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Melatonin and its relation to the immune system and inflammation
R J Reiter1, J R Calvo, M Karbownik
1Department of Cellular and Structural Biology, Mail Code 7762, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA. reiter@uthscsa.edu
Annals of the New York Academy of Sciences
|March 28, 2001
Summary
Melatonin, an anti-inflammatory agent, reduces tissue damage by scavenging free radicals and inhibiting inflammatory pathways. Its non-pineal origins and broad protective actions are highlighted.
Area of Science:
- Endocrinology
- Immunology
- Cell Biology
Background:
- Melatonin (N-acetyl-5-methoxytryptamine) was initially believed to be solely produced by the pineal gland.
- Subsequent research identified melatonin synthesis in other organs, including the retinas, with high concentrations found in bone marrow and bile.
- The precise origin of melatonin in these non-pineal sites remains under investigation, suggesting multifaceted synthesis pathways.
Purpose of the Study:
- To elucidate the anti-inflammatory mechanisms of melatonin.
- To highlight melatonin's role in mitigating tissue destruction during inflammatory processes.
- To explore the diverse actions of melatonin beyond its traditional endocrine functions.
Main Methods:
- Review of existing literature on melatonin's synthesis and biological actions.
- Analysis of melatonin's free radical scavenging capabilities, including hydroxyl radical (.OH), peroxynitrite anion (ONOO-), and hypochlorous acid (HOCl).
- Investigation of melatonin's impact on nuclear factor-kappa B (NF-kappa B) translocation and subsequent cytokine regulation, as well as its effects on adhesion molecule production.
Main Results:
- Melatonin demonstrates potent anti-inflammatory effects by directly scavenging toxic free radicals, thereby reducing macromolecular damage.
- Melatonin inhibits the translocation of nuclear factor-kappa B (NF-kappa B) to the nucleus, downregulating proinflammatory cytokines like interleukins and tumor necrosis factor-alpha.
- Evidence suggests melatonin inhibits adhesion molecule production, attenuating leukocyte migration and edema, thus reducing tissue damage.
Conclusions:
- Melatonin possesses significant anti-inflammatory properties, acting through multiple mechanisms to protect tissues from inflammatory damage.
- Its ability to scavenge free radicals and modulate key inflammatory signaling pathways underscores its therapeutic potential.
- The non-pineal synthesis and widespread distribution of melatonin suggest a broader physiological role in managing inflammation and tissue integrity.