吉林大学学报(医学版)  2019, Vol. 45 Issue (02): 342-346     DOI: 10.13481/j.1671-587x.20190222

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毕红东, 谢亚芹, 崔海鹏, 刘凯, 孙晓旭, 王途, 赵娟
BI Hongdong, XIE Yaqin, CUI Haipeng, LIU Kai, SUN Xiaoxu, WANG Tu, ZHAO Juan
多肽化合物urantide对动脉粥样硬化大鼠胸主动脉和VSMC中Ⅳ型胶原表达的影响
Effects of urantide on expressions of type Ⅳ collagenin thoracic aorta and VSMC of atherosclerotic rats
吉林大学学报(医学版), 2019, 45(02): 342-346
Journal of Jilin University (Medicine Edition), 2019, 45(02): 342-346
10.13481/j.1671-587x.20190222

文章历史

收稿日期: 2018-06-04
多肽化合物urantide对动脉粥样硬化大鼠胸主动脉和VSMC中Ⅳ型胶原表达的影响
毕红东 , 谢亚芹 , 崔海鹏 , 刘凯 , 孙晓旭 , 王途 , 赵娟     
承德医学院基础医学部, 河北 承德 067000
[摘要]: 目的: 探讨多肽化合物urantide对动脉粥样硬化(AS)大鼠胸主动脉和血管平滑肌细胞(VSMC)中Ⅳ型胶原(Col Ⅳ)表达的影响,阐明其防治AS的作用机制。方法: 180只Wistar大鼠随机分为正常对照组(n=30)和AS模型组(n=150),采用高脂饲料喂养和腹腔注射维生素D3(VD3)的方法建立大鼠AS模型。150只AS模型鼠随机分为AS组、氟伐他汀(Flu)组和urantide组(3、7和14 d组)(n=30)。免疫组织化学法检测大鼠胸主动脉壁内Col Ⅳ的表达水平,酶联免疫吸附试验(ELISA)法检测大鼠血清和尿液中羟脯胺酸(HYP)水平。体外培养的VSMC随机分为正常对照组、尾加压素(UⅡ)(10-8 mol·L-1)组、Flu组和urantide(10-10~10-6 mol·L-1)组,ELISA法检测各组大鼠VSMC培养上清中Col Ⅳ水平。结果: 各组大鼠胸主动脉内膜下不规则斑块内Col Ⅳ表达水平比较差异有统计学意义(F=35.09,P < 0.01)。与正常对照组比较,AS组大鼠主动脉中Col Ⅳ表达水平明显升高(P < 0.01);urantide组Col Ⅳ阳性染色强度和范围较AS组均减少(P < 0.01)。各组大鼠血清和尿液中HYP水平比较差异有统计学意义(F=24.38,P < 0.01;F=26.72,P < 0.01)。与正常对照组比较,AS组大鼠血清中HYP水平明显升高(P < 0.01),尿液中HYP水平明显降低(P < 0.01);与AS组比较,urantide组大鼠血清中HYP水平均明显降低(P < 0.01),尿液中HYP水平明显升高(P < 0.01),接近或优于Flu组水平。各组大鼠VSMC培养上清中Col Ⅳ水平比较差异有统计学意义(F=31.04,P < 0.01)。与正常对照组比较,UⅡ组大鼠VSMC培养上清中Col Ⅳ水平明显升高(P < 0.01);与UⅡ组比较,urantide组大鼠VSMC培养上清中Col Ⅳ水平明显降低(P < 0.05或P < 0.01)。结论: urantide可抑制AS大鼠胸主动脉和VSMC中Col Ⅳ的表达,缓解AS病变程度,为临床应用urantide治疗AS提供了实验依据。
关键词: 动脉粥样硬化    尾加压素Ⅱ    urantide    胸主动脉    血管平滑肌细胞    Ⅳ型胶原    
Effects of urantide on expressions of type Ⅳ collagenin thoracic aorta and VSMC of atherosclerotic rats
BI Hongdong , XIE Yaqin , CUI Haipeng , LIU Kai , SUN Xiaoxu , WANG Tu , ZHAO Juan     
School of Basic Medical Sciences, Chengde Medical University, Chengde 067000, China
[ABSTRACT]: Objective: To investigate the effects of urantide on the expressions of type Ⅳ collagen(Col Ⅳ) in thoracic aorta and vascular smooth muscle cells(VSMC) in the rats with atherosclerosis(AS), and to clarify its mechanism of prevention and treatment of AS. Methods: A total of 180 Wistar rats were randomly divided into normal control group (n=30) and AS model group (n=150).The rat models of AS were established by feeding on high-fat diet or intraperitoneally injecting vitamin D3(VD3).The AS model rats were randomly divided into AS group, fluvestation(Flu) group and urantide group (3, 7, and 14 d groups).The expression of Col Ⅳ in thoracic aorta wall of the rats was detected by immunohistochemistry.The levels of hydroxyproline (HYP) in serum and urine of the rats in various groups were measured by ELISA.The VSMC were randomly divided into normal control group, urotensin Ⅱ(UⅡ 10-8mol·L-1) group, Flu group and urantide (10-10 to 10-6 mol·L-1) groups.The levels of Col Ⅳ in VSMC of the rats in various groups were determined by ELISA. Results: There was a significant difference in the expression levels of Col Ⅳ in the irregular plaques of the thoracic aorta of the rats between various groups (F=35.09, P < 0.01). The expression levels of Col Ⅳ in thoracic aorta of the rats in AS group were significantly increased compared with normal control group (P < 0.01); the intensity and extent of Col Ⅳ positive staining in urantide group were lower than those in AS group (P < 0.01).There were significant differences in the serum and urine HYP levels between various groups (F=24.38, P < 0.01;F=26.72, P < 0.01). Compared with normal control group, the serum HYP level of the rats in AS group were significantly increased (P < 0.01), and the urine HYP level was significantly decreased (P < 0.01).Compared with AS group, the serum HYP levels in urantide groups were significantly decreased (P < 0.01) and the urine HYP levels were significantly increased (P < 0.01), no less than the level in Flu group.The expression levels of Col Ⅳ in the culture supernatant of VSMC in the rats in various groups had significantly difference (F=31.04, P < 0.01).The expression level of Col Ⅳ in the culture supernatant of VSMC of the rats in UⅡ group was significantly increased compared with normal control group (P < 0.01); the expression levels of Col Ⅳ in the culture supernatant of VSMC of the rats in urantide groups were significantly decreased compared with UⅡ group(P < 0.05 or P < 0.01). Conclusion: Urantide can inhibit the expressions of Col Ⅳ in the thoracic aorta and VSMC of the AS rats and alleviate the degree of AS lesions, which provides the experimental evidence for the clinical application of urantide in the treatment of AS.
KEYWORDS: atherosclerosis     urotensinⅡ     urantide     vascular smooth muscle cells     type Ⅳ collagen          

