Bridging the Gap: Multi-Omics Profiling of Brain Tissue in Alzheimer's Disease and Older Controls in Multi-Ethnic Populations.

INTRODUCTION: Multi-omics studies in Alzheimer's disease (AD) revealed many potential disease pathways and therapeutic targets. Despite their promise of precision medicine, these studies lacked African Americans (AA) and Latin Americans (LA), who are disproportionately affected by AD. METHODS: To bridge this gap, Accelerating Medicines Partnership in AD (AMP-AD) expanded brain multi-omics profiling to multi-ethnic donors. RESULTS: We generated multi-omics data and curated and harmonized phenotypic data from AA (n=306), LA (n=326), or AA and LA (n=4) brain donors plus Non-Hispanic White (n=252) and other (n=20) ethnic groups, to establish a foundational dataset enriched for AA and LA participants. This study describes the data available to the research community, including transcriptome from three brain regions, whole genome sequence, and proteome measures. DISCUSSION: Inclusion of traditionally underrepresented groups in multi-omics studies is essential to discover the full spectrum of precision medicine targets that will be pertinent to all populations affected with AD.

Clonal CD8 T Cells Accumulate in the Leptomeninges and Communicate with Microglia in Human Neurodegeneration.

Murine studies have highlighted a crucial role for immune cells in the meninges in surveilling the central nervous system (CNS) and influencing neuroinflammation. However, how meningeal immunity is altered in human neurodegeneration and its effects on CNS inflammation is understudied. We performed the first single-cell analysis of the transcriptomes and T cell receptor (TCR) repertoire of 104,635 immune cells from 55 postmortem human brain and leptomeningeal tissues from donors with neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. RNA and TCR sequencing from paired leptomeninges and brain allowed us to perform lineage tracing to identify the spatial trajectory of clonal T cells in the CNS and its borders. We propose that T cells activated in the brain emigrate to and establish residency in the leptomeninges where they likely contribute to impairments in lymphatic drainage and remotely to CNS inflammation by producing IFNγ and other cytokines. We identified regulatory networks local to the meninges including NK cell-mediated CD8 T cell killing which likely help to control meningeal inflammation. Collectively, these findings provide not only a foundation for future studies into brain border immune surveillance but also highlight important intercellular dynamics that could be leveraged to modulate neuroinflammation.

Clonal CD8 T cells in the leptomeninges are locally controlled and influence microglia in human neurodegeneration.

Recent murine studies have highlighted a crucial role for the meninges in surveilling the central nervous system (CNS) and influencing CNS inflammation. However, how meningeal immunity is altered in human neurodegeneration and its potential effects on neuroinflammation is understudied. In the present study, we performed single-cell analysis of the transcriptomes and T cell receptor repertoire of 72,576 immune cells from 36 postmortem human brain and leptomeninges tissues from donors with neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. We identified the meninges as an important site of antigen presentation and CD8 T cell activation and clonal expansion and found that T cell activation in the meninges is a requirement for infiltration into the CNS. We further found that natural killer cells have the potential to negatively regulate T cell activation locally in the meninges through direct killing and are one of many regulatory mechanisms that work to control excessive neuroinflammation.

Gastrointestinal bleeding in a patient with a continuous-flow biventricular assist device.

The association between continuous-flow left ventricular assist devices (CF-LVADs) and gastrointestinal (GI) bleeding from angiodysplasia is well recognized. However, the association between continuous-flow biventricular assist devices (CF-BIVADs) and bleeding angiodysplasia is less understood. We report a case of GI bleeding from a patient with a CF-BIVAD. The location of GI bleeding was identified by nuclear red blood cell bleeding scan. The vascular malformation leading to the bleed was identified and localized on angiography and then by pathology. The intensity of bleeding, reflected by number of units of packed red blood cells needed for normalization of hemoglobin, as well as the time to onset of bleeding after transplantation, are similar to that seen in the literature for CF-LVADs and pulsatile BIVADs. While angiography only detected a dilated late draining vein, pathology demonstrated the presence of both arterial and venous dilation in the submucosa, vascular abnormalities characteristic of a late arteriovenous malformation.

