Cell-derived microparticles and sickle cell disease chronic vasculopathy in sub-Saharan Africa: A multinational study

Although most individuals with sickle cell disease (SCD) live in sub-Saharan Africa, the natural history of the disease on this continent remains largely unknown. Intravascular haemolysis results in activation of circulating blood cells and release of microparticles (MPs) that exert pro-inflammatory effects and contribute to vascular damage. We designed a case-control study nested in the CADRE cohort (Coeur-Artère-DRÉpanocytose, clinical trials.gov identifier NCTO3114137) and based on extreme phenotypes, to analyse blood cell-derived MPs in 232 adult SS patients at steady state in Bamako and Dakar. Thirty-six healthy adult controls matched by age and sex were recruited in Bamako. The MPs concentrations were higher in SS patients compared to AA controls with a predominance of erythrocyte- and reticulocyte-derived MPs. These erythroid-derived MPs were significantly lower in patients with retinopathy (P = 0·022). Reticulocyte-derived MPs were significantly negatively and positively associated with a history of priapism (P = 0·020) and leg ulcers (P = 0·041) respectively. We describe for the first time the comparative patterns of plasma MPs in healthy subjects and patients with SCD living in sub-Saharan Africa and exhibiting various complications. Because our present results show no clear pattern of correlation between erythroid MPs and the classical hyper-haemolytic complications, we hypothesise a weak relevance of the hyper-haemolysis versus hyper-viscous paradigm in Africa.