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1.  Cell type-specific Nrf2 expression in multiple sclerosis lesions 
Acta Neuropathologica  2015;130(2):263-277.
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.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-015-1452-x) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-015-1452-x
PMCID: PMC4503875  PMID: 26087903
Multiple sclerosis; Nrf2; Oxidative stress; Demyelination; Neurodegeneration; Fumarate; BG12
2.  Pathologic Heterogeneity Persists in Early Active Multiple Sclerosis Lesions 
Annals of neurology  2014;75(5):728-738.
Objective
Multiple sclerosis (MS) lesions demonstrate immunopathological heterogeneity in patterns of demyelination. Previous cross-sectional studies reported immunopatterns of demyelination were identical among multiple active demyelinating lesions from the same individual, but differed between individuals, leading to the hypothesis of intraindividual pathological homogeneity and interindividual heterogeneity. Other groups suggested a time-dependent heterogeneity of lesions. The objective of our present study was to analyze tissue samples collected longitudinally to determine whether patterns of demyelination persist over time within a given patient.
Methods
Archival tissue samples derived from patients with pathologically confirmed CNS inflammatory demyelinating disease who had undergone either diagnostic serial biopsy or biopsy followed by autopsy, were analyzed immunohistochemically. Inclusion criteria was the presence of early active demyelinating lesions - required for immunopattern classification - obtained from the same patient at two or more time points.
Results
Among 1321 surgical biopsies consistent with MS, 22 cases met study inclusion criteria. Twenty-one patients (95%) showed a persistence of immunopathological patterns in tissue sampled from different time points. This persistence was demonstrated for all major patterns of demyelination. A single patient showed features suggestive of both pattern II and pattern III on biopsy, but only pattern II among all active lesions examined at autopsy.
Interpretation
These findings continue to support the concept of patient-dependent immunopathological heterogeneity in early MS and suggest that the mechanisms and targets of tissue injury may differ among patient subgroups. These observations have potentially significant implications for individualized therapeutic approaches.
doi:10.1002/ana.24163
PMCID: PMC4070313  PMID: 24771535
Multiple sclerosis; histopathology; intra-individual; homogeneity; heterogeneity; active demyelination; persistence over time
5.  Higher mortality and impaired elimination of bacteria in aged mice after intracerebral infection with E. coli are associated with an age-related decline of microglia and macrophage functions 
Oncotarget  2014;5(24):12573-12592.
Incidence and mortality of bacterial meningitis are strongly increased in aged compared to younger adults demanding new strategies to improve prevention and therapy of bacterial central nervous system (CNS) infections the elderly.
Here, we established a geriatric mouse model for an intracerebral E. coli infection which reflects the clinical situation in aged patients: After intracerebral challenge with E. coli K1, aged mice showed a higher mortality, a faster development of clinical symptoms, and a more pronounced weight loss. Elimination of bacteria and systemic inflammatory response were impaired in aged mice, however, the number of infiltrating leukocytes and microglial cells in the CNS of aged and young mice did not differ substantially.
In vitro, primary microglial cells and peritoneal macrophages from aged mice phagocytosed less E. coli and released less NO and cyto-/chemokines compared to cells from young mice both without activation and after stimulation by agonists of TLR 2, 4, and 9.
Our results suggest that the age-related decline of microglia and macrophage functions plays an essential role for the higher susceptibility of aged mice to intracerebral infections. Strategies to improve the phagocytic potential of aged microglial cells and macrophages appear promising for prevention and treatment of CNS infections in elderly patients.
PMCID: PMC4350342  PMID: 25528768
aging; bacterial CNS infection; phagocytosis; microglia; Toll-like receptor
6.  Early loss of oligodendrocytes in human and experimental neuromyelitis optica lesions 
Acta neuropathologica  2013;127(4):523-538.
Neuromyelitis optica (NMO) is a chronic, mostly relapsing inflammatory demyelinating disease of the CNS characterized by serum anti-aquaporin 4 (AQP4) antibodies in the majority of patients. Anti-AQP4 antibodies derived from NMO patients target and deplete astrocytes in experimental models when co-injected with complement. However, the time course and mechanisms of oligodendrocyte loss and demyelination and the fate of oligodendrocyte precursor cells (OPC) have not been examined in detail. Also, no studies regarding astrocyte repopulation of experimental NMO lesions have been reported. We utilized two rat models using either systemic transfer or focal intracerebral injection of recombinant human anti-AQP4 antibodies to generate NMO-like lesions. Time-course experiments were performed to examine oligodendroglial and astroglial damage and repair. In addition, oligodendrocyte pathology was studied in early human NMO lesions. Apart from early complement-mediated astrocyte destruction, we observed a prominent, very early loss of oligodendrocytes and oligodendrocyte precursor cells (OPCs) as well as a delayed loss of myelin. Astrocyte repopulation of focal NMO lesions was already substantial after 1 week. Olig2-positive OPCs reappeared before NogoA-positive, mature oligodendrocytes. Thus, using two experimental models that closely mimic the human disease, our study demonstrates that oligodendrocyte and OPC loss is an extremely early feature in the formation of human and experimental NMO lesions and leads to subsequent, delayed demyelination, highlighting an important difference in the pathogenesis of MS and NMO.