Damage to Arousal-Promoting Brainstem Neurons with Traumatic Brain Injury.

STUDY OBJECTIVES: Coma and chronic sleepiness are common after traumatic brain injury (TBI). Here, we explored whether injury to arousal-promoting brainstem neurons occurs in patients with fatal TBI. METHODS: Postmortem examination of 8 TBI patients and 10 controls. RESULTS: Compared to controls, TBI patients had 17% fewer serotonergic neurons in the dorsal raphe nucleus (effect size: 1.25), but the number of serotonergic neurons did not differ in the median raphe nucleus. TBI patients also had 29% fewer noradrenergic neurons in the locus coeruleus (effect size: 0.96). The number of cholinergic neurons in the pedunculopontine and laterodorsal tegmental nuclei (PPT/LDT) was similar in TBI patients and controls. CONCLUSIONS: TBI injures arousal-promoting neurons of the mesopontine tegmentum, but this injury is less severe than previously observed in hypothalamic arousal-promoting neurons. Most likely, posttraumatic arousal disturbances are not primarily caused by damage to these brainstem neurons, but arise from an aggregate of injuries, including damage to hypothalamic arousal nuclei and disruption of other arousal-related circuitries.

Disrupted Sleep in Narcolepsy: Exploring the Integrity of Galanin Neurons in the Ventrolateral Preoptic Area.

STUDY OBJECTIVES: To examine the integrity of sleep-promoting neurons of the ventrolateral preoptic nucleus (VLPO) in postmortem brains of narcolepsy type 1 patients. METHODS: Postmortem examination of five narcolepsy and eight control brains. RESULTS: VLPO galanin neuron count did not differ between narcolepsy patients (11,151 ± 3,656) and controls (13,526 ± 9,544). CONCLUSIONS: A normal number of galanin-immunoreactive VLPO neurons in narcolepsy type 1 brains at autopsy suggests that VLPO cell loss is an unlikely explanation for the sleep fragmentation that often accompanies the disease.

Damage to histaminergic tuberomammillary neurons and other hypothalamic neurons with traumatic brain injury.

The need for increased sleep after traumatic brain injury is a common and disabling complaint, yet its etiology is unknown. Previous studies have demonstrated diffuse damage to various hypothalamic systems, but the integrity of the histaminergic tuberomammillary nucleus, a major arousal-promoting system located in the posterior hypothalamus, has never been examined in head trauma patients. Here, we demonstrate that severe head trauma is associated with a marked loss (41%) of histaminergic neurons. Reduced histamine signaling may contribute to increased sleep need, and therapies that enhance histaminergic tone may improve arousal after head trauma or other conditions.

Increase of histaminergic tuberomammillary neurons in narcolepsy.

OBJECTIVE: Narcolepsy is caused by loss of the hypothalamic neurons producing the orexin/hypocretin neuropeptides. One key target of the orexin system is the histaminergic neurons of the tuberomammillary nucleus (TMN), an essential wake-promoting system. As cerebrospinal fluid histamine levels may be low in patients with narcolepsy, we examined histaminergic neurons in patients with narcolepsy and in 2 mouse models of narcolepsy. METHODS: We counted the number of hypothalamic neurons producing orexin, melanin-concentrating hormone, and histamine in 7 narcolepsy patients and 12 control subjects using stereological techniques. We identified histaminergic neurons using immunostaining for histidine decarboxylase. We also examined these systems in 6 wild-type mice, 6 orexin/ataxin-3 transgenic mice, and 5 orexin ligand knockout mice. RESULTS: Compared to controls, narcolepsy patients had 94% more histaminergic TMN neurons (233,572 ± 49,476 vs 120,455 ± 10,665, p < 0.001). This increase was higher in 5 narcolepsy patients with >90% orexin neuron loss than in 2 patients with ≤75% orexin neuron loss (252,279 ± 46,264 vs 186,804 ± 1,256, p = 0.03). Similarly, the number of histaminergic TMN neurons was increased 53% in orexin ligand knockout mice compared to wild-type mice, whereas orexin/ataxin-3 transgenic mice showed an intermediate 28% increase. INTERPRETATION: This surprising increase in histaminergic neurons in narcolepsy may be a compensatory response to loss of excitatory drive from the orexin neurons and may contribute to some of the symptoms of narcolepsy such as preserved consciousness during cataplexy and fragmented nighttime sleep. In addition, this finding may have therapeutic implications, as medications that enhance histamine signaling are now under development.

