Peroxisome Proliferator-activated Receptor Gamma Antagonist Research Articles

Human Biomonitoring of Environmental Chemicals among Elderly in Wuhan, China: Prioritizing Risks Using EPA's ToxCast Database.

In line with the "healthy aging" principle, we aim to assess the exposure map and health risks of environmental chemicals in the elderly. Blood samples from 918 elderly individuals in Wuhan, China, were analyzed using the combined gas/liquid-mass spectrometry technology to detect levels of 118 environmental chemicals. Cluster analysis identified exposure profiles, while risk indexes and bioanalytical equivalence percentages were calculated using EPA's ToxCast database. The detection rates for 87 compounds exceeded 70%. DEHP, DiBP, naphthalene, phenanthrene, DnBP, pyrene, anthracene, permethrin, fluoranthene, and PFOS showed the highest concentrations. Fat-soluble pollutants varied across lifestyles. In cluster 2, which was characterized by higher concentrations of fat-soluble substances, the proportion of smokers or drinkers was higher than that of nonsmokers or nondrinkers. Pesticides emerged as the most active environmental chemicals in peroxisome proliferator-activated receptor gamma antagonist, thyroid hormone receptor (TR) antagonist, TR agonist, and androgen receptor (AR) agonist activity assays. Additionally, PAEs and polycyclic aromatic hydrocarbons played significant roles as active contaminants for the corresponding targets of AR antagonists and estrogen receptor alpha. We proposed a list of priority pollutants linked to endocrine-disrupting toxic effects in the elderly, which may provide the groundwork for further research into environmental etiology.

Evaluation of the protective effect of losartan in acetaminophen-induced liver and kidney damage in mice

Acetaminophen is widely used among humans as an antipyretic and analgesic. In this study, the protective effect of losartan in hepatotoxicity and nephrotoxicity induced by acetaminophen in mice was investigated owing to its anti-inflammatory and antioxidant effects. An injection of a single dose of 500 mg/kg (i.p.) acetaminophen was administered to induce hepatotoxicity and nephrotoxicity in Groups VI–X. Losartan at doses of 1 mg/kg (Group VII), 3 mg/kg (Group VIII), and 10 mg/kg (Groups III, V, IX, and X) was injected intraperitoneally twice, at 1 and 12 h after the acetaminophen injection. Additionally, a 4 mg/kg dose of GW9662 (peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist) was injected intraperitoneally 30 min before the losartan injections in Groups V and X. At the end of 24 h, the mice were euthanized, and blood, liver, and kidney tissue samples were collected. Levels of AST, ALT, creatinine, and oxidative stress markers including TBARS, SOD, CAT, GPx, TAS, TOS, GSH, and GSSG, along with pro-inflammatory cytokines IL-1β, IL-6, IL-8, IL-10, IL-17, and TNF-α, were measured using ELISA kits. Additionally, a histological evaluation of the tissue samples was performed. Acetaminophen causes increases in the levels of AST, ALT, creatinine, TBARS, TOS, GSSG, IL-1β, IL-6, IL-8, IL-10, IL-17, and TNF-α in serum, liver, and kidney tissue. Meanwhile, it led to a decrease in the levels of SOD, CAT, GPx, TAS, and GSH. Losartan injection reversed oxidative and inflammatory damage induced by acetaminophen. Histopathological changes in liver and kidney tissue were alleviated by losartan. The substance GW9662 increased the protective effect of losartan. In light of all the data obtained from our study, it can be said that losartan has a protective effect on liver and kidney damage induced by acetaminophen due to its antioxidant and anti-inflammatory effects. In terms of the study, losartan was found to be an alternative substance that could protect people from the harmful effects of acetaminophen.

