ADAMTS13 Plays a Critical Role in Acetaminophen-Induced Acute Liver Injury in Mice, and Can be a Novel Therapeutic Option

【Background】 Acetaminophen (APAP) is one of the major causes of drug-induced acute liver injury. It is known that VWF deficiency reduces hepatic platelet accumulation and promotes liver repair in APAP-induced acute liver injury in mice. We hypothesized that VWF-ADAMTS13 axis plays a role in the pathophysiology of APAP-induced acute liver injury. To investigate this hypothesis, we have used a mouse experimental model of APAP-induced hepatic injury. 【Method】 The extent of APAP-induced liver injury was compared between wild-type (WT) and ADAMTS13 gene-deleted (KO) mice (C57BL/6 background). At first, mice were fasted for 24 hours before administration of 300 mg/kg APAP via intraperitoneal injection. Forty-eight hours after APAP administration, Hepatic blood flow was measured as the average of the surface blood flow on the anterior and inferior surfaces of the liver in the right and left lobes using Laser Doppler flowmetry (ALF21N, Advance Co, Tokyo, Japan), followed by sampling of blood and hepatic tissue. Blood cell counts and biochemical analysis including aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were performed. Also, histological analysis and gene expression analysis by quantitative PCR (qPCR) such as interleukin-6 (IL-6), interleukin-1beta (IL1-β), tumor necrosis factor-alfa (TNF-α), Keratinocyte-derived chemokines (KC), monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-beta (TGF-β), alfa-smooth muscle actin (α-SMA) and collagen type I alfa-1 (COL1α1) were conducted using the liver samples. In addition, to confirm whether recombinant ADAMTS13 has a protective effect against APAP-induced liver injury, we administered recombinant ADAMTS13 to WT mice through the retro-orbital cavity 30 min before APAP administration and examined whether the liver injury was reduced. 【Result】 In APAP-challenged KO mice (N=13), serum levels of AST and ALT were significantly elevated compared to WT mice (N=9)（AST; 3115.4 vs 1331.1 IU/L, ALT; 3911.5 vs 1647.8 IU/L）. The area of liver necrosis was increased in KO mice compared to WT mice （area of hepatic necrosis; 58.0 vs 42.9 %）. In addition, inflammation markers other than TNF-α and MCP-1 were not significantly different, but TNF-α and MCP-1 were significantly elevated in KO mice compared to WT mice. Furthermore, hepatic blood flow was decreased in KO mice compared to WT mice（18.3 vs 21.6 ml/hr）, in accordance with the significantly reduced levels of the numbers of platelets in KO mice（269.3 vs 503.2 x109/L）. Surprisingly, the increases of ALT values and the area of hepatic necrosis observed in WT mice were significantly suppressed by recombinant human ADAMTS13 administration. 【Discussion】 We have shown that APAP-induced liver injury is exacerbated by enhanced inflammation in KO mice and clarified that ADAMTS13 plays a critical role in the liver injury induced by APAP. Moreover, we found that recombinant human ADAMTS13 administration reduces APAP-induced hepatic injury. Our results suggest that recombinant human ADAMTS13 can be a novel therapeutic option for APAP poisoning.