Diagnostic yield of stereotactic needle-biopsies of sub-cubic centimeter intracranial lesions.

BACKGROUND: Stereotactic brain biopsies are widely used for establishing the diagnosis of intracranial lesions. Here we examine whether stereotactic biopsy of smaller brain lesions, defined for this study as being less than 1 cubic centimeter (1 cc) in volume, are associated with lowered diagnostic yield. METHODS: We conducted a retrospective analysis of 267 consecutive patients who underwent stereotactic brain biopsy between 2007 and 2011. Lesion volumes were calculated and were stratified by <1 or >1 cc. RESULTS: A total of 13 of 246 (5.2%) biopsies for lesions >1 cc resulted in nondiagnostic tissue or an incorrect diagnosis. In contrast, 5 of 21 (23.8%) biopsies for <1 cc lesions yielded nondiagnostic or incorrect diagnosis. Posthoc review of tissue from the <1 cc lesions suggests the neuropathologist's expertise in the handling and analysis of limited specimen as a critical parameter of successful diagnosis. The operative morbidities were low for both the <1 and >1 cc biopsies (0% and 1%, respectively). CONCLUSION: This study demonstrates that stereotactic cerebral biopsy of lesions less than a cubic centimeter in volume results in a lower diagnostic yield versus larger lesions (76.2% versus 94.8%). While auxiliary measures may be taken to improve diagnostic yield, these patients may be best managed in a specialized center with experienced stereotactic neurosurgeons and neuropathologists.

Polyradiculopathies from schwannomatosis.

We describe a case of schwannomatosis presenting as radicular pain and numbness in multiple radicular nerve distributions. There were multiple peripheral nerve tumors detected by magnetic resonance imaging (MRI) at the left vestibular nerve, cauda equina, right radial nerve, thoracic paraspinal nerve, and brachial plexi. Several resected tumors have features of schwannomas, including hypercellular Antoni A areas, hypocellular Antoni B areas, Verocay bodies, and hyalinized blood vessels. The specimens are also positive for immunohistochemical staining for INI1 with diffuse nuclear staining. The findings are consistent with sporadic form of schwannomatosis. This case highlights the importance of using MRI and INI1 immunohistochemistry to differentiate familial schwannomatosis, neurofibromatosis 2 (NF2)-associated schwannomatosis, and sporadic schwannomatosis.

Illusion of stroke: intravascular lymphomatosis.

We describe an unusual case of cerebral intravascular lymphomatosis wherein the patient presented with multiple embolic strokes predominantly in the posterior circulation. Using this case as an illustration, we review the literature of this malignancy, which consists of extranodal diffuse large B-cell lymphoma. For patients with recurrent stroke-like events without cardiac risk factors, the accurate diagnosis requires a high index of suspicion by the neurologist and a brain biopsy specimen demonstrating lymphoma cells within the lumen of cerebral blood vessels. Intravascular lymphomatosis can be treated with systemic chemotherapies, but the response rate and pattern of relapse remain unknown.

Post-transcriptional regulation of O(6)-methylguanine-DNA methyltransferase MGMT in glioblastomas.

