Novel biomarkers predict ablation outcomes in long stranding persistent atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR

Background

Ablation of long-standing persistent atrial fibrillation (LSPAF) is not always successful. The arrhythmia burden was reduced by 75% by 12 months in majority (72%) of patients with LSPAF who underwent surgical or percutaneous ablation in the CASA-AF trial. We hypothesised that biomarker(s) improve prediction of clinical success and offer insights into mechanisms.

Objective

To identify biomarkers that predict success (75% arrhythmia burden reduction) after ablation for LSPAF at 12-months.

Methods

Amongst patients participating in the CASA-AF RCT (ISRCTN18250790), pre-ablation serum samples were selected for 20 patients who met criteria for ablation-success at 12 months, and 20 who did not. Olink ProteomicsTM (Sweden) provided analyses using three biomarker panels [inflammation (INFL), cardiovascular III (CVD III), and cell cytology (CELL)] each containing 92 biomarkers. Univariate and multivariable analyses were adjusted for age, sex, BMI, LA diameter and CRP. ROC analysis was undertaken to assess the diagnostic accuracy of the biomarkers. To counter the false discovery rate, Benjamini-Hochberg correction was utilised.

Results

When patients with ablation-success and -failure were compared, no differences in demographics or cardiac function were found. On univariate analysis, several biomarkers in each panel were associated with ablation-success. Multivariable analysis narrowed the range of biomarkers and identified those that were jointly predictive of outcome: INFL (MCP1 + CD8A + CD40, Figure 1), CVD III (FAS + CPB1) and CELL (GCG + ENTPD6 + IL17RB). These joint biomarkers were analysed using ROC (Figure 2), which showed that increases of biomarkers on the INFL panel (MCP1 + CD8A + CD40) were associated with a greater risk of failure and achieved the highest AUC for prediction of outcome [0.82 (0.75-0.87)].

Conclusion

The increase in the serum concentration of markers of inflammation (MCP1 + CD8A + CD40) might be used to identify patients less likely to have sustained benefit from LSPAF ablation. Further studies are required to confirm their prognostic value as pre-procedural biomarkers.

Skin exposome science in practice : current evidence on hair biomonitoring and future perspectives

The skin exposome, defined as the totality of environmental exposures from conception to death that can induce or modify various skin conditions, compiles environmental, lifestyle and psychosocial exposures, as well as the resulting internal biological and physiological responses to these exposures. Biomonitoring can be used to obtain information on the internal dose of pollutants. The concentration of biomarkers in body fluids is highly variable over time due to differential elimination kinetics of chemicals, whereas they accumulate in hair. Hair analysis thus provides information on cumulative exposure over a longer period of time, and so can be used for assessing chronic exposure to pollutants. Studies on hair samples collected from 204 women living in two cities in China with different levels of pollution demonstrated that hair damage and the skin microbiome are biomarkers of a polluted city and long-term exposure to pollution and UV can increase signs of facial ageing. Adopting an exposome approach to skin health requires assessing multiple exposures and biological consequences, possibly in relation to longitudinally followed-up health outcomes. Leveraging "omics" data (e.g. metabolomics, proteomics, genomics and microbiome) and big data analytics, in particular multivariate analysis, will help to further understand the impact of pollution on skin and the combined effects with other exposome factors, including solar radiation and other environmental exposures.

Exploring the relation between socioeconomic position and DNA methylation in a European population

Background

Previous investigations have reported that adverse socioeconomic circumstances across the life-course lead to the alteration of major biological processes, eventually resulting in a higher disease risk and premature death. In particular, a low life-course socioeconomic position (SEP) has been associated with a modified epigenetic signature of loci involved in inflammation, the physiological response to stress, and other regulatory processes.

Methods

In this study, we investigated the association between nine indicators of SEP across the life-course and the differential methylation of 451'000 genome-wide CpG markers, using data from 690 adults included in a Swiss population-based study. We further examined the interrelations between the SEP-related CpGs, and the biological pathways in which the identified markers are involved.

Results

Three SEP indicators in adulthood were associated the differential methylation of 161 genome-wide CpG markers, whereby 156 CpGs were less methylated in people with low versus high SEP. Among the identified CpGs, a substantial proportion of markers were no longer associated with SEP upon accounting for health behaviors and cardiometabolic disorders. In addition, the identified CpGs were found to be involved in immune, inflammatory, and cancer-related processes.

Conclusions

Our results support the hypothesis that adverse socioeconomic circumstances may lead to the dysregulation of inflammatory processes, eventually resulting in the occurrence of serious chronic conditions such as atherosclerosis, diabetes, or cancer.

Key messages

Socioeconomic position is a major determinant of health-related outcomes. Epigenetic modifications may constitute a biological mechanism through which socioeconomic circumstances affect health.

