Johannes A. Romijn

Inflammasome is a central player in the induction of obesity and insulin resistance

Inflammation plays a key role in the pathogenesis of obesity. Chronic overfeeding leads to macrophage infiltration in the adipose tissue, resulting in proinflammatory cytokine production. Both microbial and endogenous danger signals trigger assembly of the intracellular innate immune sensor Nlrp3, resulting in caspase-1 activation and production of proinflammatory cytokines IL-1β and IL-18. Here, we showed that mice deficient in Nlrp3, apoptosis-associated speck-like protein, and caspase-1 were resistant to the development of high-fat diet-induced obesity, which correlated with protection from obesity-induced insulin resistance. Furthermore, hepatic triglyceride content, adipocyte size, and macrophage infiltration in adipose tissue were all reduced in mice deficient in inflammasome components. Monocyte chemoattractant protein (MCP)-1 is a key molecule that mediates macrophage infiltration. Indeed, defective inflammasome activation was associated with reduced MCP-1 production in adipose tissue. Furthermore, plasma leptin and resistin that affect energy use and insulin sensitivity were also changed by inflammasome-deficiency. Detailed metabolic and molecular phenotyping demonstrated that the inflammasome controls energy expenditure and adipogenic gene expression during chronic overfeeding. These findings reveal a critical function of the inflammasome in obesity and insulin resistance, and suggest inhibition of the inflammasome as a potential therapeutic strategy.

Selective parasympathetic innervation of subcutaneous and intra-abdominal fat — functional implications

The wealth of clinical epidemiological data on the association between intra-abdominal fat accumulation and morbidity sharply contrasts with the paucity of knowledge about the determinants of fat distribution, which cannot be explained merely in terms of humoral factors. If it comes to neuronal control, until now, adipose tissue was reported to be innervated by the sympathetic nervous system only, known for its catabolic effect. We hypothesized the presence of a parasympathetic input stimulating anabolic processes in adipose tissue. Intra-abdominal fat pads in rats were first sympathetically denervated and then injected with the retrograde transneuronal tracer pseudorabies virus (PRV). The resulting labeling of PRV in the vagal motor nuclei of the brain stem reveals that adipose tissue receives vagal input. Next, we assessed the physiological impact of these findings by combining a fat pad-specific vagotomy with a hyperinsulinemic euglycemic clamp and RT-PCR analysis. Insulin-mediated glucose and FFA uptake were reduced by 33% and 36%, respectively, whereas the activity of the catabolic enzyme hormone-sensitive lipase increased by 51%. Moreover, expression of resistin and leptin mRNA decreased, whereas adiponectin mRNA did not change. All these data indicate an anabolic role for the vagal input to adipose tissue. Finally, we demonstrate somatotopy within the central part of the autonomic nervous system, as intra-abdominal and subcutaneous fat pads appeared to be innervated by separate sympathetic and parasympathetic motor neurons. In conclusion, parasympathetic input to adipose tissue clearly modulates its insulin sensitivity and glucose and FFA metabolism in an anabolic way. The implications of these findings for the (patho)physiology of fat distribution are discussed.

Beneficial effects of sorafenib on tumor progression, but not on radioiodine uptake, in patients with differentiated thyroid carcinoma.

OBJECTIVE Treatment options for patients with radioactive iodine (RaI) refractory metastases of differentiated thyroid carcinoma (DTC) are limited. We studied the effects of the multitarget tyrosine kinase inhibitor sorafenib on the reinduction of RaI uptake and tumor progression. DESIGN Open, single center, single arm 26-week prospective phase II study with open-ended extension. METHODS We treated 31 patients with progressive metastatic or locally advanced RaI refractory DTC with sorafenib 400 mg b.i.d. The primary endpoint was reinduction of RaI uptake at 26 weeks. Additional endpoints were the radiological response and the influence of bone metastases. RESULTS At 26 weeks of sorafenib therapy, no reinduction of RaI uptake at metastatic sites was observed, but 19 patients (59%) had a clinical beneficial response, eight of whom had a partial response (25%) and 11 had stable disease (34%). Seven patients had progressive disease (22%). Sorafenib was significantly less effective in patients with bone metastases. The estimated median progression free survival was 58 weeks (95% confidence interval, CI, 47-68). In general, thyroglobulin (Tg) response (both unstimulated and TSH stimulated) reflected radiological responses. The median time of the nadir of Tg levels was 3 months. Responses were not influenced by histological subtype, mutational status or other variables. No unusual side effects were observed. CONCLUSIONS Sorafenib has a beneficial effect on tumor progression in patients with metastatic DTC, but was less effective in patients with bone metastases. Diagnostic whole body scintigraphy did not reveal an effect of sorafenib on the reinduction of RaI uptake.

