Perspectives in HIV pathogenesis, treatment, and prevention.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
J Rappaport
Publications and source records attributed to J Rappaport.
Validation of genetic case-control studies in AIDS and application to the CX3CR1 polymorphism.
New polymorphisms have been recently identified in CX3CR1, a coreceptor for some HIV-1 strains, one of which was associated with a strong acceleration of HIV disease progression. This effect was observed both by a case-control study involving 63 nonprogressors (NP) from the asymptomatic long-term (ALT) cohort and Kaplan-Meier analysis of 426 French seroconverters (SEROCO cohort). These results prompted us to analyze these polymorphisms in 244 nonprogressors (NPs) and 80 rapid progressors (RPs) from the largest case-control cohort known to date, the GRIV cohort. Surprisingly, the genetic frequencies found were identical for both groups under all genetic models (p >.8). The discrepancy with the previous work stemmed only from the difference between GRIV NPs versus ALT NPs. We hypothesized this might be due to the limited number of NPs in ALT (n = 63) and in this line we reanalyzed the data previously collected on GRIV for over 100 different genetic polymorphisms: we effectively observed that the genetic frequencies of some polymorphisms could vary by as much as 10% (absolute percentage) when computing them on the first 50 NP subjects enrolled, on the first 100, or on all the NPs tested (240 study subjects). This observation emphasizes the need for caution in case-control studies involving small numbers of subjects: p values should be low or other control groups should be used.However, the association of the CX3CR1 polymorphism with progression seems quite significant in the Kaplan-Meier analysis of the SEROCO cohort (426 individuals), and the difference observed with GRIV might be explained by a delayed effect of the polymorphism on disease. Further studies on other seroconverter cohorts are needed to confirm the reported association with disease progression.
CX3C Chemokine Receptor 1↗
Autoantibodies to TNFalpha in HIV-1 infection: prospects for anti-cytokine vaccine therapy.
Tumor necrosis factor alpha (TNFalpha) is a proinflammatory cytokine principally involved in the activation of lymphocytes in response to viral infection. TNFalpha also stimulates the production of other cytokines, activates NK cells and potentiates cell death and/or lysis in certain models of viral infection. Although TNFalpha might be expected to be a protective component of an antiviral immune response, several lines of evidence suggest that TNFalpha and other virally-induced cytokines actually may contribute to the pathogenesis of HIV infection. Based on the activation of HIV replication in response to TNFalpha, HIV appears to have evolved to take advantage of host cytokine activation pathways. Antibodies to TNFalpha are present in the serum of normal individuals as well as in certain autoimmune disorders, and may modulate disease progression in the setting of HIV infection. We examined TNFalpha-specific antibodies in HIV-infected non-progressors and healthy seronegatives; anti-TNFalpha antibody levels are significantly higher in GRIV seropositive slow/non-progressors (N = 120, mean = 0.24), compared to seronegative controls (N= 12, mean = 0.11). TNFalpha antibodies correlated positively with viral load, (P = 0.013, r = 0.282), and CD8+ cell count (P = 0.03, r = 0.258), and inversely with CD4+ cell count (P = 0.003, r = - 0.246), percent CD4+ cells (P = 0.008, r = -0.306), and CD4 :CD8 ratio (P = 0.033, r = - 0.251). TNFalpha antibodies also correlated positively with antibodies to peptides corresponding to the CD4 binding site of gp160 (P = 0.001, r = 0.384), the CD4 identity region (P = 0.016, r = 0.29), the V3 loop (P = 0.005, r = 0.34), and the amino terminus of Tat (P = 0.001, r = 0.395); TNFalpha antibodies also correlated positively with antibodies to Nef protein (P = 0.008, r = 0.302). The production of anti-TNFalpha antibodies appears to be an adaptive response to HIV infection and suggests the potential utility of modified cytokine vaccines in the treatment of HIV infections as well as AIDS-related and unrelated autoimmune and CNS disorders.
