A novel action of minocycline: inhibition of human immunodeficiency virus type 1 infection in microglia

Human immunodeficiency virus type 1 (HIV-1) infection of the brain produces a characteristic disease called acquired immunodeficiency syndrome (AIDS) dementia in which productive infection and inflammatory activation of microglia and macrophages play a central role. In this report, the authors demonstrate that minocycline (MC), a second-generation tetracycline with proven safety and penetration to the central nervous system, potently inhibited viral production from microglia. Inhibition of viral release was sustained through the entire course of infection and even when the drug exposure was limited to the first day of infection. Minocycline was effective even at low viral doses, and against R5- and X4R5-HIV, as well as in single-cycle reporter virus assays. Electrophoretic mobility shift analysis showed that minocycline inhibited nuclear factor (NF)-kappaB activation in microglia. HIV-1 long terminal repeat (LTR)-promoter activity in U38 cells was also inhibited. These results, combined with recently demonstrated in vivo anti-inflammatory effects of MC on microglia, suggest a potential utility for MC as an effective adjunct therapy for AIDS dementia.

Animal models of cancer and HIV

PURPOSE OF REVIEW

The purpose of this paper is to review current animal models that may be useful for studying cancer associated with human immunodeficiency virus infection.

RECENT FINDINGS

Several animal models, primarily using mice and monkeys, have been developed that recapitulate aspects of the pathology of various malignancies in human acquired immune deficiency syndrome. Studies reviewed here help to elucidate the biology of Kaposi sarcomagenesis and non-Hodgkin lymphomagenesis. Improved understanding through current and future models will better enable clinicians to manage and treat these malignancies.

SUMMARY

A number of potential useful models exist that may facilitate improved understanding of the pathogenesis and treatment of cancers associated with human immunodeficiency virus infection.

Purified complexes of HIV-1 envelope glycoproteins with CD4 and CCR5(CXCR4): production, characterization and immunogenicity

The ability to readily elicit broadly neutralizing antibodies to HIV-1 remains elusive. We and others have hypothesized that interaction of the viral envelope glycoprotein (Env, gp120-gp41) with its receptor molecules could enhance the exposure of conserved epitopes that may facilitate the elicitation of broadly neutralizing antibodies. The Env-CD4-coreceptor complexes mediate HIV-1 entry into cells and serve as a major target for inhibitors of this process. To begin to evaluate their potential also as vaccine immunogens we produced relatively large amounts of complexes of purified recombinant soluble truncated Env, gp140(89.6) or gp120(89.6), with CD4 and CCR5 or CXCR4. We found that gp140(gp120)-CD4-CCR5 complexes are stable and immunogenic in mice transgenic for human CD4 and CCR5. They elicited anti-gp120 and anti-gp140 antibodies that inhibited an heterologous primary HIV-1 isolate (JR-FL) with two- to threefold higher neutralizing activity than those elicited by gp120 and gp140. The antibodies elicited by the complexes competed better with the antibodies X5 and CG10 but not with b12 for binding to gp120 and gp120-CD4 complexes compared to those elicited with gp140(120) alone. These findings suggest that stable purified Env-CD4-CCR5(CXCR4) complexes can be produced in relatively large amount sufficient for their further characterization that may help in the development of novel vaccines candidates.

Microglia from mice transgenic for a provirus encoding a monocyte-tropic HIV type 1 isolate produce infectious virus and display in vitro and in vivo upregulation of lipopolysaccharide-induced chemokine gene expression

