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Year : 2007  |  Volume : 10  |  Issue : 2  |  Page : 69-80

Changing patterns of human immunodeficiency virus-associated neuropathology

1 Service Central d'Anatomie et Cytologie Pathologiques, AP-HP Hôpital Lariboisière, Université Paris VII, France
2 Institute of Neurology, UCL, London, United Kingdom
3 Center for Sexual Health and HIV Research, Department of Primary Care and Population Sciences, UCL and Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1, United Kingdom

Correspondence Address:
Francesco Scaravilli
Institute of Neurology, UCL, London
United Kingdom
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-2327.33213

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This paper describes the evolution of the pathogenic concepts associated with the infection by the human immunodeficiency virus (HIV), with emphasis to the pathology of the nervous system. Although the first description of damage to the nervous system in the acquired immunodeficiency syndrome (AIDS) only appeared in 1982, the dramatic diffusion of the epidemic worldwide, as well as the invariably rapidly fatal outcome of the disease before the introduction of efficient treatment, generated from the beginning an enormous amount of research and re-thinking on a number of pathogenetic concepts. Less than 25 years after the first autopsy series on AIDS patients were published and the virus responsible for AIDS was identified, satisfactory definition and classification of a number of neuropathological complications of HIV infection have been established. This has led to the establishment of accurate clinical and biological diagnosis of the main neurological complications of the disease, which remain a major cause of disability and death in patients. Clinical and experimental studies have provided essential insight into the pathogenesis of CNS lesions and the natural history of the disorder. The relatively recent introduction of effective antiretroviral therapy in 1995-6 dramatically improved the course of prognosis of HIV disease. However, there remain a number of unsolved pathogenetic issues, the most puzzling of which remains the precise mechanism of neuronal damage underlying the specific HIV-related cognitive disorder (HIV-dementia). In addition, although antiretroviral therapy has changed the course of neurological complications, new issues have emerged, such as the lack of improvement or even paradoxical deterioration of the neurological status in treated patients. Interpretation of these complications remains largely speculative, partly because of the small number of neuropathological studies related to the beneficial consequence of this treatment.

Keywords: Acquired immunodeficiency syndrome, highly active antiretroviral therapy, history of diseases, human immunodeficiency virus (HIV), HIV dementia, neuropathology, pathogenesis

How to cite this article:
Gray F, Scaravilli F, Miller RF. Changing patterns of human immunodeficiency virus-associated neuropathology. Ann Indian Acad Neurol 2007;10:69-80

How to cite this URL:
Gray F, Scaravilli F, Miller RF. Changing patterns of human immunodeficiency virus-associated neuropathology. Ann Indian Acad Neurol [serial online] 2007 [cited 2022 Jun 27];10:69-80. Available from:

   Introduction Top

Involvement of the central nervous system (CNS) in the acquired immunodeficiency syndrome (AIDS) is a relatively recent event, which has generated an enormous amount of clinical and experimental research because of the dramatic worldwide spread of the epidemic involving over 30 million individuals[1],[2],[3] and its dire consequences.

The early eighties saw the appearance, initially in the USA, of a new "epidemics" of Kaposi sarcomas and unusual opportunistic infections in the gay community and Haitians.[4] The new disorder, referred to as "acquired immunodeficiency syndrome" (AIDS) with T-cell depletion, was considered to be induced by a virus. Originally known as "lymphadenopathy associated virus" (LAV)[5] or "human T cell lymphotropic virus type III" (HTLV-III),[6] it was finally named by consensus "human immunodeficiency virus" (HIV).

As the nervous system takes a major part as a cause of disability and death in AIDS patients,[7] a huge amount of post-mortem work tried to establish the spectrum of HIV damage.[8],[9] Additional work led to define the pathogenesis of cerebral damage and the natural history of CNS involvement, particularly in the early stages of the infection.

Unfortunately, not all the issues could be solved; these include the stage of the infection at which HIV enters the central nervous system and the precise mechanism of neuronal damage underlying the specific HIV-related cognitive disorder (HIV dementia); in addition, complications have emerged recently, following the introduction of therapeutic drugs.

The human immunodeficiency virus (HIV)

The discovery of the human immune deficiency virus - HIV-1[5],[10] was followed, a few years later, by that of a second virus, HIV-2, found in West Africa. Both are RNA viruses belonging to the lentivirus group of the retrovirus family.[11] HIV is a non transforming virus, which replicates through the generation of a proviral DNA intermediate by the action of a retroviral enzyme RNA-directed DNA polymerase (reverse transcriptase - RT). In vivo, a persistent infection follows integration of proviral DNA into the host genome.

As similar diseases affected macaques in primate centres in the USA and elsewhere,[12] it soon became apparent that these viruses had first been acquired, about a century ago, from non-human primates.[13],[14],[15]

To enter cells, retroviruses must bind to a specific cellular receptor located on the surface of CD4 cells;[16] they productively infect T-lymphocytes in vitro[17] as well as cells of the monocyte/macrophage lineage.[18],[19] Co-receptors too are involved in facilitating the infection; they include the chemokine receptors CXCR4[20] and CCR5.[21] Eventually, presence of HIV within a cell results in one of the following conditions: 1) productive infection; 2) latent infection, a situation in which the DNA provirus is blocked at the stage of transcription; 3) non-productive (or restricted) infection, in which the unintegrated or integrated viral DNA does not result in viral production.

The continuous evolution of HIV in vivo has important implications with regard to its replication[22] and its cytopathic effects.[22]

After the gay community, HIV infection soon spread to other groups, including intravenous drug users, patients receiving blood transfusion and organ transplants, women undergoing artificial insemination and children born to HIV-positive parents or breast fed by positive women. Although the heterosexual route of infection was well known from the outset, lately it has become the predominant form of infection, particularly in sub-Saharan regions.

Definition and classification of the multiple neuropathological complications of HIV infection

The severe deficit of cell-mediated immunity makes AIDS patients prone to infections of virtually any organ in the body by a wide range of opportunistic organisms including viruses, bacteria, fungi and protozoa. In addition, patients may develop tumours, the most common of which are non-Hodgkin's lymphomas and Kaposi's sarcoma.[23]

Among the viruses, cytomegalovirus was present in between 10%[24] and 30%[25] of the patients. Progressive multifocal leukoencephalopathy (PML), a previously rare viral encephalitis, due to a papovavirus, has an incidence varying between 2%,[26] 5%[27],[28] and 7%.[24] Cryptococcosis, the commonest mycosis in AIDS, presents predominantly as meningitis[29] and was identified in 3-8% of the cases.[26],[28] Toxoplasmosis became the commonest cause of intracerebral mass lesion, with a larger incidence in Europe[24],[30],[31] than in America.[26],[32],[33]

Lymphomas, either primary or secondary, are common in AIDS; they are usually high grade, non-Hodgkin and appear as multiple and partly necrotic masses. Histologically they consist of B-cell immunoblasts. A relationship with viruses, already found in patients undergoing transplants,[34] was confirmed in AIDS patients, all of whom proved serologically positive to Epstein-Barr virus.[35],[36]

An early paper[7] conveyed the impression that opportunistic organisms were also the cause of a subacute form of encephalitis, characterised by "subtle cognitive changes accompanied by malaise, lethargy….". However, its close relationship with HIV was confirmed by viral detection within the nerve tissue,[37] together with the finding of multinucleated giant cells (MGC)[38] [Figure - 1]a, the hallmark of the syndrome.[39] These result from virus-induced fusion of infected macrophages, thus reflecting both productive infection and the pathogenic role for the virus. MGC [Figure - 1]b, together with microglia, are seen to contain HIV protein. Further observations revealed 3 types of changes in HIV infected patients, in the absence of any other cause; these can be variably associated:

  1. HIV encephalitis (HIVE) [Figure - 2]a, characterised by disseminated foci or more diffuse lesions including myelin loss, astrogliosis and microglial activation with microglial nodules, macrophages and MGC. The viral load is high.
  2. HIV leukoencephalopathy (HIVL-lep) [Figure - 2]b, shows diffuse myelin pallor, particularly severe in the centrum semiovale. It is frequently associated with HIVE. Both types may represent the extremes of a spectrum and may overlap in one third of cases.[40] Widespread axonal damage identified by immunocytochemistry of beta-amyloid protein precursor [Figure - 3]a was also shown to be extremely frequent in AIDS.[41] Abnormality of the brain microvasculature[42],[43] leads to brain-blood-barrier (BBB) damage, in turn responsible for the diffuse myelin pallor.[44] This was recently confirmed by loss of tight junction protein, zonula occludens-1, in patients with HIV dementia.[45] This topic is reviewed by Petito and Cask.[46]
  3. A less obvious involvement of the grey matter is also frequent in AIDS. In its extreme form it has been defined as "diffuse poliodystrophy" [Figure - 2]c, characterized by diffuse astrogliosis and microglial activation and observed in about half of AIDS patients.[27],[47] Neuronal loss, suspected at microscopy, was confirmed by several morphometric studies.[48] Later, neuronal damage in AIDS was correlated, at least in part, with apoptosis[49],[50],[51] [Figure - 3]b.

