Screening for Inhibitors of Microglia to Reduce Neuroinflammation.
ABSTRACT Background: Despite the significant role microglia play in the pathology of multiple sclerosis (MS), medicationsthat act within the central nervous system (CNS) to inhibit microglia have not yet been identified as treatment options. Objective: We screened 1040 compounds with the aim of identifying inhibitors of microglia to reduce neuroinflammation. Methods: The NINDs collection of 1040 compounds, where most are therapeutic medications, was tested at 10 μM final concentration on lipopolysaccharide (LPS)-activated human microglia. An ELISA was run on the media to measure the level of TNF-α as an indicator of microglia activity. For compounds that reduce LPS-activated TNF-α levels by over 50%, considered as a potential inhibitor of interest, toxicity tests were conducted to exclude non-specific cytotoxicity. Promising compounds were subjected to further analyses, including toxicity to other CNS cell types, and multiplex assays. Results: Of 1040 compounds tested, 123reduced TNF-α levels of LPS-activated microglia by over 50%. However, most of these were cytotoxic to microglia at the concentration tested while 54were assessed to be non-toxic. Of the latter, spironolactone was selected for further analyses. Spironolactone reduced TNF-α levels of activated microglia by 50-60% at 10 μM, and this concentration did not kill microglia, neurons or astrocytes. In multiplex assays, spironolactone reduced several molecules in activated microglia. Finally, during the screening, we identified 9 compounds that elevated further the TNF-α levels in LPS-activated microglia. Conclusion: Many of the non-toxic compounds identified in this screen as inhibitors of microglia, including spironolactone,may be explored as viable therapeutic options in MS.
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ABSTRACT: Brain tumor initiating cells (BTICs) contribute to the genesis and recurrence of gliomas. We examined whether the microglia and macrophages that are abundant in gliomas alter BTIC growth. We found that microglia derived from non-glioma human subjects markedly mitigated the sphere-forming capacity of glioma patient-derived BTICs in culture by inducing the expression of genes that control cell cycle arrest and differentiation. This sphere-reducing effect was mimicked by macrophages, but not by neurons or astrocytes. Using a drug screen, we validated amphotericin B (AmpB) as an activator of monocytoid cells and found that AmpB enhanced the microglial reduction of BTIC spheres. In mice harboring intracranial mouse or patient-derived BTICs, daily systemic treatment with non-toxic doses of AmpB substantially prolonged life. Notably, microglia and monocytes cultured from glioma patients were inefficient at reducing the sphere-forming capacity of autologous BTICs, but this was rectified by AmpB. These results provide new insights into the treatment of gliomas.Nature Neuroscience 12/2013; · 15.25 Impact Factor