Protective effects of iodine on rat prostate inflammation induced by sex hormones and on the DU145 prostate cancer cell line treated with TNF

Molecular iodine (I2) prevents oxidative stress and prostate hyperplasia induced by hyperandrogenism and reduces cell viability in prostate cancer cell lines. Here, we aimed to evaluate the protective effect of I2 and testosterone (T) on hyperestrogenism-induced prostate inflammation. Additionally, the effects of I2 and/or tumor necrosis factor (TNF) on cell viability and interleukin 6 (IL6) secretion were evaluated in a prostate cancer cell line (DU145). We also investigated whether the effects of I2 on viability are peroxisome proliferator-activated receptor gamma (PPARG)-dependent. Castrated (Cx) rats received pellets of either 17β estradiol (E2) or E2 and T and were treated with I2 (0.05%) in the drinking water for four weeks. The experimental groups were sham, Cx, Cx + E2, Cx + E2+I2, Cx + E2+T, and Cx + E2+T + I2. As expected, inflammation was triggered in the Cx + E2 group (high inflammation score; increase in TNF and transcriptional activity of RELA [nuclear factor-kappa B p65 subunit]), and this effect was diminished in the Cx + E2+T group (medium inflammation score and decrease in TNF). The lowest inflammation score (decrease of TNF and RELA and increase of PPARG) was obtained in the Cx + E2+T + I2 group. In DU145 cells, I2 (400 μM) and TNF (10 ng/ml) additively reduced cell viability, and I2 reduced the production of TNF-stimulated IL6. The PPARG antagonist (GW9662) did not inhibit the effects of I2 on the loss of cell viability. In summary, our data suggest that I2 and T exert a synergistic anti-inflammatory action on the normal prostate, and the interrelationship between I2 and TNF leads to anti-proliferative effects in DU145 cells. PPARG does not seem to participate in the I2-induced cell viability loss in the prostate.

PSVIII-B-14 Peroxisome Proliferator-Activated Receptor Gamma Activation Protects Against Deoxynivalenol-Induced Intestinal Barrier Dysfunction in Jejunal Ipec-J2 Cells

Abstract The role of peroxisome proliferator activated receptor gamma (PPARg) in the regulation of lipid metabolism, adipocyte differentiation and inflammatory response has been well characterized. Besides adipose tissue, PPARg is also highly expressed in the intestine. However, the functional role of PPARg in the regulation of intestinal function still remains poorly understood. In the present study we sought to understand the role of PPARg activation on intestinal barrier function in IPEC-J2 cells exposed (2mM, 24hr) to the mycotoxin, deoxynivalenol (DON). PPARg activation by rosiglitazone and troglitazone dose-dependently increased (P < 0.05) the protein expression of tight junction proteins (TJP), claudin-3 and 4. On the contrary, the protein abundance of claudin-3 and 4 was dose-dependently decreased by PPARg antagonist, T0070907. DON exposure decreased the protein expression of TJP, and also significantly suppressed (P < 0.05) PPARg transcriptional activity. Consistent with the therapeutic benefits of PPARg agonists, pretreatment of cells with PPARg agonists (40 mM) reversed (P < 0.05) the reduction of claudin-3 and 4 induced by DON exposure. Immunofluorescence analysis showed that the decreased membrane presence of claudin-4 and ZO-1 induced by DON was also reversed by troglitazone. Effect of PPARg activation also included partial restoration of transepithelial electrical resistance (TEER) and reduction of FITC-dextran permeability that have been disrupted by DON. However, the protective effects of PPARg agonist against DON exposure was abolished by PPARg antagonist, confirming the importance of PPARg in the observed effects of the agonists. This shows the importance of PPARg activity in the maintenance of intestinal epithelial cells homeostasis and barrier function, especially during periods of metabolic stress induced by the mycotoxin, DON. Therefore, pharmacological and natural bioactive compounds with PPARg agonist activity could be effective in preventing DON-induced gut barrier dysfunction in vivo.

GW9662, a peroxisome proliferator-activated receptor gamma antagonist, attenuates the development of non-alcoholic fatty liver disease