doi:10.1007/s00401-013-1220-8
PMCID: PMC4229038  PMID: 24292009
Neuromyelitis optica; Demyelination; Oligodendrocyte death; Experimental autoimmune encephalomyelitis; Astrocyte
7.  Therapeutic Decisions In Multiple Sclerosis: Moving Beyond Efficacy 
JAMA neurology  2013;70(10):1315-1324.
Importance
Several innovative disease-modifying treatments (DMTs) for relapsing remitting multiple sclerosis (RRMS) have been licensed recently, or are in late-stage development. The molecular targets of several of these DMTs are well defined. All affect at least one of four properties: (1) immune cell trafficking, (2) cell depletion, (3) immune cell function, or (4) cell replication. In contrast to β-interferons and glatiramer acetate, the first generation DMTs, several newer therapies are imbued with safety issues. In addition to efficacy, understanding the relationship between the mechanism of action (MOA) of the DMTs and their safety profile is essential for decision-making in patient care.
Objective
In this article, we relate safety issues of newer DMTs to their pharmacological characteristics, including molecular targets, MOA, chemical structure, and metabolism. Some newer DMTs also represent repurposing or modifications of previous treatments used in other diseases. Here, we describe how identification and understanding of adverse events (AEs) observed with these established drugs within the same class, provide clues regarding safety and toxicities of newer MS therapeutics.
Conclusions and relevance
While understanding mechanisms underlying DMT toxicities is incomplete, it is important to further develop this knowledge to minimize risk to patients, and to ensure future therapies have the most advantageous risk-benefit profiles. Recognizing the individual classes of DMTs described here may be beneficial when considering use of such agents sequentially and possibly in combination.
doi:10.1001/jamaneurol.2013.3510
PMCID: PMC4106803  PMID: 23921521
Multiple sclerosis; disease-modifying treatments; safety; mechanism of action; metabolism
8.  Accumulation and therapeutic modulation of 6-sulfo LacNAc+ dendritic cells in multiple sclerosis 
Objective:
To examine the potential role of 6-sulfo LacNAc+ (slan) dendritic cells (DCs) displaying pronounced proinflammatory properties in the pathogenesis of multiple sclerosis (MS).
Methods:
We determined the presence of slanDCs in demyelinated brain lesions and CSF samples of patients with MS. In addition, we explored the impact of methylprednisolone, interferon-β, glatiramer acetate, or natalizumab on the frequency of blood-circulating slanDCs in patients with MS. We also evaluated whether interferon-β modulates important proinflammatory capabilities of slanDCs.
Results:
SlanDCs accumulate in highly inflammatory brain lesions and are present in the majority of CSF samples of patients with MS. Short-term methylprednisolone administration reduces the percentage of slanDCs in blood of patients with MS and the proportion of tumor necrosis factor-α– or CD150-expressing slanDCs. Long-term interferon-β treatment decreases the percentage of blood-circulating slanDCs in contrast to glatiramer acetate or natalizumab. Furthermore, interferon-β inhibits the secretion of proinflammatory cytokines by slanDCs and their capacity to promote proliferation and differentiation of T cells.
Conclusion:
Accumulation of slanDCs in highly inflammatory brain lesions and their presence in CSF indicate that slanDCs may play an important role in the immunopathogenesis of MS. The reduction of blood-circulating slanDCs and the inhibition of their proinflammatory properties by methylprednisolone and interferon-β may contribute to the therapeutic efficiency of these drugs in patients with MS.
doi:10.1212/NXI.0000000000000033
PMCID: PMC4204231  PMID: 25340085
9.  Developmental maturation of innate immune cell function correlates with age-associated susceptibility to central nervous system autoimmunity 
European journal of immunology  2013;43(8):2078-2088.
