Arq Bras Cardiol abc Arquivos Brasileiros de Cardiologia Arq. Bras. Cardiol. 0066-782X 1678-4170 Sociedade Brasileira de Cardiologia - SBC wwzjXKMYSbb9Yqd4LMMNQ7F S0066-782X2017000800156 10.5935/abc.20170102 S0066-782X2017005001305 Review Article A Meta-Analysis of Circulating Microvesicles in Patients with Myocardial Infarction Wang Zhida 1 # Cai Wang 2 # Hu Shaolan 1 Xia Yufei 3 Wang Yao 4 Zhang Qi 5 * * Chen Liming 1 * * Tianjin Medical University Tianjin China Key Laboratory of Hormones and Development (Ministry of Health) - Tianjin Key Laboratory of Metabolic Diseases - Tianjin Metabolic Diseases Hospital & Tianjin Institute of Endocrinology - Tianjin Medical University, Tianjin - China Tianjin Medical University Tianjin Medical University Tianjin Nankai Hospital Department of Surgery Tianjin China Department of Surgery - Tianjin Nankai Hospital - Tianjin Medical University, Tianjin, China Tianjin Medical University Tianjin Medical University School of Nursing Tianjin China School of Nursing - Tianjin Medical University, Tianjin - China Tianjin Medical University Tianjin Medical University School of Basic Medical Science Department of Pharmacology Tianjin China Department of Pharmacology - School of Basic Medical Science - Tianjin Medical University, Tianjin - China Tianjin Medical University Nankai Hospital Institute of Integrative Medicines for Acute Abdominal Diseases Tianjin China Institute of Integrative Medicines for Acute Abdominal Diseases - Nankai Hospital, Tianjin - China Mailing Address: Qi Zhang; Liming Chen, Institute of Integrative Medicines for Acute Abdominal Diseases-Nankai Hospital, Tianjin-China (Qi Zhang); Hormones and Development (Ministry of Health)-Tianjin Key Laboratory of Metabolic Diseases-Tianjin Metabolic Diseases Hospital & Tianjin Institute of Endocrinology - Tianjin Medical University,Tianjin-China (Liming Chen). E-mail: zhangqi8501@126.com; xfx22081@vip.163.com

Zhida Wang and Wang Cai contributed equally and are the first authors;

Qi Zhang and Liming Chen contributed equally and are the corresponding authors

Author contributions

Conception and design of the research and Writing of the manuscript: Wang Z, Cai W; Acquisition of data: Hu S; Analysis and interpretation of the data: Xia Y; Statistical analysis: Wang Y; Obtaining funding and Critical revision of the manuscript for intellectual content: Zhang Q, Chen L.

Potential Conflict of Interest

No potential conflict of interest relevant to this article was reported.

 10 07 2017 Jul-Aug 2017 109 2 156 164 20 01 2017 15 03 2017 This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background:

Cell-derived microvesicles (MVs) are vesicles released from activated or apoptotic cells. However, the levels of MVs in myocardial infarction have been found inconsistent in researches.

 Objective:

To assess the association between MVs and myocardial infarction by conducting a meta-analysis.

 Methods:

A systematic literature search on PubMed, Embase, Cochran, Google Scholar electronic database was conducted. Comparison of the MVs levels between myocardial infarction patients and healthy persons were included in our study. Standard Mean Difference (SMD) and 95% confidence interval (CI) in groups were calculated and meta-analyzed.

 Results:

11 studies with a total of 436 participants were included. Compared with the health persons, AMVs [SMD = 3.65, 95% CI (1.03, 6.27)], PMVs [SMD = 2.88, 95% CI (1.82, 3.93),] and EMVs [SMD = 2.73, 95% CI (1.13, 4.34)], levels were higher in patients with myocardial infarction. However, LMVs levels [SMD = 0.73, 95% CI (-0.57, 2.03)] were not changed significantly in patients with myocardial infarction.

 Conclusions:

AMVs, PMVs and EMVs might be potential biomarkers for myocardial infarction.

 Keywords: Myocardiaol Infarction Biomarkers Cell-Derived Microparticles Annexion A5 Blood Platelets Leukocytes Endothelium National Natural Science Foundation of China 81602496 Science and Technology Foundation of Administration of Traditional Chinese Medicine of Tianjin, China 2015022 13047 Science and Technology Foundation of Tianjin Municipal Commission of Health and Family planning 2013KZ054 This study was funded by National Natural Science Foundation of China through grant n°. 81602496; Science and Technology Foundation of Administration of Traditional Chinese Medicine of Tianjin, China, nos 2015022 and 13047; Science and Technology Foundation of Tianjin Municipal Commission of Health and Family planning, n°. 2013KZ054. Introduction

Ischemic Heart Disease (IHD) is one of the cardiovascular diseases, which impairs human health.1 Atherothrombosis, endothelial dysfunction and cell apoptosis are on the pathologic basis in these diseases. The relevant studies in this area have suggested that cell-derived microvesicles (MVs) are related with platelet activation, endothelial damage and inflammation associated with the existence of cardiovascular risk factors.2-4 Since they are involved in the pathophysiologic process of diseases, attention has being focused on the relationship between MVs and myocardial infarction (MI).5-8 Increasing evidences imply that MVs might be considered as novel biomarkers or mediators helpful in understanding the mechanisms of cardiovascular diseases.

MVs are used to describe a population of sub-cellular vesicles released from plasma membrane during cell activation or apoptosis and identified by size range from 100 nm to 1.0 µm in diameter. MVs constitute a heterogeneous population, different in cellular origin, numbers, size, antigenic composition, and functional properties. Alterations in the amounts of different cell-derived MVs may provide information on the pathophysiologic changes. Although many studies have shown that myocardial infarction is associated with MVs, the information obtained shows heterogeneous result, with a high variation regarding MVs size, MVs type, MVs levels, inclusion criteria and methods. Thus, we performed a meta-analysis of the changes of Annexin V positive MVs (AMVs), platelet MVs (PMVs), endothelial MVs (EMVs) and leukocytes MVs (LMVs) in patients with myocardial infarction and healthy persons.

 Methods Data Sources and Searches

We searched the databases of MEDLINE (pubmed), Embase, Cochrane and Google Scholar electronic database for articles from 2000 to 2013. All searches were applied with the following medical subject headings: “myocardial infarction”, “primary percutaneous coronary intervention”, “stenting”, “balloon angioplasty”, “acute coronary syndrome” or “coronary ischemia”, “microparticles”, “cell-derived microparticles”, “circulating microparticles”, “microvesicles”. These searches were restricted to publications limited to research on humans. A manual search for references cited in the published studies and relevant review articles was also performed to identify additionally suitable investigations for our purpose. For unpublished and published studies that were not exhaustively disclosed, the attempt through e-mail was made to contact principal investigators in order to retrieve missing data. Finally, well-known experts in this area were contacted to ensure that all relevant data were captured.

 Study Selection

Two of us performed the identification of relevant abstracts and the selection of studies based on the criteria described below independently, and a third investigator resolved any discrepancy. We selected studies comparing the levels of diverse MVs: total, platelet-, endothelial-, leukocyte-derived between healthy persons and patients with myocardial infarction.

