Stavudine and the peripheral nerve in HIV-1 infected patients

Stavudine (2′,3′-didehydro-3′deoxythymidine) is a pyrimidine analogue that may be of great value in combination antiretroviral therapy (ART) for treating patients infected with human immunodeficiency virus type 1 (HIV-1). We assessed potential neurotoxic side effects by comparing peripheral nerve function in patients receiving ART including stavudine (n = 107) with that of patients receiving ART with zidovudine (n = 103). A cross-sectional analysis of electroneurographic data revealed no significant differences. In a follow-up examination of 31 patients newly started on ART with stavudine we observed no significant effects of the drug on electrophysiological measures. At a daily dose of 1.0 mg/kg the incidence of peripheral nervous system disease in our patients was about 10%. Repeated follow-up analysis of 13 patients on stavudine showed a significant reduction in sural nerve amplitude. Quantitative sensory testing in 13 patients revealed no systematic effect of stavudine on small nerve fibers. Peripheral nerve function in HIV-1 seropositive patients on ART with stavudine did not differ significantly from that in patients on ART with zidovudine. Therefore stavudine at a daily dose of 1.0 mg/kg is an alternative for patients who do not tolerate, or who have become resistant to zidovudine and can be recommended as a first-line drug in combination ART. Received: 31 March 1998 Received in revised form: 9 July 1998 Accepted: 19 August 1998     

Increasing intrathecal lymphocytosis and immunoglobulin G production in neurologically asymptomatic HIV-1 infection

Cerebrospinal fluid from 34 human immunodeficiency virus (HIV-1) seropositive patients, only four of whom had HIV-related neurological symptoms, was examined by cytology, protein quantification, isoelectric focusing and specific serological tests. CSF lymphocytosis and evidence of intrathecal IgG production, found in 21 and 20 respectively of the 34 patients, correlated significantly with the duration of the infection. Increasing IgG index was found in two patients with repeated CSF examinations during greater than 7 years. Intrathecal HIV antibodies were detected on Western blot in 32/34 patients. HIV antigen test positive in 5/34 sera was negative in all 34 CSF samples. Intrathecal B cell activation seems to increase during the early HIV infection.     

Action (verb) generation in HIV-1 infection

It has been proposed that verb generation is primarily associated with left fronto-basal ganglia circuits, whereas the generation of nouns is principally mediated by dominant left temporo-parietal networks. Consistent with this premise, action (verb) fluency - a verbal fluency task requiring the spontaneous generation of verbs - has shown greater sensitivity to frontal-basal ganglia pathophysiology (e.g., dementia in Parkinson's disease (PDD)) than noun fluency. The present study examined action and noun fluency in persons with HIV-1 infection-a disease known to be associated with a frontal-basal ganglia circuit neuropathogenesis. Action and noun ("animals") verbal fluency protocols were administered to 97 persons with HIV-1 infection and 20 demographically comparable healthy comparison (HC) subjects. A significant interaction emerged between verbal fluency task and HIV-1 serostatus such that the HIV+ group generated significantly fewer actions (verbs) relative to the HC sample. Findings indicate that persons infected with HIV-1 experience difficulty rapidly generating verbs, but not nouns from semantic memory. Considering the prominent frontal-basal ganglia circuit neuropathophysiology of HIV-1 infection, these data are consistent with the hypothesized dissociation between noun and verb generation as pertains to generative fluency.     

Morphine amplifies HIV-1 expression in chronically infected promonocytes cocultured with human brain cells

Previous studies have shown that morphine promotes the replication of human immunodeficiency virus (HIV)-1 in peripheral blood mononuclear cell cocultures. In the present study, we tested the hypothesis that morphine would amplify HIV-1 expression in the chronically infected promonocytic clone U1 when cocultured with lipopolysaccharide-stimulated human fetal brain cells. Marked upregulation of HIV-1 expression was observed in these cocultures (quantified by measurement of HIV-1 p24 antigen levels in supernatants), and treatment of brain cells with morphine resulted in a bell-shaped dose-dependent enhancement of viral expression. The mechanism of morphine's amplifying effect appears to be opioid receptor-mediated and to involve enhanced production of tumor necrosis factor-α by microglial cells.     