Early life socioeconomic position and adult systemic inflammation: the role of gene regulation

Background

Adverse socioeconomic conditions in childhood affect systemic low-grade inflammation in adulthood. Studies in animals and humans suggest that socioeconomic conditions get under the skin from early life thus contributing to shape pro-inflammatory phenotypes. Although the existence of socioeconomic differences in gene regulation of the immune function have been described previously, no study has so far assessed the extent to which these differences actually explain socioeconomic variations in inflammatory markers.

Methods

First, we ran 2-sample Mendelian Randomization (MR) methods to identify putative genes whose expression drives C-reactive protein (CRP) levels in blood. We used two databases with summary statistics of associations between single nucleotide polymorphisms and gene expression (eQTLGen, N = 31,486 individuals) and CRP (CHARGE, N = 148,164 individuals) in blood. We tested 10,701 genes and retained those with FDR<0.05. Second, we used individual-participant data from a Swiss population-based study (SKIPOGH, N = 723) to estimate the proportion of the effect of paternal occupational position (SEP) on low-grade inflammation in adulthood (CRP>3mg/L) mediated by the selected genes. We estimated odds ratios and mediated proportions through counterfactual-based mediation models.

Results

We identified 426 genes driving CRP levels (robust to unmeasured confounding thanks to MR). They jointly mediated the effect of low father’s occupation on inflammation in adulthood for a proportion up to about 70% [95% confidence intervals (CI) 11-90%] and with an odds ratio of 1.53 [95% CI 1.05-2.15] compared to individuals with high paternal SEP. Analysis of the effects of life-course SEP trajectories (upward, downward and stable low from paternal to adult SEP) on gene regulation revealed trajectory dependent effects.

Conclusions

We suggest that adverse childhood SEP affects systemic inflammation in adulthood through a long-lasting effect on gene regulation.

Social patterning of inflammation over the lifecourse and its relationship with mortality

Background

This study explores (i) the relationship between socioeconomic position (SEP) across the life course and circulating C-reactive protein (CRP), a marker of systemic inflammation, in 6 European cohort studies (in up to N = 23 008) participating in the Lifepath project and (ii) interrogate the hypothesis of a cumulative biological risk (allostatic load, AL) reflecting 4 physiological systems, including inflammation, potentially predicting future risk of death in one of the cohort.

Methods

First, we estimated the association between measures of three time point SEP and adulthood CRP, adjusting for health behaviours and body mass index (BMI). To mimic life course experiences, we sequentially adjusted for the chronologically ordered measures of SEP. Next we used mortality data from the 1958 British birth cohort to operationalise AL from 14 biomarkers collected at age 44. Multivariate Cox proportional hazards regression was used to estimate hazard ratios for the association between AL, biological sub-scores and individual biomarkers with mortality.

Results

Educational attainment was most strongly related to inflammation where low educational attainment was associated with higher log-transformed levels of CRP (β = 0.30, (0.22-0.38)). Higher AL at 44 years old was a significant predictor of mortality 11 years later (HR = 3.56 (2.3 to 5.53)). Among the four physiological systems, only the immune-inflammatory and cardiovascular sub-scores were significantly related to mortality.

Conclusions

Socioeconomic circumstances across the life course are associated with higher levels of inflammation in adulthood which in turn predict subsequent risk of death. But our findings also suggest that the cumulative AL measure consisting of all the biomarkers was a better measure for predicting death adding evidence on the biological embodiment in response to chronic stress, suggesting that social-to-biological processes are at play, beyond the impact of health behaviours and BMI.

A socially patterned Biological Health Score and mortality in Understanding Society and UKBiobank

Background

It now established that social factors impact the quality of ageing, through the lifecourse stimulation/dysregulation of key physiological systems. Composite scores such as allostatic load, focusing on the response to stress, can be used to measure individual physiological wear-and-tear.

Methods

Using data from the Understanding Society study, a cross-sectional panel study including 9,088 participants representative of the UK population, we defined a synthetic biological health score (BHS) capturing the wear-and-tear of four physiological systems (endocrine, inflammatory, cardiovascular, and metabolic systems), and of two key organs (liver and kidney). We used 16 established blood-derived biomarkers of these systems to calculate the BHS and explored the relative contribution of socio-economic position to the BHS and its main components across age groups. Using data from UK biobank, including over 400,000 UK participants in whom similar biomarkers have been assayed in blood, we sought validation of our results and investigated the role of the BHS on all-cause and disease specific mortality, and disease incidence.

