Pioglitazone lowers blood pressure in hypertensive patients with type 2 diabetes mellitus : an open, multicentre, observational study

SGLT2 Inhibitors and Cardiovascular Risk: Lessons Learned From the EMPA-REG OUTCOME Study

Although cardiovascular (CV) mortality is the principal cause of death in individuals with type 2 diabetes (T2DM), reduction of plasma glucose concentration has little effect on CV disease (CVD) risk. Thus, novel strategies to reduce CVD risk in T2DM patients are needed. The recently published BI 10773 (Empagliflozin) Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients (EMPA-REG OUTCOME) study demonstrated that in T2DM patients with high CVD risk empagliflozin reduced the primary major adverse cardiac event end point (CV death, nonfatal myocardial infarction, nonfatal stroke) by 14%. This beneficial effect was driven by a 38% reduction in CV mortality with no significant decrease in nonfatal myocardial infarction or stroke. Empagliflozin also caused a 35% reduction in hospitalization for heart failure without affecting hospitalization for unstable angina. Although sodium-glucose cotransporter 2 inhibitors exert multiple metabolic benefits (decreases in HbA1c, body weight, and blood pressure and an increase in HDL cholesterol), all of which could reduce CVD risk, it is unlikely that the reduction in CV mortality can be explained by empagliflozin's metabolic effects. More likely, hemodynamic effects, specifically reduced blood pressure and decreased extracellular volume, are responsible for the reduction in CV mortality and heart failure hospitalization. In this Perspective, we will discuss possible mechanisms for these beneficial effects of empagliflozin and their implications for the care of T2DM patients.

Pioglitazone enhances the blood pressure-lowering effect of losartan via synergistic attenuation of angiotensin II-induced vasoconstriction

INTRODUCTION

This study was designed to investigate the underlying mechanisms of synergistic antihypertensive effect produced by combination therapy of losartan and pioglitazone in metabolic syndrome (MS) rats.

MATERIALS AND METHODS

An MS model was induced by feeding rats a high-fat, high-sodium diet and 20% sucrose solution. Losartan (20 mg/kg/day), pioglitazone (10 mg/kg/day), and their combination were orally administered for eight consecutive weeks. Systolic blood pressure (SBP) and mean arterial pressure (MAP) were measured using the tail-cuff method and carotid arterial catheterization, respectively. The aortas were isolated and in vitro vascular reactivity studies were performed. The protein expression of angiotensin type 1 receptor (AT1), endothelial nitric oxide synthase (eNOS), phosphorylated eNOS and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit p47(phox), level of nitrotyrosine as well as activity of eNOS and NADPH oxidase in aortas of MS rats were detected.

RESULTS

After eight weeks of treatment, the SBP and MAP in the losartan (115 ± 5 and 106 ± 6 mmHg), pioglitazone (130 ± 6 and 118 ± 6 mmHg), and combination therapy (105 ± 6 and 98 ± 5 mmHg) groups were lower than those in the model group (150 ± 8 and 136 ± 9 mmHg). Combination therapy of losartan and pioglitazone reduced BP more than either monotherapy, and showed additive effects on improving endothelial dysfunction and abolishing the increased vascular responsiveness to angiotensin II. These synergistic effects were associated with further reductions in protein expression of p47(phox) and AT1, NADPH oxidase activity, and nitrotyrosine level.

CONCLUSIONS

Our data indicate that combined treatment exerts more beneficial effects on lowering BP and improving vascular lesions.

Understanding the genetic basis for adverse drug effects: the calcineurin inhibitors

The calcineurin inhibitors-cyclosporine and tacrolimus-are the mainstay of immunosuppressive therapy in solid organ transplantation. These drugs produce severe adverse drug effects (ADEs) such as nephrotoxicity, posttransplantation diabetes mellitus, and hypertension. Accumulated evidence suggests that the development of type 2 diabetes, hypertension, and renal failure may be associated with specific DNA genotypes. In this review, the genes involved with the development of these disease processes are compared with those implicated in calcineurin inhibitor-induced ADEs. The renin-angiotensin system genes, cytokine-encoding genes, and plasminogen activator inhibitor type 1 genes have been implicated in calcineurin inhibitor-induced nephrotoxicity, as well as in development of renal failure. A number of genes are implicated in contributing to diabetes, and these include the vitamin D receptor gene, VDR; hepatocyte nuclear factor genes, HNF; transcription factor 7-like 2 gene, TCF7L2; angiotensin-converting enzyme gene, ACE; cytokines; peroxisome proliferator-activated receptor gamma gene, PPARG; and others. Studies have suggested that the VDR, PPARG, HNF1A, and adenosine 5'-triphosphate-binding cassette ABCC8 (which encodes the sulfonylurea receptor) genes are associated with calcineurin inhibitor-induced diabetes. The genes encoding for the angiotensin-converting enzyme, endothelial constitutive nitric oxide synthase, and cytochrome P450 3A isoenzyme have been involved in the development of hypertension and in calcineurin inhibitor-induced hypertension. The genetic study of disease states can be the stepping stones for thoroughly understanding the genetic basis of ADEs. Gene polymorphisms are implicated in the development of diseases and corresponding disease-like ADEs. The disease-associated genes provide candidate genes for exploring ADEs and may provide genomic biomarkers for assessing the risk for developing severe calcineurin inhibitor-related ADEs as well as for developing preventive strategies.

