CD8+ T cell gene expression analysis identifies differentially expressed genes between multiple sclerosis patients and healthy controls.

BACKGROUND: Genetic and clinical observations have indicated T cells are involved in MS pathology. There is little insight in how T cells are involved and whether or not these can be used as markers for MS. OBJECTIVES: Analysis of the gene expression profiles of circulating CD8+ T cells of MS patients compared to healthy controls. METHODS: RNA from purified CD8+ T cells was sequenced and analyzed for differential gene expression. Pathway analyses of genes at several p-value cutoffs were performed to identify putative pathways involved. RESULTS: We identified 36 genes with significant differential gene expression in MS patients. Four genes reached at least 2-fold differences in expression. The majority of differentially expressed genes was higher expressed in MS patients. Genes associated to MS in GWAS showed enrichment amongst the differentially expressed genes. We did not identify enrichment of specific pathways amongst the differentially expressed genes in MS patients. CONCLUSIONS: CD8+ T cells of MS patients show differential gene expression, with predominantly higher activity of genes in MS patients. We do not identify specific biological pathways in our study. More detailed analysis of CD8+ T cells and subtypes of these may increase understanding of how T cells are involved in MS.

Is the hygiene hypothesis relevant for the risk of multiple sclerosis?

The hygiene hypothesis, suggesting that low exposure to pathogens early in life can increase the risk for immune-mediated diseases, has been proposed as an explanation for the increase in incidence of allergy and autoimmune diseases in industrialized countries during the last decades. Several aspects of the hygiene hypothesis have been related to MS. Already in 1966, the risk of MS was suggested to be higher in individuals with high hygienic standard during childhood. Further, an episode of infectious mononucleosis is an independent risk factor for MS and can be regarded as an indicator of low exposure to pathogens early in life, as infection with Epstein-Barr virus often is asymptomatic when it occurs in young children. Conflicting results have been reported regarding number of siblings, attendance in a day care center and exposure to animals during childhood in relation to MS risk, but common childhood infections and vaccinations do not seem to influence the risk of MS. In line with the hygiene hypothesis, two large meta-analyses have recently shown that infection with Helicobacter pylori is negatively correlated with MS. Moreover, a protective influence of helminth infection on MS has been observed in several, small clinical studies, but more knowledge is needed before a potential role of helminth-derived therapy in MS is determined. Also, it has been hypothesized that infection with the parasite Toxoplasma gondii could be protective against MS.

Infections in patients with multiple sclerosis: Implications for disease-modifying therapy.

Patients with multiple sclerosis have an increased risk of infections compared to the general population. The increased risk has been described for decades and is not alone attributed to the use of disease-modifying drugs, but secondary to the disability. The introduction of more potent immunomodulatory drugs may cause an additional challenge, and depending on the mechanism of action, a treatment-induced increased risk of bacterial, viral, fungal or parasitic infections is observed. The choice of treatment in the individual patient with infections and multiple sclerosis must be guided by the drugs' specific mechanism of action, the drug-specific risk of infection and comorbidities. Increased monitoring and follow-up through treatment registries is warranted to increase our understanding and thereby improve management.

High prevalence and increasing incidence of multiple sclerosis in the Norwegian county of Buskerud.

OBJECTIVES: The objective was to investigate the incidence of multiple sclerosis (MS) as well as estimate the prevalence as of 1 January 2014 in the southeastern Norwegian county of Buskerud. MATERIALS AND METHODS: All patients with MS living in Buskerud county in Norway between 01 January 2003 and 01 January 2014 were identified. Point prevalence of MS was identified on 01 January 2014. RESULTS: We found a prevalence of 213.8 (95% CI 196.4-231.1) per 100 000. The sex ratio was 2.2:1 with a female prevalence of 293.4 (95% CI 264.7-322.2) per 100 000 and a male prevalence of 134.7 (95% CI 115.3-154.2) per 100 000. About 82% of our MS population had a confirmed relapsing-remitting MS at disease onset, while 16.8% had primary progressive MS. The mean annual incidence between 2003 and 2013 was 11.8 (95% CI 10.6-13.1) per 100 000. CONCLUSION: This study shows a high incidence of MS in Buskerud county in southeastern Norway, and the incidence may still be on the rise. We found a relatively high prevalence of MS in our population, although this does correspond with the recently published national data. Further studies investigating both changes in incidence and possible factors causing the increasing incidence are warranted.

From genetic associations to functional studies in multiple sclerosis.

