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Chinese Journal of Alzheimer's Disease and Related Disorders

Abbreviation (ISO4): Chinese Journal of Alzheimer's Disease and Related Disorders      Editor in chief: Jun WANG

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Relationship between NF-H expression and cognitive function in the serum of patients with asymptomatic carotid artery stenting

  • GUO Lei 1 ,
  • WANG Jianhong 2 ,
  • YANG Shu 2 ,
  • WANG Duozi 2 ,
  • YUAN Xiaofan 1 ,
  • GUO Fuqiang , 2
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  • 1 Department of Clinical Medical, Southwest Medical University, Luzhou 646000
  • 2 Department of Neurology, Sichuan Provincial People's Hospital, Chengdu 610000

Received date: 2020-06-28

  Revised date: 2020-07-05

  Online published: 2020-09-25

Abstract

Objective: To investigate the relationship between serum neurofilament protein heavy chain (NF-H) expression and cognitive function in patients with asymptomatic carotid artery stenosis before and after carotid artery stenting(CAS). Methods: From May 2018 to August 2019, 40 patients with asymptomatic carotid stenosis and mild cognitive impairment were admitted to the Department of Neurology of Sichuan Provincial People's Hospital as experimental group, and the control group was 40 health people. Blood samples in the operated patients were collected at three different points: 24 hours prior to CAS, 3 months after CAS in experimental group. Blood samples in control group were also collected. The serum concentrations of the NF-H were measured by ELISA. The cognitive function of the patients was evaluated by the mini-mental state examination(MMSE) and Montreal Cognitive Assessment(MoCA) before and 3 months after CAS.Compare the difference of serum NF-H expression level and the changes of cognitive function before and 3 months after operation. Results: Serum NF-H level of the patients in the experimental group was higher than that in the control group, with statistical difference (P< 0.01). The preoperative MMSE score in the experimental group was (26.08±1.59), which was lower than that in the control group (27.93±2.95), and the difference was statistically significant (P< 0.05). The preoperative MoCA score of the experimental group was significantly lower than that of the control group (24.48±1.89) vs (27.97±1.21), and the difference was statistically significant, (P< 0.01). Serum NF-H level decreased significantly (P< 0.01) in 3 months after operation compared with that before operation, and this is consistent with the improvement of cognitive function after 3 months--preoperative and postoperative comparison: MMSE(26.08±1.59) vs (27.48±1.95)(P< 0.05); MoCA(24.48±1.89) vs (26.83±.49)(P< 0.05). Pearson correlation analysis showed that the serum NF-H level was negatively correlated with MMSE score and MoCA score (P< 0.05). Conclusion: The patient with asymptomatic carotid artery stenosis have different degrees of brain injury and cognitive dysfunction. CAS can effectively improve the cognitive impairment associated with carotid stenosis, and the brain injury marker NF-H may be a biomarker for early recognition of cognitive impairment and may be used to monitor the cognitive function changes in patients after CAS.

Cite this article

GUO Lei , WANG Jianhong , YANG Shu , WANG Duozi , YUAN Xiaofan , GUO Fuqiang . Relationship between NF-H expression and cognitive function in the serum of patients with asymptomatic carotid artery stenting[J]. Chinese Journal of Alzheimer's Disease and Related Disorders, 2020 , 3(3) : 226 -231 . DOI: 10.3969/j.issn.2096-5516.2020.03.012

脑卒中是目前导致人类死亡的首位死因,缺血性脑卒中的发生率最高,具有高致残率,高复发率,高死亡率的特点[1]。其中,颈动脉狭窄是导致缺血性脑卒中发生的重要独立危险因素[2]。已有研究发现,无症状性颈动脉狭窄患者脑血流量(CBF)和脑血管反应性均明显降低,严重的血流动力学损害可致脑缺血性损伤、认知功能损伤[3-4]。对于无症状性颈动脉狭窄的患者,颈动脉支架置入术(CAS)作为颈动脉狭窄患者主要手术治疗方式目前已普遍用于临床,在脑卒中二级预防方面展现了其安全性和有效性[5]。然而,颈动脉支架置入术对无症状性颈动脉狭窄患者认知功能的作用尚不完全明确,且缺乏可靠的生物学评估指标。
许多研究表明神经丝蛋白重链(NF-H)作为大脑的特异性蛋白,是轴突损伤变性和神经元丢失的标志[6]。已有研究观察到,在一些疾病中患者血清NF-H的表达增加,包括卒中、多发性硬化、脑外伤等[7-9]。但是NF-H在颈动脉狭窄的患者血清中的表达及其与认知功能的关系尚未见报道。因此本研究旨在探讨颈动脉支架术患者术前、术后3个月血清NF-H表达水平差异及其与术前及术后3个月认知功能变化情况的关系。

