Activation Of Peroxisome Proliferator-activated Receptor-γ Research Articles

Curcumin inhibits APOE4-induced injury by activating peroxisome proliferator-activated receptor-γ (PPARγ) in SH-SY5Y cells.

Objective(s):The human apolipoprotein E4 (APOE4) is associated with various brain injuries and neurodegenerative changes. Curcumin is an active ingredient isolated from the root of turmeric and is believed to have therapeutic effects on neurodegenerative diseases. The aim of this study was to investigate the effects of curcumin on APOE4-induced neurological damage and explore its molecular mechanisms.Materials and Methods:SH-SY5Y cells were pretreated with curcumin for 24 hr and transfected with human APOE4 gene using Lipofectamine 2000. Then, the effect of curcumin on the transfected cells was detected by ELISA, immunofluorescence staining and Western blot.Results:The production or expression of proinflammatory cytokines and proteins, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was significantly increased in SH-SY5Y cells transfected with APOE4, and curcumin inhibited APOE4-induced cellular inflammatory damage. Western blot analysis showed that, after transfection with APOE4, the expression of total nuclear factor kappa B (NF-κB) p65 and p-NF-κB p65 in the nucleus was increased, and curcumin inhibited the nuclear translocation of p65. The overexpression of APOE4 inhibited the expression of peroxisome proliferator-activated receptor-γ (PPARγ), whereas curcumin reversed and increased the expression of PPARγ protein. Down-regulating PPAR-γ with the inhibitor GW9662 and the shPPARγ gene confirmed that the NF-κB signaling pathway was inhibited by PPARγ. Conclusion:This study suggests that APOE4 overexpression can induce cellular inflammatory damage, and pretreatment of curcumin could exert an anti-inflammatory effect by upregulating the expression of PPARγ to inhibit the activation of NF-κB signaling pathway.

Ischemia reperfusion-induced metastasis is resistant to PPARγ agonist pioglitazone in a murine model of colon cancer

Ischemia reperfusion injury (IRI) during liver-metastasis resection for treatment of colon cancer may increase the risk of further metastasis. Peroxisome proliferator-activated receptor-γ (PPARγ) activation has been observed to exert a protective effect against IRI and IRI-induced metastasis of hepatocellular carcinoma. The present study aimed to investigate the effect of the PPARγ agonist pioglitazone on tumor metastasis and liver injury following IRI in a mouse model of colon cancer. Pioglitazone (30 mg/kg weight) was administered orally 1.5 h before and 2 h after the initiation of ischemia and was orally administrated daily to mice from day 0–21. SL4-cancer cells expressing red fluorescent protein (SL4-RFP) (1 × 106) were injected into the spleen. Fifteen minutes after injection, the hepatoduodenal ligament was clamped with a vessel clip, and released 5 min later. Liver, blood and tumor samples were taken from mice in order to determine if inflammation was induced by IRI. The effect of pioglitazone on liver metastasis was assessed. Furthermore, the effect of pioglitazone to control the inflammatory response during IRI progression was examined. Liver metastasis along with MMP-9 activation and the production of inflammatory cytokines were resistant to pioglitazone. Our results indicate that liver metastasis and associated inflammation in mice were resistant to pioglitazone.

In vitro dual-target activities and in vivo antidiabetic effect of 3-hydroxy-N-(p-hydroxy-phenethyl) phthalimide in high-fat diet and streptozotocin-induced diabetic golden hamsters

The 3-hydroxy-N-(p-hydroxy-phenethyl) phthalimide (HNHP), which showed in vitro peroxisome proliferator-activated receptor-γ (PPAR-γ) activation and in vivo anti-inflammatory effect in our previous study, was speculated to be a dual-target lead compound because similar structures exhibited α-glucosidase inhibitory activities. To investigate the dual targeting potential, molecular docking of HNHP was performed targeting on PPAR-γ and α-glucosidase, and HNHP was found to bind with dual targets in the known active sites with relatively high affinities. The in vitro α-glucosidase inhibitory evaluation showed that HNHP inhibited the enzyme (IC50 = 0.669 µM) better than acarbose (IC50 = 49.133 µM). For in vivo antidiabetic activity study, type 2 diabetes mellitus was induced by high-fat diet (20%) and streptozotocin (30 mg/kg) in golden hamsters. The diabetic hamsters were administered with different doses (1, 2, 4 mg/kg/day) of HNHP and rosiglitazone (1 mg/kg/day, positive control) for consecutive 14 days, respectively. Compared with rosiglitazone, HNHP significantly increased the insulin sensitivity, while the fasting blood glucose, glycated hemoglobin Alc, urine sugar, body weight, food/water intake, and lipid profile of media-dose (2 mg/kg/day) group golden hamsters were significantly normalized. Furthermore, pathological investigation found that the media-dose of HNHP showed the best protection on pancreatic tissue. These findings indicated that the PPAR-γ activator HNHP possessed in vitro α-glucosidase inhibitory and in vivo antidiabetic activities. Thereby, HNHP would serve as a new dual-target optimization lead.

