Selective activation and proliferation of a quiescent stem cell population in the neuroepithelial body microenvironment

Abstract

BackgroundThe microenvironment (ME) of neuroepithelial bodies (NEBs) harbors densely innervated groups of pulmonary neuroendocrine cells that are covered by Clara-like cells (CLCs) and is believed to be important during development and for adult airway epithelial repair after severe injury. Yet, little is known about its potential stem cell characteristics in healthy postnatal lungs.MethodsTransient mild lung inflammation was induced in mice via a single low-dose intratracheal instillation of lipopolysaccharide (LPS). Bronchoalveolar lavage fluid (BALF), collected 16 h after LPS instillation, was used to challenge the NEB ME in ex vivo lung slices of control mice. Proliferating cells in the NEB ME were identified and quantified following simultaneous LPS instillation and BrdU injection.ResultsThe applied LPS protocol induced very mild and transient lung injury. Challenge of lung slices with BALF of LPS-treated mice resulted in selective Ca2+-mediated activation of CLCs in the NEB ME of control mice. Forty-eight hours after LPS challenge, a remarkably selective and significant increase in the number of divided (BrdU-labeled) cells surrounding NEBs was observed in lung sections of LPS-challenged mice. Proliferating cells were identified as CLCs.ConclusionsA highly reproducible and minimally invasive lung inflammation model was validated for inducing selective activation of a quiescent stem cell population in the NEB ME. The model creates new opportunities for unraveling the cellular mechanisms/pathways regulating silencing, activation, proliferation and differentiation of this unique postnatal airway epithelial stem cell population.

Pulmonary neuroendocrine cells: physiology, tissue homeostasis and disease

“…PNEC depolarization evokes Ca 2+ -mediated ATP release and activates these club-like cells via P2Y purinergic receptors, suggesting a functional coupling between PNECs and vClub cells ( Schnorbusch et al, 2013 ). By contrast, a mild injury model induced with lipopolysaccharide (LPS; Box 1 ) selectively evokes oscillations in Ca 2+ levels and proliferation of club-like cells, but with no PNEC activation ( Verckist et al, 2018 ), suggesting that PNECs specifically respond to severe injury – such as that from naphthalene – and may supply niche factors for surrounding cells.…”

Calcium-sensing receptor antagonism as a novel therapeutic for pulmonary fibrosis

“…They also represent a unique stem cell niche involved in airway epithelium repair. [29] Particularly relevant to our findings is the strong surface membrane expression of fully functional CaSR reported in mouse NEBs. [28] Among several other bioactive substances, human NEBs synthesize, store and secrete GRP in health and disease,[30] which is implicated in (myo)fibroblast proliferation, collagen synthesis and alveolar wall thickening in pulmonary fibrosis.…”

Inflammatory auxo-action in the stem cell division theory of cancer

“…Reactive oxygen species (ROS) generated during tissue damage and infection are important cues linking inflammation to intestinal stem cells (ISCs) proliferation through activating Jun N-terminal kinases (JNKs) and inhibiting nuclear factor erythroid2-related factor 2 (Nrf2) signal ( Hochmuth et al, 2011 ; Biteau, Hochmuth & Jasper, 2008 ). Lipopolysaccharide (LPS) -induced transient mild inflammation stimulates the selective activation and proliferation of stationary stem cell populations, such as Clara-like cells (CLCs) ( Verckist et al, 2018 ). Moreover, IFN- γ treatment increased the expression of bone marrow stromal cell antigen 2 (BST2), a cell surface protein essential for INF γ -dependent hematopoietic stem cell (HSC) activation, thereby disrupting HSC quiescence and promoting excessive terminal differentiation ( Florez et al, 2020 ).…”