Leptomeningeal Carcinomatosis in Chronic Lymphocytic Leukemia: A Case Report and Review of the Literature.

Leptomeningeal disease is a rare complication of chronic lymphocytic leukemia (CLL). We report a case of leptomeningeal disease in CLL with a complete clinical response and clearance of cerebral spinal fluid (CSF) after treatment with ibrutinib and intrathecal rituximab. In a comprehensive review of the published literature since 1976, we found 136 cases of CLL with leptomeningeal spread. We found that leptomeningeal disease in patients with CLL responds favorably to treatment in most cases and is associated with longer overall survival than is expected for other cancers. Clearance of CSF is associated with improved survival. Treatment with rituximab and ibrutinib is more frequently associated with complete response compared with older agents. IMPLICATIONS FOR PRACTICE: The incidence of leptomeningeal CLL is more common than previously described and can be recognized by attention to certain symptoms and signs. This case presentation and literature review reveals that, in many cases, leptomeningeal lymphomatosis is reversible with the use of rituximab and ibrutinib. The authors show a survival benefit associated with treating to cerebral spinal fluid (CSF) clearance by cytology and compare outcomes with various treatment strategies, focusing on novel agents. Now that there is effective therapy for leptomeningeal lymphoma in CLL, the importance for oncologists to recognize this neurologic complication has become clear.

Genetic rescue of CB1 receptors on medium spiny neurons prevents loss of excitatory striatal synapses but not motor impairment in HD mice.

Huntington's disease (HD) is caused by an expanded polyglutamine repeat in huntingtin protein that disrupts synaptic function in specific neuronal populations and results in characteristic motor, cognitive and affective deficits. Histopathological hallmarks observed in both HD patients and genetic mouse models include the reduced expression of synaptic proteins, reduced medium spiny neuron (MSN) dendritic spine density and decreased frequency of spontaneous excitatory post-synaptic currents (sEPSCs). Early down-regulation of cannabinoid CB1 receptor expression on MSN (CB1(MSN)) is thought to participate in HD pathogenesis. Here we present a cell-specific genetic rescue of CB1(MSN) in R6/2 mice and report that treatment prevents the reduction of excitatory synaptic markers in the striatum (synaptophysin, vGLUT1 and vGLUT2), of dendritic spine density on MSNs and of MSN sEPSCs, but does not prevent motor impairment. We conclude that loss of excitatory striatal synapses in HD mice is controlled by CB1(MSN) and can be uncoupled from the motor phenotype.

Two novel mutations in ABHD12: expansion of the mutation spectrum in PHARC and assessment of their functional effects.

PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataracts) is a recently described autosomal-recessive neurodegenerative disease caused by mutations in the α-ß-hydrolase domain-containing 12 gene (ABHD12). Only five homozygous ABHD12 mutations have been reported and the pathogenesis of PHARC remains unclear. We evaluated a woman who manifested short stature as well as the typical features of PHARC. Sequence analysis of ABHD12 revealed a novel heterozygous c.1129A>T (p.Lys377*) mutation. Targeted comparative genomic hybridization detected a 59-kb deletion that encompasses exon 1 of ABHD12 and exons 1-4 of an adjacent gene, GINS1, and includes the promoters of both genes. The heterozygous deletion was also carried by the patient's asymptomatic mother. Quantitative reverse transcription-PCR demonstrated ∼50% decreased expression of ABHD12 RNA in lymphoblastoid cell lines from both individuals. Activity-based protein profiling of serine hydrolases revealed absence of ABHD12 hydrolase activity in the patient and 50% reduction in her mother. This is the first report of compound heterozygosity in PHARC and the first study to describe how a mutation might affect ABHD12 expression and function. The possible involvement of haploinsufficiency for GINS1, a DNA replication complex protein, in the short stature of the patient and her mother requires further studies.

Downregulation of cannabinoid receptor 1 from neuropeptide Y interneurons in the basal ganglia of patients with Huntington's disease and mouse models.

