Decreased lipid metabolism but increased FA biosynthesis are coupled with changes in liver microRNAs in obese subjects with NAFLD.

BACKGROUND/OBJECTIVE: Many controversies regarding the association of liver miRNAs with obesity and nonalcoholic fatty liver diseases (NAFLD) call for additional validations. This study sought to investigate variations in genes and hepatic miRNAs in a sample of obese patients with or without NAFLD and human hepatocytes (HH). SUBJECTS/METHODS: A total of 60 non-consecutive obese women following bariatric surgery were recruited. Subjects were classified as NAFLD (n=17), borderline (n=24) and controls (n=19) with normal enzymatic profile, liver histology and ultrasound assessments. Profiling of 744 miRNAs was performed in 8 obese women with no sign of hepatic disease and 11 NAFLD patients. Additional validation and expression of genes related to de novo fatty acid (FA) biosynthesis, uptake, transport and ß-oxidation; glucose metabolism, and inflammation was tested in the extended sample. Induction of NAFLD-related genes and miRNAs was examined in HepG2 cells and primary HH treated with palmitic acid (PA), a combination of palmitate and oleic acid, or high glucose, and insulin (HG) mimicking insulin resistance in NAFLD. RESULTS: In the discovery sample, 14 miRNAs were associated with NAFLD. Analyses in the extended sample confirmed decreased miR-139-5p, miR-30b-5p, miR-122-5p and miR-422a, and increased miR-146b-5p in obese subjects with NAFLD. Multiple linear regression analyses disclosed that NAFLD contributed independently to explain miR-139-5p (P=0.005), miR-30b-5p (P=0.005), miR-122-5p (P=0.021), miR-422a (P=0.007) and miR-146a (P=0.033) expression variance after controlling for confounders. Decreased miR-122-5p in liver was associated with impaired FA usage. Expression of inflammatory and macrophage-related genes was opposite to decreased miR-30b-5p, miR-139-5p and miR-422a, whereas increased miR-146b-5p was associated with FABP4 and decreased glucose metabolism and FA mobilization. In partial agreement, PA (but not HG) led to decreased miR-139-5p, miR-30b-5p, miR-422a and miR-146a in vitro, in parallel with increased lipogenesis and FA transport, decreased glucose metabolism and diminished FA oxidation. CONCLUSION: This study confirms decreased liver glucose and lipid metabolism but increased FA biosynthesis coupled with changes in five unique miRNAs in obese patients with NAFLD.

Neuroinflammation in obesity: circulating lipopolysaccharide-binding protein associates with brain structure and cognitive performance.

BACKGROUND/OBJECTIVES: Growing evidence implicates neuroinflammation in the pathogenesis of diet-induced obesity and cognitive dysfunction in rodent models. Obesity is associated with reduced white matter integrity and cognitive decline. Circulating lipopolysaccharide binding protein (LBP) concentration is known to be increased in patients with obesity. Here, we aimed to evaluate whether circulating LBP is associated longitudinally with white matter structure and cognitive performance according to obesity status. SUBJECTS/METHODS: This longitudinal study analyzed circulating LBP (ELISA), DTI-metrics (axial diffusivity (L1), fractional anisotropy (FA) and radial diffusivity (RD)) in specific regions of the white matter of 24 consecutive middle-aged obese subjects (13 women) and 20 healthy volunteers (10 women) at baseline and two years later. Digit Span Test (DST) was used as a measure of working memory/short-term verbal memory. RESULTS: Circulating LBP concentration was associated with FA and L1 values of several white matter regions both at baseline and follow-up. The associations remained significant after controlling for age, BMI, fat mass and plasma high sensitivity C-reactive protein. Importantly, the increase in LBP over time impacted negatively on FA and L1 values and on DST performance. CONCLUSIONS: Circulating LBP associates with brain white matter integrity and working memory/short-term verbal memory in both obese and non-obese subjects.

Circulating irisin levels and coronary heart disease: association with future acute coronary syndrome and major adverse cardiovascular events.

