Lipopeptides rather than lipopolysaccharide favor the development of dendritic cell dysfunction similar to polymicrobial sepsis in mice

We investigated whether the dysfunction of dendritic cells (DC) that develops during polymicrobial sepsis is mimicked by systemic administration of the Toll-like receptor (TLR) 4 agonist lipopolysaccharide (LPS) or of the TLR2 agonist Pam3-Cys-Ser-Lys4 (P3CSK4). BALB/c mice underwent cecal ligation and puncture (CLP) or sham operation or received a single i.p. injection of LPS (30 mg/kg body weight), P3CSK4 (10 mg/kg body weight), or saline as control. Purified splenic DC and in-vitro-generated DC from bone marrow were analyzed in terms of surface marker expression, cytokine secretion, and antigen-specific T-cell activation in vivo. Splenic DC were suppressed in IL-12 secretion 12 h after LPS and P3CSK4 administration but released increased levels of IL-12 4 days after TLR agonist application, unlike DC from CLP mice. Polymicrobial sepsis and TLR agonists caused a loss of DC in the spleen but led to the expansion of diverse DC subsets. DC that differentiated from bone marrow after P3CSK4 but not after LPS application resembled DC from CLP mice regarding cytokine secretion and impaired Th1-cell polarization. The development of DC dysfunction during sepsis is at least partly mimicked by TLR2 agonists rather than TLR4 agonists.