Summary of Major Findings: Learn and Serve America, Higher Education

This report provides an overview of results from the first year evaluation of Learn and Serve America, Higher Education (LSAHE), an initiative of the Corporation for National Service (CNS). The evaluation assessed the impacts of LSAHE on communities, students, and institutions in fiscal year 1995

Evaluation of Learn and Serve America, Higher Education: First Year Report, Volume I

This report presents evaluation results for the first year of the Learn and Serve America, Higher Education (LSAHE) initiative, sponsored by the Corporation for National and Community Service (CNS). It addresses impacts of LSAHE on communities, higher education institutions, and service providers

Lipocalin 2 is present in the EAE brain and is modulated by natalizumab

The authors acknowledge the BiogenIdec, for providing Natalizumab (BiogenIdec, Boston, MA, USA). We are thankful to theCOST(European Cooperation in Science and Technology) Action NEURINFNETBM0603. We also thank Dr. Nadine Santos for critically reviewing this manuscript.Multiple sclerosis (MS) is a demyelinating disease that causes major neurological disability in young adults. A definitive diagnosis at the time of the first episode is still lacking, but since early treatment leads to better prognosis, the search for early biomarkers is needed. Here we characterized the transcriptome of the choroid plexus (CP), which is part of the blood-brain barriers (BBBs) and the major site of cerebrospinal fluid production, in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. In addition, cerebrospinal fluid samples from two cohorts of patients with MS and with optic neuritis (ON) were analyzed to confirm the clinical relevance of the findings. Genes encoding for adhesion molecules, chemokines and cytokines displayed the most altered expression, supporting the role of CP as a site of immune-brain interaction in MS. The gene encoding for lipocalin 2 was the most up-regulated; notably, the cerebrospinal fluid lipocalin 2 levels coincided with the active phases of the disease. Immunostaining revealed that neutrophils infiltrating the CP were the source of the increased lipocalin 2 expression in this structure. However, within the brain, lipocalin 2 was also detected in astrocytes, particularly in regions typically affected in patients with MS. The increase of lipocalin 2 in the cerebrospinal fluid and in astrocytes was reverted by natalizumab treatment. Most importantly, the results obtained in the murine model were translatable into humans since patients from two different cohorts presented increased cerebrospinal fluid lipocalin 2 levels. The findings support lipocalin 2 as a valuable molecule for the diagnostic/monitoring panel of MS.This work was supported by a grant from The Dana Foundation (USA) and by a grant from Fundação para a Ciência e Tecnologia(FCT, Portugal) (PIC/IC/83231/2007). Fernanda Marques and Sandro D. Mesquita are recipients of postdoctoral and doctoral fellow- ships from FCT, Portugal, respectively

Myelin dysfunction drives amyloid-β deposition in models of Alzheimer's disease

The incidence of Alzheimer's disease (AD), the leading cause of dementia, increases rapidly with age, but why age constitutes the main risk factor is still poorly understood. Brain ageing affects oligodendrocytes and the structural integrity of myelin sheaths(1), the latter of which is associated with secondary neuroinflammation(2,3). As oligodendrocytes support axonal energy metabolism and neuronal health(4-7), we hypothesized that loss of myelin integrity could be an upstream risk factor for neuronal amyloid-beta (A beta) deposition, the central neuropathological hallmark of AD. Here we identify genetic pathways of myelin dysfunction and demyelinating injuries as potent drivers of amyloid deposition in mouse models of AD. Mechanistically, myelin dysfunction causes the accumulation of the A beta-producing machinery within axonal swellings and increases the cleavage of cortical amyloid precursor protein. Suprisingly, AD mice with dysfunctional myelin lack plaque-corralling microglia despite an overall increase in their numbers. Bulk and single-cell transcriptomics of AD mouse models with myelin defects show that there is a concomitant induction of highly similar but distinct disease-associated microglia signatures specific to myelin damage and amyloid plaques, respectively. Despite successful induction, amyloid disease-associated microglia (DAM) that usually clear amyloid plaques are apparently distracted to nearby myelin damage. Our data suggest a working model whereby age-dependent structural defects of myelin promote A beta plaque formation directly and indirectly and are therefore an upstream AD risk factor. Improving oligodendrocyte health and myelin integrity could be a promising target to delay development and slow progression of AD

Astrocyte layers in the mammalian cerebral cortex revealed by a single-cell in situ transcriptomic map.

