Biology subjects

Engelhardt, J. F.

Publications and source records attributed to Engelhardt, J. F..

5 recordsLinked to original sources

bioRxiv2026

KRT7CreER Ferrets Enable Lineage Tracing of Ductal Epithelia and Pancreatic Remodeling

Keratin 7 (KRT7) is expressed in simple and ductal epithelia and is associated with epithelial plasticity during development, injury, and disease. However, the in vivo fate and regenerative behavior of KRT7 cells remain poorly defined because lineage-tracing models are lacking in species that closely recapitulate human disease. To address this gap, we generated KRT7CreER ferrets and crossed them with ROSAmTmG Cre-reporter ferrets, with or without the CFTRG551D/G551D mutation. Following tamoxifen induction, KRT7-derived EGFP cells were identified in glandular and ductal epithelia across multiple organs. Pulse-chase lineage tracing revealed that KRT7BSND cells turn over rapidly during salivary gland development. In the pancreas, KRT7 lineage-labeled cells are present at all levels of the ductal tree under homeostatic conditions. In cystic fibrosis (CF) ferrets, KRT7-derived centroacinar cells and intercalated ductal lineages persisted and underwent marked remodeling, characterized by expansion of the SOX9 centroacinar cell pod into intercalated ducts. Although acinar cells were not lineage-labeled in the healthy pancreas, EGFP/CELA3B cells emerged in the CF pancreas and in acinar-derived organoids, consistent with induction of KRT7 during acinar-to-ductal metaplasia. These findings establish KRT7CreER ferrets as a versatile model for studying ductal epithelial lineage dynamics, pancreatic remodeling, and epithelial plasticity in both homeostatic and pathological conditions.

pathology↗

bioRxiv2026

KRT7 Marks an Airway Glandular Ductal Stem Cell Population That Supports Multilineage Development and Regeneration

Airway submucosal glands (SMGs) play a central role in host defense through mucus secretion, airway hydration, and mucociliary clearance. However, the hierarchical organization of glandular progenitor populations remains poorly defined, largely because SMGs are sparse and restricted to the proximal trachea in murine models. Using the ferret, a model that closely recapitulates the gland-rich submucosal architecture of human cartilaginous airways, we identify KRT7+ glandular ductal epithelial cells as a progenitor population. In both adult ferret and healthy human airways, KRT7 expression is primarily restricted to the SMG duct epithelium, where it is co-expressed with KRT19 and CD166 but only partially overlaps with ALDH1A1. During early postnatal development, KRT7 expression becomes progressively restricted to glandular ductal epithelium and is ultimately excluded from mature acinar, myoepithelial cells, and KRT5+/KRT14+ basal lineages. Fate mapping in KRT7CreER;ROSAmTmG transgenic ferrets revealed that KRT7-lineage cells serve as multipotent progenitors during SMG morphogenesis, generating both serous and mucous epithelial cells. Following severe airway injury, KRT7-lineage cells survive within gland ducts and rapidly expand to repair the damaged surface epithelium by differentiating into ciliated and secretory cells but not KRT5+ basal cells. In organoid cultures, glandular KRT7-lineage cells acquired a KRT5+ basal-like phenotype and generated multilineage epithelia with functional CFTR-mediated transport. These findings identify the KRT7+ ductal niche as a critical progenitor reservoir for airway development, homeostasis, and regeneration, with implications for cystic fibrosis therapies.

cell biology↗

bioRxiv2026

Lef1 Promotes Foxi1-Dependent Ionocyte Specification by Airway Submucosal Gland Progenitors