A large body of evidence has indicated that microglia are the predominant cellular location for HIV-1 in the brains of HIV-1-infected individuals and play a direct role in the development of HIV-1-associated dementia (HAD). Therefore, investigation of the mechanism by which HIV-1-infected microglia contribute to the development of HIV-associated dementia should be facilitated by the creation of a mouse model wherein microglia carry replication-competent HIV-1. To circumvent the inability of HIV-1 to infect mouse cells, we developed a mouse line that is transgenic for a full-length proviral clone of a monocyte-tropic HIV-1 isolate, HIV-1(JR-CSF) (JR-CSF mice), whose T cells and monocytes produce infectious HIV-1. We detected expression of the long terminal repeat-regulated proviral transgene in the microglia of these transgenic mice and demonstrated that it was increased by in vitro and in vivo stimulation with lipopolysaccharide. Furthermore, microglia isolated from JR-CSF mouse brains produced HIV-1 that was infectious in vitro and in vivo. We examined the effect that carriage of the HIV-1 provirus had on chemokine gene regulation in the brains of these mice and demonstrated that MCP-1 gene expression by JR-CSF mouse microglia and brains was more responsive to in vitro and in vivo stimulation with lipopolysaccharide than were microglia and brains from control mice. Thus, this study indicates that the JR-CSF mice may represent a new mouse model to study the effect of HIV-1 replication on microglia function and its contribution to HIV-1-associated neurological disease.

Development of a novel transgenic mouse/SCID-hu mouse system to characterize the in vivo behavior of reservoirs of human immunodeficiency virus type 1-infected cells

To develop a system in which transgenic and knockout technologies are used to study the in vivo behavior of human immunodeficiency virus type 1 (HIV-1) reservoirs, 2 different mouse models were combined: transgenic mice carrying full-length provirus encoding the monocyte-tropic HIV-1(JR-CSF) isolate (JR-CSF mice) and severe combined immunodeficient mice implanted with human fetal thymus and liver tissues (thy/liv-SCID-hu mice). Extensive HIV-1 infection of human thymic implants occurred after injection of JR-CSF mouse leukocytes into thy/liv-SCID-hu mice, indicating that these cells provide an in vivo source of replication-competent HIV-1. In vivo persistence of transferred JR-CSF mouse leukocytes carrying replication-competent HIV-1 in thy/liv-SCID-hu mice was indicated by the emergence of HIV-1 infection in mice that had no detectable HIV-1 infection until after highly active antiretroviral therapy. Thus, thy/liv-SCID-hu mice populated with JR-CSF mouse leukocytes, a persistent cellular reservoir harboring replication-competent HIV-1, present a new in vivo system for characterizing reservoirs of HIV-1 and evaluating therapeutic strategies designed to eliminate them.

Vpr- and Nef-dependent induction of RANTES/CCL5 in microglial cells

Microglia are pivotal in the pathogenesis of AIDS dementia, as they serve as the major target of HIV infection in the CNS. In addition, activation of microglia correlates best with clinical dementia. Although the beta-chemokine RANTES/CCL5 is important in modulating HIV infection as well as cellular activation, no information is available regarding how its expression is regulated in microglia by HIV-1. Here we report that RANTES/CCL5 expression is induced in microglia by HIV-1, but that this requires infection by HIV-1. This conclusion was supported by (1) the delayed kinetics coinciding with viral replication; (2) the lack of effect of X4 viruses; (3) inhibition by the reverse transcriptase inhibitor AZT, and (4) the lack of effect of cytokine antagonists or antibodies. Interestingly, RANTES/CCL5 production was dependent on the viral accessory protein Vpr, in addition to Nef, demonstrating a novel role for Vpr in chemokine induction in primary macrophage-type cells. Furthermore, the specific p38 MAP kinase inhibitor SB203580 augmented chemokine expression in microglia, indicating a negative role played by p38. These data suggest unique features of RANTES/CCL5 regulation by HIV-1 in human microglial cells.

