Mechanisms of cholesterol-lowering effects of dietary insoluble fibres: relationships with intestinal and hepatic cholesterol parameters.

Fibres with a range of abilities to perturb cholesterol homeostasis were used to investigate how the serum cholesterol-lowering effects of insoluble dietary fibres are related to parameters of intestinal cholesterol absorption and hepatic cholesterol homeostasis in mice. Cholestyramine, chitosan and cellulose were used as examples of fibres with high, intermediate and low bile acid-binding capacities, respectively. The serum cholesterol levels in a control group of mice fed a high fat/high cholesterol (HFHC) diet for 3 weeks increased about 2-fold to 4.

Inhibition of the transforming growth factor beta (TGFbeta) pathway by interleukin-1beta is mediated through TGFbeta-activated kinase 1 phosphorylation of SMAD3.

Transforming growth factor beta is the prototype of a large family of secreted factors that regulate multiple biological processes. In the immune system, TGFbeta acts as an anti-inflammatory and immunosuppressive molecule, whereas the cytokine interleukin (IL)-1beta is a crucial mediator of inflammatory responses and induces proinflammatory genes and acute phase proteins. Here, we present evidence for the existence of a direct inhibitory interaction between the IL-1beta and TGFbeta signaling cascades that is not dependent on IL-1beta-induced SMAD7 expression.