Project description:Claudin proteins are major constituents of epithelial and endothelial tight junctions (TJ), where they serve as regulators of paracellular permeability to ions and solutes. Claudin-18, a member of the large claudin family, is highly expressed in lung epithelium. To elucidate the role of claudin-18 in alveolar epithelial barrier function and fluid homeostasis, we generated claudin-18 knockout (C18 KO) mice. Increased alveolar fluid clearance (AFC) observed in C18 KO mice may have accounted for absence of lung edema despite increased alveolar solute permeability compared to wild type (WT) controls. Higher AFC in C18 KO mice was associated with higher Na-K-ATPase activity and increased expression of the Na-K-ATPase β1 subunit compared to WT controls. Consistent with in vivo findings, alveolar epithelial cell (AEC) monolayers derived from C18 KO mice exhibited lower transepithelial electrical resistance (RT) accompanied by increased solute and ion permeability without changes in ion selectivity. Expression of claudin-3 and claudin-4 was markedly increased in whole lung and in freshly isolated AEC from C18 KO mice, while claudin-5 was unchanged. In contrast, occludin, another major component of the TJ complex, was significantly decreased in C18 KO lung. Further analysis revealed rearrangements in the F-actin cytoskeleton in C18 KO MAECM. These findings demonstrate a crucial non-redundant role for claudin-18 in regulation of alveolar epithelial tight junction composition and permeability to ions and solutes. Importantly, increased AFC in C18 KO mice identifies additional roles for claudin-18 in alveolar fluid homeostasis beyond its direct contributions to barrier properties of the alveolar epithelium. Animals with a ubiquitous knockout (C18 KO) were obtained by crossing mice harboring a conditional (floxed) allele of claudin-18 (Cldn18F/F) with CMV-cre deleter mice to delete exons 2 and 3 by Cre/loxP recombination.
Project description:Claudin proteins are major constituents of epithelial and endothelial tight junctions (TJ), where they serve as regulators of paracellular permeability to ions and solutes. Claudin-18, a member of the large claudin family, is highly expressed in lung epithelium. To elucidate the role of claudin-18 in alveolar epithelial barrier function and fluid homeostasis, we generated claudin-18 knockout (C18 KO) mice. Increased alveolar fluid clearance (AFC) observed in C18 KO mice may have accounted for absence of lung edema despite increased alveolar solute permeability compared to wild type (WT) controls. Higher AFC in C18 KO mice was associated with higher Na-K-ATPase activity and increased expression of the Na-K-ATPase β1 subunit compared to WT controls. Consistent with in vivo findings, alveolar epithelial cell (AEC) monolayers derived from C18 KO mice exhibited lower transepithelial electrical resistance (RT) accompanied by increased solute and ion permeability without changes in ion selectivity. Expression of claudin-3 and claudin-4 was markedly increased in whole lung and in freshly isolated AEC from C18 KO mice, while claudin-5 was unchanged. In contrast, occludin, another major component of the TJ complex, was significantly decreased in C18 KO lung. Further analysis revealed rearrangements in the F-actin cytoskeleton in C18 KO MAECM. These findings demonstrate a crucial non-redundant role for claudin-18 in regulation of alveolar epithelial tight junction composition and permeability to ions and solutes. Importantly, increased AFC in C18 KO mice identifies additional roles for claudin-18 in alveolar fluid homeostasis beyond its direct contributions to barrier properties of the alveolar epithelium.
Project description:Many lung diseases remain understudied due to a lack of experimental models. Lung organoids, which consist of self-organizing epithelial cells, provide versatile in vitro models for normal and abnormal biology, drug screening, gene editing, and personalized therapeutics. However, human organoids are generally derived from lung tissue, which is not commonly obtained and represents only a small fraction of lung pathologies. Induced pluripotent stem cells have provided an important alternative but require complex manipulation. Recently, one study reported airway organoids from bronchoalveolar lavage (BAL) fluid, though sample sizes and characterization were limited. Here, we demonstrate robust establishment of airway organoids from a variety of human BAL samples and show that these organoids consist predominantly of basal cells plus differentiated airway cell types including secretory, ciliated, KRT13+ “hillock,” and ionocyte cells. Furthermore, we report the development of BAL-derived alveolar organoids comprised of alveolar type 2 (AT2) cells. These techniques significantly expand the scope of lung diseases that can be studied using safely accessible primary human cells.
Project description:A comparative analysis of the protein content in bronco alveolar lavage fluid from wild type and mannose receptor knock-out littermate mice. This includes both an unchallenged mice and mice subjected to intratracheal LPS instillation to induce injury and inflammation.
Project description:CX3CR1pos monocytes are mobilized upon infection and undergo monocyte-to-macrophage transition in inflamed tissues. Using scRNA-seq of CD11c+ cells from bronchoalveolar lavage fluid (BALF) infected with IAV (PR/8, H1N1 ,we demonstrate that, during severe viral pneumonia, bone marrow-derived macrophages (BMDM) pass co-ordinated trajectories of pro-inflammatory-to-tissue-healing phenotypes, before differentiating into tissue-resident alveolar macrophages, that retain a long-term tissue-protective phenotype.