Mechanisms of blood-retinal barrier disruption related to intraocular inflammation and malignancy

Blood-retinal barrier (BRB) disruption is a common accompaniment of intermediate, posterior and panuveitis causing leakage into the retina and macular oedema resulting in vision loss. It is much less common in anterior uveitis or in patients with intraocular lymphoma who may have marked signs of intraocular inflammation. New drugs used for chemotherapy (cytarabine, immune checkpoint inhibitors, BRAF inhibitors, EGFR inhibitors, bispecific anti-EGFR inhibitors, MET receptor inhibitors and Bruton tyrosine kinase inhibitors) can also cause different types of uveitis and BRB disruption. As malignant disease itself can cause uveitis, particularly from breast, lung and gastrointestinal tract cancers, it can be clinically difficult to sort out the cause of BRB disruption. Immunosuppression due to malignant disease and/or chemotherapy can lead to infection which can also cause BRB disruption and intraocular infection. In this paper we address the pathophysiology of BRB disruption related to intraocular inflammation and malignancy, methods for estimating the extent and effect of the disruption and examine why some types of intraocular inflammation and malignancy cause BRB disruption and others do not. Understanding this may help sort and manage these patients, as well as devise future therapeutic approaches.

Impact of diabetes on remodelling, microvascular function and exercise capacity in aortic stenosis

OBJECTIVE

To characterise cardiac remodelling, exercise capacity and fibroinflammatory biomarkers in patients with aortic stenosis (AS) with and without diabetes, and assess the impact of diabetes on outcomes.

METHODS

Patients with moderate or severe AS with and without diabetes underwent echocardiography, stress cardiovascular magnetic resonance (CMR), cardiopulmonary exercise testing and plasma biomarker analysis. Primary endpoint for survival analysis was a composite of cardiovascular mortality, myocardial infarction, hospitalisation with heart failure, syncope or arrhythmia. Secondary endpoint was all-cause death.

RESULTS

Diabetes (n=56) and non-diabetes groups (n=198) were well matched for age, sex, ethnicity, blood pressure and severity of AS. The diabetes group had higher body mass index, lower estimated glomerular filtration rate and higher rates of hypertension, hyperlipidaemia and symptoms of AS. Biventricular volumes and systolic function were similar, but the diabetes group had higher extracellular volume fraction (25.9%±3.1% vs 24.8%±2.4%, p=0.020), lower myocardial perfusion reserve (2.02±0.75 vs 2.34±0.68, p=0.046) and lower percentage predicted peak oxygen consumption (68%±21% vs 77%±17%, p=0.002) compared with the non-diabetes group. Higher levels of renin (log10renin: 3.27±0.59 vs 2.82±0.69 pg/mL, p<0.001) were found in diabetes. Multivariable Cox regression analysis showed diabetes was not associated with cardiovascular outcomes, but was independently associated with all-cause mortality (HR 2.04, 95% CI 1.05 to 4.00; p=0.037).

CONCLUSIONS

In patients with moderate-to-severe AS, diabetes is associated with reduced exercise capacity, increased diffuse myocardial fibrosis and microvascular dysfunction, but not cardiovascular events despite a small increase in mortality.

Early prediction of left ventricular function improvement in patients with new-onset heart failure and presumed non-ischaemic aetiology

OBJECTIVES

To determine baseline characteristics predictive of left ventricular ejection fraction (LVEF) recovery in patients diagnosed with heart failure with reduced ejection fraction (HFrEF) and presumed non-ischaemic aetiology.

METHODS

We prospectively recruited patients who were diagnosed with HFrEF (LVEF ≤40%) on echocardiography and subsequently underwent cardiac MRI. Patients were excluded if they had a known history of coronary artery disease (>70% on invasive coronary angiography), myocardial infarction, coronary revascularisation or anginal symptoms. At cardiac MRI assessment, patients were categorised as either ongoing HFrEF or heart failure with improved ejection fraction (HFimpEF, LVEF >40% with ≥10% of absolute improvement). Clinical characteristics were compared between the groups. Logistic regression was performed to identify variables that were associated with LVEF recovery. Optimal cut-offs in QRISK3 score and baseline LVEF for prediction of LVEF recovery were identified through receiver operating characteristic curve analysis.

RESULTS

A total of 407 patients were diagnosed with HFrEF, and 139 (34%) attained HFimpEF at cardiac MRI assessment (median 63 days, IQR 41-119 days). Mean age of the patients was 63±12 years, and 260 (63.9%) were male. At multivariate logistic regression, both QRISK3 score (HR 0.978; 95% CI 0.963 to 0.993, p=0.004) and baseline LVEF (HR 1.044; 95% CI 1.015 to 1.073, p=0.002) were independent predictors of HFimpEF. Among patients with baseline LVEF ≤25%, only 22 (21.8%) recovered. In patients with baseline LVEF 25-40%, QRISK3 score >18% was associated with lack of recovery (HR 2.75; 95% CI 1.70 to 4.48, p<0.001). Additionally, QRISK3 score was associated with the presence of ischaemic late gadolinium enhancement (HR 1.035; 95% CI 1.018 to 1.053, p<0.001).

CONCLUSIONS

The QRISK3 score helps identify patients with HFrEF with undiagnosed vascular disease. Patients with either a very low baseline LVEF or a high QRISK3 score have less chance of left ventricular recovery and should be prioritised for early cardiac MRI and close monitoring.

A survey in the West Midlands of the United Kingdom of current practice in managing hypotension in lower segment caesarean section under spinal anaesthesia

BACKGROUND

Spinal anaesthesia, the most common form of anaesthesia for caesarean section, leads to sympathetic blockade and profound maternal hypotension resulting in adverse maternal and neonatal outcomes. Hypotension, nausea and vomiting remain common but until the publication of the National Institute of Health and Care Excellence (NICE) 2021 guidance, no national guideline existed on how best to manage maternal hypotension following spinal anaesthesia for caesarean section. A 2017 international consensus statement recommended prophylactic vasopressor administration to maintain a systolic blood pressure of >90% of an accurate pre-spinal value, and to avoid a drop to <80% of this value. This survey aimed to assess regional adherence to these recommendations, the presence of local guidelines for management of hypotension during caesarean section under spinal anaesthesia, and the individual clinician's treatment thresholds for maternal hypotension and tachycardia.

METHODS

The West Midlands Trainee-led Research in Anaesthesia and Intensive Care Network co-ordinated surveys of obstetric anaesthetic departments and consultant obstetric anaesthetists across 11 National Health Service Trusts in the Midlands, England.

RESULTS

One-hundred-and-two consultant obstetric anaesthetists returned the survey and 73% of sites had a policy for vasopressor use; 91% used phenylephrine as the first-line drug but a wide range of recommended delivery methods was noted and target blood pressure was only listed in 50% of policies. Significant variation existed in both vasopressor delivery methods and target blood pressures.

CONCLUSIONS

Although NICE has since recommended prophylactic phenylephrine infusion and a target blood pressure, the previous international consensus statement was not adhered to routinely.

Abstract 3636: Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS

Background: 25% of patients diagnosed with colorectal cancer (CRC) have liver metastasis at presentation, and ~80% of all metastatic CRC are developed in the liver. We previously reported that liver endothelial cells (ECs), a key component of the liver microenvironment, secrete LRG1 to promote CRC growth via activating human epidermal growth factor receptor (ERbB3, also known as HER3). However, we found that LRG1-induced HER3 activation is distinct from the canonical neuregulin 1 (NRG1)-induced HER3 pathway. The present study further validated LRG1 as a new HER3 ligand for promoting mCRC growth and elucidated the novel downstream signaling pathway induced by LRG1-HER3.

Methods: We first measured the binding affinity between HER3 and LRG1 by Biolayer interferometry (BLI). We then used in vitro and in vivo xenograft approaches to determine the effect of LRG1 monoclonal antibody (15C4) on HER3 activation and CRC growth. To further determine the role of LRG1 in promoting CRC growth in the liver, we used murine CRC cells in a syngeneic orthotropic liver injection model to establish CRC allografts in the liver of LRG1−/− mice with systemic LRG1 knockout and wild-type siblings (LRG1+/+). We also performed unbiased phospho-MS analysis and subsequent validations to determine the downstream signaling pathway activated by LRG1-HER3.

Results: We identified that LRG1 binds to HER3 with the affinity at ~100nM. The LRG1 antibody 15C4 completely attenuated LRG1-induced HER3 activation and in vitro and xenograft growth in vivo. Moreover, LRG1−/− mice with CRC allografts in the liver had 2 times longer overall survival than tumor-bearing LRG1+/+ mice. Lastly, unbiased -omics analysis identified eIF4-protein synthesis is significantly activated by LRG1. With target-specific inhibitors, we further determined that LRG1-HER3 activates the PI3K-PDK1-RSK1/3-eIF4 axis independent of AKT.

Conclusions: We identified LRG1 as a novel HER3 ligand and demonstrated that the liver microenvironment-derived LRG1 plays a key oncogenic role in mCRC, by activating a novel RSK-eIF4 survival pathway. Our findings highlighted the potential of blocking LRG1-HER3 and involved downstream pathways for treating patients with mCRC.

Citation Format: Moeez Ghani Rathore, Michelle Wright, Wei Huang, Derek Taylor, Yamu Li, Jordan Winter, Zhenghe Wang, John Greenwood, Stephen Moss, Rui Wang. Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3636.

