Synthesis and construction of a novel multiple peptide conjugate system: strategy for a subunit vaccine design

We describe the design and synthesis of a novel well characterized multi-peptide conjugate (MPC) system containing antigens from human malaria parasite and the Tat protein of HIV type-1 (HIV-1-Tat). Construction of the MPC utilizes Fmoc solid-phase peptide synthesis coupled with solution chemistry. In the first phase, a core template that serves as primary anchor for the synthesis and attachment of multiple antigens is synthesized. Serine(trityl) and multiple lysine branches with epsilon groups blocked during chain assembly are incorporated forming a tetrameric core. Cysteine whose side chain thiol serves to couple haloacetyl or S-protected haloacetyl peptides is added to complete assembly of the core template. Modification to the coupling solvent, addition of key amino acid derivatives (N-[1-hydroxy-4-methoxybenzyl]) in the peptide sequence allows the synthesis of base peptides on the core template with molecular mass greater than 7500 kDa. Base peptides are then reacted with high performance liquid chromatography purified haloacetyl peptides to generate multiple peptide conjugates with molecular masses of 10 to 13 kDa. MPC constructs thus formed are further characterized by matrix assisted laser desorption-time of flight mass spectroscopy (MALDI-MS), amino acid analysis, size exclusion chromatography, and SDS-polyacrylamide gel electrophoresis (PAGE). To our knowledge, this is the first report describing a chemically well defined multiple conjugate system with potential for development of synthetic subunit vaccines.

HIV-1 infects and alters immune function of a monocyte subset expressing low CD14 surface phenotype

Monocytes represent a leukocyte subset that express high levels of CD14 on their surface (CD14-high). These cells play a critical role in the pathogenesis of HIV-1 infection. In the present study, we have identified a monocyte subset expressing an extremely low level of CD14 (CD14-low), and examined their susceptibility to HIV-1 infection. Phenotypic analysis by flow cytometry of these cells revealed a low level of CD4, but the absence of CD3, CD14, CD19, and CD83 surface markers. Both CD14-low and CD14-high cell populations expressed CD13 and CD33 markers on their surface, suggesting these cells to be of myeloid origin. Morphologically, CD14-low cells were indistinguishable from CD14-high cells. CD14-low cells were susceptible to infection with a monocytotropic strain of HIV-1 (HIVADA). However, like CD14-high monocytes, CD14-low cells could not be productively infected with a T cell tropic strain of HIV-1 (H9/HTLV(IIIB)). Similar to CD14-high monocytes, CD14-low cells were capable of inducing antigen-stimulated CD4+ T-cell proliferation. HIV-1 infection substantially reduced their ability to induce antigen-stimulated T-cell proliferation. These data indicate that CD14-low cells belong to the monocyte lineage and may play an important role in the immunopathogenesis of HIV-1 infection.

Human immunodeficiency virus-1-tat induces matrix metalloproteinase-9 in monocytes through protein tyrosine phosphatase-mediated activation of nuclear transcription factor NF-kappaB

We have previously shown that human immunodeficiency virus (HIV)-1-tat induces the production of matrix metalloproteinase-9 (MMP-9) in human monocytes by a mechanism that is not understood. In the present report, we demonstrate that HIV-tat-induced expression of MMP-9 is blocked by inhibitors of protein tyrosine phosphatases (PTPases). PTPase inhibitors also blocked HIV-tat-induced nuclear transcription factor NF-kappaB activation and IkappaBalpha degradation required for MMP-9 induction. These results suggest that HIV-tat induces MMP-9 in human monocytes through activation of PTPase and NF-kappaB.

Cutting edge: a short polypeptide domain of HIV-1-Tat protein mediates pathogenesis

HIV-1 encodes the transactivating protein Tat, which is essential for virus replication and progression of HIV disease. However, Tat has multiple domains, and consequently the molecular mechanisms by which it acts remain unclear. In this report, we provide evidence that cellular activation by Tat involves a short core domain, Tat21-40, containing only 20 aa including seven cysteine residues highly conserved in most HIV-1 subtypes. Effective induction by Tat21-40 of both NF-kappaB-mediated HIV replication and TAR-dependent transactivation of HIV-long terminal repeat indicates that this short sequence is sufficient to promote HIV infection. Moreover, Tat21-40 possesses potent angiogenic activity, further underscoring its role in HIV pathogenesis. These data provide the first demonstration that a 20-residue core domain sequence of Tat is sufficient to transactivate, induce HIV replication, and trigger angiogenesis. This short peptide sequence provides a potential novel therapeutic target for disrupting the functions of Tat and inhibiting progression of HIV disease.

