The Role of Interleukin-10 in Mitigating Endoplasmic Reticulum Stress in Aged Mice Through Exercise

While unfolded protein response (UPR) is essential for cellular protection, its prolonged activation may induce apoptosis, compromising cellular longevity. The aging process increases the endoplasmic reticulum (ER) stress in skeletal muscle. However, whether combined exercise can prevent age-induced ER stress in skeletal muscle remains unknown. Evidence suggests that ER stress may increase inflammation by counteracting the positive effects of interleukin-10 (IL-10), while its administration in cells inhibits ER stress and apoptosis. This study verified the effects of aging and combined exercise on physical performance, ER stress markers, and inflammation in the quadriceps of mice. Moreover, we verified the effects of IL-10 on ER stress markers. C57BL/6 mice were distributed into young (Y, 6-month-old), old sedentary (OS, sedentary, 24-month-old), and old trained group (OT, submitted to short-term combined exercise, 24-month-old). To clarify the role of IL-10 in UPR pathways, knockout mice lacking IL-10 were used. The OS mice presented worse physical performance and higher ER stress-related proteins, such as CHOP and p-eIF2α/eIF2α. The exercise protocol increased muscle strength and IL-10 protein levels in OT while inducing the downregulation of CHOP protein levels compared to OS. Furthermore, mice lacking IL-10 increased BiP, CHOP, and p-eIF2α/eIF2α protein levels, indicating this cytokine can regulate the ER stress response in skeletal muscle. Bioinformatics analysis showed that endurance and resistance training downregulated DDIT3 and XBP1 gene expression in the vastus lateralis of older people, reinforcing our findings. Thus, combined exercise is a potential therapeutic intervention for promoting adjustments in ER stress markers in aged skeletal muscle.