AIDS Vaccines↗
CNS invasion by CD14+/CD16+ peripheral blood-derived monocytes in HIV dementia: perivascular accumulation and reservoir of HIV infection.
Increases in circulating CD14+/CD16+ monocytes have been associated with HIV dementia; trafficking of these cells into the CNS has been proposed to play an important role in the pathogenesis of HIV-induced neurological disorders. This model suggests that events outside the CNS leading to monocyte activation initiate the process leading to HIV dementia. To investigate the role of this activated monocyte subset in the pathogenesis of HIV dementia, we examined brain specimens from patients with HIV encephalopathy (HIVE), HIV without encephalopathy, and seronegative controls. An accumulation of perivascular macrophages was observed in HIVE. The majority of these cells identified in microglial nodules and in the perivascular infiltrate were CD14+/CD16+. P24 antigen colocalized with both CD14 and CD16 suggesting that the CD14+/CD16+ macrophage is a major reservoir of HIV-1 infection in CNS. Using CD45/LCA staining, the perivascular macrophage was distinguished from resident microglia. In addition to perivascular and nodular localizations, CD16 also stained ramified cells throughout the white matter. These cells were more ramified and abundant than cells positive for CD14 in white matter. Double staining for p24 and CD16 suggests that these cells were often infected with HIV-1. The prominent distribution of CD14+ cells in HIVE prompted our analysis of soluble CD14 levels in cerebrospinal fluid. Higher levels of soluble CD14 (sCD14) were observed in patients with moderate-to-severe HIV dementia, suggesting the utility of sCD14 as a surrogate marker. CD14+/CD16+ monocytes may play a role in other neurological disorders and sCD14 may be useful for evaluating these conditions.
AIDS Dementia Complex↗
Clinical applications of a finite-element model of the human middle ear.
Computer-generated models are increasingly being used in otolaryngology for teaching purposes, preoperative planning, and clinical simulations, especially when dealing with small, complex areas such as the middle ear. One technique used to analyze the mechanics of complex models is the finite-element method, whereby the system of interest is divided into a large number of small, simple elements. The mechanical properties and applied forces are represented by functions defined over each element, and the mechanical response of the whole system can then be computed. We present a unique three-dimensional finite-element model of the human eardrum and middle ear. Our model takes advantage of phase-shift moiré shape measurements to precisely define the shape of the eardrum. The middle ear geometry is derived from histologic serial sections and from high-resolution magnetic resonance microscopy of the human ear. We discuss the importance of this model in terms of understanding and teaching the mechanics of the human middle ear, simulating various pathologic conditions, and designing ossicular prostheses.
Computer Simulation↗
Analysis of telomere length and thymic output in fast and slow/non-progressors with HIV infection.
There are two models for CD4+ T-cell depletion leading to AIDS: a kinetic model and an immune suppression model. In the kinetic model, direct cell killing due to viral replication results in a continuous demand for CD4+ T-cells, which eventually exhausts their capacity for renewal by proliferative mechanisms. In the immune suppression model, CD4+ T-cell decline is due to an indirect global inhibitory effect of the virus on uninfected immune cell function. In order to address differences in the two models, we investigated proliferative history and thymic output in PBMC from the GRIV cohort of fast (FP) and slow/non-progressors (S/NP), and uninfected controls. Proliferative history and thymic output were assessed by measurement of mean telomeric restriction fragment (TRF) length and T-cell receptor Rearrangement Excision Circles (TREC) levels, respectively. Mean TRF lengths were significantly shorter in S/NP (n = 93, 7.59 +/- 0.11 kb) and FP (n = 42, 7.25 +/- 0.15 kb) compared to controls (n = 35, 9.17 +/- 0.19 kb). Mean TRF length in PBMC (n = 9, 7.32 +/- 0.31 kb) and CD4+ enriched fractions (n = 9, 7.41 +/- 0.30 kb) from a subset of non-GRIV HIV-1 infected samples were also significantly smaller than PBMC (n = 8, 9.77 +/- 0.33 kb) and CD4+ fractions (n = 8, 