INTRODUCTION: Irisin is a newly discovered myokine, associated with 'browning' of the white adipose tissue, obesity, insulin resistance and metabolic syndrome. The purpose of this study is to evaluate circulating irisin as a predictor of acute coronary syndromes (ACSs) and major adverse cardiovascular events (MACE). METHODS: Sub-study 1: a case-control study, nested within the Veteran's Affairs Normative Ageing Study, evaluating circulating irisin levels in 88 ACS cases and 158 age- and sampling year-matched controls, as a predictor of ACS. Sub-study 2: a prospective cohort study, where 103 participants with established coronary artery disease were stratified by circulating irisin levels at the time they received percutaneous coronary interventions (PCIs) and were followed for the development of MACE. RESULTS: Study 1: there was no association between irisin levels and ACS in otherwise healthy individuals (odds ratio: 1.00 95% confidence interval: (0.99-1.00)). Study 2: the incidence of MACE was significantly lower in the first irisin tertile compared with the second and third (incidence rate 0 vs 0.92 (0.51-1.61) vs 0.57 (0.28-1.14) events per 1000 person-days; P < 0.01). This was primarily driven by the lower incidence of unstable angina (incidence rate 0 vs 0.61 (0.31-1.22) vs 0.43 (0.19-0.96) per 1000 person-days; P = 0.01). CONCLUSION: This is the first study to date that demonstrates that, although circulating irisin levels do not predict the development of ACS in healthy individuals, increased irisin levels are associated with the development of MACE in patients with established coronary artery disease after PCI.

CIDEC/FSP27 and PLIN1 gene expression run in parallel to mitochondrial genes in human adipose tissue, both increasing after weight loss.

OBJECTIVE: FSP27 KO mice showed enhanced expression of mitochondrial genes, increased mitochondrial activity and smaller lipid droplets. Here, we aimed to investigate lipid droplet protein (CIDEC/FSP27 and perilipinA (PLIN1)) gene expression in human adipose tissue in association with obesity, insulin resistance and mitochondrial gene expression. DESIGN AND SUBJECTS: In cohort 1, CIDEC/FSP27, PLIN1, adipogenic (FASN, ACACA, PPARG, GLUT4) and mitochondrial (PPARGC1A, PPARGC1B, TFAM, MT-CO3) gene expression were analyzed in 171 adipose tissue samples (88 visceral adipose tissue (VAT) and 83 subcutaneous adipose tissue (SAT) depots) and in a time course experiment in human subcutaneous and visceral preadipocytes using real-time PCR. In cohort 2, the effects of bariatric surgery-induced weight loss were also evaluated in six caucasian morbidly obese women. Additionally, in cohort 2 FSP27 and PLIN1 protein levels were measured using western blotting. RESULTS: CIDEC/FSP27 (1.03±0.52 vs 0.49±0.23 relative gene expression unit (R.U.), P<0.0001) and PLIN1 (1.32±0.82 vs 0.63±0.42 R.U., P<0.0001) gene were significantly more expressed in SAT than in VAT. In VAT, CIDEC/FSP27 and PLIN1 gene expression decreased with body mass index, percent fat mass, fasting glucose, fasting insulin, HOMA and were positively associated with adipogenic (PPARG, GLUT4, FASN and ACACA) and mitochondrial biogenesis (PPARGC1A, PPARGC1B, TFAM and MT-CO3)-related genes. Mitochondrial gene expression increased during adipocyte differentiation in parallel to FSP27 and PLIN1 and other adipogenic genes. After bariatric surgery-induced weight loss, PLIN1 and CIDEC/FSP27 gene and protein expression in SAT increased significantly in parallel to adipogenic and mitochondrial genes. CONCLUSION: These findings suggest a positive functional interaction between CIDEC/FSP27, PLIN1 and mitochondrial biogenesis-related genes in human adipose tissue.

Inflammation and insulin resistance exert dual effects on adipose tissue tumor protein 53 expression.

