Environmental factors related to multiple sclerosis progression

Multiple Sclerosis (MS) is a complex neurological disease which prevalence is increasing worldwide. The impact of environmental factors on MS susceptibility has already been defined and highlighted in many previous reports, particularly vitamin D or ultraviolet B light exposure, Epstein-Barr virus (EBV) infection, obesity, and smoking. There is increasing evidence that environmental and lifestyle factors are not only important in triggering MS but are also implicated in MS progression. Low sun exposure and vitamin D deficiency exhibit a strong relationship with disease progression in both animal and human studies. The gestational period seems also to impact long-term disease progression as January's babies had a higher risk of requiring walking assistance than those born in other months. The implication of EBV in neurodegeneration and MS progression was also suggested even though its specific targets and mechanisms are still unclear. Cigarette smoking is correlated with faster clinical progression. The association of obesity and smoking seems to be associated with a faster progression and an increased rate of brain atrophy. Although the effect of air pollution on MS pathogenesis remains not fully understood, exposure to polluted air can stimulate several mechanisms that might contribute to MS severity. People with MS with active disease have an altered microbiota compared to patients in the remission phase. Cardiovascular comorbidities, epilepsy, and depression are also associated with a more severe disability accrual. Knowledge about MS modifiable risk factors of progression need to be incorporated into everyday clinical practice in order to ameliorate disease outcomes.

Epstein-Barr virus infection as potential indicator of the occurrence and clinical presentation of systemic lupus erythematosus

Introduction

The relationship between Systemic lupus erythematosus (SLE) and Epstein-Barr virus (EBV) infection has been suggested for decades, but the underlying mechanism of the EBV influence on SLE development remains to be elucidated.

Methods

The goals of this research, which included 103 SLE patients and 99 controls, were to investigate the association of the parameters of EBV infection and SLE, to explore whether pooled demographic, clinical and EBV markers achieve a more significant effect on SLE development than each of them individually, and to evaluate EBV nuclear antigen 1 (EBNA1) and latent membrane protein 1 (LMP1) gene polymorphisms in isolates from SLE patients.

Results

Comprehensive results related to serological, molecular and sequence markers of EBV infection in SLE patients demonstrated even 24 times higher possibility of having SLE if there is the presence of anti-EBV-EA(D) (early antigen) IgG antibodies (OR=24.086 95%CI OR=2.86-216.07, p=0.004). There was the same distribution of glucocorticoids (p=0.130), antimalarials (p=0.213), and immunosuppressives (p=0.712) in anti-EBV-EA(D) IgG positive and negative SLE patients. Further, higher anti-EBV-EA(D) IgG antibodies titers were identified as independent factors associated with lymphopenia, hematological SLE manifestation (OR=1.041, 95%CI OR=1.01-1.08, p=0.025, while a higher titer of anti-CA (viral capsid antigen) IgG antibodies (OR=1.015, 95%CI OR=1.01-1.03, p=0.019) and positive RF (rheumatoid factors) (OR=4.871, 95%CI OR=1.52-15.61, p=0.008) were identified as independent factors associated with alopecia within SLE. Finally, novel data on EBV EBNA1 and LMP1 gene polymorphisms in lupus are reported.

Conclusion

The results support further investigation targeting EBV as a prognostic marker and therapeutic goal for lupus.

Joint effect of highly-sensitive cardiac troponin T and ankle-brachial index on incident cardiovascular events: The MESA and CHS

Background

Elevated highly-sensitive cardiac troponin-T (hs-cTnT≥14 ng/L) and low ankle-brachial index (ABI<0.9) are risk factors for atherosclerotic cardiovascular diseases (ASCVD) but their joint effect on the risk of ASCVD events is unknown.

Methods

We used data from the two population-based cohort studies, the Multi-Ethnic study of Atherosclerosis (MESA) and Cardiovascular Heart Study (CHS) among 10,897 participants free of CVD events at baseline (mean age 66.3 years, 44.7% males). Incident ASCVD was defined as CHD (fatal/non-fatal MI or revascularization), transient ischemic attack, or stroke,. Hazard ratio (HR) and 95% CI was calculated from a Cox regression model. Interaction on the additive scale was assessed using relative excess risk due to interaction (RERI) and interaction on the multiplicative scale was assessed by Likelihood ratio (LR) test.

