Salusin­α alleviates lipid metabolism disorders via regulation of the downstream lipogenesis genes through the LKB1/AMPK pathway.

Lipid metabolism disorders are a major cause of several chronic metabolic diseases which seriously affect public health. Salusin­α, a vasoactive peptide, has been shown to attenuate lipid metabolism disorders, although its mechanism of action has not been reported. To investigate the effects and potential mechanisms of Salusin­α on lipid metabolism, Salusin­α was overexpressed or knocked down using lentiviral vectors. Hepatocyte steatosis was induced by free fatty acid (FFA) after lentiviral transfection into HepG2 cells. The degree of lipid accumulation was assessed using Oil Red O staining and by measuring several biochemical indices. Subsequently, bioinformatics was used to analyze the signaling pathways that may have been involved in lipid metabolism disorders. Finally, semi­quantitative PCR and western blotting were used to verify the involvement of the liver kinase B1 (LKB1)/AMPK pathway. Compound C, an inhibitor of AMPK, was used to confirm this mechanism's involvement further. The results showed that Salusin­α significantly attenuated lipid accumulation, inflammation and oxidative stress. In addition, Salusin­α increased the levels of LKB1 and AMPK, which inhibited the expression of sterol regulatory element binding protein­1c, fatty acid synthase and acetyl­CoA carboxylase. The addition of Compound C abrogated the Salusin­α­mediated regulation of AMPK on downstream signaling molecules. In summary, overexpression of Salusin­α activated the LKB1/AMPK pathway, which in turn inhibited lipid accumulation in HepG2 cells. This provides insights into the potential mechanism underlying the mechanism by which Salusin­α ameliorates lipid metabolism disorders while identifying a potential therapeutic target.

DEAD-Box Helicase 17 exacerbates non-alcoholic steatohepatitis via transcriptional repression of cyp2c29, inducing hepatic lipid metabolism disorder and eliciting the activation of M1 macrophages.

OBJECTIVE: Our study was to elucidate the role of RNA helicase DEAD-Box Helicase 17 (DDX17) in NAFLD and to explore its underlying mechanisms. METHODS: We created hepatocyte-specific Ddx17-deficient mice aim to investigate the impact of Ddx17 on NAFLD induced by a high-fat diet (HFD) as well as methionine and choline-deficient l-amino acid diet (MCD) in adult male mice. RNA-seq and lipidomic analyses were conducted to depict the metabolic landscape, and CUT&Tag combined with chromatin immunoprecipitation (ChIP) and luciferase reporter assays were conducted. RESULTS: In this work, we observed a notable increase in DDX17 expression in the livers of patients with NASH and in murine models of NASH induced by HFD or MCD. After introducing lentiviruses into hepatocyte L02 for DDX17 knockdown or overexpression, we found that lipid accumulation induced by palmitic acid/oleic acid (PAOA) in L02 cells was noticeably weakened by DDX17 knockdown but augmented by DDX17 overexpression. Furthermore, hepatocyte-specific DDX17 knockout significantly alleviated hepatic steatosis, inflammatory response and fibrosis in mice after the administration of MCD and HFD. Mechanistically, our analysis of RNA-seq and CUT&Tag results combined with ChIP and luciferase reporter assays indicated that DDX17 transcriptionally represses Cyp2c29 gene expression by cooperating with CCCTC binding factor (CTCF) and DEAD-Box Helicase 5 (DDX5). Using absolute quantitative lipidomics analysis, we identified a hepatocyte-specific DDX17 deficiency that decreased lipid accumulation and altered lipid composition in the livers of mice after MCD administration. Based on the RNA-seq analysis, our findings suggest that DDX17 could potentially have an impact on the modulation of lipid metabolism and the activation of M1 macrophages in murine NASH models. CONCLUSION: These results imply that DDX17 is involved in NASH development by promoting lipid accumulation in hepatocytes, inducing the activation of M1 macrophages, subsequent inflammatory responses and fibrosis through the transcriptional repression of Cyp2c29 in mice. Therefore, DDX17 holds promise as a potential drug target for the treatment of NASH.

