Bixin Attenuates High-Fat Diet-Caused Liver Steatosis and Inflammatory Injury through Nrf2/PPARα Signals

Figure 7

Bixin attenuates the hepatic inflammation and blunts the liver abnormality through Nrf2. (a) Liver tissue sections from each group of mice were subjected to IHC staining of p-P65. (b) The total RNA from different group was extracted. mRNA levels of P62, Nrf2, HO-1, NQO1, IL-6, and TNF-α were measured by qRT-PCR assay; results are expressed as the (, Ctrl vs. treatment groups; ^#, FFA group vs. FFA+bixin group). (c) The IHC staining of 8-oxo-dG in the liver tissue from the HFD and bixin+HFD groups of Nrf2 WT and KO mice was performed. (d) TUNEL staining of liver tissue from the HFD and bixin+HFD groups of Nrf2 WT and KO mice (DAPI indicates the nucleus in liver tissues). Representative images from each group are shown (; or 100 μm; , Ctrl vs. treatment groups; ^#, HFD group vs. HFD+bixin group). (e) Proposed model for the therapeutic action of bixin against NAFLD: bixin administration could activate Nrf2 signals through two different mechanisms: (i) canonical mechanism, which modifies the critical cysteine residues in Keap1, leading to a conformational change of Keap1-Cul3-E3 complex that releases the bind with DLG motif of Nrf2 and subsequently stabilized Nrf2 and (ii) noncanonical mechanism that P62 binds with the Kelch domain of Keap1 with its pSTGE motif to stabilize Nrf2. The upregulation of Nrf2 improves the hepatic steatosis and inflammatory damage.

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