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In multiple sclerosis, cerebellar symptoms are associated with clinical impairment and an increased likelihood of progressive course. Cortical atrophy and synaptic dysfunction play a prominent role in cerebellar pathology and although the dentate nucleus is a predilection site for lesion development, structural synaptic changes in this region remain largely unexplored. Moreover, the mechanisms leading to synaptic dysfunction have not yet been investigated at an ultrastructural level in multiple sclerosis. Here, we report on synaptic changes of dentate nuclei in post-mortem cerebella of 16 multiple sclerosis patients and eight controls at the histological level as well as an electron microscopy evaluation of afferent synapses of the cerebellar dentate and pontine nuclei of one multiple sclerosis patient and one control. We found a significant reduction of afferent dentate synapses in multiple sclerosis, irrespective of the presence of demyelination, and a close relationship between glial processes and dentate synapses. Ultrastructurally, we show autophagosomes containing degradation products of synaptic vesicles within dendrites, residual bodies within intact-appearing axons and free postsynaptic densities opposed to astrocytic appendages. Our study demonstrates loss of dentate afferent synapses and provides, for the first time, ultrastructural evidence pointing towards neuron-autonomous and neuroglia-mediated mechanisms of synaptic degradation in chronic multiple sclerosis., (© 2016 International Society of Neuropathology.)

Aims: In Wilson disease (WD), T2/T2*-weighted (T2*w) MRI frequently shows hypointensity in the basal ganglia that is suggestive of paramagnetic deposits. It is currently unknown whether this hypointensity is related to copper or iron deposition. We examined the neuropathological correlates of this MRI pattern, particularly in relation to iron and copper concentrations., Methods: Brain slices from nine WD and six control cases were investigated using a 7T-MRI system. High-resolution T2*w images were acquired and R2* parametric maps were reconstructed using a multigradient recalled echo sequence. R2* was measured in the globus pallidus (GP) and the putamen. Corresponding histopathological sections containing the lentiform nucleus were examined using Turnbull iron staining, and double staining combining Turnbull with immunohistochemistry for macrophages or astrocytes. Quantitative densitometry of the iron staining as well as copper and iron concentrations were measured in the GP and putamen and correlated with R2* values., Results: T2*w hypointensity in the GP and/or putamen was apparent in WD cases and R2* values correlated with quantitative densitometry of iron staining. In WD, iron and copper concentrations were increased in the putamen compared to controls. R2* was correlated with the iron concentration in the GP and putamen, whereas no correlation was observed for the copper concentration. Patients with more pronounced pathological severity in the putamen displayed increased iron concentration, which correlated with an elevated number of iron-containing macrophages., Conclusions: T2/T2*w hypointensity observed in vivo in the basal ganglia of WD patients is related to iron rather than copper deposits., (© 2016 British Neuropathological Society.)

Objectives: The etiology and genetic susceptibility of primary central nervous system vasculitis (PCNSV) are still unclear., Patients and Methods: We analyzed the DNA of 25 Caucasian patients with PCNSV for human leucocyte antigen genes HLA-A, HLA-B, HLA-DRB1, and HLA-DQB1, respectively. HLA-frequencies of the 25 patients with PCNSV were compared with HLA-frequencies of matched Caucasian controls., Results: No statistically significant associations were found for HLA-B, HLA-DR1 and HLA-DQB1 variant. In the PCNSV group, only the HLA-A*69 variant was found more often than expected statistically., Conclusion: The results of this study indicate a potential association of HLA marker with PCNSV in Caucasian patients. Further studies are needed to elucidate the role of genes within the human major histocompatibility complex in the pathogenesis of this angiopathy., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: The diagnosis of multiple sclerosis (MS) is currently based solely on clinical and magnetic resonance imaging features. However, histopathological studies have revealed four different patterns of lesion pathology in patients diagnosed with MS, suggesting that MS may be a pathologically heterogeneous syndrome rather than a single disease entity., Objective: The aim of this study was to investigate whether patients with pattern I MS differ from patients with pattern II or III MS with regard to cerebrospinal fluid (CSF) findings, especially with reference to intrathecal IgG synthesis, which is found in most patients with MS but is frequently missing in MS mimics such as aquaporin-4-IgG-positive neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein-IgG-positive encephalomyelitis., Methods: Findings from 68 lumbar punctures in patients who underwent brain biopsy as part of their diagnostic work-up and who could be unequivocally classified as having pattern I, pattern II or pattern III MS were analysed retrospectively., Results: Oligoclonal bands (OCBs) were present in 88.2% of samples from pattern I MS patients but in only 27% of samples from patients with pattern II or pattern III MS (P < 0.00004); moreover, OCBs were present only transiently in some of the latter patients. A polyspecific intrathecal IgG response to measles, rubella and/or varicella zoster virus (so-called MRZ reaction) was previously reported in 60-80% of MS patients, but was absent in all pattern II or III MS patients tested (P < 0.00001 vs. previous cohorts). In contrast, the albumin CSF/serum ratio (QAlb), a marker of blood-CSF barrier function, was more frequently elevated in samples from pattern II and III MS patients (P < 0.002). Accordingly, QAlb values and albumin and total protein levels were higher in pattern II and III MS samples than in pattern I MS samples (P < 0.005, P < 0.009 and P < 0.006, respectively)., Conclusions: Patients with pattern II or pattern III MS differ significantly from patients with pattern I MS as well as from previous, histologically non-classified MS cohorts with regard to both intrathecal IgG synthesis and blood-CSF barrier function. Our findings strongly corroborate the notion that pattern II and pattern III MS are entities distinct from pattern I MS.

Remyelination is in the center of new therapies for the treatment of multiple sclerosis to resolve and improve disease symptoms and protect axons from further damage. Although remyelination is considered beneficial in the long term, it is not known, whether this is also the case early in lesion formation. Additionally, the precise timing of acute axonal damage and remyelination has not been assessed so far. To shed light onto the interrelation between axons and the myelin sheath during de- and remyelination, we employed cuprizone- and focal lysolecithin-induced demyelination and performed time course experiments assessing the evolution of early and late stage remyelination and axonal damage. We observed damaged axons with signs of remyelination after cuprizone diet cessation and lysolecithin injection. Similar observations were made in early multiple sclerosis lesions. To assess the correlation of remyelination and axonal damage in multiple sclerosis lesions, we took advantage of a cohort of patients with early and late stage remyelinated lesions and assessed the number of APP- and SMI32- positive damaged axons and the density of SMI31-positive and silver impregnated preserved axons. Early de- and remyelinating lesions did not differ with respect to axonal density and axonal damage, but we observed a lower axonal density in late stage demyelinated multiple sclerosis lesions than in remyelinated multiple sclerosis lesions. Our findings suggest that remyelination may not only be protective over a long period of time, but may play an important role in the immediate axonal recuperation after a demyelinating insult., (© 2017 The Authors GLIA Published by Wiley Periodicals, Inc.)

