Endothelium, inflammation, and diabetes

Photoperiod Conditions Modulate Serum Oxylipins Levels in Healthy and Obese Rats: Impact of Proanthocyanidins and Gut Microbiota

Seasonal rhythms are emerging as a key factor influencing gut microbiota and bioactive compounds functionality as well as several physiological processes such as inflammation. In this regard, their impact on the modulation of oxylipins (OXLs), which are important lipid mediators of inflammatory processes, has not been investigated yet. Hence, we aimed to investigate the effects of photoperiods on OXLs metabolites in healthy and obesogenic conditions. Moreover, we evaluated if the impact of proanthocyanidins and gut microbiota on OXLs metabolism is influenced by photoperiod in obesity. To this purpose, Fischer 344 rats were housed under different photoperiod conditions (L6: 6 h light, L12: 12 h light or L18:18 h light) and fed either a standard chow diet (STD) or a cafeteria diet (CAF) for 9 weeks. During the last 4 weeks, obese rats were daily administered with an antibiotic cocktail (ABX), an oral dose of a grape seed proanthocyanidin extract (GSPE), or with their combination. CAF feeding and ABX treatment affected OXLs in a photoperiod dependent-manner. GSPE significantly altered prostaglandin E2 (PGE2) levels, only under L6 and mitigated ABX-mediated effects only under L18. In conclusion, photoperiods affect OXLs levels influenced by gut microbiota. This is the first time that the effects of photoperiod on OXLs metabolites have been demonstrated.

Cerebral arterial architectonics and CFD simulation in mice with type 1 diabetes mellitus of different duration

Type 1 diabetes is a chronic autoimmune disease that affects tens of millions of people. Diabetes mellitus is one of the strongest factors in the development of cerebrovascular diseases. In this study we used NOD.CB17 Prkdcscid mice and the pharmacological model of type 1 diabetes mellitus of different duration to study changes in the cerebral vasculature. We used two combined approaches using magnetic resonance angiography both steady and transient CFD blood flow modeling. We identified the influence of type 1 diabetes on the architectonics and hemodynamics of the large blood vessels of the brain as the disease progresses. For the first time, we detected a statistically significant change in angioarchitectonics (the angles between the vessels of the circle of Willis, cross-sections areas of vessels) and hemodynamic (maximum blood flow rate, hydraulic resistance) in animals with diabetes duration of 2 months, that is manifested by the development of asymmetry of cerebral blood flow. The result shows the negative effect of diabetes on cerebral circulation as well as the practicability of CFD modeling. This may be of extensive interest, in pharmacological and preclinical studies.

Overview of Therapeutic Inertia in Diabetes: Prevalence, Causes, and Consequences

Many people with diabetes do not achieve individualized treatment targets. Therapeutic inertia, the underuse of effective therapies in preventing serious clinical end points, is a frequent, important contributor to this failure. Clinicians, patients, health systems, payors, and producers of medications, devices, and other products for those with diabetes all play a role in the development of therapeutic inertia and can all help to reduce it.

High glucose/High Lipids impair vascular adiponectin function via inhibition of caveolin-1/AdipoR1 signalsome formation

Reduced levels of adiponectin (APN) contribute to cardiovascular injury in the diabetic population. Recent studies demonstrate elevated circulating APN levels are associated with endothelial dysfunction during pre-diabetes, suggesting the development of APN resistance. However, mechanisms leading to, and the role of, vascular APN resistance in endothelial dysfunction remain unidentified. The current study determined whether diabetes cause endothelial APN resistance, and by what mechanisms. Under high glucose/high lipids (HG/HL), APN-stimulated nitric oxide production by HUVEC was decreased, phosphorylation of eNOS, AMPK, and Akt was attenuated (P<0.01), and APN's anti-TNFα effect was blunted (P<0.01). APN receptor expression remained normal, whereas Cav1 expression was reduced in HG/HL cells (P<0.01). The AdipoR1/Cav1 signaling complex was dissociated in HG/HL cells. Knock-down of Cav1 inhibited APN's anti-oxidative and anti-inflammatory actions. Conversely, preventing HG/HL-induced Cav1 downregulation by Cav1 overexpression preserved APN signaling in HG/HL cells. Knock-in of a wild type Cav1 in Cav1 knock-down cells restored caveolae structure and rescued APN signaling. In contrast, knock-in of a mutated Cav1 scaffolding domain restored caveolae structure, but failed to rescue APN signaling in Cav1 knock-down cells. Finally, AdipoR1/Cav1 interaction was significantly reduced in diabetic vascular tissue, and the vasorelaxative response to APN was impaired in diabetic animals. The current study demonstrates for the first time the interaction between AdipoR1 and Cav1 is critical for adiponectin-mediated vascular signaling. The AdipoR1/Cav1 interaction is adversely affected by HG/HL, due largely to reduced Cav1 expression, supporting a potential mechanism for the development of APN resistance, contributing to diabetic endothelial dysfunction.

