Aspergillus fumigatus gliotoxin inhibits LC3-associated phagocytosis in macrophages in a calcium-dependent manner.

As a pivotal secondary metabolite of Aspergillus fumigatus (A. fumigatus), gliotoxin (GT) has many toxicological effects on mammalian cells; however, its function on LC3-associated phagocytosis (LAP) induced by A. fumigatus in macrophages is poorly understood. Here, it was found that pretreatment of macrophages with GT can significantly attenuate the conversion of LC3-II. In parallel, the expression of Rubicon, the putative indicator of LAP in macrophages was dampened in a similar trend. Loss of ability to produce GT made the conidia of gliPΔ mutant of A. fumigatus induce more LC3-II conversion in THP1 cells, which could be inhibited by exogenous GT. Comparative transcriptomic analysis showed that GT can promote the expression of MAPK10, and the calcium-releases regulatory pathway was enriched between the differentially expressed genes. Further, GT promotes the release of ROS at a concentration of 50 ng/ml and inhibition by GT on LC3-II production in macrophages during A. fumigatus infection could be restored by pretreatment with calcium inhibitors but not affected by the inhibitors for JNK and siRNA for MAKP10. Collectively, our data demonstrated that GT exerts an inhibitory effect on LC3-associated phagocytosis in macrophages via a calcium-dependent mechanism, and MAPK10 exists downstream of LAP.