Common coding variant in SERPINA1 increases the risk for large artery stroke.

Large artery atherosclerotic stroke (LAS) shows substantial heritability not explained by previous genome-wide association studies. Here, we explore the role of coding variation in LAS by analyzing variants on the HumanExome BeadChip in a total of 3,127 cases and 9,778 controls from Europe, Australia, and South Asia. We report on a nonsynonymous single-nucleotide variant in serpin family A member 1 (SERPINA1) encoding alpha-1 antitrypsin [AAT; p.V213A; P = 5.99E-9, odds ratio (OR) = 1.22] and confirm histone deacetylase 9 (HDAC9) as a major risk gene for LAS with an association in the 3'-UTR (rs2023938; P = 7.76E-7, OR = 1.28). Using quantitative microscale thermophoresis, we show that M1 (A213) exhibits an almost twofold lower dissociation constant with its primary target human neutrophil elastase (NE) in lipoprotein-containing plasma, but not in lipid-free plasma. Hydrogen/deuterium exchange combined with mass spectrometry further revealed a significant difference in the global flexibility of the two variants. The observed stronger interaction with lipoproteins in plasma and reduced global flexibility of the Val-213 variant most likely improve its local availability and reduce the extent of proteolytic inactivation by other proteases in atherosclerotic plaques. Our results indicate that the interplay between AAT, NE, and lipoprotein particles is modulated by the gate region around position 213 in AAT, far away from the unaltered reactive center loop (357-360). Collectively, our findings point to a functionally relevant balance between lipoproteins, proteases, and AAT in atherosclerosis.

Inflammatory Stroke Extracellular Vesicles Induce Macrophage Activation.

BACKGROUND AND PURPOSE: Extracellular vesicles (EVs) are protein-lipid complexes released from cells, as well as actively exocytosed, as part of normal physiology, but also during pathological processes such as those occurring during a stroke. Our aim was to determine the inflammatory potential of stroke EVs. METHODS: EVs were quantified and analyzed in the sera of patients after an acute stroke (<24 hours; OXVASC [Oxford Vascular Study]). Isolated EV fractions were subjected to untargeted proteomic analysis by liquid chromatography mass-spectrometry/mass-spectrometry and then applied to macrophages in culture to investigate inflammatory gene expression. RESULTS: EV number, but not size, is significantly increased in stroke patients when compared to age-matched controls. Proteomic analysis reveals an overall increase in acute phase proteins, including C-reactive protein. EV fractions applied to monocyte-differentiated macrophage cultures induced inflammatory gene expression. CONCLUSIONS: Together these data show that EVs from stroke patients are proinflammatory in nature and are capable of inducing inflammation in immune cells.

Copeptin and Long-Term Risk of Recurrent Vascular Events After Transient Ischemic Attack and Ischemic Stroke: Population-Based Study.

BACKGROUND AND PURPOSE: Copeptin, the c-terminal portion of provasopressin, is a useful prognostic marker in patients after myocardial infarction and heart failure. More recently, high levels of copeptin have also been associated with worse functional outcome and increased mortality within the first year after ischemic stroke and transient ischemic attack (TIA). However, to date, there are no published data on whether copeptin predicts long-term risk of vascular events after TIA and stroke. METHODS: We measured copeptin levels in consecutive patients with TIA or ischemic stroke in a population-based study (Oxford Vascular Study) recruited from 2002 to 2007 and followed up to 2014. Associations with risk of recurrent vascular events were determined by Cox-regression. RESULTS: During ≈6000 patient-years in 1076 patients, there were 357 recurrent vascular events, including 174 ischemic strokes. After adjustment for age, sex, and risk factors, copeptin was predictive of recurrent vascular events (adjusted hazard ratio per SD, 1.47; 95% confidence interval, 1.31-1.64; P=0.0001), vascular death (1.85; 1.60-2.14; P<0.0001), all-cause death (1.75; 1.58-1.93; P<0.0001), and recurrent ischemic stroke (1.22; 1.04-1.44; P=0.017); and improved model-discrimination significantly: net reclassification improvement for recurrent vascular events (32%; P<0.0001), vascular death (55%; P<0.0001), death (66%; P<0.0001), and recurrent stroke (16%; P=0.044). The predictive value of copeptin was largest in patients with cardioembolic index events (adjusted hazard ratio, 1.84; 95% confidence interval, 1.53-2.20 versus 1.31, 1.14-1.50 in noncardioembolic stroke; P=0.0025). In patients with cardioembolic stroke, high copeptin levels were associated with a 4-fold increased risk of vascular events within the first year of follow-up (adjusted hazard ratio, 4.02; 95% confidence interval, 2.13-7.70). CONCLUSIONS: In patients with TIA and ischemic stroke, copeptin predicted recurrent vascular events and death, particularly after cardioembolic TIA/stroke. Further validation is required, in particular, in studies using more extensive cardiac evaluation.

