Effect of Dapagliflozin Versus Placebo on Symptoms and 6-Minute Walk Distance in Patients With Heart Failure: The DETERMINE Randomized Clinical Trials

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors reduce the risk of worsening heart failure (HF) and cardiovascular death in patients with HF irrespective of left ventricular ejection fraction. It is important to determine whether therapies for HF improve symptoms and functional capacity.

METHODS

The DETERMINE (Dapagliflozin Effect on Exercise Capacity Using a 6-Minute Walk Test in Patients With Heart Failure) double-blind, placebo-controlled, multicenter trials assessed the efficacy of the sodium-glucose cotransporter 2 inhibitor dapagliflozin on the Total Symptom Score (TSS) and Physical Limitation Scale (PLS) of the Kansas City Cardiomyopathy Questionnaire (KCCQ) and 6-minute walk distance (6MWD) in 313 patients with HF with reduced ejection fraction (DETERMINE-Reduced) and in 504 patients with HF with preserved ejection fraction (DETERMINE-Preserved) with New York Heart Association class II or III symptoms and elevated natriuretic peptide levels. The primary outcomes were changes in the KCCQ-TSS, KCCQ-PLS, and 6MWD after 16 weeks of treatment.

RESULTS

Among the 313 randomized patients with HF with reduced ejection fraction, the median placebo-corrected difference in KCCQ-TSS from baseline at 16 weeks was 4.2 (95% CI, 1.0, 8.2; P=0.022) in favor of dapagliflozin. The median placebo-corrected difference in KCCQ-PLS was 4.2 (95% CI, 0.0, 8.3; P=0.058). The median placebo-corrected difference in 6MWD from baseline at 16 weeks was 3.2 meters (95% CI, -6.5, 13.0; P=0.69). In the 504 patients with HF with preserved ejection fraction, the median placebo-corrected 16-week difference in KCCQ-TSS and KCCQ-PLS was 3.2 (95% CI, 0.4, 6.0; P=0.079) and 3.1 (-0.1, 5.4; P=0.23), respectively. The median 16-week difference in 6MWD was 1.6 meters (95% CI, -5.9, 9.0; P=0.67). In an exploratory post hoc analysis of both trials combined (DETERMINE-Pooled), the median placebo-corrected difference from baseline at 16 weeks was 3.7 (1.5, 5.9; P=0.005) for KCCQ-TSS, 4.0 (0.3, 4.9; P=0.036) for KCCQ-PLS, and 2.5 meters (-3.5, 8.4; P=0.50) for 6MWD.

CONCLUSIONS

Dapagliflozin improved the KCCQ-TSS in patients with HF with reduced ejection fraction but did not improve KCCQ-PLS or 6MWD. Dapagliflozin did not improve these outcomes in patients with HF with preserved ejection fraction. In a post hoc analysis including all patients across the full spectrum of ejection fraction, there was a beneficial effect of dapagliflozin on KCCQ-TSS and KCCQ-PLS but not 6MWD.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03877237 and NCT03877224.

Effects of dapagliflozin and dapagliflozin-saxagliptin on erythropoiesis, iron and inflammation markers in patients with type 2 diabetes and chronic kidney disease: data from the DELIGHT trial

BACKGROUND

This post-hoc analysis of the DELIGHT trial assessed effects of the SGLT2 inhibitor dapagliflozin on iron metabolism and markers of inflammation.

METHODS

Patients with type 2 diabetes and albuminuria were randomized to dapagliflozin, dapagliflozin and saxagliptin, or placebo. We measured hemoglobin, iron markers (serum iron, transferrin saturation, and ferritin), plasma erythropoietin, and inflammatory markers (urinary MCP-1 and urinary/serum IL-6) at baseline and week 24.

RESULTS

360/461 (78.1%) participants had available biosamples. Dapagliflozin and dapagliflozin-saxagliptin, compared to placebo, increased hemoglobin by 5.7 g/L (95%CI 4.0, 7.3; p < 0.001) and 4.4 g/L (2.7, 6.0; p < 0.001) and reduced ferritin by 18.6% (8.7, 27.5; p < 0.001) and 18.4% (8.7, 27.1; p < 0.001), respectively. Dapagliflozin reduced urinary MCP-1/Cr by 29.0% (14.6, 41.0; p < 0.001) and urinary IL-6/Cr by 26.6% (9.1, 40.7; p = 0.005) with no changes in other markers.

CONCLUSIONS

Dapagliflozin increased hemoglobin and reduced ferritin and urinary markers of inflammation, suggesting potentially important effects on iron metabolism and inflammation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02547935.

Association of Carbohydrate Antigen 125 on the Response to Dapagliflozin in Patients With Heart Failure

BACKGROUND

Elevated circulating carbohydrate antigen 125 (CA125) is a marker of congestion and a predictor of outcomes in acute heart failure (HF). Less is known about CA125 in chronic ambulatory HF with reduced ejection fraction.

OBJECTIVES

This study examined the association between baseline CA125 (and changes in CA125) and outcomes in patients with HF with reduced ejection fraction in the DAPA-HF (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure; NCT03036124) trial and its relationship with the effect of dapagliflozin.

METHODS

The primary outcome was a composite of a first episode of worsening HF or cardiovascular death. CA125 was measured at baseline and 12 months following randomization.

RESULTS

Median baseline CA125 was 13.04 U/mL (IQR: 8.78-21.13 U/mL) in 3,123 of 4,774 patients with available data. Compared with CA125 ≤35 U/mL (upper limit of normal), patients with CA125 >35 U/mL were at a higher risk of the primary outcome (adjusted HR: 1.59; 95% CI: 1.29-1.96). The adjusted risks of the primary outcome relative to quartile 1 (Q1) (≤8.78 U/mL) were as follow: Q2, 8.79-13.04 U/mL (HR: 0.94; 95% CI: 0.71-1.24); Q3, 13.05-21.13 U/mL (HR: 1.22; 95% CI: 0.94-1.59); Q4, ≥21.14 U/mL (HR: 1.63; 95% CI: 1.28-2.09). The beneficial effect of dapagliflozin compared with placebo on the primary outcome was consistent whether CA125 was analyzed in quartiles (interaction P = 0.13) or as a continuous variable (interaction P = 0.75). The placebo-corrected relative change in CA125 at 12 months was -5.2% (95% CI: -10.6% to 0.5%; P = 0.07).

CONCLUSIONS

In DAPA-HF, elevated CA125 levels were an independent predictor of the risk of worsening HF or cardiovascular death. Dapagliflozin reduced the risk of worsening HF or cardiovascular death regardless of baseline CA125.

Endothelin-1, Outcomes in Patients With Heart Failure and Reduced Ejection Fraction, and Effects of Dapagliflozin: Findings From DAPA-HF

BACKGROUND

ET-1 (endothelin-1) is implicated in the pathophysiology of heart failure and renal disease. Its prognostic importance and relationship with kidney function in patients with heart failure with reduced ejection fraction receiving contemporary treatment are uncertain. We investigated these and the efficacy of dapagliflozin according to ET-1 level in the DAPA-HF trial (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure).

METHODS

We investigated the incidence of the primary outcome (cardiovascular death or worsening heart failure), change in kidney function, and the effect of dapagliflozin according to baseline ET-1 concentration, adjusting in Cox models for other recognized prognostic variables in heart failure including NT-proBNP (N-terminal pro-B-type natriuretic peptide). We also examined the effect of dapagliflozin on ET-1 level.

RESULTS

Overall, 3048 participants had baseline ET-1 measurements of: tertile 1 (T1; ≤3.28 pg/mL; n=1016); T2 (>3.28-4.41 pg/mL; n=1022); and T3 (>4.41 pg/mL; n=1010). Patients with higher ET-1 were more likely male, more likely obese, and had lower left ventricular ejection fraction, lower estimated glomerular filtration rate, worse functional status, and higher NT-proBNP and hs-TnT (high-sensitivity troponin-T). In the adjusted Cox models, higher baseline ET-1 was independently associated with worse outcomes and steeper decline in kidney function (adjusted hazard ratio for primary outcome of 1.95 [95% CI, 1.53-2.50] for T3 and 1.36 [95% CI, 1.06-1.75] for T2; both versus T1; estimated glomerular filtration rate slope: T3, -3.19 [95% CI, -3.66 to -2.72] mL/min/1.73 m²/y, T2, -2.08 [95% CI, -2.52 to -1.63] and T1 -2.35 [95% CI, -2.79 to -1.91]; P=0.002). The benefit of dapagliflozin was consistent regardless of baseline ET-1, and the placebo-corrected decrease in ET-1 with dapagliflozin was 0.13 pg/mL (95% CI, 0.25-0.01; P=0.029).

CONCLUSIONS

Higher baseline ET-1 concentration was independently associated with worse clinical outcomes and more rapid decline in kidney function. The benefit of dapagliflozin was consistent across the range of ET-1 concentrations measured, and treatment with dapagliflozin led to a small decrease in serum ET-1 concentration.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03036124.

Relationship between endothelin-1, heart failure with reduced ejection fraction and dapagliflozin: findings from DAPA-HF

Background

Circulating Endothelin-1 (ET-1) is associated with heart failure (HF) severity and has also been widely implicated in the pathophysiology of renal disease. However, its prognostic importance and relationship with kidney function in patients with HFrEF receiving contemporary treatment is uncertain.

Purpose

To investigate the association of ET-1 with heart failure outcomes, as well as change in kidney function; and the efficacy of dapagliflozin according to baseline serum ET-1 in the Dapagliflozin And Prevention of Adverse outcomes in Heart Failure trial (DAPA-HF).

Methods

Serum ET-1 was measured at randomization and at 12 months and analysed using a Microfluidics immunoassay. We investigated the incidence of the primary outcome (cardiovascular death or worsening HF), and analysed change in kidney function according to tertile of baseline ET-1 concentration. Additionally, we assessed whether baseline ET-1 modified the treatment effect of dapagliflozin.

