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Updated: Jul 15, 2026
09:18
Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death
Published on: December 27, 2016
Serotonin activates human monocytes and prevents apoptosis
Fujiko Soga1, Norito Katoh, Tomoko Inoue
1Department of Dermatology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, Japan.
The Journal of Investigative Dermatology
|April 13, 2007
Summary
Serotonin (5-hydroxytryptamine, 5-HT) activates monocytes and inhibits their apoptosis, contributing to chronic inflammation in atopic dermatitis (AD). Increased 5-HT levels in AD patients correlate with disease severity.
Area of Science:
- Immunology
- Dermatology
- Cell Biology
Background:
- Monocytes are key leukocytes in chronic atopic dermatitis (AD), interacting with activated platelets.
- Platelet mediators, like serotonin (5-hydroxytryptamine, 5-HT), are implicated in cutaneous allergic inflammation, but their precise role is unclear.
Purpose of the Study:
- To investigate the effects of 5-HT on human monocyte function and apoptosis.
- To explore the role of 5-HT in the pathogenesis of atopic dermatitis.
Main Methods:
- Human monocytes were treated with 5-HT, and their expression of costimulatory molecules and cytokine production was assessed.
- Monocyte apoptosis was measured in normal individuals and AD patients, with analysis of apoptosis-related proteins and receptor involvement.
- Plasma 5-HT levels and SCORAD index were correlated in AD patients.
Main Results:
- 5-HT upregulated costimulatory molecules, enhanced cytokine production, and T-cell stimulation in monocytes.
- 5-HT dose-dependently inhibited monocyte apoptosis by upregulating Bcl-2 and Mcl-1, and inhibiting caspase-3 activation.
- Elevated plasma 5-HT levels in AD patients correlated with SCORAD index, and 5-HT inhibited monocyte apoptosis in these patients.
- 5-HT effects were mediated by 5-HT1/5-HT7 receptors, involving ERK1/2 phosphorylation and NF-kappaB activation.
Conclusions:
- 5-HT activates human monocytes and suppresses their apoptosis, promoting their survival in tissues.
- These findings suggest that 5-HT contributes to the chronic inflammatory processes observed in atopic dermatitis.
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01:17Phagocytosis of Apoptotic Cells
Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or immature dendritic cells. Non-professional phagocytes such as epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
01:30Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
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