Infantile Rosai-Dorfman Disease With Isolated Brain Lesions Disseminated to the Parenchyma and Intraventricular Ependyma, Alteration of Leukocytes as a Promotion Factor in Immune Defense, and New Proposals: A Case Report and Literature Review

The patient is a one-year-old girl referred to the hospital for an enlarged head after a 1.5-month history of two falls, followed by polydipsia, polyuria, and slow movement and growth. Three subsequent magnetic resonance imaging (MRI) examinations of the brain revealed nodular lesions disseminated in the brain parenchyma and intraventricular ependyma, resulting in obstructive hydrocephalus. Thoracic and abdominopelvic sonography showed no additional lesions. The preliminary diagnosis was a primary or metastatic neoplasm or infection. A biopsy of a lesion in the right frontal lobe was taken. The histological examination revealed features of Rosai-Dorfman disease (RDD), consisting of limited perivascular lymphoplasma cell infiltration with intervening sheets of proliferated histiocytes, with some of the histiocytes showing endocytosis of a single intact lymphocyte (emperipolesis).

Fully automated measurement of intracranial CSF and brain parenchyma volumes in pediatric hydrocephalus by segmentation of clinical MRI studies

BACKGROUND

Brain parenchyma (BP) and intracranial cerebrospinal fluid (iCSF) volumes measured by fully automated segmentation of clinical brain MRI studies may be useful for the diagnosis and follow-up of pediatric hydrocephalus. However, previously published segmentation techniques either rely on dedicated sequences, not routinely used in clinical practice, or on spatial normalization, which has limited accuracy when severe brain distortions, such as in hydrocephalic patients, are present.

PURPOSE

We developed a fully automated method to measure BP and iCSF volumes from clinical brain MRI studies of pediatric hydrocephalus patients, exploiting the complementary information contained in T2- and T1-weighted images commonly used in clinical practice.

METHODS

The proposed procedure, following skull-stripping of the combined volumes, performed using a multiparametric method to obtain a reliable definition of the inner skull profile, maximizes the CSF-to-parenchyma contrast by dividing the T2w- by the T1w- volume after full-scale dynamic rescaling, thus allowing separation of iCSF and BP through a simple thresholding routine.

RESULTS

Validation against manual tracing on 23 studies (four controls and 19 hydrocephalic patients) showed excellent concordance (ICC > 0.98) and spatial overlap (Dice coefficients ranging from 77.2% for iCSF to 96.8% for intracranial volume). Accuracy was comparable to the intra-operator reproducibility of manual segmentation, as measured in 14 studies processed twice by the same experienced neuroradiologist. Results of the application of the algorithm to a dataset of 63 controls and 57 hydrocephalic patients (19 with parenchymal damage), measuring volumes' changes with normal development and in hydrocephalic patients, are also reported for demonstration purposes.

CONCLUSIONS

The proposed approach allows fully automated segmentation of BP and iCSF in clinical studies, also in severely distorted brains, enabling to assess age- and disease-related changes in intracranial tissue volume with an accuracy comparable to expert manual segmentation.

Towards an Understanding of Microglia and Border-Associated Macrophages

The central nervous system (CNS) plays a crucial role in regulating bodily functions by sensing and integrating environmental cues and maintaining proper physiological conditions. Recent research has revealed that CNS functions are closely coordinated with the immune system. As even minor disturbances of the immune system in the CNS can lead to various dysfunctions, diseases, or even death, it is highly specialized and segregated from that in peripheral regions. Microglia in the parenchyma and macrophages at the interface between the CNS and peripheral regions are essential immune cells in the CNS that monitor environmental changes. Recent omics analyses have revealed that these cells exhibit highly heterogeneous populations. In this review, we summarize the functions and diversity of microglia in the brain parenchyma and those of macrophages in the border regions, such as the meninges, perivascular spaces, and choroid plexus.

