Inducing neutrophil recruitment in the liver of ICAM-1-deficient mice using polyethyleneimine grafted with Pluronic P123 as an organ-specific carrier for transgenic ICAM-1

Gene regulation of intracellular adhesion molecule-1 (ICAM-1): A molecule with multiple functions

Intracellular adhesion molecule 1 (ICAM-1) is one of the most extensively studied inducible cell adhesion molecules which is responsible for several immune functions like T cell activation, extravasation, inflammation, etc. The molecule is constitutively expressed over the cell surface and is regulated up / down in response to inflammatory mediators like cellular stress, proinflammatory cytokines, viral infection. These stimuli modulate the expression of ICAM-1 primarily through regulating the ICAM-1 gene transcription. On account of the presence of various binding sites for NF-κB, AP-1, SP-1, and many other transcription factors, the architecture of the ICAM-1 promoter become complex. Transcription factors in union with other transcription factors, coactivators, and suppressors promote their assembly in a stereospecific manner on ICAM-1 promoter which mediates ICAM-1 regulation in response to different stimuli. Along with transcriptional regulation, epigenetic modifications also play a pivotal role in controlling ICAM-1 expression on different cell types. In this review, we summarize the regulation of ICAM-1 expression both at the transcriptional as well as post-transcriptional level with an emphasis on transcription factors and signaling pathways involved.

Non-viral transfection vectors: are hybrid materials the way forward?

Transfection is a process by which oligonucleotides (DNA or RNA) are delivered into living cells. This allows the synthesis of target proteins as well as their inhibition (gene silencing). However, oligonucleotides cannot cross the plasma membrane by themselves; therefore, efficient carriers are needed for successful gene delivery. Recombinant viruses are among the earliest described vectors. Unfortunately, they have severe drawbacks such as toxicity and immunogenicity. In this regard, the development of non-viral transfection vectors has attracted increasing interests, and has become an important field of research. In the first part of this review we start with a tutorial introduction into the biological backgrounds of gene transfection followed by the classical non-viral vectors (cationic organic carriers and inorganic nanoparticles). In the second part we highlight selected recent reports, which demonstrate that hybrid vectors that combine key features of classical carriers are a remarkable strategy to address the current challenges in gene delivery.

Deletion of caveolin-1 attenuates LPS/GalN-induced acute liver injury in mice

Acute hepatic injury caused by inflammatory liver disease is associated with high mortality. This study examined the role of caveolin-1 (Cav-1) in lipopolysaccharide (LPS) and D-galactosamine (GalN)-induced fulminant hepatic injury in wild type and Cav-1-null (Cav-1-/- ) mice. Hepatic Cav-1 expression was induced post-LPS/GalN treatment in wild-type mice. LPS/GalN-treated Cav-1-/- mice showed reduced lethality and markedly attenuated liver damage, neutrophil infiltration and hepatocyte apoptosis as compared to wild-type mice. Cav-1 deletion significantly reduced LPS/GalN-induced caspase-3, caspase-8 and caspase-9 activation and pro-inflammatory cytokine and chemokine expression. Additionally, Cav-1-/- mice showed suppressed expression of Toll-like receptor 4 (TLR4) and CD14 in Kupffer cells and reduced expression of vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 in liver cells. Cav-1 deletion impeded LPS/GalN-induced inducible nitric oxide synthase expression and nitric oxide production and hindered nuclear factor-κB (NF-κB) activation. Taken together, Cav-1 regulated the expression of mediators that govern LPS-induced inflammatory signalling in mouse liver. Thus, deletion of Cav-1 suppressed the inflammatory response mediated by the LPS-CD14-TLR4-NF-κb pathway and alleviated acute liver injury in mice.

ICAM-1: isoforms and phenotypes

ICAM-1 plays an important role in leukocyte trafficking, immunological synapse formation, and numerous cellular immune responses. Although considered a single glycoprotein, there are multiple membrane-bound and soluble ICAM-1 isoforms that arise from alternative splicing and proteolytic cleavage during inflammatory responses. The function and expression of these isoforms on various cell types are poorly understood. In the generation of ICAM-1-deficient mice, two isoform-deficient ICAM-1 mutants were inadvertently produced as a result of alternative splicing. These mice, along with true ICAM-1-deficient mice and newly generated ICAM-1-transgenic mice, have provided the opportunity to begin examining the role of ICAM-1 isoforms (singly or in combination) in various disease settings. In this review, we highlight the sharply contrasting disease phenotypes using ICAM-1 isoform mutant mice. These studies demonstrate that ICAM-1 immunobiology is highly complex but that individual isoforms, aside from the full-length molecule, make significant contributions to disease development and pathogenesis.

Expression of a single ICAM-1 isoform on T cells is sufficient for development of experimental autoimmune encephalomyelitis

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in leukocyte trafficking, induction of cellular immune responses, and immunological synapse formation. As a member of the immunoglobulin superfamily of adhesion proteins, ICAM-1 is composed of repeating Ig-like domains, a transmembrane domain, and short cytoplasmic tail that participates in intracellular signaling events. At least seven ICAM-1 protein isoforms are generated by alternative splicing, however little is known regarding their immunobiology. We have previously shown using different lines of ICAM-1 mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay) ) that expression of alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. In this study, we show using a newly developed transgenic mouse (CD2-Icam1(D4del) /Icam1(null) ) that T-cell-specific expression of a single ICAM-1 isoform composed of Ig domains 1, 2, 3, and 5 can mediate the initiation and progression of EAE. Our results indicate that the ICAM-1 isoform lacking Ig domain 4 can drive pathogenesis in demyelinating disease and may be a novel therapeutic target for treating multiple sclerosis.

Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability

We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic metal chelates as crosslinkers. These crosslinkers are used to formulate polyacrylamide-based nanogels (diameter 50 to 85 nm) yielding contrast agents with enhanced relaxivities (up to 6-fold greater than Dotarem®), because this nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd3+ within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd3+. This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy.

From rationally designed polymeric and peptidic systems to sophisticated gene delivery nano-vectors

Lack of safe, efficient and controllable methods for delivering therapeutic genes appears to be the most important factor preventing human gene therapy. Safety issues encountered with viral vectors have prompted substantial attention to in vivo investigations with non-viral vectors throughout the past decade. However, developing non-viral vectors with effectiveness comparable to viral ones has been a challenge. The strategy of designing multifunctional synthetic carriers targeting several extracellular and intracellular barriers in the gene transfer pathway has emerged as a promising approach to improving the efficacy of gene delivery systems. This review will explain how sophisticated synthetic vectors can be created by combining conventional polycationic vectors such as polyethylenimine and basic amino acid peptides with additional polymers and peptides that are designed to overcome potential barriers to the gene delivery process.

Arginine-rich hydrophobic polyethylenimine: potent agent with simple components for nucleic acid delivery

Conjugation of various arginine-rich peptide sequences to vectors based on 10 kDa polyethylenimine (PEI) and its hydrophobic derivative (hexanoate-PEI) was investigated as a strategy for improving pDNA and siRNA transfection activities. Six different arginine-histidine (RH) sequences and two arginine-serine (RS) sequences with a range of R/H ratios were designed and coupled to PEI and hexanoate-PEI. All arginine-rich peptide derivatives of PEI significantly enhanced luciferase gene expression compared to PEI 10 kDa alone. Hexanoate-PEI derivatives exhibited higher transfection activity than underivatized PEI vectors. Improved transfection activity may have resulted at least in part from use of higher vector/DNA ratios made possible by reduced cytotoxicity of vectors, and to use of vectors with higher molecular weights. Vectors that were the most efficient in pDNA delivery and transfection were also the most effective in siRNA delivery and protein expression knock down.

Experimental cerebral malaria develops independently of endothelial expression of intercellular adhesion molecule-1 (icam-1)

Cerebral malaria (CM) is a severe clinical complication of Plasmodium falciparum malaria infection and is characterized by a high fatality rate and neurological damage. Sequestration of parasite-infected red blood cells in brain microvasculature utilizes host- and parasite-derived adhesion molecules and is an important factor in the development of CM. ICAM-1, an alternatively spliced adhesion molecule, is believed to be critical on endothelial cells for infected red blood cell sequestration in CM. Using ICAM-1 mutant mice, we found that the full-length ICAM-1 isoform is not required for development of murine experimental CM (ECM) and that ECM phenotype varies with the combination of ICAM-1 isoforms expressed. Furthermore, we observed development of ECM in transgenic mice expressing ICAM-1 only on leukocytes, indicating that endothelial cell expression of this adhesion molecule is not required for disease pathogenesis. We propose that ICAM-1-dependent cellular aggregation, independent of ICAM-1 expression on the cerebral microvasculature, contributes to ECM.

Meningitic Escherichia coli K1 penetration and neutrophil transmigration across the blood-brain barrier are modulated by alpha7 nicotinic receptor

Alpha7 nicotinic acetylcholine receptor (nAChR), an essential regulator of inflammation, is abundantly expressed in hippocampal neurons, which are vulnerable to bacterial meningitis. However, it is unknown whether α7 nAChR contributes to the regulation of these events. In this report, an aggravating role of α7 nAChR in host defense against meningitic E. coli infection was demonstrated by using α7-deficient (α7(-/-)) mouse brain microvascular endothelial cells (BMEC) and animal model systems. As shown in our in vitro and in vivo studies, E. coli K1 invasion and polymorphonuclear neutrophil (PMN) transmigration across the blood-brain barrier (BBB) were significantly reduced in α7(-/-) BMEC and α7(-/-) mice. Stimulation by nicotine was abolished in the α7(-/-) cells and animals. The same blocking effect was achieved by methyllycaconitine (α7 antagonist). The tight junction molecules occludin and ZO-1 were significantly reduced in the brain cortex of wildtype mice infected with E. coli and treated with nicotine, compared to α7(-/-) cells and animals. Decreased neuronal injury in the hippocampal dentate gyrus was observed in α7(-/-) mice with meningitis. Proinflammatory cytokines (IL-1β, IL-6, TNFα, MCP-1, MIP-1alpha, and RANTES) and adhesion molecules (CD44 and ICAM-1) were significantly reduced in the cerebrospinal fluids of the α7(-/-) mice with E. coli meningitis. Furthermore, α7 nAChR is the major calcium channel for nicotine- and E. coli K1-increased intracellular calcium concentrations of mouse BMEC. Taken together, our data suggest that α7 nAChR plays a detrimental role in the host defense against meningitic infection by modulation of pathogen invasion, PMN recruitment, calcium signaling and neuronal inflammation.

Self-assembled micellar aggregates based monomethoxyl poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(aminoethyl methacrylate) triblock copolymers as efficient gene delivery vectors

Amphiphilic triblock copolymers monomethoxyl poly(ethylene glycol) (mPEG)-b-poly(ε-caprolactone) (PCL)-b-poly(aminoethyl methacrylate)s (PAMAs) (mPECAs) were synthesized as gene delivery vectors. They exhibited lower cytotoxicity and higher transfection efficiency in COS-7 cells in presence of serum compared to 25 kDa bPEI. The influence of mPEG and PCL segments in mPECAs was evaluated by comparing with corresponding diblock copolymers. The studies showed the incorporation of the hydrophobic PCL segment in triblock copolymers affected the binding capability to pDNA and surface charges of complexes due to the formation of micelles increasing the local charges. The presence of mPEG segment in gene vector decreased the surface charges of the complexes and increased the stability of the complexes in serum because of the steric hindrance effect. It was also found that the combination of PEG and PCL segments into one macromolecule might lead to synergistic effect for better transfection efficiency in serum.

Differential ICAM-1 isoform expression regulates the development and progression of experimental autoimmune encephalomyelitis

Intercellular adhesion molecule-1 (ICAM-1) functions in leukocyte trafficking, activation, and the formation of the immunological synapse. ICAM-1 is a member of the immunoglobulin superfamily of adhesion proteins, which share a similar structure of repeating Ig-like domains. Many genes in this family, including ICAM-1, show alternative splicing leading to the production of different protein isoforms, although little functional information is available regarding the expression patterns, ligand interactions, and functions of these isoforms, especially those arising from the ICAM-1 gene. In this study, we show using different lines of mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay)) that alterations in the expression of the alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. Icam1(tm1Jcgr) mutant mice, unlike Icam1(tm1Bay) mutants, do not express isoforms containing the Mac-1 binding domain and had significantly attenuated of EAE. In contrast, Icam1(tm1Bay) mice developed severe EAE in both active and adoptive transfer models compared to both Icam1(tm1Jcgr) and wild type mice. We also observed that T cells from Icam1(tm1Bay) mice displayed increased proliferation kinetics and produced higher levels of IFN-gamma compared to Icam1(tm1Jcgr) and wild type mice. Thus, our investigations show that the alternatively spliced ICAM-1 isoforms are functional, and play key roles during the progression of CNS inflammation and demyelination in EAE. Furthermore, our findings suggest that these isoforms may also play key roles in controlling the development of inflammatory diseases such as multiple sclerosis, possibly through differential engagement with ICAM-1 ligands such as Mac-1.

Drug discovery using the regulation of gene expression

The expression of a disease-relevant protein is controlled by a transcriptional program specifically regulated at all stages of normal development and during the adult life. Thus, regulation of gene expression as an approach to drug discovery is conceptually appealing because it provides a rational basis for molecular strategies aimed at modulating gene expression in given cell types and/or at a given time. Indeed, numerous pharmacologic agents have been identified that can either restore or suppress disease-relevant protein expression. In this review, the author critically examines new strategies and methodologies that are being used and developed to identify and validate new therapeutic targets by taking advantage of our knowledge on mechanisms regulating their expression at the transcriptional and post-transcriptional levels. The author also examines the impact of genome-wide approaches and methods aimed at controlling epigenetic mechanisms of gene regulation and concludes by extrapolating on future trends.

Recent advances in rational gene transfer vector design based on poly(ethylene imine) and its derivatives

The continually increasing wealth of knowledge about the role of genes involved in acquired or hereditary diseases renders the delivery of regulatory genes or nucleic acids into affected cells a potentially promising strategy. Apart from viral vectors, non-viral gene delivery systems have recently received increasing interest, due to safety concerns associated with insertional mutagenesis of retro-viral vectors. Especially cationic polymers may be particularly attractive for the delivery of nucleic acids, since they allow a vast synthetic modification of their structure enabling the investigation of structure-function relationships. Successful clinical application of synthetic polycations for gene delivery will depend primarily on three factors, namely (1) an enhancement of the transfection efficiency, (2) a reduction in toxicity and (3) an ability of the vectors to overcome numerous biological barriers after systemic or local administration. Among the polycations presently used for gene delivery, poly(ethylene imine), PEI, takes a prominent position, due to its potential for endosomal escape. PEI as well as derivatives of PEI currently under investigation for DNA and RNA delivery will be discussed. This review focuses on structure-function relationships and the physicochemical aspects of polyplexes which influence basic characteristics, such as complex formation, stability or in vitro cytotoxicity, to provide a basis for their application under in vivo conditions. Rational design of optimized polycations is an objective for further research and may provide the basis for a successful cationic polymer-based gene delivery system in the future.

Intercellular adhesion molecule-1 expression is required on multiple cell types for the development of experimental autoimmune encephalomyelitis

Many members of the Ig superfamily of adhesion molecules, such as ICAM-1 and VCAM-1, have been implicated in the pathogenesis of multiple sclerosis. Although it is well-established that VCAM-1/VLA-4 interactions can play important roles in mediating CNS inflammatory events in multiple sclerosis patients and during the development of experimental allergic encephalomyelitis (EAE), the contributions of ICAM-1 are poorly understood. This is due in large part to conflicting results from Ab inhibition studies and the observation of exacerbated EAE in ICAM-1 mutant mice that express a restricted set of ICAM-1 isoforms. To determine ICAM-1-mediated mechanisms in EAE, we analyzed ICAM-1 null mutant mice (ICAM-1(null)), which express no ICAM-1 isoforms. ICAM-1(null) mice had significantly attenuated EAE characterized by markedly reduced spinal cord T cell infiltration and IFN-gamma production by these cells. Adoptive transfer of Ag-restimulated T cells from wild-type to ICAM-1(null) mice or transfer of ICAM-1(null) Ag-restimulated T cells to control mice failed to induce EAE. ICAM-1(null) T cells also showed reduced proliferative capacity and substantially reduced levels of IFN-gamma, TNF-alpha, IL-4, IL-10, and IL-12 compared with that of control T cells following myelin oligodendrocyte glycoprotein 35-55 restimulation in vitro. Our results indicate that ICAM-1 expression is critical on T cells and other cell types for the development of demyelinating disease and suggest that expression of VCAM-1 and other adhesion molecules cannot fully compensate for the loss of ICAM-1 during EAE development.

