Glyco-engineered MDCK cells display preferred receptors of H3N2 influenza absent in eggs used for vaccines

Evolution of human H3N2 influenza viruses driven by immune selection has narrowed the receptor specificity of the hemagglutinin (HA) to a restricted subset of human-type (Neu5Acα2-6 Gal) glycan receptors that have extended poly-LacNAc (Galβ1-4GlcNAc) repeats. This altered specificity has presented challenges for hemagglutination assays, growth in laboratory hosts, and vaccine production in eggs. To assess the impact of extended glycan receptors on virus binding, infection, and growth, we have engineered N-glycan extended (NExt) cell lines by overexpressing β3-Ν-acetylglucosaminyltransferase 2 in MDCK, SIAT, and hCK cell lines. Of these, SIAT-NExt cells exhibit markedly increased binding of H3 HAs and susceptibility to infection by recent H3N2 virus strains, but without impacting final virus titers. Glycome analysis of these cell lines and allantoic and amniotic egg membranes provide insights into the importance of extended glycan receptors for growth of recent H3N2 viruses and relevance to their production for cell- and egg-based vaccines.

Hypoxia Controls the Glycome Signature and Galectin-8-Ligand Axis to Promote Protumorigenic Properties of Metastatic Melanoma

The prognosis for patients with metastatic melanoma (MM) involving distant organs is grim, and treatment resistance is potentiated by tumor-initiating cells (TICs) that thrive under hypoxia. MM cells, including TICs, express a unique glycome featuring i-linear poly-N-acetyllactosamines through the loss of I-branching enzyme, β1,6 N-acetylglucosaminyltransferase 2. Whether hypoxia instructs MM TIC development by modulating the glycome signature remains unknown. In this study, we explored hypoxia-dependent alterations in MM glycome‒associated genes and found that β1,6 N-acetylglucosaminyltransferase 2 was downregulated and a galectin (Gal)-8-ligand axis, involving both extracellular and cell-intrinsic Gal-8, was induced. Low β1,6 N-acetylglucosaminyltransferase 2 levels correlated with poor patient outcomes, and patient serum samples were elevated for Gal-8. Depressed β1,6 N-acetylglucosaminyltransferase 2 in MM cells upregulated TIC marker, NGFR/CD271, whereas loss of MM cell‒intrinsic Gal-8 markedly lowered NGFR and reduced TIC activity in vivo. Extracellular Gal-8 bound preferentially to i-linear poly-N-acetyllactosamines on N-glycans of the TIC marker and prometastatic molecule CD44, among other receptors, and activated prosurvival factor protein kinase B. This study reveals the importance of hypoxia governing the MM glycome by enforcing i-linear poly-N-acetyllactosamine and Gal-8 expression. This mechanistic investigation also uncovers glycome-dependent regulation of pro-MM factor, NGFR, implicating i-linear poly-N-acetyllactosamine and Gal-8 as biomarkers and therapeutic targets of MM.

Time-related aortic inflammatory response, as assessed with 18F-FDG PET/CT, in patients hospitalized with severely or critical COVID-19

Aim

Arterial involvement has been implicated in the coronavirus disease of 2019 (COVID-19). Fluorine 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging is a valuable tool for the assessment of aortic inflammation and is a predictor of outcome. We sought to prospectively assess the presence of aortic inflammation and its time-dependent trend in patients with COVID-19.

Methods

Between November 2020 and May 2021, in this pilot, case-control study, we recruited 20 patients with severe or critical COVID-19 (mean age of 59±12 years), while 10 age and sex-matched individuals served as the control group. Aortic inflammation was assessed by measuring 18F-FDG uptake in PET/CT performed 20–120 days post-admission. Global aortic target to background ratio (GLA-TBR) was calculated as the sum of TBRs of ascending and descending aorta, aortic arch, and abdominal aorta divided by 4. Index aortic segment TBR (IAS-TBR) was designated as the aortic segment with the highest TBR.

Results

There was no significant difference in aortic 18F-FDG PET/CT uptake between patients and controls (GLA-TBR: 1.46 [1.40–1.57] vs. 1.43 [1.32–1.70], respectively, p=0.422 and IAS-TBR: 1.60 [1.50–1.67] vs. 1.50 [1.42–1.61], respectively, p=0.155). There was a moderate correlation between aortic TBR values (both GLA and IAS) and time distance from admission to 18F-FDG PET-CT scan (Spearman's rho=−0.528, p=0.017 and Spearman's rho=−0.480, p=0.032, respectively), Figure 1. Patients who were scanned less than or equal to 60 days from admission (n=11) had significantly higher GLA-TBR values compared to patients that were examined more than 60 days post-admission (GLA-TBR: 1.53 [1.42–1.60] vs. 1.40 [1.33–1.45], respectively, p=0.016 and IAS-TBR: 1.64 [1.51–1.74] vs. 1.52 [1.46–1.60], respectively, p=0.038). There was a significant difference in IAS-TBR between patients scanned ≤60 days and controls (1.64 [1.51–1.74] vs. 1.50 [1.41–1.61], p=0.036), Figure 2.

Conclusion

This is the first study suggesting that aortic inflammation, as assessed by 18F-FDG PET/CT imaging, is increased in the early post-COVID phase in patients with severe or critical COVID-19 and largely resolves over time. Our findings may have important implications for the understanding of the course of the disease and for improving our preventive and therapeutic strategies.

Funding Acknowledgement

Type of funding sources: None.

Adipose tissue derived ceramides regulate myocardial redox state and predict cardiovascular outcomes

Background

Obesity is linked to both dysfunctional adipose tissue (AT) and heart failure, but the exact mechanisms mediating these associations are unknown. Although ceramides biosynthesis is dysregulated in obesity, their role as mediators of obesity-induced myocardial dysfunction is unclear.

Purpose

We investigate the causal role of AT-derived ceramides in the regulation of myocardial redox state and explore their role in predicting cardiovascular outcomes.

Methods

The study population included a total of 880 patients undergoing cardiac surgery. A panel of 20 sphingolipids was measured in plasma as well as in biopsies of subcutaneous AT (ScAT), thoracic AT (ThAT) and epicardial AT (EpAT) and their secretome, obtained from a subgroup of n=48. Myocardial redox state was measured using lucigenin chemiluminescence and the contribution of NOXs, uncoupled nitric oxide synthases and mitochondrial oxidases in O2•– production was quantified. The cohort was followed up for a median of 8.3 years. Genome-wide genetic analysis was done using the UK Biobank array. A total of 99,524 SNPs within 50kb of 110 genes involved in sphingolipid biosynthesis were analysed to identify genetic variants that could predict CVD outcomes using cis-Mendelian Randomisation. The underlying mechanisms were then explored further, using differentiated H9c2 cardiomyocytes in vitro and human right atrial tissue ex vivo.

Results

The production and secretion of C16:0-ceramide (CerC16) was higher in visceral AT (EpAT and ThAT) compared to ScAT (p<0.0001). Patients with high plasma levels of CerC16 and its derivative C16:0-glucosylceramide (GlcC16) had higher myocardial O2•– production vs those with low/int. levels (p<0.05 for both) (A). To test the causality of this association, we performed a targeted single-SNP analysis for the genetic prediction of GlcC16 levels demonstrating that rs112572487, an intronic variant in UGCG (an enzyme that catalyses glucosylceramide formation from ceramides), was the top hit (B). Indeed, those with the rs112572487 minor allele (G) displayed significantly increased myocardial NOX-derived O2•– (C) and plasma GlcC16 levels (D) vs those without. Exogenous CerC16 (20nM) induced NOX-derived O2•– production in H9c2 cardiomyocytes, an effect prevented by the UGCG inhibitor D-PDMP (E), suggesting that GlcC16 is a modifiable regulator of myocardial NOX-O2•–. Importantly, high plasma GlcC16 levels were associated with a higher risk of cardiac death and/or heart failure (adj. HR=2.128 [95% CI: 1.101, 4.115], p=0.025, for high vs low/int. levels), a relationship also seen with rs112572487 (F).

Conclusions

We demonstrate for the first time, that AT-derived ceramides are causally related with dysregulated myocardial redox signalling and adverse cardiovascular disease outcomes in patients with advanced atherosclerosis. As such, GlcC16 may be an important therapeutic target for the prevention and treatment of cardiovascular complications in obesity and diabetes.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The British Heart FoundationBritish Heart Foundation Chair Award

Distinctive characteristics among MINOCA and Takotsubo patients and their prognostic value in a multicenter prospective cohort

Background/Introduction

In the acute care setting, the working diagnosis of MINOCA exhibits increasing recognition and includes a broad spectrum of conditions, most of them yet not adequately understood. TakoTsubo syndrome (TTS) represents a significant proportion of such cases and despite its predominance on female gender as well as its imaging characteristics on the typical apical form it is not easily distinguishable from other MINOCA causes without the contribution of cardiac magnetic resonance (CMR).

Purpose

The aim of our study is to investigate for distinctive characteristics related to the index event among MINOCA cases from a multi-center prospective cohort with a mean follow up period of 18 months.

Methods

We divided our study population (n=74) into TTS (n=30) and non-TTS (n=44) according to multimodality imaging results. Information regarding the index event (Sep 2019-Feb 2021) were retracted from the medical notes.

