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Published on: March 16, 2017
Nitric oxide regulates interactions of PMN with human brain microvessel endothelial cells
Donald Wong1, Rukmini Prameya, Katerina Dorovini-Zis
1Department of Psychiatry and The Brain Research Centre, Section of Neuropathology, Vancouver Hospital, The University of British Columbia, Vancouver, BC, Canada.
Abstract:
The hypothesis that the NO/cGMP pathway modulates PMN adhesion to human brain microvessel endothelial cells (HBMEC) was examined. Human PMN were incubated with resting or TNF-alpha-treated endothelial monolayers, and adhesion was quantified by light microscopy. TNF-alpha upregulated PMN adhesion in a time-dependent manner. Treatment of HBMEC with the NO donors SNP and DETA NONOate for 4 or 24 h decreased PMN adhesion. This was completely reversed by the guanylyl cyclase inhibitor ODQ, while addition of a cGMP agonist (8-Br-cGMP) decreased PMN adhesion. NO donors did not affect the levels of E-selectin or ICAM-1 in HBMEC. However, pre-treatment of PMN with NO donors or 8-Br-cGMP decreased their adhesion to recombinant E-selectin and ICAM-1, suggesting an effect of NO on PMN. These findings indicate that NO modulates PMN-HBMEC interactions through cGMP and decreases the binding of PMN to the adhesion molecules E-selectin and ICAM-1.
Insights
Nitric oxide (NO) signaling, through cyclic guanosine monophosphate (cGMP), reduces the adhesion of neutrophils (PMN) to brain endothelial cells. This pathway impacts PMN binding to key adhesion molecules like E-selectin and ICAM-1.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Neutrophil (PMN) adhesion to endothelial cells is crucial in inflammatory responses.
- The role of the nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway in modulating PMN-endothelial cell interactions remains incompletely understood.
Purpose of the Study:
- To investigate whether the NO/cGMP pathway influences PMN adhesion to human brain microvessel endothelial cells (HBMEC).
- To determine the specific mechanisms by which NO affects PMN-endothelial cell interactions.
Main Methods:
- Human PMN and HBMEC were co-cultured, with HBMEC treated with TNF-alpha or NO donors (SNP, DETA NONOate).
- PMN adhesion was quantified using light microscopy.
- The effects of guanylyl cyclase inhibitor (ODQ) and cGMP agonist (8-Br-cGMP) were assessed.
- Expression of E-selectin and ICAM-1 on HBMEC was analyzed.
- PMN adhesion to recombinant E-selectin and ICAM-1 was evaluated.
Main Results:
- TNF-alpha significantly upregulated PMN adhesion to HBMEC.
- NO donors (SNP, DETA NONOate) decreased PMN adhesion to HBMEC, an effect reversed by ODQ.
- A cGMP agonist (8-Br-cGMP) also decreased PMN adhesion.
- NO donors did not alter E-selectin or ICAM-1 levels on HBMEC.
- Pre-treatment of PMN with NO donors or 8-Br-cGMP reduced their adhesion to E-selectin and ICAM-1.
Conclusions:
- The NO/cGMP pathway plays a significant role in modulating PMN adhesion to HBMEC.
- NO decreases PMN-HBMEC interactions by reducing PMN binding to E-selectin and ICAM-1, acting directly on the PMN.
- These findings highlight a novel mechanism for controlling neuroinflammation via the NO/cGMP pathway.
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