Results

At baseline (2000-2002 for MESA and 1989-1990 for CHS), 10.2% of participants had elevated hs-cTnT and 7.5% had low ABI. During a median follow-up of 13.6 years (interquartile range, 7.5-14.7 years), there were 2590 incident ASCVD and 1542 incident CHD events. The hazard of CHD and ASCVD was higher in participants with both elevated hs-cTnT and low ABI [HR(95% CI): CHD: 2.04 (1.45, 2.88), ASCVD: 2.05 (1.58, 2.66)] than those with only elevated hs-cTnT [CHD: 1.65 (1.37, 1.99), ASCVD: 1.67 (1.44, 1.99)] or only low ABI [CHD: 1.87 (1.52, 2.31), ASCVD: 1.67 (1.42, 1.97)]. Antagonistic multiplicative interaction was observed for CHD (LR test p-value=0.042) but not for ASCVD (LR test p-value =0.08). No significant additive interaction was detected for CHD and ASCVD (RERI p-value ≥0.23).

Conclusion

The observed joint effect of elevated cTnT and low ABI on ASCVD risk was smaller (i.e., antagonistic interaction) than that expected by the combined independent effects of each risk factor.

Trends in the environmental risks associated with earlier onset in multiple sclerosis

BACKGROUND

Several environmental and lifestyle factors relating to sunlight/vitamin D, body mass index (BMI), and smoking are associated with the risk of developing multiple sclerosis (MS). However, their relation to disease progression, particularly age at symptomatic onset, remains inconsistent, which may be the result of significant changes in human-environment interactions over the last century. This study investigates historical trends in the association between common MS environmental risk factors and age at disease onset.

METHODS

Using a narrative approach, we evaluated the current literature for published studies assessing the association between vitamin-D, BMI, and tobacco smoking exposures with the risk of early/pediatric-onset MS and direct correlations with age at MS onset using MEDLINE, EMBASE, and Web of Science. Measures were plotted by the average calendar year of disease onset for each cohort to examine trends over time. In total, 25, 9, and 11 articles were identified for vitamin D, BMI, and smoking-related exposures, respectively.

RESULTS

Higher sun exposure habits and residential solar radiation were associated with older age at onset. On the contrary, two studies observed a negative correlation between age at onset and serum 25-hydroxyvitamin D (25(OH)D) levels. Higher adolescent BMI was generally associated with younger age at onset, although genetic susceptibility for childhood obesity was not significantly associated. Tobacco smoking was associated with later disease onset, despite being a risk factor for MS. Association with age at onset was inflated for more recent studies relating to smoking, while often weaker for serum vitamin D and BMI.

CONCLUSION

Current findings indicate a likely association between age at onset and environmental risk factors, such as sun exposure, adolescent BMI, and tobacco smoking, in certain populations. However, findings are often inconsistent and assessment of the relationships and potential changes over time require further investigation.

A preliminary study of association of cigarette smoking with risk of neuromyelitis optica spectrum disorder

ABSTRACT

Various studies have revealed an association between cigarette smoking and increased risk for multiple sclerosis (MS). However, its role in neuromyelitis optica spectrum disorder (NMOSD) remains elusive. Therefore, in the present case-control study, we aimed to assess the association of active and passive cigarette smoking with the risk of MS and NMOSD.Thirty-six patients with NMOSD, 46 patients with MS, and 122 healthy individuals were included in this study. Standardized questionnaires and telephone interviews were used to collect information regarding the active and passive cigarette smoking behaviors of the patients and normal controls.The risk of MS was significantly higher among smokers than among nonsmokers (odds ratio = 2.166, 95% confidence interval: 1.109-4.170; P = .027). Further analysis of the risk between active and passive smokers, male smokers and nonsmokers showed no statistical difference. However, neither smokers nor active smokers had a greater or lower risk of NMOSD than their nonsmoking counterparts.Our preliminary study showed no significant association between cigarette smoking and the risk of NMOSD, strongly suggesting that, unlike MS, cigarette smoking might not confer NMOSD susceptibility, at least in the Northern Han Chinese population.

High antibody levels against human herpesvirus-6A interact with lifestyle factors in multiple sclerosis development

BACKGROUND

Infection with human herpesvirus 6A (HHV-6A) has been suggested to increase multiple sclerosis (MS) risk. However, potential interactions between HHV-6A and environmental/lifestyle risk factors for MS have not previously been studied.

METHODS

We used two Swedish population-based case-control studies comprising 5993 cases and 5995 controls. Using logistic regression models, subjects with different HHV-6A antibody levels, environmental exposures, and lifestyle habits were compared regarding MS risk, by calculating odds ratios (ORs) with 95% confidence intervals (CIs). Potential interactions between high HHV-6A antibody levels and common environmental exposures and lifestyle factors were evaluated on the additive scale.

