Lack of association with the CD28/CTLA4/ICOS gene region among Norwegian multiple sclerosis patients

The Role of Cytotoxic T-Lymphocyte Antigen 4 in the Pathogenesis of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disorder of the central nervous system that presents heterogeneous clinical manifestations and course. It has been shown that different immune checkpoints, including Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4), can be involved in the pathogenesis of MS. CTLA-4 is a critical regulator of T-cell homeostasis and self-tolerance and represents a key inhibitor of autoimmunity. In this scopingreview, we resume the current preclinical and clinical studies investigating the role of CTLA-4 in MS with different approaches. While some of these studies assessed the expression levels of CTLA-4 on T cells by comparing MS patients with healthy controls, others focused on the evaluation of the effects of common MS therapies on CTLA-4 modulation or on the study of the CTLA-4 blockade or deficiency in experimental autoimmune encephalomyelitis models. Moreover, other studies in this field aimed to discover if the CTLA-4 gene might be involved in the predisposition to MS, whereas others evaluated the effects of treatment with CTLA4-Ig in MS. Although these results are of great interest, they are often conflicting. Therefore, further studies are needed to reveal the exact mechanisms underlying the action of a crucial immune checkpoint such as CTLA-4 in MS to identify novel immunotherapeutic strategies for MS patients.

Correlation between CTLA-4 gene rs221775A>G single nucleotide polymorphism and multiple sclerosis susceptibility. A meta-analysis

OBJECTIVE

The aim of this meta-analysis was to undertake a meta-analysis to evaluate the correlation between cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) gene rs221775 A>G single nucleotide polymorphism and the susceptibility of multiple sclerosis (MS) susceptibility.

METHOD

Published manuscripts about CTLA-4 gene rs221775A>G single nucleotide polymorphism and multiple sclerosis susceptibility were searched in the computerized bibliographic searches of Pubmed Embase and China National Knowledge Infrastructure (CNKI). Potential studies were screened and data for 5025 MS patients and 4706 controls from 20 publications were included. The association between CTLA-4 gene rs221775A>G single nucleotide polymorphism and multiple sclerosis susceptibility were demonstrated by odds ratio (OR) and 95% confidence interval (95%CI).

RESULTS

The pooled results showed no significant association between CTLA-4 gene rs221775A>G single nucleotide polymorphism and multiple sclerosis susceptibility for dominant genetic model [OR=1.02, 95%CI:0.90~1.05, (P=0.80)], homozygous genetic model [OR=0.85,95%CI:0.71 ~1.03,(P=0.10)] and recessive genetic model [OR=0.99,95% CI:0.89~1.10,(P=0.90)].

CONCLUSION

With current evidence, CTLA-4 gene rs221775A>G single nucleotide polymorphism had no association with the susceptibility of multiple sclerosis.

CTLA-4 gene and the susceptibility of multiple sclerosis: an updated meta-analysis study including 12,916 cases and 15,455 controls

Abstract Cytotoxic T-lymphocyte antigen-4 (CTLA-4) is a cell surface molecule involved in the regulation of T cells. Single-nucleotide polymorphisms (SNPs) of CTLA-4 gene are known to be associated with susceptibility to several autoimmune diseases, including multiple sclerosis (MS). This study aimed to evaluate the association between CTLA-4 and the risk of MS. Comprehensive meta-analysis was applied to case-control studies of the association between MS and CTLA-4 to assess the joint evidence for the association, the influence of individual studies, and evidence for publication bias. The authors searched PubMed, MEDLINE, Cochrane Library, and reference lists of relevant studies to September 2013. In all, the allele or genotype analysis showed no significant association between + 49A/G, - 318C/T, or CT60A/G and MS. And the subgroups of the three polymorphisms divided into Americas, Europe, and Asia showed no significant association with MS. The sensitivity analysis or publication bias analysis showed no significance. In conclusion, this comprehensive meta-analysis suggested that + 49A/G, - 318C/T, or CT60A/G polymorphism, either in total analysis or in subgroup analyses, has no significant association with MS disease.

