Related Experiment Video
Updated: Jun 25, 2026
Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact
Published on: July 17, 2016
[Toll-like receptor 4 expression and cytokine secretion in microglial cells induced by IgG stimulation]
Rui Wu1, Ling Liu, Zheng-wu Peng
1College of Veterinary Medicine, Northwest A&F University, Yangling, China. wur2003@163.com
Insights
Immunoglobulin G (IgG) significantly increases toll-like receptor 4 (TLR4) expression and pro-inflammatory cytokine secretion in microglial cells. This suggests a broader role for TLR4 beyond pathogen recognition in the central nervous system.
Area of Science:
- Neuroimmunology
- Innate Immunity
- Cell Biology
Background:
- Microglia are the primary immune cells of the central nervous system.
- Toll-like receptor 4 (TLR4) is a key pattern recognition receptor involved in innate immunity.
- Immunoglobulin G (IgG) is a major antibody class with diverse functions.
Purpose of the Study:
- To investigate the impact of immunoglobulin G (IgG) on toll-like receptor 4 (TLR4) expression.
- To examine the effect of IgG on cytokine secretion in microglial cells.
- To explore the potential role of IgG in activating microglial inflammatory responses.
Main Methods:
- Primary rat microglial cells were cultured in vitro.
- Cells were stimulated with varying concentrations of rat IgG and lipopolysaccharide (LPS).
- TLR4 expression was assessed using immunofluorescence staining, and cytokine levels (TNF-alpha, IFN-gamma) were measured by ELISA.
Main Results:
- IgG stimulation dose-dependently increased TLR4 expression and TNF-alpha secretion.
- IFN-gamma was not detected in IgG-stimulated cells.
- LPS stimulation, used as a positive control, increased TLR4 expression and both TNF-alpha and IFN-gamma production.
Conclusions:
- Non-pathogenic immunoglobulin G (IgG) can induce toll-like receptor 4 (TLR4) expression in microglia.
- Congeneric IgG stimulation may trigger pro-inflammatory cytokine production, potentially through the MyD88-dependent pathway.
- TLR4's role in the central nervous system may extend beyond pathogen recognition to include responses to self-proteins like IgG.
Aim:
To investigate the effects of immunoglobulin G (IgG) on the expression of toll-like receptor 4 (TLR4) and secretion of cytokines in microglial cells in vitro.
Methods:
Cultured primary rat microglial cells were stimulated with different concentrations of rat IgG (2 mg/L, 20 mg/L, 200 mg/L) and lipopolysaccharide (LPS) 10 mg/L for 24 h, respectively. The TLR4 expression in the microglial cells was examined by immunofluorescence staining and tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) levels in the culture medium were assayed by ELISA.
Results:
IgG stimulation induced a significant TLR4 expression and TNF-alpha secretion in cultured microglial cells in a dose-dependent manner, while IFN-gamma was not detected in the same medium samples. As a positive control, LPS caused increases of TLR4 expression and both IFN-gamma and TNF-alpha production in the microglial cells.
Conclusion:
TLR4 expression could be induced in microglia in vitro by non-pathogenic protein, IgG from the same species. Therefore, congeneric IgG stimulation might lead to proinflammmatory cytokine production, probably via MyD88-dependent pathway. This finding suggests that TLR4 may play more roles than pathogen recognition of innate immune reactivity, at least in the central nervous system.
More Related Videos
10:40Immunofluorescence Staining Using IBA1 and TMEM119 for Microglial Density, Morphology and Peripheral Myeloid Cell Infiltration Analysis in Mouse Brain
Published on: October 27, 2019
06:12Engineering of Human Blood-Induced Microglia-like Cells for Reverse-Translational Brain Research
Published on: September 6, 2024
