APOE genotypes and disease severity in multiple sclerosis

Exploring the causal effects of serum lipids and lipidomes on lewy body dementia: a Mendelian randomization study

Background

Lewy body dementia (LBD) is a neurodegenerative disorder characterized by the accumulation of Lewy bodies, which primarily composed of misfolded alpha-synuclein (αS). The development of LBD and APOE4 subtypes is thought to be associated with disorders of lipid metabolism. In this study, we investigated the causal relationship between serum lipids, liposomes and LBD using a two-sample Mendelian randomization (TSMR) method.

Methods

A TSMR analysis of genome-wide association study (GWAS) data for 8 serum lipids, 179 lipidomes components, LBD and its subtypes was performed, using inverse variance weighted as the primary outcome. To ensure robustness, the sensitivity analyses including MR Pleiotropy RESidual Sum and Outlier, Cochran's test, leave-one-out method and funnel plots were performed.

Results

In this study, we found that low-density lipoprotein cholesterol (LDL-C) (OR=1.45, 95% CI=1.19-1.77, P<0.001) and remnant cholesterol (RC) (OR=2.64, 95% CI=1.64-4.28, P<0.001) had significant positive causal effects on LBD, and RC also had a positive effect on LBD in carriers of the APOE4 gene. The results of lipidome analysis showed that phosphatidylcholine (PC) (O-16:0_20:4) levels (OR=0.86, 95% CI=0.75-0.98, P=0.02) and PC (O-18:1_20:4) levels (OR=0.76, 95% CI=0.65-0.89, P <0.001) had negative causal effects on LBD, whereas phosphatidylinositol (PI) (18:1_20:4) levels had a positive causal effect on LBD (OR=1.19, 95% CI=1.02-1.39, P=0.03). For LBD with APOE4 carriers, high levels of PC (16:1_18:0) and PC (O-18:2_18:1) had a significant positive effect, while high levels of PC (O-16:1_18:0), phosphatidylethanolamine (PE) (O-18:2_18:1), sphingomyelin (SM) (d38:2), and triacylglycerol (TAG) (56:5) significantly reduced the risk. No heterogeneity and horizontal pleiotropy were observed in sensitivity analysis.

Conclusion

Elevated LDL-C and RC levels are significant risk factors for LBD, with RC also impacting APOE4-carrying LBD. Glycerophospholipids play a crucial role in the pathogenesis of LBD, but the specific components that play a role differ from those with the APOE4 carries. These findings highlight the importance of lipid metabolism in LBD and APOE4 subtypes.

Human Leukocyte Antigen and microRNAs as Key Orchestrators of Mild Cognitive Impairment and Alzheimer's Disease: A Systematic Review

The expression of inflamma-miRs and human leukocyte antigen (HLA) haplotypes could indicate mild cognitive impairment (MCI) and Alzheimer's disease (AD). We used international databases to conduct a systematic review of studies on HLA variants and a meta-analysis of research on microRNAs (miRNAs). We aimed to analyze the discriminative value of HLA variants and miRNAs in MCI, AD and controls to evaluate the protective or causative effect of HLA in cognitive decline, establish the role of miRNAs as biomarkers for the early detection of AD, and find a possible link between miRNAs and HLA. Statistical analysis was conducted using Comprehensive Meta-analysis software, version 2.2.050 (Biostat Inc., Englewood, NJ, USA). The effect sizes were estimated by the logarithm base 2 of the fold change. The systematic review revealed that some HLA variants, such as HLA-B*4402, HLA-A*33:01, HLA-A*33:01, HLA-DPB1, HLA-DR15, HLA-DQB1*03:03, HLA-DQB1*06:01, HLA-DQB1*03:01, SNPs on HLA-DRB1/DQB1, and HLA-DQA1, predisposed to cognitive decline before the occurrence of AD, while HLA-A1*01, HLA-DRB1∗13:02, HLA-DRB1*04:04, and HLA-DRB1*04:01 demonstrated a protective role. The meta-analysis identified let-7 and miR-15/16 as biomarkers for the early detection of AD. The association between these two miRNA families and the HLA variants that predispose to AD could be used for the early screening and prevention of MCI.

Management of multiple sclerosis in older adults: review of current evidence and future perspectives

IMPORTANCE

The prevalence of multiple sclerosis (MS) and aging MS patients is increasing worldwide. There is a need to better understand this MS sub-population, which historically is underrepresented in the literature. This narrative review examines the evolving demographics, disease course, and treatments for older adults with MS (OAMS) to address current knowledge gaps and highlight areas critical for future research.

OBSERVATIONS

OAMS populations require special consideration by clinicians. Older individuals have different care needs than individuals with adult onset MS who are mid-life or younger. Comorbidities, an aging immune system, increasing neurodegeneration, decreasing neurologic reserve, changing benefit/risk relationship for disease modifying therapies (DMTs), and wellness require special attention to provide holistic comprehensive care. Active areas of research include potential cessation of DMTs and novel disease targets.

CONCLUSIONS AND RELEVANCE

This review highlights both the current knowledge and information gaps in the literature that are critical to understanding and properly managing OAMS. The aims are to inform MS clinicians in their current practice, as well as inspire future studies which are critical to providing quality and evidence-based care for OAMS.

