Expression of CINC-2β Is Related to the State of Differentiation of Alveolar Epithelial Cells

Alveolar epithelial cells are among the first cells to encounter inhaled particles or organisms. These cells likely participate in the initiation and modulation of the inflammatory response by production of chemokines. However, there is little information on the extent or regulation of chemokine production by these cells. Rat type II cells were studied under differentiated and dedifferentiated conditions to determine their ability to express and secrete CXC chemokines. Both differentiated and dedifferentiated type II cells secreted MIP-2, MCP-1, and CINC-2 in response to a cytokine mixture of IL-1β, TNF-α, and IFN-γ or to IL-1β alone. The cytokine mixture also induced iNOS expression and nitrite secretion. Both differentiated and dedifferentiated type II cells expressed CINC-1 (GRO), CINC-2α, CINC-3 (MIP-2), and MCP-1 mRNA, and their expression was increased by the cytokine mixture or by IL-1β alone. However, CINC-2β, a splice variant of CINC-2, was only expressed under differentiated conditions stimulated by KGF and was not increased by the cytokine mixture or by IL-1β. In situ hybridization of normal lung and lung instilled with Ad-KGF demonstrated that CINC-2β was expressed by alveolar and bronchiolar epithelial cells in vivo. We conclude that CINC-2β is regulated differently from most other chemokines and that its expression is related to the state of alveolar type II cell differentiation

Differentiated human alveolar epithelial cells and reversibility of their phenotype in vitro

Cultures of differentiating fetal human type II cells have been available for many years. However, studies with differentiated adult human type II cells are limited. We used a published method for type II cell isolation and developed primary culture systems for maintenance of differentiated adult human alveolar epithelial cells for in vitro studies. Human type II cells cultured on Matrigel (basolateral access) or a mixture of Matrigel and rat tail collagen (apical access) in the presence of keratinocyte growth factor, isobutylmethylxanthine, 8-bromo-cyclicAMP, and dexamethasone (KIAD) expressed the differentiated type II cell phenotype as measured by the expression of surfactant protein (SP)-A, SP-B, SP-C, and fatty acid synthase and their morphologic appearance. These cells contain lamellar inclusion bodies and have apical microvilli. In both systems the cells appear well differentiated. In the apical access system, type II cell differentiation markers initially decreased and then recovered over 6 d in culture. Lipid synthesis was also increased by the addition of KIAD. In contrast, type II cells cultured on rat tail collagen (or tissue culture plastic) slowly lose their lamellar inclusions and expression of the surfactant proteins and increase the expression of type I cell markers. The expression of the phenotypes is regulated by the culture conditions and is, in part, reversible in vitro

TGF beta inhibits HGF, FGF7, and FGF10 expression in normal and IPF lung fibroblasts

TGF beta is a multifunctional cytokine that is important in the pathogenesis of pulmonary fibrosis. The ability of TGF beta to stimulate smooth muscle actin and extracellular matrix gene expression in fibroblasts is well established. In this report, we evaluated the effect of TGF beta on the expression of HGF, FGF7 (KGF), and FGF10, important growth and survival factors for the alveolar epithelium. These growth factors are important for maintaining type II cells and for restoration of the epithelium after lung injury. Under conditions of normal serum supplementation or serum withdrawal TGF beta inhibited fibroblast expression of HGF, FGF7, and FGF10. We confirmed these observations with genome wide RNA sequencing of the response of control and IPF fibroblasts to TGF beta. In general, gene expression in IPF fibroblasts was similar to control fibroblasts. Reduced expression of HGF, FGF7, and FGF10 is another means whereby TGF beta impairs epithelial healing and promotes fibrosis after lung injury.TGF beta inhibits the important growth factors HGF, FGF7, and FGF10. This inhibition may be a very important component for the development of pulmonary fibrosis. Control and IPF fibroblasts were inhibited similarly.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145584/1/phy213794_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145584/2/phy213794.pd