Ischemia Modified Albumin and miR-126 Play Important Role in Diagnosis of Posterior Circulation Transient Ischemic Attack and Prediction of Secondary Cerebral Infarction
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.310100
Source of Support: None, Conflict of Interest: None
Keywords: Ischemic modified albumin; miR-126; posterior circulation transient ischemic attack; secondary cerebral infarction
The objective to evaluate the emergency intervention of “cerebral stroke warning” for transient ischemic attack (TIA) is of great significance in the treatment and prognosis of severe TIA patients. The posterior circulation TIA patients accounting for 1/4th of all the TIA patients have typical symptoms of dizziness and falling. Moreover, the ratio of the development to stroke is not less than that of the internal carotid arterial system.
Clinical features such as ABCD2 score, Essen Stroke Risk Rating Scale,, and imaging examination containing digital subtraction angiography, magnetic resonance imaging, and diffusion-weighted imaging have been systematically explored to predict the risk of secondary cerebral infarction caused by TIA. Maas and Furie reported that ischemia modified albumin (IMA) may become a molecular marker of the early diagnosis and prognosis of ischemic cerebral infarction. Our previous studies showed that IMA had a good effect on the diagnosis of anterior circulation TIA and prediction of cerebral infarction. MicroRNA is noncoding nucleotide consisting of 21–23 nucleotide bases, which broadly participate in transcriptional regulation of encoding protein nucleotide and play an important role in the development of organisms, disease occurrence, and development. Recent research proved that the abnormal expression of microRNA occurred after ischemic cerebral stroke. Another report demonstrated that the role of miR-126 was important in the progression of ischemic infarction. However, there were no related reports on how the IMA and miR-126 levels change after posterior circulation TIA and their roles in diagnosis and prediction. Thus, the changes of IMA and miR-126 levels and their correlation with secondary cerebral infarction after posterior circulation TIA were explored in this research so as to investigate the value of IMA and miR-126 in diagnosing and predicting secondary cerebral infarction.
A total of 106 patients from January 2011 to June 2014 within 3 h after posterior circulation TIA in the Department of Neurology were included in this research, there were 70 male patients and 36 female patients aged 39–85 years with a mean average of 69.74 ± 9.81 years. The inclusion criterion was according with the TIA diagnostic criteria proposed by American Heart Association/American Stroke Association. Meanwhile, 80 healthy volunteers in the same period in our hospital were included in the control group. There were 48 males and 32 females aged 40–76 years, and the mean age was 56.2 ± 10.9 years. Exclusion criteria: (1) Unilateral limb weakness as the main symptom and difficulty in distinguishing from disease of arteria carotis internal system; (2) severe liver and kidney dysfunction, cancer, and chronic inflammatory diseases; (3) a history of surgery or trauma before a month of disease onset; (4) a history of coronary artery disease, valvular heart disease, stroke, pulmonary embolism, and thromboembolic circulation-related diseases; (5) 24 h load motion abnormalities; (6) serum albumin <35 g/L or >55 g/L; and (7) pregnancy. Ethics Committee of Taizhou Second People's Hospital of Jiangsu Province approved the research, and all the patients signed an informed consent.
ABCD2 rating method and collection of baseline material
Methods of the scoring had been reported previously. Briefly, all the patients implemented ABCD2 rating at admission and were divided into low-risk group (≤3 score); medium-risk group (4–5 score); and high-risk group (≥6 score).
The related data were collected at admission, and the laboratory tests including blood glucose, lipids, and liver and kidney functions were implemented the next day.
Ischemia modified albumin examination
The method had been reported previously. Briefly, the venous blood was drawn for 4 ml at 3 h, 6 h, and 12 h after TIA onset. And the serum was separated with 3000 r/min for 10 min at −80°C, and was tested by Siemens Work Cell assembly line (Siemens, Germany). Two endpoints method was applied to test IMA. Agent was purchased from Beijing Huayu Yikang Corporation (batch number: 140913).
Detection of miR-126
Real-time polymerase chain reaction (RT-PCR) was used to test miR-126 in serum and miRNA was extracted, the reaction system involved in RT buffer for 2 ul, primer (2 umol/l) for 0.5 ul, RNA for 6.25 ul, dNTP for 0.5 ul, M-MLV for 0.5 ul, RNase inhibitor for 0.5 ul, and RNase–Free ddH2 O was complemented to 20 ul. The reverse transcription was carried out at 16°C for 15 min, 35°C for 60 min, and 80°C for 15 min. Primer sequence of hsa-miRNA-126 was L 5′-GCCCTCGTACCGTAAT-3′ R 5′-GTGCAGGGTCCGAG-GT-3′. The total volume of miRNA PCR of fluorescent quantitation PCR reaction was 20 ul, including, 2 × Super Real PreMix for 10 ul, downstream primer for 0.3 umol/L, and cDNA template for 2.5 ul. β-actin sequence was 5-TGCGTGACATTAAGGA
GAAG-3,5,-GCTCGTAGCTCTTCTCC AG-3,. PCR reaction system program detected by MiRNA was set at 95°C for 2 min, 95°C for 20 s, 60°C for 20 s, and 72°C for 1 min with 42 cycles. And German Qiagen RT-PCR System Detection was used in the research.
