scholarly journals FXR activation by obeticholic acid or nonsteroidal agonists induces a human-like lipoprotein cholesterol change in mice with humanized chimeric liver

2018 ◽  
Vol 59 (6) ◽  
pp. 982-993 ◽  
Author(s):  
Romeo Papazyan ◽  
Xueqing Liu ◽  
Jingwen Liu ◽  
Bin Dong ◽  
Emily M. Plummer ◽  
...  
Keyword(s):  
Target Gene ◽  
Ldl Cholesterol ◽  
Ldl Receptor ◽  
Hdl Cholesterol ◽  
Farnesoid X Receptor ◽  
Receptor Protein ◽  
Chimeric Mice ◽  
Obeticholic Acid ◽  
Protein Levels ◽  
Mechanistic Basis

Obeticholic acid (OCA) is a selective farnesoid X receptor (FXR) agonist that regulates bile acid and lipid metabolism. FXR activation induces distinct changes in circulating cholesterol among animal models and humans. The mechanistic basis of these effects has been elusive because of difficulties in studying lipoprotein homeostasis in mice, which predominantly package circulating cholesterol in HDLs. Here, we tested the effects of OCA in chimeric mice whose livers are mostly composed (≥80%) of human hepatocytes. Chimeric mice exhibited a human-like ratio of serum LDL cholesterol (LDL-C) to HDL cholesterol (HDL-C) at baseline. OCA treatment in chimeric mice increased circulating LDL-C and decreased circulating HDL-C levels, demonstrating that these mice closely model the cholesterol effects of FXR activation in humans. Mechanistically, OCA treatment increased hepatic cholesterol in chimeric mice but not in control mice. This increase correlated with decreased SREBP-2 activity and target gene expression, including a significant reduction in LDL receptor protein. Cotreatment with atorvastatin reduced total cholesterol, rescued LDL receptor protein levels, and normalized serum LDL-C. Treatment with two clinically relevant nonsteroidal FXR agonists elicited similar lipoprotein and hepatic changes in chimeric mice, suggesting that the increase in circulating LDL-C is a class effect of FXR activation.

Abstract 203: Role of Glucagon Receptor Signalling in PCSK9 Regulation

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Stefano Spolitu ◽  
Lale Ozcan
Keyword(s):  
Lipid Metabolism ◽  
Blood Glucose ◽  
Ldl Cholesterol ◽  
Cholesterol Metabolism ◽  
Ldl Receptor ◽  
Receptor Protein ◽  
Obese Mice ◽  
Glucagon Receptor ◽  
Protein Levels ◽  
New Findings

Excessive glucagon receptor action in hepatocytes is a major contributing factor to type 2 diabetes (T2D). Accordingly, there has been great interest in developing glucagon receptor antagonists (GRAs) as a treatment for T2D. Although phase 2 clinical trials have shown that GRAs effectively lower blood glucose in T2D subjects, they increase plasma low density lipoprotein (LDL) cholesterol levels, which has presented a significant block to their development. In this context, recent studies have suggested that cholesterol and proprotein convertase subtilisin/kexin type 9 (PCSK9) levels can be regulated by fasting and perhaps glucagon, but in-depth mechanistic insight is lacking. In order to test the functional importance of hepatic glucagon action on lipid metabolism, we silenced glucagon receptor (GcgR) in obese mice using AAV8-H1-shGcgr to silence the receptor in hepatocytes. Consistent with previous reports, this treatment effectively lowered blood glucose in obese mice without a change in body weight. Moreover, GcgR silencing, like GRAs in humans, significantly increased plasma LDL cholesterol. In search for the mechanism, we found that inhibition of GcgR significantly lowered hepatic LDL-receptor protein levels and increased both hepatic PCSK9 and circulating PCSK9. To determine causation, we treated GcgR-silenced mice with a neutralizing monoclonal antibody against PCSK9 and found that this intervention restored hepatic LDL-receptor protein levels and prevented the increase in LDL cholesterol. Further mechanistic work revealed that GcgR silencing in hepatocytes did not increase Pcsk9 mRNA. Rather, blocking GcgR increased the half-life of PCSK9 protein by suppressing signalling through exchange protein activated by cAMP 1 (Epac1). In particular, the ability of GcgR silencing to increase PCSK9 and suppress LDL receptor protein levels was mimicked by hepatocytes lacking Epac1. Thus, GcgR signalling through Epac1 appears to have critical effects on processes that regulate cholesterol metabolism through PCSK9. These new findings have important implications for the lipid metabolism effects of hepatic glucagon signalling in both normal physiology and metabolic disease, and for the development of safer GRA-like drugs to treat T2D.

