Novel ABCD1 Gene Mutation in a Korean Patient with X-Linked Adrenoleukodystrophy Presenting with Addison's Disease

X-linked adrenoleukodystrophy (X-ALD) occurs due to mutations in the ABCD1 gene that encodes the peroxisomal membrane protein peroxisomal transporter ATP-binding cassette sub-family D member 1 (ABCD1). Degradation of very long-chain fatty acids in peroxisomes is impaired owing to ABCD dysfunction, subsequently leading to adrenomyeloneuropathy, cerebral adrenoleukodystrophy, and adrenal insufficiency. X-ALD frequently induces idiopathic Addison's disease in young male patients. Here, we confirmed the diagnosis of X-ALD in a young male patient with primary adrenal insufficiency, and identified a novel ABCD1 gene mutation (p.Trp664*, c.1991 G>A).

15-Deoxy-Δ(12,14)-prostaglandin J₂ Upregulates the Expression of 15-Hydroxyprostaglandin Dehydrogenase by Inducing AP-1 Activation and Heme Oxygenase-1 Expression in Human Colon Cancer Cells

BACKGROUND: Abnormal upregulation of prostaglandin E₂ (PGE₂) is considered to be a key oncogenic event in the development and progression of inflammation-associated human colon cancer. It has been reported that 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme catabolizing PGE₂, is ubiquitously downregulated in human colon cancer. 15-Deoxy-Δ(12,14)-prostaglandin J₂ (15d-PGJ₂), a peroxisome proliferator-activated receptor γ ligand, has been shown to have anticarcinogenic activities. In this study, we investigate the effect of 15d-PGJ₂ on expression of 15-PGDH in human colon cancer HCT116 cells. METHODS: HCT116 cells were treated with 15d-PGJ₂ analysis. The expression of 15-PGDH in the treated cells was measured by Western blot analysis and RT-PCR. In addition, the cells were subjected to a 15-PGDH activity assay. To determine which transcription factor(s) and signaling pathway(s) are involved in 15d-PGJ₂-induced 15-PGDH expression, we performed a cDNA microarray analysis of 15d-PGJ₂-treated cells. The DNA binding activity of AP-1 was measured by an electrophoretic mobility shift assay. To determine whether the AP-1 plays an important role in the 15d-PGJ₂-induced 15-PGDH expression, the cells were transfected with siRNA of c-Jun, a major subunit of AP-1. To elucidate the upstream signaling pathways involved in AP-1 activation by 15d-PGJ₂, we examined its effect on phosphorylation of Akt by Western blot analysis in the presence or absence of kinase inhibitor. RESULTS: 15d-PGJ₂ (10 μM) significantly upregulated 15-PGDH expression at the mRNA and protein levels in HCT-116 cells. 15-PGDH activity was also elevated by 15d-PGJ₂. We observed that genes encoding C/EBP delta, FOS-like antigen 1, c-Jun, and heme oxygenase-1 (HO-1) were most highly induced in the HCT116 cells following 15d-PGJ₂ treatment. 15d-PGJ₂ increased the DNA binding activity of AP-1. Moreover, transfection with specific siRNA against c-Jun significantly reduced 15-PGDH expression induced by 15d-PGJ₂. 15d-PGJ₂ activates Akt and a pharmacological inhibitor of Akt, LY294002, abrogated 15d-PGJ₂-induced 15-PGDH expression. We also observed that an inhibitor of HO-1, zinc protoporphyrin IX, also abrogated upregulation of 15-PGDH and down-regulation of cyclooxygenase-2 expression induced by 15d-PGJ₂. CONCLUSIONS: These finding suggest that 15d-PGJ₂ upregulates the expression of 15-PGDH through AP-1 activation in colon cancer HCT116 cells.

