title: Targeting effector memory T cells with a selective peptide inhibitor of Kv1.3 channels for therapy of autoimmune diseases.
abstract: The voltage-gated Kv1.3 K(+) channel is a novel target for immunomodulation of autoreactive effector memory T (T(EM)) cells that play a major role in the pathogenesis of autoimmune diseases. We describe the characterization of the novel peptide ShK(L5) that contains l-phosphotyrosine linked via a nine-atom hydrophilic linker to the N terminus of the ShK peptide from the sea anemone Stichodactyla helianthus. ShK(L5) is a highly specific Kv1.3 blocker that exhibits 100-fold selectivity for Kv1.3 (K(d) = 69 pM) over Kv1.1 and greater than 250-fold selectivity over all other channels tested. ShK(L5) suppresses the proliferation of human and rat T(EM) cells and inhibits interleukin-2 production at picomolar concentrations. Naive and central memory human T cells are initially 60-fold less sensitive than T(EM) cells to ShK(L5) and then become resistant to the peptide during activation by up-regulating the calcium-activated K(Ca)3.1 channel. ShK(L5) does not exhibit in vitro cytotoxicity on mammalian cell lines and is negative in the Ames test. It is stable in plasma and when administered once daily by subcutaneous injection (10 mug/kg) attains "steady state" blood levels of approximately 300 pM. This regimen does not cause cardiac toxicity assessed by continuous EKG monitoring and does not alter clinical chemistry and hematological parameters after 2-week therapy. ShK(L5) prevents and treats experimental autoimmune encephalomyelitis and suppresses delayed type hypersensitivity in rats. ShK(L5) might prove useful for therapy of autoimmune disorders.
authors.affiliation: Department of Physiology and Biophysics, 291 Irvine Hall, Medical School, University of California-Irvine, Irvine, CA 92697-4561, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Beeton
authors.forename: Michael W
authors.initials: MW
authors.lastname: Pennington
authors.forename: Heike
authors.initials: H
authors.lastname: Wulff
authors.forename: Satendra
authors.initials: S
authors.lastname: Singh
authors.forename: Daniel
authors.initials: D
authors.lastname: Nugent
authors.forename: George
authors.initials: G
authors.lastname: Crossley
authors.forename: Ilya
authors.initials: I
authors.lastname: Khaytin
authors.forename: Peter A
authors.initials: PA
authors.lastname: Calabresi
authors.forename: Chao-Yin
authors.initials: CY
authors.lastname: Chen
authors.forename: George A
authors.initials: GA
authors.lastname: Gutman
authors.forename: K George
authors.initials: KG
authors.lastname: Chandy
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000188:drug therapy*; D002460:Cell Line; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000188:drug therapy; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000517:prevention & control; D017578:Immunoglobulin Class Switching / Q000187:drug effects; D007156:Immunologic Memory / Q000187:drug effects*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007376:Interleukin-2 / Q000096:biosynthesis; D051662:Kv1.1 Potassium Channel; D051664:Kv1.3 Potassium Channel; D008213:Lymphocyte Activation / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors*; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D007166:Immunosuppressive Agents; D007376:Interleukin-2; C496946:KCNA1 protein, human; C496973:KCNA3 protein, human; C496975:Kcna3 protein, rat; D051664:Kv1.3 Potassium Channel; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D051662:Kv1.1 Potassium Channel