Body mass index associated differences in cardiac stress energetics in type 2 diabetes

Background

Patients with T2D and heart disease have normal body mass index (BMI), suggesting that diabetes and obesity mediate cardiovascular change by different mechanisms. Changes in cardiac energy metabolism in lean diabetic patients during exercise stress have not been previously reported.

Objectives

We aimed to assess if there are BMI-associated differences in cardiac stress metabolism in patients with T2D.

Methods

Twenty-five overweight T2D patients (O-T2D) and eleven lean T2D patients (LnT2D), age- and ethnicity-matched and with no other comorbidities were studied. Patients were on oral hypoglycaemics only and were free of diabetes complications. Participants underwent rest and dobutamine stress phosphorus magnetic resonance spectroscopy (31P-MRS) and cardiovascular magnetic resonance (CMR) at 3T for the assessment of myocardial phosphocreatine to ATP ratio (PCr/ATP) as a measure of myocardial energetics, biventricular volumes, rest and stress left ventricular (LV) ejection fraction, global longitudinal shortening, and mitral in-flow E/A ratio for assessment of diastolic function and perfusion.

Intravenous Dobutamine was administered at a dose of 10μg/kg/min, increasing at 90 second intervals up to a maximum of 40 μg/kg/min to achieve a target heart rate of 65% of the age-predicted maximal heart rate. Mean rate pressure product (RPP) was recorded at rest and stress. Heart rate was maintained at target for the duration of the 31P-MRS and stress CMR cine, mitral in-flow and perfusion acquisitions.

Results

The cardiac volumes, systolic or diastolic function and LV mass were similar between LnT2D and O-T2D. Although the O-T2D patients had a numerically lower rest and stress PCr/ATP ratio, this did not reach statistical significance. Resting PCr/ATP was reduced in LnT2D and O-T2D patients similarly. However, LnT2D showed a greater reduction in PCr/ATP (stress PCr/ATP LnT2D 1.51±0.2 vs O-T2D 1.41±0.25, p=0.02) despite similar increases in RPP. Stress myocardial blood flow (MBF) was also significantly lower in the O-T2D patients. There were significant correlations of BMI with LV mass (r=0.35, p=0.03); stress LVEF (r=−0.34, p=0.04); stress MBF stress (r=−0.53, p=0.001) and stress E/A (r=0.46, p=0.01) (figure 1).

Conclusions

Despite their better stress perfusion and similar glycaemic control, LnT2D show worse metabolic reserve characterised by more significant decrements in energetics in response to hemodynamic stress compared to overweight patients with T2D. Higher BMI correlates inversely with stress myocardial blood flow and with stress left ventricular ejection fraction. The presence of these subtle alterations in measures of stress metabolism and perfusion might signify a distinct metabolic phenotype of “lean diabetic cardiomyopathy”. Future studies are needed to further delineate alterations in cardiac energy metabolism in lean and overweight/obese type 2 diabetes patients, and their role in the development of cardiac dysfunction.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Wellcome TrustBHF

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

First Leptophobic Dark Matter Search from the Coherent-CAPTAIN-Mills Liquid Argon Detector

We report the first results of a search for leptophobic dark matter (DM) from the Coherent-CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) and 17.9×10^{20} protons on target (POT) was performed in fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light based with a threshold of 50 keV and used coherent elastic scattering off argon nuclei to detect DM. Despite only 1.5 months of accumulated luminosity, contaminated LAr, and nonoptimized shielding, CCM's first engineering run has already achieved sensitivity to previously unexplored parameter space of light dark matter models with a baryonic vector portal. With an expected background of 115 005 events, we observe 115 005+16.5 events which is compatible with background expectations. For a benchmark mediator-to-DM mass ratio of m_{V_{B}}/m_{χ}=2.1, DM masses within the range 9  MeV≲m_{χ}≲50  MeV are excluded at 90% C. L. in the leptophobic model after applying the Feldman-Cousins test statistic. CCM's upgraded run with 200 PMTs, filtered LAr, improved shielding, and 10 times more POT will be able to exclude the remaining thermal relic density parameter space of this model, as well as probe new parameter space of other leptophobic DM models.

Abstract 3180: Targeting LRG1 to normalize tumor vasculature and enhance therapeutic efficacy

In recent years improving tumor vascular function, to render the tumour microenvironment less permissive and to improve delivery of therapeutics, has gained traction due to a growing body of supportive evidence. Identifying suitable targets that are tractable, ubiquitous and safe, however, has proven to be more challenging. Almost a decade ago we reported that a secreted glycoprotein, leucine-rich alpha-2-glycoprotein 1 (LRG1), was induced in ocular neovascular complications and contributed to the formation of dysfunctional neovessels1. More recently, we have reported that LRG1 is expressed in experimental and human tumors, and that its inhibition with a function-blocking antibody improves outcome in multiple primary2 and metastatic3 models of cancer. Crucially, we found that LRG1 blockade normalizes tumor vessels and enhances the efficacy of cisplatin, adoptive T cell and checkpoint inhibitor therapy, and that a humanized version of our blocking antibody named Magacizumab effectively inhibits tumour growth both alone and as an antibody-drug-conjugate4.Using animal models and in vitro assays we present here further data in support of LRG1 as a promising target for the treatment of solid cancers. We have further investigated the effects of LRG1 blockade on immune cell infiltration using flow cytometric and immunohistochemical analysis. In subcutaneous B16 melanoma-bearing mice treated with a PD1 checkpoint inhibitor, antibody blockade of LRG1 significantly enhanced the infiltration of CD3+ and CD8+ T cells, with the latter exhibiting a more activated phenotype as evidenced by higher GrzB, reduced PD1hi expression and increased proliferation. We also observed a reduction in the Tregs:Th ratio and a higher number of MHCII+ cells. These outcomes were also observed in LLC tumors alongside a reduction in the number of infiltrated neutrophils. In preliminary studies, where we investigated LRG1 blockade in the Rag1 mouse, we observed no effect suggesting that the downstream mode of action is mediated by impacting the immune system. Finally, to test the development of our humanized anti-LRG1 antibody Magacizumab, that only recognizes human LRG1, we demonstrated its efficacy in B16F0 tumors grown in a human LRG1 knock-in mouse. These studies provide compelling evidence that LRG1 is a novel, legitimate and potentially efficacious target for the treatment of various human solid cancers. References:Wang X et al. (2013). LRG1 promotes angiogenesis by modulating endothelial TGF-β signalling. Nature 499:306-311. O’Connor MN et al. (2021). LRG1 destabilizes tumor vessels and restricts immunotherapeutic potency. Med 2:1231-1252.Singhal M et al. (2021). Temporal multi-omics identifies LRG1 as a vascular niche instructor of metastasis. Sci Transl Med. 609:eabe6805. Javaid F et al., (2021). Leucine-rich alpha-2-glycoprotein 1 (LRG1) as a novel ADC target. RSC Chem. Biol. 2:1206-1220.

Citation Format: John Greenwood, Carlotta Camilli, Camilla Pilotti, Chantelle E. Bowers, Stephen E. Moss. Targeting LRG1 to normalize tumor vasculature and enhance therapeutic efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3180.

Structural basis of human LRG1 recognition by Magacizumab, a humanized monoclonal antibody with therapeutic potential

Structural interactions between the LRG1 epitope and the Fab fragment of Magacizumab determine its specific binding mode and the key residues involved in LRG1 recognition.

The formation of new dysfunctional blood vessels is a crucial stage in the development of various conditions such as macular degeneration, diabetes, cardiovascular disease, neurological disease and inflammatory disorders, as well as during tumor growth, eventually contributing to metastasis. An important factor involved in pathogenic angiogenesis is leucine-rich α-2-glycoprotein 1 (LRG1), the antibody blockade of which has been shown to lead to a reduction in both choroidal neovascularization and tumor growth in mouse models. In this work, the structural interactions between the LRG1 epitope and the Fab fragment of Magacizumab, a humanized function-blocking IgG4 against LRG1, are analysed, determining its specific binding mode and the key residues involved in LRG1 recognition. Based on these structural findings, a series of mutations are suggested that could be introduced into Magacizumab to increase its affinity for LRG1, as well as a model of the entire Fab–LRG1 complex that could enlighten new strategies to enhance affinity, consequently leading towards an even more efficient therapeutic.

Multicenter Evaluation of Diagnostic Circulating Biomarkers to Detect Sight-Threatening Diabetic Retinopathy

Question

Can circulating serum biomarkers distinguish people with sight-threatening diabetic retinopathy (STDR) from those with no DR?

Findings

This multicenter cross-sectional study of 538 participants found an incremental benefit of circulating cystatin C beyond the standard clinical variables in discriminating STDR from no DR. Cystatin C outperformed 12 other biomarkers found to be distinguished in STDR in previous research.

Meaning

Results of this study suggest the consideration of circulating cystatin C levels as a triage test in prioritizing people with type 2 diabetes from the community for retinal screening in resource-restricted settings.

Importance

It is a global challenge to provide regular retinal screening for all people with diabetes to detect sight-threatening diabetic retinopathy (STDR).

Objective

To determine if circulating biomarkers could be used to prioritize people with type 2 diabetes for retinal screening to detect STDR.

