Association of smoking with risk of multiple sclerosis: a population-based study

Smoking during pregnancy and risk of multiple sclerosis in offspring and mother: A Danish nationwide register-based cohort study

BACKGROUND

The association between intra-uterine exposure to maternal smoking and risk of multiple sclerosis (MS) has been little studied and with conflicting results.

OBJECTIVE

To examine the risk of MS in offspring exposed intra-uterine to maternal smoking. In addition, to re-examine prior observations of an elevated risk of MS among smokers, assuming that self-reported smoking during pregnancy reflects the woman's general smoking habits.

METHODS

The study cohort included all Danish women, pregnant in the period 1991-2018, (n = 789,299) and singletons from these pregnancies (n = 879,135). Nationwide information on maternal smoking during pregnancy and MS cases in the study cohort were obtained from the Medical Birth Register and the National Patient Register. Cox regression analysis was used to estimate hazard ratios (HRs) for the association between smoking and MS risk.

RESULTS

Women who smoked during pregnancy had a 42% increased risk of developing MS compared with non-smoking women (HR = 1.42 (1.32-1.52), n = 1,296). The risk of MS among singletons of women who smoked during pregnancy was 38% higher than that among singletons born to non-smoking women (HR = 1.38 (1.08-1.76), n = 110).

CONCLUSION

Our observations add further to the evidence implicating smoking in the development of MS and suggest that intra-uterine exposure to tobacco smoke may increase MS risk.

Multiple sclerosis incidence temporal trend in the Northeast of Iran: Using the Empirical Bayesian method

BACKGROUND

In recent years dramatic changes in multiple sclerosis (MS) incidence have been reported in different provinces in Iran. This study was conducted to assess MS incidence temporal trends from March 21, 2005, to March 20, 2020, and provide a forecast until the end of 2025 in Shahroud county.

METHODS

This longitudinal study was carried out based on the data obtained from the MS registration system in Shahroud county. First, the annual incidence rates were calculated based on the year of diagnosis and smoothed using the Empirical Bayesian Method. Then temporal trends and annual percent change (APC) of MS incidence were analyzed using Joinpoint (JP) regression. Finally, the univariate time series model analysis was used to estimate the MS incidence trend until the end of 2025.

RESULTS

A total of 234 newly diagnosed cases (60 [25.64%] males and 174 [74.36.4%] females) were examined in this study. The mean age of patients at the time of diagnosis was 31.40 ± 3.78. It was 32.01 ± 6.35 and 30.66 ± 4.27 years for males and females, respectively (P<0.22). The mean annual MS incidence was 5.99 ± 1.46, 3.03 ± 0.21, and 8.98 ± 2.79 per 100,000 in overall, males and females respectively. The MS incidence increased significantly from 5.67 (95% CI: 3.63-7.99) in 2005 to 7.58 (95% CI: 5.17-10.28) in 2020 with an APC of 4.5 (2.8 - 6.1). The MS incidence had a non-linear time trend in the study period and the best time trend fitted to the annual MS incidence trend was the non-linear quadratic curve. Based on this model, the annual MS incidence is expected to increase until the end of 2025.

CONCLUSION

Shahroud county is one of the high-risk areas for MS and the increasing trend of MS incidence in it is similar to regional and global changes. This study, also, showed that MS incidence in Shahroud county will be increasing in the coming years.

Apparent changes in the epidemiology and severity of multiple sclerosis

Multiple sclerosis (MS) is an immunological disease that causes acute inflammatory lesions and chronic inflammation in the CNS, leading to tissue damage and disability. As awareness of MS has increased and options for therapy have come into use, a large amount of epidemiological data have been collected, enabling studies of changes in incidence and disease course over time. Overall, these data seem to indicate that the incidence of MS has increased, but the course of the disease has become milder, particularly in the 25 years since the first disease-modifying therapies (DMTs) became available. A clear understanding of these trends and the reasons for them is important for understanding the factors that influence the development and progression of MS, and for clinical management with respect to prevention and treatment decisions. In this Review, we consider the evidence for changes in the epidemiology of MS, focusing on trends in the incidence of the disease over time and trends in the disease severity. In addition, we discuss the factors influencing these trends, including refinement of diagnostic criteria and improvements in health-care systems that have increased diagnosis in people with mild disease, and the introduction and improvement of DMT.