[Research progress on regulation of N6-adenylate methylation modification in lipid metabolism disorders].

Lipid metabolism is a complex physiological process, which is closely related to nutrient regulation, hormone balance and endocrine function. It involves the interactions of multiple factors and signal transduction pathways. Lipid metabolism disorder is one of the main mechanisms to induce a variety of diseases, such as obesity, diabetes, non-alcoholic fatty liver disease, hepatitis, hepatocellular carcinoma and their complications. At present, more and more studies have found that the "dynamic modification" of N6-adenylate methylation (m6A) on RNA represents a new "post-transcriptional" regulation mode. m6A methylation modification can occur in mRNA, tRNA, ncRNA, etc. Its abnormal modification can regulate gene expression changes and alternative splicing events. Many latest references have reported that m6A RNA modification is involved in the epigenetic regulation of lipid metabolism disorder. Based on the major diseases induced by lipid metabolism disorders, we reviewed the regulatory roles of m6A modification in the occurrence and development of those diseases. These overall findings inform further in-depth investigations of the underlying molecular mechanisms regarding the pathogenesis of lipid metabolism disorders from the perspective of epigenetics, and provide reference for health prevention, molecular diagnosis and treatment of related diseases.

The Causal Effects of Blood Iron and Copper on Lipid Metabolism Diseases: Evidence from Phenome-Wide Mendelian Randomization Study.

Blood levels of iron and copper, even within their normal ranges, have been associated with a wide range of clinical outcomes. The available epidemiological evidence for these associations is often inconsistent and suffers from confounding and reverse causation. This study aims to examine the causal clinical effects of blood iron and copper with Mendelian randomization (MR) analyses. Genetic instruments for the blood levels of iron and copper were curated from existing genome-wide association studies. Candidate clinical outcomes were identified based on a phenome-wide association study (PheWAS) between these genetic instruments and a wide range of phenotypes in 310,999 unrelated individuals of European ancestry from the UK Biobank. All signals passing stringent correction for multiple testing were followed by MR analyses, with replication in independent data sources where possible. We found that genetically predicted higher blood levels of iron and copper are both associated with lower risks of iron deficiency anemia (odds ratio (OR) = 0.75, 95% confidence interval (CI): 0.67-0.85, p = 1.90 × 10-6 for iron; OR = 0.88, 95% CI: 0.78-0.98, p = 0.032 for copper), lipid metabolism disorders, and its two subcategories, hyperlipidemia (OR = 0.90, 95% CI: 0.85-0.96, p = 6.44 × 10-4; OR = 0.92, 95% CI: 0.87-0.98, p = 5.51 × 10-3) and hypercholesterolemia (OR = 0.90, 95% CI: 0.84-0.95, p = 5.34 × 10-4; OR = 0.93, 95% CI: 0.89-0.99, p = 0.022). Consistently, they are also associated with lower blood levels of total cholesterol and low-density lipoprotein cholesterol. Multiple sensitivity tests were applied to assess the presence of pleiotropy and the robustness of causal estimates. Regardless of the approaches, consistent evidence was obtained. Moreover, the unique clinical effects of each blood mineral were identified. Notably, genetically predicated higher blood iron is associated with an enhanced risk of varicose veins (OR = 1.28, 95% CI: 1.15-1.42, p = 4.34 × 10-6), while blood copper is positively associated with the risk of osteoarthrosis (OR = 1.07, 95% CI: 1.02-1.13, p = 0.010). Sex-stratified MR analysis further revealed some degree of sex differences in their clinical effects. Our comparative PheWAS-MR study of iron and copper comprehensively characterized their shared and unique clinical effects, highlighting their potential causal roles in hyperlipidemia and hypercholesterolemia. Given the modifiable nature of blood mineral status and the potential for clinical intervention, these findings warrant further investigation.

Genetic characteristics and follow-up of patients with fatty acid ß-oxidation disorders through expanded newborn screening in a Northern Chinese population.

