Leanne C. Huysentruyt

HIV-1 phylogenetic analysis shows HIV-1 transits through the meninges to brain and peripheral tissues

Brain infection by the human immunodeficiency virus type 1 (HIV-1) has been investigated in many reports with a variety of conclusions concerning the time of entry and degree of viral compartmentalization. To address these diverse findings, we sequenced HIV-1 gp120 clones from a wide range of brain, peripheral and meningeal tissues from five patients who died from several HIV-1 associated disease pathologies. High-resolution phylogenetic analysis confirmed previous studies that showed a significant degree of compartmentalization in brain and peripheral tissue subpopulations. Some intermixing between the HIV-1 subpopulations was evident, especially in patients that died from pathologies other than HIV-associated dementia. Interestingly, the major tissue harboring virus from both the brain and peripheral tissues was the meninges. These results show that (1) HIV-1 is clearly capable of migrating out of the brain, (2) the meninges are the most likely primary transport tissues, and (3) infected brain macrophages comprise an important HIV reservoir during highly active antiretroviral therapy.

Hypothesis : are neoplastic macrophages / microglia present in glioblastoma multiforme ?

Most malignant brain tumours contain various numbers of cells with characteristics of activated or dysmorphic macrophages/microglia. These cells are generally considered part of the tumour stroma and are often described as TAM (tumour-associated macrophages). These types of cells are thought to either enhance or inhibit brain tumour progression. Recent evidence indicates that neoplastic cells with macrophage characteristics are found in numerous metastatic cancers of non-CNS (central nervous system) origin. Evidence is presented here suggesting that subpopulations of cells within human gliomas, specifically GBM (glioblastoma multiforme), are neoplastic macrophages/microglia. These cells are thought to arise following mitochondrial damage in fusion hybrids between neoplastic stem cells and macrophages/microglia.

Perspectives on the mesenchymal origin of metastatic cancer

Emerging evidence suggests that many metastatic cancers arise from cells of the myeloid/macrophage lineage regardless of the primary tissue of origin. A myeloid origin of metastatic cancer stands apart from origins involving clonal evolution or epithelial–mesenchymal transitions. Evidence is reviewed demonstrating that numerous human cancers express multiple properties of macrophages including phagocytosis, fusogenicity, and gene/protein expression. It is unlikely that the macrophage properties expressed in metastatic cancers arise from sporadic random mutations in epithelial cells, but rather from damage to an already existing mesenchymal cell, e.g., a myeloid/macrophage-type cell. Such cells would naturally embody the capacity to express the multiple behaviors of metastatic cells. The view of metastasis as a myeloid/macrophage disease will impact future cancer research and anti-metastatic therapies.

Distinct Patterns of HIV-1 Evolution within Metastatic Tissues in Patients with Non-Hodgkins Lymphoma

Despite highly active antiretroviral therapy (HAART), AIDS related lymphoma (ARL) occurs at a significantly higher rate in patients infected with the Human Immunodeficiency Virus (HIV) than in the general population. HIV-infected macrophages are a known viral reservoir and have been shown to have lymphomagenic potential in SCID mice; therefore, there is an interest in determining if a viral component to lymphomagenesis also exists. We sequenced HIV-1 envelope gp120 clones obtained post mortem from several tumor and non-tumor tissues of two patients who died with AIDS-related Non-Hodgkins lymphoma (ARL-NH). Similar results were found in both patients: 1) high-resolution phylogenetic analysis showed a significant degree of compartmentalization between lymphoma and non-lymphoma viral sub-populations while viral sub-populations from lymph nodes appeared to be intermixed within sequences from tumor and non-tumor tissues, 2) a 100-fold increase in the effective HIV population size in tumor versus non-tumor tissues was associated with the emergence of lymphadenopathy and aggressive metastatic ARL, and 3) HIV gene flow among lymph nodes, normal and metastatic tissues was non-random. The different population dynamics between the viruses found in tumors versus the non-tumor associated viruses suggest that there is a significant relationship between HIV evolution and lymphoma pathogenesis. Moreover, the study indicates that HIV could be used as an effective marker to study the origin and dissemination of lymphomas in vivo.

