Bordetella pertussis Commits Human Dendritic Cells to Promote a Th1/Th17 Response through the Activity of Adenylate Cyclase Toxin and MAPK-Pathways

Abstract

The complex pathology of B. pertussis infection is due to multiple virulence factors having disparate effects on different cell types. We focused our investigation on the ability of B. pertussis to modulate host immunity, in particular on the role played by adenylate cyclase toxin (CyaA), an important virulence factor of B. pertussis. As a tool, we used human monocyte derived dendritic cells (MDDC), an ex vivo model useful for the evaluation of the regulatory potential of DC on T cell immune responses. The work compared MDDC functions after encounter with wild-type B. pertussis (BpWT) or a mutant lacking CyaA (BpCyaA−), or the BpCyaA− strain supplemented with either the fully functional CyaA or a derivative, CyaA*, lacking adenylate cyclase activity. As a first step, MDDC maturation, cytokine production, and modulation of T helper cell polarization were evaluated. As a second step, engagement of Toll-like receptors (TLR) 2 and TLR4 by B. pertussis and the signaling events connected to this were analyzed. These approaches allowed us to demonstrate that CyaA expressed by B. pertussis strongly interferes with DC functions, by reducing the expression of phenotypic markers and immunomodulatory cytokines, and blocking IL-12p70 production. B. pertussis-treated MDDC promoted a mixed Th1/Th17 polarization, and the activity of CyaA altered the Th1/Th17 balance, enhancing Th17 and limiting Th1 expansion. We also demonstrated that Th1 effectors are induced by B. pertussis-MDDC in the absence of IL-12p70 through an ERK1/2 dependent mechanism, and that p38 MAPK is essential for MDDC-driven Th17 expansion. The data suggest that CyaA mediates an escape strategy for the bacterium, since it reduces Th1 immunity and increases Th17 responses thought to be responsible, when the response is exacerbated, for enhanced lung inflammation and injury.

Attenuated Bordetella pertussis Vaccine Candidate BPZE1 Promotes Human Dendritic Cell CCL21-Induced Migration and Drives a Th1/Th17 Response

“…Overall, BPZE1 and its virulent parent strain BPSM behave similarly as far as the capacity to strongly induce allogeneic T cell stimulation and polarization of Th cells are concerned, retaining the same properties already shown in our previous study using B. pertussis strain 18323 (11).…”

“…We used a well-established model of MDDC challenge with B. pertussis to analyze several aspects of BPZE1-driven immune responses in humans (9)(10)(11). In this study, we show that BPZE1, despite being strongly attenuated, maintains the capacity to promote MDDC maturation and, similar to BPSM, is able to protect cells from apoptosis.…”

“…Human monocytes were purified as described (10,11) from peripheral blood of healthy blood donors (courtesy of Dr. Girelli, "Centro Trasfusionale Policlinico Umberto I," University La Sapienza, Rome, Italy) and cultured in RPMI 1640 medium (Life Technologies Invitrogen, Paisley, U.K.), supplemented with heat-inactivated 10% LPS-screened FCS, 1 mM sodium pyruvate, 0.1 mM nonessential amino acids, 2 mM L-glutamine, 25 mM HEPES, 100 U/ml penicillin, 100 mg/ml streptomycin, all from Hyclone Laboratories (South Logan, UT), and 0.05 mM 2-mercaptoethanol (Sigma) (hereafter defined as complete medium) in the presence of GM-CSF (25 ng/ml) and IL-4 (25 ng/ml). After 6 d, immature MDDCs were washed and analyzed by cytofluorometry for the expression of surface markers CD1a, CD14, CD83, and CD38.…”

“…5). Given the cytokine profile induced by BPZE1 in MDDCs, we analyzed their capacity to polarize purified T lymphocytes and, in particular, the possibility of Th1/Th17 induction, already described in human (11) and mouse models (16)(17)(18) and considered to contribute to protection induced by whole-cell pertussis vaccination (18). We assessed the capacity to induce polarization in naive CD45RA + T cells as well as in already primed CD3 + T cells.…”

IL-32γ Induces the Maturation of Dendritic Cells with Th1- and Th17-Polarizing Ability through Enhanced IL-12 and IL-6 Production

“…Indeed, the release of IL-12 was also shown to be upregulated in IL-32g-stimulated DCs. The simultaneous stimulation of Th1 and Th17 type responses has also been described previously by other investigators (35)(36)(37). Both the Th1 and Th17 subsets promote cellular immune function and can induce inflammation and autoimmune diseases, such as inflammatory bowel diseases and collagen-induced arthritis (17, 20, 38, 39).…”