Expression of proteases in giant cell lesions of the jaws, tendon sheath and salivary glands.

BACKGROUND

Peripheral giant cell granuloma (GC) of the jaw is a tumour-like lesion, situated on the gingiva. The aim of this study was to: (a) better define the cellular compartments of the lesion and (b) compare the protease expression-profile in GC lesions of the jaws to GC lesions of other sites.

METHODS

This study comprised 54 GC lesions (jaws: 30, tendon sheaths: 22, salivary glands: 2). A microarray technique was applied to the study of osteoclast-specific or osteoclast-like features of different sites (CD68, CD51, RANK, M-CSF). Proteases were immunohistochemically identified [cathepsin K, L, S and matrix metalloproteinase 9 (MMP9)].

RESULTS

The GC of all lesions were immunoreactive for CD68 and CD51. Factors indicating the differentiation and activation of osteoclasts were detected in all lesions (RANK, M-CSF, cathepsin K, MMP9). The expression profile of M-CSF in GC and stroma cells was of a medium grade in cases with no apparent destruction of bone, whereas RANK was expressed only weakly in mono- or multinuclear CD68-positive cells.

CONCLUSIONS

The results of this study reveal an identical cellular composition for all lesions irrespective of site. GC of lesions at all sites contain the same osteolytic proteases and express cytokines that are effective in bone metabolism. The reason for the absence of osteolysis in some 'epulis' cases may be due to the topography of the lesion. Furthermore, the reduced number of binding sites, revealed by the low expression profile of RANK, may possibly be responsible for an absence of or only superficial osteolysis in these cases, despite evidence of M-CSF.