Assessment of protein biomarkers for preoperative differential diagnosis between benign and malignant ovarian tumors

OBJECTIVE

To estimate the diagnostic value of tumor and immune related proteins in the discrimination between benign and malignant adnexal masses, and between different subgroups of tumors.

METHODS

In this exploratory diagnostic study, 254 patients with an adnexal mass scheduled for surgery were consecutively enrolled at the University Hospitals Leuven (128 benign, 42 borderline, 22 stage I, 55 stage II-IV, and 7 secondary metastatic tumors). The quantification of 33 serum proteins was done preoperatively, using multiplex high throughput immunoassays (Luminex) and electrochemiluminescence immuno-assay (ECLIA). We calculated univariable areas under the Receiver Operating Characteristic Curves (AUCs). To discriminate malignant from benign tumors, multivariable ridge logistic regression with backward elimination was performed, using bootstrapping to validate the resulting AUCs.

RESULTS

CA125 had the highest univariable AUC to discriminate malignant from benign tumors (0.85, 95% confidence interval 0.79-0.89). Combining CA125 with CA72.4 and HE4 increased the AUC to 0.87. For benign vs borderline tumors, CA125 had the highest univariable AUC (0.74). For borderline vs stage I malignancy, no proteins were promising. For stage I vs II-IV malignancy, CA125, HE4, CA72.4, CA15.3 and LAP had univariable AUCs ≥0.80.

CONCLUSIONS

The results confirm the dominant role of CA125 for identifying malignancy, and suggest that other markers (HE4, CA72.4, CA15.3 and LAP) may help to distinguish between stage I and stage II-IV malignancies. However, further research is needed, also to investigate the added value over clinical and ultrasound predictors of malignancy, focusing on the differentiation between subtypes of malignancy.

Modified Cyclodextrin Sulphates(mCDS11) have Potent Inhibitory Activity against HIV and High Oral Bioavailability

Modified cyclodextrin sulphate (mCDS) in which lipophilic groups were introduced to cyclodextrin sulphate (CDS) was synthesized and proved more inhibitory to the replication of HIV-1 and HIV-2 than CDS or dextran sulphate (DS). The anti-coagulant activity of mCDS was lower than that of DS. Cyclodextrin phosphate (CDP) showed anti-HIV activity similar to that of CDS, and its anti-coagulant activity was even lower than that of mCDS. Flow cytometric analysis suggested that the mechanism of the anti-HIV-1 action of CDS, mCDS, and CDP is based on inhibition of HIV-1 binding to the cells. The peak blood concentration after oral administration of mCDS11(potassium tris[6-benzylthio-6-deoxy]-β-cyclodextrin hexadecasulphate) to rabbits was about 1000 times higher than the concentration showing anti-HIV activity. The retention time in the blood was also long (blood half-life: 4 h). These results point to the potential usefulness of oral mCDS administration in the prophylaxis and/or therapy of HIV infections.

Inhibitory Effects of Polycations on the Replication of Enveloped Viruses (HIV, HSV, CMV, RSV, Influenza A Virus and Togaviruses) in vitro

Polycationic compounds, i.e. poly-l-lysines and poly-d-lysines, were evaluated for their in vitro effect on the replication of various viruses. Poly-l-lysines of different molecular weight proved inhibitory to the replication of several enveloped viruses, such as human immunodeficiency virus type 1 and type 2 (HIV-1 and HIV-2), respiratory syncytial virus (RSV), influenza A virus, Sindbis virus, Semliki Forest virus, vesicular stomatitis virus (VSV), herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (CMV). The mechanism of action of the polylysines against HIV-1, RSV and CMV could be attributed to an inhibitory effect on virus binding to the host cells, as demonstrated by an indirect immunofluorescence/laser flow cytofluorographic method, virus plaque reduction and measurement of radiolabelled virion association with the cells, respectively.

Sulphated Polymers are Potent and Selective Inhibitors of Various Enveloped Viruses, Including Herpes Simplex Virus, Cytomegalovirus, Vesicular Stomatitis Virus, Respiratory Syncytial Virus, and Toga-, Arena- and Retroviruses

The sulphated polymers, such as polyvinylalcohol sulphate (PVAS) and its co-polymer with acrylic acid (PAVAS), have proved to be potent inhibitors for herpes simplex virus, human cytomegalovirus, vesicular stomatitis virus, respiratory syncytial virus, Sindbis virus, Semliki Forest virus, Junin virus, Tacaribe virus, murine sarcoma virus and human immunodeficiency virus. They are not inhibitory to non-enveloped viruses, such as poliovirus and reovirus. The broad-spectrum antiviral effects of these compounds depend on their molecular weight and degree of sulphation. Pharmacokinetic studies in rabbits have indicated that after intravenous bolus injection the serum concentrations of these compounds decay biphasically, with an initial half-life of approximately 90–120 min.

Antiviral Activity of low-MW Dextran Sulphate (Derived from dextran MW 1000) Compared to Dextran Sulphate Samples of Higher MW

Dextran sulphate inhibits the replication of enveloped viruses (such as retro-, herpes-, toga, arena-, rhabdo-, orthomyxo- and paramyxoviruses), but is inactive against non-enveloped viruses (such as polio, Coxsackie and reovirus). Within the molecular weight (MW) range of 10000–50000, not much variation was observed in the antiviral potencies of different dextran sulphate (DS) samples, irrespective of the virus examined. However, in contrast with the higher MW samples, the low MW DS sample (prepared from dextran with a MW of 1000) was virtually inactive against herpes simplex virus type 1 and type 2, vesicular stomatitis virus, vaccinia virus, influenza A virus, respiratory syncytial virus and togaviruses (Sindbis, Semliki Forest). It was 10–20-fold less active than the higher MW samples against cytomegalovirus and arenaviruses (Junin, Tacaribe). The inhibitory potency of the 1000 MW DS sample against human immunodeficiency virus (HIV) varied considerably depending on the virus strain and cell type. When examined in MT-4 cells, the 1000 MW DS sample was 7000-, 1000-, 200- or 10-fold more inhibitory to HIV-1HE than HIV-2EHO, HTLV-IIIB, HTLV-IIIRF and LAV-2ROD, respectively. In CEM cells, however, HIV-1HE was less sensitive to the inhibitory effect of the 1000 MW DS sample than HIV-2EHO, equally sensitive as HTLV-IIIB and fivefold more sensitive than LAV-2ROD.

New Polyacetal Polysulphate Active against Human Immunodeficiency Virus and other Enveloped Viruses

A new polyacetal polysulphate, termed PAPS, was synthesized starting from dextran through oxidation, reduction, and subsequent sulphation. PAPS inhibited HIV-1- and HIV-2-induced cytopathicity in MT-4 cells at concentrations comparable to those required for dextran sulphate (MW5000) to inhibit the cytopathicity of these viruses (50% inhibitory concentration: 0.4–0.04 μg ml−1). At these concentrations PAPS had no anticoagulant activity. PAPS suppressed syncytium formation between MOLT-4 cells and persistently HIV-1- or HIV-2-infected HUT-78 cells at a concentration of 1 μg ml−1, that is 25- to 30-fold lower than that required for dextran sulphate to inhibit syncytium formation. Like dextran sulphate, PAPS inhibited HIV-1 binding to the cells and anti-gp120 mAb binding to HIV-1 gp120. Also, PAPS proved equally active as dextran sulphate against herpes simplex virus, cytomegalovirus and the arenaviruses Junin and Tacaribe, and 10-fold more active than dextran sulphate against vaccinia, Sindbis, influenza A, and vesicular stomatitis virus. Neither PAPS nor dextran sulphate proved inhibitory to the non-enveloped viruses polio, Coxsackie and reovirus. Pharmacokinetic studies in rabbits revealed that after intravenous bolus injection the serum concentrations of PAPS decayed biphasically, with an initial half-life of approximately 45–60 min. Twenty-four hours following their intraperitoneal administration to mice, PAPS as well as dextran sulphate generated low titres of an antiviral principle that was at least partially interferon-like.

