Abstract 457: Outer Membrane Vesicle From Pseudomonas Aeruginosa Causes Inflammation and Cardiac Dysfunction

Abstract

Rationale: P. aeruginosa ( P.a ) infection causes severe pneumonia in ICU patients that lead to cardiac inflammation, eventual tissue remodeling, fibrosis, and cardiac complication. Growing evidence indicates that cardiac resident CCR2 - , MHC-II low macrophages function as important regulators of cardiac inflammation and steady-state heart function. After tissue injury or infection, inflammatory monocytes are recruited to the heart and differentiate into inflammatory macrophages, which contribute to cardiac inflammation and dysfunction. Our preliminary result showed P.a. infection causes cardiac inflammation, fibrosis, and cardiac dysfunction without disseminating into the heart tissue. Also, the gram-negative bacteria can release toxins or outer membrane vesicles (OMVs) that target host cells and induces apoptosis. Thus we hypothesize that the cardiac damage caused by P.a infection is mainly due to the release of bacterial toxins and OMVs or inflammatory mediators released by immune cells. Understanding the molecular mechanism of cardiac inflammation and dysfunction is critical for the development of host-directed therapy. Objective: To identify the mechanism of P.a induced inflammation and cardiac dysfunction to develop therapies to prevent cardiac damage during infection. Methods and Results: To investigate the role of OMVs in cardiac inflammation and cardiac dysfunction, we have isolated OMVs from P. aeruginosa culture supernatant and purified using ultracentrifugation followed by gradient centrifugation. We quantified OMVs and used to stimulate the MDMs, BMDMs and hiPSC cardiomyocytes. Our in vitro study showed that OMVs activates Akt and MAPK signaling pathways and induces the production of inflammatory cytokines from macrophages. Additionally, we found that OMVs incubation significantly reduced the hiPSC myocyte contraction. Conclusion: These studies demonstrated that OMVs from P.a induced inflammatory cytokine production and subsequent myocyte contractile dysfunction. Studies are ongoing to determine the role of OMVs on the action potential of hiPSC-CMs. In future, we will determine the impact of OMVs in cardiac dysfunction in mouse model.