Identification of organs of origin of macrophages that produce presepsin via neutrophil extracellular trap phagocytosis.

Abstract

Presepsin (P-SEP) is a specific biomarker for sepsis. Monocytes produce P-SEP by phagocytosing neutrophil extracellular traps (NETs). Herein, we investigated whether M1 macrophages (M1 M&#x3a6;s) are the primary producers of P-SEP after NET phagocytosis. We co-cultured M1 M&#x3a6;s and NETs from healthy participants, measured P-SEP levels in the culture medium supernatant, and detected P-SEP using western blotting. When NETs were co-cultured with M1 M&#x3a6;s, the P-SEP level of the culture supernatant was high. Notably, we demonstrated, for the first time, the intracellular kinetics of P-SEP production by M1 M&#x3a6;s via NET phagocytosis: M1 M&#x3a6;s produced P-SEP intracellularly 15&#xa0;min after NET phagocytosis and then released it extracellularly. In a sepsis mouse model, the blood NET ratio and P-SEP levels, detected using ELISA, were significantly increased (p&#x2009;<&#x2009;0.0001). Intracellular P-SEP analysis via flow cytometry demonstrated that lung, liver, and kidney M&#x3a6;s produced large amounts of P-SEP. Therefore, we identified these organs as the origin of M1 M&#x3a6;s that produce P-SEP during sepsis. Our data indicate that the P-SEP level reflects the trend of NETs, suggesting that monitoring P-SEP can be used to both assess NET-induced organ damage in the lungs, liver, and kidneys during sepsis and determine treatment efficacy.