Galectins: novel anti-inflammatory drug targets

Galectins are a protein family defined by their affinity for beta-galactosides and consensus sequences. They are pleiotropic regulators involved in a multitude of functions, both in and out of the cell. Extracellularly, they have the potential to bind to various surface receptors on a variety of cell types as well as extracellular matrix (ECM) proteins, thus causing cell activation or apoptosis, modulating cell adhesion and inducing cell migration. Intracellularly, they can regulate cell growth, apoptosis and cell cycle progression. Galectins are either pro-inflammatory or anti-inflammatory. Some, such as galectin-1, may be employed as anti-inflammatory agents, while others, such as galectin-3, are evidently suitable targets for anti-inflammatory drugs. The extracellular functions of galectins involve their lectin-carbohydrate interactions and thus their carbohydrate ligands or mimetics would be suitable inhibitors. While the intracellular functions of galectins do not appear to engage lectin-carbohydrate interactions, the carbohydrate-binding sites of these proteins may still be involved. Therefore, the same inhibitors may be used regardless of whether intracellular or extracellular galectins are to be targeted.     

Acute actions and novel targets of matrix metalloproteinases in the heart and vasculature

Matrix metalloproteinases (MMPs) have been shown to play significant roles in a number of physiological as well as pathological processes. Best known to proteolyse components of the extracellular matrix, MMPs have recently been discovered to also target a growing list of proteins apart from these, both inside and outside the cell. MMPs have also been traditionally thought of as enzymes involved in chronic processes such as angiogenesis, remodelling and atherosclerosis on a days-week time-scale. However they are now understood to also act acutely in response to oxidative stress on a minutes time-scale on non-extracellular matrix substrates. This review focuses on the acute actions and both extracellular and intracellular targets of two prominent MMP family members, MMP-2 and -9, in cardiovascular diseases including ischaemia/reperfusion injury, inflammatory heart disease, septic shock and pre-eclampsia. Also discussed are various ways of regulating MMP activity, including post-translational mechanisms, the endogenous tissue inhibitors of metalloproteinases and pharmacological inhibitors. A comprehensive understanding of MMP biology is necessary for the development of novel pharmacological therapies to combat the impact of cardiovascular disease.     

Adolescent drug taking: role of family and peers

To study the influence of family and peers on drug-taking behavior in adolescents, confidential self-reports were obtained from 3333 London adolescents about their use of solvents and illicit drugs. They were also asked about their perception of their best friend's and any family member's use of drugs. The results show that both family and peer's use of drugs were influential. However, peers were more influential than family regardless of whether they took drugs or not and both factors can also have a synergistic effect. The implications of the findings are discussed.     

Cholesterol, cardiolipin, and mitochondria permeabilisation

Apoptosis is a form of programmed cell death required for the development and for the proper functioning of multicellular organisms. It is defined by a combination of morphological and biochemical modifications that result from the activation of a family of proteases called caspases. Several pathways can lead to caspase activation and they often involve the release of apoptogenic factors normally sequestered in the mitochondrial intermembrane space. Complete release of mitochondrial pro-apoptotic factors ultimately results in cell death, whether in a caspase-dependent or independent manner. A tight control of mitochondrial permeability is therefore essential. Mutations of regulators of the process, such as proteins of the Bcl-2 family, have indeed been reported in many cancers. In addition, the contributions of lipids, both as regulators of protein activities and as components of the pore itself, are starting to be unravelled. Early on, the role of the mitochondria-specific phospholipid cardiolipin as a targeting signal for pro-apoptotic proteins of the Bcl-2 family was discovered. This role was then expanded since it was shown that cardiolipin also supports conformational changes undergone by proteins of the Bcl-2 family, serves as a docking station for additional pro-apoptotic factors, and is essential for the permeabilisation of synthetic liposomes by activated Bax and Bak. More recently, cholesterol, whose level is increased in most cancer cells, was shown to contribute to their resistance to cytotoxic stresses. Reducing cholesterol levels might therefore represent an interesting novel target to sensitize cancer cells to chemotherapeutic agents.     

