Exploring synaptic pathways in traumatic brain injury: a cross-phenotype genomics approach.

Traumatic brain injury (TBI), a global leading cause of mortality and disability, lacks effective treatments to enhance recovery. Synaptic remodeling has been postulated as one mechanism that influences outcomes after TBI. We sought to investigate whether common mechanisms affecting synapse maintenance are shared between TBI and other neuropsychiatric conditions using pathway enrichment tools and genome-wide genotype data, with the goal of highlighting novel treatment targets. We leveraged an integrative approach, combining data from Genome-Wide Association Studies (GWAS) with pathway and gene-set enrichment analyses. Literature review-based and Reactome database-driven approaches were combined to identify synapse-related pathways of interest in TBI outcome, and to assess for shared associations with conditions in which synapse-related pathobiological mechanisms have been implicated, including Alzheimer's disease (AD), schizophrenia (SCZ), major depressive disorder (MDD), post-traumatic stress disorder (PTSD), attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Gene and pathway-level enrichment analyses were conducted using MAGMA and its extensions, e- and H-MAGMA, followed by Mendelian Randomization (MR) to investigate potential causal associations. Of the 98 pathways tested, 32 were significantly enriched in the included conditions. In TBI outcome, we identified significant enrichment in five pathways: "Serotonin clearance from the synaptic cleft" (p-value = 0.0001), "Presynaptic nicotinic acetylcholine receptors" (p-value = 0.0003), "Postsynaptic nicotinic acetylcholine receptors" (p-value = 0.0003), "Highly sodium permeable postsynaptic acetylcholine nicotinic receptors" (p-value = 0.0001), and "Acetylcholine binding and downstream events" pathways (p-value = 0.0003). These associations highlight potential involvement of the cholinergic and serotonergic systems in post-TBI recovery. Three of those pathways were shared between TBI and schizophrenia, suggesting possible pathophysiologic commonalities. In this study we utilize comparative and integrative genomic approaches across brain conditions that share synaptic mechanisms to explore the pathophysiology of TBI outcome. Our results implicate associations between TBI outcome and synaptic pathways as well as pathobiologic overlap with other neuropsychiatric diseases.

Translating Anti-Inflammatory Strategies for Atherosclerosis: Deep Phenotyping, Next-Generation Drug Targets, and Precision Medicine.

Atherosclerosis is the main pathology underlying cardiovascular disease (CVD), including myocardial infarction and ischemic stroke [...].

The role of the gluteofemoral adipose tissue in cerebrovascular disease risk: evidence from a mendelian randomization and mediation analysis.

Objective: To explore causal associations between BMI-independent body fat distribution profiles and cerebrovascular disease risk, and to investigate potential mediators underlying these associations. Methods: Leveraging data from genome wide association studies of BMI-independent gluteofemoral (GFAT), abdominal subcutaneous (ASAT), and visceral (VAT) adipose tissue volumes in UK Biobank, we selected variants associated with each trait, and performed univariable and multivariable mendelian randomization (MR) analyses on ischemic stroke and subtypes (large artery (LAS), cardioembolic (CES), small vessel (SVS)). We used coronary artery disease (CAD), carotid intima media thickness (cIMT), and an MRI-confirmed lacunar stroke as positive controls. For significant associations, we explored the mediatory role of four possible mediator categories in mediation MR analyses. Results: Higher genetically proxied, BMI-independent GFAT volume was associated with decreased risk of ischemic stroke (FDR-p=0.0084), LAS (FDR-p=0.019), SVS (FDR-p<0.001), CAD (FDR-p<0.001), MRI-confirmed lacunar stroke (FDR-p=0.0053), and lower mean cIMT (FDR-p=0.0023), but not CES (FDR-p=0.749). Associations were largely consistent in pleiotropy- and sample structure-robust analyses. No association was observed between genetically proxied ASAT or VAT volumes and ischemic stroke/subtypes risk. In multivariable MR analyses, GFAT showed the most consistent independent association with ischemic stroke, LAS, and SVS. Common vascular risk factors were the predominant mediators in the GFAT-cerebrovascular disease axis, while adipose-tissue-specific adiponectin and leptin mediated a proportion of ischemic stroke and CAD risk. Interpretation: Genetically proxied, BMI-independent higher GFAT volume is associated with reduced cerebrovascular disease risk. Although this is largely mediated by common vascular risk factor modification, targeting adipose-tissue specific pathways may provide additional cardiovascular benefit.

DNA-sensing inflammasomes cause recurrent atherosclerotic stroke.

