【Animal Modeling】-NOD2 promotes the production of nitrosamine by diethyl nitrosamine to study the mechanism of inducing liver tissue inflammation in mice

  Objective To investigate the role and mechanism of NOD2, a pattern recognition receptor in hepatocytes, in the process of hepatic inflammation.

  Methods The NOD2 knockout mice injected with diethylnitrosamine (DEN) were used as the Nod2△hep model group, and the B6/JNju-Nod2em1Cflox/Gpt(Nod2f/f) mice injected with DEN were used as the Nod2f/f model. group, NOD2 knockout mice without DEN injection were Nod2△hep group, Nod2f/f mice without DEN injection were Nod2f/f group. HE staining was used to detect liver pathological damage, and ALT and AST kits were used to detect the changes of ALT and AST levels in serum; F4/80 immunohistochemical staining was performed on the liver tissue of mice to detect the number of hepatitis cells and qPCR to detect inflammatory factors in hepatocytes The gene expression level and the expression level of NOD2 in hepatocytes; Ki67 immunohistochemical staining and TUNEL staining were used to detect the effect of DEN on hepatocyte proliferation and apoptosis; Western Blot was used to detect NF-κB, MAPK and STAT3 signaling pathway-related protein molecules in liver tissue. expression.

  Results Compared with the Nod2f/f model group, the liver injury in the Nod2△hep model group was significantly relieved, manifested as cell necrosis and vacuolation formation, and serum ALT and AST levels were significantly decreased (P<0.01); In addition, compared with the Nod2f/f model group, the gene expression levels of liver tissue inflammatory factors TNF-α, IL-6, IFN-γ and IL-1β, the number of F4 / 80 positive cells in liver tissue and the The proliferation and apoptosis of hepatocytes were significantly decreased (P< 0. 01); Western Blot expression results showed that P38, ERK, JNK, p65 and JAK2 / STAT3 protein phosphorylation in the liver tissue of Nod2△hep model group mice Compared with the Nod2f/f model group, the levels were significantly lower (P<0.05), while the above-mentioned indexes of the mice in the Nod2△hep group and Nod2f/f group were not significantly abnormal.

  Conclusion Liver NOD2 deletion can reduce the inflammation and necrosis of hepatocytes in mice, and the mechanism may be related to the down-regulation of the expression of NF-κB, MAPK and STAT3 signaling pathway-related factors in liver tissue.