Organic solvents and MS susceptibility: Interaction with MS risk HLA genes

Acute organic solvent toxic encephalopathy: A case report and literature review

Organic solvents are a class of volatile, lipophilic substances that can easily enter the human body through skin and mucous membrane contact as well as air inhalation, and can lead to toxic encephalopathy (TE), especially after entering the lipid-rich nervous system. The present case reports a patient with acute organic solvent toxic encephalopathy (AOSTE), which may have been caused by occasional ink leakage from Xuzhou (Jiangsu, China). By summarizing the history the patient to exposure to organic solvents, clinical manifestations, radiology findings and relevant laboratory tests, we hypothesize that a history of ink exposure, brain magnetic resonance imaging findings and hippuric acid testing were indispensable factors in the diagnosis of AOSTE. After neurological treatment, the patient experienced notable improvement in symptoms. The present study reports on its clinical features, imaging features, treatment and follow-up, and review relevant literature to summarize its clinical experience, hoping to improve our understanding of AOSTE.

Review of evidence linking exposure to environmental stressors and associated alterations in the dynamics of immunosenescence (ISC) with the global increase in multiple sclerosis (MS)

Historical survey confirms that, over the latter part of the 20th century, autoimmune-based diseases, including multiple sclerosis (MS), have shown a worldwide increase in incidence and prevalence. Analytical population studies have established that the exponential rise in MS is not solely due to improvements in diagnosis and healthcare but relates to an increase in autoimmune risk factors. Harmful environmental exposures, including non-communicable social determinants of health, anthropogens and indigenous or transmissible microbes, constitute a group of causal determinants that have been closely linked with the global rise in MS cases. Exposure to environmental stressors has profound effects on the adaptive arm of the immune system and, in particular, the associated intrinsic process of immune ageing or immunosenescence (ISC). Stressor-related disturbances to the dynamics of ISC include immune cell-linked untimely or premature (p) alterations and an accelerated replicative (ar) change. A recognised immune-associated feature of MS is pISC and current evidence supports the presence of an arISC during the disease. Moreover, collated data illustrates the immune-associated alterations that characterise pISC and arISC are inducible by environmental stressors strongly implicated in causing duplicate changes in adaptive immune cells during MS. The close relationship between exposure to environmental risk factors and the induction of pISC and arISC during MS offers a valid mechanism through which pro-immunosenescent stressors may act and contribute to the recorded increase in the global rate and number of new cases of the disease. Confirmation of alterations to the dynamics of ISC during MS provides a rational and valuable therapeutic target for the use of senolytic drugs to either prevent accumulation and enhance ablation of less efficient untimely senescent adaptive immune cells or decelerate the dysregulated process of replicative proliferation. A range of senotherapeutics are available including kinase and transcriptase inhibitors, rapalogs, flavanols and genetically-engineered T cells and the use of selective treatments to control emerging and unspecified aspects of pISC and arISC are discussed.

Occupational risk factors for multiple sclerosis: a systematic review with meta-analysis

Objective

We decided to conduct the first systematic review with meta-analysis to provide the highest level of up-to-date evidence on the occupational risk factors for Multiple Sclerosis.

Methods

A systematic, comprehensive literature search was performed in four electronic academic databases. We included any case-control study that enrolled working-age subjects and compared the proportion of MS cases with controls who were not exposed to an occupational risk factor. The primary outcome was the occurrence of MS. The quality assessment was performed with the Critical Appraisal Checklist for Case Control Studies, developed, and validated by the Joanna Briggs Institute. All the selection process was also carried out by two independent and previously trained researchers.

Results

Overall, the total sample included 19,004 people with MS and 4,164,162 controls. Agricultural workers (OR = 1.44, 95% CI 1.13-1.83), offshore workers (OR = 3.56, 95% CI 2.74-4.61), and hairdressers (OR = 8.25, 95% CI 1.02-66.52) were associated with a higher probability of being diagnosed with MS. In parallel, workers exposed to toxic fumes from oil wells (OR = 16.80, 95% CI 8.33-33.90), low-frequency magnetic fields (OR = 1.71, 95% CI 1.03-2.72), and pesticides (OR = 3.17, 95% CI = 2.53-3.99) also had an increased likelihood of having MS.

Conclusion

Our study has the potential to influence more assertive public policies. Nevertheless, future studies on how the occupational setting may contribute to the incidence of MS are highly recommended.

Systematic review registration

The protocol was registered in the international prospective register of systematic reviews (PROSPERO- CRD42023443257).

Organic solvents and Multiple Sclerosis: the doubled risk dilemma

BACKGROUND

Compensation for industrial disease in the UK may be obtained in two ways. A State scheme includes a list of accepted associations between occupations and diseases with evidence of a causative association. Epidemiological evidence of a doubled risk in the occupation concerned is usually required. This takes no account of variation of exposures within occupations, excluding many occupations where risk is less than doubled. In such cases, compensation for a perceived industrial illness may be obtained in Civil Courts, where excessive exposures can be considered.

