Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria. It is found from intestinal microbes in the circulatory system and considered a trigger factor for low-grade inflammation in obesity. High-fat diet intake and its related obesity can cause gut microbiota disorder, leading to increased gut permeability, paracellular absorption and transcellular transport of endogenous endotoxin in the cardiovascular system. High-fat diet intake can also increase plasma LPS levels, and causing chronic or “low-grade” inflammation. In this review article, we summarize the recent research advancements on the mechanism of low-grade inflammation and its related obesity. We also propose several approaches that can be used to reduce endogenous endotoxin absorption. Supplemental data for this article is available online at https://doi.org/10.1080/08830185.2021.1996573 . GRAPHICAL ABSTRACT

Kefir consists of a large number of probiotics, which can regulate or shape the balance of intestinal microbiota, and enhance the host's immune response. Kefir microbiota can shape the mucosal immunity of the body through SCFAs, EPS, polypeptides, lactic acid, and other metabolites and microbial antigens themselves, and this shaping may have time windows and specific pathways. Kefir can regulate antibody SIgA and IL-10 levels to maintain intestinal homeostasis, and its secreted SIgA can shape the stable microbiota system by wrapping and binding different classes of microorganisms. The incidence of intestinal inflammation is closely linked to the development and maturation of intestinal mucosal immunity. Based on summarizing the existing research results on Kefir, its metabolites, and immune system development, this paper proposes to use Kefir, traditional fermented food with natural immune-enhancing components and stable functional microbiota, as an intervention method. Early intervention in the immune system may seize the critical window period of mucosal immunity and stimulate the development and maturation of intestinal mucosal immunity in time.

This study investigated the effects of dietary supplementation with Bacillus amyloliquefaciens D1 (B. amyloliquefaciens D1) on growth performance, serum anti-inflammatory cytokines, and intestinal microbiota composition and diversity in bearded chickens. To investigate the effects of Bacillus amyloliquefaciensa and fermented soy milk, 7-day-old broilers were orally fed different doses of Bacillus amyloliquefaciens D1 fermented soy milk for 35 days, with the unfermented soy milk group as the Placebo group. This study found that B. amyloliquefaciens D1 fermented soy milk improved the intestinal microbiota of broilers, significantly increasing the abundance of beneficial bacteria and decreasing the abundance of harmful bacteria in the gut. B. amyloliquefaciens D1 fermented soy milk also significantly reduced the serum lipopolysaccharide (LPS) content. The body weight and daily weight gain of broilers were increased. In conclusion, the results of this study are promising and indicate that supplementing the diets of bearded chickens with B. amyloliquefaciens D1 fermented soy milk has many beneficial effects in terms of maintaining intestinal microbiota balance and reducing inflammation in chickens.