A Preliminary Study On The Mechanism Of Angiogenesis In The Occurrence Of Microhemorrhage And White Matter Lesions In Cerebrovascular Disease

Part 1.Angiogenesis and its influencing factors in patients with cerebral small vessel disease:A 68Ga-NOTA-PRGD2 PET/MRI multi-modality molecular imaging studyBackground and purpose:Cerebral small vessel disease(CSVD)is one of the important causes of ischemic stroke in the world.Whether there is hypoperfusion-induced angiogenesis in patients with CSVD remained uncertain.We aimed to investigate the angiogenesis and its influencing factors in patients with CSVD using integrin ?v?3-targeted PET/MRI multimodal molecular imaging and to detect serum levels of angiogenic factors.Methods:In this study,we recruited patients with CSVD between November 30,2016 and February 24,2018.Participants were included from Peking Union Medical College Hospital and underwent 68Ga-NOTA-PRGD2 PET/MRI.The maximum of standard uptake value(SUVmax)were detected in white matter hyperintensities(WMH),normal-appearing white matter(NAWM)and the WMH and NAWM junction area.The participants were divided into two groups based on 68Ga-NOTA-PRGD2 uptakes.Comparisons of voxel based cerebral blood flow(CBF)and grey matter volume were conducted within the groups.The Angiogenesis Array(Raybiotech,USA)and ELISA was used to determine the levels of angiogenic factors,inflammatory factors and S100B.Results:Of the 21 individuals,68Ga-NOTA-PRGD2 uptakes were significantly increased at the WMH and NAWM junction area.The patients with increased 68Ga-NOTA-PRGD2 uptake(SUVmax>0.17)were classified as group 2.The patients with SUVmax?0.17 were classified as group 1.The serum level of integrin ?V?3?VEGF-R2?IL-1? were significantly increased in group 2 compared to group 1(p=0.038,p=0.03,p=0.012).The WMH volume was an independent predictor of angiogenesis(OR 1.075,95%CI 1-1.154,p=0.049).Grey matter atrophy and reduced cerebral blood flow were found in group 2.Conclusions:Our study provides evidence that angiogenesis exists in CSVD.We found that angiogenesis was correlated with reduced CBF and high WMH burden.Further studies are warranted to verify angiogenesis as a molecular imaging marker and a novel therapeutic target for CSVD.Part 2.The role of angiogenesis in white matter hyperintensities penumbraBackground and purpose:The normal-appearing white matter(NAWM)surrounding white matter hyperintensities(WMH)with reduced cerebral blood flow(CBF)or white matter injury are considered as WMH penumbra,which may associate with WMH progression.It is unclear whether there is collateral revascularization in WMH penumbra.We aimed to determine whether angiogenesis exists in and has an impact on WMH penumbra and to evaluate factors affecting the presence of angiogenesis.Methods:In this study,twenty-one patients with confluent WMH of Fazekas grade 2 or higher on MRI were recruited between November 30,2016 and February 24,2018.Participants underwent 68Ga-NOTA-PRGD2 PET/MRI and were divided into two groups based on 68Ga-NOTA-PRGD2 uptakes.Seven NAWM layers were dilated away from the WMH by 2 mm each time.The structure WMH penumbras were analyzed using diffusion tensor imaging(DTI)-derived metrics,mean diffusivity(MD)and fractional anisotropy(FA).The CBF WMH penumbras were analyzed using CBF detected by arterial spin labeling(ASL).We compared 68Ga-NOTA-PRGD2 PET with standardized uptake value ratio(SUVr),CBF,FA and MD,in WMH and NAWM L1-L7.We fit linear mixed effects models with random effects for subject and fixed effects for layers.Results:The 68Ga-NOTA-PRGD2 uptakes were significantly increased at the WMH and NAWM junction area.For 14 patients with significant 68Ga-NOTA-PRGD2 uptake(group 2),SUVr was significantly higher in NAWM L1-L7 compared to WMH(p<0.001).In group 1,there was no significant difference between the layers(P=0.251).The structure penumbra defined by DTI-FA in group 2(8mm)was wider than group 1(2mm),the structure penumbra defined by DTI-MD was 10 mm,and the CBF penumbra defined by ASL-CBF was 12mm both in group 1 and group 2.There were negative