Magnetic Resonance Imaging Correlates of Multiple Sclerosis Immunopathological Patterns.

OBJECTIVE: Histology reveals that early active multiple sclerosis lesions can be classified into 3 main interindividually heterogeneous but intraindividually stable immunopathological patterns of active demyelination (patterns I-III). In patterns I and II, a T-cell- and macrophage-associated demyelination is suggested, with pattern II only showing signs of a humoral immune response. Pattern III is characterized by inflammatory lesions with an oligodendrocyte degeneration. Patterns suggest pathogenic heterogeneity, and we postulated that they have distinct magnetic resonance imaging (MRI) correlates that may serve as biomarkers. METHODS: We evaluated in an international collaborative retrospective cohort study the MRI lesion characteristics of 789 conventional prebiopsy and follow-up MRIs in relation to their histopathologically classified immunopathological patterns (n = 161 subjects) and lesion edge features (n = 112). RESULTS: A strong association of a ringlike enhancement and a hypointense T2-weighted (T2w) rim with patterns I and II, but not pattern III, was observed. Only a fraction of pattern III patients showed a ringlike enhancement, and this was always atypical. Ringlike enhancement and T2w rims colocalized, and ringlike enhancement showed a strong association with macrophage rims as shown by histology. A strong concordance of MRI lesion characteristics, meaning that different lesions showed the same features, was found when comparing biopsied and nonbiopsied lesions at a given time point, indicating lesion homogeneity within individual patients. INTERPRETATION: We provide robust evidence that MRI characteristics reflect specific morphological features of multiple sclerosis immunopatterns and that ringlike enhancement and T2w hypointense rims might serve as a valuable noninvasive biomarker to differentiate pathological patterns of demyelination. ANN NEUROL 2021;90:440-454.

Genetic risk factors for pediatric-onset multiple sclerosis.

BACKGROUND: Strong evidence supports the role of both genetic and environmental factors in pediatric-onset multiple sclerosis (POMS) etiology. OBJECTIVE: We comprehensively investigated the association between established major histocompatibility complex (MHC) and non-MHC adult multiple sclerosis (MS)-associated variants and susceptibility to POMS. METHODS: Cases with onset <18 years (n = 569) and controls (n = 16,251) were included from the United States and Sweden. Adjusted logistic regression and meta-analyses were performed for individual risk variants and a weighted genetic risk score (wGRS) for non-MHC variants. Results were compared to adult MS cases (n = 7588). RESULTS: HLA-DRB1*15:01 was strongly associated with POMS (odds ratio (OR)meta = 2.95, p < 2.0 × 10-16). Furthermore, 28 of 104 non-MHC variants studied (23%) were associated (p < 0.05); POMS cases carried, on average, a higher burden of these 28 variants compared to adults (ORavg = 1.24 vs 1.13, respectively), though the difference was not significant. The wGRS was strongly associated with POMS (ORmeta = 2.77, 95% confidence interval: 2.33, 3.32, p < 2.0 × 10-16) and higher, on average, when compared to adult cases. Additional class III risk variants in the MHC region associated with POMS were revealed after accounting for HLA-DRB1*15:01 and HLA-A*02. CONCLUSION: Pediatric and adult MS share many genetic variants suggesting similar biological processes are present. MHC variants beyond HLA-DRB1*15:01 and HLA-A*02 are also associated with POMS.

Clinical and magnetic resonance imaging outcomes in pediatric-onset MS patients on fingolimod and ocrelizumab.

BACKGROUND: Observational studies looking at clinical a++nd MRI outcomes of treatments in pediatric MS, could assess current treatment algorithms, and provide insights for designing future clinical trials. OBJECTIVE: To describe baseline characteristics and clinical and MRI outcomes in MS patients initiating ocrelizumab and fingolimod under 18 years of age. METHODS: MS patients seen at 12 centers of US Network of Pediatric MS were included in this study if they had clinical and MRI follow-up and started treatment with either ocrelizumab or fingolimod prior to the age of 18. RESULTS: Eighty-seven patients initiating fingolimod and 52 initiating ocrelizumab met the inclusion criteria. Before starting fingolimod, mean annualized relapse rate was 0.43 (95 % CI: 0.29 - 0.65) and 78 % developed new T2 lesions while during treatment it was 0.12 (95 % CI: 0.08 - 1.9) and 47 % developed new T2 lesions. In the ocrelizumab group, the mean annualized relapse rate prior to initiation of treatment was 0.64 (95 % CI: 0.38-1.09) and a total of 83 % of patients developed new T2 lesions while during treatment it was 0.09 (95 % CI: 0.04-0.21) and none developed new T2 lesions. CONCLUSION: This study highlights the importance of evaluating current treatment methods and provides insights about the agents in the ongoing phase III trial comparing fingolimod and ocrelizumab.

miRNA contributions to pediatric-onset multiple sclerosis inferred from GWAS.

