Báo cáo khoa học: Therapeutic targeting of molecules involved in leukocyte–endothelial cell interactions potx

MINIREVIEW Therapeutic targeting of molecules involved in leukocyte–endothelial cell interactions Nicole C. Kaneider 1 , Andrew J. Leger 1,2 and Athan Kuliopulos 1,2,3 1 Molecular Oncology Research Institute, Tufts-New England Medical Center, Boston, MA, USA 2 Department of Medicine, Tufts University School of Medicine, Boston, MA, USA 3 Department of Biochemistry, Tufts University School of Medicine, Boston, MA, USA One of the key characteristics of inflammation is the recruitment of leukocytes to the site of tissue injury. There are three major subsets of leukocytes with migratory capacity that are involved in inflammation: neutrophils, monocytes ⁄ macrophages and lymphocytes. Quiescent endothelium acts as a barrier between the circulating white blood cells and the underlying sub- endothelial tissue. In response to inflammatory stimuli, endothelial cells undergo a phenotypic change and act- ively facilitate the recruitment and transmigration of leukocytes to the site of inflammation. The neutrophil is a short-lived phagocyte that plays an essential role in the defense against microorganisms, as witnessed by the life-threatening infections that occur in patients with neutropenia or in those with leu- kocyte defects. Neutrophils are the most abundant leu- kocyte type in humans, and accumulate, within hours, at sites of acute inflammation. Once at the site of injury, neutrophils secrete a variety of destructive enzymes, such as myeloperoxidase, elastase, matrix metalloproteases and cathepsins. In the absence of proper feedback mechanisms, the destructive power of neutrophils contributes significantly to the pathogene- sis of numerous diseases. Neutrophils have been impli- cated in the progression of many inflammatory diseases, including sepsis, the systemic inflammatory response syndrome (Fig. 1), the acute respiratory dis- tress syndrome, chronic obstructive pulmonary disease and others (Table 1). Few currently available therapeu- tic agents, including corticosteroids, effectively down- regulate the pro-inflammatory activity of neutrophils. Monocytes are long-lived leukocytes and play a crit- ical role in the orchestration of the inflammatory response. Monocytes migrate from the blood into Keywords endothelium; inflammatory diseases; leukocytes; therapeutic targets Correspondence A. Kuliopulos, Tufts-NEMC, 750 Washington St., Box 7510, Boston, MA 02111, USA Fax: +1 617 636 7855 Tel: +1 617 636 8482 E-mail: athan.kuliopulos@tufts.edu (Received 15 May 2006, accepted 12 July 2006) doi:10.1111/j.1742-4658.2006.05441.x Inflammation is traditionally viewed as a physiological reaction to tissue injury. Leukocytes contribute to the inflammatory response by the secretion of cytotoxic and pro-inflammatory compounds, by phagocytotic activity and by targeted attack of foreign antigens. Leukocyte accumulation in tis- sues is important for the initial response to injury. However, the overzeal- ous accumulation of leukocytes in tissues also contributes to a wide variety of diseases, such as atherosclerosis, chronic inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, vasculitis, systemic inflammatory response syndrome, juvenile diabetes and psoriasis. Many therapeutic inter- ventions target immune cells after they have already migrated to the site of inflammation. This review addresses different therapeutic strategies, used to reduce or prevent leukocyte–endothelial cell interactions and communica- tion, in order to limit the progression of inflammatory diseases. Abbreviations GPCR, G protein-coupled receptor; ICAM-1, intercellular adhesion molecule-1; IL, interleukin; LFA-1, lymphocyte function-associated antigen-1; PAR, protease activated receptor; PSGL-1, P-selectin glycoprotein ligand-1; S1P, sphingosine-1-phosphate; VCAM-1, vascular cell adhesion molecule-1. 