Susceptibility to multiple sclerosis: interplay between genes and environment

A narrative review of psoriasis and multiple sclerosis: links and risks

The association of psoriasis (PsO) with other autoimmune and autoinflammatory diseases has long been a topic of interest. Although previous studies have attempted to clarify the specific relationship between PsO and multiple sclerosis (MS), it remains obscure, with limited and conflicting evidence regarding a link between the two entities. Herein, we review the etiology, pathogenesis, and treatment of each disease and present the available literature to-date regarding a possible relationship between PsO and MS. We conclude that further study is necessary to discern whether there may be a significant relationship between PsO and MS. In the meantime, clinicians may find it appropriate to screen for MS in patients with PsO, allowing for timely referral to a neurologist should it be necessary.

Effect of interferon-β1α therapy on multiple sclerosis based on gadolinium-enhancing or active T2 magnetic resonance imaging outcomes: a meta-analysis

OBJECTIVES

Interferon-beta1alpha (IFN-β1α) is widely used to modify the course of relapsing-remitting multiple sclerosis. However, many patients have relapses. The purpose of this study was to evaluate magnetic resonance imaging (MRI) as a predictor of IFN-β1α treatment efficacy in patients with MS.

METHODS

PubMed, Embase, and the Cochrane Library were searched to identify eligible studies. Manual searches were also conducted. All eligible trials included MS patients who received IFN-β1α based on gadolinium-enhancing or active T2 MRI lesions for determination of relapse rates.

RESULTS

Of 499 identified studies, we included 10 trials reporting data on 6,037 MS patients. IFN-β1α therapy significantly reduced the risk of relapse (RR: 0.87; 95% confidence intervals (CI): 0.76-0.99; p = 0.032). Furthermore, baseline median T2 lesion volume was found to be related to IFN-β1α therapy and relapse (p = 0.018). Subgroup analysis suggested that IFN-β1α therapy was associated with reduced risk of relapse (RR: 0.82; 95%CI: 0.71-0.94; p = 0.005 versus placebo). However, there was no significant difference in the risk of relapse compared to treatment with low dose IFN-β1α (RR: 0.93; 95%CI: 0.80-1.08; p = 0.337) or glatiramer acetate (RR: 0.93; 95%CI: 0.77-1.14; p = 0.506). Finally, IFN-β1α therapy significantly increased the risk of injection-site disorders, influenza-like syndrome, and alanine transferase elevation.

DISCUSSION

Effects of IFN-β1α therapy are associated with a statistically significant impact on baseline median T2 lesion volume. However, the safety outcomes are significantly worse in patients who receive IFN-β1α therapy.

Heavy metals, organic solvents, and multiple sclerosis: An exploratory look at gene-environment interactions

Exposure to heavy metals and organic solvents are potential etiologic factors for multiple sclerosis (MS), but their interaction with MS-associated genes is under-studied. The authors explored the relationship between environmental exposure to lead, mercury, and solvents and 58 single-nucleotide polymorphisms (SNPs) in MS-associated genes. Data from a population-based case-control study of 217 prevalent MS cases and 496 age-, race-, gender-, and geographically matched controls were used to fit conditional logistic regression models of the association between the chemical, gene, and MS, adjusting for education and ancestry. MS cases were more likely than controls to report lead (odds ratio [OR] = 2.03; 95% confidence interval [CI]: 1.07, 3.86) and mercury exposure (OR = 2.06; 95% CI: 1.08, 3.91). Findings of potential gene-environment interactions between SNPs in TNF-α, TNF-β, TCA-β, VDR, MBP, and APOE, and lead, mercury, or solvents should be considered cautiously due to limited sample size.

Interaction of HLA-DRB1*1501 and TNF-Alpha in a Population-based Case-control Study of Multiple Sclerosis

This study was conducted to determine whether single nucleotide polymorphisms (SNPs) in nine genes (human leukocyte antigen (HLA), T cell receptor beta (TCA receptor β), tumor necrosis factor α (TNF α), tumor necrosis factor β (TNF β), apolipoprotein E (APOE), interleukin 7 receptor alpha chain (IL7RA) interleukin 2 receptor alpha chain (IL2RA) myelin basic protein (MBP) and vitamin D receptor (VDR)) associated with multiple sclerosis (MS) could be replicated in a population-based sample, and to determine if these associations are modified by presence of HLA DRB1*1501. DNA was available from 722 individuals (223 with MS and 499 controls) who participated in a population-based case-control study. Cases and controls were matched on ancestry, age, gender and geographic area. HLA DRB1*1501 risk allele (T) was confirmed in this population using a genotypic test, controlling for multiple comparisons. Examining the effect of each SNP in the presence or absence of the HLA DRB1*1501 risk allele identified significant associations with TNF α -1031 (rs1799964) among those without the HLA risk allele. No additional interactions were significant in a cases-only analysis. Our results indicate that an interaction between SNPs in TNF α and HLA DRB1*1501 may influence the risk of developing MS.

