Multiple sclerosis in Australia and New Zealand: are the determinants genetic or environmental?

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Epidemiological study of multiple sclerosis in Illawarra region

BACKGROUND

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease which causes significant disabilities. Latest MS epidemiological data in Australia reveals rising prevalence. No epidemiological study of MS has been conducted so far in the Illawarra region.

AIM

To calculate prevalence and incidence of MS in the Illawarra and compare with other regions', states' and national prevalence data.

METHOD

Data of MS patients in the Illawarra were collected from hospital medical records, ambulatory care units and hospital pharmacy. Prevalence was calculated for alive MS patients on June 30, 2018 expressed per 100 000 population. Yearly adjusted incidence rate was calculated for 10 years (2009-2019), expressed as cases per 100 000 population-years.

RESULTS

Estimated MS prevalence in the Illawarra was 116.6 per 100 000 population with yearly incidence (2009-2019) of 5.06 cases per 100 000 population-years (female to male, 3:1). Relapsing-remitting MS (RRMS) was the most common type (277/397 ~ 69.7%) with primary progressive MS (PPMS) in 52/397 ~ 13%, and secondary progressive MS (SPMS) in 45/397 ~ 11.3% (unknown in 23). Commonest age at diagnosis ranged between 30-39 years for all types with RRMS and PPMS between 30-39 years and 40-49 years respectively. The most commonly recorded treatment was natalizumab (103 patients) followed by fingolimod (82 patients) and interferon (58 patients).

CONCLUSION

The calculated MS prevalence in the Illawarra is higher than NSW and Australian average MS prevalence. Further epidemiological studies focusing on MS risk factors and other factors bearing on MS prevalence in the Illawarra are required. This article is protected by copyright. All rights reserved.

NMOSD and MS prevalence in the Indigenous populations of Australia and New Zealand

BACKGROUND

We studied the prevalence of neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) in Indigenous populations of Australia and New Zealand with the aim of assessing potential differences.

METHODS

Cases of possible NMOSD and MS were collected from Australia and New Zealand. Clinical details, MR imaging, and serologic results were used to apply 2015 IPND diagnostic criteria for NMOSD and 2010 McDonald criteria for MS. Frequencies of self-determined ethnic ancestry were calculated for confirmed NMOSD, suspected NMOSD, and MS. Prevalence rates for NMOSD and MS according to ancestry were compared.

RESULTS

There were 75 cases with NMOSD, 89 with suspected NMSOD, and 101 with MS. NMOSD cases were more likely to have Asian, Indigenous, or Other ancestry compared to suspected NMOSD or MS. There were no differences in the clinical phenotype of NMOSD seen in Indigenous compared to European ancestry populations. Per 100,000, the prevalence estimate for NMOSD in people with Māori ancestry was 1.50 (95% CI 0.52-2.49) which was similar to those with Asian ancestry 1.57 (95% CI 1.15-1.98). NMOSD prevalence in Australian Aboriginal and Torres Strait Islander populations was 0.38 (95% CI 0.00-0.80) per 100,000.

CONCLUSION

The prevalence of NMOSD in the Māori population is similar to South East Asian countries, reflecting their historical origins. The prevalence of MS in this group is intermediate between those with South East Asian and European ancestry living in New Zealand. Both NMOSD and particularly MS appear to be uncommon in the Indigenous populations of Australia.

Expression of CYP24A1 and other multiple sclerosis risk genes in peripheral blood indicates response to vitamin D in homeostatic and inflammatory conditions

Although genetic and epidemiological evidence indicates vitamin D insufficiency contributes to multiple sclerosis (MS), and serum levels of vitamin D increase on treatment with cholecalciferol, recent metanalyses indicate that this vitamin D form does not ameliorate disease. Genetic variation in genes regulating vitamin D, and regulated by vitamin D, affect MS risk. We evaluated if the expression of vitamin D responsive MS risk genes could be used to assess vitamin D response in immune cells. Peripheral blood mononuclear cells (PBMCs) were isolated from healthy controls and people with MS treated with dimethyl fumarate. We assayed changes in expression of vitamin D responsive MS risk (VDRMS) genes in response to treatment with 25 hydroxy vitamin D in the presence or absence of inflammatory stimuli. Expression of CYP24A1 and other VDRMS genes was significantly altered in PBMCs treated with vitamin D in the homeostatic and inflammatory models. Gene expression in MS samples had similar responses to controls, but lower initial expression of the risk genes. Vitamin D treatment abrogated these differences. Expression of CYP24A1 and other MS risk genes in blood immune cells indicate vitamin D response and could enable assessment of immunological response to vitamin D in clinical trials and on therapy.

Regulation of the methylome in differentiation from adult stem cells may underpin vitamin D risk in MS

Multiple lines of evidence indicate Multiple Sclerosis (MS) is affected by vitamin D. This effect may be mediated by methylation in immune cell progenitors. We aimed to determine (1) if haematopoietic stem cell methylation constrains methylation in daughter cells and is variable between individuals, and (2) the interaction of methylation with the vitamin D receptor binding sites. We interrogated genomic methylation levels from matching purified CD34+ haematopoietic stem cells and progeny CD14+ monocytes and CD56+ NK cells from 11 individuals using modified reduced representation bisulfite sequencing. Differential methylation of Vitamin D Receptor binding sites and MS risk genes was assessed from this and using pyrosequencing for the vitamin D regulated MS risk gene ZMIZ1. Although DNA methylation states at CpG islands and other sites are almost entirely recapitulated between progenitor and progeny immune cells, significant variation was detected at some regions between cell subsets and individuals; including around the MS risk genes HLA DRB1 and the vitamin D repressor NCOR2. Methylation of the vitamin D responsive MS risk gene ZMIZ1 was associated with risk SNP and disease. We conclude that DNA methylation settings in adult haematopoietic stem cells may contribute to individual variation in vitamin D responses in immune cells.

Lifetime exposure to ultraviolet radiation and the risk of multiple sclerosis in the US radiologic technologists cohort study

BACKGROUND

Low exposure to ultraviolet radiation (UVR) from sunlight may be a risk factor for developing multiple sclerosis (MS). Possible pathways may be related to effects on immune system function or vitamin D insufficiency, as UVR plays a role in the production of the active form of vitamin D in the body.

