Peroxisome Proliferator-activated Receptor Delta Agonist Research Articles

Development of a Robust Read-Across Model for the Prediction of Biological Potency of Novel Peroxisome Proliferator-Activated Receptor Delta Agonists.

A robust predictive model was developed using 136 novel peroxisome proliferator-activated receptor delta (PPARδ) agonists, a distinct subtype of lipid-activated transcription factors of the nuclear receptor superfamily that regulate target genes by binding to characteristic sequences of DNA bases. The model employs various structural descriptors and docking calculations and provides predictions of the biological activity of PPARδ agonists, following the criteria of the Organization for Economic Co-operation and Development (OECD) for the development and validation of quantitative structure-activity relationship (QSAR) models. Specifically focused on small molecules, the model facilitates the identification of highly potent and selective PPARδ agonists and offers a read-across concept by providing the chemical neighbours of the compound under study. The model development process was conducted on Isalos Analytics Software (v. 0.1.17) which provides an intuitive environment for machine-learning applications. The final model was released as a user-friendly web tool and can be accessed through the Enalos Cloud platform's graphical user interface (GUI).

A Phase 3 Trial of Seladelpar in Primary Biliary Cholangitis

BackgroundEffective treatments for patients with primary biliary cholangitis are limited. Seladelpar, a peroxisome proliferator–activated receptor delta agonist, has potential benefits.MethodsIn this phase 3, 12-month, double-blind, placebo-controlled trial, we randomly assigned (in a 2:1 ratio) patients who had had an inadequate response to or who had a history of unacceptable side effects with ursodeoxycholic acid to receive oral seladelpar at a dose of 10 mg daily or placebo. The primary end point was a biochemical response, which was defined as an alkaline phosphatase level less than 1.67 times the upper limit of the normal range, with a decrease of 15% or more from baseline, and a normal total bilirubin level at month 12. Key secondary end points were normalization of the alkaline phosphatase level at month 12 and a change in the score on the pruritus numerical rating scale (range, 0 [no itch] to 10 [worst itch imaginable]) from baseline to month 6 among patients with a baseline score of at least 4 (indicating moderate-to-severe pruritus).ResultsOf the 193 patients who underwent randomization and treatment, 93.8% received ursodeoxycholic acid as standard-of-care background therapy. A greater percentage of the patients in the seladelpar group than in the placebo group had a biochemical response (61.7% vs. 20.0%; difference, 41.7 percentage points; 95% confidence interval [CI], 27.7 to 53.4, P<0.001). Normalization of the alkaline phosphatase level also occurred in a greater percentage of patients who received seladelpar than of those who received placebo (25.0% vs. 0%; difference, 25.0 percentage points; 95% CI, 18.3 to 33.2, P<0.001). Seladelpar resulted in a greater reduction in the score on the pruritus numerical rating scale than placebo (least-squares mean change from baseline, −3.2 vs. −1.7; least-squares mean difference, −1.5; 95% CI, −2.5 to −0.5, P=0.005). Adverse events were reported in 86.7% of the patients in the seladelpar group and in 84.6% in the placebo group, and serious adverse events in 7.0% and 6.2%, respectively.ConclusionsIn this trial involving patients with primary biliary cholangitis, the percentage of patients who had a biochemical response and alkaline phosphatase normalization was significantly greater with seladelpar than with placebo. Seladelpar also significantly reduced pruritus among patients who had moderate-to-severe pruritus at baseline. The incidence and severity of adverse events were similar in the two groups. (Funded by CymaBay Therapeutics; RESPONSE ClinicalTrials.gov number, NCT04620733; EudraCT number, 2020-004348-27.)