Although the cerebral cortex is organized into six excitatory neuronal layers, it is unclear whether glial cells show distinct layering. In the present study, we developed a high-content pipeline, the large-area spatial transcriptomic (LaST) map, which can quantify single-cell gene expression in situ. Screening 46 candidate genes for astrocyte diversity across the mouse cortex, we identified superficial, mid and deep astrocyte identities in gradient layer patterns that were distinct from those of neurons. Astrocyte layer features, established in the early postnatal cortex, mostly persisted in adult mouse and human cortex. Single-cell RNA sequencing and spatial reconstruction analysis further confirmed the presence of astrocyte layers in the adult cortex. Satb2 and Reeler mutations that shifted neuronal post-mitotic development were sufficient to alter glial layering, indicating an instructive role for neuronal cues. Finally, astrocyte layer patterns diverged between mouse cortical regions. These findings indicate that excitatory neurons and astrocytes are organized into distinct lineage-associated laminae.The study was supported by the Paul G. Allen Foundation Distinguished Investigator Program (E.M.U. and D.H.R.), the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation (D.H.R., D.G. and G. C.), BRAIN initiative (1U01 MH105991 to D.G.) and National Institute of Health (1R01 MH109912 to D.G.; P01NS08351 to D.H.R.), National Institute of Health Research and the European Union Seventh Framework (to P.H.), NINDS Informatics Center for Neurogenetics and Neurogenomics (P30 NS062691 to G.C.), Wellcome Trust core support (M.H., O.A.B.), European Research Council (281961 to M.G.H.), Fonds Wetenschappelijk Onderzoek (G066715N and 1523014N to M.G.H.), Stichting Alzheimer Onderzoek (S#16025 to M.G.H.) and VIB Institutional Support and Tech Watch funding (to M.G.H.), Howard Hughes Medical Institute and the Wellcome Trust (to D.H.R.)

Exome-wide association study to identify rare variants influencing COVID-19 outcomes : Results from the Host Genetics Initiative

Publisher Copyright: Copyright: © 2022 Butler-Laporte et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75–10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.Peer reviewe

Common genetic variants in the CLDN2 and PRSS1-PRSS2 loci alter risk for alcohol-related and sporadic pancreatitis

Pancreatitis is a complex, progressively destructive inflammatory disorder. Alcohol was long thought to be the primary causative agent, but genetic contributions have been of interest since the discovery that rare PRSS1, CFTR, and SPINK1 variants were associated with pancreatitis risk. We now report two significant genome-wide associations identified and replicated at PRSS1-PRSS2 (1×10-12) and x-linked CLDN2 (p < 1×10-21) through a two-stage genome-wide study (Stage 1, 676 cases and 4507 controls; Stage 2, 910 cases and 4170 controls). The PRSS1 variant affects susceptibility by altering expression of the primary trypsinogen gene. The CLDN2 risk allele is associated with atypical localization of claudin-2 in pancreatic acinar cells. The homozygous (or hemizygous male) CLDN2 genotype confers the greatest risk, and its alleles interact with alcohol consumption to amplify risk. These results could partially explain the high frequency of alcohol-related pancreatitis in men – male hemizygous frequency is 0.26, female homozygote is 0.07

Identification of common genetic risk variants for autism spectrum disorder

Autism spectrum disorder (ASD) is a highly heritable and heterogeneous group of neurodevelopmental phenotypes diagnosed in more than 1% of children. Common genetic variants contribute substantially to ASD susceptibility, but to date no individual variants have been robustly associated with ASD. With a marked sample-size increase from a unique Danish population resource, we report a genome-wide association meta-analysis of 18,381 individuals with ASD and 27,969 controls that identified five genome-wide-significant loci. Leveraging GWAS results from three phenotypes with significantly overlapping genetic architectures (schizophrenia, major depression, and educational attainment), we identified seven additional loci shared with other traits at equally strict significance levels. Dissecting the polygenic architecture, we found both quantitative and qualitative polygenic heterogeneity across ASD subtypes. These results highlight biological insights, particularly relating to neuronal function and corticogenesis, and establish that GWAS performed at scale will be much more productive in the near term in ASD

Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease

We identified rare coding variants associated with Alzheimer’s disease (AD) in a 3-stage case-control study of 85,133 subjects. In stage 1, 34,174 samples were genotyped using a whole-exome microarray. In stage 2, we tested associated variants (P<1×10-4) in 35,962 independent samples using de novo genotyping and imputed genotypes. In stage 3, an additional 14,997 samples were used to test the most significant stage 2 associations (P<5×10-8) using imputed genotypes. We observed 3 novel genome-wide significant (GWS) AD associated non-synonymous variants; a protective variant in PLCG2 (rs72824905/p.P522R, P=5.38×10-10, OR=0.68, MAFcases=0.0059, MAFcontrols=0.0093), a risk variant in ABI3 (rs616338/p.S209F, P=4.56×10-10, OR=1.43, MAFcases=0.011, MAFcontrols=0.008), and a novel GWS variant in TREM2 (rs143332484/p.R62H, P=1.55×10-14, OR=1.67, MAFcases=0.0143, MAFcontrols=0.0089), a known AD susceptibility gene. These protein-coding changes are in genes highly expressed in microglia and highlight an immune-related protein-protein interaction network enriched for previously identified AD risk genes. These genetic findings provide additional evidence that the microglia-mediated innate immune response contributes directly to AD development