Cytokine profiling in chronic neurotoxoplasmosis caused by the knock-out parasite for the bradyzoite marker P18 in the C57BL-6J mouse model -

Abstract

Descriptive Statement: Toxoplasma gondii is an obligate intracellular parasite that forms chronic life-long bradyzoite cysts in the brain of infected humans. Our lab generated the PruΔKU80ΔP18 strain in which the bradyzoite marker P18 was deleted and found that this strain displays a higher capacity of cyst formation when compared to the wild type strain PruΔKU80. Since the host immune response is the key player of controlling the switch between acute and chronic toxoplasmosis, we have investigated this immune response, through cytokine profiling, against the P18 knock-out strain using the C57BL-6J susceptible mouse model. Introduction: T. gondii is capable of establishing an acute and-or latent chronic infection in a wide variety of hosts. IFN-γ is key driver that tightly controls the chronic cerebral infection, and activates microglial cells as well as other brain reaching wandering cells such as macrophages to produce nitric oxide (NO). NO, along with pro- and anti-inflammatory cytokines, triggers the conversion to bradyzoite forms and is critically important to control infection in C57BL-6 mice. We investigated the cyst forming capacity and the immune response upon infection with PruΔKU80ΔP18 and PruΔKU80 strains in the brains of the susceptible C57BL-6J mice by measuring transcription levels of BAG-1, a bradyzoite marker in the brains of mice infected with either strain and comparing these levels as well as the transcription levels of various cytokines involved in the immune response against T. gondii. Methods: C57BL-6 mice were infected with PruΔKU80ΔP18 and PruΔKU80 strains and were treated with sulfadiazine to overcome the acute phase of toxoplasmosis. Blood was collected on day 7 post infection to verify the acute infection by the western blotting. Mice were sacrificed on weekly basis from week 2 until week 5. Total mRNA was extracted from the brains, and different immunomodulatory cytokines and chemokines (MCP-1, IL-12, IFN-γ, TNFα