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Alzheimer's disease (AD) is the fourth leading cause of death in the United States and the most common cause of adult-onset dementia. Recent results suggest an increased prevalence and severity in African Americans compared to Caucasians. Our understanding of the potential mechanism(s) underlying this ethnicity difference is limited. We previously described ethnicity-related differences in levels of neurodegenerative proteins and cytokines/chemokines in the BA21 region of African Americans and Caucasians with AD. Here, similar multiplex assays were used to examine those endpoints in patient postmortem cerebrospinal fluid (CSF). Additionally, we measured levels of C-peptide, ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, PAI-1, resistin, and visfatin using a human diabetes 10-plex assay. The cytokine and chemokine assays revealed that levels of 26 chemokines or cytokines differed significantly with ethnicity, and three of those were significantly associated with gender. The neurodegenerative disease panel indicated that levels of soluble RAGE were significantly elevated in African Americans compared to Caucasians. All measures in the diabetes disease panel assay were significantly elevated in African Americans: ghrelin, GIP, GLP-1, glucagon, insulin, and visfatin. Through peripheral sample analysis, these results provide further evidence that ethnicity is critically involved in the manifestation of AD.
Assuntos
Doença de Alzheimer , Diabetes Mellitus , Doenças Neurodegenerativas , Adulto , Negro ou Afro-Americano , Polipeptídeo Inibidor Gástrico , Humanos , Insulina , População BrancaRESUMO
Lipids play important roles in cell signaling, energy storage, and as major structural components of cell membranes. To date, little work has been conducted to show the extent of tissue specificity of lipid compositions. Here, the recently acquired Lipidyzer platform was employed in this pilot study: (i) to assess the performance of the Lipidyzer platform, (ii) to explore lipid profiles in liver and cardiac tissue in mice, (iii) to examine sex-specific differences in lipids in the liver tissue, and (iv) to evaluate biological variances in lipidomes present in animals. In total, 787 lipid species from 13 lipid classes were measured in the liver and heart. Lipidomics data from the Lipidyzer platform were very reproducible with the coefficient of variations of the quality control (QC) samples, â¼10%. The total concentration of the cholesterol esters (CE) lipid class, and specifically CE(16:1) and CE(18:1) species, showed sex differences in the liver. Cardiac tissue had higher levels of phospholipids containing docosahexaenoic acid, which could be related to heart health status and function. Our results demonstrate the usefulness of the Lipidyzer platform in identifying differences in lipid profile at the tissue level and between male and female mice in specific tissues.
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Lipidômica , Fosfolipídeos , Animais , Membrana Celular , Feminino , Fígado , Masculino , Camundongos , Projetos PilotoRESUMO
Chronic neuroinflammation is strongly associated with AD and altered peripheral and central levels of chemokines and cytokines have been frequently described in those with AD. Given the increasing evidence of ethnicity-related differences in AD, it was of interest to determine if those altered chemokine and cytokine levels are ethnicity-related. Because African Americans exhibit a higher incidence of AD and increased symptom severity, we explored chemokine and cytokine concentrations in post-mortem brain tissue from the BA21 region of African Americans and Caucasians with AD using multiplex assays. IL-1ß, MIG, TRAIL, and FADD levels were significantly increased in African Americans while levels of IL-3 and IL-8 were significantly decreased. Those effects did not interact with gender; however, overall levels of CCL25, CCL26 and CX3CL1 were significantly decreased in women. The NLRP3 inflammasome is thought to be critically involved in AD. Increased activation of this inflammasome in African Americans is consistent with the current results.
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Doença de Alzheimer/etnologia , Doença de Alzheimer/metabolismo , Negro ou Afro-Americano/etnologia , Mediadores da Inflamação/metabolismo , Lobo Temporal/metabolismo , Negro ou Afro-Americano/genética , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/genética , Feminino , Humanos , Inflamação/etnologia , Inflamação/genética , Inflamação/metabolismo , Masculino , População Branca/etnologia , População Branca/genéticaRESUMO
Background Blockade of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a potentially attractive mechanism for lowering inflammatory and lipid risk in patients with atherosclerosis. This study aims to assess the safety, tolerability, and target engagement of MEDI6570, a high-affinity monoclonal blocking antibody to LOX-1. Methods and Results This phase 1, first-in-human, placebo-controlled study (NCT03654313) randomized 88 patients with type 2 diabetes to receive single ascending doses (10, 30, 90, 250, or 500 mg) or multiple ascending doses (90, 150, or 250 mg once monthly for 3 months) of MEDI6570 or placebo. Primary end point was safety; secondary and exploratory end points included pharmacokinetics, immunogenicity, free soluble LOX-1 levels, and change in coronary plaque volume. Mean age was 57.6/58.1 years in the single ascending doses/multiple ascending doses groups, 31.3%/62.5% were female, and mean type 2 diabetes duration was 9.7/8.7 years. Incidence of adverse events was similar among cohorts. MEDI6570 exhibited nonlinear pharmacokinetics, with terminal half-life increasing from 4.6 days (30 mg) to 11.2 days (500 mg), consistent with target-mediated drug disposition. Dose-dependent reductions in mean soluble LOX-1 levels from baseline were observed (>66% at 4 weeks and 71.61-82.96% at 10 weeks in the single ascending doses and multiple ascending doses groups, respectively). After 3 doses, MEDI6570 was associated with nonsignificant regression of noncalcified plaque volume versus placebo (-13.45 mm3 versus -8.25 mm3). Conclusions MEDI6570 was well tolerated and demonstrated dose-dependent soluble LOX-1 suppression and a pharmacokinetic profile consistent with once-monthly dosing. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT03654313.