GM-CSF and M-CSF modulate beta-chemokine and HIV-1 expression in microglia

Significant numbers of patients with acquired immunodeficiency syndrome (AIDS) develop CNS infection primarily in macrophages and microglial cells. Therefore, the regulation of human immunodeficiency virus type 1 (HIV-1) infection and activation of the brain mononuclear phagocytes subsequent to infection are important areas of investigation. In the current report, we studied the role of granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage-CSF (M-CSF) in the expression of antiviral beta-chemokines and HIV-1 p24 in cultures of primary human fetal microglia. We found that stimulation with GM-CSF or M-CSF induced macrophage inflammatory proteins (MIP-1alpha and MIP-1beta) and augmented RANTES expression, after HIV-1 infection of microglia. This was not due to the effect of GM-CSF on viral expression because GM-CSF was neither necessary nor stimulatory for viral infection, nor did GM-CSF enhance the expression of env-pseudotyped reporter viruses. Blocking GM-CSF-induced microglial proliferation by nocodazole had no effect on beta-chemokine or p24 expression. The functional significance of the GM-CSF-induced beta-chemokines was suggested by the finding that, in the presence of GM-CSF, exogenous beta-chemokines lost their anti-HIV-1 effects. We further show that although HIV-1-infected microglia produced M-CSF, they failed to produce GM-CSF. In vivo, GM-CSF expression was localized to activated astrocytes and some inflammatory cells in HIV-1 encephalitis, suggesting paracrine activation of microglia through GM-CSF. Our results demonstrate a complex interplay between CSFs, chemokines, and virus in microglial cells and may have bearing on the interpretation of data derived in vivo and in vitro.

Gene therapy using a simian virus 40-derived vector inhibits the development of in vivo human immunodeficiency virus type 1 infection of severe combined immunodeficiency mice implanted with human fetal thymic and liver tissue

To evaluate the in vivo efficacy of gene therapy for treating human immunodeficiency virus type 1 (HIV-1) infection, a novel simian virus (SV) 40-derived vector gene delivery system that efficiently transduces human leukocytes was combined with a model using severe combined immunodeficiency mice infected with HIV-1 and implanted with human fetal thymic and liver tissue (thy/liv-SCID-hu mice). The SV40-derived vector, SV(Aw), which encodes a variable fragment antibody recognizing HIV-1 integrase (IN#33),was injected into the human thymic grafts of thy/liv-SCID-hu mice and induced IN#33 expression in most of the thymocytes in the graft. After in vivo challenge with HIV-1, IN#33 expression inhibited in vivo HIV-1 infection, as evidenced by the markedly lower number of HIV-1-infected thymocytes detected in human thymic grafts injected with the SV(Aw) vector, compared with those injected with a control SV40-derived vector. Thus, these findings demonstrate the utility of this new mouse model system for assessing the in vivo efficacy of HIV-1-specific gene therapy. In addition, these data indicate that SV40-derived vectors may provide a system capable of efficient in vivo gene delivery.

Stromal-derived factor 1 expression in the human thymus

Stromal-derived factor-1 (SDF-1), the only known ligand for the chemokine receptor CXCR4, is broadly expressed in cells of both the immune and central nervous systems, and it can induce the migration of resting leukocytes and hemopoietic progenitors. SDF-1 mRNA was previously detected in human thymus-derived stromal cells, but its role in thymopoiesis was unknown. Here we show that SDF-1 is expressed in medullar epithelial cells forming Hassall's corpuscles (HC). In search of the cell type that may be attracted by SDF-1(+) cells in the medulla, we determined that dendritic cells (DC) could be found in situ in close proximity to SDF-1(+) epithelial cells in HC. In HIV-1-infected SCID-hu thymuses, DC contained apoptotic cells and were located within enlarged HC. It was further demonstrated that uptake of apoptotic thymocytes by immature DC induced an increase in CXCR4 expression and SDF-1-mediated chemotaxis. Our data suggest a role for SDF-1 in the elimination of apoptotic thymocytes.

The relationship of acculturation and gender to attitudes toward counseling in Italian and Greek American college students

This exploratory study examined attitudes toward professional psychological services and help provider characteristics among 232 self-identified Italian and Greek American college students in 3 Northeast colleges. Regarding general attitudes toward psychological services in the Italian American sample, women had a greater recognition of personal need for help and higher confidence in the ability of mental health professionals to meet these needs than did men. With regard to preferred counselor demographic characteristics, regardless of gender, lower acculturated Italian American students had a stronger preference for seeing an ethnically similar counselor. With the Greek American sample, there was an interaction effect between acculturation level and gender on attitudes toward services. Among the higher acculturated Greek students, women were more open regarding their personal concerns than men; however, within the lower acculturated cohort, no gender differences were found. With regard to counselor characteristic variables, and similar to Italian Americans, regardless of gender, lower acculturated Greek Americans had a stronger preference for seeing an ethnically similar counselor to discuss a personal problem. Limitations and implications for further research are noted.

