Myeloperoxidase Inhibition in Heart Failure With Preserved or Mildly Reduced Ejection Fraction: SATELLITE Trial Results.

BACKGROUND: Inflammation is a key driver of heart failure with preserved left ventricular ejection fraction. AZD4831 inhibits extracellular myeloperoxidase, decreases inflammation, and improves microvascular function in preclinical disease models. METHODS AND RESULTS: In this double-blind phase 2a study (Safety and Tolerability Study of AZD4831 in Patients With Heart Failure [SATELLITE]; NCT03756285), patients with symptomatic heart failure, left ventricular ejection fraction of ≥40%, and elevated B-type natriuretic peptides were randomized 2:1 to once-daily oral AZD4831 5 mg or placebo for 90 days. We aimed to assess target engagement (primary end point: myeloperoxidase specific activity) and safety of AZD4831. Owing to coronavirus disease 2019, the study was terminated early after randomizing 41 patients (median age 74.0 years, 53.7% male). Myeloperoxidase activity was decreased by more than 50% from baseline to day 30 and day 90 in the AZD4831 group, with a placebo-adjusted decreased of 75% (95% confidence interval, 48, 88, nominal P < .001). No improvements were noted in secondary or exploratory end points, apart from a trend in Kansas City Cardiomyopathy Questionnaire overall summary score. No deaths or treatment-related serious adverse events occurred. AZD4831 treatment-related adverse events were generalized maculopapular rash, pruritus, and diarrhea (all n = 1). CONCLUSIONS: AZD4831 inhibited myeloperoxidase and was well tolerated in patients with heart failure and left ventricular ejection fraction of 40% or greater. Efficacy findings were exploratory owing to early termination, but warrant further clinical investigation of AZD4831. LAY SUMMARY: Few treatments are available for patients with the forms of heart failure known as heart failure with preserved or mildly reduced ejection fraction. Current treatments do not target inflammation, which may play an important role in this condition. We tested a new drug called AZD4831 (mitiperstat), which decreases inflammation by inhibiting the enzyme myeloperoxidase. Among the 41 patients in our clinical trial, AZD4831 had a good safety profile and inhibited myeloperoxidase by the expected amount. Results mean we can conduct further trials to see whether AZD4831 decreases the symptoms of heart failure and improves patients' ability to participate in physical exercise.

Application of Accelerator Mass Spectrometry to Characterize the Mass Balance Recovery and Disposition of AZD4831, a Novel Myeloperoxidase Inhibitor, following Administration of an Oral Radiolabeled Microtracer Dose in Humans.

This study evaluated the mass balance and disposition of AZD4831, a novel myeloperoxidase inhibitor, in six healthy participants using a 14C-labeled microtracer coupled with analysis by accelerator mass spectrometry (AMS). A single oral dose of 10 mg 14C-AZD4831 (14.8 kBq) was administered as a solution, and 14C levels were quantified by AMS in blood, urine, and feces over 336 hours postdose. AZD4831 was rapidly absorbed, and AZD4831 plasma concentrations declined in a biphasic manner, with a long half-life of 52 hours. AZD4831 was eliminated via metabolism and renal excretion. An N-carbamoyl glucuronide metabolite of AZD4831 (M7), formed primarily via UGT1A1, was the predominant circulating metabolite. Presumably, M7 contributed to the long half-life of AZD4831 via biliary elimination and hydrolysis/enterohepatic recirculation of AZD4831. On average, ∼84% of administered 14C-AZD4831 was recovered by 336 hours postdose (urine, 51.2%; feces, 32.4%). Between 32%-44% of the dose was excreted as unchanged AZD4831 in urine, indicating renal elimination as the major excretory route. Only 9.7% of overall fecal recovery was recorded in the first 48 hours, with the remainder excreted over 48%-336 hours, suggesting that most fecal recovery was due to biliary elimination. Furthermore, only 6% of unchanged AZD4831 was recovered in feces. Overall, the fraction of the administered AZD4831 dose absorbed was high. 14C-AZD4831 was well tolerated. These findings contribute to increasing evidence that human absorption, distribution, metabolism, and excretion studies can be performed with acceptable mass balance recovery at therapeutically relevant doses and low radiolabel-specific activity using an AMS-14C microtracer approach. SIGNIFICANCE STATEMENT: In this study, the human absorption, distribution, metabolism, and excretion (hADME) of the novel myeloperoxidase inhibitor AZD4831 was assessed following oral administration. This included investigation of the disposition of M7, the N-carbamoyl glucuronide metabolite. Resolution of challenges highlighted in this study contributes to increasing evidence that hADME objectives can be achieved in a single study for compounds with therapeutically relevant doses and low radiolabel-specific activity by using an AMS-14C microtracer approach, thus reducing the need for preclinical radiolabeled studies.

