Potentiation of matrix metalloproteinase (MMP) protein expression in human fibroblasts by Staphylococcus aureus grown in the presence of recombinant human interleukin (rhIL)-1β. The cell pellets from S. aureus grown in the presence or absence of rhIL-1β were washed repeatedly to prepare cell lysate. Enzyme-linked immunosorbent assay (R&D Systems, Inc., Minneapolis, MN, USA) was carried out to make sure that the bacterial cell lysate was devoid of any traces of rhIL-1β. Confluent monolayers of human dermal fibroblasts were exposed to 25 μg/well of IL-1β-free cell lysate obtained from S. aureus for 48 hours. The supernatants were collected and expression of multiple MMP protein was assessed using multi-MMP-Array kit from RayBiotech, Inc. (Norcross, GA, USA) as described in the text. The data presented show that MMP-2, -3, and 8 are relatively more expressed in fibroblasts treated with S. aureus cell lysate obtained from strain grown in the presence of 5 and 15 ng/ml rhIL-1β. Tissue inhibitor of metalloproteinases (TIMP)-4 expression was also slightly enhanced in fibroblasts treated with S. aureus lysate obtained from strain treated with 15 ng/ml IL-1β.