Mechanism of the Antiviral Activity of New Aurintricarboxylic Acid Analogues

Various new aurintricarboxylic acid (ATA) polymer analogues have been evaluated for their antiviral activity against a wide array of DNA and RNA viruses, and their mechanism of action against human cytomegalovirus (HCMV) and human immunodeficiency virus type 1 (HIV-1). Most of the polymers exhibited marked antiviral activity against a variety of enveloped viruses, but not against non-enveloped viruses. The ATA polymers displayed the most pronounced activity against HIV-1, HCMV and human herpesvirus type 6 (HHV-6). Their action against HCMV and HIV could be ascribed to inhibition of the initial attachment of virus particles to the cells. Using radiolabelled virus, we proved that the polymers inhibit the binding of HCMV to HEL fibroblasts. By flow cytometric analysis, we demonstrated that these new polymers interfere with (i) the binding of OKT4A monoclonal antibody (mAb) to the cellular CD4 receptor, (ii) the binding of anti-gp120 mAb to HIV-1 glycoprotein (gp) 120, and (iii) the adsorption of HIV-1 virions and recombinant HIV-1gp120 (rgp120) to MT-4 cells. The presence of a salicylic acid substituent on the central bridging carbon in the parent compound ATA seems to play an important role in the anti-HIV activity of these ATA related polymer analogues.

Sulphated Cyclodextrins are Potent anti-HIV Agents Acting Synergistically with 2′,3′-dideoxynucleoside Analogues

Sulphated cyclodextrins proved to be potent inhibitors of human immunodeficiency virus (HIV), cytomegalovirus (CMV) and herpes simplex virus (HSV) but not other enveloped viruses (i.e. Sindbis virus, respiratory syncytial virus, Tacaribe virus, vesicular stomatitis virus or vaccinia virus). Their mechanism of action against HIV can be attributed to an inhibition of the binding of HIV-1 virions to the cells, as demonstrated by flow cytometric analysis. The sulphated cyclodextrins enhanced the anti-HIV-1 activity of pyrimidine 2′,3′-dideoxyribosides (i.e. azidothymidine, dideoxycytidine, didehydro-dideoxythymidine, fluorodide-oxychlorouridine), in a subsynergistic manner, and the anti-HIV-1 activity of purine 2′,3′-dideoxyribosides (dideoxyadenosine, dideoxyinosine, 2,6-diaminopurine dideoxyriboside) and 9-(2-phosphonylmethoxyethyl)adenine in a synergistic manner. Following intravenous administration of the sulphated cyclodextrins to rabbits, drug serum concentrations were obtained that were 100- to 1000-fold above the minimum inhibitory concentration for HIV or CMV.

Inhibition of HIV-1-Induced Cytopathogenicity, Syncytium Formation, and Virus-Cell Binding by Naphthalenedisulphonic Acids through Interaction with the Viral Envelope gp120 Glycoprotein

Bis-naphthalenedisulphonic acid derivatives with a biphenyl spacer, 4,4′-[4,4′-biphenyldiylbis(sulphonyl-amino)]bis(5-hydroxy-2,7-naphthalenedisulphonic acid) and 3,3′-[4,4′-biphenyldiylbis(sulphonyl-amino)]bis(1,5-naphthalenedisulphonic acid), have previously been reported as potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in cell culture. These compounds have also proved inhibitory to syncytium formation in cocultures of MOLT-4 cells with HIV-1-infected HUT-78 cells. They also inhibit the binding of HIV-1 virions to MT-4 cells as determined by a flow cytometric (FACS) method. Further studies on their mechanism of action by the FACS have revealed that the compounds inhibit the binding of anti-gp120 monoclonal antibody to the viral envelope glycoprotein gp120. Binding of OKT4A/Leu3a monoclonal antibody to the cellular CD4 receptor is not affected by the compounds. These results suggest that the anti-HIV-1 activity of the naphthalenedisulphonic acid derivatives can be attributed to inhibition of the gp120-CD4 interaction through binding of the compounds to the viral gp120 antigen.

Anti-HIV Activities of Anionic Metalloporphyrins and Related Compounds

Various water-soluble polysulphonated and polycarboxylated porphyrins and some of their metallated derivatives have been prepared and their antiviral properties against human immunodeficiency virus (HIV-1, HIV-2), simian immunodeficiency virus and other viruses are reported. Besides these polyanionic compounds, two new series of porphyrins were included and studied from the perspective of bio-availability modulation: (i) acefylsulphonamido derivatives endowed with weak acidity properties (deprotonation gives the corresponding anionic derivatives in a pH range 4.5-8.5) and (ii) compounds with the anionic charge transiently masked by esterification (acetoxymethyl- and pivaloyloxymethylesters). Among the more active compounds in inhibiting HIV-induced cytopathic effects, the sulphonated and carboxylated porphyrin complexes were found to interact directly with the HIV protein gp 120 and not with the CD4 cellular receptor.

Differential Activity of Polyanionic Compounds and Castanospermine against HIV Replication and HIV-Induced Syncytium Formation Depending on Virus Strain and Cell Type

Polyanionic compounds [i.e. pentosan polysulphate, dextran sulphate, heparin, suramin, and aurintricarboxylic acid (ATA)] and castanospermine were examined for their inhibitory effect on human immunodeficiency virus (HIV) strains (HIV-1IIIB, HIV-1RF, HIV-2ROD and HIV-2EHO) in two different assays (HIV cytopathicity in MT-4 cells and HIV antigen expression in CEM cells). In the MT-4 assay dextran sulphate and pentosan polysulphate were more active against HIV-2ROD, suramin was more active against HIV-1RF, and ATA more active against HIV-2EHO-Heparin was less, but castanospermine was more, active against the two HIV-2 strains. In the CEM assay dextran sulphate and suramin were equally active against all HIV strains, pentosan polysulphate was more active against both HIV-2 strains, whereas heparin was less active against HIV-2ROD and ATA again was more active against HIV-2EHO. The compounds and soluble CD4 (sCD4) were also tested in the HIV-induced syncytium formation assay, where chronically infected HUT-78 cells were mixed with uninfected MOLT-4 or CEM cells. The inhibitory effect of suramin and ATA on syncytium formation was independent of the virus strain or cell type. For dextran sulphate and pentosan polysulphate, it was dependent on virus strain, and for heparin, castanospermine, and sCD4, it was dependent on both the virus strain and cell type.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+)  cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1β, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1β/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