The risk of early recurrent events after stroke remains high despite currently established secondary prevention strategies1. Risk is particularly high in patients with atherosclerosis, with more than 10% of patients experiencing early recurrent events1,2. However, despite the enormous medical burden of this clinical phenomenon, the underlying mechanisms leading to increased vascular risk and recurrent stroke are largely unknown. Here, using a novel mouse model of stroke-induced recurrent ischaemia, we show that stroke leads to activation of the AIM2 inflammasome in vulnerable atherosclerotic plaques via an increase of circulating cell-free DNA. Enhanced plaque inflammation post-stroke results in plaque destabilization and atherothrombosis, finally leading to arterioarterial embolism and recurrent stroke within days after the index stroke. We confirm key steps of plaque destabilization also after experimental myocardial infarction and in carotid artery plaque samples from patients with acute stroke. Rapid neutrophil NETosis was identified as the main source of cell-free DNA after stroke and NET-DNA as the causative agent leading to AIM2 inflammasome activation. Neutralization of cell-free DNA by DNase treatment or inhibition of inflammasome activation reduced the rate of stroke recurrence after experimental stroke. Our findings present an explanation for the high recurrence rate after incident ischaemic events in patients with atherosclerosis. The detailed mechanisms uncovered here provide clinically uncharted therapeutic targets for which we show high efficacy to prevent recurrent events. Targeting DNA-mediated inflammasome activation after remote tissue injury represents a promising avenue for further clinical development in the prevention of early recurrent events.

Genetically proxied IL-6 signaling and risk of Alzheimer's disease and lobar intracerebral hemorrhage: A drug target Mendelian randomization study.

INTRODUCTION: Evidence suggests that higher C-reactive protein (CRP) is associated with lower risk of Alzheimer's disease (AD) and lobar intracerebral hemorrhage (ICH). Whether interleukin (IL)-6 signaling, an active pharmacological target upstream of CRP, is associated with these amyloid-related pathologies remains unknown. METHODS: We used 26 CRP-lowering variants near the IL-6 receptor gene to perform Mendelian randomization analyses for AD (111,326 cases, 677,663 controls) and ICH (1545 cases, 1481 controls). We explored the effect of genetically proxied IL-6 signaling on serum, cerebrospinal fluid (CSF), and brain proteome (971 individuals). RESULTS: Genetically upregulated IL-6 receptor-mediated signaling was associated with lower risk of AD (OR per increment in serum logCRP levels: 0.87, 95% CI: 0.79-0.95) and lobar ICH (OR: 0.27, 95% CI: 0.09-0.89). We also found associations with 312, 77, and 79 brain, CSF, and plasma proteins, respectively, some of which were previously implicated in amyloid-clearing mechanisms. DISCUSSION: Genetic data support that CRP-lowering through variation in the gene encoding IL-6 receptor may be associated with amyloid-related outcomes. Highlights: Genetic variants proxying IL-6 inhibition are associated with AD and lobar ICH risk.The variants are also associated with amyloid clearing-related proteomic changes.Whether pharmacologic IL-6 inhibition is linked to AD or lobar ICH merits further study.

Genetically proxied HTRA1 protease activity and circulating levels independently predict risk of ischemic stroke and coronary artery disease.

Genetic variants in HTRA1 are associated with stroke risk. However, the mechanisms mediating this remain largely unknown, as does the full spectrum of phenotypes associated with genetic variation in HTRA1. Here we show that rare HTRA1 variants are linked to ischemic stroke in the UK Biobank and BioBank Japan. Integrating data from biochemical experiments, we next show that variants causing loss of protease function associated with ischemic stroke, coronary artery disease and skeletal traits in the UK Biobank and MyCode cohorts. Moreover, a common variant modulating circulating HTRA1 mRNA and protein levels enhances the risk of ischemic stroke and coronary artery disease while lowering the risk of migraine and macular dystrophy in genome-wide association study, UK Biobank, MyCode and BioBank Japan data. We found no interaction between proxied HTRA1 activity and levels. Our findings demonstrate the role of HTRA1 for cardiovascular diseases and identify two mechanisms as potential targets for therapeutic interventions.

Proteogenomic analyses identify coagulation factor XI as a thromboinflammatory mediator of long COVID.