Wound-healing risk factors after open reduction and internal fixation of calcaneal fractures

This retrospective study investigated outcomes of wound healing in a series of 63 consecutive patients with 64 fractures of the calcaneus who underwent open reduction and internal fixation done by two surgeons experienced in this fracture during a 3-year period. Thirty-nine patients were managed preoperatively as outpatient referrals before surgery. Twenty-four patients were admitted directly to the trauma service and were managed as inpatients preoperatively. Minimum patient follow-up was 6 months, with an average follow-up of 18 months. A trend correlating the time between injury and operative intervention with the incidence of complications in wounds was noted; the incidence rose in patients who underwent surgery >5 days after their injury. Two-layered closures had a lower incidence of dehiscence compared to single-layered tension-relieving sutures. Patients with a higher body-mass index (BMI) (kg/ m2) took longer to heal their wounds. Strong trends were noted to link BMI and severity of fractures. In the outpatient group, a history of active smoking preoperatively correlated with increased time to wound healing. In 43 patients, there were no wound-healing complications. In 21 feet, there were varying degrees of wound dehiscence. Average wound healing took 47 days. Risk factors for complications in the wound after calcaneal open reduction and internal fixation include single layered closure, high BMI, extended time between injury and surgery, and smoking. Age, type of immobilization, medical illness (including diabetes), type of bone graft, or use of a Hemovac did not influence wound healing.

Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) inhibits TNF-induced NF-kappaB activation, IkappaB degradation, and expression of cell surface adhesion proteins in human vascular endothelial cells

Most inflammatory agents activate nuclear transcription factor-kappaB (NF-kappaB) which results in expression of genes for cytokines, adhesion molecules, and enzymes involved in amplification and perpetuation of inflammation. Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) is an active component from the roots of Polygonum cuspidatum that has been reported to exhibit antiinflammatory properties but the mechanism is not known. In the present study we investigated the effects of emodin on the activation of NF-kappaB in human umbelical vein endothelial cells (EC). Treatment of EC with TNF activated NF-kappaB; preincubation with emodin inhibited this activation in a dose- and time-dependent manner. Emodin did not chemically modify NF-kappaB subunits but rather inhibited degradation of IkappaB, an inhibitory subunit of NF-kappaB. Since the promoter regions of ICAM-1, VCAM-1, and ELAM-1 contain NF-kappaB binding sites and these adhesion molecules are involved in the attachment of leukocytes to EC, the effect of emodin on the adhesion of monocytes to EC and the expression of these adhesion molecules was also studied. Treatment of EC with TNF for 6 h increased the adhesion of monocytes to EC, which correlated with increases in cell surface expression of ICAM-1, VCAM-1 and ELAM-1. Pretreatment of EC for 1 h with emodin inhibited both monocyte-EC attachment and expression of ICAM-1, ELAM-1 and VCAM-1. These results indicate that emodin is a potent inhibitor of NF-kappaB activation and expression of adhesion molecules and thus could be useful in treating various inflammatory diseases.

HIV-Tat protein activates c-Jun N-terminal kinase and activator protein-1

Human immunodeficiency virus-1 tat (HIV-tat) protein, like other proinflammatory cytokines (such as TNF), activates a wide variety of cellular responses, some of which play a critical role in progression of HIV infection. Whether HIV-tat, like TNF, also activates c-Jun N-terminal kinase (JNK) and the transcription factor activator protein (AP)-1 is not known. We show that treatment of human histiocytic lymphoma U937 cells with the HIV-tat protein causes activation of JNK and AP-1 in a time- and dose-dependent manner. Transfection of a T cell line, H9 cells with the HIV-tat gene also resulted in an activation of JNK that was not further increased by treatment of cells with exogenous HIV-tat protein. Neutralizing Ab against HIV-tat inhibited the HIV-tat-mediated JNK activation. The activation of JNK by HIV-tat appears to be mediated through generation of free radical species, since pretreatment of cells with N-acetylcysteine (NAC) abolished the effect. Overall our results demonstrate that HIV-tat activates JNK and AP-1, which may contribute to the pathogenesis of AIDS.

