Nanoencapsulated rituximab mediates superior cellular immunity against metastatic B-cell lymphoma in a complement competent humanized mouse model.

BACKGROUND: Despite the numerous applications of monoclonal antibodies (mAbs) in cancer therapeutics, animal models available to test the therapeutic efficacy of new mAbs are limited. NOD.Cg-Prkdcscid Il2rg tm1Wjl /SzJ (NSG) mice are one of the most highly immunodeficient strains and are universally used as a model for testing cancer-targeting mAbs. However, this strain lacks several factors necessary to fully support antibody-mediated effector functions-including antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, and complement-dependent cytotoxicity (CDC)-due to the absence of immune cells as well as a mutation in the Hc gene, which is needed for a functional complement system. METHODS: We have developed a humanized mouse model using a novel NSG strain, NOD.Cg-Hc1Prkdcscid Il2rgtm1Wjl/SzJ (NSG-Hc1), which contains the corrected mutation in the Hc gene to support CDC in addition to other mechanisms endowed by humanization. With this model, we reevaluated the anticancer efficacies of nanoencapsulated rituximab after xenograft of the human Burkitt lymphoma cell line 2F7-BR44. RESULTS: As expected, xenografted humanized NSG-Hc1 mice supported superior lymphoma clearance of native rituximab compared with the parental NSG strain. Nanoencapsulated rituximab with CXCL13 conjugation as a targeting ligand for lymphomas further enhanced antilymphoma activity in NSG-Hc1 mice and, more importantly, mediated antilymphoma cellular responses. CONCLUSIONS: These results indicate that NSG-Hc1 mice can serve as a feasible model for both studying antitumor treatment using cancer targeting as well as understanding induction mechanisms of antitumor cellular immune response.

The evolution and functional characterization of CXC chemokines and receptors in lamprey.

Chemokines are a large family of soluble peptides guiding cell migration in development and immune defense. They interact with chemokine receptors and are essential for the coordination of cell migration in diverse physiological processes. The CXC subfamily is one of the largest groups in the chemokine family and consists of multiple members. In this study, we identified homologues of three chemokine ligands (CXCL8, CXCL_F5 and CXCL12) and two CXC receptor like molecules (CXCR_L1 and CXCR_L2) in lamprey. Sequence analysis revealed that they share the same genomic organization with their counterparts in jawed vertebrates but synteny was not conserved. Lamprey CXCL8 and CXCL12 have four conserved cysteine residues whilst the CXCL_F5 has two additional cysteine residues. In addition, CXCL_F5 is evolutionarily related to the fish specific CXC chemokine groups previously identified and contains multiple cationic aa residues in the extended C- terminal region. The two CXCRs possess seven transmembrane domains and conserved structural elements for receptor activation and signaling, including the DRYXXI(V)Y motif in TM2, the disulphide bond connecting ECL2 and TM3, the WXP motif in TM6 and NPXXY motif in TM7. The identified CXC chemokines and receptors were constitutively expressed in tissues including the liver, kidney, intestine, heart, gills, supraneural body and primary leukocytes, but exhibited distinct expression patterns. Relatively high expression was detected in the gills for CXCL8, CXCL_F5 and CXCR_L1 and in the supraneural body for CXCL12 and CXCR_L2. All the genes except CXCL12 were upregulated by stimulation with LPS, pokeweed and bacterial infection, and the CXCL8 and CXCL_F5 was induced by poly (I:C). Functional analysis showed that the CXCL8 and CXCL_F5 specifically interacted with CXCR_L1 and CXCR_L2, respectively. Our results demonstrate that the CXC chemokine system had diversified in jawless fish.

NMR and molecular modeling reveal specificity of the interactions between CXCL14 and glycosaminoglycans.

