Exercise-Induced Cell-Free DNA Correlates with Energy Expenditure in Multiple Exercise Protocols.

PURPOSE: Exercise-induced cell-free DNA (ei-cfDNA) has been studied in response to various types of exercise. Its correlation with exercise intensity and duration has been observed consistently. However, comprehensive measurements and exploration of the tissue of origin are lacking. The aim of this study is to establish precise connections between exercise variables and the distribution of tissue of origin, aiming to provide further evidence supporting its use as a biomarker for exercise. METHODS: Twelve self-identified active adults (six men and six women) performed a crossover study starting with either endurance testing or resistance testing under different intensities and protocols. We obtained blood before and after each exercise session and measured the levels of cfDNA and determined its tissue of origin utilizing cell type-specific DNA methylation patterns in plasma. RESULTS: We found that when duration and intensity are fixed, ei-cfDNA fold change correlates with energy expenditure ( P = 0.001) in endurance testing and years trained ( P = 0.001) in resistance testing. Most of the ei-cfDNA comes from increases in white blood cells (~95%) where neutrophils make up the majority (~74%) and the distribution is different between exercise modalities and protocols. CONCLUSIONS: This study highlights the potential of exercise-induced cfDNA as a biomarker for exercise, showing correlations with energy expenditure and a consistent pattern of tissue origin. Additional research is needed to investigate potential sex differences in the response of cfDNA to exercise, further exploring its clinical implications.

Elevated cfDNA after exercise is derived primarily from mature polymorphonuclear neutrophils, with a minor contribution of cardiomyocytes.

Strenuous physical exercise causes a massive elevation in the concentration of circulating cell-free DNA (cfDNA), which correlates with effort intensity and duration. The cellular sources and physiological drivers of this phenomenon are unknown. Using methylation patterns of cfDNA and associated histones, we show that cfDNA in exercise originates mostly in extramedullary polymorphonuclear neutrophils. Strikingly, cardiomyocyte cfDNA concentration increases after a marathon, consistent with elevated troponin levels and indicating low-level, delayed cardiac cell death. Physical impact, low oxygen levels, and elevated core body temperature contribute to neutrophil cfDNA release, while muscle contraction, increased heart rate, ß-adrenergic signaling, or steroid treatment fail to cause elevation of cfDNA. Physical training reduces neutrophil cfDNA release after a standard exercise, revealing an inverse relationship between exercise-induced cfDNA release and training level. We speculate that the release of cfDNA from neutrophils in exercise relates to the activation of neutrophils in the context of exercise-induced muscle damage.

Mobile Health Services for COVID-19: Counseling, Testing, and Vaccination for Medically Underserved Populations.

Mobile health units can improve access to preventive health services, especially for medically underserved populations. However, there is little published experience of mobile health units being used to expand access to COVID-19 vaccination. In concert with local public health departments and community members, we implemented a mobile COVID-19 health unit and deployed it to 12 predominantly low-income and racial/ethnic minority communities in Massachusetts. We describe the success and challenges of this innovative program in expanding access to COVID-19 vaccination. (Am J Public Health. 2022;112(11):1556-1559. https://doi.org/10.2105/AJPH.2022.307021).

Expanding COVID-19 vaccine access to underserved populations through implementation of mobile vaccination units.

COVID-19 has disproportionately impacted underserved populations, including racial/ethnic minorities. Prior studies have demonstrated that mobile health units are effective at expanding preventive services for hard-to-reach populations, but this has not been studied in the context of COVID-19 vaccination. Our objective was to determine if voluntary participants who access mobile COVID-19 vaccination units are more likely to be racial/ethnic minorities and adolescents compared with the general vaccinated population. We conducted a cross-sectional study of individuals who presented to three different mobile COVID-19 vaccination units in the Greater Boston area from May 20, 2021, to August 18, 2021. We acquired data regarding the general vaccinated population in the state and of target communities from the Massachusetts Department of Public Health. We used chi-square testing to compare the demographic characteristics of mobile vaccination unit participants and the general state and community populations that received COVID-19 vaccines during the same time period. We found that during this three-month period, mobile vaccination units held 130 sessions and administered 2622 COVID-19 vaccine doses to 1982 unique participants. The median (IQR) age of participants was 31 (16-46) years, 1016 (51%) were female, 1575 (80%) were non-White, and 1126 (57%) were Hispanic. Participants in the mobile vaccination units were more likely to be younger (p < 0.001), non-White race (p < 0.001), and Hispanic ethnicity (p < 0.001) compared with the general vaccinated population of the state and target communities. This study suggests that mobile vaccination units have the potential to improve access to COVID-19 vaccination for diverse populations.