Biomarkers and mortality after transient ischemic attack and minor ischemic stroke: population-based study.

BACKGROUND AND PURPOSE: Premature death after transient ischemic attack or stroke is more often because of heart disease or cancer than stroke. Previous studies found blood biomarkers not usefully predictive of nonfatal stroke but possibly of all-cause death. This association might be explained by potentially treatable occult cardiac disease or cancer. We therefore aimed to validate the association of a panel of biomarkers with all-cause death, particularly cardiac death and cancer death, despite the absence of associations with risk of nonfatal vascular events. METHODS: Fifteen biomarkers were measured in 929 consecutive patients in a population-based study (Oxford Vascular Study), recruited from 2002 and followed up to 2013. Associations were determined by Cox regression. Model discrimination was assessed by c-statistic and the integrated discrimination improvement. RESULTS: During 5560 patient-years of follow-up, none of the biomarkers predicted risk of nonfatal vascular events. However, soluble tumor necrosis factor α receptor-1, von Willebrand factor, heart-type fatty-acid-binding protein, and N-terminal pro-B-type natriuretic peptide were independently predictive of all-cause death (n=361; adjusted hazard ratio per SD, 95% confidence interval: heart-type fatty-acid-binding protein: 1.31, 1.12-1.56, P=0.002; N-terminal pro-B-type natriuretic peptide: 1.34, 1.11-1.62, P=0.002; soluble tumor necrosis factor α receptor-1: 1.45, 1.26-1.66, P=0.02; von Willebrand factor: 1.19, 1.04-1.36, P=0.01). The independent contribution of the four biomarkers taken together added prognostic information and improved model discrimination (integrated discrimination improvement=0.028, P=0.0001). N-terminal pro-B-type natriuretic peptide was most predictive of vascular death (adjusted hazard ratio=1.80, 95% confidence interval, 1.34-2.41, P<0.0001), whereas heart-type fatty-acid-binding protein predicted cancer deaths (1.64, 1.26-2.12, P=0.0002). Associations were strongest in patients without known prior cardiac disease or cancer. CONCLUSIONS: Several biomarkers predicted death of any cause after transient ischemic attack and minor stroke. N-terminal pro-B-type natriuretic peptide and heart-type fatty-acid-binding protein might improve patient selection for additional screening for occult cardiac disease or cancer, respectively. However, our results require validation in future studies.

Population-based study of blood biomarkers in prediction of subacute recurrent stroke.

BACKGROUND AND PURPOSE: Risk of recurrent stroke is high in the first few weeks after transient ischemic attack or stroke and clinical risk prediction tools have only limited accuracy, particularly after the hyperacute phase. Previous studies of the predictive value of biomarkers have been small, been done in selected populations, and have not concentrated on the acute phase or on intensively treated populations. We aimed to determine the predictive value of a panel of blood biomarkers in intensively treated patients early after transient ischemic attack and stroke. METHODS: We studied 14 blood biomarkers related to inflammation, thrombosis, atherogenesis, and cardiac or neuronal cell damage in early transient ischemic attack or ischemic stroke in a population-based study (Oxford Vascular Study). Biomarker levels were related to 90-day risk of recurrent stroke as hazard ratio (95% confidence interval) per decile increase, adjusted for age and sex. RESULTS: Among 1292 eligible patients, there were 53 recurrent ischemic strokes within 90 days. There were moderate correlations (r=0.40-0.61; P<0.0001) between the inflammatory biomarkers and between the cell damage and thrombotic subsets. Associations with risk of early recurrent stroke were weak, with significant associations limited to interleukin-6 (adjusted hazard ratio, 1.12; 1.01-1.24; P=0.033) and C-reactive protein (adjusted hazard ratio, 1.15; 1.02-1.30; P=0.022) after adjusting for age, sex, hypertension, smoking, and diabetes mellitus although P-selectin seemed to predict stroke after transient ischemic attack (adjusted hazard ratio, 1.28; 1.00-1.63; P=0.046). CONCLUSIONS: In the largest study to date, we found limited predictive use for early recurrent stroke for a panel of inflammatory, thrombotic, and cell damage biomarkers.

