Immunoexpression of CXC-chemokine and recruitment of polymorphonuclear leukocytes in the rat molar periodontal tissue after topical application of lipopolysaccharide

Accumulating evidence indicates that an important event in the tissue response in periodontal disease is the recruitment of polymorphonuclear leukocytes (PMN). This study investigated immunohistochemical expression of CXC-chemokines, including macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant-2 (CINC-2) in rat periodontal tissue at 1 and 3 hours and 1, 2, 3 and 7 days after topical application of lipopolysaccharide (LPS; 5 mg/ml in saline) from E. Coli into the rat molar gingival sulcus. In normal periodontal tissues before LPS application, a small number of MIP-2 and CINC-2 positive cells were seen in junctional epithelium (JE) especially in its coronal half. After topical application of LPS, a prominent increase of MIP-2 and CINC-2 positive JE cells was observed. Almost all JE cells strongly expressed them at day 1 and day 2, and then the number of chemokine-positive cells returned to normal at day 7. Corresponding to these chemokine expressions, LPS application induced a significant increase in number of PMNs in sub-JE area at 1 hour (P <0.01) and 3 hours (P <0.05) and a significant increase in JE area at 1 day(P< 0.05) and 2 days (P