IFN-γ–induced trained immunity enhances killing of priority pathogens in healthy and genetically vulnerable individuals
Dearbhla M. Murphy, Isabella Batten, Aoife O’Farrell, Simon R. Carlile, Sinead A. O’Rourke, Chloe Court, Brenda Morris, Gina Leisching, Gráinne Jameson, Sarah A. Connolly, Adam H. Dyer, John P. McGrath, Emma McNally, Olivia Sandby-Thomas, Anjali Yennemadi, Conor M. Finlay, Clíona Ní Cheallaigh, Jean Dunne, Cilian Ó Maoldomhnaigh, Laura E. Gleeson, Aisling Dunne, Nollaig Bourke, Reinout van Crevel, Donal J. Cox, Niall Conlon, Arjun Raj, Rachel M. McLoughlin, Joseph Keane, Sharee A. Basdeo
Dearbhla M. Murphy, Isabella Batten, Aoife O’Farrell, Simon R. Carlile, Sinead A. O’Rourke, Chloe Court, Brenda Morris, Gina Leisching, Gráinne Jameson, Sarah A. Connolly, Adam H. Dyer, John P. McGrath, Emma McNally, Olivia Sandby-Thomas, Anjali Yennemadi, Conor M. Finlay, Clíona Ní Cheallaigh, Jean Dunne, Cilian Ó Maoldomhnaigh, Laura E. Gleeson, Aisling Dunne, Nollaig Bourke, Reinout van Crevel, Donal J. Cox, Niall Conlon, Arjun Raj, Rachel M. McLoughlin, Joseph Keane, Sharee A. Basdeo
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Research Article Immunology Infectious disease

IFN-γ–induced trained immunity enhances killing of priority pathogens in healthy and genetically vulnerable individuals

Abstract

Infectious diseases remain a global health challenge, driven by increasing antimicrobial resistance and the threat of emerging epidemics. Mycobacterium tuberculosis and Staphylococcus aureus are leading causes of mortality worldwide. Trained immunity — a form of innate immune memory — offers a promising approach to enhance pathogen clearance. Here, we demonstrate that IFN-γ induces trained immunity in human monocytes through a mechanism involving mTORC1 activation, glutaminolysis, and epigenetic remodeling. Macrophages derived from IFN-γ–trained monocytes exhibited increased glycolytic activity with enhanced cytokine and chemokine responses upon stimulation or infection. Crucially, trained macrophages had increased production of reactive oxygen species, which mediated enhanced bactericidal activity against methicillin-resistant S. aureus and M. tuberculosis. Furthermore, ATAC-sequencing analysis of IFN-γ–trained macrophages revealed increased chromatin accessibility in regions associated with host defense. Last, IFN-γ training restored impaired innate responses in macrophages from individuals homozygous for the TIRAP 180L polymorphism, a genetic variant associated with increased susceptibility to infection. These findings establish IFN-γ as a potent inducer of trained immunity in human monocytes and support its potential as a host-directed strategy to strengthen antimicrobial defenses, particularly in genetically susceptible individuals and high-risk clinical contexts.

Authors

Dearbhla M. Murphy, Isabella Batten, Aoife O’Farrell, Simon R. Carlile, Sinead A. O’Rourke, Chloe Court, Brenda Morris, Gina Leisching, Gráinne Jameson, Sarah A. Connolly, Adam H. Dyer, John P. McGrath, Emma McNally, Olivia Sandby-Thomas, Anjali Yennemadi, Conor M. Finlay, Clíona Ní Cheallaigh, Jean Dunne, Cilian Ó Maoldomhnaigh, Laura E. Gleeson, Aisling Dunne, Nollaig Bourke, Reinout van Crevel, Donal J. Cox, Niall Conlon, Arjun Raj, Rachel M. McLoughlin, Joseph Keane, Sharee A. Basdeo

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Figure 4

IFN-γ training increases the capacity of MDM to kill S. aureus and M. tuberculosis by enhancing ROS production.

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IFN-γ training increases the capacity of MDM to kill S. aureus and M. tu...
Enriched monocytes were left untrained (UT; white) or trained with IFN-γ (10 ng/mL; gray) for 24 hours. Cells were differentiated into MDM. On day 7, MDM were infected with M. tuberculosis (H37Rv; MOI 1–5) (A and B), stimulated with irradiated M.tb (10 μg/mL) (G), or infected with S. aureus (USA300; MOI 100:1) (H–P) for the indicated times. (A and B) Bacterial M. tuberculosis burden within MDM 3 and 48 hours after infection. (C–F) Relative expression (to untrained) of CYBA (C), CYBB (D), NCF1 (E), or NCF2 (F) in uninfected MDM on day 7 (qPCR). (G) MDM were stimulated with irradiated M.tb for 4 hours, and ROS (DHR123; relative to unstimulated MDM) was measured (flow cytometry). (H–K) TNF (H), IL-6 (I), IL-1β (J), or IL-10 (K) (ELISA) 24 hours after S. aureus infection. (L) MDM infected with CFSE-labeled S. aureus (%). (M) Intracellular bacterial S. aureus burden within MDM 1, 4, or 24 hours after gentamicin. (N) Spearman’s r correlation matrix: correlation of reduced CFU with IL-1β, TNF, IL-6, IL-10, CXCL1, or MIP-1α production. (O) MDM were infected with S. aureus alone or in the presence of NAC (10 mM) for 4 hours, and ROS was measured (flow cytometry). (P) Fold change in CFU/mL of untrained or IFN-γ–trained (stripes) MDM infected with S. aureus 1, 4, or 24 hours after gentamicin in healthy controls (HC; white) versus MDM from a patient with chronic granulomatous disease (CGD; green). Each dot represents an individual donor, n = 4 (A–G), n = 7 (H–K, M, and N), n = 5 (L), n = 6 (O), or HC n = 7, CGD n = 1 (P). Data are graphed as paired data joined by a line or the mean value ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, paired t test (A–L) or 2-way ANOVA with Šidák’s multiple-comparison test (M), uncorrected Fisher’s LSD test (O), or Tukey’s multiple-comparison test (P).