Viral Macrophage Inflammatory protein-II Research Articles

Multitargeted Immunomodulatory Therapy for Viral Myocarditis by Engineered Extracellular Vesicles.

Immune regulation therapies are considered promising for treating classically activated macrophage (M1)-driven viral myocarditis (VM). Alternatively, activated macrophage (M2)-derived extracellular vesicles (M2 EVs) have great immunomodulatory potential owing to their ability to reprogram macrophages, but their therapeutic efficacy is hampered by insufficient targeting capacity in vivo. Therefore, we developed cardiac-targeting peptide (CTP) and platelet membrane (PM)-engineered M2 EVs enriched with viral macrophage inflammatory protein-II (vMIP-II), termed CTP/PM-M2 EVsvMIP-II-Lamp2b, to improve the delivery of EVs "cargo" to the heart tissues. In a mouse model of VM, the intravenously injected CTP/PM-M2 EVsvMIP-II-Lamp2b could be carried into the myocardium via CTP, PM, and vMIP-II. In the inflammatory microenvironment, macrophages differentiated from circulating monocytes and macrophages residing in the heart showed enhanced endocytosis rates for CTP/PM-M2 EVsvMIP-II-Lamp2b. Subsequently, CTP/PM-M2 EVsvMIP-II-Lamp2b successfully released functional M2 EVsvMIP-II-Lamp2b into the cytosol, which facilitated the reprogramming of inflammatory M1 macrophages to reparative M2 macrophages. vMIP-II not only helps to increase the targeting ability of M2 EVs but also collaborates with M2 EVs to regulate M1 macrophages in the inflammatory microenvironment and downregulate the levels of multiple chemokine receptors. Finally, the cardiac immune microenvironment was protectively regulated to achieve cardiac repair. Taken together, our findings suggest that CTP-and-PM-engineered M2 EVsvMIP-II-Lamp2b represent an effective means for treating VM and show promise for clinical applications.

Effect of viral macrophage inflammatory protein II on the expression of APOBEC3G in 293T cells

Objective To assess the effect of viral macrophage inflammatory protein (vMIP) -Ⅱ on the expression of apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G) , and to explore the mechanisms. Methods A recombinant plasmid pEGFP-N3-K4 (vMIP-Ⅱ plasmid group) and an empty plasmid pEGFP-N3 (empty plasmid group) were separately transfected into 293T cells, and quantitative PCR and Western blot analysis were performed to evaluate the effect of transfection with vMIP-Ⅱ gene on the APOBEC3G expression in 293T cells. Some 293T cells in the empty plasmid group and vMIP-Ⅱ plasmid group were treated with 1 000 IU/ml interferon (IFN) -α for 36 hours, and then Western blot analysis was conducted to determine the APOBEC3G expression in the empty plasmid group and vMIP-Ⅱ plasmid group with or without IFN-α treatment. Some 293T cells transfected with vMIP-Ⅱ plasmids were treated with 75 μmol/L AG490 (a JAK/STAT signaling pathway inhibitor) and 20 μmol/L U0126 (an ERK signaling pathway inhibitor) separately; after 24 hours, total protein was extracted from 293T cells, and Western blot analysis was conducted to determine the expression of APOBEC3G. A recombinant plasmid containing APOBEC3G promoter was constructed by using a luciferase reporter gene, and the promoter fragment included the full-length promoter sequence (POS) of APOBEC3G, sequences with the lengths of 1 560, 960, 720, 480, 420, 360, 330 and 240 bp, and the regulatory element-free region (NEG) of APOBEC3G, separately. Some 293T cells were co-transfected with the recombinant plasmid carrying luciferase reporter gene and vMIP-Ⅱ plasmid (experimental group), or the recombinant plasmid and empty plasmid (control group). Subsequently, the activity of the APOBEC3G promoter was evaluated, and the key promoter region through which the transcriptional activity of APOBEC3G was regulated by vMIP-Ⅱ was analyzed. Statistical analysis was carried out by using t test, one-way analysis of variance and least significant difference (LSD) -t test. Results The mRNA and protein expression of APOBEC3G was significantly higher in the vMIP-Ⅱ plasmid group (2.500 ± 0.013, 1.472 ± 0.013 respectively) than in the control group (1, 0.364 ± 0.030 respectively; t = 6.22, 6.54 respectively, both P 0.05) . The APOBEC3G expression also significantly differed among the vMIP-Ⅱ plasmid group, vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱ plasmid + U0126 group (0.617 ± 0.025, 0.179 ± 0.061, 0.359 ± 0.012 respectively; F = 70.019, P < 0.001) , and was significantly lower in the vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱ plasmid + U0126 group than in the vMIP-Ⅱ plasmid group (t = 9.66, 11.836 respectively, both P < 0.01) . Luciferase activity assay showed that the promoter activity significantly differed among the vMIP-Ⅱ plasmid groups transfected with POS, 1 560-, 960-, 720-, 480-, 420-, 360-, 330-, 240-bp or NEG sequences (F = 81.092, P < 0.001) , and the APOBEC3G promoter activity decreased greatly from the 720-bp group to 480-bp group. Conclusion vMIP-Ⅱ upregulates the expression of APOBEC3G, likely through the JAK/STAT signaling pathway or the key promoter region regulating the transcriptional activity of APOBEC3G. Key words: HIV-1; Sarcoma, Kaposi; Luciferases; Viral macrophage inflammatory protein-Ⅱ; Anti-HIV genes; Apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G; JAK-STAT signaling pathway

