Neuropathology of multiple sclerosis-new concepts

The release of cytokines by macrophages is not affected by myelin ingestion

Macrophages play an important role in demyelination in multiple sclerosis (MS). Activated macrophages ingest myelin particles, thereby acquiring a foamy appearance. Foamy macrophages in MS lesions were described as being anti-inflammatory. Therefore, these cells might play a role in modulating the inflammatory state of an active lesion. Here, we investigated the mechanism by which myelin uptake leads to skewing of macrophages toward an anti-inflammatory phenotype. Macrophages were incubated with myelin, leading to the development of foamy macrophages. Afterwards, the cells were stimulated with the TLR-4 ligand lipopolysaccharide (LPS), and cytokine production was determined. Interestingly, foamy macrophages appeared to have a reduced cytokine secretion and were LPS insensitive only when generated with one of the myelin preparations. The factor responsible for the different outcomes between different myelin batches turned out to be LPS. We demonstrated that LPS contamination induced insensitivity to LPS in foamy macrophages. On the contrary, foamy macrophages generated in the presence of LPS-free myelin were able to secrete cytokines upon activation. To conclude, myelin-laden macrophages were not LPS insensitive, indicating that they had not acquired an anti-inflammatory phenotype.

Fibrinogen depleting agent batroxobin has a beneficial effect on experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) was characterized with widespread demyelination and axonal loss of central nervous system (CNS). Fibrinogen (fibrin) deposition was considered as one of the pathogenesis of MS. Therefore, we explored the effects of fibrinogen depleting agent batroxobin in experimental autoimmune encephalomyelitis (EAE) mice model. Our study showed that prevention and suppression with batroxobin significantly ameliorated clinical severity of EAE, reduced inflammatory cells infiltration, and demyelination, and suppressed the activation of astrocytes and macrophages comprising the CD11b(+) population. Batroxobin treatment leads to reduced expression of p-Akt and increased expression of MBP as compared to control. In addition, batroxobin treatment partly reversed the dendric-like formation of macrophages irritated by fibrinogen in vitro. The reduced severity of EAE mice treated with batroxobin suggests that strategy targeting fibrin as a potential therapy for EAE may be beneficial for the treatment of MS patients.

The role of infections in the pathogenesis and course of multiple sclerosis

Interplay between susceptibility genes and environmental factors is considered important player in the genesis of multiple sclerosis (MS). Among environmental factors, a role for an infectious pathogen has long been considered central to the disease process. This opinion has support both from epidemiological data and the findings of immunological abnormalities in spinal fluid that reflect an immune response to an as yet undetermined antigen, possibly a pathogen, in the cerebrospinal fluid. Our review will outline the current understanding of the role of infection in the causation and progression of MS. We will review the data that point to an infectious cause of MS and consider the specific agents Chlamydophila (Chlamydia) pneumoniae, Human Herpes Virus 6, and Epstein-Barr Virus, that are implicated in either the development or progression of MS.

An animal model of cortical and callosal pathology in multiple sclerosis

The pathological and radiological hallmarks of multiple sclerosis (MS) include multiple demyelinated lesions disseminated throughout the white matter of the central nervous system (CNS). More recently, the cerebral cortex has been shown to be affected in MS, but the elucidation of events causing cortical demyelination has been hampered by the lack of animal models reflecting such human cortical pathology. In this report, we have described the presence of cortical gray matter and callosal white matter demyelinating lesions in the chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Similar to the pathological lesions of MS patients, EAE lesions have been classified as type I-leukocortical, type II-intracortical and type III-subpial. All of these lesions had varying degrees of demyelination, inflammatory cells and reactive astrocytes. Similar to MS, cortical layers during EAE showed demyelination, microglia activation, synaptic protein alterations and apoptotic cells. In addition, the callosal white matter during EAE had many inflammatory demyelinating lesions and axon degeneration. Functional electrophysiological conduction analysis showed deficits in both myelinated and unmyelinated callosal axons during early and late EAE. The chronic EAE mouse model has features that mimic cortical and callosal pathology of MS, and can be potentially used to screen agents to prevent these features of disease.

Appearance of tissue transglutaminase in astrocytes in multiple sclerosis lesions: a role in cell adhesion and migration?

Multiple Sclerosis (MS) is a neuroinflammatory disease mainly affecting young adults. A major pathological hallmark of MS is the presence of demyelinated lesions in the central nervous system. In the active phase of the disease, astrocytes become activated, migrate and contribute to local tissue remodeling that ultimately can result in an astroglial scar. This process is facilitated by extracellular matrix proteins, including fibronectin. Tissue Transglutaminase (TG2) is a multifunctional enzyme with a ubiquitous tissue distribution and it has been shown that inflammatory cytokines can induce TG2 activity. In addition, TG2 is known to mediate cell adhesion and migration. We therefore hypothesized that TG2 is present in MS lesions and plays a role in cell adhesion and/or migration. Our studies showed that TG2 immunoreactivity appeared in astrocytes in active and chronic active MS lesions. These TG2 positive astrocytes partly co-localized with fibronectin. Additional in vitro studies showed that TG2 mediated astrocytoma adhesion to and migration on the extracellular matrix protein fibronectin. We therefore speculate that TG2 mediates the enhanced interaction of astrocytes with fibronectin in the extracellular matrix of MS lesions, thereby contributing to astrocyte adhesion and migration, and thus in tissue remodeling and possibly glial scarring.

HERVs in neuropathogenesis

In humans, exogenous retroviruses are known to cause immunodeficiency and neurological disease. While endogenous retroviruses are firmly established pathogens in other species, the human endogenous retroviruses (HERVs) may well be considered as emerging pathogens. HERVs also exhibit complex interactions with exogenous retroviruses and herpesviruses. Two neurological disorders in particular are associated with HERVs: multiple sclerosis (MS) and schizophrenia. HERV-H/F and HERV-W are specifically activated both in the circulation and the central nervous system (CNS) in a majority of MS patients, and particularly, the envelopes (env transcription and Env proteins) appear strongly associated with disease activity. Interferon beta (IFN-beta) therapy is well-established for MS. IFN-beta is also known to have anti-retroviral activities toward exogenous retroviruses (HIV and HTLV-I). New reports show that IFN-beta also mediate down-regulation of HERV-H/F and HERV-W in MS patients. HERV-W and HERV-K transcription (gag and pol) appears, to some extent, to be up-regulated in the circulation and the CNS of patients with schizophrenia. The expression of anti-HERV-W Gag reactive epitopes is reported to be down-regulated in the brain but up-regulated in the blood from schizophrenia patients. The pathogenic potential of HERVs certainly merits further studies.

