# Global knockout of VEGFB improves lipoprotein lipase activity leading to an improved lipid profile during diabetes

## TL;DR

Removing VEGFB in rats improves heart lipid metabolism and protects against diabetic heart disease.

## Contribution

This study reveals that VEGFB knockout improves cardiac lipid metabolism and protects against diabetic cardiomyopathy in diabetic rats.

## Key findings

- Global Vegfb knockout in rats increased cardiac LPL activity and reduced plasma saturated fatty acids in diabetes.
- VEGFB inhibition protected against diabetic cardiomyopathy by reducing FA oxidation and preserving heart function.
- VEGFB knockout limited cardiac lipid accumulation and improved metabolic flexibility in diabetic rats.

## Abstract

Diabetes affects over half a billion people worldwide, with cardiovascular disease being its leading cause of death, either occurring secondary to atherosclerosis or due to an intrinsic defect in heart muscle (diabetic cardiomyopathy, DbCM). One instigator for DbCM is impaired cardiac metabolism characterized by excessive fatty acid (FA) delivery and utilization by the heart, causing oxidative stress and toxic lipid accumulation. Inhibition of vascular endothelial growth factor B (VEGFB) has been shown to counter these factors associated with abnormal cardiac metabolism by inducing metabolic flexibility and preventing cardiac lipid accumulation in Type 2 diabetes. However, its impact on lipoprotein lipase (LPL) and the sources of FA for cardiac use in Type 1 diabetes is unknown. Global Vegfb knockout (VegfbKO) in rats caused limited phenotype and cardiac transcriptome changes under normal conditions but notably reduced cardiac LPL activity, probably by impeding LPL translocation from cardiomyocyte to the coronary vasculature. Under streptozotocin (STZ)-induced diabetes, VegfbKO rats exhibited increased cardiac LPL activity, protecting animals from dyslipidemia, decreased plasma saturated FA, and provided a safer cardiac FA source, LPL-derived FA. Knockout of Vegfb also protected animals from DbCM by inhibiting excess FA oxidation, preserving angiogenesis and alleviating cell death in the heart. Inhibiting VEGFB may offer a promising therapeutic approach to address the current lack of mechanism-based treatments for DbCM.