Determination of the key innate genes related to individual variation in carbon tetrachloride-induced hepatotoxicity using a pre-biopsy procedure

High inter-individual variation in chemical-induced liver injury is a frequent observation with many hepatotoxic chemicals, yet the mechanism underlying it remains poorly understood. Even with carbon tetrachloride (CCl4), a well-known model hepatotoxicant, substantial individual variations are observed in the severity of liver injury. Using microarray, many attempts have been made to identify the key genes in CCl4-induced liver injury but mostly, they examined the gene expression of liver after CCl4 exposure, unable to dissect out the complicating factors from pathological changes secondary to liver injury. To more accurately identify the genes for the individual variation in CCl4-induced hepatotoxicity, we compared the innate gene expression of the individual liver samples pre-biopsied prior to CCl4-treatment with the severity of liver injury after CCl4-treatment. Effect of biopsy procedure and 3 week recovery period on liver function and gene expression were confirmed to be insignificant. Using this design, we found that the expression of genes associated with immunity and defense, lipid metabolism, transport and complement-mediated immunity, which are previously known to be suppressed by CCl4-treatment, were innately lower in the susceptible animals than resistant animals. Moreover, we demonstrated that the genes such as Gsta2, Sult2a1, Fgl1 and C6 were newly found to be innately lower in the susceptible animals to CCl4-hepatotoxicity. These naturally lower gene expression patterns were further confirmed by RT-PCR. We believe that this pre-biopsy design may provide a useful tool for understanding the cause of variability of hepatotoxicity and for the prediction and pre-screening of the susceptible individual to drug-induced hepatotoxicity.