1 资料与方法

1.1 一般资料

本研究通过了四川省人民医院伦理委员会的批准。入选2018年5月至2019年8月于四川省人民医院神经内科病房住院的患者80例。实验组为接受CAS治疗的40例伴有轻度认知功能损害的无症状颈动脉狭窄患者,对照组为40例健康人群。

1.2 纳入标准:

1)年龄≥18周岁;
2)根据NASCET(North American Symptomatic Carotid Endarterectomy Trial)标准确诊为无症状性颈动脉狭窄且符合CAS治疗指南[5]:无症状性颈动脉狭窄> 70%;
3)根据《中国痴呆与认知障碍诊治指南:轻度认知障碍的诊断和治疗》标准诊断为轻度认知障碍[10]:主诉认知功能障碍且有客观证据,或经客观证据证实存在认知功能下降,但日常生活能力基本具备;
4)术后监测患者的一般情况和神经状态,所有患者的一般情况良好且复查头部CT均无新发脑梗死;
5)患者及患者亲属理解并签署知情同意书。

1.3 排除标准:

1)可能导致认知功能损害的神经系统疾病比如痴呆,帕金森病,多系统萎缩,脑炎;
2)其他导致认知功能下降的系统疾病比如自身免疫性疾病;肿瘤;类风湿关节炎;严重心、肝、肾损害疾病等;
3)造影剂过敏;
4)患者或患者亲属拒绝签署知情同意书者。

1.4 标本采集

该研究对正常对照组采集血液标本;颈动脉狭窄患者分两次时间点采集血液标本:术前、术后3个月。所有研究对象均于清晨采集肘静脉血4 ml,离心取上层血清,分装于 EP 管中立即保存在-80 ℃低温冰箱中保存备检,待所有标本均收集完毕后统一采用酶联免疫吸附试验(ELISA)法测定各组血清NF-H水平。观察颈动脉狭窄患者术前及术后3个月血浆中的NF-H表达变化。

1.5 检测方法

本实验将样本和标准物分别加入含有NF-H抗体的试剂(NF-H ELISA试剂盒:Human NF-H ELISA KIT,货号:ZC-54478,规格:96孔/盒、48孔/盒,茁彩生产)的96孔微孔板中,制成固相载体,其中NF-H连接于固相载体上的抗体结合,然后彻底洗涤后加入NF-H抗体,将未结合的生物素抗体洗净后,加入HRP标记的亲和素,再次彻底洗涤后加入TMB底物显色。TMB在过氧化物酶的催化下转化成蓝色,并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的NF-H呈正相关。用酶标仪(型号,SpectraMAX Plus384,美谷分子仪器有限公司生产)在450nm波长下测定吸光度(OD值),计算样品浓度。以上操作均严格按照有关操作说明书进行。

1.6 认知功能评估

对照组认知功能评估由神经内科医师对其进行MMSE量表及MoCA量表评估。实验组对象认知功能评估由神经内科医师在术前1周内及术后3个月行MMSE量表及MoCA量表评估。

1.7 统计方法

采用Graphpad Prism 6.0软件处理数据。计量资料以平均数±标准差表示,组间比较采用t检验,计数资料比较采用χ2检验,相关性分析使用Pearson检验,P< 0.05为差异有统计学意义。

2 结果

2.1 各组基线资料比较

所选患者在年龄、性别、高血压、糖尿病、高脂血症、总胆固醇、甘油三酯、空腹血糖、低密度脂蛋白、同型半胱氨酸各组间比较差异无统计学意义(P> 0.05),见表1
表1 实验组和对照组一般资料比较(x±s)
组别 对照组 实验组 P
n(男) 40(24) 40(21) 0.812
年龄 58.00±13.70 66.95±9.03 0.391
高血压 14 12 0.145
糖尿病 9 12 0.577
高脂血症 20 13 0.545
TG(μmol/L) 1.80±0.80 1.50±0.68 0.100
TC(μmol/L) 4.58±4.81 3.52±1.40 0.496
LDL-C(mmol/L) 2.03±0.77 1.89±0.78 0.625
Hcy(μmol/L) 15.27±8.77 14.53±5.45 0.096
HbA1c(%) 5.74±1.51 6.71±2.70 0.124

