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Korn and colleagues report that Sirpα + dendritic cells trans-present the cytokine IL-6 to T cells through a process that requires its receptor IL-6Rα bound to dendritic cells and that trans-presentation is needed to generate pathogenic cells of the T H 17 subset of helper T cells in vivo . The cellular sources of interleukin 6 (IL-6) that are relevant for differentiation of the T H 17 subset of helper T cells remain unclear. Here we used a novel strategy for the conditional deletion of distinct IL-6-producing cell types to show that dendritic cells (DCs) positive for the signaling regulator Sirpα were essential for the generation of pathogenic T H 17 cells. Using their IL-6 receptor α-chain (IL-6Rα), Sirpα + DCs trans-presented IL-6 to T cells during the process of cognate interaction. While ambient IL-6 was sufficient to suppress the induction of expression of the transcription factor Foxp3 in T cells, trans-presentation of IL-6 by DC-bound IL-6Rα (called 'IL-6 cluster signaling' here) was needed to prevent premature induction of interferon-γ (IFN-γ) expression in T cells and to generate pathogenic T H 17 cells in vivo . Our findings should guide therapeutic approaches for the treatment of T H 17-cell-mediated autoimmune diseases.

Multidimensional single-cell analyses of T cells have fueled the debate about whether there is extensive plasticity or ‘mixed’ priming of helper T cell subsets in vivo. Here, we developed an experimental framework to probe the idea that the site of priming in the systemic immune compartment is a determinant of helper T cell–induced immunopathology in remote organs. By site-specific in vivo labeling of antigen-specific T cells in inguinal (i) or gut draining mesenteric (m) lymph nodes, we show that i-T cells and m-T cells isolated from the inflamed central nervous system (CNS) in a model of multiple sclerosis (MS) are distinct. i-T cells were Cxcr6 + , and m-T cells expressed P2rx7. Notably, m-T cells infiltrated white matter, while i-T cells were also recruited to gray matter. Therefore, we propose that the definition of helper T cell subsets by their site of priming may guide an advanced understanding of helper T cell biology in health and disease. Korn and colleagues demonstrate that the site of T cell priming (gut versus skin draining lymph nodes) dictates their effector phenotypes and homing to distal sites of immunopathology.

Genome-wide association studies (GWAS) have identified more than 50,000 unique associations with common human traits. While this represents a substantial step forward, establishing the biology underlying these associations has proven extremely difficult. Even determining which cell types and which particular gene(s) are relevant continues to be a challenge. Here, we conduct a cell-specific pathway analysis of the latest GWAS in multiple sclerosis (MS), which had analyzed a total of 47,351 cases and 68,284 healthy controls and found more than 200 non-MHC genome-wide associations. Our analysis identifies pan immune cell as well as cell-specific susceptibility genes in T cells, B cells and monocytes. Finally, genotype-level data from 2,370 patients and 412 controls is used to compute intra-individual and cell-specific susceptibility pathways that offer a biological interpretation of the individual genetic risk to MS. This approach could be adopted in any other complex trait for which genome-wide data is available. Genome-wide association studies (GWAS) have so far uncovered more than 200 loci for multiple sclerosis (MS). Here, the authors integrate data from various sources for a cell type-specific pathway analysis of MS GWAS results that specifically highlights the involvement of the immune system in disease pathogenesis.

Background Comorbidities in people with multiple sclerosis (PwMS) can affect disease course and quality of life. Objectives To investigate comorbidities in the five years after diagnosis, timing of comorbidity occurrence, age and sex effects, and differences between multiple sclerosis (MS) and other chronic autoimmune diseases (AIDs). Methods In this retrospective cohort study, we systematically assessed differences in diagnosis frequencies in newly diagnosed PwMS (n = 9,880) compared to matched controls (noAID, n = 29,640) and individuals with other AIDs (psoriasis, n = 29,640; Crohn's disease, n = 9,880). Results Some comorbidities of PwMS are similarly frequent in other AIDs, while others, such as depression, are more prevalent in PwMS (odds ratio (OR) vs noAID = 2.03(1.94–2.13)). We found that personality disorders are more frequently recorded in PwMS before (OR  = 1.34(1.21–1.49)) and after MS diagnosis (OR  = 1.32(1.16–1.5)), especially in women (OR  = 1.39(1.2–1.6)). PwMS are more frequently diagnosed with Lyme disease (OR  = 1.98(1.69–2.33)), which was predominantly recorded by general practitioners after presentation with neurological symptoms. We observed lower acute tonsillitis frequencies in PwMS (OR  = 0.8(0.75–0.85)). Conclusions Our results suggest that PwMS might have a generally increased risk for specific personality disorders. More frequent Lyme disease recordings for PwMS suggest misdiagnoses of MS symptoms. Lower tonsillitis frequencies suggest a link between MS and protection from specific infections.