Ⅳ型胶原(type Ⅳ collage, Col Ⅳ)是胶原性氨基酸,是由3条α肽链组成的三聚体结构,每条α链约含1 700个氨基酸残基,呈网状分布在组织中,其在动脉粥样硬化(atherosclerosis, AS)中的作用已成为研究的热点[1-2]。氧化应激导致的AS斑块破裂可促进主动脉平滑肌细胞中Col Ⅳ水平的增加[3]。研究[4-5]发现:在AS斑块形成中,经修饰的Col Ⅳ与低密度脂蛋白的氧化有关,可能导致内皮功能的障碍,参与AS的发生发展。多肽化合物urantide是血管活性物质尾加压素Ⅱ(urotensinⅡ, UⅡ)的受体拮抗剂,其拮抗效应较其他化合物高100倍[6-8]。本文作者前期研究[9]显示:urantide能竞争性拮抗UⅡ对AS大鼠胸主动脉的炎症损伤作用及对血管平滑肌细胞(vascular smooth muscle cells, VSMC)的促丝裂作用,抑制AS的发生发展,但具体作用机制尚未阐明。有关urantide对AS大鼠胸主动脉Col Ⅳ代谢影响的有关研究尚未见报道。本研究通过探讨多肽化合物urantide对AS大鼠Col Ⅳ表达的影响,阐明其防治AS的作用机制,为临床应用urantide治疗AS提供实验依据。