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) in which oligodendrocytes, the CNS cells that stain most robustly for iron and myelin are the targets of injury. Metals are essential for normal CNS functioning, and metal imbalances have been linked to demyelination and neurodegeneration. Using a multidisciplinary approach involving synchrotron techniques, iron histochemistry and immunohistochemistry, we compared the distribution and quantification of iron and zinc in MS lesions to the surrounding normal appearing and periplaque white matter, and assessed the involvement of these metals in MS lesion pathogenesis. We found that the distribution of iron and zinc is heterogeneous in MS plaques, and with few remarkable exceptions they do not accumulate in chronic MS lesions. We show that brain iron tends to decrease with increasing age and disease duration of MS patients; reactive astrocytes organized in large astrogliotic areas in a subset of smoldering and inactive plaques accumulate iron and safely store it in ferritin; a subset of smoldering lesions do not contain a rim of iron-loaded macrophages/microglia; and the iron content of shadow plaques varies with the stage of remyelination. Zinc in MS lesions was generally decreased, paralleling myelin loss. Iron accumulates concentrically in a subset of chronic inactive lesions suggesting that not all iron rims around MS lesions equate with smoldering plaques. Upon degeneration of iron-loaded microglia/macrophages, astrocytes may form an additional protective barrier that may prevent iron-induced oxidative damage.

Microglia as principle innate immune cells of the central nervous system (CNS) are the first line of defense against invading pathogens. They are capable of sensing infections through diverse receptors, such as Toll-like receptor 4 (TLR4). This receptor is best known for its ability to recognize bacterial lipopolysaccharide (LPS), a causative agent of gram-negative sepsis and septic shock. A putative, naturally occurring antagonist of TLR4 derives from the photosynthetic bacterium Rhodobacter sphaeroides. However, the antagonistic potential of R. sphaeroides LPS (Rs-LPS) is no universal feature, since several studies suggested agonistic rather than antagonistic actions of this molecule depending on the investigated mammalian species. Here we show the agonistic versus antagonistic potential of Rs-LPS in primary mouse microglia. We demonstrate that Rs-LPS efficiently induces the release of cytokines and chemokines, which depends on TLR4, MyD88, and TRIF, but not CD14. Furthermore, Rs-LPS is able to regulate the phagocytic capacity of microglia as agonist, while it antagonizes Re-LPS-induced MHC I expression. Finally, to our knowledge, we are the first to provide in vivo evidence for an agonistic potential of Rs-LPS, as it efficiently triggers the recruitment of peripheral immune cells to the endotoxin-challenged CNS. Together, our results argue for a versatile and complex organization of the microglial TLR4 system, which specifically translates exogenous signals into cellular functions. Importantly, as demonstrated here for microglia, the antagonistic potential of Rs-LPS needs to be considered with caution, as reactions to Rs-LPS not only differ by cell type, but even by function within one cell type., (© 2017 Wiley Periodicals, Inc.)

Cortical demyelination is a widely recognized hallmark of multiple sclerosis (MS) and correlate of disease progression and cognitive decline. The pathomechanisms initiating and driving gray matter damage are only incompletely understood. Here, we determined the infiltrating leukocyte subpopulations in 26 cortical demyelinated lesions of biopsied MS patients and assessed their contribution to cortical lesion formation in a newly developed mouse model. We find that conformation-specific anti-myelin antibodies contribute to cortical demyelination even in the absence of the classical complement pathway. T cells and natural killer cells are relevant for intracortical type 2 but dispensable for subpial type 3 lesions, whereas CCR2 + monocytes are required for both. Depleting CCR2 + monocytes in marmoset monkeys with experimental autoimmune encephalomyelitis using a novel humanized CCR2 targeting antibody translates into significantly less cortical demyelination and disease severity. We conclude that biologics depleting CCR2 + monocytes might be attractive candidates for preventing cortical lesion formation and ameliorating disease progression in MS.

Background: Co-occurrence of multiple sclerosis (MS) and glial tumours (GT) is uncommon although occasionally reported in medical literature. Interpreting the overlapping radiologic and clinical characteristics of glial tumours, MS lesions, and progressive multifocal leukoencephalopathy (PML) can be a significant diagnostic challenge., Case Presentation: We report a case of anaplastic astrocytoma mimicking PML in a 27-year-old patient with a 15-year history of MS. She was treated with interferon, natalizumab and finally fingolimod due to active MS. Follow-up MRI, blood and cerebrospinal fluid examinations, and biopsy were conducted, but only the latter was able to reveal the cause of progressive worsening of patient's disease., Conclusions: Anaplastic astrocytoma misdiagnosed as PML has not yet been described. We suppose that the astrocytoma could have evolved from a low grade glioma to anaplastic astrocytoma over time, as the tumour developed adjacent to typical MS plaques. The role of the immunomodulatory treatment as well as other immunological factors in the malignant transformation can only be hypothesised. We discuss clinical, laboratory and diagnostic aspects of a malignant GT, MS lesions and PML. The diagnosis of malignant GT must be kept in mind when an atypical lesion develops in a patient with MS.

Objectives: To compare clinical features and outcome, imaging characteristics, biopsy results and laboratory findings in a cohort of 69 patients with suspected or diagnosed primary central nervous system vasculitis (PCNSV) in adults; to identify risk factors and predictive features for PCNSV., Patients and Methods: We performed a case-control-study including 69 patients referred with suspected PCNSV from whom 25 were confirmed by predetermined diagnostic criteria based on biopsy (72%) or angiography (28%). Forty-four patients turned out to have 15 distinct other diagnoses. Clinical and diagnostic data were compared between PCNSV and Non-PCNSV cohorts., Results: Clinical presentation was not able to discriminate between PCNSV and its differential diagnoses. However, a worse clinical outcome was associated with PCNSV (p=0.005). Biopsy (p=0.004), contrast enhancement (p=0.000) or tumour-like mass lesion (p=0.008) in magnetic resonance imaging (MRI), intrathecal IgG increase (p=0.020), normal Duplex findings of cerebral arteries (p=0.022) and conventional angiography (p 0.010) were able to distinguish between the two cohorts., Conclusion: In a cohort of 69 patients with suspected PCNSV, a large number (64%) was misdiagnosed and partly received treatment, since mimicking diseases are very difficult to discriminate. Clinical presentation at manifestation does not help to differentiate PCNSV from its mimicking diseases. MRI and cerebrospinal fluid analysis are unlikely to be normal in PCNSV, though unspecific if pathological. Cerebral angiography and biopsy must complement other diagnostics when establishing the diagnosis in order to avoid misdiagnosis and mistreatment., Clinical Trial Registration: German clinical trials register: http://drks-neu.uniklinik-freiburg.de/drks&#95;web/, Unique identifier: DRKS00005347., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Multiple sclerosis is a chronic inflammatory disease of the central nervous system, characterized by demyelination and axonal damage as well as neuronal degeneration. Since oxygen-derived free radicals are an important factor leading to tissue damage in inflammatory multiple sclerosis (MS) lesions, research on antioxidative systems is essential to identify endogenous factors which can possibly counteract oxidative damage. As an important scavenging enzyme family, peroxiredoxins (PRDXs) play a crucial role in preventing oxidative damage; however little is known about their expression and function in MS lesions. In the present study we examined the expression of PRDX2 in white matter lesions of MS patients with long-standing, chronic disease. PRDX2 expression was investigated by immunohistochemistry in the context of oxidative stress and inflammation (determined by microglia/macrophage and T cell infiltration) in ten MS autopsy cases as well as seven control autopsy cases. PRDX2 was found to be upregulated in white matter MS lesions mainly in astrocytes, and its expression level was positively correlated with the degree of inflammation and oxidative stress. Our data suggest that PRDX2 expression contributes to the resistance of astrocytes against oxidative damage.