Cannabinoid receptor 1 (CB(1) receptor) controls several neuronal functions, including neurotransmitter release, synaptic plasticity, gene expression and neuronal viability. Downregulation of CB(1) expression in the basal ganglia of patients with Huntington's disease (HD) and animal models represents one of the earliest molecular events induced by mutant huntingtin (mHtt). This early disruption of neuronal CB(1) signaling is thought to contribute to HD symptoms and neurodegeneration. Here we determined whether CB(1) downregulation measured in patients with HD and mouse models was ubiquitous or restricted to specific striatal neuronal subpopulations. Using unbiased semi-quantitative immunohistochemistry, we confirmed previous studies showing that CB(1) expression is downregulated in medium spiny neurons of the indirect pathway, and found that CB(1) is also downregulated in neuropeptide Y (NPY)/neuronal nitric oxide synthase (nNOS)-expressing interneurons while remaining unchanged in parvalbumin- and calretinin-expressing interneurons. CB(1) downregulation in striatal NPY/nNOS-expressing interneurons occurs in R6/2 mice, Hdh(Q150/Q150) mice and the caudate nucleus of patients with HD. In R6/2 mice, CB(1) downregulation in NPY/nNOS-expressing interneurons correlates with diffuse expression of mHtt in the soma. This downregulation also occludes the ability of cannabinoid agonists to activate the pro-survival signaling molecule cAMP response element-binding protein in NPY/nNOS-expressing interneurons. Loss of CB(1) signaling in NPY/nNOS-expressing interneurons could contribute to the impairment of basal ganglia functions linked to HD.

Mitochondrial abnormalities in the putamen in Parkinson's disease dyskinesia.

Prolonged treatment of Parkinson's disease (PD) with levodopa leads to disabling side effects collectively referred to as 'dyskinesias'. We hypothesized that bioenergetic function in the putamen might play a crucial role in the development of dyskinesias. To test this hypothesis, we used post mortem samples of the human putamen and applied real time-PCR approaches and gene expression microarrays. We found that mitochondrial DNA (mtDNA) levels are decreased in patients who have developed dyskinesias, and mtDNA damage is concomitantly increased. These pathologies were not observed in PD subjects without signs of dyskinesias. The group of nuclear mRNA transcripts coding for the proteins of the mitochondrial electron transfer chain was decreased in patients with dyskinesias to a larger extent than in patients who had not developed dyskinesias. To examine whether dopamine fluctuations affect mtDNA levels in dopaminoceptive neurons, rat striatal neurons in culture were repeatedly exposed to levodopa, dopamine or their metabolites. MtDNA levels were reduced after treatment with dopamine, but not after treatment with dopamine metabolites. Levodopa led to an increase in mtDNA levels. We conclude that mitochondrial susceptibility in the putamen plays a role in the development of dyskinesias.

Differences in lymphocyte electron transport gene expression levels between subjects with bipolar disorder and normal controls in response to glucose deprivation stress.

CONTEXT: Bipolar disorder (BPD) is among the top 10 causes of disability worldwide. Recent findings on the etiology of the disease point to a disturbed mitochondrial energy metabolism in the brain of subjects with BPD. OBJECTIVE: To test whether gene transcripts for proteins of the mitochondrial respiratory chain have altered levels in glucose-deprived lymphocytes from patients with BPD. DESIGN: Microarrays were used to measure gene expression levels in fresh lymphocytes and in lymphocytes cultured for 5 days in regular or low-glucose medium. SETTING: Subjects with BPD were recruited through the Schizophrenia and Bipolar Disorders Program, McLean Hospital, Belmont, Mass. Controls were recruited through advertising. Patients A total of 21 patients with BPD (inpatients and outpatients) and 21 control subjects. Main Outcome Measure Expression levels for genes of proteins involved in mitochondrial respiration. RESULTS: We found an opposite molecular response of control and BPD lymphocytes to glucose deprivation. Whereas lymphocytes of normal controls responded to glucose deprivation with an up-regulation of nuclear transcripts for proteins of the electron transfer chain, subjects with BPD had a tendency to down-regulate these transcripts. CONCLUSIONS: The results suggest that the normal molecular adaptation to energy stress is deficient in lymphocytes from patients with BPD.

