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HHV-6B induces IFN-lambda1 responses in cord plasmacytoid dendritic cells through TLR9.

Nordström I, Eriksson K - PLoS ONE (2012)

Bottom Line: Similarly, blockage of TLR9 counteracted HHV-6Bs effects on the Th1/Th2 balance.We conclude that inactivated HHV-6B is a strong inducer of IFN-lambda1 in plasmacytoid DC and that this induction is TLR9-dependent.However, human CD4+ T-cells do not express the IFN-lambda receptor and are refractory to IFN-lambda1 treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

ABSTRACT
Human herpesvirus type 6B (HHV-6B) is a strong inducer of IFN-alpha and has the capacity to promote Th1 responses and block Th2 responses in vitro. In this study we addressed whether inactivated HHV-6B can also induce IFN lambda responses and to what extent interferons alpha and lambda affect Th1/Th2 polarization. We show that inactivated HHV-6B induced IFN-lambda1 (IL-29) but not IFN-lambda2 (IL-28A) responses in plasmacytoid DC and that this induction was mediated through TLR9. We have previously shown that HHV-6B promotes Th1 responses and blocks Th2 responses in both humans and mice. We now show that neutralization of IFN-alpha but not IFN-lambda1 blocked the HHV-6B-induced enhancement of Th1 responses in MLR, but did not affect the HHV-6-induced dampening of Th2 responses. Similarly, blockage of TLR9 counteracted HHV-6Bs effects on the Th1/Th2 balance. In addition, IFN-alpha but not IFN-lambda1 promoted IFN-gamma production and blocked IL-5 and IL-13 production in purified CD4+ T-cells. The lack of effect of IFN-lambda1 correlated with the absence of the IFN-lambda receptor IL-28Ralfa chain on the cell surface of both resting and activated CD4+ T-cells. We conclude that inactivated HHV-6B is a strong inducer of IFN-lambda1 in plasmacytoid DC and that this induction is TLR9-dependent. However, human CD4+ T-cells do not express the IFN-lambda receptor and are refractory to IFN-lambda1 treatment. The HHV-6B-induced alterations in the Th1/Th2 balance are instead mediated mainly through TLR9 and IFN-alpha.

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Neutralization of IFN-alpha but not IFN-lambda1 blocks the HHV-6B-induced promotion of IFN-gamma responses in cord mixed lymphocyte reactions.Cord blood pDC were incubated with allogeneic cord-blood CD4+ T-cells in the presence or absence of inactivated HHV-6B and neutralizing antibodies to IFN-alpha or IFN-lambda1. Supernatants were collected after 48 h and analyzed for IFN-gamma (A), IL-5 (B) and IL-13 (C) content. Data are expressed as medians and the 25% and 75% percentile (the boxes) with the minimum and maximum responses for n = 9. *  =  p<0.05 using ANOVA with Bonferronís multiple comparison test.
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pone-0038683-g002: Neutralization of IFN-alpha but not IFN-lambda1 blocks the HHV-6B-induced promotion of IFN-gamma responses in cord mixed lymphocyte reactions.Cord blood pDC were incubated with allogeneic cord-blood CD4+ T-cells in the presence or absence of inactivated HHV-6B and neutralizing antibodies to IFN-alpha or IFN-lambda1. Supernatants were collected after 48 h and analyzed for IFN-gamma (A), IL-5 (B) and IL-13 (C) content. Data are expressed as medians and the 25% and 75% percentile (the boxes) with the minimum and maximum responses for n = 9. *  =  p<0.05 using ANOVA with Bonferronís multiple comparison test.

Mentions: We have previously shown that HHV-6B exposure promotes Th1 development and blocks Th2 development both in vitro and in vivo in humans and in mice [15], [16]. To assess whether IFN-alpha or IFN-lambda1 is implicated in the HHV-6B-induced Th1/Th2 shift in vitro, we performed MLR of cord pDC and CD4+ T-cells in the presence or absence of HHV-6B and either a specific inhibitor of TLR9 (G-ODN) or neutralizing antibodies to IFN-alpha or IFN-lambda1. In titration experiments, we found that at 10 ug/ml, both these antibodies neutralized 5000 pg/ml of recombinant IFN-alpha and IFN-lambda1, respectively (not shown). As shown before [15], the CD4+ T-cell production of IFN-gamma was increased while the production of IL-5 and IL-13 was decreased in MLR cultures exposed to HHV-6B (Fig. 2A–C). Neutralizing antibodies to IFN-alpha blocked the HHV-6B-induced IFN-gamma responses while neutralizing antibodies to IFN-lambda1 did not have this effect (Fig. 2A). Addition of G-ODN, a specific blocker of TLR9 signaling, blocked the HHV-6B-induced increase in IFN-gamma production and also the HHV-6-induced dampening of IL-13 responses in these cultures (Fig. 3). Neutralization of IFN-alpha or IFN-lambda1 did however not impact on the HHV-6B-induced dampening of IL-5 and IL-13 responses (Fig. 2B–C).


HHV-6B induces IFN-lambda1 responses in cord plasmacytoid dendritic cells through TLR9.

Nordström I, Eriksson K - PLoS ONE (2012)

Neutralization of IFN-alpha but not IFN-lambda1 blocks the HHV-6B-induced promotion of IFN-gamma responses in cord mixed lymphocyte reactions.Cord blood pDC were incubated with allogeneic cord-blood CD4+ T-cells in the presence or absence of inactivated HHV-6B and neutralizing antibodies to IFN-alpha or IFN-lambda1. Supernatants were collected after 48 h and analyzed for IFN-gamma (A), IL-5 (B) and IL-13 (C) content. Data are expressed as medians and the 25% and 75% percentile (the boxes) with the minimum and maximum responses for n = 9. *  =  p<0.05 using ANOVA with Bonferronís multiple comparison test.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368904&req=5

pone-0038683-g002: Neutralization of IFN-alpha but not IFN-lambda1 blocks the HHV-6B-induced promotion of IFN-gamma responses in cord mixed lymphocyte reactions.Cord blood pDC were incubated with allogeneic cord-blood CD4+ T-cells in the presence or absence of inactivated HHV-6B and neutralizing antibodies to IFN-alpha or IFN-lambda1. Supernatants were collected after 48 h and analyzed for IFN-gamma (A), IL-5 (B) and IL-13 (C) content. Data are expressed as medians and the 25% and 75% percentile (the boxes) with the minimum and maximum responses for n = 9. *  =  p<0.05 using ANOVA with Bonferronís multiple comparison test.
Mentions: We have previously shown that HHV-6B exposure promotes Th1 development and blocks Th2 development both in vitro and in vivo in humans and in mice [15], [16]. To assess whether IFN-alpha or IFN-lambda1 is implicated in the HHV-6B-induced Th1/Th2 shift in vitro, we performed MLR of cord pDC and CD4+ T-cells in the presence or absence of HHV-6B and either a specific inhibitor of TLR9 (G-ODN) or neutralizing antibodies to IFN-alpha or IFN-lambda1. In titration experiments, we found that at 10 ug/ml, both these antibodies neutralized 5000 pg/ml of recombinant IFN-alpha and IFN-lambda1, respectively (not shown). As shown before [15], the CD4+ T-cell production of IFN-gamma was increased while the production of IL-5 and IL-13 was decreased in MLR cultures exposed to HHV-6B (Fig. 2A–C). Neutralizing antibodies to IFN-alpha blocked the HHV-6B-induced IFN-gamma responses while neutralizing antibodies to IFN-lambda1 did not have this effect (Fig. 2A). Addition of G-ODN, a specific blocker of TLR9 signaling, blocked the HHV-6B-induced increase in IFN-gamma production and also the HHV-6-induced dampening of IL-13 responses in these cultures (Fig. 3). Neutralization of IFN-alpha or IFN-lambda1 did however not impact on the HHV-6B-induced dampening of IL-5 and IL-13 responses (Fig. 2B–C).

Bottom Line: Similarly, blockage of TLR9 counteracted HHV-6Bs effects on the Th1/Th2 balance.We conclude that inactivated HHV-6B is a strong inducer of IFN-lambda1 in plasmacytoid DC and that this induction is TLR9-dependent.However, human CD4+ T-cells do not express the IFN-lambda receptor and are refractory to IFN-lambda1 treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

ABSTRACT
Human herpesvirus type 6B (HHV-6B) is a strong inducer of IFN-alpha and has the capacity to promote Th1 responses and block Th2 responses in vitro. In this study we addressed whether inactivated HHV-6B can also induce IFN lambda responses and to what extent interferons alpha and lambda affect Th1/Th2 polarization. We show that inactivated HHV-6B induced IFN-lambda1 (IL-29) but not IFN-lambda2 (IL-28A) responses in plasmacytoid DC and that this induction was mediated through TLR9. We have previously shown that HHV-6B promotes Th1 responses and blocks Th2 responses in both humans and mice. We now show that neutralization of IFN-alpha but not IFN-lambda1 blocked the HHV-6B-induced enhancement of Th1 responses in MLR, but did not affect the HHV-6-induced dampening of Th2 responses. Similarly, blockage of TLR9 counteracted HHV-6Bs effects on the Th1/Th2 balance. In addition, IFN-alpha but not IFN-lambda1 promoted IFN-gamma production and blocked IL-5 and IL-13 production in purified CD4+ T-cells. The lack of effect of IFN-lambda1 correlated with the absence of the IFN-lambda receptor IL-28Ralfa chain on the cell surface of both resting and activated CD4+ T-cells. We conclude that inactivated HHV-6B is a strong inducer of IFN-lambda1 in plasmacytoid DC and that this induction is TLR9-dependent. However, human CD4+ T-cells do not express the IFN-lambda receptor and are refractory to IFN-lambda1 treatment. The HHV-6B-induced alterations in the Th1/Th2 balance are instead mediated mainly through TLR9 and IFN-alpha.

Show MeSH
Related in: MedlinePlus