OBJECTIVE

This study examined whether lower levels of residential UVR exposure from sunlight were associated with increased MS risk in a cohort of radiologic technologists.

METHODS

Participants in the third and fourth surveys of the US Radiologic Technologists (USRT) Cohort Study eligible (N = 39,801) for analysis provided complete residential histories and reported MS diagnoses. MS-specialized neurologists conducted medical record reviews and confirmed 148 cases. Residential locations throughout life were matched to satellite data from NASA's Total Ozone Mapping Spectrometer (TOMS) project to estimate UVR dose.

RESULTS

Findings indicate that MS risk increased as average lifetime levels of UVR exposures in winter decreased. The effects were consistent across age groups <40 years. There was little indication that low exposures during summer or at older ages were related to MS risk.

CONCLUSION

Our findings are consistent with the hypothesis that UVR exposure reduces MS risk and may ultimately suggest prevention strategies.

The role of vitamin D and P2X7R in multiple sclerosis

Multiple sclerosis (MS) is characterized by neuroinflammatory infiltrates and central nervous system demyelination. In the neuroinflammatory foci of MS there is increased expression of a purinergic receptor, P2X7R. Although implicated in the neuroinflammation, the exact role of P2X7R in the context of MS is unclear and forms the basis of this review. In this review, we also introduce the immunopathologies and inflammatory processes in MS, with a focus on P2X7R and the possible immunomodulatory role of vitamin D deficiency in this setting.

The latitude-dependent autoimmune disease risk genes ZMIZ1 and IRF8 regulate mononuclear phagocytic cell differentiation in response to vitamin D

Epidemiological, molecular and genetic studies have indicated that high serum vitamin D levels are associated with lower risk of several autoimmune diseases. The vitamin D receptor (VDR) binding sites in monocytes and dendritic cells (DCs) are more common in risk genes for diseases with latitude dependence than in risk genes for other diseases. The transcription factor genes Zinc finger MIZ domain-containing protein 1 (ZMIZ1) and interferon regulatory factor 8 (IRF8)-risk genes for many of these diseases-have VDR binding peaks co-incident with the risk single nucleotide polymorphisms (SNPs). We show these genes are responsive to vitamin D: ZMIZ1 expression increased and IRF8 expression decreased, and this response was affected by genotype in different cell subsets. The IL10/IL12 ratio in tolerogenic DCs increased with vitamin D. These data indicate that vitamin D regulation of ZMIZ1 and IRF8 in DCs and monocytes contribute to latitude-dependent autoimmune disease risk.

Sunshine, Sea, and Season of Birth: MS Incidence in Wales

Maternal sun exposure in gestation and throughout the lifetime is necessary for vitamin D synthesis, and living near the sea is a population level index of seafood consumption. The aim of this study was to estimate the incidence rate of multiple sclerosis (MS) in Wales and examine its association with sun exposure, coastal living, and latitude. The study used a database of MS hospital visits and admissions in Wales between 2002 and 2013. For the 1,909 lower layer super output areas (LSOAs) in Wales, coastal status, population, longitude/latitude, and average sunshine hours per day were obtained. Age-specific and age-standardised MS incidence were calculated and modelled using Poisson regression. The distribution of births by month was compared between MS cases and the combined England and Wales population. There were 3,557 new MS cases between 2002 and 2013, with an average annual incidence of 8.14 (95% CI: 7.69–8.59) among males and 12.97 (95% CI: 12.44–13.50) among females per 100,000 population. The female-to-male ratio was 1.86:1. For both sexes combined, the average annual incidence rate was 9.10 (95% CI: 8.80–9.40). All figures are age-standardized to the 1976 European standard population. Compared to the combined England and Wales population, more people with MS were born in April, observed-to-expected ratio: 1.21 (95% CI: 1.08–1.36). MS incidence varied directly with latitude and inversely with sunshine hours. Proximity to the coast was associated with lower MS incidence only in easterly areas. This study shows that MS incidence rate in Wales is comparable to the rate in Scotland and is associated with environmental factors that probably represent levels of vitamin D.

Cistromic and genetic evidence that the vitamin D receptor mediates susceptibility to latitude-dependent autoimmune diseases

The vitamin D receptor (VDR) is a ligand-activated transcription factor that regulates gene expression in many cell types, including immune cells. It requires binding of 1,25 dihydroxy vitamin D3 (1,25D3) for activation. Many autoimmune diseases show latitude-dependent prevalence and/or association with vitamin D deficiency, and vitamin D supplementation is commonly used in their clinical management. 1,25D3 is regulated by genes associated with the risk of autoimmune diseases and predominantly expressed in myeloid cells. We determined the VDR cistrome in monocytes and monocyte-derived inflammatory (DC1) and tolerogenic dendritic cells (DC2). VDR motifs were highly overrepresented in ChIP-Seq peaks in stimulated monocyte (40%), DC1 (21%) and DC2 (47%), P<E(-100) for all. Of the nearly 11 000 VDR-binding peaks identified across the genome in DC1s, 1317 were shared with DC2s (91% of DC2 sites) and 1579 with monocytes (83% of monocyte sites). Latitude-dependent autoimmune disease risk polymorphisms were highly overrepresented within 5 kb of the peaks. Several transcription factor recognition motifs were highly overrepresented in the peaks, including those for the autoimmune risk gene, BATF. This evidence indicates that VDR regulates hundreds of myeloid cell genes and that the molecular pathways controlled by VDR in these cells are important in maintaining tolerance.

Long-term epidemiology of multiple sclerosis in the Northern Seville District

OBJECTIVES

Comprehensive epidemiologic data for multiple sclerosis (MS) in Spain are limited. The aim of this study was to collect epidemiologic data on MS in the Northern Seville District of Spain.

MATERIALS AND METHODS

This longitudinal study identified possible MS cases every year from nine centres between 1 January 1991 and 31 December 2011. Patients with a confirmed diagnosis of MS were included. MS data prior to enrolment were collected retrospectively from clinical records and prospectively during quarterly follow-up clinic visits. Variables included age at onset, age at diagnosis, treatment, follow-up duration, number of visits, number of relapses, change in the number of relapses over time and Expanded Disability Status Scale score. The incidence and prevalence of MS rate were calculated.