Discovery of AZD4831, a Mechanism-Based Irreversible Inhibitor of Myeloperoxidase, As a Potential Treatment for Heart Failure with Preserved Ejection Fraction.

Myeloperoxidase is a promising therapeutic target for treatment of patients suffering from heart failure with preserved ejection fraction (HFpEF). We aimed to discover a covalent myeloperoxidase inhibitor with high selectivity for myeloperoxidase over thyroid peroxidase, limited penetration of the blood-brain barrier, and pharmacokinetics suitable for once-daily oral administration at low dose. Structure-activity relationship, biophysical, and structural studies led to prioritization of four compounds for in-depth safety and pharmacokinetic studies in animal models. One compound (AZD4831) progressed to clinical studies on grounds of high potency (IC50, 1.5 nM in vitro) and selectivity (>450-fold vs thyroid peroxidase in vitro), the mechanism of irreversible inhibition, and the safety profile. Following phase 1 studies in healthy volunteers and a phase 2a study in patients with HFpEF, a phase 2b/3 efficacy study of AZD4831 in patients with HFpEF started in 2021.

Safety and efficacy of the 5-lipoxygenase-activating protein inhibitor AZD5718 in patients with recent myocardial infarction: The phase 2a FLAVOUR study.

BACKGROUND: Leukotrienes are pro-inflammatory vasoactive lipid mediators implicated in the pathophysiology of atherosclerotic cardiovascular disease. We studied the effect of the 5-lipoxygenase-activating protein inhibitor AZD5718 on leukotriene biosynthesis and coronary microvascular function in a single-blind, phase 2a study. METHODS: Patients 7-28 days after myocardial infarction (±ST elevation), with <50% left anterior descending coronary artery stenosis and Thrombolysis in Myocardial Infarction flow grade ≥ 2 after percutaneous coronary intervention, were randomized 2:1:2 to once-daily AZD5718 200 mg or 50 mg, or placebo, in 4- and 12-week cohorts. Change in urine leukotriene E4 (uLTE4) was the primary endpoint, and coronary flow velocity reserve (CFVR; via echocardiography) was the key secondary endpoint. RESULTS: Of 129 randomized patients, 128 received treatment (200 mg, n = 52; 50 mg, n = 25; placebo, n = 51). Statistically significant reductions in uLTE4 levels of >80% were observed in both AZD5718 groups versus the placebo group at 4 and 12 weeks. No significant changes in CFVR were observed for AZD5718 versus placebo. Adverse events (AEs) occurred in 12/18, 3/6 and 6/13 patients receiving 200 mg, 50 mg and placebo, respectively, in the 4-week cohort, and in 27/34, 14/19 and 24/38 patients, respectively, in the 12-week cohort. Serious AEs in seven patients receiving AZD5718 and four receiving placebo were not treatment-related, and there were no deaths. CONCLUSIONS: In patients with recent myocardial infarction, AZD5718 was well tolerated, and leukotriene biosynthesis was dose-dependently inhibited. No significant changes in CFVR were detected. CLINICALTRIALS: gov identifier: NCT03317002.

