EXERCISE-INDUCED SYSTEMIC ADAPTATIONS: ROLE OF REDOX PERTURBATION IN THE MOLECULAR CROSS-TALK MEDIATED BY EXTRACELLULAR VESICLES (EVs)

Regular physical activity is a potent physiological stimulus that promotes beneficial adaptations across multiple tissues. Central to these effects is the redox signaling, whereby reactive oxygen species (ROS), particularly hydrogen peroxide (H₂O₂), act as tightly regulated second messengers rather than merely harmful metabolic by-products. Within a physiological range, exercise-induced ROS link muscle contraction to the activation of transcriptional programs governing antioxidant defense, mitochondrial biogenesis, metabolic remodeling, and cell survival. Increasing evidence also identifies extracellular vesicles (EVs) as critical mediators of exercise-induced intercellular communication, enabling the transfer of bioactive cargo, such as proteins, lipids, and microRNAs (miRNAs), to coordinate local and systemic adaptations. This PhD thesis investigates the interplay between physical activity, redox signaling, and EV-mediated communication related to systemic adaptations, with a primary focus on skeletal muscle tissue. Through original experimental studies combined with narrative and systematic reviews and meta-analytical approaches, this work examines how controlled exercise-induced redox perturbations regulate EV biogenesis, molecular cargo, and biological function, and how these processes contribute to cellular resilience and whole-body homeostasis. Experimental findings demonstrate that physiologically relevant H₂O₂-mediated redox changes differentially modulate EV biogenesis according to muscle cell differentiation status. Differentiated myotubes respond to controlled oxidative stimuli with enhanced EV release and activation of vesiculation pathways, supporting the concept that mature muscle fibers are a principal source of exercise-induced EVs. In contrast, proliferating myoblasts show display an attenuated EV secretory response due to heightened sensitivity to oxidative stress, prioritizing redox protection and survival over intercellular signaling. Consistently, excessive oxidative stress severely compromises myoblast redox balance, viability, and proliferative capacity; however, treatment with Moringa oleifera leaf extract effectively counteracts these effects by enhancing antioxidant defenses, and preserving regenerative potential, thereby highlighting the relevance of nutritional strategies in supporting redox homeostasis and muscle adaptation. At the systemic level, exercise-induced redox signaling contributes to the regulation of whole-body homeostasis, with ROS exerting a dual and context-dependent role across multiple tissues. While excessive oxidative stress is associated with cellular dysfunction, appropriately dosed physical activity enhances endogenous antioxidant defenses and supports physiological function. This balance is particularly critical in redox-sensitive systems, such as the male reproductive axis, where controlled ROS signaling is required for spermatogenesis, whereas redox imbalance promotes testicular dysfunction and impaired sperm quality. Finally, a systematic review and meta-analysis reveal that EV-derived miRNAs significately reduce intracellular ROS and lipid peroxidation in recipient tissues while increasing antioxidant enzyme activity, identifying EV-associated miRNAs as epigenetic regulators of redox balance that support healthy aging and mitigate the onset and progression of several diseases. Overall, this thesis presents a comprehensive model in which exercise-induced redox signaling links intracellular adaptation to EV-mediated intercellular communication. By showing that ROS modulate EV biogenesis and cargo composition, this work identifies EVs as central conveyors of redox information from muscle and other organs to distant tissues. Notably, the redox sensitivity of EV content highlights their potential as accessible biomarkers of oxidative stress–related conditions, supporting the development of personalized, exercise-based strategies aimed at preserving and promoting human health and well-being.