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NMDA-receptor antagonists block B-cell function but foster IL-10 production in BCR/CD40-activated B cells.

Simma N, Bose T, Kahlfuss S, Mankiewicz J, Lowinus T, Lühder F, Schüler T, Schraven B, Heine M, Bommhardt U - Cell Commun. Signal (2014)

Bottom Line: Mechanistically, these effects were mediated through a blockade of Kv1.3 and KCa3.1 potassium channels and resulted in an attenuated Ca(2+)-flux and activation of Erk1/2, Akt and NFATc1.Non-competitive NMDAR antagonists attenuate BCR and Toll-like receptor 4 (TLR4) B-cell signaling and effector function and can foster IL-10 production.The drugs' additional side effects on B cells should be considered in treatments of neuronal disorders with NMDAR antagonists.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany. Narasimhulu.Simma@st.ovgu.de.

ABSTRACT

Background: B cells are important effectors and regulators of adaptive and innate immune responses, inflammation and autoimmunity, for instance in anti-NMDA-receptor (NMDAR) encephalitis. Thus, pharmacological modulation of B-cell function could be an effective regimen in therapeutic strategies. Since the non-competitive NMDAR antagonist memantine is clinically applied to treat advanced Alzheimer`s disease and ketamine is supposed to improve the course of resistant depression, it is important to know how these drugs affect B-cell function.

Results: Non-competitive NMDAR antagonists impaired B-cell receptor (BCR)- and lipopolysaccharide (LPS)-induced B-cell proliferation, reduced B-cell migration towards the chemokines SDF-1α and CCL21 and downregulated IgM and IgG secretion. Mechanistically, these effects were mediated through a blockade of Kv1.3 and KCa3.1 potassium channels and resulted in an attenuated Ca(2+)-flux and activation of Erk1/2, Akt and NFATc1. Interestingly, NMDAR antagonist treatment increased the frequency of IL-10 producing B cells after BCR/CD40 stimulation.

Conclusions: Non-competitive NMDAR antagonists attenuate BCR and Toll-like receptor 4 (TLR4) B-cell signaling and effector function and can foster IL-10 production. Consequently, NMDAR antagonists may be useful to target B cells in autoimmune diseases or pathological systemic inflammation. The drugs' additional side effects on B cells should be considered in treatments of neuronal disorders with NMDAR antagonists.

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Effects of NMDAR antagonists on B-cell membranepotential and K+channel activity. B cells were activatedwith α-IgM or LPS (10 μg/ml each) for 24–48 h. A) NMDAR antagonists lead to a depolarization of themembrane potential. Activated B cells were analyzed for changes in themembrane potential upon addition of ifenprodil or memantine inconcentrations as indicated. KCl treatment served as a control for cellintegrity. B-D) Ifenprodil and memantineinhibit K+ channel activity. Dose-inhibition curves of B) Kv1.3 and C) KCa3.1 channels in the presence ofifenprodil or memantine were plotted from the recorded maximal transientcurrents. Insets show one particular trace of control and inhibitingcurrent along with the protocol used for measuring B) Kv1.3 and C) KCa3.1 channels. D) Data in the graphs represent the relativeinhibition of Kv1.3- andKCa3.1-mediated currents in the presence of thecompetitive NMDAR antagonist D-APV. All data were calculated from 5–6cells of four experiments and are represented as mean ± SD.
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Fig2: Effects of NMDAR antagonists on B-cell membranepotential and K+channel activity. B cells were activatedwith α-IgM or LPS (10 μg/ml each) for 24–48 h. A) NMDAR antagonists lead to a depolarization of themembrane potential. Activated B cells were analyzed for changes in themembrane potential upon addition of ifenprodil or memantine inconcentrations as indicated. KCl treatment served as a control for cellintegrity. B-D) Ifenprodil and memantineinhibit K+ channel activity. Dose-inhibition curves of B) Kv1.3 and C) KCa3.1 channels in the presence ofifenprodil or memantine were plotted from the recorded maximal transientcurrents. Insets show one particular trace of control and inhibitingcurrent along with the protocol used for measuring B) Kv1.3 and C) KCa3.1 channels. D) Data in the graphs represent the relativeinhibition of Kv1.3- andKCa3.1-mediated currents in the presence of thecompetitive NMDAR antagonist D-APV. All data were calculated from 5–6cells of four experiments and are represented as mean ± SD.