Delay in treatment intensification increases the risks of cardiovascular events in patients with type 2 diabetes

BACKGROUND

The aim of the study was to evaluate the effect of delay in treatment intensification (IT; clinical inertia) in conjunction with glycaemic burden on the risk of macrovascular events (CVE) in type 2 diabetes (T2DM) patients.

METHODS

A retrospective cohort study was carried out using United Kingdom Clinical Practice Research Datalink, including T2DM patients diagnosed from 1990 with follow-up data available until 2012.

RESULTS

In the cohort of 105,477 patients mean HbA1c was 8.1% (65 mmol/mol) at diagnosis, 11% had a history of cardiovascular disease, and 7.1% experienced at least one CVE during 5.3 years of median follow-up. In patients with HbA1c consistently above 7/7.5% (53/58 mmol/mol, n = 23,101/11,281) during 2 years post diagnosis, 26/22% never received any IT. Compared to patients with HbA1c <7% (<53 mmol/mol), in patients with HbA1c ≥7% (≥53 mmol/mol), a 1 year delay in receiving IT was associated with significantly increased risk of MI, stroke, HF and composite CVE by 67% (HR CI: 1.39, 2.01), 51% (HR CI: 1.25, 1.83), 64% (HR CI: 1.40, 1.91) and 62% (HR CI: 1.46, 1.80) respectively. One year delay in IT in interaction with HbA1c above 7.5% (58 mmol/mol) was also associated with similar increased risk of CVE.

CONCLUSIONS

Among patients with newly diagnosed T2DM, 22% remained under poor glycaemic control over 2 years, and 26% never received IT. Delay in IT by 1 year in conjunction with poor glycaemic control significantly increased the risk of MI, HF, stroke and composite CVE.

Pathogenesis of diabetic cerebral vascular disease complication

Diabetes mellitus is one of the most potent independent risk factors for the development of diabetic cerebral vascular disease (CVD). Many evidences suggested that hyperglycemia caused excess free fatty acids, the loss of endothelium-derived nitric oxide, insulin resistance, the prothrombotic state, endothelial dysfunction, the abnormal release of endothelial vasoactivators, vascular smooth muscle dysfunction, oxidative stress, and the downregulation of miRs participated in vessel generation and recovery as well as the balance of endotheliocytes. In turn, these abnormalities, mainly via phosphatidylinositol 3 kinase, mitogen-activated protein kinase, polyol, hexosamine, protein kinase C activation, and increased generation of advanced glycosylation end products pathway, play an important role in inducing diabetic CVD complication. A deeper comprehension of pathogenesis producing diabetic CVD could offer base for developing new therapeutic ways preventing diabetic CVD complications, therefore, in the paper we mainly reviewed present information about the possible pathogenesis of diabetic CVD complication.

Cardiovascular dysfunction in obesity and new diagnostic imaging techniques: the role of noninvasive image methods

Obesity is a major public health problem affecting adults and children in both developed and developing countries. This condition often leads to metabolic syndrome, which increases the risk of cardiovascular disease. A large number of studies have been carried out to understand the pathogenesis of cardiovascular dysfunction in obese patients. Endothelial dysfunction plays a key role in the progression of atherosclerosis and the development of coronary artery disease, hypertension and congestive heart failure. Noninvasive methods in the field of cardiovascular imaging, such as measuring intima-media thickness, flow-mediated dilatation, tissue Doppler, and strain, and strain rate, constitute new tools for the early detection of cardiac and vascular dysfunction. These techniques will certainly enable a better evaluation of initial cardiovascular injury and allow the correct, timely management of obese patients. The present review summarizes the main aspects of cardiovascular dysfunction in obesity and discusses the application of recent noninvasive imaging methods for the early detection of cardiovascular alterations.

Influence of diabetes on endothelial cell response during sepsis

AIMS/HYPOTHESIS

Several endothelial pathways of cell adhesion, coagulation and vascular endothelial growth factor (VEGF) signalling are activated during sepsis. The objective of this analysis was to investigate the influence of diabetes on biomarkers of endothelial cell activation in sepsis.

METHODS

This was a prospective observational cohort study of a convenience sample of adult patients (age ≥ 18 years) for whom infection was clinically suspected and who presented to an urban tertiary care emergency department between February 2005 and November 2008. We investigated the association of diabetes and sepsis with various endothelial activation biomarkers of cell adhesion (E-selectin, vascular cell adhesion molecule 1 [VCAM-1] and intercellular adhesion molecule 1 [ICAM-1]), coagulation (plasminogen activator inhibitor 1 [PAI-1]) and VEGF signalling (soluble fms-like tyrosine kinase-1 [sFLT-1]).

RESULTS

A total of 207 patients (34% with sepsis, 32% with severe sepsis and 34% with septic shock) were studied, including 63 (30%) with diabetes. Compared with patients without diabetes, patients with diabetes had significantly increased E-selectin and sFLT-1 levels overall; this was most pronounced during septic shock in the stratified analysis. Multivariate models including age, sex, sepsis severity and other variables as potential covariates confirmed the association of diabetes with elevated circulating plasma levels of E-selectin (standardised β 0.24, p < 0.001) and sFLT-1 (standardised β 0.19, p < 0.01), but there was no significant association with VCAM-1, ICAM-1 or PAI-1.