CXCL12-CXCR4 axis in angiogenesis, metastasis and stem cell mobilization

Chemokines are key players in the attraction and activation of leukocytes and are thus implicated in the recruitment of immune cells at sites of infection and/or inflammation. They exert their action by binding to seven-transmembrane G protein-coupled receptors. The chemokine stromal cell-derived factor-1 (SDF-1)/CXCL12 represents the single natural ligand for the chemokine receptor CXCR4. CXCL12 possesses angiogenic properties and is involved in the outgrowth and metastasis of CXCR4-expressing tumors and in certain inflammatory autoimmune disorders, such as rheumatoid arthritis. CXCR4 expression on tumor cells is upregulated by hypoxia and angiogenic factors, such as vascular endothelial growth factor (VEGF). CXCR4 also acts as a co-receptor for entry of human immunodeficiency virus (HIV) in CD4(+) T cells. Finally, CXCL12/CXCR4 interactions were shown to play an important role in the migration of hematopoietic stem cells and their progenitors from, and their retention within, the bone marrow, a site characterized by high CXCL12 expression. As such, CXCR4 inhibitors may be utilized to inhibit HIV-1 infection, tumor growth and metastasis and to mobilize hematopoietic stem cells from the bone marrow in the circulation, where they can be collected for autologous stem cell transplantation. Here, we discuss the different aspects of CXCL12/CXCR4 biology as well as the development and anti-cancer/stem cell mobilizing activity of CXCR4 antagonists.

Diffusion of Two Potential Anti-HIV Microbicides across Intact and De-Epithelialised, Human Vaginal Mucosa

The lectins derived from Hippeastrum hybrid ( Hippeastrum hybrid agglutinin, HHA) and from the stinging nettle Urtica dioica (UDA) have been investigated as anti-HIV microbicides. The present study was conducted to determine their diffusion through intact and de-epithelialised human vaginal epithelium. Both lectins were labelled with fluorescein isothiocyanate groups (FITC) and analysed by SDS-polyacrylamide gel electrophoresis. While UDA appeared to be fairly homogeneous with an average Mw of ∼ 8.5 kDa, HHA was a heterogeneous mixture of compounds with Mw's ranging between ∼ 13 and 52 kDa. Fresh human vaginal mucosa was snap-frozen in liquid nitrogen and stored at −85°C. Prior to an experiment, the tissue was defrosted to 20°C in PBS buffer, pH 7.4, and placed in the seven flow cells of a flow-through perfusion apparatus. Either FITC-labelled HHA or UDA was then pipetted into the donor chamber of the flow cell. Samples from each flow cell were collected every 2 hours (1.5 ml/h) over a 24-hour period and analysed by fluorospectrophotometry. Permeability experiments were repeated with vaginal mucosa specimens from which the epithelial layers had been removed by heat-stripping. Both lectins diffused through vaginal mucosa at rates proportionate to their average molecular weights, the flux rates of the smaller UDA being ∼ 5x higher than that of the larger HHA. Removal of the vaginal epithelium increased the flux rates of both HHA and UDA across the mucosa and this may have implications for a more rapid in vivo uptake of these lectins when used as anti-HIV microbicides.

Carbohydrate-binding agents (CBAs) inhibit HIV-1 infection in human primary monocyte-derived macrophages (MDMs) and efficiently prevent MDM-directed viral capture and subsequent transmission to CD4+ T lymphocytes

Carbohydrate-binding agents (CBAs) have been proposed as innovative anti-HIV compounds selectively targeting the glycans of the HIV-1 envelope glycoprotein gp120 and preventing DC-SIGN-directed HIV capture by dendritic cells (DCs) and transmission to CD4(+) T-lymphocytes. We now show that CBAs efficiently prevent R5 HIV-1 infection of human primary monocyte-derived macrophage (MDM) cell cultures in the nanomolar range. Both R5 and X4 HIV-1 strains were efficiently captured by the macrophage mannose-binding receptor (MMR) present on MDM. HIV-1 capture by MMR-expressing MDM was inhibited by soluble mannose-binding lectin and MMR antibody. Short pre-exposure of these HIV-1 strains to CBAs is able to prevent virus capture by MDM and subsequent syncytia formation in cocultures of the CBA-exposed HIV-1-captured MDM and uninfected CD4(+) T-lymphocytes. The potential of CBAs to impair MDM in their capacity to capture and to transmit HIV to T-lymphocytes might be an important property to be taken into consideration in the eventual choice to select microbicide candidate drugs for clinical investigation.

Restricted entry of R5 HIV Type 1 strains into eosinophilic cells

A cell culture system previously developed by our laboratory demonstrated that T cell-tropic (CXCR4-using) but not macrophage-tropic (CCR5-using) HIV-1 strains productively infected eosinophilic cells. In the current study, an improved model was used to determine the level of this viral restriction by assessing viral entry and coreceptor usage. The model was improved by using AML14.3D10 cells that were engineered to express CCR3 in addition to the major HIV-1 coreceptors, CD4, CXCR4, and CCR5, thus making them more like primary eosinophils. A polymerase chain reaction (PCR) assay was used to detect viral entry. In the PCR assay, primers specific for early reverse transcription products were used to amplify minus strand viral DNA from HIV-1-infected AML14.3D10-CCR3 eosinophilic cells. Coreceptor blocking experiments, using the CXCR4 antagonist AMD3100, were performed to determine coreceptor usage by the CXCR4-using (X4) strain known to productively infect the cells. Virus production was measured by p24 immunoassay. As expected, viral DNA was detected in AML14.3D10-CCR3 cells infected with X4 HIV-1, and cell viability was decreased during maximal viral production. Conversely, viral DNA was not detected in eosinophilic cells exposed to a CCR5-using (R5) HIV-1 strain that is also capable of using CCR3, indicating that R5 HIV-1 is unable to enter eosinophilic cells despite the presence of the appropriate coreceptors. Infection of AML14.3D10-CCR3 cells by HTLV-III(B) was completely inhibited by AMD3100, indicating that X4 HIV-1 enters the AML14.3D10-CCR3 cell line by using the CXCR4 coreceptor exclusively. Since X4 strains predominate during the late stages of HIV-1 infection in many patients, when eosinophil numbers also tend to increase, the ability of these HIV-1 strains to infect eosinophilic cells has important implications for the involvement of eosinophils in the pathogenesis of AIDS.

[Role of chemokines in the HIV infection process]

In order to infect a target cell, the HIV envelope glycoprotein gp 120 has to interact with both the cellular receptor CD4 and an HIV-coreceptor, i.e. the CC or CXC chemokine receptor CCR5 or CXCR4. Both coreceptors were immediately recognized as novel targets for anti-HIV-therapy. Blocking these coreceptors would protect the cell from viral entry and would reduce the viral transmission and pathogenesis. Here we describe the purification and characterization of natural chemokine variants and compare their antiviral activity. In addition, the role of proteases for the processing of the CC chemokines RANTES, eotaxin, MDC and MIP-1 alpha and of the CXC chemokine SDF-1 are studied. The MIP-1 alpha-isoform LD78 beta, that was purified form natural sources, inhibited HIV-infection completely in CCR5-transfected cells, mononuclear leukocytes and purified monocytes at low (ng/ml) concentrations. This research will make it feasible to develop specific chemokine-analogs that block HIV-entry. Deciphering the processes that play a role during the complicated interactions between HIV-gp120 and the cellular membrane may lead to a more efficient treatment of HIV-infections.

