” which play an important role in the improvement of lung function. However, which component has the most significant effect on lung functioning remains unclear. Therefore, depending on the modality of conditioning, TCHEs will be divided into three exercise intervention groups: breath regulation group, body regulation group, and heart regulation group, in order to explore the magnitude of the effect of the different modalities of conditioning on the improvement of lung function.

Methods

The prospective, parallel, single-blind, randomized controlled trial will evaluate the effects of different conditioning methods of TCHE on lung function in middle-aged and elderly people. The study subjects are healthy middle-aged and elderly adults, who will be randomly divided into the “breath regulation group,” “body regulation group,” “heart regulation group,” and “control group.” The control group will receive health education. Health education and exercise intervention in the three intervention groups will be provided for 6 months, 5 times a week, with each session lasting 60 min. The outcomes of interest include changes in the pulmonary function tests measured at baseline and 3 and 6 months after the beginning of the intervention. The primary outcome is the forced vital capacity (FVC), while the secondary outcomes include forced expiratory volume in 1 s (FEV1), FVC/FEV1 ratio, vital capacity (VC), and maximal voluntary ventilation (MVV).

Discussion

This study will assess the effects of different conditioning methods of TCHE on lung function in middle-aged and elderly people. The final findings of this study will validate the effectiveness and safety of TCHE on lung function interventions in middle-aged and elderly people.

Trial registration

China Clinical Trial Registry ChiCTR2100052687. Registered on November 3, 2021

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05980-5.

Respiratory Function and Muscle Strength Vs. Past Work Type: a Cross-Sectional Study Among Retirees

Objectives

The aim of this cross-sectional study was to assess the effects of past occupational activity on muscle strength and respiratory function among retirees.

Methods

A total of 205 community-dwelling older adults participated in the study. Age (≥60 years) and cessation of professional activity (retirement) constituted the inclusion criteria. The International Standardized Classification of Occupations (ISCO-08) was used to stratify the participants into white- or blue-collar groups. Forced vital capacity (FVC), forced expiratory volume (FEV) in the first second, inspiratory vital capacity (IVC) parameters, and hand grip strength were tested.

Results

Statistically significant differences in IVC and FVC scores were found in white- and blue-collar workers after adjusting for sex and age (ANCOVA). White-collar men had significantly higher IVC as compared to blue-collar men.

Conclusions

Blue-collar male workers may be prone to deteriorating respiratory function in older age. It is vital to promote physical activity and educate blue-collar workers about the need to use respiratory protective equipment.

Innate Receptors Expression by Lung Nociceptors: Impact on COVID-19 and Aging

The lungs are constantly exposed to non-sterile air which carries harmful threats, such as particles and pathogens. Nonetheless, this organ is equipped with fast and efficient mechanisms to eliminate these threats from the airways as well as prevent pathogen invasion. The respiratory tract is densely innervated by sensory neurons, also known as nociceptors, which are responsible for the detection of external stimuli and initiation of physiological and immunological responses. Furthermore, expression of functional innate receptors by nociceptors have been reported; however, the influence of these receptors to the lung function and local immune response is poorly described. The COVID-19 pandemic has shown the importance of coordinated and competent pulmonary immunity for the prevention of pathogen spread as well as prevention of excessive tissue injury. New findings suggest that lung nociceptors can be a target of SARS-CoV-2 infection; what remains unclear is whether innate receptor trigger sensory neuron activation during SARS-CoV-2 infection and what is the relevance for the outcomes. Moreover, elderly individuals often present with respiratory, neurological and immunological dysfunction. Whether aging in the context of sensory nerve function and innate receptors contributes to the disorders of these systems is currently unknown. Here we discuss the expression of innate receptors by nociceptors, particularly in the lungs, and the possible impact of their activation on pulmonary immunity. We then demonstrate recent evidence that suggests lung sensory neurons as reservoirs for SARS-CoV-2 and possible viral recognition via innate receptors. Lastly, we explore the mechanisms by which lung nociceptors might contribute to disturbance in respiratory and immunological responses during the aging process.

