Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. The therapeutic landscape for MS has evolved significantly since the 1990s, with the development of more than 20 different disease-modifying therapies (DMTs). These therapies effectively manage relapses and inflammation, but most have failed to meaningfully prevent disease progression. While classically understood as a T cell-mediated condition, the most effective DMTs in slowing progression also target B cells. Novel classes of MS therapies in development, including anti-CD40L monoclonal antibodies, CD19 chimeric antigen receptor (CAR) T cells, and Bruton’s tyrosine kinase (BTK) inhibitors show greater capacity to target and eliminate B cells in the brain/CNS, as well as impacting T-cell and innate immune compartments. These approaches may help tackle the disease at its immunopathological core, addressing both peripheral and central immune responses that drive MS progression. Another emerging therapeutic strategy is to use bispecific antibodies, which have the potential for dual-targeting various disease aspects such as immune activation and neurodegeneration. As such, the next generation of MS therapies may be the first to reduce both inflammatory demyelination and disease progression in a clinically meaningful way. Their ability to target specific immune cell populations while minimizing broad immune suppression could also lead to better safety profiles. Here, we explore the biological rationale, advantages, limitations, and clinical progress of these emerging immunotherapies for relapsing–remitting and progressive forms of MS.

Multiple sclerosis (MS) is the most common autoimmune demyelinating disease of the central nervous system (CNS), consisting of heterogeneous clinical courses varying from relapsing-remitting MS (RRMS), in which disability is linked to bouts of inflammation, to progressive disease such as primary progressive MS (PPMS) and secondary progressive MS (SPMS), in which neurological disability is thought to be linked to neurodegeneration. As a result, successful therapeutics for progressive MS likely need to have both anti-inflammatory and direct neuroprotective properties. The modulation of sphingosine-1-phosphate (S1P) receptors has been implicated in neuroprotection in preclinical animal models. Siponimod/BAF312, the first oral treatment approved for SPMS, may have direct neuroprotective benefits mediated by its activity as a selective (S1P receptor 1) S1P1 and (S1P receptor 5) S1P5 modulator. We showed that S1P1 was mainly present in cortical neurons in lesioned areas of the MS brain. To gain a better understanding of the neuroprotective effects of siponimod in MS, we used both rat neurons and human-induced pluripotent stem cell (iPSC)-derived neurons treated with the neuroinflammatory cytokine tumor necrosis factor-alpha (TNF-α). Cell survival/apoptotic assays using flow cytometry and IncuCyte live cell analyses showed that siponimod decreased TNF-α induced neuronal cell apoptosis in both rat and human iPSCs. Importantly, a transcriptomic analysis revealed that mitochondrial oxidative phosphorylation, NFκB and cytokine signaling pathways contributed to siponimod’s neuroprotective effects. Our data suggest that the neuroprotection of siponimod/BAF312 likely involves the relief of oxidative stress in neuronal cells. Further studies are needed to explore the molecular mechanisms of such interactions to determine the relationship between mitochondrial dysfunction and neuroinflammation/neurodegeneration.

The soluble variant of the ectopeptidase CD13 (sCD13), released from the cell surface by matrix metalloproteinase 14 (MMP14), is a potent pro-inflammatory mediator, displaying chemotactic, angiogenic, and arthritogenic properties through bradykinin receptor B1 (B1R). We revealed a link between sCD13 and amplified neutrophil-mediated inflammatory responses in SARS-CoV-2 infection. sCD13 was markedly elevated in patients with COVID-19 and correlated with disease severity and variants, ethnicity, inflammation markers, and neutrophil extracellular trap formation (NETosis). Neutrophils treated with sCD13 showed heightened NETosis and chemotaxis, which were inhibited by sCD13 receptor blockade. Meanwhile sCD13 did not induce platelet aggregation. Single-cell analysis of COVID-19 lungs revealed coexpression of CD13 and MMP14 by various cell types, and higher CD13 expression compared with controls. Neutrophils with high CD13 mRNA were enriched for genes associated with immaturity, though CD13 protein expression was lower. Histological examination of COVID-19 lungs revealed CD13-positive leukocytes trapped in vessels with fibrin thrombi. Flow cytometry verified the presence of B1R and a second sCD13 receptor, protease-activated receptor 4, on monocytes and neutrophils. These findings identify sCD13 as a potential instigator of COVID-19–associated NETosis, potentiating vascular stress and thromboembolic complications. The potent pro-inflammatory effects of sCD13 may contribute to severe COVID-19, suggesting that sCD13 and its receptors might be therapeutic targets.

