Type 2 immune history trains lung macrophages for viral disease tolerance.

Type 2 immune history induces lung macrophages that confer viral disease tolerance, with 100% survival in previously infected mice challenged with lethal influenza.

• Why it matters: Understanding how prior immune responses influence disease severity can reveal new strategies to promote tolerance and reduce immunopathology during respiratory viral infections.
• What they did: The study used a mouse model where Nippostrongylus brasiliensis infection expanded nerve- and airway-associated macrophages (NAMs), which were then challenged with lethal H1N1 influenza, demonstrating that conditioned NAMs are necessary and sufficient for protection.
• The result: Conditioned NAMs reduced tissue damage and promoted repair without affecting viral load, suggesting that trained immunity in lung macrophages can enable disease tolerance and offer therapeutic potential for severe respiratory infections.