Sickle cell disease (SCD) is a condition characterized by chronic inflammation and increased thrombotic risk in both arterial and venous beds. In the last decades, important advances were achieved in understanding the pathophysiology of hypercoagulability in these patients. However, several new mediators of coagulation activation have been recently described in other pathological contexts, opening new avenues for the research about hypercoagulability in SCD. Among these new mediators, Neutrophil Extracellular Traps (NETs) and free heme can be considered the most promising targets. In this project, we aim to use different experimental strategies to explore the role of these elements in the pathophysiology of SCD. The role of NETs will be explored by specific assays of NETosis, and by the evaluation of the expression of a key regulatory checkpoint of NET formation, which is the protein PAD4 in patients with SCD. These results will also be correlated with classic biomarkers of coagulation activation to question the association of these two processes. We will also use an in vitro model of NET formation induced by free heme (one of the pivotal factors of hypercoagulability in SCD), to evaluate: (i) the participation of PAD4 in heme-induced NETosis, (ii) the effect of PAD4 inhibitors in this process, and (iii) the profile of post-transcriptional modification of histones (a key step of NET formation) induced by heme. As a second strategy, we will validate the results of a recently published meta-analysis of gene expression studies involving heme-stimulated endothelial cells and patients with SCD performed by our group, in which we identified two candidate genes (IFI27 and SYK) associated with innate immunity activation. The project is part of a broader effort, started a few years ago in the Hematology and Hemotherapy Center of Unicamp, which aim to evaluate the pro-thrombotic mechanisms of SCD and the pathways activated by the free heme in this process.
News published in Agência FAPESP Newsletter about the scholarship: