Highlights of IMMUNOLOGY2026™ - Invited Program Recordings-Environmental dysregulation of MAIT cells in obesity

Video Transcription

Video Summary

The speaker discussed how obesity, a chronic relapsing disease, is linked not only to diabetes and cancer but also to increased susceptibility to bacterial, viral, fungal, and parasitic infections. Their research focuses on unconventional T cells, especially MAIT cells and gamma delta T cells, which normally help protect against infection.<br /><br />In people living with obesity, both MAIT and Vδ2 gamma delta T cells are reduced in blood and adipose tissue and show impaired function. MAIT cells lose interferon-gamma production, gain IL-17 skewing, and have defective metabolism due to reduced glutamine uptake. Glutamine was shown to stabilize MYC, which drives glycolysis, protein synthesis, and effector function; without it, MAIT cells become metabolically paralyzed and less protective.<br /><br />Similarly, Vδ2 gamma delta T cells in obesity show reduced amino acid transport, lower CD98/LAMTOR5/mTORC1 signaling, decreased protein translation, and impaired production of interferon-gamma, TNF, and granzyme B. <br /><br />Importantly, bariatric surgery restored much of this immune dysfunction, including nutrient sensing pathways and effector functions. The overall message was that obesity creates a nutrient-poor inflammatory environment that disables protective T-cell responses, and improving the obesity state can reverse these immune defects.

Keywords

obesity

MAIT cells

gamma delta T cells

immune dysfunction

glutamine metabolism

bariatric surgery

infection susceptibility