Session: 733 APS Inflammation, Oxidative Stress and Metabolism in Health and Disease Poster Session
(733.6) Neutrophil Extracellular Traps Contribute to Perivascular Adipose Tissue Dysfunction in High-Fat Diet Obese Mice
Monday, April 4, 2022
10:15 AM – 12:15 PM
Location: Exhibit/Poster Hall A-B - Pennsylvania Convention Center
Poster Board Number: E273
Rafael Costa (University of Sao Paulo), Karla Neves (University of Glasgow), Rhéure Lopes (University of Glasgow), Juliano Alves (University of Sao Paulo), Aline Fedoce (University of Sao Paulo), Josiane Silva (University of Sao Paulo), Daniel Rodrigues (University of Sao Paulo), Douglas Prado (University of Sao Paulo), Ayda Schnaider (University of Sao Paulo), Fernando Cunha (University of Sao Paulo), José Carlos Alves (University of Sao Paulo), Rita Tostes (University of Sao Paulo)
Background: Obesity triggers functional changes in the perivascular adipose tissue (PVAT), favoring the release of vasoconstrictor factors and the activation of contractile mechanisms in vascular smooth muscle cells. In the PVAT of obese individuals, there is infiltration of immune cells, including neutrophils. A neutrophil defense mechanism is the formation of neutrophil extracellular traps (NETs), a cytotoxic framework that allows maintenance and expansion of inflammatory processes. We hypothesize that PVAT dysfunction in obese mice is due to increased neutrophil infiltration, NETs formation and inflammation.
Methods: Six weeks-old male Balb/C mice received control (CD) or high fat diet (HFD) for 18 weeks. Vascular function was assessed in endothelium-intact mesenteric arteries in the presence or absence of PVAT. Mice were treated with DNAse type 1 (10 mg/kg for 14 days, every other day). Molecular mechanisms were investigated. Experiments were approved by the Ethics Committee on Animal Research of the Ribeirao Preto Medical School, University of Sao Paulo (protocol nº 209/2016)
Results: Values are expressed relatively to the contraction triggered by 120 mM KCl [Emax (% KCl)]. In Balb/C mice, the PVAT decreased the contractile response in control arteries [Control PVAT (-): 123.2±8.1 n=6; Control PVAT (+): 64.4±4.0 n=6]. However, HFD promoted partial loss of PVAT anti-contractile effect [HFD PVAT (-): 127.9±6.9 n=6; HFD PVAT (+): 98.3±7.4 n=6]. In PVAT of obese mice there was a greater amount of neutrophils, compared to PVAT from control mice [Control: 8.0% n=5; HFD: 18.9% n=5]. In PVAT of obese mice there was greater formation of NETs, and production of interleukin 6 (IL-6), compared to PVAT from control mice [NETs in pg/ml – Control: 30.5±2.7 n=6; HFD: 71.4±3.2 n=6; IL-6 in pg/100 mg of PVAT – Control: 45.6±1.9 n=6; HFD: 98.4±3.1 n=6]. DNAse treatment reduced the formation of NETs and IL-6 in the PVAT of obese mice [NETs in pg/ml – HFD+DNAse: 18.3±1.2 n=6; IL-6 in pg/100 mg of PVAT – HFD: 48.1±3.4 n=6]. DNAse treatment restored PVAT anticontractile function in obese mice [HFD+DNAse PVAT (+): 71.3±7.4 n=6]. Adipose tissue of obese humans exhibited greater formation of NETs and production of IL-6 compared to adipose tissue of eutrophic humans [NETs in pg/ml – Eutrophic: 20.5±3.7 n=7; Obese: 79.2±1.3 n=7; IL-6 in pg/100 mg of adipose tissue – Eutrophic: 9.7±2.9 n=7; Obese: 27.7±2.6 n=7].
Conclusion: These results indicate that, in obesity, there is a greater neutrophils infiltration in the PVAT and, consequently, greater formation of NETs and inflammation, events that contribute to PVAT dysfunction.
