Exploring mechanisms of biological aging in susceptible subjects

The aim of the PhD project is to explore molecular mechanisms that characterize the process of biological aging with the main focus on the two most prominent early hallmarks of biological aging such as telomere length (TL) and epigenetic age, also defined as DNA methylation age (DNAmAge), in order to answer the following main questions: 1) If environmental and occupational exposures accelerate the biological aging in healthy subjects and in subjects affected by age-relate disease. 2) If, on the other hand, correct lifestyle including an intensive meditation/relaxing training in healthy subjects and patients with cardiovascular diseases, and heart transplantation in patients suffering from end-stage heart failure, slow down biological aging. To this aims we analyzed biological aging indicators in easily available human tissue (blood leucocytes) and in target organ (i.e., heart of donors and recipients and lung from induced sputum of Chronic Obstructive Pulmonary Disease (COPD) patients). Study populations consist of: 1) HEALTHY SUBJECTS EXPOSED TO GERONTOGENIC ENVIRONMENTAL AND OCCUPATIONAL EXPOSURES a) 71 night-shift workers and 84 day workers as control exposed to circadian rhythm disruption. b) 585 individuals from general population living in North-East Italy exposed to everyday exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs), which are fundamental constituents of air pollution. c) A prospective cohort study of women and men aged 70 years and older from the area of Treviso, which is characterized by the highest longevity in Italy. TRELONG longitudinal study population comprises 576 subjects at baseline, 300 and 200 subjects at T1 and T2 respectively, exposed to lifestyle and occupational exposures. 2) SUBJECTS AFFECTED BY AGE-RELATE DISEASES a) Bladder cancer (BC), a chronic disease characterized by the interaction between environmental/occupational and genetic risk factors. Study population includes newly diagnosed, histologically confirmed BC patients, admitted to the Urology Departments of two large hospitals from 1997 to 2000. Controls are 94 non-neoplastic urological patients matched to cases by age, period and hospital of admission. b) Idiopathic pulmonary fibrosis (IPF) and Chronic Obstructive Pulmonary Disease (COPD) as the most common manifestations of aging-mediated diseases. Study population consists of n=101 IPF patients (ATS/ERS/JRS/ALAT guidelines) and n=18 moderate COPD patients (GOLD 2019) all enrolled at the ambulatory of Pneumology and Respiratory Physiopathology Wards – Department of Cardiac, Thoracic and Vascular Sciences and Public Health, University of Padova. 3) HEALTHY SUBJECTS AND PATIENTS EXPOSED TO REJUVENATING FACTORS a) Patients after myocardial infarction (n=20) and healthy control individuals (n=10), age- and gender-matched, trained to meditation and relax for 60 days. b) 17 recipients receiving the heart from 17 donors in the period February 2018 - February 2019. The local Ethics Committee - University of Padova, approved the study protocols (3843/AO/16 and 3054/AO/14). Main finding stemming from our results revels that: 1) HEALTHY SUBJECTS EXPOSED TO GERONTOGENIC ENVIRONMENTAL AND OCCUPATIONAL EXPOSURES - Night-shift work is associated with increased systemic inflammation as proved by higher C-reactive protein (CRP) levels among night shift workers. LTL is reduced by CRP, while is positively associated with long pentraxin 3 (PTX3) that, by orchestrating an efficient governance of inflammatory processes, may protect telomere from attrition. This would make nocturnal workers more susceptible to premature LTL shortening and aging. - Certain preventable everyday life exposures to PAHs diminish LTL and even LmtDNAcn, in particular in males, acting through anti-B[a]PDE–DNA adduct formation. Our findings show that indoor activities and diet represent the primary determinants of PAHs exposure in increasing anti-B[a]PDE–DNA adduct levels that in turn decrease in presence of detoxifying GSTM1. - In TRELONG population LTL significantly declines over the years, from baseline to follow up, also considering only n=161 subjects whit all measurements at three different time points. 2) SUBJECTS AFFECTED BY AGE-RELATE DISEASES - LTL attrition is a critical event in BC. In particular, BC risk is increased directly by LTL attrition that depends on some preventable everyday life exposures genetically modulated. Furthermore, indirect effects on BC risk are evidenced via LTL reduction through age and genetic polymorphisms involved in modulating response to environmental exposure. - IPF patients in follow up present an increase in LTL positively related to the duration of antifibrotic treatment, with both pirfenidone and nintedanib, and with a decrease in lung function decline. These results would suggest that telomere shortening in IPF patients treated with antifibrotic drugs may be reversed leading to an increase in LTL. - In COPD patients: a) lung, i.e., pulmonary cells obtained from induced sputum, is biologically older than blood, as determined by TL and DNAmAge; b) blood age acceleration (AgeAcc) defined as the difference between DNAmAge and chronological age, but not TL, highly correlates with lung AgeAcc; c) blood AgeAcc significantly correlates with the main clinical features (CRP and FEV1) of COPD. 3) HEALTHY SUBJECTS AND PATIENTS EXPOSED TO REJUVENATING FACTORS - In healthy subjects but not in patients, DNAmAge is reduced after an intensive relaxing training. Differently, LTL is preserved in healthy subjects, while in patients it continues to decrease. However, the correlation between LTL and chronological age becomes positive after training in both groups. These findings would suggest that intensive relaxing practices influence different aging molecular mechanisms, i.e., DNAmAge and LTL, with a rejuvenating effect. - Biological donors’ heart age is found to be younger than chronological age, suggesting that donors’ cardiac tissues are biologically younger than chronologically measured. Furthermore, biological donors’ left atrium age is 5 years younger than recipients’ left atrium age. This would indicate that patients who underwent heart transplantation have received a younger heart. Further results and comments are described in each work reported in the specific Chapters. Our results contribute to reinforce the concept that biological aging may be modulated by a multiplicity of factors (environmental, occupational, lifestyle) making people more susceptible to premature aging or inducing an accelerated aging or, interestingly, eliciting a rejuvenation effect. In the era of the silver tsunami, identifying gerontogenic and rejuvenating factors is of paramount importance to develop anti-aging strategies for extending the number of healthy years of life.