Deficiency or activation of peroxisome proliferator-activated receptor α reduces the tissue concentrations of endogenously synthesized docosahexaenoic acid in C57BL/6J mice

BACKGROUND/OBJECTIVES: Docosahexaenoic acid (DHA), an n-3 long chain polyunsaturated fatty acid (LCPUFA), is acquired by dietary intake or the in vivo conversion of α-linolenic acid. Many enzymes participating in LCPUFA synthesis are regulated by peroxisome proliferator-activated receptor alpha (PPARα). Therefore, it was hypothesized that the tissue accretion of endogenously synthesized DHA could be modified by PPARα. MATERIALS/METHODS: The tissue DHA concentrations and mRNA levels of genes participating in DHA biosynthesis were compared among PPARα homozygous (KO), heterozygous (HZ), and wild type (WT) mice (Exp I), and between WT mice treated with clofibrate (PPARα agonist) or those not treated (Exp II). In ExpII, the expression levels of the proteins associated with DHA function in the brain cortex and retina were also measured. An n3-PUFA depleted/replenished regimen was applied to mitigate the confounding effects of maternal DHA. RESULTS: PPARα ablation reduced the hepatic Acox, Fads1, and Fads2 mRNA levels, as well as the DHA concentration in the liver, but not in the brain cortex. In contrast, PPARα activation increased hepatic Acox, Fads1, Fads2 and Elovl5 mRNA levels, but reduced the DHA concentrations in the liver, retina, and phospholipid of brain cortex, and decreased mRNA and protein levels of the brain-derived neurotrophic factor in brain cortex. CONCLUSIONS: LCPUFA enzyme expression was altered by PPARα. Either PPARα deficiency or activation-decreased tissue DHA concentration is a stimulus for further studies to determine the functional significance.

Nicotinamide riboside regulates inflammation and mitochondrial markers in AML12 hepatocytes

BACKGROUND/OBJECTIVES: The NAD+ precursor nicotinamide riboside (NR) is a type of vitamin B3 found in cow's milk and yeast-containing food products such as beer. Recent studies suggested that NR prevents hearing loss, high-fat diet-induced obesity, Alzheimer's disease, and mitochondrial myopathy. The objective of this study was to investigate the effects of NR on inflammation and mitochondrial biogenesis in AML12 mouse hepatocytes. MATERIALS/METHODS: A subset of hepatocytes was treated with palmitic acid (PA; 250 µM) for 48 h to induce hepatocyte steatosis. The hepatocytes were treated with NR (10 µM and 10 mM) for 24 h with and without PA. The cell viability and the levels of sirtuins, inflammatory markers, and mitochondrial markers were analyzed. RESULTS: Cytotoxicity of NR was examined by PrestoBlue assay. Exposure to NR had no effect on cell viability or morphology. Gene expression of sirtuin 1 (Sirt1) and Sirt3 was significantly upregulated by NR in PA-treated hepatocytes. However, Sirt1 activities were increased in hepatocytes treated with low-dose NR. Hepatic pro-inflammatory markers including tumor necrosis factor-alpha and interleukin-6 were decreased in NR-treated cells. NR upregulated anti-inflammatory molecule adiponectin, and, tended to down-regulate hepatokine fetuin-A in PA-treated hepatocytes, suggesting its inverse regulation on these cytokines. NR increased levels of mitochondrial markers including peroxisome proliferator-activated receptor γ coactivator-1α, carnitine palmitoyltransferase 1, uncoupling protein 2, transcription factor A, mitochondrial and mitochondrial DNA in PA-treated hepatocytes. CONCLUSIONS: These data demonstrated that NR attenuated hepatic inflammation and increased levels of mitochondrial markers in hepatocytes.

Fumigaclavine C attenuates adipogenesis in 3T3-L1 adipocytes and ameliorates lipid accumulation in high-fat diet-induced obese mice

