HIV-1 in postmortem brain tissue from patients with AIDS: a comparison of different detection techniques

Subtype C HIV-1 reservoirs throughout the body in ART-suppressed individuals

Subtype B HIV-1 reservoirs have been intensively investigated, but reservoirs in other subtypes and how they respond to antiretroviral therapy (ART) is substantially less established. To characterize subtype C HIV-1 reservoirs, we implemented postmortem frozen, as well as formalin fixed paraffin embedded (FFPE) tissue sampling of central nervous system (CNS) and peripheral tissues. HIV-1 LTR, gag, envelope (env) DNA and RNA was quantified using genomic DNA and RNA extracted from frozen tissues. RNAscope was used to localize subtype C HIV-1 DNA and RNA in FFPE tissue. Despite uniform viral load suppression in our cohort, PCR results showed that subtype C HIV-1 proviral copies vary both in magnitude and tissue distribution, with detection primarily in secondary lymphoid tissues. Interestingly, the appendix harbored proviruses in all subjects. Unlike subtype B, subtype C provirus was rarely detectable in the CNS, and there was no detectable HIV-1 RNA. HIV-1 RNA was detected in peripheral lymphoid tissues of 6 out of 8 ART-suppressed cases. In addition to active HIV-1 expression in lymphoid tissues, RNAscope revealed HIV RNA detection in CD4-expressing cells in the appendix, suggesting that this tissue was a previously unreported potential treatment-resistant reservoir for subtype C HIV-1.

Susceptibility of human testis to human immunodeficiency virus-1 infection in situ and in vitro

Semen represents the main vector for human immunodeficiency virus (HIV) dissemination worldwide and has been shown to harbor replication-competent virus despite otherwise effective highly active anti-retroviral therapy, which achieves undetectable viral load in plasma. Despite this, the origin of seminal HIV particles remains unclear, as does the question of whether the male genital tract organs contribute virus to semen. Here we investigated the presence of HIV receptors within the human testis using immunohistochemistry and quantitative real-time polymerase chain reaction. We also analyzed the infectivity of a dual tropic HIV-1 strain in an organotypic culture, as well as the impact of viral exposure on testosterone production. Our study establishes that CXCR4+, CCR5+, CD4+, and DC-SIGN+ cells are present within the interstitial tissue of human testis and that these molecules persist throughout our organotypic culture. Our data also reveal that the human testis is permissive to HIV-1 and supports productive infection, leaving testosterone production apparently unaffected. Infected cells appeared to be testicular macrophages located within the interstitial tissue. That the testis itself represents a potential source of virus in semen could play a role in preventing viral eradication from semen because this organ constitutes a pharmacological sanctuary for many current antiretrovirals.

Oxandrolone, used for treatment of wasting disease in HIV-1-infected patients, does not diminish the antiviral activity of deoxynucleoside analogues in lymphocyte and macrophage cell cultures

Antiviral agents are the primary therapy for patients infected with HIV-1. However, supportive therapies are often necessary in addition to antiviral drugs because of the devastating wasting process associated with HIV-1 infection and AIDS. Oxandrolone, an anabolic steroid, is used in promoting weight gain and, most important lean body mass (LBM), in patients with HIV-1 disease. We investigated whether oxandrolone interferes with the antiviral activity of zidovudine (ZDV), dideoxyinosine (ddI), and dideoxycytidine (ddC) on HIV-1 replication in peripheral blood lymphocytes and macrophage-monocytes. The nucleoside analogues had nanomolar 50% inhibitory concentrations (IC50) in peripheral lymphocytes. Combinations of nucleoside analogues and oxandrolone did not result in increased IC50 values. Oxandrolone used alone exhibited micromolar IC50 values in peripheral blood lymphocytes. Lack of interference was consistent for nucleoside concentrations up to 5 microM and for oxandrolone concentrations up to 100 microM in several combinations of drugs, viral strains, and peripheral lymphocytes and macrophages. We conclude that oxandrolone can be used for the promotion of weight gain in patients with AIDS-related wasting without interference with the antiviral effects of ZDV, ddI, or ddC.

