Histocompatibility antigens in familial multiple sclerosis in a high-risk area of the disease

Increased Female MS Incidence and Differences in Gender-Specific Risk in Medium- and High-Risk Regions in Finland from 1981-2010

Background. MS incidence has increased among females, suggesting the presence of environmental effect. Object. Regional differences and temporal changes in gender-specific MS incidence were studied in Finland. Methods. Cases from Jan 1, 1981 to Dec 31, 2010 in Pirkanmaa, Seinäjoki and Vaasa districts were included. The standardized incidence rates (SIR), incidences per 10⁵ person years with 95% confidence intervals (CI), and female-to-male ratios (F/M) were determined by district. Results. 1617 cases were included. Compared to Pirkanmaa, the MS risk was 1.9-fold (95% CI: 1.7–2.0) greater in Seinäjoki and 1.2-fold (95% CI: 1.1–1.4) in Vaasa, and the risk was high for both genders. The incidence trend stabilized in Seinäjoki and Vaasa, accompanied by an increase in the F/M ratio. A steady increase in Pirkanmaa was accompanied by a high F/M ratio. Conclusion. A high female preponderance accompanied a general increase in incidence since the 1990s, suggesting the influence of environmental factors. In high-risk districts, increased MS risk prevailed in both genders. High risk reflects both genetic and environmental effects. These effects may be shared with autoimmune diseases such as type 1 diabetes mellitus; the incidence of which follows MS in Finland. Population-based case-control studies are needed to identify these factor effects.

The HLA-DR2 haplotype is associated with an increased proliferative response to the immunodominant CD4(+) T-cell epitope in human interferon-beta

Human CD4(+) T-cell epitopes were identified in interferon-beta (IFN-beta)-1b. A prominent peptide epitope region was found that induced a proliferative response in 16% of all donors tested. Responses corresponded to the presence of the HLA-DR2 haplotype. Responsive donors expressing the HLA-DQ6 allele showed an increased level of proliferation to the epitope as compared to peptide-responsive HLA-DQ6 negative donors. A similar result was found for HLA-DR15-expressing donors. PBMC from donors expressing HLA-DR15 were more likely to proliferate in response to IFN-beta in a whole-protein in vitro assay than donors who did not carry this haplotype. It is striking that the common DQ6 allele HLA-DQB1(*)0602 is found in linkage disequilibrium with HLA-DRB1(*)1501, and this combination defines the HLA genotype associated with the development of multiple sclerosis. The HLA association between a response to IFN-beta and MS might explain the prevalence of neutralizing antibody development, and may underlie the etiology of the disease.

Multiple sclerosis in Finland: incidence trends and differences in relapsing remitting and primary progressive disease courses

OBJECTIVE

To compare the secular trends and geographical differences in the incidence of relapsing-remitting (RRMS) and primary progressive multiple sclerosis (PPMS) in Finland, and to draw inferences about aetiological differences between the two forms of the disease.

METHODS

New multiple sclerosis cases in southern Uusimaa and the western districts Vaasa and Seinäjoki of Finland in 1979-1993 were verified from hospital records and classified into RRMS and PPMS. Patients met the Poser criteria for definite multiple sclerosis or otherwise satisfied the criteria for PPMS. Disease course was categorised by the same neurologist. Crude and age adjusted incidence in 1979-1993 was estimated.

RESULTS

During 1979-1993 the age adjusted incidence was 5.1 per 100 000 person-years in Uusimaa, 5.2 in Vaasa, and 11.6 in Seinäjoki. The rates in Uusimaa remained stable, while a decrease occurred in Vaasa and an increase in Seinäjoki. Between 1979-86 and 1987-93 the incidence of PPMS increased in Seinäjoki from 2.6 to 3.7 per 10(5) and decreased in Vaasa from 1.9 to 0.2 per 10(5); the trends were similar for RRMS.

CONCLUSIONS

There are significant differences in secular trends for multiple sclerosis incidence in Finland by geographical area, but these are similar for PPMS and RRMS. The recent changes point to locally acting environmental factors. The parallel incidence trends for RRMS and PPMS suggest similar environmental triggers for the two clinical presentations of multiple sclerosis.

