Isolation of HTLV-III from cerebrospinal fluid and neural tissues of patients with neurologic syndromes related to the acquired immunodeficiency syndrome

Controlling Neuropathic Pain in HIV

Neuropathic pain is associated with numerous systemic illnesses, including HIV infection. The diagnosis and management of peripheral neuropathy presents diagnostic and therapeutic challenges. Among various forms of HIV-associated peripheral neuropathies, distal symmetrical polyneuropathy (DSP) is the most common. DSP may be caused or exacerbated by neurotoxic antiretrovirals, particularly the dideoxynucleoside analogues (d-drugs). Selection of appropriate pharmacologic intervention for peripheral neuropathy should be based on efficacy, safety, ease of administration, and cost. We review treatment options for painful HIV neuropathy, including experimental agents studied in recent and ongoing clinical trials.

Cochlear Implantation in Human Immunodeficiency Virus–Infected Patients

OBJECTIVE

To evaluate the efficacy of cochlear implants in human immunodeficiency virus-infected individuals and correlate these results with a proposed pathophysiological mechanism of human immunodeficiency virus-associated hearing loss.

STUDY DESIGN

Retrospective case series and temporal bone analysis of deceased human immunodeficiency virus-positive patients.

SETTING

Tertiary care hospital.

PATIENTS

Seven human immunodeficiency virus-positive individuals with profound sensorineural hearing loss.

INTERVENTION

Cochlear implantation at New York University Medical Center.

METHODS

The surgical outcomes and complications were analyzed. Additionally, electron microscopic and immunohistochemical findings of cadaver temporal bone specimens of other known human immunodeficiency virus-positive individuals were reviewed. The performance results of the human immunodeficiency virus-positive cochlear implant patients were then correlated with the previously hypothesized pathophysiological mechanism of human immunodeficiency virus-associated hearing loss.

RESULTS

The patients had a varied performance with cochlear implantation, and as a group performance was good. There were no surgical complications or postoperative complications. The good performance of these patients supports the hypothesis that the mechanism of human immunodeficiency virus-associated deafness involves infiltration, malfunction, and premature degeneration of the hair cells and supportive cells of the cochlea.

CONCLUSIONS

Human immunodeficiency virus-positive individuals benefit from cochlear implantation without increased surgical risk.

Human blood-derived macrophages enhance barrier function of cultured primary bovine and human brain capillary endothelial cells

The characteristic properties of the blood-brain barrier (BBB) forming brain capillary endothelial cells (BCEC) are modulated by their microenvironment, but the cellular sources of the induction signals are still unclear. Apart from astrocytes, another cell type in close contact with cerebral blood vessels is the perivascular macrophages, which are known to be regularly replaced by blood-derived monocytic precursor cells. It is unknown if, and how, these cells may interact with the cerebral endothelium and modulate its BBB-specific functions. In the present study, a cell culture model of the BBB was used to investigate the effect of blood-derived human macrophages on the permeability of cultured bovine and human BCEC, determined by a transendothelial electrical resistance (TEER) measurement. We found that the TEER of postconfluent BCEC was considerably increased by a non-contact coculture with macrophages. After 24 h, we found a TEER augmentation of over 50% compared with the control without coculture, and this effect was comparable to the response of BCEC to a C6 glioma cells coculture. Stimulation or HIV-1 infection of the macrophages did not alter their effect on BCEC monolayer permeability. Investigation of signal transduction pathways showed that TEER increase of BCEC due to macrophage coculture was cAMP-independent and involves neither phospholipase C, protein kinase C nor calmodulin. Our findings demonstrate that macrophages are able to modulate BBB-specific functions in cultured BCEC. Thus, these cells or cerebral cells of monocytic origin (e.g. perivascular macrophages), may be part of the microenvironment of BCEC that modulates their specific properties in vivo.

[Cerebrospinal fluid parameters in various stages of HIV infection. Results of cross-sectional and longitudinal analysis]

In up to 50% of all human immunodeficiency virus (HIV) patients, the nervous system is clinically involved. Primary or secondary manifestations of the nervous system have been found in even 90% by neuropathological investigations. We present a retrospective analysis of cerebrospinal fluid (CSF) and serum data of 238 HIV patients. Data of cross-sectional analysis in 208 patients and longitudinal analysis in 30 patients are given. In addition, the viral load in CSF and serum was determined in 29 patients. The HIV patients without opportunistic infections showed increased levels of immunoglobulins and more oligoclonal bands. In later stages of the infection, beta-2 microglobulin as a marker of HIV-associated encephalopathy was increased. In the longitudinal study with an observation period of 1 year, an increase could be observed in total CSF proteins of patients who did not receive antiretroviral treatment. In patients with new opportunistic infections of the central nervous system, similar changes in CSF parameters were noted as in comparison to patients not infected by HIV but with the same opportunistic infections. Analysis of CSF is mandatory for the diagnosis and control of opportunistic infections.

Influence of depressed mood on neuropsychologic performance in HIV-seropositive drug users

Some studies point out that depression affects the performance of HIV patients in neuropsychological tasks, but at present this effect is not clear. The purpose of the present paper was to study whether the presence of symptoms of depression affects the neuropsychologic performance of seropositive drug users in tasks of attention/concentration, learning and memory, language, construction and visuospatial function, speed of motor performance, cognitive flexibility, manual skill and concept formation and reasoning. In order to carry out this research a sample consisting of 127 male volunteer subjects was used. These subjects were distributed in four groups: one group consisted of HIV-seropositive drug users with symptoms of depression (n = 33); the second group consisted of HIV-seropositive drug users without symptoms of depression (n = 47); the third group was formed by HIV-seronegative drug users with symptoms of depression (n = 15) and the fourth group was formed by HIV-seronegative drug users without symptoms of depression (n = 32). The results reveal the effect of symptoms of depression (evaluated by the Beck Depression Inventory) on the neuropsychologic performance of seropositive drug users. This effect, however, was not observed in the seronegative group. These findings lead us to suggest that symptoms of depression constitute a risk factor for presenting neuropsychologic disturbances in seropositive subjects, which could well be acting as a factor that foments the neuropsychological effects of HIV.

Health and safety at necropsy

The postmortem room is a source of potential hazards and risks, not only to the pathologist and anatomical pathology technician, but also to visitors to the mortuary and those handling the body after necropsy. Postmortem staff have a legal responsibility to make themselves aware of, and to minimise, these dangers. This review focuses specifically on those hazards and risks associated with the necropsy of infected patients, with foreign objects present in the body, and with bodies that have been contaminated by chemicals or radioactive sources.