Results

CMR results led to a post-discharge diagnosis reconsideration in 12 cases (16.2%). Female gender (n=29; 96.7% vs n=22; 50%, P<0.001), older age (mean age 66±11 vs 59±11, P=0.04) and history of hypertension (n=21; 70% vs n=19; 44.3%, p=0.035) were more frequent in TTS group. There was no statistically significant difference in body mass index, baseline renal function, history of dyslipidemia, diabetes and smoking between the two groups. During the index event, peak troponin levels 576 pg/ml (IQR: 184–9915) vs 767 pg/ml (IQR: 47–47000), P=0.005], were lower in the TTS group, whereas NSTEMI presentation was the commonest among all patients. Angina was the dominant symptom for both groups. However, severe angina expressed as more than 2 episodes within 24 hours was more frequent among the TTS population (n=19; 65.5% vs n=10; 22.7%, P=0.001). TTS probability assessed with the INTERTAK score was higher among the TTS group (68±10 vs 38±21, P<0.001). In hospital major cardiovascular events incidence was higher in the non-TTS group (n=2 vs n=11, P=0.06). Multivariate analysis revealed that the presence of severe angina (OR, 8.118, 95% CI: 1.173–56.157, P=0.038) is highly predictive of TTS in the acute care setting even independently of INTERTAK probability.

Conclusions

These preliminary results indicate that the presence of several anginal attacks may strengthen the predictive value of the INTERTAK score during MINOCA evaluation in the acute setting. Confirmation in a larger population is warranted.

Funding Acknowledgement

Type of funding sources: None.

Spontaneous coronary artery dissection: current evidence from cardiac magnetic resonance and angiography screening

Purpose

To assess the distribution and extent of myocardial infarction, as well as possible clinical significance of peripheral arteriopathy screening in a cohort of patients presented with spontaneous coronary dissection (SCAD) using cardiovascular magnetic resonance (CMR) for cardiac and vascular imaging. The adverse CMR features and predictors of infarction in subgroup analysis were also investigated.

Methods

This is an observational, single centre study of 144 consecutive, angiographically confirmed SCAD survivors >18 years old, based on collected data from Jan 2008-Nov 2020. All scans were performed on a 1.5-Tesla scanner. Cardiac structural and functional indices, myocardial infarct size and distribution were evaluated. In addition, vascular imaging was performed in all patients for thoracic aorta screening as part of the routine protocol, and in 75 patients peripheral arteriopathy screening from Circle of Willis to the iliac arteries was performed using 2D multi-slice and cine imaging, as well as 3D imaging methods.

Results

In the total population, 64% had infarction. Infarct size (%) was predictive of reduced left ventricular ejection fraction (LVEF) (p<0.001) and increased diastolic volumes (p<0.001 for both). Logistic regression showed SCAD in right coronary artery (Odds Ratio (OR): 5.2, p=0.034) predicted the presence of infarction. In the group who also underwent peripheral vascular screening, the overall prevalence of extra-coronary arteriopathy was 27% with fibromuscular dysplasia accounting for one-fourth of the cases (Figure 1). Of note, most positive vascular screening patients (73.3%) exhibited infarction (OR: 7.0, p=0.041), distributed in more than one territory (OR: 4.0, p=0.015) (Figure 2), while infarct size was negatively correlated with LVEF (p<0.001). Right ventricular ejection fraction was significantly reduced in positive screening patients (58.8±7.4 vs. 63.0±8.0, p=0.045). Further subgroup analysis showed pregnancy associated SCAD patients had significantly larger sized infarcts (25.1±6.1 vs. 6.2±0.7%, p<0.001) with reduced LVEF (51.0 vs 63.6±7.6, p<0.001). In logistic regression, this condition also predicted large infarcts >10% (OR: 9.8, p=0.009) in anterior walls (p<0.001).

Conclusions

Patients with SCAD require careful assessment of myocardial structure, function and characterization of infarction which may reflect the underlying pathophysiology. Extra coronary vascular screening, although not established in clinical practice, seems a rational strategy to potentially identify a subgroup with more severe infarction and likely to have vascular pathology.

Funding Acknowledgement

Type of funding sources: None.

Radiomics-based analysis by machine learning techniques improves characterization of functionally significant coronary lesions

Background

Computed Tomography Coronary Angiography (CTCA) is an effective non-invasive imaging modality for anatomo-functional assessment of coronary artery disease (CAD). Radiomics features have been used for diagnosis or outcome prediction, however, their potential value for characterizing flow limiting coronary lesions has not been explored.

Purpose

To assess whether application of novel radiomics and machine learning (ML) techniques on CTCA derived datasets improves characterization of functionally significant coronary lesions.

Methods

Consecutive patients with stable chest pain and intermediate pre-test likelihood for CAD, who underwent CTCA and PET-or SPECT-Myocardial Perfusion Imaging (MPI) respectively, were prospectively evaluated and included in the analysis. PET-MPI was considered abnormal when >1 contiguous segments showed both stress Myocardial Blood Flow ≤2.3mL/g/min and Myocardial Flow Reserve (MFR) ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively. Defect reversibility (DR) was defined as a summed difference score (SDS) between stress and rest images ≥2. CTCA and functional images were fused to assign each myocardial segment to the pertinent coronary territory. Stenosis severity, plaque characteristics and radiomic plaque features were assessed in the total length of the 3 main coronary vessels. In total, 1765 features were extracted from each vessel and a feature reduction and model creation pipeline was constructed [Figure 1]. Two separate datasets: a) coronary stenosis (≥50%) + plaque characteristics and b) coronary stenosis (≥50%) + plaque characteristics + radiomics were formulated and compared in terms of AUCs accordingly.

Results

A total of 292 coronary vessels (140 with corresponding PET-MPI data and 152 with SPECT MPI data) were analysed. Plaque burden and stenosis severity were the only independent predictors of impaired myocardial perfusion on PET-MPI, with an AUC = 0.749, (95% CI: 0.658–0.826). Stenosis severity, kurtosis, contrast, interquartile range and entropy were predictors of an abnormal PET-MPI result and their combination resulted in an AUC = 0.854, (95% CI: 0.775–0.914). The difference between the 2 models was statistically significant (p-diff: 0.02, 95% CI: 0.0165–0.194). Stenosis severity was the only predictor of a DR on SPECT-MPI, AUC = 0.624 (95% CI: 0.542–0.702). Small Dependence High Gray Level Emphasis, Cluster Prominence, Region Length, wavelet Median and square Median were predictors of a positive SPECT result, with AUC = 0.816, (95% CI: 0.745–0.875). The difference between the two models was statistically significant (p-diff: 0.006, 95% CI: 0.152–0.329)

Conclusion

Radiomic futures can be combined with anatomical and morphological characteristics of coronary lesions in CTCA imaging and provide valuable complementary information for characterizing functionally significant coronary lesions.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2022 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR)

The pleiotropic role of galectin-3 in melanoma progression: Unraveling the enigma

Melanoma is a highly aggressive skin cancer with poor outcomes associated with distant metastasis. Intrinsic properties of melanoma cells alongside the crosstalk between melanoma cells and surrounding microenvironment determine the tumor behavior. Galectin-3 (Gal-3), a ß-galactoside-binding lectin, has emerged as a major effector in cancer progression, including melanoma behavior. Data from melanoma models and patient studies reveal that Gal-3 expression is dysregulated, both intracellularly and extracellularly, throughout the stages of melanoma progression. This review summarizes the most recent data and hypotheses on Gal-3 and its tumor-modulating functions, highlighting its role in driving melanoma growth, invasion, and metastatic colonization. It also provides insight into potential Gal-3-targeted strategies for melanoma diagnosis and treatment.

Measurement of erythrocyte membrane mannoses to assess splenic function

Red blood cells (RBCs) lose plasma membrane in the spleen as they age, but the cells and molecules involved are yet to be identified. Sickle cell disease and infection by Plasmodium falciparum cause oxidative stress that induces aggregates of cross‐linked proteins with N‐linked high‐mannose glycans (HMGs). These glycans can be recognised by mannose‐binding lectins, including the mannose receptor (CD206), expressed on macrophages and specialised phagocytic endothelial cells in the spleen to mediate the extravascular haemolysis characteristic of these diseases. We postulated this system might also mediate removal of molecules and membrane in healthy individuals. Surface expression of HMGs on RBCs from patients who had previously undergone splenectomy was therefore assessed: high levels were indeed observable as large membrane aggregates. Glycomic analysis by mass spectrometry identified a mixture of Man_5‐9GlcNAc₂ structures. HMG levels correlated well with manual pit counts (r = 0.75–0.85). To assess further whether HMGs might act as a splenic reticuloendothelial function test, we measured levels on RBCs from patients with potential functional hyposplenism, some of whom exhibited high levels that may indicate risk of complications.

Myocardial tissue phenotyping by radiomic features of native T1 maps and machine learning enhances disease detection and classification

Background

Myocardial T1 mapping by cardiac magnetic resonance (CMR) is a useful technique to detect diffuse myocardial fibrosis, but a major limitation of T1 mapping is the significant overlap in native T1 values between health and disease.

Purpose

We explored whether radiomic features from T1 maps could enhance the diagnostic value of T1 mapping in distinguishing health from disease and classifying cardiac disease phenotypes.

Methods

In a total of 149 patients (n=30 with no evidence of heart disease, n=30 with LVH of various etiologies, n=61 with hypertrophic cardiomyopathy (HCM) and n=28 with cardiac amyloidosis) undergoing a CMR scan for various indications were included in this study. In addition to measuring native myocardial T1 values from T1 maps, we extracted a total of 843 radiomic features of myocardial texture and explored their value in disease classification.

Results

We first demonstrated that T1 mapping images are a rich source of extractable, quantifiable data. The first three principal components of the T1 radiomics were significantly and distinctively correlated with cardiac disease type. Unsupervised hierarchical clustering of the population by myocardial T1 radiomics was significantly associated with myocardial disease type (chi2=55.98, p<0.0001). After machine learning for feature selection, training with internal validation and external testing, a model of T1 radiomics had good diagnostic performance (AUC 0.753) for multinomial classification of disease phenotype (normal vs. LVH vs. HCM vs. amyloid). A subset of seven radiomic features outperformed mean native T1 values for classification between myocardial health vs. disease and HCM phenocopies (for normal: T1 AUC 0.549 vs. radiomics AUC 0.888, for LVH: T1 AUC 0.645 vs. radiomics AUC 0.790, for HCM T1 AUC 0.541 vs. radiomics AUC 0.638 and for amyloid T1 AUC 0.769 vs. radiomics AUC 0.840).