Anatomical barriers against SARS-CoV-2 neuroinvasion at vulnerable interfaces visualized in deceased COVID-19 patients

Can SARS-CoV-2 hitchhike on the olfactory projection and take a direct and short route from the nose into the brain? We reasoned that the neurotropic or neuroinvasive capacity of the virus, if it exists, should be most easily detectable in individuals who died in an acute phase of the infection. Here, we applied a postmortem bedside surgical procedure for the rapid procurement of tissue, blood, and cerebrospinal fluid samples from deceased COVID-19 patients infected with the Delta, Omicron BA.1, or Omicron BA.2 variants. Confocal imaging of sections stained with fluorescence RNAscope and immunohistochemistry afforded the light-microscopic visualization of extracellular SARS-CoV-2 virions in tissues. We failed to find evidence for viral invasion of the parenchyma of the olfactory bulb and the frontal lobe of the brain. Instead, we identified anatomical barriers at vulnerable interfaces, exemplified by perineurial olfactory nerve fibroblasts enwrapping olfactory axon fascicles in the lamina propria of the olfactory mucosa.

Case report: IgG4-related intracranial lesions mimicking multiple sclerosis in a 14-year-old girl

Objectives

IgG4-related disease (IgG4-RD) is distinguished by the infiltration of IgG4-positive plasma cells in a variety of tissues and organs. Even so, central nervous system lesions associated with IgG4-RD are scarce. We present a case of IgG4-related brain parenchymal lesions that mimics multiple sclerosis in a young girl.

Methods

The patient was followed by our neurology and rheumatology teams. Clinical information was recorded, and the brain was screened using magnetic resonance imaging (MRI). During follow-up, we examined serum IgE, IgG and IgG4 and lymph node biopsy.

Results

Here, we presented details of a 14-year-old Chinese girl suffering from diplopia, left eyelid ptosis, right facial numbness, and right lower limb weakness admitted to our institute. Brain MRI revealed multiple sclerosis-like lesions in the brain parenchyma and spinal cord. During the follow-up, she developed lymphadenopathy. Elevation of serum, IgG, IgG4 and IgE and lymph node biopsy favors a diagnosis of IgG4-RD. The patient had a good response to glucocorticoids and mycophenolate mofetil. The literature review summarized eight previously reported IgG4-RD involving brain parenchyma.

Discussion

Our case expands the known age spectrum of IgG4-RD. The intracranial IgG4-RD is rare and could mimic multiple sclerosis. Careful examination and dynamic review of disease history are crucial in the differential diagnosis.

Magnetic resonance elastography to study the effect of amyloid plaque accumulation in a mouse model

BACKGROUND AND PURPOSE

Biomechanical changes in the brain have not been fully elucidated in Alzheimer's disease (AD). We aimed to investigate the effect of β-amyloid accumulation on mouse brain viscoelasticity.

METHODS

Magnetic resonance elastography was used to calculate magnitude of the viscoelastic modulus (|G*|), elasticity (G_d ), and viscosity (G_l ) in the whole brain parenchyma (WB) and bilateral hippocampi of 9 transgenic J20 (AD) mice (5 males/4 females) and 10 wild-type (WT) C57BL/6 mice (5 males/5 females) at 11 and 14 months of age.

RESULTS

Cross-sectional analyses showed no significant difference between AD and WT mice at either timepoints. No sex-specific differences were observed at 11 months of age, but AD females showed significantly higher hippocampal |G*| and G_l and WB |G*|, G_d , and G_l compared to both AD and WT males at 14 months of age. Similar trending differences were found between female AD and female WT animals but did not reach significance. Longitudinal analyses showed significant increases in hippocampal |G*|, G_d , and G_l , and significant decreases in WB |G*|, G_d , and G_l between 11 and 14 months in both AD and WT mice. Each subgroup showed significant increases in all hippocampal and significant decreases in all WB measures, with the exception of AD females, which showed no significant changes in WB |G*|, G_d , or G_l .

CONCLUSION

Aging had region-specific effects on cerebral viscoelasticity, namely, WB softening and hippocampal stiffening. Amyloid plaque deposition may have sex-specific effects, which require further scrutiny.

