Activated Brain Endothelial Cells Cross-Present Malaria Antigen

Area of Science:

• Immunology
• Neuroscience
• Infectious Diseases

Background:

• Cerebral malaria (CM) pathogenesis involves parasite-specific CD8+ T cells.
• CD8+ T cells are hypothesized to kill brain endothelial cells internalizing Plasmodium berghei ANKA (PbA) antigens.

Purpose of the Study:

• To identify the specific brain cells responsible for antigen cross-presentation in murine cerebral malaria.
• To investigate the mechanism and susceptibility of brain endothelial cells to CD8+ T cell-mediated killing.

Main Methods:

• Utilized a murine model of cerebral malaria (PbA infection).
• Employed reporter cells with epitope-specific T cell receptors to assess cross-presentation.
• Investigated antigen cross-presentation by primary brain endothelial cells and other brain cell types in vitro and in vivo.
• Analyzed the role of IFNγ stimulation and proteasome- and TAP-dependent pathways.
• Examined phagocytosis of parasite strains and merozoites by endothelial cells.

Main Results:

• Confirmed brain endothelial cells, not pericytes or microglia, are responsible for PbA antigen cross-presentation in vivo.
• Demonstrated that PbA antigen cross-presentation by brain endothelial cells in vitro confers susceptibility to CD8+ T cell killing.
• Identified IFNγ stimulation as essential for brain endothelial cross-presentation, occurring via proteasome and TAP.
• Observed less efficient phagocytosis and cross-presentation of non-CM-inducing parasite strains compared to PbA.
• Found that free merozoites are the primary antigen source and are avidly phagocytosed by endothelial cells, including a human cell line.

Conclusions:

• This study provides the first evidence of antigen cross-presentation by brain endothelial cells in cerebral malaria.
• Results suggest that targeting merozoite phagocytosis or antigen processing could be effective therapeutic strategies for cerebral malaria.