HLA associations with multiple sclerosis in Greece

BACKGROUND

Multiple sclerosis (MS) is a demyelinating inflammatory disease of the central nervous system originated by a complex interplay of environmental and genetic factors. The association of MS with the human leukocyte antigen (HLA) class II alleles was investigated in MS patients in northwest Greece, in the geographical region of Epirus.

OBJECTIVE

Our aim was to estimate the prevalence of the HLA-DRB1*1501, HLA-DQB1*0602 and HLA-DQA1*0102 alleles, consisting the most common susceptibility haplotype in North European and North American Caucasians.

METHODS

We studied 126 MS patients and 93 age and sex matched healthy controls. HLA typing was performed by a polymerase chain reaction (PCR) amplification with sequence-specific primers (PCR-SSP) method.

RESULTS

We found that HLA-DRB1*1501, HLA-DQB1*0602 and HLA-DQA1*0102 alleles were significantly more frequent among patients (34% versus 11%, p=0.00015; 69% versus 51%, p=0.01; 76% versus 55%, p=0.002, respectively). HLA-DRB1*1501, HLA-DQB1*0602, HLA-DQA1*0102 haplotype was significantly more common among patients (p=0.00067). HLA-DRB1*1501 and HLA-DQB1*0602 alleles were more frequently detected in patients with initial symptoms from the brainstem or the cerebellum (p=0.024). No significant correlation was observed among these alleles with sex, disease clinical course, or age at onset.

CONCLUSION

This is the first study to investigate genetic susceptibility to MS in Greece. Our results are in line with previous reports in North European and North American patients.

Monounsaturated fatty acids in blood cell membranes from patients with multiple sclerosis

The aim of this study was to investigate whether blood cell membrane monounsaturated fatty acids were associated with inflammation and disease outcome in patients with multiple sclerosis. The fatty acid composition in peripheral blood mononuclear cell and red blood cell membranes from 26 patients and 25 controls were determined by gas chromatography. Results showed positive associations between C-reactive protein and C16:1n-7, C18:1n-7, and C24:1n-9 in membranes from controls only. In general, C18:1n-9 and C20:1n-9 showed inverse correlations, while C16:1n-7 and C18:1n-7 showed positive correlations with disease outcome. Multiple sclerosis has a known inflammatory component. There is scarcity of literature on the role of monounsaturated fatty acids in inflammation, but results from this study suggested an association in healthy subjects between monounsaturated fatty acids and C-reactive protein, even at physiologically low levels. This association was not found in the plasma from patients. Furthermore, the n-9 and n-7 fatty acids played different roles in disease outcome, and therefore warrant inclusion, together with polyunsaturated fatty acids when investigating the inflammatory aspects of the disease.

Use of health information in air pollution health research: past successes and emerging needs

In September 2006, the US Environmental Protection Agency and the US Centers for Disease Control (CDC) co-organized a symposium on "Air Pollution Exposure and Health." The main objective of this symposium was to identify opportunities for improving the use of exposure and health information in future studies of air pollution health effects. This paper deals with the health information needs of such studies. We begin with a selected review of different types of health data and how they were used in previous epidemiologic studies of health effects of ambient particulate matter (PM). We then examine the current and emerging information needs of the environmental health community, dealing with PM and other air pollutants of health concern. We conclude that the past use of routinely collected health data proved to be essential for activities to protect public health, including the identification and evaluation of health hazards by air pollution research, setting standards for criteria pollutants, surveillance of health outcomes to identify incidence trends, and the more recent CDC environmental public health tracking program. Unfortunately, access to vital statistics records that have informed such pivotal research has recently been curtailed sharply, threatening the continuation of the type of research necessary to support future standard setting and research on emerging exposure and health problems (e.g. asthma, multiple sclerosis, diabetes, and others), as well as our ability to evaluate the efficacy of regulatory and other prevention activities. A comprehensive devoted effort, perhaps new legislation, will be needed to address the standardization, centralization, and sharing of data sets, as well as to harmonize the interpretation of confidentiality and privacy protections across jurisdictions. These actions, combined with assuring researchers and public health practitioners appropriate access to data for evaluation of environmental risks, will be essential for the achievement of our environmental health protection goals.

Clinical features of patients with multiple sclerosis from a survey in Shanghai, China

Objective

To describe clinical features of patients with multiple sclerosis (MS) in Shanghai, China.

Methods

Prevalent patients with MS were identified and investigated by a network of physicians in 11 districts of Shanghai during the period from 1 September 2004 to 31 August 2005. Admission registries of each hospital in the study area were checked systematically for patients with a diagnosis of MS, neuromyelitis optica or other demyelinating disorders. All patients with collected information were evaluated by four senior neurologists according to the McDonald criteria.