RESULTS

Overall, 156 patients with MS were identified (111 females; mean follow-up 7.5 years). Most patients had relapsing-remitting MS (73.7%); primary progressive disease was less frequent than secondary disease (10.9% vs 15.4%). The yearly incidence of MS was 4.6 per 100,000, and the prevalence at 31 December 2011 was 90.2 per 100,000.

CONCLUSIONS

The annual MS incidence rate in this southern region of Spain was higher than previously reported rates in Spanish studies.

Comparison of serum vitamin D level in multiple sclerosis patients, their siblings, and healthy controls

BACKGROUND

Multiple sclerosis (MS) is an autoimmune, neuro-inflammatory disease of central nervous system affecting physical, emotional, and cognitive aspects of patients. Association of vitamin D deficiency and MS has been shown in previous studies. The aim of this study was to evaluate serum vitamin D level in MS cases and their sex-matched healthy siblings (who are genetically near similar) and non-relative sex-matched healthy controls.

METHODS

A total of 135 subjects enrolled in this case-control study. Group one (n = 45) consisted of patients with established MS. Group two (n = 45) included sex-matched healthy siblings of the group one and group three participants (n = 45) were non-relative sex-matched healthy controls. Demographic data (age, sex), level of education, daily sun exposure duration, and month of birth gathered for all. Serum sample of all participants was collected for 25-hydroxy vitamin D measurement.

RESULTS

There was no significant difference between vitamin D level, sun exposure duration, education level, and season of birth in three evaluated groups. Mean vitamin D level was 8.2 ± 10.1 (nmol/l) in women and 13.3 ± 7 (nmol/l) in men (P = 0.001). There was a significant positive correlation between daily sun exposure duration and vitamin D level in whole participants (r = 0.28, P < 0.001) as well as in MS patients (r = 0.32, P = 0.030). Mean vitamin D level was significantly lower in participants who have born in spring and summer.

CONCLUSION

Vitamin D deficiency is high among Iranian population as well as MS patients.

Treatment update in multiple sclerosis

Multiple sclerosis is the most common cause of disability in young people in the Western world. Reduced life expectancy and worsening quality of life due to increasing disability later in the disease course have significant personal and societal costs. Changes in treatment strategies and newly available treatments hope to improve the outlook for our often young patients. This paper details currently available treatments and some that are expected to reach the market shortly.

Pharmacoepidemiology and the Australian regional prevalence of multiple sclerosis

Background:

Over some 50 years, field surveys have shown that the prevalence of multiple sclerosis (MS) increases with increasing distance from the equator in both the northern and the southern hemispheres. Such a latitudinal gradient has been found in field surveys of MS prevalence carried out at different times in various local regions of Australia.

Objective:

The objective of this paper is to use a pharmacoepidemiological approach to obtain whole of population estimates of the prevalence of MS in the various Australian states and territories from the use of MS disease-modifying drugs used to treat relapsing–remitting MS (RRMS).

Methods:

We analysed the dispensed use of subsidised RRMS drugs by jurisdiction.

Results:

In the 2005–2008 period, the calculated mean treated RRMS prevalence in Australia ranged from 7.5 per 100,000 in the far north to 53.2 per 100,000 in the extreme south and was linearly related to increasing southerly latitude. Public domain Australian data suggested that multiplying this prevalence by a factor of 2.2 (to account for untreated RRMS and other types of MS) may provide a measure of the prevalence of all varieties of the disease.

Conclusion:

These findings provide contemporary and more comprehensive evidence for the gradient of MS prevalence with latitude in Australia than has previously been available.

IL7Rα contributes to experimental autoimmune encephalomyelitis through altered T cell responses and nonhematopoietic cell lineages

A mutation in the IL7Rα locus has been identified as a risk factor for multiple sclerosis (MS), a neurodegenerative autoimmune disease characterized by inflammation, demyelination, and axonal damage. IL7Rα has well documented roles in lymphocyte development and homeostasis, but its involvement in disease is largely understudied. In this study, we use the experimental autoimmune encephalomyelitis (EAE) model of MS to show that a less severe form of the disease results when IL7Rα expression is largely restricted to thymic tissue in IL7RTg(IL7R-/-) mice. Compared with wild-type (WT) mice, IL7RTg(IL7R-/-) mice exhibited reduced paralysis and myelin damage that correlated with dampened effector responses, namely decreased TNF production. Furthermore, treatment of diseased WT mice with neutralizing anti-IL7Rα Ab also resulted in significant improvement of EAE. In addition, chimeric mice were generated by bone marrow transplant to limit expression of IL7Rα to cells of either hematopoietic or nonhematopoietic origin. Mice lacking IL7Rα only on hematopoietic cells develop severe EAE, suggesting that IL7Rα expression in the nonhematopoietic compartment contributes to disease. Moreover, novel IL7Rα expression was identified on astrocytes and oligodendrocytes endogenous to the CNS. Chimeric mice that lack IL7Rα only on nonhematopoietic cells also develop severe EAE, which further supports the role of IL7Rα in T cell effector function. Conversely, mice that lack IL7Rα throughout both compartments are dramatically protected from disease. Taken together, these data indicate that multiple cell types use IL7Rα signaling in the development of EAE, and inhibition of this pathway should be considered as a new therapeutic avenue for MS.

The role of Acinetobacter in the pathogenesis of multiple sclerosis examined by using Popper sequences

Multiple sclerosis (MS) is an autoimmune neurological disorder. The role of 'Acinetobacter' has been examined using the method of Karl Popper and involves nine "Popper sequences". (1) The frequency of MS increases with latitudes in the Northern Hemisphere, and the reverse is found in the Southern Hemisphere. (2) Sinusitis is found frequently at colder latitudes. (3) Sinusitis occurs frequently in patients with MS. (4) Specific sequences of bovine myelin when injected into experimental animals will produce a neurological disorder resembling MS which is called "experimental allergic encephalomyelitis". (5) Computer analysis of myelin shows molecular mimicry with sequences found in Acinetobacter. (6) Antibodies to Acinetobacter bacteria are found in MS patients. (7) Acinetobacter bacteria are located on human skin and in the nasal sinuses. (8) IgA antibodies are preferentially elevated in the sera of MS patients, thereby suggesting the trigger microbe is acting across a mucosal surface probably located in the nasal sinuses. (9) Only Acinetobacter bacteria and no other microbes evoke statistically significant titres of antibodies in MS patients. These nine Popper sequences suggest that MS is most probably caused by infections with Acinetobacter bacteria in the nasal sinuses, and this could have therapeutic implications.

