Helicobacter pylori urease induces pro-inflammatory effects and differentiation of human endothelial cells: Cellular and molecular mechanism.
BACKGROUND
Helicobacter pylori urease (HPU) is a key virulence factor that enables bacteria to colonize and survive in the stomach. We early demonstrated that HPU, independent of its catalytic activity, induced inflammatory and angiogenic responses in vivo and directly activated human neutrophils to produce reactive oxygen species (ROS). We have investigated the effects of HPU on endothelial cells, focusing on the signaling mechanism involved.


METHODS
Monolayers of human microvascular endothelial cells (HMEC-1) were stimulated with HPU (up to 10 nmol/L): Paracellular permeability was accessed through dextran-FITC passage. NO and ROS production was evaluated using intracellular probes. Proteins or mRNA expressions were detected by Western blotting and fluorescence microscopy or qPCR assays, respectively.


RESULTS
Treatment with HPU enhanced paracellular permeability of HMEC-1, preceded by VE-cadherin phosphorylation and its dissociation from cell-cell junctions. This caused profound alterations in actin cytoskeleton dynamics and focal adhesion kinase (FAK) phosphorylation. HPU triggered ROS and nitric oxide (NO) production by endothelial cells. Increased intracellular ROS resulted in nuclear factor kappa B (NF-κB) activation and upregulated expression of cyclooxygenase-2 (COX-2), hemeoxygenase-1 (HO-1), interleukin-1β (IL-1β), and intercellular adhesion molecule-1 (ICAM-1). Higher ICAM-1 and E-selectin expression was associated with increased neutrophil adhesion on HPU-stimulated HMEC monolayers. The effects of HPU on endothelial cells were dependent on ROS production and lipoxygenase pathway activation, being inhibited by esculetin. Additionally, HPU improved vascular endothelial growth factor receptor 2 (VEGFR-2) expression.


CONCLUSION
The data suggest that the pro-inflammatory properties of HPU drive endothelial cell to a ROS-dependent program of differentiation that contributes to the progression of H pylori infection.
['de Jesus Souza|Mariele|M|', 'de Moraes|João Alfredo|JA|', 'Da Silva|Vany Nascimento|VN|', 'Helal-Neto|Edward|E|', 'Uberti|Augusto Frantz|AF|', 'Scopel-Guerra|Adriele|A|', 'Olivera-Severo|Deiber|D|', 'Carlini|Célia R|CR|', 'Barja-Fidalgo|Christina|C|https://orcid.org/0000-0002-1917-4401']
D002454:Cell Differentiation D042783:Endothelial Cells D016481:Helicobacter Infections D016480:Helicobacter pylori D006801:Humans D007249:Inflammation D010766:Phosphorylation D017382:Reactive Oxygen Species D015398:Signal Transduction D014510:Urease D037521:Virulence Factors
endothelial cells Helicobacter pylori urease (HPU) reactive oxygen species (ROS) inflammation