4416 FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS various tissues where they transform into macrophag- es. Cells of the mononuclear phagocytotic system have been linked to a variety of inflammatory diseases, in particular to atherosclerosis, where macrophages trans- form into foam cells and mediate atherosclerotic pla- que formation (Fig. 2). Because macrophages produce a wide range of biologically active molecules involved in both beneficial and detrimental outcomes in inflam- mation, therapeutic interventions that target macro- phages and their products may be a fruitful avenue to control chronic inflammatory conditions. Lymphocytes provide acquired immunity and repre- sent the collective memory of the immune system. Naı ¨ ve lymphocytes reside mainly in lymphoid organs, Fig. 1. Cell surface molecules as potential targets in systemic inflammatory response syndrome as a neutrophil-driven disease. Table 1. Targeting cell surface molecules of predominant cell types in inflammatory diseases. ARDS, acute respiratory distress syndrome; CLA, cutaneous lymphocyte-associated antigen; COPD, chronic obstructive pulmonary disease; GPCR, G protein-coupled receptor; LFA-1, lymphocyte function-associated antigen-1; LTB4, leukotriene B4; PAFR, platelet activating factor receptor; PSGL-1, P-selectin glycoprotein ligand-1; SIRS, systemic inflammatory response syndrome; VLA-4, very late antigen-4. Predominant cell type Neutrophil Monocyte ⁄ macrophage Lymphocyte Disease Ischemia-reperfusion injury, SIRS, COPD, ARDS, cystic fibrosis, osteomyelitis, Goodpasture syndrome, immune complex-mediated vasculitides, pyelonephritis. glomerulonephritis, gout Atherosclerosis, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, COPD, asthma Multiple sclerosis, rheumatoid arthritis, psoriasis, inflammatory bowel disease, type-1 diabetes, allograft rejection, lupus, asthma, atopic dermatitis Integrin LFA-1, Mac-1 VLA-4 VLA-1, VLA-2, VLA-4, LFA-1 Selectin and ligand L-selectin, PSGL-1 PSGL-1 L-selectin, PSGL-1, CLA GPCR CXCR1, CXCR2, LTB4, PAR4 CCR1, CCR2, CXCR2 CCR1, CCR2, CXCR2, CCR5, CXCR3, CCR4, CCR10, PAFR, LTB4 N. C. Kaneider et al. Targeting leukocyte–endothelial cell interactions FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS 4417 whereas effector and memory lymphocytes move into inflamed tissue when attracted by an array of chemo- kines [1,2]. T lymphocytes play central roles in adap- tive immune responses against protein antigens. Two major B-cell subsets have been described to date [3,4]. B1 cells produce low affinity IgM that is reactive to a limited number of highly conserved microbial and host antigens. B2 cells are the most numerous type of B cells found in tissues and lymphoid organs, and their major role is to produce antibodies for the defense against extracellular bacteria [5]. B2 cells undergo clonal expansion, isotype switching and develop into memory cells, and can process and present antigens to T cells to amplify or regulate adaptive immune responses. A central feature of inflammation is the ingress of circulating leukocytes across the endothelium and underlying basement membranes into the affected tis- sue. Excessive, unregulated and sustained activation of the endothelium that occurs during severe inflamma- tory processes leads to endothelial dysfunction and damage. Exposure of endothelial cells to pro-inflam- matory mediators results in an up-regulation of E- and P-selectin, vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and other adhesion molecules which mediate leukocyte rolling and firm adhesion. Local chemokines secreted by the endothelium or subendothelial components direct leukocyte chemotaxis across the vascular intima. Emerging therapeutic strategies aimed at controlling inflammation interfere at various stages of the multi- step recruitment cascade of leukocytes. The function of inflammatory adhesion molecules can be modula- ted by competitive blockade, altered surface expres- sion of ligands and adhesion molecules on the cell surface, or by inhibition of chemokine G protein- coupled receptor (GPCR) signaling [6]. Several anti- inflammatory drugs indirectly inhibit components involved in leukocyte–endothelial cell interactions. For example, compounds that block interleukin (IL)-1 or tumor necrosis factor-a have potent effects on the expression of E-selectin, VCAM and other cell adhe- sion molecules on endothelial cells [7,8]. Corticoster- oids, nonsteroidal anti-inflammatory drugs or statins have also been shown