Results

There were 249 (146 female and 103 male) patients with a confirmed MS diagnosis, at a female-to-male ratio of 1.4. The mean age at onset of MS was 37.4 years for the 249 patients with MS and, on the prevalence day, 42.7 years. The most frequent location of clinical MS lesions in the central nervous system was the spinal cord (61%), followed by the cerebrum (55%) and optic nerves (41%). Nearly all (96%) of the patients with MS had been examined by magnetic resonance imaging, and 226 (94%) patients of those examined were suggestive of MS. No family history of MS was found in any of the patients. Most (86%) of the patients had no or mild disability on the prevalence day (31 December 2004). Almost all (96%) patients with MS had been treated with corticosteroids.

Conclusion

Clinical features of patients with MS are described based on the information from the largest case series reported among Chinese. Comparisons and discussions are made with findings from the other populations.

Autoimmune disease in families with multiple sclerosis: a population-based study

BACKGROUND

Evidence of an association between multiple sclerosis (MS) and other autoimmune diseases would substantiate the hypothesis that MS is an autoimmune disease, and implicate a common mechanism. We aimed to investigate and compare the rate of autoimmune disease in MS patients, in their first-degree relatives, and in their unrelated spouses.

METHODS

We used data from a national, multicentre, population-based sample to investigate the rate of autoimmune disease in 5031 MS patients, 30 259 of their first-degree relatives, and 2707 spousal controls. We asked patients and controls whether they had any of ten autoimmune diseases: Crohn's disease, ulcerative colitis, rheumatoid arthritis, type 1 diabetes, psoriasis, pernicious anaemia, systemic lupus erythematosus, autoimmune thyroid disease, vitiligo, and myasthenia gravis. MS probands were also asked whether their first-degree relatives had Crohn's disease, ulcerative colitis, rheumatoid arthritis, or type 1 diabetes.

FINDINGS

After correction for age and sex, we did not identify any increased risk of autoimmune diseases in MS patients compared with their spousal controls (odds ratio [OR]=1.07, 95% CI 0.86-1.23, chi(2)=0.47, p=0.49), or in the first-degree relatives of MS probands compared with controls (OR=0.89, 0.63-1.17, chi(2)=1.11, p=0.29). However, the reported frequency of autoimmune diseases did differ according to the sex of the interviewee (female vs male patients chi(2)=92.2, p<0.0001; female vs male spousal controls chi(2)=87.1, p<0.0001). MS patients had slightly higher rates of thyroid disease and pernicious anaemia than did controls, which is consistent with MHC associations for these diseases, but this effect disappeared when results were adjusted for sex. For eight other diseases the rates were similar in MS patients and controls. Families with multiple cases of MS were no more likely to report autoimmune diseases than families with single MS cases.

INTERPRETATION

When data were adjusted for sex, no excess of common autoimmune diseases could be identified in MS patients or their families, including multicase pedigrees. Our results suggest that women are more aware of family medical histories than men, which emphasises the potential for ascertainment bias in unstratified data for a sex-limited disease. Family histories should thus be taken from male patients in the presence of a spouse.

A follow-up study of Nordic multiple sclerosis candidate gene regions

In this study, the results from three Nordic linkage disequilibrium screens in multiple sclerosis (MS) were investigated, in a new sample set of 314 Nordic MS trios from Denmark, Norway, Sweden and Iceland. Among 30 non-HLA and two HLA microsatellite markers individually genotyped, eight markers displayed distorted transmission with uncorrected P-value <0.05, ranked in this order: D6S2443 (6p21.32, HLA class II) (P corrected =0.01), D2S2201 (2p24), D19S552 (19q13), D3S3584 (3q21), D17S975 (17q11), D1S2627 (1p22), D6S273 (6p21.33, HLA class III) and D12S1051 (12q23). These non-HLA regions need further investigation as possible MS candidate gene regions in our population. Multiple Sclerosis 2007; 13: 584-589. http://msj.sagepub.com

HLA-DR15 haplotype and multiple sclerosis: a HuGE review

An association between multiple sclerosis (MS) and the human leukocyte antigen (HLA) complex, a dense cluster of genes on the short arm of chromosome 6, was first noted over 30 years ago. In Caucasian populations of Northern European descent, the DR15 haplotype (DRB1*1501-DQA1*0102-DQB1*0602) has been hypothesized to be the primary HLA genetic susceptibility factor for MS. However, studies of other populations have produced varying results. Thus, the authors reviewed the literature for articles on the association between the DR15 haplotype and MS. They identified 72 papers meeting the inclusion criteria: human genetic studies written in English that were published between 1993 and 2004 and that reported allele frequencies for HLA-DRB1*1501, HLA-DQA1*0102, or HLA-DQB1*0602 or the frequency of the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. Most of the studies identified used a case-control design (n = 60), while the remainder used a family-based design (n = 22). In most of these papers, investigators reported a higher frequency of the DR15 haplotype and/or its component alleles among MS cases than among controls. However, the authors' confidence in these results is tempered by factors related to study design that may have biased the outcomes.