Genetic screens steadily reveal more loci that show robust associations to complex human diseases, including multiple sclerosis (MS). Although some of the identified genetic variants are easily interpreted into a biological function, most of the genetic associations are frequently challenging to interpret. Underlying these difficulties is the fact that chip-based assays typically detect single nucleotide polymorphisms (SNPs) representative of a stretch of DNA containing many genomic variants in linkage disequilibrium. Furthermore, a large proportion of the SNPs with strongest association to MS are located in regions of the DNA that do not directly code for proteins. Here we discuss challenges faced by MS researchers to follow up the large-scale genetic screens that have been published over the past years in search of functional consequences of the identified MS-associated SNPs. We discuss experimental design, tools and methods that may provide the much-needed biological insights in both disease etiology and disease manifestations.

The multiple sclerosis susceptibility genes TAGAP and IL2RA are regulated by vitamin D in CD4+ T cells.

Multiple sclerosis (MS) is an inflammatory, demyelinating disorder of the central nervous system that develops in genetically susceptible individuals. The majority of the MS-associated gene variants are located in genetic regions with importance for T-cell differentiation. Vitamin D is a potent immunomodulator, and vitamin D deficiency has been suggested to be associated with increased MS disease susceptibility and activity. In CD4+ T cells, we have analyzed in vitro vitamin D responsiveness of genes that contain an MS-associated single-nucleotide polymorphism (SNP) and with one or more vitamin D response elements in their regulatory regions. We identify IL2RA and TAGAP as novel vitamin D target genes. The vitamin D response is observed in samples from both MS patients and controls, and is not dependent on the genotype of MS-associated SNPs in the respective genes.

Migraine and frequent tension-type headache are not associated with multiple sclerosis in a Norwegian case-control study.

BACKGROUND: Inconsistent results have been obtained with regard to headache comorbidity in multiple sclerosis (MS). OBJECTIVE: Investigate the one-year prevalence of migraine and tension-type headache (TTH) in Norwegian MS patients and relate this to clinical parameters. METHODS: A questionnaire concerning headache was administered to 756 MS patients and 1090 controls and used to determine the one-year prevalence of migraine and frequent TTH. RESULTS: No significant differences were seen between patients and controls or between patients with different disease course. Less migraine was observed in patients with Expanded Disability Status Scale score (EDSS) ≥4.0. CONCLUSIONS: This case-control study does not support an association between migraine or TTH and MS.

Socio-economic factors and immigrant population studies of multiple sclerosis.

The uneven geographical distribution of multiple sclerosis (MS) and the differences in disease severity observed between different ethnic groups indicate a complex interplay between genetic and environmental risk factors involved in the disease pathogenesis. Changes in MS risk after migration suggest influence of environmental factors on disease susceptibility. Whether the risk of MS is affected by socio-economic status (SES) is still controversial. In the present review, the combined knowledge from studies of migration and SES in MS is discussed.

No association between multiple sclerosis and periodontitis after adjusting for smoking habits.

BACKGROUND AND PURPOSE: Periodontitis has been reported to be associated with several systemic disorders, and recently a possible relationship with multiple sclerosis (MS) was suggested. The aim of the present study was to investigate the association between periodontitis and MS in a Norwegian cohort. METHODS: A case-control study in 756 MS patients and 1090 controls was conducted, and logistic regression analysis, adjusting for age, gender, place of residence, mononucleosis and smoking, was performed to investigate the association between MS and periodontitis. RESULTS: In the unadjusted analysis a higher prevalence of periodontitis was seen in MS patients, but this difference was not statistically significant after adjusting for the covariates. CONCLUSIONS: The previously suggested association between MS and periodontitis is not supported in this study. Our results underline the importance of adjusting for relevant covariates in epidemiological research.

Multiple sclerosis and seizures: incidence and prevalence over 40 years.

OBJECTIVES: The prevalence of multiple sclerosis (MS) is increasing worldwide. Epileptic seizures are more common in MS patients than in the general population. The aim of this study was to investigate changes in the prevalence and incidence of MS in a well-defined population over several decades and estimate the occurrence of epilepsy in the same cohort. MATERIALS AND METHODS: Patients diagnosed with MS in the County of Vestfold, Norway in the period of 1983-2003 were identified. Point prevalence for MS and epilepsy was calculated for January 1, 2003. The average annual incidence rates were calculated in five-year periods from 1983 to 2002. These numbers were compared to previously published figures of prevalence from 1963 and incidence from 1953. RESULTS: On prevalence day, we identified 364 patients diagnosed with MS living in Vestfold. Thus, the prevalence increased from 61.6/100,000 in 1963 to 166.8/100,000 in 2003. In the period 1983-2002, the annual incidence fluctuated between 4.2 and 7.3/100,000/year (mean 4.5, 95% CI 3.6 - 5.5). In 2003, the portion of MS patients with epileptic seizures was 7.4%, compared to 2.9% in 1963. CONCLUSIONS: During the 40 years follow-up of this population, the incidence of MS was stable, while the prevalence of MS and the share of MS patients with epileptic seizures increased. Compared to the general population, the risk of having active epilepsy was increased fourfold. We assume that this is a consequence of an increased survival in MS patients.

