review article roles of lymphocyte kv1.3-channels in the...

Review ArticleRoles of Lymphocyte Kv13-Channels inthe Pathogenesis of Renal Diseases and Novel TherapeuticImplications of Targeting the Channels

Itsuro Kazama

Department of Physiology I Tohoku University Graduate School of Medicine Seiryo-cho Aoba-ku Sendai Miyagi 980-8575 Japan

Correspondence should be addressed to Itsuro Kazama kazaitsumedtohokuacjp

Received 17 December 2014 Accepted 25 February 2015

Academic Editor Augusto Vaglio

Copyright copy 2015 Itsuro KazamaThis is an open access article distributed under theCreativeCommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Delayed rectifier K+-channels (Kv13) are predominantly expressed in T lymphocytes Based on patch-clamp studies the channelsplay crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation Using selectivechannel inhibitors in experimental animal models in vivo studies then revealed the clinically relevant relationship between thechannel expression and the pathogenesis of autoimmune diseases In renal diseases in which ldquochronic inflammationrdquo or ldquotheoverstimulation of cellular immunityrdquo is responsible for the pathogenesis the overexpression of Kv13-channels in lymphocytespromotes their cellular proliferation and thus contributes to the progression of tubulointerstitial fibrosisWe recently demonstratedthat benidipine a potent dihydropyridine calcium channel blocker which also strongly and persistently inhibits the lymphocyteKv13-channel currents suppressed the proliferation of kidney lymphocytes and actually ameliorated the progression of renalfibrosis Based on the recent in vitro evidence that revealed the pharmacological properties of the channels the most recent studieshave revealed novel therapeutic implications of targeting the lymphocyte Kv13-channels for the treatment of renal diseases

1 Introduction

T lymphocytes predominantly express delayed rectifier K+-channels (Kv13) in their plasma membranes [1ndash3] Usingselective channel inhibitors patch-clamp studies revealedthat the channels generate the K+-diffusion potential acrossthe plasma membranes and play crucial roles in facilitatingcalcium influx necessary to trigger the lymphocyte activationand proliferation [3ndash6] Previous studies demonstrated theinvolvement of inflammatory leukocytes such as T lympho-cytes macrophages and mast cells in the pathogenesis ofrenal diseases such as glomerulonephritis chronic kidneydisease (CKD) or tubulointerstitial fibrosis [7ndash11] Sincelymphocytes are actually activated [12] and serum cytokinelevels are known to be elevated in patients with advanced-stage renal diseases [13 14] Kv13-channels expressed inlymphocytes would contribute to the progression of thediseases Regarding the molecular mechanisms by whichlymphocytes are activated the rise in the intracellular calciumconcentration stimulates the phosphatase calcineurin activ-ity which then dephosphorylates nuclear factor of activated

T cells (NFAT) enabling it to accumulate in the nucleus andbind to the promoter of the gene encoding interleukin 2 (IL-2)[6 15] (Figure 1)Therefore pharmacological targeting of cal-cineurin has been the main mechanism by which drugs suchas cyclosporine and tacrolimus exert their immunosuppres-sive effects [16] However recent studies have also revealedthat selective inhibition of lymphocyte Kv13-channels alsorepresses lymphocyte activity and thus suppresses cellularimmunity [17] Recent patch-clamp studies including ourshave shown that commonly used drugs such as calciumchannel blockers (CCBs) [18 19] macrolide antibioticsand HMG-CoA reductase inhibitors effectively suppress theKv13-channel currents in lymphocytes [20 21] Such studiessuggested the therapeutic efficacy of these drugs for thetreatment of renal diseases in which ldquochronic inflammationrdquoor ldquothe overstimulation of cellular immunityrdquo is responsiblefor the pathogenesis [22] By summarizing the previous andrecent findings obtained from studies in the relevant fieldsthis review provides an overview of the pathological rolesof lymphocyte Kv13-channels in renal diseases Based on

Hindawi Publishing CorporationMediators of InflammationVolume 2015 Article ID 436572 12 pageshttpdxdoiorg1011552015436572

2 Mediators of Inflammation

Calcineurin

Kv13 channel

NFAT

IL-2 promoter

K+

(i) T cell proliferation

Ca2+

Ca2+-

[Ca2+] uarr

(ii) IL-2 production

Figure 1 Kv13-channel-induced activation pathway of T lym-phocytes Kv13-channels expressed in T lymphocytes facilitate thecalcium influx necessary to trigger the lymphocyte activation andproliferation The rise in the intracellular calcium concentrationstimulates the phosphatase calcineurin activity which then dephos-phorylates nuclear factor of activated T cells (NFAT) enabling itto accumulate in the nucleus and bind to the promoter of the geneencoding interleukin 2 (IL-2)

the recent in vitro and in vivo evidence that revealed thepharmacological properties of the channels this review alsofocuses on the novel therapeutic implications of targeting thechannels for the treatment of renal diseases

2 Increased Numbers of Leukocytes in RatKidneys with Renal Diseases

Previous studies have described several laboratory modelsof renal diseases including ligation of the renal arterybranches or unilateral ureter [23 24] ablation of renal massby surgery [25 26] toxic nephritis [27 28] and immuno-logically induced nephritis [29 30] In the developmentof glomerulonephritis inflammatory leukocytes are initiallyrecruited from the bone marrow and infiltrate into therenal interstitium to produce proinflammatory cytokines[9] Therefore the kidneys from rat models with toxic orimmunologically induced nephritis were characterized by themassive infiltration of T-lymphocytes ormacrophages [9 27ndash30] On the other hand in rat models with 56 nephrectomy(subtotal nephrectomy) the injured kidneys were mainly

characterized by severe glomerulosclerosis which was pri-marily caused by the renal hemodynamic changes such asthe increased glomerular pressure and the protein overload[31 32] However with the increase in the serum creatininethe kidneys from these subtotally nephrectomized rats wereadditionally characterized by diffuse interstitial fibrosis withthe involvement of leukocyte infiltration [7 8 33] In ratswith subtotal nephrectomy followed by longer recoveryperiods serum creatinine and blood urea nitrogen levelswere markedly elevated indicating advanced chronic renalfailure (CRF) [11 34] In CRF rat kidneys with 8-weekrecovery period the cortical interstitium was expanded withfibroedema (Figure 2(a)(B) versus Figure 2(a)(A)) and therewas some infiltration of small round cells among spindle-shaped fibroblasts (Figure 2(a)(E) versus Figure 2(a)(D)) At14 weeks in addition to diffuse fibrosis in the corticaland medullary interstitium (Figure 2(a)(C)) the numbers ofsmall round cells were dramatically increased in the corticalinterstitium (Figure 2(a)(F)) Since the cortical expressionof CD3 and ED-1 surface markers for T lymphocytes andmacrophages was markedly elevated [11] they were regardedas inflammatory leukocytes such as T lymphocytes andmacrophages By immunohistochemistry the CD3- or ED-1-positive small round cells were actually costained withKi-67 a marker of cellular proliferation (Figures 2(b)(A)and 2(b)(B)) The findings indicated that T lymphocytesand macrophages were proliferating prominently within thecortical interstitium of advanced CRF rat kidneys [34]