scholarly journals Potential of therapeutic bile acids in the treatment of neonatal Hyperbilirubinemia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lori W. E. van der Schoor ◽  
Henkjan J. Verkade ◽  
Anna Bertolini ◽  
Sanne de Wit ◽  
Elvira Mennillo ◽  
...  
Keyword(s):  
Bile Acids ◽  
Treatment Options ◽  
Preventive Treatment ◽  
Neonatal Hyperbilirubinemia ◽  
Farnesoid X Receptor ◽  
Neurological Damage ◽  
Obeticholic Acid ◽  
Protein Levels ◽  
Gunn Rats ◽  
Plasma Bilirubin

AbstractNeonatal hyperbilirubinemia or jaundice is associated with kernicterus, resulting in permanent neurological damage or even death. Conventional phototherapy does not prevent hyperbilirubinemia or eliminate the need for exchange transfusion. Here we investigated the potential of therapeutic bile acids ursodeoxycholic acid (UDCA) and obeticholic acid (OCA, 6-α-ethyl-CDCA), a farnesoid-X-receptor (FXR) agonist, as preventive treatment options for neonatal hyperbilirubinemia using the hUGT1*1 humanized mice and Ugt1a-deficient Gunn rats. Treatment of hUGT1*1 mice with UDCA or OCA at postnatal days 10–14 effectively decreased bilirubin in plasma (by 82% and 62%) and brain (by 72% and 69%), respectively. Mechanistically, our findings indicate that these effects are mediated through induction of protein levels of hUGT1A1 in the intestine, but not in liver. We further demonstrate that in Ugt1a-deficient Gunn rats, UDCA but not OCA significantly decreases plasma bilirubin, indicating that at least some of the hypobilirubinemic effects of UDCA are independent of UGT1A1. Finally, using the synthetic, non-bile acid, FXR-agonist GW4064, we show that some of these effects are mediated through direct or indirect activation of FXR. Together, our study shows that therapeutic bile acids UDCA and OCA effectively reduce both plasma and brain bilirubin, highlighting their potential in the treatment of neonatal hyperbilirubinemia.

scholarly journals Plasma PCSK9 Concentrations Correlate with LDL and Total Cholesterol in Diabetic Patients and Are Decreased by Fenofibrate Treatment

2008 ◽  
Vol 54 (6) ◽  
pp. 1038-1045 ◽  
Author(s):  
Gilles Lambert ◽  
Nicolas Ancellin ◽  
Francesca Charlton ◽  
Daniel Comas ◽  
Julia Pilot ◽  
...  
Keyword(s):  
Ldl Cholesterol ◽  
Polyclonal Antibodies ◽  
Sandwich Elisa ◽  
Ldl Receptor ◽  
Hdl Cholesterol ◽  
Diabetic Patients ◽  
Plasma Triglycerides ◽  
Fenofibrate Treatment ◽  
Before And After ◽  
Fenofibrate Intervention

Abstract Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the LDL receptor (LDLr) in hepatocytes, and its expression in mouse liver has been shown to decrease with fenofibrate treatment. Methods: We developed a sandwich ELISA using recombinant human PCSK9 protein and 2 affinity-purified polyclonal antibodies directed against human PCSK9. We measured circulating PCSK9 concentrations in 115 diabetic patients from the FIELD (Fenofibrate Intervention and Event Lowering in Diabetes) study before and after fenofibrate treatment. Results: We found that plasma PCSK9 concentrations correlate with total (r = 0.45, P = 0.006) and LDL (r = 0.54, P = 0.001) cholesterol but not with triglycerides or HDL cholesterol concentrations in that cohort. After 6 weeks of treatment with comicronized fenofibrate (200 mg/day), plasma PCSK9 concentrations decreased by 8.5% (P = 0.041 vs pretreatment). This decrease correlated with the efficacy of fenofibrate, as judged by a parallel reduction in plasma triglycerides (r = 0.31, P = 0.015) and LDL cholesterol concentrations (r = 0.27, P = 0.048). Conclusions: We conclude that this decrease in PCSK9 explains at least in part the LDL cholesterol–lowering effects of fenofibrate. Fenofibrate might be of interest to further reduce cardiovascular risk in patients already treated with a statin.

scholarly journals Familial Hypercholesterolemia: Three “under” (Understood, Underdiagnosed, and Undertreated) Disease

