Release into the supernatant was measured by ELISA. Data is presented as percentage of CpG ODN-induced IFNA1 secretion. (B) In the same experiment, enriched pDCs (white bars) were compared to enriched pDCs seeded into the upper compartment of a two-chamber transwell system containing PBMCs in the lower compartment (pDC:PBMC ratio 1:10, hatched bars). Cells were stimulated with PBS (vehicle), CpG ODN 2336 (1.25 mg/ml) or CpG ODN in the presence of epinephrine (1026 mol/l). After 24 hours, IFNA1 release into the supernatant was measured by ELISA. Data is presented as percentage of CpG ODN-induced IFNA1 secretion. (C) Absolute IFNA1 levels of corresponding conditions in (A). CpG = CpG ODN 2336; epi = epinephrine. * p,0.05; *** p,0.005; statistical comparisons are indicated by brackets. doi:10.1371/journal.pone.0065024.gIncubation with epinephrine for 24 hours did not downregulate the expression of TLR9 compared to control conditions, as assessed by quantitative real-time PCR (data not shown).ADRB2 stimulation attenuates NK cell mediated tumor cell lysis by repression of IFNA1 releaseThe lytic activity of NK cells is greatly enhanced in the presence of IFNA1. We examined the in vitro lysis of K562 cells (immortalized myelogenous tumor cell line) by NK cells after priming with conditioned cell supernatant from PBMCs being previously stimulated with CpG ODN 2336 in the presence or absence of epinephrine. The lytic activity of NK cells was measured by detecting LDH in the supernatant, which was released from K562 cells upon lysis (Fig. 5A). When NK cells were primed with IFNA1-containing supernatant from PBMCs being stimulated with CpG alone, their lytic activity was almost doubled compared to the use of supernatant from PBS-stimulated PBMCs (Fig. 5B). Suppression of TLR9mediated IFNA1 Title Loaded From File secretion by simultaneous adrenoceptor stimulation reduced this enhancement significantly. This correlates with the reduction of IFNA1 secretion from PBMCs by epinephrine.DiscussionpDCs selectively Title Loaded From File express TLR7 and TLR9 and within human immune cells, IFNA1 formation is limited to pDCs. Therefore, within human PBMCs, TLR9 ligand-induced (i.e., CpG ODNinduced) IFNA1 secretion is mediated by stimulation of TLR9 on pDCs. For the first time, we provide detailed insight into epinephrine-mediated modulation 23148522 of TLR9 signaling on these cells showing that epinephrine inhibits TLR9-induced IFNA1 release from PBMCs. We also show that epinephrine suppresses TLR4-induced TNF release from primary human PBMCs. Pharmacologic studies utilizing specific adrenoceptor agonists and antagonists revealed that both effects ?suppression of TLR4mediated TNF release and suppression of TLR9-mediated IFNA1 release ?were mediated by ADRB2. ADRB2-mediated IFNA1 suppression was lost in highly purified pDCs. Using flowcytometric single cell analysis, ADRB2 expression was confirmed for monocytes, but not for pDCs within PBMCs. In agreement with this observation, ADRB2-mediated modulation of TLR9 signaling in pDCs required the presence of other PBMC subsets as evidenced by add-back experiments. Modulation of TLR9dependent pDC activation by PBMCs did not require cell-cell contact, as demonstrated by transwell experiments. Lastly, we provide evidence for possible down-stream effects of adrenoceptormediated suppression of pDC function showing suppression of IFNA1-dependent increased tumor cell lysis by epinephrine. Our study adds to previous evidence from others [20] that adrenoceptor signaling supp.Release into the supernatant was measured by ELISA. Data is presented as percentage of CpG ODN-induced IFNA1 secretion. (B) In the same experiment, enriched pDCs (white bars) were compared to enriched pDCs seeded into the upper compartment of a two-chamber transwell system containing PBMCs in the lower compartment (pDC:PBMC ratio 1:10, hatched bars). Cells were stimulated with PBS (vehicle), CpG ODN 2336 (1.25 mg/ml) or CpG ODN in the presence of epinephrine (1026 mol/l). After 24 hours, IFNA1 release into the supernatant was measured by ELISA. Data is presented as percentage of CpG ODN-induced IFNA1 secretion. (C) Absolute IFNA1 levels of corresponding conditions in (A). CpG = CpG ODN 2336; epi = epinephrine. * p,0.05; *** p,0.005; statistical comparisons are indicated by brackets. doi:10.1371/journal.pone.0065024.gIncubation with epinephrine for 24 hours did not downregulate the expression of TLR9 compared to control conditions, as assessed by quantitative real-time PCR (data not shown).ADRB2 stimulation attenuates NK cell mediated tumor cell lysis by repression of IFNA1 releaseThe lytic activity of NK cells is greatly enhanced in the presence of IFNA1. We examined the in vitro lysis of K562 cells (immortalized myelogenous tumor cell line) by NK cells after priming with conditioned cell supernatant from PBMCs being previously stimulated with CpG ODN 2336 in the presence or absence of epinephrine. The lytic activity of NK cells was measured by detecting LDH in the supernatant, which was released from K562 cells upon lysis (Fig. 5A). When NK cells were primed with IFNA1-containing supernatant from PBMCs being stimulated with CpG alone, their lytic activity was almost doubled compared to the use of supernatant from PBS-stimulated PBMCs (Fig. 5B). Suppression of TLR9mediated IFNA1 secretion by simultaneous adrenoceptor stimulation reduced this enhancement significantly. This correlates with the reduction of IFNA1 secretion from PBMCs by epinephrine.DiscussionpDCs selectively express TLR7 and TLR9 and within human immune cells, IFNA1 formation is limited to pDCs. Therefore, within human PBMCs, TLR9 ligand-induced (i.e., CpG ODNinduced) IFNA1 secretion is mediated by stimulation of TLR9 on pDCs. For the first time, we provide detailed insight into epinephrine-mediated modulation 23148522 of TLR9 signaling on these cells showing that epinephrine inhibits TLR9-induced IFNA1 release from PBMCs. We also show that epinephrine suppresses TLR4-induced TNF release from primary human PBMCs. Pharmacologic studies utilizing specific adrenoceptor agonists and antagonists revealed that both effects ?suppression of TLR4mediated TNF release and suppression of TLR9-mediated IFNA1 release ?were mediated by ADRB2. ADRB2-mediated IFNA1 suppression was lost in highly purified pDCs. Using flowcytometric single cell analysis, ADRB2 expression was confirmed for monocytes, but not for pDCs within PBMCs. In agreement with this observation, ADRB2-mediated modulation of TLR9 signaling in pDCs required the presence of other PBMC subsets as evidenced by add-back experiments. Modulation of TLR9dependent pDC activation by PBMCs did not require cell-cell contact, as demonstrated by transwell experiments. Lastly, we provide evidence for possible down-stream effects of adrenoceptormediated suppression of pDC function showing suppression of IFNA1-dependent increased tumor cell lysis by epinephrine. Our study adds to previous evidence from others [20] that adrenoceptor signaling supp.
