The beta2 integrin leukocyte function antigen-1 (LFA-1) has an important role in the pathophysiology of inflammatory and autoimmune diseases. Here we report that statin compounds commonly used for the treatment of hypercholesterolemia selectively blocked LFA-1-mediated adhesion and costimulation of lymphocytes. This effect was unrelated to the statins' inhibition of 3-hydroxy-3-methylglutaryl coenzyme-A reductase; instead it occurred via binding to a novel allosteric site within LFA-1. Subsequent optimization of the statins for LFA-1 binding resulted in potent, selective and orally active LFA-1 inhibitors that suppress the inflammatory response in a murine model of peritonitis. Targeting of the statin-binding site of LFA-1 could be used to treat diseases such as psoriasis, rheumatoid arthritis, ischemia/reperfusion injury and transplant rejection.

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There is a pressing need for immunosuppressants with an improved safety profile. The search for novel approaches to blocking T-cell activation led to the development of the selective protein kinase C (PKC) inhibitor AEB071 (sotrastaurin). In cell-free kinase assays AEB071 inhibited PKC, with K i values in the subnanomolar to low nanomolar range. Upon T-cell stimulation, AEB071 markedly inhibited in situ PKC catalytic activity and selectively affected both the canonical nuclear factor-B and nuclear factor of activated T cells (but not activator protein-1) transactivation pathways. In primary human and mouse T cells, AEB071 treatment effectively abrogated at low nanomolar concentration markers of early T-cell activation, such as interleukin-2 secretion and CD25 expression. Accordingly, the CD3/CD28 antibody-and alloantigen-induced T-cell proliferation responses were potently inhibited by AEB071 in the absence of nonspecific antiproliferative effects. Unlike former PKC inhibitors, AEB071 did not enhance apoptosis of murine T-cell blasts in a model of activation-induced cell death. Furthermore, AEB071 markedly inhibited lymphocyte function-associated antigen-1-mediated T-cell adhesion at nanomolar concentrations. The mode of action of AEB071 is different from that of calcineurin inhibitors, and AEB071 and cyclosporine A seem to have complementary effects on T-cell signaling pathways.Phosphorylation of serine, threonine, and tyrosine residues is a primary mechanism for regulating protein function in eukaryotic cells. Protein kinases, the enzymes that catalyze these reactions, regulate essentially all cellular processes and have thus emerged as therapeutic targets for many human diseases. However, nearly all protein kinase inhibitors target the ATP binding site. For this reason, design of inhibitors that selectively target even a subset of the approximately 570 related human protein kinase domains continues to be a daunting challenge. Nevertheless, small-molecule inhibitors of Abelson tyrosine kinase and epidermal growth factor receptor have been recently developed into clinically useful anticancer drugs (for review, see Medinger and Drevs, 2005).The protein kinase C (PKC) family of serine/threonine kinases plays a central role in the adaptive immune system. PKC can be grouped into three categories according to the

In vivo phosphorylation of FTY720 (1) in rats and humans resulted exclusively in the biologically active (S)-configured enantiomer, which was proven by an ex vivo o-phthaldialdehyde derivatization protocol especially elaborated for phosphates of 1. Starting from the prochiral amino alcohol 1, racemic and enantiomerically pure phosphates of 1 were synthesized. Pure enantiomers were obtained after purification of a partially protected key intermediate on an enantioselective support. The absolute stereochemistry was determined by X-ray diffraction.

Integrins are a family of ␣/␤ heterodimeric cell surface receptors that mediate cell-cell and cell-extracellular matrix interactions. They are involved in various pathophysiological processes leading to acute and chronic disease states (1). Lymphocyte function-associated antigen-1 (LFA-1, 1 ␣ L ␤ 2 , CD11a/ CD18) belongs to the ␤ 2 integrin subfamily and is constitutively expressed on all leukocytes. LFA-1 is involved in leukocyte extravasation into tissue and T cell costimulation (2, 3). Several studies underscore the importance of LFA-1 in the pathophysiology of inflammatory and autoimmune diseases (e.g. ischemia/reperfusion injury (4), rheumatoid arthritis (5), psoriasis (6), and transplant rejection (7)). The major ligands of LFA-1 are three members of the immunoglobulin superfamily, intercellular adhesion molecules 1, 2, and 3 (ICAM-1, -2, and -3, respectively) (2).Central to ligand binding by LFA-1 is an inserted domain of 200 amino acids at the N terminus of the ␣ L subunit, the so called I domain (8). This LFA-1 I domain is highly homologous to I domains displayed on other integrin ␣ subunits (9). Threedimensional structures of I domains reveal that they adopt a dinucleotide-binding fold and contain a cation binding site designated the metal ion-dependent adhesion site (MIDAS). There is strong evidence that the metal ion of the MIDAS is coordinated by an acidic residue from ICAM and thus directly participates in ligand binding (9). The LFA-1 I domain is inserted between the ␤ sheets 2 and 3 of a seven-bladed putative ␤-propeller region on the ␣ L subunit (10).There is strong evidence that integrin ␤ subunits contain regions structurally homologous to the I domains, the so-called I-like domains (9, 11). The existence of such I-like domains was recently confirmed by the crystal structure of the extracellular segment of the integrin ␣ V ␤ 3 (12). The I-like domain of the LFA-1 ␤ 2 subunit is predicted to contact the putative ␤ propeller of the ␣ L subunit near ␤ sheets 2 and 3 (13). A recent study suggests that the I-like domain has a regulatory role rather than a direct role in ligand binding (14).As described for other integrins, the ligand binding activity of LFA-1 is tightly regulated (1, 15). LFA-1 is expressed on leukocytes in an inactive state and can be rapidly activated by cations or by intracellular signals (2, 15). Receptor clustering and conformational changes are proposed to be the major mechanisms by which LFA-1 is converted from a low to a high affinity form (15). Several studies provide strong evidence that in particular the C-terminal helix of the I domain plays an important role in the activation process. It has been recently demonstrated that LFA-1 can be locked in an open ligand binding and a closed nonbinding conformation by mutational introduction of disulfide bonds between the C-terminal helix and a central ␤ sheet of the I domain (16). The positions of the disulfide bonds were modeled according to the crystal structures of Mac-1 (␣ M ␤ 2 , CD11b/CD18) and VLA-2 (␣ 2 ␤ 1 , CD49b/ CD29...