Curcumin (Diferuloylmethane) inhibition of tumor necrosis factor (TNF)-mediated adhesion of monocytes to endothelial cells by suppression of cell surface expression of adhesion molecules and of nuclear factor-kappaB activation

Recruitment of leukocytes by endothelial cells and their subsequent migration from the vasculature into the tissue play major roles in inflammation. In the present study, we investigated the effect of curcumin, an antiinflammatory agent, on the adhesion of monocytes to human umbilical vein endothelial cells (EC). Treatment of EC with tumor necrosis factor (TNF) for 6 hr augmented the adhesion of monocytes to EC, and this adhesion was due to increased expression of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule-1 (ELAM-1). Pretreatment of EC for 1 hr with curcumin completely blocked their adhesion to monocytes, as well as the cell surface expression of ICAM-1, VCAM-1, and ELAM-1 in EC. Although curcumin inhibited adhesion even when administered 1 hr after TNF treatment, maximum inhibition occurred when added either 1 hr before or at the same time as TNF. As the induction of various adhesion molecules by TNF requires activation of the transcription factor NF-kappaB, the effect of curcumin on the activation of this factor in the EC was also investigated. A 30-min treatment with TNF activated NF-kappaB; the activation was inhibited in a concentration-dependent manner by pretreatment with curcumin, indicating that NF-kappaB inhibition may play a role in the suppression of expression of adhesion molecules in EC. Our results demonstrate that the antiinflammatory properties of curcumin may be attributable, in part, to inhibition of leukocyte recruitment.

Activation of monocytes by HIV-Tat treatment is mediated by cytokine expression

Treatment of primary monocytes with soluble HIV-Tat protein is associated with increased monocyte metalloproteinase-9 (MMP-9) expression and enhanced beta 2 integrin expression that increases monocyte/endothelial adhesion. These alterations require greater than 12 h of HIV-Tat treatment, suggesting the involvement of intermediate factors. Thus, we have examined the role of cytokines in the HIV-Tat-induced alteration of monocyte function. Treatment of monocytes with HIV-Tat rapidly up-regulated the production of IL-1 beta, IL-6, IL-8, and TNF-alpha, but not IL-3, granulocyte-macrophage CSF, basic fibroblast growth factor, or macrophage-inflammatory protein-1 alpha, and was associated with up-regulation of the corresponding cytokine mRNA. Inclusion of neutralizing anti-cytokine Abs to IL-1 beta or TNF-alpha during the HIV-Tat pretreatment period significantly inhibited the HIV-Tat-induced increase in MMP-9 production, monocyte/endothelial adhesion, and monocyte-dependent endothelial damage. In contrast, neutralizing Abs against IL-6 and IL-8 had no effect. The effects of HIV-Tat treatment, namely MMP-9 production, enhanced monocyte/endothelial cell adhesion, and monocyte-dependent endothelial damage, were mimicked by treating the monocytes with IL-1 beta or TNF-alpha, but not with IL-6 or IL-8. Therefore, the mechanism by which HIV-Tat activates monocyte function is dependent on HIV-Tat-induced production of cytokines (IL-1 beta and TNF-alpha).