Genetics of primary progressive multiple sclerosis

Multiple sclerosis (MS) patients are classified as either having relapsing onset or progressive onset disease, also known as primary progressive MS (PPMS). Relative to relapsing onset patients, PPMS patients are older at disease onset, are equally likely to be men or women, and have more rapid accumulation of disability that does not respond well to treatments used in relapsing onset MS. Although estimates vary, 5-15% of all MS patients have a PPMS disease course. Genetic variance is a proposed determinant of MS disease course. If distinct genes associated with PPMS were identified study of these genes might lead to an understanding of the biology underlying disease progression and neural degeneration that are the hallmarks of PPMS. These genes and their biological pathways might also represent therapeutic targets. This chapter systematically reviews the PPMS genetic literature. Despite the intuitively appealing notion that differences between PPMS and relapsing onset MS are due to genetics, definite differences associated with these phenotypes at the major histocompatibility complex or elsewhere in the genome have not been found. Recent large-scale genome wide screens identified multiple genes associated with MS susceptibility outside the MHC. The genetic variants identified thus far make only weak individual contributions to MS susceptibility. If the genetic effects that contribute to the differences between PPMS and relapsing MS are similar in magnitude to those that distinguish MS from healthy controls then, given the relative scarcity of the PPMS phenotype, very large datasets will be needed to identify PPMS associated genes. International collaborative efforts could provide the means to identify such genes. Alternately, it is possible that factors other than genetics underlie the differences between these clinical phenotypes.

Plasma sCD28, sCTLA-4 levels in neuromyelitis optica and multiple sclerosis during relapse

BACKGROUND

Soluble forms of CD28 (sCD28) and CTLA-4 (sCTLA-4) were associated with many autoimmune diseases like Sjögren's syndrome, systemic lupus erythematosus, asthma, and autoimmune myasthenia gravis. However, sCD28 and sCTLA-4 in neuromyelitis optica (NMO) and multiple sclerosis (MS) patients were less studied.

OBJECTIVE

To measure the plasma sCD28, sCTLA-4 in NMO and MS patients, and investigate whether sCD28 and sCTLA-4 possible use as sensitive biomarkers for diseases activity.

METHODS

Plasma concentrations of sCD28, sCTLA-4 were measured by an enzyme-linked immunosorbent assay (ELISA) in NMO (n=22), MS (n=21) patients and controls (n=18).

RESULTS

The concentration of sCD28 levels were higher in the inflammatory demyelinating diseases cohort compared with the controls (NMO, p=0.034; MS, p=0.026) and the levels of sCD28 were slightly higher in NMO compared with MS. The sCTLA-4 levels were lower in the MS subgroup compared with the controls (p=0.032). Both sCD28 and sCTLA-4 did not show any correlation with EDSS score in NMO and MS patients.

CONCLUSIONS

Our study revealed for the first time that the levels of increased plasma sCD28 and decreased plasma sCTLA-4 in NMO and MS patients, but had little correlation with clinical presentations.

The CTLA-4 gene polymorphisms are associated with CTLA-4 protein expression levels in multiple sclerosis patients and with susceptibility to disease

Cytotoxic T-lymphocyte antigen-4 (CTLA-4) is an important molecule in the down-regulation of T-cell activation. A study was undertaken to evaluate the association of the CTLA-4 gene polymorphisms -319C/T, +49A/G, (AT)(n), CT60A/G and Jo31G/T with the levels of membrane CTLA-4 (mCTLA-4) and cytoplasmic CTLA-4 (cCTLA-4) in CD4(+) T lymphocytes from patients with multiple sclerosis (MS) and with susceptibility to MS, and the course of the disease. It was found that the Jo31GG and CT60GG genotypes were associated with decreased mean fluorescence intensity (MFI) of total CTLA-4 (mCTLA-4 + cCTLA-4) molecules in CD4(+) T cells from both relapsing-remitting (RR) and secondary progressive (SP) MS patients compared with others. Consequently, possessing the Jo31G allele and/or the CT60G allele were associated with susceptibility to MS. The percentages of cells expressing mCTLA-4 and cCTLA-4 in RR patients were higher in carriers of the alleles non-predisposing to MS (namely CT60A and Jo31T), but the percentages of corresponding cells were unexpectedly significantly lower in SP patients than in RR patients. Increased risk of paresthesia and pyramidal signs as a first manifestation of disease, and earlier transition to the SP form in those patients, was also noted. It is hypothesized that the decreasing frequencies of cells expressing immunosuppressive mCTLA-4 and cCTLA-4 in carriers of alleles non-predisposing to MS (i.e. CT60A and Jo31T) may lead to inadequate down-regulation of ongoing T-cell responses in these patients and, as a consequence, earlier progression of disease from the RR form to the SP form.

