Chronic Copper Overload Triggers Inflammation in Mesenteric PVAT Alongside Changes in Renin-Angiotensin...

Background/Objectives: Copper is an essential micronutrient required for physiological functions, but elevated serum levels impair vascular reactivity and blood pressure regulation. Given PVAT's critical role in vascular function, this study aimed to investigate the effects of chronic copper overload on the secretory function of mesenteric PVAT, focusing on its vasoregulatory role. Methods: In the first phase, 8-week-old male Wistar rats were assigned to two groups, namely control (saline, i.p.) or copper (25.72 µg/kg/day Cu, i.p., for 30 days), corresponding to twice the recommended daily dose of copper. In the second phase, rats were divided into four groups: control (saline, i.p., water by gavage), copper (Cu, i.p., water by gavage), losartan (saline, i.p., 10 mg/kg/day losartan by gavage), or copper + losartan (Cu, i.p., 10 mg/kg/day losartan by gavage). After euthanasia, mesenteric PVAT was collected for morphometric analysis, gene and protein expression of adipokines, inflammatory molecules, and the renin-angiotensin system. Serum was used for hormone and biochemical measurements. Results: In mesenteric PVAT, chronic copper overload increased adipocyte diameter and reduced lipolysis. It also elevated the secretion of TNF-α and PAI-1 while decreasing IL-10 levels. Additionally, it upregulated the mRNA expression of MCP-1, F4/80, CD86, TLR4, arginase-1, iNOS, ACE1, and AT1R, alongside an increase in serum angiotensin II levels. When copper treatment was combined with losartan, an AT1R antagonist, adipocyte hypertrophy; TNF-α secretion; and the gene expression of TLR4, F4/80, and arginase-1 were attenuated. Conclusions: Chronic exposure to double the recommended dose of Cu disrupts the secretory function of mesenteric PVAT, promoting inflammation and altering the local RAS. These effects appear to occur, at least in part, alongside the activation of the AT1R-TLR4-angiotensin II signaling pathway, triggering the upregulation of vasoregulatory inflammatory markers.