Design of FLAIR: a Phase 2b Study of the 5-Lipoxygenase Activating Protein Inhibitor AZD5718 in Patients With Proteinuric CKD.

INTRODUCTION: Patients with chronic kidney disease (CKD) remain at risk for kidney and cardiovascular events resulting from residual albuminuria, despite available treatments. Leukotrienes are proinflammatory and vasoconstrictive lipid mediators implicated in the etiology of chronic inflammatory diseases. AZD5718 is a potent, selective, and reversible 5-lipoxygenase activating protein (FLAP) inhibitor that suppresses leukotriene production. METHODS: FLAIR (FLAP Inhibition in Renal disease) is an ongoing phase 2b, randomized, double-blind, placebo-controlled, multicenter study to evaluate the efficacy and safety of AZD5718 in patients with proteinuric CKD with or without type 2 diabetes. Participants receive AZD5718 at 3 different doses or placebo once daily for 12 weeks, followed by an 8-week extension in which they also receive dapagliflozin (10 mg/d) as anticipated future standard of care. The planned sample size is 632 participants, providing 91% power to detect 30% reduction in urinary albumin-to-creatinine ratio (UACR) between the maximum dose of AZD5718 and placebo. The dose-response effect of AZD5718 on UACR after the dapagliflozin extension is the primary efficacy objective. Key secondary objectives are the dose-response effect of AZD5718 plus current standard of care on UACR and acute effects of treatment on the estimated glomerular filtration rate. Safety, tolerability, AZD5718 pharmacokinetics, and analyses of biomarkers that may predict or reflect response to AZD5718 are additional objectives. CONCLUSION: FLAIR will provide data on the effects of 5-lipoxygenase pathway inhibition in patients with proteinuric CKD with or without type 2 diabetes, and will form the basis for future clinical trials (ClinicalTrials.gov: NCT04492722).

Pharmacokinetics, Pharmacodynamics, and Tolerability of AZD5718, an Oral 5-Lipoxygenase-Activating Protein (FLAP) Inhibitor, in Healthy Japanese Male Subjects.

BACKGROUND AND OBJECTIVE: AZD5718, a 5-lipoxygenase-activating protein (FLAP) inhibitor, is in clinical development for treatment of coronary artery disease (CAD) and chronic kidney disease (CKD). This study evaluated AZD5718 pharmacokinetics, pharmacodynamics, and tolerability in healthy male Japanese subjects. METHODS: Four cohorts of eight Japanese subjects were randomized to receive oral doses of AZD5718 (60, 180, 360, and 600 mg) or matching placebo administered as a single dose on Day 1 and as once-daily doses from Day 3 to Day 10 in fasted conditions. Pharmacokinetic, pharmacodynamic, and safety data were collected. RESULTS: The pharmacokinetics characteristics of AZD5718 in Japanese male subjects were similar to those reported in a previous study, and the pharmacokinetics were characterized as rapid absorption with median time to reach maximum concentration (Tmax) of 1-2 h Creatine-normalized urine maximum concentration (Cmax) with mean half-lives ranging from 8 to 21 h, and supra-proportional increase in exposure over the 60-600 mg dose range evaluated. Also, an increase in steady-state area under the concentration-time curve (AUC) compared to the first dose was observed. After both single and multiple doses of AZD5718, a clear dose/concentration-effect relationship was shown for urinary leukotriene E4 (LTE4) versus AZD5718 exposure with > 80 % inhibition at plasma concentrations in the lower nM range. No clinically relevant safety and tolerability findings were observed. CONCLUSIONS: The observed pharmacokinetics and pharmacodynamics were similar to reported data for non-Japanese healthy subjects, which support further evaluation of AZD5718 at similar doses/exposures in Japanese and non-Japanese subjects for future evaluation in patients with CAD and CKD.

Early Clinical Experience With AZD4831, A Novel Myeloperoxidase Inhibitor, Developed for Patients With Heart Failure With Preserved Ejection Fraction.