Purpose: The aim of this article is to examine the extent of structural and inflammatory lesions by ultrasound in elderly subjects with hand osteoarthritis (HOA) fulfilling the ACR classification criteria (Group A), in subjects with painless enlarged finger joints (Group B), and in individuals without clinical abnormalities at hands (Group C). Methods: This study was nested within the population-based, prospective Bruneck study; 293 subjects of ⩾65 years of age were assessed. Clinical and ultrasound assessment was conducted at wrists and finger joints. Gray scale synovitis (GSS), Power Doppler (PD), osteophytes, and erosions were scored semiquantitatively (0–3). The Short Form Score for the Assessment and Quantification of Chronic Rheumatic Affections of the Hands (SF-SACRAH), the Health Assessment Questionnaire (HAQ), and the Functional Index for Hand Osteoarthritis (FIHOA) were retrieved. Results: Most subjects had ⩾1 ultrasound abnormality, of which osteophytes were the most prevalent finding in all groups (Group A: 100%, Group B: 99.4%, and Group C: 93.9%). GSS and PD-signals were more common in Group A than in Group B (94% versus 67% and 33% versus 13%, respectively). In Group C, GSS was observed in 39.4% of subjects. In subjects with HOA, the SF-SACRAH correlated with osteophyte scores (corrcoeff = 0.48), and the FIHOA correlated with the osteophyte (corrcoeff = 0.42) and PD scores (corrcoeff = 0.33). Conclusion: GSS and PD were more frequent in patients with symptomatic HOA than in cases with painless bony enlargements and subjects without clinical joint abnormalities. Functional restriction in HOA is associated with structural and inflammatory ultrasound changes.

BackgroundOptical coherence tomography angiography (OCT-A) is a novel technique allowing non-invasive assessment of the retinal vasculature. During relapsing remitting multiple sclerosis (RRMS), retinal vessel loss occurs in eyes suffering from acute optic neuritis and recent data suggest that retinal vessel loss might also be evident in non-affected eyes. We investigated whether alterations of the retinal vasculature are linked to the intrathecal immunity and whether they allow prognostication of the future disease course.Material and methodsThis study includes two different patient cohorts recruited at a tertiary German academic multiple sclerosis center between 2018 and 2020 and a cohort of 40 healthy controls. A total of 90 patients with RRMS undergoing lumbar puncture and OCT-A analysis were enrolled into a cross-sectional cohort study to search for associations between the retinal vasculature and the intrathecal immune compartment. We recruited another 86 RRMS patients into a prospective observational cohort study who underwent clinical examination, OCT-A and cerebral magnetic resonance imaging at baseline and during annual follow-up visits to clarify whether alterations of the retinal vessels are linked to RRMS disease activity. Eyes with a history of optic neuritis were excluded from the analysis.ResultsRarefication of the superficial vascular complex occured during RRMS and was linked to higher frequencies of activated B cells and higher levels of the pro-inflammatory cytokines interferon-γ, tumor necrosis factor α and interleukin-17 in the cerebrospinal fluid. During a median follow-up of 23 (interquartile range 14 - 25) months, vessel loss within the superficial (hazard ratio [HR] 1.6 for a 1%-point decrease in vessel density, p=0.01) and deep vascular complex (HR 1.6 for a 1%-point decrease, p=0.05) was associated with future disability worsening.DiscussionOptic neuritis independent rarefication of the retinal vasculature might be linked to neuroinflammatory processes during RRMS and might predict a worse disease course. Thus, OCT-A might be a novel biomarker to monitor disease activity and predict future disability.

Background: Multiple sclerosis (MS) is a chronic neuroinflammatory disease affecting about 2.8 million people worldwide. Disease course after the most common diagnoses of relapsing-remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS) is highly variable and cannot be reliably predicted. This impairs early personalized treatment decisions. Objectives: The main objective of this study was to algorithmically support clinical decision-making regarding the options of early platform medication or no immediate treatment of patients with early RRMS and CIS. Design: Retrospective monocentric cohort study within the Data Integration for Future Medicine (DIFUTURE) Consortium. Methods: Multiple data sources of routine clinical, imaging and laboratory data derived from a large and deeply characterized cohort of patients with MS were integrated to conduct a retrospective study to create and internally validate a treatment decision score [Multiple Sclerosis Treatment Decision Score (MS-TDS)] through model-based random forests (RFs). The MS-TDS predicts the probability of no new or enlarging lesions in cerebral magnetic resonance images (cMRIs) between 6 and 24 months after the first cMRI. Results: Data from 65 predictors collected for 475 patients between 2008 and 2017 were included. No medication and platform medication were administered to 277 (58.3%) and 198 (41.7%) patients. The MS-TDS predicted individual outcomes with a cross-validated area under the receiver operating characteristics curve (AUROC) of 0.624. The respective RF prediction model provides patient-specific MS-TDS and probabilities of treatment success. The latter may increase by 5–20% for half of the patients if the treatment considered superior by the MS-TDS is used. Conclusion: Routine clinical data from multiple sources can be successfully integrated to build prediction models to support treatment decision-making. In this study, the resulting MS-TDS estimates individualized treatment success probabilities that can identify patients who benefit from early platform medication. External validation of the MS-TDS is required, and a prospective study is currently being conducted. In addition, the clinical relevance of the MS-TDS needs to be established.

