Project description:There is an increasing need for pharmacological treatments that target defective epithelial repair in chronic diseases, such as chronic obstructive pulmonary disease. The mesenchymal niche plays a major regulatory role in guiding epithelial progenitor cell activation during repair. We persuaded that the secreted factors involved in this interaction hold potential as drug targets. In this study, we utilized a proteomics-guided drug discovery strategy, leveraging the secretome of lung fibroblasts, to uncover drug targets affecting epithelial progenitor behavior. Using lung organoids, we identified several ligands with regenerative potential, of which the matrix protein osteoglycin (OGN) surprisingly had the most profound effect. RNA sequencing revealed that OGN promoted alveolar epithelial type II cell differentiation, whilst increasing reactive oxygen species detoxification, reducing senescence, and enhancing growth factor-mediated fibroblast- epithelial crosstalk. In accordance with this OGN protein expression was reduced in damaged lung tissue of COPD patients and in smoke-exposed mice. Additionally, we found an active fragment of OGN comprising the leucine-rich repeat regions 4-7 to have comparable regenerative potential in regulating lung organoid formation. The active fragment of OGN ameliorated elastase-induced lung injury in precision-cut lung slices (PCLS) and improved lung function in mice. These findings identify lung fibroblast-derived OGN as a matrix protein supporting alveolar epithelial growth and its active fragment as a promising therapeutic target for epithelial cell repair in individuals with accelerated tissue damage.
Project description:Integrins are extracellular matrix receptors comprised of an a and b subunit that connect and mediate signaling between cells and the surrounding matrix. In organogenesis of epithelial tissues, the b1 integrin subunit regulates essential epithelial cell functions, but the role of b1 integrin in epithelial repair is poorly understood. To define the role of b1 integrin during alveolar repair, we challenged b1 integrin deficient mice with intratracheal lipopolysaccharide, resulting in increased mortality with emphysematous lungs 21 days following injury. The alveolar barrier was repopulated with an overabundance of type 2 alveolar epithelial cells, with reduced numbers of elongated alveolar type 1 cells, suggesting b1 integrin is required for type 2 to type 1 epithelial transition. Consistent with this finding, b1 deficient type 2 epithelial cells proliferated at increased rates throughout repair, lacked actin-rich cellular protrusions necessary for lateral cellular extension, and exhibited transcriptomic dysregulation of adherens junction and actin polymerization pathways. Finally, we show that b1 integrin balances actin polymerization versus stabilization through GTPase activation. Taken together, these data support a novel role for b1 integrin in re-establishing the alveolar niche after injury through modulation of type 2 epithelial cell proliferation and cytoskeletal-dependent cell shape change.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, and lethal lung disease. The initiation of IPF involves microinjuries to and/or dysfunction of the alveolar epithelium, but factors that determine fibrosis progression or normal tissue repair are largely unknown. We previously demonstrated that autophagy inhibition-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments local myofibroblast differentiation in pulmonary fibrosis by paracrine signalling. Here, we report that liver kinase B1 (LKB1) inactivation in ATII cells induces autophagy inhibition and EMT as a consequence. In IPF lungs, this is caused by a downregulation of CAB39L, a key subunit within the LKB1 complex. 3D co-cultures of ATII cells and lung fibroblast MRC5 coupled with RNA sequencing (RNA-seq) confirmed that paracrine signalling between LKB1-depleted ATII cells and fibroblasts augmented myofibroblast differentiation. Together these data suggest that reduced autophagy caused by LKB1 inhibition can induce EMT in ATII cells and contribute to fibrosis via aberrant epithelial–fibroblast crosstalk.
Project description:Type 2 alveolar epithelial cells (AEC2s) are stem cells in the adult lung that contribute to lower airway repair. Agents that promote the selective expansion of these cells might stimulate regeneration of the compromised alveolar epithelium, an etiology defining event in several pulmonary diseases. From a high content imaging screen of the drug repurposing library ReFRAME, we identified that dipeptidyl peptidase 4 (DPP4) inhibitors, widely used type 2 diabetes medications, selectively expand AEC2s and are broadly efficacious in several mouse models of lung damage. Mechanism of action studies revealed that the protease DPP4, in addition to processing incretin hormones, degrades IGF-1 and IL-6, essential regulators of AEC2 expansion whose levels are increased in the luminal compartment of the lung in response to drug treatment. To selectively target DPP4 in the lung with sufficient drug exposure, we developed NZ-97, a locally delivered, lung persistent DPP4 inhibitor that broadly promotes efficacy in mouse lung damage models with minimal peripheral exposure and good tolerability. This work reveals DPP4 as a central regulator of AEC2 expansion and affords a promising therapeutic approach to broadly stimulate regenerative repair in pulmonary disease.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, and lethal lung disease. The initiation of IPF involves microinjuries to and/or dysfunction of the alveolar epithelium, but factors that determine fibrosis progression or normal tissue repair are largely unknown. We previously demonstrated that autophagy inhibition-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments local myofibroblast differentiation in pulmonary fibrosis by paracrine signalling. Here, we report that liver kinase B1 (LKB1) inactivation in ATII cells induces autophagy inhibition and EMT as a consequence. In IPF lungs, this is caused by a downregulation of CAB39L, a key subunit within the LKB1 complex. 3D co-cultures of ATII cells and lung fibroblast MRC5 coupled with RNA sequencing (RNA-seq) confirmed that paracrine signalling between LKB1-depleted ATII cells and fibroblasts augmented myofibroblast differentiation. Together these data suggest that reduced autophagy caused by LKB1 inhibition can induce EMT in ATII cells and contribute to fibrosis via aberrant epithelial–fibroblast crosstalk.
Project description:We established a novel alveolar epithelial culture method, called "On-Gel" culture. To characterize the "On-Gel" culture, we compared each transcriptome of the cultured cells in "On-Gel", fibroblast dependent-alveolar organoids (FD-AO) and fibroblast-free alveolar organoids (FF-AO) and their progenitor cells (CPMhigh Lung Progenitors).
Project description:Hypercapnia has deleterious effects on cell function, including inhibition of alveolar epithelial cells (AEC) and fibroblast proliferation without causing cell death. Classical studies and lineage-trace models demonstrated that fibroblast cells can affect the structurally and functionally distinct alveolar type 1 cells (AT1) and alveolar type 2 cells. This fibroblast cells reprogramming depends on certain signaling pathways that plays critical roles in tissue development and homeostasis throughout the organism lifespan.