Myeloperoxidase (MPO)-derived oxidants reduce nitric oxide bioavailability and promote coronary microvascular dysfunction, cardiomyocyte stiffening and interstitial fibrosis—mechanisms implicated in the pathogenesis of heart failure with preserved and mildly reduced ejection fraction. Here, in a multicenter, randomized, double-blind, placebo-controlled, three-arm, parallel-group phase 2b trial of patients with heart failure and an ejection fraction of >40%, we evaluated whether treatment with the MPO inhibitor mitiperstat versus placebo for 48 weeks improved symptoms and exercise function at 16 weeks (the co-primary endpoints were the Kansas City Cardiomyopathy Questionnaire Total Symptom Score (KCCQ-TSS) and 6-minute walk distance (6MWD)). Secondary endpoints included changes in natriuretic peptides and inflammatory markers (up to 48 weeks) and echocardiographic parameters (up to 24 weeks). In total, 711 patients (45% women) were randomized 1:1:1 to mitiperstat 2.5 mg, mitiperstat 5 mg or placebo. Mitiperstat (pooled doses) did not improve KCCQ-TSS (placebo-corrected difference in mean change from baseline, –1.4 points (95% confidence interval (CI) –3.9, 1.2; P = 0.29), 6MWD (3.8 m (95% CI –3.1, 10.8)); P = 0.28) or any secondary endpoint. Adverse and serious adverse events, including infections, were similar among groups except for maculopapular rash (mitiperstat, 3.6%; placebo, 0.4%). These results indicate that mitiperstat was safe and well tolerated but did not improve symptoms or exercise function in chronic heart failure with preserved or mildly reduced ejection fraction. ClinicalTrials.gov registration: NCT04986202 . In a phase 2 randomized clinical trial, treatment with the myeloperoxidase (MPO) inhibitor mitiperstat, intended to target the neutrophil–MPO inflammatory pathway, did not improve symptoms or exercise function in individuals with heart failure with preserved or mildly reduced ejection fraction.

Background The lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) mediates atherosclerotic plaque inflammation and vulnerability. On activation, LOX-1 sheds its extracellular domain into the circulation as soluble LOX-1 (sLOX-1). sLOX-1 is markedly elevated in patients with acute coronary syndrome (ACS). Methods We prospectively assessed the associations between plasma sLOX-1 and the development of heart failure (HF), major adverse cardiovascular events (MACE) and coronary and left ventricular (LV) dysfunction in two cohorts of patients with ACS. The first cohort comprised 524 patients recruited during the acute index event at the coronary care unit of Skåne University Hospital, Malmö, Sweden. The second cohort included 363 patients with ACS treated with acute percutaneous intervention at Sahlgrenska University Hospital, Gothenburg, Sweden. Additionally, we examined the anti-inflammatory effects of LOX-1 blockade in vitro using human umbilical vein endothelial cells (HUVECs). Results In the first cohort, acute-phase sLOX-1 was associated with incident HF and MACE independently of cardiovascular risk factors, revascularisation and medication (HR per 1-SD sLOX-1 increase: 1.57 (95% CI: 1.10 to 2.23; p=0.012) for HF and 1.36 (1.08 to 1.71; p=0.009) for MACE). Elevated sLOX-1 was also associated with lower LV ejection fraction and accelerated remodelling, as measured by echocardiography at 1-year post-ACS. In the second cohort, sLOX-1 was negatively associated with left anterior descending coronary artery flow reserve and LV systolic function, and positively correlated with soluble markers of systemic inflammation and cardiac overload at 4 and 16 weeks post-ACS. In vitro, antibody-mediated LOX-1 blockade prevented oxidised low-density lipoprotein-induced HUVEC activation. Conclusions Elevated plasma sLOX-1 at baseline and during follow-up is associated with incident HF and MACE, as well as cardiac and coronary dysfunction in patients with ACS. As plasma sLOX-1 levels may reflect the intensity of LOX-1 expression on vascular and immune cells, these findings support LOX-1 as a potentially important therapeutic target to improve prognosis in patients with ACS.

