Toggle Main Menu Toggle Search

Open Access padlockePrints

Plasma and rectal mucosal oxylipin levels during aspirin and eicosapentaenoic acid treatment in the seAFOod polyp prevention trial

Lookup NU author(s): Professor Colin Rees



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2023 The Author(s). Background: Aspirin and eicosapentaenoic acid (EPA) have colorectal polyp prevention activity, alone and in combination. This study measured levels of plasma and rectal mucosal oxylipins in participants of the seAFOod 2 × 2 factorial, randomised, placebo-controlled trial, who received aspirin 300 mg daily and EPA 2000 mg free fatty acid, alone and in combination, for 12 months. Methods: Resolvin (Rv) E1, 15-epi-lipoxin (LX) A4 and respective precursors 18-HEPE and 15-HETE (with chiral separation) were measured by ultra-high performance liquid chromatography-tandem mass spectrometry in plasma taken at baseline, 6 months and 12 months, as well as rectal mucosa obtained at trial exit colonoscopy at 12 months, in 401 trial participants. Results: Despite detection of S- and R- enantiomers of 18-HEPE and 15-HETE in ng/ml concentrations, RvE1 or 15‑epi-LXA4 were not detected above a limit of detection of 20 pg/ml in plasma or rectal mucosa, even in individuals randomised to both aspirin and EPA. We have confirmed in a large clinical trial cohort that prolonged (12 months) treatment with EPA is associated with increased plasma 18-HEPE concentrations (median [inter-quartile range] total 18-HEPE 0.51 [0.21–1.95] ng/ml at baseline versus 0.95 [0.46–4.06] ng/ml at 6 months [P<0.0001] in those randomised to EPA alone), which correlate strongly with respective rectal mucosal 18-HEPE levels (r = 0.82; P<0.001), but which do not predict polyp prevention efficacy by EPA or aspirin. Conclusion: Analysis of seAFOod trial plasma and rectal mucosal samples has not provided evidence of synthesis of the EPA-derived specialised pro-resolving mediator RvE1 or aspirin-trigged lipoxin 15‑epi-LXA4. We cannot rule out degradation of individual oxylipins during sample collection and storage but readily measurable precursor oxylipins argues against widespread degradation.

Publication metadata

Author(s): Fuller H, Race AD, Fenton H, Burke L, Downing A, Williams EA, Rees CJ, Brown LC, Loadman PM, Hull MA

Publication type: Article

Publication status: Published

Journal: Prostaglandins Leukotrienes and Essential Fatty Acids

Year: 2023

Volume: 192

Print publication date: 01/05/2023

Online publication date: 23/03/2023

Acceptance date: 21/03/2023

Date deposited: 13/04/2023

ISSN (print): 0952-3278

ISSN (electronic): 1532-2823

Publisher: Elsevier Ltd


DOI: 10.1016/j.plefa.2023.102570


Altmetrics provided by Altmetric


Funder referenceFunder name
Efficacy and Mechanism Evaluation (EME) Programme