Recombinant human hyaluronidase (rHuPH20): an enabling platform for subcutaneous drug and fluid administration

The extracellular matrix is a significant barrier to the effective subcutaneous delivery of many drugs, limiting both pharmacokinetic parameters and injection volumes. The space outside adipocytes in the hypodermis is not a fluid, but rather a solid extracellular matrix of collageneous fibrils embedded within a glycosaminoglycan-rich viscoelastic gel that buffers convective forces. The extracellular matrix limits the volume of drug that can be injected at a single site, as well as the rate and amount that reach the vascular compartment. A fully human recombinant DNA-derived hyaluronidase enzyme (rHuPH20) has been developed to leverage the historical efficacy of animal testes extract-derived spreading factors to reversibly modify the hypodermis, in light of discovery of the human hyaluronidase gene family. The application of this technology to increase both injection volumes and bioavailability from subcutaneous injection may overcome some key limitations of this route of administration in multiple settings of care.     

Recombinant human hyaluronidase (rHuPH20): an enabling platform for subcutaneous drug and fluid administration

The extracellular matrix is a significant barrier to the effective subcutaneous delivery of many drugs, limiting both pharmacokinetic parameters and injection volumes. The space outside adipocytes in the hypodermis is not a fluid, but rather a solid extracellular matrix of collageneous fibrils embedded within a glycosaminoglycan-rich viscoelastic gel that buffers convective forces. The extracellular matrix limits the volume of drug that can be injected at a single site, as well as the rate and amount that reach the vascular compartment. A fully human recombinant DNA-derived hyaluronidase enzyme (rHuPH20) has been developed to leverage the historical efficacy of animal testes extract-derived spreading factors to reversibly modify the hypodermis, in light of discovery of the human hyaluronidase gene family. The application of this technology to increase both injection volumes and bioavailability from subcutaneous injection may overcome some key limitations of this route of administration in multiple settings of care.     

PDBLIG: classification of small molecular protein binding in the Protein Data Bank

It is known that proteins can adopt different folds while sharing similar features for recognition of similar substrates or ligands, for example, in the binding sites of enzyme cofactors such as ATP. On the other hand, proteins that have highly flexible binding sites or belong to large and diverse protein families can bind structurally dissimilar ligands, as, for example, in the case of the matrix metalloprotease family. We have developed a database, PDBLIG, that classifies protein domains and ligands. The information stored includes each protein's function, domain class(es), which ligand(s) it binds, and so on. The database can provide valuable knowledge for drug discovery, supporting the answering of questions such as whether the same drug molecule can bind different target protein families and whether these families are related functionally or structurally, which ligand classes (such as metabolites or organic molecules) bind to a particular protein family and whether the ligands are druglike, and which target families bind a wide variety of ligands and whether different ligands are associated with different subfamilies.     

Insights into seven and single transmembrane-spanning domain receptors and their signaling pathways in human natural killer cells

Human natural killer (NK) cells are important cells of the innate immune system. These cells perform two prominent functions: the first is recognizing and destroying virally infected cells and transformed cells; the second is secreting various cytokines that shape up the innate and adaptive immune re-sponses. For these cells to perform these activities, they express different sets of receptors. The receptors used by NK cells to extravasate into sites of injury belong to the seven transmembrane (7TM) family of receptors, which characteristically bind heterotrimeric G proteins. These receptors allow NK cells to sense the chemotactic gradients and activate second messengers, which aid NK cells in polarizing and migrating toward the sites of injured tissues. In addition, these receptors determine how and why human resting NK cells are mainly found in the bloodstream, whereas activated NK cells extravasate into inflammatory sites. Receptors for chemokines and lysophospholipids belong to the 7TM family. On the other hand, NK cells recognize invading or transformed cells through another set of receptors that belong to the single transmembrane-spanning domain family. These receptors are either inhibitory or activating. Inhibitory receptors contain the immune receptor tyrosine-based inhibitory motif, and activating receptors belong to either those that associate with adaptor molecules containing the immune receptor tyrosine-based activating motif (ITAM) or those that associate with adaptor molecules containing motifs other than ITAM. This article will describe the nature of these receptors and examine the intracellular signaling pathways induced in NK cells after ligating both types of receptors. These pathways are crucial for NK cell biology, development, and functions.     