Background:Explanted hearts from recipients undergoing cardiac transplantation may be utilized as a human model of cardiomyopathy. Ex-situ perfusion of hearts allows control of the physiological and biochemical conditions of perfusion. AZD8601 is a novel modRNA for VEGF-A that was shown to be safe in a Phase IIa clinical trial - the EPICCURE trial. This proof-of-concept study aimed to demonstrate the potential utility of testing novel therapies on explanted recipient hearts using ex situ machine perfusion. Methods:In order to ascertain the expression of VEGF-A in a human model of cardiomyopathy, AZD8601 was injected at high- and low-dose into the mid-myocardium of the left ventricle of human hearts explanted at the time of cardiac transplantation and perfused on the m0rgan, a novel, normothermic organ perfusion machine. Hearts were perfused ex situ for 6 h. After which, injection sites were biopsied and divided into subendocardium, mid-myocardium and sub-epicardial myocardium. Immuno-analysis was performed to assess levels of VEGF-A protein. Results:There were elevated levels of VEGF-A protein in the subendocardium and mid-myocardium of injection sites which received AZD8601. Low-dose and high-dose AZD8601 resulted in a significantly higher concentration of VEGF-A protein in the myocardium. Conclusions:This study builds on the EPICCURE study, a phase IIa clinical trial which demonstrated safety of this mRNA in patients undergoing coronary artery bypass grafting. This study provides a novel model of diseased human heart for experimental studies utilizing ex situ heart perfusion.

The lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is a key scavenger receptor for oxidized low-density lipoprotein cholesterol (oxLDL), which promotes inflammation and atherosclerosis. Here we evaluated MEDI6570, an antibody that acts as a LOX-1 antagonist, in a randomized, double-blind, dose-finding study in patients with myocardial infarction (MI) and residual inflammation (high-sensitivity C-reactive protein ≥ 1 mg l-1). At 30-365 days after MI, 423 patients (75 women, 348 men) were randomly allocated to 50 mg, 150 mg or 400 mg MEDI6570 or placebo treatment subcutaneously every 4 weeks for 32 weeks. The primary endpoint, the change in the noncalcified plaque volume in the most diseased coronary segment (NCPVMD) by computed tomography angiography, was not significantly different between placebo and MEDI6570 at any dose. The secondary endpoints, global NCPV and low-attenuation plaque volume, were also not different between placebo and MEDI6570 at any dose (all placebo-adjusted comparisons, P > 0.05). With regard to exploratory endpoints, there were reductions in free soluble LOX-1 (sLOX-1) from baseline by 44.8%, 85.8%, 94.0% and 96.4% in the placebo, 50 mg, 150 mg and 400 mg dose arms, respectively (all placebo-adjusted comparisons P < 0.001). Interleukin-6 (IL-6) levels decreased by 2.9%, -3.0%, 18.9% and 21.5% in the placebo, 50 mg, 150 mg and 400 mg arms, respectively, with substantial placebo-adjusted reductions observed only at 150 mg and 400 mg (P < 0.05). MEDI6570 was well tolerated and rates of serious adverse events were similar in the MEDI6570 and placebo groups. In summary, despite favorable effects on sLOX-1 and IL-6, a LOX-1 inhibitor did not reduce noncalcified coronary plaque volume in patients with residual inflammation after acute MI. EudraCT registration: 2020-000840-75 .