Novel Bivalent and D-Peptide Ligands of CXCR4 Mobilize Hematopoietic Progenitor Cells to the Blood in C3H/HeJ Mice

The interaction of SDF-1α (also known as CXCL12) with the CXCR4 receptor plays a critical role in the retention of hematopoietic stem cells (HSCs) in bone marrow. The viral macrophage inflammatory protein-II (vMIP-II), a human herpesvirus-8 (HHV-8)-encoded viral chemokine, can bind the CXCR4 receptor and inhibit endogenous ligand-induced calcium responses and cell migration. Previously, we used the bivalent ligand approach to link synthetically two unnatural D-amino acid peptides derived from the N-terminus of vMIP-II (DV1 and DV3, respectively) to generate a dimeric peptide, DV1-K-(DV3) (also named HC4319), which shows very high affinity for CXCR4. Here, we studied the biological effects of this dimeric peptide, HC4319, and its monomeric counterpart, DV1, on SDF-1α-induced signaling in CXCR4- or CXCR7-transfected Chinese hamster ovary cells and mobilization of hematopoietic progenitor cells (HPCs) in C3H/HeJ mice using an HPC assay. HC4319 and DV1 inhibited significantly the phosphorylation of Akt and Erk, known to be downstream signaling events of CXCR4. This in vivo study in C3H/HeJ mice showed that HC4319 and DV-1 strongly induced rapid mobilization of granulocyte–macrophage colony-forming units (CFUs), erythrocyte burst-forming units, and granulocyte–erythrocyte–monocyte–megakaryocyte CFUs from the bone marrow to the blood. These results provide the first reported experimental evidence that bivalent and D-amino acid peptides derived from the N-terminus of vMIP-II are potent mobilizers of HPCs in C3H/HeJ mice and support the further development of such agents for clinical application.

Biophysical and Computational Studies of the vCCI:vMIP-II Complex.

Certain viruses have the ability to subvert the mammalian immune response, including interference in the chemokine system. Poxviruses produce the chemokine binding protein vCCI (viral CC chemokine inhibitor; also called 35K), which tightly binds to CC chemokines. To facilitate the study of vCCI, we first provide a protocol to produce folded vCCI from Escherichia coli (E. coli.) It is shown here that vCCI binds with unusually high affinity to viral Macrophage Inflammatory Protein-II (vMIP-II), a chemokine analog produced by the virus, human herpesvirus 8 (HHV-8). Fluorescence anisotropy was used to investigate the vCCI:vMIP-II complex and shows that vCCI binds to vMIP-II with a higher affinity than most other chemokines, having a Kd of 0.06 ± 0.006 nM. Nuclear magnetic resonance (NMR) chemical shift perturbation experiments indicate that key amino acids used for binding in the complex are similar to those found in previous work. Molecular dynamics were then used to compare the vCCI:vMIP-II complex with the known vCCI:Macrophage Inflammatory Protein-1β/CC-Chemokine Ligand 4 (MIP-1β/CCL4) complex. The simulations show key interactions, such as those between E143 and D75 in vCCI/35K and R18 in vMIP-II. Further, in a comparison of 1 μs molecular dynamics (MD) trajectories, vMIP-II shows more overall surface binding to vCCI than does the chemokine MIP-1β. vMIP-II maintains unique contacts at its N-terminus to vCCI that are not made by MIP-1β, and vMIP-II also makes more contacts with the vCCI flexible acidic loop (located between the second and third beta strands) than does MIP-1β. These studies provide evidence for the basis of the tight vCCI:vMIP-II interaction while elucidating the vCCI:MIP-1β interaction, and allow insight into the structure of proteins that are capable of broadly subverting the mammalian immune system.

PET/CT Imaging of Chemokine Receptors in Inflammatory Atherosclerosis Using Targeted Nanoparticles.

Atherosclerosis is inherently an inflammatory process that is strongly affected by the chemokine-chemokine receptor axes regulating the trafficking of inflammatory cells at all stages of the disease. Of the chemokine receptor family, some specifically upregulated on macrophages play a critical role in plaque development and may have the potential to track plaque progression. However, the diagnostic potential of these chemokine receptors has not been fully realized. On the basis of our previous work using a broad-spectrum peptide antagonist imaging 8 chemokine receptors together, the purpose of this study was to develop a targeted nanoparticle for sensitive and specific detection of these chemokine receptors in both a mouse vascular injury model and a spontaneously developed mouse atherosclerosis model. The viral macrophage inflammatory protein-II (vMIP-II) was conjugated to a biocompatible poly(methyl methacrylate)-core/polyethylene glycol-shell amphiphilic comblike nanoparticle through controlled conjugation and polymerization before radiolabeling with (64)Cu for PET imaging in an apolipoprotein E-deficient (ApoE(-/-)) mouse vascular injury model and a spontaneous ApoE(-/-) mouse atherosclerosis model. Histology, immunohistochemistry, and real-time reverse transcription polymerase chain reaction were performed to assess the plaque progression and upregulation of chemokine receptors. The chemokine receptor-targeted (64)Cu-vMIP-II-comb showed extended blood retention and improved biodistribution. PET imaging showed specific tracer accumulation at plaques in ApoE(-/-) mice, confirmed by competitive receptor blocking studies and assessment in wild-type mice. Histopathologic characterization showed the progression of plaque including size and macrophage population, corresponding to the elevated concentration of chemokine receptors and more importantly increased PET signals. This work provides a useful nanoplatform for sensitive and specific detection of chemokine receptors to assess plaque progression in mouse atherosclerosis models.

VCCL2/vMIP-II, the viral master KEYmokine.

Viral CC motif chemokine or viral macrophage inflammatory protein-II is 1 of the 3 chemokines encoded by the human herpesvirus-8 to interfere with the host chemokine receptor network, facilitate the immune escape, and promote its survival. Viral CC motif chemokine 2 binds to a broad spectrum of viral and human chemokine receptors of all 4 classes and, depending on the receptor, acts either as an agonist or an antagonist, inducing or blocking the recruitment of specific immune cell subsets. These atypical binding and signaling properties make this viral chemokine not only a useful tool to investigate the complexity of the chemokine-receptor interaction network or the virus-host interplay but also for the development of receptor inhibitors. This mini-review summarizes the knowledge currently available on viral CC motif chemokine 2 binding, signaling, and structural mimicry and discusses its role and importance for the virus, the therapeutic potential, and the open questions regarding the biology of this fascinating chemokine.