Digesting science: Developing educational activities about multiple sclerosis, prevention and treatment to increase the confidence of affected families

BACKGROUND

The majority of information sources for children of people with multiple sclerosis (MS) are paper, or text, based and require high levels of literacy.

OBJECTIVE

To develop educational activities to inform children who have a parent with MS about a number of aspects around MS and to improve the confidence levels of both parents and children to discuss MS.

METHODS

A structured interactive event, Digesting Science (DS), was developed. This covers the effect MS can have on: vision, bladder function, walking, the mechanisms of action of disease-modifying treatments, the potential importance of vitamin D supplementation, and risk factors for developing MS. Qualitative and semi-quantitative feedback and other data were collected from event questionnaires and a follow-up online survey.

RESULTS

In total, 86 DS events have been delivered internationally, reaching approximately 345 families affected by MS. Confidence ratings around discussing MS improved in 57/77 families (74%; 95% CI: 62.6-83.1) following a DS event. 39/87 (45%) families who attended DS events reported taking vitamin D prior to the event, and 48/87 (55%) were not supplementing. Of those not taking vitamin D supplements, 71% now take vitamin D supplements, 6% have not changed their behaviour, and the remainder were unsure.

CONCLUSION

Educational activities that explain complex neurological diseases to children can be developed and successfully implemented at an international level. These activities give families the confidence to discuss the impact of MS on their lives and also have the potential to change health-related behaviour.

IMPLICATIONS FOR PRACTICE

Creative approaches to health behaviour communication can inform children of parents with MS and may affect their behaviour with the aim of potentially reducing their risk of developing MS in the future. Now more than ever, we need educational resources that can facilitate conversations within families that can respond to health information needs in a timely manner.

Multiple Sclerosis and Smoking

Multiple sclerosis (MS) is a common, severe neurological disease that affects millions of people worldwide. Nevertheless, the actual cause of MS remains unknown. Smoking has been studied with respect to MS development and progression. The objectives of this review were to examine the relationship between smoking and MS and to understand the possible molecular mechanisms underlying the association. PubMed was searched for articles related to the study topic published between 2012 and 2020 using the search terms "multiple sclerosis," "smoking," "risk factors," "cigarettes," and "molecular mechanisms." Studies show a significant relationship between smoking and the risk of MS. Furthermore, smoking has been linked to the progression of MS at the patient and population levels. However, the underlying mechanism remains to be explored in further studies; researchers still disagree on how the relationship between smoking and MS arises in different populations. Evidence from randomized controlled trials, systematic reviews, and epidemiological studies shows that smokers have a higher risk of developing MS and experiencing related adverse symptoms and complications.

Exposure to passive smoking during adolescence is associated with an increased risk of developing multiple sclerosis

BACKGROUND

Environmental factors are associated with acquiring multiple sclerosis (MS) particularly in adolescence.

OBJECTIVE

To test for association between MS and exposure to passive smoking at the age of 10-19.

METHODS

A total of 919 patients from the Danish MS Registry and Biobank and 3419 healthy blood donors who had not smoked before the age of 19 were targeted. We analyzed separately for each sex and for those never-smokers (cohort 1) and active smokers above the age of 19 (cohort 2). All participants completed standardized questionnaires about smoking and lifestyle. We matched cases and controls in the ratio of 1:2 by propensity scores discarding unmatchable individuals and used logistic regression adjusted for all covariates and interactions.

RESULTS

After matching, we included 110/213 male cases/controls and 232/377 female case/controls in cohort 1. In cohort 2, the numbers were 160/320 and 417/760, respectively. Among women in cohort 1, the odds ratio (OR) for MS by passive smoking at the age of 10-19 was 1.432 (p = 0.037) but in men it was 1.232 (p = 0.39). Among men in cohort 2, OR was 1.593 (p = 0.022) but among women it was only 1.102 (p = 0.44).

CONCLUSION

Among never smokers, female MS cases were more often than female controls reported with passive smoking between the age of 10 and 19, and among smokers above the age of 19, male MS patients were more often than male controls reported with passive smoking.

Bacterial transportable toxins of the nasopharyngeal microbiota in multiple sclerosis. Nose-to-brain direct

Intranasal administration delivers molecules directly to the brain bypassing the blood-brain barrier. Three distinct routes of access have been identified; olfactory, trigeminal and via the paranasal sub-mucosa of the posterior sinuses. Consequently, environmental toxins may access the CNS directly to induce inflammatory and degenerative disease. They may also activate bacterial species of the nasal mucosal microbiome to release both immune-deviating cell wall antigens and transportable neurotoxins with local direct access to the CNS. Evidence is reviewed that toxins of the nasal bacterial microbiota may be directly implicated in the inflammatory and degenerative pathogenesis of multiple sclerosis.