Aims: Mitiperstat is a novel, highly potent myeloperoxidase inhibitor being evaluated in patients with cardio-metabolic disease (phase 2). These patients often have impaired renal function, which may affect mitiperstat pharmacokinetics. This study assessed mitiperstat pharmacokinetics, safety and tolerability in participants with severe renal impairment and normal renal function, to inform inclusion of participants with estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m(2) in phase 3. Methods: Participants with severe renal impairment (eGFR >= 15 and <30 mL/min/1.73 m(2)) who were not on dialysis (n = 10) and group-matched controls (eGFR >= 90 mL/min/1.73 m(2); n = 10) received a single mitiperstat 2.5 mg oral tablet. Blood samples were collected at intervals for 2 weeks and urine samples for 24 h post-dose. Results: Total apparent mitiperstat clearance was 10.83 L/h in the severe renal impairment cohort and 25.62 L/h in the control cohort. The area under the plasma concentration-time curve was 2.37-fold higher (90% confidence interval [CI]: 1.79, 3.12) in the severe renal impairment cohort than in the control cohort, with longer elimination half-life and similar maximum concentration. Non-renal clearance was similar between the cohorts. Conclusions: Mitiperstat apparent clearance was approximately twofold lower in individuals with severe renal impairment than in those with normal renal function. Lower clearance was driven by reduced renal clearance; non-renal clearance was similar. Mitiperstat was generally well tolerated by participants with severe renal impairment and normal renal function. These findings, together with efficacy and safety/tolerability data from phase 2b, will guide the dosing regimen for phase 3.

BACKGROUND AND OBJECTIVE:Mitiperstat (AZD4831) is a novel irreversible oral myeloperoxidase inhibitor in clinical development for heart failure with preserved ejection fraction, metabolic dysfunction-associated steatohepatitis and chronic obstructive pulmonary disease. This study evaluated the pharmacokinetics, safety and tolerability of multiple ascending doses of mitiperstat in healthy male Japanese and Chinese volunteers. METHODS:Three cohorts of eight Japanese participants were randomized to receive once-daily oral doses of mitiperstat 2.5, 5 or 10 mg or matching placebo for 10 days (six receiving mitiperstat and two receiving placebo, per cohort). One cohort of eight Chinese participants was randomized to receive mitiperstat 5 mg or matching placebo for 10 days (six receiving mitiperstat and two receiving placebo). RESULTS:Mitiperstat was rapidly absorbed, with a time to maximum plasma concentration of 1-2 h. Exposure was dose proportional over the investigated dose range, as assessed by area under the concentration-time curve and maximum and trough plasma concentrations. Steady state was reached within 10 days, and accumulation was observed, consistent with the observed long elimination half-life of mitiperstat (50.2-57.8 h). Except for a few events of maculopapular rash, mitiperstat up to 5 mg was well tolerated in participants of Japanese or Chinese origin. CONCLUSIONS:The pharmacokinetics of mitiperstat were similar among Japanese and Chinese participants. These characteristics were similar to those in a previous multiple ascending-dose study in healthy primarily white and Black/African American volunteers. Therefore, the pharmacokinetics of mitiperstat do not affect dosing regimens in these different populations. TRIAL REGISTRATION:NCT04232345 (03/01/2020).

Background Blockade of the lectin‐like oxidized low‐density lipoprotein receptor‐1 (LOX‐1) is a potentially attractive mechanism for lowering inflammatory and lipid risk in patients with atherosclerosis. This study aims to assess the safety, tolerability, and target engagement of MEDI6570, a high‐affinity monoclonal blocking antibody to LOX‐1. Methods and Results This phase 1, first‐in‐human, placebo‐controlled study (NCT03654313) randomized 88 patients with type 2 diabetes to receive single ascending doses (10, 30, 90, 250, or 500 mg) or multiple ascending doses (90, 150, or 250 mg once monthly for 3 months) of MEDI6570 or placebo. Primary end point was safety; secondary and exploratory end points included pharmacokinetics, immunogenicity, free soluble LOX‐1 levels, and change in coronary plaque volume. Mean age was 57.6/58.1 years in the single ascending doses/multiple ascending doses groups, 31.3%/62.5% were female, and mean type 2 diabetes duration was 9.7/8.7 years. Incidence of adverse events was similar among cohorts. MEDI6570 exhibited nonlinear pharmacokinetics, with terminal half‐life increasing from 4.6 days (30 mg) to 11.2 days (500 mg), consistent with target‐mediated drug disposition. Dose‐dependent reductions in mean soluble LOX‐1 levels from baseline were observed (>66% at 4 weeks and 71.61–82.96% at 10 weeks in the single ascending doses and multiple ascending doses groups, respectively). After 3 doses, MEDI6570 was associated with nonsignificant regression of noncalcified plaque volume versus placebo (−13.45 mm3 versus −8.25 mm3). Conclusions MEDI6570 was well tolerated and demonstrated dose‐dependent soluble LOX‐1 suppression and a pharmacokinetic profile consistent with once‐monthly dosing. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT03654313.

