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Updated: Apr 21, 2026
Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation
Published on: April 29, 2015
Critical role of p38 MAPK in IL-4-induced alternative activation of peritoneal macrophages
Lidia Jiménez-Garcia1, Sandra Herránz, Alfonso Luque
1Unidad de Terapias Farmacológicas. Área de Genética Humana. Instituto de Investigación de Enfermedades Raras (IIER), Instituto de Salud Carlos III, Madrid, Spain.
Abstract:
Alternative activation of macrophages plays an important role in a range of physiological and pathological processes. This alternative phenotype, also known as M2 macrophages, is induced by type 2 cytokines such as IL-4. The binding of IL-4 to its receptor leads to activation of two major signaling pathways: STAT-6 and PI3K. However, recent studies have described that p38 MAPK might play a role in IL-4-dependent signaling in some cells, although its role in macrophages is still controversial. In this study, we investigated whether p38 MAPK plays a role in the polarization of macrophages in mice. Our results reveal that IL-4 induces phosphorylation of p38 MAPK in thioglycollate-elicited murine peritoneal macrophages, in addition to STAT-6 and PI3K activation. Furthermore, p38 MAPK inactivation, by gene silencing or pharmacological inhibition, suppressed IL-4-induced typical M2 markers, indicating the involvement of p38 MAPK in the signaling of IL-4 leading to M2-macrophage polarization. Moreover, p38 MAPK inhibition blocked phosphorylation of STAT-6 and Akt, suggesting that p38 MAPK is upstream of these signaling pathways. Finally, we show that in an in vivo model of chitin-induced M2 polarization, p38 MAPK inhibition also diminished activation of M2 markers. Taken together, our data establish a new role for p38 MAPK during IL-4-induced alternative activation of macrophages.
Insights
p38 MAPK is crucial for M2 macrophage polarization, a key immune response. This study shows p38 MAPK signaling is essential for IL-4-induced M2 macrophage activation, impacting immune regulation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Signaling
Background:
- Alternative macrophage activation (M2 phenotype) is vital in physiological and pathological processes.
- Interleukin-4 (IL-4) is a key inducer of M2 macrophages, primarily activating STAT-6 and PI3K pathways.
- The role of p38 MAPK in IL-4-dependent macrophage signaling remains controversial.
Purpose of the Study:
- To investigate the role of p38 MAPK in IL-4-induced M2 macrophage polarization in mice.
- To determine if p38 MAPK is upstream of STAT-6 and PI3K signaling in this context.
Main Methods:
- Utilized thioglycollate-elicited murine peritoneal macrophages.
- Employed gene silencing and pharmacological inhibition of p38 MAPK.
- Assessed STAT-6, PI3K (Akt), and M2 marker activation.
- Investigated an in vivo model of chitin-induced M2 polarization.
Main Results:
- IL-4 induced p38 MAPK phosphorylation alongside STAT-6 and PI3K activation in macrophages.
- Inhibition of p38 MAPK suppressed IL-4-induced M2 markers.
- p38 MAPK inhibition blocked STAT-6 and Akt phosphorylation, indicating it acts upstream.
- In vivo p38 MAPK inhibition reduced M2 marker activation during chitin-induced polarization.
Conclusions:
- p38 MAPK plays a significant role in IL-4-mediated M2 macrophage polarization.
- p38 MAPK acts upstream of STAT-6 and PI3K/Akt signaling pathways in this process.
- These findings establish a novel role for p38 MAPK in alternative macrophage activation.