Multiple sclerosis: a chronic infective cerebrospinal venulitis?

The aetiology proposed for the development of chronic cerebrospinal venous insufficiency (CCSVI) associated with multiple sclerosis (MS) has been the presence of congenital truncular venous malformations. However, this hypothesis is not consistent with the epidemiology or geographical incidence of MS and is not consistent with many of the ultrasonographic or radiographical findings of the venous disturbances found in MS patients. However, the probability of a venous aetiology of MS remains strong based on evidence accumulated from the time the disorder was first described. The method used in this review was to search PubMed for all past medical publications related to vascular, venous, haematological, epidemiological, biochemical, and genetic investigations and treatments of MS. Epidemiological and geographical findings of prevalence of MS indicate the involvement of an infective agent. This review of the venous pathology associated with MS describes a hypothesis that the pathogenesis of the venous disease could be initiated by a respiratory infective agent such as Chlamydophila pneumonia, which causes a specific chronic persistent venulitis affecting the cerebrospinal venous system. Secondary spread of the agent would initially be via the lymphatic system to specifically involve the azygos, internal jugular and vertebral veins. The hypothesis proposes mechanisms by which an infective venous vasculitis could result in the specific neural damage, metabolic, immunological and vascular effects observed in MS. The hypothesis described is consistent with many of the known facts of MS pathogenesis and therefore provides a framework for further research into a venous aetiology for the disease. If MS does result from a chronic infective venulitis rather than a syndrome involving congenital truncular venous malformations, then additional therapies to the currently used angioplasties will be required to optimize results.

The role of latitude, ultraviolet radiation exposure and vitamin D in childhood asthma and hayfever: an Australian multicenter study

Observations of increasing allergy prevalence with decreasing distance from the Equator and positive associations with ambient ultraviolet radiation have contributed to a growing interest in the possible role of vitamin D in the etiology of allergy. The aims of this study were to describe any latitudinal variation in the prevalence of childhood allergy in Australia and to evaluate, in parallel, the individual associations between ultraviolet radiation (UVR)- and vitamin D-related measures and hayfever asthma and both conditions. Participants were population-based controls who took part in a multicenter case-control study, aged 18-61 yr and resident in one of four study regions ranging in latitude from 27°S to 43°S. Data were derived from a self-administered questionnaire, interview and examination by a research officer and biologic sampling. Latitude and longitude coordinates were geocoded from participants' residential locations and climatic data were linked to postcodes of current residence. Stored serum was analyzed for 25-hydroxyvitamin D concentrations and silicone rubber casts of the skin were used as an objective measure of cumulative actinic damage. There was an inverse latitude gradient for asthma (a 9% decrease per increasing degree of latitude); however, this pattern did not persist after adjusting for average daily temperature. There was no association between any of the UVR- or vitamin D-related measures and childhood asthma, but greater time in the sun in winter between the ages 6-15 yr was associated with an increase in the odds of having hayfever [adjusted odds ratios (OR) 1.29; 95% CI 1.01-1.63]. Oral supplementation with cod liver oil in childhood increased the odds of a history of having both asthma and hayfever (2.87; 1.00-8.32). Further investigation of the possible role of early vitamin D supplementation in the development of allergy is warranted. Our results also suggest that solar exposure during childhood may be important in allergic sensitization. Plausible explanations, including biologic mechanisms, exist for both observations.

Environmental triggers of multiple sclerosis

Multiple sclerosis is a chronic immune-mediated disease of the central nervous system that develops in young adults with a complex genetic predisposition. Similar to other autoimmune disease, HLA-DR and -DQ alleles within the HLA class II region on chromosome 6p21 are by far the strongest risk-conferring genes. Less robust susceptibility effects have been reported for non-MHC related genetic variants. Improvements in the design of epidemiological studies helped to identify consistent environmental risk-associations such as the increased susceptibility for MS in individuals with a history of infectious mononucleosis, a symptomatic primary infection with the human γ-herpesvirus Epstein-Barr virus (EBV). Sun exposure and serum vitamin D levels are emerging non-infectious environmental risk factors that may have independent roles. The analysis of environmental effects will likely expand in the next few years and will allow for the generation of testable hypotheses as to how environmental insults interact with genetic factors to jointly determine the susceptibility to MS. Insights gained from these studies might facilitate the development of prevention strategies and more effective treatments for MS.

Gender issues in multiple sclerosis: an update

Although multiple sclerosis (MS) affects both women and men, women are more susceptible to MS than men. Accumulating evidence indicates that the incidence and prevalence of MS is increasing, more so in women than in men. Owing to pregnancy, differing hormonal states and distinct social roles, the impact of MS differs between women and men. Since Patricia K Coyle published a review on gender issues in MS, multiple studies have added to the body of knowledge. This update will summarize the current thinking on gender-related issues in MS and we will address incidence and prevalence, hormonal factors, pregnancy and breastfeeding, genetics, course and prognosis, imaging, treatment and psychosocial aspects. Future progression within this field will help elucidate the cause of and define the treatment of MS.

Multiple sclerosis, vitamin D, and HLA-DRB1*15

BACKGROUND

Multiple sclerosis (MS) has a remarkable geographic distribution inversely paralleling that of regional ultraviolet radiation, supporting the hypothesis that vitamin D plays a central role in the disease etiology. The major histocompatibility complex exerts the largest genetic contribution to MS susceptibility, but much risk remains unexplained and direct gene-environment interaction is a strong candidate for this additional risk. Such interactions may hold the key for disease prevention.