Conclusions

We have shown that specific imaging patterns in myocardial native T1 maps are linked to features of cardiac disease and we have provided for the first-time evidence that radiomic phenotyping can be used to enhance the diagnostic yield of native T1 mapping for myocardial disease detection and classification.

Funding Acknowledgement

Type of funding sources: None.

Tissue microRNA expression in aortic aneurysm dissection

Background

Dissection and other complications of ascending aortic aneurysms are potentially life-threatening. Several factors may be implicated in aneurysm progression and dissection. The role of tissue microRNAs may be of interest.

Purpose

To examine how serum biomarkers and tissue expression of microRNAs are associated with thoracic aortic aneurysms and dissection.

Methods

We compared three groups of patients; 21 patients with aneurysm of the aortic root, ascending aorta or aortic arch undergoing scheduled repair, 11 patients with acute Stanford type A aortic dissection who underwent emergency surgery and 18 patients with normal aortic diameter undergoing other cardiac surgery (control group). Prior to surgery, peripheral blood samples were obtained from patients, to assess osteoprotegerin and adiponectin levels with the ELISA method. Tissue samples from ascending aortic wall were obtained from patients during surgery. Following appropriate storage and homogenization, tissue Matrix Metalloproteinases (MMPs) 2 and 9 were measured with the ELISA method, while tissue microRNAs 29 and 195 were measured using qrtPCR, after RNA extraction.

Results

There was no significant difference among control, aneurysm and dissection groups in terms of age (62±10 years vs 66±12 years vs 59±12 years, p=0.052), gender distribution (77.8% male vs 81% male vs 90% male, p=0.28) or BMI (28.51±2.92 kg/m2 vs 25.72±3.09 kg/m2 vs 27.02±3.2 kg/m2, p=0.76). There was also no difference among control, aneurysm and dissection groups regarding hypertension (72% vs 62% vs 73%, p=0.73), diabetes mellitus (22% vs 19% vs 36%, p=0.54), smoking (44% vs 29% vs 46%, p=0.09) or dyslipidemia (78% vs 43% vs 55%, p=0.08). The groups of control subjects, aneurysms and dissections did not differ in osteoprotegerin [44 (28, 52) pmol/l vs 31 (28, 37) pmol/l vs 45 (24, 71) pmol/l, p=0.17], adiponectin [6,65 (2,39, 9,79) μg/ml vs 5,28 (2,34, 6,98) μg/ml vs 4,13 (2,49, 7,52) μg/ml, p=0.43], tissue MMP2 [0.97 (0.42, 27.66) ng/ml vs 9.12 (1.72, 61.49) ng/ml vs 2.51 (0.22, 235.72) ng/ml, p=0.34] and tissue MMP9 levels [0.96 (0.29, 8.56) ng/ml vs 10.31 (1.18, 25.58) ng/ml vs 2.76 (0.63, 54.83) ng/ml, p=0.09] (Figure 1). Importantly, tissue expression of mir29 was 2.11-fold higher in the dissection group (p=0.001) and 2.99-fold higher in the aneurysm group (p<0.001) compared to the control group. Tissue expression of mir195 was 2.72-fold higher in the dissection group (p<0.001) and 2.00-fold lower in the aneurysm group (p=0.08) compared to the control group (Figure 2).

Conclusions

These findings highlight the role of epigenetic modifications through altered microRNA tissue expression in aortic wall synthesis, extracellular matrix degradation and progress of aneurysm formation and dissection. The exact role of microRNA expression in aortic dilatation and dissection, as well as their role as potential biomarkers, merit further validation.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

A human arterial transcriptomic signature predicts major adverse cardiac events and identifies novel, redox-related therapeutic targets within the vascular wall

Background

The transcriptomic profile of the human vascular wall is implicated in a range of pathologies. RNA sequencing technologies allow for interrogation of gene expression patterns that are associated with clinical outcomes and can guide future research and drug development.

Purpose

To apply discovery network transcriptomics to internal mammary arteries (IMAs) obtained from patients undergoing cardiac surgery, in order to identify redox-related molecular pathways within the vascular wall that can be treated therapeutically.

Methods

Arm 1 included 377 patients in whom segments of IMA were used for ex-vivo quantification of NADPH-stimulated superoxide production by lucigenin-enhanced chemiluminescence. Arm 2 included 205 patients in whom bulk RNA sequencing was performed in RNA isolated from IMA, and the WGCNA package used for the analyses. The association with future incidence of major adverse cardiac events (MACE: cardiovascular death, non-fatal myocardial infarction, and stroke) was assessed using Cox regression models (adjusted for age, sex, hypertension, dyslipidaemia, diabetes mellitus, body mass index, smoking, and plasma TNFa).

Results

Over a median follow-up of 4.84 years [IQR: 2.03–7.14], 38 (11.2%) MACE occurred in Arm 1. High arterial NADPH-stimulated superoxide was independently associated with MACE risk (Adj. HR [95% CI]: 2.62 [1.13–6.07] high group, p=0.02). Unsupervised transcriptomic analysis in Arm 2 allowed identification of 10 coexpressed gene “modules”. Eigengenes summarising modular coexpression signatures were then correlated with NADPH-stimulated superoxide revealing the red module (a) as the most significant (rho=0.19, p=0.01). In survival analysis the red module showed significant correlation with MACE (Adj. HR [95% CI]: 1.40 [1.00–1.95] per SD, p=0.04). For an optimal cut-off, patients with high eigengene values for the red module showed a 4-fold higher risk of MACE (b), and significantly higher arterial oxidative stress (c). Enrichment analysis (performed with Enrichr) of genes in the red module revealed “Electron Transport Chain”, “Oxidative phosphorylation”, “Striated Muscle Contraction Pathway”, and “Glycolysis and Gluconeogenesis” amongst the top enriched pathways (d).

Conclusion

We present for the first time a novel human arterial transcriptomic signature reflecting changes in redox state, which identifies long-term cardiovascular risk. Targeting pathways in the vasculature related with the mitochondrial electron transport chain, the contractile mechanism, or glucose metabolism may lead to the development of novel therapeutics in cardiovascular disease.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): EPSRC-EP/N509711/1-2119518British Heart Foundation Figure 1

Major differences in glycosylation and Fucosyltransferase expression in low-grade versus high-grade bladder cancer cell lines

Bladder cancer is the ninth most frequently diagnosed cancer worldwide, and there is a need to develop new biomarkers for staging and prognosis of this disease. Here we report that cell lines derived from low-grade and high-grade bladder cancers exhibit major differences in expression of glycans in surface glycoproteins. We analyzed protein glycosylation in three low-grade bladder cancer cell lines RT4 (grade-1-2), 5637 (grade-2), and SW780 (grade-1), and three high-grade bladder cancer cell lines J82COT (grade-3), T24 (grade-3), and TCCSUP (grade-4), with primary bladder epithelial cells, A/T/N, serving as a normal bladder cell control. Using a variety of approaches including flow cytometry, immunofluorescence, glycomics, and gene expression analysis, we observed that the low-grade bladder cancer cell lines RT4, 5637, and SW780 express high levels of the fucosylated Lewis x (Lex) antigen (CD15) (Galβ1-4(Fucα1-3) GlcNAcβ1-R), while normal bladder epithelial A/T/N cells lack Lex expression. T24 and TCCSUP cells also lack Lex, whereas J82COT cells express low levels of Lex. Glycomics analyses revealed other major differences in fucosylation and sialylation of N-glycans between these cell types. O-glycans are highly differentiated, as RT4 cells synthesize core 2-based O-glycans that are lacking in the T24 cells. These differences in glycan expression correlated with differences in RNA expression levels of their cognate glycosyltransferases, including α1-3/4-fucosyltransferase genes. These major differences in glycan structures and gene expression profiles between low- and high-grade bladder cancer cells suggest that glycans and glycosyltransferases are candidate biomarkers for grading bladder cancers.

Loss of α2-6 sialylation promotes the transformation of synovial fibroblasts into a pro-inflammatory phenotype in arthritis

In healthy joints, synovial fibroblasts (SFs) provide the microenvironment required to mediate homeostasis, but these cells adopt a pathological function in rheumatoid arthritis (RA). Carbohydrates (glycans) on cell surfaces are fundamental regulators of the interactions between stromal and immune cells, but little is known about the role of the SF glycome in joint inflammation. Here we study stromal guided pathophysiology by mapping SFs glycosylation pathways. Combining transcriptomic and glycomic analysis, we show that transformation of fibroblasts into pro-inflammatory cells is associated with glycan remodeling, a process that involves TNF-dependent inhibition of the glycosyltransferase ST6Gal1 and α2-6 sialylation. SF sialylation correlates with distinct functional subsets in murine experimental arthritis and remission stages in human RA. We propose that pro-inflammatory cytokines remodel the SF-glycome, converting the synovium into an under-sialylated and highly pro-inflammatory microenvironment. These results highlight the importance of glycosylation in stromal immunology and joint inflammation.

Site-specific characterization of SARS-CoV-2 spike glycoprotein receptor-binding domain

The novel coronavirus SARS-CoV-2, the infective agent causing COVID-19, is having a global impact both in terms of human disease as well as socially and economically. Its heavily glycosylated spike glycoprotein is fundamental for the infection process, via its receptor-binding domains interaction with the glycoprotein angiotensin-converting enzyme 2 on human cell surfaces. We therefore utilized an integrated glycomic and glycoproteomic analytical strategy to characterize both N- and O- glycan site-specific glycosylation within the receptor-binding domain. We demonstrate the presence of complex-type N-glycans with unusual fucosylated LacdiNAc at both sites N331 and N343 and a single site of O-glycosylation on T323.

Red blood cell mannoses as phagocytic ligands mediating both sickle cell anaemia and malaria resistance

In both sickle cell disease and malaria, red blood cells (RBCs) are phagocytosed in the spleen, but receptor-ligand pairs mediating uptake have not been identified. Here, we report that patches of high mannose N-glycans (Man_5-9GlcNAc₂), expressed on diseased or oxidized RBC surfaces, bind the mannose receptor (CD206) on phagocytes to mediate clearance. We find that extravascular hemolysis in sickle cell disease correlates with high mannose glycan levels on RBCs. Furthermore, Plasmodium falciparum-infected RBCs expose surface mannose N-glycans, which occur at significantly higher levels on infected RBCs from sickle cell trait subjects compared to those lacking hemoglobin S. The glycans are associated with high molecular weight complexes and protease-resistant, lower molecular weight fragments containing spectrin. Recognition of surface N-linked high mannose glycans as a response to cellular stress is a molecular mechanism common to both the pathogenesis of sickle cell disease and resistance to severe malaria in sickle cell trait.

Discovery of O-Linked Carbohydrate on HIV-1 Envelope and Its Role in Shielding against One Category of Broadly Neutralizing Antibodies

Approximately 50% of the mass of the Envelope (Env) glycoprotein surface subunit (gp120) of human immunodeficiency virus type 1 (HIV-1) is composed of N-linked carbohydrate. Until now, the dogma has been that HIV-1 lacks O-linked carbohydrate on Env. Here we show that a subset of patient-derived HIV-1 isolates contain O-linked carbohydrate on the variable 1 (V1) domain of Env gp120. We demonstrate the presence of this O-glycosylation both on virions and on gp120 expressed as a secreted protein. Further, we establish that these O-linked glycans can confer a more than 1,000-fold decrease in neutralization sensitivity (IC₅₀) to V3-glycan broadly neutralizing antibodies. These findings uncover a structural modification to the HIV-1 Env and suggest a functional role in promoting viral escape from one category of broadly neutralizing antibodies.

Efficient inhibition of O-glycan biosynthesis using the hexosamine analog Ac5GalNTGc

There is a critical need to develop small-molecule inhibitors of mucin-type O-linked glycosylation. The best-known reagent currently is benzyl-GalNAc, but it is effective only at millimolar concentrations. This article demonstrates that Ac₅GalNTGc, a peracetylated C-2 sulfhydryl-substituted GalNAc, fulfills this unmet need. When added to cultured leukocytes, breast cells, and prostate cells, Ac₅GalNTGc increased cell-surface VVA binding by ∼10-fold, indicating truncation of O-glycan biosynthesis. Cytometry, mass spectrometry, and western blot analysis of HL-60 promyelocytes demonstrated that 50-80 μM Ac₅GalNTGc prevented elaboration of 30%-60% of the O-glycans beyond the Tn-antigen (GalNAcα1-Ser/Thr) stage. The effect of the compound on N-glycans and glycosphingolipids was small. Glycan inhibition induced by Ac₅GalNTGc resulted in 50%-80% reduction in leukocyte sialyl-Lewis X expression and L-/P-selectin-mediated rolling under flow conditions. Ac₅GalNTGc was pharmacologically active in mouse. It reduced neutrophil infiltration to sites of inflammation by ∼60%. Overall, Ac₅GalNTGc may find diverse applications as a potent inhibitor of O-glycosylation.

Human erythrocyte surface fucose expression increases with age and hyperglycemia

Background: Reactive oxygen species and other free radicals, together with glucose and its metabolites are believed to play important roles in the aging process. The carbohydrate components of glycosylated proteins are important in mediating cell-cell interactions and a role has been suggested for them in the aging process. Erythrocytes are critical cells in the human body, heavily glycosylated and relatively easily available and so are good candidates to yield insights into how patterns of glycosylation change with age and disease. It has been claimed, based on a periodic acid Schiff assay, that human aging is associated with a decline of erythrocyte surface sialic acids. Plant lectins allow for more specific assays for glycans, including determining the linkage of sialic acids and analysis of single cells by flow cytometry. Methods: Plant lectins, including Maackia amurensis lectin II (MAL), binding to α-2,3 linked sialic acids and Sambucus nigra (SNA), α-2,6 sialic acids, were used in flow cytometry and western blot of erythrocyte surface membrane. N-glycomics mass spectrometry determines glycan structures. Donors varying in age and hyperglycemia, as indicated by HbA1c were analysed. Results: Erythrocyte surface sialic acids have no significant associations with donor age. A combination of storage and cellular aging produces a specific loss of α-2,6 sialic acids. By contrast, erythrocyte surface terminal fucoses increase significantly with donor age. In order to determine which aspects of aging are important in determining this change, we investigated whether this novel human aging biomarker is associated with higher plasma glucose values, assessed by glycated hemoglobin (HbA1c) and reactive oxygen species (ROS) generation. Fucose levels were associated with HbA1c levels, but not ROS generation. Conclusion: Our study identifies novel glycan-based biomarkers for human aging and disease. The simplicity of lectin-based assays provide an attractive cellular tool to study aging and disease processes.

CCTA-derived functional and morphological features and their comparative performance in predicting impaired coronary vasodilatation by PET-myocardial perfusion imaging

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported in part from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2020 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR) , no. GR 5002802 ,and by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach”, Project no. 504776

onbehalf

EVINCI-SMARTOOL

Background/Objectives: The relationship between biomechanical characteristics of a coronary lesion with myocardial blood flow has not been studied. We investigated the relationship between local endothelial shear stress (ESS) and computed tomography coronary angiography (CTCA)-derived anatomical and plaque characteristics data with impaired vasodilating capability assessed by positron emission tomography myocardial perfusion imaging (PET-MPI).

Methods

A total of 92 coronary vessels of 53 patients who have undergone both CTCA and PET-MPI with 15O-water or 13N-ammonia were analysed. PET was considered abnormal when > 1 contiguous segments showed both stress Myocardial Blood Flow (MBF) ≤2.3mL/g/min and Myocardial Flow Reserve (MFR) ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively.  CTCA images were used to assess stenosis severity, lesion specific total plaque volume (PV), non-calcified PV and calcified PV as well as plaque phenotype. ESS was calculated for the full length of a lesion (total), as well as in the proximal, minimum lumen area and distal lesion segments.

Results

ESS was weakly correlated with total PV (rho = 0.273, p = 0.008), non-calcified PV (rho = 0.247, p = 0.017) and the volume of necrotic core (rho = 0.242, p = 0.02). ESS increased progressively with stenosis severity (p ≤ 0.001). ΕSS was also higher in functionally significant vs. non-significant lesions (10.4 [8.04-54.4] Pa vs. 3.9 [2.32-7.29] Pa, p ≤0.001). Addition of ESS to stenosis severity improved prediction (Δ[AUC]:0.113, 95% CI: 0.055 to 0.171, p = 0.0001) of functionally significant lesions.

Conclusion

There is a weak positive association between lesion-specific ESS and plaque volume. ESS increases progressively with stenosis severity and is higher in functionally significant lesions by PET-MPI. The addition of ESS to CTCA-anatomical information improves prediction of an abnormal PET-MPI result.

Prediction of impaired myocardial blood flow (MBF) with the use of machine learning techniques on CTCA based parameters

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported in part from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2020 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR) , no. GR 5002802 ,and by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach”, Project no. 504776

Background

Computed Tomography Coronary Angiography (CTCA) is a non-invasive imaging modality, used effectively for anatomo-functional assessment of coronary artery disease (CAD). Machine learning (ML) processes can effectively allow the extraction of useful information from multidimensional feature spaces for evaluation of coronary lesions.

Purpose

To investigate the ability of ML for predicting impaired myocardial blood flow (MBF) by combining computational fluid dynamics (CFD) derived parameters with quantitative plaque burden, plaque morphology and anatomical characteristics obtained from CTCA.

Methods

53 patients (31 male, mean age 64.7 ± 7.1 years) with intermediate pre-test likelihood of CAD who underwent CTCA and PET-MPI were included. PET was considered positive when > 1 contiguous segment demonstrated MBF ≤ 2.3 mL/g/min for 15O-water or ≤ 1.79 for 13N-ammonia respectively. CFD derived parameters such as a previously validated, virtual functional assessment index (vFAI), segmental endothelial shear stress (ESS), as well as anatomical and plaque characteristics were assessed. Seven classifiers were implemented and internally validated using 5-fold cross validation, repeated 1000 times. Using sequential forward selection (SFS), the highest rank features combination, based on appearances in the highest mean area under curve (AUC) classification scheme, was selected and features performance was evaluated following exhaustive search (ES).

Results

92 coronary segments were analyzed and 34 features derived from CTCA were extracted. Classifiers performance are depicted in Figure A. k-NN was the best classifier with AUCmean = 0.791 (SENSmean= 0.622, SPECmean = 0.840, p < 0.05). Clusters of features and number of appearances are presented in Figure B. The combination of vFAI, stenosis severity and lumen area demonstrated the highest AUC (1473 times). ES results are depicted in Figure C. The combination of vFAI and lumen area was the best predictor among all the combinations (AUCmean = 0.830, SENSmean =0.61, SPECmean =0.83, p < 0.05) followed by vFAI and stenosis severity (AUCmean = 0.81, SENSmean =0.72, SPECmean = 0.87, p < 0.05) and vFAI alone (AUCmean = 0.806, SENSmean =0.61, SPECmean =0.87, p < 0.05).

Conclusion

ML analysis is feasible for predicting with reasonable specificity abnormal MBF by PET, using a combination of CFD derived parameters and anatomical features. vFAI as a single characteristic was a specific predictor of impaired MBF, whilst in combination with stenosis severity, maintained almost the same AUC and specificity values and resulted in improved sensitivity. On the other hand, addition of lumen area to vFAI, increases the AUC and provides a relatively good specificity but low  sensitivity.