OBJECTIVE: The purpose of this study was to investigate the expression of human adipose tissue protein 53 (p53) in subjects who varied widely in terms of obesity and insulin resistance. We also analyzed different in vivo and in vitro models to try to comprehend the associations found in humans. METHODS: p53 was analyzed in human adipose and isolated adipocytes, in high fat-fed and GLP-1R KO mice, during in vitro adipogenesis, and in adipocytes after high glucose, rosiglitazone and inflammatory conditions. The effects of surgery-induced weight loss and ex vivo metformin were also evaluated. RESULTS: Omental (OM) p53 gene expression (+27%, P=0.001) and protein (+11%, P=0.04) were increased in obese subjects and high fat diet-induced obese mice (+86%, P=0.018). Although the obesity-associated inflammatory milieu was associated with increased OM p53, this was negatively related to insulin resistance and glycated hemoglobin, and positively with biomarkers for insulin sensitivity. Multiple linear regression analyses revealed that glycated hemoglobin (P<0.0001) and body mass index (P=0.048) contributed independently to explain 13.7% (P<0.0001) of the OM p53 variance. Accordingly, the improvement of insulin sensitivity with surgery-induced weight loss (+51%, P=0.01) and metformin (+42%, P=0.02) led to increased adipose p53. While the glucose-intolerant GLP-1R KO mice showed decreased mesenteric p53 (-45.4%, P=0.017), high glucose led to decreased p53 in pre-adipocytes (-27%, P<0.0001). Inflammatory treatments led to increased p53 (+35%, P<0.0001), while Rs downregulated this expression (-40%, P=0.005) in mature adipocytes. CONCLUSION: Inflammation and insulin resistance exert dual effects on adipose p53, which seems to be the final result of these opposing forces.

The lung innate immune gene surfactant protein-D is expressed in adipose tissue and linked to obesity status.

BACKGROUND: Surfactant protein-D (SFTPD) is a component of the lung innate immunity that enhances clearance of pathogens and modulates inflammatory responses. An inverse association of putative, lung-derived circulating SFTPD with obesity has been reported but no information is available concerning possible SFTPD gene expression in human adipose tissue. METHODS: SFTPD gene expression was analyzed in human omental (OM; n=156) and subcutaneous (SC; n=106) adipose tissue, and in isolated fat cells (n=12) in association with measures of obesity and glucose tolerance. RESULTS: SFTPD gene was expressed in human adipose tissue and adipocytes. This expression was decreased in OM and SC adipose tissue from obese subjects with (-47%, P<0.0001; and -37%, P=0.048) and without (-34%, P=0.001; and -22%, P=0.08; respectively) type 2 diabetes when compared with the control group. Indeed, OM SFTPD was inversely associated with body mass index (r=-0.33, P<0.0001), percent fat mass (r=-0.36, P<0.0001), waist perimeter (r=-0.26, P=0.002), diastolic blood pressure (r=-0.21, P=0.018) and fasting glucose (r=-0.21, P=0.012); and positively linked to the expression of insulin receptor substrate 1 (IRS1; r=0.25, P=0.004), perilipin A (PLIN; r=0.38, P=0.007) and fatty acid synthase (FASN; r=0.36, P<0.0001). Accordingly, increased SFTPD (4.5-fold, P=0.02) was detected in isolated adipocytes when compared with the stromal-vascular cell fraction, in parallel to IRS1, FASN and PLIN. CONCLUSIONS: Both OM and SC adipose tissue (mainly mature adipocytes) express SFTPD. This expression decreases with obesity and impaired glucose tolerance.

Liver, but not adipose tissue PEDF gene expression is associated with insulin resistance.