Fucan inhibits Chinese hamster ovary cell (CHO) adhesion to fibronectin by binding to the extracellular matrix

In recent years, sulfated fucans have emerged as an important class of natural biopolymers. In this study, the anti-adhesive activity of a fucan from the brown seaweed Spatoglossum schr?ederi was analyzed using tumorigenic cells: wild-type Chinese hamster ovary cells (CHO-K1) and the mutant type deficient in xylosyltransferase (CHO-745). Fibronectin (FN) was used as substrate for cell attachment. For both cell types, this fucan has shown a dose-dependent anti-adhesive effect, reaching saturation at around 400 mug/mL. This effect was abolished by desulfation of the fucan. In addition, this polymer exhibited the highest inhibitory effect in comparison to other sulfated polysaccharides. The fucan was biotinylated and used as a probe to identify its action sites. Biotinylated fucan was detected in the extracellular matrix environment by confocal microscopy and flow cytometric analysis, but not at the cell surface. The results suggest that the fucan shows anti-adhesive activity by binding directly to FN, and blocking FN sites that are recognized by cell surface ligands, possibly the integrin family.     

Zn2+ modulation of neurotransmitter transporters

Neurotransmitter transporters located at the presynaptic or glial cell membrane are responsible for the stringent and rapid clearance of the transmitter from the synapse, and hence they terminate signaling and control the duration of synaptic inputs in the brain. Two distinct families of neurotransmitter transporters have been identified based on sequence homology: (1) the neurotransmitter sodium symporter family (NSS), which includes the Na+/C1(-)-dependent transporters for dopamine, norepinephrine, and serotonin; and (2) the dicarboxylate/amino acid cation symporter family (DAACS), which includes the Na(+)-dependent glutamate transporters (excitatory amino acid transporters; EAAT). In this chapter, we describe how the identification of endogenous Zn2(+)-binding sites, as well as engineering of artificial Zn2(+)-binding sites both in the Na+/Cl(-)-dependent transporters and in the EAATs, have proved to be an important tool for studying the molecular function of these proteins. We also interpret the current available data on Zn2(+)-binding sites in the context of the recently published crystal structures. Moreover, we review how the identification of endogenous Zn2(+)-binding sites has indirectly suggested the possibility that several of the transporters are modulated by Zn2+ in vivo, and thus that Zn2+ can play a role as a neuromodulator by affecting the function of neurotransmitter transporters.     

Influence of Different Shellfish Matrices on the Separation of PSP Toxins Using a Postcolumn Oxidation Liquid Chromatography Method

The separation of PSP toxins using liquid chromatography with a post-column oxidation fluorescence detection method was performed with different matrices. The separation of PSP toxins depends on several factors, and it is crucial to take into account the presence of interfering matrix peaks to produce a good separation. The matrix peaks are not always the same, which is a significant issue when it comes to producing good, reliable results regarding resolution and toxicity information. Different real shellfish matrices (mussel, scallop, clam and oyster) were studied, and it was seen that the interference is not the same for each individual matrix. It also depends on the species, sampling location and the date of collection. It was proposed that separation should be accomplished taking into account the type of matrix, as well as the concentration of heptane sulfonate in both solvents, since the mobile phase varies regarding the matrix. Scallop and oyster matrices needed a decrease in the concentration of heptane sulfonate to separate GTX4 from matrix peaks, as well as dcGTX3 for oysters, with a concentration of 6.5 mM for solvent A and 6.25 mM for solvent B. For mussel and clam matrices, interfering peaks are not as large as they are in the other group, and the heptane sulfonate concentration was 8.25 mM for both solvents. Also, for scallops and oysters, matrix interferences depend not only on the sampling site but also on the date of collection as well as the species; for mussels and clams, differences are noted only when the sampling site varies.     