Background: Axonal damage and loss substantially contribute to the incremental accumulation of clinical disability in progressive multiple sclerosis. Here, we assessed the amount of Wallerian degeneration in brain tissue of multiple sclerosis patients in relation to demyelinating lesion activity and asked whether a transient blockade of Wallerian degeneration decreases axonal loss and clinical disability in a mouse model of inflammatory demyelination., Methods: Wallerian degeneration and acute axonal damage were determined immunohistochemically in the periplaque white matter of multiple sclerosis patients with early actively demyelinating lesions, chronic active lesions, and inactive lesions. Furthermore, we studied the effects of Wallerian degeneration blockage on clinical severity, inflammatory pathology, acute axonal damage, and long-term axonal loss in experimental autoimmune encephalomyelitis using Wallerian degeneration slow (Wld S ) mutant mice., Results: The highest numbers of axons undergoing Wallerian degeneration were found in the perilesional white matter of multiple sclerosis patients early in the disease course and with actively demyelinating lesions. Furthermore, Wallerian degeneration was more abundant in patients harboring chronic active as compared to chronic inactive lesions. No co-localization of neuropeptide Y-Y1 receptor, a bona fide immunohistochemical marker of Wallerian degeneration, with amyloid precursor protein, frequently used as an indicator of acute axonal transport disturbance, was observed in human and mouse tissue, indicating distinct axon-degenerative processes. Experimentally, a delay of Wallerian degeneration, as observed in Wld S mice, did not result in a reduction of clinical disability or acute axonal damage in experimental autoimmune encephalomyelitis, further supporting that acute axonal damage as reflected by axonal transport disturbances does not share common molecular mechanisms with Wallerian degeneration. Furthermore, delaying Wallerian degeneration did not result in a net rescue of axons in late lesion stages of experimental autoimmune encephalomyelitis., Conclusions: Our data indicate that in multiple sclerosis, ongoing demyelination in focal lesions is associated with axonal degeneration in the perilesional white matter, supporting a role for focal pathology in diffuse white matter damage. Also, our results suggest that interfering with Wallerian degeneration in inflammatory demyelination does not suffice to prevent acute axonal damage and finally axonal loss.

Introduction: During the last two decades, septic encephalopathy (SE) was recognized as a clinically relevant problem with a high prevalence in patients at admission and during their hospital stay. SE is a condition associated with increased mortality and morbidity such as long-term cognitive impairment. Areas covered: This review illustrates the pathophysiology of sepsis-associated encephalopathy and encephalitis involving blood-brain-barrier dysfunction and neuroinflammation caused by endothelial and microglial activation by endogenous or pathogen-derived compounds, hypoxia by impaired microvascular regulation and septic shock as well as imbalance of neurotransmitters. The continuum between septic-embolic and septic-metastatic encephalitis and SE is underlined by histological findings. The options of technical examinations and biomarkers to diagnose SE are discussed together with established therapeutic options as well as current experimental approaches. Expert commentary: An outlook for clinicians is provided including promising diagnostic approaches by means of new imaging techniques. Clinical trials with drugs already established for other indications such as statins, erythropoietin and minocycline are warranted in the future.

Background: Severe rebound multiple sclerosis (MS) activity is a life-threatening complication of natalizumab (NTZ) withdrawal, for which pathogenesis and treatment are still unclear. We report the immunological and pathological characterization of a case of central nervous system (CNS) inflammatory demyelination after NTZ discontinuation., Objective: To understand the pathophysiology of this neuroinflammatory condition., Methods: Antemortem blood and cerebrospinal fluid (CSF) analysis was compared with postmortem pathological studies, as well as with novel flow cytometry characterization of immune cells isolated from the CNS parenchyma., Results: Pathological analysis of the brain revealed the presence of innumerable active inflammatory demyelinating lesions typical of immunopathological pattern II. Monocytes/macrophages and B cells were enriched in the CNS parenchyma compared to the CSF. Numerous plasma cells were present in the lesions, but CD8 T lymphocytes were predominant in the parenchyma, as opposed to CD4 in the CSF. CNS-infiltrating lymphocytes expressed high levels of adhesion molecules, granzyme B (GzB), interferon-gamma (IFN-γ), and interleukin (IL)-17., Conclusions: Our results underline the differences in immune cell populations between the CSF and the CNS parenchyma, and suggest that aggressive immunosuppressive therapy targeting both T and B lymphocytes is warranted to control the overwhelming CNS inflammation.

Purpose: The aim of this study was to investigate whether intraoperative ultrasonography (IOUS) helped the surgeon navigate towards the tumor as seen in preoperative magnetic resonance imaging and whether IOUS was able to distinguish between tumor margins and the surrounding tissue., Methods: Twenty-five patients suffering from high-grade gliomas who were previously treated by surgery and radiotherapy were included. Intraoperatively, two histopathologic samples were obtained a sample of unequivocal tumor tissue (according to anatomical landmarks and the surgeon's visual and tactile impressions) and a small tissue sample obtained using a navigated needle when the surgeon decided to stop the resection. This specimen was considered to be a boundary specimen, where no tumor tissue was apparent. The decision to take the second sample was not influenced by IOUS. The effect of IOUS was analyzed semi-quantitatively., Results: All 25 samples of unequivocal tumor tissue were histopathologically classified as tumor tissue and were hyperechoic on IOUS. Of the boundary specimens, eight were hypoechoic. Only one harbored tumor tissue (P=0.150). Seventeen boundaries were moderately hyperechoic, and these samples contained all possible histological results (i.e., tumor, infiltration, or no tumor)., Conclusion: During surgery performed on relapsed, irradiated, high-grade gliomas, IOUS provided a reliable method of navigating towards the core of the tumor. At borders, it did not reliably distinguish between remnants or tumor-free tissue, but hypoechoic areas seldom contained tumor tissue., Competing Interests: No potential conflict of interest relevant to this article was reported.

Background:  The adaptive immune system has been considered to play a minimal role in the early host response during bacterial meningitis., Methods:  We investigated the progression and outcome of pneumococcal meningitis in Rag1 -/- mice lacking functional B and T cells by assessing overall and symptom-free survival, bacteriological and histological studies, as well as flow cytometry and measurements of proinflammatory mediators., Results:  The intracerebral injection of S. pneumoniae D39 induced the recruitment of B and T cells (CD4 + , γδ and natural killer) into the brain of wild-type mice. Mice with no functional B and T cells developed clinical symptoms and succumbed to the infection earlier than the wild-type group. In the CNS, Rag1 -/- mice showed lower levels of interleukin 1β, reduced microglial proliferation, and impaired granulocyte recruitment with an earlier spread of pneumococci into the bloodstream, compared with wild-type mice. Lack of B and T cells resulted in a severe impairment of bacterial clearance in blood, spleen, and liver and an exaggerated systemic inflammatory response., Conclusions:  B and T cells are important effector cells delaying the spread of pneumococci from the brain to the systemic circulation and shaping the immune response, thereby prolonging the survival of the host in the absence of antibiotic treatment., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Multiple sclerosis is a complex and heterogeneous, most likely autoimmune, demyelinating disease of the central nervous system (CNS). Although a number of histological classification systems for CNS lesions have been used by different groups in recent years, no uniform classification exists. In this paper, we propose a simple and unifying classification of MS lesions incorporating many elements of earlier histological systems that aims to provide guidelines for neuropathologists and researchers studying MS lesions to allow for better comparison of different studies performed with MS tissue, and to aid in understanding the pathogenesis of the disease. Based on the presence/absence and distribution of macrophages/microglia (inflammatory activity) and the presence/absence of ongoing demyelination (demyelinating activity), we suggest differentiating between active, mixed active/inactive, and inactive lesions with or without ongoing demyelination. Active lesions are characterized by macrophages/microglia throughout the lesion area, whereas mixed active/inactive lesions have a hypocellular lesion center with macrophages/microglia limited to the lesion border. Inactive lesions are almost completely lacking macrophages/microglia. Active and mixed active/inactive lesions can be further subdivided into lesions with ongoing myelin destruction (demyelinating lesions) and lesions in which the destruction of myelin has ceased, but macrophages are still present (post-demyelinating lesions). This distinction is based on the presence or absence of myelin degradation products within the cytoplasm of macrophages/microglia. For this classification of MS lesions, identification of myelin with histological stains [such as luxol fast blue-PAS] or by immunohistochemistry using antibodies against myelin basic-protein (MBP) or proteolipid-protein (PLP), as well as, detection of macrophages/microglia by, e.g., anti-CD68 is sufficient. Active and demyelinating lesions may be further subdivided into the early and late demyelinating lesions. The former is defined by the presence in macrophages of major and small molecular weight myelin proteins, such as cyclic nucleotide diphosphoesterase (CNP), myelin oligodendrocyte glycoprotein (MOG), or myelin-associated protein (MAG), whereas macrophages in the latter demonstrate merely the presence of the major myelin proteins MBP or PLP. We discuss the histological features and staining techniques required to classify MS lesions, and, in addition, describe the histological hallmarks of cortical pathology and diffuse white matter changes, as well as of remyelination.

