title: Shift of homeostasis from parenchymal regeneration to fibroblast proliferation induced by lipopolysaccharide-activated macrophages in gastric mucosal healing in vitro.
abstract: Wound healing in the gastrointestinal tract is an orderly process involving orchestrated responses of various cell types. Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria, which are known to impair gastric ulcer healing in animals. The influence of LPS on intercellular communication in wound healing, however, is unknown. We examined the effects of LPS-induced macrophage activation on the proliferative response in cultured rat gastric epithelial cells (RGM-1) and fibroblasts JHU-25. Rat peritoneal resident macrophages were activated with increasing doses of LPS. The supernatant from the activated macrophage preparation, designated as macrophage-conditioned medium, was then used to treat RGM-1 or JHU-25 cells. Cell proliferation and migration were determined by [(3)H]-thymidine incorporation and a monolayer wound-healing assay, respectively. Macrophage-conditioned medium significantly suppressed RGM-1 cell proliferation but had no effect on cell migration. The same medium, however, increased JHU-25 cell proliferation. LPS treatment alone suppressed JHU-25 cell proliferation while it had no effect on RGM-1 cell proliferation, indicating that the differential effects of the macrophage-conditioned medium on cell proliferation were elicited by the factors derived from macrophages. In this regard, tumor necrosis factor (TNF)-alpha stimulated while interleukin (IL)-1beta suppressed RGM-1 cell proliferation, suggesting that IL-1beta but not TNF-alpha may play a part in the mediation of the antiproliferative effect of macrophage-conditioned medium on gastric epithelial cells. In contrast, IL-1beta suppressed while TNF-alpha had no effect on JHU-25 cell proliferation. Collectively, LPS-activated macrophages delay gastric mucosal regeneration but promote fibroblast proliferation in vitro. Such changes may partly elucidate the detrimental effect of bacterial infection on tissue repair in the stomach.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: William K K
authors.initials: WK
authors.lastname: Wu
authors.forename: William Ka Kei
authors.initials: WK
authors.lastname: Wu
authors.forename: Priscilla T Y
authors.initials: PT
authors.lastname: Law
authors.forename: Priscilla Tak Yin
authors.initials: PT
authors.lastname: Law
authors.forename: Helen P S
authors.initials: HP
authors.lastname: Wong
authors.forename: Helen Pui Shan
authors.initials: HP
authors.lastname: Wong
authors.forename: Emily K Y
authors.initials: EK
authors.lastname: Lam
authors.forename: Emily Kai Yee
authors.initials: EK
authors.lastname: Lam
authors.forename: Emily K K
authors.initials: EK
authors.lastname: Tai
authors.forename: Emily Kin Ki
authors.initials: EK
authors.lastname: Tai
authors.forename: Vivian Y
authors.initials: VY
authors.lastname: Shin
authors.forename: Vivian Yvonne
authors.initials: VY
authors.lastname: Shin
authors.forename: Chi H
authors.initials: CH
authors.lastname: Cho
authors.forename: Chi Hin
authors.initials: CH
authors.lastname: Cho
mesh_terms: D000818:Animals; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D005347:Fibroblasts / Q000502:physiology*; D005753:Gastric Mucosa / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014945:Wound Healing / Q000502:physiology*
chemical_list: D017077:Culture Media, Conditioned; D008070:Lipopolysaccharides