Abstract Figure 1

Direct effects of canagliflozin on human myocardial redox signalling: a novel role for SGLT1 inhibition

Background

Recent clinical trials have demonstrated a role for sodium glucose cotransporter 2 (SGLT2) inhibitors in improving cardiovascular outcomes in heart failure patients, but the underlying mechanisms remain unknown. We investigated the direct effects of canagliflozin, a non-selective SGLT1/SGLT2 inhibitor on myocardial redox signalling in humans.

Methods

Study 1 included 364 patients undergoing cardiac surgery. Human right atrial appendage biopsies, obtained during surgery, were used to quantify the sources of superoxide (O2.-) and the gene expression of inflammation, fibrosis and myocardial stretch markers. In Study 2, myocardial biopsies from 51 patients were used ex vivo to study the direct effects of canagliflozin on O2.- generation and understand its role in controlling the activity of NADPH-oxidases and uncoupled nitric oxide synthase (NOS). Finally, we used differentiated H9C2 and human primary cardiomyocytes (hCM) to further characterise the key regulatory mechanisms (Study 3).

Results

SGLT1 was abundantly expressed in the human myocardial biopsies and hCM whilst SGLT2 was barely detectable. SGLT1 expression levels were positively correlated with basal O2.- production and the expression of natriuretic peptides, proinflammatory cytokines and pro-fibrotic markers in human myocardial biopsies from study 1. Incubation of human myocardium with canagliflozin significantly reduced basal and NADPH-oxidase-derived O2.- via AMP kinase (AMPK)-mediated suppression of GTP-activation and consequent reduction of membrane translocation of Rac1, an NADPH-oxidase subunit. This resulted in reduced oxidation and increased bioavailability of tetrahydrobiopterin, the nitric oxide synthase (NOS) co-factor essential for enzymatic coupling, leading to improved NOS coupling. These findings were replicated in hCM, where canagliflozin was shown to regulate AMP/ATP ratio, which could be upstream of AMPK activation. The effects of canagliflozin were significantly attenuated by knocking-down SGLT1 in hCM. Transcriptional profiling of hCM treated with canagliflozin revealed that canagliflozin had striking effects on myocardial redox signalling, causing suppression of apoptotic and inflammatory pathways in the human heart.

Conclusions

We demonstrate for the first time in humans that canagliflozin suppresses myocardial NADPH-oxidase activity and improves NOS coupling through an SGLT1/AMPK/Rac1-mediated pathway, leading to global anti-inflammatory and anti-apoptotic effects in the human myocardium. These findings provide a mechanistic basis for the beneficial effects of SGLT1/2 inhibitors in patients with heart failure.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): 1. British Heart Foundation (FS/16/15/32047 and PG/13/56/30383 to CA, CH/16/1/32013 to KC, and Centre of Research Excellence award RG/13/1/30181), 2. The Japanese Heart Rhythm Society-European Heart Rhythm Association fellowship grant sponsored by Biotronik.

Coronary CT angiography derived features for predicting an abnormal pet myocardial perfusion imaging: a machine learning approach

Background

Computed Tomography Coronary Angiography (CTCA) is an effective non-invasive imaging modality for anatomo-functional assessment of coronary artery disease (CAD). Machine learning (ML) algorithms allow extraction and process of useful information from multidimensional spaces for evaluation of coronary lesions.

Purpose

To investigate the ability of ML to integrate computational fluid dynamics (CFD) derived parameters with quantitative plaque burden, plaque morphology and anatomical characteristics for predicting impaired myocardial flow reserve by PET myocardial perfusion imaging (MPI).

Methods

49 patients (29 male, mean age 65.3±6.3 years) with intermediate pre-test likelihood of CAD who underwent CTCA and PET-MPI were included. PET was considered positive when >1 contiguous segment demonstrated Myocardial flow reserve (MFR) ≤2.5 mL/g/min for 15O-water or ≤2.0 for 13N-ammonia respectively. CDF derived parameters such as a previously validated CT-FFR surrogate, virtual functional assessment index (vFAI), segmental endothelial shear stress (ESS), as well as anatomical and plaque characteristics were assessed. k-nearest neighbor (k-NN), support vector machines (SVM) and feedforward neural networks (FF-NN) were implemented. ML was internally validated using 5-fold cross validation, repeated 100 times. Using sequential forward selection (SFS), the 5 highest rank features based on appearances in each classification scheme were selected and following exhaustive search (ES) the best features combinations were identified. Each classifier's performance was evaluated using an area-under-receiver operating characteristic curve (AUC) analysis.

Results

85 coronary segments were analyzed and 28 features derived from CTCA were extracted. The features ranking for every classifier are depicted in Figure 1. k-NN using a combination only of ESS in the proximal (ESSprox) and distal segment achieved an AUC=0.78 (Sens=0.71, Spec=0.77, p<0.05) for predicting a positive PET result. Combining ESSprox with burden fibrofatty tissue and non-calcified plaque burden, SVM achieved an AUC=0.75 (Sens=0.74, Spec=0.67, p<0.05) whilst for FF-NN, the corresponding AUC was 0.79 (Sens=0.76, Spec=0.7, p<0.05) using ESSprox, vFAI and % Fibrofatty volume. Among the best features combinations, ESSprox was the most consistent one achieving an AUC=0.75 (Sens=0.66, Spec=0.73, p<0.05) for k-NN, AUC=0.73 (Sens=0.58, Spec=0.59, p<0.05), for SVM and an AUC=0.73 (Sens=0.63, Spec=0.62, p<0.05) for FF-NN respectively.

Conclusion

ML analysis is feasible for predicting abnormal MFR by PET using a combination of CFD derived parameters, anatomical and morphological features. ESSprox was present in every combination of best features. As a single characteristic was a moderate predictor of impaired MFR, whilst in combination with plaque characteristics and CFD derived features resulted in improved sensitivity and specificity.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This research is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human, Resources Development, Education and Lifelong Learning 2014-2020” in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach” and from p-Med GR 5002802

Association of osteoprotegerin with ascending aortic dissection

Background

Thoracic aortic dissections are among the cardiovascular diseases with the highest mortality rates. Their often belated diagnosis and, hence, poor prognosis call for further research of their pathophysiology and possible biomarkers that will aid early diagnosis and increase survival rates. Osteoprotegerin is a known biomarker in cardiovascular disease, but it is yet to be determined whether it participates in aortic disease and thoracic aortic dissection in particular.

Purpose

This clinical study aimed at researching the role of osteoprotegerin in thoracic aortic aneurysm and dissection.

Methods

We compared three groups of patients; 20 patients with ascending aortic aneurysm (AAA), 10 patients with acute ascending aortic dissection (AAD) and 16 patients with normal aortic diameter undergoing cardiac surgery for other indication (control group). Serum samples were obtained from patients before surgery and osteoprotegerin levels were measured using the ELISA method.

Results

One-way analysis of variance revealed a significant association between the examined groups of patients and levels of osteoprotegerin (AAD: 62.72±44.53 pmol/L, AAA: 33.43±8.08 pmol/L, Control: 48.61±29.47 pmol/L, p=0.03). Importantly, after post-hoc analysis osteoprotegerin levels were found to be increased in patients with AAD compared to patients with uncomplicated AAA (62.72±44.53 pmol/L vs 33.43±8.08 pmol/L, p=0.03) (Figure 1), whereas there was no statistically significant difference between patients with AAA and the control group (33.43±8.08 pmol/L vs 48.61±29.47 pmol/L, p=0.34).

Conclusions

These findings suggest that osteoprotegerin may participate in the pathophysiology of aortic dissection but not in mechanisms of aortic dilatation. Therefore, detection of elevated osteoprotegerin levels in patients with diagnosed ascending aortic aneurysms might suggest an increased probability of dissection and, therefore, aid the decision-making process.

Figure 1

Funding Acknowledgement

Type of funding source: None

Hydroxychloroquine for colchicine-resistant glucocorticoid-dependent idiopathic recurrent pericarditis: an observational prospective study

Background

Glucocorticoid (GC)-dependent, colchicine-resistant idiopathic recurrent pericarditis (IRP) remains a clinical challenge. We assessed for the first time the efficacy and safety of hydroxychloroquine (HCQ) in IRP.

Methods

This is a single center, post hoc analysis of prospectively collected data of 15 patients with refractory to standard therapy (colchicine plus either GC or anakinra) IRP (≥3 recurrences, disease duration ≥12 months and inability to wean off treatment) treated with HCQ (400 mg/day). These patients were matched 1:1 for age, sex, and treatment type to IRP patients receiving standard-of-care treatment (control group, n=15). Pericarditis recurrence, the time and C-reactive protein (CRP) levels at 1st flare, the % of patients able to achieve a ≥50% reduction of baseline GC dose and the % reduction of GC dose were compared between groups.

Results

Almost all patients (n=29) but one in the HCQ group (14/15) relapsed during follow-up. However, HCQ treatment was associated with an increased median time of flare-free survival (increase by 4 weeks compared to controls) and reduced hazard ratio for flare in survival analysis (HR=0.36, 95% CI 0.16–0.77, p=0.009). HCQ was also associated with a higher proportion of patients obtaining a ≥50% dose reduction of GCs (33.3% vs. 0% in the control group, p=0.037) and reduced GC dose (HCQ: −43.5% vs. control: −4.5%, p<0.001). There were no signficant differences in CRP levels at flare between groups (p=0.615).

Conclusions

In this prospective study, HCQ use was associated with a GC-sparing effect and an increased flare-free survival period in patients with colchicine resistant GC-dependent IRP.

