Effect of proinflammatory cytokines on growth factor expression of type n alveolar epithelial cells from neonate piglet lungs / 中国小儿急救医学

ABSTRACT

Objective To establish a method of isolation, purification and identification of type Ⅱ alveolar epithelial cells (AEC- K ) from neonate piglet lungs of 1 ～ 3 days old and to investigate effects of proinflammatory cytokines on expression of growth factors (GFs). The yield, viability and purity of AEC- Ⅱ obtained using different enzyme digestion and purifying methods were compared. Methods After the first 24-hour culture of AEC- Ⅱ ,the media containing interleukin (IL)-1β,IL-6 and IGF-Ⅰ at different concentrations were used to culture AEC-Ⅱ for another 48 hours. And then the cells were counted and the expressions of insulin-like growth factor (IGF-Ⅰ ), platelet-derived growth factor ( PDGF), surfactant proteins (SP) -A and SP-B mRNA were determined by real time PCR. Results A significantly higher yield of AEC-Ⅱ was achieved by digesting the lung with 30 unit/ml elastase and 0.1 % trypsin at 37 t for 20 min, the yield was (5.33 ±0.54) × 106 after adjusted by the weight of lung and heart (P <0.01). The number of purified AEC-II obtained by immune adherence method was (38.0 ±28.0) × 106 perpiglet which was higher than by the method of percoll. The optimal phenotype maintenance time of AEC- Ⅱ was the first 24～96 hours in the primary culture. With increasing concentrations of IL-1 β and IL-6, there were decreased proliferation and expression of SP-A and IGF-Ⅰ mRNA in the cultured AEC- Ⅱ ,but SP-B mRNA expression was not affected. Both AEC-Ⅱ proliferation and expression of SP-A, SP-B mRNA decreased significantly after cultured with anti-IGF-Ⅰ. Conclusion In a new model of cultured AEC-Ⅱ from neonate piglets, IL-1β and IL-6 inhibited AEC- Ⅱ proliferation and SP-A mRNA expression through IGF-Ⅰ -dependent mechanisms.