OBJECTIVE: Recent studies linked circulating pigment epithelium-derived factor (PEDF) to obesity-associated insulin resistance, but the main source of circulating PEDF is unknown. We aimed to investigate liver and adipose tissue PEDF gene expression in association with obesity and insulin resistance. DESIGN, SUBJECTS AND METHODS: Three (two cross-sectional and one longitudinal) independent cohorts have been studied, for adipose tissue (n=80 and n=30) and liver gene expression (n=32 and n=14). Effects of high glucose and cytokines on HepG2 cell line were also investigated. PEDF gene expression and circulating PEDF were analyzed using real-time PCR and ELISA, respectively. RESULTS: In a first cohort of subjects, PEDF relative gene expression was higher in subcutaneous (SC) than in omental (OM) adipose tissue (P<0.0001) being also higher in mature adipocytes compared with stromo-vascular cells (P<0.0001). However, OM PEDF relative gene expression was decreased in morbidly obese subjects (P=0.01). Both OM PEDF and OM PEDF receptor (PEDFR) correlated positively with lipogenic and lipolytic genes, and with genes implicated in the lipid vacuole formation. Circulating PEDF levels were not associated with fat PEDF gene expression. In the second cohort, SC PEDF was decreased in subjects with type 2 diabetes and did not change significantly after weight loss. We next explored circulating PEDF in association with markers of liver-related insulin resistance injury (alanine aminotransferase, r=0.59, P=0.001). Interestingly, liver PEDF gene expression increased with obesity and insulin resistance in men, being significantly associated with fasting glucose and glycated hemoglobin in two independent cohorts. In fact, high glucose led to increased PEDF in HepG2 cells, while inflammatory stimuli present in the adipose tissue environment downregulated PEDF. CONCLUSION: Liver, but not adipose tissue, might be the source of increased circulating PEDF linked to insulin resistance.

Thyroid hormone receptor alpha gene variants increase the risk of developing obesity and show gene-diet interactions.

OBJECTIVE: Thyroid hormone receptor-beta resistance has been associated with metabolic traits. THRA gene sequencing of an obese woman (index case) who presented as empirical thyroid hormone receptor-α (THRA) resistance, disclosed a polymorphism (rs12939700) in a critical region involved in TRα alternative processing. DESIGN AND SUBJECTS: THRA gene variants were evaluated in three independent europid populations (i) in two population cohorts at baseline (n=3417 and n=2265), 6 years later (n=2139) and (ii) in 4734 high cardiovascular risk subjects (HCVR, PREDIMED trial). RESULTS: The minor allele of the index case polymorphism (rs12939700), despite having a very low frequency (4%), was significantly associated with higher body mass index (BMI) (P=0.042) in HCVR subjects. A more frequent THRA polymorphism (rs1568400) was associated with higher BMI in subjects from the population (P=0.00008 and P=0.05) after adjusting for several confounders. Rs1568400 was also strongly associated with fasting triglycerides (P dominant=3.99 × 10(-5)). In the same sample, 6 years later, age and sex-adjusted risk of developing obesity was significantly increased in GG homozygotes (odds ratio 2.93 (95% confidence interval, 1.05-6.95)). In contrast, no association between rs1568400 and BMI was observed in HCVR subjects, in whom obesity was highly prevalent. This might be explained by the presence of an interaction (P <0.001) among the rs1568400 variant, BMI and saturated fat intake. Only when saturated fat intake was high (>24.5 g d(-1)), GG carriers showed a significantly higher BMI than A carriers after controlling for energy intake and physical activity. CONCLUSIONS: THRA gene polymorphisms are associated with obesity development. This is a novel observation linking the THRA locus to metabolic phenotypes.

Arterial hypertension diagnosis: A problem?

INTRODUCTION: Arterial hypertension (AHT), a leading risk factor in terms of attributable mortality, is a major public health problem, especially for primary care where most patients are diagnosed and followed up. Correct AHT diagnosis requires adequate theoretical knowledge and technical skills in physicians and nurses. The aim of this study was to evaluate the knowledge and skills used in initial AHT diagnosis by health professionals and to describe the factors that contribute to variability. METHODOLOGY: Cross-sectional observational study in a sample of 385 primary care physicians and nurses recruited in a Catalan health region. Using a validated questionnaire called ARC, we evaluated theoretical knowledge and analysed factors that may contribute to response variability. We also evaluated practical measurement skills using objective structured clinical examination tests. RESULTS: Medical and nursing primary care professionals had deficient knowledge and skills for initial AHT diagnosis and measurement, despite self-perceiving their knowledge to be sufficient. However, professionals who had received postgraduate or other AHT training in the previous year scored better in the ARC questionnaire. CONCLUSIONS: The results of this study point to insufficient AHT expertise to ensure quality clinical practice, suggesting that ongoing theoretical and practical training needs to be improved.

