The complex architecture of the mammalian alveolus, has made it difficult to elucidate the balance of fluid secretion vs. absorption that characterizes the air-filled alveolar surface. Recent data from human alveolar Type 2 cells, utilizing novel "thin film" confocal microscopy, coupled with Ca(2+)(i), nucleotide release, and patch clamp studies, suggest that the physiology of fluid transport under air-filled conditions is substantially different from "flooded" conditions (in vivo flooded lung, Ussing chambers). Project III tests the hypothesis that the mammalian alveolus both absorbs and secretes fluid, and that the direction of fluid transport reflects signals contained in alveolar surface liquid, e.g., extracellular nucleotides. Project III will test this overarching hypothesis in four Specific Aims.
Specific Aim 1 tests the hypothesis that purinergic signaling regulates the direction of AT2 fluid transport via coordinate inhibition of ENaC and activation of CFTR that reside in separate apical membrane compartments.
Specific Aim 2 tests the hypothesis that regulation of secretory vs. absorptive functions can be characterized in novel single cell ATI assays.
Specific Aim 3 tests the hypothesis that CFTR is not the "only" secretory pathway in the alveolus, e.g., 'alternative Cl(-) channels'and passive forces are important.
Specific Aim 4 tests the hypotheses that: a) the intact alveolus in vivo balances active ion/water secretion and absorption;and b) that a fraction of the secreted liquid transits onto distal airway surfaces. The Project strategy is to build a knowledge base from studies of isolated AT2 cells and ATI cells with thin film confocal technologies, supplemented with novel single cell volume flow and conventional Ca(2+)(i), nucleotide release, and patch clamp technologies;then study the integrated alveolar physiology in vivo with complementary confocal and novel transgenic techniques to test whether data from isolated AT2/AT1 cells predict in vivo physiology. The overarching goal is to understand the regulation of the balance of liquids on alveolar surfaces in health, with an emphasis on purinoceptors, and utilize this information to design the necessary novel therapies to treat effectively pulmonary diseases with alveolar flooding as their main pathogenic feature.

Public Health Relevance

Major human diseases are characterized by excess alveolar surface liquid, i.e., pulmonary edema. These diseases include congestive left ventricular heart failure and acute respiratory distress syndromes (ARDS). Recent therapeutic trials of novel agents, e.g., inhaled 3 agonists, have been less successful than hoped. It is a goal of this PPG to provide information that will provide the framework and design of the novel therapeutic agents required to treat these life-threatening human diseases.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Program Projects (P01)
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Heart, Lung, and Blood Initial Review Group (HLBP)
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University of North Carolina Chapel Hill
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He, Lihua; Aleksandrov, Andrei A; An, Jianli et al. (2015) Restoration of NBD1 thermal stability is necessary and sufficient to correct ?F508 CFTR folding and assembly. J Mol Biol 427:106-20
Roy, Michelle G; Livraghi-Butrico, Alessandra; Fletcher, Ashley A et al. (2014) Muc5b is required for airway defence. Nature 505:412-6
Henderson, Ashley G; Ehre, Camille; Button, Brian et al. (2014) Cystic fibrosis airway secretions exhibit mucin hyperconcentration and increased osmotic pressure. J Clin Invest 124:3047-60
Esther Jr, Charles R; Boucher, Richard C; Johnson, M Ross et al. (2014) Airway drug pharmacokinetics via analysis of exhaled breath condensate. Pulm Pharmacol Ther 27:76-82
Donnelley, Martin; Morgan, Kaye S; Siu, Karen K W et al. (2014) Non-invasive airway health assessment: synchrotron imaging reveals effects of rehydrating treatments on mucociliary transit in-vivo. Sci Rep 4:3689
Cholon, Deborah M; Quinney, Nancy L; Fulcher, M Leslie et al. (2014) Potentiator ivacaftor abrogates pharmacological correction of ?F508 CFTR in cystic fibrosis. Sci Transl Med 6:246ra96
Bove, Peter F; Dang, Hong; Cheluvaraju, Chaitra et al. (2014) Breaking the in vitro alveolar type II cell proliferation barrier while retaining ion transport properties. Am J Respir Cell Mol Biol 50:767-76
Guo, Xueliang; Zheng, Shuo; Dang, Hong et al. (2014) Genome reference and sequence variation in the large repetitive central exon of human MUC5AC. Am J Respir Cell Mol Biol 50:223-32
Yang, Zhengrong; Wang, Chi; Zhou, Qingxian et al. (2014) Membrane protein stability can be compromised by detergent interactions with the extramembranous soluble domains. Protein Sci 23:769-89
Hill, David B; Vasquez, Paula A; Mellnik, John et al. (2014) A biophysical basis for mucus solids concentration as a candidate biomarker for airways disease. PLoS One 9:e87681

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