Cannabinoid receptors and their ligands: ligand-ligand and ligand-receptor modeling approaches

The cannabinoid CB1 and CB2 receptors belong to the class A, rhodopsin-like family of GPCRs. Antagonists for each receptor sub-type, as well as four structural classes of agonists that bind to both receptors, have been identified. An extensive amount of structure-activity relationship information (SAR) has been developed for agonists and antagonists that bind at CB1, while the SAR of CB2 ligands is only now emerging in the literature. This chapter focuses both on recent CB1 and CB2 SAR and on the pharmacophores for ligand recognition at the CB1 receptor that have been developed using ligand-ligand or ligand-receptor approaches. In a ligand-ligand approach, the structure of the binding site of the ligand is not directly considered. This approach is an attempt to infer information about the macromolecular binding site, and/or modes of binding interactions from a correlation between experimentally determined biological activities and the structural and electronic features of a series of small molecules. In a ligand-receptor approach, cannabinoid (CB) receptor models are probed for ligand binding sites and binding sites can be screened using energetic criteria, as well as ligand SAR and the CB mutation literature. This chapter discusses the factors that control the quality of the results emanating from each of these approaches and identifies areas of agreement and of disagreement in the existing CB literature. Challenges for future SAR and pharmacophore development are also identified.     

Interactions of the thymic polypeptide hormone thymopoietin with neuronal nicotinic alpha-bungarotoxin binding sites and with muscle-type, but not ganglia-type, nicotinic acetylcholine receptor ligand-gated ion channels.

Studies were conducted to assess the ability of the thymic polypeptide hormone thymopoietin (TPO) to interact with proto-typical ganglia-type or muscle-type nicotinic acetylcholine receptor ion channels (nAcChoR). Also investigated were interactions of TPO with neuronal nicotinic alpha-bungarotoxin binding sites (nBgtS), which share many features with nAcChoR and may belong to an extended nAcChoR family but do not appear to function as simple ligand-gated ion channels. TPO and alpha-bungarotoxin (Bgt) share the capacity for high affinity (IC50 values in the nanomolar range) interaction with nBgtS, which are expressed as high affinity radioiodinated Bgt binding sites by cells of the SH-SY5Y or IMR-32 human neuroblastomas. TPO and Bgt also share the capacity for high affinity interaction with muscle-type nAcChoR, which are expressed as high affinity binding sites for radioiodinated Bgt or tritium-labeled acetylcholine by cells of the TE671/RD human clone or the BC3H-1 mouse muscle cell line or on membrane preparations from Torpedo electroplax. TPO and Bgt act acutely as high affinity antagonists of muscle-type nAcChoR functional responses, which are measured using an isotopic rubidium ion efflux assay, on TE671/RD or BC3H-1 cells. In contrast, neither TPO nor Bgt are effective, at doses of up to 1 microM, as antagonists of ganglia-type nAcChoR function on SH-SY5Y or IMR-32 cells, nor are they potent as inhibitors of high affinity tritium-labeled acetylcholine binding to sites on putative ganglia-type nAcChoR expressed by SH-SY5Y or IMR-32 cells. These data indicate that some members of the extended nAcChoR family, including nBgtS and functional muscle-type nAcChoR but not ganglia-type nAcChoR, can interact with either Bgt or TPO. The results suggest that TPO may be an endogenous ligand active in both the nervous and immune systems and that some of its actions may be mediated via nBgtS or via functional blockade of muscle-type nAcChoR.     

Regenerating agents (RGTAs): a new therapeutic approach

RGTAs, or ReGeneraTing Agents constitute a new class of medicinal substance that enhance both speed and quality of tissue healing and leading in some case to a real tissue regenerating process. RGTAs consist of chemically engineered polymers adapted to interact with and protect against proteolytic degradation of cellular signaling proteins known as growth factors, cytokines, interleukins, colony stimulating factors, chemokines, neurotrophic factors etc. Indeed almost all these proteins of cellular communication are naturally stored in the extra cellular matrix interacting specifically with the heparan sulfates or HS. After tissue injury of any cause, cells die liberating glycanases and proteases inducing first HS degradation then liberation of the cytokines which in turn are susceptible to degradation as they are no longer protected. By replacing the natural HS, RGTAs will protect cytokines from proteolyses as they are liberated from the matrix compartment matter in the wound. This spatio-temporal selective protection of cytokines results in a preservation of the natural endogenous signaling of a tissue and is reflected by spectacular tissue regeneration or by a very greatly improved tissue repair. These observations indicate that mammals have an unexpected ability to regenerate and that RGTA helps to reveal this capacity. The aim of OTR3 is to develop RGTA into a drug to treat specific tissue lesions.     

