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Cecal Ligation and Puncture-induced Sepsis as a Model To Study Autophagy in Mice
Published on: February 9, 2014
M1 Macrophages Increase Endothelial Permeability and Enhance p38 Phosphorylation via PPAR-γ/CXCL13-CXCR5 in Sepsis
1General Practice Department of Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Purpose:
Vascular endothelial hyperpermeability and barrier disruption are involved in the initiation and development of sepsis. M1 macrophages promote inflammation in sepsis by releasing pro-inflammatory cytokines and chemokines. This study was designed to investigate the functional relationships between M1 macrophages and human umbilical vein endothelial cells (HUVECs), as well as the underlying molecular mechanisms.
Methods:
HUVECs were co-cultured with THP-1-derived M1 macrophages pretreated with or without rosiglitazone (RSG), a peroxisome proliferator-activated receptor (PPAR)-γ agonist. C-X-C chemokine receptor type (CXCR)5 was knocked down by short hairpin RNA lentivirus. Cecal ligation and puncture were used to induce sepsis in a mouse model. Endothelial permeability was evaluated using transendothelial electrical resistance and fluorescein isothiocyanate (FITC)-dextran assays.
Results:
Chemokine ligand (CXCL)13 was upregulated in M1 macrophages than M0 macrophages, as well as in the culture medium. In HUVECs co-cultured with M1 macrophages, transendothelial electrical resistance decreased, FITC-dextran flux increased, p38 phosphorylation was strengthened, and the expression of tight junction proteins (zonula occludens protein-1, occludin, and claudin-4) decreased. CXCR5 RNA interference or RSG pretreatment partially reversed these effects. A luciferase reporter assay revealed that CXCL13 was a direct target of PPAR-γ. RSG treatment decreased serum levels of creatinine, blood urea nitrogen, CXCL13, tumor necrosis factor-α, and interleukin-6, downregulated CXCL13 in peritoneal macrophages, and enhanced the survival rate of sepsis mice.
Conclusion:
M1 macrophages induced endothelial hyperpermeability and promoted p38 phosphorylation in sepsis by inhibiting PPAR-γ to increase CXCL13 production. PPAR-γ/CXCL13-CXCR5 signaling could be a promising novel therapeutic target for sepsis.
Insights
M1 macrophages increase sepsis-induced endothelial barrier dysfunction by inhibiting PPAR-γ, leading to CXCL13 upregulation. Targeting the PPAR-γ/CXCL13-CXCR5 pathway offers a potential therapeutic strategy for sepsis.
Area of Science:
- Immunology
- Vascular Biology
- Molecular Medicine
Background:
- Sepsis involves vascular endothelial hyperpermeability and barrier disruption.
- M1 macrophages exacerbate sepsis inflammation via pro-inflammatory cytokines and chemokines.
Purpose of the Study:
- Investigate the functional link between M1 macrophages and human umbilical vein endothelial cells (HUVECs).
- Elucidate the molecular mechanisms driving M1 macrophage-induced endothelial dysfunction in sepsis.
Main Methods:
- Co-culture of HUVECs with M1 macrophages, with or without rosiglitazone (PPAR-γ agonist).
- CXCR5 knockdown using shRNA lentivirus.
- Sepsis induction via cecal ligation and puncture in mice.
- Assessment of endothelial permeability using TEER and FITC-dextran assays.
Main Results:
- M1 macrophages increased endothelial permeability and p38 phosphorylation while decreasing tight junction proteins in HUVECs.
- CXCL13 was upregulated in M1 macrophages and correlated with endothelial dysfunction.
- Rosiglitazone or CXCR5 knockdown partially reversed these detrimental effects.
- RSG treatment improved sepsis outcomes in mice, reducing inflammatory markers and improving survival.
Conclusions:
- M1 macrophages induce endothelial hyperpermeability in sepsis by inhibiting PPAR-γ, which increases CXCL13 production.
- The PPAR-γ/CXCL13-CXCR5 signaling pathway presents a potential therapeutic target for sepsis treatment.