Shared genetic loci between Alzheimer's disease and multiple sclerosis: Crossroads between neurodegeneration and immune system

BACKGROUND

Neuroinflammation is involved in the pathophysiology of Alzheimer's disease (AD), including immune-linked genetic variants and molecular pathways, microglia and astrocytes. Multiple Sclerosis (MS) is a chronic, immune-mediated disease with genetic and environmental risk factors and neuropathological features. There are clinical and pathobiological similarities between AD and MS. Here, we investigated shared genetic susceptibility between AD and MS to identify putative pathological mechanisms shared between neurodegeneration and the immune system.

METHODS

We analysed GWAS data for late-onset AD (N cases = 64,549, N controls = 634,442) and MS (N cases = 14,802, N controls = 26,703). Gaussian causal mixture modelling (MiXeR) was applied to characterise the genetic architecture and overlap between AD and MS. Local genetic correlation was investigated with Local Analysis of [co]Variant Association (LAVA). The conjunctional false discovery rate (conjFDR) framework was used to identify the specific shared genetic loci, for which functional annotation was conducted with FUMA and Open Targets.

RESULTS

MiXeR analysis showed comparable polygenicities for AD and MS (approximately 1800 trait-influencing variants) and genetic overlap with 20% of shared trait-influencing variants despite negligible genetic correlation (rg = 0.03), suggesting mixed directions of genetic effects across shared variants. conjFDR analysis identified 16 shared genetic loci, with 8 having concordant direction of effects in AD and MS. Annotated genes in shared loci were enriched in molecular signalling pathways involved in inflammation and the structural organisation of neurons.

CONCLUSIONS

Despite low global genetic correlation, the current results provide evidence for polygenic overlap between AD and MS. The shared loci between AD and MS were enriched in pathways involved in inflammation and neurodegeneration, highlighting new opportunities for future investigation.

Association of APOE Serum Levels and APOE ε2, ε3, and ε4 Alleles with Optic Neuritis

Optical neuritis (ON), otherwise known as optical nerve damage, is a term used to describe various environmental and body conditions that lead to optic nerve dysfunction. Neurologists are well aware of conditions that cause optic neuropathy, such as trauma, infections, malnutrition, and various toxins. As optic neuritis is a multifactorial demyelinating or infectious process, genetic predisposition may also influence the progression of optic neuritis. This study aimed to evaluate the association of ON (with and without multiple sclerosis) with APOE alleles and APOE serum levels. We found that the APOE ε3/ε3 genotype was statistically less common in the ON group of males than in the control group (p = 0.045). Moreover, the APOE ε3/ε3 genotype had a 3.7-fold increase in the odds of ON development in males (OR = 3.698; CI: 1.503–9.095; p = 0.004). In contrast, the APOE ε3/ε4 genotype had a 4.1-fold decrease in the odds of ON development in males (OR = 0.242; CI: 0.083–0.704; p = 0.009). APOE serum levels were statistically significantly higher in the ON group than in the control group (p = 0.042). The APOE ε3/ε3 genotype may increase males’ risk of developing ON, while the ε3/ε4 genotype may reduce males’ risk of developing ON.

ε2 , ε3 , and ε4 variants of ApoE; rs2228570 (VDR), rs4588 and rs7041 (VDBP) polymorphisms in patients with multiple sclerosis: A case-control study in Turkish population

AIM OF THE STUDY

Multiple sclerosis (MS) is a degenerative disease characterized by autoimmune demyelination in the central nervous system. Yet, underlined genetics or environmental markers are still controversial. The impact of vitamin D and cholesterol on disease activity has been phrased by many studies; however, the data available for the Turkish population are very limited. This study aimed to investigate the effect of vitamin D-related polymorphisms (VDBP and VDR) and cholesterol-related variants of ApoE on Turkish MS patients.

MATERIALS AND METHODS

Total DNAs were extracted from peripheral blood samples of 51 MS patients and 50 healthy volunteers. rs4588 and rs7041 polymorphisms of VDBP, rs2228570 of VDR, as well as ε2, ε3, and ε4 variants of ApoE, were investigated by RT-PCR. Biochemical parameters which thought to be associated with MS were also measured. Results were evaluated statistically.

RESULTS

Homozygous mutant genotype and G allele of rs2228570 in VDR, as well as heterozygous genotype of rs4588 in VDBP, were found statistically high in patients. Total cholesterol, triglyceride, and LDL-C levels were found significantly high, whereas HDL-C and vitamin D levels were low in patients. An association was found between rs4588 variation and high triglyceride levels. Similar correlations were found between ε2 genotype and low LDL-C level; ε3 genotype and higher LDL-C. Gender, triglyceride, HDL-C, and AA genotype in rs4588 had a significant effect on MS progression.

CONCLUSION

The variations of rs2228570 and rs4588, vitamin D deficiency, and biological parameters related to cholesterol metabolism may be associated with MS risk.

Association of apolipoprotein E and myeloperoxidase genotypes to clinical course of familial and sporadic multiple sclerosis

The importance of apolipoprotein E (ApoE) and myeloperoxidase (MPO) genotypes in the clinical characteristics of multiple sclerosis (MS) has been recently emphasized. In a large group of Polish patients we have tested the hypothesis that polymorphism in ApoE and MPO genes may influence the course of the disease. G enotypes were determined in 117 MS patients (74 females and 43 males; 99 sporadic and 18 familial cases) with mean EDSS of 3.6, mean age of 44.1 years, mean duration of the disease 12.8 years and mean onset of MS at 31.2 years, and in 100 healthy controls. The relationship between ApoE and MPO genes’ polymorphism and the MS activity as well as the defect of remyelination (diffuse demyelination) and brain atrophy on MRI were analysed. The ApoE o4 allele was not related to the disease course or the ApoE o2 to the intensity of demyelination on MRI. The genotype MPO G/G was found in all familial MS and in 57% (56/99) of sporadic cases. This genotype was also related to more pronounced brain atrophy on MRI. The MPO G/G subpopulation was characterized by a significantly higher proportion of patients with secondary progressive MS (PB- 0.05) and by a higher value of EDSS. A ccording to our results the MPO G allele is frequently found (in 96% of cases) among Polish patients with MS. More severe nervous tissue damage in the MPO G/G form can be explained by the mechanism of accelerated oxidative stress. It seems that MPO G/G genotype may be one of the genetic factors influencing the progression rate of disability in MS patients.

