Targeting Nlrp3 And Staphylococcal Pore-Forming Toxin Receptors In Human-Induced Pluripotent Stem Cell-Derived Macrophages

Staphylococcus aureuscauses necrotizing pneumonia by secreting toxins such as leukocidins that target front-line immune cells. The mechanism by which leukocidins kill innate immune cells and trigger inflammation duringS. aureuslung infection, however, remains unresolved. Here, we explored human-induced pluripotent stem cell-derived macrophages (hiPSC-dMs) to study the interaction of the leukocidins Panton-Valentine leukocidin (PVL) and LukAB with lung macrophages, which are the initial leukocidin targets duringS. aureuslung invasion. hiPSC-dMs were susceptible to the leukocidins PVL and LukAB and both leukocidins triggered NLPR3 inflammasome activation resulting in IL-1 beta secretion. hiPSC-dM cell death after LukAB exposure, however, was only temporarily dependent of NLRP3, although NLRP3 triggered marked cell death after PVL treatment. CRISPR/Cas9-mediated deletion of the PVL receptor, C5aR1, protected hiPSC-dMs from PVL cytotoxicity, despite the expression of other leukocidin receptors, such as CD45. PVL-deficientS. aureushad reduced ability to induce lung IL-1 beta levels in human C5aR1 knock-in mice. Unexpectedly, inhibiting NLRP3 activity resulted in increased wild-typeS. aureuslung burdens. Our findings suggest that NLRP3 induces macrophage death and IL-1 beta secretion after PVL exposure and controlsS. aureuslung burdens.