The Impact of Lifetime Work and Non-work Physical Activity on Physical Fitness Among White – and Blue – Collar Retirees: A Cross-Sectional Study

Objective: The literature offers significant amount of data on the effects of occupational activity on health, with a distinct link between retirement and health among the most frequently tackled topics. Studies on the relationship between past occupational activity and physical fitness among older retirees remain scarce. The aim of the study was to assess the effects of physical activity on physical fitness in white- and blue-collar retirees.

Methods: A total of 200 participants (aged ≥60) were included in the study. Lifetime physical activity was assessed using the Lifetime Physical Activity Questionnaire. Mean MET/week/year values of total Physical Activity and for each domain separately (occupational, sports, household) were calculated. Participants were stratified to blue- or white- collar group. Physical performance, hand-grip strength (HGS) and pulmonary function were assessed.

Results: Mean total MET/week/year values for the blue- and the white-collar workers were 140.48 ± 55.13 and 100.75 ± 35.98, respectively. No statistically significant differences in physical performance scores were found between the white- and blue- collar groups. Adjustment for age, sex weight and height revealed a statistically significant association between work-related PA FEV*1 in the blue-collar group. White – collar workers presented higher odds ratio for membership in highest quartile in regard to short physical performance battery test score.

Conclusion: Only minimal association of type of occupation on physical fitness were found despite statistically significant differences between mean intensity and duration of sports- and work-related lifetime physical activity. These findings may indicate that the type of past work is not an independent factor influencing the state of a person in old age. Large-scale investigations with physically fit and unfit participants, are necessary.

Environmental Exposures and Lung Aging: Molecular Mechanisms and Implications for Improving Respiratory Health

PURPOSE OF REVIEW

Inhaled environmental exposures cause over 12 million deaths per year worldwide. Despite localized efforts to reduce environmental exposures, tobacco smoking and air pollution remain the urgent public health challenges that are contributing to the growing prevalence of respiratory diseases. The purpose of this review is to describe the mechanisms through which inhaled environmental exposures accelerate lung aging and cause overt lung disease.

RECENT FINDINGS

Environmental exposures related to fossil fuel and tobacco combustion and occupational exposures related to silica and coal mining generate oxidative stress and inflammation in the lungs. Sustained oxidative stress causes DNA damage, epigenetic instability, mitochondrial dysfunction, and cell cycle arrest in key progenitor cells in the lung. As a result, critical repair mechanisms are impaired, leading to premature destruction of the lung parenchyma. Inhaled environmental exposures accelerate lung aging by injuring the lungs and damaging the cells responsible for wound healing. Interventions that minimize exposure to noxious antigens are critical to improve lung health, and novel research is required to expand our knowledge of therapies that may slow or prevent premature lung aging.

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.

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.

Monocyte as a prognostic marker in patients with idiopathic pulmonary fibrosis

This letter raised some concerns about the study by Karampitsakos et al. in a recent issue of Respiratory Research.

Tongue cleaning in the elderly and its role in the respiratory and swallowing functions: Benefits and medical perspectives

Oral dysfunction, including oral uncleanness and decline in tongue motor function, tongue pressure and swallowing function, precedes frailty. The tongue's dorsum is a reservoir of oral microbiota, desquamated epithelial mucosa and leukocytes due to the multi-papillate anatomy, and leads to tongue coating. The tongue coating is frequently found in older adults because of hyposalivation, immunity's hypoactivity, diminished motor function and compromised tongue's pressure with age. Anaerobe-driven volatile sulphur compounds in tongue coating are a major cause of intra-oral malodor. Dysbiosis of the tongue-coating microbiome rather than the amount of microorganisms is associated with a risk of aspiration pneumonia. Daily tongue cleaning with a brush or scraper is an easy way to control tongue coating deposits and quality. Using mouth wash or rinse-containing germicides is also a way to control the microbiota of tongue coating. The tongue function is closely related to swallowing. Tongue and suprahyoid muscles are linked with respiratory muscles through the endothoracic fascia. The mechanical stimulation during the cleaning of the tongue may stimulate the respiratory muscles. An intervention trial revealed that tongue cleaning by mucosal brush improves tongue pressure, swallowing and respiratory function in old residents of nursing homes, suggesting a rehabilitative effect of tongue cleaning on the swallowing and respiratory functions, preventing aspiration pneumonia. This narrative review assesses the tongue-cleaning benefits for respiratory and swallowing functions and the possibility of preventing aspiration pneumonia.