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Diabetes Mellitus Tipo 2 , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Anticorpos Monoclonais/uso terapêutico , Lectinas/uso terapêutico , Método Duplo-Cego , Relação Dose-Resposta a DrogaRESUMO
BACKGROUND: Psoriasis is a chronic inflammatory condition associated with coronary artery disease risk. Uptake of oxidized low-density lipoprotein by the lectin-like low-density lipoprotein receptor-1 triggers release of the soluble extracellular domain of the receptor (sLOX-1). We sought to characterize the relationship between sLOX-1, inflammation, and coronary plaque progression in psoriasis. METHODS AND RESULTS: A total of 327 patients with psoriasis had serum sLOX-1 levels measured at baseline by an ELISA-based assay. Stratification by high-sensitivity C-reactive protein ≥4.0 mg/L (quartile 4), identified 81 participants who had coronary plaque phenotyping at baseline and were followed longitudinally by coronary computed tomography angiography. Subjects within high-sensitivity C-reactive protein quartile 4 were middle-aged (51.47±12.62 years), predominantly men (54.3%) with moderate psoriasis disease severity (6.60 [interquartile range, 3.30-13.40]). In the study cohort, participants with sLOX-1 above the median displayed increased vulnerable coronary plaque features. At baseline, sLOX-1 was associated with total burden (rho=0.296; P=0.01), noncalcified burden (rho=0.286; P=0.02), fibro-fatty burden (rho=0.346; P=0.004), and necrotic burden (rho=0.394; P=0.002). A strong relationship between sLOX-1, noncalcified burden (ß=0.19; P=0.03), and fibro-fatty burden (ß=0.29; P=0.003) was found in fully adjusted models at baseline and 1- and 4-year follow-up. Finally, coronary plaque features progressed over 1 year regardless of biologic or systemic treatment in subjects with high sLOX-1. CONCLUSIONS: Patients with psoriasis with both high sLOX-1 and high-sensitivity C-reactive protein levels have increased coronary plaque burden associated with atherosclerotic plaque progression independent of biologic and systemic treatment. Thus, sLOX-1 might be considered as a promising marker in coronary artery disease risk estimation beyond traditional risk factors. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01778569.
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BACKGROUND: Recent advances in high-throughput genotyping technology are paving the way for research in personalized medicine and nutrition. However, most of the genetic markers identified from association studies account for a small contribution to the total risk/benefit of the studied phenotypic trait. Testing whether the candidate genes identified by association studies are causal is critically important to the development of personalized medicine and nutrition. An efficient data mining strategy and a set of sophisticated tools are necessary to help better understand and utilize the findings from genetic association studies. DESCRIPTION: SNP (single nucleotide polymorphism) and QTL (quantitative trait locus) libraries were constructed and incorporated into ArrayTrack, with user-friendly interfaces and powerful search features. Data from several public repositories were collected in the SNP and QTL libraries and connected to other domain libraries (genes, proteins, metabolites, and pathways) in ArrayTrack. Linking the data sets within ArrayTrack allows searching of SNP and QTL data as well as their relationships to other biological molecules. The SNP library includes approximately 15 million human SNPs and their annotations, while the QTL library contains publically available QTLs identified in mouse, rat, and human. The QTL library was developed for finding the overlap between the map position of a candidate or metabolic gene and QTLs from these species. Two use cases were included to demonstrate the utility of these tools. The SNP and QTL libraries are freely available to the public through ArrayTrack at http://www.fda.gov/ArrayTrack. CONCLUSIONS: These libraries developed in ArrayTrack contain comprehensive information on SNPs and QTLs and are further cross-linked to other libraries. Connecting domain specific knowledge is a cornerstone of systems biology strategies and allows for a better understanding of the genetic and biological context of the findings from genetic association studies.
