Cortical interneuron-mediated inhibition delays the onset of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a fatal disease resulting from motor neuron degeneration in the cortex and spinal cord. Cortical hyperexcitability is a hallmark feature of amyotrophic lateral sclerosis and is accompanied by decreased intracortical inhibition. Using electrophysiological patch-clamp recordings, we revealed parvalbumin interneurons to be hypoactive in the late pre-symptomatic SOD1*G93A mouse model of amyotrophic lateral sclerosis. We discovered that using adeno-associated virus-mediated delivery of chemogenetic technology targeted to increase the activity of the interneurons within layer 5 of the primary motor cortex, we were able to rescue intracortical inhibition and reduce pyramidal neuron hyperexcitability. Increasing the activity of interneurons in the layer 5 of the primary motor cortex was effective in delaying the onset of amyotrophic lateral sclerosis-associated motor deficits, slowing symptom progression, preserving neuronal populations, and increasing the lifespan of SOD1*G93A mice. Taken together, this study provides novel insights into the pathogenesis and treatment of amyotrophic lateral sclerosis.

Abstract 1: Optical Coherence Tomography Imaging in Acute Ischemic Stroke: Preliminary Animal and Human Results

Background: Studies evaluating endothelial injury after EVT have been done by means of retrieved human thrombus, MR vessel-wall imaging, and animal histopathologic studies. These techniques have limitations, as MR imaging has insufficient spatial resolution to directly visualize endothelium, and histopathologic examinations are ex-vivo and unable to provide real-time patterns of injury.

Objective: Endovascular imaging after EVT using optical coherence tomography (OCT) to examine for vessel injury in real-time.

Methodology: Three swine weighing 35-40kg were selected for the animal model. Autologous venous whole-blood was used to create thrombus. A second-generation stent retriever was used for EVT. Next, three consecutive patients with basilar artery occlusion underwent EVT and endovascular OCT imaging.

Results: In the animal model, revascularization and OCT imaging was successful for all 9 vessels. Endothelial injury was observed in 4/9 (44%) of vessels, and residual thrombus was observed in 4/9 (44%) of vessels despite complete angiographic revascularization. All vessels undergoing EVT after 6 hours had evidence of endothelial injury, and 2/3 (66%) had residual thrombus. Two basilar stroke patients (2/3) 66% had significant residual thrombus despite complete angiographic revascularization. The residual thrombus was also not visible on CT angiography or MR imaging done within 24 hours of EVT.

Conclusions: Endothelial injury and residual thrombus despite complete revascularization is present after EVT and can be observed in real-time using OCT. It is possible that the longer occlusive thrombus is present, the more endothelial injury will occur during EVT.

APOE ε4, white matter hyperintensities, and cognition in Alzheimer and Lewy body dementia

Objective

To determine if APOE ε4 influences the association between white matter hyperintensities (WMH) and cognitive impairment in Alzheimer disease (AD) and dementia with Lewy bodies (DLB).

Methods

A total of 289 patients (AD = 239; DLB = 50) underwent volumetric MRI, neuropsychological testing, and APOE ε4 genotyping. Total WMH volumes were quantified. Neuropsychological test scores were included in a confirmatory factor analysis to identify cognitive domains encompassing attention/executive functions, learning/memory, and language, and factor scores for each domain were calculated per participant. After testing interactions between WMH and APOE ε4 in the full sample, we tested associations of WMH with factor scores using linear regression models in APOE ε4 carriers (n = 167) and noncarriers (n = 122). We hypothesized that greater WMH volume would relate to worse cognition more strongly in APOE ε4 carriers. Findings were replicated in 198 patients with AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI-I), and estimates from both samples were meta-analyzed.

Results

A significant interaction was observed between WMH and APOE ε4 for language, but not for memory or executive functions. Separate analyses in APOE ε4 carriers and noncarriers showed that greater WMH volume was associated with worse attention/executive functions, learning/memory, and language in APOE ε4 carriers only. In ADNI-I, greater WMH burden was associated with worse attention/executive functions and language in APOE ε4 carriers only. No significant associations were observed in noncarriers. Meta-analyses showed that greater WMH volume was associated with worse performance on all cognitive domains in APOE ε4 carriers only.

