NS6180, a new KCa3.1 blocker, inhibits T‐cell activation and dampens inflammation in a rat model of inflammatory bowel disease

Autor: Heike Wulff, Palle Christophersen, Dorte Strøbæk, David T. Brown, Paul David Jenkins, Joachim Demnitz, Peter Chiu, Susanne Jørgensen
Rok vydání: 2012
Předmět:
Zdroj: The FASEB Journal. 26
ISSN: 1530-6860
0892-6638
DOI: 10.1096/fasebj.26.1_supplement.695.12
Popis: The calcium-activated potassium channel KCa3.1 plays an important role in the activation of T- and B-cells, mast cells, macrophages and microglia by providing part of the hyperpolarizing driving force for the calcium entry that is necessary for orchestrating cellular proliferation, migration and cytokine production. Using a high-throughput assay measuring calcium-activated thallium influx in HEK293 cells stably expressing the human KCa3.1 channel, we identified the benzothiazinone NS6180 (4-[[3-(trifluoromethyl)phenyl]methyl]-2H-1,4-benzothiazin-3(4H)-one), which belongs to a new chemical class of small molecule KCa3.1 blockers. In whole-cell patch-clamp experiments NS6180 inhibited KCa3.1 with an IC50 of 11 nM via interaction with the amino acids T250 and V275, the same residues conferring sensitivity to triarylmethanes, like TRAM-34 and clotrimazole. NS6180 blocked the classic Gardos channel, the endogenous KCa3.1 channel in erythrocytes, with nearly identical potencies (15-20 nM) in human, mouse and rat erythrocytes as measured by CCCP-reported hyperpolarizations initiated by the calcium ionophore A23187. NS6180 exhibited excellent selectivity over other ion channels and suppressed rat and mouse splenocyte proliferation at submicrolar concentrations, whereas no effect was observed with splenocytes from KCa3.1-/- mice. Additionally, NS6180 potently inhibited IL-2 and INF-γ production, but exerted smaller effects on IL-4 and TNF-α and no effect on IL-17 production. When administered orally to rats at 3 and 10 mg/kg twice daily, NS6180 inhibited the development of DNBS-induced colitis and macroscopic disease indices (i.e. colon and body weight development) as effectively as the benchmark therapeutic sulfasalazine at 300 mg/kg. Based on these results we suggest benzothiazinone-type KCa3.1 blockers as novel anti-inflammatory tool compounds and potential drugs.
Databáze: OpenAIRE
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