The Anti-inflammatory Effect of the CXCR4 Antagonist-N15P Peptide and Its Modulation on Inflammation-Associated Mediators in LPS-Induced PBMC.

Inflammation was the important pathological process of many disease developments, but current therapeutic means for inflammatory diseases are not satisfactory. Chemokines and their receptors represent valuable targets for anti-inflammatory drug discovery. The N15P polypeptide (sequence: LGASWHRPDKCCLGY) is independently developed by our research group, it is a new CXCR4 antagonist drug derived from viral macrophage inflammatory protein-II (vMIP-II). This study aims to clarify the anti-inflammatory potency of N15P polypeptide on the lipopolysaccharide (LPS)-induced inflammation in vitro. In this study, we evaluated the anti-inflammatory effects of N15P polypeptide by the LPS-induced peripheral blood mononuclear cell (PBMC) model and measured the level of inflammatory factors (tumor necrosis factor alpha (TNF-α), IL-6, IL-8, nuclear factor kappaB (NF-κB), cyclooxygenase-2 (COX-2), Toll-like receptor 4 (TLR4), MyD88, phosphoinositide 3-kinase (PI3K), and Akt). The messenger RNA (mRNA) expressions of inflammatory factors were analyzed by real-time PCR (RT-PCR) microarray analysis, and the production of inflammatory factors was measured further by enzyme-linked immunosorbent assay (ELISA) and Western blot. The results showed that the expression of inflammatory factors (TNF-α, IL-6, IL-8, NF-κB, COX-2, TLR4, MyD88, PI3K, and Akt) was downregulated by N15P peptide, suggesting that N15P peptide has a strong inhibitory effect on the inflammatory responses induced by LPS.

Synthetic Polypeptide Derived from Viral Macrophage Inflammatory Protein II Inhibit the Uninfected CD4&lt;sup&gt;+&lt;/sup&gt; T Cells Apoptosis Induced by HIV-1 Extracellular Nef

Purpose: To evaluate the potential role and cellular mechanism of the CXCR4 antagonist (N15P) derived from the N-terminal of viral macrophage inflammatory protein-II (vMIP-II) on the apoptosis induced by HIV-1 extracellular nef protein in vitro.Method: Peripheral blood mononuclear cells (PBMCs) and Jurkat cells were treated with HIV-1 nef protein alone or together with N15P at different doses and time points. The competitive binding effect of N15P against nef was assessed via radioligand binding assays. Apoptosis was evaluated via terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay. The level of nuclear FOXO3a and phospho-FOXO3a was assessed by Western blotting.Results: The interaction of 125I-nef with Jurkat cells was inhibited by N15P in a dose-dependent manner, with IC50 value of 0.3516 ng/ml. N15P protect against nef protein-induced apoptosis in a timeand concentration- dependent manner. The proapoptotic effect of extracellular nef protein in cells was associated with FOXO3a pathway and the changes in intracellular processes were blocked by N15P in a dose-dependent manner.Conclusion: N15P inhibits the apoptosis of uninfected CD4+ T lymphocytes induced by HIV-1 extracellular nef protein. Therefore, N15P is a potential effective CXCR4 antagonist in the course of HIV and could prevent or delay the onset of AIDS.Keywords: HIV-1, Nef, vMIP-II, Bystander lymphocytes, Apoptosis, FOXO3a, CXCR4 antagonist, Macrophage, Inflammation

