Colony stimulating factor-1 receptor (CSF-1R) and its ligands CSF-1 and interleukin (IL)-34 have tumorigenic effects through both induction of suppressive macrophages, and survival/proliferation of tumor cells. In addition, the IL-34 tumorigenic effect can also be mediated by its other receptors, protein-tyrosine phosphatase zeta, Syndecan-1 (CD138) and triggering receptor expressed on myeloid cells 2. Small tyrosine kinase inhibitors are used to block CSF-1R signaling but lack specificity. Neutralizing anti-CSF-1 and/or IL-34 antibodies have been proposed, but their effects are limited. Thus, there is a need for a more specific and yet integrative approach.
A human mutated form of the extracellular portion of CSF-1R was in silico modelized to trap both IL-34 and CSF-1 with higher affinity than the wild-type CSF-1R by replacing the methionine residue at position 149 with a Lysine (M149K). The extracellular portion of the mutated CSF-1R M149K was dimerized using the immunoglobulin Fc sequence of a silenced human IgG1 (sCSF-1RM149K-Fc). Signaling through CSF-1R, survival of monocytes and differentiation of suppressive macrophages were analyzed using pleural mesothelioma patient's samples and mesothelioma/macrophage spheroids in vitro and in vivo in the presence of sCSF-1RM149K-Fc or sCSF-1R-Fc wild type control (sCSF-1RWT-Fc).
We defined that the D1 to D5 domains of the extracellular portion of CSF-1R were required for efficient binding to IL-34 and CSF-1. The mutein sCSF-1RM149K-Fc trapped with higher affinity than sCSF-1RWT-Fc both CSF-1 and IL-34 added in culture and naturally produced in mesothelioma pleural effusions. sCSF-1RM149K-Fc inhibited CSF-1R signaling, survival and differentiation of human suppressive macrophage in vitro and in vivo induced by pleural mesothelioma cells. Neutralization of IL-34 and CSF-1 by sCSF-1RM149K-Fc also resulted in higher killing of pleural mesothelioma cells by a tumor-specific CD8+ T cell clone in mesothelioma/macrophage spheroids.
sCSF-1RM149K-Fc efficiently traps both CSF-1 and IL-34 and inhibits CSF-1R signaling, monocyte survival and suppressive macrophage differentiation induced by pleural mesothelioma cells producing CSF-1 and IL-34, as well as restores cytotoxic T-cell responses. sCSF-1RM149K-Fc has therapeutic potential vs other therapies under development targeting single components of this complex cytokine pathway involved in cancer.
© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.

Despite the success of immune checkpoint inhibitors (ICIs) in multiple malignant tumors, a significant proportion of patients remain unresponsive to treatment. Radiotherapy (RT) elicits immunogenic antitumor responses but concurrently activates several immune evasion mechanisms. Our earlier research demonstrated the efficacy of YM101, an anti-TGF-β/PD-L1 bispecific antibody, in stroma-rich tumors. Nevertheless, YM101 has demonstrated reduced effectiveness in non-inflamed tumors characterized by poor immune cell infiltration. This study investigated the potential synergy between RT and YM101 in overcoming immunotherapy resistance and mitigating RT-induced pulmonary fibrosis.
The antitumor activity and survival outcomes of RT plus YM101 treatment in vivo were explored in several non-inflamed murine tumor models. Furthermore, the inhibition of pulmonary metastases was assessed in a pulmonary metastasis model. The impact of RT on dendritic cell (DC) maturation was quantified by flow cytometry, whereas cytokine and chemokine secretions were measured by ELISA. To comprehensively characterize changes in the tumor microenvironment, we utilized a combination of methods, including flow cytometry, IHC staining, multiplex inmunofluorecence and RNA sequencing. Additionally, we evaluated the impact of YM101 on RT-induced pulmonary fibrosis.
RT plus YM101 significantly inhibited tumor growth, prolonged survival and inhibited pulmonary metastases compared with monotherapies in non-inflamed tumors with poor immune infiltration. RT promoted DC maturation in a dose-dependent manner and increased the secretions of multiple proinflammatory cytokines. Mechanistically, RT plus YM101 simultaneously increased the infiltration and activation of intratumoral DCs and tumor-infiltrating lymphocytes and reshaped the tumor microenvironment landscape. Notably, YM101 attenuated both RT-induced peritumoral fibrosis and pulmonary fibrosis.
Our findings suggest that RT combined with YM101 enhances antitumor immunity and overcomes resistance in non-inflamed tumors in preclinical models, while simultaneously showing potential in mitigating RT-induced fibrosis. This combination therapy demonstrates promise in overcoming ICI resistance, while potentially sparing normal pulmonary tissue, thereby providing a strong rationale for further clinical investigations.
© 2025. The Author(s).

