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Updated: Nov 8, 2025
Experimental Infection with Listeria monocytogenes as a Model for Studying Host Interferon-γ Responses
Published on: November 16, 2016
PDCD4-mediated downregulation of Listeria monocytogenes burden in macrophages
Xingju Zhang1,2, Jiale Zhang3, Fei Li4
1Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China.
Introduction:
Macrophages are effector cells of the innate immune system and defend against invading pathogens. Previous reports have shown that infection with Listeria monocytogenes upregulates miR-21a expression in macrophages.
Aim Of The Study:
We aimed to verify whether programmed cell death 4 (PDCD4) is involved in the high bacterial burden observed in macrophages during late-stage L. monocytogenes infections.
Material And Methods:
We examined the expression of miR-21a and its known target PDCD4 in macrophages after L. monocytogenes infection. The macrophages' uptake ability of L. monocytogenes was measured using FluoSpheres Carboxylate-modified microspheres. We depleted PDCD4 by transfecting macrophages with siPDCD4.
Results:
In macrophages, PDCD4 protein was downregulated 5 h, but not 2 h, after L. monocytogenes infection. Our results validated the hypothesis that PDCD4-depleted macrophages present a higher L. monocytogenes burden. Moreover, we found that the activation of c-Jun and STAT3 accompanied PDCD4 downregulation.
Conclusions:
Our results showed that PDCD4 mediated the suppression of L. monocytogenes infection in macrophages via c-Jun/STAT3 signalling activation.
Insights
Programmed cell death 4 (PDCD4) protein is downregulated in macrophages during Listeria monocytogenes infection. PDCD4 depletion increases bacterial burden, highlighting its role in controlling infection.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Macrophages are key innate immune cells defending against pathogens.
- Listeria monocytogenes infection is known to upregulate miR-21a in macrophages.
Purpose of the Study:
- To investigate the role of programmed cell death 4 (PDCD4) in macrophage response to Listeria monocytogenes.
- To determine if PDCD4 influences bacterial burden during infection.
Main Methods:
- Examined miR-21a and PDCD4 expression in infected macrophages.
- Assessed macrophage bacterial uptake using microspheres.
- Depleted PDCD4 using siPDCD4 transfection.
Main Results:
- PDCD4 protein was downregulated at 5 hours post-infection with Listeria monocytogenes.
- PDCD4-depleted macrophages exhibited a higher bacterial burden.
- PDCD4 downregulation correlated with c-Jun and STAT3 activation.
Conclusions:
- PDCD4 plays a crucial role in suppressing Listeria monocytogenes infection in macrophages.
- The PDCD4-mediated suppression involves the activation of c-Jun/STAT3 signaling pathways.