SARS-CoV-2 infection can result in long COVID, characterized by post-acute symptoms from multiple organ systems. Current hypotheses on mechanisms underlying long COVID include persistent inflammation and dysregulated coagulation; however, precise mechanisms and causal mediators remain unclear. Here, we tested the associations of genetic instruments for 49 complement and coagulation factors from the UK Biobank ( N =34,557) with long COVID in the Long COVID Host Genetics Initiative ( N =997,600). Primary analyses revealed that genetically predicted higher factor XI increased long COVID risk (odds ratio, 1.17 [95% confidence interval, 1.08-1.27] per standard deviation; P =1.7×10 -4 ). This association was robust to sensitivity analyses using pleiotropy-robust methods and different genetic instruments and was replicated using proteogenomic data from an Icelandic cohort. Genetically predicted factor XI was also associated with venous thromboembolism, but not with acute COVID-19 or long COVID-resembling conditions. Collectively, these findings provide genetic evidence implicating factor XI in the biology of long COVID.

High-Sensitivity Cardiac Troponin T and Cognitive Function Over 12 Months After Stroke-Results of the DEMDAS Study.

BACKGROUND: Subclinical myocardial injury in form of hs-cTn (high-sensitivity cardiac troponin)  levels has been associated with cognitive impairment and imaging markers of cerebral small vessel disease (SVD) in population-based and cardiovascular cohorts. Whether hs-cTn is associated with domain-specific cognitive decline and SVD burden in patients with stroke remains unknown. METHODS AND RESULTS: We analyzed patients with acute stroke without premorbid dementia from the prospective multicenter DEMDAS (DZNE [German Center for Neurodegenerative Disease]-Mechanisms of Dementia after Stroke) study. Patients underwent neuropsychological testing 6 and 12 months after the index event. Test results were classified into 5 cognitive domains (language, memory, executive function, attention, and visuospatial function). SVD markers (lacunes, cerebral microbleeds, white matter hyperintensities, and enlarged perivascular spaces) were assessed on cranial magnetic resonance imaging to constitute a global SVD score. We examined the association between hs-cTnT (hs-cTn T levels) and cognitive domains as well as the global SVD score and individual SVD markers, respectively. Measurement of cognitive and SVD-marker analyses were performed in 385 and 466 patients with available hs-cTnT levels, respectively. In analyses adjusted for demographic characteristics, cardiovascular risk factors, and cognitive status at baseline, higher hs-cTnT was negatively associated with the cognitive domains "attention" up to 12 months of follow-up (beta-coefficient, -0.273 [95% CI, -0.436 to -0.109]) and "executive function" after 12 months. Higher hs-cTnT was associated with the global SVD score (adjusted odds ratio, 1.95 [95% CI, 1.27-3.00]) and the white matter hyperintensities and lacune subscores. CONCLUSIONS: In patients with stroke, hs-cTnT is associated with a higher burden of SVD markers and cognitive function in domains linked to vascular cognitive impairment. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01334749.

KCNA2 IgG autoimmunity in neuropsychiatric diseases.

BACKGROUND: Autoantibodies against the potassium voltage-gated channel subfamily A member 2 (KCNA2) have been described in a few cases of neuropsychiatric disorders, but their diagnostic and pathophysiological role is currently unknown, imposing challenges to medical practice. DESIGN / METHODS: We retrospectively collected comprehensive clinical and paraclinical data of 35 patients with KCNA2 IgG autoantibodies detected in cell-based and tissue-based assays. Patients' sera and cerebrospinal fluid (CSF) were used for characterization of the antigen, clinical-serological correlations, and determination of IgG subclasses. RESULTS: KCNA2 autoantibody-positive patients (n = 35, median age at disease onset of 65 years, range of 16-83 years, 74 % male) mostly presented with cognitive impairment and/or epileptic seizures but also ataxia, gait disorder and personality changes. Serum autoantibodies belonged to IgG3 and IgG1 subclasses and titers ranged from 1:32 to 1:10,000. KCNA2 IgG was found in the CSF of 8/21 (38 %) patients and in the serum of 4/96 (4.2 %) healthy blood donors. KCNA2 autoantibodies bound to characteristic anatomical areas in the cerebellum and hippocampus of mammalian brain and juxtaparanodal regions of peripheral nerves but reacted exclusively with intracellular epitopes. A subset of four KCNA2 autoantibody-positive patients responded markedly to immunotherapy alongside with conversion to seronegativity, in particular those presenting an autoimmune encephalitis phenotype and receiving early immunotherapy. An available brain biopsy showed strong immune cell invasion. KCNA2 autoantibodies occurred in less than 10 % in association with an underlying tumor. CONCLUSION: Our data suggest that KCNA2 autoimmunity is clinically heterogeneous. Future studies should determine whether KCNA2 autoantibodies are directly pathogenic or develop secondarily. Early immunotherapy should be considered, in particular if autoantibodies occur in CSF or if clinical or diagnostic findings suggest ongoing inflammation. Suspicious clinical phenotypes include autoimmune encephalitis, atypical dementia, new-onset epilepsy and unexplained epileptic seizures.

