Loss of VEGFB Accelerates Atherosclerosis in Mouse via inhibiting White Adipose Tissues Browning

This study aimed to investigate the mechanism by which VEGFB regulates mitochondrial function and lipid metabolism, thereby alleviating the progression of atherosclerosis, to provide a theoretical basis for its prevention and treatment. Analysis of public databases revealed high expression of VEGFB in atherosclerotic adipose tissue. Experimental results demonstrated that: 1) VEGFB deficiency significantly increased body weight and adipose weight in mice (P<0.05). H&E staining and UCP1 protein detection confirmed that VEGFB knockdown suppressed white adipose tissue browning. Metabolic cage assays and lipid level measurements indicated that VEGFB deficiency caused lipid metabolism disorders and significantly promoted lipid accumulation (P<0.05). 2) Whole-mount staining showed that VEGFB knockdown did not affect adipose vascular density. However, mitochondrial transmission electron microscopy revealed structural abnormalities. Adipose ATP content assays, primary cell immunofluorescence, and flow cytometry confirmed that VEGFB autonomously regulates mitochondrial biogenesis and function, which was significantly impaired in adipocytes upon VEGFB knockdown (P<0.05). 3) In ApoE-/- and Vegfb-/-/ApoE-/- double knockout mouse models, serum lipid level analysis, hepatic H&E staining, and oil red O staining demonstrated that VEGFB deficiency caused significant systemic lipid accumulation (P<0.05). Aortic oil red O and H&E staining revealed that VEGFB deficiency significantly exacerbated atherosclerotic progression under both normal and high-fat diets (P<0.05). 4) RNA-seq analysis identified adipose Dio2 as a key gene mediating VEGFB's regulation of mitochondrial biogenesis and function. qRT-PCR and Western Blot validation showed that the expression of Dio2, Ucp1, and mitochondrial-related genes (Tfam, Ndufa9, ATP6, Cox1, *MT-ND4*) and proteins were all significantly downregulated in VEGFB-deficient adipose tissue (P<0.05). Database correlation analysis verified that DIO2 regulates the expression of mitochondria-related genes through UCP1.