Recently Liu et al demonstrated that CD4+ T-lympho-cytes especially Th2 cells contributed to the progression ofrenal fibrosis in a rat model of unilateral ureteral obstruction(UUO) [35] In the development of the tubulointerstitialfibrosis in CRF rat kidneys previous studies demonstratedthat the inflammatory leukocytes were initially recruitedfrom the bone marrow and infiltrated into the renal inter-stitium to trigger the proliferation of fibroblasts [36] In thiscontext using the rat model of advanced CRF the recentstudies further demonstrated that the infiltrated leukocytesproliferated in situ in the cortical interstitium and thusdramatically increased their numbers [11 34]

3 Physiological Roles of Kv13-ChannelsExpressed in T-Lymphocytes

A variety of ion channels that are expressed in T lymphocytesinclude voltage-dependent K+-channels (Kv) Ca2+-activatedK+-channels (KCa) Ca2+ release-activated Ca2+-channels(CRAC) Mg2+-inhibited Ca2+-permeable current (MIC)channels and swelling-activated Clminus channels (Clswell) [37]Among them human T lymphocytes predominantly expressKv13-channels in their plasma membranes [1 2] In patch-clamp studies using thymus-derived murine lymphocytes(thymocytes) stepwise changes in the membrane potentialevoked membrane currents characteristic to Kv-channels[18 20 21 38 39] Since margatoxin a selective inhibitorof Kv13-channels almost totally abolished the currents inlymphocytes (Figure 3(a)) [38] these membrane currentswere identified as Kv13-channel currents The physiological

Mediators of Inflammation 3

Sham

HampE

Massonrsquostrichrome

100120583m

CRF(8-week)

Advanced CRF(14-week)

20120583m

(A) (B) (C)

(D) (E) (F)

(a)

CD3Ki-67 ED-1Ki-67

20120583m

(A) (B)

(b)

Figure 2 Histological features of sham-operated (sham) CRF and advanced CRF rat kidneys (a) Hematoxylin and eosin (HampE) andMassonrsquos trichrome staining in sham-operated (sham) CRF (8 weeks after nephrectomy) and advanced CRF (14 weeks after nephrectomy)rat kidneys ((A) (B) and (C)) Low-power views of cortex Massonrsquos trichrome Magnification times20 ((D) (E) and (F)) High-power views ofcortical interstitium HampEMagnification times60 (b) Immunofluorescence staining using antibodies for CD3 ((A) green) and ED-1 ((B) green)costained with Ki-67 (red) in advanced CRF rat kidneys High-power views of the cortical interstitium Magnification times60 Modified from[34]

roles of Kv13-channels in lymphocytes have been identifiedby several in vitro studies Patch-clamp studies revealed thatthese channels generate the K+-diffusion potential across theplasma membranes and thus play a role in regulating theresting membrane potential and controlling the cell volume[40 41] The opening of Kv13-channels also brings about themembrane hyperpolarization and generates a driving forcefor the Ca2+ influx [4 5 37] Consequently it stimulates thefollowing Ca2+ signaling pathway necessary to trigger thelymphocyte activation and proliferation

4 Pathological Roles of LymphocyteKv13-Channels in Renal Diseases

Peripheral lymphocytes are activated and the serum cytokinelevels are known to be elevated in patients with end-stagerenal disease [12ndash14] Based on a previous patch-clamp study[42] the conductance of voltage-dependent K+-channels inlymphocytes was increased in such patients and the activityof the channels was strongly associated with the severityof renal dysfunction In experimental animal models of


Before

500pA

50ms

100nMmargatoxin

+80mV

minus80mV

(a)

0

400

300

200

Before Washout

100

10120583Mbenidipine

Peak

curr

ent d

ensit

y (p

Ap

F)

Washout Before

0

100

200

Before Washout10120583Mbenidipine

Pulse

-end

curr

ent d

ensit

y (p

Ap

F)

50ms200pA

benidipine

(A)

(B) (C)

10120583M

(b)

Figure 3 Effects of margatoxin and benidipine on Kv13 channel currents inmurine thymocytes Typical whole-cell current traces at differentvoltage steps recorded before and after the application of 100 nM margatoxin (a) or 10 120583M benidipine ((b)(A)) The currents were elicited byvoltage-steps from the holding potential of minus80mV to minus40 0 40 and 80mV as depicted in the voltage protocol Each pulse was appliedfor a 200-ms duration between 10-second intervals (b)(B) Peak current densities (peak currents normalized by the membrane capacitance)obtained from the records in (A) at the voltage-step of 80mV (b)(C) Pulse-end current densities (pulse-end currents normalized by themembrane capacitance) obtained from the records in (a) at the voltage-step of 80mV 119875 lt 005 versus before the drug application Valuesare means plusmn SEM (119899 = 5) Differences were analyzed by ANOVA followed by Dunnettrsquos or Studentrsquos 119905-test Modified from [18 38]

renal diseases such as renal allograft rejection [10] andglomerulonephritis [9] immunosuppression by the blockadeof lymphocyte Kv13-channels actually prevented or amelio-rated the progression of the diseases By using selective Kv13-channel inhibitors such as ShK and Psora-4 therapeutically[9 10] these studies demonstrated the contribution of thechannels to the pathogenesis of renal diseases

In previous studies the overexpression of Kv13-chann-nels was demonstrated in cells under various pathologicconditions such as cancer [43 44] ischemic heart disease[45] and autoimmune disorders [46 47] In autoimmunedisorders including multiple sclerosis rheumatoid arthritisand systemic lupus erythematosus the inhibition of theKv13-channel modulated the calcium influx patterns in T


lymphocytes and thus exerted immunosuppressive effects[48ndash50] Recently using a rat model with advanced CRFwe demonstrated for the first time that Kv13-channelswere overexpressed in proliferating leukocytes within fibrotickidneys [11] In our study margatoxin one of the mostpotent inhibitors of Kv13-channels which almost totallyinhibits the channel currents in lymphocytes (Figure 3(a))[38] decreased the number of proliferating lymphocytesand ameliorated the progression of renal fibrosis Thesefindings indicated that the overexpression of Kv13-channelsin kidney lymphocytes promoted their cellular proliferationin advanced CKD As previously demonstrated in cancercells [51] the membrane hyperpolarization induced by theoverexpression of the channels is thought to trigger the cellcycle progression in lymphocytes [52 53] Since the cytokinesproduced by lymphocytes stimulate the activity of fibroblaststo produce collagen [36] the proliferating lymphocytes in theinterstitium would promote the progression of renal fibrosisin advanced CRF contributing to the rapid deterioration ofrenal function [11]

5 Suppressive Effects of Benidipine onLymphocyte Kv13-Channels

In addition to their cardiovascular effects on hypertensionand ischemic heart disease [54] CCBs are also known to exertimmunosuppressive properties in humans [55 56] Accord-ing to several in vitro studies CCBs including nifedipineverapamil and diltiazem repress the migration of leukocytesand inhibit their proliferation [57 58] Recently using humanperipheral leukocytes Matsumori et al demonstrated thatCCBs also suppress the production of proinflammatorycytokines such as IL-1120573 tumor necrosis factor 120572 (TNF-120572) and interferon 120574 (IFN-120574) [59 60] According to theirstudies 14-dihydropyridine (DHP) CCBs including nifedip-ine amlodipine and benidipine which are highly lipophiliccompared to the other types of CCBs [61 62] exert rel-atively stronger immunomodulatory effects Among thembenidipine is one of the most lipophilic and longest actingDHP CCBs [63 64] In our patch-clamp study using murinethymocytes [18] benidipine almost totally and irreversiblyinhibited the Kv13-channel currents (Figure 3(b)) indicatingits usefulness as a potent Kv13-channel inhibitor Althoughthe effects of benidipine on cytokine production have notyet been directly examined [59 60] the marked inhibitionof the channel currents by this drug strongly suggested itshigher immunosuppressive potency than the other CCBsMoreover the persistent effect of benidipine in decreasing thechannel currents may suggest its longer duration of action inthymocytes as previously demonstrated in cardiomyocytes[64] and isolated coronary arteries [65]