HIV infection affects also children born to HIV-positive parents. Of the 3 million children infected, 50% have already died of AIDS. Sub-Saharan Africa is at present the area with the highest incidence, approximately 1000 new cases every day. Neurological complications in children, more common than in adults,[52],[53] consist of delayed or arrested development, microcephaly, progressive ataxia and cortico-spinal tract signs. Pathological changes[54] include vascular mineralization in 92%, white matter changes (78%) with inflammatory infiltrates (75%), MGC (36%) and vascular inflammation (30%). Recently, Gelbard et al[55] confirmed the presence of neuronal apoptosis. On the other hand, opportunistic infections have a lower incidence (14%).

Despite an overall similarity in the natural history of HIV infection in all the various risk groups (see above), some differences were observed: among the haemophiliacs, there is low prevalence of opportunistic infections and high rate of death from intracranial haemorrhage and liver cirrhosis.[56] Similarly, the incidence of opportunistic infections is lower in drug users than in homosexuals, despite similar CD4 counts.[57]

For a number of clinico-pathologic conditions in HIV infection, no plausible pathogenesis has been found. Among these, vacuolar myelopathy (VM) ,[7],[58] appears late in the course of the infection and represents the single most common spinal disorder in AIDS, with range from 1[27] to 55%.[59] It is rare in children.[60] Changes[61] include intramyelinic and periaxonal vacuoles, some containing macrophages, predominantly within the lateral and posterior columns, though not limited to any specific tract. In a clinical and pathological study, VM was noted[62] to start at mid-low thoracic level with rostral and caudal spreading with increasing severity.

Both the association of VM with HIVE and a number of pathological findings[63],[64] suggest a direct role by HIV. However, VM was found in non-AIDS immunocompromized patients.[65] Despite similarities with subacute combined degeneration (SCD), the role of vitamin B 12 deficiency was not substantiated. Another possibility is that persistent immune activation in the CNS may lead to local production of myelin or membrane damaging cytokines, such as TNF-α,[66] toxins or oxygen radicals. Degenerating myelin may attract macrophages; those expressing gp-120 may further cause a functional disorder of oligodendrocytes and thus could underlie the diffuse myelin loss seen in HIV encephalopathy.[67] Such macrophages may be activated to secrete cytokines or attempt to phagocytose myelin.

A further rare, complication of HIV infection is vasculitis, appearing as lymphocytic[68] or granulomatous[69] infiltration of the walls of cerebral vessels with or without accompanying necrosis and sometimes associated with meningitis.[70] Its exact relationship with HIV infection remains obscure.

Pathogenesis of CNS changes in HIV infection

Three issues appear relevant for the understanding of the pathogenesis of the CNS changes during HIV infection: 1) the types of cells harbouring HIV, 2) the pathogenesis of neuronal damage and 3) the time of arrival of HIV into the CNS.

1) Microglial cells and macrophages are the target for HIV[18],[19] and several studies suggest the role of 'Trojan horse' for HIV-infected monocytes in the dissemination of infectious particles. As for a possible role of neuroectodermal cells, various groups have found evidence of HIV infection in astrocytes[71],[72],[73],[74] and oligodendrocytes.[71] Moreover, demonstrable HIV-DNA and RNA in glial cells were found in all HIV-positive demented patients, but in only few non demented.[71] Cerebral endothelial cells too appear infected.[15],[71] As for nerve cells, HIV-1-DNA was detected by Nuovo et al[75] and Bagasra et al ,[76] but not by others.[71],[77] However, it appears that, in all cell types, HIV manages to establish a persistent, rather than productive, infection and that only in microglial cells and monocytes, it establishes a productive infection.[78]

Pathogenesis of neuronal damage

Therefore, an indirect mechanism of neuronal damage, as the basis of the cognitive disorder (see below), is considered more likely. This can be achieved via virus- and glial cell-derived proteins;[79] the following neurotoxic factors, possibly acting in combination,[80] have been incriminated: viral proteins, particularly gp120 , gp41 , tat , nef or substances produced by activated glial and microglial cells such as cytokines, prostaglandins, proteases, arachidonic acid or quinolinic acid metabolites.[48] In particular, viral proteins, such as tat , can cause neurotoxic damage at remote sites[81] by being transported along neural pathways. A glutamate-mediated excitotoxicity has been supported by in vitro studies,[82],[83],[84] as increased glutamate levels are found in the CSF and plasma of patients with HIV-related dementia.[85] Increased levels of quinolinic acid, a glutamate agonist, are present in the CSF of AIDS patients with cognitive and motor abnormalities.[86] In addition, activated microglial cells may express the high affinity glutamate transporter "excito-amino acid transporter -1" (EAAT-1), whilst its normal expression by astrocytes is inhibited.[87],[88]

It has been shown that a combination of toxins with cellular and viral factors induces a more severe degree of neuronal apoptosis that each of them in isolation.[89] This has led to the suggestion that neuronal damage in HIV infection may be multifactorial.[90] The mechanism of the irreversible neuronal DNA damage and eventual apoptosis appears to involve oxidative stress and glutamate-receptor-mediated toxicity.[80] In vitro studies have suggested that combined HIV protein and cytokine neurotoxicity may be mediated by oxidative stress[91] and cause neuronal apoptosis.[92] It was also shown, in vivo , that peroxinitrite activity resulting from the simultaneous production of super oxide anion and nitric oxide is significantly increased in demented, compared to non-demented, AIDS patients.[93] Finally, Nath et al[94] have suggested that neurotoxic proteins can initiate a cascade of events that self-perpetuate in a positive feedback manner. The topic is reviewed and discussed by Li et al .[95]

Time of arrival of HIV into the CNS

A late arrival of the virus into the CNS would allow early treatment to prevent infection entering the CNS, thus potentially avoiding late complications such as HIV encephalitis and dementia.

Unfortunately, early data seem to support the opposite hypothesis: the appearance of meningitis,[96] encephalopathy[97] or myelopathy[98] during seroconversion; intrathecal synthesis of HIV-1 antibody;[99] the recovery of HIV in the CSF[96] as well as a fulminating encephalitis in one patient accidentally injected with HIV, who died 15 days later.[100]

In keeping with the hypothesis of an early viral entry, Gray et al[101] described lymphocytic meningitis [Figure - 4]a, perivascular mononuclear infiltrates, discrete myelin pallor, astrocytic gliosis and microgliosis. Additional findings were discrete neuronal loss via apoptosis[102] and diffuse axonal damage.[103] After the detection of HIV-DNA in the brain tissue of asymptomatic individuals,[104] An et al revealed a condition of immune activation of the cerebral tissue [Figure - 4]b, with presence of toxic cytokines [Figure - 4]c.[105] Finally, the same group[71] found that, at this stage, astrocytes and endothelial cells, in addition to microglia [Figure - 4]d, are infected. However, viral replication remains very low during this stage.

The pathogenesis of HIV dementia

About 20 per cent of patients with AIDS develop a specific progressive cognitive/motor syndrome "HIV dementia" or AIDS-dementia complex (ADC), of which HIV-encephalitis was initially considered the pathological counterpart. Some groups still support this correlation,[106] whilst others were unable to confirm it,[90],[107],[108],[109] even applying morphometry[110] and PCR.[111],[112]

Other pathogenetic possibilities for the dementia were explored:

a) Microglial activation (MA),[110] although correlated by a number of observations,[71],[90],[113] remains a non specific finding.

b) Astrocytic abnormalities, including increased expression of adhesion molecules,[114] enhanced astrocyte activation[115] or loss of astrocytic function[72],[73],[116] could not be convincingly correlated.

c) The same was true for leukoencephalopathy[90],[110] and axonal damage, despite the consistent association of the latter with HIV encephalitis.[41]

d) Absence of correlation was also seen with poliodystrophy,[117],[118] as well as with cortical neuronal loss.[119]

As the various disorders associated with organic dementia have specific localisation for the cell loss, studies were carried out in the attempt at localising the cell loss also in HIV dementia. However, whereas Everall et al[120] found cell loss in the putamen, Bell et al[57] detected productive infection preferentially in the frontal cortex and Petito et al[121] reported reactive gliosis in the hippocampus.

The lack of exact correlation between the cognitive disorders and HIV-induced changes and recent reports of improvement of the cognitive disorders after HAART, suggest that HIVD might be the expression of a specific neuronal dysfunction resulting from the combined effects of several HIV-related neurotoxic factors, involving different aetiopathogenetic mechanisms some of which may be reversible.