HIV-1 proviral DNA load across neuroanatomic regions of individuals with evidence for HIV-1-associated dementia

A definitive relation between HIV-1 load and the clinical diagnosis of HIV-1-associated dementia (HAD) has not yet been established. Knowledge of the neuroanatomic distribution of HIV-1 load in the brain of individuals with HAD and HIV-1 encephalitis may facilitate elucidation of this relation. Nine individuals with AIDS were analyzed postmortem by three independent methods with each assessment performed blinded to the others: 1) a neuropsychiatric review of clinical records for evidence of possible HAD, 2) HIV-1 DNA load determination by quantitative polymerase chain reaction (PCR) across several neuroanatomic regions, and 3) a pathologic examination for diagnosis of HIV-1 encephalitis by immunohistochemical techniques. Of eight AIDS cases with clinical records sufficient for neuropsychiatric review, seven were shown to have evidence for HAD. HIV-1 DNA was detected and quantified in specimens from all of the medial temporal lobe regions analyzed but was not detectable in the frontal lobe at the same level of sensitivity in two of these cases (<1 per 1000 cellular genomes). HIV-1 DNA load in the medial temporal lobe region was significantly larger than that in the frontal lobe. Only four of seven cases with evidence for HAD were also diagnosed with HIV-1 encephalitis.

A rapid method for comparative quantitative polymerase chain reaction of HIV-1 proviral DNA extracted from cryopreserved brain tissues

The quantitative polymerase chain reaction (PCR) method devised by Fujimura and Bockstahler (1995) was modified for rapid determination of distribution of HIV-1 proviral DNA load in AIDS brains. It was used for analysis of an association with HIV-1 associated dementia and HIV-1 encephalitis (Fujimura et al., 1997). The method has wider applicability for comparative studies of viral DNA load based on PCR amplification. The method is applicable under conditions where target DNA and its PCR-amplified product increase proportionally. An equation was derived to obtain the number of copies of HIV-1 DNA per cellular genome from the amount of PCR amplified product of a tissue specimen DNA. The equalizing constant is the reciprocal of the slope of the amplification of the HIV-1 proviral DNA sequence of the standard cellular DNA included in each experiment. The intercept of the equation is zero.

HIV-1 heterogeneity and cytokines. Neuropathogenesis

Mild manifestations (HIV-1 associated minor cognitive/motor disorder), severe manifestations (HIV-1 associated dementia complex and HIV-1 associated myelopathy), and sensory neuropathy are consequences of HIV-1 infection. Our goal is to elucidate the role of HIV-1 in the complications of AIDS including cytokine immunopathology and HIV-1 DNA sequence variants. We have examined the brain and sensory ganglia from 60 AIDS patients and 20 seronegative controls using PCR, DNA sequencing of the HIV-1 envelope protein (env), in situ hybridization (ISH), and immunohistochemistry (IHC). Using our combined ISH-IHC technique, we could identify different types of cells and HIV-1 simultaneously in cryostat and paraffin sections. We found HIV-1 predominantly in macrophage/microglia in brain. In dorsal root ganglia (DRG) we found rare macrophages infected with HIV-1 and neurons and interstitial cells (including macrophages) which were apoptotic. Cytokines were detected in mononuclear and endothelial cells near neurons. We achieved single copy sensitivity detecting HIV-1 in nervous tissue using nested PCR. We sequenced HIV-1, DNA from 3 intravenous drug users (IDUs): from brain, CSF, and blood. PCR amplification was followed by cloning and then sequencing the HIV-1 insert: V1-V5 regions of the envelope (env) gene. We found that the env genes had increased sequence variation compared to the literature, cDNA sequences derived from RNA were less heterogeneous than clones derived from DNA from the same specimens, clones derived from brain are more closely related (show restricted heterogeneity) compared to clones from blood and CSF from the same patients. Patient 149 clones we examined to date did not correspond to any of the designated subtypes (A-F) of HIV-1 based on the DNA sequences of the C2-V3 regions. Finally, the HIV-1 RNA produced in these tissues is derived from a minority of DNA clones. Although HIV-1 infected macrophages are not entirely responsible for pathology in the brain and less so in sensory ganglia, some of the products of infection, cytokines, are more widespread in these tissues. Furthermore, HIV-1 strains infecting the brain appear to exhibit restricted heterogeneity compared to autologous CSF and blood and these strains may be associated with cytokines and pathology. HIV-1 strains that infect nervous tissue and cytokines produced in this tissue may effect neuropathogenesis, in vivo, in spite of low levels of local HIV-1 infection. We attempt to delineate, here, common sequence variations in HIV-1 isolates in the hope of developing future therapeutic strategies.

