Molecular characterization of Toxoplasma gondii in vivo dissemination and its interaction with the placental barrier

The apicomplexan parasite Toxoplasma gondii (Toxoplasma) can infect all warm-blooded animals, and ~30% of humans are chronically infected with this parasite. Toxoplasma belongs to the TORCH pathogens group (Toxoplasma gondii, Other, Rubella, Cytomegalovirus, and Herpes virus 1/2) that causes significant mortality and morbidity in infants worldwide. Congenital toxoplasmosis occurs when the parasite crosses the placenta of an infected pregnant woman and infects the fetus. In the US, approximately 500 to 5000 babies are born every year with congenital toxoplasmosis; additionally, there is an unknown number of acute abortions due to toxoplasmosis. The clinical manifestation of toxoplasmosis on the neonate is generally detected late after the delivery. Most infants will develop mental retardations, motor or cerebellar dysfunction, and chorioretinitis. However, despite the impact of this pathogen on the developing fetus, very little is known about the Toxoplasma-placenta interactions’ molecular basis. Toxoplasma can disseminate from the site of infection to specific tissues where it causes the initial acute stage of the infection. The parasite has specialized organelles called micronemes, rhoptries, and dense granules that secrete proteins, MICs, ROPs, and GRAs, respectively, facilitating the invasion and co-option of the host cell. Those secretory proteins could determinate the capacity of Toxoplasma to colonize the placenta and infect the fetus.

The Sangare lab uses Toxoplasma as a model to determine how pathogens disseminate and cross the placental barrier. We hypothesize that Toxoplasma possesses sets of genes allowing it to disseminate and cross the placental barrier. The rationale of our research program is to characterize the critical steps of Toxoplasma-placenta interaction before the fetus’s infection, which will likely provide new drug and vaccine targets against congenital toxoplasmosis. To attain the overall objective, The Sangare lab investigates three independent projects:

• Characterizing the molecular mechanism of Toxoplasma dissemination to the placenta.
• Understanding the molecular mechanism of Toxoplasma survival in placental tissues.
• Identification and characterization of Toxoplasma gene products that are essential to cross the placental barrier.

The results from this research program would reveal the mechanism by which a Toxoplasma and others TORCH pathogen reach and cross the placental barrier to infect the fetus. In addition, the results will provide a science-based framework for future drug targets and vaccine development to prevent Toxoplasma‘s vertical transmission.

1. Wang, Y, Hollingsworth, LR, Sangaré, LO, Paredes-Santos, TC, Krishnamurthy, S, Penn, BH et al.. Host E3 ubiquitin ligase ITCH mediates Toxoplasma gondii effector GRA35-triggered NLRP1 inflammasome activation and cell-autonomous immunity. mBio. 2024;15 (3):e0330223. doi: 10.1128/mbio.03302-23. PubMed PMID:38376248 PubMed Central PMC10936166.
2. Wang, Y, Hollingsworth, LR, Sangaré, LO, Paredes-Santos, TC, Krishnamurthy, S, Penn, BH et al.. Host E3 ubiquitin ligase ITCH mediates Toxoplasma gondii effector GRA35-triggered NLRP1 inflammasome activation and cell-autonomous immunity. bioRxiv. 2023; :. doi: 10.1101/2023.12.13.571530. PubMed PMID:38168400 PubMed Central PMC10760081.
3. Houngue, R, Sangaré, LO, Alayi, TD, Dieng, A, Bitard-Feildel, T, Boulogne, C et al.. Toxoplasma membrane inositol phospholipid binding protein TgREMIND is essential for secretory organelle function and host infection. Cell Rep. 2024;43 (1):113601. doi: 10.1016/j.celrep.2023.113601. PubMed PMID:38157297 .
4. Paredes-Santos, TC, Bitew, MA, Swale, C, Rodriguez, F, Krishnamurthy, S, Wang, Y et al.. Genome-wide CRISPR screen identifies genes synthetically lethal with GRA17, a nutrient channel encoding gene in Toxoplasma. PLoS Pathog. 2023;19 (7):e1011543. doi: 10.1371/journal.ppat.1011543. PubMed PMID:37498952 PubMed Central PMC10409377.
5. Krishnamurthy, S, Maru, P, Wang, Y, Bitew, MA, Mukhopadhyay, D, Yamaryo-Botté, Y et al.. CRISPR Screens Identify Toxoplasma Genes That Determine Parasite Fitness in Interferon Gamma-Stimulated Human Cells. mBio. 2023;14 (2):e0006023. doi: 10.1128/mbio.00060-23. PubMed PMID:36916910 PubMed Central PMC10128063.
6. Rahman, Z, Khuroo, T, Mohamed, EM, Dharani, S, Kayalar, C, Kuttolamadom, MA et al.. Pyrimethamine 3D printlets for pediatric toxoplasmosis: design, pharmacokinetics, and anti-toxoplasma activity. Expert Opin Drug Deliv. 2023;20 (2):301-311. doi: 10.1080/17425247.2023.2169272. PubMed PMID:36639201 .
7. Sangaré, LO, Wang, Y, Arranz-Solís, D, Saeij, JPJ. CRISPR screen to determine the in vivo fitness of Toxoplasma genes. STAR Protoc. 2021;2 (2):100520. doi: 10.1016/j.xpro.2021.100520. PubMed PMID:34013213 PubMed Central PMC8113973.
8. Wang, Y, Sangaré, LO, Paredes-Santos, TC, Hassan, MA, Krishnamurthy, S, Furuta, AM et al.. Genome-wide screens identify Toxoplasma gondii determinants of parasite fitness in IFNγ-activated murine macrophages. Nat Commun. 2020;11 (1):5258. doi: 10.1038/s41467-020-18991-8. PubMed PMID:33067458 PubMed Central PMC7567896.
9. Wang, Y, Sangaré, LO, Paredes-Santos, TC, Saeij, JPJ. Toxoplasma Mechanisms for Delivery of Proteins and Uptake of Nutrients Across the Host-Pathogen Interface. Annu Rev Microbiol. 2020;74 :567-586. doi: 10.1146/annurev-micro-011720-122318. PubMed PMID:32680452 PubMed Central PMC9934516.
10. Mukhopadhyay, D, Sangaré, LO, Braun, L, Hakimi, MA, Saeij, JP. Toxoplasma GRA15 limits parasite growth in IFNγ-activated fibroblasts through TRAF ubiquitin ligases. EMBO J. 2020;39 (10):e103758. doi: 10.15252/embj.2019103758. PubMed PMID:32293748 PubMed Central PMC7232000.