Oligodendrocyte damage is a central event in the pathogenesis of the common neuroinflammatory condition, multiple sclerosis (MS). Where and how oligodendrocyte damage is initiated in MS is not completely understood. Here, we use a combination of light and electron microscopy techniques to provide a dynamic and highly resolved view of oligodendrocyte damage in neuroinflammatory lesions. We show that both in MS and in its animal model structural damage is initiated at the myelin sheaths and only later spreads to the oligodendrocyte cell body. Early myelin damage itself is characterized by the formation of local myelin out-foldings-'myelinosomes'-, which are surrounded by phagocyte processes and promoted in their formation by anti-myelin antibodies and complement. The presence of myelinosomes in actively demyelinating MS lesions suggests that oligodendrocyte damage follows a similar pattern in the human disease, where targeting demyelination by therapeutic interventions remains a major open challenge.

: Fast remyelination by endogenous oligodendrocyte precursor cells (OPCs) is essential to prevent axonal and subsequent retrograde neuronal degeneration in demyelinating lesions in multiple sclerosis (MS). In chronic lesions, however, the remyelination capacity of OPCs becomes insufficient. Cell therapy with exogenous remyelinating cells may be a strategy to replace the failing endogenous OPCs. Here, we differentiated human induced pluripotent stem cells (hiPSCs) into OPCs and validated their proper functionality in vitro as well as in vivo in mouse models for MS. Next, we intracerebrally injected hiPSC-derived OPCs in a nonhuman primate (marmoset) model for progressive MS; the grafted OPCs specifically migrated toward the MS-like lesions in the corpus callosum where they myelinated denuded axons. hiPSC-derived OPCs may become the first therapeutic tool to address demyelination and neurodegeneration in the progressive forms of MS., Significance: This study demonstrates for the first time that human induced pluripotent stem cell (iPSC)-derived oligodendrocyte precursor cells (OPCs), after intracortical implantation in a nonhuman primate model for progressive multiple sclerosis (MS), migrate to the lesions and remyelinate denuded axons. These findings imply that human iPSC-OPCs can be a therapeutic tool for MS. The results of this feasibility study on the potential use of hiPSC-derived OPCs are of great importance for all MS researchers focusing on the stimulation of remyelination in MS patients. Further optimization and research on practical issues related to the safe production and administration of iPSC-derived cell grafts will likely lead to a first clinical trial in a small group of secondary progressive MS patients. This would be the first specific therapeutic approach aimed at restoring myelination and rescuing axons in MS patients, since there is no treatment available for this most debilitating aspect of MS., (©AlphaMed Press.)

Background: Histopathological studies have revealed four different immunopathological patterns of lesion pathology in early multiple sclerosis (MS). Pattern II MS is characterised by immunoglobulin and complement deposition in addition to T-cell and macrophage infiltration and is more likely to respond to plasma exchange therapy, suggesting a contribution of autoantibodies., Objective: To assess the frequency of anti-myelin oligodendrocyte glycoprotein (MOG), anti-M1-aquaporin-4 (AQP4), anti-M23-AQP4, anti-N-methyl-d-aspartate-type glutamate receptors (NMDAR) and 25 other anti-neural antibodies in pattern II MS., Methods: Thirty-nine serum samples from patients with MS who had undergone brain biopsy (n = 24; including 13 from patients with pattern II MS) and from histopathologically non-classified MS patients (n = 15) were tested for anti-MOG, anti-M1-AQP4, anti-M23-AQP4, anti-NMDAR, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-type glutamate receptors (AMPAR), anti-gamma-aminobutyric acid receptors (GABA B R), anti-leucine-rich, glioma-activated protein 1 (LGI1), anti-contactin-associated protein 2 (CASPR2), anti-dipeptidyl-peptidase-like protein-6 (DPPX), anti-Tr/Delta/notch-like epidermal growth factor-related receptor (DNER), anti-Hu, anti-Yo, anti-Ri, anti-Ma1/Ma2, anti-CV2/collapsin response mediator protein 5 (CRMP5), anti-glutamic acid decarboxylase (GAD), anti-amphiphysin, anti-Ca/RhoGTPase-activating protein 26 (ARHGAP26), anti-Sj/inositol-1,4,5-trisphosphate receptor 1 (ITPR1), anti-Homer3, anti-carbonic anhydrase-related protein (CARPVIII), anti-protein kinase gamma (PKCgamma), anti-glutamate receptor delta 2 (GluRdelta2), anti-metabotropic glutamate receptor 1 (mGluR1) and anti-mGluR5, as well as for anti-glial nuclei antibodies (AGNA) and Purkinje cell antibody 2 (PCA2)., Results: Antibodies to MOG belonging to the complement-activating immunoglobulin G1 (IgG1) subclass were detected in a patient with pattern II MS. Detailed brain biopsy findings are shown., Conclusion: This is the largest study on established anti-neural antibodies performed in MS so far. MOG-IgG may play a role in a small percentage of patients diagnosed with pattern II MS., (© The Author(s), 2016.)

Elucidating pathophysiologic mechanisms underlying the spectrum of pediatric-onset CNS demyelinating diseases, particularly those that may distinguish multiple sclerosis (MS) from other entities, promises to both improve diagnostics and guide more-informed therapeutic decisions. Observations that pediatric- and adult-onset MS share the same genetic and environmental risk factors support the view that these conditions represent essentially the same illness manifesting at different ages. Nonetheless, special consideration must be given when CNS inflammation manifests in early life, at a time when multiple organs (including immune and nervous systems) are actively maturing. CSF analysis in pediatric-onset MS points to chronic CNS inflammation, supported by observations from limited pathologic material available for study. Emerging results implicate abnormalities in both effector and regulatory T cell subsets, and potentially immune senescence, in children with MS. Although CNS-directed antibodies (including antibodies recognizing myelin antigens; Kir4.1) can be documented in pediatric-onset MS, their pathophysiologic significance (as in adults) remains unclear. This is in contrast to the presence of serum and/or CSF antibodies recognizing aquaporin-4, which, when measured using validated cell-based assays, supports the diagnosis of a neuromyelitis optica spectrum disorder, distinct from MS. Presence of anti-myelin oligodendrocyte glycoprotein antibodies documented with similar cell-based assays may also be associated with pathophysiologically distinct disease phenotypes in children. The substantial impact of pediatric-onset MS on normal brain development and function underscores the importance of elucidating both the immunobiology and neurobiology of disease. Ongoing efforts are aimed at developing and validating biological measures that define pathophysiologically distinct monophasic and chronic forms of pediatric CNS demyelination., (© 2016 American Academy of Neurology.)

