Olmesartan ameliorates insulin sensitivity by modulating tumor necrosis factor-alpha and cyclic AMP in skeletal muscle

Blood-brain barrier dysfunction in ischemic stroke and diabetes: the underlying link, mechanisms and future possible therapeutic targets

Ischemic stroke caused by occlusion of cerebral artery is responsible for the majority of stroke that increases the morbidity and mortality worldwide. Diabetes mellitus (DM) is a crucial risk factor for ischemic stroke. Prolonged DM causes various microvascular and macrovascular changes, and blood-brain barrier (BBB) permeability that facilitates inflammatory response following stroke. In the acute phase following stroke, BBB disruption has been considered the initial step that induces neurological deficit and functional disabilities. Stroke outcomes are significantly worse among DM. In this article, we review stroke with diabetes-induce BBB damage, as well as underlying mechanism and possible therapeutic targets for stroke with diabetes.

Real-world use of ACEI/ARB in diabetic hypertensive patients before the initial diagnosis of obstructive coronary artery disease: patient characteristics and long-term follow-up outcome

Background

Current guidelines recommend angiotensin-converting-enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) as a first-line therapy in diabetic hypertensive patients and for secondary prevention in patients with obstructive coronary artery disease (OCAD). However, the effects of using ACEI/ARB before the initial diagnosis of OCAD on major adverse cardiac and cerebral event (MACCE) in diabetic hypertensive patients remain unclear. This study investigated whether using ACEI/ARB before the initial diagnosis of OCAD could be associated with improved clinical outcomes in diabetic hypertensive patients.

Methods

A total of 2501 patients with hypertension and diabetes, who were first diagnosed with OCAD by coronary angiography, were included in the analysis. Of the 2501 patients, 1300 did not used ACEI/ARB before the initial diagnosis of OCAD [the ACEI/ARB(-) group]; 1201 did [the ACEI/ARB(+) group]. Propensity score matching at 1:1 was performed to select 1050 patients from each group. Incidence of acute myocardial infarction (AMI), infarct size in patients with AMI, heart function, and subsequent MACCE during a median of 25.4-month follow-up were determined and compared between the 2 groups.

Results

Compared with the ACEI/ARB(-) group, the ACEI/ARB(+) group had significantly lower incidence of AMI (22.5% vs. 28.4%, p < 0.05), smaller infarct size in patients with AMI (pTNI: 5.7 vs. 6.8 ng/ml, p < 0.05; pCKMB: 21.7 vs. 28.7 ng/ml, p < 0.05), better heart function (LVEF: 60.0 vs. 58.5%, p < 0.05), and lower incidences of non-fatal stroke (2.4% vs. 4.6%, p < 0.05) and composite MACCE (23.1% vs. 29.7%, p < 0.05). No prior ACEI/ARB therapy was significantly and independently associated with non-fatal stroke and composite MACCE.

Conclusions

In diabetic hypertensive patients, treatment with ACEI/ARB before the initial diagnosis with OCAD was associated with decreased incidence of AMI, smaller infarct size, improved heart function, and lower incidences of non-fatal stroke and composite MACCE.

Trial registration Retrospectively registered

Effects of telmisartan and olmesartan on insulin sensitivity and renal function in spontaneously hypertensive rats fed a high fat diet

Although telmisartan, an angiotensin II receptor blocker (ARB), has an agonistic action for proliferator-activated receptor (PPAR)-γ in vitro, it remains to be determined whether telmisartan exerts such an action in vivo using a non-toxic dose (<5 mg/kg in rats). To address the issue, telmisartan (2 mg/kg) and olmesartan (2 mg/kg), another ARB without PPAR-γ agonistic action, were given to spontaneously hypertensive rats (SHR) fed a high fat diet (HFD). HFD decreased plasma adiponectin, and caused insulin resistance, hypertriglyceridemia and renal damage, which were improved by ARBs. Protective effects of telmisartan and olmesartan did not significantly differ. In addition, in vitro study showed that 1 μM of telmisartan did not elevate the mRNA expression of adipose protein 2, which is a PPAR-γ-stimulated adipogenic marker gene, in preadipocytes with 3% albumin. To obtain 1 μM of plasma concentration, oral dose of telmisartan was calculated to be 6 mg/kg, which indicates that PPAR-γ agonistic action is negligible with a non-toxic dose of telmisartan (<5 mg/kg) in rats. This study showed that 2 mg/kg of telmisartan and olmesartan ameliorated insulin resistance, hypertriglyceridemia and renal damage in SHR fed a HFD. As beneficial effects of telmisartan and olmesartan did not significantly differ, these were mediated through the PPAR-γ-independent actions.