Role of Gut Microbiome on Metabolic Disorders

Microbiome that reside in the human gut are key contributors to host metabolism and are considered potential sources of novel therapeutics in metabolic disorders. This review discusses the role of gut microbiome in the pathogenesis of obesity, type 2 diabetes mellitus (T2DM), chronic kidney disease and cardiovascular disease. Gut microbiome remains quite stable, although changes take place between birth and adulthood due to external influences, such as diet, disease and environment. Understanding these changes is important to predict diseases and develop therapies. In gut heamostasis, Gut microbiome converts high fibres intake into short-chain fatty acids like butyrate, propionate and acetate which normalize intestinal permeability and alter de novo lipogenesis and gluconeogenesis through reduction of free fatty acid production by visceral adipose tissue. This effect contributes to reduce food intake and to improve glucose metabolism. Propionate can also bind to G protein coupled receptors (GPR)-43 expressed on lymphocytes in order to maintain appropriate immune defence. Butyrate activates peroxisome proliferator-activated receptor-γ (PPAR-γ) leading to beta-oxidation and oxygen consumption, a phenomenon contributing to maintain anaerobic condition in the gut lumen. In contrast, diets most especially western diet consisting among others of high fat and high salt content has been reported to cause gut dysbiosis. This alteration of gut microbiome result to chronic bacterial translocation and increased intestinal permeability that can drive a systemic inflammation leading to macrophage influx into visceral adipose tissue, activation of hepatic kuffer cells and insulin resistance in type 2 diabetes. This effect contributes to lower mucus thickness, decrease butyrate and propionate producing bacteria, L-cells secrete less gut peptides, lack of PPAR-γ activation lead to higher oxygen available for the microbiome at the proximity of the mucosa and increases the proliferation of Enterobacteriaceae with commensurate increase in opportunistic pathogens. However, Gut microbiome are major biomarker for early prognosis of diabetes and other metabolic disorders.

P0721PPAR-GAMMA ACTIVATION INHIBITS TGF-BETA INDUCED RENAL COMPLEMENT AND GALECTIN-3 EXPRESSION IN VIVO AND IN VITRO

Abstract Background and Aims Reduced peroxisome proliferator-activated receptor-γ (PPARγ) activity has been observed in chronic kidney disease and fibrosis. We have recently shown that the PPARγ agonist pioglitazone dampens TGF-β induced renal pro-fibrotic transcription factors in vivo. Several studies have shown that renal complement expression is associated with fibrosis, yet the role of galectin-3 (Lgals3) remains controversial. However, the effect of PPARγ agonists on renal complement (C3, C4b) and Lgals3 expression has not been studied. We investigated how pioglitazone treatment affects TGF-β–driven renal inflammatory molecule expression in transgenic mice and in primary tubular epithelial cell (PTEC) culture. Method Ten weeks-old male C57Bl6 control (CTL) and TGF-β transgenic mice (with elevated circulating TGF-β1 level) were divided in two sets. The first set of mice received regular chow (CTL and TGFβ, n=4/group). The second set of mice were treated orally with pioglitazone (20mg/kg/day) for 5 weeks (CTL+Pio and TGFβ+Pio, n=5/group), when the kidneys were analyzed for mRNA and protein expression. PTEC were isolated from 4-weels old CTL mouse kidneys using graded sieving and characterized by immunoblot. Isolated cells were maintained in DMEM/F12 medium supplemented with 2% FBS and insulin/transferrin/selenium, and cells of passage 4-6 were used in triplicate for the experiments. Cells were treated for 24h with 10 ng/ml TGF-β and/or 5 µM pioglitazone, then mRNA expression levels were assessed. Statistical significance was verified using Mann-Whitney test. Results TGFβ kidneys depicted 13-fold and 4-fold overexpression of C3 and C4b mRNA (p<0.05), respectively, accompanied by a 1.7-fold Lgals3 expression (p<0.05). Oral treatment with the PPARγ agonist pioglitazone inhibited the TGF-β1 induced overexpression of C3, C4b, Lgals3, as well as IL-6 and CCL2 (MCP-1) mRNA (p<0.01). This was accompanied by reduced alfa-SMA (Actca2) and fibronectin mRNA expression. Renal Lgals3 showed significant correlation with alfa-SMA expression (p<0.01, see Figure). PTEC treated with TGF-β also depicted increased C3aR, alfa-SMA and collagen-1 mRNA expression by 1.7-fold, 2-fold and 2.1-fold, respectively (p<0.01), that were reduced to control levels by pioglitazone treatment (p<0.05). Conclusion Our data indicate that PPARγ activation exert strong anti-inflammatory effects in the renal tubular epithelial cells, implicating its possible therapeutic benefit by attenuating renal EMT and fibrosis in CKD patients.

