Persistent Reduction of Circulating Myeloid Calcifying Cells in Acromegaly: Relevance to the Bone-Vascular Axis

CONTEXT

Acromegaly is a systemic disease characterized by persistent bone pathology and excess cardiovascular mortality. Despite multiple concomitant risk factors, atherosclerosis does not seem to be accelerated in acromegaly.

OBJECTIVE

To compare the levels of circulating myeloid calcifying cells (MCCs), which promote ectopic calcification and inhibit angiogenesis, in individuals with and without acromegaly.

DESIGN

Cross-sectional case-control study.

SETTING

Tertiary ambulatory referral endocrinology center.

PATIENTS

44 acromegalic patients (25 active; 19 inactive), 44 control subjects matched by age, sex, risk factors, and medications, and 8 patients cured of acromegaly.

INTERVENTION

MCCs were measured using flow cytometry based on the expression of osteocalcin (OC) and bone alkaline phosphatase (BAP) on monocytes and circulating CD34+ stem cells.

MAIN OUTCOME MEASURE

Differences in MCCs between patients and controls.

RESULTS

OC+BAP+ MCCs were severely reduced in acromegalic compared with control patients (0.17% ± 0.02% vs 1.00% ± 0.24%; P < 0.001), as were the total OC+ and BAP+ monocytic cells. Patients with inactive acromegaly and those cured of acromegaly displayed persistently reduced levels of MCCs. In the controls, but not acromegalic patients, MCCs were increased in the presence of diabetes or cardiovascular disease. A direct correlation was noted between MCCs and parathyroid hormone (r = 0.61; P < 0.0001), supporting a link between bone biology and MCCs.

CONCLUSIONS

In patients with acromegaly, the levels of MCCs are reduced and remain low, even years after a complete cure. This finding might be related to low atherosclerotic calcification and the persistence of bone pathology after acromegaly remission or cure.

Silent coronary heart disease in patients with type 2 diabetes: application of a screening approach in a follow-up study

AIMS

The cost-effectiveness of screening for silent coronary heart disease (CHD) in type 2 diabetes (DM2) is still debated.

METHODS

We applied a diagnostic algorithm for silent CHD detection, in a cohort of 102 asymptomatic DM2 subjects (57±7years), attending 5 Italian outpatient clinics, to verify its predictive value. The risk of silent CHD was calculated considering classical risk factors, and presence of microangiopathy/macroangiopathy. Patients were divided in 3 groups, i.e. group 1: normal ECG and low silent CHD risk; group 2: abnormal ECG, irrespective of silent CHD risk; group 3: high silent CHD risk, irrespective of ECG. To group 2 and 3, a functional test was recommended and performed in 78% of patients.

RESULTS

Silent CHD prevalence was similar in group 2 and 3 (25 vs. 17% respectively; p=0.495). However, evaluating the entire cohort, a significant higher prevalence of silent CHD was observed in subjects with abnormal vs. normal ECG (23 vs. 4%; P=0.004), but not in subjects with high vs. low pre-test silent CHD risk (14 vs. 9%; p=0.472).

CONCLUSIONS

An abnormal ECG was a strong, independent predictor of silent CHD (OR 8.9; CI 1.27-62.5; p=0.028) in DM2. Therefore, a functional stress testing should be considered in DM2 patients with ECG abnormalities.

