Multiple sclerosis: an immune attack on astrocyte-mediated ion and water homeostasis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS. The chain of events that results in demyelinating lesions is not understood, although most theories assume a primary immune attack on myelin. However, the glial cell adhesion molecule GlialCAM, which forms part of a protein complex in astrocytic endfeet that is crucial for brain ion and water homeostasis, was recently identified as a target for autoimmunity in patients with MS. This complex also includes the astrocytic transmembrane protein MLC1, the water channel aquaporin 4 (AQP4) and the potassium channel KIR4.1. Autoimmunity against AQP4 underlies another demyelinating disorder, neuromyelitis optica, and autoimmunity against KIR4.1 has been implicated in a subtype of MS. Genetic defects in any of these proteins cause leukodystrophies with disruption of brain ion and water homeostasis, which is regulated by astrocytes and secondarily affects myelin. In this Perspective, we argue that an immune attack on the ion and water homeostasis machinery in astrocytic endfeet, rather than directly on myelin, is the primary event in MS and that myelin damage is a consequence of astrocyte dysfunction. This hypothesis is supported by pathological studies on tissue from people with MS and has important implications for disease models and therapy targets.

History of head trauma and the risk of multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Multiple sclerosis (MS) is a chronic disease of the central nervous system with unclear etiology involving genetic, environmental, and immunological factors. The potential link between head trauma and MS is controversial, with conflicting evidence. This systematic review and meta-analysis aim to assess the risk of developing MS following head trauma.

METHODS

A systematic search of electronic databases was conducted, including studies that investigated the risk of MS in individuals with a history of head trauma compared to those without. Observational studies, including cohort and case-control designs, were included. Data synthesis was conducted using RevMan software. GRADE was used to assess the certainty of evidence.

RESULTS

Fifteen studies comprising 1,619,640 participants were included in the meta-analysis. The overall odds of developing MS were significantly higher in the head trauma group compared to the control group (OR = 1.41;95 % CI = [1.23, 1.61]; P < 0.00001; I2 = 62 %). Sensitivity analyses based on the number of participants and quality further supported our results. Subgroup analysis showed that results remained consistent across different head trauma identification methods (P = 0.92), early age head trauma and head trauma defined as TBI, or concussion were also significant predictors of MS (P < 0.0001). Analysis of the number of hits suggested a dose-response relationship between the number of head injuries and the risk of MS. According to the GRADE, all outcomes were classified as low or very low certainty of the evidence.

CONCLUSION

This meta-analysis suggests that a history of head trauma may be associated with an increased risk of developing MS. Further research is warranted to support our findings and explore the mechanisms linking head trauma to MS.

Head trauma results in manyfold increased risk of multiple sclerosis in genetically susceptible individuals

BACKGROUND

Large register-based studies have reported an association between head trauma and increased risk of multiple sclerosis (MS). We aimed to investigate possible interactions between head trauma and MS-associated HLA genes in relation to MS risk.

METHODS

We used a Swedish population-based case-control study (2807 incident cases, 5950 matched controls with HLA genotypes available for 2057 cases, 2887 controls). Subjects with and without a history of self-reported head trauma were compared regarding MS risk, by calculating ORs with 95% CIs using logistic regression models. Additive interaction between head trauma, HLA-DRB1*1501 and absence of HLA-A*0201, was assessed by calculating the attributable proportion (AP) due to interaction.

RESULTS

A history of head trauma was associated with a 30% increased risk of subsequently developing MS (OR 1.34, 95% CI 1.17 to 1.53), with a trend showing increased risk of MS with increasing number of head impacts (p=0.03). We observed synergistic effects between recent head trauma and HLA-DRB1*15:01 as well as absence of HLA*02:01 in relation to MS risk (each AP 0.40, 95% CI 0.1 to 0.7). Recent head trauma in individuals with both genetic risk factors rendered an 18-fold increased risk of MS, compared with those with neither the genetic risk factors nor a history of head trauma (OR 17.7, 95% CI 7.13 to 44.1).

CONCLUSIONS

Our findings align with previous observations of a dose-dependent association between head trauma and increased risk of MS and add a novel aspect of this association by revealing synergistic effects between recent head trauma and MS-associated HLA genes.

Pediatric traumatic brain injury and early age multiple sclerosis in Finland: A nationwide register-based cohort study

OBJECTIVE

Examine the link between pediatric traumatic brain injury (pTBI) and early-onset multiple sclerosis in Finland.

METHODS

Conducted nationwide register study (1998-2018) with 28,750 pTBI patients (< 18) and 38,399 pediatric references with extremity fractures. Multiple sclerosis diagnoses from Finnish Social Insurance Institution. Employed Kaplan-Meier and multivariable Cox regression for probability assessment, results presented with 95% CI.

RESULTS

Of 66 post-traumatic multiple sclerosis cases, 30 (0.10%) had pTBI, and 36 (0.09%) were in the reference group. Cumulative incidence rates (CIR) in the first 10 years were 46.5 per 100,000 (pTBI) and 33.1 per 100,000 (reference). Hazard ratio (HR) for pTBI was 1.10 (95% CI: 0.56-1.48).Stratified by gender, women's CIR was 197.9 per 100,000 (pTBI) and 167.0 per 100,000 (reference) after 15 years. For men, CIR was 44.6 per 100,000 (pTBI) and 34.7 per 100,000 (reference). In the initial 3 years, HR for female pTBI was 1.75 (95% CI: 0.05-6.32), and between years 3 and 20, it was 1.08 (95% CI: 0.51-1.67). For male patients, HR was 1.74 (95% CI: 0.69-4.39).