Multiple sclerosis (MS) is the most common cause for sustained disability in young adults, yet treatment options remain very limited. Although numerous therapeutic approaches have been effective in rodent models of experimental autoimmune encephalomyelitis (EAE), only few proved to be beneficial in patients with MS. Hence, there is a strong need for more predictive animal models. Within the past decade, EAE in the common marmoset evolved as a potent, alternative model for MS, with immunological and pathological features resembling more closely the human disease. However, an often very rapid and severe disease course hampers its implementation for systematic testing of new treatment strategies. We here developed a new focal model of EAE in the common marmoset, induced by myelin oligodendrocyte glycoprotein (MOG) immunization and stereotactic injections of proinflammatory cytokines. At the injection site of cytokines, confluent inflammatory demyelinating lesions developed that strongly resembled human MS lesions. In a proof-of-principle treatment study with the immunomodulatory compound laquinimod, we demonstrate that targeted EAE in marmosets provides a promising and valid tool for preclinical experimental treatment trials in MS research., (© 2015 International Society of Neuropathology.)

In the pathogenesis of central nervous system (CNS) demyelinating disorders, antigen-specific B cells are implicated to act as potent antigen-presenting cells (APC), eliciting waves of inflammatory CNS infiltration. Here, we provide the first evidence that CNS-reactive antibodies (Ab) are similarly capable of initiating an encephalitogenic immune response by targeting endogenous CNS antigen to otherwise inert myeloid APC. In a transgenic mouse model, constitutive production of Ab against myelin oligodendrocyte glycoprotein (MOG) was sufficient to promote spontaneous experimental autoimmune encephalomyelitis (EAE) in the absence of B cells, when mice endogenously contained MOG-recognizing T cells. Adoptive transfer studies corroborated that anti-MOG Ab triggered activation and expansion of peripheral MOG-specific T cells in an Fc-dependent manner, subsequently causing EAE. To evaluate the underlying mechanism, anti-MOG Ab were added to a co-culture of myeloid APC and MOG-specific T cells. At otherwise undetected concentrations, anti-MOG Ab enabled Fc-mediated APC recognition of intact MOG; internalized, processed and presented MOG activated naïve T cells to differentiate in an encephalitogenic manner. In a series of translational experiments, anti-MOG Ab from two patients with an acute flare of CNS inflammation likewise facilitated detection of human MOG. Jointly, these observations highlight Ab-mediated opsonization of endogenous CNS auto-antigen as a novel disease- and/or relapse-triggering mechanism in CNS demyelinating disorders.

Objectives: To evaluate the presence of antibodies to conformation-intact myelin oligodendrocyte glycoprotein (MOG) in a subgroup of adult patients with clinically definite multiple sclerosis (MS) preselected for a specific clinical phenotype including severe spinal cord, optic nerve, and brainstem involvement., Methods: Antibodies to MOG were investigated using a cell-based assay in 3 groups of patients: 104 preselected patients with MS (group 1), 55 age- and sex-matched, otherwise unselected patients with MS (group 2), and in 22 brain-biopsied patients with demyelinating diseases of the CNS (n = 19 with MS), 4 of whom classified as MS type II (group 3). Recognized epitopes were identified with mutated variants of MOG., Results: Antibodies to MOG were found in about 5% (5/104) of preselected adult patients with MS. In contrast, in groups 2 and 3, none of the patients tested positive for MOG antibodies. Patients with MS with antibodies to MOG predominantly manifested with concomitant severe brainstem and spinal cord involvement and had a severe disease course with high relapse rates and failure to several disease-modifying therapies. Three of them had been treated with plasma exchange with a favorable response. All anti-MOG-positive patients with MS showed typical MS lesions on brain MRI. Longitudinal analysis up to 9 years revealed fluctuations and reappearance of anti-MOG reactivity. Epitope mapping indicated interindividual heterogeneity, yet intraindividual stability of the antibody response., Conclusions: Antibodies to MOG can be found in a distinct subgroup of adult MS with a specific clinical phenotype and may indicate disease heterogeneity.

Childhood trauma is a well-described risk factor for the development of stress-related psychopathology such as posttraumatic stress disorder or depression later in life. Childhood adversity can be modeled in rodents by juvenile stress (JS) protocols, resulting in impaired coping with stressful challenges in adulthood. In the current study, we investigated the long-lasting impact of JS on the expression of molecular factors for glutamate and γ-aminobutyric acid (GABA) uptake and turnover in sublayers of the dentate gyrus (DG) using laser microdissection and quantitative real-time polymerase chain reaction. We observed reduced mRNA expression levels after JS for factors mediating astrocytic glutamate and GABA uptake and degradation. These alterations were prominently observed in the dorsal but not ventral DG granule cell layer, indicating a lasting change in astrocytic GABA and glutamate metabolism that may affect dorsal DG network activity. Indeed, we observed increased inhibition and a lack of facilitation in response to paired-pulse stimulation at short interstimulus intervals in the dorsal DG after JS, while no alterations were evident in basal synaptic transmission or forms of long-term plasticity. The shift in paired-pulse response was mimicked by pharmacologically blocking the astrocytic GABA transporter GAT-3 in naïve animals. Accordingly, reduced expression levels of GAT-3 were confirmed at the protein level in the dorsal granule cell layer of rats stressed in juvenility. Together, these data demonstrate a lasting shift in the excitatory/inhibitory balance of dorsal DG network activity by JS that appears to be mediated by decreased GABA uptake into astrocytes., (© 2016 Wiley Periodicals, Inc.)

With the approval of various substances for the immunotherapy of multiple sclerosis (MS), treatment possibilities have improved significantly over the last few years. Indeed, the choice of individually tailored preparations and treatment monitoring for the treating doctor is becoming increasingly more complex. This is particularly applicable for monitoring for a treatment-induced compromise of the immune system. The following article by members of the German Multiple Sclerosis Skills Network (KKNMS) and the task force "Provision Structures and Therapeutics" summarizes the practical recommendations for approved immunotherapy for mild to moderate and for (highly) active courses of MS. The focus is on elucidating the substance-specific relevance of particular laboratory parameters with regard to the mechanism of action and the side effects profile. To enable appropriate action to be taken in clinical practice, any blood work changes that can be expected, in addition to any undesirable laboratory findings and their causes and relevance, should be elucidated.

