IL6 and obesity due to melanocortin 4 receptor deficiency: This HFD mouse model has about 60% more blood cholesterol and higher pro-inflammatory cytokines (about 10-fold higher TNF-α and 3-fold higher IL-6) compared to the ND mouse model (Figures 5, 6), indicating that the HFD mouse model is suitable for in vivo evaluation of cholesterol reduction and immune regulation from obesity by bifidobacteria in this study.