Hypovitaminosis D is associated with erectile dysfunction in type 2 diabetes

Diabetes is an established risk factor for erectile dysfunction (ED). The pathophysiology of ED in diabetic men is multifactorial, but it mainly involves a vascular disorder related to a reduction of endothelial function. Recently, several studies have correlated ED risk factors with vitamin D deficiency. In this study, we evaluate the relationship between 25-hydroxyvitamin D [25(OH)D] levels, erectile dysfunction, and vascular disease, in type 2 diabetes mellitus men (T2DM). In this observational study, 92 T2DM males (58.83 ± 9.73 years) underwent medical history collection, International Index of Erectile Function (IIEF-5) questionnaire, that allows the identification and grading of DE, physical examination, biochemical/hormonal blood tests, and penile echo-color Doppler ultrasonography. T2DM patients with lower 25(OH)D levels (<25 nmol/l) showed higher penile IMT (p < 0.05), waist circonference (p < 0.05), glucose concentrations (p < 0.05), and lower IIEF-5 score (p < 0.005), testosterone concentrations (p < 0.05), and cavernous peak systolic velocity (PSV) (p < 0.05), compared to patients with 25(OH)D >50 nmol/l. 25(OH)D levels were directly correlated with IIEF-5 (R = 0.39; p = 0.0001), testosterone (R = 0.24; p = 0.02), and PSV (R = 0.24; p = 0.04) and inversely with waist (R = -0.33; p = 0.002), HbA1c (R = -0.22; p = 0.03), triglyceride (R = -0.21; p = 0.06), and penile IMT (R = -0.30; p = 0.009). At multivariate analysis, 25(OH)D deficiency remained an independent predictor of DE. We demonstrate a significant association between 25(OH)D deficiency and erectile dysfunction in T2DM men. This association may be due to the influence of 25(OH)D deficiency on cardiovascular risk factor (glycaemia, HDL cholesterol, and triglycerides), testosterone plasma levels and endothelial dysfunction.

NETosis Delays Diabetic Wound Healing in Mice and Humans

Upon activation, neutrophils undergo histone citrullination by protein arginine deiminase (PAD)4, exocytosis of chromatin and enzymes as neutrophil extracellular traps (NETs), and death. In diabetes, neutrophils are primed to release NETs and die by NETosis. Although this process is a defense against infection, NETosis can damage tissue. Therefore, we examined the effect of NETosis on the healing of diabetic foot ulcers (DFUs). Using proteomics, we found that NET components were enriched in nonhealing human DFUs. In an independent validation cohort, a high concentration of neutrophil elastase in the wound was associated with infection and a subsequent worsening of the ulcer. NET components (elastase, histones, neutrophil gelatinase-associated lipocalin, and proteinase-3) were elevated in the blood of patients with DFUs. Circulating elastase and proteinase-3 were associated with infection, and serum elastase predicted delayed healing. Neutrophils isolated from the blood of DFU patients showed an increased spontaneous NETosis but an impaired inducible NETosis. In mice, skin PAD4 activity was increased by diabetes, and FACS detection of histone citrullination, together with intravital microscopy, showed that NETosis occurred in the bed of excisional wounds. PAD4 inhibition by Cl-amidine reduced NETting neutrophils and rescued wound healing in diabetic mice. Cumulatively, these data suggest that NETosis delays DFU healing.

Carotid plaque calcification predicts future cardiovascular events in type 2 diabetes

OBJECTIVE

The presence of carotid plaques is associated with future cardiovascular events, with local plaque composition being an independent outcome predictor. We examined the association between ultrasonographically determined carotid plaque calcification and incident major adverse cardiovascular events (MACE) and death in type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

We enrolled 581 patients with T2D who underwent routine carotid ultrasonography. Plaques were classified as echolucent (lipid rich), heterogenous, and echogenic (calcific). We collected demographic, anthropometric, and clinical data at baseline and followed the patients for up to 9 years.

RESULTS

Plaques were detected in 81.8% of the patients (echolucent in 16.4%, heterogenous in 43.2%, and echogenic in 22.2%). During follow-up (4.3 ± 0.1 years), 58 deaths (27 cardiovascular) and 236 fatal and nonfatal MACE occurred. In univariate analyses, presence versus absence of any carotid plaque was associated with incident MACE, and the hazard ratio (95% CI) progressively increased from echolucent (1.97 [0.93-3.44]), to heterogeneous (3.10 [2.09-4.23]), to echogenic (3.71 [2.09-5.59]) plaques. Compared with echolucent plaques, echogenic plaques were associated with incident MACE independently from confounders. This association was attenuated after adjusting for the degree of stenosis, but in patients with stenosis ≤30%, echogenic plaque type still predicted total and atherosclerotic MACE, even after further adjusting for mean intima-media thickness.

