Ⅱ类主要组织相容性抗原在博来霉素致大鼠纤维化肺组织中的表达

Expression of major histocompatibility complex class Ⅱ antigens on lungs in rat with bleomycin-induced pulmonary fibrosis

目的:在博来霉素诱导的大鼠肺纤维化模型上,观察主要组织相容性复合体(major histocompatibility complex,MHC)Ⅱ类分子及其上游调控因子Ⅱ类反式激活蛋白(classⅡtransactivator,CⅡTA)表达水平的变化,探索肺纤维化发病可能的免疫机制。方法:在大鼠气管内灌注博来霉素(纤维化组)或生理盐水(对照组),分别于第7、第28天处死大鼠,取大鼠肺组织行HE染色和Masson染色,用生化法测定肺组织羟脯氨酸含量,免疫组化SP法染色观察肺组织MHCⅡ类分子表达,利用Taqman探针方法实时PCR(real-time PCR)技术测定肺组织总CⅡTA及Ⅰ型、Ⅲ型、Ⅳ型CⅡTA mRNA表达。结果:(1)第7、第28天时纤维化组肺组织MHCⅡ阳性细胞百分比均较对照组增加[(0.10±0.03)vs(0.06±0.02),P<0.05;(0.15±0.03)vs(0.06±0.01),P<0.01];纤维化组第28天较第7天增加[(0.15±0.03)vs(0.10±0.03),P<0.05];(2)第7天时,纤维化组大鼠肺组织总CⅡTA较对照组升高170.4%[(2.89±1.07)vs(1.07±0.46),P<0.05],Ⅰ型CⅡTA较对照组升高258.8%[(0.77±0.38)vs(0.21±0.09),P<0.05],Ⅳ型CⅡTA较对照组降低87.2%[(0.39±0.15)vs(3.01±0.79),P<0.01];第28天时,纤维化组大鼠肺组织总CⅡTA较对照组升高98.6%[(4.14±1.15)vs(2.08±0.76),P<0.05],Ⅰ型CⅡTA较对照组升高137.1%[(0.79±0.34)vs(0.33±0.23),P<0.05],Ⅳ型CⅡTA仍较对照组低,但差异无统计学意义[(2.98±0.92)vs(3.95±0.93),P>0.05]。其中,纤维化组肺组织Ⅳ型CⅡTA在第28天时较第7天时升高667.3%[(2.98±0.92)vs(0.39±0.15),P<0.01]。Ⅲ型CⅡTA在各时期与对照组比较差异均无统计学意义。结论:肺组织MHCⅡ/CⅡTA体系参与了博来霉素诱导的肺纤维化的病理生理过程。

Objective：To explore the expression levels of MHC Ⅱ molecules and its regulator genes CⅡTA on bleomycin-induced pulmonary fibrosis in rats, and to investigate the underlying immunologic mechanisms of pulmonary fibrosis. Methods：The rats were treated with either a single intratracheal bleomycin injection （fibrosis group） or a normal saline injection （control group）. The pathologic changes of lung tissues stained with HE and Masson were observed, and the contents of hydroxyproline were detected on the 7th and 28th day respectively after bleomycin administration. The expression of MHC Ⅱ molecules in the lung tissues was evaluated with immunohistochemistry techniques, and the percentage of MHC Ⅱ＋ cells was measured. The amounts of total CⅡTA and typeⅠ,Ⅲ and Ⅳ CⅡTA mRNA of lung tissues were measured by real-time PCR using Taqman probe. Results： （1） The percentage of MHC Ⅱ ＋ cells in lung tissues increased significantly in fibrosis group compared with that of control group on the 7th day and the 28th day [（0.10±0.03） vs （0.06±0.02）, P〈0.05; （0.15±0.03） vs（ 0.06±0.01 ）,P〈0.01, respectively]; In fibrosis group, the percentage on the 28th day was higher than that on the 7th day [（0.15 ±0.03） vs （0.10±0.03）,P〈0.05] ; （2） Compared with control group on the 7th day, total CⅡTA mRNA increased 170. 4% [（2.89±1.07） vs （1.07±0.46）, P 〈0.05], typeⅠ CⅡTA increased 258.8% [（0.77±0.38） vs （0.21±0.09）, P 〈0.05], while type Ⅳ CⅡTA decreased 87.2% [ （0. 39±0. 15 ）vs （3.01±0.79）, P 〈0.01] ; On the 28th day, total CⅡTA mRNA increased 98.6% [ （4. 14±1.15 ）vs（2.08±0.76）, P 〈0. 051, type Ⅰ CⅡTA increased 137. 1% [（0.79±0. 34） vs （0.33±0.23）, P〈0.05], type Ⅳ CⅡTA mRNA still decreased, but there was no significant difference [（2. 98±0.92） vs （3.95±0.93 ）, P 〉 0. 05 ] ; In fibrosis group, type IV CⅡTA mRNA was 667.3% [（2.98±0.92 ）vs （0.39±0.15）, P〈0.01] higher on the 28th day than that on the 7th day; Type Ⅲ CⅡTA mRNA levels of both groups had no significant difference. Conclusion： MHC Ⅱ / CⅡTA system of lung tissues was probably involved in the development of rat pulmonary fibrosis.