PGE2 induced in and released by dying cells functions as an inhibitory DAMP

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• Cellular components released during cell death, known as damage-associated molecular patterns (DAMPs), typically initiate protective inflammatory responses.
• However, dysregulated DAMP release can contribute to disease pathogenesis, and the regulatory mechanisms remain incompletely understood.

Purpose of the Study:

• To identify novel DAMPs that regulate immune responses.
• To elucidate the role of prostaglandin E2 (PGE2) as a DAMP.

Main Methods:

• Investigated PGE2 production under cell death conditions.
• Analyzed the transcriptional regulation of cyclooxygenase 2 (COX2) gene.
• Assessed the impact of cell-released PGE2 on inflammatory gene expression.
• Utilized in vivo models of acetaminophen-induced liver injury and tumor growth.

Main Results:

• Prostaglandin E2 (PGE2) was identified as a DAMP that negatively regulates immune responses.
• PGE2 production is increased under cell death conditions via transcriptional induction of COX2.
• Cell-released PGE2 suppresses inflammatory gene expression, limiting immunostimulatory activities.
• Inhibition of PGE2 synthesis potentiates inflammation induced by dying cells.
• PGE2 demonstrated a protective role in liver injury and a pathogenic role in tumor growth.

Conclusions:

• Prostaglandin E2 (PGE2) functions as an inhibitory DAMP, contrasting with traditionally recognized activating DAMPs.
• This discovery provides a new perspective on lipid mediators in immunity and inflammation.
• Findings have potential translational implications for developing therapies for inflammatory diseases.