Biosynthesis of 15-deoxy-Δ12,14-PGJ2 and the ligation of PPARγ
L. Chastine Bell-Parikh, … , Muredach Reilly, Garret A. FitzGerald
L. Chastine Bell-Parikh, … , Muredach Reilly, Garret A. FitzGerald
Published September 15, 2003
Citation Information: J Clin Invest. 2003;112(6):945-955. https://doi.org/10.1172/JCI18012.
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Article Cell biology

Biosynthesis of 15-deoxy-Δ12,14-PGJ2 and the ligation of PPARγ

Abstract

15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) has been identified as an endogenous ligand for PPARγ, inducing adipogenesis in vitro. Additional roles for this molecule in the propagation and resolution of inflammation, ligation of NF-κB, and mediation of apoptosis have been proposed. However, quantitative, physiochemical evidence for the formation of 15d-PGJ2 in vivo is lacking. We report that 15d-PGJ2 is detectable using liquid chromatography–mass spectrometry–mass spectrometry at low picomolar concentrations in the medium of 3T3-L1 preadipocytes. However, despite induction of COX-2, production of PGs, including 15d-PGJ2, does not increase during adipocyte differentiation, a process unaltered by COX inhibition. 15d-PGJ2 is detectable as a minor product of COX-2 in human urine. However, its biosynthesis is unaltered during or after COX activation in vivo by LPS. Furthermore, the biosynthesis of 15d-PGJ2 is not augmented in the joint fluid of patients with arthritis, nor is its urinary excretion increased in patients with diabetes or obesity. 15d-PGJ2 is not the endogenous mediator of PPARγ-dependent adipocyte activation and is unaltered in clinical settings in which PPARγ activation has been implicated.

Authors

L. Chastine Bell-Parikh, Tomomi Ide, John A. Lawson, Peter McNamara, Muredach Reilly, Garret A. FitzGerald

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Biosynthesis of 15d-PGJ2 in humans. (a) Varied impact of COX inhibition ...
Biosynthesis of 15d-PGJ2 in humans. (a) Varied impact of COX inhibition on PG metabolites and a auto-oxidative product of arachidonic acid. Urine collections were obtained before and after aspirin (81 mg/d × 6 days) as described in the Methods section. The effects of a COX inhibitor on 15d-PGJ2 formation are compared with markers of COX-dependent (Tx-M and PGI-M) and COX-independent, free radical catalyzed isoprostane (8,12-iso-iPF2α-VI). Tx-M = 2,3-dinor TxB2. *P < 0.05. (b) COX-2 is the dominant source of 15d-PGJ2 biosynthesis in humans. 15d-PGJ2 levels in control volunteers (n = 21) were compared with those treated with the COX-2 selective NSAID celecoxib (n = 6) or nonselective ibuprofen (n = 5) (800 mg), administered acutely 30 minutes before urine collection. *P < 0.05; **P < 0.01. (c) Biosynthesis of PGI2, but not 15d-PGJ2, is altered during an acute inflammatory response in humans. Volunteers (n = 6) received LPS (4 ng/kg). PGI-M (2,3-dinor 6-keto-PGF1α) was measured at multiple time points and is plotted as the mean ± SD (dotted line). For 15d-PGJ2 measurements, urine was collected before LPS treatment (–2 to 0 hours) and at time points corresponding to peak inflammatory (4–6 hours) and resolution (16–24 hours) phases of response. Each individual is represented by a unique symbol that is conserved across time points. Median levels are indicated by horizontal lines. (d) Biosynthesis of 15d-PGJ2 is unaltered in diabetes or obesity. 15d-PGJ2 levels in healthy individuals are shown in comparison to obese (BMI ≥ 30) and nonobese (BMI < 30) patients with noninsulin-dependent type 2 diabetes. Median levels are indicated by horizontal lines.