A Comparison of 5P12-vMIP-II and vMIP-II as HIV-1 Entry Inhibitors

vMIP-II (viral macrophage inflammatory protein-II) is a chemokine analog expressed by human herpesvirus-8 that has the unique ability to bind multiple human chemokine receptors, including CCR5 and CXCR4, representative receptors of two major chemokine subfamilies. This broad binding ability gives vMIP-II powerful anti-inflammatory properties, which have been demonstrated in vitro and in vivo. In addition, vMIP-II is of great interest due to its ability to inhibit HIV infection by both major HIV strains: R5 (strains that enter the host cell using CCR5 as a co-receptor), and X4 (strains that use CXCR4). We have made a vMIP-II variant, “5P12-vMIP-II” in which the N-terminal amino acids of vMIP-II have been replaced by 10 amino acids that have been shown to greatly enhance the anti-HIV potency of the chemokine RANTES for R5 HIV strains. This 5P12-vMIP-II is shown by NMR to be fully folded and similar in structure to wild type vMIP-II. Both vMIP-II and 5P12-vMIP-II showed the ability to inhibit multiple strains of HIV, including several R5 strains and an X4 strain. While the 5P12 N-terminus did not improve the potency of the protein, our results suggest that vMIP-II does not bind CCR5 in the same way as human chemokines. Rather, vMIP-II has sacrificed some binding ability to particular chemokine receptors in order to obtain the ability to bind a broader array of receptors.

Engineering chemokines to develop putative anti HIV-1 agents

Background Even though, Highly Active Antiretroviral Therapy (HAART) has resulted in significant reduction in mortality associated with Acquired Immune Deficiency Syndrome (AIDS), the side-effects and difficulties in patient compliance warrants the search for new therapeutic options. One potential strategy is to design chemokine analogues that will prevent the entry of human immunodeficiency virus-1 (HIV-1) into the target cell by competitively blocking its interaction with CC chemokine-5 (CCR5) receptor. The objective of the present study is to design and validate the efficacy of chemokine analogues based on the viral macrophage inflammatory protein-II (vMIP-II) core as putative anti-HIV agents.

Characterization of the Interactions of vMIP-II, and a Dimeric Variant of vMIP-II, with Glycosaminoglycans

Chemokines are important immune proteins, carrying out their function by binding to glycosaminoglycans (GAGs) on the endothelial surface and to cell surface chemokine receptors. A unique viral chemokine analogue, viral macrophage inflammatory protein-II (vMIP-II), encoded by human herpesvirus-8, has garnered interest because of its ability to bind to multiple chemokine receptors, including both HIV coreceptors. In addition, vMIP-II binds to cell surface GAGs much more tightly than most human chemokines, which may be the key to its anti-inflammatory function in vivo. The goal of this work was to determine the mechanism of binding of GAG by vMIP-II. The interaction of vMIP-II with a heparin-derived disaccharide was characterized using NMR. Important binding sites were further analyzed by mutagenesis studies, in which corresponding vMIP-II mutants were tested for GAG binding ability using heparin chromatography and NMR. We found that despite having many more basic residues than some chemokines, vMIP-II shares a characteristic binding site similar to that of its human analogues, utilizing basic residues R18, R46, and R48. Interestingly, a particular mutation (Leu13Phe) caused vMIP-II to form a pH-dependent CC chemokine-type dimer as determined by analytical ultracentrifugation and NMR. To the best of our knowledge, this is the first example of engineering a naturally predominantly monomeric chemokine into a dissociable dimer by a single mutation. This dimeric vMIP-II mutant binds to heparin much more tightly than wild-type vMIP-II and provides a new model for studying the relationship between chemokine quaternary structure and various aspects of function. Structural differences between monomeric and dimeric vMIP-II upon GAG binding were characterized by NMR and molecular docking.

Viral macrophage inflammatory protein-II improves acute rejection in allogeneic rat kidney transplants

PurposeDuring rejection, leukocytes are recruited from the peripheral circulation into the graft leading to the damage of endothelial cells, capillary perfusion failure and graft loss. Chemokines play a pivotal role in the recruitment of leukocytes to the endothelium. Viral macrophage inflammatory protein-II (vMIP-II), a human herpes virus-8 DNA-encoded protein, is a broad-spectrum chemokine antagonist. The aim of the study was to prove the beneficial activity of vMIP-II treatment on acute rat kidney allograft damage.MethodsHeterotopic rat kidney transplantation was performed in the Fischer 344 to Lewis transplantation model and animals were treated with vMIP-II (2 × 15 µg or 100 µg/day) for 7 days. Rejection-induced damage was analyzed by histology, and microcirculatory changes within the graft were analyzed by in vivo microscopy.ResultsViral macrophage inflammatory protein-II significantly improved acute glomerular damage and tubulointerstitial inflammation and lowered the extent of vascular and tubulointerstitial damage of the treated allografts. Functional microcirculation of peritubular capillaries was significantly improved in vivo, and the firm adherence of leukocytes was significantly reduced by vMIP-II treatment.ConclusionsThe administration of the broad-spectrum antagonist vMIP-II improved acute renal allograft damage, mainly by a reduction in leukocyte recruitment with a subsequently improved renal cortical microcirculation in vivo.

