Screening and identification of intestinal lipid-lowering probiotics and their effect on regulating lipid metabolism in C57BL/6J mice

Abstract

Recent research shows intestinal microbiota is closely related to the host lipid metabolism. Discovering new lipid-lowering probiotic strains is important for effectively preventing obesity. In this study, five probiotic strains were identified among 108 strains screened from the fecal samples of healthy individuals (18.5 kg/m² ≤ BMI < 24 kg/m²), with Limosilactobacillus reuteri (L. r) and Limosilactobacillus balticus (L. b) exhibiting the most promising lipid-lowering functionalities. Supplementing L. r and L. b delayed weight gain, adipose tissue, hepatic lipid accumulation and mitigated oxidative stress disturbances induced by the High-fat Diet (HFD) in C57BL/6 J mice. L. b-L significantly reduced the expression levels of pro-inflammatory cytokines IL-1β and IL-6 by 43.67 % and 46.96 % compared to the HFD group. L. r and L. b reduced the mRNA expression levels of LDLR and SREBP1, which are involved in TC production and metabolism, down-regulated DGAT1 and LXR to reduce TG accumulation induced by HFD, and up-regulated the expression levels of SHP and FXR to limit intestinal cholesterol absorption. L. r-L and L. b-L had lower SHP expression by 58.33 % and 52.66 % than the HFD group. Furthermore, supplementation with L. r and L. b reduced the relative abundance of Erysipelotrichaceae and Ruminococcaceae and increased Lactobacillzceze. These changes were accompanied by elevated key metabolites such as n-valeric and isovaleric acid, associated with HFD-induced obesity. In conclusion, these findings underscore the potential of L. r and L. b in mitigating obesity by modulating intestinal environmental homeostasis, lipid metabolism, inflammatory responses, and gut microbiota composition.

Keywords: Antioxidant activity; Bile saline hydrolysate; Cholesterol esterase; In vitro screening; Intestinal microbiota; Probiotics.