6 Therapeutic Efficacy of Benidipineagainst the Progression of TubulointerstitialFibrosis in Advanced CRF

In our recent study the overexpression of Kv13-channelsin kidney lymphocytes was strongly associated with their

in situ proliferation in advanced CRF rat kidneys [11] andthe channel inhibition by margatoxin actually decreased thenumber of infiltrating leukocytes and slowed the progressionof renal fibrosis Based on one of our patch-clamp studies [18]since benidipine was also highly potent as a Kv13-channelinhibitor the therapeutic effects of this drug on CKD wereexamined in ourmost recent study [34] Previous studies haveshown the therapeutic efficacy of antihypertensive drugssuch as CCBs [66] and angiotensin converting enzymeinhibitors (ACEIs) [67] for the prevention of glomeru-losclerosis since these drugs hemodynamically ameliorateglomerular hypertension However it is not well known howthese pharmacological approaches slow the progression oftubulointerstitial fibrosis independently of their effects onglomerulosclerosis

In advanced CRF rat kidneys with benidipine treatmentthe size of the cortical interstitium which included the areasof fibrosis edema and the inflammatory leukocyte infiltra-tion was smaller (Figure 4(a)(B) versus Figure 4(a)(A)) andthe number of proliferating leukocytes was much reduced(Figure 4(b)(B) versus Figure 4(b)(A)) together with a signif-icant decrease in the proinflammatory cytokine expression(Figure 4(c)) In these kidneys Massonrsquos trichrome stainingand the immunohistochemistry for fibrosis markers such ascollagen III demonstrated less staining in the cortical inter-stitium (Figures 5(a)(B) and 5(a)(D) versus Figures 5(a)(A)and 5(a)(C)) However in the glomeruli the amount ofperiodic acid Schiff positive material was a comparable withthat in vehicle-treated CRF rat kidneys (Figure 5(b)(B) versusFigure 5(b)(A))These results indicated that benidipine ame-liorated the progression of renal fibrosis without affecting thedeterioration of glomerulosclerosis Benidipinewhich blocksL- and T-types of calcium channels in the renal vasculatureis known to dilate both afferent and efferent arterioles of theglomeruli and to reduce glomerular hypertension [68] In ourrecent study however benidipine did not decrease the severeproteinuria nor did it improve the systemic hypertensionin advanced CRF rats [34] Therefore factors other thanreducing the glomerular capillary pressure may also beinvolved in its pharmacological effects of ameliorating therenal injury [66] Recently benidipine was shown to reducethe circulating levels of inflammatory cytokines or proteinssuch as IL-6 and high mobility group box-1 (HMGB-1) inpatients with chronic kidney disease [69] Since IL-6 andHMGB-1 accelerate the inflammation of systemic organs bypromoting lymphocyte activation and proliferation [14 70]such effects of benidipine may have therapeutic potential forslowing the progression of renal fibrosis in advanced CRF

7 Novel Therapeutic Implications ofTargeting Lymphocyte Kv13-Channels byCommonly Used Drugs

Grgic et al demonstrated the therapeutic efficacy of blockingthe intermediate-conductance Ca2+-activated K+-channels(KCa31) for renal fibrosis since fibroblasts overexpressedthe channels under a pathologic condition [24] In a sepa-rate animal study they also demonstrated the prophylactic


HampE

Vehicle-treated Benidipine-treated

100120583m

(A) (B)

(a)


Ki-67

20120583m

(A) (B)

(b)

12

0

40

80

10

0

50

IL-2

mRN

AG

APD

H m

RNA

ratio

IFN

-120574m

RNA

GA

PDH

mRN

A ra

tio

lowastlowast

Vehicle-treated Benidipine-treated Vehicle-treated Benidipine-treated

(c)

Figure 4 Histological features of vehicle- and benidipine-treated CRF rat kidneys and the expression of proinflammatory cytokines(a) Hematoxylin and eosin staining (HampE) in vehicle-treated and benidipine-treated CRF rat kidneys Low-power views of the cortexMagnification times20 (b) Immunohistochemistry using antibody for Ki-67 (brown) in vehicle- and benidipine-treated CRF rat kidneys High-power views of the cortical interstitium Magnification times60 (c) The abundance of IL-2 mRNA (left) and interferon-120574 (IFN-120574) (right) in therenal cortex of vehicle-treated and benidipine-treated CRF rat kidneys lowast119875 lt 005 versus vehicle-treated CRF rats Values are means plusmn SEM(119899 = 5) Differences were analyzed by ANOVA followed by Dunnettrsquos or Studentrsquos 119905-test Modified from [34]




100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)

Figure 5 Fibrotic marker expression and histological features of glomeruli in vehicle- and benidipine-treated CRF rat kidneys (a) Massonrsquostrichrome staining ((A) and (B)) and immunohistochemistry using antibody for collagen III ((C) and (D) brown) in vehicle-treated andbenidipine-treated CRF rat kidneys Low-power views of the cortex Magnification times20 (b) Periodic acid Schiff (PAS) staining in vehicle-treated and benidipine-treated CRF rat kidneys Low-power views of the cortex Magnification times20 Modified from [34]

efficacy of blocking lymphocyte Kv13-channels to preventrenal allograft rejection [10] As an extension of these stud-ies our studies further suggested that targeting the Kv13-channels overexpressed in leukocytes would also be usefulfor the treatment of renal fibrosis in advanced CRF [1134] In our series of patch-clamp studies in addition toCCBs such as benidipine and nifedipine [18] macrolideantibiotics and HMG-CoA reductase inhibitors (statins) alsoeffectively suppressed lymphocyte Kv13-channel currents

[20 21] (Table 1) According to separate in vitro studies thesedrugs exerted immunomodulatory properties besides theiranti-inflammatory antimicrobial and anticholesterol effects[56 71ndash75] Since lymphocyte Kv13-channels trigger calciuminflux which is necessary for IL-2 synthesis [15] and sincechannel blockade by highly selective inhibitors includingmargatoxin ShK-Dap22 and PAP-1 actually repressed theimmune response in lymphocytes [38 76ndash78] (Table 2) thesuppressive effects of NSAIDs macrolide antibiotics and


Table 1 Summary of changes in peak and pulse-end currents after application of CCBs macrolide and HMG-CoA reductase inhibitors(statins)

Drugs 119873

Peak current density (pApF) Pulse-end currentpeak current (119868119868peak) ()Before After Before After

Nifedipine (100120583M) 5 297 plusmn 33 196 plusmn 26 613 plusmn 18 262 plusmn 54

Benidipine (10 120583M) 5 384 plusmn 47 120 plusmn 15 534 plusmn 46 114 plusmn 021

Clarithromycin (100120583M) 5 277 plusmn 44 896 plusmn 10 485 plusmn 14 158 plusmn 10

