Schwann Cell Remyelination in the Multiple Sclerosis Central Nervous System

Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating disease. Failure to remyelinate successfully is common in MS lesions, often with consequent neuronal/axonal damage. CNS myelin is normally produced by oligodendroglial cells. Remyelination by Schwann cells (SchC) has been reported in spinal cord demyelination, in which SchCs are in close proximity to CNS myelin. We identified an MS cerebral lesion that was remyelinated by SchCs. This prompted us to query the extent of SchC remyelination in the brain and spinal cords of additional autopsied MS specimens. CNS tissues were obtained from the autopsies of 14 MS cases. Remyelinated lesions were identified by Luxol fast blue-periodic-acid Schiff and solochrome cyanine staining. Deparaffinized sections containing remyelinated lesions were stained with anti-glial fibrillary acid protein to identify reactive astrocytes. Glycoprotein P zero (P0) is a protein exclusive to peripheral but not CNS myelin. Areas of SchC remyelination were identified by staining with anti-P0. Myelinated regions in the index case cerebral lesion were confirmed to be of SchC origin using anti-P0 staining. Subsequently, 64 MS lesions from 14 autopsied MS cases were examined, and 23 lesions in 6 cases showed remyelination by SchCs. Lesions from the cerebrum, brainstem, and spinal cord were examined in each case. When present, SchC remyelination was most commonly located adjacent to the venules and associated with a lower surrounding density of glial fibrillary acid protein+ reactive astrocytes than areas of only oligodendroglial cell remyelination. The difference was significant only for spinal cord and brainstem lesions but not for lesions located in the brain. In conclusion, we demonstrated SchC remyelination in the cerebrum, brainstem, and spinal cord of 6 autopsied MS cases. To our knowledge, this is the first report of supratentorial SchC remyelination in MS.

Sleep deprivation exacerbates microglial reactivity and Aβ deposition in a TREM2-dependent manner in mice

Sleep loss is associated with cognitive decline in the aging population and is a risk factor for Alzheimer's disease (AD). Considering the crucial role of immunomodulating genes such as that encoding the triggering receptor expressed on myeloid cells type 2 (TREM2) in removing pathogenic amyloid-β (Aβ) plaques and regulating neurodegeneration in the brain, our aim was to investigate whether and how sleep loss influences microglial function in mice. We chronically sleep-deprived wild-type mice and the 5xFAD mouse model of cerebral amyloidosis, expressing either the humanized TREM2 common variant, the loss-of-function R47H AD-associated risk variant, or without TREM2 expression. Sleep deprivation not only enhanced TREM2-dependent Aβ plaque deposition compared with 5xFAD mice with normal sleeping patterns but also induced microglial reactivity that was independent of the presence of parenchymal Aβ plaques. We investigated lysosomal morphology using transmission electron microscopy and found abnormalities particularly in mice without Aβ plaques and also observed lysosomal maturation impairments in a TREM2-dependent manner in both microglia and neurons, suggesting that changes in sleep modified neuro-immune cross-talk. Unbiased transcriptome and proteome profiling provided mechanistic insights into functional pathways triggered by sleep deprivation that were unique to TREM2 and Aβ pathology and that converged on metabolic dyshomeostasis. Our findings highlight that sleep deprivation directly affects microglial reactivity, for which TREM2 is required, by altering the metabolic ability to cope with the energy demands of prolonged wakefulness, leading to further Aβ deposition, and underlines the importance of sleep modulation as a promising future therapeutic approach.

Schwann Cells and Myelin in Human Peripheral Nerve: Major Protein Components Vary with Age, Axon Size and Pathology

AIMS

We examined major protein components of Schwann cells (SC) and myelin in normal and diseased human peripheral nerves.

METHODS

We evaluated distributions of neural cell adhesion molecule (NCAM), P0 protein (P0), and myelin basic protein (MBP) in frozen sections of 98 sural nerves.

RESULTS

Non-myelinating SC in normal adults, contained NCAM, but not P0 or MBP. With chronic axon loss, SC without associated axons (Büngner band cells) often co-stained for both NCAM and P0. Onion bulb cells also co-stained for both P0 and NCAM. Infants had many SC with MBP but no P0. All myelin sheaths contained P0. Myelin around large, and some intermediate-sized, axons co-stained for both MBP and P0. Myelin on other intermediate-sized axons had P0, but no MBP. Regenerated axons often had sheaths with MBP, P0, and some NCAM. During active axon degeneration, myelin ovoids often co-stained for MBP, P0 and NCAM. Demyelinating neuropathy patterns included SC (NCAM) loss, and myelin with abnormally distributed, or reduced, P0.

CONCLUSIONS

Peripheral nerve SC and myelin have varied molecular phenotypes, related to age, axon size and nerve pathology. In normal adult peripheral nerve, myelin has two different patterns of molecular composition. MBP is mostly absent from myelin around a population of intermediate-sized axons, while P0 is present in myelin around all axons. Denervated SC have a molecular signature that differs from normal SC types. With acute denervation, SC may stain for both NCAM and MBP. Chronically denervated SC often stain for both NCAM and P0.

Xanthogranulomatous epithelial tumors and keratin-positive giant cell-rich soft tissue tumors: two aspects of a single entity with frequent HMGA2-NCOR2 fusions