The role of macrophages in the development and progression of AIDS-related non-Hodgkin lymphoma

Despite HAART, patients infected with HIV develop NHL at a significantly higher level than the noninfected population. The primary difference between lymphoma in non‐HIV‐infected individuals and those with ARL is that ARL is consistently high‐grade and metastatic. The emergence of ARL is associated with the presence of macrophage viral reservoirs, similar to what has been observed for HAD. HIV‐infected macrophages, as seen by histology and HIV p24 staining, are present in approximately half of ARLs. Macrophage reservoirs recruit additional immune cells, including monocytes/macrophages, through the release of chemoattractants. Additionally, TAM are known to promote tumor progression for most cancer types, including lymphomas. This review will highlight and discuss the role of macrophage viral reservoirs in the development and progression of ARLs and hopefully, shed light on this new and interesting field.

HIV-1 Nef in Macrophage-Mediated Disease Pathogenesis

Combined anti-retroviral therapy (cART) has significantly reduced the number of AIDS-associated illnesses and changed the course of HIV-1 disease in developed countries. Despite the ability of cART to maintain high CD4+ T-cell counts, a number of macrophage-mediated diseases can still occur in HIV-infected subjects. These diseases include lymphoma, metabolic diseases, and HIV-associated neurological disorders. Within macrophages, the HIV-1 regulatory protein “Nef” can modulate surface receptors, interact with signaling pathways, and promote specific environments that contribute to each of these pathologies. Moreover, genetic variation in Nef may also guide the macrophage response. Herein, we review findings relating to the Nef–macrophage interaction and how this relationship contributes to disease pathogenesis.

HIV-1 Nef Protein Visits B-Cells via Macrophage Nanotubes: A Mechanism for AIDS-Related Lymphoma Pathogenesis?

This letter refers to the recent demonstration that HIV-1 infected macrophages form specialized conduits that connect to B-cells (1). The conduit selectively transports the HIV-1 nef protein, providing nef with numerous means to interfere with cellular processes. Currently, no consideration of the connection between the conduit and the development of AIDS-related lymphoma (ARL) has been offered. ARL is one of the primary causes of death in the HIV-infected population and is related to B-cell proliferation and activation. In this letter we discuss several studies that link HIV-infected macrophages and specific forms of the nef protein to the development of ARL. The conduits discovered by Xu et al. may lead to a better understanding of how HIV infection results in lymphomagenesis.

The prevalence of HIV-1 DNA in AIDS-related lymphoma and Kaposi Sarcoma throughout the AIDS epidemic

Background Chronic inflammation is linked to tumorigenesis for many cancer types and likely contributes to tumor development in the HIV-infected patient population. AIDSrelated lymphoma (ARL) and Kaposi Sarcoma (KS), two AIDS-defining cancers, are associated with the tumor viruses EBV and KSHV, respectively. However, EBV is only detectable in ~40% of ARLs and KSHV alone is not sufficient for KS development. Recent studies have shown that HIV is localized to tumor associated macrophages (TAM), not malignant B cells, in a portion of EBV-negative ARLs suggesting, that HIV infected TAM may play ar ole in tumorigenesis. The goal of this research was to determine the prevalence of HIV+ ARL and KS throughout the AIDS epidemic and examine tumor associated HIV for unique genetic signatures. Material and methods Whole genomic amplified DNA from ARL and KS biopsies was used for quantitative HIV gag gene amplification. The 3’ env-LTR segment of HIV-1 genomes from tumor and non-tumor tissues from two patients that died of ARL were sequenced and Bayesian phylogenies were inferred using BEAST. All specimens were provided by the AIDS and Cancer Specimen Resource. Results Of the 119 ARL and 91 KS biopsies, 45% and 40% contained detectable HIV-1 DNA, respectively. There was a significant decrease in the prevalence of HIV-1 DNA positive ARL and KS cases in the post-HAART era (after 1996; ARL=39%, KS=16.7) as compared to preHAART (ARL=54%, KS=45%). Our data suggest the overall amount of HIV DNA is less in tumor biopsies from the post-HAART era. A subset of ARL contained extremely high levels of HIV-1 DNA (~1 copy/cell). In addition, visceral KS had a higher prevalence of HIV-1 DNA (51.9%) as compared to skin KS (30.7%). HIV sequence evolution analysis of metastatic ARLs revealed that HIV was compartmentalized within sites of lymphoma and was distinct from HIV present in nonlymphoma sites. Conclusions The prevalence of HIV-1 DNA positive ARLs declined in the post-HAART era, but not to the same extent as KS, consistent with the incidence of both tumor types in the post-HAART era. Higher prevalence of HIV-1 DNA in visceral sites of KS and lymphoma specific-HIV sequences in sites of metastatic lymphoma suggests that HIV, especially HIV infected macrophages, may play a role in the pathogenesis of KS and ARL disease progression. Additionally, HIV-infected macrophages are a source of chronic inflammation that may further enhance tumorigenesis. Our data suggest a tumor specific form of HIV may be evolving within individuals who develop ARL.