SIGNIFICANCE

We did not find evidence of an association between pTBI and early-onset multiple sclerosis 20 years post-initial trauma.

Blood-brain barrier dysfunction in multiple sclerosis: causes, consequences, and potential effects of therapies

Established by brain endothelial cells, the blood-brain barrier (BBB) regulates the trafficking of molecules, restricts immune cell entry into the CNS, and has an active role in neurovascular coupling (the regulation of cerebral blood flow to support neuronal activity). In the early stages of multiple sclerosis, around the time of symptom onset, inflammatory BBB damage is accompanied by pathogenic immune cell infiltration into the CNS. In the later stages of multiple sclerosis, dysregulation of neurovascular coupling is associated with grey matter atrophy. Genetic and environmental factors associated with multiple sclerosis, including dietary habits, the gut microbiome, and vitamin D concentrations, might contribute directly and indirectly to brain endothelial cell dysfunction. Damage to brain endothelial cells leads to an influx of deleterious molecules into the CNS, accelerating leakage across the BBB. Potential future therapeutic approaches might help to prevent BBB damage (eg, monoclonal antibodies targeting cell adhesion molecules and fibrinogen) and help to repair BBB dysfunction (eg, mesenchymal stromal cells) in people with multiple sclerosis.

Relationship between medical history and multiple sclerosis: A-case-control study

This project sought to explore the potential association between medical history and the development of multiple sclerosis (MS) by conducting a retrospective study. This population-based case-control study included 200 MS cases and 2 control groups of 200 patients and healthy individuals each. Data was collected through face-to-face interviews, medical file reviews, and an electronic checklist. Multivariable analysis was used to calculate odds ratios and 95% confidence intervals to estimate the risk of each medical history on MS occurrences. Of 600 participants, 381 (63.5%) individuals were female. The mean age of the participants was 36.5 ± 11.9 years. The adjusted risks of MS were 4.40; 95% CI: 1.73 to 11.1 for measles and 4.75; 95% CI: 2.05 to 11 for amoxicillin consumption. The adjusted MS odds for autoimmune disease including 4.63; 95% CI: 0.35 to 60.6 for psoriasis and 7.15; 95% CI: 1.87 to 27.2 for myasthenia gravis. On the other hand, the calculated adjusted odds of MS occurrence were 0.14; 95% CI: 0.03 to 0.69 for seizure and 0.17; 95% CI: 0.02 to 1.49 for epilepsy. This study suggested that individuals with autoimmune diseases should be monitored more closely, as they may be at an increased risk of developing other autoimmune conditions, particularly MS.

Sport-Related Concussion: A Cognitive Perspective

Purpose of Review

The incidence of sport-related concussion (SRC) has been increasing in different sports and its impact on long-term cognitive function is increasingly recognized. In this study, we review the epidemiology, neuropathophysiology, clinical symptoms, and long-term consequences of SRC with a specific focus on cognition.

Recent Findings

Repeated concussions are associated with an increased risk of several neurologic diseases and long-term cognitive deficits. To improve cognitive outcomes in athletes with SRC, standardized guidelines for the assessment and management of SRC are vital. However, current concussion management guidelines lack procedures for rehabilitating acute and long-term cognitive symptoms.

Summary

Increased awareness for the management and rehabilitation of cognitive symptoms in SRC is needed in all clinical neurologists treating professional and amateur athletes. We propose cognitive training as a prehabilitation tool to alleviate the severity of cognitive symptoms and as a rehabilitative tool to improve cognitive recovery postinjury.

Myopia in late adolescence and subsequent multiple sclerosis among men

BACKGROUND

Risk factors such as low vitamin D level has been implicated in the etiology of multiple sclerosis (MS) and may be relevant to myopia, such that there may be an association between myopia and MS.

METHODS

Using linked Swedish national register data, we conducted a cohort study of men who were born in Sweden between 1950 and 1992, lived in Sweden between 1990 and 2018, and enrolled in military conscription assessment (n = 1,847,754). Myopia was defined based on the spherical equivalent refraction measured at conscription assessment, around age 18 years. Multiple sclerosis was identified using the Patient Register. Cox regression produced hazard ratios (HR) with 95% confidence intervals (95% CI), with adjustment for demographic and childhood socioeconomic characteristics and residential region. Due to changes in the assessment of refractive error, the analysis was stratified into two groups by the year of conscription assessment: 1969-1997 and 1997-2010.

RESULTS

Among 1,559,859 individuals during a maximum of 48 years of follow-up from age 20 to 68 years (44,715,603 person-years), there were 3,134 MS events, and the incidence rate 7.0 (95% CI [6.8, 7.3] per 100,000 person-years). Among individuals with conscription assessments during 1997-2010, there were 380 MS events. There was no evidence of an association between myopia and MS, with HR 1.09 (95% CI 0.83, 1.43). Among individuals who underwent conscription assessment in 1969-1997, there were 2754 MS events. After adjusting for all covariates, there was no evidence of an association between myopia and MS (HR 0.99 [95% CI 0.91, 1.09]).

CONCLUSION

Myopia in late adolescence is not associated with a subsequent raised risk of MS and thus there does not appear to be important shared risk factors.

Increasing incidence of pediatric mild traumatic brain injury in Finland - a nationwide register study from 1998 to 2018

AIM

The purpose of this study is to document the annual incidence and incidence trends of pediatric traumatic brain injury (pTBI) in Finland over the course of 21 years.

