Soyasaponins reduce inflammation and improve serum lipid profiles and glucose homeostasis in HFD-induced obese mice.

Scope: Nonalcoholic steatohepatitis (NASH) is a chronic progressive disease with complex pathogenesis of which the bile acids (BAs) and gut microbiota are involved. Soyasaponins (SS) exhibits many health-promoting effects including hepatoprotection, but its prevention against NASH is unclear. This study aims to investigate the preventive bioactivities of SS monomer (SS-A 2 ) against NASH and further clarify its mechanism by targeting the BAs and gut microbiota. Methods and Results: The methionine and choline deficient (MCD) diet-fed male C57BL/6 mice were intervened with obeticholic acid or SS-A 2 for 16 weeks. Hepatic pathology is assessed by hematoxylin-eosin and Masson's trichrome staining. BAs in serum, liver, and colon are measured by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQMS). Gut microbiota in caecum are determined by 16S rDNA amplicon sequencing. In the MCD diet-induced NASH mice, SS-A 2 significantly reduces hepatic steatosis, lobular inflammation, ballooning, nonalcoholic fatty liver disease activity score (NAS) scores, and fibrosis, decreases Erysipelotrichaceae (Faecalibaculum) and Lactobacillaceae (Lactobacillus) and increases Desulfovibrionaceae (Desulfovibrio). Moreover, SS-A 2 reduces serum BAs accumulation and promotes fecal BAs excretion. SS-A 2 changes the BAs profiles in both liver and serum and specifically increases the taurohyodeoxycholic acid (THDCA) level. Faecalibaculum is negatively correlated with serum THDCA. Conclusion: SS-A 2 alleviates steatohepatitis possibly through regulating BAs and gut microbiota in the MCD diet-induced NASH mice.

Background: Previous studies indicate that soyasaponins may reduce inflammation via modulating toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling. However, its underlying mechanisms are still not fully understood. Methods: Lipopolysaccharide (LPS)-challenged inflamed male ICR mice were intervened by intragastrical administration with 10 and 20 μmol/kg•BW of soyasaponin A 1 , A 2 or I for 8 weeks. The serum inflammatory markers were determined by commercial kits and the expression of molecules in TLR4/MyD88 signaling pathway in liver by real-time PCR and western blotting. The recruitments of TLR4 and MyD88 into lipid rafts of live tissue lysates were detected by sucrose gradient ultracentrifugation and western blotting. LPS-stimulated RAW264.7 macrophages were treated with 10, 20 and 40 μmol/L of soyasaponin A 1 , A 2 or I for 2 h. MyD88-overexpressed HEK293T cells were treated with 20 and 40 μmol/L of soyasaponins (A 1 , A 2 or I) or 20 μmol/L of ST2825 (a MyD88 inhibitor) for 6 h. The expression of molecules in TLR4/MyD88 signaling pathway were determined by western blotting. Data were analyzed by using one way analysis of variance or t-test by SPSS 20.0 statistical software.

To the best of our knowledge, this study firstly shows that soyasaponins (A1 & A2) exhibit antiatherosclerotic bioactivities by improving the serum lipid profile and reducing TLR4-/MyD88-/NF-κB-mediated inflammations in high fat diet-fed ApoE−/− mice.

These results indicated that rs2910164 may affect the susceptibility and severity of pediatric IgAN. Further studies are needed to validate these findings.