Assuntos
Pesquisa Biomédica , Genômica/métodos , Análise em Microsséries/métodos , Polimorfismo de Nucleotídeo Único , Medicina de Precisão/métodos , Locos de Características Quantitativas , Animais , Bases de Dados Genéticas , Humanos , Camundongos , Ratos , Análise de Sequência de DNARESUMO
OBJECTIVE: Scavenger receptors play crucial roles in the pathogenesis of atherosclerosis, but their role in insulin resistance has not been explored. We hypothesized that scavenger receptors are present in human adipose tissue resident macrophages, and their gene expression is regulated by adiponectin and thaizolidinediones. METHODS AND RESULTS: The gene expression of scavenger receptors including scavenger receptor-A (SRA), CD36, and lectin-like oxidized LDL receptor-1 (LOX-1) were studied in subcutaneous adipose tissue of nondiabetic subjects and in vitro. Adipose tissue SRA expression was independently associated with insulin resistance. Pioglitazone downregulated SRA gene expression in adipose tissue of subjects with impaired glucose tolerance and decreased LOX-1 mRNA in vitro. Macrophage LOX-1 expression was decreased when macrophages were cocultured with adipocytes or when exposed to adipocyte conditioned medium. Adding adiponectin neutralizing antibody resulted in a 2-fold increase in LOX-1 gene expression demonstrating that adiponectin regulates LOX-1 expression. CONCLUSIONS: Adipose tissue scavenger receptors are strongly associated with insulin resistance. Pioglitazone and adiponectin regulate gene expression of SRA and LOX-1, and this may have clinical implications in arresting the untoward sequalae of insulin resistance and diabetes, including accelerated atherosclerosis.
Assuntos
Adipócitos/efeitos dos fármacos , Hipoglicemiantes/uso terapêutico , Resistência à Insulina , Macrófagos/efeitos dos fármacos , Metformina/uso terapêutico , Obesidade/tratamento farmacológico , Receptores Depuradores/efeitos dos fármacos , Gordura Subcutânea/efeitos dos fármacos , Tiazolidinedionas/uso terapêutico , Adipócitos/metabolismo , Adiponectina/metabolismo , Adulto , Idoso , Antígenos CD36/efeitos dos fármacos , Linhagem Celular , Técnicas de Cocultura , Regulação para Baixo , Feminino , Humanos , Macrófagos/metabolismo , Masculino , Pessoa de Meia-Idade , Obesidade/metabolismo , Obesidade/fisiopatologia , Pioglitazona , RNA Mensageiro/metabolismo , Receptores Depuradores/genética , Receptores Depuradores/metabolismo , Receptores Depuradores Classe A/efeitos dos fármacos , Receptores Depuradores Classe E/efeitos dos fármacos , Gordura Subcutânea/metabolismo , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Increased adipogenesis and altered adipocyte function contribute to the development of obesity and associated comorbidities. Fructose modified adipocyte metabolism compared to glucose, but the regulatory mechanisms and consequences for obesity are unknown. Genome-wide methylation and global transcriptomics in SGBS pre-adipocytes exposed to 0, 2.5, 5, and 10 mM fructose, added to a 5-mM glucose-containing medium, were analyzed at 0, 24, 48, 96, 192, and 384 h following the induction of adipogenesis. RESULTS: Time-dependent changes in DNA methylation compared to baseline (0 h) occurred during the final maturation of adipocytes, between 192 and 384 h. Larger percentages (0.1% at 192 h, 3.2% at 384 h) of differentially methylated regions (DMRs) were found in adipocytes differentiated in the glucose-containing control media compared to adipocytes differentiated in fructose-supplemented media (0.0006% for 10 mM, 0.001% for 5 mM, and 0.005% for 2.5 mM at 384 h). A total of 1437 DMRs were identified in 5237 differentially expressed genes at 384 h post-induction in glucose-containing (5 mM) control media. The majority of them inversely correlated with the gene expression, but 666 regions were positively correlated to the gene expression. CONCLUSIONS: Our studies demonstrate that DNA methylation regulates or marks the transformation of morphologically differentiating adipocytes (seen at 192 h), to the more mature and metabolically robust adipocytes (as seen at 384 h) in a genome-wide manner. Lower (2.5 mM) concentrations of fructose have the most robust effects on methylation compared to higher concentrations (5 and 10 mM), suggesting that fructose may be playing a signaling/regulatory role at lower concentrations of fructose and as a substrate at higher concentrations.