A phase II, randomized, open-label, 52-week study of seladelpar in patients with primary biliary cholangitis

We examined the efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, in adults with primary biliary cholangitis (PBC) at risk of disease progression (alkaline phosphatase [ALP] ≥1.67xupper limit of normal [ULN]) who were receiving or intolerant to ursodeoxycholic acid. In this 52-week, phase II, dose-ranging, open-label study, patients were randomized (1:1) to seladelpar 5mg/day (n=53) or 10mg/day (n=55) or assigned to 2mg/day (n=11; United Kingdom sites after interim analysis) for 12 weeks. Doses could then be uptitrated to 10mg/day. The primary efficacy endpoint was ALP change from baseline to Week8. Mean baseline ALP was 300, 345, and 295U/L in the 2mg, 5mg, and 10mg cohorts, respectively. Twenty-one percent of patients had cirrhosis, 71% had pruritus. At Week 8, mean±standard error ALP reductions from baseline were 26±2.8%, 33±2.6%, and 41±1.8% in the 2mg (n=11), 5mg (n=49), and 10mg (n=52) cohorts (all p≤0.005), respectively. Responses were maintained or improved at Week 52, after dose escalation in 91% and 80% of the 2mg and 5mg cohorts, respectively. At Week 52, composite response (ALP <1.67xULN, ≥15% ALP decrease, and normal total bilirubin) rates were 64%, 53%, and 67%, and ALP normalization rates were 9%, 13%, and 33% in the 2mg, 5mg, and 10mg cohorts, respectively. Pruritus visual analog scale score was decreased in the 5mg and 10mg cohorts. There were no treatment-related serious adverse events, and 4 patients discontinued due to adverse events. Seladelpar demonstrated robust, dose-dependent, clinically significant, and durable improvements in biochemical markers of cholestasis and inflammation in patients with PBC at risk of disease progression. Seladelpar appeared safe and well tolerated and was not associated with any increase in pruritus. NCT02955602 CLINICALTRIALSREGISTER. 2016-002996-91 LAY SUMMARY: Current treatment options for patients living with primary biliary cholangitis (PBC) are not optimal due to inadequate effectiveness or undesirable side effects. Patients with PBC who took seladelpar, a new treatment being developed for PBC, at increasing doses (2, 5, or 10mg/day) for 1 year had clinically significant, dose-dependent improvements in key liver tests. Treatment appeared safe and was not associated with any worsening in patient self-reported itch scores.

Peroxisome Proliferator-Activated Receptor Delta Agonist (PPAR- δ) and Selective Androgen Receptor Modulator (SARM) Abuse: Clinical, Analytical and Biological Data in a Case Involving a Poisonous Combination of GW1516 (Cardarine) and MK2866 (Ostarine)

A 43-year-old male, sport coach, presented him-self at the Emergency unit of a local hospital for epigastric pain, myalgia pain and severe headache. He claimed having used for some days a combination of GW1516 (cardarine), a peroxisome proliferator-activated receptor delta agonist (PPAR- δ) and MK2866 (ostarine), a selective androgen receptor modulator (SARM) to gain skeletal muscles. Cytolysis with marked increase of alanine aminotransferase or ALT (up to 922 UI/L) and aspartate aminotransferase or AST (up to 2558 UI/L) and massive rhabdomyolysis with elevated creatine phosphokinase or CPK (up to 86435 UI/L) were the main unusual biochemistry parameters. Using a specific liquid chromatography coupled to tandem mass spectrometry method, cardarine and ostarine tested positive in blood at 403 and 1 ng/mL, respectively. In urine, due to extensive metabolism, the parent GW1516 was not identified, while ostarine was at 88 ng/mL. Finally, both drugs were identified in hair (2 cm in length, brown in colour), at 146 and 1105 pg/mg for cardarine and ostarine, respectively. This clearly demonstrates repetitive abuse over the last 2 months. Asthenia was persistent for 2 weeks and 6 weeks after the admission, the subject fully recovered.

Pregnancy-associated changes of peroxisome proliferator-activated receptor delta (PPARD) and cytochrome P450 family 21 subfamily A member 2 (CYP21A2) expression in the bovine corpus luteum.