AIMS:The vascular endothelial growth factor (VEGF) family is involved in pathophysiological mechanisms underlying cardiovascular (CV) diseases. The aim of this study was to investigate the associations between circulating VEGF ligands and/or soluble receptors and CV outcome in patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS).METHODS AND RESULTS:Levels of VEGF biomarkers, including bFGF, Flt-1, KDR (VEGFR2), PlGF, Tie-2, VEGF-A, VEGF-C, and VEGF-D, were measured in the PLATO ACS cohort (n = 2091, discovery cohort). Subsequently, VEGF-D was also measured in the STABILITY CCS cohort (n = 4015, confirmation cohort) to verify associations with CV outcomes. Associations between plasma VEGF-D and outcomes were analysed by multiple Cox regression models with hazard ratios (HR [95% CI]) comparing the upper vs. the lower quartile of VEGF-D. Genome-wide association study (GWAS) of VEGF-D in PLATO identified SNPs that were used as genetic instruments in Mendelian randomization (MR) meta-analyses vs. clinical endpoints. GWAS and MR were performed in patients with ACS from PLATO (n = 10 013) and FRISC-II (n = 2952), and with CCS from the STABILITY trial (n = 10 786). VEGF-D, KDR, Flt-1, and PlGF showed significant association with CV outcomes. VEGF-D was most strongly associated with CV death (P = 3.73e-05, HR 1.892 [1.419, 2.522]). Genome-wide significant associations with VEGF-D levels were identified at the VEGFD locus on chromosome Xp22. MR analyses of the combined top ranked SNPs (GWAS P-values; rs192812042, P = 5.82e-20; rs234500, P = 1.97e-14) demonstrated a significant effect on CV mortality [P = 0.0257, HR 1.81 (1.07, 3.04) per increase of one unit in log VEGF-D].CONCLUSION:This is the first large-scale cohort study to demonstrate that both VEGF-D plasma levels and VEGFD genetic variants are independently associated with CV outcomes in patients with ACS and CCS. Measurements of VEGF-D levels and/or VEGFD genetic variants may provide incremental prognostic information in patients with ACS and CCS.

Aims Mitiperstat (formerly AZD4831) is a novel selective myeloperoxidase inhibitor. Currently, no effective therapies target comorbidity‐induced systemic inflammation, which may be a key mechanism underlying heart failure with preserved or mildly reduced ejection fraction (HFpEF/HFmrEF). Circulating neutrophils secrete myeloperoxidase, causing oxidative stress, microvascular endothelial dysfunction, interstitial fibrosis, cardiomyocyte remodelling and diastolic dysfunction. Mitiperstat may therefore improve function of the heart and other organs, and ameliorate heart failure symptoms and exercise intolerance. ENDEAVOR is a combined, seamless phase 2b–3 study of the efficacy and safety of mitiperstat in patients with HFpEF/HFmrEF. Methods In phase 2b, approximately 660 patients with heart failure and ejection fraction >40% are being randomized 1:1:1 to mitiperstat 2.5 mg, 5 mg or placebo for 48 weeks. Eligible patients have baseline 6‐min walk distance (6MWD) of 30–400 m with a <50 m difference between screening and randomization and Kansas City Cardiomyopathy Questionnaire total symptom score (KCCQ‐TSS) ≤90 points at screening and randomization. The dual primary endpoints are change from baseline to week 16 in 6MWD and KCCQ‐TSS. The sample size provides 85% power to detect placebo‐adjusted improvements of 21 m in 6MWD and 6.0 points in KCCQ‐TSS at overall two‐sided alpha of 0.05. Safety is monitored throughout treatment, with a focus on maculopapular rash. In phase 3 of ENDEAVOR, approximately 820 patients will be randomized 1:1 to mitiperstat or placebo. Conclusion ENDEAVOR is the first phase 2b–3 study to evaluate whether myeloperoxidase inhibition can improve symptoms and exercise capacity in patients with HFpEF/HFmrEF.