Pravastatin (1mM) 5 309 plusmn 16 278 plusmn 17 521 plusmn 24 334 plusmn 42

Lovastatin (10 120583M) 5 301 plusmn 12 237 plusmn 50 551 plusmn 04 268 plusmn 07

Simvastatin (10 120583M) 5 307 plusmn 37 225 plusmn 28 473 plusmn 39 121 plusmn 22

Data modified from [18 20 21]Values are means plusmn SEMCCBs calcium channel blockers119875 lt 005 versus before drug application

Table 2 Summary of Kv13-channel inhibition and its functional outcomes

Authors Cells Kv13-channel inhibitors used Functional outcomes ofKv13-channel inhibition

Villalonga et al [76] Raw 2647 macrophagesJurkit T-lymphocytes

MargatoxinCharybdotoxin Immunomodulatory effect

Kalman et al [77] L929 cell line stablyexpressing Kv13 ShK-Dap22 Immunomodulatory effect

Schmitz et al [78] L929 cell line stablyexpressing Kv13 PAP-1 Immunomodulatory effect

Kazama et al [38] Murine thymocytes Margatoxin Membrane stabilizationImmunomodulatory effect

Leanza et al [80] Cancer cell lines(MCF-7 DLD-1 etc)

PAP-1Psora-4

Cellular proliferationApoptosis regulation

Hamilton et al [79] Skeletal muscle celllines (C2C12 L6)

MargatoxinPAP-1Psora-4

Increased glucose uptakeIncreased AMPK activity

ShK Stichodactyla helianthus toxin PAP-1 5-(4-phenylbutoxy) psoralenAMPK 51015840 adenosine monophosphate-activated protein kinase

statins on the channel currents were considered to contributeto their immunomodulatory properties Additionally as pre-viously detected by the whole-cell patch-clamp technique[38] the amplitude of the peak channel currents was deeplyassociated with the ldquoactivationrdquo of the channel currents [21]Therefore the stronger suppression of the peak currents bymacrolide antibiotics or statins may indicate their higherimmunosuppressive potency In this regard besides the use ofthe previously developed selective blockers for the channels[78ndash80] the use of CCBs macrolide antibiotics or statinscould also potentially be useful as antifibrotic agents inpatients with advanced CKD (Figure 6) The most likelyside effects of the Kv13-channel inhibition include epilepticseizures or enteric twitches since the channels are alsoexpressed in the synapses of both central and enteric nervoussystems [81 82] In normal rat kidneys Kv13-channels areexpressed in some proximal tubules [9] and predominantly inthe basolateral membranes of the inner medullary collectingduct cells [83] In these cells the channels regulated thecellular or total body fluid volume bymaintaining the drivingforce for Na+ reabsorptionTherefore the channel inhibitionmay also affect such tubular functions and the urinary K+

secretion which was actually demonstrated in previous stud-ies using isolated collecting ducts [84] However compared tothe highly selective inhibitors which were originally derivedfrom venom scorpion or sea anemone peptide toxins [4979 85 86] the drugs such as CCBs macrolide antibioticsor statins could be used more safely since they have beenemployed in a common clinical practice for a longer periodof time

8 Conclusions and Perspectives

In a physiological condition Kv13-channels expressed in Tlymphocytes play crucial roles in the initiation of the immuneresponse In renal diseases such as CKD acute glomeru-lonephritis and renal allograft rejection the channels con-tribute to the pathogenesis of the diseases In rat kidneyswith advanced CRF the overexpression of the channels inlymphocytes facilitated the progression of tubulointerstitialfibrosis by promoting lymphocyte proliferation suggestingthat the channel could be a potent therapeutic target foradvanced-stage CKD Benidipine one of themost commonlyused CCBs which also strongly and persistently inhibits


IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr

T cell proliferation darr

Progression of CKD darr

Ca2+-

[Ca2+] darr

Figure 6 Therapeutic implications of targeting lymphocyte Kv13-channels in the treatment of CKD In addition to benidipine oneof the calcium channel blockers (CCBs) macrolide antibiotics andstatins which effectively inhibit lymphocyte Kv13-channels couldalso potentially be useful in the treatment or the prevention ofchronic kidney disease (CKD)

the lymphocyte Kv13-channel currents suppressed the pro-liferation of kidney lymphocytes and actually amelioratedthe progression of renal fibrosis Since other drugs such asNSAIDs macrolide antibiotics and statins also effectivelysuppress the channel currents in lymphocytes they may beuseful for treating or preventing renal diseases

ldquoChronic inflammatory diseasesrdquo are a category of dis-eases in which ldquochronic inflammationrdquo or ldquothe overstimula-tion of cellular immunityrdquo is responsible for the pathogenesis[22] Besides infectious diseases and autoimmune disordersa number of diseases such as cancer neuroinflammatorydiseases and metabolic disorders nowadays fall into thiscategory [87] Recently in addition to renal diseases theinvolvement of lymphocyte Kv13-channels has also beendemonstrated in the development of these ldquochronic inflam-matory diseasesrdquo [43ndash45 48ndash50 52 88ndash91] Therefore ourfuture tasks would include revealing the as yet unknownsignificance of the channels in the pathogenesis of thesediseases and revealing novel therapeutic applications basedon targeting these channels

Conflict of InterestsThe author declares that he has no conflict of interests

AcknowledgmentsThis work was supported by MEXT KAKENHI Grant no25860155 and Miyagi Kidney Foundation grant

References

[1] M D Cahalan K G Chandy T E DeCoursey and S GuptaldquoA voltage-gated potassium channel in human T lymphocytesrdquoJournal of Physiology vol 358 pp 197ndash237 1985

[2] T E DeCoursey K G Chandy S Gupta and M D CahalanldquoVoltage-gated K+ channels in human T lymphocytes a role inmitogenesisrdquo Nature vol 307 no 5950 pp 465ndash468 1984

[3] R S Lewis and M D Cahalan ldquoPotassium and calciumchannels in lymphocytesrdquo Annual Review of Immunology vol13 pp 623ndash653 1995

[4] M D Cahalan H Wulff and K G Chandy ldquoMolecular prop-erties and physiological roles of ion channels in the immunesystemrdquo Journal of Clinical Immunology vol 21 no 4 pp 235ndash252 2001

[5] L Hu M Pennington Q Jiang K A Whartenby and PA Calabresi ldquoCharacterization of the functional properties ofthe voltage-gated potassium channel Kv13 in human CD4+ Tlymphocytesrdquo Journal of Immunology vol 179 no 7 pp 4563ndash4570 2007

[6] I Kazama ldquoPhysiological significance of delayed rectifier K+channels (Kv13) expressed in T lymphocytes and their patho-logical significance in chronic kidney diseaserdquo The Journal ofPhysiological Sciences vol 65 no 1 pp 25ndash35 2015

[7] K Kumano K Kogure T Tanaka and T Sakai ldquoA newmethodof inducing experimental chronic renal failure by cryosurgeryrdquoKidney International vol 30 no 3 pp 433ndash436 1986

[8] S E Jones D J Kelly A J Cox Y Zhang R M Gow and RE Gilbert ldquoMast cell infiltration and chemokine expression inprogressive renal diseaserdquo Kidney International vol 64 no 3pp 906ndash913 2003