Circulating lipopolysaccharide-binding protein (LBP) as a marker of obesity-related insulin resistance.

OBJECTIVE: Lipopolysaccharide-binding protein (LBP) is a 65-kDa acute-phase protein present in blood at high concentrations, known to be derived from the liver. We aimed to gain insights into the association of circulating LBP with insulin resistance in humans and mice. METHODS, DESIGN AND MEASUREMENTS: We studied the cross-sectional (n=222) and weight loss-induced (n=34) associations of LBP (enzyme-linked immunosorbent assay) with inflammatory and metabolic parameters (including minimal model-measured insulin sensitivity), and the effects of high-fat diet (HFD), metformin and genetic insulin sensitization (glucagon-like peptide 1 receptor knockout model) in mice. RESULTS: Circulating LBP concentration was significantly increased in subjects with type 2 diabetes and dramatically increased in subjects with morbid obesity. LBP was significantly associated with insulin sensitivity and different inflammatory markers and decreased after weight loss (22.2 ± 5.8 vs 16.2 ± 9.3 µg ml(-1), P<0.0001) in association with changes in body mass index and insulin sensitivity. Circulating LBP concentration was increased in HFD mice, whereas decreased in glucagon-like peptide 1 receptor knockout mice (significantly more insulin sensitive than wild-type mice) and after metformin administration. CONCLUSION: LBP is an inflammatory marker associated with obesity-related insulin resistance.

A new validated international questionnaire on health professionals' knowledge of hypertension diagnosis.

INTRODUCTION: Arterial hypertension is the main factor in attributable mortality. It is therefore considered one of the most important public health problems. Health professionals require special training and skills to make a diagnosis. No studies have been found in the literature search that use a validated instrument (questionnaire) to assess health professionals' theoretical and practical knowledge in diagnosing hypertension or measuring blood pressure. AIM: To design and validate an instrument for gauging health professionals' theoretical knowledge in measuring blood pressure for the initial diagnosis of hypertension. METHODOLOGY: Design, development, and validation of a questionnaire in three languages (English, Spanish, and Catalan) to assess knowledge based on the Rasch-item response theory model. RESULTS: A questionnaire in three languages was constructed and validated. It consisted of 23 questions on the theoretical knowledge of the initial diagnosis of hypertension and was called the ARC questionnaire. It met all the Rasch-IRT model criteria: item- and person-fit measurement, unidimensionality, local independence, invariance, targeting, and reliability. CONCLUSIONS: The ARC questionnaire is a validated tool that enables objective and uniform analyses of knowledge in the initial diagnosis of hypertension among medical and nursing professionals, comparing them over time. It allows for established strategies to be developed to enhance this knowledge.

Telomere length of subcutaneous adipose tissue cells is shorter in obese and formerly obese subjects.

Obesity and increased fat mass are associated with increased adipocyte proliferation. Telomere length can serve as a biomarker of a cell's biological (vs chronological) age. To gain insight in the physiology of adipose tissue, we aimed to investigate telomere length in subcutaneous adipose tissue in relation to age and obesity. Telomere length was measured in 72 subcutaneous adipose tissue samples from 21 nonobese and 51 obese subjects. Telomere length of subcutaneous adipose tissue cells was negatively associated with body mass index (BMI), systolic blood pressure and fasting triglycerides. After controlling for age, fasting glucose, triglycerides and smoking status, BMI (P=0.009) contributed independently to 16% of telomere length variance. Interestingly, formerly obese patients (n=10) had shorter telomere length than never-obese subjects (n=12) of similar age, sex and BMI (7.1+/-1.3 vs 9.08+/-1.8 kb, P=0.01). In summary, adipose tissue cells from obese subjects show a shorter telomere length. The shorter telomere length of formerly obese subjects suggests that this is an established, irreversible feature of obesity that could contribute to its comorbidities.

LIGHT is associated with hypertriglyceridemia in obese subjects and increased cytokine secretion from cultured human adipocytes.

BACKGROUND: LIGHT (lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells) is a member of the tumor necrosis factor (TNF) family, primarily expressed in lymphocytes, which was associated with the induction of pro-inflammatory cytokines and alterations of lipid homeostasis in animal models. We aimed to analyze whether LIGHT has a role in the human obesity-associated inflammatory status. METHODS: The association between circulating LIGHT concentrations and clinical variables was studied in 190 subjects with different degrees of obesity and glucose tolerance. The expression and release of 21 different cytokines, and the expression of genes involved in lipid metabolism were also evaluated after stimulation with LIGHT in cultured human differentiated adipocytes. RESULTS: Serum LIGHT concentrations positively associated with body mass index (BMI), fat mass, glycated hemoglobin and fasting triglycerides, and negatively with high-density lipoprotein cholesterol. Circulating LIGHT concentrations were significantly increased in morbidly obese subjects and in patients with type 2 diabetes. LIGHT induced the secretion of several cytokines and upregulated the expression and secretion of interleukin-6 (IL-6), IL-8, Growth Regulated Oncogene (GRO) and monocyte chemotactic protein-1 (MCP-1). These observations were concomitant with the activation of nuclear factor (NF)-kappaB signalling in human differentiated adipocytes. LIGHT also upregulated the expression and synthesis of its own receptor (herpesvirus entry mediator (HVEM)) and decreased the expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and fatty acid synthase. CONCLUSION: These data suggest that LIGHT may have a role in mediating chronic inflammation and alterations of lipid metabolism in obese subjects.

Metabolic endotoxemia and saturated fat contribute to circulating NGAL concentrations in subjects with insulin resistance.

OBJECTIVE: Lipocalin-2 (neutrophil gelatinase-associated lipocalin, NGAL) is an innate immune system protein that has been linked to insulin resistance and obesity, but the mechanisms behind these associations are poorly known. We hypothesized that endotoxin (lipopolysaccharide, LPS) and fat intake were in the background of these associations. DESIGN: We studied four cohorts: (1) a cross-sectional study in 194 subjects; (2) the changes in NGAL concentration induced by diet and weight loss in 36 obese women (with circadian rhythm in 8 of them); (3) the effects of acute fat intake on circulating NGAL concentration in 42 morbidly obese subjects; and (4) LPS-induced NGAL secretion ex vivo (whole blood and adipose tissue explants). RESULTS: Serum NGAL concentration was significantly associated with fasting triglycerides and LPS-binding protein in patients with type 2 diabetes. In obese subjects, the intake of saturated fatty acids was the factor that best explained the variance of NGAL changes after weight loss (contributing independently to 14% of NGAL variance). In fact, weight loss significantly changed the circadian rhythm of NGAL. The acute increase in circulating NGAL after fat overload was significantly associated with fasting insulin (r=0.52, P<0.001), homeostasis model assessment of insulin resistance (HOMA-IR) (r=0.36, P=0.02) and post-load triglyceride concentrations (r=0.38, P=0.018). LPS-induced NGAL secretion from adipose tissue explants did not change significantly, but LPS led to a significant increase in NGAL concentration in the whole blood obtained from patients with type 2 diabetes. CONCLUSION: Metabolic endotoxemia and saturated fat might contribute to circulating NGAL concentration in patients with insulin resistance.

Thyroid hormone responsive Spot 14 increases during differentiation of human adipocytes and its expression is down-regulated in obese subjects.

