Cystathionine γ-Lyase Deficiency Exacerbates CCl 4 -Induced Acute Hepatitis and Fibrosis in the Mouse Liver.

AIMS: The present study examined the role of cystathionine γ-lyase (CSE) in carbon tetrachloride (CCl4 )-induced liver damage.

RESULTS: A CSE gene knock-out and luciferase gene knock-in (KI) mouse model was constructed to study the function of CSE and to trace its expression in living status. CCl4 or lipopolysaccharide markedly downregulated CSE expression in the liver of mice. CSE-deficient mice showed increased serum alanine aminotransferase and aspartate aminotransferase levels, and liver damage after CCl4 challenge, whereas albumin and endogenous hydrogen sulfide (H2 S) levels decreased significantly. CSE knockout mice showed increased serum homocysteine levels, upregulation of inflammatory cytokines, and increased autophagy and IκB-α degradation in the liver in response to CCl4 treatment. The increase in pro-inflammatory cytokines, including tumor necrosis factor-alpha in CSE-deficient mice after CCl4 challenge, was accompanied by a significant increase in liver tissue hydroxyproline and α-smooth muscle actin and histopathologic changes in the liver. However, H2 S donor pretreatment effectively attenuated most of these imbalances.

INNOVATION: Here, a CSE knock-out and luciferase KI mouse model was established for the first time to study the transcriptional regulation of CSE expression in real time in a non-invasive manner, providing information on the effects and potential mechanisms of CSE on CCl4 -induced liver injury.

CONCLUSION: CSE deficiency increases pro-inflammatory cytokines in the liver and exacerbates acute hepatitis and liver fibrosis by reducing H2 S production from L-cysteine in the liver. The present data suggest the potential of an H2 S donor for the treatment of liver diseases such as toxic hepatitis and fibrosis. Antioxid. Redox Signal. 27, 133-149.