Functional MAIT Cells Are Associated With Reduced Simian-Human Immunodeficiency Virus Infection

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Mucosa-associated invariant T (MAIT) cells are innate-like T cells recognizing microbial metabolites via MR1.
• MAIT cell roles in bacterial defense are known, but their function in viral infections like HIV/SIV remains unclear.
• Understanding MAIT cell dynamics is crucial for developing novel immunotherapies against viral pathogens.

Purpose of the Study:

• To investigate the phenotype, distribution, and function of MAIT cells during chronic SHIV infection in rhesus macaques.
• To assess the association between MAIT cell characteristics and plasma viral RNA levels.
• To explore the impact of cytokine treatments on MAIT cell function in vivo.

Main Methods:

• Characterization of MAIT cells (CD161+, TCRVα-7.2+) in blood and mucosal tissues of healthy and SHIV-infected macaques.
• Flow cytometry analysis of MAIT cell phenotype, proliferation, and cytotoxicity markers.
• Correlation analysis between MAIT cell frequency/function and viral load, CD4+ T cell counts, and serum immunoreactivity.

Main Results:

• MAIT cells in SHIV-infected macaques exhibited a memory phenotype with increased proliferative and cytotoxic potential.
• MAIT cell frequency was enriched in blood but not the rectum, inversely correlating with plasma viral RNA levels.
• MAIT cells were significantly enriched in non-lymphoid tissues and responded to microbial products and specific cytokines (IL-7, IL-12, IL-18).

Conclusions:

• MAIT cells display altered distribution and enhanced functional capacity during chronic SHIV infection, correlating with viral control.
• IL-7 promotes MAIT cell proliferation, while IL-12 and IL-18 enhance their cytolytic function.
• Targeted cytokine-based therapies could potentially enhance MAIT cell-mediated immunity against chronic HIV infection.