Chemical Structure-Related Adipogenic Effects of Tetrabromobisphenol A and Its Analogues on 3T3-L1 Preadipocytes.

Tetrabromobisphenol A (TBBPA), the most widely used brominated flame retardant, is reported to potentially possess risks in inducing obesity or obesity-related metabolic diseases. Considering the increasing environmental contamination of TBBPA analogues and their high structural similarities to the parent compound, whether they could influence adipogenesis or not remains to be elucidated. In this study, two of the most prevalent TBBPA derivatives [i.e., TBBPA bis(allyl ether) (TBBPA-BAE) and TBBPA bis(2,3-dibromopropyl ether) (TBBPA-BDBPE)] and their byproducts [i.e., TBBPA mono(allyl ether) (TBBPA-MAE) and TBBPA mono(2,3-dibromopropyl ether) (TBBPA-MDBPE)], together with TBBPA, were screened for their capacities in activating peroxisome proliferator-activated receptor-γ (PPARγ) and glucocorticoid receptor (GR), the key nuclear receptors involved in adipogenesis, and their structure-related effects on differentiation of 3T3-L1 preadipocytes were explored. The results indicated that the binding affinities of TBBPA and its analogues for the PPARγ ligand-binding domain (PPARγ-LBD) and GR, as well as their effects on PPARγ transactivation, followed the order of TBBPA > TBBPA-MAE > TBBPA-MDBPE > TBBPA-BAE, TBBPA-BDBPE. Nevertheless, TBBPA-MAE and TBBPA-MDBPE showed higher potentials in promoting adipogenesis in 3T3-L1 cells than did TBBPA, as evidenced by intracellular triglyceride contents and adipogenic biomarkers at both protein and transcriptional levels. The etherified group at position 4 of TBBPA phenolic rings was crucial in chemical-induced adipogenic effects, which was related with the recruitment of PPARγ and GR-mediated networks and some other unidentified signaling pathways. The findings on the disturbance of TBBPA analogues on adipogenesis revealed their potential risk in causing obesity and other lipid metabolism-related human health concerns.

EFFECTS OF TELMISARTAN ON PLASMA INTERLEUKIN-6 AND C-REACTIVE PROTEIN LEVELS IN MONOSODIUM GLUTAMATE-INDUCED OBESITY IN WISTAR ALBINO RATS

Objectives: The objectives of this study were to evaluate the effects of telmisartan on plasma interleukin (IL)-6 and C-reactive protein (CRP) levels in monosodium glutamate (MSG)-induced obesity in Wistar albino rats.
 Methods: MSG at the dose of 500 mg/kg body weight is dissolved in distilled water and administered for 22 days. On the 9th day, telmisartan 7.5 mg/kg body weight is administered. After completion of experiment, body weight and biochemical parameters such as plasma IL-6 and CRP levels are measured using enzyme-linked immunosorbent assay.
 Results: Telmisartan significantly decreased plasma IL-6 and CRP levels in MSG-treated obese rats.
 Conclusion: Telmisartan, probably through its peroxisome proliferator-activated receptor-γ agonistic activity, produces significant anti-obesity effects in rats and may help in treating obese patients with metabolic syndrome.

Alpinumisoflavone suppresses human Glioblastoma cell growth and induces cell cycle arrest through activating peroxisome proliferator-activated receptor-γ.

