This study aimed to investigate the causal role of diabetes mellitus (DM), glycemic traits, and sodium-glucose cotransporter 2 (SGLT2) inhibition in pulmonary arterial hypertension (PAH). Utilizing a two-sample two-step Mendelian randomization (MR) approach, we determined the causal influence of DM and glycemic traits (including insulin resistance, glycated hemoglobin, and fasting insulin and glucose) on the risk of PAH. Moreover, we examined the causal effects of SGLT2 inhibition on the risk of PAH. Genetic proxies for SGLT2 inhibition were identified as variants in the SLC5A2 gene that were associated with both levels of gene expression and hemoglobin A1c. Results showed that genetically inferred DM demonstrated a causal correlation with an increased risk of PAH, exhibiting an odds ratio (OR) of 1.432, with a 95% confidence interval (CI) of 1.040-1.973, and a p-value of 0.028. The multivariate MR analysis revealed comparable outcomes after potential confounders (OR = 1.469, 95%CI = 1.021-2.115, p = 0.038). Moreover, genetically predicted SGLT2 inhibition was causally linked to a reduced risk of PAH (OR = 1.681*10-7, 95%CI = 7.059*10-12-0.004, p = 0.002). Therefore, our study identified the suggestively causal effect of DM on the risk of PAH, and SGLT2 inhibition may be a potential therapeutic target in patients with PAH.

Endothelin-1 (ET-1) is elevated in patients with systemic lupus erythematosus (SLE), an autoimmune disease characterized by high rates of hypertension, renal injury, and cardiovascular disease. SLE is also associated with an increased prevalence of obesity and insulin resistance compared to the general population. In the present study, we tested the hypothesis that elevated ET-1 in SLE contributes to obesity and insulin resistance. For these studies, we used the NZBWF1 mouse model of SLE, which develops obesity and insulin resistance on a normal chow diet. To test this hypothesis, we treated control (NZW) and SLE (NZBWF1) mice with vehicle, atrasentan (ETA receptor antagonist, 10 mg/kg/day), or bosentan (ETA/ETB receptor antagonist, 100 mg/kg/day) for 4 wk. Neither treatment impacted circulating immunoglobulin levels, but treatment with bosentan lowered anti-dsDNA IgG levels, a marker of SLE disease activity. Treatment with atrasentan and bosentan decreased glomerulosclerosis, and atrasentan lowered renal T-cell infiltration. Body weight was lower in SLE mice treated with atrasentan or bosentan. Endothelin receptor antagonism also improved hyperinsulinemia, homeostatic model assessment for insulin resistance, and glucose tolerance in SLE mice. Adipose tissue inflammation was also improved by endothelin receptor blockade. Taken together, these data suggest a potential therapeutic benefit for SLE patients with obesity and insulin resistance.NEW & NOTEWORTHY SLE is an autoimmune disease that is associated with obesity, insulin resistance, and elevated endothelin-1. The present study demonstrated that pharmacological inhibition of endothelin receptors decreased body weight, insulin resistance, and adipose tissue inflammation in a murine model of SLE. The therapeutic potential of endothelin receptor antagonists to treat obesity-related diseases and pathophysiological conditions, such as autoimmune diseases and insulin resistance, has become increasingly clear.

Diabetic nephropathy (DN) is the main cause of chronic kidney disease and end-stage renal disease worldwide. Although available clinical trials have shown that endothelin receptor (ER) antagonists may be a novel and beneficial drug for DN, no consistent conclusions regarding their sufficient effectiveness and safety for patients with DN have been presented.

To assess the effectiveness and safety of ER antagonists among patients with DN.

The EMBASE, PubMed, MEDLINE, Cochrane, and ClinicalTrials.gov databases were searched without any language restrictions. Relative risks with 95% confidence intervals (CIs) for dichotomous data and mean differences or standardized mean difference with 95%CIs for continuous data were calculated using Review Manager 5.3 software. Publication bias was assessed using Egger's test with Stata/SE software.

We enrolled seven studies with six data sets and 5271 participants. The ER antagonists group showed a significantly greater reduction in albuminuria and more patients with 40% reduction in urinary albumin-to-creatinine ratio than the control group (P < 0.0001 and P = 0.02, respectively). Subgroup analysis for reductions in estimated glomerular filtration rate (eGFR) showed that for the middle-dosage subgroup, the ER antagonists group exhibited lower eGFR reduction than the control group (P < 0.00001; mean difference, 0.70 95%CI: 0.66, 0.74). Moreover, significant reductions in systolic and diastolic blood pressure were observed in the invention group.

ER blockades combined with angiotensin converting enzyme inhibitor /angiotensin II type 1 receptor blockers may be an effective treatment to lower blood pressure and reduce proteinuria in DN with declined eGFR. However, attention should be given to adverse events, including cardiac failure, anemia, and hypoglycemia, as well as serious adverse events.

Obstructive sleep apnea (OSA) is associated with insulin resistance (IR) and glucose intolerance. Elevated endothelin-1 (ET-1) levels have been observed in OSA patients and in mice exposed to intermittent hypoxia (IH). We examined whether pharmacological blockade of type A and type B ET-1 receptors (ETA and ETB) would ameliorate glucose intolerance and IR in mice exposed to IH. Subcutaneously implanted pumps delivered BQ-123 (ETA antagonist; 200 nmol/kg/day), BQ-788 (ETB antagonist; 200 nmol/kg/day) or vehicle (saline or propyleneglycol [PG]) for 14 days in C57BL6/J mice (10/group). During treatment, mice were exposed to IH (decreasing the FiO2 from 20.9% to 6%, 60/h) or intermittent air (IA). After IH or IA exposure, insulin (0.5 IU/kg) or glucose (1 mg/kg) was injected intraperitoneally and plasma glucose determined after injection and area under glucose curve (AUC) was calculated. Fourteen-day IH increased fasting glucose levels (122 ± 7 vs. 157 ± 8 mg/dL, PG: 118 ± 6 vs. 139 ± 8; both p < 0.05) and impaired glucose tolerance (AUCglucose: 19,249 ± 1105 vs. 29,124 ± 1444, PG AUCglucose: 18,066 ± 947 vs. 25,135 ± 797; both p < 0.05) in vehicle-treated animals. IH-induced impairments in glucose tolerance were partially ameliorated with BQ-788 treatment (AUCglucose: 21,969 ± 662; p < 0.05). Fourteen-day IH also induced IR (AUCglucose: 7185 ± 401 vs. 8699 ± 401; p < 0.05). Treatment with BQ-788 decreased IR under IA (AUCglucose: 5281 ± 401, p < 0.05) and reduced worsening of IR with IH (AUCglucose: 7302 ± 401, p < 0.05). There was no effect of BQ-123 on IH-induced impairments in glucose tolerance or IR. Our results suggest that ET-1 plays a role in IH-induced impairments in glucose homeostasis.

Diabetes with vascular complication needs strict interventions to retard possible serious complications. This research estimated the possible interaction of rosiglitazone (RGN) with losartan (Los) in diabetic rats. Male Sprague-Dawley rats were randomly divided into nondiabetic rats, diabetic rats, and diabetic rats that received RGN, Los, or a combination of RGN and Los. Measurement of serum glucose, vascular adhesion molecule-1, interleukin-6, tumor necrosis factor-α, aortic lipid peroxide (malondialdehyde), glutathione, superoxide dismutase, and total nitrate/nitrite levels was done. Also, the effects of RGN on the relaxation created by acetylcholine and sodium nitroprusside, contraction of isolated aortic rings provoked by phenylephrine and angiotensin II were determined. Results revealed that RGN or Los had a vasodilating effect to variable degrees indicated by enhanced effects on both acetylcholine-induced relaxation and the antagonistic effect on angiotensin II and phenylephrine-stimulated contraction of diabetic aortas with significant amelioration in serum glucose, vascular adhesion molecule-1, interleukin-6, and tumor necrosis factor-α levels and aortic oxidant/antioxidant balance. Treatment of diabetic rats with a combination of RGN and Los produced a more pronounced effect on the measured parameters compared to the diabetic, RGN-, and Los-treated groups. These findings point out the beneficial effects of RGN and Los combination in diabetic rats.

Insulin resistance has emerged as a potential mechanism related to the pathogenesis of idiopathic pulmonary arterial hypertension (IPAH). However, direct measurements of insulin and glucose metabolism have not been performed in patients with IPAH to date.

To perform comprehensive metabolic phenotyping of humans with IPAH.

We assessed plasma insulin and glucose, using an oral glucose tolerance test and estimated insulin resistance, and β-cell function in 14 patients with IPAH and 14 control subjects matched for age, sex, blood pressure, and body mass index. Body composition (dual-energy X-ray absorptiometry), inflammation (CXC chemokine ligand 10, endothelin-1), physical fitness (6-min walk test), and energy expenditure (indirect calorimetry) were also assessed.

Patients with IPAH had a higher rate of impaired glucose tolerance (57 vs. 14%; P < 0.05) and reduced glucose-stimulated insulin secretion compared with matched control subjects (IPAH: 1.31 ± 0.76 μU/ml⋅mg/dl vs. control subjects: 2.21 ± 1.27 μU/ml⋅mg/dl; P < 0.05). Pancreatic β-cell function was associated with circulating endothelin-1 (r = -0.71, P < 0.01) and CXC chemokine ligand 10 (r = -0.56, P < 0.05). Resting energy expenditure was elevated in IPAH (IPAH: 32 ± 3.4 vs. control subjects: 28.8 ± 2.9 kcal/d/kg fat-free mass; P < 0.05) and correlated with the plasma glucose response (r = 0.51, P < 0.01). Greater insulin resistance was associated with reduced 6-minute walk distance (r = 0.55, P < 0.05).

Independent of age, sex, blood pressure, and body mass index, patients with IPAH have glucose intolerance, decreased insulin secretion in response to glucose, and elevated resting energy expenditure. These abnormalities are associated with circulating markers of inflammation and vascular dysfunction.

Long-term repeated-dose toxicity is mainly assessed in animals despite poor concordance of animal data with human toxicity. Nowadays advanced human in vitro systems, eg, metabolically competent HepaRG cells, are used for toxicity screening. Extrapolation of in vitro toxicity to in vivo effects is possible by reverse dosimetry using pharmacokinetic modeling. We assessed long-term repeated-dose toxicity of bosentan and valproic acid (VPA) in HepaRG cells under serum-free conditions. Upon 28-day exposure, the EC50 values for bosentan and VPA decreased by 21- and 33-fold, respectively. Using EC(10) as lowest threshold of toxicity in vitro, we estimated the oral equivalent doses for both test compounds using a simplified pharmacokinetic model for the extrapolation of in vitro toxicity to in vivo effect. The model predicts that bosentan is safe at the considered dose under the assumed conditions upon 4 weeks exposure. For VPA, hepatotoxicity is predicted for 4% and 47% of the virtual population at the maximum recommended daily dose after 3 and 4 weeks of exposure, respectively. We also investigated the changes in the central carbon metabolism of HepaRG cells exposed to orally bioavailable concentrations of both drugs. These concentrations are below the 28-day EC(10) and induce significant changes especially in glucose metabolism and urea production. These metabolic changes may have a pronounced impact in susceptible patients such as those with compromised liver function and urea cycle deficiency leading to idiosyncratic toxicity. We show that the combination of modeling based on in vitro repeated-dose data and metabolic changes allows the prediction of human relevant in vivo toxicity with mechanistic insights.