Xanthogranulomatous epithelial tumor (XGET) and keratin-positive giant cell-rich soft tissue tumor with HMGA2-NCOR2 fusion (KPGCT) are two recently described neoplasms with both distinct and overlapping clinical and histopathologic features. We hypothesized that XGET and KPGCT may be related and represent a histologic spectrum of a single entity. To test this, we sought to characterize the clinical, radiographic, immunohistochemical, ultrastructural and molecular features of additional tumors with features of XGET and/or KPGCT, which we refer to descriptively as keratin-positive xanthogranulomatous/giant cell-rich tumors (KPXG/GCT). The archives were searched for potential cases of KPXG/GCT. Clinical and imaging features were noted. Slides were assessed for histologic and immunohistochemical findings. Ultrastructural and next generation RNA sequencing-based analysis were also performed. Nine cases were identified arising in seven women and two men [median age of 33 years (range: 12-87)]. Median tumor size was 4 cm (range: 2.4-14.0 cm) and tumors presented in the thigh (2), buttock (1), forearm (2), groin (1), cranial fossa (1), ilium (1), and tibia (1). Morphologically, tumors were most frequently characterized by a fibrous capsule, with associated lymphoid reaction, enclosing a polymorphous proliferation of histiocytes, giant cells (Touton and osteoclast-types), mixed inflammatory infiltrate, hemorrhage and hemosiderin deposition, which imparted a variably xanthogranulomatous to giant cell tumor-like appearance. One case clearly showed mononuclear cells with eosinophilic cytoplasm characteristic of XGET. All cases expressed keratin and 7 of 9 were found to harbor HMGA2-NCOR2 fusions including cases with xanthogranulomatous appearance. One patient developed local recurrence and multifocal pulmonary lesions, which were radiographically suspicious for metastases. Shared clinical, histologic and immunohistochemical features, and the shared presence of HMGA2-NCOR2 fusions supports interpretation of KPXG/GCT as a single entity which includes XGET and KPGCT. Given limited clinical follow-up to date and rare cases with apparently aggressive findings, we provisionally regard these tumors as having uncertain biologic potential.

Macrophage depletion blocks congenital SARM1-dependent neuropathy

Axon loss contributes to many common neurodegenerative disorders. In healthy axons, the axon survival factor NMNAT2 inhibits SARM1, the central executioner of programmed axon degeneration. We identified 2 rare NMNAT2 missense variants in 2 brothers afflicted with a progressive neuropathy syndrome. The polymorphisms resulted in amino acid substitutions V98M and R232Q, which reduced NMNAT2 NAD+-synthetase activity. We generated a mouse model to mirror the human syndrome and found that Nmnat2V98M/R232Q compound-heterozygous CRISPR mice survived to adulthood but developed progressive motor dysfunction, peripheral axon loss, and macrophage infiltration. These disease phenotypes were all SARM1-dependent. Remarkably, macrophage depletion therapy blocked and reversed neuropathic phenotypes in Nmnat2V98M/R232Q mice, identifying a SARM1-dependent neuroimmune mechanism as a key driver of disease pathogenesis. These findings demonstrate that SARM1 induced inflammatory neuropathy and highlight the potential of immune therapy as a treatment for this rare syndrome and other neurodegenerative conditions associated with NMNAT2 loss and SARM1 activation.

Evaluating brain damage in multiple sclerosis with simultaneous multi-angular-relaxometry of tissue

OBJECTIVE

Multiple sclerosis (MS) is a common demyelinating central nervous system disease. MRI methods that can quantify myelin loss are needed for trials of putative remyelinating agents. Quantitative magnetization transfer MRI introduced the macromolecule proton fraction (MPF), which correlates with myelin concentration. We developed an alternative approach, Simultaneous-Multi-Angular-Relaxometry-of-Tissue (SMART) MRI, to generate MPF. Our objective was to test SMART-derived MPF metric as a potential imaging biomarker of demyelination.

METHODS

Twenty healthy control (HC), 11 relapsing-remitting MS (RRMS), 22 progressive MS (PMS), and one subject with a biopsied tumefactive demyelinating lesion were scanned at 3T using SMART MRI. SMART-derived MPF metric was determined in normal-appearing cortical gray matter (NAGM), normal-appearing subcortical white matter (NAWM), and demyelinating lesions. MPF metric was evaluated for correlations with physical and cognitive test scores. Comparisons were made between HC and MS and between MS subtypes. Furthermore, correlations were determined between MPF and neuropathology in the biopsied person.

RESULTS

SMART-derived MPF in NAGM and NAWM were lower in MS than HC (p < 0.001). MPF in NAGM, NAWM and lesions differentiated RRMS from PMS (p < 0.01, p < 0.001, p < 0.001, respectively), whereas lesion volumes did not. MPF in NAGM, NAWM and lesions correlated with the Expanded Disability Status Scale (p < 0.01, p < 0.001, p < 0.001, respectively) and nine-hole peg test (p < 0.001, p < 0.001, p < 0.01, respectively). MPF was lower in the histopathologically confirmed inflammatory demyelinating lesion than the contralateral NAWM and increased in the biopsied lesion over time, mirroring improved clinical performance.

INTERPRETATION

SMART-derived MPF metric holds potential as a quantitative imaging biomarker of demyelination and remyelination.

Loss of Stathmin-2, a hallmark of TDP-43-associated ALS, causes motor neuropathy

TDP-43 mediates proper Stathmin-2 (STMN2) mRNA splicing, and STMN2 protein is reduced in the spinal cord of most patients with amyotrophic lateral sclerosis (ALS). To test the hypothesis that STMN2 loss contributes to ALS pathogenesis, we generated constitutive and conditional STMN2 knockout mice. Constitutive STMN2 loss results in early-onset sensory and motor neuropathy featuring impaired motor behavior and dramatic distal neuromuscular junction (NMJ) denervation of fast-fatigable motor units, which are selectively vulnerable in ALS, without axon or motoneuron degeneration. Selective excision of STMN2 in motoneurons leads to similar NMJ pathology. STMN2 knockout heterozygous mice, which better model the partial loss of STMN2 protein found in patients with ALS, display a slowly progressive, motor-selective neuropathy with functional deficits and NMJ denervation. Thus, our findings strongly support the hypothesis that STMN2 reduction owing to TDP-43 pathology contributes to ALS pathogenesis.

