INH14 is a novel inhibitor of the IKKα/β-dependent TLR inflammatory response (IC50s: 8.97/3.59 μM for IKKα/IKKβ).

Overexpression of proteins that are part of the TLR2 pathway in cells treated with INH14 indicated that the target lay downstream of the complex TAK1/TAB1. INH14 decreased IkBα degradation in cells activated by lipopeptide (TLR2 ligand). The kinases IKKα and/or IKKβ were the targets of INH14, which was confirmed with kinase assays (IC50 IKKα=8.97?μM; IC50 IKKβ=3.59?μM).

In vivo experiments showed that INH14 decreased TNFα formed after lipopeptide-induced inflammation, and treatment of ovarian cancer cells with INH14 led to a reduction of NF-kB constitutive activity and a reduction in the wound-closing ability of these cells.

IKKα and IKKβ kinase assays (ADP-GloTM 109 kinase assay) were purchased from Promega and used following the manufacturer′s instructions. The quantification of the ADP produced in the reactions (chemiluminescence) was measured with a Victor plate reader. IKKα (15 ng per reaction) or IKKβ (20 ng per reaction) were incubated with ATP (50 μM or 25 μM, respectively) and substrate-peptide (0.2 ng/ml) in the presence of vehicle or increasing concentrations of INH14 at room temperature for one hour.

Human primary monocytes (8 x 10^4 cells/well) were seeded and incubated overnight with the compound, media control, or SDS (0.02%). Then, the tetrazolium salt WST-8 was added, and the cells were incubated for one additional hour at 37°C. During this period, the dehydrogenase activity of viable cells led to the production of the coloured product (formazan). The cell viability was measured with a Victor plate reader as an increase in the absorbance at 450 nm.

8-week old, male, pathogen-free C57BL/6J mice were maintained at the animal facility (12 h light/dark cycle; standard rodent chow and water available ad libitum). For lipopeptide-induced inflammation, 5 μg/g of INH14 or vehicle were administered intraperitoneally. After one hour, P2 (2.5 μg/g) was injected and 25 μl of tail vein blood were collected at that time point (0 h) and 2 h after. The blood was centrifuged at 5 x 10^3 x g, and the supernatant frozen at -20 °C until further cytokine measurement by ELISA.