Mendelian Randomization Applied to Neurology: Promises and Challenges

The Mendelian randomization (MR) paradigm allows for causal inferences to be drawn using genetic data. In recent years, the expansion of well-powered publicly available genetic association data related to phenotypes such as brain tissue gene expression, brain imaging, and neurologic diseases offers exciting opportunities for the application of MR in the field of neurology. In this review, we discuss the basic principles of MR, its myriad applications to research in neurology, and potential pitfalls of injudicious applications. Throughout, we provide examples where MR-informed findings have shed light on long-standing epidemiologic controversies, provided insights into the pathophysiology of neurologic conditions, prioritized drug targets, and informed drug repurposing opportunities. With the ever-expanding availability of genome-wide association data, we project MR to become a key driver of progress in the field of neurology. It is therefore paramount that academics and clinicians within the field are familiar with the approach.

Deep Resequencing of the 1q22 Locus in Non-Lobar Intracerebral Hemorrhage.

OBJECTIVE: Genome-wide association studies have identified 1q22 as a susceptibility locus for cerebral small vessel diseases, including non-lobar intracerebral hemorrhage (ICH) and lacunar stroke. In the present study, we performed targeted high-depth sequencing of 1q22 in ICH cases and controls to further characterize this locus and prioritize potential causal mechanisms, which remain unknown. METHODS: A total of 95,000 base pairs spanning 1q22, including SEMA4A, SLC25A44, and PMF1/PMF1-BGLAP were sequenced in 1,055 spontaneous ICH cases (534 lobar and 521 non-lobar) and 1,078 controls. Firth regression and Rare Variant Influential Filtering Tool analysis were used to analyze common and rare variants, respectively. Chromatin interaction analyses were performed using Hi-C, chromatin immunoprecipitation followed by sequencing, and chromatin interaction analysis with paired-end tag databases. Multivariable Mendelian randomization assessed whether alterations in gene-specific expression relative to regionally co-expressed genes at 1q22 could be causally related to ICH risk. RESULTS: Common and rare variant analyses prioritized variants in SEMA4A 5'-UTR and PMF1 intronic regions, overlapping with active promoter and enhancer regions based on ENCODE annotation. Hi-C data analysis determined that 1q22 is spatially organized in a single chromatin loop, and that the genes therein belong to the same topologically associating domain. Chromatin immunoprecipitation followed by sequencing and chromatin interaction analysis with paired-end tag data analysis highlighted the presence of long-range interactions between the SEMA4A-promoter and PMF1-enhancer regions prioritized by association testing. Multivariable Mendelian randomization analyses demonstrated that PMF1 overexpression could be causally related to non-lobar ICH risk. INTERPRETATION: Altered promoter-enhancer interactions leading to PMF1 overexpression, potentially dysregulating polyamine catabolism, could explain demonstrated associations with non-lobar ICH risk at 1q22, offering a potential new target for prevention of ICH and cerebral small vessel disease. ANN NEUROL 2024;95:325-337.

Genetic variation supports a causal role for valproate in prevention of ischemic stroke.

