[HTML][HTML] Modulation of gut microbiota by antibiotics improves insulin signalling in high-fat fed mice

BM Carvalho, D Guadagnini, DML Tsukumo… - Diabetologia, 2012 - Springer
BM Carvalho, D Guadagnini, DML Tsukumo, AA Schenka, P Latuf-Filho, J Vassallo, JC Dias…
Diabetologia, 2012Springer
Aims/hypothesis A high-fat dietary intake induces obesity and subclinical inflammation,
which play important roles in insulin resistance. Recent studies have suggested that
increased concentrations of circulating lipopolysaccharide (LPS), promoted by changes in
intestinal permeability, may have a pivotal role in insulin resistance. Thus, we investigated
the effect of gut microbiota modulation on insulin resistance and macrophage infiltration.
Methods Swiss mice were submitted to a high-fat diet with antibiotics or pair-feeding for 8 …
Aims/hypothesis
A high-fat dietary intake induces obesity and subclinical inflammation, which play important roles in insulin resistance. Recent studies have suggested that increased concentrations of circulating lipopolysaccharide (LPS), promoted by changes in intestinal permeability, may have a pivotal role in insulin resistance. Thus, we investigated the effect of gut microbiota modulation on insulin resistance and macrophage infiltration.
Methods
Swiss mice were submitted to a high-fat diet with antibiotics or pair-feeding for 8 weeks. Metagenome analyses were performed on DNA samples from mouse faeces. Blood was collected to determine levels of glucose, insulin, LPS, cytokines and acetate. Liver, muscle and adipose tissue proteins were analysed by western blotting. In addition, liver and adipose tissue were analysed, blinded, using histology and immunohistochemistry.
Results
Antibiotic treatment greatly modified the gut microbiota, reducing levels of Bacteroidetes and Firmicutes, overall bacterial count and circulating LPS levels. This modulation reduced levels of fasting glucose, insulin, TNF-α and IL-6; reduced activation of toll-like receptor 4 (TLR4), c-Jun N-terminal kinase (JNK), inhibitor of κ light polypeptide gene enhancer in B cells, kinase β (IKKβ) and phosphorylated IRS-1 Ser307; and consequently improved glucose tolerance and insulin tolerance and action in metabolically active tissues. In addition, there was an increase in portal levels of circulating acetate, which probably contributed to an increase in 5′-AMP-activated protein kinase (AMPK) phosphorylation in mice. We observed a striking reduction in crown-like structures (CLS) and F4/80+ macrophage cells in the adipose tissue of antibiotic-treated mice.
Conclusions/interpretation
These results suggest that modulation of gut microbiota in obesity can improve insulin signalling and glucose tolerance by reducing circulating LPS levels and inflammatory signalling. Modulation also appears to increase levels of circulating acetate, which activates AMPK and finally leads to reduced macrophage infiltration.
Springer