Lentiviral Gene Delivery of vMIP-II to Transplanted Endothelial Cells and Endothelial Progenitors Is Proangiogenic In Vivo

Therapies that stimulate angiogenesis show promise in revascularization of transplanted or ischemic tissues. Viral macrophage inflammatory protein-II (vMIP-II) is encoded by human herpesvirus 8, and it can be both immunosuppressive and proangiogenic. However, little has been done to characterize the potential of vMIP-II-induced angiogenesis. We engineered a vMIP-II lentiviral gene vector, transduced both mature endothelial cells and progenitors, and transplanted these in Matrigel templates as an in vivo angiogenesis model. Our results show that vMIP-II promotes new, functional, branching, and segmented vessels associated with smooth muscle cells and connected with the host vasculature. Angiogenesis is enhanced through host cells as well as through transplanted vMIP-expressing endothelial cells. As a proof-of-concept for using vMIP-II in clinical applications, we showed that islets co-transplanted with endothelial cells expressing vMIP-II were revascularized and survived in Matrigel templates, whereas no islets survived under control conditions. vMIP-II up-regulates the expression of multiple proangiogenic factors that can have a synergistic effect. These include vascular endothelial growth factor (VEGF), kinase insert domain receptor, neuropilin 2, carcinoembryonic antigen-related cell adhesion molecule 1, interleukin-1alpha, fibronectin, and integrins alpha3, alpha4, and alpha5. These results provide the first demonstration that vMIP-II is proangiogenic in vivo and can deliver this function to endothelial progenitors as well as to mature endothelial cells through vector-mediated gene delivery.

Neuronal Apoptotic Signaling Pathways Probed and Intervened by Synthetically and Modularly Modified (SMM) Chemokines

As the main coreceptors for human immunodeficiency virus type 1 (HIV-1) entry, CXCR4 and CCR5 play important roles in HIV-associated dementia (HAD). HIV-1 glycoprotein gp120 contributes to HAD by causing neuronal damage and death, either directly by triggering apoptotic pathways or indirectly by stimulating glial cells to release neurotoxins. Here, to understand the mechanism of CXCR4 or CCR5 signaling in neuronal apoptosis associated with HAD, we have applied synthetically and modularly modified (SMM)-chemokine analogs derived from natural stromal cell-derived factor-1alpha or viral macrophage inflammatory protein-II as chemical probes of the mechanism(s) whereby these SMM-chemokines prevent or promote neuronal apoptosis. We show that inherently neurotoxic natural ligands of CXCR4, such as stromal cell-derived factor-1alpha or viral macrophage inflammatory protein-II, can be modified to protect neurons from apoptosis induced by CXCR4-preferring gp120(IIIB), and that the inhibition of CCR5 by antagonist SMM-chemokines, unlike neuroprotective CCR5 natural ligands, leads to neurotoxicity by activating a p38 mitogen-activated protein kinase (MAPK)-dependent pathway. Furthermore, we discover distinct signaling pathways activated by different chemokine ligands that are either natural agonists or synthetic antagonists, thus demonstrating a chemical biology strategy of using chemically engineered inhibitors of chemokine receptors to study the signaling mechanism of neuronal apoptosis and survival.