The cannabinoid-1 receptor is abundantly expressed in striatal striosomes and striosome-dendron bouquets of the substantia nigra.

Presynaptic cannabinoid-1 receptors (CB1-R) bind endogenous and exogenous cannabinoids to modulate neurotransmitter release. CB1-Rs are expressed throughout the basal ganglia, including striatum and substantia nigra, where they play a role in learning and control of motivated actions. However, the pattern of CB1-R expression across different striatal compartments, microcircuits and efferent targets, and the contribution of different CB1-R-expressing neurons to this pattern, are unclear. We use a combination of conventional techniques and novel genetic models to evaluate CB1-R expression in striosome (patch) and matrix compartments of the striatum, and in nigral targets of striatal medium spiny projection neurons (MSNs). CB1-R protein and mRNA follow a descending dorsolateral-to-ventromedial intensity gradient in the caudal striatum, with elevated expression in striosomes relative to the surrounding matrix. The lateral predominance of striosome CB1-Rs contrasts with that of the classical striosomal marker, the mu opioid receptor (MOR), which is expressed most prominently in rostromedial striosomes. The dorsolateral-to-ventromedial CB1-R gradient is similar to Drd2 dopamine receptor immunoreactivity and opposite to Substance P. This topology of CB1-R expression is maintained downstream in the globus pallidus and substantia nigra. Dense CB1-R-expressing striatonigral fibers extend dorsally within the substantia nigra pars reticulata, and colocalize with bundles of ventrally extending, striosome-targeted, dendrites of dopamine-containing neurons in the substantia nigra pars compacta (striosome-dendron bouquets). Within striatum, CB1-Rs colocalize with fluorescently labeled MSN collaterals within the striosomes. Cre recombinase-mediated deletion of CB1-Rs from cortical projection neurons or MSNs, and MSN-selective reintroduction of CB1-Rs in knockout mice, demonstrate that the principal source of CB1-Rs in dorsolateral striosomes is local MSN collaterals. These data suggest a role for CB1-Rs in caudal dorsolateral striosome collaterals and striosome-dendron bouquet projections to lateral substantia nigra, where they are anatomically poised to mediate presynaptic disinhibition of both striosomal MSNs and midbrain dopamine neurons in response to endocannabinoids and cannabinomimetics.

Lithium administration to preadolescent rats causes long-lasting increases in anxiety-like behavior and has molecular consequences.

Lithium (Li) is frequently used in the treatment of bipolar disorder (BPD), a debilitating condition that is increasingly diagnosed in children and adolescents. Because the symptoms of BPD in children are different from the typical symptoms in adulthood and have significant overlap with other childhood psychiatric disorders, this disorder is notoriously difficult to diagnose. This raises the possibility that some children not affected by BPD are treated with Li during key periods of brain development. The objective of this investigation was to examine the long-term effects of Li on the developing brain via a series of behavioral and molecular studies in rats. Rat pups were reared on Li chow for 3 weeks. Parallel groups were tested while on Li chow or 2 and 6 weeks after discontinuation of treatment. We found increased measures of anxiety-like behavior at all times tested. Gene microarray studies of the amygdala revealed that Li affected the expression of gene transcripts of the synapse and the cytoskeleton, suggesting that the treatment induced synaptic adjustments. Our study indicates that Li can alter the trajectory of brain development. Although the effects of Li on the normal brain seems unfavorable, effects on the abnormal brain cannot be determined from these studies alone and may well be therapeutic. Our results indicate that Li administration to the normal brain has the potential for lasting adverse effects.

Altered attention and prefrontal cortex gene expression in rats after binge-like exposure to cocaine during adolescence.