Impact of oral vancomycin on gut microbiota, bile acid metabolism, and insulin sensitivity

BACKGROUND & AIMS Obesity has been associated with changes in the composition and function of the intestinal microbiota. Modulation of the microbiota by antibiotics also alters bile acid and glucose metabolism in mice. Hence, we hypothesized that short term administration of oral antibiotics in humans would affect fecal microbiota composition and subsequently bile acid and glucose metabolism. METHODS In this single blinded randomized controlled trial, 20 male obese subjects with metabolic syndrome were randomized to 7 days of amoxicillin 500 mg t.i.d. or 7 days of vancomycin 500 mg t.i.d. At baseline and after 1 week of therapy, fecal microbiota composition (Human Intestinal Tract Chip phylogenetic microarray), fecal and plasma bile acid concentrations as well as insulin sensitivity (hyperinsulinemic euglycemic clamp using [6,6-(2)H2]-glucose tracer) were measured. RESULTS Vancomycin reduced fecal microbial diversity with a decrease of gram-positive bacteria (mainly Firmicutes) and a compensatory increase in gram-negative bacteria (mainly Proteobacteria). Concomitantly, vancomycin decreased fecal secondary bile acids with a simultaneous postprandial increase in primary bile acids in plasma (p<0.05). Moreover, changes in fecal bile acid concentrations were predominantly associated with altered Firmicutes. Finally, administration of vancomycin decreased peripheral insulin sensitivity (p<0.05). Amoxicillin did not affect any of these parameters. CONCLUSIONS Oral administration of vancomycin significantly impacts host physiology by decreasing intestinal microbiota diversity, bile acid dehydroxylation and peripheral insulin sensitivity in subjects with metabolic syndrome. These data show that intestinal microbiota, particularly of the Firmicutes phylum contributes to bile acid and glucose metabolism in humans. This trial is registered at the Dutch Trial Register (NTR2566).

Pioglitazone Improves Cardiac Function and Alters Myocardial Substrate Metabolism Without Affecting Cardiac Triglyceride Accumulation and High-Energy Phosphate Metabolism in Patients With Well-Controlled Type 2 Diabetes Mellitus

Background— Cardiac disease is the leading cause of mortality in type 2 diabetes mellitus (T2DM). Pioglitazone has been associated with improved cardiac outcome but also with an elevated risk of heart failure. We determined the effects of pioglitazone on myocardial function in relation to cardiac high-energy phosphate, glucose, and fatty acid metabolism and triglyceride content in T2DM patients. Methods and Results— Seventy-eight T2DM men without structural heart disease or inducible ischemia as assessed by dobutamine stress echocardiography were assigned to pioglitazone (30 mg/d) or metformin (2000 mg/d) and matching placebo for 24 weeks. The primary end point was change in cardiac diastolic function from baseline relative to myocardial metabolic changes, measured by magnetic resonance imaging, proton and phosphorus magnetic resonance spectroscopy, and [18F]-2-fluoro-2-deoxy-d-glucose and [11C]palmitate positron emission tomography. No patient developed heart failure. Both therapies similarly improved glycemic control, whole-body insulin sensitivity, and blood pressure. Pioglitazone versus metformin improved the early peak flow rate (P=0.047) and left ventricular compliance. Pioglitazone versus metformin increased myocardial glucose uptake (P<0.001), but pioglitazone-related diastolic improvement was not associated with changes in myocardial substrate metabolism. Metformin did not affect myocardial function but decreased cardiac work relative to pioglitazone (P=0.006), a change that was paralleled by a reduced myocardial glucose uptake and fatty acid oxidation. Neither treatment affected cardiac high-energy phosphate metabolism or triglyceride content. Only pioglitazone reduced hepatic triglyceride content (P<0.001). Conclusions— In T2DM patients, pioglitazone was associated with improvement in some measures of left ventricular diastolic function, myocardial glucose uptake, and whole-body insulin sensitivity. The functional changes, however, were not associated with myocardial substrate and high-energy phosphate metabolism.

Diagnostic value of serum thyroglobulin measurements in the follow‐up of differentiated thyroid carcinoma, a structured meta‐analysis

objective  To investigate to what extent thyroid remnant ablation and withdrawal from thyroxine are required to achieve sufficient accuracy of serum thyroglobulin (Tg) measurements as an indicator of tumour recurrence in the follow‐up of patients with differentiated thyroid carcinoma.

