title: Rapid TNFR1-dependent lymphocyte depletion in vivo with a selective chemical inhibitor of IKKbeta.
abstract: The transcription factor NF-kappaB plays a central role in regulating inflammation and apoptosis, making it a compelling target for drug development. We identified a small molecule inhibitor (ML120B) that specifically inhibits IKKbeta, an Ikappa-B kinase that regulates NF-kappaB. IKKbeta and NF-kappaB are required in vivo for prevention of TNFalpha-mediated apoptosis. ML120B sensitized mouse bone marrow progenitors and granulocytes, but not mature B cells to TNFalpha killing in vitro, and induced apoptosis in vivo in the bone marrow and spleen within 6 hours of a single oral dose. In vivo inhibition of IKKbeta with ML120B resulted in depletion of thymocytes and B cells in all stages of development in the bone marrow but did not deplete granulocytes. TNF receptor-deficient mouse thymocytes and B cells were resistant to ML120B-induced depletion in vivo. Surprisingly, surviving bone marrow granulocytes expressed TNFR1 and TNFR2 after dosing in vivo with ML120B. Our results show that inhibition of IKKbeta with a small molecule in vivo leads to rapid TNF-dependent depletion of T and B cells. This observation has several implications for potential use of IKKbeta inhibitors for the treatment of inflammatory disease and cancer.
authors.affiliation: Millennium Pharmaceuticals Inc, 35 Landsdowne St, Cambridge, MA 02139, USA.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nagashima
authors.forename: Vito G
authors.initials: VG
authors.lastname: Sasseville
authors.forename: Danyi
authors.initials: D
authors.lastname: Wen
authors.forename: Andrew
authors.initials: A
authors.lastname: Bielecki
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
authors.forename: Chris
authors.initials: C
authors.lastname: Simpson
authors.forename: Ethan
authors.initials: E
authors.lastname: Grant
authors.forename: Michael
authors.initials: M
authors.lastname: Hepperle
authors.forename: Gerry
authors.initials: G
authors.lastname: Harriman
authors.forename: Bruce
authors.initials: B
authors.lastname: Jaffee
authors.forename: Tim
authors.initials: T
authors.lastname: Ocain
authors.forename: Yajun
authors.initials: Y
authors.lastname: Xu
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Fraser
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001402:B-Lymphocytes / Q000187:drug effects; D001854:Bone Marrow Cells / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006098:Granulocytes / Q000187:drug effects / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors*; D008212:Lymphocyte Depletion / Q000379:methods*; D051379:Mice; D018345:Mice, Knockout; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000172:deficiency / Q000502:physiology*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000172:deficiency / Q000502:physiology; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha; C069521:recombinant human tumor necrosis factor-binding protein-1; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse