Study On Protective Effects Of Keratinocyte Growth Factor On Acute Lung Injury Induced By Lipopolysaccharide In Rat

Objective:To observe the preventive effects of keratinocyte growth factor (KGF) on acute lung injury induced by lipopolysaccharide (LPS) in rat, which can be serve a new idea for prevent of acute lung injury (ALI) caused by LPS.Method:The experiment was divided into three parts.Part one:Study on effects of KGF on ALI induced by LPS. Eighteen male Sprague-Dawley rats were randomly divided into three groups of six. A was normal control group. B was ALI model group. B group rats were injected with LPS (6mg/kg) by caudal vein. C was KGF intervention group. C group rats were injected with a single intratracheal instillation does of KGF (5mg/kg) saline72h before injection. All of rats were killed in each group in8h after injection. To measure the arterial blood gas analyses and evaluate the pneumonedema by water content of lung and the ratios of wet lung tissue and dry lung tissue (W/D). The lung pathological changes were observed with microscope.Part two:Study on influences of KGF on cell biomarker of ALI induced by LPS Group of experiments was same as part one. Collected the lung tissue homogenate, conserved in-80refrigerator. The content of KL-6, AQP5and ACE were detected by Western Blot.Part three:Study on differences expression of microRNA of ALI induced by LPS Six SD rats were randomly divided into LPS group (n=3) and KGF group (n=3). LPS group rats were injected with LPS (6mg/kg) by caudal vein. KGF group rats were injected with a single intratracheal instillation does of KGF (5mg/kg) saline72h before injection. Total RNA was extracted from lung tissue and differential expression of miRNAs were detected by Phalanx miRNA OneArray. The obtained result was consistent with real-time-PCR analyses. Result:Part one:Compared with A group, PaO2, PaO2/FiO2were decreased in other groups(all P<0.01), compared with B group, PaO2,PaCO2and PaO2/FiO2in C group were improved significantly (all P<0.01). Compared with A group, the lung index in B and C groups were increased (all P<0.01). And C group was lower in W/D and water content of lung than B group (p<0.01). The alveolar wall tissue was thickened more significantly and a large amount of inflammatory cell were infiltrated beside fibrosis in B group. The lung pathological changes were obviously milder in C group.Part two:Compared with A group, the level of KL-6in lung tissue homogenates were remarkable increased (p<0.05), and the concentration in C group was higher than B group (p<0.05). Compared with A group, the level of AQP-5in lung tissue homogenates were significantly decreased (p<0.05). The level of AQP-5in lung tissue homogenates in C group was higher than B group, but the difference was not statistically significant (p>0.05). Compared with group A, the level of ACE in other lung tissue homogenates were increased significantly (p<0,05), C group than in group B in rat lung tissue ACE levels have decreased, but the difference between the two groups was not significant (p>0.05).Part three:The result of expression of miRNA in chips showed no dignificant difference between LPS group and KGF group. To predict the targets and function of miRNA by bioinformatics analysis and identified by real-time-PCR. The results showed that, compared with LPS group, miR-494was significantly up-regulated, miR-145and miR-146b was significantly down-regulated, the difference was statistically significant (p<0.01).Conclusion:1. The preventive effect of KGF against LPS-induced acute lung injury is identified. In the rats pretreated with KGF can significantly increase the PaO2, PaO2/FiO2, and lower PaCO2, lung wet-dry ratio and lung water content。 Stimulation of AT-Ⅱ proliferation is one of the mechanisms about KGF. 2. By promoting the AT-Ⅱ cell proliferation, increased the number of AT-Ⅰ cells, to maintain the integrity of the pulmonary vascular endothelial cells, KGF plays a protective role in lung injury.3. The expression of miR-494, miR-145and miR146b has significant changed in KGF group. These miRNAs are related to cell proliferation and anti-apoptosis. These miRNAs may be important points of regulation in prevention and treatment of lung injury induced by LPS.