Effect of smoking on multiple sclerosis: a meta-analysis

Background

Despite our awareness of the significant effect of smoking on multiple sclerosis (MS), there was a serious lack of information about the effect of different types of smoking habit on MS as well as the dose-response relationship between smoking and MS, but this gap was addressed by this meta-analysis.

Methods

Major electronic databases, including PubMed, Web of Science and Scopus were searched until July 2015. Epidemiological studies addressing the association between smoking and MS were enrolled. The heterogeneity across studies was investigated by Q-test and I2 statistic. The probability of publication bias was explored using Begg's and Egger's tests. The results were expressed as odds ratio (OR) with 95% confidence intervals (CI) using a random effects model.

Results

We identified a total of 10 687 references and included 34 studies involving 623 852 participants. Compared with nonsmokers, the OR estimate of MS was 1.46 (1.33, 1.59) among ever smokers, 1.57 (1.34, 1.80) among current smokers, 1.36 (1.27, 1.46) among ex-smokers and 1.12 (0.87, 1.36) among passive smokers. In addition, analyzing the effect of cigarette pack-year on MS indicated that the OR estimate of MS was 1.34 (1.06, 1.61) for 1-5 cigarette pack-years, 1.56 (1.15, 1.97) for 6-10 cigarette pack-years, 1.74 (1.16, 2.33) for 11-15 cigarette pack-years and 1.46 (0.49, 2.43) for more than 15 cigarette pack-years.

Conclusions

Smoking habits are significantly associated with MS, although the association is not very strong. However, there is a dose-response relationship between the smoking habits and MS.

An 8-year study of people with multiple sclerosis in Isfahan, Iran: Association between environmental air pollutants and severity of disease

The evidence for an impact of ambient air pollution on the incidence and severity of multiple sclerosis (MS) is still limited. In the present study, we assessed the association between daily air pollution levels and MS prevalence and severity in Isfahan city, Iran. Data related to MS patients has been collected from 2008 to 2016 in a referral university clinic. The air quality index (AQI) data, were collected from 6 monitoring stations of Isfahan department of environment. The distribution map presenting the sites of air pollution monitoring stations as well as the residential address of MS patients was plotted on geographical information system (GIS). An increase in AQI level in four areas of the city (north, west, east and south) was associated with higher expanded disability status scale (EDSS) of MS patients[logistic regression odds ratio = 1.01 (95% CI = 1.008,1.012)]. Moreover, significant inverse association between the complete remission after the first attack with AQI level in total areas [logistic regression odds ratio = 0.987 (95% CI = 0.977, 0.997)] was found in crude model. However, after adjustment for confounding variables through multivariate logistic regression, AQI level was associated with degree of complete remission after first attack 1.005 (95% CI = 1.004, 1.006). The results of our study suggest that air pollution could play a role in the severity and remission of MS disease. However, more detailed studies with considering the complex involvement of different environmental factors including sunlight exposure, diet, depression and vitamin D are needed to determine the outcome of MS.

No association of tobacco use and disease activity in multiple sclerosis

Objective:

To study whether tobacco use is associated with MRI and clinical disease activity in patients with multiple sclerosis (MS).

Methods:

Prospective cohort study of 87 patients with relapsing-remitting MS originally included in a randomized placebo-controlled trial of omega-3 fatty acids in MS (the OFAMS Study). Serum levels of cotinine (biomarker of tobacco use) were analyzed at baseline and every 6 months for 2 years. MRI activity was assessed at baseline and monthly for 9 months and after 12 and 24 months.

Results:

Fifty-three patients (61%) had serum cotinine levels ≥85 nmol/L on ≥60% of the measurements and were considered tobacco users and 34 (39%) had cotinine levels <85 nmol/L, consistent with non–tobacco use. There was no association between tobacco use and the occurrence of new gadolinium-enhancing T1 lesions, new or enlarging T2 lesions, or their aggregate (combined unique activity). Furthermore, there was no association between cotinine levels and MRI activity for the tobacco users, and tobacco users did not have more relapses or Expanded Disability Status Scale progression.