Insulin Sensitivity and Insulin Clearance in Human Immunodeficiency Virus-Infected Men

To test whether clinically stable human immunodeficiency virus (HIV) infection, like other infections, is associated with insulin resistance and increased insulin clearance, we measured the sensitivity to insulin and insulin clearance using the euglycemic insulin clamp technique in 10 clinically stable outpatients with symptomatic HIV infection (Centers for Disease Control [CDC] group IV) and 10 healthy controls. During administration of 0.8 and 4 mU insulin.kg-1.min-1, HIV-infected men had 40% (P less than .02) and 83% (P less than .01) higher rates of insulin clearance when compared with healthy controls. Despite significantly lower steady-state insulin concentrations (42 +/- 2 v 52 +/- 4 microU/mL, P less than .05, and 255 +/- 17 v 392 +/- 14 microU/mL, P less than .001, patients v controls), patients and controls had similar total glucose uptake (7.99 +/- 0.81 v 7.92 +/- 0.44 mg.kg-1.min-1 and 14.00 +/- 0.81 v 13.65 +/- 0.65 mg.kg-1.min-1, patients v controls). In the postabsorptive state, no differences were found between patients and controls in insulin levels (7 +/- 1 microU/mL in both) and endogenous glucose production (2.52 +/- 0.07 and 2.24 +/- 0.17 mg.kg-1.min-1, respectively), but plasma glucose levels in the patients (5.02 +/- 0.15 mmol/L) were significantly lower when compared with controls (5.46 +/- 0.14 mmol/L, P less than .05). The results indicate that HIV-infected men have increased rates of insulin clearance and increased sensitivity of peripheral tissues to insulin, which makes HIV infection unique with regard to glucose and insulin metabolism.

Lipodystrophy in Hiv-1-positive patients is associated with insulin resistance in multiple metabolic pathways

BackgroundTreatment for HIV-1 infection is complicated by fat redistribution (lipodystrophy). This is associated with insulin resistance concerning glucose uptake. Our aim was to characterize glucose metabolism more comprehensively in HIV-1-infected patients with lipodystrophy. We assessed glucose disposal and its pathways, glucose production, plasma free fatty acid (FFA) levels, and the degree to which these parameters could be suppressed by insulin. MethodsSix HIV-1-infected men on protease inhibitor-based HAART with lipodystrophy (HIV+LD) were studied. The results were compared with those in six matched healthy male volunteers. Insulin sensitivity was quantified by hyperinsulinemic euglycaemic clamp. Glucose production and uptake were assessed by tracer dilution employing 6,6d2-glucose. ResultsAt post-absorptive insulin concentrations, glucose production was 47% higher in HIV+LD than controls (P = 0.025). During clamp, glucose production was suppressed by 53% in HIV+LD, but by 85% in controls (P = 0.004). Glucose disposal increased in both groups, but by only 27% in HIV+LD versus 201% in controls (P = 0.004). Consequently, insulin-stimulated total glucose disposal was lower in HIV+LD patients (P = 0.006). Non-oxidative glucose disposal as percentage of total disposal did not differ significantly between groups (63% in HIV+LD and 62% in controls). Baseline plasma FFA concentrations were higher (0.60 versus 0.35 mmol/l;P = 0.024), whereas FFA decline during hyperinsulinemia was less (65 versus 85%;P = 0.01) in HIV+LD versus controls . ConclusionsPost-absorptive glucose production is increased in HIV-1-infected patients with lipodystrophy. Moreover, both the ability of insulin to suppress endogenous glucose production and lipolysis, and to stimulate peripheral glucose uptake and its metabolic pathways is reduced, indicating severe resistance concerning multiple effects of insulin.

High prevalence of long‐term cardiovascular, neurological and psychosocial morbidity after treatment for craniopharyngioma

Introduction  The treatment of craniopharyngiomas is associated with long‐term morbidity.

Myocardial steatosis and biventricular strain and strain rate imaging in patients with type 2 diabetes mellitus.

Background— Magnetic resonance spectroscopy can quantify myocardial triglyceride content in type 2 diabetic patients. Its relation to alterations in left (LV) and right (RV) ventricular myocardial functions is unknown. Methods and Results— A total of 42 men with type 2 diabetes mellitus were recruited. Exclusion criteria included hemoglobin A1c >8.5%, known cardiovascular disease, diabetes-related complications, or blood pressure >150/85 mm Hg. Myocardial ischemia was excluded by a negative dobutamine stress test. LV and RV volumes and ejection fraction were quantified by magnetic resonance imaging. LV global longitudinal and RV free wall longitudinal strain, systolic strain rate, and diastolic strain rate were quantified by echocardiographic speckle tracking analyses. Myocardial triglyceride content was quantified by magnetic resonance spectroscopy and dichotomized on the basis of the median value of 0.76%. The median age was 59 years (25th and 75th percentiles, 54 and 62 years). Median diabetes diagnosis duration was 4 years, and median glycohemoglobin level was 6.2% (25th and 75th percentiles, 5.9% and 6.8%). There were no differences in LV and RV end-diastolic and end-systolic volume indexes and ejection fraction between patients with high (≥0.76%) and those with low (<0.76%) myocardial triglyceride content. However, patients with high myocardial triglyceride content had greater impairment of LV and RV myocardial strain and strain rate. The myocardial triglyceride content was an independent correlate of LV and RV longitudinal strain, systolic strain rate, and diastolic strain rate. Conclusions— High myocardial triglyceride content is associated with more pronounced impairment of LV and RV functions in men with uncomplicated type 2 diabetes mellitus.