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.
Arlein
W J
WJ
Center for Wound Healing and Reparative Medicine, Department of Surgery, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Shearer
J D
JD
Caldwell
M D
MD
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