Role of gelatinase B and elastase in human polymorphonuclear neutrophil migration across basement membrane

Polymorphonuclear neutrophil (PMN) migration across basement membrane is thought to be dependent on the degradation of membrane constituents. PMN gelatinase B, a metalloproteinase able to degrade type IV collagen, may be involved in this phenomenon. PMN gelatinase B is released in the extracellular medium as a latent preform and then activated, mainly by PMN elastase. We investigated the role of gelatinase B in PMN migration across a Matrigel(R) basement membrane matrix coated onto a filter, in a Boyden chamber. The effects of gelatinase and elastase inhibitors on PMN migration in this system were tested. Chemokinesis of PMN was tested in the same Boyden chamber across a filter free of basement membrane. The agarose method was used to test the same inhibitors for effects on PMN chemotaxis. In both systems, FMLP 10(-7) M was used as a chemoattractant. Addition of 10(-8) M TIMP-1 (the preferential gelatinase B inhibitor) inhibited trans-basement membrane PMN migration by 52 +/- 6% (P < 0.05), without affecting PMN chemokinesis, chemotaxis, or degranulation. Also, (Ala)(2) Pro Val chloromethyl ketone (AAPVCK) 100 mu m, a specific elastase inhibitor, inhibited trans-basement membrane PMN migration by 51 +/- 8% (P < 0.05), without affecting PMN chemokinesis, chemotaxis, or degranulation. The AAPVCK-TIMP combination led to a decrease in migration across Matrigel(R) basement membrane (46 +/- 2%, P < 0.05) similar to that seen with TIMP alone. AAPVCK was responsible for inhibition of gelatinase B activation, leading to a decrease in activated gelatinase from 14% to 2% of total gelatinase release (P < 0.05). All these results strongly suggest that gelatinase B is a major factor of PMN migration across basement membrane and that elastase may contribute to this process by activating pro-gelatinase B.