Osteology-focused redescription and description of the blood-feeding candirus Paracanthopoma parva and Paravandellia alleynei sp.n. (Trichomycteridae: Vandelliinae)

This study resolves a significant impediment to the taxonomy of the Neotropical endemic hematophagous candirus by providing the first high-resolution, CT-based osteological descriptions of type and nontype specimens of Paracanthopoma parva, type species of the genus. We also describe the distinctive new species Paravandellia alleynei based on specimens that were previously misidentified as Parac. parva in the only taxonomic study of that species since its 1935 description. Paracanthopoma parva is distinguished from all nominal congeners by its parietosupraoccipital and caudal skeleton morphology and by various meristics, including numbers of teeth on median premaxilla, vertebrae, and procurrent and principal caudal-fin rays. Paravandellia alleynei differs from both nominal congeners (Paravandellia oxyptera and Paravandellia phaneronema) by the unique morphology of its maxilla, mesethmoid and opercular apparatus, relative position of the pelvic- and anal-fin origins, orientation of the opercular odontodes, and various meristics, including numbers of vertebrae, median premaxillary teeth, medial teeth on premaxilla, branchiostegal rays, opercular and interopercular odontodes, distal claw-like premaxillary teeth, dorsal-fin rays and dentary teeth. This is the first species of Paravandellia recognized from Guyana and the Essequibo River basin. It is currently known only from two type specimens from the lower Essequibo River basin and 43 nontype specimens from the upper Branco River basin. By providing the first skeletal observations for type specimens of the type species Parac. parva and for topotypic specimens of all three nominal species of Paravandellia, we clarify and confirm the diagnosis of Parac. parva and establish a robust foundation for ongoing taxonomic revisions of these two small-sized and species-poor, yet trans-continentally distributed genera, both of which contain considerable unrecognized diversity.

Overexpressing low-density lipoprotein receptor reduces tau-associated neurodegeneration in relation to apoE-linked mechanisms

APOE is the strongest genetic risk factor for late-onset Alzheimer's disease. ApoE exacerbates tau-associated neurodegeneration by driving microglial activation. However, how apoE regulates microglial activation and whether targeting apoE is therapeutically beneficial in tauopathy is unclear. Here, we show that overexpressing an apoE metabolic receptor, LDLR (low-density lipoprotein receptor), in P301S tauopathy mice markedly reduces brain apoE and ameliorates tau pathology and neurodegeneration. LDLR overexpression (OX) in microglia cell-autonomously downregulates microglial Apoe expression and is associated with suppressed microglial activation as in apoE-deficient microglia. ApoE deficiency and LDLR OX strongly drive microglial immunometabolism toward enhanced catabolism over anabolism, whereas LDLR-overexpressing microglia also uniquely upregulate specific ion channels and neurotransmitter receptors upon activation. ApoE-deficient and LDLR-overexpressing mice harbor enlarged pools of oligodendrocyte progenitor cells (OPCs) and show greater preservation of myelin integrity under neurodegenerative conditions. They also show less reactive astrocyte activation in the setting of tauopathy.

Pituitary Adenoma in Pediatric and Adolescent Populations

Pituitary adenomas are rare in children and adolescents and although mostly benign, they can sometimes be challenging to manage due to their locally invasive nature. In this study, we examined the clinicopathologic features of 42 pituitary adenomas in patients ≤21 years of age. The youngest patient was 8 years old (median age: 18 years), and the female-to-male ratio was 1.8:1. Five patients had recurrence after resection. There was no obvious difference between the recurrent rates in the typical (11.7%) and atypical adenomas (12.5%) based on the 2004 WHO classification. However, the recurrence rate was much higher in adenomas with an elevated proliferation index of ≥3% (20.8%) or with evidence of local invasion (18.2%). Adenomas with combination of an elevated proliferation index of ≥3% and imaging evidence of local invasion had the highest recurrence rate of 25%. In summary, pituitary adenomas are more frequent in adolescents as compared with children and are more common in girls. An elevated proliferation index of ≥3% and evidence of local invasion on imaging seem to correlate with a high probability of recurrence. Furthermore, we observe rarity of α-thalassemia/mental retardation syndrome X-linked (ATRX) protein loss (surrogate to ATRX mutation) in these tumors without any connotation on prognosis.

Complex Patterns of GABAergic Neuronal Deficiency and Type 2 Potassium-Chloride Cotransporter Immaturity in Human Focal Cortical Dysplasia

Focal cortical dysplasia (FCD) is a common histopathologic finding in cortical specimens resected for refractory epilepsy. GABAergic neuronal abnormalities and K-Cl cotransporter type 2 (KCC2) immaturity may be contributing factors for FCD-related epilepsy. We examined surgical specimens from 12 cases diagnosed with FCD, and brain tissues without developmental abnormality obtained from 6 autopsy cases. We found that GABAergic neuronal density was abnormal in FCD with 2 distinct patterns. In 7 of 12 (58%) FCD subjects, the GABAergic neuron density in dysplastic regions and in neighboring nondysplastic regions was equally reduced, hence we call this a "broad pattern." In the remaining cases, GABAergic neuron density was decreased in dysplastic regions but not in the neighboring nondysplastic regions; we designate this "restricted pattern." The different patterns are not associated with pathologic subtypes of FCD. Intracytoplasmic retention of KCC2 is evident in dysmorphic neurons in the majority of FCD type II subjects (5/7) but not in FCD type I. Our study suggests that (1) "broad" GABAergic deficiency may reflect epileptic vulnerability outside the dysplastic area; and (2) abnormal distribution of KCC2 may contribute to seizure generation in patients with FCD type II but not in type I.

Loss- or Gain-of-Function Mutations in ACOX1 Cause Axonal Loss via Different Mechanisms

ACOX1 (acyl-CoA oxidase 1) encodes the first and rate-limiting enzyme of the very-long-chain fatty acid (VLCFA) β-oxidation pathway in peroxisomes and leads to H2O2 production. Unexpectedly, Drosophila (d) ACOX1 is mostly expressed and required in glia, and loss of ACOX1 leads to developmental delay, pupal death, reduced lifespan, impaired synaptic transmission, and glial and axonal loss. Patients who carry a previously unidentified, de novo, dominant variant in ACOX1 (p.N237S) also exhibit glial loss. However, this mutation causes increased levels of ACOX1 protein and function resulting in elevated levels of reactive oxygen species in glia in flies and murine Schwann cells. ACOX1 (p.N237S) patients exhibit a severe loss of Schwann cells and neurons. However, treatment of flies and primary Schwann cells with an antioxidant suppressed the p.N237S-induced neurodegeneration. In summary, both loss and gain of ACOX1 lead to glial and neuronal loss, but different mechanisms are at play and require different treatments.