9.41 +/- 0.32 kb) from uninfected controls. Rates of telomeric shortening, however, were similar among S/NP (n = 93, -45 +/- 20 bp/yr), FP (n = 42, -41 +/- 14 bp/yr) and controls (-29 +/- 17 bp/yr). Paralleling differences observed in mean TRF length, TREC levels were significantly reduced in S/NP (n = 10, 3,433 +/- 843 mol/mu and FP (n = 8, 1,193 +/- 413) compared to controls (n = 15, 22,706 +/- 5,089), indicative of a defect in thymopoiesis in HIV-1 infection. When evaluated in the context of reduced thymopoiesis, the difference in mean TRF length between S/NP and controls (1.58 +/- 0.30 kb) is similar to that observed between memory and naïve T-cells (1.4 +/- 0.1 kb), and may reflect perturbations in the peripheral T-cell population due to a decline in thymic output of naïve T-cells rather than increased turnover. Based on the different clinical criteria used to select S/NP and FP, the sight difference in TREC between these two groups suggests the threshold for pathogenesis as a result of naïve T-cell depletion may be quite low, and incremental increases in thymic output may yield substantial clinical results. Future studies regarding therapeutic vaccination, specifically with HIV-1 Tat targeted anti-immunosuppressive vaccines, should address the defect in thymic output in HIV-1 infection by using TREC analysis as a rapid method for biological evaluation.
Acquired Immunodeficiency Syndrome↗
1999 Seymour B. Sarason Award. Community narratives: tales of terror and joy.
Inspired by a literary-feminist reading of biblical texts, it is suggested that the mission of community psychology/social science can be understood as a calling to use our tools (research methods, critical analysis and observation, scholarship, social influence) to assist others in the job of turning tales of terror into tales of joy. Such work is the essence of personal and social change. These are not things we can do alone; they require collaboration between us and the people of concern. Applying concepts from narrative theory, including description and critical analysis of community and setting narratives, dominant cultural narratives, and personal stories, we can learn from our own communities and we can use our resources to help make known (perhaps even help to imagine new) tales of joy. Some of these themes are illustrated in three very different contexts: a religious community that has made itself inclusive of gay and lesbian people, a mutual help organization that offers a sense of community and hope for the future to people with a history of serious mental illness, and a public elementary school.
Black or African American↗
Transdominant activity of human immunodeficiency virus type 1 Vpr with a mutation at residue R73.
The 96-amino-acid-long human immunodeficiency virus type 1 virion-encoded accessory protein Vpr is of particular interest, as this protein, which is found in association with viral particles, can exert a regulatory effect on both virus replication and host cell function. Evidently, Vpr, through interaction with several host regulatory proteins, can modulate transcription from the viral long terminal repeat promoter. Expression of Vpr in cells results in deregulation of cell proliferation during the cell cycle pathway at the G(2) stage. Vpr has unique structural features consisting of multiple functional domains. In this study, we have focused on the leucine/isoleucine-rich domain near the carboxyl terminus of Vpr at residue 73 (arginine) and have demonstrated that alterations at this residue result in ablation of transcriptional activity of Vpr and its ability to block cell cycle events at the G(2) stage. Interestingly, substitution mutations at R73 have resulted in a peptide with dominant negative activities on wild-type functions in transcription and host proliferation events. Results from in vitro and in vivo protein-protein interaction studies have revealed that functionally inactive mutant Vpr can be associated with wild-type protein, presumably through the N-terminal regions of the protein which have been shown to be important for Vpr oligomerization. Thus, it is likely that complexation of the mutant Vpr with wild-type protein functionally inactivates Vpr. The importance of these findings in light of the development of therapeutic strategies is discussed.
Arginine↗
Detection of HIV-1 Tat and JCV capsid protein, VP1, in AIDS brain with progressive multifocal leukoencephalopathy.