Redox Regulation in Aging Lungs and Therapeutic Implications of Antioxidants in COPD

Mammals, including humans, are aerobic organisms with a mature respiratory system to intake oxygen as a vital source of cellular energy. Despite the essentiality of reactive oxygen species (ROS) as byproducts of aerobic metabolism for cellular homeostasis, excessive ROS contribute to the development of a wide spectrum of pathological conditions, including chronic lung diseases such as COPD. In particular, epithelial cells in the respiratory system are directly exposed to and challenged by exogenous ROS, including ozone and cigarette smoke, which results in detrimental oxidative stress in the lungs. In addition, the dysfunction of redox regulation due to cellular aging accelerates COPD pathogenesis, such as inflammation, protease anti-protease imbalance and cellular apoptosis. Therefore, various drugs targeting oxidative stress-associated pathways, such as thioredoxin and N-acetylcysteine, have been developed for COPD treatment to precisely regulate the redox system. In this review, we present the current understanding of the roles of redox regulation in the respiratory system and COPD pathogenesis. We address the insufficiency of current COPD treatment as antioxidants and discuss future directions in COPD therapeutics targeting oxidative stress while avoiding side effects such as tumorigenesis.

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.

Too young to die? How aging affects cellular innate immune responses to influenza virus and disease severity

Influenza is a respiratory viral infection that causes significant morbidity and mortality worldwide. The innate immune cell response elicited during influenza A virus (IAV) infection forms the critical first line of defense, which typically is impaired as we age. As such, elderly individuals more commonly succumb to influenza-associated complications, which is reflected in most aged animal models of IAV infection. Here, we review the important roles of several major innate immune cell populations in influenza pathogenesis, some of which being deleterious to the host, and the current knowledge of how age-associated numerical, phenotypic and functional cell changes impact disease development. Further investigation into age-related modulation of innate immune cell responses, using appropriate animal models, will help reveal how immunity to IAV may be compromised by aging and inform the development of novel therapies, tailored for use in this vulnerable group.

Fibrosis: Sirtuins at the checkpoints of myofibroblast differentiation and profibrotic activity

Fibrotic diseases are still a serious concern for public health, due to their high prevalence, complex etiology and lack of successful treatments. Fibrosis consists of excessive accumulation of extracellular matrix components. As a result, the structure and function of tissues are impaired, thus potentially leading to organ failure and death in several chronic diseases. Myofibroblasts represent the principal cellular mediators of fibrosis, due to their extracellular matrix producing activity, and originate from different types of precursor cells, such as mesenchymal cells, epithelial cells and fibroblasts. Profibrotic activation of myofibroblasts can be triggered by a variety of mechanisms, including the transforming growth factor-β signalling pathway, which is a major factor driving fibrosis. Interestingly, preclinical and clinical studies showed that fibrotic degeneration can stop and even reverse by using specific antifibrotic treatments. Increasing scientific evidence is being accumulated about the role of sirtuins in modulating the molecular pathways responsible for the onset and development of fibrotic diseases. Sirtuins are NAD⁺ -dependent protein deacetylases that play a crucial role in several molecular pathways within the cells, many of which at the crossroad between health and disease. In this context, we will report the current knowledge supporting the role of sirtuins in the balance between healthy and diseased myofibroblast activity. In particular, we will address the signalling pathways and the molecular targets that trigger the differentiation and profibrotic activation of myofibroblasts and can be modulated by sirtuins.