Studies were included if they met the following criteria: (i) Study entitled circulating MVs correlated with MI; (ii) Design of study was case-control study or cohort study; (iii) The MI as a research subgroup independently extract relevant information MI. We excluded the following: (i) Review; (ii) Not full text, only a summary; (iii) Animal testing.

 Data Extraction and Synthesis

We extracted information including study and population characteristics, sample size, study design, and outcomes relevant to this study. Means and standard deviations of MVs levels were extracted. When an article complied with the inclusion criteria but lacked information on parameters for analysis, or when outcomes were reported but not related to myocardial infarction, we contacted the authors to obtain raw data. The quality of studies was assessed using the Downs and Black checklist.

 Statistical Analysis

The data was analyzed using RevMan 5.0 statistical software provided by the Cochrane Collaboration analyzed. SMD and 95% CI were used as summary estimates. The presence of heterogeneity between studies was tested with the χ² test for heterogeneity and the I² statistic. Heterogeneity was significant when p< 0.05 or I² was more than 50%. A random-effects model was used in all analyses to test the stability of the results to the choice of the statistical model. If significant heterogeneity, results of the random-effects model are used. We defined a priori sensitivity analysis of high-quality studies for each clinical outcome. The potential for publication bias was evaluated using the funnel plot approach.

 Results Search Results

172 articles identified from MEDLINE (pubmed), Embase, Cochrane and Google Scholar electronic database were analyzed; and then, 140 were excluded based on title and abstract. After detailed evaluation of potential eligibility, 11 studies met all the inclusion criteria and were retrieved for meta-analysis.9-19 The trial flowchart is summarized in Figure 1.

Flow diagram of search strategy and study selection.

Baseline Characteristics of the studies

The characteristics of all included studies are presented in Table 1. These studies were published from 2004 to 2013. Sample size ranged from 5 to 61. A total of 436 participants (186 healthy controls and 250 MI patients) were included. Among these studies, the results of MVs were expressed differently. Six reports were expressed as numbers of MVs in plasma per microliter, milliliter and liter. Three reports were expressed as PS eq (phosphatidylserine equivalents), one report was expressed as numbers of MVs in platelet count, and one report was expressed as plasma concentrations of MVs. There were four reports only report the median, range and the size of the trial. In order to estimate the mean and the variance in these articles, we used the number of sample and elementary inequalities.20

Characteristic of included studies
Author/Year Study object Measurement method of MVs Units of MVs Sample size
MI Control MI/Control
Cui Y/2013 STEMI/NSTEMI Health Flow cytometry 105/mL 40/20
Del Turco S/2008 MI Health Flow cytometry 106/L 46/10
Leong H S/2011 AMI Health Flow cytometry /µL 6/5
Matsumoto N/2004 ACS Health Flow cytometry 104/platelet count 41/20
Michelsen A E/2008 MI Health BCA Protein Assay µg/L 61/61
Min P K/2013 STEMI Health ELISA nM (phosphatidylserine equivalent) 45/16
Morel O/2004 STEMI Health ELISA nM (PhtdSer equivalent) 50/50
Morel O/2005 STEMI Health ELISA nM (PhtdSer equivalent) 9/50
Skeppholm M/2012 STEMI/NSTEMI Health Flow cytometry 106/L 51/61
Stepien E/2012 AMI Health Flow cytometry /µL 12/9
Tan K T/2005 ACS Health Flow cytometry 105/mL 54/35
Quality Index

The majority of studies scored highly on reporting of the interventions used and outcome measures. Only one report scored lowly on the small sample size. The average score of all studies was 15.8 (Table 2).

Quality Index of included studies
Author/Year Quality Index
Cui Y/2013 16
Del Turco S/2008 16
Leong H S/2011 14
Matsumoto N/2004 16
Michelsen A E/2008 16
Min P K/2013 16
Morel O/2004 16
Morel O/2005 16
Skeppholm M/2012 16
Stepien E/2012 16
Tan K T/2005 16
Annexin V+ microvesicles in health control and patients with myocardial infarction

Four of the eleven studies showed changes in AMVs levels between patients with myocardial infarction and healthy controls. In three of these reports, AMVs levels in patients with myocardial infarction were higher than healthy controls. Only in one study, patients with myocardial infarction did not differ from healthy controls concerning AMVs levels. When results of all studies were combined, there was a significant difference between groups with higher AMVs levels in patients with a myocardial infarction [SMD = 3.65, 95% CI (1.03, 6.27), Z = 2.73 (p < 0.00001; Figure 2A)]. Furthermore, there was significant statistical heterogeneity across studies (χ2= 95.64, df = 3, p < 0.00001, I2= 97%). As shown in Figure 2B, no publication bias was found.

The forest plot (A) and funnel plot (B) of meta-analysis of Annexin V+ microvesicles in myocardial infarction.

Platelet microvesicles in health control and patients with myocardial infarction

All of eleven studies found PMVs levels varied between myocardial infarction patients and healthy controls. Nine studies reported that level of PMVs were higher in MI patients, whereas the other studies showed no difference in groups. Combining the results of all studies, it was significantly increased in myocardial infarction patients [SMD = 2.88, 95% CI (1.82, 3.93), Z = 5.35 (p < 0.00001; Figure 3A)]. There was also significant statistical heterogeneity across studies (χ2= 235.02, df = 10, p < 0.00001, I2= 96%). As shown in Figure 3B, a little publication bias was found.

The forest plot (A) and funnel plot (B) meta-analysis of platelet microvesicles in myocardial infarction.

Endothelial microvesicles in health control and patients with myocardial infarction

Six of the eleven studies reported alternation in EMVs levels between the two groups. Four reports concluded that a proportion of MI patients have elevated EMVs levels. But the other studies showed no significant difference. Combining all results of those studies, MI patients had a higher level of EMVs. [SMD = 2.73, 95% CI (1.13, 4.34), Z = 3.33 (p = 0.0009; Figure 4A)]. The statistical heterogeneity was significant across studies (χ2= 155.28, df = 6, p < 0.00001, I2= 96%). As shown in Figure 4B, no publication bias was found.

The forest plot (A) and funnel plot (B) meta-analysis of endothelial microvesicles in myocardial infarction.

Leukocyte microvesicles in health control and patients with myocardial infarction

Five of the eleven studies exhibited differences in LMVs levels between myocardial infarction patients and health controls. Four reports showed that LMVs levels in myocardial infarction patients were higher than health controls. The finding of one report was, however, in the opposite direction, with patients having significantly lower LMVs levels than controls. When results of all studies were combined, there was no significant difference between the two groups [SMD = 0.73, 95% CI (-0.57, 2.03), Z = 1.11 (p = 0.27; Figure 5A)]. There was also significant statistical heterogeneity across studies (χ2= 90.69, df = 4, p < 0.00001, I2= 96%). As shown in Figure 5B, no publication bias was found.

The forest plot (A) and funnel plot (B) meta-analysis of leukocyte microvesicles in myocardial infarction.

