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Biomedical subjects

Catherine Lubetzki

Publications and source records attributed to Catherine Lubetzki.

16 recordsLinked to original sources
PubMed2006

[Therapeutic perspectives in multiple sclerosis].

Although consistent progress has been made over the last decade in the treatment of the inflammatory component of multiple sclerosis, these strategies have only partial efficacy. Numerous innovative therapeutic perspectives are emerging: currently, monoclonal antibody induced inhibition of entry of activated lymphocytes into the central nervous system is promising, but the benefit/risk ratio has still to be evaluated. In parallel, combination strategies with immunomodulators and/or immunosuppressants, and specific immunotherapy are investigated. In addition, in the longer-term, there is active development of experimental strategies aimed at repairing damaged tissue--both axon and myelin. These strategies are still at the preclinical stage. Therapeutic optimisation may come from an association between anti-inflammatory treatments acting upstream on the immune response, and neuroprotective and myelin repair strategies acting downstream, directed at the lesions.

Adjuvants, Immunologic↗
PubMed2006

Imaging of CNS myelin by positron-emission tomography.

Promoting myelin repair is one of the most promising therapeutic avenues in the field of myelin disorders. In future clinical trials, evaluation of remyelination will require a reliable and quantifiable myelin marker to be used as a surrogate marker. To date, MRI assessment lacks specificity for evaluating the level of remyelination within the brain. Here, we describe 1,4-bis(p-aminostyryl)-2-methoxy benzene (BMB), a synthesized fluorescent molecule, that binds selectively to myelin both ex vivo and in vivo. The binding of BMB to myelin allows the detection of demyelinating lesions in an experimental autoimmune encephalitis model of demyelination and allows a mean for quantifying myelin loss in dysmyelinating mutants. In multiple sclerosis brain, different levels of BMB binding differentiated remyelination in shadow plaques from either demyelinated lesions or normal-appearing white matter. After systemic injection, BMB crosses the blood-brain barrier and binds to myelin in a dose-dependent and reversible manner. Finally, we provide evidence that (11)C-radiolabeled BMB can be used in vivo to image CNS myelin by positron-emission tomography in baboon. Our results provide a perspective for developing a brain myelin imaging technique by positron-emission tomography.

Animals↗
PubMed2006

A novel fluorescent probe that is brain permeable and selectively binds to myelin.

Myelin is a multilayered glial cell membrane that forms segmented sheaths around large-caliber axons of both the central nervous system (CNS) and peripheral nervous system (PNS). Myelin covering insures rapid and efficient transmission of nerve impulses. Direct visual assessment of local changes of myelin content in vivo could greatly facilitate diagnosis and therapeutic treatments of myelin-related diseases. Current histologic probes for the visualization of myelin are based on antibodies or charged histochemical reagents that do not enter the brain. We have developed a series of chemical compounds including (E,E)-1,4-bis(4'-aminostyryl)-2-dimethoxy-benzene termed BDB and the subject of this report, which readily penetrates the blood-brain barrier and selectively binds to the myelin sheath in brain. BDB selectively stains intact myelinated regions in wild-type mouse brain, which allows for delineation of cuprizone-induced demyelinating lesions in mouse brain. BDB can be injected IV into the brain and selectively detect demyelinating lesions in cuprizone-treated mice in situ. These studies justified further investigation of BDB as a potential myelin-imaging probe to monitor myelin pathology in vivo.

Aniline Compounds↗
PubMed2006

Atypical Gilles de la Tourette Syndrome with beta-mannosidase deficiency.