26. Lentiviral Vector Delivery of vMIP-II Using Both Transplanted Endothelial and Progenitor Cells Enhances a Robust and Functional Angiogenesis In Vivo

Therapies that stimulate angiogenesis are promising for revascularization of transplanted or ischemic tissues. Viral macrophage inflammatory protein-II (vMIP-II) is encoded by human herpesvirus 8 and may be both immunosuppressive and proangiogenic, though the latter is poorly characterized and only in vitro. We engineered a vMIP-II lentiviral gene vector, transduced both primary mature endothelial cells and progenitors, and transplanted these in Matrigel templates as an in vivo angiogenesis model.

SMM-Chemokines: A Class of Unnatural Synthetic Molecules as Chemical Probes of Chemokine Receptor Biology and Leads for Therapeutic Development

Chemokines and their receptors play important roles in numerous physiological and pathological processes. To develop natural chemokines into receptor probes and inhibitors of pathological processes, the lack of chemokine-receptor selectivity must be overcome. Here, we apply chemical synthesis and the concept of modular modifications to generate unnatural synthetically and modularly modified (SMM)-chemokines that have high receptor selectivity and affinity, and reduced toxicity. A proof of the concept was shown by transforming the nonselective viral macrophage inflammatory protein-II into new analogs with enhanced selectivity and potency for CXCR4 or CCR5, two principal coreceptors for human immunodeficiency virus (HIV)-1 entry. These new analogs provided insights into receptor binding and signaling mechanisms and acted as potent HIV-1 inhibitors. These results support the concept of SMM-chemokines for studying and controlling the function of other chemokine receptors.

NMR structures of anti-HIV d-peptides derived from the N-terminus of viral chemokine vMIP-II

The viral macrophage inflammatory protein-II (vMIP-II) encoded by Kaposi’s sarcoma-associated herpesvirus has unique biological activities in that it blocks the cell entry by several different human immunodeficiency virus type 1 (HIV-1) strains via chemokine receptors including CXCR4 and CCR5. In this paper, we report the solution structure of all- d-amino acid peptides derived from the N-terminus of vMIP-II, which have been shown to have strong CXCR4 binding activity and potently inhibit HIV-1 entry via CXCR4, by using long mixing time two-dimensional nuclear Overhauser enhancement spectroscopy experiments. Both of all- d-peptides vMIP-II (1–10) and vMIP-II (1–21), which are designated as DV3 and DV1, respectively, have higher CXCR4 binding ability than their l-peptide counterparts. They are partially structured in aqueous solution, displaying a turn-like structure over residues 5–8. The small temperature coefficients of His-6 amide proton for both peptides also suggest the formation of a small hydrophobic pocket centered on His-6. The structural features of DV3 are very similar to the reported solution structure of all- l-peptide vMIP-II (1–10) [M.P. Crump, E. Elisseeva, J. Gong, I. Clark-Lewis, B.D. Sykes, Structure/function of human herpesvirus-8 MIP-II (1–71) and the antagonist N-terminal segment (1–10), FEBS Lett. 489 (2001) 171], which is consistent with the notion that d- and l-enantiomeric peptides can adopt mirror image conformations. The NMR structures of the d-peptides provide a structural basis to understand their mechanism of action and design new peptidomimetic analogs to further explore the structure–activity relationship of d-peptide ligand binding to CXCR4.

Viral Macrophage-Inflammatory Protein-II: A Viral Chemokine That Differentially Affects Adaptive Mucosal Immunity Compared with Its Mammalian Counterparts