Mentions: We previously reported that protein expression of functional NMDARsin murine T cells is elusive and that NMDAR antagonists inhibitKv1.3 and KCa3.1 channels[53], which are considered aspotent targets for immunosuppression [54,55]. Thesepotassium channels are also expressed on B cells and their inhibition was found todifferentially influence B-cell proliferation after BCR activation or PMA/IOstimulation [56–59]. Since KCa3.1 andKv1.3 channel activities influence membranedepolarization and, thereby, the Ca2+-flux into thecell [60], we first determined thedrugs’ effects on the membrane potential. Ifenprodil (20 μM) and memantine (30 μM)reduced the membrane potential of α-IgM- or LPS-activated B cells from ~ −40 mVto ~ −20 mV and ~ −10 mV, respectively. Addition of KCl served as a positivecontrol for membrane depolarization (Figure 2A). Next, we recorded Kv1.3channel-mediated currents from activated B cells and the dose response curves inthe presence of inhibitors were calculated from maximal transient currentamplitudes. Ifenprodil and memantine markedly reduced Kv1.3channel currents irrespective whether B cells were stimulated with α-IgM or LPS(Figure 2B). IC50and Hill slope values for α-IgM-activated B cells were ~20 μM and ~1.3 forifenprodil and ~40 μM and ~1.8 for memantine. For LPS-treated B cells,IC50 and Hill slope values were ~18 μM and ~1.4 forifenprodil and ~45 μM and ~1.2 for memantine. For B cells stimulated by BCRligation, we additionally recorded KCa3.1 channel-mediatedcurrents (Figure 2C).KCa3.1 currents were not detected in LPS-activated Bcells. IC50 values for ifenprodil and memantine were ~30 μMand ~50 μM and Hill slopes were ~1.4 and ~1.6. However, the competitive NMDARantagonist D-APV, which blocks neuronal NMDARs at the 1 μM range, had no effect onKv1.3 and KCa3.1 channels, even at10-time higher concentrations (300 μM) (Figure 2D). Thus, Kv1.3 andKCa3.1 channels, whose specific blockade abolishes B-cellactivation [56,59], are partially inhibited by thenon-competitive NMDAR antagonists ifenprodil and memantine.Figure 2


NMDA-receptor antagonists block B-cell function but foster IL-10 production in BCR/CD40-activated B cells.

Simma N, Bose T, Kahlfuss S, Mankiewicz J, Lowinus T, Lühder F, Schüler T, Schraven B, Heine M, Bommhardt U - Cell Commun. Signal (2014)

