leptin and pirinixic-acid

Infrapatellar fat pad (IPFP) might be involved in osteoarthritis (OA) by production of cytokines. It was hypothesised that production of cytokines is sensitive to environmental conditions.. To evaluate cytokine production by IPFP in response to interleukin (IL)1β and investigate the ability to modulate this response with an agonist for peroxisome proliferator activated receptor α (PPARα), which is also activated by lipid-lowering drugs such as fibrates.. Cytokine secretion of IPFP was analysed in the medium of explant cultures of 29 osteoarthritic patients. IPFP (five donors) and synovium (six donors) were cultured with IL-1β and PPARα agonist Wy14643. Gene expression of IL-1β, monocyte chemoattractant protein (MCP1), (IL-6, tumour necrosis factor (TNF)α, leptin, vascular endothelial growth factor (VEGF), IL-10, prostaglandin-endoperoxide synthase (PTGS)2 and release of TNFα, MCP1 and prostaglandin E(2) were compared with unstimulated IPFP and synovium explants.. IPFP released large amounts of inflammatory cytokines, adipokines and growth factors. IL-1β increased gene expression of PTGS2, TNFα, IL-1β, IL-6 and VEGF and increased TNFα release in IPFP. MCP1, leptin, IL-10 gene expression and MCP1, leptin and PGE(2) release did not increase significantly. Synovium responded to IL-1β similarly to IPFP, except for VEGF gene expression. Wy14643 decreased gene expression of PTGS2, IL-1β, TNFα, MCP1, VEGF and leptin in IPFP explants and IL-1β, TNFα, IL-6, IL-10 and VEGF in synovium that responded to IL-1β.. IPFP is an active tissue within the joint. IPFP cytokine production is increased by IL-1β and decreased by a PPARα agonist. The effects were similar to effects seen in synovium. Fibrates may represent a potential disease-modifying drug for OA by modulating inflammatory properties of IPFP and synovium.

Topics: Adipose Tissue; Aged; Aged, 80 and over; Anticholesteremic Agents; Chemokine CCL2; Cyclooxygenase 2; Cytokines; Dinoprostone; Gene Expression; Humans; Interleukin-10; Interleukin-1beta; Interleukin-6; Leptin; Middle Aged; Osteoarthritis, Knee; Patella; PPAR alpha; Pyrimidines; Tissue Culture Techniques; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A

Fatty acid elongases and desaturases play an important role in hepatic and whole body lipid composition. We examined the role that key transcription factors played in the control of hepatic elongase and desaturase expression. Studies with peroxisome proliferator-activated receptor alpha (PPARalpha)-deficient mice establish that PPARalpha was required for WY14643-mediated induction of fatty acid elongase-5 (Elovl-5), Elovl-6, and all three desaturases [Delta(5) desaturase (Delta(5)D), Delta(6)D, and Delta(9)D]. Increased nuclear sterol-regulatory element binding protein-1 (SREBP-1) correlated with enhanced expression of Elovl-6, Delta(5)D, Delta(6)D, and Delta(9)D. Only Delta(9)D was also regulated independently by liver X receptor (LXR) agonist. Glucose induction of l-type pyruvate kinase, Delta(9)D, and Elovl-6 expression required the carbohydrate-regulatory element binding protein/MAX-like factor X (ChREBP/MLX) heterodimer. Suppression of Elovl-6 and Delta(9)D expression in livers of streptozotocin-induced diabetic rats and high fat-fed glucose-intolerant mice correlated with low levels of nuclear SREBP-1. In leptin-deficient obese mice (Lep(ob/ob)), increased SREBP-1 and MLX nuclear content correlated with the induction of Elovl-5, Elovl-6, and Delta(9)D expression and the massive accumulation of monounsaturated fatty acids (18:1,n-7 and 18:1,n-9) in neutral lipids. Diabetes- and obesity-induced changes in hepatic lipid composition correlated with changes in elongase and desaturase expression. In conclusion, these studies establish a role for PPARalpha, LXR, SREBP-1, ChREBP, and MLX in the control of hepatic fatty acid elongase and desaturase expression and lipid composition.