1 材料与方法 1.1 实验动物、主要试剂和仪器

SPF级雄性Wistar大鼠,体质量180~200 g,北京维通利华实验动物有限公司提供,实验动物使用许可证号:SCXK(京)-2016-0011,生产合格证号:11400700127208。urantide由苏州强耀生物公司提供,氟伐他汀(fluvastatin, Flu)购自北京诺华制药有限公司,DMEM培养基干粉和胎牛血清购自美国Gibco公司,Col Ⅳ(ELISA)试剂盒和羟脯胺酸(hydroxyproline, HYP)试剂盒购自江苏晶美生物科技有限公司,Col Ⅳ(小鼠抗大鼠)单克隆抗体购自美国RD公司,生物素标记二抗IgG、S-ABC试剂盒和DAB试剂盒购自碧云天生物技术有限公司。全自动封闭组织脱水机、包埋机、石蜡切片机、组织恒温烤片机和数码显微镜购自德国莱卡公司。

1.2 AS模型复制和实验分组

高脂饲料配方:基础饲料加入3.5%胆固醇、10%猪油、0.2%丙基硫氧嘧啶、0.5%胆酸钠及5%白糖。Wistar大鼠180只随机分为正常对照组(n=30)和AS模型组(n=150)。正常对照组大鼠每日饲以普通饲料;AS模型组大鼠实验开始时腹腔注射维生素D3(vitamin D3, VD3) 150 U·kg-1,连续3 d,每日饲以高脂饲料。实验周期为4周。AS模型复制成功后,AS组大鼠再随机分为AS组(30只)、Flu组(阳性药对照组,30只)和urantide(3、7和14 d)组(每组30只)。正常对照组和AS组大鼠每日尾静脉注射生理盐水30 μg·kg-1,连续14 d;Flu组大鼠每日灌胃给予Flu 5 μg·kg-1,连续14 d;urantide组大鼠每日尾静脉注射urantide 30 μg·kg-1,给药时间分别为3、7和14 d。

1.3 免疫组织化学法检测Col Ⅳ表达

采用S-ABC法对大鼠胸主动脉石蜡切片进行免疫组织化学染色,按操作说明进行。Introduction to Image-Proplus 6.0病理图像分析软件对每张切片(随机选取10个视野,×200)的免疫组织化学阳性信号进行图像分析,计算平均吸光度(A)值。以A值表示大鼠胸主动脉中Col Ⅳ的表达水平。

1.4 VSMC原代培养和实验分组

Wistar大鼠胸主动脉采用贴块法进行VSMC原代培养。按所加条件培养液分组:正常对照组,用含10%胎牛血清的DMEM培养液培养细胞;UⅡ组,正常组细胞加入UⅡ,终浓度为10-8 mol·L-1;Flu组,UⅡ组细胞加入Flu,终浓度为10-7 mmol·L-1;urantide组,UⅡ组细胞加入urantide,终浓度为10-10~10-6 mol·L-1

1.5 ELISA法检测HYP和Col Ⅳ水平

采用HYP试剂盒检测各组大鼠血清和尿液中HYP水平,于酶联免疫检测仪450 nm波长处测量A值;采用Col Ⅳ(ELISA)试剂盒检测VSMC培养上清中Col Ⅳ水平,于酶联免疫检测仪490 nm波长处测量A值。根据标准曲线求出直线回归方程,计算相应的HYP和Col Ⅳ水平。

1.6 统计学分析

采用SPSS 20.0软件进行统计学分析。各组大鼠血清和尿液中HYP水平、胸主动脉和VSMC培养上清液中Col Ⅳ表达水平均以x±s表示,多组间样本均数比较采用单因素方差分析,组间两两比较采用最小显著差法(LSD)。以P < 0.05为差异有统计学意义。

