Related Experiment Video
Updated: Feb 7, 2026
Native Polyacrylamide Gel Electrophoresis Immunoblot Analysis of Endogenous IRF5 Dimerization
Published on: October 6, 2019
IRF5 Is a Key Regulator of Macrophage Response to Lipopolysaccharide in Newborns
Anina Schneider1,2, Manuela Weier1,2, Jacobus Herderschee2
1Clinic of Neonatology, Department of Woman-Mother-Child, Lausanne University Hospital, Lausanne, Switzerland.
Insights
Newborn monocytes can become M1 or M2 macrophages, but produce less TNF due to lower IRF5 levels. Restoring IRF5 enhances newborn macrophage TNF production, revealing a distinct neonatal immune response.
Area of Science:
- Immunology
- Neonatal Immunity
- Cellular Biology
Background:
- Neonatal infections pose significant risks due to immature immune systems.
- Monocytes differentiate into M1 (pro-inflammatory) or M2 (anti-inflammatory) macrophages, crucial for immune regulation.
- Understanding neonatal immune cell function is vital for combating infant infections.
Purpose of the Study:
- To compare monocyte differentiation and polarization into M1/M2 macrophages between newborns and adults.
- To investigate the molecular mechanisms underlying potential differences in neonatal macrophage function.
- To identify key regulators of neonatal macrophage responses.
Main Methods:
- Monocytes isolated from umbilical cord blood (newborns) and peripheral blood (adults).
- Induction of M1 and M2 macrophages using GM-CSF or M-CSF.
- Analysis of macrophage morphology, surface markers (e.g., CD163), cytokine production (e.g., TNF, IL-1β, IL-6), and transcription factor levels (e.g., IRF5, NF-κB).
- Functional assessment using TLR4 stimulation and adenoviral-mediated gene overexpression.
Main Results:
- Newborn and adult monocytes differentiated into M1/M2 macrophages with similar morphology and most markers.
- Newborn M1 macrophages showed significantly higher CD163 expression but produced lower levels of TNF upon TLR4 stimulation compared to adults.
- Reduced nuclear levels of IRF5, a key M1 polarization factor, were observed in newborn M1 macrophages; NF-κB and MAP kinase pathways were unaffected.
- Overexpression of IRF5 in newborn M1 macrophages restored lipopolysaccharide-induced TNF production.
Conclusions:
- Neonatal macrophages exhibit distinct functional properties, particularly in TNF production, compared to adult macrophages.
- Lower levels of the transcription factor IRF5 are a key factor contributing to the reduced TNF response in newborn M1 macrophages.
- IRF5 plays a critical role in regulating TNF production in neonatal macrophages, highlighting a specific target for immune modulation.
Abstract:
Infections are a leading cause of mortality and morbidity in newborns. The high susceptibility of newborns to infection has been associated with a limited capacity to mount protective immune responses. Monocytes and macrophages are involved in the initiation, amplification, and termination of immune responses. Depending on cues received from their environment, monocytes differentiate into M1 or M2 macrophages with proinflammatory or anti-inflammatory and tissue repair properties, respectively. The purpose of this study was to characterize differences in monocyte to macrophage differentiation and polarization between newborns and adults. Monocytes from umbilical cord blood of healthy term newborns and from peripheral blood of adult healthy subjects were exposed to GM-CSF or M-CSF to induce M1 or M2 macrophages. Newborn monocytes differentiated into M1 and M2 macrophages with similar morphology and expression of differentiation/polarization markers as adult monocytes, with the exception of CD163 that was expressed at sevenfold higher levels in newborn compared to adult M1 macrophages. Upon TLR4 stimulation, newborn M1 macrophages produced threefold to sixfold lower levels of TNF than adult macrophages, while production of IL-1-β, IL-6, IL-8, IL-10, and IL-23 was at similar levels as in adults. Nuclear levels of IRF5, a transcription factor involved in M1 polarization, were markedly reduced in newborns, whereas the NF-κB and MAP kinase pathways were not altered. In line with a functional role for IRF5, adenoviral-mediated IRF5 overexpression in newborn M1 macrophages restored lipopolysaccharide-induced TNF production. Altogether, these data highlight a distinct immune response of newborn macrophages and identify IRF5 as a key regulator of macrophage TNF response in newborns.
Related Concept Videos
01:31Regulation of the Unfolded Protein Response
02:35Key Elements for Plant Nutrition
01:19Formation of Lipopolysaccharides
01:19Key Techniques in Microbiology
02:23Master Transcription Regulators
02:58Regulated Protein Degradation
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...