Measuring matrix metalloproteinase activity in macrophages and polymorphonuclear leukocytes.

Macrophages and polymorphonuclear cells (PMNs) represent an essential part of the innate immune system. These cells mediate a wide spectrum of immunological functions including bacterial defense, immune modulation, and inflammation; they are necessary for tissue homeostasis and also contribute to pathologies such as malignancy, autoimmunity, and chronic inflammation. Both macrophages and PMNs express a set of matrix metalloproteinases (MMPs), zinc-dependent endopeptidases that are involved in a variety of biological functions such as the turnover of extracellular matrix (ECM) components, angiogenesis, and the regulation of inflammation. Given the link between unregulated MMP function and diseases such as chronic inflammation or cancer, it is not surprising that these enzymes have been implicated as key effectors in clinical studies. Thus, it is important to widen our knowledge about the role of these enzymes in macrophage and PMN biology. Here, we briefly discuss the general role of inflammatory cell-derived MMPs and describe methods to analyze their activity in macrophages and PMN.