2 结果 2.1 正常对照组和AS模型组大鼠胸主动脉形态表现

HE染色结果显示:正常对照组大鼠胸主动脉血管内皮完整,中膜可见梭形平滑肌细胞,弹力纤维层结构清晰完整;AS模型组大鼠胸主动脉内膜明显增厚,血管内皮细胞排列不完整,平滑肌细胞增生,大量泡沫细胞堆积,出现典型AS病理改变。见图 1(插页五)。

A: Normal control group; B: AS model group. 图 1 2组大鼠胸主动脉形态表现(HE,×200) Fig. 1 Morphology of thoracic aorta of rats in two groups(HE, ×200)
2.2 各组大鼠胸主动脉中Col Ⅳ表达

各组大鼠胸主动脉内膜下不规则斑块内Col Ⅳ阳性表达水平比较差异有统计学意义(F=35.09, P < 0.01)。正常对照组大鼠胸主动脉中Col Ⅳ阳性颗粒呈微量表达;AS组大鼠胸主动脉内膜下不规则斑块内Col Ⅳ阳性颗粒与正常对照组比较明显增加(P < 0.01);urantide组Col Ⅳ阳性染色强度和范围与AS组比较均减少(P < 0.01),urantide给药14 d时作用最明显,优于Flu组。见图 2(插页五)和3

A: Normal control group; B: AS group; C: Flu group; D-F: Urantide group (3, 7, 14 d). 图 2 各组大鼠胸主动脉中Col Ⅳ表达(免疫组织化学,×200) Fig. 2 Expressions of Col Ⅳ in thoracic aorta of rats in various groups (Immunohistochemistry, ×200)
1:Normal control group; 2:AS group; 3:Flu group; 4-6:Urantide group(3, 7, and 14 d).*P < 0.05, **P < 0.01 compared with normal control group; P < 0.01 compared with AS group. 图 3 各组大鼠胸主动脉中Col Ⅳ表达 Fig. 3 Expressions of Col Ⅳ in thoracic aorta of rats in various groups
2.3 各组大鼠血清和尿液中HYP水平

HYP试剂盒检测结果显示:各组大鼠血清和尿液中HYP水平比较差异均有统计学意义(F=24.38, P < 0.01; F=26.72, P < 0.01)。与正常对照组比较,AS组大鼠血清中HYP水平明显升高(P < 0.01),而尿液中HYP水平则明显降低(P < 0.01)。与AS组比较,urantide组不同时间大鼠血清中HYP水平均明显降低(P < 0.01),给药7 d时降低作用最明显,接近于Flu组水平;与AS组比较,urantide组尿液中HYP水平明显升高(P < 0.01),给药14 d时增加作用最明显,优于Flu组水平。见表 1

表 1 ELISA法检测各组大鼠血清和尿液中HYP水平 Tab. 1 Levels of HYP in serum and urine of rats in various groups detected by ELISA method
[n=5, x±s, cB/(μmol·L-1)]
Group Serum Urine
Normal control 8.00±0.10 0.65±0.01
AS 82.86±0.25* 0.25±0.02*
Flu 17.07±0.22 4.35±0.03*△
Urantide
  3 d 68.42±0.51*△ 3.45±0.01*△
  7 d 21.12±0.19*△ 7.14±0.01*
  14 d 29.46±0.18*△ 8.96±0.02*△
   * P<0.01 compared with normal control group; P<0.01 compared with AS group.
2.4 各组大鼠VSMC培养上清中Col Ⅳ水平

各组VSMC培养上清中Col Ⅳ水平差异有统计学意义(F=31.04, P < 0.01)。与正常对照组比较,UⅡ组VSMC培养上清中Col Ⅳ水平明显升高(P < 0.01);与UⅡ组比较,10-9~10-6mol·L-1 urantide组VSMC培养上清中Col Ⅳ水平明显降低(P < 0.05或P < 0.01),其中10-6mol·L-1 urantide组抑制作用接近于阳性药Flu组水平。见图 4