OBJECTIVE: Onset of multiple sclerosis (MS) occurs in childhood for approximately 5% of cases (pediatric MS, or ped-MS). Epigenetic influences are strongly implicated in MS pathogenesis in adults, including the contribution from microRNAs (miRNAs), small noncoding RNAs that affect gene expression by binding target gene mRNAs. Few studies have specifically examined miRNAs in ped-MS, but individuals developing MS at an early age may carry a relatively high burden of genetic risk factors, and miRNA dysregulation may therefore play a larger role in the development of ped-MS than in adult-onset MS. This study aimed to look for evidence of miRNA involvement in ped-MS pathogenesis. METHODS: GWAS results from 486 ped-MS cases and 1362 controls from the U.S. Pediatric MS Network and Kaiser Permanente Northern California membership were investigated for miRNA-specific signals. First, enrichment of miRNA-target gene network signals was evaluated using MIGWAS software. Second, SNPs in miRNA genes and in target gene binding sites (miR-SNPs) were tested for association with ped-MS, and pathway analysis was performed on associated target genes. RESULTS: MIGWAS analysis showed that miRNA-target gene signals were enriched in GWAS (P = 0.038) and identified 39 candidate biomarker miRNA-target gene pairs, including immune and neuronal signaling genes. The miR-SNP analysis implicated dysregulation of miRNA binding to target genes in five pathways, mainly involved in immune signaling. INTERPRETATION: Evidence from GWAS suggests that miRNAs play a role in ped-MS pathogenesis by affecting immune signaling and other pathways. Candidate biomarker miRNA-target gene pairs should be further studied for diagnostic, prognostic, and/or therapeutic utility.

Author Correction: Neuroimmune disorders of the central nervous system in children in the molecular era.

In the original version of this Review published online and in print, the contribution of attendees of the International Neuroimmune Meeting to the content of the Review was not acknowledged. The author list has been corrected in the PDF and HTML versions of this article to acknowledge that the Review was written on behalf of attendees of the International Neuroimmune Meeting, and the names of the attendees have been added to the HTML version.

Neuroimmune disorders of the central nervous system in children in the molecular era.

Immune-mediated disorders of the CNS in children are a complex group of demyelinating, inflammatory, parainfectious and postinfectious disorders with heterogeneous pathobiological mechanisms and clinical manifestations, often associated with fundamental derangement in immune regulation. In this Review, we aim to provide an update on our knowledge of neuroimmune disorders and highlight areas of research that are priorities for improving clinical management. We outline the clinical features of neuroimmune disorders, the current approaches to their treatment and new approaches in development. We then consider the pathological features, including biomarkers, pathological mechanisms and genetics, and discuss the value of immune assays in clinical investigation and basic research. On the basis of current knowledge and techniques, we propose four research priorities: rigorous and consistent collection of core clinical data, cooperative investigation of treatments, development of biological assays and genetic studies. These priorities should help us to achieve the shared goal of precision medicine for neuroimmune disorders. However, multicentre research and the creation of clinical consortia for these rare disorders will be necessary, and we hope that this Review serves as a call to action that is timely given current exciting advances in neuroimmune therapeutics.

Evidence for a causal relationship between low vitamin D, high BMI, and pediatric-onset MS.

OBJECTIVE: To utilize Mendelian randomization to estimate the causal association between low serum vitamin D concentrations, increased body mass index (BMI), and pediatric-onset multiple sclerosis (MS) using genetic risk scores (GRS). METHODS: We constructed an instrumental variable for vitamin D (vitD GRS) by computing a GRS for 3 genetic variants associated with levels of 25(OH)D in serum using the estimated effect of each risk variant. A BMI GRS was also created that incorporates the cumulative effect of 97 variants associated with BMI. Participants included non-Hispanic white individuals recruited from over 15 sites across the United States (n = 394 cases, 10,875 controls) and Sweden (n = 175 cases, 5,376 controls; total n = 16,820). RESULTS: Meta-analysis findings demonstrated that a vitD GRS associated with increasing levels of 25(OH)D in serum decreased the odds of pediatric-onset MS (odds ratio [OR] 0.72, 95% confidence interval [CI] 0.55, 0.94; p = 0.02) after controlling for sex, genetic ancestry, HLA-DRB1*15:01, and over 100 non-human leukocyte antigen MS risk variants. A significant association between BMI GRS and pediatric disease onset was also demonstrated (OR 1.17, 95% CI 1.05, 1.30; p = 0.01) after adjusting for covariates. Estimates for each GRS were unchanged when considered together in a multivariable model. CONCLUSIONS: We provide evidence supporting independent and causal effects of decreased vitamin D levels and increased BMI on susceptibility to pediatric-onset MS.