Mechanism of action of blueberry combined with probiotics in improving nonalcoholic fatty liver disease by affecting the JAK1/STAT3/BAX signaling pathway regulated by interleukin-22

Objective To investigate the effect of blueberry combined with probiotics on the JAK1/STAT3/BAX signaling pathway regulated by interleukin-22 (IL-22) and their mechanism of action in improving nonalcoholic fatty liver disease (NAFLD) . Methods A total of40 clean Sprague-Dawley rats were divided into normal control group (CG group) , IL-22 siRNA-negative control group (IL-22 SI-NC group) , IL-22 siRNA group (IL-22 SI group) , IL-22 siRNA-negative control + blueberry-probiotics group (IL-22 SI-NC + BPG group) , and IL-22 siRNA + blueberry-probiotics group (IL-22 SI + BPG group) . The rats in the CG group were given 100% normal diet, and the rats in all the other groups were given compound high-fat diet to establish a rat model of fatty liver and were then given the injection of IL-22 siRNA-negative control lentivirus or IL-22 siRNA lentivirus at the abdominal liver area (blind puncture) every other day for 12 weeks in total. The liver was harvested to confirm whether the model was established successfully or not and the effect of siRNA, and then the above groups were given normal diet and blueberry-probiotics solution by gavage. The rats were observed for 8 weeks. One-way analysis of variance was used for comparison between multiple groups; the SNK test (q test) was used for further pairwise comparisons of data with homogeneity of variance, while the Tamhane' s test (q' test) was used for the data with heterogeneity of variance. Results Compared with the IL-22 SI-NC group, the IL-22 SI group had significant increases in alanine aminotransferase (ALT) , aspartate aminotransferase (AST) , total cholesterol (TC) , triglyceride (TG) , and low-density lipoprotein (LDL) (all P < 0. 01) , a significant reduction in high-density lipoprotein (HDL) (P < 0. 01) , significant reductions in the mRNA and protein expression of IL-22, JAK1, and STAT3 (all P < 0. 01) , and a significant increase in the expression of Bcl-2-associated X protein (BAX) (P < 0. 01) . Compared with the IL-22 SI-NC group, the IL-22 SI-NC + BPG group had significant reductions in ALT, AST, TC, TG, and LDL (all P < 0. 01) , a significant increase in HDL (P < 0. 01) , significant increases in the mRNA and protein expression of IL-22, JAK1, and STAT3 (all P <0. 01) , and a significant reduction in BAX (P < 0. 01) . Compared with the IL-22 SI group, the IL-22 SI + BPG group had significant reductions in ALT, AST, TC, TG, and LDL (all P < 0. 05) , a significant increase in HDL (P < 0. 05) , significant increases in the mRNA and protein expression of IL-22, JAK1, and STAT3 (all P < 0. 05) , and a significant reduction in BAX (P < 0. 05) . Conclusion Blueberry combined with probiotics can antagonize hepatocyte fatty degeneration accelerated by IL-22 siRNA to a certain degree and increase the expression of IL-22, indicating that IL-22 may be a key factor for blueberry combined with probiotics in improving NAFLD. It is speculated that blueberry combined with probiotics can enhance the expression of IL-22, activate the JAK1/STAT3 signaling pathway to inhibit the expression of the downstream apoptotic factor BAX, reduce hepatocyte apoptosis, increase cholesterol metabolism, reduce lipid deposition, and thus improve NAFLD. Therefore, it is considered an adjuvant therapeutic regimen for NAFLD.