Background Fatty acid ß-oxidation disorders (FAODs) include more than 15 distinct disorders and have a wide variety of symptoms, usually not evident between episodes of acute decompensation. After the introduction of newborn screening (NBS) using tandem mass spectrometry (MS/MS), early identification of FAODs has become feasible. We analyzed the MS/MS results in Tianjin, China during a six-year period to evaluate the incidence, disease spectrum, and genetic characteristics of FAODs. Methods We analyzed the MS/MS results for screening FAODs from May 2013 to December 2018 in Tianjin, China. Infants with positive screening results were confirmed through next-generation sequencing and validated by Sanger sequencing. Results A total of 220,443 infants were screened and 25 FAODs patients were identified (1:8,817). Primary carnitine deficiency (PCD) with an incidence rate up to 1:20,040 was the most common disorder among all FAODs. Recurrent mutations of relatively common diseases, like PCD and short-chain acyl-CoA dehydrogenase deficiency (SCADD), were identified. During the follow-up, two patients suffered from sudden death due to carnitine palmitoyl transferase-Ⅱ deficiency (CPT Ⅱ) and very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD). Conclusion Our data indicated that FAODs are relatively common in Tianjin and may even cause infant death in certain cases. The elucidated disease spectrum and genetic backgrounds elucidated in this study may contribute to the treatment and prenatal genetic counseling of FAODs.

Does lifestyle contribute to disease severity in patients with inherited lipid disorders?

PURPOSE OF REVIEW: Patients with familial hypercholesterolemia, familial combined hyperlipidemia and hyperlipoprotein(a) are at high cardiovascular risk. Increasing evidence suggest that lifestyle-related risk factors such as physical inactivity, and poor diet quality could influence cardiovascular risk in these patients. Our objective is to review the evidence that supports the role of lifestyle-related factors in the prediction of cardiovascular risk in patients with inherited lipid disorders. RECENT FINDINGS: Recent studies have shown that smoking, a poor diet quality, physical inactivity, fitness levels, abdominal obesity, insulin resistance, and type 2 diabetes were associated with the presence of atherosclerosis and long-term cardiovascular outcomes in patients with familial hypercholesterolemia. Recent evidence also suggest that managing other cardiovascular risk factors such as cholesterol levels, obesity, glycemic control, blood pressure, smoking, physical inactivity, and diet quality could reduce long-term cardiovascular risk associated with hyperlipoprotein(a). Whether targeting these risk factors could ultimately decrease cardiovascular risk in these patients remains unknown. SUMMARY: Although reducing the number of atherogenic apolipoprotein-B containing particle with lipid-lowering therapy represents the cornerstone of treatment of patients with inherited lipid disorders, lifestyle-related risk factors such as physical inactivity and poor diet quality need to be targeted for the optimal management of these high-risk patients.

Hepatitis B virus inhibits apolipoprotein A5 expression through its core gene.

BACKGROUND: Hepatitis B virus (HBV) infection causes lipid metabolism disorders. Apolipoprotein A5 (ApoA5) is a new apolipoprotein family member that plays an important role in the regulation of lipid metabolism. The present study was to investigate the impact of HBV on ApoA5 expression and its regulatory mechanism. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) and western blotting were used to measure ApoA5 mRNA and protein expression in HepG2 and HepG2.2.15 cells. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum ApoA5 levels in healthy individuals and HBV patients. HBV infectious clone pHBV1.3 or individual plasmids expressing the HBV genome was cotransfected with the ApoA5 promoter pGL3-Apo5-LUC plasmid into HepG2 cells to assess the luciferase activity. RT-PCR and western blotting methods were used to detect Apo5 mRNA and protein expression, respectively. RESULTS: The ApoA5 mRNA and protein expression levels were decreased in HepG2.2.15 cells compared with the control HepG2 cells. The serum ApoA5 levels were 196.4 ± 28.7 µg/L in the healthy individuals and 104.5 ± 18.3 µg/L in the HBV patients, statistical analysis showed that the ApoA5 levels were significantly lower in HBV patients than in the healthy individuals (P < 0.05). pHBV1.3 and its core gene inhibited ApoA5 promoter activity and mRNA and protein expression in HepG2 cells. CONCLUSION: HBV inhibits ApoA5 expression at both the transcriptional and translational levels through its core gene.