BACKGROUND: Valproate is a candidate for ischemic stroke prevention due to its anti-atherosclerotic effects in vivo. Although valproate use is associated with decreased ischemic stroke risk in observational studies, confounding by indication precludes causal conclusions. AIMS: We applied Mendelian randomization to determine whether genetic variants that influence seizure response among valproate users associate with ischemic stroke. METHODS: We derived a genetic score for valproate response using genome-wide association data of seizure response after valproate intake from the Epilepsy Pharmacogenomics Consortium. We then tested this score among valproate users of the UK Biobank for association with incident and recurrent ischemic stroke using Cox proportional hazard models. As replication, we tested found associations in an independent cohort of valproate users of the Mass General Brigham Biobank. RESULTS: Among 2150 valproate users (mean 56 years, 54% females), 82 ischemic strokes occurred over a mean 12 year follow-up. Higher valproate response genetic score was associated with higher serum valproate levels (+5.78 µg/ml per 1 standard deviation (SD), 95% confidence interval (CI) (3.45, 8.11)). After adjusting for age and sex, higher valproate response genetic score was associated with lower ischemic stroke risk (hazard ratio (HR) per 1 SD 0.73, 95% CI (0.58, 0.91)) with a halving of absolute risk in the highest compared to the lowest score tertile (4.8% vs 2.5%, p trend = 0.027). Among 194 valproate users with prevalent stroke at baseline, a higher valproate response genetic score was associated with lower recurrent ischemic stroke risk (HR per 1 SD 0.53, 95% CI (0.32, 0.86)) with reduced absolute risk in the highest compared to the lowest score tertile (3/51, 5.9% vs 13/71, 18.3%, p trend = 0.026). The valproate response genetic score was not associated with ischemic stroke among the 427,997 valproate non-users (p = 0.61), suggesting minimal pleiotropy. In 1241 valproate users of the Mass General Brigham Biobank with 99 ischemic stroke events over 6.5 years follow-up, we replicated our observed associations between the valproate response genetic score and ischemic stroke (HR per 1 SD 0.77, 95% CI (0.61, 0.97)). CONCLUSION: These results demonstrate that a genetically predicted favorable seizure response to valproate is associated with higher serum valproate levels and reduced ischemic stroke risk among valproate users, providing causal support for valproate effectiveness in ischemic stroke prevention. The strongest effect was found for recurrent ischemic stroke, suggesting potential dual-use benefits of valproate for post-stroke epilepsy. Clinical trials will be required in order to identify populations that may benefit most from valproate for stroke prevention. DATA ACCESS STATEMENT: UK Biobank participant data are available after approval of a research proposal. The weights of the used genetic scores are available in the Supplemental Tables.

Proteogenomic Data Integration Reveals CXCL10 as a Potentially Downstream Causal Mediator for IL-6 Signaling on Atherosclerosis.

BACKGROUND: Genetic and experimental studies support a causal involvement of IL-6 (interleukin-6) signaling in atheroprogression. Although trials targeting IL-6 signaling are underway, any benefits must be balanced against an impaired host immune response. Dissecting the mechanisms that mediate the effects of IL-6 signaling on atherosclerosis could offer insights about novel drug targets with more specific effects. METHODS: Leveraging data from 522 681 individuals, we constructed a genetic instrument of 26 variants in the gene encoding the IL-6R (IL-6 receptor) that proxied for pharmacological IL-6R inhibition. Using Mendelian randomization, we assessed its effects on 3281 plasma proteins quantified with an aptamer-based assay in the INTERVAL cohort (n=3301). Using mediation Mendelian randomization, we explored proteomic mediators of the effects of genetically proxied IL-6 signaling on coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease. For significant mediators, we tested associations of their circulating levels with incident cardiovascular events in a population-based study (n=1704) and explored the histological, transcriptomic, and cellular phenotypes correlated with their expression levels in samples from human atherosclerotic lesions. RESULTS: We found significant effects of genetically proxied IL-6 signaling on 70 circulating proteins involved in cytokine production/regulation and immune cell recruitment/differentiation, which correlated with the proteomic effects of pharmacological IL-6R inhibition in a clinical trial. Among the 70 significant proteins, genetically proxied circulating levels of CXCL10 (C-X-C motif chemokine ligand 10) were associated with risk of coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease, with up to 67% of the effects of genetically downregulated IL-6 signaling on these end points mediated by decreases in CXCL10. Higher midlife circulating CXCL10 levels were associated with a larger number of cardiovascular events over 20 years, whereas higher CXCL10 expression in human atherosclerotic lesions correlated with a larger lipid core and a transcriptomic profile reflecting immune cell infiltration, adaptive immune system activation, and cytokine signaling. CONCLUSIONS: Integrating multiomics data, we found a proteomic signature of IL-6 signaling activation and mediators of its effects on cardiovascular disease. Our analyses suggest the interferon-γ-inducible chemokine CXCL10 to be a potentially causal mediator for atherosclerosis in 3 vascular compartments and, as such, could serve as a promising drug target for atheroprotection.

Risk factors for cognitive impairment and dementia after stroke: a systematic review and meta-analysis.

