losartan-potassium and Fatty-Liver

Erythropoietin (EPO), known primarily for its role in erythropoiesis, was recently reported to play a beneficial role in regulating lipid metabolism; however, the underlying mechanism through which EPO decreases hepatic lipid accumulation requires further investigation. Endoplasmic reticulum (ER) stress may contribute to the progression of hepatic steatosis. The present study investigated the effects of EPO on regulating ER stress in fatty liver. It was demonstrated that EPO inhibited hepatic ER stress and steatosis in vivo and in vitro. Interestingly, these beneficial effects were abrogated in liver‑specific sirtuin 1 (SIRT1)‑knockout mice compared with wild‑type littermates. In addition, in palmitate‑treated hepatocytes, small interfering RNA‑mediated SIRT1 silencing suppressed the effects of EPO on lipid‑induced ER stress. Additionally, EPO stimulated hepatic fibroblast growth factor 21 (FGF21) expression and secretion in a SIRT1‑dependent manner in mice. Furthermore, the sensitivity of hepatocytes from obese mice to FGF21 was restored following treatment with EPO. Collectively, the results of the present study revealed a new mechanism underlying the regulation of hepatic ER stress and FGF21 expression induced by EPO; thus, EPO may be considered as a potential therapeutic agent for the treatment of fatty liver and obesity.

Topics: Animals; Cells, Cultured; Endoplasmic Reticulum Stress; Erythropoietin; Fatty Liver; Fibroblast Growth Factors; Male; Mice, Inbred C57BL; Obesity; Up-Regulation

Erythropoietin (EPO), besides its stimulatory effect on erythropoiesis, is beneficial to insulin resistance and obesity. However, its role in hepatic steatosis remains unexplored. Activating autophagy seems a promising mechanism for improving fatty liver disease. The present study investigated the role of EPO in alleviating hepatic steatosis and sought to determine whether its function is mediated by the activation of autophagy. Here, we show that EPO decreased hepatic lipid content significantly in vivo and in vitro. Furthermore, EPO/EPO receptor (EPOR) signalling induced autophagy activation in hepatocytes as indicated by western blot assay, transmission electron microscopy, and confocal microscopy. In addition, EPO increased the co-localization of autophagosomes and cellular lipids as shown by double labelling of the autophagy marker light chain microtubule-associated protein 3 (LC3) and lipids. Importantly, suppression of autophagy by an inhibitor or small interfering RNA (siRNA) abolished the EPO-mediated alleviation hepatic steatosis in vitro. Furthermore, EPO up-regulated sirtuin 1 (SIRT1) expression, and siRNA-mediated SIRT1 silencing abrogated the EPO-induced increases in LC3 protein and deacetylation levels, thereby preventing the alleviation of hepatic steatosis. Taken together, this study revealed a new mechanism wherein EPO alleviates hepatic steatosis by activating autophagy via SIRT1-dependent deacetylation of LC3. This finding might have therapeutic value in the treatment of hepatic steatosis.

Topics: Acetylation; Animals; Autophagy; Erythropoietin; Fatty Liver; Mice; Mice, Obese; Microtubule-Associated Proteins; Sirtuin 1

Erythropoietin (Epo) is produced in the kidney and liver in a hypoxia-inducible manner via the activation of hypoxia-inducible transcription factors (HIFs) to maintain oxygen homeostasis. Accelerating Epo production in hepatocytes is one plausible therapeutic strategy for treating anemia caused by kidney diseases. To elucidate the regulatory mechanisms of hepatic Epo production, we analyzed mouse lines harboring liver-specific deletions of genes encoding HIF-prolyl-hydroxylase isoforms (PHD1, PHD2, and PHD3) that mediate the inactivation of HIF1α and HIF2α under normal oxygen conditions. The loss of all PHD isoforms results in both polycythemia, which is caused by Epo overproduction, and fatty livers. We found that deleting any combination of two PHD isoforms induces polycythemia without steatosis complications, whereas the deletion of a single isoform induces no apparent phenotype. Polycythemia is prevented by the loss of either HIF2α or the hepatocyte-specific Epo gene enhancer (EpoHE). Chromatin analyses show that the histones around EpoHE dissociate from the nucleosome structure after HIF2α activation. HIF2α also induces the expression of HIF3α, which is involved in the attenuation of Epo production. These results demonstrate that the total amount of PHD activity is more important than the specific function of each isoform for hepatic Epo expression regulated by a PHD-HIF2α-EpoHE cascade in vivo.

