Expression and induction of collagenases (MMP-8 and -13) in plasma cells associated with bone-destructive lesions.

Matrix metalloproteinases (MMPs) collectively degrade extracellular matrix and basement membrane proteins in chronic inflammation and bone-destructive lesions. This study examined the ability of immunoglobulin-producing plasma cells, typically present in sites of chronic inflammation, to express collagenases (MMP-8 and -13) in vivo and in vitro. Phorbol-12-myristate-13-acetate, interleukin-6, and tumour necrosis factor-alpha and heparin with the tumour promoter or cytokines potently enhanced (up to nine-fold) MMP-8 and -13 expression by the RPMI 8226 myeloma cell line, as evidenced by western blotting and semi-quantitative reverse transcriptase-polymerase chain reaction. Immunohistochemical analysis and in situ hybridization revealed that plasma cells expressed MMP-8 and -13 focally in periapical granulomas, odontogenic cysts, and malignant plasmacytomas. MMP-8 and MMP-13 from plasma cells can participate in bone organic matrix destruction at sites of chronic inflammation and neoplastic growth. Since MMP-13 was more frequently expressed than MMP-8 in plasma cells of strongly recurring keratocysts and malignant plasmacytomas, it is concluded that plasma cell MMP-13 has a particularly important role in benign and malignant bone-destructive lesions.