Cell death in lung transplantation. The roles of apoptosis, necroptois, and pyroptosis

Abstract

Abstract Objective For patients with end stage lung disease, lung transplantation (Ltx) is the unique treatment option. Nevertheless, a large number of lung allografts fail, because of acute or chronic rejection. Innate immune responses following Ltx play a critical role in the development of primary graft dysfunction, and ultimately promote the development of chronic lung allograft dysfunction, leading to increased mortality after lung transplantation. Here, we focus on the mechanisms responsible for disruption of the cells membranes integrity, resulting in the release of Damage Associated Molecular Patterns (DAMPs) and activation of cell death pathways triggering cell injury in lungs with different preservation status. Methods Rat lungs were exposed to cold ischemia (CI group, n=9) or warm ischemia (WI group, n=9). In CI group, after Perfadex flushing, and hypothermic preservation (4 h) left lung was transplanted. In WI group, after 1 h of in situ WI, flashing and 3 h cold preservation the left lung was transplanted. Lung mechanics were determined during reperfusion. Recipients were sacrificed at 30, 60 and 120 min after Ltx. Bronchoalveolar lavage (BAL) was performed on the grafts to measure markers of cellular injury, and cytokines. Cell death markers were determined in graft tissue. Biological samples were kept at -80°C for additional analysis. Results Compared to CI, WI group displayed significantly decreased graft function associated with increased activation of pyroptotic cell death (NLRP3, caspase1, IL-1β) pathway, whereas apoptotic (caspas3 and caspase7) and necroptotic (RIP1, RIP3, MLKL) cell death pathways activation were similar in both groups. WI group showed more important cellular damage with DAMPs release (LDH, sRAGE, HMGB) and inflammation (CXCL1, IL1-β, IL-33). Conclusion Our results suggest that pyroptosis could play a critical role in the development of early graft dysfunction in lungs subjected to warm ischemia. Inhibition of pyroptotic pathway could be a strategy to improve damaged donor lungs.