以上数据用平均数±标准差或n表示;TG:甘油三酯;TC:总胆固醇;LDL-C:低密度脂蛋白;Hcy:同型半胱氨酸;HbA1c:糖化血红蛋白。

2.2

Pearson相关性分析得出,劲动脉狭窄患者术前血清NF-H水平与患者MMSE评分呈负相关(P< 0.01),见表2
表2 实验组术前NF-H与MMSE评分及MoCA评分的相关性分析
R P
术前NF-H(ng/ml) MMES(分) -0.501 0.001
术前NF-H(ng/ml) MoCA (分) -0.700 0.000

2.3

实验组术前血清NF-H浓度明显高于对照组(图1),MMSE评分及MoCA明显低于对照组(图2),均具有统计学差异,见表3
图1 对照组与实验组术前患者血清NF-H浓度的比较,对照组NF-H水平明显低于实验组术前水平(P

****< 0.001); Control:对照组;Before:实验组术前

图2 对照组与实验组术前患者MMSE评分及MoCA评分的比较,Control:对照组;Before:实验组术前。A:对照组MMSE评分高于实验组术前水平(P**< 0.01); B:对照组MoCA评分高于实验组术前水平(P**< 0.01)
表3 实验组术前与对照组NF-H浓度,MMSE、MoCA评分比较
Control Before P
NF-H(ng/ml) 2.34±1.09 5.08±2.71 0.000 1
MMES(分) 27.93±2.95 26.08±1.59 0.002 0
MoCA(分) 27.97±1.21 24.48±1.89 0.006 1

表3以上数据用平均数±标准差,Control:对照组;Before:实验组术前。

2.4

颈动脉支架术前较术后3个月患者血清NF-H水平显著下降(P< 0.01,图3),同时患者3月后MMSE评分及MoCA较术前增加(P< 0.01,图4),见表4
图3 实验组术前与术后3个月患者血清NF-H浓度的比较,术后3个月患者血清NF-H水平明显低于实验组术前水平(P< 0.05); Before:实验组术前,3 month:实验组术后3个月
图4 实验组术前与术后3个月患者MMSE评分及MoCA评分的比较。Before:实验组术前,3 month:实验组术后3个月。A:术后3个月患者MMSE评分明显高于实验组术前水平(P**< 0.01); B:术后3个月患者MoCA评分明显高于实验组术前水平(P**< 0.01)
表4 实验组术后3个月与对照组NF-H浓度,MMSE、MoCA评分比较
Before 3 month P
NF-H(ng/ml) 5.08±2.71 1.65±1.13 0.002
MMES(分) 26.08±1.59 27.48±1.95 0.008
MoCA(分) 24.48±1.89 26.3±1.49 0.009