Topics: Anemia; Animals; Apoptosis Regulatory Proteins; Basic Helix-Loop-Helix Transcription Factors; Cell Hypoxia; Cell Line, Tumor; Enzyme Activation; Erythropoietin; Fatty Liver; Hepatocytes; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia-Inducible Factor-Proline Dioxygenases; Liver; Mice; Mice, Knockout; Polycythemia; Procollagen-Proline Dioxygenase; Repressor Proteins; Signal Transduction; Transcription Factors; Transcription, Genetic

Ischemia reperfusion injury (IRI) is a primary concern in liver transplantation, especially when steatosis is present. Acetazolamide (AZ), a specific carbonic anhydrase (CA) inhibitor, has been suggested to protect against hypoxia. Here, we hypothesized that AZ administration could be efficient to protect fatty livers against cold IRI. Obese Zucker rat livers were preserved in Institut Georges Lopez-1 storage solution for 24 hours at 4°C and ex vivo perfused for 2 hours at 37°C. Alternatively, rats were also treated with intravenous injection of AZ (30 mg/kg) before liver recovery. Liver injury, hepatic function, and vascular resistance were determined. CA II protein levels and CA hydratase activity were assessed as well as other parameters involved in IRI (endothelial nitric oxide synthase, mitogen activated protein kinase family, hypoxic inducible factor 1 alpha, and erythropoietin). We demonstrated that AZ administration efficiently protects the steatotic liver against cold IRI. AZ protection was associated with better function, decreased vascular resistance, and activation of endothelial nitric oxide synthase. This was consistent with an effective mitogen activated protein kinase inactivation. Finally, no effect on the hypoxic inductible factor 1 alpha/erythropoietin pathway was observed. The present study demonstrated that AZ administration is a suitable pharmacological strategy for preserving fatty liver grafts against cold IRI.

Topics: Acetazolamide; Animals; Carbonic Anhydrase II; Carbonic Anhydrase Inhibitors; Cold Temperature; Enzyme Activation; Erythropoietin; Extracellular Signal-Regulated MAP Kinases; Fatty Liver; Hypoxia-Inducible Factor 1, alpha Subunit; JNK Mitogen-Activated Protein Kinases; Liver; Liver Transplantation; Male; Nitric Oxide Synthase Type III; Organ Preservation; Phosphorylation; Rats, Zucker; Reperfusion Injury; Vascular Resistance

The haematopoietic activity of erythropoietin (EPO) is mediated by the classic EPO receptor (EpoR) homodimer, whereas tissue-protective effects are mediated by a heterocomplex between EpoR and the β-common receptor (βcR). Here, we investigated the effects of a novel, selective ligand of this heterocomplex - pyroglutamate helix B surface peptide (pHBSP) - in mice fed a diet enriched in sugars and saturated fats.. Male C57BL/6J mice were fed a high-fat high-sucrose diet (HFHS) for 22 weeks. pHBSP (30 μg·kg(-1) s.c.) was administered for the last 11 weeks. Biochemical assays, histopathological and immunohistochemical examinations and Western blotting were performed on serum and target organs (liver, kidney and skeletal muscle).. Mice fed with HFHS diet exhibited insulin resistance, hyperlipidaemia, hepatic lipid accumulation and kidney dysfunction. In gastrocnemius muscle, HFHS impaired the insulin signalling pathway and reduced membrane translocation of glucose transporter type 4 and glycogen content. Treatment with pHBSP ameliorated renal function, reduced hepatic lipid deposition, and normalized serum glucose and lipid profiles. These effects were associated with an improvement in insulin sensitivity and glucose uptake in skeletal muscle. Diet-induced overproduction of the myokines IL-6 and fibroblast growth factor-21 were attenuated by pHBSP and, most importantly, pHBSP markedly enhanced mitochondrial biogenesis in skeletal muscle.. Chronic treatment of mice with an EPO derivative, devoid of haematopoietic effects, improved metabolic abnormalities induced by a high-fat high-sucrose diet, by affecting several levels of the insulin signalling and inflammatory cascades within skeletal muscle, while enhancing mitochondrial biogenesis.

