Aspergillus fumigatus-derived gliotoxin impairs innate immune cell activation through modulating lipid mediator production in macrophages

Gliotoxin (GT), a major secondary metabolite and virulence factor of Aspergillus fumigatus, suppresses innate immunity and supports the evasion of host immune responses. Recently, we revealed that GT blocks leukotriene (LT)B4 formation by directly inhibiting LTA4 hydrolase (LTA4H) in activated human neutrophils and monocytes. Here, we elucidated the impact of GT on LTB4 biosynthesis and the complex lipid mediator network in human M1- and M2-like monocyte-derived macrophage (MDM) subtypes and studied the respective consequences for innate immune cell functions. Notably, in resting MDMs, GT elicited prostaglandin and 12/15-lipoxygenase product formation, although less efficient than bacterial exotoxins. In activated MDM, LTB4 formation was effectively suppressed by GT, connected to impaired macrophage phagocytic activity, and detrimental consequences for neutrophil movement and migration. Conclusively, GT impairs functions of activated innate immune cells through suppression of LTB4 formation, while GT may prime the immune system by provoking prostaglandin formation and 12/15-lipoxygenase-derived LM.