Objective: To test whether Toll-like receptor (TLR) signaling plays a key role for reduced nuclear factor B (NF-κB) activation after laquinimod treatment in the model of cuprizone-induced demyelination, oligodendrocyte apoptosis, inflammation, and axonal damage., Methods: Ten-week-old C57BL/6J, TLR4(-/-), and MyD88(-/-) mice received 0.25% cuprizone for 6 weeks and were treated daily with 25 mg/kg laquinimod or vehicle. After 6 weeks of demyelination, extent of demyelination, oligodendrocyte density, microglia infiltration, and axonal damage were analyzed in the corpus callosum. Additionally, we analyzed primary mouse astrocytes from C57BL/6J, TLR4(-/-), MyD88(-/-), and TRIF(-/-) mice for alteration in NF-κB signaling., Results: Vehicle-treated controls from C57BL/6J, TLR4(-/-), and MyD88(-/-) mice displayed extensive callosal demyelination as well as microglial activation. In contrast, mice treated with 25 mg/kg laquinimod showed mainly intact callosal myelin. The demyelination score was significantly higher in all untreated mice compared to mice treated with laquinimod. There were significantly fewer APP-positive axonal spheroids, Mac3-positive macrophages/microglia, and less oligodendrocyte apoptosis in the corpus callosum of laquinimod-treated mice in comparison to untreated controls. Stimulated primary mouse astrocytes from laquinimod-treated groups show reduced NF-κB activation compared to vehicle-treated controls., Conclusions: Our results confirm that laquinimod prevents demyelination in the cuprizone mouse model for multiple sclerosis via downregulation of NF-κB activation. This laquinimod effect, however, does not involve upstream Toll-like receptor signaling.

Microglia, innate immune cells of the CNS, sense infection and damage through overlapping receptor sets. Toll-like receptor (TLR) 4 recognizes bacterial lipopolysaccharide (LPS) and multiple injury-associated factors. We show that its co-receptor CD14 serves three non-redundant functions in microglia. First, it confers an up to 100-fold higher LPS sensitivity compared to peripheral macrophages to enable efficient proinflammatory cytokine induction. Second, CD14 prevents excessive responses to massive LPS challenges via an interferon β-mediated feedback. Third, CD14 is mandatory for microglial reactions to tissue damage-associated signals. In mice, these functions are essential for balanced CNS responses to bacterial infection, traumatic and ischemic injuries, since CD14 deficiency causes either hypo- or hyperinflammation, insufficient or exaggerated immune cell recruitment or worsened stroke outcomes. While CD14 orchestrates functions of TLR4 and related immune receptors, it is itself regulated by TLR and non-TLR systems to thereby fine-tune microglial damage-sensing capacity upon infectious and non-infectious CNS challenges., (© 2015 Wiley Periodicals, Inc.)

Multiple sclerosis is a chronic inflammatory disease with primary demyelination and neurodegeneration in the central nervous system. In our study we analysed demyelination and neurodegeneration in a large series of multiple sclerosis brains and provide a map that displays the frequency of different brain areas to be affected by these processes. Demyelination in the cerebral cortex was related to inflammatory infiltrates in the meninges, which was pronounced in invaginations of the brain surface (sulci) and possibly promoted by low flow of the cerebrospinal fluid in these areas. Focal demyelinated lesions in the white matter occurred at sites with high venous density and additionally accumulated in watershed areas of low arterial blood supply. Two different patterns of neurodegeneration in the cortex were identified: oxidative injury of cortical neurons and retrograde neurodegeneration due to axonal injury in the white matter. While oxidative injury was related to the inflammatory process in the meninges and pronounced in actively demyelinating cortical lesions, retrograde degeneration was mainly related to demyelinated lesions and axonal loss in the white matter. Our data show that accumulation of lesions and neurodegeneration in the multiple sclerosis brain does not affect all brain regions equally and provides the pathological basis for the selection of brain areas for monitoring regional injury and atrophy development in future magnetic resonance imaging studies., (© The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)-positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS)., Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20)., Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD., Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS.

Objectives: HIV infection affects the central nervous system (CNS), frequently causing cognitive impairment. Hippocampal injury impedes the ability to transfer information into memory. Therefore, we aimed to examine neuronal injury and repair in the hippocampal formation in HIV encephalopathy., Methods: We compared neuropathological findings in 14 autopsy cases after death from systemic complications of HIV infection and in 15 age-matched HIV-negative control cases after sudden death from nonneurological causes using immunohistochemistry., Results: The density of apoptotic granule cells in the dentate gyrus was higher in HIV-infected than in control cases (P = 0.048). Proliferation of neural progenitor cells in the dentate gyrus was increased in HIV infection (P = 0.028), whereas the density of recently generated TUC-4 [TOAD (turned on after division)/Ulip/CRMP family 4]-expressing neurons in this region was not significantly elevated in HIV-infected cases (P = 0.13). HIV infection caused microglial activation and astrocytosis in the neocortex and hippocampal formation. Conversely, we were unable to detect more pronounced axonal injury in HIV-infected than in control cases., Conclusions: As in other infections involving the CNS, apoptosis of hippocampal neurons accompanied by microglial activation and astrocytosis is a prominent feature of HIV encephalopathy. The regenerative potential, assessed using the density of young neurons in the hippocampal dentate gyrus, in HIV infection appears to be lower than in acute bacterial meningitis and septic encephalitis., (© 2015 British HIV Association.)

Grey matter pathology has emerged as an important contributor to long-term disability in multiple sclerosis. To better understand where and how neuronal damage in the grey matter is initiated, we used high resolution confocal microscopy of Golgi-Cox impregnated tissue sections and reconstructed single cortical projection neurons in autopsies from eight patients with long-standing relapsing-remitting or secondary progressive multiple sclerosis and eight control patients without neurological disease. Analysis of several hundred individual neurons located in the insular, frontotemporal and occipital lobe revealed a widespread and pronounced loss of dendritic spines in multiple sclerosis cortex that occurs independent of cortical demyelination and axon loss. The presence of a primary synaptic pathology in the normal-appearing cortex of multiple sclerosis patients challenges current disease concepts and has important implications for our understanding of disease progression., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an inflammatory disorder of the central nervous system; it has only recently been defined and to date has received only limited attention. Its cause is as yet unknown. The pathologic characteristics are infiltration of T lymphocytes into the perivascular spaces of the pons, responsiveness to immunotherapy, and gadolinium-enhancing punctiform lesions in the brainstem seen on magnetic resonance imaging (MRI)., Case Description: We report here on the clinical, MRI, and brain biopsy findings in a 68-year-old man who presented with dysphagia, numbness and paresthesia on the right side of his face, as well as progressive gait ataxia. Brain and spinal MRI showed lesions in the pons and in the cervical spinal cord. The pontine lesion became progressively larger extending to the middle cerebellar peduncle and a tumor was suspected. After repeated biopsy, the histopathologic diagnosis confirmed CLIPPERS., Conclusions: CLIPPERS syndrome may become manifest with a progressive tumor-like pontine lesion. This report adds clinical and radiologic aspects to the limited number of CLIPPERS cases reported to date, and underlines the importance of considering CLIPPERS in the differential diagnosis of tumor-like pontine processes., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: An extensive analysis of white matter plaques in a large sample of multiple sclerosis (MS) autopsies provides insights into the dynamic nature of MS pathology., Methods: One hundred twenty MS cases (1,220 tissue blocks) were included. Plaque types were classified according to demyelinating activity based on stringent criteria. Early active, late active, smoldering, inactive, and shadow plaques were distinguished. A total of 2,476 MS white matter plaques were identified. Plaque type distribution was analyzed in relation to clinical data., Results: Active plaques were most often found in early disease, whereas at later stages, smoldering, inactive, and shadow plaques predominated. The presence of early active plaques rapidly declined with disease duration. Plaque type distribution differed significantly by clinical course. The majority of plaques in acute monophasic and relapsing-remitting MS (RRMS) were active. Among secondary progressive MS (SPMS) cases with attacks, all plaque types could be distinguished including active plaques, in contrast to SPMS without attacks, in which inactive plaques predominated. Smoldering plaques were frequently and almost exclusively found in progressive MS. At 47 years of age, an equilibrium was observed between active and inactive plaques, whereas smoldering plaques began to peak. Men displayed a higher proportion of smoldering plaques., Interpretation: Disease duration, clinical course, age, and gender contribute to the dynamic nature of white matter MS pathology. Active MS plaques predominate in acute and early RRMS and are the likely substrate of clinical attacks. Progressive MS transitions to an accumulation of smoldering plaques characterized by microglial activation and slow expansion of pre-existing plaques. Whether current MS therapeutics impact this pathological driver of disease progression remains uncertain., (© 2015 American Neurological Association.)

