Study of endoplasmic reticulum stress role in hepatic failure induced by severe hepatitis B

Objective To investigate the endoplasmic reticulum stress (ERS) role in the course of liver failure induced by severe hepatitis B virus (HBV) infection and its related mechanism. Methods Liver tissue samples and clinical data [chronic hepatitis B patients (12 cases, chronic hepatitis B group), hepatic failure induced by severe hepatitis B virus (12 cases, severe hepatitis B virus liver failure group), and normal subjects (8 cases, control group)] were collected from the Beijing You'an Hospital affiliated to Capital Medical University between 2009 to 2011. Statistical analysis was performed on the clinical indicators of each group. The structure of endoplasmic reticulum in liver tissue was observed by transmission electron microscopy. Western blot and qRT-PCR were used to detect the expression of endoplasmic reticulum stress and apoptosis-related factors, including glucose-regulated protein (Grp), and C/EBP homologous protein (CHOP). Frozen sections of liver tissues were prepared for immunofluorescence test. All data were expressed as mean ± standard deviation. LSD-t test was used to compare the results between groups. A p value < 0.05 was considered as statistically significant. Results Transmission electron microscopy showed that the morphological structure of the endoplasmic reticulum was damaged in both groups (chronic hepatitis B and liver failure induced by severe hepatitis B virus), and liver failure induced by severe hepatitis B virus group was more critical. Western blot and qRT-PCR showed that Grp78, Grp94 and Caspase-4 were highly expressed in normal group and chronic hepatitis B group, and the relative protein expressions were 1.20 ± 0.13 and 0.78 ± 0.11, 0.90 ± 0.06 and 0.11 ± 0.01, 0.15 ± 0.02 and 0.22 ± 0.04, respectively. The expression of protein was weakened in liver failure induced by severe hepatitis B virus group (relative protein expression was 0.01 ± 0, 0.01 ± 0, and 0.11 ± 0.02, respectively).There was a statistically significant difference between the two groups (P < 0.05). The expression of CHOP was consistent with the results of immunofluorescence, and increased with the stressing of injury. Conclusion During the course of severe hepatitis B infection, dysregulated endoplasmic reticulum stress activated mild stress in chronic hepatitis B group, while severe stress in hepatic failure induced by severe hepatitis B virus group. Therefore, endoplasmic reticulum stress plays an important and complex role in the pathogenesis of hepatic failure induced by severe hepatitis B virus. Key words: Hepatitis B; Severe hepatitis; Liver failure; Endoplasmic reticulum stress; Mechanisms