Chemoproteomic Profiling of Itaconation by Bioorthogonal Probes in Inflammatory Macrophages

Itaconate is an anti-inflammatory metabolite involved in pathogen–macrophage interactions, but the mechanisms underlying its effect are not fully understood. Competitive cysteine profiling has been performed to interrogate itaconate's reactivity in cell lysates, but methods for analyzing targets of itaconation directly in living macrophages are still lacking. In this work, we developed a specific bioorthogonal probe, itaconate–alkyne (ITalk), for quantitative and site-specific chemoproteomic profiling of itaconation in inflammatory macrophages. ITalk recapitulates the anti-inflammatory property of itaconate and enables biochemical evaluation and proteomic analysis of its direct targets. Our study delineates the widespread landscape of itaconate substrates, providing a versatile tool and comprehensive resource for investigating its function.