X4 HIV-1 induces neuroblastoma cell death by interference with CXCL12/CXCR4 interaction

Human neuroblastoma SK-N-SH cells strongly express CXC-chemokine receptor 4 (CXCR4), the principal coreceptor for X4 HIV-1 strains, and its natural ligand stromal cell-derived factor 1 (SDF-1, recently renamed CXCL12). We investigated the impact of CXCR4 blockade by the specific CXCR4 antagonist AMD3100 or by X4 HIV-1 virus particles on the growth and survival of neuroblastoma SK-N-SH cells. SK-N-SH cell proliferation was inhibited byAMD3100 and anti-CXCL12 neutralizing antibodies, but enhanced by exogenously added CXCL12. Upon prolongedexposure to AMD3100, SK-N-SH cell death occurred throughdeficit of survival-promoting and growth-stimulatory signals generated by endogenous CXCL12. In analogy with the observations made with the CXCR4 inhibitor AMD3100, the X4 HIV-1 strains IIIB and SF-2, but not the R5 strain BaL, caused a marked cytopathic effect and strongly effected SK-N-SH cell death after at least 10 days of incubation. However, no virus production could be detected in the HIV-1-inoculated SK-N-SH cell cultures. Exogenously added CXCL12 afforded partial protection against X4 HIV-1-induced cytopathicity in SK-N-SH cells. Our data indicate that the endogenous CXCL12/CXCR4 signaling axis is critical for neuroblastoma cell survival and proliferation. Long-term blockade of CXCR4 through physical contact with the X4 HIV-1 envelope can cause neuronal cell death. This mechanism may possibly play a role in X4 HIV-associated neurodegeneration.

Induction of apoptosis by cidofovir in human papillomavirus (HPV)-positive cells

HPMPC (cidofovir, CDV) is an acyclic nucleoside phosphonate (ANP) with broad-spectrum activity against DNA viruses, including human papillomavirus (HPV). HPMPC has proved to be effective in the treatment of HPV-associated disease in several clinical investigations. In vitro, treatment of HPV-positive cells (compared with normal primary human keratinocytes) with HPMPC has resulted in a concentration- and time-dependent inhibition of cell proliferation. We have now evaluated the mechanism by which this compound induces cell death. Different parameters of apoptosis, that is, (i) induction of CPP32 (caspase-3) protease activity, (ii) translocation of phosphatidylserine (PS) from the inner part of the plasma membrane to the outer layer, (iii) disintegration of the nuclear matrix protein (NMP), (iv) DNA fragmentation, (v) number of cells in apoptotic phase following cell cycle analysis, showed that the mechanism of cell death following treatment with CDV is based on apoptosis. Annexin V staining showed that induction of apoptosis in HPV-positive cells was correlated with a decrease in the percentage of viable cells, while no significant changes in the percentages of living cells were noted in primary human keratinocytes (PHK) cell cultures. Furthermore, a remarkable accumulation of HPMPC-treated cells in the S phase of the cell cycle was observed. Apoptosis induction and S phase arrest were concentration and time dependent. Induction of apoptosis in HPV-positive cells by HPMPC was associated with accumulation of the tumor suppressor protein p53 and the cyclin-dependent kinase inhibitor p21/WAF-1. As HPMPC has proved to induce apoptosis, in a time- and concentration-dependent manner, in a number of HPV-positive cell lines, the regression of papillomatous lesions observed with HPMPC in patients may be due, at least in part, to the induction of apoptosis.

Inhibition of HIV infection by CXCR4 and CCR5 chemokine receptor antagonists

The chemokine receptors CXCR4 and CCR5 are used as co-receptors by the T cell-tropic (X4) and macrophage-tropic (R5) HIV-1 strains, respectively, for entering their host cells. Viral entry can be inhibited by the natural ligands for CXCR4, the CXC chemokine SDF-1 and CCR5, the CC chemokines RANTES, MIP-1alpha and MIP-1beta. Several peptidic compounds, T22 (an 18-mer), T134 (a 14-mer), ALX40-4C (a 9-mer) and CGP 64222 (also a 9-mer), have been identified as CXCR4 antagonists and show anti-HIV activity. Also, the HIV-1 tat protein has been described as a 'natural' CXCR4 antagonist with anti-HIV-1 activity. The most potent and specific CXCR4 antagonists are the bicyclam derivatives, which also potently block X4 HIV replication. AMD3100 has proved to be a highly specific CXCR4 antagonist, which consistently blocks the outgrowth of all X4 HIV and dual-tropic (R5/X4) variants that use CXCR4 for entering the cells (cell lines, CXCR4-transfected cell lines, lymphocytes or monocytes/ macrophages). From the bicyclam analogues, AMD3100 was selected as the clinical drug candidate, which, after initial Phase I (safety) studies, has proceeded to Phase II (efficacy) trials. The first non-peptidic compound that interacts with CCR5, and not with CXCR4, is a quaternary ammonium derivative, called TAK-779, which also has potent but variable anti-HIV activity. We believe that HIV entry/fusion inhibitors will become important new antiviral agents to combat AIDS. However, like the current clinically approved agents, they will need to be used in combinations consisting of antivirals that target other aspects of the HIV replication cycle, such as reverse transcriptase and protease, to obtain optimum therapeutic effects.

Quantitative evaluation of HIV-1 coreceptor use in the GHOST3 cell assay

The utility of the GHOST(3) cell assay has been evaluated for testing coreceptor use of primary human immunodeficiency virus type 1 (HIV-1) isolates. GHOST(3) cells were derived from the human osteosarcoma cell line, HOS, and have been engineered to stably express CD4 and one or another of the chemokine receptors CCR3, CCR5, CXCR4, Bonzo, or the orphan receptor BOB. The indicator cell line carries the HIV-2 long terminal repeat-driven green fluorescence protein (GFP) gene, which becomes activated upon infection with HIV or simian immunodeficiency virus. Viral entry is followed by Tat activation of transcription and GFP becomes expressed. Infected cells can be detected 2 or 3 days after infection by simple fluorescence microscopic observation. This simplicity is the main advantage of the GHOST(3) cell system and makes it particularly suitable for screening of a large number of isolates. In addition, the efficiency of coreceptor use can be accurately quantitated with flow cytometric analysis. Here, we evaluated the coreceptor use of 59 primary HIV-1 isolates of different subtypes.

Coreceptor usage of sequential isolates from cynomolgus monkeys experimentally Infected with simian immunodeficiency virus (SIVsm)

Sequential isolates from eight cynomolgus monkeys experimentally infected with simian immunodeficiency virus (SIVsm, of sooty mangabey origin) were tested for coreceptor use in the human osteosarcoma indicator cell line, GHOST(3), expressing CD4 and one or another of the chemokine receptors CCR3, CCR5, CXCR4, BOB, or the orphan receptor Bonzo. The indicator cell line carries the human immunodeficiency virus type 2 long terminal repeat-driven green fluorescence protein gene that becomes activated upon infection with HIV or SIV and fluorescence can be quantitated by flow cytometric analysis. The methodological details are described in the accompanying paper (Vödrös et al., 2001, Virology 290, in press). All SIVsm inoculum viruses and reisolates used CCR5 with a high level of efficiency. CCR5 use was stable over time. BOB and Bonzo use was less efficient than CCR5 use and, in particular, late isolates obtained at the time of immunodeficiency varied greatly in their coreceptor use and often could not establish a productive infection in BOB- or Bonzo-expressing cells. Unexpectedly, early reisolates obtained 12 days postinfection could infect the entire GHOST(3) panel including the parental cells. In one case this was due to use of CXCR4, either transfected or endogenously expressed on the GHOST(3) cells. Our results demonstrate the complex coreceptor use of SIVsm isolates. Moreover, they focus attention on the initial phase of virus replication when the availability of target cells may govern the replication pattern of the virus.

