Neutrophils Provide a Favorable IL-1-Mediated Immunometabolic Niche that Primes GLUT4 Translocation and Performance in Skeletal Muscles

Abstract

Summary: Metabolic immunomodulation involving IL-1 has been investigated for unfavorable metabolic effects, including obesity, but a potentially favorable role for IL-1 remains unclear. Here, we find mechanistic interactions between working skeletal muscles and locally recruited neutrophils expressing IL-1β, which supports muscle performance through priming exercise-dependent GLUT4 translocation. Thus, during exercise, both IL-1α/β-deficient and neutrophil-depleted mice similarly exhibit increased fatigability associated with impaired muscle glucose homeostasis due to GLUT4 dysregulation. Deficiency of IL-1-producing neutrophils results in intrinsic abnormalities represented by aberrant Rac1 signaling and irregular GLUT4-storage vesicles, suggesting that these properties are maintained by local IL-1 produced by recruited neutrophils upon exercise, possibly on a daily basis. We propose that neutrophils are highly engaged in skeletal muscle performance via IL-1 regulation, which coordinates favorable inflammatory microenvironments supporting muscle glucose metabolism. : Immunometabolic IL-1 action has been investigated under unfavorable conditions such as obesity and insulin resistance, but potential favorable IL-1 actions remain unknown. Tsuchiya et al. reveal mechanistic interactions during exercise between working skeletal muscles and locally recruited neutrophils expressing IL-1β, which positively supports muscle performance by priming exercise-dependent GLUT4 translocation. Keywords: Exercise, immunometabolism, myokines, metabolism, inflammation, GLUT4, Rac1