In vivo evolution of biopsy-proven inflammatory demyelination quantified by R2t* mapping

A 35‐year‐old man with an enhancing tumefactive brain lesion underwent biopsy, revealing inflammatory demyelination. We used quantitative Gradient‐Recalled‐Echo (qGRE) MRI to visualize and measure tissue damage in the lesion. Two weeks after biopsy, qGRE showed significant R2t* reduction in the left optic radiation and surrounding tissue, consistent with the histopathological and clinical findings. qGRE was repeated 6 and 14 months later, demonstrating partially recovered optic radiation R2t*, in concert with improvement of the hemianopia to ultimately involve only the lower right visual quadrant. These results support qGRE metrics as in vivo biomarkers for tissue damage and longitudinal monitoring of demyelinating disease.

[Early recognition and screening consultation: a necessary way to improve early detection and treatment in rheumatology? : Overview of the early recognition and screening consultation models for rheumatic and musculoskeletal diseases in Germany]

In order to reduce the prognostically relevant time interval between the initial manifestation of a rheumatic and musculoskeletal disease and diagnosis as well as the consecutive initiation of an appropriate treatment, several rheumatological centers in Germany have improved the access to initial rheumatologic evaluation by establishing early recognition/screening clinics at their respective sites. Corresponding models located at Altoetting·Burghausen, Bad Pyrmont, Berlin Buch, Duesseldorf, Heidelberg, Herne, Mannheim as well as supraregional/multicenter initiatives Rheuma Rapid, RhePort and Rheuma-VOR are presented in this overview along with the respective characteristics, potential advantages and disadvantages, but also first evaluation results of several models. The aim of this publication is to promote early detection of rheumatic and musculoskeletal diseases as one of the most important challenges in current rheumatology by encouraging further rheumatologic centers and practices to launch their own early recognition/screening consultation model on the basis of aspects presented herein.

Diffusion basis spectrum imaging for identifying pathologies in MS subtypes

Diffusion basis spectrum imaging (DBSI) combines discrete anisotropic diffusion tensors and the spectrum of isotropic diffusion tensors to model the underlying multiple sclerosis (MS) pathologies. We used clinical MS subtypes as a surrogate of underlying pathologies to assess DBSI as a biomarker of pathology in 55 individuals with MS. Restricted isotropic fraction (reflecting cellularity) and fiber fraction (representing apparent axonal density) were the most important DBSI metrics to classify MS using brain white matter lesions. These DBSI metrics outperformed lesion volume. When analyzing the normal‐appearing corpus callosum, the most significant DBSI metrics were fiber fraction, radial diffusivity (reflecting myelination), and nonrestricted isotropic fraction (representing edema). This study provides preliminary evidence supporting the ability of DBSI as a potential noninvasive biomarker of MS neuropathology.

[Experiences and results from Rheuma-VOR]

Rheumatoid arthritis, psoriatic arthritis and axial spondylarthritis are the most common chronic autoimmune rheumatic diseases. For all three diseases an early diagnosis and initiation of treatment is crucial. The proof of concept network study "Rheuma-VOR" is a further developed version of the predecessor project ADAPTHERA and was extended to several federal states. The aim of this prospective study is to improve the early diagnosis of rheumatoid arthritis, psoriatic arthritis and axial spondylarthritis and thus positively impact the quality of care for patients with the help of multidisciplinary coordinating centers. To date 3710 disease-specific questionnaires from patients with the suspected diagnosis of rheumatoid arthritis, psoriatic arthritis or axial spondylarthritis from 1298 different primary care providers were registered in the multidisciplinary coordination centers. A total of 1958 appointments were made with 1 of the 53 participating rheumatology specialists. In 876 patients, 1 of the 3 rheumatic diseases was diagnosed in an early stage. The waiting period was on average 42.5 days depending on the federal state, which is well below the nationwide average. It should also be noted that the coordinated cooperation and risk stratification of the Rheuma-VOR coordination centers relieved the capacity of rheumatology specialists by 1281 appointments (34.5%). In addition, the 2‑week Rheuma Bus Tour and the accompanying initiatives in Rhineland-Palatinate (Rheuma-VOR screening app and the triage consultation) are showing first promising positive results.

Mitochondriopathy: The unifying concept in distal neuropathies?

This is a new, exciting time for the study of peripheral nerve and its diseases. For many years research in peripheral neuropathies largely involved descriptive analysis, a situation which is now rapidly giving way to hypothesis testing with the development and validation of molecular genetic tools. Although it has been known for some time that many neuropathies target the most distal portions of the longest peripheral nerves, a process variously referred to as central-peripheral distal neuropathy, "dying-back" neuropathy, or "stocking-glove" neuropathy, proposed mechanisms driving axon loss have been generally unproven/untestable. Studies have shown that mitochondrial DNA mutations accumulate in distal axons and a unifying theory of distal neuropathy has been proposed based on underlying mitochondrial aging defects in mitogenesis and, thus, distal axon susceptibility, particularly if axonal transport defects also accompanied them. Increased levels of mtDNA mutations have been described in some painful neuropathies (e.g., HIV) compared to baseline HIV patients and controls. For some time no therapies were available to preserve and prevent the development of peripheral neuropathy and, with a variety of expected pathogenetic mechanisms, complex cocktails of therapeutic agents were envisioned. Although structure and ultrastructure continue to be relevant in the studies of mitochondriopathy-driven neuropathies, more techniques have been added and more complex hypotheses now expand the concept and focus directly on mitochondrial pathology or dysfunction. It is now possible to definitively test possible pathogenetic mechanisms with a variety of new tools and to formulate new and testable hypotheses.

A mutation in Site-1 Protease is associated with a complex phenotype that includes episodic hyperCKemia and focal myoedema

Background

Site‐1 Protease (S1P) is a Golgi‐resident protein required for the activation of regulatory proteins that drive key cellular functions, including, the unfolded protein response (UPR) and lipid and cholesterol biosynthesis. While disruptions in S1P function have been widely characterized in animal models, to date, the implications of disrupted S1P function in human disease states are not completely known.