HIV-1 gp120 and chemokine activation of Pyk2 and mitogen-activated protein kinases in primary macrophages mediated by calcium-dependent, pertussis toxin-insensitive chemokine receptor signaling

Human immunodeficiency virus type 1 (HIV-1) uses the chemokine receptors CCR5 and CXCR4 as coreceptors for entry. It was recently demonstrated that HIV-1 glycoprotein 120 (gp120) elevated calcium and activated several ionic signaling responses in primary human macrophages, which are important targets for HIV-1 in vivo. This study shows that chemokine receptor engagement by both CCR5-dependent (R5) and CXCR4-dependent (X4) gp120 led to rapid phosphorylation of the focal adhesion-related tyrosine kinase Pyk2 in macrophages. Pyk2 phosphorylation was also induced by macrophage inflammatory protein-1beta (MIP-1beta) and stromal cell-derived factor-1alpha, chemokine ligands for CCR5 and CXCR4. Activation was blocked by EGTA and by a potent blocker of calcium release-activated Ca++ (CRAC) channels, but was insensitive to pertussis toxin (PTX), implicating CRAC-mediated extracellular Ca++ influx but not Galpha(i) protein-dependent mechanisms. Coreceptor engagement by gp120 and chemokines also activated 2 members of the mitogen-activated protein kinase (MAPK) superfamily, c-Jun amino-terminal kinase/stress-activated protein kinase and p38 MAPK. Furthermore, gp120-stimulated macrophages secreted the chemokines monocyte chemotactic protein-1 and MIP-1beta in a manner that was dependent on MAPK activation. Thus, the gp120 signaling cascade in macrophages includes coreceptor binding, PTX-insensitive signal transduction, ionic signaling including Ca++ influx, and activation of Pyk2 and MAPK pathways, and leads to secretion of inflammatory mediators. HIV-1 Env signaling through these pathways may contribute to dysregulation of uninfected macrophage functions, new target cell recruitment, or modulation of macrophage infection.

Macrophage tropism of human immunodeficiency virus type 1 isolates from brain and lymphoid tissues predicts neurotropism independent of coreceptor specificity

The viral determinants that underlie human immunodeficiency virus type 1 (HIV-1) neurotropism are unknown, due in part to limited studies on viruses isolated from brain. Previous studies suggest that brain-derived viruses are macrophage tropic (M-tropic) and principally use CCR5 for virus entry. To better understand HIV-1 neurotropism, we isolated primary viruses from autopsy brain, cerebral spinal fluid, blood, spleen, and lymph node samples from AIDS patients with dementia and HIV-1 encephalitis. Isolates were characterized to determine coreceptor usage and replication capacity in peripheral blood mononuclear cells (PBMC), monocyte-derived macrophages (MDM), and microglia. Env V1/V2 and V3 heteroduplex tracking assay and sequence analyses were performed to characterize distinct variants in viral quasispecies. Viruses isolated from brain, which consisted of variants that were distinct from those in lymphoid tissues, used CCR5 (R5), CXCR4 (X4), or both coreceptors (R5X4). Minor usage of CCR2b, CCR3, CCR8, and Apj was also observed. Primary brain and lymphoid isolates that replicated to high levels in MDM showed a similar capacity to replicate in microglia. Six of 11 R5 isolates that replicated efficiently in PBMC could not replicate in MDM or microglia due to a block in virus entry. CD4 overexpression in microglia transduced with retroviral vectors had no effect on the restricted replication of these virus strains. Furthermore, infection of transfected cells expressing different amounts of CD4 or CCR5 with M-tropic and non-M-tropic R5 isolates revealed a similar dependence on CD4 and CCR5 levels for entry, suggesting that the entry block was not due to low levels of either receptor. Studies using TAK-779 and AMD3100 showed that two highly M-tropic isolates entered microglia primarily via CXCR4. These results suggest that HIV-1 tropism for macrophages and microglia is restricted at the entry level by a mechanism independent of coreceptor specificity. These findings provide evidence that M-tropism rather than CCR5 usage predicts HIV-1 neurotropism.

Antiviral agents active against human herpesviruses HHV-6, HHV-7 and HHV-8

A series of antiviral compounds were examined for their activity against human herpesvirus type 6 (HHV-6), type 7 (HHV-7) and type 8 (HHV-8). They were selected either because they are already approved for clinical use in the treatment of herpesvirus infections (acyclovir, valaciclovir, penciclovir, famciclovir, ganciclovir, brivudin, foscarnet and cidofovir) or have demonstrated marked activity against herpesviruses (lobucavir, H2G, A-5021, D/L-cyclohexenyl G and S2242). In view of their host cell specificity, different cells and assays had to be used for determining antiviral activity against these three viruses. The most potent compounds with the highest antiviral selectivity index were: (i) for HHV-6; foscarnet, S2242, A-5021 and cidofovir; (ii) for HHV-7; S2242, cidofovir and foscarnet; and (iii) for HHV-8; S2242, cidofovir and ganciclovir. As mycophenolic acid has been shown to enhance significantly the activity of acyclic guanosine analogues (such as acyclovir, penciclovir and ganciclovir) in vitro against HSV-1, HSV-2, VZV and HCMV, it would seem worth evaluating whether mycophenolic acid also potentiates the activity of these acyclic guanosine analogues against HHV-6, -7 and -8.

Productive infection of primary macrophages with human herpesvirus 7

Here we demonstrate replication of human herpesvirus 7 (HHV-7), a T-lymphotropic virus, in macrophages. Productive replication was lost after 2 weeks, but HHV-7 DNA was detected up to 1 month after infection. Thus, macrophages become infected by HHV-7 and might play an important role as a viral reservoir, as has been demonstrated for human immunodeficiency virus type 1.

AMD3100, a potent and specific antagonist of the stromal cell-derived factor-1 chemokine receptor CXCR4, inhibits autoimmune joint inflammation in IFN-gamma receptor-deficient mice

Autoimmune collagen-induced arthritis (CIA) in IFN-gammaR-deficient DBA/1 mice was shown to be reduced in severity by treatment with the bicyclam derivative AMD3100, a specific antagonist of the interaction between the chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4. The beneficial effect of the CXCR4 antagonist was demonstrable when treatment was initiated between the time of immunization and appearance of the first symptoms. Treatment also reduced the delayed-type hypersensitivity response to the autoantigen, collagen type II. These observations are indicative of an action on a late event in the pathogenesis, such as chemokine-mediated attraction of leukocytes toward joint tissues. The notion of SDF-1 involvement was further supported by the observation that exogenous SDF-1 injected in periarthritic tissue elicited an inflammatory response that could be inhibited by AMD3100. The majority of leukocytes harvested from inflamed joints of mice with CIA were found to be Mac-1(+) and CXCR4(+), and AMD3100 was demonstrated to interfere specifically with chemotaxis and Ca(2+) mobilization induced in vitro by SDF-1 on Mac-1(+)/CXCR4(+) splenocytes. We conclude that SDF-1 plays a central role in the pathogenesis of murine CIA, by attracting Mac-1(+)/CXCR4(+) cells to the inflamed joints.