We investigated gene expression profiles of the corpus luteum (CL) at the time of maternal recognition to evaluate the functional changes of the CL during early pregnancy in cows and help improve reproductive efficiency and avoid defective fetuses. Microarray analyses using a 15 K bovine oligo DNA microarray detected 30 differentially expressed genes and 266 differentially expressed genes (e.g., PPARD and CYP21A2) in the CL on pregnancy days 15 (P15) and 18 (P18), respectively, compared with the CL on day 15 (NP15) of non-pregnancy (n = 4 for each group). PPARD expression was the highest while the CYP21A2 expression was the lowest in P15 and P18 compared with that of NP15. These microarray results were validated by quantitative real-time PCR analysis. The addition of interferon-τ and supernatants derived from homogenized fetal trophoblast increased ISG15 and MX1 expressions in the cultured luteal tissue (P < 0.01), but did not affect PPARD and CYP21A2 expressions. PPARD expression in the luteal tissue was stimulated (P < 0.05) by GW0742, known as a selective PPARD agonist, and PPARD ligands (i.e., arachidonic, linoleic and linolenic acids). In contrast, CYP21A2 mRNA expression was not affected by both agonist and ligands. The concentration of prostaglandin (PG) E2 and PGF2α decreased after GW0742 stimulation and increased after arachidonic acid stimulation (P < 0.05). The addition of GW0742 and arachidonic acid increased progesterone (P4) concentration. Collectively, these findings suggest that high expression levels of PPARD and low expression levels of CYP21A2 in the CL during early pregnancy may support P4 production by bovine luteal cells.

Roads to the Fountain of Youth? Rejuvenating Intestinal Stem Cells.

The intestinal stem cells (ISCs) of old mice and humans exhibit a reduced capacity for regeneration and repair. Compromised intestinal function may play a key role in systemic aging-related changes: not only in the affected gut, but also in the nervous and cardiovascular systems. For example, progression of age-related neurodegenerative diseases such as Alzheimer's and Parkinson's has been linked to increased inflammation from gut microbiota in old mammals, which, in turn, may be linked bidirectionally with reduced ISC function. Intestinal organoid formation has been used to dissect the mechanisms of decline of ISC function. Alterations of the Wnt pathway, including downregulation of Wnt ligands in ISCs and upregulation of Wnt ligand inhibitor Notum in Paneth cells, and dysregulation of mTORC1 contribute to the observed age-related decline. Short-term fasting, caloric restriction, and peroxisome proliferator-activated receptor delta agonists have been reported to increase ISC function in adult mice. Moreover, the mTOR inhibitor rapamycin, NAD+ precursor nicotinamide riboside, and ABC99, a small molecule Notum inhibitor, have all been reported to rejuvenate ISC function in old mice and thus may have promise in humans. However, there is some controversy over the key mechanisms involved in loss of function of ISCs, which likely results, in part, from differences in how the in vitro organoid assays are performed. Moreover, how the microbiome modulates the function of ISCs and vice versa remains to be elucidated.

Treatment efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor delta agonist, in primary biliary cholangitis patients: 12- and 26-week analysis from an ongoing international, randomized, dose raging phase 2 study

Treatment efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor delta agonist, in primary biliary cholangitis patients: 12- and 26-week analysis from an ongoing international, randomized, dose raging phase 2 study

Enantioselective Synthesis of a Novel Thiazoline Core as a Potent Peroxisome Proliferator-Activated Receptor δ Agonist.

The convergent and enantioselective synthesis of a highly potent human peroxisome proliferator-activated receptor delta agonist is presented. More specifically, the thiazoline structure, which constitutes the biosynthetically distinctive core structure of pulicatin (a secondary metabolite of symbiotic bacteria), was synthesized from a commercially available and inexpensive chiral pool of l-threonine.