Fumigaclavine C (FC), an active indole alkaloid, is obtained from endophytic Aspergillus terreus (strain No. FC118) by the root of Rhizophora stylosa (Rhizophoraceae). This study is designed to evaluate whether FC has anti-adipogenic effects in 3T3-L1 adipocytes and whether it ameliorates lipid accumulation in high-fat diet (HFD)-induced obese mice. FC notably increased the levels of glycerol in the culture supernatants and markedly reduced lipid accumulation in 3T3-L1 adipocytes. FC differentially inhibited the expressions of adipogenesis-related genes, including the peroxisome proliferator-activated receptor proteins, CCAAT/enhancer-binding proteins, and sterol regulatory element-binding proteins. FC markedly reduced the expressions of lipid synthesis-related genes, such as the fatty acid binding protein, lipoprotein lipase, and fatty acid synthase. Furthermore, FC significantly increased the expressions of lipolysis-related genes, such as the hormone-sensitive lipase, Aquaporin-7, and adipose triglyceride lipase. In HFD-induced obese mice, intraperitoneal injections of FC decreased both the body weight and visceral adipose tissue weight. FC administration significantly reduced lipid accumulation. Moreover, FC could dose-dependently and differentially regulate the expressions of lipid metabolism-related transcription factors. All these data indicated that FC exhibited anti-obesity effects through modulating adipogenesis and lipolysis.

Telmisartan increases hepatic glucose production via protein kinase C ζ-dependent insulin receptor substrate-1 phosphorylation in HepG2 cells and mouse liver / 영남의대학술지

BACKGROUND: Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.METHODS: Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.RESULTS: Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser302) and decreased p-IRS-1-Tyr632 dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr410 which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser302 and -inhibited p-IRS-1-Tyr632. Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser302 and decreased p-IRS-1-Tyr632, which was accompanied by an increase in p-PKCζ-Thr410.CONCLUSION: These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr410 that increases p-IRS-1-Ser302 and decreases p-IRS-1-Tyr632 in a PPARγ-independent manner.

The Activation of PPAR-α and Wnt/β-catenin by Luffa cylindrica Supercritical Carbon Dioxide Extract

Luffa cylindrica (LC) is a very fast-growing climber and its fruit have been considered as agricultural wastes. We conducted to check the comparative qualities of ethanol solvent extraction (LCE) and supercritical carbon dioxide extraction (LCS) of L. cylindrica fruit and seed. LCS had higher antioxidant and polyphenol contents than LCE. LCS were significantly increased peroxisome proliferator-activated receptor (PPAR)-a and involucrin expression as epidermal differentiation marker in 3D skin equivalent model. LCS also showed antimicrobial activity against Staphylococcus aureus, a causative bacteria in atopic dermatitis. In addition, LCS inhibited the adipocyte differentiation of 3T3-L1 cells. When treated with the extract at a concentration of 100 µg/mL, the Wnt/β-catenin pathway reporter luciferase activity of HEK 293-TOP cells was increased approximately by 2-folds compared to that of the untreated control group. These results indicate that L. cylindrica supercritical carbon dioxide extract may serve as a cosmeceutical for improving skin barrier function and the treatment of obesity.

Cryptotanshinone Inhibits Lipid Accumulation in Differentiating 3T3-L1 Preadipocytes by Down-regulating C/EBP-α, PPAR-γ, FAS, Perilipin A, and STAT-3 / 계명의대학술지

Differentiation of preadipocyte, also named adipogenesis, leads to the phenotype of mature adipocyte that is filled with many lipid droplets. Excessive lipid accumulation in adipocytes leads to the development of obesity. In this study, we investigated the effect of 11 different natural compounds on lipid accumulation during the differentiation of 3T3-L1 preadipocytes into 3T3-L1 adipocytes. Strikingly, among the natural compounds, cryptotanshinone at 10 µM most strongly reduced triglyceride (TG) contents in 3T3-L1 cells after 8 days of the differentiation. Furthermore, cryptotanshinone at 10 µM significantly suppressed lipid accumulation in 3T3-L1 cells after 8 days of the differentiation. Cryptotanshinone at 1 to 10 µM tested did not affect the survival of 3T3-L1 cells after 8 days of the differentiation. On mechanistic levels, cryptotanshinone time-differentially decreased the expression levels of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A but also the phosphorylation levels of signal transducer and activator of transcription-3 (STAT-3) during the 3T3-L1 cell differentiation. Taken together, these findings demonstrate that cryptotanshinone inhibits lipid accumulation in differentiating 3T3-L1 cells, which appears to be mediated through the reduced expression and/or phosphorylation levels of C/EBP-α, PPAR-γ, FAS, Perilipin A, and STAT-3.