CXCR4 is the primary receptor for feline immunodeficiency virus in astrocytes

Feline astrocytes were productively infected with the Crandell feline kidney (CrFK) cell-adapted feline immunodeficiency virus (FIV) Petaluma strain in a primary culture. They expressed mRNA of CXCR4, and the FIV infection was blocked by stromal cell-derived factor 1alpha (SDF-1alpha), SDF-1beta, or the bicyclam AMD3100 in a dose-dependent manner. These observations suggest that, like FIV infection in CrFK cells and lymphocytes, the virus uses CXCR4 as a primary receptor for infecting astrocytes and this can be a possible natural model for AIDS dementia complex.

No selection for CCR5 coreceptor usage during parenteral transmission of macrophagetropic syncytium-inducing human immunodeficiency virus type 1

In two cases of parenteral transmission of human immunodeficiency virus type 1 (HIV-1) syncitium-inducing (SI) variants, we previously observed selection for macrophagetropic variants. Although infection of macrophages is generally mediated via CCR5, we found no selection for SI variants that could use CCR5 as coreceptor in addition to CXCR4, suggesting that features other than coreceptor usage account for the macrophagetropism of these transmitted SI HIV-1 variants.

CXCR4-activated astrocyte glutamate release via TNFalpha: amplification by microglia triggers neurotoxicity

Astrocytes actively participate in synaptic integration by releasing transmitter (glutamate) via a calcium-regulated, exocytosis-like process. Here we show that this process follows activation of the receptor CXCR4 by the chemokine stromal cell-derived factor 1 (SDF-1). An extraordinary feature of the ensuing signaling cascade is the rapid extracellular release of tumor necrosis factor-alpha (TNFalpha). Autocrine/paracrine TNFalpha-dependent signaling leading to prostaglandin (PG) formation not only controls glutamate release and astrocyte communication, but also causes their derangement when activated microglia cooperate to dramatically enhance release of the cytokine in response to CXCR4 stimulation. We demonstrate that altered glial communication has direct neuropathological consequences and that agents interfering with CXCR4-dependent astrocyte-microglia signaling prevent neuronal apoptosis induced by the HIV-1 coat glycoprotein, gp120IIIB. Our results identify a new pathway for glia-glia and glia-neuron communication that is relevant to both normal brain function and neurodegenerative diseases.

Diverging binding capacities of natural LD78beta isoforms of macrophage inflammatory protein-1alpha to the CC chemokine receptors 1, 3 and 5 affect their anti-HIV-1 activity and chemotactic potencies for neutrophils and eosinophils

Recently, the LD78beta isoform of the CC chemokine macrophage inflammatory protein (MIP)-1alpha was shown to efficiently chemoattract lymphocytes and monocytes and to inhibit infection of mononuclear cells by R5 HIV-1 strains. We have now demonstrated that after cleavage of the NH2-terminal Ala-Pro dipeptide by CD26, LD78beta(3 - 70) became the most potent chemokine blocking HIV-1. LD78beta(3 - 70) competed tenfold more efficiently than LD78beta(1 - 70) with [125I] RANTES for binding to the CC chemokine receptors CCR5 and CCR1. Contrary to LD78alpha, LD78beta(1 - 70) at 30 ng/ml efficiently competed with [125I] RANTES for binding to CCR3 and mobilized calcium in CCR3 transfectants, whereas LD78beta(3 - 70) showed a 30-fold decrease in CCR3 affinity compared to LD78beta(1 - 70). This demonstrates the importance of the penultimate proline in LD78beta(1 - 70) for CCR3 recognition. Both LD78beta isoforms efficiently chemoattracted eosinophils from responsive donors. In contrast, only the CCR3 agonist LD78beta(1 - 70) and not LD78beta(3 - 70), induced calcium increases in eosinophils with low levels of CCR1. In responder neutrophils, LD78beta(3 - 70) elicited calcium fluxes at a 30-fold lower dose (10 ng/ml) compared to intact LD78beta and LD78alpha, whereas the three MIP-1alpha isoforms were equipotent neutrophil chemoattractants. Taken together, both LD78beta isoforms are potent HIV-1 inhibitors (CCR5) and activators for neutrophils (CCR1) and eosinophils (CCR1, CCR3), affecting infection and inflammation.

Mutation of Asp(171) and Asp(262) of the chemokine receptor CXCR4 impairs its coreceptor function for human immunodeficiency virus-1 entry and abrogates the antagonistic activity of AMD3100

The bicyclam AMD3100 is a highly potent and selective CXCR4 antagonist with strong antiviral activity against human immunodeficiency virus (HIV)-1 and HIV-2, which use CXCR4 as coreceptor for host cell entry. Here, we investigated the interaction of AMD3100 with CXCR4 at the molecular level by mutational analysis. We established a set of stably transfected U87.CD4 cell lines expressing different mutant forms of CXCR4 (i.e., CXCR4[WT], CXCR4[D171N], CXCR4[D262N], CXCR4[D171N,D262N], and CXCR4[H281A]), to compare the activity of the compound against mutated versus wild-type CXCR4. We found that the antagonistic action of AMD3100 against CXCR4--as assessed by the inhibitory effects of the compound on stromal cell-derived factor (SDF-1) binding to its receptor and on SDF-1-induced intracellular calcium signaling, and by displacement of the CXCR4-specific antibody, clone 12G5--was greatly reduced by substitution of Asp(171) and/or Asp(262) by neutral asparagine residue(s). Both aspartates, but most particularly Asp(262), also proved essential for the anti-HIV-1 activity of AMD3100 against the viruses NL4.3, IIIB, and HE. In contrast, substitution of His(281) by a neutral alanine potentiated the antagonistic and antiviral effects of the compound in the different assay systems. Importantly, compared with the wild-type receptor, CXCR4[D262N] was much less effective, whereas CXCR4[D171N,D262N] completely failed as a coreceptor for infection by HIV-1 NL4.3. Thus, the negatively charged aspartate residues at positions 171 and 262, located in transmembrane domains 4 and 6 of the 7-transmembrane receptor, respectively, may represent crucial sites for electrostatic interaction of the positive charges of the bicyclams, as well as for the highly basic V3 loop of the gp120 envelope protein of certain HIV-1 strains.

