Abstract
In the last few months, we have been living through an epic public health threat around the globe due to the spread of a novel coronavirus (SARS-CoV-2) that causes coronavirus disease 2019 or COVID-19 (1). COVID-19 is clinically characterized by fever, cough, fatigue, incapacity to breathe, pneumonia/other respiratory tract symptoms, kidney failure, neurological symptoms and even death (1–7). Recent publications have shown that COVID-19 impairs immune system response by severely compromising the number and function of T cells, especially Natural Killer (NK) cells, by increasing the levels of blood C-reactive protein (CRP) and pro-inflammatory cytokines and causing atrophy of spleen and lymph nodes, along with reduced lymphocytes in lymphoid organs (2–7). This immune dysregulation had a fatal outcome mainly in individuals with pre-existing medical conditions and elderly patients (2, 4, 7). According to the United Nations, there were 703 million people aged 65 years or older worldwide in 2019, which implies that about 10% of our world population is at higher risk for negative prognosis under COVID-19 infection. Aging is characterized by several changes, including exacerbated inflammatory responses mediated by the innate immune system with reduced capacity to protect against infections, cancer and wound healing, leading to more severe consequences of bacterial and viral infections and reduced response to vaccination (8). This pro-inflammatory status renders older individuals susceptible to tissue-damaging immunity and chronic inflammatory diseases. Therefore, interventions that can prevent or retard the decline of immunocompetence would have a considerable clinical and public health impact on this parcel of the population. In this scenario, the regular practice of physical activity and physical exercise has been widely prescribed, including for elderly people, since it favors anti-inflammatory status, promoting healthier aging and reducing all-cause mortality (9).
Highlights
In the last few months, we have been living through an epic public health threat around the globe due to the spread of a novel coronavirus (SARS-CoV-2) that causes coronavirus disease 2019 or COVID-19 [1]
Recent publications have shown that COVID-19 impairs immune system response by severely compromising the number and function of T cells, especially Natural Killer (NK) cells, by increasing the levels of blood C-reactive protein (CRP) and pro-inflammatory cytokines and causing atrophy of spleen and lymph nodes, along with reduced lymphocytes in lymphoid organs [2,3,4,5,6,7]
The aging of the immune system seems to be responsible for several comorbidities presented in the elderly, and T cells are highly relevant for adaptive immune responses
Summary
In the last few months, we have been living through an epic public health threat around the globe due to the spread of a novel coronavirus (SARS-CoV-2) that causes coronavirus disease 2019 or COVID-19 [1]. Recent publications have shown that COVID-19 impairs immune system response by severely compromising the number and function of T cells, especially Natural Killer (NK) cells, by increasing the levels of blood C-reactive protein (CRP) and pro-inflammatory cytokines and causing atrophy of spleen and lymph nodes, along with reduced lymphocytes in lymphoid organs [2,3,4,5,6,7]. It has been shown that moderate-intensity cardiovascular exercise executed three times per week for 4 months, prior to viral exposure, improved influenza vaccination responses, with extended duration of antibody levels in older adults [27] These enhanced responses emphasize the importance of exercise during a global pandemic, as it was already suggested [28], since both a single session of acute exercise or a repetition of the exercise over time boosts the immune system independently of age, physical fitness, or the presence of pathologies [29]. This phenomenon explains both, the benefits that exercise interventions (acute or chronic, with a moderate to high intensity) have in our organism, as well as the negative effects caused by overtraining, like the deregulation of the inflammation processes and a decrease in the ability to maintain homeostasis or homeodynamic regulation [32,33,34]
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