Search

Introduction:The role of thrombin in acute myocardial infarction (AMI) has been well described, with recent attention having turned to its effect on NLRP3 inflammasome activation and the role that plays in the pathogenesis of AMI. Perfluorocarbon nanoparticles conjugated to phenylalanine-proline-arginine-chloromethylketone (PPACK NPs) are extremely potent local inhibitors of thrombin, but their role in therapy for AMI remains unclear. We hypothesize that pre-treatment with sustained locally acting PPACK NPs preserves cardiac function by attenuating thrombin-induced inflammatory processes, including those driven by the NLRP3 inflammasome.Methods:Nine mice underwent left anterior descending (LAD) occlusion for 45 minutes. At 30 minutes before LAD occlusion, mice were injected with PPACK (n=5) or control NPs (n=4). 24 hours post-reperfusion, hearts were excised and perfused. LAD was re-occluded and Lectin-488 perfused through the excised heart. Echo was performed pre- and post-reperfusion to assess cardiac function. Hearts were sectioned for follow up histological and protein analysis.Results:PPACK NP treated mice exhibited evidence of preserved cardiac function 24 hours post-reperfusion (Figure 1, A-B), reduced nuclear translocation of p65 in infarcted myocardium (Figure 1, C-D), and reduced inflammatory markers with better vessel preservation in the area adjacent to uninjured myocardium (Figure 1, E-F). The PPACK NP group also demonstrated suppression of NLRP3 inflammasome activation (Figure 2).Conclusion:Local inhibition of thrombin with anti-inflammatory PPACK NPs preserves cardiac function when administered systemically as pre-treatment.

Introduction:Acute kidney injury (AKI) confers a 25% chance of developing chronic kidney disease and a 50% increase in 10-year mortality risk. Clinical trials completed in 2018 indicated that targeting single pathological mechanisms of AKI failed to improve renal function and overall outcomes.Hypothesis:We hypothesized that local thrombin inhibition with sustained acting nanoparticle formulations would both protect renal vasculature and modulate inflammatory prostaglandins that drive the ischemia reperfusion injury (IRI) process even when administered after onset of injury.Methods:23 male C57Bl6 mice underwent bilateral warm IRI. Two hours after reperfusion, the mice were injected with either anti-thrombin (PPACK: phenylalanine-proline-arginine chloromethylketone) or control perfluorocarbon NPs. After 24 hours, kidneys were harvested for histological analyses and inflammatory prostaglandins by HPLC-MS, and blood for BUN.Results:PPACK NP treatment preserved renal vasculature (more purple CD31 stain in A vs B), reduced vascular inflammation (less VCAM-1 glomerular staining in C vs D), and preserved basement membrane and brush border components (intact peri-glomerular PAS staining in E vs F). Renal function was improved at 24 hours (G). PGD2 was reduced in both cortex and medulla (H and I).Conclusion:Targeting thrombin preserves renal vasculature and reduces inflammation, which improves renal function well after the onset of renal IRI induced AKI.Figure. Anti-thrombin nanoparticle treatment 2 hours after onset of AKI