METHODS

We conducted a retrospective nationwide register-based cohort study and used the Finnish Care Register and Population information statistics from 1998 to 2018. The patient group includes all patients aged <18 at the time of injury. We included all emergency department (ED) visits and subsequent inpatient admissions (meaning at least one night in the hospital) with International Classification of Diseases diagnostic code S06*. We calculated pTBI incidences per 100,000 person-years with 95% confidence intervals and the incidences were compared by incidence rate ratios (IRR), including age, diagnosis, and gender stratified analyses.

RESULTS

A total of 71,972 patients were included with 76,785 ED visits or hospitalizations for pTBI diagnoses. The annual incidence of diagnosed pTBI was 251 (CI: 241-260) per 100,000 in 1998 and 547 (CI: 533-561) per 100,000 in 2018, indicating a 118% increase in the incidence (IRR 2.18 CI: 2.09-2.28). Boys had 32% higher incidence (IRR 1.32 CI: 1.30-1.34) than girls. The highest cumulative incidence was observed among boys aged <1 years, 525 (CI: 507-543) per 100,000, and boys had higher incidences in all age groups. The most used diagnostic code was concussion, which included 92.1% of the diagnoses followed by diffuse brain injury, which included 2.3% of the diagnoses. The increase in the incidence of diagnosed pTBI was notably high after 2010. Concussion diagnoses and pTBI cases that were discharged directly from the ED had more than a two-fold increase from 2010 to 2018, whereas the incidence of inpatient admissions for pTBI increased by 53%.

CONCLUSIONS

The overall incidence of diagnosed pTBI has increased in Finland especially since 2010. Boys have higher incidence of diagnosed pTBI in all age groups. Most of the increase was due to increase in the concussion diagnoses, which may be due to the centralization of EDs into bigger units and increased diagnostic awareness of mild pTBI.

Co-administration of Nanowired Oxiracetam and Neprilysin with Monoclonal Antibodies to Amyloid Beta Peptide and p-Tau Thwarted Exacerbation of Brain Pathology in Concussive Head Injury at Hot Environment

Environmental temperature adversely affects the outcome of concussive head injury (CHI)-induced brain pathology. Studies from our laboratory showed that animals reared at either cold environment or at hot environment exacerbate brain pathology following CHI. Our previous experiments showed that nanowired delivery of oxiracetam significantly attenuated CHI-induced brain pathology and associated neurovascular changes. Military personnel are the most susceptible to CHI caused by explosion, blasts, missile or blunt head trauma leading to lifetime functional and cognitive impairments affecting the quality of life. Severe CHI leads to instant death and/or lifetime paralysis. Military personnel engaged in combat operations are often subjected to extreme high or low environmental temperature zones across the globe. Thus, further exploration of novel therapeutic agents at cold or hot ambient temperatures following CHI are the need of the hour. CHI is also a major risk factor for developing Alzheimer's disease by enhancing amyloid beta peptide deposits in the brain. In this review, effect of hot environment on CHI-induced brain pathology is discussed. In addition, whether nanodelivery of oxiracetam together with neprilysin and monoclonal antibodies (mAb) to amyloid beta peptide and p-tau could lead to superior neuroprotection in CHI is explored. Our results show that co-administration of oxiracetam with neprilysin and mAb to AβP and p-tau significantly induced superior neuroprotection following CHI in hot environment, not reported earlier.

Repeated mild traumatic brain injuries in mice cause age- and sex-specific alterations in dendritic spine density

Mild traumatic brain injuries (mTBI) plague the human population and their prevalence is increasing annually. More so, repeated mTBIs (RmTBI) are known to manifest and compound neurological deficits in vulnerable populations. Age at injury and sex are two important factors influencing RmTBI pathophysiology, but we continue to know little about the specific effects of RmTBI in youth and females. In this study, we directly quantified the effects of RmTBI on adolescent and adult, male and female mice, with a closed-head lateral impact model. We report age- and sex-specific neurobehavioural deficits in motor function and working memory, microglia responses to injury, and the subsequent changes in dendritic spine density in select brain regions. Specifically, RmTBI caused increased footslips in adult male mice as assessed in a beam walk assay and significantly reduced the time spent with a novel object in adolescent male and female mice. RmTBIs caused a significant reduction in microglia density in male mice in the motor cortex, but not female mice. Finally, RmTBI significantly reduced dendritic spine density in the agranular insular cortex (a region of the prefrontal cortex in mice) and increased dendritic spine density in the adolescent male motor cortex. Together, the data provided in this study sheds new light on the heterogeneity in RmTBI-induced behavioural, glial, and neuronal architecture changes dependent on age and sex.

Inflammation and the role of infection: Complications and treatment options following neurotrauma

Traumatic brain injury can have devastating consequences for patients and extended hospital stays and recovery course. Recent data indicate that the initial insult causes profound changes to the immune system and leads to a pro-inflammatory state. This alteration in homeostasis predisposes patients to an increased risk of infection and underlying autoimmune conditions. Increased emphasis has been placed on understanding this process both in the clinical and preclinical literature. This review highlights the intrinsic inflammatory conditions that can occur within the initial hospital stay, discusses long-term immune consequences, highlights emerging treatment options, and delves into important pathways currently being investigated with preclinical models.

Case-control study of adverse childhood experiences and multiple sclerosis risk and clinical outcomes

Background

Adverse childhood experiences (ACEs) are linked to numerous health conditions but understudied in multiple sclerosis (MS). This study’s objective was to test for the association between ACEs and MS risk and several clinical outcomes.

