Keratinocyte growth factor accelerates compensatory growth in the remaining lung after trilobectomy in rats

Serial changes in proliferating cell nuclear antigen (PCNA)–positive alveolar epithelial cell counts in the remaining lung. A-F, Immunohistochemical staining for PCNA. (Original magnification 400×.) Bar = 50 μm. A, Alveolar part of normal lung. B, Bronchial part of normal lung. C, Alveolar part at day 4 after trilobectomy. D, Bronchial part at day 4 after trilobectomy. E, Alveolar part at day 4 after the sham operation. F, Bronchial part at day 4 after the sham operation. G, Serial changes in proliferating cell nuclear antigen labeling index. Open circles, Trilobectomy group (n = 3); filled circles, sham group (n = 3). ^∗P < .05.

Western blot analysis of keratinocyte growth factor and keratinocyte growth factor receptor in the remaining lung. Recombinant human keratinocyte growth factor protein (lane 1) and lysates of remaining lung at day 4 after trilobectomy (lane 2) and after the sham operation (lane 3) are shown. Recombinant human keratinocyte growth factor receptor protein (lane 4) and lysates of remaining lung at day 4 after trilobectomy (lane 5) and after the sham operation (lane 6) are also shown.

Immunohistochemical detection of keratinocyte growth factor and keratinocyte growth factor receptor in the remaining lung after trilobectomy. The expression of keratinocyte growth factor (A, B, and E) and keratinocyte growth factor receptor (C, D, and F) was detected by means of immunohistochemistry. A, Alveolar part at day 4 after trilobectomy. B, Alveolar part at day 4 after the sham operation. C, Alveolar part at day 4 after trilobectomy. D, Alveolar part at day 4 after the sham operation. E, Bronchial part at day 4 after trilobectomy. F, Bronchial part at day 4 after trilobectomy (Original magnification 400×.) Bar = 50 μm. G, Serial changes in the signal density of keratinocyte growth factor staining in the trilobectomy group (n = 3, open circles) and the sham operation group (n = 3, filled circles). H, Serial changes in the signal density of keratinocyte growth factor receptor staining in the trilobectomy group (n = 3, open circles) and the sham operation group (n = 3, filled circles).

Immunohistochemical detection of keratinocyte growth factor, keratinocyte growth factor receptor, and proliferating cell nuclear antigen in serial sections of the remaining lung at day 4 after trilobectomy. A, Hematoxylin and eosin staining. B, Keratinocyte growth factor was detected in the cytoplasm of alveolar epithelial cells. C, Proliferating cell nuclear antigen staining. D, Keratinocyte growth factor receptor was detected in the plasma membrane of alveolar epithelial cells. Proliferating cell nuclear antigen–positive alveolar type II cells are identical, at least in part, to keratinocyte growth factor and keratinocyte growth factor receptor double-positive cells (arrows). Bar = 25 μm.

Keratinocyte growth factor protein production, DNA synthesis, and cell proliferation in cell medium and lysate transfected with the pKGF–FLAG gene and the pFLAG gene. A, The concentrations of keratinocyte growth factor in the medium and lysates of L2 cells transfected with the pKGF–FLAG gene and the pFLAG gene were measured at 24, 48, and 72 hours after transfection. The keratinocyte growth factor concentration in the medium of L2 cells transfected with the pKGF–FLAG gene increased in a time-dependent manner. B and C, DNA synthesis (B) and cell proliferation (C) of L2 cells transfected with pKGF–FLAG and pFLAG. L2 cells were transfected by means of electroporation; cultured for 24, 48, and 72 hours; and subsequently assessed for bromodeoxyuridine uptake, as well as the number of cells per well. There were significant differences in bromodeoxyuridine uptake between the pKGF–FLAG gene and the pFLAG gene at 24 and 48 hours after transfection. There was also a significant difference in the cell numbers between the pKGF–FLAG gene and the pFLAG gene at 72 hours after transfection.

Effects of pKGF–FLAG gene and pFLAG gene expression on proliferating cell nuclear antigen (PCNA)–positive cells at day 4 after electroporative transfection. A and B, Immunohistochemistry for proliferating cell nuclear antigen in the alveolar part of the remaining lung transfected with the pFLAG gene (A) or the pKGF–FLAG gene (B). C and D, In adjacent sections of the alveolar part transfected with the pKGF–FLAG gene, one section (C) was used for the detection of FLAG (KGF–FLAG), and another (D) was stained for proliferating cell nuclear antigen expression. (Original magnification 400×.) Bar = 50 μm. E, Serial changes in proliferating cell nuclear antigen labeling index. Open bars, Group transfected with the pFLAG gene (n = 5); filled bars, group transfected with the pKGF–FLAG gene (n = 5). ^∗P < .05. F, Mean linear intercept values measured in the remaining lung transfected with the pFLAG gene or the pKGF-FLAG gene. Values are presented as means ± standard error of the mean. ^∗P < .001 for comparison of mean linear intercept of the remaining lung transfected with the pKGF–FLAG gene and that with the pFLAG gene.

Double staining for proliferating cell nuclear antigen and surfactant protein-A at day 4 after transfection in the alveolar part of the remaining lung transfected with the pKGF–FLAG gene. Double staining for proliferating cell nuclear antigen (blue) and surfactant protein-A (brown). The majority of proliferating cell nuclear antigen–positive cells were epithelial cells. Arrows, Alveolar type II cells; arrowhead, type I cells. (Original magnification 400×). Bar = 25 μm.