Mathias Mäurer

CNTF is a major protective factor in demyelinating CNS disease: A neurotrophic cytokine as modulator in neuroinflammation

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). So far, immunological mechanisms responsible for demyelination have been the focus of interest. However, mechanisms regulating axon maintenance as well as glial precursor-cell proliferation and oligodendrocyte survival might also influence disease outcome. The cytokine ciliary neurotrophic factor (CNTF), which was originally identified as a survival factor for isolated neurons, promotes differentiation, maturation and survival of oligodendrocytes. To investigate the role of endogenous CNTF in inflammatory demyelinating disease, we studied myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in CNTF-deficient and wild-type C57BL/6 mice. Disease was more severe in CNTF-deficient mice and recovery was poor, with a 60% decrease in the number of proliferating oligodendrocyte precursor cells (OPCs) and a more than 50% increase in the rate of oligodendrocyte apoptosis. In addition, vacuolar dystrophy of myelin and axonal damage were more severe in CNTF-deficient mice. These specific pathological features could be prevented by treatment with an antiserum against tumor necrosis factor-α, suggesting that endogenous CNTF may counterbalance this effect of TNF-α (ref. 7). Here we identify a factor that modulates, in an inflammatory environment, glial cell survival and is an outcome determinant of EAE.

A polymorphism in the human cytotoxic T-lymphocyte antigen 4 ( CTLA4) gene (exon 1 +49) alters T-cell activation.

Abstract. The cytotoxic T-lymphocyte antigen 4 (CTLA4) is an important modifier of T-cell activation with down-regulatory properties upon B7 engagement. An allelic polymorphism in exon 1 of the CTLA4 gene coding for the peptide leader sequence of CTLA4 was recently described. This polymorphism was detected in association with several autoimmune diseases. In this study, we investigated the functional impact of the CTLA4 exon 1 +49 A/G dimorphism on T-cell activation and cellular localization. We examined the T-cell response from healthy donors either homozygous for A or G at position +49 of the exon 1. Under suboptimal stimulation conditions we found a greater proliferative response of cells from donors homozygous for G at position +49. FACS analysis of CTLA4 expression revealed a reduced up-regulation of CTLA4 from G/G donors upon T-cell activation, if compared with wild-type cells. Intracellular CTLA4 distribution demonstrated qualitatively different staining patterns between the two genotypes as determined using confocal fluorescence microscopy. Our results suggest that the G allele at position +49 of exon 1 affects the CTLA4-driven down-regulation of T-cell activation and may be an important factor in the pathogenesis of autoimmune diseases.

A PD‐1 polymorphism is associated with disease progression in multiple sclerosis

T cells are considered to play a pivotal role in orchestrating the self‐reactive immune responses in multiple sclerosis (MS). Programmed death 1 (PD‐1) is a member of the B7/CD28 superfamily of costimulatory molecules exerting inhibitory functions on T cells. Recently, an intronic 7146G/A polymorphism within the PD‐1 gene was described and suggested to be associated with autoimmunity. We investigated whether this genetic polymorphism is a genetic modifier for risk and progression of MS. Blood samples from 939 German MS patients (mean age, 39 years; range, 13–71; 566 patients [60%] with relapsing‐remitting MS, 279 (30%) with secondary, and 94 (10%) with primary progressive MS) and 272 healthy white controls were tested. Genotyping was performed by polymerase chain reaction and restriction enzyme digestion; results were confirmed by automatic sequencing. A significant association of the mutated allele with a progressive disease course was detected (44% 7146G vs 56% 7146A, χ2 p = 0.002). Consequences of the PD‐1 mutation for T‐cell function were assessed ex vivo in some patients using microsphere‐stimulated peripheral blood lymphocytes and purified CD4 cells. Importantly, PD‐1–mediated inhibition of T‐cell cytokine secretion (interferon‐γ) is impaired in patients carrying the PD‐1 polymorphism. In conclusion, our data suggest that PD‐1 polymorphism is a genetic modifier of the progression of MS, possibly through inducing a partial defect in PD‐1–mediated inhibition of T‐cell activation. Ann Neurol 2005

Molecular profiling of angiogenesis with targeted ultrasound imaging: early assessment of antiangiogenic therapy effects

Molecular ultrasound is capable of elucidating the expression of angiogenic markers in vivo. However, the capability of the method for volumetric “multitarget quantification” and for the assessment of antiangiogenic therapy response has rather been investigated. Therefore, we generated cyanoacrylate microbubbles linked to vascular endothelial growth factor receptor 2 (VEGFR2) and αvβ3 integrin binding ligands and quantified their accumulation in squamous cell carcinoma xenografts (HaCaT-ras-A-5RT3) in mice with the quantitative volumetric ultrasound scanning technique, sensitive particle acoustic quantification. Specificity of VEGFR2 and αvβ3 integrin binding microbubbles was shown, and changes in marker expression during matrix metalloproteinase inhibitor treatment were investigated. In tumors, accumulation of targeted microbubbles was significantly higher compared with nonspecific ones and could be inhibited competitively by addition of the free ligand in excess. Also, multimarker imaging could successfully be done during the same imaging session. Molecular ultrasound further indicated a significant increase of VEGFR2 and αvβ3 integrin expression during tumor growth and a considerable decrease in both marker densities after matrix metalloproteinase inhibitor treatment. Histologic data suggested that the increasing VEGFR2 and αvβ3 integrin concentrations in tumors during growth are related to an up-regulation of its expression by the endothelial cells, whereas its decrease under therapy is more related to the decreasing relative vessel density. In conclusion, targeted ultrasound appears feasible for the longitudinal molecular profiling of tumor angiogenesis and for the sensitive assessment of therapy effects in vivo. [Mol Cancer Ther 2008;7(1):101–9]

Measurement of Cerebral Blood Flow Volume by Extracranial Sonography

Measurement of global cerebral blood flow (CBF) using extracranial duplex sonography has been described, but normal values are still lacking. In 85 healthy adults (median age 43.4 years, range 20 to 80 years), CBF was determined by duplex sonographic examination of both internal carotid arteries and vertebral arteries. The mean global CBF was 630 ± 97 mL/min. Global CBF declined with age; sex did not influence the total CBF. When measurements were repeated, the intraindividual variability was low. This noninvasive sonographic measurement of CBF is reproducible, and values correspond closely to those obtained with positron emission tomography and magnetic resonance imaging.

