Exercise alleviates cognitive dysfunction in Alzheimer's disease mice via skeletal muscle-derived extracellular vesicles which enhance plaque clearance by microglia [miRNA-Seq]

Exercise confers cognitive benefits in Alzheimer's disease (AD), yet the underlying mechanisms remain incompletely understood. The skeletal muscle functions as an endocrine organ that secretes myokines which affect the homeostasis of extra-muscular organs, including the brain. Here, we found that swimming exercises promoted the secretion of skeletal muscle-derived extracellular vesicles (SKM-EVs), which subsequently pinocytosis by microglia. Gain- and loss-of-function experiments showed that exercised SKM-EVs activated the polarization of disease-associated microglia (DAM) and enhanced the clearance of amyloid-beta (Aß) plaques. Furthermore, miR-378a-3p was identified as the key miRNA in SKM-EVs and promoted lipid metabolism in DAM by targeting p110a. Importantly, the therapeutic administration of EVs derived from mir-378a overexpressing myotubes alleviated cognitive impairment in AD mice. Together, our findings demonstrate that exercised SKM-EVs could serve as a novel myokine mediating communication from skeletal muscle to the brain and develop alternative therapeutic strategies for exercise in AD treatment. Overall design: In order to further understand the potential mechanism of SKM-EVs involved in delaying cognitive function in AD mice during exercise, especially the biological role of their contents. We constructed a skeletal muscle ex vivo exercise model using the Aurora Scientific 2000A skeletal muscle isolation system, simulated exercise (EX) and sedentary (ST) states through pulsed electrical stimulation, and collected their SKM-EVs for microRNA sequencing analysis.