No effect of APOE and PVRL2 on the clinical outcome of multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for its variability in disease outcome. Apolipoprotein E (APOE) is involved in neuronal remodelling and several studies have attempted to examine the effect of APOE on MS disease severity, but its function in modifying the course of MS is controversial. It has been suggested recently that PVRL2, not APOE, is the locus on chromosome 19 which influences clinical outcome of MS. A cohort of sporadic MS cases, taken from opposite extremes of the putative distribution of long-term outcome using the most stringent clinical criteria to date, was used to determine the role of APOE and PVRL2 on MS disease severity. The MS cases selected represent the prognostic best 5% (benign MS) and worst 5% (malignant MS) of cases in terms of clinical outcome assessed by the EDSS. Genotyping the two sets of MS patients (112 benign and 51 malignant) and a replication cohort from Sardinia provided no evidence to suggest that APOE or PVRL2 have any outcome modifying activity. We conclude that APOE and PVRL2 have little or no effect on the clinical outcome of MS.

Differential twin concordance for multiple sclerosis by latitude of birthplace

OBJECTIVE

To address the inconsistency in the reported concordance of multiple sclerosis (MS) among twins by zygosity, sex, and latitude.

METHODS

Four hundred eighteen medically documented monozygotic (MZ) and 380 same-sex dizygotic (DZ) pairs were ascertained from 1980 to 1992 and followed. The study population was representative of twins with multiple sclerosis. Twins from Canada and adjacent US states (at or above 41-42 degrees N) were considered "northern," and ancestry was dichotomized from descent from high-risk populations. Diagnosis before median age 29.3 years was considered "early."

RESULTS

The MZ/DZ concordance ratio was 2.9 (95% confidence interval [CI], 1.0-8.9) among men and 2.6 (95% CI, 1.5-4.5) among women. The average age at northern diagnosis was independent of ancestry and 2 years earlier for both MZ (p < 0.02) and DZ (p < 0.01) patients. Among DZ twins, concordance was independent of all characteristics. Among MZ twins, concordance was 1.9 times (95% CI, 1.2-3.2) greater among northern twins, 1.9 (95% CI, 1.1-3.6) times greater among twins with high-risk ancestry, and 2.1 (95% CI, 1.2-3.6) times greater if diagnosis was early. Ancestry and early diagnosis made independent significant contributions to the differential concordance by latitude.

INTERPRETATION

Multiple sclerosis is similarly heritable by sex, and the apparent variation in MZ concordance by latitude is influenced by environmental and genetic factors.

Altered naive CD4 and CD8 T cell homeostasis in patients with relapsing-remitting multiple sclerosis: thymic versus peripheral (non-thymic) mechanisms

We have reported previously that naive T cells from relapsing-remitting multiple sclerosis (RRMS) patients have T cell receptor (TCR) repertoire shifts, but the basis of these TCR repertoire shifts was uncertain. Here, we questioned whether RRMS patients have altered naive CD4 and CD8 T cell homeostasis by studying homeostatic proliferation and thymic production in RRMS patients and healthy controls. We measured thymic production by quantifying signal joint T cell receptor excision circles (sjTRECs). Both naive T subsets from controls showed an age-associated decrease in sjTRECs, i.e. evidence of progressive thymic involution, but we detected no age-associated decrease in sjTRECs in RRMS patients. Instead, naive CD8 T cells from patients had lower sjTRECs (P = 0.012) and higher Ki-67 proliferation levels (P = 0.04) than controls. Naive CD4 T cell sjTRECs did not differ between patients and controls. However, in RRMS these sjTRECs correlated strongly with CD31, a marker expressed by newly generated CD4 T cells but not by naive CD4 T cells that have undergone homeostatic proliferation. HLA-DR2 positivity correlated negatively with naive CD4 T cell CD31 expression in RRMS (P = 0.002). We conclude in RRMS that naive T subsets have homeostatic abnormalities due probably to peripheral (non-thymic) mechanisms. These abnormalities could have relevance for MS pathogenesis, as naive T cell changes may precede MS onset.

Update on depression in neurologic illness: stroke, epilepsy, and multiple sclerosis

The risk of depression is increased in chronic neurologic illness and can adversely affect the course of disease. Recent literature is reviewed for depression in stroke, epilepsy, and multiple sclerosis. Depression can share pathophysiologic aspects of the comorbid illness, such as neurotransmitter pathway disturbances, hypothalamus-pituitary-adrenal pathway disturbances, and changes in immunologic function. Depression also can be a psychologic reaction to the burden of the neurologic condition. Risk factors for development of depression are reviewed. Depression and other medical conditions can have shared symptoms (eg, fatigue, psychomotor retardation) that can complicate the diagnosis of depression in neurologic illness. Proper selection of antidepressant treatment is necessary to avoid worsening the neurologic disorder.