If one accepts that HIVD reflects a specific neuronal dysfunction resulting from the combined action of HIV protein, glial and microglial activation, perhaps mediated by oxidative stress and glutamate-mediated excitotoxicity, its relationship with the different HIV-induced neuropathological changes is easier to understand.[122] Indeed, these changes may result from the same mechanisms: HIVE reflects productive HIV infection, HIVL is secondary to an alteration of the BBB resulting either from the effect of circulating factors or factors locally produced by activated macrophages. The same applies for axonal damage. Finally neuronal apoptosis and consequent DPD may result from the neurotoxicity of these combined factors or from axonal damage through retrograde degeneration. It is also possible that deafferentation of neurons may induce apoptosis in nerve cells. This hypothesis is in keeping with the description of synaptic and dendritic simplification in the brains of AIDS patients with severe HIVD[123] and in those with mild to moderate neurocognitive disorders.[124] The importance of the different factors may vary from one patient to another resulting in different histological features. This may explain why, although these lesions are more frequent in patients with HIVD, none can be strictly correlated to the cognitive impairment.

Modification of CNS complications of AIDS following the introduction of combination antiretroviral therapy (cART)

In 1981, reports of clusters of Pneumocystis pneumonia (PCP), Kaposi sarcoma and chronic mucocutaneous herpes simplex infection heralded the onset of the AIDS epidemic. Initially management of HIV disease was focused on treatment of opportunistic infections, such as PCP, cerebral toxoplasmosis and tumours, such as non-Hodgkin lymphoma. There was no specific HIV treatment available.

Later, in the late 1980s and early 1990s, with the introduction of prophylaxis against specific opportunistic infections (OIs) the incidence of AIDS-related OIs, such as PCP, began to fall.[125] Soon after, the introduction of nucleoside reverse-transcriptase inhibitor (NRTI) drugs coincided with a further reduction in both OIs and also HIV-associated dementia.[126]

In 1996 a new more powerful class of antiretroviral drugs, the protease inhibitors (PI) became available. Their introduction into clinical practice was associated with a dramatic reduction in incidence of AIDS-defining OIs and AIDS-associated deaths.[126],[127]

The term highly active antiretroviral therapy (HAART) was introduced to describe combinations of drugs used to treat HIV; HAART specifically refers to a combination of 2 NRTI class drugs, together with a PI class drug or a non-nucleoside reverse transcriptase inhibitor (NNRTI) class drug. Currently there are six classes of antiretroviral drugs available; NRTIs- such as zidovudine and lamivudine, nucleotide reverse transcriptase inhibitors (NtRTI) such as tenofovir, PIs such as ritonavir and amprenavir, NNRTIs such as efavirenz and nevirapine, fusion inhibitors such as enfuvirtide and integrase inhibitors such as raltegravir. The term combination antiretroviral therapy (cART) is now used to describe treatment of HIV infection using different classes of HIV drugs.

cART is successful in suppressing HIV replication;[128] improving cellular immunity[129] with protection against OIs.[130],[131],[132] Outside the nervous system, cART has decreased the incidence of tuberculosis[112],[133],[134] and of PCP;[135] prolonged survival in patients with tuberculosis and fungal infections[93] and prolongs survival in patients receiving chemotherapy for non-Hodgkin lymphoma.[136] In addition, several organ-specific disorders, including HIV-associated nephropathy, wasting syndrome and cardiomyopathy, all considered a direct consequence of HIV, benefit from cART. This review will deal only with the effects of cART on the nervous system.

In contrast to the reported success of prophylaxis and cART among HIV-infected patients in N America, Europe and Australasia, in parts of the world without access to these therapeutic interventions, because of financial constraints, such as southern Africa, HIV infection continues to spread relentlessly and patients continue to present with AIDS-defining OIs and malignancy, with attendant high rates of mortality.

While cART has unequivocally reduced rates of OIs and AIDS-related deaths in many cohort studies, it has many treatment-limiting side effects, notably those associated with NRTI-induced mitochondrial dysfunction, such as zidovudine-associated myopathy and stavudine-associated peripheral neuropathy and with PI-induced metabolic dysfunction, including dyslipidaemia and diabetes mellitus. Additionally many patients are intolerant of cART, as they experience nausea, anorexia, rash, biochemical hepatitis and neuropsychiatric side affects and in others development of genotypic and phenotypic resistance in HIV renders cART less or ineffective.

Unfortunately not all of the available antiretroviral drugs attain effective therapeutic levels in the CNS. Penetration of drugs across the blood-brain barrier (BBB) is dependant on several factors.[137] First, the integrity of the BBB; in advanced HIV there may be inflammation, facilitating diffusion of drugs. Second, cerebral blood flow may be influenced by HIV-associated nitric oxide production, permitting increased diffusion of drugs across the BBB. Third, endothelial cell-associated multidrug transporter proteins (MRP) act as unidirectional efflux pumps which may limit the ability of PIs to permeate brain tissue.[138] Fourth, the size, ionisation and lipophilicity of the drug molecule will influence the ease with which it will cross the BBB. Of currently available antiretroviral drugs, zidovudine penetrates the CNS most readily. The NNRI efavirenz also appears to penetrate the BBB and the boosted PI lopinavir/ritonavir (that is use of lopinavir together with a small dose of ritonavir) appears to suppress CSF HIV replication, despite the absence of measurable drug in CSF.[137],[139]

With regard to the CNS, despite a decrease in the number of AIDS-related post-mortems, brain disease remains a major cause of death. In the early stages, when HAART was administered to patients with severe immunodeficiency, the incidence of progressive multifocal leukoencephalopathy (PML) and primary non-Hodgkin lymphomas remained unchanged, whilst toxoplasmosis and CMV and HIV encephalitis decreased. On the other hand, when it was given at an early stage of immunosuppression, PML, CMV and primary lymphomas decreased, whereas infections occurring in mildly immunodeficient patients (VZV and HSV encephalitis) became more frequent. These data are reviewed and summarised by.[140]

But it soon became clear that these were not the only differences observed in this new era as other patients develop what has become known as 'burnt-out' lesions;[140] these result from treated forms of VZV encephalitis,[141] toxoplasmosis, HIVE and PML and are remarkable for the absence of both inflammation and infectious agents. These 'scar' lesions may be found in clinically and biologically cured patients who die from other causes as previously reported for toxoplasmosis.[142] In other instances, despite efficient treatment, the neurological condition of the patient may continue to deteriorate. In those patients with multifocal extensive toxoplasmosis or late treated HIVE or PML, it seems that, despite successful eradication of productive infection in the CNS, treatment was too late to prevent irreversible destructive lesions with, in some cases, secondary progressing  Wallerian degeneration More Details.[140]

In addition, in a minority of patients, HAART- and cATR-induced partial restoration of specific immunity may unmask or worsen a pre-existing disease. This complication, referred to as immune reconstruction inflammatory syndrome (IRIS) , is defined as a 'paradoxical deterioration in clinical status, attributable to the recovery of the immune system during HAART'.[143] Mycobacterial infection,[144],[145] CMV retinitis[146] and cryptococcal meningitis[147],[148] related to IRIS have been reported. In some patients with PML and receiving HAART, contrast enhancement revealed a florid inflammatory reaction, usually discrete in untreated individuals, which was confirmed by cerebral biopsy.[149],[150] In most cases, this correlated with prolonged survival and was interpreted as a marker of both improved immune status and outcome;[151],[152],[153] however in rare instances,[149] it coincided with clinical and radiological deterioration.

Fatal cases, possibly representing this syndrome, are those described by Langford et al[154] in 7 HAART-treated patients. In these, post-mortem revealed myelin loss, lympho-monocytic perivascular exudates, axonal injury and astrogliosis. All these changes were considered more severe than in the pre-HAART era. A pathologic and immunohistochemical account of the syndrome in the CNS was subsequently provided by Miller et al ;[155] they reported 2 patients who, despite HAART and a subsequent improved CD4 count and decreased HIV load in the CSF, developed fatal encephalopathy and diffuse myelin pallor [Figure - 5]a. In both, the brain tissue showed presence of HIV-DNA by PCR; the salient pathology consisted of diffuse microglial hyperplasia and massive perivascular [Figure - 5]b and intra-parenchymal [Figure - 5]c infiltration by CD8+/CD4- lymphocytes. It was suggested that the rapid immune reconstruction induced by the treatment led to a redistribution of lymphocytes into the peripheral blood. This was followed by recruitment of CD8+ cells into the brain, resulting in diffuse infiltration and consequent tissue damage. The latter could take place in two ways: either by ligating TNF receptor-like molecules by their corresponding ligands, triggering the apoptosis pathway or by secreting the content of cytoplasmic vesicles.[156] More recently Venkatarama et al[157] reported three patients with neurological manifestations of IRIS. In their patient 3 a brain biopsy confirmed the presence of HIV encephalitis and a severe infiltration by CD8 and fewer CD4 lymphocytes.