Angiotensin receptor blockers (ARB) outperform angiotensin-converting enzyme (ACE) inhibitors on ischemic stroke prevention in patients with hypertension and diabetes - A real-world population study in Taiwan

BACKGROUND

Combination therapy with angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB) has been stressed for its comprehensive blocking of the renin-angiotensin-aldosterone system, but the evidence for their respective safety and efficacy, in particular with stroke prevention, is still insufficient in population-based follow-up studies in the real world.

METHODS

Using Taiwan's National Health Insurance claims data, we identified 5445 subjects aged 18years and older who had newly diagnosed hypertension in 1997-2010, from them diagnosed type 2 diabetes later. Among them, 2161 patients took ACEI, 1703 patients took ARB, 165 patients took both ACEI and ARB, and 1416 patients had neither.

RESULTS

During the follow-up period, the stroke incidence density was the lowest (23.02 per 1000person-years) in ARB group, followed by the group with neither medication, the ACEI group, and ARB/ACEI combination group (24.06, 30.23, and 37.86 per 1000person-years, respectively). Compared with patients taking neither medication, the adjusted hazard ratios (HRs) were 1.27 (95% CI 1.02-1.58) for ACEI group, 0.95 (95% CI 0.74-1.22) for ARB group, and 1.56 (95% CI 0.99-2.47) for ARB/ACEI combined group. Greater reduction in risk of stroke was observed in patients with high dose ARB (adjusted HR=0·42, 95% CI 0·24-0·75).

CONCLUSION

Our findings support the practice that ARBs could be used, from the perspective of stroke prevention, as a first-line antihypertensive drug for patients with both hypertension and diabetes. The group with ARB regimen reduces 26% of stroke in contrast to the group with ACEI regimen.

Renin-angiotensin system: an old player with novel functions in skeletal muscle

Skeletal muscle is a tissue that shows the most plasticity in the body; it can change in response to physiological and pathological stimuli. Among the diseases that affect skeletal muscle are myopathy-associated fibrosis, insulin resistance, and muscle atrophy. A common factor in these pathologies is the participation of the renin-angiotensin system (RAS). This system can be functionally separated into the classical and nonclassical RAS axis. The main components of the classical RAS pathway are angiotensin-converting enzyme (ACE), angiotensin II (Ang-II), and Ang-II receptors (AT receptors), whereas the nonclassical axis is composed of ACE2, angiotensin 1-7 [Ang (1-7)], and the Mas receptor. Hyperactivity of the classical axis in skeletal muscle has been associated with insulin resistance, atrophy, and fibrosis. In contrast, current evidence supports the action of the nonclassical RAS as a counter-regulator axis of the classical RAS pathway in skeletal muscle. In this review, we describe the mechanisms involved in the pathological effects of the classical RAS, advances in the use of pharmacological molecules to inhibit this axis, and the beneficial effects of stimulation of the nonclassical RAS pathway on insulin resistance, atrophy, and fibrosis in skeletal muscle.

Relationship between achieved blood pressure, dietary habits and cardiovascular disease in hypertensive patients treated with olmesartan: the OMEGA study