Discussion

We conducted an exhaustive search to identify studies related to our question and gave the most comprehensive overview of MVs in MI to date. Systematic methods were applied to reduce bias in the identification of studies, data extraction and synthesis, and appraisal of study quality. This meta-analysis showed that higher level of AMVs, PMVs and EMVs in peripheral blood might be associated with patients with MI, indicating that these MVs may be helpful in the diagnosis of MI. However, the result of LMVs was negative.

Microvesicles (MVS) or microparticles (MPS) have relationship not only with inflamatory and thrombotic processes but with tissue regenerative process and angiogenesis, which can be a protective function. In addition, MVS can be a signaler of homeostasis balancing cell stimulus and apoptosis. Diabetic patients have increased release of MVS and this can be a biomarker of diabetic progression by retinopathy. Pharmacologic approach is helpful because of endothelial dysfunction. Renin-angiotensin system blocker and calcium channel blocker may be good options in type 2 diabetes mellitus.21 Pinheiro et al.22 have assessed the effect of the antiplatelet drug clopidogrel in association or not with rosuvastatin (40 mg) on the levels of EMP and PMP in patients with stable coronary disease on statins for at least three months. Those authors have identified an increase in the levels of PMP after suspension of rosuvastatina and maintenance of only clopidogrel for four weeks and a tendency towards greater release of EMP in those patients. They have suggested that an increase in the apoptosis of platelets occurred, and that rosuvastatin might have a protective effect on the endothelium when associated with clopidogrel.22 In a similar study, França et al.23 have assessed the influence of atorvastatin (80 mg) in association or not with clopidogrel in patients with stable coronary disease. Those authors have suggested higher vascular stability promoted by atorvastatin after identifying an inverse relationship between the plasma concentration of atorvastatin and the levels of PMP.23

MVs have a bilayered phospholipid membrane.24 The presence of externalized PS on MVs surfaces indicates an altered phospholipid distribution profile compared to the plasma membrane of a resting mammalian cell. Additionally, the molecules present in the outer surface, once defined, provide accessible markers for detecting and characterizing MVs using molecular probes.25 AMVs express phosphatidylserine (PS) in their surface and are currently defined as apoptotic MVs. It is shown that AMVs levels were significantly higher in patients with MI than healthy controls. It is likely due to the myocardial ischemia and hypoxia which make cell apoptosis, thereby releasing large amounts of AMVs. In each case, the variation in AMVs levels shows that cell apoptosis occurs. A in vitro study uncovered that MVs extracted from the circulating blood of a patient with myocardial infarction and applied to the isolated aortic rings of a rat, led to severely damage of endothelial function.26 Thus, the high level of AMVs and their effect may be the cause the further progression of myocardial infarction.

PMVs are defined as membranous vesicles derived from the platelet which are defined and identified by surface molecules CD62P and CD63.27 With the ability to bind coagulation factors VIII, Va, and IX, PMVs not only reflect platelet activation but also contribute to the activation of the coagulation pathway and thrombogenesis.28-29 It was found that there was high level of PMVs in the peripheral blood of the MI patients. The main cause may be the change of blood flow shear force induced by pathological changes in the blood vessels of the MI patients. These changes promote the aggregation and activation of platelets, thereby leading to the generation of a large number of PMVs. This suggests that increased PMVs may be further expanded by the coagulation reaction of the blood vessels in the MI patients.

The dysfunction of endothelial cells plays an important role in the MI. EMVs are sub-cellular membrane vesicles released from endothelial cell during activation or apoptosis.30 EMVs carry specific markers which originate from the maternal cells, including CD31, CD51, CD54, CD62E, CD105, CD144 or CD146. It is found that EMVs were significantly higher in the MI group. His could be because of the dysfunction of endothelial cells, which release lots of EMVs into the blood. When the EMVs were incubated with human umbilical vein endothelial cells (HUVECs), endothelial cells proliferation decreased and their apoptosis increased, then the capacity of angiogenesis went down dramatically.31 The high level of EMVs is considered as a cause to worsen the condition by inducing endothelial dysfunction on the MI states.

Unlike the single source of EMVs or PMVs, LMVs may originate from neutrophils, monocytes/macrophages, and lymphocytes.32 They also express markers from their parental cells. Various antibodies were used to capture LMVs, including CD4, CD14, CD11a and so on. Combined with the clinical results, this meta-analysis found that there was no significant variation in LMVs’ level between the health controls and patients with MI. But the studies that used CD4 and CD14 antibodies, shown LMVs’ level was higher in patients with MI. When CD11a antibody was used, a muddle of contradictory results was found. Therefore, additional studies are needed to further investigate the level of LMVs in MI. Meanwhile, LMVs measurement still requires elaborate techniques because of its lack of standardization.

Limitations of this meta-analysis must be considered. First, the quality of individual studies was not always optimal, as shown by the general lack of information on some studies. So we used simple and elementary inequalities in order to estimate the mean and the variance for such studies. But it is not exactly enough. Second, there is heterogeneity of SMD across studies, corresponding in part to heterogeneity in study definitions. Third, although the quality of included studies was judged overall to be adequate, the findings in the present study need to be interpreted with caution, given that not all studies reported on potential confounding variables and their adjustment in analyses. Finally, meta-analytic data also need to be cautiously interpreted, given the substantial heterogeneity among studies.

 Conclusion

This meta-analysis showed that higher level of AMVs, PMVs and EMVs in peripheral blood may be associated with patients with MI, indicating that these MVs may be helpful in the diagnosis of MI. However, the result of LMVs was negative.

Sources of Funding

This study was funded by National Natural Science Foundation of China through grant n°. 81602496; Science and Technology Foundation of Administration of Traditional Chinese Medicine of Tianjin, China, nos 2015022 and 13047; Science and Technology Foundation of Tianjin Municipal Commission of Health and Family planning, n°. 2013KZ054.

Study Association

This study is not associated with any thesis or dissertation work.