BACKGROUND. Oxidized apolipoprotein B (oxLDL) and oxidized ApoA-I (oxHDL) are proatherogenic. Their prognostic value for assessing high-risk plaques by coronary computed tomography angiography (CCTA) is missing.METHODS. In a prospective, observational study, 306 participants with cardiovascular disease (CVD) had extensive lipoprotein profiling. Proteomics analysis was performed on isolated oxHDL, and atherosclerotic plaque assessment was accomplished by quantitative CCTA.RESULTS. Patients were predominantly White, overweight men (58.5%) on statin therapy (43.5%). Increase in LDL-C, ApoB, small dense LDL-C (P < 0.001 for all), triglycerides (P = 0.03), and lower HDL function were observed in the high oxLDL group. High oxLDL associated with necrotic burden (NB; β = 0.20; P < 0.0001) and fibrofatty burden (FFB; β = 0.15; P = 0.001) after multivariate adjustment. Low oxHDL had a significant reverse association with these plaque characteristics. Plasma oxHDL levels better predicted NB and FFB after adjustment (OR, 2.22; 95% CI, 1.27–3.88, and OR, 2.80; 95% CI, 1.71–4.58) compared with oxLDL and HDL-C. Interestingly, oxHDL associated with fibrous burden (FB) change over 3.3 years (β = 0.535; P = 0.033) when compared with oxLDL. Combined Met136 mono-oxidation and Trp132 dioxidation of HDL showed evident association with coronary artery calcium score (r = 0.786; P < 0.001) and FB (r = 0.539; P = 0.012) in high oxHDL, whereas Met136 mono-oxidation significantly associated with vulnerable plaque in low oxHDL.CONCLUSION. Our findings suggest that the investigated oxidized lipids are associated with high-risk coronary plaque features and progression over time in patients with CVD.TRIAL REGISTRATION. ClinicalTrials.gov NCT01621594.FUNDING. National Heart, Lung, and Blood Institute at the NIH Intramural Research Program.

Vascular endothelial growth factor A (VEGF-A) has thera-peutic cardiovascular effects, but delivery challenges have impeded clinical development. We report the first clinical study of naked mRNA encoding VEGF-A (AZD8601) injected into the human heart. EPICCURE (ClinicalTrials. gov: NCT03370887) was a randomized, double-blind study of AZD8601 in patients with left ventricular ejection fraction (LVEF) 30%-50% who were undergoing elective coronary artery bypass surgery. Thirty epicardial injections of AZD8601 (total 3 mg) or placebo in citrate-buffered saline were targeted to ischemic but viable myocardial regions mapped using quantitative [15O]-water positron emission tomography. Seven patients received AZD8601 and four received placebo and were followed for 6 months. There were no deaths or treatment-related serious adverse events and no AZD8601-associated infections, immune reactions, or arrhythmias. Exploratory outcomes indicated potential improvement in LVEF, Kansas City Cardiomy-opathy Questionnaire scores, and N-terminal pro-B -type natriuretic peptide levels, but the study is limited in size, and significant efficacy conclusions are not possible from the dataset. Naked mRNA without lipid encapsulation may provide a safe delivery platform for introducing genetic material to cardiac muscle, but further studies are needed to confirm efficacy and safety in a larger patient pool.