Results

Of 4744 randomized participants, 3048 (64.2%) had a baseline ET-1 measurement: tertile 1 (≤3.28 pg/mL, n=1016), tertile 2 (&gt;3.28 to 4.41 pg/mL, n=1022), and tertile 3 (&gt;4.41 pg/mL, n=1010). Patients with higher baseline ET-1 concentrations were more likely male, obese and to have lower LVEF, lower eGFR, worse functional status, and elevated NT-proBNP and high-sensitivity troponin-T.

Adjusting for other predictive variables including NT-proBNP, higher baseline ET-1 was independently associated with worse outcomes and steeper decline in kidney function: adjusted hazard ratio (aHR) for the primary outcome of 1.95 (1.53–2.50) for tertile 3 and 1.36 (95% CI 1.06–1.75) for tertile 2; aHR for worsening HF of 2.54 (1.82–3.53) for tertile 3 and 1.54 (1.10–2.18) for tertile 2; aHR for cardiovascular death of 1.39 (1.01–1.92) for tertile 3 and 1.13 (0.82–1.57) for tertile 2; and eGFR slope −3.19 (95% CI −3.66 to −2.72) mL/min/1.73 m2 per year in tertile 3 versus −2.06 (−2.51 to −1.62) in tertile 2 and −2.35 (−2.79 to −1.91) in tertile 1, p for difference (eGFR slope)=0.002.

The benefit of dapagliflozin was consistent regardless of baseline ET-1, whether analysed according to tertiles or as a continuous variable, with p-interaction for primary outcome 0.47 and 0.10 respectively. Compared to placebo, there was a trend to reduction in ET-1 level at 12 months with dapagliflozin (difference −0.12 pg/mL, p-value=0.07).

Conclusions

Baseline ET-1 concentration was independently associated with clinical outcomes and with more rapid decline in kidney function. The benefit of dapagliflozin was consistent across the range of ET-1 concentrations measured.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The DAPA-HF trial was funded by AstraZeneca. Professor John McMurray is supported by a British Heart Foundation Centre of Research Excellence Grant RE/18/6/34217.

Outcomes related to IGFBP-7 in patients with heart failure and reduced ejection fraction and effects of dapagliflozin: findings from DAPA-HF

Introduction

Insulin-like growth factor binding protein 7 (IGFBP-7) has been proposed as a novel prognostic biomarker in heart failure, but the association between IGFBP-7 and cardiovascular outcomes has not been examined in a large cohort of patients with heart failure and reduced ejection fraction (HFrEF).

Purpose

In this post-hoc analysis of the Dapagliflozin And Prevention of Adverse outcomes in Heart Failure trial (DAPA-HF) we examined the relationship between plasma IGFBP-7 level and outcomes in patients with HFrEF, the effect of dapagliflozin according to IGFBP-7 level and change in IGFBP-7 at 12 months.

Methods

Patients in NYHA class II–IV with LVEF ≤40% and elevated NT-proBNP were included in DAPA-HF. Participants were randomly allocated to dapagliflozin 10mg or matching placebo. In this analysis, patients were categorized by IGFBP-7 tertile. The primary outcome was a composite of cardiovascular death or worsening HF event; secondary outcomes were components of the primary outcome and all-cause mortality. The risk of each outcome was compared across thirds of IGFBP-7 using Cox regression models with adjustment for NT-proBNP and high-sensitivity troponin T as well as: randomised treatment, age, sex, race, region, systolic blood pressure, heart rate, ejection fraction, estimated glomerular filtration rate, NYHA class, history of HF hospitalisation, ischaemic aetiology of HF, hypertension, stroke, atrial fibrillation, prior MI and stratified by diabetes status. The efficacy of dapagliflozin was assessed according to baseline IGFBP-7 level. Change in IGFBP-7 at 12 months was assessed using the ratio of geometric means.

Results

3158 patients had measurement of IGFBP-7 at baseline. The median value of IGFBP-7 was 192 ng/mL (interquartile range 158–246). Patients in the highest third of IGFBP-7 levels had more advanced HF, with higher NYHA class and NT-proBNP, had worse renal function and more type 2 diabetes. Patients in the highest third had the highest rate of the primary outcome (Figure 1). The adjusted hazard ratio (aHR) for the primary endpoint (with lowest third of IGFBP-7 as reference) was 0.94 (95% CI 0.74–1.20) for middle third and 1.49 (95% CI 1.17–1.89) for top third. The corresponding aHRs for worsening HF event were 0.99 (95% CI 0.72–1.36) for middle third and 1.84 (95% CI 1.35–2.50) for top third. Cardiovascular and all-cause mortality did not vary by IGFBP-7 tertile. The benefit of dapagliflozin was consistent regardless of baseline IGFBP-7 (p for interaction for primary endpoint = 0.34). The change in IGFBP-7 from baseline to 12 months did not differ between placebo and dapagliflozin.

Conclusions

Elevation of IGFBP-7 in patients with HFrEF was associated with more adverse HF outcomes, even after adjustment for both NT-proBNP and hsTnT. The treatment benefit of dapagliflozin did not vary by baseline IGFBP-7.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The DAPA-HF trial was funded by AstraZeneca.CA and JJVM are supported by a British Heart Foundation Centre of Research Excellence Grant.

Iron Deficiency in Heart Failure and Effect of Dapagliflozin: Findings From DAPA-HF

BACKGROUND

Iron deficiency is common in heart failure and associated with worse outcomes. We examined the prevalence and consequences of iron deficiency in the DAPA-HF trial (Dapagliflozin and Prevention of Adverse-Outcomes in Heart Failure) and the effect of dapagliflozin on markers of iron metabolism. We also analyzed the effect of dapagliflozin on outcomes, according to iron status at baseline.

METHODS

Iron deficiency was defined as a ferritin level <100 ng/mL or a transferrin saturation <20% and a ferritin level 100 to 299 ng/mL. Additional biomarkers of iron metabolism, including soluble transferrin receptor, erythropoietin, and hepcidin were measured at baseline and 12 months after randomization. The primary outcome was a composite of worsening heart failure (hospitalization or urgent visit requiring intravenous therapy) or cardiovascular death.

RESULTS

Of the 4744 patients randomized in DAPA-HF, 3009 had ferritin and transferrin saturation measurements available at baseline, and 1314 of these participants (43.7%) were iron deficient. The rate of the primary outcome was higher in patients with iron deficiency (16.6 per 100 person-years) compared with those without (10.4 per 100 person-years; P<0.0001). The effect of dapagliflozin on the primary outcome was consistent in iron-deficient compared with iron-replete patients (hazard ratio, 0.74 [95% CI, 0.58-0.92] versus 0.81 [95% CI, 0.63-1.03]; P-interaction=0.59). Similar findings were observed for cardiovascular death, heart failure hospitalization, and all-cause mortality. Transferrin saturation, ferritin, and hepcidin were reduced and total iron-binding capacity and soluble transferrin receptor increased with dapagliflozin compared with placebo.

CONCLUSIONS

Iron deficiency was common in DAPA-HF and associated with worse outcomes. Dapagliflozin appeared to increase iron use but improved outcomes, irrespective of iron status at baseline.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03036124.

Effects of dapagliflozin on volume status and systemic haemodynamics in patients with chronic kidney disease without diabetes: Results from DAPASALT and DIAMOND

AIMS

To assess the effect of sodium-glucose cotransporter-2 inhibitor dapagliflozin on natriuresis, blood pressure (BP) and volume status in patients with chronic kidney disease (CKD) without diabetes.

MATERIALS AND METHODS

We performed a mechanistic open-label study (DAPASALT) to evaluate the effects of dapagliflozin on 24-hour sodium excretion, 24-hour BP, extracellular volume, and markers of volume status during a standardized sodium diet (150 mmol/d) in six patients with CKD. In parallel, in a placebo-controlled double-blind crossover trial (DIAMOND), we determined the effects of 6 weeks of dapagliflozin on markers of volume status in 53 patients with CKD.

RESULTS

In DAPASALT (mean age 65 years, mean estimated glomerular filtration rate [eGFR] 39.4 mL/min/1.73 m² , median urine albumin:creatinine ratio [UACR] 111 mg/g), dapagliflozin did not change 24-hour sodium and volume excretion during 2 weeks of treatment. Dapagliflozin was associated with a modest increase in 24-hour glucose excretion on Day 4, which persisted at Day 14 and reversed to baseline after discontinuation. Mean 24-hour systolic BP decreased by -9.3 (95% confidence interval [CI] -19.1, 0.4) mmHg after 4 days and was sustained at Day 14 and at wash-out. Renin, angiotensin II, urinary aldosterone and copeptin levels increased from baseline. In DIAMOND (mean age 51 years, mean eGFR 59.0 mL/min/1.73 m² , median UACR 608 mg/g), compared to placebo, dapagliflozin increased plasma renin (38.5 [95% CI 7.4, 78.8]%), aldosterone (19.1 [95% CI -5.9, 50.8]%), and copeptin levels (7.3 [95% CI 0.1, 14.5] pmol/L).

CONCLUSIONS

During a standardized sodium diet, dapagliflozin decreased BP but did not increase 24-hour sodium and volume excretion. The lack of increased natriuresis and diuresis may be attributed to activation of intra-renal compensatory mechanisms to prevent excessive water loss.

The adaptive renal response for volume homeostasis during two weeks of dapagliflozin treatment in people with type 2 diabetes and preserved renal function on a sodium-controlled diet

Introduction

Proximal tubule sodium uptake is diminished following sodium glucose cotransporter 2 (SGLT2) inhibition. We previously showed that during SGLT2 inhibition, the kidneys adapt by increasing sodium uptake at distal tubular segments, thereby maintaining body sodium balance. Despite continuous glycosuria, we detected no increased urine volumes. We therefore assessed the adaptive renal responses to prevent excessive fluid loss.

Methods

We conducted a mechanistic open-label study in people with type 2 diabetes mellitus with preserved kidney function, who received a standardized sodium intake (150 mmol/d) to evaluate the effects of dapagliflozin on renin-angiotensin-aldosterone system (RAAS) hormones, volume-related biomarkers, urinary albumin-to-creatinine ratio (UACR), and estimated glomerular filtration rate (eGFR), at start of treatment (day 4), end of treatment (day 14), and follow-up (day 18).