Funding Acknowledgement

Type of funding source: None

Relationship between endothelial shear stress, plaque burden and stenosis severity and their comparative performance in predicting impaired coronary vasodilation by pet myocardial perfusion imaging

Background

Advances in CTCA imaging enable assessment of coronary plaque burden, a predictor of myocardial perfusion abnormalities and more recently, with the use of computational fluid dynamics (CFD) of endothelial shear stress (ESS), an established contributor to atherosclerotic plaque development and progression.

Purpose

To investigate the relationship of local endothelial shear stress (ESS) and plaque burden (PB) between them and with stenosis severity as well as their comparative performance in predicting impaired coronary vasodilating capability assessed by PET myocardial perfusion imaging (MPI).

Methods

49 patients (29 males, mean age 65.3±6.3 years, intermediate pre-test likelihood of coronary artery disease, CAD), who underwent PET-MPI with 15O-water or 13N-ammonia and CTCA were included. PET was considered abnormal when >1 contiguous segment showed both stress Myocardial Blood Flow ≤2.3 mL/g/min and Myocardial Flow Reserve ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively. On CTCA, stenosis (sten) severity was classified as: <30%, 31–50%, 51–70% and 71–90%. CFD were applied to every vessel, assuming a mean pressure of 100 mmHg as the inlet boundary condition and a coronary velocity profile of 1 ml/sec as the outlet. ESS was calculated for the full length of a stenosis (total), as well as in the proximal (prox), minimum lumen area (MLA) and distal (dist) stenotic segments. Atherosclerotic PB was defined as lesion plaque volume/lesion vessel volume ×100.

Results

85 coronary vessels were evaluated. There was a positive correlation between ESS and PB (r(total)=0.544, r(prox)=0.528, r(MLA)=0.529, r(dist)=0.474, p<0.001 for all). All ESS indices and PB increased progressively with stenosis severity compared to segments with a <30% stenosis (p≤0.004 for all comparisons). ESS indices and PB were also higher in lesions demonstrating impaired vasodilating capacity compared to those without (p≤0.02 for all comparisons, figure 1). All ESS indices performed equally with PB and sten >50% in predicting an abnormal PET MPI, (AUC: from 0.682 to 0.780, p-diff >0.5 for all comparisons). The pairwise combination of sten >50% with the ESS segments, except the distal one, increased the predictive ability of the model over stenosis alone (AUC (sten >50% + ESS(total)) = 0.80, AUC (sten >50% + ESS(prox)) = 0.797, AUC (sten >50% + ESS(MLA)) = 0.822, p-diff ≤0.01 for all comparisons, AUC (sten >50% + ESS(dist)) = 0.768, p-diff=0.07).

Conclusion

There is a low to moderate positive association between lesion plaque burden and ESS indices. Like PB, ESS increases progressively with stenosis severity and is higher in lesions paired with abnormal PET results. ESS is a moderate predictor of impaired vasodilating capability, performing equally with PB and stenosis severity. The addition of ESS to stenosis severity can improve prediction of an abnormal PET result.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This study is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning 2014-2020” in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach” and from p-Med GR 5002802

Metabolic precision labeling enables selective probing of O-linked N-acetylgalactosamine glycosylation

Protein glycosylation events that happen early in the secretory pathway are often dysregulated during tumorigenesis. These events can be probed, in principle, by monosaccharides with bioorthogonal tags that would ideally be specific for distinct glycan subtypes. However, metabolic interconversion into other monosaccharides drastically reduces such specificity in the living cell. Here, we use a structure-based design process to develop the monosaccharide probe N-(S)-azidopropionylgalactosamine (GalNAzMe) that is specific for cancer-relevant Ser/Thr(O)-linked N-acetylgalactosamine (GalNAc) glycosylation. By virtue of a branched N-acylamide side chain, GalNAzMe is not interconverted by epimerization to the corresponding N-acetylglucosamine analog by the epimerase N-acetylgalactosamine-4-epimerase (GALE) like conventional GalNAc-based probes. GalNAzMe enters O-GalNAc glycosylation but does not enter other major cell surface glycan types including Asn(N)-linked glycans. We transfect cells with the engineered pyrophosphorylase mut-AGX1 to biosynthesize the nucleotide-sugar donor uridine diphosphate (UDP)-GalNAzMe from a sugar-1-phosphate precursor. Tagged with a bioorthogonal azide group, GalNAzMe serves as an O-glycan-specific reporter in superresolution microscopy, chemical glycoproteomics, a genome-wide CRISPR-knockout (CRISPR-KO) screen, and imaging of intestinal organoids. Additional ectopic expression of an engineered glycosyltransferase, "bump-and-hole" (BH)-GalNAc-T2, boosts labeling in a programmable fashion by increasing incorporation of GalNAzMe into the cell surface glycoproteome. Alleviating the need for GALE-KO cells in metabolic labeling experiments, GalNAzMe is a precision tool that allows a detailed view into the biology of a major type of cancer-relevant protein glycosylation.

Vulpeculin: a novel and abundant lipocalin in the urine of the common brushtail possum, Trichosurus vulpecula

Lipocalins are a family of secreted proteins. They are capable of binding small lipophilic compounds and have been extensively studied for their role in chemosignalling in rodent urine. Urine of the common brushtail possum (Trichosurus vulpecula) contains a prominent glycoprotein of 20 kDa, expressed in both sexes. We have isolated this protein and determined its primary sequence by mass spectrometry, including the use of metabolic labelling to resolve the leucine/isoleucine isobaric ambiguity. The protein sequence was identified as a lipocalin, and phylogenetic analysis grouped the protein with other marsupial lipocalin sequences in a phylogenetic clade distinct from established cross-species lipocalin sub-families. The pattern of expression in possum urine and the similarity in sequence and structure to other lipocalins suggests this protein may have a role in brushtail possum chemosignalling.

Analysis of N- and O-Linked Glycosylation: Differential Glycosylation after Rat Spinal Cord Injury

Glycosylation is a fundamental cellular process that has a dramatic impact on the functionality of glycoconjugates such as proteins or lipids and mediates many different biological interactions including cell migration, cellular signaling, and synaptic interactions in the nervous system. In spinal cord injury (SCI), all of these cellular processes are altered, but the potential contributions of glycosylation changes to these alterations has not been thoroughly investigated. We studied the glycosylation of injured spinal cord tissue from rats that received a contusion SCI. The N- and O-linked glycosylation was assessed at 3 and 14 days post-injury (DPI), and compared with uninjured control and time-matched sham spinal tissue. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and tandem MS (MS/MS) were performed to analyze carbohydrate structures. Results revealed diverse and abundant glycosylation in all groups, with some carbohydrate structures differentially produced in SCI animals compared with uninjured controls and shams. One such change occurred in the abundance of the Sda structure, Neu5Ac-α-(2,3)-[GalNAc-β-(1,4)-]Gal-β-(1,4)-GlcNAc, which was increased in SCI samples compared with shams and non-injured controls. Immunohistochemistry (IHC) and western blot were performed on SCI and sham samples using the CT1 antibody, which recognizes the terminal trisaccharide of Sda with high specificity. Both of these metrics confirmed elevated Sda structure in SCI tissue, where IHC further showed that Sda is expressed mainly by microglia. The results of these studies suggest that SCI causes a significant alteration in N- and O-linked glycosylation.

Insights into the hyperglycosylation of human chorionic gonadotropin revealed by glycomics analysis

Human chorionic gonadotropin (hCG) is a glycoprotein hormone that is essential for the maintenance of pregnancy. Glycosylation of hCG is known to be essential for its biological activity. "Hyperglycosylated" variants secreted during early pregnancy have been proposed to be involved in initial implantation of the embryo and as a potential diagnostic marker for gestational diseases. However, what constitutes "hyperglycosylation" is not yet fully understood. In this study, we perform comparative N-glycomic analysis of hCG expressed in the same individuals during early and late pregnancy to help provide new insights into hCG function, reveal new targets for diagnostics and clarify the identity of hyperglycosylated hCG. hCG was isolated in urine collected from women at 7 weeks and 20 weeks' gestation. hCG was also isolated in urine from women diagnosed with gestational trophoblastic disease (GTD). We used glycomics methodologies including matrix assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry (MS) and MS/MS methods to characterise the N-glycans associated with hCG purified from the individual samples. The structures identified on the early pregnancy (EP-hCG) and late pregnancy (LP-hCG) samples corresponded to mono-, bi-, tri-, and tetra-antennary N-glycans. A novel finding was the presence of substantial amounts of bisected type N-glycans in pregnancy hCG samples, which were present at much lower levels in GTD samples. A second novel observation was the presence of abundant LewisX antigens on the bisected N-glycans. GTD-hCG had fewer glycoforms which constituted a subset of those found in normal pregnancy. When compared to EP-hCG, GTD-hCG samples had decreased signals for tri- and tetra-antennary N-glycans. In terms of terminal epitopes, GTD-hCG had increased signals for sialylated structures, while LewisX antigens were of very minor abundance. hCG carries the same N-glycans throughout pregnancy but in different proportions. The N-glycan repertoire is more diverse than previously reported. Bisected and LewisX structures are potential targets for diagnostics. hCG isolated from pregnancy urine inhibits NK cell cytotoxicity in vitro at nanomolar levels and bisected type glycans have previously been implicated in the suppression of NK cell cytotoxicity, suggesting that hCG-related bisected type N-glycans may directly suppress NK cell cytotoxicity.

P6267Novel direct effects of SGLT2 inhibitor, Canagliflozin, on myocardial redox state in humans

Background

Sodium glucose cotransporter 2 (SGLT2) inhibitors are antidiabetic drugs that control plasma glucose levels by inhibiting reabsorption of glucose in kidney. Recent clinical trials have suggested a class effect of SGLT2 inhibitors in preventing hospitalization due to heart failure. However, the underlying mechanism has not been fully elucidated.

