Potent inhibition of HIV type 1 replication by an antiinflammatory alkaloid, cepharanthine, in chronically infected monocytic cells

Cepharanthine is a biscoclaurine alkaloid isolated from Stephania cepharantha Hayata and has been shown to have antiinflammatory, antiallergic, and immunomodulatory activities in vivo. As several inflammatory cytokines and oxidative stresses are involved in the pathogenesis of HIV-1 infection, we investigated the inhibitory effects of cepharanthine on tumor necrosis factor alpha (TNF-alpha)- and phorbol 12-myristate 13-acetate (PMA)-induced HIV-1 replication in chronically infected cell lines. Two chronically HIV-1-infected cell lines, U1 (monocytic) and ACH-2 (T lymphocytic), were stimulated with TNF-alpha or PMA and cultured in the presence of various concentrations of the compound. HIV-1 replication was determined by p24 antigen level. The inhibitory effects of cepharanthine on HIV-1 long terminal repeat (LTR)-driven gene expression and nuclear factor kappaB (NF-kappaB) activation were also examined. Cepharanthine dose dependently inhibited HIV-1 replication in TNF-alpha- and PMA-stimulated U1 cells but not in ACH-2 cells. Its 50% effective and cytotoxic concentrations were 0.016 and 2.2 microg/ml in PMA-stimulated U1 cells, respectively. Cepharanthine was found to suppress HIV-1 LTR-driven gene expression through the inhibition of NF-kappaB activation. These results indicate that cepharanthine is a highly potent inhibitor of HIV-1 replication in a chronically infected monocytic cell line. Since biscoclaurine alkaloids, containing cepharanthine as a major component, are widely used for the treatment of patients with various inflammatory diseases in Japan, cepharanthine should be further pursued for its chemotherapeutic potential in HIV-1-infected patients.     

Interleukin 1alpha stimulates lactate dehydrogenase A expression and lactate production in cultured porcine sertoli cells

By using cultured porcine Sertoli cells as a model, the action of interleukin 1alpha (IL-1alpha) on lactate production and the site of this action were studied. IL-1alpha stimulated Sertoli cell lactate production in a time- and dose-dependent manner (with a half-maximal effect [ED50] of 6 pM). Two major sites involved in IL-1alpha action were identified. First, IL-1alpha was shown to increase the uptake of glucose substrate in a time- and dose-dependent manner. The maximal effect, with an ED50 of 10 pM, was observed after 24 h of treatment. Second, IL-1alpha increased the activity of the lactate dehydrogenase (LDH) A4 isoform, which is involved in the conversion of pyruvate into lactate. This increase in LDH A4 activity was detected at 12 h and was maximal, with an ED50 of 9 pM, after 24-h treatment with IL-1alpha. The increase was related to an increase in LDH A4 expression, since IL-1alpha stimulated LDH A mRNA (size: 1.5 kilobases, evidenced through Northern blotting analysis) in a dose- and time-dependent manner. Assuming that IL-1alpha might be produced in the seminiferous tubules by both Sertoli and germ cells, which utilize lactate for their energy metabolism, we suggest that these results together show 1) that the cytokine may represent a signal in the metabolic cooperation existing between Sertoli cells and germ cells, and 2) that a redistribution of LDH isoforms in favor of LDH A4 under IL-1alpha control is a key mechanism(s) in such cooperation used by germ cells to enhance lactate production in Sertoli cells.     

HIV type 1 extracellular Tat protein stimulates growth and protects cells of BK virus/tat transgenic mice from apoptosis

Cells from BKV/tat transgenic mice were characterized for their tumorigenic phenotype in nude and syngeneic BDF mice. The results indicate that the BKV/tat recombinant transgene has a weak tumorigenic potential, mostly predisposing to oncogenesis, and that second events are required for the development of tumorigenicity. Tat is endogenously produced and released by tumor cells. It is taken up by recipient cells directly from the culture medium, without need of cell to cell contact. Extracellular Tat stimulates proliferation of cells from BKV/tat transgenic mice and protects them from apoptosis under conditions of serum starvation. Our results are in agreement with a model in which Tat induces its effects on target cells in two different ways. Growth promotion may require interaction of extracellular Tat with surface receptors eliciting a signal for cell proliferation, whereas intranuclear localization of Tat is necessary for transactivation of viral and cellular genes.     