Results

A total of 14 people were enrolled. Plasma renin and angiotensin II and urinary aldosterone and angiotensinogen were acutely and persistently increased during treatment with dapagliflozin. Plasma copeptin level was numerically increased after 4 days (21%). Similarly, fractional urea excretion was significantly decreased at start of treatment (−17%). Free water clearance was significantly decreased after 4 days (−74%) and 14 days (−41%). All changes reversed after dapagliflozin discontinuation.

Conclusion

Dapagliflozin-induced osmotic diuresis triggers kidney adaptive mechanisms to maintain volume and sodium balance in people with type 2 diabetes and preserved kidney function. ClinicalTrials.gov (identification: NCT03152084).

Dapagliflozin reduces uric acid concentration, an independent predictor of adverse outcomes in DAPA‐HF

Aims

Blood uric acid (UA) levels are frequently elevated in patients with heart failure and reduced ejection fraction (HFrEF), may lead to gout and are associated with worse outcomes. Reduction in UA is desirable in HFrEF and sodium–glucose cotransporter 2 inhibitors may have this effect. We aimed to examine the association between UA and outcomes, the effect of dapagliflozin according to baseline UA level, and the effect of dapagliflozin on UA in patients with HFrEF in the DAPA‐HF trial.

Methods and results

The association between UA and the primary composite outcome of cardiovascular death or worsening heart failure, its components, and all‐cause mortality was examined using Cox regression analyses among 3119 patients using tertiles of UA, after adjustment for other prognostic variables. Change in UA from baseline over 12 months was also evaluated. Patients in tertile 3 (UA ≥6.8 mg/dl) versus tertile 1 (<5.4 mg/dl) were younger (66.3 ± 10.8 vs. 68 ± 10.2 years), more often male (83.1% vs. 71.5%), had lower estimated glomerular filtration rate (58.2 ± 17.4 vs. 70.6 ± 18.7 ml/min/1.73 m²), and more often treated with diuretics. Higher UA was associated with a greater risk of the primary outcome (adjusted hazard ratio tertile 3 vs. tertile 1: 1.32, 95% confidence interval [CI] 1.06–1.66; p = 0.01). The risk of heart failure hospitalization and cardiovascular death increased by 7% and 6%, respectively per 1 mg/dl unit increase of UA (p = 0.04 and p = 0.07). Spline analysis revealed a linear increase in risk above a cut‐off UA value of 7.09 mg/dl. Compared with placebo, dapagliflozin reduced UA by 0.84 mg/dl (95% CI −0.93 to −0.74) over 12 months (p < 0.001). Dapagliflozin improved outcomes, irrespective of baseline UA concentration.

Conclusion

Uric acid remains an independent predictor of worse outcomes in a well‐treated contemporary HFrEF population. Compared with placebo, dapagliflozin reduced UA and improved outcomes irrespective of UA concentration.

Serial Assessment of High-Sensitivity Cardiac Troponin and the Effect of Dapagliflozin in Patients with Heart Failure with Reduced Ejection Fraction: An Analysis of the DAPA-HF Trial

Background: Circulating high-sensitivity cardiac troponin T (hsTnT) predominantly reflects myocardial injury, and higher levels are associated with a higher risk of worsening heart failure (HF) and death in patients with HF with reduced ejection fraction (HFrEF). Less is known about the prognostic significance of changes in hsTnT over time, the effects of dapagliflozin on clinical outcomes in relation to baseline hsTnT levels, and the effect of dapagliflozin on hsTnT levels. Methods: DAPA-HF was a randomized, double-blind, placebo-controlled trial of dapagliflozin (10 mg daily) in patients with NYHA class II-IV symptoms and left ventricular ejection fraction ≤40% (median follow-up = 18.2 months). hsTnT (Roche Diagnostics) was measured at baseline in 3,112 patients and at 1 year in 2,506 patients. The primary endpoint was adjudicated worsening HF or cardiovascular death. Clinical endpoints were analyzed according to baseline hsTnT and change in hsTnT from baseline to 1 year. Comparative treatment effects on clinical endpoints with dapagliflozin vs. placebo were assessed by baseline hsTnT. The effect of dapagliflozin on hsTnT was explored. Results: Median baseline hsTnT concentration was 20.0 (25th-75th percentile, 13.7 to 30.2) ng/L. Over 1 year, 67.9% of patients had a ≥10% relative increase or decrease in hsTnT concentrations, and 43.5% had a ≥20% relative change. A stepwise gradient of higher risk for the primary endpoint was observed across increasing quartiles of baseline hsTnT concentration (adjusted hazard ratio [aHR] Q4 vs. Q1, 5.10; 95% CI, 3.67-7.08). Relative and absolute increases in hsTnT over 1 year were associated with higher subsequent risk of the primary endpoint. The relative reduction in the primary endpoint with dapagliflozin was consistent across quartiles of baseline hsTnT (p-interaction = 0.55), but patients in the top quartile tended to have the greatest absolute risk reduction (absolute risk difference, 7.5%; 95% CI, 1.0% - 14.0%). Dapagliflozin tended to attenuate the increase in hsTnT over time compared to placebo (relative least squares mean reduction, -3% [-6% to 0%]; p=0.076). Conclusions: Higher baseline hsTnT and greater increase in hsTnT over 1 year are associated with worse clinical outcomes. Dapagliflozin consistently reduced the risk of the primary endpoint, irrespective of baseline hsTnT levels. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique Identifier: NCT03036124.

Genome-wide association study of circulating interleukin 6 levels identifies novel loci

Interleukin 6 (IL-6) is a multifunctional cytokine with both pro- and anti-inflammatory properties with a heritability estimate of up to 61%. The circulating levels of IL-6 in blood have been associated with an increased risk of complex disease pathogenesis. We conducted a two-staged, discovery and replication meta genome-wide association study (GWAS) of circulating serum IL-6 levels comprising up to 67 428 (ndiscovery = 52 654 and nreplication = 14 774) individuals of European ancestry. The inverse variance fixed effects based discovery meta-analysis, followed by replication led to the identification of two independent loci, IL1F10/IL1RN rs6734238 on chromosome (Chr) 2q14, (Pcombined = 1.8 × 10-11), HLA-DRB1/DRB5 rs660895 on Chr6p21 (Pcombined = 1.5 × 10-10) in the combined meta-analyses of all samples. We also replicated the IL6R rs4537545 locus on Chr1q21 (Pcombined = 1.2 × 10-122). Our study identifies novel loci for circulating IL-6 levels uncovering new immunological and inflammatory pathways that may influence IL-6 pathobiology.

Adult mice are unresponsive to AAV8-Gremlin1 gene therapy targeting the liver

Objective

Gremlin 1 (GREM1) is a secreted BMP2/4 inhibitor which regulates commitment and differentiation of human adipose precursor cells and prevents the browning effect of BMP4. GREM1 is an insulin antagonist and serum levels are high in type 2 diabetes (T2D). We here examined in vivo effects of AAV8 (Adeno-Associated Viral vectors of serotype eight) GREM 1 targeting the liver in mature mice to increase its systemic secretion and also, in a separate study, injected recombinant GREM 1 intraperitoneally. The objective was to characterize systemic effects of GREM 1 on insulin sensitivity, glucose tolerance, body weight, adipose cell browning and other local tissue effects.

Methods

Adult mice were injected with AAV8 vectors expressing GREM1 in the liver or receiving regular intra-peritoneal injections of recombinant GREM1 protein. The mice were fed with a low fat or high fat diet (HFD) and followed over time.

Results

Liver-targeted AAV8-GREM1 did not alter body weight, whole-body glucose and insulin tolerance, or adipose tissue gene expression. Although GREM1 protein accumulated in liver cells, GREM1 serum levels were not increased suggesting that it may not have been normally processed for secretion. Hepatic lipid accumulation, inflammation and fibrosis were also not changed. Repeated intraperitoneal rec-GREM1 injections for 5 weeks were also without effects on body weight and insulin sensitivity. UCP1 was slightly but significantly reduced in both white and brown adipose tissue but this was not of sufficient magnitude to alter body weight. We validated that recombinant GREM1 inhibited BMP4-induced pSMAD1/5/9 in murine cells in vitro, but saw no direct inhibitory effect on insulin signalling and pAkt (ser 473 and thr 308) activation.

Conclusion

GREM1 accumulates intracellularly when overexpressed in the liver cells of mature mice and is apparently not normally processed/secreted. However, also repeated intraperitoneal injections were without effects on body weight and insulin sensitivity and adipose tissue UCP1 levels were only marginally reduced. These results suggest that mature mice do not readily respond to GREMLIN 1 but treatment of murine cells with GREMLIN 1 protein in vitro validated its inhibitory effect on BMP4 signalling while insulin signalling was not altered.

Natriuretic Effect of Two Weeks of Dapagliflozin Treatment in Patients With Type 2 Diabetes and Preserved Kidney Function During Standardized Sodium Intake: Results of the DAPASALT Trial

OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk for heart failure hospitalization potentially by inducing sodium excretion, osmotic diuresis, and plasma volume contraction. Few studies have investigated this hypothesis, but none have assessed cumulative sodium excretion with SGLT2 inhibition during standardized sodium intake in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The DAPASALT trial was a mechanistic, nonrandomized, open-label study in patients with type 2 diabetes with preserved kidney function on a controlled standardized sodium diet (150 mmol/day). It evaluated the effects of dapagliflozin on sodium excretion, 24-h blood pressure, and extracellular, intracellular, and plasma volumes at the start of treatment (ST) (days 2-4), end of treatment (ET) (days 12-14), and follow-up (FU) (days 15-18).

RESULTS

Fourteen patients were included in the efficacy analysis. Mean (SD) baseline sodium excretion (150 [32] mmol/24-h) did not significantly change during treatment (change at ST: -7.0 mmol/24-h [95% CI -22.4, 8.4]; change at ET: 2.1 mmol/24-h [-28.8, 33.0]). Mean baseline 24-h systolic blood pressure was 128 (10) mmHg and significantly reduced at ST (-6.1 mmHg [-9.1, -3.1]; P < 0.001) and ET (-7.2 mmHg [-10.0, -4.3]; P < 0.001). Dapagliflozin did not significantly alter plasma volume or intracellular volume, while extracellular volume changed at ST (-0.7 L [-1.3, -0.1]; P = 0.02). As expected, 24-h urinary glucose excretion significantly increased during dapagliflozin treatment and reversed during FU.