Role of immune activation and cytokine expression in HIV-1-associated neurologic diseases

Central nervous system (CNS) involvement is common during human immunodeficiency virus type-1 (HIV-1) infection. The neurologic disease of the CNS most frequently observed during acquired immunodeficiency syndrome (AIDS) is HIV-1-associated cognitive/motor complex or AIDS dementia complex (ADC), which is most likely a direct consequence of HIV-1 infection of the CNS. The peripheral nervous system (PNS) is also affected in HIV-1-infected individuals and there are several features of immune- and cytokine-related pathogenesis in both the CNS and PNS that are reviewed. Several lines of evidence demonstrate aspects of immune activation in the CNS and peripheral nervous system (PNS) of HIV-1-infected individuals. The relative paucity of HIV-1 expression in contrast to widespread functional and pathologic changes in the CNS and PNS of AIDS patients, and the lack of evidence of productive infection of HIV-1 in neuronal cells in vivo lead to the possibility of indirect or immunopathogenic mechanisms for HIV-1-related neurologic diseases. Proposed mechanisms of neuronal and glial cell damage are injury of oligodendrocytes by tumor necrosis factor-alpha (TNF-alpha) released from activated macrophage/microglia, calcium-dependent excitoneurotoxicity induced by gp120 HIV-1 envelope protein, N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity by quinolinic acid (a product of activated macrophages), cell injury by HIV-1-specific cytotoxic T cells, and apoptosis of oligodendrocytes or neurons triggered by interaction between cell surface receptors and HIV-1 gp120 protein. Common to those mechanisms is the dependence on cellular activation with expression of proinflammatory cytokines (TNF-alpha, interleukin-1). Amplification of activation signals through the cytokine network by macrophage/astrocyte/endothelial cell interactions, and cell-to-cell contact between activated macrophages and neural cells by upregulation of adhesion molecules dramatically enhances the toxic effect of macrophage products. Expression of immunosuppressive cytokines such as interleukin-4, interleukin-6, and transforming growth factor-beta is also increased in the CNS and PNS of HIV-1-infected patients. This may serve as neuroprotective and regenerative mechanism against insults to nervous system tissue.

Histopathologic features in the central nervous system of 400 acquired immunodeficiency syndrome cases: implications of rates of occurrence

Histopathologic lesions in the central nervous system (CNS) of 400 autopsy cases of the acquired immunodeficiency syndrome (AIDS) collected from 1982 to 1990 were studied. Lesions most closely associated with human immunodeficiency virus (HIV) infection in the CNS (perivascular macrophages, nodular encephalomyelitis, diffuse leukoencephalopathy, necrotizing encephalitis, and long-tract degeneration) were found in 20% of the cases. The group of vascular and inflammatory lesions and of opportunistic infections was seen in 25% of cases. These two lesion groups were found together in 32% of cases, and none of these lesions was present in 23% of cases (most of the latter having no significant CNS lesions). Length of survival increased in the last group of 100 cases compared with the first 300 cases. The homosexual and bisexual risk groups showed continuously increasing lengths of survival for each category of HIV-associated CNS lesions throughout the study, while the lengths of survival in the other risk groups varied. Patients in the last group of 100 autopsy cases with any HIV-associated lesion survived longer than patients without these lesions. The AIDS patients with no CNS lesions had the shortest mean length of survival. The results suggest that although survival is prolonged as specific therapy is given, there is an increase in CNS lesions in AIDS patients with longer survival. This may indicate that CNS lesions in AIDS are generally dependent on systemic disease progression over many months as immune function decreases.