We investigated the relationship between cardiovascular disease (CVD) and the achieved blood pressure, dietary habits and the presence/absence of metabolic syndrome (MetS) in hypertensive patients treated with olmesartan medoxomil. A prospective cohort study with a 3-year follow-up was conducted in 14 721 olmesartan-naive outpatients (mean age: 64.9 years, 49.6% women) with essential hypertension. The association of CVD with achieved blood pressure, dietary habits and MetS was investigated by Cox proportional hazards analysis. There were 3059 patients (31.8%) with MetS (Japanese criteria) among 9625 evaluable patients. The mean baseline blood pressure was 157.4/88.8 mm Hg, which decreased to 134.0/76.1 mm Hg during treatment (P<0.0001). The annual incidence of CVD was 7.15 per 1000 persons during the study period. When the achieved blood pressure was stratified according to the Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2009), the risk of CVD increased significantly along with the severity of hypertension (P<0.0001), especially the risk of stroke. Investigation of dietary habits revealed a significant association between salt intake and the risk of stroke. Higher salt intake was associated with a significantly higher risk of stroke than lower salt intake (hazard ratio, 1.897; 95% confidence interval, 1.003–3.590). Blood pressure was well controlled in both patients with and without MetS, and there was no significant difference in the incidence of events between the two groups. In conclusion, the severity of hypertension (achieved blood pressure) is associated with the incidence of CVD, and the results of this study suggest that tight blood pressure control and salt restriction are important for preventing stroke.

Angiotensin II receptor activation in youth triggers persistent insulin resistance and hypertension--a legacy effect?

Although the involvement of angiotensin II (Ang II) in insulin resistance and hypertension has been established, the temporal relationships between Ang II receptor activation and changes in insulin sensitivity and blood pressure are not clear. To better understand this issue, we infused rats with Ang II (200 ng kg(-1) min(-1)) or vehicle for 4 weeks and assessed the residual effects after the discontinuation of the infusion on blood pressure, insulin sensitivity and tissue parameters of inflammation. Four weeks after the discontinuation of the Ang II infusion, the blood pressure was higher by 12.8 mm Hg, and insulin sensitivity as determined by a euglycemic hyperinsulinemic glucose clamp was reduced (glucose infusion rate: 11.1±0.7 vs. 17.6±0.5 mg kg(-1) min(-1)) in the Ang II-treated group compared with controls. The persistent hypertension and insulin resistance were associated with greater than two-fold increases in macrophage chemoattractant protein-1, tumor necrosis factor-α and thiobarbituric acid-reactive substrates in the soleus muscle. Furthermore, total and activated forms of Rac-1, a regulatory subunit of the NADPH oxidase complex, were increased by 144±14% and 277±82%, respectively, in the skeletal muscle of Ang II-treated rats. These residual effects after Ang II infusion were all attenuated by the co-administration of tempol, a free radical scavenger, or candesartan with Ang II. The effects of candesartan were not mimicked by hydralazine at an equidepressant dose. These findings suggest that Ang II receptor activation in youth triggers the upregulation of inflammatory cytokines and the production of reactive oxygen species, thereby inducing later insulin resistance and hypertension.

Inflammatory effects of nutritional stimuli: further support for the need for a big picture approach to tackling obesity and chronic disease

The discovery of a form of low-grade systemic inflammation (called 'metaflammation'), and the close evolutionary link between the immune and metabolic systems, poses questions about the supposed antigens (inducers) of such an immune reaction. Initially, this was thought to be mediated through obesity. However, we have identified a number of lifestyle or environmentally related inducers that may cause metaflammation, even in the absence of obesity. In this paper, the third of a series linking obesity with broad environmental and evolutionary factors, we identify nutritional stimuli with evidence of an involvement in metaflammation. From this we propose that components of certain foods and beverages with which humans have not evolved, are more often the inducers of an inflammatory effect in the body than those with which humans have become more familiar, and to which a neutral, or anti-inflammatory response may be expected to have developed. The implications of such a finding are considered in relation to broader aspects of the environment, economic growth, policy change and current global financial issues.

Effects of a high-salt diet on adipocyte glucocorticoid receptor and 11-beta hydroxysteroid dehydrogenase 1 in salt-sensitive hypertensive rats