Abstract 11869: Identification of Human Lysophosphatidylcholine Acyltransferase 3 as a Novel Target Gene Regulated by Peroxisome Proliferator-activated Receptor Delta in Hepatic Cells and in Liver Tissue

Peroxisome proliferator-activated receptor delta (PPARD) is a transcription factor regulating many important genes involved in lipid and glucose metabolism. Hepatic lysophosphatidylcholine acyltransferase 3 (LPCAT3) plays critical functions in TG secretion and ER stress response due to its unique ability to catalyze the incorporation of polyunsaturated fatty acids into phospholipids. Previous studies identified liver X receptor as the transcription factor controlling LPCAT3 expression in liver tissue. Here we showed for the first time that the hepatic LPCAT3 gene is transcriptionally regulated by PPARD in vitro and in vivo . Treatments of HepG2, Huh-7, and Hepa 1-6 cells with PPARD specific agonists (L-165041 and GW0742) increased LPCAT3 mRNA levels 2-3 fold of control. Adenovirus-mediated knockdown of PPARD in HepG2 cells reduced the basal level of LPCAT3 mRNA by approximately 40% compared to control and further attenuated the induction of PPARD agonist on LPCAT3 gene expression. To demonstrate the direct regulation of PPARD on LPCAT3 gene transcription, we analyzed human LPCAT3 promoter sequence and identified two putative PPAR responsive elements (PPRE-1, -171; PPRE-2, -727) within 1 kb of the proximal LPCAT3 promoter. LPCAT3 promoter assays demonstrated strong inductions of the reporter activity by PPARD agonists. Mutational analysis of the human LPCAT3 promoter revealed that the PPRE-1 is involved in conferring responsiveness to PPARD agonist mediated transcriptional activity. Direct binding of PPARD to PPRE-1 sequence was demonstrated by chromatin immunoprecipitation and gel retardation assays. Finally, we provided in vivo evidence showing that activation of PPARD by L-165041 in mice increased LPCAT3 mRNA abundance in the liver. Altogether, these new findings identify LPCAT3 as a direct PPARD target gene and suggest a novel function of PPARD in regulation of phospholipid metabolism through LPCAT3.

Abstract B052: Peroxisome proliferator-activated receptor delta agonist GW501516 enhances the efficacy of adoptive cell therapy

Abstract Adoptive cell therapy (ACT) has demonstrated tremendous promise for the treatment of metastatic melanoma. Emerging evidence has indicated that memory CD8+ T cells (Tcm) are superior mediators of ACT than are effector CD8+ T cells (Teff) due to a superior ability to persist in vivo. Underpinning the survival advantage of Tcm is a shift in cellular metabolism away from aerobic glycolysis to instead favor fatty acid oxidation (FAO). This switch to FAO in Tcm requires the expression of carnitine palmitoyl transferase 1a (CPT1a), the rate-limiting enzyme of FAO. Here, we investigated the impact of the peroxisome proliferator-activated receptor (PPAR)δ/β agonist GW501516 (GW), an agent known to boost CPT1a expression and promote FAO in other tissues, on CD8+ T cell metabolism, function and performance in the murine B16-GP33 melanoma model. Via the activation of both PPARα and PPARδ/β we found that GW treatment increased CPT1a expression in activated CD8+ T cells. Using a metabolomics approach, we demonstrated that GW treatment increased the abundance of multiple different acylcarnitines, consistent with enhanced FAO. Unexpectedly, we also found that T cells activated in the presence of GW as well as inflammatory signals, either LPS-matured dendritic cells (DCs) or IL-12, demonstrated enhanced production of interferon-γ. This increase in interferon-γ correlated with increased expression of the transcription factor T-bet. Despite the high T-bet expression, a characteristic of short-lived effector cells, GW-treated CD8+ T cells activated by LPS-treated DCs demonstrated an enhanced ability to persist in vivo. They also demonstrated improved performance in our murine model of ACT. Thus, our data indicates that combined treatment of CD8+ T cells with GW and inflammatory signals can result in in Teff cell with improved ability to produce cytokines but that have also shifted their metabolism to increase FAO akin to Tcm, allowing for enhanced in vivo persistence. These data identify GW501516, and potentially other combined PPARα and PPARδ/β agonists currently being developed, as attractive candidates for further studies and rapid translation into clinical trials of ACT. Citation Format: Samuel Saibil, Michael St. Paul, Pamela Ohahsi. Peroxisome proliferator-activated receptor delta agonist GW501516 enhances the efficacy of adoptive cell therapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B052.