Design, Setting, and Participants

This cross-sectional study collected data from October 22, 2018, to December 31, 2021. All laboratory staff were masked to the clinical diagnosis, assigned a study cohort, and provided with the database containing the clinical data. This was a multicenter study conducted in parallel in 3 outpatient ophthalmology clinics in the UK and 2 centers in India. Adults 40 years and older were categorized into 4 groups: (1) no history of diabetes, (2) type 2 diabetes of at least 5 years’ duration with no evidence of DR, (3) nonproliferative DR with diabetic macular edema (DME), or (4) proliferative DR. STDR comprised groups 3 and 4.

Exposures

Thirteen previously verified biomarkers were measured using enzyme-linked immunosorbent assay.

Main Outcomes and Measures

Severity of DR and presence of DME were diagnosed using fundus photographs and optical coherence tomography. Weighted logistic regression and receiver operating characteristic curve analysis (ROC) were performed to identify biomarkers that discriminate STDR from no DR beyond the standard clinical parameters of age, disease duration, ethnicity (in the UK) and hemoglobin A_1c.

Results

A total of 538 participants (mean [SD] age, 60.8 [9.8] years; 319 men [59.3%]) were recruited into the study. A total of 264 participants (49.1%) were from India (group 1, 54 [20.5%]; group 2, 53 [20.1%]; group 3, 52 [19.7%]; group 4, 105 [39.8%]), and 274 participants (50.9%) were from the UK (group 1, 50 [18.2%]; group 2, 70 [25.5%]; group 3, 55 [20.1%]; group 4, 99 [36.1%]). ROC analysis (no DR vs STDR) showed that in addition to age, disease duration, ethnicity (in the UK) and hemoglobin A_1c, inclusion of cystatin C had near-acceptable discrimination power in both countries (area under the receiver operating characteristic curve [AUC], 0.779; 95% CI, 0.700-0.857 in 215 patients in the UK with complete data; AUC, 0.696; 95% CI, 0.602-0.791 in 208 patients in India with complete data).

Conclusions and Relevance

Results of this cross-sectional study suggest that serum cystatin C had good discrimination power in the UK and India. Circulating cystatin-C levels may be considered as a test to identify those who require prioritization for retinal screening for STDR.

Coronary microvascular function and visceral adiposity in patients with normal body weight and type 2 diabetes

OBJECTIVE

This study sought to assess whether diabetes affects coronary microvascular function in individuals with normal body weight.

METHODS

Seventy-five participants (30 patients with type 2 diabetes [T2D] who were overweight [O-T2D], 15 patients with T2D who were lean [LnT2D], 15 healthy volunteers who were lean [LnHV], and 15 healthy volunteers who were overweight [O-HV]) without established cardiovascular disease were recruited. Participants underwent magnetic resonance imaging for assessment of subcutaneous, epicardial, and visceral adipose tissue areas, adenosine stress myocardial blood flow (MBF), and cardiac structure and function.

RESULTS

Stress MBF was reduced only in the O-T2D group (mean [SD], LnHV = 2.07 [0.47] mL/g/min, O-HV = 2.08 [0.42] mL/g/min, LnT2D = 2.16 [0.36] mL/g/min, O-T2D = 1.60 [0.28] mL/g/min; p ≤ 0.0001). Accumulation of visceral fat was evident in the LnT2D group at similar levels to the O-HV group (LnHV = 127 [53] cm² , O-HV = 181 [60] cm² , LnT2D = 182 [99] cm² , O-T2D = 288 [72] cm² ; p < 0.0001). Only the O-T2D group showed reductions in left ventricular ejection fraction (LnHV = 63% [4%], O-HV = 63% [4%], LnT2D = 60% [5%], O-T2D = 58% [6%]; p = 0.0008) and global longitudinal strain (LnHV = -15.1% [3.1%], O-HV= -15.2% [3.7%], LnT2D = -13.4% [2.7%], O-T2D = -11.1% [2.8%]; p = 0.002) compared with both control groups.

CONCLUSIONS

Patients with T2D and normal body weight do not show alterations in global stress MBF, but they do show significant increases in visceral adiposity. Patients with T2D who were overweight and had no prior cardiovascular disease showed an increase in visceral adiposity and significant reductions in stress MBF.

Prospective Longitudinal Characterization of the Relationship between Diabetes and Cardiac Structural and Functional Changes

OBJECTIVES

In a cohort of type 2 diabetic (T2D) patients who underwent baseline cardiac magnetic resonance (CMR) and biomarker testing, during a median follow-up of 6 years, we aimed to determine longitudinal changes in the phenotypic expression of heart disease in diabetes, report clinical outcomes, and compare baseline clinical characteristics and CMR findings of patients who experienced major adverse cardiovascular events (MACE) to those remaining MACE free.

BACKGROUND

T2D increases the risk of heart failure (HF) and cardiovascular mortality. The long-term impact of T2D on cardiac phenotype in the absence of cardiovascular disease and other clinical events is unknown.

METHODS

Patients with T2D (n = 100) with no history of cardiovascular disease or hypertension were recruited at baseline. Biventricular volumes, function, and myocardial extracellular volume fraction (ECV) were assessed by CMR, and blood biomarkers were taken. Follow-up CMR was repeated in those without interim clinical events after 6 years.

RESULTS

Follow-up was successful in 83 participants. Of those, 29 experienced cardiovascular/clinical events (36%). Of the remaining 59, 32 patients who experienced no events received follow-up CMR. In this cohort, despite no significant changes in blood pressure, weight, or glycated hemoglobin, significant reductions in biventricular end-diastolic volumes and ejection fractions occurred over time. The mean ECV was unchanged. Baseline plasma high-sensitivity cardiac troponin T (hs-cTnT) was significantly associated with a change in left ventricular (LV) ejection fraction. Patients who experienced MACE had higher LV mass and greater LV concentricity than those who remained event free.

CONCLUSIONS

T2D results in reductions in biventricular size and systolic function over time even in the absence of cardiovascular/clinical events.

LRG1 as a novel therapeutic target in eye disease

Retinal and choroidal diseases are major causes of blindness and visual impairment in the developed world and on the rise due to an ageing population and diabetes epidemic. Standard of care is centred around blockade of vascular endothelial growth factor (VEGF), but despite having halved the number of patients losing sight, a high rate of patient non-response and loss of efficacy over time are key challenges. Dysregulation of vascular homoeostasis, coupled with fibrosis and inflammation, are major culprits driving sight-threatening eye diseases. Improving our knowledge of these pathological processes should inform the development of new drugs to address the current clinical challenges for patients. Leucine-rich α-2 glycoprotein 1 (LRG1) is an emerging key player in vascular dysfunction, inflammation and fibrosis. Under physiological conditions, LRG1 is constitutively expressed by the liver and granulocytes, but little is known about its normal biological function. In pathological scenarios, such as diabetic retinopathy (DR) and neovascular age-related macular degeneration (nvAMD), its expression is ectopically upregulated and it acquires a much better understood pathogenic role. Context-dependent modulation of the transforming growth-factor β (TGFβ) pathway is one of the main activities of LRG1, but additional roles have recently been emerging. This review aims to highlight the clinical and pre-clinical evidence for the pathogenic contribution of LRG1 to vascular retinopathies, as well as extrapolate from other diseases, functions which may be relevant to eye disease. Finally, we will provide a current update on the development of anti-LRG1 therapies for the treatment of nvAMD.

LRG1: an emerging player in disease pathogenesis

The secreted glycoprotein leucine-rich α-2 glycoprotein 1 (LRG1) was first described as a key player in pathogenic ocular neovascularization almost a decade ago. Since then, an increasing number of publications have reported the involvement of LRG1 in multiple human conditions including cancer, diabetes, cardiovascular disease, neurological disease, and inflammatory disorders. The purpose of this review is to provide, for the first time, a comprehensive overview of the LRG1 literature considering its role in health and disease. Although LRG1 is constitutively expressed by hepatocytes and neutrophils, Lrg1-/- mice show no overt phenotypic abnormality suggesting that LRG1 is essentially redundant in development and homeostasis. However, emerging data are challenging this view by suggesting a novel role for LRG1 in innate immunity and preservation of tissue integrity. While our understanding of beneficial LRG1 functions in physiology remains limited, a consistent body of evidence shows that, in response to various inflammatory stimuli, LRG1 expression is induced and directly contributes to disease pathogenesis. Its potential role as a biomarker for the diagnosis, prognosis and monitoring of multiple conditions is widely discussed while dissecting the mechanisms underlying LRG1 pathogenic functions. Emphasis is given to the role that LRG1 plays as a vasculopathic factor where it disrupts the cellular interactions normally required for the formation and maintenance of mature vessels, thereby indirectly contributing to the establishment of a highly hypoxic and immunosuppressive microenvironment. In addition, LRG1 has also been reported to affect other cell types (including epithelial, immune, mesenchymal and cancer cells) mostly by modulating the TGFβ signalling pathway in a context-dependent manner. Crucially, animal studies have shown that LRG1 inhibition, through gene deletion or a function-blocking antibody, is sufficient to attenuate disease progression. In view of this, and taking into consideration its role as an upstream modifier of TGFβ signalling, LRG1 is suggested as a potentially important therapeutic target. While further investigations are needed to fill gaps in our current understanding of LRG1 function, the studies reviewed here confirm LRG1 as a pleiotropic and pathogenic signalling molecule providing a strong rationale for its use in the clinic as a biomarker and therapeutic target.