to decrease the expression of adhesion molecules and pro-inflammatory chemo- kines, by nuclear factor-jB dependent gene transcrip- tion [9–11] (Fig. 3). Fig. 2. Cell surface molecules as potential targets in atherosclerosis as a macrophage-driven disease. Targeting leukocyte–endothelial cell interactions N. C. Kaneider et al. 4418 FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS Selectins Selectins consist of three members of C-type lectins that bind sialyl-Lewis X carbohydrate ligands, such as P-selectin glycoprotein ligand-1 (PSGL-1) [12]. P-selec- tin is stored in granules of endothelial cells and plate- lets and it translocates to the cell surface following exposure to inflammatory stimuli. E-selectin is exclu- sively expressed by endothelial cells, and L-selectin is expressed on many subclasses of leukocytes [13]. The interaction of P- and E-selectin with leukocyte PSGL-1 and other sialyl Lewis-X glycoconjugates initiates the attachment, rolling and homing of leukocytes on endo- thelium. Conversely, L-selectin on leukocytes binds to endothelial ligands containing sulfated sialyl-Lewis X like molecules. Inhibiting leukocyte rolling by blocking selectins affects the accumulation of leukocytes in many experi- mental settings [14,15]. Blocking selectin activity with humanized antibodies has been studied extensively in several clinical disorders. Initial preclinical studies in asthma, psoriasis, ischemia-reperfusion injury, or myocardial infarction were promising; however, the results of clinical trials with mAbs against E-, P- and L-selectins were disappointing [6]. Attention was switched to the common ligand of all selectins, namely sialyl-Lewis X, as a broad-based therapeutic target [15]. Outcomes from human trials using mimet- ics of sialyl-Lewis X or small molecule inhibitors of selectins have been more promising than those using selectin-directed antibodies [16]. The synthetic inhib- itor bimosiamose (Table 2), a sialyl-Lewis X mimetic, improved psoriasis manifestations and allergen-indu- ced asthma in humans [17,18]. Moreover, a new class of selectin inhibitors, called efomycines, found as a fermentation by-product of Streptomyces BS1261, have shown promising results in mouse models of skin inflammation [19]. Fig. 3. Cell surface molecules as potential targets in inflammatory bowel disease as a lymphocyte-driven disease. N. C. Kaneider et al. Targeting leukocyte–endothelial cell interactions FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS 4419 Integrins Integrins constitute a family of 24 heterodimers with a- and b-subunits whose ligand-binding activity is regulated by conformational changes, transcriptional induction and redistribution from intracellular pools [20]. Integrins mediate cell–cell, cell–extracellular matrix and cell–patho- gen interactions by binding to distinct, but overlapping, Table 2. Selectin, integrin and GPCR antagonists in clinical and preclinical studies. COPD, chronic obstructive pulmonary disease; IBD, inflammatory bowel disease; MS, multiple sclerosis; S1PR, sphingosine-1-phosphate receptor; SAE, severe adverse effect; SIRS, systemic inflammatory response syndrome. Target Drug Disease Mechanism of action Stage of development P-, E- and L-selectin Bimosiamose Asthma, psoriasis Sialyl-Lewis X analogue Phase II P-, E- and L-selectin OC229648 Mouse model of peritonitis Sialyl-Lewis X analogue Preclinical P-, E- and L-selectin Efomycine Mouse psoriasis Sialyl-Lewis X analogue Preclinical P- and E-selectin HuEP5C7 Baboon stroke model Blocking antibody Preclinical E-selectin CDP850 Psoriasis Blocking antibody Phase II P-, E- and L-selectin CY1503 Ischemia-reperfusion injury in lambs Sialyl-Lewis X analogue Preclinical P- and L-selectin rPSGL-Ig Myocardial infarction Antibody Phase II (stopped) P-selectin CY1747 Ischemia-reperfusion injury Blocking antibody Preclinical CD18 Rovelizumab Myocardial infarction, MS, stroke Blocking antibody Phase II in MS and stroke (stopped, no effects) CD18 Erlizumab Myocardial infarction Blocking antibody Phase II (stopped, no effects) CD11a Odulimomab Transplant rejection, mouse model of atopic dermatitis Blocking antibody Phase III, preclinical in dermatitis CD11a Efalizumab Psoriasis