Background Psoriasis is a chronic inflammatory condition associated with coronary artery disease risk. Uptake of oxidized low‐density lipoprotein by the lectin‐like low‐density lipoprotein receptor‐1 triggers release of the soluble extracellular domain of the receptor (sLOX‐1). We sought to characterize the relationship between sLOX‐1, inflammation, and coronary plaque progression in psoriasis. Methods and Results A total of 327 patients with psoriasis had serum sLOX‐1 levels measured at baseline by an ELISA‐based assay. Stratification by high‐sensitivity C‐reactive protein ≥4.0 mg/L (quartile 4), identified 81 participants who had coronary plaque phenotyping at baseline and were followed longitudinally by coronary computed tomography angiography. Subjects within high‐sensitivity C‐reactive protein quartile 4 were middle‐aged (51.47±12.62 years), predominantly men (54.3%) with moderate psoriasis disease severity (6.60 [interquartile range, 3.30–13.40]). In the study cohort, participants with sLOX‐1 above the median displayed increased vulnerable coronary plaque features. At baseline, sLOX‐1 was associated with total burden (rho=0.296; P=0.01), noncalcified burden (rho=0.286; P=0.02), fibro‐fatty burden (rho=0.346; P=0.004), and necrotic burden (rho=0.394; P=0.002). A strong relationship between sLOX‐1, noncalcified burden (β=0.19; P=0.03), and fibro‐fatty burden (β=0.29; P=0.003) was found in fully adjusted models at baseline and 1‐ and 4‐year follow‐up. Finally, coronary plaque features progressed over 1 year regardless of biologic or systemic treatment in subjects with high sLOX‐1. Conclusions Patients with psoriasis with both high sLOX‐1 and high‐sensitivity C‐reactive protein levels have increased coronary plaque burden associated with atherosclerotic plaque progression independent of biologic and systemic treatment. Thus, sLOX‐1 might be considered as a promising marker in coronary artery disease risk estimation beyond traditional risk factors. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01778569.

The therapeutic and research potentials of oligonucleotides (ONs) have been hampered in part by their inability to effectively escape endosomal compartments to reach their cytosolic and nuclear targets. Splice-switching ONs (SSOs) can be used with endosomolytic small molecule compounds to increase functional delivery. So far, development of these compounds has been hindered by a lack of high-resolution methods that can correlate SSO trafficking with SSO activity. Here we present in-depth characterization of two novel endosomolytic compounds by using a combination of microscopic and functional assays with high spatiotemporal resolution. This system allows the visualization of SSO trafficking, evaluation of endosomal membrane rupture, and quantitates SSO functional activity on a protein level in the presence of endosomolytic compounds. We confirm that the leakage of SSO into the cytosol occurs in parallel with the physical engorgement of LAMP1-positive late endosomes and lysosomes. We conclude that the new compounds interfere with SSO trafficking to the LAMP1-positive endosomal compartments while inducing endosomal membrane rupture and concurrent ON escape into the cytosol. The efficacy of these compounds advocates their use as novel, potent, and quick-acting transfection reagents for antisense ONs.

Introduction : Elevated circulating soluble lectin-like oxidized low-density lipoprotein receptor 1 (sLOX-1) levels are associated with risk of MACE and heart failure following acute coronary syndrome (ACS), implying that LOX-1 signaling is a culprit in cardiovascular risk. MEDI6570 is a human monoclonal antibody in clinical trials that binds to LOX-1, antagonizing the interaction with ligands including oxLDL. Methods: To determine LOX-1 risk-related biomarkers and associated pathways in response to MEDI6570, we performed Sparse Partial-Least-Squares Discriminant Analysis on transcriptomics (PBMC) and serum proteomics (OLINK) in strong versus weak responders to MEDI6570 treatment, defined by a decrease in sLOX-1, in patients with type 2 diabetes (T2D) in a single ascending dose, placebo-controlled study (NCT03654313). Biomarkers that showed concordance at three or more timepoints during treatment were further tested in an independent high-risk (T2D and/or CVD) cohort (SUMMIT; n=1231), for correlation with sLOX-1. Results: We identified biomarkers of inflammation that predominated among others, including oxidative stress, apoptosis, cellular adhesion, and migration. Of these, IL-16 and IL-18 showed significant correlation to sLOX-1 (IL-16 r=0.43, p<0.001; IL-18 r=0.44, p<0.001) in the independent SUMMIT cohort. Additionally, in a subset of the SUMMIT cohort, significant correlations were observed between baseline and 20-year follow-up levels for sLOX-1 (r=0.271, p=0.012), IL-16 (r=0.243, p=0.025), and IL-18 (r=0.459, p<0.0001), demonstrating persistent long-term elevation of these inflammatory markers in patients. We also identified neutrophil-related markers (CEACAM8, PRTN3, PGLYRP1, CPB1, GRN, LTBR) in response to MEDI6570, which have not been previously associated with LOX-1. Conclusions: Findings indicate that IL-16 and IL-18 may be potential links between LOX-1 signaling and cardiovascular risk, being modified by treatment with MEDI6570. This study also identified neutrophil-related markers in response to MEDI6570 treatment, implicating a potential role for neutrophils in LOX-1-mediated effects. A phase 2 study in patients with recent ACS and treatment with MEDI6570 or placebo is ongoing (NCT04610892).