Conclusion

APOE ε4 may influence the association between WMH and cognitive performance in AD and DLB.

Updates in the management of intradural spinal cord tumors: a radiation oncology focus

Primary spinal cord tumors represent a hetereogeneous group of central nervous system malignancies whose management is complex given the relatively uncommon nature of the disease and variety of tumor subtypes, functional neurologic deficits from the tumor, and potential morbidities associated with definitive treatment. Advances in neuroimaging; integration of diagnostic, prognostic, and predictive molecular testing into tumor classification; and developments in neurosurgical techniques have refined the current role of radiotherapy in the multimodal management of patients with primary spinal cord tumors, and corroborated the need for prospective, multidisciplinary discussion and treatment decision making. Radiotherapeutic technological advances have dramatically improved the entire continuum from treatment planning to treatment delivery, and the development of stereotactic radiosurgery and proton radiotherapy provides new radiotherapy options for patients treated in the definitive, adjuvant, or salvage setting. The objective of this comprehensive review is to provide a contemporary overview of the management of primary intradural spinal cord tumors, with a focus on radiotherapy.

Genome-wide analyses as part of the international FTLD-TDP whole-genome sequencing consortium reveals novel disease risk factors and increases support for immune dysfunction in FTLD

Frontotemporal lobar degeneration with neuronal inclusions of the TAR DNA-binding protein 43 (FTLD-TDP) represents the most common pathological subtype of FTLD. We established the international FTLD-TDP whole-genome sequencing consortium to thoroughly characterize the known genetic causes of FTLD-TDP and identify novel genetic risk factors. Through the study of 1131 unrelated Caucasian patients, we estimated that C9orf72 repeat expansions and GRN loss-of-function mutations account for 25.5% and 13.9% of FTLD-TDP patients, respectively. Mutations in TBK1 (1.5%) and other known FTLD genes (1.4%) were rare, and the disease in 57.7% of FTLD-TDP patients was unexplained by the known FTLD genes. To unravel the contribution of common genetic factors to the FTLD-TDP etiology in these patients, we conducted a two-stage association study comprising the analysis of whole-genome sequencing data from 517 FTLD-TDP patients and 838 controls, followed by targeted genotyping of the most associated genomic loci in 119 additional FTLD-TDP patients and 1653 controls. We identified three genome-wide significant FTLD-TDP risk loci: one new locus at chromosome 7q36 within the DPP6 gene led by rs118113626 (p value = 4.82e - 08, OR = 2.12), and two known loci: UNC13A, led by rs1297319 (p value = 1.27e - 08, OR = 1.50) and HLA-DQA2 led by rs17219281 (p value = 3.22e - 08, OR = 1.98). While HLA represents a locus previously implicated in clinical FTLD and related neurodegenerative disorders, the association signal in our study is independent from previously reported associations. Through inspection of our whole-genome sequence data for genes with an excess of rare loss-of-function variants in FTLD-TDP patients (n ≥ 3) as compared to controls (n = 0), we further discovered a possible role for genes functioning within the TBK1-related immune pathway (e.g., DHX58, TRIM21, IRF7) in the genetic etiology of FTLD-TDP. Together, our study based on the largest cohort of unrelated FTLD-TDP patients assembled to date provides a comprehensive view of the genetic landscape of FTLD-TDP, nominates novel FTLD-TDP risk loci, and strongly implicates the immune pathway in FTLD-TDP pathogenesis.

Prevalence of amyloid-β pathology in distinct variants of primary progressive aphasia

OBJECTIVE

To estimate the prevalence of amyloid positivity, defined by positron emission tomography (PET)/cerebrospinal fluid (CSF) biomarkers and/or neuropathological examination, in primary progressive aphasia (PPA) variants.

METHODS

We conducted a meta-analysis with individual participant data from 1,251 patients diagnosed with PPA (including logopenic [lvPPA, n = 443], nonfluent [nfvPPA, n = 333], semantic [svPPA, n = 401], and mixed/unclassifiable [n = 74] variants of PPA) from 36 centers, with a measure of amyloid-β pathology (CSF [n = 600], PET [n = 366], and/or autopsy [n = 378]) available. The estimated prevalence of amyloid positivity according to PPA variant, age, and apolipoprotein E (ApoE) ε4 status was determined using generalized estimating equation models.

