DLL4+ Neutrophils Induce Alveolar Macrophages to Cause ADAM-17-mediated Endothelial Barrier Disruption and the Increase of ICAM1hiCXCR1lo Neutrophils in Sepsis.

Authors

Hui Jin, Saoirse Holland, Alok Jha, Monowar Aziz, Ping Wang

Published in

Journal of leukocyte biology. Jul 10, 2026. Epub Jul 10, 2026.

Abstract

Sepsis remains a leading cause of death. Reverse migrated (RM) neutrophils, characterized as ICAM1hiCXCR1lo, have been recognized as a key driver of systemic inflammation and organ injury in sepsis. We have recently discovered a distinct DLL4+ subset of neutrophils that accumulate in the lungs, contributing to lung injury; however, the underlying mechanism is less understood. In sepsis, ICAM1hiCXCR1lo neutrophils, being hyperactive, were shown to be detrimental. Here, we investigated how DLL4+ neutrophils activate alveolar macrophages (AMs) to cause endothelial cell barrier disruption and promote neutrophil reverse migration. AMs were treated with DLL4+ neutrophils or recombinant mouse DLL4 (rmDLL4), and a disintegrin and metalloprotease (ADAM17) generated by AMs was assessed at both mRNA and protein levels. Conditioned medium was subsequently applied to pulmonary vascular endothelial cells (PVECs); junctional adhesion molecule-C (JAM-C) protein was detected by Western blot assays, and ICAM1hiCXCR1lo neutrophils were detected by flow cytometry. We demonstrate that during sepsis induced by cecal ligation and puncture (CLP), DLL4+ neutrophils interact with AMs via the Notch1 pathway, leading to increase of ADAM17 expression. ADAM17 decreased JAM-C on PVECs, causing endothelial barrier disruption and ICAM1hiCXCR1lo neutrophils generation. Small-molecule inhibitor of ADAM17 effectively preserved pulmonary endothelial barrier integrity, and reduced ICAM1hiCXCR1lo neutrophils accumulation. Importantly, we have developed a novel DLL4-Notch1 inhibitory peptide (NDI) that effectively suppresses ADAM17 expression, restores JAM-C, and reduces ICAM1hiCXCR1lo neutrophils accumulation in sepsis. These findings identify DLL4+ neutrophils as a critical inflammatory mediator that exacerbate systemic inflammation and worsen sepsis, highlight the DLL4-Notch1-ADAM17 axis as a promising therapeutic target.

PMID:
42430668
Bibliographic data and abstract were imported from PubMed on 11 Jul 2026.

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