scholarly journals Deleting myeloid IL-10 receptor signalling attenuates atherosclerosis in LDLR-/- mice by altering intestinal cholesterol fluxes

2016 ◽  
Vol 116 (09) ◽  
pp. 565-577 ◽  
Author(s):  
Gemma Brufau ◽  
Marion J. J. Gijbels ◽  
Ine M. J. Wolfs ◽  
Saskia van der Velden ◽  
Chantal C. H. Pöttgens ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Homeostasis ◽  
Liver Cholesterol ◽  
Specific Cell ◽  
Low Density ◽  
Atherosclerosis Development ◽  
Deficient Mice

SummaryInflammatory responses and cholesterol homeostasis are interconnected in atherogenesis. Interleukin (IL)-10 is an important anti-inflammatory cytokine, known to suppress atherosclerosis development. However, the specific cell types responsible for the atheroprotective effects of IL-10 remain to be defined and knowledge on the actions of IL-10 in cholesterol homeostasis is scarce. Here we investigated the functional involvement of myeloid IL-10-mediated atheroprotection. To do so, bone marrow from IL-10 receptor 1 (IL-10R1) wild-type and myeloid IL-10R1-deficient mice was transplanted to lethally irradiated female LDLR-/- mice. Hereafter, mice were given a high cholesterol diet for 10 weeks after which atherosclerosis development and cholesterol metabolism were investigated. In vitro, myeloid IL-10R1 deficiency resulted in a pro-inflammatory macrophage phenotype. However, in vivo significantly reduced lesion size and severity was observed. This phenotype was associated with lower myeloid cell accumulation and more apoptosis in the lesions. Additionally, a profound reduction in plasma and liver cholesterol was observed upon myeloid IL-10R1 deficiency, which was reflected in plaque lipid content. This decreased hypercholesterolaemia was associated with lowered very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels, likely as a response to decreased intestinal cholesterol absorption. In addition, IL-10R1 deficient mice demonstrated substantially higher faecal sterol loss caused by increased non-biliary cholesterol efflux. The induction of this process was linked to impaired ACAT2-mediated esterification of liver and plasma cholesterol. Overall, myeloid cells do not contribute to IL-10-mediated atheroprotection. In addition, this study demonstrates a novel connection between IL-10-mediated inflammation and cholesterol homeostasis in atherosclerosis. These findings make us reconsider IL-10 as a beneficial influence on atherosclerosis.Supplementary Material to this article is available online at www.thrombosis-online.com.

scholarly journals The Biological Function of Sigma-2 Receptor/TMEM97 and Its Utility in PET Imaging Studies in Cancer

Cancers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1877
Author(s):  
Chenbo Zeng ◽  
Aladdin Riad ◽  
Robert H. Mach
Keyword(s):  
Pet Imaging ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Therapy Response ◽  
Cholesterol Homeostasis ◽  
Imaging Biomarker ◽  
Low Density ◽  
Density Lipoprotein Receptor ◽  
Ldl Uptake

The sigma-2 receptor was originally defined pharmacologically and recently identified as TMEM97. TMEM97 has been validated as a biomarker of proliferative status and the radioligand of TMEM97, [18F]ISO-1, has been developed and validated as a PET imaging biomarker of proliferative status of tumors and as a predictor of the cancer therapy response. [18F]ISO-1 PET imaging should be useful to guide treatment for cancer patients. TMEM97 is a membrane-bound protein and localizes in multiple subcellular organelles including endoplasmic reticulum and lysosomes. TMEM97 plays distinct roles in cancer. It is reported that TMEM97 is upregulated in some tumors but downregulated in other tumors and it is required for cell proliferation in certain tumor cells. TMEM97 plays important roles in cholesterol homeostasis. TMEM97 expression is regulated by cholesterol-regulating signals such as sterol depletion and SREBP expression levels. TMEM97 regulates cholesterol trafficking processes such as low density lipoprotein (LDL) uptake by forming complexes with PGRMC1 and low density lipoprotein receptor (LDLR), as well as cholesterol transport out of lysosome by interacting with and regulating NPC1 protein. Understanding molecular functions of TMEM97 in proliferation and cholesterol metabolism will be important to develop strategies to diagnose and treat cancer and cholesterol disorders using a rich collection of TMEM97 radiotracers and ligands.

