Metabolic, humoral, and cellular responses in adult volunteers immunized with the genetically inactivated pertussis toxin mutant PT-9K/129G.

We have recently shown that the binding subunit of pertussis toxin (PTX-B) inhibits the entry and replication of macrophage-tropic (R5) HIV-1 strains in activated primary T lymphocytes. Furthermore, PTX-B suppressed the replication of T cell-tropic (X4) viruses at a postentry level in the same cells. In this study we demonstrate that PTX-B profoundly impairs entry and replication of the HIV-1ADA (R5), as well as of HIV pseudotyped with either murine leukemia virus or vesicular stomatitis virus envelopes, in primary monocyte-derived macrophages. In addition, PTX-B strongly inhibited X4 HIV-1 replication in U937 promonocytic cells and virus expression in the U937-derived chronically infected U1 cell line stimulated with cytokines such as TNF-α and IL-6. Of interest, TNF-α-mediated activation of the cellular transcription factor NF-κB was unaffected by PTX-B. Therefore, PTX-B may represent a novel and potent inhibitor of HIV-1 replication to be tested for efficacy in infected individuals. In support of this proposition, a genetically modified mutant of PTX (PT-9K/129G), which is safely administered for prevention of Bordetella pertussis infection, showed an in vitro anti-HIV profile superimposable to that of PTX-B.

Section: Discussionmentioning

confidence: 68%

The Binding Subunit of Pertussis Toxin Inhibits HIV Replication in Human Macrophages and Virus Expression in Chronically Infected Promonocytic U1 Cells

Alfano¹,

Vallanti²,

Biswas³

et al. 2001

“…Th17 cytokine responses have been also implicated in vaccine-induced immunity against B. pertussis (46). Our data foster the adjuvant usage of dPT which has lost the undesired toxic activity of its enzymatic moiety, as already demonstrated by its safe use in clinical setting as vaccine Ag (12)(13)(14)(15)(16), and promote the dPT use as adjuvant in human trials. However, considering that dPT used in vaccines was treated with low concentration of Formaldehyde (0,06%), further studies are required, in particular to evaluate whether dPT can be used in humans without Formaldehyde inactivation, or, in alternative, whether this treatment affects the capacity of dPT to modulate DC activities here depicted.…”

Section: Discussionmentioning

confidence: 95%

Genetically Detoxified Pertussis Toxin Induces Th1/Th17 Immune Response through MAPKs and IL-10-Dependent Mechanisms

Nasso

Fedele

Spensieri

et al. 2009

Genetically detoxified pertussis toxin (dPT) maintains the protein structure and the immunological properties, but not the enzymatic activity. In search of an adjuvant able to direct polarization of T cells to induce/potentiate protective immune response to a variety of infectious disease, we investigated the role played by dPT on human dendritic cell-driven Th polarization and analyzed the intracellular signaling events. To reach these aims, we used a highly purified dPT preparation devoid of contamination and monocyte-derived dendritic cells, a well-characterized model to study ex vivo the polarization of the immune responses. First, we analyzed dPT-induced monocyte-derived dendritic cell maturation, longevity, and cytokine production and, in a second step, we analyzed TLR4/2 engagement by dPT, the connected signaling events, and their relevance to the skewing of Th cell polarization. These approaches allowed us to clarify some of the mechanisms that are responsible for dPT-driven regulation of T cell polarization. We demonstrated that dPT acts utilizing TLR4/TLR2 engagement, being the signaling induced by the former stronger. dPT, through a crucial role played by MAPK and IL-10, favors the expansion of the Th1/Th17 immunity. Indirect evidences indicated that dPT-induced Th17 expansion is counterregulated by the PI3K pathway. For its properties and being already used in humans as vaccine Ag in pertussis, dPT may represents a valid candidate adjuvant to foster immune protective response in vaccines against infectious diseases where Th1/Th17 are mediating host immunity.

“…Biotinylated rabbit anti-Tat IgG was obtained from DBA. PTX-B was purchased from Calbiochem, whereas the modified holotoxin PTX, PT-9K/129G, was a gift from Dr. R. Rappuoli (Chiron Spa, Siena, Italy); both were used at 1 nM (34,38).…”

Section: Mabs and Reagentsmentioning

confidence: 99%

Pertussis Toxin (PTX) B Subunit and the Nontoxic PTX Mutant PT9K/129G Inhibit Tat-Induced TGF-β Production by NK Cells and TGF-β-Mediated NK Cell Apoptosis

Zocchi

Contini

Alfano

et al. 2005

We show that the pertussis toxin B oligomer (PTX-B), and the PTX mutant PT9K/129G, which is safely administered in vivo, inhibit both transcription and secretion of TGF-β elicited by HIV-1 Tat in NK cells. Tat-induced TGF-β mRNA synthesis is also blocked by the ERK1 inhibitor PD98059, suggesting that ERK1 is needed for TGF-β production. Moreover, Tat strongly activates the c-Jun component of the multimolecular complex AP-1, whereas TGF-β triggers c-Fos and c-Jun. Of note, treatment of NK cells with PTX-B or PT9K/129G inhibits Tat- and TGF-β-induced activation of AP-1. TGF-β enhances starvation-induced NK cell apoptosis, significantly reduces transcription of the antiapoptotic protein Bcl-2, and inhibits Akt phosphorylation induced by oligomerization of the triggering NK cell receptor NKG2D. All these TGF-β-mediated effects are prevented by PTX-B or PT9K/129G through a PI3K-dependent mechanism, as demonstrated by use of the specific PI3K inhibitor, LY294002. Finally, PTX-B and PT9K/129G up-regulate Bcl-xL, the isoform of Bcl-x that protects cells from starvation-induced apoptosis. It is of note that in NK cells from patients with early HIV-1 infection, mRNA expression of Bcl-2 and Bcl-xL was consistently lower than that in healthy donors; interestingly, TGF-β and Tat were detected in the sera of these patients. Together, these data suggest that Tat-induced TGF-β production and the consequent NK cell failure, possibly occurring during early HIV-1 infection, may be regulated by PTX-B and PT9K/129G.