Type I and II Pneumocyte Differentiation in the Developing Fetal Chicken Lung: Conservation of Pivotal Proteins from Birds to Human in the Struggle for Life at Birth

Abstract

Background: Antenatal corticosteroids and surfactant replacement therapy have dramatically reduced mortality caused by lung disease in premature babies. Knowledge about mechanisms regulating epithelial differentiation of the respiratory membrane is limited, as are effects of pharmacological interventions. The chicken fetus is a valuable model for exploring pharmacological actions on developing organs. However, more precise information about the timing of developmental events in the chicken lung is needed for human correlation. Objectives: Characterization of morphological development and protein expression in the respiratory membrane of the developing chicken lung to create a platform for pharmacological testing in a human context. Methods: Fetal chicken lungs, embryonic days (E) 7-20, were characterized by morphology and protein expression of epithelial differentiation markers. This was compared with publications on the same processes during human lung development. Results: The respiratory membranes of developing chicken and human lungs show basic similarities. In chicken, surfactant protein B is expressed in cuboidal type II epithelial cells from E17. Aquaporin 5 is expressed in the epithelium from E7 and selectively in type I pneumocytes from E17. The type I pneumocyte and endothelial marker, caveolin 1, is expressed in the endothelium from E7 to E20. Conclusion: Despite phylogenetic distance, central aspects of cellular development in the chicken and human lung are similar. The fetal chicken model has important additional advantages to mammalian models, including fetal independence and short incubation, and is thus well suited for in vivo studies of lung maturation relevant to human development.

Expression of caveolin‐1 in the interfollicular but not the follicle‐associated epithelial cells in the bursa of fabricius of chickens

“…Cav‐1 is localized in the plasma membrane invaginations (caveolae), trans‐Golgi‐network (TGN), and vesicular structures of the cytoplasm (Goetz, Lajoie, Wiseman, & Nabi, ; Razani, Woodman, & Lisanti, ; Rothberg et al, ). Cav‐1 is a highly versatile molecule that is involved in diverse cellular and physiological functions (Feng, Guo, Han, & Li, ; Parton & Simons, ): intracellular cholesterol transport (Fielding & Fielding, ) cholesterol homeostasis (van Deurs, Roepstorff, Hommelgaard, & Sandvig, ; Fielding & Fielding, ; Frank et al, ; Liqing, Guoguang, Dezhi, & Kun, ; Martin & Parton, ; Razani et al, ), endocytosis (Brown & London, ; Huang et al, ; Kiss, ; Lajoie & Nabi, ; Le, Guay, Altschuler, & Nabi, ; Pelkmans & Helenius, ), cell migration (Navarro, Anand‐Apte, & Parat, ), cell differentiation (Bjørnstad, Paulsen, Erichsen, Glover, & Roald, ; Guan et al, ; Jung, Schlenz, Krasteva, & Mühlfeld, ; Parton & Simons, ; Ravid, Maor, Werner, & Liscovitch, ), cell polarity (Beardsley et al, ), signaling and mechanotransduction (Isshiki & Anderson, ; Razani et al, ; Rizzo, Sung, Oh, & Schnitzer, ; Shaul & Anderson, ; Simons & Toomre, ), transcytosis (van Deurs et al, ), and tumorigenesis (Goetz et al, ; Razani et al, ). Overexpression of caveolin results in increased cholesterol efflux (Fielding & Fielding, ).…”

“…The occurence of caveolae is tissue specific; large number of caveolae can be found in adipocytes (Guan et al, ; Razani et al, ), endothelial cells (van Deurs et al, ; Navarro et al, ), fibroblasts (Razani et al, ), type I pneumocytes (Bjørnstad et al, ; Jung et al, ), and smooth and skeletal muscles (Razani et al, ; Way & Parton, ), but caveolae are not detectable in neurons of the central nervous system and lymphocytes (Cameron, Ruffin, Bollag, Rasmussen, & Cameron, ; Fra, Williamson, Simons, & Parton, ). However, Cav‐1 immunoreactivity has been described in astrocytes and oligodendroglial cells (Cameron et al, ).…”

“…, cell differentiation (Bjørnstad, Paulsen, Erichsen, Glover, & Roald, 2014;Guan et al, 2016;Jung, Schlenz, Krasteva, & M€ uhlfeld, 2012;Parton & Simons, 2007;Ravid, Maor, Werner, & Liscovitch, 2006), cell polarity (Beardsley et al, 2005), signaling and mechanotransduction (Isshiki & Anderson, 1999;Rizzo, Sung, Oh, & Schnitzer, 1998;Shaul & Anderson, 1998;Simons & Toomre, 2000), transcytosis (van Deurs et al, 2003), and tumorigenesis (Goetz et al, 2008;. Overexpression of caveolin results in increased cholesterol efflux (Fielding & Fielding, 2001).…”

Long-Term Culture of Distal Airway Epithelial Cells Allows Differentiation Towards Alveolar Epithelial Cells Suited for Influenza Virus Studies

“…Here, we achieved efficient long-term growth of chicken DAECs and differentiation towards cells positive for SFTPA and AQP5, molecular markers of chicken pneumocytes. The localization of these molecular markers in vivo strongly suggests that they are epithelial cells of the parabronchi, the site of gas exchange in birds [ 52 , 53 ]. In contrast to human DAECs, chicken DAECs required the TGF-β receptor kinase inhibitor RepSox, not the Notch inhibitor DBZ to maintain proliferation, which closely resembles the signalling pathways activated in mammalian airway epithelial cells in vitro [ [54] , [55] , [56] ].…”

RNA-seq profiles of chicken type II pneumocyte in response to Escherichia coli infection

“…Chicken type II pneumocytes (CP II cells), belonging to squamous epithelial cells, serve as a dynamic barrier, which secretes surfactants and modulate lung immunity to decrease the infection of invading pathogens. Human type II alveolar epithelial cell (AEC II cells), similar to CP II cells, could present antigens to CD4 + T cells as well [10–15]. When bacteria invade, AEC II cells can secrete antibacterial peptides, cytokines and chemokines, in particular the interleukin (IL)-8, which activate and guide monocytes and macrophage migrate to the site of infection [16].…”