Activation of monocytes by HIV-Tat treatment is mediated by cytokine expression

Treatment of primary monocytes with soluble HIV-Tat protein is associated with increased monocyte metalloproteinase-9 (MMP-9) expression and enhanced beta 2 integrin expression that increases monocyte/endothelial adhesion. These alterations require greater than 12 h of HIV-Tat treatment, suggesting the involvement of intermediate factors. Thus, we have examined the role of cytokines in the HIV-Tat-induced alteration of monocyte function. Treatment of monocytes with HIV-Tat rapidly up-regulated the production of IL-1 beta, IL-6, IL-8, and TNF-alpha, but not IL-3, granulocyte-macrophage CSF, basic fibroblast growth factor, or macrophage-inflammatory protein-1 alpha, and was associated with up-regulation of the corresponding cytokine mRNA. Inclusion of neutralizing anti-cytokine Abs to IL-1 beta or TNF-alpha during the HIV-Tat pretreatment period significantly inhibited the HIV-Tat-induced increase in MMP-9 production, monocyte/endothelial adhesion, and monocyte-dependent endothelial damage. In contrast, neutralizing Abs against IL-6 and IL-8 had no effect. The effects of HIV-Tat treatment, namely MMP-9 production, enhanced monocyte/endothelial cell adhesion, and monocyte-dependent endothelial damage, were mimicked by treating the monocytes with IL-1 beta or TNF-alpha, but not with IL-6 or IL-8. Therefore, the mechanism by which HIV-Tat activates monocyte function is dependent on HIV-Tat-induced production of cytokines (IL-1 beta and TNF-alpha).

Induction of endothelial cell surface adhesion molecules by tumor necrosis factor is blocked by protein tyrosine phosphatase inhibitors: role of the nuclear transcription factor NF-kappa B

Recent studies from our laboratory have indicated that protein tyrosine phosphatase (PTPase) inhibitors can down-modulate the tumor necrosis factor (TNF)-mediated activation of the nuclear transcription factor NF-kappa B in ML-1a, a monocytic cell line (Singh and Aggarwal, J. Biol. Chem. 1995: 270: 10631). Since TNF is one of the major inducers of various adhesion molecules in human endothelial cells and their expression is known to require the activation of NF-kappa B, we examined the effect of PTPase inhibitors on the TNF-mediated induction of intracellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and endothelial leukocyte adhesion molecule (ELAM)-1. Like ML-1a, human dermal microvessel endothelial cells (MVEC) treated with TNF rapidly activated (within 30 min) NF-kappa B; this effect was completely abolished by co-treatment with phenylarsine oxide (PAO), a specific inhibitor of PTPase. The induction of ICAM-1, VCAM-1, and ELAM-1 by TNF in MVEC occurred within 6 h and was also completely down-regulated by PAO in a dose-dependent manner. PAO was found to be effective even when added 3 h after TNF, suggesting a rapid mode of action of this inhibitor. Besides PAO, other inhibitors of PTPase, including pervanadate and diamide, also blocked TNF-dependent NF-kappa B activation and induction of all the three adhesion proteins. Consistent with these results, the attachment of monocytes to MVEC was also blocked by the PTPase inhibitors. Thus, overall, our results demonstrate that a PTPase is involved either directly or indirectly in the pathway leading to the induction of endothelial cell adhesion molecules by TNF. Because of their role in cell adhesion, PTPase may provide a novel target of drug development for treatment of inflammation, atherogenesis, and tumor metastasis.

Human immunodeficiency virus-1-tat protein induces the cell surface expression of endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 in human endothelial cells

Human vascular endothelial cells (EC) have been implicated in the dissemination of human immunodeficiency virus type-1 (HIV-1). HIV-1-tat, a viral gene product essential for HIV replication, has been shown to interact with different cell types, altering their growth and inducing gene expression. In the present report, we have examined the effect of HIV-tat on the expression of various adhesion molecules in human umbilical vein EC. Our results show that treatment of EC with HIV-tat induces the cell surface expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial leukocyte adhesion molecule-1 in a time- and dose-dependent manner. Cycloheximide abolished the HIV-tat-dependent induction of all the adhesion molecules, indicating that protein synthesis was required for induction. The effect of HIV-tat on expression of adhesion molecules was potentiated by tumor necrosis factor (TNF), a well-known inducer of adhesion molecules. Like TNF, HIV-tat also enhanced the adhesion of human promyelomonocytic HL-60 cells to EC, and this effect was abolished by treatment with antibodies either against HIV-tat or adhesion molecules. Our results thus indicate that the HIV-tat protein can activate human vascular EC to induce the expression of various adhesion molecules that may play a role in the extravasation of HIV-infected cells.

Magnetic resonance imaging of the uterus after endometrial resection

OBJECTIVE

Despite the increasing popularity of endometrial resection for the treatment of menstrual problems, the long term sequelae of this procedure are poorly recognised. As diagnostic hysteroscopy following endometrial resection is frequently unrewarding and transvaginal ultrasound is incapable of detecting subtle changes in endometrial morphology, magnetic resonance imaging was employed to evaluate the uterus.