Blocking antibody Approved for psoriasis CD49d Natalizumab MS, Crohn’s disease Blocking antibody Phase III (halted because of SAEs) a4b1 TR14035 Asthma Small peptide antagonist Phase II a4b7 MLN02 Ulcerative colitis Blocking antibody Phase II ICAM-1 ISIS2302 IBD, rheumatoid Antisense nucleotide Phase III in rheumatoid Enlimomab arthritis, psoriasis arthritis and Crohn’s disease Phase II in ulcerative colitis and in psoriasis CXCR2 SB 225002 COPD Pyrimidine-based receptor antagonist Phase I CXCR2 SB-332235 COPD Pyrimidine-based receptor antagonist Preclinical CXCR1 and CXCR2 Repertaxin Ischemia-reperfusion primary graft dysfunction Small molecule inhibitor Phase II for primary graft dysfunction in lung transplantation CXCR1 and CXCR2 x1 ⁄ 2pal-i1 SIRS Pepducin Preclinical CCL11 CAT-213 Asthma Blocking antibody Phase II CCR1 BX-471 MS, transplant rejection Nonpeptide antagonist Phase II for MS CCR3 GW-766994 asthma, allergy Nonpeptide antagonist Preclinical CCR5 UK-427857 AIDS Nonpeptide antagonist Preclinical CCR9 Traficet-EN IBD Small molecule drug Phase III CCR2 INCB3284 Rheumatoid arthritis, obese insulin-resistant diabetes Small molecule drug phase II CXCR4 CTCE-9908 Prostate cancer Small molecule drug Phase II LTB4 Montelukast Asthma, COPD Small molecule drug Approved for asthma Zafirlukast Pranlukast S1PR1, S1PR3, S1PR4, S1PR5 FTY720 Transplant rejection S1PR agonist Phase III for kidney transplantation Targeting leukocyte–endothelial cell interactions N. C. Kaneider et al. 4420 FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS combinations of ligands [20]. Their structural and func- tional diversity allows the integrins to play pivotal roles in many biological processes, including inflammation, he- mostasis and wound healing [21]. Dysregulation of inte- grins, however, contributes to the pathogenesis of many diseases. Therefore, therapeutic interve ntion of leukocyte recruitment by blocking integrins or their counter-recep- tors (ICAM, VCAMs a nd mucosal addressin cell adhe- sion molecule-1) is likely to exert anti-inflammatory effects in several diseases. Extensive efforts have been focused on the discovery and development of integrin antagonists for clinical applications. b2(CD11⁄ CD18) and a4 (CD49d) integrins are essential fo r the firm arrest of leukocytes to the endothelium [20]. Clinical trials wi th rovelizumab or erlizumab (mAbs directed aga inst CD18) (Table 2) failed to show any beneficial effects in ischemia- reperfusion injury after myocardial infarction or stroke [22,23]. Blockade of I CAM-1, the counter-receptor for CD18 on endothelial cells, with a mAb (enlimomab), showed negative effects in a phase II clinical trial in stroke patients [24]. These results dampened the enthusiasm for targeting integrin function i n ischemic settings. However, in inflammatory diseases, the inhibition of CD11a, which, together with CD18 forms the lymphocyte function-asso- ciated antigen-1 (LFA-1) complex, has been p roven to be beneficial. For example, odulimomab, which interferes with leukocyte migration by inhibiting CD11a, is used for the treatment of graft-versus-host disease and suppresses atopic dermatitis in animal models [6,25]. Efalizumab is a humanized IgG1 mAb that also targets the CD11a chain of LFA-1 and prevents LFA-1 from interacting with ICAM-1. E falizumab has b een successfully used in phase III clinical trials in patients with psoriasis [26]. Natal- izumab (tysabri), a mAb to the a4 integrin chain that blocks the binding of ve ry late an tigen-4 to VC AM-1, was tested in large clinical phase III trials against m ultiple sclerosis [27] and Crohn’s disease [28]. The outcome in these studies was very promising; however, the occurrence of progressive multifocal leukoencephalopathy in natal- izumab-treated patients has required further risk–benefit analysis of this promising therapy. In a clinical trial of ulcerative colitis, MLN02, an antibody against the a4b2 heterodimer, was tested in 181 patients and found to induce complete clinical and endoscopical remission in 33% (14% in the placebo group) [29]. However, the long- term beneficial effects of MLN02 in clinical practice are not known, suggesting the n eed for a dditional