Advanced breast cancer incidence following population-based mammographic screening.

BACKGROUND: Breast cancer mortality is declining in many Western countries. If mammography screening contributed to decreases in mortality, then decreases in advanced breast cancer incidence should also be noticeable. PATIENTS AND METHODS: We assessed incidence trends of advanced breast cancer in areas where mammography screening is practiced for at least 7 years with 60% minimum participation and where population-based registration of advanced breast cancer existed. Through a systematic Medline search, we identified relevant published data for Australia, Italy, Norway, Switzerland, The Netherlands, U.K. and the U.S.A. Data from cancer registries in Northern Ireland, Scotland, the U.S.A. (Surveillance, Epidemiology and End Results (SEER), and Connecticut), and Tasmania (Australia) were available for the study. Criterion for advanced cancer was the tumour size, and if not available, spread to regional/distant sites. RESULTS: Age-adjusted annual percent changes (APCs) were stable or increasing in ten areas (APCs of -0.5% to 1.7%). In four areas (Firenze, the Netherlands, SEER and Connecticut) there were transient downward trends followed by increases back to pre-screening rates. CONCLUSIONS: In areas with widespread sustained mammographic screening, trends in advanced breast cancer incidence do not support a substantial role for screening in the decrease in mortality.

Quantification of changes in breast cancer incidence and mortality since 1990 in 35 countries with Caucasian-majority populations.

BACKGROUND: Since 1985 considerable changes have taken place in the early detection and treatment of breast cancer. We quantified breast cancer trends for 35 countries with populations mainly of European ancestry. METHODS: Incidence data were extracted from cancer registries and mortality data from World Health Organization database. Overall percentage change from 1990 to 2002 was quantified for all ages and for three different age-groups (35-49, 50-69 and >/=70 years of age). RESULTS: The incidence percent change in women of all ages varied from 2.1% in Canada to 54.2% in Lithuania. Main increases in incidence were observed for women 50-69 years old, from 12.4% in Canada until 105.3% in Norway. Decreases in mortality of >20% were observed in nine countries. Mortality decreases were highest in women 35-49 years old and lowest in women >/=70 years. The magnitude of mortality decrease from 1990 to 2002 was not related to the mortality rate observed in 1990. CONCLUSIONS: While increases in breast cancer incidence mainly concerned women >/=50 years, decreases in mortality were more marked in women 35-49 years old. Large disparities in changes in mortality rates probably reflect differences in detection of and management of breast cancer.

Changes in breast cancer incidence and mortality in middle-aged and elderly women in 28 countries with Caucasian majority populations.

BACKGROUND: Mammography screening and menopause hormone therapy is essentially offered to women 50-69 years old. METHODS: In 28 European ancestry countries, we quantified changes in breast cancer incidence and mortality using a joinpoint regression analysis from 1960 until last year of available data. RESULTS: Since 1960, increases in incidence often in the order of 2%-3% per year occurred in all countries, mainly in women 50-69 years old whose incidence in eight countries surpassed the incidence in women 70 years old and more. In 10 countries, a decrease in incidence in women >or=70 years was noticeable in the last years of observation, but the magnitude of this decrease was far from matching the magnitude of the increases observed in the 50-69 age-group. In the beginning of years 2000s, a persistent decrease in mortality of approximately 2% per year was observed in women 50-69 years old in most countries and parallel declines in mortality were observed in women 70 years or more. CONCLUSIONS: In years 2000s, in a number of countries, the incidence of breast cancer has become greater in middle-aged women than in older women. If trends remain unchanged, the same phenomenon is likely to happen in other countries.

Women's perceptions of events impeding or facilitating the detection, investigation and treatment of breast cancer.