DESIGN

Retrospective study of unselected post-operative women.

METHODS

Fifty-nine women, of whom 22 were amenorrhoeic, were studied a mean number of 34 months after endometrial resection, using a 1.5 Tesla magnetic resonance imaging system with a pelvic phased array coil for signal reception. T2-weighted FSE images were acquired through the long and short uterine axis and volumetric assessment of each uterine layer performed using an ISG Allegro workstation.

MAIN OUTCOME MEASURES

The location and volume of residual endometrium, the volume of junctional zone and myometrial tissue, and the presence of additional intrauterine and pelvic pathology were recorded.

RESULTS

Residual endometrium was demonstrated in all except three amenorrhoeic women, with a similar mean volume present in menstruating and amenorrhoeic groups. Additional findings included adenomyosis, haematometra, fallopian tube dilatation and free intraperitoneal fluid.

CONCLUSIONS

The majority of amenorrhoeic and all menstruating women have residual endometrium after endometrial resection. The lack of communication of islands of residual endometrium with the uterine cavity results in haematometra formation, fallopian tube dilatation and possibly free intraperitoneal fluid.

Reflux oesophagitis in acid peptic disease (a fibre-optic endoscopic study)

This study is based on entry criteria of visual findings of the upper gastro-intestinal fibre-optic endoscopy performed on 100 patients suffering from acid peptic disease (dyspepsia). The diagnostic criteria and grading of reflux oesophagitis advocated by Savary and Miller have been adopted. Reflux oesophagitis was found in 43 cases having grade I oesophagitis in 48.84%, grade II in 32.56%, grade III in 14.00% and grade IV in 4.60% cases. Reflux oesophagitis was associated with hiatus hernia in 23.26%, chronic gastritis in 9.30% of cases. The age varied from 16-80 years with almost equal incidence of male and female, and the severity of the disease increased with the advancement of age. Endoscopy is advised in every case of dyspepsia before any treatment is initiated.

Impaired antigen presentation to CD4+ T-cells by HIV-infected monocytes is related to down-modulation of CD4 expression on helper T-cells: possible involvement of HIV-induced cellular factors

Defective antigen presentation by HIV-infected monocytes is related to severe immune dysfunction in patients with AIDS, although the mechanism by which this process occurs is not well defined. Here we report that reduced capacity by HIV-infected monocytes to stimulate or present antigen to CD4+ T-cells was mediated by cellular factors associated with the plasma membranes of HIV-infected monocytes. In contrast, soluble factors secreted by HIV-infected monocytes had little or no effect on T-cell stimulation. Reduced T-cell stimulation by HIV-infected monocytes was related to down-modulation of CD4 expression on helper T-cells and was not affected by the inclusion of anti-HIV-gpl20 Ab, indicating the involvement of soluble or cell-associated viral envelope protein to be less likely. Exposure of CD4+ T-cells, that had been in co-culture with HIV-infected monocytes, to uninfected monocytes partially restored impaired T-cell stimulation. Thus, for the first time we report that altered capacity of HIV-infected monocytes to stimulate and present antigen to CD4+ T-cells is related to down-modulation of CD4 expression on T-cells, and appears to occur via membrane-associated cellular factors on HIV-infected monocytes.

Hepatic amyloidosis presenting with severe intrahepatic cholestasis

Systemic amyloidosis presenting with jaundice is rare. A case of primary amyloidosis presenting with severe intrahepatic cholestasis is reported. The patient had hepatomegaly, ascites, and a markedly elevated serum alkaline phosphatase level. He had a rapid downhill course resulting in death. Autopsy showed evidence of amyloidosis involving multiple organs, including the liver, kidney, and heart.

