Manganese-Enhanced MRI in Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: Cellular uptake of the manganese ion, when administered as a contrast agent for MR imaging, can noninvasively highlight cellular activity and disease processes in both animals and humans. The purpose of this study was to explore the enhancement profile of manganese in patients with multiple sclerosis. MATERIALS AND METHODS: Mangafodipir is a manganese chelate that was clinically approved for MR imaging of liver lesions. We present a case series of 6 adults with multiple sclerosis who were scanned at baseline with gadolinium, then injected with mangafodipir, and followed at variable time points thereafter. RESULTS: Fourteen new lesions formed during or shortly before the study, of which 10 demonstrated manganese enhancement of varying intensity, timing, and spatial pattern. One gadolinium-enhancing extra-axial mass, presumably a meningioma, also demonstrated enhancement with manganese. Most interesting, manganese enhancement was detected in lesions that formed in the days after mangafodipir injection, and this enhancement persisted for several weeks, consistent with contrast coming from intracellular uptake of manganese. Some lesions demonstrated a diffuse pattern of manganese enhancement in an area larger than that of both gadolinium enhancement and T2-FLAIR signal abnormality. CONCLUSIONS: This work demonstrates the first use of a manganese-based contrast agent to enhance MS lesions on MR imaging. Multiple sclerosis lesions were enhanced with a temporal and spatial profile distinct from that of gadolinium. Further experiments are necessary to uncover the mechanism of manganese contrast enhancement as well as cell-specific uptake.

Manganese-Enhanced MRI of the Brain in Healthy Volunteers.

BACKGROUND AND PURPOSE: The manganese ion is used as an intracellular MR imaging contrast agent to study neuronal function in animal models, but it remains unclear whether manganese-enhanced MR imaging can be similarly useful in humans. Using mangafodipir (Teslascan, a chelated manganese-based contrast agent that is FDA-approved), we evaluated the dynamics of manganese enhancement of the brain and glandular structures in the rostral head and neck in healthy volunteers. MATERIALS AND METHODS: We administered mangafodipir intravenously at a rate of 1 mL/minute for a total dose of 5 µmol/kg body weight. Nine healthy adult volunteers (6 men/3 women; median age, 43 years) completed baseline history and physical examination, 3T MR imaging, and blood work. MR imaging also followed mangafodipir administration at various time points from immediate to 7 days, with delayed scans at 1-3 months. RESULTS: The choroid plexus and anterior pituitary gland enhanced within 10 minutes of infusion, with enhancement persisting up to 7 and 30 days, respectively. Exocrine (parotid, submandibular, sublingual, and lacrimal) glands also enhanced avidly as early as 1 hour postadministration, generally resolving by 1 month; 3 volunteers had residual exocrine gland enhancement, which resolved by 2 months in 1 and by 3 months in the other 2. Mangafodipir did not affect clinical parameters, laboratory values, or T1-weighted signal in the basal ganglia. CONCLUSIONS: Manganese ions released from mangafodipir successfully enable noninvasive visualization of intra- and extracranial structures that lie outside the blood-brain barrier without adverse clinical effects, setting the stage for future neuroradiologic investigation in disease.

Improved Visualization of Cortical Lesions in Multiple Sclerosis Using 7T MP2RAGE.

BACKGROUND AND PURPOSE: Cortical lesions are common and often extensive in multiple sclerosis but are difficult to visualize by MRI, leaving important questions about their clinical implications and response to therapy unanswered. Our aim was to determine whether cortical lesions are better visualized using magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE) than T2*-weighted imaging on 7T MR imaging. MATERIALS AND METHODS: Brain MR imaging using T1-weighted MP2RAGE at 500-µm isotropic resolution, T2*-weighted gradient-echo, and T2*-weighted segmented echo-planar imaging sequences were collected for 13 patients with MS and 5 age-matched neurologically healthy controls on a 7T research system. One MS case underwent postmortem MR imaging including gradient-echo and MP2RAGE sequences, after which cortical lesions seen on MR imaging were assessed with immunohistochemistry. RESULTS: MP2RAGE detected 203 cortical lesions (median, 16 lesions/case; interquartile range, 15), compared to 92 with T2*gradient-echo (median, 7; interquartile range, 8; P < .001) and 81 with T2*EPI (median, 7; interquartile range, 5; P < .001). This increase in lesion number detected on MP2RAGE versus T2* was observed for juxtacortical, leukocortical, and intracortical lesions. Forty-three percent of all cortical lesions were identified only on MP2RAGE. White matter lesion volume correlated with total juxtacortical (r = 0.86, P < .001) and leukocortical lesion volume (r = 0.70, P < .01) but not intracortical lesion volume, suggesting that pathophysiology may differ by lesion type. Of 4 suspected lesions seen on postmortem imaging, 3 were found to be true cortical lesions while 1 represented postmortem tissue damage. CONCLUSIONS: A combination of MP2RAGE and T2*-weighted imaging at 7T improved detection of cortical lesions and should enable longitudinal studies to elucidate their spatiotemporal dynamics and clinical implications.