Cognitive impairment in patients with multiple sclerosis: association with the APOE gene and promoter polymorphisms

Background Studies examining the ε4 allele of the APOE gene as a factor affecting the severity of multiple sclerosis (MS) have yielded conflicting results. The focus of these studies on physical disability to the neglect of cognitive impairment is surprising in light of the associations between the ε4 allele and other dementia conditions. Only two studies examine the relationship between the ε4 allele and cognitive impairment.

Methods A neuropsychological test battery was administered to 263 MS patients, and their current disability status was evaluated. Genotypes were determined for APOE epsilon and for two promoter region polymorphisms (-219 G/T and -491 A/T).

Results Although effects were generally weak, female patients with the -491 AA genotype had a later age of disease onset, lower disability scores, and somewhat higher scores on the cognitive battery. Male patients with the ε2 allele had lower disability and higher scores on the cognitive battery. The ε4 allele was not related to physical disability, and there was no difference between ε4+and ε4– patients in overall cognitive performance. However, when patients with severe cognitive impairment were identified, a greater proportion (52%) of these patients had the ε4 allele than those in the unimpaired group (27%).

Conclusion An association with the ε4 allele was evident in this study, but only in cases of severe cognitive impairment.

Toward biomarkers in multiple sclerosis: new advances

Multiple sclerosis is an autoimmune disease that commonly affects young adults. If initially characterized by acute relapses, it is later followed by only incomplete remission. Over years, progressive disability and irreversible deficit lead to chronic neurological deficits in the majority of patients. The clinical course is protracted and unpredictable, and no biological marker is useful in predicting the evolution of autoaggression and disability. It is difficult to diagnose and to monitor disease progression after the initial symptoms or even during the major clinical manifestations, and it is difficult to treat. In this review, the authors report recent advances in the field, focusing on the search of new antigens as a marker of the disease, in their relevance to the pathophysiology and diagnosis of the disease.

Apolipoprotein E Mimetic Promotes Functional and Histological Recovery in Lysolecithin-Induced Spinal Cord Demyelination in Mice

Objective

Considering demyelination is the pathological hallmark of multiple sclerosis (MS), reducing demyelination and/or promoting remyelination is a practical therapeutic strategy to improve functional recovery for MS. An apolipoprotein E (apoE)-mimetic peptide COG112 has previously demonstrated therapeutic efficacy on functional and histological recovery in a mouse experimental autoimmune encephalomyelitis (EAE) model of human MS. In the current study, we further investigated whether COG112 promotes remyelination and improves functional recovery in lysolecithin induced focal demyelination in the white matter of spinal cord in mice.

Methods

A focal demyelination model was created by stereotaxically injecting lysolecithin into the bilateral ventrolateral funiculus (VLF) of T8 and T9 mouse spinal cords. Immediately after lysolecithin injection mice were treated with COG112, prefix peptide control or vehicle control for 21 days. The locomotor function of the mice was measured by the beam walking test and Basso Mouse Scale (BMS) assessment. The nerve transmission of the VLF of mice was assessed in vivo by transcranial magnetic motor evoked potentials (tcMMEPs). The histological changes were also examined by by eriochrome cyanine staining, immunohistochemistry staining and electron microscopy (EM) method.

Results

The area of demyelination in the spinal cord was significantly reduced in the COG112 group. EM examination showed that treatment with COG112 increased the thickness of myelin sheaths and the numbers of surviving axons in the lesion epicenter. Locomotor function was improved in COG112 treated animals when measured by the beam walking test and BMS assessment compared to controls. TcMMEPs also demonstrated the COG112-mediated enhancement of amplitude of evoked responses.

Conclusion

The apoE-mimetic COG112 demonstrates a favorable combination of activities in suppressing inflammatory response, mitigating demyelination and in promoting remyelination and associated functional recovery in animal model of CNS demyelination. These data support that apoE-mimetic strategy may represent a promising therapy for MS and other demyelination disorders.

Demographic, genetic, and environmental factors that modify disease course

As with susceptibility to disease, it is likely that multiple factors interact to influence the phenotype of multiple sclerosis and long-term disease outcomes. Such factors may include genetic factors, socioeconomic status, comorbid diseases, and health behaviors, as well as environmental exposures. An improved understanding of the influence of these factors on disease course may reap several benefits, such as improved prognostication, allowing us to tailor disease management with respect to intensity of disease-modifying therapies and changes in specific health behaviors, in the broad context of coexisting health issues. Such information can facilitate appropriately adjusted comparisons within and between populations. Elucidation of these factors will require careful study of well-characterized populations in which the roles of multiple factors are considered simultaneously.

