Matrix metalloproteinases as regulators of inflammatory processes.

Inflammation is a central mechanism for dealing with insults to tissue, either from pathogenic invaders or by other damage-inducing means, such that the threat is removed, the tissue is healed and there is a return to homeostasis. It is a multi-step process with manifold methods of regulation built in. Proteolysis is one such regulatory method and members of the matrix metalloproteinase (MMP) family of proteinases have been shown to influence inflammation in myriad of ways. It is becoming more and more clear that no single MMP can be unequivocally labeled as 'good' or 'bad' when considering inflammation in general - the net result of proteolytic activity is dependent on context. Here we provide examples from recent literature, with a focus on in vivo studies, to highlight this concept. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.