Matthew F. Krummel

Germinal centers (GCs) form as confined clusters of motile cells within individual lymphoid follicles. The role of confinement in GC B cell evolutionary events is unknown. Here, using mice with reduced GC confinement because of deficiency in Gα13-dependent G-protein-coupled receptor signaling, we observed GC–GC trafficking in confinement-defective lymph nodes (LNs). In multicolor clonal lineage tracing mice, de-confined GCs minimally diversified their color palettes with respect to one another. Spatial B cell receptor sequencing revealed greater clonal crossover between neighboring GCs in the setting of dispersal. The total GC B cell repertoire of LNs with inter-GC exchange also decreased in overall diversity because of increased skewing toward top clones. As an outcome, LNs with de-confined GCs more strongly favored clones responding to accessible epitopes while losing clones binding to other portions of antigen. Together, our findings suggest that confinement supports antibody breadth by moderating the spread of dominant clones and preserving unique trajectories in individual GC responses.

Peer review serves as the cornerstone of scientific quality control. Yet, the current journal-centric system is hindered by long timelines, high publication costs, inconsistent review quality, systemic biases, and editorial gatekeeping. Notably, the system relies on misaligned measures of impact that are tethered to journal branding and conflate scientific rigor ( Quality ) with perceived significance ( Impact ). Here, we report findings from the Discovery Stack Pilot Study, which tested a scientist-designed, journal-independent peer review model. The Discovery Stack model integrates in-line reviewer comments to promote constructive feedback and separately evaluates scientific Quality and Impact using defined criteria. To examine feasibility and effectiveness, manuscripts were reviewed in parallel with traditional journal review. A total of 162 reviews were completed, and survey data from 86 participants were analyzed. The results showed that reviewers effectively evaluated Quality and Impact as separate dimensions, with Quality scores being more consistent across reviewers than Impact scores. Participants strongly supported the core elements of the Discovery Stack model and expressed enthusiasm for its broader adoption to enhance transparency, efficiency, and value in peer review. Future studies will explore integrating this model into a digital platform for reviewing and curating scientific discoveries to improve the production and dissemination of high-quality research.

A cell’s proteome is assumed to reflect its transcriptional and translational activity. Macrophages regularly acquire xenobiotic material from neighboring cells, which is thought to result in degradation of the material. However, increasing lines of evidence suggest that not all taken up material is degraded and other transfer-like processes also occur. Field standard technologies are unable to rigorously report on precisely how and by whom the macrophage protein repertoire is altered during these interactions, leaving unresolved the extent to which nondegradative processes contribute to altered phenotypes. Here, we leveraged chemical tools and proteomics to show that intact target cancer cell surface proteins are transferred to the macrophage cell surface at functionally impactful levels in a manner associated with live-cell uptake. Widespread acquisition of proteins during cell uptake reengineers the macrophage cell surface proteome and is a transcriptionally silent, cell-nonautonomous process with the potential to alter metabolic uptake.

Mouse models are frequently used to develop treatments for human cancer. However, the degree to which their tumor microenvironments (TMEs) are synonymously assembled is particularly poorly characterized. Through systematic immunoprofiling of 15 commonly used mouse models, we found that most murine TMEs recapitulate the composition of poorly infiltrated human tumors, extensively biased toward high macrophage densities. We discovered substantial species-specific biases of chemokine expression networks known to drive TMEs assembly, together with discoordinated frequencies of T and myeloid cell subtypes. Even with variable alignment, conserved cell-type-specific gene expression programs emerged across species and cohorts. Dissecting the coordinated T cell–myeloid gene expression programs revealed a conserved axis between interferon-responsive myeloid states and ongoing T cell cytotoxicity that transcends tissue of origin and predicts clinical outcome. Collectively, this work provides a practical atlas outlining both the hazards and opportunities of using mice to model human cancer.