Diagnosis and follow-up
All the patients were given corresponding therapy at admission according to disease condition and registered in the follow-up booklet. The follow-up lasted for 30 days until first recorded TIA, and the conditions of secondary cerebral infarction diagnosed by a physician in the neurological department with radiographic evidence were observed in 0–30 d after posterior circulation TIA.
The statistical analysis was performed by SPSS 19.0 statistical software (version 19.0; SPSS Inc., Chicago, IL, USA). Quantitative data were expressed as mean ± standard deviation, qualitative data were expressed by ratio or percentage, and the study focused on confirmed cerebral infarction after posterior circulation TIA. The linear correlation between the two sets of variables was analyzed by the Pearson-Correlation method. IMA, miR-126 threshold value, and diagnostic sensitivity and specificity were calculated by receiver operating characteristic (ROC) curve. Cox survival model was established by the back exclusion comparative method, and screened risk factors were correlated with secondary cerebral infarction. The predictive value of risk factors leading to secondary cerebral infarction was calculated by logistic regression equations and regression testing and the Chi-squared value was compared. P < 0.05 was considered to indicate statistically significant.
Among 106 patients, there were 53 patients (50.00%) with hypertension, 23 patients (21.70%) with diabetes and abnormal glucose tolerance, and 31 patients (29.25%) with dyslipidemia, 34 smoking patients (32.08%), 36 alcoholic patients (33.96%), and the ABCD2 score was 3.47 ± 1.61 [Table 1].
Follow-up of secondary cerebral infarction after posterior circulation transient ischemic attack
Secondary cerebral infarction occurred in 11 patients (10.38%) within 7 days and 17 patients (16.38%) within 8–30 days among 106 patients after posterior circulation TIA.
Diagnostic value of serum ischemia modified albumin level for the posterior circulation transient ischemic attack
Ischemia modified albumin level showed a remarkable increase after posterior circulation TIA and the IMA level reached 87.90 ± 24.98 u/L at 3 h, 59.18 ± 11.89 u/L at 6 h, and 56.99 ± 12.82 u/L at 12 h. The level of serum IMA at 3 h and 6 h after posterior circulation TIA were significantly higher than 54.19 ± 10.10 u/L in the healthy control group (P = 0.000, 0.003). ROC was applied to analyze IMA levels at 3 h, 6 h, and 12 h, and the area under the ROC curve on each time point were 0.923, 0.620, and 0.576, and the corresponding 95% confidence interval were 0.885–0.961, 0.540–0.700, and 0.495–0.658, respectively, so it revealed that the level of IMA at 3 h was of great diagnostic value. When IMA = 67.80u/L was ideal cutpoint, the sensitivity and specificity were 80.20% and 96.20%, respectively [Figure 1].
Diagnosis value of serum miR-126 level on posterior circulation transient ischemic attack
The RT-PCR values of miR-126 were 9.14 ± 1.04 at 3 h, 8.63 ± 1.62 at 6 h, and 5.79 ± 2.39 at 12 h after posterior circulation TIA onset. And the value was greatly declined at 6 h and 12 h than that 9.35 ± 1.76 in the healthy control group (P = 0.003, 0.000). ROC test showed that the area under the ROC curve at 12 h was 0.851 and 95% confidence interval was 0.794–0.908. When miR-126 = 8.05 was ideal cutpoint, the sensitivity and specificity were 87.50% and 79.20%, respectively [Figure 2].
Correlation between ischemia modified albumin level and miR-126
There was no significant difference between IMA level and miR-126 in healthy volunteers (r = −0.061, P = 0.590). ROC detection revealed that IMA level at 3 h and miR-126 at 12 h after posterior circulation TIA were valuable in diagnosing posterior circulation TIA. Moreover, the study further explored the correlation between IMA level at 3 h and miR-126 at 12 h [Figure 3].
Relation between clinical data and secondary cerebral infarction after posterior circulation transient ischemic attack
Baseline variables were defined before the establishment of Cox risk prediction model. Younger than 60 years old were included in “Category 1” and 60–69 years old were in “Category 2,” and over 70-year-old were in “Category 3.” ABCD2 scores of 0–3 were classified as “Category 1” and over 4 points were in “Category 2.” Besides, “Category 0” included patients without related history and “Category 1” included patients with related history. Meanwhile, IMA and miR-126 were defined according to ROC detection results, IMA ≤67.80 u/ml was defined as normal (Category 0), IMA >67.80 u/ml was defined as abnormality (Category 1), and miR-126 <8.05 was defined was abnormality, otherwise it was normal. Each categorical variable was substituted into Cox model [Table 2]. Logistic regression equations were established on the basis of Cox results and risk factors (hypertension, diabetes, and dyslipidemia), risk factors combined with ABCD2 score, risk factors combined with IMA level, and risk factors plus relative expression amount of miR-126 were substituted into logistic regression equations to compare the Chi-squared values [Figure 4].
