ABSTRACT
BACKGROUND: Heme oxygenase (HO)-1 is a stress-inducible protein that confers cytoprotection, but its role in gingiva during cyclosporin A (CsA) therapy is unknown. We used in vivo and in vitro models to investigate the expression of mRNA and protein for HO-1 in gingiva upon CsA treatment. METHODS: Twenty-six male Sprague-Dawley rats were assigned to two groups after the establishment of edentulous ridges. Rats in the CsA group received CsA, 30 mg/kg/day for 4 weeks, whereas control rats received mineral oil only. All rats were killed after 4 weeks, and the edentulous gingivae were excised. mRNA and protein expression of HO-1 in gingivae were determined using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC), respectively. For the in vitro study, cultured human gingival fibroblasts were harvested after treatment with various concentrations of CsA, and HO-1 mRNA and protein expression were determined using RT-PCR and Western blotting, respectively. RESULTS: Mean gingival HO-1 mRNA expression was greater in the CsA group than in the control animals (P = 0.076). IHC staining for HO-1 protein was significantly greater in the gingivae of CsA-treated rats than in those of the control group. In fibroblast cultures, expression of HO-1 mRNA and protein also increased significantly after CsA treatment. CONCLUSION: CsA upregulates the gingival expression of HO-1, which may exert a cytoprotective effect.