BACKGROUND: beta-Mannosidosis is a rare inborn error of metabolism with various phenotypes, including mental retardation, behavioral problems, hearing loss, and recurrent airway infections in childhood. To our knowledge, there is no published description of Gilles de la Tourette syndrome in association with this enzymatic deficiency. OBJECTIVE: To describe a unique case of Gilles de la Tourette syndrome associated with beta-mannosidosis. SETTING: University hospital. Patient An 18-year-old man exhibited motor and vocal tics since childhood, attention-deficit/hyperactivity disorder, impulsivity, and aggressiveness compatible with Gilles de la Tourette syndrome. A screen for inborn errors of metabolism was made because of the atypical association with slight mental retardation and bilateral perceptive hypoacousia. RESULTS: Urinary analysis showed disacchariduria, and leukocyte analysis revealed a profound deficit in beta-mannosidase activity. Two novel mutations in the beta-mannosidase gene were found: a new splice mutation in one allele, and a unique 10-base-pair insertion in the other. CONCLUSIONS: This case illustrates the phenotypic variability of inborn errors of metabolism in adults and demonstrates the need to screen inborn errors of metabolism in atypical Gilles de la Tourette syndrome.

Adolescent↗
PubMed2005

Axonal signals in central nervous system myelination, demyelination and remyelination.

Axonal signals are key players in central nervous system myelination. During development, the onset of myelination depends on a balance between positive and negative axonal signals. Among negative signals are inhibitory adhesion molecules that need to be removed from the cell surface for the myelination process to proceed. Positive signals necessary to initiate myelination consist of both interactions with specific adhesion molecules and electrical activity-induced release of promyelinating factors. In multiple sclerosis, demyelination induces major modifications of axonal surface components. The disruption of these factors might participate to the failure of the myelin repair process.

Animals↗
PubMed2005

Promoting repair in multiple sclerosis: problems and prospects.

PURPOSE OF REVIEW: Despite recent progress in treating the inflammatory component of multiple sclerosis, current therapies have no clear impact on progression of disability, which closely relates to tissue (myelin and axon) injury. Many scientists now focus their efforts on elucidating the mechanisms that lead to tissue injury, and on developing new strategies for tissue repair. We review recent breakthroughs in this field and discuss their putative applications to therapy. RECENT FINDINGS: Several hypotheses have been raised to explain the failure of remyelination, including depletion of remyelinating cells, quiescence of oligodendrocyte precursor cells and axonal inhibitory signals. Success in remyelination therapy may be achieved either by enhancing endogenous repair or by grafting exogenous remyelinating cells. Several neurotrophic factors have been shown to enhance endogenous remyelination, and many immature cells have been shown to induce efficient exogenous remyelination in animal models. Although effective remyelination probably represents the best way to prevent neurodegeneration, several alternative neuroprotective strategies are emerging. Statins, cyclins and immunophilin ligands are orally available immunomodulatory agents that may protect neurones. Other promising possibilities include the modulation of excitotoxicity, nitric oxide synthesis, or cationic channels. SUMMARY: Despite the increasing number of putative therapeutic targets, no treatment to achieve remyelination or neuroprotection has yielded positive clinical results in humans. Forging a link between basic biology and treatment of patients will require us to overcome several challenges, including assessment of efficacy of repair, improving tolerance to and delivery of neurotrophic factors, and better defining the indications for and limitations of transplantation.

Animals↗
PubMed2004

First episode of acute CNS inflammatory demyelination in childhood: prognostic factors for multiple sclerosis and disability.

OBJECTIVES: To evaluate prognostic factors for second attack and for disability in children presenting with an initial episode of central nervous system (CNS) demyelination. STUDY DESIGN: A cohort of 296 children having a first episode of acute CNS inflammatory demyelination was studied by survival analysis. RESULTS: The average follow-up was 2.9+/-3 years. At the end of the follow-up, 57% of patients had a diagnosis of multiple sclerosis (MS), 29% had a monophasic acute disseminated encephalomyelitis, and 14% had a single focal episode. The rate of a second attack was (1). higher in patients with age at onset >or=10 years (hazard ratio, 1.67; 95% CI, 1.04-2.67), MS-suggestive initial MRI (1.54; 1.02-2.33), or optic nerve lesion (2.59; 1.27-5.29); and (2). lower in patients with myelitis (0.23; 0.10-0.56) or mental status change (0.59; 0.33-1.07). Of patients with a second attack, 29% had an initial diagnosis of acute disseminated encephalomyelitis. At the end of the follow-up period, 90% of patients had no or minor disability. Occurrence of severe disability was associated with a polysymptomatic onset (3.25; 1.16-11.01), sequelae after the first attack (26.65; 9.42-75.35), further relapses (1.49; 1.16-1.92), and progressive MS (3.57; 1.21-8.72). CONCLUSIONS: Risk of second attack of CNS demyelination is higher in older patients and lower in patients with mental status change. Risk of disability is higher in polysymptomatic and relapsing patients.