RESUMO
CONTEXT AND OBJECTIVE: Stearoyl-coenzyme A desaturase (SCD1) is the rate-limiting enzyme that converts palmitoyl- and stearoyl-coenzyme A to palmitoleoyl- and oleoyl-cownzyme A, respectively. SCD-deficient mice are protected from obesity, and the ob/ob mouse has high levels of SCD. This study was designed to better characterize SCD1 gene and protein expression in humans with varying insulin sensitivity. DESIGN, PARTICIPANTS, AND SETTING: In a university hospital clinical research center setting, SCD1 gene expression was measured in sc adipose and vastus lateralis muscle of 86 nondiabetic subjects; 10 wk of pioglitazone (45 mg daily) and metformin (1000 mg twice daily) treatment were assessed in 36 impaired glucose-tolerant subjects. Adipocytes were treated with pioglitazone, and SCD1 expression was attenuated with small interfering RNA (siRNA) to examine other adipocyte genes. RESULTS: There was no significant relationship between adipose or muscle SCD1 mRNA and either body mass index or insulin sensitivity. After pioglitazone (but not metformin) treatment, there was a 2-fold increase in SCD1 mRNA and protein in adipose tissue. Pioglitazone also increased SCD1 in vitro. There were significant positive correlations between SCD1 and peroxisomal proliferator-activated receptor gamma (PPARgamma) as well as other PPARgamma-responsive genes, including lipin-beta, AGPAT2, RBP4, adiponectin receptors, CD68, and MCP1. When SCD1 expression was inhibited with a siRNA, lipin-beta, AGPAT2, and the adiponectin R2 receptor expression were decreased, and adipocyte MCP-1 was increased. CONCLUSIONS: SCD1 is closely linked to PPARgamma expression in humans, and is increased by PPARgamma agonists. The change in expression of some downstream PPARgamma targets after SCD1 knockdown suggests that PPARgamma up-regulation of SCD1 leads to increased lipogenesis and potentiation of adiponectin signaling.
Assuntos
Regulação Enzimológica da Expressão Gênica , Hipoglicemiantes/farmacologia , Músculo Esquelético/enzimologia , PPAR gama/fisiologia , Estearoil-CoA Dessaturase/deficiência , Estearoil-CoA Dessaturase/genética , Tiazolidinedionas/farmacologia , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/fisiologia , Adulto , Idoso , Animais , Feminino , Teste de Tolerância a Glucose , Humanos , Masculino , Metformina/farmacologia , Metformina/uso terapêutico , Camundongos , Camundongos Knockout , Camundongos Obesos , Pessoa de Meia-Idade , Músculo Esquelético/efeitos dos fármacos , Obesidade/genética , Obesidade/prevenção & controle , PPAR gama/efeitos dos fármacos , Pioglitazona , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Adulto JovemRESUMO
CONTEXT: Visfatin (VF) is a recently described adipokine preferentially secreted by visceral adipose tissue (VAT) with insulin mimetic properties. OBJECTIVE: The aim of this study was to examine the association of VF with insulin sensitivity, intramyocellular lipids (IMCL), and inflammation in humans. DESIGN AND PATIENTS: VF mRNA was examined in paired samples of VAT and abdominal sc adipose tissue (SAT) obtained from subjects undergoing surgery. Plasma VF and VF mRNA was also examined in SAT and muscle tissue, obtained by biopsy from well-characterized subjects with normal or impaired glucose tolerance, with a wide range in body mass index (BMI) and insulin sensitivity (S(I)). SETTING: The study was conducted at a University Hospital and General Clinical Research Center. INTERVENTION: S(I) was measured, and fat and muscle biopsies were performed. In impaired glucose tolerance subjects, these procedures were performed before and after treatment with pioglitazone or metformin. MAIN OUTCOME MEASURES: We measured the relationship between VF and obesity, S(I), adipose tissue inflammation, IMCL, and response to insulin sensitizers. RESULTS: No significant difference in VF mRNA was seen between SAT and VAT depots. VAT VF mRNA associated positively with BMI, whereas SAT VF mRNA decreased with BMI. SAT VF correlated positively with S(I), and the association of SAT VF mRNA with S(I) was independent of BMI. IMCL and markers of inflammation (adipose CD68 and plasma TNFalpha) were negatively associated with SAT VF. Impaired glucose tolerance subjects treated with pioglitazone showed no change in SAT VF mRNA despite a significant increase in S(I). Plasma VF and muscle VF mRNA did not correlate with BMI or S(I) or IMCL, and there was no change in muscle VF with either pioglitazone or metformin treatments. CONCLUSION: SAT VF is highly expressed in lean, more insulin-sensitive subjects and is attenuated in subjects with high IMCL, low S(I), and high levels of inflammatory markers. VAT VF and SAT VF are regulated oppositely with BMI.
