Inhibition of phosphoinositide 3-kinase-y improves liver function in sepsis by preventing RhoA-mediated cholestasis

in: Infection (2019)
Martinac, Petra; Press, Adrian T.; Medyukhina, Anna; Shi, Juanzi; Täuber, Daniela; Hoeppener, Stephanie; Cseresnyes, Zoltan; Scheblykin, Ivan G.; Gräler, Markus H.; Rubio, Ignacio; Figge, Marc Thilo; Schubert, Ulrich S.; Bauer, Michael; Benecke, Kay-Jovanna
Introduction: Liver has been increasingly considered as a target and modulator of manifold infectious diseases, making it a key object for disease progression and prognosis. Excretory dysfunction of the liver is an early and frequent event in polymicrobial sepsis and is strongly associated with the survival of the host. Different pathogen-associated molecular patterns (cytokines, chemokines) and inflammatory cells affect hepatic integrity. PI3K-c is a promising target of membrane shaping processes, cytoskeletal remodeling, cellular polarization, metabolism, and many other essential cellular developments. Furthermore, it is associated with many G protein-coupled receptors, such as chemokine receptors in vivo, playing an important role in several immune processes. In hepatocytes, PI3K-c regulates the phase I and phase II biotransformation and the elimination of bile acids by affecting the activity of ATP-dependent canaliculi transporters. The latter regulates intracellular trafficking towards the membrane, significantly affecting the liver function. The activating interactions between small GTPases and PI3K isoforms are manifold, directly and indirectly mediating migration, cell growth, and survival. Objectives: The present study investigates for the first time the impact of the inhibition of PI3K-c via a RhoA pathway to prevent dysfunction. Methods: In accordance with Thuringian animal welfare association guidelines, sepsis was induced by applying the model of peritoneal contamination and infection (PCI) while sham animals were injected intraperitoneally with sterile saline. All animals had supportive therapy. Different treatment regimens of AS605240 and respective vehicle groups were applied during the first 5 days of the infection, the phase in which liver failure determines the outcome. The underlying PI3K-c/RhoA molecular mechanism was tested in HepaRG cells, primary murine hepatocytes, and the liver tissue. Results: The levels of cytokines and of bile acid conjugation revealed a conjugation inability and an increase in proinflammatory cytokines in PCI vehicle groups in comparison to AS605240 treated animals. RhoA activation was observed in CM-treated HepaRG cells, as well as in the PCI sepsis model in primary murine hepatocytes, both being resolved by pharmacological PI3K-c inhibition. The amount and aggregation of b-actin was elevated in the PCI groups while fluorescently stained MRP2 was retrieved to the membrane aftertreatment with AS605240 inhibitor indicating that PI3K-c inhibition attenuates RhoA activation, both in vitro and in vivo. Conclusions: The results demonstrate a direct link between PI3K-c activity and selective RhoA activation leading to an aggregation of F-actin in hepatocytes. The pharmacological inhibition of PI3K-c by AS605240 interferes with the sepsis-induced RhoA activation and the subsequent development of cholestasis in vitro and in vivo, respectively.

DOI: Array

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