Acute Disease↗
PubMed2003

The transmembrane semaphorin Sema4D/CD100, an inhibitor of axonal growth, is expressed on oligodendrocytes and upregulated after CNS lesion.

Semaphorins are a family of secreted and membrane-bound proteins, known to regulate axonal pathfinding. Sema4D, also called CD100, was first isolated in the immune system where it is involved in B and T cell activation. We found that in the mouse, Sema4D is expressed in cells throughout the CNS white matter, with a peak during the myelination period. Double-labeling experiments with different markers of oligodendrocyte lineage such as olig1, olig2, platelet-derived growth factor receptor alpha, and proteolipid protein showed that Sema4D was expressed selectively by oligodendrocytes and myelin. The presence of Sema4D in myelin was confirmed using Western blot. Sema4D expression in myelinating oligodendrocytes was further observed using neuron-oligodendrocyte cocultures. Moreover, using stripe assay, we found that Sema4D is strongly inhibitory for postnatal sensory and cerebellar granule cell axons. This prompted us to examine whether Sema4D expression is modified after CNS injury. At 8 d after spinal cord lesions, Sema4D expression was strongly upregulated in oligodendrocytes at the periphery of the lesion. Sema4D-positive cells were not colabeled with the astrocyte marker GFAP, with the microglial and macrophagic marker isolectin B4, or with NG2, a marker of oligodendrocyte precursors. This upregulation was transient because from 1 month after the lesion, Sema4D expression was back to its normal level. These results indicate that Sema4D is a novel inhibitory factor for axonal regeneration expressed in myelin.

Animals↗
PubMed2003

Multiple sclerosis tremor and the Stewart-Holmes manoeuvre.

The objective of this study is to define tremor and cerebellar dysfunction and determine whether kinetic and postural tremor correlate with cerebellar dysfunction in patients with multiple sclerosis (MS). Cerebellar symptoms such as dysmetria often interfere with tremor evaluation in MS. The Stewart-Holmes (SH) manoeuvre, which has been recently quantified, may offer a selective evaluation of cerebellar dysfunction in such patients. Thirty-two patients with definite MS and arm tremor were evaluated (simplified Fahn tremor scale for kinetic and postural tremor, finger-to-nose test, clinical SH manoeuvre, quantitative study of the SH manoeuvre). Median severity of kinetic and postural tremor on the most disabled side was, respectively, 2 (range 0-4) and 1.5 (range 0-4). Clinical SH scores were moderately correlated to quantified SH measures (r = 0.36, P < 0.05). Kinetic and postural tremors were strongly correlated (r = 0.73, P < 0.0001) but did not correlate with clinical or quantified SH scores. Patients with bilateral tremor had higher scores for quantified SH, and a trend to higher clinical SH and finger-to-nose scores than patients with unilateral tremor. Although clinically associated, cerebellar dysfunction and tremor may be partly independent symptoms, suggesting they may relate to dysfunction of different neuronal systems. The SH manoeuvre should be part of the evaluation of MS patients considered for surgery of tremor.

Adult↗
PubMed2003

Multiple paths towards repair in multiple sclerosis.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS, affecting approximately 1/1000 individuals in the Western world. Available treatments limit CNS inflammation and strategies to repair damage in the CNS offer the potential of recovery of both tissue and function. With further fundamental knowledge developing, this area is ripe for 'translation' to clinical application.

Humans↗
PubMed2003

[The remyelination phenomenon in multiple sclerosis].

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system. Available treatments (immuno-modulators, immuno-suppressants) limit central nervous system inflammation and are only partially effective. Remyelination of naked axons becomes insufficient in most cases as the disease progresses. The reason for this repair deficit are many, including oligodendroglial, axonal and environmental factors. Understanding why remyelination fails is crucial for devising effective methods by which to enhance it.