RESULTS

Amyloid-β positivity was more prevalent in lvPPA (86%) than in nfvPPA (20%) or svPPA (16%; p < 0.001). Prevalence of amyloid-β positivity increased with age in nfvPPA (from 10% at age 50 years to 27% at age 80 years, p < 0.01) and svPPA (from 6% at age 50 years to 32% at age 80 years, p < 0.001), but not in lvPPA (p = 0.94). Across PPA variants, ApoE ε4 carriers were more often amyloid-β positive (58.0%) than noncarriers (35.0%, p < 0.001). Autopsy data revealed Alzheimer disease pathology as the most common pathologic diagnosis in lvPPA (76%), frontotemporal lobar degeneration-TDP-43 in svPPA (80%), and frontotemporal lobar degeneration-TDP-43/tau in nfvPPA (64%).

INTERPRETATION

This study shows that the current PPA classification system helps to predict underlying pathology across different cohorts and clinical settings, and suggests that age and ApoE genotype should be considered when interpreting amyloid-β biomarkers in PPA patients. Ann Neurol 2018;84:737-748.

A C6orf10/LOC101929163 locus is associated with age of onset in C9orf72 carriers

The G4C2-repeat expansion in C9orf72 is the most common known cause of amyotrophic lateral sclerosis and frontotemporal dementia. The high phenotypic heterogeneity of C9orf72 patients includes a wide range in age of onset, modifiers of which are largely unknown. Age of onset could be influenced by environmental and genetic factors both of which may trigger DNA methylation changes at CpG sites. We tested the hypothesis that age of onset in C9orf72 patients is associated with some common single nucleotide polymorphisms causing a gain or loss of CpG sites and thus resulting in DNA methylation alterations. Combined analyses of epigenetic and genetic data have the advantage of detecting functional variants with reduced likelihood of false negative results due to excessive correction for multiple testing in genome-wide association studies. First, we estimated the association between age of onset in C9orf72 patients (n = 46) and the DNA methylation levels at all 7603 CpG sites available on the 450 k BeadChip that are mapped to common single nucleotide polymorphisms. This was followed by a genetic association study of the discovery (n = 144) and replication (n = 187) C9orf72 cohorts. We found that age of onset was reproducibly associated with polymorphisms within a 124.7 kb linkage disequilibrium block tagged by top-significant variation, rs9357140, and containing two overlapping genes (LOC101929163 and C6orf10). A meta-analysis of all 331 C9orf72 carriers revealed that every A-allele of rs9357140 reduced hazard by 30% (P = 0.0002); and the median age of onset in AA-carriers was 6 years later than GG-carriers. In addition, we investigated a cohort of C9orf72 negative patients (n = 2634) affected by frontotemporal dementia and/or amyotrophic lateral sclerosis; and also found that the AA-genotype of rs9357140 was associated with a later age of onset (adjusted P = 0.007 for recessive model). Phenotype analyses detected significant association only in the largest subgroup of patients with frontotemporal dementia (n = 2142, adjusted P = 0.01 for recessive model). Gene expression studies of frontal cortex tissues from 25 autopsy cases affected by amyotrophic lateral sclerosis revealed that the G-allele of rs9357140 is associated with increased brain expression of LOC101929163 (a non-coding RNA) and HLA-DRB1 (involved in initiating immune responses), while the A-allele is associated with their reduced expression. Our findings suggest that carriers of the rs9357140 GG-genotype (linked to an earlier age of onset) might be more prone to be in a pro-inflammatory state (e.g. by microglia) than AA-carriers. Further, investigating the functional links within the C6orf10/LOC101929163/HLA-DRB1 pathway will be critical to better define age-dependent pathogenesis of frontotemporal dementia and amyotrophic lateral sclerosis.