The immune-modulatory role of apolipoprotein E with emphasis on multiple sclerosis and experimental autoimmune encephalomyelitis

Apolipoprotein E (apoE) is a 34.2 kDa glycoprotein characterized by its wide tissue distribution and multiple functions. The nonlipid-related properties of apoE include modulating inflammation and oxidation, suppressing T cell proliferation, regulating macrophage functions, and facilitating lipid antigen presentation by CD1 molecules to natural killer T (NKT) cells, and so forth. Increasing studies have revealed that APOE ε allele might be associated with multiple sclerosis (MS), although evidence is still not sufficient enough. In this review, we summarized the current progress of the immunomodulatory functions of apoE, with special focus on the association of APOE ε allele with the clinical features of MS and of its animal model experimental autoimmune encephalomyelitis (EAE).

The genetics of clinical outcome in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS), the clinical course of which varies considerably between patients. Genetic complexity and interactions with as yet unknown environmental factors have hindered researchers from fully elucidating the aetiology of the disease. In addition to influencing disease susceptibility, epidemiological evidence suggests that genetic factors may affect phenotypic expression of the disease. Genes that affect clinical outcome may be more effective therapeutic targets than those which determine susceptibility. We present in this review a comprehensive survey of the genes (both MHC- and non-MHC-related) that have been investigated for their role in disease outcome in MS. Recent studies implicating the role of the genotype and epistatic interactions in the MHC in determining outcome are highlighted.

AR, apoE, and cognitive function

Reduced androgen levels in aged men and women might be risk factors for age-related cognitive decline and Alzheimer's disease (AD). Ongoing clinical trials are designed to evaluate the potential benefit of estrogen in women and of testosterone in men. In this review, we discuss the potential beneficial effects of androgens and androgen receptors (ARs) in males and females. In addition, we discuss the hypothesis that AR interacts with apolipoprotein (apoE)4, encoded by epsilon4 and a risk factor for age-related cognitive decline and AD, and the potential consequences of this interaction.

Apolipoprotein E genotype does not associate with disease severity measured by Multiple Sclerosis Severity Score

OBJECTIVES

During the last years, the association between apolipoprotein E (APOE) polymorphism and disease severity in multiple sclerosis (MS) has been studied with conflicting results. As a result of a considerable individual variation in the clinical course of MS, there is no consensus method for measuring progression using single assessments of disability. Recently, Multiple Sclerosis Severity Score (MSSS) method has been proposed for comparing disease progression using single data. We evaluate in our population if there is any correlation between APOE genotype and severity according to MSSS.

METHODS

We studied 82 patients followed up in our Neurology Unit throughout the year 2005, diagnosed with MS, and with disease duration of at least 2 years. We collected data concerning demographic and clinical variables including age of onset, disease duration, Expanded Disability Status Scale (EDSS) score and the total number of relapses. When reached, we determined the latency to EDSS scores of 4.0 and 6.0. We calculated progression index (PI) and relapse rate (RR). We ascertained MSSS for our patients in the global MSSS table.

RESULTS

We found four patients heterozygous for the E2 allele and 16 for the E4 allele. No patient was homozygous for E2 or E4. RR (P = 0.017 with 95% CI: 0.005-0.57) and PI (P = 0.016 with 95% CI: 0.004-0.38) were significantly lower in E4 carriers. MSSS scores were not associated with carriership of E2 or E4.

CONCLUSION

Our results show no effect of the APOE genotype on the severity of MS measured by MSSS, as a recently published meta-analysis has noticed. So, our data do not support a role for APOE in MS severity, in spite of the seeming influence shown using other measures such as PI. MSSS is probably the best method to measure severity with a single measure of disability and should be used more frequently when performing genetic research.

Identification of differentially expressed proteins in experimental autoimmune encephalomyelitis (EAE) by proteomic analysis of the spinal cord

The present study used isobaric tags for relative and absolute quantitation (iTRAQ) to identify novel targets in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. The expression of 41 proteins was significantly altered in the inflamed spinal cord. Twenty of these are implicated in EAE for the first time and many have previously been shown to play a role in antigen processing, inflammation, neuroprotection, or neurodegeneration.

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.

APOE genotypes in African American female multiple sclerosis patients

Multiple sclerosis (MS) is a chronic inflammatory CNS disorder, resulting in progressive neurological dysfunction. The disease has a higher incidence in Caucasian Americans (CA) than African Americans (AA); however, the latter may have a more aggressive disease course. We used cluster analysis to determine whether there is a difference in disease progression between the races and whether the APOE AND APOC1 genotypes influence the disease progression. AA female patients were younger and had a higher progression index and MS severity score than CA female MS patients. AA females who were APOE 4/4, 2/4, or 2/3 and APOC1 AA had a younger age-of-onset, had primarily a relapsing remitting disease course, with a higher progression index and MS severity score, as assessed by cluster analysis. Cluster analysis also indicated that CA female patients were of two groups. One group was younger, had the APOE 3/3 genotype with relapsing remitting less severe disease. The second CA group was older, had the APOE 3/4 or 2/3 genotypes with more of the secondary progressive more severe disease phenotype. Thus, the AA MS female patients who were APOE 4 carriers had an earlier age-of-onset and more severe disease course than CA MS female patients.

