Adam I. Kaplin

IL-6 induces regionally selective spinal cord injury in patients with the neuroinflammatory disorder transverse myelitis

Transverse myelitis (TM) is an immune-mediated spinal cord disorder associated with inflammation, demyelination, and axonal damage. We investigated the soluble immune derangements present in TM patients and found that IL-6 levels were selectively and dramatically elevated in the cerebrospinal fluid and directly correlated with markers of tissue injury and sustained clinical disability. IL-6 was necessary and sufficient to mediate cellular injury in spinal cord organotypic tissue culture sections through activation of the JAK/STAT pathway, resulting in increased activity of iNOS and poly(ADP-ribose) polymerase (PARP). Rats intrathecally infused with IL-6 developed progressive weakness and spinal cord inflammation, demyelination, and axonal damage, which were blocked by PARP inhibition. Addition of IL-6 to brain organotypic cultures or into the cerebral ventricles of adult rats did not activate the JAK/STAT pathway, which is potentially due to increased expression of soluble IL-6 receptor in the brain relative to the spinal cord that may antagonize IL-6 signaling in this context. The spatially distinct responses to IL-6 may underlie regional vulnerability of different parts of the CNS to inflammatory injury. The elucidation of this pathway identifies specific therapeutic targets in the management of CNS autoimmune conditions.

Diagnosis and management of acute myelopathies

Background:Acute myelopathies represent a heterogeneous group of disorders with distinct etiologies, clinical and radiologic features, and prognoses. Transverse myelitis (TM) is a prototype member of this group in which an immune-mediated process causes neural injury to the spinal cord, resulting in varying degrees of weakness, sensory alterations, and autonomic dysfunction. TM may exist as part of a multifocal CNS disease (eg, MS), multisystemic disease (eg, systemic lupus erythematosus), or as an isolated, idiopathic entity. Review Summary:In this article, we summarize recent classification and diagnostic schemes, which provide a framework for the diagnosis and management of patients with acute myelopathy. Additionally, we review the state of current knowledge about the epidemiology, natural history, immunopathogenesis, and treatment strategies for patients with TM. Conclusions:Our understanding of the classification, diagnosis, pathogenesis, and treatment of TM has recently begun to expand dramatically. With more rigorous criteria applied to distinguish acute myelopathies and with an emerging understanding of immunopathogenic events that underlie TM, it may now be possible to effectively initiate treatments in many of these disorders. Through the investigation of TM, we are also gaining a broader appreciation of the mechanisms that lead to autoimmune neurologic diseases in general.

Protein traffic between distinct plasma membrane domains: Isolation and characterization of vesicular carriers involved in transcytosis

We have isolated a population of vesicular carriers involved in the transport (transcytosis) of proteins from the basolateral to the apical plasma membrane of hepatocytes. The obtained fraction was enriched in compartments containing known transcytosed proteins and depleted in elements of the secretory pathway, Golgi elements, basolateral plasma membrane, as well as early endosomal components. The fraction was analyzed by biochemical and immunological procedures. Antibodies raised against the proteins in the fraction recognized a single 108K antigen. Based on its subcellular distribution, the 108K antigen may represent a novel marker for transcytotic vesicular carriers.

IDIOPATHIC TRANSVERSE MYELITIS: CORTICOSTEROIDS, PLASMA EXCHANGE, OR CYCLOPHOSPHAMIDE

Transverse myelitis is a focal disorder of the spinal cord in which an immune-mediated process results in neural injury. In this large retrospective study, we compare patients who received one of four treatments to identify the most effective therapies. We identified subsets of patients who received clinical benefit from plasma exchange or cyclophosphamide being included in their treatment regimen.