Results

We identified a systematic decreasing education-related gradient of the BHS (p < 0·001) leading to lower biological risk in participants with higher educational attainment. Education-related differences in the BHS were detected early in life, and were not attributable to lifestyle and behavioural factors. Analyses of the UK biobank data validated these findings and also showed that the BHS contributed in turn, irrespective of established health risk factors, to all-cause and disease specific mortality.

Interpretation

Our findings highlight the social-to-biological processes ultimately leading to health inequalities, and suggest that such disparities can already be detected in the 20-40 year age group.

The exposome in practice: Design of the EXPOsOMICS project

EXPOsOMICS is a European Union funded project that aims to develop a novel approach to the assessment of exposure to high priority environmental pollutants, by characterizing the external and the internal components of the exposome. It focuses on air and water contaminants during critical periods of life. To this end, the project centres on 1) exposure assessment at the personal and population levels within existing European short and long-term population studies, exploiting available tools and methods which have been developed for personal exposure monitoring (PEM); and 2) multiple "omic" technologies for the analysis of biological samples (internal markers of external exposures). The search for the relationships between external exposures and global profiles of molecular features in the same individuals constitutes a novel advancement towards the development of "next generation exposure assessment" for environmental chemicals and their mixtures. The linkage with disease risks opens the way to what are defined here as 'exposome-wide association studies' (EWAS).

Prediagnostic transcriptomic markers of Chronic lymphocytic leukemia reveal perturbations 10 years before diagnosis

BACKGROUND

B-cell lymphomas are a diverse group of hematological neoplasms with differential etiology and clinical trajectories. Increased insights in the etiology and the discovery of prediagnostic markers have the potential to improve the clinical course of these neoplasms.

METHODS

We investigated in a prospective study global gene expression in peripheral blood mononuclear cells of 263 incident B-cell lymphoma cases, diagnosed between 1 and 17 years after blood sample collection, and 439 controls, nested within two European cohorts.

RESULTS

Our analyses identified only transcriptomic markers for specific lymphoma subtypes; few markers of multiple myeloma (N = 3), and 745 differentially expressed genes in relation to future risk of chronic lymphocytic leukemia (CLL). The strongest of these associations were consistently found in both cohorts and were related to (B-) cell signaling networks and immune system regulation pathways. CLL markers exhibited very high predictive abilities of disease onset even in cases diagnosed more than 10 years after blood collection.

CONCLUSIONS

This is the first investigation on blood cell global gene expression and future risk of B-cell lymphomas. We mainly identified genes in relation to future risk of CLL that are involved in biological pathways, which appear to be mechanistically involved in CLL pathogenesis. Many but not all of the top hits we identified have been reported previously in studies based on tumor tissues, therefore suggesting that a mixture of preclinical and early disease markers can be detected several years before CLL clinical diagnosis.

[Variant Creutzfeldt-Jakob disease in France: estimating the number of cases related to travel to the United Kingdom between 1980 and 1995]

BACKGROUND

The outbreak of variant Creutzfeldt-Jakob disease (vCJD) cases rose serious concerns about secondary transmission of the disease, particularly through blood transfusion. Protective measures leading to the exclusion of potentially infectious blood donors were settled: in France, donors who had stayed more than one year in the UK were excluded. In this work, which was part of a larger study aiming to estimate the French epidemic of vCJD, the number of vCJD cases who were infected during a trip to the UK was estimated. Those estimates may notably enable the assessment of such exclusion measures.

METHODS

The particular age-related structure in vCJD cases is taken into account in our simulations considering birth cohorts in the population. The total French exposure is simulated assuming the main source of infection to be dietary through consumption of mechanically recovered meat (MRM) manufactured from British bovine carcasses. Then, using a "back calculation" algorithm, all infected individuals required to produce a consistent epidemic (6 vCJD cases in 2003) was simulated. This study was exclusively focused on the part of the exposure linked to trips (beef MRM consumed in the UK while traveling) and on cases resulting from this exposure.

RESULTS

The influence of exposure linked to trips to the UK was greater in the youngest cohort (6.3% of the total exposure) while it only accounted for 3.3% and 1% in the 1939-69 and in the pre-1939 birth cohorts respectively. Overall, exposure resulting from trips in the UK can be neglected with regards to the exposure linked to the consumption of MRM produced in France from British bovine carcasses. Consequently, French vCJD cases that would have been infected in the UK are very unlikely to occur (median: 0 case, IC 95%: (0-2)). Nevertheless, if such cases occur, they would probably occur in subjects born after 1969 and their onset would take place before 2010. Thus, unlike the situation in BSE-free countries, the causal relationship between travel in the UK and occurrence of vCJD cases cannot be underlined in France, as trips only account for a small part of the French exposure.

CONCLUSION

Since trips in the UK slightly contribute to the overall French exposure, excluding people who travelled in the UK from blood donation would not influence the risk of secondary transmission.