Population frequency of HLA haplotypes contributes to the prevalence difference of multiple sclerosis in Ireland

BACKGROUND

A recent epidemiological study of multiple sclerosis in County Donegal in the northwest of Ireland and County Wexford in the southeast found a significant prevalence difference of 63.9/100,000 (95% CI 49.3-82.7/100,000) between the two regions (Z = 3.94, p <or= 0.001). County Donegal had a higher prevalence rate than County Wexford (184.6/100,000 vs. 120.7/ 100,000). The aim of this paper is to examine whether the MS prevalence difference between the two counties is due to population differences in the genetic predisposition to MS.

METHODS

Seventy-three MS patients from County Donegal and 45 from County Wexford participated in the study and 200 control subjects were enrolled from each county. Blood samples from both MS populations and control populations were HLA typed for DRB1 and DQB1 alleles.

RESULTS

The strong association with the development of MS and the HLA DRB1*1501 and DQB1*0602 phenotypes was confirmed in both patient populations relative to controls. The Donegal sample control population also had a significantly higher carriage rate of the HLA DRB1*1501 - DQB1*0602 haplotype relative to the Wexford sample control population (chi(2) = 5.02, p <or= 0.05,OR = 1.616, CI 1.060-2.464, p = 0.05).

CONCLUSION

Although the numbers tested in this study were small the results suggest one of the factors accounting for the difference in MS prevalence across the island of Ireland is likely to be variation in the genetic predisposition to MS within the Irish population.

Clinical multiple sclerosis occurs at one end of a spectrum of CNS pathology: a modified threshold liability model leads to new ways of thinking about the cause of clinical multiple sclerosis

Multiple sclerosis (MS) is a complex trait, the causes of which are elusive. A threshold liability model influences thinking about the causes of this disorder. According to this model, a population has a normal distribution of genetic liability to MS. In addition, a threshold exists, so that MS begins when an individual's liability exceeds the MS threshold; environmental and other causative factors may increase or decrease an individual's MS liability. It is argued here, however, that this model is misleading, as it is based on the incorrect assumption that MS is a disorder that one either has or does not have. This paper hypothesizes, instead, that patients with a diagnosis of MS share identical CNS pathology, termed MS pathology, with some individuals who have a diagnosis of possible MS and with some apparently healthy individuals, who may never have a diagnosis of MS. In order to accommodate this hypothesis, the current threshold liability model is modified as follows. (1) In addition to a normal distribution of MS liability within a population, a spectrum of MS pathology occurs in some who have a high MS liability. (2) A clinical MS threshold exists at a point on this liability distribution, where the burden and distribution of MS pathology permits a diagnosis of clinical MS. (3) Additional thresholds exist that correspond to a lower MS liability and a lesser burden of MS pathology than occur at the clinical MS threshold. This modified threshold model leads to the postulate that causes act at various time points to increase MS liability and induce MS pathology. The accumulation of MS pathology sometimes leads to a diagnosis of clinical MS. One implication of this model is that the MS pathology in clinical MS and in some with possible MS differs only in the extent but not in the type of CNS injury. Thus, it may be possible to obtain insight into the causative environmental factors that increase MS liability and induce MS pathology by focusing on patients who have clinical MS; some environmental factors that induce new lesions in patients with clinical MS may be identical to those that induce MS pathology in genetically susceptible individuals who do not have clinical MS. Identification of these causative factors has importance, as specific treatment may prevent the accumulation of MS pathology that leads to the significant CNS damage associated with clinical MS.

Parental age, family size, and risk of multiple sclerosis

BACKGROUND

Family structure, such as having siblings, provides proxy measures for a variety of characteristics relevant to disease risk. The etiology of multiple sclerosis (MS) is not well defined and analysis of family structure may provide etiologic clues. We conducted a case-control study to examine possible associations.

METHODS

Using the Swedish Inpatient Register, we identified 4443 patients with a diagnosis of MS. From the general Swedish population, using birth and death registers, we selected 24,194 controls with similar characteristics for year, county of birth, and survival until at least age at diagnosis of the matched cases. The Multi-Generation Register linked data on siblings and parents. The Census provided father's social class based on occupation.

RESULTS

Having 3 or more younger siblings, compared with none, produced an adjusted odds ratio (OR) for MS (with 95% confidence interval) of 0.80 (0.70-0.92) (adjusting for number of siblings, twins, maternal and paternal age, parental MS, sex, father's social class, county and year of birth). With 3 or more older siblings, the adjusted OR was 0.83 (0.72-0.96). Different-sex twin pairs compared with singletons had an OR of 0.59 (0.37-0.95) for MS. The risk of MS increased steadily with father's age but not mother's age, up to 2.00 (1.35-2.96) for 51- to 55-year-old fathers (compared with 21- to 25-year-old fathers).

CONCLUSIONS

Parents who have offspring with MS may have subtly impaired fertility. The unexpected association with paternal age may be the result of an increased risk of accumulating germ cell mutations among older men.