CONCLUSIONS

In T2D, carotid plaque calcification predicts MACE, especially in patients with a low degree of stenosis. The biology of atherosclerotic calcification in diabetes needs to be further elucidated to understand the basis of this association.

NETosis is induced by high glucose and associated with type 2 diabetes

AIMS

The role of neutrophils in diabetes and its complications is unclear. Upon challenge with microbes and inflammatory triggers, neutrophils release enzymes and nuclear material, forming neutrophils extracellular traps (NETs) and thereby dying by NETosis. We herein tested NET formation and NETosis products in high glucose and in the setting of type 2 diabetes (T2D).

METHODS

NETosis was assessed in vitro in cells exposed to 0, 5, 25 mM glucose and 25 mM mannitol, DMSO and PMA using immunofluorescence staining for elastase, DNA and chromatin. Single-cell morphometric analysis was used to detect enter of elastase in the nucleus and extrusion of nuclear material. Release of NETs was quantified by staining with Hoechst 33342. In 38 T2D and 38 age- and sex-matched non-diabetic individuals, we determined plasma elastase, mono- and oligonucleosomes and double-strand (ds) DNA, as circulating NETosis products.

RESULTS

NETosis was accurately reproduced in vitro: high (25 mM) glucose increased NETosis rate and release of NETs compared with 5 mM glucose and 25 mM mannitol. T2D patients showed increased plasma elastase, mono- and oligonucleosomes and dsDNA compared with non-diabetic control individuals. A positive correlation was found between HbA1c and mono- and oligonucleosomes, whereas dsDNA was correlated with the presence of nephropathy and cardiovascular disease. Serum IL-6 concentrations were higher in T2D compared with CTRL and correlated with serum dsDNA levels.

CONCLUSIONS

High glucose and hyperglycemia increase release of NETs and circulating markers of NETosis, respectively. This finding provides a link among neutrophils, inflammation and tissue damage in diabetes.

NAD(+)-dependent SIRT1 deactivation has a key role on ischemia-reperfusion-induced apoptosis

Ischemia-reperfusion (IR) leads to severe organ injury and dysfunction. Sirtuins (SIRTs) are a family of histone deacetylases (HDACs) that require nicotinamide adenine dinucleotide (NAD(+)) for the deacetylation reaction. SIRTs play a major role in counteracting cellular stress and apoptosis. This study aimed to investigate the mechanisms of heart protection against apoptosis by SIRTs and the molecular pathways involved in SIRTs regulation and function in a rat model of IR injury. Hearts of male Wistar-Kyoto rats were subjected to 30-min ischemia followed by reperfusion up to 6h. IR increased cardiomyocyte apoptosis; the cleavage of caspase 3, induced a transient upregulation of SIRT1 and downregulation of SIRT6 expression, but decreased SIRT1 activity and reduced NAD(+) content. IR also increased forkhead box protein O1 (FoxO1) expression and FoxO1 binding to SIRT1 promoter region. Resveratrol restored SIRT1 activity and NAD(+) level by an AMPK-dependent mechanism, reduced cardiomyocyte apoptosis, and attenuated caspase 3 cleavage via heat shock factor-1 deacetylation and heat shock protein (HSP) expression upregulation. Our data show new potential molecular mechanisms of up and downstream regulation of SIRT1 in IR. The interplay among FoxO1, SIRT1, NAD(+), AMPK, HSP, and SIRT6 depicts a complex molecular network that protects the heart from apoptosis during IR and may be susceptible to therapeutic interventions.

Endothelial progenitor cells are reduced in acromegalic patients and can be restored by treatment with somatostatin analogs

CONTEXT

Acromegaly increases cardiovascular risk, possibly due to the high prevalence of classical risk factors. However, in vitro studies show a protective role of GH/IGF-1 on the endothelium.

OBJECTIVE

The objective of the study was to investigate circulating endothelial progenitor cells (EPCs), a marker of vascular regeneration, in acromegalic patients and how they are affected by acromegaly treatment.

DESIGN

This was a cross-sectional case-control and observational study.