Methods

The patient and both parents underwent whole exome and mitochondrial DNA sequencing, and Sanger sequencing was used to confirm the mutation. Western blotting and immunofluorescence studies were performed on either proband‐derived fibroblasts or on an established cell line to assess protein expression and cellular localization of the mutated S1P protein. Quantitative real‐time PCR and luciferase reporter assays were used to examine activation of S1P target pathways in the context of the S1P mutation.

Results

We describe a female patient with a de novo heterozygous missense mutation in the transmembrane domain of S1P (p. Pro1003Ser). The patient presented to our neuromuscular clinic with episodic, activity‐induced, focal myoedema and myalgias with hyperCKemia. Her clinical phenotype was complex and included gastrointestinal hypomotility, ocular migraines, and polycystic ovary syndrome. Molecular analysis using proband‐derived fibroblasts and cell lines harboring the Pro1003Ser mutation demonstrated increased activation of UPR and lipid and cholesterol regulatory pathways and localization of S1P Pro1003Ser in the Golgi.

Conclusion

These findings suggest a critical function for S1P in several human organ systems and implicate an important role for S1P in various human disease states.

Progressive multifocal leukoencephalopathy treated with nivolumab

Therapy for progressive multifocal leukoencephalopathy (PML) remains challenging since there are no antiviral therapies available for JC virus. Immune reconstitution has improved the prognosis in many settings where PML occurs, but it often is not possible in PML patients with hematologic malignancies. We describe the first biopsy proven PML case where the PD-1 inhibitor nivolumab appears to have stimulated immune activation resulting in effective control of PML in a patient with hematologic malignancy. This report supports further investigation of the utility of checkpoint inhibitors for treating PML where other immune reconstitution options are not available.

Astrocytic degeneration in chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repeated head traumas. Using immunohistochemistry for glial fibrillary acidic protein as a marker, plus automated quantitative analysis, we examined the characteristics and extent of astrogliosis present in stage III and IV CTE, along with Alzheimer's disease (AD), and frontotemporal dementia (FTD) cases. Astrogliosis in CTE patients was more diffuse compared to that of AD and FTD patients, which was concentrated in the sulcal depths. Of 14 patients with CTE, 10 exhibited signs of a degenerating astrocyte pathology, characterized by beaded, broken astrocytic processes. This astrocytic degeneration was typically found to be diffuse throughout the white matter, although two cases demonstrated astrocytic degeneration in the gray matter. The degeneration was also observed in 2 of 3 AD and 2 of 3 FTD brains, with overall similar characteristics across diseases. There was minimal to no astrocytic degeneration in six age-matched controls with no neurodegenerative disease. We found that the extent of the white matter astrocytic degeneration was strongly correlated with the level of overall astrogliosis in both the white and gray matter. However, astrocytic degeneration was not correlated with the overall extent of tau pathology. Specifically, there was no correlation between levels of p-tau in the sulcal depths and astrocytic degeneration in the white matter adjacent to the sulcal depths. Thus, astrocytic degeneration and overall astrogliosis appear to represent distinct pathological features of CTE. Further investigation into these astroglial pathologies could provide new insights into underlying disease mechanisms and represent a potential target for in vivo assessment of CTE as well as other neurodegenerative disorders.

TREX1 is expressed by microglia in normal human brain and increases in regions affected by ischemia

Background

Mutations in the three‐prime repair exonuclease 1 (TREX1) gene have been associated with neurological diseases, including Retinal Vasculopathy with Cerebral Leukoencephalopathy (RVCL). However, the endogenous expression of TREX1 in human brain has not been studied.

Methods

We produced a rabbit polyclonal antibody (pAb) to TREX1 to characterize TREX1 by Western blotting (WB) of cell lysates from normal controls and subjects carrying an RVCL frame‐shift mutation. Dual staining was performed to determine cell types expressing TREX1 in human brain tissue. TREX1 distribution in human brain was further evaluated by immunohistochemical analyses of formalin‐fixed, paraffin‐embedded samples from normal controls and patients with RVCL and ischemic stroke.

Results

After validating the specificity of our anti‐TREX1 rabbit pAb, WB analysis was utilized to detect the endogenous wild‐type and frame‐shift mutant of TREX1 in cell lysates. Dual staining in human brain tissues from patients with RVCL and normal controls localized TREX1 to a subset of microglia and macrophages. Quantification of immunohistochemical staining of the cerebral cortex revealed that TREX1⁺ microglia were primarily in the gray matter of normal controls (22.7 ± 5.1% and 5.5 ± 1.9% of Iba1⁺ microglia in gray and white matter, respectively) and commonly in association with the microvasculature. In contrast, in subjects with RVCL, the TREX1⁺ microglia were predominantly located in the white matter of normal appearing cerebral cortex (11.8 ± 3.1% and 38.9 ± 5.8% of Iba1⁺ microglia in gray and white matter, respectively). The number of TREX1⁺ microglia was increased in ischemic brain lesions in central nervous system of RVCL and stroke patients.

Conclusions

TREX1 is expressed by a subset of microglia in normal human brain, often in close proximity to the microvasculature, and increases in the setting of ischemic lesions. These findings suggest a role for TREX1⁺ microglia in vessel homeostasis and response to ischemic injury.

A database of tissue-specific rhythmically expressed human genes has potential applications in circadian medicine

The discovery that half of the mammalian protein-coding genome is regulated by the circadian clock has clear implications for medicine. Recent studies demonstrated that the circadian clock influences therapeutic outcomes in human heart disease and cancer. However, biological time is rarely given clinical consideration. A key barrier is the absence of information on tissue-specific molecular rhythms in the human body. We have applied the cyclic ordering by periodic structure (CYCLOPS) algorithm, designed to reconstruct sample temporal order in the absence of time-of-day information, to the gene expression collection of 13 tissues from 632 human donors. We identified rhythms in gene expression across the body; nearly half of protein-coding genes were shown to be cycling in at least 1 of the 13 tissues analyzed. One thousand of these cycling genes encode proteins that either transport or metabolize drugs or are themselves drug targets. These results provide a useful resource for studying the role of circadian rhythms in medicine and support the idea that biological time might play a role in determining drug response.

