Castleman disease (CD) is an inflammatory disorder characterized by lymphadenopathy with distinctive histologic features, yet its pathophysiology remains poorly understood. This delays diagnoses and limits treatments, leading to additional morbidity and mortality. We used single- cell and spatial transcriptomics to characterize lymph nodes from unicentric CD (UCD) compared with non-specific inflammatory lymphadenopathies. While hematopoietic cells showed few compositional or transcriptional differences, lymph node stromal cells exhibited marked alterations in UCD, most notably an increased abundance of vascular smooth muscle cells (VSMCs) and broadly increased stromal signaling activity. A generalized linear model distinguished histologically indeterminate lymph nodes resembling UCD from non-specific inflammation most accurately using stromal rather than hematopoietic cell composition. Immunohistochemical staining for the VSMC marker CD146 (Melanoma Cell Adhesion Molecule, MCAM) further discriminated UCD from other causes of lymphadenopathy. Together, these findings identify increased VSMC abundance as a hallmark of UCD and suggest that this stromal signature can be leveraged to improve pathologic diagnosis and patient stratification.
An immunosuppressive, macrophage-rich tumor microenvironment (TME) is a barrier to immunotherapy across many cancers including osteosarcoma, where immunotherapy has largely failed. cGAS-STING agonism has been explored to inflame such tumors, yet the mechanisms of STING-mediated TME remodeling remain poorly understood, especially in sarcomas. Using multi-modal single cell analysis, we show that systemic STING agonism in osteosarcoma triggers a myeloid-predominant inflammatory response and rapid tumor necrosis, followed by a T cell-mediated response, immunologic memory, and long-term cure in some models. Within two hours of treatment, STING agonism induces pro-inflammatory interferon programs in tumor-associated macrophages and monocytes, with additional contributions from endothelial cells. Efficacy persists in the absence of tumor-intrinsic STING or IFNAR, confirming that the therapeutic axis resides within the host TME rather than the tumor cell compartment. While cGAS-STING is frequently repressed in human osteosarcoma models of aggressive disease, a STING activation gene signature predicts survival in newly diagnosed patients, suggesting that this pathway is engaged during tumor progression. Together, these data identify an opportunity to exploit the myeloid compartment of osteosarcoma with STING pathway therapies, charting a path forward for engaging the TME to secure long term cure in an aggressive malignancy still treated with highly toxic chemotherapy.
BACKGROUND. Despite the availability of effective vaccines, pneumococcal disease remains a major global health concern. Pneumococcal conjugate vaccines (PCVs) have progressively increased in valency, a change associated with reduced antibody titers against individual polysaccharide antigens. Whether increasing vaccine valency affects B cell responses through antigenic competition remains incompletely understood. We investigated pneumococcal polysaccharide-specific B cell responses in peripheral blood and vaccine draining lymph nodes following vaccination with PCV13. METHODS. Healthy adults ( n = 5) received PCV13. Peripheral blood and lymph node fine needle aspirations (FNA) were collected longitudinally at baseline and after vaccination. Pneumococcal polysaccharide-specific B cell responses, polysaccharide-specific antibody responses and opsonophagocytic activity were analyzed in peripheral blood and draining lymph nodes. RESULTS. Antigen-specific memory B cells in peripheral blood expanded rapidly and peaked 2 weeks after vaccination. In contrast, germinal center formation in lymph nodes was delayed, peaking at 4 weeks. Germinal center B cell responses were dominated by a limited number of polysaccharide specificities, whereas the expansion of memory B cells in peripheral blood was more evenly distributed across specificities. Polysaccharide-specific antibodies followed similar dynamics in plasma and FNA supernatant. CONCLUSION. Adult immune responses to PCV are characterized by robust extrafollicular memory B cell expansion and delayed germinal center responses. The restricted specificity of germinal center B cells provides evidence for antigenic competition during germinal center formation, with potential implications for the design and immunogenicity of multivalent vaccines. TRIAL REGISTRATION. EU CT number 2022-501519-15-00. FUNDING. LUMC PhD Fellowship, ZonMW Vidi and ZonMW Clinical Fellowship.
TGF-β is a central driver of kidney fibrosis, a common pathological hallmark of chronic kidney disease (CKD). Initiation of TGF-β signaling requires not only its synthesis but also the conversion of latent TGF-β to its bioactive form. However, the mechanisms governing TGF-β activation in the kidney and their contribution to kidney fibrosis remain poorly understood. Glycoprotein A repetitions predominant (GARP) anchors latent TGF-β on the cell surface and facilitates its bioactive release. Here, we show that GARP-mediated TGF-β activation promotes kidney fibrosis. GARP was upregulated in both human and mouse CKD kidneys, predominantly in fibroblasts, and was induced by TNF in an NF-κB–dependent fashion. In multiple mouse models of kidney fibrosis, either global or fibroblast-specific deletion of GARP markedly reduced fibrosis. Mechanistically, GARP enables sustained production of active TGF-β, thereby amplifying fibroblast stimulation. Deletion of GARP in kidney fibroblasts lowered active TGF-β levels and attenuated fibroblast activation, whereas GARP overexpression enhanced TGF-β signaling. Notably, tamoxifen-induced deletion of GARP after fibrosis onset attenuated kidney fibrosis. Together, our findings identify GARP-mediated release of active TGF-β as a critical step in sustaining fibroblast activation during kidney fibrosis and highlight GARP as a promising therapeutic target for CKD.
Tregs play an essential role in immune tolerance, and Treg-promoting therapies are in development for the treatment of many inflammatory disorders. IL-2–based therapies increase Treg frequency, but little is known about impacts on Treg heterogeneity and function. We extended analyses of an IL-2 mutein (MK-6194) single ascending dose trial in healthy human participants by comprehensively defining Treg subsets and gene expression changes in vitro and in vivo. We found highly specific and dose-dependent activation and expansion of Tregs in clinical and preclinical studies. Following a single subcutaneous dose in humans, thymus-derived Tregs were selectively activated and expanded, while peripherally induced Tregs were unaffected. Expanded Tregs had increased expression of genes and proteins consistent with activation, suppressor function, and homing to nonlymphoid tissue, as well as increased transendocytotic activity, as measured by CTLA-4–dependent capture of CD80 and CD86 from non-Tregs. These results shed light onto underlying mechanisms by which Treg-targeted therapy may promote immune tolerance.