 References 1 Dahlof B. Cardiovascular disease risk factors: epidemiology and risk assessment. Am J Cardiol. 2010;105(1 Suppl):3A-9A. Dahlof B Cardiovascular disease risk factors: epidemiology and risk assessment Am J Cardiol 2010 105 1 Suppl 3A 9A 2 Mastronardi ML, Mostefai HA, Meziani F, Martinez MC, Asfar P, Andriantsitohaina R. Circulating microparticles from septic shock patients exert differential tissue expression of enzymes related to inflammation and oxidative stress. Crit Care Med 2011;39(7):1739-48. Mastronardi ML Mostefai HA Meziani F Martinez MC Asfar P Andriantsitohaina R Circulating microparticles from septic shock patients exert differential tissue expression of enzymes related to inflammation and oxidative stress Crit Care Med 2011 39 7 1739 1748 3 Boulanger CM, Scoazec A, Ebrahimian T, Henry P, Mathieu E, Tedgui A, et al. Circulating microparticles from patients with myocardial infarction cause endothelial dysfunction. Circulation. 2001;104(22):2649-52. Boulanger CM Scoazec A Ebrahimian T Henry P Mathieu E Tedgui A Circulating microparticles from patients with myocardial infarction cause endothelial dysfunction Circulation 2001 104 22 2649 2652 4 Mezentsev A, Merks RM, O'Riordan E, Chen J, Mendelev N, Goligorsky MS, et al. Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress. Am J Physiol Heart Circ Physiol. 2005;289(3):H1106-14. Mezentsev A Merks RM O'Riordan E Chen J Mendelev N Goligorsky MS Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress Am J Physiol Heart Circ Physiol 2005 289 3 H1106 H1114 5 Bernal-Mizrachi L, Jy W, Jimenez JJ, Pastor J, Mauro LM, Horstman LL, et al. High levels of circulating endothelial microparticles in patients with acute coronary syndromes. Am Heart J. 2003;145(6):962-70. Bernal-Mizrachi L Jy W Jimenez JJ Pastor J Mauro LM Horstman LL High levels of circulating endothelial microparticles in patients with acute coronary syndromes Am Heart J 2003 145 6 962 970 6 Bulut D, Maier K, Bulut-Streich N, Borgel J, Hanefeld C, Mugge A. Circulating endothelial microparticles correlate inversely with endothelial function in patients with ischemic left ventricular dysfunction. J Card Fail. 2008;14(4):336-40. Bulut D Maier K Bulut-Streich N Borgel J Hanefeld C Mugge A Circulating endothelial microparticles correlate inversely with endothelial function in patients with ischemic left ventricular dysfunction J Card Fail 2008 14 4 336 340 7 Zielinska M, Koniarek W, Goch JH, Cebula B, Tybura M, Robak T, Smolewski P. Circulating endothelial microparticles in patients with acute myocardial infarction. Kardiol Pol. 2005;62(6):531-42. Zielinska M Koniarek W Goch JH Cebula B Tybura M Robak T Smolewski P Circulating endothelial microparticles in patients with acute myocardial infarction Kardiol Pol 2005 62 6 531 542 8 van der Zee PM, Biro E, Ko Y, de Winter RJ, Hack CE, Sturk A, Nieuwland R. P-selectin- and CD63-exposing platelet microparticles reflect platelet activation in peripheral arterial disease and myocardial infarction. Clin Chem. 2006;52(4):657-64. van der Zee PM Biro E Ko Y de Winter RJ Hack CE Sturk A Nieuwland R P-selectin- and CD63-exposing platelet microparticles reflect platelet activation in peripheral arterial disease and myocardial infarction Clin Chem 2006 52 4 657 664 9 Cui Y, Zheng L, Jiang M, Jia R, Zhang X, Quan Q, et al. Circulating microparticles in patients with coronary heart disease and its correlation with interleukin-6 and C-reactive protein. Mol Biol Rep. 2013;40(11):6437-42. Cui Y Zheng L Jiang M Jia R Zhang X Quan Q Circulating microparticles in patients with coronary heart disease and its correlation with interleukin-6 and C-reactive protein Mol Biol Rep 2013 40 11 6437 6442 10 Min PK, Kim JY, Chung KH, Lee BK, Cho M, Lee DL, et al. Local increase in microparticles from the aspirate of culprit coronary arteries in patients with ST-segment elevation myocardial infarction. Atherosclerosis. 2013;227(2):323-8. Min PK Kim JY Chung KH Lee BK Cho M Lee DL Local increase in microparticles from the aspirate of culprit coronary arteries in patients with ST-segment elevation myocardial infarction Atherosclerosis 2013 227 2 323 328 11 Skeppholm M, Mobarrez F, Malmqvist K, Wallen H. Platelet-derived microparticles during and after acute coronary syndrome. Thromb Haemost. 2012;107(6):1122-9. Skeppholm M Mobarrez F Malmqvist K Wallen H Platelet-derived microparticles during and after acute coronary syndrome Thromb Haemost 2012 107 6 1122 1129 12 Stepien E, Stankiewicz E, Zalewski J, Godlewski J, Zmudka K, Wybranska I. Number of microparticles generated during acute myocardial infarction and stable angina correlates with platelet activation. Arch Med Res. 2012;43(1):31-5. Stepien E Stankiewicz E Zalewski J Godlewski J Zmudka K Wybranska I Number of microparticles generated during acute myocardial infarction and stable angina correlates with platelet activation Arch Med Res 2012 43 1 31 35 13 Leong HS, Podor TJ, Manocha B, Lewis JD. Validation of flow cytometric detection of platelet microparticles and liposomes by atomic force microscopy. J Thromb Haemost. 2011;9(12):2466-76. Leong HS Podor TJ Manocha B Lewis JD Validation of flow cytometric detection of platelet microparticles and liposomes by atomic force microscopy J Thromb Haemost 2011 9 12 2466 2476 14 Del Turco S, Basta G, Lazzerini G, Evangelista M, Rainaldi G, Tanganelli P, et al. Effect of the administration of n-3 polyunsaturated fatty acids on circulating levels of microparticles in patients with a previous myocardial infarction. Haematologica. 2008;93(6):892-9. Del Turco S Basta G Lazzerini G Evangelista M Rainaldi G Tanganelli P Effect of the administration of n-3 polyunsaturated fatty acids on circulating levels of microparticles in patients with a previous myocardial infarction Haematologica 2008 93 6 892 899 15 Morel O, Jesel L, Freyssinet JM, Toti F. Elevated levels of procoagulant microparticles in a patient with myocardial infarction, antiphospholipid antibodies and multifocal cardiac thrombosis. Thromb J. 2005;3:15. Morel O Jesel L Freyssinet JM Toti F Elevated levels of procoagulant microparticles in a patient with myocardial infarction, antiphospholipid antibodies and multifocal cardiac thrombosis Thromb J 2005 3 15 15 16 Tan KT, Tayebjee MH, Macfadyen RJ, Lip GY, Blann AD. Elevated platelet microparticles in stable coronary artery disease are unrelated to disease severity or to indices of inflammation. Platelets. 2005;16(6):368-71. Tan KT Tayebjee MH Macfadyen RJ Lip GY Blann AD Elevated platelet microparticles in stable coronary artery disease are unrelated to disease severity or to indices of inflammation Platelets 2005 16 6 368 371 17 Morel O, Hugel B, Jesel L, Mallat Z, Lanza F, Douchet MP, et al. Circulating procoagulant microparticles and soluble GPV in myocardial infarction treated by primary percutaneous transluminal coronary angioplasty: a possible role for GPIIb-IIIa antagonists. J Thromb Haemost. 2004;2(7):1118-26. Morel O Hugel B Jesel L Mallat Z Lanza F Douchet MP Circulating procoagulant microparticles and soluble GPV in myocardial infarction treated by primary percutaneous transluminal coronary angioplasty: a possible role for GPIIb-IIIa antagonists J Thromb Haemost 2004 2 7 1118 1126 18 Matsumoto N, Nomura S, Kamihata H, Kimura Y, Iwasaka T. Increased level of oxidized LDL-dependent monocyte-derived microparticles in acute coronary syndrome. Thromb Haemost. 2004;91(1):146-54. Matsumoto N Nomura S Kamihata H Kimura Y Iwasaka T Increased level of oxidized LDL-dependent monocyte-derived microparticles in acute coronary syndrome Thromb Haemost 2004 91 1 146 154 19 Michelsen AE, Brodin E, Brosstad F, Hansen JB. Increased level of platelet microparticles in survivors of myocardial infarction. Scand J Clin Lab Invest. 2008;68(5):386-92. Michelsen AE Brodin E Brosstad F Hansen JB Increased level of platelet microparticles in survivors of myocardial infarction Scand J Clin Lab Invest 2008 68 5 386 392 20 Hozo SP, Djulbegovic B, Hozo I. Estimating the mean and variance from the median, range, and the size of a sample. BMC Med Res Methodol 2005;5:13. Hozo SP Djulbegovic B Hozo I Estimating the mean and variance from the median, range, and the size of a sample BMC Med Res Methodol 2005 5 13 13 21 França CN, Izar MC, Amaral JB, Tegani DM, Fonseca FA. Microparticles as potential biomarkers of cardiovascular disease. Arq Bras Cardiol. 2015;104(2):169-74. França CN Izar MC Amaral JB Tegani DM Fonseca FA Microparticles as potential biomarkers of cardiovascular disease Arq Bras Cardiol 2015 104 2 169 174 22 Pinheiro LF, França CN, Izar MC, Barbosa SP, Bianco HT, Kasmas SH, et al. Pharmacokinetic interactions between clopidogrel and rosuvastatin: effects on vascular protection in subjects with coronary heart disease. Int J Cardiol. 2012;158(1):125-9. Pinheiro LF França CN Izar MC Barbosa SP Bianco HT Kasmas SH Pharmacokinetic interactions between clopidogrel and rosuvastatin: effects on vascular protection in subjects with coronary heart disease Int J Cardiol 2012 158 1 125 129 23 França CN, Pinheiro LF, Izar MC, Brunialti MK, Salomão R, Bianco HT, et al. Endothelial progenitor cell mobilization and platelet microparticle release are influenced by clopidogrel plasma levels in stable coronary artery disease. Circ J. 2012;76(3):729-36. França CN Pinheiro LF Izar MC Brunialti MK Salomão R Bianco HT Endothelial progenitor cell mobilization and platelet microparticle release are influenced by clopidogrel plasma levels in stable coronary artery disease Circ J 2012 76 3 729 736 24 Morel O, Jesel L, Freyssinet JM, Toti F. Cellular mechanisms underlying the formation of circulating microparticles. Arterioscler Thromb Vasc Biol. 2011;31(1):15-26. Morel O Jesel L Freyssinet JM Toti F Cellular mechanisms underlying the formation of circulating microparticles Arterioscler Thromb Vasc Biol 2011 31 1 15 26 25 Gyorgy B, Szabo TG, Pasztoi M, Pal Z, Misjak P, Aradi B, et al. Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles. Cell Mol Life Sci. 2011;68(16):2667-88. Gyorgy B Szabo TG Pasztoi M Pal Z Misjak P Aradi B Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles Cell Mol Life Sci 2011 68 16 2667 2688 26 Boulanger CM, Scoazec A, Ebrahimian T, Henry P, Mathieu E, Tedgui A, et al. Circulating microparticles from patients with myocardial infarction cause endothelial dysfunction. Circulation. 2001;104(22):2649-52. Boulanger CM Scoazec A Ebrahimian T Henry P Mathieu E Tedgui A Circulating microparticles from patients with myocardial infarction cause endothelial dysfunction Circulation 2001 104 22 2649 2652 27 Zwicker JI, Lacroix R, Dignat-George F, Furie BC, Furie B. Measurement of platelet microparticles. Methods Mol Biol. 2012;788:127-39. Zwicker JI Lacroix R Dignat-George F Furie BC Furie B Measurement of platelet microparticles Methods Mol Biol 2012 788 127 139 28 Morel O, Morel N, Freyssinet JM, Toti F. Platelet microparticles and vascular cells interactions: a checkpoint between the haemostatic and thrombotic responses. Platelets. 2008;19(1):9-23. Morel O Morel N Freyssinet JM Toti F Platelet microparticles and vascular cells interactions: a checkpoint between the haemostatic and thrombotic responses Platelets 2008 19 1 9 23 29 Sinauridze EI, Kireev DA, Popenko NY, Pichugin AV, Panteleev MA, Krymskaya OV, et al. Platelet microparticle membranes have 50- to 100-fold higher specific procoagulant activity than activated platelets. Thromb Haemost. 2007;97(3):425-34. Sinauridze EI Kireev DA Popenko NY Pichugin AV Panteleev MA Krymskaya OV Platelet microparticle membranes have 50- to 100-fold higher specific procoagulant activity than activated platelets Thromb Haemost 2007 97 3 425 434 30 Dignat-George F, Boulanger CM. The many faces of endothelial microparticles. Arterioscler Thromb Vasc Biol. 2011;31(1):27-33. Dignat-George F Boulanger CM The many faces of endothelial microparticles Arterioscler Thromb Vasc Biol 2011 31 1 27 33 31 Mezentsev A, Merks RM, O'Riordan E, Chen J, Mendelev N, Goligorsky MS, et al. Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress. Am J Physiol Heart Circ Physiol. 2005;289(3):H1106-14. Mezentsev A Merks RM O'Riordan E Chen J Mendelev N Goligorsky MS Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress Am J Physiol Heart Circ Physiol 2005 289 3 H1106 H1114 32 Angelillo-Scherrer A. Leukocyte-derived microparticles in vascular homeostasis. Circ Res. 2012;110(2):356-69. Angelillo-Scherrer A Leukocyte-derived microparticles in vascular homeostasis Circ Res 2012 110 2 356 369 Artigo de Revisão Uma Meta-Análise de Microvesículas Circulantes em Pacientes com Infarto do Miocárdio Wang Zhida 1 Cai Wang 2 Hu Shaolan 1 Xia Yufei 3 Wang Yao 4 Zhang Qi 5 Chen Liming 1 Key Laboratory of Hormones and Development (Ministry of Health) - Tianjin Key Laboratory of Metabolic Diseases* - Tianjin Metabolic Diseases Hospital & Tianjin Institute of Endocrinology# - Tianjin Medical University, Tianjin - China Department of Surgery* - Tianjin Nankai Hospital - Tianjin Medical University, Tianjin, China# School of Nursing - Tianjin Medical University, Tianjin - China Department of Pharmacology - School of Basic Medical Science - Tianjin Medical University, Tianjin - China Institute of Integrative Medicines for Acute Abdominal Diseases - Nankai Hospital, Tianjin - China Correspondência: Qi Zhang*; Liming Chen* Institute of Integrative Medicines for Acute Abdominal Diseases-Nankai Hospital, Tianjin-China (Qi Zhang); Hormones and Development (Ministry of Health)-Tianjin Key Laboratory of Metabolic Diseases-Tianjin Metabolic Diseases Hospital & Tianjin Institute of Endocrinology - Tianjin Medical University,Tianjin-China (Liming Chen). E-mail: zhangqi8501@126.com; xfx22081@vip.163.com

