• Erica L Martin, Danielle G Souza, Caio T Fagundes, Flavio A Amaral, Barbara Assenzio, Valeria Puntorieri, Lorenzo Del Sorbo, Vito Fanelli, Martino Bosco, Luisa Delsedime, Jose F Pinho, Virginia S Lemos, Fabricio O Souto, Jose C Alves-Filho, Fernando Q Cunha, Arthur S Slutsky, Thomas Ruckle, Emilio Hirsch, Mauro M Teixeira, and V Marco Ranieri.
• Department of Anesthesiology and Critical Care, University of Turin, Ospedale S. Giovanni Battista-Molinette, Turin, Italy. ericaleanne.martin@unito.it
• Am. J. Respir. Crit. Care Med. 2010 Sep 15; 182 (6): 762-73.

RationaleSepsis is a leading cause of death in the intensive care unit, characterized by a systemic inflammatory response (SIRS) and bacterial infection, which can often induce multiorgan damage and failure. Leukocyte recruitment, required to limit bacterial spread, depends on phosphoinositide-3 kinase γ (PI3Kγ) signaling in vitro; however, the role of this enzyme in polymicrobial sepsis has remained unclear.ObjectivesThis study aimed to determine the specific role of the kinase activity of PI3Kγ in the pathogenesis of sepsis and multiorgan damage.MethodsPI3Kγ wild-type, knockout, and kinase-dead mice were exposed to cecal ligation and perforation-induced sepsis and assessed for survival; pulmonary, hepatic, and cardiovascular damage; coagulation derangements; systemic inflammation; bacterial spread; and neutrophil recruitment. Additionally, wild-type mice were treated either before or after the onset of sepsis with a PI3Kγ inhibitor and assessed for survival, neutrophil recruitment, and bacterial spread.Measurements And Main ResultsBoth genetic and pharmaceutical PI3Kγ kinase inhibition significantly improved survival, reduced multiorgan damage, and limited bacterial decompartmentalization, while modestly affecting SIRS. Protection resulted from both neutrophil-independent mechanisms, involving improved cardiovascular function, and neutrophil-dependent mechanisms, through reduced susceptibility to neutrophil migration failure during severe sepsis by maintaining neutrophil surface expression of the chemokine receptor, CXCR2. Furthermore, PI3Kγ pharmacological inhibition significantly decreased mortality and improved neutrophil migration and bacterial control, even when administered during established septic shock.ConclusionsThis study establishes PI3Kγ as a key molecule in the pathogenesis of septic infection and the transition from SIRS to organ damage and identifies it as a novel possible therapeutic target.

29 keywords...

hide…