[9] T Hyodo T Oda Y Kikuchi et al ldquoVoltage-gated potas-sium channel Kv13 blocker as a potential treatment for ratanti-glomerular basement membrane glomerulonephritisrdquoTheAmerican Journal of PhysiologymdashRenal Physiology vol 299 no6 pp F1258ndashF1269 2010

[10] I Grgic H Wulff I Eichler C Flothmann R Kohler and JHoyer ldquoBlockade of T-lymphocyteKCa31 andKv13 channels asnovel immunosuppression strategy to prevent kidney allograftrejectionrdquo Transplantation Proceedings vol 41 no 6 pp 2601ndash2606 2009

[11] I Kazama Y Maruyama Y Endo et al ldquoOverexpression ofdelayed rectifier K+ channels promotes in situ proliferation ofleukocytes in rat kidneys with advanced chronic renal failurerdquoInternational Journal of Nephrology vol 2012 Article ID 5815818 pages 2012

[12] L Chatenoud B Dugas G Beaurain et al ldquoPresence ofpreactivated T cells in hemodialyzed patients their possible rolein altered immunityrdquo Proceedings of the National Academy ofSciences of the United States of America vol 83 no 19 pp 7457ndash7461 1986

[13] G A Kaysen andV Kumar ldquoInflammation in ESRD causes andpotential consequencesrdquo Journal of Renal Nutrition vol 13 no2 pp 158ndash160 2003

[14] DV Barreto F C Barreto S Liabeuf et al ldquoPlasma interleukin-6 is independently associated with mortality in both hemodial-ysis and pre-dialysis patients with chronic kidney diseaserdquoKidney International vol 77 no 6 pp 550ndash556 2010

[15] K G Chandy H Wulff C Beeton M Pennington G AGutman andMD Cahalan ldquoK+ channels as targets for specificimmunomodulationrdquo Trends in Pharmacological Sciences vol25 no 5 pp 280ndash289 2004


[16] K Sugiyama K Isogai A Toyama et al ldquoCorrelation betweenthe pharmacological efficacy of cyclosporine and tacrolimusas evaluated by the lymphocyte immunosuppressant sensitivitytest (LIST) and the MTT assay procedure in patients beforeand after renal transplantationrdquo International Journal of ClinicalPharmacology andTherapeutics vol 49 no 2 pp 145ndash152 2011

[17] S Rangaraju V Chi M W Pennington and K G ChandyldquoKv13 potassium channels as a therapeutic target in multiplesclerosisrdquo Expert Opinion on Therapeutic Targets vol 13 no 8pp 909ndash924 2009

[18] I Kazama Y Maruyama and M Matsubara ldquoBenidipinepersistently inhibits delayed rectifier K+-channel currents inmurine thymocytesrdquo Immunopharmacology and Immunotoxi-cology vol 35 no 1 pp 28ndash33 2013

[19] A Baba M Tachi Y Maruyama and I Kazama ldquoSuppres-sive effects of diltiazem and verapamil on delayed rectifierK+-channel currents in murine thymocytesrdquo PharmacologicalReports 2015

[20] I Kazama and Y Maruyama ldquoDifferential effects of clar-ithromycin and azithromycin on delayed rectifier K+-channelcurrents inmurine thymocytesrdquoPharmaceutical Biology vol 51no 6 pp 760ndash765 2013

[21] I Kazama A Baba and Y Maruyama ldquoHMG-CoA reduc-tase inhibitors pravastatin lovastatin and simvastatin suppressdelayed rectifier K(+)-channel currents in murine thymocytesrdquoPharmacological Reports vol 66 no 4 pp 712ndash717 2014

[22] G A Heap and D A van Heel ldquoThe genetics of chronicinflammatory diseasesrdquo Human Molecular Genetics vol 18 no1 pp R101ndashR106 2009

[23] L V Avioli S Scott S W Lee and H F de Luca ldquoIntestinalcalcium absorption Nature of defect in chronic renal diseaserdquoScience vol 166 no 3909 pp 1154ndash1156 1969

[24] I Grgic E Kiss B P Kaistha et al ldquoRenal fibrosis is attenuatedby targeted disruption of KCa31 potassium channelsrdquo Proceed-ings of the National Academy of Sciences of the United States ofAmerica vol 106 no 34 pp 14518ndash14523 2009

[25] R Platt M H Roscoe and F W Smith ldquoExperimental renalfailurerdquo Clinical Science vol 11 no 3 pp 217ndash231 1952

[26] A B Morrison ldquoExperimentally induced chronic renal insuffi-ciency in the ratrdquo Laboratory Investigation vol 11 pp 321ndash3321962

[27] S A Bencosme R S Stone H Latta and S C Madden ldquoAcutetubular and glomerular lesions in rat kidneys after uraniumrdquoArchives of Pathology vol 69 pp 470ndash476 1960

[28] S Fukuda and J D Kopple ldquoChronic uremia syndrome in dogsinducedwith uranyl nitraterdquoNephron vol 25 no 3 pp 139ndash1431980

[29] M E M Allison C B Wilson and C W Gottschalk ldquoPatho-physiology of experimental glomerulonephritis in ratsrdquo TheJournal of Clinical Investigation vol 53 no 5 pp 1402ndash14231974

[30] Y Kondo H Shigematsu and Y Kobayashi ldquoCellular aspects ofrabbitMasugi nephritis II Progressive glomerular injuries withcrescent formationrdquo Laboratory Investigation vol 27 no 6 pp620ndash631 1972

[31] MMichimata I Kazama KMizukami et al ldquoUrinary concen-tration defect and limited expression of sodium cotransporterrBSC1 in a rat model of chronic renal failurerdquo Nephron vol 93no 2 pp p34ndashp41 2003

[32] K Suzuki R Hatano M Michimata et al ldquoResidual urinaryconcentrating ability and AQP2 expression in a rat model for

chronic renal failurerdquoNephron Physiology vol 99 no 1 pp p16ndashp22 2005

[33] S Sanada H Toyama Y Ejima and M Matsubara ldquoPotentialfor erythropoietin synthesis in kidney of uraemic rat altersdepending on severity of renal failurerdquo Nephrology vol 14 no8 pp 735ndash742 2009

[34] I Kazama A Baba M Matsubara Y Endo H Toyama and YEjima ldquoBenidipine suppresses in situ proliferation of leukocytesand slows the progression of renal fibrosis in rat kidneyswith advanced chronic renal failurerdquo Nephron ExperimentalNephrology vol 128 no 1-2 pp 67ndash79 2014

[35] L Liu P Kou Q Zeng et al ldquoCD4+ T lymphocytes especiallyTh2 cells contribute to the progress of renal fibrosisrdquo TheAmerican Journal of Nephrology vol 36 no 4 pp 386ndash3962012

[36] A M El Nahas S Anderson and K P G Harris EdsMechanisms and Management of Progressive Renal FailureOxford University Press London UK 2000

[37] M D Cahalan and K G Chandy ldquoThe functional network ofion channels in T lymphocytesrdquo Immunological Reviews vol231 no 1 pp 59ndash87 2009

[38] I Kazama Y Maruyama Y Murata and M Sano ldquoVoltage-dependent biphasic effects of chloroquine on delayed rectifierK+-channel currents in murine thymocytesrdquo Journal of Physio-logical Sciences vol 62 no 3 pp 267ndash274 2012