Zhida Wang e Wang Cai contribuíram igualmente e são os primeiros autores;

Qi Zhang e Liming Chen contribuíram igualmente e são os autores correspondentes

Contribuição dos autores

Concepção e desenho da pesquisa e Redação do manuscrito: Wang Z, Cai W; Obtenção de dados: Hu S; Análise e interpretação dos dados: Xia Y; Análise estatística: Wang Y; Obtenção de financiamento e Revisão crítica do manuscrito quanto ao conteúdo intelectual importante: Zhang Q, Chen L.

Potencial conflito de interesses

Declaro não haver conflito de interesses pertinentes.

 Resumo Fundamentos:

As microvesículas derivadas de células (MVs) são vesículas liberadas de células ativadas ou apoptóticas. No entanto, os níveis de MVs no infarto do miocárdio foram encontrados inconsistentes nas pesquisas.

 Objetivo:

Avaliar a associação entre MV e infarto do miocárdio por meio de uma meta-análise.

 Métodos:

Foi realizada uma pesquisa sistemática na literatura em PubMed, Embase, Cochran e no banco de dados eletrônico do Google Scholar. Uma comparação dos níveis de MV entre pacientes com infarto do miocárdio e pessoas saudáveis foi incluída no nosso estudo. A Diferença Média Padrão (DMP) e o intervalo de confiança (IC) de 95% nos grupos foram calculadas e meta-analisadas.

 Resultados:

Foram incluídos 11 estudos com um total de 436 participantes. Em comparação com as pessoas saudáveis, as MVA [DMP = 3,65, IC 95% (1,03, 6,27)], MVPs [DMP = 2,88, IC 95% (1,82, 3,93)] e MVEs [DMP = 2,73, IC 95% (1,13, 4.34)], foram maiores em pacientes com infarto do miocárdio. No entanto, os níveis de MVL [DMP = 0,73, IC 95% (-0,57, 2,03)] não foram alterados significativamente em pacientes com infarto do miocárdio.

 Conclusões:

MVAs, MVPs e MVEs podem ser biomarcadores potenciais para o infarto do miocárdio.

Palavras-chave: Infarto do Miocárdio Micropartículas Derivadas de Células Anexina A5 Plaquetas Leucócitos Endotélio Introdução

A doença cardíaca isquêmica (DIC) é uma das doenças cardiovasculares que prejudica a saúde humana.1 Aterotrombose, disfunção endotelial e apoptose celular estão na base patológica nestas doenças. Os estudos relevantes nesta área sugerem que as microvesículas derivadas de células (MVs) estão relacionadas com a ativação plaquetária, danos endoteliais e inflamação associada à existência de fatores de risco cardiovasculares.2-4 Uma vez que eles estão envolvidos no processo fisiopatológico de doenças, a atenção tem sido focada na relação entre MVs e infarto do miocárdio (IM).5-8 Evidências crescentes implicam que MVs podem ser consideradas como biomarcadores ou mediadores novos úteis na compreensão dos mecanismos das doenças cardiovasculares.

As MVs são utilizadas para descrever uma população de vesículas subcelulares liberadas da membrana plasmática durante a ativação ou apoptose das células e identificadas por um intervalo de tamanhos de 100 nm a 1,0 µm de diâmetro. MVs constituem uma população heterogênea, diferente em origem celular, números, tamanho, composição antigênica e propriedades funcionais. Alterações nas quantidades de diferentes MVs derivadas de células podem fornecer informações sobre as alterações fisiopatológicas. Embora muitos estudos tenham demonstrado que o infarto do miocárdio está associado às MVs, a informação obtida mostra resultados heterogêneos, com alta variação quanto ao tamanho da MV, ao tipo de MV, aos níveis de MV, aos critérios de inclusão e aos métodos. Assim, realizou-se uma meta-análise das alterações de MVs de anexina V positiva (MVAs), MVs de plaquetas (MVPs), MVs endoteliais (MVEs) e MV de leucócitos (MVLs) em pacientes com infarto do miocárdio e pessoas saudáveis.

 Métodos Fontes de dados e pesquisas

Pesquisamos as bases de dados de MEDLINE (pubmed), Embase, Cochrane e Google Scholar para artigos de 2000 a 2013. Todas as buscas foram aplicadas com os seguintes títulos médicos: "infarto do miocárdio", "intervenção coronária percutânea primária", "stenting", "angioplastia com balão", "síndrome coronariana aguda" ou "isquemia coronária", "micropartículas", "micropartículas derivadas de células", "micropartículas em circulação", "microvesículas". Essas pesquisas foram restritas a publicações limitadas à pesquisa em seres humanos. Uma pesquisa manual para referências citadas nos estudos publicados e artigos de revisão relevantes também foi realizada para identificar investigações adicionais adequadas para o nosso propósito. Para estudos não publicados e publicados que não foram divulgados exaustivamente, foi feita a tentativa por e-mail para contatar os investigadores principais, a fim de recuperar os dados em falta. Finalmente, especialistas conhecidos nesta área foram contatados para garantir que todos os dados relevantes foram extraídos.

 Seleção de Estudos

Dois de nós realizamos a identificação de resumos relevantes e a seleção de estudos com base nos critérios descritos abaixo em forma independente, e um terceiro investigador resolveu qualquer discrepância. Foram selecionados estudos comparando os níveis de diferentes MVs: total, plaquetário, endotelial, leucocitário entre pessoas saudáveis e pacientes com infarto do miocárdio.

Os estudos foram incluídos se preenchessem os seguintes critérios: (i) Estudo intitulado MV circulante correlacionado com IM; (ii) O desenho do estudo foi estudo de caso-controle ou estudo de coorte; (iii) O IM como um subgrupo de investigação que extrai de forma independente informação relevante sobre IM. Excluímos o seguinte: (i) Revisão; (ii) Texto não completo, apenas um resumo; iii) Ensaio em animais.

 Extração e síntese de dados

Extraímos informações, incluindo estudo e características da população, tamanho da amostra, desenho do estudo e resultados relevantes para este estudo. Médias e desvios padrão dos níveis de MVs foram extraídos. Quando um artigo obedecia aos critérios de inclusão, mas não dispunha de informações sobre parâmetros para análise, ou quando os resultados foram relatados, mas não relacionados ao infarto do miocárdio, contatamos os autores para obter dados brutos. A qualidade dos estudos foi avaliada utilizando a lista de verificação Downs e Black.

 Análise estatística

Os dados foram analisados utilizando o software estatístico RevMan 5.0 fornecido pela Cochrane Collaboration. DMP e 95% de IC foram utilizados como estimativas sumárias. A presença de heterogeneidade entre os estudos foi testada com o teste de heterogeneidade χ² e a estatística de I². Heterogeneidade foi significativa quando p < 0,05 ou I² foi superior a 50%. Foi utilizado um modelo de efeitos aleatórios em todas as análises para testar a estabilidade dos resultados à escolha do modelo estatístico. Se houver heterogeneidade significativa, são utilizados os resultados do modelo de efeitos aleatórios. Definimos a priori a análise de sensibilidade de estudos de alta qualidade para cada resultado clínico. O potencial de viés de publicação foi avaliado utilizando a abordagem do gráfico de funil.

 Resultados Resultados da Busca

Foram analisados 172 artigos identificados a partir da MEDLINE (pubmed), Embase, Cochrane e Google Scholar; E, em seguida, 140 foram excluídos com base no título e resumo. Após uma avaliação detalhada da elegibilidade potencial, 11 estudos preencheram todos os critérios de inclusão e foram recuperados para meta-análise.9-19 O fluxograma de ensaio está resumido na Figura 1.

