The Shulman Lab

Antibody-mediated immune responses in mucosal tissues are critical for defending against pathogens while maintaining homeostasis with commensals. Nasal vaccination aims to induce local protection in the upper airway mucosa. Although B cell-driven immunity is well characterized in gut-associated lymphoid tissues such as Peyer's patches and mesenteric LNs, much less is known about analogous processes in the upper airways. Here, we show that B cell receptor (BCR) affinity and CCR6 regulate germinal center (GC) seeding and class-switch recombination (CSR) to IgA in nasal-associated lymphoid tissue (NALT) following nasal vaccination. B cells bearing low-affinity BCRs failed to upregulate CCR6 and did not support T follicular helper cell differentiation or seed GCs in the NALT. CCR6-deficient B cells were unable to migrate to the NALT subepithelial dome or undergo IgA CSR and seed GC effectively in response to nasal vaccination or commensal bacteria signals. Thus, effective targeting of B cell clones to induce CCR6 expression is essential for nasal vaccine design.

Tumor-infiltrating B cells have emerged in recent years as key markers of patient prognosis and responsiveness to immunotherapy. Recent technical advances, such as single-cell RNA sequencing and B cell receptor immune profiling, revealed diverse subsets and the immunoglobulin landscape of B cells located within human tumors. Secreted antibodies in solid tumors exhibit multiple effector functions, with the potential to significantly impact distinct immune responses, clinical outcomes, and patient survival. Nonetheless, a few studies examine the tumor reactivity and specificity of these immunoglobulins. Here we describe our current methodology for retrieving single B cells from human primary solid tumors for single-cell RNA sequencing followed by computational analysis to identify B cell subpopulations and immunoglobulin receptor repertoires. Furthermore, we provide a technique for evaluating and quantifying the tumor-binding capabilities of expressed antibodies. This approach holds promise for future immunotherapies and enhances our understanding of their potential clinical applications.

The establishment of long-lasting immunity against pathogens is facilitated by the germinal center (GC) reaction, during which B cells increase their antibody affinity and differentiate into antibody-secreting cells (ASC) and memory cells. These events involve modifications in chromatin packaging that orchestrate the profound restructuring of gene expression networks that determine cell fate. While several chromatin remodelers were implicated in lymphocyte functions, less is known about SMARCA5. Here, using ribosomal pull-down for analyzing translated genes in GC B cells, coupled with functional experiments in mice, we identified SMARCA5 as a key chromatin remodeler in B cells. While the naive B cell compartment remained unaffected following conditional depletion of Smarca5, effective proliferation during B cell activation, immunoglobulin class switching, and as a result GC formation and ASC differentiation were impaired. Single-cell multiomic sequencing analyses revealed that SMARCA5 is crucial for facilitating the transcriptional modifications and genomic accessibility of genes that support B cell activation and differentiation. These findings offer novel insights into the functions of SMARCA5, which can be targeted in various human pathologies.