Nucleoside analogues and neuropathy in the era of HAART

BACKGROUND

Sensory neuropathies occur commonly in the setting of HIV infection. Sensory neuropathy (SN) is clearly associated with HIV itself, and in this context develops in association with increased macrophage activation in the peripheral nervous system. A clinically identical SN may also occur as a consequence of exposure to some HIV treatments. In this setting, impaired mitochondrial function is thought to play a role in the development of neurological dysfunction.

OBJECTIVE

This review explores the evidence for the neurotoxicity of HIV and HIV treatments, the effect of nucleoside reverse transcriptase inhibitors on mitochondria, and the likely associations between these.

CONCLUSIONS

Dideoxynucleotide drugs are commonly associated with SN. The nucleoside reverse transcriptase inhibitors inhibit mitochondrial DNA synthesis and may thus exacerbate existing viral-induced nerve damage.

Intraocular and plasma HIV-1 RNA in HIV-infected patients with CMV retinitis and HIV-infected controls

HIV-1 RNA was quantified in intraocular specimens and plasma from AIDS patients with CMV retinitis undergoing therapeutic vitrectomy and in 8 control subjects undergoing cataract surgery using the Amplicor RT-PCR-based assay. The HIV-1 RNA concentration in the intraocular specimens was significantly lower than in plasma. Patients with CMV retinitis and plasma HIV-1 RNA concentrations > 100,000 copies/ml generally had detectable HIV-1 RNA in their intraocular specimens. These findings point to the risk of percutaneous injury from a sharp instrument used in HIV-infected patients during ophthalmic surgery and possible transmission of HIV during such surgery. Prevention of percutaneous contact will require the use of surgical instruments that reduce the likelihood of injury, as well as the wearing of double gloves during surgery.

HIV-1 infection and AIDS

Since the initial descriptions of AIDS in the late 1970s, much has been learned about the biology of HIV-1 and the cells it infects. Much has also been learned about mother-to-infant viral transmission and the natural history of HIV-1 infection. Key studies led to strategies for interrupting mother-to-infant transmission, resulting in a significant decline in neonatal HIV-1 infection. More proficient diagnostic techniques made early diagnosis of HIV-1-infected neonates and infants possible during asymptomatic or mildly symptomatic disease stages. Major advances in treatment led to the control of viral replication and thereby altered the course of disease progression. HIV-1/AIDS-associated neurologic disorders declined in parallel. In countries where these therapies are readily available, a dramatic decline in the number of infants born HIV-1 infected has been realized as has a markedly improved survival rate of those infected. Many questions remain, however. The long-term effects of prenatal exposure to antiretroviral agents are not yet known and continue to be studied. Just exactly how HAART therapy may affect early signs of pediatric HIV-1/AIDS-associated CNS disease, should they develop, is unclear. As new anti-retroviral agents are developed and new combination drug regimens are instituted, the potential for neurologic complications, toxicities, and adverse drug interactions (e.g., with antiepileptic drugs (AEDS)) exists and needs to be identified and monitored.

The role of macrophage/microglia and astrocytes in the pathogenesis of three neurologic disorders: HIV-associated dementia, Alzheimer disease, and multiple sclerosis

Macrophage/microglia (M phi) are the principal immune cells in the central nervous system (CNS) concomitant with inflammatory brain disease and play a significant role in the host defense against invading microorganisms. Astrocytes, as a significant component of the blood-brain barrier, behave as one of the immune effector cells in the CNS as well. However, both cell types may play a dual role, amplifying the effects of inflammation and mediating cellular damage as well as protecting the CNS. Interactions of the immune system, M phi, and astrocytes result in altered production of neurotoxins and neurotrophins by these cells. These effects alter the neuronal structure and function during pathogenesis of HIV-1-associated dementia (HAD), Alzheimer disease (AD), and multiple sclerosis (MS). HAD primarily involves subcortical gray matter, and both HAD and MS affect sub-cortical white matter. AD is a cortical disease. The process of M phi and astrocytes activation leading to neurotoxicity share similarities among the three diseases. Human Immunodeficiency Virus (HIV)-1-infected M phi are involved in the pathogenesis of HAD and produce toxic molecules including cytokines, chemokines, and nitric oxide (NO). In AD, M phis produce these molecules and are activated by beta-amyloid proteins and related oligopeptides. Demyelination in MS involves M phi that become lipid laden, spurred by several possible antigens. In these three diseases, cytokine/chemokine communications between M phi and astrocytes occur and are involved in the balance of protective and destructive actions by these cells. This review describes the role of M phi and astrocytes in the pathogenesis of these three progressive neurological diseases, examining both beneficent and deleterious effects in each disease.

Central nervous system damage, monocytes and macrophages, and neurological disorders in AIDS

This review focuses on the role of the extended macrophage/monocyte family in the central nervous system during HIV or SIV infection. The accumulated data, buttressed by recent experimental results, suggest that these cells play a central, pathogenic role in retroviral-associated CNS disease. While the immune system is able to combat the underlying retroviral infection, the accumulation and widespread activation of macrophages, microglia, and perivascular cells in the CNS are held in check. However, with the collapse of the immune system and the disappearance of the CD4(+) T cell population, productive infection reemerges, especially in CNS macrophages. These cells, as well as noninfected macrophages, are stimulated to high levels of activation. When members of this cell group become highly activated, they elaborate a wide spectrum of deleterious substances into the neural parenchyma. In the final phases of HIV or SIV infection, this chronic, widespread, and dramatic level of macrophage/monocyte/microglial activation constitutes a self-sustaining state of macrophage dysregulation, which results in pathological alterations and the emergence of various neurological problems.

Neuropathogenesis of central nervous system HIV-1 infection

Neuronal damage and death are consistent pathologic findings in the brains of patients with ADC, and multiple cell model systems have demonstrated neurotoxicity through the effects of HIV-1 infection in macrophages and microglia. Brain MRI studies (1H-MRS) indicate that reversible neuronal cell dysfunction occurs early during the course of HIV-1 infection, long before overt symptoms of ADC appear. Epidemiologic studies suggest that a high viral load in the CNS is a major risk factor for ADC and that HAART may significantly reduce, but not eliminate, the risk of developing ADC. Targeted adjunctive therapies administered early are likely necessary to maximize CNS protection against HIV, and rational approaches to such therapy are rapidly evolving through in vitro analysis of the mechanisms of HIV-associated neurotoxicity. Soluble factors released by infected cells may directly or indirectly damage neurons and induce apoptosis at the level of NMDA subtype of glutamate receptors, and NMDA receptor antagonists represent a major therapeutic option currently under intense clinical investigation. Likewise, drugs with antioxidant or free radical scavenging effects offer another rational approach to adjunctive therapy and are also under intense clinical scrutiny. Finally, agents that inhibit neuronal death-signaling pathways (e.g., p38 MAPK inhibitors) and that stimulate cell survival pathways (e.g., Akt/PKB) may represent the next investigational step in designing anti-ADC therapies.

