Inhibition of Wnt signaling in primary human hepatocytes promotes Plasmodium falciparum liver stage development

After infection of the human host, the first stage of the Plasmodium falciparum (Pf) lifecycle takes place in the liver. However, understanding of host-parasite interactions in this stage has been limited by the rapid loss of functionality in cultured primary human hepatocytes (PHHs), the natural host source for Pf liver stage parasites. Here, we link loss of hepatic functionality to a drastic loss in Pf permissiveness, which we can effectively prevent by using a novel medium containing serum-replacement and signal transduction inhibitors. Integrating transcriptomic analysis and phenotypic assessment of infection outcome, we identified several host signaling pathways that influence Pf liver stage development via modulating the host cell environment. Inhibition of the Wnt pathway in particular has a major impact on the size and maturity of Pf liver stage schizonts, by retaining the metabolic activity and epithelial nature of PHHs. Understanding how alteration of the host cellular state via signalling pathways determine Pf liver stage permissiveness provides insight into host-parasite interactions and may accelerate development of novel therapeutic strategies via improved in vitro liver stage models. Overall design: In vitro cultured primary human hepatocytes (either uninfected and infected with NF135/NF54 strain of Plasmodium falciparum) were kept under mock/IWP2/5C treatment till harvest at day 5 post-infection cognate timepoints. All samples, including freshly isolated hepatocytes, were preserved in TRIzol reagent for RNA isolation. Total RNA was isolated using the Zymo Research RNA extraction kit. Stranded mRNA sequencing library was prepared with the Kapa mRNA HyperPrep Kit. 36bp paired-ended sequencing was performed on the Illumina NextSeq 550 platform. Differential gene expression analysis was performed between freshly isolated and mock vs IWP2 treated hepatocytes.