A18652 Kallikrein-1 Overexpression Alleviates Age-associated Cardiac Fibrosis Through Alternatively Regulating Activated Macrophage Polarization

Objectives: The study was designed to determine the effect of KLK1 on cardiac aging and the mechanism of macrophage polarization in cardiac fibrosis Methods: Experiments are carried out using 3 and 24-month-old SD and hKLK1 overexpression rats. Echocardiography were performed to determine the cardiac function. Morphological staining were used to evaluate cardiac fibrosis and electron microscope to detect mitochondria ultrastructure. The speciemen were also used to detect expression of NAPDH subunits, anti-oxidative stress enzymes and ROS level by DHE staining. Immunofluorescence co-localization of CD68 and CD163, Th1 and Th2 cytokines examinations were used to measure macrophage polarization level. In the in vitro study migration capacity of Raw264.7 was detected by different dose of H2O2 administration with or without bradykinin or HOE-140 pre-treatment. Flow cytometry was used to examine the differentiation capacity of M0 towards M2 macrophage under the induction of H2O2 before IL-4 induction Results: hKLK1 overexpression protected against aging-induced cardiac hypertrophy and fibrosis, decreased expression of MCP-1, suppressed mitochondrial dysfunction and excess oxidative stress, decreased recruitment and retention of M2 macrophages and reduced secretion of pro-fibrotic cytokines mediated by TGF-β1/Smad3 signaling pathway. H2O2-induced senescence caused differentiation of RAW264.7 cells into M2-type cells and increased the secretion of Th2-type cytokines. In addition, bradykinin treatments reverse the enhanced migration capacity of Raw264.7induced by H2O2 treatments while HOE-140 administration recover the migration ability of macrophage. Conclusion: hKLK1 overexpression alleviated cardiac aging by alternatively regulating M2 recruitment and polarization mediated by p53-PGC-1α axis and TGF-β1/Smad3 pathway.