Aging and Susceptibility to Pulmonary Disease

Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune-driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence-related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging.

Transcriptomic profiles of age-related genes in female trachea and bronchus

Background: Studies demonstrated that age-related cellular and functional changes of airway significantly contribute to the pathogenesis of many airway diseases. However, our understanding on the age-related molecular alterations of human airway remains inadequate.

Methods: Airway (trachea and bronchus) brushing specimens were collected from 14 healthy, female non-smokers with ages ranging from 20 to 60 years. Bulk RNA sequencing was performed on all the specimens (n = 28). Airway cell types and their relative proportions were estimated using CIBERSORTx. The cell type proportions were compared between the younger (age 20–40) and elder group (age 40–60) in the trachea and bronchus respectively. The linear association between cell type proportion and age was assessed using the Pearson correlation coefficient. Differentially expressed genes (DEGs) between the two age groups were identified using DESeq2. Three kinds of enrichment analysis of the age-related DEGs were performed, including Gene ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and disease enrichment analysis.

Results: Sixteen and thirteen cell types were separately identified in tracheal and bronchial brushings, with the airway epithelial cells (including suprabasal, submucosal gland (SMG) goblet, serous, secretory, multiciliated, cycling.basal, basal cells) accounting for 85.1% in the trachea and 92.5% in the bronchus. The lymphatic cell and NK cells had a higher abundance ratio in the trachea, compared with the bronchus. The proportion of basal cells was negatively related to age both in the trachea and bronchus. Thirty-one and fifty-two age-related DEGs (p < 0.1) were identified in the trachea and bronchus, respectively. Among them, five common DEGs (CXCL2, CXCL8, TCIM, P4HA3, AQP10) were identified. Pathway enrichment analysis showed both tracheal and bronchial age-related DEGs were primarily involved in immune regulatory signaling pathways (TNF, NF-kappa B, IL-17 et al.). Disease enrichment analysis suggested that tracheal age-related DEGs significantly related to asthmatic pulmonary eosinophilia, and chronic airflow obstruction et al., and that bronchial age-related DEGs were enriched in airflow obstruction, bronchiectasis, pulmonary emphysema, and low respiratory tract infection et al.

Conclusion: We found the proportion of basal cells decreased with age in both the trachea and bronchus, suggesting a weakening of their self-renew ability with age. We identified transcriptomic signature genes associated with the early aging process of the human trachea and bronchus, and provided evidence to support that changes in their immune regulatory function may play critical roles in age-related airway diseases.

Ageing and chronic obstructive pulmonary disease: interrelationships

PURPOSE OF REVIEW

As life expectancy increases, the ageing population accrues an increasing burden of chronic conditions and functional compromise. Some conditions that lead to compromise are deemed part of 'natural ageing,' whereas others are considered to represent disease processes. Ageing ('a natural process') and chronic obstructive pulmonary disease ('a disease') share many common features, both pulmonary and systemic. At times, the pathways of injury are the same, and at times they are concurrent. In some cases, age and disease are separated not by the presence but by the severity of a finding or condition. This brief review aims to compare some of the similarities between ageing and COPD and to compare/contrast mechanisms for each.

RECENT FINDINGS

At the cellular level, the natural process of ageing includes multiple systemic and molecular mechanisms. COPD, though defined by progressive pulmonary compromise, can also be a systemic disease/process. It has become evident that specific senescence pathways like p-16 and the sirtuin family of proteins are implicated both in ageing and in COPD. Also common to both ageing and COPD are increased inflammatory markers, leucocyte response abnormalities, and DNA-level abnormalities.

SUMMARY

The prevalence of COPD increases with increasing age. COPD contributes to the accrued burden of chronic disease and is a significant contributor to morbidity and mortality in this population. This review attempts to summarize some of similarities between ageing and COPD and their underlying mechanisms.

Aging conundrum: A perspective for ovarian aging

Progressive loss of physiological integrity and accumulation of degenerative changes leading to functional impairment and increased susceptibility to diseases are the main features of aging. The ovary, the key organ that maintains female reproductive and endocrine function, enters aging earlier and faster than other organs and has attracted extensive attention from society. Ovarian aging is mainly characterized by the progressive decline in the number and quality of oocytes, the regulatory mechanisms of which have yet to be systematically elucidated. This review discusses the hallmarks of aging to further highlight the main characteristics of ovarian aging and attempt to explore its clinical symptoms and underlying mechanisms. Finally, the intervention strategies related to aging are elaborated, especially the potential role of stem cells and cryopreservation of embryos, oocytes, or ovarian tissue in the delay of ovarian aging.