[Protective effect of knock-down the expression of Blimp1 gene on early liver injury in CCl4-induced mouse model of liver fibrosis].

Abstract

Objective: To explore the protective effect of knock-down the expression of B lymphocyte induced maturation protein 1 (Blimp1) gene on early liver injury in carbon tetrachloride (CCl₄)-induced mouse model of liver fibrosis.

Methods: C57BL/6 mice were intraderitoneal injected with 5% CCl₄ olive oil solution to create mouse model of hepatic fibrosis. The expression of Blimp1 gene in the mice was reduced by intraderitoneal injection of short hairpin RNA (shRNA) adeno-associated virus (AAV). The mice were randomly divided into 3 groups: blank test group (n=10), CCl₄+AAV-shRNA-NC group (n=10) and CCl₄+AAV-shRNA-Blimp1 group (n=10). After 27 days of preparation of the CCl₄ mouse model, animal materials were carried out. Western blot and real-time PCR were used to detect the levels of Blimp1, α-smooth muscle actin (α-SMA), collagen type Ⅰ alpha 1 (COL1A1), collagen type Ⅲ alpha 1 (COL3A1), and their mRNA expression levels of liver tissue in each group. The serum of each group was separated to measure aspartate transaminase (AST) and alanine transaminase (ALT) by automatic biochemical analyzer. The pathological changes of liver tissue and the degree of liver fibrosis in the mice were detected by pathological staining including hematoxylin-eosin staining, Masson, and Sirius red.

Results: The expression levels of Blimp1 protein in the liver of CCl₄+AAV-shRNA-NC group (2.036±0.244, t=3.690, P=0.002) were significantly increased than that of the blank test group. In the CCl₄+AAV-shRNA-Blimp1 group, the expression of Blimp1 protein decreased to the basal level (0.783±0.249, t=6.223, P=0.003). Compared with the serum levels of ALT [(1 957.8±633.6) U/L] and AST [(1 808.8±260.1) U/L] in the CCl₄+AAV-shRNA-NC group, the serum levels of ALT [(894.0±360.1) U/L, t=3.998, P=0.003] and AST [(820.0±100.6) U/L, t=6.141, P=0.004] in the CCl₄+AAV-shRNA-Blimp1 group were significantly decreased. The pathological results of the CCl₄+AAV-shRNA-Blimp1 group showed that compared with the CCl₄+AAV-shRNA-NC group, the infiltration of inflammatory cells in the liver tissue was reduced and the degree of fibrosis was alleviated. The level of α-SMA (0.676±0.064, t=7.930, P=0.001), COL1A1 (1.426±0.143, t=6.364, P=0.003) and COL3A1 (1.124±0.198, t=3.440, P=0.026) of liver in the CCl₄+AAV-shRNA-Blimp1 group were significantly decreased than that of CCl₄+AAV-shRNA-NC group, and the mRNA expression levels were altered as well as their protein levels.

Conclusion: Blimp1 plays an important role in CCl₄-induced liver fibrosis in mice, and knock-down the expression of Blimp1 gene is beneficial to protect early liver injury in mice.