s tudies. GPCR GPCRs play a vital role in the signaling processes that control cell motility, growth, blood coagulation and inflammation. GPCRs are the largest known family of cell-surface receptors and are activated by chemokines, proteases, lipids and a wide variety of other molecules involved in inflammation. Multiple chemokines play critical roles in the initiation and perpetuation of inflammatory diseases. Activation of chemokine receptors by their ligands leads to the acti- vation of integrins, resulting in firm adhesion to the endothelium. Therefore, for many years, chemokine receptors and their ligands have been an attractive hunting ground for pharmaceutical companies (Table 2). There are several possible approaches to inhibit specific chemokines. These range from block- ing antibodies against chemokines or their receptors, small molecule receptor antagonists, or compounds that interdict components of downstream signal trans- duction pathways. In disease states such as systemic inflammatory response syndrome and, more specifically, severe sep- sis, an inability to down-regulate the inflammatory response leads to a hyperactivated state. To reduce neutrophil migration along chemotactic gradients, early efforts targeted receptor–ligand interactions with peptido-mimetics or utilized blocking antibodies. The first small molecule chemokine receptor antagonist was SB225002, which exhibited nanomolar inhibition against IL-8 binding to CXCR2, but not CXCR1 [30]. In chronic obstructive pulmonary disease, CXCR2 and IL-8 are up-regulated in the airways, and therefore blocking CXCR2 with SB225002 or other CXCR2 inhibitors may be particularly beneficial and studies are now entering the first clinical trials (Table 2). Fur- thermore, several preclinical studies with other CXCR1 and CXCR2 blocking agents have been shown to be efficacious in ischemia-reperfusion and sepsis models and are now being evaluated in the clinical situation [31–33]. The discovery that the chemokine receptors, CCR5 and CXCR4, are the coreceptors for CD4 in human immunodeficiency virus infection, provided a strong impetus for the rapid development of CCR5 and CXCR4 antagonists. In addition, the activation of CCR5 by regulated on activation, normal, T-cell expressed, and secreted (RANTES) has also been linked to the development of atherosclerosis, asthma, atopic dermatitis and other inflammatory diseases. CCR1 antagonists have been tested in multiple scler- osis and transplant rejection [34–36]. Small molecule CCR3 inhibitors have shown beneficial effects in aller- gen models of asthma [37]. Targeting CCR2 might be a potential strategy for preventing macrophage activa- tion in asthma, multiple sclerosis, rheumatoid arthritis and atherosclerosis [38], and this is being evaluated in clinical studies [38]. N. C. Kaneider et al. Targeting leukocyte–endothelial cell interactions FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS 4421 Sphingosine-1-phosphate (S1P) receptors were iden- tified in the context of defining the ligand for endothel- ial differentiation gene-1. Four S1P receptors (S1PR2, S1PR3, S1PR4 and S1PR5) were subsequently identi- fied and found to be expressed by many cell types. Recently, studies with a small molecule – 2-amino-2-[2- (4-octylphenyl) ethyl] propane-1,3-diol hydrochloride (FTY720) – identified during a screen for immunosup- pressant agents, have shown that FTY720 is an agonist for S1PR1, S1PR3, S1PR4 and S1PR5. FTY720 is a prodrug that requires activation by endogenous sphingosine-1-kinase. The active metabolite traps T cells in lymph nodes and initiates their homing into lymphoid organs [39]. FTY720 has been shown to be efficacious in the prevention of kidney transplant rejec- tion and might exert beneficial effects in other inflam- matory diseases [40,41]. Another family of GPCRs, namely the protease acti- vated receptors (PARs), has been shown to trigger inflammatory responses following tissue injury. PARs are tethered-ligand receptors that are activated by pro- teolytic cleavage of their extracellular domains [42]. Four different PARs have been identified: PAR1, PAR2, PAR3 and PAR4. Activation of endothelial and leukocyte PARs by proteases of the blood