B cell depletion with anti-CD20 promotes neuroprotection in a BAFF-dependent manner in mice and humans

Follicle on the Roof: Tertiary Lymphoid Structures in Central Nervous System Autoimmunity

Leptomeningeal tertiary lymphoid structures (TLS) have emerged as a relatively common pathological feature of autoimmune disease, including multiple sclerosis (MS) and particularly in people with progressive and nonremitting MS. These ectopic lymphoid aggregates, observed in the leptomeninges adjacent to so-called "Type 3" sub-pial cortical lesions, are associated with more severe gray matter damage and worse clinical outcomes. Mouse models of MS that recapitulate TLS formation in the central nervous system (CNS) have provided critical insights into the mechanisms driving their development and maintenance. In these models of experimental autoimmune encephalomyelitis (EAE) initiation of TLS is facilitated by Th17 cells, which promote chronic inflammation via cytokines such as IL-17 and GM-CSF. The cell surface expression of lymphotoxin-α and lymphotoxin-β heterotrimers (LTαβ) on lymphocytes, including Th17 cells, elaborates the organization of ectopic lymphoid tissues via LTβR signaling on radio-resistant stromal cells and resident fibroblasts. Ultimately a pro-inflammatory environment characterized by cytokines such as IL-17 and GM-CSF promotes the recruitment of neutrophils which produce proteases and chemokines that sustain a pro-inflammatory milieu. Emerging EAE data suggest that disrupting TLS organization or targeting key pathways involved in their maintenance could represent promising strategies for modulating chronic CNS inflammation in MS. Understanding the cellular and molecular mechanisms regulating TLS dynamics is therefore critical for the development of therapies aimed at halting or reversing nonremitting MS disease.

Gasdermin-D Genetic Knockout Reduces Inflammasome-Induced Disruption of the Gut-Brain Axis After Traumatic Brain Injury

Traumatic brain injury (TBI) pathology is significantly mediated by an inflammatory response involving inflammasome activation, resulting in the release of interleukin (IL)-1β and pyroptotic cell death through gasdermin-D (GSDMD) cleavage. Inflammasome components are transported through extracellular vesicles (EVs) to mediate systemic inflammation in peripheral organs, including the gut. The purpose of this study was to determine the protective effect of GSDMD knockout (KO) on TBI-induced inflammasome activation, EV signaling, and gut function. GSDMD-KO and C57BL6 (WT) mice were subjected to the controlled cortical impact model of TBI. Cytokine expression was assessed with electrochemiluminescent immunoassay and immunoblotting of the cerebral cortex and gut. EVs were examined for pathology-associated markers using flow cytometry, and gut permeability was determined. GSDMD-KO attenuated IL-1β and IL-6 expression in the cerebral cortex and reduced IL-1β and IL-18 in the gut 3 days post-injury. GSDMD-KO mice had decreased neuronal- and gut-derived EVs compared to WT mice post-TBI. GSDMD-KO EVs also had decreased IL-1β and different surface marker expression post-TBI. GSDMD-KO mice had decreased gut permeability after TBI. These data demonstrate that GSDMD ablation improves post-TBI inflammation and gut pathology, suggesting that GSDMD may serve as a potential therapeutic target for the improvement of TBI-associated pathologies.

Profile and Usefulness of Serum Cytokines to Predict Prognosis in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

OBJECTIVES

To characterize the serum cytokine profile in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) at onset and during follow-up and assess their utility for predicting relapses and disability.

METHODS

This retrospective multicentric cohort study included patients aged 16 years and older meeting MOGAD 2023 criteria, with serum samples collected at baseline (≤3 months from disease onset) and follow-up (≥6 months from the baseline), and age-matched and time to sampling-matched patients with multiple sclerosis (MS). Eleven cytokines were assessed using the ELLA system. Data comparisons and statistical analyses between cytokine levels and clinical outcomes were performed.

RESULTS

Eighty-eight patients with MOGAD and 32 patients with MS were included. Patients with MOGAD showed higher IL6 (p = 0.036), IL8 (p = 0.012), and IL18 (p = 0.026) baseline levels compared with those with MS, in non-optic neuritis (ON) presentations. BAFF values increased over time, especially in patients with MOGAD treated with anti-CD20 (p = 0.002). Baseline BAFF, CXCL10, IL10, and IL8 levels correlated with disease severity at MOGAD onset (all p < 0.05). Finally, higher baseline BAFF levels predicted lower risk of relapses (hazard ratio 0.41 [0.19; 0.89], p = 0.024).

