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Effect of Pseudomonas aeruginosa on interleukin-8 release from human phagocytes
1Medizinische Mikrobiologie und Immunologie, AG Infektabwehrmechanismen Ruhr-Universität Bochum, Deutschland, Germany.
Abstract:
Pseudomonas aeruginosa infections are commonly observed in sepsis, burns, as well as cystic fibrosis (CF). Among the professional phagocytes neutrophils and monocytes are recruited by various chemotactic factors from the cellular environment. Although they provide the first line of host defense excessive neutrophil accumulation seems to be a major cause of pathogenesis during P. aeruginosa infection. Interleukin-8 (IL-8) represents one important chemoattractant for professional phagocytes. To evaluate IL-8 releasability by phagocytes in the context of P. aeruginosa infection and especially of CF, we stimulated human polymorphonuclear neutrophilic granulocytes (PMN) and peripheral blood mononuclear cells (PBMC) as a source for monocytes with clinical P. aeruginosa isolates, with mucoid P. aeruginosa strain (CF3M) and its nonmucoid revertant (CF3), and with purified P. aeruginosa mucoid exopolysaccharide (alginate). A significant increase in IL-8 release as compared to unstimulated cells was observed after an incubation time of 90 min for PMN and after 60 min for PBMC which increased (PMN: up to 60-fold; PBMC: up to 40-fold) over time (up to 4 h). In contrast of PBMC, when PMN were studied, intracellular IL-8 exceeded the IL-8 release in unstimulated as well as in stimulated cells by up to 10-fold. All clinical P. aeruginosa isolates, independent of the clinical source, induced IL-8 release from human PBMC and PMN in a dose- and time-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Pseudomonas aeruginosa infection triggers significant Interleukin-8 (IL-8) release from human neutrophils and monocytes. This study quanties IL-8 releasability, crucial for understanding host defense and pathogenesis in conditions like cystic fibrosis.
Area of Science:
- Infectious Diseases
- Immunology
- Microbiology
Background:
- Pseudomonas aeruginosa infections are prevalent in sepsis, burns, and cystic fibrosis (CF).
- Neutrophils and monocytes are key phagocytes recruited during infection.
- Excessive neutrophil accumulation contributes to pathogenesis in P. aeruginosa infections.
Purpose of the Study:
- To evaluate Interleukin-8 (IL-8) releasability by human phagocytes (neutrophils and monocytes) in response to P. aeruginosa.
- To investigate the role of mucoid P. aeruginosa strains and alginate in IL-8 induction.
Main Methods:
- Human polymorphonuclear neutrophilic granulocytes (PMN) and peripheral blood mononuclear cells (PBMC) were stimulated with clinical P. aeruginosa isolates, a mucoid strain (CF3M), its nonmucoid revertant (CF3), and purified alginate.
- IL-8 release was measured over time (up to 4 hours) and compared to unstimulated cells.
- Intracellular IL-8 levels in PMN were also assessed.
Main Results:
- Significant dose- and time-dependent increases in IL-8 release were observed in both PMN and PBMC upon stimulation with P. aeruginosa.
- PMN showed up to a 60-fold increase in IL-8 release, while PBMC showed up to a 40-fold increase.
- Intracellular IL-8 in PMN exceeded released IL-8 in both unstimulated and stimulated conditions.
Conclusions:
- Clinical isolates of P. aeruginosa effectively induce IL-8 release from human phagocytes.
- IL-8 induction is a key response to P. aeruginosa, with neutrophils retaining significant intracellular IL-8.
- Understanding this IL-8 response is critical for managing P. aeruginosa infections, particularly in CF patients.