coagu- lation cascade has a profound impact on inflammation. Thus, PARs are considered to be promising therapeu- tic targets, and development of selective antagonists for the PARs might provide an alternative strategy for the treatment of inflammatory diseases [43,44]. Covic et al. discovered a novel class of compounds, termed pepducins, that inhibit receptor–G protein signaling [43]. These cell-penetrating lipopeptides are derived from the intracellular loops of PARs and other GPCRs. The hydrophobic lipid moiety is used to transport the peptide across the cell membrane and tethers the pepducin to the inner leaflet of the lipid bilayer in molecular proximity to the intracellular loops of the receptor. Pepducins were first designed to block PAR1 and PAR4 signaling in human platelets and required their cognate receptors for activity [43,44]. P1pal-7, a PAR1 antagonist pepducin, has been shown to inhibit tumor growth and angiogenesis in a breast cancer mouse model [45]. Second genera- tion pepducins derived from the first intracellular loop of GPCRs have proven to be highly selective against chemokine receptors and PARs [33,46]. Pepducins tar- geted against CXCR1 and CXCR2 chemokine recep- tors completely blocked IL-8 induced neutrophil migration without suppressing the response to bacterial fMLP. Moreover, even delayed treatment with CXCR1 ⁄ 2 pepducins conferred nearly 100% survival in a mouse model of sepsis in the absence of antibiot- ics [33]. These findings are of particular importance because the current treatment options for sepsis are primarily supportive. Future directions The challenge of the future will be to identify the key leukocyte subsets that initiate the pathologic processes of a certain disease and specifically inhibit leukocyte migration and activation without compromising the normal function of the immune system. The concept of immuno-modulation, rather than immuno-suppression, will probably be the optimal treatment for many inflammatory diseases such as the systemic inflam- matory response syndrome, atherosclerosis, asthma, chronic obstructive pulmonary disease, auto-immune disease and transplant rejection. References 1 Xie H, Lim YC, Luscinskas FW & Lichtman AH (1999) Acquisition of selectin binding and peripheral homing properties by CD4(+) and CD8(+) T cells. J Exp Med 189, 1765–1776. 2 Weninger W, Crowley MA, Manjunath N & von Andrian UH (2001) Migratory properties of naive, effector, and memory CD8(+) T cells. J Exp Med 194, 953–966. 3 Berland R & Wortis HH (2002) Origins and functions of B-1 cells with notes on the role of CD5. Annu Rev Immunol 20, 253–300. 4 Herzenberg LA (2000) B-1 cells: the lineage question revisited. Immunol Rev 175, 9–22. 5 MacConmara M & Lederer JA (2005) B cells. Crit Care Med 33, S514–S516. 6 Ulbrich H, Eriksson EE & Lindbom L (2003) Leuko- cyte and endothelial cell adhesion molecules as targets for therapeutic interventions in inflammatory disease. Trends Pharmacol Sci 24, 640–647. 7 Yanofsky SD, Baldwin DN, Butler JH, Holden FR, Jacobs JW, Balasubramanian P, Chinn JP, Cwirla SE, Peters-Bhatt E, Whitehorn EA et al. (1996) High affinity type I interleukin 1 receptor antagonists discov- ered by screening recombinant peptide libraries. Proc Natl Acad Sci USA 93, 7381–7386. 8 Macias I, Garcia-Perez S, Ruiz-Tudela M, Medina F, Chozas N & Giron-Gonzalez JA (2005) Modification of pro- and antiinflammatory cytokines and vascular- related molecules by tumor necrosis factor-a blockade in patients with rheumatoid arthritis. J Rheumatol 32, 2102–2108. 9 Pitzalis C, Pipitone N & Perretti M (2002) Regulation of leukocyte–endothelial interactions by glucocorticoids. Ann N Y Acad Sci 966, 108–118. Targeting leukocyte–endothelial cell interactions N. C. Kaneider et al. 4422 FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS 10 Sanchez-Madrid F & Gonzalez-Amaro R (2001) Drugs, inflammation and cell adhesion receptors. Expert Opin Pharmacother 2, 3–17. 11 Sukhova GK, Williams JK & Libby P (2002) Statins reduce inflammation in atheroma of nonhuman pri- mates independent of effects on serum cholesterol. Arterioscler Thromb Vasc Biol 22, 1452–1458. 12 McEver RP (2002) Selectins: lectins that initiate cell adhesion under flow. Curr Opin Cell Biol 14, 581–586. 