Dataset Information

Hepatic JAK2 protects against atherosclerosis through circulating IGF-1.

ABSTRACT: Atherosclerosis is considered both a metabolic and inflammatory disease; however, the specific tissue and signaling molecules that instigate and propagate this disease remain unclear. The liver is a central site of inflammation and lipid metabolism that is critical for atherosclerosis, and JAK2 is a key mediator of inflammation and, more recently, of hepatic lipid metabolism. However, precise effects of hepatic Jak2 on atherosclerosis remain unknown. We show here that hepatic Jak2 deficiency in atherosclerosis-prone mouse models exhibited accelerated atherosclerosis with increased plaque macrophages and decreased plaque smooth muscle cell content. JAK2's essential role in growth hormone signalling in liver that resulted in reduced IGF-1 with hepatic Jak2 deficiency played a causal role in exacerbating atherosclerosis. As such, restoring IGF-1 either pharmacologically or genetically attenuated atherosclerotic burden. Together, our data show hepatic Jak2 to play a protective role in atherogenesis through actions mediated by circulating IGF-1 and, to our knowledge, provide a novel liver-centric mechanism in atheroprotection.

SUBMITTER: Sivasubramaniyam T

PROVIDER: S-EPMC5518558 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Hepatic JAK2 protects against atherosclerosis through circulating IGF-1.

Sivasubramaniyam Tharini T Schroer Stephanie A SA Li Angela A Luk Cynthia T CT Shi Sally Yu SY Besla Rickvinder R Dodington David W DW Metherel Adam H AH Kitson Alex P AP Brunt Jara J JJ Lopes Joshua J Wagner Kay-Uwe KU Bazinet Richard P RP Bendeck Michelle P MP Robbins Clinton S CS Woo Minna M

JCI insight 20170720 14

Atherosclerosis is considered both a metabolic and inflammatory disease; however, the specific tissue and signaling molecules that instigate and propagate this disease remain unclear. The liver is a central site of inflammation and lipid metabolism that is critical for atherosclerosis, and JAK2 is a key mediator of inflammation and, more recently, of hepatic lipid metabolism. However, precise effects of hepatic Jak2 on atherosclerosis remain unknown. We show here that hepatic Jak2 deficiency in ...[more]

PMID: 28724798

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Project description:Objective- Inflammatory stimuli enhance the progression of atherosclerotic disease. Inflammation also increases the expression of hepcidin, a hormonal regulator of iron homeostasis, which decreases intestinal iron absorption, reduces serum iron levels and traps iron within macrophages. The role of macrophage iron in the development of atherosclerosis remains incompletely understood. The objective of this study was to investigate the effects of hepcidin deficiency and decreased macrophage iron on the development of atherosclerosis. Approach and Results- Hepcidin- and LDL (low-density lipoprotein) receptor-deficient ( Hamp-/-/ Ldlr-/-) mice and Hamp+/+/ Ldlr-/- control mice were fed a high-fat diet for 21 weeks. Compared with control mice, Hamp-/-/ Ldlr-/- mice had decreased aortic macrophage activity and atherosclerosis. Because hepcidin deficiency is associated with both increased serum iron and decreased macrophage iron, the possibility that increased serum iron was responsible for decreased atherosclerosis in Hamp-/-/ Ldlr-/- mice was considered. Hamp+/+/ Ldlr-/- mice were treated with iron dextran so as to produce a 2-fold increase in serum iron. Increased serum iron did not decrease atherosclerosis in Hamp+/+/ Ldlr-/- mice. Aortic macrophages from Hamp-/-/ Ldlr-/- mice had less labile free iron and exhibited a reduced proinflammatory (M1) phenotype compared with macrophages from Hamp+/+/ Ldlr-/- mice. THP1 human macrophages treated with an iron chelator were used to model hepcidin deficiency in vitro. Treatment with an iron chelator reduced LPS (lipopolysaccharide)-induced M1 phenotypic expression and decreased uptake of oxidized LDL. Conclusions- In summary, in a hyperlipidemic mouse model, hepcidin deficiency was associated with decreased macrophage iron, a reduced aortic macrophage inflammatory phenotype and protection from atherosclerosis. The results indicate that decreasing hepcidin activity, with the resulting decrease in macrophage iron, may prove to be a novel strategy for the treatment of atherosclerosis.

Dataset Information

Hepatic JAK2 protects against atherosclerosis through circulating IGF-1.

Publications

Hepatic JAK2 protects against atherosclerosis through circulating IGF-1.

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