BACKGROUND: Cognitive impairment and dementia are highly prevalent among stroke survivors and represent a major burden for patients, carers, and health-care systems. We studied the risk factors for post-stroke cognitive impairment (PSCI) and dementia (PSD) beyond the well established risk factors of age and stroke severity. METHODS: In this systematic review and meta-analysis we conducted a systematic literature search from database inception until Sept 15, 2023. We selected prospective and retrospective cohort studies, post-hoc analyses from randomised controlled trials, and nested case-control studies of patients with acute stroke (ischaemic, haemorrhagic, and transient ischaemic attack), exploring associations between risk factors at baseline and PSCI or PSD over a follow-up period of at least 3 months. Study quality was assessed using the Newcastle-Ottawa quality assessment scale. We calculated pooled relative risks (RRs) with random-effects meta-analyses and performed subgroup, meta-regression, and sensitivity analyses. This study was preregistered with PROSPERO, CRD42020164959. FINDINGS: We identified 162 eligible articles for our systematic review, of which 113 articles (89 studies, 160 783 patients) were eligible for meta-analysis. Baseline cognitive impairment was the strongest risk factor for PSCI (RR 2·00, 95% CI 1·66-2·40) and PSD (3·10, 2·77-3·47). We identified diabetes (1·29, 1·14-1·45), presence or history of atrial fibrillation (1·29, 1·04-1·60), presence of moderate or severe white matter hyperintensities (WMH; 1·51, 1·20-1·91), and WMH severity (1·30, 1·10-1·55, per SD increase) as treatable risk factors for PSCI, independent of age and stroke severity. For PSD, we identified diabetes (1·38, 1·10-1·72), presence of moderate or severe WMH (1·55, 1·01-2·38), and WMH severity (1·61, 1·20-2·14, per SD increase) as treatable risk factors. Additional risk factors included lower educational attainment, previous stroke, left hemisphere stroke, presence of three or more lacunes, brain atrophy, and low baseline functional status. Associations of risk factors with PSD were weaker in studies conducted and published more recently. We found substantial interstudy heterogeneity and evidence of reporting bias. INTERPRETATION: Our results highlight the importance of cognitive impairment in the acute phase after stroke for long-term prediction of PSCI and PSD. Treatable risk factors include diabetes, atrial fibrillation, and markers of cerebral small vessel disease (ie, white matter hyperintensities and lacunes). Future trials should explore these risk factors as potential targets for prevention of PSCI and PSD. FUNDING: German Research Foundation.

Genetically proxied HTRA1 protease activity and circulating levels independently predict risk of ischemic stroke and coronary artery disease.

HTRA1 has emerged as a major risk gene for stroke and cerebral small vessel disease with both rare and common variants contributing to disease risk. However, the precise mechanisms mediating this risk remain largely unknown as does the full spectrum of phenotypes associated with genetic variation in HTRA1 in the general population. Using a family-history informed approach, we first show that rare variants in HTRA1 are linked to ischemic stroke in 425,338 European individuals from the UK Biobank with replication in 143,149 individuals from the Biobank Japan. Integrating data from biochemical experiments on 76 mutations occurring in the UK Biobank, we next show that rare variants causing loss of protease function in vitro associate with ischemic stroke, coronary artery disease, and skeletal traits. In addition, a common causal variant (rs2672592) modulating circulating HTRA1 mRNA and protein levels enhances the risk of ischemic stroke, small vessel stroke, and coronary artery disease while lowering the risk of migraine and age-related macular dystrophy in GWAS and UK Biobank data from > 2,000,000 individuals. There was no evidence of an interaction between genetically proxied HTRA1 activity and levels. Our findings demonstrate a central role of HTRA1 for human disease including stroke and coronary artery disease and identify two independent mechanisms that might qualify as targets for future therapeutic interventions.

Genetic and Nongenetic Components of Stroke Family History: A Population Study of Adopted and Nonadopted Individuals.

Background Genetic and nongenetic factors account for the association of family history with disease risk. Comparing adopted and nonadopted individuals provides an opportunity to disentangle those factors. Methods and Results We examined associations between family history of stroke and heart disease with incident stroke and myocardial infarction (MI) in 495 640 UK Biobank participants (mean age, 56.5 years; 55% women) stratified by childhood adoption status (5747 adoptees). We estimated hazard ratios (HRs) per affected family member, and for polygenic risk scores in Cox models adjusted for baseline age and sex. A total of 12 518 strokes and 23 923 MIs occurred over a 13-year follow-up. In nonadoptees, family history of stroke and heart disease was associated with increased stroke and MI risk, with the strongest association of family history of stroke for incident stroke (HR, 1.16 [95% CI, 1.12-1.19]) and family history of heart disease for incident MI (HR, 1.48 [95% CI, 1.45-1.50]). In adoptees, family history of stroke associated with incident stroke (HR, 1.41 [95% CI, 1.06-1.86]), but family history of heart disease was not associated with incident MI (P>0.5). Polygenic risk scores showed strong disease-specific associations in both groups. In nonadoptees, the stroke polygenic risk score mediated 6% risk between family history of stroke and incident stroke, and the MI polygenic risk score mediated 13% risk between family history of heart disease and incident MI. Conclusions Family history of stroke and heart disease increases risk for their respective conditions. Family history of stroke contains substantial potentially modifiable nongenetic risk, indicating a need for novel prevention strategies, whereas family history of heart disease represents predominantly genetic risk.

Interplay Between Chronic Kidney Disease, Hypertension, and Stroke: Insights From a Multivariable Mendelian Randomization Analysis.

BACKGROUND AND OBJECTIVES: Chronic kidney disease (CKD) increases the risk of stroke, but the extent through which this association is mediated by hypertension is unknown. We leveraged large-scale genetic data to explore causal relationships between CKD, hypertension, and cerebrovascular disease phenotypes. METHODS: We used data from genome-wide association studies of European ancestry to identify genetic proxies for kidney function (CKD diagnosis, estimated glomerular filtration rate [eGFR], and urinary albumin-to-creatinine ratio [UACR]), systolic blood pressure (SBP), and cerebrovascular disease (ischemic stroke and its subtypes and intracerebral hemorrhage). We then conducted univariable, multivariable, and mediation Mendelian randomization (MR) analyses to investigate the effect of kidney function on stroke risk and the proportion of this effect mediated through hypertension. RESULTS: Univariable MR revealed associations between genetically determined lower eGFR and risk of all stroke (odds ratio [OR] per 1-log decrement in eGFR, 1.77; 95% CI 1.31-2.40; p < 0.001), ischemic stroke (OR 1.81; 95% CI 1.31-2.51; p < 0.001), and most strongly with large artery stroke (LAS) (OR 3.00; 95% CI 1.33-6.75; p = 0.008). These associations remained significant in the multivariable MR analysis, controlling for SBP (OR 1.98; 95% CI 1.39-2.82; p < 0.001 for all stroke; OR 2.16; 95% CI 1.48-3.17; p < 0.001 for ischemic stroke; OR 4.35; 95% CI 1.84-10.27; p = 0.001 for LAS), with only a small proportion of the total effects mediated by SBP (6.5% [0.7%-16.8%], 6.6% [0.8%-18.3%], and 7.2% [0.5%-24.8%], respectively). Total, direct and indirect effect estimates were similar across a number of sensitivity analyses (weighted median, MR-Egger regression). DISCUSSION: Our results demonstrate an independent causal effect of impaired kidney function, as assessed by decreased eGFR, on stroke risk, particularly LAS, even when controlled for SBP. Targeted prevention of kidney disease could lower atherosclerotic stroke risk independent of hypertension.

Carriers of rare damaging CCR2 genetic variants are at lower risk of atherosclerotic disease.

Background: The CCL2/CCR2 axis governs monocyte trafficking and recruitment to atherosclerotic lesions. Human genetic analyses and population-based studies support an association between circulating CCL2 levels and atherosclerosis. Still, it remains unknown whether pharmacological targeting of CCR2, the main CCL2 receptor, would provide protection against human atherosclerotic disease. Methods: In whole-exome sequencing data from 454,775 UK Biobank participants (40-69 years), we identified predicted loss-of-function (LoF) or damaging missense (REVEL score >0.5) variants within the CCR2 gene. We prioritized variants associated with lower monocyte count (p<0.05) and tested associations with vascular risk factors and risk of atherosclerotic disease over a mean follow-up of 14 years. The results were replicated in a pooled cohort of three independent datasets (TOPMed, deCODE and Penn Medicine BioBank; total n=441,445) and the effect of the most frequent damaging variant was experimentally validated. Results: A total of 45 predicted LoF or damaging missense variants were identified in the CCR2 gene, 4 of which were also significantly associated with lower monocyte count, but not with other white blood cell counts. Heterozygous carriers of these variants were at a lower risk of a combined atherosclerosis outcome, showed a lower burden of atherosclerosis across four vascular beds, and were at a lower lifetime risk of coronary artery disease and myocardial infarction. There was no evidence of association with vascular risk factors including LDL-cholesterol, blood pressure, glycemic status, or C-reactive protein. Using a cAMP assay, we found that cells transfected with the most frequent CCR2 damaging variant (3:46358273:T:A, M249K, 547 carriers, frequency: 0.14%) show a decrease in signaling in response to CCL2. The associations of the M249K variant with myocardial infarction were consistent across cohorts (ORUKB: 0.62 95%CI: 0.39-0.96; ORexternal: 0.64 95%CI: 0.34-1.19; ORpooled: 0.64 95%CI: 0.450.90). In a phenome-wide association study, we found no evidence for higher risk of common infections or mortality among carriers of damaging CCR2 variants. Conclusions: Heterozygous carriers of damaging CCR2 variants have a lower burden of atherosclerosis and lower lifetime risk of myocardial infarction. In conjunction with previous evidence from experimental and epidemiological studies, our findings highlight the translational potential of CCR2-targeting as an atheroprotective approach.