AIMS

To show that in the Civil Courts evidence of excessive exposure may lead to compensation for diseases which are not yet compensable as Industrial Injuries in the UK and to draw attention to the association of multiple sclerosis (MS) with solvent exposure.

METHODS

We report the case of an industrial spray painter, who claimed his MS had been caused by high-level exposure to organic solvents, and our examination of the epidemiological evidence submitted.

RESULTS

The painter received compensation by an out-of-court settlement, despite the overall epidemiological risk in relation to solvent exposure having been shown to be less than doubled. The evidence hinged on individual risk in relation to high exposure, genetic susceptibility and demonstration of a plausible mechanism.

CONCLUSIONS

High organic solvent exposure may lead to the development of MS. Those giving evidence in Court need to be able to discuss the epidemiological and toxicological issues in relation to exposure in the individual case.

Multiple Sclerosis Pathogenesis and Updates in Targeted Therapeutic Approaches

PURPOSE OF REVIEW

In this review, we provide a comprehensive update on current scientific advances and emerging therapeutic approaches in the field of multiple sclerosis.

RECENT FINDINGS

Multiple sclerosis (MS) is a common disorder characterized by inflammation and degeneration within the central nervous system (CNS). MS is the leading cause of non-traumatic disability in the young adult population. Through ongoing research, an improved understanding of the disease underlying mechanisms and contributing factors has been achieved. As a result, therapeutic advancements and interventions have been developed specifically targeting the inflammatory components that influence disease outcome. Recently, a new type of immunomodulatory treatment, known as Bruton tyrosine kinase (BTK) inhibitors, has surfaced as a promising tool to combat disease outcomes. Additionally, there is a renewed interested in Epstein-Barr virus (EBV) as a major potentiator of MS. Current research efforts are focused on addressing the gaps in our understanding of the pathogenesis of MS, particularly with respect to non-inflammatory drivers. Significant and compelling evidence suggests that the pathogenesis of MS is complex and requires a comprehensive, multilevel intervention strategy. This review aims to provide an overview of MS pathophysiology and highlights the most recent advances in disease-modifying therapies and other therapeutic interventions.

Risk factors for multiple sclerosis in the context of Epstein-Barr virus infection

Compelling evidence indicates that Epstein Barr virus (EBV) infection is a prerequisite for multiple sclerosis (MS). The disease may arise from a complex interplay between latent EBV infection, genetic predisposition, and various environmental and lifestyle factors that negatively affect immune control of the infection. Evidence of gene-environment interactions and epigenetic modifications triggered by environmental factors in genetically susceptible individuals supports this view. This review gives a short introduction to EBV and host immunity and discusses evidence indicating EBV as a prerequisite for MS. The role of genetic and environmental risk factors, and their interactions, in MS pathogenesis is reviewed and put in the context of EBV infection. Finally, possible preventive measures are discussed based on the findings presented.

Laser waterless cleaning of residual organic solvents on the surface of polyurethane coatings

Residual organic solvents have a great impact on the physical and mental health of equipment operators in industry and agriculture. Laser waterless cleaning technology of residual organic solvents on the surface of polyurethane coatings has great application prospects and is a good way to tackle the pollution problem. In this paper, the evolutionary behavior of a laser waterless cleaning mechanism and substrate surface state is analyzed. The influence law of laser energy density and scanning speed on the residual solvent cleaning effect was investigated. The optimal laser cleaning parameters were obtained by comprehensive evaluation of the substrate surface cleaning effect and microscopic morphology. The peak of solvent characteristics before and after laser cleaning was detected by Raman spectroscopy. The results demonstrated that the laser cleaning effect was better with the increase of energy density or the decrease of scanning speed in the substrate damage range, and the best laser cleaning parameters were laser energy density of 0.24J/c m 2 and scanning speed of 500 mm/s. A significant reduction of the peak of Raman spectroscopy was found, reflecting the excellent effect of laser waterless cleaning of residual organic solvents.

Deficit of homozygosity among 1.52 million individuals and genetic causes of recessive lethality

Genotypes causing pregnancy loss and perinatal mortality are depleted among living individuals and are therefore difficult to find. To explore genetic causes of recessive lethality, we searched for sequence variants with deficit of homozygosity among 1.52 million individuals from six European populations. In this study, we identified 25 genes harboring protein-altering sequence variants with a strong deficit of homozygosity (10% or less of predicted homozygotes). Sequence variants in 12 of the genes cause Mendelian disease under a recessive mode of inheritance, two under a dominant mode, but variants in the remaining 11 have not been reported to cause disease. Sequence variants with a strong deficit of homozygosity are over-represented among genes essential for growth of human cell lines and genes orthologous to mouse genes known to affect viability. The function of these genes gives insight into the genetics of intrauterine lethality. We also identified 1077 genes with homozygous predicted loss-of-function genotypes not previously described, bringing the total set of genes completely knocked out in humans to 4785.

Association between exposure to combustion-related air pollution and multiple sclerosis risk

BACKGROUND

Smoking and occupational pulmonary irritants contribute to multiple sclerosis (MS) development. We aimed to study the association between ambient air pollution and MS risk and potential interaction with the human leukocyte antigen (HLA)-DRB1*15:01 allele.

METHODS

Exposure to combustion-related air pollution was estimated as outdoor levels of nitrogen oxides (NOx) at the participants' residence locations, by spatially resolved dispersion modelling for the years 1990-18. Using two population-based case-control studies (6635 cases, 8880 controls), NOx levels were associated with MS risk by calculating odds ratios (OR) with 95% confidence intervals (CI) using logistic regression models. Interaction between high NOx levels and the HLA-DRB1*15:01 allele regarding MS risk was calculated by the attributable proportion due to interaction (AP). In addition, a register study was performed comprising all MS cases in Sweden who had received their diagnosis between 1993 and 2018 (n = 22 173), with 10 controls per case randomly selected from the National Population register.

RESULTS

Residential air pollution was associated with MS risk. NOx levels (3-year average) exceeding the 90th percentile (24.6 µg/m3) were associated with an OR of 1.37 (95% CI 1.10-1.76) compared with levels below the 25th percentile (5.9 µg/m3), with a trend of increasing risk of MS with increasing levels of NOx (P <0.0001). A synergistic effect was observed between high NOx levels (exceeding the lower quartile among controls) and the HLA-DRB1*15:01 allele regarding MS risk (AP 0.26, 95% CI 0.13-0.29).

CONCLUSIONS

Our findings indicate that moderate levels of combustion-related ambient air pollution may play a role in MS development.

The Multiple Sclerosis Modulatory Potential of Natural Multi-Targeting Antioxidants

Multiple sclerosis (MS) is a complex neurodegenerative disease. Although its pathogenesis is rather vague in some aspects, it is well known to be an inflammatory process characterized by inflammatory cytokine release and oxidative burden, resulting in demyelination and reduced remyelination and axonal survival together with microglial activation. Antioxidant compounds are gaining interest towards the manipulation of MS, since they offer, in most of the cases, many benefits, due to their pleiotropical activity, that mainly derives from the oxidative stress decrease. This review analyzes research articles, of the last decade, which describe biological in vitro, in vivo and clinical evaluation of various categories of the most therapeutically applied natural antioxidant compounds, and some of their derivatives, with anti-MS activity. It also summarizes some of the main characteristics of MS and the role the reactive oxygen and nitrogen species may have in its progression, as well as their relation with the other mechanistic aspects of the disease, in order for the multi-targeting potential of those antioxidants to be defined and the source of origination of such activity explained. Antioxidant compounds with specific characteristics are expected to affect positively some aspects of the disease, and their potential may render them as effective candidates for neurological impairment reduction in combination with the MS treatment regimen. However, more studies are needed in order such antioxidants to be established as recommended treatment to MS patients.

Medicinal herbs and multiple sclerosis: Overview on the hard balance between new therapeutic strategy and occupational health risk

Multiple sclerosis (MS) is an autoimmune disease characterized by demyelination and axonal loss of the central nervous system (CNS). Despite its spread throughout the world, the mechanisms that determine its onset are still to be defined. Immunological, genetic, viral, and environmental factors and exposure to chemicals may trigger MS. Many studies have highlighted the anti-inflammatory and anti-oxidant effects of medicinal herbs, which make them a natural and complementary treatment for neurodegenerative diseases. A severe reduction of several MS symptoms occurs with herbal therapy. Thus, the request for medicinal plants with potential beneficial effects, for MS patients, is constantly increasing. Consequently, a production increase needs. Unfortunately, many medicinal herbs were untested and their action mechanism, possible adverse effects, contraindications, or interactions with other drugs, are poorly or not investigated. Keeping in mind the pathological mechanisms of MS and the oxidative damages and mitochondrial dysfunctions induced by pesticides, it is important to understand if pesticides used to increase agricultural productivity and their residues in medicinal plants, may increase the risk of developing MS in both workers and consumers. Studies providing some indication about the relationship between environmental exposure to pesticides and MS disease incidence are few, fragmentary, and discordant. The aim of this article is to provide a glance at the therapeutic potential of medicinal plants and at the risk for MS onset of pesticides used by medicinal plant growers and present in medicinal herbs.