Methods

We used a sample of adult, non-Hispanic MS cases (n = 1422) and controls (n = 1185) from Northern California. Eighteen ACEs were assessed including parent divorce, parent death, and abuse. Outcomes included MS risk, age of MS onset, Multiple Sclerosis Severity Scale score, and use of a walking aid. Logistic and linear regression estimated odds ratios (ORs) (and beta coefficients) and 95% confidence intervals (CIs) for ACEs operationalized as any/none, counts, individual events, and latent factors/patterns.

Results

Overall, more MS cases experienced ≥1 ACE compared to controls (54.5% and 53.8%, respectively). After adjusting for sex, birthyear, and race, this small difference was attenuated (OR = 1.01, 95% CI: 0.87, 1.18). There were no trends of increasing or decreasing odds of MS across ACE count categories. Consistent associations between individual ACEs between ages 0–10 and 11–20 years and MS risk were not detected. Factor analysis identified five latent ACE factors, but their associations with MS risk were approximately null. Age of MS onset and other clinical outcomes were not associated with ACEs after multiple testing correction.

Conclusion

Despite rich data and multiple approaches to operationalizing ACEs, no consistent and statistically significant effects were observed between ACEs with MS. This highlights the challenges of studying sensitive, retrospective events among adults that occurred decades before data collection.

Multiple Past Concussions in High School Hockey Players: Examining Cognitive Functioning and Symptom Reporting

OBJECTIVE

To investigate (1) if there are meaningful differences in baseline preseason cognitive functioning or symptom reporting between high school ice hockey players with and without prior concussions and (2) determine which health history variables predict symptom reporting.

DESIGN

Cross-sectional study.

SETTING

High schools across the state of Maine.

PARTICIPANTS

Participants were 1616 male high school ice hockey players (mean age = 15.6 years; SD = 1.5 years) who completed baseline testing between 2009 and 2015.

INDEPENDENT VARIABLES

Athletes were grouped according to their self-reported concussion history [0 (n = 1136), 1 (n = 321), 2 (n = 112), or 3+ (n = 47) previous concussions].

MAIN OUTCOME MEASURES

Cognitive functioning was measured by the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) battery, and symptom ratings were obtained from the Post-Concussion Symptom Scale.

RESULTS

There were no statistically significant differences between groups in cognitive functioning as measured by ImPACT. The group with ≥3 prior concussions endorsed higher total symptom scores, but the effect sizes were small and not statistically significant. In a multivariate model, prior treatment for headaches (not necessarily migraines), prior treatment for a psychiatric condition, and prior treatment for substance/alcohol use all significantly predicted total symptom scores, with concussion history being the weakest independent predictor.

CONCLUSIONS

Players with a history of prior concussions performed similarly to players with no prior concussions on cognitive testing. Health history factors were more strongly associated with symptom reporting than concussion history.

Association of Infectious Mononucleosis in Childhood and Adolescence With Risk for a Subsequent Multiple Sclerosis Diagnosis Among Siblings

IMPORTANCE

Epstein-Barr virus and its acute manifestation, infectious mononucleosis (IM), are associated with an increased risk of multiple sclerosis (MS). Whether this association is confounded by susceptibility to infection is still debated.

OBJECTIVE

To assess whether hospital-diagnosed IM during childhood, adolescence, or young adulthood is associated with subsequent MS diagnosis independent of shared familial factors.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study used the Swedish Total Population Register to identify individuals born in Sweden from January 1, 1958, to December 31, 1994. Participants aged 20 years were followed up from January 1, 1978, to December 31, 2018, with a median follow-up of 15.38 (IQR, 8.68-23.55; range, 0.01-40.96) years. Data were analyzed from October 2020 to July 2021.

EXPOSURE

Hospital-diagnosed IM before 25 years of age.

MAIN OUTCOMES AND MEASURES

Diagnoses of MS from 20 years of age were identified. Risk of an MS diagnosis associated with IM in childhood (birth to 10 years of age), adolescence (11-19 years of age), and early adulthood (20-24 years of age [time-dependent variable]) were estimated using conventional and stratified (to address familial environmental or genetic confounding) Cox proportional hazards regression.

RESULTS

Of the 2 492 980 individuals (1 312 119 men [52.63%] and 1 180 861 women [47.37%]) included, 5867 (0.24%) had an MS diagnosis from 20 years of age (median age, 31.50 [IQR, 26.78-37.54] years). Infectious mononucleosis in childhood (hazard ratio [HR], 1.98; 95% CI, 1.21-3.23) and adolescence (HR, 3.00; 95% CI, 2.48-3.63) was associated with an increased risk of an MS diagnosis that remained significant after controlling for shared familial factors in stratified Cox proportional hazards regression (HRs, 2.87 [95% CI, 1.44-5.74] and 3.19 [95% CI, 2.29-4.46], respectively). Infectious mononucleosis in early adulthood was also associated with risk of a subsequent MS diagnosis (HR, 1.89; 95% CI, 1.18-3.05), but this risk was attenuated and was not significant after controlling for shared familial factors (HR, 1.51; 95% CI, 0.82-2.76).

CONCLUSIONS AND RELEVANCE

These findings suggest that IM in childhood and particularly adolescence is a risk factor associated with a diagnosis of MS, independent of shared familial factors.

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.