Peroxisome proliferator-activated receptor-delta agonist ameliorated inflammasome activation in nonalcoholic fatty liver disease.

To evaluate the inflammasome activation and the effect of peroxisome proliferator-activated receptors (PPAR)-δ agonist treatment in nonalcoholic fatty liver disease (NAFLD) models. Male C57BL/6J mice were classified according to control or high fat diet (HFD) with or without PPAR-δ agonist (GW) over period of 12 wk [control, HFD, HFD + lipopolysaccharide (LPS), HFD + LPS + GW group]. HepG2 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of GW. HFD caused glucose intolerance and hepatic steatosis. In mice fed an HFD with LPS, caspase-1 and interleukin (IL)-1β in the liver were significantly increased. Treatment with GW ameliorated the steatosis and inhibited overexpression of pro-inflammatory cytokines. In HepG2 cells, PA and LPS treatment markedly increased mRNA of several nucleotide-binding and oligomerization domain-like receptor family members (NLRP3, NLRP6, and NLRP10), caspase-1 and IL-1β. PA and LPS also exaggerated reactive oxygen species production. All of the above effects of PA and LPS were reduced by GW. GW also enhanced the phosphorylation of AMPK-α. PPAR-δ agonist reduces fatty acid-induced inflammation and steatosis by suppressing inflammasome activation. Targeting the inflammasome by the PPAR-δ agonist may have therapeutic implication for NAFLD.

Angiopoietin-Like 4 Mediates PPAR Delta Effect on Lipoprotein Lipase-Dependent Fatty Acid Uptake but Not on Beta-Oxidation in Myotubes

Peroxisome proliferator-activated receptor (PPAR) delta is an important regulator of fatty acid (FA) metabolism. Angiopoietin-like 4 (Angptl4), a multifunctional protein, is one of the major targets of PPAR delta in skeletal muscle cells. Here we investigated the regulation of Angptl4 and its role in mediating PPAR delta functions using human, rat and mouse myotubes. Expression of Angptl4 was upregulated during myotubes differentiation and by oleic acid, insulin and PPAR delta agonist GW501516. Treatment with GW501516 or Angptl4 overexpression inhibited both lipoprotein lipase (LPL) activity and LPL-dependent uptake of FAs whereas uptake of BSA-bound FAs was not affected by either treatment. Activation of retinoic X receptor (RXR), PPAR delta functional partner, using bexarotene upregulated Angptl4 expression and inhibited LPL activity in a PPAR delta dependent fashion. Silencing of Angptl4 blocked the effect of GW501516 and bexarotene on LPL activity. Treatment with GW501516 but not Angptl4 overexpression significantly increased palmitate oxidation. Furthermore, Angptl4 overexpression did not affect the capacity of GW501516 to increase palmitate oxidation. Basal and insulin stimulated glucose uptake, glycogen synthesis and glucose oxidation were not significantly modulated by Angptl4 overexpression. Our findings suggest that FAs-PPARdelta/RXR-Angptl4 axis controls the LPL-dependent uptake of FAs in myotubes, whereas the effect of PPAR delta activation on beta-oxidation is independent of Angptl4.

Peroxisome proliferator-activated receptor delta agonist attenuates nicotine suppression effect on human mesenchymal stem cell-derived osteogenesis and involves increased expression of heme oxygenase-1