SETTING

The study was conducted at a tertiary ambulatory referral endocrinology center.

PATIENTS

Forty-three acromegalic patients (26 active; 17 inactive) and 43 control subjects matched by age, gender, and degree of glucose tolerance participated in the study.

INTERVENTION

Circulating EPCs were quantified by flow cytometry based on the expression of CD34, CD133, and kinase insert domain-containing receptor (KDR). Nine patients with active acromegaly were reevaluated after 24 weeks of treatment with somatostatin analogs (SSAs).

MAIN OUTCOME MEASURE

Differences in EPC levels between patients and controls were measured.

RESULTS

Acromegalic patients showed a significant reduction of the total CD34(+)KDR(+) EPC population compared with controls, which was more evident in patients without diabetes or hypertension. More definite CD34(+)CD133(+)KDR(+) EPCs were reduced in patients with active compared with those with inactive acromegaly and compared with controls. The number of CD34(+)CD133(+)KDR(+) EPCs correlated with IGF-1 levels (r = -0.45; P < .001), fasting plasma glucose (r = -0.40; P = .004), and the homeostasis model assessment index of insulin resistance (r = -0.32; P = .026). CD34(+)CD133(+)KDR(+) EPCs increased 2-fold after SSA treatment.

CONCLUSIONS

Acromegalic patients have a reduced endothelial regenerative capacity, possibly due to activation of the GH/IGF-1, rather than concomitant risk factors. Treatment with SSAs can restore immature EPCs to normal levels.

Pro-inflammatory monocyte-macrophage polarization imbalance in human hypercholesterolemia and atherosclerosis

Monocyte-macrophages (MoMas) play a major role in atherosclerosis. In mice, hypercholesterolemia increases pro-inflammatory monocytes that promote plaque growth, but whether this is true also in humans in unknown. We herein analyzed monocyte subsets and MoMa phenotypes in familiar (FH, n = 22) and non-familiar (NFH, n = 20) hypercholesterolemic compared with normocholesterolemic (CTRL, n = 20) patients. We found that FH and NFH had higher circulating pro-inflammatory CD68(+)CCR2(+) M1 MoMas than CTRL, while anti-inflammatory CX3CR1(+)CD163(+)/CD206(+) M2 MoMas were reduced only in NFH. As a result, the M1/M2 polarization balance was increased in FH and, more markedly in NFH. M1 MoMas and the M1/M2 polarization ratio were directly correlated to pre-treatment LDL cholesterol levels and strongly associated with the presence of atherosclerotic plaques. In conclusion, we show for the first time that human hypercholesterolemia is associated with a pro-inflammatory imbalance of circulating monocytic cells, which can predispose to the development of atherosclerosis.

Insulin-induced glucose control improves HDL cholesterol levels but not reverse cholesterol transport in type 2 diabetic patients

Type 2 diabetes (T2D) is characterized by low HDL cholesterol (HDL-C) and HDL dysfunction. We herein tested whether lowering HbA1c affects HDL-C and reverse cholesterol transport (RCT). Forty-two uncontrolled T2D patients initiating basal insulin were included. HbA1c, HDL-C and RCT were assessed at baseline and after 6 months. At baseline, HDL-C and RCT were directly correlated (r = 0.50; p < 0.001). After 6 months of insulin therapy, HbA1c dropped from 8.8 ± 0.16% to 7.1 ± 0.1%, while average HDL-C and RCT did not change. Follow-up HDL-C and RCT were still correlated (r = 0.31; p = 0.033) and ΔHDL-C correlated with ΔRCT (r = 0.32; p = 0.029). ΔHbA1c correlated with ΔHDL-C (r = 0.43, p = 0.001), but not with ΔRCT. In patients with ΔHbA1c above the median value (1.3%), HDL-C (but not RCT) increased significantly. In conclusion, glucose control correlates with increased HDL-C, but not with improved RCT. Thus, persistent HDL dysfunction despite improved HbA1c and HDL-C can contribute to residual cardiovascular risk in T2D.

