Biology subjects

Rosenfeld, A.

Publications and source records attributed to Rosenfeld, A..

3 recordsLinked to original sources

bioRxiv2025

SELECTION OF ANTI-NUCLEAR ANTIGEN (ANA) REACTIVE B CELLS IN SYSTEMIC LUPUS ERYTHEMATOSUS.

ObjectiveAutoreactive B cells that recognize nuclear antigens are normally present in healthy individuals and patients with systemic lupus erythematosus (SLE), yet their activation and the production of IgG autoantibodies is a hallmark of SLE. The selection process and regulation of these cells in patients with SLE has not been completely understood. To gain insights into tolerance checkpoints and the developmental trajectories of autoreactive clones, we studied the BCR sequences from thousands of anti-nuclear antigen binding (ANA)+ and ANA-B cells from patients with SLE. MethodsFrom a cohort of 13 patients with SLE, we identified and isolated ANA+ and ANA-B cells by flow cytometry using a method based on their binding to nuclear extracts. We sequenced B cell receptor (BCR) heavy chain variable regions and investigated the features of the IgH repertoire of ANA+ and ANA-B cells from naive, memory and age-associated B cells (ABCs), and from total plasmablasts. ResultsThe frequency of ANA+ B cells was similar in ABCs and naive B cells and higher in both than in memory B cells. We observed preferential usage of some VH (IGHV1-18, IGHV3-21, IGHV3-23|3-23D, IGHV4-34, IGHV4-39 and IGHV4-59) and VJ genes (IGHJ4 and IGHJ6) in B cells from these patients. ANA+ naive and ANA+ ABCs used different gene segments and have longer CDR3 sequences than ANA+ memory B cells and ANA-subsets. ANA+ ABCs and memory B cells have a lower frequency of somatic hypermutation (SHM) and less activation induced deaminase (AID) targeting to WRC hotspots compared with their ANA-counterparts. Patients with active disease have a lower frequency of SHM in ANA+ ABCs and memory B cells and in ANA-ABCs. ConclusionCompared to memory B cells, ABCs are enriched in autoreactivity. Our results suggest that there is an immune checkpoint that restricts the differentiation of ANA+ naive B cells into memory B cells and that ANA+ ABCs originate from ANA+ naive B cells. Lower frequencies of SHM in antigen experienced ANA+ B cells, and particularly ANA+ ABCs, suggest that these cells might be generated through an extrafollicular (EF) pathway, and that in patients with active SLE there is more EF activation.

immunology↗

bioRxiv2023

Neutron capture enhances dose and reduces cancer cell viability in and out of beam during helium and carbon ion therapy.

PurposeNeutron Capture Enhanced Particle Therapy (NCEPT) is a proposed augmentation of charged particle therapy which exploits thermal neutrons generated internally, within the treatment volume via nuclear fragmentation, to deliver a biochemically targeted radiation dose to cancer cells. This work is the first experimental demonstration of NCEPT, performed using both carbon and helium ion beams with two different targeted neutron capture agents (NCAs). Materials and MethodsHuman glioblastoma cells (T98G) were irradiated by carbon and helium ion beams in the presence of NCAs, [10B]-BPA and [157Gd]-DOTA-TPP. Cells were positioned within a PMMA phantom either laterally adjacent to, or within, a 100x100x60 mm spread out Bragg peak (SOBP). The impact of NCAs and location relative to the SOBP on the cells was measured by cell growth and survival assays in six independent experiments. Neutron fluence within the phantom was characterised by quantifying the neutron activation of gold foil. ResultsCells placed inside the treatment volume reached 10% survival by 2 Gy of C or 2-3 Gy of He in the presence of NCAs compared to 5 Gy of C and 7 Gy of He with no NCA. Cells placed adjacent to the treatment volume showed a dose-dependent decrease in cell growth when treated with NCAs, reaching 10% survival by 6 Gy of C or He (to the treatment volume), compared to a no detectable effect on cells without NCA. The mean thermal neutron fluence at the centre of the SOBP was approximately 2.2x109 n/cm2/Gy(RBE) for the carbon beam and 5.8x109 n/cm2/Gy(RBE) for the helium beam and gradually decreased in all directions. ConclusionsThe addition of NCAs to cancer cells during C and He beam irradiation has a measurable impact on cell survival and growth in-vitro. Through the capture of internally generated neutrons, NCEPT introduces the concept of a biochemically targeted radiation dose to charged particle therapy. NCEPT enables the established pharmaceuticals and concepts of neutron capture therapy to be applied to a wider range of deeply situated and diffuse tumours, by targeting this dose to micro-infiltrates and cells outside of defined treatment regions. These results also demonstrate the potential for NCEPT to provide an increased dose to tumour tissue within the treatment volume, with a reduction in radiation doses to off target tissue.

biophysics↗

bioRxiv2018

Role of RIG-I-like receptors in innate immune sensing of Coxsackievirus B3 and encephalomyocarditis virus in murine macrophages and fibroblasts

Viral infections are sensed by pattern recognition receptors that trigger an innate immune response through the expression of interferons (IFNs) and other cytokines. Most RNA viruses are sensed by the RIG-I like receptors (RLR)s. The contributions of these receptors to sensing viruses of the Picornaviridae family were investigated. Encephalomyocarditis virus (EMCV) and Coxsackievirus B3 (CVB3), picornaviruses of the Cardiovirus and Enterovirus genera, are detected by both MDA5 and RIG-I in bone marrow derived macrophages. In macrophages from wild type mice, type I IFN is produced early after infection; IFN{beta} synthesis is reduced in the absence of each sensor, while IFN production is reduced in the absence of MDA5. EMCV and CVB3 do not replicate in murine macrophages, and their detection is different in murine embryonic fibroblasts (MEFs), in which the viruses replicate to high titers. In MEFs RIG-I was essential for the expression of type I IFNs but contributes to increased yields of CVB3, while MDA5 inhibited CVB3 replication but in an IFN independent manner. These observations demonstrate that innate sensing of similar viruses by RLRs depends upon the cell type.\n\nImportanceEnteroviruses such as Coxsackieviruses are the most common human respiratory pathogens. The hosts innate immune response, in particular that modulated by the production of type I and III interferons, is thought to restrict picornavirus infection. Two cytoplasmic proteins, MDA5 and RIG-I, are critical for initiating the early innate immune response against these viruses. Mutations within MDA5 encoding gene have been associated with the development of severe enterovirus associated respiratory illnesses in healthy children. To further understand how the innate immune response dependent upon MDA5 and Rig-I is initiated during picornavirus infection, macrophages from mice lacking MDA5 or RIG-I were infected with Coxsackievirus B3 (CVB3) and a related animal virus. RIG-I is essential for type I IFN production during CVB3 infection; when MDA5 is present, viral titers are reduced by an IFN-independent pathway. These observations demonstrate that innate sensing of viruses by MDA5 and RIG-I depends upon the cell type.

microbiology↗