Primary cilia as a targetable node between biliary injury, senescence and regeneration [RNA-seq]

Biliary complications are disabling conditions that arise in up to 25% of liver transplanted patients, resulting in additional surgical procedures, re-transplantation or, in the absence of a suitable regraft, death. Here, we investigate the role of the primary cilia, a highly-specialised sensory organelle, in biliary injury leading to biliary complications. Human biopsies were used to study the structure and function of primary cilia in liver transplant recipients that develop biliary complications (N=7), compared to successful transplants (N=12). To study the biological effects of the primary cilia during transplantation, we used murine models that recapitulate liver procurement and cold storage conditions, and the K19CreERT Kif3a flox/flox mouse model to conditionally eliminate primary cilia in cholangiocytes. Microarray and RNA-seq analysis were used to study these biological effects at the transcriptional level. To explore the molecular mechanisms responsible for the observed phenotypes, we used in vitro models of ischemia, cellular senescence and primary cilia ablation. Pharmacological and genetic approaches were used to target cellular senescence and the primary cilia, in mouse models and human donor livers. Prolonged ischemic periods pre-transplantation result in ciliary shortening and cellular senescence. Primary cilia damage results in biliary injury and a loss of regenerative potential. Initiation of senescence negatively primary cilia structure, establishing a negative feedback loop that further impairs regeneration. We conclude that primary cilia play an essential role in biliary regeneration; we demonstrate that senolytics and cilia-stabilising treatments provide a potential therapeutic opportunity to reduce the rate of biliary complications and improve the outcome of the liver transplanted patient.