S. Nischwitz

Evidence for VAV2 and ZNF433 as susceptibility genes for multiple sclerosis

In a genome wide association study consisting of 592 German multiple sclerosis (MS) patients and 825 controls we were able to replicate the association of the HLA region with MS independently of previous case control studies. No SNPs outside the HLA region reached a genome wide level of significance. Nevertheless, we found suggestive evidence for an association of MS with variants in two new genes, the VAV2 gene and the gene for ZNF433.

Risk conferring genes in multiple sclerosis

Multiple sclerosis (MS) is characterized by inflammation, axonal and oligodendrocyte pathology and progressive neurological disability. Epidemiologic data indicate that MS may be caused by interplay of genetic and environmental factors. Large samples collected in cooperative efforts and new technologies such as high throughput single nucleotide polymorphism (SNP) genotyping allowed recently to discover non‐HLA genes associated with MS susceptibility that are mostly involved in the immune response. In addition, several studies indicate an effect of genetic variations on disease onset, progression and response to therapy. However, the polymorphisms discovered so far explain the genetic variation in MS only in part and are mostly common variants that have only low impact on MS susceptibility. Functional studies are required to validate the importance of the newly identified SNPs. Taking into account the interplay of genetic and environmental factors a combination of genome wide genotyping including HLA‐typing and genome wide expression profiling as well as a collection on relevant or putatively relevant environmental factors in patients well characterized clinically and by MRI is a promising way to identify new disease relevant biomarkers.

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation.

Genome-wide study in Germans identifies four novel multiple sclerosis risk genes and confirms already known gene loci. We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis.

More CLEC16A gene variants associated with multiple sclerosis

Nischwitz S, Cepok S, Kroner A, Wolf C, Knop M, Müller‐Sarnowski F, Pfister H, Rieckmann P, Hemmer B, Ising M, Uhr M, Bettecken T, Holsboer F, Müller‐Myhsok B, Weber F. More CLEC16A gene variants associated with multiple sclerosis.
Acta Neurol Scand: 2011: 123: 400–406.
© 2010 John Wiley & Sons A/S.

Interferon β‐1a reduces increased interleukin‐16 levels in multiple sclerosis patients

There is convergent evidence for an important role of interleukin‐16 (IL‐16) in the pathogenesis of multiple sclerosis (MS). IL‐16 serves as a chemoattractant for different immune cells that are involved in developing lesions. Here, we compared IL‐16 levels of MS patients and controls and addressed the long‐term effect of IFN‐β, the most common immunomodulatory MS therapy, on IL‐16 serum levels in MS patients over 2 years. Beyond this, we analysed the expression of IL‐16 in two CD4+ T‐cell subsets, Th1 and Th17 cells, which are important autoimmune mediators and affected by IFN‐β treatment, derived from myelin‐specific T‐cell transgenic mice.

Successful Replication of GWAS Hits for Multiple Sclerosis in 10,000 Germans Using the Exome Array.

Genome‐wide association studies (GWAS) successfully identified various chromosomal regions to be associated with multiple sclerosis (MS). The primary aim of this study was to replicate reported associations from GWAS using an exome array in a large German study. German MS cases (n = 4,476) and German controls (n = 5,714) were genotyped using the Illumina HumanExome v1‐Chip. Genotype calling was performed with the Illumina Genome StudioTM Genotyping Module, followed by zCall. Single‐nucleotide polymorphisms (SNPs) in seven regions outside the human leukocyte antigen (HLA) region showed genome‐wide significant associations with MS (P values < 5 × 10−8). These associations have been reported previously. In addition, SNPs in three previously reported regions outside the HLA region yielded P values < 10−5. The effect of nine SNPs in the HLA region remained (P < 10−5) after adjustment for other significant SNPs in the HLA region. All of these findings have been reported before or are driven by known risk loci. In summary, findings from previous GWAS for MS could be successfully replicated. We conclude that the regions identified in previous GWAS are also associated in the German population. This reassures the need for detailed investigations of the functional mechanisms underlying the replicated associations.

MS susceptibility is not affected by single nucleotide polymorphisms in the MMP9 gene

Matrix metalloproteinase 9 (MMP9) plays an important role in the pathogenesis of multiple sclerosis (MS). However, the impact of genetic variants affecting MMP9 on MS susceptibility is still in debate. We could not detect an association of MMP9 SNPs with MS on a genome-wide significance level by SNP genotyping, followed by imputation of SNPs within a region stretching 2Mbp up- and down-stream of MMP9. Rs6073751, located within WFDC2, was found associated with MS most strongly. Rs3918242, associated with MS according to previous reports, showed nominal significance only. Meta-analysis of our own and published data did not confirm this effect.

MALDI imaging mass spectrometry Analysis - A new approach for protein mapping in multiple sclerosis brain lesions

Multiple sclerosis is a disease of the central nervous system characterized by recurrent inflammatory demyelinating lesions in the early disease stage. Lesion formation and mechanisms leading to lesion remyelination are not fully understood. Matrix Assisted Laser Desorption Ionisation Mass Spectrometry imaging (MALDI-IMS) is a technology which analyses proteins and peptides in tissue, preserves their spatial localization, and generates molecular maps within the tissue section. In a pilot study we employed MALDI imaging mass spectrometry to profile and identify peptides and proteins expressed in normal-appearing white matter, grey matter and multiple sclerosis brain lesions with different extents of remyelination. The unsupervised clustering analysis of the mass spectra generated images which reflected the tissue section morphology in luxol fast blue stain and in myelin basic protein immunohistochemistry. Lesions with low remyelination extent were defined by compounds with molecular weight smaller than 5300Da, while more completely remyelinated lesions showed compounds with molecular weights greater than 15,200Da. An in-depth analysis of the mass spectra enabled the detection of cortical lesions which were not seen by routine luxol fast blue histology. An ion mass, mainly distributed at the rim of multiple sclerosis lesions, was identified by liquid chromatography and tandem mass spectrometry as thymosin beta-4, a protein known to be involved in cell migration and in restorative processes. The ion mass of thymosin beta-4 was profiled by MALDI imaging mass spectrometry in brain slides of 12 multiple sclerosis patients and validated by immunohistochemical analysis. In summary, our results demonstrate the ability of the MALDI-IMS technology to map proteins within the brain parenchyma and multiple sclerosis lesions and to identify potential markers involved in multiple sclerosis pathogenesis and/or remyelination.

USPIO-gestützte Charakterisierung der weißen Substanz bei MS

Die MRT kann durch neuere Sequenztechniken, Kontrastmittel und Analysetechniken zur Aufklärung der pathogenetischen Vorgänge der MS beitragen, die bezüglich Läsionshistopathologie und klinischem Verlauf heterogen sind. Ein wichtiger MRT-Index für den Krankheitsprogress sind wiederholt nachweisbare BlutHirn-Schranken-Störungen, die durch Gd dargestellt werden. Chronische Entzündungsund/oder Reparaturvorgänge können bisher jedoch nur eingeschränkt erfasst werden. USPIO sind eine viel versprechende Technik, um Makrophagen zu kontrastieren. In dieser Studie werden verschiedene Aspekte des USPIO-Aufnahmeverhaltens bei Gd-floriden und -nichtfloriden Patienten untersucht.