Strength and Aerobic Physical Exercises Are Able to Increase Survival of Toxoplasma gondii-Infected C57BL/6 Mice by Interfering in the IFN-γ Expression

Abstract

Physical exercise has been implicated in several immunophysiological improvements, particularly during the aging process, when an immunocompromised status could be established. Toxoplasma gondii is a protozoan parasite that causes a widespread opportunistic infection, which may present severe consequences, mainly to the fetus and immunocompromised patients. It is estimated that one-third of the human population worldwide has been infected by this parasite, being the reactivation during immunesenescence an unexplored public health issue. The major purpose of the present study was to observe the immunophysiological differences between exercised vs. sedentary C57BL/6 male mice that have been experimentally infected by T. gondii. In the first set of experiments, the animals were infected after exercising and three groups were set up: experimental groups—infected sedentary (IS, n = 6); infected exercised (IEx, n = 6) and control group—non-infected sedentary (NIS, n = 6). When stimulated in vitro by T. gondii-soluble tachyzoite antigen, it was found that splenocytes from exercised group produced higher levels of IFN-γ, as well as of IFN-γ/IL-10 ratios in comparison with splenocytes from sedentary animals (P < 0.001). However, it was not found significant differences concerning quantification of T. gondii genomic DNA by qRT-PCR and immunohistochemistry analysis in brain cysts from both group of animals (P > 0.05). In order to further investigate the consequences of these data for the host, a second set of experiments was performed, when the animals were infected before exercising and four groups of animals were established for comparison purpose, as follows: experimental groups—infected sedentary (IS, n = 7); infected exercised (IEx, n = 6) and control groups—non-infected sedentary (NIS, n = 6) and non-infected exercised (NIEx, n = 6). It was found significant differences in the survival rates of the exercised group the animals, as they survived longer than sedentary groups (P = 0.0005). In both sets of experiments, mice have been submitted to moderate exercises: aerobic (14 m/min; 3 x/week) and strength (60–80% of one maximum repetition; 2 x/week). Overall, our findings are showing that the aerobic and strength exercises are able to modulate immune response against T. gondii infection, being these immunological features beneficial to the host.

Resistance Training Improves the Immune Response, Mainly Associated with CD8+ T Lymphocytes and B Lymphocytes, in Mice

“…Physical exercise has been identified as a protective factor for health and well-being by increasing the immunological response [2], due to its anti-inflammatory activity [3,4]. Physical exercise of moderate intensity [5] induces a discharge of catecholamines (adrenaline and norepinephrine), leading to an increase in the concentration of T lymphocytes in the vascular compartment [6].…”

Why Physical Activity Should Be Considered in Clinical Trials for COVID-19 Vaccines: A Focus on Risk Groups

“…Advances in the research on molecular and physiological responses to exercise have given prominence to the field of exercise immunology. In this sense, it is known that physical activity contributes significantly to stimulating crucial components of the immune system [20,21], promoting the host's defense against parasites [22][23][24], treating cancer [25], and regulating autoimmune and hypersensitivity components [26][27][28]. It has also been reported that physical exercise is essential for vaccine effectiveness [29][30][31][32], which is crucial for the new COVID-19 vaccines.…”