HIV-1 infection can lead to severe central nervous system (CNS) clinical syndromes in more than 50% of HIV-1 positive individuals. Progressive multifocal leukoencephalopathy (PML) is the frequent opportunistic infection of the CNS which is seen in as high as 5% of AIDS patients. Results from previous cell culture studies showed that the HIV-1 regulatory protein, Tat can potentiate transcription of the human neurotropic virus, JCV, the causative agent for PML in cells derived from the human CNS. In this communication we examine the presence of the HIV-1 regulatory protein, Tat, as well as the HIV-1 and JCV structural proteins, p24 and VP1, respectively in AIDS/PML clinical samples. We demonstrate high level expression of the JCV capsid protein, VP1, in oligodendrocytes and to some degree in astrocytes of AIDS with PML. In HIV-1+ samples expression of HIV-1 core protein, p24 was detected in perivascular monocytic cells and to a lesser extent in astrocytes and endothelial cells. A lack of p24 expression in oligodendrocytes suggested no infection of these cells with HIV-1. Interestingly, HIV-1 Tat was detected in various infected cells as well as in uninfected oligodendrocytes from HIV-1+ tissue, supporting the earlier in vitro findings that secreted Tat from the infected cells can be localized in the neighboring uninfected cells. The presence of Tat in oligodendrocytes was particularly interesting as this protein can up-modulate JCV gene transcription and several key cell cycle regulatory proteins including cyclin E, Cdk2, and pRb. The data presented here provide in vivo evidence for a role of HIV-1 Tat in the pathogenesis of AIDS/PML by acting as a positive regulatory protein that affects the expression of JCV and other cell regulatory proteins in the CNS.
Acquired Immunodeficiency Syndrome↗
Association of HIV-1 Tat with the cellular protein, Puralpha, is mediated by RNA.
The interaction between two regulatory proteins plays a crucial role in the control of several biological events, including gene transcription. In this report, we demonstrate that the interaction between the cellular sequence-specific single-stranded DNA binding protein Puralpha and the HIV type 1 (HIV-1) Tat protein is mediated by specific ribonucleic acids. The region of Tat that is important for its interaction with Puralpha includes the region demonstrated to bind Tat's viral RNA target, TAR. A 10-nucleotide GC-rich consensus sequence identified in RNAs associated with Puralpha derived from human U-87MG cells plays an important role in the Puralpha:Tat interaction as examined by an in vitro reconstitution assay. Furthermore, expression of the Puralpha-associated RNA in these cells enhances transcriptional activation of the HIV-1 promoter by Tat and Puralpha.
Cyclic AMP Response Element-Binding Protein↗
New class I and II HLA alleles strongly associated with opposite patterns of progression to AIDS.
The genetics of resistance to infection by HIV-1 cohort consists of 200 slow and 75 rapid progressors to AIDS corresponding to the extremes of HIV disease outcome of 20,000 Caucasians of European descent. A comprehensive analysis of HLA class I and class II genes in this highly informative cohort has identified HLA alleles associated with fast or slow progression, including several not described previously. A quantitative analysis shows an overall HLA influence independent of and equal in magnitude (for the protective effect) to the effect of the CCR5-Delta32 mutation. Among HLA class I genes, A29 (p = 0.001) and B22 (p < 0.0001) are significantly associated with rapid progression, whereas B14 (p = 0.001) and C8 (p = 0.004) are significantly associated with nonprogression. The class I alleles B27, B57, C14 (protective), and C16, as well as B35 (susceptible), are also influential, but their effects are less robust. Influence of class II alleles was only observed for DR11. These results confirm the influence of the immune system on disease progression and may have implications on peptide-based vaccine development.
Acquired Immunodeficiency Syndrome↗
Tat toxoid as a component of a preventive vaccine in seronegative subjects.