Three strategies for changing attributions about severe mental illness

The effects of three strategies for changing stigmatizing attitudes--education (which replaces myths about mental illness with accurate conceptions), contact (which challenges public attitudes about mental illness through direct interactions with persons who have these disorders), and protest (which seeks to suppress stigmatizing attitudes about mental illness)--were examined on attributions about schizophrenia and other severe mental illnesses. One hundred and fifty-two students at a community college were randomly assigned to one of the three strategies or a control condition. They completed a questionnaire about attributions toward six groups--depression, psychosis, cocaine addiction, mental retardation, cancer, and AIDS--prior to and after completing the assigned condition. As expected, results showed that education had no effect on attributions about physical disabilities but led to improved attributions in all four psychiatric groups. Contact produced positive changes that exceeded education effects in attributions about targeted psychiatric disabilities: depression and psychosis. Protest yielded no significant changes in attributions about any group. This study also examined the effects of these strategies on processing information about mental illness.

Social stories, written text cues, and video feedback: effects on social communication of children with autism

This study investigated the effects of written text and pictorial cuing with supplemental video feedback on the social communication of 5 students with autism and social deficits. Two peers without disabilities participated as social partners with each child with autism to form five triads. Treatment was implemented twice per week and consisted of 10 min of systematic instruction using visual stimuli, 10 min of social interaction, and 10 min of self-evaluation using video feedback. Results showed increases in targeted social communication skills when the treatment was implemented. Some generalized treatment effects were observed across untrained social behaviors, and 1 participant generalized improvements within the classroom. In addition, naive judges reported perceived improvements in the quality of reciprocal interactions. These findings support recommendations for using visually cued instruction to guide the social language development of young children with autism as they interact with peers without disabilities.

A multilevel model framework for meta-analysis of clinical trials with binary outcomes

In this paper we explore the potential of multilevel models for meta-analysis of trials with binary outcomes for both summary data, such as log-odds ratios, and individual patient data. Conventional fixed effect and random effects models are put into a multilevel model framework, which provides maximum likelihood or restricted maximum likelihood estimation. To exemplify the methods, we use the results from 22 trials to prevent respiratory tract infections; we also make comparisons with a second example data set comprising fewer trials. Within summary data methods, confidence intervals for the overall treatment effect and for the between-trial variance may be derived from likelihood based methods or a parametric bootstrap as well as from Wald methods; the bootstrap intervals are preferred because they relax the assumptions required by the other two methods. When modelling individual patient data, a bias corrected bootstrap may be used to provide unbiased estimation and correctly located confidence intervals; this method is particularly valuable for the between-trial variance. The trial effects may be modelled as either fixed or random within individual data models, and we discuss the corresponding assumptions and implications. If random trial effects are used, the covariance between these and the random treatment effects should be included; the resulting model is equivalent to a bivariate approach to meta-analysis. Having implemented these techniques, the flexibility of multilevel modelling may be exploited in facilitating extensions to standard meta-analysis methods.

