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Lipoxin formation in human nasal polyps and bronchial tissue
1Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
FEBS Letters
|October 15, 1990
Summary
Human nasal polyps and bronchial tissues produce lipoxins, potent anti-inflammatory mediators. Nasal polyps showed a higher capacity for lipoxin and 15-hydroxyeicosatetraenoic acid production, suggesting epithelial 15-lipoxygenase involvement in airway inflammation.
Area of Science:
- Biochemistry
- Immunology
- Respiratory Medicine
Background:
- Lipoxins are specialized pro-resolving mediators involved in inflammation resolution.
- Eicosanoids, including lipoxins, play crucial roles in respiratory diseases like asthma and rhinosinusitis.
- The specific pathways of lipoxin synthesis in human airway tissues remain incompletely understood.
Purpose of the Study:
- To investigate the capacity of human nasal polyps and bronchial tissues to produce lipoxins.
- To identify the specific lipoxins and related metabolites generated by these tissues.
- To explore the role of epithelial 15-lipoxygenase in lipoxin biosynthesis within the human airways.
Main Methods:
- Incubation of human nasal polyp and bronchial tissues with exogenous leukotriene A4.
- Incubation of tissues with arachidonic acid and ionophore A23187.
- Co-incubation of nasal polyps with polymorphonuclear granulocytes.
- Analysis of lipoxin and eicosanoid production using sensitive biochemical assays.
Main Results:
- Human nasal polyps and bronchial tissues produced lipoxin A4 and its isomers when incubated with leukotriene A4.
- These tissues also generated 15-hydroxyeicosatetraenoic acid from arachidonic acid.
- Nasal polyps exhibited a 3-5-fold higher capacity for lipoxin and 15-hydroxyeicosatetraenoic acid production compared to bronchial tissues.
- Lipoxin formation, including lipoxin A4 and B4, was observed upon co-incubation of nasal polyps with polymorphonuclear granulocytes.
- Neither tissue produced detectable lipoxins or leukotrienes when incubated with ionophore A23187 and arachidonic acid alone.
Conclusions:
- Human airway tissues, particularly nasal polyps, possess the enzymatic machinery for lipoxin synthesis.
- The results strongly suggest the involvement of an epithelial 15-lipoxygenase in the formation of lipoxins in human airways.
- These findings contribute to understanding the local inflammatory and pro-resolving mechanisms in respiratory tissues.