Illicit use of drugs frequently begins and escalates during adolescence, with long-term adverse consequences. Because it is increasingly accepted that neural development continues through adolescence, addiction research has become more invested in understanding the behavioral and molecular consequences of early exposure to drugs of abuse. In a novel binge administration paradigm designed to model the pattern of human adolescent drug use, we administered ascending doses of cocaine or saline during a 12-d developmental period [postnatal day 35 (P35) to P46] corresponding to human adolescence. During adulthood (P70), rats treated with this regimen displayed increased responsiveness to the stimulant effects of cocaine. Adult rats also displayed abnormally rapid shifts in attention when performing an attentional set-shifting task, which measures the ability to shift attention between stimuli and whose performance requires an intact prefrontal cortex (PFC). Treatment with cocaine during adolescence also caused acute alterations in the expression of genes encoding cell adhesion molecules and transcription factors within the PFC. Furthermore, we observed decreases in histone methylation, which may indicate a role for chromatin remodeling in the observed changes in gene expression patterns. These findings suggest that exposure to cocaine during adolescence has far-reaching molecular and behavioral consequences in the rat PFC that develop over time and endure long after drug administration has ceased.

Brain reward regulated by AMPA receptor subunits in nucleus accumbens shell.

Drugs of abuse alter expression of AMPA-type glutamate receptor subunits (GluRs) in the nucleus accumbens (NAc), a key component of brain reward systems. The impact of this regulation on general motivational states is unclear. Here, we used herpes simplex virus vectors to examine how transient increases in the expression of GluR1 or GluR2 protein in the shell component of NAc affect the rewarding impact of electrical stimulation of the medial forebrain bundle, as reflected by intracranial self-stimulation (ICSS) thresholds in rats. We found that elevated GluR1 in NAc shell increases ICSS thresholds, an effect similar to that caused by treatments that cause anhedonia and dysphoria (prodepressive effects) in rats and humans (e.g., drug withdrawal, kappa-opioid agonists). In contrast, elevated GluR2 decreases ICSS thresholds, an effect similar to that caused by rewarding treatments (e.g., drugs of abuse). To confirm that viral vector-mediated elevations of GluR1 in the NAc shell produce molecular consequences that are different from those of elevated GluR2, we examined the expression of a set of drug-regulated genes 3 d after treatment using quantitative PCR. Elevated GluR1 was accompanied by sustained increases in the gene for GluR1, whereas elevated GluR2 was accompanied by decreases in prodynorphin. These data suggest that GluR1 and GluR2 in the NAc shell play opposing roles in the regulation of motivated behavior.

Modulation of Hematopoietic Lineage Specification Impacts TREM2 Expression in Microglia-Like Cells Derived From Human Stem Cells.

Microglia are the primary innate immune cell type in the brain, and their dysfunction has been linked to a variety of central nervous system disorders. Human microglia are extraordinarily difficult to obtain for experimental investigation, limiting our ability to study the impact of human genetic variants on microglia functions. Previous studies have reported that microglia-like cells can be derived from human monocytes or pluripotent stem cells. Here, we describe a reproducible relatively simple method for generating microglia-like cells by first deriving embryoid body mesoderm followed by exposure to microglia relevant cytokines. Our approach is based on recent studies demonstrating that microglia originate from primitive yolk sac mesoderm distinct from peripheral macrophages that arise during definitive hematopoiesis. We hypothesized that functional microglia could be derived from human stem cells by employing BMP-4 mesodermal specification followed by exposure to microglia-relevant cytokines, M-CSF, GM-CSF, IL-34, and TGF-ß. Using immunofluorescence microscopy, flow cytometry, and reverse transcription polymerase chain reaction, we observed cells with microglia morphology expressing a repertoire of markers associated with microglia: Iba1, CX3CR1, CD11b, TREM2, HexB, and P2RY12. These microglia-like cells maintain myeloid functional phenotypes including Aß peptide phagocytosis and induction of pro-inflammatory gene expression in response to lipopolysaccharide stimulation. Addition of small molecules BIO and SB431542, previously demonstrated to drive definitive hematopoiesis, resulted in decreased surface expression of TREM2. Together, these data suggest that mesodermal lineage specification followed by cytokine exposure produces microglia-like cells in vitro from human pluripotent stem cells and that this phenotype can be modulated by factors influencing hematopoietic lineage in vitro.

ST-11: A New Brain-Penetrant Microtubule-Destabilizing Agent with Therapeutic Potential for Glioblastoma Multiforme.