CONCLUSIONS/INTERPRETATION

During septic shock, patients with diabetes had higher levels of circulating biomarkers of endothelial cell adhesion (E-selectin) and VEGF signalling (sFLT-1). Future studies should address whether enhanced activation of the endothelium places patients with diabetes at increased risk for the development of sepsis and worsening morbidity and mortality.

C-reactive protein impairs coronary arteriolar dilation to prostacyclin synthase activation: role of peroxynitrite

Endothelium-derived vasodilators, i.e., nitric oxide (NO), prostacyclin (PGI(2)) and prostaglandin E(2) (PGE(2)), play important roles in maintaining cardiovascular homeostasis. C-reactive protein (CRP), a biomarker of inflammation and cardiovascular disease, has been shown to inhibit NO-mediated vasodilation. The goal of this study was to determine whether CRP also affects endothelial arachidonic acid (AA)-prostanoid pathways for vasomotor regulation. Porcine coronary arterioles were isolated and pressurized for vasomotor study, as well as for molecular and biochemical analysis. AA elicited endothelium-dependent vasodilation and PGI(2) release. PGI(2) synthase (PGI(2)-S) inhibitor trans-2-phenyl cyclopropylamine blocked vasodilation to AA but not to serotonin (endothelium-dependent NO-mediated vasodilator). Intraluminal administration of a pathophysiological level of CRP (7 microg/mL, 60 min) attenuated vasodilations to serotonin and AA but not to nitroprusside, exogenous PGI(2), or hydrogen peroxide (endothelium-dependent PGE(2) activator). CRP also reduced basal NO production, caused tyrosine nitration of endothelial PGI(2)-S, and inhibited AA-stimulated PGI(2) release from arterioles. Peroxynitrite scavenger urate failed to restore serotonin dilation, but preserved AA-stimulated PGI(2) release/dilation and prevented PGI(2)-S nitration. NO synthase inhibitor L-NAME and superoxide scavenger TEMPOL also protected AA-induced vasodilation. Collectively, our results suggest that CRP stimulates superoxide production and the subsequent formation of peroxynitrite from basal released NO compromises PGI(2) synthesis, and thus endothelium-dependent PGI(2)-mediated dilation, by inhibiting PGI(2)-S activity through tyrosine nitration. By impairing PGI(2)-S function, and thus PGI(2) release, CRP could promote endothelial dysfunction and participate in the development of coronary artery disease.

Overexpression of CuZn-SOD Prevents Lipopolysaccharide-Induced Endothelial Dysfunction

Background and Purpose— Inflammation is thought to be a major contributor to carotid artery disease. Lipopolysaccharide (LPS) activates inflammatory mechanisms thought to contribute to endothelial dysfunction by mechanisms that are not well defined. The goal of this study was to determine whether overexpression of CuZn-SOD protects against LPS-induced increases in superoxide and endothelial dysfunction.

Methods— Carotid arteries from CuZn-SOD transgenic (SOD-Tg) and nontransgenic (non-Tg) littermates were examined in vitro. Superoxide levels were measured using lucigenin-enhanced chemiluminescence.

Results— In non-Tg mice, LPS (0.5 μg/mL for 22 hours) produced marked impairment of vasorelaxation in response to the endothelium-dependent dilator acetylcholine (ACh). For example, 100 μmol/L ACh relaxed carotid arteries from non-Tg mice by 86±6% and 38±8% after treatment with vehicle and LPS, respectively. In contrast, LPS did not significantly impair responses of carotid artery to ACh in SOD-Tg mice, and LPS had no effect on relaxation responses to the endothelium-independent dilator nitroprusside in carotid artery from non-Tg or SOD-Tg mice. LPS-induced increases in superoxide, as measured using lucigenin-enhanced chemiluminescence, were higher in vessels from non-Tg mice than from SOD-Tg mice.

Conclusions— These results indicate that LPS increases superoxide and impairs endothelium-dependent relaxation. Overexpression of the CuZn isoform of SOD effectively prevents LPS-induced oxidative stress and endothelial dysfunction in the carotid artery.

Molecular Mechanisms by Which Metabolic Control May Improve Outcomes

OBJECTIVE

To summarize available evidence providing potential explanations for metabolic and nonmetabolic abnormalities during conditions of acute stress and possible mechanisms whereby insulin therapy may affect these changes.

RESULTS

Recent studies have demonstrated a remarkable effect of intensive insulin therapy and reductions in morbidity and mortality in patients in intensive-care units and other hospital settings. The mechanisms involved in these effects are under thorough investigation. Insulin therapy improves glucose and lipid homeostasis, both of which are deleterious to the tissues, especially during severe stress. In addition, insulin has direct effects on the levels of inflammatory cytokines and other proteins that may influence the overall outcome of patients undergoing various stressful conditions.

CONCLUSION

Analysis of published studies suggests that the beneficial effects of insulin therapy may be derived from both direct and indirect mechanisms.