RECENT DEVELOPMENTS

Several recent studies strengthen the candidacy of vitamin D as a key player in the causal cascade to MS. This includes a newly identified gene-environment interaction between vitamin D and the main MS-linked HLA-DRB1*1501 allele and evidence showing that vitamin D levels are significantly lower in patients with MS as compared to controls. Also, a recent study in twins with MS supports the notion that vitamin D levels are under regulation by genetic variation in the 1alpha-hydroxylase and vitamin D receptor genes, perhaps pointing to their importance in the disease pathogenesis.

CONCLUSIONS

These findings have important practical implications for studies of disease mechanisms and prevention. Missing genetic risk may partly be explained by gene-environment interactions. More practically important is that these observations highlight a pressing need to determine if vitamin D supplementation can reduce the risk of multiple sclerosis (MS). However, the timing of action and the tissues in which this interaction takes place are not clear and future studies in prospective cohorts and animal models will be essential for deciphering the role of vitamin D in MS.

Vitamin D and multiple sclerosis

The hypothesis that adequate vitamin D nutrition can contribute to the prevention of multiple sclerosis (MS) was originally proposed to explain the geographical distribution of MS, but only recently has the relation between various measures of vitamin D (eg, sun exposure, dietary sources, and serum concentrations of 25-hydroxyvitamin D) and risk of developing MS been rigorously investigated. Overall, the results of these studies support a protective effect of vitamin D, but there are uncertainties and many unanswered questions, including how vitamin D exerts a protective effect, how genetic variations modify the effect, and whether vitamin D can influence the course of MS progression.

Epidemiology of Multiple Sclerosis

This chapter discusses the environmental factors associated to epidemiology of multiple sclerosis. The epidemiologic evidence points to three environ­mental risk factors—infection with the Epstein-Barr virus (EBV), low levels of vitamin D, and cigarette smoking—whose association with multiple sclerosis (MS) seems to satisfy in varying degrees most of the criteria that support causality, including temporality, strength, consis­tency, biologic gradient, and plausibility. None of these associations, however, has been tested experimentally in humans and only one––vitamin D deficiency is presently amenable to experimental interventions. The evidence, albeit more sparse and inconsistent, linking other environmental factors to MS risk are summarized. Epidemiologic clues to the hypothetical role of infection in MS are com­plex and often seem to point in opposite directions. The ecological studies, database/linkage analyses, and longitudinal studies of sunlight exposure and vitamin D are reviewed. Biologic mechanisms for smoking and increased risk of MS could be neuro­toxic, immunomodulatory, vascular, or they could involve increased frequency and duration of respiratory infections. Some other possible risk factors include––diet and hepatitis B vaccine.

A Comparative Study of 25 (OH) Vitamin D Serum Levels in Patients with Multiple Sclerosis and Control Group in Isfahan, Iran

OBJECTIVES

There is no study about correlation between vitamin D serum level and multiple sclerosis (MS) in Iran. So in this survey, we investigated the serum level of 25-hydroxy vitamin D in MS patients and compared it with controls in central region of Iran, an area with medium to high risk for MS disease, in spite of high sun exposure.

METHODS

A case-control study was conducted from July 1, 2008 to July 31, 2009. We enrolled 50 definitive MS patients, according to McDonald's criteria as case group and 50 matched controls. Our age limits were 15 to 55 years and those patients with estimated expanded disability status scale less than 5 were introduced to the study. We measured serum level of 25-hydroxy vitamin D and compared them between the two groups.

RESULTS

We gathered 42 females and 8 males as case group and the same numbers as control group without significant age difference. The mean serum level of 25-hydroxy vitamin D in case and control groups were 48 and 62 nmol/L, respectively, and the difference was significant (P=0.036). Also, our study showed significant discrepancy between the two groups according to the rate of deficiency, insufficiency and normal range of vitamin D categories (P=0.021).

CONCLUSIONS

We found the same results as those studies carried out in Europe and North America; i.e., lower serum vitamin D level in MS patients than that in normal population, in spite of sufficient sun exposure in Isfahan region.

Multiple sclerosis: geoepidemiology, genetics and the environment

Multiple sclerosis (MS) is a chronic immune-mediated demyelinating disease of the central nervous system characterized by relapses and remissions. The risk of acquiring this complex disease is associated with exposure to environmental factors in genetically susceptible individuals. The epidemiology of MS has been extensively studied. We review the geographic epidemiology of the disease, the influence of immigration, age at immigration, clustering and epidemics. Various presumptive risk factors are discussed such as ultraviolet radiation, vitamin D, Epstein-Barr virus and infectious mononucleosis, other infectious agents and non-infectious factors. Two different hypotheses, the hygiene hypothesis and the prevalence hypothesis, were proposed to explain these environmental risk factors for MS. The epidemiological data, combined with pathological and immunological data, may contribute to the debate whether MS is an autoimmune disease, a latent or persistent viral disease, or a neurodegenerative disease.

High prevalence of multiple sclerosis in the Swedish county of Värmland

Previous epidemiological studies have indicated that the county of Värmland in western Sweden may be a high-risk zone for multiple sclerosis (MS). The objective of this study was to determine the prevalence in the area. Hospital and general practice medical files were scrutinized. The diagnostic criteria of Poser were used, with 31 December 2002 as prevalence day. The prevalence was 170.07 per 100,000 inhabitants. The average annual incidence was 6.39 to 6.46 per 100,000 (1991—1995, 1996—2000). Multiple sclerosis was 2.3 times more common among women than men. There was a variation in prevalence among the 16 municipalities, however it was not statistically significant. The rates seemed highest in the southwestern part of the county, roughly similar in location to findings some 70 years earlier. When the prevalence ratios by geographical units for the county in 1933 were applied to the current prevalence, the distribution from these estimated cases differed from homogeneity with very high significance (p < 0.00001 ). In conclusion, this study supports previous reports indicating that Värmland continues to be a high-risk zone for MS and shares in the diffusion of the disease at the county level which we had presented for the country as a whole.

Temporal trends in the incidence of multiple sclerosis: a systematic review

BACKGROUND

Multiple sclerosis (MS) has been traditionally considered to be more frequent in women and in regions more distant from the equator. However, recent reports suggest that the latitude gradient could be disappearing and that the female-to-male ratio among patients with MS has increased in the last decades. We have conducted a systematic review of incidence studies of MS to assess the overall incidence of MS and explore possible changes in the latitude gradient and the female-to-male ratio over time.

