HM02 - Plasma plasminogen activator inhibitor (PAI-1) activity in dogs with immune-mediated hemolytic anemia

Abstract:

Background: Immune-mediated hemolytic anemia (IMHA) results in high mortality rates due to fatal thromboemboli. Increased plasminogen activator inhibitor (PAI-1) gene expression has been reported in IMHA dogs, indicating that hypofibrinolysis may contribute to thrombotic risk. Plasma PAI-1 activity in dogs with IMHA is unknown.

Objectives: Develop and validate a PAI-1 kinetic activity assay by modifying a human fluorimetric tissue plasminogen activator (tPA) activity assay and measure plasma PAI-1 activity in dogs with IMHA and healthy controls (HC). Animals: 16 dogs with non-associative IMHA; 11 HC dogs

Methods: Prospective cross-sectional study. The PAI-1 activity assay was configured as a human tPA activity assay modified by the addition of recombinant canine PAI-1 to generate a PAI-1 standard curve. Repeatability, reproducibility, recovery, and limits of blank (LoB) and of detection (LoD) were determined according to quality assessment guidelines of the American Society for Veterinary Clinical Pathology. Mann-Whitney U tests compared median plasma PAI-1 activity between groups.

Results: Assay performance was acceptable including repeatability of 15.8%, reproducibility of 7.9% and observed to expected recovery ratios of 86-120% for all tested concentrations. LoB and LoD were 10 and 15 ng/ml. Plasma PAI-1 activity was significantly higher in IMHA (median [range]: 48 [15-439] ng/ml) compared to HC (15 [15-15] ng/ml) dogs (P < .001). Conclusions and Clinical Importance: An analytically validated PAI-1 activity assay detected increased plasma PAI-1 activity in dogs with IMHA compared to HCs. PAI-1 inhibitors could be novel therapeutics to prevent fatal thrombotic events in IMHA patients.