An integrated network is currently being implemented in the province of Quebec in order to improve the cancer care continuum. In this context, formal trajectories for cancer patients through healthcare services are being established. The investigation of patients' perceptions of the healthcare continuum is essential as it allows us to identify the issue of continuity/discontinuity of health services. In addition, patients' perceptions of continuity of cancer care should be documented since they could influence the implementation of optimal trajectories through the healthcare services. An exploratory qualitative study was conducted in order to identify events, based on the perceptions of women with breast cancer, that made the patient progress more rapidly, facilitating events, or more slowly, impeding events, within the cancer care continuum. Two consecutive series of women receiving adjuvant radiation therapy in 2002 and 2003 at the University Hospital of Quebec City were recruited, for a total of 120 participants. A semi-structured interview was administered in order to identify women's perceptions regarding impeding and facilitating events during the detection, investigation and treatment periods of cancer, as well as the actors and reasons involved. Overall, 64% of women reported having at least one impeding event, while 68% reported at least one facilitating event. The periods most frequently affected by impeding or facilitating events were the investigation period, followed by the treatment period. The main stages affected by impeding or facilitating events were the scheduling of an appointment, during the investigation period, and the onset of treatment. Impeding events particularly affected the scheduling of mammography, the initial exam of the investigation for breast cancer, as well as the onset of radiation treatment. On the other hand, facilitating events mainly occurred at the time of the scheduling of medical consultations with specialists, during the investigation period, and of the onset of surgery. Finally, women generally perceived that impeding events were due to a lack in the availability of services and that facilitating events resulted from human intervention. Patients' perceptions, such as those regarding the importance of human intervention in the process of continuity of care, should be taken into account by healthcare authorities in charge of implementing cancer control programmes.

The expression of thyrotropin receptor in the brain.

The regulation of the thyroid gland by TSH is mediated by a heterotrimeric G protein-coupled receptor. Nonthyroid effects of TSH have been reported, and expression of its receptor has been described in adipocytes and lymphocytes. We have previously reported the existence of specific and saturable binding sites of TSH and specific TSH effects in primary cultured rat brain astroglial cells. We now report expression of the TSH receptor gene in these cells; the coding sequence of the corresponding complementary DNA is identical to that previously established in thyroid. Using specific antisense RNA probe, expression of this gene was detected in some isolated or clustered glial fibrillary acidic protein-positive primary cultured cells by in situ hybridization. With this technique, we further detected TSH receptor messenger RNA (mRNA) expression in rat brain cryoslices in both neuronal cells and astrocytes. Its presence predominated in neuron-rich areas (pyriform and postcingulate cortex, hippocampus, and hypothalamic nuclei) and was mostly colocalized with neuron-specific enolase. In astrocytes, this mRNA was detected in the ependymal cell layer and the subependymal zone, and several isolated cells were also found in the brain parenchyma. We also detected TSH receptor mRNA and protein in primary cultured human astrocytes. The protein was detected as well in both rat and human brain cryoslices. Together, these findings clearly demonstrate the expression of the TSH receptor gene in the brain in both neuronal cells and astrocytes.

Direct role of plasma membrane-expressed gp120/41 in toxicity to human astrocytes induced by HIV-1-infected macrophages.

OBJECTIVE: To compare astrocyte toxicity induced by plasma membrane-expressed gp120/41 and soluble gp120. DESIGN: Analysis of morphological alterations and lactate dehydrogenase (LDH) release from astrocytes in culture with monocytes infected with HIV-1, microglia expressing Env of a macrophage-tropic HIV-1 isolate or soluble Env. METHODS: Primary human embryonic astrocytes were cultured with: monocytes infected with two M-tropic HIV-1 isolates (HIV-1(9533), HIV-1(BX08)); human microglia infected with the defective Semliki Forest virus (SFV) vector coding for the env gene of HIV-1(BX08) isolate (SFVenvBX08); and soluble gp140 purified from baby hamster kidney cells transfected with the env gene of HIV-1(BX08) lacking the intracytoplasmic region of gp41 (SFVdelta envBX08). Gp120 mRNA levels were assessed by quantitative reverse transcriptase-polymerase chain reaction and the protein was detected by immunofluorescence in infected monocytes or microglia. RESULTS: Contact of HIV-infected monocytes induced morphological changes in astrocytes and a 137% increase in LDH release at day 2 of co-culture compared with controls (uninfected monocytes). Gp120/41(BX08)-expressing microglia induced a 170% increase in LDH release (relative to SFVLacZ-infected microglia). Pretreatment of co-cultures with an anti-gp120 monoclonal antibody (mAb; NEA-9305) directed against the V3 loop inhibited LDH release. Soluble purified gp140 from BX08 isolate induced only a weak LDH release (104%). Finally, cytotoxicity was not blocked by treatment of the co-culture with Bordetella pertussis toxin, an inhibitor of Gi alpha protein-dependent receptors. CONCLUSION: HIV envelope glycoprotein expressed at the plasma membrane induced astrocyte damage more efficiently than its soluble counterpart. The V3 loop was involved in toxicity induction through a pathway independent of the Gi alpha protein-coupled receptor.

The nuclear receptor chicken ovalbumin upstream promoter transcription factor interacts with HIV-1 Tat and stimulates viral replication in human microglial cells.