Multiple sclerosis (MS) is an inflammatory central nervous system (CNS) disorder, which typically occurs in early adulthood while it is rare in children. We tested in the MS-model, experimental autoimmune encephalomyelitis (EAE), whether functional maturation of innate immune cells may determine susceptibility to CNS autoimmune disease. 2 week-old mice were resistant to active EAE causing fulminant paralysis in adult mice, which was associated with an impaired development of Th1- and Th17 cells. Resistant, young mice contained a higher frequency of myeloid derived suppressor cells and plasmacytoid dendritic cells. Further, myeloid antigen-presenting cells (APC) as well as B-cells expressed lower levels of MHC class II and CD40, produced decreased amounts of pro-inflammatory cytokines, while release of anti-inflammatory IL-10 was enhanced. When used as APC, splenocytes from 2 week-old mice failed to differentiate naïve T-cells into Th1- and Th17 cells irrespective of the T-cell donor's age, and promoted development of regulatory T-cells and Th2 cells instead. Adoptive transfer of adult APC restored the ability of 2 week-old mice to generate encephalitogenic T-cells and to develop EAE. Collectively, these findings indicate that the innate immune cell compartment functionally matures during development which may be a prerequisite for development of T-cell-mediated CNS autoimmune disease.
doi:10.1002/eji.201343338
PMCID: PMC4136766  PMID: 23637087
multiple sclerosis; experimental autoimmune encephalomyelitis; age; susceptibility; antigen-presenting cells; MHC class II; co-stimulatory molecules; myeloid-derived suppressor cells; plasmacytoid dendritic cells; development; maturation
10.  Intrathecal anti-CD20 efficiently depletes meningeal B cells in CNS autoimmunity 
Clinical trials revealed that systemic administration of B-cell-depleting anti-CD20 antibodies can hold lesion formation in the early relapsing-remitting phase of multiple sclerosis (MS). Throughout the secondary-progressive (SP) course of MS, pathogenic B cells may, however, progressively replicate within the central nervous system (CNS) itself, which is largely inaccessible to systemic anti-CD20 treatment. Utilizing the murine MS model of experimental autoimmune encephalomyelitis, we show that intrathecal (i.t.) administration of anti-CD20 alone very efficiently depletes meningeal B cells from established CNS lesions. In SP-MS patients, adding i.t. administration of anti-CD20 to its systemic use may be a valuable strategy to target pathogenic B-cell function.
doi:10.1002/acn3.71
PMCID: PMC4184778  PMID: 25356419
11.  Laquinimod reduces neuroaxonal injury through inhibiting microglial activation 
Objective
Laquinimod is an emerging oral medication for multiple sclerosis (MS) that reduces brain atrophy and progression of disability in two Phase III clinical trials. The mechanism of these effects is unclear. Persistent activation of microglia occurs in MS and contributes to injury. Thus, we investigated whether laquinimod alters properties of microglia in culture and in experimental autoimmune encephalomyelitis (EAE), and whether this reduces neurodegeneration.
Methods
Microglia were cultured from human brains. EAE was induced in mice.
Results
The activation of human microglia increased levels of several pro- and anti-inflammatory cytokines and these elevations were attenuated by pretreatment with laquinimod. Laquinimod prevented the decline in activated microglia of miR124a, a microRNA implicated in maintaining microglia quiescence, and reduced the activity of several signaling pathways (Jun-N-terminal kinase, ribosomal S6 kinase, and AKT/protein kinase B) in activated microglia. In EAE, axonal injury correlated with accumulation of microglia/macrophages in the spinal cord. EAE mice treated with laquinimod before onset of clinical signs subsequently had reduced microglia/macrophage density and axonal injury. Remarkably, when laquinimod treatment was initiated well into the disease course, the progressive demyelination, and axonal loss was halted. Besides inflammatory molecules associated with microglia, the level of inducible nitric oxide (NO) synthase capable of producing free radical toxicity was attenuated by laquinimod in EAE mice. Finally, in coculture where microglia activation caused neuronal death, laquinimod decreased NO levels, and neurotoxicity.
Interpretation
Laquinimod is a novel inhibitor of microglial activation that lowers microglia-induced neuronal death in culture and axonal injury/loss in EAE.
doi:10.1002/acn3.67
PMCID: PMC4184669  PMID: 25356411
12.  Neuroprotective intervention by interferon-γ blockade prevents CD8+ T cell–mediated dendrite and synapse loss 
The Journal of Experimental Medicine  2013;210(10):2087-2103.
IFN-γ produced by CD8+ cytotoxic T cells acts on neurons to induce Stat1-associated loss of dendrites and synapses in a mouse model of viral encephalitis.
Neurons are postmitotic and thus irreplaceable cells of the central nervous system (CNS). Accordingly, CNS inflammation with resulting neuronal damage can have devastating consequences. We investigated molecular mediators and structural consequences of CD8+ T lymphocyte (CTL) attack on neurons in vivo. In a viral encephalitis model in mice, disease depended on CTL-derived interferon-γ (IFN-γ) and neuronal IFN-γ signaling. Downstream STAT1 phosphorylation and nuclear translocation in neurons were associated with dendrite and synapse loss (deafferentation). Analogous molecular and structural alterations were also found in human Rasmussen encephalitis, a CTL-mediated human autoimmune disorder of the CNS. Importantly, therapeutic intervention by IFN-γ blocking antibody prevented neuronal deafferentation and clinical disease without reducing CTL responses or CNS infiltration. These findings identify neuronal IFN-γ signaling as a novel target for neuroprotective interventions in CTL-mediated CNS disease.
doi:10.1084/jem.20122143
PMCID: PMC3782053  PMID: 23999498
13.  Oligodendroglia in cortical multiple sclerosis lesions decrease with disease progression, but regenerate after repeated experimental demyelination 
Acta Neuropathologica  2014;128(2):231-246.
