title: Loss of cerebellar neurons in the progression of lentiviral disease: effects of CNS-permeant antiretroviral therapy.
abstract: The majority of investigations on HIV-associated neurocognitive disorders (HAND) neglect the cerebellum in spite of emerging evidence for its role in higher cognitive functions and dysfunctions in common neurodegenerative diseases.
  
  
  
  We systematically investigated the molecular and cellular responses of the cerebellum as contributors to lentiviral infection-induced neurodegeneration, in the simian immunodeficiency virus (SIV)-infected rhesus macaque model for HIV infection and HAND. Four cohorts of animals were studied: non-infected controls, SIV-infected asymptomatic animals, and SIV-infected AIDS-diseased animals with and without brain-permeant antiretroviral treatment. The antiretroviral utilized was 6-chloro-2',3'-dideoxyguanosine (6-Cl-ddG), a CNS-permeable nucleoside reverse transcriptase inhibitor. Quantitation of granule cells and Purkinje cells, of an established biomarker of SIV infection (gp41), of microglial/monocyte/macrophage markers (IBA-1, CD68, CD163), and of the astroglial marker (GFAP) were used to reveal cell-specific cerebellar responses to lentiviral infection and antiretroviral therapy (ART). The macromolecular integrity of the blood brain barrier was tested by albumin immunohistochemistry.
  
  
  
  Productive CNS infection was observed in the symptomatic stage of disease, and correlated with extensive microglial/macrophage and astrocyte activation, and widespread macromolecular blood brain barrier defects. Signs of productive infection, and inflammation, were reversed upon treatment with 6-Cl-ddG, except for a residual low-grade activation of microglial cells and astrocytes. There was an extensive loss of granule cells in the SIV-infected asymptomatic cohort, which was further increased in the symptomatic stage of the disease and persisted after 6-Cl-ddG (administered after the onset of symptoms of AIDS). In the symptomatic stage, Purkinje cell density was reduced. Purkinje cell loss was likewise unaffected by 6-Cl-ddG treatment at this time.
  
  
  
  Our findings suggest that neurodegenerative mechanisms are triggered by SIV infection early in the disease process, i. e., preceding large-scale cerebellar productive infection and marked neuroinflammation. These affect primarily granule cells early in disease, with later involvement of Purkinje cells, indicating differential vulnerability of the two neuronal populations. The results presented here indicate a role for the cerebellum in neuro-AIDS. They also support the conclusion that, in order to attenuate the development of motor and cognitive dysfunctions in HIV-positive individuals, CNS-permeant antiretroviral therapy combined with anti-inflammatory and neuroprotective treatment is indicated even before overt signs of CNS inflammation occur.
authors.affiliation: Molecular Neuroscience, Institute of Anatomy and Cell Biology, Philipps University Marburg, Robert-Koch-Str. 8, 35032, Marburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wächter
authors.affiliation: Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, NIH, Bethesda, MD, USA.
authors.forename: Lee E
authors.initials: LE
authors.lastname: Eiden
authors.affiliation: Molecular Neuroscience, Institute of Anatomy and Cell Biology, Philipps University Marburg, Robert-Koch-Str. 8, 35032, Marburg, Germany.
authors.forename: Nedye
authors.initials: N
authors.lastname: Naumann
authors.affiliation: Molecular Neuroscience, Institute of Anatomy and Cell Biology, Philipps University Marburg, Robert-Koch-Str. 8, 35032, Marburg, Germany.|Experimental Neurology, Department of Neurology, Philipps University Marburg, Marburg, Germany.
authors.forename: Candan
authors.initials: C
authors.lastname: Depboylu
authors.affiliation: Molecular Neuroscience, Institute of Anatomy and Cell Biology, Philipps University Marburg, Robert-Koch-Str. 8, 35032, Marburg, Germany. weihe@staff.uni-marburg.de.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Weihe
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D044966:Anti-Retroviral Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D015703:Antigens, CD / Q000378:metabolism; D002135:Calcium-Binding Proteins; D016022:Case-Control Studies; D002531:Cerebellum / Q000473:pathology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015224:Dideoxynucleosides / Q000494:pharmacology / Q000627:therapeutic use; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005911:Gliosis / Q000209:etiology / Q000821:virology; D015700:HIV Envelope Protein gp41 / Q000378:metabolism; D015658:HIV Infections / Q000188:drug therapy* / Q000473:pathology*; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D008840:Microfilament Proteins; D017628:Microglia / Q000187:drug effects / Q000473:pathology; D009410:Nerve Degeneration / Q000188:drug therapy / Q000209:etiology / Q000821:virology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism
chemical_list: C095793:6-chloro-2',3'-dideoxyguanosine; C112986:AIF1 protein, human; D044966:Anti-Retroviral Agents; D015703:Antigens, CD; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D015224:Dideoxynucleosides; D005904:Glial Fibrillary Acidic Protein; D015700:HIV Envelope Protein gp41; D008840:Microfilament Proteins
keywords: Antiretroviral therapy; Dementia; Human immunodeficiency virus (HIV); Neuro-AIDS; Neurodegeneration