Because administration of Tat protein, the HIV-1 toxin that induces immunosuppression and apoptosis, may be deleterious to the host immune system, a chemically inactivated but nonetheless immunogenic Tat preparation, Tat toxoid, was used to immunize seronegative individuals against Tat. In an open, controlled, phase I clinical trial, Tat toxoid turned out to be safe, well tolerated, and able to trigger a specific immune reaction. In particular, a threefold to more than 10-fold increase of circulating antibodies directed against the native Tat was observed after immunization in all of 5 immunized study subjects, together with a positive reaction to delayed-type hypersensitivity (DTH) skin test with Tat toxoid in vivo and increased lymphoproliferative response to native Tat in vitro. Persistent (> or =1 year) high levels of circulating anti-Tat antibodies could prevent the Tat-induced immune suppression and, following HIV-1 exposure, allow the anti-HIV-1 cellular immune response, with its early release of protective beta-chemokines, to occur leading to an increase of host resistance, that is, protection.
AIDS Vaccines↗
Molecular pathway involved in HIV-1-induced CNS pathology: role of viral regulatory protein, Tat.
The broad range of histological lesions associated with HIV-1 are somewhat subtle relative to the clinical manifestations that occur as a result of HIV infection. Although it is clear that HIV has a causative role in CNS disease, dementia appears to be a consequence of the infiltration of inflammatory cells and cytokine dysregulation rather than the amount of virus in CNS. The HIV transregulatory protein Tat plays an important intracellular as well as extracellular role in the dysregulation of cytokines. The cytokines and possibly chemokines that are induced by Tat modify the action of astrocytes such that the survival of neurons is compromised. Pathogenetic alteration induced by Tat involves a series of interactions between circulating monocyte/macrophages, endothelial cells, and astrocytes. Cytokine dysregulation induced by viral infection and extracellular Tat leads to alterations in expression of adhesion molecules and promotes migration of non-infected inflammatory cells into the CNS compartment. We demonstrate here that recombinant HIV-1 Tat protein introduced by stereotaxic injection into mouse brain can induce pathologically relevant alterations including macrophage invasion as well as astrocytosis. The mechanism of destruction of the CNS by Tat appears to involve autocrine and paracrine pathways that depend not only on Tat, but cytokine and chemokine signaling pathways that are altered by viral infection. In this review, we discuss various pathogenic effects of Tat in brain cells and provide experimental evidence for an increased TNF-alpha level in CSF in mice injected intracerebrally with Tat protein.
Animals↗
Giving and receiving help: interpersonal transactions in mutual-help meetings and psychosocial adjustment of members.
The helping transactions that occur in group meetings have been theorized to be important therapeutic mechanisms within mutual-help (or self-help) groups. Hypothesized links between giving and receiving help and psychosocial adjustment were examined in a mutual-help group for individuals with serious mental illness (GROW). Participants' adjustment was assessed at two time points and helping behaviors were measured with observational coding of weekly group interactions during the period between assessments. Frequencies of helping behaviors were used to predict Time 2 adjustment after controlling for initial adjustment. Consistent with the helper therapy principle, giving help to others predicted improvements in psychosocial adjustment; giving advice was a unique predictor. Total amount of help received was not associated with adjustment, but receiving help that provided cognitive reframing was associated with better social adjustment. A predicted interaction suggested that receiving help was related to better functioning when members experienced high levels of group integration.
Adaptation, Psychological↗
Professional appraisal of professionally led and self-help groups.
A survey of almost 1,100 mental health professionals found they routinely viewed professionally led groups more positively than they did self-help groups on a number of dimensions. Analyses suggested that the curative factor associated with professionally led groups was valued over factors associated with self-help groups. The implications of the findings are discussed, and an alternative framework for professionals' evaluation of consumer-initiated interventions suggested.
Humans↗
Suppression of HIV-1 transcription and replication by a Vpr mutant.
