Biology subjects

Mytych, J. S.

Publications and source records attributed to Mytych, J. S..

3 recordsLinked to original sources

bioRxiv2026

Ocrelizumab Modulates Both B and T Cell Immune Capacities in Multiple Sclerosis

To understand the molecular and cellular mechanisms beyond B-cell depletion with the anti-CD20 monoclonal antibody ocrelizumab, we used comprehensive muti-modal flow cytometry and functional assays in a prospective longitudinal multiple sclerosis (MS) cohort. Ocrelizumab depleted the vast majority of B cells and showed selective effects on different B cells subsets. Analysis of residual/replenished B cells revealed relative enrichment of regulatory B cells like CD27+CD43+ B1 and CD24hiCD38hi transitional B cells, and reduction of CD27+ memory B cell subsets and CD19+IgD+CD27-naive B cells at early time points (1-3 month) and before subsequent infusions at 4-7 months, 11-14 months, and >18 months. CD20+ T cells and peripheral helper T-cells (Tph) were also reduced. RNA sequencing analysis showed B1 cells have significantly higher expression of LGALS1, KCNN4, ITGB1, and IL2RB. Compared to transitional B cells, B1 cells also displayed significantly higher expression of tissue homing molecules ITGAX (CD11c), S100A4, ITGB1, and CXCR3. IL10 signaling pathway is increased in these B cells. Ex vivo B cell functional assays indicated the residual/replenishing B cells were anergic following ocrelizumab, with increased IL10/TNF and IL10/IL6 ratios under BCR stimulation. Ocrelizumab treatment may create a self-reinforcing regulatory circuit: the reduction of Tph cells could alleviate suppression of regulatory B cells, which subsequently expand and further promote regulatory T cell networks via IL2RB, LGALS1, and an increased IL-10 signaling pathway.

immunology↗

bioRxiv2026

Longitudinal and stability-aware analysis reveals treatment-specific microRNA response signatures following immune-reconstitution and B-cell-targeted therapies in multiple sclerosis

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 reanalysed publicly available 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 4 cladribine-treated and 6 ocrelizumab-treated patients. Within each treatment arm, we quantified per-patient {Delta}-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 {Delta}-expression values ranging from +0.77 to +1.38. These miRNAs target pathways relevant to MS pathophysiology, including Th17/Treg balance, Wnt-{beta}-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-{kappa}B 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.

immunology↗

bioRxiv2023

Peptidoglycan from Bacillus anthracis Inhibits Human Macrophage Efferocytosis in Part by Reducing Cell Surface Expression of MERTK and TIM-3

Bacillus anthracis peptidoglycan (PGN) is a major component of the bacterial cell wall and a key pathogen-associated molecular pattern (PAMP) contributing to anthrax pathology, including organ dysfunction and coagulopathy. Increases in apoptotic lymphocytes are a late-stage feature of anthrax and sepsis, suggesting there is a defect in apoptotic clearance. Here, we tested the hypothesis that B. anthracis PGN inhibits the capacity of human monocyte-derived macrophages (M{Phi}) to efferocytose apoptotic cells. Exposure of CD163+CD206+ M{Phi} to PGN for 24h impaired efferocytosis in a manner dependent on human serum opsonins but independent of complement component C3. PGN treatment reduced cell surface expression of the pro-efferocytic signaling receptors MERTK, TYRO3, AXL, integrin V{beta}5, CD36 and TIM-3, whereas TIM-1, V{beta}3, CD300b, CD300f, STABILIN-1 and STABILIN-2 were unaffected. ADAM17 is a major membrane-bound protease implicated in mediating efferocytotic receptor cleavage. We found multiple ADAM17-mediated substrates increased in PGN-treated supernatant suggesting involvement of membrane-bound proteases. ADAM17 inhibitors TAPI-0 and Marimastat prevented TNF release, indicating effective protease inhibition, and modestly increased cell-surface levels of MerTK and TIM-3 but only partially restored efferocytic capacity by PGN-treated M{Phi}. We conclude that human serum factors are required for optimal recognition of PGN by human M{Phi} and that B. anthracis PGN inhibits efferocytosis in part by reducing cell surface expression of MERTK and TIM-3.

immunology↗