Cerebral cortex shows a high endogenous propensity for remyelination. Yet, widespread subpial cortical demyelination (SCD) is a common feature in progressive multiple sclerosis (MS) and can already be found in early MS. In the present study, we compared oligodendroglial loss in SCD in early and chronic MS. Furthermore, we addressed in an experimental model whether repeated episodes of inflammatory SCD could alter oligodendroglial repopulation and subsequently lead to persistently demyelinated cortical lesions. NogoA+ mature oligodendrocytes and Olig2+ oligodendrocyte precursor cells were examined in SCD in patients with early and chronic MS, normal-appearing MS cortex, and control cortex as well as in the rat model of repeated targeted cortical experimental autoimmune encephalomyelitis (EAE). NogoA+ and Olig2+ cells were significantly reduced in SCD in patients with chronic, but not early MS. Repeated induction of SCD in rats resulted only in a transient loss of NogoA+, but not Olig2+ cells during the demyelination phase. This phase was followed by complete oligodendroglial repopulation and remyelination, even after four episodes of demyelination. Our data indicate efficient oligodendroglial repopulation in subpial cortical lesions in rats after repeated SCD that was similar to early, but not chronic MS cases. Accordingly, four cycles of experimental de- and remyelination were not sufficient to induce sustained remyelination failure as found in chronic cortical MS lesions. This suggests that alternative mechanisms contribute to oligodendrocyte depletion in chronic cortical demyelination in MS.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-014-1260-8) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-014-1260-8
PMCID: PMC4102825  PMID: 24563023
Multiple sclerosis; Cortical demyelination; Oligodendrocytes; Oligodendrocyte precursors; Targeted cortical EAE
14.  Limited TCF7L2 Expression in MS Lesions 
PLoS ONE  2013;8(8):e72822.
Multiple sclerosis is the most frequent demyelinating disease in the human CNS characterized by inflammation, demyelination, relative axonal loss and gliosis. Remyelination occurs, but is frequently absent or restricted to a small remyelinated rim at the lesion border. Impaired differentiation of oligodendroglial precursor cells is one factor contributing to limited remyelination, especially in chronic MS. TCF7L2 is an oligodendroglial transcription factor regulating myelin gene expression during developmental myelination as well as remyelination. TCF7L2 binds to co-effectors such as β-catenin or histone deacetylases and thereby activates or inhibits the transcription of downstream genes involved in oligodendroglial differentiation. To determine whether TCF7L2 can be used as a marker for differentiating or myelinating oligodendrocytes, we analyzed the expression patterns of TCF7L2 during myelination and remyelination in human and murine CNS tissue samples. Here, we demonstrate that marked expression of TCF7L2 in oligodendrocytes is restricted to a well defined time period during developmental myelination in human and mouse CNS tissue samples. In demyelinating diseases, such as multiple sclerosis, TCF7L2 is reexpressed in oligodendrocytes in a subset of MS patients, but is also present in tissue samples from patients with non-demyelinating, inflammatory diseases. Furthermore, TCF7L2 expression was also detected in astrocytes. HDAC2, a potential binding partner of TCF7L2 that promotes oligodendroglial differentiation and myelination, is expressed in the majority of oligodendrocytes in controls and MS tissue samples. In summary, our data demonstrate that the expression of TCF7L2 in oligodendrocytes is limited to a certain differentiation stage; however the expression of TCF7L2 is neither restricted to the oligodendroglial lineage nor to (re-)myelinating conditions.
doi:10.1371/journal.pone.0072822
PMCID: PMC3748032  PMID: 23977356
15.  Bacterial Cytolysin during Meningitis Disrupts the Regulation of Glutamate in the Brain, Leading to Synaptic Damage 
PLoS Pathogens  2013;9(6):e1003380.
