Caspase-1 As a Therapeutic Target in Intravascular Hemolysis-Induced Microvascular Inflammation and Occlusive Processes

Hemolytic anemias, such as sickle cell disease (SCD), are a group of acute and acquired conditions characterized by the accelerated destruction of red blood cells (RBC). Intravascular hemolysis (IVH), or RBC lysis within the bloodstream, incurs the release of damage-associated molecular patterns (DAMPs), trigging cell activation and immune responses. Caspase-1 (Casp-1), a protease enzyme, plays a critical role during inflammatory processes by initiating programed cell death and promoting the cleavage of pro-interleukin (IL)-1β into its active form, IL-1β, through inflammasome assembly. Here, we aimed to elucidate the complex mechanisms involved in IVH-induced inflammation, leukocyte-endothelium interactions, and microvascular dynamics. Acute IVH was induced in C57BL/6 mice (HEM) by the injection of sterile water (i.v., 150 µl), and control mice received i.v. saline (CON) (n=3-8 per group). Intravital microscopy was performed at 15 min post IVH induction on the cremaster muscle of mice to quantify venular leukocyte (WBC) rolling and adhesion, and non-invasive laser Doppler flowmetry (LDF) measured blood perfusion in the murine pelvis microvasculature. Blood samples were collected at 1-hour post-IVH for ELISA and flow cytometry analyses. Immortalized human endothelial cells (HUVEC; n=7 per group) were stimulated with heme or S100A8 for 3 hours. HEM mice demonstrated significantly increased plasma heme (P