Granzyme B expression by CD8+ T cells is required for the development of experimental cerebral malaria

Area of Science:

• Immunology
• Infectious Diseases
• Neuroscience

Background:

• Parasite burden correlates with malaria severity and mortality.
• CD8(+) T cells and parasite load contribute to experimental cerebral malaria (ECM) pathogenesis via incompletely understood mechanisms.

Purpose of the Study:

• To elucidate the role of CD8(+) T cells, granzyme B (GzmB), and parasite burden in ECM development.
• To investigate the mechanisms underlying CD8(+) T cell-mediated pathology in the brain during malaria.

Main Methods:

• Utilized knockout mice lacking GzmB (gzmB(-/-)) and wild-type mice.
• Adoptive transfer of antigen-specific CD8(+) T cells.
• Quantified parasite burden in the brain.
• Assessed T cell responses (CD4(+) and CD8(+)) and cytokine production (IFN-γ).

Main Results:

• The majority of brain-infiltrating CD8(+) T cells expressed GzmB.
• gzmB(-/-) mice showed reduced brain parasite loads and protection from ECM, linked to enhanced CD4(+) T cell responses.
• ECM induction in mice required a critical threshold of antigen-specific CD8(+) T cells and was dependent on CD8(+) T cell-derived perforin and GzmB, but not IFN-γ.
• A reciprocal relationship exists between parasite burden and CD8(+) T cell activation in the brain, sustaining ECM.

Conclusions:

• CD8(+) T cell-derived perforin and GzmB are essential mediators of ECM.
• Parasite burden and CD8(+) T cell activity are interdependent, dictating ECM onset and severity.
• Targeting CD8(+) T cell cytotoxic molecules may offer therapeutic strategies for severe malaria.