A complex of C9ORF72 and p62 uses arginine methylation to eliminate stress granules by autophagy

Mutations in proteins like FUS which cause Amyotrophic Lateral Sclerosis (ALS) result in the aberrant formation of stress granules while ALS-linked mutations in other proteins impede elimination of stress granules. Repeat expansions in C9ORF72, the major cause of ALS, reduce C9ORF72 levels but how this impacts stress granules is uncertain. Here, we demonstrate that C9ORF72 associates with the autophagy receptor p62 and controls elimination of stress granules by autophagy. This requires p62 to associate via the Tudor protein SMN with proteins, including FUS, that are symmetrically methylated on arginines. Mice lacking p62 accumulate arginine-methylated proteins and alterations in FUS-dependent splicing. Patients with C9ORF72 repeat expansions accumulate symmetric arginine dimethylated proteins which co-localize with p62. This suggests that C9ORF72 initiates a cascade of ALS-linked proteins (C9ORF72, p62, SMN, FUS) to recognize stress granules for degradation by autophagy and hallmarks of a defect in this process are observable in ALS patients.

Many Amyotrophic Lateral Sclerosis (ALS)-linked mutations cause accumulation of stress granules, and most ALS cases are caused by repeat expansions in C9ORF72. Here the authors show that C9ORF72 and the autophagy receptor p62 interact to associate with proteins symmetrically dimethylated on arginines such as FUS, to eliminate stress granules by autophagy.

APOE-ε4 associates with hippocampal volume, learning, and memory across the spectrum of Alzheimer's disease and dementia with Lewy bodies

INTRODUCTION

Although the apolipoprotein E ε4-allele (APOE-ε4) is a susceptibility factor for Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), its relationship with imaging and cognitive measures across the AD/DLB spectrum remains unexplored.

METHODS

We studied 298 patients (AD = 250, DLB = 48; 38 autopsy-confirmed; NCT01800214) using neuropsychological testing, volumetric magnetic resonance imaging, and APOE genotyping to investigate the association of APOE-ε4 with hippocampal volume and learning/memory phenotypes, irrespective of diagnosis.

RESULTS

Across the AD/DLB spectrum: (1) hippocampal volumes were smaller with increasing APOE-ε4 dosage (no genotype × diagnosis interaction observed), (2) learning performance as assessed by total recall scores was associated with hippocampal volumes only among APOE-ε4 carriers, and (3) APOE-ε4 carriers performed worse on long-delay free word recall.

DISCUSSION

These findings provide evidence that APOE-ε4 is linked to hippocampal atrophy and learning/memory phenotypes across the AD/DLB spectrum, which could be useful as biomarkers of disease progression in therapeutic trials of mixed disease.

Dysregulation of chromatin remodelling complexes in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease with paralysis resulting from dysfunction and loss of motor neurons. A common neuropathological finding is attrition of motor neuron dendrites, which make central connections vital to motor control. The chromatin remodelling complex, neuronal Brahma-related gene 1 (Brg1)-associated factor complex (nBAF), is critical for neuronal differentiation, dendritic extension and synaptic function. We have identified loss of the crucial nBAF subunits Brg1, Brg1-associated factor 53b and calcium responsive transactivator in cultured motor neurons expressing FUS or TAR-DNA Binding Protein 43 (TDP-43) mutants linked to familial ALS. When plasmids encoding wild-type or mutant human FUS or TDP-43 were expressed in motor neurons of dissociated spinal cord cultures prepared from E13 mice, mutant proteins in particular accumulated in the cytoplasm. Immunolabelling of nBAF subunits was reduced in proportion to loss of nuclear FUS or TDP-43 and depletion of Brg1 was associated with nuclear retention of Brg1 mRNA. Dendritic attrition (loss of intermediate and terminal dendritic branches) occurred in motor neurons expressing mutant, but not wild-type, FUS or TDP-43. This attrition was delayed by ectopic over-expression of Brg1 and was reproduced by inhibiting Brg1 activity either through genetic manipulation or treatment with the chemical inhibitor, (E)-1-(2-Hydroxyphenyl)-3-((1R, 4R)-5-(pyridin-2-yl)-2, 5-diazabicyclo[2.2.1]heptan-2-yl)prop-2-en-1-one, demonstrating the importance of Brg1 to maintenance of dendritic architecture. Loss of nBAF subunits was also documented in spinal motor neurons in autopsy tissue from familial amyotrophic sclerosis (chromosome 9 open reading frame 72 with G4C2 nucleotide expansion) and from sporadic cases with no identified mutation, pointing to dysfunction of nBAF chromatin remodelling in multiple forms of ALS.