Circadian Dysregulation: The Next Frontier in Obstructive Sleep Apnea Research

OBJECTIVE

To review the effects of the circadian clock on homeostasis, the functional interaction between the circadian clock and hypoxia-inducible factors, and the role of circadian dysregulation in the progression of cardiopulmonary disease in obstructive sleep apnea (OSA).

DATA SOURCES

The MEDLINE database was accessed through PubMed.

REVIEW METHODS

A general review is presented on molecular pathways disrupted in OSA, circadian rhythms and the role of the circadian clock, hypoxia signaling, crosstalk between the circadian and hypoxia systems, the role of the circadian clock in cardiovascular disease, and implications for practice. Studies included in this State of the Art Review demonstrate the potential contribution of the circadian clock and hypoxia in animal models or human disease.

CONCLUSIONS

Molecular crosstalk between the circadian clock and hypoxia-inducible factors has not been evaluated in disease models of OSA.

IMPLICATIONS FOR PRACTICE

Pediatric OSA is highly prevalent and, if left untreated, may lead to cardiopulmonary sequelae. Changes in inflammatory markers that normally demonstrate circadian rhythmicity are also seen among patients with OSA. Hypoxia-inducible transcription factors interact with core circadian clock transcription factors; however, the interplay between these pathways has not been elucidated in the cardiopulmonary system. This gap in knowledge hinders our ability to identify potential biomarkers of OSA and develop alternative therapeutic strategies. A deeper understanding of the mechanisms by which OSA impinges on clock function and the impact of clock dysregulation on the cardiopulmonary system may lead to future advancements for the care of patients with OSA. The aim of this review is to shed light on this important clinical topic.

Autoimmune Encephalitis With Multiple Autoantibodies: A Diagnostic and Therapeutic Challenge

INTRODUCTION

Indications for autoantibody testing in patients with rapid-onset cognitive impairment have expanded in step with the growing number of disease-associated autoantibodies and clinical syndromes. Although increased access to autoantibody testing has broadened our understanding of the spectrum of autoimmune encephalitis (AE), it has also produced new challenges associated with deciphering the contributions of disease-associated autoantibodies in patients with atypical clinical features and/or multiple autoantibodies. These challenges are illustrated through presentation of a patient with AE associated with autoantibodies against intracellular and cell-surface neuronal antigens. The implications of detection of multiple autoantibodies are considered in the context of relevant literature, and used to frame a diagnostic and therapeutic approach.

CASE REPORT

A previously well 67-year-old man presented with encephalopathy and psychosis, impaired visual fixation, and ataxia, emerging over 3 months. Hu, CRMP-5, and NMDAR autoantibodies were identified in the cerebrospinal fluid. No malignancy was discovered despite extensive investigations. An aggressive course of immunotherapy temporarily stabilized his course; however, the patient succumbed to his illness 10 months after symptom onset. Lack of sustained response to immunotherapy and neuropathologic findings suggested that AE associated with Hu antibodies was primarily responsible for this patient's progressive decline.

CONCLUSIONS

Multiple autoantibodies may be detected in patients with AE. When antibodies targeting intracellular and cell-surface antigens are detected together, investigation and treatment of syndromes associated with intracellular antibodies should be prioritized, acknowledging the link between these antibodies and irreversible neuronal injury. In paraneoplastic cases, prognosis may be tied to early detection and treatment of the underlying malignancy.

Histopathological correlation of diffusion basis spectrum imaging metrics of a biopsy-proven inflammatory demyelinating brain lesion: A brief report

Diffusion basis spectrum imaging (DBSI) models diffusion-weighted magnetic resonance imaging (MRI) signals as a combination of discrete anisotropic diffusion tensors and a spectrum of isotropic diffusion tensors. Here, we report the histopathological correlates of DBSI in the biopsied brain tissue of a patient with an inflammatory demyelinating lesion typical of multiple sclerosis (MS). Increased radial diffusivity (marker of demyelination), decreased fiber fraction (apparent axonal density), elevated nonrestricted isotropic fraction (marker of vasogenic edema), but unchanged axial diffusivity (marker of integrity of residual axons) seen in the lesion appeared consistent with histopathological findings of inflammatory demyelination with relative axonal sparing. Our report supports the application of DBSI as a biomarker in human studies of MS.

Occurrence of the large ostracod, Chlamydotheca unispinosa (Baird, 1862), in temporary waters of Montserrat, Lesser Antilles

Four populations of the large freshwater ostracod, Chlamydotheca unispinosa (Baird, 1862), were discovered on the Caribbean island of Montserrat. These are the first records of the species on Montserrat and extend its known distribution approximately 113 km northwest and 63 km southeast of the closest known populations on Îles des Saintes (Guadeloupe) and Nevis, respectively. We provide the first DNA barcode for C. unispinosa, a 686 bp fragment of the COI gene which may be used for future comparative studies of this widely distributed species.

Amyloid-β Plaques in Clinical Alzheimer's Disease Brain Incorporate Stable Isotope Tracer In Vivo and Exhibit Nanoscale Heterogeneity

Alzheimer's disease (AD) is a neurodegenerative disorder with clinical manifestations of progressive memory decline and loss of executive function and language. AD affects an estimated 5.3 million Americans alone and is the most common form of age-related dementia with a rapidly growing prevalence among the aging population-those 65 years of age or older. AD is characterized by accumulation of aggregated amyloid-beta (Aβ) in the brain, which leads to one of the pathological hallmarks of AD-Aβ plaques. As a result, Aβ plaques have been extensively studied after being first described over a century ago. Advances in brain imaging and quantitative measures of Aβ in biological fluids have yielded insight into the time course of plaque development decades before and after AD symptom onset. However, despite the fundamental role of Aβ plaques in AD, in vivo measures of individual plaque growth, growth distribution, and dynamics are still lacking. To address this question, we combined stable isotope labeling kinetics (SILK) and nanoscale secondary ion mass spectrometry (NanoSIMS) imaging in an approach termed SILK-SIMS to resolve plaque dynamics in three human AD brains. In human AD brain, plaques exhibit incorporation of a stable isotope tracer. Tracer enrichment was highly variable between plaques and the spatial distribution asymmetric with both quiescent and active nanometer sub-regions of tracer incorporation. These data reveal that Aβ plaques are dynamic structures with deposition rates over days indicating a highly active process. Here, we report the first, direct quantitative measures of in vivo deposition into plaques in human AD brain. Our SILK-SIMS studies will provide invaluable information on plaque dynamics in the normal and diseased brain and offer many new avenues for investigation into pathological mechanisms of the disease, with implications for therapeutic development.

