1. The anti-inflammatory effect of LMWF5A and N-acetyl kynurenine on macrophages: Involvement of aryl hydrocarbon receptor in mechanism of action
- Author
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Raphael Bar-Or, David Bar-Or, Charles W. Mains, Allen Tanner, David L. Acuna, Leonard T. Rael, Kaysie L. Banton, Mark Lieser, and Michael Roshon
- Subjects
0301 basic medicine ,Agonist ,Lipopolysaccharide ,medicine.drug_class ,Biophysics ,NAK, N-acetyl kynurenine ,ESI+, electrospray positive ionization ,Inflammation ,Pharmacology ,Biochemistry ,lcsh:Biochemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine ,lcsh:QD415-436 ,Receptor ,lcsh:QH301-705.5 ,LCMS, liquid chromatography-mass spectrometry ,Aryl hydrocarbon receptor ,Kynurenine ,biology ,Chemistry ,NAT, N-acetyl tryptophan ,Macrophages ,Tryptophan ,Human serum albumin ,KYN, kynurenine ,LMWF5A, low molecular weight fraction of 5% albumin ,030104 developmental biology ,Mechanism of action ,lcsh:Biology (General) ,AhR, aryl hydrocarbon receptor ,biology.protein ,Phorbol ,medicine.symptom ,030217 neurology & neurosurgery ,HSA, human serum albumin ,Research Article - Abstract
After a traumatic insult, macrophages can become activated leading to general inflammation at the site of injury. Activated macrophages are partially regulated by the aryl hydrocarbon receptor (AhR) which when activated suppresses inflammation by limiting the secretion of pro-inflammatory cytokines and promoting the over expression of immuno-modulatory mediators. This study aims to determine whether the low molecular weight fraction of 5% human serum albumin (LMWF5A) and N-acetyl kynurenine (NAK), an N-acetyl tryptophan (NAT) breakdown product in LMWF5A, can regulate inflammation by inhibiting macrophage activation through the AhR since kynurenine is a known AhR agonist. Using LCMS, we demonstrate that NAT is non-enzymatically degraded during accelerated aging of LMWF5A with high heat accelerating degradation. More importantly, NAK is a major degradation product found in LMWF5A. THP-1 monocytes were differentiated into macrophages using phorbol 12-myristate 13-acetate (PMA) and pre-treated with 2-fold dilutions of LMWF5A or synthetic NAK with or without an AhR antagonist (CH223191) prior to overnight stimulation with lipopolysaccharide (LPS). Treatment with LMWF5A caused a 50–70% decrease in IL-6 release throughout the dilution series. A dose-response inhibition of IL-6 release was observed for NAK with maximal inhibition (50%) seen at the highest NAK concentration. Finally, an AhR antagonist partially blocked the anti-inflammatory effect of LMWF5A while completely blocking the effect of NAK. A similar inhibitory effect was observed for CXCL-10, but the AhR antagonist was not effective suggesting additional mechanisms for CXCL-10 release. These preliminary findings suggest that LMWF5A and NAK partially promote the suppression of activated macrophages via the AhR receptor. Therefore, LMWF5A, which contains NAK, is potentially a useful therapeutic in medical conditions where inflammation is prevalent such as trauma, sepsis, and wound healing., Highlights • LMWF5A contains degradation products of N-acetyl tryptophan (NAT). • A major degradation product of NAT in LMWF5A is N-acetyl kynurenine (NAK). • LMWF5A and NAK decrease IL-6 and CXCL-10 release from activated macrophages. • AhR is partially involved in the mechanism of action for LMWF5A and NAK. • The anti-inflammatory properties of LMWF5A are also AhR-independent.
- Published
- 2018