A de novo paradigm for male infertility

De novo mutations are known to play a prominent role in sporadic disorders with reduced fitness. We hypothesize that de novo mutations play an important role in severe male infertility and explain a portion of the genetic causes of this understudied disorder. To test this hypothesis, we utilize trio-based exome sequencing in a cohort of 185 infertile males and their unaffected parents. Following a systematic analysis, 29 of 145 rare (MAF < 0.1%) protein-altering de novo mutations are classified as possibly causative of the male infertility phenotype. We observed a significant enrichment of loss-of-function de novo mutations in loss-of-function-intolerant genes (p-value = 1.00 × 10^-5) in infertile men compared to controls. Additionally, we detected a significant increase in predicted pathogenic de novo missense mutations affecting missense-intolerant genes (p-value = 5.01 × 10^-4) in contrast to predicted benign de novo mutations. One gene we identify, RBM5, is an essential regulator of male germ cell pre-mRNA splicing and has been previously implicated in male infertility in mice. In a follow-up study, 6 rare pathogenic missense mutations affecting this gene are observed in a cohort of 2,506 infertile patients, whilst we find no such mutations in a cohort of 5,784 fertile men (p-value = 0.03). Our results provide evidence for the role of de novo mutations in severe male infertility and point to new candidate genes affecting fertility.

Use of Biodegradable Temporising Matrix (BTM) in the reconstruction of diabetic foot wounds: A pilot study

Introduction

Complex diabetes-related foot wounds are at high risk of infection and subsequent major amputation unless healed expediently. Biodegradable Temporising Matrix (BTM) is a synthetic matrix that facilitates the organisation of the extracellular matrix, resulting in a neodermis layer over these difficult-to-heal areas. The aim of this study was to evaluate the efficacy of using BTM in the reconstruction of challenging diabetic foot wounds.

Methods

Eighteen patients with complex diabetic foot wounds (exposed tendon, fascia, joint, bone), or chronic ulcers at high shear stress locations had BTM applied. Indications for BTM application were high shear stress location (66.6%), exposed bone (16.6%), exposed fascia (5.6%), exposed tendon (5.6%) and chronic non-healing wound (5.6%). The time to complete healing, infection rate and incidence of subsequent wound breakdown was analysed.

Discussion

Thirteen of 18 patients completed the BTM treatment regime with all these patients achieving complete wound healing at a median time of 13 weeks. One patient had partial treatment with BTM and four patients were withdrawn from the study following BTM application. The rate of infection and re-ulceration were both 15.4%.

Conclusion

This is the first prospective cohort pilot study evaluating the use of BTM for complex diabetic foot wounds. BTM demonstrates potential in healing uninfected, non-ischaemic diabetic foot wounds with exposed deep structures and chronic wounds subject to high shear stress. The re-ulceration and infection rates were relatively low for this high-risk population. BTM may also offer promise as an alternative to free flaps.

Lay Summary

The prevalence of diabetes and its complications, including foot ulcers and wounds, have significantly increased worldwide over the last 40 years. Increasingly patients are admitted to hospital for antibiotics, debridements and subsequent amputations from these wounds. Complex diabetes-associated wounds are those at highest risk of these complications or necessitating more extensive, complex operations such as free flaps. These wounds may have exposed deep structures, be at risk of high shear stress or be chronic non-healing wounds.

Temporisers are a type of material which integrates into the wound and promotes in-growth of tissue, ideal for healing over these difficult to heal areas. Biodegradable Temporising Matrix (BTM) is a synthetic temporising matrix which has demonstrated positive outcomes in facilitating healing in burns and plastics wounds, but its effectiveness in diabetic foot wounds has not yet been proven. This is the first prospective cohort pilot study evaluating the use of BTM for complex diabetic foot wounds. BTM demonstrates potential in healing uninfected, non-ischaemic complex diabetic foot wounds and potentially avoiding more complex operations.

LRG1 destabilizes tumor vessels and restricts immunotherapeutic potency

BACKGROUND

A poorly functioning tumor vasculature is pro-oncogenic and may impede the delivery of therapeutics. Normalizing the vasculature, therefore, may be beneficial. We previously reported that the secreted glycoprotein leucine-rich α-2-glycoprotein 1 (LRG1) contributes to pathogenic neovascularization. Here, we investigate whether LRG1 in tumors is vasculopathic and whether its inhibition has therapeutic utility.

METHODS

Tumor growth and vascular structure were analyzed in subcutaneous and genetically engineered mouse models in wild-type and Lrg1 knockout mice. The effects of LRG1 antibody blockade as monotherapy, or in combination with co-therapies, on vascular function, tumor growth, and infiltrated lymphocytes were investigated.

FINDINGS

In mouse models of cancer, Lrg1 expression was induced in tumor endothelial cells, consistent with an increase in protein expression in human cancers. The expression of LRG1 affected tumor progression as Lrg1 gene deletion, or treatment with a LRG1 function-blocking antibody, inhibited tumor growth and improved survival. Inhibition of LRG1 increased endothelial cell pericyte coverage and improved vascular function, resulting in enhanced efficacy of cisplatin chemotherapy, adoptive T cell therapy, and immune checkpoint inhibition (anti-PD1) therapy. With immunotherapy, LRG1 inhibition led to a significant shift in the tumor microenvironment from being predominantly immune silent to immune active.

CONCLUSIONS

LRG1 drives vascular abnormalization, and its inhibition represents a novel and effective means of improving the efficacy of cancer therapeutics.

FUNDING

Wellcome Trust (206413/B/17/Z), UKRI/MRC (G1000466, MR/N006410/1, MC/PC/14118, and MR/L008742/1), BHF (PG/16/50/32182), Health and Care Research Wales (CA05), CRUK (C42412/A24416 and A17196), ERC (ColonCan 311301 and AngioMature 787181), and DFG (CRC1366).

The "Neuro-Glial-Vascular" Unit: The Role of Glia in Neurovascular Unit Formation and Dysfunction

The neurovascular unit (NVU) is a complex multi-cellular structure consisting of endothelial cells (ECs), neurons, glia, smooth muscle cells (SMCs), and pericytes. Each component is closely linked to each other, establishing a structural and functional unit, regulating central nervous system (CNS) blood flow and energy metabolism as well as forming the blood-brain barrier (BBB) and inner blood-retina barrier (BRB). As the name suggests, the “neuro” and “vascular” components of the NVU are well recognized and neurovascular coupling is the key function of the NVU. However, the NVU consists of multiple cell types and its functionality goes beyond the resulting neurovascular coupling, with cross-component links of signaling, metabolism, and homeostasis. Within the NVU, glia cells have gained increased attention and it is increasingly clear that they fulfill various multi-level functions in the NVU. Glial dysfunctions were shown to precede neuronal and vascular pathologies suggesting central roles for glia in NVU functionality and pathogenesis of disease. In this review, we take a “glio-centric” view on NVU development and function in the retina and brain, how these change in disease, and how advancing experimental techniques will help us address unanswered questions.

Temporal multi-omics identifies LRG1 as a vascular niche instructor of metastasis

Metastasis is the primary cause of cancer-related mortality. Tumor cell interactions with cells of the vessel wall are decisive and potentially rate-limiting for metastasis. The molecular nature of this cross-talk is, beyond candidate gene approaches, hitherto poorly understood. Using endothelial cell (EC) bulk and single-cell transcriptomics in combination with serum proteomics, we traced the evolution of the metastatic vascular niche in surgical models of lung metastasis. Temporal multiomics revealed that primary tumors systemically reprogram the body’s vascular endothelium to perturb homeostasis and to precondition the vascular niche for metastatic growth. The vasculature with its enormous surface thereby serves as amplifier of tumor-induced instructive signals. Comparative analysis of lung EC gene expression and secretome identified the transforming growth factor–β (TGFβ) pathway specifier LRG1, leucine-rich alpha-2-glycoprotein 1, as an early instructor of metastasis. In the presence of a primary tumor, ECs systemically up-regulated LRG1 in a signal transducer and activator of transcription 3 (STAT3)–dependent manner. A meta-analysis of retrospective clinical studies revealed a corresponding up-regulation of LRG1 concentrations in the serum of patients with cancer. Functionally, systemic up-regulation of LRG1 promoted metastasis in mice by increasing the number of prometastatic neural/glial antigen 2 (NG2)+ perivascular cells. In turn, genetic deletion of Lrg1 hampered growth of lung metastasis. Postsurgical adjuvant administration of an LRG1-neutralizing antibody delayed metastatic growth and increased overall survival. This study has established a systems map of early primary tumor-induced vascular changes and identified LRG1 as a therapeutic target for metastasis.