HIV: clinical manifestations

HIV infection in the United States appeared early in the 1980s, when previously healthy homosexual men manifested opportunistic infections attributable to apparent underlying immunodeficiency. After these initial isolated reports, there appeared many other groups of patients at risk for development of this devastating disease. From these meager beginnings, the problem has escalated exponentially. HIV infection can affect every system in the human body. Since the era of highly active antiretroviral therapy, however, the prevalence of opportunistic infections and HIV-AIDS clinical manifestations has declined dramatically. In addition to antiretroviral therapy, management of HIV-infected persons requires knowledge of the extent of system involvement, as well as highly active antiretroviral therapy-related adverse effects, so as to recognize complications and initiate appropriate intervention. In the following review we will attempt to comprehensively summarize the clinical manifestations of HIV infection for both pediatric and adult populations.

Neuroimmune and neurovirological aspects of human immunodeficiency virus infection

Like most lentiviruses, HIV-1 causes both immune suppression and neurological disease. Neurological disease may occur at any stage of HIV infection but is most apparent with severe immune suppression. Cognitive impairment, reflected strikingly by HIV-associated dementia, has attracted intense interest since the outset of the HIV epidemic, and understanding of its pathogenesis has been spurred on by the emergence of several hypotheses outlining potential pathogenic mechanisms. The release of inflammatory molecules by HIV-infected microglia and macrophages and the concurrent neuronal damage play central roles in the conceptualization of HIV neuropathogenesis. Many inflammatory molecules appear to contribute to the pathogenic cascade and their individual roles remain undefined. At the same time, the abundance of virus in the brain and the type or strain of virus found in the brain may also be important codeterminants of neurological disease, as shown for other neurotropic viruses. Coreceptor use by HIV found in the brain appears to closely mirror what has been reported in systemic macrophages. The impact of HAART on viral genotype and phenotype found in the brain, and its relationship to clinical disease, remain uncertain. Several interesting animal models have been developed, using other lentiviruses, transgenic animals, and HIV-infected SCID mice, that may prove useful in future pathogenesis and therapeutic studies. Despite the progress in the understanding of HIV neuropathogenesis, many questions remain unanswered.

A co-culture-based model of human blood-brain barrier: application to active transport of indinavir and in vivo-in vitro correlation

The growing array of in vitro models of the blood-brain barrier (BBB) which have been used makes it difficult to draw firm conclusions concerning the BBB penetration of HIV-1 protease inhibitors. What is needed is a combined in vivo and in vitro study on biological models that mimic as closely as possible the normal human BBB, to establish whether and how indinavir crosses the BBB. We developed a new human BBB model using primary endothelial cells and astrocytes. The biological relevance of this model was checked with respect on the one hand, to the close relationship between the log of drug permeability coefficient normalized to molecular weight and the log of the 1-octanol/water partition coefficient, and on the other hand to the functional P-glycoprotein (P-gp) expression. We employed this model to perform transport studies with indinavir and showed that the rate of in vitro indinavir transport from the basal to apical compartment was higher than the rate of apical to basal transport. Pretreatment of the BBB model with the P-gp inhibitor, quinidine, significantly increased apical to basal transport. Intracellular indinavir accumulation was increased in BBB as a result of inhibition of active transport. These data were correlated with the indinavir-mediated P-gp ATPase modulation showing that indinavir specifically interacted with a binding site on P-gp. Moreover, the activation of P-gp ATPase by indinavir was inhibited by quinidine. In addition, the in vivo brain to plasma concentration ratio of indinavir into mice showed that indinavir concentration was up to five times higher in the brain of mdr1a(-/-) mice than in the brain of mdr1a(+/+) mice. All these results confirm the role of P-gp in preventing the passage of indinavir across BBB and thus its entry into the central nervous system (CNS). Our human BBB model represents a useful tool for the evaluation of drug penetration into the CNS.

Assessment of HIV-intrathecal humoral immune response in AIDS-related neurological disorders

Intrathecal synthesis of IgG directed to HIV antigens was investigated by antibody specific index (ASI), affinity-mediated immunoblot (AMI) and Western blot (WB) assay in a group of 88 AIDS patients of which 28 with HIV-associated neurological disorders (HAND), 13 without associated neurological disorders (WAND) and 47 with non-HIV-associated neurological disorders (non-HAND). CD4+ count was above 50 cells/mm3 (CD4+>50) in 30 and below 50/mm3 (CD4+<50) in 58 patients, respectively. A significantly higher frequency for CSF complete anti-gag profile (p<0.001), and for HIV-specific oligoclonal patterns ("mixed" pattern=p<0.01) was observed in HAND as compared to patterns from the other clinical groups. A decrease in complete anti-env, anti-pol and anti-gag reactivity was present in CSF of patients with CD4+<50 as compared to those with CD4+>50. Our findings suggest that AIDS appears to be characterized by an anti-HIV intrathecal humoral immune response which is principally directed to env products with a prevalence of oligoclonal patterns and CSF complete anti-gag profile in HIV-associated neurological involvement.

Microglia in HIV-associated neurological diseases

Human immunodeficiency virus type-1 (HIV-1) is a neurotropic virus linked to a variety of progressive neurologic disorders. This review describes our current understanding of how HIV-1 enters the nervous system and interacts with neuronal and non-neuronal cells to initiate and sustain neurologic dysfunction. The overwhelming majority of cells infected with HIV-1 in the nervous system are microglia/macrophages. Microglial/macrophage infection leads to immune dysregulation as well as production and release of cytotoxic molecules. Interaction of these infected cells with astrocytes may accelerate neurotoxic mechanisms. A hypothetical scenario for how HIV-1 infection leads to neurologic disease is presented.

HIV-associated neuropathies: role of HIV-1, CMV, and other viruses

The role of the human immunodeficiency virus (HIV) and other viruses in the development of neuropathies associated with HIV infection is controversial. Distal symmetric polyneuropathy (DSP), the most common subtype of HIV-associated neuropathy, is characterized by an abundance of reactive macrophages within the peripheral nerve, but HIV replication is limited to a small percentage of the macrophages. Thus, the pathological destruction may be mediated by pro-inflammatory signals amplified by activated glial elements within the nerve, similar to the proposed mechanism of damage caused by HIV within the central nervous system. In contrast, in mononeuropathy multiplex (MM) and progressive polyneuropathy (PP), cytomegalovirus (CMV) replication in the peripheral nerve is consistently demonstrable, and this replication likely results in direct damage to the infected cells (neurons and glia). The rarest form of HIV-associated neuropathy, the diffuse infiltrative lymphocytosis syndrome (DILS), is characterized by an intense CD8+ T lymphocyte infiltration into the nerve and abundant HIV infection of macrophages. Finally, while other viruses (varicella zoster, herpes simplex) are associated with myelitis in HIV-infected individuals, there is little support for a role for these viruses in HIV-associated neuropathy.