Suppression of HIV type 1 replication by a dominant-negative Ets-1 mutant

Activity of the distal region of the human immunodeficiency virus (HIV-1) long terminal repeat (LTR), which contains binding sites for the Ets-1 and USF-1 proteins, is integral for HIV-1 replication. The Ets-1 and USF-1 proteins play a critical role in the activity of the HIV-1 LTR distal enhancer region, as indicated by the potent dominant negative effect of a mutant Ets-1 lacking trans-activation domains on the transcriptional activity of the LTR. To determine the biological relevance of the Ets-1 and USF-1 proteins in HIV-1 replication, we examined the effect of expression of the dominant-negative mutant of Ets-1 (dnEts-1) on HIV-1 infection of T cells. We demonstrated that expression of dnEts markedly suppressed HIV-1 infection of a T cell line. This finding indicates that formation of a transcriptionaly active USF-1/Ets-1 complex is important in the productive infection of cells by HIV-1, and suggests that inhibition of the interaction between USF-1 and Ets-1 with the HIV-1 LTR may provide a new target for anti-HIV-1 gene therapy.

Multivariate spatial models for event data

This paper describes how estimates made for event rates in small areas may be enhanced through spatial modelling of the data - taking the geographical location of each area into account - and through the addition of further information from each area. In particular we consider the use of spatial models to predict more than one outcome simultaneously. This is done by writing the spatial model as a multi-level model and subsequently enhancing this to encompass a multivariate data structure; estimates are obtained using iterative generalized least squares in the software package MLwiN. The example given considers mortality due to two causes--neoplasms and circulatory disease--in 143 postcode sectors in Greater Glasgow Health Board, Scotland. In addition, a measure of socio-economic deprivation is available for each area. Correlations between causes within areas, between areas within causes and between areas and causes are quantified, as are the relative contributions of the heterogeneous and spatial parts of the model. The results suggest a tendency for there to be pockets with high mortality rates due to neoplasms, whilst mortality due to circulatory disease follows a much smoother pattern. After taking deprivation into account, the spatial component accounts for just 19 per cent of the variation in the mortality due to neoplasms in Greater Glasgow but 66 per cent of the mortality due to circulatory disease.

Efficient gene transfer to hematopoietic progenitor cells using SV40-derived vectors

We used recombinant SV40 (rSV40)-derived vectors to deliver transgenes to human and simian hematopoietic progenitor cells in culture, and in vivo after transduction ex vivo. rSV40 are highly efficient vectors that are made in very high titers. They infect almost all cells, whether resting or dividing. Two rSV40s were used: SV(HBS), carrying hepatitis B surface antigen as a marker; and SV(Aw) carrying IN#33, a single chain Fv antibody against HIV-1 integrase. CD34+ cells derived from human fetal bone marrow (HFBM) and rhesus macaque bone marrow were transduced once with SV(HBS) without selection. On average 60% of colonies derived from transduced CD34+ cells carried and expressed HBsAg, as assessed by PCR and immunochemistry. Transgene carriage persisted following differentiation of transduced rhesus CD34+ cells into T lymphocytes. In an effort to increase the percentage of gene-marked cells, three sequential treatments of CD34+ cells were done using SV(Aw), without selection. Two weeks later, >95% of colonies expressed IN#33. Unselected SV(Aw)-transduced CD34+ cells from HFBM were transplanted into sublethally irradiated SCID mice. Bone marrow harvested 3 months later showed that >50% of bone marrow cells expressed IN#33. This is comparable with the percentage of human cells in these animals' bone marrow as judged by immunostaining for human CD45. The stability and longevity of transduction in this setting suggests that rSV40 vectors integrate into the cellular genome. This possibility was supported by finding that PCR of genomic DNA using primer pairs with one cellular and one viral primer yielded PCR products only in transduced, but not control, cells. These PCR products hybridized with an SV40 DNA fragment. Thus, rSV40 vectors transduce normal human and primate bone marrow progenitor cells effectively without selection, and maintain transgene expression in vivo following reimplantation. Such high efficiency transduction may be useful in treating diseases of CD34+ cells and their derivatives.

The utility of thyroid nuclear imaging and other studies in the detection and treatment of underlying thyroid abnormalities in patients with endogenous subclinical thyrotoxicosis

PURPOSE

Endogenous subclinical thyrotoxicosis is diagnosed when a patient who is not taking exogenous thyroid hormone has a suppressed level of thyroid-stimulating hormone with normal levels of the free thyroid hormones thyroxine and triiodothyronine and other known causes of a suppressed thyroid-stimulating hormone level have been excluded. Although such a condition is caused by underlying thyroid disease, the specific nature and relative prevalence of these disorders and the utility of nuclear imaging and other studies in their detection remains unclear.