RESULTS

High HHV-6A antibody levels were associated with increased risk of developing MS (OR = 1.5, 95% CI = 1.4-1.6). Regarding MS risk, significant interactions were observed between high HHV-6A antibody levels and both smoking (attributable proportion (AP) = 0.2, 95% CI = 0.1-0.3), low ultraviolet radiation (UVR) exposure (AP = 0.3, 95% CI = 0.1-0.4), and low vitamin D levels (AP = 0.3, 95% CI = 0.0-0.6).

CONCLUSION

High HHV-6A antibody levels are associated with increased MS risk and act synergistically with common environmental/lifestyle risk factors for MS. Further research is needed to investigate potential mechanisms underlying the interactions presented in this study.

Antibiotic Use and Risk of Multiple Sclerosis: A Nested Case-Control Study in Emilia-Romagna Region, Italy

INTRODUCTION

Known risk factors for multiple sclerosis (MS) include smoking, a low vitamin D status, obesity, and EBV, while the inflammatory feature of the disease strongly suggests the presence of additional infectious agents. The association between use of antibiotics and MS risk that could shed light on these factors is still undetermined. We aimed to evaluate the association between antibiotics and MS risk, in the Emilia-Romagna region (RER), Italy.

METHODS

All adult patients with MS seen at any RER MS center (2015-2017) were eligible. For each of the 877 patients included, clinical information was collected and matched to 5 controls (RER residents) (n = 4,205) based on age, sex, place of residence, and index year. Information on antibiotic prescription was obtained through the linkage with the RER drug prescription database.

RESULTS

Exposure to any antibiotic 3 years prior to the index year was associated with an increased MS risk (OR = 1.52; 95% CI = 1.29-1.79). Similar results were found for different classes. No dose-response effect was found.

DISCUSSION/CONCLUSIONS

Our results suggest an association between the use of antibiotics and MS risk in RER population. However, further epidemiological studies should be done with information on early life and lifestyle factors.

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.

Increased Serological Response Against Human Herpesvirus 6A Is Associated With Risk for Multiple Sclerosis

Human herpesvirus (HHV)-6A or HHV-6B involvement in multiple sclerosis (MS) etiology has remained controversial mainly due to the lack of serological methods that can distinguish the two viruses. A novel multiplex serological assay measuring IgG reactivity against the immediate-early protein 1 from HHV-6A (IE1A) and HHV-6B (IE1B) was used in a MS cohort (8,742 persons with MS and 7,215 matched controls), and a pre-MS cohort (478 individuals and 476 matched controls) to investigate this further. The IgG response against IE1A was positively associated with MS (OR = 1.55, p = 9 × 10-22), and increased risk of future MS (OR = 2.22, p = 2 × 10-5). An interaction was observed between IE1A and Epstein-Barr virus (EBV) antibody responses for MS risk (attributable proportion = 0.24, p = 6 × 10-6). In contrast, the IgG response against IE1B was negatively associated with MS (OR = 0.74, p = 6 × 10-11). The association did not differ between MS subtypes or vary with severity of disease. The genetic control of HHV-6A/B antibody responses were located to the Human Leukocyte Antigen (HLA) region and the strongest association for IE1A was the DRB1*13:01-DQA1*01:03-DQB1*06:03 haplotype while the main association for IE1B was DRB1*13:02-DQA1*01:02-DQB1*06:04. In conclusion a role for HHV-6A in MS etiology is supported by an increased serological response against HHV-6A IE1 protein, an interaction with EBV, and an association to HLA genes.

The role of Epstein-Barr virus in multiple sclerosis: from molecular pathophysiology to in vivo imaging

Multiple sclerosis (MS) is a disease of the central nervous system characterized by inflammation, demyelination, and neuronal damage. Environmental and genetic factors are associated with the risk of developing MS, but the exact cause still remains unidentified. Epstein-Barr virus (EBV), vitamin D, and smoking are among the most well-established environmental risk factors in MS. Infectious mononucleosis, which is caused by delayed primary EBV infection, increases the risk of developing MS. EBV may also contribute to MS pathogenesis indirectly by activating silent human endogenous retrovirus-W. The emerging B-cell depleting therapies, particularly anti-CD20 agents such as rituximab, ocrelizumab, as well as the fully human ofatumumab, have shown promising clinical and magnetic resonance imaging benefit. One potential effect of these therapies is the depletion of memory B-cells, the primary reservoir site where EBV latency occurs. In addition, EBV potentially interacts with both genetic and other environmental factors to increase susceptibility and disease severity of MS. This review examines the role of EBV in MS pathophysiology and summarizes the recent clinical and radiological findings, with a focus on B-cells and in vivo imaging. Addressing the potential link between EBV and MS allows the better understanding of MS pathogenesis and helps to identify additional disease biomarkers that may be responsive to B-cell depleting intervention.