A Comparison Study of Fixed and Mixed Effect Models for Gene Level Association Studies of Complex Traits.

In association studies of complex traits, fixed-effect regression models are usually used to test for association between traits and major gene loci. In recent years, variance-component tests based on mixed models were developed for region-based genetic variant association tests. In the mixed models, the association is tested by a null hypothesis of zero variance via a sequence kernel association test (SKAT), its optimal unified test (SKAT-O), and a combined sum test of rare and common variant effect (SKAT-C). Although there are some comparison studies to evaluate the performance of mixed and fixed models, there is no systematic analysis to determine when the mixed models perform better and when the fixed models perform better. Here we evaluated, based on extensive simulations, the performance of the fixed and mixed model statistics, using genetic variants located in 3, 6, 9, 12, and 15 kb simulated regions. We compared the performance of three models: (i) mixed models that lead to SKAT, SKAT-O, and SKAT-C, (ii) traditional fixed-effect additive models, and (iii) fixed-effect functional regression models. To evaluate the type I error rates of the tests of fixed models, we generated genotype data by two methods: (i) using all variants, (ii) using only rare variants. We found that the fixed-effect tests accurately control or have low false positive rates. We performed simulation analyses to compare power for two scenarios: (i) all causal variants are rare, (ii) some causal variants are rare and some are common. Either one or both of the fixed-effect models performed better than or similar to the mixed models except when (1) the region sizes are 12 and 15 kb and (2) effect sizes are small. Therefore, the assumption of mixed models could be satisfied and SKAT/SKAT-O/SKAT-C could perform better if the number of causal variants is large and each causal variant contributes a small amount to the traits (i.e., polygenes). In major gene association studies, we argue that the fixed-effect models perform better or similarly to mixed models in most cases because some variants should affect the traits relatively large. In practice, it makes sense to perform analysis by both the fixed and mixed effect models and to make a comparison, and this can be readily done using our R codes and the SKAT packages.

Higher PDCD4 expression is associated with obesity, insulin resistance, lipid metabolism disorders, and granulosa cell apoptosis in polycystic ovary syndrome.

OBJECTIVE: To investigate the expression and clinical significance of programmed cell death 4 (PDCD4), a novel metabolism-associated gene, during polycystic ovary syndrome (PCOS) pathogenesis. DESIGN: Case-control study. SETTING: University hospital. PATIENT(S): A total of 77 PCOS patients and 67 healthy women as matched controls. INTERVENTION(S): PDCD4 expression in peripheral blood mononuclear cells analyzed by quantitative real-time polymerase chain reaction, and apoptosis of granulosa cells (GCs) detected by flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and small-interfering RNA. MAIN OUTCOME MEASURE(S): PDCD4 expression, body mass index (BMI), insulin 0, insulin 120, glucose 120, homeostasis model assessment for insulin resistance (HOMA-IR), homeostasis model assessment for ß-cell function (HOMA-ß), triglycerides, high-density lipoprotein (HDL), and GC apoptosis. RESULT(S): The PCOS patients had higher PDCD4 expression, but BMI was similar as matched with the obese group, which positively correlated with BMI, insulin 0, insulin 120, glucose 120, HOMA-IR, HOMA-ß, triglycerides and negatively correlated with HDL (P<.05). After metformin treatment, PDCD4 expression was distinctly down-regulated for the obese women with PCOS with insulin resistance. Compared with the healthy controls, the apoptosis percentage of GCs was higher in the PCOS group and was decreased by knocking down PDCD4. Furthermore, expression of proapotosis factor Bax and the Bax/Bcl-2 ratio were lower, whereas the expression of antiapoptosis factor Bcl-2 was increased. In a multivariate logistic regression analysis, the level of PDCD4 expression independently related to the odds of PCOS risk after controlling for estradiol and insulin 120 (odds ratio 1.318). CONCLUSION(S): Our study suggests for the first time that higher PDCD4 expression might play an important role in PCOS pathogenesis by affecting obesity, insulin resistance, lipid metabolism disorders, and GC apoptosis.