Human immunodeficiency virus type 1 (HIV-1) infects the central nervous system and plays a direct role in the pathogenesis of AIDS dementia. However, the molecular mechanisms underlying HIV-1 expression in the central nervous system are poorly understood. We have recently reported that the nuclear receptor chicken ovalbumin upstream promoter transcription factor (COUP-TF), an orphan member of the nuclear receptor superfamily, is an activator of HIV-1 gene transcription. Here, our results show that COUP-TF stimulates HIV-1 transcription in primary cultured human microglial cells, the primary target for HIV-1 infection in brain. Run-on assays indicated that COUP-TF acts on the initiation step of transcription. Results from reverse transcription-polymerase chain reaction and immunocytochemistry analysis further revealed the importance of this factor by demonstrating that overexpression of COUP-TF leads to initiation of viral replication in primary HIV-infected human microglia. In addition, COUP-TF is able to physically interact and cooperate with the viral transactivator Tat. The combination of COUP-TF and Tat leads to NF-kappaB- and Sp1-independent enhanced transcriptional stimulation. In vitro binding studies showed that COUP-TF interacts with Tat through amino acids within the N-terminal DNA-binding domain of COUP-TF. Amino acids 48-72 in the basic and C-terminal regions of Tat are required for the binding of Tat to COUP-TF. These results suggest that COUP-TF is an essential transcription factor involved in HIV-1 expression in microglia and reveal a novel interplay of Tat and COUP-TF during regulation of viral expression.

Differences in kinetics of human cytomegalovirus cell-free viral release after in vitro infection of human microglial cells, astrocytes and monocyte-derived macrophages.

Microglial cells and astrocytes isolated from human embryonic proencephalon were compared to monocyte-derived macrophages (MDM) for their ability to replicate human cytomegalovirus (HCMV) in vitro. A specific cytopathic effect was observed in microglial cells and astrocytes, but not in MDM. A high percentage of glial cells but a low percentage of MDM expressed immediate-early and late viral antigens. The ability of HCMV-infected microglial cells and astrocytes to release viral particles in their supernatants was significantly higher than that of infected MDM. Human microglial cells and astrocytes at an early stage of development are highly susceptible to HCMV infection.

Neuronal apoptosis does not correlate with dementia in HIV infection but is related to microglial activation and axonal damage.

To characterize the distribution of apoptotic neurons and their relationships with the stage of disease, a history of HIV-dementia, and the degree of productive HIV infection, microglial activation and axonal damage, we examined the brains of 40 patients. Samples of frontal and temporal cortex, basal ganglia and brain stem were taken post-mortem from 20 patients with AIDS (including three with HIV-dementia, and eight with cognitive disorders that did not fulfil the criteria for HIV-dementia), 10 HIV-positive asymptomatic cases and 10 seronegative controls. Neuronal apoptosis was demonstrated by in situ end labelling in 18 AIDS cases and two pre-AIDS cases; a single apoptotic neuron was present in the temporal cortex of a control. Semiquantitative evaluation showed that the severity of neuronal apoptosis in the cerebral cortex correlated with the presence of cerebral atrophy, but not with a history of HIV dementia. There was no global quantitative correlation between neuronal apoptosis and HIV encephalitis or microglial activation. However, there was some topographical correlation between these changes. In the basal ganglia, apoptotic neurons were much more abundant in the vicinity of multinucleated giant cells and/or p24 expressing cells. Microglial activation was constantly present in these areas. Axonal damage was identified using beta-amyloid-precursor protein (betaAPP) immunostaining in 17 AIDS and eight pre-AIDS brains. Although no global quantitative correlation could be established between axonal damage and neuronal apoptosis there was an obvious topographic correlation supporting the view that axonal damage, either secondary to local microglial activation or due to the intervention of systemic factors, may also contribute to neuronal apoptosis.

Increased peroxynitrite activity in AIDS dementia complex: implications for the neuropathogenesis of HIV-1 infection.