HIV-1-Tat protein promotes chemotaxis and invasive behavior by monocytes

Monocytes are susceptible to HIV infection and to activation by a regulatory gene product of the HIV genome, HIV-Tat. Recently, we have demonstrated that treatment with HIV-Tat up-regulates monocyte adhesion to the endothelium and increases metalloproteinase production. in the present study, we have examined the ability of the HIV-Tat protein to alter the migratory and invasive behavior of monocytes. Monocytes pretreated for 24 h with 10 ng/ml HIV-Tat exhibited enhanced migratory behavior compared with untreated monocytes in chemotaxis assays, both in the absence of a chemoattractant as well as in response to FMLP. in addition, HIV-Tat itself induced the migration of both untreated and HIV-Tat pretreated monocytes. Checkerboard analysis showed that monocytes migrated in response to an HIV-Tat concentration gradient, thus confirming the chemotactic characteristics of the HIV-Tat protein. Pretreatment of monocytes with 10 ng/ml HIV-Tat for 24 h also increased their ability to invade reconstituted extracellular membrane (Matrigel)-coated filters by 5-fold in the absence of chemoattractant. The presence of FMLP or HIV-Tat further enhanced invasion by both untreated and HIV-Tat-pretreated monocytes by more than 10-fold. Monocyte invasion was partially inhibited by the inclusion of anti-beta integrin Ab or tissue inhibitor of metalloproteinase (TIMP). Thus, for the first time, we present evidence that HIV-Tat can enhance the chemotactic and invasive behaviors of monocytes and propose an active role for HIV-Tat in the recruitment of monocytes into extravascular tissues, a process which may contribute to the destruction of tissues and cellular architecture often seen in patients with acquired immunodeficiency syndrome.

HIV-1-Tat protein promotes chemotaxis and invasive behavior by monocytes

Monocytes are susceptible to HIV infection and to activation by a regulatory gene product of the HIV genome, HIV-Tat. Recently, we have demonstrated that treatment with HIV-Tat up-regulates monocyte adhesion to the endothelium and increases metalloproteinase production. in the present study, we have examined the ability of the HIV-Tat protein to alter the migratory and invasive behavior of monocytes. Monocytes pretreated for 24 h with 10 ng/ml HIV-Tat exhibited enhanced migratory behavior compared with untreated monocytes in chemotaxis assays, both in the absence of a chemoattractant as well as in response to FMLP. in addition, HIV-Tat itself induced the migration of both untreated and HIV-Tat pretreated monocytes. Checkerboard analysis showed that monocytes migrated in response to an HIV-Tat concentration gradient, thus confirming the chemotactic characteristics of the HIV-Tat protein. Pretreatment of monocytes with 10 ng/ml HIV-Tat for 24 h also increased their ability to invade reconstituted extracellular membrane (Matrigel)-coated filters by 5-fold in the absence of chemoattractant. The presence of FMLP or HIV-Tat further enhanced invasion by both untreated and HIV-Tat-pretreated monocytes by more than 10-fold. Monocyte invasion was partially inhibited by the inclusion of anti-beta integrin Ab or tissue inhibitor of metalloproteinase (TIMP). Thus, for the first time, we present evidence that HIV-Tat can enhance the chemotactic and invasive behaviors of monocytes and propose an active role for HIV-Tat in the recruitment of monocytes into extravascular tissues, a process which may contribute to the destruction of tissues and cellular architecture often seen in patients with acquired immunodeficiency syndrome.

HIV-1-Tat modulates the function of monocytes and alters their interactions with microvessel endothelial cells. A mechanism of HIV pathogenesis

Monocytes are major targets of HIV infection in patients with AIDS. In vitro infection of monocytes with HIV is associated with increased expression of beta 2 integrins, which increases both monocyte aggregation and monocyte/endothelial adhesion as well as monocyte metalloproteinase (MMP-9) expression. Treatment of primary monocytes with soluble HIV-Tat protein mimicked many of the properties of HIV infection of monocytes. Tat treatment up-regulated the expression of the beta 2 integrins, which was associated with the formation of large aggregates of monocytes and increased adhesion to endothelial monolayers. Treatment of monocytes with Tat increased their adhesion to both untreated and TNF-alpha-treated endothelial monolayers, and adhesion was inhibited by inclusion of anti-beta 2 and anti-ICAM-1 Abs. The increased adhesion of activated monocytes was accompanied by substantial disruption of the endothelial monolayers, with retraction or detachment of individual endothelial cells. Tat treatment of monocytes up-regulated the synthesis and release of the protease MMP-9, providing a potential mechanism to explain endothelial cell/basement membrane detachment. Thus, extracellular Tat is capable of activating monocytes even in the absence of HIV infection. Our studies demonstrate that many of the effects of HIV infection on monocyte homotypic and heterotypic adhesion, protease secretion, and disruption of the endothelium can be mimicked by treatment with HIV-Tat protein alone. These results suggest a mechanism where monocytes could be inappropriately activated by HIV-Tat, secreted by HIV-infected cells, causing them to extravasate into underlying tissues and ultimately contribute to tissue damage as seen during the progression of AIDS.