A potent soluble epoxide hydrolase inhibitor, t-AUCB, modulates cholesterol balance and oxidized low density lipoprotein metabolism in adipocytes in vitro

2014 ◽  
Vol 395 (4) ◽  
pp. 443-451 ◽  
Author(s):  
Li Shen ◽  
Hongchun Peng ◽  
Shuiping Zhao ◽  
Danyan Xu
Keyword(s):  
Cholesterol Efflux ◽  
Epoxide Hydrolase ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Soluble Epoxide Hydrolase ◽  
Cholesterol Homeostasis ◽  
Low Density ◽  
Oxidized Low Density Lipoprotein

Abstract The cholesterol metabolism in adipose tissue is dependent on the balance between cholesterol uptake and efflux. Adipocytes dysfunction and its cholesterol imbalance are associated with obesity. Adipocytes are the site for clearance of oxidized low density lipoprotein (oxLDL) in blood. Soluble epoxide hydrolase (sEH) is highly expressed in adipocytes. sEH converts epoxyeicosatrienoic acids (EETs) into less bioactive dihydroxyeicosatrienoic acids, which regulate cholesterol metabolism in adipocytes and block the development of atherosclerosis. In vitro, 3T3-L1 differentiated adipocytes were incubated with the sEH inhibitor t-AUCB (0, 1, 10, 50 or 100 mmol/l) for 24 h with or without the PPARγ inhibitor GW9662. To determine the effect of t-AUCB on oxLDL endocytosis, degradation and cholesterol efflux from adipocytes, we demonstrated that t-AUCB enhances the CD36-mediated recognition and degradation of oxLDL and improves cholesterol efflux via the upregulation of ABCA1 expression. Furthermore, t-AUCB blocked TNF-α secretion and increased adiponectin levels found in adipocytes culture medium. We provide evidence that these effects are PPARγ-dependent. These results suggest that an increase in EETs because of sEH inhibition could maintain cellular cholesterol homeostasis by the regulation of oxLDL clearance and cholesterol efflux via the EETs–PPARγ pathway.

scholarly journals Macrophage LRP1 Promotes Diet-Induced Hepatic Inflammation and Metabolic Dysfunction by Modulating Wnt Signaling

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Dianaly T. Au ◽  
Mary Migliorini ◽  
Dudley K. Strickland ◽  
Selen C. Muratoglu
Keyword(s):  
Insulin Resistance ◽  
Wnt Signaling ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Hepatic Inflammation ◽  
Low Density Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

Hepatic inflammation is associated with the development of insulin resistance, which can perpetuate the disease state and may increase the risk of metabolic syndrome and diabetes. Despite recent advances, mechanisms linking hepatic inflammation and insulin resistance are still unclear. The low-density lipoprotein receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is highly expressed in macrophages, adipocytes, hepatocytes, and vascular smooth muscle cells. To investigate the potential role of macrophage LRP1 in hepatic inflammation and insulin resistance, we conducted experiments using macrophage-specific LRP1-deficient mice (macLRP1−/−) generated on a low-density lipoprotein receptor knockout (LDLR−/−) background and fed a Western diet. LDLR−/−; macLRP1−/− mice gained less body weight and had improved glucose tolerance compared to LDLR−/− mice. Livers from LDLR−/−; macLRP1−/− mice displayed lower levels of gene expression for several inflammatory cytokines, including Ccl3, Ccl4, Ccl8, Ccr1, Ccr2, Cxcl9, and Tnf, and reduced phosphorylation of GSK3α and p38 MAPK proteins. Furthermore, LRP1-deficient peritoneal macrophages displayed altered cholesterol metabolism. Finally, circulating levels of sFRP-5, a potent anti-inflammatory adipokine that functions as a decoy receptor for Wnt5a, were elevated in LDLR−/−; macLRP1−/− mice. Surface plasmon resonance experiments revealed that sFRP-5 is a novel high affinity ligand for LRP1, revealing that LRP1 regulates levels of this inhibitor of Wnt5a-mediated signaling. Collectively, our results suggest that LRP1 expression in macrophages promotes hepatic inflammation and the development of glucose intolerance and insulin resistance by modulating Wnt signaling.

Effect of taurine on cholesterol metabolism in hamsters: Up-regulation of low density lipoprotein (LDL) receptor by taurine

Life Sciences ◽  
2002 ◽  
Vol 70 (20) ◽  
pp. 2355-2366 ◽  
Author(s):  
Shigeru Murakami ◽  
Yukiko Kondo ◽  
Yoshihisa Toda ◽  
Hideaki Kitajima ◽  
Kazuya Kameo ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Low Density
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