As a common subtype of malignant gliomas, glioblastoma multiforme (GBM) is associated with poor prognosis. This study is aimed to examine the anticancer activities of alpinumisoflavone (AIF) and its underlying mechanisms. Our results demonstrated that AIF inhibited the proliferation of GBM cells (U373 and T98G) in a time and dose-dependent manner. In addition, flow cytometry analysis not only confirmed AIF arrested cell cycle at the G0/G1 phase but also the induced apoptosis of U373 and T98G cells. Western blotting also confirmed that AIF altered the expression levels of cell cycle-related proteins. Further mechanism studies revealed that AIF inhibited cell proliferation, induced G0/G1 phase arrest and induced apoptosis of U373 and T98G cells through activating PPARγ, as evidenced by the fact that GW9662 (PPARγ inhibitor) could effectively reverse the effects of AIF on U373 and T98G cells. Furthermore, the in vivo study also revealed that AIF suppressed tumor growth and caused cell cycle arrest. Collectively, these results highlighted the potential use of AIF in the treatment of GBM.

Rosiglitazone ameliorates tissue plasminogen activator‐induced brain hemorrhage after stroke

ObjectiveDelayed thrombolytic therapy with recombinant tissue plasminogen activator (tPA) may exacerbate blood‐brain barrier (BBB) breakdown after ischemic stroke and lead to catastrophic hemorrhagic transformation (HT). Rosiglitazone(RSG), a widely used antidiabetic drug that activates peroxisome proliferator‐activated receptor‐γ (PPAR‐γ), has been shown to protect against cerebral ischemia through promoting poststroke microglial polarization toward the beneficial anti‐inflammatory phenotype. However, whether RSG can alleviate HT after delayed tPA treatment remains unknown. In this study, we sort to examine the role of RSG on tPA‐induced HT after stroke.Methods and resultsWe used the murine suture middle cerebral artery occlusion (MCAO) models of stroke followed by delayed administration of tPA (10 mg/kg, 2 hours after suture occlusion) to investigate the therapeutic potential of RSG against tPA‐induced HT. When RSG(6 mg/kg) was intraperitoneally administered 1 hour before MCAO in tPA‐treated MCAO mice, HT in the ischemic territory was significantly attenuated 1 day after stroke. In the tPA‐treated MCAO mice, we found RSG significantly mitigated BBB disruption and hemorrhage development compared to tPA‐alone‐treated stroke mice. Using flow cytometry and immunostaining, we confirmed that the expression of CD206 was significantly upregulated while the expression of iNOS was down‐regulated in microglia of the RSG‐treated mice. We further found that the expression of Arg‐1 was also upregulated in those tPA and RSG‐treated stroke mice and the protection against tPA‐induced HT and BBB disruption in these mice were abolished in the presence of PPAR‐γ antagonist GW9662 (4 mg/kg, 1 hour before dMCAO through intraperitoneal injection).ConclusionsRSG treatment protects against BBB damage and ameliorates HT in delayed tPA‐treated stroke mice by activating PPAR‐γ and favoring microglial polarization toward anti‐inflammatory phenotype.

Immunometabolic modulation of retinal inflammation by CD36 ligand

In subretinal inflammation, activated mononuclear phagocytes (MP) play a key role in the progression of retinopathies. Little is known about the mechanism involved in the loss of photoreceptors leading to vision impairment. Studying retinal damage induced by photo-oxidative stress, we observed that cluster of differentiation 36 (CD36)-deficient mice featured less subretinal MP accumulation and attenuated photoreceptor degeneration. Moreover, treatment with a CD36-selective azapeptide ligand (MPE-001) reduced subretinal activated MP accumulation in wild type mice and preserved photoreceptor layers and function as assessed by electroretinography in a CD36-dependent manner. The azapeptide modulated the transcriptome of subretinal activated MP by reducing pro-inflammatory markers. In isolated MP, MPE-001 induced dissociation of the CD36-Toll-like receptor 2 (TLR2) oligomeric complex, decreasing nuclear factor-kappa B (NF-κB) and NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. In addition, MPE-001 caused an aerobic metabolic shift in activated MP, involving peroxisome proliferator-activated receptor-γ (PPAR-γ) activation, which in turn mitigated inflammation. Accordingly, PPAR-γ inhibition blocked the cytoprotective effect of MPE-001 on photoreceptor apoptosis elicited by activated MP. By altering activated MP metabolism, MPE-001 decreased immune responses to alleviate subsequent inflammation-dependent neuronal injury characteristic of various vision-threatening retinal disorders.