Donor PPARα Gene Polymorphisms Influence the Susceptibility to Glucose and Lipid Disorders in Liver Transplant Recipients: A Strobe-Compliant Observational Study.

Peroxisome proliferator-activated receptor α (PPARα) is an important regulator of glucose and lipid metabolism, and is predominantly expressed in the liver. We aimed to evaluate the effect of donor hepatic PPARα gene polymorphisms on the development of metabolic disorders following liver transplantation (LT).A total of 176 patients undergoing primary LT were included in this Review Board-approved study. Genomic DNA was extracted from fresh frozen donor liver tissues (biopsy specimens for pathological testing at surgery). Eight single nucleotide polymorphisms in the PPARα gene were chosen from either the HapMap CHB database or previous reports.The distribution of metabolic disorders differed significantly between the wild-type and variant genotypes of both the rs5767743 and rs5767700 loci (P < 0.05 for all). After an adjustment for other factors (body mass index and tacrolimus blood concentration), the rs5767743 genetic variant was found to be an independent protective factor (P = 0.005, odds ratio = 0.416 per C allele, 95% confidence interval  = 0.225-0.768). When compared with the wild-type genotype, the variant genotypes rs5767743 and rs5767700 correlated with significantly increased PPARα and CYP3A4 mRNA expression and lower tacrolimus trough concentration/dose ratios (P < 0.05 for all).Donor PPARα gene polymorphisms influence the susceptibility to metabolic disorders following LT and may also be associated with a fasten tacrolimus metabolism because of elevated CYP3A4 expression.

Lipid metabolism disorders and bone dysfunction--interrelated and mutually regulated (review).

The association between lipid and bone metabolism has become an increasing focus of interest in recent years, and accumulating evidence has shown that atherosclerosis (AS) and osteoporosis (OP), a disorder of bone metabolism, frequently co-exist. Fat and bone are known to share a common progenitor cell: Multipotent mesenchymal stem cells (MSC) in the bone marrow (BM), which are able to differentiate into various cell phenotypes, including osteoblasts, adipocytes and chondrocytes. Laboratory-based and clinical trials have shown that increasing adipocytes are accompanied by a decrease in bone mineral density (BMD) and bone mass. Statins, lipid-lowering drugs used to treat hyperlipidemia, also provide benefit in the treatment of OP. There is thus evidence that the metabolism of lipids is correlated with that of bone, and that the two are mutually regulated. The present review primarily focuses on the potential association between lipid metabolism disturbance and OP, based on biological metabolism, pathophysiological processes, results from clinical and experimental animal studies, processes involved in the differentiation of adipocytes and osteoblasts, as well as pharmacological treatments of these diseases.

Impact of sterol regulatory element-binding factor-1c polymorphism on incidence of nonalcoholic fatty liver disease and on the severity of liver disease and of glucose and lipid dysmetabolism.

BACKGROUND: Genetic factors that predispose individuals to nonalcoholic fatty liver disease (NAFLD) and associated diabetes and cardiovascular disease are unclear. The transcription factor sterol regulatory element-binding protein-1c (SREBP-1c) modulates lipogenesis and insulin sensitivity and was experimentally connected to NAFLD. OBJECTIVE: We assessed the impact of a common SREBF-1c polymorphism on the incidence and severity of NAFLD and on associated glucose and lipoprotein dysmetabolism. DESIGN: We followed up 212 randomly selected, nonobese, nondiabetic, insulin-sensitive participants in a population-based study without NAFLD or metabolic syndrome at baseline who were characterized for the common SREBF-1c gene rs11868035 A/G polymorphism, dietary habits, physical activity, adipokine profile, C-reactive protein (CRP), and circulating markers of endothelial dysfunction. A comparable cohort of NAFLD patients underwent a liver biopsy, an oral-glucose-tolerance test with minimal model analysis of glucose homeostasis variables, and an oral-fat-tolerance test with measurement of plasma lipoproteins, adipokines, and cytokeratin-18 fragments. RESULTS: SREBF-1c predicted the 7-y incidence of NAFLD (OR: 1.71; 95% CI: 1.15, 2.53) and diabetes and the 7-y elevation in CRP and endothelial dysfunction markers. In biopsy-proven NAFLD patients, the SREBF-1c A allele conferred increased risk of severe steatosis and nonalcoholic steatohepatitis; more-severe hepatic, muscle, and adipose tissue insulin resistance; and pancreatic ß cell dysfunction. SREBF-1c A allele carriers also had an impaired oral fat tolerance with a postprandial accumulation of large triglyceride-rich lipoproteins and oxidized LDLs, lower HDL cholesterol and adiponectin concentrations, and cytokeratin-18 fragment elevation. CONCLUSION: SREBF-1c polymorphism is associated with increased risk of developing NAFLD with more severe liver histology and derangement in glucose and lipoprotein metabolism, which contribute to the presentation and natural history of NAFLD.

