Szot, G. L. | Search bioRxiv

bioRxiv2026

The Spatial Landscape of Extracellular Matrix Gene Expression in Healthy and Type 2 Diabetic Human Pancreas

The unique peri-islet and double-layered vascular basement membrane (BM) of the human pancreatic islet are critical regulators of beta cell survival and function. While animal models imply that endothelial cells (ECs) are the exclusive source of islet BM, the precise cellular origins and spatial organization of the human islet matrisome remain poorly defined due to overlap in genes that mark non-epithelial cell populations and loss of spatial context during single-cell dissociation. In this study, we combine computational integration of whole-pancreas single-cell transcriptomes using CONCORD with high-resolution MERFISH spatial genomics to map the extracellular matrix (ECM) landscape across 251,477 spatially resolved cells from seven non-diabetic and five type 2 diabetic human donors. Contrary to an endothelial-centric paradigm, our data support a cooperative division of labor in the provision of BM, where pericytes represent the dominant transcriptional source of structural BM collagens (COL4A1, COL4A2) and ECs selectively express complementary matrix factors (HSPG2, LAMA5). Spatial neighborhood analysis further resolves a specialized population of islet-associated fibroblasts enriched at the islet boundary that are characterized by expression of peri-islet laminin genes. In type 2 diabetes, this homeostatic perivascular niche changes composition, marked by a significant increase in the islet fibroblast-to-pericyte ratio. Concurrently, islet pericytes undergo pro-fibrotic reprogramming characterized by the loss of canonical identity markers (PDGFRB), altered expression of ECM genes including COL1A2 and COL18A1, and upregulation of contractile machinery (MYL9). In the non-diabetic pancreas, pericytes constitute the principal vascular BM-expressing population within islets, whereas type 2 diabetes is associated with coordinated, compartment-specific remodeling of vascular-supportive stromal populations. Research in ContextO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIExtracellular matrix (ECM), and in particular basement membrane (BM), are essential structural and signaling components of the pancreatic islet microenvironment that contribute to beta cell function and survival. C_LIO_LIIslet capillaries are closely associated with endocrine cells and are surrounded by specialized BMs; however, the cellular sources of these BM components in the adult human pancreas remain incompletely defined. C_LIO_LIType 2 diabetes is associated with islet fibrosis and vascular dysfunction, but cell type-specific alterations in ECM-producing populations have not been comprehensively characterized in situ. C_LI What is the key question?O_LIWhich cell populations produce the components of ECM, including BM, within the adult human islet, and how are these populations altered in type 2 diabetes? C_LI What are the new findings?O_LISpatial transcriptomics identifies pericytes as the predominant vascular-associated source of ECM, including BM, gene expression in human islets, whereas endothelial cells exhibit complementary but more limited matrix-producing programs. C_LIO_LISpatial transcriptomics identifies an islet-associated fibroblast population enriched for fibrillar collagen and BM-associated genes that localizes preferentially to the islet surface niche. C_LIO_LIType 2 diabetes is associated with remodeling of perivascular ECM programs, including reduced expression of vascular basement membrane genes, a shift from a pericyte to smooth muscle-like identity, and increased expression of matrix-remodeling and fibrosis-associated genes. C_LI How might this impact clinical practice in the foreseeable future?O_LIDefining the cellular sources and disease-associated remodeling of the human islet ECM may inform the development of therapies aimed at preserving or restoring the islet microenvironment in type 2 diabetes. C_LIO_LIIncluding key subtypes of islet-associated ECM-producing cells may be important in improving current protocols to generate replacement islets from human pluripotent stem cells for cell replacement therapy for diabetes. C_LI

cell biology↗

bioRxiv2021

Single-cell sequencing unveils distinct immune microenvironment with CCR6-CCL20 crosstalk in human chronic pancreatitis

ObjectiveChronic pancreatitis (CP) is a potentially fatal disease of the exocrine pancreas, with no specific or effective approved therapies. Due to difficulty in accessing pancreas tissues, little is known about local immune responses or pathogenesis in human CP. We sought to characterize pancreas immune responses using tissues derived from patients with different etiologies of CP and non-CP organ donors in order to identify key signaling molecules associated with human CP. DesignWe performed single-cell level cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq) and T cell receptor sequencing of pancreatic immune cells isolated from organ donors, hereditary, and idiopathic CP patients who underwent total pancreatectomy. We validated gene expression data by performing flow cytometry and functional assay in the second CP patient cohort. ResultsDeep single-cell sequencing revealed distinct immune characteristics and significantly enriched CCR6+ CD4+ T cells in hereditary compared with idiopathic CP. In hereditary CP, a reduction in T cell clonality was observed due to the increased CD4+ T (Th) cells that replaced tissue-resident CD8+ T cells. Shared TCR clonotype analysis among T cell lineages also unveiled unique interactions between CCR6+ Th and Th1 subsets, and TCR clustering analysis showed unique common antigen binding motifs in hereditary CP. In addition, we observed a significant upregulation of the CCR6 ligand (CCL20) among monocytes in hereditary CP as compared with those in idiopathic CP. The functional significance of CCR6 expression in CD4+ T cells was confirmed by flow cytometry and chemotaxis assay. ConclusionSingle-cell sequencing with pancreatic immune cells in human CP highlights pancreas-specific immune crosstalk through the CCR6-CCL20 axis that might be leveraged as a potential future target in human hereditary CP. Significance of this studyO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIChronic pancreatitis (CP) is considered an irreversible fibroinflammatory pancreatic disease and remains a major source of morbidity among gastrointestinal diseases with no active approved therapy. C_LIO_LIInflammation is a known hallmark and contributor to CP pathogenesis. However, little is known about local immune responses in human CP especially with different etiologies. C_LI What are the new findings?O_LISingle-cell RNA sequencing of pancreatic immune cells from CP patients and organ donors revealed distinct immune transcriptomic features in CP versus non-diseased controls and hereditary versus idiopathic CP. C_LIO_LISingle-cell T cell receptor sequencing unveiled pancreas-specific clonal expansion in CD8+ T cells and CD4+ T cells-driven unique TCR repertoire changes in hereditary CP. C_LIO_LIWe identified that the CCR6-CCL20 axis was significantly upregulated in hereditary CP compared with controls or idiopathic CP suggesting a potential future target for human hereditary CP. C_LI How might it impact on clinical practice in the foreseeable future?O_LIThe results of this study will improve our understanding of CP heterogeneity and identify distinct immune responses in different types of human CP that could provide novel conceptual directions for therapeutic strategies in treating hereditary and idiopathic CP. C_LIO_LIThe CCR6-CCL20 axis found in hereditary CP could be a potential novel targetable signaling pathways in the treatment of hereditary CP. C_LI

immunology↗