Characterization of the Functional Properties of the Voltage-Gated Potassium Channel Kv1.3 in Human CD4+ T Lymphocytes

Abstract

Previous studies have shown that central memory T (TCM) cells predominantly use the calcium-dependent potassium channel KCa3.1 during acute activation, whereas effector memory T (TEM) cells use the voltage-gated potassium channel Kv1.3. Because Kv1.3-specific pharmacological blockade selectively inhibited anti-CD3-mediated proliferation, whereas naive T cells and TCM cells escaped inhibition due to up-regulation of KCa3.1, this difference indicated a potential for selective targeting of the TEM population. We examined the effects of pharmacological Kv1.3 blockers and a dominant-negative Kv1.x construct on T cell subsets to assess the specific effects of Kv1.3 blockade. Our studies indicated both TCM and TEM CD4+ T cells stimulated with anti-CD3 were inhibited by charybdotoxin, which can block both KCa3.1 and Kv1.3, whereas margatoxin and Stichodactyla helianthus toxin, which are more selective Kv1.3 inhibitors, inhibited proliferation and IFN-γ production only in the TEM subset. The addition of anti-CD28 enhanced proliferation of freshly isolated cells and rendered them refractory to S. helianthus, whereas chronically activated TEM cell lines appeared to be costimulation independent because Kv1.3 blockers effectively inhibited proliferation and IFN-γ regardless of second signal. Transduction of CD4+ T cells with dominant-negative Kv1.x led to a higher expression of CCR7+ TCM phenotype and a corresponding depletion of TEM. These data provide further support for Kv1.3 as a selective target of chronically activated TEM without compromising naive or TCM immune functions. Specific Kv1.3 blockers may be beneficial in autoimmune diseases such as multiple sclerosis in which TEM are found in the target organ.

Immunosuppression by N-Methyl-d-Aspartate Receptor Antagonists Is Mediated through Inhibition of Kv1.3 and KCa3.1 Channels in T Cells

“…As K Ca 3.1 is the functionally dominant K ϩ channel in naive and early memory T cells, and K v 1.3 is the dominant channel in effector memory T cells, NMDAR antagonists may target both populations (51). Similar to our results with ifenprodil, inhibition of T-cell function by K v 1.3 and K Ca 3.1 channel blockers could be rescued by CD28 costimulation (52,53), which supports our results that NMDAR antagonists act primarily via inhibition of these potassium channels. Furthermore, as T-regulatory (Treg) cells express similar numbers of K v 1.3 and K Ca 3.1 channels as naive T cells (54,55), NMDAR antagonists may also modulate Treg cell function.…”

Selective Inhibition of CCR7− Effector Memory T Cell Activation by a Novel Peptide Targeting Kv1.3 Channel in a Rat Experimental Autoimmune Encephalomyelitis Model

“…We also studied primary human T cells because they are physiologically similar to the human leukocyte microenvironment. The inhibitory effect of ADWX-1 on human T cells was similar to the reported effects of ShK on freshly isolated CD4 ϩ T cells, sorted T EM cells, or chronic T EM cells in humans (22).…”

Functional Blockade of the Voltage-gated Potassium Channel Kv1.3 Mediates Reversion of T Effector to Central Memory Lymphocytes through SMAD3/p21cip1 Signaling

“…Lentiviral Transduction of Activated CD4ϩ T Cells-Activated CD4ϩ T cells were transduced with the lentiviral vector particles as previously described (13). The DNKv1.x sequence codes for a Kv1.x molecule with a function-blocking mutation (GYG to AYA) in the pore-forming region.…”

“…While there are strong similarities between murine and human memory cells, the voltage-gated potassium channel, Kv1.3, has been reported to have unique functions in human lymphocytes that differ in murine systems due to compensatory activation of a chloride channel in mice in which Kv1.3 was knocked out (12). We and others have previously * This work was supported, in whole or in part, by National Institutes of Health demonstrated that T EM preferentially up-regulate expression of the outward rectifying Kv1.3 channel, and that pharmacological blockade of this channel inhibits a variety of effector functions of human T cells in vitro, and in vivo rat autoimmune models including delayed type hypersensitivity and relapsing EAE (13)(14)(15). We also previously reported that long-term functional blockade of Kv1.3 in human T cells using a dominant negative (Kv1.xDN) transduction strategy not only selectively inhibited T EM proliferation and cytokine production, but further caused inhibition of T CM differentiation into T EM (13,16).…”

“…We and others have previously * This work was supported, in whole or in part, by National Institutes of Health demonstrated that T EM preferentially up-regulate expression of the outward rectifying Kv1.3 channel, and that pharmacological blockade of this channel inhibits a variety of effector functions of human T cells in vitro, and in vivo rat autoimmune models including delayed type hypersensitivity and relapsing EAE (13)(14)(15). We also previously reported that long-term functional blockade of Kv1.3 in human T cells using a dominant negative (Kv1.xDN) transduction strategy not only selectively inhibited T EM proliferation and cytokine production, but further caused inhibition of T CM differentiation into T EM (13,16). In the present study, we sought to elucidate the mechanisms by which this channel regulates cell cycle and its role in T cell differentiation.…”