Ginsenoside Rb1 ameliorates CKD-associated vascular calcification by inhibiting the Wnt/β-catenin pathway.

Vascular calcification (VC) is a pathological process underpinning major cardiovascular conditions and has attracted public attention due to its high morbidity and mortality. Chronic kidney disease (CKD) is a common disease related to VC. Ginsenoside Rb1 (Rb1) has been reported to protect the cardiovascular system against vascular diseases, yet its role in VC and the underlying mechanisms remain unclear. In this study, we established a CKD‐associated VC rat model and a β‐glycerophosphate (β‐GP)‐induced vascular smooth muscle cell (VSMC) calcification model to investigate the effects of Rb1 on VC. Our results demonstrated that Rb1 ameliorated calcium deposition and VSMC osteogenic transdifferentiation both in vivo and in vitro. Rb1 treatment inhibited the Wnt/β‐catenin pathway by activating peroxisome proliferator‐activated receptor‐γ (PPAR‐γ), and confocal microscopy was used to show that Rb1 inhibited β‐catenin nuclear translocation in VSMCs. Furthermore, SKL2001, an agonist of the Wnt/β‐catenin pathway, compromised the vascular protective effect of Rb1. GW9662, a PPAR‐γ antagonist, reversed Rb1's inhibitory effect on β‐catenin. These results indicate that Rb1 exerted anticalcific properties through PPAR‐γ/Wnt/β‐catenin axis, which provides new insights into the potential theraputics of VC.

Leprosy drug clofazimine activates peroxisome proliferator-activated receptor-γ and synergizes with imatinib to inhibit chronic myeloid leukemia cells.

Leukemia stem cells contribute to drug-resistance and relapse in chronic myeloid leukemia (CML) and BCR-ABL1 inhibitor monotherapy fails to eliminate these cells, thereby necessitating alternate therapeutic strategies for patients CML. The peroxisome proliferator-activated receptor-γ (PPARγ) agonist pioglitazone downregulates signal transducer and activator of transcription 5 (STAT5) and in combination with imatinib induces complete molecular response in imatinib-refractory patients by eroding leukemia stem cells. Thiazolidinediones such as pioglitazone are, however, associated with severe side effects. To identify alternate therapeutic strategies for CML we screened Food and Drug Administration-approved drugs in K562 cells and identified the leprosy drug clofazimine as an inhibitor of viability of these cells. Here we show that clofazimine induced apoptosis of blood mononuclear cells derived from patients with CML, with a particularly robust effect in imatinib-resistant cells. Clofazimine also induced apoptosis of CD34+38− progenitors and quiescent CD34+ cells from CML patients but not of hematopoietic progenitor cells from healthy donors. Mechanistic evaluation revealed that clofazimine, via physical interaction with PPARγ, induced nuclear factor kB-p65 proteasomal degradation, which led to sequential myeloblastoma oncoprotein and peroxiredoxin 1 downregulation and concomitant induction of reactive oxygen species-mediated apoptosis. Clofazimine also suppressed STAT5 expression and consequently downregulated stem cell maintenance factors hypoxia-inducible factor-1α and -2α and Cbp/P300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2). Combining imatinib with clofazimine caused a far superior synergy than that with pioglitazone, with clofazimine reducing the half maximal inhibitory concentration (IC50) of imatinib by >4 logs and remarkably eroding quiescent CD34+ cells. In a K562 xenograft study clofazimine and imatinib co-treatment showed more robust efficacy than the individual treatments. We propose clinical evaluation of clofazimine in imatinib-refractory CML.

Estrogen and voluntary exercise attenuate cardiometabolic syndrome and hepatic steatosis in ovariectomized rats fed a high-fat high-fructose diet.