Diagrama de fluxo da estratégia de busca e seleção do estudo

Características básicas dos estudos

As características de todos os estudos incluídos estão apresentadas na Tabela 1. Estes estudos foram publicados de 2004 a 2013. O tamanho da amostra variou de 5 a 61. Um total de 436 participantes (186 controles saudáveis e 250 pacientes com IM) foram incluídos. Entre estes estudos, os resultados dos MVs foram expressos de forma diferente. Seis relatórios foram expressos como o número de MVs no plasma por microlitro, mililitro e litro. Três relatórios foram expressos como PS eq (equivalentes de fosfatidilserina), um relatório foi expresso como número de MVs na contagem de plaquetas e um relatório foi expresso como concentrações plasmáticas de MVs. Houve quatro relatórios que só informavam a mediana, alcance e tamanho do ensaio. Para estimar a média e a variância desses artigos, utilizamos o número de desigualdades amostrais e elementares.20

Características dos estudos incluídos
Autor/Ano Objeto de estudo Método de medição de MVs Unidades de MVs Tamanho da amostra
IM Controle IM/Controle
Cui Y/2013 STEMI/NSTEMI Saúde Citometría de fluxo 105/mL 40/20
Del Turco S/2008 IM Saúde Citometría de fluxo 106/L 46/10
Leong H S/2011 IAM Saúde Citometría de fluxo /µL 6/5
Matsumoto N/2004 SCA Saúde Citometría de fluxo 104/ contagem de plaquetas 41/20
Michelsen A E/2008 IM Saúde Proteína BCA Ensaio de Proteínas µg/L 61/61
Min P K/2013 STEMI Saúde ELISA nM (equivalente fosfatidilserina) 45/16
Morel O/2004 STEMI Saúde ELISA nM (Equivalente PhtdSer) 50/50
Morel O/2005 STEMI Saúde ELISA nM (Equivalente PhtdSer) 9/50
Skeppholm M/2012 STEMI/NSTEMI Saúde Citometría de fluxo 106/L 51/61
Stepien E/2012 IAM Saúde Citometría de fluxo /µL 12/9
Tan K T/2005 SCA Saúde Citometría de fluxo 105/mL 54/35
Índice de Qualidade

A maioria dos estudos obteve alta pontuação na notificação das intervenções utilizadas e nas medidas de resultados. Apenas um relatório teve pontuações baixas pelo pequeno tamanho da amostra. A pontuação média de todos os estudos foi de 15,8 (Tabela 2).

Índice de qualidade dos estudos incluídos
Autor/Ano Índice de Qualidade
Cui Y/2013 16
Del Turco S/2008 16
Leong H S/2011 14
Matsumoto N/2004 16
Michelsen A E/2008 16
Min P K/2013 16
Morel O/2004 16
Morel O/2005 16
Skeppholm M/2012 16
Stepien E/2012 16
Tan K T/2005 16
Microvesículas Anexina V + no controle da saúde e pacientes com infarto do miocárdio

Quatro dos onze estudos mostraram alterações nos níveis de MVA entre pacientes com infarto do miocárdio e controles saudáveis. Em três destes relatórios, os níveis de MVA em pacientes com infarto do miocárdio foram superiores aos controles saudáveis. Apenas em um estudo, os pacientes com infarto do miocárdio não diferiram dos controles saudáveis em relação aos níveis de MVAs. Quando os resultados de todos os estudos foram combinados, houve uma diferença significativa entre os grupos com níveis mais elevados de MVA em pacientes com infarto do miocárdio [DMP = 3,65, 95% IC (1,03, 6,27), Z = 2,73 (p < 0,00001; Figura 2A)]. Além disso, houve heterogeneidade estatística significativa entre os estudos (χ2= 95,64, df = 3, p < 0,00001, I2= 97%). Como é mostrado na Figura 2B, não foi encontrado viés de publicação.

O gráfco de meta-análise (A) e o gráfco de funil (B) da meta-análise das microvesículas de anexina V + no infarto do miocárdio.

Microvesículas de plaquetas no controle da saúde e pacientes com infarto do miocárdio

Todos os onze estudos encontraram níveis de MVPs variados entre pacientes com infarto do miocárdio e controles saudáveis. Nove estudos relataram que o nível de MVPs foi maior em pacientes com IM, enquanto que os outros estudos não mostraram diferença em grupos. Combinando os resultados de todos os estudos, o nível de MVP estava significativamente aumentado em pacientes com infarto do miocárdio [DMP = 2,88, 95% IC (1,82, 3,93), Z = 5,35 (p < 0, 00001, Figura 3A)]. Houve também heterogeneidade estatística significativa entre os estudos (χ2 = 235,02, df = 0, p < 0,00001, I2 = 96%). Conforme é ilustrado na Figura 3B, foi encontrado um pequeno viés de publicação.

O gráfco de meta-análise (A) e o gráfco de funil (B) da meta-análise de microvesículas de plaquetas no infarto do miocárdio.

Microvesículas endoteliais no controle da saúde e pacientes com infarto do miocárdio

Seis dos onze estudos relataram alternância nos níveis de MVEs entre os dois grupos. Quatro relatórios concluíram que uma proporção de pacientes com IM apresentam níveis elevados de MVEs. Mas os outros estudos não mostraram diferença significativa. Combinando todos os resultados desses estudos, os pacientes com IM apresentaram maior nível de MVEs. [DMP = 2,73, 95% IC (1,13, 4,34), Z = 3,33 (p = 0,0009, Figura 4A)]. A heterogeneidade estatística foi significativa entre os estudos (χ2 = 155,28, df = 6, p < 0,00001, I2= 96%). Conforme ilustrado na Figura 4B, não foi encontrado qualquer viés de publicação.

O gráfco de meta-análise (A) e o gráfco de funil (B) da meta-análise de microvesículas endoteliais no infarto do miocárdio.

Microvesículas de leucócitos no controle da saúde e pacientes com infarto do miocárdio

Cinco dos onze estudos exibiram diferenças nos níveis de MVLs entre pacientes com infarto do miocárdio e controles de saúde. Quatro relatórios mostraram que os níveis de MVLs em pacientes com infarto do miocárdio foram superiores aos controles de saúde. O achado de um relatório foi, contudo, na direção oposta, com pacientes com níveis de MVLs significativamente menores do que os controles. Quando os resultados de todos os estudos foram combinados, não houve diferença significativa entre os dois grupos [DMP = 0,73, IC 95% (-0,57; 2,03), Z = 1,11 (p = 0,27; Figura 5A)]. Houve também heterogeneidade estatística significativa entre os estudos (χ2= 90,69, df = 4, p < 0,00001, I2= 96%). Conforme é ilustrado na Figura 5B, não foi encontrado qualquer viés de publicação.

O gráfco de meta-análise (A) e o gráfco de funil (B) da meta-análise de microvesículas de leucócitos no infarto do miocárdio.

Discussão

Realizamos uma exaustiva pesquisa para identificar os estudos relacionados à nossa pergunta e apresentamos a visão mais abrangente das MVs no IM até a data. Métodos sistemáticos foram aplicados para reduzir o viés na identificação de estudos, extração e síntese de dados e avaliação da qualidade do estudo. Esta meta-análise mostrou que níveis mais elevados de MVAs, MVPs e MVEs no sangue periférico podem estar associados a pacientes com IM, indicando que esses MVs podem ser úteis no diagnóstico de IM. No entanto, o resultado para MVLs foi negativo.

