Modelling Toxoplasma gondii infection in human cerebral organoids

Abstract

Pluripotent stem cell-derived cerebral organoids have the potential to recapitulate the pathophysiology of in vivo human brain tissue, constituting a valuable resource for modelling brain disorders, including infectious diseases. Toxoplasma gondii, an intracellular protozoan parasite, infects most warm-blooded animals, including humans, causing toxoplasmosis. In immunodeficient patients and pregnant women, infection often results in severe central nervous system disease and fetal miscarriage. However, understanding the molecular pathophysiology of the disease has been challenging due to limited in vitro model systems. Here, we developed a new in vitro model system of T. gondii infection using human brain organoids. We observed that tachyzoites can infect human cerebral organoids and are transformed to bradyzoites and replicate in parasitophorous vacuoles to form cysts, indicating that the T. gondii asexual life cycle is efficiently simulated in the brain organoids. Transcriptomic analysis of T. gondii-infected organoids revealed the activation of the type I interferon immune response against infection. In addition, in brain organoids, T. gondii exhibited a changed transcriptome related to protozoan invasion and replication. This study shows cerebral organoids as physiologically relevant in vitro model systems useful for advancing the understanding of T. gondii infections and host interactions.

Advances in modelling the human microbiome–gut–brain axis in vitro

“…To overcome this challenge, efforts are being made to develop co-cultures of GI organoids with immune cells and/or enteric neurons [ 46 , 47 ]. Brain organoids have also been used to study neuro-immune, neuro-endocrine [ 48 ] and host–microbe interactions, including Zika virus, [ 49–51 ] Toxoplasma gondii , [ 52 ] congenital human cytomegalovirus (HCMV) [ 53 ] and Japanese encephalitis virus (JEV) [ 54 ]. Advances in (patient) iPSC-derived GI, ENS and brain organoids with vagal nerve neurons, as well as in methods to co-culture these components, could provide in the future a means to model the gut-brain connection and study the role of microbiota in various aspects of human health and disease [ 48 ].…”

Modeling SARS-CoV-2 infection in individuals with opioid use disorder with brain organoids

“… 149 , 215 , 216 Toxoplasmosa gondii (TG), an intracellular protozoan parasite with no vaccine or effective treatment, can cause several CNS diseases and neurodevelopmental defects such as mental retardation, seizures, and microcephalus. 150 , 217 , 218 The unusual asexual life cycle of TG, which alternates between tissue cyst-forming bradyzoites and inflammation-inducing tachyzoites, requires a heterogeneous cell population for replication that has had underwhelming results in 2D cultures. 150 , 218 – 220 Cerebral organoids were able to stimulate the complex TG asexual life cycle, including parasitophorous vacuoles that form cysts, and revealed that TG preferentially infects neuronal cells, astrocytes, and oligodendrocytes and primarily evokes an immune response from IFN-1.…”

“… 150 , 218 – 220 Cerebral organoids were able to stimulate the complex TG asexual life cycle, including parasitophorous vacuoles that form cysts, and revealed that TG preferentially infects neuronal cells, astrocytes, and oligodendrocytes and primarily evokes an immune response from IFN-1. 150 …”

“…150,217,218 The unusual asexual life cycle of TG, which alternates between tissue cyst-forming bradyzoites and inflammation-inducing tachyzoites, requires a heterogeneous cell population for replication that has had underwhelming results in 2D cultures. 150,[218][219][220] Cerebral organoids were able to stimulate the complex TG asexual life cycle, including parasitophorous vacuoles that form cysts, and revealed that TG preferentially infects neuronal cells, astrocytes, and oligodendrocytes and primarily evokes an immune response from IFN-1. 150 These studies have established brain organoids as a viable experimental infectious model, as summarized in Table 1.…”

The Stem Cell Revolution Revealing Protozoan Parasites’ Secrets and Paving the Way towards Vaccine Development

“…This cell line was differentiated into neuronal cells as confirmed by expression of neuronal markers, which were efficiently infected by tachyzoites and supported their replication and development of the cyst stage. A more in-depth understanding of the most inaccessible site of T. gondii infection was achieved by generating brain organoids from the hESC line H9 [ 75 ]. The correct structure and cell types were verified by staining for specific markers, identifying neurones, glia, astrocytes, oligodendrocytes by day 55 of differentiation.…”