An effective immune system must sample and develop healthy self-identity to prevent autoimmunity and to discern pathogenic insults ^1–3 . Self-proteins are presented to T cells in the thymus during immune cell development ^2,3 and must be presented throughout the body to maintain regulatory T cell populations ^4–6 and to provide tonic signals to sustain conventional T cells over time ^7–9 . Observations of continuous apoptosis in some organs together with the ingestion of that material by myeloid populations has led to a conventional understanding of ongoing cell death as a major source of self-antigens ¹⁰ . Here we used a series of companion imaging and vesicular labelling technologies to reveal an alternative process undertaken by macrophages that results in non-destructive, direct sampling of living cells. This process requires cell–cell contact, does not require caspase activation and occurs via trogocytosis-like stretching of the target cell into the macrophage, which leads to the generation of submicrometre-sized vesicles that contain cytoplasm. Using a high-dimensional flow-based method for labelling vesicles, we demonstrate that live-sampled material is distinctly processed and is poorly subjected to fusion with lysosomes. The material also produces differential effects on the presentation of antigen to CD4 T cells compared with CD8 T cells. Disruption of this trafficking by redirecting antigen to the lysosome significantly reduced the associated macrophage-mediated priming of CD8 T cells. These results demonstrate an important and substantial sampling of living cells by the immune system, with clear consequences for maintaining the border of immunity.

Fibroblasts play critical roles in regulating cellular relationships during tissue homeostasis, immunity, and tumor biology at multiple sites. However, tools to perturb fibroblasts at just one site in vivo are limited, restricting our understanding of how these cellular relationships act locally. We optimized local gene editing of fibroblasts in mouse tumor models to investigate how fibroblast perturbations affect the tumor microenvironment (TME). By knocking out receptors Osmr, Tgfbr2, or Il1r1 on cancer-associated fibroblasts (CAFs), we uncover that TGFBR2 signaling loss induces the emergence of a new Col18a1hi CAF cell state that is associated with worse survival in pancreatic cancer patients. Combinatorial gene KOs in CAFs reveals a circuit where these Col18a1hi CAFs reshape the TME by recruiting Siglec-Fhi neutrophils via Cxcl5 expression, and where this Col18a1hi CAF cell state is dependent on TNFR1 and canonical Wnt signaling. Together, a fast, affordable, and modular engineering method is demonstrated, allowing discovery of modified fibroblast identities and local intercellular relationships in the TME.

Supplementary Figures, Table, Supplementary Tables

α-Fetoprotein (AFP) is expressed by stem-like and poor outcome hepatocellular cancer tumors and is a clinical tumor biomarker. AFP has been demonstrated to inhibit dendritic cell (DC) differentiation and maturation and to block oxidative phosphorylation. To identify the critical metabolic pathways leading to human DC functional suppression, here, we used two recently described single-cell profiling methods, scMEP (single-cell metabolic profiling) and SCENITH (single-cell energetic metabolism by profiling translation inhibition). Glycolytic capacity and glucose dependence of DCs were significantly increased by tumor-derived, but not normal cord blood–derived, AFP, leading to increased glucose uptake and lactate secretion. Key molecules in the electron transport chain in particular were regulated by tumor-derived AFP. These metabolic changes occurred at mRNA and protein levels, with negative impact on DC stimulatory capacity. Tumor-derived AFP bound significantly more polyunsaturated fatty acids (PUFA) than cord blood–derived AFP. PUFAs bound to AFP increased metabolic skewing and promoted DC functional suppression. PUFAs inhibited DC differentiation in vitro, and ω-6 PUFAs conferred potent immunoregulation when bound to tumor-derived AFP. Together, these findings provide mechanistic insights into how AFP antagonizes the innate immune response to limit antitumor immunity.Significance:α-Fetoprotein (AFP) is a secreted tumor protein and biomarker with impact on immunity. Fatty acid–bound AFP promotes immune suppression by skewing human dendritic cell metabolism toward glycolysis and reduced immune stimulation.

Elimination of tumors is typically dependent on T cells, which require prior or ongoing activation signals. These dependencies form the basis for our understanding of “tumor‐reactive immunity” and for the successes of immunotherapies, particularly immune checkpoint blockades. Over the years, tremendous work has been done towards understanding the biology of this reactive immunity and early investigation identified dendritic cells (DC) as key contributors. Recent advances have shed more light on dendritic cell heterogeneity in tumors, revealing specialized roles for each subtype. In addition, the network of cellular interactions surrounding DCs has grown as additional cell types have been revealed to variously influence how the immune system can become most effective at eliminating malignancies. Greater understanding of intratumoral DC biology has empowered investigators to engineer dendritic cell vaccines and consider other approaches to augment this component of reactive immunity, towards the generation of anti‐tumor immune responses de novo . In this review, we will discuss the state of the field, recent advances and suggest what the near future of scientific inquiry could entail.