Project description:We report that antibody-mediated CD22 blockage leads to an altered transcriptomic signature profile which, by further evaluating the affected genes, resembles a homeostatic phenotype.
Project description:Sequencing data related to the manuscript entitled, "CD22 blockade restores homeostatic microglial phagocytosis in the aging brain."
Project description:CD22 (Siglec-2) is a member of the Siglec family. It is an inhibitory co-receptor of the B-cell-receptor (BCR) and inhibits B–cell activation. Upon BCR stimulation ITIMs in the cytoplasmic tail of CD22 are phosphorylated. This triggers CD22 signalling pathways, which lead to a decreased calcium mobilization in the B cell and thus an inhibition of BCR signalling. Although some CD22 binding partners, such as the phosphatase SHP-1, have already been identified, we deciphered the CD22 interactome in more detail, to gain a deeper understanding of CD22 molecular mechanisms and signalling events after BCR activation. Stable isotope labelling of amino acids in cell culture (SILAC) in combination with mass spectrometry analysis enabled the identification of specific CD22 interaction partners in a quantitative proteomics approach. Hereby, several new CD22 associated proteins were identified that have not been linked to CD22 yet. One of those interacting proteins is cullin 3, an E3 ubiquitin ligase. It was revealed that cullin 3 is important for clathrin-dependent CD22 internalization after BCR stimulation and CD22 surface expression. Further analysis of B-cell specific cullin 3 deficient mice showed an important role of cullin 3 in B cell development. These mice have strongly reduced numbers of mature B cells in the periphery, which are characterized by increased CD22 expression and additionally by pre-activated and apoptotic phenotypes.
Project description:Germinal centres (GC) are specialized sites where B cells expand and diversify their antibody genes through somatic hypermutation. GC B-cells are routinely identified through distinct changes on their surface carbohydrates, known as glycans. One striking modification relates to the monosaccharide sialic acid. In mice, this change is mediated through downregulation of an enzyme called CMAH, which results in a GC-specific loss of preferred ligand for CD22, a member of the sialic acid-binding immunoglobulin-type lectins (Siglecs) and an inhibitory co-receptor of the B-cell antigen receptor (BCR). Here, we identified that glycan remodeling, mediated by downregulation of CMAH, is crucial for the GC B-cell response, and production of memory B-cells, plasma cells, and high affinity antibodies. We also demonstrated that the function of these altered glycans is dependent on CD22, highlighting that coordinated loss of preferred ligands acts to modulates the CD22 activity in the GC B-cells. Overall, our study reveals that intrinsic glycan remodeling functions to optimize the B-cell responses in the GC by controlling CD22.
Project description:Sequencing data related to the manuscript entitled, "CD22 blockade restores homeostatic microglial phagocytosis in the aging brain."
Project description:While therapies targeting CD19 by antibodies, CAR-T cells and T cell engagers have improved the response rates in B-cell malignancies; the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19-immunotoxin. Single-cell (sc) RNAseq showed increase in transcriptionally distinct CD19low populations in resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19low resistant cells. ATAC-seq showed decreased chromatin accessibility at promoters of both CD19 and CD22 in the resistant cell populations. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with B-ALL that relapsed after CD19 CAR-T targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19low resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both BTK and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.
Project description:While therapies targeting CD19 by antibodies, CAR-T cells and T cell engagers have improved the response rates in B-cell malignancies; the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19-immunotoxin. Single-cell (sc) RNAseq showed increase in transcriptionally distinct CD19low populations in resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19low resistant cells. ATAC-seq showed decreased chromatin accessibility at promoters of both CD19 and CD22 in the resistant cell populations. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with B-ALL that relapsed after CD19 CAR-T targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19low resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both BTK and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.
Project description:We did three sets of microarrays with three replicates each for a total of 9 arrays. Each array was run using pooled RNA from three animals. The three conditions were Normal tail skin (no intervention), Lymphedema tail skin(due to surgical lymphatic vessel blockage), and Surgical Sham control tail skin(surgical incision with no lymphatic vessel blockage). 15ug of test and reference (e17.5 mouse whole embryo) RNA was used for labeling.