Chronically HIV-1-infected monocytic cells induce apoptosis in cocultured T cells

We have previously developed a human macrophage hybridoma model system to study the effect of HIV-1 infection on monocytic function. Upon coculture of one chronically (35 days postinfection) HIV-1-infected human macrophage hybridoma cell line, 43HIV, there was a dose-dependent decrease in the viability of cocultured Ag-stimulated T cells associated with an increase in DNA strand breaks. Enhanced apoptosis was determined by labeling with biotinylated dUTP and propidium iodide, increased staining with annexin V, increased side light scatter and expression of CD95, and decreased forward light scatter and expression of Bcl-2. There was also increased DNA strand breaks as determined by propidium iodide staining in unstimulated T cells cocultured with 43HIV and in T cells stimulated with anti-CD3 mAb and PHA. Pretreatment with 5145, a human polyclonal anti-gp120 Ab that recognizes the CD4 binding region, as well as with an anti-Fas ligand mAb blocked apoptosis in CD4+ T cells but not in CD8+ T cells. A soluble factor with a Mr below 10,000 Da was defined that induced apoptosis in CD4+ and CD8+ T cells and B cells. SDS-PAGE analysis of the active fractions revealed a band of 6000 Da that, after electroelution, had proapoptotic activity. The pI of the activity was estimated to be between 6.5 and 7.0. In conclusion, chronically HIV-1-infected monocytic cells induce apoptosis in bystander-, Ag-, anti-CD3-, and mitogen-stimulated T cells by multiple factors, which may contribute to the depletion of lymphocytes induced by HIV-1.     

Inhibition of human immunodeficiency type 1 virus replication in monocytic U-937 cells by superinfection with Chlamydia trachomatis

Status epilepticus is a neurological emergency associated with substantial morbidity and mortality. Experimental and clinical investigations suggest that prolonged seizure activity is associated with injury to vulnerable neurons. Compounds with neuroprotective properties may minimize such injury. Existing methods of inducing experimental status epilepticus result in seizure activity of variable duration and neuronal injury of variable degree. To minimize such variability, status epilepticus may be stopped with anticonvulsants, but this limits the ability to screen for independent neuroprotective properties. We have developed a simple and reliable non-pharmacological model of limbic status epilepticus in which the duration of status epilepticus is under direct experimental control. Status epilepticus is induced by continuous, unilateral hippocampal stimulation. Using this model, the degree of hippocampal pyramidal cell injury varies in direct proportion to status epilepticus duration across a range of 15-140 min. A progressive sequence of EEG changes unfolds with increasing status epilepticus duration, resembling that seen in other models. This model may serve as a reference against which the effects of potential neuroprotective compounds can be studied.     

Interactions of monocytic cells with human endothelial cells stimulate monocytic metalloproteinase production

Monocyte-endothelial cell interactions play an important role in the early stages of atherosclerosis, and it is hypothesized that regulation of metalloproteinase production by these interactions contributes to this pathological process. The effects of monocytic cell-endothelial cell interactions on monocytic metalloproteinase production were investigated using an in vitro system, focusing on the role of endothelial cell secretions and physical contact as effectors in the regulation of monocytic metalloproteinase expression. Human umbilical vein endothelial cells (HUVECs) and the human monocytic cell line THP-1 were used, and changes in the levels of THP-1 metalloproteinase secretion and mRNA were measured. When THP-1 cells were incubated for 18 hours with HUVEC conditioned medium (CM), a four- to eightfold induction of the metalloproteinase MMP-9 was observed at both the mRNA and protein levels; however, levels of another metalloproteinase, MMP-2, were unaffected. The induction of MMP-9 by HUVEC CM was confirmed using freshly isolated human monocytes. A sevenfold increase in MMP-9 levels was observed with apically collected HUVEC CM but not with basally collected CM. THP-1 cells incubated with paraformaldehyde-fixed HUVECs and isolated HUVEC plasma membranes showed an eightfold increase in MMP-9 levels, and measurements of MMP-9 activity found in THP-1 conditioned medium due to either HUVEC contact or HUVEC CM showed a threefold increase. The molecular weight of the endothelial secreted effector molecule(s) was determined to be 30 +/- 6 kd. The data show that endothelial cells through the release of soluble factors and through direct contact with monocytic cells regulate monocytic metalloproteinase production, which has implications for the atherogenic process.     