CONTEXT: Very limited information is available regarding the function of human thyroid hormone responsive Spot 14 (human S14, hS14) in adipogenesis and human adiposity. OBJECTIVE: To evaluate hS14 levels during differentiation of human pre-adipocytes, in human fat depots and isolated fat cells. DESIGN: This was a cross-sectional study. SUBJECTS: A total of 161 omental (OM) and 87 subcutaneous (SC) adipose tissue samples obtained during elective surgical procedures from a population who varied widely in terms of obesity. MEASUREMENTS: hS14 gene expression and protein levels during adipogenesis were assessed by RT-PCR, western blot, and using an automated confocal imaging approach. RESULTS: hS14 gene expression levels were decreased in OM adipose tissue from overweight (-42.0%) and obese subjects (-56.5%) compared with lean subjects (P<0.05 and P<0.0001, respectively). hS14 mRNA (but not hS14-related) was inversely associated with obesity measures such as body mass index (P=0.001), percent fat mass (P=0.001), waist-to-hip ratio (P=0.020), and systolic blood pressure (P=0.031). hS14 gene expression and protein levels were up-regulated at the early stages of differentiation of human pre-adipocytes as well as for 3T3-L1 cells. That observation was most prominent in those individual cells exhibiting the more marked differentiation features. hS14 gene expression levels increased by approximately 45 000-fold in mature adipocytes. Increased hS14 levels were also found in stromal-vascular cells/pre-adipocytes (3.8-fold, P<0.05) and in adipose tissue samples (1.9-fold, P<0.0001) from SC compared with OM fat depots. CONCLUSIONS: These results suggest that hS14 is involved in human adipogenesis, but inversely related to obesity and OM fat accumulation.

Circulating osteocalcin concentrations are associated with parameters of liver fat infiltration and increase in parallel to decreased liver enzymes after weight loss.

SUMMARY: The expression of liver genes was associated with insulin action in osteocalcin knockout mice. Our findings suggest that osteocalcin may play a role in the development of insulin resistance-associated fatty liver disease. INTRODUCTION: The expression of insulin target genes was decreased in the liver of mice lacking osteocalcin. We aimed to explore the association of liver enzymes with osteocalcin. METHODS: The associations were evaluated in a cross-sectional study (266 men) and following weight loss in 28 obese subjects (nine male, 19 females). RESULTS: In the cross-sectional study, circulating osteocalcin concentration was negatively associated with alanine transaminase (ALT) (p = 0.002) and aspartate transaminase (AST) levels (p = 0.008). These associations were especially significant in non-obese subjects (n = 191). In a multiple linear regression analysis, age (p = 0.008), insulin sensitivity (p = 0.001), and osteocalcin (p = 0.04) independently contributed to 22% of ALT variance in these latter subjects. In the weight loss study, the increase in circulating osteocalcin concentration (+70.6 ± 29.3 vs. +32 ± 13.5%, p = 0.021) was significantly greater in subjects with the highest decrease in ALT levels, despite similar baseline BMI, insulin resistance and degree of weight loss than remaining subjects. In fact, the change in ALT levels were linearly associated with those of osteocalcin (r = -0.55, p = 0.003). CONCLUSIONS: In summary, our findings suggest a bone-liver axis in which osteocalcin might be the active regulator.

Lactoferrin increases (172Thr)AMPK phosphorylation and insulin-induced (p473Ser)AKT while impairing adipocyte differentiation.

OBJECTIVE: Lactoferrin is a pleiotropic glycoprotein of the innate immune system with known effects on immunomodulation and cell differentiation. To gain an insight into the interaction among obesity, inflammation and insulin action, we aimed to examine the effects of lactoferrin on adipogenesis and the response to insulin in human hepatocarcinoma (HepG2) and 3T3-L1 cell lines. DESIGN: The cells were cultured with increasing lactoferrin concentration under non-inflammatory, inflammatory and standard conditions. The response to insulin was evaluated through (473Ser)AKT phosphorylation. The effects of lactoferrin on adipogenesis were studied through the expression of different lipogenic markers, AMP-activated protein kinase (AMPK) activation, retinoblastoma (Rb) activity and Oil Red O staining in 3T3-L1 cells. RESULTS: Lactoferrin increased dose-dependent insulin-induced (473Ser)AKT phosphorylation in both cell lines. Inflammation-induced decreased (473Ser)AKT phosphorylation was also rescued by lactoferrin. In addition, lactoferrin led to increased (p172Thr)AMPK during 3T3-L1 differentiation and to decreased adipogenesis (as shown by decreased expression of fatty acid synthase, acetyl-coenzyme A carboxylase-alpha and peroxisome proliferator-activated receptor-gamma in parallel with decreased formation of lipid droplets). Lactoferrin also increased dose-dependent Rb activity (expression and hypophosphorylation) during 3T3-L1 differentiation. CONCLUSION: Lactoferrin administration increased insulin-induced (473Ser)AKT phosphorylation, even in those conditions wherein the response to insulin was downregulated, and led to blunted adipogenesis in the context of increased (p172Thr)AMPK and Rb activity.