How gene-stress-behavior interactions can promote adolescent alcohol use: the roles of predrinking allostatic load and childhood behavior disorders

A variety of environmental and genetic factors modulating the risk for alcoholism have been described, which predominantly act by interacting with each other. For example, the family, peers and society determine the level of exposure to stress and alcohol, while genes modulate how sensitive an individual responds to both. The resulting behaviors feed back to the social environment, modulating and in the worst case increasing further stress exposure. We here review neurobiological evidence how such a process of mutual interaction can involve and affect drinking. In at-risk adolescents it may have been in force for many years before they have their first alcoholic drink, increasing their risk for addiction by generating allostatic load. As an example, psychiatric disorders involving attention deficit, hyperactivity, or disruptive behaviors first evolve during childhood and are influenced by all the above factors. They are also strongly associated with harmful adolescent drinking and later alcohol use disorders. One important implication of this concept is that issues such as family adversity, adolescent psychiatric disorders, or adolescent drinking might not only be associated with, but causally related to, the risk for later addiction. They are targets for preventive interventions, which should start as early as possible in subjects at-risk.     

Fibroblasts and myofibroblasts: what are we talking about?

Cardiac myocytes, although large enough to make up most of the heart volume, are only a minority of cells within the heart with fibroblasts and blood vessel components (endothelial and smooth muscle cells) making up the remainder of the heart. In recent years, there has been increasing interest in the nonmyocyte population within the heart. This is attributable, in part, to our increasing understanding of the biology of the nonmyocyte cell types and additionally it is the result of our awakening realization that these cells are not static but rather that they are dynamic in nature indicating that they play a more active role in cardiac function than previously imagined. Studies now show that fibroblasts are involved in formation of the extracellular matrix and they control the size of the extracellular matrix. Additionally, they participate in the repair process by differentiating into myofibroblasts, which are cells involved in the inflammatory response to injury. Myofibroblasts migrate to the sites of injury where they produce cytokines, thus enhancing the inflammatory response. This review discusses both structural and functional differences between the two cell types and examines the different roles of these two different cell types in the heart.     

Huprine-tacrine heterodimers as anti-amyloidogenic compounds of potential interest against Alzheimer's and prion diseases

A family of huprine-tacrine heterodimers has been developed to simultaneously block the active and peripheral sites of acetylcholinesterase (AChE). Their dual site binding for AChE, supported by kinetic and molecular modeling studies, results in a highly potent inhibition of the catalytic activity of human AChE and, more importantly, in the in vitro neutralization of the pathological chaperoning effect of AChE toward the aggregation of both the β-amyloid peptide (Aβ) and a prion peptide with a key role in the aggregation of the prion protein. Huprine-tacrine heterodimers take on added value in that they display a potent in vitro inhibitory activity toward human butyrylcholinesterase, self-induced Aβ aggregation, and β-secretase. Finally, they are able to cross the blood-brain barrier, as predicted in an artificial membrane model assay and demonstrated in ex vivo experiments with OF1 mice, reaching their multiple biological targets in the central nervous system. Overall, these compounds are promising lead compounds for the treatment of Alzheimer's and prion diseases.     

An overall picture of chemokine receptors: basic research and drug development

Chemokine receptors belong to the transmembrane G protein coupled receptor (GPCR) family. Although a major physiological role of chemokine receptors is for host defense by recruitment of lymphocytes to inflammatory sites, they are now found to be involved in more processes such as virus infection, tumor genesis and metastasis, and embryologic development. In this review, we show an overall picture of chemokine receptors in structure, signal transduction and modulation, physiological and pathological roles, and applying chemokine receptors for drug discovery.