Skip to main content
. Author manuscript; available in PMC: 2017 Dec 1.
Published in final edited form as: Trends Endocrinol Metab. 2016 Sep 10;27(12):831–843. doi: 10.1016/j.tem.2016.08.003

Figure 1. The microbiota affects metabolic syndrome via the immune system.

Figure 1

a) Obesity is associated with an increase in Firmicutes and a decrease in Bacteroidetes. Firmicutes provide an increased amount of calories to the host by increased harvest of energy from the diet. b) Outgrowth of Proteobacteria is associated with metabolic syndrome and has been shown to increase the frequency of IFNγ-producing T cells in the host, which in turn is associated with increased concentrations of serum LPS. Serum LPS and IFNγ may then drive the development of pro-inflammatory M1 macrophages in the adipose tissue. M1 macrophages express significantly higher amounts of TNFα and IL-1β than the resident M2 macrophages of the gut, and both cytokines contribute to insulin resistance. Beige adipose cells further contribute to health by metabolizing lipids to heat instead of storing them and are supported directly and indirectly by the cytokines IL-4, IL-13, IL-25 and IL-33. c) Mucophilic bacteria Akkermansia combat many of the effects of Proteobacteria outgrowth, including IFNγ production, and can alleviate symptoms associated with metabolic syndrome in animal models.