A fatal case in a patient with PML revealed, at neuropathological examination, two co-existing and equally undesirable, effects of this therapy: on the one hand an active inflammatory PML with abundant JCV together with massive intraparenchymal and perivascular infiltration by CD8+ lymphocytes in the absence of CD4+ lymphocytes [Figure - 5]d; this is a possible reaction to a smouldering active infection; on the other, an acute perivenous leukoencephalitis, similar to acute perivenous encephalomyelitis [Figure - 5]e, devoid of JCV[158] and considered a possible reaction to a latent antigen or inactive infectious agent.[159] It is suggested that both patterns may relate to CD8+lymphocyte cytotoxicity.[160]

Finally, as HAART and cART have effectively lengthened the life expectancy of HIV-infected individuals, additional chronic patterns of HIV encephalitis have arisen that may explain the shift of the clinical manifestations from severe dementia to more subtle minor cognitive impairment.[161] A recent post mortem study in AIDS patients well treated by HAART, revealed high level of microglia/macrophage activation, particularly in the hippocampus where the degree of inflammation was higher than in control cases, pre-HAART AIDS and presymptomatic brains. This is consistent with reports of clinical examination and neuroimaging in HAART-treated individuals, suggesting that alterations in the hippocampus are more pronounced than was observed pre-HAART.[162] Although no evidence of dementia was observed the patients, the persistence of an ongoing neuroinflammation and the shift in its distribution to the hippocampus may pose a threat for the future health of individuals maintained long-term on HAART.[163]

Also, there is a concern that additional factors including aging and the secondary effects of treatment may worsen the course of the cognitive disorders. Increased cerebrovascular risk may result from metabolic changes (dyslipidemia, insulin resistance and changes in body fat) associated with chronic antiretroviral therapy.[164] Finally brain deposition of beta-amyloid has been shown to be a common pathologic feature in HIV positive patients[165] consistent with experimental demonstration that HIV protein tat inhibits beta-amyloid degradation by neprelysin[166] and with clinical observation of significantly decreased CSF beta-amyloid and increased tau concentrations similar to Alzheimer disease in HIV dementia.[167]

   Conclusion Top

It now appears that introduction of HAART has dramatically modified the course and prognosis of HIV infection. However these encouraging results are restricted to the developed world where treatment is widely available; in addition, their impact on the HIV-associated cognitive disorders, which represent the most disabling complications of the disease, is not clearly established; finally new HAART -related neurological complications have appeared. Therefore it is crucial that further research continue both for a better understanding of the mechanisms of neurodegeneration and for wider prevention and treatment of HIV infection.