High-salt diets decrease insulin sensitivity in salt-sensitive hypertensive rats, and glucocorticoids promote adipocyte growth and may have pathophysiological roles in the metabolic syndrome. The aim of this study was to clarify the relationship between high-salt diet and the adipocyte glucocorticoid hormones in salt-sensitive hypertensive rats. Six-week-old Dahl salt-sensitive (DS) hypertensive rats and salt-resistant (DR) rats were fed a high-salt diet or a normal-salt diet for 4 weeks. Fasting blood glucose (FBG), serum adiponectin, plasma insulin, and corticosterone in plasma and in visceral adipose tissues, 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1) activities in adipose tissues and glucose uptake in isolated muscle were measured. Animals underwent an oral glucose tolerance test (OGTT). The expression of mRNA for glucocorticoid receptor (GR), 11beta-HSD1 and tumor necrosis factor-alpha (TNF-alpha) in adipose tissues were measured using a real-time PCR. A high-salt diet did not influence FBG; however, decreased 2-deoxy glucose uptake and plasma insulin during OGTT in DS rats. The high-salt diet increased significantly adipose tissue corticosterone concentration and 11beta-HSD1 activities, gene expression for GR, 11beta-HSD1 and TNF-alpha in adipose tissues in DS rats compared with DR rats (p<0.05). The high-salt diet did not influence plasma corticosterone and serum adiponectin concentration in DS and DR rats. These results suggest that changes in GR and 11beta-HSD1 in adipose tissue may contribute to insulin sensitivity in salt-sensitive hypertensive rats.

Effects of enalapril or nifedipine on muscle strength or functional capacity in elderly subjects. A double blind trial

INTRODUCTION

The inhibition of angiotensin-converting enzyme could be useful to avoid sarcopenia in the elderly.

MATERIALS AND METHODS

We compared in a prospective double blind trial, the effects of treatment with enalapril or nifedipine on muscle performance in hypertensive elderly subjects. Patients were followed for nine months, and at baseline, 4.5 months and the end of follow-up, quadriceps and hand grip muscle strength, walking capacity, timed up and go and the short physical performance test were measured.

RESULTS

During follow-up, more subjects on nifedipine than on enalapril discontinued the medication due to side-effects. No differences in the evolution of muscle strength, walking capacity or functional measures were observed. At nine months, plasma angiotensin-converting enzyme activity decreased by 6.0+/-2.5 U/L among patients on enalapril and increased by 8.5+/-4.2 U/L (p<0.001) among patients on nifedipine.

CONCLUSION

In this group of elderly subjects, enalapril was not superior to nifedipine with regard to the age-related decline of muscle performance.

Effect of valsartan addition to amlodipine on insulin sensitivity in overweight-obese hypertensive patients

OBJECTIVE

The aim of the study was to evaluate the effect of valsartan/amlodipine combination on insulin sensitivity in overweight-obese hypertensive patients.

METHODS

After a 4-week placebo period, 58 overweight-obese (BMI >or=25 kg/m(2)) patients, with mild to moderate essential hypertension (DBP >95 and <110 mmHg, SBP >140 mmHg) were treated with amlodipine 5 mg od or valsartan 160 mg od or amlodipine 5 mg plus valsartan 160 mg od for 8 weeks according to a randomized, open-label, blinded end-point, cross-over study. At the end of the placebo period and each treatment period, blood pressure (BP) and insulin sensitivity (IS) (by euglycemic hyperinsulinemic clamp technique) were evaluated. IS was expressed as the amount of glucose infused during the last 30 min (glucose infusion rate, GIR) in mg/kg/min.

RESULTS

Valsartan/amlodipine combination produced a significantly greater decrease in SBP/DBP values (-22.3/16.7 mmHg, p<0.001 vs baseline) than valsartan (-15.2/11.7 mmHg, p<0.01 vs baseline) and amlodipine monotherapy (-16.1/12.6 mmHg, p<0.01 vs baseline). Both valsartan and amlodipine provided a significant increase in GIR (+1.24 mg/kg/min, p=0.036 vs baseline and +1.02 mg/kg/min, p=0.047, respectively), but such an increase was significantly greater with their combination (+1.82 mg/kg/min, p<0.01 vs baseline). These greater changes in IS were not related to BP changes.

CONCLUSION

Valsartan/amlodipine combination improved IS more than respective monotherapy beyond affording greater BP reductions. This strengthens the rationale to use valsartan/amlodipine combination in the treatment of overweight-obese hypertensives.