The effect of white matter hyperintensities on verbal memory: Mediation by temporal lobe atrophy

OBJECTIVE

To determine the relationship between white matter hyperintensities (WMH) presumed to indicate disease of the cerebral small vessels, temporal lobe atrophy, and verbal memory deficits in Alzheimer disease (AD) and other dementias.

METHODS

We recruited groups of participants with and without AD, including strata with extensive WMH and minimal WMH, into a cross-sectional proof-of-principle study (n = 118). A consecutive case series from a memory clinic was used as an independent validation sample (n = 702; Sunnybrook Dementia Study; NCT01800214). We assessed WMH volume and left temporal lobe atrophy (measured as the brain parenchymal fraction) using structural MRI and verbal memory using the California Verbal Learning Test. Using path modeling with an inferential bootstrapping procedure, we tested an indirect effect of WMH on verbal recall that depends sequentially on temporal lobe atrophy and verbal learning.

RESULTS

In both samples, WMH predicted poorer verbal recall, specifically due to temporal lobe atrophy and poorer verbal learning (proof-of-principle -1.53, 95% bootstrap confidence interval [CI] -2.45 to -0.88; and confirmation -0.66, 95% CI [-0.95 to -0.41] words). This pathway was significant in subgroups with (-0.20, 95% CI [-0.38 to -0.07] words, n = 363) and without (-0.71, 95% CI [-1.12 to -0.37] words, n = 339) AD. Via the identical pathway, WMH contributed to deficits in recognition memory (-1.82%, 95% CI [-2.64% to -1.11%]), a sensitive and specific sign of AD.

CONCLUSIONS

Across dementia syndromes, WMH contribute indirectly to verbal memory deficits considered pathognomonic of Alzheimer disease, specifically by contributing to temporal lobe atrophy.

Unaffected mosaic C9orf72 case: RNA foci, dipeptide proteins, but upregulated C9orf72 expression

Objective

Suggested C9orf72 disease mechanisms for amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration include C9orf72 haploinsufficiency, G₄C₂/C₄G₂ RNA foci, and dipeptide repeat (DPR) proteins translated from the G₄C₂ expansion; however, the role of small expansions (e.g., 30–90 repeats) is unknown and was investigated here.

Methods

We conducted a molecular and pathology study of a family in which the father (unaffected at age 90) carried a 70-repeat allele in blood DNA that expanded to ≈1,750 repeats in his children, causing ALS.

Results

Southern blotting revealed different degrees of mosaicism of small and large expansions in the father's tissues from the CNS. Surprisingly, in each mosaic tissue, C9orf72 mRNA levels were significantly increased compared to an ALS-affected daughter with a large expansion. Increased expression correlated with higher levels of the 70-repeat allele (the upregulation was also evident at the protein level). Remarkably, RNA foci and DPR burdens were similar or even significantly increased (in cerebellum) in the unaffected father compared to the daughter with ALS. However, the father did not display TDP-43 pathology and signs of neurodegeneration.

Conclusion

The presence of RNA foci and DPR pathology was insufficient for disease manifestation and TDP-43 pathology in the mosaic C9orf72 carrier with upregulated C9orf72 expression. It is important to conduct an investigation of similar cases, which could be found among unaffected parents of sporadic C9orf72 patients (e.g., 21% among Finnish patients with ALS). Caution should be taken when consulting carriers of small expansions because disease manifestation could be dependent on the extent of the somatic instability in disease-relevant tissues.

