Biology subjects

Kopf, A.

Publications and source records attributed to Kopf, A..

3 recordsLinked to original sources

bioRxiv2026

Alternatively polarized neutrophils metabolically restrain macrophage-driven inflammation

Macrophage-driven inflammation underlies many inflammatory diseases, yet the mechanisms that restrain macrophage activation within inflamed tissues remain poorly understood. Using mouse models of foreign body granuloma formation and macrophage activation syndrome, we show that neutrophils accumulate at sites of inflammation and metabolically restrain macrophage-driven pathology. Neutrophil depletion or genetic impairment exacerbated tissue pathology, whereas induced neutrophilia attenuated inflammatory damage. Tissue-infiltrating neutrophils acquired an alternatively polarized state characterized by high arginase 1 activity that was regulated by an IL4Ra-STAT3-NOX2 signaling axis. Functionally, polarized neutrophils depleted extracellular arginine in an arginase 1-dependent manner, thereby limiting macrophage effector programs. Human neutrophils exhibited conserved regulation of arginase activity, and alternatively polarized neutrophils were detected in patients with sarcoidosis and macrophage activation syndrome. Together, these findings identify an arginine-dependent metabolic mechanism through which alternatively polarized neutrophils restrain macrophage-driven inflammation and reveal a previously unrecognized immune-regulatory role for these cells in chronic inflammatory disease.

immunology↗

bioRxiv2025

Uncovering the transcriptional hallmarks of endothelial cell aging via integrated single-cell analysis

Endothelial cells (ECs) are critical regulators of vascular function and exhibit specialized, organ-specific roles across tissues. During aging, these cells become dysfunctional, resulting in increased susceptibility to cardiovascular disease and its associated mortality. While single-cell transcriptomics studies have revealed extensive endothelial heterogeneity across tissues and conditions, a comprehensive atlas of human EC transcriptomes over the course of the adult human lifespan is still lacking. Here, we present the Human Aging Endothelial Cell Atlas (HAECA), a harmonized single-cell transcriptomic compendium of over 375,000 ECs from 12 human tissues throughout adulthood. Using HAECA, we identified age-associated transcriptional shifts, including a decline in angiogenic gene expression in venous ECs and widespread alterations in extracellular matrix (ECM)- and mechanotransduction-associated pathways. We validated these findings in aging human skin and further uncovered a p21-linked transcriptional program in ECs, confirmed in both in vitro and in vivo models and linked to cellular senescence. Together, our study provides a high-resolution transcriptome reference across spatial as well as temporal axes of the human endothelium.

cell biology↗

bioRxiv2019

Microtubules coordinate protrusion-retraction dynamics in migrating dendritic cells

Cells navigating through tissues face a fundamental challenge: while multiple cellular protrusions explore different paths through the complex geometry of an interstitial matrix the cell needs to avoid becoming too long or ramified, which might ultimately lead to a loss of physical coherence. How a cell surveys its own shape to inform the actomyosin system to retract entangled or stretched protrusions is not understood. Here, we demonstrate that spatially distinct microtubule (MT) dynamics regulate amoeboid cell migration by locally specifying the retraction of explorative protrusions. In migrating dendritic cells (DCs), the microtubule organizing center (MTOC) guides the path through a three dimensional (3D) interstitium and local MT depolymerization in protrusions remote from the MTOC triggers myosin II dependent contractility via the RhoA exchange factor Lfc. Depletion of Lfc leads to aberrant myosin localization, thereby causing two effects that rate-limit locomotion: i) impaired cell edge coordination during path-finding and ii) defective adhesion-resolution. Such compromised cell shape control is particularly hindering when cells navigate through geometrically complex microenvironments, where it leads to entanglement and ultimately fragmentation of the cell body. Our data demonstrate that MTs control cell shape and coherence by locally controlling protrusion-retraction dynamics of the actomyosin system.

cell biology↗