title: Time course of chemokine expression and leukocyte infiltration after acute skeletal muscle injury in mice.
abstract: Innate pro-inflammatory processes, such as chemokine signaling and leukocyte infiltration, predominate during the first 48 h after an acute skeletal muscle injury. However, the time course of chemokine expression and its relationship to leukocyte infiltration after acute muscle injury within this early post-injury time period has not been investigated. In this study, 46 anesthetized female C57BL/6NHsd mice underwent a closed crush injury of the gastrocnemius muscle and were euthanized 4, 8, 24 and 48 h post-injury. Microarray analysis found 14 chemokine genes to be up-regulated during this period, 12 of which are involved in macrophage or neutrophil chemotaxis, with up-regulation peaking at either 8 or 48 h. RT-PCR analysis on select chemokines confirmed the microarray activation pattern. Neutrophil infiltration patterns mirrored the time course of neutrophil-related chemokines with Gr-1-, 1A8- and 7/4-positive neutrophils infiltrating the muscle 4 h after injury, decreasing at 48 h. Conversely, gene expression and relative quantification levels of macrophage-related chemokines Ccl2 and Ccl7 peaked at 8 h, preceding the infiltration of CD68- and F4/80-positive macrophages, and protein expression of Ccl2 in the muscle. The up-regulation of other macrophage-related chemokines and their receptors peaked at 48 h post-injury.
authors.affiliation: School of Nursing, University of Nevada, Las Vegas, Las Vegas, NV, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nicholas
authors.affiliation: School of Nursing, University of Washington, Seattle, WA, USA.
authors.forename: Joachim G
authors.initials: JG
authors.lastname: Voss
authors.affiliation: School of Nursing, University of Washington, Seattle, WA, USA.
authors.forename: Joyce
authors.initials: J
authors.lastname: Tsuji
authors.affiliation: School of Nursing, University of Nevada, Las Vegas, Las Vegas, NV, USA.
authors.forename: Nadia D
authors.initials: ND
authors.lastname: Fulkerson
authors.affiliation: Department of Statistics, University of Nebraska - Lincoln, Lincoln, NE, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Soulakova
authors.affiliation: School of Nursing, University of Nevada, Las Vegas, Las Vegas, NV, USA Barbara.stpierreschneider@unlv.edu.
authors.forename: Barbara St Pierre
authors.initials: BS
authors.lastname: Schneider
mesh_terms: D000208:Acute Disease; D000818:Animals; D002465:Cell Movement; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D054410:Chemokine CCL7 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D007113:Immunity, Innate; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D046228:Microarray Analysis; D018482:Muscle, Skeletal / Q000276:immunology* / Q000293:injuries; D009504:Neutrophils / Q000276:immunology*; D015854:Up-Regulation
chemical_list: D018932:Chemokine CCL2; D054410:Chemokine CCL7
keywords: Inflammation; macrophage; microarray; muscle recovery; neutrophil