猪肺表面活性蛋白A在急性肺损伤中的变化及其意义

 【目的】通过对猪血清和支气管肺泡灌洗液(BALF)中肺表面活性蛋白A(SP-A)含量的变化及其与反映肺损伤程度的指标－肺含水量变化的关系的研究,探讨猪SP-A在急性肺损伤(ALI)和兽医临床上诊治猪呼吸系统疾病(PRD)中的意义。【方法】选择50±1日龄的18头健康大白猪建立包含对照组(NS组)和油酸组(OA组)的油酸－急性肺损伤模型;取1、3和6 h时相点,分别用ELISA技术检测血清中SP-A含量、用Western blotting技术检测BALF中SP-A含量;血清中SP-A含量、BALF中SP-A含量与肺含水量两两变量间的相关性用Kendall相关分析法进行分析。【结果】与NS组相比,OA组的肺含水量在1、6 h时相点均显著增加(P＜0.05),在3 h时相点极显著增加(P＜0.01);在OA组中,3 h时相点肺含水量高于1 h时相点、6 h时相点肺含水量低于3 h时相点,但差异均不显著;推断在OA组3个时相点中,1 h时相点处于肺损伤前期,3 h时相点肺损伤较严重,6 h时相点位于肺损伤的缓解期。与NS组相比,在OA组的肺损伤前期,血清中SP-A含量极显著增加(P＜0.01),在OA组的肺损伤较严重时期和肺损伤缓解期,血清中SP-A含量高于NS组,但是与NS组差异均不显著;而OA组中,肺损伤较严重时期血清中SP-A含量比肺损伤前期极显著降低(P＜0.01),肺损伤缓解期血清中SP-A含量比肺损伤较严重时期显著降低(P＜0.05)。在肺损伤不同时期,OA组BALF中SP-A含量都极显著低于NS组(P＜0.01);在OA组中,肺损伤较严重时期与肺损伤前期相比,BALF中SP-A含量极显著降低(P＜0.01),肺损伤缓解期与肺损伤较严重时期相比,BALF中SP-A含量极显著增加(P＜0.01)。相关分析显示：血清中SP-A含量与肺含水量之间呈极显著正相关关系(r=0.50327,P＜0.01),BALF中SP-A含量与肺含水量之间呈极显著负相关关系(r=－0.72499,P＜0.0001)。【结论】由于SP-A 的表达具有非肺组织特异性,所以把猪血清中SP-A含量作为反映肺损伤程度的指标还有待进一步的研究;但是可以把BALF中SP-A含量作为急性肺损伤中反映猪肺损伤程度及其预后检测的重要指标之一。本研究为兽医临床上通过检测血清和BALF中SP-A含量诊治猪呼吸系统疾病以及开展相关研究奠定了基础。

Diversification of Porcine Pulmonary Surfactant Protein A and Its Significance in Acute Lung Injury

【Objective】 To discuss the significance of porcine pulmonary surfactant protein A (SP-A) in acute lung injury (ALI) and in veterinary clinical diagnoses and cure porcine respiratory disease (PRD), diversification of SP-A concentration in porcine serum and branchoalveolar lavage fluid (BALF), and relationship between the SP-A concentration and the changes of lung water content, which is the index of the severity of lung injury, was assessed. 【Method】 Eighteen healthy Large White piglets of 50±1 days were collected to establish a model of oleic acid (OA)-ALI containing normal saline (NS) group and OA group. At 1, 3, 6 h time point, the SP-A concentration in serum was measured by ELISA technology, and the SP-A concentration in BALF was measured by Western blotting technology, respectively. Also, the correlation between the SP-A concentration in serum and the lung water content, and between the SP-A concentration in BALF and the lung water content were studied by Kendall correlation analysis. 【Result】Compared with the NS group, porcine lung water content of OA group was significantly increased at 1, 6 h time point (P＜0.05), and was extremely significantly increased at 3 h time point. In OA group (P＜0.01), porcine lung water content at 3 h time point was higher than those at 1 h time point, and porcine lung water content at 6 h time point was lower than those at 3 h time point, but both of the difference was not significant. It was deduced that the 1 h time point fell into protophase of lung injury, lung injury was more severe at 3 h time point, and 6 h time point fell into paracmasis of lung injury. Compared with the NS group, the SP-A concentration in serum of OA group was extremely significantly increased in protophase of lung injury (P＜0.01), and that of OA group was higher than those of NS group in severe period and protophase of lung injury, but both of the difference wasn’t prominent. Moreover, the SP-A concentration in serum of OA group in severe period was extremely significantly reduced compared with those in protophase of lung injury (P＜0.01), and the SP-A concentration in serum of OA group in paracmasis was significantly reduced compared with those in severe period of lung injury (P＜0.05). During different periods of lung injury, the SP-A concentration in BALF of OA group was extremely significantly reduced compared with the NS group (P＜0.01). Moreover, the SP-A concentration in BALF of OA group in severe period was extremely significantly reduced compared with those in protophase of lung injury (P＜0.01), and the SP-A concentration in BALF of OA group in paracmasis was extremely significantly increased compared with those in severe period of lung injury (P＜0.01). Correlation analytic results showed that there was an extremely significantly positive correlation between lung water content and ELISA assaying for SP-A concentration in serum (r=0.50327, P＜0.01), and there was extremely significantly negative correlation between lung water content and Western blotting assaying for SP-A concentration in BALF (r=-0.72499, P＜0.0001). 【Conclusion】 As the expression of SP-A is not pulmonary tissue specific, there are still some further investigations left that porcine SP-A concentration in serum is taken as a marker for evaluation of the severity of lung injury. Porcine SP-A concentration in BALF could be taken as an index for evaluation of the severity and prognosis of lung injury during ALI. This research has established a primary foundation for clinical diagnoses and cure of PRD, and development of related research through assay for SP-A concentration in porcine serum and BALF.