Human endothelial cells are activated by interferon‐γ plus tumour necrosis factor‐α to kill intracellular Pseudomonas aeruginosa

Abstract

Proinflammatory cytokines have been shown to activate endothelial cells. To investigate the effect of cytokines on the interaction of human umbilical vein endothelial cells (HUVEC) with Pseudomonas aeruginosa, cells were treated with interferon-gamma (IFN-gamma) plus tumour necrosis factor-alpha (TNF-alpha) for 24 hr and exposed to P. aeruginosa suspension for 1 hr. Light microscopy showed that activated cells internalized significantly more bacteria than control cells. To ascertain the effect of cytokines on the microbicidal activity of HUVEC, the concentrations of viable intracellular (IC) bacteria in control and activated cells were determined, at 1 and 5 hr postinfection, by the gentamicin exclusion assay. In control cells, no significant decrease in the concentration of bacteria was detected 5 hr postinfection. In contrast, in activated cells the concentration of viable bacteria at 5 hr was significantly lower. Concentrations of superoxide and hydrogen peroxide detected in supernatants of activated cells were significantly higher than in control cell supernatants. HUVEC anti-P. aeruginosa activity was insensitive to the antioxidants superoxide dismutase, dimethylthiourea and allopurinol as well as to the L-arginine analogues aminoguanidine and NG-monomethyl-L-arginine (L-NMMA), but was significantly inhibited by catalase. Our results indicate that HUVEC can be activated by IFN-gamma plus TNF-alpha to kill IC P. aeruginosa and suggest a role for reactive oxygen radicals, notably hydrogen peroxide, in HUVEC antibacterial activity.

Pretreatment of Pseudomonas aeruginosa with a sub-MIC of imipenem enhances bactericidal activity of neutrophils

“…2 (2) A significant increase in the generation of ORI was observed only in neutrophils which phagocytized imipenem-treated bacteria. Taken together with previous observations that the activation and enhanced generation of ORI play an important role in antimicrobial activity against P. aeruginosa, 20,21 we can speculate that increased ORI production may only be involved in the enhancement of PALE by pretreatment with imipenem at sub-MIC against P. aeruginosa. (3) The cytotoxicity of PAO-1 against neutrophils was not significantly suppressed by pretreatment with/without imipenem or ceftazidime.…”

Elimination of Pseudomonas aeruginosa through Efferocytosis upon Binding to Apoptotic Cells

“…Some of them have found that P . aeruginosa is unable to survive intracellularly long past 24 h, inside endothelial [16] and epithelial cells [17, 18]. On the other hand, García Medina et al suggested that airway epithelial cells develop pod-like clusters of intracellular P .…”

Real-time monitoring of cell mechanical changes induced by endothelial cell activation and their subsequent binding with leukemic cell lines

“…(Oshima et al 2001; Pezeshkian et al 2013; Zhang et al 2010) It has been shown that various factors (e.g. TNF-α, leukemic cells) can induce EC activation(De Assis et al 2000; Stucki et al 2001; Woodfin et al 2009) resulting in altered cell morphology as well as increased expression of various cytokines and cell adhesion molecules (CAMs) such as E-selectin, ICAM and VCAM as shown in scheme 1. (Carlos et al 1990; Osborn et al 1989; Shi et al 2004) Many of these molecules serve as biomarkers for EC activation,(Zhang et al 2010) with the kinetics of expression directly correlating to the extent of EC activation.…”