The association between apolipoprotein E and multiple sclerosis

The article is a complete literature study that investigates the association between apolipoprotein E (Apo E) and multiple sclerosis (MS). Apo E is an important factor in transport, uptake, and redistribution of cholesterol, which is significant to remodelling and repair of nerve tissue. Apo E is involved in neurodegenerative diseases and the most well known association is between Apo epsilon4 and Alzheimer's disease. Only one study found that homozygosity for Apo epsilon4 does cause an increased risk of developing MS. No results indicate that heterozygosity for Apo epsilon4 causes a greater risk of developing MS. No association between the Apo epsilon4 allele and MS subgroups, age of onset, and gender has been found. The association between Apo epsilon4 and relapse rate is contradictory. Most results confirm the hypothesis about an association between the Apo epsilon4 allele and increased disease progression. Two longitudinal studies found an association between Apo epsilon4 and increased disease progression. Half of the cross-sectional studies found the same association. Four of seven published studies examining the association between Apo epsilon4 and increased disease progression using magnetic resonance imaging (MRI) found a significant association. Apo epsilon4 appears to be a predisposing factor to a faster disease progression in MS.

Estradiol regulation of astroglia and apolipoprotein E: an important role in neuronal regeneration

The effects of ovarian hormone on neuronal growth and function are well known. However, equally important, but often neglected, are ovarian hormone effects on glia. Our in vivo and in vitro studies show that estradiol modifies both neuronal growth and glial activity and these effects are tightly linked. Estradiol stimulates neurite growth and the release of the glial apolipoprotein E (apoE) in culture studies. Estradiol-stimulated neurite growth in these cultures requires apoE. Estradiol replacement in ovariectomized mice transiently increases the expression of apoE, the low density lipoprotein receptor related protein (LRP) and synaptophysin throughout the brain. Continuous estradiol replacement over two months loses effect on apoE, LRP, and synaptophysin and suppresses reactive gliosis. Estrous cycle variation of glial activation (GFAP) and apoE are not identical. We propose that estradiol (and other ovarian hormones) functions as a zeitgeber to co-ordinate neuronal-glial interactions. Co-ordination assures temporally appropriate excitatory and inhibitory interactions between glia and neurons. With aging and the loss of ovarian cyclicity, some of this co-ordination must be diminished. These observations present significant clinical implications. Approaches to hormone therapy (HT), for diminishing the risk of chronic neurological diseases, need to consider the temporal nature of ovarian hormones in brain repair and plasticity. Moreover, approaches must consider apoE genotype. The neuroprotective effects of HT in numerous chronic age-related diseases may represent effective co-ordination of repair processes rather than direct disease-specific actions. Moreover, the role of glial-derived proteins in neuroprotection should not be ignored.

Allelic association of sequence variants in the herpes virus entry mediator-B gene (PVRL2) with the severity of multiple sclerosis

Discrepant findings have been reported regarding an association of the apolipoprotein E (APOE) gene with the clinical course of multiple sclerosis (MS). To resolve these discrepancies, we examined common sequence variation in six candidate genes residing in a 380-kb genomic region surrounding and including the APOE locus for an association with MS severity. We genotyped at least three polymorphisms in each of six candidate genes in 1,540 Caucasian MS families (729 single-case and multiple-case families from the United States, 811 single-case families from the UK). By applying the quantitative transmission/disequilibrium test to a recently proposed MS severity score, the only statistically significant (P=0.003) association with MS severity was found for an intronic variant in the Herpes Virus Entry Mediator-B Gene PVRL2. Additional genotyping extended the association to a 16.6 kb block spanning intron 1 to intron 2 of the gene. Sequencing of PVRL2 failed to identify variants with an obvious functional role. In conclusion, the analysis of a very large data set suggests that genetic polymorphisms in PVRL2 may influence MS severity and supports the possibility that viral factors may contribute to the clinical course of MS, consistent with previous reports.

The impact of our genes: consequences of the apolipoprotein E polymorphism in Alzheimer disease and multiple sclerosis

Epidemiological studies provide strong evidence that susceptibility to multiple sclerosis (MS) is in part genetically determined. Likewise the heterogeneity in clinical manifestations, temporal course, severity, and in the pathological processes of MS are probably also influenced by our genes. Apolipoprotein E (apoE) polymorphism has been considered a candidate for impacting on MS because of its numerous functions related to brain tissue and evidence for an association with a variety of cerebral disorders, specifically Alzheimer's disease (AD). The apoE alleles epsilon2, epsilon3, and epsilon4 are known to impact differently on aspects such as neuronal growth and repair, neuroprotection and inflammation. After a review of the strong association of the apoE polymorphism with AD, we review the results on MS. These are far less homogenous but have gained support from morphologic and metabolic measures obtained with magnetic resonance imaging indicating a greater extent of brain destruction with the apoE epsilon4 allele. Evidence for a protective role of the epsilon2 allele in MS is weak. In view of the association with AD it is tempting to speculate that neuropsychologic functioning in MS might be even more strongly related to the apoE polymorphism and especially to the epsilon4 allele than other deficits, but few data on this issue are yet available. While part of the association of the apoE polymorphism with AD is supposed to be caused by apoE-isoform dependent effects on amyloid-beta deposition, no single pathogenetically relevant mechanism has yet been confirmed for MS. In summary we presently may assume only subtle effects of the apoE polymorphism on the course of MS. These effects are probably further modulated by other genes and need further investigation.

No association of apolipoprotein E epsilon4 genotype with faster progression or less recovery of relapses in a Spanish cohort of multiple sclerosis

BACKGROUND

Recent data have suggested a faster deterioration of multiple sclerosis (MS) patients who harbour the epsilon4 allele of the apolipoprotein E (APOE) gene. We investigate the relationship of APOE genotypes with disease severity and clinical recovery of relapses in a MS population of the north of Spain.