Circulating soluble transferrin receptor concentration decreases after exercise-induced improvement of insulin sensitivity in obese individuals.

BACKGROUND: Circulating soluble transferrin receptor (sTfR) has been recently found to be associated negatively with insulin sensitivity. OBJECTIVE: To evaluate circulating sTfR concentration after changing insulin sensitivity in obese individuals. DESIGN: Circulating sTfR concentration was evaluated after diet-induced weight loss in obese women (diet (D) group, n=8); after diet-induced weight loss plus resistance training (D+RT group, n=11); and after follow-up without weight loss (control (C) group, n=7). RESULTS: After 16 weeks, insulin sensitivity (HOMA (Homeostasis Model Assessment) value) significantly improved in parallel to weight loss (-7.3%) and reduced total fat mass (evaluated using magnetic resonance imaging) in the D group. Thigh muscle mass decreased significantly (P=0.03). Serum sTfR concentration did not change significantly. In the D+RT group, weight loss (-8.7%) and improvement of insulin sensitivity were of similar magnitude. Thigh muscle mass was preserved (P=0.8). Serum sTfR concentration decreased significantly (P=0.001). Interestingly, higher the thigh muscle volume after weight loss, higher the decrease in circulating sTfR concentration. We also found that higher the increases in leg force at week 16, higher the decrease in circulating sTfR concentration in all individuals as a whole. No significant changes were observed in insulin sensitivity, sTfR concentration or thigh muscle mass in the C group. CONCLUSION: These findings suggest a long-term regulation of serum sTfR concentration by exercise-induced improvement of insulin sensitivity in obese individuals.

Cost of severe hypoglycaemia in patients with type 1 diabetes in Spain and the cost-effectiveness of insulin lispro compared with regular human insulin in preventing severe hypoglycaemia.

OBJECTIVES: To determine the costs of severe hypoglycaemia (SH) in a population of patients with type 1 diabetes mellitus in the Spanish healthcare system and the cost-effectiveness of insulin lispro over regular insulin in preventing SH episodes. METHODS: A retrospective study of 100 patients in three Spanish health centres was performed. Resource utilisation data were collected only for interventions specifically relating to the hypoglycaemic episode. The direct medical costs determined in the analyses were: costs of hospitalisation, diagnostic tests carried out, costs of treatment administered and other associated costs such as visits to the endocrinologist and re-training in glucose control, transportation and assistance of a care-giver. In addition, indirect costs such as days of lost productivity were measured. The incidence rates of SH for insulin lispro and regular insulin were obtained from the literature. The incremental cost-effectiveness of insulin lispro over regular insulin was calculated. RESULTS: The overall mean cost per episode of SH was 366 euro, comprised of 65.4% direct costs and 35.6% indirect costs. The largest cost was for hospitalisation at 183 euro per episode. The SH episodes incidence rates for 100 patients per year were 33 and 73 for insulin lispro and 48 (p < 0.05) and 117 (p < 0.01) for regular insulin, in the two clinical trials found in the literature. The additional cost to prevent one episode of SH with insulin lispro over regular insulin ranged from 277 euro to insulin lispro dominance. CONCLUSIONS: Severe hypoglycaemia has a significant impact on the total cost of diabetes. The use of insulin lispro is associated with reductions in annual costs because of SH and, possibly, the overall effect may be cost neutral or cost saving when total costs are considered. The cost of SH should be included in the analysis of total socio-economic burden of diabetes.