Genetic mapping studies have identified thousands of associations between common variants and hundreds of human traits. Translating these associations into mechanisms is complicated by two factors: they fall into gene regulatory regions; and they are rarely mapped to one causal variant. One way around these limitations is to find groups of traits that share associations, using this genetic link to infer a biological connection. Here, we assess how many trait associations in the same locus are due to the same genetic variant, and thus shared; and if these shared associations are due to causal relationships between traits. We find that only a subset of traits share associations, with many due to causal relationships rather than pleiotropy. We therefore suggest that simply observing overlapping associations at a genetic locus is insufficient to infer causality; direct evidence of shared associations is required to support mechanistic hypotheses in genetic studies of complex traits.Christiane Gasperi et al. used a shared association mapping approach to identify pairs of immune cell traits and gene expression traits showing shared genetic associations. Using polygenic risk score analysis and Mendelian randomization approaches, they find that while many such shared associations indicate a causal relationship between traits, observation of overlapping genomic associations alone is not sufficient to infer causality.

Background Upon treatment with biopharmaceuticals, the immune system may produce anti-drug antibodies (ADA) that inhibit the therapy. Up to 40% of multiple sclerosis patients treated with interferon β (IFNβ) develop ADA, for which a genetic predisposition exists. Here, we present a genome-wide association study on ADA and predict the occurrence of antibodies in multiple sclerosis patients treated with different interferon β preparations. Methods We analyzed a large sample of 2757 genotyped and imputed patients from two cohorts (Sweden and Germany), split between a discovery and a replication dataset. Binding ADA (bADA) levels were measured by capture-ELISA, neutralizing ADA (nADA) titers using a bioassay. Genome-wide association analyses were conducted stratified by cohort and treatment preparation, followed by fixed-effects meta-analysis. Results Binding ADA levels and nADA titers were correlated and showed a significant heritability (47% and 50%, respectively). The risk factors differed strongly by treatment preparation: The top-associated and replicated variants for nADA presence were the HLA -associated variants rs77278603 in IFNβ-1a s.c. - (odds ratio (OR) = 3.55 (95% confidence interval = 2.81–4.48), p  = 2.1 × 10 −26 ) and rs28366299 in IFNβ-1b s.c. -treated patients (OR = 3.56 (2.69–4.72), p  = 6.6 × 10 −19 ). The rs77278603-correlated HLA haplotype DR15-DQ6 conferred risk specifically for IFNβ-1a s.c. (OR = 2.88 (2.29–3.61), p  = 7.4 × 10 −20 ) while DR3-DQ2 was protective (OR = 0.37 (0.27–0.52), p  = 3.7 × 10 −09 ). The haplotype DR4-DQ3 was the major risk haplotype for IFNβ-1b s.c. (OR = 7.35 (4.33–12.47), p  = 1.5 × 10 −13 ). These haplotypes exhibit large population-specific frequency differences. The best prediction models were achieved for ADA in IFNβ-1a s.c. -treated patients. Here, the prediction in the Swedish cohort showed AUC = 0.91 (0.85–0.95), sensitivity = 0.78, and specificity = 0.90; patients with the top 30% of genetic risk had, compared to patients in the bottom 30%, an OR = 73.9 (11.8–463.6, p  = 4.4 × 10 −6 ) of developing nADA. In the German cohort, the AUC of the same model was 0.83 (0.71–0.92), sensitivity = 0.80, specificity = 0.76, with an OR = 13.8 (3.0–63.3, p  = 7.5 × 10 −4 ). Conclusions We identified several HLA -associated genetic risk factors for ADA against interferon β, which were specific for treatment preparations and population backgrounds. Genetic prediction models could robustly identify patients at risk for developing ADA and might be used for personalized therapy recommendations and stratified ADA screening in clinical practice. These analyses serve as a roadmap for genetic characterizations of ADA against other biopharmaceutical compounds.

Multiple sclerosis (MS) is a chronic inflammatory neurological disease of the CNS that goes along with demyelination and neurodegeneration. It is probably caused by an autoimmune response against the CNS, which emerges from the interplay of genetic and environmental factors. Although major progress has been made in the treatment of MS, it is still the leading cause for acquired nontraumatic neurological disability in young adults. Several therapeutic agents have been approved for the treatment of relapsing-remitting MS (RRMS), aiming at the reduction of relapses and a delay in disability progression. Three therapeutic monoclonal antibodies targeting CD20-positive B cells (rituximab, ocrelizumab and ofatumumab) were investigated in MRI-based Phase II and Phase III trials in RRMS, providing consistent evidence for a disease-ameliorating effect of B cell depleting therapies in MS. Here, we discuss the role of B cells and review current and future therapeutic approaches to target B cells in MS.