Physical Activity as a Preventive Lifestyle Intervention Acts Through Specific Exosomal miRNA Species—Evidence From Human Short- and Long-Term Pilot Studies

Abstract

Exercise initiates systemic adaptation to promote health and prevent various lifestyle-related chronic diseases. Emerging evidence suggests that circulating exosomes mediate some of the beneficial effects of exercise via the transfer of microRNAs between tissues. Yet to date, a comprehensive profile of the exosomal miRNA (exomiR) content released following short-term (0.5 year in this study) and long-term (25 + years in this study) regular bouts of exercise is still lacking. However, a better understanding of these miRNA species would assist in clarifying the role of regular exercise at the molecular level in the prevention of chronic diseases. In the present pilot studies we analyzed serum exomiR expression in healthy young, sedentary participants (n = 14; age: 23 ± 2 years) at baseline and following a half year-long moderate-intensity regular exercise training. We also analyzed serum exomiR expression in older, healthy trained participants (seniors, n = 11; age: 62 ± 6 years) who engaged in endurance activities for at least 25 years. Following the isolation and enrichment of serum exosomes using Total Exosome Isolation Reagent (TEI) their exomiR levels were determined using the amplification-free Nanostring platform. Hierarchical cluster analysis revealed that the majority of exomiRs overlap for short-term (0.5 year in this study) and long-term (25 + years in this study) regular bouts of exercise. The top 12 significantly altered exomiRs (let-7a-5p; let-7g-5p; miR-130a-3p; miR-142-3p; miR-150-5p; miR-15a-5p; miR-15b-5p; miR-199a-3p; miR-199b-3p; miR-223-3p; miR-23a-3p, and miR-451a-3p) were used for further evaluation. According to KEGG pathway analysis a large portion of the exomiRs target chronic diseases including cancer, neurodegenerative and metabolic diseases, and viral infections. Our results provide evidence that exosomal miRNA modulation is the molecular mechanism through which regular exercise prevents various chronic diseases. The possibility of using such exomiRs to target diseases is of great interest. While further validation is needed, our comprehensive exomiR study presents, for the first time, the disease-preventive molecular pattern of both short and long-term regular exercise.

Exercise Training and Circulating Small Extracellular Vesicles: Appraisal of Methodological Approaches and Current Knowledge

“…Given that the older participants were defined as trained based on their response to the IPAQ rather than objective measures of exercise training history or physical fitness, arguably it is difficult to discern the extent to which these (minor) differences in miRNA were solely the result of divergent exercise training habits. Age and sex may also have been a factor given that the trained cohort in this study were on average ∼39 years older than the sedentary participants and were male as opposed to mostly females in the sedentary group (Garai et al, 2021). The resting profile of circulating small EVs is influenced by biological sex and chronological age (Noren Hooten, 2020) and therefore are likely to be major confounders in these data.…”

“…To our knowledge, there are currently four reports describing the influence of prior exercise training on preparations of circulating small EVs derived from resting humans (Hou et al, 2019;Nair et al, 2020;Estébanez et al, 2021;Garai et al, 2021; Table 2), three of which separated small EVs from plasma (Hou et al, 2019;Nair et al, 2020;Estébanez et al, 2021) and one which has separated small EVs from serum (Garai et al, 2021). The first study reported 1.8-fold greater abundance of miR-342-5p at rest in preparations of small EVs derived from young (19 to 22 years) male rowers with at least 1 year of training experience compared to sedentary controls (n = 16 in each group).…”

“…The final study consisted of two pilot experiments that investigated the potential influence of exercise training on the circulating profile of small EVs at rest (Garai et al, 2021). The first experiment consisted of healthy participants (n = 14; M/F, 2/12) performing a concurrent aerobic and resistance exercise training intervention 3 days per week for 6 months.…”

“…In this experiment, no difference was observed in the number of particles within separated preparations of small EVs via NTA before and after exercise training, although seven miRNA were differentiallyexpressed (all decreased) when analyzed using a NanoString array (Table 2). The second experiment reported in this study was a cross-sectional study in which resting profile of circulating small EVs from older men (aged 62 ± 6 years; n = 11) selfreporting > 25 years of exercise training [and identified as "trained" via their responses to the International Physical Activity Questionnaire (IPAQ; Craig et al, 2003)], was compared to the baseline sedentary samples of the cohort in the first experiment (Garai et al, 2021). Again no difference was observed in the resting abundance of small EVs between the older trained men and younger sedentary individuals via NTA.…”

Treatment with EV-miRNAs Alleviates Obesity-Associated Metabolic Dysfunction in Mice

“…Indeed, during exercise, the muscles secrete a variety of circulating factors, collectively termed “exerkines”, which have been proposed to modulate the function of other tissues in response to exercise [ 11 , 12 ]. Interestingly, exercise also increases the number of small vesicles circulating in the blood [ 13 ] and modifies their cargo—particularly their microRNA (miRNA) content [ 14 ]. miRNAs are small non-coding RNA molecules that act as post-transcriptional repressors of gene expression [ 15 ] and modulate plastic processes—such as metabolic homeostasis—in the face of physiological and pathological stresses [ 16 ].…”