Organ weights and histopathology of double-crested cormorants (Phalacrocorax auritus) dosed orally or dermally with artificially weathered Mississippi Canyon 252 crude oil

A series of toxicity tests were conducted to assess the effects of low to moderate exposure to artificially weathered Deepwater Horizon Mississippi Canyon 252 crude oil on representative avian species as part of the Natural Resource Damage Assessment. The present report summarizes effects of oral exposure (n=26) of double-crested cormorants (DCCO; Phalacrocorax auritus) to 5 or 10ml oil kg^-1 day^-1 for up to 21 days or dermal application (n=25) of 13ml oil to breast and back feathers every three days totaling 6 applications in 21 days on organ weights and histopathology. Absolute and relative kidney and liver weights were increased in birds exposed to oil. Additionally, gross and/or histopathologic lesions occurred in the kidney, heart, pancreas and thyroid. Clinically significant renal lesions in the orally dosed birds included squamous metaplasia and increased epithelial hypertrophy of the collecting ducts and renal tubules and mineralization in comparison to controls. Gross cardiac lesions including thin walls and flaccid musculature were documented in both orally and dermally dosed birds and myocardial fibrosis was found in low numbers of dermally dosed birds only. Cytoplasmic vacuolation of the exocrine pancreas was noted in orally dosed birds only. Thyroid follicular hyperplasia was increased in dermally dosed birds only possibly due to increased metabolism required to compensate damaged feather integrity and thermoregulate. Gastrointestinal ulceration was found in orally dosed birds only. There were no significant hepatic histopathologic lesions induced by either exposure route. Therefore, hepatic histopathology is likely not a good representation of oil-induced damage. Taken together, the results suggest that oral or dermal exposure of DCCOs to artificially weathered MC252 crude oil induced organ damage that could potentially affect survivability.

Effect of oral exposure to artificially weathered Deepwater Horizon crude oil on blood chemistries, hepatic antioxidant enzyme activities, organ weights and histopathology in western sandpipers (Calidris mauri)

Shorebirds were among birds exposed to Mississippi Canyon 252 (MC252) crude oil during the 2010 Deep Water Horizon (DWH) oil spill in the Gulf of Mexico. The western sandpiper (Calidris mauri) was chosen as one of four species for initial oral dosing studies conducted under Phase 2 of the avian toxicity studies for the DWH Natural Resource Damage Assessment (NRDA). Thirty western sandpipers were assigned to one of three treatment groups, 10 birds per group. The control group was sham gavaged and the treatment groups were gavaged with 1 or 5mL oil kg bw^-1 daily for 20 days. Periodic blood samples for hemoglobin measurements were collected during the trial. A final blood sample used to determine hemoglobin concentration in addition to complete blood counts, plasma clinical chemistries, haptoglobin concentration and plasma electrophoresis was collected when birds were euthanized and necropsied on day 21. Tissues were removed, weighed and processed for subsequent histopathological evaluation. There were numerical decreases in hemoglobin concentrations in oil-dosed birds over the 21-day trial, but values were not significantly different compared to controls on day 21. There were no significant differences between controls and oiled birds in complete blood counts, plasma chemistries, haptoglobin concentration, and plasma electrophoresis endpoints. Of the hepatic oxidative stress endpoints assessed, the total antioxidant capacity assessment (Trolox equivalents) for the control group was lower compared to the 1mL oil kg bw^-1 group. Absolute liver weights in the 5mL oil kg bw^-1 group were significantly greater compared to controls. While not conclusive, the numerical decrease in hemoglobin concentration and significant increase in absolute liver weight are consistent with exposure to oil. Histological changes in the adrenal gland could be considered a non-specific indicator of stress resulting from exposure to oil. It is possible that the quantity of oil absorbed was not sufficient to induce clearly evident hemolytic anemia or that the western sandpiper is relatively insensitive to ingested oil.

Survival among children with "Lethal" congenital contracture syndrome 11 caused by novel mutations in the gliomedin gene (GLDN)

Biallelic GLDN mutations have recently been identified among infants with lethal congenital contracture syndrome 11 (LCCS11). GLDN encodes gliomedin, a protein required for the formation of the nodes of Ranvier and development of the human peripheral nervous system. We report six infants and children from four unrelated families with biallelic GLDN mutations, four of whom survived beyond the neonatal period into infancy, childhood, and late adolescence with intensive care and chronic respiratory and nutritional support. Our findings expand the genotypic and phenotypic spectrum of LCCS11 and demonstrate that the condition may not necessarily be lethal in the neonatal period.

Ventricular Zone Disruption in Human Neonates With Intraventricular Hemorrhage

To determine if ventricular zone (VZ) and subventricular zone (SVZ) alterations are associated with intraventricular hemorrhage (IVH) and posthemorrhagic hydrocephalus, we compared postmortem frontal and subcortical brain samples from 12 infants with IVH and 3 nonneurological disease controls without hemorrhages or ventriculomegaly. Birth and expiration estimated gestational ages were 23.0-39.1 and 23.7-44.1 weeks, respectively; survival ranges were 0-42 days (median, 2.0 days). Routine histology and immunohistochemistry for neural stem cells (NSCs), neural progenitors (NPs), multiciliated ependymal cells (ECs), astrocytes (AS), and cell adhesion molecules were performed. Controls exhibited monociliated NSCs and multiciliated ECs lining the ventricles, abundant NPs in the SVZ, and medial vs. lateral wall differences with a complex mosaic organization in the latter. In IVH cases, normal VZ/SVZ areas were mixed with foci of NSC and EC loss, eruption of cells into the ventricle, cytoplasmic transposition of N-cadherin, subependymal rosettes, and periventricular heterotopia. Mature AS populated areas believed to be sites of VZ disruption. The cytopathology and extension of the VZ disruption correlated with developmental age but not with brain hemorrhage grade or location. These results corroborate similar findings in congenital hydrocephalus in animals and humans and indicate that VZ disruption occurs consistently in premature neonates with IVH.

