Emerging pathways in thromboinflammation of sickle cell disease: novel findings in disease pathogenesis

Sickle cell disease (SCD) is increasingly recognized as a chronic thromboinflammatory disorder, marked by persistent intravascular hemolysis, sustained endothelial activation, and multicellular aggregate formation. Free hemoglobin and heme act as damage-associated molecular patterns, activating Toll-like receptor 4 and promoting inflammatory and procoagulant responses in endothelial cells, monocytes, and neutrophils. Hyperreactive platelets, sickled red blood cells, and activated leukocytes interact with the endothelium to propagate vascular occlusion and thrombin generation. This persistent thromboinflammatory state targets low-flow microvascular beds in the bone marrow, lung, kidney, spleen, and brain, culminating in progressive end-organ dysfunction. In this article, we review the cellular and molecular drivers of thromboinflammation in SCD, highlighting how sustained vascular injury leads to deep vein thrombosis, stroke, nephropathy, and cardiopulmonary complications. Understanding these mechanisms is essential for developing targeted strategies to disrupt the thromboinflammatory cycle and prevent irreversible organ damage in SCD.