Smoking has long been associated with osteoporosis, decreased bone mineral density, increased risk of bone fracture, and increased health costs. Nicotine, the main component of cigarette smoke, has major negative effects on bone metabolism and skeletal remodeling in vivo. Although osteoblasts and osteoblast-like cells have been used extensively to study the impact of nicotine, few studies have been performed on human mesenchymal stem cells (hMSCs). In this context, we examined the impact of nicotine on (a) hMSCs proliferation, (b) osteoblastic differentiation, (c) alkaline phosphatase (ALP) activity, and (d) expression of canonical genes during differentiation of hMSCs. MSCs isolated from human bone marrow were treated with different concentrations (0, 0.1, 1 and 10μM) of nicotine for 7days. Nicotine caused a dose-dependent decrease in cell proliferation, decreased heme oxygenase-1 (HO-1) expression (p<0.05) and attenuated osteogenesis (p<0.05) in hMSCs (45% reduction at day 14). In addition, nicotine caused a dose-dependent decrease in alizarin red staining for calcium and staining for ALP. Induction of HO-1 by peroxisome proliferator-activated receptor delta agonist (GW0742) prevented the effect of nicotine. Nicotine caused a dose-dependent reduction in the expression of BMP-2, a well-known marker for bone formation; however, this was prevented by GW0742 treatment. Therefore, induction of HO-1 prevents the deleterious effects of nicotine on osteogenesis in hMSC. This offers insight into both how nicotine affects bone remodeling and a therapeutic approach to prevent fracture and osteoporosis in smokers.

Peroxisome proliferator-activated receptor delta agonists attenuated the C-reactive protein-induced pro-inflammation in cardiomyocytes and H9c2 cardiomyoblasts

C-reactive protein (CRP) has emerged as a new marker for cardiovascular diseases. Activation of peroxisome proliferator-activated receptor δ (PPARδ) plays beneficial roles in cardiac disorders. However, the relationship between CRP and PPARδ in cardiac cells remains unclear. This study focused on the underlying molecular mechanisms of CRP and PPARδagonists. Cardiomyocytes and cardiomyoblast cell line (H9c2) were used in different groups: Untreated; 15 μg/ml CRP with or without 1 μM PPARδ agonists (L-165041). CRP increased PPARδ and interleukin-6 expression in cardiomyocytes and H9c2 cardiomyoblasts. NF-κB inducing kinase (NIK) and NF-κB pathway also activated by CRP stimulation. These changes could be inhibited by L-165041 through p38MAPK and c-JNK pathways. However, transfection with siRNA of CD32 CRP receptor did not decrease CRP signaling or reverse the effects of L-165041 in CRP-treated cardiomyocytes and H9c2. Pretreatment with L-165041 attenuated apoptosis induced by hypoxia with or without CRP in H9c2 cardiomyoblasts. CRP up-regulated PPARδ expression in cardiomyocytes and H9c2. L-165041 attenuated CRP-induced pro-inflammatory signaling through p38MAPK and c-JNK in H9c2 cardiomyoblasts. However, PPARδ activation attenuated CRP-induced NF-κB pathway may be independent of CD32. These results may provide new evidence of PPARδ beneficial effects for inflammatory cardiomyopathy.

Peroxisome proliferator-activated receptor delta activation leads to increased transintestinal cholesterol efflux

Peroxisome proliferator-activated receptor delta (PPARdelta) is involved in regulation of energy homeostasis. Activation of PPARdelta markedly increases fecal neutral sterol secretion, the last step in reverse cholesterol transport. This phenomenon can neither be explained by increased hepatobiliary cholesterol secretion, nor by reduced cholesterol absorption. To test the hypothesis that PPARdelta activation leads to stimulation of transintestinal cholesterol efflux (TICE), we quantified it by intestine perfusions in FVB mice treated with PPARdelta agonist GW610742. To exclude the effects on cholesterol absorption, mice were also treated with cholesterol absorption inhibitor ezetimibe or ezetimibe/GW610742. GW601742 treatment had little effect on plasma lipid levels but stimulated both fecal neutral sterol excretion ( approximately 200%) and TICE ( approximately 100%). GW610742 decreased intestinal Npc1l1 expression but had no effect on Abcg5/Abcg8. Interestingly, expression of Rab9 and LIMPII, encoding proteins involved in intracellular cholesterol trafficking, was increased upon PPARdelta activation. Although treatment with ezetimibe alone had no effect on TICE, it reduced the effect of GW610742 on TICE. These data show that activation of PPARdelta stimulates fecal cholesterol excretion in mice, primarily by the two-fold increase in TICE, indicating that this pathway provides an interesting target for the development of drugs aiming at the prevention of atherosclerosis.