Vpr, the 96 amino acid long protein represents one of the auxiliary proteins of human immunodeficiency virus type-1 (HIV-1), which exhibits the ability to increase the rate of replication of the virus in T cells. Structurally, this protein is composed of several regions such as the acidic domain with alpha helix at the amino terminus, leucine-isoleucine-rich domain (LR) near the carboxyl terminus and an arginine-rich domain at the C-terminus. Here, we evaluated the ability of wild-type and a spectrum of Vpr mutants with altered amino acid residues within the three major domains of Vpr to regulate of transcription of the HIV-1 LTR. Our results revealed that alterations of amino acids within the LR domain at position 73 from arginine to serine, renders Vpr defective in stimulating transcription of the viral promoter in human T-lymphocytic and astrocytic cells. Mutations within the N- and C-terminal domains had little or no effect on the transcriptional activity of Vpr. Of interest, ectopic expression of this mutant protein exerts a negative effect on the ability of wild-type Vpr, as well as the viral transactivator, Tat, in augmenting viral gene transcription. Production of the mutant Vpr interferes with the replication of the wild-type and delta Vpr virus in the cells. Accordingly, a Vpr mutant virus containing the transition of arginine to serine at position 73 exhibited an inhibitory effect on the replication of wild-type virus. Our results provide a new avenue for the utilization of the variant of the HIV-1 regulatory protein, Vpr, in suppressing replication of the viral genome in infected cells.
Amino Acid Substitution↗
The sCYMV1 hairpin ribozyme: targeting rules and cleavage of heterologous RNA.
The catalytic center of the RNA from the negative strand of the satellite RNA of chicory yellow mottle virus type 1 (sCYMV1) is in the hairpin ribozyme family, has catalytic activity, and cleaves substrates before a preferred GUA sequence. This is different from that of the satellite RNA from the negative strand of tobacco ringspot virus (sTRSV) which prefers a GUC sequence at the site of cleavage. The sCYMV1 hairpin ribozyme has now been developed for cleaving heterologous RNA substrates. When helix 1 was extended from the native 5 bp to 6 bp with a newly added A:U base pair, catalytic activity increased three-fold. The preferred sequence for the substrate loop was the native A*GUA sequence where * is the site of cleavage. When each nucleotide in this sequence was changed to each of the other three nucleotides, catalytic activity decreased 66-100%. RNA targets, containing this A*GUA sequence, were located in both human papillomavirus and HIV-1. Ribozymes were developed which efficiently cleaved these targets in vitro. These results identify a new class of hairpin ribozymes capable of cleaving substrates before a preferred GUA sequence rather than the GUC preferred by the sTRSV hairpin ribozyme. This expands the repertoire of target sites available for gene therapy using the hairpin ribozyme.
Gene Targeting↗
Role of HIV-1 Tat and CC chemokine MIP-1alpha in the pathogenesis of HIV associated central nervous system disorders.
Two syndromes affecting cognitive and motor function in the setting of AIDS have been described as HIV encephalopathy (HIVE) and progressive multifocal leukoencephalopathy (PML). HIVE is characterized by the presence of microglial nodules with accompanying astrocytosis. PML is a fatal demyelinating disease of the white matter induced by the human papovavirus JCV which causes cytolytic destruction of glial cells. In addition to the effect of HIV-1 induced immune suppression, HIV may act directly as a co-factor for stimulation of JCV replication in AIDS patients, in part due to Tat-induced activation of JCV gene transcription. Since Tat has been implicated in CNS pathogenesis, we examined its localization in CNS specimens from HIV infected patients with HIVE and PML as well as controls. Based on the observation of CC chemokine induction in monocytes by Tat, we also examined the cellular localization of the CC chemokine Macrophage Inflammatory Protein-1alpha (MIP-1alpha) and its cognate receptor CCR-5 in these samples. In HIVE, Tat was primarily localized in astrocytes and microglia, within the nodular lesions. In PML, a marked increase in the number of Tat positive astrocytes was observed. In both HIVE and PML, prominent expression of MIP-1alpha and CCR-5 was found within areas containing histopathological lesions. CCR-5 positivity of microglia was localized primarily to nodular lesions in HIVE. In PML, increased numbers of cells with monocyte/microglial morphology were observed relative to HIVE. The increased MIP-1 alpha positivity, and potentially other chemokines, may contribute to the pathogenesis of PML in the setting of HIV infection. Tat may play an important role in the pathogenesis of both HIV associated CNS disease states, acting indirectly through cytokine and chemokine dysregulation.
AIDS Dementia Complex↗