Evidence-based guideline update: Plasmapheresis in neurologic disorders: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.

OBJECTIVE: To reassess the role of plasmapheresis in the treatment of neurologic disorders. METHODS: We evaluated the available evidence based on a structured literature review for relevant articles from 1995 through September 2009. In addition, due to revision of the definitions of classification of evidence since the publication of the previous American Academy of Neurology assessment in 1996, the evidence cited in that manuscript was reviewed and reclassified. RESULTS AND RECOMMENDATIONS: Plasmapheresis is established as effective and should be offered in severe acute inflammatory demyelinating polyneuropathy (AIDP)/Guillain-Barré syndrome (GBS) and in the short-term management of chronic inflammatory demyelinating polyneuropathy (Class I studies, Level A). Plasmapheresis is established as ineffective and should not be offered for chronic or secondary progressive multiple sclerosis (MS) (Class I studies, Level A). Plasmapheresis is probably effective and should be considered for mild AIDP/GBS, as second-line treatment of steroid-resistant exacerbations in relapsing forms of MS, and for neuropathy associated with immunoglobulin A or immunoglobulin G gammopathy, based on at least one Class I or 2 Class II studies (Level B). Plasmapheresis is probably not effective and should not be considered for neuropathy associated with immunoglobulin M gammopathy, based on one Class I study (Level B). Plasmapheresis is possibly effective and may be considered for acute fulminant demyelinating CNS disease (Level C). There is insufficient evidence to support or refute the use of plasmapheresis for myasthenia gravis, pediatric autoimmune neuropsychiatric disorders associated with streptococcus infection, and Sydenham chorea (Class III evidence, Level U).

CD4+CD28- costimulation-independent T cells in multiple sclerosis.

Multiple lines of evidence suggest that CD4+ lymphocytes initiate autoimmune responses against myelin antigens in multiple sclerosis (MS). The increased frequency of activated myelin-specific cells in MS patients indicates that the activation of autoreactive cells represents a central event in the pathogenesis of the disease. We identified a CD4+ subpopulation that is characterized phenotypically by the persistent absence of surface CD28 expression and functionally by CD28-independent activation and Th1 cytokine secretion. Owing to their costimulation-independent activation and their expression of a full agonist signaling activation pattern, CD4+CD28- cells have the potential to initiate autoimmune responses in the central nervous system, a compartment devoid of professional antigen presenting cells. Long-term memory CD4+CD28- cells produce high amounts of IFN-gamma and maximally upregulate IFN-gamma and IL-12Rbeta2 chain expression in the absence of costimulation. They exhibit prominent growth characteristics and increased survival after activation, likely related to their persistent lack of CTLA-4 surface expression. The CD4+CD28- population is expanded in a subgroup of MS patients. Myelin basic protein-specific cells detected in this cell subset may play an important role in the inflammatory response within the central nervous system.

Dendritic cells signal T cells in the absence of exogenous antigen.

Interactions with self-major histocompatibility complex molecules on dendritic cells (DCs) are important for the survival of mature CD4+ T cells. We have followed the DC-mediated signal from the T cell surface to the nucleus and identified a pattern of activation that correlates with increased in vitro survival. This response is induced exclusively by DCs and is likely associated with a modulation of the T cell activation threshold. We have also found that DC-mediated activation results in antigen-independent cytokine gene expression, which points to a new role for DCs in shaping the cytokine milieu. Such antigen-independent activation of T cells may play a role in protective immunity, but may also induce and perpetuate autoimmune states such as multiple sclerosis.

Cross-reactive phage-displayed mimotopes lead to the discovery of mimicry between HSV-1 and a brain-specific protein.

