title: Ro 32-0432, a selective and orally active inhibitor of protein kinase C prevents T-cell activation.
abstract: Several lines of circumstantial evidence support the assumption that protein kinase C (PKC) activation together with elevated levels of cytosolic Ca++ are necessary for T-cell activation and proliferation in response to a physiological stimulus, i.e., MHC class II restricted antigen presentation. By using a potent, cell-permeable and selective inhibitor of PKC, Ro 32-0432, we have tested this hypothesis. Ro 32-0432 inhibits interleukin-2 (IL-2) secretion, IL-2 receptor expression in, and proliferation of, peripheral human T-cells stimulated with phorbol ester together with phytohemagglutin or anti-CD3, but does not inhibit IL-2 induced proliferation in cells already stimulated to express IL-2 receptors. Proliferation of the influenza peptide antigen HA 307-319-specific human T-cell clone (HA27) after exposure to antigen-pulsed autologous presenting cells was also inhibited by Ro 32-0432. Oral administration of Ro 32-0432 inhibited subsequent phorbol ester-induced edema in rats demonstrating the systemic efficacy of the compound to inhibit PKC-driven responses. Induction of more physiologically T-cell driven responses such as host vs. graft responses and the secondary paw swelling in adjuvant-induced arthritis were also inhibited by Ro 32-0432. These data demonstrate the crucial role for PKC in T-cell activation and that selective p.o. bioavailable PKC inhibitors are efficacious in preventing T-cell driven chronic inflammatory responses in vivo. Inhibition of PKC represents an important mechanistic approach to prevent T-cell activation and compounds of this class may have important therapeutic applicability to chronic inflammatory and autoimmune diseases.
authors.affiliation: Roche Research Centre, Welwyn Garden City, Herts, United Kingdom.
authors.forename: A M
authors.initials: AM
authors.lastname: Birchall
authors.forename: J
authors.initials: J
authors.lastname: Bishop
authors.forename: D
authors.initials: D
authors.lastname: Bradshaw
authors.forename: A
authors.initials: A
authors.lastname: Cline
authors.forename: J
authors.initials: J
authors.lastname: Coffey
authors.forename: L H
authors.initials: LH
authors.lastname: Elliott
authors.forename: V M
authors.initials: VM
authors.lastname: Gibson
authors.forename: A
authors.initials: A
authors.lastname: Greenham
authors.forename: T J
authors.initials: TJ
authors.lastname: Hallam
authors.forename: W
authors.initials: W
authors.lastname: Harris
mesh_terms: D000284:Administration, Oral; D000595:Amino Acid Sequence; D000818:Animals; D001169:Arthritis, Experimental / Q000517:prevention & control; D005260:Female; D007211:Indoles / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011758:Pyrroles / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D007211:Indoles; D011758:Pyrroles; C085989:Ro 32-0432; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C