Assuntos
Gordura Abdominal/imunologia , Citocinas/genética , Intolerância à Glucose/fisiopatologia , Inflamação/fisiopatologia , Resistência à Insulina/fisiologia , Obesidade/fisiopatologia , Gordura Abdominal/metabolismo , Gordura Abdominal/patologia , Biomarcadores , Biópsia , Índice de Massa Corporal , Citocinas/metabolismo , Expressão Gênica/fisiologia , Intolerância à Glucose/tratamento farmacológico , Intolerância à Glucose/imunologia , Humanos , Hipoglicemiantes/farmacologia , Inflamação/metabolismo , Metabolismo dos Lipídeos/imunologia , Metformina/farmacologia , Músculo Esquelético/imunologia , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Nicotinamida Fosforribosiltransferase , Obesidade/tratamento farmacológico , Obesidade/imunologia , Pioglitazona , RNA Mensageiro/metabolismo , Tiazolidinedionas/farmacologiaRESUMO
CONTEXT: Retinol binding protein 4 (RBP4) was recently found to be expressed and secreted by adipose tissue, and was strongly associated with insulin resistance. OBJECTIVE: The aim was to determine the relationship between RBP4 and obesity, insulin resistance, and other markers of insulin resistance in humans. DESIGN AND PATIENTS: RBP4 mRNA levels in adipose tissue and muscle of nondiabetic human subjects with either normal or impaired glucose tolerance (IGT) were studied, along with plasma RBP4. RBP4 gene expression was also measured in adipose tissue fractions, and from visceral and sc adipose tissue (SAT) from surgical patients. SETTING: The study was conducted at University Hospital and General Clinical Research Center. INTERVENTION: Insulin sensitivity (S(I)) was measured, and fat and muscle biopsies were performed. In IGT subjects, these procedures were performed before and after treatment with metformin or pioglitazone. MAIN OUTCOME MEASURES: The relationship between RBP4 expression and obesity, S(I), adipose tissue inflammation, and intramyocellular lipid level, and response to insulin sensitizers was measured. RESULTS: RBP4 was expressed predominantly from the adipocyte fraction of SAT. Although SAT RBP4 expression and the plasma RBP4 level demonstrated no significant relationship with body mass index or S(I), there was a strong positive correlation between RBP4 mRNA and adipose inflammation (monocyte chemoattractant protein-1 and CD68), and glucose transporter 4 mRNA. Treatment of IGT subjects with pioglitazone resulted in an increase in S(I) and an increase in RBP4 gene expression in both adipose tissue and muscle, but not in plasma RBP4 level, and the in vitro treatment of cultured adipocytes with pioglitazone yielded a similar increase in RBP4 mRNA. CONCLUSIONS: RBP4 gene expression in humans is associated with inflammatory markers, but not with insulin resistance. The increase in RBP4 mRNA after pioglitazone treatment is unusual, suggesting a complex regulation of this novel adipokine.
Assuntos
Intolerância à Glucose/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Resistência à Insulina/genética , Resistência à Insulina/imunologia , Proteínas de Ligação ao Retinol/genética , Tiazolidinedionas/uso terapêutico , Tecido Adiposo/fisiologia , Adulto , Antígenos CD/genética , Antígenos de Diferenciação Mielomonocítica/genética , Biomarcadores/metabolismo , Índice de Massa Corporal , Fracionamento Celular , Quimiocina CCL2/genética , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/imunologia , Intolerância à Glucose/genética , Intolerância à Glucose/imunologia , Transportador de Glucose Tipo 4/genética , Humanos , Inflamação/genética , Inflamação/imunologia , Metformina/uso terapêutico , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Obesidade/genética , Obesidade/imunologia , Pioglitazona , RNA Mensageiro/metabolismo , Proteínas de Ligação ao Retinol/metabolismo , Proteínas Plasmáticas de Ligação ao RetinolRESUMO
Lipin-alpha and -beta are the alternatively spliced gene products of the Lpin1 gene, whose product lipin is required for adipocyte differentiation. Lipin deficiency causes lipodystrophy, fatty liver, and insulin resistance in mice, whereas adipose tissue lipin overexpression results in increased adiposity but improved insulin sensitivity. To assess lipin expression and its relation to insulin resistance in humans, we examined lipin-alpha and -beta mRNA levels in subjects with normal or impaired glucose tolerance. We found higher expression levels of both lipin isoforms in lean, insulin-sensitive subjects. When compared with normal glucose-tolerant subjects, individuals with impaired glucose tolerance were more insulin resistant, demonstrated higher levels of intramyocellular lipids (IMCLs), and expressed approximately 50% lower levels of lipin-alpha and -beta. In addition, there was a strong inverse correlation between adipose tissue lipin expression and muscle IMCLs but no evidence for an increase in muscle lipid oxidation. After treatment of the impaired glucose-tolerant subjects with insulin sensitizers for 10 weeks, pioglitazone (but not metformin) resulted in a 60% increase in the insulin sensitivity index (Si) and a 32% decrease in IMCLs (both P < 0.01), along with an increase in lipin-beta (but not lipin-alpha) expression by 200% (P < 0.005). Lipin expression in skeletal muscle, however, was not related to obesity or insulin resistance. Hence, high adipose tissue lipin expression is found in insulin-sensitive subjects, and lipin-beta expression increases following treatment with pioglitazone. These results suggest that increased adipogenesis and/or lipogenesis in subcutaneous fat, mediated by the LPIN1 gene, may prevent lipotoxicity in muscle, leading to improved insulin sensitivity.
