Induction of multiple matrix metalloproteinase (MMP) mRNAs in human synovial fibroblasts (SFs) by Staphylococcus aureus. MMP mRNA expression profile in confluent monolayers of SFs obtained from de-identified (a) rheumatoid arthritis (RA) and (b) osteoarthritis (OA) patients treated with culture supernatants (SUP) (25 μg of total protein/well) and cell lysates (25 μg of total protein/well) were determined using SYBR green real-time reverse transcription-polymerase chain reaction. Unlike untreated dermal fibroblasts, untreated SFs from RA and OA patients had higher basal multiple MMP mRNA expression. Similar to the dermal fibroblasts, most MMP mRNAs tested were elevated in RA and OA fibroblasts in response to S. aureus cell lysate and culture supernatants. Levels of significantly elevated MMPs (MMP-1, -2, -3, -7, -10, and -11; p < 0.05) are shown in (a) and (b). The MMP mRNA expression pattern in response to IL-1β/TNF-α and S. aureus lysate was similar in RA and OA fibroblasts. IL, interleukin; TNF, tumor necrosis factor.