Background: Fatty acids are important dietary factors that have been extensively studied for their implication in health and disease. Evidence from epidemiological studies and randomised controlled trials on their role in cardiovascular, inflammatory, and other diseases remains inconsistent. The objective of this study was to assess whether genetically predicted fatty acid concentrations affect the risk of disease across a wide variety of clinical health outcomes.Methods and findings: The UK Biobank (UKB) is a large study involving over 500,000 participants aged 40 to 69 years at recruitment from 2006 to 2010. We used summary-level data for 117,143 UKB samples (base dataset), to extract genetic associations of fatty acids, and individual-level data for 322,232 UKB participants (target dataset) to conduct our discovery analysis. We studied potentially causal relationships of circulating fatty acids with 845 clinical diagnoses, using mendelian randomisation (MR) approach, within a phenome-wide association study (PheWAS) framework. Regression models in PheWAS were adjusted for sex, age, and the first 10 genetic principal components. External summary statistics were used for replication. When several fatty acids were associated with a health outcome, multivariable MR and MR-Bayesian method averaging (MR-BMA) was applied to disentangle their causal role. Genetic predisposition to higher docosahexaenoic acid (DHA) was associated with cholelithiasis and cholecystitis (odds ratio per mmol/L: 0.76, 95% confidence interval: 0.66 to 0.87). This was supported in replication analysis (FinnGen study) and by the genetically predicted omega-3 fatty acids analyses. Genetically predicted linoleic acid (LA), omega-6, polyunsaturated fatty acids (PUFAs), and total fatty acids (total FAs) showed positive associations with cardiovascular outcomes with support from replication analysis. Finally, higher genetically predicted levels of DHA (0.83, 0.73 to 0.95) and omega-3 (0.83, 0.75 to 0.92) were found to have a protective effect on obesity, which was supported using body mass index (BMI) in the GIANT consortium as replication analysis. Multivariable MR analysis suggested a direct detrimental effect of LA (1.64, 1.07 to 2.50) and omega-6 fatty acids (1.81, 1.06 to 3.09) on coronary heart disease (CHD). MR-BMA prioritised LA and omega-6 fatty acids as the top risk factors for CHD. Although we present a range of sensitivity analyses to the address MR assumptions, horizontal pleiotropy may still bias the reported associations and further evaluation in clinical trials is needed.Conclusions: Our study suggests potentially protective effects of circulating DHA and omega-3 concentrations on cholelithiasis and cholecystitis and on obesity, highlighting the need to further assess them as prevention treatments in clinical trials. Moreover, our findings do not support the supplementation of unsaturated fatty acids for cardiovascular disease prevention.

Background: NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels are variably elevated in heart failure with preserved ejection fraction (HFpEF), even in the presence of increased left ventricular filling pressures. NT-proBNP levels are prognostic in HFpEF and have been used as an inclusion criterion for several recent randomized clinical trials. However, the underlying biologic differences between HFpEF participants with high and low NT-proBNP levels remain to be fully understood. Methods: We measured 4928 proteins using an aptamer-based proteomic assay (SOMAScan) in available plasma samples from 2 cohorts: (1) Participants with HFpEF enrolled in the PHFS (Penn Heart Failure Study; n=253); (2) TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist Trial) participants in the Americas (n=218). We assessed the relationship between SOMAScan-derived plasma NT-proBNP and levels of other proteins available in the SOMAScan assay version 4 using robust linear regression, with correction for multiple comparisons, followed by pathway analysis. Results: NT-proBNP levels exhibited prominent proteome-wide associations in PHFS and TOPCAT cohorts. Proteins most strongly associated with NT-proBNP in both cohorts included SVEP1 (sushi, von Willebrand factor type-A, epidermal growth factor, and pentraxin domain containing 1; β _TOPCAT =0.539; P <0.0001; β _PHFS =0.516; P <0.0001) and ANGPT2 (angiopoietin 2; β _TOPCAT =0.571; P <0.0001; β _PHFS =0.459; P <0.0001). Canonical pathway analysis demonstrated consistent associations with multiple pathways related to fibrosis and inflammation. These included hepatic fibrosis and inhibition of matrix metalloproteases. Analyses using cut points corresponding to estimated quantitative concentrations of 360 pg/mL (and 480 pg/mL in atrial fibrillation) revealed similar proteomic associations. Conclusions: Circulating NT-proBNP levels exhibit prominent proteomic associations in HFpEF. Our findings suggest that higher NT-proBNP levels in HFpEF are a marker of fibrosis and inflammation. These findings will aid the interpretation of NT-proBNP levels in HFpEF and may guide the selection of participants in future HFpEF clinical trials.