Streptococcus pneumoniae (pneumococcal) meningitis is a common bacterial infection of the brain. The cholesterol-dependent cytolysin pneumolysin represents a key factor, determining the neuropathogenic potential of the pneumococci. Here, we demonstrate selective synaptic loss within the superficial layers of the frontal neocortex of post-mortem brain samples from individuals with pneumococcal meningitis. A similar effect was observed in mice with pneumococcal meningitis only when the bacteria expressed the pore-forming cholesterol-dependent cytolysin pneumolysin. Exposure of acute mouse brain slices to only pore-competent pneumolysin at disease-relevant, non-lytic concentrations caused permanent dendritic swelling, dendritic spine elimination and synaptic loss. The NMDA glutamate receptor antagonists MK801 and D-AP5 reduced this pathology. Pneumolysin increased glutamate levels within the mouse brain slices. In mouse astrocytes, pneumolysin initiated the release of glutamate in a calcium-dependent manner. We propose that pneumolysin plays a significant synapto- and dendritotoxic role in pneumococcal meningitis by initiating glutamate release from astrocytes, leading to subsequent glutamate-dependent synaptic damage. We outline for the first time the occurrence of synaptic pathology in pneumococcal meningitis and demonstrate that a bacterial cytolysin can dysregulate the control of glutamate in the brain, inducing excitotoxic damage.
Author Summary
Bacterial meningitis is one of the most devastating brain diseases. Among the bacteria that cause meningitis, Streptococcus pneumoniae is the most common. Meningitis predominantly affects children, especially in the Third World, and most of them do not survive. Those that do survive often suffer permanent brain damage and hearing problems. The exact morphological substrates of brain damage in Streptococcus pneumoniae meningitis remain largely unknown. In our experiments, we found that the brain cortex of patients with meningitis demonstrated a loss of synapses (the contact points among neurons, responsible for the processes of learning and memory), and we identified the major pneumococcal neurotoxin pneumolysin as a sufficient cause of this loss. The effect was not direct but was mediated by the brain neurotransmitter glutamate, which was released upon toxin binding by one of the non-neuronal cell types of the brain – the astrocytes. Pneumolysin initiated calcium influx in astrocytes and subsequent glutamate release. Glutamate damaged the synapses via NMDA-receptors – a mechanism similar to the damage occurring in brain ischemia. Thus, we show that synaptic loss is present in pneumococcal meningitis, and we identify the toxic bacterial protein pneumolysin as the major factor in this process. These findings alter our understanding of bacterial meningitis and establish new therapeutic strategies for this fatal disease.
doi:10.1371/journal.ppat.1003380
PMCID: PMC3681734  PMID: 23785278
16.  Microglial nodules in early multiple sclerosis white matter are associated with degenerating axons 
Acta Neuropathologica  2013;125(4):595-608.
Microglial nodules in the normal-appearing white matter have been suggested as the earliest stage(s) of multiple sclerosis (MS) lesion formation. Such nodules are characterized by an absence of leukocyte infiltration, astrogliosis or demyelination, and may develop into active demyelinating MS lesions. Although the etiology of MS is still not known, inflammation and autoimmunity are considered to be the central components of this disease. Previous studies provide evidence that Wallerian degeneration, occurring as a consequence of structural damage in MS lesions, might be responsible for observed pathological abnormalities in connected normal-appearing white matter. As innate immune cells, microglia/macrophages are the first to react to even minor pathological changes in the CNS. Biopsy tissue from 27 MS patients and autopsy and biopsy tissue from 22 normal and pathological controls were analyzed to determine the incidence of microglial nodules. We assessed MS periplaque white matter tissue from early disease stages to determine whether microglial nodules are associated with altered axons. With immunohistochemical methods, the spatial relation of the two phenomena was visualized using HLA-DR antibody for MHC II expression by activated microglia/macrophages and by applying antibodies against damaged axons, i.e., SMI32 (non-phosphorylated neurofilaments) and amyloid precursor protein as well as neuropeptide Y receptor Y1, which marks axons undergoing Wallerian degeneration. Our data demonstrate that the occurrence of microglial nodules is not specific to MS and is associated with degenerating as well as damaged axons in early MS. In addition, we show that early MS microglial nodules exhibit both pro- and antiinflammatory phenotypes.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-013-1082-0) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-013-1082-0
PMCID: PMC3611040  PMID: 23354834
Wallerian degeneration; Microglial nodules; Multiple sclerosis; Preactive lesions; Axonal damage; Microglia activation
17.  Reduced astrocytic NF-κB activation by laquinimod protects from cuprizone-induced demyelination 
Acta Neuropathologica  2012;124(3):411-424.