We evaluated safety, tolerability, pharmacokinetics (PKs), and pharmacodynamics of AZD4831, a novel oral myeloperoxidase (MPO) inhibitor, in a randomized, single-blind, placebo-controlled study, following once-daily multiple ascending dosing to steady-state in healthy subjects. Target engagement was measured as specific MPO activity in plasma following ex vivo zymosan stimulation of whole blood. Except for generalized maculopapular rash in 4 of 13 subjects receiving the 2 highest doses, 15 and 45 mg AZD4831, no clinically relevant safety and tolerability findings were observed. AZD4831 was rapidly absorbed and plasma concentrations declined slowly with an elimination half-life of ~ 60 hours. A dose/concentration-effect relationship between MPO inhibition vs. AZD4831 exposure was established with > 50% MPO inhibition in plasma at concentrations in the low nanomolar range. Steady-state levels were achieved within 10 days. Taken together, the PK profile, the sustained dose/concentration-dependent MPO inhibition, and available clinical data support further clinical development of AZD4831 in patients with heart failure with preserved ejection fraction.

Myeloperoxidase inhibition decreases morbidity and oxidative stress in mice with cystic fibrosis-like lung inflammation.

BACKGROUND: Cystic fibrosis (CF) lung disease is characterized by severe bacterial infections, excessive neutrophilic inflammation and oxidative stress. The neutrophil enzyme myeloperoxidase (MPO), which produces hypochlorous acid, is associated with worse disease outcomes. Therefore, pharmacological inhibition of MPO in the airways has therapeutic potential. We investigated whether treating mice with an MPO inhibitor during pulmonary infection decreases oxidative stress and improves infection outcomes in mice with CF-like lung inflammation without impacting on bacterial clearance. METHODS: Transgenic ß-epithelial sodium channel (ßENaC)-overexpressing mice (n = 10) were infected with Burkholderia multivorans and treated twice daily with the MPO inhibitor AZM198 (125 µmol/kg) or vehicle administered by oral gavage for two days. Bodyweight was recorded daily. MPO activity, markers of oxidative stress, inflammatory cytokines and leukocytes numbers were measured in bronchoalveolar lavage fluid (BALF). Bacterial burden was determined in lung tissue homogenates. RESULTS: During the course of infection, mice treated with AZM198 lost less weight than vehicle-treated mice (p < 0.01). MPO activity and glutathione sulfonamide, a hypochlorous acid-specific glutathione oxidation product, were significantly lower in BALF from AZM198-treated mice (p < 0.05). The inflammatory cytokines CXCL1 and TNF-α in BALF and bacterial burden in the lung were not significantly different between treated and control mice. CONCLUSIONS: Orally administered AZM198 inhibits MPO activity in epithelial lining fluid. Blocking hypochlorous acid production in epithelial lining fluid during pulmonary infections through inhibition of MPO improves morbidity in mice with CF-like lung inflammation without interfering with clearance of bacteria. Pharmacological inhibition of MPO is an approach to limit destructive oxidative stress in cystic fibrosis lung disease in humans.

Phase 1 Pharmacokinetic Study of AZD5718 in Healthy Volunteers: Effects of Coadministration With Rosuvastatin, Formulation and Food on Oral Bioavailability.

