Elevated peripheral benzodiazepine receptor expression in simian immunodeficiency virus encephalitis.
Measurement of central nervous system (CNS) expression of the peripheral benzodiazepine receptor (PBR), a microglia and macrophage activation marker, by positron emission tomography (PET) would aid clinical management of human immunodeficiency virus (HIV)-infected patients. To evaluate the utility of examining PBR expression in the CNS as a cellular activation marker in HIV CNS disease, PBR levels were measured in frontal cortex of simian immunodeficiency virus (SIV)-infected macaques with encephalitis and uninfected animals via PK11195 ligand autoradiography. [(3)H]-(R)-PK11195 binding to both grey matter (P =.017) and white matter (P =.038) was significantly higher in animals with SIV encephalitis (n = 10) versus control animals (n = 3). When PK11195 binding was compared with other microglial/macrophage activation markers (obtained via quantitative image analysis), a strong, significant association was found for both HAM56 (P =.004) and KP-1 (anti-CD68; P =.006) immunostaining in white matter. In contrast, grey matter PK11195 binding did not correlate with HAM56 (P =.46), KP-1 (P =.06), or glial fibrillary acidic protein (GFAP) immunostaining for astrocytic activation (P =.09). The regional nature of these increases in activation within the brain illustrates the crucial need to focus functional neuroimaging analyses of HIV-infected individuals on subcortical white matter to assess activation of microglia and macrophages.
Mankowski
Joseph L
JL
Department of Comparative Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. jmankows@jhmi.edu
Queen
Suzanne E
SE
Tarwater
Patrick J
PJ
Adams
Robert J
RJ
Guilarte
Tomas R
TR
D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D018792:Encephalitis, Viral / Q000276:immunology / Q000378:metabolism; D005911:Gliosis / Q000378:metabolism / Q000821:virology; D007546:Isoquinolines / Q000378:metabolism / Q000494:pharmacology; D008254:Macaca nemestrina; D008264:Macrophages / Q000378:metabolism / Q000821:virology; D017628:Microglia / Q000378:metabolism / Q000821:virology; D011963:Receptors, GABA-A / Q000378:metabolism*; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000378:metabolism*; D015302:Simian Immunodeficiency Virus
D000970:Antineoplastic Agents; D007546:Isoquinolines; D011963:Receptors, GABA-A; C037850:PK 11195