The adenylate cyclase toxin-hemolysin (CyaA, ACT, or AC-Hly) of Bordetella pertussis targets phagocytic cells expressing the complement receptor 3 (CR3, Mac-1, αMβ2 integrin, or CD11b/CD18). CyaA delivers into cells an N-terminal adenylyl cyclase (AC) enzyme domain that is activated by cytosolic calmodulin and catalyzes unregulated conversion of cellular ATP into cyclic AMP (cAMP), a key second messenger subverting bactericidal activities of phagocytes. In parallel, the hemolysin (Hly) moiety of CyaA forms cation-selective hemolytic pores that permeabilize target cell membranes. We constructed the first B. pertussis mutant secreting a CyaA toxin having an intact capacity to deliver the AC enzyme into CD11b-expressing (CD11b(+)) host phagocytes but impaired in formation of cell-permeabilizing pores and defective in cAMP elevation in CD11b(-) cells. The nonhemolytic AC(+) Hly(-) bacteria inhibited the antigen-presenting capacities of coincubated mouse dendritic cells in vitro and skewed their Toll-like receptor (TLR)-triggered maturation toward a tolerogenic phenotype. The AC(+) Hly(-) mutant also infected mouse lungs as efficiently as the parental AC(+) Hly(+) strain. Hence, elevation of cAMP in CD11b(-) cells and/or the pore-forming capacity of CyaA were not required for infection of mouse airways. The latter activities were, however, involved in bacterial penetration across the epithelial layer, enhanced neutrophil influx into lung parenchyma during sublethal infections, and the exacerbated lung pathology and lethality of B. pertussis infections at higher inoculation doses (>10(7) CFU/mouse). The pore-forming activity of CyaA further synergized with the cAMP-elevating activity in downregulation of major histocompatibility complex class II (MHC-II) molecules on infiltrating myeloid cells, likely contributing to immune subversion of host defenses by the whooping cough agent.

• MeSH
• adenylátcyklasový toxin metabolismus   MeSH
• AMP cyklický metabolismus   MeSH
• antigeny CD11b metabolismus   MeSH
• Bordetella pertussis patogenita   MeSH
• buněčná membrána metabolismus   MeSH
• dendritické buňky imunologie   MeSH
• fagocyty imunologie   MeSH
• hemolyziny metabolismus   MeSH
• makrofágový antigen 1 metabolismus   MeSH
• myši inbrední BALB C MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• pertuse mikrobiologie   MeSH
• plíce mikrobiologie   patologie   MeSH
• T-lymfocyty imunologie   MeSH
• virulence MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The adenylate cyclase toxin-hemolysin (CyaA) of Bordetella pertussis is a bi-functional leukotoxin. It penetrates myeloid phagocytes expressing the complement receptor 3 and delivers into their cytosol its N-terminal adenylate cyclase enzyme domain (~400 residues). In parallel, ~1300 residue-long RTX hemolysin moiety of CyaA forms cation-selective pores and permeabilizes target cell membrane for efflux of cytosolic potassium ions. The non-enzymatic CyaA-AC(-) toxoid, has repeatedly been successfully exploited as an antigen delivery tool for stimulation of adaptive T-cell immune responses. We show that the pore-forming activity confers on the CyaA-AC(-) toxoid a capacity to trigger Toll-like receptor and inflammasome signaling-independent maturation of CD11b-expressing dendritic cells (DC). The DC maturation-inducing potency of mutant toxoid variants in vitro reflected their specifically enhanced or reduced pore-forming activity and K(+) efflux. The toxoid-induced in vitro phenotypic maturation of DC involved the activity of mitogen activated protein kinases p38 and JNK and comprised increased expression of maturation markers, interleukin 6, chemokines KC and LIX and granulocyte-colony-stimulating factor secretion, prostaglandin E2 production and enhancement of chemotactic migration of DC. Moreover, i.v. injected toxoids induced maturation of splenic DC in function of their cell-permeabilizing capacity. Similarly, the capacity of DC to stimulate CD8(+) and CD4(+) T-cell responses in vitro and in vivo was dependent on the pore-forming activity of CyaA-AC(-). This reveals a novel self-adjuvanting capacity of the CyaA-AC(-) toxoid that is currently under clinical evaluation as a tool for delivery of immunotherapeutic anti-cancer CD8(+) T-cell vaccines into DC.

• MeSH
• adenylátcyklasový toxin genetika   imunologie   MeSH
• adjuvancia imunologická genetika   MeSH
• aktivace lymfocytů * MeSH
• buněčná diferenciace MeSH
• CD4-pozitivní T-lymfocyty imunologie   MeSH
• CD8-pozitivní T-lymfocyty imunologie   MeSH
• cytokiny metabolismus   MeSH
• cytotoxické proteiny tvořící póry genetika   imunologie   MeSH
• dendritické buňky imunologie   mikrobiologie   MeSH
• iontový transport MeSH
• kultivované buňky MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• permeabilita buněčné membrány MeSH
• proteinové domény genetika   imunologie   MeSH
• protinádorové vakcíny imunologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Adenylate cyclase toxin (CyaA) is a key virulence factor of the whooping cough agent Bordetella pertussis. The toxin targets CD11b-expressing phagocytes and delivers into their cytosol an adenylyl cyclase (AC) enzyme that subverts cellular signaling by increasing cAMP levels. In the present study, we analyzed the modulatory effects of CyaA on adhesive, migratory and antigen presenting properties of Toll-like receptor (TLR)-activated murine and human dendritic cells (DCs). cAMP signaling of CyaA enhanced TLR-induced dissolution of cell adhesive contacts and migration of DCs towards the lymph node-homing chemokines CCL19 and CCL21 in vitro. Moreover, we examined in detail the capacity of toxin-treated DCs to induce CD4(+) and CD8(+) T cell responses. Exposure to CyaA decreased the capacity of LPS-stimulated DCs to present soluble protein antigen to CD4+ T cells independently of modulation of co-stimulatory molecules and cytokine production, and enhanced their capacity to promote CD4(+)CD25(+)Foxp3(+) T regulatory cells in vitro. In addition, CyaA decreased the capacity of LPS-stimulated DCs to induce CD8(+) T cell proliferation and limited the induction of IFN-γ producing CD8(+) T cells while enhancing IL-10 and IL-17-production. These results indicate that through activation of cAMP signaling, the CyaA may be mobilizing DCs impaired in T cell stimulatory capacity and arrival of such DCs into draining lymph nodes may than contribute to delay and subversion of host immune responses during B. pertussis infection.

• MeSH
• adenylátcyklasový toxin farmakologie   MeSH
• aktivace lymfocytů účinky léků   MeSH
• Bordetella pertussis chemie   MeSH
• buněčná adheze účinky léků   MeSH
• buněčná smrt účinky léků   MeSH
• CD antigeny metabolismus   MeSH
• CD8-pozitivní T-lymfocyty cytologie   účinky léků   imunologie   MeSH
• dendritické buňky cytologie   účinky léků   imunologie   MeSH
• lidé MeSH
• myši inbrední C57BL MeSH
• pohyb buněk účinky léků   MeSH
• proliferace buněk účinky léků   MeSH
• regulační T-lymfocyty účinky léků   MeSH
• rozpustnost MeSH
• toll-like receptory metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH