om as , F e r na n d o G on zález Candelas, SeqCOVID-SPAIN consortium, Tanja Stadler & Richard A. NeherThis is a PDF file of a peer-reviewed paper that has been accepted for publication. Although unedited, the content has been subjected to preliminary formatting. Nature is providing this early version of the typeset paper as a service to our authors and readers. The text and figures will undergo copyediting and a proof review before the paper is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers apply.

Background and Purpose-Abnormal expression of some matrix metalloproteinases (MMP) has shown to play a deleterious role in brain injury in experimental models of cerebral ischemia. We aimed to investigate MMP-2 (gelatinase A) and MMP-9 (gelatinase B) in brain parenchyma in both ischemic and hemorrhagic strokes. Methods-Postmortem fresh brain tissue from 6 ischemic and 8 hemorrhagic stroke patients was obtained within the first 6 hours after death. Finally, 78 brain tissue samples from different areas (infarct, peri-infarct, perihematoma and contralateral hemisphere) were studied. To quantify gelatinase content we performed gelatin zymograms that were confirmed by Western Blot Analysis, immunohistochemistry to localize MMP source, and in situ zymography to detect gelatinase activity. Results-Among ischemic cases, gelatin zymography showed increased MMP-9 content in infarct core although peri-infarct tissue presented also higher levels than contralateral hemisphere (PϽ0.0001 and Pϭ0.042, respectively). Within infarct core, MMP-9 was mainly located around blood vessels, associated to neutrophil infiltration and activated microglial cells. In peri-infarct areas the major source of MMP-9 were microglial cells. Tissue around intracranial hemorrhage also displayed higher MMP-9 levels than contralateral hemisphere (Pϭ0.008) in close relationship with glial cells. MMP-2 was constitutively expressed and remained invariable in different brain areas. Conclusions-Our results demonstrate in situ higher levels of MMP-9 in human brain tissue after ischemic and hemorrhagic stroke, suggesting a contribution of MMP-9 to ischemic brain injury and perihematoma edema. (Stroke.

Background and Purpose-Matrix metalloproteinases (MMPs) are involved in tissue destruction produced by the neuroinflammatory response that follows ischemic stroke. In the present study we use an MMP array to investigate the blood levels of several MMPs in stroke patients and its relation with brain tissue damage and neurological outcome. Methods-Twenty-four patients with middle cerebral artery occlusion who received thrombolytic therapy were included.Blood samples were drawn before tissue plasminogen activator treatment and an MMP array (multiplex enzyme-linked immunosorbent assay [ELISA]) was performed including gelatinases (MMP-2 and MMP-9), collagenases (MMP-1, MMP-8, and MMP-13), stromelysines (MMP-3 and MMP-10), and MMP endogen inhibitors (TIMP-1 and TIMP-2). To assess tissue lesion a serial multimodal MRI study was performed (pretreatment and at 24 hours). Results-Neither initial diffusion lesion nor hypoperfused volume was associated with metalloproteinase expression within the first 3 hours after stroke onset. Nevertheless, a strong correlation was found between MMP-9 and MMP-13 with diffusion-weighted image (DWI) lesion expansion (rϭ0.54, Pϭ0.05 and rϭ0.60, Pϭ0.017, respectively). Baseline levels of both MMP-9 (OR, 14;95% CI, 1.5 to 131; Pϭ0.019) and MMP-13 (OR, 73; 95% CI, 3.9 to 1388; Pϭ0.004) were independent predictors of final increase in brain infarct volume at 24 hours. Conclusions-Our results demonstrate that within the neuroinflammatory response, high levels of MMP-9 and MMP-13 are involved in DWI lesion growth despite thrombolytic therapy, suggesting its ultra-early role in brain injury.

Background The genetic basis of lacunar stroke is poorly understood, with a single locus on 16q24 identified to date. We sought to identify novel associations and provide mechanistic insights into the disease. MethodsWe did a pooled analysis of data from newly recruited patients with an MRI-confirmed diagnosis of lacunar stroke and existing genome-wide association studies (GWAS). Patients were recruited from hospitals in the UK as part of the UK DNA Lacunar Stroke studies 1 and 2 and from collaborators within the International Stroke Genetics Consortium. Cases and controls were stratified by ancestry and two meta-analyses were done: a European ancestry analysis, and a transethnic analysis that included all ancestry groups. We also did a multi-trait analysis of GWAS, in a joint analysis with a study of cerebral white matter hyperintensities (an aetiologically related radiological trait), to find additional genetic associations. We did a transcriptome-wide association study (TWAS) to detect genes for which expression is associated with lacunar stroke; identified significantly enriched pathways using multi-marker analysis of genomic annotation; and evaluated cardiovascular risk factors causally associated with the disease using mendelian randomisation.Findings Our meta-analysis comprised studies from Europe, the USA, and Australia, including 7338 cases and 254 798 con trols, of which 2987 cases (matched with 29 540 controls) were confirmed using MRI. Five loci (ICA1L-WDR12-CARF-NBEAL1, ULK4, SPI1-SLC39A13-PSMC3-RAPSN, ZCCHC14, ZBTB14-EPB41L3) were found to be associa ted with lacunar stroke in the European or transethnic meta-analyses. A further seven loci (SLC25A44-PMF1-BGLAP,