Continuity between wound macrophage and fibroblast phenotype: analysis of wound fibroblast phagocytosis.
Analysis of phagocytic activity in wound fibroblasts was chosen as a means to assess the possible continuity between macrophage and fibroblast phenotypes. Fibroblast phagocytosis of uncoated, IgG-coated, or collagen-coated fluorescent beads was analyzed by flow cytometry in vivo and in vitro. Phagocytosis of fluorescent beads by procollagen I-positive cells (fibroblasts) was evaluated in vivo by injecting beads into subcutaneously implanted sponge wounds in anesthetized Fisher rats. Phagocytic activity of a purified population of wound fibroblasts was measured in vitro and correlated with oxidation state using hydroethidium. In the wound environment, 50-60% of the cells that engulfed uncoated, IgG-coated, or collagen-coated beads were procollagen I-positive cells (i.e., fibroblasts). Procollagen I-positive cells engulfed uncoated and IgG-coated beads in preference to collagen-coated beads in vivo. Cultured wound fibroblasts engulfed uncoated, IgG-coated, and collagen-coated particles. The majority of fibroblasts that engulfed beads were in an elevated oxidation state. We conclude that substantial fibroblast phagocytosis occurs in the wound, but scavenger receptor-mediated fibroblast phagocytosis is different from that of macrophages. Additional markers will be helpful in defining the macrophage fibroblast continuum.
Center for Wound Healing and Reparative Medicine, Department of Surgery, University of Minnesota, Minneapolis, Minnesota 55455, USA.
W J
WJ
Arlein
J D
JD
Shearer
M D
MD
Caldwell
D000818:Animals; D005347:Fibroblasts / Q000473:pathology / Q000502:physiology; D005434:Flow Cytometry; D007074:Immunoglobulin G / Q000032:analysis; D007249:Inflammation; D008264:Macrophages / Q000473:pathology / Q000502:physiology*; D008297:Male; D010587:Phagocytosis / Q000502:physiology*; D011347:Procollagen / Q000096:biosynthesis; D051381:Rats; D011916:Rats, Inbred F344; D014947:Wounds and Injuries / Q000473:pathology / Q000503:physiopathology*
D007074:Immunoglobulin G; D011347:Procollagen