The protozoan parasite Toxoplasma gondii infects approximately 2.5 billion people worldwide. Infection induces a rapid dissemination of parasites throughout the body followed by the formation of lifelong cysts within neurons of the host brain. Both stages require a dynamic immune response comprised of both innate and adaptive cells. Neutrophils are a primary responding cell to acute infection and have been observed in the brain during murine chronic infection. Previous studies investigating human neutrophils found that invasion by Toxoplasma tachyzoites inhibits apoptosis of neutrophils, prolonging their survival under inflammatory conditions. Here, we demonstrate the differentiation of two distinct subsets following exposure of human neutrophil-like-cells (HNLC) to Toxoplasma cysts. In vitro stimulation and imaging studies show cyst-specific induction of cytokines and cyst clearance by HNLCs. Further testing demonstrates that aged HNLCs perform less phagocytosis of cysts compared to non-aged HNLCs. In conclusion, this study identifies a novel response of HNLCs to Toxoplasma cysts and may indicate a role for neutrophils in the clearance of cysts during human infection with Toxoplasma.
Infection with the protozoan parasite Toxoplasma gondii leads to the formation of lifelong cysts in neurons of the brain that can have devastating consequences in the immunocompromised. However, despite the establishment of a chronic inflammatory state and infection-induced neurological changes, there are limited signs of clinical neuropathology resulting in an asymptomatic infection in the immunocompetent. This suggests the work of neuroprotective mechanisms to prevent clinical manifestations of disease. However, such sources of neuroprotection during infection remain largely unknown. This study identifies a population of neutrophils chronically present in the brain during Toxoplasma infection that express the neuroprotective molecules NRG-1, ErbB4, and MSR1. Further phenotyping of this population via flow cytometry and singe-cell RNA sequencing reveals two distinct subsets of neutrophils based on age that display functional heterogeneity. This includes cells transcriptionally prepared to function both as anti-parasitic effector cells and in a more alternative protective manner. Chronic depletion of neutrophils results in increased parasite burden and infection-induced vascular pathology. Lack of neutrophils during chronic infection also deleteriously affects neuronal regeneration and repair mechanisms. In conclusion, this work identifies and demonstrates a functionally diverse chronic neutrophil population that plays a dynamic role in controlling infection outcome in the CNS by balancing classical responses with neuroprotective functions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.