Oxidative stress is suggested to be involved in several neurodegenerative diseases. One mechanism of oxidative damage is mediated by peroxynitrite, a neurotoxic reaction product of superoxide anion and nitric oxide. Expression of two cytokines and two key enzymes that are indicative of the presence of reactive oxygen intermediates and peroxynitrite was investigated in brain tissue of AIDS patients with and without AIDS dementia complex and HIV-seronegative controls. RNA expression of IL-1beta, IL-10, inducible nitric oxide synthase, and superoxide dismutase (SOD) was found to be significantly higher in demented compared with nondemented patients. Immunohistochemical analysis showed that SOD was expressed in CD68-positive microglial cells while inducible nitric oxide synthase was detected in glial fibrillary acidic protein (GFAP)-positive astrocytes and in equal amounts in microglial cells. Approximately 70% of the HIV p24-Ag-positive macrophages did express SOD, suggesting a direct HIV-induced intracellular event. HIV-1 infection of macrophages resulted in both increased superoxide anion production and elevated SOD mRNA levels, compared with uninfected macrophages. Finally, we show that nitrotyrosine, the footprint of peroxynitrite, was found more intense and frequent in brain sections of demented patients compared with nondemented patients. These results indicate that, as a result of simultaneous production of superoxide anion and nitric oxide, peroxynitrite may contribute to the neuropathogenesis of HIV-1 infection.

[Productive replication of human cytomegalovirus in primary microglial cells]. / Réplication productive du cytomégalovirus humain dans des cultures primaires de cellules microgliales.

Human cytomegalovirus (HCMV) infection can result in neurological symptoms. In vitro replication of the HCMV was studied in primary cultures of microglial cells from the central nervous systems (CNS) of human embryos. The microglial cells were infected with various amounts of either the AD169 laboratory HCMV strain or a clinical HCMV isolate. A specific cytopathic effect occurred within 24 h and persisted for two months. Immunocytochemical tests for immediate early and late viral antigens done one and three days after the infection demonstrated that 60% to 80% of the microglial cells were infected and that 3% to 8% were the site of viral DNA replication. Kinetic studies showed accumulation of viral particles in the supernatant during the first two weeks after the infection. Prestimulation of the cells by PMA 24 h before the infection was associated with increased release of viral particles and with an increased percentage of cells expressing late viral antigens. The microglial cells of the human embryonic CNS are fully permissive targets for the HCMV. The in vitro HCMV model used in this study may prove useful for investigating the pathophysiology of HCMV encephalitis, in particular after mother-to-fetus transmission of the virus.

Induction of human immunodeficiency virus type 1 replication in human glial cells after proinflammatory cytokines stimulation: effect of IFNgamma, IL1beta, and TNFalpha on differentiation and chemokine production in glial cells.

Although evidence for human immunodeficiency virus 1 (HIV-1) presence in the central nervous system (CNS) of infected patients is well established, the intensity of viral replication within the brain is not usually known. In vitro, human embryonic microglial cells internalized HIV-1 through a CD4-dependent pathway but were not permissive to viral replication. We observed that HIV replication was induced when CNS cell cultures were stimulated for 14 days by a combination of proinflammatory cytokines including IFNgamma, IL1beta, and TNFalpha. After long-term cytokine stimulation, morphologically differentiated glial cells appeared, in which HIV-1 tat antigen was detected after infection. Thus, variations in the stage of maturation/activation of CNS cells under inflammatory conditions probably play a major role in facilitating massive production of HIV-1. We then studied the effect of prolonged cytokine stimulation on the secretion of inflammatory mediators by glial cells. An early increased secretion of prostaglandin F2alpha and chemokines (RANTES>>MIP-1alpha>>MIP-1beta) was observed, due to both microglia and astrocytes. In contrast to persistent PGF2alpha production, an extinction of RANTES and MIP-1beta but not of MIP-1alpha secretion occurred during the 14 days of stimulation and was inversely correlated with the ability of glial cells to replicate HIV-1. The study of the secretory factors produced in response to a persistent inflammation could provide a better understanding of the modulation of HIV replication in glial cells.

Human immunodeficiency virus type 1 and its coat protein gp120 induce apoptosis and activate JNK and ERK mitogen-activated protein kinases in human neurons.

Detection of apoptotic neurons and microglial cells in the brains of human immunodeficiency virus type 1 (HIV-1)-infected patients has suggested that programmed cell death may be implicated in the physiopathology of HIV-1 encephalopathy. To analyze in vitro the intracellular signals induced by HIV-1 in human neurons and the associated neuronal death, we tested cultured human central nervous system (CNS) cells for apoptosis induced by HIV-1 and gp120 and for signaling pathways activated by gp120. HIV-1 and gp120 induced apoptosis of neurons and microglial cells but not of astrocytes or transformed microglial cells. Gp120 activated c-Jun N-terminal kinase (JNK) and p42 extracellular-regulated kinase (ERK) in primary CNS cells, with an early peak of activation at 2 to 5 minutes that was not present when pure microglial or astrocyte cultures were tested, followed by a late and sustained activation (10 and 60 minutes) in primary and enriched glial cell cultures as well as in transformed microglial cells. This demonstrates that gp120 could be an effector of HIV-1-induced apoptosis in the CNS and act directly on neuronal and glial cells.