Interleukin-17 in transverse myelitis and multiple sclerosis

CSF IL-6 is elevated in transverse myelitis (TM) and predicts disability. Since IL-17 regulates cytokines (TNFalpha, IL-1beta and IL-6) known to stimulate IL-6 production by astrocytes, we sought to determine whether IL-17 was increased in TM and MS compared to healthy controls (HC) and other neurologic diseases (OND). IL-17 and IL-6 levels were measured in stimulated peripheral blood mononuclear cell (PBMC) supernatants from HC, MS, TM and OND. IL-17 was increased in TM compared to HC, MS, and OND (mean pg/ml+/-standard error; HC: 36.1+/-11.7, MS: 89.4+/-23.3, TM: 302.6+/-152.5, OND: 41.2+/-13.0, p=0.01). IL-6 was increased in TM relative to MS and HC (HC: 2624 pg/ml+/-641, MS: 6129+/-982, TM: 12,536+/-2657, OND: 6920+/-1801, p<0.002). MS patients with early disease (<2 years) also had increased levels of IL-17 (p<0.04) and IL-6 (p<0.05). Cytokine neutralization experiments demonstrated that IL-6 was the main inducer of astrocyte IL-6 production. We conclude that IL-17 and IL-6 production from PBMC in TM and early MS are increased and induce astrocyte IL-6 production through IL-6.

Reduction of Disease Activity and Disability With High-Dose Cyclophosphamide in Patients With Aggressive Multiple Sclerosis

OBJECTIVE To explore the safety and effectiveness of high-dose cyclophosphamide (HiCy) without bone marrow transplantation in patients with aggressive multiple sclerosis (MS). DESIGN A 2-year open-label trial of patients with aggressive relapsing-remitting multiple sclerosis (RRMS) given an immunoablative regimen of HiCy (50 mg/kg/d for 4 consecutive days) with no subsequent immunomodulatory therapy unless disease activity reappeared that required rescue therapy. SETTING The Johns Hopkins University Multiple Sclerosis Center, Baltimore, Maryland. Patients A total of 21 patients with RRMS were screened for eligibility and 9 patients were enrolled in the trial. Patients were required to have 2 or more gadolinium-enhancing lesions on each of 2 pretreatment magnetic resonance imaging scans, at least 1 clinical exacerbation in the 12 months prior to HiCy treatment, or a sustained increase of 1.0 point or higher on the Expanded Disability Status Scale (EDSS) in the preceding year. Intervention Patients received 50 mg/kg/d of cyclophosphamide intravenously for 4 consecutive days, followed by 5 mug/kg/d of granulocyte colony-stimulating factor 6 days after completion of HiCy treatment, until the absolute neutrophil count exceeded 1.0 x 10(9) cells/L for 2 consecutive days. MAIN OUTCOME MEASURES The primary outcome of the study was the safety and tolerability of HiCy in patients with RRMS. Secondary outcome measures included a change in gadolinium-enhancing lesions on magnetic resonance images and a change in disability measures (EDSS and Multiple Sclerosis Functional Composite). RESULTS Nine patients were treated and followed up for a mean period of 23 months. Eight patients had failed conventional therapy and 1 was treatment naive. The median age at time of entry was 29 years (range, 20-47 years). All patients developed transient total or near-total pancytopenia as expected, followed by hematopoietic recovery in 10 to 17 days, stimulated by granulocyte colony-stimulating factor. There were no deaths or unexpected serious adverse events. There was a statistically significant reduction in disability (EDSS) at follow-up (mean [SD] decrease, 2.11 [1.97]; 39.4%; P = .02). The mean (SD) number of gadolinium-enhancing lesions on the 2 pretreatment scans were 6.5 (2.1) and 1.2 (2.3) at follow-up (81.4% reduction; P = .01). Two patients required rescue treatment with other immunomodulatory therapies during the study owing to MS exacerbations. CONCLUSION Treatment with HiCy was safe and well tolerated in our patients with MS. Patients experienced a pronounced reduction in disease activity and disability after HiCy treatment. This immunoablative regimen of cyclophosphamide for patients with aggressive MS is worthy of further study and may be an alternative to bone marrow transplantation. Published online June 9, 2008 (doi:10.1001/archneurol.65.8.noc80042).

Unkind cytokines: Current evidence for the potential role of cytokines in immune-mediated depression

A great deal of interest has recently become focused on interactions between the nervous and the immune systems, including the potential for alterations in immune function to contribute to various psychiatric and neurologic disorders. Evidence suggests that cytokines may be involved in the development of depression. Immune-mediated mechanisms in the pathophysiology of some types of depression are reviewed from both clinical and animal studies and the difficulties inherent in studying the interplay of these two complex systems in the development of depression are described.