Topics: Animals; Blood Glucose; Dietary Fats; Dietary Sucrose; Erythropoietin; Fatty Liver; Hyperlipidemias; Insulin Resistance; Kidney; Liver; Male; Mice; Mice, Inbred C57BL; Muscle, Skeletal; Oligopeptides; Renal Insufficiency

Fatty liver disease increases the risk in major liver resection for patients. As previous studies suggested that vascular endothelial growth factor (VEGF) and erythropoietin (EPO) might improve liver regeneration in nonobese animals, we investigated their effect after subtotal hepatectomy (SH) in rats with diet-induced steatosis.. Male Wistar rats were fed with fatty liver-inducing diet (FLD) or normal diet (control) for 11-12 weeks followed by 90% SH. Animals were treated either with EPO, VEGF or NaCl on postoperative days 0, 1 and 3 and sacrificed 24 h or 7 days after SH. Survival rate, liver regeneration and biochemical markers were assessed. Expression of inflammatory cytokines (TNF-α, IL-6) and apoptosis-related genes (PUMA, Bcl-2) was measured by qRT-PCR.. Seven-day survival after SH was significantly decreased in the FLD group compared to controls (50 vs. 100%, p < 0.05). In FLD animals, treatment with VEGF increased 7-day survival to 90% compared to only 40% in the EPO group. After surgery, blood glucose levels of VEGF but not EPO- or NaCl-treated animals remained normal. Inflammatory genes were markedly upregulated in the EPO group 24 h after SH.. Steatosis severely impairs survival and regeneration after extensive liver resection, which can be counteracted at least in part by perioperative treatment with VEGF.

Topics: Animals; Apoptosis Regulatory Proteins; Blood Glucose; Diet; Disease Models, Animal; Erythropoietin; Fatty Liver; Gene Expression; Genes, bcl-2; Gluconeogenesis; Hepatectomy; Interleukin-6; Liver Regeneration; Male; Rats; Rats, Wistar; Survival Rate; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A

Organ shortage in liver transplantation has justified usage of marginal donor livers to expand the donor organ pool. The particular susceptibility of steatotic livers to I/R injury necessitates optimal preservation conditions in order to minimize preservation-reperfusion injury for successful transplantation.. The effect of erythropoietin (EPO) as additive to HTK preservation solution was studied in a mouse model. Lean and steatotic livers were harvested, stored for 24 h in 4°C HTK solution containing either EPO or saline and reperfused for 2 h with 37°C Krebs-Henseleit buffer. Livers without cold storage served as sham controls.. Flushing of livers upon cold storage revealed a transaminase release, which was 2- to 10-fold higher in steatotic versus lean livers. EPO was effective in reducing the enzyme release to 50% in steatotic but not in lean livers. EPO prevented cold storage-induced denudation of the endothelial lining in steatotic livers, but aggravated it in lean livers. During reperfusion, steatotic livers presented with lower oxygen consumption and higher enzyme release than lean livers. In all livers, parameters of reperfusion injury remained unaffected by EPO. Expression of UCP2 was found markedly higher in steatotic livers. After I/R, steatotic livers revealed a significant drop of UCP2, whereas expression in lean livers was only slightly affected. EPO diminished Erk phosphorylation to almost the same extent in both mouse strains.. Fortification of the preservation solution by EPO ameliorates cold ischemic injury of steatotic livers and may thus be considered for use as an adjunctive agent to increase the success of transplanting steatotic livers.