High prevalence and no latitude gradient of multiple sclerosis in Norway.

The prevalence of multiple sclerosis (MS) is increasing, and the presence of a latitude gradient for MS risk is still discussed. We present the first nationwide prevalence estimates for Norway, spanning the latitudes from 58-71 degrees North, in order to identify a possible latitude gradient. Information from the Oslo MS Registry and the Norwegian MS Registry and Biobank was combined with data from the Norwegian Patient Registry, the Norwegian Prescription Database and Statistics Norway. We estimated a crude prevalence of 203/100,000 on 1 January 2012. The prevalence in the Northern and Southern regions were not significantly different. MS prevalence in Norway is among the highest reported worldwide. We found no evidence of a latitude gradient.

Increased disease severity in non-Western immigrants with multiple sclerosis in Oslo, Norway.

BACKGROUND AND PURPOSE: Non-Western immigrants to Norway acquire an increased risk of multiple sclerosis (MS) after migration. Ethnicity and the presence of oligoclonal bands (OCBs) in the cerebrospinal fluid (CSF) might influence the disease course. The aim of this study was to investigate differences in disease severity and in the presence of OCBs in ethnic Norwegian and immigrant MS patients. METHODS: Clinical data and CSF findings from 47 non-Western immigrants with MS were compared with those from 447 Norwegian and 48 immigrant patients from Western countries. RESULTS: The non-Western immigrants had a higher mean Multiple Sclerosis Severity Score (MSSS) than the Norwegian patients (5.68 vs. 4.13, P = 0.001). Age at onset was 4 years lower amongst the non-Western immigrants (P = 0.001). After adjusting for year of birth, age at onset, gender and disease course, the mean difference in MSSS between the groups was 2.17 (P < 0.001). Amongst the non-Western immigrants, 70% received disease-modifying drugs, compared with 48% of the Norwegian patients (P = 0.005). In both groups, 88% were OCB-positive. CONCLUSIONS: Non-Western immigrants with MS had an increased disease severity compared with native Norwegians and immigrants from Western countries. The presence of OCBs in the CSF was not different between the groups.

Low bone mass in newly diagnosed multiple sclerosis and clinically isolated syndrome.

OBJECTIVE: Osteoporosis is common in patients with multiple sclerosis (MS) with long-standing disease. Hypovitaminosis D is a candidate risk factor for MS, and vitamin D also mediates bone mineralization. If vitamin D exerts a major effect on MS risk, skeletal consequences of hypovitaminosis D could be apparent shortly after the onset of MS. In order to test this hypothesis, we assessed bone mineral density (BMD) at early stages of disease in patients with no or minor disability. METHODS: A population-based case-control study was conducted on 99 consecutive and newly diagnosed patients with clinically isolated syndrome or MS, and on 159 age-, sex-, and ethnicity-matched controls. BMD was measured by dual-energy x-ray absorptiometry of the femoral neck, total hip, anterior-posterior lumbar spine, total body, and nondominant ultradistal radius. RESULTS: A total of 50.5% of the patients exhibited either osteopenia (-2.5 < T score < -1.0) or osteoporosis (T score ≤-2.5) in at least one skeletal site, compared to 37.1% of controls (p = 0.034). After adjusting for possible confounders, left femoral total hip T score and lumbar spine BMD and T score were significantly lower in patients than in controls (p = 0.023, 0.039, and 0.026, respectively). CONCLUSIONS: Low bone mass appears to occur early in MS. This is compatible with shared etiologic or pathogenic factors in MS and osteoporosis, and calls for an active approach to optimize bone health in early stages of MS.

Fractures and falls in patients with newly diagnosed clinically isolated syndrome and multiple sclerosis.

BACKGROUND: Increased risk of falls and reduced bone strength may both contribute to enhanced fracture risk in patients with multiple sclerosis (MS). Fall tendency and fractures have not been investigated in newly diagnosed patients. OBJECTIVES: The aim was to compare the fall tendency and fracture risk in a cohort of newly diagnosed clinically isolated syndrome (CIS) and MS patients with that in the general population. METHODS: We performed a population-based case-control study in Oslo of self-reported fall tendency and fracture history in consecutive patients diagnosed with either a CIS suggestive of demyelinating disease or MS between January 2005 and January 2008. Two age-, sex-, and ethnicity-matched control groups were included; one group from the population registry and one group recruited by the patients. RESULTS: Ninety-nine patients (mean time since the first symptom 1.6 ± 1.3 years, mean expanded disability status scale [EDSS] score 1.4 ± 1.1) and 159 controls were included. Whereas no difference in the number of fractures was reported, 20% of the patients and 3% of the controls reported a tendency to fall (P<0.001). Fall tendency was associated with degree of disability (mean EDSS score among patients with and without self-reported fall tendency was 2.4 ± 1.4 and 1.1 ± 0.9, respectively; P=0.001). Fall tendency was also reported in two of 22 patients with EDSS 0. CONCLUSIONS: Fall tendency may occur early in the disease course of MS, before impairment of locomotion and balance becomes evident on clinical examination.