Fingolimod (FTY720) enhances remyelination following demyelination of organotypic cerebellar slices

Remyelination, which occurs subsequent to demyelination, contributes to functional recovery and is mediated by oligodendrocyte progenitor cells (OPCs) that have differentiated into myelinating cells. Therapeutics that impact remyelination in the CNS could be critical determinants of long-term functional outcome in multiple sclerosis (MS). Fingolimod is a S1P receptor modulator in MS clinical trials due to systemic anti-inflammatory properties, yet may impact cells within the CNS by crossing the blood-brain barrier. Previous studies using isolated dissociated cultures indicate that neural cells express S1P receptors and respond to receptor engagement. Our objective was to assess the effects of fingolimod on myelin-related processes within a multicellular environment that maintains physiological cell-cell interactions, using organotypic cerebellar slice cultures. Fingolimod treatment had no impact on myelin under basal conditions. Fingolimod treatment subsequent to lysolecithin-induced demyelination enhanced remyelination and process extension by OPCs and mature oligodendrocytes, while increasing microglia numbers and immunoreactivity for the astrocytic marker glial fibrillary acidic protein. The number of phagocytosing microglia was not increased by fingolimod. Using S1P receptor specific agonists and antagonists, we determined that fingolimod-induced effects on remyelination and astrogliosis were mediated primarily through S1P3 and S1P5, whereas enhanced microgliosis was mediated through S1P1 and S1P5. Taken together, these data demonstrate that fingolimod modulates multiple neuroglial cell responses, resulting in enhanced remyelination in organotypic slice cultures that maintain the complex cellular interactions of the mammalian brain.

Central neuroinvasion and demyelination by inflammatory macrophages after peripheral virus infection is controlled by SHP-1

SHP-1 is a protein tyrosine phosphatase that negatively regulates cytokine signaling and inflammatory gene expression. Mice genetically lacking SHP-1 (me/me) display severe inflammatory demyelinating disease following intracranial inoculation with the BeAn strain of Theiler's murine encephalomyelitis virus (TMEV) compared to infected wild-type mice. Furthermore, SHP-1-deficient mice show a profound and predominant infiltration of blood-derived macrophages into the CNS following intracerebral injection of TMEV, and these macrophages are concentrated in areas of demyelination in brain and spinal cord. In the present study we investigated the role of SHP-1 in controlling CNS inflammatory demyelination following a peripheral instead of an intracerebral inoculation of TMEV. Surprisingly, we found that while wild-type mice were entirely refractory to intraperitoneal (IP) infection by TMEV, in agreement with previous studies, all SHP-1-deficient mice displayed profound macrophage neuroinvasion and macrophage-mediated inflammatory demyelination. Moreover, SHP-1 deficiency led to increased expression of inflammatory molecules in macrophages, serum, and CNS following IP infection with TMEV. Importantly, pharmacological depletion of peripheral macrophages significantly decreased both paralysis and CNS viral loads in SHP-1-deficient mice. In addition, peripheral MCP-1 neutralization attenuated disease severity, decreased macrophage infiltration into the CNS, and decreased monocyte numbers in the blood of SHP-1-deficient mice, implicating MCP-1 as an important mediator of monocyte migration between multiple tissues. These results demonstrate that peripheral TMEV infection results in a unique evolution of macrophage-mediated demyelination in SHP-1-deficient mice, implicating SHP-1 in the control of neuroinvasion of inflammatory macrophages and neurotropic viruses into the CNS.

Lentiviral vector-mediated gene transfer and RNA silencing technology in neuronal dysfunctions

Lentiviral-mediated gene transfer in vivo or in cultured mammalian neurons can be used to address a wide variety of biological questions, to design animal models for specific neurodegenerative pathologies, or to test potential therapeutic approaches in a variety of brain disorders. Lentiviruses can infect nondividing cells, thereby allowing stable gene transfer in postmitotic cells such as mature neurons. An important contribution has been the use of inducible vectors: the same animal can thus be used repeatedly in the doxycycline-on or -off state, providing a powerful mean for assessing the function of a gene candidate in a disorder within a specific neuronal circuit. Furthermore, lentivirus vectors provide a unique tool to integrate siRNA expression constructs with the aim to locally knockdown expression of a specific gene, enabling to assess the function of a gene in a very specific neuronal pathway. Lentiviral vector-mediated delivery of short hairpin RNA results in persistent knockdown of gene expression in the brain. Therefore, the use of lentiviruses for stable expression of siRNA in brain is a powerful aid to probe gene functions in vivo and for gene therapy of diseases of the central nervous system. In this chapter, I review the applications of lentivirus-mediated gene transfer in the investigation of specific gene candidates involved in major brain disorders and neurodegenerative processes. Major applications have been in polyglutamine disorders, such as synucleinopathies and Parkinson's disease, or in investigating gene function in Huntington's disease, dystonia, or muscular dystrophy. Recently, lentivirus gene transfer has been an invaluable tool for evaluation of gene function in behavioral disorders such as drug addiction and attention-deficit hyperactivity disorder or in learning and cognition.

Multiple sclerosis: an update for oral health care providers

Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the central nervous system. The disease mostly affects young adults and is increasing in prevalence and incidence. Multiple sclerosis is characterized by periods of activity and remission which, after numerous relapses, cause permanent neurologic deficits. Diagnosis of MS is based on patient history and clinical examination supplemented by the findings of radiologic and laboratory tests. Numerous motor and sensory disturbances occur in MS and may present in the orofacial region. This medical management update highlights issues that are important to the oral health care provider, including orofacial manifestations of MS and dental considerations for patients with MS.

Meningeal inflammation is not associated with cortical demyelination in chronic multiple sclerosis

Cortical demyelination can be extensive in chronic multiple sclerosis (MS) patients. Cortical lesions are not associated with lymphocyte infiltration, blood-brain barrier disruption, or complement deposition; therefore, their pathogenesis is unclear. We analyzed the extent and cellular composition of leptomeningeal inflammatory infiltrates and their relationship with cortical demyelinated lesions in brain autopsy samples from 28 chronic MS patients; samples from 6 nonneurological disease control patients were also studied. Immunohistochemistry was used to detect meningeal T cells, B cells, macrophages, mature and immature dendritic cells, T-helper cells, (activated) cytotoxic T cells, and plasma cells. Quantitative analysis revealed significant meningeal inflammation in chronic MS patients; T cells were the predominant inflammatory cells. Morphometric analysis was performed on coronal hemisphere sections of the MS cases to assess subpial demyelination; no correlation between the extent of subpial demyelination and extent of meningeal inflammation was identified. Moreover, no differences were observed in the degree or cellular composition of meningeal infiltrates in areas directly adjacent to subpial lesions compared with areas adjacent to normal-appearing gray matter in the MS cases. In addition, no follicle-like structures were found in the MS samples. Our data suggest that the occurrence of cortical lesions is not related to the presence of meningeal inflammation in a large number of chronic MS patients.

