Protective effects of Bacillus probiotics against high-fat diet-induced metabolic disorders in mice

Abstract

Recently, modulation of gut microbiota by probiotics treatment has been emerged as a promising strategy for treatment of metabolic disorders. Apart from lactic acid bacteria, Bacillus species (Bacillus spp.) have also been paid attention as potential probiotics, but nevertheless, the molecular mechanisms for their protective effect against metabolic dysfunction remain to be elucidated. In this study, we demonstrate that a probiotic mixture composed of 5 different Bacillus spp. protects mice from high-fat diet (HFD)-induced obesity, insulin resistance and non-alcoholic fatty liver disease (NAFLD). Probiotic Bacillus treatment substantially attenuated body weight gain and enhanced glucose tolerance by sensitizing insulin action in skeletal muscle and epididymal adipose tissue (EAT) of HFD-fed mice. Bacillus-treated HFD-fed mice also exhibited significantly suppressed chronic inflammation in the liver, EAT and skeletal muscle, which was observed to be associated with reduced HFD-induced intestinal permeability and enhanced adiponectin production. Additionally, Bacillus treatment significantly reversed HFD-induced hepatic steatosis. In Bacillus-treated mice, hepatic expression of lipid oxidative genes was significantly increased, and lipid accumulation in subcutaneous and mesenteric adipose tissues were significantly decreased, commensurate with down-regulated expression of genes involved in lipid uptake and lipogenesis. Although, in Bacillus-treated mice, significant alterations in gut microbiota composition was not observed, the enhanced expression of tight junction-associated proteins showed a possibility of improving gut barrier function by Bacillus treatment. Our findings provide possible explanations how Bacillus probiotics protect diet-induced obese mice against metabolic disorders, identifying the treatment of probiotic Bacillus as a potential therapeutic approach.

Comprehensive amelioration of high-fat diet-induced metabolic dysfunctions through activation of the PGC-1α pathway by probiotics treatment in mice

“…Each group was fed with ND (10%kcal from fat, D12450J, Research Diets Inc., New Brunswick, NJ) or HFD (60%kcal from fat, D12492) for 1 week, and during following 12 weeks, mice received oral gavage with 100 μL PBS or a daily dose of probiotics (LGG or L. plantarum) with ND or HFD feeding. On the last day of the experiment, mice were sacrificed and tissue samples were harvested as previously described [22]. All animal experiments were performed in accordance with protocols approved by the Committee on the Ethics of Animal Experiments of the Handong Global University (Permit number: 20190424-009)…”

“…Sci., Yokohama, Japan) and HDL-cholesterol assay kit (Asan Pharm., Seoul, Korea), respectively. Triglycerides (TG) levels in the liver were quantified by the colorimetric assay as described previously [22]. Briefly, the liver was homogenized in chloroform/methanol (2:1) solution using a hand-held homogenizer (IKA, Stufen, Germany), and then incubated for 2 h at room temperature.…”

“…Tissue samples of the liver, quadriceps skeletal muscle, subcutaneous adipose tissues (SAT), mesenteric adipose tissue (MAT), and interscapular brown adipose tissue (BAT) were fixed, H&E stained and examined by light microscopy as described previously [22]. Briefly, 5-μmthick microtome sections of 10% v/v formalin/PBS-fixed, paraffin-embedded tissues were prepared, and stained with hematoxylin and eosin.…”

“…Total RNA extraction, reverse transcription and quantitative PCR were conducted as described previously [22]. Quantification of gene transcripts for cholesterol 7 alpha-hydroxylase (CYP7A1), CYP7B1, CYP27A1, CYP8B1, bile salt export pump (BSEP), β-klotho, fibroblast growth factor receptor 1c (FGFR1c), FGFR4, G protein-coupled bile acid receptor (TGR5), farnesoid X receptor (FXR), FGF15, HMG-CoA reductase (HMGCR), HMG-CoA synthase (HMGCS), scavenger receptor class B type 1 (SR-B1), ATP-binding cassette subfamily G member 5 (ABCG5), ABCG8, lecithin: cholesterol acyltransferase (LCAT), apolipoprotein A1 (ApoA1), liver X receptor α (LXRα), adiponectin, adiponectin receptor 1 (AdipoR1), AdipoR2, SIRT1, irisin, fibroblast growth factor 21 (FGF21), peroxisome proliferator-activated receptor α (PPARα), PPARγ coactivator 1α (PGC-1α), NADH-ubiquinone oxidoreductase chain 5 (ND5), Prdm16, Dio2, Cidea, Elov13, uncoupling protein 1 (UCP1), carnitine palmitoyltransferase 1 (CPT1), acyl-CoA oxidase 1 (ACOX1), and medium-chain acyl-coenzyme A dehydrogenase (MCAD), diacylglycerol acyltransferase 1 (DGAT1), DGAT2, PPARγ, sterolregulatory element binding protein 1c (SREBP1c), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), glycerol-3-phosphate acyltransferase (GPAT), stearoyl-CoA desaturase 1 (SCD1), acidic ribosomal phosphoprotein (Arbp), and β-actin was performed using gene-specific primers.…”

“…Western blot analysis was performed as described previously [22]. Antibodies against total AMPK (#2532, Cell signaling technology, Beverly, MA), phospho (Thr172) AMPK (#2531) were used as primary antibodies, followed by anti-rabbit IgG-HRP conjugated secondary antibody (#7074).…”