[39] I Kazama Y Maruyama and Y Murata ldquoSuppressive effectsof nonsteroidal anti-inflammatory drugs diclofenac sodiumsalicylate and indomethacin on delayed rectifier K+-channelcurrents in murine thymocytesrdquo Immunopharmacology andImmunotoxicology vol 34 no 5 pp 874ndash878 2012

[40] Y Ishida and TM Chused ldquoLack of voltage sensitive potassiumchannels and generation of membrane potential by sodiumpotassium ATPase in murine T lymphocytesrdquo Journal ofImmunology vol 151 no 2 pp 610ndash620 1993

[41] CDeutsch and LQ Chen ldquoHeterologous expression of specificK+ channels in T lymphocytes functional consequences forvolume regulationrdquo Proceedings of the National Academy ofSciences of the United States of America vol 90 no 21 pp10036ndash10040 1993

[42] A Teisseyre S C Zmonarski M Klinger J W Mozrzymasand SMiekisz ldquoPatch-clamp study onT-lymphocyte potassiumconductance in patients with chronic renal failurerdquo Nephronvol 72 no 4 pp 587ndash594 1996

[43] M Abdul and N Hoosein ldquoExpression and activity of potas-sium ion channels in human prostate cancerrdquo Cancer Lettersvol 186 no 1 pp 99ndash105 2002

[44] S H Jang K S Kang P D Ryu and S Y Lee ldquoKv13 voltage-gated K+channel subunit as a potential diagnostic marker andtherapeutic target for breast cancerrdquo BMB Reports vol 42 no8 pp 535ndash539 2009

[45] S Huang C-T Zhang J-R Tang L Cai Z Zhang and M-G Zhou ldquoUpregulated voltage-gated potassium channel Kv13on CD4+CD28null T lymphocytes from patients with acutecoronary syndromerdquo Journal of Geriatric Cardiology vol 7 no1 pp 40ndash46 2010

[46] G Toldi A Bajnok D Dobi et al ldquoThe effects of Kv13and IKCa1 potassium channel inhibition on calcium influxof human peripheral T lymphocytes in rheumatoid arthritisrdquoImmunobiology vol 218 no 3 pp 311ndash316 2013

[47] H Rus C A Pardo L Hu et al ldquoThe voltage-gated potassiumchannel Kv13 is highly expressed on inflammatory infiltrates in


multiple sclerosis brainrdquo Proceedings of the National Academyof Sciences of the United States of America vol 102 no 31 pp11094ndash11099 2005

[48] C Orban E Biro E Grozdics A Bajnok and G ToldildquoModulation of T lymphocyte calcium influx patterns via theinhibition of Kv13 and IKCa1 potassium channels in autoim-mune disordersrdquo Frontiers in Immunology vol 4 article 2342013

[49] S Han H Yi S J Yin et al ldquoStructural basis of a potent peptideinhibitor designed for Kv13 channel a therapeutic target ofautoimmune diseaserdquo The Journal of Biological Chemistry vol283 no 27 pp 19058ndash19065 2008

[50] C Beeton H Wulff J Barbaria et al ldquoSelective blockade ofT lymphocyte K+ channels ameliorates experimental autoim-mune encephalomyelitis a model for multiple sclerosisrdquo Pro-ceedings of the National Academy of Sciences of the United Statesof America vol 98 no 24 pp 13942ndash13947 2001

[51] W FWonderlin and J S Strobl ldquoPotassium channels prolifera-tion and G1 progressionrdquo Journal of Membrane Biology vol 154no 2 pp 91ndash107 1996

[52] S H Jang S Y Choi P D Ryu and S Y Lee ldquoAnti-proliferativeeffect of Kv13 blockers in A549 human lung adenocarcinoma invitro and in vivordquo European Journal of Pharmacology vol 651no 1ndash3 pp 26ndash32 2011

[53] HOuadid-Ahidouch andAAhidouch ldquoK+ channel expressionin human breast cancer cells Involvement in cell cycle regula-tion and carcinogenesisrdquo Journal of Membrane Biology vol 221no 1 pp 1ndash6 2008

[54] E Braunwald ldquoMechanism of action of calcium-channel-blocking agentsrdquoTheNew England Journal of Medicine vol 307no 26 pp 1618ndash1627 1982

[55] I Palamaras and K Kyriakos ldquoCalcium antagonists in derma-tology a review of the evidence and research-based studiesrdquoDermatology Online Journal vol 11 no 2 2005

[56] M Horvath Z Mezey A Josfay I Nanay M Varsanyi and SGero ldquoThe effect of some drugs on in vitro cellular immunereactions andon circulating immune complexes in patientswithmyocardial infarctionrdquo Journal of Investigational Allergologyand Clinical Immunology vol 1 pp 404ndash410 1991

[57] D L Birx M Berger and T A Fleischer ldquoThe interference ofT cell activation by calcium channel blocking agentsrdquo Journal ofImmunology vol 133 no 6 pp 2904ndash2909 1984

[58] K B Bacon J Westwick and R D R Camp ldquoPotent andspecific inhibition of IL-8- IL-1 alpha- and IL-1 beta-induced invitro human lymphocyte migration by calcium channel antag-onistsrdquo Biochemical and Biophysical Research Communicationsvol 165 no 1 pp 349ndash354 1989

[59] A Matsumori R Nishio and Y Nose ldquoCalcium channel block-ers differentially modulate cytokine production by peripheralblood mononuclear cellsrdquo Circulation Journal vol 74 no 3 pp567ndash571 2010

[60] W Liu and A Matsumori ldquoCalcium channel blockers andmodulation of innate immunityrdquo Current Opinion in InfectiousDiseases vol 24 no 3 pp 254ndash258 2011

[61] T Furukawa T Yamakawa T Midera T Sagawa Y Moriand T Nukada ldquoSelectivities of dihydropyridine derivativesin blocking Ca2+ channel subtypes expressed in 119883119890119899119900119901119906119904119900119900119888119910119905119890119904rdquoJournal of Pharmacology and Experimental Therapeutics vol291 no 2 pp 464ndash473 1999

[62] L G Herbette D W Chester and D G Rhodes ldquoStructuralanalysis of drug molecules in biological membranesrdquo Biophysi-cal Journal vol 49 no 1 pp 91ndash94 1986

[63] M Kitakaze K Node T Minamino H Asanuma T Kuzuyaand M Hori ldquoA Ca channel blocker benidipine increasescoronary blood flow and attenuates the severity of myocardialischemia via NO-dependent mechanisms in dogsrdquo Journal ofthe American College of Cardiology vol 33 no 1 pp 242ndash2491999

[64] M Yamamoto Y Gotoh Y Imaizumi and M WatanabeldquoMechanisms of long-lasting effects of benidipine onCa currentin guinea-pig ventricular cellsrdquo British Journal of Pharmacologyvol 100 no 4 pp 669ndash676 1990

[65] A Karasawa and K Kubo ldquoCalcium antagonistic effects andthe in vitro duration of actions of KW-3049 a new 14-dihydropyridine derivative in isolated canine coronary arter-iesrdquo Japanese Journal of Pharmacology vol 47 no 1 pp 35ndash441988

[66] K Hayashi K Homma S Wakino et al ldquoT-type Ca channelblockade as a determinant of kidney protectionrdquo Keio Journalof Medicine vol 59 no 3 pp 84ndash95 2010