Effect of dermal phthalate levels on lung function tests in residential area near a petrochemical complex

Phthalates can leach into indoor and outdoor airborne particulate matter and dust, which can then be ingested or absorbed and induce lung injury. Dermal phthalate levels can be used as a matrix for exposure direct absorption from air, particle deposition, and contact with contaminated products. However, the association between dermal phthalate levels in skin wipes and lung function tests remains unknown. A total of 397 participants were included. Spirometry measurements of forced expiratory volume in 1 s (FEV1, L) and forced vital capacity (FVC, L) were calculated. Dermal phthalate levels of diethyl phthalate (DMP), diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), butyl benzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP), and diisodecyl phthalate (DiDP) on forehead skin wipes were detected. The one-unit increases in logarithm (log) dermal DnBP (β = - 0.08; 95% CI - 0.16, - 0.003, p = 0.041), BBzP (β = - 0.09; 95% CI - 0.16, - 0.02, p = 0.009), DEHP (β = - 0.07; 95% CI - 0.14, - 0.003, p = 0.042), and DiNP (β = - 0.08; 95% CI - 0.15, - 0.02, p = 0.017) were significantly associated with decreases in FVC. For elderly participants, one-unit increases in log dermal DnBP (β = - 0.25; 95% CI - 0.46, - 0.04, p = 0.021), BBzP (β = - 0.17; 95% CI - 0.33, - 0.01, p = 0.042), and DiDP (β = - 0.19; 95% CI - 0.39, < 0.01, p = 0.052) were associated with decreases in FEV1. In conclusion, dermal phthalate levels were significantly associated with decreases in lung function tests.

Exposure to TiO2 Nanostructured Aerosol Induces Specific Gene Expression Profile Modifications in the Lungs of Young and Elderly Rats

Although aging is associated with a higher risk of developing respiratory pathologies, very few studies have assessed the impact of age on the adverse effects of inhaled nanoparticles. Using conventional and transcriptomic approaches, this study aimed to compare in young (12–13-week-old) and elderly (19-month-old) fisher F344 rats the pulmonary toxicity of an inhaled nanostructured aerosol of titanium dioxide (TiO₂). Animals were nose-only exposed to this aerosol at a concentration of 10 mg/m³ for 6 h per day, 5 days per week for 4 weeks. Tissues were collected immediately (D0), and 28 days after exposure (D28). A pulmonary influx of neutrophilic granulocytes was observed in exposed rats at D0, but diminished with time while remaining significant until D28. Similarly, an increased expression of several genes involved in inflammation at the two post-exposure time-points was seen. Apart from an age-specific pulmonary influx of lymphocyte, only slight differences in physio-pathological responses following TiO₂ exposure between young and elderly animals were noticed. Conversely, marked age-related differences in gene expression profiles were observed making possible to establish lists of genes specific to each age group and post-exposure times. These results highlight different signaling pathways that were disrupted in rats according to their age.

Insights Into the Effects of Mucosal Epithelial and Innate Immune Dysfunction in Older People on Host Interactions With Streptococcus pneumoniae

In humans, nasopharyngeal carriage of Streptococcus pneumoniae is common and although primarily asymptomatic, is a pre-requisite for pneumonia and invasive pneumococcal disease (IPD). Together, these kill over 500,000 people over the age of 70 years worldwide every year. Pneumococcal conjugate vaccines have been largely successful in reducing IPD in young children and have had considerable indirect impact in protection of older people in industrialized country settings (herd immunity). However, serotype replacement continues to threaten vulnerable populations, particularly older people in whom direct vaccine efficacy is reduced. The early control of pneumococcal colonization at the mucosal surface is mediated through a complex array of epithelial and innate immune cell interactions. Older people often display a state of chronic inflammation, which is associated with an increased mortality risk and has been termed 'Inflammageing'. In this review, we discuss the contribution of an altered microbiome, the impact of inflammageing on human epithelial and innate immunity to S. pneumoniae, and how the resulting dysregulation may affect the outcome of pneumococcal infection in older individuals. We describe the impact of the pneumococcal vaccine and highlight potential research approaches which may improve our understanding of respiratory mucosal immunity during pneumococcal colonization in older individuals.