Exploring the CLEC16A gene reveals a MS-associated variant with correlation to the relative expression of CLEC16A isoforms in thymus.

Genomewide association studies have implicated the CLEC16A gene in several autoimmune diseases, including multiple sclerosis (MS) and type 1 diabetes. However, the most associated single-nucleotide polymorphism (SNP) varies, and causal variants are still to be defined. In MS, two SNPs in partial linkage disequilibrium with each other, rs6498169 and rs12708716, have been validated at genomewide significance level. To explore the CLEC16A association in MS in more detail, we genotyped 57 SNPs in 807 Norwegian MS patients and 1027 Norwegian controls. Six highly associated SNPs emerged and were then replicated in two large independent sample sets (Norwegian and British), together including 1153 MS trios, 2308 MS patients and 4044 healthy controls. In combined analyses, SNP rs12708716 gave the strongest association signal in MS (P=5.3 x 10⁻8, odds ratio 1.18, 95% confidence interval=1.11-1.25), and was found to be superior to the other SNP associations in conditional logistic regression analyses. Expression analysis revealed that rs12708716 genotype was significantly associated with the relative expression levels of two different CLEC16A transcripts in thymus (P=0.004), but not in blood, possibly implying a thymus- or cell-specific splice regulation.

Cognitive impairment after three decades of multiple sclerosis.

BACKGROUND: Population-based studies of cognitive impairment in patients with multiple sclerosis (MS) with long disease duration are limited. The aim of this study was to evaluate long-term outcome and the predictors of cognitive impairment in a cohort of patients with MS. METHODS: Patients living in Oslo, Norway, with definite MS and onset in 1940-1980 alive on 1 May 2006 were included. Disability was assessed by Expanded Disability Status Scale (EDSS). Cognitive functioning was assessed in terms of psychomotor speed, attention, learning/memory and executive functions. RESULTS: A total of 123 patients was included. EDSS was < or =3.0 in 26% and > or =6.0 in 60% after mean disease duration of 34.5 years. Cognitive impairment was found in 48% of the patients eligible for neuropsychological evaluation (n = 84). Typical pattern was moderate impairment within areas of information processing, attention and memory. In the univariate analysis, younger onset age was significantly associated with cognitive impairment (P = 0.014). Younger onset age (P = 0.017) and disease course (secondary progressive vs. relapsing-remitting MS, P = 0.049) were significantly associated with cognitive impairment in the multivariate analysis. CONCLUSIONS: After three decades of disease, half of the MS patients experienced reduced cognitive functioning; however, nearly one-third of the patients were only mildly disabled based on the EDSS. Younger onset age was associated with higher prevalence of cognitive impairment. A thorough evaluation of cognitive function in addition to EDSS is essential for evaluating long-term impairment in patients with MS.

Genetic variants of CC chemokine genes in experimental autoimmune encephalomyelitis, multiple sclerosis and rheumatoid arthritis.

Multiple sclerosis (MS) is a complex disorder of the central nervous system, causing inflammation, demyelination and axonal damage. A limited number of genetic risk factors for MS have been identified, but the etiology of the disease remains largely unknown. For the identification of genes regulating neuroinflammation we used a rat model of MS, myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), and carried out a linkage analysis in an advanced intercross line (AIL). We thereby redefine the Eae18b locus to a 0.88 Mb region, including a cluster of chemokine genes. Further, we show differential expression of Ccl2, Ccl11 and Ccl11 during EAE in rat strains with opposite susceptibility to EAE, regulated by genotype in Eae18b. The human homologous genes were tested for association to MS in 3841 cases and 4046 controls from four Nordic countries. A haplotype in CCL2 and rs3136682 in CCL1 show a protective association to MS, whereas a haplotype in CCL13 is disease predisposing. In the HLA-DRB1* 15 positive subgroup, we also identified an association to a risk haplotype in CCL2, suggesting an influence from the human leukocyte antigen (HLA) locus. We further identified association to rheumatoid arthritis in CCL2, CCL8 and CCL13, indicating common regulatory mechanisms for complex diseases.