scholarly journals Fatty acid-induced lipotoxicity inhibits choline metabolism independent of ER stress in mouse primary hepatocytes

2019 ◽  
Author(s):  
Conor O’Dwyer ◽  
Rebecca Yaworski ◽  
Nicholas D. LeBlond ◽  
Peyman Ghorbani ◽  
Julia R.C. Nunes ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Er Stress ◽  
Fatty Liver Disease ◽  
Choline Uptake ◽  
Primary Hepatocytes ◽  
Compensatory Mechanisms ◽  
Choline Transport ◽  
Alcoholic Fatty Liver ◽  
Choline Metabolism

ABSTRACTCholine is an essential nutrient that is critical component of the membrane phospholipid phosphatidylcholine (PC), the neurotransmitter acetylcholine and the methylation pathway. In the liver specifically, PC is the major membrane constituent and can be synthesized by the CDP-choline or the phosphatidylethanolamine (PE) N-methyltransferase (PEMT) pathway. With the continuing global rise in the rates of obesity and non-alcoholic fatty liver disease, we sought to explore how excess fatty acids (FA), typical of an obesity and hepatic steatosis, affect choline uptake and metabolism in primary hepatocytes. Our results demonstrate that hepatocytes chronically treated with palmitate, but not oleate or a mixture, had decreased choline uptake, which was associated with lower choline incorporation into PC and lower expression of choline transport proteins. Interestingly, a reduction in the rate of degradation spared PC levels in response to palmitate when compared to control. PE synthesis was slightly diminished; however, no compensatory changes in the PEMT pathway were observed. We next hypothesized that ER stress may be a potential mechanism by which palmitate treatment diminished choline. However, when we exposed primary hepatocytes to the common ER stress inducing compound tunicamycin, choline uptake, contrary to our expectation was augmented, concomitant with the transcript expression of choline transporters. Moreover, tunicamycin-induced ER stress divorced the observed increase in choline uptake from CDP-choline pathway flux since ER stress significantly diminished the incorporation and total PC content, similar to PE. Conclusion: Therefore, our results suggest that the altered FA milieu seen in obesity and fatty liver disease progression may adversely affect choline metabolism, but that compensatory mechanisms work to maintain phospholipid homeostasis.Abstract Figure

GCSF deficiency attenuates non-alcoholic fatty liver disease through regulating GCSFR-SOCS3-JAK-STAT3 pathway and immune cells infiltration

2021 ◽  
Author(s):  
Yuwei Zhang ◽  
Xuefeng Zhou ◽  
Peihao Liu ◽  
Xueyang Chen ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Immune Cells ◽  
Fatty Liver Disease ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Primary Hepatocytes ◽  
Alcoholic Fatty Liver ◽  
Stimulating Factor ◽  
Alcoholic Fatty Liver Disease

Granulocyte colony stimulating factor (GCSF) is a cytokine with immunomodulation effects. However, little is known about its role in metabolic diseases. In the current study we aimed to explore the role of GCSF in non-alcoholic fatty liver disease (NAFLD). GCSF-/- mice were used to investigate the function of GCSF in vivo after high fat diet (HFD). Primary hepatocytes were used for evaluating the function of GCSF in vitro. Liver immune cells were isolated and analyzed by flow cytometry. Our results showed that GCSF administration significantly increased serum triglyceride (TG) levels in patients. Circulating GCSF was markedly elevated in HFD-fed mice. GCSF-/- mice exhibited alleviated HFD-induced obesity, insulin resistance and hepatic steatosis. Extra administration of GCSF significantly aggravated palmitic acid (PA)-induced lipid accumulation in primary hepatocytes. Mechanically, GCSF could bind to granulocyte colony stimulating factor receptor (GCSFR) and regulate suppressors of cytokine signaling 3, Janus kinase, signal transducer and activator of transcription 3 (SOCS3-JAK-STAT3) pathway. GCSF also enhanced hepatic neutrophils and macrophages infiltration, thereby modulating NAFLD. These findings suggest that GCSF plays an important regulatory role in NAFLD and may be a potential therapeutic target for NAFLD.

scholarly journals Melatonin Effects on Non-Alcoholic Fatty Liver Disease Are Related to MicroRNA-34a-5p/Sirt1 Axis and Autophagy

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1053 ◽  
Author(s):  
Alessandra Stacchiotti ◽  
Ilaria Grossi ◽  
Raquel García-Gómez ◽  
Gaurangkumar Patel ◽  
Alessandro Salvi ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Er Stress ◽  
Fatty Liver Disease ◽  
Molecular Mechanisms ◽  
Regulatory Element ◽  
Micro Rna ◽  
Alcoholic Fatty Liver ◽  
The Metabolic Syndrome ◽  
Alcoholic Fatty Liver Disease