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Tecido Adiposo/metabolismo , Intolerância à Glucose/fisiopatologia , Resistência à Insulina/fisiologia , Proteínas Nucleares/biossíntese , PPAR gama/metabolismo , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Obesidade/metabolismo , Fosfatidato Fosfatase , Pioglitazona , Tiazolidinedionas/farmacologiaRESUMO
Lipid droplet proteins of the PAT (perilipin, adipophilin, and TIP47) family regulate cellular neutral lipid stores. We have studied a new member of this family, PAT-1, and found that it is expressed in highly oxidative tissues. We refer to this protein as "OXPAT." Physiologic lipid loading of mouse liver by fasting enriches OXPAT in the lipid droplet tissue fraction. OXPAT resides on lipid droplets with the PAT protein adipophilin in primary cardiomyocytes. Ectopic expression of OXPAT promotes fatty acid-induced triacylglycerol accumulation, long-chain fatty acid oxidation, and mRNAs associated with oxidative metabolism. Consistent with these observations, OXPAT is induced in mouse adipose tissue, striated muscle, and liver by physiological (fasting), pathophysiological (insulin deficiency), pharmacological (peroxisome proliferator-activated receptor [PPAR] agonists), and genetic (muscle-specific PPARalpha overexpression) perturbations that increase fatty acid utilization. In humans with impaired glucose tolerance, PPARgamma agonist treatment induces adipose OXPAT mRNA. Further, adipose OXPAT mRNA negatively correlates with BMI in nondiabetic humans. Our collective data in cells, mice, and humans suggest that OXPAT is a marker for PPAR activation and fatty acid oxidation. OXPAT likely contributes to adaptive responses to the fatty acid burden that accompanies fasting, insulin deficiency, and overnutrition, responses that are defective in obesity and type 2 diabetes.
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Ácidos Graxos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fígado/metabolismo , Ácido Palmítico/metabolismo , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Linhagem Celular , Primers do DNA , Genoma , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Células Musculares/citologia , Células Musculares/fisiologia , Miocárdio/citologia , Oxirredução , Fragmentos de Peptídeos/químicaRESUMO
BACKGROUND: Alzheimer's disease (AD) presents with an earlier onset age and increased symptom severity in African Americans and Hispanics. OBJECTIVE: Although the prevalence of plaques and tangles may not exhibit ethnicity-related differences, levels of neurodegenerative proteins have not been described. METHODS: Here, levels of five proteins (i.e., S100B, sRAGE, GDNF, Aß40, and Aß42) and the Aß42/Aß40 ratio were measured in postmortem samples of the middle temporal gyrus (BA21) from age-matched African Americans and Caucasians with AD (nâ=â6/gender/ethnicity). RESULTS: S100B levels were increased 17% in African Americans (pâ<â0.003) while sRAGE was mildly decreased (pâ<â0.09). Aß42 levels were increased 121% in African Americans (pâ<â0.02), leading to a 493% increase in the Aß42/Aß40 ratio (pâ<â0.002). Analysis of GDNF levels did not indicate any significant effects. There were no significant effects of gender and no significant ethnicity with gender interactions on any analyte. Effect size calculations indicated "medium" to "very large" effects. CONCLUSION: S100B is typically elevated in AD cases; however, the increased levels in African Americans here may be indicative of increased severity in specific populations. Increased Aß42/Aß40 ratios in the current study are compatible with increased disease severity and might indicate increased AD pathogenesis in African Americans. Overall, these results are compatible with a hypothesis of increased neuroinflammation in African Americans with AD.