Effects of interferon-beta therapy on innate and adaptive immune responses to the human endogenous retroviruses HERV-H and HERV-W, cytokine production, and the lectin complement activation pathway in multiple sclerosis

The effects of treatment of multiple sclerosis patients with IFN-beta on elements in the innate and adaptive immune response were analysed in a longitudinal study. We demonstrate significant decreases in anti-Envelope antibody reactivity for the two closely related Gammaretroviral human endogenous retroviruses (HERVs), HERV-H and HERV-W, as a consequence of IFN-beta therapy, closely linked to efficacy of therapy/low disease activity. We also show strong indications of a protective effect of high levels of two components in the innate pathogen-associated molecular pattern recognition: mannan-binding lectin (MBL), and MBL-associated serine protease 3 (MASP-3). Serum levels of typical Th1- and Th2-related, MS-relevant cytokines were also monitored. Overall both Th1- and Th2-associated cytokines were modestly, albeit significantly up-regulated, notably IL-2 and TNF-alpha (MS patients with inactive disease), as well as IL-4 and, to some extent IL-10 (no increase in IL-10 for MS patients with active disease (non-responders)). We found no overall changes in Th1/Th2 ratios. Our results support that HERV-H/HERV-W and the antiviral immune response may play a role in MS development, and that these HERVs have potential as biomarkers for disease activity.

Degradation of amyloid beta protein by purified myelin basic protein

The progressive accumulation of beta-amyloid (Abeta) in senile plaques and in the cerebral vasculature is the hallmark of Alzheimer disease and related disorders. Impaired clearance of Abeta from the brain likely contributes to the prevalent sporadic form of Alzheimer disease. Several major pathways for Abeta clearance include receptor-mediated cellular uptake, blood-brain barrier transport, and direct proteolytic degradation. Myelin basic protein (MBP) is the major structural protein component of myelin and plays a functional role in the formation and maintenance of the myelin sheath. MBP possesses endogenous serine proteinase activity and can undergo autocatalytic cleavage liberating distinct fragments. Recently, we showed that MBP binds Abeta and inhibits Abeta fibril formation (Hoos, M. D., Ahmed, M., Smith, S. O., and Van Nostrand, W. E. (2007) J. Biol. Chem. 282, 9952-9961; Hoos, M. D., Ahmed, M., Smith, S. O., and Van Nostrand, W. E. (2009) Biochemistry 48, 4720-4727). Here we show that Abeta40 and Abeta42 peptides are degraded by purified human brain MBP and recombinant human MBP, but not an MBP fragment that lacks autolytic activity. MBP-mediated Abeta degradation is inhibited by serine proteinase inhibitors. Similarly, Cos-1 cells expressing MBP degrade exogenous Abeta40 and Abeta42. In addition, we demonstrate that purified MBP also degrades assembled fibrillar Abeta in vitro. Mass spectrometry analysis identified distinct degradation products generated from Abeta digestion by MBP. Lastly, we demonstrate in situ that purified MBP can degrade parenchymal amyloid plaques as well as cerebral vascular amyloid that form in brain tissue of Abeta precursor protein transgenic mice. Together, these findings indicate that purified MBP possesses Abeta degrading activity in vitro.

Experimental autoimmune encephalomyelitis-induced upregulation of tumor necrosis factor-alpha in the dorsal root ganglia

Background: Multiple sclerosis (MS) is a chronic, neurological disease characterized by targeted destruction of central nervous system (CNS) myelin. The autoimmune theory is the most widely accepted explanation of disease pathology. Circulating Th1 cells become activated by exposure to CNS-specific antigens such as myelin basic protein. The activated Th1 cells secrete inflammatory cytokines, which are pivotal for inflammatory responses. We hypothesize that enhanced production of inflammatory cytokines triggers cellular events within the dorsal root ganglia (DRG) and/or spinal cord, facilitating the development of neuropathic pain (NPP) in MS. NPP, the second worst disease-induced symptom suffered by patients with MS, is normally regulated by DRG and/or spinal cord.

Objective: To determine gene and protein expression levels of tumor necrosis factor-alpha (TNFα) within DRG and/or spinal cord in an animal model of MS.

Methods: Experimental autoimmune encephalomyelitis (EAE) was induced in adolescent female Lewis rats. Animals were sacrificed every 3 days post-disease induction. DRG and spinal cords were harvested for protein and gene expression analysis.

Results: We show significant increases in TNFα expression in the DRG and of EAE animals at peak disease stage, as assessed by clinical symptoms.

Conclusion: Antigen-induced production of inflammatory cytokines such as TNFα within the DRG identifies a potential novel mechanism for MS-induced NPP.

Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype

Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of proinflammatory cytokine signaling, TLR signaling, and inflammatory gene expression. Furthermore, mice genetically lacking SHP-1 (me/me) display a profound susceptibility to inflammatory CNS demyelination relative to wild-type mice. In particular, SHP-1 deficiency may act predominantly in inflammatory macrophages to increase CNS demyelination as SHP-1-deficient macrophages display coexpression of inflammatory effector molecules and increased demyelinating activity in me/me mice. Recently, we reported that PBMCs of multiple sclerosis (MS) patients have a deficiency in SHP-1 expression relative to normal control subjects indicating that SHP-1 deficiency may play a similar role in MS as to that seen in mice. Therefore, it became essential to examine the specific expression and function of SHP-1 in macrophages from MS patients. Herein, we document that macrophages of MS patients have deficient SHP-1 protein and mRNA expression relative to those of normal control subjects. To examine functional consequences of the lower SHP-1, the activation of STAT6, STAT1, and NF-kappaB was quantified and macrophages of MS patients showed increased activation of these transcription factors. In accordance with this observation, several STAT6-, STAT1-, and NF-kappaB-responsive genes that mediate inflammatory demyelination were increased in macrophages of MS patients following cytokine and TLR agonist stimulation. Supporting a direct role of SHP-1 deficiency in altered macrophage function, experimental depletion of SHP-1 in normal subject macrophages resulted in an increased STAT/NF-kappaB activation and increased inflammatory gene expression to levels seen in macrophages of MS patients. In conclusion, macrophages of MS patients display a deficiency of SHP-1 expression, heightened activation of STAT6, STAT1, and NF-kappaB and a corresponding inflammatory profile that may be important in controlling macrophage-mediated demyelination in MS.

Interferon-beta treatment in multiple sclerosis attenuates inflammatory gene expression through inducible activity of the phosphatase SHP-1

Interferon-beta is a current treatment for multiple sclerosis (MS). Interferon-beta is thought to exert its therapeutic effects on MS by down-modulating the immune response by multiple potential pathways. Here, we document that treatment of MS patients with interferon beta-1a (Rebif) results in a significant increase in the levels and function of the protein tyrosine phosphatase SHP-1 in PBMCs. SHP-1 is a crucial negative regulator of cytokine signaling, inflammatory gene expression, and CNS demyelination as evidenced in mice deficient in SHP-1. In order to examine the functional significance of SHP-1 induction in MS PBMCs, we analyzed the activity of proinflammatory signaling molecules STAT1, STAT6, and NF-kappaB, which are known SHP-1 targets. Interferon-beta treatment in vivo resulted in decreased NF-kappaB and STAT6 activation and increased STAT1 activation. Further analysis in vitro showed that cultured PBMCs of MS patients and normal subjects had a significant SHP-1 induction following interferon-beta treatment that correlated with decreased NF-kappaB and STAT6 activation. Most importantly, experimental depletion of SHP-1 in cultured PBMCs abolished the anti-inflammatory effects of interferon-beta treatment, indicating that SHP-1 is a predominant mediator of interferon-beta activity. In conclusion, interferon-beta treatment upregulates SHP-1 expression resulting in decreased transcription factor activation and inflammatory gene expression important in MS pathogenesis.

Translating pathology in multiple sclerosis: the combination of postmortem imaging, histopathology and clinical findings

BACKGROUND

Studies combining postmortem magnetic resonance imaging (MRI) and histopathology have provided important insights into the abnormalities reflected by MRI.

MATERIALS AND METHODS

A short overview of these studies applied to multiple sclerosis (MS) is provided in this review, and the Amsterdam postmortem imaging protocol is specifically highlighted.

CONCLUSION

Postmortem MRI and histopathology correlation studies have enabled a direct translation of basic pathology in MS to the clinical setting, and have simultaneously served as a biological validation of new MRI techniques.

Recovery from chronic demyelination by thyroid hormone therapy: myelinogenesis induction and assessment by diffusion tensor magnetic resonance imaging

The failure of the remyelination processes in multiple sclerosis contributes to the formation of chronic demyelinated plaques that lead to severe neurological deficits. Long-term cuprizone treatment of C57BL/6 mice resulted in pronounced white matter pathology characterized by oligodendrocyte depletion, irreversible demyelination and persistent functional deficits after cuprizone withdrawal. The use of a combination of in vivo diffusion tensor magnetic resonance imaging (DT-MRI) and histological analyses allowed for an accurate longitudinal assessment of demyelination. Injection of triiodothyronine (T(3)) hormone over a 3 week interval after cuprizone withdrawal progressively restored the normal DT-MRI phenotype accompanied by an improvement of clinical signs and remyelination. The effects of T(3) were not restricted to the later stages of remyelination but increased the expression of sonic hedgehog and the numbers of Olig2(+) and PSA-NCAM(+) precursors and proliferative cells. Our findings establish a role for T(3) as an inducer of oligodendrocyte progenitor cells in adult mouse brain following chronic demyelination.

Cognitive reserve protects against cognitive dysfunction in multiple sclerosis

Cognitive reserve theory helps to explain the neuropsychological expression of neurologic disease (e.g., Alzheimer's disease; Stern, 2006). Multiple sclerosis (MS) is a neurologic disease characterized by information processing inefficiency and verbal learning and memory deficits. The current study is the first to investigate whether higher cognitive reserve moderates the relationship between MS and cognitive functioning. A word-reading proxy of premorbid intelligence was used to estimate cognitive reserve for 58 persons with MS and 43 healthy controls. Dependent measures of simple processing efficiency, complex information processing efficiency, and verbal learning and memory were administered. There were significant Group x Cognitive Reserve interactions for complex information processing efficiency and verbal learning and memory, such that persons with MS demonstrated deficits relative to controls at lower, but not higher, levels of reserve. No such interaction was found for simple processing efficiency. The protective influence of higher cognitive reserve against disease-related cognitive deficits is discussed.

Hashimoto's encephalopathy

Hashimoto's encephalopathy (HE) is a controversial neurological disorder that comprises a heterogenous group of neurological symptoms that manifest in patients with high titers of antithyroid antibodies. Clinical manifestations of HE may include encephalopathic features such as seizures, behavioral and psychiatric manifestations, movement disorders, and coma. Although it has been linked to cases of Hashimoto's thyroiditis or thyroid dysfunction, the most common immunological feature of HE is the presence of high titers of antithyroglobulin or anti-TPO (antimicrosomal) antibodies. At present, it is unclear whether antithyroid antibodies represent an immune epiphenomenon in a subset of patients with encephalopathic processes or they are really associated with pathogenic mechanisms of the disorder. The significance of classifying encephalopathies under the term HE will be determined in the future once the relevance of the role of antithyroid antibodies is demonstrated or dismissed by more detailed experimental and immunopathological studies. The responsiveness of HE to steroids or other therapies such as plasmapheresis supports the hypothesis that this is a disorder that involves immune pathogenic mechanisms. Further controlled studies of the use of steroids, plasmapheresis, or immunosuppressant medications are needed in the future to prove the concept of the pathogenic role of antithyroid antibodies in HE.

Severe oxidative damage in multiple sclerosis lesions coincides with enhanced antioxidant enzyme expression

Reactive oxygen species (ROS) and subsequent oxidative damage may contribute to the formation and persistence of multiple sclerosis (MS) lesions by acting on distinct pathological processes. ROS initiate lesion formation by inducing blood-brain barrier disruption, enhance leukocyte migration and myelin phagocytosis, and contribute to lesion persistence by mediating cellular damage to essential biological macromolecules of vulnerable CNS cells. Relatively little is known about which CNS cell types are affected by oxidative injury in MS lesions. Here, we show the presence of extensive oxidative damage to proteins, lipids, and nucleotides occurring in active demyelinating MS lesions, predominantly in reactive astrocytes and myelin-laden macrophages. Oxidative stress can be counteracted by endogenous antioxidant enzymes that confer protection against oxidative damage. Here, we show that antioxidant enzymes, including superoxide dismutase 1 and 2, catalase, and heme oxygenase 1, are markedly upregulated in active demyelinating MS lesions compared to normal-appearing white matter and white matter tissue from nonneurological control brains. Particularly, hypertrophic astrocytes and myelin-laden macrophages expressed an array of antioxidant enzymes. Enhanced antioxidant enzyme production in inflammatory MS lesions may reflect an adaptive defense mechanism to reduce ROS-induced cellular damage.

