Thioacetamide-induced liver fibrosis is reduced in humanized immune system mice

Abstract

Abstract Fibrosis is defined as a consequence of the abnormal wound-healing response lading to excessive deposition of extracellular matrix components. Chronic liver diseases accompanied with liver fibrosis have caused increased morbidity and mortality worldwide. Carbon tetrachloride (CCl 4) and thioacetamide (TAA) are the well-known toxins used to induce liver fibrosis in murine. Compared to CCl 4, TAA displays a longer latency between exposures to the drug and less safety concerns with operators. In addition, the translation of murine experimental data to human events often fails due to differences in the immune system of both species, indicating that humanized mice may be a better choice to model human diseases. The effect of TAA in humanized mice is still unknown. In our study, liver fibrosis in wild type mice was induced by escalating doses of TAA. Results showed that liver fibrosis evaluated by Sirius red staining was significantly induced (Metavir score, F2). In addition, serum levels of AST, ALT and ALP were significantly increased after TAA injection. Humanized mice were generated by injection of human hematopoietic stem cells (hHSC) into NOD.Cg-PrkdcscidIl2rgtm1Wjl/YckNarl (Advanced Severe ImmunoDeficiency (ASID)) mice, termed as hHSC-ASID. The escalating doses of TAA were introduced into hHSC-ASID and ASID mice. Although the serum levels of AST, ALT and ALP were increased in both hHSC-ASID and ASID mice following TAA injection, the degree of liver fibrosis was reduced in hHSC-ASID mice than in ASID mice (Metavir score, F1 vs. F2). These results indicated that human immune cells reduced TAA-induced liver fibrosis. It is worthwhile to assess which immune cell(s) participates in this process.