title: Ligation of CD40 activates interleukin 1beta-converting enzyme (caspase-1) activity in vascular smooth muscle and endothelial cells and promotes elaboration of active interleukin 1beta.
abstract: Inflammation contributes to a variety of arterial diseases including atherosclerosis. Interleukin 1beta (IL-1beta) in its activated mature 17-kDa form may mediate aspects of vascular inflammation. As shown previously, human vascular wall cells, such as smooth muscle cells (SMC), express the IL-1beta precursor upon stimulation and the IL-1beta-converting enzyme (ICE) constitutively but do not produce mature IL-1beta or express ICE activity. How SMC, the most numerous cell type in arteries, may release active IL-1beta has therefore remained a perplexing problem. We report here that stimulation of human vascular SMC and endothelial cells (EC) through CD40 ligand, a mediator recently localized in human atheroma, induced elaboration of the IL-1beta precursor as well as activation of cell-associated ICE. In addition to the constitutively expressed 45- and 30-kDa immunoreactive ICE proteins, vascular cells incubated with recombinant human CD40 ligand (rCD40L) (but not IL-1 or TNF) showed an increase of a 20-kDa immunoreactive ICE protein by Western blot analysis. Furthermore, SMC and EC stimulated through rCD40L processed recombinant human IL-1beta precursor (pIL-1beta), generating a cleavage product of approximately 17 kDa. Appearance of both the 20-kDa immunoreactive ICE protein and pIL-1beta processing activity required at least 6 h of stimulation with 0.3 or 1.0 microg/ml rCD40L, respectively, and was inhibited by pre-incubation of the ligand with an anti-CD40L antibody. Stimulation of vascular SMC and EC through rCD40L resulted in the release of biologically active IL-1beta, indicating processing of the native IL-1beta precursor induced by the ligand. These findings establish a novel mechanism of IL-1beta activation in human vascular cells and, moreover, indicate a new pathway of ICE-activation, which could participate in inflammatory aspects of atherogenesis and other disease states.
authors.affiliation: Vascular Medicine and Atherosclerosis Unit, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: U
authors.initials: U
authors.lastname: Schönbeck
authors.forename: F
authors.initials: F
authors.lastname: Mach
authors.forename: J Y
authors.initials: JY
authors.lastname: Bonnefoy
authors.forename: H
authors.initials: H
authors.lastname: Loppnow
authors.forename: H D
authors.initials: HD
authors.lastname: Flad
authors.forename: P
authors.initials: P
authors.lastname: Libby
mesh_terms: D019013:CD40 Antigens / Q000502:physiology; D023201:CD40 Ligand; D020170:Caspase 1; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000201:enzymology*; D004789:Enzyme Activation; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D019013:CD40 Antigens; D007375:Interleukin-1; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D023201:CD40 Ligand; D003546:Cysteine Endopeptidases; D020170:Caspase 1