CXCL14, chemokine (C-X-C motif) ligand 14, is a novel highly conserved chemokine with unique features. Despite exhibiting the typical chemokine fold, it has a very short N-terminus of just two amino acid residues responsible for chemokine receptor activation. CXCL14 actively participates in homeostatic immune surveillance of skin and mucosae, is linked to metabolic disorders and fibrotic lung diseases and possesses strong anti-angiogenic properties in early tumor development. In this work, we investigated the interaction of CXCL14 with various glycosaminoglycans (GAGs) by nuclear magnetic resonance spectroscopy, microscale thermophoresis, analytical heparin (HE) affinity chromatography and in silico approaches to understand the molecular basis of GAG-binding. We observed different GAG-binding modes specific for the GAG type used in the study. In particular, the CXCL14 epitope for HE suggests a binding pose distinguishable from the ones of the other GAGs investigated (hyaluronic acid, chondroitin sulfate-A/C, -D, dermatan sulfate). This observation is also supported by computational methods that included molecular docking, molecular dynamics and free energy calculations. Based on our results, we suggest that distinct GAG sulfation patterns confer specificity beyond simple electrostatic interactions usually considered to represent the driving forces in protein-GAG interactions. The CXCL14-GAG system represents a promising approach to investigate the specificity of GAG-protein interactions, which represents an important topic for developing the rational approaches to novel strategies in regenerative medicine.

Antimicrobial and anti-inflammatory activities of chemokine CXCL14-derived antimicrobial peptide and its analogs.

CXCL14 is a CXC chemokine family that exhibits antimicrobial activity and contains an amphipathic cationic α-helical region in the C-terminus, a characteristic structure of antimicrobial peptides (AMPs). In this study, we designed three analogs of CXCL1459-75 (named CXCL14-C17) corresponding to the C-terminal α-helix of CXCL14, which displayed potential antimicrobial activity against a wide variety of gram-negative and gram-positive bacteria with minimum inhibitory concentrations of 4-16 µM without mammalian cell toxicity. Furthermore, two CXCL14-C17 analogs (CXCL14-C17-a1 and CXCL14-C17-a3) with improved cell selectivity were engineered by introducing Lys, Arg, or Trp in CXCL14-C17. Additionally, CXCL14-C17 analogs showed much greater synergistic effect (FICI: 0.3125-0.375) with chloramphenicol and ciprofloxacin against multidrug-resistant Pseudomonas aeruginosa (MDRPA) than LL-37 did (FICI: 0.75-1.125). CXCL14-C17 analogs were more active against antibiotic-resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA), MDRPA, and vancomycin-resistant Enterococcus faecium (VREF) than LL-37 and melittin. In particular, CXCL14-C17-a2 and CXCL14-C17-a3 completely inhibited the biofilm formation at sub-MIC and all of the peptides were able to eliminate pre-formed biofilm as well. Membrane depolarization, flow cytometry, sytox green uptake, ONPG hydrolysis and confocal microscopy revealed the possible target of the native peptide (CXCL14-C17) to likely be intracellular, and the amphipathic designed analogs targeted the bacterial membrane. CXCL14-C17 also showed DNA binding characteristic activity similar to buforin-2. Interestingly, CXCL14-C17-a2 and CXCL14-C17-a3 effectively inhibited the production and expression of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 from lipopolysaccharide (LPS)-stimulated RAW264.7 cells, suggesting that these peptides could be promising anti-inflammatory and antimicrobial agents.

Molecular cloning and biophysical characterization of CXCL3 chemokine.

CXCL3 is a neutrophil activating chemokine that belongs to GRO subfamily of CXC chemokines. GRO chemokine family comprises of three chemokines GRO α (CXCL1), GROß (CXCL2), and GRO γ (CXCL3), which arose as a result of gene duplication events during the course of chemokine evolution. Although primary sequences of GRO chemokines are highly similar, they performs several protein specific functions in addition to their common property of neutrophil trafficking. However, the molecular basis for their differential functions has not well understood. Although structural details are available for CXCL1 and CXCL2, no such information regarding CXCL3 is available till date. In the present study, we have successfully cloned, expressed, and purified the recombinant CXCL3. Around 15mg/L of pure recombinant CXCL3 protein was obtained. Further, we investigated its functional divergence and biophysical characteristics such as oligomerization, thermal stability and heparin binding etc., and compared all these features with its closest paralog CXCL2. Our studies revealed that, although overall structural and oligomerization features of CXCL3 and CXCL2 are similar, prominent differences were observed in their surface characteristics, thus implicating for a functional divergence.

The chemokinome superfamily in channel catfish: I. CXC subfamily and their involvement in disease defense and hypoxia responses.