The prevalence of cardiometabolic syndrome (CMS) is increased in women after menopause. While hormone replacement therapy has been prescribed to relieve several components of CMS in postmenopausal women, some aspects of cardiometabolic dysfunction cannot be completely restored. The present study examined the effectiveness of estrogen replacement alone and in combination with exercise by voluntary wheel running (VWR) for alleviating the risks of CMS, insulin-mediated skeletal muscle glucose transport, and hepatic fat accumulation in ovariectomized Sprague-Dawley rats fed a high-fat high-fructose diet (OHFFD). We compared a sham-operated group with OHFFD rats that were subdivided into a sedentary, estradiol replacement (E2), and E2 plus VWR for 12 wk. E2 prevented the development of insulin resistance in skeletal muscle glucose transport and decreased hepatic fat accumulation in OHFFD rats. Furthermore, E2 treatment decreased visceral fat mass and low-density lipoprotein (LDL)-cholesterol in OHFFD rats, while VWR further decreased LDL-cholesterol and increased the ratio of high-density lipoprotein-cholesterol to total cholesterol to a greater extent. Although E2 treatment alone did not reduce serum triglyceride levels in OHFFD rats, the combined intervention of E2 and VWR lowered serum triglycerides in E2-treated OHFFD rats. The addition of VWR to E2-treated OHFFD rats led to AMPK activation and upregulation of peroxisome proliferator-activated receptor-γ (PPARγ) coactivator-1α and PPARδ in skeletal muscle along with increased fatty acid oxidation and suppressed fatty acid synthesis in the liver. Collectively, our findings indicate that, to achieve greater health benefits, physical exercise is required for E2-treated individuals under ovarian hormone deprivation with high-energy consumption.

Interleukin 4 inhibits high mobility group box-1 protein-mediated NLRP3 inflammasome formation by activating peroxisome proliferator-activated receptor-γ in astrocytes

High mobility group box-1 protein (HMGB-1) is one of the most important DAMPs and has been previously shown to promote the formation of the NOD-like receptor with pyrin domain containing-3 (NLRP3) inflammasome in microglia. Interleukin 4 (IL4) is a Th2-derived cytokine that plays a significant role in the function of various immune cells. However, the underlying molecular mechanism by which IL4 signaling antagonizes NLRP3 inflammasome is poorly characterized. In particular, whether IL4 could modulate NLRP3 inflammasome in astrocytes remains unknown. In the present study, we elucidated this phenomenon and the mechanism by which IL4 inhibits HMGB1-mediated NLRP3 inflammasome formation in astrocytes. For this purpose, we cultured and extracted primary astrocytes, setup different concentrations of HMGB1, and used immunofluorescence and western blotting to detect NLRP3 inflammasome formation, including NLRP3, ASC and caspase-1, and signaling changes in the nuclear factor κB (NF-κB). Meanwhile, BAY 11–7082 and IL4 were added with HMGB1 to observe the NLRP3 inflammasome and changes in NF-κB expression. Our data showed that HMGB1 could effectively promote NLRP3 inflammasome formation by activating NF-κB in astrocytes. This effect can be inhibited by BAY 11–7082, a NF-κB inhibitor. Meanwhile, IL4 could activate PPARγ via the STAT6 singling pathway and inhibit NF-κB activation, significantly decreasing formation of the NLRP3 inflammasome complex. Our study demonstrated that the NLRP3 inflammasome complex is also expressed in astrocytes, and IL4 could inhibit HMGB1-mediated NLRP3 inflammasome formation, through negative regulation of NF-κB activity and promotion of PPARγ activation.

Peroxisome proliferator-activated receptor-γ activation attenuates harmaline-induced cognitive impairments in rats

Cognitive and motor disturbances are serious concerns of the tremors induced by motor disorders. Despite the lack of effective clinical treatment, some potential therapeutic agents have been used to alleviate the cognitive symptoms in the animal models of tremor. Recent studies have shown that PPAR-γ agonists have neuroprotective effects. In the current study, the effects of pioglitazone (PIO), a peroxisome proliferator-activated receptor gamma agonist, on harmaline-induced motor and cognitive impairment were studied. Male Wistar rats were divided into vehicle (normal saline), PIO (20 mg/kg i.p.), harmaline (10 mg/kg, i.p.) and PIO + harmaline (PIO injected 2 h before harmaline) groups. Open field, rotarod, wire grip, foot print and Morris water maze tests were used to evaluate the motor and cognitive performance. The results indicated that administration of PIO attenuated harmaline-induced locomotor, anxiety-like behaviors, and spatial learning and memory impairments, but it partially decreased the tremor score. The neuroprotective and anxiolytic effects of PIO demonstrated in the current study can offer the PPAR-γ receptor agonism as a potential therapeutic agent in the treatment of patients with tremor that manifest mental dysfunction.