Associations of blood biomarkers with glomerular filtration rate in patients with TIA and stroke: population-based study.

BACKGROUND AND PURPOSE: Non-traditional risk factors such as chronic inflammation, oxidative stress and thrombogenic factors are believed to contribute to the excess stroke risk in chronic kidney disease (CKD) by triggering vascular injury and endothelial dysfunction. We aimed to determine how well a panel of biomarkers representative of these factors would correlate with estimated glomerular filtration rate (eGFR) in patients with recent transient ischaemic attack (TIA) or stroke. We also investigated whether eGFR would confound previously reported associations between biomarkers and mortality. METHODS: We studied a panel of 16 blood biomarkers related to inflammation, thrombosis, atherogenesis and cardiac or neuronal cell damage in TIA or ischaemic stroke in a population-based study (Oxford Vascular Study). Biomarker levels were log-transformed and correlated with eGFR, adjusted for age. Cox proportional hazard models were used for survival analysis. RESULTS: Among 1297 patients with TIA or stroke, 52.7% (n=684) of patients had CKD (eGFR <60 mL/min/1.73 m2). There was a moderate correlation between log-eGFR and the log-transformed soluble tumour necrosis factor receptor-1 (R2=0.21), attenuating with adjustment for age (R2=0.12). There were moderate-to-strong correlations with markers of cardiac injury, N-terminal pro-brain natriuretic peptide and heart-type fatty acid binding protein (hFABP, R2=0.14 and 0.34, respectively). The strongest correlation after adjustment for age was between hFABP and eGFR (R2=0.20). Adjusting for eGFR did not impact any biomarker associations with mortality. CONCLUSIONS: Correlations between biomarkers related to inflammation and thrombosis with renal dysfunction in the setting of cerebrovascular events were generally modest after adjustment for age, suggesting that putative risk factors such as chronic inflammation or coagulopathy are unlikely to be important stroke mechanisms in patients with CKD.

Mitochondrial DNA variants modulate N-formylmethionine, proteostasis and risk of late-onset human diseases.

Mitochondrial DNA (mtDNA) variants influence the risk of late-onset human diseases, but the reasons for this are poorly understood. Undertaking a hypothesis-free analysis of 5,689 blood-derived biomarkers with mtDNA variants in 16,220 healthy donors, here we show that variants defining mtDNA haplogroups Uk and H4 modulate the level of circulating N-formylmethionine (fMet), which initiates mitochondrial protein translation. In human cytoplasmic hybrid (cybrid) lines, fMet modulated both mitochondrial and cytosolic proteins on multiple levels, through transcription, post-translational modification and proteolysis by an N-degron pathway, abolishing known differences between mtDNA haplogroups. In a further 11,966 individuals, fMet levels contributed to all-cause mortality and the disease risk of several common cardiovascular disorders. Together, these findings indicate that fMet plays a key role in common age-related disease through pleiotropic effects on cell proteostasis.

Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke.

Genetic factors have been implicated in stroke risk, but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) for ischemic stroke and its subtypes in 3,548 affected individuals and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 affected individuals and 6,281 controls. We replicated previous associations for cardioembolic stroke near PITX2 and ZFHX3 and for large vessel stroke at a 9p21 locus. We identified a new association for large vessel stroke within HDAC9 (encoding histone deacetylase 9) on chromosome 7p21.1 (including further replication in an additional 735 affected individuals and 28,583 controls) (rs11984041; combined P = 1.87 × 10(-11); odds ratio (OR) = 1.42, 95% confidence interval (CI) = 1.28-1.57). All four loci exhibited evidence for heterogeneity of effect across the stroke subtypes, with some and possibly all affecting risk for only one subtype. This suggests distinct genetic architectures for different stroke subtypes.