Abstract 419: Human ApoB100/CETP Transgenic Mouse is a Useful Animal Model for Evaluation of HDL-C Elevation and Suppression of Atherosclerosis by Peroxisome Proliferator-Activated Receptor Delta Agonist

PPARδ is one of the transcription factors that regulate lipid metabolism. Recently, PPARδ agonists have been reported to induce the elevation of plasma HDL-C levels in obese mice, rhesus monkeys as well as humans, indicating their potentials as a new class of HDL-C raising agent. In addition, anti-atherosclerotic effects of PPARδ agonists were reported in LDLR-KO and ApoE-KO mice. In these mice, however, the lipoprotein profiles are greatly different from those in humans in terms of the deficiency in CETP and ApoB100, and thus the anti-inflammatory effects were regarded as a main anti-atherosclerotic mechanism of PPARδ agonists. It has been reported that human ApoB100/CETP transgenic (hApoB100/CETP-Tg) mice have similar lipoprotein profiles with humans. In this study, we used hApoB100/CETP-Tg mice placed under a western diet for evaluation of GW501516, one of the most potent and selective PPARδ agonists, in order to investigate the linkage between HDL-C elevation and anti-atherosclerotic potency. For evaluation of plasma HDL-C levels, the hApoB100/CETP-Tg mice were orally treated with GW501516 for 1 week and its potency was compared with fenofibrate, a PPARα agonist used in the clinic. For evaluation of the anti-atherosclerotic effect, the mice were orally treated with GW501516 for 18 weeks and atherosclerosis at the aortic valves was determined by cross-sectional lesion analysis. Serum lipoprotein parameters were periodically monitored and lipoprotein profiles were analyzed by FPLC method. Treatment with GW501516 resulted in significant elevation of plasma HDL-C levels with more potency compared to fenofibrate (24% and 15% elevation at 10mg/kg, respectively). Serum apoA-I was also increased by the similar ratio as HDL-C, and the particle size of HDL was not changed, suggesting that the numbers of HDL particle are increased by GW501516. Long term treatment of GW501516 (3 and 10 mg/kg) resulted in dose-dependent suppression of atherosclerosis (42 and 57% inhibition, respectively) with a strong correlation with HDL-C elevation (p&lt;0.001). By using hApoB100/CETP-Tg mice, PPARδ was confirmed as a promising target of anti-atherosclerotic therapy as a new class of HDL-C raising agent.

Pharmacological Regulation of Dyslipoproteinaemia in Insulin Resistant States

Dyslipidaemia is a common and consistent abnormality in insulin resistant subjects with obesity and type 2 diabetes mellitus associated with increased risk of cardiovascular disease. Lipoprotein metabolism is complex and abnormal plasma concentrations can result from alterations in the rates of production and/or catabolism of diverse lipoprotein particles. Our understandings of the dysregulation and therapeutic regulation of lipoprotein transport in insulin resistant states has relied on the application of advances in stable isotope and modelling methods. Dysregulation of lipoprotein metabolism in these circumstances may be caused by a combination of overproduction of VLDL apolipoprotein (apoB) B-100 and VLDL-apoC-III, decreased catabolism of apoB-containing particles, and increased catabolism of HDL apoA-I particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance and accumulation of visceral fat. Several pharmacological treatments, such as statins, fibrates or fish oil can correct the dyslipidaemia by diverse kinetic mechanisms of action, including decreased secretion of apoB and apoC-III, and increased catabolism of apoB, as well as increased secretion and decreased catabolism of apoA-I. Newer agents, including insulin sensitizers, cholesterol absorption inhibitors, CETP inhibitors, peroxisome proliferator-activated receptor-delta agonists and endocannabinoid-1 receptor blockers, have also been shown to improve plasma lipid and lipoprotein abnormalities in insulin resistant states; their mechanisms of action are at present being investigated. Rimonabant is the endocannabinoid receptor blocker shown to decrease cardiometabolic risk in insulin resistant subjects. The complementary mechanisms of action of different agents support the use of combination regimens in treating dyslipoproteinaemia in subjects with central obesity and type 2 diabetes.

