Mechanism of endotoxin inhibition of human gingival fibroblast attachment to type I collagen.
Bacterial endotoxin inhibits the attachment of human gingival fibroblasts to collagen. The present study attempted to elucidate the possible mechanism of this inhibition. Two mechanisms were considered: direct toxicity to the cells and steric interference. Collagen substrates were prepared by rat type I collagen being air-dried in the wells of 24 multi-well plates. Experimental collagen substrates were treated with 50 micrograms of endotoxin/well, while untreated collagen substrates served as controls. Two mL of cell suspension (10(4) cells/mL) was added to each well, and these were incubated at 37 degrees C for two h. The average cell number/mm2 attached to experimental and control substrates was determined. Cell attachment to endotoxin-treated collagen was inhibited by 78%, compared with that to untreated collagen. The washing of the endotoxin-treated collagen for two h did not affect the inhibition of cell attachment, whereas after 24 h of washing, cell attachment was inhibited by 54%, compared with that to untreated collagen. Pre-incubation of the cells in endotoxin for two h did not affect their attachment to collagen. The addition of fetal calf serum (15%) to the experimental system completely reversed the inhibition of fibroblast attachment to endotoxin-treated collagen. These findings suggest that endotoxin interferes with fibroblast attachment to collagen through a steric phenomenon, possibly by blocking the binding sites on the collagen molecule recognized by the membrane receptor for collagen.
Pitaru
S
S
Department of Oral Biology, Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel.
Madgar
D
D
Metzger
Z
Z
Hekmati
H
H
D000704:Analysis of Variance; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D003094:Collagen / Q000502:physiology*; D004731:Endotoxins / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects*; D005881:Gingiva / Q000166:cytology; D006801:Humans; D008562:Membrane Glycoproteins / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000187:drug effects; D038981:Receptors, Collagen
D002352:Carrier Proteins; D004731:Endotoxins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D038981:Receptors, Collagen; D003094:Collagen