2021 ◽  
Author(s):  
Vladimir O. Konstantinov
Keyword(s):  
Familial Hypercholesterolemia ◽  
Time Course ◽  
Ldl Cholesterol ◽  
Genetic Disorders ◽  
Receptor Gene ◽  
Ldl Receptor ◽  
Hdl Cholesterol ◽  
Blood Cholesterol ◽  
Healthy Population ◽  
Loss Of Function

Familial hypercholesterolemia (FH) is one of the most prevalent genetic disorders leading to premature atherosclerosis and coronary heart disease. The main cause of FH is a mutation in the LDL-receptor gene that leads to loss of function of these receptors causing high levels of blood cholesterol. The diagnosis of FH is not very easy. Wide screenings are needed to reveal high levels of LDL cholesterol among “healthy” population. If the patient has MI or stroke at an early age, high levels of LDL cholesterol, and tendon xanthomas, the diagnosis of FH becomes much more clear. Genetic testing is a gold standard in the diagnosis of FH. There are several factors, influencing the time course of FH. Smoking males with low levels of HDL cholesterol have an extremely higher risk of death than nonsmoking females with high HDL cholesterol. Management of FH includes low cholesterol diet, statin and ezetimibe treatment, PCSK inhibitors, and LDL aphaeresis. Early and effective treatment influences much the prognosis in FH patients.

Obeticholic acid raises LDL-cholesterol and reduces HDL-cholesterol in the Diet-Induced NASH (DIN) hamster model

2018 ◽  
Vol 818 ◽  
pp. 449-456 ◽  
Author(s):  
François Briand ◽  
Emmanuel Brousseau ◽  
Marjolaine Quinsat ◽  
Rémy Burcelin ◽  
Thierry Sulpice
Keyword(s):  
Ldl Cholesterol ◽  
Hdl Cholesterol ◽  
Obeticholic Acid ◽  
Hamster Model

scholarly journals Proprotein convertase subtilisin/kexin type 9 (PCSK9) levels are not associated with severity of liver disease and are inversely related to cholesterol in a cohort of thirty eight patients with liver cirrhosis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Susanne Feder ◽  
Reiner Wiest ◽  
Thomas S. Weiss ◽  
Charalampos Aslanidis ◽  
Doris Schacherer ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Liver Disease ◽  
Cholesteryl Ester ◽  
Hepatic Vein ◽  
Cholesterol Metabolism ◽  
Ldl Receptor ◽  
Receptor Protein ◽  
Proprotein Convertase ◽  
Protein Levels ◽  
Systemic Vein

Abstract Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) is of particular importance in cholesterol metabolism with high levels contributing to hypercholesterolemia. Cholesterol and sphingolipids are low in patients with liver cirrhosis. Purpose of this study was to find associations of plasma PCSK9 with circulating cholesterol and sphingolipid species and measures of liver disease severity in patients with liver cirrhosis. Methods PCSK9 protein levels were determined by ELISA in systemic vein (SVP), hepatic vein (HVP) and portal vein plasma of patients with mostly alcoholic liver cirrhosis. PCSK9 and LDL-receptor protein expression were analysed in cirrhotic and non-cirrhotic liver tissues. Results Serum PCSK9 was reduced in patients with liver cirrhosis in comparison to non-cirrhotic patients. In liver cirrhosis, plasma PCSK9 was not correlated with Child-Pugh score, Model for End-Stage Liver Disease score, bilirubin or aminotransferases. A negative association of SVP PCSK9 with albumin existed. PCSK9 protein in the liver did not change with fibrosis stage and was even positively correlated with LDL-receptor protein levels. Ascites volume and variceal size were not related to PCSK9 levels. Along the same line, transjugular intrahepatic shunt to lower portal pressure did not affect PCSK9 concentrations in the three blood compartments. Serum cholesterol, sphingomyelin and ceramide levels did not correlate with PCSK9. Stratifying patients by high versus low PCSK9 levels using the median as cut-off, several cholesteryl ester species were even low in the subgroup with high PCSK9 levels. A few sphingomyelin species were also reduced in the patients with PCSK9 levels above the median. PCSK9 is highly expressed in the liver but systemic, portal and hepatic vein levels were similar. PCSK9 was not correlated with the inflammatory proteins C-reactive protein, IL-6, galectin-3, resistin or pentraxin 3. Of note, HVP PCSK9 was positively associated with HVP chemerin and negatively with HVP adiponectin levels. Conclusions In the cohort of patients with liver cirrhosis mostly secondary to alcohol consumption high PCSK9 was associated with low levels of certain cholesteryl ester and sphingomyelin species. Positive correlations of PCSK9 and LDL-receptor protein in the liver of patients with chronic liver injury are consistent with these findings.