Polyethylenimine-based non-viral gene delivery systems

Gene therapy has become a promising strategy for the treatment of many inheritable or acquired diseases that are currently considered incurable. Non-viral vectors have attracted great interest, as they are simple to prepare, rather stable, easy to modify and relatively safe, compared to viral vectors. Unfortunately, they also suffer from a lower transfection efficiency, requiring additional effort for their optimization. The cationic polymer polyethylenimine (PEI) has been widely used for non-viral transfection in vitro and in vivo and has an advantage over other polycations in that it combines strong DNA compaction capacity with an intrinsic endosomolytic activity. Here, we give some insight into strategies developed for PEI-based non-viral vectors to overcome intracellular obstacles, including the improvement of methods for polyplex preparation and the incorporation of endosomolytic agents or nuclear localization signals. In recent years, PEI-based non-viral vectors have been locally or systemically delivered, mostly to target gene delivery to tumor tissue, the lung or liver. This requires strategies to efficiently shield transfection polyplexes against non-specific interaction with blood components, extracellular matrix and untargeted cells and the attachment of targeting moieties, which allow for the directed gene delivery to the desired cell or tissue. In this context, materials, facilitating the design of novel PEI-based non-viral vectors are described.

Biophysical characterization of complexation of DNA with block copolymers of poly(2-dimethylaminoethyl) methacrylate, poly(ethylene oxide), and poly(propylene oxide)

The interactions of DNA (salmon testes) with two new cationic block copolymers made of poly(2-dimethylaminoethyl) methacrylate and poly(ethylene oxide), PEO-pDMAEMA, or poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), L92-pDMAEMA, were studied with the aim to understand their different in vitro transfection efficiencies when used as nonviral delivery vectors. PEO-pDMAEMA does not show surface activity while L92-pDMAEMA is as surface active as its parent Pluronic L92. Surface tension, titration microcalorimetry, ethidium bromide displacement, and zeta-potential measurements were carried out in phosphate buffers at pH 5 and 7. The association of L92-pDMAEMA with DNA was strongly exothermic at both pHs; the critical aggregation concentration (CAC) corresponded to a N/P ratio of 0.3, the maximum energy evolved was reached for N/P ratios of 0.82 and 1.27 at pH 5 and pH 7, respectively, and the saturation occurred for N/P ratios close to 2. The presence of L92 in the structure of this new block copolymer apparently did not modify the thermodynamic parameters of the interaction with DNA. In contrast, the interaction with PEO-pDMAEMA was significantly less exothermic, and CAC and saturation occurred for N/Ps equal to 0.43 and 1.37, respectively. The strong affinity of L92-pDMAEMA for DNA was reflected in its capacity to displace ethidium bromide and in the jump in the values of the zeta potential when N/P is near 1. Above the N/P ratio at which electroneutral polyplexes are formed, only at pH 5 an excess of L92-pDMAEMA is incorporated in the complexes, resulting in positively charged complexes. The profile of the zeta-potential values obtained for mixtures of L92-pDMAEMA with Pluronic P123 showed a shift to a lower N/P ratio, owing to an easier interaction of L92-pDMAEMA molecules with DNA in the presence of P123. Additionally, a visual inspection of the systems indicates that P123 contributes to stabilize/solubilize the DNA/cationic polymer aggregates, by avoiding the typical phase separation near the charge neutralization point. The information obtained can be particularly useful to optimize the conditions to form efficient polyplexes for gene delivery systems.