Effect of ethanol on monocytic function in human immunodeficiency virus type 1 infection

We have developed a novel system to study monocytic function after human immunodeficiency virus type 1 (HIV-1) infection by infecting a series of human macrophage hybridoma cell lines with HIV-1. Since ethanol has detrimental effects on immune function, we investigated the effect of ethanol and its metabolites acetaldehyde and acetate on monocytic function by utilizing one human macrophage hybridoma cell line, clone 43, as well as primary monocytes. Pretreatment of clone 43 and primary monocytes with ethanol and its metabolites resulted in diminished accessory cell function for mitogen-, anti-CD3-, and antigen-induced T-cell proliferation. The decreased accessory cell function was associated with reduced interleukin 1alpha (IL-1alpha), IL-1beta, and tumor necrosis factor alpha production with loss of intracellular cytokine and mRNA production and the induction of transforming growth factor beta. In ethanol-, acetaldehyde-, and acetate-treated HIV-1-infected clone 43 cells (43HIV), there was a more rapid loss (3 days after infection) of accessory cell function at a lower infecting dose of HIV-1 than that in untreated 43HIV cells. We also observed a more rapid loss of surface class II antigen expression in the ethanol-, acetaldehyde-, and acetate-treated 43HIV cells, but no change in surface expression of CD80 or CD86. Ethanol-induced impairment of monocytic function may compound the immunologic defects of AIDS, making the infected individual more susceptible to the complications of the disease.     

Vpr stimulates viral expression and induces cell killing in human immunodeficiency virus type 1-infected dividing Jurkat T cells

In this study we investigated the effects of Vpr during human immunodeficiency virus (HIV) infection of proliferating Jurkat T cells by using a vesicular stomatitis virus envelope G glycoprotein pseudotyped HIV superinfection system. We observe that the expression of Vpr results in a severe reduction in the life span of HIV type 1 (HIV-1)-infected dividing T cells in culture. In agreement with a recent report (S. A. Stewart, B. Poon, J. B. M. Jowett, and I. S. Chen, J. Virol. 71:5579-5592, 1997), we show that events characteristic of apoptotic cell death are involved in the Vpr-mediated cytopathic effects. Our results also show that infection with viruses expressing the wild-type vpr gene results in an increase in viral gene expression and production. Interestingly, the effects of Vpr on cell viability and on viral gene expression both correlate with the ability of the protein to induce a cell cycle arrest in the G2/M phase. Mutagenesis analyses show that the C terminus of Vpr is essential for these biological activities. Although the role of Vpr is currently associated with the infection of nondividing cells, our results suggest that Vpr can also directly increase viral replication in vivo in infected dividing T cells. Furthermore, these in vitro observations suggest that Vpr-mediated cytotoxic effects could contribute to the CD4+ depletion associated with AIDS progression.     

HIV type 1 Tat protein inhibits interleukin 12 production by human peripheral blood mononuclear cells

HIV-1 Tat protein, which trans-activates HIV-1 expression, exerts many effects on host immune function. Meanwhile, PBMCs and pulmonary macrophages from HIV-1-infected patients produce only a small amount of IL-12, which plays an essential role in the development of helper T type 1 (Th1) cells, and in the generation of cytotoxic T lymphocytes. We examined the possibility that Tat suppresses IL-12 production by PBMCs from healthy donors. Tat significantly inhibited IL-12 production by human PBMCs stimulated with Staphylococcus aureus Cowan 1 strain (SAC) at concentrations between 5 and 40 ng/ml. Immunoabsorption by using polyclonal antibody to Tat abolished the suppression of the IL-12 production by Tat. Tat at the same concentrations did not affect IL-10, IL-6, or TNF-alpha production. Other HIV-1 proteins (Nef and gp120) did not influence IL-12 production. Tat also suppressed the expression of mRNA encoding the p40 chain of IL-12, whereas it did not affect the expression of mRNA encoding IL-10 and beta-actin. IL-12 production by monocytes, separated from PBMCs by the adhesion method, was also inhibited by Tat. These results suggest that Tat protein is one of the main causes of decreased IL-12 production by PBMCs (mostly by monocytes) from HIV-1-infected individuals.     

Comparative uptake of sparfloxacin and ciprofloxacin into human THP 1 monocytic cells

TachoComb is a new, ready-to-use hemostatic agent consisting of a collagen sheet coated on one side with human fibrinogen, bovine thrombin, and bovine aprotinin. The product was used in 125 surgical operations (vascular, hepatic, urological and ENT) in which secondary hemostasis was required. It was placed over the cut surface or over the edges of the wound. The investigating surgeons expressed their opinion on the intra- and postoperative hemostatic efficacy, and routine laboratory tests were done postoperatively. TachoComb had good hemostatic efficacy in 67.2% of cases, and very good in 22.4%. No noteworthy systemic changes were observed. As an adjuvant to obtain complete hemostasis in surgery, TachoComb is effective, practical and quick to use, and is very well tolerated.     

Interleukin 1 (IL-1) causes changes in lateral and rotational mobilities of IL-1 type I receptors

To investigate IL-1-dependent interactions of IL-1 type I (IL-1 RI) receptors on intact cells, lateral and rotational mobilities and detergent insolubility were investigated. Lateral mobility was measured by fluorescence photobleaching recovery, using a Cy3-modified, noncompetitive mAb specific for IL-1RI (M5) bound to wild-type IL-1 RI or mutant IL-1 RI with a truncated cytoplasmic tail. Addition of IL-1 causes significant reduction in the mobile fraction of wild-type IL-1 RI for two different transfected cell lines. For the mutant IL-1 RI, no significant decrease in response to IL-1 is observed, indicating that the missing cytoplasmic segment is involved in IL-1-dependent interactions of IL-1 RI that lead to reduced lateral mobility on the cell surface. The rotational mobility of IL-1 RI was assessed with phosphorescence anisotropy decay measurements using erythrosin-labeled M5. IL-1 decreases the rotational mobility of cell surface IL-1 RI on the microsecond time scale and also increases the initial anisotropy, indicating loss in segmental motion. Measurements of resistance to solubilization by Triton X-100 showed that IL-1 binding increases the fraction of IL-1 RI sedimenting with cytoskeletal residues. The IL-1 receptor antagonist protein (IL-1ra) causes partial effects in reducing rotational mobility and increasing detergent insolubility of M5-lableled IL-1 RI, indicating that this ligand causes structural changes in the presence of the dimerizing M5 mAb. These ligand-dependent physical interactions of IL-1 RI on the cell surface may be related to signal initiation by this receptor.     

Transforming growth factor-beta1 stimulates protein kinase A in mesangial cells

We recently demonstrated that transforming growth factor-beta (TGF-beta) stimulates phosphorylation of the type I inositol 1,4, 5-trisphosphate receptor (Sharma, K., Wang, L., Zhu, Y., Bokkala, S., and Joseph, S. (1997) J. Biol. Chem. 272, 14617-14623), possibly via protein kinase A (PKA) activation in murine mesangial cells. In the present study, we evaluated whether TGF-beta stimulates PKA activation. Utilizing a specific PKA kinase assay, we found that TGF-beta increases PKA activity by 3-fold within 15 min of TGF-beta1 treatment, and the enhanced kinase activity was completely reversed by the inhibitory peptide for PKA (PKI; 1 microM). In mesangial cells transfected with a PKI expression vector, enhanced PKA activity could not be demonstrated with TGF-beta1 treatment. TGF-beta1 was also found to stimulate translocation of the alpha-catalytic subunit of PKA to the nucleus by Western analysis of nuclear protein as well as by confocal microscopy. TGF-beta1-mediated phosphorylation of cAMP response element-binding protein was completely reversed by H-89 (3 microM), a specific inhibitor of PKA. Stimulation of fibronectin mRNA by TGF-beta1 was also attenuated in cells overexpressing PKI. We thus conclude that TGF-beta stimulates the PKA signaling pathway in mesangial cells and that PKA activation contributes to TGF-beta stimulation of cAMP response element-binding protein phosphorylation and fibronectin expression.     

