Impaired function of postoperative macrophages from zinc-deficient rats decreases collagen contraction

Zinc deficiency impairs connective tissue contraction in the perforated rat mesentery model. Since the rat mesentery is almost avascular, free peritoneal macrophages are important for mesenteric repair. Impairment of contraction may thus be caused either by a direct effect of zinc deficiency on tissue cells or by hampered macrophage function. To further elucidate the role of macrophages in tissue contraction, we studied their effect on lattice contraction. A number of typical functions of macrophages in zinc deficiency were also investigated. Lattice contraction was significantly impaired by conditioned medium from zinc-deficient macrophages. Zinc deficiency did not influence peripheral blood leukocyte number, but postoperatively the number of peritoneal macrophages increased on days 7 and 10. A significant release of lysosomal enzymes from macrophages was recorded during phagocytosis, whilst no difference was observed between controls and zinc-deficient macrophages. Superoxide anion generation during phagocytosis was not significantly increased in zinc deficiency. Conditioned medium from zinc-deficient macrophages was shown to impair lattice contraction in vitro and the results are compatible with impaired macrophage function as a cause of decreased connective tissue contraction in vivo.