   References Top

1.Nathan DG. Clinical research: Perceptions, reality and proposed solutions. National Institute of Health Director's Panel on Clinical Research. JAMA 1998;280:1427-31.  Back to cited text no. 1    
2.Phoolcharoen W. HIV/AIDS prevention in Thailand: Success and challenges. Science 1998;280:1873-4.  Back to cited text no. 2    
3.Shacker T, Collier AC, Hughes J, Shea T, Corey L. Clinical and epidemiologic features of primary HIV infection. Ann Int Med 1996;125:257-64.  Back to cited text no. 3    
4.Opportunistic infections and Kaposi's sarcoma among Haitians in the United States. Conn Med 1982;46:727-8.  Back to cited text no. 4    
5.Barrι-Sinoussi F, Cherman JC, Rey F, Nugeyre MT, Chamaret S, Gruest J, et al . Isolation of T-lymphotropic retrovirus from a patient at risk for acquired immune deficiency syndrome. Science 1983;220:868-71.  Back to cited text no. 5    
6.Popovic M, Sarngadharan MG, Read E, Gallo RC. Detection, isolation and continuous production of cytopathic retrovirus (HTLV-III) from patients with AIDS and pre-AIDS. Science 1984;224:497-500.  Back to cited text no. 6    
7.Snider WD, Simpson DM, Nielsen S, Gold JW, Metroka CE, Posner JB. Neurological complications of acquired immune deficiency syndrome: Analysis of 50 patients. Ann Neurol 1983;14:403-18.  Back to cited text no. 7    
8.Gray F, Geny C, Lionnet F, Dournon E, Fenelon G, Gherardi R, et al . Neuropathologic study of 135 adult cases of acquired immunodeficiency syndrome (AIDS) Ann Pathol 1991;11:236-47.   Back to cited text no. 8    
9.Sharer LR. Pathology of HIV-1 infection of the central nervous system. A review. J Neuropathol Exp Neurol 1992;51:3-11.  Back to cited text no. 9    
10.Gallo RC, Salahuddin SZ, Popovic M, Shearer GM, Kaplan M, Haynes BF, et al . Frequent detection and isolation of cytopathic retroviruses (HTLV-III) from patients with AIDS and at risk for AIDS. Science 1984;224:500-3.  Back to cited text no. 10    
11.Weiss R. Human T-cell retroviruses. In : Weiss R, et al , editors. RNA tumor viruses, 2nd ed, vol 2. Supplements and appendices. Cold Spring Harbor Laboratory: New York; 1985. p. 405-85.  Back to cited text no. 11    
12.Daniel MD, Letvin NL, King NW, Kannagi M, Sehgal PK, Hunt RD, et al . Isolation of t-cell tropic HTLV-III-like retrovirus from macaques. Science 1985;228:1201-4.  Back to cited text no. 12    
13.Gao F, Bailes E, Robertson DL, Chen Y, Rodenburg CM, Michael SF, et al . Origin of HIV-1 in the chimpanzee Pan troglodytes troglodytes. Nature 1999;397:436-41.  Back to cited text no. 13    
14.Nahmias AJ, Weiss J, Yao X, Lee F, Kodsi R, Schanfield M, et al . Evidence for human infection with an HTLVIII/LAV-like virus in Central Africa, 1959. Lancet 1986;1:1279-80.  Back to cited text no. 14    
15.Witte MH, Witte CL, Minnich LL, Finley PR, Drake WL Jr. AIDS in 1968. JAMA 1984;251:2657.  Back to cited text no. 15    
16.Dalgliesh AG, Beverley PC, Clapman PR, Crawford DH, Greaves MF, Weiss RA. The CD4 (T4) antigen is an essential component of the receptor for the AIDS retrovirus. Nature 1985;312:767-7.  Back to cited text no. 16    
17.Klatzmann D, Champagne E, Chamaret S, Gruest J, Guetard D, Hercend D, et al . T-lymphocyte T4 molecule behaves as the receptor for human retrovirus LAV. Nature 1984;312:767-8.  Back to cited text no. 17    
18.Meltzer MS, Gendelman HE. Mononuclear phagocytes as targets, tissue reservoirs and immunoregulatory cells in human immunodeficiency virus disease. Curr Top Microbiol Immunol 1992;181:239-63.  Back to cited text no. 18    
19.Vazeux R, Brousse N, Jarry A, Henin D, Marche C, Vedrenne C, et al . AIDS subacute encephalitis. Identification of HIV-infected cells. Am J Pathol 1987;126:403-10.  Back to cited text no. 19    
20.Feng Y, Broder CC, Kennedy PE, Berger EA. HIV-1 entry cofactor: Functional cDNA cloning of a seven transmembrane, G protein-coupled receptor. Science 1996;272:872-7.  Back to cited text no. 20    
21.Dragic T, Litwin V, Allaway GP, Martin SR, Huang Y, Nagashima KA, et al . HIV-1 entry into CD4+ cells is mediated by the chemokine receptor CC-CKR-5. Nature 1996;381:667-73.  Back to cited text no. 21    
22.Evans LA, Levy JA. Characteristics of HIV infection and pathogenesis. Biochem Biophys Acta 1989;989:237-54.  Back to cited text no. 22    
23.Harcourt-Webster JN. General pathology. In : Scaravilli F, editor. The neuropathology of HIV infection. Springer: London; 1993. p. 53-98.  Back to cited text no. 23    
24.Lang W, Miklossy J, Deruaz JP, Pizzolato GP, Probst A, Schaffner T, et al . Neuropathology of the acquired immune deficiency syndrome (AIDS): A report of 135 consecutive autopsy cases from Switzerland. Acta Neuropathol 1989;77:379-90.  Back to cited text no. 24    
25.Morgello S, Cho ES, Nielsen S, Devinsky O, Petito CK. Cytomegalovirus encephalitis in patients with acquired immunodeficiency syndrome: An autopsy study of 30 cases and a review of the literature. Hum Pathol 1987;18:289-97.  Back to cited text no. 25    
26.Petito CK, Cho ES, Lemann W, Navia BA, Price RW. Neuropathology of acquired immunodeficiency syndrome (AIDS):an autopsy review. J Neuropathol Exp Neurol 1986;45:635-46.  Back to cited text no. 26    
27.Budka H, Costanzi G, Cristina S, Lechi A, Parravicini C, Trabattoni R, et al . Brain pathology induced by infection with the human immunodeficiency virus (HIV). A histological, immunocytochemical, and electron microscopical study of 100 autopsy cases. Acta Neuropathol (Berl) 1987;75:186-98.  Back to cited text no. 27    
28.Vinters HV, Tomiyasu U, Anders KH. Neuropathologic complications of infection with the human immunodeficiency virus (HIV). Prog AIDS Pathol 1989;1:101-30.  Back to cited text no. 28    
29.Kovacs JA, Kovacs AA, Polis M, Wright WC, Gill VJ, Tuazon CU, et al . Cryptococcosis in the acquired immunodeficiency syndrome. Ann Intern Med 1985;103:533-8.  Back to cited text no. 29    
30.Gray F, Gherardi R, Keohane C, Favolini M, Sobel A, Poirier J. Pathology of the central nervous system in 40 cases of acquired immune deficiency syndrome (AIDS). Neuropathol Appl Neurobiol 1988;14:365-80l.  Back to cited text no. 30    
31.Hιnin D, Duyckaerts C, Chaunu MP, Vazeux R, Brousse N, Rozenbaum W, et al . Neuropathological study of 31 cases of acquired immunodeficiency syndrome. Rev Neurol (Paris) 1987;143:631-42.  Back to cited text no. 31    
32.Levy RM, Bredesen DE, Rosenblum ML. Opportunistic central nervous system pathology in patients with AIDS. Ann Neurol 1988;23:S7-12.   Back to cited text no. 32    
33.Luft BJ, Brooks RG, Conley FK, McCabe RE, Remington JS. Toxoplasmic encephalitis in patients with acquired immune deficiency syndrome. JAMA 1984;252:913-7.  Back to cited text no. 33    
34.Hanto DW, Frizzera G, Purtilo DT, Sakamoto K, Sullivan JL, Saemundsen AK, et al . Clinical spectrum of lymphoproliferative disorders in renal transplant recipients and evidence for the role of Epstein-Barr virus. Cancer Res 1981;41:4253-61.  Back to cited text no. 34    
35.Fauci AS, Macher AM, Longo DL, Lane HC, Rook AH, Masur H, et al . Acquired immunodeficiency syndrome: Epidemiologic, clinical, immunologic and therapeutic considerations. Ann Int Med 1984;100:92-106.  Back to cited text no. 35    
36.Geddes JF, Battacharjee MB, Savage K, Scaravilli F, McLaughlin JE. Primary cerebral lymphoma: A study of 47 cases probed for Epstein-Barr virus genome. J Clin Pathol 1992;45:587-90.  Back to cited text no. 36    
37.Shaw GM, Harper ME, Hahn BH, Epstein LG, Gajdusek DC, Price RW, et al . HTLV-III infection in brains of children and adults with AIDS encephalopathy. Science 1985;227:177-82.  Back to cited text no. 37    
38.Sharer LR, Cho ES, Epstein LG. Multinucleated giant cells and HTLV-III in AIDS encephalopathy. Hum Pathol 1985;16:760.  Back to cited text no. 38    
39.Budka H. Multinucleated giant cells in brain: A hallmark of the acquired immune deficiency syndrome (AIDS). Acta Neuropathol 1986;69:253-8.  Back to cited text no. 39    
40.Budka H, Wiley CA, Kleihues P, Artigas J, Asbury AK, Cho ES, et al . HIV associated disease of the nervous system: Review and nomenclature and proposal for neuropathology-based terminology. Brain Pathol 1991;1:143-52.  Back to cited text no. 40    
41.Giometto B, An SF, Groves M, Scaravilli T, Geddes JF, Miller R, et al . Accumulation of beta-amyloid precursor protein in HIV encephalitis: Relationship with neurophysiological abnormalities. Ann Neurol 1997;42:34-40.  Back to cited text no. 41    
42.Schmidbauer M, Huemer M, Cristina S. Morphological spectrum, distribution and clinical correlations of white matter lesions in AIDS brains. Neuropathol Appl Neurobiol 1982;18:489-501.  Back to cited text no. 42    
43.Smith TW, De Girolami U, Hιnin D, Bolgert F, Hauw JJ. Human immunodeficiency virus (HIV) leukoencephalopathy and the microcirculation. J Neuropathol Exp Neurol 1990;49:357-70.  Back to cited text no. 43    
44.Power C, Kong PA, Crawford TO, Wesselingh S, Glass JD, McArthur JC, et al . Cerebral white matter changes in acquired immunodeficiency syndrome dementia: Alterations of the blood-brain-barrier. Ann Neurol 1993;34:339-50.  Back to cited text no. 44    