The genetics of multiple sclerosis. A review

Multiple sclerosis (MS) is characterized by chronic inflammation and demyelination in the central nervous system (CNS). Although the etiology of MS is unknown, both genetic and environmental contributions to the pathogenesis are inferred from epidemiologic studies. Geographic distributions and epidemics of MS and data from migration studies provide evidence for some, thus far unidentified, environmental effects. The co-occurrence of MS with high and low frequencies in ethnic groups often sharing an environment, the increased recurrence rate in families, and the high concordance rate among identical twins point to inheritable determinants of susceptibility. Based on the autoimmune hypothesis of demyelination, genetic studies sought associations between MS and polymorphic alleles of candidate genes which regulate either the immune response or myelin production. The most consistent finding in case-control studies was the association with the major histocompatibility complex (MHC) (also called human leukocyte antigen--HLA) class II, DR15, DQ6, Dw2 haplotype. Studies on other gene products encoded within or close to the MHC complex on chromosome 6p21.3 (e.g., HLA DP, complement components, transporter proteins, tumor necrosis factor, and myelin-oligodendrocyte glycoprotein) resulted in conflicting observations in different patient populations. The potential contribution of polymorphic alleles within the genes of the T-cell receptor alpha beta chains, immunoglobulins, cytokines, and oligodendrocyte growth factors or their receptors to MS susceptibility either remains equivocal or is rejected. Studies on families with multiple affected members have revealed that MS is a complex trait, that the contribution of individual genes to susceptibility is probably small, and that differences are possible between familial and sporadic forms. The development of molecular and computer technologies have facilitated the performance of comprehensive genomic scans in multiplex families, which have confirmed the possible linkage of multiple loci to susceptibility, each with a minor contribution. Several provisional sites were reported, but only 6p21 (MHC complex), 5p14, and 17q22 were positive in more than one study. The British update demonstrated segregation among regions of interest depending on DR15 sharing, and excluded a gene of major effect from 95%, and one with a moderate effect from 65% of the genome. The extended study by the US collaboration group revealed that the MHC linkage was limited to families segregating HLA DR2 alleles, which suggested that linkage to the MHC is related to the HLA DR2 association, and that sporadic and familial MS share at least one common susceptibility marker. Further identification of MS susceptibility loci may involve additional family sets, more polymorphic markers, and the exploration of telomeric chromosomal regions. Data from these studies may further elucidate pathogenic mechanisms of MS.

Multiple sclerosis: multiple etiologies, multiple genes?

Multiple sclerosis is a chronic inflammatory disease characterized by multifocal damage of the central nervous system myelin. Both humoral and cell-mediated immune abnormalities have been observed in patients with multiple sclerosis, but their relation to the demyelination process is not understood. The etiology of the disease is still unknown; however, evidence exists for an interplay between environmental and genetic factors. Several genes are involved in determining the disease susceptibility, at least one of them encoded within human leukocyte antigen gene complex. Other genomic regions coding for components of the immune system or myelin have also been suggested. Clinical, immunological and genetic data suggest that multiple sclerosis may turn out to be a heterogeneous disease. Therefore, molecular genetic dissection of this complex disease should provide important clues to its pathogenesis as well as unravel metabolic pathways for potential therapeutic or preventive strategies. This review will give an overview of recent progress and future challenges in identifying susceptibility genes for multiple sclerosis.

Immunological studies on patients with optic neuritis without evidence of multiple sclerosis

We studied 6 patients with idiopathic optic neuritis (ON) after a mean follow-up period of 12 years. No evidence of multiple sclerosis (MS) was found on clinical grounds, nor by magnetic resonance imaging (MRI) or evoked responses. Levels of spontaneous proliferation, serum gamma-interferon (IFN-gamma) and lymphocyte MHC locus II antigen were similar in ON and in 6 patients with progressive MS, but different in healthy controls. This suggests that similar immunological conditions in vivo prevail after an idiopathic ON and in MS. A normal PHA-induced interleukin-2 receptor expression and lymphocyte proliferation but a low IFN-gamma secretion and MHC locus II antigen expression were observed. This suggests that an ON and MS defect is expressed after an interleukin-2 receptor ligand but before IFN-gamma secretion. Our findings also suggest that immunological factors do not explain the neuropathological confinement of the lesions in ON but the protective influence may rather be exerted by some as yet undefined genetic influence or may be explained by the different etiology of ON and MS.

