Siglec-E promotes β2-integrin-dependent NADPH oxidase activation to suppress neutrophil recruitment to the lung

Sarah J. McMillan, Ritu S. Sharma, Hannah E. Richards, Vikas Hegde, Paul R. Crocker (Lead / Corresponding author)

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    Siglec-E is a sialic acid-binding Ig-like lectin expressed on murine myeloid cells. It has recently been shown to function as a negative regulator of ß2-integrin-dependent neutrophil recruitment to the lung following exposure to lipopolysaccharide (LPS). Here, we demonstrate that siglec-E promoted neutrophil production of reactive oxygen species (ROS) following CD11b ß2-integrin ligation with fibrinogen in a sialic acid-dependent manner, but had no effect on ROS triggered by a variety of other stimulants. Siglec E promotion of ROS was likely mediated via Akt activation, since siglec-E-deficient neutrophils plated on fibrinogen exhibited reduced phosphorylation of Akt and the Akt inhibitor, MK2206, blocked fibrinogen-induced ROS. In vivo imaging showed that siglec-E also promoted ROS in acutely inflamed lungs following exposure of mice to LPS. Importantly, siglec E-promoted ROS were required for its inhibitory function, as the NADPH oxidase inhibitor, apocynin, reversed the siglec-E-mediated suppression of neutrophil recruitment and blocked neutrophil ROS production in vitro. Taken together, these results demonstrate that siglec E functions as an inhibitory receptor of neutrophils via positive regulation of NADPH oxidase activation and ROS production. Our findings have implications for the inhibitory role of siglec-9 on human neutrophils in sepsis and acute lung injury.

    Original languageEnglish
    Pages (from-to)20370-20376
    Number of pages7
    JournalJournal of Biological Chemistry
    Issue number29
    Publication statusPublished - 18 Jul 2014


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