Although obesity, dyslipidemia and insulin resistance (IR) are well known risk factors for systemic cardiovascular disease, their impact on pulmonary arterial hypertension (PAH) is unknown. The present authors' previous studies indicate that IR may be a risk factor for PAH. The current study has investigated the prevalence of IR in PAH and explored its relationship with disease severity. Clinical data and fasting blood samples were evaluated in 81 nondiabetic PAH females. In total, 967 National Health and Nutrition Examination Surveys (NHANES) females served as controls. The fasting triglyceride to high-density lipoprotein cholesterol ratio was used as a surrogate of insulin sensitivity. While body mass index was similar in NHANES versus PAH females (28.6 versus 28.7 kg.m(-2)), PAH females were more likely to have IR (45.7 versus 21.5%) and less likely to be insulin sensitive (IS; 43.2 versus 57.8%). PAH females mostly (82.7%) had New York Heart Association (NYHA) class II and III symptoms. Aetiology, NYHA class, 6-min walk-distance and haemodynamics did not differ between IR and IS PAH groups. However, the presence of IR and a higher NYHA class was associated with poorer 6-months event-free survival (58 versus 79%). Insulin resistance appears to be more common in pulmonary arterial hypertension females than in the general population, and may be a novel risk factor or disease modifier that might impact on survival.

Since its identification as an endothelial cell-derived vasoconstrictor peptide in 1988, endothelin-1, the predominant member of the endothelin peptide family, has received considerable interest in basic medical science and in clinical medicine, which is reflected by more than 20 000 scientific publications on endothelin research in the past 20 years. The story of endothelin is unique as the gene sequences of endothelin receptors and the first receptor antagonists became available within only 4 years of the identification of the peptide sequence. The first clinical study in patients with congestive heart failure was published only 3 years thereafter. Yet, despite convincing experimental evidence of a pathogenetic role for endothelin in development, cell function, and disease, many initial clinical studies on endothelin antagonism were negative. In many of these studies, study designs or patient selection were inadequate. Today, for diseases such as pulmonary hypertension, endothelin antagonist treatment has become reality in clinical medicine, and ongoing clinical studies are evaluating additional indications, such as renal disease and cancer. Twenty years after the discovery of endothelin, its inhibitors have finally arrived in the clinical arena and are now providing us with new options to treat disease and prolong the lives of patients. Possible future indications include resistant arterial hypertension, proteinuric renal disease, cancer, and connective tissue diseases.

Endothelin plays an important role in the pathogenesis of atherosclerosis. The aim of the study was to evaluate the safety and hemodynamic and metabolic responses to 6 months treatment with atrasentan, the selective endothelin-A receptor antagonist. Seventy-two patients with multiple cardiovascular risk factors and nonobstructive coronary artery disease on coronary angiogram were randomly assigned in a double-blind manner to atrasentan or placebo. Mean aortic blood pressure decreased from 92+/-10 to 80+/-10 mm Hg (P<0.001) in the atrasentan group and did not change in the placebo group (93+/-10 and 92+/-11 mm Hg; P=0.84). The difference between the groups was significant (P<0.001). No effect on heart rate was observed. In a subgroup of patients not treated with angiotensin-converting enzyme inhibitor, creatinine level decreased in the atrasentan versus the placebo group (P=0.011). Fasting glucose (P=0.026), glycosylated hemoglobin level (P=0.041), triglyceride l (P=0.013), lipoprotein-A (P=0.046), and uric acid levels (P=0.048) decreased significantly in the atrasentan group compared with the placebo group. No progression of angiographic coronary disease was observed. The most common adverse effects with atrasentan were nasal stuffiness, headache, and edema. In conclusion, 6 months of treatment with atrasentan results in a reduction of blood pressure and improvement in glucose and lipid metabolism. These findings suggest the beneficial role of atrasentan in the treatment of hypertension and metabolic syndrome.