Skeletal muscle insulin resistance: role of inflammatory cytokines and reactive oxygen species

The cardiometabolic syndrome (CMS), with its increased risk for cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD), and chronic kidney disease (CKD), has become a growing worldwide health problem. Insulin resistance is a key factor for the development of the CMS and is strongly related to obesity, hyperlipidemia, hypertension, type 2 diabetes mellitus (T2DM), CKD, and NAFLD. Insulin resistance in skeletal muscle is particularly important since it is normally responsible for more than 75% of all insulin-mediated glucose disposal. However, the molecular mechanisms responsible for skeletal muscle insulin resistance remain poorly defined. Accumulating evidence indicates that low-grade chronic inflammation and oxidative stress play fundamental roles in the development of insulin resistance, and inflammatory cytokines likely contribute to the link between inflammation, oxidative stress, and skeletal muscle insulin resistance. Understanding the mechanisms by which skeletal muscle tissue develops resistance to insulin will provide attractive targets for interventions, which may ultimately curb this serious problem. This review is focused on the effects of inflammatory cytokines and oxidative stress on insulin signaling in skeletal muscle and consequent development of insulin resistance.

Green tea increases anti-inflammatory tristetraprolin and decreases pro-inflammatory tumor necrosis factor mRNA levels in rats

Background

Tristetraprolin (TTP/ZFP36) family proteins have anti-inflammatory activity by binding to and destabilizing pro-inflammatory mRNAs such as Tnf mRNA, and represent a potential therapeutic target for inflammation-related diseases. Tea has anti-inflammatory properties but the molecular mechanisms have not been completely elucidated. We hypothesized that TTP and/or its homologues might contribute to the beneficial effects of tea as an anti-inflammatory product.

Methods

Quantitative real-time PCR was used to investigate the effects of green tea (0, 1, and 2 g solid extract/kg diet) on the expression of Ttp family genes (Ttp/Tis11/Zfp36, Zfp36l1/Tis11b, Zfp36l2/Tis11d, Zfp36l3), pro-inflammatory genes (Tnf, Csf2/Gm-csf, Ptgs2/Cox2), and Elavl1/Hua/Hur and Vegf genes in liver and muscle of rats fed a high-fructose diet known to induce insulin resistance, oxidative stress, inflammation, and TNF-alpha levels.

Results

Ttp and Zfp36l1 mRNAs were the major forms in both liver and skeletal muscle. Ttp, Zfp36l1, and Zfp36l2 mRNA levels were more abundant in the liver than those in the muscle. Csf2/Gm-csf and Zfp36l3 mRNAs were undetectable in both tissues. Tea (1 g solid extract/kg diet) increased Ttp mRNA levels by 50–140% but Tnf mRNA levels decreased by 30% in both tissues, and Ptgs2/Cox2 mRNA levels decreased by 40% in the muscle. Tea (2 g solid extract/kg diet) increased Elavl1/Hua/Hur mRNA levels by 40% in the liver but did not affect any of the other mRNA levels in liver or muscle.

Conclusion

These results show that tea can modulate Ttp mRNA levels in animals and suggest that a post-transcriptional mechanism through TTP could partially account for tea's anti-inflammatory properties. The results also suggest that drinking adequate amounts of green tea may play a role in the prevention of inflammation-related diseases.

Effect of Olmesartan on Oxidative Stress in Hemodialysis Patients

The effect of olmesartan, an inverse angiotensin II type 1 receptor blocker (ARB), on oxidative stress in hemodialysis (HD) patients is not fully understood, and has not been widely investigated in vitro or in vivo. We determined the amount of oxidized albumin and albumin hydroperoxides formed during incubation in the absence and presence of olmesartan by high-performance liquid chromatography (HPLC) and by a ferrous oxidation xylenol assay in an in vitro study. Six hypertensive HD patients were treated with 40 mg of olmesartan once daily, and blood pressure monitoring (BPM) was performed after 0, 4, and 8 weeks of treatment. The ratio of oxidized to unoxidized albumin was also determined. The oxidized albumin ratios and levels of albumin hydroperoxides were significantly decreased in a concentration-dependent manner in the presence of olmesartan, compared with the absence of olmesartan (p<0.05) in in vitro studies. In HD patients, olmesartan also significantly reduced systolic and diastolic blood pressure after 4 weeks, with a further significant decrease after 8 weeks. The ratio of oxidized to unoxidized albumin was markedly decreased after 4 weeks and these lower levels were maintained at 8 weeks. Olmesartan effectively lowered the extent of oxidation of albumin in both in vitro and in vivo studies, and this effect might confer benefits beyond a reduction in blood pressure.