HIV-1-associated central nervous system dysfunction

Despite more than 15 years of extensive investigative efforts, a complete understanding of the neurological consequences of HIV-1 CNS infection remains elusive. Although the resources of numerous investigators have been focused on studies of HIV-1-associated CNS disease, the complex nature of the disease processes that underlie the clinical, pathological, and cellular manifestations of HIV-1 CNS infection have required a larger volume of studies than was initially envisioned. Several major areas remain as the focus of current research efforts. One of the more pressing issues facing researchers and clinicians alike is the search for correlates to the development of HIV-1-associated CNS neuropathology and the onset of HIVD. Although numerous parameters have been studied, none have been shown to be absolute predictors or markers of HIV-1-related CNS dysfunction. The identification of solid correlates of HIVD is an important goal that would permit clinical identification of individuals at risk for developing potentially crippling, life-threatening CNS abnormalities and would facilitate early treatment of nascent neurological problems. A more complete comprehension of the cellular foundations of CNS dysfunction and HIVD is also a fundamental part of strategies designed to treat or prevent HIV-1-associated CNS disease. Future investigations will strive to expand the body of knowledge concerning the complex interactions between infected and uninfected neuroglial cells and the roles of numerous cytokines, chemokines, and other soluble agents that are deregulated during HIV-1 CNS infection. In particular, a thorough understanding of the mechanisms of neurotoxicity may facilitate the development of new therapies that alleviate or eliminate the clinical consequences of CNS infection. Finally, investigators will continue to study HIVD within the context of single and combination drug therapies used in the treatment of HIV-1 infection and AIDS. As newer and more effective systemic treatments for HIV-1 infection and AIDS are introduced, the effects of these treatments on the onset, incidence, and severity of HIVD will also require intensive study. The impact of drug therapies on the ability of the CNS to act as an HIV-1 reservoir will also need to be addressed. Introduction of each new drug or drug combination will necessitate studies of drug penetration into the CNS and efficacy against the development of CNS abnormalities. Furthermore, as more effective treatments prolong the lifespan of individuals infected with HIV-1, the impact of extended survival on the occurrence and severity of HIVD will also require further investigations. The quest for answers to these and other questions will be complicated by the diversity of experimental systems used to study different aspects of HIV-1 CNS infection and HIVD. Each system has its own unique strengths and weaknesses. Clinical observations provide a continuous spectrum of symptomatic findings but reveal little about the underlying mechanisms of disease. In vivo imaging techniques, such as CT and MRI, also provide a continuum of observations, but the images are limited in their resolution. Neuropathological examinations of postmortem HIV-1-infected brains offer gross, cellular, and molecular views (including phenotypic and genotypic analyses of CNS viral isolates) of the diseased brain, but only provide a snapshot of the end-stage neurologic dysfunction. Studies that rely on animal surrogates for HIV-1, including SIV, simian-HIV (SHIV), feline immunodeficiency virus (FIV), visna virus, and HIV-1 SCID-hu models, permit experimental protocols that cannot be carried out in humans, but are limited by the fidelity with which each virus and animal model emulates the conditions and events observed in the human host. Finally, in vitro techniques, which include the use of primary cells and cell lines, adult or fetal human cell cultures, and BBB barrier model systems, are also convenient means by which aspe

Mechanisms for adaptation of simian immunodeficiency virus to replication in alveolar macrophages

In contrast to the simian immunodeficiency virus SIVmac239, which replicates poorly in rhesus monkey alveolar macrophages, a variant with nine amino acid changes in envelope (SIVmac239/316E) replicates efficiently and to high titer in these same cells. We examined levels of viral DNA, RNA, antigen, and infectious virus to identify the nature of the block to SIVmac239 replication in these cells. Low levels of viral antigen (0.1 to 1.0 ng of p27 per ml) and infectious virus (100 to 1,000 infectious units per ml) were produced in the supernatant 1 to 4 days after SIVmac239 infection, but these levels did not increase subsequently. SIVmac239 DNA was synthesized in these macrophage cultures during the initial 24 h after infection, but the levels did not increase subsequently. Quantitation of the numbers of infectious cells in cultures over time and the results of experiments in which cells were reexposed to SIVmac239 after the initial exposure indicated that only a small proportion of cells were susceptible to SIVmac239 infection in these alveolar macrophage cultures and that the vast majority (>95%) of cells were refractory to SIVmac239 infection. In contrast to the results with SIVmac239, the levels of viral antigen, infectious virus, and viral DNA increased exponentially 2 to 7 days after infection by SIVmac239/316E, reaching levels greater than 100 ng of p27 per ml and 100,000 infectious units per ml. Since SIVmac239/316E has previously been described as a virus capable of infecting cells in a relatively CD4-independent fashion, we examined the levels of CD4 expression on the surface of fresh and cultured alveolar macrophages from rhesus monkeys. The levels of CD4 expression were extremely low, below the limit of detection by flow cytometry, on greater than 99% of the macrophages. CCR5(+) cells were profoundly depleted only from alveolar macrophage cultures infected with SIVmac239/316E. High concentrations of an antibody to CD4 delayed but did not block replication of SIVmac239/316E. The results suggest that the adaptation of SIVmac316 to efficient replication in alveolar macrophages results from its ability to infect these cells in a CD4-independent fashion or in a CD4-dependent fashion even at extremely low levels of surface CD4 expression. Since resident macrophages in brains and lungs of humans also express little or no CD4, our findings predict the presence of human immunodeficiency virus type 1 that is relatively CD4 independent in the lung and brain compartments of infected people.

Higher HIV-1 RNA cutoff level required in cerebrospinal fluid than in blood to predict positive HIV-1 isolation

HIV-1 can be isolated from the vast majority of blood samples taken from HIV-1-seropositive patients not treated with antiretroviral drugs. Isolation rates from cerebrospinal fluid (CSF) samples are considerably lower, ranging between 20-70%. The objective of this study was to determine the cutoff levels for HIV-1 RNA that would yield a positive predictive value > or =90% for positive virus isolation from CSF and blood. Quantitative HIV-1 RNA PCR (Amplicor HIV monitor, version 1.0, Roche Diagnostic Systems) and virus isolation were used to examine 303 CSF samples and 278 paired blood samples from 157 HIV-1-seropositive patients. Patients on antiretroviral treatment provided 140 of the CSF samples and 131 of the blood samples. CSF samples that were positive by culture numbered 137 of 303 (45%), as compared with 216 of 278 (78%) blood samples. In the case of samples taken from patients with antiretroviral treatment, 28% were positive by culture from CSF and 63% from blood. As expected, mean HIV-1 RNA levels were higher in CSF and blood samples positive by culture than in samples negative by culture. A cutoff level of >5,000 HIV-1 RNA copies/ml was required to yield a positive predictive value for positive virus isolation from CSF samples of > or =90%, whereas the cutoff level for blood samples was just above the detection limit of the assay (>200 HIV-1 copies/ml).

