MCP-1 parallels inflammatory and regenerative responses in ischemic muscle.
BACKGROUND
Monocyte chemotactic protein-1 (MCP-1) is important in macrophage recruitment and activation. However, the magnitude and temporal sequence of MCP-1 expression in relation to tissue injury and regeneration following ischemic injury remains unknown.


METHODS
Hind limb ischemia was induced by femoral artery excision (FAE) in C57Bl/6J mice; a sham surgery was performed on the contralateral leg. Muscle lysates were used to measure MCP-1 and activities of creatine kinase, lactate dehydrogenase, and myeloperoxidase. Histology and immunohistochemistry were used to localize inflammation and MCP-1.


RESULTS
FAE resulted in a prolonged period of ischemia and the administration of MCP-1 did not alter the restoration of perfusion. One day after femoral artery excision, extensive muscle necrosis and neutrophils were prevalent throughout the musculature of the lower leg. By 3 days, a mononuclear cell infiltrate predominated in association with robust muscle regeneration as indicated by myoD expression. Concomitantly, myeloperoxidase was maximally increased. Muscle enzymes (creatine kinase and lactate dehydrogenase) were maximally decreased within 3 days and returned to baseline levels by day 14, a time course consistent with injury and regeneration observed by histology. In parallel with these inflammatory and regenerative events, MCP-1 in muscle was maximally increased at day 3. By immunohistochemistry, MCP-1 was within vascular endothelial cells and infiltrating macrophages in areas of ischemic injury.


CONCLUSIONS
The transient increases and selective tissue distribution of MCP-1 during early inflammation and muscle regeneration support the hypothesis that this cytokine participates in the early reparative events preceding the restoration of vascular perfusion following ischemic injury.
South Texas Veterans Health Care System, San Antonio, TX 78229-3900, USA. shireman@uthscsa.edu
Paula K
PK
Shireman
Veronica
V
Contreras-Shannon
Sara M
SM
Reyes-Reyna
Susan C
SC
Robinson
Linda M
LM
McManus
D000818:Animals; D018932:Chemokine CCL2 / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D003402:Creatine Kinase / Q000378:metabolism; D007249:Inflammation / Q000209:etiology*; D007511:Ischemia / Q000503:physiopathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology*; D009929:Organ Size; D009195:Peroxidase / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000502:physiology; D012038:Regeneration
C515335:Ccr2 protein, mouse; D018932:Chemokine CCL2; D012333:RNA, Messenger; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D007770:L-Lactate Dehydrogenase; D009195:Peroxidase; D003402:Creatine Kinase