Notably, TIMP-1 deficiency resulted in an unanticipated reduced survival rate post-IRI (37% versus 100%; P < 0.05). Only three out of the eight TIMP-1−/− mice survived after reperfusion, whereas all eight TIMP-1+/+ WT animals recovered from injury and survived up to 7 days post-IRI (Fig. 2). TIMP-1−/− mice failed to recover from the injury and succumbed between the second and fourth day post-IRI. Therefore, these results indicate an important role for TIMP-1 expression in hepatic IRI. There were no detectable differences in liver histology and

transaminase levels between naive TIMP-1−/− and naive WT mice. WT livers were characterized by significant sinusoidal congestion and extensive necrosis after reperfusion; however, TIMP-1 deficiency was associated with further lobular architecture disruption at 6 hours, Proteasome inhibitors in cancer therapy 48 hours, and 7 days post-IRI (Fig. 3A). Indeed, TIMP-1−/− mice demonstrated 2 to 3-fold higher levels of hepatocellular necrosis (P < 0.05) when compared with TIMP-1+/+ mice at 48 hours post-IRI (Fig. 3B). TIMP-1−/− check details mice that survived surgery showed improved liver histology at 7 days post-IRI; however, levels of liver necrosis

were still higher in these mice when compared to respective WT controls (Fig. 3A,B). The serum transaminase levels (U/L) were significantly increased in TIMP-1 mice at 6 hours (sAST: 30,040 ± 12,104 versus 16,033 ± 6,598, P < 0.05; sALT: 40,660 ± 21,970 versus 18,148 ± 8,727, P < 0.05), 48 hours (sAST: 3,290 ± 2,170 versus 197.75 ± 82.44, P < 0.05; sALT: 6,720 ± 5,298 versus 571.25 ± 348.9, P < 0.05), and 7 days (sAST: 1,909 ± 155 versus 1,472 ± 62, P < 0.05; sALT: 254 ± 88

versus 119 ± 42, P < 0.05) post-IRI (Fig. 3C). Altogether, these data emphasize the concept that TIMP-1 has a protective function in hepatic IRI. TIMP-1−/− mice showed significantly up-regulated MMP-9/β-actin mRNA expression at 6 hours (0.44 ± 0.17 versus MCE公司 0.20 ± 0.11; P < 0.05), 48 hours (0.53 ± 0.15 versus 0.29 ± 0.07; P < 0.05), and 7 days (0.48 ± 0.13 versus 0.19 ± 0.14; P < 0.05) after IRI (Fig. 4A). Moreover, zymography analysis showed that MMP-9 activity was almost undetected in naive livers and highly expressed in TIMP-1−/− and WT livers post-IRI; however, MMP-9 activity was markedly up-regulated in the livers of TIMP-1−/− mice after 6 hours (P < 0.05) and 48 hours (P < 0.05) of reperfusion as compared to controls (Fig. 4B). Indeed, the MMP-9 activity increase observed in the TIMP-1−/− mice was over 4-fold that obtained in the control animals at 48 hours post-IRI (Fig. 4C). Finally, MMP-9+ leukocytes were present in significantly higher numbers in TIMP-1−/− livers at 6 hours (52 ± 3 versus 35 ± 14; P < 0.05), 48 hours (123 ± 13 versus 87 ± 12; P < 0.05), and 7 days (32 ± 4 versus 15 ± 3; P < 0.05) post-IRI (Fig. 4D,E). Thus, TIMP-1 deficiency is correlated with increased levels of MMP-9 expression/activity in hepatic IRI.