prostaglandin-d2 and ciprofibrate

To determine whether homocysteine (Hcy)-mediated activation of endocardial endothelial (EE) cells is ameliorated by peroxisome proliferator-activated receptor (PPAR), we isolated EE cells from mouse endocardium. Matrix metalloproteinase (MMP) activity and intercellular adhesion molecule (ICAM)-1 in EE cells were measured in the presence and absence of Hcy, and ciprofibrate (CF; PPAR-alpha agonist) or 15-deoxy-Delta(12,14)-prostaglandin J(2) (PGJ(2); PPAR-gamma agonist) by zymography and Western blot analyses, respectively. Results suggest that Hcy-mediated MMP activation and ICAM-1 expression are ameliorated by CF and PGJ(2). To test the hypothesis that Hcy competes with other ligands for binding to PPARalpha and -gamma, we prepared cardiac nuclear extracts. Extracts were loaded onto an Hcy-cellulose affinity column. Bound proteins were eluted with CF and PGJ(2). To determine conformational changes in PPAR upon binding to Hcy, we measured PPAR fluorescence at 334 nm. Dose-dependent increase in PPAR fluorescence demonstrated a primary binding affinity of 0.32 +/- 0.06 microM. There was dose-dependent quenching of PPAR fluorescence by fluorescamine-homocysteine (F-Hcy). PPAR-alpha fluorescence quenching was abrogated by the addition of CF but not by PGJ(2). PPAR-gamma fluorescence quenching was abrogated by the addition of PGJ(2) but not by CF. These results suggest that Hcy competes with CF and PGJ(2) for binding to PPAR-alpha and -gamma, respectively, indicating a role of PPAR in amelioration of Hcy-mediated EE dysfunction.

Topics: Animals; Binding, Competitive; Cells, Cultured; Clofibric Acid; Dose-Response Relationship, Drug; Endocardium; Endothelium, Vascular; Fibric Acids; Homocysteine; Intercellular Adhesion Molecule-1; Ligands; Matrix Metalloproteinases; Mice; Myocardium; Prostaglandin D2; Protein Conformation; Receptors, Cytoplasmic and Nuclear; Transcription Factors

Peroxisome proliferator-activated receptors play an important role in the differentiation of different cell lines. In this study we demonstrate that PPAR-alpha ligands (clofibrate and ciprofibrate) and PPAR-gamma ligands (troglitazone and 15d-prostaglandin J2) inhibit growth and induce monocytic differentiation in HL-60 cells, whereas only PPAR-gamma ligands inhibit growth of U937 cells. Differentiation was demonstrated by the analysis of surface antigen expression CD11b and CD14, and by the characteristic morphological changes. PPAR-gamma ligands are more effective than PPAR-alpha ligands in the inhibition of cell growth and in the induction of differentiation. The physiological product of lipid peroxidation, 4-hydroxynonenal (HNE), which alone induces granulocytic-like differentiation of HL-60 cells, potentiates the monocytic differentiation induced by ciprofibrate, troglitazone, and 15d-prostaglandin J2. The same HNE treatment significantly inhibits U937 cell growth and potentiates the inhibition of cell growth in PPAR-gamma ligand-treated cells. However, HNE does not induce a significant number of CD14-positive U937 cells. HNE causes a great increase of PPAR-gamma expression in both HL-60 and U937 cells, whereas it does not modify the PPAR-alpha expression. This observation may account for the high synergistic effect displayed by HNE and PPAR-gamma ligands in the inhibition of cell growth and differentiation induction. These results represent the first evidence of the involvement of a product of lipid peroxidation in the modulation of PPAR ligand activity and suggest a relationship between HNE and PPAR ligand pathways in leukemic cell growth and differentiation.

Topics: Aldehydes; Cell Differentiation; Cell Division; Chromans; Clofibrate; Clofibric Acid; Drug Synergism; Fibric Acids; HL-60 Cells; Humans; Ligands; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Thiazoles; Thiazolidinediones; Time Factors; Transcription Factors; Troglitazone; U937 Cells

To test the hypothesis that homocysteine induces constrictive vascular remodeling by inactivating peroxisome proliferator-activated receptor (PPAR), aortic endothelial cells (ECs) and smooth muscle cells (SMCs) were isolated. Collagen gels were prepared, and ECs or SMCs (10(5)) or SMCs + ECs (10(4)) were incorporated into the gels. To characterize PPAR, agonists of PPAR-alpha [ciprofibrate (CF)] and PPAR-gamma [15-deoxy-12,14-prostaglandin J(2) (PGJ(2))] were used. To determine the role of disintegrin metalloproteinase (DMP), cardiac inhibitor of metalloproteinase (CIMP) was used in collagen gels. Gel diameter at 0 h was 14.1 +/- 0.2 mm and was unchanged up to 24 h as measured by a digital micrometer. SMCs reduce gel diameter to 10.5 +/- 0.4 mm at 24 h. Addition of homocysteine to SMCs reduces further the gel diameter to 8.0 +/- 0.2 mm, suggesting that SMCs induce contraction and that the contraction is further enhanced by homocysteine. Addition of ECs and SMCs reduces gel diameter to 12.0 +/- 0.3 mm, suggesting that ECs play a role in collagen contraction. Only PGJ(2), not CF, inhibits SMC contraction. However, both PGJ(2) and CF inhibit contraction of ECs and SMCs + ECs. Addition of anti-DMP blocks SMC- as well as homocysteine-mediated contraction. However, CIMP inhibits only homocysteine-mediated contraction. The results suggest that homocysteine may enhance vascular constrictive remodeling by inactivating PPAR-alpha and -gamma in ECs and PPAR-gamma in SMCs.

Topics: Antineoplastic Agents; Aorta; Cell Culture Techniques; Clofibric Acid; Collagen; Culture Media, Serum-Free; Disintegrins; Endothelium, Vascular; Fibric Acids; Homocysteine; Humans; Metalloendopeptidases; Muscle, Smooth; Peroxisome Proliferators; Platelet Aggregation Inhibitors; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Transcription Factors