Implications for Extracellular Matrix Interactions With Human Lung Basal Stem Cells in Lung Development, Disease, and Airway Modeling

The extracellular matrix (ECM) is not simply a quiescent scaffold. This three-dimensional network of extracellular macromolecules provides structural, mechanical, and biochemical support for the cells of the lung. Throughout life, the ECM forms a critical component of the pulmonary stem cell niche. Basal cells (BCs), the primary stem cells of the airways capable of differentiating to all luminal cell types, reside in close proximity to the basolateral ECM. Studying BC-ECM interactions is important for the development of therapies for chronic lung diseases in which ECM alterations are accompanied by an apparent loss of the lung's regenerative capacity. The complexity and importance of the native ECM in the regulation of BCs is highlighted as we have yet to create an in vitro culture model that is capable of supporting the long-term expansion of multipotent BCs. The interactions between the pulmonary ECM and BCs are, therefore, a vital component for understanding the mechanisms regulating BC stemness during health and disease. If we are able to replicate these interactions in airway models, we could significantly improve our ability to maintain basal cell stemness ex vivo for use in in vitro models and with prospects for cellular therapies. Furthermore, successful, and sustained airway regeneration in an aged or diseased lung by small molecules, novel compounds or via cellular therapy will rely upon both manipulation of the airway stem cells and their immediate niche within the lung. This review will focus on the current understanding of how the pulmonary ECM regulates the basal stem cell function, how this relationship changes in chronic disease, and how replicating native conditions poses challenges for ex vivo cell culture.

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 emerging role of the sympathetic nervous system in skeletal muscle motor innervation and sarcopenia

Examining neural etiologic factors'role in the decline of neuromuscular function with aging is essential to our understanding of the mechanisms underlying sarcopenia, the age-dependent decline in muscle mass, force and power. Innervation of the skeletal muscle by both motor and sympathetic axons has been established, igniting interest in determining how the sympathetic nervous system (SNS) affect skeletal muscle composition and function throughout the lifetime. Selective expression of the heart and neural crest derivative 2 gene in peripheral SNs increases muscle mass and force regulating skeletal muscle sympathetic and motor innervation; improving acetylcholine receptor stability and NMJ transmission; preventing inflammation and myofibrillar protein degradation; increasing autophagy; and probably enhancing protein synthesis. Elucidating the role of central SNs will help to define the coordinated response of the visceral and neuromuscular system to physiological and pathological challenges across ages. This review discusses the following questions: (1) Does the SNS regulate skeletal muscle motor innervation? (2) Does the SNS regulate presynaptic and postsynaptic neuromuscular junction (NMJ) structure and function? (3) Does sympathetic neuron (SN) regulation of NMJ transmission decline with aging? (4) Does maintenance of SNs attenuate aging sarcopenia? and (5) Do central SN group relays influence sympathetic and motor muscle innervation?

Mathematical modeling of ventilator-induced lung inflammation

Despite the benefits of mechanical ventilators, prolonged or misuse of ventilators may lead to ventilation-associated/ventilation-induced lung injury (VILI). Lung insults, such as respiratory infections and lung injuries, can damage the pulmonary epithelium, with the most severe cases needing mechanical ventilation for effective breathing and survival. Damaged epithelial cells within the alveoli trigger a local immune response. A key immune cell is the macrophage, which can differentiate into a spectrum of phenotypes ranging from pro- to anti-inflammatory. To gain a greater understanding of the mechanisms of the immune response to VILI and post-ventilation outcomes, we developed a mathematical model of interactions between the immune system and site of damage while accounting for macrophage phenotype. Through Latin hypercube sampling we generated a collection of parameter sets that are associated with a numerical steady state. We then simulated ventilation-induced damage using these steady state values as the initial conditions in order to evaluate how baseline immune state and lung health affect outcomes. We used a variety of methods to analyze the resulting parameter sets, transients, and outcomes, including a random forest decision tree algorithm and parameter sensitivity with eFAST. Analysis shows that parameters and properties of transients related to epithelial repair and M1 activation are important factors. Using the results of this analysis, we hypothesized interventions and used these treatment strategies to modulate the response to ventilation for particular parameters sets.