CTLA4 exon 1 dimorphism is associated with primary progressive multiple sclerosis

The cytotoxic T-lymphocyte antigen 4 (CTLA4) is an important modifier of T-cell activation with down-regulatory properties upon B7 engagement. We investigated the association of the CTLA4 A/G dimorphism in exon 1 (+49) with disease susceptibility, disease course and severity. No differences in the allelic distribution of the G(49) allele between multiple sclerosis (MS) patients and the control group was found. However, the G(49) allele occurred in a significant higher percentage of patients with primary progressive MS compared to patients with bout onset of disease. The results suggest that dysregulation of CTLA4-driven down-regulation of T-cell function due a genetic dimorphism in exon 1 may be involved in the pathogenesis of different MS disease subtypes.

Animal models of immune-mediated neuropathies

Purpose of reviewThis article gives an overview on animal models for immune-mediated demyelinating disorders of the peripheral nervous system. As insight into human disease is mainly based on biopsy material and ex-vivo analysis, an understanding of the pathogenetic mechanism of these complex and heterogeneous disorders is mainly based on animal models. Recent findingsBesides experimental autoimmune neuritis in rats, recent efforts to establish this model in mice are discussed. In addition, models for spontaneous autoimmune neuropathies and secondary immune reactions in degenerative disorders of the peripheral nervous system are reviewed. SummaryRecently described animal models offer the possibility to analyse the complex interaction of genetic and immunological factors. The entire panel of animal models for immune-mediated disorders of the peripheral nervous system provides a rational basis for studying the mechanisms of pathogenesis and new immunotherapeutic strategies for human autoimmune demyelinating neuropathies.

Role of immune cells in animal models for inherited neuropathies: facts and visions

Mice heterozygously deficient in the peripheral myelin adhesion molecule P0 (P0+/− mice) are models for some forms of Charcot–Marie–Tooth (CMT) neuropathies. In addition to the characteristic hallmarks of demyelination, elevated numbers of CD8‐positive T‐lymphocytes and F4/80‐positive macrophages are striking features in the nerves of these mice. These immune cells increase in number with age and progress of demyelination, suggesting that they might be functionally related to myelin damage. In order to investigate the pathogenetic role of lymphocytes, the myelin mutants were cross‐bred with recombination activating gene 1 (RAG‐1)‐deficient mice, which lack mature T‐ and B‐lymphocytes. The immunodeficient myelin mutants showed a less severe myelin degeneration. The beneficial effect of lymphocyte‐deficiency was reversible, since demyelination worsened in immunodeficient myelin‐mutants when reconstituted with bone marrow from wild‐type mice. Ultrastructural analysis revealed macrophages in close apposition to myelin and demyelinated axons. We therefore cross‐bred the P0+/− mice with spontaneous osteopetrotic (op) mutants deficient in the macrophage colony‐stimulating factor (M‐CSF), hence displaying impaired macrophage activation. In the corresponding double mutants the numbers of macrophages were not elevated in the peripheral nerves, and the demyelinating phenotype was less severe than in the genuine P0+/− mice, demonstrating that macrophages are also functionally involved in the pathogenesis of genetically mediated demyelination. We also examined other models for inherited neuropathies for a possible involvement of immune cells. We chose mice deficient in the gap junction component connexin 32, a model for the X‐linked form of CMT. Similar to P0‐deficient mice, T‐lymphocytes and macrophages were elevated and macrophages showed a close apposition to degenerating myelin. We conclude that the involvement of T‐lymphocytes and macrophages is a common pathogenetic feature in various forms of slowly progressive inherited neuropathies.

Genetic variation at position -1082 of the interleukin 10 (IL10) promotor and the outcome of multiple sclerosis.

Interleukin-10 is a potent immunomodulatory cytokine with possible implications for the pathogenesis of multiple sclerosis. Increased IL10 mRNA expression is associated with stable disease. The interleukin 10 gene is highly polymorphic and certain haplotypes result in differential interleukin-10 expression. The presence of guanine instead of adenine at position -1082 in the IL10 promotor was shown to result in a higher IL10 production. We analysed this diallelic polymorphism in patients with multiple sclerosis but did not find any association between a certain -1082 IL10 genotype and susceptibility to or severity of multiple sclerosis.

Multiple sclerosis relapses are not associated with exercise

Since multiple sclerosis (MS) often affects physically active young individuals, it is important to know if exercise can result in increased disease activity. Therefore we used a self-report questionnaire to examine the relationship of different levels of sports activity and relapses in 632 patients with MS. In order to analyse whether subjective recall might have biased the results, we performed, in a subgroup of our sample, an objective assessment of clinical data and physical fitness parameters. We were unable to find any association between sports activity and clinical relapses in either of the two analyses. The group with highest activity even shows the lowermost mean values, standard deviations and range concerning the number of relapses. Our data suggest that physical activity has no significant influence on clinical disease activity.