In recent years the approval of new substances has led to a substantial increase in the number of course-modifying immunotherapies available for multiple sclerosis. Therapy conversion therefore represents an increasing challenge. The treatment options sometimes show complex adverse effect profiles and necessitate a long-term and comprehensive monitoring. This article presents an overview of therapy conversion of immunotherapies for multiple sclerosis in accordance with the recommendations of the Disease-Related Competence Network for Multiple Sclerosis and the German Multiple Sclerosis Society as well as the guidelines on diagnostics and therapy for multiple sclerosis of the German Society of Neurology and the latest research results. At the present point in time it should be noted that no studies have been carried out for most of the approaches for therapy conversion given here; however, the recommendations are based on theoretical considerations and therefore correspond to recommendations at the level of expert consensus, which is currently essential for the clinical daily routine.

Progressive multifocal leukoencephalopathy (PML) has recently been described in psoriasis or multiple sclerosis patients treated with fumaric acid esters (fumarates), who had developed severe and long-standing lymphocytopenia (<500/mm(3) ). We report a psoriasis patient who presented with progressive neurologic dysfunction and seizures after 2.5 years of fumarate therapy. Despite absolute lymphocyte counts remaining between 500-1000/mm(3) , his CD4(+) and CD8(+) T-cell counts were markedly low. MRI showed right hemispheric and brainstem lesions and JC virus DNA was undetectable in his cerebrospinal fluid. Brain biopsy revealed typical features of PML as well as JC virus-infected neurons. Clinicians should consider PML in the differential diagnosis of fumarate-treated patients presenting with brain lesions or seizures even in the absence of severe lymphocytopenia., (© 2015 American Neurological Association.)

Aims: Natalizumab is a humanized monoclonal antibody specific for CD49d receptors of integrins. It inhibits the entry of inflammatory cells into the central nervous system and is approved for the treatment of relapsing-remitting multiple sclerosis (MS). Several lines of evidence indicate an involvement of B cells and plasma cells in MS pathogenesis. However, treatment with the natalizumab analogon PS/2 immunoglobulin G (IgG) has so far only been investigated in T cell-mediated animal models of MS. Due to the importance of B lineage cells in the pathogenesis of MS, the objective of the present study has thus been to analyse the effects of PS/2 IgG in a mouse model of MS with T and B cell cooperation (OSE mice)., Methods: OSE mice were treated with the natalizumab analogon PS/2 IgG either at disease onset or after peak of disease. Treatment was also performed with PS/2 F(ab')2 fragments., Results: PS/2 IgG treatment improved the clinical outcome and decreased spinal cord demyelination and immune cell infiltration if given early in the disease course. Treatment increased blood leukocytes and resulted in a partial internalization of CD49d in T and B cells. The therapeutic effects of PS/2 IgG injections were independent of the Fc fragment as F(ab')2 injections were equally beneficial. In contrast, PS/2 IgG was not effective when given late in the disease course., Conclusions: Results indicate that natalizumab may also be beneficial in MS with B cell-driven immunopathogenesis., (© 2015 British Neuropathological Society.)

Objective: Multiple sclerosis (MS) is a disease of the central nervous system with marked heterogeneity in several aspects including pathological processes. Based on infiltrating immune cells, deposition of humoral factors and loss of oligodendrocytes and/or myelin proteins, four lesion patterns have been described. Pattern II is characterized by antibody and complement deposition in addition to T-cell infiltration. MS is considered a T-cell-mediated disease, but until now the study of pathogenic T cells has encountered major challenges, most importantly the limited access of brain-infiltrating T cells. Our objective was to identify, isolate, and characterize brain-infiltrating clonally expanded T cells in pattern II MS lesions., Methods: We used next-generation sequencing to identify clonally expanded T cells in demyelinating pattern II brain autopsy lesions, subsequently isolated these as T-cell clones from autologous cerebrospinal fluid and functionally characterized them., Results: We identified clonally expanded CD8(+) but also CD4(+) T cells in demyelinating pattern II lesions and for the first time were able to isolate these as live T-cell clones. The functional characterization shows that T cells releasing Th2 cytokines and able to provide B cell help dominate the T-cell infiltrate in pattern II brain lesions., Interpretation: Our data provide the first functional evidence for a putative role of Th2/Tc2 cells in pattern II MS supporting the existence of this pathogenic phenotype and questioning the protective role that is generally ascribed to Th2 cells. Our observations are important to consider for future treatments of pattern II MS patients.

Tumors of the pineal region (PR) are rare and can be subdivided into four main histomorphological groups: Pineal-parenchymal tumors (PPT), germ cell tumors (GCT), glial tumors and miscellaneous tumors. The appropriate pathological classification and grading of these malignancies is essential for determining the clinical management and prognosis. However, an early diagnosis is often delayed due to unspecific clinical symptoms, and histological support is not always decisive to identify the diversity of tumors of the PR. The present study aimed to characterize 18 tumors of the PR using comparative genomic hybridization. All the tumors were primarily surgically resected without any previous irradiation or chemotherapy. In addition to chromosomal aberrations in PPT and different GCTs of the PR, the present study described, for the first time, the chromosomal changes in a few rare entities (solitary-fibrous and neuroendocrine tumors) of the PR. The tumors in the study, regardless of histology and World Health Organization grade, were characterized by frequent gains at 7, 9q, 12q, 16p, 17 and 22q, and losses at 13q. While the detection of chromosomal aberrations in these tumors appears not to be indicative enough of histological entities and their grade of malignancy, the present data may be of use to select genes of interest for higher resolution genomic analyses.

Remyelination capacity decreases with age in adult mice, but data comparing remyelination capacity after toxic demyelination in developing mice versus adult mice are not available. We treated 3-week-old and adult C57BL/6 mice with cuprizone for 1 to 5 weeks and studied demyelination/remyelination and cellular reactions in the corpus callosum and motor cortex by histology, immunohistochemistry, and electron microscopy. We compared results between the 2 treated groups and age-matched controls. In juvenile mice, significant demyelination was detectable in the corpus callosum on Week 2 and in the motor cortex on Week 5. Oligodendrocyte loss, microglial activation, and acute axonal damage peaked on Week 2. Increased numbers of oligodendrocyte precursor cells were evident on Week 1, and remyelination was detectable on Week 3. Juvenile mice showed more rapid demyelination than adult mice, which may be related to greater vulnerability of oligodendrocytes, lower myelin content, or dose-dependent cuprizone effects. Earlier activation of microglia and proliferation of oligodendrocyte precursor cells probably contributed to accelerated remyelination and less pronounced axonal damage. Our data indicate that oligodendroglial regeneration and remyelination are enhanced in the maturing rodent brain compared with the young-adult rodent brain.

