Cell type-specific release of matrix-metallo-proteinase-9 by bacterial chemoattractant in human blood phagocytic leukocytes

Stimulation of phagocytic leukocytes with bacterial chemoattractant resulted in the release of matrix metalloproteinases (MMPs). Little is known about the mechanisms of bacterial chemoattractant regulation of MMP in phagocytic leukocytes. We report here that the mechanisms of the bacterial chemotactic peptide fMLP-induced MMP -9 release in monocytes appeared to be different from fMLP-stimulated MMP-9 release in neutrophils. In freshly prepared peripheral blood monocytes, fMLP induces MMP-9 release, starting at 8 h after stimulation. These functions of fMLP is accompanied by an increase in TNFα expression, and mediated through the phosphorylation of ERK1/2 in monocytes. However, neutrophil preparations that responded to fMLP with MMP-9 release did not require activation of ERK1/2 and TNFα expression. These results suggest a different role of fMLP in MMP-9 expression in neutrophils and monocytes, and the signal molecules involved in mediating this effect in human blood monocytes stimulated by bacterial chemoattractant.