Human immunodeficiency virus glycoprotein 160 induces cytokine mRNA expression in the rat central nervous system

1. Elevated proinflammatory cytokines within the central nervous system (CNS) of individuals infected with human immunodeficiency virus (HIV) may contribute to altered CNS processes prior to the onset of AIDS. Most studies of HIV-induced alterations in cytokine expression within the CNS have focused on interleukin (IL)-1 and tumor necrosis factor (TNF). 2. We used a ribonuclease protection assay (RPA) to elucidate further the pattern of cytokine mRNA expression in the rat CNS in response to HIV envelope glycoprotein 160 (gp160). Male Sprague-Dawley rats were surgically implanted with a guide cannula directed into a lateral cerebral ventricle. HIV gp160 was injected intracerebroventricularly and rats were sacrificed immediately (time = 0) or at 1, 2, or 4 hr postinjection. Discrete brain regions were dissected, and peripheral glands removed. All tissues were frozen in liquid nitrogen until RNA extraction and assay. 3. IL-1beta IL-1alpha, TNF-alpha, and TNFbeta mRNAs were constitutively expressed in brain tissues. Central administration of gp160 dramatically increased mRNA expression for IL-1beta and TNFalpha in the hypothalamus, hippocampus, brainstem, and cerebellum. Furthermore, although mRNA expression for IL-5, IL-6, and IL-10 was never detected under basal conditions, these mRNAs were increased in brain tissue after administration of gp160. Peak expression in each brain region was detected 2 hr after administration. Multiple cytokine mRNAs were detected in peripheral tissues, but their expression was not altered by central administration of gp160. 4. Our results indicate that gp160 induces mRNA expression in brain for cytokines other than IL-1 and TNF. Screening for multiple cytokine mRNA in this manner provides extensive information concerning the particular cytokines that may be involved in HIV-induced pathologies and alterations in CNS processes.

Early detection of neurophysiological abnormalities in infection by human immunodeficiency virus

The human immunodeficiency virus causes serious, progressive and irreversible deterioration of the immunocompetence system and of the nervous system, so neurological pathology in infected patients is frequent (30-40%), affecting both the central and the peripheral nervous systems. There are different clinical and laboratory indicators of bad prognosis, considering the important neurotropism of the virus. This study attempts to evaluate which neurophysiological parameters are altered during the initial phases of infection by HIV. A total of 46 individuals were studied, 30 seronegative and 16 seropositive in stage A of the CDC-93 classification. Motor and sensory conduction studies were carried out on all of them on the upper and lower extremities, as well as visual, somatosensory and auditory evoked potentials and endogenous potentials, mainly P300. The analysis of the neurophysiological parameters evaluated in our series, showed alterations of the conduction velocity of the sural nerve, latency of N1 of the SSEP of median and posterior tibial nerves and P300 in the initial phases of the infection even in the absence of clinical symptomatology.

Management of HIV-infected children in the home and institutional settings. Care of children and infections control in schools, day care, hospital settings, home, foster care, and adoption

The likelihood of high-risk pediatric exposure to HIV infection, other than perinatal exposure, has been shown to be low in most cases, and HIV PEP should be considered on a case-by-case basis. Generic considerations in the management of children who have become HIV infected emphasizes the principles of inclusion, maintaining confidentiality of a child's HIV status, and notifying those who need to know about the HIV status to care properly for the child or adolescent. Although appropriate infection-control precautions are applicable for all children and for many pathogens, children especially HIV-infected children, exposed to such pathogens, must be managed in a timely fashion. In many cases, recommendations that are applicable in one setting are applicable in others. Some exceptions apply, including infection-control precautions in hospitals versus other settings. A few additional considerations have been made for special settings and activities, including adoption, foster care, athletics, summer camp, and other recreational activities.

Glioblastoma multiforme in a case of acquired immunodeficiency syndrome: investigation a possible oncogenic influence of human immunodeficiency virus on glial cells. Case report and review of the literature

Malignant glioma is the most common primary brain neoplasm, but generally it is not included in the differential diagnosis of enhancing lesions of the central nervous system (CNS) in patients suffering from acquired immunodeficiency syndrome. We report a case of glioblastoma multiforme (GBM) in a 29-year-old man with human immunodeficiency virus (HIV). Primary CNS lymphoma was suspected, making a definitive histological diagnosis crucial. An initial stereotactic biopsy sample was insufficient to establish a diagnosis and a second biopsy of the lesion was obtained. The histopathological investigation confirmed GBM and adjuvant external radiation treatment was given to the patient, who survived for 4 months after the initial biopsy. A decline in the rate of Toxoplasma infection and the changing diseases observed in HIV infection indicate the importance of obtaining a biopsy in cases of CNS mass lesions.

Pharmacokinetics of (-)-beta-D-dioxolane guanine and prodrug (-)-beta-D-2,6-diaminopurine dioxolane in rats and monkeys

(-)-beta-D-Dioxolane guanine (DXG) is a nucleoside analog possessing potent activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), and hepatitis B virus (HBV) in vitro. Owing to the limited aqueous solubility of DXG, (-)-beta-D-2,6-diaminopurine dioxolane (DAPD), a more water-soluble prodrug of DXG, is being developed for clinical use. The purpose of this study was to characterize the pharmacokinetics of DXG after administration of DXG and DAPD to rats and monkeys. After intravenous administration of DXG, plasma concentrations of the nucleoside declined in a biexponential manner, with a terminal-phase half-life of 0.44 +/- 0.14 hr (mean +/- SD) in rats and 2.3 hr in monkeys. Total clearance of DXG was 4.28 +/- 0.99 liters/hr/kg in rats and 0.72 liters/hr/kg in monkeys. Renal excretion of unchanged DXG accounted for approximately 50% of total clearance in both species. Steady state volume of distribution of DXG was 2.30 liters/kg in rats and 1.19 liters/kg in monkeys. After intravenous administration of DAPD to rats, prodrug concentrations declined with a half-life of 0.37 +/- 0.11 hr. DXG was rapidly generated from DAPD, with approximately 61% of the dose of DAPD being converted to DXG. After administration of DAPD to monkeys, only concentrations of metabolite DXG could be determined owing to rapid conversion of DAPD to DXG during sample collection. The half-lives of DAPD and DXG after intravenous administration determined from urinary excretion data were 0.8 +/- 0.4 and 1.6 +/- 0.2 hr, respectively. Oral bioavailability of DAPD was estimated to be approximately 30%.