Myasthenia gravis associated with multiple sclerosis. Epidemiological survey and immunological findings

Patient registers on myasthenia gravis (94 patients) and multiple sclerosis (991 patients) from a population of 1.5 million were reviewed to find patients with both diseases. Seven potential candidates were found, but both diagnoses were confirmed in 2 women only. The first patient had also iritis, the second patient had, besides MG and MS, bronchial asthma and polyarthritis. Both neurological diseases had a relatively mild clinical course. Thymectomy relieved MG symptoms in both patients. Cerebrospinal fluid studies during the follow-up indicated immunoactivation within the central nervous system. Changes in cellular immunity were also noted. The HLA types were different. The combination of these two diseases appears to be more common than expected.

Optic neuritis in children and its relationship to multiple sclerosis: a clinical study of 21 children

The optic neuritis of 21 children aged between four and 14 years generally was characterized by bilateral involvement (62 per cent) and papillitis (76 per cent). Often acute infections or vaccinations were preceding events. Frequently there was pleocytosis during the disease process, with production of IgG, oligoclonal and viral antibodies, which increased during follow-up. Nine of these children (eight female) later developed multiple sclerosis, with unilateral involvement of the optic nerves and HLA Dr2 positivity. Disseminated effects on the central nervous system were similar to those of adults with multiple sclerosis. In all cases these relapses occurred within one year of the optic neuritis. EEGs did not differentiate those who developed multiple sclerosis from those who did not, but four of five patients with multiple sclerosis who were followed-up for a year or more had paroxysmal discharges, and one of the four had manifest epilepsy. Magnetic resonance imaging, visual and sensory evoked potentials and CSF studies were helpful in diagnosing multiple sclerosis. The visual prognosis was good in most cases. 17 children had no or only slight neurological disability at the end of follow-up; the other four had moderate to severe disability. This study suggests that optic neuritis is a diffuse disease, not merely affecting the optic nerves, and that the immunological events typical of multiple sclerosis can start in childhood.

Familial multiple sclerosis

Siblings of patients with multiple sclerosis have an increased risk of developing the disease. In this report we describe 3 families with multiple affected members, representing the largest published aggregation of cases in first degree relatives. In the 2 families in which HLA tissue-typing was performed the affected individuals shared part of the haplotype HLA-DR2 (+ HLA-DQW1), BfS (+ C2C), C4A3, C4B1. The implications of these findings for the aetiology of multiple sclerosis are discussed.

Evaluation of central nervous system involvement in uncomplicated optic neuritis after prolonged follow-up

Magnetic resonance imaging (MRI), multimodal evoked responses (ER) and HLA antigens were examined in 10 patients with idiopathic acute optic neuritis (ON) without any clinical symptoms or signs of multiple sclerosis (MS) during 9-14 years. In MRI, abnormalities compatible with MS were seen in 4 patients. In spite of clinically unilateral ON, a bilateral abnormality in visual evoked responses (VER) was seen in 3 of 9 cases. Brain stem auditory evoked responses (BAER) were normal in all cases, short latency somatosensory evoked response (SER) in all but one. The cerebrospinal fluid at time of ON showed signs of demyelination in one case only. The frequency of HLA antigens DR2 (78%) and B18 (40%) was significantly increased in comparison to healthy controls. MRI seems to be the most sensitive method in the detection of cerebral lesions of MS, especially in mild or asymptomatic forms of the disease. The present techniques are, however, mostly unable to demonstrate optic nerve lesions which more reliably can be evaluated by VERs. The question whether idiopathic ON represents a form of MS solely, cannot be resolved.