The normal action of insulin to vasodilate and redistribute blood flow in support of skeletal muscle metabolism is impaired in insulin-resistant states. Increased endogenous endothelin contributes to endothelial dysfunction in obesity and diabetes. Here, we test the hypothesis that increased endogenous endothelin action also contributes to skeletal muscle insulin resistance via impairments in insulin-stimulated vasodilation. We studied nine lean and seven obese humans, measuring the metabolic and hemodynamic effects of insulin (300 mU . m(-2) . min(-1)) alone and during femoral artery infusion of BQ123 (an antagonist of type A endothelin receptors, 1 micromol/min). Endothelin antagonism augmented skeletal muscle responses to insulin in obese subjects through changes in both leg blood flow (LBF) and glucose extraction. Insulin-stimulated LBF was significantly increased in obese subjects only. These changes, combined with differential effects on glucose extraction, resulted in augmented insulin-stimulated leg glucose uptake in obese subjects (54.7 +/- 5.7 vs. 107.4 +/- 18.9 mg/min with BQ123), with no change in lean subjects (103.7 +/- 11.4 vs. 88.9 +/- 16.3, P = 0.04 comparing BQ123 across groups). BQ123 allowed augmented leg glucose extraction in obese subjects even in the face of NOS antagonism. These findings suggest that increased endogenous endothelin action contributes to insulin resistance in skeletal muscle of obese humans, likely through both vascular and tissue effects.

To quantify changes in endothelium-derived factors and relate those changes to various aspects of digital hemodynamics during the prodromal stages of carbohydrate overload (CHO)-induced laminitis in horses.

20 adult horses without abnormalities of the digit.

Digital and jugular venous blood samples were collected at 1-hour intervals (for assessment of endothelin-1 [ET-1] immunoreactivity and measurement of glucose, insulin, and nitric oxide [NO] concentrations) or 4-hour intervals (CBC and platelet-neutrophil aggregate assessment) for 8 hours or 16 hours after induction of CHO-associated laminitis in horses treated with an ET-1 antagonist. Effects of treatment, collection site, and time and the random effects of horse on each variable were analyzed by use of a repeated-measures model. Where treatment and collection site had no significant effect, data were combined.

Compared with baseline values, CHO resulted in changes in several variables, including a significant increase from baseline in digital blood ET-like immunoreactivity at 11 hours; digital blood ET-like immunoreactivity was significantly greater than that in jugular venous blood at 8, 9, 11, and 12 hours. Digital and jugular venous blood concentrations of glucose increased from baseline significantly at 3, 4, and 5 hours; insulin concentration increased significantly at 5 hours; and the number of platelet-neutrophil aggregates increased significantly at 12 hours.

In horses, concurrent increases in venous blood ET-1 immunoreactivity, insulin and glucose concentrations, and platelet-neutrophil aggregates support a role of endothelial dysfunction in the pathogenesis of CHO-induced laminitis.

The underlying mechanisms of antipsychotic (AP)-induced weight gain are unknown, but both central and peripheral AP target receptors could potentially be involved. This study used radioligand binding assays to compare the binding affinities of clozapine, olanzapine and haloperidol for candidate receptors potentially involved in AP-induced weight gain. Selected candidates derived from known pathways involved in body weight regulation included receptors classified as anorexigenic (bombesin receptor subtype 3, calcitonin gene-related peptide receptor, cholecystokinin receptor, melanocortin-4 receptor, neurotensin receptor 1) or orexigenic (cannabinoid receptor 1, galanin 1 receptor, melanin-concentrating hormone receptor (MCHR), neuropeptide Y1 receptor) as well as receptors involved in physiological actions related to digestion and fluid homeostasis (angiotensin II type 1 receptor, bradykinin B2 receptor, endothelin receptor, neurokinin 1 receptor, vasoactive intestinal polypeptide receptor 1). Clozapine, olanzapine and haloperidol exhibited negligible affinities to all of these receptors except for the MCHR (Ki=501 nM; haloperidol). With respect to other candidates from (neuro)transmitter systems already suggested to be involved in AP-induced weight gain, the binding profile of olanzapine resembled that of clozapine, with high affinity (Ki<10 nM) for serotonin (5-HT) 5-HT2A, 5-HT2C and 5-HT6, muscarinic M1 and histamine H1 receptors. In contrast, the binding profile of haloperidol was substantially different (high affinity only for the dopamine D1 receptor). In conclusion, we have not identified a novel binding site of the two investigated atypical AP that could contribute to the induced weight gain.