AZD5718 is a first-in-class small-molecule anti-inflammatory drug with the potential to reduce the residual risk of cardiovascular events after myocardial infarction in patients receiving lipid-lowering statin therapy. Leukotrienes are potent proinflammatory and vasoactive mediators synthesized in leukocytes via 5-lipoxygenase and 5-lipoxygenase-activating protein (FLAP). AZD5718 is a FLAP inhibitor that dose-dependently reduced leukotriene biosynthesis in a first-in-human study. We enrolled 12 healthy men in a randomized, open-label, crossover, single-dose phase 1 pharmacokinetic study of AZD5718 to investigate a potential drug-drug interaction with rosuvastatin, and the effects of formulation and food intake (ClinicalTrials.gov identifier: NCT02963116). Rosuvastatin (10 mg) were absorbed more rapidly when coadministered with AZD5718 (200 mg), probably owing to weak inhibition of hepatic statin uptake, but relative bioavailability was unaffected (geometric least-squares mean ratio [GMR], 100%; 90% confidence interval [CI], 86%-116%). AZD5718 pharmacokinetics were unaffected by coadministration of rosuvastatin. AZD5718 (200 mg) was absorbed less rapidly when formulated as tablets than oral suspension, with reduced relative bioavailability (GMR, 72%; 90%CI, 64%-80%). AZD5718 absorption was slower when 200-mg tablets were taken after a high-fat breakfast than after fasting, but relative bioavailability was unaffected (GMR, 96%; 90%CI, 87%-106%). In post hoc pharmacodynamic simulations, plasma leukotriene B4 levels were inhibited by >90% throughout the day following once-daily AZD5718, regardless of formulation or administration with food. AZD5718 was well tolerated, with no severe or serious adverse events. These data supported the design of a phase 2a efficacy study of AZD5718 in patients with coronary artery disease.

Structural analysis identifies an escape route from the adverse lipogenic effects of liver X receptor ligands.

Liver X receptors (LXRs) are attractive drug targets for cardiovascular disease treatment due to their role in regulating cholesterol homeostasis and immunity. The anti-atherogenic properties of LXRs have prompted development of synthetic ligands, but these cause major adverse effects-such as increased lipogenesis-which are challenging to dissect from their beneficial activities. Here we show that LXR compounds displaying diverse functional responses in animal models induce distinct receptor conformations. Combination of hydrogen/deuterium exchange mass spectrometry and multivariate analysis allowed identification of LXR regions differentially correlating with anti-atherogenic and lipogenic activities of ligands. We show that lipogenic compounds stabilize active states of LXRα and LXRß while the anti-atherogenic expression of the cholesterol transporter ABCA1 is associated with the ligand-induced stabilization of LXRα helix 3. Our data indicates that avoiding ligand interaction with the activation helix 12 while engaging helix 3 may provide directions for development of ligands with improved therapeutic profiles.

Inhibition of MPO (Myeloperoxidase) Attenuates Endothelial Dysfunction in Mouse Models of Vascular Inflammation and Atherosclerosis.

Objective- Inflammation-driven endothelial dysfunction initiates and contributes to the progression of atherosclerosis, and MPO (myeloperoxidase) has been implicated as a potential culprit. On release by circulating phagocytes, MPO is thought to contribute to endothelial dysfunction by limiting NO bioavailability via formation of reactive oxidants including hypochlorous acid. However, it remains largely untested whether specific pharmacological inhibition of MPO attenuates endothelial dysfunction. We, therefore, tested the ability of a mechanism-based MPO inhibitor, AZM198, to inhibit endothelial dysfunction in models of vascular inflammation. Approach and Results- Three models of inflammation were used: femoral cuff, the tandem stenosis model of plaque rupture in Apoe-/- mice, and C57BL/6J mice fed a high-fat, high-carbohydrate diet as a model of insulin resistance. Endothelial dysfunction was observed in all 3 models, and oral administration of AZM198 significantly improved endothelial function in the femoral cuff and tandem stenosis models only. Improvement in endothelial function was associated with decreased arterial MPO activity, determined by the in vivo conversion of hydroethidine to 2-chloroethidium, without affecting circulating inflammatory cytokines or arterial MPO content. Mechanistic studies in Mpo-/- mice confirmed the contribution of MPO to endothelial dysfunction and revealed oxidation of sGC (soluble guanylyl cyclase) as the underlying cause of the observed limited NO bioavailability. Conclusions- Pharmacological inhibition of MPO is a potential strategy to limit endothelial dysfunction in vascular inflammation. Visual Overview- An online visual overview is available for this article.

Discovery and Early Clinical Development of an Inhibitor of 5-Lipoxygenase Activating Protein (AZD5718) for Treatment of Coronary Artery Disease.