Diabetes causes bone marrow autonomic neuropathy and impairs stem cell mobilization via dysregulated p66Shc and Sirt1

Diabetes compromises the bone marrow (BM) microenvironment and reduces the number of circulating CD34(+) cells. Diabetic autonomic neuropathy (DAN) may impact the BM, because the sympathetic nervous system is prominently involved in BM stem cell trafficking. We hypothesize that neuropathy of the BM affects stem cell mobilization and vascular recovery after ischemia in patients with diabetes. We report that, in patients, cardiovascular DAN was associated with fewer circulating CD34(+) cells. Experimental diabetes (streptozotocin-induced and ob/ob mice) or chemical sympathectomy in mice resulted in BM autonomic neuropathy, impaired Lin(-)cKit(+)Sca1(+) (LKS) cell and endothelial progenitor cell (EPC; CD34(+)Flk1(+)) mobilization, and vascular recovery after ischemia. DAN increased the expression of the 66-kDa protein from the src homology and collagen homology domain (p66Shc) and reduced the expression of sirtuin 1 (Sirt1) in mice and humans. p66Shc knockout (KO) in diabetic mice prevented DAN in the BM, and rescued defective LKS cell and EPC mobilization. Hematopoietic Sirt1 KO mimicked the diabetic mobilization defect, whereas hematopoietic Sirt1 overexpression in diabetes rescued defective mobilization and vascular repair. Through p66Shc and Sirt1, diabetes and sympathectomy elevated the expression of various adhesion molecules, including CD62L. CD62L KO partially rescued the defective stem/progenitor cell mobilization. In conclusion, autonomic neuropathy in the BM impairs stem cell mobilization in diabetes with dysregulation of the life-span regulators p66Shc and Sirt1.

Cardiovascular actions of GLP-1 and incretin-based pharmacotherapy

Incretin-based therapy became recently available as antihyperglycemic treatment for patients with type 2 diabetes (T2DM). Incretin therapy comprises glucagon-like peptide receptor agonists (GLP-1RA) and dipeptidyl-peptidase 4 inhibitors (DPP4-I): these classes of drugs not only have the ability to reduce blood glucose, but also can exert several cardioprotective effects. They have been shown to positively influence some risk factors for cardiovascular disease (CVD), to improve endothelial function, and to directly affect cardiac function. For these reasons incretins are considered not only antidiabetic drugs, but also cardiovascular effective. The first clinical trials aimed to demonstrate the safety of DPP4 inhibitors have been recently published: their clinical significance will be discussed in light of the prior experimental findings.

Monocyte-macrophage polarization balance in pre-diabetic individuals

Pre-diabetes is characterized by increased cardiovascular risk and chronic inflammation. The activation of monocyte-macrophages plays major roles in vascular biology. Herein, we aimed to analyze monocyte-macrophage polarization status in subjects with IFG and/or IGT compared with normal glucose tolerant (NGT) individuals. We enrolled 87 middle-aged individuals with low prevalence of cardiovascular disease. Based on OGTT, they were divided into 49 NGT and 38 pre-diabetic (IFG and/or IGT). Using flow cytometry analysis of peripheral blood cells, we quantified traditional monocyte subsets based on CD14 and CD16 expression as well as novel monocyte-macrophage pro-inflammatory CD68(+)CCR2(+) M1 and anti-inflammatory CX3CR1(+)CD163(+)/CD206(+) M2 phenotypes. The M1/M2 ratio was taken to represent the polarization balance. There were no differences in traditional classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)) and nonclassical (CD14(+)CD16(+)) monocytes between groups. Rather, compared to NGT, pre-diabetic subjects showed a significant increase in pro-inflammatory M1 cells and percent expression of the oxLDL scavenger receptor CD68, without changes in anti-inflammatory M2 cells. M1 levels and CD68 expression were directly correlated with HbA1c. We show for the first time that otherwise healthy pre-diabetic subjects have excess M1 inflammatory cells in peripheral blood, which may contribute to cardiovascular risk.