DISCUSSION

This study suggests a proinflammatory Th17-dominant profile in non-ON MOGAD patients, with a novel finding of a potential protective role of BAFF on relapses. These results shed new light on the pathogenesis of MOGAD, potentially guiding therapeutic decisions.

Multi-Omic characterization of the effects of Ocrelizumab in patients with relapsing-remitting multiple sclerosis

The study examined changes in the plasma proteome, metabolome, and lipidome of N = 14 patients with relapsing-remitting multiple sclerosis (RRMS) initiating treatment with ocrelizumab, assayed at baseline, 6 months, and 12 months. Analyses of >4000 circulating biomarkers identified depletion of B-cell associated proteins as the early effect observed following ocrelizumab (OCR) initiation, accompanied by the reduction in plasma abundance of cytokines and cytotoxic proteins, markers of neuronaxonal damage, and biologically active lipids including ceramides and lysophospholipids, at 6 months. B-cell depletion was accompanied by decreases in B-cell receptor and cytokine signaling but a pronounced increase in circulating plasma B-cell activating factor (BAFF). This was followed by an upregulation of a number of signaling and metabolic pathways at 12 months. Patients with higher baseline brain MRI lesion load demonstrated both higher levels of cytotoxic and structural proteins in plasma at baseline and more pronounced biomarker change trajectories over time. Digital cytometry identified a putative increase in myeloid cells and a pro-inflammatory subset of T-cells. Therapeutic effects of ocrelizumab extend beyond CD20-mediated B-cell lysis and implicate metabolic reprogramming, juxtaposing the early normalization of immune activation, cytokine signaling and metabolite and lipid turnover in periphery with changes in the dynamics of immune cell activation or composition. We identify BAFF increase following CD20 depletion as a tentative compensatory mechanism that contributes to the reconstitution of targeted B-cells, necessitating further research.

Targeting the adaptive immune continuum in atherosclerosis and post-MI injury

Atherosclerotic disease is a cholesterol-rich lipoprotein particle-driven disease resulting in the formation of atherosclerotic plaques in large and medium size arteries. Rupture or erosion of atherosclerotic plaques can trigger the formation of a thrombus causing the obstruction of the blood flow in the coronary artery and thereby leading to myocardial infarction (MI). Inflammation is a crucial pillar of the mechanisms leading to atherosclerosis and governing the cardiac repair post-MI. Dissecting the complex and sophisticated networks of the immune responses underlying the formation of atherosclerotic plaques and affecting the healing of the heart after MI will allow the designing of highly precise immunomodulatory therapies for these settings. Notably, MI also accelerates atherosclerosis via modulating the response of the immune system. Therefore, for the identification of effective and safe therapeutic targets, it is critical to consider the inflammatory continuum that interconnects the two pathologies and identify immunomodulatory strategies that confer a protective effect in both settings or at least, affect each pathology independently. Adaptive immunity, which consists of B and T lymphocytes, is a major regulator of atherosclerosis and post-MI cardiac repair. Here, we review and discuss the effect of potential adaptive immunity-targeting therapies, such as cell-depleting therapies, in atherosclerosis and post-MI cardiac injury.

B cells and the stressed brain: emerging evidence of neuroimmune interactions in the context of psychosocial stress and major depression

The immune system has emerged as a key regulator of central nervous system (CNS) function in health and in disease. Importantly, improved understanding of immune contributions to mood disorders has provided novel opportunities for the treatment of debilitating stress-related mental health conditions such as major depressive disorder (MDD). Yet, the impact to, and involvement of, B lymphocytes in the response to stress is not well-understood, leaving a fundamental gap in our knowledge underlying the immune theory of depression. Several emerging clinical and preclinical findings highlight pronounced consequences for B cells in stress and MDD and may indicate key roles for B cells in modulating mood. This review will describe the clinical and foundational observations implicating B cell-psychological stress interactions, discuss potential mechanisms by which B cells may impact brain function in the context of stress and mood disorders, describe research tools that support the investigation of their neurobiological impacts, and highlight remaining research questions. The goal here is for this discussion to illuminate both the scope and limitations of our current understanding regarding the role of B cells, stress, mood, and depression.

Un-BAFFling gray matter pathology in multiple sclerosis

BAFF mediates the neuroprotective effects of B cell depletion therapy in multiple sclerosis.