Mixed polymer micelles of amphiphilic and cationic copolymers for delivery of antisense oligonucleotides

Cationic copolymers were synthesized by conjugation of branched 2 kDa polyethylenimine (PEI) and Pluronic block copolymers (F38, P85, P123). Compositions of these copolymers mixed with corresponding free Pluronics at weight ratio 1:9 were used to complex phosphorothioate oligonucleotides (ODN). As a result stable suspensions of small micelle-like particles (<220 nm) were obtained. Incorporation of ODN in these formulations increased uptake of ODN in KBv cells and increased sequence specific activity of antisense ODN targeted against MDR gene in multidrug resistant cells resulting in inhibition of the functional activity of P-glycoprotein (P-gp) in these cells. Furthermore, these formulations increased transport of ODN across model intestinal barrier, Caco-2 cell monolayers, suggesting that they could be useful for oral delivery of biologically active ODN.

Polycationic Block Copolymers of Poly(ethylene oxide) and Poly(propylene oxide) for Cell Transfection

A facile, one-step synthesis of cationic block copolymers of poly(2-N-(dimethylaminoethyl) methacrylate) (pDMAEMA) and copolymers of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) has been developed. The PEO-PPO-PEO-pDMAEMA (L92-pDMAEMA) and PEO-pDMAEMA copolymers were obtained via free radical polymerization of DMAEMA initiated by polyether radicals generated by cerium(IV). Over 95% of the copolymer fraction was of molecular mass ranging from 6.9 to 7.1 kDa in size, indicating the prevalence of the polyether-monoradical initiation mechanism. The L92-pDMAEMA copolymers possess parent surfactant-like surface activity. In contrast, the PEO-pDMAEMA copolymers lack significant surface activity. Both copolymers can complex with DNA. Hydrodynamic radii of the complexes of the L92-pDMAEMA and PEO-pDMAEMA with plasmid DNA ranged in size from 60 to 400 nm, depending on the copolymer/DNA ratio. Addition of Pluronic P123 to the L92-pDMAEMA complexes with DNA masked charges and decreased the tendency of the complex to aggregate, even at stoichiometric polycation/DNA ratios. The transfection efficiency of the L92-pDMAEMA copolymer was by far greater than that of the PEO-pDMAEMA copolymer. An extra added Pluronic P123 further increased the transfecton efficacy of L92-pDMAEMA, but did not affect that of PEO-pDMAEMA.

Pluronic Block Copolymers for Gene Delivery

Amphiphilic block copolymers of poly(ethylene oxide) and poly(propylene oxide) called Pluronic or poloxamer are commercially available pharmaceutical excipients. They recently attracted considerable attention in gene delivery applications. First, they were shown to increase the transfection with adenovirus and lentivirus vectors. Second, they were shown to increase expression of genes delivered into cells using non-viral vectors. Third, the conjugates of Pluronic with polycations, were used as DNA-condensing agents to form polyplexes. Finally, it was demonstrated that they can increase regional expression of the naked DNA after its injection in the skeletal and cardiac muscles or tumor. Therefore, there is substantial evidence that Pluronic block copolymers can improve gene expression with different delivery routes and different types of vectors, including naked DNA. These results and possible mechanisms of Pluronic effects are discussed. At least in some cases, Pluronic can act as biological adjuvants by activating selected signaling pathways, such as NF-kappaB, and upregulating the transcription of the genes.

Identification of a murine ICAM-1-specific peptide by subtractive phage library selection on cells

The ICAM-1 adhesion molecule is expressed selectively at low levels on endothelial cells but is strongly upregulated in dysfunctional endothelial cells associated with inflammation, cancer, and atherogenesis. Using COS-7 cells transfected with murine ICAM-1 (mICAM-1) as a target receptor, a phage display library was screened. Clones were selected by elution with a mAb specific for a functional epitope of ICAM-1 and a novel peptide sequence binding to the extracellular domain of mICAM-1 was identified that can potentially be used as a targeting vector aimed at dysfunctional endothelium. We further showed that the targeting specificity of the peptide was retained following its incorporation at the N terminal end of a large chimeric protein. Moreover, this chimeric protein containing the mICAM-1-specific sequence was found to inhibit ICAM-1-mediated intercellular adhesion during antigen presentation. Taken together, these results demonstrate the potential for improving the cell-selectivity and properties of therapeutical agents toward targeting adhesion molecules involved in cell-cell interactions.