Precursor of ether phospholipids is synthesized by a flavoenzyme through covalent catalysis.

The precursor of the essential ether phospholipids is synthesized by a peroxisomal enzyme that uses a flavin cofactor to catalyze a reaction that does not alter the redox state of the substrates. The enzyme crystal structure reveals a V-shaped active site with a narrow constriction in front of the prosthetic group. Mutations causing inborn ether phospholipid deficiency, a very severe genetic disease, target residues that are part of the catalytic center. Biochemical analysis using substrate and flavin analogs, absorbance spectroscopy, mutagenesis, and mass spectrometry provide compelling evidence supporting an unusual mechanism of covalent catalysis. The flavin functions as a chemical trap that promotes exchange of an acyl with an alkyl group, generating the characteristic ether bond. Structural comparisons show that the covalent versus noncovalent mechanistic distinction in flavoenzyme catalysis and evolution relies on subtle factors rather than on gross modifications of the cofactor environment.

Adipose tissue dysfunction in humans: a potential role for the transmembrane protein ENPP1.

CONTEXT: Adipose tissue (AT) helps to regulate body fat partitioning and systemic lipid/glucose metabolism. We have recently reported lipid/glucose metabolism abnormalities and increased liver triglyceride content in an AT-selective transgenic model overexpressing ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1), the AdiposeENPP1-Tg mouse. OBJECTIVE: The aim of the study was to test the translational hypothesis that AT-ENPP1 overexpression associates with AT dysfunction (changes in AT gene expression, plasma fatty acid, and adipokine levels), increased liver triglyceride deposition, and systemic insulin resistance in humans. DESIGN/SETTING/PARTICIPANTS: A total of 134 young normoglycemic men and women were subjected to body composition studies, hyperinsulinemic-euglycemic clamps, and AT needle biopsy. Twenty men also had liver/muscle nuclear magnetic resonance spectroscopy. MAIN OUTCOME MEASURES: Predetermined measures included AT expression of ENPP1 and other lipid metabolism/inflammation genes, plasma adipokines, and nonesterified fatty acid (NEFA) levels, liver/muscle triglyceride content, and the systemic glucose disposal rate. RESULTS: After statistical adjustment for body fat content, increasing AT-ENPP1 was associated with up-regulation of genes involved in NEFA metabolism and inflammation, increased postabsorptive NEFA levels, decreased plasma adiponectin, increased liver triglyceride content, and systemic insulin resistance in men. In women, there were no changes in plasma adiponectin, NEFAs, or glucose disposal rate associated with increasing AT-ENPP1, despite increased expression of lipid metabolism and inflammation genes in AT. CONCLUSIONS: Increased AT-ENPP1 is associated with AT dysfunction, increased liver triglyceride deposition, and systemic insulin resistance in young normoglycemic men. These findings are concordant with the AdiposeENPP1-Tg phenotype and identify a potential target of therapy for health complications of AT dysfunction, including type 2 diabetes and cardiovascular disease.

Chylomicron retention disease: report of two cases from a Greek Island.

