Glutamate utilization promotes meningococcal survival in vivo through avoidance of the neutrophil oxidative burst

Area of Science:

• Immunology
• Microbiology
• Molecular Biology

Background:

• Polymorphonuclear neutrophil leucocytes (PMNs) are crucial for innate immunity against bacterial pathogens.
• Neisseria meningitidis is a significant cause of bacterial meningitis and septicaemia.
• Most bacteria are killed by PMNs, but some pathogens have evolved evasion mechanisms.

Purpose of the Study:

• To investigate the mechanism by which Neisseria meningitidis evades killing by PMNs.
• To identify the role of L-glutamate uptake in N. meningitidis survival against host immune defenses.
• To understand how N. meningitidis utilizes L-glutamate to counteract oxidative stress during infection.

Main Methods:

• Investigated the interaction between N. meningitidis and PMNs.
• Utilized genetic approaches to study the GltT uptake system in N. meningitidis.
• Measured reactive oxygen species (ROS) production and bacterial survival.
• Analyzed the conversion of L-glutamate to glutathione and its role in redox homeostasis.

Main Results:

• N. meningitidis evades killing by PMNs through the acquisition of L-glutamate via the GltT uptake system.
• L-glutamate uptake facilitates bacterial resistance to PMN-derived reactive oxygen species.
• N. meningitidis converts L-glutamate to glutathione, a molecule that maintains intracellular redox potential and protects against oxidative damage.
• This L-glutamate-dependent antioxidant mechanism contributes to N. meningitidis-induced bacteraemia.

Conclusions:

• The GltT-mediated uptake of L-glutamate is essential for Neisseria meningitidis to evade PMN-mediated killing.
• Glutathione synthesis, fueled by acquired L-glutamate, is a key survival strategy for N. meningitidis against oxidative stress.
• This mechanism highlights a critical factor enabling N. meningitidis to establish bacteraemia and cause severe infections.