Simultaneous detection of ferritin and HIV-1 in reactive microglia

Summary Using ferritin as a marker of reactive microglia, we demonstrated a close association between proliferation of reactive microglia and expression of human immunodeficiency virus type 1 (HIV-1) in brain tissue from autopsied cases of acquired immunodeficiency syndrome (AIDS). An increased number of ferritin-positive reactive microglia was observed in formalin-fixed paraffin-embedded brain sections from all 13 AIDS cases examined. Similar findings were observed in brain tissue from other neurological diseases (subacute sclerosing penencephalitis, herpes simplex encephalitis and multiple sclerosis). Multinucleated giant cells were found in 7 of the AIDS cases which were also intensely labeled for ferritin. Dual-label immunohistochemistry using anti-ferritin and cell-specific markers showed that ferritin-positive cells were distinct from astrocytes, neurons and endothelia using anti-glial fibrillary acidic protein (anti-GFAP), anti-neurofilament protein and Ulex europaeus agglutinin 1, respectively. In 5 AIDS brains, only ferritin-positive cells were shown to contain HIV-1 gp41 antigen using dual-label immunohistochemistry. In addition, HIV-1 RNA was localized in territin-positive reactive microglia but not in GFAP-positive astrocytes using immunohistochemistry combined with in situ hybridization. Ferritin-positive reactive microglia and multinucleated giant cells were colabeled with the microglial marker, Ricinus communis agglutinin 1 (RCA-1). Howerver, RCA-1 also extensively stained resting microglia only a few of which were colabeled for ferritin. The density of ferritin-positive cells was correlated with the presence of HIV-1 RNA-positive cells in AIDS brain. Thus, ferritin immunoreactivity can be used as an activation marker of microglia in archival paraffin sections and reflects the extent of inflammation in HIV-1-infected brain.Supported in part by NIH Grants RO1 DA04787, RO1 HD26621, PO1 NS25569, the Biopsychosocial Center for the Study of AIDS (NIMH P50 MH 43455), the Department of Veterans Affairs, the Mary Jane Crowe Foundation, the Swedish Society of Medicine (Stockholm, Sweden), and the Multiple Sclerosis Society of Göteborg (Göteborg, Sweden)     

M-CSF production by HIV-1-infected monocytes and its intrathecal synthesis implications for neurological HIV-1-related disease

Macrophage-colony stimulating factor (M-CSF) is detectable in the cerebrospinal fluid (SF) of HIV-1-infected patients, and may be produced intrathecally by both reactive astrocytes and cells of the monocyte/macrophage (MO) lineage, microglial cells included. Since MO constitute the target cells for HIV-1 in the central nervous system (CNS), the culture conditions that induce M-CSF production by HIV-1-infected MO were studied. MO cultures infected with supernatants (SN) of HIV-1-infected peripheral blood lymphocyte (PBL) cultures produced only trace or undetectable amounts of M-CSF. Co-cultures of MO with normal PBL released high amounts of M-CSF, suggesting that viable cell-to-cell interactions are required to induce cytokine production by MO and/or PBL. M-CSF production was markedly increased in the MO co-cultured with HIV-1-infected PBL, thus implying that HIV-1 induces increased cytokine synthesis/release by MO and/or PBL only when cell membrane-associated messages are operating. Intracerebrally synthesized M-CSF by HIV-1-infected MO may play a role in promoting viral replication/spread within the CNS, and inducing brain damage by stimulating microglia proliferation, and neurotoxic factor release by these cells.     

Central nervous system lesions in rats infected with Friend murine leukemia virus-related PVC441: ultrastructural and immunohistochemical studies

Newborn F344 rats were injected intraperitoneally with PVC441 virus, a neuropathogenic variant of Friend murine leukemia virus, and developed paraparesis of hind limbs 35–40 days after infection. Immunohistochemical study using monoclonal anti-PVC441 antibody revealed that in the central nervous system endothelial cells but not neuronal or glial cells were infected with PVC441 virus. The major pathological changes were myelin vacuolation and oligodendrocyte degeneration in the white matter at the white-gray border zone. Anterior and lateral funiculi and intercalated myelin of anterior horns were dominantly affected in the spinal cord from the sacral to cervical level. The midbrain was also vacuolated. An ultrastructural study demonstrated that many viral particles were present outside the endothelial cells but only sparsely inside endothelial cells and pericytes. Endothelial cell membranes and tight junctions were also disrupted. Immunohistochemical studies with antibodies against major histocompatibility complex class Ia, intercellular adhesion molecule-I, glial fibrillary acidic protein, neurofilament protein, CD3 and OX42 revealed the presence of abundant microglia but not of lymphocytes or polymorphonuclear cells in the lesions. Axonal degeneration and astrogliosis were mild in degree. These pathological changes explain the observed spastic paraparesis in the rats, and represent a good model of spongiform diseases of the human central nervous system of retroviral origin, such as human T cell leukemia virus-associated myelopathy and AIDS. Received: 4 March 1996 / Revised, accepted: 8 October 1996     

Investigation on the expression of major histocompatibility complex class II and cytokines and detection of HIV-1 DNA within brains of asymptomatic and symptomatic HIV-1-positive patients

Among the various mechanisms proposed to explain the pathogenesis of cerebral lesions in human immunodeficiency virus (HIV)-induced encephalitis, a cytokine-mediated action has found most favour. Indeed, elevated expression of cytokines such as interleukin (IL)-1 and tumour necrosis factor-α (TNF-α), thought to be neurotoxic, has been found in AIDS patients. As a previous study had demonstrated the presence of HIV proviral DNA in brain tissue of a number of HIV-positive non-AIDS patients, we undertook this present investigation using morphological, immunohistochemistry (IHC) and polymerase chain reaction (PCR) methods to detect the expression of major histocompatibility complex (MHC) class II molecules, the presence of HIV-1 proviral DNA and of the cytokines TNF-α, IL-1α, IL-4 and IL-6 in brains of the same group of individuals. The study included brains of 36 asymptomatic HIV-1 positive patients and the results were compared with those of AIDS patients either affected by HIV encephalitis (n = 8) or exempt from any neuropathological changes (n = 10) as well as of normal controls (n = 5). Results show that: HIV proviral DNA could be detected by PCR in 17 out of the 36 brains from HIV-positive pre-AIDS cases; most (15 of 17) of PCR-positive brains showed minimal to severe expression of MHC class II antigen; and cytokines could be detected predominantly within white matter even at this early stage. The data demonstrated that the state of immune activation described in AIDS is already present at the pre-AIDS stage and suggest that the presence of cytokines may already trigger the cascade of events leading to brain damage. Received: 7 August 1995 / Revised, accepted: 20 October 1995     

Microglial cell upregulation of HIV-1 expression in the chronically infected promonocytic cell line U1: the role of tumor necrosis factor-α

Culture supernatants from lipopolysaccharide (LPS)-treated murine microglial cells were found to markedly induce the expression of human immunodeficiency virus (HIV)-1 in the chronically infected human promonocytic cell line U1 as detected by measurements of HIV-1 p24 antigen release into U1 culture supernatants. Antibody to tumor necrosis factor (TNF)-α had an inhibitory effect on the induction of virus by microglial cell supernatants. Also, treatment of microglia with pentoxifylline, an inhibitor of TNF-α production, resulted in suppressed amounts of TNF in the supernatants of LPS-treated microglia and in a reduced stimulatory capacity of these supernatants on HIV-1 expression in U1 cells. These findings support the concept that TNF-α production by glial cells plays a pathogenetic role in HIV-1-associated brain disease by promoting the expression of the virus in infected cells.     

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.     

Degeneration of the cerebellar dentate nucleus and the inferior olivary nuclei in HIV-1-infected brains: a morphometric analysis

Motor dysfunction is frequently noted in human immunodeficiency virus type 1 (HIV-1)-infected patients. Until recently, neuropathological changes found in the basal ganglia were advanced as pathogenetic mechanisms. In the present study, further brain structures involved in motor control were analyzed morphometrically. The volume density, numerical density, and the size of neurons in the cerebellar dentate nucleus and in both inferior olivary nuclei were determined. In both regions of HIV-1-infected brains, a significant reduction in the volume density, the numerical density of neurons and neuronal size was apparent. The morphometric data from the present study disclose involvement of both types of nuclei investigated during the course of HIV-1 infection, and might constitute a possible morphological substrate for the motor dysfunction seen in HIV-1-infected patients. Received: 22 February 1995 / Revised: 15 December 1995 / Accepted: 26 February 1996     

HIV-1 non-specifically stimulates production of transforming growth factor-β1 transfer in primary astrocytes

