Deciphering Distinct Genetic Risk Factors for FTLD-TDP Pathological Subtypes via Whole-Genome Sequencing.

Frontotemporal lobar degeneration with neuronal inclusions of the TAR DNA-binding protein 43 (FTLD-TDP) is a fatal neurodegenerative disorder with only a limited number of risk loci identified. We report our comprehensive genome-wide association study as part of the International FTLD-TDP Whole-Genome Sequencing Consortium, including 985 cases and 3,153 controls, and meta-analysis with the Dementia-seq cohort, compiled from 26 institutions/brain banks in the United States, Europe and Australia. We confirm UNC13A as the strongest overall FTLD-TDP risk factor and identify TNIP1 as a novel FTLD-TDP risk factor. In subgroup analyses, we further identify for the first time genome-wide significant loci specific to each of the three main FTLD-TDP pathological subtypes (A, B and C), as well as enrichment of risk loci in distinct tissues, brain regions, and neuronal subtypes, suggesting distinct disease aetiologies in each of the subtypes. Rare variant analysis confirmed TBK1 and identified VIPR1 , RBPJL , and L3MBTL1 as novel subtype specific FTLD-TDP risk genes, further highlighting the role of innate and adaptive immunity and notch signalling pathway in FTLD-TDP, with potential diagnostic and novel therapeutic implications.

Expansion of highly interferon-responsive T cells in early-onset Alzheimer's disease.

INTRODUCTION: Altered immune signatures are emerging as a central theme in neurodegenerative disease, yet little is known about immune responses in early-onset Alzheimer's disease (EOAD). METHODS: We examined single-cell RNA-sequencing (scRNA-seq) data from peripheral blood mononuclear cells (PBMCs) and droplet digital polymerase chain reaction (ddPCR) data from CD4 T cells from participants with EOAD and clinically normal controls. RESULTS: We analyzed PBMCs from 16 individuals by scRNA-seq and discovered increased interferon signaling-associated gene (ISAG) expression and striking expansion of antiviral-like ISAGhi T cells in EOAD. Isolating CD4 T cells from 19 individuals, including four cases analyzed by scRNA-seq, we confirmed increased expression of ISAGhi marker genes. Publicly available cerebrospinal fluid leukocyte scRNA-seq data from late-onset mild cognitive impairment and AD also revealed increased expression of interferon-response genes. DISCUSSION: Antiviral-like ISAGhi T cells are expanded in EOAD. Additional research into these cells and the role of heightened peripheral IFN signaling in neurodegeneration is warranted. HIGHLIGHTS: Interferon-responsive T cells expanded in early-onset Alzheimer's disease (AD). Increased interferon-associated gene expression present in early- and late-onset AD. Peripheral immune changes in T and NK cells driven by females with early-onset AD.

Expansion of highly interferon-responsive T cells in early-onset Alzheimer's disease.

INTRODUCTION: Altered immune signatures are emerging as a central theme in neurodegenerative disease, yet little is known about immune responses in early-onset Alzheimer's disease (EOAD). METHODS: We examined single-cell RNA-sequencing (scRNA-seq) data from peripheral blood mononuclear cells (PBMCs) and droplet digital (dd)PCR data from CD4 T cells from participants with EOAD and clinically normal controls. RESULTS: We analyzed ~182,000 PBMCs by scRNA-seq and discovered increased interferon signaling-associated gene (ISAG) expression and striking expansion of antiviral-like ISAGhi T cells in EOAD. We isolated CD4 T cells from additional EOAD cases and confirmed increased expression of ISAGhi marker genes. Publicly available cerebrospinal fluid leukocyte scRNA-seq data from late-onset mild cognitive impairment and AD also revealed increased expression of interferon-response genes. DISCUSSION: ISAGhi T cells, apparently primed for antiviral activity, are expanded in EOAD. Additional research into these cells and the role of heightened peripheral IFN signaling in neurodegeneration is warranted.

Risk factors and abnormal cerebrospinal fluid associate with cognitive symptoms after mild COVID-19.

Cognitive post-acute sequelae of SARS-CoV-2 (PASC) can occur after mild COVID-19. Detailed clinical characterizations may inform pathogenesis. We evaluated 22 adults reporting cognitive PASC and 10 not reporting cognitive symptoms after mild SARS-CoV-2 infection through structured interviews, neuropsychological testing, and optional cerebrospinal fluid (CSF) evaluations (53%). Delayed onset of cognitive PASC occurred in 43% and associated with younger age. Cognitive PASC participants had a higher number of pre-existing cognitive risk factors (2.5 vs. 0; p = 0.03) and higher proportion with abnormal CSF findings (77% vs. 0%; p = 0.01) versus controls. Cognitive risk factors and immunologic mechanisms may contribute to cognitive PASC pathogenesis.