Clinical and neuropathological features of ALS/FTD with TIA1 mutations

Mutations in the stress granule protein T-cell restricted intracellular antigen 1 (TIA1) were recently shown to cause amyotrophic lateral sclerosis (ALS) with or without frontotemporal dementia (FTD). Here, we provide detailed clinical and neuropathological descriptions of nine cases with TIA1 mutations, together with comparisons to sporadic ALS (sALS) and ALS due to repeat expansions in C9orf72 (C9orf72+). All nine patients with confirmed mutations in TIA1 were female. The clinical phenotype was heterogeneous with a range in the age at onset from late twenties to the eighth decade (mean = 60 years) and disease duration from one to 6 years (mean = 3 years). Initial presentation was either focal weakness or language impairment. All affected individuals received a final diagnosis of ALS with or without FTD. No psychosis or parkinsonism was described. Neuropathological examination on five patients found typical features of ALS and frontotemporal lobar degeneration (FTLD-TDP, type B) with anatomically widespread TDP-43 proteinopathy. In contrast to C9orf72+ cases, caudate atrophy and hippocampal sclerosis were not prominent. Detailed evaluation of the pyramidal motor system found a similar degree of neurodegeneration and TDP-43 pathology as in sALS and C9orf72+ cases; however, cases with TIA1 mutations had increased numbers of lower motor neurons containing round eosinophilic and Lewy body-like inclusions on HE stain and round compact cytoplasmic inclusions with TDP-43 immunohistochemistry. Immunohistochemistry and immunofluorescence failed to demonstrate any labeling of inclusions with antibodies against TIA1. In summary, our TIA1 mutation carriers developed ALS with or without FTD, with a wide range in age at onset, but without other neurological or psychiatric features. The neuropathology was characterized by widespread TDP-43 pathology, but a more restricted pattern of neurodegeneration than C9orf72+ cases. Increased numbers of round eosinophilic and Lewy-body like inclusions in lower motor neurons may be a distinctive feature of ALS caused by TIA1 mutations.

TIA1 Mutations in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Promote Phase Separation and Alter Stress Granule Dynamics

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are age-related neurodegenerative disorders with shared genetic etiologies and overlapping clinical and pathological features. Here we studied a novel ALS/FTD family and identified the P362L mutation in the low-complexity domain (LCD) of T cell-restricted intracellular antigen-1 (TIA1). Subsequent genetic association analyses showed an increased burden of TIA1 LCD mutations in ALS patients compared to controls (p = 8.7 × 10^-6). Postmortem neuropathology of five TIA1 mutations carriers showed a consistent pathological signature with numerous round, hyaline, TAR DNA-binding protein 43 (TDP-43)-positive inclusions. TIA1 mutations significantly increased the propensity of TIA1 protein to undergo phase transition. In live cells, TIA1 mutations delayed stress granule (SG) disassembly and promoted the accumulation of non-dynamic SGs that harbored TDP-43. Moreover, TDP-43 in SGs became less mobile and insoluble. The identification of TIA1 mutations in ALS/FTD reinforces the importance of RNA metabolism and SG dynamics in ALS/FTD pathogenesis.

DNA methylation age-acceleration is associated with disease duration and age at onset in C9orf72 patients

The repeat expansion in C9orf72 is the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia. C9orf72 patients present with a wide range in disease duration and age of onset. The strongest risk factor for both syndromes is aging, which was linked to DNA methylation (DNAm) age based on the cumulative assessment of the methylation levels of 353 CpGs included on the genome-wide 450k BeadChip. DNAm age may reflect biological age better than chronological age. We conducted a genome-wide blood DNA methylation study of 46 unrelated C9orf72 patients. After correction for multiple testing, none of the CpGs demonstrated association between its methylation level and disease duration or age of onset. However, we detected a significant reverse correlation of DNAm age-acceleration with disease duration and age of onset, suggesting that for every 5-year increase in DNAm age-acceleration there is a 3.2-year earlier age of onset and 1.5-year shorter disease duration. The significant correlations remain after adjusting for gender, TMEM106B genotypes, disease phenotype and C9orf72 5′CpG island methylation status. A similar trend was observed for the blood DNA of affected members of an extended C9orf72 family; and tissues from the central nervous system of C9orf72 autopsy cases. For instance, regression analysis suggested that a 5-year increase in DNAm age-acceleration is linked to an earlier age of onset by 4.7 or 5.5 years for frontal cortex or spinal cord, respectively. Blood DNAm age may be a useful biomarker for biological age, because blood DNAm age-acceleration was similar to all investigated brain tissues, except for cerebellum that ages more slowly. In conclusion, DNA methylation analysis of C9orf72 patients revealed that increased DNAm age-acceleration is associated with a more severe disease phenotype with a shorter disease duration and earlier age of onset.

Collagenosis of the Deep Medullary Veins: An Underrecognized Pathologic Correlate of White Matter Hyperintensities and Periventricular Infarction?