HIV-1-Tat modulates the function of monocytes and alters their interactions with microvessel endothelial cells. A mechanism of HIV pathogenesis

Monocytes are major targets of HIV infection in patients with AIDS. In vitro infection of monocytes with HIV is associated with increased expression of beta 2 integrins, which increases both monocyte aggregation and monocyte/endothelial adhesion as well as monocyte metalloproteinase (MMP-9) expression. Treatment of primary monocytes with soluble HIV-Tat protein mimicked many of the properties of HIV infection of monocytes. Tat treatment up-regulated the expression of the beta 2 integrins, which was associated with the formation of large aggregates of monocytes and increased adhesion to endothelial monolayers. Treatment of monocytes with Tat increased their adhesion to both untreated and TNF-alpha-treated endothelial monolayers, and adhesion was inhibited by inclusion of anti-beta 2 and anti-ICAM-1 Abs. The increased adhesion of activated monocytes was accompanied by substantial disruption of the endothelial monolayers, with retraction or detachment of individual endothelial cells. Tat treatment of monocytes up-regulated the synthesis and release of the protease MMP-9, providing a potential mechanism to explain endothelial cell/basement membrane detachment. Thus, extracellular Tat is capable of activating monocytes even in the absence of HIV infection. Our studies demonstrate that many of the effects of HIV infection on monocyte homotypic and heterotypic adhesion, protease secretion, and disruption of the endothelium can be mimicked by treatment with HIV-Tat protein alone. These results suggest a mechanism where monocytes could be inappropriately activated by HIV-Tat, secreted by HIV-infected cells, causing them to extravasate into underlying tissues and ultimately contribute to tissue damage as seen during the progression of AIDS.

Interferon-gamma inhibits HIV-induced invasiveness of monocytes

HIV-infected monocytes form highly invasive network on basement membrane matrix and secrete high levels of 92-kd metalloproteinase (MMP-9), an enzyme that degrades basement membrane proteins. In the present study, using matrigel as a model basement membrane system, we demonstrate that treatment of human immunodeficiency virus (HIV)-infected monocytes with interferon-gamma at 50 U/ml inhibited the ability of infected monocytes to form an invasive network on matrigel and their invasion through the matrigel matrix. These effects were associated with a significant reduction in the levels of MMP-9 produced by HIV-infected monocytes treated with interferon-gamma 1 day prior to infection with HIV as compared with that of untreated HIV-infected monocytes. Monocytes treated with interferon-gamma 1 day after HIV infection showed the presence of integrated HIV sequences; however, the levels of MMP-9 were substantially lower than those produced by monocytes inoculated with live HIV, heat-inactivated HIV, or even the control uninfected monocytes. Exposure of monocytes to heat-inactivated HIV did not result in increased invasiveness or high MMP-9 production, suggesting that regulation of metalloproteinase by monocytes was independent of CD4-gp120 interactions and required active virus infection. Furthermore, addition of interferon-gamma to monocytes on day 10 after infection inhibited MMP-9 production by more than threefold with no significant reduction of virus replication. These results indicate that the mechanism of interferon-gamma-induced down-regulation of MMP-9 levels and reduced monocyte invasiveness may be mediated by a mechanism independent of antiviral activity of IFN-gamma in monocytes. Down-regulation of MMP-9 in HIV-infected monocytes by interferon-gamma may play an important role in the control of HIV pathogenesis.

Birth weights of infants of first generation Asian women in Britain compared with second generation Asian women

OBJECTIVES

To compare birth weights of infants of first generation Asian women (women born in the Indian subcontinent) with those of infants of second generation Asian women (born in the United Kingdom).

DESIGN

Retrospective case note study.

SETTING

Bolton District General Hospital.

