Abstract

VERNAL, R.; DUTZAN, N.; LEON, R.  and  GAMONAL, J.. Role of CD4⁺ T cells in bone destruction during chronic periodontitis. Avances en Periodoncia [online]. 2006, vol.18, n.3, pp.149-162. ISSN 2340-3209.

Background: Chronic periodontitis is an infectious disease, characterized by alveolar bone destruction and teeth loss. Receptor activator of nuclear factor kB- ligand (RANKL) is an osteoclastogenic cytokine, central regulatory factor in the osteoclasts life-span and physiological and pathological bone resorption. Gingival T cells synthesize RANKL contributing to molecular local unbalance that entail to the alveolar bone resorption seen in periodontitis. Our study was aimed at associating the levels of RANKL with the CD4+ T cell activity present in gingival tissues of chronic periodontitis patients. Methods: Gingival biopsies were obtained from 33 chronic periodontitis patients and 20 healthy controls. Specimens were either formalin fixed and paraffin embedded for real-time reverse transcriptionpolymerase chain reaction (RT-PCR) and histological analysis, or tissue digestion processed for cell culture and flow cytometry analysis. RANKL mRNA and protein levels were determined by quantitative RT-PCR and enzyme-linked immunosorbent assay (ELISA) in gingival cells culture supernatants. Gingival leukocytes were quantified by flow cytometry. RANKL and CD4 immunoreactivity was analyzed by flow cytometry and confocal microscopy. Results: RANKL mRNA levels were higher in periodontitis than in healthy subjects and spontaneous and LPSand PHA-stimulated RANKL synthesis were higher also in patients than controls. CD4+ T lymphocytes were the predominant infiltrate cell subset present in gingival tissues of periodontitis patients. Furthermore, an association between RANKL and CD4+ T cells was determined by double-staining flow cytometry and confocal microscopy. Conclusion: Taken together, these data demonstrate that gingival CD4+ T cells are the main cells responsible for the higher levels of RANKL observed in chronic periodontitis human patients.

Keywords : Periodontitis; RANKL; lymphocytes; CD4.

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