Effects of keratinocyte growth factor on intra‐alveolar surfactant fixed in situ: Quantitative ultrastructural and immunoelectron microscopic analysis

Abstract

Quantitative (immuno) transmission electron microscopy using design-based stereology was performed on specimens collected by means of systematic uniform random sampling of rat lungs, which were fixed by vascular perfusion to stabilize intra-alveolar surfactant in situ. This procedure ensures that the data recorded are representative of the whole organ. Ultrathin sections of specimens embedded at low temperature in Lowicryl HM20 were labeled by indirect immuno-gold staining for surfactant protein A. We observed that, 3 days after treatment of lungs in vivo with truncated keratinocyte growth factor (DN23-KGF), a potent mitogen of alveolar epithelial type II cells, surfactant protein A associated with the tubular myelin fraction of intra-alveolar surfactant was increased by 47% in comparison with buffer-treated control lungs. Despite the marked type II cell hyperplasia, the relative amount of ultrastructural surfactant subtypes was not significantly affected. Because surfactant protein A reduces the sensitivity to inhibition of the biophysical activity of surfactant by exudating plasma proteins, we propose that pretreatment of lungs with DN23-KGF ameliorates adverse effects observed in acute lung injury following, for example, ischemia and reperfusion. Anat Rec, 290:974-980, 2007. 2007 Wiley-Liss, Inc.

Protective effects of a bacterially expressed NIF–KGF fusion protein against bleomycin-induced acute lung injury in mice

“…When administered intratracheally, KGF acts as a potent mitogen of alveolar epithelial type II cells, and the production of surfactant protein A associated with the tubular myelin fraction of the intra-alveolar surfactant increased by 47% in comparison with buffer-treated control lungs. In contrast, intra-alveolar surfactant subtypes were not affected [20]. However, we found in our previous study that the analog can inhibit the proliferation of fibroblasts markedly in a dose-dependent manner (data not shown), consistent with results of Tang and Gilchrest [21].…”