The effect of PPARγ inhibition on bone marrow adipose tissue and bone in C3H/HeJ mice.

Bone marrow adipose tissue (BMAT) increases after menopause, and increased BMAT is associated with osteoporosis and prevalent vertebral fractures. Peroxisome proliferator-activated receptor-γ (PPARγ) activation promotes adipogenesis and inhibits osteoblastogenesis; therefore, PPARγ is a potential contributor to the postmenopausal increase in BMAT and decrease in bone mass. The aim of this study is to determine if PPARγ inhibition can prevent ovariectomy-induced BMAT increase and bone loss in C3H/HeJ mice. Fourteen-week-old female C3H/HeJ mice ( n = 40) were allocated to four intervention groups: sham surgery (Sham) or ovariectomy (OVX; isoflurane anesthesia) with either vehicle (Veh) or PPARγ antagonist administration (GW9662; 1 mg·kg-1·day-1, daily intraperitoneal injections) for 3 wk. We measured BMAT volume, adipocyte size, adipocyte number. and bone structural parameters in the proximal metaphysis of the tibia using polyoxometalate-based contrast enhanced-nanocomputed topogaphy. Bone turnover was measured in the contralateral tibia using histomorphometry. The effects of surgery and treatment were analyzed by two-way ANOVA. OVX increased the BMAT volume fraction (Sham + Veh: 2.9 ± 2.7% vs. OVX + Veh: 8.1 ± 5.0%: P < 0.001), average adipocyte diameter (Sham + Veh: 19.3 ± 2.6 μm vs. OVX + Veh: 23.1 ± 3.4 μm: P = 0.001), and adipocyte number (Sham + Veh: 584 ± 337cells/μm3 vs. OVX + Veh: 824 ± 113cells/μm3: P = 0.03), while OVX decreased bone volume fraction (Sham + Veh: 15.5 ± 2.8% vs. OVX + Veh: 7.7 ± 1.9%; P < 0.001). GW9662 had no effect on BMAT, bone structural parameters, or bone turnover. In conclusion, ovariectomy increased BMAT and decreased bone volume in C3H/HeJ mice. The PPARγ antagonist GW9662 had no effect on BMAT or bone volume in C3H/HeJ mice, suggesting that BMAT accumulation is regulated independently of PPARγ in C3H/HeJ mice.

PPARα and γ Activation Effects of New Nor-triterpenoidal Saponins from the Aerial Parts of Anabasis articulata.

Anabasis articulata, traditionally used to treat diabetes, is rich in saponin content. This study was performed to investigate the agonistic effect of its saponins on peroxisome proliferator-activated receptor-α and peroxisome proliferator-activated receptor-γ in human hepatoma (HepG2) cells to explore the possibility of the involvement of these nuclear receptors in the mechanism of the antidiabetic effect of the plant. Chemical investigation of the n-butanol fraction resulted in the isolation of three new and one known 30-noroleanane triterpenoid saponins. The structures of the new compounds were elucidated as 3β-hydroxy,23-aldehyde-30-norolean-12,20(29)-dien-28-oic acid-28-O-β-D-glucopyranosyl ester (1: ), 3β-O-D-galactopyranosyl-23-aldehyde-30-norolean-12,20(29)-dien-28-oic acid-28-O-β-D-glucopyranosyl ester (2: ), and 3β-O-D-xylopyranosyl-30-norolean-12,20(29)-dien-28-oic acid 28-O-β-D-glucopyranosyl ester (3: ), while the known 30-nortriterpenoidal saponin was identified as boussingoside E (4: ). Although, the isolated saponins (1: - 4: ) did not show > 1.5-fold activation of peroxisome proliferator-activated receptor-γ, but two of them (1: and 3: ) activated peroxisome proliferator-activated receptor-α to the higher extents of 2.25- and 1.86-fold, respectively. These results suggest that the reported antidiabetic action of the isolated saponins may not solely involve the activation of peroxisome proliferator-activated receptor-γ. However, the agonistic activity of the n-butanol fraction of A. articulata (1.71-fold induction) and two of its saponins (1: and 3: ) towards peroxisome proliferator-activated receptor-α may be beneficial in the cardiovascular condition that is closely associated with diabetes and other metabolic disorders.