Since the concept of TIA was proposed in the 1950s or 1960s, its definition was always reformulating and developing, but the transient neurological deficit of central nervous system, a typical cerebral stroke, can lead to secondary cerebral infarction in a short time in TIA patients. Research reported that the overall risk of stroke following TIA was 2.1% at 2 days and 5.2% at 7 days. Thus, recently, people have attached great importance to the accurate evaluation of disease conditions of patients in the perspective of clinical manifestation and imaging analysis to evaluate the prognosis of TIA. Presently, ABCD2 score is most widely applied and a perfect model in predictive models available. However, a recent study revealed that, compared with anterior circulation TIA, ABCD2 score was unfavorable in predicting secondary cerebral infarction after posterior circulation TIA.
Terminal amino acid is a peculiar sequence in human serum albumin, and it is the binding sites of some transitional metallic ions such as Co, Cu, and Ni2+. Compared with other animal serum albumin, the human serum albumin is easily destroyed by the degradation and destruction of biochemical factors. This degraded and decorated HAS is IMA, and the acute ischemia can increase rapidly in minutes. In the early period of ischemia, this IMA can be detected in the serum before myocardial necrosis, and it may contribute to the differential diagnosis of the acute coronary syndrome. In 2003, IMA became the first early biochemical marker of myocardial ischemia approved by FDA in America. The study of application of IMA in acute cerebrovascular diseases proved that the early level of serum IMA in ischemic cerebrovascular patients was remarkably higher than that in the control group.
The chain reaction, including, energy metabolism disturbance, excessive influx of calcium ions released by excitatory neurotransmitter, radical reaction and brain cell death, was the important factor of TIA impairment, which eventually caused increased IMA relating to ischemia and reperfusion injury. The more severe the increased degree was, the greater the possibility of re-infarction was. It was reported that IMA level and ischemic stroke were significantly correlated, and the concentration of IMA in the diagnosis of ischemic disease, especially cardiovascular disease, was of great significance. In this study, ROC curve analysis showed the best diagnostic value of IMA was 67.78 u/ml and the sensitivity and specificity of diagnosing posterior circulation TIA were 80.20% and 96.20%, respectively, which indicated sensitivity and specificity were high.
Normal vascular structure and function play an important role in prevention and treatment of vascular diseases such as ischemic heart disease and ischemic stroke. Ischemic injury mediated epigenetic regulation of endothelial cells plays an important role in vascular structure and function repairment So far, researches have showed that the disturbance expression of microRNA manifested in a variety of clinical diseases. Abnormal expression of microRNA, the diagnosing marker existing in plasma, and brain tissue in stroke patients and animal models, are of great value in the diagnosis and prognosis of cerebral infarction. The study of Long et al. showed miR-126 expression was significantly decreased in patients with cerebral infarction, which can be used as a biological diagnostic marker of acute cerebral infarction. Moreover, miR-126 promoted angiogenesis and inhibited ischemic brain tissue inflammation damage. Our research revealed that when the best diagnostic value of miR-126 was 8.05 and the sensitivity and specificity of diagnosing posterior circulation TIA were 87.50% and 79.20%, respectively, which indicated miR-126 detection had high sensitivity and specificity in diagnosing posterior circulation TIA.
Our research proved that the mean IMA level at 3 h after posterior circulation TIA was significantly higher than the normal level and decreased to normal level at 6 h and 12 h, which was almost equaled to IMA level after anterior circulation TIA. The miR-126 level at 3 h was almost equaled that in the healthy control group, but it decreased at 6 h and 12 h, especially at 12 h. And the levels of IMA at 3 h and miR-126 at 12 h were negatively correlated. Meanwhile, it also suggested that hypertension, diabetes and impaired glucose tolerance, and dyslipidemia were independent risk factors of secondary cerebral infarction after posterior circulation TIA. Chi-squared results showed that IMA level was abnormally increased at 3 h and miR-126 level was significantly reduced at 12 h, medium risk factors, risk factors, and ABCD2 score were more valuable in diagnosing secondary cerebral infarction in clinic after posterior circulation TIA (P < 0.05).
Our research revealed that IMA level was rapidly increased in a short time after posterior circulation TIA and abnormal expression of miR-126 occurred. However, a series of clinical research showed that the specialty, sensitivity, and IMA values of positive and negative prediction were irregular under the circumstances of diversified cut-off value,,,, and IMA level raised in different degrees when the myocardial ischemia, end-stage renal disease, early pregnancy and ischemia of gastrointestinal tract, and skeletal muscle occurred. Only abnormal expression of miR-126 of posterior circulation TIA were studied in this research, and expression of TIA was excluded, so the study involved fewer samples with short-term tracking. Hence, further researches were needed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]