Evasins: Therapeutic Potential of a New Family of Chemokine-Binding Proteins from Ticks

Blood sucking parasites such as ticks remain attached to their hosts for relatively long periods of time in order to obtain their blood meal without eliciting an immune response. One mechanism used to avoid rejection is the inhibition of the recruitment of immune cells, which can be achieved by a class of chemokine binding proteins (CKBPs) known as Evasins. We have identified three distinct Evasins produced by the salivary glands of the common brown dog tick, Rhipicephalus sanguineus. They display different selectivities for chemokines, the first two identified show a narrow selectivity profile, whilst the third has a broader binding spectrum. The Evasins showed efficacy in several animal models of inflammatory disease. Here we will discuss the potential of their development for therapeutic use, addressing both the advantages and disadvantages that this entails

Leukocyte adhesion: reconceptualizing chemokine presentation by glycosaminoglycans

Recruitment of immune cells from the vasculature relies on the presentation of glycosaminoglycan-bound chemokines on the luminal side of vascular endothelial cells. However, the current model of chemokine–glycosaminoglycan interactions, and its implications for receptor interactions, remains poorly developed. We propose a refined ‘Chemokine Cloud’ model, arguing that chemokines are not presented to leukocytes bound to glycosaminoglycans, but rather, in solution while sequestered within the hydrated glycocalyx. We posit that glycosaminoglycans provide an immobilized chemokine depot maintaining a ‘cloud’ of ‘solution-phase’ chemokines within the glycocalyx, and that it is this soluble form of any given chemokine that interacts with leukocyte-bound receptors. Our proposition clarifies certain anomalies associated with the current model of chemokine–glycosaminoglycan interactions, with implications for the design of blockers of chemokine function

Modulation of chemokine responses: synergy and cooperativity

Chemokine biology is mediated by more complex interactions than simple monomolecular ligand–receptor interactions, as chemokines can form higher order quaternary structures, which can also be formed after binding to glycosaminoglycans (GAGs) on endothelial cells, and their receptors are found as dimers and/or oligomers at the cell surface. Due to the complexity of the chemokine binding and signaling system, several mechanisms have been proposed to provide an explanation for the synergy observed between chemokines in leukocyte migration. Pioneering studies on interactions between different chemokines have revealed that they can act as antagonists, or synergize with other chemokines. The synergism can occur at different levels, involving either two chemokine receptors triggered simultaneously or sequentially exposed to their agonists, or the activation of one type of chemokine receptor triggered by chemokine heterocomplexes. In addition to the several chemokines that, by forming a heterocomplex with chemokine receptor agonists, act as enhancers of molecules of the same family, we have recently identified HMGB1, an endogenous damage-associated molecular patterns (DAMPs) molecule, as an enhancer of the activity of CXCL12. It is now evident that synergism between chemokines is crucial at the very early stage of inflammation. In addition, the low-affinity interaction with GAGs has recently been shown to induce cooperativity allowing synergy or inhibition of activity by displacement of other ligands

Методичні рекомендації щодо проходження науково-практичної підготовки магістрів спеціальності 8.05030101 Розробка родовищ та видобування корисних копалин

Подано методичні матеріали щодо проходження науково-практичної підготовки з освітньо-кваліфікаційної програми магістрів спеціальності 8.05030101 Розробка родовищ та видобування корисних копалин

Structural Basis of Chemokine Sequestration by a Tick Chemokine Binding Protein: The Crystal Structure of the Complex between Evasin-1 and CCL3

Chemokines are a subset of cytokines responsible for controlling the cellular migration of inflammatory cells through interaction with seven transmembrane G protein-coupled receptors. The blocking of a chemokine-receptor interaction results in a reduced inflammatory response, and represents a possible anti-inflammatory strategy, a strategy that is already employed by some virus and parasites. Anti-chemokine activity has been described in the extracts of tick salivary glands, and we have recently described the cloning and characterization of such chemokine binding proteins from the salivary glands, which we have named Evasins.We have solved the structure of Evasin-1, a very small and highly selective chemokine-binding protein, by x-ray crystallography and report that the structure is novel, with no obvious similarity to the previously described structures of viral chemokine binding proteins. Moreover it does not possess a known fold. We have also solved the structure of the complex of Evasin-1 and its high affinity ligand, CCL3. The complex is a 1:1 heterodimer in which the N-terminal region of CCL3 forms numerous contacts with Evasin-1, including prominent pi-pi interactions between residues Trp89 and Phe14 of the binding protein and Phe29 and Phe13 of the chemokine.However, these interactions do not appear to be crucial for the selectivity of the binding protein, since these residues are found in CCL5, which is not a ligand for Evasin-1. The selectivity of the interaction would appear to lie in the N-terminal residues of the chemokine, which form the "address" whereas the hydrophobic interactions in the rest of the complex would serve primarily to stabilize the complex. A thorough understanding of the binding mode of this small protein, and its other family members, could be very informative in the design of potent neutralizing molecules of pro-inflammatory mediators of the immune system, such as chemokines