Lifestyle factors and disease-specific differences in subgroups of Swedish Myasthenia Gravis

PURPOSE

To evaluate disease-specific differences between Myasthenia Gravis (MG) subgroups and compare patterns of lifestyle between MG patients and population controls.

METHODS

All MG patients (n = 70) in Jönköping County, Sweden, were invited to answer a disease-specific questionnaire, containing questions about disease-specific data, lifestyle, comorbidity, and mental fatigue. The patients were clinically evaluated. Four hundred age- and gender-matched population controls were invited to answer the nondisease-specific part of the questionnaire. Disease-specific issues were compared between MG subgroups. Lifestyle-related factors and concomitant conditions were compared to the population controls.

RESULTS

Forty MG patients and 188 population controls participated in the study. In the late-onset MG (LOMG; N = 18) subgroup, the male predominance was higher than previously reported. In the early-onset MG (EOMG; N = 17) subgroup, time to diagnosis was longer, fatigue was higher, and bulbar weakness was the dominant symptom (65%). Compared to their matched population controls, LOMG patients were more obese (OR = 13.7, P = 0.015), ate less fish (OR = 4.1, P = 0.012), tended to smoke more (OR = 4.1, P = 0.086), and tended to be employed as manual laborers more often (OR = 2.82, P = 0.083). Mental health problems and sickness benefits were more common among MG patients than in controls, and MG patients were less regularly doing focused physical activity.

CONCLUSIONS

It is important to consider disease-specific differences when tailoring the management of individual MG patients. There is a need for improved knowledge on how to apply primary and secondary prevention measures to lifestyle disorders in MG patients without risk of deterioration.

The contribution of secondhand tobacco smoke exposure to pediatric multiple sclerosis risk

BACKGROUND

Pediatric acquired demyelinating syndromes (ADSs) are monophasic (mono-ADS) in 70% of cases and represent the first attack of multiple sclerosis (MS) in 30%. Secondhand tobacco smoke (SHS) exposure has been implicated as a risk factor for adult-onset MS. Little is known about whether SHS presents an additive risk beyond genetic factors and other environmental exposures associated with pediatric MS.

METHODS

This study examined SHS exposure in 216 children with mono-ADS and 81 children with MS. Interactions between SHS, HLA-DRB1*15 alleles, serum 25-hydroxyvitamin D concentrations, and serological evidence of remote Epstein-Barr virus (EBV) exposure were evaluated.

RESULTS

SHS exposure was more common in children with MS (37% exposed) compared to mono-ADS (29.5% exposed). Compared to mono-ADS, SHS exposure was not an independent risk factor for MS. When both SHS exposure and HLA-DRB1*15 were present, the odds for MS increased (odds ratio (OR) = 3.7; 95% confidence interval (CI): 1.17-11.9) compared to mono-ADS. Interactions between SHS and vitamin D or EBV did not associate with MS.

CONCLUSION

Exposure to SHS is a risk factor for central nervous system (CNS) demyelination. Results suggest that SHS exposure and HLA-DRB1*15 interact to increase risk for MS in children diagnosed with mono-ADS.

Viruses and endogenous retroviruses in multiple sclerosis: From correlation to causation

Multiple sclerosis is an immune-mediated disease with an environmental component. According to a long-standing but unproven hypothesis dating to initial descriptions of multiple sclerosis (MS) at the end of the 19th century, viruses are either directly or indirectly implicated in MS pathogenesis. Whether viruses in MS are principally causal or simply contributory remains to be proven, but many viruses or viral elements-predominantly Epstein-Barr virus, human endogenous retroviruses (HERVs) and human herpesvirus 6 (HHV-6) but also less common viruses such as Saffold and measles viruses-are associated with MS. Here, we present an up-to-date and comprehensive review of the main candidate viruses implicated in MS pathogenesis and summarize how these viruses might cause or lead to the hallmark demyelinating and inflammatory lesions of MS. We review data from epidemiological, animal and in vitro studies and in doing so offer a transdisciplinary approach to the topic. We argue that it is crucially important not to interpret "absence of evidence" as "evidence of absence" and that future studies need to focus on distinguishing correlative from causative associations. Progress in the MS-virus field is expected to arise from an increasing body of knowledge on the interplay between viruses and HERVs in MS. Such interactions suggest common HERV-mediated pathways downstream of viral infection that cause both neuroinflammation and neurodegeneration. We also comment on the limitations of existing studies and provide future research directions for the field.