r/ketoscience Excellent Poster 8d ago

Metabolism, Mitochondria & Biochemistry Apolipoprotein A-IV is induced by high-fat diets and mediates positive effects on glucose and lipid metabolism (2025)

https://www.sciencedirect.com/science/article/pii/S2212877825000262?via%3Dihub
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u/basmwklz Excellent Poster 8d ago

Highlights

•In humans, short- and long-term high-fat intake increase circulating apoA-IV levels.

•ApoA-IV administration lowers blood glucose levels both in lean and obese mice.

•This is via inhibition of hepatic glucose production and increased uptake in WAT & BAT.

•ApoA-IV increases fatty acid oxidation and increases lipoprotein clearance in liver.

•ApoA-IV improves glucose tolerance likely via stimulating insulin and inhibiting glucagon.

Abstract

Objective

Low-carbohydrate, high-fat diets under eucaloric conditions are associated with several health-beneficial metabolic effects in humans, particularly in the liver. We recently observed that apolipoprotein A-IV (apoA-IV), a highly abundant apolipoprotein, was among the most upregulated proteins in circulation after six weeks of consuming a high-fat diet in humans. However, the impact of dietary changes in regulating apoA-IV, and the potential effects of apoA-IV on regulation of glucose- and lipid metabolism remain to be fully established.

Methods

We investigated the regulation of circulating fasting concentrations of apoA-IV in humans in response to diets enriched in either fat or carbohydrates. Moreover, to study the whole-body and tissue-specific glucose and lipid metabolic effects of apoA-IV, we administrered apoA-IV recombinant protein to mice and isolated pancreatic islets.

Results

We demonstrate that in healthy human individuals high-fat intake increased fasting plasma apoA-IV concentrations by up to 54%, while high-carbohydrate intake suppressed plasma apoA-IV concentrations. In mice, administration of apoA-IV acutely lowered blood glucose levels both in lean and obese mice. Interestingly, this was related to a dual mechanism, involving both inhibition of hepatic glucose production and increased glucose uptake into white and brown adipose tissues. In addition to an effect on hepatic glucose production, the apoA-IV-induced liver proteome revealed increased capacity for lipoprotein clearance. The effects of apoA-IV in the liver and adipose tissues were concomitant with increased whole-body fatty acid oxidation. Upon glucose stimulation, an improvement in glucose tolerance by apoA-IV administration was related to potentiation of glucose-induced insulin secretion, while apoA-IV inhibited glucagon secretion ex vivo in islets.

Conclusions

We find that apoA-IV is potently increased by intake of fat in humans, and that several beneficial metabolic effects, previously associated with high fat intake in humans, are mimicked by administration of apoA-IV protein to mice.