Chemokines are a superfamily of structurally related chemotactic cytokines exerting significant roles in regulating cell migration and activation. They are defined by the presence of four conserved cysteine residues and are divided into four subfamilies depending on the arrangement of the first two conserved cysteines residues: CXC, CC, C and CX3C. In this study, a complete set of 17 CXC chemokine ligand (CXCL) genes was systematically identified and characterized from channel catfish genome through data mining of existing genomic resources. Phylogenetic analysis allowed annotation of the 17 CXC chemokines. Extensive comparative genomic analyses supported their annotations and orthologies, revealing the existence of fish-specific CXC chemokines and the expansion of CXC chemokines in the teleost genomes. The analysis of gene expression after bacterial infection indicated the CXC chemokines were expressed in a gene-specific manner. CXCL11.3 and CXCL20.3 were expressed significantly higher in resistant fish than in susceptible fish after ESC infection, while CXCL20.2 were expressed significantly higher in resistant fish than in susceptible fish after columnaris infection. The expression of those CXC chemokines, therefore can be a useful indicator of disease resistance. A similar pattern of expression was observed between resistant and susceptible fish with biotic and abiotic stresses, ESC, columnaris and hypoxia, suggesting that high levels of expression of the majority of CXC chemokines, with exception of CXC11 and CXC20, are detrimental to the host.

Efficient one-pot synthesis of CXCL14 and its derivative using an N-sulfanylethylanilide peptide as a peptide thioester equivalent and their biological evaluation.

CXCL14 is a CXC-type chemokine that exhibits chemotactic activity for immature dendritic cells, activated macrophages, and activated natural killer cells. However, its specific receptor and signaling pathway remain obscure. Recently, it was reported that CXCL14 binds to CXCR4 with high affinity and inhibits CXCL12-mediated chemotaxis. Furthermore, the CXCL14 C-terminal α-helical region is important for binding to its receptor. In this context, we chemically synthesized CXCL14 and its derivative with a one-pot method using N-sulfanylethylanilide peptide as a thioester equivalent. The synthetic CXCL14 proteins possessed inhibitory activities to CXCL12-mediated chemotaxis comparable with that of recombinant CXCL14. Moreover, we proved that chemically biotinylated CXCL14 binds to CXCR4 on cells by flow cytometry analysis.

CXCL14 displays antimicrobial activity against respiratory tract bacteria and contributes to clearance of Streptococcus pneumoniae pulmonary infection.

CXCL14 is a chemokine with an atypical, yet highly conserved, primary structure characterized by a short N terminus and high sequence identity between human and mouse. Although it induces chemotaxis of monocytic cells at high concentrations, its physiological role in leukocyte trafficking remains elusive. In contrast, several studies have demonstrated that CXCL14 is a broad-spectrum antimicrobial peptide that is expressed abundantly and constitutively in epithelial tissues. In this study, we further explored the antimicrobial properties of CXCL14 against respiratory pathogens in vitro and in vivo. We found that CXCL14 potently killed Pseudomonas aeruginosa, Streptococcus mitis, and Streptococcus pneumoniae in a dose-dependent manner in part through membrane depolarization and rupture. By performing structure-activity studies, we found that the activity against Gram-negative bacteria was largely associated with the N-terminal peptide CXCL141-13. Interestingly, the central part of the molecule representing the ß-sheet also maintained ∼62% killing activity and was sufficient to induce chemotaxis of THP-1 cells. The C-terminal α-helix of CXCL14 had neither antimicrobial nor chemotactic effect. To investigate a physiological function for CXCL14 in innate immunity in vivo, we infected CXCL14-deficient mice with lung pathogens and we found that CXCL14 contributed to enhanced clearance of Streptococcus pneumoniae, but not Pseudomonas aeruginosa. Our comprehensive studies reflect the complex bactericidal mechanisms of CXCL14, and we propose that different structural features are relevant for the killing of Gram-negative and Gram-positive bacteria. Taken together, our studies show that evolutionary-conserved features of CXCL14 are important for constitutive antimicrobial defenses against pneumonia.

Dimeric peptides of the C-terminal region of CXCL14 function as CXCL12 inhibitors.

