ASPP2 reduction attenuates HBV induced chronic liver damage: A hybrid mouse model study

Background & aim: P53 Apoptosis Stimulating Protein 2 (ASPP2) is confirmed to participate in cellular activities including apoptosis, proliferation, autophagy, injury and so on. However, the role of ASPP2 in Hepatitis B virus (HBV) infection has not been reported in detail. The study explored the role of ASPP2 in HBV induced chronic liver damage.
Methods: Transcriptome profiling of ASPP2-konckdown mouse liver were analyzed by RNA-sequencing. HBV-ASPP2-knockdown mice was the hybrid offspring of HBV transgenic mice and ASPP2 knockdown mice. Liver tissues were taken for the experiments such as western Blot (WB), PCR, Hematoxylin and Eosin (HE), Immunohistochemistry and high throughput sequencing of transcriptome.
Results: Pathological and transcriptomic analysis of liver tissue from ASPP2 knockdown vs con mice showed that after ASPP2 knockdown, the pathological changes in the liver tissue of mice were not significant, but transcriptomics showed obvious changes in immune system process, and response to stimulus, metabolism, Human Diseases and other directions etc. In the HBV-ASPP2-knockdown mice, liver tissue HE staining found less cell swelling and necrosis foci; F4/80 and MPO staining showed less inflammatory cell infiltration; serum ALT and AST decreased than the HBV-ASPP2-con mice. Transcriptome results showed significantly changed in HBV-ASPP2-knockdown mice including immune system process, inflammatory response, and innate immune response etc. Further comparison of the two transcriptomes yielded 9 identical pathways related to inflammatory and cell injury. The PPAR pathway was verified, and found that the increase of PPARγ caused by the reduction of ASPP2 is likely to be the reason for the reduction of HBV-related liver injury. The expression of PPARγ was then analyzed by transcriptome and PCR, it was found that in the absence of HBV, ASPP2 knockdown resulted in a mild decrease in PPARγ, and in the presence of HBV infection, ASPP2 knockdown resulted in a marked increase in PPARγ.In addition, this study found that high expression of ASPP2 had opposite effects on HCC (HBV-none) and HCC (HBV-yes).
Conclusion: This study demonstrated that reduction of ASPP2 reduces HBV-induced hepatocyte damage during chronic HBV infection. This phenomenon is related to the different regulation of PPARγ by ASPP2 in the presence or absence of HBV stimulation.