Purpose

We investigated the direct effect of the SGLT2 inhibitor, Canagliflozin (Cana), on myocardial redox state in humans.

Methods

The study included 48 patients undergoing cardiac surgery. Fresh myocardial tissues were incubated ex vivo with or without Cana and then used for superoxide quantification and Western immunoblotting. NADPH-oxidases activity was evaluated with NADPH 100μM stimulation, while nitric oxide synthase (NOS) coupling was assessed by using N(ω)-nitro-L-arginine methyl ester (L-NAME, a NOS inhibitor). A human cardiomyocyte (HCM) cell line was also used for in vitro validation of the effects of Cana on myocardium.

Results

Ex vivo incubation of myocardium with Cana significantly reduced baseline (A) and NADPH-oxidase-derived O2·− (B) and improved NOS coupling reflected by positive L-NAME delta O2·− values (C). Regulation of NADPH-oxidases activity by Cana was found to result from reduced GTP-activation (D) and consequent membrane translocation (E) of Rac1, a key subunit of NADPH-oxidases. Cana also reduced tetrahydrobiopterin (BH4) oxidation, increasing its bioavailability (F), which is a key mechanism to improve NOS coupling. Incubation with Cana enhanced phosphorylation of AMPK, and the downstream signalling, ACC (not shown). Additional Compound C, which is inhibitor of AMPK, significantly reversed these effects of Cana (A, B, C, D, E, F). These findings were replicated in HCM (not shown). In line with these, Cana increased the ADP/ATP ratio of cytoplasm in HCM, which could provide an upstream mechanism for AMPK activation.

Conclusions

We demonstrate for the first time in humans, that Cana suppresses myocardial NADPH-oxidases activity and improves NOS coupling through an AMPK-mediated pathway. This could be an underlying mechanism for the cardioprotective effects of SGLT2 inhibitors.

P2483Differential effects of novel antidiabetics on arterial stiffness in patients with type 2 diabetes mellitus

Background

Arterial stiffness flags increased cardiovascular disease risk in type 2 diabetes mellitus (T2DM) patients. There is limited data on how novel anti-diabetic agents affect arterial stiffness.

Purpose

To investigate the effects of novel anti-diabetic agents on arterial stiffness in T2DM patients.

Patients and methods

We enrolled 64 consecutive patients under stable antidiabetic therapy who did not achieve therapeutic targets. Subjects were assessed to receive an additional antidiabetic agent to optimize glucose control; dipeptidyl peptidase-4 inhibitor (DPP4i, n=14), glucagon like peptide-1 receptor agonist (GLP1RA, n=21), sodium/glucose cotransporter-2 inhibitor (SGLT2i, n=21) or long-acting insulin (n=8). Glycosylated hemoglobin (HbA1c) as well as carotid-femoral pulse wave velocity (PWV) and augmentation index (Alx) were measured (as indices of arterial stiffness) were measured at baseline and 3 months after treatment intensification.

Results

There were no differences between the study groups in traditional risk factors, or baseline HbA1c, PWV and Alx levels (p=NS for all). All groups achieved better glycemic control in terms of HbA1c values between baseline and follow-up (for DPP4i: 7.4±0.2% vs 6.7±0.2%, for GLP1RA: 8.3±0.2% vs 6.9±0.1%, for SGLT2i: 7.5±0.1% vs 6.7±0.1% and for insulin 9.8±0.5% vs 7.7±0.4%, p<0.001 for all). PWV decreased from 10.0±0.84 to 9.1±0.43 m/sec (p=0.092) in the DPP4i group, from 11.7±0.72 to 10.2±0.74 m/sec (p<0.001) in the GLP1RA group, from 1.3±0.54 to 9.6±0.59 m/sec (p=0.001) in the SGLT2i group and from 11.6±1.04 to 11.1±1.02 m/sec (p=0.219) in the insulin group. Alx was also decreased from 34.2±1.89 to 31.5±2.17% (p=0.023) in the DPP4i group, from 29.1±1.52 to 25.6±2.09% (p<0.001) in the GLP1RA group, from 29.9±1.44 to 24.2±1.48% (p<0.001) in SGLT2i group, and from 28.2±2.33 to 26.2±1.64% (p=0.153) in insulin group.

Conclusions

These preliminary data provide evidence that treatment intensification -particularly with GLP1RA, and SGLT2i- benefits vascular properties, a finding which could partly explain the positive findings of recent randomized clinical trails in this field.

Acknowledgement/Funding

None

P2481The effect of DPP-4i, GLP-1RA, SGLT-2i and long-acting insulin on platelet function in patients with type 2 diabetes mellitus

Background

Patients with type 2 diabetes mellitus (T2DM) are at higher risk for thrombotic events. Platelet function may be used to assess prothrombotic state in patients with cardiovascular disease.

Purpose

We aimed to investigate whether the administration of novel antidiabetic agents influence platelet function in TDM2 patients.

Patients and methods

We 60 enrolled consecutive patients with T2DM, on stable antidiabetic therapy, who did not achieve therapeutic targets. Subjects were assessed to receive an additional anti-diabetic agent; dipeptidyl peptidase-4 inhibitor (DPP4i, n=14), glucagon like peptide-1 receptor agonist (GLP1RA, n=24), sodium/glucose cotransporter-2 inhibitor (SGLT2i, n=22). Platelet reactivity was measured with PFA-200 collagen/epinephrine (c-EPI) and PFA-200 collagen/ADP (c-ADP) closure time. Glycosylated hemoglobin (HbA1c), c-EPI and c-ADP were assessed at baseline and 3 months after treatment intensification.

Results

There was no difference between the study groups regarding gender, age, hypertension, dyslipidemia, smoking, Hba1c and CADP or CEPI (p=NS for all) at baseline. All groups achieved better glycemic control in terms of HbA1c values between baseline and follow-up (for DPP4i: 7.4±0.2% vs 6.7±0.2%, for GLP1RA: 8.3±0.2% vs 6.9±0.1%, for SGLT2i: 7.5±0.1% vs 6.7±0.1% and for insulin 9.8±0.5% vs 7.7±0.4%, p<0.001 for all). After a 3 month-period, treatment intensification with these novel agents did not influence c-EPI and c-ADP values [155.4±6.64 sec vs 152.9±8.28 sec (p=0.678) and 106.6±4.30 sec vs 106.8±3.93 sec (p=0.955) respectively] in whole population. In subgroup analysis, for patients off antiplatelet treatment (n=31), c-EPI was significantly decreased from 148.4±8.5 to 129.8±13.9 sec (p=0.036), but not c-ADP (from 105.4±5.3 to 99.3±4.9 sec, p=0.094). In patients who did receive antiplatelets (n=37), c-EPI and c-ADP were not significantly changed (c-EPI 163.1±10.9 to 179.6±13.9 sec p=0.201 and c-ADP from 106.6±8.2 sec to 114.6±7.3 sec, p=0.318) respectively.

Conclusion

Antiplatelet treatment prevents thrombotic risk in T2DM patients receiving novel antidiabetics. The effects of novel antidiabetics on platelet reactivity -as well as any distinct class properties- merits further investigation.

Acknowledgement/Funding

None

4099High intensity endurance and strength training in water polo Olympic team players: impact on arterial wall properties

Background

Regular physical activity is recommended for health improvement. However the upper intensity threshold associated with best health outcome is difficult to determine. Water polo (WP) Olympic athletes present unique characteristics with very high intensity work, long training sessions and a combination of endurance and strength training.

Purpose

To examine how long term, intense mixed endurance and strength training affect peripheral and central hemodynamics and biomarkers of cardiovascular health.

Methods

The study population consisted of 20 WP Olympic team player's, 20 matched recreational active subjects (RA) and 20 sedentary control subjects (Cl). Reflected waves were assessed with the Augmentation index (AIx), central aortic stiffness with pulse wave velocity (PWV) and endothelial function with flow mediated dilation (FMD).

Results

From Cl subjects to RA active subjects and to WP players there was a stepwise decrease in aortic systolic pressure (116±16 mmHg vs. 107±14 mmHg vs. 106±6 mmHg, p=0.03) while there was no difference in branchial systolic pressure (p=0.52). There was also a stepwise improvement in AIx (−4.22±9.97% vs. −6.97±11.28% vs. −12.14±6.62%, p=0.03) and FMD (6.61±1.78% vs. 7.78±1.98% vs. 8.3±2.05%, p=0.04) according to the intensity of exercise and WP players had lower AIx and higher FMD compared to RA subjects and to Cl subjects.

Conclusions

In young WP Olympic team players intense mixed endurance and strength training has no adverse impact on arterial wall properties and endothelial function with a parallel improvement in central hemodynamics. These findings highlight that there are no definitive data to support on any adverse vascular related impact of ultra-endurance training while mixed endurance and strength training may be associated with a favorable vascular profile.

Serum IgA1 shows increased levels of α2,6-linked sialic acid in breast cancer

The lectin Helix pomatia agglutinin (HPA) recognizes altered glycosylation in solid cancers and the identification of HPA binding partners in tumour tissue and serum is an important aim. Among the many HPA binding proteins, IgA1 has been reported to be the most abundant in liver metastases. In this study, the glycosylation of IgA1 was evaluated using serum samples from patients with breast cancer (BCa) and the utility of IgA1 glycosylation as a biomarker was assessed. Detailed mass spectrometric structural analysis showed an increase in disialo-biantennary N-linked glycans on IgA1 from BCa patients (p < 0.0001: non-core fucosylated; p = 0.0345: core fucosylated) and increased asialo-Thomsen-Friedenreich antigen (TF) and disialo-TF antigens in the O-linked glycan preparations from IgA1 of cancer patients compared with healthy control individuals. An increase in Sambucus nigra binding was observed, suggestive of increased α2,6-linked sialic acid on IgA1 in BCa. Logistic regression analysis showed HPA binding to IgA1 and tumour size to be significant independent predictors of distant metastases (χ ² 13.359; n = 114; p = 0.020) with positive and negative predictive values of 65.7% and 64.6%, respectively. Immunohistochemical analysis of tumour tissue samples showed IgA1 to be detectable in BCa tissue. This report provides a detailed analysis of serum IgA1 glycosylation in BCa and illustrates the potential utility of IgA1 glycosylation as a biomarker for BCa prognostication.