LRG1 Expression Is Elevated in the Eyes of Patients with Neovascular Age-Related Macular Degeneration

Leucine-rich a-2-glycoprotein 1 (LRG1) is a candidate therapeutic target for treating the neovascular form of age-related macular degeneration (nvAMD). In this study we examined the expression of LRG1 in eyes of nvAMD patients. Choroidal neovascular membranes (CNVMs) from patients who underwent submacular surgery for retinal pigment epithelium-choroid graft transplantation were collected from 5 nvAMD patients without any prior intravitreal anti-VEGF injection, and from six patients who received intravitreal anti-VEGF injections before surgery. As controls free of nvAMD, retina sections were obtained from the eyes resected from a patient with lacrimal sac tumor and from a patient with neuroblastoma. CNVMs were immunostained for CD34, LRG1, and α-smooth muscle actin (α-SMA). Aqueous humor samples were collected from 58 untreated-naïve nvAMD patients prior to the intravitreal injection of anti-VEGF and 51 age-matched cataract control patients, and LRG1 concentration was measured by ELISA. The level of LRG1 immunostaining is frequently high in both the endothelial cells of the blood vessels, and myofibroblasts in the surrounding tissue of CNVMs of treatment-naïve nvAMD patients. Furthermore, the average concentration of LRG1 was significantly higher in the aqueous humor of nvAMD patients than in controls. These observations provide a strong experimental basis and scientific rationale for the progression of a therapeutic anti-LRG1 monoclonal antibody into clinical trials with patients with nvAMD.

Leucine-rich alpha-2-glycoprotein 1 (LRG1) as a novel ADC target

Leucine-rich alpha-2-glycoprotein 1 (LRG1) is present abundantly in the microenvironment of many tumours where it contributes to vascular dysfunction, which impedes the delivery of therapeutics. In this work we demonstrate that LRG1 is predominantly a non-internalising protein. We report the development of a novel antibody-drug conjugate (ADC) comprising the anti-LRG1 hinge-stabilised IgG4 monoclonal antibody Magacizumab coupled to the anti-mitotic payload monomethyl auristatin E (MMAE) via a cleavable dipeptide linker using the site-selective disulfide rebridging dibromopyridazinedione (diBrPD) scaffold. It is demonstrated that this ADC retains binding post-modification, is stable in serum and effective in in vitro cell studies. We show that the extracellular LRG1-targeting ADC provides an increase in survival in vivo when compared against antibody alone and similar anti-tumour activity when compared against standard chemotherapy, but without undesired side-effects. LRG1 targeting through this ADC presents a novel and effective proof-of-concept en route to improving the efficacy of cancer therapeutics.

A chemisorbed interfacial layer for seeding atomic layer deposition on graphite

The integration of graphene, and more broadly two-dimensional materials, into devices and hybrid materials often requires the deposition of thin films on their usually inert surface. As a result, strategies for the introduction of surface reactive sites have been developed but currently pose a dilemma between robustness and preservation of the graphene properties. A method is reported here for covalently modifying graphitic surfaces, introducing functional groups that act as reactive sites for the growth of high quality dielectric layers. Aryl diazonium species containing tri-methoxy groups are covalently bonded (grafted) to highly oriented pyrolytic graphite (HOPG) and graphene, acting as seeding species for atomic layer deposition (ALD) of Al₂O₃, a high-κ dielectric material. A smooth and uniform dielectric film growth is confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrical measurements. Raman spectroscopy showed that the aryl groups gradually detach from the graphitic surface during the Al₂O₃ ALD process at 150 °C, with the surface reverting back to the original sp²-hybridized state and without damaging the dielectric layer. Thus, the grafted aryl groups can act as a sacrificial seeding layer after healing the defects of the graphitic surface with annealing treatment.

Thermodilution-derived temperature recovery time: a novel predictor of microvascular reperfusion and prognosis after myocardial infarction

BACKGROUND

Novel parameters that detect failed microvascular reperfusion might identify better the patients likely to benefit from adjunctive treatments during primary percutaneous coronary intervention (PCI).

AIMS

The aim of this study was to test the hypothesis that a novel invasive parameter, the thermodilution-derived temperature recovery time (TRT), would be associated with microvascular obstruction (MVO) and prognosis.

METHODS

TRT was derived and validated in two independent ST-elevation myocardial infarction populations and was measured immediately post PCI. TRT was defined as the duration (seconds) from the nadir of the hyperaemic thermodilution curve to 20% from baseline body temperature. MVO extent (% left ventricular mass) was assessed by cardiovascular magnetic resonance imaging at 2-7 days.

RESULTS

In the retrospective derivation cohort (n=271, mean age 60±12 years, 72% male), higher TRT was associated with more MVO (coefficient: 4.09 [95% CI: 2.70-5.48], p<0.001), independently of IMR >32, CFR ≤2, hyperaemic Tmn >median, thermodilution waveform, age and ischaemic time. At five years, higher TRT was multivariably associated with all-cause death/heart failure hospitalisation (OR 4.14 [95% CI: 2.08-8.25], p<0.001) and major adverse cardiac events (OR 4.05 [95% CI: 2.00-8.21], p<0.001). In the validation population (n=144, mean age 59±11 years, 80% male), the findings were confirmed prospectively.

CONCLUSIONS

TRT represents a novel diagnostic advance for predicting MVO and prognosis. ClinicalTrials.gov Identifiers: NCT02072850 & NCT02257294 Visual summary. Thermodilution-derived temperature recovery time (TRT): a novel predictor of microvascular reperfusion & prognosis after STEMI. CMR: cardiovascular magnetic resonance; MACE: major adverse cardiac events; MVO: microvascular obstruction; PCI: percutaneous coronary intervention; STEMI: ST-segment elevation myocardial infarction.

A 30-Year-Old Man With Primary Cardiac Angiosarcoma

A previously fit and well 30-year-old man presented with palpitations, fever, and pleuritic chest pain. Multimodality imaging and histopathology confirmed the diagnosis of primary cardiac angiosarcoma. We present the details of the presentation, diagnostic process using multimodality imaging, and clinical management. (Level of Difficulty: Beginner.)

Topographical Response of Retinal Neovascularization to Aflibercept or Panretinal Photocoagulation in Proliferative Diabetic Retinopathy: Post Hoc Analysis of the CLARITY Randomized Clinical Trial

Question

What is the topographic distribution of retinal neovascularization in patients with proliferative diabetic retinopathy, and is there an association between response to treatment and the retinal location of the neovascularization?

Findings

In this post hoc unmasked analysis of the Clinical Efficacy and Mechanistic Evaluation of Aflibercept for Proliferative Diabetic Retinopathy (CLARITY) randomized clinical trial, treatment-naive retinal neovascularization elsewhere (NVE) had a predilection for the nasal quadrant. By 52 weeks, the aflibercept group was more likely to have regression of NVE; neither treatment was likely to be associated with complete regression of disc neovascularization (NVD).

Meaning

This study further elaborates on the outcomes of the CLARITY trial in that, anatomically, despite the superior outcomes among patients within NVE who received aflibercept, regression was seen more in NVE than in NVD.

Importance

Eyes with proliferative diabetic retinopathy have a variable response to treatment with panretinal photocoagulation (PRP) or anti–vascular endothelial growth factor agents. The location of neovascularization (NV) is associated with outcomes (eg, patients with disc NV [NVD] have poorer visual prognosis than those with NV elsewhere [NVE]).

Objective

To investigate the distribution of NV in patients with proliferative diabetic retinopathy and the topographical response of NV to treatment with aflibercept or PRP.

Design, Setting, and Participants

This post hoc analysis of the phase 2b randomized clinical single-masked multicenter noninferiority Clinical Efficacy and Mechanistic Evaluation of Aflibercept for Proliferative Diabetic Retinopathy (CLARITY) trial was conducted from November 1, 2019, to September 1, 2020, among 120 treatment-naive patients with proliferative diabetic retinopathy to evaluate the topography of NVD and NVE in 4 quadrants of the retina on color fundus photography at baseline and at 12 and 52 weeks after treatment.

Exposures

In the CLARITY trial, patients were randomized to receive intravitreal aflibercept (2 mg/0.05 mL at baseline, 4 weeks, and 8 weeks, and as needed from 12 weeks onward) or PRP (completed in initial fractionated sessions and then on an as-needed basis when reviewed every 8 weeks).

Main Outcomes and Measures

Main outcomes were per-retinal quadrant frequencies of NV at baseline and frequencies of patterns of regression, recurrence, and new occurrence at 12-week and 52-week unmasked follow-up.

Results

The study included 120 treatment-naive patients (75 men; mean [SD] age, 54.8 [14.6] years) with proliferative diabetic retinopathy (there was a 1:1 ratio of eyes to patients). At baseline, NVD with or without NVE was observed in 42 eyes (35.0%), and NVE only was found in 78 eyes (65.0%); NVE had a predilection for the nasal quadrant (64 [53.3%]). Rates of regression with treatment were higher among eyes with NVE (89 of 102 [87.3%]) compared with eyes with NVD (23 of 43 [53.5%]) by 52 weeks, with NVD being more resistant to either treatment with higher rates of persistence than NVE (20 of 39 [51.3%] vs 29 of 100 [29.0%]). Considering NVE, the regression rate in the temporal quadrant was lowest (32 of 42 [76.2%]). Eyes treated with aflibercept showed higher rates of regression of NVE compared with those treated with PRP (50 of 52 [96.2%] vs 39 of 50 [78.0%]; difference, 18.2% [95% CI, 5.5%-30.8%]; P = .01), but no difference was found for NVD (11 of 17 [64.7%] vs 12 of 26 [46.2%]; difference, 18.6% [95% CI, −11.2% to 48.3%]; P = .23).