Conclusion:

Our results indicate that tobacco use does not directly influence MRI activity or relapse rate in MS. This may implicate that the reported association between smoking and MS disease progression could be mediated through other mechanisms.

The Autoimmune Ecology

Autoimmune diseases (ADs) represent a heterogeneous group of disorders that affect specific target organs or multiple organ systems. These conditions share common immunopathogenic mechanisms (i.e., the autoimmune tautology), which explain the clinical similarities they have among them as well as their familial clustering (i.e., coaggregation). As part of the autoimmune tautology, the influence of environmental exposure on the risk of developing ADs is paramount (i.e., the autoimmune ecology). In fact, environment, more than genetics, shapes immune system. Autoimmune ecology is akin to exposome, that is all the exposures - internal and external - across the lifespan, interacting with hereditary factors (both genetics and epigenetics) to favor or protect against autoimmunity and its outcomes. Herein, we provide an overview of the autoimmune ecology, focusing on the immune response to environmental agents in general, and microbiota, cigarette smoking, alcohol and coffee consumption, socioeconomic status (SES), gender and sex hormones, vitamin D, organic solvents, and vaccines in particular. Inclusion of the autoimmune ecology in disease etiology and health will improve the way personalized medicine is currently conceived and applied.

The risk of smoking on multiple sclerosis: a meta-analysis based on 20,626 cases from case-control and cohort studies

Background. Multiple sclerosis (MS) has become a disease that represents a tremendous burden on patients, families, and societies. The exact etiology of MS is still unclear, but it is believed that a combination of genetic and environmental factors contribute to this disease. Although some meta-analyses on the association between smoking and MS have been previously published, a number of new studies with larger population data have published since then. Consequently, these additional critical articles need to be taken into consideration.

Method. We reviewed articles by searching in PubMed and EMBASE. Both conservative and non-conservative models were used to investigate the association between smoking and the susceptibility to MS. We also explored the effect of smoking on the susceptibility to MS in strata of different genders and smoking habits. The association between passive smoking and MS was also explored.

Results.The results of this study suggest that smoking is a risk factor for MS (conservative model: odds ratio (OR) 1.55, 95% CI [1.48–1.62], p < 0.001; non-conservative model: 1.57, 95% CI [1.50–1.64], p < 0.001). Smoking appears to increase the risk of MS more in men than in women and in current smokers more than in past smokers. People who exposed to passive smoking have higher risk of MS than those unexposed.

Conclusion.This study demonstrated that exposure to smoking is an important risk factor for MS. People will benefit from smoking cessation, and policymakers should pay attention to the association between smoking and MS.

What role does tobacco smoking play in multiple sclerosis disability and mortality? A review of the evidence

There is increasing evidence of tobacco smoking as an associative factor in multiple sclerosis (MS). Numerous studies have been conducted investigating the effects of smoking before the onset of MS as well as its impact on disease course. This special report reviews the available evidence and summarizes the contribution of smoking to increased mortality in patients with MS. It also explores some putative mechanisms for the involvement of tobacco constituents in the pathology of MS and the effects of smoking on disease-modifying treatments.

The Role of Environment and Lifestyle in Determining the Risk of Multiple Sclerosis

MS is a complex disease where both genetic and environmental factors contribute to disease susceptibility. The substantially increased risk of developing MS in relatives of affected individuals gives solid evidence for a genetic base for susceptibility, whereas the modest familial risk, most strikingly demonstrated in the twin studies, is a very strong argument for an important role of lifestyle/environmental factors in determining the risk of MS, sometimes interacting with MS risk genes. Lifestyle factors and environmental exposures are harder to accurately study and quantify than genetic factors. However, it is important to identify these factors since they, as opposed to risk genes, are potentially preventable. We have reviewed the evidence for environmental factors that have been repeatedly shown to influence the risk of MS: Epstein-Barr virus (EBV) infection, ultraviolet radiation (UVR) exposure habits /vitamin D status, and smoking. We have also reviewed a number of additional environmental factors, published in the past 5 years, that have been described to influence MS risk. Independent replication, preferably by a variety of methods, may give still more firm evidence for their involvement.