Ctla4 and multiple sclerosis in the Italian population

CTLA4 protein is a receptor molecule that plays a critical role as a negative regulator of the immune response. Therefore, genetic variations in CTLA4 may confer susceptibility to autoimmune diseases such as multiple sclerosis (MS). In order to investigate the association of two CTLA4 polymorphisms (+49 A/G and -318 C/T) with multiple sclerosis, sporadic MS patients and healthy controls from Italy were genotyped through direct DNA sequencing. Considering single-loci variations, no differences in the allelic and genotypic frequencies between patients and controls were found. However, considering a putative interaction at the two loci, the T/G combination was more frequently observed in patients than in controls. This result suggests that this allelic combination of the CTLA4 polymorphisms may be involved in the susceptibility to MS in the Italian population.

Challenges in Addressing Community Concerns Regarding Clusters of Multiple Sclerosis and Potential Environmental Exposures

Citizens living around hazardous waste sites in the USA have expressed concern to public health officials at the local, state and federal level about a perceived high prevalence of multiple sclerosis (MS) in their communities. Many believe the occurrence of the disease is directly linked to exposure to chemical agents from the nearby hazardous waste site. Although the public's concern regarding these clusters should be addressed, epidemiologists have long known that evaluating perceived clusters is rarely fruitful for identifying an etiologic agent. In order to adequately address concerns regarding clusters of MS, as well as examining the role of environmental exposures and genetic susceptibility in the causal mechanism of disease, several activities need to be conducted including characterizing the occurrence of disease, developing a standardized case definition and establishing partnerships to develop innovative research techniques. Only with collaboration across disciplines and lessons learned from past research will we be able to effectively guide research efforts directed at determining the etiology of this disease.

An MRI study of Chlamydia pneumoniae infection in Italian multiple sclerosis patients

We amplified sequences of the Chlamydia pneumoniae (CP) major-outer membrane protein in the cerebrospinal fluid (CSF) from 23 of 107 (21.5%) relapsing-remitting or secondary progressive multiple sclerosis (MS) patients and two of 77 (2.6%) patients with other neurological diseases (OND) (P = 0.00022). CP+ patients showed magnetic resonance imaging (MRI) evidence of more active disease (P = 0.02) compared to CP- MS patients and tended to have an anticipation of age at disease onset (32.3 +/- 12 versus 28.5 +/- 10 years; P = ns) causing a longer disease duration (7.5 +/- 5 versus 4.4 +/- 4 years; P = 0.016) at the time of clinical evaluation. These findings, although indirectly, suggest that CP infection of the central nervous system (CNS) might affect disease course in a subgroup of MS patients.

Effects of the multiple sclerosis associated −330 promoter polymorphism in IL2 allelic expression

The -330 IL2 gene promoter polymorphism has been associated with multiple sclerosis (MS) [J. Neuroimmunol. 119 (2001) 101], but the basis underlying this association remains unknown to date. In the present work, we have found that IL2 promoter-luciferase constructs, transfected in Jurkat cell line, showed twofold higher levels of gene expression in the -330 G allele. However, the transcriptional effect of this polymorphism in lymphocytes showed that the G allele was related to lower expression of IL2. This difference increased in the patient group. Divergence between in vivo and in vitro influence of the -330 IL2 promoter polymorphic site suggests the existence of additional unknown polymorphisms affecting gene regulation. Our data show an increased IL2 expression among GT and TT genotypes previously associated with susceptibility to MS.

Identical twins discordant for multiple sclerosis have a shift in their T-cell receptor repertoires

CD4 T-cells have an important role in the autoimmune response in multiple sclerosis (MS). We investigate the possibility that a shift occurs in the T-cell receptor (TR) repertoire of identical twins discordant for MS. We compare the CDR3 spectratype distributions of 24 different TR V beta (TRBV) segments in naïve CD4 T-cells from discordant MS twins and from healthy identical twins. We also compare the CDR3 spectratype distributions in unrelated healthy pairs, formed by combining members of different healthy twins, with the CDR3 spectratype distributions in unrelated pairs of MS patients and in unrelated pairs of their apparently healthy cotwins, formed by combining members of different discordant twins. We use the correlation coefficient (r-value) as a measure of similarity of CDR3 spectratypes in each pair, and we test for the significance of the difference between r-values from the different pairs. We observe that the r-value for the CDR3 spectratype distributions among discordant twins differs significantly from the corresponding r-value for the healthy twins for two TRBV segments. Further, the r-values, for both the unrelated MS patient pairs and the unrelated pairs of their apparently healthy cotwins, differ significantly from the r-values for healthy unrelated pairs of individuals. We conclude that both the MS patients and their apparently healthy cotwins have shifts in their CDR3 repertoires. Because we study naïve CD4 T-cells, we postulate that CDR3 repertoire shifts precede MS and predispose to MS, but are unlikely to be sufficient to cause MS.