METHODS

One hundred and thirty-three patients with clinically defined MS were studied. Disease course (relapsing versus progressive), age of onset, duration of the disease and disability measured by the Expanded Disability Status Scale (EDSS) were recorded. Worsening was measured by the Progression Index (PI) and by EDSS 4 and 6 latencies. In 79 patients with relapsing-remitting (RR) MS the degree of clinical recovery of relapses (total versus partial) was assessed.

RESULTS

The frequency of the APOE epsilon4 allele in our patients was similar to that found in other southern European populations. APOE epsilon4 patients did not have a faster progression as assessed by PI and EDSS 4 and 6 latencies. Among 79 patients with RRMS there were no significant differences in the degree of recovery of relapses.

CONCLUSIONS

In this MS population, APOE epsilon4 polymorphism is not associated with a more severe clinical course and does not appear to influence recovery of exacerbations.

Multiple sclerosis genetics: leaving no stone unturned

Compelling epidemiologic and molecular data indicate that genes play a primary role in determining who is at risk for developing multiple sclerosis (MS), how the disease progresses, and how someone responds to therapy. The genetic component of MS etiology is believed to result from the action of allelic variants in several genes. Their incomplete penetrance and moderate individual effect probably reflects epistatic interactions, post-transcriptional regulatory mechanisms, and significant environmental influences. Equally significant, it is also likely that locus heterogeneity exists, whereby specific genes influence susceptibility and pathogenesis in some individuals but not in others. With the aid of novel analytical algorithms, the combined study of genomic, transcriptional, proteomic, and phenotypic information in well-controlled study groups will define a useful conceptual model of pathogenesis and a framework for understanding the mechanisms of action of existing therapies for this disorder, as well as the rationale for novel curative strategies.

Apo E in multiple sclerosis and optic neuritis: the apo E-epsilon4 allele is associated with progression of multiple sclerosis

OBJECTIVE

To investigate the association between apolipoprotein E (Apo E) genotype in multiple sclerosis (MS) and acute monosymptomatic optic neuritis (ON) in a genetically homogeneous population with a high frequency of the Apo epsilon4 allele.

BACKGROUND

The association between heterozygosity of Apo epsilon4 and the development of MS is thoroughly investigated, while the association between homozygosity of Apo epsilon4 and the development of MS is insufficiently studied. The association between Apo E genotype and disease progression remains controversial.

METHODS

475 patients were included, 385 with MS and 90 with ON, consecutively seen in the MS clinic in the County of Copenhagen. Clinical data were obtained from medical records and degree of disability was determined prospectively using the Kurtzke expanded disability status scale (EDSS). Blood samples were used for Apo E genotyping. Disease progression was evaluated by the progression index (PI = EDSS/disease duration). Apo E genotype distribution was compared with 361 healthy controls.

RESULTS

The Apo epsilon genotype distribution in the MS and ON groups was similar to the controls. The rate of disease progression in the group of MS patients with a disease duration of 10 years or less was significantly faster in the Apo epsilon4 positive group (heterozygosity and homozygosity for Apo epsilon4) (PI = 1.41) compared to the Apo epsilon4 negative group (PI =0.92) (P =0.009). Observing the MS subgroups, we found that the group of patients with RRMS had a faster rate of disease progression in the Apo epsilon4 positive group (PI =1.12) compared to the Apo epsilon4 negative group (P =0.77) (P =0.024).

CONCLUSIONS

Apo E genotypes do not influence the development of MS and ON. The Apo epsilon4 allele seems to predispose carriers with MS to a faster progression of disease.

Delayed olfactory nerve regeneration in ApoE-deficient mice

Apolipoprotein E (apoE), a lipid transporting protein, is extensively expressed in the primary olfactory pathway, but its function is unknown. We previously reported increased apoE levels in the olfactory bulb (OB) following olfactory epithelium (OE) lesion in mice, and hypothesized that apoE may play a vital role in olfactory nerve (ON) regeneration. To directly test this hypothesis, we examined the rate of ON regeneration following OE lesion in apoE deficient/knockout (KO) and wild-type (WT) mice. OE was lesioned in 2- to 3-month-old mice by intranasal irrigation with Triton X-100 (TX). OB were collected at 0, 3, 7, 21, 42, and 56 days post-lesion. OB recovery was measured by both immunoblotting and immunohistochemical analysis of growth cone associated protein (GAP) 43 and olfactory marker protein (OMP). The results revealed that (1) OMP recovery in the OB was significantly slower in apoE KO compared to WT mice; (2) recovery of glomerular area was similarly slower; and (3) GAP43 increases and return to prelesion levels in the OB were slower in KO mice. Together, these results show that olfactory nerve regeneration is significantly slower in KO mice as compared to WT mice, suggesting apoE facilitates olfactory nerve regeneration.

Serum uric acid, dehydroepiandrosterone sulphate, and apolipoprotein E genotype in benign vs. progressive multiple sclerosis

The majority of patients with multiple sclerosis (MS) experience gradual progression of disability, either as secondary progressive MS (SPMS) or primary progressive MS (PPMS). A subgroup with relapsing-remitting MS shows a benign course with little or no disease progression and minimal disability decades after the first manifestations, so called benign MS (BMS). In our search to identify factors that are associated with progression of MS, we investigated serum levels of uric acid and dehydroepiandrostenedione sulphate (DHEAS), and apolipoprotein (apo)E genotype in 28 patients with BMS, 33 with SPMS, 21 with PPMS, and 29 healthy individuals. We found no significant changes in uric acid levels and apoE genotype between the four groups. Mean DHEAS levels were lower in MS patients compared with healthy controls (P = 0.049), but there were no significant differences between the clinical subgroups of MS. In patients with SPMS and PPMS there was no correlation between progression rate and serum levels of either uric acid or DHEAS. Our results suggest that serum levels of uric acid and DHEAS, and apoE genotype do not differ between patients with a benign and progressive course of MS.