Genomic regulation of CTLA4 and multiple sclerosis

The cytotoxic T lymphocyte antigen 4 gene (CTLA4) is a critical regulator of T-cell activation and it is an important therapeutic target for cancer and autoimmune diseases. Here, we analyzed the genomic regulation of CTLA4 gene expression in order to identify single nucleotide polymorphisms (SNPs) that affect its expression and splicing, and to assess their association with Multiple Sclerosis (MS). We analyzed 152 healthy subjects and 146 patients with MS, of which 52 controls and 51 patients were used for gene expression analysis. We genotyped 17 SNPs in the CTLA4 gene using the SNaPshot Multiplex Kit, and in addition gene expression of the soluble (sCTLA4) and full length (flCTLA4) isoforms was quantified by real-time PCR, while protein levels of sCTLA4 were measured by ELISA. We found that the SNPs at -1577, +6230, +10242, +10717 and +12310 influence CTLA4 expression and the combination of the -1577 GG and +6230 GG genotypes provokes the strongest decrease in CTLA4 gene expression. We found that the SNP at -658 only acted as a regulatory SNP in patients with MS, suggesting the existence of epigenetic changes due to this disease. We also identified a decrease in CTLA4 gene expression levels in patients receiving chemotherapy, although no association was observed between MS and any of the polymorphisms studied. In conclusion, we have identified several SNPs in the CTLA4 gene and studied their influence on its genetic regulation. The involvement of CTLA4 in the pathogenesis of MS may be subtle and related to the functional changes in its pathway rather than predisposing genetic polymorphisms.

Scanning for DNA variants by denaturant capillary electrophoresis

Analysis and detection of DNA variation is important in any field of biology. Hence, numerous methods have been developed to analyze DNA. A simple yet effective way of analyzing DNA is by denaturant capillary electrophoresis (DCE). The method is in theory applicable to 95% of the human genome. The method involves three steps; fragment design, PCR amplification and allele separation. The allele separation can in principle be performed with any DNA capillary sequencing instrument.

Analysis of mutational spectra by denaturing capillary electrophoresis

The point mutational spectrum over nearly any 75- to 250-bp DNA sequence isolated from cells, tissues or large populations may be discovered using denaturing capillary electrophoresis (DCE). A modification of the standard DCE method that uses cycling temperature (e.g., +/-5 degrees C), CyDCE, permits optimal resolution of mutant sequences using computer-defined target sequences without preliminary optimization experiments. The protocol consists of three steps: computer design of target sequence including polymerase chain reaction (PCR) primers, high-fidelity DNA amplification by PCR and mutant sequence separation by CyDCE and takes about 6 h. DCE and CyDCE have been used to define quantitative point mutational spectra relating to errors of DNA polymerases, human cells in development and carcinogenesis, common gene-disease associations and microbial populations. Detection limits are about 5 x 10(-3) (mutants copies/total copies) but can be as low as 10(-6) (mutants copies/total copies) when DCE is used in combination with fraction collection for mutant enrichment. No other technological approach for unknown mutant detection and enumeration offers the sensitivity, generality and efficiency of the approach described herein.

Recent advances in genetic analysis of multiple sclerosis: genetic associations and therapeutic implications

Epidemiological studies have confirmed that genetic factors are a key component in the pathogenesis of multiple sclerosis (MS) and that those determining MS susceptibility have been extensively studied. Many papers have been published regarding the heritable differences useful in genetic studies; these include variations in DNA, such as single-nucleotide polymorphisms, microsatellites and insertion/deletion polymorphisms. However, to date, among other regions, HLA is the only region confirmed to possess genes that determine MS susceptibility. In this article, we review the progress during the last 5 years in the studies on the susceptibility genes and the pharmacogenetics of MS. Newer techniques and methods of analysis will hopefully result in better screening of individuals who are at highest risk and novel treatments.

