Multi-color Molecular Visualization of Signaling Proteins Reveals How C-Terminal Src Kinase Nanoclusters Regulate T Cell Receptor Activation

Elucidating the mechanisms that controlled T cell activation requires visualization of the spatial organization of multiple proteins on the submicron scale. Here, we use stoichiometrically accurate, multiplexed, single-molecule super-resolution microscopy (DNA-PAINT) to image the nanoscale spatial architecture of the primary inhibitor of the T cell signaling pathway, Csk, and two binding partners implicated in its membrane association, PAG and TRAF3. Combined with a newly developed co-clustering analysis framework, we find that Csk forms nanoscale clusters proximal to the plasma membrane that are lost post-stimulation and are re-recruited at later time points. Unexpectedly, these clusters do not co-localize with PAG at the membrane but instead provide a ready pool of monomers to downregulate signaling. By generating CRISPR-Cas9 knockout T cells, our data also identify that a major risk factor for autoimmune diseases, the protein tyrosine phosphatase non-receptor type 22 (PTPN22) locus, is essential for Csk nanocluster re-recruitment and for maintenance of the synaptic PAG population

3D Bayesian cluster analysis of super-resolution data reveals LAT recruitment to the T cell synapse

Single-molecule localisation microscopy (SMLM) allows the localisation of fluorophores with a precision of 10–30 nm, revealing the cell’s nanoscale architecture at the molecular level. Recently, SMLM has been extended to 3D, providing a unique insight into cellular machinery. Although cluster analysis techniques have been developed for 2D SMLM data sets, few have been applied to 3D. This lack of quantification tools can be explained by the relative novelty of imaging techniques such as interferometric photo-activated localisation microscopy (iPALM). Also, existing methods that could be extended to 3D SMLM are usually subject to user defined analysis parameters, which remains a major drawback. Here, we present a new open source cluster analysis method for 3D SMLM data, free of user definable parameters, relying on a model-based Bayesian approach which takes full account of the individual localisation precisions in all three dimensions. The accuracy and reliability of the method is validated using simulated data sets. This tool is then deployed on novel experimental data as a proof of concept, illustrating the recruitment of LAT to the T-cell immunological synapse in data acquired by iPALM providing ~10 nm isotropic resolution. Introduction

Galectin-9 binds IgM-BCR to regulate B cell signaling

The galectin family of secreted lectins are important regulators of immune cell function; however, their role in B cell responses is poorly understood. Here, the authors identify IgM-BCR as a ligand for galectin-9. In resting naive cells, they show that galectin-9 mediates a close association between IgM and CD22

The incidence and significance of anti-natalizumab antibodies - Results from AFFIRM and SENTINEL

Objective: To determine the incidence and clinical effects of antibodies that develop during treatment with natalizumab

Natalizumab plus interferon beta-1a for relapsing multiple sclerosis

.AbstractBackgroundInterferon beta is used to modify the course of relapsing multiple sclerosis. Despiteinterferon beta therapy, many patients have relapses. Natalizumab, an α4 integrinantagonist, appeared to be safe and effective alone and when added to interferonbeta-1a in preliminary studies.MethodsWe randomly assigned 1171 patients who, despite interferon beta-1a therapy, hadhad at least one relapse during the 12-month period before randomization to receivecontinued interferon beta-1a in combination with 300 mg of natalizumab (589patients) or placebo (582 patients) intravenously every 4 weeks for up to 116 weeks.The primary end points were the rate of clinical relapse at 1 year and the cumulativeprobability of disability progression sustained for 12 weeks, as measured by theExpanded Disability Status Scale, at 2 years.ResultsCombination therapy resulted in a 24 percent reduction in the relative risk of sustaineddisability progression (hazard ratio, 0.76; 95 percent confidence interval, 0.61to 0.96; P = 0.02). Kaplan–Meier estimates of the cumulative probability of progressionat two years were 23 percent with combination therapy and 29 percent withinterferon beta-1a alone. Combination therapy was associated with a lower annualizedrate of relapse over a two-year period than was interferon beta-1a alone (0.34vs. 0.75, P<0.001) and with fewer new or enlarging lesions on T2-weighted magneticresonance imaging (0.9 vs. 5.4, P<0.001). Adverse events associated with combinationtherapy were anxiety, pharyngitis, sinus congestion, and peripheral edema.Two cases of progressive multifocal leukoencephalopathy, one of which was fatal,were diagnosed in natalizumab-treated patients.ConclusionsNatalizumab added to interferon beta-1a was significantly more effective than interferonbeta-1a alone in patients with relapsing multiple sclerosis. Additional researchis needed to elucidate the benefits and risks of this combination treatment.(ClinicalTrials.gov number, NCT00030966.