The increased risk of multiple sclerosis associated with HLA-DRB1*15:01 and smoking is modified by alcohol consumption

Previous studies have observed an inverse association between alcohol consumption and multiple sclerosis (MS) risk. We aimed to investigate possible interactions between alcohol consumption, MS-associated human leukocyte antigen (HLA) genes and smoking regarding MS risk. We used a Swedish population-based case-control study (2059 incident cases, 2887 controls) matched by age, sex, and residential area. Subjects with different genotypes and alcohol consumption habits were compared regarding MS risk, by calculating odds ratios with 95% confidence intervals using logistic regression models. Interaction on the additive scale between non-drinking and both genotype and smoking were assessed by calculating the attributable proportion due to interaction (AP). There was a dose-dependent inverse association between alcohol consumption and MS risk (p for trend < 0.0001). A potentiating effect was observed between non-drinking and presence of DRB1*15:01 (AP 0.3, 95% CI 0.2-0.5) which was of similar magnitude irrespective of smoking habits. Non-drinking also interacted with smoking to increase MS risk (AP 0.2, 95% CI 0.06-0.4). Non-drinking interacts with DRB1*15:01 and smoking to increase the risk of MS. Better understanding of the mechanisms behind our findings may help to define ways to achieve protection against MS by other means than alcohol consumption.

Genetic, Environmental and Lifestyle Determinants of Accelerated Telomere Attrition as Contributors to Risk and Severity of Multiple Sclerosis

Telomeres are protective structures at the ends of linear chromosomes. Shortened telomere lengths (TL) are an indicator of premature biological aging and have been associated with a wide spectrum of disorders, including multiple sclerosis (MS). MS is a chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system. The exact cause of MS is still unclear. Here, we provide an overview of genetic, environmental and lifestyle factors that have been described to influence TL and to contribute to susceptibility to MS and possibly disease severity. We show that several early-life factors are linked to both reduced TL and higher risk of MS, e.g., adolescent obesity, lack of physical activity, smoking and vitamin D deficiency. This suggests that the mechanisms underlying the disease are connected to cellular aging and senescence promoted by increased inflammation and oxidative stress. Additional prospective research is needed to clearly define the extent to which lifestyle changes can slow down disease progression and prevent accelerated telomere loss in individual patients. It is also important to further elucidate the interactions between shared determinants of TL and MS. In future, cell type-specific studies and advanced TL measurement methods could help to better understand how telomeres may be causally involved in disease processes and to uncover novel opportunities for improved biomarkers and therapeutic interventions in MS.

Role of environmental factors in multiple sclerosis

INTRODUCTION

Environmental factors play a significant role in the pathogenesis and progression of multiple sclerosis (MS), either acting alone or by interacting with other environmental or genetic factors. This cumulative exposure to external risk factors is highly complex and highly variable between individuals.

AREAS COVERED

We narratively review the current evidence on the role of environment-specific risk factors in MS onset and progression, as well as the effect of gene-environment interactions and the timing of exposure We have reviewed the latest literature, by Ovid Medline, retrieving the most recently published systematic reviews and/or meta-analyses and more recent studies not previously included in meta-analyses or systematic reviews.

EXPERT OPINION

There is some good evidence supporting the impact of some environmental risk factors in increasing the risk of developing MS. Tobacco smoking, low vitamin D levels and/or low sun exposure, Epstein Barr Virus (EBV) seropositivity and a history of infectious mononucleosis may increase the risk of developing MS. Additionally, there is some evidence that gene-smoking, gene-EBV, and smoking-EBV interactions additively affect the risk of MS onset. However, the evidence for a role of other environmental factors in MS progression is limited. Finally, there is some evidence that tobacco smoking, insufficient vitamin D levels and/or sun exposure have impacts on MS phenotypes and various markers of disease activity including relapse, disability progression and MRI findings. Clearly the effect of environmental factors on MS disease course is an area that requires significantly more research.

DRB1-environment interactions in multiple sclerosis etiology: results from two Swedish case-control studies

OBJECTIVE

We aimed to investigate the influence of environmental risk factors for multiple sclerosis (MS) in different genetic contexts, and study if interactions between environmental factors and human leucocyte antigen (HLA) genes differ in magnitude according to heterozygocity and homozygocity for HLA-DRB1*15:01.

METHODS

Using population-based case-control studies (6985 cases, 6569 controls), subjects with different genotypes and smoking, EBNA-1 status and adolescent Body Mass status, were compared regarding MS risk, by calculating OR with 95% CI employing logistic regression. The interaction between different genotypes and each environmental factor was evaluated on the additive scale.

RESULTS

The effect of each DRB1*15:01 allele on MS risk was additive on the log-odds scale for each additional allele. Interaction between DRB1*15:01 and each assessed environmental factor was of similar magnitude regardless of the number of DRB1*15:01 alleles, although ORs were affected. When any of the environmental factors were present in DRB1*15:01 carriers without the protective A*02:01 allele, a three-way interaction occurred and rendered high ORs, especially among DRB1*15:01 homozygotes (OR 20.0, 95% CI 13.1 to 30.5 among smokers, OR 21.9, 95% CI 15.0 to 31.8 among those with elevated EBNA-1 antibody levels, and OR 44.3, 95% CI 13.5 to 145 among those who reported adolescent overweight/obesity).