13 Ley K (2001) Functions of selectins. Results Probl Cell Differ 33, 177–200. 14 Mocco J, Choudhri T, Huang J, Harfeldt E, Efros L, Klingbeil C, Vexler V, Hall W, Zhang Y, Mack W et al. (2002) HuEP5C7 as a humanized monoclonal anti-E ⁄ P- selectin neurovascular protective strategy in a blinded placebo-controlled trial of nonhuman primate stroke. Circ Res 91, 907–914. 15 Xia L, Sperandio M, Yago T, McDaniel JM, Cummings RD, Pearson-White S, Ley K & McEver RP (2002) P-selectin glycoprotein ligand-1-deficient mice have impaired leukocyte tethering to E-selectin under flow. J Clin Invest 109, 939–950. 16 Kaila N & Thomas BET (2002) Design and synthesis of sialyl Lewis (x) mimics as E- and P-selectin inhibitors. Med Res Rev 22, 566–601. 17 Friedrich M, Bock D, Philipp S, Ludwig N, Sabat R, Wolk K, Schroeter-Maas S, Aydt E, Kang S, Dam TN et al. (2006) Pan-selectin antagonism improves psoriasis manifestation in mice and man. Arch Dermatol Res 297, 345–351. 18 Beeh KM, Beier J, Meyer M, Buhl R, Zahlten R & Wolff G (2005) Bimosiamose, an inhaled small-molecule pan-selectin antagonist, attenuates late asthmatic reactions following allergen challenge in mild asth- matics: A randomized, double-blind, placebo- controlled clinical cross-over-trial. Pulm Pharmacol Ther 19, 233–241. 19 Wienrich BG, Krahn T, Schon M, Rodriguez ML, Kramer B, Busemann M, Boehncke WH & Schon MP (2006) Structure–function relation of efomycines, a fam- ily of small-molecule inhibitors of selectin functions. J Invest Dermatol 126, 882–889. 20 Shimaoka M & Springer TA (2003) Therapeutic antago- nists and conformational regulation of integrin function. Nat Rev Drug Discov 2 , 703–716. 21 Hynes RO (1992) Integrins: versatility, modulation, and signaling in cell adhesion. Cell 69, 11–25. 22 Faxon DP, Gibbons RJ, Chronos NA, Gurbel PA & Sheehan F (2002) The effect of blockade of the CD11 ⁄ CD18 integrin receptor on infarct size in patients with acute myocardial infarction treated with direct angioplasty: the results of the HALT-MI study. JAm Coll Cardiol 40, 1199–1204. 23 Baran KW, Nguyen M, McKendall GR, Lambrew CT, Dykstra G, Palmeri ST, Gibbons RJ, Borzak S, Sobel BE, Gourlay SG et al. (2001) Double-blind, randomized trial of an anti-CD18 antibody in conjunction with recombinant tissue plasminogen activator for acute myocardial infarction: limitation of myocardial infarction following thrombolysis in acute myocardial infarction (LIMIT AMI) study. Circulation 104, 2778–2783. 24 Sherman D, the Enlimomab Acute Stroke Trial Investi- gators (2001) Use of anti-ICAM-1 therapy in ischemic stroke: results of the Enlimomab Acute Stroke Trial. Neurology 57, 1428–1434. 25 Ohmura T, Konomi A, Satoh Y, Hayashi T, Tsunenari I, Kadota T, Panzenbeck MJ & Satoh H (2004) Sup- pression of atopic-like dermatitis by treatment with anti- body to lymphocyte function-associated antigen-1 in NC ⁄ Nga mouse. Eur J Pharmacol 504, 113–117. 26 Joshi A, Bauer R, Kuebler P, White M, Leddy C, Compton P, Garovoy M, Kwon P, Walicke P & Dedrick R (2006) An overview of the pharmacokinetics and pharmacodynamics of efalizumab: a monoclonal antibody approved for use in psoriasis. J Clin Pharma- col 46, 10–20. 27 Miller DH, Khan OA, Sheremata WA, Blumhardt LD, Rice GP, Libonati MA, Willmer-Hulme AJ, Dalton CM, Miszkiel KA & O’Connor PW (2003) A controlled trial of natalizumab for relapsing multiple sclerosis. N Engl J Med 348, 15–23. 28 Ghosh S, Goldin E, Gordon FH, Malchow HA, Rask- Madsen J, Rutgeerts P, Vyhnalek P, Zadorova Z, Pal- mer T & Donoghue S (2003) Natalizumab for active Crohn’s disease. N Engl J Med 348, 24–32. 29 Feagan BG, Greenberg GR, Wild G, Fedorak RN, Pare P, McDonald JW, Dube R, Cohen A, Steinhart AH, Landau S et al. (2005) Treatment of ulcerative colitis with a humanized antibody to the alpha4beta7 integrin. N Engl J Med 352, 2499–2507. 30 White JR, Lee JM, Young PR, Hertzberg RP, Jurewicz AJ, Chaikin MA, Widdowson K, Foley JJ, Martin LD, Griswold DE et al. (1998) Identification of a potent, selective non-peptide CXCR2 antagonist that inhibits interleukin-8-induced neutrophil migration. J Biol Chem 273, 10095–10098. 