Effects of Lonicera caerulea extract on adipocyte differentiation and adipogenesis in 3T3-L1 cells and mouse adipose-derived stem cells (MADSCs) / 한국영양학회지

PURPOSE: Obesity is a major health problem of global significance because it is clearly associated with an increased risk of health problems, such as nonalcoholic fatty liver disease (NAFLD), diabetes, cardiovascular diseases, and cancer. Lonicera caerulea (LC) originates from high mountains or wet areas and has been used as a traditional medicine in northern Russia, China, and Japan. LC contains a range of bioactive constituents, such as vitamins, minerals, and polyphenols. This study examined the anti-obesity effects of LC during differentiation in preadipocytes. METHODS: The cell viability assay was performed after the differentiation of 3T3-L1 cells for 7 days. Oil Red O staining was used to visualize the changes in lipid droplets in 3T3-L1 cells and mouse adipose-derived stem cells (MADSCs). The mRNA expression of obesity-related genes was determined by quantitative real-time PCR. RESULTS: According to the results of Oil Red O staining, the lipid levels and size of lipid droplets in the adipocytes were reduced and the LC extract (LCE, 0.25–1 mg/mL) markedly inhibited adipogenesis in a dose-dependent manner. The treatment of LCE also decreased the mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein-α (C/EBPα), and sterol regulatory element binding protein 1 (SREBP1) in 3T3-L1 cells. Western blot analysis showed that the PPARγ, C/EBPα, and SREBP1 protein levels in both 3T3-L1 and MADSC were reduced in a dose-dependent manner. CONCLUSION: These results suggest that LCE can inhibit adipogenic differentiation through the regulation of adipogenesis-related markers.

Telmisartan Inhibits Nitric Oxide Production and Vessel Relaxation via Protein Phosphatase 2A-mediated Endothelial NO Synthase-Ser¹¹⁷⁹ Dephosphorylation

BACKGROUND: Apart from its blood pressure-lowering effect by blocking the renin-angiotensin-aldosterone system, telmisartan, an angiotensin II type 1 receptor blocker (ARB), exhibits various ancillary effects including cardiovascular protective effects in vitro. Nonetheless, the protective effects of telmisartan in cerebrocardiovascular diseases are somewhat variable in large-scale clinical trials. Dysregulation of endothelial nitric oxide (NO) synthase (eNOS)-derived NO contributes to the developments of various vascular diseases. Nevertheless, the direct effects of telmisartan on endothelial functions including NO production and vessel relaxation, and its action mechanism have not been fully elucidated. Here, we investigated the mechanism by which telmisartan regulates NO production and vessel relaxation in vitro and in vivo. METHODS: We measured nitrite levels in culture medium and mouse serum, and performed inhibitor studies and western blot analyses using bovine aortic endothelial cells (BAECs) and a hyperglycemic mouse model. To assess vessel reactivity, we performed acetylcholine (ACh)-induced vessel relaxation assay on isolated rat aortas. RESULTS: Telmisartan decreased NO production in normoglycemic and hyperglycemic BAECs, which was accompanied by reduced phosphorylation of eNOS at Ser¹¹⁷⁹ (p-eNOS-Ser¹¹⁷⁹). Telmisartan increased the expression of protein phosphatase 2A catalytic subunit (PP2Ac) and co-treatment with okadaic acid completely restored telmisartan-inhibited NO production and p-eNOS-Ser¹¹⁷⁹ levels. Of the ARBs tested (including losartan and fimasartan), only telmisartan decreased NO production and p-eNOS-Ser¹¹⁷⁹ levels, and enhanced PP2Ac expression. Co-treatment with GW9662 had no effect on telmisartan-induced changes. In line with in vitro observations, telmisartan reduced serum nitrite and p-eNOS-Ser¹¹⁷⁹ levels, and increased PP2Ac expression in high fat diet-fed mice. Furthermore, telmisartan attenuated ACh-induced rat aorta relaxation. CONCLUSION: We demonstrated that telmisartan inhibited NO production and vessel relaxation at least in part by PP2A-mediated eNOS-Ser¹¹⁷⁹ dephosphorylation in a peroxisome proliferator-activated receptor γ-independent manner. These results may provide a mechanism that explains the inconsistent cerebrocardiovascular protective effects of telmisartan.

