Silent cerebral infarctions (SCI) occur in 22% of children with sickle cell disease (SCO), are associatedwith decreased cognitive function and are a significant risk factor for the development of stroke. Bydefinition, these children have MRI and pathologic evidence consistent with cerebral infarction, without overtsymptoms of stroke. As the etiology of SCI is unknown, we lack the means to easily identify children withSCI or at risk for SCI to guide early intervention or follow the success of therapy. The overall goal of thisgrant proposal is to identify diagnostic/etiologic plasma biomarkers of SCI in children with SCO. In our pilotstudies, using a non-biased proteomic analysis of plasma samples from patients with or without SCI in theSIT Trial, we have found significant differences in the plasma protein profile of children with SCI and haveidentified two circulating brain specific proteins, neural cell adhesion molecule 1 and glial fibrillary acidicprotein, a known biomarker of stroke. Based upon these studies, we propose to identify the plasmabiomarkers of SCI, establish whether circulating biomarker proteins can predict SCI and probe deep in theplasma proteome of children with SCI to identify diagnostic biomarkers validated to the brain andvasculature. The significance of the proposed studies is that identification of circulating markers of SCIwould allow early intervention in these children and provide insight into the design of new therapies. This isparticularly important, as our present therapy of repeat transfusions carries a high morbidity in and of itself.Therefore, we hypothesize that plasma samples from children with SCO and SCI will containdiagnostic/etiologic biomarkers of SCI. To examine this hypothesis, our proposal draws on the uniqueresources of the large and highly phenotyped plasma samples in the SIT Trial Biologic Respository and theNHLBI Cardiovascular Proteomics Center at Johns Hopkins. In three aims we will: first, using state of the artnon-biased proteomic techniques (HPLC. ITRAQ and LC/MS/MS), identify plasma diagnostic biomarkers ofSCI; second, validate our biomarkers using a combination of western blotting and high throughput multiplexantibody arrays against the SIT Trial plasma repository to test the efficacy of the biomarkers in predictingSCI; and third, go back to the brain, to localize biomarker proteins to the brain and test their specificity forSCO and ischemic neurologic injury.These studies describe the discovery and validation phases of work to uncover diagnostic/etiologicplasma biomarkers of SCI in children with SCO. It is also possible that these studies may provide newinsights into the development of stroke in SCO and stroke in general.
Showing the most recent 10 out of 31 publications
