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Published on: August 15, 2012
Characterization of cultured microglia that can be infected by HIV-1
A V Albright1, J T Shieh, M J O'Connor
1Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, PA 19104-6146, USA.
Abstract:
Parenchymal microglia are targets of HIV infection. We, as well as others, have used in vitro microglia culture systems to study the tropism and replication of HIV. Characterization of perivascular and parenchymal microglia surface markers in vivo, in vitro, and ex vivo, has led to the understanding that these cell populations are different, and data from both the HIV and SIV models support the hypothesis that they may play different roles in infection of the CNS. We determined that human adult parenchymal microglia cultured from temporal lobe tissue for use in HIV replication studies, were CD11c+, CD45+, CD68+, CD14- when cultured with standard serum/cytokine-supplemented media. To determine the influence of serum and cytokines on HIV replication in microglia, we designed a new protocol for culturing microglia, and compared the results obtained with this protocol with the standard approach previously described. Microglia cultured in the presence of a 'feeder' layer of glial cells and in the absence of serum and cytokines expressed the same surface markers as pure microglia (>95%) cultured in supplemented media. However, pure microglia cultured in the absence of both serum/cytokines supplements and other glial cells, did not have characteristic microglial morphology and did not support HIV replication to as high a level. Lastly, we determined that unlike monocytes, ex vivo parenchymal microglia were capable of supporting HIV replication.
Insights
Parenchymal microglia are targets for HIV infection. New culture methods show that pure microglia, without serum or cytokines, do not support high levels of HIV replication, unlike monocytes.
Area of Science:
- Neuroscience
- Immunology
- Virology
Background:
- Parenchymal microglia are primary targets of Human Immunodeficiency Virus (HIV) infection within the central nervous system (CNS).
- Previous studies utilized in vitro microglia culture systems to investigate HIV tropism and replication.
- Distinct surface markers between perivascular and parenchymal microglia suggest varied roles in CNS infection.
Purpose of the Study:
- To investigate the influence of culture conditions, specifically serum and cytokines, on HIV replication in human adult parenchymal microglia.
- To compare a novel microglia culturing protocol with standard methods.
- To determine if ex vivo parenchymal microglia support HIV replication, similar to monocytes.
Main Methods:
- Human adult parenchymal microglia were cultured from temporal lobe tissue using standard serum/cytokine-supplemented media and a novel protocol.
- The novel protocol involved culturing microglia with a glial 'feeder' layer and without serum/cytokines.
- Surface marker expression (CD11c, CD45, CD68, CD14) and HIV replication levels were assessed under different culture conditions.
Main Results:
- Microglia cultured with standard media exhibited specific surface markers (CD11c+, CD45+, CD68+, CD14-).
- Microglia cultured using the novel protocol (with feeder cells, without serum/cytokines) maintained similar surface markers.
- Pure microglia cultured without serum/cytokines or feeder cells showed altered morphology and significantly reduced HIV replication compared to standard cultures.
- Ex vivo parenchymal microglia supported HIV replication, a capability not observed in monocytes.
Conclusions:
- Culture conditions significantly impact microglial morphology and their ability to support HIV replication.
- Pure parenchymal microglia require specific environmental cues (serum, cytokines, or feeder cells) for optimal HIV replication.
- Ex vivo parenchymal microglia are capable of supporting HIV replication, highlighting their potential role in CNS HIV pathogenesis.
