Cultured human adult microglia from different donors display stable cytokine, chemokine and growth factor gene profiles but respond differently to a pro-inflammatory stimulus.

OBJECTIVES: Brain microglia are highly responsive cells in the central nervous system that exert key functions in host defense as well as in neuroprotection and regeneration. In this study the gene expression profiles for 268 cytokines, chemokines, growth factors and their receptors were examined in cultures of purified human adult microglia, using cDNA array profiling. METHODS: Microglia from 9 different donors were compared, also following challenge of such microglia with the pro-inflammatory cytokines TNF-alpha and IFN-gamma. RESULTS: A stable pattern was observed of genes abundantly expressed in the different cultures under standard conditions. Genes abundantly expressed in all microglia cultures include CCL2 (MCP-1), thymosin beta-10, migration-inhibitory factor-related protein 8 (MRP8), MRP14, corticotropin-releasing factor receptor 1 and endothelin 2. Abundant gene products novel to microglia were neuromodulin (GAP43) and Flt3 ligand. Yet, treatment with TNF-alpha and IFN-gamma led to widely different response profiles among the different cultures. CONCLUSION: These data show a surprising level of heterogeneity among human adult microglia cultures in their response to a pro-inflammatory stimulus despite the standardized methodology to examine this response.

Cytokine, chemokine and growth factor gene profiling of cultured human astrocytes after exposure to proinflammatory stimuli.

Astrocytes play key roles in CNS development, inflammation, and repair by producing a wide variety of cytokines, chemokines, and growth factors. Understanding the regulation of this network is important for a full understanding of astrocyte functioning. In this study, expression levels of 268 genes encoding cytokines, chemokines, growth factors, and their receptors were established in cultured human adult astrocytes using cDNA arrays. Also, changes in this gene profile were determined following stimulation with TNFalpha, IL-1beta, and IFNgamma. The data obtained reveal a highly reproducible pattern of gene expression not only between different astrocyte cultures from a single source, but also between astrocytes from different donors. They also identify several gene products not previously described for human astrocytes, including a.o. IL-17, CD70, CD147, and BIGH3. When stimulated with TNFalpha astrocytes respond with increased expression of several genes, notably including those encoding the chemokines CCL2 (MCP-1), CCL5 (RANTES), and CXCL8 (IL-8), growth factors including BMP-2A, BMP-3, neuromodulin (GAP43), BDNF, and G-CSF, and receptors such as the CRF receptor, the calcitonin receptor (CTR), and TKT. The response to IL-1beta involves largely the same range of genes, but responses were blunted in comparison to the TNFalpha response. Treatment with IFNgamma had no or only marginal effects on expression of any of the 268 genes analyzed. Astrocytes treated with a mixture of all three stimuli together displayed responses that are largely similar to those found in response to TNFalpha or IL-1beta alone, with only few additional synergistic effects.