Gelatinases mediate neutrophil recruitment in vivo: evidence for stimulus specificity and a critical role in collagen IV remodeling.
In the present study, the role of gelatinases [matrix metalloproteinase-2 and -9 (MMP-2 and -9)] for leukocyte rolling, adherence, and transmigration was analyzed in the mouse cremaster muscle under different inflammatory conditions including ischemia-reperfusion (I/R) and stimulation with MIP-1alpha or platelet-activating factor (PAF). Using zymography, we detected a significant elevation of MMP-9 activity in response to the stimuli applied, and MMP-2 expression was not altered. However, treatment with a specific MMP-2/-9 inhibitor significantly abrogated elevated MMP-9 activity. As observed by intravital microscopy, all inflammatory conditions induced a significant increase in numbers of adherent and transmigrated leukocytes (>80% Ly-6G(+) neutrophils). Blockade of gelatinases significantly diminished I/R- and MIP-1alpha-induced leukocyte adherence and subsequent transmigration, and upon stimulation with PAF, gelatinase inhibition had no effect on leukocyte adherence but selectively reduced leukocyte transmigration. Concomitantly, we observed an increase in microvascular permeability after I/R and upon stimulation with MIP-1alpha or PAF, which was almost completely abolished in the inhibitor-treated groups. Using immunofluorescence staining and confocal microscopy, discontinuous expression of collagen IV, a major substrate of gelatinases within the perivascular basement membrane (BM), was detected in postcapillary venules. Analysis of intensity profiles demonstrated regions of low fluorescence intensity, whose size was enlarged significantly after I/R and upon stimulation with MIP-1alpha or PAF as compared with unstimulated controls. However, this enlargement was abolished significantly after inhibition of gelatinases, respectively. In conclusion, these data demonstrate that gelatinases strictly regulate microvascular permeability and BM remodeling during the early inflammatory response, whereas concomitant leukocyte recruitment is mediated by these proteases in a stimulus-specific manner.
Reichel
Christoph A
CA
Institute for Surgical review, University of Munich, Marchioninistr. 27, D-81377 Munich, Germany. christoph.reichel@med.uni-muenchen.de
Rehberg
Markus
M
Bihari
Peter
P
Moser
Christian M
CM
Linder
Stefan
S
Khandoga
Andrej
A
Krombach
Fritz
F
D000818:Animals; D002463:Cell Membrane Permeability; D024141:Collagen Type IV / Q000097:blood / Q000502:physiology*; D018093:Gelatinases / Q000097:blood*; D006439:Hemodynamics; D007958:Leukocyte Count; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000097:blood*; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000494:pharmacology; D019714:Tissue Inhibitor of Metalloproteinases / Q000494:pharmacology
D024141:Collagen Type IV; D019714:Tissue Inhibitor of Metalloproteinases; D019716:Tissue Inhibitor of Metalloproteinase-2; D018093:Gelatinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9