Apoptosis in chronic adult periodontitis analyzed by in situ DNA breaks, electron microscopy, and immunohistochemistry

Background: Apoptosis is an evolutionary form of physiological cell death. Previous studies suggest that apoptosis is involved in the pathogenesis of periodontal diseases. Therefore, we studied the apoptotic events in the gin gival tissue of chronic adult periodontitis patients. Methods: Gingival tissue biopsies from 22 patients with chronic adult perio dontitis and from 11 healthy controls were obtained. Criteria for patient i nclusion in the periodontitis group were a minimum of 14 natural teeth, exc luding third molars, with at least 10 posterior teeth; 5 to 6 sites with pr obing depth greater than or equal to5 mm; attachment loss greater than or e qual to3 mm; and extensive radiographic bone loss. The control group includ ed healthy subjects with no prior history of periodontal disease. Apoptosis was determined using the terminal TdT-mediated dUTP-biotin nick end labeli ng (TUNEL) technique; electron microscopic analysis; and expression of Casp ase-3, Fas, Fast, Bcl-2, and p53 by immunohistochemistry. Results: TUNEL-positive cells and cells exhibiting chromatin condensation b y electron microscopy were observed in the inflammatory infiltrate of biops ies obtained from periodontitis patients. Most of the TUNEL-positive cells belonged to neutrophil cell populations as they were stained with anti-myel operoxidase. Positive staining for active-caspase 3, Fas, Fast, and p53 was only observed in the inflammatory infiltrate from periodontitis biopsies, whereas Bcl-2 cells were present in both periodontitis patients and healthy controls. Conclusions: Our findings establish that apoptosis is induced in the period ontal tissue by host and microbial factors and support the hypothesis that apoptotic mechanisms could be implicated in the inflammatory process associ ated with gingival tissue destruction observed in adult periodontitis patie nts.