The multiple sclerosis prodrome

A prodrome is an early set of signs, symptoms or other findings that occur before the onset of typical symptoms of a disease. Prodromal phases are well recognized in several neurological and inflammatory diseases, but the possibility of a prodrome in multiple sclerosis (MS) has received relatively little attention until the past few years. In this Perspective, we summarize what is currently known about the MS prodrome, including its possible duration, clinical features and potential biomarkers. We also consider what insights and lessons can be learned from knowledge of and research into the prodromal phases of other diseases. A better understanding of the MS prodrome could have profound clinical implications as it could enable earlier recognition of MS and earlier initiation of treatments that reduce relapse rates and long-term disability. Knowledge of the MS prodrome could also affect research into the causes of MS, and putative risk factors must be re-evaluated in light of the MS prodrome. We conclude by outlining the major knowledge gaps and propose future initiatives.

Fulminating Autoimmune Demyelination with Optic Neuropathy in a Case of Pediatric Cerebral Adrenoleukodystrophy: Case Report and Review of the Literature

X-linked adrenoleukodystrophy (ALD) is a leukodystrophy characterized not only by progressive loss of myelin in the central nervous system due to dysmyelination, but also by acute, subacute, or chronic inflammatory demyelination. This results in the phenotypic variability of cerebral ALD (cerALD), which is independent of the genotype. In this article, we reported a fulminant presentation with fluctuating encephalopathy and visual loss in a patient with childhood onset cerALD. Brain MRI showed symmetric confluent occipito-temporal demyelination with severe disruption of the blood–brain barrier and prechiasmal optic neuropathy. The patient's cerebral spinal fluid (CSF) demonstrated an elevated IgG index, myelin basic proteins, and oligoclonal bands. Within 48 hours of receiving immunomodulating therapy, the patient's symptoms of psychomotor slowing, visual impairment, and areflexia partially resolved. High plasma C26:0 levels and high ratios of C24/22 and C26/22 were diagnostic of ALD. It has been shown that environmental factors play an important role in the inflammatory demyelination responsible for the severe phenotypes of cerALD.

Multiple sclerosis: doubling down on MHC

Human leukocyte antigen (HLA)-encoded surface molecules present antigenic peptides to T lymphocytes and play a key role in adaptive immune responses. Besides their physiological role of defending the host against infectious pathogens, specific alleles serve as genetic risk factors for autoimmune diseases. For multiple sclerosis (MS), an autoimmune disease that affects the brain and spinal cord, an association with the HLA-DR15 haplotype was described in the early 1970s. This short opinion piece discusses the difficulties of disentangling the details of this association and recent observations about the functional involvement of not only one, but also the second gene of the HLA-DR15 haplotype. This information is not only important for understanding the pathomechanism of MS, but also for antigen-specific therapies.

Hospital-diagnosed infections before age 20 and risk of a subsequent multiple sclerosis diagnosis

The involvement of specific viral and bacterial infections as risk factors for multiple sclerosis has been studied extensively. However, whether this extends to infections in a broader sense is less clear and little is known about whether risk of a multiple sclerosis diagnosis is associated with other types and sites of infections, such as of the CNS. This study aims to assess if hospital-diagnosed infections by type and site before age 20 years are associated with risk of a subsequent multiple sclerosis diagnosis and whether this association is explained entirely by infectious mononucleosis, pneumonia, and CNS infections. Individuals born in Sweden between 1970-1994 were identified using the Swedish Total Population Register (n = 2,422,969). Multiple sclerosis diagnoses from age 20 years and hospital-diagnosed infections before age 20 years were identified using the Swedish National Patient Register. Risk of a multiple sclerosis diagnosis associated with various infections in adolescence (11-19 years) and earlier childhood (birth-10 years) was estimated using Cox regression, with adjustment for sex, parental socioeconomic position, and infection type. None of the infections by age 10 years were associated with risk of a multiple sclerosis diagnosis. Any infection in adolescence increased the risk of a multiple sclerosis diagnosis (hazard ratio 1.33, 95% confidence interval 1.21-1.46) and remained statistically significant after exclusion of infectious mononucleosis, pneumonia, and CNS infection (hazard ratio 1.17, 95% confidence interval 1.06-1.30). CNS infection in adolescence (excluding encephalomyelitis to avoid including acute disseminated encephalitis) increased the risk of a multiple sclerosis diagnosis (hazard ratio 1.85, 95% confidence interval 1.11-3.07). The increased risk of a multiple sclerosis diagnosis associated with viral infection in adolescence was largely explained by infectious mononucleosis. Bacterial infections in adolescence increased risk of a multiple sclerosis diagnosis, but the magnitude of risk reduced after excluding infectious mononucleosis, pneumonia and CNS infection (hazard ratio 1.31, 95% confidence interval 1.13-1.51). Respiratory infection in adolescence also increased risk of a multiple sclerosis diagnosis (hazard ratio 1.51, 95% confidence interval 1.30-1.75), but was not statistically significant after excluding infectious mononucleosis and pneumonia. These findings suggest that a variety of serious infections in adolescence, including novel evidence for CNS infections, are risk factors for a subsequent multiple sclerosis diagnosis, further demonstrating adolescence is a critical period of susceptibility to environmental exposures that raise the risk of a multiple sclerosis diagnosis. Importantly, this increased risk cannot be entirely explained by infectious mononucleosis, pneumonia, or CNS infections.