Twist1 signaling in age-dependent decline in angiogenesis and lung regeneration

Angiogenesis – the formation of new blood capillaries- is impaired in aging animals and contributes to the pathogenesis of age-related diseases. A transcription factor, Twist1, contributes to the pathogenesis of age- and angiogenesis-related diseases such as pulmonary fibrosis and atherosclerosis. However, the mechanism by which Twist1 controls age-dependent decline in angiogenesis remains unclear. In this report, we have demonstrated that the levels of Twist1 are higher, while the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) that stimulates angiogenesis, is lower in endothelial cells (ECs) isolated from aged human adipose tissues and mouse lungs compared to those from young tissues. Knockdown of Twist1 in aged human ECs increases the levels of PGC1α and angiogenic factor receptor, vascular endothelial growth factor receptor (VEGFR2), and restores EC proliferation and migration, while inhibition of PGC1α suppresses these effects. Knockdown of Twist1 in supplemented aged ECs also restores vascular networks in the subcutaneously implanted gel, while these effects are abrogated by knockdown of PGC1α. Age-dependent inhibition of post-pneumonectomy (PNX) lung growth is suppressed in Tie2-specific Twist1 conditional knockout mouse lungs, in which VEGFR2 expression increases after PNX. These results suggest that upregulation of endothelial Twist1 mediates age-dependent decline in angiogenesis and regenerative lung growth.

Telomerase treatment prevents lung profibrotic pathologies associated with physiological aging

Short/dysfunctional telomeres are at the origin of idiopathic pulmonary fibrosis (IPF) in patients mutant for telomere maintenance genes. However, it remains unknown whether physiological aging leads to short telomeres in the lung, thus leading to IPF with aging. Here, we find that physiological aging in wild-type mice leads to telomere shortening and a reduced proliferative potential of alveolar type II cells and club cells, increased cellular senescence and DNA damage, increased fibroblast activation and collagen deposits, and impaired lung biophysics, suggestive of a fibrosis-like pathology. Treatment of both wild-type and telomerase-deficient mice with telomerase gene therapy prevented the onset of lung profibrotic pathologies. These findings suggest that short telomeres associated with physiological aging are at the origin of IPF and that a potential treatment for IPF based on telomerase activation would be of interest not only for patients with telomerase mutations but also for sporadic cases of IPF associated with physiological aging.

Tongue cleaning maintains respiratory function in older individuals: A 1-year randomised controlled trial

OBJECTIVE

The aim of this 1-year longitudinal randomised controlled trial was to evaluate the effectiveness of tongue cleaning on the maintenance of respiratory function in older adults requiring care.

METHODS

The participants included 24 residents of two nursing homes in Kitakyushu, Japan. The participants were randomised to receive tongue cleaning with routine oral care (intervention group, n = 12), or routine oral care alone (control group, n = 12). Among the participants, three in the intervention group and four in the control group had cerebrovascular disease history, four in the intervention group and four in the control group had a history of cardiac disease, and five in the intervention group and four in the control group were without medical history. Respiratory function was assessed on the basis of the peak expiratory flow rate (PEFR). Tongue pressure, swallowing function, oral health status, activities of daily living and nutritional status were also measured at baseline and at the end of the 1-year follow-up period.

RESULTS

The number of analysed participants in each group was 12. In the control group, the PEFR (1.6 [0.4-4.2] L s^-1 vs 1.4 [0.4-3.2] L s^-1 , P = .034) and tongue pressure (16.4 [1.7-35.2] kPa vs 8.0 [1.4-38.6] kPa, P = .032) significantly declined after 1-year. However, the PEFR (1.5 [0.8-2.9] L s^-1 vs 1.6 [0.7-4.2] L s^-1 , P = .366) and tongue pressure (18.1 [4.2-37.1] kPa vs 16.1 [5.2-41] kPa, P = .307) were maintained in the intervention group. The change in the PEFR was significantly greater in the intervention group compared with the control group (0.130 [-0.45-1.70] L s^-1 vs -1.70 [-10.00-10.00] L s^-1 , P = .028).

CONCLUSION

Our findings suggest that tongue cleaning may help maintain tongue and respiratory function in older adults requiring care.

