Biology subjects

Mulder, K.

Publications and source records attributed to Mulder, K..

7 recordsLinked to original sources

bioRxiv2026

Imaging guided single-cell multiomics unveils shared autoreactive CD4+ T-cell responses in blood, locoregional lymph node and affected tissues of patients with systemic autoimmunity

Systemic autoimmune connective tissue diseases (CTDs) are characterized by anti-nuclear antibodies, shared HLA-associated genetic risk, and frequent disease overlap, suggesting a central role for CD4+ T cells in pathogenesis. However, defining disease-driving CD4+ T-cell responses remains challenging due to their localization within lymphoid and affected tissues and the lack of approaches linking these responses to circulating counterparts. We combined [18F]-labeled thymidine PET/CT-guided tissue sampling, ex vivo antigen stimulation, and single-cell multiomics to characterize CD4+ T-cell responses in blood, PET-avid locoregional lymph nodes (LNs), and disease-affected tissues from patients with the immunologically distinct CTDs systemic sclerosis and Sjogren's disease. PET-avid LNs from both diseases exhibited enhanced adaptive immune activity and contained an expanded population of interferon-stimulated gene (ISG)-expressing TRAIL+ CD4+ T cells. In Sjogren's disease, active LNs and affected tissues harbored diverse effector CD4+ T-cell populations, including follicular and peripheral helper T cells and Th2/Th17 cells. In contrast, systemic sclerosis tissues lacked effector CD4+ T cells, while active LNs were enriched for naive, regulatory, and TRAIL+ ISG CD4+ T cells. Antigen stimulation of peripheral blood mononuclear cells enriched for expanded effector CD4+ T-cell populations that shared activation profiles and clonal relationships with cells in LNs and affected tissues, many representing autoreactive antigen-specific T cells. TRAIL+ CD4+ T cells suppressed effector T-cell differentiation, autoreactive plasma cell generation, and autoantibody production in vitro, identifying a previously unrecognized immunoregulatory population. Together, this workflow enables comprehensive characterization of pathogenic and regulatory CD4+ T-cell responses across CTDs.

immunology↗

bioRxiv2026

Monocytes promote intraepithelial infiltration of effector memory CD8+ T cells in regressing tumors

Despite the clinical success of cancer immunotherapies, the cellular interactions driving tumor regression remain incompletely understood. Here, we investigated the dynamic remodeling of the tumor immune microenvironment during regression of transplanted PyMT mammary tumors following STING agonist treatment. Using scRNA-seq of sorted CD8+ T cells and myeloid cells, combined with imaging approaches, we identified major changes in both lymphoid and myeloid compartments during tumor regression. Regressing tumors showed a transient accumulation of Ly6Chi monocyte populations associated with a decline in macrophage subsets, while effector and memory CD8+ T-cell populations increased at the expense of exhausted T cells. Interaction analyses predicted enhanced chemotactic and adhesion interactions between CXCL9+ Ly6Chi monocytes and effector CD8+ T cells. Consistently, dynamic imaging revealed increased CD8+ T-cell motility and infiltration into tumor cores following treatment. In particular, CXCR6+ effector CD8+ T cells transiently accumulated within tumor islets during regression before relocalizing to stromal regions. Together, these findings reveal a coordinated spatiotemporal remodeling of myeloid and CD8+ T-cell populations during immunotherapy-induced tumor regression and highlight cooperative interactions that may promote durable anti-tumor immunity.

immunology↗

bioRxiv2026

Distinct functions of PBRM1 and BAP1 reconcile the course of kidney cancer evolution and disease progression

Clear cell renal cell carcinoma (ccRCC) progresses along two predominant evolutionary trajectories, defined by PBRM1 ([~]40%) or BAP1 ([~]15%) mutations on a VHL-inactivated background. They have distinct patterns of evolutionary tempo and mode, and vastly different clinical outcomes, yet the underlying genotype-specific molecular phenotypic programmes are unknown. We established a patient-derived preclinical model biobank that captures the genetic diversity of ccRCC. Through integrative analyses of preclinical models and tumour bulk and single cell profiling, we identified transcriptional and epigenetic changes specific to PBRM1- and BAP1-driven ccRCC. Modelling PBRM1 loss in vitro demonstrates that it reinforces renal lineage identity and maintains progenitor-like cell state. In contrast, BAP1 loss drives inflammatory signalling and chromosomal instability. These insights reconcile the distinct evolutionary modes (branched versus punctuated), tempo (slow versus fast) and clinical outcomes associated with PBRM1 and BAP1 mutations, respectively, establishing a framework for patient stratification and genotype-directed therapeutic development.

cancer biology↗

bioRxiv2026

Single-cell trajectories in metastatic urothelial carcinoma reveal tumor-immune reprogramming and macrophage-driven resistance to PD-(L)1 blockade

Immune checkpoint inhibitors (ICI) improved outcomes in metastatic urothelial carcinoma (mUC), but primary and acquired resistance remain poorly understood. We performed single-nuclei RNA sequencing on sequential metastatic biopsies from ICI-treated mUC patients. Tumor cells showed transcriptomic heterogeneity within individual lesions, basal cells being associated with increased immune infiltration and response. Myeloid and lymphoid compartments exhibited features of immune dysfunction in non-responders. Longitudinal analyses revealed convergent adaptive resistance mechanisms, dominated by polarization toward pro-tumoral macrophage states, but also including downregulation of the antigen presentation machinery in tumor cells, increased checkpoint expression with loss of cytotoxicity in T cells. Individual trajectories point to distinct evolutionary routes under ICI pressure. Across pivotal ICI trials, bulk expression of the M2-like macrophage marker HES1 predicted ICI resistance. Our study provides the first single-cell longitudinal atlas of ICI-treated mUC, revealing macrophage reprogramming as a dominant driver of resistance, establishing a framework for individualized immunotherapy strategies.