Epstein Barr virus infection and immune defense related to HLA-DR15: consequences for multiple sclerosis

MS is a multifactorial disease in which a series of genetic and non‐genetic, environmental factors plays a role in its etiology. In particular, HLA class II alleles, mainly HLADRB1*15:01 (HLA‐DR15), increase the risk for this disease. Out of several environmental factors, and with regard to infections, EBV remains to be a strong candidate, and may synergize with HLA‐DR15 thus increasing the risk for MS. In this issue of the European Journal of Immunology, Zdimerova et al. present highly interesting experimental data using EBV infection in immune‐deficient mice engrafted with human immune cells, either HLA‐DR15⁺ or HLA‐DRB1*04:01 (HLA DR4), here after denoted as HLA‐DR15⁻. As a result of EBV infection, the viral load and CD8⁺ cell expansion were conspicuously higher in mice engrafted with HLA‐DR15⁺ compared to HLA‐DR15⁻ mice; and myelin basic protein specific T cells emerged in mice engrafted with HLA‐DR15 bearing cells. This study sheds light on how EBV and the class II DR15 haplotype may jointly predispose and synergize in the etiology of MS.

Systemic inflammation moderates the association of prior concussion with hippocampal volume and episodic memory in high school and collegiate athletes

BACKGROUND

There is a need to determine why prior concussion has been associated with adverse outcomes in some retired and active athletes. We examined whether serum inflammatory markers moderate the associations of prior concussion with hippocampal volumes and neurobehavioral functioning in active high school and collegiate athletes.

METHODS

Athletes (N = 201) completed pre-season clinical testing and serum collection (C-reactive protein [CRP]; Interleukin-6 [IL]-6; IL-1 receptor antagonist [RA]) and in-season neuroimaging. Linear mixed-effects models examined associations of prior concussion with inflammatory markers, self-reported symptoms, neurocognitive function, and hippocampal volumes. Models examined whether inflammatory markers moderated associations of concussion history and hippocampal volume and/or clinical measures.

RESULTS

Concussion history was significantly associated with higher symptom severity, p = 0.012, but not hippocampal volume or inflammatory markers (ps > 0.05). A significant interaction of prior concussion and CRP was observed for hippocampal volume, p = 0.006. Follow-up analyses showed that at high levels of CRP, athletes with two or more prior concussions had smaller hippocampal volume compared to athletes without prior concussion, p = 0.008. There was a significant interaction between prior concussion and levels of IL-1RA on memory scores, p = 0.044, i.e., at low levels of IL-1RA, athletes with two or more concussions had worse memory performance than those without prior concussion (p = 0.014).

CONCLUSION

Findings suggest that certain markers of systemic inflammation moderate the association between prior concussion and hippocampal volume and episodic memory performance. Current findings highlight potential markers for predicting at-risk individuals and identify therapeutic targets for mitigating the long-term adverse consequences of cumulative concussion.

Localised multiple sclerosis-like disease after irradiation of the cervicothoracic spinal cord

BACKGROUND

Radiation has been discussed as a potential causative factor for Multiple Sclerosis (MS). However, it is unresolved whether radiation increases the aggressiveness of the immune system or whether it alters the nervous tissue to become vulnerable to a pre-existing autoimmune attackdisposition. We report a patient with an MS-like disease confined to the irradiated part of his central nervous system (CNS).

CASE REPORT

within the course of a year, a 29 year-old man developed three relapses that were distinguishable regarding their neurological signs and symptoms. Clinically and on MRI, all relapses were localised to the cervico-thoracic spinal cord (sensory level Th6, monoparesis right leg, sign of Lhermitte). Four years before, he had been diagnosed with supradiaphragmatic Hodgkin´s lymphoma stage IIa. Four courses of chemotherapy with the ABVD-protocol and irradiation with 29,5 Gray led to complete tumour remission. Consecutive MR-imaging of the brain and spinal cord revealed fluctuating and partially contrast-enhancing lesions exclusively in those sections of the spinal cord that were localised in the field irradiated four years before. Treatment with pulsed i.v. steroids led to improvement. CSF analysis showed mild pleocytosis and isolated oligoclonal bands. Extensive work-up for differential diagnoses was negative. Genetic sequencing for DNA repair enzymes and in-vitro assays of the patients peripheral blood mononuclear cells for increased sensitivity to irradiation was unrevealing.

CONCLUSION

The fact that this patients MS-like disease was strictly confined to the irradiated parts of the body suggests that the co-occurrence of Hodgkins and MS-like disease was not simple coincidence but that they are pathogenetically linked. An increased aggressiveness of the immune system caused by the radiation is an unlikely explanation as the autoimmune attack would not be expected to spare the non-radiated parts of the CNS. We propose that in our patient the nervous tissue in the radiation clinical target volume was altered by radiation. This alteration of antigenic make-up, in turn, may have enabled an MS-specific autoimmune attack by a pre-existent immunological mechanism. This hypothesis is supported by experimental studies of induction of experimental autoimmune encephalitis (EAE) in irradiated rats.

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.

Higher body mass index at ages 16 to 20 years is associated with increased risk of a multiple sclerosis diagnosis in subsequent adulthood among men

Background:

Evidence for the association between body mass index (BMI) and multiple sclerosis (MS) among men remains mixed.

Objective and methods:

Swedish military conscription and other registers identified MS after age of 20 years and BMI at ages 16–20 years ( N = 744,548).

Results:

Each unit (kg/m2) BMI increase was associated with greater MS risk (hazard ratio and 95% confidence interval = 1.034, 1.016–1.053), independent of physical fitness (1.021, 1.001–1.042). Categorised, overweight and obesity were associated with statistically significant raised MS risk compared to normal weight, but not after adjustment for physical fitness.

Conclusion:

MS risk rises with increasing BMI, across the entire BMI range.