Tolerance of activated pathogenic CD4+ T cells by transcriptional targeting of dendritic cells

We have recently shown that targeted expression of myelin oligodendrocyte glycoprotein (MOG) to dendritic cells with self-inactivating-lentivirus vectors induces antigen-specific tolerance in naive antigen-specific CD4+ T cells and protects mice from experimental autoimmune encephalomyelitis (EAE). In the present study, we demonstrate that this approach also induces tolerance of activated antigen-specific CD4+ T cells and completely protects mice from passive EAE induction. Tolerance induction did not correlate with the depletion of the preactivated antigen-specific CD4+ T cells. However, upon isolation and in vitro re-stimulation at day 6 after adoptive transfer the MOG-specific CD4+ T cells from the non-tolerized mice produced large amounts of inflammatory cytokines, whereas those from tolerized mice did not. This unresponsiveness correlated with the upregulation of regulatory molecules associated with anergy and regulatory T cells (Tregs). The in vivo depletion of Tregs resulted in EAE susceptibility of the tolerized animals, suggesting that these cells have indeed a role in tolerance induction/maintenance.

Sex-Based Differences in Multiple Sclerosis (MS): Part II: Rising Incidence of Multiple Sclerosis in Women and the Vulnerability of Men to Progression of this Disease

It is well known that a number of autoimmune diseases including multiple sclerosis (MS) predominantly affect women and there has been much attention directed toward understanding why this is the case. Past research has revealed a number of sex differences in autoimmune responses that can account for the female bias in MS. However, much less is known about why the incidence of MS has increased exclusively in women over the past half century. The recency of this increase suggests that changing environmental or lifestyle factors are interacting with biological sex to increase MS risk predominantly in females. Indeed, a number of recent studies have identified sex-specific differences in the effect of environmental factors on MS incidence. The first part of this chapter will overview this evidence and will discuss the possible scenarios of how the environment may be interacting with autoimmune mechanisms to contribute to the preferential rise in MS incidence in women. Despite the strong female bias in MS incidence, culminating evidence from natural history studies, and imaging and pathology studies suggests that males who develop MS may exhibit a more rapid decline in disability and cognitive functioning than women. Very little is known about the biological basis of this more rapid deterioration, but some insights have been provided by studies in rodent models of demyelination/remyelination. The second part of this chapter will overview the evidence that males with relapsing-onset MS undergo a more rapid progression of disease than females and will discuss potential biological mechanisms that account for this sex difference.

HIV and lower risk of multiple sclerosis: beginning to unravel a mystery using a record-linked database study

OBJECTIVES

Even though multiple sclerosis (MS) and HIV infection are well-documented conditions in clinical medicine, there is only a single case report of a patient with MS and HIV treated with HIV antiretroviral therapies. In this report, the patient's MS symptoms resolved completely after starting combination antiretroviral therapy and remain subsided for more than 12 years. Authors hypothesised that because the pathogenesis of MS has been linked to human endogenous retroviruses, antiretroviral therapy for HIV may be coincidentally treating or preventing progression of MS. This led researchers from Denmark to conduct an epidemiological study on the incidence of MS in a newly diagnosed HIV population (5018 HIV cases compared with 50,149 controls followed for 31,875 and 393,871 person-years, respectively). The incidence rate ratio for an HIV patient acquiring MS was low at 0.3 (95% CI 0.04 to 2.20) but did not reach statistical significance possibly due to the relatively small numbers in both groups. Our study was designed to further investigate the possible association between HIV and MS.

METHODS

We conducted a comparative cohort study accessing one of the world's largest linked medical data sets with a cohort of 21,207 HIV-positive patients and 5,298,496 controls stratified by age, sex, year of first hospital admission, region of residence and socioeconomic status and 'followed up' by record linkage.

RESULTS

Overall, the rate ratio of developing MS in people with HIV, relative to those without HIV, was 0.38 (95% CI 0.15 to 0.79).

CONCLUSIONS

HIV infection is associated with a significantly decreased risk of developing MS. Mechanisms of this observed possibly protective association may include immunosuppression induced by chronic HIV infection and antiretroviral medications.

Protective environmental factors for neuromyelitis optica

OBJECTIVE

To determine whether early environmental factors, such as cesarean delivery, breastfeeding, and exposure to smoking or herpes viruses, are associated with neuromyelitis optica (NMO) risk in children.

METHODS

This is a case-control study of pediatric NMO, multiple sclerosis (MS), and healthy subjects. Early-life exposures were obtained by standardized questionnaire. Epstein-Barr virus, cytomegalovirus, and herpes simplex virus 1 antibody responses were determined by ELISA. Multivariate logistic regression models were used to adjust for age at sampling, sex, race, and ethnicity.

