Upon injury, inflammatory cells are recruited to the injury site, attracted by chemokines and  cytokines, releasing from dead or dying cells. Innate immune cells consists predominantly macrophages and neutrophils, migrating acoss the vascular wall, interstitium and other barriers to the occurance. In addition, resident cells and intrinsic leukocytes undergo significant activating and praliferaton to promoter tissue repair. Macrophages are involed in all stages of tissue repair.                     Resident macrophages are under steady-state conditions, while monocyte-derived macrophages 

are recruited from the bone marrow after injury. Macrophage are extramely heterogenious.  Resident macrophages labe macrophage colony-stimuating factor 1 receptor(CSF1R/M-CSF). Liver macrophage populations are Kupper cells, lung macrophage populations are alveolar and nervous system macrophage populations are microglia. 

     Blood monocyte cells express the chemokine factor-CCR2, responding to CCL2 and producting high level TNFalpha and MHCII. 

References

1、Macrophages,Wound healing, and Fibrosis:Recent Insights