Tag: malaria

Plasmodium vivax infects hepatocytes to form schizonts that cause blood infection, or dormant hypnozoites that can persist for months in the liver before leading to relapsing blood infections. The molecular processes that drive P. vivax schizont and hypnozoite survival remain largely unknown, but they likely involve a rich network of host-pathogen interactions, including those occurring at the host-parasite interface, the parasitophorous vacuole membrane (PVM). Using a recently developed P. vivax liver-stage model system we demonstrate that host aquaporin-3 (AQP3) localizes to the PVM of schizonts and hypnozoites within 5 days after invasion. This recruitment is also observed in P. vivax-infected reticulocytes. Chemical treatment with the AQP3 inhibitor auphen reduces P. vivax liver hypnozoite and schizont burden, and inhibits P. vivax asexual blood-stage growth. These findings reveal a role for AQP3 in P. vivax liver and blood stages and suggest that the protein may be targeted for therapeutic treatment.

Dora Posfai, Steven P. Maher, Camille Roesch, Amélie Vantaux, Kayla Sylvester, Julie Péneau, Jean Popovici, Dennis E. Kyle, Benoît Witkowski, Emily R. Derbyshire. Cell Chem Biol. 2020 Mar 24. pii: S2451-9456(20)30083-0. doi: 10.1016/j.chembiol.2020.03.009.

Advanced cell culture methods for modeling organ-level structure have been demonstrated to replicate in vivo conditions more accurately than traditional in vitro cell culture. Given that the liver is particularly important to human health, several advanced culture methods have been developed to experiment with liver disease states, including infection with Plasmodium parasites, the causative agent of malaria. These models have demonstrated that intrahepatic parasites require functionally stable hepatocytes to thrive and robust characterization of the parasite populations’ response to investigational therapies is dependent on high-content and high-resolution imaging (HC/RI). We previously reported abiotic confinement extends the functional longevity of primary hepatocytes in a microfluidic platform and set out to instill confinement in a microtiter plate platform while maintaining optical accessibility for HC/RI; with an end-goal of producing an improved P. vivax liver stage culture model. We developed a novel fabrication process in which a PDMS soft mold embosses hepatocyte-confining microfeatures into polystyrene, resulting in microfeature-based hepatocyte confinement (μHEP) slides and plates. Our process was optimized to form both microfeatures and culture wells in a single embossing step, resulting in a 100 μm-thick bottom ideal for HC/RI, and was found inexpensively amendable to microfeature design changes. Microfeatures improved intrahepatic parasite infection rates and μHEP systems were used to reconfirm the activity of reference antimalarials in phenotypic dose-response assays. RNAseq of hepatocytes in μHEP systems demonstrated microfeatures sustain hepatic differentiation and function, suggesting broader utility for preclinical hepatic assays; while our tailorable embossing process could be repurposed for developing additional organ models.

Steven P. Maher, Amy J. Conway, Alison Roth, Swamy R. Adapa, Phillip Cualing, Chiara Andolina, James Hsiao, Jessica Turgeon, Victor Chaumeau, Myles Johnson, Chris Palmiotti, Naresh Singh, Samantha J. Barnes, Raahil Patel, Virginia Van Grod, Robert Carter, H.-C. Steve Sun, Jetsumon Sattabongkot, Brice Campo, François Nosten, Wajeeh M. Saadi, John H. Adams, Rays H. Y. Jiang, and Dennis E. Kyle. Lab Chip. 2020 Feb 14. doi: 10.1039/c9lc00921c

We have demonstrated previously that amino-artemisinins including artemiside and artemisone in which an amino group replaces the oxygen-bearing substituents attached to C-10 of the current clinical artemisinin derivatives dihydroartemisinin (DHA), artemether and artesunate, display potent activities in vitro against the asexual blood stages of Plasmodium falciparum (Pf). In particular, the compounds are active against late blood stage Pf gametocytes, and are strongly synergistic in combination with the redox active drug methylene blue. In order to fortify the eventual selection of optimum amino-artemisinins for development into new triple combination therapies also active against artemisinin-resistant Pf mutants, we have prepared new amino-artemisinins based on the easily accessible and inexpensive DHA-piperazine. The latter was converted into alkyl- and aryl sulfonamides, ureas and amides. These derivatives were screened together with the comparator drugs DHA and the hitherto most active amino-artemisinins artemiside and artemisone against asexual and sexual blood stages of Pf and liver stage P. berghei (Pb) sporozoites. Several of the new amino-artemisinins bearing aryl-urea and -amide groups are potently active against both asexual, and late blood stage gametocytes (IC₅₀ 0.4-1.0 nM). Although the activities are superior to those of artemiside (IC₅₀ 1.5 nM) and artemisone (IC₅₀ 42.4 nM), the latter are more active against the liver stage Pb sporozoites (IC₅₀ artemisone 28 nM). In addition, early results indicate these compounds tend not to display reduced susceptibility against parasites bearing the Pf Kelch 13 propeller domain C580Y mutation characteristic of artemisinin-resistant Pf. Thus, the advent of the amino-artemisinins including artemiside and artemisone will enable the development of new combination therapies that by virtue of the amino-artemisinin component itself will possess intrinsic transmission-blocking capabilities and may be effective against artemisinin resistant falciparum malaria.

Ho Ning Wong, Vivian Padín-Irizarry, Mariëtte E. van der Watt, Janette Reader, Wilna Liebenberg, Lubbe Wiesner, Peter Smith, Korina Eribez, Elizabeth A. Winzeler, Dennis E. Kyle, Lyn-Marie Birkholtz, Dina Coertzen, and Richard K. Haynes. Front Chem. 2020 Jan 10;7:901. doi: 10.3389/fchem.2019.00901. eCollection 2019.