title: Preliminary time-course study of antiinflammatory macrophage infiltration in crush-injured skeletal muscle.
abstract: Muscle damage induces massive macrophage infiltration of the injury site, in which activated pro-inflammatory and anti-inflammatory phenotypes (currently classified as M1 and M2, respectively) have been documented as distinct functional populations predominant at different times after the conventional acute injury by intramuscular injection of snake venoms (cardiotoxin, notexin) or chemicals (bupivacaine hydrochloride, barium chloride). The present study employed a muscle-crush injury model that may better reflect the physiologic damage and repair processes initiated by contusing a gastrocnemius muscle in the lower hind-limb of adult mice with hemostat forceps, and examined the time-course invasion of M1 and M2 macrophages during muscle regeneration by immunocytochemistry of CD197 and CD206 marker proteins. CD197-positive M1 macrophages were observed exclusively at 1-4 days after crush followed by the alternative prevalence of CD206-positive M2 at 7 days of myogenic differentiation, characterized by increasing levels of myogenin messenger RNA expression. Preliminary PCR analysis showed that M2 may produce hepatocyte growth factor (HGF) in culture, providing additional benefit to understanding that M2 populations actively promote regenerative myogenesis (muscle fiber repair) and moto-neuritogenesis (re-attachment of motoneuron terminals onto damaged fibers) through their time-specific infiltration and release of growth factor at the injury site early in muscle regeneration.
authors: Department of Animal and Marine Bioresource Sciences, Kyushu University, Fukuoka, Japan.
authors: Jun-ichi
authors: J
authors: Shono
authors: Shohei
authors: S
authors: Sakaguchi
authors: Takahiro
authors: T
authors: Suzuki
authors: Mai-Khoi Q
authors: MK
authors: Do
authors: Wataru
authors: W
authors: Mizunoya
authors: Mako
authors: M
authors: Nakamura
authors: Yusuke
authors: Y
authors: Sato
authors: Mitsuhiro
authors: M
authors: Furuse
authors: Koji
authors: K
authors: Yamada
authors: Yoshihide
authors: Y
authors: Ikeuchi
authors: Ryuichi
authors: R
authors: Tatsumi
mesh_terms: D000818:Animals; D017228:Hepatocyte Growth Factor / Q000096:biosynthesis; D007150:Immunohistochemistry; D008264:Macrophages / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D024510:Muscle Development / Q000502:physiology; D018482:Muscle, Skeletal / Q000293:injuries*; D055495:Neurogenesis / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D013997:Time Factors; D014688:Venoms / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D014688:Venoms; D017228:Hepatocyte Growth Factor
keywords: antiinflammatory macrophage (M2); hepatocyte growth factor (HGF); motoneuritogenesis; muscle crush injury; regeneration