CONCLUSIONS

During standardized sodium intake, dapagliflozin reduced blood pressure without clear changes in urinary sodium excretion, suggesting that factors other than natriuresis and volume changes may contribute to the blood pressure-lowering effects.

A metabolomics-based molecular pathway analysis of how the sodium-glucose co-transporter-2 inhibitor dapagliflozin may slow kidney function decline in patients with diabetes

AIM

To investigate which metabolic pathways are targeted by the sodium-glucose co-transporter-2 inhibitor dapagliflozin to explore the molecular processes involved in its renal protective effects.

METHODS

An unbiased mass spectrometry plasma metabolomics assay was performed on baseline and follow-up (week 12) samples from the EFFECT II trial in patients with type 2 diabetes with non-alcoholic fatty liver disease receiving dapagliflozin 10 mg/day (n = 19) or placebo (n = 6). Transcriptomic signatures from tubular compartments were identified from kidney biopsies collected from patients with diabetic kidney disease (DKD) (n = 17) and healthy controls (n = 30) from the European Renal cDNA Biobank. Serum metabolites that significantly changed after 12 weeks of dapagliflozin were mapped to a metabolite-protein interaction network. These proteins were then linked with intra-renal transcripts that were associated with DKD or estimated glomerular filtration rate (eGFR). The impacted metabolites and their protein-coding transcripts were analysed for enriched pathways.

RESULTS

Of all measured (n = 812) metabolites, 108 changed (P < 0.05) during dapagliflozin treatment and 74 could be linked to 367 unique proteins/genes. Intra-renal mRNA expression analysis of the genes encoding the metabolite-associated proteins using kidney biopsies resulted in 105 genes that were significantly associated with eGFR in patients with DKD, and 135 genes that were differentially expressed between patients with DKD and controls. The combination of metabolites and transcripts identified four enriched pathways that were affected by dapagliflozin and associated with eGFR: glycine degradation (mitochondrial function), TCA cycle II (energy metabolism), L-carnitine biosynthesis (energy metabolism) and superpathway of citrulline metabolism (nitric oxide synthase and endothelial function).

CONCLUSION

The observed molecular pathways targeted by dapagliflozin and associated with DKD suggest that modifying molecular processes related to energy metabolism, mitochondrial function and endothelial function may contribute to its renal protective effect.

The Novel Adipokine Gremlin 1 Antagonizes Insulin Action and Is Increased in Type 2 Diabetes and NAFLD/NASH

The BMP2/4 antagonist and novel adipokine Gremlin 1 is highly expressed in human adipose cells and increased in hypertrophic obesity. As a secreted antagonist, it inhibits the effect of BMP2/4 on adipose precursor cell commitment/differentiation. We examined mRNA levels of Gremlin 1 in key target tissues for insulin and also measured tissue and serum levels in several carefully phenotyped human cohorts. Gremlin 1 expression was high in adipose tissue, higher in visceral than in subcutaneous tissue, increased in obesity, and further increased in type 2 diabetes (T2D). A similar high expression was seen in liver biopsies, but expression was considerably lower in skeletal muscles. Serum levels were increased in obesity but most prominently in T2D. Transcriptional activation in both adipose tissue and liver as well as serum levels were strongly associated with markers of insulin resistance in vivo (euglycemic clamps and HOMA of insulin resistance), and the presence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). We also found Gremlin 1 to antagonize insulin signaling and action in human primary adipocytes, skeletal muscle, and liver cells. Thus, Gremlin 1 is a novel secreted insulin antagonist and biomarker as well as a potential therapeutic target in obesity and its complications T2D and NAFLD/NASH.

Characterization of Human Induced Pluripotent Stem Cell-Derived Hepatocytes with Mature Features and Potential for Modeling Metabolic Diseases

There is a strong anticipated future for human induced pluripotent stem cell-derived hepatocytes (hiPS-HEP), but so far, their use has been limited due to insufficient functionality. We investigated the potential of hiPS-HEP as an in vitro model for metabolic diseases by combining transcriptomics with multiple functional assays. The transcriptomics analysis revealed that 86% of the genes were expressed at similar levels in hiPS-HEP as in human primary hepatocytes (hphep). Adult characteristics of the hiPS-HEP were confirmed by the presence of important hepatocyte features, e.g., Albumin secretion and expression of major drug metabolizing genes. Normal energy metabolism is crucial for modeling metabolic diseases, and both transcriptomics data and functional assays showed that hiPS-HEP were similar to hphep regarding uptake of glucose, low-density lipoproteins (LDL), and fatty acids. Importantly, the inflammatory state of the hiPS-HEP was low under standard conditions, but in response to lipid accumulation and ER stress the inflammation marker tumor necrosis factor α (TNFα) was upregulated. Furthermore, hiPS-HEP could be co-cultured with primary hepatic stellate cells both in 2D and in 3D spheroids, paving the way for using these co-cultures for modeling non-alcoholic steatohepatitis (NASH). Taken together, hiPS-HEP have the potential to serve as an in vitro model for metabolic diseases. Furthermore, differently expressed genes identified in this study can serve as targets for future improvements of the hiPS-HEP.

Impaired Adipogenesis and Dysfunctional Adipose Tissue in Human Hypertrophic Obesity

The subcutaneous adipose tissue (SAT) is the largest and best storage site for excess lipids. However, it has a limited ability to expand by recruiting and/or differentiating available precursor cells. When inadequate, this leads to a hypertrophic expansion of the cells with increased inflammation, insulin resistance, and a dysfunctional prolipolytic tissue. Epi-/genetic factors regulate SAT adipogenesis and genetic predisposition for type 2 diabetes is associated with markers of an impaired SAT adipogenesis and development of hypertrophic obesity also in nonobese individuals. We here review mechanisms for the adipose precursor cells to enter adipogenesis, emphasizing the role of bone morphogenetic protein-4 (BMP-4) and its endogenous antagonist gremlin-1, which is increased in hypertrophic SAT in humans. Gremlin-1 is a secreted and a likely important mechanism for the impaired SAT adipogenesis in hypertrophic obesity. Transiently increasing BMP-4 enhances adipogenic commitment of the precursor cells while maintained BMP-4 signaling during differentiation induces a beige/brown oxidative phenotype in both human and murine adipose cells. Adipose tissue growth and development also requires increased angiogenesis, and BMP-4, as a proangiogenic molecule, may also be an important feedback regulator of this. Hypertrophic obesity is also associated with increased lipolysis. Reduced lipid storage and increased release of FFA by hypertrophic SAT are important mechanisms for the accumulation of ectopic fat in the liver and other places promoting insulin resistance. Taken together, the limited expansion and storage capacity of SAT is a major driver of the obesity-associated metabolic complications.

BMP4 Gene Therapy in Mature Mice Reduces BAT Activation but Protects from Obesity by Browning Subcutaneous Adipose Tissue

We examined the effect of Bone Morphogenetic Protein 4 (BMP4) on energy expenditure in adult mature mice by targeting the liver with adeno-associated viral (AAV) BMP4 vectors to increase circulating levels. We verified the direct effect of BMP4 in inducing a brown oxidative phenotype in differentiating preadipocytes in vitro. AAV-BMP4-treated mice display marked browning of subcutaneous adipocytes, with increased mitochondria and Uncoupling Protein 1 (UCP1). These mice are protected from obesity on a high-fat diet and have increased whole-body energy expenditure, improved insulin sensitivity, reduced liver fat, and reduced adipose tissue inflammation. On a control diet, they show unchanged body weight but improved insulin sensitivity. In contrast, AAV-BMP4-treated mice showed beiging of BAT with reduced UCP1, increased lipids, and reduced hormone-sensitive lipase (HSL). Thus, BMP4 exerts different effects on WAT and BAT, but the overall effect is to enhance insulin sensitivity and whole-body energy expenditure by browning subcutaneous adipose tissue.

TP53INP2 regulates adiposity by activating β-catenin through autophagy-dependent sequestration of GSK3β

Excessive fat accumulation is a major risk factor for the development of type 2 diabetes mellitus and other common conditions, including cardiovascular disease and certain types of cancer. Here, we identify a mechanism that regulates adiposity based on the activator of autophagy TP53INP2. We report that TP53INP2 is a negative regulator of adipogenesis in human and mouse preadipocytes. In keeping with this, TP53INP2 ablation in mice caused enhanced adiposity, which was characterized by greater cellularity of subcutaneous adipose tissue and increased expression of master adipogenic genes. TP53INP2 modulates adipogenesis through autophagy-dependent sequestration of GSK3β into late endosomes. GSK3β sequestration was also dependent on ESCRT activity. As a result, TP53INP2 promotes greater β-catenin levels and induces the transcriptional activity of TCF/LEF transcription factors. These results demonstrate a link between autophagy, sequestration of GSK3β into late endosomes and inhibition of adipogenesis in vivo.

CCN5/WISP2 and metabolic diseases

Obesity and type 2 diabetes increase worldwide at an epidemic rate. It is expected that by the year 2030 around 500 million people will have diabetes; predominantly type 2 diabetes. The CCN family of proteins has become of interest in both metabolic and other common human diseases because of their effects on mesenchymal stem cell (MSCs) proliferation and differentiation as well as being important regulators of fibrosis. We here review current knowledge of the WNT1 inducible signaling pathway protein 2 (CCN5/WISP2). It has been shown to be an important regulator of both these processes through effects on both the canonical WNT and the TGFβ pathways. It is also under normal regulation by the adipogenic commitment factor BMP4, in contrast to conventional canonical WNT ligands, and allows MSCs to undergo normal adipose cell differentiation. CCN5/WISP2 is highly expressed in, and secreted by, MSCs and is an important regulator of MSCs growth. In a transgenic mouse model overexpressing CCN5/WISP2 in the adipose tissue, we have shown that it is secreted and circulating in the blood, the mice develop hypercellular white and brown adipose tissue, have increased lean body mass and enlarged hypercellular hearts. Obese transgenic mice had improved insulin sensitivity. Interestingly, the anti-fibrotic effect of CCN5/WISP2 is protective against heart failure by inhibition of the TGFβ pathway. Understanding how CCN5/WISP2 is regulated and signals is important and may be useful for developing new treatment strategies in obesity and metabolic diseases and it can also be a target in regenerative medicine.

