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Updated: Oct 17, 2025
A Microphysiological System to Study Leukocyte-Endothelial Cell Interaction during Inflammation
Published on: December 9, 2021
Polymorphonuclear neutrophils promote endothelial apoptosis by enhancing adhesion upon stimulation by intermittent
1Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital, 154 Anshan Road, Heping District, Tianjin, 300052, China.
Purpose:
This study explored the interactive effects between polymorphonuclear neutrophils (PMNs) and vascular endothelial cells under intermittent hypoxia (IH) and investigated the mechanisms underlying these effects.
Methods:
Endothelial cells were co-cultured with PMNs isolated from rats exposed to normoxia or IH. The PMN apoptotic rate was determined using flow cytometry. Expression of apoptosis-related proteins in the endothelial cells were evaluated using Western blotting, and the levels of intercellular adhesion molecules in the co-culture supernatants were measured using enzyme-linked immunosorbent assay.
Results:
The PMN apoptotic rate in the IH-exposed rat group was significantly lower than that of the normoxia control group. There was a positive relationship between the PMN apoptotic rate and IH exposure time. In endothelial cells co-cultured with PMNs isolated from IH-exposed rats, a significant increase in the protein expression levels of Bax, Bcl-2, and caspase-3 and a significant decrease in the Bcl-2/Bax ratio were observed. Furthermore, the intercellular cell adhesion molecule-1(ICAM-1) and E-select element (E-S) levels were elevated significantly in the co-cultured supernatants of endothelial cells and PMNs from IH-exposed rats compared to that from controls. The above IH-induced alterations were partially restored by tempol pretreatment.
Conclusions:
The apoptotic rate was low in PMNs from IH-exposed rats, which consequently increased the apoptotic signals in endothelial cells in vitro. This may be associated with the increased levels of intercellular adhesion molecules. Further, tempol partially attenuates the PMN-mediated pro-apoptotic effects on endothelial cells under IH.
Insights
Intermittent hypoxia (IH) reduces polymorphonuclear neutrophil (PMN) apoptosis, increasing PMN-mediated damage to endothelial cells. Tempol treatment partially reverses these harmful effects, offering potential therapeutic insights.
Area of Science:
- Cardiovascular Biology
- Immunology
- Cell Biology
Background:
- Intermittent hypoxia (IH) is linked to cardiovascular complications.
- Polymorphonuclear neutrophils (PMNs) play a role in endothelial dysfunction.
- Understanding PMN-endothelial cell interactions under IH is crucial.
Purpose of the Study:
- To investigate the interactive effects between PMNs and vascular endothelial cells under IH.
- To elucidate the mechanisms driving these interactions.
- To assess the potential protective role of tempol.
Main Methods:
- Co-culture of endothelial cells with PMNs from normoxic or IH-exposed rats.
- Flow cytometry to assess PMN apoptosis.
- Western blotting for apoptosis-related proteins in endothelial cells.
- ELISA for intercellular adhesion molecules (ICAM-1, E-selectin).
Main Results:
- IH exposure significantly decreased PMN apoptosis.
- Endothelial cells co-cultured with IH-PMNs showed increased pro-apoptotic proteins (Bax, caspase-3) and decreased Bcl-2/Bax ratio.
- Elevated ICAM-1 and E-selectin levels were observed in IH-PMN co-cultures.
- Tempol pretreatment partially reversed IH-induced alterations.
Conclusions:
- Reduced PMN apoptosis under IH contributes to increased endothelial cell apoptosis.
- Elevated intercellular adhesion molecules may mediate PMN-endothelial cell interactions.
- Tempol demonstrates partial protective effects against PMN-mediated endothelial damage under IH.
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