The ABCD-GENE score influences vascular event rates in both users of clopidogrel and aspirin, as well as non-users of either drug in a population-based cohort study.

Background and Objectives: Clopidogrel is an antiplatelet used in both primary and secondary prevention of cardiovascular diseases. It is a prodrug, requiring CYP2C19 for its metabolism to the active metabolite. The ABCD-GENE score, combining clinical attributes (age, body mass index, chronic kidney disease, diabetes mellitus), with genetic information (presence of 1 or 2 loss of function (LOF) alleles in the CYP2C19 gene) has been shown to identify patients with higher risk of recurrent cardiovascular events in high-risk populations undergoing percutaneous coronary intervention. We aimed to determine if the ABCD-GENE score or LOF alleles were associated with an increased risk of vascular events among clopidogrel users in a general population. Methods: We conducted a population based cohort study with UK Biobank's primary care prescription records to identify clopidogrel users. ABCD-GENE scores were calculated with closest available data from the first date of clopidogrel prescription. The number of LOF alleles present, and the clinical component ABCD, were separate exposures. The outcome of interest was a composite endpoint of vascular events comprised of myocardial infarction, ischemic stroke, and death due to either of these. We performed Cox proportional hazards models with clopidogrel as a time varying exposure to predict hazards of these outcomes. In order to determine the drug specificity of these exposures, the analyses were repeated in aspirin users, and in non-users of either aspirin or clopidogrel. Results: Among 11,248 clopidogrel users, 3,365 (30%) developed a vascular event over a mean follow-up of 5.95±3.94 years. ABCD-GENE score ≥10 was associated with an increased risk of vascular events (HR 1.13, 95% CI 1.03-1.23). In aspirin users, and in non-users of either aspirin or clopidogrel, the ABCD-GENE score was also associated with increased risk of vascular events. In clopidogrel users, aspirin users, and non-users of either drug, the ABCD score was associated with increased risk of vascular events. The presence of two CYP2C19 LOF alleles was associated with an increased risk of vascular events in aspirin and non-users but not in clopidogrel users. Discussion: In this population-based cohort study, the ABCD-GENE score was associated with an increased risk of vascular events in clopidogrel users, aspirin users, and in non-users of either drug. The clinical component, ABCD was also associated with an increased risk of vascular events in all three groups. This suggests that the ABCD-GENE score is not specific to clopidogrel users in identifying persons at high risk of vascular events in a general sample with low baseline CYP2C19 LOF allele frequency.

Genetic and non-genetic components of family history of stroke and heart disease: a population-based study among adopted and non-adopted individuals.

Background: It is increasingly clear that genetic and non-genetic factors account for the association of family history with disease risk in offspring. We sought to distinguish the genetic and non-genetic contributions of family history of stroke and heart disease on incident events by examining adopted and non-adopted individuals. Methods: We examined associations between family history of stroke and heart disease with incident stroke and myocardial infarction (MI) in 495,640 participants of the UK Biobank (mean age 56.5 years, 55% female) stratified by early childhood adoption status into adoptees (n=5,747) and non-adoptees (n=489,893). We estimated hazard ratios (HRs) per affected nuclear family member, and for polygenic risk scores (PRS) for stroke and MI in Cox models adjusted for baseline age and sex. Results: 12,518 strokes and 23,923 MIs occurred over a 13-year follow-up. In non-adoptees, family history of stroke and heart disease were associated with increased stroke and MI risk, with the strongest association of family history of stroke for incident stroke (HR 1.16 [1.12, 1.19]) and family history of heart disease for incident MI (HR 1.48 [1.45, 1.50]). In adoptees, family history of stroke associated with incident stroke (HR 1.41 [1.06, 1.86]), but family history of heart disease did not associate with incident MI (p>0.5). PRS showed strong disease-specific associations in adoptees and non-adoptees. In non-adoptees, the stroke PRS mediated 6% risk between family history of stroke and incident stroke, and the MI PRS mediated 13% risk between family history of heart disease and MI. Conclusions: Family history of stroke and heart disease increase risk for their respective conditions. Family history of stroke contains a substantial proportion of potentially modifiable non-genetic risk, indicating a need for further research to elucidate these elements for novel prevention strategies, whereas family history of heart disease represents predominantly genetic risk.