EPIDERMAL GROWTH-FACTOR IN GINGIVAL CREVICULAR FLUID AND ITS BINDING-CAPACITY IN INFLAMED AND NONINFLAMED HUMAN GINGIVA

Epidermal growth factor (EGF) is a pro-inflammatory small peptide (600 0 Da),with a variety of biological activities including stimulation of cell differentiation and mediation of proteolysis by binding to its s pecific receptor on the cell surface. The purpose of this study was to determine the levels of EGF in gingival crevicular fluid (GCF) and th e EGF-binding capacity to its receptor in gingival tissue. The GCF sam ples were collected from six patients by inserting paper strips into s hallow (< 5 mm) and deep pockets (greater than or equal to 5 mm) for 3 0 s. The strips were soaked in 0.2 M acetate for extraction and the EG F in the supernatants was analysed by radioimmunoassay. To determine t he binding capacity of EGF to its receptor, inflamed gingival tissues (pocket depth greater than or equal to 5 mm, Gingival Index = 1, 2 or 3) were collected during periodontal flap surgery and non-inflamed gin gival tissues (pocket depth < 5 mm, Gingival Index = 0) were collected during surgical 'crown lengthening' for aesthetic purposes. The tissu es were pooled by group, homogenized for membrane preparation and the supernatants obtained after centrifugation were used in a (125)IEGF bi nding assay. To determine the effect of inflammation on gingival EGF r eceptor, inflamed and non-inflamed gingival tissues were collected fro m six patients and prepared similarly to the binding assay. Gingival p reparations were then electrophoresed for Western blot analysis with E GF receptor antiserum. The EGF level in GCF was significantly lower (P < 0.05) in the samples collected from pockets greater than or equal t o 5 mm (0.9+/-0.6 ng/ml) than in those from pockets < 5 mm (2.4+/-2.1 ng/ml). The average Gingival Index was higher (2.6+/-0.6) in pockets g reater than or equal to 5 mm than in pockets < 5 mm (1.4+/-1.0). Speci fic binding of I-125-EGF to its receptor in inflamed gingiva was 2.7-f old higher than in non-inflamed gingiva (14.4+/-4.9 vs 5.4+/-1.8 fmol/ g wet tissue). Western blot analysis showed two major immunoreactive b ands (180 and 120 kDa), which represent EGF receptor and its degradati on products, in inflamed gingiva. The findings show that inflammation activates EGF binding capacity in gingiva and that the up-regulation o f EGF receptor in inflamed gingiva might be associated with a lowered concentration of EGF in GCF produced adjacent to inflamed gingiva. Thi s up-regulation of EGF receptor during inflammation might be an import ant mechanism in the pathogenesis of periodontal disease. Copyright (C ) 1996 Published by Elsevier Science Ltd.