Conclusions and Relevance

This post hoc analysis found that NVD is less frequent but is associated with more resistance to currently available treatments than NVE. Aflibercept was superior to PRP for treating NVE, but neither treatment was particularly effective against NVD by 52 weeks. Future treatments are needed to better target NVD, which has poorer visual prognosis.

Trial Registration

isrctn.org Identifier: ISRCTN32207582

Small-molecule antagonist of VLA-4 (GW559090) attenuated neuro-inflammation by targeting Th17 cell trafficking across the blood-retinal barrier in experimental autoimmune uveitis

Background

The integrin VLA-4 (α4β1) plays an important role in leukocyte trafficking. This study investigated the efficacy of a novel topical α4β1 integrin inhibitor (GW559090, GW) in a mouse model for non-infectious posterior uveitis (experimental autoimmune uveitis; EAU) and its effect on intraocular leukocyte subsets.

Methods

Mice (female; B10.RIII or C57Bl/6; aged 6–8 weeks) were immunized with specific interphotoreceptor retinoid-binding protein (IRBP) peptides to induce EAU. Topically administered GW (3, 10, and 30 mg/ml) were given twice daily either therapeutically once disease was evident, or prophylactically, and compared with vehicle-treated (Veh) and 0.1% dexamethasone-treated (Dex) controls. Mice were sacrificed at peak disease. The retinal T cell subsets were investigated by immunohistochemistry and immunofluorescence staining. The immune cells within the retina, blood, and draining lymph nodes (dLNs) were phenotyped by flow cytometry. The effect of GW559090 on non-adherent, adherent, and migrated CD4⁺ T cell subsets across a central nervous system (CNS) endothelium was further assayed in vitro and quantitated by flow cytometry.

Results

There was a significant reduction in clinical and histological scores in GW₁₀- and Dex-treated groups as compared to controls either administered therapeutically or prophylactically. There were fewer CD45⁺ leukocytes infiltrating the retinae and vitreous fluids in the treated GW₁₀ group (P < 0.05). Immunofluorescence staining and flow cytometry data identified decreased levels of retinal Th17 cells (P ≤ 0.001) in the GW₁₀-treated eyes, leaving systemic T cell subsets unaffected. In addition, fewer Ly6C⁺ inflammatory monocyte/macrophages (P = 0.002) and dendritic cells (P = 0.017) crossed the BRB following GW₁₀ treatment. In vitro migration assays confirmed that Th17 cells were selectively suppressed by GW559090 in adhering to endothelial monolayers.

Conclusions

This α4β1 integrin inhibitor may exert a modulatory effect in EAU progression by selectively blocking Th17 cell migration across the blood-retinal barrier without affecting systemic CD4⁺ T cell subsets. Local α4β1 integrin-directed inhibition could be clinically relevant in treating a Th17-dominant form of uveitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02080-8.

UK national and regional trends in cardiovascular magnetic resonance usage – the British Society of CMR survey results

Background

CMR is an imaging modality recommended for multiple indications. Access to CMR is a key issue for its clinical use. We surveyed all CMR units in the UK.

Methods

An online survey of CMR units in the UK, with responses analysed by region and compared with population data.

Results

Response rate was 100% (Table). The UK performed a total of 102,886 scans in 2017, and 117,967 in 2018 representing a 1-year 14.7% increase and a 10-year increase of 573% compared to 2008 data (20,597).By head of population in 2018 there were 1,776 CMR scans per million people, with significant variation nationally and regionally, e.g. 4,256 per million in London vs. 396 per million in Wales (Figure). Mean number of scans per unit was 1,404, (range 98–10,000) with wide variation in referral to diagnostic times (mean 45.7 days, range 5–180) (Figure).

Clinical indications for CMR were: heart failure 21%, cardiomyopathy 27%, function and viability 22%, stress 24%, vascular disease 5%, valvular 5%, myocarditis/pericardial 10%, paediatric /congenital 10%, others e.g. transplant/masses 4%, with overlap. There were 358 consultants reporting CMR in 2018 (234 (65%) cardiologists and 124 (35%) radiologists). 81% of units had a CMR service for patients with pacemakers and defibrillators.

Conclusion

The survey shows the state of CMR in the UK. The 10-year growth has been remarkable, but there are wide disparities in terms of use, access and wait times with potential implications for clinical care. Action is needed to make access equitable across the UK.

Figure 1

Funding Acknowledgement

Type of funding source: None

Stratifying the prognostic capability of cardiovascular magnetic resonance in severe aortic stenosis: a machine learning approach

Background

Cardiovascular magnetic resonance (CMR) demonstrates promise in improving patient risk stratification in aortic stenosis (AS). We explored whether machine learning might provide further insights into the prognostic capability of CMR parameters.

Methods

Severe AS patients (n=440) undergoing AVR were prospectively enrolled across 10 international sites, and CMR performed prior to AVR. A machine learning prediction model using a random survival forest (RSF) was trained with 29 variables, including 13 CMR, 4 echocardiography, and 12 clinical parameters, using post-AVR mortality as an outcome. The impact of the important variables on the outcome (partial dependency) was examined.

Results

The most predictive CMR parameters in the RSF model were the extracellular volume fraction (ECV%), followed by right ventricular ejection fraction (RVEF), late gadolinium enhancement (LGE%), and indexed left ventricular end-diastolic volume (LVEDVi). Regarding the partial effects, the predicted mortality increased strongly once the ECV% exceeded 26.5% (Figure 1A). The LGE% was associated with an increased risk of mortality, which reached a plateau beyond the level of 2% (Figure 1C). There were U-shaped relationships between mortality and both RVEF and LVEDVi, with the lowest mortality seen at RVEF 70% and LVEDVi 68ml/m2 (Figure 1B, D). These trends of predicted outcomes by each variable were verified in the Kaplan-Meier curves and Cox analyses (Table). In both Cox and RSF models, the predictability was substantially increased when these four CMR parameters were added to conventional clinical risk factors. An AS-CMR risk score comprised of these four parameters presented a stepwise increase in mortality with increasing adverse CMR features (p&lt;0.001).

Conclusions

Our machine learning analysis using RSF has identified ECV%, RVEF, LGE%, and LVEDVi as key prognostic markers in severe AS with a nonlinear influence of each parameter on mortality post-AVR.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was supported by grants from the Korean Health Technology R & D Project, Ministry of Health, Welfare & Family Affairs, Republic of Korea (HI16C0225 and HI15C0399) and the National Institute for Health Research (NIHR) infrastructure at Leeds.

A Multifunctional Role of Leucine-Rich α-2-Glycoprotein 1 in Cutaneous Wound Healing Under Normal and Diabetic Conditions

Delayed wound healing is commonly associated with diabetes. It may lead to amputation and death if not treated in a timely fashion. Limited treatments are available partially due to the poor understanding of the complex disease pathophysiology. Here, we investigated the role of leucine-rich α-2-glycoprotein 1 (LRG1) in normal and diabetic wound healing. First, our data showed that LRG1 was significantly increased at the inflammation stage of murine wound healing, and bone marrow-derived cells served as a major source of LRG1. LRG1 deletion causes impaired immune cell infiltration, reepithelialization, and angiogenesis. As a consequence, there is a significant delay in wound closure. On the other hand, LRG1 was markedly induced in diabetic wounds in both humans and mice. LRG1-deficient mice were resistant to diabetes-induced delay in wound repair. We further demonstrated that this could be explained by the mitigation of increased neutrophil extracellular traps (NETs) in diabetic wounds. Mechanistically, LRG1 mediates NETosis in an Akt-dependent manner through TGFβ type I receptor kinase ALK5. Taken together, our studies demonstrated that LRG1 derived from bone marrow cells is required for normal wound healing, revealing a physiological role for this glycoprotein, but that excess LRG1 expression in diabetes is pathogenic and contributes to chronic wound formation.

Evaluation of real-world early response of DMO to aflibercept therapy to inform future clinical trial design of novel investigational agents

New clinical trials for diabetic macular oedema (DMO) are being designed to prove superiority over aflibercept when this agent is already very effective in improving visual acuity (VA) and DMO. The aim of this study was to determine the optimal inclusion–exclusion criteria for trials to aim for superiority in visual outcomes with newer agents. As Phase 1 studies are short duration, we aimed to evaluate the early response of aflibercept in a real-world cohort initiated on monthly aflibercept for 3 consecutive injections and observed the effects at 4 months. The sub-optimal responders were pre-defined based on different cut-offs for VA and central sub-field thickness (CST). 200 patients with treatment naïve DMO treated with 3 loading doses of aflibercept were included in the study. We found that those presenting with baseline VA of 35–54 ETDRS letters (n = 43) had higher proportion of sub-optimal responders compared to other categories (p < 0.001). Patients with baseline CST of less than 400 µm (n = 96) responded less well functionally and anatomically to loading dose than eyes with baseline CST of 400 µm or more (n = 104, p = 0.02), indicating that eyes with CST ≥ 400 µm is another inclusion criteria. There was minimal correlation between change in CST and change in VA at 4 months (r = − 0.27), suggesting that both these inclusion criteria are non-exclusive. However, for maximal efficacy, patients that meet both these inclusion criteria are more likely to show benefit from an alternative intervention. New trials should aim to include patients with treatment naïve DMO with VA between 35–54 letters and CST of 400 µm or more when aflibercept is used as the comparator.