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Doença de Alzheimer/etnologia , Doença de Alzheimer/patologia , Biomarcadores/metabolismo , Córtex Cerebral/metabolismo , Negro ou Afro-Americano , Idoso , Idoso de 80 Anos ou mais , Peptídeos beta-Amiloides/metabolismo , Estudos de Casos e Controles , Diagnóstico , Feminino , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Humanos , Masculino , Fragmentos de Peptídeos/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , População BrancaRESUMO
To examine the role of adipose-resident macrophages in insulin resistance, we examined the gene expression of CD68, a macrophage marker, along with macrophage chemoattractant protein-1 (MCP-1) in human subcutaneous adipose tissue using real-time RT-PCR. Both CD68 and MCP-1 mRNAs were expressed in human adipose tissue, primarily in the stromal vascular fraction. When measured in the adipose tissue from subjects with normal glucose tolerance, covering a wide range of BMI (21-51 kg/m2) and insulin sensitivity (S(I)) (0.6-8.0 x 10(-4)min(-1).microU(-1).ml(-1)), CD68 mRNA abundance, which correlated with the number of CD68-positive cells by immunohistochemistry, tended to increase with BMI but was not statistically significant. However, there was a significant inverse relation between CD68 mRNA and S(I) (r=-0.55, P=0.02). In addition, there was a strong positive relationship among adipose tissue CD68 mRNA, tumor necrosis factor-alpha (TNF-alpha) secretion in vitro (r=0.79, P<0.005), and plasma interleukin-6 (r=0.67, P < 0.005). To determine whether improving S(I) in subjects with impaired glucose tolerance (IGT) was associated with decreased CD68 expression, IGT subjects were treated for 10 weeks with pioglitazone or metformin. Pioglitazone increased S(I) by 60% and in the same subjects reduced both CD68 and MCP-1 mRNAs by >50%. Furthermore, pioglitazone resulted in a reduction in the number of CD68-positive cells in adipose tissue and reduced plasma TNF-alpha. Metformin had no effect on any of these measures. Thus, treatment with pioglitazone reduces expression of CD68 and MCP-1 in adipose tissue, apparently by reducing macrophage numbers, resulting in reduced inflammatory cytokine production and improvement in S(I).
Assuntos
Tecido Adiposo/química , Antígenos CD/genética , Antígenos de Diferenciação Mielomonocítica/genética , Quimiocina CCL2/genética , Citocinas/genética , Resistência à Insulina , Tiazolidinedionas/administração & dosagem , Adulto , Contagem de Células , Citocinas/sangue , Expressão Gênica , Humanos , Hipoglicemiantes/administração & dosagem , Macrófagos , Metformina/administração & dosagem , Pessoa de Meia-Idade , Músculos/química , Obesidade/metabolismo , Pioglitazona , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The investigation of the complex processes involved in cellular differentiation must be based on unbiased, high throughput data processing methods to identify relevant biological pathways. A number of bioinformatics tools are available that can generate lists of pathways ranked by statistical significance (i.e. by p-value), while ideally it would be desirable to functionally score the pathways relative to each other or to other interacting parts of the system or process. We describe a new computational method (Network Activity Score Finder - NASFinder) to identify tissue-specific, omics-determined sub-networks and the connections with their upstream regulator receptors to obtain a systems view of the differentiation of human adipocytes. Adipogenesis of human SBGS pre-adipocyte cells in vitro was monitored with a transcriptomic data set comprising six time points (0, 6, 48, 96, 192, 384 hours). To elucidate the mechanisms of adipogenesis, NASFinder was used to perform time-point analysis by comparing each time point against the control (0 h) and time-lapse analysis by comparing each time point with the previous one. NASFinder identified the coordinated activity of seemingly unrelated processes between each comparison, providing the first systems view of adipogenesis in culture. NASFinder has been implemented into a web-based, freely available resource associated with novel, easy to read visualization of omics data sets and network modules.
Assuntos
Adipócitos/citologia , Adipogenia , Biologia Computacional/métodos , Biologia de Sistemas , Diferenciação Celular , Simulação por Computador , Regulação da Expressão Gênica , Humanos , Internet , Fatores de Tempo , TranscriptomaRESUMO
OBJECTIVE: Micro RNAs (miRNAs) are a class of non-coding regulatory RNAs. We performed a transcriptome-wide analysis of subcutaneous adipose tissue and in vitro studies to identify miRNAs and co-regulated target transcripts associated with insulin sensitivity (SI) and obesity in human. METHODS: We selected 20 insulin-resistant (IR, SI=2.0±0.7) and 20 insulin-sensitive (IS, SI=7.2±2.3) subjects from a cohort of 117 metabolically characterized non-diabetic Caucasians for comparison. RESULTS: After global profiling, 3 miRNAs had marginally different expressions between IR and IS subjects. A total of 14 miRNAs were significantly correlated with %fat mass, body mass index (BMI), or SI. The qRT-PCR validated the correlation of miR-148a-3p with BMI (r=-0.70, P=2.73X10(-6)). MiRNA target filtering analysis identified DNA methyltransferase 1 (DNMT1) as one of the target genes of miR-148a-3p. DNMT1 expression in adipose tissue was positively correlated with BMI (r=0.47, p=8.42X10(-7)) and was inversely correlated with miR-148a-3p (r=-0.34). Differentiation of SGBS preadipocytes showed up-regulation of miR-148a-3p and down-regulation of DNMT1 in differentiated adipocytes. After transfecting miR-148a-3p mimics into HeLa-S3 cells, DNMT1 was down-regulated, while transfection of adipose stem cells with miR-148a-3p inhibitor up-regulated DNMT1. CONCLUSIONS: Our results indicate that miR-148a-3pmediated regulation of DNMT1 expression may play a mechanistic role in obesity.