Background and aimsInsulin resistance is among the key risk factors for the development of non-alcoholic fatty liver disease (NAFLD). Recently, it has been reported that GW9662, shown to be a potent peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, may improve insulin sensitivity in settings of type 2 diabetes. Here, we determined the effects of GW9662 on the development of NAFLD and molecular mechanisms involved. MethodsFemale C57BL/6J mice were pair-fed either a liquid control diet (C) or a fat-, fructose- and cholesterol-rich diet (FFC) for 8 weeks while either being treated with GW9662 (1 mg/kg body weight; C+GW9662 and FFC+GW9662) or vehicle (C and FFC) i.p. three times weekly. Indices of liver damage and inflammation, parameters of glucose metabolism and portal endotoxin levels were determined. Lipopolysaccharide (LPS)-challenged J774A.1 cells were treated with 10 μM GW9662. ResultsDespite similar caloric intake the development of NAFLD and insulin resistance were significantly attenuated in FFC+GW9662-treated mice when compared to FFC-fed animals. Bacterial endotoxin levels in portal plasma were almost similarly increased in both FFC-fed groups while expressions of toll-like receptor 4 (Tlr4), myeloid differentiation primary response 88 (Myd88) and interleukin 1 beta (Il1b) as well as nitrite (NO2−) concentration in liver were significantly higher in FFC-fed mice than in FFC+GW9662-treated animals. In J774A.1 cells, treatment with GW9662 significantly attenuated LPS-induced expression of Il1b, interleukin 6 (Il6) and inducible nitric oxide synthase (iNos) as well as NO2− formation. ConclusionIn summary, our data suggest that the PPARγ antagonist GW9662 attenuates the development of a diet-induced NAFLD and that this is associated with a protection against the activation of the TLR4 signaling cascade.

Non-Invasive Characterization of Experimental Bone Metastasis in Obesity Using Multiparametric MRI and PET/CT.

Simple SummaryThe bone marrow microenvironment, particularly adipocytes, plays a pivotal role as growth mediators of disseminated tumor cells in the bone marrow. In this prospective longitudinal study, we used multimodal and multiparametric imaging from magnetic resonance (MRI) and hybrid imaging (positron emission tomography and computed tomography; PET/CT) to non-invasively characterize the pathophysiologic processes of experimental bone metastases in obese and non-obese individuals. Obesity was induced by a high-fat diet (HFD) in rats and mice, resulting in enhanced glucose metabolism and angiogenic activity in metastatic bone lesions, as shown by significantly increased dynamic contrast-enhanced MRI and [18F]fluorodeoxyglucose PET/CT parameters in HFD-fed animals. These results were validated with immunohistochemistry and gene expression analysis. In conclusion, pathophysiological processes can be non-invasively assessed by MRI and PET/CT, opening novel avenues for quantitative assessment of follow-up and monitoring of treatment response in skeletal lesions.The growth of primary tumors and metastases is associated with excess body fat. In bone metastasis formation, the bone marrow microenvironment, and particularly adipocytes, play a pivotal role as growth mediators of disseminated tumor cells in the bone marrow. The aim of the present study is to non-invasively characterize the pathophysiologic processes in experimental bone metastasis resulting from accelerated tumor progression within adipocyte-rich bone marrow using multimodal imaging from magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT). To achieve this, we have employed small animal models after the administration of MDA-MB 231 breast cancer and B16F10 melanoma cells into the bone of nude rats or C57BL/6 mice, respectively. After tumor cell inoculation, ultra-high field MRI and µPET/CT were used to assess functional and metabolic parameters in the bone marrow of control animals (normal diet, ND), following a high-fat diet (HFD), and/or treated with the peroxisome proliferator-activated receptor-gamma (PPARγ) antagonist bisphenol-A-diglycidylether (BADGE), respectively. In the bone marrow of nude rats, dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI), as well as [18F]fluorodeoxyglucose-PET/CT([18F]FDG-PET/CT), was performed 10, 20, and 30 days after tumor cell inoculation, followed by immunohistochemistry. DCE-MRI parameters associated with blood volume, such as area under the curve (AUC), were significantly increased in bone metastases in the HFD group 30 days after tumor cell inoculation as compared to controls (p < 0.05), while the DWI parameter apparent diffusion coefficient (ADC) was not significantly different between the groups. [18F]FDG-PET/CT showed an enhanced glucose metabolism due to increased standardized uptake value (SUV) at day 30 after tumor cell inoculation in animals that received HFD (p < 0.05). BADGE treatment resulted in the inversion of quantitative DCE-MRI and [18F]FDG-PET/CT data, namely a significant decrease in AUC and SUV in HFD-fed animals as compared to ND-fed controls (p < 0.05). Finally, immunohistochemistry and qPCR confirmed the HFD-induced stimulation in vascularization and glucose activity in murine bone metastases. In conclusion, multimodal and multiparametric MRI and [18F]FDG-PET/CT were able to derive quantitative parameters in bone metastases, revealing an increase in vascularization and glucose metabolism following HFD. Thus, non-invasive imaging may serve as a biomarker for assessing the pathophysiology of bone metastasis in obesity, opening novel options for therapy and treatment monitoring by MRI and [18F]FDG-PET/CT.

