Human Papillomavirus Infection in Cyclosporin-induced Gingival Overgrowth in Renal Allograft Recipients

Background: Host immunity plays an important role in the development of human papillomavirus (HPV)-associated disease. The HPV infection in oral cyclosporin-induced gingival overgrowth in renal transplant recipients has not been investigated previously. The aim of this study was to establish the HPV infection of cyclosporin-induced gingival hyperplasia in renal transplant recipients through morphological changes and use of the in situ hybridization technique.

Methods: We examined 13 renal transplant recipient biopsies with gingival overgrowth lesions and 4 healthy mucosa samples of these patients. The histopathological diagnoses were established on the basis of widely accepted criteria, and the pathologist was not aware of the HPV result. An in situ molecular hybridization was carried out under low stringent conditions to detect HPV species with mixed biotin-labeled probes of HPV 6 and HPV 11, and under high stringent conditions with HPV 6, HPV 11, HPV 16, and HPV 18 probes for HPV typing.

Results: The HPV prevalence among the 13 samples studied was 92.31% (12/13), of which 4 tested positive for HPV 6-11 and 1 for HPV 16. The 4 biopsies of normal mucosa from gingival overgrowth patients were also reactive for HPV DNA. In 11/12 (91.7%) HPV-positive cases, koilocytotic atypia was found.

Conclusions: The suppression of T-cell function by cyclosporin therapy can result in an increase of HPV infection, adding to the proliferative activity of cyclosporin in the oral mucosa.