Citrus Alkaline Extracts Inhibit Senescence of A549 Cells to Alleviate Pulmonary Fibrosis via the β-Catenin/P53 Pathway

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is a disease related to aging, which has become increasingly prevalent as the population has aged. However, there remains no effective treatment for the disease. Alveolar epithelial type II cell (AEC II) senescence plays an important role in the occurrence and development of IPF. Therefore, enhancing our understanding of aging AEC IIs might facilitate the development of a new therapeutic strategy for the prevention and treatment of IPF. The aim of this study was to investigate the effect of citrus alkaline extracts (CAE) on senescence in A549 cells and elucidate the mechanism by which CAE function. MATERIAL AND METHODS Adriamycin RD (ARD) induces the senescence of A549 cells. Relevant indicators were identified following administration of 3 concentrations of CAE (50 μg/mL, 100 μg/mL, and 200 μg/mL) to A549 cells. RESULTS CAE inhibited senescence in ARD-induced A549 cells. It inhibited p16, p21, p53, and a senescence-associated secretory phenotype, and reduced expression of the senescence-related positive cells of ß-galactosidase. Further study revealed that activation of the ß-catenin signaling pathway is closely associated with p53. CAE inhibited senescence in A549 cells via the ß-catenin/p53 pathway. Further, inhibition of b-catenin was associated with reduced expression levels of p53 and p21, and the anti-aging effects of CAE were enhanced. When expression of p53 was inhibited, expression levels of ß-catenin also tended to decrease. CONCLUSIONS In summary, our study showed that CAE can inhibit aging in A549 cells to alleviate pulmonary fibrosis, and thus limit the secretion of the extracellular matrix and collagen in lung fibroblasts.

Tissue-Specific Landscape of Metabolic Dysregulation during Ageing

The dysregulation of cellular metabolism is a hallmark of ageing. To understand the metabolic changes that occur as a consequence of the ageing process and to find biomarkers for age-related diseases, we conducted metabolomic analyses of the brain, heart, kidney, liver, lung and spleen in young (9-10 weeks) and old (96-104 weeks) wild-type mice [mixed genetic background of 129/J and C57BL/6] using NMR spectroscopy. We found differences in the metabolic fingerprints of all tissues and distinguished several metabolites to be altered in most tissues, suggesting that they may be universal biomarkers of ageing. In addition, we found distinct tissue-clustered sets of metabolites throughout the organism. The associated metabolic changes may reveal novel therapeutic targets for the treatment of ageing and age-related diseases. Moreover, the identified metabolite biomarkers could provide a sensitive molecular read-out to determine the age of biologic tissues and organs and to validate the effectiveness and potential off-target effects of senolytic drug candidates on both a systemic and tissue-specific level.

Factors associated with self-assessed asthma severity

BACKGROUND

Asthma severity can be estimated as the level of medication needed to achieve asthma control or by the patient's subjective assessment. Factors associated with self-assessed asthma severity are still incompletely explored.

AIM

The aim was to study factors associated with self-assessed moderate or severe asthma.

METHOD

In total, 1828 randomly selected asthma patients from primary (69%) and secondary (31%) care, completed a questionnaire including items about patient characteristics, comorbidity, the Asthma Control Test (ACT), emergency care visits and a scale for self-assessed asthma severity. Logistic regression was used to analyze associations with the dependent variable, self-assessed moderate or severe asthma in the entire study population and stratified by sex.

RESULTS

Of the patients, 883 (45%) reported having moderate or severe asthma. Factors independently associated with self-assessed moderate or severe asthma were age >60 years (OR [95% CI] 1.98 [1.37-2.85]), allergic rhino-conjunctivitis (1.43 [1.05-1.95]), sinusitis (1.45 [1.09-1.93]), poor asthma control as measured by ACT <20 (5.64 [4.45-7.16]) and emergency care visits the previous year (2.52 [1.90-3.34]). Lower level of education was associated with self-assessed moderate/severe asthma in women (1.16 [1.05-2.43]) but not in men (0.90 [0.65-1.25]), p for interaction = .012.

CONCLUSION

Poor asthma control, allergic rhino-conjunctivitis, recent sinusitis and older age were independently associated with self-assessed moderate or severe asthma. Important implications are that comorbid conditions of the upper airways should always be considered as part of asthma management, and that elderly patients may need extra attention.