Honokiol Ameliorates Amyloidosis and Neuroinflammation and Improves Cognitive Impairment in Alzheimer's Disease Transgenic Mice.

The present study examined the effects of honokiol on amyloid-β (Aβ)-induced cognitive impairment and the underlying mechanisms in APPswe/PS1dE9 transgenic mice. The results showed that honokiol administration (20 mg/kg per day, intraperitoneally) for 6 weeks effectively improved spatial memory deficits in APPswe/PS1dE9 transgenic mice. Honokiol significantly lowered Aβ production and senile plaque deposition by downregulating β-site amyloid precursor protein cleavage enzyme 1 and enhancing Aβ phagocytosis by microglia. Honokiol reduced glial cell activation and the production of proinflammatory cytokines (TNF-α, IL-1β, and IL-6). Honokiol increased the transcriptional activity and protein levels of peroxisome proliferator-activated receptor-γ (PPARγ) However, all of the beneficial effects of honokiol on pathologic changes, including biochemistry and cognitive function, could be blocked by GW9662, a specific PPARγ inhibitor. These findings suggested that honokiol may be a natural PPARγ agonist, acting to attenuate Aβ generation and neuroinflammation. Therefore, honokiol may be a potential therapeutic approach for Alzheimer's disease.

Nrf2 activation protects against intratracheal LPS induced mouse/murine acute respiratory distress syndrome by regulating macrophage polarization

The transcription factor nuclear factor E2-related factor 2 (Nrf2) is known to control the expression of antioxidant response elements and cytoprotective genes and modulate inflammatory response, helping to ameliorate damage in many diseases. Exactly how Nrf2 regulates innate inflammatory homeostasis remains unclear. In this study, we provide in vitro and in vivo evidence that Nrf2 plays a crucial role in macrophage polarization and acute respiratory distress syndrome (ARDS). We conducted in vitro experiments using a mouse alveolar macrophage cell line as well as primary cultures of macrophages in which cells were exposed to lipopolysaccharide (LPS) or interferon-γ in order to mimic ARDS, in the presence or absence of the Nrf2 activator tert-butylhydroquinone (tBHQ). Using siRNA-mediated Nrf2 knockdown, we showed that Nrf2 inhibited the inflammatory response by promoting M2 macrophage polarization and inhibiting M1 macrophage polarization. At the same time, tBHQ activated Nrf2-mediated inhibition of the p65 nuclear factor-κB pathway and activation of peroxisome proliferator-activated receptor-γ, which play important roles in regulating macrophage polarization. We also conducted in vivo experiments in which mice were given tBHQ with or without intratracheal LPS, then their survival was monitored, lung injury was assessed using histology, and levels of pro- and anti-inflammatory cytokines were assayed in the lungs and serum. Activation of Nrf2 with tBHQ dramatically reduced LPS-induced mortality and lung injury, down-regulated pro-inflammatory mediators and up-regulated anti-inflammatory mediators. These results suggest that Nrf2 can help prevent ARDS progression by promoting M2 polarization of macrophages. Interfering with Nrf2 may be an effective strategy for reprogramming macrophage polarization in order to treat ARDS.

Histone demethylase JMJD1A coordinates acute and chronic adaptation to cold stress via thermogenic phospho-switch

In acute cold stress in mammals, JMJD1A, a histone H3 lysine 9 (H3K9) demethylase, upregulates thermogenic gene expressions through β-adrenergic signaling in brown adipose tissue (BAT). Aside BAT-driven thermogenesis, mammals have another mechanism to cope with long-term cold stress by inducing the browning of the subcutaneous white adipose tissue (scWAT). Here, we show that this occurs through a two-step process that requires both β-adrenergic-dependent phosphorylation of S265 and demethylation of H3K9me2 by JMJD1A. The histone demethylation-independent acute Ucp1 induction in BAT and demethylation-dependent chronic Ucp1 expression in beige scWAT provides complementary molecular mechanisms to ensure an ordered transition between acute and chronic adaptation to cold stress. JMJD1A mediates two major signaling pathways, namely, β-adrenergic receptor and peroxisome proliferator-activated receptor-γ (PPARγ) activation, via PRDM16-PPARγ-P-JMJD1A complex for beige adipogenesis. S265 phosphorylation of JMJD1A, and the following demethylation of H3K9me2 might prove to be a novel molecular target for the treatment of metabolic disorders, via promoting beige adipogenesis.