Assuntos
Tecido Adiposo/metabolismo , DNA (Citosina-5-)-Metiltransferase 1/biossíntese , Regulação Enzimológica da Expressão Gênica , Resistência à Insulina , MicroRNAs/metabolismo , Obesidade/metabolismo , Tecido Adiposo/patologia , Adulto , DNA (Citosina-5-)-Metiltransferase 1/genética , Feminino , Humanos , Masculino , MicroRNAs/genética , Pessoa de Meia-Idade , Obesidade/genética , Obesidade/patologiaRESUMO
The development of obesity is becoming an international problem and the role of fructose is unclear. Studies using liver tissue and hepatocytes have contributed to the understanding of fructose metabolism. Excess fructose consumption also affects extra hepatic tissues including adipose tissue. The effects of fructose on human adipocytes are not yet fully characterized, although in vivo studies have noted increased adiposity and weight gain in response to fructose sweetened-beverages. In order to understand and predict the metabolic responses of adipocytes to fructose, this study examined differentiating and differentiated human adipocytes in culture, exposed to a range of fructose concentrations equivalent to that reported in blood after consuming fructose. A stable isotope based dynamic profiling method using [U-13C6]-d-fructose tracer was used to examine the metabolism and fate of fructose. A targeted stable isotope tracer fate association method was used to analyze metabolic fluxes and flux surrogates with exposure to escalating fructose concentration. This study demonstrated that fructose stimulates anabolic processes in adipocytes robustly, including glutamate and de novo fatty acid synthesis. Furthermore, fructose also augments the release of free palmitate from fully differentiated adipocytes. These results imply that in the presence of fructose, the metabolic response of adipocytes in culture is altered in a dose dependent manner, particularly favoring increased glutamate and fatty acid synthesis and release, warranting further in vivo studies.
RESUMO
Increased consumption of sugar and fructose as sweeteners has resulted in the utilization of fructose as an alternative metabolic fuel that may compete with glucose and alter its metabolism. To explore this, human Simpson-Golabi-Behmel Syndrome (SGBS) preadipocytes were differentiated to adipocytes in the presence of 0, 1, 2.5, 5 or 10 mM of fructose added to a medium containing 5 mM of glucose representing the normal blood glucose concentration. Targeted tracer [1,2-13C2]-d-glucose fate association approach was employed to examine the influence of fructose on the intermediary metabolism of glucose. Increasing concentrations of fructose robustly increased the oxidation of [1,2-13C2]-d-glucose to 13CO2 (p < 0.000001). However, glucose-derived 13CO2 negatively correlated with 13C labeled glutamate, 13C palmitate, and M+1 labeled lactate. These are strong markers of limited tricarboxylic acid (TCA) cycle, fatty acid synthesis, pentose cycle fluxes, substrate turnover and NAD+/NADP+ or ATP production from glucose via complete oxidation, indicating diminished mitochondrial energy metabolism. Contrarily, a positive correlation was observed between glucose-derived 13CO2 formed and 13C oleate and doses of fructose which indicate the elongation and desaturation of palmitate to oleate for storage. Collectively, these results suggest that fructose preferentially drives glucose through serine oxidation glycine cleavage (SOGC pathway) one-carbon cycle for NAD+/NADP+ production that is utilized in fructose-induced lipogenesis and storage in adipocytes.
RESUMO
Macrophages are an important component of muscle where they are involved in complex processes such as repair, regeneration and hypertrophy. We recently reported that macrophage numbers increase in the muscle of obese patients, suggesting that muscle-resident macrophages could be involved in the development of muscle insulin resistance that is associated with obesity. Coculture of activated macrophages with human muscle cells impairs insulin signaling and induces atrophy signaling pathways in the human muscle cells; this is exacerbated by the addition of palmitic acid. In this study, we tested the hypothesis that docosahexaenoic acid (DHA), a polyunsaturated fatty acid that has anti-inflammatory properties, would have the opposite effect of palmitic acid on muscle-macrophage cocultures. Surprisingly, DHA did not stimulate insulin signaling in human muscle myotubes that were cocultured with fibroblasts or macrophages. However, DHA inhibited Fn14, the TNF-like weak inducer of apoptosis receptor that increases the expression of the muscle-specific ubiquitin ligase MuRF-1 (muscle ring-finger protein-1). DHA treatment also increased the apparent molecular mass of MuRF-1 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, suggesting that DHA causes MuRF-1 to be posttranslationally modified. In conclusion, these results suggest that DHA may have a beneficial effect on muscle mass in humans by inhibiting the induction of Fn14 by infiltrating macrophages.