The Effect of Simian Immunodeficiency Virus Infectionin Vitroandin Vivoon the Cytokine Production of Isolated Microglia and Peripheral Macrophages from Rhesus Monkey

AbstractMicroglia are the major target for human immunodeficiency virus (HIV) infection within the central nervous system. Because only a few cells are productively infected, it has been suggested that an aberrant cytokine production by this cell population may be an indirect mechanism leading to the development of neurological disorders in HIV-infected patients. Therefore we decided to study the secretion pattern of several interleukins (IL) by microglial cells and peripheral blood macrophages isolated from uninfected and simian immunodeficiency virus (SIV)-infected Rhesus monkeys. We found that uninfected, unstimulated primate microglia produce more IL-6 and less TNFα than peripheral blood macrophages, but generate comparable levels of IL-1β and IL-8. After infection with SIVin vitro,synthesis of all cytokines tested is increased compared to uninfected cultures and to peripheral blood macrophages. Microglia isolated from infected animals produce more IL-8 and TNFα than the uninfected cultures and display a strongly increased capacity to secrete TNFα upon stimulation with lipopolysaccharide. In addition, production of IL-6 byin vivo-infected microglia increases with time in culture to very high levels despite the fact that only a few cells contained replicating virus. These findings clearly show that the cytokine production of microglia is impaired after SIV infection bothin vitroandin vivoand that a low level of viral replication is sufficient for these alterations to occur. In conclusion, the results of this study further support a possible role of cytokines in the pathogenesis of neuro-AIDS