Multiple sclerosis and the CTLA4 autoimmunity polymorphism CT60: no association in patients from Germany, Hungary and Poland

Polymorphisms in the CTLA4 gene region have been associated with susceptibility to autoimmune diseases. The recently described single nucleotide polymorphism CT60, located in the 3' untranslated region of CTLA4 is associated with Graves' disease, thyroiditis, autoimmune diabetes and other autoimmune diseases. A case-control association study was conducted in German, Hungarian and Polish multiple sclerosis (MS) patients and regional control individuals for the CTLA4 CT60 and + 49A/G polymorphisms. No significant association of these polymorphisms or respective haplotypes with MS was found. No association of CT60 genotypes with T cell expression of ICOS and CTLA-4 after in vitro stimulation was detected. Multiple Sclerosis 2008; 14: 153—158. http://msj.sagepub.com

No evidence for association of CTLA-4 gene polymorphisms with the risk of developing multiple sclerosis: a meta-analysis

We conducted a meta-analysis concerning the association of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) gene polymorphisms with the risk of developing multiple sclerosis (MS). We identified 18 eligible studies summarizing information about 3375 MS cases and 2930 healthy controls. Two polymorphisms were of interest: the exon 1 +49 A/G polymorphism (in 18 studies) and the promoter-318 C/T polymorphism (in 10 studies). Using random-effects methods we found no evidence for association of the various contrasts of genotypes (or allele frequencies) with the disease. There was significant between-studies heterogeneity that could not be explained by the ethnicity of the populations studied or by other summary measures (gender, disease course, latitude). The major finding of the meta-analysis, apart from the lack of an overall association, consists of detecting a significant time trend of the OR for the contrast of GA versus GG+AA genotypes of the exon 1 +49 A/G polymorphism. In particular, using cumulative meta-analysis we found that the large number of conflicting results on the subject was triggered by the early appearance of a highly significant published result (a study that indicated a significant association of the genotype with the disease).

CTLA4 gene polymorphisms and multiple sclerosis in Northern Ireland

Four CTLA4 polymorphisms were investigated in a Northern Irish collection of relapsing-remitting (RR) and primary-progressive (PP) multiple sclerosis (MS) patients. The CTLA4 promoter (-318 C/T), exon 1 (+49 A/G) and intergenic CT60 SNPs, as well as a microsatellite found in the 3' UTR (AT(n)) were analysed in 246 RRMS, 84 PPMS and 158 healthy controls. The A allele of the exon 1 +49 A/G SNP (OR=1.36; 95% CI=1.11-1.81; P=0.038), and more so the AA genotype (OR=1.70; 95% CI=1.11-2.60; P=0.015) were associated with RR, but not PPMS. In the PPMS population, overall allele distribution of the AT(n) microsatellite was significantly different from that in the healthy controls. We did not find any association with the promoter (-318 C/T) or intergenic CT60 SNPs in either of the disease cohorts. In concordance with several recent studies, we detected a trend toward higher carriage rates of the +49 G allele in PP vs RR MS patients (66.7% vs 58.9%), though this was not significant. Our data highlight the CTLA4 +49 A/G and 3'UTR polymorphisms as potential modifiers of disease course in MS.

ICOS gene haplotypes correlate with IL10 secretion and multiple sclerosis evolution

Human ICOS is a T cell costimulatory molecule supporting IL10 secretion. A pilot study investigating variations of the ICOS gene 3'UTR detected 8 polymorphisms forming three haplotypes (A, B, C). Haplotype-A and -C displayed the highest difference. Activated T cells from healthy AA homozygotes expressed significantly less ICOS and secreted more IL10 than AC heterozygotes, whereas AB heterozygotes displayed intermediate levels. Analysis of 441 multiple sclerosis patients and 793 controls showed that frequency of AA homozygosity was significantly lower in MS patients with relapsing-remitting onset (N=416) than in controls (OR=0.70). Moreover, AA patients with relapsing-remitting onset had lower relapse rate and multiple sclerosis severity score than non-AA patients.