Unusual high-grade features in pediatric diffuse leptomeningeal glioneuronal tumor: comparison with a typical low-grade example

Diffuse leptomeningeal glioneuronal tumor, a recent addition to the World Health Organization classification system, typically presents in the pediatric population with signs and symptoms related to elevated intracranial pressure and imaging characteristics that may mimic infectious etiologies. The tumor is usually low grade and tends to harbor BRAF rearrangement/duplication in up to 75% of cases, BRAF V600E mutation in a smaller subset of cases, and loss of chromosomal arm 1p in approximately 50%-60% of cases, with ~20% of those showing loss of both 1p and 19q (codeletion). We report here 2 contrasting cases of diffuse leptomeningeal glioneuronal tumors, one with typical low-grade features and an indolent, although not benign, course, in which the disease is currently successfully managed by chemotherapy, and a second case with unusually high-grade features on initial presentation, including frank anaplasia and elevated mitotic index, in which the disease showed an initial response to chemoradiation but ultimately was fatal.

Gymnophthalmus underwoodi Grant, 1958 (Reptilia: Gymnophthalmidae), a new record for the island of Montserrat

Two species of gymnophthalmids are known to inhabit islands in the West Indies, the unisexual Gymnophthalmus underwoodi Grant, 1958 and the bisexual G. pleii Bocourt, 1881, but neither has been previously recorded on Montserrat. Small microteiid lizards were observed between 2008 and 2016 at 5 locations on Montserrat. Scale counts and mitochondrial 16S rDNA sequences of specimens confirmed them to be G. underwoodi. The widespread distribution of this ninth lizard species on Montserrat suggests that it has gone undetected for some time or has rapidly colonized the island.

Can anti-vascular endothelial growth factor antibody reverse radiation necrosis? A preclinical investigation

Anti-vascular endothelial growth factor (anti-VEGF) antibodies are a promising new treatment for late time-to-onset radiation-induced necrosis (RN). We sought to evaluate and validate the response to anti-VEGF antibody in a mouse model of RN. Mice were irradiated with the Leksell Gamma Knife Perfexion™ and then treated with anti-VEGF antibody, beginning at post-irradiation (PIR) week 8. RN progression was monitored via anatomic and diffusion MRI from weeks 4-12 PIR. Standard histology, using haematoxylin and eosin (H&E), and immunohistochemistry staining were used to validate the response to treatment. After treatment, both post-contrast T1-weighted and T2-weighted image-derived lesion volumes decreased (P < 0.001), while the lesion volumes for the control group increased. The abnormally high apparent diffusion coefficient (ADC) for RN also returned to the ADC range for normal brain following treatment (P < 0.001). However, typical RN pathology was still present histologically. Large areas of focal calcification were observed in ~50% of treated mouse brains. Additionally, VEGF and hypoxia-inducible factor 1-alpha (HIF-1α) were continually upregulated in both the anti-VEGF and control groups. Despite improvements observed radiographically following anti-VEGF treatment, lesions were not completely resolved histologically. The subsequent calcification and the continued upregulation of VEGF and HIF-1α merit further preclinical/clinical investigation.

Variation in seminal plasma alters the ability of ram spermatozoa to survive cryopreservation

Variation in the effect of seminal plasma on sperm function and fertility has been hypothesised to be due to differences between males and their seminal plasma composition. The freezing resilience of individual rams (n=17) was investigated to characterise inter-male variation. This was determined by measuring the degree of change in motility induced by cryopreservation (Experiment 1). Experiment 2 examined the effect of pooled seminal plasma from rams identified as having high or low resilience to freezing on the cryosurvival of washed spermatozoa from either high (n=3) or low (n=3) sperm freezing resilience rams. Immediately after thawing and throughout the incubation period (0-4h), spermatozoa from high-resilience rams frozen with high-resilience seminal plasma demonstrated superior motility to spermatozoa from high-resilience rams frozen with low-resilience seminal plasma (P<0.001). Similarly, spermatozoa from low-resilience rams frozen with high-resilience seminal plasma exhibited higher motility than spermatozoa from low-resilience rams frozen with low-resilience seminal plasma immediately after thawing (0h; P<0.001). The present study shows that variation in freezing resilience of ram spermatozoa is related to the source and composition of the seminal plasma.

Diffusion MRI quantifies early axonal loss in the presence of nerve swelling

Background

Magnetic resonance imaging markers have been widely used to detect and quantify white matter pathologies in multiple sclerosis. We have recently developed a diffusion basis spectrum imaging (DBSI) to distinguish and quantify co-existing axonal injury, demyelination, and inflammation in multiple sclerosis patients and animal models. It could serve as a longitudinal marker for axonal loss, a primary cause of permanent neurological impairments and disease progression.

Methods

Eight 10-week-old female C57BL/6 mice underwent optic nerve DBSI, followed by a week-long recuperation prior to active immunization for experimental autoimmune encephalomyelitis (EAE). Visual acuity of all mice was assessed daily. Longitudinal DBSI was performed in mouse optic nerves at baseline (naïve, before immunization), before, during, and after the onset of optic neuritis. Tissues were perfusion fixed after final in vivo scans. The correlation between DBSI detected pathologies and corresponding immunohistochemistry markers was quantitatively assessed.

Results

In this cohort of EAE mice, monocular vision impairment occurred in all animals. In vivo DBSI detected, differentiated, and quantified optic nerve inflammation, demyelination, and axonal injury/loss, correlating nerve pathologies with visual acuity at different time points of acute optic neuritis. DBSI quantified, in the presence of optic nerve swelling, ~15% axonal loss at the onset of optic neuritis in EAE mice.

Conclusions

Our findings support the notion that axonal loss could occur early in EAE mice. DBSI detected pathologies in the posterior visual pathway unreachable by optical coherence tomography and without confounding inflammation induced optic nerve swelling. DBSI could thus decipher the interrelationship among various pathological components and the role each plays in disease progression. Quantification of the rate of axonal loss could potentially serve as the biomarker to predict treatment outcome and to determine when progressive disease starts.