Melatonin, an indole produced by pineal and extrapineal tissues, but also taken with a vegetarian diet, has strong anti-oxidant, anti-inflammatory and anti-obesogenic potentials. Non-alcoholic fatty liver disease (NAFLD) is the hepatic side of the metabolic syndrome. NAFLD is a still reversible phase but may evolve into steatohepatitis (NASH), cirrhosis and carcinoma. Currently, an effective therapy for blocking NAFLD staging is lacking. Silent information regulator 1 (SIRT1), a NAD+ dependent histone deacetylase, modulates the energetic metabolism in the liver. Micro-RNA-34a-5p, a direct inhibitor of SIRT1, is an emerging indicator of NAFLD grading. Thus, here we analyzed the effects of oral melatonin against NAFLD and underlying molecular mechanisms, focusing on steatosis, ER stress, mitochondrial shape and autophagy. Male C57BL/6J (WT) and SIRT1 heterozygous (HET) mice were placed either on a high-fat diet (58.4% energy from lard) (HFD) or on a standard maintenance diet (8.4% energy from lipids) for 16 weeks, drinking melatonin (10 mg/kg) or not. Indirect calorimetry, glucose tolerance, steatosis, inflammation, ER stress, mitochondrial changes, autophagy and microRNA-34a-5p expression were estimated. Melatonin improved hepatic metabolism and steatosis, influenced ER stress and mitochondrial shape, and promoted autophagy in WT HFD mice. Conversely, melatonin was ineffective in HET HFD mice, maintaining NASH changes. Indeed, autophagy was inconsistent in HET HFD or starved mice, as indicated by LC3II/LC3I ratio, p62/SQSTM1 and autophagosomes estimation. The beneficial role of melatonin in dietary induced NAFLD/NASH in mice was related to reduced expression of microRNA-34a-5p and sterol regulatory element-binding protein (SREBP1) but only in the presence of full SIRT1 availability.

scholarly journals Phosphorylation of eIF2α signaling pathway attenuates obesity-induced non-alcoholic fatty liver disease in an ER stress and autophagy-dependent manner

2020 ◽  
Vol 11 (12) ◽  
Author(s):  
Jie Li ◽  
Xinle Li ◽  
Daquan Liu ◽  
Shiqi Zhang ◽  
Nian Tan ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Liver Disease ◽  
Fatty Liver ◽  
Er Stress ◽  
Hepatic Steatosis ◽  
Fatty Liver Disease ◽  
Chow Diet ◽  
Dependent Manner ◽  
Alcoholic Fatty Liver ◽  
Alcoholic Fatty Liver Disease

AbstractNon-alcoholic fatty liver disease (NAFLD) is the most common liver disorder and frequently exacerbates in postmenopausal women. In NAFLD, the endoplasmic reticulum (ER) plays an important role in lipid metabolism, in which salubrinal is a selective inhibitor of eIF2α de-phosphorylation in response to ER stress. To determine the potential mechanism of obesity-induced NAFLD, we employed salubrinal and evaluated the effect of ER stress and autophagy on lipid metabolism. Ninety-five female C57BL/6 mice were randomly divided into five groups: standard chow diet, high-fat (HF) diet, HF with salubrinal, HF with ovariectomy, and HF with ovariectomy and salubrinal. All mice except for SC were given HF diet. After the 8-week obesity induction, salubrinal was subcutaneously injected for the next 8 weeks. The expression of ER stress and autophagy markers was evaluated in vivo and in vitro. Compared to the normal mice, the serum lipid level and adipose tissue were increased in obese mice, while salubrinal attenuated obesity by blocking lipid disorder. Also, the histological severity of hepatic steatosis and fibrosis in the liver and lipidosis was suppressed in response to salubrinal. Furthermore, salubrinal inhibited ER stress by increasing the expression of p-eIF2α and ATF4 with a decrease in the level of CHOP. It promoted autophagy by increasing LC3II/I and inhibiting p62. Correlation analysis indicated that lipogenesis in the development of NAFLD was associated with ER stress. Collectively, we demonstrated that eIF2α played a key role in obesity-induced NAFLD, and salubrinal alleviated hepatic steatosis and lipid metabolism by altering ER stress and autophagy through eIF2α signaling.

scholarly journals Omega-3 mechanism of action in inflammation and endoplasmic reticulum stress in mononuclear cells from overweight non-alcoholic fatty liver disease participants: study protocol for the “Brazilian Omega Study” (BROS)—a randomized controlled trial