Genetics in multiple sclerosis: past and future perspectives

The enormous development in the field of molecular genetics during the last decades has lead to optimism concerning the possibilities for identifying the causes of multiple sclerosis (MS) through genetic studies. However, we have learned that dense mapping of large sample sets is needed, which only can be achieved through large collaborative studies. The contribution from each yet unidentified gene is probably weaker than that of the well established human leukocyte antigen association. The ultimate goal of the search for susceptibility genes in MS is to develop diagnostic tools and better treatments that can prevent or reduce the development of symptoms of this often devastating disease.

B7RP-1-ICOS interactions are required for optimal infection-induced expansion of CD4+ Th1 and Th2 responses

Although initial reports linked the costimulatory molecule ICOS preferentially with the development of Th2 cells, there is evidence that it is not required for protective type 2 immunity to helminths and that it contributes to Th1 and Th2 responses to other parasites. To address the role of ICOS in the development of infection-induced polarized Th cells, ICOS(-/-) mice were infected with Trichuris muris or Toxoplasma gondii. Wild-type mice challenged with T. muris developed Th2 responses and expelled these helminths by day 18 postinfection, whereas ICOS(-/-) mice failed to clear worms and produced reduced levels of type 2 cytokines. However, by day 35 postinfection, ICOS(-/-) mice were able to mount an effective Th2 response and worms were expelled. This delay in protective immunity was associated with a defect in infection-induced increases in the number of activated and proliferating CD4+ T cells. Similarly, following challenge with T. gondii ICOS was required for optimal proliferation by CD4+ T cells. However, the reduced number of activated CD4+ T cells and associated defect in the production of IFN-gamma did not result in increased susceptibility to T. gondii, but rather resulted in decreased CNS pathology during the chronic phase of this infection. Taken together, these data are consistent with a model in which ICOS is not involved in dictating polarity of the Th response but rather regulates the expansion of these subsets.

Evaluation of sieving matrices used to separate alleles by cycling temperature capillary electrophoresis

Denaturing CE (DCE) is a powerful tool for analysis of DNA variation. The development of commercial multi-CE instruments allows large-scale studies of DNA variation (many samples and many fragments). However, the cost of consumables like capillary arrays and sieving matrix might limit the use of DCE in such studies. Thus, we have tested 72 different in-house formulated sieving matrices' ability to suppress EOF and separate PCR-amplified alleles with the DCE variant, cycling temperature CE (CTCE). The data herein demonstrate that alleles can be baseline-separated by use of PVP and poly(N,N-dimethyl acrylamide) polymers at various percentages and pH. Allele separation by CTCE is matrix-independent and consequently applicable to any capillary instrument used for DNA separation. Formulation of sieving matrix for CTCE was done by dissolving appropriate amount of polymer powder into the running buffers. Allele separation was observed at different pH (7.5-8.5), concentrations and molecular size of the polymer, without compromising the separation and reproducibility. Finally, the cost reduction of homemade matrices is more than 1000-fold as compared to commercial sieving matrices.

Coding region polymorphisms in T cell signal transduction genes. Prevalence and association to development of multiple sclerosis

We systematically assessed 53 genes involved in T cell signaling, among which 72 SNPs in 32 genes were reported in databases as causing non-synonymous amino acid substitutions. Screening of 41 of these SNPs in DNA pools from 4000 Norwegian controls showed that only 12 SNPs (29%) were polymorphic. These were tested for association to MS in DNA pools from 364 Norwegian MS patients. To eliminate sources of variance introduced by DNA pooling, the SNPs in the best-ranked PLCG1 as well as the PTPN22 gene were thereafter genotyped in individual MS and control samples, however, without finding evidence for association to MS.

The Norwegian Multiple Sclerosis National Competence Centre and National Multiple Sclerosis registry -- a resource for clinical practice and research

The Norwegian Multiple Sclerosis National Competence Centre was established at the Department of Neurology, Haukeland University Hospital, Bergen in 1996. Promotion of research, supervision and education of doctors and other health care professionals in Norway are the main responsibilities of the Centre. The centre has established national networks for MS care and research and has provided supervision and education of doctors and other health care professionals in Norway. Guidelines for diagnosis and treatment of MS have been established. The National Multiple Sclerosis Registry was established in 1998 and includes by January 2006 50-60% of all MS patients in Norway. Through a national collaboration, the registry aims for inclusion of a biobank unit for collection of cerebrospinal fluid and serum, DNA, and tissue samples.