Laquinimod (LAQ) is a new oral immunomodulatory compound that reduces relapse rate, brain atrophy and disability progression in multiple sclerosis (MS). LAQ has well-documented effects on inflammation in the periphery, but little is known about its direct activity within the central nervous system (CNS). To elucidate the impact of LAQ on CNS-intrinsic inflammation, we investigated the effects of LAQ on cuprizone-induced demyelination in mice in vivo and on primary CNS cells in vitro. Demyelination, inflammation, axonal damage and glial pathology were evaluated in LAQ-treated wild type and Rag-1-deficient mice after cuprizone challenge. Using primary cells we tested for effects of LAQ on oligodendroglial survival as well as on cytokine secretion and NF-κB activation in astrocytes and microglia. LAQ prevented cuprizone-induced demyelination, microglial activation, axonal transections, reactive gliosis and oligodendroglial apoptoses in wild type and Rag-1-deficient mice. LAQ significantly decreased pro-inflammatory factors in stimulated astrocytes, but not in microglia. Oligodendroglial survival was not affected by LAQ in vitro. Astrocytic, but not microglial, NF-κB activation was markedly reduced by LAQ as evidenced by NF-κB reporter assay. LAQ also significantly decreased astrocytic NF-κB activation in cuprizone-treated mice. Our data indicate that LAQ prevents cuprizone-induced demyelination by attenuating astrocytic NF-κB activation. These effects are CNS-intrinsic and not mediated by peripheral immune cells. Therefore, LAQ downregulation of the astrocytic pro-inflammatory response may be an important mechanism underlying its protective effects on myelin, oligodendrocytes and axons. Modulation of astrocyte activation may be an attractive therapeutic target to prevent tissue damage in MS.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-012-1009-1) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-012-1009-1
PMCID: PMC3422618  PMID: 22766690
Demyelination; Laquinimod; Cuprizone; Astrocytes; NF-κB; Multiple sclerosis
18.  Inflammatory Cortical Demyelination in Early Multiple Sclerosis 
The New England Journal of Medicine  2011;365(23):2188-2197.
BACKGROUND
Cortical disease has emerged as a critical aspect of the pathogenesis of multiple sclerosis, being associated with disease progression and cognitive impairment. Most studies of cortical lesions have focused on autopsy findings in patients with long-standing, chronic, progressive multiple sclerosis, and the noninflammatory nature of these lesions has been emphasized. Magnetic resonance imaging studies indicate that cortical damage occurs early in the disease.
METHODS
We evaluated the prevalence and character of demyelinating cortical lesions in patients with multiple sclerosis. Cortical tissues were obtained in passing during biopsy sampling of white-matter lesions. In most cases, biopsy was done with the use of stereotactic procedures to diagnose suspected tumors. Patients with sufficient cortex (138 of 563 patients screened) were evaluated for cortical demyelination. Using immunohistochemistry, we characterized cortical lesions with respect to demyelinating activity, inflammatory infiltrates, the presence of meningeal inflammation, and a topographic association between cortical demyelination and meningeal inflammation. Diagnoses were ascertained in a subgroup of 77 patients (56%) at the last follow-up visit (at a median of 3.5 years).
RESULTS
Cortical demyelination was present in 53 patients (38%) (104 lesions and 222 tissue blocks) and was absent in 85 patients (121 tissue blocks). Twenty-five patients with cortical demyelination had definite multiple sclerosis (81% of 31 patients who underwent long-term follow-up), as did 33 patients without cortical demyelination (72% of 46 patients who underwent long-term follow-up). In representative tissues, 58 of 71 lesions (82%) showed CD3+ T-cell infiltrates, and 32 of 78 lesions (41%) showed macrophage-associated demyelination. Meningeal inflammation was topographically associated with cortical demyelination in patients who had sufficient meningeal tissue for study.
CONCLUSIONS
In this cohort of patients with early-stage multiple sclerosis, cortical demyelinating lesions were frequent, inflammatory, and strongly associated with meningeal inflammation. (Funded by the National Multiple Sclerosis Society and the National Institutes of Health.)
doi:10.1056/NEJMoa1100648
PMCID: PMC3282172  PMID: 22150037
19.  Related B cell clones that populate the CSF and CNS of patients with multiple sclerosis produce CSF immunoglobulin 
Journal of neuroimmunology  2011;233(1-2):245-248.
We investigated the overlap shared between the immunoglobulin (Ig) proteome of the cerebrospinal fluid (CSF) and the B cell Ig-transcriptome of CSF and the central nervous system (CNS) tissue of three patients with multiple sclerosis. We determined the IgG-proteomes of CSF by mass spectrometry, and compared them to the IgG-transcriptomes from CSF and brain lesions, which were analyzed by cDNA cloning. Characteristic peptides that were identified in the CSF-proteome could also be detected in the transcriptomes of both, brain lesions and CSF, providing evidence for a strong overlap of the IgG repertoires in brain lesions and in the CSF.
doi:10.1016/j.jneuroim.2011.01.010
PMCID: PMC3090654  PMID: 21353315
multiple sclerosis; B cells; cerebrospinal fluid; central nervous system; oligoclonal bands
20.  IκB kinase 2 determines oligodendrocyte loss by non-cell-autonomous activation of NF-κB in the central nervous system 
Brain  2011;134(4):1184-1198.