Epigenetic modifications of the Zfp/ZNF423 gene control murine adipogenic commitment and are dysregulated in human hypertrophic obesity

AIMS/HYPOTHESIS

Subcutaneous adipocyte hypertrophy is associated with insulin resistance and increased risk of type 2 diabetes, and predicts its future development independent of obesity. In humans, subcutaneous adipose tissue hypertrophy is a consequence of impaired adipocyte precursor cell recruitment into the adipogenic pathway rather than a lack of precursor cells. The zinc finger transcription factor known as zinc finger protein (ZFP) 423 has been identified as a major determinant of pre-adipocyte commitment and maintained white adipose cell function. Although its levels do not change during adipogenesis, ectopic expression of Zfp423 in non-adipogenic murine cells is sufficient to activate expression of the gene encoding peroxisome proliferator-activated receptor γ (Pparγ; also known as Pparg) and increase the adipogenic potential of these cells. We investigated whether the Zfp423 gene is under epigenetic regulation and whether this plays a role in the restricted adipogenesis associated with hypertrophic obesity.

METHODS

Murine 3T3-L1 and NIH-3T3 cells were used as fibroblasts committed and uncommitted to the adipocyte lineage, respectively. Human pre-adipocytes were isolated from the stromal vascular fraction of subcutaneous adipose tissue of 20 lean non-diabetic individuals with a wide adipose cell size range. mRNA levels were measured by quantitative real-time PCR, while methylation levels were analysed by bisulphite sequencing. Chromatin structure was analysed by micrococcal nuclease protection assay, and DNA-methyltransferases were chemically inhibited by 5-azacytidine. Adipocyte differentiation rate was evaluated by Oil Red O staining.

RESULTS

Comparison of uncommitted (NIH-3T3) and committed (3T3-L1) adipose precursor cells revealed that Zfp423 expression increased (p < 0.01) in parallel with the ability of the cells to differentiate into mature adipocytes owing to both decreased promoter DNA methylation (p < 0.001) and nucleosome occupancy (nucleosome [NUC] 1 p < 0.01; NUC2 p < 0.001) in the 3T3-L1 compared with NIH-3T3 cells. Interestingly, non-adipogenic epigenetic profiles can be reverted in NIH-3T3 cells as 5-azacytidine treatment increased Zfp423 mRNA levels (p < 0.01), reduced DNA methylation at a specific CpG site (p < 0.01), decreased nucleosome occupancy (NUC1, NUC2: p < 0.001) and induced adipocyte differentiation (p < 0.05). These epigenetic modifications can also be initiated in response to changes in the pre-adipose cell microenvironment, in which bone morphogenetic protein 4 (BMP4) plays a key role. We finally showed that, in human adipocyte precursor cells, impaired epigenetic regulation of zinc nuclear factor (ZNF)423 (the human orthologue of murine Zfp423) was associated with inappropriate subcutaneous adipose cell hypertrophy. As in NIH-3T3 cells, the normal ZNF423 epigenetic profile was rescued by 5-azacytidine exposure.

CONCLUSIONS/INTERPRETATION

Our results show that epigenetic events regulate the ability of precursor cells to commit and differentiate into mature adipocytes by modulating ZNF423, and indicate that dysregulation of these mechanisms accompanies subcutaneous adipose tissue hypertrophy in humans.

Increased adipose tissue aromatase activity improves insulin sensitivity and reduces adipose tissue inflammation in male mice

Females are, in general, more insulin sensitive than males. To investigate whether this is a direct effect of sex-steroids (SS) in white adipose tissue (WAT), we developed a male mouse model overexpressing the aromatase enzyme, converting testosterone (T) to estradiol (E₂), specifically in WAT (Ap2-arom mice). Adipose tissue E₂ levels were increased while circulating SS levels were unaffected in male Ap2-arom mice. Importantly, male Ap2-arom mice were more insulin sensitive compared with WT mice and exhibited increased serum adiponectin levels and upregulated expression of Glut4 and Irs1 in WAT. The expression of markers of macrophages and immune cell infiltration was markedly decreased in WAT of male Ap2-arom mice. The adipogenesis was enhanced in male Ap2-arom mice, supported by elevated Pparg expression in WAT and enhanced differentiation of preadipocyte into mature adipocytes. In summary, increased adipose tissue aromatase activity reduces adipose tissue inflammation and improves insulin sensitivity in male mice. We propose that estrogen increases insulin sensitivity via a local effect in WAT on adiponectin expression, adipose tissue inflammation, and adipogenesis.

Metabolic characteristics of individuals at a high risk of type 2 diabetes - a comparative cross-sectional study

BACKGROUND

Type 2 diabetes (T2D) is associated with substantial morbidity and mortality. Individuals with a family history of T2D are at an increased risk of developing the disease. The aim of this study was to assess metabolic differences between first-degree relatives (FDR) of T2D patients and persons with no known family history of T2D (non-FDR).

METHODS

In 200 FDR and 73 non-FDR, we compared anthropometrics, glucose tolerance status, different measurements of insulin secretion, insulin resistance, as well as blood lipids and other blood analyses.

RESULTS

In the FDR group, 30 individuals had impaired glucose tolerance or T2D. Among the non-FDR, two individuals had impaired glucose tolerance. In unadjusted data, the FDR were older, had stronger heredity for coronary heart disease, lower body mass index and weight, higher OGTT plasma glucose concentrations, and impaired insulin secretion (all p < 0.05). Using propensity score, we matched the groups, resulting in significantly stronger heredity of coronary heart disease, higher OGTT plasma glucose at 60 and 90 min, larger glucose area under curve during the OGTT and higher serum creatinine among the FDR. Using least squares means, OGTT glucose at 60 and 120 min, as well as the area under curve, and OGTT insulin levels at 60 min were significantly higher. Body mass index was negatively correlated with insulin sensitivity (MI) and positively correlated with HOMA-β, a measurement of insulin secretion.

CONCLUSIONS

We show that FDR are more likely to have impaired glucose tolerance and display higher OGTT plasma glucose and insulin, indicating an unfavorable metabolic profile. We conclude that OGTT is a simple and yet informative metabolic assessment in the FDR group. In both groups, we saw a negative correlation between body mass index and MI, confirming the role of body mass index in insulin resistance.

Cephalic phase of insulin secretion in response to a meal is unrelated to family history of type 2 diabetes

The pre-absorptive cephalic phase of insulin secretion is elicited during the first ten min of a meal and before glucose levels rise. Its importance for insulin release during the post-absorptive phase has been well documented in animals but its presence or importance in man has become increasingly controversial. We here examined the presence of an early cephalic phase of insulin release in 31 well matched individuals without (n = 15) or with (n = 16) a known family history of type 2 diabetes (first-degree relatives; FDR). We also examined the potential differences in individuals with or without impaired fasting (IFG) and impaired glucose tolerance (IGT). We here demonstrate that a cephalic phase of insulin secretion was present in all individuals examined and without any differences between control persons and FDR or IFG/IGT. However, the overall importance of the cephalic phase is conjectural since it was unrelated to the subsequent post-absorptive insulin release or glucose tolerance. One of the best predictors of the incremental cephalic phase of insulin release was fasting insulin level and, thus, a relation to degree of insulin sensitivity is likely. In conclusion, an early pre-absorptive and cephalic phase of insulin release is robustly present in man. However, we could not document any relation to family history of Type 2 diabetes nor to the post-absorptive phase and, thus, confirm its importance for subsequent degree of insulin release or glucose tolerance.

Metabolic predictors of impaired glucose tolerance and type 2 diabetes in a predisposed population--A prospective cohort study

BACKGROUND

We characterized in detail (oral and intravenous glucose tolerance tests (OGTT and IVGTT), euglycemic hyperinsulinemic clamp, adipose tissue biopsy), healthy first-degree relatives (FDR) of individuals with type 2 diabetes (T2D), to examine predictive factors for future development of impaired glucose tolerance (IGT) or T2D.

METHODS

Non-diabetic FDR (n = 138, mean age 40.5 ± 6.5 years, 57 % women) underwent an extended OGTT every 3 years to assess any deterioration in glucose tolerance status. Differences between groups were assessed by logistic fit for continuous variables and by contingency analysis for categorical variables. Multiple logistic regression analysis was applied to adjust for confounding variables.

RESULTS

At follow-up (mean 5.6 ± 2.4 years) 19 subjects had IGT and 4 had T2D. At baseline these 23 subjects had more family members with T2D, higher fasting plasma glucose, higher OGTT plasma glucose at 120 min, higher HbA1c, lower M-value and higher total cholesterol compared to subjects with normal glucose tolerance (NGT). There were significantly larger changes in weight, BMI, fasting plasma glucose, OGTT plasma glucose at 120 min and HbA1c in individuals developing IGT or T2D during the follow-up period than the subjects remaining NGT. Crude predictors of deteriorating glucose tolerance were age, family history of diabetes and of hypertension, OGTT plasma glucose levels at 60 min, 90 min, and 120 min, as well as serum bilirubin, ALP and creatinine (p-values <0.05). A multiple nominal logistic regression model revealed that male sex, low M-value and high physical exercise (p-values <0.05) predicted development of IGT/T2DM.

CONCLUSION

In sum, genetically predisposed individuals for T2D with deteriorating glucose tolerance exhibit insulin resistance as well as beta-cell and signs of adipose tissue dysfunction, emphasizing the multifactorial pathophysiology in the development of IGT and T2D.