Chemokines play a profound role in leukocyte trafficking and the development of adaptive immune responses. Perhaps due to their importance in host defense, viruses have adopted many of the hallmarks displayed by chemokines. In particular, viral MIP-II (vMIP-II) is a human chemokine homologue that is encoded by human herpes virus 8. vMIP-II is angiogenic, selectively chemotactic for Th2 lymphocytes, and a homologue of human I-309 and mouse TCA-3, which also differentially attracts Th2 cells. To better understand the effect of viral chemokines on mucosal immunity, we compared the affects of vMIP-II, I-309, and TCA-3 on cellular and humoral immune responses after nasal immunization with OVA. These CCR8 ligands significantly enhanced Ag-specific serum and mucosal Abs through increasing Th2 cytokine secretion by CD4+ T cells. These alterations in adaptive humoral and cellular responses were preceded (12 h after immunization) by an increase in CD4+ T and B cells in nasal tracts with decreases of these leukocyte populations in the lung. Interestingly, vMIP-II increased neutrophil infiltration in the lung and Ag-specific IL-10-secreting CD4+ T cells after immunization. Although I-309 increased the number of CD28-, CD40L-, and CD30-positive, Ag-stimulated naive CD4+ T cells, vMIP-II and TCA-3 decreased the number of CD28-, CD40L-, and CD30-positive, resting naive CD4+ T cells. Taken together, these studies suggest that CCR8 ligands direct host Th2 responses, and vMIP-II up-regulates IL-10 responses and limits costimulatory molecule expression to mitigate host immunity.

Viral macrophage inflammatory protein-II and fractalkine (CX3CL1) chimeras identify molecular determinants of affinity, efficacy, and selectivity at CX3CR1.

Fractalkine (FKN/CX3CL1) is a cell surface-expressed chemokine involved in many aspects of leukocyte trafficking and activation. The various structural domains of FKN play distinct roles in its ability to bind and activate its receptor, CX3CR1. A human herpesvirus 8-encoded chemokine, termed viral macrophage inflammatory protein (vMIP)-II, is structurally similar to FKN; vMIP-II is a nonselective chemokine receptor antagonist (binding multiple chemokine receptors, including CX3CR1). The goal of this study was to identify FKN determinants of selectivity for its receptor and to further refine domains important in affinity and efficacy at CX3CR1. Chimeric and insertional mutagenesis was used to generate mutants of both vMIP-II and FKN, and the expressed proteins were evaluated for chemokine receptor binding affinities and efficacy at CX3CR1. Modification of the intervening amino acids between the first two conserved cysteine residues of FKN or vMIP-II indicated a role of the X3 bulge of FKN in affinity and selectivity for CX3CR1. Substitution of the vMIP-II N terminus with that of FKN created an agonist that was just as potent and efficacious as FKN for binding and stimulating CX3CR1, whereas replacement of the FKN N terminus with the cognate domain of vMIP-II disrupted the ability of FKN to bind CX3CR1. Furthermore, the entire N terminus of FKN was necessary for the high-affinity and full agonist properties of FKN at CX3CR1. These results refine the pharmacophore for chemokine binding to and activation of CX3CR1 and demonstrate the usefulness of modified virally encoded chemokines as templates for the development of selective chemokine receptor antagonists.

Chemokines and their receptors in the brain: Pathophysiological roles in ischemic brain injury

Chemokines constitute a large family of structurally-related small cytokines originally identified as factors regulating the migration of leukocytes in inflammatory and immune responses. Production of chemokines and their receptors in the brain has been reported under various pathological conditions. We revealed that mRNA expression for monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α), members of the CC chemokines, was induced in the rat brain after focal cerebral ischemia, and that intracerebroventricular injection of viral macrophage inflammatory protein-II (vMIP-II), a broad-spectrum chemokine receptor antagonist, reduced infarct volume in a dose-dependent manner. These findings suggest that brain chemokines are involved in ischemic injury, and that chemokine receptors are potential targets for therapeutic intervention in stroke. Another potential target to suppress the harmful effect of chemokines is the signal transmission system(s) regulating the chemokine production. However, very little is known about how the production of chemokines is regulated in the ischemic brain. We examined the induction of MCP-1 production by excitotoxic injury via activation of NMDA receptors in the cortico-striatal slice cultures, and found that excitotoxic injury induced MCP-1 production in the slice culture. Almost all of the MCP-1 immunoreactivity was located on astrocytes. On the other hand, NMDA-treatment failed to increase the MCP-1 production in the enriched astrocyte cultures, indicating that NMDA dose not directly act on astrocytes. Some signal(s) is likely sent from the injured neurons to astrocytes to induce the MCP-1 production. These results showed that organotypic slice cultures are useful to investigate the molecular mechanism regulating the chemokine production in the injured brain.