We previously reported the selection of several families of phage-displayed peptide mimics (mimotopes) recognized by oligoclonal immunoglobulins present in the CSF of multiple sclerosis (MS) patients. To search for the natural antigens recognized by these antibodies, anti-sera were raised against one of the mimotopes and used as a probe in ELISA, Western blotting and immunoprecipitation experiments. Anti-mimotope IgG were found to cross-react with an epitope shared by a brain-specific factor conserved from rodents to humans, and the surface glycoprotein gB of HSV-1. These findings support the hypothesis that common viral infections are the triggering agents of self-reactive CSF antibodies, whose role in MS still remains to be elucidated.

Encephalitogenic potential of the myelin basic protein peptide (amino acids 83-99) in multiple sclerosis: results of a phase II clinical trial with an altered peptide ligand.

Myelin-specific T lymphocytes are considered essential in the pathogenesis of multiple sclerosis. The myelin basic protein peptide (a.a. 83-99) represents one candidate antigen; therefore, it was chosen to design an altered peptide ligand, CGP77116, for specific immunotherapy of multiple sclerosis. A magnetic resonance imaging-controlled phase II clinical trial with this altered peptide ligand documented that it was poorly tolerated at the dose tested, and the trial had therefore to be halted. Improvement or worsening of clinical or magnetic resonance imaging parameters could not be demonstrated in this small group of individuals because of the short treatment duration. Three patients developed exacerbations of multiple sclerosis, and in two this could be linked to altered peptide ligand treatment by immunological studies demonstrating the encephalitogenic potential of the myelin basic protein peptide (a.a. 83-99) in a subgroup of patients. These data raise important considerations for the use of specific immunotherapies in general.

Minimal peptide length requirements for CD4(+) T cell clones--implications for molecular mimicry and T cell survival.

CD4(+) T lymphocytes usually recognize peptides of 12-16 amino acids in the context of HLA class II molecules. We have recently used synthetic peptide combinatorial libraries to dissect in detail antigen recognition by autoreactive CD4(+) T cell clones (TCC). The results of these studies demonstrated that antigen recognition by T cells is highly degenerate and that many cross-reactive ligands can be defined, some of which much more potent than the selecting autoantigen. Based on these observations, we examined the response of a myelin basic protein-specific HLA class II-restricted CD4(+) TCC to truncation variants of optimal ligands. Surprisingly, pentapeptides, tetrapeptides and even tripeptides derived from different segments of the optimal ligands were recognized by the TCC, and some were even more potent than the selecting autoantigen. In addition, these peptides enhanced the survival of the TCC at low concentration. The relevance of this finding was supported by the generation of pentapeptide-specific CD4(+) TCC from peripheral blood lymphocytes. These observations not only change existing views on the length requirements for activation of CD4(+) HLA class II-restricted T cells, but also extend our knowledge about the flexibility of TCR recognition and the potential for cross-reactivity in the immune system.

Identification of candidate T-cell epitopes and molecular mimics in chronic Lyme disease.

Elucidating the cellular immune response to infectious agents is a prerequisite for understanding disease pathogenesis and designing effective vaccines. In the identification of microbial T-cell epitopes, the availability of purified or recombinant bacterial proteins has been a chief limiting factor. In chronic infectious diseases such as Lyme disease, immune-mediated damage may add to the effects of direct infection by means of molecular mimicry to tissue autoantigens. Here, we describe a new method to effectively identify both microbial epitopes and candidate autoantigens. The approach combines data acquisition by positional scanning peptide combinatorial libraries and biometric data analysis by generation of scoring matrices. In a patient with chronic neuroborreliosis, we show that this strategy leads to the identification of potentially relevant T-cell targets derived from both Borrelia burgdorferi and the host. We also found that the antigen specificity of a single T-cell clone can be degenerate and yet the clone can preferentially recognize different peptides derived from the same organism, thus demonstrating that flexibility in T-cell recognition does not preclude specificity. This approach has potential applications in the identification of ligands in infectious diseases, tumors and autoimmune diseases.

Effects of early postnatal exposure to low concentrations of carbon monoxide on cognitive functions in rats.

