Correlations Between Level Of Serum CRP And Circulating Endothelial Progenitor Cells With Carotid Plaque Calcification

Background and ObjectiveCarotid artery atherosclerosis participates in ischemic stroke or transient ischemic attack,and one possible reason is that the ruptured unstable plaque resulted in the local thrombosis or micro-embolus thus leading to the ischemic event.Chronic inflammation promotes the genesis and progress of carotid atherosclerosis.The serum CRP is believed as a key factor in carotid atherosclerosis and is closely related with ischemic stroke.Circulating endothelial progenitor cells are mainly generated from bone marrow when it occurs to ischemic stimulation and can participate in neovascularization and maintain the integrity of the endothelium.In recent decades,EPC is believed as a new factor in maintaining the endothelium integrity.Besides,EPC is related with burden of the atherosclerosis and recognized as one of the risk predictive factor in cardiovascular and cerebrovascular disease.Calcification is marker of atherosclerosis progress and also recognized as risk predictive factor in myocardial infarction and ischemic stroke.Calcification is also one of morphology and construction component.Recent studies about influence of plaque calcification on plaque stability and relationship between clinical ischemic event and calcification are the hot foci.With the continuously update in radiological technology,CT takes advantage in calcified plaque estimation.However,studies concerning correlations between levels of serum CRP and circulating EPCs with plaque calcification are less,of which few studies find that level of serum CRP is independent correlated with coronary calcification.As is known for all,the levels of biomarker are susceptible for fluctuation in the acute phase of ischemic event,which will disturb the analysis between the above factors.Therefore,we explored the correlation between level of serum CRP and circulating EPCs with carotid plaque calcification in ischemic stroke or TIA patients whose onset time is betweenl to 6 months from the event.MethodsWe prospectively included patients with documented non-cardiac ischemic stroke or TIA in anterior circulation in neurology department of Jinling Hospital.The inclusion criterion:the onset time is between 1 to 6 months,age>=18 years.Exclusion criterion:carotid non-atherosclerotic stenosis,extracranial carotid stent or CEA,symptomatic coronary or peripheral artery disease,severe liver or kidney disease,hyperthyroidism or hyperparathyroidism,malignancy,metabolic disorders,recent infection and fever,chronic inflammation,autoimmune disease,recent bone fracture history,bisphosphonates intake history.CT scan used the 64-slice double source CT made in Siemens.According to CT value for the carotid plaque,we classified the subjects as non-calcification group and calcification group.Also,we used the post-processing software within the machine for calcification extent estimation using Agatston method.We collected the demographic and clinical data of all the participants.Serum CRP levels were also measured using immunoturbidimetry and the normal value is 0-8mg/L.We also used the flow cytometry made in BD company for multicolor analysis.We defined CD45dim/-CD34C+D309+cells as EPCs.Totally,5-6×105 cells were collected,and the whole number of EPCs was calculated as percent in the lymphocyte gate.For statistics,Independent sample t test,Mann-Whitney test and Pearson ?2 test or Fishexact were used appropriately.The multivariate binary logistic regression analysis was used to analyze the correlation between level of serum CRP and EPCs and percent of carotid artery moderate-severe stenosis with carotid plaque calcification.Spearman rank correlation test was used to analyze the correlation between age?level of serum CRP and EPCs with carotid plaque total calcium score.Two-tailed p<0.05 was thought as statistics difference.ResultsFinally,165 patients were included in our study.The average age of all the participants were 62.4±10.6 years,male patients accounted for 67%totally.113 patients were in the calcification group,52 patients were included in non-calcification group.The median age in the calcification group is[66(58-73)years],higher than that in the non-calcification group[58(51-66)years],P<0.05.The median level of serum CRP in calcification group is[1.9(0.5-3.8)mg/L],higher than that in the non-calcification group[0.0(0.0-2.2)mg/L],P<0.05.The percent of moderate-severe stenosis in calcification patients accounted for 32%,markedly greater than that in the non-calcification group(6%),p<0.05.Other factors have no difference between the two groups,P?0.05.In the multivariate binary logistic regression analysis,age(OR:1.053,95%CI:1.013-1.095,P=0.010)and level of CRP(OR:1.212,95%CI:1.033-1.423,P=0.018)and percent of moderate-severe stenosis(OR:9.909,95%CI:2.204-44.556,P=0.003)still show statistic significance after adjusting for level fast blood glucose and history of hypertension.Spearman rank correlation test found that age(r=0.325,p=0.000)and level of serum CRP(r=0.372,p=0.000)were both correlated with carotid plaque calcium score.Meanwhile,we collected flow cytometric data of EPCs from 99 participants in later period.And finally 84 participants were analyzed.Unexpected,we did not found any significant difference in EPCs number between calcification group[0.153%,(0.068%-0.396%)]and non-calcification group[0.126%,(0.055%-0.254%)],p=0.335.Spearman rank correlation test also found no relationship between EPCs number and carotid plaque calcium score(r=0.018,p=0.870).ConclusionIn this study,we found that age,level of serum CRP,and moderate-severe carotid artery stenosis were independent risk factors of carotid plaque calcification in patients with stable ischemic stroke or TIA.Unfortunately,we found no correlation between level of circulating EPCs and carotid plaque calcification.Future large sample studies concerning this issue are extremely needed.