Macrophage migration inhibitory factor regulates innate γδ T-cell responses via IL-17 expression

Area of Science:

• Immunology
• Cell Biology

Background:

• Gamma delta T (γδ T) cells bridge innate and adaptive immunity, crucial for barrier defense.
• Macrophage migration inhibitory factor (MIF) regulates inflammatory responses and cell survival.
• IL-17 is a pro-inflammatory cytokine involved in host defense.

Purpose of the Study:

• To investigate the role of MIF in regulating γδ T-cell responses.
• To determine the impact of MIF deficiency on IL-17 production by γδ T cells.
• To explore the implications of altered γδ T-cell responses in infection models.

Main Methods:

• Comparison of wild-type and Mif-deficient (Mif-/-) γδ T cells.
• Stimulation with gram-positive exotoxins and Mycobacterium lipomannan.
• Analysis of cytokine production (IL-17, IL-1β, IL-23) and cell surface markers (IL-23R, IL-1R1).
• Assessment of transcription factors (RORγt, Sox13) in γδ T cells.
• Evaluation of survival rates and neutrophil accumulation in mouse models of toxic shock and Mycobacterium infection.
• γδ T cell depletion experiments.

Main Results:

• Mif-/- γδ T cells produced >10-fold higher IL-17 levels compared to wild-type cells upon stimulation.
• IL-17-producing γδ T (γδ17) cells in Mif-/- mice exhibited characteristic markers (IL-23R, IL-1R1, RORγt, Sox13).
• Mif-/- mice showed increased mortality, pulmonary neutrophil infiltration, and elevated IL-1β and IL-23 in a toxic shock model.
• γδ17 cell responses were also elevated in response to Mycobacterium lipomannan.
• Depletion of γδ T cells improved survival in lethal Mycobacterium infection and TSST-1-induced shock models.

Conclusions:

• MIF deficiency leads to a compensatory amplification of γδ17 cell responses.
• This dysregulated immune response has significant implications for IL-17-mediated pathology.
• Targeting MIF or γδ T cells could be a therapeutic strategy for gram-positive infections and related inflammatory conditions.