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Updated: Nov 5, 2025
Magnetic Isolation of Microglial Cells from Neonate Mouse for Primary Cell Cultures
Published on: July 25, 2022
Mouse primary microglia respond differently to LPS and poly(I:C) in vitro
Yingbo He1, Natalie Taylor2, Xiang Yao3
1Janssen Research & Development, LLC., Neuroimmunology Drug Discovery, 3210 Merryfield Row, San Diego, CA, 92121, USA. yhe50@its.jnj.com.
Abstract:
Microglia, CNS resident innate immune cells, respond strongly to activation of TLR3 and TLR4, which recognize viral dsRNA poly(I:C) and bacterial endotoxin LPS, respectively. However, few studies have thoroughly and parallelly compared functional phenotypes and downstream mechanisms between LPS- and poly(I:C)-exposed primary microglia. Here, we investigated the responses of mouse primary microglia upon LPS and poly(I:C) stimulation by detecting various phenotypes ranging from morphology, proliferation, secretion, chemotaxis, to phagocytosis. Furthermore, we explored their sequential gene expression and the downstream signal cascades. Interestingly, we found that the microglial activation pattern induced by LPS was distinguished from that induced by poly(I:C). Regarding microglial morphology, LPS caused an ameboid-like shape while poly(I:C) induced a bushy shape. Microglial proliferation was also facilitated by LPS but not by poly(I:C). In addition, LPS and poly(I:C) modulated microglial chemotaxis and phagocytosis differently. Furthermore, genome-wide analysis provided gene-level support to these functional differences, which may be associated with NF-κb and type I interferon pathways. Last, LPS- and poly(I:C)-activated microglia mediated neurotoxicity in a co-culture system. This study extends our understanding of TLR roles in microglia and provides insights into selecting proper inflammatory microglial models, which may facilitate identification of new targets for therapeutic application.
Insights
Lipopolysaccharide (LPS) and poly(I:C) differentially activate microglia, impacting their shape, proliferation, and function. Understanding these distinct responses is crucial for developing targeted neuroinflammatory therapies.
Area of Science:
- Neuroimmunology
- Innate Immunity
Background:
- Microglia are key innate immune cells in the central nervous system (CNS).
- Toll-like receptors (TLRs) 3 and 4 recognize viral dsRNA (poly(I:C)) and bacterial endotoxin (LPS), respectively, activating microglia.
- Limited comparative studies exist on LPS- vs. poly(I:C)-induced microglial activation phenotypes and mechanisms.
Purpose of the Study:
- To comprehensively compare the functional phenotypes and downstream molecular mechanisms of primary mouse microglia stimulated by LPS and poly(I:C).
- To elucidate the distinct signaling pathways and gene expression profiles triggered by these two TLR agonists.
- To assess the impact of LPS- and poly(I:C)-activated microglia on neurotoxicity.
Main Methods:
- Primary mouse microglia were stimulated with LPS and poly(I:C).
- Phenotypic analyses included morphology, proliferation, secretion, chemotaxis, and phagocytosis.
- Genome-wide gene expression analysis and exploration of downstream signaling cascades (e.g., NF-κB, type I interferon pathways) were performed.
- Neurotoxicity was evaluated in a co-culture system.
Main Results:
- LPS induced an ameboid microglial morphology and proliferation, while poly(I:C) induced a bushy morphology without significant proliferation.
- Differential modulation of microglial chemotaxis and phagocytosis was observed between LPS and poly(I:C) treatments.
- Genome-wide analysis revealed distinct gene expression patterns, linked to NF-κB and type I interferon pathways.
- Both LPS- and poly(I:C)-activated microglia exhibited neurotoxic effects in co-culture.
Conclusions:
- LPS and poly(I:C) elicit distinct microglial activation patterns and downstream molecular responses.
- These findings highlight the importance of selecting appropriate inflammatory microglial models for research.
- The study provides insights into potential therapeutic targets for neuroinflammatory conditions.
