A genome‐wide screen identifies IRF2 as a key regulator of caspase‐4 in human cells

Caspase‐4, the cytosolic LPS sensor, and gasdermin D, its downstream effector, constitute the non‐canonical inflammasome, which drives inflammatory responses during Gram‐negative bacterial infections. It remains unclear whether other proteins regulate cytosolic LPS sensing, particularly in human cells. Here, we conduct a genome‐wide CRISPR/Cas9 screen in a human monocyte cell line to identify genes controlling cytosolic LPS‐mediated pyroptosis. We find that the transcription factor, IRF2, is required for pyroptosis following cytosolic LPS delivery and functions by directly regulating caspase‐4 levels in human monocytes and iPSC‐derived monocytes. CASP4 , GSDMD, and IRF2 are the only genes identified with high significance in this screen highlighting the simplicity of the non‐canonical inflammasome. Upon IFN‐γ priming, IRF1 induction compensates IRF2 deficiency, leading to robust caspase‐4 expression. Deficiency in IRF2 results in dampened inflammasome responses upon infection with Gram‐negative bacteria. This study emphasizes the central role of IRF family members as specific regulators of the non‐canonical inflammasome. Synopsis Sensing of cytosolic LPS by caspase‐4 triggers non‐canonical inflammasome activation. Interferon‐Regulatory Factor 2 (IRF2) is a transcription factor controlling caspase‐4 expression and LPS‐mediated pyroptosis in human cells. A genome‐wide screen identifies CASP4/GSDMD and IRF2 as required for cytosolic LPS‐mediated cell death. IRF2 directly binds the CASP 4 promoter and regulates its expression. In the presence of IFN‐γ, IRF1 and IRF2 control CASP 4 expression in a redundant manner. Graphical Abstract Sensing of cytosolic LPS by caspase‐4 triggers non‐canonical inflammasome activation. Interferon‐Regulatory Factor 2 (IRF2) is a transcription factor controlling caspase‐4 expression and LPS‐mediated pyroptosis in human cells.