Pulmonary ionocytes are rare cells in submucosal gland (SMG)-containing airways thought to have specialized ion transport properties that regulate airway surface fluid and mucus composition. The origins of pulmonary ionocytes remain unclear, but their association with airway SMGs suggests they may arise from specialized progenitors in this compartment. We show that mouse glandular myoepithelial cells (GMECs) have a unique capacity to specify ionocytes enriched in the Cftr channel. The Lef1 transcription factor was both necessary and sufficient to promote GMEC specification of ionocytes in mouse trachea, 3D organoids, and/or air-liquid interface (ALI) cultures. Overexpression of Lef1 (Lef1OE) in GMECs produced ionocyte-enriched epithelia with enhanced Cftr-mediated chloride, bicarbonate, and fluid transport properties. Moreover, Foxi1 knockout in Lef1OE GMECs prevented ionocyte formation while promoting specification of Cftr-expressing secretory cells. These findings provide a progenitor relationship for the anatomical association of ionocytes with SMGs and a transcriptional framework for coordinated specification of CFTR-expressing ionocytes and secretory cells.

cell biology↗

bioRxiv2026

Ncf1/Igfbp2 Signaling Regulates Airway Submucosal Gland Progenitor Fitness and Ionocyte Specification

Background: Airway submucosal gland progenitors (SMGPs) serve as reserve stem cells for epithelial regeneration, yet mechanisms governing their long-term maintenance remain poorly understood. Here, we identify Ncf1/Igfbp2 signaling as a regulator of mouse SMGP fitness and epithelial lineage specification. Methods: Mouse SMGPs with genetic disruption of Ncf1 or Igfbp2 were serially passaged to assess progenitor proliferation, organoid-forming capacity, epithelial marker expression, DNA damage, DNA repair responses, and telomere length. Differentiated epithelia were evaluated for Cftr-mediated anion transport and pulmonary ionocyte specification in vitro and in vivo. Results: Genetic disruption of Ncf1 or Igfbp2 preserved SMGP identity, enhanced proliferative and organoid-forming capacity, and reduced DNA damage accumulation through activation of DNA repair programs. Epithelia derived from Ncf1-/- and Igfbp2-/- SMGPs maintained higher Cftr-mediated anion transport at late passage and exhibited enhanced pulmonary ionocyte specification in vitro and in vivo. These effects occurred independently of telomere shortening, implicating altered stress responses and DNA damage handling rather than replicative limits. Conclusions: Together, our findings identify Ncf1/Igfbp2 signaling as a regulator of airway stem cell fitness and epithelial maturation, with implications for regenerative therapies in lung diseases such as cystic fibrosis.

cell biology↗

bioRxiv2025

Ferret model of bleomycin-induced lung injury shares features of human idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung disease with limited therapeutic options. The development of effective therapies has been hindered by the lack of models that recapitulate key features of human disease. Here we report a bleomycin-induced ferret PF model characterized by an irreversible decrease in pulmonary compliance and an increase of opacification, accompanied by "honeycomb cyst-like" structures and "proximalization" of distal lung epithelium. Cellular and molecular analysis by single-nucleus RNA sequencing revealed a significant shift in distal lung epithelium towards proximal epithelial phenotype. Importantly, a histopathological pattern of bronchiolization encompassing divergent atypical epithelial cells and KRT17+/TP63+/KRT5low "basaloid-like" cells was present in the distal fibrotic lung lesions. Trajectory analysis revealed AT2 cells transition through multiple cell-states in bleomycin injured ferret lungs, particularly AT2 to KRT8high/KRT7low/SOX4+ and eventually to KRT8high/KRT7high/SFN+/TP63+/KRT5low "basaloid-like" cells. Further, immunofluorescence analyses demonstrated KRT7 and KRT8 populations reside overlaying the ACTA2-positive myofibroblasts in fibrotic foci, implying their pro-fibrogenic activity similar to human IPF lungs. Collectively, our results provide evidence that bleomycin-induced lung injury in ferrets recapitulates pathophysiological, cellular, and molecular features of human IPF, suggesting that they may be a reliable model for understanding mechanisms of IPF pathogenesis and for testing therapeutic strategies for treatment of IPF. Take Home MessageBleomycin-induced acute lung injury in the ferret recapitulates pathophysiological, cellular, and molecular features of human IPF; thus the ferret may be a reliable species for studying mechanisms of IPF pathogenesis and testing therapeutic strategies.

pathology↗