HIV integration within activation loci is characteristic of dominant insertion sites within the diseased tissues of patients with HIV associated dementia and AIDS related lymphoma

M. McGrath¹, X. Jin², S Yu², C. Green², M. Weinstein¹, and K. Mack²; ¹University of California, San Francisco, CA., ²SLIL Biomedical Corporation, Menlo Park, CA (USA)

Background: In spite of aggressive anti-retroviral therapy, patients with HIV infection still develop AIDS-related lymphoma (ARL) and neuro-cognitive disorders such as HIV-associated dementia (HAD). Earlier studies on AIDS dementia and recent studies on AIDS-related lymphoma have suggested roles for activated and potentially HIV-infected macrophages in the pathogenesis of these respective diseases. The goal of the current pilot study was to test whether HIV DNA would be elevated in diseased tissues as compared to controls and to map dominant HIV insertion sites within these tissues. Material and Methods: AIDS dementia and lymphoma tissue was obtained from the AIDS and Cancer Specimen Resource (ACSR), web site: http://acsr.ucsf.edu. The level of HIV DNA present within extracted tissue DNA was compared with the single copy c-jun gene and quantitation was determined using LightCycler technology (Roche).  HIV insertion site mapping was accomplished using inverse PCR techniques. Laser capture microdissection (LCM) was used in several cases to identify the immunophenotype of cells containing integrated HIV. Results: Eight cases (15 sites) of AIDS lymphoma and five cases (involved vs. uninvolved) of AIDS dementia were studied in comparison to controls.  HIV DNA was present at relatively high copy numbers (range: 1 HIV/ 6- 8626 genomic equivalents (GE)) in both classes of disease with mean values in HAD (1 HIV/42 GE in involved tissue vs. < 1/10,000 uninvolved) being higher than in ARL (1 HIV/1200 GE in ARL tissue vs. < 1/10,000 in control nodes). Insertion site mapping was performed on DNA from both classes of disease and 85 percent of those insertion sites mapped to genomic regions encoding signal transduction, transcriptional activation, proliferation, and receptor activation genes.  LCM performed on both diseases localized these types of insertion sites to tissue-associated macrophages. Conclusion: The high frequency of HIV integration within gene activation loci in tissue-associated macrophages suggests a mechanism of HIV persistence in vivo. Macrophage activation is generally associated with downregulation of programmed cell death genes potentially allowing cells containing activation site insertions to persist, and within diseased tissues, contribute to pathogenic changes observed in AIDS lymphoma and dementia.