| 2018 | Involvement of methylation of MicroRNA-122, -125b and -106b in regulation of Cyclin G1, CAT-1 and STAT3 target genes in isoniazid-induced liver injury. | BMC Pharmacol Toxicol | This investigation aimed to evaluate the role of methylation in the regulation of microRNA (miR)-122, miR-125b and miR-106b gene expression and the expression of their target genes during isoniazid (INH)-induced liver injury.Rats were given INH 50 mg kg·d once per day for 3, 7, 10, 14, 21 and 28 days and were sacrificed. Samples of blood and liver were obtained.We analysed the methylation and expression levels of miR-122, miR-125b and miR-106b and their potential gene targets in livers. Liver tissue pathologies, histological scores and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities changed, indicating the occurrence of liver injury. Relative expression levels of miR-122, miR-125b and miR-106b genes in the liver decreased after INH administration and correlated with the scores of liver pathology and serum AST and ALT activities, suggesting that miR-122, miR-125b and miR-106b are associated with INH-induced liver injury. The amount of methylated miR-122, miR-125b and miR-106b in the liver increased after INH administration and correlated with their expression levels, suggesting the role of methylation in regulating miRNA gene expression. Two miR-122 gene targets, cell cycle protein G1 (Cyclin G1) and cationic amino acid transporter-1 (CAT-1), also increased at the mRNA and protein levels, which suggests that lower levels of miR-122 contribute to the upregulation of Cyclin G1 and CAT-1 and might play a role in INH-induced liver injury. Signal transducer and activator of transcription 3 (STAT3) was a common target gene of miR-125b and miR-106b, and its expression levels of mRNA and protein increased after INH administration. The protein expression of phosphorylated (p)-STAT3 and the mRNA expression of RAR-related orphan receptor gamma (RORγt) regulated by p-STAT3 also increased. Meanwhile, the mRNA and protein expression of interleukin (IL)-17 regulated by RORγt, and the mRNA and protein expression of CXCL1 and MIP-2 regulated by IL-17 increased after INH administration. These results demonstrate that lower levels of hepatic miR-125b and miR-106b contribute to the upregulation of STAT3 in stimulating the secretion of inflammatory factors during INH-induced liver injury.Our results suggested that DNA methylation probably regulates the expression of miRNA genes (miR-122, miR-125b, and miR-106b), affecting the expression of their gene targets (Cyclin G1, CAT-1, and STAT3) and participating in the process of INH-induced liver injury. |
| 2014 | Lack of liver injury in Wistar rats treated with the combination of isoniazid and rifampicin. | Mol Cell Biochem | Isoniazid (INH) can cause serious idiosyncratic liver injury. An animal model would greatly facilitate mechanistic studies, but it is essential that the mechanism in the model be similar to the liver injury that can occur in humans. We attempted to replicate a previous study in which Wistar rats treated with INH and rifampicin (RMP) developed liver injury, which was promising because of its delayed onset similar to the liver injury that can occur in humans. Wistar rats were treated with either a high dose of INH (150 mg/kg/day) or a combination of INH and RMP (75 mg/kg/day and 50 mg/kg/day, respectively) for up to 4 weeks. However, we did not observe any liver injury or evidence of an inflammatory infiltrate as had been reported; rather, we observed an increase in CTLA4-positive cells in the cervical lymph nodes as well as a decrease in serum CXCL1 and MCP-1. In short, we were unable to reproduce a previously reported model of delayed onset INH-induced liver injury in Wistar rats. |