HIV-1 expression in monocytes/macrophages can be controlled by transforming growth factor-beta l (TGF-β1). TGF-β1 is present in astrocytes surrounding HIV-1-infected monocyte/macrophages in brain tissue from patients with AIDS but not from seronegative, normal individuals. We sought to determine whether or not production of TGF-β1 can be directly stimulated by HIV-1 in astrocytes. Astrocytes from neonatal rat cortex grown in primary culture were exposed to HIV-1 virions for 24 h. One day later, TGF-β1 was measured in culture supernatants by a biological assay. HIV-1 caused 1.7-2.1-fold increase in extracellular concentration of TGF-β1. TGF-β1 production also was stimulated by recombinant HIV-1 proteins gp120, p66 and p24. Gpl20 labeled with fluorescein was visualized inside astrocytes and its stimulatory effect was not blocked by antibodies against rat CD4. The effect was not specific to HIV-1 and its proteins, because non-opsonized Latex particles and leucine methyl ester (LME) (known to be phagocytosed and endocytosed, respectively, by astrocytes) also stimulated TGF-β1 production. The effect was inhibited by two inhibitors of the phago/endocytotic pathway, chloroquine and leupeptin. These results may be relevant to the neuropathogenesis of HIV-1 infection.     

Expression of caspase-3 in brains from paediatric patients with HIV-1 encephalitis

Apoptosis of neurones, macrophages, and microglia occurs in the brains of paediatric patients with human immunodeficiency virus (HIV) type 1 encephalitis, which is often associated with pre-mortem neurological disease (progressive encephalopathy). We have previously reported that TUNEL-positive neurones in brain tissue from paediatric patients with HIV type 1 encephalitis and progressive encephalopathy are strikingly devoid of the pro-apoptotic gene product Bax, in marked contrast to brain-resident macrophages and microglia. Using immunocytochemical methods, the present study demonstrate that neurones in patients with HIV type 1 encephalitis and progressive encephalopathy, as well as macrophages and microglia, but not astrocytes, overexpress caspase-3, a pro-apoptotic enzyme that is proteolytically activated downstream of Bax-Bcl-2 dysregulation. Co-localization of neuronal cytoplasmic caspase-3 and nuclear TUNEL staining, a marker for fragmented DNA, was also infrequently observed in brain tissue from patients with HIV type 1 encephalitis and progressive encephalopathy. These findings suggest that vulnerable neurones in brain tissue from patients with HIV virus type 1 encephalitis and progressive encephalopathy undergo apoptosis by a mechanism that involves upregulation of caspase-3 in a pathway that is independent of Bax-Bcl-2 dysregulation. Furthermore, caspase-3 upregulation in apoptotic neurones likely occurs prior to DNA fragmentation.     

Muscle disease,HIV and zidovudine: the spectrum of muscle disease in HIV-infected individuals treated with zidovudine

Eleven patients with AIDS or AIDS-related complex who developed muscle-related symptoms whilst taking zidovudine were investigated. The clinical details of a further ten patients who did not undergo muscle biopsy are also outlined. The clinical features, quantitative muscle strength testing, electromyographic findings, serial creatine kinase levels, muscle biopsy appearance on light microscopy and the effects of zidovudine withdrawal and rechallenge are described. The spectrum of muscle disease encountered included four cases of frank myopathy diagnosed using clinical, electrophysiological and histological criteria, four patients with mild weakness and myalgia in whom muscle biopsies were normal, three patients with myalgia only and a mild increase in the interstitial cell infiltrate shown by biopsy. The patients presenting with myopathy showed no improvement on withdrawal of zidovudine but responded to immuno-suppressive therapy with steroids and, in one case, thalidomide prescribed incidentally. At present, it is not yet possible to clinically define a specific zidovudine-induced myopathy that is distinct from the other effects of HIV infection on muscle structure and function. Our experience suggests that zidovudine may be implicated as a myotoxin in some patients, particularly those with myalgia and mild weakness. In those patients with severe weakness, and with biopsy findings of necrosis and inflammation, the drug effects may be difficult to separate from the primary effects of HIV.     

Mitochondrial DNA levels in the brain of HIV-positive patients after zidovudine therapy

Previous studies have shown that the antiviral nucleoside analogue zidovudine (AZT) depletes levels of mitochondrial DNA (mtDNA) in muscle of patients on long-term therapy. In this study we found that in a similar group of eight HIV-positive patients receiving AZT there was no depletion of brain mtDNA. This finding suggests that AZT related mtDNA depletion is not a contributing factor in the HIV encephalopathy that occurs in a proportion of HIV positive patients receiving this antiviral agent.     