Effects of NMDAR antagonists on B-cell membranepotential and K+channel activity. B cells were activatedwith α-IgM or LPS (10 μg/ml each) for 24–48 h. A) NMDAR antagonists lead to a depolarization of themembrane potential. Activated B cells were analyzed for changes in themembrane potential upon addition of ifenprodil or memantine inconcentrations as indicated. KCl treatment served as a control for cellintegrity. B-D) Ifenprodil and memantineinhibit K+ channel activity. Dose-inhibition curves of B) Kv1.3 and C) KCa3.1 channels in the presence ofifenprodil or memantine were plotted from the recorded maximal transientcurrents. Insets show one particular trace of control and inhibitingcurrent along with the protocol used for measuring B) Kv1.3 and C) KCa3.1 channels. D) Data in the graphs represent the relativeinhibition of Kv1.3- andKCa3.1-mediated currents in the presence of thecompetitive NMDAR antagonist D-APV. All data were calculated from 5–6cells of four experiments and are represented as mean ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Fig2: Effects of NMDAR antagonists on B-cell membranepotential and K+channel activity. B cells were activatedwith α-IgM or LPS (10 μg/ml each) for 24–48 h. A) NMDAR antagonists lead to a depolarization of themembrane potential. Activated B cells were analyzed for changes in themembrane potential upon addition of ifenprodil or memantine inconcentrations as indicated. KCl treatment served as a control for cellintegrity. B-D) Ifenprodil and memantineinhibit K+ channel activity. Dose-inhibition curves of B) Kv1.3 and C) KCa3.1 channels in the presence ofifenprodil or memantine were plotted from the recorded maximal transientcurrents. Insets show one particular trace of control and inhibitingcurrent along with the protocol used for measuring B) Kv1.3 and C) KCa3.1 channels. D) Data in the graphs represent the relativeinhibition of Kv1.3- andKCa3.1-mediated currents in the presence of thecompetitive NMDAR antagonist D-APV. All data were calculated from 5–6cells of four experiments and are represented as mean ± SD.
Mentions: We previously reported that protein expression of functional NMDARsin murine T cells is elusive and that NMDAR antagonists inhibitKv1.3 and KCa3.1 channels[53], which are considered aspotent targets for immunosuppression [54,55]. Thesepotassium channels are also expressed on B cells and their inhibition was found todifferentially influence B-cell proliferation after BCR activation or PMA/IOstimulation [56–59]. Since KCa3.1 andKv1.3 channel activities influence membranedepolarization and, thereby, the Ca2+-flux into thecell [60], we first determined thedrugs’ effects on the membrane potential. Ifenprodil (20 μM) and memantine (30 μM)reduced the membrane potential of α-IgM- or LPS-activated B cells from ~ −40 mVto ~ −20 mV and ~ −10 mV, respectively. Addition of KCl served as a positivecontrol for membrane depolarization (Figure 2A). Next, we recorded Kv1.3channel-mediated currents from activated B cells and the dose response curves inthe presence of inhibitors were calculated from maximal transient currentamplitudes. Ifenprodil and memantine markedly reduced Kv1.3channel currents irrespective whether B cells were stimulated with α-IgM or LPS(Figure 2B). IC50and Hill slope values for α-IgM-activated B cells were ~20 μM and ~1.3 forifenprodil and ~40 μM and ~1.8 for memantine. For LPS-treated B cells,IC50 and Hill slope values were ~18 μM and ~1.4 forifenprodil and ~45 μM and ~1.2 for memantine. For B cells stimulated by BCRligation, we additionally recorded KCa3.1 channel-mediatedcurrents (Figure 2C).KCa3.1 currents were not detected in LPS-activated Bcells. IC50 values for ifenprodil and memantine were ~30 μMand ~50 μM and Hill slopes were ~1.4 and ~1.6. However, the competitive NMDARantagonist D-APV, which blocks neuronal NMDARs at the 1 μM range, had no effect onKv1.3 and KCa3.1 channels, even at10-time higher concentrations (300 μM) (Figure 2D). Thus, Kv1.3 andKCa3.1 channels, whose specific blockade abolishes B-cellactivation [56,59], are partially inhibited by thenon-competitive NMDAR antagonists ifenprodil and memantine.Figure 2

Bottom Line: Mechanistically, these effects were mediated through a blockade of Kv1.3 and KCa3.1 potassium channels and resulted in an attenuated Ca(2+)-flux and activation of Erk1/2, Akt and NFATc1.Non-competitive NMDAR antagonists attenuate BCR and Toll-like receptor 4 (TLR4) B-cell signaling and effector function and can foster IL-10 production.The drugs' additional side effects on B cells should be considered in treatments of neuronal disorders with NMDAR antagonists.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany. Narasimhulu.Simma@st.ovgu.de.

ABSTRACT

Background: B cells are important effectors and regulators of adaptive and innate immune responses, inflammation and autoimmunity, for instance in anti-NMDA-receptor (NMDAR) encephalitis. Thus, pharmacological modulation of B-cell function could be an effective regimen in therapeutic strategies. Since the non-competitive NMDAR antagonist memantine is clinically applied to treat advanced Alzheimer`s disease and ketamine is supposed to improve the course of resistant depression, it is important to know how these drugs affect B-cell function.

Results: Non-competitive NMDAR antagonists impaired B-cell receptor (BCR)- and lipopolysaccharide (LPS)-induced B-cell proliferation, reduced B-cell migration towards the chemokines SDF-1α and CCL21 and downregulated IgM and IgG secretion. Mechanistically, these effects were mediated through a blockade of Kv1.3 and KCa3.1 potassium channels and resulted in an attenuated Ca(2+)-flux and activation of Erk1/2, Akt and NFATc1. Interestingly, NMDAR antagonist treatment increased the frequency of IL-10 producing B cells after BCR/CD40 stimulation.

Conclusions: Non-competitive NMDAR antagonists attenuate BCR and Toll-like receptor 4 (TLR4) B-cell signaling and effector function and can foster IL-10 production. Consequently, NMDAR antagonists may be useful to target B cells in autoimmune diseases or pathological systemic inflammation. The drugs' additional side effects on B cells should be considered in treatments of neuronal disorders with NMDAR antagonists.

Show MeSH
Related in: MedlinePlus