Functional Evaluation of AMD-Associated Risk Variants of Complement Factor B

Purpose

The 32W and 32Q variants of complement factor B (CFB) are associated with reduced risk of developing neovascular age-related macular degeneration (AMD) compared with the common 32R allele. The objective of this study was to determine if the most protective R32Q variant affects the neovascular process in a manner consistent with the reported reduced disease association.

Methods

The 32R, 32W, and 32Q human CFB variants were expressed in human embryonic kidney 293T cells and purified from culture supernatant. The ex vivo mouse fetal metatarsal explant model was used to investigate the effect of these three human CFB variants on angiogenesis. Metatarsal bones were isolated from mouse embryos and cultured in the presence of the three CFB variants, and angiogenesis was measured following immunostaining of fixed samples. ELISAs were used to quantify C3 and VEGF protein levels in metatarsal culture and quantitative PCR to measure Cfb, C3, and Vegf expression.

Results

We show here that the three CFB variants have different biological activities in the mouse metatarsal assay, with CFBR32 exhibiting significantly greater angiogenic activity than CFBQ32 or CFBW32, which were broadly similar. We also observed differences in macrophage phenotype with these two variants that may contribute to their activities in this experimental model.

Conclusions

We have demonstrated that the biological activities of CFBR32, CFBW32, and CFBQ32 are consistent with their AMD risk association, and we provide functional evidence of roles for these variants in angiogenesis that may be relevant to the pathogenesis of the neovascular form of AMD.

Nutrition and Gastrointestinal Dysmotility in Critically Ill Burn Patients: A Retrospective Observational Study

BACKGROUND

Gastrointestinal (GI) dysmotility impedes nutrient delivery in critically ill patients with major burns. We aimed to quantify the incidence, timing, and factors associated with GI dysmotility and subsequent nutrition delivery.

METHODS

A 10-year retrospective observational study included mechanically ventilated, adult, critically ill patients with ≥15% total body surface area (TBSA) burns receiving nutrition support. Patients with a single gastric residual volume ≥250 mL were categorized as having GI dysmotility. Daily medical and nutrition data were extracted for ≤14 days in the intensive care unit (ICU). Data are mean (SD) or median (interquartile range). Factors associated with GI dysmotility and the effect on nutrition and clinical outcomes were assessed.

RESULTS

Fifty-nine patients were eligible; 51% (n = 30) with GI dysmotility and 49% (n = 29) without. Baseline characteristics (dysmotility vs no dysmotility) were age (48 [33-60] vs 34 [26-46] years); Acute Physiology and Chronic Health Evaluation II score (16 [12-17] vs 13 [10-16]); sex ([men] 80% vs 86%); and TBSA (49% [35%-59%] vs 38% [26%-55%]). Older age was associated with increased probability of dysmotility (P = .049). GI dysmotility occurred 32 (19-63) hours after ICU admission but was not associated with reduced nutrient delivery. Postpyloric tube insertions were attempted in 83% (n = 25) of patients, with 72% (n = 18) being successful. Postpyloric feeding achieved higher nutrition adequacy than gastric feeding (energy: 82% [95% CI, 70-94] vs 68% [95% CI, 63-74], P = .036; protein: 75% [95% CI, 65-86] vs 61% [95% CI, 56-65], P = .009).

CONCLUSION

GI dysmotility occurs early in critically ill burn patients, and postpyloric feeding improves nutrition delivery.

Abstract 1477: LRG1 blockade normalizes tumor vasculature and improves efficacy of chemotherapy

In cancer blood vessels are dysfunctional, poorly perfused and leaky. Malfunctioning vessels contribute to the pro-oncogenic environment and limit the efficacy of current systemically administered drugs. Normalizing the tumor vasculature to improve vessel permeability, reduce hypoxia and vascular leakage and enhance drug delivery, has become an experimental objective in cancer research. This study was carried out to investigate the effect of blocking the secreted glycoprotein leucine-rich alpha-2-glycoprotein 1 (LRG1) on tumor vascular function, and evaluate the impact it has on the efficacy of the common standard of care chemotherapeutic drug cisplatin. Under normal conditions LRG1 is mainly expressed in the liver but also in other tissues such as bone marrow and immune cells. LRG1 has been described in multiple reports to be a serum prognostic biomarker in several cancers, for example lung, prostate, colorectal and breast. LRG1 promotes dysfunctional vessel growth by disrupting TGFβ signaling. We demonstrate that in Lrg1-/- mice and following treatment with a LRG1 function-blocking antibody (15C4) tumor growth was inhibited. In addition, we show using RNAscope that following subcutaneous grafting of the B16F0 and LL2 tumor cell lines in mice, Lrg1 is induced in tumor endothelial cells. Despite having no effect on total vessel area, the density was decreased upon LRG1 blockade, with the persisting larger vessels exhibiting improved vessel structure as evidenced by increased pericyte and basement membrane endothelial cell coverage. Better mural cell association with tumor vascular endothelial cells and basement membrane coverage are also indicators of vessel stabilization and maturation. Using a systemically delivered fluorescent lectin tracer to mark perfused vessels, we observed a significant increase in tumor perfusion in mice treated with 15C4. Lastly, vessel normalization, through LRG1 antibody blockade, significantly enhanced the efficacy of cisplatin chemotherapy as shown by a slower tumor growth rate and increased tumor cell death compared to monotherapy. These data further corroborate the hypothesis that inhibition of LRG1 improves the delivery, and hence efficacy, of a cytotoxic drug. In conclusion, deletion or inhibition of LRG1 results in an improved vascular configuration and function, and the efficacy of chemotherapy. LRG1 blockade may therefore represent a novel strategy to enhance vessel health and improve the efficacy of cancer therapeutics.

Citation Format: Camilla Pilotti, Marie N O'Connor, David Kallenberg, Laura Dowsett, Jestin George, Stephen E. Moss, John Greenwood. LRG1 blockade normalizes tumor vasculature and improves efficacy of chemotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1477.

THU0342 DECLINE IN SUBCLINICAL SYSTEMIC SCLEROSIS PRIMARY HEART INVOLVEMENT ASSOCIATES WITH POOR PROGNOSTIC FACTORS AND ACTIVE INTERSTITIAL LUNG DISEASE

Background:

Primary systemic sclerosis heart involvement (pSSc-HI) is described in the majority of SSc patients when sensitive methods such as cardiovascular magnetic resonance (CMR) are used1. The natural history of these subclinical findings are unknown.

Objectives:

To evaluate for interval change in subclinical pSSc-HI, the association between change in CMR abnormalities and disease phenotype and whether disease modifying antirheumatic (DMARD) and/or vasodilator treatment influence the CMR course.

Methods:

SSc patients, fulfilling the 2013 ACR/EULAR criteria, with no cardiovascular (CV) disease, diabetes and no more than 2 CV risk factors had two CMRs performed (V1 & V2; minimum 1 year apart). A 3T CMR with late gadolinium enhancement (LGE), T1 mapping for extracellular volume (ECV of diffuse fibrosis) quantification and stress perfusion was undertaken.

Results:

31 SSc patients were evaluated, with median (IQR) follow up (between the 2 CMR scans) of 33 (17, 37) months. Median (IQR) age was 52 (47,60), 32% had diffuse cutaneous SSc, 52% interstitial lung disease (ILD), 29% Scl70+.

4/31 patients had a non-ischaemic LGE pattern suggesting focal fibrosis at V1, with no change in the pattern, distribution, or median (IQR) LGE scar mass between V1 and V2 [1.88 (1.01, 6.34) vs 1.70 (1.21, 4.18)]. At V2, 2 additional patients showed focal fibrosis, of which one had an episode of clinically diagnosed myocarditis. No significant change in ECV, T1 native, myocardial perfusion reserve (MPR) or left ventricle (LV) volumes and function were noted at V2 compared with V1 (p>0.01).

SSc patients with either increase in pre-existing LGE scar mass (n=1) or new fibrosis were all dcSSc, with ILD, 2 Scl70+. A reduction in forced vital capacity and total lung capacity associated with a reduction in LV ejection fraction (LVEF) (rho=0.413, p=0.021; rho-0.335, p=0.07) and MPR (rho=0.543, p=0.007; rho=0.627, p=0.002).

Patients receiving DMARD treatment had higher baseline LV end-diastolic volume compared to those with no DMARD treatment [mean (SD) 78 (19) vs 69 (10), p=0.167]. A decrease in LV stroke volume and an increase in T1 native at V1 vs V2 was noted for those on DMARD [mean (SD) 49 (8) vs 46 (8), p =0.023; 1208 (65) vs 1265 (56), p=0.008 respectively] (Figure 1). No significant change in CMR measures in those receiving vasodilator or angiotensin-converting-enzyme inhibitor treatment was noted (p>0.01).

Figure 1.

Mean (SD) of T1 native, LVSV/BSA, LVEF, and LVEDV/BSA at V1 compared to V2 in those with and without DMARD treatment. BSA, body surface area; DMARD, disease modifying antirheumatic drugs; EDV, end-diastolic volume; SV, stroke volume; LV left ventricular; EF, ejection fraction.

Conclusion:

This first, pilot longitudinal study of CMR-defined subclinical pSSc-HI suggests largely stable appearances with follow-up. Progression of new focal fibrosis and decline in LV function and MPR, where observed, associated with poor prognostic factors of SSc and ILD progression. Consistent with this, individuals on DMARD appeared to show interval decline. Larger longitudinal studies are warranted to confirm these findings and inform on utility of CMR monitoring of subclinical pSSc-HI in poor prognosis SSc.

References:

[1]Ntusi NA et al, J Cardiovasc Magn Reson. 2014

Disclosure of Interests:

Raluca-Bianca Dumitru: None declared, Lesley Anne Bissell: None declared, Bara Erhayiem: None declared, Graham Fent: None declared, Ananth Kidambi: None declared, Giuseppina Abignano: None declared, John Greenwood: None declared, John Biglands: None declared, Francesco Del Galdo: None declared, Sven Plein: None declared, Maya H Buch Grant/research support from: Pfizer, Roche, and UCB, Consultant of: Pfizer; AbbVie; Eli Lilly; Gilead Sciences, Inc.; Merck-Serono; Sandoz; and Sanofi

The ORNATE India Project: United Kingdom-India Research Collaboration to tackle visual impairment due to diabetic retinopathy

INTRODUCTION

The ORNATE India project is funded by the UK Research and Innovation (UKRI) through the Global Challenges Research Fund. The aim is to build research capacity and capability in India and the UK to tackle global burden of diabetes-related visual impairment. As there are over 77 million people with diabetes in India, it is challenging to screen every person with diabetes annually for sight-threatening diabetic retinopathy (DR). Therefore, alternate safe approaches need to be developed so that those at-risk of visual impairment due to DR is identified promptly and treated.

METHODS

The project team utilised diverse global health strategies and research methods to co-design work packages to build research capacity and capability to ensure effective, affordable and efficient DR services are made available for the population. The strategies and methods employed included health system strengthening; implementation science; establishing care pathways; co-designing collaborative studies on affordable technologies, developing quality standards and guidelines to decrease variations in care; economic analysis; risk modelling and stratification. Five integrated work packages have been developed to deal with all aspects of DR care. These included implementation of a DR screening programme in the public health system in a district in Kerala, evaluating regional prevalence of diabetes and DR and assessing ideal tests for holistic screening for diabetes and its complications in 20 areas in India, utilising artificial intelligence on retinal images to facilitate DR screening, exploring biomarker and biosensor research to detect people at risk of diabetes complications, estimating cost of blindness in India and risk modelling to develop risk-based screening models for diabetes and its complications. A large collaborative network will be formed to propagate research, promote shared learning and bilateral exchanges between high- and middle-income countries to tackle diabetes-related blindness.

Annexin A8 regulates Wnt signaling to maintain the phenotypic plasticity of retinal pigment epithelial cells

Wnt signalling mediates complex cell-cellinteractions during development and proliferation. Annexin A8 (AnxA8), a calcium-dependent phospholipid-binding protein, and canonical Wnt signalling mechanisms have both been implicated in retinal pigment epithelial (RPE) cell differentiation. The aim here was to examine the possibility of cross-talk between AnxA8 and Wnt signalling, as both are down-regulated upon fenretinide (FR)-mediated RPE transdifferentiation. AnxA8 suppression in RPE cells via siRNA or administration of FR induced neuronal-like cell transdifferentiation and reduced expression of Wnt-related genes, as measured by real-time PCR and western blotting. AnxA8 gene expression, on the other hand, remained unaltered upon manipulating Wnt signalling, suggesting Wnt-related genes to be downstream effectors of AnxA8. Co-immunoprecipitation revealed an interaction between AnxA8 and β-catenin, which was reduced in the presence of activated TGF-β1. TGF-β1 signalling also reversed the AnxA8 loss-induced cell morphology changes, and induced β-catenin translocation and GSK-3β phosphorylation in the absence of AnxA8. Ectopic over-expression of AnxA8 led to an increase in active β-catenin and GSK-3β phosphorylation. These data demonstrate an important role for AnxA8 as a regulator of Wnt signalling and a determinant of RPE phenotype, with implications for regenerative medicine approaches that utilise stem cell-derived RPE cells to treat conditions such as age-related macular degeneration.

P2707Invasive coronary physiology during primary percutaneous coronary intervention in patients treated with intracoronary alteplase or placebo: the double-blind T-TIME physiology substudy

Background

Impaired microcirculatory reperfusion worsens prognosis post-primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). Intracoronary (IC) alteplase targets persisting thrombus post-reperfusion & distal embolisation. In the T-TIME trial microvascular obstruction on cardiac magnetic resonance (CMR) did not differ with IC alteplase vs placebo.

Purpose

To prospectively determine if index of microcirculatory resistance (IMR) is lower & coronary flow reserve (CFR) or resistive reserve ratio (RRR) are higher (improved) with IC alteplase, & to provide mechanistic insights.

Methods

A pre-planned substudy of the main protocol. From 2016–2017, STEMI patients from 3 UK hospitals ≤6 hrs ischaemic time were randomised in a 1:1:1 dose-ranging, double-blind design. Following standard care reperfusion, alteplase (10 or 20mg) or placebo was infused over 5–10 mins proximal to the culprit lesion pre-stenting. IMR (primary outcome), CFR & RRR (secondary outcomes) were measured in the culprit artery post-PCI. Physiology results were obscured from clinicians acquiring the data, to maintain blinding. CMR was performed 2 days & 3 months post-STEMI. Subgroup analyses were prespecified including by ischaemic time (<2 hours, 2–4 hrs, >4 hrs) & IMR threshold >32.

Results

In 144 patients (mean age 59 yrs, 80% male), IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo (Table). Patients with ischaemic time <2 hrs had a dose related increase in CFR (placebo 1.2 [IQR 1.1–1.7], alteplase 10mg 1.4 [IQR 1.0–1.8], alteplase 20mg 2.0 [IQR 1.8–2.3] p=0.01 for interaction) & RRR (placebo 1.5 [IQR 1.3–1.9], alteplase 10mg 1.6 [1.1–2.2], alteplase 20mg 2.2 [2.0–2.6], p=0.03 for interaction). In subjects with post-PCI IMR>32, % ST-resolution at 60 mins was worse with alteplase 10mg vs placebo (23.1±53.9 vs 50.9±31.5) & in those with IMR≤32% ST-resolution at 60 mins was better with alteplase 20mg vs placebo (68.0±30.7 vs 39.1±43.2), p=0.002 for interaction. The CMR findings in the substudy & overall trial populations were consistent.

Main results Placebo Alteplase 10mg Alteplase 20mg (n=53) (n=41) (n=50) IMR, median (IQR) 33.0 (17.0–57.0) 22.0 (17.0–42.0) 37.0 (20.0–57.8) p=0.15 p=0.78 CFR, median (IQR) 1.3 (1.1–1.8) 1.4 (1.1–1.9) 1.5 (1.1–2.0) p=0.92 p=0.74 RRR, median (IQR) 1.6 (1.3–2.2) 1.6 (1.4–2.6) 1.8 (1.3–2.4) p=0.69 p=0.81 P-values for comparison of alteplase with placebo.

Conclusions

In acute STEMI with ischaemic time ≤6 hrs, IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo. In those with shorter ischaemic times (<2 hrs) CFR & RRR, but not IMR, were improved with alteplase. We observed interactions between alteplase dose, ischaemic time & mechanisms of effect.

Acknowledgement/Funding

Dr Maznyczka is funded by a fellowship from the British Heart Foundation (FS/16/74/32573). T-TIME was funded by grant 12/170/4 from NIHR-EME

A Multicenter, Scan-Rescan, Human and Machine Learning CMR Study to Test Generalizability and Precision in Imaging Biomarker Analysis

BACKGROUND

Automated analysis of cardiac structure and function using machine learning (ML) has great potential, but is currently hindered by poor generalizability. Comparison is traditionally against clinicians as a reference, ignoring inherent human inter- and intraobserver error, and ensuring that ML cannot demonstrate superiority. Measuring precision (scan:rescan reproducibility) addresses this. We compared precision of ML and humans using a multicenter, multi-disease, scan:rescan cardiovascular magnetic resonance data set.

METHODS

One hundred ten patients (5 disease categories, 5 institutions, 2 scanner manufacturers, and 2 field strengths) underwent scan:rescan cardiovascular magnetic resonance (96% within one week). After identification of the most precise human technique, left ventricular chamber volumes, mass, and ejection fraction were measured by an expert, a trained junior clinician, and a fully automated convolutional neural network trained on 599 independent multicenter disease cases. Scan:rescan coefficient of variation and 1000 bootstrapped 95% CIs were calculated and compared using mixed linear effects models.

RESULTS

Clinicians can be confident in detecting a 9% change in left ventricular ejection fraction, with greater than half of coefficient of variation attributable to intraobserver variation. Expert, trained junior, and automated scan:rescan precision were similar (for left ventricular ejection fraction, coefficient of variation 6.1 [5.2%-7.1%], P=0.2581; 8.3 [5.6%-10.3%], P=0.3653; 8.8 [6.1%-11.1%], P=0.8620). Automated analysis was 186× faster than humans (0.07 versus 13 minutes).

CONCLUSIONS

Automated ML analysis is faster with similar precision to the most precise human techniques, even when challenged with real-world scan:rescan data. Assessment of multicenter, multi-vendor, multi-field strength scan:rescan data (available at www.thevolumesresource.com) permits a generalizable assessment of ML precision and may facilitate direct translation of ML to clinical practice.