Pioglitazone inhibits Toll-like receptor expression and activity in human monocytes and db/db mice

Toll-like receptors (TLRs) are key innate immune sensors of endogenous damage signals and play an important role in inflammatory diseases like diabetes and atherosclerosis. Pioglitazone (PIO), a peroxisome proliferator-activated receptor (PPAR)-gamma agonist, has been reported to be an antiinflammatory agent. Thus, in the present study, we examined the antiinflammatory effects of PIO on TLR2 and TLR4 expression in human monocytes exposed to Pam3CSK4 (Pam; TLR2 ligand) and purified lipopolysaccharide (LPS; TLR4 ligand) using flow cytometry and real-time RT-PCR. Monocytes were isolated from healthy human volunteers and pretreated with PIO (1 microM) followed by Pam (170 ng/ml) and LPS (160 ng/ml) challenge. PIO significantly decreased Pam- and LPS-induced TLR2 (-56%) and TLR4 (-78%) expression (P < 0.05). In addition, PIO decreased TLR ligand-induced nuclear factor-kappaB activity (-63%), IL-1beta (-50%), IL-6 (-52%), monocyte chemoattractant protein-1(-83%), and TNF-alpha (-87%) compared with control. Next, PIO-treated db/db mice (n = 6/group) showed decreased TLR2 (-60%) and TLR4 (-45%) expression in peritoneal macrophages compared with vehicle control mice (P < 0.001) with associated decrease in MyD88-dependent signaling and nuclear factor-kappaB activation. Data suggest that Pam- and LPS-induced TLR2 and TLR4 expression are inhibited by PIO in human monocytes and db/db mice. Thus, we define a novel pathway by which PIO could induce antiinflammatory effects.

Association between the Pro12Ala variant of the peroxisome proliferator-activated receptor-gamma2 gene and increased 24-h diastolic blood pressure in obese patients with type II diabetes

The aim of the study was to examine an association between the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR)-gamma2 gene and blood pressure values assessed by 24-h ambulatory blood pressure monitoring (ABPM) in obese patients with long-lasting type II diabetes. Two hundred and fourteen obese patients (95 men and 119 women) with above 10-year history of type II diabetes were recruited for the study. In all the patients, ABPM was performed and other parameters, including age, body mass index (BMI), waist/hip ratio (WHR), haemoglobin A1c (HbA(1c)), serum lipids and creatinine were also evaluated. The Pro12Ala polymorphism was analysed by polymerase chain reaction-restriction fragment length polymorphism. Two subgroups of patients were compared: (a) Pro/Pro: homozygotic Pro/Pro (n=154) and (b) Ala: Ala allele carriers (Ala/Ala+Ala/Pro) (n=60). The studied groups were not different when age, BMI, WHR, HbA(1c), lipids, creatinine and frequency of hypertension were compared. A similar ratio of patients from both groups were treated with angiotensin-converting enzyme inhibitors, calcium channel blockers, diuretics, beta-blockers and alpha-blockers. A difference was observed in a mean 24-h (Ala: 71.9+/-8.1 vs Pro/Pro: 69.4+/-7.8 mm Hg, P=0.034) and a mean night time (Ala: 67.1+/-7.8 vs Pro/Pro: 64.5+/-8.4 mm Hg, P=0.025) diastolic blood pressure, which was significantly higher in patients with Ala variant. There was also a trend towards a higher mean daytime diastolic blood pressure in this group. It seems that the Pro12Ala variant is associated with an increased mean 24-h diastolic blood pressure in obese diabetic patients. Different reaction for antihypertensive medication depending on a variant of the PPAR-gamma2 gene should also be considered as a possible cause of the presented results.