Induction of matrix metalloproteinase (MMP)-1 and MMP-3 mRNA in response to Staphylococcus aureus components separated by molecular-weight difference. Fractionated S. aureus culture supernatant (15 μg/ml per well) obtained by centrifuging through Centricon filters with molecular-weight cutoff points <30 kDa, 30 to 50 kDa, and >50 kDa was added to confluent monolayers of dermal fibroblasts. Total RNA was isolated after 8 hours. The mRNA levels of MMP-1 and MMP-3 were measured by SYBR green real-time reverse transcription-polymerase chain reaction. The active components were mostly in the 30 to 50 and >50 kDa molecular-weight range as evidenced by significantly elevated expression of MMP-1 and MMP-3 by Centricon fractions 30 to 50 and >50 kDa (p < 0.05; 30 to 50 kDa and >50 kDa fractions were compared with <30 kDa fractions).