45.Boven LA, Middle J, Verhoef J, De Groot CJ, Nottet HS. Monocyte infiltration is highly associated with loss of the tight junction protein zonula occludens in HIV-a-associated dementia. Neuropathol Appl Neurobiol 2000;26:356-60.  Back to cited text no. 45    
46.Petito CK, Cask KS. Blood brain barrier abnormality in the acquired immunodeficiency syndrome: Immunohistochemical localization of serum proteins in post-mortem brain. Ann Neurol 1992;32:658-66.  Back to cited text no. 46    
47.Ciardi A, Sinclair E, Scaravilli F, Harcourt-Webster NJ, Lucas S. The involvement of the cerebral cortex in human immunodeficiency virus encephalopathy: A morphological and immunohistochemical study. Acta Neuropathol (Berl) 1990;81:51-9.  Back to cited text no. 47    
48.Everall IP, Luthert P, Lantos PL. A review of neuronal damage in human immunodeficiency virus infection: Its assessment, possible mechanism and relationship to dementia. J Neuropathol Exp Neurol 1993;52:561-6.  Back to cited text no. 48    
49.Adle-Biassette H, Levy Y, Colombel M, Poron F, Natchev S, Keohane C, et al . Neuronal apoptosis in HIV infection in adults. Neuopathol Appl Neurobiol 1995;21:218-27.  Back to cited text no. 49    
50.Petito CK, Roberts B. Evidence of apoptotic cell death in HIV encephalitis. Am J Pathol 1995;146:1121-30.  Back to cited text no. 50    
51.Shi B, De Girolami U, He J, Wang S, Lorenzo A, Busciglio J, et al . Apoptosis induced by HIV-1 infection of the central nervous system. J Clin Invest 1996;98:1979-90.  Back to cited text no. 51    
52.Epstein LG, Sharer LR, Goudsmit J. Neurological and neuropathological features of human immunodeficiency virus infection in children. Ann Neurol 1988;23:S19-23.  Back to cited text no. 52    
53.Sharer LR, Cho ES. Neuropathology of HIV infection:adults vs children. Progr AIDS Pathol 1989;1:131-41.  Back to cited text no. 53    
54.Sharer LR, Epstein LG, Cho ES, Joshi VV, Meyenhofer MF, Rankin LF, et al . Pathologic features of AIDS encephalopathy in children: Evidence for LAV/HTLV-III infection of brain. Hum Pathol 1986;17:271-84.  Back to cited text no. 54    
55.Gelbard HA, James HJ, Sharer LR, Perry SW, Saito Y, Kazee AM, et al . Apoptotic neurons in brains from paediatric patients with HIV-1 encephalitis and progressive encephalopathy. Neuropathol Appl Neurobiol 1995;21:208-17.  Back to cited text no. 55    
56.Esiri MM, Scaravilli F, Millard PR, Harcourt-Webster JN. Neuropathology of HIV infection in haemophiliacs: Comparative necropsy study. BMJ 1989;299:1312-5.  Back to cited text no. 56    
57.Bell JE, Brettle RP, Chiswick A, Simmonds P. HIV encephalitis, proviral load and dementia in drug users and homosexuals with AIDS. Effect of neocortical involvement. Brain 1998;121:2043-52.  Back to cited text no. 57    
58.Goldstick L, Mandybur TI, Bode R. Spinal cord degeneration in AIDS. Neurology 1985;35:103-6.  Back to cited text no. 58    
59.Artigas J, Grosse G, Niedobitek F. Vacuolar myelopathy in AIDS. A morphological analysis. Pathol Res Pract 1990;186:228-37.  Back to cited text no. 59    
60.Sharer LR, Dowling PC, Michaels J, Cook SD, Menonna J, Blumberg BM, et al . Spinal cord disease in children with HIV-1 infection: A combined molecular biological and neuropathological study. Neuropathol Appl Neurobiol 1990;16:317-31.  Back to cited text no. 60    
61.Petito CK, Navia BA, Cho ES, Jordan BD, George DC, Price RW. Vacuolar myelopathy pathologically resembling subacute combined degeneration in patients with acquired immunodeficiency syndrome. N Engl J Med 1985;312:874-9.  Back to cited text no. 61    
62.Tan SV, Guiloff RJ, Scaravilli F. AIDS-associated vacuolar myelopathy. A morphometric study. Brain 1995;118:1247-61.  Back to cited text no. 62    
63.Budka H, Maier H, Pokl P. Human immunodeficiency virus in vacuolar myelopathy of the acquired immunodeficiency syndrome. N Engl J Med 1988;319:1667-8.  Back to cited text no. 63    
64.Maier H, Budka H, Lassmann H, Pohl P. Vacuolar myelopathy with multinucleated giant cells in the acquired immunodeficiency syndrome (AIDS). Light and electron microscopic distribution of the human immunodeficiency virus (HIV) antigens. Acta Neuropathol 1989;78:497-503.  Back to cited text no. 64    
65.Kamin SS, Petito CK. Idiopathic myelopathies with white matter vacuolation in non-acquired immunodeficiency patients. Hum Pathol 1991;22:816-24.   Back to cited text no. 65    
66.Tyor WR, Glass JD, Baumrind N, McArthur JC, Griffin JW, Becker PS, et al . Cytokine expression of macrophages in HIV-1-associated vacuolar myelopathy. Neurology 1993;43:1002-9.  Back to cited text no. 66    
67.Kimura-Kuroda J, Nagashima K, Yasui K. Inhibition of myelin formation by HIV-1 gp-120 in rat cerebral cortex culture. Arch Virol 1994;137:81-99.  Back to cited text no. 67    
68.Mizusawa H, Hirano A, Llena JF, Shintaku M. Cerebrovascular lesions in acquired immunodeficiency syndrome (AIDS). Acta Neuropathol 1988;76:451-7.  Back to cited text no. 68    
69.Yankner BA, Skolnik PR, Shoukimas GM, Gabuzda DH, Sobel RA, Ho DD. Cerebral granulomatous angiitis associated with isolation of human lymphotropic virus type III from the central nervous system. Ann Neurol 1986;20:362-4.  Back to cited text no. 69    
70.Scaravilli F, Daniel SE, Harcourt-Webster N, Guiloff RJ. Chronic basal meningitis and vasculitis in acquired immunodeficiency syndrome. A possible role for human immunodeficiency virus. Arch Pathol Lab Med 1989;113:192-5.  Back to cited text no. 70    
71.An SF, Groves M, Giometto B, Beckett AA, Scaravilli F. Detection and localisation of HIV-1 DNA and RNA in fixed adult AIDS brain by polymerase chain reaction/in situ hybridisation technique. Acta Neuropathol 1999;98:481-7.  Back to cited text no. 71    
72.Saito Y, Sharer LR, Epstein LG, Michaels J, Mintz M, Louder M, et al . Over expression of nef as a marker for restricted HIV-1 infection of astrocytes in post-mortem pediatric central nervous tissue. Neurology 1994;44:474-81.  Back to cited text no. 72    
73.Tornatore C, Chandra R, Berger JR, Major EO. HIV-1 infection of subcortical astrocytes in the pediatric central nervous system. Neurology 1994;44:481-7.  Back to cited text no. 73    
74.Wiley CA, Schrier RD, Nelson JA, Lampert PW, Oldstone MB. Cellular localisation of human immunodeficiency virus infection within the brains of acquired immunodeficiency syndrome patients. Proc Natl Acad Sci USA 1986;83:7089-93.  Back to cited text no. 74    
75.Nuovo GJ, Gallery F, MacConnell P, Braun A. In situ detection of polymerase chain reaction-amplified HIV-1 nucleic acids and tumor necrosis factor-alpha RNA in the central nervous system. Am J Pathol 1994;144:659-66.  Back to cited text no. 75    
76.Bagasra O, Lavi E, Bobroski L, Khalili K, Pestaner JP, Tawadros R, et al . Cell reservoirs of HIV-1 in the central nervous system of infected individuals: Identification by the combination of in situ polymerase chain reaction and immunohistochemistry. AIDS 1996;10:573-5.   Back to cited text no. 76    
77.Sharer LR, Saito Y, Epstein LG, Blumberg BM. Detection of HIV-1 DNA in pediatric AIDS brain tissue by two step ISPCR. Adv Neuroimmunol 1994;4:283-5.  Back to cited text no. 77    
78.Bissel SJ, Wiley CA. Human immunodeficiency virus infection of the brain: Pitfalls in evaluating infected/affected cell populations. Brain Pathol 2004;14:97-108.  Back to cited text no. 78    
79.Nath A, Conant K, Chen P, Scott C, Major EO. Transient exposure to HIV-1 Tat protein results in cytokine production in macrophages and astrocytes. A hit and run phenomenon. J Biol Chem 1999;274:17098-101.  Back to cited text no. 79    
80.Kaul M, Garden GA, Lipton SA. Pathways to neuronal injury and apoptosis in HIV-associated dementia. Nature 2001;410:988-94.  Back to cited text no. 80    
81.Bruce-Keller AJ, Chauhan A, Dimayuga FO, Gee J, Keller JN, Nath A. Synaptic transport of human immunodeficiency virus-Tat protein causes neurotoxicityand gliosis in rat brain. J Neurosci 2003;23:8417-22.  Back to cited text no. 81    
82.Dewhurst S, Gelbard HA, Fine SM. Neuropathogenesis of AIDS. Mol Med Today 1996;2:16-23.  Back to cited text no. 82    
83.Haughey NJ, Nath A, Mattson MP, Slevin JT, Geiger JD. HIV-1 Tat through phosphorylation of NMDA receptors potentiates glutamate excitotoxicity. J Neurochem 2001;78:457-67.  Back to cited text no. 83    
84.Lipton SA. HIV-related neurotoxicity. Brain Pathol 1991;1:193-9.  Back to cited text no. 84    
85.Ferrarese C, Aliprandi A, Tremolizzo L, Stanzani L, De Micheli A, Dolara A, et al . Increased glutamate in CSF and plasma of patients with HIV dementia. Neurology 2001;57:671-5.  Back to cited text no. 85    
86.Heyes MP, Ellis RJ, Ryan L, Childers ME, Grant I, Wolfson T, et al . Elevated cerebro spinal fluid quinolinic acid levels are associated with region-specific cerebral volume loss in HIV infection. Brain 2001;124:1033-42.  Back to cited text no. 86    
87.Gras G, Chrιtien F, Vallat-Decouvelaere AV, Le Pavec G, Porcheray F, Bossuet C, et al . Regulated expression of sodium-dependent glutamate transporters and synthetase: A neuroprotective role for activated microglia and macrophages in HIV infection? Brain Pathol 2003;13:211-22.  Back to cited text no. 87    
88.Vallat-Decouvelaere AV, Chrιtien F, Gras G, Le Pavec G, Dormont D, Gray F. Expression of excitatory amino acid-transporter-1 in brain macrophages and microglia of HIV patients. A neuroprotective role for microglia? J Neuropathol Exp Neurol 2003;62:475-85.  Back to cited text no. 88    
