Differential Expression of Gingival Apoptosis Markers in Aged Patients

Objectives:  Periodontal disease is perhaps the most common chronic disorder of infectious origin in humans. Several epidemiological studies have found that the prevalence and severity of periodontal disease increases in elderly patients. Recent studies demonstrated apoptotic events in gingival tissues of patients with chronic periodontitis. The main objective of the current study was to test the hypothesis that periodontal disease activates apoptotic markers in the gingival tissue of older patients.

Methods:  The subjects (18-70 years, N = 20) were enrolled in the clinics of Baylor College of Dentistry and Louisiana State University Dental School following IRB approval into two main groups: healthy (N=8) and periodontitis patients (N=12).  Gingival tissue was collected from sites undergoing periodontal surgical procedures. Gingival tissue was considered diseased when there was bleeding on probing and probing depth >5 mm. The tissue sections were homogenized and subjected to immunoblot analysis for the expression of TNF-alpha receptor death domain (TRADD), cytochrome C, Bax, and caspase-3 known protein markers for endogenous apoptotic processes.  The expression of individual proteins was correlated with the age of the patients in healthy, diseased and cumulative subject groups.

Results:  Diseased subjects exhibited a stronger correlation with the expression of TRADD, Bax and Cytochrome C with age compared to healthy subjects.   On the other hand expression of caspase-3 correlated with an increase in the age of the patient, irrespective of their disease status.

Table: Co-efficient of correlation (r²) between apoptotic markers and age in various groups

Apoptosis markers                Healthy          Diseased         Cumulative

TRADD                                     -0.27                0.65                 -0.21

Bax                                          0.17                 0.75                 0.13

Cytochrome C                         -0.56                0.35                 0.12

Caspase-3                                0.88                 0.21                 0.63

Conclusion:  The data suggest that modulation of both extrinsic and intrinsic apoptotic cascades may contribute to the damage of gingival tissues in older periodontal disease patients.