Diabetes impairs stem cell and proangiogenic cell mobilization in humans

OBJECTIVE

Diabetes mellitus (DM) increases cardiovascular risk, at least in part, through shortage of vascular regenerative cells derived from the bone marrow (BM). In experimental models, DM causes morphological and functional BM alterations, but information on BM function in human DM is missing. Herein, we sought to assay mobilization of stem and proangiogenic cells in subjects with and without DM.

RESEARCH DESIGN AND METHODS

In a prospective trial (NCT01102699), we tested BM responsiveness to 5 μg/kg human recombinant granulocyte colony-stimulating factor (hrG-CSF) in 24 individuals with DM (10 type 1 and 14 type 2) and 14 individuals without DM. Before and 24 h after hrG-CSF, we quantified circulating stem/progenitor cells and total and differential white blood cell counts. We also evaluated in vivo the proangiogenic capacity of peripheral blood mononuclear cells using the Matrigel plug assay.

RESULTS

In response to hrG-CSF, levels of CD34(+) cells and other progenitor cell phenotypes increased in subjects without DM. Patients with DM had significantly impaired mobilization of CD34(+), CD133(+), and CD34(+)CD133(+) hematopoietic stem cells and CD133(+)KDR(+) endothelial progenitors, independently of potential confounders. The in vivo angiogenic capacity of peripheral blood mononuclear cells significantly increased after hrG-CSF in control subjects without DM, but not in patients with DM. DM was also associated with the inability to upregulate CD26/DPP-4 on CD34(+) cells, which is required for the mobilizing effect of granulocyte colony-stimulating factor.

CONCLUSIONS

Stem and proangiogenic cell mobilization in response to hrG-CSF is impaired in DM, possibly because of maladaptive CD26/DPP-4 regulation. These alterations may hamper tissue repair and favor the development of cardiovascular complications.

Elevated white blood cell count is associated with prevalence and development of the metabolic syndrome and its components in the general population

The metabolic syndrome (MS) is characterized by chronic inflammation. We aimed to determine the association of white blood cell (WBC) count with prevalence and development of the MS and its components in the general population. A cohort of 1,329 subjects from the local working population aged 41.3 ± 7.5 years and recruited since 2000-2008 was followed up for 4.0 ± 1.2 years. WBC count and MS components were determined at baseline and follow-up. To determine whether WBC predicted incident MS, we used a logistic regression analysis adjusted for demographics, baseline variables that define MS components, smoke, medications, and follow-up duration. Cross-sectionally in the whole population, WBC count increased in parallel with the number of MS components in the same individual, and the presence of each component was associated with higher WBC count. Baseline WBC count was significantly higher in subjects with prevalent MS. Among subjects without MS at baseline, those who developed MS had significantly higher WBC than those who did not develop MS at follow-up. Development of each MS component was associated with increased WBC count. WBC count remained significantly associated with MS development after correction for several potential confounders (OR for 1 SD increase in WBC 1.26; 95 % CI 1.01-1.58). In conclusion, elevated WBC is intimately linked to the prevalence and future development of the MS in a young population of working subjects.

Characteristics and outcomes of the hyperglycemic hyperosmolar non-ketotic syndrome in a cohort of 51 consecutive cases at a single center

AIMS

The hyperglycemic hyperosmolar syndrome (HHS) is a life-threatening diabetic complication. We aimed to portrait the short and long term outcome after a HHS episode and to describe features associated with increased early mortality.

METHODS

We collected data from consecutive HHS cases, defined based on rigorous glucose and osmolality criteria. We retrieved anthropometric measures, history of diabetes, other cardiovascular risk factors and chronic co-morbidity. Clinical and biochemical parameters were recorded at admission, after 24h and at discharge. We assessed incidence of complications, as well as short (≤ 30 days) and long term mortality.

RESULTS

Patients were about 80-year old. Fifty-one cases were included, characterized by severe hyperglycemia (55.5 mosm/L) and hyperosmolality (385 mosm/L). Thirty-three percent developed at least one complication. Short term mortality was 16%; lower Glasgow Coma Scale, higher plasma glucose and mild acidosis were predictive of short term mortality. The long term mortality (median follow-up 1.27 years) was not significantly different from historical mortality data after hypoglycemic coma.