The initiation of multiple sclerosis: a new infectious hypothesis

Both genetic and environmental factors cause multiple sclerosis (MS). Few genes have been identified, however, and environmental factors remain elusive. Some postulate an infectious cause, but no pathogens are reproducibly demonstrable in CNS lesions. I postulate that the CNS is not the infectious target in MS, but propose a two-hit infectious hypothesis focusing on nai;ve CD4 T-cells that initiate demyelination: (1) Various common viruses infect the thymus during childhood (first hit) and enhance nai;ve CD4 T-cell reactivity to CNS autoantigens; (2) Heterogeneous pathogens fully activate these T-cells during adulthood (second hit) to initiate myelin injury. The novel concept of thymic infection provides insight into the nature of some susceptibility genes, helps explain the high discordance rates in genetically susceptible individuals, and suggests it is futile to search for pathogens in MS lesions. Pathogen heterogeneity, i.e., the lack of a single infectious cause, implies there can be no simple therapies to prevent or treat MS.

Detection of infectious agents in brain of patients with acute hemorrhagic leukoencephalitis

Acute hemorrhagic leukoencephalitis (AHL) is a rare and usually fatal disorder characterized clinically by an acute onset of neurologic abnormalities. It may occur in association with a viral illness or vaccination. Radiology and brain biopsy are essential for the diagnosis. The etiology of AHL is unclear. We postulated that viral/bacterial infection might be responsible, directly or through an immune-mediated mechanism, for this acute inflammatory myelinopathy. Fifteen cases of AHL were studied. Infectious agents, including varicella zoster virus (VZV), herpes simplex virus (HSV), human herpes virus-6 (HHV-6), cytomegalovirus, Epstein-Barr virus, and Mycoplasma, were investigated in brain specimens using the polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, and immunohistochemistry. Using PCR, HSV DNA was found in four cases, VZV DNA in two, and HHV-6 DNA in one. Among the control cases, two were HSV DNA positive. Further investigation to detect HSV RNA and antigens in HSV DNA-positive cases revealed that two cases with AHL were both HSV RNA and antigen positive. AHL is a hyperacute disease, which is considered the most acute form of acute disseminated encephalomyelitis (ADEM). Our findings suggests that a viral infection may be implicated in its pathogenesis, most likely through an indirect mechanism; however, as only a few cases of this rare disease were examined, statistical significance was not achieved. As a number of patients with disorders of the ADEM group may progress to develop multiple sclerosis (MS), we argue that an organism that has produced the former may remain in the brain tissue and be subsequently involved in the production of a self-sustained disorder such as MS.

Prospective study on the relationship between infections and multiple sclerosis exacerbations

One of the characteristics of multiple sclerosis is the unpredictable occurrence of exacerbations and remissions. These fluctuations in disease activity are related to alterations in (auto-)immune activity. Exacerbations lead to short-term morbidity, but may also influence long-term disability. This longitudinal study in 73 patients with relapsing-remitting multiple sclerosis assessed the contribution of systemic infections to the natural course of exacerbations. In addition, we analysed whether infections lead to an increase in the number of gadolinium-enhancing lesions. A total of 167 infections and 145 exacerbations were observed during 6466 patient weeks. During a predefined at-risk period (ARP) of 2 weeks before until 5 weeks after the onset of a clinical infection (predominantly upper airway infections), there was an increased risk of exacerbations (rate ratio 2.1), which is in accordance with previous studies. Exacerbations with onset during the ARP led more frequently to sustained deficit [increase of > or =1 Expanded Disability Status Scale (EDSS) point or > or =0.5 above EDSS 5.5 for >3 months] than exacerbations with onset outside the ARP, with a rate ratio of 3.8. Minor and major exacerbations were equally distributed between the ARP and non-ARP onset groups. ARP exacerbations were associated with significantly higher plasma levels of the inflammatory marker soluble intracellular adhesion molecule 1 than non-ARP exacerbations, indicating relatively enhanced immune activation during ARP relapses. Three serial MRI scans were performed after the onset of an infection over a 6-week period. There was no difference in the number of gadolinium-enhancing lesions between the three time points. In conclusion, exacerbations in the context of a systemic infection lead to more sustained damage than other exacerbations. There is no indication that this effect occurs through enhanced opening of the blood-brain barrier.

Microchimerism in autoimmunity and transplantation: potential relevance to multiple sclerosis

Microchimerism (MC) is the stable presence of small numbers of non-host cells and appears to be commonly present in parous women. There are several methods of detecting microchimerism and each has advantages for different types of studies, but the risk of contamination and the differing levels of sensitivity lead to difficulties in estimating the proportion of individuals that are microchimeric. Recent observations of an increased frequency of microchimerism in women with scleroderma and Hashimoto's thyroiditis suggest that microchimerism may increase the risk of developing autoimmune disease. Inferences regarding autoimmunity are drawn from the immunological effects of organ and bone-marrow transplantation. Potential research questions regarding microchimerism, human leukocyte antigen (HLA) similarity, and autoimmune diseases in the context of multiple sclerosis (MS) are discussed.