Human B Cell Differentiation Is Characterized by Progressive Remodeling of O-Linked Glycans

Germinal centers (GC) are microanatomical niches where B cells proliferate, undergo antibody affinity maturation, and differentiate to long-lived memory B cells and antibody-secreting plasma cells. For decades, GC B cells have been defined by their reactivity to the plant lectin peanut agglutinin (PNA), which binds serine/threonine (O-linked) glycans containing the asialylated disaccharide Gal-β1,3-GalNAc-Ser/Thr (also called T-antigen). In T cells, acquisition of PNA binding by activated T cells and thymocytes has been linked with altered tissue homing patterns, cell signaling, and survival. Yet, in GC B cells, the glycobiological basis and significance of PNA binding remains surprisingly unresolved. Here, we investigated the basis for PNA reactivity of GC B cells. We found that GC B cell binding to PNA is associated with downregulation of the α2,3 sialyltransferase, ST3GAL1 (ST3Gal1), and overexpression of ST3Gal1 was sufficient to reverse PNA binding in B cell lines. Moreover, we found that the primary scaffold for PNA-reactive O-glycans in B cells is the B cell receptor-associated receptor-type tyrosine phosphatase CD45, suggesting a role for altered O-glycosylation in antigen receptor signaling. Consistent with similar reports in T cells, ST3Gal1 overexpression in B cells in vitro induced drastic shortening in O-glycans, which we confirmed by both antibody staining and mass spectrometric O-glycomic analysis. Unexpectedly, ST3Gal1-induced changes in O-glycan length also correlated with altered binding of two glycosylation-sensitive CD45 antibodies, RA3-6B2 (more commonly called B220) and MEM55, which (in humans) have previously been reported to favor binding to naïve/GC subsets and memory/plasmablast subsets, respectively. Analysis of primary B cell binding to B220, MEM55, and several plant lectins suggested that B cell differentiation is accompanied by significant loss of O-glycan complexity, including loss of extended Core 2 O-glycans. To our surprise, decreased O-glycan length from naïve to post-GC fates best correlated not with ST3Gal1, but rather downregulation of the Core 2 branching enzyme GCNT1. Thus, our data suggest that O-glycan remodeling is a feature of B cell differentiation, dually regulated by ST3Gal1 and GCNT1, that ultimately results in expression of distinct O-glycosylation states/CD45 glycoforms at each stage of B cell differentiation.

Thioglycosides Are Efficient Metabolic Decoys of Glycosylation that Reduce Selectin Dependent Leukocyte Adhesion

Metabolic decoys are synthetic analogs of naturally occurring biosynthetic acceptors. These compounds divert cellular biosynthetic pathways by acting as artificial substrates that usurp the activity of natural enzymes. While O-linked glycosides are common, they are only partially effective even at millimolar concentrations. In contrast, we report that N-acetylglucosamine (GlcNAc) incorporated into various thioglycosides robustly truncate cell surface N- and O-linked glycan biosynthesis at 10-100 μM concentrations. The >10-fold greater inhibition is in part due to the resistance of thioglycosides to hydrolysis by intracellular hexosaminidases. The thioglycosides reduce β-galactose incorporation into lactosamine chains, cell surface sialyl Lewis-X expression, and leukocyte rolling on selectin substrates including inflamed endothelial cells under fluid shear. Treatment of granulocytes with thioglycosides prior to infusion into mouse inhibited neutrophil homing to sites of acute inflammation and bone marrow by ∼80%-90%. Overall, thioglycosides represent an easy to synthesize class of efficient metabolic inhibitors or decoys. They reduce N-/O-linked glycan biosynthesis and inflammatory leukocyte accumulation.

The mucinous domain of pancreatic carboxyl-ester lipase (CEL) contains core 1/core 2 O-glycans that can be modified by ABO blood group determinants

Carboxyl-ester lipase (CEL) is a pancreatic fat-digesting enzyme associated with human disease. Rare mutations in the CEL gene cause a syndrome of pancreatic exocrine and endocrine dysfunction denoted MODY8, whereas a recombined CEL allele increases the risk for chronic pancreatitis. Moreover, CEL has been linked to pancreatic ductal adenocarcinoma (PDAC) through a postulated oncofetal CEL variant termed feto-acinar pancreatic protein (FAPP). The monoclonal antibody mAb16D10 was previously reported to detect a glycotope in the highly O-glycosylated, mucin-like C terminus of CEL/FAPP. We here assessed the expression of human CEL in malignant pancreatic lesions and cell lines. CEL was not detectably expressed in neoplastic cells, implying that FAPP is unlikely to be a glycoisoform of CEL in pancreatic cancer. Testing of the mAb16D10 antibody in glycan microarrays then demonstrated that it recognized structures containing terminal GalNAc-α1,3(Fuc-α1,2)Gal (blood group A antigen) and also repeated protein sequences containing GalNAc residues linked to Ser/Thr (Tn antigen), findings that were supported by immunostainings of human pancreatic tissue. To examine whether the CEL glycoprotein might be modified by blood group antigens, we used high-sensitivity MALDI-TOF MS to characterize the released O-glycan pool of CEL immunoprecipitated from human pancreatic juice. We found that the O-glycome of CEL consisted mainly of core 1/core 2 structures with a composition depending on the subject's FUT2 and ABO gene polymorphisms. Thus, among digestive enzymes secreted by the pancreas, CEL is a glycoprotein with some unique characteristics, supporting the view that it could serve additional biological functions to its cholesteryl esterase activity in the duodenum.

Loss of GCNT2/I-branched glycans enhances melanoma growth and survival

Cancer cells often display altered cell-surface glycans compared to their nontransformed counterparts. However, functional contributions of glycans to cancer initiation and progression remain poorly understood. Here, from expression-based analyses across cancer lineages, we found that melanomas exhibit significant transcriptional changes in glycosylation-related genes. This gene signature revealed that, compared to normal melanocytes, melanomas downregulate I-branching glycosyltransferase, GCNT2, leading to a loss of cell-surface I-branched glycans. We found that GCNT2 inversely correlated with clinical progression and that loss of GCNT2 increased melanoma xenograft growth, promoted colony formation, and enhanced cell survival. Conversely, overexpression of GCNT2 decreased melanoma xenograft growth, inhibited colony formation, and increased cell death. More focused analyses revealed reduced signaling responses of two representative glycoprotein families modified by GCNT2, insulin-like growth factor receptor and integrins. Overall, these studies reveal how subtle changes in glycan structure can regulate several malignancy-associated pathways and alter melanoma signaling, growth, and survival.

Galectin-9 suppresses B cell receptor signaling and is regulated by I-branching of N-glycans

Leukocytes are coated with a layer of heterogeneous carbohydrates (glycans) that modulate immune function, in part by governing specific interactions with glycan-binding proteins (lectins). Although nearly all membrane proteins bear glycans, the identity and function of most of these sugars on leukocytes remain unexplored. Here, we characterize the N-glycan repertoire (N-glycome) of human tonsillar B cells. We observe that naive and memory B cells express an N-glycan repertoire conferring strong binding to the immunoregulatory lectin galectin-9 (Gal-9). Germinal center B cells, by contrast, show sharply diminished binding to Gal-9 due to upregulation of I-branched N-glycans, catalyzed by the β1,6-N-acetylglucosaminyltransferase GCNT2. Functionally, we find that Gal-9 is autologously produced by naive B cells, binds CD45, suppresses calcium signaling via a Lyn-CD22-SHP-1 dependent mechanism, and blunts B cell activation. Thus, our findings suggest Gal-9 intrinsically regulates B cell activation and may differentially modulate BCR signaling at steady state and within germinal centers.

IL-6 is associated to IGF-1Ec upregulation and Ec peptide secretion, from prostate tumors

Background

Ec peptide (PEc), resulting from the proteolytic cleavage of the IGF-1Ec isoform, is involved in prostate cancer progression and metastasis, whereas in muscle tissue, it is associated with the mobilization of satellite cells prior to repair. Our aim is to determine the physiological conditions associated to the IGF-1Ec upregulation and PEc secretion in prostate tumors, as well as, the effect of tumor PEc on tumor repair.

Methods

IGF-1 (mature and isoforms) expression was examined by qRT-PCR, both in prostate cancer cells co-incubated with cells of the immune response (IR) and in tumors. PEc secretion was determined by Multiple Reaction Monitoring.

The effect of PEc, on mesenchymal stem cell (MSC) mobilization and repair, was examined using migration and invasion assays, FISH and immunohistochemistry (IHC). The JAK/STAT signaling pathway leading to the IGF1-Ec expression was examined by western blot analysis. Determination of the expression and localization of IL-6 and IGF-1Ec in prostate tumors was examined by qRT-PCR and by IHC.

Results

We documented that IL-6 secreted by IR cells activates the JAK2 and STAT3 pathway through IL-6 receptor in cancer cells, leading to the IGF-1Ec upregulation and PEc secretion, as well as to the IL-6 expression and secretion. The resulting PEc, apart from its oncogenic role, also mobilizes MSCs towards the tumor, thus promoting tumor repair.

Conclusions

IL-6 leads to the PEc secretion from prostate cancer cells. Apart from its oncogenic role, PEc is also involved in the mobilization of MSCs resulting in tumor repair.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0003-z) contains supplementary material, which is available to authorized users.