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Updated: May 26, 2026
Pseudomonas aeruginosa Induced Lung Injury Model
Published on: October 29, 2014
Expression of IL-23, VEGF and TLR2/TLR4 on mononuclear cells after exposure to Pseudomonas aeruginosa
R Paolillo1, C Romano Carratelli, S Sorrentino
1Department of Experimental Medicine, Second University of Naples, Naples, Italy.
Abstract:
Pseudomonas aeruginosa is a Gram-negative, aerobic bacillus causing infections of the respiratory and other organ systems in susceptible hosts. Although it does not cause pulmonary infections in immunocompetent individuals, P. aeruginosa causes chronic lung infection in individuals with cystic fibrosis and nosocomial pneumonia resulting in significant morbidity and mortality. Exogenous administration of an important P. aeruginosa virulence factor, lipase, present in P. aeruginosa culture supernatant, induces potent mononuclear cell activation leading to the production of numerous proinflammatory cytokines. In particular, P. aeruginosa culture supernatant stimulated increased proliferation of THP-1 cells and monocytes (MN). The addition of culture supernatant to THP-1 cells and MN also induced Interleukin (IL)-23 and vascular endothelial growth factor (VEGF) release in a time-dependent manner. To investigate whether any compounds present in the supernatant lipase contributed to releasing IL-23 and VEGF, the culture supernatant from P. aeruginosa containing lipase was treated with hexadecylsulfonylfluoride (AMSF). The AMSF-treated culture supernatant (CS) did not show any induction on the IL-23 and VEGF release compared to the cells treated with CS without AMSF. We also showed that Toll-like receptors (TLR)2/TLR4 are expressed in THP-1 cells and MN treated with P. aeruginosa CS in a time-dependent fashion. Flow cytometry analysis revealed a higher TLR4 and a lower TLR2 expression at 48 and 72 h of treatment. The treatment of cells with TLR4 neutralizing antibody, and to a lesser extent with TLR2 neutralizing antibody, resulted in a decrease in P. aeruginosa CS-induced IL-23 and VEGF production.
Insights
Pseudomonas aeruginosa lipase in culture supernatant activates immune cells, increasing IL-23 and VEGF. This response is mediated by Toll-like receptors (TLR)4 and TLR2, highlighting a key mechanism in P. aeruginosa infections.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Pseudomonas aeruginosa is a Gram-negative bacterium causing severe infections, particularly in vulnerable individuals like those with cystic fibrosis.
- P. aeruginosa virulence factors, such as lipase, can trigger potent immune responses.
- Understanding the molecular mechanisms of P. aeruginosa-induced inflammation is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the role of P. aeruginosa lipase in immune cell activation and cytokine production.
- To determine the involvement of Toll-like receptors (TLR) in the inflammatory response induced by P. aeruginosa culture supernatant.
- To elucidate the signaling pathways leading to Interleukin (IL)-23 and vascular endothelial growth factor (VEGF) release.
Main Methods:
- THP-1 cells and primary monocytes were treated with P. aeruginosa culture supernatant.
- Lipase activity was inhibited using hexadecylsulfonylfluoride (AMSF).
- Flow cytometry was used to analyze TLR2 and TLR4 expression, and neutralizing antibodies were employed to block TLR signaling.
Main Results:
- P. aeruginosa culture supernatant induced proliferation of THP-1 cells and monocytes, along with the release of IL-23 and VEGF.
- Inhibition of lipase activity with AMSF abolished the induction of IL-23 and VEGF release.
- P. aeruginosa culture supernatant upregulated TLR4 and downregulated TLR2 expression in a time-dependent manner.
- Blocking TLR4, and to a lesser extent TLR2, with neutralizing antibodies significantly reduced IL-23 and VEGF production.
Conclusions:
- P. aeruginosa lipase is a key factor in activating mononuclear cells and driving the release of IL-23 and VEGF.
- The inflammatory response is mediated through TLR4 and TLR2 signaling pathways.
- These findings provide insights into the pathogenesis of P. aeruginosa infections and suggest potential therapeutic targets.
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