Moderate Exercise Training Improves Several SCD Features in Experimental Mice Models, Study Shows

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by Alice Melão |

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Moderate exercise training can improve many features of sickle cell disease (SCD) in experimental mice models, including inflammation, lack of oxygen in the blood and spleen enlargement, according to a French study.

The report, “Moderate exercise training decreases inflammation in transgenic sickle cell mice,” appeared in the scientific journal Blood Cells, Molecules and Diseases.

Due to a genetic alteration, SCD patients produce an abnormal form of hemoglobin, called hemoglobin S or HbS. The presence of this HbS triggers a cascade of events which ultimately induces persistent inflammation, with consequent severe tissue damage and even death.

Among healthy individuals, physical exercise can induce the temporary production of inflammatory molecules and oxidative stress. Because of the increased risk of causing a painful vasoocclusive crisis, SCD patients are normally advised to not engage in aggressive sporting activities. However, some studies have suggested that exercise can actually improve these features among SCD patients.

To test their hypothesis that regular physical training could improve the inflammatory status in SCD, researchers subjected animal models genetically manipulated to only express human sickle hemoglobin to an eight-week program of moderate exercise training.

They found evidence suggesting that physical training could limit blood deoxygenation, or lack of oxygen in the blood, in resting state, reduce systemic and organ inflammation, and attenuate spleen enlargement. Overall, the training exercise imposed on these mice was found to be well tolerated, and induced a normal physiological response without affecting red blood cell counts or hemoglobin levels.

Interestingly, researchers observed that mice which underwent regular training sessions showed improved blood oxygenation while resting. This effect could be due to better muscle metabolism induced by frequent exercise, which would interfere with abnormal hemoglobin polymerization and limit the sickling of red blood cells, authors explained.

In addition, they found that physical training reduced carboxyhemoglobin levels. Previous studies have showed that carboxyhemoglobin is a reliable marker of hemolysis, or rupture of red blood cells. Given that, the observed reduction in SCD mice suggests that exercise could attenuate hemolysis. However, more studies focused on hemolysis biomarkers may confirm this hypothesis.

Systemic inflammation, measured by levels of white blood cells in circulation and inflammatory biomarkers blood levels, was lower in animals that underwent a moderate exercise plan. Also, the mice had smaller spleens and better spleen structure, which could reduce the risk of spleen-associated complications.

“Our data provide evidence to support the notion that moderate aerobic exercise may result in systemic as well as tissue specific improvements in pathways known to adversely affect patients with SCD,” the authors wrote. “These findings strengthen the previous evidence that exercise training, with appropriate safety considerations, could serve as a potential therapeutic option for a large number of patients worldwide.”