An initial screening for HIV-associated neurocognitive disorders of HIV-1 infected patients in China

HIV-associated neurocognitive disorders (HAND), characterized by cognitive, motor, and behavioral abnormalities, are common among people living with HIV and AIDS. In combined antiretroviral therapy era in Western countries, nearly 40% of HIV-infected patients continue to suffer from HAND, mainly with mild or asymptomatic cognitive impairment. However, the prevalence and the clinical features of HAND in China are still not well known. In this study, a multi-center cross-sectional study was performed to determine the prevalence and clinical features of HAND in 134 HIV-1 infected patients in China. The International HIV Dementia Scale and a neuropsychological test battery were administered for screening and diagnosis HAND. Subjective complaints, CD4 count and viral loads in both blood plasma and cerebrospinal fluid were correlated with diagnosis of HAND. The results showed that the prevalence of HAND was approximately 37% in these patients. CD4 counts at time of sampling were significant lower in the HAND group than in the non-HAND group. But the distribution of the HAND severity did not differ by CD4 count or viral load. The presence of HAND was associated with cognitive and behavior disorder complaints (4.9- and 4.1-fold higher than those without HAND, respectively). The present data suggest that CD4 count and viral load cannot predict the severity of HAND, although the prevalence of HAND is similar to previous report in these patients. Cognitive and behavioral disorder is major complaint rather than cognitive and motor impairment. A larger prospective study is needed to obtain better estimates of HAND in China.     

Wernicke's encephalopathy in two patients with acquired immunodeficiency syndrome

Summary Two non-alcoholic homosexual patients with acquired immunodeficiency syndrome (AIDS) are reported who developed acute Wernicke's encephalopathy in the terminal stage of their illness. The first patient presented with vascular congestion, minute haemorrhages, proliferation of microglia and of the vessel walls at the predilection sites of the Wernicke-Korsakoff process. In the second patient only the mamillary bodies were involved. Besides Wernicke's encephalopathy, a primary cerebral immunoblastoma and cerebral toxoplasmosis were found in the first patient, whereas the second showed severe encephalitis with numerous microglial and multi-nucleated giant cells reacting positively with anti-HIV antibody. Just as in the development of Wernicke's encephalopathy in malignant diseases, the catabolic trend of the metabolism of the immunodeficient patients with consecutive thiamine deficiency must be considered the principal pathogenetic mechanism.     

Development of a platelet-activating factor antagonist for HIV-1 associated neurocognitive disorders

The neuroregulatory activities of PMS-601, a platelet activating factor antagonist, were investigated in laboratory and animal models of HIV-1 encephalitis (HIVE). For the former, PMS-601 reduced monocyte-derived macrophage pro-inflammatory secretions, multinucleated giant cell (MGC) formation, and neuronal loss independent of antiretroviral responses. PMS-601 treatment of HIVE severe combined immunodeficient mice showed reduced microgliosis, MGCs and neurodegeneration. These observations support the further development of PMS-601 as an adjunctive therapy for HIV-1 associated neurocognitive disorders.     

Acute polyradiculopathies in HIV-infected patients

We studied 17 consecutive cases of acute polyradiculopathy (PR) diagnosed in HIV-infected patients to investigate the possible causes of this syndrome in our milieu. Sixteen patients presented with lumbosacral PR and one patient had predominantly cervical PR. Electrophysiological study showed a predominantly motor axonal neuropathy in all patients examined. Six patients had a laboratory-confirmed aetiology for the PR: cytomegalovirus (CMV) was isolated from cerebrospinal fluid (CSF) in three cases, meningeal lymphomatosis was diagnosed by CSF cytology in two cases, and one patient had cryptococcal meningitis. Another patient was thought to have acute axonal polyradiculoneuritis associated with HIV infection. CMV and Mycobacterium tuberculosis were the probable agents in four and three patients, respectively. Finally, in three patients a cause could not be established. Both ganciclovir and foscarnet were effective in the treatment of definite or probable CMV PR. The present study confirms that acute lumbosacral PR in HIV-infected patients must be considered a syndrome with different causes. CMV and M. tuberculosis infections were the most frequent causative agents in our series (41% and 18% of the cases, respectively). Early empirical therapy is often necessary as definite diagnosis may be delayed or never achieved. Our experience suggests that, at least in our milieu, antituberculous drugs should be considered in some cases together with ganciclovir or foscarnet in the empirical therapy for PR in HIV-infected patients. Received: 14 April 1997 / Accepted: 6 June 1997