Interleukin-4 treatment reduces leukemia burden in acute myeloid leukemia.

Interleukin-4 (IL-4) is a signature cytokine pivotal in Type 2helper T cell (Th2) immune response, particularly in allergy and hypersensitivity. Interestingly, IL-4 increases endogenous levels of prostaglandin D2 (PGD2 ) and its metabolites, Δ12 -prostaglandin J2 (Δ12 -PGJ2 ) and 15-deoxy-Δ12,14 -prostaglandin J2 (15d-PGJ2 ), collectively called cyclopentenone PGs (CyPGs). However, the therapeutic role of IL-4 in hematologic malignancies remains unclear. Here, we employed a murine model of acute myeloid leukemia (AML), where human MLL-AF9 fusion oncoprotein was expressed in hematopoietic progenitor cells, to test the effect of IL-4 treatment in vivo. Daily intraperitoneal treatment with IL-4 at 60µg/kg/d significantly alleviated the severity of AML, as seen by decreased leukemia-initiating cells (LICs). The effect of IL-4 was mediated, in part, by the enhanced expression of hematopoietic- PGD2 synthase (H-PGDS) to effect endogenous production of CyPGs, through autocrine and paracrine signaling mechanisms. Similar results were seen with patient-derived AML cells cultured ex vivo with IL-4. Use of GW9662, a peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, suggested endogenous CyPGs-PPARγ axis mediated p53-dependent apoptosis of LICs by IL-4. Taken together, our results reveal a beneficial role of IL-4 treatment in AML suggesting a potential therapeutic regimen worthy of clinical trials in patients with AML.

Betulinic acid decreases lipid accumulation in adipogenesis-induced human mesenchymal stem cells with upregulation of PGC-1α and UCP-1 and post-transcriptional downregulation of adiponectin and leptin secretion.

BackgroundControlling cellular functions, including stem cell growth and differentiation, can be the key for the treatment of metabolic disorders, such as type II diabetes mellitus (T2DM). Previously identified as peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, betulinic acid (BA) may have the capability to control stem cell homeostasis, benefiting T2DM treatment. In this study, the effects of BA on osteogenesis and adipogenesis mechanisms of human mesenchymal stem cells (hMSCs) were investigated.ResultsWe observed that BA increased hMSC osteogenesis by enhancing the alkaline phosphatase activity, calcium deposition, and mRNA expressions of osteogenic markers, namely, runt-related transcription factor 2, osteocalcin, and osteopontin. In addition, BA decreased hMSC adipogenesis with the decrease in glycerol-3-phosphate dehydrogenase activity, reduced intracellular lipid accumulations, down-regulated CCAAT-enhancer-binding protein alpha, and suppressed post-transcriptional adiponectin and leptin secretion. BA increased the brown adipocyte characteristics with the increase in the ratio of small lipid droplets and glucose uptake. Furthermore, the mRNA expressions of brown adipocyte markers, namely, PPARγ coactivator one alpha, uncoupling protein 1, and interleukin-6 increased.ConclusionsOur results uncovered the mechanisms of how BA improved glucose and lipid metabolisms by decreasing white adipogenesis and increasing brown adipogenesis. Altogether, BA may be used for balancing glucose metabolisms without the potential side effects on bone loss or weight gain.

Bitter receptor TAS2R138 facilitates lipid droplet degradation in neutrophils during Pseudomonas aeruginosa infection

Bitter receptors function primarily in sensing taste, but may also have other functions, such as detecting pathogenic organisms due to their agile response to foreign objects. The mouse taste receptor type-2 member 138 (TAS2R138) is a member of the G-protein-coupled bitter receptor family, which is not only found in the tongue and nasal cavity, but also widely distributed in other organs, such as the respiratory tract, gut, and lungs. Despite its diverse functions, the role of TAS2R138 in host defense against bacterial infection is largely unknown. Here, we show that TAS2R138 facilitates the degradation of lipid droplets (LDs) in neutrophils during Pseudomonas aeruginosa infection through competitive binding with PPARG (peroxisome proliferator-activated receptor gamma) antagonist: N-(3-oxododecanoyl)-l-homoserine lactone (AHL-12), which coincidently is a virulence-bound signal produced by this bacterium (P. aeruginosa). The released PPARG then migrates from nuclei to the cytoplasm to accelerate the degradation of LDs by binding PLIN2 (perilipin-2). Subsequently, the TAS2R138–AHL-12 complex targets LDs to augment their degradation, and thereby facilitating the clearance of AHL-12 in neutrophils to maintain homeostasis in the local environment. These findings reveal a crucial role for TAS2R138 in neutrophil-mediated host immunity against P. aeruginosa infection.