Human submandibular saliva specifically inhibits HIV type 1

This study was performed to investigate the possible association between preeclampsia and the plasma concentrations of Lp(a) lipoprotein and TGF-beta1 in a large series of patients. Additionally, correlation between the concentrations of these molecules and the severity of preeclampsia or fetal growth retardation was evaluated. Following clinical examination and biochemical analyses, both electroimmunoassay and RIA technique were used for quantitative determinations of plasma Lp(a) lipoprotein. ELISA technique was used to measure the active form of TGF-beta1 in plasma of pregnant normotensive and preeclamptic women. We examined 154 women with preeclampsia (preeclampsia group) and 76 healthy, pregnant normotensive women (control group). The preeclampsia group was further divided into the following subgroups: mild preeclampsia, severe preeclampsia and preeclampsia with fetal growth retardation. Plasma levels of Lp(a) lipoprotein were lower in the total preeclampsia group as well as in all preeclampsia subgroups (5.45+/-7.41, 5.58+/-8.02, 5.08+/-5.38, and 4.32+/-5.28 mg/dl in the total preeclampsia group, and in subgroups with mild preeclampsia, severe preeclampsia, and preeclampsia with fetal growth retardation, respectively) than in the control group (7.84+/-9.26 mg/dl) as determined by quantitative electroimmunoassay. Corresponding results were obtained with a radioimmunoassay (166.03+/-200.2 U/l in the total preeclampsia group vs. 229.18+/-257.7 U/l in controls). There was good correlation between the two methods used for Lp(a) lipoprotein measurement. The differences between controls and the total preeclampsia group as well as each preeclampsia subgroup were statistically significant by a non-parametric test (one-way Kruskal-Wallis test). Plasma concentrations of the active form of TGF-beta1 were increased in all preeclampsia subgroups as well as in the total group (5.63+/-1.68 ng/ml) compared to controls (4.67+/-1.33 ng/ml). This increase in TGF-beta1 was statistically highly significant. Plasma concentrations of Lp(a) lipoprotein and the active form of TGF-beta1 did not differ significantly between the preeclampsia subgroups. The outcome of this study may suggest involvement of both parameters in the pathophysiology of preeclampsia and may substantiate the notion of a multifactorial etiology of the disease.     

Thrombin stimulates expression of tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in cultured human vascular smooth muscle cells

The effect of thrombin on the fibrinolytic potential of human vascular smooth muscle cells (SMC) in culture was studied. SMC of different origin responded to thrombin treatment with a dose and time dependent increase in tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) levels in both cell lysates and conditioned media with maximum effects achieved at 10-20 IU/ml thrombin. PAI-1 antigen levels also increased in the extracellular matrix of thrombin treated SMC. PAI-2 levels in cell lysates of such SMC were not affected by thrombin. The effect was restricted to active thrombin, since DFP-thrombin and thrombin treated with hirudin showed no increasing effect on t-PA and PAI-1 levels in SMC. Enzymatically active thrombin also caused a four-fold increase in specific PAI-1 mRNA and a three-fold increase in t-PA mRNA. Furthermore we demonstrated the presence of high and low affinity binding sites for thrombin on the surface of SMC with a KD = 4.3 x 10(-10)M and 9.0 x 10(4) sites per cell and a KD = 0.6 x 10(-8) M and 5.8 x 10(5) sites per cell respectively. Thrombin could come in contact with SMC in case of vascular injury or following gap formation between endothelial cells. Our data support the idea that besides its known proliferative effect for SMC, thrombin could also modulate their fibrinolytic system.     

HIV type 1 resistance in Kenyan sex workers is not associated with altered cellular susceptibility to HIV type 1 infection or enhanced beta-chemokine production

A small group of women (n = 80) within the Nairobi-based Pumwani Sex Workers Cohort demonstrates epidemiologic resistance to HIV-1 infection. Chemokine receptor polymorphisms and beta-chemokine overproduction have been among the mechanisms suggested to be responsible for resistance to HIV-1 infection. This study attempts to determine if any of those mechanisms are protecting the HIV-1-resistant women. Genetic analysis of CCR5 and CCR3 from the resistant women demonstrated no polymorphisms associated with resistance. Expression levels of CCR5 among the resistant women were shown to be equivalent to that found in low-risk seronegative (negative) controls, while CXCR4 expression was greater among some of the resistant women. In vitro infection experiments showed that phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMCs) from resistant women were as susceptible to infection to T cell- and macrophage-tropic North American and Kenyan HIV-1 isolates as were the PBMCs from negative controls. No significant difference in circulating plasma levels of MIP-1alpha and MIP-1beta were found between the resistant women and negative or HIV-1-infected controls. In vitro cultures of media and PHA-stimulated PBMCs indicated that the resistant women produced significantly less MIP-1alpha and MIP-1beta than did negative controls and no significant difference in RANTES levels were observed. In contrast to studies in Caucasian cohorts, these data indicate that CCR5 polymorphisms, altered CCR5 and CXCR4 expression levels, cellular resistance to in vitro HIV-1 infection, and increased levels of beta-chemokine production do not account for the resistance to HIV-1 infection observed among the women of the Pumwani Sex Workers Cohort.