Chylomicron retention disease (CRD), or Anderson disease, is a rare, hereditary cause of fat malabsorption. It is one of the familial hypocholesterolaemia syndromes, along with homozygous hypobetalipoproteinaemia (HBL) and abetalipoproteinaemia (ABL). We report clinical, laboratory and histological data as well as molecular DNA analysis in the case of a 4-month-old boy with failure to thrive and steatorrhea who was diagnosed with CRD. His mother's first cousin, who was diagnosed as hypobetalipoproteinaemia 30 years ago, was also reviewed and his diagnosis was revised to CRD. Both patients were treated with a low fat diet and supplementation with fat-soluble vitamins resulting in significant improvement. In conclusion, CRD is a well-defined cause of fat malabsorption and can be distinguished from other forms of familial hypocholesterolaemia because of its specific lipid profile.

Adipocyte-macrophage interaction may mediate LPS-induced low-grade inflammation: potential link with metabolic complications.

Chronic low-grade infection has been suggested to be associated with metabolic disorder such as diabetes. However, the molecular mechanism underlying this important association is largely unknown. The only clue established so far is that many subjects exhibit elevated levels of C-reactive protein as measured by highly sensitive assay. Here, we hypothesized that adipocyte-macrophage interaction plays a key role in amplifying such low grade infection to the level of influencing metabolic disorders. The presence of macrophages in abdominal adipose tissues was investigated by immunohistochemistry. To see whether molecules associated with acute phase protein, LPS signaling, and persistent recruitment of monocytes, are produced at higher amounts in adipocytes co-cultured with macrophages stimulated with low concentration of LPS (1 ng/ml), we measured serum amyloid A (SAA), LPS binding protein (LBP), soluble CD14 (sCD14), and RANTES levels in culture supernatant of co-cultures. Lastly, we investigated in vivo effect of low-grade LPS infusion on the production of these molecules using obese model mice. The macrophages were certainly identified in abdominal adipose tissues. Investigated molecules, especially LBP, SAA, and RANTES were produced at higher amounts in co-cultures stimulated with LPS compared with the cells without LPS. The ob/ob, and high-fat diet-induced obesity mice produced higher amounts of LBP, SAA, and RANTES one day after LPS infusion (1 ng/ml/g body weight) compared with ob/- and normal-fat fed control mice. Thus, adipocytes and infiltrated macrophages, and their interaction with low endotoxin stimulation appear to play an important role in amplifying and maintaining LPS-induced low-grade inflammation.

Pathogenesis of lipid metabolism disorder in hepatitis C: polyunsaturated fatty acids counteract lipid alterations induced by the core protein.

BACKGROUND & AIMS: Disturbance in lipid metabolism is one of the features of chronic hepatitis C, being a crucial determinant of the progression of liver fibrosis. Experimental studies have revealed that the core protein of hepatitis C virus (HCV) induces steatosis. METHODS: The activities of fatty acid metabolizing enzymes were determined by analyzing the fatty acid compositions in HepG2 cells with or without core protein expression. RESULTS: There was a marked accumulation of triglycerides in core-expressing HepG2 cells. While the oleic/stearic acid (18:1/18:0) and palmitoleic/palmitic acid ratio (16:1/16:0) were comparable in both the core-expressing and the control cells, there was a marked accumulation of downstream product, 5,8,11-eicosatrienoic acid (20:3(n-9)) in the core-expressing HepG2 cells. The addition of eicosatetraynoic acid, which inhibits delta-6 desaturase activity which is inherently high in HepG2 cells, led to a marked accumulation of oleic and palmitoleic acids in the core-expressing cells, showing that delta-9 desaturase was activated by the core protein. Eicosapentaenoic acid (20:5(n-3)) or arachidonic acid (20:4(n-6)) administration significantly decreased delta-9 desaturase activity, the concentration of 20:3(n-9), and triglyceride accumulation. This lipid metabolism disorder was associated with NADH accumulation due to mitochondrial dysfunction, and was reversed by the addition of pyruvate through NADH utilization. CONCLUSIONS: The fatty acid enzyme, delta-9 desaturase, was activated by HCV core protein and polyunsaturated fatty acids counteracted this impact of the core protein on lipid metabolism. These results may open up new insights into the mechanism of lipid metabolism disorder associated with HCV infection and provide clues for the development of new therapeutic devices.