The genetics of complex autoimmune diseases: non-MHC susceptibility genes

Susceptibility to complex autoimmune diseases (AIDs) is a multigenic phenotype affected by a variety of genetic and environmental or stochastic factors. After over a decade of linkage analyses, the identification of non-major histocompatibility complex (non-MHC) susceptibility alleles has proved to be difficult, predominantly because of extensive genetic heterogeneity and possible epistatic interactions among the multiple genes required for disease development. Despite these difficulties, progress has been made in elucidating the genetic mechanisms that influence the inheritance of susceptibility, and the pace of gene discovery is accelerating. An intriguing new finding has been the colocalization of several AID susceptibility genes in both rodent models and human linkage studies. This may indicate that several susceptibility alleles affect multiple AIDs, or alternatively that genomic organization has resulted in the clustering of many immune system genes. The completion of the human genome sequence, coupled with the imminent completion of the mouse genome, should yield key information that will dramatically enhance the rate of gene discovery in complex conditions such as AID susceptibility.

Classification of demyelinating diseases at the interface between etiology and pathogenesis

The classical demyelinating diseases include the 'autoimmune' inflammatory demyelinating diseases, the inflammatory demyelinating diseases of infectious aetiology, and the demyelinating or dysmyelinating diseases of genetic/hereditary background. In addition, primary demyelination is present in other conditions, such as brain ischaemia and intoxication. Irrespective of the primary aetiology, selective demyelination can be mediated through various pathogenetic pathways: the immune-mediated inflammatory pathway; the metabolic pathway; and the ischaemic/excitotoxic pathway. These pathways are only partly segregated with distinct aetiologies of demyelinating diseases, but they also reflect the way in which the patient copes with the disease-inciting event in relation to their particular genetic background. For future therapeutic strategies it will be important to interfere with the specific pathogenetic pathways of demyelination, which may be common to various demyelinating diseases, but may differ in subgroups of patients who suffer from a particular clinical demyelinating disease entity.

Human autoimmunity genes in mice

In the post-genomic era, the expression and investigation of human (auto)immunity genes seems more relevant than ever. The generation of humanized animal models of human diseases will be useful to study the interplay between genetic and non-genetic factors in disease development and may form a basis for the development of new drugs that act more specifically than the ones currently in use. Transgenic mice have been generated that express various human proteins--candidate autoantigens, disease-associated MHC class II molecules, TCRs and/or CD4--in order to study diseases such as rheumatoid arthritis, multiple sclerosis and diabetes.

Corticosteroids or ACTH for acute exacerbations in multiple sclerosis

BACKGROUND

Corticosteroids are often used to improve the rate of recovery from acute exacerbation in multiple sclerosis (MS) patients. However, it is still unclear just how relatively effective these agents are and the type of drug, optimal dose, frequency, duration of treatment and route of administration are unknown.

OBJECTIVES

The object of this review was to determine the efficacy and safety of corticosteroids or ACTH in reducing the short and long term morbidity from MS. Moreover, we wished to examine from indirect comparisons if the effect of corticosteroids is different according to different doses and drugs, routes of administration, length of treatment.

SEARCH STRATEGY

A search strategy developed for the Cochrane MS Group (last searched: June 1999) completed with handsearching and personal contacts with trialists and pharmaceutical companies was used.

SELECTION CRITERIA

All randomised, double-blind, unconfounded trials comparing corticosteroids or ACTH to placebo in patients with MS, treated for acute exacerbations, without any age or severity restrictions, were evaluated.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected articles for inclusion, assessed trials' quality and extracted the data. A third reviewer cross-checked them and disagreements were resolved by a joint discussion.

MAIN RESULTS

Six trials contributed to this review; a total of 377 participants (199 treatment, 178 placebo) were randomised. The drugs analysed were methylprednisolone (MP) (four trials, 140 patients) and ACTH (two trials, 237 patients). Overall, MP or ACTH showed a protective effect against the disease getting worse or stable within the first five weeks of treatment (odds ratio[OR]=0.37, 95% confidence interval [CI] 0.24-0.57) with some but non significant greater effect for MP and intravenous administration. Short (five days) or long (15 days) duration of treatment with MP did not show any significant difference. Only one study (with 51 patients) reported data after one year of follow-up: no difference between oral MP and placebo in the prevention of new exacerbations or improvement in long term disability was detected. No data are available beyond one year of follow-up to indicate whether steroids or ACTH have any effect on long-term progression. One study reported that a short term treatment with high dose intravenous MP was not attended by adverse events. On the contrary, gastrointestinal symptoms and psychic disorders were significantly more common in the oral, high-dose MP than in the placebo group. Weight gain and edema were significantly more frequent in the ACTH group than in controls.

REVIEWER'S CONCLUSIONS

We found evidence favouring the corticosteroid MP for acute exacerbation in MS patients. Data are insufficient to reliably estimate effect of corticosteroids on prevention of new exacerbations and reduction of long-term disability. Studies assessing long term risk/benefit and adverse effects of corticosteroids in MS patients are urgently needed.