RESULTS

Early-life exposures were obtained from 36 pediatric subjects with NMO, 491 with MS, and 224 healthy controls. Daycare (odds ratio [OR] 0.33, 95% confidence interval [CI] 0.14, 0.78; p < 0.01) and breastfeeding (OR 0.42, 95% CI 0.18, 0.99; p = 0.05) were associated with lower odds of having NMO compared with healthy subjects. Cesarean delivery tended to be associated with 2-fold-higher odds of NMO compared with having MS/clinically isolated syndrome (OR 1.98, 95% CI 0.88, 4.59; p = 0.12) or with being healthy (OR 1.95, 95% CI 0.81, 4.71; p = 0.14). Sera and DNA were available for 31 subjects with NMO, 189 with MS, and 94 healthy controls. Epstein-Barr virus, herpes simplex virus 1, cytomegalovirus exposure, and being HLA-DRB1*15 positive were not associated with odds of having NMO compared with healthy subjects.

CONCLUSIONS

Exposure to other young children may be an early protective factor against the development of NMO, as previously reported for MS, consistent with the hypothesis that infections contribute to disease risk modification. Unlike MS, pediatric NMO does not appear to be associated with exposures to common herpes viruses.

Multiple sclerosis clinical course and cardiovascular disease risk - Swedish cohort study

BACKGROUND AND PURPOSE

Cardiovascular disease (CVD) risk amongst multiple sclerosis (MS) patients appears raised, but few studies have examined CVD risk amongst an unselected MS patient group. MS course may be relevant for CVD risk. Our aim was to assess CVD risk and variation by course in MS patients.

METHODS

The Multiple Sclerosis Register identified 7667 patients who received an MS diagnosis between 1964 and 2005. They were matched by age, period, region and sex with 76 045 members of the general population without MS using Swedish registers. Poisson regression compared the two cohorts to estimate the relative risk for CVD, overall, as well as grouped and individual CVD diagnoses.

RESULTS

MS patients had an increased adjusted relative risk (with 95% confidence intervals; number of MS cohort events) for CVD of 1.31 (1.22-1.41; n = 847), with some variation by course: relapsing-remitting 1.38 (1.17-1.62; n = 168); secondary progressive 1.30 (1.18-1.53; n = 405) and primary progressive 1.15 (0.93-1.41; n = 108). The association for the relapsing-remitting course was not significant after excluding the first year of follow-up. Overall incidence rates per 1000 person-years for CVD are 11.8 (11.06-12.66) for the MS cohort and 8.8 (8.60-9.05) for the non-MS cohort. The most pronounced association was for deep vein thrombosis: relapsing-remitting 2.16 (1.21-3.87; n = 14), secondary progressive 3.41 (2.45-4.75; n = 52) and primary progressive 3.57 (1.95-6.56; n = 15). MS was associated with ischaemic stroke but largely during the first year of follow-up. MS was associated with a decreased relative risk for angina pectoris and atrial fibrillation.

CONCLUSIONS

There is a significantly increased relative risk for CVD in MS, particularly for venous thromboembolic disorders in progressive MS, suggesting immobility as a possible factor. An increased frequency of ischaemic stroke in MS is most probably due to surveillance bias resulting from diagnostic investigations for MS. There is no increased relative risk for ischaemic heart disease in MS and atrial fibrillation appears to be less common than amongst the general population.

Hemoglobin as a source of iron overload in multiple sclerosis: does multiple sclerosis share risk factors with vascular disorders?

Although iron is known to be essential for the normal development and health of the central nervous system, abnormal iron deposits are found in and around multiple sclerosis (MS) lesions that themselves are closely associated with the cerebral vasculature. However, the origin of this excess iron is unknown, and it is not clear whether this is one of the primary causative events in the pathogenesis of MS, or simply another consequence of the long-lasting inflammatory conditions. Here, applying a systems biology approach, we propose an additional way for understanding the neurodegenerative component of the disease caused by chronic subclinical extravasation of hemoglobin, in combination with multiple other factors including, but not limited to, dysfunction of different cellular protective mechanisms against extracellular hemoglobin reactivity and oxidative stress. Moreover, such considerations could also shed light on and explain the higher susceptibility of MS patients to a wide range of cardiovascular disorders.