SUBJECTS

331 Asian women who gave birth between January 1989 and December 1989: 220 of these women were first generation Asians and 111 were second generation Asians.

MAIN OUTCOME MEASURE

Birth weights of babies born to first and second generation Asian women.

RESULTS

At all gestational ages at delivery, babies born to second generation Asian women were heavier than those born to first generation women. The mean birth weight for babies of second generation women was 3196 g, 249 g more than the mean birth weight of 2946 g of babies of first generation women (P < 0.001). After a stepwise multiple regression analysis was carried out the adjusted difference in birth weights was 280 g, greater than the crude difference.

CONCLUSION

Birth weights are important in relation to perinatal mortality, which is notoriously high among Asians. The results of this study indicate that there is hope for lowering of perinatal mortality and improving postnatal growth in babies of second generation Asians.

Interferon-gamma-induced downregulation of CD4 inhibits the entry of human immunodeficiency virus type-1 in primary monocytes

We have previously shown that the treatment of monocytes with interferon-gamma (IFN-gamma) prior to exposure with human immunodeficiency virus type-1 (HIV) results in complete inhibition of HIV infection of monocytes. In the present report, we have extended this study to obtain information on the mechanism(s) underlying IFN-gamma-induced inhibition of HIV infection of monocytes. To examine the effect of IFN-gamma on HIV entry, the first event in the infectious cycle of the virus, we amplified HIV-gag sequences in the genomic DNA and RNA of IFN-gamma treated monocytes, and found no evidence for the presence of either proviral DNA or HIV RNA sequences. These results were consistent with the absence of intracellular HIV particles either in the latent or actively replicating state as determined by flow-cytometric analysis of these cells. Furthermore, no HIV-induced cytopathic effects, such as multinucleated giant cell formation or cell death, were observed in IFN-gamma-treated monocytes after their exposure to HIV. Stimulation of IFN-gamma-treated monocytes 6 days postinfection with tumor necrosis factor-alpha (TNF-alpha), which is known to augment HIV replication in the infected cells, did not result in the induction of the HIV indicating the absence of latent HIV infection in IFN-gamma-treated monocytes. Treatment of monocytes with IFN-gamma, TNF-alpha, or with a combination of the two agents which is known to induce antimicrobial free radical nitric oxide (NO2- in the murine system did not induce NO2- production human monocytes suggesting the antiviral activity of IFN-gamma to be independent of NO2(-)-mediated killing of HIV or HIV-infected monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV-1 infection alters monocyte interactions with human microvascular endothelial cells

HIV infection of monocytes resulted in twofold elevation of adhesion molecule LFA-1 (both alpha L/CD11a and beta 2/CD18 subunits) and LFA-3 (CD58), with no apparent increase in LFA-2 (CD2) or various beta 1-integrins. Homotypic aggregation of monocytes was evident 2 h after exposure to virus and was inhibited by mAbs to both the alpha L- and beta 2-subunits of LFA-1. HIV-infected monocytes also showed a marked increase in adherence to human capillary endothelial cell monolayers derived from brain, lung, and skin. This adherence was inhibited by mAb to either LFA-1 subunit and by mAb to the counter-receptor intercellular adhesion molecule-1. Cocultivation of HIV-infected monocytes with endothelial cells increased permeability of endothelial cell monolayers to 125I albumin in transwell assay systems. The increased endothelial permeability induced by HIV-infected monocytes was associated with a substantial disruption of the endothelial cell monolayer. Morphologic disruption was not a direct toxic effect on endothelial cells, but appeared to be secondary to changes in endothelial cell-cell or cell-matrix interactions. Northern blot analysis showed increased expression of gelatinase B (92-kDa gelatinase), tissue inhibitor of metalloproteinase TIMP-1, and TIMP-2 in the HIV-infected monocytes. Consistent with these Northern analyses, secretion of gelatinase activity in culture fluids of HIV-infected monocytes was also increased and was dependent on the stage of virus replication. Incubation of HIV-infected monocytes with the proteinase inhibitors TIMP-1 and TIMP-2 inhibited the increased permeability of endothelial cell monolayers to 125I albumin. These results suggest possible mechanisms for extravasation of HIV-infected monocytes through vascular endothelium into tissue in early stages of HIV disease.