表4以上数据用平均数±标准差,Control:对照组;3 month:实验组术后3月。

3 讨论

轻度认知功能障碍是一种介于正常衰老和痴呆的中间状态,主要是记忆力或其他进行性认知功能减退,认知功能是人类健康和生活质量的主要决定因素[11]。颈动脉狭窄超过50%就可引起大脑低灌注所致认知功能损伤,但不一定都出现脑血管事件,这部分无症状患者的认知功能损害很难被识别[12],因此早期筛查和干预认知功能障碍显得尤为重要。颈动脉狭窄常发生在约10%的65岁以上的成年人中,每年约有21%的颈动脉狭窄患者发生脑血管事件,40%~50%的患有颈动脉狭窄的老年人有认知功能障碍,严重影响患者预后[13-16]。然而,目前尚缺乏颈动脉狭窄相关认知功能损害的血清学生物学标志物,而基于血液学开发的生物学标志物具有成本低、操作简便、快速、灵敏等特点[17]。因此,本研究着重探讨CAS对无症状性颈动脉狭窄患者认知功能的影响及其可能存在的生物学标志物。
轻度认知功能损害的复杂性和异质性造成了其诊断的困难性,目前临床上对于患者认知功能评估主要采用MMSE量表、MoCA量表、Addenbrook改良认知评估量表(Addenbrooke's Cognitive Examination- Revised, ACE-R)三种量表,此外国外还采用其他综合量表评估认知功能,比如洛文斯顿认知功能评定量表(Loewenstein Occupational Therapy Cognitive Assessment, LOTCA)、神经行为认知状况测试(Neurobehavioral Cognitive Status Examination, NCSE)等,它们主要从时间定向力,地点定向力,即刻记忆,注意力及计算力,延迟记忆,语言,视空间等多个方面评估患者的认知功能[18]。ACE-R对轻度认知功能损害的灵敏度和特异度均较高,和MoCA量表相似,但其受年龄影响较大且过于耗时,单独使用MMSE量表灵敏度较低,在区分轻度认知功能障碍和健康人群上有一定的局限性,需要联合其他检查以提高敏感度,而MoCA增加了执行能力评价,突出记忆领域的测试[19],因此本研究采用MMSE量表及MoCA量表两种量表联合评估患者认知功能。
NH-F是神经元中最丰富的中间神经丝之一,在轴突损伤过程中被释放,是轴突损伤、变性和神经元丢失的标志物,本研究中发现颈动脉狭窄患者血清NF-H表达的升高,其机制可能是由于颈动脉狭窄患者脑血流量和脑血管反应性均明显降低,脑缺血事件的发生与严重的血流动力学损害所致脑损伤,由于缺乏葡萄糖和氧气而导致的神经元死亡,导致轴突蛋白NF-H的释放所致[20-21],这一结果与Sellner J等人的研究保持一致[22]。此外,目前尚无研究发现血清NF-H与阿尔兹海默症等神经退行性疾病所致认知功能损害相关,由此可以推断,本研究中发现颈动脉狭窄患者术前MMSE及MoCA评分减低所反应的认知功能损伤提示,这种认知功能损害是由于颈动脉狭窄后缺血性损害所致神经元坏死、轴突及胶质细胞丢失、皮质和皮质下灰质失联后继发变性所致,而并非神经退行性疾病所致[11]。因此,本研究结果表明,无症状性颈动脉狭窄患者MMSE及MoCA评分低于健康人群,而血清脑损伤标志物NF-H表达水平较健康人群增高,这提示无症状性颈动脉狭窄患者存在不同程度的认知功能障碍,脑损伤标志物NF-H可能是早期识别无症状性颈动脉狭窄患者轻度认知功能损害的生物学标志物。本研究中Pearson相关性分析提示,随着患者血清NF-H的表达增加,MMSE评分及MoCA评分呈下降趋势,进一步证明了上述结论。
另外,本研究还发现,CAS术后3个月患者血清NF-H水平下降,MMSE及MoCA评分升高,患者认知功能得到改善。既往已有研究发现颈动脉狭窄患者出现认知功能损害的原因是由于大脑低灌注所致[17],本研究中出现CAS术后认知功能可得到改善这一结果的机制可能是由于颈动脉支架术后患者大脑灌注增加,可有效缓解大脑低灌注所致神经元损伤,皮质和皮质下灰质的失联状态得到恢复,从而阻止了脑缺血事件的发生及认知功能的进一步损害,这提示颈动脉支架可有效改善颈动脉狭窄相关的认知功能损害,而结合本研究血清NF-H在颈动脉狭窄患者术后的表达下降,这提示血清NF-H或能成为辅助临床医生监测CAS术后患者认知功能改变的生物学标志物,有利于临床医生对颈动脉狭窄合并有认知功能损害的患者进行早期识别及个体化治疗,改善颈动脉狭窄患者的预后。
由于客观条件限制,本研究也存在不足之处:单中心研究,样本量小,血清NF-H用于评估认知功能的灵敏性和特异性仍需进一步被阐明和优化。

4 结论

无症状颈动脉狭窄患者存在不同程度的脑损伤及认知功能障碍,可引起血清NF-H表达增加;颈动脉支架置入术可有效改善患者认知功能,血清NF-H水平下降提示脑损伤标志物NF-H有望成为早期识别认知功能损害及监测颈动脉支架患者术后认知功能改变的生物学标志物。
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