The Cyclopentenone Prostaglandin 15-Deoxy- -Prostaglandin J2 Attenuates the Development of Acute and Chronic Inflammation

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligandactivated transcription factors that are related to retinoid, steroid, and thyroid hormone receptors. The PPARreceptor subtype seems to play a pivotal role in the regulation of cellular proliferation and inflammation. Recent evidence also suggests that the cyclopentenone prostaglandin (PG) 15-deoxy-PGJ2 (15d-PGJ2), which is a metabolite of prostaglandin D2, functions as an endogenous ligand for PPAR. We postulated that 15d-PGJ2 would attenuate inflammation. In the present study, we have investigated the effects of 15d-PGJ2 of acute and chronic inflammation (carrageenan-induced pleurisy and collagen-induced arthritis, respectively) in animal models. We report for the first time, to our knowledge, that 15d-PGJ2 (given at 10, 30, or 100 g/kg i.p. in the pleurisy model or at 30 g/kg i.p every 48 h in the arthritis model) exerts potent antiinflammatory effects (e.g., inhibition of pleural exudate formation, mononuclear cell infiltration, delayed development of clinical indicators, and histological injury) in vivo. Furthermore, 15d-PGJ2 reduced the increase in the staining (immunohistochemistry) for nitrotyrosine and poly (ADP-ribose) polymerase and the expression of inducible nitric-oxide synthase and cyclooxygenase-2 in the lungs of carrageenan-treated mice and in the joints from collagen-treated mice. Thus, 15d-PGJ2 reduces the development of acute and chronic inflammation. Therefore, the cyclopentenone prostaglandin 15d-PGJ2 may be useful in the therapy of acute and chronic inflammation. The cyclopentenone prostaglandin PGJ2 is formed by dehydration within the cyclopentenone ring of the endogenous prostaglandin PGD2. PGJ2 is metabolized further to yield -PGJ2 and 15-deoxy-PGJ2 (15d-PGJ2). Several members of the cyclopentenone family of prostaglandins possess antineoplastic, antiviral activity and anti-inflammatory properties (Straus and Glass, 2001). Most actions of the cyclopentenone prostaglandins seem to be secondary to their interaction with other cellular target proteins rather than mediated by binding to G-protein-coupled prostanoid receptors. For instance, 15d-PGJ2 is a highaffinity ligand for PPAR. PPARis a nuclear hormone receptor that regulates gene expression by heterodimerizing with the retinoid X receptor. Binding of the activated heterodimer to promoter region of specific target genes results in either the activation or the suppression of the target gene. Various PPARligands have been reported to possess antiinflammatory properties in vitro (Jiang et al., 1998) and in vivo (see below). It is possible that PPARtrans-represses the expression of pro-inflammatory mediators at the transcriptional level by inhibiting NFB, signal transducers and activators of transcription-1, and activation protein-1 signaling (Ricote et al., 1998). Other activities of the cyclopentenone prostaglandins are mediated by the reactive , -unsaturated carbonyl group located in the cyclopentenone ring. For instance, 15d-PGJ2 attenuates the activation of the transcription factor NFB by preventing the phosphorylation of its inhibitor protein by C.T. is a Senior Fellow of the British Heart Foundation (FS 96/018) and P.K.C. was supported by The National Kidney Research Fund (Grant R41/2/ 2000). ABBREVIATIONS: 15d-PGJ2, 15-deoxy-prostaglandin J2; PPAR, peroxisome proliferator-activated receptor; NFB, nuclear factorB; NO, nitric oxide; iNOS, inducible nitric-oxide synthase; PARP, poly(ADP-ribose) polymerase; CIA, collagen-induced arthritis; COX, cyclooxygenase; DMSO, dimethyl sulfoxide; CII, bovine type 2 collagen; CFA, complete Freund’s adjuvant; MPO, myeloperoxidase; PMN, polymorphonuclear leukocyte; MDA, malondialdehyde; PBS, phosphate-buffered saline; ROS, reactive oxygen species; TNF, tumor necrosis factor; IL, interleukin. 0026-895X/02/6105-997–1007$7.00 MOLECULAR PHARMACOLOGY Vol. 61, No. 5 Copyright © 2002 The American Society for Pharmacology and Experimental Therapeutics 1158/979681 Mol Pharmacol 61:997–1007, 2002 Printed in U.S.A. 997 at A PE T Jornals on July 0, 2018 m oharm .aspeurnals.org D ow nladed from inhibitory kinase kinase (Rossi et al., 1997). It is now widely accepted that 15d-PGJ2 attenuates the NFB–mediated transcriptional activation of many pro-inflammatory genes by PPAR–dependent and -independent mechanisms (Straus and Glass, 2001). For instance, 15d-PGJ2 attenuates the formation of the cytokines TNFand IL-12 (Drew and Chavis, 2001), the expression of the adhesion molecules vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 (Pasceri et al., 2000) and the expression of the inducible, pro-inflammatory proteins cyclooxygenase-2 (COX-2), cytosolic phospholipase A2 (Tsubouchi et al., 2001), and inducible nitric-oxide (NO) synthase (iNOS) (Ricote et al., 1998; Colville-Nash et al., 1998). However, there is also evidence that 15d-PGJ2 may enhance the formation of the pro-inflammatory chemokine IL-8 in human macrophages/ monocytes stimulated with endotoxin in a PPAR-dependent fashion (Zhang et al., 2001). A recent report by Kawahito et al. (2000) documents that 15d-PGJ2 and the PPARligand troglitazone reduce the degree of inflammation (i.e., suppression of pannus formation and mononuclear cell infiltration) associated with adjuvantinduced arthritis in female Lewis rats. This study was designed to gain a better understanding of the effects of 15dPGJ2 in rodent models of acute and chronic inflammation. To achieve this goal, we have investigated the effects of this cyclopentenone prostaglandin in rodent models of acute (carrageenan-induced pleurisy) and chronic [collagen-induced arthritis (CIA)] inflammation. In particular, we have investigated the effects of 15d-PGJ2 on the lung injury associated with carrageenan-induced pleurisy and on the joint injury associated with collagen-induced arthritis. To gain a better insight into the mechanism(s) of action of the observed antiinflammatory effects of 15d-PGJ2, we have also investigated the effects of 15d-PGJ2 on expression of iNOS and COX-2, the nitration of cellular proteins by peroxynitrite, and the activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP). Materials and Methods Animals. Nine-week-old male BALB/c and DBA/1J mice (weight, 20–25 g; Charles River, Milan, Italy) were used for these studies. The animals were housed in a controlled environment and provided with standard rodent chow and water. Animal care was in compliance with Italian regulations on protection of animals used for experimental and other scientific purposes (D.M. 116192) and with European Economic Community regulations (O.J. of E.C. L358/1 12/18/1986). Experimental Groups. For the pleurisy study, 60 BALB/c mice were allocated into one of the following groups: 1) administration of carrageenan only (CAR group, n 10); 2) 15d-PGJ2 given as an i.p. bolus 15 min before carrageenan (10, 30, or 100 g/kg) (CAR 15d-PGJ2 group, n 30); 3) administration of vehicle for 15d-PGJ2 [10% dimethyl sulfoxide (DMSO)] administered alone (VEH group, n 10); and 4) a sham-operated group in which identical surgical procedures to the CAR group was performed, except that the 10% DMSO was administered instead of carrageenan (SHAM group, n