CONCLUSION

In this study, early mortality of HHS was 16% and some clinical features at presentation were predictive of an adverse short term outcome. Long term survival after a HHS episode did not appear to be severely impaired.

The metabolic syndrome influences the response to incretin-based therapies

We hypothesize that type 2 diabetic patients with different phenotypes may show different response to incretin-based therapies. Therefore, we tested whether the presence of metabolic syndrome (MS) influences glycemic response to these drugs. We prospectively followed 211 patients, treated with the GLP-1 analog exenatide (n = 102) or a DPP-4 inhibitor (n = 109) for at least 4 months. Treatment was decided on clinical grounds. We collected baseline data (age, sex, BMI, waist, systolic and diastolic blood pressure, lipid profile, data on diabetic complications and concomitant treatment) and HbA1c at subsequent visits. Patients were divided into groups according to the presence/absence of MS. Compared to patients on exenatide, patients on DPP-4 inhibitors were older and had lower BMI, waist, diastolic blood pressure, fasting plasma glucose, and HbA1c. At means of baseline values, HbA1c reduction was similar in patients treated with exenatide or DPP-4 inhibitors. Patients on exenatide showed significantly higher HbA1c reduction if they had MS (-1.55 ± 0.22%; n = 88) than if they had not (-0.34 ± 0.18%; P = 0.002). Conversely, patients on DPP-4 inhibitors showed significantly lower HbA1c reduction if they had MS (-0.60 ± 0.12%; n = 73) than if they had not (-1.50 ± 0.24%; P < 0.001). Type of MS definition (ATP-III, IDF or WHO) poorly influenced these trends. The interaction between type of therapy (exenatide vs. DPP-4 inhibitors) and MS remained significant after adjusting for age, baseline HbA1c, BMI, and concomitant medications. In conclusion, the presence of MS appears to modify the response to incretin-based therapies. Given the non-randomized nature of this study, these data need to be replicated.

Hemodynamics assessed via approximate entropy analysis of impedance cardiography time series: effect of metabolic syndrome

The metabolic syndrome (MS), a predisposing condition for cardiovascular disease, presents disturbances in hemodynamics; impedance cardiography (ICG) can assess these alterations. In subjects with MS, the morphology of the pulses present in the ICG time series is more irregular/complex than in normal subjects. Therefore, the aim of the present study was to quantitatively assess the complexity of ICG times series in 53 patients, with or without MS, through a nonlinear analysis algorithm, the approximate entropy, a method employed in recent years for the study of several biological signals, which provides a scalar index, ApEn. We correlated ApEn computed from ICG times series data during fasting and postprandial phase with the presence of alterations in the parameters defining MS [Adult Treatment Panel (ATP) III (Grundy SM, Brewer HB Jr, Cleeman JI, Smith SC Jr, Lenfant C; National Heart, Lung, and Blood Institute; American Heart Association. Circulation 109: 433–438, 2004) and the International Diabetes Federation (IDF) definition]. Results show that ApEn was significantly higher in subjects with MS compared with those without (1.81 ± 0.09 vs. 1.65 ± 0.13; means ± SD; P = 0.0013, with ATP III definition; 1.82 ± 0.09 vs. 1.67 ± 0.12; P = 0.00006, with the IDF definition). We also demonstrated that ApEn increase parallels the number of components of MS. ApEn was then correlated to each MS component: mean ApEn values of subjects belonging to the first and fourth quartiles of the distribution of MS parameters were statistically different for all parameters but HDL cholesterol. No difference was observed between ApEn values evaluated in fasting and postprandial states. In conclusion, we identified that MS is characterized by an increased complexity of ICG signals: this may have a prognostic relevance in subjects with this condition.

Impaired hemodynamic response to meal intake in insulin-resistant subjects: an impedance cardiography approach

BACKGROUND

In the postprandial state, insulin regulates metabolic and cardiovascular responses. In insulin resistance, the insulin action is impaired at both levels. However, postprandial hemodynamic responses are poorly characterized in this setting.

