Project description:Wnt ligands oligomerize Frizzled (Fzd) and Lrp5/6 receptors to control the specification and activity of stem cells in many species. How Wnt is selectively activated in different stem cell populations, often within the same organ, is not understood. In lung alveoli, wherein Wnt-dependent epithelial and stromal progenitors are intermingled, we show that distinct Wnt receptors are expressed by epithelial (Fzd5/6), endothelial (Fzd4), and stromal (Fzd1) cells. Moreover, Fzd5 was uniquely required for alveolar epithelial stem cell activity. However, by developing an expanded repertoire of Fzd-Lrp agonists (FLAgs), we could activate canonical Wnt signaling in alveolar epithelial stem cells via either Fzd5 or, unexpectedly, non-canonical Fzd6. Fzd5 and Fzd6 FLAgs stimulated supra-physiological alveolar epithelial stem cell activity in mice following lung injury, but only Fzd6 FLAg promoted an alveolar fate in airway-derived progenitors. Therefore, we identify a potential strategy for promoting regeneration without exacerbating fibrosis during lung injury.
Project description:Following lung injury, alveolar regeneration is characterized by the transformation of alveolar type 2 (AT2) cells, via a transitional KRT8+ state, into alveolar type 1 (AT1) cells. In lung disease, dysfunctional intermediate cells accumulate, AT1 cells are diminished and fibrosis occurs. Using single cell RNA sequencing datasets of human interstitial lung disease, we found that interleukin-11 (IL11) is specifically expressed in aberrant KRT8 expressing KRT5-/KRT17+ and basaloid cells. Stimulation of AT2 cells with IL11 or TGFβ1 caused EMT, induced KRT8+ and stalled AT1 differentiation, with TGFβ1 effects being IL11 dependent. In bleomycin injured mouse lung, IL11 was increased in AT2-derived KRT8+ cells and deletion of Il11ra1 in lineage labeled AT2 cells reduced KRT8+ expression, enhanced AT1 differentiation and promoted alveolar regeneration, which was replicated in therapeutic studies using anti-IL11. These data show that IL11 maintains AT2 cells in a dysfunctional transitional state, impairs AT1 differentiation and blocks alveolar regeneration across species.
Project description:Surfactant deficiency, diffuse alveolar damage and respiratory failure caused by loss of Abca3 in AT2 cells was followed by remarkable proliferation of alveolar cells and selective survival of ABCA3 sufficient cells resulting in regeneration of alveolar structure and function, providing the conceptual framework for the development of therapies to ameliorate lung diseases caused by mutations in ABCA3 and other genes critical for AT2 cell function or surfactant homeostasis.
Project description:Alveolar epithelial type 2 (AT2) cells are facultative progenitor cells that drive adult alveolar regeneration after acute lung injury. Using transcriptomic analyses from in vivo mouse injury models, we define the role of Tfcp2l1 in regulating AT2 cell behavior during lung regeneration.
Project description:Alveolar epithelial type 2 (AT2) cells are facultative progenitor cells that drive adult alveolar regeneration after acute lung injury. Using transcriptomic analyses from in vivo mouse injury models, we define the role of Tfcp2l1 in regulating AT2 cell behavior during lung regeneration.
Project description:Tissue regeneration is a multi-step process mediated by diverse cellular hierarchies and states that are also implicated in tissue dysfunction and pathogenesis. Here, we leveraged single-cell RNA sequencing in combination with in vivo lineage tracing and organoid models to finely map the trajectories of alveolar lineage cells during injury repair and lung regeneration. We identified a distinct AT2-lineage population, Damage-Associated Transient Progenitors (DATPs), that arises during alveolar regeneration. We found that interstitial macrophage-derived IL-1β primes a subset of AT2 cells expressing Il1r1 for conversion into DATPs via a HIF1α-mediated glycolysis pathway, which is required for mature AT1 cell differentiation. Importantly, chronic inflammation mediated by IL-1β prevents AT1 differentiation, leading to aberrant accumulation of DATPs and impaired alveolar regeneration. Together, this step-wise mapping to cell fate transitions shows how an inflammatory niche impairs alveolar regeneration by controlling stem cell fate and behavior.
Project description:Tissue regeneration is a multi-step process mediated by diverse cellular hierarchies and states that are also implicated in tissue dysfunction and pathogenesis. Here, we leveraged single-cell RNA sequencing in combination with in vivo lineage tracing and organoid models to finely map the trajectories of alveolar lineage cells during injury repair and lung regeneration. We identified a distinct AT2-lineage population, Damage-Associated Transient Progenitors (DATPs), that arises during alveolar regeneration. We found that interstitial macrophage-derived IL-1β primes a subset of AT2 cells expressing Il1r1 for conversion into DATPs via a HIF1α-mediated glycolysis pathway, which is required for mature AT1 cell differentiation. Importantly, chronic inflammation mediated by IL-1β prevents AT1 differentiation, leading to aberrant accumulation of DATPs and impaired alveolar regeneration. Together, this step-wise mapping to cell fate transitions shows how an inflammatory niche impairs alveolar regeneration by controlling stem cell fate and behavior.
Project description:Tissue regeneration is a multi-step process mediated by diverse cellular hierarchies and states that are also implicated in tissue dysfunction and pathogenesis. Here, we leveraged single-cell RNA sequencing in combination with in vivo lineage tracing and organoid models to finely map the trajectories of alveolar lineage cells during injury repair and lung regeneration. We identified a distinct AT2-lineage population, Damage-Associated Transient Progenitors (DATPs), that arises during alveolar regeneration. We found that interstitial macrophage-derived IL-1β primes a subset of AT2 cells expressing Il1r1 for conversion into DATPs via a HIF1α-mediated glycolysis pathway, which is required for mature AT1 cell differentiation. Importantly, chronic inflammation mediated by IL-1β prevents AT1 differentiation, leading to aberrant accumulation of DATPs and impaired alveolar regeneration. Together, this step-wise mapping to cell fate transitions shows how an inflammatory niche impairs alveolar regeneration by controlling stem cell fate and behavior.