泼尼松对IL-8在COPD大鼠肺组织表达的影响

目的 研究IL-8在慢性阻塞性肺病(COPD)大鼠肺组织中的表达及泼尼松对其表达的影响.方法 Wistar大鼠24只随机分为:正常对照组(A组)、单纯熏烟组(B组)和熏烟 泼尼松组(C组),每组各8只.单纯熏香烟法建立COPD模型,C组于熏香烟前予泼尼松5 mg/kg隔日灌胃.模型建立后,行支气管肺泡灌洗,测定支气管肺泡灌洗液(BALF)中细胞数,酶联免疫吸附法(ELISA)测定BALF上清液和血清中的IL-8和TNF-α浓度,并对肺组织切片行苏木精-伊红(HE)染色观察形态学改变,采用图像分析系统定量测定肺平均内衬间隔(MLI)、平均肺泡数(MAN)和肺泡腔面积与总面积比(PAA).结果 B组MLI、PAA比A组增高,而MAN低于A组,C组与B组相比MLI、PAA降低,MAN升高,差异均有统计学意义(P＜0.01).与A组比较,B组BALF中IL-8、TNF-α、白细胞总数、中性粒细胞绝对计数和中性粒细胞百分比均增高(P＜0.05),C组较B组上述指标均下降(P＜0.05).B组血清中IL-8和TNF-α浓度亦比A组增高(P＜0.05),C组较B组下降,但IL-8的浓度差异无统计学意义.B组BALF中IL-8与中性粒细胞绝对计数、TNF-α呈正相关(r=0.735、0.987,P＜0.05);与血清中IL-8和TNF-α、血气分析的所有指标及形态学定量分析的任一指标均无相关性.血清IL-8与上述任一指标亦均无相关性.结论 BALF中的IL-8与COPD的气道炎症密切相关,IL-8与TNF-α相互作用,通过趋化激活中性粒细胞等炎性细胞共同参与COPD发病.泼尼松可能通过抑制IL-8的表达,从而减轻炎症介质和炎性细胞对气道的损害,延缓COPD的进展.

The Effect of Glucocorticoid on IL-8 Expressing in Lung Tissue of Rat with Chronic Obstructive Pulmonary Disease

OBJECTIVE: To explore the role of IL-8 in the pathogenesis of chronic obstructive pulmonary disease (COPD) and the effect of glucocorticoid on COPD. METHODS: 24 health males of Wistar rats were randomly divided into three groups (group A: normal control group, group B: COPD model group, group C: group pretreated with prednisone), of which each got 8 rats for this study project. Rat COPD model was established by exposing rat to cigarette smoke daily for 120 days. The prednisone was, via stomachal injection, given to the rats of group C with a dose of 5 mg/kg on every other day just before rats exposed to cigarette smoke. After COPD model was set up, the bronchoalveolar lavage (BAL) was performed. The total cells and neutrophils in bronchoalveolar lavage fluid (BALF) were counted for examination, and the levels of IL-8 and TNF-alpha in supernatants of BALF and serum were detected by ELISA. The lung tissue section stained by HE was observed in order to study the alternation of morphology, and also measured in terms of mean lining interval (MLI), mean alveolus number (MAN) and percentage of alveolar area in total area (PAA). RESULTS: MLI and PAA in group B were higher than those in group A (P < 0.01), and decreased after pretreatment with prednisone (P < 0.01), in which however MAN was just on the contrary. The statistic analysis showed that levels of IL-8 [(114.5 +/- 15.7) pg/mL vs (259.4 +/- 20.1) pg/mL, respectively, P < 0.01], TNF-alpha [(80.5 +/- 9.5) pg/mL vs (145.9 +/- 17.3) pg/ mL, P < 0.01], total cell counts [(1.64 +/- 0.12) x 10(8)/L vs (5.76 +/- 0.29) x 10(8)/L, P < 0.01], neutrophil counts [(0.099 +/- 0.065) x 10(8)/L vs (1.26 +/- 0.25) x 10(8)/L P < 0.01], neutrophil proportion [(5.9 +/- 3. 6)% vs (21.8 +/- 3.7)%, P < 0.05] in BALF of group B were higher than those of group A. After pretreatment with prednisone, the above measured values were significant reduction (P < 0.01 or 0.05). The level of IL-8 in serum of group B was higher than that of group A [(45.2 +/- 13.5) pg/mL vs (85.7 +/- 7.0) pg/mL, P < 0.01], but which, after pretreatment, there was reduction but no significance (P > 0.05). The positive correlation was demonstrated among the levels of IL-8, TNF-alpha and counted neutrophils in BALF of group B, but not between the level of IL-8 and TNF-alpha in serum. CONCLUSION: There is a close correlation between IL-8 in BALF and airway inflammation with COPD. The IL-8 cooperating with TNF-alpha may be responsible for the persistence and amplification of airway inflammation with COPD. By modulating the expression of IL-8 gene, inhibiting granulocyte chemotaxis and degranulation, the prednisone may relieve airway inflammation, and relieve the lesion of airway resulting from inflammatory cytokines and cells, hence postpone the progress of COPD.