89.Xu Y, Kulkosky J, Acheampong E, Nunnari G, Sullivan J, Pomerantz RJ. HIV-1-mediated apoptosis of neuronal cells: Proximal molecular mechanisms of HIV-1-induced encephalopathy. Proc Natl Acad Sci USA 2004;101:7070-5.  Back to cited text no. 89    
90.Adle-Biassette H, Chrιtien F, Wingertsmann L, Hery C, Ereau T, Scaravilli F, et al . Neuronal apoptosis does not correlate with dementia in HIV infection but is related to microglial activation and axonal damage. Neuropathol Appl Neurobiol 1999;25:123-33.  Back to cited text no. 90    
91.Adamson DC, Wildemann B, Sasaki M, Glass JD, McArthur JC, Christov VI, et al . Immunologic NO synthase: Elevation in severe AIDS dementia and induction by HIV-1 gp41. Science 1996;274:1917-21.  Back to cited text no. 91    
92.Shi B, Raina J, Lorenzo A, Busciglio J, Gab uzda D. Neuronal apoptosis induced by HIV-1 Tat protein and TNF-alpha: Potentiation of neurotoxicity mediated by oxidative stress and implication for HIV-1 dementia. J Neurovirol 1998;4:281-90.  Back to cited text no. 92    
93.Begovac J, Lisic M, Lukas D, Maretic T, Kniewald T, Novotny TE. Marked improvement in survival among adult Croatian AIDS patients after the introduction of highly active antiretroviral treatment. Coll Antropol 2006;30:175-9.  Back to cited text no. 93    
94.Nath A, Geiger J. Neurobiological aspects of human immunodeficiency virus infection: Neurotoxic mechanisms. Progr Neurobiol 1998;54:19-33.  Back to cited text no. 94    
95.Li W, Galey D, Mattson MP, Nath A. Molecular and cellular mechanisms of neuronal cell death in HIV dementia. Neurotox Res 2005;8:119-34.  Back to cited text no. 95    
96.Ho DD, Rota TR, Schooley RT, Kaplan JC, Allan JD, Groopman JE, et al . Isolation of HTLV-III from cerebrospinal fluid and neural tissues of patients with neurological syndromes related to the acquired immunodeficiency syndrome. N Engl J Med 1985;313:1493-7.  Back to cited text no. 96    
97.Carne CA, Tedder RS, Smith A, Sutherland S, Elkington SG, Daly HM, et al . Acute encephalopathy coincident with seroconversion for anti-HTLV-III. Lancet 1985;2:1206-8.  Back to cited text no. 97    
98.Denning DW, Anderson J, Rudge P, Smith H. Acute myelopathy associated with primary infection with human immunodeficiency virus. Br Med J 1987;294:143-4.  Back to cited text no. 98    
99.Resnick L, Burger JR, Shapshak P, Tourtellotte WW. Early penetration of the blood-brain-barrier by HIV. Neurology 1988;38:9-14.  Back to cited text no. 99    
100.Davis LE, Hjelle BL, Miller VE, Palmer DL, Llewellyn AL, Merlin TL, et al . Early viral brain invasion in iatrogenic human immunodeficiency virus infection. Neurology 1992;42:1736-9.  Back to cited text no. 100    
101.Gray F, Lescs MC, Keohane C, Paraire F, Marc B, Durigon M, et al . Early brain changes in HIV infection: Neuropathological study of 11 HIV-seropositive, no-AIDS cases. J Neuropathol Exp Neurol 1992;51:177-85.  Back to cited text no. 101    
102.An SF, Giometto B, Scaravilli T, Tavolato B, Gray F, Scaravilli F. Programmed cell death in brains of HIV-1-positive AIDS and pre-AIDS patients. Acta Neuropathol 1996a;91:169-73.  Back to cited text no. 102    
103.An SF, Giometto B, Groves M, Miller RF, Beckett AA, Gray F, et al . Axonal damage revealed by accumulation of β-APP in HIV-positive individuals without AIDS. J Neuropathol Exp Neurol 1997;56:1262-8.  Back to cited text no. 103    
104.An SF, Giometto B, Scaravilli F. HIV-1 DNA in brains in AIDS and pre-AIDS: Correlation with the stage of the disease. Ann Neurol 1996b;40:611-7.  Back to cited text no. 104    
105.An SF, Ciardi A, Giometto B, Scaravilli T, Gray F, Scaravilli F. 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. Acta Neuropathol 1996;91:494-503.  Back to cited text no. 105    
106.Wiley CA, Achim C. Human immunodeficiency virus encephalitis is the pathological correlate of dementia in acquired immunodeficiency syndrome. Ann Neurol 1994;36:673-6.  Back to cited text no. 106    
107.Brew BJ, Rosenblum M, Cronin K, Price RW. AIDS dementia complex and HIV-1 brain infection: Clinical-virological correlations. Ann Neurol 1995;38:563-70.  Back to cited text no. 107    
108.Gray F, Haug H, Chimelli L, Geny C, Gaston A, Scaravilli F, et al . Prominent cortical atrophy with neuronal loss as correlate of human immunodeficiency virus encephalopathy. Acta Neuropathol 1991;82:229-33.  Back to cited text no. 108    
109.Navia BA, Cho ES, Petito CK, Price RW. The AIDS dementia complex: II. Neuropathology. Ann Neurol 1986a;19:525-35.  Back to cited text no. 109    
110.Glass JD, Wesselingh SL, Selnes OA, McArthur JC. Clinical-neuropathologic correlation in HIV-associated dementia. Neurology 1993;43:2230-7.  Back to cited text no. 110    
111.Johnson RT, Glass JD, McArthur JC, Chesebro BW. Quantitation of human immunodeficiency virus in brains of demented and non demented patients with acquired immunodeficiency syndrome. Ann Neurol 1996;39:392-5.  Back to cited text no. 111    
112.Lazarini F, Seilhean D, Rosenblum O, Suarez S, Conquy L, Uchihara T, et al . Human immunodeficiency virus type 1 DNA and RNA load in brains of demented and nondemented patients with acquired immunodeficiency syndrome. J Neurovirol 1997;3:299-303.  Back to cited text no. 112    
113.Sinclair E, Gray F, Ciardi A, Scaravilli F. Immunohistochemical changes and PCR detection of HIV provirus DNA in brains of asymptomatic HIV-positive patients. J Neuropathol Exp Neurol 1994;53:43-50.  Back to cited text no. 113    
114.Seilhean D, Dzia-Lepfoundzou A, Sazdovitch V, Cannella B, Raine CS, Katlama C, et al . Astrocytic adhesion molecules are increased in HIV-associated cognitive/motor complex. Neuropathol Appl Neurobiol 1997;23:83-92.  Back to cited text no. 114    
115.Geiger KD, Stoldt P, Schlote W, Derouiche A. Ezrin immunoreactivity reveals specific astrocyte activation in cerebral HIV. J Neuropathol Exp Neurol 2006;65:87-96.  Back to cited text no. 115    
116.Vallat AV, De Girolami U, He J, Mhashilkar A, Marasco W, Shi B, et al . Localization of HIV-1 co-receptors CCR5 and CXCR4 in the brain of children with AIDS. Am J Pathol 1998;152:167-78.  Back to cited text no. 116    
117.Everall IP, Glass JD, McArthur J, Spargo E, Lantos P. Neuronal density in the superior frontal and temporal gyri does not correlate with the degree of human immunodeficiency virus-associated dementia. Acta Neuropathol 1994;88:538-44.  Back to cited text no. 117    
118.Weis S, Haug H, Budka H. Astroglial changes in the cerebral cortex of AIDS brains: A morphometric and immunohistochemical investigation. Neuropathol Appl Neurobiol 1993;19:329-35.  Back to cited text no. 118    
119.Seilhean D, Duyckaerts C, Vazeux R, Bolgert F, Brunet P, Katlama C, et al . HIV-associated cognitive/motor complex: Absence of neuronal loss in the cerebral neocortex. Neurology 1993;43:1492-9.  Back to cited text no. 119    
120.Everall I, Barnes H, Spargo E, Lantos P. Assessment of neuronal density in the putamen in human immunodeficiency virus (HIV) infection. Application of stereology and spatial analysis of quadrats. J Neurovirol 1995;1:126-9.  Back to cited text no. 120    
121.Petito CK, Roberts B, Cantando JD, Rabinstein A, Duncan R. Hippocampal injury and alterations in neuronal chemochine co-receptor expression in patients with AIDS. J Neuropathol Exp Neurol 2001;60:377-85.  Back to cited text no. 121    
122.Gray F, Adle-Biassette H, Chrιtien F, et al . Neuropathology and neurodegeneration in human immunodeficiency virus infection. Pathogenesis of HIV-induced lesions of the brain, correlations with HIV-associated disorders and modifications according to treatments. Clin Neuropathol 2001;20:146-55.  Back to cited text no. 122    
123.Masliah E, Heaton RK, Marcotte TD, Ellis RJ, Wiley CA, Mallory M, et al . Dendritic injury is a pathological substrate for human immunodeficiency virus-related cognitive disorders. HNRC Group. The HIV Neurobehavioral Research Center. Ann Neurol 1997;42:963-72.  Back to cited text no. 123    
124.Everall IP, Heaton RK, Marcotte TD, Ellis RJ, McCutchan JA, Atkinson JH, et al . Cortical synaptic density is reduced in mild to moderate human immunodeficiency virus neurocognitive disorder. HNRC Group. HIV Neurobehavioral Research Center. Brain Pathol 1999;9:209-17.  Back to cited text no. 124    
125.McNaghten AD, Hanson DL, Jones JL. Effects of antiretroviral therapy and opportunistic illness primary chemoprophylaxis on survival after AIDS diagnosis. AIDS 1999;13:1687-95.  Back to cited text no. 125    
126.Kaplan JE, Hanson D, Dworkin MS, Frederick T, Bertolli J, Lindegren ML, et al . Epidemiology of human immunodeficiency virus-associated opportunistic infections in the United States in the era of highly active antiretroviral therapy. Clin Infect Dis 2000;30:S5-14.  Back to cited text no. 126    
127.Brodt HR, Kamps BS, Gute P, Knupp B, Staszewski S, Helm EB. Changing incidence of AIDS-defining illnesses in the era of antiretroviral combination therapy. AIDS 1997;11:1731-8.  Back to cited text no. 127    
128.Pakker NG, Ross MTL, van Leeuwen R, de Jong MD, Koot M, Reiss P, et al . Patterns of T cell repopulation, virus load reduction and restoration of T cell function in HIV-infected persons during therapy with different antiretrovirals. J Acquir Immune Defic Syndr Hum Retrovirol 1997;16:318-26.  Back to cited text no. 128    