METHODS

Systematic review of incidence studies of MS published in Medline between 1966 and February 2007. Age- and sex-specific incidence rates were collected from eligible publications. We computed age-adjusted rates using the world population as standard, and assessed differences in rates according to latitude and period of case ascertainment. Additionally, we evaluated the association between period of case ascertainment and the female-to-male ratio.

RESULTS

The overall incidence rate of MS was 3.6 cases per 100,000 person-years (95% CI 3.0, 4.2) in women and 2.0 (95% CI 1.5, 2.4) in men. Higher latitude was associated with higher MS incidence, though this latitude gradient was attenuated after 1980, apparently due to increased incidence of MS in lower latitudes. The female-to-male ratio in MS incidence increased over time, from an estimated 1.4 in 1955 to 2.3 in 2000.

CONCLUSION

The latitude gradient present in older incidence studies of multiple sclerosis (MS) is decreasing. The female-to-male MS ratio has increased in the last five decades.

Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors

As discussed in Part I of this review, the geographic distribution of multiple sclerosis (MS) and the change in risk among migrants provide compelling evidence for the existence of strong environmental determinants of MS, where "environmental" is broadly defined to include differences in diet and other behaviors. As we did for infections, we focus here primarily on those factors that may contribute to explain the geographic variations in MS prevalence and the change in risk among migrants. Among these, sunlight exposure emerges as being the most likely candidate. Because the effects of sun exposure may be mediated by vitamin D, we also examine the evidence linking vitamin D intake or status to MS risk. Furthermore, we review the evidence on cigarette smoking, which cannot explain the geographic variations in MS risk, but may contribute to the recently reported increases in the female/male ratio in MS incidence. Other proposed risk factors for MS are mentioned only briefly; although we recognize that some of these might be genuine, evidence is usually sparse and unpersuasive.

A possible link between multiple sclerosis and Creutzfeldt-Jakob disease based on clinical, genetic, pathological and immunological evidence involving Acinetobacter bacteria

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the nervous system. There is an increasingly likelihood that MS could be triggered/perpetuated by environmental (microbial) agents. Sporadic Creutzfeldt-Jakob disease (sCJD) is a relatively rare but fatal disease, which shows various clinical, genetic, pathological and immunological features through which it resembles a severe form of MS. The disease in some patients with MS may show a rapidly downhill course with death occurring within one to two years and a similar situation occurs in sCJD. The occurrence of these comparative similarities between MS and sCJD could be explained on the basis that both of these conditions might be sharing a common aetiopathogenic factor such as infection by Acinetobacter microbes and this possibility could be investigated further by carrying out immunological studies on a relatively large numbers of patients with MS and CJD.

Bovine Spongiform Encephalopathy, Multiple Sclerosis, and Creutzfeldt-Jakob Disease Are Probably Autoimmune Diseases Evoked byAcinetobacterBacteria

Bovine spongiform encephalopathy (BSE) belongs to a group of conditions named together as transmissible spongiform encephalopathies (TSE). They are fatal neurodegenerative diseases that include "scrapie" in sheep, Creutzfeldt-Jakob disease (CJD) and kuru in humans, and chronic wasting disease in deers. BSE-affected animals suffer from "hindquarters" paralysis, which is also one of the main features of "experimental allergic encephalomyelitis" (EAE). EAE is considered an animal model of multiple sclerosis (MS) and lower limb ataxia is often observed in MS patients. The presence of clinical and histopathological similarities in these diseases suggests a common pathology. Specific brain peptides, which produce EAE, were shown to have "molecular mimicry" with the soil and skin saprophytic microbe, Acinetobacter. BSE-affected animals and patients suffering from MS have been found to have elevated levels of antibodies to both Acinetobacter and Pseudomonas bacteria, as well as autoantibodies to both white and gray matter brain components. The hypothesis is proposed that Acinetobacter/Pseudomonas bacteria may have evoked both BSE and MS through the mechanism of "molecular mimicry" and autoimmunity in a similar way to Streptococcus microbes producing rheumatic fever and Sydenham's chorea. The possibility that CJD patients may show similar features remains to be determined.

A cluster of multiple sclerosis cases in Lysvik in the Swedish county of Värmland

OBJECTIVES

When surveying the county of Värmland in Sweden in order to determine the prevalence of multiple sclerosis (MS), we observed an aggregation of MS cases originating from the parish of Lysvik in the local region called Fryksdalen. Our intention was to analyse this cluster thoroughly, confirming the MS diagnosis and seeing if a hereditary or environmental background was plausible.

METHODS

The medical files were studied and the cases were classified by a neurologist according to Poser's criteria. Hereditary factors were analysed.

RESULTS

Sixteen living cases of MS were found, either living in the parish (n = 6) or born or raised there and had later moved to another place (n = 10). All patients had clinically definite MS. Eleven patients had relatives with MS, all of these being descendants of the Suhoinen family. Another two cases were Suhoinen descendants who did not have relatives with MS. Other common ancestors were also identified. Two cases were adopted. Eleven deceased MS patients from Lysvik were found, 10 of them had Suhoinen ancestry.

CONCLUSION

We report a cluster of MS cases with a common ancestry indicating heredity for MS in 85% of the cases. Lysvik is a parish where Finnish immigration was pronounced in the 17th century and there has been inbreeding to a certain extent through marriage between cousins. Thus, we interpret this aggregation as possibly being genetically based, and neurogenetic studies are now being performed. However, as two of the cases were adopted environmental factors must also be considered.

Multiple Sclerosis

This chapter provides information on the epidemiology of multiple sclerosis (MS), the most common disabling neurological disease in young adults. It describes the clinical and pathologic features of MS and how these features pose challenges for clinical diagnosis and case definition criteria. Information is provided regarding the descriptive epidemiology of MS, including studies of incidence, prevalence, and temporal trends in MS frequency. Also included is a discussion of the interesting geographical features of the MS distribution, including MS disease clusters, the latitude gradient in disease risk, and migrant studies of individuals who move from high-risk to low-risk regions. Other sections of the chapter cover evidence regarding the infectious etiology of MS, including the important role that Epstein-Barr virus appears to play in disease susceptibility. The role of lifestyle factors is receiving increasing emphasis in MS epidemiologic studies, and evidence is summarized regarding the potential role of cigarette smoking, diet, and hormonal factors.