Glioblastoma multiforme is a devastating and intractable type of cancer. Current antineoplastic drugs do not improve the median survival of patients diagnosed with glioblastoma multiforme beyond 14 to 15 months, in part because the blood-brain barrier is generally impermeable to many therapeutic agents. Drugs that target microtubules (MT) have shown remarkable efficacy in a variety of cancers, yet their use as glioblastoma multiforme treatments has also been hindered by the scarcity of brain-penetrant MT-targeting compounds. We have discovered a new alkylindole compound, ST-11, that acts directly on MTs and rapidly attenuates their rate of assembly. Accordingly, ST-11 arrests glioblastoma multiforme cells in prometaphase and triggers apoptosis. In vivo analyses reveal that unlike current antitubulin agents, ST-11 readily crosses the blood-brain barrier. Further investigation in a syngeneic orthotopic mouse model of glioblastoma multiforme shows that ST-11 activates caspase-3 in tumors to reduce tumor volume without overt toxicity. Thus, ST-11 represents the first member of a new class of brain-penetrant antitubulin therapeutic agents. Mol Cancer Ther; 15(9); 2018-29. ©2016 AACR.

Modulation of pilocarpine-induced seizures by cannabinoid receptor 1.

Administration of the muscarinic agonist pilocarpine is commonly used to induce seizures in rodents for the study of epilepsy. Activation of muscarinic receptors has been previously shown to increase the production of endocannabinoids in the brain. Endocannabinoids act at the cannabinoid CB1 receptors to reduce neurotransmitter release and the severity of seizures in several models of epilepsy. In this study, we determined the effect of CB1 receptor activity on the induction in mice of seizures by pilocarpine. We found that decreased activation of the CB1 receptor, either through genetic deletion of the receptor or treatment with a CB1 antagonist, increased pilocarpine seizure severity without modifying seizure-induced cell proliferation and cell death. These results indicate that endocannabinoids act at the CB1 receptor to modulate the severity of pilocarpine-induced seizures. Administration of a CB1 agonist produced characteristic CB1-dependent behavioral responses, but did not affect pilocarpine seizure severity. A possible explanation for the lack of effect of CB1 agonist administration on pilocarpine seizures, despite the effects of CB1 antagonist administration and CB1 gene deletion, is that muscarinic receptor-stimulated endocannabinoid production is acting maximally at CB1 receptors to modulate sensitivity to pilocarpine seizures.

ABHD6 blockade exerts antiepileptic activity in PTZ-induced seizures and in spontaneous seizures in R6/2 mice.

The serine hydrolase α/ß-hydrolase domain 6 (ABHD6) hydrolyzes the most abundant endocannabinoid (eCB) in the brain, 2-arachidonoylglycerol (2-AG), and controls its availability at cannabinoid receptors. We show that ABHD6 inhibition decreases pentylenetetrazole (PTZ)-induced generalized tonic-clonic and myoclonic seizure incidence and severity. This effect is retained in Cnr1(-/-) or Cnr2(-/-) mice, but blocked by addition of a subconvulsive dose of picrotoxin, suggesting the involvement of GABAA receptors. ABHD6 inhibition also blocked spontaneous seizures in R6/2 mice, a genetic model of juvenile Huntington's disease known to exhibit dysregulated eCB signaling. ABHD6 blockade retained its antiepileptic activity over chronic dosing and was not associated with psychomotor or cognitive effects. While the etiology of seizures in R6/2 mice remains unsolved, involvement of the hippocampus is suggested by interictal epileptic discharges, increased expression of vGLUT1 but not vGAT, and reduced Neuropeptide Y (NPY) expression. We conclude that ABHD6 inhibition may represent a novel antiepileptic strategy.

Binge cocaine administration in adolescent rats affects amygdalar gene expression patterns and alters anxiety-related behavior in adulthood.