The LD78beta isoform of MIP-1alpha is the most potent CC-chemokine in inhibiting CCR5-dependent human immunodeficiency virus type 1 replication in human macrophages

The CC-chemokines RANTES, macrophage inflammatory protein 1alpha (MIP-1alpha), and MIP-1beta are natural ligands for the CC-chemokine receptor CCR5. MIP-1alpha, also known as LD78alpha, has an isoform, LD78beta, which was identified as the product of a nonallelic gene. The two isoforms differ in only 3 amino acids. LD78beta was recently reported to be a much more potent CCR5 agonist than LD78alpha and RANTES in inducing intracellular Ca2+ signaling and chemotaxis. CCR5 is expressed by human monocytes/macrophages (M/M) and represents an important coreceptor for macrophage-tropic, CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1) strains to infect the cells. We compared the antiviral activities of LD78beta and the other CC-chemokines in M/M. LD78beta at 100 ng/ml almost completely blocked HIV-1 replication, while at the same concentration LD78alpha had only weak antiviral activity. Moreover, when HIV-1 infection in M/M was monitored by a flow cytometric analysis using p24 antigen intracellular staining, LD78beta proved to be the most antivirally active of the chemokines. RANTES, once described as the most potent chemokine in inhibiting R5 HIV-1 infection, was found to be considerably less active than LD78beta. LD78beta strongly downregulated CCR5 expression in M/M, thereby explaining its potent antiviral activity.

Incidence of psychotic disorders in immigrant groups to The Netherlands

BACKGROUND

Previous reports on the incidence of schizophrenia in immigrant groups to The Netherlands were based on hospital data.

AIMS

To compare the incidence of psychotic disorders in the immigrant groups to that in natives.

METHOD

Two-year first-contact incidence study in The Hague.

RESULTS

The risks of schizophrenia, schizophreniform or schizoaffective disorder (DSM-IV criteria) were increased for subjects born in Morocco (gender and age-adjusted relative risk=4.5; 95% Cl 1.4-8.5), Surinam (relative risk=3.2; 1.8-5.7), The Netherlands Antilles (relative risk=2.9; 0.9-9.5) and other non-Western countries (relative risk=2.4; 1.3-4.7). This risk was also increased for Moroccans (relative risk=8.0; 2.6-24.5) and Surinamese (relative risk=5.5; 2.5-11.9) of the second generation. The risks for Turkish immigrants, first or second generation, and for immigrants from Western countries were not significantly increased.

CONCLUSIONS

This study indicates that the incidence of schizophrenia is increased in several, but not all, immigrant groups to The Netherlands. It is possible that factors associated with a process of rapid westernisation precipitate schizophrenia in people who are genetically at risk.

Acyclic/carbocyclic guanosine analogues as anti-herpesvirus agents

Several guanosine analogues, i.e. acyclovir (and its oral prodrug valaciclovir), penciclovir (in its oral prodrug form, famciclovir) and ganciclovir, are widely used for the treatment of herpesvirus [i.e. herpes simplex virus type 1 (HSV-1), and type 2 (HSV-2), varicella-zoster virus (VZV) and/or human cytomegalovirus (HCMV)] infections. In recent years, several new guanosine analogues have been developed, including the 3-membered cyclopropylmethyl and -methenyl derivatives (A-5021 and synguanol) and the 6-membered D- and L-cyclohexenyl derivatives. The activity of the acyclic/carbocyclic guanosine analogues has been determined against a wide spectrum of viruses, including the HSV-1, HSV-2, VZV, HCMV, and also human herpesviruses type 6 (HHV-6), type 7 (HHV-7) and type 8 (HHV-8), and hepatitis B virus (HBV). The new guanosine analogues (i.e. A-5021 and D- and L-cyclohexenyl G) were found to be particularly active against those viruses (HSV-1, HSV-2, VZV) that encode for a specific thymidine kinase (TK), suggesting that their antiviral activity (at least partially) depends on phosphorylation by the virus-induced TK. Marked antiviral activity was also noted with A-5021 against HHV-6 and with D- and L-cyclohexenyl G against HCMV and HBV. The antiviral activity of the acyclic/carbocyclic nucleoside analogues could be markedly potentiated by mycophenolic acid, a potent inhibitor of inosine 5'-monophosphate (IMP) dehydrogenase. The new carbocyclic guanosine analogues (i.e. A-5021 and D- and L-cyclohexenyl G) hold great promise, not only as antiviral agents for the treatment of herpesvirus infections, but also an antitumor agents for the combined gene therapy/chemotherapy of cancer, provided that (part of) the tumor cells have been transduced by the viral (HSV-1, VZV) TK gene.

Coreceptor choice and T cell depletion by R5, X4, and R5X4 HIV-1 variants in CCR5-deficient (CCR5delta32) and normal human lymphoid tissue

Coreceptor utilization by HIV-1 is an important determinant of pathogenesis. However, coreceptor selectivity is defined in vitro, while in vivo critical pathogenic events occur in lymphoid tissues. Using pharmacological inhibitors, we recently provided evidence that coreceptor selectivity by the R5X4 dual-tropic isolate 89.6 was more restricted in ex vivo infected lymphoid tissue than in vitro [S. Glushakova, Y. Yi, J. C. Grivel, A. Singh, D. Schols, E. De Clercq, R. G. Collman, and L. Margolis (1999). J. Clin. Invest. 104, R7-R11]. Here we extend those observations using CCR5-deficient (CCR5Delta32) lymphoid tissue as well as additional primary isolates. We definitively show that neither CCR5 nor secondary coreceptors used in vitro mediate 89.6 infection in lymphoid tissue. We also demonstrate that restricted coreceptor use in lymphoid tissue ex vivo compared with in vitro utilization occurs with other dual-tropic primary isolates and is not unique to 89.6. For all strains tested that are dual tropic in vitro, severe CD4 T cell depletion in lymphoid tissue correlated with preferential CXCR4 use in this ex vivo system.

Polyanionic (i.e., polysulfonate) dendrimers can inhibit the replication of human immunodeficiency virus by interfering with both virus adsorption and later steps (reverse transcriptase/integrase) in the virus replicative cycle

Polyanionic dendrimers were synthesized and evaluated for their antiviral effects. Phenyldicarboxylic acid (BRI6195) and naphthyldisulfonic acid (BRI2923) dendrimers were found to inhibit the replication of human immunodeficiency virus type 1 (HIV-1; strain III(B)) in MT-4 cells at a EC(50) of 0.1 and 0.3 microg/ml, respectively. The dendrimers were not toxic to MT-4 cells up to the highest concentrations tested (250 microg/ml). These compounds were also effective against various other HIV-1 strains, including clinical isolates, HIV-2 strains, simian immunodeficiency virus (SIV, strain MAC(251)), and HIV-1 strains that were resistant to reverse transcriptase inhibitors. HIV strains containing mutations in the envelope glycoprotein gp120 (engendering resistance to known adsorption inhibitors) displayed reduced sensitivity to the dendrimers. The compounds inhibited the binding of wild-type virus and recombinant virus (containing wild-type gp120) to MT-4 cells at concentrations comparable to those that inhibited the replication of HIV-1(III(B)) in these cells. Cellular uptake studies indicated that BRI2923, but not BRI6195, permeates into MT-4 and CEM cells. Accordingly, the naphtyldisulfonic acid dendrimer (BRI2923) proved able to inhibit later steps of the replication cycle of HIV, i.e., reverse transcriptase and integrase. NL4.3 strains resistant to BRI2923 were selected after passage of the virus in the presence of increasing concentrations of BRI2923. The virus mutants showed 15-fold reduced sensitivity to BRI2923 and cross-resistance to known adsorption inhibitors. However, these virus mutants were not cross-resistant to reverse transcriptase inhibitors or protease inhibitors. We identified several mutations in the envelope glycoprotein gp120 gene (i.e., V2, V3, and C3, V4, and C4 regions) of the BRI2923-resistant NL4.3 strains that were not present in the wild-type NL4.3 strain, whereas no mutations were found in the reverse transcriptase or integrase genes.