Perfluorobutanesulfonic acid (PFBS) induces fat accumulation in HepG2 human hepatoma

Per- and poly-fluoroalkyl substances, especially perfluorooctanesulfonic acid (PFOS), have been extensively used for over 50 years. A growing body of evidence has emerged demonstrating the potential adverse effects of these substances, including its effect on the development of non-alcoholic fatty liver disease, as one of the most prevalent chronic liver diseases. Nonetheless, there is no report of effects of perfluorobutanesulfonic acid (PFBS), the major replacement for PFOS, on non-alcoholic fatty liver disease. Therefore, the effects of PFBS exposure on fat accumulation in a human hepatoma cell line were examined. Cells were exposed to PFBS with or without 300 μmol/L fatty acid mixture (oleic acid–palmitic acid, 2:1) conjugated by bovine serum albumin as an inducer of steatosis for 48 h. PFBS at 200 μmol/L significantly increased the triglyceride level in the presence of fatty acid compared to the control, but not without fatty acid, which was abolished by a specific peroxisome proliferator-activated receptor gamma antagonist. PFBS upregulated key genes controlling lipogenesis and fatty acid uptake. PFBS treatment also promoted the production of reactive oxygen species, an endoplasmic reticulum stress marker and cytosolic calcium. In conclusion, PFBS increased fat accumulation, in part, via peroxisome proliferator-activated receptor gamma-mediated pathway in hepatoma cells. Abbreviations: ACC: acetyl-CoA carboxylase; CD36: cluster of differentiation 36; CHOP: CCAAT/enhancer-binding homologous protein; CPT1α: carnitine palmitoyltransferase 1α; DDIT3: DNA damage-inducible transcript 3; DGAT2: diacylglycerol O-acyltransferase 2; ER: endoplasmic reticulum; FA: fatty acid; FAS: fatty acid synthase; NAFLD: nonalcoholic fatty liver disease; NF-κB: nuclear factor kappa B; PFAS: per- and polyfluoroalkyl substances; PFBS: perfluorobutanesulfonic acid; PFOS: perfluorooctanesulfonic acid; PPAR: peroxisome proliferator-activated receptor; ROS: reactive oxygen species; SREBP1: sterol regulatory element-binding protein 1; TG: triglyceride; TNF-α: tumor necrosis factor alpha; UPR: unfolded protein response

FRI084 - Gw9662, a peroxisome proliferator-activated receptor gamma antagonist, attenuates the development of non-alcoholic fatty liver disease

FRI084 - Gw9662, a peroxisome proliferator-activated receptor gamma antagonist, attenuates the development of non-alcoholic fatty liver disease

The PPAR-\u03b3 antagonist T007 inhibits RANKL-induced osteoclastogenesis and counteracts OVX-induced bone loss in mice

BackgroundOsteoclasts are key determinant cellular components implicated in the development and progression of disorders driven by bone damage. Herein, we studied the upshot of T007, an antagonist of peroxisome proliferator-activated receptor-gamma (PPARγ), on osteoclastogenesis using cell and animal models.ResultsThe in vitro assays revealed that T007 hindered the osteoclastogenesis caused by the treatment with the receptor activator of nuclear factor-κB ligand (RANKL) through inhibiting the levels of PPARγ in cells. The PPARγ siRNA partially reproduced the inhibitory action of T007. The opposite findings were produced after PPARγ overexpression. Furthermore, T007 prevented from bone loss in a mouse model of osteoporosis induced by ovariectomy (OVX). These findings implied that T007 is a potential efficient drug for the prophylaxis and cure of osteoclast-related disorders.ConclusionsTaken together, our findings demonstrated that T007 impedes osteoclastogenesis and will be useful for the therapy of bone related diseases, essentially osteoporosis.

