| Cyclosporin A(CsA) is a potent immunosuppressant widely used to prevent organ transplant rejection and for the treatment of some autoimmune disorders. However, its significant adverse effect in oral cavity was gingival overgrowth (GO) which includes gingival epithelium overgrowth in pathology. At present, the mechanism of CsA associated gingival epithelium overgrowth is not clear. The present study established a mice animal model of CsA-induced gingival overgrowth by gastric feeding, and determined the affected parts of gingival epithelium, such as oral epithelium (OE), sulcular epithelium (SE) and oral sulcular epithelium (OSE), and the time of appearance of GO by stereometric analysis. On the basis of that, the effect of CsA on the apoptosis of epithelial cell in murine gingival tissue and palatal mucosa, was assessed by in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine-5' -triphosphate(dUTP) nick end labeling(TUNEL) assay to investigate the mechanism of CsA-induced gingival epithelial hyperplasia.PART I Establishment of Animal Model about Mice Gingival Overgrowth Induced by CsA[Materials and methods] 100, 6-week-old male, ICR mice were randomly assigned to test and control groups of 50 each. Mice in the test group received CsA dissolved in olive oil (30mgCsA/kg body weight) daily through gastric feeding. And the control group received only olive oil. Ten animals from each group were chosen randomly to sacrifice after 1, 2, 4, 6 and 8 wk, respectively, after having been observed the color and the shape changes of the gingival tissue alive under stereoscope. 4μmserial longitudinal-sections were processed, for histopathological examination, in the gingivae of central incisors and the palatal mucosa.[Results] Redness can be found in gingival mucosa of some 2wk and all 4wk test mice whereas pink in all contol ones; and gingivae appeared hypertrophy in the majority of CsA-exposed mice after 4wk. After 2wk, slightly thicker gingival epithelium and vascularization in subbasal lamina propria can be observed in test group. After 4 wk, the increased thickness of gingival epithelia including acanthosis was mainly in marginal gingivae from which rete pegs occurred frequently and elongated into lamina propria, even showing reticular occasionally. The accumulation of extracellular matrix, and the increase number of fibroblasts and proliferative capillary vessels, could be found in lamina propria simultaneously. After 8wk, the matrix accumulation was more significant than that in 4wk. There are no significant changes in palatal mucosa.[Conclusions] 30mg/kg/d CsA may lead to GO observed by stereoscope and histopathology in mice by gastric feeding. This animal model of CsA-induced GO can be considered as a base for further study, since the histopathological features of GO in mice basically agree with that in other animals and clinical patients.PART II Effects of CsA on Mice Gingivae Evaluated by Using Histopathological Stereometry of Model[Materials and methods] Under stereoscope, the dimensions were measured by vernier calipers in the interdental papilla between mandibular central incisors in the aforementioned specimens. And the volumes of gingival papilla were calculated. Then, 4 consecutive longitudinal-sections from each mouse were used to determine the gingival epithelium thicknesses of different parts (including SE, OSE and OE) by histometry. And the epithelial thickness of palatal mucosa was also measured.[Results] The volumes of gingival papillae were significantly larger inCsA-exposed group than in the control after 4, 6 and 8wk. And the OSE was obviously thicker in CsA group at all observation time except for 1wk, especially after 4wk, though it after 8wk grew thinner almost as that after 2wk in CsA group. The results from the histometric evaluation in three different parts showed that the increase of epithelial thickness was more prominent in OSE than that in SE. Interestingly, the epithelial thickness in CsA-treated OE showed hardly increase compared to the control group in any time as well... |
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