BMP4 and BMP Antagonists Regulate Human White and Beige Adipogenesis

The limited expandability of subcutaneous adipose tissue, due to reduced ability to recruit and differentiate new adipocytes, prevents its buffering effect in obesity and is characterized by expanded adipocytes (hypertrophic obesity). Bone morphogenetic protein-4 (BMP4) plays a key role in regulating adipogenic precursor cell commitment and differentiation. We found BMP4 to be induced and secreted by differentiated (pre)adipocytes, and BMP4 was increased in large adipose cells. However, the precursor cells exhibited a resistance to BMP4 owing to increased secretion of the BMP inhibitor Gremlin-1 (GREM1). GREM1 is secreted by (pre)adipocytes and is an inhibitor of both BMP4 and BMP7. BMP4 alone, and/or silencing GREM1, increased transcriptional activation of peroxisome proliferator-activated receptor γ and promoted the preadipocytes to assume an oxidative beige/brown adipose phenotype including markers of increased mitochondria and PGC1α. Driving white adipose differentiation inhibited the beige/brown markers, suggesting the presence of multipotent adipogenic precursor cells. However, silencing GREM1 and/or adding BMP4 during white adipogenic differentiation reactivated beige/brown markers, suggesting that increased BMP4 preferentially regulates the beige/brown phenotype. Thus, BMP4, secreted by white adipose cells, is an integral feedback regulator of both white and beige adipogenic commitment and differentiation, and resistance to BMP4 by GREM1 characterizes hypertrophic obesity.

Insulin resistance and impaired adipogenesis

The adipose tissue is crucial in regulating insulin sensitivity and risk for diabetes through its lipid storage capacity and thermogenic and endocrine functions. Subcutaneous adipose tissue (SAT) stores excess lipids through expansion of adipocytes (hypertrophic obesity) and/or recruitment of new precursor cells (hyperplastic obesity). Hypertrophic obesity in humans, a characteristic of genetic predisposition for diabetes, is associated with abdominal obesity, ectopic fat accumulation, and the metabolic syndrome (MS), while the ability to recruit new adipocytes prevents this. We review the regulation of adipogenesis, its relation to SAT expandability and the risks of ectopic fat accumulation, and insulin resistance. The actions of GLUT4 in SAT, including a novel family of lipids enhancing insulin sensitivity/secretion, and the function of bone morphogenetic proteins (BMPs) in white and beige/brown adipogenesis in humans are highlighted.

Discovery of a class of endogenous mammalian lipids with anti-diabetic and anti-inflammatory effects

Increased adipose tissue lipogenesis is associated with enhanced insulin sensitivity. Mice overexpressing the Glut4 glucose transporter in adipocytes have elevated lipogenesis and increased glucose tolerance despite being obese with elevated circulating fatty acids. Lipidomic analysis of adipose tissue revealed the existence of branched fatty acid esters of hydroxy fatty acids (FAHFAs) that were elevated 16- to 18-fold in these mice. FAHFA isomers differ by the branched ester position on the hydroxy fatty acid (e.g., palmitic-acid-9-hydroxy-stearic-acid, 9-PAHSA). PAHSAs are synthesized in vivo and regulated by fasting and high-fat feeding. PAHSA levels correlate highly with insulin sensitivity and are reduced in adipose tissue and serum of insulin-resistant humans. PAHSA administration in mice lowers ambient glycemia and improves glucose tolerance while stimulating GLP-1 and insulin secretion. PAHSAs also reduce adipose tissue inflammation. In adipocytes, PAHSAs signal through GPR120 to enhance insulin-stimulated glucose uptake. Thus, FAHFAs are endogenous lipids with the potential to treat type 2 diabetes.

The Novel Secreted Adipokine WNT1-inducible Signaling Pathway Protein 2 (WISP2) Is a Mesenchymal Cell Activator of Canonical WNT

WNT1-inducible-signaling pathway protein 2 (WISP2) is primarily expressed in mesenchymal stem cells, fibroblasts, and adipogenic precursor cells. It is both a secreted and cytosolic protein, the latter regulating precursor cell adipogenic commitment and PPARγ induction by BMP4. To examine the effect of the secreted protein, we expressed a full-length and a truncated, non-secreted WISP2 in NIH3T3 fibroblasts. Secreted, but not truncated WISP2 activated the canonical WNT pathway with increased β-catenin levels, its nuclear targeting phosphorylation, and LRP5/6 phosphorylation. It also inhibited Pparg activation and the effect of secreted WISP2 was reversed by the WNT antagonist DICKKOPF-1. Differentiated 3T3-L1 adipose cells were also target cells where extracellular WISP2 activated the canonical WNT pathway, inhibited Pparg and associated adipose genes and, similar to WNT3a, promoted partial dedifferentiation of the cells and the induction of a myofibroblast phenotype with activation of markers of fibrosis. Thus, WISP2 exerts dual actions in mesenchymal precursor cells; secreted WISP2 activates canonical WNT and maintains the cells in an undifferentiated state, whereas cytosolic WISP2 regulates adipogenic commitment.

Adipocyte-released insulin-like growth factor-1 is regulated by glucose and fatty acids and controls breast cancer cell growth in vitro

AIMS/HYPOTHESIS

Type 2 diabetes and obesity are associated with increased risk of site-specific cancers. We have investigated whether metabolic alterations at the level of adipose-derived differentiating cells may affect specific phenotypes of breast cancer cells.

METHODS

Growth profiles of breast cancer cell lines were evaluated in co-cultures with differentiated adipocytes or their precursor cells and upon treatment with adipocyte conditioned media. Production and release of cytokines and growth factors were assessed by real-time RT-PCR and multiplex-based ELISA assays.

RESULTS

Co-cultures with either differentiated mouse 3T3-L1 or human mammary adipocytes increased viability of MCF-7 cells to a greater extent, when compared with their undifferentiated precursors. Adipocytes cultured in 25 mmol/l glucose were twofold more effective in promoting cell growth, compared with those grown in 5.5 mmol/l glucose, and activated mitogenic pathways in MCF-7 cells. Growth-promoting action was also enhanced when adipocytes were incubated in the presence of palmitate or oleate. Interestingly, 3T3-L1 and human adipocytes released higher amounts of keratinocyte-derived chemokine/IL-8, the protein 'regulated upon activation, normally T expressed, and secreted' (RANTES), and IGF-1, compared with their precursor cells. Their levels were reduced upon incubation with low glucose and enhanced by fatty acids. Moreover, both undifferentiated cells and differentiated adipocytes from obese individuals displayed about twofold higher IGF-1 release and MCF-7 cell growth induction than lean individuals. Finally, inhibition of the IGF-1 pathway almost completely prevented the growth-promoting effect of adipocytes on breast cancer cells.

CONCLUSIONS/INTERPRETATION

IGF-1 release by adipocytes is regulated by glucose and fatty acids and may contribute to the control of cancer cell growth in obese individuals.

Adipose tissue dysregulation and reduced insulin sensitivity in non-obese individuals with enlarged abdominal adipose cells

BACKGROUND

Obesity contributes to Type 2 diabetes by promoting systemic insulin resistance. Obesity causes features of metabolic dysfunction in the adipose tissue that may contribute to later impairments of insulin action in skeletal muscle and liver; these include reduced insulin-stimulated glucose transport, reduced expression of GLUT4, altered expression of adipokines, and adipocyte hypertrophy. Animal studies have shown that expansion of adipose tissue alone is not sufficient to cause systemic insulin resistance in the absence of adipose tissue metabolic dysfunction. To determine if this holds true for humans, we studied the relationship between insulin resistance and markers of adipose tissue dysfunction in non-obese individuals.

METHOD

32 non-obese first-degree relatives of Type 2 diabetic patients were recruited. Glucose tolerance was determined by an oral glucose tolerance test and insulin sensitivity was measured with the hyperinsulinaemic-euglycaemic clamp. Blood samples were collected and subcutaneous abdominal adipose tissue biopsies obtained for gene/protein expression and adipocyte cell size measurements.

RESULTS

Our findings show that also in non-obese individuals low insulin sensitivity is associated with signs of adipose tissue metabolic dysfunction characterized by low expression of GLUT4, altered adipokine profile and enlarged adipocyte cell size. In this group, insulin sensitivity is positively correlated to GLUT4 mRNA (R = 0.49, p = 0.011) and protein (R = 0.51, p = 0.004) expression, as well as with circulating adiponectin levels (R = 0.46, 0 = 0.009). In addition, insulin sensitivity is inversely correlated to circulating RBP4 (R = -0.61, 0 = 0.003) and adipocyte cell size (R = -0.40, p = 0.022). Furthermore, these features are inter-correlated and also associated with other clinical features of the metabolic syndrome in the absence of obesity. No association could be found between the hypertrophy-associated adipocyte dysregulation and HIF-1alpha in this group of non-obese individuals.

CONCLUSIONS

In conclusion, these findings support the concept that it is not obesity per se, but rather metabolic dysfunction of adipose tissue that is associated with systemic insulin resistance and the metabolic syndrome.

Glucose tolerance, insulin sensitivity and insulin release in European non-diabetic carriers of a polymorphism upstream of CDKN2A and CDKN2B

AIMS/HYPOTHESIS

The aim of this study was to investigate the association of the rs10811661 polymorphism near the CDKN2B/CDKN2A genes with glucose tolerance, insulin sensitivity and insulin release in three samples of white people with European ancestry.

METHODS

Sample 1 comprised 845 non-diabetic offspring of type 2 diabetes patients recruited in five European centres participating in the EUGENE2 study. Samples 2 and 3 comprised, respectively, 864 and 524 Italian non-diabetic participants. All individuals underwent an OGTT. Screening for the rs10811661 polymorphism was performed using a TaqMan allelic discrimination assay.

RESULTS

The rs10811661 polymorphism did not show a significant association with age, BMI and insulin sensitivity. Participants carrying the TT genotype showed a significant reduction in insulin release, measured by an OGTT-derived index, compared with carriers of the C allele, in the three samples. When these results were pooled with those of three published studies, and meta-analysed with a random-effects model, the T allele was significantly associated with reduced insulin secretion (-35.09 [95% CI 14.68-55.52], p = 0.0008 for CC+CT vs TT; and -29.45 [95% CI 9.51-49.38], p = 0.0038, for the additive model). In addition, in our three samples, participants carrying the TT genotype exhibited an increased risk for impaired glucose tolerance (IGT) compared with carriers of the C allele (OR 1.55 [95% CI 1.20-1.95] for the meta-analysis of the three samples).

