The complex involvement
of neutrophils in inflammatory diseases
makes them intriguing but challenging targets for therapeutic intervention.
Here, we tested the hypothesis that varying endocytosis capacities
would delineate functionally distinct neutrophil subpopulations that
could be specifically targeted for therapeutic purposes. By using
uniformly sized (∼120 nm in diameter) albumin nanoparticles
(ANP) to characterize mouse neutrophils
in vivo
,
we found two subsets of neutrophils, one that readily endocytosed
ANP (ANP
high
neutrophils) and another that failed to endocytose
ANP (ANP
low
population). These ANP
high
and ANP
low
subsets existed side by side simultaneously in bone marrow,
peripheral blood, spleen, and lungs, both under basal conditions and
after inflammatory challenge. Human peripheral blood neutrophils showed
a similar duality. ANP
high
and ANP
low
neutrophils
had distinct cell surface marker expression and transcriptomic profiles,
both in naive mice and in mice after endotoxemic challenge. ANP
high
and ANP
low
neutrophils were functionally distinct
in their capacities to kill bacteria and to produce inflammatory mediators.
ANP
high
neutrophils produced inordinate amounts of reactive
oxygen species and inflammatory chemokines and cytokines. Targeting
this subset with ANP loaded with the drug piceatannol, a spleen tyrosine
kinase (Syk) inhibitor, mitigated the effects of polymicrobial sepsis
by reducing tissue inflammation while fully preserving neutrophilic
host-defense function.