AGEs impair skeletal muscle regeneration through their effects by macrophage activity

Advanced glycation end products (AGEs), formed by the non-enzymatic reaction between sugars and proteins, contribute to the development of various diseases, including neurodegenerative diseases, diabetes, and sarcopenia. This study investigated the effects of AGEs on skeletal muscle regeneration. Eight-week-old male C57Bl/6NCr mice were divided into an AGEs-treated group and a control group administered bovine serum albumin (BSA). One week after intraperitoneal injection of AGEs (0.5 mg/g body weight) or BSA, cardiotoxin (10 μM, 100 μL) was injected into the tibialis anterior (TA) muscle of the hind limbs to induce injury. Muscle samples were collected on days 3, 7, and 14 post-injury and analyzed using HE staining, immunohistochemistry, and real-time qPCR. There were no significant differences in body weight or food consumption between the AGEs and BSA groups at any time point. On day 3, the relative muscle weight to body weight ratio was significantly lower (p = 0.0017) in the AGEs group. On day 7, the AGEs group displayed a significantly lower number of centrally nucleated myofibers (p < 0.001) compared to the BSA group. Sirius Red staining revealed no significant differences between groups at any time point. On day 3, the expression levels of regeneration markers Myozenin-1 (p = 0.0425) and Dystrophin (p = 0.0935) were lower in the AGEs group, although Troponin I2 showed no significant difference. On day 14, macrophage markers F4/80 (p < 0.001), Cd68 (p = 0.0061), and pro-inflammatory macrophage markers Cd86 (p = 0.0058) were significantly higher in the AGEs group, while anti-inflammatory marker Cd206 remained unchanged. Similarly, the macrophage-inducing factor Ccl2 was significantly higher in the AGEs group on day 14 (p = 0.0447). Additionally, Fndc5, which inhibits polarization toward a pro-inflammatory macrophage state, was significantly higher in the AGEs group on day 3 (p = 0.0065). These findings indicate that AGEs delay skeletal muscle regeneration, as evidenced by a lower relative muscle weight to body weight ratio, a lower number of centrally nucleated myofibers, and decreased expression of Myozenin-1 and Dystrophin. On day 14, the high expression of C cl 2 and C d 86 suggests that AGEs may sustain inflammation during muscle regeneration by promoting prolonged expression of pro-inflammatory macrophages, potentially impairing the regeneration process. Furthermore, higher Fndc5 on day 3 may modify the early inflammatory response, thereby disrupting initial muscle regeneration. These results suggest that AGEs may impede skeletal muscle repair by modulating macrophage response. Supported by JSPS KAKENHI project number 23K21598, 22K18413 and 23K27973. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.