The IκB kinase complex induces nuclear factor kappa B activation and has recently been recognized as a key player of autoimmunity in the central nervous system. Notably, IκB kinase/nuclear factor kappa B signalling regulates peripheral myelin formation by Schwann cells, however, its role in myelin formation in the central nervous system during health and disease is largely unknown. Surprisingly, we found that brain-specific IκB kinase 2 expression is dispensable for proper myelin assembly and repair in the central nervous system, but instead plays a fundamental role for the loss of myelin in the cuprizone model. During toxic demyelination, inhibition of nuclear factor kappa B activation by conditional ablation of IκB kinase 2 resulted in strong preservation of central nervous system myelin, reduced expression of proinflammatory mediators and a significantly attenuated glial response. Importantly, IκB kinase 2 depletion in astrocytes, but not in oligodendrocytes, was sufficient to protect mice from myelin loss. Our results reveal a crucial role of glial cell-specific IκB kinase 2/nuclear factor kappa B signalling for oligodendrocyte damage during toxic demyelination. Thus, therapies targeting IκB kinase 2 function in non-neuronal cells may represent a promising strategy for the treatment of distinct demyelinating central nervous system diseases.
doi:10.1093/brain/awq359
PMCID: PMC4055835  PMID: 21310728
oligodendrocyte; demyelination; remyelination; NF-κB; glia; cuprizone; multiple sclerosis
21.  Effects of pulmonary acid aspiration on the lungs and extra-pulmonary organs: a randomized study in pigs 
Critical Care  2012;16(2):R35.
Introduction
There is mounting evidence that injury to one organ causes indirect damage to other organ systems with increased morbidity and mortality. The aim of this study was to determine the effects of acid aspiration pneumonitis (AAP) on extrapulmonary organs and to test the hypothesis that these could be due to circulatory depression or hypoxemia.
Methods
Mechanically ventilated anesthetized pigs were randomized to receive intrabronchial instillation of hydrochloric acid (n = 7) or no treatment (n = 7). Hydrochloric acid (0.1 N, pH 1.1, 2.5 ml/kg BW) was instilled into the lungs during the inspiratory phase of ventilation. Hemodynamics, respiratory function and computer tomography (CT) scans of lung and brain were followed over a four-hour period. Tissue samples of lung, heart, liver, kidney and hippocampus were collected at the end of the experiment.
Results
Acid instillation caused pulmonary edema, measured as increased extravascular lung water index (ELWI), impaired gas exchange and increased mean pulmonary artery pressure. Gas exchange tended to improve during the course of the study, despite increasing ELWI. In AAP animals compared to controls we found: a) cardiac leukocyte infiltration and necrosis in the conduction system and myocardium; b) lymphocyte infiltration in the liver, spreading from the periportal zone with prominent areas of necrosis; c) renal inflammation with lymphocyte infiltration, edema and necrosis in the proximal and distal tubules; and d) a tendency towards more severe hippocampal damage (P > 0.05).
Conclusions
Acid aspiration pneumonitis induces extrapulmonary organ injury. Circulatory depression and hypoxemia are unlikely causative factors. ELWI is a sensitive bedside parameter of early lung damage.
doi:10.1186/cc11214
PMCID: PMC3681347  PMID: 22380702
22.  Pathology of immune reconstitution inflammatory syndrome in multiple sclerosis with natalizumab-associated progressive multifocal leukoencephalopathy 
Acta Neuropathologica  2011;123(2):235-245.
Natalizumab is an approved medication for highly active multiple sclerosis (MS). Progressive multifocal leukoencephalopathy (PML) may occur as a severe side effect of this drug. Here, we describe pathological and radiological characteristics of immune reconstitution inflammatory syndrome (IRIS), which occurs in natalizumab-associated PML after the cessation of therapy, and we differentiate it from ongoing PML. Brain biopsy tissue and MRI scans from five MS patients with natalizumab-associated PML were analyzed and their histology compared with non-MS PML. Histology showed an extensive CD8-dominated T cell infiltrate and numerous macrophages within lesions, and in nondemyelinated white and grey matter, in four out of five cases. Few or no virally infected cells were found. This was indicative of IRIS as known from HIV patients with PML. Outstandingly high numbers of plasma cells were present as compared to non-MS PML and typical MS lesions. MRI was compatible with IRIS, revealing enlarging lesions with a band-like or speckled contrast enhancement either at the lesion edge or within lesions. Only the fifth patient showed typical PML pathology, with low inflammation and high numbers of virally infected cells. This patient showed a similar interval between drug withdrawal and biopsy (3.5 months) to the rest of the cohort (range 2.5–4 months). MRI could not differentiate between PML-associated IRIS and ongoing PML. We describe in detail the histopathology of IRIS in natalizumab-associated PML. PML–IRIS, ongoing PML infection, and MS exacerbation may be impossible to discern clinically alone. MRI may provide some clues for distinguishing different pathologies that can be differentiated histologically. In our individual cases, biopsy helped to clarify diagnoses in natalizumab-associated PML.
doi:10.1007/s00401-011-0900-5
PMCID: PMC3259335  PMID: 22057786
IRIS; Natalizumab; PML; MS; Pathology; MRI
23.  Acute effects of intracranial hypertension and ARDS on pulmonary and neuronal damage: a randomized experimental study in pigs 
Intensive Care Medicine  2011;37(7):1182-1191.
