Celecoxib use and circulating oxylipins in a colon polyp prevention trial

Abstract

Drugs that inhibit cyclooxygenase (COX)-2 and the metabolism of arachidonic acid (ARA) to prostaglandin E2 are potent anti-inflammatory agents used widely in the treatment of joint and muscle pain. Despite their benefits, daily use of these drugs has been associated with hypertension, cardiovascular and gastrointestinal toxicities. It is now recognized that ARA is metabolized to a number of bioactive oxygenated lipids (oxylipins) by cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP450) enzymes. Currently, the contribution of individual variability in ARA metabolism in response to the COX-2 inhibitors and potential adverse effects remains poorly understood. Using patient samples from the randomized, placebo-controlled phase III selenium/celecoxib (Sel/Cel) trial for the prevention of colorectal adenomatous polyps, we analyzed plasma concentrations of 74 oxylipins in a subset of participants who received celecoxib (n = 90) or placebo (n = 95). We assessed the effect of celecoxib (with and without low dose aspirin) on circulating oxylipins and systolic blood pressure (SBP). Individual CYP450- and LOX- but not COX-derived metabolites were higher with celecoxib than placebo (P<0.05) and differences were greater among non-aspirin users. LOX derived 5- and 8-HETE were elevated with celecoxib and positively associated with systolic blood pressure (P = 0.011 and P = 0.019 respectively). 20-HETE, a prohypertensive androgen-sensitive CYP450 metabolite was higher with celecoxib absent aspirin and was positively associated with SBP in men (P = 0.040) but not women. Independent of celecoxib or aspirin, LOX derived metabolites from ARA were strongly associated with SBP including 5- and 8-HETE. These findings support oxylipins, particularly the ARA LOX-derived, in blood pressure control and indicate that pharmacologic inhibition of COX-2 has effects on LOX and CYP450 ARA metabolism that contribute to hypertension in some patients.

Fig 1. Arachidonic acid (ARA) pathway.

ARA is metabolized by three enzyme families, cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP450), to produce numerous bioactive metabolites called oxylipins. Enzymes are shown in grey boxes. Oxylipin class and biological activity are outlined in black below the oxylipins they represent. The COX arm produces prostaglandins and thromboxanes that are pro-inflammatory, can cause pain, and can stimulate chemokine production. The LOX arm produces lipoxins, leukotrienes, and hydroxyeicosatetraenoic acids that are also pro-inflammatory and can stimulate chemokine production, with the exception of LXA₄ which is anti-inflammatory. The CYP450 arm produces epoxyeicosatrienoic acids that decrease inflammation and are cardioprotective; however, these oxylipins are quickly metabolized by soluble epoxide hydrolase (sEH) to produce epoxyeicosatrienoic acid diols that are pro-inflammatory as well as cardiotoxic. The CYP450 arm also produces 20-hydroxyeicosatetraenoic acid (20-HETE), which is pro-inflammatory and cardiotoxic. Only oxylipins from the ARA pathway that were quantified on our analytical platform are depicted, excluding THF diol which is produced from multiple epoxyeicosatrienoic acids.

Fig 2. Pathway-based differences for all participants: Celecoxib (n = 90) versus placebo (n = 95).

(A) Summed oxylipins from ω-3 CYP450, ω-6 CYP450, and ω-6 LOX pathway arms. Asterisk (*) indicates P = 0.054. (B) Summed oxylipins from ω-3 LOX, ω-3 COX, and ω-6 COX pathways arms. Note that A and B are on different scales. Different colors represent the sum of all quantified oxylipins in a given pathway arm.

Fig 3. Celecoxib (n = 54) versus placebo (n = 49) among aspirin non-users only.

(A) Summed oxylipins from ω-3 CYP450, ω-6 CYP450, and ω-6 LOX pathway arms. Asterisk (*) indicates P = 0.032. (B) Summed oxylipins from ω-3 LOX, ω-3 COX, and ω-6 COX pathways arms. Note that A and B are on different scales. Different colors represent the sum of all quantified oxylipins in a given pathway arm. (C) Overlapping box plots showing significantly different individual oxylipins between placebo (gray) and celecoxib (pink) groups. (D) Median (IQR) levels of oxylipins that are significantly different between groups, with Wilcoxon rank-sum test P-values. Note that the median value for 8-HETE is below the limit of quantitation (< 0.0008 nM).

Fig 4. Celecoxib (n = 36) versus placebo (n = 46) among aspirin users only.

(A) Summed oxylipins from ω-3 CYP450, ω-6 CYP450, and ω-6 LOX pathway arms. (B) Summed oxylipins from ω-3 LOX, ω-3 COX, and ω-6 COX pathways arms. Note that A and B are on different scales. Different colors represent the sum of all quantified oxylipins in a given pathway arm. (C) Overlapping box plots showing significantly different individual oxylipins between placebo (gray) and celecoxib (pink) groups. (D) Median (IQR) levels of oxylipins that are significantly different between groups, with Wilcoxon rank-sum test P-values. Note that the median value for 8-HETE among the Placebo is below the limit of quantitation (< 0.0008 nM).

Fig 5. No aspirin (n = 103) versus aspirin (n = 82) among all participants.

(A) Summed oxylipins from ω-3 CYP450, ω-6 CYP450, and ω-6 LOX pathway arms. (B) Summed oxylipins from ω-3 LOX, ω-3 COX, and ω-6 COX pathways arms. Note that A and B are on different scales. Different colors represent the sum of all quantified oxylipins in a given pathway arm. (C) Overlapping box plots showing significantly different individual oxylipins between aspirin non-users (gray) and users (pink). (D) Median (IQR) levels of oxylipins that are significantly different between groups, with Wilcoxon rank-sum test P-values.

Fig 6. No NSAID (n = 49) versus any NSAID (aspirin and/or celecoxib; n = 136) among all participants.

(A) Summed oxylipins from ω-3 CYP450, ω-6 CYP450, and ω-6 LOX pathway arms. Asterisk (*) indicates P = 0.036. (B) Summed oxylipins from ω-3 LOX, ω-3 COX, and ω-6 COX pathways arms. Note that A and B are on different scales. Different colors represent the sum of all quantified oxylipins in a given pathway arm. (C) Overlapping box plots showing significantly different individual oxylipins between NSAID non-users (gray) and users (pink). (D) Median (IQR) levels of oxylipins that are significantly different between groups, with Wilcoxon rank-sum test P-values. Note that the median value for 8-HETE is below the limit of quantitation (< 0.0008 nM).