Poster Presentation CD1-MR1 Workshop 2025

MAIT cell activation in HIV-induced neuroinflammation (#170)

Emily M. Slaby 1 2 , Decha Silsorn 3 , Dutsadee Inthawong 3 , Jumpol Sopanaporn 3 , Sandhya Vasan 1 2 , Michael Corley 4 , Dominic Paquin Proulx 1 2
  1. Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
  2. Center of Infectious Disease Research, Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
  3. Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
  4. Department of Medicine, Division of Infectious Diseases, Weill Cornell Medicine, New York City, NY, United States

Despite effective antiretroviral therapy (ART), HIV-associated neurocognitive disorders (HAND) persist in some people living with HIV. Growing evidence from mice studies suggests a role for mucosal-associated invariant T (MAIT) cells, innate-like T cells recognizing MHC class I–related protein (MR1)-presented riboflavin metabolites (5-OP-RU), in brain homeostasis. We hypothesize that MAIT cells contribute to HAND pathogenesis via gut-central nervous system interactions. To assess the capacity of human neural cell lines (astrocyte, microglia, and neuron) to present antigens by MR1, we pre-incubated neural cells with 5-OP-RU before adding human MAIT cells and evaluated their expression of activation markers by flow cytometry after 24 hours. Microglia- and astrocyte-like cells incubated with 5-OP-RU induced MR1-dependent MAIT cell activation evidenced by increased CD69, CD107a, CCL3, and Granzyme B expression compared to untreated and MR1-blocking conditions. Thus, microglia and astrocytes have the potential to interact with MAIT cells via MR1. To investigate if cerebrospinal fluid (CSF) and plasma from simian-human immunodeficiency virus (SHIV)-infected non-human primates (NHP) on ART, post-analytical treatment interruption, and untreated chronic infection (CHI) could activate MAIT cells, CSF or plasma was added to enriched human MAIT cells in the presence or absence of MR1 blocking. Both plasma and CSF from CHI induced MR-1 dependent MAIT cell activation compared to plasma or CSF from ART-treated NHP, suggesting that MAIT cell antigen can reach the CSF during untreated HIV infection. Plasma-mediated MAIT cell activation correlated negatively with plasma neopterin and positively with IL-8 concentrations. There were no significant correlations to CSF-mediated MAIT cell activation or viral load. This would suggest a complex relationship between inflammation and MAIT cells, warranting further investigation into mechanisms. These findings suggest a potential role for MAIT cells in CNS inflammation during HIV, highlighting the importance of gut-immune-brain interactions in HAND pathogenesis.