Adenylate Cyclase Toxin fromBordetella pertussisSynergizes with Lipopolysaccharide To Promote Innate Interleukin-10 Production and Enhances the Induction of Th2 and Regulatory T Cells

Abstract

Adenylate cyclase toxin (CyaA) from Bordetella pertussis can subvert host immune responses allowing bacterial colonization. Here we have examined its adjuvant and immunomodulatory properties and the possible contribution of lipopolysaccharide (LPS), known to be present in purified CyaA preparations. CyaA enhanced antigen-specific interleukin-5 (IL-5) and IL-10 production and immunoglobulin G1 antibodies to coadministered antigen in vivo. Antigen-specific CD4+-T-cell clones generated from mice immunized with antigen and CyaA had cytokine profiles characteristic of Th2 or type 1 regulatory T (Tr1) cells. Since innate immune cells direct the induction of T-cell subtypes, we examined the influence of CyaA on activation of dendritic cells (DC) and macrophages. CyaA significantly augmented LPS-induced IL-6 and IL-10 and inhibited LPS-driven tumor necrosis factor alpha and IL-12p70 production from bone marrow-derived DC and macrophages. CyaA also enhanced cell surface expression of CD80, CD86, and major histocompatibility class II on immature DC. The stimulatory activity of our CyaA preparation for IL-10 production and CD80, CD86, and major histocompatibility complex class II expression was attenuated following the addition of polymyxin B or with the use of DC from Toll-like receptor (TLR) 4-defective mice. However, treatment of DC with LPS alone at the concentration present in the CyaA preparation (0.2 ng/ml) failed to activate DC in vitro. Our findings demonstrate that activation of innate cells in vitro by CyaA is dependent on a second signal through a TLR and that CyaA can promote Th2/Tr1-cell responses by inhibiting IL-12 and promoting IL-10 production by DC and macrophages

Bordetella pertussis Adenylate Cyclase Toxin Modulates Innate and Adaptive Immune Responses: Distinct Roles for Acylation and Enzymatic Activity in Immunomodulation and Cell Death

“…We and others have previously shown that CyaA of B. pertussis is an effective vaccine adjuvant in vivo, enhancing Ab responses to coadministered Ags (7)(8)(9)(10). Our studies also demonstrated that CyaA promotes Th2 and type 1 regulatory T (Tr1) cell responses to coadministered Ags (9).…”

“…Our studies also demonstrated that CyaA promotes Th2 and type 1 regulatory T (Tr1) cell responses to coadministered Ags (9). Studies with innate immune cells in vitro indicated that these adaptive immune responses were mediated via the modulation of DC and macrophage activation.…”

“…Studies with innate immune cells in vitro indicated that these adaptive immune responses were mediated via the modulation of DC and macrophage activation. Treatment of LPS-stimulated macrophages or murine bone marrowderived DC with CyaA suppressed production of the proinflammatory cytokines and chemokines IL-12p70, TNF-␣, and CCL3 (MIP-1␣) and enhanced IL-10 production (9). Furthermore, CyaA enhanced surface expression of the costimulatory molecule CD80 on immature DC, but decreased expression of LPS-induced ICAM-1 (CD54) and CD40, indicating that CyaA selectively modulates DC activation and maturation.…”

“…The N-terminal His-tagged proteins were purified from inclusion bodies by DEAE-Sepharose and Ni 2ϩ -agarose chromatography (9). LPS was removed from CyaA by dialysis first against Dulbecco's PBS (SigmaAldrich), 1 mM EDTA, 1 M urea, pH 4.6, and then against Dulbecco's PBS, 0.1 mM CaCl 2 , 2 M urea, pH 8.0.…”

“…Results are expressed in cpm. KLH-specific IgG, IgG1, and IgG2a serum titers were determined by ELISA as previously described (9).…”