BACKGROUND: Individuals with autoimmune diseases (ADs) on immunosuppressants often have suboptimal responses to COVID-19 vaccines. We evaluated the efficacy and safety of additional COVID-19 vaccines in those treated with mycophenolate mofetil/mycophenolic acid (MMF/MPA), methotrexate (MTX), and B cell–depleting therapy (BCDT), including the impact of withholding MMF/MPA and MTX. METHODS: In this open-label, multicenter, randomized trial, 22 participants taking MMF/MPA, 26 taking MTX, and 93 treated with BCDT who had suboptimal antibody responses to initial COVID-19 vaccines (2 doses of BNT162b2 or mRNA-1273 or 1 dose of AD26.COV2.S) received an additional homologous vaccine. Participants taking MMF/MPA and MTX were randomized (1:1) to continue or withhold treatment around vaccination. The primary outcome was the change in anti–Wuhan-Hu-1 receptor-binding domain (RBD) concentrations at 4 weeks after additional vaccination. Secondary outcomes included adverse events, COVID-19, and AD activity through 48 weeks. RESULTS: Additional vaccination increased anti-RBD concentrations in participants taking MMF/MPA and MTX, irrespective of immunosuppressant withholding. BCDT-treated participants also demonstrated increased anti-RBD concentrations, albeit lower than MMF/MPA- and MTX-treated cohorts. COVID-19 occurred in 33% of participants; infections were predominantly mild and included only 3 nonfatal hospitalizations. Additional vaccination was well tolerated, with low frequencies of severe disease flares and adverse events. CONCLUSION: Additional COVID-19 vaccination is effective and safe in individuals with ADs treated with immunosuppressants, regardless of whether MMF/MPA or MTX is withheld. TRIAL REGISTRATION: ClinicalTrials.gov (NCT05000216; registered August 6, 2021: https://clinicaltrials.gov/ct2/show/NCT05000216). FUNDING: The NIH/NIAID supported the study through the Autoimmunity Centers of Excellence and the Intramural Research Program

Disease-modifying therapies (DMT)s) for relapsing-remitting multiple sclerosis (RRMS) act through distinct immunological mechanisms, yet the within-patient molecular response programs associated with these therapies remain incompletely defined. Here, we reanalyzed publicly available peripheral blood mononuclear cell (PBMC) miRNA microarray data (GSE230064) using a longitudinal, robustness-focused framework to compare therapy-associated miRNA response patterns following cladribine versus ocrelizumab treatment. Baseline (t0) and 6-month post-treatment (t1) samples were paired within individuals and technical replicates consolidated prior to analysis, yielding a final paired cohort of four cladribine-treated and six ocrelizumab-treated patients. Within each treatment arm, we quantified per-patient Δ-miRNA (t1 − t0) values and prioritized therapy-associated response features using a multi-evidence framework integrating effect direction, magnitude, directional consistency across individuals, and leave-one-out sensitivity. Cladribine treatment was associated with a highly coordinated, directionally concordant upregulation of five miRNAs including hsa-miR-27a-3p, hsa-miR-27b-3p, hsa-miR-503-5p, hsa-miR-148a-3p, and hsa-miR-26a-5p, all exhibiting 100% directional stability across patients and mean Δ-expression values ranging from +0.77 to +1.38. These miRNAs target pathways relevant to MS pathophysiology, including Th17/Treg balance, Wnt-β-catenin signaling, macrophage polarization, and epigenetic immune regulation. In contrast, ocrelizumab elicited a more selective response pattern, with five miRNAs including hsa-miR-100-5p, hsa-miR-410-3p, hsa-miR-432-5p, hsa-miR-296-5p, and hsa-miR-485-3p showing moderate directional stability (83%) and greater inter-individual heterogeneity, consistent with the more targeted mechanism of CD20+ B-cell depletion. Notably, the two treatment-associated signatures were non-overlapping, with hsa-miR-27b-3p representing the only miRNA shared with prior cross-sectional analyses of this dataset. The identified ocrelizumab-associated miRNAs implicate pathways including mTOR/IGF1R signaling, NF-κB regulation, RNA editing, and mitochondrial biogenesis, several of which are dysregulated in progressive MS. Together, these findings demonstrate that cladribine and ocrelizumab induce distinct, treatment-specific miRNA response architectures that reflect their divergent immunological mechanisms. This work establishes a stability-aware analytic template for extracting reproducible longitudinal miRNA signals from small paired RRMS cohorts and provides a ranked set of biologically plausible candidate miRNAs for prospective validation and mechanistic investigation.

Background: Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection caused by the JC virus and often fatal. Natalizumab is a highly effective therapy for multiple sclerosis (MS) but is linked to a high incidence of PML. The current metrics used to stratify MS patients at risk for PML are incomplete, leading some patients to prematurely discontinue an effective treatment and others to develop PML despite perceived low risk.Objective: We sought to develop a combination of cell-based assays using peripheral blood which can be used to provide a more comprehensive assessment of immune system function and complement existing PML risk metrics.Methods: Our assays measure general and JCV specific responses in CD4⁺ and CD8⁺ T cells following antigen stimulation. We examined responses in systemic lupus erythematosus (SLE) and MS patients with and without PML. Our cytotoxicity index (CTI) measures expression of IFNγ and the degranulation marker CD107a on CD8⁺ T cells, while our OX40 immunity index (OII) measures CD4⁺ T cell activation, as determined by OX40 and CD25 co-expression.Results and conclusion: We find that the combined metrics can be used to assess JCV immunocompetence, which can distinguish patients with and without PML, and could be used to predict and monitor PML patients from diagnosis onward to facilitate timely intervention.