[67] G Remuzzi ldquoRandomised placebo-controlled trial of effect oframipril on decline in glomerular filtration rate and risk ofterminal renal failure in proteinuric non-diabetic nephropathyThe GISEN Group (Gruppo Italiano di Studi Epidemiologici inNefrologia)rdquoThe Lancet vol 349 no 9069 pp 1857ndash1863 1996

[68] K Hayashi S Wakino K Homma N Sugano and T SarutaldquoPathophysiological significance of T-type Ca2+ channels Roleof T-type Ca2+ channels in renal microcirculationrdquo Journal ofPharmacological Sciences vol 99 no 3 pp 221ndash227 2005

[69] T Nakamura E Sato N Fujiwara et al ldquoComparative effectsof benidipine and amlodipine on proteinuria urinary 8-OHdGurinary L-FABP and inflammatory and atherosclerosis markersin early-stage chronic kidney diseaserdquoThe American Journal ofthe Medical Sciences vol 339 no 2 pp 157ndash163 2010

[70] U Andersson H Wang K Palmblad et al ldquoHigh mobilitygroup 1 protein (HMG-1) stimulates proinflammatory cytokinesynthesis in human monocytesrdquo The Journal of ExperimentalMedicine vol 192 no 4 pp 565ndash570 2000

[71] K Sugiyama R Shirai H Mukae et al ldquoDiffering effects ofclarithromycin and azithromycin on cytokine production bymurine dendritic cellsrdquo Clinical and Experimental Immunologyvol 147 no 3 pp 540ndash546 2007

[72] K Morikawa J Zhang M Nonaka and S Morikawa ldquoModu-latory effect of macrolide antibiotics on the Th1- and Th2-typecytokine productionrdquo International Journal of AntimicrobialAgents vol 19 no 1 pp 53ndash59 2002

[73] A A Khan T R Slifer F G Araujo and J S Remington ldquoEffectof clarithromycin and azithromycin on production of cytokinesby human monocytesrdquo International Journal of AntimicrobialAgents vol 11 no 2 pp 121ndash132 1999

[74] H Bessler H Salman M Bergman R Straussberg and MDjaldetti ldquoIn vitro effect of statins on cytokine productionandmitogen response of human peripheral bloodmononuclearcellsrdquo Clinical Immunology vol 117 no 1 pp 73ndash77 2005

[75] R S Rosenson C C Tangney and L C Casey ldquoInhibitionof proinflammatory cytokine production by pravastatinrdquo TheLancet vol 353 no 9157 pp 983ndash984 1999

[76] N Villalonga M David J Bielanska et al ldquoImmunomodula-tory effects of diclofenac in leukocytes through the targetingof Kv13 voltage-dependent potassium channelsrdquo BiochemicalPharmacology vol 80 no 6 pp 858ndash866 2010


[77] K Kalman M W Pennington M D Lanigan et al ldquoShk-Dap22 a potent Kv13-specific immunosuppressive polypep-tiderdquo The Journal of Biological Chemistry vol 273 no 49 pp32697ndash32707 1998

[78] A Schmitz A Sankaranarayanan P Azam et al ldquoDesignof PAP-1 a selective small molecule Kv13 blocker for thesuppression of effectormemory t cells in autoimmune diseasesrdquoMolecular Pharmacology vol 68 no 5 pp 1254ndash1270 2005

[79] D L Hamilton C Beall S Jeromson C Chevtzoff D JCuthbertson and M L J Ashford ldquoKv13 inhibitors havedifferential effects on glucose uptake and AMPK activity inskeletalmuscle cell lines andmouse ex vivo skeletalmusclerdquoTheJournal of Physiological Sciences vol 64 no 1 pp 13ndash20 2014

[80] L Leanza P OrsquoReilly A Doyle et al ldquoCorrelation betweenpotassium channel expression and sensitivity to drug-inducedcell death in tumor cell linesrdquo Current Pharmaceutical Designvol 20 no 2 pp 189ndash200 2014

[81] R J Lewis and M L Garcia ldquoTherapeutic potential of venompeptidesrdquoNature ReviewsDrugDiscovery vol 2 no 10 pp 790ndash802 2003

[82] S I V Judge J M Lee C T Bever Jr and P M Hoff-man ldquoVoltage-gated potassium channels in multiple sclerosisoverview and new implications for treatment of central nervoussystem inflammation and degenerationrdquo Journal of Rehabilita-tion Research and Development vol 43 no 1 pp 111ndash122 2006

[83] L I Escobar J C Martınez-Tellez M Salas et al ldquoA voltage-gated K+ current in renal inner medullary collecting duct cellsrdquoThe American Journal of PhysiologymdashCell Physiology vol 286no 4 pp C965ndashC974 2004

[84] R Carrisoza-Gaytan C Salvador L M Satlin et al ldquoPotassiumsecretion by voltage-gated potassium channel Kv13 in the ratkidneyrdquoThe American Journal of Physiology - Renal Physiologyvol 299 no 1 pp F255ndashF264 2010

[85] K George Chandy M Cahalan M Pennington R S NortonHWulff andG A Gutman ldquoPotassium channels in T lympho-cytes toxins to therapeutic immunosuppressantsrdquo Toxicon vol39 no 9 pp 1269ndash1276 2001

[86] SMouhatG TeodorescuDHomerick et al ldquoPharmacologicalprofiling of Orthochirus scrobiculosus toxin 1 analogs with atrimmedN-terminal domainrdquoMolecular Pharmacology vol 69no 1 pp 354ndash362 2006

[87] I Kazama Y Maruyama and A Baba ldquoAmphipath-inducedplasma membrane curvature controls microparticle formationfrom adipocytes novel therapeutic implications for metabolicdisordersrdquoMedical Hypotheses vol 82 no 2 pp 196ndash198 2014

[88] I Kazama N Sasagawa and T Nakajima ldquoComplete remissionof human parvovirus B19 associated symptoms by loxoprofen inpatients with atopic predispositionsrdquo Case Reports in Medicinevol 2012 Article ID 703281 4 pages 2012

[89] I Kazama T Tamada and T Nakajima ldquoResolution of migra-tory pulmonary infiltrates by moxifloxacin in a patient withdual infection of Mycoplasma pneumoniae and Bordetella per-tussisrdquo Infezioni in Medicina vol 20 no 4 pp 288ndash292 2012

[90] I Kazama and T Nakajima ldquoDual infection of Mycoplasmapneumoniae and Chlamydophila pneumoniae in patients withatopic predispositions successfully treated by moxifloxacinrdquoInfezioni in Medicina vol 22 no 1 pp 41ndash46 2014

[91] I Kazama and T Nakajima ldquoA case of fitz-hugh-curtis syn-drome complicated by appendicitis conservatively treated withantibioticsrdquo Clinical Medicine Insights Case Reports vol 6 pp35ndash40 2013

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


Calcineurin

Kv13 channel

NFAT

IL-2 promoter

K+

(i) T cell proliferation

Ca2+

Ca2+-

[Ca2+] uarr

(ii) IL-2 production

Figure 1 Kv13-channel-induced activation pathway of T lym-phocytes Kv13-channels expressed in T lymphocytes facilitate thecalcium influx necessary to trigger the lymphocyte activation andproliferation The rise in the intracellular calcium concentrationstimulates the phosphatase calcineurin activity which then dephos-phorylates nuclear factor of activated T cells (NFAT) enabling itto accumulate in the nucleus and bind to the promoter of the geneencoding interleukin 2 (IL-2)

the recent in vitro and in vivo evidence that revealed thepharmacological properties of the channels this review alsofocuses on the novel therapeutic implications of targeting thechannels for the treatment of renal diseases

