Brown Adipocyte BMAL1 Deficiency Is Associated with PVAT Remodeling and Increased Atherosclerosis

Perivascular adipose tissue (PVAT) is increasingly recognized as an active vascular regulator that influences inflammation, metabolism, and atherosclerotic progression. In healthy vessels, PVAT displays brown adipose-like features and contributes to vascular protection, whereas PVAT dysfunction is associated with adipose whitening, inflammatory activation, and enhanced plaque formation. Circadian clock genes are major regulators of tissue metabolism, yet their role in PVAT biology and atherosclerosis remains incompletely understood. Here, we investigated the function of the core circadian factor BMAL1 in brown adipocytes and PVAT using a brown adipocyte-specific BMAL1 knockout model (Bmal1^BAKO) and ApoE-deficient atherosclerosis-prone mice. Transcriptomic profiling of thoracic aortic PVAT and abdominal aortic PVAT revealed that BMAL1 deficiency induces a shift in metabolic gene expression profiles characterized by upregulation of glycolytic and lipogenic gene programs, together with suppression of genes linked to thermogenic and vascular homeostasis. Mechanistically, BMAL1 loss increased Mlxipl (encoding ChREBP) expression, and ChREBP knockdown attenuated the glycolytic-lipogenic transcriptional response to BMAL1 depletion in cultured brown adipocytes. In parallel, BMAL1-deficient PVAT exhibited enlarged lipid droplets, increased oxidative stress-related transcriptional profile, and inflammatory remodeling accompanied by macrophage accumulation. In ApoE^-/- mice, brown adipocyte-specific BMAL1 deletion aggravated atherosclerotic lesion formation in both chow-fed aging mice and Western diet-fed young mice, without major changes in systemic energy balance. In conclusion, brown adipocyte BMAL1 deficiency was associated with ChREBP-linked metabolic reprogramming, loss of brown-like PVAT features, oxidative and macrophage-associated remodeling, and increased atherosclerosis.