Sepsis lethality via exacerbated tissue infiltration and TLR-induced cytokine production by neutrophils is integrin α3ß1-dependent.

ABSTRACT

Integrin-mediated migration of neutrophils to infected tissue sites is vital for pathogen clearance and therefore host survival. Although ß2 integrins have been shown to mediate neutrophil transendothelial migration during systemic and local inflammation, relatively little information is available regarding neutrophil migration in sepsis beyond the endothelial cell layer. In this study, we report that integrin α3ß1 (VLA-3; CD49c/CD29) is dramatically upregulated on neutrophils isolated from both human septic patients and in mouse models of sepsis. Compared with the α3ß1 (low) granulocytes, α3ß1 (high) cells from septic animals displayed hyperinflammatory phenotypes. Administration of a α3ß1 blocking peptide and conditional deletion of α3 in granulocytes significantly reduced the number of extravasating neutrophils and improved survival in septic mice. In addition, expression of α3ß1 on neutrophils was associated with Toll-like receptor-induced inflammatory responses and cytokine productions. Thus, our results show that α3ß1 is a novel marker of tissue homing and hyperresponsive neutrophil subtypes in sepsis, and blocking of α3ß1 may represent a new therapeutic approach in sepsis treatment.