No major association of ApoE genotype with disease characteristics and MRI findings in multiple sclerosis

BACKGROUND

Whereas a number of studies suggest that the ApoE polymorphism is not associated with disease susceptibility in multiple sclerosis (MS), results with regard to disease severity, however, are conflicting. Some studies suggest an unfavourable role of the epsilon4 allele. This study was performed to assess the association of the ApoE polymorphism with both disease susceptibility and disease course in a large group of MS patients using clinical and MRI measures. In addition the data were combined with available data from the literature.

METHODS

In a group of 408 patients with clinically definite MS, genotype distribution was compared with that of 144 healthy controls. Combined analysis of published data on the association of ApoE polymorphism with MS was performed. Demographic and clinical findings were recorded and related to the ApoE genotype. In a subgroup, longitudinal MRI findings were available and related to the ApoE genotype.

RESULTS

No significant differences were found in the distribution of genotypes between MS patients and controls. Combined analysis of published data showed a slightly increased susceptibility for MS in epsilon2-carriers. Disease characteristics (including age at onset and onset type), disease severity (progression index, time to reach EDSS 6) and MRI findings (lesion volumes and atrophy measures) were not associated with carriership o epsilon2 or epsilon4.

CONCLUSIONS

In this cohort no association of the ApoE genotype with disease susceptibility nor clinical and MRI measures could be identified. However, combined analysis of published data could not definitely exclude the possibility of a minor role for epsilon2-carriership in MS.

Estrogen facilitates neurite extension via apolipoprotein E in cultured adult mouse cortical neurons

Literature review suggests a close relationship between estrogen and apolipoprotein E (ApoE) in the central nervous system. Epidemiology studies show that estrogen replacement therapy (ERT) decreases the morbidity from several chronic neurological diseases. Alleles of ApoE modify the risk for and progression of the same diseases. ApoE levels in the rodent brain vary during the estrous cycle and increase after 17beta-estradiol administration. Both estradiol and ApoE3, the most common isoform of human ApoE, increase the extent of neurite outgrowth in culture. Combined, these observations suggest a common mechanism whereby estrogen may increase ApoE levels to facilitate neurite growth. We tested this hypothesis by characterizing the effects of estradiol and ApoE isoforms on neurite outgrowth in cultured adult mouse cortical neurons. Estradiol increased ApoE levels and neurite outgrowth. ApoE2 increased neurite length more so than ApoE3 in the presence of estradiol. Estradiol had no effect on neurite outgrowth from mice lacking the ApoE gene or when only ApoE4, the isoform of ApoE that is associated with increased risk of neurological disease, was exogenously supplied. Cultures from mice transgenic for human ApoE3 or ApoE4 showed the same isoform-specific effect. Neuronal internalization of recombinant human ApoE3 was greater than ApoE4, and ApoE3 was more effective than ApoE4 in facilitating neuronal uptake of a fatty acid. We conclude that estradiol facilitates neurite growth through an ApoE-dependent mechanism. The effects of ERT on chronic neurological diseases may vary with ApoE genotype. The clinical use of ERT may require ApoE genotyping for optimal efficacy.

Androgens, ApoE, and Alzheimer's Disease

Increasing evidence indicates that there are reductions in estrogen and androgen levels in aged men and women. These hormonal reductions might be risk factors for cognitive impairments and the development of Alzheimer's disease (AD). Aged people show improved cognition after treatments with sex steroids. Therefore, ongoing clinical AD trials have been designed to evaluate the potential benefits of estrogen therapy in women and testosterone therapy in men. Apolipoprotein E (apoE) plays an important role in the metabolism and redistribution of lipoproteins and cholesterol. The three major human apoE isoforms, apoE2, apoE3, and apoE4, differ in their effects on AD risk and pathology. Here I review various mechanisms proposed to mediate the differential effects of apoE isoforms on brain function and highlight the potential contribution of detrimental isoform-dependent effects of apoE on androgen- and androgen receptor (AR)-mediated pathways. I also discuss potential interactions of androgens with other AD-related factors.

Accelerated evolution of brain atrophy and ?black holes? in MS patients withAPOE-?4

Apolipoprotein E (APOE)-epsilon4 has been associated with an unfavorable course of multiple sclerosis (MS). The mechanisms responsible for this are unclear, although cross-sectional MRI demonstrated a higher extent of "black holes" (BHs) in such patients. Here, we have studied the impact of the APOE genotype on both the longitudinal evolution of focal (BH ratio) and global (brain volume change [BVC]) brain tissue damage. Ninety-nine MS patients underwent ApoE genotyping, clinical examination, and magnetic resonance imaging at baseline and after 2.7 +/- 1.1 years to assess lesion load (LL) and BVC. In APOE-epsilon4 patients, the annual reduction in brain volume was fivefold higher (-0.65 +/- 0.61%) than in those without APOE-epsilon4 (-0.13 +/- 0.36%; p = 0.0001). At baseline, T(2) LL and T(1) LL were non-significantly higher in epsilon4 carriers, despite a shorter disease duration and absence of significant clinical differences. During follow-up, T(1) LL increased from 1.2 +/- 2.3 ccm to 1.7 +/- 2.7 ccm in the epsilon4 group, although T(2) LL did not change, leading to a significantly higher increase in the BH ratio [(T(1) LL/T(2) LL) x 100] from 5.5 to 12.4% (p = 0.005). BH ratio remained almost constant in non-epsilon4 patients (5.0 vs 5.7%). Accelerated brain tissue loss and a higher proportion of lesions evolving into BH therefore provide magnetic resonance imaging evidence for more pronounced tissue destruction in MS patients with APOE-epsilon4.