Trials ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Ellencristina Silva Batista ◽  
Thaiane da Silva Rios ◽  
Vitor Rosetto Muñoz ◽  
Joyce Santos Jesus ◽  
Marcel Monteiro Vasconcelos ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Liver Disease ◽  
Endoplasmic Reticulum Stress ◽  
Fatty Liver ◽  
Er Stress ◽  
Fatty Liver Disease ◽  
Mononuclear Cells ◽  
Omega 3 ◽  
Alcoholic Fatty Liver ◽  
Alcoholic Fatty Liver Disease

Abstract The low-grade inflammation is pivotal in obesity and its comorbidities; however, the inflammatory proteins are out of target for traditional drug therapy. Omega-3 (ω3) fatty acids can modulate the downstream signaling of Toll-like receptor (TLR) and tumor necrosis factor-α receptor (TNFα) through GPR120, a G-protein-coupled receptor, a mechanism not yet elucidated in humans. This work aims to investigate if the ω3 supplementation, at a feasible level below the previously recommended level in the literature, is enough to disrupt the inflammation and endoplasmic reticulum stress (ER-stress), and also if in acute treatment (3 h) ω3 can activate the GPR120 in peripheral blood mononuclear cells (PBMC) and leukocytes from overweight non-alcoholic fatty liver disease (NAFLD) participants. The R270H variant of the Ffar4 (GPR120 gene) will also be explored about molecular responses and blood lipid profiles. A triple-blind, prospective clinical trial will be conducted in overweight men and women, aged 19–75 years, randomized into placebo or supplemented (2.2 g of ω3 [EPA+DHA]) groups for 28 days. For sample calculation, it was considered the variation of TNFα protein and a 40% dropout rate, obtaining 22 individuals in each group. Volunteers will be recruited among patients with NAFLD diagnosis. Anthropometric parameters, food intake, physical activity, total serum lipids, complete fatty acid blood profile, and glycemia will be evaluated pre- and post-supplementation. In the PBMC and neutrophils, the protein content and gene expression of markers related to inflammation (TNFα, MCP1, IL1β, IL6, IL10, JNK, and TAK1), ER-stress (ATF1, ATF6, IRE1, XBP1, CHOP, eIF2α, eIF4, HSP), and ω3 pathway (GPR120, β-arrestin2, Tab1/2, and TAK1) will be evaluated using Western blot and RT-qPCR. Participants will be genotyped for the R270H (rs116454156) variant using the TaqMan assay. It is hypothesized that attenuation of inflammation and ER-stress signaling pathways in overweight and NAFLD participants will be achieved through ω3 supplementation through binding to the GPR120 receptor. Trial registration ClinicalTrials.gov #RBR-7x8tbx. Registered on May 10, 2018, with the Brazilian Registry of Clinical Trials.

Vitamin D levels are not associated with non-alcoholic fatty liver disease severity in a Brazilian population

2020 ◽  
pp. 1-8
Author(s):  
Jeniffer Danielle M. Dutra ◽  
Quelson Coelho Lisboa ◽  
Silvia Marinho Ferolla ◽  
Carolina Martinelli M. L. Carvalho ◽  
Camila Costa M. Mendes ◽  
...  
Keyword(s):  
Vitamin D ◽  
Liver Disease ◽  
Fatty Liver ◽  
Disease Severity ◽  
Fatty Liver Disease ◽  
Hypovitaminosis D ◽  
Alcoholic Fatty Liver ◽  
Vitamin D Levels ◽  
The Mean ◽  
Alcoholic Fatty Liver Disease

Abstract. Some epidemiological evidence suggests an inverse correlation between non-alcoholic fatty liver disease (NAFLD) frequency and vitamin D levels. Likewise, a beneficial effect of vitamin D on diabetes mellitus (DM) and insulin resistance has been observed, but this is an unsolved issue. Thus, we aimed to investigate the prevalence of hypovitaminosis D in a NAFLD Brazilian population and its association with disease severity and presence of comorbidities. In a cross-sectional study, the clinical, biochemical and histological parameters of 139 NAFLD patients were evaluated according to two different cut-off points of serum 25-hydroxyvitamin D levels (20 ng/mL and 30 ng/mL). The mean age of the population was 56 ± 16 years, most patients were female (83%), 72% had hypertension, 88% dyslipidemia, 46% DM, 98% central obesity, and 82% metabolic syndrome. Serum vitamin D levels were < 30 ng/mL in 78% of the patients, and < 20 ng/mL in 35%. The mean vitamin D level was 24.3 ± 6.8 ng/mL. The comparison between the clinical, biochemical and histological characteristics of the patients according to the levels of vitamin D showed no significant difference. Most patients with NAFLD had hypovitaminosis D, but low vitamin D levels were not related to disease severity and the presence of comorbidities.

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