NS6180, a new K(Ca) 3.1 channel inhibitor prevents T-cell activation and inflammation in a rat model of inflammatory bowel disease.
OBJECTIVE
The K(Ca) 3.1 channel is a potential target for therapy of immune disease. We identified a compound from a new chemical class of K(Ca) 3.1 inhibitors and assessed in vitro and in vivo inhibition of immune responses.


METHODS
We characterized the benzothiazinone NS6180 (4-[[3-(trifluoromethyl)phenyl]methyl]-2H-1,4-benzothiazin-3(4H)-one) with respect to potency and molecular site of action on K(Ca) 3.1 channels, selectivity towards other targets, effects on T-cell activation as well as pharmacokinetics and inflammation control in colitis induced by 2,4-dinitrobenzene sulfonic acid, a rat model of inflammatory bowel disease (IBD).


RESULTS
NS6180 inhibited cloned human K(Ca) 3.1 channels (IC(50)  = 9 nM) via T250 and V275, the same amino acid residues conferring sensitivity to triarylmethanes such as like TRAM-34. NS6180 inhibited endogenously expressed K(Ca) 3.1 channels in human, mouse and rat erythrocytes, with similar potencies (15-20 nM). NS6180 suppressed rat and mouse splenocyte proliferation at submicrolar concentrations and potently inhibited IL-2 and IFN-γ production, while exerting smaller effects on IL-4 and TNF-α and no effect on IL-17 production. Antibody staining showed K(Ca) 3.1 channels in healthy colon and strong up-regulation in association with infiltrating immune cells after induction of colitis. Despite poor plasma exposure, NS6180 (3 and 10 mg·kg(-1)  b.i.d.) dampened colon inflammation and improved body weight gain as effectively as the standard IBD drug sulfasalazine (300 mg·kg(-1)  q.d.).


CONCLUSIONS
NS6180 represents a novel class of K(Ca) 3.1 channel inhibitors which inhibited experimental colitis, suggesting K(Ca) 3.1 channels as targets for pharmacological control of intestinal inflammation.
NeuroSearch A/S, Ballerup, Denmark.
D
D
Strøbæk
D T
DT
Brown
D P
DP
Jenkins
Y-J
YJ
Chen
N
N
Coleman
Y
Y
Ando
P
P
Chiu
S
S
Jørgensen
J
J
Demnitz
H
H
Wulff
P
P
Christophersen
D000818:Animals; D004139:Dinitrofluorobenzene / Q000031:analogs & derivatives; D004195:Disease Models, Animal; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000188:drug therapy; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy* / Q000276:immunology; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000502:physiology; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D026902:Potassium Channel Blockers / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D013843:Thiazines / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*
C581707:4-((3-(trifluoromethyl)phenyl)methyl)-2H-1,4-benzothiazin-3(4H)-one; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496925:Kcnn4 protein, mouse; D026902:Potassium Channel Blockers; D013843:Thiazines; C045305:2,4-dinitrofluorobenzene sulfonic acid; D004139:Dinitrofluorobenzene