CONCLUSIONS

The strikingly increased MS risk among DRB*15:01 homozygotes exposed to any of the environmental factors is a further argument in favour of these factors acting on immune-related mechanisms. The data further reinforce the importance of preventive measures, in particular for those with a genetic susceptibility to MS.

Gene-Environment Interactions in Multiple Sclerosis: A UK Biobank Study

Objective

We sought to determine whether genetic risk modifies the effect of environmental risk factors for multiple sclerosis (MS). To test this hypothesis, we tested for statistical interaction between polygenic risk scores (PRS) capturing genetic susceptibility to MS and environmental risk factors for MS in UK Biobank.

Methods

People with MS were identified within UK Biobank using ICD-10–coded MS or self-report. Associations between environmental risk factors and MS risk were quantified with a case-control design using multivariable logistic regression. PRS were derived using the clumping-and-thresholding approach with external weights from the largest genome-wide association study of MS. Separate scores were created including major histocompatibility complex (MHC) (PRS_MHC) and excluding (PRS_non-MHC) the MHC locus. The best-performing PRS were identified in 30% of the cohort and validated in the remaining 70%. Interaction between environmental and genetic risk factors was quantified using the attributable proportion due to interaction (AP) and multiplicative interaction.

Results

Data were available for 2,250 people with MS and 486,000 controls. Childhood obesity, earlier age at menarche, and smoking were associated with MS. The optimal PRS were strongly associated with MS in the validation cohort (PRS_MHC: Nagelkerke's pseudo-R² 0.033, p = 3.92 × 10⁻¹¹¹; PRS_non-MHC: Nagelkerke's pseudo-R² 0.013, p = 3.73 × 10⁻⁴³). There was strong evidence of interaction between polygenic risk for MS and childhood obesity (PRS_MHC: AP = 0.17, 95% CI 0.06–0.25, p = 0.004; PRS_non-MHC: AP = 0.17, 95% CI 0.06–0.27, p = 0.006).

Conclusions

This study provides novel evidence for an interaction between childhood obesity and a high burden of autosomal genetic risk. These findings may have significant implications for our understanding of MS biology and inform targeted prevention strategies.

Moving from two- to multi-way interactions among binary risk factors on the additive scale

Many studies have focused on investigating deviations from additive interaction of two dichotomous risk factors on a binary outcome. There is, however, a gap in the literature with respect to interactions on the additive scale of >2 risk factors. In this paper, we present an approach for examining deviations from additive interaction among three or more binary exposures. The relative excess risk due to interaction (RERI) is used as measure of additive interaction. First, we concentrate on three risk factors – we propose to decompose the total RERI to: the RERI owned to the joint presence of all three risk factors and the RERI of any two risk factors, given that the third is absent. We then extend this approach, to >3 binary risk factors. For illustration, we use a sample from data from the Greek EPIC cohort and we investigate the association with overall mortality of Mediterranean diet, body mass index , and smoking. Our formulae enable better interpretability of any evidence for deviations from additivity owned to more than two risk factors and provide simple ways of communicating such results from a public health perspective by attributing any excess relative risk to specific combinations of these factors.

Abbreviations: BMI: Body Mass Index; ERR: excess relative risk; EPIC: European Prospective Investigation into Cancer and nutrition; MD: Mediterranean diet; RERI: relative excess risk due to interaction; RR: relative risk; TotRERI: total relative excess risk due to interaction

Work-related exposure to organic solvents and the risk for multiple sclerosis-a systematic review

Purpose

Multiple sclerosis (MS) is a chronic progressive neurological disorder. Several environmental factors have been discussed as possible causing agents, e.g. organic solvents, whose impact on the disease is analysed in this review.

Methods

Systematic search strategies were used to identify high-quality studies of workers exposed to organic solvents, published up to September 30, 2019, in databases, such as PubMed, Cochrane library and Scopus. The exposure was in most studies obtained by questionnaires, supplemented with telephone interviews. The diagnosis MS was mainly detemined following a thorough neurological examination. Finally, fourteen case–control studies and two cohort studies met the inclusion criteria and were included in the meta-analysis. Random effects models were used to pool the results of the studies.

Results

The odds ratios from the 14 case–control studies included in the meta-analysis ranged from 0.12–4.0. Five case–control studies and one cohort study showed a significant association between the development of multiple sclerosis and exposure to organic solvents. The results from the other nine case–control studies and from one of the two cohort studies did not reach statistical significance. The pooled data from the 14 case–control studies gave an OR of 1.44 (95% CI 1.03–1.99), which shows a moderately increased risk of developing MS after exposure to organic solvents.

Conclusions

The final interpretation of the result is that organic solvents may be slightly associated with an increased risk to develop MS. In addition, other factors, e.g. genetic markers and smoking, may contribute to the development of the disease.