Inflammatory changes have been postulated to contribute to secondary brain injury after aneurysmal subarachnoid hemorrhage (SAH). In human specimens after SAH as well as in experimental SAH using mice, we show an intracerebral accumulation of inflammatory cells between days 4 and 28 after the bleeding. Using bone marrow chimeric mice allowing tracing of all peripherally derived immune cells, we confirm a truly CNS-intrinsic, microglial origin of these immune cells, exhibiting an inflammatory state, and rule out invasion of myeloid cells from the periphery into the brain. Furthermore, we detect secondary neuro-axonal injury throughout the time course of SAH. Since neuronal cell death and microglia accumulation follow a similar time course, we addressed whether the occurrence of activated microglia and neuro-axonal injury upon SAH are causally linked by depleting microglia in vivo. Given that the amount of neuronal cell death was significantly reduced after microglia depletion, we conclude that microglia accumulation inflicts secondary brain injury after SAH.

Oxidative injury appears to play a major role in the propagation of demyelination and neurodegeneration in multiple sclerosis (MS). It has been suggested that endogenous anti-oxidant defense mechanisms within MS lesions are insufficient to prevent spreading of damage. Thus, current therapeutic approaches (e.g., fumarate treatment) target to up-regulate the expression of a key regulator of anti-oxidative defense, the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2). In this study, we show that Nrf2 is already strongly up-regulated in active MS lesions. Nuclear Nrf2 expression was particularly observed in oligodendrocytes and its functional activity is indicated by the expression of one of its downstream targets (heme oxygenase 1) in the same cells. In contrast, only a minor number of Nrf2-positive neurons were detected, even in highly inflammatory cortical lesions presenting with extensive oxidative injury. Overall, the most pronounced Nrf2 expression was found in degenerating cells, which showed signs of apoptotic or necrotic cell death. Via whole-genome microarray analyses of MS lesions, we observed a differential expression of numerous Nrf2-responsive genes, also involved in the defense against oxidative stress, predominantly in areas of initial myelin destruction within actively demyelinating white matter lesions. Furthermore, the expression patterns of Nrf2-induced genes differed between the white matter and cortical gray matter. Our study shows that in the MS brain, Nrf2 expression varies in different cell types and is associated with active demyelination in the lesions.

Lymphocytes express potassium channels that regulate physiological cell functions, such as activation, proliferation and migration. Expression levels of K2P5.1 (TASK2; KCNK5) channels belonging to the family of two-pore domain potassium channels have previously been correlated to the activity of autoreactive T lymphocytes in patients with multiple sclerosis and rheumatoid arthritis. In humans, K2P5.1 channels are upregulated upon T cell stimulation and influence T cell effector functions. However, a further clinical translation of targeting K2P5.1 is currently hampered by a lack of highly selective inhibitors, making it necessary to evaluate the impact of KCNK5 in established preclinical animal disease models. We here demonstrate that K2P5.1 knockout (K2P5.1-/-) mice display no significant alterations concerning T cell cytokine production, proliferation rates, surface marker molecules or signaling pathways. In an experimental model of autoimmune neuroinflammation, K2P5.1-/- mice show a comparable disease course to wild-type animals and no major changes in the peripheral immune system or CNS compartment. A compensatory upregulation of the potassium channels K2P3.1 and KV1.3 seems to counterbalance the deletion of K2P5.1. As an alternative model mimicking autoimmune neuroinflammation, experimental autoimmune encephalomyelitis in the common marmoset has been proposed, especially for testing the efficacy of new potential drugs. Initial experiments show that K2P5.1 is functionally expressed on marmoset T lymphocytes, opening up the possibility for assessing future K2P5.1-targeting drugs.

Chronic muscular limb pain requires the adoption of motor patterns distinct from the classic ipsilateral flexion, crossed extension and corresponding reciprocal inhibitions to acute exteroceptive stimulation. Using selective chemical activation of group III/IV afferents in gastrocnemius-soleus (GS) muscles we investigated bilaterally their reflex responses conditioned by (a) acute 'myositis' induced by intramuscular carrageenan; and (b) sub-acute 'myositis' induced by infusion of complete Freund's adjuvant (CFA). Reflex transmission was detected by monosynaptic testing and c-fos staining used to identify increased neuronal activity. In all control experiments with chemical stimulation of group III/IV afferents, ipsilateral responses conformed to the flexor reflex pattern. However, the expected contralateral facilitation of GS motoneurones occurred in fewer than 50% trials while only 9% of trials induced contralateral inhibition of flexor posterior-biceps-semitendinosus (PBSt) motoneurones. During carrageenan acute myositis contralateral PBSt was transiently facilitated by selective activation of group III/IV afferents. During CFA-induced myositis, contralateral only inhibition of GS motoneurones occurred instead of any facilitation, while bidirectionally a crossed facilitation of PBST dominated. These reflex changes were mirrored in an enhanced number of neurones with enhanced c-fos expression. Muscle pain, particularly if chronically persistent, requires another behavioural response pattern than acute exteroceptive pain., (Copyright © 2015 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.)

The putative protein tyrosine kinase (PTK) inhibitor tyrphostin AG126 has proven beneficial in various models of inflammatory disease. Yet molecular targets and cellular mechanisms remained enigmatic. We demonstrate here that AG126 treatment has beneficial effects in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. AG126 alleviates the clinical symptoms, diminishes encephalitogenic Th17 differentiation, reduces inflammatory CNS infiltration as well as microglia activation and attenuates myelin damage. We show that AG126 directly inhibits Bruton's tyrosine kinase (BTK), a PTK associated with B cell receptor and Toll-like receptor (TLR) signaling. However, BTK inhibition cannot account for the entire activity spectrum. Effects on TLR-induced proinflammatory cytokine expression in microglia involve AG126 hydrolysis and conversion of its dinitrile side chain to malononitrile (MN). Notably, while liberated MN can subsequently mediate critical AG126 features, full protection in EAE still requires delivery of intact AG126. Its anti-inflammatory potential and especially interference with TLR signaling thus rely on a dual mechanism encompassing BTK and a novel MN-sensitive target. Both principles bear great potential for the therapeutic management of disturbed innate and adaptive immune functions., (© 2015 Wiley Periodicals, Inc.)

Subpial cortical demyelination (SCD) accounts for the greatest proportion of demyelinated cortex in multiple sclerosis (MS). SCD is already found in biopsy cases with early MS and in marmosets with experimental autoimmune encephalomyelitis (EAE), but the pathogenesis of SCD is not well understood. The objective of this study was to investigate whether and, if so, which meningeal inflammatory cells were associated with early SCD in marmosets with EAE. Immunohistochemistry was performed to analyze brain samples from eight control animals and eight marmosets immunized with myelin oligodendrocyte glycoprotein. Meningeal T, B and plasma cells were quantified adjacent to SCD, normal-appearing EAE cortex (NAC) and control marmoset cortex. SCD areas appeared mostly hypocellular with low-grade microglial activation. In marmosets with EAE, meninges adjacent to SCD showed significantly increased T cells paralleled by elevated plasma cells, but unaltered B cell numbers compared with NAC. The elevation of meningeal T and plasma cells was a specific finding topographically associated with SCD, as the meninges overlying NAC displayed similarly low T, B and plasma cell numbers as control cortex. These findings suggest that local meningeal T and plasma cell infiltration contributes to the pathogenesis of SCD in marmosets with EAE., (© 2014 International Society of Neuropathology.)