Topics: Acetyltransferases; Adult; Animals; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Diabetes Mellitus; Fatty Acid Desaturases; Fatty Acid Elongases; Female; Glucose; Humans; Hydrocarbons, Fluorinated; Insulin; Leptin; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Middle Aged; Obesity; PPAR alpha; Pyrimidines; Rats; Rats, Sprague-Dawley; Sterol Regulatory Element Binding Protein 1; Sulfonamides

The recently identified uncoupling protein-3 (UCP-3) gene, predicted to encode a new member of the family of uncoupling proteins, is preferentially expressed in skeletal muscle and has been related to phenotypes of obesity and type 2 diabetes. We have established that during mouse ontogeny, the expression of the UCP-3 gene is switched on in skeletal muscle just after birth. The induction of UCP-3 gene expression is dependent on the initiation of suckling and particularly on lipid intake. Treatment of newborn mice with activators of peroxisome proliferator-activated receptors (PPARs), such as clofibrate, bezafibrate, or (4-chloro-6-(2,3-xylidine)-pirimidinylthio)acetic acid (WY 14,643), mimics the action of food intake on UCP-3 gene expression. The specific ligand of PPAR-alpha WY 14,643 induces UCP-3 gene expression in a time- and dose-dependent manner, whereas the thiazolidinedione BRL 49653, specific for PPAR-gamma, has no effect. These treatments act without altering circulating free fatty acids. During development, skeletal muscle expresses constitutive levels of PPAR-delta mRNA, whereas expression of the PPAR-gamma gene is undetectable. PPAR-alpha gene expression is developmentally regulated in muscle as it is first expressed at birth, just before UCP-3 gene induction occurs. The induction of UCP-3 gene expression by WY 14,643 is impaired in skeletal muscle of premature neonates, which do not express PPAR-alpha. It is proposed that the UCP-3 gene is predominantly regulated in neonatal muscle by PPAR-alpha activation.

Topics: Animals; Bezafibrate; Carrier Proteins; Clofibrate; DNA-Binding Proteins; Eating; Fatty Acids, Nonesterified; Female; Gene Expression Regulation, Developmental; Hypolipidemic Agents; Ion Channels; Leptin; Male; Mice; Mitochondria, Muscle; Mitochondrial Proteins; Muscle Development; Muscle, Skeletal; Peroxisome Proliferators; Proteins; Pyrimidines; Receptors, Cytoplasmic and Nuclear; Recombinant Proteins; RNA, Messenger; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors; Transcriptional Activation; Uncoupling Protein 3

Lack of leptin (ob) protein causes obesity in mice. The leptin gene product is important for normal regulation of appetite and metabolic rate and is produced exclusively by adipocytes. Leptin mRNA was induced during the adipose conversion of 3T3-L1 cells, which are useful for studying adipocyte differentiation and function under controlled conditions. We studied leptin regulation by antidiabetic thiazolidinedione compounds, which are ligands for the adipocyte-specific nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) that regulates the transcription of other adipocyte-specific genes. Remarkably, leptin gene expression was dramatically repressed within a few hours after thiazolidinedione treatment. The ED50 for inhibition of leptin expression by the thiazolidinedione BRL49653 was between 5 and 50 nM, similar to its Kd for binding to PPARgamma. The relatively weak, nonthiazolidinedione PPAR activator WY 14,643 also inhibited leptin expression, but was approximately 1000 times less potent than BRL49653. These results indicate that antidiabetic thiazolidinediones down-regulate leptin gene expression with potencies that correlate with their abilities to bind and activate PPARgamma.

Topics: 3T3 Cells; Adipocytes; Animals; Base Sequence; Gene Expression Regulation; Hypoglycemic Agents; Leptin; Mice; Molecular Sequence Data; Obesity; Oligodeoxyribonucleotides; Protein Binding; Proteins; Pyrimidines; Receptors, Cytoplasmic and Nuclear; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors