Abstract
Nuclear factor-κB (NF-κB) is one of the major families of transcription factors activated during the inflammatory response in asthma and chronic obstructive pulmonary disease. Inhibitory factor-κB kinase 2 (IKK-2) has been shown to play a pivotal role in cytokine-induced NF-κB activation in airway epithelium and in disease-relevant cells. Nevertheless, the potential toxicity of specific IKK-2 inhibitors may be unacceptable for oral delivery in chronic obstructive pulmonary disease. Therefore, local delivery to the lungs is an attractive alternative that warrants further exploration. Here, we describe potent and selective small-molecule IKK-2 inhibitors [8-(5-chloro-2-(4-methylpiperazin-1-yl)isonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide (PHA-408) and 8-(2-(3,4-bis(hydroxymethyl)-3,4-dimethylpyrrolidin-1-yl)-5-chloroisonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo-[g]indazole-3-carboxamide (PF-184)] that are competitive for ATP have slow off-rates from IKK-2 and display broad in vitro anti-inflammatory activities resulting from NF-κB pathway inhibition. Notably, PF-184 has been designed to have high systemic clearance, which limits systemic exposure and maximizes the effects locally in the airways. We used an inhaled lipopolysaccharide-induced rat model of neutrophilia to address whether inhibiting NF-κB activation locally within the airways would show anti-inflammatory effects in the absence of systemic exposure. PHA-408, a low-clearance compound previously shown to be efficacious orally in a rodent model of arthritis, dose-dependently attenuated inhaled lipopolysaccharide-induced cell infiltration and cytokine production. Interestingly, PF-184 produced comparable dose-dependent anti-inflammatory activity by intratracheal administration and was as efficacious as intratracheally administered fluticasone propionate (fluticasone). Together, these results support the potential therapeutic utility of IKK-2 inhibition in inflammatory pulmonary diseases and demonstrate anti-inflammatory efficacy of an inhaled IKK-2 inhibitor in a rat airway model of neutrophilia.
Footnotes
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.108.147538.
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ABBREVIATIONS: COPD, chronic obstructive pulmonary disease; PHA-408, 8-(5-chloro-2-(4-methylpiperazin-1-yl)isonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide; PF-184, 8-(2-(3,4-bis(hydroxymethyl)-3,4-dimethylpyrrolidin-1-yl)-5-chloroisonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide; NF-κB, nuclear factor-κB; IκB, inhibitory factor-κB; IKK, IκB kinase; LPS, lipopolysaccharide; ELISA, enzyme-linked immunosorbent assay; IL, interleukin; TNF-α, tumor necrosis factor-α; MIP, macrophage inflammation protein; Gro-α, growth-related oncogene-α; MCP-1, monocyte chemotactic protein-1; PMN, polymorphonuclear; PBMC, peripheral blood mononuclear cell; DMEM, Dulbecco's modified Eagle's medium; BAL, bronchial alveolar lavage; IT, intratracheal; rh, recombinant human; RASF, rheumatoid arthritic synovial fibroblast; SC-514, 3-amino-5-(thiophen-3-yl)thiophene-2-carboxamide); CSC, cigarette smoke condensate; FBS, fetal bovine serum; GM-CSF, granulocyte-macrophage colony-stimulating factor; ANOVA, analysis of variance; PGE2, prostaglandin E2; PHA-357, 8-(5-chloro-2-(4-methylpiperazin-1-yl)isonicotinamido)-1-(pyridin-4-yl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide; UK-436303, N-(5-methyl-1H-pyrazol-3-yl)-2-(2-methylpyrrolidin-1-yl)pyrido[2,3-d)pyrimidin-4-amine; BAY-117082, (E)-3[(4-methylphenylsulfonyl]-2-propenenitrile.
- Received October 20, 2008.
- Accepted May 26, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
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