Decitabine assists umbilical cord-derived mesenchymal stem cells in improving glucose homeostasis by modulating macrophage polarization in type 2 diabetic mice

BackgroundMesenchymal stem cells (MSCs) have emerged as a promising therapy for type 2 diabetes (T2D). Mechanistic researches demonstrate that the anti-diabetic effect of MSCs is partially mediated by eliciting macrophages into an anti-inflammatory phenotype thus alleviating insulin resistance. However, single MSC infusion is insufficient to ameliorate sustained hyperglycemia or normalize blood glucose levels. In this study, we used decitabine (DAC), which is involved in the regulation of macrophage polarization, to test whether MSCs combined with decitabine can prolong and enhance the anti-diabetic effect in T2D mice.MethodsHigh-fat diet (HFD) and streptozocin (STZ) were given to induce T2D mouse model. Successfully induced T2D mice were randomly divided into four groups: T2D group, MSC group, DAC group, and MSC + DAC group. Blood glucose was monitored, and glucose tolerance and insulin sensitivity were evaluated during the entire analysis period. Epididymal fat was extracted for analysis of macrophage phenotype and inflammation in adipose tissue. In vitro, we examined the effect of MSC + DAC on macrophage polarization in bone marrow-derived macrophages (BMDMs) and explore the possible mechanism.ResultsMSC infusion effectively improved insulin sensitivity and glucose homeostasis in T2D mice within 1 week, whereas combination therapy of MSCs + DAC extended the anti-diabetic effects of MSCs from 1 to 4 weeks (the end of the observation). Correspondingly, more M2 macrophages in adipose tissue were observed in the combination therapy group over the entire study period. In vitro, compared with the MSC group, MSCs combined with decitabine more effectively polarized M1 macrophages to M2 macrophages. Further analysis showed that the effect of MSC + DAC on macrophage polarization was largely abrogated by the peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662.ConclusionsOur data suggest that MSCs combined with decitabine can more effectively alleviate insulin resistance and prolong and enhance the anti-diabetic effect of MSCs in T2D mice in part by prompting M2 polarization in a PPARγ-dependent manner. Thus, decitabine may be an applicable addition to MSCs for diabetes therapy.Graphic UC-MSCs combined with decitabine activate the IL4R/STAT6/STAT3/PPARγ axis to further promote M2 macrophage polarization in adipose tissue, reduce inflammation, improve insulin sensitivity, and lead to better glucose metabolism and long-term hypoglycemic effects

Increased Bone Marrow-Specific Adipogenesis by Clofazimine Causes Impaired Fracture Healing, Osteopenia, and Osteonecrosis Without Extraskeletal Effects in Rats.

Mycobacterium leprae infection causes bone lesions and osteoporosis, however, the effect of antileprosy drugs on the bone is unknown. We, therefore, set out to address it by investigating osteogenic differentiation from bone marrow (BM)-derived mesenchymal stem cells (MSCs). Out of 7 antileprosy drugs, only clofazimine (CFZ) reduced MSCs viability (IC50 ∼ 1 μM) and their osteogenic differentiation but increased adipogenic differentiation on a par with rosiglitazone, and this effect was blocked by a peroxisome proliferator-activated receptor gamma antagonist, GW9662. CFZ also decreased osteoblast viability and resulted in impaired bone regeneration in a rat femur osteotomy model at one-third human drug dose owing to increased callus adipogenesis as GW9662 prevented this effect. CFZ treatment decreased BM MSC population and homing of MSC to osteotomy site despite drug levels in BM being much less than its in vitro IC50 value. In adult rats, CFZ caused osteopenia in long bones marked by suppressed osteoblast function due to enhanced adipogenesis and increased osteoclast functions. A robust increase in marrow adipose tissue (MAT) by CFZ did not alter the hematologic parameters but likely reduced BM vascular bed leading to osteonecrosis (ON) characterized by empty osteocyte lacunae. However, CFZ had no effect on visceral fat content and was not associated with any metabolic and hematologic changes. Levels of unsaturated fatty acids in MAT were higher than saturated fatty acids and CFZ further increased the former. From these data, we conclude that CFZ has adverse skeletal effects and could be used for creating a rodent ON model devoid of extraskeletal effects.