Schistosomiasis decreases central nervous system inflammation and alters the progression of experimental autoimmune encephalomyelitis

A preestablished infection with the parasitic helminth, Schistosoma mansoni, significantly reduced the incidence and delayed the onset of experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice immunized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide. The altered disease progression was not solely due to the induction of a strong Th2 response, since intraperitoneal injection of schistosome eggs did not affect disease development. MOG-specific gamma interferon (IFN-gamma), nitric oxide, and tumor necrosis factor alpha production by splenocytes was significantly reduced in schistosome-infected mice compared to uninfected mice. However, similar levels of interleukin-10 (IL-10) were produced in an antigen-specific manner, suggesting that the induction of antigen-specific responses was not inhibited. Analysis of in vivo cytokine production by real-time PCR indicated that IL-12p40, but not IFN-gamma, transcript levels were dramatically reduced in the spinal cords of schistosome-infected, MOG-immunized mice. Furthermore, analysis of the cellular composition of the spinal cords and brains revealed that a preestablished infection with S. mansoni decreased central nervous system (CNS) inflammation, particularly of macrophages and CD4 T cells. These results suggest that schistosomiasis may negatively regulate the onset of EAE by downregulating the production of proinflammatory cytokines and altering CNS inflammation.

Ecologic analysis of some immune-related disorders, including type 1 diabetes, in Australia: latitude, regional ultraviolet radiation, and disease prevalence

The apparent immune-suppressive effect of ultraviolet radiation (UVR) has suggested that this environmental exposure may influence the development of immune-related disorders. Self-reported prevalence rates of type 1 diabetes mellitus, rheumatoid arthritis (RA), eczema/dermatitis, and asthma, from the 1995 Australian National Health Survey, were therefore examined by latitude and ambient level of UVR. A positive association of type 1 diabetes mellitus prevalence was found with both increasing southern latitude of residence (r = 0.77; p = 0.026) and decreasing regional annual ambient UVR (r= -0.80; p = 0.018); a 3-fold increase in prevalence from the northernmost region to the southernmost region was evident. In contrast, asthma correlated negatively with latitude (r = -0.72; p = 0.046), although the change in asthma prevalence from the north to the south of Australia was only 0.7-fold. For both RA and eczema/dermatitis, there were no statistically significant associations between latitude/UVR and disease prevalence. These ecologic data provide some support for a previously proposed beneficial effect of UVR on T-helper 1-mediated autoimmune disorders such as type 1 diabetes. The inverse association of type 1 diabetes prevalence with UVR is consistent with that previously reported for another autoimmune disease, multiple sclerosis, in Australia, and also with type 1 diabetes latitudinal gradients in the Northern Hemisphere. The finding also accords with photoimmunologic evidence of UVR-induced immunosuppression and may suggest a beneficial effect of UVR in reducing the incidence of such autoimmune conditions. In light of this study, analytic epidemiologic studies investigating risk of immune disorders in relation to personal UVR exposure in humans are required.

Multiple sclerosis is more prevalent in northern New Zealand than previously reported

BACKGROUND

There have been no studies of multiple sclerosis (MS) prevalence from New Zealand (NZ) in the past two decades, and only one in a northern NZ district. Our impression was that the local prevalence of MS was higher than previously published data would suggest. There is limited access to new treatments for MS in NZ.

AIMS

The present paper aims to: (i). measure the prevalence of definite and probable MS in the Bay of Plenty (BOP), a North Island province, (ii). compare this with previous NZ studies, (iii). study the profile of disability in this population-based group and (iv). determine the proportion of MS patients who receive government funding for modern drug treatment (beta-interferons).

METHODS

Patients were identified from a geographically and demographically defined area of the North Island of NZ, using multiple sources of case ascertainment and modern diagnostic criteria. All clinical records were reviewed and data were supported by a telephone interview. All patients' eligibility for -government-funded treatment with beta-interferon was considered.

RESULTS

Eighty-six patients were identified as residents in BOP, NZ, on 15 January 2001. Excluding 'possible' cases, this represented a prevalence of 50/105 (95% confidence interval 40-62/105). Half of the population-based cohort had a disability defined as 'moderate to severe' (i.e. aids needed to walk, unable to take more than a few steps, or worse). Eleven patients (13%) had a primarily progressive form of MS. Eleven patients (13%) had the relapsing--remitting form of the disease and qualified for -government-funded treatment with beta-interferon.

CONCLUSION

The prevalence of MS in the defined region was twice as high as that reported from an adjacent area, the Waikato, 20 years previous. Our data will help to update NZ prevalence statistics and are of direct relevance to current funding issues for modern treatments which, in NZ, are presently limited to a proportion of patients with relapsing- remitting disease.

The vitamin D receptor is necessary for 1alpha,25-dihydroxyvitamin D(3) to suppress experimental autoimmune encephalomyelitis in mice

The active metabolite of vitamin D, 1alpha,25-dihydroxyvitamin D(3), suppresses autoimmune disease in several animal models including experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. The molecular mechanism of this immunosuppression is at present unknown. While 1alpha,25-dihydroxyvitamin D(3) is believed to function through a single vitamin D receptor, there are reports of other vitamin D receptors as well as a "nongenomic" mode of action. We have prepared the EAE model possessing the vitamin D receptor null mutation and determined if 1alpha,25-dihydroxyvitamin D(3) can suppress this disease in the absence of a functional vitamin D receptor. Vitamin D receptor null mice develop EAE although the incidence rate is one-half that of wild-type controls. The administration of 1alpha,25-dihydroxyvitamin D(3) had no significant effect on the incidence of EAE in the vitamin D receptor null mice, while it completely blocked EAE in the wild-type mice. We conclude that 1alpha,25-dihydroxyvitamin D(3) functions to suppress EAE through the well-known VDR and not through an undiscovered receptor or through a "nongenomic" mechanism.

Multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS). Diagnosis rests upon identifying typical clinical symptoms and interpreting supportive laboratory and radiological investigations. The etiology is unknown; however, strong evidence suggests that MS is an autoimmune disease directed against CNS myelin or oligodendrocytes. Genetic factors are important in the development of MS. Contributing environmental determinants (possibly including infectious agents) appear important but remain unidentified. Both cell-mediated and humorally mediated immune mechanisms contribute to pathological injury. Axonal damage occurs in addition to demyelination and may be the cause of later permanent disability. Distinct pathological subtypes may differentiate among patients with MS. Treatment is directed at acute attacks (with corticosteroids) and reduction of attack frequency (primarily with type-1 beta interferons and glatiramer acetate). Research into the causes and treatments of MS has expanded our knowledge of this disease and promises improved care for MS patients in the future.

CD8(+) T cells are not necessary for 1 alpha,25-dihydroxyvitamin D(3) to suppress experimental autoimmune encephalomyelitis in mice

In addition to its role in calcium and phosphorous homeostasis, 1 alpha,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] appears to be a modulator of the immune system. Administration of 1,25-(OH)(2)D(3) prevents disease in several autoimmune animal models, including experimental autoimmune encephalomyelitis (EAE). The vitamin D receptor is believed to mediate this activity. Among cells of the immune system, CD8(+) T cells have the highest levels of the vitamin D receptor. Because CD8(+) T cells have been implicated as both suppressors and effectors of the inflammation associated with multiple sclerosis and EAE, we examined the question of whether the 1,25-(OH)(2)D(3) suppression of EAE occurs through a CD8(+) T cell-dependent mechanism. To test this hypothesis, mice that are homozygous knockouts for the alpha chain of the CD8 receptor and have been characterized as lacking functional CD8(+) T cells (CD8(+) -/-) were provided 1,25-(OH)(2)D(3) in their diet before EAE induction. Although CD8(+) -/- mice fed the same diet lacking 1,25-(OH)(2)D(3) have a high incidence of EAE, EAE did not occur in CD8(+) -/- mice fed the diet containing 1,25-(OH)(2)D(3). We conclude that CD8(+) T cells neither are needed nor do they play a role in the prevention of EAE by 1,25-(OH)(2)D(3).

Prevalence survey of multiple sclerosis in the Australian Capital Territory

AIM

This study sought to obtain an estimate of the prevalence of multiple sclerosis (MS) in the Australian Capital Territory (ACT), a largely urban region that differs climatically and socioeconomically from other Australian cities examined in previous MS surveys.

METHODS

Prevalence day was chosen to coincide with the 1996 National Census. All ACT neurologists' records for the previous 5 years were examined and cases of MS were classified according to the published diagnostic criteria of Rose et al. and Poser et al.

RESULTS

By the criteria of Rose et al., as used in previous Australian surveys of MS, prevalence was 79.9/100,000 (95% confidence interval (CI) = 63.4-99.2) for females, 32.8 (22.7-46.2) for males and 56.7 (43.1-74.1) for all people, standardized to the 1996 population. Standardized to the 1981 population for direct comparison with 1981 surveys in New South Wales, the prevalence of MS in the ACT was still unexpectedly high, particularly for females. Using the criteria of Poser et al., the prevalence of MS standardized to the 1996 population was 70.6/ 100,000 (95% CI = 58.4-85.3) for females, 28.0 (20.3-37.8) for males and 49.5 (42.2-58.2) for all people. There was evidence from a relatively short duration of disease in the ACT sample that some persons with long-standing MS had been missed in the survey and therefore that the prevalence of MS observed in the ACT was an underestimate.

CONCLUSIONS

The survey found an unexpectedly high prevalence of MS in the ACT. Possible reasons for this are discussed. There was no evidence that the advent of magnetic resonance imaging had increased the numbers of persons diagnosed with MS in the present survey.

Mortality from multiple sclerosis and exposure to residential and occupational solar radiation: a case-control study based on death certificates

OBJECTIVES

To explore whether mortality from multiple sclerosis is negatively associated with exposure to sunlight.

METHODS

Two case-control studies based on death certificates were conducted for mortality from multiple sclerosis and non-melanoma skin cancer (as a positive control) to examine associations with residential and occupational exposure to sunlight. Cases were all deaths from multiple sclerosis between 1984 and 1995 in 24 states of the United States. Controls, which were age frequency matched to a series of cases, excluded cancer and certain neurological deaths. The effects of occupational exposure to sunlight were assessed among subjects with usual occupations requiring substantial activity, so as to exclude those whose indoor jobs resulted from disabilities subsequent to the onset of the disease. Multiple logistic regression analyses were applied, with adjustment for age, sex, race, and socioeconomic status.

RESULTS

Unlike mortality from skin cancer, mortality from multiple sclerosis was negatively associated with residential exposure to sunlight (odds ratio (OR)=0.53 (multiple sclerosis) and OR=1.24 (skin cancer)). Odds ratios for the highest occupational exposure to sunlight were 0.74 (95% confidence interval (95% CI) 0.61 to 0.89) for mortality from multiple sclerosis, compared with 1.21 (1.09 to 1.34) for mortality from non-melanoma skin cancer. The OR was 0.24 for the combined effect of the highest levels of residential and occupational exposure to sunlight on multiple sclerosis, compared with an OR of 1.38 for skin cancer.

CONCLUSIONS

In this exploratory study, mortality from multiple sclerosis, unlike mortality from skin cancer, was negatively associated with both residential and occupational exposure to sunlight.

Susceptibility to multiple sclerosis: interplay between genes and environment

Multiple sclerosis is a complex trait of unknown etiology. Epidemiological data have shown that susceptibility to multiple sclerosis is determined by both genetic and environmental factors. It is unknown whether the clinical subcategories of multiple sclerosis are separate diseases with separate etiologies and causes. Recent theories of the pathogenesis of multiple sclerosis and candidate genes are discussed. Other potential nonchromosomal factors involved in multiple sclerosis susceptibility such as mitochondrial DNA and viral factors such as Chlamydia pneumoniae are reviewed.