Delineating the role of autophagy in ischemia reperfusion injury
Final Report Abstract
In the clinical setting ischemia reperfusion injury (IRI) is an inevitable consequence of solid organ transplantation compromising the short and long term outcome of the graft and patient. Current strategies and treatment options are suboptimal and limited. We hypothesized that the induction of autophagy, a basal cellular recycling process, will limit ischemia reperfusion injury by decreasing reactive oxygen species, danger signal production and neutrophil recruitment during IRI. In an in vitro cell culture model of simulated ischemia reperfusion injury (sIRl) we demonstrated that autophagy can be manipulated during sIRI by pharmacologic treatment with rapamycin. This finding was associated with a reduction in reactive oxygen species production potentially by an increase of mitophagy. In cells treated with rapamycin and sIRl, a decrease in FUNDCl, a mitochondrial outer membrane protein with direct binding capacities to LC3, an autophagosome membrane protein, was detected. We hypothesize that rapamycin may promote an increase in FUNDCl triggered mitophagy. In addition, neutrophil adhesion may be attenuated by enhancing autophagy in the setting of IRl. Next, we employed an established in vivo murine model of IRl with partial clamping of the portal triad. Mice were treated with rapamycin to enhance autophagy and ATGI6L hypomorph mice with reduced expression of Atgl6L, a required membrane protein of autophagosomes, served as autophagy deficient controls. Using intravital microscopy we found no difference in the amount of Ly6/GR-I labeled neutrophil influx between groups at 2 hours post IRI, but aim to study different time points. However, there was a trend to increased protective IL-6 production in mice with enhanced autophagy. The data generated from this study suggest a beneficial effect from enhancing autophagy in the setting of IRJ. As autophagy can be manipulated using already established drugs like Rapamycin, Carbamazepin, or Lithium manipulating autophagy would provide a realistic and feasible option in diminishing IRI.