We recently reported that CXCL14 binds to CXCR4 with high affinity and inhibits CXCL12-mediated chemotaxis. Here we found that the C-terminal 51-77 amino acid residues of CXCL14 are responsible for CXCR4 binding. A disulfide dimer peptide of CXCL14(51-77) bound to CXCR4 with comparable affinity to full length CXCL14, and exhibited CXCL12 inhibitor activity. CXCR4 was efficiently internalized upon binding of dimeric CXCL14(51-77), thereby being reduced on the cell surface. Substitution of 5 amino acid residues in combination with the use of an oxime linker for dimerization increased the solubility and chemical stability of the dimeric CXCL14(51-77).

Molecular characterisation and biological activity of a novel CXC chemokine gene in rock bream (Oplegnathus fasciatus).

Chemokines are chemoattractant cytokines defined by the presence of four conserved cysteine residues. In mammals, these cytokines can be divided into four subfamilies depending on the arrangement of the first two conserved cysteines in the sequence, and include the CXC(α), CC(ß), C(γ), and CX3C(δ) classes. We identified CXC chemokine cDNA, designated RbCXC, isolated using expressed sequence tag analysis of a lipopolysaccharide (LPS)-stimulated rock bream liver cDNA library. The full-length RbCXC cDNA (742 bp) contained an open reading frame of 342 bp encoding 114 amino acids. Results from phylogenetic analysis showed that RbCXC was strictly separated into a distinct clade compared to other known CXC chemokine subgroups. RbCXC was significantly expressed in the trunk kidney, liver, spleen, gill, peripheral blood leukocytes (PBLs), and head kidney. Rock bream PBLs were stimulated with several mitogens, including LPS and polyinosinic-polycytidylic acid (poly I:C), which significantly induced the expression of RbCXC mRNA. RbCXC mRNA expression was examined in several tissues under conditions of bacterial and viral challenge. Experimental challenges revealed that all examined tissues from fish infected with Edwardsiella tarda and red sea bream iridovirus showed significant increases in RbCXC expression compared to the control. In the case of Streptococcus iniae infection, RbCXC mRNA expression was markedly upregulated in the kidney, spleen, and liver. In addition, a maltose binding protein fusion recombinant RbCXC (~53 kDa) was produced in an Escherichia coli expression system and purified. Subsequently, the addition of purified recombinant RbCXC (rRbCXC) to kidney leukocytes was examined to investigate the impact of proliferative and chemotactic activity. The rRbCXC induced significant kidney leukocyte proliferation and attraction at concentrations ranging from 10 to 300 µg/mL, suggesting that it can be utilised as an immune stimulant and/or molecular adjuvant to enhance the immunological effects of vaccines.

An N-terminally truncated mutant of human chemokine CXCL14 has biological activity.

Chemokines are members of the superfamily of cytokines involved in: (i) cell migration to sites of infection; or (ii) cellular stress during an immune response. Human CXCL14/BRAK is a monocyte-selective chemokine expressed in all normal tissues, but is also involved in the development of several cancers. We describe the expression, structural characterization and biological activity of an N-terminal truncated mutant of CXCL14, ΔCXCL14, where the first eleven residues and the two disulphide bridges were removed. We designed this species in order to analyse the biological importance of the disulphide bonds and the flexible N terminus of CXCL14 for its protein folding, stability and function. The mutant ΔCXCL14 is biologically active, as suggested by the in vitro assays with migration of pancreatic cancer cells, but also its structure is not well-fixed, as suggested by fluorescence, CD and NMR. We conclude that the disulphide bridges are important in maintaining the structure of this chemokine, but they are not necessary for the biological activity of CXCL14 species.

Collagen IV and CXC chemokine-derived antiangiogenic peptides suppress glioma xenograft growth.

Peptides are receiving increasing attention as therapeutic agents due to their high binding specificity and versatility to be modified as targeting or carrier molecules. Particularly, peptides with antiangiogenic activity are of high interest because of their applicability to a wide range of cancers. In this study, we investigate the biological activity of two novel antiangiogenic peptides in preclinical glioma models. One peptide SP2000 is derived from collagen IV and the other peptide SP3019 belongs to the CXC family. We have previously characterized the capacity of SP2000 and SP3019 to inhibit multiple biological endpoints linked to angiogenesis in human endothelial cells in several assays. Here, we report additional studies using endothelial cells and focus on the activity of these peptides against human glioma cell growth, migration and adhesion in vitro, and growth as tumor xenografts in vivo. We found that SP2000 completely inhibits migration of the glioma cells at 50 µmol/l and SP3019 produced 50% inhibition at 100 µmol/l. Their relative antiadhesion activities were similar, with SP2000 and SP3019 generating 50% adhesion inhibition at 4.9 ± 0.82 and 21.3 ± 5.92 µmol/l, respectively. In-vivo glioma growth inhibition was 63% for SP2000 and 76% for SP3019 after 2 weeks of administration at daily doses of 10 and 20 mg/kg, respectively. The direct activity of these peptides against glioma cells in conjunction with their antiangiogenic activities warrants their further development as either stand-alone agents or in combination with standard cytotoxic or emerging targeted therapies in malignant brain tumors.

