Upregulation of lysyl oxidase expression in cyclosporin A-induced gingival overgrowth

Abstract

Lysyl oxidase (LOX) is involved in the initial steps of converting soluble monomers of collagen and elastin into insoluble fibers in the extracellular matrix. LOX was found to be upregulated in some fibrotic diseases. However, little is known about the correlation between LOX and cyclosporin A (CsA)-induced gingival overgrowth. The aim of this study was to compare LOX expression in normal healthy gingival tissues and CsA-induced gingival overgrowth specimens. Fifteen CsA-induced gingival overgrowth specimens and five normal gingival tissues were examined by immunohistochemistry. Three oral submucous fibrosis specimens were used as positive controls. In addition, one section from each CsA-induced gingival overgrowth specimen was stained with hematoxylin and eosin to evaluate the magnitude of inflammation at the histologic level. Differences in LOX expression between tissues with low and high levels of inflammation were subsequently analyzed using Fisher's exact test. LOX staining in gingival tissue was stronger in the CsA-induced gingival over-growth group than in the normal gingival group (P < 0.05). LOX staining was detected in the epithelium, connective tissue, inflammatory infiltrates, and endothelium. The LOX signal was mainly expressed in inflammatory cells (100%), followed by endothelial cells (93.3%), fibroblasts (80%) and epithelial cells (60%). In addition, LOX expression was significantly higher in CsA-induced gingival overgrowth specimens with higher levels of inflammatory infiltrates (P = 0.017). LOX expression was significantly upregulated in CsA-induced gingival overgrowth specimens. In addition, the expression of LOX increased with the grade of inflammation in CsA-induced gingival overgrowth.