The development and maturation of B lymphocytes involve intricate orchestrated processes, where dedicated gene regulations (GR) take place within specific microenvironments shaped by both extracellular matrix and neighboring cells. Despite extensive investigations aimed at deepening our comprehension of these mechanisms, there remains a dearth of high-dimensional and integrated analysis concerning B cell heterogeneity, gene regulation, and external factors implicated in B cell development. In this study, we scrutinized single-cell transcriptomic data and B cell receptor (BCR) sequencing data obtained from B cells and their surrounding counterparts in the bone marrow, tonsil, and peripheral blood. A full picture of the GR dynamics, the heterogeneity of conventional B cells and cell-cell interactions (CCIs) along B cell development axis was depicted. We found immature B cells represent the most quiescent stage characterized by the least number of expressed genes and low RNA velocity. The homeostatic proliferation and activation of naive B cells is niche-confined and individualized, respectively. Two development models for memory B cell subpopulations seem not mutually exclusive and warrant in-depth investigation. Moreover, CCI analysis reveals a pivotal role of myeloid cells and two dominant and stage-dependent CCI categories, TNF and adhesion signaling, in B cell development. Besides, we unexpectedly identified two age-associated B cell subpopulations that respectively express S100A8/S100A9 and C1q and experimentally confirmed the secretion of S100A8/A9 from human B cells in vitro, suggesting a senescence-associated secretion phenotype. Our integrated analysis provides valuable insights into GR dynamics, the evolution of B cells, and potential intercellular communication networks involved in B cell development and revealed novel phenotypes of age-associated B cell aberrance. This study serves as a valuable resource for in-depth exploration of the intricacies of B cell biology.

Allergen-specific immunotherapy (AIT) induces immune tolerance, showing the highest success rate (>95%) for insect venom while a much lower chance for pollen allergy. However, the molecular switches leading to successful durable tolerance restoration remain elusive. The primary outcome of this observational study is the comprehensive immunological cellular characterization during the AIT initiation phase, whereas the secondary outcomes are the serological and Th2-cell-type-specific transcriptomic analyses. Here we apply a multilayer-omics approach to reveal dynamic peripheral immune landscapes during the AIT-initiation phase in venom allergy patients (VAP) versus pollen-allergic and healthy controls. Already at baseline, VAP exhibit altered abundances of several cell types, including classical monocytes (cMono), CD4+ hybrid type 1-type 17 cells (Th1-Th17 or Th1/17) and CD8+ counterparts (Tc1-Tc17 or Tc1/17). At 8-24 h following AIT launch in VAP, we identify a uniform AIT-elicited pulse of late-transitional/IL-10-producing B cells, IL-6 signaling within Th2 cells and non-inflammatory serum-IL-6 levels. Sequential induction of activation and survival protein markers also immediately occur. A disequilibrium between serum IL-6 and cMono in VAP baseline is restored at day seven following AIT launch. Our longitudinal analysis discovers molecular switches during initiation-phase insect-venom AIT that secure long-term outcomes. Trial number: NCT02931955.
© 2024. The Author(s).

Abstract Background Most current research has focused on the entire periodontal tissue, which restricts a comprehensive understanding of the heterogeneity between gingiva and bone tissues, and hinders the development of targeted host therapies for peri-implantitis. To uncover the pathogenic mechanisms of peri-implantitis, our study employed a tissue-specific approach to investigate the interactions between stromal and immune cells in gingiva and bone tissues separately, using single-cell sequencing techniques. This strategy aims to develop the insights of the pathogenesis of peri-implantitis, providing a scientific basis for the treatment of peri-implantitis. Methods Single-cell RNA sequencing transcriptomics profiling was conducted on samples from peri-implantitis-affected and healthy beagle dogs. Flow cytometry was utilized to further verify the identified subclusters and their involvement in peri-implantitis. Results In peri-implantitis, inflammation-associated cells increased, exhibiting distinct subclusters in gingival and bone tissues. In gingival tissues, IL6+ endothelial cells, IL18BP+ endothelial cells, and CXCL8+ fibroblasts played significant roles. APOD+ fibroblasts were predominantly found in bone tissues, while SFN+ fibroblasts were present in both tissues. Additionally, a unique ligand-receptor pair, C3 (APOD+ fibroblast) – C3AR1 (Monocyte/ Macrophage), was identified in bone tissue. Conclusions Stromal cells exert distinct regulatory influences on immune cells in gingival and bone tissues during peri-implantitis, offering new perspectives for studying the pathogenic mechanisms of the disease.