Viral entry as the primary target for the anti-HIV activity of chicoric acid and its tetra-acetyl esters

The antiviral activity of L-chicoric acid against HIV-1 has been attributed previously to the inhibition of HIV-1 integration. This conclusion was based on the inhibition of integrase activity in enzymatic assays and the isolation of a resistant HIV strain with a mutation (G140S) in the integrase gene. Here we show that the primary antiviral target of L-CA and its analogs in cell culture is viral entry. L- and D-chicoric acid (L-CA and D-CA) and their respective tetra-acetyl esters inhibit the replication of HIV-1 (III(B) and NL4.3) and HIV-2 (ROD) in MT-4 cells at a 50% effective concentration (EC(50)) ranging from 1.7 to 70.6 microM. In a time-of-addition experiment, L-CA, D-CA, L-CATA, and D-CATA were found to interfere with an early event in the viral replication cycle. Moreover, L-CA, D-CA, and their analogs did not inhibit the replication of virus strains that were resistant toward polyanionic and polycationic compounds at subtoxic concentrations. Furthermore, HIV-1 strains resistant to L-CA and D-CA were selected in the presence of L-CA and D-CA, respectively. Mutations were found in the V2, V3, and V4 loop region of the envelope glycoprotein gp120 of the L-CA and D-CA-resistant NL4.3 strains that were not present in the wild-type NL4.3 strain. Recombination of the gp120 gene of the L-CA and D-CA resistant strain in a NL4.3 wild-type molecular clone fully rescued the phenotypic resistance toward L-CA and D-CA. No significant mutations were detected in the integrase gene of the drug-resistant virus strains. Although inhibition of HIV integrase activity by L-CA and its derivatives was confirmed in an oligonucleotide-driven assay, integrase carrying the G140S mutation was inhibited to the same extent as the wild-type integrase.

HIV-1 gp120 and chemokines activate ion channels in primary macrophages through CCR5 and CXCR4 stimulation

HIV type 1 (HIV-1) uses the chemokine receptors CCR5 and CXCR4 as coreceptors for entry into target cells. Here we show that the HIV-1 envelope gp120 (Env) activates multiple ionic signaling responses in primary human macrophages, which are important targets for HIV-1 in vivo. Env from both CCR5-dependent JRFL (R5) and CXCR4-dependent IIIB (X4) HIV-1 opened calcium-activated potassium (K(Ca)), chloride, and calcium-permeant nonselective cation channels in macrophages. These signals were mediated by CCR5 and CXCR4 because macrophages lacking CCR5 failed to respond to JRFL and an inhibitor of CXCR4 blocked ion current activation by IIIB. MIP-1beta and SDF-1alpha, chemokine ligands for CCR5 and CXCR4, respectively, also activated K(Ca) and Cl(-) currents in macrophages, but nonselective cation channel activation was unique to gp120. Intracellular Ca(2+) levels were also elevated by gp120. The patterns of activation mediated by CCR5 and CXCR4 were qualitatively similar but quantitatively distinct, as R5 Env activated the K(Ca) current more frequently, elicited Cl(-) currents that were approximately 2-fold greater in amplitude, and elevated intracellular Ca(+2) to higher peak and steady-state levels. Env from R5 and X4 primary isolates evoked similar current responses as the corresponding prototype strains. Thus, the interaction of HIV-1 gp120 with CCR5 or CXCR4 evokes complex and distinct signaling responses in primary macrophages, and gp120-evoked signals differ from those activated by the coreceptors' chemokine ligands. Intracellular signaling responses of macrophages to HIV-1 may modulate postentry steps of infection and cell functions apart from infection.

Potent anti-HIV (type 1 and type 2) activity of polyoxometalates: structure-activity relationship and mechanism of action

A series of polyoxometalates have been synthesized and evaluated for their inhibitory effects on HIV-1(III(B)) and HIV-1(ROD) replication in MT-4 cells. All compounds showed activity against HIV-1 and HIV-2, but the antiviral potency of the heteropolytungstates varied considerably depending on their chemical structure. The antiviral activity of single, double, and triple Keggin-type of compounds against HIV-1(III(B)) replication was comparable (IC(50): 0.4-0.5 microgram/mL), whereas HIV-2(ROD) appeared to become less sensitive with the increasing number of Keggin structures per compound. The same trend was observed for single and double Dawson structures. Some of these compounds were examined for their inhibitory effect on the replication of HIV-1(RF) and SIV(MAC(251)) in MT-4 cells. Their anti-HIV-1(RF) and anti-SIV(MAC(251)) potencies were comparable to those for the HIV-1(III(B)) or HIV-2(ROD) strain, respectively. The polyoxometalates represent a class of polyanionic compounds, which block the binding of the envelope glycoprotein gp120 of HIV to CD4(+) cells. The compounds interfered with the binding of anti-CD4 mAb to the OKT4A/Leu3a epitope of the CD4 receptor, compound 24 being the most active in this regard, and inhibited the binding of anti-gp120 mAb to infected MT-4 cells. None of the polyoxometalates inhibited the binding of a specific CXCR4 mAb to SUP-T1 cells, suggesting that they do not interact with CXCR4, the main co-receptor for T-tropic HIV strains, and thus act as virus binding, and not as fusion, inhibitors.

CXC-chemokine receptor 4 is not a coreceptor for human herpesvirus 7 entry into CD4(+) T cells

Human herpesvirus 7 (HHV-7) is a T-lymphotropic virus which utilizes the CD4 receptor as its main receptor to enter the target cells. Hence, HHV-7 can interfere with human immunodeficiency virus type 1 (HIV-1) infection in CD4(+) T cells. It was recently suggested that the CXC chemokine receptor 4 (CXCR4), which was found to be a crucial coreceptor for T-tropic HIV-1 strains, may also play a role in the HHV-7 infection process. However, the results presented here demonstrate that CXCR4 is not involved in HHV-7 infection. The natural ligand of CXCR4, SDF-1alpha, was not able to inhibit HHV-7 infection in SupT1 cells or in CD8(+) T-cell-depleted peripheral blood mononuclear cells. Also, AMD3100, a specific CXCR4 antagonist with potent antiviral activity against T-tropic HIV strains (50% inhibitory concentration ¿IC(50), 1 to 10 ng/ml), completely failed to inhibit HHV-7 infection (IC(50), >250 microg/ml). Thus, two different agents known to specifically interact with CXCR4 were not able to inhibit HHV-7 infection. Other T-lymphoid cell lines, expressing both CD4 and CXCR4 (e.g., HUT-78 and MT-4) could not be infected by HHV-7. In addition, the CD4-transfected cell lines HOS. CD4 and U87.CD4 and the CD4/CXCR4 double-transfected cell lines HOS. CD4.CXCR4 and U87.CD4.CXCR4 were not infectable with HHV-7. Also, we found no down-regulation of surface-bound or intracellular CXCR4 in HHV-7-infected CD4(+) T cells. As compared to uninfected SupT1 cells, stromal cell-derived factor 1alpha (SDF-1alpha)/CXCR4-mediated intracellular calcium flux was unchanged in SupT1 cells that were acutely or persistently infected with HHV-7. All these data argue against CXCR4 as a receptor involved in the HHV-7 infection process.