IFN-γ and TNF-α Gene Polymorphisms in Multiple Sclerosis Patients in Northwest Iran

BACKGROUND

Cytokines are polypeptides that play critical roles in immune responses. Gene polymorphisms occurring in the inflammatory cytokines are taking a role in autoimmune diseases, including multiple sclerosis (MS), which may induce inappropriate immune responses.

OBJECTIVE

The aim of this study was to investigate the allelic and genotypic frequencies of interferon gamma gene (IFN-γ) at +874A/T locus and tumor necrosis factor (TNF-α) at+308A/G locus in MS patients of Azeri population.

METHODS

At first, a questionnaire was prepared for each of 240 healthy, non-relative, and 152 Azeri MS patients before obtaining the blood sample from all subjects. After DNA extraction, the frequency of alleles and genotypes of the IFN-γ and TNF-α genes at +874A/T and -308G/A loci, respectively, were determined by allele-specific PCR method. Finally, the frequencies were compared between control and MS patients by chi-square test (x²-test) and p<0.05 was considered significant.

RESULTS

In the IFN-γ +874A/T gene single nucleotide polymorphism (SNP), the most allelic and genotypic frequencies in MS patients were the A allele, 55.26% (p=0.04) and the AT genotype, 52.63% (p=0.048). In healthy individuals, it was 65.42% for the A allele and 45.42% for the AA genotype. For the TNF-α 308 G/A SNP, the highest allelic and genotypic frequencies in MS patients were the G allele with 55.92% (p<0.001) and AG genotype with 61.84%, and in healthy subjects, the allelic and genotypic frequencies were 84.2% and 70.8% for the G allele and GG genotype, respectively.

CONCLUSION

Head trauma, the infection with the herpes virus and Mycoplasma pneumonia, frequent colds and high consumption of canned foods provide grounds for MS. The T allele in the IFN-γ gene (+874) and the genotypes of AA and AG at the TNF-α gene (-308) at the position-308 were considered as potential risk factors for MS. Therefore, the polymorphisms in cytokine genes and following changes in their expression levels can be effective in susceptibility to MS.

Concussion in adolescence and the risk of multiple sclerosis: A retrospective cohort study

BACKGROUND

Physical trauma, specifically concussions sustained during adolescence, has been hypothesized to be a risk factor for multiple sclerosis (MS).

OBJECTIVE

To examine the association between adolescent concussions and future MS diagnosis.

METHODS

This retrospective study using linked administrative databases from Ontario, Canada, identified 97,965 adolescents (age 11-18 years) who sustained ⩾1 concussion and presented to an emergency department between 1992 and 2011. Cases were matched 1:3 with individuals who had not sustained a concussion based on age, sex, address, and index date. The primary outcome was MS diagnosis, using a validated MS diagnosis definition: ⩾1 hospitalization or ⩾5 physician billings within 2 years.

RESULTS

A concussion during adolescence was associated with a significantly increased risk of MS (hazard ratio (HR) = 1.29, p = 0.03). Sex-specific analysis revealed that only males who sustained a concussion in adolescence had a raised risk of MS (HR = 1.41, p = 0.04).

CONCLUSION

This study supports an association between concussions in adolescence and future MS diagnoses, highlighting the potentially serious long-term effects of concussions.

Molecular mimicry between Anoctamin 2 and Epstein-Barr virus nuclear antigen 1 associates with multiple sclerosis risk

Multiple sclerosis (MS) is a chronic inflammatory, likely autoimmune disease of the central nervous system with a combination of genetic and environmental risk factors, among which Epstein-Barr virus (EBV) infection is a strong suspect. We have previously identified increased autoantibody levels toward the chloride-channel protein Anoctamin 2 (ANO2) in MS. Here, IgG antibody reactivity toward ANO2 and EBV nuclear antigen 1 (EBNA1) was measured using bead-based multiplex serology in plasma samples from 8,746 MS cases and 7,228 controls. We detected increased anti-ANO2 antibody levels in MS (P = 3.5 × 10^-36) with 14.6% of cases and 7.8% of controls being ANO2 seropositive (odds ratio [OR] = 1.6; 95% confidence intervals [95%CI]: 1.5 to 1.8). The MS risk increase in ANO2-seropositive individuals was dramatic when also exposed to 3 known risk factors for MS: HLA-DRB1*15:01 carriage, absence of HLA-A*02:01, and high anti-EBNA1 antibody levels (OR = 24.9; 95%CI: 17.9 to 34.8). Reciprocal blocking experiments with ANO2 and EBNA1 peptides demonstrated antibody cross-reactivity, mapping to ANO2 [aa 140 to 149] and EBNA1 [aa 431 to 440]. HLA gene region was associated with anti-ANO2 antibody levels and HLA-DRB1*04:01 haplotype was negatively associated with ANO2 seropositivity (OR = 0.6; 95%CI: 0.5 to 0.7). Anti-ANO2 antibody levels were not increased in patients from 3 other inflammatory disease cohorts. The HLA influence and the fact that specific IgG production usually needs T cell help provides indirect evidence for a T cell ANO2 autoreactivity in MS. We propose a hypothesis where immune reactivity toward EBNA1 through molecular mimicry with ANO2 contributes to the etiopathogenesis of MS.

Incidence, Risk Factors and Outcomes Among Children With Acute Flaccid Myelitis: A Population-based Cohort Study in a California Health Network Between 2011 and 2016

BACKGROUND

Acute flaccid myelitis (AFM) is defined as an acute onset of limb weakness with longitudinal spinal gray matter lesions. Reporting bias and misdiagnosis confound epidemiologic studies of AFM. We mitigated these confounders by using a large data set to assess AFM incidence, risk factors and outcomes in a fixed population.