Modulation of macrophage infiltration and inflammatory activity by the phosphatase SHP-1 in virus-induced demyelinating disease

The protein tyrosine phosphatase SHP-1 is a crucial negative regulator of cytokine signaling and inflammatory gene expression, both in the immune system and in the central nervous system (CNS). Mice genetically lacking SHP-1 (me/me) display severe inflammatory demyelinating disease following inoculation with the Theiler's murine encephalomyelitis virus (TMEV) compared to infected wild-type mice. Therefore, it became essential to investigate the mechanisms of TMEV-induced inflammation in the CNS of SHP-1-deficient mice. Herein, we show that the expression of several genes relevant to inflammatory demyelination in the CNS of infected me/me mice is elevated compared to that in wild-type mice. Furthermore, SHP-1 deficiency led to an abundant and exclusive increase in the infiltration of high-level-CD45-expressing (CD45(hi)) CD11b(+) Ly-6C(hi) macrophages into the CNS of me/me mice, in concert with the development of paralysis. Histological analyses of spinal cords revealed the localization of these macrophages to extensive inflammatory demyelinating lesions in infected SHP-1-deficient mice. Sorted populations of CNS-infiltrating macrophages from infected me/me mice showed increased amounts of viral RNA and an enhanced inflammatory profile compared to wild-type macrophages. Importantly, the application of clodronate liposomes effectively depleted splenic and CNS-infiltrating macrophages and significantly delayed the onset of TMEV-induced paralysis. Furthermore, macrophage depletion resulted in lower viral loads and lower levels of inflammatory gene expression and demyelination in the spinal cords of me/me mice. Finally, me/me macrophages were more responsive than wild-type macrophages to chemoattractive stimuli secreted by me/me glial cells, indicating a mechanism for the increased numbers of infiltrating macrophages seen in the CNS of me/me mice. Taken together, these findings demonstrate that infiltrating macrophages in SHP-1-deficient mice play a crucial role in promoting viral replication by providing abundant viral targets and contribute to increased proinflammatory gene expression relevant to the effector mechanisms of macrophage-mediated demyelination.

Prevention of axonal injury using calpain inhibitor in chronic progressive experimental autoimmune encephalomyelitis

Axonal injury is the major correlate of permanent disability in neurodegenerative diseases such as multiple sclerosis (MS), especially in secondary-progressive MS which follows relapsing-remitting disease course. Proteolytic enzyme, calpain, is a potential candidate for causing axonal injury. Most current treatment options only target the inflammatory component of MS. Previous work using calpain inhibitor CYLA in our laboratory showed significant reduction in clinical sign, demyelination and tissue calpain content in acute experimental autoimmune encephalomyelitis (EAE). Here we evaluated markers of axonal injury (amyloid precursor protein, Na(v)1.6 channels), neuronal calpain content and the effect of CYLA on axonal protection using histological methods in chronic EAE [myelin oligodendrocyte glycoprotein (MOG)-induced disease model of MS]. Intraperitoneal application of CYLA (2 mg/mouse/day) significantly reduced the clinical signs, tissue calpain content, demyelination and inflammatory infiltration of EAE. Similarly, markers for axonal injury were barely detectable in the treated mice. Thus, this novel drug, which markedly suppresses the disease course, axonal injury and its progression, is a candidate for the treatment of a neurodegenerative disease such as multiple sclerosis.

Myelin repair strategies: a cellular view

PURPOSE OF REVIEW

The development of successful myelin repair strategies depends on the detailed knowledge of the cellular and molecular processes underlying demyelination and remyelination in the central nervous system of animal models and in patients with multiple sclerosis (MS). Based on the complexity of the demyelination and remyelination processes, it should be expected that effective therapeutic approaches will require a combination of strategies for immunomodulation, neuroprotection, and myelin replacement. This brief review highlights recent cellular and molecular findings and indicates that future therapeutic strategies to enhance remyelination may also require combinatorial treatment to accomplish.

RECENT FINDINGS

The relapsing-remitting course of some forms of multiple sclerosis has typically fueled hope for effective repair of multiple sclerosis lesions, if demyelinating activity could be attenuated. Recent findings support the potential of endogenous neural stem cells and progenitor cells to generate remyelinating oligodendrocytes. Importantly, interactions with viable axons and supportive astrocytic responses are required for endogenous immature cells to fulfill their potential remyelinating capacity.

SUMMARY

The research described here will help in identifying the major obstacles to effective remyelination and potential therapeutic targets to guide development of comprehensive approaches for testing in animal models and eventual treatment of patients with multiple sclerosis.

Recognition and degradation of myelin basic protein peptides by serum autoantibodies: novel biomarker for multiple sclerosis

The pathologic role of autoantibodies in autoimmune disease is widely accepted. Recently, we reported that anti-myelin basic protein (MBP) serum Abs from multiple sclerosis (MS) patients exhibit proteolytic activity toward the autoantigen. The aim of this study is to determine MBP epitopes specific for the autoantibodies in MS and compare these data with those from other neuronal disorders (OND), leading to the generation of new diagnostic and prognostic criteria. We constructed a MBP-derived recombinant "epitope library" covering the entire molecule. We used ELISA and PAGE/surface-enhanced laser desorption/ionization mass spectroscopy assays to define the epitope binding/cleaving activities of autoantibodies isolated from the sera of 26 MS patients, 22 OND patients, and 11 healthy individuals. The levels of autoantibodies to MBP fragments 48-70 and 85-170 as well as to whole MBP and myelin oligodendrocyte glycoprotein molecules were significantly higher in the sera of MS patients than in those of healthy donors. In contrast, selective reactivity to the two MBP fragments 43-68 and 146-170 distinguished the OND and MS patients. Patients with MS (77% of progressive and 85% of relapsing-remitting) but only 9% of patients with OND and no healthy donors were positive for catalysis, showing pronounced epitope specificity to the encephalitogenic MBP peptide 81-103. This peptide retained its substrate properties when flanked with two fluorescent proteins, providing a novel fluorescent resonance energy transfer approach for MS studies. Thus, anti-MBP autoantibody-mediated, epitope-specific binding and cleavage may be regarded as a specific characteristic of MS compared with OND and healthy donors and may serve as an additional biomarker of disease progression.