Stable expression of HIV-1 Nef induces changes in growth properties and activation state of human astrocytes

OBJECTIVE

Nef was shown to be the predominant viral protein expressed in HIV-1-infected astrocytes in vivo and in vitro suggesting a distinct role of Nef in this cell type. Nef-induced activation of T cells is well described, whereas the functional activities of Nef in astrocytes are unknown. Our aim was to examine the effect of Nef on growth properties and activation of astrocytes.

DESIGN

Human Nef-expressing astrocytic cell lines were established by stable transfection with different wild-type and mutant nef genes derived from laboratory isolates and brain tissue.

METHODS

Nef-expressing astrocytes were characterized in terms of growth properties (proliferation, growth in soft agar, focus formation) and morphology. Apoptotic cell death and expression of activation markers were determined by fluorescent antibody cell sorting.

RESULTS

Astrocytic cell lines revealed persistent Nef expression--detectable at the levels of mRNA and protein--and showed altered growth properties and morphology. Elevated expression of activation markers such as glial fibrillary acidic protein and CD88 (complement receptor C5a) was observed; these are regarded as markers for inflammatory processes in the brain. This effect was independent of the nef type or the expression level of the Nef protein. In contrast with previous reports no evidence for increased apoptotic cell death was found in astrocytes expressing Nef stably.

CONCLUSIONS

Our findings suggest that Nef changes the cellular properties of astrocytes, thus contributing to astrocyte activation and induction of astrogliosis in the central nervous system of individuals with AIDS.

Relation of peripheral neuropathy to HIV treatment in four randomized clinical trials including didanosine

Peripheral neuropathy has been recognized as a dose-limiting adverse effect in Phase I studies of didanosine (ddI) therapy for HIV infection. To study the effect of the currently recommended lower dose of ddI, the databases of 4 randomized, controlled trials were used to assess the frequency of dose-limiting peripheral neuropathy during treatment with ddI 500 or 750 mg/d, compared with zidovudine (ZDV) monotherapy or combination therapy with ddI/ZDV or zalcitabine/ZDV. No between-group differences in risk factors for neuropathy (eg, infectious and metabolic factors, malignancy, concurrent medications) were observed in the individual trials, and the presence of these risk factors appeared to have no increased treatment effect on the occurrence of neuropathy. No significant between-group differences were observed in the individual studies with regard to the incidence or time to onset of peripheral neuropathy. Analysis of the combined results by treatment regimen showed no significant difference in the incidence of neuropathy between recipients of ddI 500 mg/d, ddI 750 mg/d, or ZDV and no significant difference in the cumulative dose received until the onset of neuropathy between the ddI 500- and 750-mg regimens. Entry CD4+ cell counts were significantly predictive of neuropathy, with each 100-cell/microL decrement associated with a 17% increase in risk (P = 0.002); a CD4+ cell count of <50 cells/microL was highly predictive of neuropathy (P = 0.0001). In summary, the risk for peripheral neuropathy was not increased by treatment with ddI versus comparator regimens or by treatment with ddI at the dosages used in studies conducted more recently than the Phase I trials. Peripheral neuropathy seems more likely to be associated with advanced HIV infection and lower CD4+ cell counts (particularly counts <50 cells/microL) than with ddI therapy at the currently recommended dose.

Inflammatory Cytokines and HIV-1-Associated Neurodegeneration: Oncostatin-M Produced by Mononuclear Cells from HIV-1-Infected Individuals Induces Apoptosis of Primary Neurons

Neurologic abnormalities are common in HIV-1-infected patients and often represent the dominant clinical manifestation of pediatric AIDS. The neurological dysfunction has been directly related to CNS invasion by HIV-1 that is principally, if not exclusively, supported by blood-derived monocytes/macrophages and lymphocytes. By using primary long term cultures of human fetal sensory neurons as well as sympathetic precursors-like neuronal cells, we determined that blood-derived mononuclear cells from HIV-1-infected individuals spontaneously release soluble mediators that can potently inhibit the growth and survival of developing neurons as well as the viability of postmitotic neuronal cells by inducing apoptotic cell death. Analysis of the cytokines produced by lymphomonocytic cells, HIV-1 infected or activated, indicated that oncostatin M (oncM) is a major mediator of these effects. Since low TGF-β1 concentrations were capable of enhancing oncM-mediated neuronal alterations, our data indicate that by acting in concert with other cytokines, oncM may induce neuronal demise in both the developing and the mature brain. Thus, this cytokine may contribute to the setting of the neuronal cell damage observed in HIV-1-infected individuals.

Primary intracranial neoplasms in patients with HIV

OBJECTIVE

To report a series of HIV-infected patients with intracranial tumors not known to be associated with immunodeficiency.

BACKGROUND

The spectrum of HIV-associated diseases is changing with improved treatments and prolonged patient survival. Although primary central nervous system lymphoma (PCNSL) and toxoplasmosis continue to be the most common intracranial lesions in HIV-infected patients, the recognition of other pathologic entities is increasingly important.

METHODS

The clinical characteristics and outcome of eight HIV-infected patients with nine intracranial neoplasms other than PCNSL are reported. In addition, all available pathologic specimens were tested for evidence of either HIV or Epstein-Barr virus (EBV) infection. An additional 28 patients reported in the literature are summarized.

RESULTS

Five of eight patients had a glioblastoma multiforme; other tumors included an anaplastic ependymoma, a low-grade glioma, a subependymoma, and a leiomyosarcoma. More than half of the patients developed their tumor > or =6 years after the diagnosis of HIV infection. Patient prognosis and survival was best predicted by tumor histology. Treatment response and outcome did not appear to be influenced by HIV infection. Only the leiomyosarcoma demonstrated evidence of latent EBV infection.

CONCLUSIONS

HIV-infected patients are at risk for intracranial neoplasms other than PCNSL, and benefit from aggressive tumor-specific therapy. It is possible that gliomas are occurring at a higher rate than in the general population. There was no evidence of HIV or EBV infection in any glial tumor.

