A critical role for matrix metalloproteinases in liver regeneration.
BACKGROUND
Matrix metalloproteinases (MMPs), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) are mediators of liver regeneration. To determine whether MMPs are required for normal hepatic regeneration, we performed 67% hepatectomies on mice treated with a broad-spectrum MMP-inhibitor, and assessed the effect on liver regeneration and urinary MMP activity.


METHODS
Mice were subjected to sham operations, 67% hepatectomy, or 67% hepatectomy plus treatment with the broad-spectrum MMP inhibitor Marimastat. Urine collected preoperatively and for 8 d postoperatively was tested for MMP-2 and MMP-9 activity using zymography. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, TNF-alpha, IL-6, and hepatocyte growth factor levels were measured. Liver sections were analyzed by CD31 immunohistochemistry and microvessel density. Mitotic index and proliferating cell nuclear antigen labeling index were determined.


RESULTS
The mean regenerating liver weight on postoperative day 8 was 0.72 +/- 0.01 grams for the hepatectomy Marimastat group, and 0.83 +/- 0.02 grams for the hepatectomy control group (P < 0.001). Urinary MMP-9 activity was elevated during hepatic regeneration, and decreased on postoperative day 8 when the liver returned to its preoperative mass. In contrast, urine from hepatectomy Marimastat mice, in which liver regeneration was successfully inhibited, showed consistently low levels of MMP-2 and MMP-9 activity. The hepatectomy Marimastat group also exhibited elevated serum IL-6 levels on post-operative day 8, while serum TNF-alpha soluble receptor II levels were unchanged. Hepatocyte growth factor levels were not significantly different between the control hepatectomy and hepatectomy Marimastat groups at days 2, 4, and 8. Liver microvessel density was reduced in the hepatectomy Marimastat group at day 4. Mitotic index and proliferating cell nuclear antigen index were significantly decreased in the Marimastat hepatectomy group at post-operative day 2.


CONCLUSIONS
The broad-spectrum MMP-inhibitor Marimastat inhibits liver regeneration. Microvessel density is reduced at day 4. Furthermore, urinary MMP-9 is elevated during liver regeneration, and this effect is not observed when regeneration is inhibited by the broad-spectrum MMP-inhibitor Marimastat.
Alwayn
Ian P J
IP
Department of Surgery and The Vascular Biology Program, Children's Hospital, Boston, Massachusetts 02115, USA.
Verbesey
Jennifer E
JE
Kim
Sendia
S
Roy
Roopali
R
Arsenault
Danielle A
DA
Greene
Arin K
AK
Novak
Katherine
K
Laforme
Andrea
A
Lee
Sang
S
Moses
Marsha A
MA
Puder
Mark
M
D000818:Animals; D001835:Body Weight; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006498:Hepatectomy; D017228:Hepatocyte Growth Factor / Q000097:blood; D006877:Hydroxamic Acids / Q000494:pharmacology; D015850:Interleukin-6 / Q000097:blood; D008099:Liver / Q000033:anatomy & histology / Q000098:blood supply / Q000201:enzymology*; D008111:Liver Function Tests; D008115:Liver Regeneration / Q000187:drug effects / Q000502:physiology*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000502:physiology; D009929:Organ Size; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D015850:Interleukin-6; D061965:Matrix Metalloproteinase Inhibitors; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D017228:Hepatocyte Growth Factor; C100342:marimastat; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9