SHP-1 deficiency and increased inflammatory gene expression in PBMCs of multiple sclerosis patients

Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of cytokine signaling, inflammatory gene expression, and demyelination in central nervous system. The present study investigates a possible similar role for SHP-1 in the human disease multiple sclerosis (MS). The levels of SHP-1 protein and mRNA in PBMCs of MS patients were significantly lower compared to normal subjects. Moreover, promoter II transcripts, expressed from one of two known promoters, were selectively deficient in MS patients. To examine functional consequences of the lower SHP-1 in PBMCs of MS patients, we measured the intracellular levels of phosphorylated STAT6 (pSTAT6). As expected, MS patients had significantly higher levels of pSTAT6. Accordingly, siRNA to SHP-1 effectively increased the levels of pSTAT6 in PBMCs of controls to levels equal to MS patients. Additionally, transduction of PBMCs with a lentiviral vector expressing SHP-1 lowered pSTAT6 levels. Finally, multiple STAT6-responsive inflammatory genes were increased in PBMCs of MS patients relative to PBMCs of normal subjects. Thus, PBMCs of MS patients display a stable deficiency of SHP-1 expression, heightened STAT6 phosphorylation, and an enhanced state of activation relevant to the mechanisms of inflammatory demyelination.

Hygiene hypothesis: Innate immunity, malaria and multiple sclerosis

The establishment of new hygienic conditions plays a role in the appearance of autoimmunity in "westernalised" countries. Consistently, but still unconvincingly, several epidemiological and immunogenetic evidences link the disappearance of malaria with the increase of multiple sclerosis (MS) in Sardinia, insular Italy. To this purpose, we have made an attempt to build a relationship between malaria disappearance and MS under the light of the hygiene hypothesis. This relationship has taken into account the MS frequency increase soon after malaria eradication in Sardinia, the present malaria endemism in Africa, the innate immune system activity here represented by Chitotriosidase (Chit), an hydrolytic enzyme produced by macrophages, and an unproductive polymorphism of Chit gene (CHIT1) as a measure of the genetic weight of Plasmodium-related immunity in these populations. Data were derived from both experimental results specifically designed for this study and other data obtained from the available literature. The experimental and the hystorical-epidemiological findings concur to indicate that whilst in Africa CHIT1 mutation is rare and MS incidence is very low due to unmodified parasitic influence and hygienic conditions, in Sardinia a relationships between CHIT1 mutation, plasma Chit activity and MS prevalence rate is detected, even to a higher extent compared to Sicily, area at former lower rate of malaria endemy. Upon such a basis, we have found convincing argumentations that, at least in part, MS has increased over the last four decades in Sardinia also because of the eradication of malaria, 50 years ago. This infectious disease that run for centuries in Sardinia, besides well documented enzyme deficiencies and red cell pathologies, have left an abnormal macrophage reactivity against Plasmodium falciparum. As a result, some Sardinian individuals secrete abnormally high levels of mediators of the innate immunity, relics of former protective anti-malaria infection, in response to new environmental factors. Therefore, MS, an immune-conditioned pathology of the central nervous system has been subject to an unexplained epidemiological increase in the last few decades in Sardinia because cells of the innate immune system, immuno-genetically selected over the centuries in response to widespread P. falciparum malaria, have kept the tendency to over-respond to triggering factors even after the disappearance of malaria. This hypothesis may have an influence in re-directing clinicians toward a innate immunity-based rather than an antigen specific-based new MS therapies.

The extracellular matrix in multiple sclerosis pathology

The extracellular matrix (ECM) is a substrate upon which cells migrate, proliferate and differentiate. It is involved in the maintenance of cytoarchitecture, regulation of homeostasis, and it influences interactions between cells and molecules via specific receptors. Although a substantial body of knowledge has accumulated concerning the role of the ECM in peripheral tissues, little is known of the structure and function of the ECM in the CNS. However, marked changes in the expression of ECM constituents have been documented in various neurological disorders, including multiple sclerosis. This review focuses on the structure and function of the ECM in the CNS and in particular on the occurrence and involvement of ECM changes in the pathology of multiple sclerosis. Increased knowledge of the expression and functional role of ECM proteins in the CNS can lead to a better understanding of complex neurobiological processes both under normal as well as pathological conditions.

Proteomic strategies in multiple sclerosis and its animal models

The early and precise diagnosis, the prognosis, and the clinical management of multiple sclerosis, remain a considerable challenge. In recent years, the development of novel and powerful proteomic techniques prompted the use of these approaches for the search of unique biomarkers in the cerebrospinal fluid of multiple sclerosis patients. A few studies have also utilized proteomics to delineate the profile of differentially expressed proteins in animal models of the human disease in order to gain global insights into affected pathways. The identification of differentially expressed proteins may be an initial step in the discovery of novel targets and mechanisms that play critical roles in the pathology of multiple sclerosis. Based on these findings, future investigations may elucidate the events leading to demyelination, axonal damage, and neurodegeneration, providing better insights into mechanisms governing the onset and progression of the disease. Although these proteomic studies provide valuable information, they are also faced with a number of challenges. The present review discusses some of the strengths and limitations of proteomic investigations as applied to multiple sclerosis.

Myelin-basic protein-reactive specific CD4+ and CD8+ NK lymphocytes induce morphological changes in neuronal cell bodies and myelin sheaths: implications for multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic disease characterized by loss of myelin. However, data indicate that autoimmune cells could directly impair neuronal cell bodies and myelin sheath is lacking. The aim of the present study was to determine morphological evidence of the direct impairment of neurons by autoreactive lymphocytes and to further identify the subtypes of these lymphocytes.

METHODS

Lymphocytes activated by myelin basic protein (MBP) 83-99 and neurons of human brain were co-cultured for 24 h.

RESULTS

Observations through scanning electron microscope showed that MBP-specific lymphocytes (CD4+, CD8+ cells, and NK cells) aggregated in the vicinity of the neuronal cell bodies and the myelin sheaths and attacked them directly, resulting in the degeneration of both neurons.

CONCLUSIONS

Our studies provide morphological evidences of the direct impairment of neuronal cell bodies and myelin sheaths by MBP-specific lymphocytes. Our studies also suggest that MBP-specific CD4+, CD8+, and NK cells might be involved in this process. These processes may play a role in the direct impairment of neurons and myelin sheaths in early stages of MS and provide evidences for the application of immunosuppressant therapy of MS.

Technology insight: can neuroimaging provide insights into the role of ischemia in Baló's concentric sclerosis?

Baló's concentric sclerosis (BCS) has long been considered to be a variant of multiple sclerosis. Although BCS was initially described over 100 years ago, relatively few antemortem cases have been identified, and the exact pathogenesis remains unknown. Inflammatory protective ischemic preconditioning has recently been suggested as a mechanism by which the typical concentric rings of the BCS lesion are formed. Advanced neuroimaging can provide important in vivo markers of disease progression that can assist in the diagnosis and management of patients with BCS. In this Review, we discuss evidence from longitudinal neuroimaging studies that supports the role of ischemic preconditioning in BCS.