OBJECTIVE

We investigated fasting and postprandial cardiac and vascular hemodynamic responses in subjects with and without insulin resistance.

DESIGN

Sixty-six atherosclerosis-free, healthy volunteers were studied in a fasted state and ≤180 min after ingestion of a mixed meal. The insulin sensitivity index was determined by using a minimal model analysis; hemodynamic response was monitored by using continuous impedance cardiography that allowed a reliable beat-to-beat noninvasive evaluation of stroke volume, cardiac contractility, and several derived variables.

RESULTS

Subjects were divided into insulin-resistant (IR; n = 33) and insulin-sensitive (IS; n = 33) groups. After fasting, IR subjects had significantly higher values of systolic and diastolic blood pressures and the systemic vascular resistance index (SVRI) than did IS subjects. In the postprandial state, acute vasodilatation was comparable and synchronous (at 30 min) in IR and IS subjects (P = 0.209), but subsequent vascular tone recovery (30-180 min) was significantly impaired in IR subjects (P = 0.018), even after adjustment for age and sex (P = 0.031). Hemodynamic dysregulation was directly correlated with metabolic disturbances in the postprandial state. In basal and postprandial states, hemodynamic variables related to cardiac function were not significantly different in IR and IS subjects.

CONCLUSIONS

IR subjects had a worse fasting vascular performance than did IS subjects. In the postprandial phase, insulin resistance was associated with a shorter duration of vasodilatation in the absence of an altered cardiac performance. Peripheral hemodynamic alterations in fasting and postprandial states may have a negative effect on cardiovascular performance in IR patients.

Widespread increase in myeloid calcifying cells contributes to ectopic vascular calcification in type 2 diabetes

RATIONALE

Acquisition of a procalcific phenotype by resident or circulating cells is important for calcification of atherosclerotic plaques, which is common in diabetes.

OBJECTIVE

We aim to identify and characterize circulating calcifying cells, and to delineate a pathophysiological role for these cells in type 2 diabetes.

METHODS AND RESULTS

We demonstrate for the first time that a distinct subpopulation of circulating cells expressing osteocalcin and bone alkaline phosphatase (OC(+)BAP(+)) has procalcific activity in vitro and in vivo. The study of naïve patients with chronic myeloid leukemia indicated that OC(+)BAP(+) cells have a myeloid origin. Myeloid calcifying OC(+)BAP(+) cells (MCCs) could be differentiated from peripheral blood mononuclear cells, and generation of MCCs was closely associated with expression of the osteogenic transcription factor Runx2. In gender-mismatched bone marrow-transplanted humans, circulating MCCs had a much longer half-life compared with OC(-)BAP(-) cells, suggesting they belong to a stable cell repertoire. The percentage of MCCs was higher in peripheral blood and bone marrow of type 2 diabetic patients compared with controls but was lowered toward normal levels by optimization of glycemic control. Furthermore, diabetic carotid endoarterectomy specimens showed higher degree of calcification and amounts of cells expressing OC and BAP in the α-smooth muscle actin-negative areas surrounding calcified nodules, where CD68(+) macrophages colocalize. High glucose increased calcification by MCCs in vitro, and hypoxia may regulate MCC generation in vitro and in vivo.

CONCLUSIONS

These data identify a novel type of blood-derived procalcific cells potentially involved in atherosclerotic calcification of diabetic patients.

Exon 11 deletion in the myocyte enhancer factor (MEF)2A and early onset coronary artery disease gene in a Sicilian family

AIMS

We investigated the prevalence of the myocyte enhancer factor (MEF)2A exon 11 deletion, a putative coronary artery disease (CAD) susceptibility gene, in patients referred for coronary angiography.

METHODS AND RESULTS

In total, 1079 consecutive patients referred for coronary angiography in the GENICA Study were genotyped and 301 low-risk subjects were used as controls. One patient with early onset three vessels CAD, carrying the MEF2A deletion was found in the GENICA Study cohort and none in the control group.

CONCLUSION

In a cohort of patients undergoing coronary angiography for suspected CAD the MEF2A exon 11 deletion occurred in 0.09%.