Male Wistar rats were exposed to 75 and 150 ppm of carbon monoxide (CO) from day 1 after birth until postnatal day 10 and their cognitive functions were evaluated at 3 and 18 months of age. The results show that early postnatal exposure to CO does not affect the acquisition and reacquisition of an active avoidance task in both adult and aged rats. Conversely, our previous findings indicate that prenatal exposure to CO (75 and 150 ppm), resulting in maternal blood carboxyhaemoglobin concentrations equivalent to those found in human cigarette smokers, induces long-lasting learning and memory deficits. These findings suggest that neurofunctional sequelae of prenatal CO exposure are notably different from those occurring in response to early postnatal exposure and that the vulnerability of the developing brain to prolonged, relatively mild, decrease in oxygen availability induced by CO critically depends on the particular period of developmental exposure.

CSF-enriched antibodies do not share specificities among MS patients.

The specificity of the oligoclonal immunoglobulins found in MS CSF is unknown. We have previously shown that random peptide libraries displayed on phage can be used to identify specific ligands for CSF antibodies. Here we describe the use of this tool in the attempt to identify MS-specific CSF-enriched antibody reactivities with potential pathogenic, diagnostic or prognostic value. Applying different experimental strategies, several ligands reacting with CSF-enriched antibodies were identified. When tested against a panel of 55 MS patients, none of the ligands found were recognized by antibodies shared by any two patients. We used the selected peptides to demonstrate the stability in time of CSF-enriched antibodies notwithstanding disease progression.

Identification of peptides binding to IgG in the CSF of multiple sclerosis patients.

Phage displayed random peptide libraries were screened in order to identify phagotopes reacting with the IgG present in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients. Six families of phagotopes each composed of different isolates were identified. These phagotopes were used as reagents, to characterise IgG present in the CSF of MS patients. The following results were obtained: (a) CSF antibodies from different patients display different specificities; (b) anti-phagotope antibodies are also present in the serum of MS patients; (c) Anti-phagotope antibodies are equally frequent in the serum of MS patients and of healthy individuals; (d) some of the anti-phagotope antibodies are enriched in the CSF of MS patients. These data show that the natural antigen(s) recognised by CSF antibodies is rather common in the general population. By using the selected phagotopes as immunogens in rabbits, we have derived large quantities of anti-phagotope antisera which can provide for useful tools toward the identification of the natural antigen(s) recognised by MS CSF antibodies.

Selection of biologically active peptides by phage display of random peptide libraries.

Random peptide libraries displayed on phage are used as a source of peptides for epitope mapping, for the identification of critical amino acids responsible for protein-protein interactions and as leads for the discovery of new therapeutics. Efficient and simple procedures have been devised to select peptides binding to purified proteins, to monoclonal and polyclonal antibodies and to cell surfaces in vivo and in vitro.

Identification of peptides specific for cerebrospinal fluid antibodies in multiple sclerosis by using phage libraries.

The study of the origin and pathogenetic relevance of the oligoclonal antibodies present in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients has been hampered by a lack of specific ligands. We recently reported a general strategy, based on phage-displayed random peptide libraries, to identify ligands for disease-specific antibodies even in the absence of any information on the nature of the pathologic antigen. With this procedure, we identified several peptides specifically recognized by antibodies present in the CSF of MS patients. Using these peptides as reagents, we demonstrated that they mimic different natural epitopes and react with antibodies enriched in the CSF of MS patients. Antibodies recognizing the selected peptides are commonly found with equal frequency in the sera of MS patients and of normal individuals. In contrast, the repertoire of CSF antibodies appears to be individual-specific and is probably the result of a nonspecific immunodysregulation rather than a stereotyped response to a single antigen/agent.

[Therapy of non-ulcer dyspepsia]. / Terapia della dispepsia non ulcerosa.

The authors describe the gastro-kinetic drugs that act on functional dyspepsia including metoclopramide, domperidone, clebopride cisapride. Moreover, in some forms of non-ulcer dyspepsia it is useful to give sulglicotide, a cytoprotective drug that has been shown to induce marked improvement of clinical symptoms and endoscopic findings.

Behavioural changes in rats after prenatal administration of typical and atypical antidepressants.

Prenatal administration of typical (desipramine, DMI) and atypical (viloxazine, VX and mianserin, MS) antidepressants, at dose levels which do not influence reproductive success or neonatal mortality, produces subtle behavioural changes in offspring of treated rats. Physical signs, such as pinna detachment (unfolding of external ear) and eye opening, were not modified by prenatal exposure to any of the antidepressants tested. However, at 23 days of age, DMI, MS and VX (only in males) pretreated rats showed higher levels of locomotor activity with respect to the control group. At 60 days of age, locomotor activity levels in DMI-exposed animals were still higher than in the saline-pretreated rats.