Pioglitazone improves visceral sensation and colonic permeability in a rat model of irritable bowel syndrome

Visceral hypersensitivity and impaired gut barrier with minor inflammation are considered to play an important role in the pathophysiology of irritable bowel syndrome (IBS). Since pioglitazone is known to have anti-inflammatory property, we hypothesized that pioglitazone is beneficial for treating IBS. In this study, the effect was tested in rat IBS models such as lipopolysaccharide or repeated water avoidance stress-induced visceral allodynia and increased colonic permeability. Pioglitazone blocked these visceral changes, and GW9662, a peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist fully reversed the effect by pioglitazone. These results suggest that PPAR-γ activation by pioglitazone may be useful for IBS treatment.

Lysophospholipid-Related Diseases and PPARγ Signaling Pathway.

The nuclear receptor superfamily includes ligand-inducible transcription factors that play diverse roles in cell metabolism and are associated with pathologies such as cardiovascular diseases. Lysophosphatidic acid (LPA) belongs to a family of lipid mediators. LPA and its naturally occurring analogues interact with G protein-coupled receptors on the cell surface and an intracellular nuclear hormone receptor. In addition, several enzymes that utilize LPA as a substrate or generate it as a product are under its regulatory control. Recent studies have demonstrated that the endogenously produced peroxisome proliferator-activated receptor gamma (PPARγ) antagonist cyclic phosphatidic acid (cPA), which is structurally similar to LPA, inhibits cancer cell invasion and metastasis in vitro and in vivo. We recently observed that cPA negatively regulates PPARγ function by stabilizing the binding of the co-repressor protein, a silencing mediator of retinoic acid, and the thyroid hormone receptor. We also showed that cPA prevents neointima formation, adipocyte differentiation, lipid accumulation, and upregulation of PPARγ target gene transcription. The present review discusses the arbitrary aspects of the physiological and pathophysiological actions of lysophospholipids in vascular and nervous system biology.

Design and Synthesis of Peroxisome Proliferator-activated Receptor (PPAR) Gamma Antagonists Based on the Principle of Operation of Nuclear Receptor I.

Peroxisome proliferator-activated receptor γ (PPARγ) antagonist is a molecular target to create drug for the treatment of not only type 2 diabetes and obesity, but also cancer. However, few rational drug design strategies and concepts are available. Here, we utilized the nuclear receptor helix12-folding inhibition hypothesis, in combination with structural biology data of our PPARγ agonist (5) complexed with the PPARγ ligand-binding domain. We found a potent phenylalkynyl amide-type PPARγ antagonist 18i, based on pinpoint structural modification of the acidic head part of 5. Although 18i exhibited potent PPARγ antagonistic activity, it retained very weak, but distinct PPARγ agonistic activity. We then modified the distal benzene ring of 18i, to delete the residual PPARγ agonistic activity. Introduction of a chlorine atom at the 2-position of the distal benzene ring afforded 18p, which exhibited potent, PPARγ-selective antagonistic activity without any detectable PPARγ agonistic activity. We realized that 18p stabilized the corepressor-PPARγ complex and suppressed basal PPARγ activity. This compound showed potent anti-adipogenesis activity at the cellular level.

Expression of CYP4V2 in human THP1 macrophages and its transcriptional regulation by peroxisome proliferator-activated receptor gamma

Because macrophages respond to a variety of pathological and pharmacological reagents, understanding the role of P450s in macrophages is important for therapeutic intervention. There has been a lack of research on CYP4 in macrophages, but fatty acid accumulation and lipid trafficking in macrophages have been suggested to be a main cause of atherosclerosis. All human CYP4 genes (n=12) were screened in THP1 macrophages by gene-specific reverse transcriptase-polymerase chain reaction (RT-PCR). Only CYP4V2 exhibited strong expression of both mRNA and protein. Expression levels of both CYP4V2 mRNA and protein were significantly reduced after treatment with peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662. However, the expression levels of CYP4V2 were not changed by PPARα antagonist (GW6471) and liver X receptor alpha antagonist (22-S hydroxycholesterol). A metabolite of the CYP4V2 enzyme, 12-hydroxydodecanoic acid, was detected in THP1 macrophages, and this metabolite was significantly decreased after treatment with the PPARγ inhibitor GW9662 (>80% decreased, p<0.05). In summary, fatty acid metabolizing protein CYP4V2 was identified in human THP1 macrophages, and its expression was regulated by PPARγ. Further study is required to understand the role of CYP4V2 with regard to fat accumulation in the activated macrophage and atherosclerotic plaque development.