Role of the chemokines CCL3/MIP-1α and CCL5/RANTES in sponge-induced inflammatory angiogenesis in mice

Barcelos, Luciola S Coelho, Amanda M Russo, Remo C Guabiraba, Rodrigo Souza, Adriano L S Bruno-Lima, Guilherme Jr Proudfoot, Amanda E I Andrade, Silvia P Teixeira, Mauro M Microvasc Res. 2009 Sep;78(2):148-54. doi: 10.1016/j.mvr.2009.04.009. Epub 2009 May 8.; International audience; OBJECTIVE: We examined the potential contribution of CCL3 and CCL5 to inflammatory angiogenesis in mice. METHODS: Polyester-polyurethane sponges were implanted in mice and blood vessel counting and hemoglobin, myeloperoxidase and N-acetylglucosaminidase measurements used as indexes for vascularization, neutrophil and macrophage accumulation, respectively. RESULTS: CCL3 and CCL5 were expressed throughout the observation period. Exogenous CCL3 enhanced angiogenesis in WT, but angiogenesis proceeded normally in CCL3(-/-) mice, suggesting that endogenous CCL3 is not critical for sponge-induced angiogenesis in mice. CCL5 expression was detected at day 1, but levels significantly increased thereafter. Exogenous CCL5 reduced angiogenesis in WT mice possible via CCR5 as CCL5 was without an effect in CCR5(-/-) mice. Treatment of WT with the CCR1/CCR5 antagonist, Met-RANTES, prevented neutrophil and macrophage accumulation, but enhanced sponge vascularization. CONCLUSION: Thus, endogenous CCL3 appears not to play a role in driving sponge-induced inflammatory angiogenesis in mice. The effects of CCL5 were anti-angiogenic and appeared to be mediated via activation of CCR5

Interference with Oligomerization and Glycosaminoglycan Binding of the Chemokine CCL5 Improves Experimental Liver Injury

Background: The chemokine CCL5 is involved in the recruitment of immune cells and a subsequent activation of hepatic stellate cells (HSC) after liver injury. We here investigate whether inhibition of CCL5 oligomerization and glycosaminoglycan binding by a mutated CCL5 protein ( 44 AANA 47-CCL5) has the potential to ameliorate liver cell injury and fibrosis in vivo. Methodology: Liver injury was induced in C57BL/6 mice by intraperitoneal injection of carbon tetrachloride (CCl4) inan acute and a chronic liver injury model. Simultaneously, mice received either 44 AANA 47-CCL5 or vehicle. Liver cell necrosis and fibrosis was analyzed by histology, and measurement of serum transaminases and hydroxyproline. Intrahepatic mRNA expression of fibrosis and inflammation related genes were determined by quantitative RT-PCR and infiltration of immune cells was assessed by FACS analysis and immunocytochemistry. In vitro, HSC were stimulated with conditioned media of T-cell enriched splenocytes. Principal Findings: 44 AANA 47-CCL5 treated mice displayed a significantly reduced degree of acute liver injury (liver cell necrosis, transaminases) and fibrosis (Sirus red positive area and hydroxyproline content) compared to vehicle treated mice. Ameliorated fibrosis by 44 AANA 47-CCL5 was associated with a decreased expression of fibrosis related genes, decreased a-smoth muscle antigen (aSMA) and a reduction of infiltrating immune cells. In the acute model, 44 AANA 47-CCL5 treated mice displayed a reduced immune cell infiltration and mRNA levels of TNF, IL-1 and CCL3 compared to vehicle treated mice. I