<i>Lactobacillus salivarius</i> AP-32 and <i>Lactobacillus reuteri</i> GL-104 decrease glycemic levels and attenuate diabetes-mediated liver and kidney injury in db/db mice

Abstract

Objectives Patients with type 2 diabetes mellitus (T2DM) exhibit strong insulin resistance or abnormal insulin production. Probiotics, which are beneficial live micro-organisms residing naturally in the intestinal tract, play indispensable roles in the regulation of host metabolism. However, the detailed mechanisms remain unclear. Here, we evaluate the mechanisms by which probiotic strains mediate glycemic regulation in the host. The findings should enable the development of a safe and natural treatment for patients with T2DM. Research designs and methods Sugar consumption by more than 20 strains of Lactobacillus species was first evaluated. The probiotic strains that exhibited high efficiency of sugar consumption were further coincubated with Caco-2 cells to evaluate the regulation of sugar absorption in gut epithelial cells. Finally, potential probiotic strains were selected and introduced into a T2DM animal model to study their therapeutic efficacy. Results Among the tested strains, Lactobacillus salivarius AP-32 and L. reuteri GL-104 had higher monosaccharide consumption rates and regulated the expression of monosaccharide transporters. Glucose transporter type-5 and Na + -coupled glucose transporter mRNAs were downregulated in Caco-2 cells after AP-32 and GL-104 treatment, resulting in the modulation of intestinal hexose uptake. Animal studies revealed that diabetic mice treated with AP-32, GL-104, or both showed significantly decreased fasting blood glucose levels, improved glucose tolerance and blood lipid profiles, and attenuated diabetes-mediated liver and kidney injury. Conclusion Our data elucidate a novel role for probiotics in glycemic regulation in the host. L. salivarius AP-32 and L. reuteri GL-104 directly reduce monosaccharide transporter expression in gut cells and have potential as therapeutic probiotics for patients with T2DM.