HIV infection of fetal human astrocytes: the potential role of a receptor-mediated endocytic pathway

HIV infects microglia and astrocytes both in vivo and in vitro. Although there is a significant amount of information about microglial infection, data regarding astrocytes are more limited. For example, little is known about the initial membrane events occurring between HIV and astrocytes. Also, the mechanism by which HIV enters these cells remains to be determined. To address these questions, we exposed human astrocyte cultures to either HIV or to the HIV glycoprotein gp120. The cultures were analyzed for viral infection and gp120 binding to cultured cells by light and electron microscopy (EM) with and without immunocytochemistry, respectively; ligand-receptor biochemistry; and, Western, Northern and Southern blot analyses. The results of these studies showed that HIV binds to astrocytes via gp120 and a cell surface molecule weighing approximately 65 kDa that is neither CD4 nor galactocerebroside. Furthermore, binding of gp120 to astrocytes was concentration dependent and displayed a curve consistent with ligand-receptor binding. Additionally, radiolabeled gp120 binding was displaced by unlabeled gp120 but not by deglycosylated gp120, suggesting that the binding was specific. By EM, HIV virions were seen in clathrin-coated pits and in cytoplasmic vacuoles. This suggests linkage, in astrocytes, between a plasma membrane-associated protein that can act as a receptor for HIV and an endosomal pathway.

Coalescent estimates of HIV-1 generation time in vivo

The generation time of HIV Type 1 (HIV-1) in vivo has previously been estimated using a mathematical model of viral dynamics and was found to be on the order of one to two days per generation. Here, we describe a new method based on coalescence theory that allows the estimate of generation times to be derived by using nucleotide sequence data and a reconstructed genealogy of sequences obtained over time. The method is applied to sequences obtained from a long-term nonprogressing individual at five sampling occasions. The estimate of viral generation time using the coalescent method is 1.2 days per generation and is close to that obtained by mathematical modeling (1.8 days per generation), thus strengthening confidence in estimates of a short viral generation time. Apart from the estimation of relevant parameters relating to viral dynamics, coalescent modeling also allows us to simulate the evolutionary behavior of samples of sequences obtained over time.

Neurotological auditory brain stem response findings in human immunodeficiency virus-positive patients without neurologic manifestations

Neurologic manifestations of human immunodeficiency virus (HIV) infection, rather than being a late complication of the disease, are principally correlated with the early central nervous system (CNS) localization of HIV. The CNS may be infected in the early stages of acquired immunodeficiency syndrome (AIDS) without evidence of neurologic disorders. Evoked potentials (visual, auditory, and somatosensory) and electronystagmographic test batteries have proven to be very sensitive in showing subclinical CNS disorders due to HIV. In this study, auditory brain stem response (ABR) and electronystagmographic test battery findings (smooth pursuit, saccades, caloric test) were performed in 29 neurologically asymptomatic, HIV-positive subjects at different stages of the disease. Compared to results of a control group, the ABR latencies of waves V, I, and III and interpeaks I-V and III-V were significantly increased in HIV patients. The same parameters did not differ significantly among the stages of the disease. In HIV-positive subjects, the accuracy of saccades was significantly reduced, while latency was normal. The velocity and the gain of pursuit were significantly reduced in HIV-positive patients, and 15 of 29 patients showed corrective saccades. Caloric tests revealed qualitative nystagmus abnormalities in 82% of HIV patients, while quantitative parameters were normal. The present results confirm that CNS involvement by HIV occurs early in the course of the disease. In particular, HIV does not seem to affect the labyrinth or the eighth cranial nerve, as demonstrated by the normality of the I-III value of the ABR and of the quantitative parameters of the caloric responses, but it does appear to involve the brain stem acoustic pathways, pontocerebellar pathways, and supratentorial areas.

Interaction of anti-HIV protease inhibitors with the multidrug transporter P-glycoprotein (P-gp) in human cultured cells

The anti-HIV protease inhibitors represent a new class of agents for treatment of HIV infection. Saquinavir, ritonavir, indinavir, and nelfinavir are the first drugs approved in this class and significantly reduce HIV RNA copy number with minimal adverse effects. They are all substrates of cytochrome P450 3A4, and are incompletely bioavailable. The drug transporting protein, P-glycoprotein (P-gp), which is highly expressed in the intestinal mucosa, could be responsible for the low oral bioavailability of these and other drugs which are substrates for this transporter. To determine whether these protease inhibitors are modulators of P-gp, we studied them in cell lines which do and do not express P-gp. Saquinavir, ritonavir and nelfinavir significantly inhibited the efflux of [3H]paclitaxel and [3H]vinblastine in P-gp-positive cells, resulting in an increase in intracellular accumulation of these drugs. However, similar concentrations of indinavir did not affect the accumulation of these anticancer agents. In photoaffinity labeling studies, saquinavir and ritonavir displaced [3H]azidopine, a substrate for P-gp, in a dose-dependent manner. These data suggest that saquinavir, ritonavir, and nelfinavir are inhibitors and possibly substrates of P-gp. Because saquinavir has a low bioavailability, its interaction with P-gp may be involved in limiting its absorption.

Isolation and characterization of a neuropathogenic simian immunodeficiency virus derived from a sooty mangabey

Transfusion of blood from a simian immunodeficiency virus (SIV)- and simian T-cell lymphotropic virus-infected sooty mangabey (designated FGb) to rhesus and pig-tailed macaques resulted in the development of neurologic disease in addition to AIDS. To investigate the role of SIV in neurologic disease, virus was isolated from a lymph node of a pig-tailed macaque (designated PGm) and the cerebrospinal fluid of a rhesus macaque (designated ROn2) and passaged to additional macaques. SIV-related neuropathogenic effects were observed in 100% of the pig-tailed macaques inoculated with either virus. Lesions in these animals included extensive formation of SIV RNA-positive giant cells in the brain parenchyma and meninges. Based upon morphology, the majority of infected cells in both lymphoid and brain tissue appeared to be of macrophage lineage. The virus isolates replicated very well in pig-tailed and rhesus macaque peripheral blood mononuclear cells (PBMC) with rapid kinetics. Differential replicative abilities were observed in both PBMC and macrophage populations, with viruses growing to higher titers in pig-tailed macaque cells than in rhesus macaque cells. An infectious molecular clone of virus derived from the isolate from macaque PGm (PGm5.3) was generated and was shown to have in vitro replication characteristics similar to those of the uncloned virus stock. While molecular analyses of this virus revealed its similarity to SIV isolates from sooty mangabeys, significant amino acid differences in Env and Nef were observed. This virus should provide an excellent system for investigating the mechanism of lentivirus-induced neurologic disease.