2 Increased Numbers of Leukocytes in RatKidneys with Renal Diseases

Previous studies have described several laboratory modelsof renal diseases including ligation of the renal arterybranches or unilateral ureter [23 24] ablation of renal massby surgery [25 26] toxic nephritis [27 28] and immuno-logically induced nephritis [29 30] In the developmentof glomerulonephritis inflammatory leukocytes are initiallyrecruited from the bone marrow and infiltrate into therenal interstitium to produce proinflammatory cytokines[9] Therefore the kidneys from rat models with toxic orimmunologically induced nephritis were characterized by themassive infiltration of T-lymphocytes ormacrophages [9 27ndash30] On the other hand in rat models with 56 nephrectomy(subtotal nephrectomy) the injured kidneys were mainly

characterized by severe glomerulosclerosis which was pri-marily caused by the renal hemodynamic changes such asthe increased glomerular pressure and the protein overload[31 32] However with the increase in the serum creatininethe kidneys from these subtotally nephrectomized rats wereadditionally characterized by diffuse interstitial fibrosis withthe involvement of leukocyte infiltration [7 8 33] In ratswith subtotal nephrectomy followed by longer recoveryperiods serum creatinine and blood urea nitrogen levelswere markedly elevated indicating advanced chronic renalfailure (CRF) [11 34] In CRF rat kidneys with 8-weekrecovery period the cortical interstitium was expanded withfibroedema (Figure 2(a)(B) versus Figure 2(a)(A)) and therewas some infiltration of small round cells among spindle-shaped fibroblasts (Figure 2(a)(E) versus Figure 2(a)(D)) At14 weeks in addition to diffuse fibrosis in the corticaland medullary interstitium (Figure 2(a)(C)) the numbers ofsmall round cells were dramatically increased in the corticalinterstitium (Figure 2(a)(F)) Since the cortical expressionof CD3 and ED-1 surface markers for T lymphocytes andmacrophages was markedly elevated [11] they were regardedas inflammatory leukocytes such as T lymphocytes andmacrophages By immunohistochemistry the CD3- or ED-1-positive small round cells were actually costained withKi-67 a marker of cellular proliferation (Figures 2(b)(A)and 2(b)(B)) The findings indicated that T lymphocytesand macrophages were proliferating prominently within thecortical interstitium of advanced CRF rat kidneys [34]

Recently Liu et al demonstrated that CD4+ T-lympho-cytes especially Th2 cells contributed to the progression ofrenal fibrosis in a rat model of unilateral ureteral obstruction(UUO) [35] In the development of the tubulointerstitialfibrosis in CRF rat kidneys previous studies demonstratedthat the inflammatory leukocytes were initially recruitedfrom the bone marrow and infiltrated into the renal inter-stitium to trigger the proliferation of fibroblasts [36] In thiscontext using the rat model of advanced CRF the recentstudies further demonstrated that the infiltrated leukocytesproliferated in situ in the cortical interstitium and thusdramatically increased their numbers [11 34]

3 Physiological Roles of Kv13-ChannelsExpressed in T-Lymphocytes

A variety of ion channels that are expressed in T lymphocytesinclude voltage-dependent K+-channels (Kv) Ca2+-activatedK+-channels (KCa) Ca2+ release-activated Ca2+-channels(CRAC) Mg2+-inhibited Ca2+-permeable current (MIC)channels and swelling-activated Clminus channels (Clswell) [37]Among them human T lymphocytes predominantly expressKv13-channels in their plasma membranes [1 2] In patch-clamp studies using thymus-derived murine lymphocytes(thymocytes) stepwise changes in the membrane potentialevoked membrane currents characteristic to Kv-channels[18 20 21 38 39] Since margatoxin a selective inhibitorof Kv13-channels almost totally abolished the currents inlymphocytes (Figure 3(a)) [38] these membrane currentswere identified as Kv13-channel currents The physiological


Sham

HampE


100120583m

CRF(8-week)


20120583m

(A) (B) (C)

(D) (E) (F)

(a)

CD3Ki-67 ED-1Ki-67

20120583m

(A) (B)

(b)






Before

500pA

50ms

100nMmargatoxin

+80mV

minus80mV

(a)

0

400

300

200

Before Washout

100

10120583Mbenidipine

Peak

curr

ent d

ensit

y (p

Ap

F)

Washout Before

0

100

200


Pulse

-end

curr

ent d

ensit

y (p

Ap

F)

50ms200pA

benidipine

(A)

(B) (C)

10120583M

(b)















HampE


100120583m

(A) (B)

(a)


Ki-67

20120583m

(A) (B)

(b)

12

0

40

80

10

0

50

IL-2

mRN

AG

APD

H m

RNA

ratio

IFN

-120574m

RNA

GA

PDH

mRN

A ra

tio

lowastlowast


(c)





100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)






Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Sham

HampE


100120583m

CRF(8-week)


20120583m

(A) (B) (C)

(D) (E) (F)

(a)

CD3Ki-67 ED-1Ki-67

20120583m

(A) (B)

(b)






Before

500pA

50ms

100nMmargatoxin

+80mV

minus80mV

(a)

0

400

300

200

Before Washout

100

10120583Mbenidipine

Peak

curr

ent d

ensit

y (p

Ap

F)

Washout Before

0

100

200


Pulse

-end

curr

ent d

ensit

y (p

Ap

F)

50ms200pA

benidipine

(A)

(B) (C)

10120583M

(b)















HampE


100120583m

(A) (B)

(a)


Ki-67

20120583m

(A) (B)

(b)

12

0

40

80

10

0

50

IL-2

mRN

AG

APD

H m

RNA

ratio

IFN

-120574m

RNA

GA

PDH

mRN

A ra

tio

lowastlowast


(c)





100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)






Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Before

500pA

50ms

100nMmargatoxin

+80mV

minus80mV

(a)

0

400

300

200

Before Washout

100

10120583Mbenidipine

Peak

curr

ent d

ensit

y (p

Ap

F)

Washout Before

0

100

200


Pulse

-end

curr

ent d

ensit

y (p

Ap

F)

50ms200pA

benidipine

(A)

(B) (C)

10120583M

(b)















HampE


100120583m

(A) (B)

(a)


Ki-67

20120583m

(A) (B)

(b)

12

0

40

80

10

0

50

IL-2

mRN

AG

APD

H m

RNA

ratio

IFN

-120574m

RNA

GA

PDH

mRN

A ra

tio

lowastlowast


(c)





100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)






Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



























HampE


100120583m

(A) (B)

(a)


Ki-67

20120583m

(A) (B)

(b)

12

0

40

80

10

0

50

IL-2

mRN

AG

APD

H m

RNA

ratio

IFN

-120574m

RNA

GA

PDH

mRN

A ra

tio

lowastlowast


(c)





100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)






Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



















100120583m

100120583m

CollagenIII

(C) (D)

(A) (B)

(a)

PAS


100120583m

(A) (B)

(b)






Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















Drugs 119873

















PAP-1Psora-4











IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















IL-2 promoter

Kv13

Macrolides

Statins

Benidipine (CCBs)

K+

channel

Calcineurin darr

NFAT darr



Ca2+-

[Ca2+] darr






References






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















review article roles of lymphocyte kv1.3-channels in the...

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