[Neuronal apoptosis in the central and peripheral nervous system in HIV infection]. / Apoptose neuronale dans le système nerveux central et périphérique au cours de l'infection par le VIH.

Apart from the unique changes characteristic of "HIV encephalitis", the productive infection of central nervous system by HIV, which predominantly involves the white matter and basal ganglia, evidence is accumulating that the cerebral cortex may also be affected in AIDS patients. Neuronal loss, suspected at microscopic examination, has been demonstrated by a number of morphometric studies. However, the cause and mechanism of neuronal damage in HIV infection, are still unclear. In an attempt to look for an apoptotic process at the origin of neuronal loss in AIDS, we examined samples of frontal cortex, temporal cortex and basal ganglia from 12 patients who died from AIDS and 4 asymptomatic HIV-positive cases using in situ end labelling to demonstrate characteristic DNA fragmentation. These were compared with 5 asymptomatic seronegative controls, and 2 seronegative patients with Alzheimer's disease. We demonstrated neuronal apoptosis in all AIDS cases and in the Alzheimer's cases. Positive in situ end labelling was usually associated with morphological changes suggestive of neuronal apoptosis. Semiquantitative assessment of the density of apoptotic neurons showed that neuronal apoptosis was more severe in atrophic brains. In contrast, no correlation was found between the density of apoptotic neurons and the presence of HIV-encephalitis or a history of cognitive disorder. Only occasional apoptotic neurons were found in one asymptomatic, HIV-positive case. Apoptosis was never observed in asymptomatic seronegative cases. We also looked for apoptotic neurons in spinal ganglia of 20 AIDS cases, 5 of whom had a terminal sensory distal neuropathy, and 10 seronegative controls devoid of neuropathy. Apoptotic neurons were found in 6 of the AIDS patients and in none of the seronegative controls. However, no correlation was found between the severity of neuronal apoptosis in the spinal root ganglia and the presence of absence of a terminal distal sensory neuropathy. Experimental studies tend to support our in vivo findings. HIV-infection of primary cultures of human embryonic central nervous system induced frequent apoptosis of neurons. No apoptotic cell was identified in non infected control cultures.

[Neuronal apoptosis in the course of human immunodeficiency virus infection]. / Apoptose neuronale au cours de l'infection par le virus de l'immunodéficience humaine.

Apart from the unique changes characteristic of "HIV encephalitis", the productive infection of central nervous system by HIV, which involves predominantly the white matter and basal ganglia, evidence is accumulating that the cerebral cortex may also be affected in AIDS patients. Neuronal loss, suspected at microscopical examination, has been demonstrated by a number of morphometric studies. However, the cause and mechanism of neuronal damage in HIV infection, are still unclear. In an attempt to look for an apoptotic process at the origin of neuronal loss in AIDS, we examined samples of frontal cortex, temporal cortex and basal ganglia from 12 patients who died from AIDS and 4 HIV-positive asymptomatic cases using in situ end labelling to demonstrate characteristic DNA fragmentation. These were compared with 5 seronegative asymptomatic controls, and 2 seronegative patients with Alzheimer's disease. We demonstrated neuronal apoptosis in all the AIDS cases and in the Alzheimer's cases. Positive in situ end labelling was usually associated with morphological changes suggestive of neuronal apoptosis. Semiquantitative appreciation of the density of apoptotic neurons showed that neuronal apoptosis was more severe in atrophic brains. In contrast, no correlation was found between the density of apoptotic neurons and the presence of HIV encephalitis or a history of cognitive disorder. Only occasional apoptotic neurons were found in one asymptomatic, HIV-positive case. Apoptosis was never observed in asymptomatic seronegative cases. Experimental studies tend to support our in vivo findings. Infection by HIV of primary cultures of human embryonic central nervous system induced frequent apoptosis of neurons. No apoptotic cell was identified in non infected control cultures.

Adhesion to human neurons and astrocytes of monocytes: the role of interaction of CR3 and ICAM-1 and modulation by cytokines.