Microvesículas (MVS) ou micropartículas (MPS) têm relação não só com processos inflamatórios e trombóticos, mas com tecido de processo regenerativo e angiogênese, o que pode ser uma função protetora. Além disso MVS podem ser um sinalizador de estímulo celular da homeostase e apoptose. Pacientes diabéticos têm aumento da liberação de MVS e isso pode ser um biomarcador da progressão diabética por retinopatia. A abordagem farmacológica é útil devido à disfunção endotelial. O bloqueador do sistema angiotensina-retiniana e o bloqueador dos canais de cálcio podem ser boas opções no diabetes mellitus tipo 2.21 Pinheiro et al.22 avaliaram o efeito do fármaco antiplaquetário clopidogrel associado ou não à rosuvastatina (40 mg) nos níveis de MPE e MPP em pacientes com doença coronária estável em estatinas durante pelo menos três meses. Esses autores identificaram um aumento nos níveis de MPP após suspensão da rosuvastatina e manutenção de apenas clopidogrel por quatro semanas e uma tendência para maior liberação de MPE nesses pacientes. Eles sugeriram que ocorreu um aumento na apoptose das plaquetas e que a rosuvastatina pode ter um efeito protetor no endotélio quando associado ao clopidogrel.22 Em estudo semelhante, França et al.,23 avaliaram a influência da atorvastatina (80 mg) associada ou não ao clopidogrel em pacientes com doença coronária estável. Esses autores sugerem maior estabilidade vascular promovida pela atorvastatina após a identificação de uma relação inversa entre a concentração plasmática de atorvastatina e os níveis de MPP.23

MVs têm uma membrana fosfolipídica bicamada.24 A presença de PS externalizada nas superfícies das MVs indica um perfil de distribuição de fosfolípidos alterado em comparação com a membrana plasmática de uma célula de mamífero em repouso. Além disso, as moléculas presentes na superfície externa, uma vez definidas, fornecem marcadores acessíveis para a detecção e caracterização de MVs usando sondas moleculares.25 As MVA expressam fosfatidilserina (PS) na sua superfície e são atualmente definidas como MVs apoptóticas. É mostrado que os níveis de AMVs foram significativamente mais elevados em pacientes com IM do que nos controles saudáveis. Isso é assim provavelmente devido à isquemia miocárdica e hipóxia que geram apoptose celular, liberando assim grandes quantidades de MVAs. Em cada caso, a variação nos níveis de MVAs mostra que ocorre apoptose celular. Um estudo in vitro descobriu que MVs extraídas do sangue circulante de um paciente com infarto do miocárdio e aplicadas aos anéis aórticos isolados de um rato, levaram a danos severos da função endotelial.26 Assim, o alto nível de MVAs e seu efeito pode ser a causa da progressão do infarto do miocárdio.

As MVPs são definidas como vesículas membranosas derivadas das plaquetas que são definidas e identificadas pelas moléculas de superfície CD62P e CD63.27 Com a capacidade de se ligar aos fatores de coagulação VIII, Va e IX, as MVPs não apenas refletem a ativação das plaquetas como também contribuem para a ativação da via de coagulação e da trombogénese.28,29 Verificou-se que existia um alto nível de MVPs no sangue periférico dos pacientes com IM. A causa principal pode ser a mudança da força de cisalhamento do fluxo sanguíneo induzida por alterações patológicas nos vasos sanguíneos dos pacientes com IM. Estas alterações promovem a agregação e ativação das plaquetas, conduzindo assim à geração de um grande número de MVPs. Isto sugere que o aumento de MVPs pode ser ainda mais expandido pela reação de coagulação dos vasos sanguíneos nos pacientes com IM.

A disfunção das células endoteliais desempenha um papel importante no IM. MVEs são vesículas da membrana subcelular liberadas da célula endotelial durante a ativação ou apoptose.30 As MVEs carregam marcadores específicos que se originam das células maternas, incluindo CD31, CD51, CD54, CD62E, CD105, CD144 ou CD146. Verificou-se que as MVEs foram significativamente mais elevadas no grupo IM. Isso pode ser devido à disfunção das células endoteliais, que liberam abundantes MVEs no sangue. Quando as MVEs foram incubadas com células endoteliais de veias umbilicais humanas (HUVECs), a proliferação de células endoteliais diminuiu e sua apoptose aumentou, então a capacidade de angiogênese caiu drasticamente.31 O alto nível de MVEs é considerado como uma causa da piora da condição induzindo disfunção endotelial nos estados de IM.

Ao contrário da única fonte de MVEs ou MVPs, as MVLs podem se originar de neutrófilos, monócitos/macrófagos e linfócitos.32 Elas também expressam marcadores de suas células parentais. Foram utilizados vários anticorpos para capturar MVLs, incluindo CD4, CD14, CD11a, etc. Combinada com os resultados clínicos, esta meta-análise constatou que não houve variação significativa no nível de MVLs entre os controles de saúde e pacientes com IM. Mas os estudos que usaram anticorpos CD4 e CD14, mostraram que o nível de MVLs foi maior em pacientes com IM. Quando o anticorpo CD11a foi usado, foi encontrada uma confusão de resultados contraditórios. Portanto, estudos adicionais são necessários para investigar mais o nível de MVLs em IM. Entretanto, a medição de MVLs, devido à sua falta de padronização, ainda requer técnicas elaboradas.

Limitações desta meta-análise devem ser consideradas. Em primeiro lugar, a qualidade dos estudos individuais nem sempre foi óptima, como é demonstrado pela falta geral de informação sobre alguns estudos. Assim, utilizamos desigualdades simples e elementares para estimar a média e a variância desses estudos. Mas não é exatamente o suficiente. Em segundo lugar, há heterogeneidade de DMP entre os estudos, correspondendo em parte à heterogeneidade nas definições do estudo. Em terceiro lugar, embora a qualidade dos estudos incluídos tenha sido considerada globalmente adequada, os resultados do presente estudo precisam ser interpretados com cautela, uma vez que nem todos os estudos relataram potenciais variáveis de confusão e seu ajuste nas análises. Finalmente, os dados meta-analíticos também precisam ser cautelosamente interpretados, dada a heterogeneidade substancial entre os estudos.

 Conclusão

Esta meta-análise mostrou que níveis mais elevados de MVAs, MVPs e MVEs no sangue periférico podem estar associados a pacientes com IM, indicando que essas MVs podem ser úteis no diagnóstico de IM. No entanto, o resultado de MVLs foi negativo.

Fontes de financiamento

O presente estudo foi financiado pelo National Natural Science Foundation of China through grant n°. 81602496; Science and Technology Foundation of Administration of Traditional Chinese Medicine of Tianjin, China, nos 2015022 and 13047; Science and Technology Foundation of Tianjin Municipal Commission of Health and Family planning, n°. 2013KZ054.

Vinculação acadêmica

Não há vinculação deste estudo a programas de pós-graduação.