METHODS

A retrospective cohort study was conducted within Kaiser Permanente Northern California population among children 1-18 years. Cases met radiographic and clinical criteria for AFM and were confirmed by two clinicians. Clinical and demographic data were assessed.

RESULTS

A total of 28 patients met study criteria for AFM between January 1, 2011 and December 31, 2016, an overall rate of 1.46 per 100,000 person-years. Incidence increased from 0.30 to 1.43 cases/per 100,000 person-years between 2011 and 2016, respectively. Median age was 9 years. Risk factors included male sex, Asian ancestry and history of asthma, atopic dermatitis or head injury. Risk factors associated with poliomyelitis were absent. Prodromal illness was common; enterovirus was the most common pathogen detected (n = 5). Among the 27 patients with 12-month follow-up, most demonstrated some improvement, 11 (41.0%) had full recovery, but several had significant deficits with one death reported after the study period.

CONCLUSIONS

We employed a closed-population study to generate AFM incidence, risk and outcome data. Our findings support previous reports of male sex and atopy as risk factors. Interval increase in incidence, predisposing Asian ancestry and history of head injury were unique findings to this study. Overall prognosis was better than prior reports, but recovery was incomplete in several patients.

Validation of the Swedish Multiple Sclerosis Register: Further Improving a Resource for Pharmacoepidemiologic Evaluations

Supplemental Digital Content is available in the text.

The Swedish Multiple Sclerosis Register is a national register monitoring treatment and clinical course for all Swedish multiple sclerosis (MS) patients, with high coverage and close integration with the clinic. Despite its great value for epidemiologic research, it has not previously been validated. In this brief report, we summarize a large validation of >3,000 patients in the register using clinical chart review in the context of the COMBAT-MS study. While further improving the data quality for a central cohort of patients available for future epidemiologic research, this study also allowed us to estimate the accuracy and completeness of the register data.

Autoimmunity After Ischemic Stroke and Brain Injury

Ischemic Stroke is a major cause of morbidity and mortality worldwide. Sterile inflammation occurs after both stroke subtypes and contributes to neuronal injury and damage to the blood-brain barrier with release of brain antigens and a potential induction of autoimmune responses that escape central and peripheral tolerance mechanisms. In stroke patients, the detection of T cells and antibodies specific to neuronal antigens suggests a role of humoral adaptive immunity. In experimental models stroke leads to a significant increase of autoreactive T and B cells to CNS antigens. Lesion volume and functional outcome in stroke patients and murine stroke models are connected to antigen-specific responses to brain proteins. In patients with traumatic brain injury (TBI) a range of antibodies against brain proteins can be detected in serum samples. In this review, we will summarize the role of autoimmunity in post-lesional conditions and discuss the role of B and T cells and their potential neuroprotective or detrimental effects.

Turned Inside Out: Will Myelin-Protective Therapies Become the Next-Generation Anti-Inflammatories?

The earliest and most proximal triggers of inflammatory demyelination in multiple sclerosis (MS) remain an open question. In this DNACB review we address experimental and clinical evidence consistent with subtle perturbations of the axo-myelinic compartment of central nervous system white matter as initiation sites of secondary autoimmune demyelination in MS. Strengthened by experimental evidence that by inhibiting myelinopathy one can prevent inflammatory demyelination, myelin-protective therapies may represent a new class of anti-inflammatory medications for combating myelin autoimmunity.

Neuroanesthesiology Update

We provide a synopsis of innovative research, recurring themes, and novel experimental findings pertinent to the care of neurosurgical patients and critically ill patients with neurological diseases. We cover the following broad topics: general neurosurgery, spine surgery, stroke, traumatic brain injury, monitoring, and anesthetic neurotoxicity.

Acute concussion: making the diagnosis and state of the art management

PURPOSE OF REVIEW

Concussion is an increasingly common injury in children. We aim to review the basic epidemiology and management of acute concussion and highlight recent studies that have contributed to our understanding of care for this injury.

RECENT FINDINGS

While concussion is considered a 'mild' form of traumatic brain injury, recent evidence suggests that as many as 30% of children are still symptomatic 1 month after injury. Although there is increasing interest in finding objective measures of injury and recovery, emerging imaging and serum biomarkers are not ready for routine clinical use. Identification of children at risk for prolonged symptoms is vital. Prolonged rest after injury may worsen outcomes.

SUMMARY

Concussion is a common injury in children. Objective measures of injury and recovery are needed, as are targeted therapies to mitigate the risk of prolonged recovery after injury.

Evaluation and Management of Concussion in Young Athletes

Learning about concussion diagnosis and management is important for all individuals who will be taking care of young athletes. There are about 1.7million reported concussions per year, and, of these, about 20% are sports related. There are risks in all sports, but the highest rates of concussions are from football, rugby, and hockey, with soccer being the highest cause for girls. An on-field assessment includes evaluating airway, breathing, and circulation, followed by cervical spine assessment. Then, concussion evaluation tools can be used to aid in making the diagnosis. While concussion symptoms for the majority of youth resolve within a few weeks, some individuals may have persistence of symptoms for 3 months or more, referred to as postconcussive syndrome. Providers should consider ongoing symptoms in assessing when an athlete may safely return to sports and to learning. A major concern that has become more apparent in recent years is the possibility that concussions may have a longitudinal effect on health, such as in the development of chronic traumatic encephalopathy. Research has shown that there is an increase in the number of patients presenting to their primary care physician with concussions. Knowing how best to prevent, diagnose, and manage concussions will help to minimize risks to young athletes.