Dual role of mucosal-associated invariant T cells (MAIT) in asthma.

Objective: Mucosal-associated invariant T cells (MAIT) are the predominant type of innate-like T cells in humans, and they represent a unique subset of microbiota-dependent invariant T cells. This Commentary reviews recent clinical studies and animal model research elucidating the multifaceted roles of MAIT cells in asthma.

Method: A literature search was performed using PubMed and Google Scholar, and covered the period from 1960 to 2024. The search yielded more than 50 articles, and only essential original research articles and selected review articles were evaluated.

Results: Recent studies indicate that MAIT cell-derived effector molecules may play dual roles in asthma and allergic airway inflammation. While MAIT cells can produce the anti-inflammatory enzyme IL4I1 and the Th1 cytokine IFN-γ to repress allergic airway inflammation and airway hyperresponsiveness (AHR), they may also secrete IL-17. Which induces neutrophil infiltration and exacerbates AHR. In addition, some clinical studies from the literature search revealed a negative association between MAIT cell abundance and asthma. Regarding allergic airway inflammation, mouse model studies suggested that MAIT cells may play a protective role.

Conclusion: These findings raise critical questions as to whether MAIT cells are friend or foe in asthma, and whether distinct subsets of MAIT cells play different roles in allergic airway inflammation. Further studies are needed to better understand the implication of MAIT cells in asthma pathogenesis, particularly in patients with severe asthma.