PER1 prevents excessive innate immune response during endotoxin-induced liver injury through regulation of macrophage recruitment in mice.

The severity of acute liver failure (ALF) induced by bacterial lipopolysaccharide (LPS) is associated with the hepatic innate immune response. The core circadian molecular clock modulates the innate immune response by controlling rhythmic pathogen recognition by the innate immune system and daily variations in cytokine gene expression. However, the molecular link between circadian genes and the innate immune system has remained unclear. Here, we showed that mice lacking the clock gene Per1 (Period1) are more susceptible to LPS/d-galactosamine (LPS/GalN)-induced macrophage-dependent ALF compared with wild-type (WT) mice. Per1 deletion caused a remarkable increase in the number of Kupffer cells (KCs) in the liver, resulting in an elevation of the levels of pro-inflammatory cytokines after LPS treatment. Loss of Per1 had no effect on the proliferation or apoptosis of macrophages; however, it enhanced the recruitment of macrophages, which was associated with an increase in CC chemokine receptor 2 (Ccr2) expression levels in monocytes/macrophages. Deletion of Ccr2 rescued d-GalN/LPS-induced liver injury in Per1−/− mice. We demonstrated that the upregulation of Ccr2 expression by Per1 deletion could be reversed by the synthetic peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist GW9662. Further analysis indicated that PER1 binds to PPAR-γ on the Ccr2 promoter and enhanced the inhibitory effect of PPAR-γ on Ccr2 expression. These results reveal that Per1 reduces hepatic macrophage recruitment through interaction with PPAR-γ and prevents an excessive innate immune response in endotoxin-induced liver injury.

Abstract 11691: Atorvastatin Reverses Impaired Voltage-gated K + Channels-mediated Coronary Vasodilation By Upregulating PPARγ In Diabetes (Best of Basic Science Abstract)

Aims: Voltage-gated K + (K v ) channels in vascular smooth muscle cells (VSMCs) play an important role in the regulation of coronary microcirculation. Atorvastatin (ATV) has shown some beneficial effects on vascular function, but the effect of ATV on K v channels-mediated coronary vasodilation remains unknown. The present study was designed to investigate the role of ATV in improving K v channels-mediated coronary dilator function in diabetes and the underlying mechanisms. Methods: Isolated VSMCs were incubated in normal or high glucose medium plus a different dose of ATV for 24 h at 37 o C. Patch-clamp recording and molecular biological techniques were used to assess the function and expression of K v channels. Control or type 2 diabetic rats were treated with ATV (50 mg/kg daily) by oral gavage for 10 weeks. Vasodilation of isolated rat coronary arteries was measured using a pressurized myograph. GW9662, the peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, was used to determine whether the mechanism of ATV-improved K v channel function can be explained by upregulation of PPARγ pathway. Results: Patch-clamp analysis revealed that high glucose reduced K v current density by 58.7 ± 4.6%, which was accompanied by a downregulation of K v 1.2 and K v 1.5 expression. Treatment with ATV reversed the inhibitory effect of high glucose on K v current density in a dose-dependent manner (1 μmol/L, 15.0 ± 2.6%; 10 μmol/L, 49.1 ± 3.8%; 100 μmol/L, 69.9 ± 4.8%; P &lt; 0.05). In addition, ATV restored high glucose-induced downregulation of K v channel protein expression, and the difference was significant in both 10 μmol/L and 100 μmol/L groups. For in vivo study, K v channels-mediated coronary vasodilation was decreased in diabetic rats, compared with controls (9.1 ± 1.3 vs. 36.7 ± 1.4%, P &lt; 0.05), whereas this decrease was partly corrected by ATV (25.0 ± 2.8 vs. 9.1 ± 1.3%, P &lt; 0.05). Treatment with ATV prominently increased protein expression of PPARγ both in vitro and in vivo . The effect of ATV in regulating K v channels and K v channels-mediated vasodilation was markedly blunted by GW9662. Conclusions: In conclusion, treatment with ATV activates PPARγ pathway and preserves K v channel activity in VSMCs, thus providing improvement of coronary dilator function in diabetic rats.