336 Pharmacologic Modulation of Endothelial Cell Autophagy During Hypoxic Cold Storage and Reperfusion: Harnessing the Power of 'Self-Eating,' as a Pre-Treatment Strategy for Donor Organs

Abstract

OBJECTIVES/GOALS: Donor hearts are transported in cold storage (CS) and undergo ischemia-reperfusion injury (IRI) when transplanted. IRI injures microvascular endothelial cells (EC), heightens the immune response, and has been associated with increased autophagy. We aim to understand the changes in autophagy during CS and IRI and its impact on EC immunogenicity. METHODS/STUDY POPULATION: To study autophagy changes during IRI, immunoblotting for autophagy markers was performed in mouse cardiac ECs (MCECs) lysates. MCECs were in a cold preservation solution in a hypoxic chamber for 6 hours(h) and warm conditions with culture medium for 24 h. MCECs, under standard conditions, served as controls. Secreted interferon-gamma (IFN-γ) levels were quantified via ELISA to study autophagy and EC immunogenicity. MCEC-sensitized CD8+ T-cells were isolated from C57BL/6 spleens and co-cultured with MCECs pre-treated for 16 h with rapamycin or starvation, autophagy inducers, or chloroquine, an autophagy inhibitor under normal or IRI conditions. MCECs without any treatment served as controls. RESULTS/ANTICIPATED RESULTS: To determine autophagy levels in IRI, immunoblotting of MCEC lysates revealed a significant increase (P<0.01) in the established autophagy marker, LC3, at early time points post-reperfusion compared to NT conditions, indicating more autophagosome formation during CS and IRI. To assess the role of autophagy in EC immunogenicity, the co-culture experiment revealed that autophagy induction in MCECs under NT and HCS conditions with rapamycin had a 74.9-fold and 51.5-fold reduction of IFN-γ (pg/mL), resepectively, compared to the non-treated controls. In contrast, autophagy inhibition in MCECs with chloroquine resulted in 1.82-fold increase of IFN-γ compared to untreated controls. This suggests a protective role of autophagy in ECs during IRI. DISCUSSION/SIGNIFICANCE: We observed that autophagy may be protective during IRI by mitigating EC immunogenicity. Thus, pharmacologically modulating microvascular EC autophagy in donor hearts prior to transplantation may mitigate insults incurred during CS and IRI.