White matter hyperintensities (WMH) are prevalent. Although arteriolar disease has been implicated in their pathogenesis, venous pathology warrants consideration. We investigated relationships of WMH with histologic venous, arteriolar and white matter abnormalities and correlated findings with premortem neuroimaging. Three regions of periventricular white matter were sampled from archived autopsy brains of 24 pathologically confirmed Alzheimer disease (AD) and 18 age-matched nonAD patients. Using trichrome staining, venous collagenosis (VC) of periventricular veins (<150 µm in diameter) was scored for severity of wall thickening and occlusion; percent stenosis by collagenosis of large caliber (>200 µm) veins (laVS) was measured. Correlations were made between WMH in premortem neuroimaging and vascular and white matter pathology. We found greater VC (U(114) = 2092.5, p = 0.005 and U(114) = 2121.5, p = 0.002 for small and medium caliber veins, respectively) and greater laVS (t(110) = 3.46, p = 0.001) in patients with higher WMH scores; WMH scores correlated with VC (rs(114) = 0.27, p = 0.004) and laVS (rs(110) = 0.38, p < 0.001). By multiple linear regression analysis, the strongest predictor of WMH score was laVS (β = 0.338, p < 0.0001). VC was frequent in patients with periventricular infarcts identified on imaging. We conclude that periventricular VC is associated with WMH in both AD and nonAD patients and the potential roles of VC in WMH pathogenesis merit further study.

Intravascular large B-cell lymphoma presenting as Richter's syndrome with cerebral involvement in a patient with chronic lymphocytic leukemia

Intravascular large B-cell lymphoma (IVLBCL) is an aggressive non-Hodgkin's lymphoma which can present with B symptoms, rash, and neurological deterioration. Up to 10% of cases of IVLBCL are associated with other hematological neoplasms, including this extremely rare presentation of IVLBCL as Richter's transformation in chronic lymphocytic leukemia.

BACH2 immunodeficiency illustrates an association between super-enhancers and haploinsufficiency

The transcriptional programs that guide lymphocyte differentiation depend on the precise expression and timing of transcription factors (TFs). The TF BACH2 is essential for T and B lymphocytes and is associated with an archetypal super-enhancer (SE). Single-nucleotide variants in the BACH2 locus are associated with several autoimmune diseases, but BACH2 mutations that cause Mendelian monogenic primary immunodeficiency have not previously been identified. Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency and intestinal inflammation. The mutations disrupted protein stability by interfering with homodimerization or by causing aggregation. We observed analogous lymphocyte defects in Bach2-heterozygous mice. More generally, we observed that genes that cause monogenic haploinsufficient diseases were substantially enriched for TFs and SE architecture. These findings reveal a previously unrecognized feature of SE architecture in Mendelian diseases of immunity: heterozygous mutations in SE-regulated genes identified by whole-exome/genome sequencing may have greater significance than previously recognized.

CADASIL accelerated by acute hypotension: Arterial and venous contribution to leukoaraiosis

OBJECTIVE

To underline the importance of blood pressure regulation in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and to describe changes that occur in the veins in this condition, specifically venous collagenosis associated with leukoaraiosis.

METHODS

Case report with neuroimaging and pathologic data.

RESULTS

A 61-year-old man with genetically confirmed CADASIL was initially lucid following a motor vehicle accident but subsequently became hypotensive (60/40 mm Hg) due to an open femur fracture and required intubation. Multiple new white matter infarcts appeared on brain imaging. A second hypotensive episode days later was associated with new coin-sized infarcts in the bilateral corona radiata and cerebellar peduncles, and resulted in quadriplegia. No embolic source was found on cardiac or vascular imaging. He died 5 weeks post trauma. Autopsy revealed extensive subcortical and periventricular leukoencephalopathy and multiple cavitations involving deep subcortical gray and white matter. Small arteries had thickened walls, disruption of the muscularis, and intimal periodic acid-Schiff (PAS)-positive material. Both larger periventricular and small caliber veins had thickened walls that were PAS-negative and trichrome-positive, consistent with venous collagenosis. There was no pathologic evidence of global hypoxia or diffuse axonal injury.

CONCLUSIONS

The findings suggest rapid acceleration of CADASIL pathology from acute hypotension in the setting of impaired vasoreactivity. In addition, collagenosis of veins in the affected white matter regions suggests that the veins may play an important, though largely overlooked, role in maintaining white matter integrity.