Monitoring serum levels ELR+ CXC chemokines and the relationship between microvessel density and angiogenic growth factors in multiple myeloma.

BACKGROUND: The ELR+ CXC chemokines are important mediators of tumorigenesis, related to their angiogenic properties. Angiogenesis appears to be a prominent feature in the progression of multiple myeloma (MM). CXC chemokines have four highly conserved cysteine amino acid residues, with the first two cysteine molecules separated by a single amino acid. The angiogenic potential of this group is determined by the presence of three amino acid residues (Glu-Leu-Arg: the ELR motif) preceding the first cysteine amino acid, in the NH2 terminus. AIMS: The purpose of this study was to determine serum concentrations of angiogenesis-related chemokines ELR+ motif, such as interleukin-8 (IL-8), epithelial neutrophil activating protein-78 (ENA-78) and growth-related gene alpha (GRO-α), as well the bone marrow microvascular density (MVD) in patients with MM at diagnosis and after treatment, in plateau phase. We also evaluated the relationship among them with other known growth factors involved in angiogenesis. METHODS: Serum levels of the ELR+ CXC chemokines: IL-8, ENA-78 and GRO-α as well as of the angiogenic factors: hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and tumor necrosis factor-α (TNF-α) were determined in 63 newly diagnosed MM patients, in 30 in plateau phase and in 20 healthy controls. Serum measurements of them were performed with commercially available kits for ELISA. Bone marrow biopsies were performed before and after treatment, in plateau phase, in order to determine MVD by staining vessels with anti-CD31. RESULTS: Serum concentrations of IL-8, ENA-78, GRO-α and TNF-α were significantly higher in the group of MM patients (44.5±25.3, 765±572.1, 186.5±129.1 and 4.2±2.8 pg/ml, respectively) in comparison to control group (27.3±6.4, 335.1±268.6, 112.5±76.1 and 1.3±0.8 pg/ml) (p<0.02 for GRO-α, p<0.001 for other cases). We also found that untreated patients had higher levels of IL-8, ENA-78, GRO-α than post treatment patients, but statistical significant difference was found only for IL-8 (48.36±30.93 pg/ml vs. 35.05±19.77 pg/ml, p<0.001). Furthermore IL-8, GRO-α, TNF-α, HGF and VEGF were significantly higher with increasing disease stage (p<0.001 in all cases). ENA-78 serum levels were higher in stage III than in stage I and II, but without statistical significance. Additionally we correlated each proinflammatory cytokine with well known angiogenic factors such as HGF, VEGF and TNF-α. A positive correlation was found between serum HGF and IL-8 and GRO-α (r=0.316 p<0.01, r=0.297 p<0.02, respectively). Similarly serum VEGF correlated with ENA-78 and GRO-α (r=0.323 p<0.01, r=0.469 p<0.001, respectively). In the pretreatment group of patients a positive correlation between bone marrow MVD and serum levels of GRO-α was found (r=0.304 p<0.01). There was a difference in survival times between patients with higher than median versus low IL-8, ENA-78 and GRO-α levels, but the differences could not reach statistical significance in either case. CONCLUSIONS: These findings support the hypothesis that ELR+ motif CXC chemokines, such as IL-8, ENA-78 and GRO-α correlate with angiogenic growth factors and may play a role in the progression of MM. Further studies are needed to determine their prognostic and predictive significance.

Sulfotyrosine recognition as marker for druggable sites in the extracellular space.