5-Lipoxygenase activating protein (FLAP) inhibitors attenuate 5-lipoxygenase pathway activity and reduce the production of proinflammatory and vasoactive leukotrienes. As such, they are hypothesized to have therapeutic benefit for the treatment of diseases that involve chronic inflammation including coronary artery disease. Herein, we disclose the medicinal chemistry discovery and the early clinical development of the FLAP inhibitor AZD5718 (12). Multiparameter optimization included securing adequate potency in human whole blood, navigation away from Ames mutagenic amine fragments while balancing metabolic stability and PK properties allowing for clinically relevant exposures after oral dosing. The superior safety profile of AZD5718 compared to earlier frontrunner compounds allowed us to perform a phase 1 clinical study in which AZD5718 demonstrated a dose dependent and greater than 90% suppression of leukotriene production over 24 h. Currently, AZD5718 is evaluated in a phase 2a study for treatment of coronary artery disease.

Safety, tolerability, pharmacokinetics and effect on serum uric acid of the myeloperoxidase inhibitor AZD4831 in a randomized, placebo-controlled, phase I study in healthy volunteers.

AIMS: Myeloperoxidase activity can contribute to impaired vascular endothelial function and fibrosis in chronic inflammation-related cardiovascular disease. Here, we investigated the safety, tolerability and pharmacokinetics of the myeloperoxidase inhibitor, AZD4831. METHODS: In this randomized, single-blind, placebo-controlled, phase I, first-in-human study, healthy men in five sequential cohorts were randomized 3:1 to receive a single oral dose of AZD4831 (5, 15, 45, 135 or 405 mg) or placebo, after overnight fasting. After at least 7 days' washout, one cohort additionally received AZD4831 45 mg after a high-calorie meal. RESULTS: Forty men participated in the study (eight per cohort: AZD4831, n = 6; placebo, n = 2). AZD4831 distributed rapidly into plasma, with a half-life of 38.2-50.0 hours. The area under the plasma concentration-time curve (AUC) increased proportionally with dose (AUC0-∝ slope estimate 1.060; 95% confidence interval [CI] 0.9943, 1.127). Increases in maximum plasma concentration were slightly more than dose proportional (slope estimate 1.201; 95% CI 1.071, 1.332). Food intake reduced AZD4831 absorption rate but did not substantially affect overall exposure or plasma half-life (n = 4). Serum uric acid concentrations decreased by 71.77 (95% CI 29.15, 114.39) and 84.42 (58.90, 109.94) µmol L-1 with AZD4831 135 mg and 405 mg, respectively. Maculopapular rash (moderate intensity) occurred in 4/30 participants receiving AZD4831 (13.3%). No other safety concerns were identified. CONCLUSIONS: AZD4831 was generally well tolerated, rapidly absorbed, had a long plasma half-life and lowered uric acid concentrations after single oral doses in healthy men. These findings support the further clinical development of AZD4831.

Myeloperoxidase is a potential molecular imaging and therapeutic target for the identification and stabilization of high-risk atherosclerotic plaque.

Aims: As the inflammatory enzyme myeloperoxidase (MPO) is abundant in ruptured human atherosclerotic plaques, we aimed to investigate the role of MPO as a potential diagnostic and therapeutic target for high-risk plaque. Methods and results: We employed the tandem stenosis model of atherosclerotic plaque instability in apolipoprotein E gene knockout (Apoe-/-) mice. To test the role of MPO, we used Mpo-/-Apoe-/- mice and the 2-thioxanthine MPO inhibitor AZM198. In vivo MPO activity was assessed by liquid chromatography-tandem mass spectrometry detection of 2-chloroethidium generation from hydroethidine and by bis-5HT-DTPA-Gd (MPO-Gd) molecular magnetic resonance imaging (MRI), while plaque phenotype was verified histologically. Myeloperoxidase activity was two-fold greater in plaque with unstable compared with stable phenotype. Genetic deletion of MPO significantly increased fibrous cap thickness, and decreased plaque fibrin and haemosiderin content in plaque with unstable phenotype. AZM198 inhibited MPO activity and it also increased fibrous cap thickness and decreased fibrin and haemosiderin in plaque with unstable phenotype, without affecting lesion monocytes and red blood cell markers or circulating leukocytes and lipids. MPO-Gd MRI demonstrated sustained enhancement of plaque with unstable phenotype on T1-weighted imaging that was two-fold greater than stable plaque and was significantly attenuated by both AZM198 treatment and deletion of the Mpo gene. Conclusion: Our data implicate MPO in atherosclerotic plaque instability and suggest that non-invasive imaging and pharmacological inhibition of plaque MPO activity hold promise for clinical translation in the management of high-risk coronary artery disease.