1:Normal control group; 2:AS group; 3:Flu group; 4-8:10-10, 10-9, 10-8, 10-7, and 10-6 mol·L-1 urantide groups.*P < 0.05, **P < 0.01 compared with normal control group; P < 0.05, △△ P < 0.01 compared with AS group. 图 4 ELISA法检测各组大鼠VSMC培养上清中Col Ⅳ表达水平 Fig. 4 Levels of Col Ⅳ in VSMC culture supernatant of rats in various groups detected by ELISA method
3 讨论

AS是心血管系统中最常见的疾病,动脉壁胶原代谢紊乱是其发生发展的重要病因[10-11]。国内外研究[4-5]显示:Col Ⅳ是AS时胶原代谢紊乱的主要参与者。Col Ⅳ在AS各期的分布不同,在AS早期Col Ⅳ主要分布在泡沫细胞周围,AS晚期Col Ⅳ主要分布在动脉内膜下不规则斑块内和纤维帽下VSMC周围[12-13]。本研究免疫组织化学结果显示:AS组Col Ⅳ阳性颗粒主要表达在大鼠胸主动脉内膜下不规则斑块内,这一结果与有关Col Ⅳ在AS晚期分布的文献[13]报道一致。因此本文作者推测:腹腔注射VD3联合高脂饲料饲养法可损伤大鼠胸主动脉内膜,促进中膜的VSMC合成和Col Ⅳ大量分泌,当超过机体的代偿能力时,Col Ⅳ就在动脉壁沉积,促进AS的发生发展。如何有效地抑制AS大鼠Col Ⅳ的表达,对于治疗AS具有重要的临床意义。

UⅡ最早是从鱼的脊髓尾部下垂体中分离出的生长抑素样环肽,其与G蛋白偶联受体14(G protein-coupled receptor 14, GPR14)结合后发挥生物学效应。研究[14-15]显示:UⅡ能够促进VSMC增殖和胶原合成,促进巨噬细胞向泡沫细胞转化,与AS的发生发展有密切关系。urantide是UⅡ受体拮抗剂,可以通过阻断UⅡ与其受体GPR14的结合,起到治疗AS的作用,但具体作用机制尚未阐明[16-18]。Col Ⅳ是AS晚期时粥样斑块的主要成分,而urantide可抑制AS的发生发展。本实验通过尾静脉注射分3、7和14 d 3个组别,连续给予urantide 30 μg·kg-1,以观察urantide对AS大鼠Col Ⅳ表达的影响。本研究体内实验结果显示:urantide组Col Ⅳ阳性染色强度和范围与AS组比较均减少。由此表明:urantide对AS大鼠胸主动脉中膜的VSMC合成和分泌的Col Ⅳ有抑制作用。本研究采用ELISA法检测urantide对VSMC培养上清中Col Ⅳ水平的影响,结果显示:在VSMC的培养上清中,UⅡ对Col Ⅳ表达有上调作用,而urantide则对Col Ⅳ表达有下调趋势。动物水平和细胞水平的实验结果均证实urantide可抑制AS大鼠胸主动脉VSMC分泌和合成Col Ⅳ。

Col Ⅳ是由甘氨酸(glycine, Gly)、脯氨酸(proline, Pro)、HYP和羟赖氨酸等组成的胶原性氨基酸[19]。HYP是胶原纤维所特有,占胶原蛋白13.4%,测定动物血清或尿液中HYP水平,可反映机体胶原代谢情况[19-20]。本研究结果显示:与AS组比较,urantide组大鼠血清中HYP水平均明显降低,而尿液中HYP水平则明显升高。本文作者推测:urantide可促进动脉壁的Col Ⅳ降解加速,使血清中Col Ⅳ以HYP形式随尿液排出体外,使大鼠AS症状缓解。

综上所述,在AS发生发展过程中urantide可抑制AS大鼠胸主动脉中Col Ⅳ的分泌和合成,加速动脉壁内Col Ⅳ降解,改善AS病变程度,为临床应用urantide治疗AS提供了理论基础。

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