129.Autran B, Carcelain G, Li TS, Blanc C, Mathez D, Tubiana R, et al . Positive effects of combined antiretroviral therapy on CD4+ T cells homeostasis and function in advanced HIV cases. Science 1997;277:112-6.  Back to cited text no. 129    
130.Jellinger KA, Setinek U, Drilicek M, Bohm G, Steurer A, Lintner F. Neuropathology and general autopsy findings in AIDS during the last 15 years. Acta Neuropathol 2000;100:213-20.  Back to cited text no. 130    
131.Maschke M, Kastrup O, Esser S, Ross B, Hengge U, Hufnagel A. Incidence and prevalence of neurological disorders associated with HIV since the introduction of highly active antiretroviral therapy (HAART). J Neurol Neurosurg Psychiat 2000;69:376-80.  Back to cited text no. 131    
132.Sacktor NC, Lyles RH, Skolasky R. The multicenter AIDS Cohort Study. HIV-1-related neurological disease incidence changes in the era of highly active antiretroviral therapy. Neurology 1999;52:A252-3.  Back to cited text no. 132    
133.Jerene D, Naess A, Lindtjorn B. Antiretroviral therapy at a district hospital in Ethiopia prevents death and tuberculosis in a cohort of HIV patients. AIDS Res Ther 2006;3:10.  Back to cited text no. 133    
134.Lawn SD, Badri M, Wood R. Tuberculosis among HIV-infected patients receiving HAART: Long term incidence and risk factors in South African cohort. AIDS 2005;19:2109-16.  Back to cited text no. 134    
135.Torre D, Speranza F, Martregani R. Impact of highly active antiretroviral therapy on organ-specific manifestations of HIV-1 infection. HIV Med 2005;6:66-78.  Back to cited text no. 135    
136.Hoffmann C, Tabrizian S, Wolf E, Eggers C, Stoehr A, Plettenberg A, et al . Survival of AIDS patients with primary central nervous system lymphoma is dramatically improved by HAART-induced immune recovery. AIDS 2001;15:2119-27.  Back to cited text no. 136    
137.Boffito M, Pillay D, Wilkins E. Management of advanced HIV disease: Resistance, antiretroviral brain penetration and malignancies. Int J Clin Pract 2006;60:1098-106.  Back to cited text no. 137    
138.Srinivas RV, Midlemas D, Flynn P, Fridland A. Human immunodeficiency virus protease inhibitors serve as substrates for multidrug transporter proteins MDR1 and MRP1 but retain antiviral efficiency in cell lines expressing these transporters. Antimicrob Agents Chemother 1998;42:3157-62.  Back to cited text no. 138    
139.Lafeuillade A, Solas C, Halfon P, Chadapaud S, Hittinger G, Lacarelle B. Differences in the detection of three HIV-1 protease inhibitors in non-blood compartments: Clinical correlations. HIV Clin Trials 2002;3:27-35.  Back to cited text no. 139    
140.Gray F, Chrιtien F, Vallat-Decouvelaere AV, Scaravilli F. The changing pattern of HIV neuropathology in the HAART era. J Neuropathol Exp Neurol 2003;62:429-40.  Back to cited text no. 140 la Grandmaison GL, Carlier R, Chrιtien F, de Truchis P, Orlikowski D, Gray F. Burnt out varicella-zoster-virus encephalitis in an AIDS patient following treatment by highly active antiretroviral therapy. Clin Radiol 2005;60:613-7.  Back to cited text no. 141    
142.Strittmatter C, Lang W, Wiestler OD, Kleihues P. The changing pattern of human immunodeficiency virus- associated cerebral toxoplasmosis: A study of 46 postmortem cases. Acta Neuropathologica 1992;83:475-81.  Back to cited text no. 142    
143.Shelburne SA 3rd, Hamill RJ, Rodriguez-Barradas MC, Greenberg SB, Atmar RL, Musher DW, et al . Immune reconstitution inflammatory syndrome: Emergence of a unique syndrome during highly active antiretroviral therapy. Medicine (Baltimore) 2002;81:213-27.  Back to cited text no. 143    
144.144. Crump JA, Tyrer MJ, Lloyd-Owen SJ, Han LY, Lipman MC, Johnson MA. Miliary tuberculosis with paradoxical e xpansion of intracranial tuberculomas complicating immunodeficiency virus infection in a patient receiving highly active antiretroviral therapy. Clin Infect Dis 1998;26:1008-9.  Back to cited text no. 144    
145.Foudraine NA, Hovenkamp E, Notermans DW, Meenhorst PL, Klein MR, Lange JM, et al . Immunopathology as a result of highly active antiretroviral therapy in HIV-1-infected patients. AIDS 1999;13:177-84.  Back to cited text no. 145    
146.Jacobson MA, Zegans M, Pavan PR, O'Donnell JJ, Sattler F, Rao N, et al . Cytomegalovirus retinitis after initiation of highly active antiretroviral therapy. Lancet 1997;349:1143-5.  Back to cited text no. 146    
147.King MD, Perlino CA, Cinnamon J, Jernigan JA. Paradoxical recurrent meningitis following therapy of cryptococcal meningitis: An immune reconstitution syndrome after initiation of highly active antiretroviral therapy. AIDS 2002;13:724-6.  Back to cited text no. 147    
148.Wood ML, MacGinley R, Eisen DP, Allworth AM. HIV combination therapy: Partial immune restitution unmasking latent cryptococcal infection. AIDS 1998;12:1491-4.  Back to cited text no. 148    
149.Miralles P, Berenguer J, Lacruz C, Cosin J, Lopez JC, Padilla B, et al . Inflammatory reactions in progressive multifocal leukoencephalopathy after highly active antiretroviral therapy. AIDS 2001;15:1900-2.  Back to cited text no. 149    
150.Tantisiriwat W, Tebas P, Clifford DB, Powderly WG, Fichtenbaum CJ. Progressive multifocal leukoencephalopathy in patients with AIDS receiving highly active antiretroviral therapy. Clin Infect Dis 1998;28:1152-4.  Back to cited text no. 150    
151.Collazos J, Mayo J, Martinez E, Blanco MS. Contrast-enhancing progressive multifocal leukoencephalopathy as an immune reconstitution event in AIDS patients. AIDS 1999;13:426-8.  Back to cited text no. 151    
152.Hoffmann S, Horst HA, Albrecht H, Schlote W. Progressive multifocal leukoencephalopathy with unusual inflammatory response during antiretroviral treatment. J Neurol Neurosurg Psychiat 2003;74:1142-4.  Back to cited text no. 152    
153.Kotecha N, George MJ, Smith TW, Corvi F, Litofsky NS. Enhancing progressive multifocal leukoencephalopathy: An indicator of improved immune status? Am J Med 1998;105:541-3.  Back to cited text no. 153    
154.Langford TD, Letendre SL, Marcotte TD, Ellis RJ, McCutchan JA, Grant I, et al . Severe, demyelinating leukoencephalopathy in AIDS patients on antiretroviral therapy. AIDS 2002;16:1019-29.  Back to cited text no. 154    
155.Miller RF, Isaacson PG, Hall-Craggs M, Lucas S, Gray F, Scaravilli F, et al . Cerebral CD8+ lymphocytosis in HIV-1 infected patients with immune restoration induced by HAART. Acta Neuropathol 2004;108:17-23.  Back to cited text no. 155    
156.Smyth MJ, Kelly JM, Sutton VR, Davis JE, Browne KA, Sayers TJ, et al . Unlocking the secrets of cytoplasmic granule proteins. J Leukoc Biol 2001;70:18-29.  Back to cited text no. 156    
157.Venkatarama A, Pardo CA, McArthur JC, Kerr DA, Irani DN, Griffin JW, et al . Immune reconstitution inflammatory syndrome in the CNS of HIV-infected patients. Neurology 2006;67:383-8.  Back to cited text no. 157    
158.Vendrely A, Bienvenu B, Gasnault J, Thiebault JB, Salmon D, Gray F. Fulminant inflammatory leukoencephalopathy associated with HAART-induced immune restoration in AIDS-related progressive multifocal leukoencephalopathy. Acta Neuropathol 2005;109:449-55.  Back to cited text no. 158    
159.Breton G, Seilhean D, Chιrin P, Herson S, Benveniste O. Paradoxical intracranial cryptococcoma in a Human Immunodeficiency Virus-infected man being treated with combination Antiretroviral Therapy. Am J Med 2002;113:155-7.  Back to cited text no. 159    
160.Gray F, Bazille C, Adle-Biassette H, Mikol J, Moulignier A, Scaravilli F. Central nervous system immune reconstitution disease in AIDS patients receiving highly active antiretroviral treatment. J Neurovirol 2005;11:16-22.  Back to cited text no. 160    
161.Valcour V, Pail R. HIV infection and dementia in older adults. Clin Infect Dis 2006;42:1449-54.  Back to cited text no. 161    
162.Brew BJ. Evidence for a change in AIDS dementia complex in the era of highly active antiretroviral therapy and the possibility of new forms of AIDS dementia complex. AIDS 2004;18:S75-8.  Back to cited text no. 162    
163.Anthony IC, Ramage SN, Carnie FW, Simmonds P, Bell JE. Influence of HAART on HIV-related CNS disease and neuroinflammation. J Neuropathol Exp Neurol 2005;64:529-36.  Back to cited text no. 163    
164.Mercie P, Thiebaut R, Aurillac-Lavignolle V, Pellegrin JL, Yvorra-Vives MC, Cipriano C, et al . Carotid intima-media thickness is slightly increased over time in HIV-1-infected patients. HIV Med 2005;6:380-7.  Back to cited text no. 164    
165.Green DA, Masliah E, Vinters HV, Beizai P, Moore DJ, Achim CL. Brain deposition of beta-amyloid is a common pathologic feature in HIV-positive patients. AIDS 2005;19:407-11.  Back to cited text no. 165    
166.Rempel HC, Pulliam L. HIV-1 tat inhibits neprelysin and elevates amyloid beta. AIDS 2005;19:127-35.  Back to cited text no. 166    
167.Brew BJ, Pemberton L, Blennow K, Wallin A, Hagberg L. CSF amyloid beta 42 and tau levels correlate with AIDS dementia complex. Neurology 2005;65:1490-2.  Back to cited text no. 167    


  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]

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