Abstract 2714: High HIV-1 DNA copy number defines a unique subset of AIDS-related lymphoma

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Despite highly active antiretroviral therapy (HAART), the risk of developing non-Hodgkin lymphoma is ∼100X greater in the HIV-infected population compared to non-infected individuals and AIDS-related lymphoma (ARL) prevalence is expected to rise in the future. Preliminary reports have suggested that some ARLs contain HIV-infected macrophages that may contribute to ARL pathogenesis. A recent study evaluating HIV sequence evolution in the contest of metastatic ARL found lymphoma specific HIV compartmentalized within sites of lymphoma that was distinct from HIV present in non-lymphoma sites (Salemi et al, PLOSone Dec 3, 2009). These data suggested the existence of a lymphoma specific form of HIV evolving within individuals who develop ARL. The goal of this research was to determine the prevalence and quantity of HIV-1 DNA in 119 ARL biopsies from the entire span of the HIV epidemic (1982-2007) by utilizing whole genomic amplified (WGA) ARL DNA, provided by the AIDS and Cancer Specimen Resource (ACSR). The presence of HIV-1 DNA was determined by quantitative amplification of the HIV gag gene using single copy genes to define HIV copy numbers per genomic equivalent. Of the 119 ARL cases, 45% contained detectable levels of HIV-1 DNA (> 1 copy per 30,000 cells). The relationship between HIV DNA presence and tumor immunophenotype was determined using ARL data from the ACSR on the cases studied. The level of HIV per genomic equivalent in the 45% HIV DNA positive cases was as high as one/cell equivalent. There was a significant (p<0.01) decrease in the prevalence of HIV-1 DNA-positive ARL cases post-HAART (after 1996; 39%) as compared to pre-HAART (before 1996; 54%). Additionally, our data suggest that the overall amount of HIV-1 DNA present in ARLs was less in the post-HAART era when compared to the pre-HAART era. The HIV DNA positive cases fell into a positive outcome category (MUM1 negative and CD10 positive) based on lymphoma immunophenotype literature (p< 0.02). Thus, a subset of ARLs containing high levels of HIV DNA, falls into a better outcome category based on immunophenotype data and may represent a different lymphoma pathogenic process. The existence of lymphoma specific variants of HIV is currently under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2714. doi:10.1158/1538-7445.AM2011-2714

The HIV nef protein within ARL is genetically and structurally distinct from those in the brain of patients with HAD

Background Despite antiretroviral therapy, macrophages remain significant cellular reservoirs for HIV infection. Two fatal macrophage-mediated diseases still occur at a much higher rate in the HIV-infected and HAART-treated population: (1) AIDS-related lymphoma (ARL), a noninflammatory disease, and (2) HIV-associated dementia (HAD), an inflammatory disease. The frequency of HIVinfected macrophages in ARL is 50%. Macrophages are the primary HIV-infected cells in the brain. The mechanisms that lead to the development of these diseases are not understood. Because certain subtypes of HIV are associated with a higher prevalence of HAD, a viral genetic determinant for HAD development is likely. On the other hand, ARL development occurs fairly consistently across multiple HIV subtypes and genetic analysis has clearly differentiated ARL tissue-associated HIV from non-ARL tissue HIV within individuals. These facts raise two questions: (1) Are there tumor-specific genetic differences among HIV proteins that could influence the macrophage to accelerate ARL development? (2) How might HAD-associated and ARL-associated viruses differ at the genetic and structural levels? Our goal was to analyze HAD and ARL viral sequences and determine whether a disease association could be identified within viral proteins. Methods