Abstract Background/Introduction The lectin-like oxidised low-density lipoprotein receptor (LOX-1) is involved in atherosclerotic plaque inflammation and vulnerability. Plasma levels of soluble LOX-1 (sLOX-1) have previously been associated with increased risk for recurrent coronary events and mortality in patients with acute coronary syndrome (ACS). Purpose To assess the association of sLOX-1 with the development of heart failure (HF) post-ACS. Methods We measured sLOX-1 in 524 patients with ACS within 24 hours after the acute event. A subgroup of 97 of these patients completed a follow-up echocardiogram after one year. The incidence of HF-related hospitalisation and recurrent major adverse cardiovascular events (MACE), defined as recurrent ACS or cardiovascular death, was followed for a mean period of two years. In a separate cohort of 363 patients with ACS and percutaneous coronary intervention (PCI), we studied the correlations between sLOX-1, coronary flow reserve, left ventricular systolic function and systemic inflammation at two follow-up visits within four weeks and 16 weeks post-ACS, respectively. Results Baseline sLOX-1 was positively associated with the risk of HF and MACE, independently of traditional cardiovascular risk factors, revascularisation and medication. The hazard ratios and 95% confidence intervals were 1.57 (1.10–2.23), p=0.012 for HF and 1.36 (1.08–1.71), p=0.009 for MACE per standard deviation baseline sLOX-1 increase. Elevated sLOX-1 was also negatively associated with lower-left ventricular ejection fraction at one year (r=−0.263, p=0.009). In the second ACS cohort, we found that plasma sLOX-1 measured at the two follow-up visits was negatively associated with coronary flow reserve and left ventricular systolic function, and positively correlated with biomarkers of systemic inflammation and cardiac overload. Conclusion Elevated sLOX-1 is associated with the development of HF and recurrent cardiovascular events in patients with ACS. Although this association study cannot confirm causality, the results suggest LOX-1 as a potential biomarker and treatment target in patients with ACS. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): • Swedish Research Council • The Swedish Heart and Lung foundation• Swedish Foundation for Strategic Research Dnr IRC15-0067 • Marianne and Marcus Wallenberg Foundation • Bundy Academy at Lund University

RNA-based therapies have great potential to treat many undruggable human diseases. However, their efficacy, in particular for mRNA, remains hampered by poor cellular delivery and limited endosomal escape. Development and optimisation of delivery vectors, such as lipid nanoparticles (LNPs), are impeded by limited screening methods to probe the intracellular processing of LNPs in sufficient detail. We have developed a high-throughput imaging-based endosomal escape assay utilising a Galectin-9 reporter and fluorescently labelled mRNA to probe correlations between nanoparticle-mediated uptake, endosomal escape frequency, and mRNA translation. Furthermore, this assay has been integrated within a screening platform for optimisation of lipid nanoparticle formulations. We show that Galectin-9 recruitment is a robust, quantitative reporter of endosomal escape events induced by different mRNA delivery nanoparticles and small molecules. We identify nanoparticles with superior escape properties and demonstrate cell line variances in endosomal escape response, highlighting the need for fine-tuning of delivery formulations for specific applications.