Role of Modified Diet and Gut Microbiota in Metabolic Endotoxemia in Mice

Abstract This study was aimed to investigate the effect of cultured gut microbiota (GM) from obese humans coupled HFD in inducing metabolic endotoxemia in humanized mice. In total, 30 strains were isolated from 10 stool samples of obese patients. Following morphological and biochemical characterization, 16S rRNA gene sequencing of six abundant isolates identified these as Klebsiella aerogenes, Levilactobacillus brevis, Escherichia coli, Staphylococcus aureus, Bacillus cereus and Bacillus subtilis (MZ052089- MZ052094). In vivo trial using above six isolates, known as human gut microbiota (HGM), was performed for six months. Sixteen mice were distributed into four groups i.e., G1 (control) mice fed with chow diet, group 2 (G2) mice with HFD, group 3 (G3) mice with HFD + HGM and group 4 (G4) mice with chow diet + HGM. Body mass index (BMI) and plasma endotoxins were measured pre and post experiment. In vivo study revealed that HFD + HGM caused significant increase (3.9 g/cm at 20 weeks) in the body weight and BMI (0.4g/cm post experiment) of G3 mice compared to the other groups. One way ANOVA showed significantly higher level of endotoxins (2.41, 4.08 and 3.7 mmol/l) in mice groups G2, G3 and G4, respectively, indicating onset of metabolic endotoxemia. Cecal contents of experimental mice groups showed more diversified microbiota in mice groups G1 and G4 compared to G2 and G3 where high fat feeding alone and combined with obese gut microbiota caused a shift in microbial diversity as observed by all five strains belonging to either Firmicutes or Bacteriodetes phyla, respectively. In conclusion, current study reported that minor alteration in GM composition through HFD feeding and cultured GM transfer has significant impact in development of metabolic endotoxemia, possibly via modified intestinal permeability.