A Saccharomyces cerevisiae strain unable to store neutral lipids is tolerant to oxidative stress induced by α-synuclein.

Parkinson disease is a neurodegenerative pathology that has been linked to several genetic mutations of the SNCA gene encoding the pro-oxidant α-synuclein protein. The budding yeast Saccharomyces cerevisiae is a valuable model for studying the cellular and molecular mechanisms of α-synuclein toxicity. Indeed heterologous expression of α-synuclein is toxic to wild-type yeast and exhibits the main features of damage caused to mammalian neurons, including an increase in neutral lipid storage (triglycerides and steryl esters, embedded into lipid droplets). To address the significance of this accumulation, we forced α-synuclein production in a strain unable to synthesize triglycerides and steryl esters. Surprisingly, the inability to store neutral lipids rendered the cells more tolerant to α-synuclein. Our results indicate that the level of α-synuclein toxicity is correlated with fatty acid synthase activity and intracellular redox status.

[Diagnostics of moderate and high hypertriglyceridemia in patients in polyclinic practice: primary and secondary lipid metabolic disorders].

AIM: To define clinical and biochemical differences in groups of patients with moderate (< or =4.5 mmol/l and high (more than 4.5 mmol/l) blood triglyceride (TG) levels. To define the markers of biochemical and lipid parameters that could specify an algorithm for the differential diagnosis and treatment of different forms of hypertriglyceridemia. SUBJECTS AND METHODS: Patients (96 (54%) females) aged 12 to 71 years (median 50 years; quartiles, 41-61 years) with a TG level of more than 23 mmol/l and the following diseases: coronary heart disease (CHD) (44.8%), myocardial infarction (13.5%), arterial hypertension (87.9%), xanthomas (36.5%), and a family history of diseases (51%). The diagnosis of hyperlipidemia included a classical algorithm for clinical, biochemical, and clinicogenealogical examinations. Extended biochemical blood analysis, the determination of lipoprotein cholesterol (C), TG, low-density lipoprotein C, lipid electrophoresis, and assay of apolipoproteins A1, B-100, E, and C3 were made. RESULTS: The groups with moderate (< or =4.5 mmol/l and high (more than 4.5 mmol/l) blood triglycerides showed no differences in age and gender, systolic and diastolic blood pressures, the incidence of coronary heart disease, arterial hypertension, peripheral artery atherosclerosis, cardiac arrhythmias, and xanthomas. There was a significant correlation of high TG levels with smoking (a risk factor) and with the indicators of other metabolic disturbances--total C, chylomicrones, lipoprotein(a), LP-E-total, LP B:E, LP-C3-total, and LP-C3, which determined the impact of nutrition (and the development of pancreatitis), but also had a hereditary predisposition through the polygenic mechanisms of gene expression under the influence of a number of factors. CONCLUSION: Higher TG levels correlated with the parameters, the diagnosis of which makes it possible to reveal additional metabolic disturbances via environmental and polygenic mechanisms.

Neutral lipid storage disease with subclinical myopathy due to a retrotransposal insertion in the PNPLA2 gene.

An 18-year-old girl referred to a rheumatologist with malar flush and Gottran papules was found to have a markedly elevated serum CK. She was a good student and an avid ballet dancer. A muscle biopsy showed massive triglyceride storage, which was also found in peripheral blood granulocytes (Jordan anomaly) and cultured skin fibroblasts. Assessment using computerized dynamometry and cycle ergometry showed normal strength and muscle energetics, but proton spectroscopy revealed severe triglyceride accumulation in both skeletal and cardiac muscle. Sequencing of PNPLA2, the gene responsible for neutral lipid storage disease with myopathy (NLSDM), revealed a retrotransposal insertion of about 1.8kb in exon 3 that abrogates transcription of PNPLA2. The sequences of CGI-58, the gene responsible for Chanarin-Dorfman syndrome (CDS), another multisystem triglyceride storage disease, and of two genes encoding lipid droplets-associated proteins, perilipin A and adipophilin, were normal. This case shows that NLSDM can be a transposon-associated disease and that massive lipid storage in muscle can present as asymptomatic hyperCKemia.