It is well known that proinflammatory cytokines produced by host cells play an important role in periodontal tissue destruction. However, the localization of the cytokines in in vivo periodontal tissues during development of @entity2520 has not been determined. Immunohistochemical expression of proinflammatory cytokines including @entity8885 , @entity3426 , and @entity1505 was examined at 1 and 3 h, and 1, 2, 3, and 7 days after topical application of lipopolysaccharide (LPS; 5 mg/ml in physiological saline) from @entity526 into the @entity35 molar gingival sulcus. In the normal periodontal tissues, a small number of cytokine-positive epithelial cells were seen in the junctional epithelium (JE), oral sulcular and oral gingival epithelium, in addition to macrophages infiltrating in the subjunctional epithelial area and osteoblasts lining the alveolar bone surface. Epithelial remnants of Malassez existing throughout periodontal ligament were intensely positive for @entity3426 but negative for the other two cytokines. At 3 h after the LPS treatment, almost all cells in the JE were strongly positive for the cytokines examined. In addition, several cytokine-positive cells, including neutrophils, macrophages, and fibroblasts, were seen in the subjunctional epithelial connective tissue. At day 2, expression of the cytokines in the JE gradually decreased, while cytokine-positive cells in the connective tissue increased in number. Positive staining of the cytokines was seen in osteoclasts and preosteoclasts which appeared along the alveolar bone margin in this period. The number of cytokine-positive cells decreased by day 7. These findings indicate that, in addition to macrophages, neutrophils, and fibroblasts, the JE cells are a potent source of @entity1505 , @entity8885 , and @entity3426 reacting to LPS application, and suggest that JE cells may play an important role in the first line of defense against LPS challenge, and the proinflammatory cytokines transiently produced by various host cells may be involved in the initiation of @entity32 and subsequent periodontal tissue destruction.

Cytokine expression in XXXX molar gingival periodontal tissues after topical application of lipopolysaccharide.

@entity32 :: ('MESH:D007249', 'Disease') :: ['inflammation'] @entity2520 :: ('MESH:D010510', 'Disease') :: ['periodontal disease'] @entity1505 :: ('24835(Tax:10116)', 'Gene') :: ['TNF-alpha'] @entity8885 :: ('24493(Tax:10116)', 'Gene') :: ['IL-1alpha'] @entity3426 :: ('24494(Tax:10116)', 'Gene') :: ['IL-1beta'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity526 :: ('562', 'Species') :: ['E. coli']
@entity35 :: (10116,Species) :: ['rat']