correlations between CBF,FA and SUVr.Conclusions:Our study provides evidence that angiogenesis exists in WMH penumbra.We found that angiogenesis is correlated with reduced CBF and microstructure integrity.Further studies are warranted to verify angiogenesis as a predictive marker and a novel therapeutic target for the progression of WMH.Part 3.The role of angiogenesis in cerebral microbleedsBackground and purpose:The mechanism underlying the formation of cerebral microbleeds(CMBs)is not entirely clear.A relationship has been observed between angiogenic factors and the presence of CMBs.Integrin ?v?3 targeted positron emission tomography(PET)tracer 68Ga-NOTA-PRGD2 provide the novel possibility to image angiogenesis in vivo.We performed a study to explore the correlation between angiogenesis and CMBs and to study whether angiogenesis is associated with cerebral blood flow(CBF)and white matter integrity using 68Ga-NOTA-PRGD2 PET/MRI.Methods:Participants underwent 68Ga-NOTA-PRGD2 PET/MRI to detect the expression of integrin ?v?33 a biomarker of angiogenesis.Arterial spin labeling(ASL)and diffusion tensor imaging(DTI)were also performed.We compared 68Ga-NOTA-PRGD2 PET with standardized uptake value ratio(SUVr),CBF,and DTI metrics,including fractional anisotropy(FA)and mean diffusivity(MD),in CMBs regions and six concentric shells.We fit linear mixed effects models with fixed effects for distance of shells from the central CMBs and random effects for subject and for each CMB within subject.Results:Of the 18 individuals,68Ga-NOTA-PRGD2 uptakes were significantly increased at the sites of CMBs.Values of SUVr increased with increasing distance from the CMBs and appeared to have peaked at approximately 6-8 mm,accompanied by reduced CBF and white matter integrity.There was a positive correlation between SUVr and CBF,and a negative correlation between SUVr and FA.68Ga-NOTA-PRGD2 uptake was significantly higher in the group with high CMB burden(>10 CMBs)than in the group with low/moderate CMB burden(1-10 CMBs).The serum level of MMP-2 and integrin ?V?3 were significantly increased in the group with high CMB burden(>10 CMBs)compared to low/moderate CMB burden(1-10 CMBs).(p=0.001,p<0.001)Conclusions:This is the first noninvasive in vivo molecular imaging of angiogenesis in patients with CMBs.Our findings suggest that angiogenesis is associated with the presence of CMBs.We expect that this study will provide novel insights into the angiogenic factor integrin avP3 as a novel target for the monitoring and intervention of CMBs.Part 4.The association between large artery atherosclerosis and cerebral microbleeds:A systematic review and meta-analysis.Background and purpose:The aim of this systematic review and meta-analysis was to provide evidence that biomarkers of large artery atherosclerosis,including arterial stenosis and greater carotid intima-media thickness(cIMT),may serve as clinical markers of subclinical hemorrhage-prone cerebral small vessel disease,reflected by cerebral microbleeds(CMB s).Methods:We searched PubMed,MEDLINE,Embase,Web of Science,and the Cochrane Library to identify relevant studies published before July 1,2016.The association between arterial stenosis and CMBs was estimated by the odds ratio(OR)and 95%confidence interval(CI).The association of cIMT and CMBs was calculated using the standardized mean difference(SMD).Heterogeneity and publication bias were explored.Results:Eight studies including a total of 7,160 participants were pooled in meta-analysis.Six of the included studies were cross-sectional,except that 2 were prospective.We found a significant association between arterial stenosis>50%and the presence of CMBs(OR 1.95,95%CI:1.13-3.36,I2=56.1%).A fixed-effects model suggested that patients with CMBs were more likely to have a greater cIMT(SMD 0.20,95%CI:0.11-0.28,12=24.7%).Conclusions:This systematic review and meta-analysis found that there is a relationship between large artery atherosclerosis and CMBs.Future studies are needed to confirm the impact of atherosclerosis on the CMBs,which may have potential therapeutic implications.