It is known that the prognosis in cancer patients who exercise is better than the ones who are inactive. However, the underlying principle has remained unexplained so far. Now, a study by researchers from at Karolinska Institutet has found that the metabolism of certain immune cells is altered due to exercise, which in turn boosts their ability to seek out and attack cancer cells.
According to the authors, the metabolism of cytotoxic T-cells—white blood corpuscles specialized at killing cancer cells—is greatly improved through physical activity, thus, improving their capacity to destroy cancer cells. "Our research shows that exercise affects the production of several molecules and metabolites that activate cancer-fighting immune cells and thereby inhibit cancer growth," said Helene Rundqvist, first author of the study, in a statement.
Studying the Role of Exercise
Physical exercise has been proven to improve the outcomes in patients struggling with numerous diseases, including several forms of cancer. One prevalent theory is that exercise triggers the immune system into action and strengthens the body's ability to prevent and restrict the growth of cancer. The research team explored this hypothesis by investigating how cytotoxic T-cells respond to physical exercise.
For the study, the authors used two groups of mice. One group of mice was allowed to exercise regularly using a spinning wheel while the other did not engage in any exercise. The researchers discovered that the growth of cancer and mortality was lower in the first group (trained) in comparison to the second (untrained). Following this, the team analyzed the significance of cytotoxic T-cells. For this, they injected antibodies that are meant for the removal of the T-cells in both the untrained and trained mice.
These antibodies undid the positive effects that exercise had on the growth of cancer and the chances of survival. This, according to the authors, was proof of how important cytotoxic T-cells were for the exercise-induced inhibition of cancer. Also, these T-cells were transferred from trained mice to untrained ones with tumors. This improved their prognosis in comparison to those who received t-cells from untrained mice.
Effective Inhibition of Cancer Growth
Next, the scientists sought to understand the influence of exercise on cancer growth. Therefore, they isolated blood, T-cells and tissue samples following trained sessions. The levels of common metabolites that are produced within muscles and are dumped into the plasma in elevated levels during physical exertion, was measured. Certain metabolites, such as lactate, were found to alter the metabolism of T-cells and led to an increase in their activity.
Additionally, it was also learnt that T-cells isolated from animals that exercised, exhibited modified metabolism when compared to T-cells from inactive animals. The researchers also investigated the manner in which these metabolites altered when humans exercised. They obtained blood samples from eight healthy male volunteers after 30 minutes of intense exercise. To the researchers' surprise, the same training-induced metabolites were releases in human beings as well.
Randall Johnson, corresponding author of the study, averred that the biological underpinnings of the positive effects of physical exercise can offer new awareness about how the body sustains health, and can also enable the designing and improvement of cancer therapies. "We hope these results may contribute to a deeper understanding of how our lifestyle impacts our immune system and inform the development of new immunotherapies against cancer," concluded Rundqvist.
