Up-regulation of MMP-2 and MMP-9 leads to degradation of type IV collagen during skeletal muscle reperfusion injury; protection by the MMP inhibitor, doxycycline.
OBJECTIVE
to determine the role of matrix metalloproteinases, MMP-2 and MMP-9, in reperfusion injury following skeletal muscle ischaemia and whether inhibition of MMPs by doxycycline protects against tissue damage.


METHODS
rats were anaesthetised and a tourniquet applied to the proximal thigh to occlude blood flow. Four hours of ischaemia was followed by reperfusion for 0, 4, 24 or 72 h. Two further groups received doxycycline for 7 days prior to bilateral ischaemia and 24 h reperfusion. Skeletal muscle from both limbs, kidneys and lungs were harvested for zymography and immunohistochemical staining for type IV collagen.


RESULTS
upregulation of MMP-2 and MMP-9 was detected by zymography in the ischaemic leg and lung but not in the kidney. Quantitative immunohistochemical analysis showed marked degradation of type IV collagen in reperfused muscle, lung and kidney. Doxycycline-treated rats showed significant preservation of type IV collagen in skeletal muscle and a trend towards preservation in kidney and lung.


CONCLUSIONS
MMP-2 and MMP-9 are strongly upregulated in skeletal muscle ischaemia/reperfusion injury and are also upregulated in remote organs, leading to degradation of basement membranes. Inhibition of MMP activity may therefore be potentially therapeutically useful in reducing the severity of reperfusion injury.
Roach
D M
DM
Department of Surgery, The University of Adelaide, Woodville, South Australia 5011.
Fitridge
R A
RA
Laws
P E
PE
Millard
S H
SH
Varelias
A
A
Cowled
P A
PA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D024141:Collagen Type IV / Q000502:physiology*; D004195:Disease Models, Animal; D004318:Doxycycline / Q000627:therapeutic use*; D007668:Kidney / Q000098:blood supply / Q000293:injuries / Q000503:physiopathology; D008168:Lung / Q000098:blood supply / Q000503:physiopathology; D055370:Lung Injury; D020778:Matrix Metalloproteinase 2 / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology*; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000293:injuries* / Q000503:physiopathology*; D051381:Rats; D015427:Reperfusion Injury / Q000503:physiopathology* / Q000517:prevention & control*; D015854:Up-Regulation / Q000502:physiology*
D000900:Anti-Bacterial Agents; D024141:Collagen Type IV; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D004318:Doxycycline