IgG4-Related Disease Complicated by Brain Parenchymal Lesions Successfully Treated with Corticosteroid Therapy: A Case Report

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is distinguished by the infiltration of IgG4-positive plasma cells in a variety of tissues and organs including the pancreas, salivary glands, retroperitoneal lesions, kidney, and lymph nodes with elevated serum IgG4 levels. Even so, central nervous system (CNS) lesions such as brain parenchymal lesions associated with IgG4-RD are scarce. So far, only six cases of IgG4-RD in relation with brain parenchymal lesions have been described, with its characteristics still being not clear. Here we have detailed a case of IgG4-RD with brain parenchymal lesions and reviewed previously-reported cases of IgG4-RD with brain parenchymal lesions. A 62-year-old Japanese male suffering from lung silicosis was admitted to our hospital for abdominal discomfort and altered consciousness. He has shown no major neurologic abnormalities except for drowsiness, urinary retention, and fecal incontinence. Brain magnetic resonance imaging has shown scattered hyperintense signals in the brain parenchyma. The serum IgG4 levels were elevated and systemic lymph nodes were enlarged. Biopsy from inguinal lymph nodes has shown massive infiltration of IgG4-positive plasma cells: the ratio of IgG4-positive/IgG-positive plasma cells was nearly 100%. Based on clinical courses, images, laboratory data, and pathological findings, a diagnosis of IgG4-RD that was complicated by brain parenchymal lesions and sacral nerve disturbance was confirmed. The patient was then given methylprednisolone pulse therapy (1g for 3 days) succeeding oral prednisolone (1 mg per body weight). The clinical and radiological improvements together with steroid therapy proposed IgG4-RD to be the cause of the lesions.

Current Techniques for Investigating the Brain Extracellular Space

The brain extracellular space (ECS) is a continuous reticular compartment that lies between the cells of the brain. It is vast in extent relative to its resident cells, yet, at the same time the nano- to micrometer dimensions of its channels and reservoirs are commonly finer than the smallest cellular structures. Our conventional view of this compartment as largely static and of secondary importance for brain function is rapidly changing, and its active dynamic roles in signaling and metabolite clearance have come to the fore. It is further emerging that ECS microarchitecture is highly heterogeneous and dynamic and that ECS geometry and diffusional properties directly modulate local diffusional transport, down to the nanoscale around individual synapses. The ECS can therefore be considered an extremely complex and diverse compartment, where numerous physiological events are unfolding in parallel on spatial and temporal scales that span orders of magnitude, from milliseconds to hours, and from nanometers to centimeters. To further understand the physiological roles of the ECS and identify new ones, researchers can choose from a wide array of experimental techniques, which differ greatly in their applicability to a given sample and the type of data they produce. Here, we aim to provide a basic introduction to the available experimental techniques that have been applied to address the brain ECS, highlighting their main characteristics. We include current gold-standard techniques, as well as emerging cutting-edge modalities based on recent super-resolution microscopy. It is clear that each technique comes with unique strengths and limitations and that no single experimental method can unravel the unknown physiological roles of the brain ECS on its own.

CORM-3 Regulates Microglia Activity, Prevents Neuronal Injury, and Improves Memory Function During Radiation-induced Brain Injury

OBJECTIVE

This study aims to explore in detail, the mechanism of the carbon monoxide releasing molecule-3 (CORM-3) in regulating the activity of microglia (MG) in the treatment of radiation brain injury (RBI).

METHODS

The brain injury models of BV2 cells and Balb/C mice were established and randomly divided into three groups: the normal control group (CON), the single radiation group (RAD), and the radiation plus CORM-3 intervention group (RAD+CORM). Immunofluorescence was used to observe the effects on activation of the MG. The expressions of inflammatory factors, such as intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS), were detected by Western blot. Neuron apoptosis and regeneration in the radiation brain injury (RBI) model were detected by neuronal nuclear antigen (NeuN)+TUNEL and NeuN+BrdU double staining. A Morris water maze was used to assess the spatial learning and memory of the mice.