Chemokine signaling is a well-known agent of autoimmune disease, HIV infection, and cancer. Drug discovery efforts for these signaling molecules have focused on developing inhibitors targeting their associated G protein-coupled receptors. Recently, we used a structure-based approach directed at the sulfotyrosine-binding pocket of the chemokine CXCL12, and thereby demonstrated that small molecule inhibitors acting upon the chemokine ligand form an alternative therapeutic avenue. Although the 50 members of the chemokine family share varying degrees of sequence homology (some as little as 20%), all members retain the canonical chemokine fold. Here we show that an equivalent sulfotyrosine-binding pocket appears to be conserved across the chemokine superfamily. We monitored sulfotyrosine binding to four representative chemokines by NMR. The results suggest that most chemokines harbor a sulfotyrosine recognition site analogous to the cleft on CXCL12 that binds sulfotyrosine 21 of the receptor CXCR4. Rational drug discovery efforts targeting these sites may be useful in the development of specific as well as broad-spectrum chemokine inhibitors.

Application of N-C- or C-N-directed sequential native chemical ligation to the preparation of CXCL14 analogs and their biological evaluation.

CXCL14 is a chemokine that exhibits chemoattractant activity for activated macrophages, immature dendric cells, natural killer cells, and epithelial tumor cells. Its potential role as a metabolic regulator has recently been disclosed. However, a complete understanding of its physiological roles remains elusive. This is partly due to the lack of appropriate CXCL14-based molecular probes to explore the biological functions of CXCL14. In this context, we have developed synthetic protocols that provide access to a wide variety of CXCL14 analogs. Two sequential native chemical ligation (NCL) protocols, which proceed in opposite directions, have been used to assemble CXCL14 analogs from peptide fragments. The first involved a conventional C-N-directed sequential NCL, and afforded wild-type CXCL14. The other used peptide thioacids in N-C-directed elongation, and yielded CXCL14 analogs with molecular diversity at the C-terminal fragment. The CXCL14 analogs prepared showed biological activity on human monocytic leukemia-derived THP-1 cells that was comparable to that of wild-type CXCL14.

Peptides derived from type IV collagen, CXC chemokines, and thrombospondin-1 domain-containing proteins inhibit neovascularization and suppress tumor growth in MDA-MB-231 breast cancer xenografts.

Angiogenesis or neovascularization, the process of new blood vessel formation from preexisting microvasculature, involves interactions among several cell types including parenchymal, endothelial cells, and immune cells. The formation of new vessels is tightly regulated by a balance between endogenous proangiogenic and antiangiogenic factors to maintain homeostasis in tissue; tumor progression and metastasis in breast cancer have been shown to be angiogenesis-dependent. We previously introduced a systematic methodology to identify putative endogenous antiangiogenic peptides and validated these predictions in vitro in human umbilical vein endothelial cell proliferation and migration assays. These peptides are derived from several protein families including type IV collagen, CXC chemokines, and thrombospondin-1 domain-containing proteins. On the basis of the results from the in vitro screening, we have evaluated the ability of one peptide selected from each family named pentastatin-1, chemokinostatin-1, and properdistatin, respectively, to suppress angiogenesis in an MDA-MB-231 human breast cancer orthotopic xenograft model in severe combined immunodeficient mice. Peptides were administered intraperitoneally once per day. We have demonstrated significant suppression of tumor growth in vivo and subsequent reductions in microvascular density, indicating the potential of these peptides as therapeutic agents for breast cancer.

Functional characterization of the ELR motif in piscine ELR+CXC-like chemokine.

To elucidate the functional role of piscine incomplete ELR motif, the recombinant CXC and its mutants (mELR and mLoop) were produced in Escherichia coli M15 based on the predicted mature peptide coding sequence of the black sea bream CXC (BS CXC) chemokine. Assays showed that the BS rCXC proteins displayed strong ability to induce fish blood neutrophils and head kidney (HK) macrophage migration in a dose-independent manner (10 to 200 ng), both in black sea bream and common carp. Although the ELR motif and the N-terminal loop of ELR(+)CXC chemokines are essential for chemotactic activity and receptor binding in mammals, the mELR and mLoop mutants showed no significant difference in their induction of chemotaxis of fish blood neutrophils compared with the full-length rCXC at the same dose. Human recombinant IL-8 (hrIL-8) can clearly induce piscine blood neutrophil migration and has no effect on macrophages, whereas the BS rCXC cannot induce chemotaxis in higher vertebrates, such as rat blood neutrophils or macrophages, even if the incomplete ELR motif in rCXC was mutated to ELR. The BS CXC and its mutants can promote the phagocytosis ability of piscine blood neutrophils and HK macrophages both in black sea bream and common carp, but have no effect on rat neutrophils or macrophages. Results showed that the piscine ELR(+)CXC-like chemokine represents an ancient version of a CXC chemokine; the ELR motif still does not show the higher specific polarization of function as found in mammalian.

