Fibroblast growth in vitro suppressed by LPS-activated macrophages. Reversal of suppression by hydrocortisone.
Activated macrophages are among the major constituents of the periapical granuloma. Their state of activation may persist for long periods after the local irritant is removed and may delay resolution and repair of the lesion. The effect of activated macrophages on fibroblast growth was studied in vitro. Circular fibroblast colonies were formed using a drop containing 7.5 x 10(5) murine dermal fibroblasts and allowed to grow for 7 days. When peritoneal exudate macrophages were added (0.5-3.0 x 10(6) cells/dish) and activated in vitro by LPS (1 microgram/ml), the fibroblast colony's growth was suppressed. LPS alone, at the concentration used, had no effect on the fibroblast growth. Hydrocortisone (> or = 10(-7) M) totally reversed the suppression, when added either simultaneously with or 6, 24, or 48 h after the LPS. The efficacy of late hydrocortisone treatment suggests that its effect was through prevention of the expression of the LPS activation of the macrophages. These findings may provide a possible clue to a pharmacological modulation of the healing processes that occur in the periapical lesion once its infective source had been eliminated.
Metzger
Z
Z
Department of Oral Biology,School of Dental Medicine, Tel Aviv University, Israel.
Berg
D
D
Dotan
M
M
D000818:Animals; D000831:Animals, Newborn; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D004926:Escherichia coli; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006854:Hydrocortisone / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects*; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D012867:Skin / Q000166:cytology* / Q000187:drug effects; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D003470:Culture Media; D008070:Lipopolysaccharides; D006854:Hydrocortisone