Background: The role of cellular senescence in human heart failure (HF) remains unclear. The senescence‐associated secretory phenotype (SASP) is composed of proteins released by senescent cells. We assessed the prognostic significance and biologic pathways associated with the SASP in human HF using a plasma proteomics approach. Methods and Results: We measured 25 known SASP proteins among 2248 PHFS (Penn HF Study) participants using the SOMAScan V4 assay. We extracted the common variance in these proteins to generate SASP factor scores and assessed the relationship between these SASP factor scores and (1) all‐cause death and (2) the composite of death or HF hospital admission. We also assessed the relationship of each SASP factor to 4746 other proteins, correcting for multiple comparisons, followed by pathway analyses. Two SASP factors were identified. Both factors were associated with older age, lower estimated glomerular filtration rate, and more advanced New York Heart Association class, among other clinical variables. Both SASP factors exhibited a significant positive association with the risk of death independent of the Meta‐Analysis of Global‐Group in Chronic HF score and NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) levels. The 2 identified SASP factors were associated with 1201 and 1554 proteins, respectively, belonging to various pathways including the coagulation system, complement system, acute phase response signaling, and retinoid X receptor–related pathways that regulate cell metabolism. Conclusions: Increased SASP components are independently associated with adverse outcomes in HF. Biologic pathways associated with SASP are predominantly related to coagulation, inflammation, and cell metabolism.

BACKGROUND: Iron deficiency (ID) is currently defined as a serum ferritin level <100 or 100 to 299 ng/mL with transferrin saturation (TSAT) <20%. Serum ferritin and TSAT are currently used to define absolute and functional ID. However, individual markers of iron metabolism may be more informative than current arbitrary definitions of ID. METHODS: We assessed prognostic associations of ferritin, serum iron, and TSAT among 2050 participants with heart failure (HF) with reduced/mid-range (n=1821) or preserved (n=229) left ventricular ejection fraction enrolled in the PHFS (Penn HF Study), a prospective cohort study. We measured 4928 plasma proteins using an aptamer-based assay (SOMAScanv4) and assessed prognostic and proteomic associations of markers of iron metabolism. RESULTS: Ferritin concentrations were not associated with outcomes, whereas low TSAT and serum iron were associated with the risk of all-cause death (TSAT: standardized hazard ratio, 0.84 [95% CI, 0.76–0.93]; P =0.001; serum iron: standardized hazard ratio, 0.87 [95% CI, 0.79–0.96]; P =0.007). Similarly, TSAT was associated with the risk of death or HF-related admission (standardized hazard ratio, 0.89 [95% CI, 0.83–0.95]; P =0.0006). Significant interactions between TSAT and HF with preserved ejection fraction status were found such that TSAT was more strongly associated with the risk of death and death or HF-related admission in HF with preserved ejection fraction. We identified 359 proteins associated with TSAT, including TFRC (transferrin receptor protein; β, −0.455; P <0.0001) and CRP (C-reactive protein; β, −0.355; P <0.0001). Pathway analyses demonstrated associations with lipid metabolism, complement activation, and inflammation. In contrast to the robust associations between TSAT and outcomes, ID and absolute ID defined by current criteria were not associated with death or death or HF-related admission. TSAT was associated with outcomes regardless of the presence of functional versus absolute ID. CONCLUSIONS: Low TSAT, but not ferritin concentrations, is significantly associated with adverse outcomes in HF. Low TSAT is more strongly associated with outcomes in HF with preserved ejection fraction. Pathways related to inflammation and lipid metabolism are associated with low TSAT in HF.

Background: Circulating plasma proteins are clinically useful biomarkers for stroke risk. We examined the causal links between plasma proteins and stroke risk in individuals of South Asian ancestry. Methods and Results: We applied proteome‐wide Mendelian randomization and colocalization approaches to understand causality of 2922 plasma proteins on stroke risk in individuals of South Asian ancestry. We obtained genetic instruments (proxies) for plasma proteins from the UK Biobank (N=920). Genome‐wide association studies summary data for strokes (N≤11 312) were sourced from GIGASTROKE consortium. Our primary approach involved the Wald ratio or inverse‐variance‐weighted methods, with statistical significance set at false discovery rate <0.1. Additionally, a Bayesian colocalization approach assessed shared causal variants among proteome, transcriptome, and stroke phenotypes to minimize bias from linkage disequilibrium. We found evidence of a potential causal effect of plasma GP6 (glycoprotein VI) levels on cardioembolic stroke (odds ratio [OR] _{Wald ratio} =2.53 [95% CI, 1.59–4.03]; P =9.2×10 ⁻⁵ , false discovery rate=0.059). Generalized Mendelian randomization accounting for correlated single nucleotide polymorphisms (SNPs), with the P value threshold at P 50%). The potential causal effect of GP6 on cardioembolic stroke was not significant in European populations (OR _{inverse‐variance‐weighted} =1.08 [95% CI, 0.93–1.26]; P =0.29). Conclusions: Our joint Mendelian randomization and colocalization analyses suggest that genetically predicted GP6 is potentially causally associated with cardioembolic stroke risk in individuals of South Asian ancestry. As genetic data on individuals of South Asian ancestry increase, future Mendelian randomization studies with larger sample size for plasma GP6 levels should be implemented to further validate our findings. Additionally, clinical studies will be necessary to verify GP6 as a therapeutic target for cardioembolic stroke in South Asians.

Background: Identifying novel molecular drivers of disease progression in heart failure (HF) is a high‐priority goal that may provide new therapeutic targets to improve patient outcomes. The authors investigated the relationship between plasma proteins and adverse outcomes in HF and their putative causal role using Mendelian randomization. Methods and Results: The authors measured 4776 plasma proteins among 1964 participants with HF with a reduced left ventricular ejection fraction enrolled in PHFS (Penn Heart Failure Study). Assessed were the observational relationship between plasma proteins and (1) all‐cause death or (2) death or HF‐related hospital admission (DHFA). The authors replicated nominally significant associations in the Washington University HF registry (N=1080). Proteins significantly associated with outcomes were the subject of 2‐sample Mendelian randomization and colocalization analyses. After correction for multiple testing, 243 and 126 proteins were found to be significantly associated with death and DHFA, respectively. These included small ubiquitin–like modifier 2 (standardized hazard ratio [sHR], 1.56; P <0.0001), growth differentiation factor‐15 (sHR, 1.68; P <0.0001) for death, A disintegrin and metalloproteinase with thrombospondin motifs–like protein (sHR, 1.40; P <0.0001), and pulmonary‐associated surfactant protein C (sHR, 1.24; P <0.0001) for DHFA. In pathway analyses, top canonical pathways associated with death and DHFA included fibrotic, inflammatory, and coagulation pathways. Genomic analyses provided evidence of nominally significant associations between levels of 6 genetically predicted proteins with DHFA and 11 genetically predicted proteins with death. Conclusions: This study implicates multiple novel proteins in HF and provides preliminary evidence of associations between genetically predicted plasma levels of 17 candidate proteins and the risk for adverse outcomes in human HF.