Abstract 20310: Cardiovascular Risk Markers in a Large Cohort of Children With Genetically Verified FH Show No Inheritance-Related but LDL Receptor Mutation-Type and Family History of CVD-related Variance

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ingunn Narverud ◽  
Jeaninen R van Lennep ◽  
Jacob J Christensen ◽  
Jorie Versmissen ◽  
Jon M Gran ◽  
...  
Keyword(s):  
Family History ◽  
Mixed Model ◽  
Ldl Cholesterol ◽  
Plasma Lipids ◽  
Receptor Gene ◽  
Ldl Receptor ◽  
Hdl Cholesterol ◽  
Premature Cardiovascular Disease ◽  
History Of ◽  
The Impact

Introduction: Familial hypercholesterolemia (FH) is an autosomal dominant disease caused primarily by mutations in the low density lipoprotein (LDL) receptor gene. FH patients have increased total- and LDL cholesterol leading to accelerated atherosclerosis and premature cardiovascular disease (CVD). In an FH pregnancy the absolute rise in lipid levels are often much higher than in healthy pregnancies, and this maternal hypercholesterolemia may thus contribute to an unfavorable in utero environment potentially increasing susceptibility of adult CVD. Few studies have investigated whether maternal FH is associated with an unfavorable phenotype in offspring compared with paternal FH inheritance. Hypothesis: The aim of the present study was to investigate the impact of maternal vs. paternal FH on pre-treated plasma lipids. In addition, the effect of LDL receptor mutation types and Family history of early CVD in FH children was evaluated Methods: We included 1063 children with FH (0-19 years) in the study. Five-hundred had inherited FH maternally and 563 paternally. Furthermore, 624 children with FH had an LDL receptor negative mutation and 332 of the FH children had an FH grandparent suffering from early CVD whereas the remaining children had an FH grandparent with late or no CVD. Differences were tested for using a random intercept mixed model taking account for between-family variation. Results: Children with maternal FH did not have different levels of total-, LDL- or HDL-cholesterol, triglycerides, apoA1, apoB, lipoprotein (a) compared with children With paternal FH. Moreover, children with LDL receptor negative mutations had higher levels of total- and LDL cholesterol in addition to apoB, and concomitantly lower levels of HDL-cholesterol and apoA-1 than children with other LDL receptor mutations. Finally, children with an FH grandparent with early CVD had significant higher LDL-cholesterol levels than children without. Conclusions: Maternal FH does not lead to a more unfavorable phenotype in untreated FH children. However, both FH children with LDL receptor negative mutation and FH children with early CVD in family had a more unfavorably phenotype. Hence statin treatment should potentially be initialized earlier in this group.

scholarly journals Diminished Vitamin D Receptor Protein Levels in Crohn’s Disease Fibroblasts: Effects of Vitamin D

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 973
Author(s):  
Laura Gisbert-Ferrándiz ◽  
Jesús Cosín-Roger ◽  
Carlos Hernández ◽  
Dulce C. Macias-Ceja ◽  
Dolores Ortiz-Masiá ◽  
...  
Keyword(s):  
Vitamin D ◽  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Epithelial Cells ◽  
Vitamin D Receptor ◽  
Receptor Protein ◽  
Intestinal Fibrosis ◽  
Protein Levels ◽  
Therapeutic Value ◽  
Mechanistic Basis

Vitamin D (VD) deficiency has been associated to Crohn’s disease (CD) pathogenesis, and the exogenous administration of VD improves the course of the disease, but the mechanistic basis of these observations remains unknown. Vitamin D receptor (VDR) mediates most of the biological functions of this hormone, and we aim to analyze here the expression of VDR in intestinal tissue, epithelial cells, and fibroblasts from CD patients. The effects of VD on a fibroblast wound healing assay and murine intestinal fibrosis are also analyzed. Our data show diminished VDR protein levels in surgical resections and epithelial cells from CD patients. In intestinal fibroblasts isolated from damaged tissue of CD patients, we detected enhanced migration and decreased VDR expression compared with both fibroblasts from non-damaged tissue of the same CD patient or control fibroblasts. Treatment with VD increased VDR protein levels, avoided the accelerated migration in CD fibroblasts, and prevented murine intestinal fibrosis induced by the heterotopic transplant model. In conclusion, our study demonstrates diminished VDR protein levels associated with enhanced migration in intestinal fibroblasts from damaged tissue of CD patients. In these cells, VD accumulates VDR and normalizes migration, which supports that CD patients would benefit from the VD anti-fibrotic therapeutic value that we demonstrate in a murine experimental model.

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