Monocytes but not unstimulated lymphocytes adhered to human neurons and astrocytes in primary culture, as demonstrated by double labeling. The expression of VCAM-1 was higher on neurons than on astrocytes, whereas that of beta 1, alpha 1, alpha 2, alpha 4 and alpha 5 chains from the integrins and of ICAM-1 was identical on both types of cells. The expression on neurons of ICAM-1, but not of integrins, was up-regulated by exogenous tumor necrosis factor (TNF) alpha, interleukin (IL)-1 alpha and interferon (IFN)-gamma. The same was observed on astrocytes associated with a sharp increase in the expression of VCAM-1. Adhesion between monocytes and neurons or astrocytes was 80% inhibited by mAbs directed against the CR3 determinant on monocytes or against ICAM-1 on neural cells but not by any of the other mAbs against adhesion proteins that were tested. Finally, the level of endogenous production of IL-1 alpha and TNF alpha was greatly increased after the adhesion of monocytes to CNS cells.

In vitro production of IL-6, IL-1 beta, and tumor necrosis factor-alpha by human embryonic microglial and neural cells.

The abilities of the different cells from human central nervous system (CNS) to produce IL-6, IL-1 beta, and TNF-alpha were tested in vitro using either cultures enriched in human embryonic microglial cells or primary cultures of human embryonic CNS cells. High amounts of IL-6, low amounts of IL-1 beta but no TNF-alpha were detected in supernatants of microglial cells, kept either in FCS-free conditions or in FCS-containing medium. Moreover, IL-6 mRNA was also present in 45 to 55% of microglial cells cultured in the presence of FCS as visualized by in situ hybridization, whereas IL-1 beta mRNA remained undetectable. After prestimulation of microglial cells with LPS or IL-1 alpha, the percentage of cells labeled with an antisense IL-6 mRNA probe increased to 70% and hybridization with an antisense IL-1 beta mRNA probe became detectable. In contrast to this dyscoordinate production of cytokines by microglial cells, human monocytes, freshly isolated from blood and kept in the same culture conditions, produced high levels of the three cytokines tested. In primary cultures of human embryonic CNS cells, IL-6, IL-1 beta, and TNF-alpha were produced mostly or only by microglial cells because no IL-1 beta mRNA or IL-6 mRNA were detected in astrocytes, even after prestimulation with LPS or IL-1 alpha. Finally, IL-1 was the main inducer of IL-6 production because IL-1 alpha, but not LPS, induced a significant increase in IL-6 synthesis in cultures kept in FCS-free medium. However, in presence of FCS, LPS appeared to initiate a cascade reaction involving the production of IL-1 by microglial cells, acting as an autocrine loop to trigger IL-6 synthesis.

Adhesion proteins on human microglial cells and modulation of their expression by IL1 alpha and TNF alpha.

Expression of adhesion proteins on human microglial cells was studied by immunocytochemistry. Both microglial cells and peripheral blood monocytes expressed beta 2 integrins and molecules of the immunoglobulin superfamily at similar levels whereas the expression of the beta 1 integrins (alpha 2-VLA (very late antigen), alpha 4-VLA, alpha 5-VLA, alpha 6-VLA) was higher on microglial cells than on monocytes. Stimulation of microglial cells with interleukin-1 alpha and tumour necrosis factor-alpha, the main cytokines detected in HIV1-infected central nervous system (CNS), increased the microglial expression of alpha 1-VLA, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and beta 2-LFA-1 (leukocyte-function-associated molecule-1) but not of alpha L-LFA-1. Such an induction of adhesion molecules could facilitate penetration of HIV1-infected monocytes into brain parenchyma and their adhesion to CNS cells, and could maintain a chronic inflammation during human immunodeficiency virus-1 (HIV1) encephalopathy.

Human immunodeficiency virus type 1-infected monocytic cells can destroy human neural cells after cell-to-cell adhesion.

Primary cultures of human embryonic neurons and astrocytes have been used to test the interactions between neural cells and either human immunodeficiency virus type 1 (HIV-1) or HIV-1-infected monocytes. After direct infection with HIV-1, neither morphological alteration of neurons and astrocytes nor signs of viral replication were observed. Similarly, cultured human neurons and astrocytes were resistant to incubation with the supernatant of HIV-1-infected U937 cells, a human monoblastoid cell line. In contrast, HIV-1-infected U937 monocytic cells adhered to neural cells and induced large plaques of necrosis surrounding them. This cytopathic effect began at the time of viral replication (day 16 after infection). Its intensity depended on that of viral replication, and its range was identical to the region of diffusion of viral antigens, as judged by immunocytochemistry. The cytopathic effect was not dependent on the release of free radicals. It could not be induced by cytokines or cytokine-stimulated U937 cells. It is likely that this cytopathic effect depends on the release of viral antigens either within the site of adherence itself or within close range of the astrocyte membrane.