Indanylacetic Acid Derivatives Carrying 4-Thiazolyl-phenoxy Tail Groups, a New Class of Potent PPAR α/γ/δ Pan Agonists: Synthesis, Structure−Activity Relationship, and In Vivo Efficacy

Compounds that simultaneously activate the three peroxisome proliferator-activated receptor (PPAR) subtypes alpha, gamma, and delta hold potential to address the adverse metabolic and cardiovascular conditions associated with diabetes and the metabolic syndrome. We recently identified the indanylacetic acid moiety as a well-tunable PPAR agonist head group. Here we report the synthesis and structure-activity relationship (SAR) studies of novel aryl tail group derivatives that led to a new class of potent PPAR pan agonists. While most of the tail group modifications imparted potent PPAR delta agonist activity, improvement of PPAR alpha and gamma activity required the introduction of new heterocyclic substituents that were not known in the PPAR literature. Systematic optimization led to the discovery of 4-thiazolyl-phenyl derivatives with potent PPAR alpha/gamma/delta pan agonistic activity. The lead candidate from this series was found to exhibit excellent ADME properties and superior therapeutic potential compared to known PPAR gamma activating agents by favorably modulating lipid levels in hApoA1 mice and hyperlipidemic hamsters, while normalizing glucose levels in diabetic rodent models.

PPARβ/δ Regulates Paneth Cell Differentiation Via Controlling the Hedgehog Signaling Pathway

All 4 differentiated epithelial cell types found in the intestinal epithelium derive from the intestinal epithelial stem cells present in the crypt unit, in a process whose molecular clues are intensely scrutinized. Peroxisome proliferator-activated receptor beta (PPARbeta) is a nuclear hormone receptor activated by fatty acids and is highly expressed in the digestive tract. However, its function in intestinal epithelium homeostasis is understood poorly. To assess the role of PPARbeta in the small intestinal epithelium, we combined various cellular and molecular approaches in wild-type and PPARbeta-mutant mice. We show that the expression of PPARbeta is particularly remarkable at the bottom of the crypt of the small intestine where Paneth cells reside. These cells, which have an important role in the innate immunity, are strikingly affected in PPARbeta-null mice. We then show that Indian hedgehog (Ihh) is a signal sent by mature Paneth cells to their precursors, negatively regulating their differentiation. Importantly, PPARbeta acts on Paneth cell homeostasis by down-regulating the expression of Ihh, an effect that can be mimicked by cyclopamine, a known inhibitor of the hedgehog signaling pathway. We unraveled the Ihh-dependent regulatory loop that controls mature Paneth cell homeostasis and its modulation by PPARbeta. PPARbeta currently is being assessed as a drug target for metabolic diseases; these results reveal some important clues with respect to the signals controlling epithelial cell fate in the small intestine.

Roles of peroxisome proliferator-activated receptor delta in skeletal muscle function and adaptation.

Peroxisome proliferator-activated receptors mediate the transcriptional effects of fatty acids and fatty acid metabolites and regulate many physiological functions including development and metabolism. The roles of peroxisome proliferator-activated receptor alpha and gamma isotypes have been well established, while the functions of the third member of the family, peroxisome proliferator-activated receptor delta, remained unclear until very recently. This review focuses on the physiological functions of the nuclear receptor and especially on its roles in the control of fatty acid metabolism. We review very recent data demonstrating that peroxisome proliferator-activated receptor delta plays a central role in the regulation of fatty acid oxidation in several tissues, such as skeletal muscle and adipose tissue, and also that the nuclear receptor is involved in cholesterol metabolism. Use of potent and specific peroxisome proliferator-activated receptor delta agonists and appropriate transgenic animal models revealed the importance of this nuclear receptor in regulation of fatty acid catabolism in skeletal muscle and other tissues. It also indicated the potential of peroxisome proliferator-activated receptor delta as a therapeutic target in pathologies such as metabolic syndrome. However, the effects of peroxisome proliferator-activated receptor delta activation in atherosclerosis and the control of cell proliferation remain to be established.