Mechanisms of Environment-Induced Autoimmunity

Although numerous environmental exposures have been suggested as triggers for preclinical autoimmunity, only a few have been confidently linked to autoimmune diseases. For disease-associated exposures, the lung is a common site where chronic exposure results in cellular toxicity, tissue damage, inflammation, and fibrosis. These features are exacerbated by exposures to particulate material, which hampers clearance and degradation, thus facilitating persistent inflammation. Coincident with exposure and resulting pathological processes is the posttranslational modification of self-antigens, which, in concert with the formation of tertiary lymphoid structures containing abundant B cells, is thought to promote the generation of autoantibodies that in some instances demonstrate major histocompatibility complex restriction. Under appropriate gene-environment interactions, these responses can have diagnostic specificity. Greater insight into the molecular and cellular requirements governing this process, especially those that distinguish preclinical autoimmunity from clinical autoimmunedisease, may facilitate determination of the significance of environmental exposures in human autoimmune disease.

Smoking and Epstein-Barr virus infection in multiple sclerosis development

It is unclear whether smoking interacts with different aspects of Epstein-Barr virus (EBV) infection with regard to multiple sclerosis (MS) risk. We aimed to investigate whether smoking acts synergistically with elevated EBNA-1 antibody levels or infectious mononucleosis (IM) history regarding MS risk. Two Swedish population-based case-control studies were used (6,340 cases and 6,219 matched controls). Subjects with different smoking, EBNA-1 and IM status were compared regarding MS risk, by calculating odds ratios (OR) with 95% confidence intervals (CI) employing logistic regression. Potential interaction on the additive scale was evaluated by calculating the attributable proportion due to interaction (AP). Current and past smokers had higher EBNA-1 antibody levels than never smokers (p < 0.0001). There was an additive interaction between current smoking and high EBNA-1 antibody levels (AP 0.3, 95% CI 0.2-0.4), but not between past smoking and high EBNA-1 antibody levels (AP 0.01, 95% CI - 0.1 to 0.1), with regard to MS risk. An interaction also occurred between current smoking and IM history (AP 0.2, 95% CI 0.004-0.4), but not between past smoking and IM history (AP - 0.06, 95% CI - 0.4 to 0.3). Current smoking increases EBNA-1 antibody levels and acts synergistically with both aspects of EBV infection to increase MS risk, indicating that there is at least one pathway to disease in which both risk factors are involved.

Hospital diagnosed pneumonia before age 20 years and multiple sclerosis risk

Introduction

Respiratory inflammation has been proposed as a risk factor for MS. This study aims to determine if hospital-diagnosed pneumonia in adolescence (before age 20 years) is associated with subsequent multiple sclerosis (MS).

Methods

This case-control study included incident MS cases after age 20 years identified using the Swedish national registers. Cases were matched with 10 general population controls by age, sex and region. Pneumonia diagnoses were identified between 0–5, 6–10, 11–15 and 16–20 years of age. Conditional logistic regression models adjusted for infectious mononucleosis (IM) and education calculated ORs with 95% CIs. Urinary tract infections (UTIs), a common complication of MS, before age 20 years were included as a control diagnosis for reverse causation.

Results

There were 6109 cases and 49 479 controls included. Pneumonia diagnosed between age 11–15 years was associated with subsequent MS (adj OR 2.00, 95% CI 1.22 to 3.27). Although not statistically significant, sensitivity analyses showed similar magnitude associations of pneumonia between age 11–15 years and MS. No statistically significant associations with MS for pneumonia at other age groups were observed. Adjustment for IM had no notable effect on associations, but was statistically significantly associated with MS. UTIs were not associated with MS.

Conclusion

Pneumonia at 11–15 years of age was associated with MS, suggesting a possible role for inflammation of the respiratory system in the aetiology of MS during a period of susceptibility in adolescence. Further research on respiratory infections prior to MS onset should be conducted to replicate this finding and determine explanatory causal mechanisms.

The epidemiology of multiple sclerosis in the entre Douro e Vouga region of northern Portugal: a multisource population-based study

BACKGROUND

The prevalence of Multiple Sclerosis (MS) has been increasing worldwide and the north-south gradient of prevalence may be disappearing in the Northern hemisphere. The few previous prevalence studies performed in Portugal have reported a lower prevalence than the average for Western Europe. The aim of this study is to estimate the prevalence of MS in the Entre Douro e Vouga region, in Northern Portugal.

METHODS

Multiple overlapping sources were used to ascertain all cases from the reference population: records from hospitals in the region and neighbouring regions; diagnostic databases of primary care physicians; and applications for disability benefits. The prevalence date was set at 1 January 2014. The reference population was 274,859 inhabitants. Patients' neurologists were contacted to retrieve clinical information and confirm the diagnosis based.