The transport of the anti-HIV drug, 2',3'-didehydro-3'-deoxythymidine (D4T), across the blood-brain and blood-cerebrospinal fluid barriers

1. The brain is a site of infection, viral replication and sanctuary for HIV-1. The treatment of HIV-1 infection therefore requires that an effective agent be delivered to the brain. 2',3'-Didehydro-3'-deoxythymidine (D4T) is a nucleoside analogue which has been shown to have beneficial clinical effects in the treatment of HIV infection. However, although D4T has been detected in human CSF, the ability of this drug to cross both the blood-brain and blood-cerebrospinal fluid (CSF) barriers and gain entrance into the brain tissue is not known. 2. This study examined the CNS entry of D4T by means of the bilateral vascular brain perfusion technique in the anaesthetized guinea-pig. 3. The results indicated that [3H]-D4T had a limited ability to cross the blood-brain barrier (BBB), which was not significantly greater than D-[14C]-mannitol (a slowly penetrating marker molecule). Although D4T was found to cross the blood-CSF barrier, the presence of D4T in the CSF did not reflect levels of the drug in the brain tissue. 4. These results can be related to the measured low lipophilicity of D4T, the higher paracellular permeability characteristics of the choroid plexus (blood-CSF barrier) compared to the BBB, and the sink action nature of the CSF to the brain tissue. 5. In conclusion, these animal studies suggest that D4T may only penetrate the brain tissue to a limited extent and consideration should be given to these findings in the clinical situation.

Low blood-brain barrier permeability to azidothymidine (AZT), 3TC, and thymidine in the rat

The blood-brain barrier (BBB) permeability to [3H]-azidodeoxythymidine (AZT), deoxythiacytidine (3TC), and thymidine was studied using both an intravenous injection/external organ (IV/EO) method and an internal carotid artery perfusion (ICAP) technique in parallel with [14C]-sucrose as a plasma volume marker. The brain volumes of distribution (VD) of the three compounds approximated that of sucrose with either method. Although the lipid solubility of AZT, as determined by the 1-octanol/buffer partition coefficient (P), was 16-fold higher than that of thymidine, the BBB permeability-surface area (PS) products were almost identical, consistent with preferential efflux of AZT from brain to blood.

HIV-associated brain pathology: a comparative international study

Little is known about the frequency and variation of HIV-associated brain pathology in different geographical centres. To assess whether there is an association between the frequency of disease and demographic factors we examined the neuropathological findings in four European and two American cities. The cities included London, Edinburgh, Paris, Budapest, Baltimore and Newark. Information was collected on a total of 1144 cases. HIV encephalitis was the most common observation in all the centres. although its frequency varied between them (P < 0.01). Furthermore, there were significant differences (P < 0.001) between the various categories of exposure and the frequency of HIV encephalitis in Edinburgh and other centres. The occurrence of toxoplasmosis, progressive multifocal leukoencephalolpathy (PML) and cryptococcal infection also differed between the various centres (P < 0.01). None of the findings was attributable to age, sex, or ethnic origin, but the introduction of anti-retroviral treatment, such as Zidovudine, may have been important. Overall, this study highlights geographical variability and the potential importance for group of exposure and anti-retroviral medication as factors affecting the development of various HIV-associated brain lesions.

Neurologic manifestations of HIV infection. Using imaging studies and antiviral therapy effectively

Patients with HIV infection are at risk for neurologic complications that can arise through various means. Nervous system disorders sometimes occur as a direct consequence of the HIV infection itself. Or, as immunodeficiency progresses, patients can become susceptible to numerous opportunistic infections and other conditions that have neurologic involvement. Even the antiviral drugs used to treat HIV infection can induce neurologic manifestations. Dr Rachlis discusses several of these manifestations and their management.

HIV gp120 inhibits the somatotropic axis: a possible GH-releasing hormone receptor mechanism for the pathogenesis of AIDS wasting

AIDS is often associated with growth retardation in children and wasting in adults. The dissociated envelope protein of the HIV (HIV-1), gp120, can be found in significant concentrations in the parenchyma and cerebrospinal fluid of brains in infected individuals, even in the earliest stages of HIV-1 disease. On the basis of this and the fact that we observed pentapeptide sequence homology between GH-releasing hormone (GHRH) and the V2 receptor-binding region of gp120, we initiated experiments to determine whether gp120 could affect GH secretion and growth in vivo and/or interact with anterior pituitary GHRH receptors in vitro. Although acute IV administration of gp120 in conscious rats had no effect on plasma GH levels, acute administration of gp120 (400 ng) into the brain significantly suppressed pulsatile GH release over a 6-h period compared with saline-injected controls. Furthermore, the putative gp120 antagonist, Peptide T (DAPTA), prevented the suppression of GH by gp120. In support of these in vivo findings, gp120 also significantly (P < 0.05) suppressed GHRH-stimulated GH release in static cultures of dispersed pituitary cells and from cells undergoing perifusion with the peptides. DAPTA prevented the GH suppression by gp120 in both of the pituitary cell paradigms. Furthermore, chronic administration of gp120 into the third ventricle significantly reduced body weight in juvenile rats, compared with saline-injected controls. Thus, gp120 appears to act both at the hypothalamus and pituitary to suppress GH release, and its action at these two locations is associated with a significant loss in body weight in chronically treated young animals. These findings may suggest a specific mechanism for the pathogenesis of wasting in HIV-1 patients that involves blockade of endogenous GHRH receptors by gp120.

HLA-DR-positive dendritic cells of the normal human choroid plexus: a potential reservoir of HIV in the central nervous system

In a previous study of choroid plexus (CPx) from patients with the acquired immunodeficiency syndrome (AIDS), we found a population of stromal cells infected with the human immunodeficiency virus (HIV). To determine whether these represented antigen-presenting dendritic cells, we examined the phenotype of normal human choroid plexus by light and electron microscopy (EM) and established the HIV-infected cell type by immunohistochemistry in AIDS cases with HIV-infected CPx. Monoclonal antibodies were used to detect class II major histocompatibility antigens (MHC), S-100 and S-100beta protein, lymphocytes, monocytes/macrophages, and HIV glycoprotein. A variable number of stromal cells had slightly elongated nuclei and long branching processes that were strongly immunoreactive for class II MHCs, rarely reactive for S-100 and S-100beta and immunonegative for monocyte/macrophage markers. Phagocytic activity was absent by EM and immunomarkers. They were numerous in the subepithelial region, and their processes occasionally extended toward the stromal capillaries or between the CPx epithelial cells. The HIV-infected cells were intensely immunoreactive for class II MHC markers and often displayed a dendritic morphology. These results document the presence of dendritic cells in the normal human CPx whose morphology and immunophenotype closely resemble those of DCs elsewhere in the body. They also show that these immunoreactive MHC class II cells are the cell type infected by HIV. We suggest that the functional activity of the CPx DCs is similar to that of antigen-presenting dendritic cells elsewhere in the body. This includes the potential to harbor HIV during the prolonged period of clinical latency, acting as a central nervous system reservoir of infection before the onset of AIDS.