Background: Overproduction of proinflammatory cytokines from activated microglia has been implicated as an important contributor to pathophysiology progression in both acute and chronic neurodegenerative diseases. Therefore, it is critical to elucidate intracellular signaling pathways that are significant contributors to cytokine overproduction in microglia exposed to specific stressors, especially pathways amenable to drug interventions. The serine/threonine protein kinase p38α MAPK is a key enzyme in the parallel and convergent intracellular signaling pathways involved in stressor-induced production of IL-1β and TNFα in peripheral tissues, and is a drug development target for peripheral inflammatory diseases. However, much less is known about the quantitative importance of microglial p38α MAPK in stressor-induced cytokine overproduction, or the potential of microglial p38α MAPK to be a druggable target for CNS disorders. Therefore, we examined the contribution of microglial p38αMAPK to cytokine up-regulation, with a focus on the potential to suppress the cytokine increase by inhibition of the kinase with pharmacological or genetic approaches.Methods: The microglial cytokine response to TLR ligands 2/3/4/7/8/9 or to Aβ1-42 was tested in the presence of a CNS-penetrant p38α MAPK inhibitor, MW01-2-069A-SRM. Primary microglia from mice genetically deficient in p38α MAPK were used to further establish a linkage between microglia p38α MAPK and cytokine overproduction. The in vivo significance was determined by p38α MAPK inhibitor treatment in a LPS-induced model of acute neuroinflammation.Results: Increased IL-1β and TNFα production by the BV-2 microglial cell line and by primary microglia cultures was inhibited in a concentration-dependent manner by the p38α MAPK-targeted inhibitor. Cellular target engagement was demonstrated by the accompanying decrease in the phosphorylation state of two p38α MAPK protein substrates, MK2 and MSK1. Consistent with the pharmacological findings, microglia from p38α-deficient mice showed a diminished cytokine response to LPS. Further, oral administration of the inhibitor blocked the increase of IL-1β in the cerebral cortex of mice stressed by intraperitoneal injection of LPS.Conclusion: The p38α MAPK pathway is an important contributor to the increased microglial production of proinflammatory cytokines induced by diverse stressors. The results also indicate the feasibility of targeting p38α MAPK to modulate CNS proinflammatory cytokine overproduction.
|Journal||Journal of Neuroinflammation|
|State||Published - Jul 6 2011|
Bibliographical noteFunding Information:
DMW and LVE are principal investigators on project funding from the NIH and non-profit disease foundations with development of CNS new molecular entities as the long-term goal. Patents and patent applications covering novel compounds, including the one described here, have been filed by Northwestern University’s technology transfer office and licensed to industry.
This research was supported in part by funding from the Alzheimer’s Drug Discovery Foundation (DMW), Alzheimer’s Association Zenith grant ZEN-09-134506 (LVE), and NIH grants R01 AG031311 (DMW), R01 NS056051 (DMW), and R01 NS064247 (LVE). ADB is supported by NIH fellowship F32 AG037280. We are grateful to Dr. Huiping Jiang at Boehringer Ingelheim Pharmaceuticals, Inc. and Dr. Jiahuai Han at The Scripps Research Institute for the kind gifts of the knockout mice.
- Amyloid beta-peptides
- Drug discovery
- Knockout mice
- P38alpha mitogen-activated protein kinase
- Toll-like receptors
ASJC Scopus subject areas
- Neuroscience (all)
- Cellular and Molecular Neuroscience