RESULTS

Within 48 h after radiation, CORM-3 inhibited activation of the MG, blocked the phosphorylation of P38, and increased the expression of ICAM-1 and iNOS. Therefore, CORM-3 might alleviate MG-mediated neuronal apoptosis and promote neural regeneration in the subgranular zone (SGZ) of the dentate gyrus of the hippocampus. CORM-3 could increase the swimming distance and platform-stay time of the mice in the target platform quadrant after radiation.

CONCLUSION

CORM-3 could effectively improve the inflammatory response induced by activation of the MG, reduce neuronal apoptosis, promote neural regeneration, and improve the learning and memory performance of mice after radiation.

Osmotic pressure of serum and cerebrospinal fluid in patients with suspected neurological conditions

Interstitial fluid movement in the brain parenchyma has been suggested to contribute to sustaining the metabolism in brain parenchyma and maintaining the function of neurons and glial cells. The pulsatile hydrostatic pressure gradient may be one of the driving forces of this bulk flow. However, osmotic pressure-related factors have not been studied until now. In this prospective observational study, to elucidate the relationship between osmolality (mOsm/kg) in the serum and that in the cerebrospinal fluid (CSF), we simultaneously measured the serum and CSF osmolality of 179 subjects with suspected neurological conditions. Serum osmolality was 283.6 ± 6.5 mOsm/kg and CSF osmolality was 289.5 ± 6.6 mOsm/kg. Because the specific gravity of serum and CSF is known to be 1.024–1.028 and 1.004–1.007, respectively, the estimated average of osmolarity (mOsm/L) in the serum and CSF covered exactly the same range (i.e., 290.5–291.5 mOsm/L). There was strong correlation between CSF osmolality and serum osmolality, but the difference in osmolality between serum and CSF was not correlated with serum osmolality, serum electrolyte levels, protein levels, or quotient of albumin. In conclusion, CSF osmolarity was suggested to be equal to serum osmolarity. Osmolarity is not one of the driving forces of this bulk flow. Other factors such as hydrostatic pressure gradient should be used to explain the mechanism of bulk flow in the brain parenchyma. This study was approved by the Institutional Review Board of the Tohoku University Hospital (approval No. IRB No. 2015-1-257) on July 29, 2015.

Measurement of microvascular cerebral blood volume changes over the cardiac cycle with ferumoxytol-enhanced T2 * MRI

PURPOSE

This feasibility study investigates the non-invasive measurement of microvascular cerebral blood volume (BV) changes over the cardiac cycle using cardiac-gated, ferumoxytol-enhanced T 2 ∗ MRI.

METHODS

Institutional review board approval was obtained and all subjects provided written informed consent. Cardiac gated MR scans were prospectively acquired on a 3.0T scanner in 22 healthy subjects using T 2 ∗ -weighted sequences with 2D-EPI and 3D spiral trajectories. Images were collected before and after the intravenous administration of 2 doses of ferumoxytol (1 mg FE/kg and 4 mg FE/kg). Cardiac cycle-induced R 2 ∗ (1/ T 2 ∗ ) changes (Δ R 2 ∗ ) and BV changes (ΔBV) throughout the cardiac cycle in gray matter (GM) and white matter (WM) were quantified and differences assessed using ANOVA followed by post hoc analysis.

RESULTS

Δ R 2 ∗ was found to increase in a dose-dependent fashion. A significantly larger increase was observed in GM compared to WM in both 2D and 3D acquisitions (P < 0.050). In addition, Δ R 2 ∗ increased significantly (P < 0.001) post versus pre-contrast injection in GM in both T 2 ∗ MRI acquisitions. Mean GM Δ R 2 ∗ derived from 2D-EPI images was 0.14 ± 0.06 s^-1 pre-contrast and 0.33 ± 0.13 s^-1 after 5 mg FE/kg. In WM, Δ R 2 ∗ was 0.19 ± 0.06 s^-1 pre-contrast, and 0.23 ± 0.06 s^-1 after 5 mg FE/kg. The fractional changes in BV throughout the cardiac cycle were 0.031 ± 0.019% in GM and 0.011 ± 0.008% in WM (P < 0.001) after 5 mg FE/kg.

