Effects of Quorum Sensing Systems on Regulatory T Cells in Catheter-RelatedPseudomonas aeruginosaBiofilm Infection Rat Models

Abstract

Background. Quorum sensing (QS) systems play an important role in modulating biofilm formation. Recent studies have found that the QS molecules had complex effects on the host immune systems. In addition, regulatory T cells (Tregs), known as important negative regulators in the immune system, have been found upregulated in multiple chronic infections. Therefore, the QS systems were hypothesized to be involved in modulating Tregs in biofilm-associated infections. Object. To explore the effects of QS systems on Tregs in catheter-related Pseudomonas aeruginosa biofilm infection rat models. Method. Catheter-related Pseudomonas aeruginosa biofilm infection rat models were established; the bacterial clearance rates, total cell counts in bronchoalveolar lavage (BAL) fluid, pathological changes of lungs, and the levels of Foxp3, TGF-β1, and IL-10 in PAO1 strain group were examined and compared with the QS-mutant ΔlasRΔrhlR and ΔlasIΔrhlI groups. Results. In PAO1 group, the bacterial clearance rates were lower, total cell counts were higher, pathological changes were severer, and the levels of Foxp3, TGF-β1, and IL-10 were significantly higher compared with QS-mutant groups (p < 0.05). No significant difference was observed between the two QS-mutant groups (p > 0.05). Conclusion. QS systems can trigger host immune system, accompanied with the upregulation of Tregs.

Pseudomonas aeruginosa Lifestyle: A Paradigm for Adaptation, Survival, and Persistence

“…Although they play a critical role in promoting bacterial growth and survival, they can cause devastating injuries to the host tissues and impair the immune responses. QS deficient mutants cause considerably less tissue damage and pathological changes during infections due to a significant decrease in the virulence and cytotoxicity (Nelson et al, 2009 ; Feng et al, 2016 ).…”

Mechanisms and Targeted Therapies forPseudomonas aeruginosaLung Infection

“…P. aeruginosa pigment molecules, pyocyanin and 1-hydroxyphenazine, in association with the tryptophan catabolic product kynurenine, produced by both the bacterium and host, appear sufficient to activate AHR during infection (78,79,163). In a rat catheterrelated lung infection model examining P. aeruginosa QS mutants, the production of suppressive cytokines (IL-10, TGF-b) and the presence of T regulatory lymphocytes were higher in the animals infected with the wild-type bacteria than in animals challenged with the mutants (164), suggesting that QS molecules also affect the induction of certain T-cell subsets.…”

Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

“…In patients with cystic fibrosis, the growth of bacteria in biofilm determines aggravation of the disease. Recent studies have found that the QS molecules interact with eukaryotic cells and modulate also host immune response [ 9 ]. But, although the roles of the N -acylhomoserine lactones in the modulation of immune response have been well studied, the results obtained until now were contradictory, depending on the cell line, the concentration and the time of action [ 10 ].…”