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HIV-1 gp120 impairs the induction of B cell responses by TLR9-activated plasmacytoid dendritic cells.

ABSTRACT: Plasmacytoid dendritic cells (pDCs) play a central role in innate and adaptive immune responses to viral infections, including HIV type 1 (HIV-1). pDCs produce substantial quantities of type I IFN and proinflammatory cytokines upon stimulation via TLRs, specifically TLR7 or TLR9. The HIV-1 envelope glycoproteins, exemplified by the gp120 monomer, are the focus of vaccines aimed at inducing B cell responses. We have studied how the interactions of gp120 with various receptors on human pDCs affect the activation of these cells via TLR9 and their subsequent ability to stimulate B cells. We observed that IFN-? production by pDCs in response to TLR9, but not TLR7, stimulation was reduced by exposure to gp120. Specifically, gp120 inhibited the CpG-induced maturation of pDCs and their expression of TNF-?, IL-6, TLR9, IFN regulatory factor 7, and BAFF. Receptor-blocking and cross-linking studies showed that these inhibitory effects of gp120 were mediated by interactions with CD4 and mannose-binding C-type lectin receptors, but not with the chemokine receptors CCR5 and CXCR4. Of note is that gp120 inhibited the activation of B cells by TLR9-stimulated pDCs. Taken together, our data show that HIV-1 gp120 impairs pDC functions, including activation of B cell responses, and imply that TLR9 ligands may not be good adjuvants to use in combination with envelope glycoprotein vaccines.

SUBMITTER: Chung NP

PROVIDER: S-EPMC3504132 | biostudies-other | 2012 Dec

REPOSITORIES: biostudies-other

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HIV-1 gp120 impairs the induction of B cell responses by TLR9-activated plasmacytoid dendritic cells.

Chung Nancy P Y NP Matthews Katie K Klasse Per Johan PJ Sanders Rogier W RW Moore John P JP

Journal of immunology (Baltimore, Md. : 1950) 20121024 11

Plasmacytoid dendritic cells (pDCs) play a central role in innate and adaptive immune responses to viral infections, including HIV type 1 (HIV-1). pDCs produce substantial quantities of type I IFN and proinflammatory cytokines upon stimulation via TLRs, specifically TLR7 or TLR9. The HIV-1 envelope glycoproteins, exemplified by the gp120 monomer, are the focus of vaccines aimed at inducing B cell responses. We have studied how the interactions of gp120 with various receptors on human pDCs affect ...[more]

PMID: 23100517

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Project description:BACKGROUND:Atopy and viral respiratory tract infections synergistically promote asthma exacerbations. IgE cross-linking inhibits critical virus-induced IFN-? responses of plasmacytoid dendritic cells (pDCs), which can be deficient in patients with allergic asthma. OBJECTIVE:We sought to determine whether reducing IgE levels in vivo with omalizumab treatment increases pDC antiviral IFN-? responses in inner-city children with asthma. METHODS:PBMCs and pDCs isolated from children with exacerbation-prone asthma before and during omalizumab treatment were stimulated ex vivo with rhinovirus and influenza in the presence or absence of IgE cross-linking. IFN-? levels were measured in supernatants, and mRNA expression of IFN-? pathway genes was determined by using quantitative RT-PCR (qRT-PCR) in cell pellets. Fc?RI? protein levels and mRNA expression were measured in unstimulated cells by using flow cytometry and qRT-PCR, respectively. Changes in these outcomes and associations with clinical outcomes were analyzed, and statistical modeling was used to identify risk factors for asthma exacerbations. RESULTS:Omalizumab treatment increased rhinovirus- and influenza-induced PBMC and rhinovirus-induced pDC IFN-? responses in the presence of IgE cross-linking and reduced pDC surface Fc?RI? expression. Omalizumab-induced reductions in pDC Fc?RI? levels were significantly associated with a lower asthma exacerbation rate during the outcome period and correlated with increases in PBMC IFN-? responses. PBMC Fc?RI? mRNA expression measured on study entry significantly improved an existing model of exacerbation prediction. CONCLUSIONS:These findings indicate that omalizumab treatment augments pDC IFN-? responses and attenuates pDC Fc?RI? protein expression and provide evidence that these effects are related. These results support a potential mechanism underlying clinical observations that allergic sensitization is associated with increased susceptibility to virus-induced asthma exacerbations.

Dataset Information

HIV-1 gp120 impairs the induction of B cell responses by TLR9-activated plasmacytoid dendritic cells.

Publications

HIV-1 gp120 impairs the induction of B cell responses by TLR9-activated plasmacytoid dendritic cells.

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