Selective vulnerability of cerebral white matter in a murine model of multiple sclerosis detected using diffusion tensor imaging

In this study, axial (lambda(parallel)) and radial (lambda(perpendicular)) diffusivities derived from diffusion tensor imaging (DTI) were used to evaluate white matter injury in brains of mice affected by experimental autoimmune encephalomyelitis (EAE). Sixteen female C57BL/6 mice were immunized with amino acids 35-55 of myelin oligodendrocyte glycoprotein (MOG(35-55)). Three months after immunization, optic nerve and tract were severely affected with 19% and 18% decrease in lambda(parallel) respectively, suggesting the presence of axonal injury. In addition, a 156% and 86% increase in lambda( perpendicular) was observed in optic nerve and tract respectively, suggestive of myelin injury. After in vivo DTI, mice were perfusion fixed and immunohistochemistry for the identification of myelin basic protein (MBP) and phosphorylated neurofilament (pNF) was performed to verify the presence of axonal and myelin injury. The present study demonstrated that the visual pathway is selectively affected in MOG(35-55) induced murine EAE and these injuries are non-invasively detectable using lambda(parallel) and lambda( perpendicular).

Cerebrovascular reactivity in multiple sclerosis patients

A close relationship between multiple sclerosis (MS) lesions and the cerebral vasculature has long been recognised. Some studies have suggested that vascular endothelial cell activation might be an early event in the evolution of MS, and demyelisation may have an ischemic basis in this condition. Hypoxia caused by breath holding (BH) results in autoregulatory vasodilatation, and an increase in CBF to the cortex. The increased CBF can be evaluated by transcranial Doppler (TCD), and can provide information about the vascular integrity. In this study, we aimed to examine the vascular integrity and assess the vasomotor reactivity of MS patients in response to BH in different activation phases of the disease by means of TCD. We studied 12 patients with clinically diagnosed relapsing remitting (RR) MS, according to the Poser criteria. The initial TCD examination was performed in the first two days of an acute exacerbation of disease and prior to any treatment. The second test was performed just after iv methylprednisolone (IVMP) treatment, and the third examination occurred one month later, when the patient was in the remission phase. A group of 11 healthy subjects was also examined by TCD as control. Blood flow velocities were recorded during 30 seconds of normal breathing and 15 seconds BH. Vasomotor reactivity was calculated as a ratio of difference of cerebral flow velocities during BH. There were no significant vasomotor reactivity differences between the controls (55.7%) and the patients during attacks (46.5%), as well as after treatment (48.3%) and during attack free periods (50.9%). There were also no significant changes amongst the patients groups throughout the study. In this study, in different disease activity stages, we observed non-significant cerebrovascular vasomotor reactivity difference between the RRMS patients and the healthy controls, although it was slightly lower in the MS patients. This observation suggests that cerebrovascular reactivity is normal in different disease activity levels.

Prospective clinical and electrophysiological follow-up on a multiple sclerosis population treated with interferon beta-1 a

Objective To analyse transcranial magnetic stimulation (TMS) variables in a prospective six-month follow-up pilot study on patients suffering from relapsing-remitting multiple sclerosis (RRMS), satisfying inclusion criteria for interferon (IFN) beta-1a treatment.

Background So far, no predictive factors are available as to the course of RRMS treated with IFN beta-1 a.

Design/methods Fifteen RRMS patients were studied before (month 0 (M0)) and after IFN beta-1a onset (M3, M6). The parameters analysed were motor functional score (mFS), Expanded Disability Status Scale (EDSS), and TMS variables - central motor conduction time (CMCT) and amplitude ratio (AR).

Results Four of the six patients with no motor signs at inclusion, subsequently showed signs of pyramidal dysfunction. All had abnormal M0_TMS variables. The number of M0_TMS abnormalities per patient was greatest in the group that showed mFS worsening, and was significantly correlated with M6_EDSS. The M0_CMCT was significantly correlated with M6_EDSS. During follow-up, the number of patients with abnormal TMS variables decreased from 12/15 to 4/15, and the total number of abnormalities decreased from 33.3 to 16.7%.

Conclusions TMS variables might be predictive of disease progression. The improvement observed here in the TMS variables may reflect an improvement in MS patients undergoing IFN beta treatment. Multiple Sclerosis 2007; 13: 348-356. http://msj.sagepub.com

Haplotype matching is not an essential requirement to achieve remyelination of demyelinating CNS lesions

Transplantation of oligodendrocyte precursor cells (OPCs) results in efficient remyelination in animal models of demyelination. However, the experiments so far undertaken have not addressed the need for tissue-type matching to achieve graft-mediated remyelination. Examination of MHC expression (main determinant of allograft rejection) by OPCs showed nondetectable levels under standard culture conditions and upregulation of MHC Class I expression only upon exposure to interferon gamma. We therefore hypothesized that MHC matching of OPC grafts may not be crucial to achieve transplant-mediated remyelination. Transplant experiments performed using a nonself repairing toxin-induced demyelination model showed that, similarly to allogeneic neurons, survival of allogeneic oligodendrocyte lineage cells is influenced by donor-host haplotype combination and graft composition. Transplantation of allogeneic mixed glial cell cultures resulted in remyelination failure by 1 month postengraftment due to a rejection response targeting both myelinating oligodendrocytes and OPCs, suggesting that inflammation-induced upregulation of OPC MHC I expression results in susceptibility to cytotoxic T cell attack. In contrast, remyelination persisted for at least 2 months following transplantation of OPC-enriched cultures whose overall MHC expression level was significantly decreased. While OPC-enriched preparations elicited delayed type hypersensitivity responses in hosts sensitized to alloantigens, allografting of such preparations into a central nervous system demyelinating lesion did not result in recipient priming. We conclude that while allografted oligodendrocyte lineage cells become targets of a graft rejection response once this response has been initiated, transplantation of OPC-enriched preparations can evade priming against alloantigens and graft rejection. This finding indicates that close tissue matching may not be an essential requirement for successful transplant-mediated remyelination.

Prognostic Factors in Multiple Sclerosis

Prognostic factors to determine the patient's likelihood of developing MS are important for several reasons. Prognostic factors are important to the patient who wants to be informed about his/her prospects, to the clinician who needs to individuate the patients who deserve immune treatments, and to the researcher who needs to improve the design and the analysis of the therapeutic trials. In addition, with the development of new immune therapies, whose early use is strongly encouraged, it is crucial to dispose of reliable clinical predictors to identify the patients who are candidates for early or aggressive therapies. Several studies have indicated that a poor prognosis is related to male gender; a late age at onset; motor, cerebellar, and sphincter involvement at onset; a progressive course at onset; a short inter-attack interval; a high number of early attacks; and a relevant early residual disability. Paraclinical support for MS prognosis is given by imaging techniques, cerebrospinal fluid analysis, and evoked potential examinations. The most sensitive paraclinical test to predict conversion from suspected demyelinating disease to definite MS is MRI.

Intrathecal chitotriosidase and the outcome of multiple sclerosis

Activated macrophages are major effectors at all stages of lesion formation in multiple sclerosis (MS) brain. Here, we report that the macrophage enzyme chitotriosidase (Chit) is significantly elevated both in plasma and cerebrospinal fluid (CSF) of patients with MS as compared to healthy controls and other neurological patients (P<0.001). Furthermore, the Chit activity in blood significantly associates with the MS clinical course (higher in secondary progressive relative to relapsing-remitting, P=0.01) and the clinical severity as measured by Kurtkze's Expanded Disability Status Scale (P<0.001). Also, we found that Chit activity is compartmentalized in the central nervous system of early MS patients and that its CSF/plasma quotient, in the presence of a preserved albumin quotient, correlates with the extent of future clinical deterioration (r=0.91; P<0.001). These findings confirm that innate immunity, here represented by Chit, is clinically relevant in MS and allows, if confirmed, reconsidering novel MS therapeutic strategies specifically aimed at this branch of the immune response.

Gene-environment interactions in multiple sclerosis: innate and adaptive immune responses to human endogenous retrovirus and herpesvirus antigens and the lectin complement activation pathway

Aspects of gene-environment interactions in multiple sclerosis (MS) were analysed in serum samples from 46 MS families (25 sporadic MS cases and 42 familial MS cases): antibodies to the MS-associated human endogenous retrovirus HERV-H, and levels of three components in the innate pathogen-associated molecular pattern recognition: mannan-binding lectin (MBL), and MASP-2 and MASP-3. For representative MS families, we also determined herpesvirus serology for HSV-1, VZV, and EBV; and tissue typed for HLA-B, and HLA DR and DQ. In MS, a significant correlation between elevated immune reactivity to HERV-H Env and disease activity was demonstrated, as were indications of a protective effect of high MBL and MASP-3 levels. The HLA alleles B*07, DRB*02, and DQB1*06 were commonly present together in the MS families, both in MS patients, and in unaffected family members. Our results support that HERV-H and the antiviral immune response may play a role in MS development, and also underline the tenuous nature of specific genetic contributions to this complex disease.

A novel calpain inhibitor for the treatment of acute experimental autoimmune encephalomyelitis

Aberrant activation of calpain plays a key role in the pathophysiology of several neurodegenerative disorders. Calpain is increasingly expressed in inflammatory cells in EAE and is significantly elevated in the white matter of patients with multiple sclerosis, thus calpain inhibition could be a target for therapeutic intervention. The experiments reported here employed a myelin oligodendrocyte glycoprotein-induced disease model in C57Bl/6 mice (EAE) and a novel calpain inhibitor, targeted to nervous tissue. CYLA was found to reduce clinical signs of EAE and prevent demyelination and inflammatory infiltration in a dose- and time-dependent manner. Oral administration of the diacetal prodrug was equally effective.

Multiple sclerosis is linked to Epstein-Barr virus infection

The aetiology and pathogenesis of MS are unknown, but environmental agents, genetic susceptibility and stochastic events are likely to be involved. In order to evaluate the possibility that MS is linked to EBV infection, we here evaluate studies on MS- and EBV-epidemiology, prospective and retrospective analysis of EBV-serology, investigations of EBV DNA sequences in blood and tissues, specificity of antibodies in oligoclonal bands in MS patients and results from antiviral chemotherapy of MS patients. It could be demonstrated that EBV is complying with the epidemiological observations in MS and that all MS patients are seropositive to EBV in contrast to healthy controls. Importantly, despite difficulties in diagnosing child-MS, the vast majority of these patients are also EBV seropositive. In contrast to control groups, recent EBV infections have never been observed in children or adults with MS. Further prospective studies indicate a 2.8 times higher tendency for development of MS after infectious mononucleosis. In MS patients, unbiased analyses pull out EBV antigens as high-affinity targets for the antibodies in the oligoclonal bands. Humans are the exclusive natural host for EBV, a finding that may explain why MS is unique to humans. Together these unique observations strongly suggest a linkage between MS and EBV infection. Infection by EBV offers numerable mechanisms to perturb the immune system, including mimicry and superantigen induction, which may potentially participate in the disease mechanisms. In contrast, studies demonstrating higher IgG titres and occurrence of viral DNA in serum/plasma are likely to reflect a consequence of the disease. An explanation for a potential role of respiratory diseases in MS is discussed. It is concluded that the ultimate test to the hypothesis of MS and EBV is the development and application of an EBV vaccine, which is predicted to eradicate the disease.

Lumbar cerebrospinal fluid proteome in multiple sclerosis: characterization by ultrafiltration, liquid chromatography, and mass spectrometry

Neurological diseases, including multiple sclerosis (M.S.), often provoke changes in the functioning of the endothelial and epithelial brain barriers and give rise to disease-associated alterations of the cerebrospinal fluid (CSF) proteome. In the present study, pooled and ultrafiltered CSF of M.S. and non-M.S. patients was digested with trypsin and analyzed by off-line strong cation-exchange chromatography (SCX) coupled to on-line reversed-phase LC-ESI-MS/MS. In an alternative approach, the trypsin-treated subproteomes were analyzed directly by LC-ESI-MS/MS and gas-phase fractionation in the mass spectrometer. Taken together, both proteomic approaches in combination with a three-step evaluation process including the search engines Sequest and Mascot, and the validation software Scaffold, resulted in the identification of 148 proteins. Sixty proteins were identified in CSF for the first time by mass spectrometry. For validation purposes, the concentration of cystatin A was determined in individual CSF and serum samples of M.S. and non-M.S. patients using ELISA.

Intrathecal IgM production at clinical onset correlates with a more severe disease course in multiple sclerosis

The intrathecal synthesis of IgM, determined at clinical onset in patients with multiple sclerosis, was found to correlate with the degree of disability (as evaluated by means of the Expanded Disability Status Scale) reached 15 years later (p<0.001). Moreover, a significant inverse correlation was observed between the value of the IgM index and time to the first relapse (p<0.001) and the initiation of the progressive phase of the disease (p = 0.01). The prognostic value of IgM in the CSF is confirmed in previous reports as well as by our study. If these findings are confirmed in patients with multiple sclerosis in a larger series, a helpful biological marker for selecting patients for immunomodulatory treatments will be available to neurologists.