Investigation of effect of lipopolysaccharide on phagocytic activity of collagen fibrils by periodontal fibroblast

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To investigate the effect of lipopolysaccharide on phagocytic activity of collagen fibrils by periodontal fibroblasts, We studied rat molar gingival connective tissue and periodontal ligament under light and electron microscopy after topical application of LPS (5 mg/ml in physiological salt solution, LPS from Escherichia coli from Sigma Chemical Co., St.Louis, MO USA) on the gingival sulcus. Collagen phagocytosis by gingival and periodontal fibroblasts was studied by enzyme histochemistry and morphometric analysis. Phagocytic activity of collagen fibrils by fibroblasts was evaluated by counting the number of collagen-containing vacuoles inside fibroblasts that were present within a defined area (1200mum^2). Values obtained from fibroblasts in the subepithelial connective tissue, the region near the alveolar crest, and the middle region of periodontal tissue were compared. Periodontal ligament fibroblasts showed increased phagocytosis of the collagen fibrils from 3 hours to 1 day after … More topical application of LPS,but, no differences were observed in the gingival tissue. The intracytoplasmic vacuoles containing collagen fibrils were of various sizes and shapes, and showed positive for acid phosphatase and/of alkaline phosphatase reaction. These results indicated that endotoxin may enhance the the degradation of collagen by stimulating the phagocytotic activity of the periodontal ligament fibroblasts. To study the effect of endotoxin on phagocytic activity of collagen fibrils by periodontal fibroblast in vitro system, we obtained 4 fibroblastic spindle-shaped cell lines derived from rat molar periodontal ligaments. These cells were spindle to cuboidal in shape, and showed positivities for alkaline phosphatase reaction and alizarin red S stain for calcium, which are characteristics of periodontal ligament fibroblasts. These cells were cultivated in the collagen gel, but, collagen phagocytosis by these cells were not seen under the ultrastructural observation. We are further studying to get good results, changing a sort of medium, concentrations of collagen gel, methods of observation, etc. Less