Apolipoprotein E and the Risk of Breast Cancer in African-American and Non-Hispanic White Women

The apolipoprotein genetic polymorphism (APO E) is part of a broader paradigm, highlighting the role of gene-environment interactions as risk factors for human diseases such as cardiovascular disease, Alzheimer’s disease, dementia, atherosclerosis, multiple sclerosis, peripheral artery disease, diabetes, stroke, and most recently, cancer. APO E, a normal constituent of very-low-density lipoproteins and high-density lipoproteins, is involved in many functions, including lipid metabolism, cholesterol transport, tissue repair, immune response and regulation, as well as cell growth and differentiation. The location, frequency and functional effects of this gene have been reviewed elsewhere in terms of cardiovascular disease, Alzheimer’s disease, neuromuscular disease, multiple sclerosis, stroke and diabetes. However, while the majority of studies have examined the significance of APO E as a molecular marker for a variety of diseases in multiethnic populations, few evaluate its role as a putative marker of cancer susceptibility. Fewer explore the importance of APO E on the risk of breast cancer, although some report an association. None have been designed to study its relevance as a marker of breast cancer risk in multiethnic populations. The purpose of this review was to evaluate the association between APO E and the risk for breast cancer in non-Hispanic white and African-American women.

Polymorphisms of apolipoprotein E and Japanese patients with multiple sclerosis

The relation between apolipoprotein (APOE) gene polymorphisms and disease progression of multiple sclerosis (MS) is controversial. The present study was designed to investigate the relation between APOE gene polymorphisms and Japanese patients with MS. We analysed the frequencies of APOE gene polymorphisms in 135 MS patients and 134 healthy controls, using PCR-RFLP. The results showed no significant differences in the distribution of APOE gene polymorphisms between MS patients and controls. With regard to disease progression, there was no association between APOE gene polymorphisms and epsilon4 allele positivity and disease progression index (EDSS/ years). Furthermore, in patients with more than 10 years of disease onset, there were no significant differences between the frequencies of epsilon4 allele and patients with EDSS of more than 6. Although the low rate of epsilon4 allele in Japan should be taken into consideration, our results showed no relation between APOE gene polymorphisms and Japanese patients with MS.

Amyloidogenesis: historical and modern observations point to heparan sulfate proteoglycans as a major culprit

Amyloids are complex tissue deposits and each type is identified by one of 22 different proteins or peptides which become re-folded into non-native conformational intermediates and then assemble into fibrils of a highly regular structure. All amyloid deposits also contain apolipoprotein E (apoE) as well as the basement membrane (BM) components, serum amyloid P and heparan sulfate proteoglycans (HSPG), perlecan or agrin. These BM components likely contribute to the overall organization of amyloid fibrils and HSPG has been further implicated in the genesis of amyloid. A growing body of evidence, summarized in this review, suggests that heparan sulfate (HS) promotes fibrillogenesis by associating with the amyloid precursors and inducing the conformational change required for their assembly into fibrils. HS also remains associated with the nascent fibrils contributing to its stability. These activities of HS are likely mediated through specific binding sites on the precursor proteins which appear to have sequence characteristics that are unique to amyloid.

Infectious agents and multiple sclerosis--are Chlamydia pneumoniae and human herpes virus 6 involved?

A good deal of evidence suggests an infectious component in the development of multiple sclerosis (MS) and, to date, some 20 bacteria and viruses have been associated with the disease. Recent independent sets of studies have implicated the respiratory bacterium Chlamydia pneumoniae and human herpes virus 6 (HHV-6) in the pathogenesis of MS. However, as is the case for essentially all earlier microbial associations, experimental evidence linking either this bacterium or this virus to MS is equivocal. We review the published reports concerning involvement of C. pneumoniae and HHV-6 in MS, and data relating to possession of the APOE epsilon 4 allele, which some studies indicate might influence how these or other pathogens affect disease genesis. Based on the large set of inconsistent observations available and given important new information regarding the neuropathology of MS, we contend that no conclusion is possible at this point regarding the potential role of either C. pneumoniae or HHV-6 in MS. We therefore propose future studies that should clarify whether, and if so how, these and other organisms function in the pathogenesis of this disease.

Inflammation in multiple sclerosis: the good, the bad, and the complex

Inflammation has always been thought of as detrimental in the pathophysiology of multiple sclerosis (MS). However, emerging genetic data, magnetic-resonance-imaging studies, and immunopathological evidence challenge this simplistic view. The evidence leads to the conclusion that inflammation is tightly regulated, and that its net effect may be beneficial in MS, thus explaining some of the results from recent trials of anti-inflammatory agents. We argue that the use of anti-inflammatory drugs to treat MS may not be appropriate in all cases. Precise identification of the inflammatory pathways to be targeted in the different phases of the disease and the timing of such interventions are therefore crucial.