CONCLUSION

Cardiac-gated, ferumoxytol-enhanced T 2 ∗ MRI enables characterization of microvascular BV changes throughout the cardiac cycle in GM and WM tissue of healthy subjects.

Leukemia-derived exosomes and cytokines pave the way for entry into the brain

Infiltration of acute lymphoblastic leukemia (ALL) blasts into the CNS remains as a major clinical problem, with high risk for chemotherapy-resistant relapse and treatment-related morbidity. Despite the common inclusion of CNS prophylaxis treatments in therapy regimens, there are significant gaps in understanding the mechanisms that mediate leukemia cell entry into the CNS as well as roles for resident cells in the brain. In this study, we employ a xenograft model of human B cell precursor (BCP)-ALL in immunocompromised mice. This model system recapitulates key pathological characteristics of leptomeningeal involvement seen in patients and provides insights into rare cases that involve parenchymal invasion. We examine the infiltration of engrafted leukemia blasts into brains of recipient mice and provide evidence that the interaction between blasts and brain resident cells causes aberrant activation of host cells in the brain microenvironment. BCP-ALL blasts also release multiple cytokines and exosomes containing IL-15 that bind and are internalized by astrocytes and brain vessel endothelial cells. Leukemic invasion is linked to production of VEGF-AA by astrocytes and disruption of the blood-brain-barrier (BBB) integrity. Knockdown of either IL-15 or IL-15Rα in the NALM6 cell line decreases CNS infiltration in engrafted mice. These results provide important insights into the multiple mechanisms by which lymphoblasts modulate the brain microenvironment to breach the BBB for metastatic invasion.

Semi-Mechanistic Population Pharmacokinetic Modeling of L-Histidine Disposition and Brain Uptake in Wildtype and Pht1 Null Mice

PURPOSE

To develop a semi-mechanistic population pharmacokinetic (PK) model to quantitate the disposition kinetics of L-histidine, a peptide-histidine transporter 1 (PHT1) substrate, in the plasma, cerebrospinal fluid and brain parenchyma of wildtype (WT) and Pht1 knockout (KO) mice.

METHODS

L-[¹⁴C]Hisidine (L-His) was administrated to WT and KO mice via tail vein injection, after which plasma, cerebrospinal fluid (CSF) and brain parenchyma samples were collected. A PK model was developed using non-linear mixed effects modeling (NONMEM). The disposition of L-His between the plasma, brain, and CSF was described by a combination of PHT1-mediated uptake, CSF bulk flow and first-order micro-rate constants.

RESULTS

The PK profile of L-His was best described by a four-compartment model. A more rapid uptake of L-His in brain parenchyma was observed in WT mice due to PHT1-mediated uptake, a process characterized by a Michaelis-Menten component (V_max = 0.051 nmoL/min and K_m = 34.94 μM).

CONCLUSIONS

A semi-mechanistic population PK model was successfully developed, for the first time, to quantitatively characterize the disposition kinetics of L-His in brain under in vivo conditions. This model may prove a useful tool in predicting the uptake of L-His, and possibly other PHT1 peptide/mimetic substrates, for drug delivery to the brain.

Molecular insights into melanoma brain metastases

Substantial proportions of patients with metastatic melanoma develop brain metastases during the course of their disease, often resulting in significant morbidity and death. Despite recent advances with BRAF/MEK and immune-checkpoint inhibitors in the treatment of patients who have melanoma with extracerebral metastases, patients who have melanoma brain metastases still have poor overall survival, highlighting the need for further therapy options. A deeper understanding of the molecular pathways involved in the development of melanoma brain metastases is required to develop more brain-specific therapies. Here, the authors summarize the currently known preclinical data and describe steps involved in the development of melanoma brain metastases. Only by knowing the molecular background is it possible to design new therapeutic agents that can be used to improve the outcome of patients with melanoma brain metastases. Cancer 2017;123:2163-75. © 2017 American Cancer Society.