CONCLUSIONS/INTERPRETATION

Our data, together with the meta-analysis of previously published studies, show that the rs10811661 polymorphism is associated with impaired insulin release and IGT, suggesting that this variant may contribute to type 2 diabetes by affecting beta cell function.

Circulating fibroblast growth factor-23 is associated with fat mass and dyslipidemia in two independent cohorts of elderly individuals

OBJECTIVE

Disturbances in mineral metabolism define an increased cardiovascular risk in patients with chronic kidney disease. Fibroblast growth factor-23 (FGF23) is a circulating regulator of phosphate and vitamin D metabolism and has recently been implicated as a putative pathogenic factor in cardiovascular disease. Because other members of the FGF family play a role in lipid and glucose metabolism, we hypothesized that FGF23 would associate with metabolic factors that predispose to an increased cardiovascular risk. The goal of this study was to investigate the relationship between FGF23 and metabolic cardiovascular risk factors in the community.

METHODS AND RESULTS

Relationships between serum FGF23 and body mass index (BMI), waist circumference, waist-to-hip ratio, serum lipids, and fat mass were examined in 2 community-based, cross-sectional cohorts of elderly whites (Osteoporotic Fractures in Men Study: 964 men aged 75±3.2; Prospective Investigation of the Vasculature in Uppsala Seniors study: 946 men and women aged 70). In both cohorts, FGF23 associated negatively with high-density lipoprotein and apolipoprotein A1 (7% to 21% decrease per 1-SD increase in log FGF23; P<0.01) and positively with triglycerides (11% to 14% per 1-SD increase in log FGF23; P<0.01). A 1-SD increase in log FGF23 was associated with a 7% to 20% increase in BMI, waist circumference, and waist-to-hip ratio and a 7% to 18% increase in trunk and total body fat mass (P<0.01) as determined by whole-body dual x-ray absorptiometry. FGF23 levels were higher in subjects with the metabolic syndrome compared with those without (46.4 versus 41.2 pg/mL; P<0.05) and associated with an increased risk of having the metabolic syndrome (OR per 1-SD increase in log FGF23, 1.21; 95% CI, 1.04 to 1.40; P<0.05).

CONCLUSIONS

We report for the first time on associations between circulating FGF23, fat mass, and adverse lipid metabolism resembling the metabolic syndrome, potentially representing a novel pathway(s) linking high FGF23 to an increased cardiovascular risk.

Antagonistic effects of thiazolidinediones and cytokines in lipotoxicity

Ectopic lipid accumulation is promoted by obesity and an impaired ability to accumulate triglycerides in the subcutaneous depots. The adipose tissue is dysregulated in hypertrophic obesity, i.e., when the adipose cells have become enlarged. In some individuals, however, obesity is a consequence of a recruitment of new adipocytes, i.e., a hyperplastic obesity. This form of obesity is usually not associated with the metabolic complications and is termed "obese but metabolically normal". We here review recent findings showing that hypertrophic obesity is associated with an impaired differentiation of committed preadipocytes. This may be a primary (genetic?) event, thus leading to hypertrophic fat cells and the associated inflammation. However, it is also possible that the inflammation is a primary event allowing, in particular, TNFalpha to inhibit preadipocyte differentiation. TNFalpha, instead, promotes a partial transdifferentiation of the preadipocytes to assume a macrophage-like phenotype. PPARgamma activation promotes adipogenesis but can apparently not overcome the impaired preadipocyte differentiation seen in hypertrophic obesity.

Inflammation and impaired adipogenesis in hypertrophic obesity in man

Obesity is associated mainly with adipose cell enlargement in adult man (hypertrophic obesity), whereas the formation of new fat cells (hyperplastic obesity) predominates in the prepubertal age. Adipose cell size, independent of body mass index, is negatively correlated with whole body insulin sensitivity. Here, we review recent findings linking hypertrophic obesity with inflammation and a dysregulated adipose tissue, including local cellular insulin resistance with reduced IRS-1 and GLUT4 protein content. In addition, the number of preadipocytes in the abdominal subcutaneous adipose tissue capable of undergoing differentiation to adipose cells is reduced in hypertrophic obesity. This is likely to promote ectopic lipid accumulation, a well-known finding in these individuals and one that promotes insulin resistance and cardiometabolic risk. We also review recent results showing that TNFα, but not MCP-1, resistin, or IL-6, completely prevents normal adipogenesis in preadipocytes, activates Wnt signaling, and induces a macrophage-like phenotype in the preadipocytes. In fact, activated preadipocytes, rather than macrophages, may completely account for the increased release of chemokines and cytokines by the adipose tissue in obesity. Understanding the molecular mechanisms for the impaired preadipocyte differentiation in the subcutaneous adipose tissue in hypertrophic obesity is a priority since it may lead to new ways of treating obesity and its associated metabolic complications.

Acute hyperinsulinemia differentially regulates interstitial and circulating adiponectin oligomeric pattern in lean and insulin-resistant, obese individuals

CONTEXT

Hyperinsulinemia emerges as a negative modulator of the circulating high-molecular-weight adiponectin multimers.

OBJECTIVES

Here we asked whether, in vivo, acute hyperinsulinemia regulates adiponectin formation and oligomeric complex distribution at the transcriptional or posttranslational level.

DESIGN

Nine lean and nine uncomplicated obese males were studied in the postabsorptive state and during a euglycemic-hyperinsulinemic clamp combined with the microdialysis technique. Subcutaneous abdominal adipose tissue biopsies and interstitial and serum samples were taken at baseline and after the hyperinsulinemia. Adiponectin complexes were characterized by nonheating/nonreducing SDS-PAGE.

RESULTS

At baseline, serum and interstitial total adiponectin levels were lower (P < 0.01) in obese than in lean subjects primarily due to a reduction of the high-molecular-weight isoforms. After hyperinsulinemia, serum and interstitial total adiponectin was reduced in both groups. The degree of adiponectin reduction was more prominent in interstitial fluid than in serum. Lean individuals showed an equal suppression of the high-, low-, and middle-molecular-weight adiponectin complexes both in serum and in situ (P < 0.01 vs. basal). In obese subjects, despite the lower interstitial adiponectin subfractions, insulin challenge reduced significantly the circulating middle-molecular-weight forms only. At the mRNA level, adiponectin and its receptors 1 and 2, as well as the abundance of the endoplasmic reticulum chaperone proteins ERp44 and Epsilonro1-Lalpha were similar within the groups, before and after the clamp.

CONCLUSIONS

In human obesity, the impaired adiponectin oligomeric pattern in the circulation is mimicked at the tissue level, and hyperinsulinemia may differentially affect the compartmental distribution of the adiponectin complexes.

Impaired preadipocyte differentiation in human abdominal obesity: role of Wnt, tumor necrosis factor-alpha, and inflammation

OBJECTIVE

We examined preadipocyte differentiation in obese and nonobese individuals and the effect of cytokines and wingless-type MMTV (mouse mammary tumor virus) integration site family, member 3A (Wnt3a) protein on preadipocyte differentiation and phenotype.

RESEARCH DESIGN AND METHODS

Abdominal subcutaneous adipose tissue biopsies were obtained from a total of 51 donors with varying BMI. After isolation of the adipose and stromalvascular cells, inflammatory cells (CD14- and CD45-positive cells) were removed by immune magnetic separation. CD133-positive cells, containing early progenitor cells, were also isolated and quantified. The CD14- and CD45-negative preadipocytes were cultured with tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, resistin, or Wnt3a with or without a differentiation cocktail.

RESULTS

The number of preadipocytes able to differentiate to adipose cells was negatively correlated with both BMI and adipocyte cell size of the donors, whereas the number of CD133-positive cells was positively correlated with BMI, suggesting an impaired differentiation of preadipocytes in obesity. Cultured preadipocytes, like freshly isolated mature adipocytes, from obese individuals had an increased expression of mitogen-activated protein 4 kinase 4 (MAP4K4), which is known to inhibit peroxisome proliferator-activated receptor-gamma induction. TNF-alpha, but not IL-6 or resistin, increased Wnt10b, completely inhibited the normal differentiation of the preadipocytes, and instead induced a proinflammatory and macrophage-like phenotype of the cells.

CONCLUSIONS

The apparent number of preadipocytes in the abdominal subcutaneous tissue that can undergo differentiation is reduced in obesity with enlarged fat cells, possibly because of increased MAP4K4 levels. TNF-alpha promoted a macrophage-like phenotype of the preadipocytes, including several macrophage markers. These results document the plasticity of human preadipocytes and the inverse relationship between lipid storage and proinflammatory capacity.

Inflamed adipose tissue, insulin resistance and vascular injury

Type 2 diabetes is the most common metabolic disorder today and has reached epidemic proportions in many countries. Insulin resistance and inflammation play a central role in the pathogenesis of type 2 diabetes and are present long before the onset of the disease. During this time, many of the complications associated with type 2 diabetes are initiated. Of major concern is the two- to fourfold increase in cardiovascular morbidity and mortality in this group compared to a nondiabetic population. Obesity, characterized by enlarged fat cells, and insulin resistance are, like type 2 diabetes, associated with impaired adipogenesis and a low-grade chronic inflammation that to a large extent emanates from the adipose tissue. Both these processes contribute to unfavourable alterations of the circulating levels of several bioactive molecules (adipokines) that are secreted from the adipose tissue, many of which have documented inhibitory effects on insulin sensitivity in the liver and peripheral tissues and, in addition, have negative effects on the cardiovascular system.Here we review current knowledge of the adipose tissue as an endocrine organ, the local and systemic effects of a chronic state of low-grade inflammation residing in the adipose tissue, and, in particular, the effects of inflammation and circulating adipokines on the vascular wall.

Single-nucleotide polymorphism rs7754840 of CDKAL1 is associated with impaired insulin secretion in nondiabetic offspring of type 2 diabetic subjects and in a large sample of men with normal glucose tolerance

CONTEXT

CDKAL1 is a recently discovered susceptibility gene for type 2 diabetes.

OBJECTIVE

Our objective was to investigate the impact of rs7754840 of CDKAL1 on insulin secretion, insulin sensitivity, and risk of type 2 diabetes.

