Related Experiment Videos
[Human monocytes show chemotaxis in response to cholesteatoma debris]
1Department of Otolaryngology, National Medical Center, Tokyo.
Abstract:
Using a microchamber technique, we tested cholesteatoma debris and certain of its constituents for effects on the migration of human peripheral blood monocytes and polymorphonuclear leukocytes. Cholesteatoma debris induced significant migration of monocytes. When the individual constituents of cholesteatoma debris, i.e., alpha-keratin, cholesterol, lauric acid and lipopolysaccharides, were tested for monocyte chemotaxis, only alpha-keratin induced significant monocyte migration. alpha-keratin extracted from the cholesteatoma debris with 8 M urea also induced migration of monocytes with a bell-shaped dose-response curve, which is frequently encountered with chemoattractants. Therefore, cholesteatoma debris and one of its components, alpha-keratin, are potent chemoattractants for human monocytes. On the other hand, cholesteatoma debris showed no significant chemotactic effect on polymorphonuclear leukocytes. Based on the present and our previous results, cholesteatoma debris acts on monocytes/macrophages as a strong chemotactant, a potent activating (priming) factor, and an inducer of production of tumor necrosis factor, which is a bone-resorbing cytokine. Therefore, we concluded that macrophages induced by cholesteatoma debris may play an important role in the pathogenesis of bone resorption in cholesteatoma otitis.
Insights
Cholesteatoma debris and alpha-keratin strongly attract human monocytes, a key cell in inflammation. This suggests a role for these factors in cholesteatoma otitis and bone resorption.
Area of Science:
- Otology
- Immunology
- Biochemistry
Context:
- Cholesteatoma otitis is a destructive inflammatory condition.
- The role of cholesteatoma debris in immune cell recruitment is not fully understood.
Purpose:
- To investigate the effects of cholesteatoma debris and its components on human monocyte and polymorphonuclear leukocyte migration.
Summary:
- Cholesteatoma debris significantly induced monocyte migration, while polymorphonuclear leukocyte migration was unaffected.
- Alpha-keratin, a component of cholesteatoma debris, was identified as the primary chemoattractant for monocytes.
- Cholesteatoma debris also primes monocytes/macrophages, inducing tumor necrosis factor production, a bone-resorbing cytokine.
Impact:
- Macrophages activated by cholesteatoma debris may contribute to the bone resorption seen in cholesteatoma otitis.
- Identifies alpha-keratin as a key mediator in the inflammatory response to cholesteatoma.