PATIENTS AND METHODS

The authors performed a retrospective study of 50 patients with endogenous subclinical thyrotoxicosis. The results of the history and physical examination, thyroid nuclear scan, radioactive iodine uptake measurement, and thyroid antibody studies were reviewed. The results of the nuclear imaging and thyroid antibody studies were combined in an attempt to establish an underlying diagnosis for each patient.

RESULTS

The thyroid nuclear imaging and antibody studies were used to establish a specific thyroid disorder in most of the patients (n = 39). These disorders included most commonly toxic multinodular goiter, various forms of autoimmune thyroid disease, and solitary toxic adenoma. A specific diagnosis was not determined in 11 patients. Therapy with I-131 radioactive iodine was administered to 14 of these patients, 13 of whom subsequently achieved a normal thyroid-stimulating hormone level.

CONCLUSIONS

Most patients with endogenous subclinical thyrotoxicosis have underlying thyroid abnormalities that can be determined by nuclear imaging and, in selected cases, thyroid antibody studies.

Mice transgenic for monocyte-tropic HIV type 1 produce infectious virus and display plasma viremia: a new in vivo system for studying the postintegration phase of HIV replication

To generate an in vivo system for investigating the postintegration phase of HIV-1 replication, mouse lines transgenic for a full-length infectious proviral clone of a monocyte-tropic HIV-1 isolate, HIV-1JR-CSF, were constructed. Leukocytes from two independent JR-CSF transgenic mouse lines produced HIV-1 that infected human PBMCs. Plasma viremia was detected in these mice at levels (mean, >60,000 HIV RNA copies/ml) comparable to those reported for HIV-1-infected individuals. The levels of HIV RNA in these mice increased several-fold after either treatment with the superantigen Staphylococcus enterotoxin B or infection with Mycobacterium tuberculosis. Thus, a provirus encoding a monocyte-tropic HIV-1 strain under the control of its LTR expressed as a transgene in mice can proceed through the postintegration replication phase and produce infectious virus. In addition, the presence of plasma viremia that can be monitored by measuring plasma HIV-1 RNA levels permits these mice to be used to study the impact of different interventions on modulating in vivo HIV-1 production. Therefore, these mice provide a novel manipulable system to investigate the in vivo regulation of HIV-1 production by factors that activate the immune system. Furthermore, this murine system should be useful in delineating the role of human-specific factors in modulating HIV-1 replication and investigating the in vivo therapeutic efficacy of agents that target the postintegration stages of HIV-1 replication.

Chimeric toxins targeted to the human immunodeficiency virus type 1 envelope glycoprotein augment the in vivo activity of combination antiretroviral therapy in thy/liv-SCID-Hu mice

Highly active antiretroviral therapy (HAART), which combines multiple inhibitors of essential human immunodeficiency virus type 1 (HIV-1) enzymes, induces dramatic and sustained viral load reductions in many people infected with HIV-1. However, reservoirs of infected cells capable of producing replication-competent virus persist even after years of HAART, preventing elimination of infection. CD4-PE40 and 3B3(Fv)-PE38, chimeric toxins designed to target the HIV envelope (Env), represent a complementary class of agents that selectively kill productively infected cells. To investigate whether these Env-targeted toxins might serve as adjuncts to HAART for the elimination of infected cells, we tested their ability to augment HAART efficacy in vivo by using a thy/liv SCID-hu mouse model. CD4-PE40 and 3B3(Fv)-PE38 markedly enhanced the capacity of HAART to suppress acute HIV-1 infection and improved HAART-mediated viral load reduction in mice with established HIV-1 infection. These results represent the first demonstration of in vivo anti-HIV-1 efficacy for Env-targeted toxins and support their potential therapeutic utility in combination with HAART.