DESIGN AND SETTINGS

Study 1 (the EUGENE2 study) was a cross-sectional study including subjects from five white populations in Europe (Denmark, Finland, Germany, Italy, and Sweden). Study 2 is an ongoing prospective study of Finnish men.

PARTICIPANTS

In study 1, 846 nondiabetic offspring of type 2 diabetic patients (age 40 +/- 10 yr; body mass index 26.7 +/- 5.0 kg/m(2)) participated. In study 2, subjects included 3900 middle-aged men (533 type 2 diabetic and 3367 nondiabetic subjects).

INTERVENTIONS

INTERVENTIONS included iv glucose-tolerance test (IVGTT), oral glucose-tolerance test (OGTT), and euglycemic-hyperinsulinemic clamp in study 1 and OGTT in study 2.

MAIN OUTCOME MEASURES

Parameters of insulin secretion, insulin resistance, and glucose tolerance status were assessed.

RESULTS

In study 1, carriers of the GC and CC genotypes of rs7754840 had 11 and 24% lower first-phase insulin release in an IVGTT compared with that in carriers of the GG genotype (P = 0.002). The C allele was also associated with higher glucose area under the curve in an OGTT (P = 0.016). In study 2, rs7754840 was significantly associated with type 2 diabetes (P = 0.022) and markers of impaired insulin release [insulinogenic index (IGI), P = 0.012] in 2405 men with normal glucose tolerance.

CONCLUSIONS

rs7754840 of CDKAL1 was associated with markers of impaired insulin secretion in two independent studies. Furthermore, rs7754840 was associated with type 2 diabetes in Finnish men (study 2). Therefore, CDKAL1 is likely to increase the risk of type 2 diabetes by impairing insulin secretion.

The common SLC30A8 Arg325Trp variant is associated with reduced first-phase insulin release in 846 non-diabetic offspring of type 2 diabetes patients--the EUGENE2 study

AIMS/HYPOTHESIS

A recent genome-wide association study identified the SLC30A8 rs13266634 polymorphism encoding an Arg325Trp polymorphism in the zinc transporter protein member 8 (ZnT-8) to be associated with type 2 diabetes. Here, we investigate whether the polymorphism is related to altered insulin release in response to intravenous and oral glucose loads in non-diabetic offspring of type 2 diabetic patients.

METHODS

We genotyped SLC30A8 rs13266634 in 846 non-diabetic offspring of type 2 diabetic patients from five different white populations: Danish (n = 271), Finnish (n = 217), German (n = 149), Italian (n = 109) and Swedish (n = 100). Participants were subjected to both IVGTTs and OGTTs, and measurements of insulin sensitivity.

RESULTS

Homozygous carriers of the major type 2 diabetes C risk-allele showed a 19% decrease in first-phase insulin release (0-10 min) measured during the IVGTT (CC 3,624 +/- 3,197; CT 3,763 +/- 2,674; TT 4,478 +/- 3,032 pmol l(-1) min(-1), mean +/- SD; p = 0.007). We found no significant genotype effect on insulin release measured during the OGTT or on estimates of insulin sensitivity.

CONCLUSIONS/INTERPRETATION

Of European non-diabetic offspring of type 2 diabetes patients, 46% are homozygous carriers of the Arg325Trp polymorphism in ZnT-8, which is known to associate with type 2 diabetes. These diabetes-prone offspring are characterised by a 19% decrease in first-phase insulin release following an intravenous glucose load, suggesting a role for this variant in the pathogenesis of pancreatic beta cell dysfunction.

High circulating levels of RBP4 and mRNA levels of aP2, PGC-1alpha and UCP-2 predict improvement in insulin sensitivity following pioglitazone treatment of drug-naïve type 2 diabetic subjects

CONTEXT

High levels of circulating retinol-binding protein 4 (RBP4) and baseline expression of adipogenic genes correlate with subsequent improvement in insulin sensitivity following Thiazolidinedione (TZD) treatment.

OBJECTIVE

The aim was to identify baseline characteristics and early changes related to TZD treatment that could predict a good treatment response.

DESIGN

Subjects were examined with oral glucose tolerance test, intravenous glucose tolerance test, hyperinsulinaemic euglycaemic clamp, body composition and standard blood sampling at baseline and after 4 and 12 weeks treatment. Subcutaneous adipose tissue biopsies were taken from the abdominal region at baseline, after 3 days and 4 weeks treatment to examine the gene expression profile.

SETTING

Research laboratory in a University hospital.

PARTICIPANTS

Ten newly diagnosed and previously untreated type 2 diabetic subjects were treated with pioglitazone for 3 months.

MAIN OUTCOME MEASURES

Baseline characteristics and early changes related to TZD treatment that could predict the response after 3 months.

RESULTS

Pioglitazone improved insulin sensitivity after 4 weeks combined with lower glucose and insulin levels without any change in BMI. It was accompanied by lower circulating resistin and plasminogen activator inhibitor-1 levels rapidly increased levels of circulating total and high molecular weight adiponectin as well as adiponectin and adipocyte fatty acid-binding protein (aP2) mRNA expression in the adipose tissue. High levels of circulating RBP4 at baseline and adipose tissue expression of aP2, proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1alpha) and uncoupling protein 2 (UCP-2) predicted a good treatment response measured as improvement in insulin-stimulated whole-body glucose uptake after 3 months.

CONCLUSIONS

Circulating levels of RBP4 as an index of insulin sensitivity and mRNA levels of adipogenic genes correlate with the subsequent improvement in insulin sensitivity following TZD treatment.

A candidate type 2 diabetes polymorphism near the HHEX locus affects acute glucose-stimulated insulin release in European populations: results from the EUGENE2 study

OBJECTIVE

In recent genome-wide association studies, two single nucleotide polymorphisms (SNPs) near the HHEX locus were shown to be more frequent in type 2 diabetic patients than in control subjects. Based on HHEX's function during embryonic development of the ventral pancreas in mice, we investigated whether these SNPs affect beta-cell function in humans.

RESEARCH DESIGN AND METHODS

A total of 854 nondiabetic subjects, collected from five European clinical centers, were genotyped for the HHEX SNPs rs1111875 and rs7923837 and thoroughly characterized by an oral glucose tolerance test (OGTT). To assess glucose-stimulated insulin release, a subgroup of 758 subjects underwent an intravenous glucose tolerance test (IVGTT).

RESULTS

SNPs rs1111875 and rs7923837 were not associated with anthropometric data (age, weight, height, BMI, body fat, and waist and hip circumference). After adjustment for center, family relationship, sex, age, and BMI, both SNPs were also not associated with glucose and insulin concentrations in the fasting state and during the OGTT or with measures of insulin sensitivity. Furthermore, HHEX SNP rs1111875 was not associated with insulin release during the IVGTT. By contrast, the minor A-allele of HHEX SNP rs7923837 was significantly associated with higher IVGTT-derived first-phase insulin release before and after appropriate adjustment (P = 0.013 and P = 0.014, respectively).

CONCLUSIONS

A common genetic variation in the 3'-flanking region of the HHEX locus, i.e., SNP rs7923837, is associated with altered glucose-stimulated insulin release. This SNP's major allele represents a risk allele for beta-cell dysfunction and, thus, might confer increased susceptibility of beta-cells toward adverse environmental factors.

Inflamed adipose tissue: a culprit underlying the metabolic syndrome and atherosclerosis

The metabolic syndrome is associated with a dysregulated adipose tissue; in part a consequence of adipose cell enlargement and the associated infiltration of macrophages. Adipose cell enlargement leads to a proinflammatory state in the cells with reduced secretion of adiponectin and with increased secretion of several cytokines and chemokines including interleukin (IL)-6, IL-8, and MCP-1. MCP-1 has been shown to play an important role for the associated recruitment of macrophages into the adipose tissue. The increased release of cytokines leads to an impaired differentiation of the preadipocytes with reduced lipid accumulation and induction of adiponectin, thus promoting ectopic lipid storage. In particular tumor necrosis factor (TNF) alpha, but also IL-6, has been shown to induce these effects in preadipocytes and this is associated with an increased Wnt signaling maintaining the cells in an undifferentiated and proinflammatory state. The proinflammatory state in the adipose tissue also leads to a local insulin resistance including an impaired inhibitory effect of insulin on FFA release. The insulin resistance further supports the proinflammatory state because insulin, by itself, is both antilipolytic and antiinflammatory by antagonizing cytokine-induced activation of STAT signaling.

Insulin differentially modulates the peripheral endocannabinoid system in human subcutaneous abdominal adipose tissue from lean and obese individuals

Human obesity has been associated with a dysregulation of the peripheral and adipose tissue (AT) endocannabinoid system (ES). The aim of this study was to elucidate the acute in vivo effects of insulin on gene expression of the cannabinoid type 1 (CB-1) and type 2 (CB-2) receptors, as well as of the fatty acid amide hydrolase (FAAH) in the sc abdominal adipose tissue (SCAAT). Nine lean (L) and 9 obese (OB), but otherwise healthy males were studied in the fasting state and during a euglycemic hyperinsulinemic clamp (40 mU/m2 * min(-1)). SCAAT biopsies were obtained at baseline and after 270 min of i.v. maintained hyperinsulinemia. The basal SCAAT gene expression pattern revealed an upregulation of the FAAH in the OB (p=0.03 vs L), whereas similar CB-1 and CB-2 mRNA levels were seen. Following hyperinsulinemia, the FAAH mRNA levels significantly increased approximately 2-fold in the L (p=0.01 vs baseline) but not in the OB. In contrast, insulin failed to significantly change both the adipose CB-1 and CB-2 gene expression. Finally, the FAAH gene expression positively correlated with the fasting serum insulin concentration (r 0.66; p=0.01), whereas an inverse association with the whole-body glucose disposal (r -0.58; p<0.05) was seen. Taken together, these first time observations demonstrate that the ES-related genes in the SCAAT differentially respond to hyperinsulinemia in lean/insulin-sensitive and in obese/insulin-resistant individuals. We suggest that insulin may play a key role in the obesity-linked dysregulation of the adipose ES at the gene level.