31 Sekido N, Mukaida N, Harada A, Nakanishi I, Watanabe Y & Matsushima K (1993) Prevention of lung reperfusion injury in rabbits by a monoclonal anti- body against interleukin-8. Nature 365, 654–657. 32 Bertini R, Allegretti M, Bizzarri C, Moriconi A, Locati M, Zampella G, Cervellera MN, Di Cioccio V, Cesta MC, Galliera E et al. (2004) Noncompetitive allosteric inhibitors of the inflammatory chemokine receptors CXCR1 and CXCR2: prevention of reperfusion injury. Proc Natl Acad Sci USA 101, 11791–11796. 33 Kaneider NC, Agarwal A, Leger AJ & Kuliopulos A (2005) Reversing systemic inflammatory response syn- drome with chemokine receptor pepducins. Nat Med 11, 661–665. N. C. Kaneider et al. Targeting leukocyte–endothelial cell interactions FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS 4423 34 Trebst C, Sorensen TL, Kivisakk P, Cathcart MK, Hes- selgesser J, Horuk R, Sellebjerg F, Lassmann H & Ran- sohoff RM (2001) CCR1+ ⁄ CCR5+ mononuclear phagocytes accumulate in the central nervous system of patients with multiple sclerosis. Am J Pathol 159, 1701–1710. 35 Horuk R, Shurey S, Ng HP, May K, Bauman JG, Islam I, Ghannam A, Buckman B, Wei GP, Xu W et al. (2001) CCR1-specific non-peptide antagonist: efficacy in a rab- bit allograft rejection model. Immunol Lett 76, 193–201. 36 Horuk R, Clayberger C, Krensky AM, Wang Z, Grone HJ, Weber C, Weber KS, Nelson PJ, May K, Rosser M et al. (2001) A non-peptide functional antagonist of the CCR1 chemokine receptor is effective in rat heart trans- plant rejection. J Biol Chem 276, 4199–4204. 37 White JR, Lee JM, Dede K, Imburgia CS, Jurewicz AJ, Chan G, Fornwald JA, Dhanak D, Christmann LT, Darcy MG et al. (2000) Identification of potent, select- ive non-peptide CC chemokine receptor-3 antagonist that inhibits eotaxin-, eotaxin-2-, and monocyte chemo- tactic protein-4-induced eosinophil migration. J Biol Chem 275, 36626–36631. 38 Luster AD, Alon R & von Andrian UH (2005) Immune cell migration in inflammation: present and future thera- peutic targets. Nat Immunol 6, 1182–1190. 39 Brinkmann V, Davis MD, Heise CE, Albert R, Cottens S, Hof R, Bruns C, Prieschl E, Baumruker T, Hiestand P et al. (2002) The immune modulator FTY720 targets sphingosine 1-phosphate receptors. J Biol Chem 277, 21453–21457. 40 Muller H, Hofer S, Kaneider N, Neuwirt H, Mosheimer B, Mayer G, Konwalinka G, Heufler C & Tiefenthaler M (2005) The immunomodulator FTY720 interferes with effector functions of human monocyte-derived den- dritic cells. Eur J Immunol 35, 533–545. 41 Kaneider NC, Lindner J, Feistritzer C, Sturn DH, Mos- heimer BA, Djanani AM & Wiedermann CJ (2004) The immune modulator FTY720 targets sphingosine-kinase- dependent migration of human monocytes in response to amyloid beta-protein and its precursor. Faseb J 18, 1309–1311. 42 Seeley S, Covic L, Jacques SL, Sudmeier J, Baleja JD & Kuliopulos A (2003) Structural basis for thrombin acti- vation of a protease-activated receptor: inhibition of intramolecular liganding. Chem Biol 10, 1033–1041. 43 Covic L, Gresser AL, Talavera J, Swift S & Kuliopulos A (2002) Activation and inhibition of G protein-coupled receptors by cell-penetrating membrane-tethered pep- tides. Proc Natl Acad Sci USA 99, 643–648. 44 Covic L, Misra M, Badar J, Singh C & Kuliopulos A (2002) Pepducin-based intervention of thrombin-recep- tor signaling and systemic platelet activation. Nat Med 8, 1161–1165. 45 Boire ACL, Agarwal A, Jaques S, Sherifi S & Kuliopu- los A (2005) PAR1 is a Matrix metalloprotease-1 recep- tor that promotes invasion and tumorigenesis of breast cancer cells. Cell 120, 303–313. 46 Leger AJ, Jaques SL, Badar J, Kaneider NC, Derian CK, Andrade-Gordon P, Covic L & Kuliopulos A (2006) Blocking the protease-activated receptor 1–4 het- eroddimer in platelet-mediated thrombosis. Circulation 113, 1244–1254. 4424 FEBS Journal 273 (2006) 4416–4424 ª 2006 The Authors Journal compilation ª 2006 FEBS Targeting leukocyte–endothelial cell interactions N. C. Kaneider et al. . MINIREVIEW Therapeutic targeting of molecules involved in leukocyte–endothelial cell interactions Nicole C. Kaneider 1 ,. by inhibition of chemokine G protein- coupled receptor (GPCR) signaling [6]. Several anti- in ammatory drugs indirectly inhibit components involved in leukocyte–endothelial