RESULTS

A total of 177 patients were identified after eliminating duplicates from different sources. The female to male ratio was 1.9 and the mean age at disease onset was 33.5 (standard deviation: 10.3). Clinically isolated syndrome accounted for 9.0% of patients, relapsing remitting for 58.8%, secondary progressive for 20.3% and primary progressive for 11.8%. The prevalence was estimated in 64.4 patients per 100,000 (95% confidence interval: 54.9;73.9).

CONCLUSIONS

In this study we report a higher point prevalence of MS than had been previously described in Portugal, but still far from the higher values recently reported in other Southern European countries.

Aberrant DNA methylation profile exacerbates inflammation and neurodegeneration in multiple sclerosis patients

Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system characterised by incoordination, sensory loss, weakness, changes in bladder capacity and bowel function, fatigue and cognitive impairment, creating a significant socioeconomic burden. The pathogenesis of MS involves both genetic susceptibility and exposure to distinct environmental risk factors. The gene x environment interaction is regulated by epigenetic mechanisms. Epigenetics refers to a complex system that modifies gene expression without altering the DNA sequence. The most studied epigenetic mechanism is DNA methylation. This epigenetic mark participates in distinct MS pathophysiological processes, including blood-brain barrier breakdown, inflammatory response, demyelination, remyelination failure and neurodegeneration. In this study, we also accurately summarised a list of environmental factors involved in the MS pathogenesis and its clinical course. A literature search was conducted using MEDLINE through PubMED and Scopus. In conclusion, an exhaustive study of DNA methylation might contribute towards new pharmacological interventions in MS by use of epigenetic drugs.

MS risk in immigrants in the McDonald era: A population-based study in Ontario, Canada

OBJECTIVE

To determine risk factors for multiple sclerosis (MS) in immigrants and to compare MS risk in immigrants and long-term residents in Ontario, Canada.

METHODS

We applied a validated algorithm to linked, population-based immigration and health claims data to identify incident cases of MS in immigrants and long-term residents between 1994 and 2016. We conducted 2 multivariable Cox proportional hazards regression analyses: 1 analysis limited to the immigrant cohort assessing potential risk factors for developing MS, and 1 analysis comparing MS risk between immigrants and matched long-term residents (1:3 match).

RESULTS

We identified 2,304,302 immigrants for the immigrant-only analysis, of whom 1,526 (0.066%) developed MS. Risk was greatest in those <15 years old at landing (referent <15 years; 16-30 years: hazard ratio [HR] 0.73, 95% confidence interval [CI] 0.63-0.85; 31-45 years: HR 0.55, 95% CI 0.47-0.64). Immigrants from the Middle East (HR 1.22, 95% CI 1.06-1.40) were at greater MS risk than immigrants from Western nations; all other regions had lower risk (p < 0.0001). The matched analysis included 2,207,751 immigrants and 6,362,169 long-term residents. Immigrants were less likely to develop MS than long-term residents (p < 0.0001), although this lower risk was attenuated with longer residence in Canada.

CONCLUSIONS

MS incidence in immigrants to Ontario, Canada, varied widely by region of origin, with greatest risk seen in those from the Middle East. Longer residence in Canada was associated with increased risk, even with migration in adulthood, suggesting that environmental exposures into adulthood contribute to MS risk.

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.

Environmental and genetic risk factors for MS: an integrated review

Recent findings have provided a molecular basis for the combined contributions of multifaceted risk factors for the onset of multiple sclerosis (MS). MS appears to start as a chronic dysregulation of immune homeostasis resulting from complex interactions between genetic predispositions, infectious exposures, and factors that lead to pro-inflammatory states, including smoking, obesity, and low sun exposure. This is supported by the discovery of gene-environment (GxE) interactions and epigenetic alterations triggered by environmental exposures in individuals with particular genetic make-ups. It is notable that several of these pro-inflammatory factors have not emerged as strong prognostic indicators. Biological processes at play during the relapsing phase of the disease may result from initial inflammatory-mediated injury, while risk factors for the later phase of MS, which is weighted toward neurodegeneration, are not yet well defined. This integrated review of current evidence guides recommendations for clinical practice and highlights research gaps.

Therapeutic Effect of the Mitochondria-Targeted Antioxidant SkQ1 on the Culture Model of Multiple Sclerosis

Multiple sclerosis (MS) is a heterogeneous autoimmune disease of unknown etiology characterized by inflammation, demyelination, and axonal degeneration that affects both the white and gray matter of CNS. Recent large-scale epidemiological and genomic studies identified several genetic and environmental risk factors for the disease. Among them are environmental factors of infectious origin, possibly causing MS, which include Epstein-Barr virus infection, reactivation of some endogenous retrovirus groups, and infection by pathogenic bacteria (mycobacteria, Chlamydia pneumoniae, and Helicobacter pylori). However, the nature of the events leading to the activation of immune cells in MS is mostly unknown and there is no effective therapy against the disease. Amazingly, whatever the cause of the disease, signs of damage to the nerve tissue with MS lesions were the same as with infectious leprosy, while in the latter case nitrozooxidative stress was suggested as the main cause of the nerve damage. With this in mind and following the hypothesis that excessive production of mitochondrial reactive oxygen species critically contributes to MS pathogenesis, we studied the effect of mitochondria-targeted antioxidant SkQ1 in an in vitro MS model of the primary oligodendrocyte culture of the cerebellum, challenged with lipopolysaccharide (LPS). SkQ1 was found to accumulate in the mitochondria of oligodendrocytes and microglial cells, and it was also found to prevent LPS-induced inhibition of myelin production in oligodendrocytes. The results implicate that mitochondria-targeted antioxidants could be promising candidates as components of a combined therapy for MS and related neurological disorders.

Interplay between alcohol, smoking and HLA genes in RA aetiology

Objectives

The relationship between alcohol consumption and risk for rheumatoid arthritis (RA) is incompletely understood. We aimed to determine the influence of alcohol on anticitrullinated protein antibody (ACPA) positive and ACPA-negative RA and investigate potential interactions between alcohol consumption, smoking and the presence of human leucocyte antigen (HLA)-DRB1-shared epitope (SE).

Methods

A Swedish population-based case–control study with incident cases of RA was used (3353 cases, 2836 matched controls). Subjects with different HLA-DRB1-SE status, smoking and alcohol consumption were compared regarding risk of ACPA-positive and ACPA-negative RA, by calculating OR with 95% CI employing logistic regression. Interaction on the additive scale between alcohol, HLA-DRB1-SE and smoking was estimated by calculating the attributable proportion (AP) due to interaction.

Results

Compared with non-drinking, low and moderate alcohol consumption was dose dependently associated with a reduced risk of ACPA-positive and ACPA-negative RA. Independent of smoking habits, non-drinking and the presence of HLA-DRB1-SE interacted to increase the risk of ACPA-positive RA. Among HLA-DRB1-SE positive subjects, there was also a significant interaction between non-drinking and smoking with regard to risk for ACPA-positive RA. A three-way interaction was observed between alcohol, smoking and HLA-DRB1-SE with regard to risk for ACPA-positive RA (AP 0.7, 95% CI 0.6 to 0.8) that remained significant when the influence from the two-way interactions was removed (AP 0.4, 95% CI 0.2 to 0.6).

Conclusions

Our findings emphasize the need to investigate complex interactions between several environmental and genetic factors in order to better understand the etiology of RA. Whereas of great interest in an aetiological perspective, the finding of a protective role of alcohol on risk for RA must, however, be interpreted with caution in a clinical and public health perspective.

Smoking and its interaction with genetics in MS etiology

The etiology of multiple sclerosis (MS) involves multifaceted interactions between genetic loci and environmental factors. Smoking is an important risk factor for MS that overall increases the risk of the disease with approximately 50%. However, the precise effects of smoking on MS development vary considerably in different contexts and in different populations. This review focuses on the influence of smoking on MS risk and its interaction with genetics in MS etiology. The possible biological mechanisms are presented in this paper. Further research is needed to establish the mechanisms of causality and to explore preventive strategies.

Maternal and Perinatal Exposures Are Associated With Risk for Pediatric-Onset Multiple Sclerosis

OBJECTIVE

To determine if prenatal, pregnancy, or postpartum-related environmental factors are associated with multiple sclerosis (MS) risk in children.

METHODS

This is a case-control study of children with MS or clinically isolated syndrome and healthy controls enrolled at 16 clinics participating in the US Network of Pediatric MS Centers. Parents completed a comprehensive environmental questionnaire, including the capture of pregnancy and perinatal factors. Case status was confirmed by a panel of 3 pediatric MS specialists. Multivariable logistic regression analyses were used to determine association of these environmental factors with case status, adjusting for age, sex, race, ethnicity, US birth region, and socioeconomic status.

RESULTS

Questionnaire responses were available for 265 eligible cases (median age 15.7 years, 62% girls) and 412 healthy controls (median age 14.6, 54% girls). In the primary multivariable analysis, maternal illness during pregnancy was associated with 2.3-fold increase in odds to have MS (95% confidence interval [CI] 1.20-4.21, P = .01) and cesarean delivery with 60% reduction (95% CI 0.20-0.82, P = .01). In a model adjusted for these variables, maternal age and BMI, tobacco smoke exposure, and breastfeeding were not associated with odds to have MS. In the secondary analyses, after adjustment for age, sex, race, ethnicity, and socioeconomic status, having a father who worked in a gardening-related occupation (odds ratio [OR] 2.18, 95% CI 1.14-4.16, P = .02) or any use in household of pesticide-related products (OR 1.73, 95% CI 1.06-2.81, P = .03) were both associated with increased odds to have pediatric MS.

CONCLUSION

Cesarean delivery and maternal health during pregnancy may influence risk for pediatric-onset MS. We report a new possible association of pesticide-related environmental exposures with pediatric MS that warrants further investigation and replication.