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Mechanism of Neutrophil p90RSK-Nrf2 Signaling Pathway in Atherosclerosis

Jiawen Li¹, Lei Wang¹, Xiao Liang²

¹Department of Cardiology, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.

Balkan Medical Journal

|July 7, 2025

Abstract

Background:

MRP8/14, a calcium-binding protein of the S100 family, is predominantly expressed in myeloid cells and exhibits proinflammatory and prothrombotic properties. Platelet-neutrophil interactions can trigger MRP8/14 release, but their role in atherosclerosis (AS) remains unclear.

Aims:

To investigate the effect of MRP8/14 on AS progression and the underlying mechanisms involved, focusing on neutrophil activation and the toll-like receptor 4 (TLR4)-ERK1/2-p90RSK and NRF2-ARE pathways.

Study Design:

Ex vivo and animal study.

Methods:

Neutrophils isolated from mouse bone marrow were stimulated with P-selectin to induce MRP8/14 release, which was subsequently quantified using ELISA. Neutrophil extracellular traps (NET) formation was induced by phobolol 12-myristate 13-acetate, and Mrp8/14 expression was examined via fluorescence labeling. Cytokine release and CD11b expression were assessed using flow cytometry. An AS mouse model was established by administering a high-fat diet. Atherosclerotic plaque size was analyzed using Oil Red O staining. Proteins from the TLR4-ERK1/2-p90RSK and NRF2-ARE pathways were analyzed by Western blotting.

Results:

P-selectin induced MRP8/14 release, which was inhibited by P-selectin antagonists. NET formation also contributed to MRP8/14 secretion. hMRP8/14 treatment enhanced CD11b expression, neutrophil adhesion, and proinflammatory cytokine secretion. In AS mice, MRP8/14 secretion was linked to TLR4 upregulation, ERK1/2-p90RSK signaling activation, and NRF2-ARE pathway inhibition. Paquinimod, an MRP8/14 antagonist, mitigated neutrophil activation, inflammation, and arterial plaque formation.

Conclusion:

MRP8/14 secreted from neutrophils activates the ERK1/2-p90RSK pathway via TLR4 and suppresses the NRF2-ARE pathway, driving inflammation and promoting AS progression.

Insights

Myeloid-related protein 8/14 (MRP8/14) secreted by neutrophils promotes atherosclerosis (AS) by activating TLR4-ERK1/2-p90RSK and inhibiting NRF2-ARE pathways. MRP8/14 antagonists reduce inflammation and plaque formation in AS mice.

Area of Science:

Immunology
Molecular Biology
Cardiovascular Research

Background:

MRP8/14, a myeloid cell protein, has pro-inflammatory and pro-thrombotic effects.
Its role in atherosclerosis (AS) progression is not well understood.
Neutrophil activation and MRP8/14 release are linked to platelet interactions.

Purpose of the Study:

To investigate MRP8/14's impact on AS progression.
To elucidate the mechanisms involving neutrophil activation and specific molecular pathways (TLR4-ERK1/2-p90RSK, NRF2-ARE).

Main Methods:

Ex vivo neutrophil stimulation with P-selectin and phorbol ester to induce MRP8/14 release and NET formation.
Flow cytometry for cytokine release and CD11b expression.
AS mouse model with high-fat diet, analyzed for plaque size (Oil Red O) and protein pathways (Western blotting).

Main Results:

P-selectin stimulation induced MRP8/14 release, inhibited by antagonists.
MRP8/14 enhanced neutrophil activation, adhesion, and pro-inflammatory cytokine secretion.
In AS mice, MRP8/14 correlated with TLR4/ERK1/2-p90RSK activation and NRF2-ARE suppression.
Paquinimod (MRP8/14 antagonist) reduced AS progression and inflammation.

Conclusions:

MRP8/14 promotes AS by activating TLR4-ERK1/2-p90RSK and suppressing NRF2-ARE pathways.
Targeting MRP8/14 may offer a therapeutic strategy for atherosclerosis.

Read full analysis

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