BACKGROUND: Administration of cocaine during adolescence alters neurotransmission and behavioral sensitization in adulthood, but the effect on the acquisition of fear memories and the development of emotion-based neuronal circuits is unknown. METHODS: We examined fear learning and anxiety-related behaviors in adult male rats that were subjected to binge cocaine treatment during adolescence. We furthermore conducted gene expression analyses of the amygdala 22 hours after the last cocaine injection to identify molecular patterns that might lead to altered emotional processing. RESULTS: Rats injected with cocaine during adolescence displayed less anxiety in adulthood than their vehicle-injected counterparts. In addition, cocaine-exposed animals were deficient in their ability to develop contextual fear responses. Cocaine administration caused transient gene expression changes in the Wnt signaling pathway, of axon guidance molecules, and of synaptic proteins, suggesting that cocaine perturbs dendritic structures and synapses in the amygdala. Phosphorylation of glycogen synthase kinase 3 beta, a kinase in the Wnt signaling pathway, was altered immediately following the binge cocaine paradigm and returned to normal levels 22 hours after the last cocaine injection. CONCLUSIONS: Cocaine exposure during adolescence leads to molecular changes in the amygdala and decreases fear learning and anxiety in adulthood.

Downregulation of oligodendrocyte transcripts is associated with impaired prefrontal cortex function in rats.

Abnormalities of brain white matter and oligodendroglia are among the most consistent findings in schizophrenia (Sz) research. Various gene expression microarray studies of post-mortem Sz brains showed a downregulation of myelin transcripts, while imaging and microscopy studies demonstrated decreases in prefrontal cortical (PFC) white matter volume and oligodendroglia density. Currently, the extent to which reduced oligodendrocyte markers contribute to pathophysiological domains of Sz is unknown. We exposed adolescent rats to cuprizone (CPZ), a copper chelator known to cause demyelination in mice, and examined expression of oligodendrocyte mRNA transcripts and PFC-mediated behavior. Rats on the CPZ diet showed decreased expression of mRNA transcripts encoding oligodendroglial proteins within the medial PFC, but not in the hippocampus or the striatum. These rats also displayed a specific deficit in the ability to shift between perceptual dimensions in the attentional set-shifting task, a PFC-mediated behavioral paradigm modeled after the Wisconsin Card Sorting Test (WCST). The inability to shift strategies corresponds to the deficits exhibited by Sz patients in the WCST. The results demonstrate that a reduction in oligodendrocyte markers is associated with impaired PFC-mediated behaviors. Thus, CPZ exposure of rats can serve as a model to examine the contribution of oligodendrocyte perturbation to cognitive deficits observed in Sz.

Decrease in creatine kinase messenger RNA expression in the hippocampus and dorsolateral prefrontal cortex in bipolar disorder.

OBJECTIVES: Bipolar disorder (BPD) affects more than 2 million adults in the USA and ranks among the top 10 causes of worldwide disabilities. Despite its prevalence, very little is known about the etiology of BPD. Recent evidence suggests that cellular energy metabolism is disturbed in BPD. Mitochondrial function is altered, and levels of high-energy phosphates, such as phosphocreatine (PCr), are reduced in the brain. This evidence has led to the hypothesis that deficiencies in energy metabolism could account for some of the pathophysiology observed in BPD. To further explore this hypothesis, we examined levels of creatine kinase (CK) mRNA, the enzyme involved in synthesis and metabolism of PCr, in the hippocampus (HIP) and dorsolateral prefrontal cortex (DLPFC) of control, BPD and schizophrenia subjects. METHODS: Tissue was obtained from the Harvard Brain Tissue Resource Center. Real-time quantitative polymerase chain reaction (HIP, DLPFC) and gene expression microarrays (HIP) were employed to compare the brain and mitochondrial 1 isoforms of CK. RESULTS: Both CK isoforms were downregulated in BPD. Furthermore, mRNA transcripts for oligodendrocyte-specific proteins were downregulated in the DLPFC, whereas the mRNA for the neuron-specific protein microtubule-associated protein 2 was downregulated in the HIP. CONCLUSION: Although some of the downregulation of CK might be explained by cell loss, a more general mechanism seems to be responsible. The downregulation of CK transcripts, if translated into protein levels, could explain the reduction of high-energy phosphates previously observed in BPD.