Purpose
To determine reciprocal and synergistic effects of acute intracranial hypertension and ARDS on neuronal and pulmonary damage and to define possible mechanisms.
Methods
Twenty-eight mechanically ventilated pigs were randomized to four groups of seven each: control; acute intracranial hypertension (AICH); acute respiratory distress syndrome (ARDS); acute respiratory distress syndrome in combination with acute intracranial hypertension (ARDS + AICH). AICH was induced with an intracranial balloon catheter and the inflation volume was adjusted to keep intracranial pressure (ICP) at 30–40 cmH2O. ARDS was induced by oleic acid infusion. Respiratory function, hemodynamics, extravascular lung water index (ELWI), lung and brain computed tomography (CT) scans, as well as inflammatory mediators, S100B, and neuronal serum enolase (NSE) were measured over a 4-h period. Lung and brain tissue were collected and examined at the end of the experiment.
Results
In both healthy and injured lungs, AICH caused increases in NSE and TNF-alpha plasma concentrations, extravascular lung water, and lung density in CT, the extent of poorly aerated (dystelectatic) and atelectatic lung regions, and an increase in the brain tissue water content. ARDS and AICH in combination induced damage in the hippocampus and decreased density in brain CT.
Conclusions
AICH induces lung injury and also exacerbates pre-existing damage. Increased extravascular lung water is an early marker. ARDS has a detrimental effect on the brain and acts synergistically with intracranial hypertension to cause histological hippocampal damage.
Electronic supplementary material
The online version of this article (doi:10.1007/s00134-011-2232-2) contains supplementary material, which is available to authorized users.
doi:10.1007/s00134-011-2232-2
PMCID: PMC3127009  PMID: 21544692
ABI; ARDS; ELWI; CT scan; Organ dysfunction
24.  Necrotizing infundibulo-hypophysitis: an entity too rare to be true? 
Pituitary  2011;15(2):202-208.
We report a young woman with sudden and severe retroorbital headache, neck pain, and a large sellar mass extending to the suprasellar cistern. A presumptive diagnosis of non-secreting pituitary macroadenoma undergoing apoplexy was made and transphenoidal surgery performed. Histopathology revealed mononuclear infiltration and marked non-hemorrhagic necrosis of the anterior pituitary consistent with a diagnosis of necrotizing infundibulo-hypophysitis. The possible pathogenesis of this rare variant of hypophysitis is discussed.
doi:10.1007/s11102-011-0307-2
PMCID: PMC3358537  PMID: 21479815
Hypophysitis; Necrosis; Pituitary infarction
25.  Intracerebral Human Regulatory T Cells: Analysis of CD4+CD25+FOXP3+ T Cells in Brain Lesions and Cerebrospinal Fluid of Multiple Sclerosis Patients 
PLoS ONE  2011;6(3):e17988.
Impaired suppressive capacity of CD4+CD25+FOXP3+ regulatory T cells (Treg) from peripheral blood of patients with multiple sclerosis (MS) has been reported by multiple laboratories. It is, however, currently unresolved whether Treg dysfunction in MS patients is limited to reduced control of peripheral T cell activation since most studies analyzed peripheral blood samples only. Here, we assessed early active MS lesions in brain biopsies obtained from 16 patients with MS by FOXP3 immunohistochemistry. In addition, we used six-color flow cytometry to determine numbers of Treg by analysis of FOXP3/CD127 expression in peripheral blood and cerebrospinal fluid (CSF) of 17 treatment-naïve MS patients as well as quantities of apoptosis sensitive CD45ROhiCD95hi cells in circulating and CSF Treg subsets. Absolute numbers of FOXP3+ and CD4+ cells were rather low in MS brain lesions and Treg were not detectable in 30% of MS biopsies despite the presence of CD4+ cell infiltrates. In contrast, Treg were detectable in all CSF samples and Treg with a CD45ROhiCD95hi phenotype previously shown to be highly apoptosis sensitive were found to be enriched in the CSF compared to peripheral blood of MS patients. We suggest a hypothetical model of intracerebral elimination of Treg by CD95L-mediated apoptosis within the MS lesion.
doi:10.1371/journal.pone.0017988
PMCID: PMC3060879  PMID: 21437244

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