Animals↗
PubMed2002

Ciliary neurotrophic factor (CNTF) enhances myelin formation: a novel role for CNTF and CNTF-related molecules.

In multiple sclerosis, myelin repair is generally insufficient despite the relative survival of oligodendrocytes within the plaques and the recruitment of oligodendrocyte precursors. Promoting remyelination appears to be a crucial therapeutic challenge. Using a newly developed enzymatic index of myelination, we screened different neurotrophic factors for their ability to enhance myelination. Neurotrophins [NGF, neurotrophin-3 (NT-3), NT-4/5, BDNF], glial cell line-derived neurotrophic factor (GDNF)-related factors (GDNF, neurturin), and growth factors such as PDGF-AA, FGF-2, and insulin did not increase myelinogenesis. In contrast, among factors belonging to the CNTF family, CNTF, leukemia inhibitory factor, cardiotrophin-1, and oncostatin M induced a strong promyelinating effect. We provide evidence that CNTF acts on oligodendrocytes by favoring their final maturation, and that this effect is mediated through the 130 kDa glycoprotein receptor common to the CNTF family and transduced through the Janus kinase pathway. Our results demonstrate a novel role for neurotrophic factors of the CNTF family and raise the possibility that these factors might be of therapeutic interest to promote remyelination in multiple sclerosis.

Animals↗
PubMed2002

Neurofascin is a glial receptor for the paranodin/Caspr-contactin axonal complex at the axoglial junction.

In myelinated fibers of the vertebrate nervous system, glial-ensheathing cells interact with axons at specialized adhesive junctions, the paranodal septate-like junctions. The axonal proteins paranodin/Caspr and contactin form a cis complex in the axolemma at the axoglial adhesion zone, and both are required to stabilize the junction. There has been intense speculation that an oligodendroglial isoform of the cell adhesion molecule neurofascin, NF155, expressed at the paranodal loop might be the glial receptor for the paranodin/Caspr-contactin complex, particularly since paranodin/Caspr and NF155 colocalize to ectopic sites in the CNS of the dysmyelinated mouse Shiverer mutant. We report that the extracellular domain of NF155 binds specifically to transfected cells expressing the paranodin/Caspr-contactin complex at the cell surface. This region of NF155 also binds the paranodin/Caspr-contactin complex from brain lysates in vitro. In support of the functional significance of this interaction, NF155 antibodies and the extracellular domain of NF155 inhibit myelination in myelinating cocultures, presumably by blocking the adhesive relationship between the axon and glial cell. These results demonstrate that the paranodin/Caspr-contactin complex interacts biochemically with NF155 and that this interaction is likely to be biologically relevant at the axoglial junction.

Animals↗
PubMed2002

Re-expression of PSA-NCAM by demyelinated axons: an inhibitor of remyelination in multiple sclerosis?

Multiple sclerosis is affecting approximately 1 out of every 1000 individuals in the western world. After axons are denuded of myelin in the early stages of the disease, remyelination occurs, but eventually this process fails, and permanent disability is the result. During development, the polysialylated form of the neural cell adhesion molecule NCAM, PSA-NCAM, is expressed at the axonal surface and acts as a negative regulator of myelination, presumably by preventing myelin-forming cells from attaching to the axon. Removal of PSA-NCAM from the axonal surface is a prerequisite for the initiation of myelination. We questioned whether, in multiple sclerosis, re-expression of PSA-NCAM by axons could occur, and therefore account for the failure of remyelination. Forty multiple sclerosis lesions from 24 different post-mortem multiple sclerosis cases were selected by histological methods and analysed by immunohistochemistry. Demyelinated lesions and partially remyelinated lesions (shadow plaques) were studied. Controls consisted of post-mortem brain tissue from patients with amyotrophic lateral sclerosis and without neurological disease. We showed that PSA-NCAM, normally absent from adult brain, is re-expressed on demyelinated axons in the plaques. Within shadow plaques, remyelinated axons do not express PSA-NCAM. Re-expression of PSA-NCAM could act as an inhibitor of remyelination and participate in disease progression in multiple sclerosis.

Axons↗