Growth related oncogene-alpha (GRO-alpha): roles in atherosclerosis, angiogenesis and other inflammatory conditions.

Growth related oncogene-alpha (GRO-alpha) is a member of the CXC chemokine family with an internal glutamate-leucine-arginine (ELR) motif. It was initially isolated and characterized by its growth stimulatory activity on malignant melanoma cells. Recently, many new functions and properties of GRO-alpha have been discovered and associated with atherosclerosis, angiogenesis and many inflammatory conditions. Purpose of this review is to overview current advances of multiple functions of GRO-alpha and its associated molecular mechanisms and clinical implications. We hope to further evaluate this molecule in the pathogenesis of atherosclerosis as well as angiogenesis to promote a background for therapeutic interventions.

Structural and functional basis of CXCL12 (stromal cell-derived factor-1 alpha) binding to heparin.

CXCL12 (SDF-1alpha) and CXCR4 are critical for embryonic development and cellular migration in adults. These proteins are involved in HIV-1 infection, cancer metastasis, and WHIM disease. Sequestration and presentation of CXCL12 to CXCR4 by glycosaminoglycans (GAGs) is proposed to be important for receptor activation. Mutagenesis has identified CXCL12 residues that bind to heparin. However, the molecular details of this interaction have not yet been determined. Here we demonstrate that soluble heparin and heparan sulfate negatively affect CXCL12-mediated in vitro chemotaxis. We also show that a cluster of basic residues in the dimer interface is required for chemotaxis and is a target for inhibition by heparin. We present structural evidence for binding of an unsaturated heparin disaccharide to CXCL12 attained through solution NMR spectroscopy and x-ray crystallography. Increasing concentrations of the disaccharide altered the two-dimensional (1)H-(15)N-HSQC spectra of CXCL12, which identified two clusters of residues. One cluster corresponds to beta-strands in the dimer interface. The second includes the amino-terminal loop and the alpha-helix. In the x-ray structure two unsaturated disaccharides are present. One is in the dimer interface with direct contacts between residues His(25), Lys(27), and Arg(41) of CXCL12 and the heparin disaccharide. The second disaccharide contacts Ala(20), Arg(21), Asn(30), and Lys(64). This is the first x-ray structure of a CXC class chemokine in complex with glycosaminoglycans. Based on the observation of two heparin binding sites, we propose a mechanism in which GAGs bind around CXCL12 dimers as they sequester and present CXCL12 to CXCR4.

Probing nascent structures in peptides using natural abundance 13C NMR relaxation and reduced spectral density mapping.

The main chain motional properties for a series of peptides that appear to have preferred conformations in solution have been systematically studied using solution-state nuclear magnetic resonance spectroscopy. The series of peptides were derived from the N-termini of pro-inflammatory chemokine proteins and HoxB1, a transcriptional regulator. As an unstructured control, a ten residue peptide was designed, synthesized, and found to be minimally structured from solution NMR data. The dynamic properties of the main chain for the peptides were assessed through longitudinal and transverse main chain (13)Calpha relaxation rates and the heteronuclear nuclear Overhauser effect. Motional parameters were interpreted using reduced spectral density mapping and compared with those derived from an extended Lipari-Szabo model in which the rotational correlation time was calculated for each main chain site of the peptide. Comparison of spectral density and Lipari-Szabo analyses for the peptides to those of the unstructured control peptide reveals significant differences in the dynamic behavior of the peptides. The amplitude of picosecond to nanosecond timescale motions for the main chain is observed to decrease for all of the chemokine peptides and HoxB1 over the regions that show partial structure at low temperatures. Comparatively, changes in picosecond to nanosecond timescale motions for the unstructured control peptide show no correlation with sequence position. These results indicate that there are distinguishable low temperature motional differences between an intrinsically unstructured peptide and peptides that have an inherent propensity to structure.