Topics: Animals; Cold Temperature; Disease Models, Animal; Erythropoietin; Fatty Liver; Female; Glucose; Ion Channels; Liver; Liver Transplantation; Male; Mannitol; Mice; Mice, Inbred Strains; Mice, Obese; Mitochondrial Proteins; Mitogen-Activated Protein Kinase Kinases; Obesity; Organ Preservation Solutions; Potassium Chloride; Procaine; Receptors, Erythropoietin; Reperfusion Injury; Signal Transduction; Thinness; Uncoupling Protein 2

Graft dysfunction of steatotic livers (SL) still remains a major challenge in liver transplantation. Different mechanisms are thought to be involved in the impaired tolerance of SL to ischemia-reperfusion injury. Thus, different pharmacologic strategies may need to be combined to effectively protect SL and to reduce graft dysfunction after transplantation. Therefore, we analyzed the effectiveness of a multidrug donor preconditioning (MDDP) procedure to protect SL from cold ischemia-reperfusion injury.. Liver steatosis was induced by a high-carbohydrate, fat-free diet. A total of 24 Sprague-Dawley rats were divided into 3 groups (n = 8 each), including a control group with nonsteatotic livers (Con), a vehicle-treated SL group (SL-Con), and a SL group undergoing MDDP (SL-MDDP), including pentoxyphylline, glycine, deferoxamine, N-acetylcysteine, erythropoietin, melatonin, and simvastatin. MDDP was applied before liver perfusion with 4°C histidine-tryptophan-ketoglutarate (HTK) solution and organ harvest. After 24 hours of cold storage in HTK, postischemic reperfusion was performed in an isolated liver reperfusion model using 37°C Krebs-Henseleit bicarbonate buffer.. After 60 minutes of reperfusion, SL showed a significant reduction of bile flow as well as a marked increase of liver enzyme levels and apoptotic cell death compared with Con. This was associated with an increased malondialdehyde formation, interleukin-1 production, and leukocytic tissue infiltration. MDDP completely abolished the inflammatory response and was capable of significantly reducing parenchymal dysfunction and injury.. MDDP decreases SL injury after cold storage and reperfusion. The concept of MDDP as a simple and safe preoperative regime, thus may be of interest in clinical use, expanding the donor pool from marginal donors.

Topics: Animals; Antioxidants; Cold Ischemia; Disease Models, Animal; Drug Therapy, Combination; Erythropoietin; Fatty Liver; Female; Glycine Agents; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Ischemic Preconditioning; Liver; Liver Transplantation; Male; Primary Graft Dysfunction; Rats; Rats, Sprague-Dawley; Siderophores; Tissue Donors

The scarcity of appropriate donor organs remains to be a major problem in transplantation surgery today. This has led to increased acceptance of so-called marginal grafts, incorporating the increased risk of poor posttransplant function. Erythropoietin has been shown to reduce ischemia-reperfusion injury in transplanted rat livers. We investigated whether these capacities may contribute to improve marginal organ function.. One hundred and forty Lewis rats were used. Fatty liver (>or=50% steatosis) was induced by a special diet in 70 donor animals. Seventy recipients received liver transplantation after donor organ treatment with 1000 IU rhuEpo or saline injection (controls) into portal veins (cold ischemia 6 hr, University of Wisconsin solution). Recipients were allocated to two groups which received 1000 IU rHuEpo at reperfusion or an equal amount of saline (control). Analysis of liver enzymes, histology (hematoxylin-eosin and periodic acid Schiff stain), immunostaining (terminal deoxynucleotide transferase- mediated dUTP nick-end labeling, hypoxyprobe, and tumor necrosis factor-alpha), and reverse transcriptase-polymerase chain reaction of cytokine messenger RNA (interleukin-1, interleukin-6, hypoxia induced factor-1 alpha, vascular endothelial growth factor, and hepatocyte growth factor) were performed at defined time points (2, 4.5, 24, 48 hr, and 7 days postoperatively).. Alanine aminotransferase values were significantly reduced for epo-treated rats 48 hr after reperfusion; however, at all other time points enzyme levels were without significant differences. Terminal deoxynucleotide transferase-mediated dUTP nick-end labeling and hypoxyprobe analysis and necrotic index evaluation displayed significant reduction of apoptosis and hypoxic cells in rHuEpo-treated graft livers. Overall survival was significantly improved among epo-treated rats.. Erythropoietin improves marginal graft function and recipient survival after transplantation of fatty livers in rats.

Topics: Animals; Erythropoietin; Fatty Liver; Graft Rejection; Graft Survival; Hepatocyte Growth Factor; Humans; Interleukin-1beta; Interleukin-6; Liver Transplantation; Male; Rats; Rats, Inbred Lew; Recombinant Proteins; RNA, Messenger; Survival Rate; Survivors; Transplantation, Homologous; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A