Proteomic Portrait of Degranulation Program in Human Circulating Neutrophils Upon Multi-Inflammatory and Infectious Activation.

Neutrophils respond rapidly to inflammation and infection via defense mechanisms, including degranulation, reactive oxygen species production, and neutrophil extracellular trap formation (known as "NETosis"). As the most abundant neutrophil components, granule proteins constitute the major mediators of neutrophil effector functions and likely orchestrate their functional diversity. However, a systematic profile of these proteins, particularly their temporal release dynamics during inflammatory responses, remains uncharacterized. Here, we performed a "multistate" proteomic study to explore circulating neutrophils' dynamic responses to diverse infectious and inflammatory signals over time. Circulating neutrophils exhibited both conserved and stimulus-specific protein expression programs. Through integrated characterization of the cellular and secretory proteome landscapes, we delineated the release patterns of canonical granule proteins and identified inflammatory mediators, including soluble membrane receptors. Notably, granule membrane receptors were translocated to the cell surface and shed via proteolytic cleavage, highlighting their dynamic regulation and diversity. These findings revealed the complexity of the neutrophil degranulation program, demonstrating its stimulus-dependent and temporally layered nature. Our study provides a functional atlas of neutrophil degranulation upon inflammation, which would strengthen our understanding of neutrophil activation in inflammation and facilitate the exploration of inflammation management therapies.