P-Glycoprotein Inhibitors Differently Affect <i>Toxoplasma gondii</i>, <i>Neospora caninum</i> and <i>Besnoitia besnoiti</i> Proliferation in Bovine Primary Endothelial Cells

• Main Authors: Camilo Larrazabal, Liliana M. R. Silva, Learta Pervizaj-Oruqaj, Susanne Herold, Carlos Hermosilla, Anja Taubert
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Pathogens
• Subjects: P-glycoprotein; ABCB1-transporter; <i>Toxoplasma gondii</i>; <i>Neospora caninum</i>; <i>Besnoitia besnoiti</i>; verapamil
• Online Access: https://www.mdpi.com/2076-0817/10/4/395

Apicomplexan parasites are obligatory intracellular protozoa. In the case of <i>Toxoplasma gondii</i>, <i>Neospora caninum</i> or <i>Besnoitia besnoiti</i>, to ensure proper tachyzoite production, they need nutrients and cell building blocks. However, apicomplexans are auxotrophic for cholesterol, which is required for membrane biosynthesis. P-glycoprotein (P-gp) is a transmembrane transporter involved in xenobiotic efflux. However, the physiological role of P-gp in cholesterol metabolism is unclear. Here, we analyzed its impact on parasite proliferation in <i>T. gondii</i>-, <i>N. caninum</i>- and <i>B. besnoiti</i>-infected primary endothelial cells by applying different generations of P-gp inhibitors. Host cell treatment with verapamil and valspodar significantly diminished tachyzoite production in all three parasite species, whereas tariquidar treatment affected proliferation only in <i>B. besnoiti</i>. 3D-holotomographic analyses illustrated impaired meront development driven by valspodar treatment being accompanied by swollen parasitophorous vacuoles in the case of <i>T. gondii</i>. Tachyzoite and host cell pre-treatment with valspodar affected infection rates in all parasites. Flow cytometric analyses revealed verapamil treatment to induce neutral lipid accumulation. The absence of a pronounced anti-parasitic impact of tariquidar, which represents here the most selective P-gp inhibitor, suggests that the observed effects of verapamil and valspodar are associated with mechanisms independent of P-gp. Out of the three species tested here, this compound affected only <i>B. besnoiti </i>proliferation and its effect was much milder as compared to verapamil and valspodar.