title: Macrophages, not neutrophils, infiltrate skeletal muscle in mice deficient in P/E selectins after mechanical reloading.
abstract: Our objective was to test the hypothesis that endothelial selectins, P and E selectins, are necessary for leukocyte migration after muscle injury from unloading/reloading. Mice hindlimbs were suspended for 10 days followed by reloading periods of 6 or 24 h after which the soleus muscle was dissected. Light microscopic observations showed that macrophages, but not neutrophils, were able to invade soleus muscles in mice deficient in P/E selectins (P/E-/-) during reloading periods. The recruitment efficiency of neutrophils after 6 and 24 h of reloading was minimal in P/E-/- mice relative to unloaded animals. The recruitment of macrophages in the soleus muscle was preserved in P/E-/- mice. The concentration of macrophages increased by 8.1-fold compared with unloaded muscles in double-mutant mice after 24 h of reloading. The accumulation of macrophages in reloaded muscles did not lead to fiber necrosis. Together, these findings indicate that macrophages can invade skeletal muscle through cellular mechanisms that do not involve P/E selectins during skeletal muscle reloading.
authors.affiliation: Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec, Canada. jerome.frenette@crchul.ulaval.ca
authors.forename: Jĕrôme
authors.initials: J
authors.lastname: Frenette
authors.forename: Nadia
authors.initials: N
authors.lastname: Chbinou
authors.forename: Charles
authors.initials: C
authors.lastname: Godbout
authors.forename: David
authors.initials: D
authors.lastname: Marsolais
authors.forename: Paul S
authors.initials: PS
authors.lastname: Frenette
mesh_terms: D000818:Animals; D019040:E-Selectin / Q000235:genetics*; D019417:Hindlimb Suspension / Q000502:physiology*; D007958:Leukocyte Count; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology*; D009220:Myositis / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D009504:Neutrophils / Q000166:cytology*; D019007:P-Selectin / Q000235:genetics*; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D019040:E-Selectin; D019007:P-Selectin