Initial Clinical Experience with AZD5718, a Novel Once Daily Oral 5-Lipoxygenase Activating Protein Inhibitor.

We evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of AZD5718, a novel 5-lipooxygenase activating protein (FLAP) inhibitor, in a randomized, single-blind, placebo-controlled, first-in-human (FIH) study consisting of single and multiple ascending dosing (SAD and MAD) for 10 days in healthy subjects. Target engagement was measured by ex vivo calcium ionophore stimulated leukotriene B (LTB4 ) production in whole blood and endogenous leukotriene E (LTE4 ) in urine. No clinically relevant safety and tolerability findings were observed. The AZD5718 was rapidly absorbed and plasma concentrations declined biphasically with a mean terminal half-life of 10-12 h. Steady-state levels were achieved after ∼3 days. After both SADs and MADs, a dose/concentration-effect relationship between both LTB4 and LTE4 vs. AZD5718 exposure was observed with concentration of half inhibition (IC50 ) values in the lower nM range. Based on obtained result, AZD5718 is considered as a suitable drug candidate for future evaluation in patients with coronary artery disease (CAD).

The liver X receptor agonist AZ876 protects against pathological cardiac hypertrophy and fibrosis without lipogenic side effects.

AIMS: Liver X receptors (LXRs) transcriptionally regulate inflammation, metabolism, and immunity. Synthetic LXR agonists have been evaluated for their efficacy in the cardiovascular system; however, they elicit prolipogenic side effects which substantially limit their therapeutic use. AZ876 is a novel high-affinity LXR agonist. Herein, we aimed to determine the cardioprotective potential of LXR activation with AZ876. METHODS AND RESULTS: Cardiac hypertrophy was induced in C57Bl6/J mice via transverse aortic constriction (TAC) for 6 weeks. During this period, mice received chow supplemented or not with AZ876 (20 µmol/kg/day). In murine hearts, LXRα protein expression was up-regulated ∼7-fold in response to TAC. LXR activation with AZ876 attenuated this increase, and significantly reduced TAC-induced increases in heart weight, myocardial fibrosis, and cardiac dysfunction without affecting blood pressure. At the molecular level, AZ876 suppressed up-regulation of hypertrophy- and fibrosis-related genes, and further inhibited prohypertrophic and profibrotic transforming growth factor ß (TGFß)-Smad2/3 signalling. In isolated cardiac myocytes and fibroblasts, immunocytochemistry confirmed nuclear expression of LXRα in both these cell types. In cardiomyocytes, phenylephrine-stimulated cellular hypertrophy was significantly decreased in AZ876-treated cells. In cardiac fibroblasts, AZ876 prevented TGFß- and angiotensin II-induced fibroblast collagen synthesis, and inhibited up-regulation of the myofibroblastic marker, α-smooth muscle actin. Plasma triglycerides and liver weight were unaltered following AZ876 treatment. CONCLUSION: AZ876 activation of LXR protects from adverse cardiac remodelling in pathological pressure overload, independently of blood pressure. LXR may thus represent a putative molecular target for antihypertrophic and antifibrotic therapies in heart failure prevention.