Diffuse Encephalopathy Associated with Isolated Cerebral Langerhans Cell Histiocytosis

BACKGROUND

Langerhans cell histiocytosis is a rare disease of the monocyte-macrophage system. Abnormalities of the hypothalamic-pituitary region are common in individuals with central nervous system involvement.

PATIENT DESCRIPTION

This six-year-old boy developed rapidly progressive aggressive behavior, central diabetes insipidus, and repeated complex partial seizures. Magnetic resonance imaging revealed a diffuse leukoencephalopathy-like pattern and numerous infratentorial and supratentorial granulomatous nodules in the brain parenchyma along with infundibular and hypothalamic mass lesions. Stereotactic serial biopsies enabled histopathologic and immunohistochemical diagnosis of Langerhans cell histiocytosis.

CONCLUSIONS

Similar MRI findings have rarely been described in the literature. These findings represent part of the broad neuroradiological spectrum of Langerhans cell histiocytosis of the nervous system in children.

Dissection of the Process of Brain Metastasis Reveals Targets and Mechanisms for Molecular-based Intervention

Brain metastases outnumber the incidence of brain tumors by a factor of ten. Patients with brain metastases have a dismal prognosis and current treatment modalities achieve only a modest clinical benefit. We discuss the process of brain metastasis with respect to mechanisms and involved targets to outline options for therapeutic intervention and focus on breast and lung cancer, as well as melanoma. We describe the process of penetration of the blood-brain-barrier (BBB) by disseminated tumor cells, establishment of a metastatic niche, colonization and outgrowth in the brain parenchyma. Furthermore, the role of angiogenesis in colonization of the brain parenchyma, interactions of extravasated tumor cells with microglia and astrocytes, as well as their propensity for neuromimicry, is discussed. We outline targets suitable for prevention of metastasis and summarize targets suitable for treatment of established brain metastases. Finally, we highlight the implications of findings revealing druggable mutations in brain metastases that cannot be identified in matching primary tumors.

Temporal effects of vascular endothelial growth factor and 3,5-cyclic monophosphate on blood-brain barrier solute permeability in vivo

To test the hypothesis that vascular endothelial growth factor (VEGF) can transiently increase the blood-brain barrier permeability, P, as for peripheral microvessels and that the elevation of 3,5-cyclic monophosphate (cAMP) levels can inhibit the VEGF-induced acute hyperpermeability, we employed multiphoton microscopy to quantify the cerebral microvessel permeability P to various-sized solutes under VEGF and cAMP treatments. The cerebral microcirculation was observed through a section of frontoparietal bone thinned with a microgrinder. Fluorescein (MW 376Da), fluorescein isothioyanate-dextran-20k (FITC-Dex-20k), FITC-Dex-70k, or Alexa Fluor 488-IgG in 1% bovine serum albumin mammalian Ringer's solution was injected into the cerebral circulation via the ipsilateral carotid artery with a syringe pump. Simultaneously, temporal images were collected from the brain parenchyma ∼100-200 μm below the pia mater. P was determined from the rate of tissue solute accumulation around individual microvessels. Exposure to 1 nM VEGF transiently increased P to 2.2, 10.5, 9.8, and 12.8 times control values, for fluorescein, Dex-20k, Dex-70k, and IgG, respectively, within 30 sec, and all returned to control levels within 2 min. After 20 min of pretreatment with 2 mM of the cAMP analog 8-bromo-cAMP, the initial increase by 1 nM VEGF was completely abolished in P of all solutes. The response pattern of P to VEGF and cAMP and the ratios of the peak to control values for rat cerebral microvessels are similar to those for rat mesenteric (peripheral) microvessels, except that the ratios are higher in P of cerebral microvessels for the intermediate and large solutes. These results imply a new approach for delivering large therapeutic agents to the brain.