Glutamate in CNS Neurodegeneration and Cognition and its Regulation by GCPII Inhibition

Glutamate, first identified in 1866, is the primary excitatory neurotransmitter in the brain. While it is critically important in many highly regulated cortical functions such as learning and memory, glutamate can be much like the magic the Sorcerers Apprentice used in Goethes poem: when conjured under unregulated conditions glutamate can get quickly out of control and lead to deleterious consequences. Two broad types of glutamate receptors, the ionotropic and metabotropic, facilitate glutamatergic neurotransmission in the CNS and play key roles in regulating cognitive function. Excessive activation of these receptors leads to excitotoxicity, especially in brain regions that are developmentally and regionally vulnerable to this kind of injury. Dysregulation of glutamate signaling leads to neurodegeneration that plays a role in a number of neuropsychiatric diseases, prompting the development and utilization of novel strategies to balance the beneficial and deleterious potential of this important neurotransmitter. Inhibition of the enzyme glutamate carboxypeptidase II (GCPII) is one method of manipulating glutamate neurotransmission. Positive outcomes (decreased neuronal loss, improved cognition) have been demonstrated in preclinical models of ALS, stroke, and Multiple Sclerosis due to inhibition of GCPII, suggesting this method of glutamate regulation could serve as a therapeutic means for treating neurodegeneration and cognitive impairment.

Inhibition of Glutamate Carboxypeptidase II (GCPII) activity as a treatment for cognitive impairment in multiple sclerosis

Half of all patients with multiple sclerosis (MS) experience cognitive impairment, for which there is no pharmacological treatment. Using magnetic resonance spectroscopy (MRS), we examined metabolic changes in the hippocampi of MS patients, compared the findings to performance on a neurocognitive test battery, and found that N-acetylaspartylglutamate (NAAG) concentration correlated with cognitive functioning. Specifically, MS patients with cognitive impairment had low hippocampal NAAG levels, whereas those with normal cognition demonstrated higher levels. We then evaluated glutamate carboxypeptidase II (GCPII) inhibitors, known to increase brain NAAG levels, on cognition in the experimental autoimmune encephalomyelitis (EAE) model of MS. Whereas GCPII inhibitor administration did not affect physical disabilities, it increased brain NAAG levels and dramatically improved learning and memory test performance compared with vehicle-treated EAE mice. These data suggest that NAAG is a unique biomarker for cognitive function in MS and that inhibition of GCPII might be a unique therapeutic strategy for recovery of cognitive function.

Imaging Serotonergic Transmission with [11C]DASB-PET in Depressed and Non-Depressed Patients Infected with HIV

INTRODUCTION Site-selective imaging can provide significant insight into the mechanism of HIV-associated neurological disease. The goal of this study was to evaluate the involvement of serotonergic transmission in HIV-associated depression using [(11)C]DASB, a serotonin transporter (5-HTT)-specific radiopharmaceutical for positron emission tomography (PET). METHODS Nine depressed HIV+ subjects (HIV-D), 9 non-depressed HIV+ subjects (HIV-ND) and 7 healthy controls (HC) underwent an MRI scan and a [(11)C]DASB-PET scan. The outcome measure was 5-HTT binding potential normalized to non-displaceable tissue radioligand (BP(ND)). RESULTS HIV-ND subjects had lower mean regional 5-HTT BP(ND) estimates across regions compared to HC, while HIV-D subjects demonstrated higher mean regional binding values than HIV-ND subjects in most regions. Prior to correction for the false discovery rate, HIV-ND had significantly lower BP(ND) values compared to HC subjects in two regions (insula and anterior cingulate) and all HIV+ patients had significantly lower binding than HC in all regions except for the midbrain, thalamus and pons. After correction for the false discovery rate, only the insula showed significantly lower binding in HIV+ subjects compared to HC (P<0.0045). Despite a significant difference in the duration of illness between the HIV-D and HIV-ND groups, there was no definite correlation between the duration of illness and BP(ND). CONCLUSION Lower [(11)C]DASB binding in HIV+ patients compared to HC may reflect serotonergic neuronal loss as a component of generalized HIV-associated neurodegeneration. Higher mean regional BP(ND) values in HIV-D compared to HIV-ND subjects could reflect increased density of 5-HTT, leading to increased clearance of serotonin from the synapse, which could account, in part, for symptoms of depression. The lack of correlation between duration of illness and binding argues against these findings being the result of differential neurodegeneration only. Our findings suggest a possible role for dysregulated serotonergic transmission in HIV-associated depression.