cancer biology↗

bioRxiv2025

Methylome profiling of SetDB1 deficient ESCs reveals diverse epigenetic cross-talk during pluripotency

SetDB1 is best known as a chromatin modifier catalyzing H3K9me3. However, recent studies show that SetDB1 can promote H3K27me3-deposition and CTCF-binding, and potentially recruit de novo DNA methyltransferases. Given the tight connection with these processes, we hypothesized that DNA methylation (DNAme) may integrate these combined features of SetDB1. Thereto, we conducted time-course whole-genome bisulfite sequencing following Setdb1 knockout (KO) in mouse embryonic stem cells (ESCs). In serum-cultured ESCs, nearly half of SetDB1 binding sites are DNA methylated, coinciding with H3K9me3, mainly silencing retrotransposons and imprinting control regions. Both H3K9me3 and DNAme are lost upon Setdb1 KO, but while TET2 rapidly removes DNAme at many of these sites, some retrotransposons are shielded from TET2 and lose DNAme slowly via passive dilution. SetDB1-mediated regulation via H3K27me3, CTCF, SMAD3, and histone acetylation are uncoupled from the DNAme-H3K9me3 axis. Hypomethylated naive ESCs show massive reactivation of retrotransposons upon Setdb1 KO, providing functional evidence that DNAme adds a protective layer against such activity. Altogether, our findings reveal how DNAme coordinates the multifaceted regulatory roles of SetDB1. HighlightsO_LIIn serum ESCs, SetDB1-dependent deposition of H3K9me3 and DNAme are tightly coupled, primarily silencing repeats and imprinted control regions; C_LIO_LILoss of SetDB1 causes demethylation of a large range of repeat types, the pace of which is dependent on TET pre-loading; C_LIO_LIThe regulatory modes of SetDB1 mediated by H3K27me3, CTCF, TGF-{beta} signalling and histone acetylation are uncoupled from the SetDB1 DNAme-H3K9me3 axis and/or from each other; C_LIO_LILoss of SetDB1-dependent DNAme in hypomethylated 2i ESCs reveals that DNAme serves as a buffering layer to repress SetDB1-mediated H3K9me3 targets. C_LI

molecular biology↗

bioRxiv2023

Sopa: a technology-invariant pipeline for analyses of image-based spatial-omics

Spatial-omics data allow in-depth analysis of tissue architectures, opening new opportunities for biological discovery. In particular, imaging techniques offer single-cell resolutions, providing essential insights into cellular organizations and dynamics. Yet, the complexity of such data presents analytical challenges and demands substantial computing resources. Moreover, the proliferation of diverse spatial-omics technologies, such as Xenium, MERSCOPE, CosMX in spatial-transcriptomics, and MACSima and PhenoCycler in multiplex imaging, hinders the generality of existing tools. We introduce Sopa (https://github.com/gustaveroussy/sopa), a technology-invariant, memory-efficient pipeline with a unified visualizer for all image-based spatial omics. Built upon the universal SpatialData framework, Sopa optimizes tasks like segmentation, transcript/channel aggregation, annotation, and geometric/spatial analysis. Its output includes user-friendly web reports and visualizer files, as well as comprehensive data files for in-depth analysis. Overall, Sopa represents a significant step toward unifying spatial data analysis, enabling a more comprehensive understanding of cellular interactions and tissue organization in biological systems.

bioinformatics↗

bioRxiv2023

Integrative omics analysis reveals gene regulatory mechanisms distinguishing organoid-derived hepatocytes from primary human hepatocytes

Background and AimsHepatic organoid cultures are considered a powerful model system to study liver development and diseases in vitro. However, hepatocyte-like cells differentiated from such organoids remain immature compared to primary human hepatocytes. Therefore, a comprehensive understanding of differences in gene regulatory mechanisms between primary human hepatocytes and hepatic organoids is essential to obtain functional hepatocyte-like cells in vitro for fundamental and therapeutic applications. MethodsWe obtained primary human hepatocytes at high purity from all zones of the liver lobule using an optimized two-step perfusion protocol. We captured the single-cell transcriptome and chromatin accessibility landscape using scRNA-seq and ATAC-seq, respectively. We identified key transcription factors and compared the gene regulatory mechanisms in primary human hepatocytes and (un)differentiated intrahepatic cholangiocyte organoids. Using siRNA-mediated perturbations, we showed the functional relevance of an organoid-enriched transcription factor during in vitro differentiation of hepatocyte-like cells. ResultsOur integrative omics analysis revealed that Activator Protein 1 (AP-1) family members cooperate with hepatocyte-specific transcription factors, including HNF4A, in maintaining cellular functionality of mature human hepatocytes. Comparative analysis identified distinct transcription factor sets specifically active in human hepatocytes and organoids. Amongst these ELF3 is unique to intrahepatic cholangiocyte organoids and its expression level negatively correlate with expression of hepatic marker genes. Functional analysis of ELF3 furthermore revealed that ELF3 depletion optimizes the formation of hepatocyte-like cells from intrahepatic cholangiocyte organoids. ConclusionsCollectively, our integrative analysis provides insights into the transcriptional regulatory networks of human hepatocytes and hepatic organoids, thereby informing future strategies for better establishment of urgently-needed hepatic model systems in vitro.

molecular biology↗