Keratinocyte growth factor-induced hyperplasia of rat alveolar type II cells in vivo is resolved by differentiation into type I cells and by apoptosis

Abstract

Keratinocyte growth factor (KGF) is a potent mitogen of alveolar epithelial type II cells (AEII). AEII hyperplasia is resolved within several days following intratracheal instillation of KGF by unknown mechanism(s).AEII hyperplasia was induced in rat lungs by intrabronchial instillation of 5 mg recombinant human (rh)KGF . kg body weight -1 or an equivalent amount of diluent. Epithelial architecture, cell proliferation, transformation of AEII into type I cells (AEI) and apoptosis were investigated by means of immunohistochemistry, stereology, double immunofluorescence microscopy, electron microscopy and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) technique in lungs fixed 1, 2, 3 and 7 days after treatment.After 1 day of rhKGF instillation, an increase was observed in the nuclear antigen Ki-67, a proliferation marker detected by the antibody MIB-5-expressing surfactant protein (SP)-B, -C, -D-positive AEII. The incidence of mitosis was increased by day 2, resulting in AEII micropapillae with intense basolateral expression of the exon 6 containing isoform (v6) of CD446 (CD44v6), a marker for AEII. By day 3, monolayers of AEII exhibiting lateral CD44v6 covered 45% of the alveolar surface. After 7 days, there were numerous intermediate AEII/AEI cells characterized by a flat elongated shape, staining for SP-D, apical appearance of AEI marker Lycopersicon esculentum lectin and lateral staining for AEII marker CD44v6. Increased numbers of TUNELpositive epithelial cells were seen at days 2±7.In conclusion, restoration of normal alveolar epithelium after instillation of recombinant human keratinocyte growth factor is accomplished by terminal differentiation and apoptosis of hyperplastic alveolar epithelial type II cells in vivo. Eur Respir J 1999; 14: 534±544ol. Keratinocyte growth factor (KGF) is a heparin-binding stroma-derived member of the fibroblast growth factor family which selectively or at least predominantly stimulates the proliferation of epithelial cells [1±4]. In the lung, KGF has been demonstrated to act as a potent mitogen of alveolar epithelial type II cells (AEII) in vitro [5±7] and in vivo [8,9]. Studies of the kinetics of the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into alveolar cells showed that hyperplasia of AEII peaks at~2±3 days after treatment with recombinant human (rh)KGF given via the bronchial [8] or vascular route of administration [9]. At the time of AEII hyperplasia, the lungs are protected against various forms of injury including acid instillation [10], a-naphthylthiourea [11], hyperoxia [9], bleomycin [9, 12±14], and c-irradiation [12]. In these experiments, the animals were pretreated with rhKGF before the injury, and attempts at post-treatment have not been successful to date [13]. Consequently, the prevention of cell loss has been proposed to be an important mechanism by which rhKGF realizes this high protective potential [14].Although it has been reported that, 1 week after intratracheal treatment with rhKGF...

Alveolar macrophages are the main source for tumour necrosis factor‐α in patients with sarcoidosis

“…Serial sections of transbronchial biopsies obtained from the same patients during diagnostic bronchoscopy were analysed by standard IHC for TNF-a [20,21]. The staining pattern was correlated with IHC patterns for markers of T-cells (CD3), macrophages (CD68), and epithelial cells (cytokeratin: MNF116).…”

HTII-280, a Biomarker Specific to the Apical Plasma Membrane of Human Lung Alveolar Type II Cells

“…Although various proteins have been associated with TII cells, such as surfactant-associated proteins [of which surfactant protein (SP) C is specific for TII cells (Kalina et al 1992)], ATP-binding cassette sub-family A member 3 (Inagaki et al 2004), CD44v6 [expressed on the basolateral membrane of TII cells (Fehrenbach et al 1999)], pepsinogen C (Foster et al 2004), lysosome-associated membrane glycoprotein 3 (Salaun et al 2003), and E-cadherin (Kasper et al 1995), these are expressed intracellularly or are not TII cell specific. Although a TII cell-specific surface antigen has been described for the rat (Gonzalez and Dobbs 1997;Boylan et al 2001) and has been useful for evaluation of lung injury (Clegg et al 2005) and for isolating rodent TII cells (Gonzalez et al 2005(Gonzalez et al ,2009, to our knowledge, an apical plasma membrane marker specific to human TII cells has not been described in detail to date.…”

Therapeutic effect of lung mixed culture-derived epithelial cells on lung fibrosis

“…Similarly, LMDECs can be harvested at least two times from the same dish. After harvesting LMDECs from mixed culture at 9 DIV, the dishes were further incubated for 7-10 days (16)(17)(18)(19), and the round cells floating or loosely attached to the adherent cells appeared again. The yield of round cells was reduced by 10% compared with that at 9 DIV.…”

“…AEC II are generally characterized by expression of SP-C, and are accepted to be the progenitor cell population for the alveolus. 19 Differentiation of various stem cells into lung epithelial lineage-specific cells before administration into the injured lung is considered to enhance engraftment efficiency and the integrity of the alveolar epithelium. 2,20,21 Indeed, it has been reported that isolated AEC II have a potent regenerative effect on BLM-induced lung fibrosis, 22 but one of the problems in using AEC II is their isolation efficiency.…”