BACKGROUND: The DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT) confers therapeutic resistance to DNA alkylating agents, including temozolomide. It is largely believed that MGMT promoter methylation is associated with down regulation of MGMT transcription and corresponding protein expression, thereby predisposing tumor cells to the toxic effect of temozolomide. Here we rigorously examined this underlying assumption. METHODS: We examined the correlation between MGMT promoter methylation, transcription, and protein expression using The Cancer Genome Atlas (TCGA) glioblastoma database as well as an independent collection of glioblastoma specimens. RESULTS: In both analyses, we found that MGMT promoter methylation status correlates well with low MGMT mRNA levels (p = 0.04). On the other hand, glioblastomas with unmethylated MGMT promoters exhibited a wide range of MGMT mRNA expression. Intriguingly, the MGMT mRNA levels correlated poorly with MGMT protein levels by Western blotting (R(2) = 0.04, p = 0.34) or by ImmunoHistoChemical (IHC) stain quantitation (R(2) = 0.02, p = 0.50). To exclude the possibility that the poor correlation was due to substandard specimens, we determined the mRNA and protein levels of Colony Stimulating Factor 1 (CSF1), a gene previously shown to exhibit excellent mRNA/protein correlation. In contrast to MGMT, the mRNA level of CSF1 correlated well with the protein level (R(2) = 0.47, p = 0.001). Importantly, long-term passaged glioblastoma cell lines with comparable MGMT transcript levels differed in MGMT protein levels, suggesting mechanisms of post-transcriptional regulation. Accordingly, the correlation between MGMT promoter methylation and MGMT protein expression was poor (p = 0.27). In silico analysis predicted potential binding sites for several miRNA within the 3'UTR of MGMT, suggesting a mechanism for the post-transcriptional of MGMT. CONCLUSION: Our results suggest mechanisms such as miRNA mediated regulation for post-transcriptional regulation of MGMT. Identification of these mechanisms should enhance the value of MGMT based prognostic or predictive biomarker strategies.

Sources of error in neuropathology intraoperative diagnosis.

OBJECTIVE: The goal of this study was to optimize intraoperative neuropathology consultations by studying trends and sources of diagnostic error. We hypothesized that errors in intraoperative diagnoses would have sampling, technical, and interpretive sources. The study also audited diagnostic strengths, weaknesses and trends associated with increasing experience. We hypothesized that errors would decline and that the accuracy of "qualified" diagnoses would improve with experience. METHODS: The pathologist's first 100 cases (P1), second 100 (P2), and most recent 100 (P3, after ten years in practice) formed the data set. Intraoperative diagnoses were scored as correct, minor error or major error using the final diagnosis as the gold-standard. Incorrect diagnoses were re-examined by two reviewers to identify sources of error. RESULTS: Among the 300 cases there were 22 errors with 11 in P1, 9 in P2 and 2 in P3. Sampling contributed to 17 errors (77%), technical factors to 7 (32%) and interpretive factors to 16 (73%). Improvement in diagnostic accuracy between P1 and P2 (p = 0.8143), or P2 and P3 (p = 0.0582) did not reach significance. However, significant improvement was found between P1 and P3 (p = 0.0184). CONCLUSION: The present study was a practical and informative audit for the pathologist and trainees. It reaffirmed the accuracy of intraoperative neuropathology diagnoses and informed our understanding of sources of error. Most errors were due to a combination of sampling, technical and interpretive factors. A significant improvement in diagnostic proficiency was observed with increasing experience.

A pregnant female with a large intracranial mass: Reviewing the evidence to obtain management guidelines for intracranial meningiomas during pregnancy.

INTRODUCTION: Non-obstetric surgery for intracranial meningioma is uncommon during pregnancy and poses significant risks to both the mother and the fetus. We present a case of a parturient that presented with acute mental status changes and we illustrate the decision making process that resulted in a best-possible outcome. CASE DESCRIPTION: A woman at 29-week gestation presented with acute language and speech deficits and deteriorating mental status after 2 weeks of headache. Imaging demonstrated a large intracranial mass. A multidisciplinary meeting was held to determine the best treatment plan. The decision was to proceed with caesarean delivery under epidural anesthesia to allow intraoperative monitoring of neurological function. Six hours after successful delivery, the patient had acute mental status changes and she was taken to the operating room immediately for resection of her tumor, which turned out to be a clear cell meningioma. DISCUSSION: Cerebral meningioma is usually a slow-growing tumor; however, during pregnancy, the mass may expand rapidly due to hormonal receptor expression. The presentation of this patient would have normally led to urgent resection of the mass. But the complicating factor was her 29-week pregnancy as standard intraoperative treatment during neurosurgery is known to adversely affect the fetus. A multidisciplinary meeting was critical for this patient's care, and is recommended by us when treating such patients.