Leucrose, a Sucrose Isomer, Suppresses Hepatic Fat Accumulation by Regulating Hepatic Lipogenesis and Fat Oxidation in High-fat Diet-induced Obese Mice

Obesity is currently one of the most serious public health problems and it can lead to numerous metabolic diseases. Leucrose, d-glucopyranosyl-α-(1-5)-d-fructopyranose, is an isoform of sucrose and it is naturally found in pollen and honey. The aim of this study was to investigate the effect of leucrose on metabolic changes induced by a high-fat diet (HFD) that lead to obesity. C57BL/6 mice were fed a 60% HFD or a HFD with 25% (L25) or 50% (L50) of its total sucrose content replaced with leucrose for 12 weeks. Leucrose supplementation improved fasting blood glucose levels and hepatic triglyceride content. In addition, leucrose supplementation reduced mRNA levels of lipogenesis-related genes, including peroxisome proliferator-activated receptor γ, sterol regulatory element binding protein 1C, and fatty acid synthase in HFD mice. Conversely, mRNA levels of β oxidation-related genes, such as carnitine palmitoyltransferase 1A and acyl CoA oxidase, returned to control levels with leucrose supplementation. Taken together, these results demonstrated the therapeutic potential of leucrose to prevent metabolic abnormalities by mediating regulation of plasma glucose level and hepatic triglyceride accumulation.

Suppressive Effect of 4-Hydroxy-2-(4-Hydroxyphenethyl) Isoindoline-1,3-Dione on Ovalbumin-Induced Allergic Asthma

4-Hydroxy-2-(4-hydroxyphenethyl)isoindoline-1,3-dione (PD1) is a synthetic phthalimide derivative of a marine compound. PD1 has peroxisome proliferator-activated receptor (PPAR) γ agonistic and anti-inflammatory effects. This study aimed to investigate the effect of PD1 on allergic asthma using rat basophilic leukemia (RBL)-2H3 mast cells and an ovalbumin (OVA)-induced asthma mouse model. In vitro, PD1 suppressed β-hexosaminidase activity in RBL-2H3 cells. In the OVA-induced allergic asthma mouse model, increased inflammatory cells and elevated Th2 and Th1 cytokine levels were observed in bronchoalveolar lavage fluid (BALF) and lung tissue. PD1 administration decreased the numbers of inflammatory cells, especially eosinophils, and reduced the mRNA and protein levels of the Th2 cytokines including interleukin (IL)-4 and IL-13, in BALF and lung tissue. The severity of inflammation and mucin secretion in the lungs of PD1-treated mice was also less. These findings indicate that PD1 could be a potential compound for anti-allergic therapy.

The effects of Brassica juncea L. leaf extract on obesity and lipid profiles of rats fed a high-fat/high-cholesterol diet

BACKGROUND/OBJECTIVES: Obesity is a global health problem of significant importance which increases mortality. In place of anti-obesity drugs, natural products are being developed as alternative therapeutic materials. In this study, we investigated the effect of Brassica juncea L. leaf extract (BLE) on fat deposition and lipid profiles in high-fat, high-cholesterol diet (HFC)-induced obese rats. MATERIALS/METHODS: Male Sprague-Dawley rats were divided into four groups (n = 8 per group) according to diet: normal diet group (ND), high-fat/high-cholesterol diet group (HFC), HFC with 3% BLE diet group (HFC-A1), and HFC with 5% BLE diet group (HFC-A2). Each group was fed for 6 weeks. Rat body and adipose tissue weights, serum biochemical parameters, and tissue lipid contents were determined. The expression levels of mRNA and proteins involved in lipid and cholesterol metabolism were determined by reverse transcription polymerase chain reaction and western blot analysis, respectively. RESULTS: The HFC-A2 group showed significantly lower body weight gain and food efficiency ratio than the HFC group. BLE supplementation caused mesenteric, epididymal, and total adipose tissue weights to decrease. The serum levels of triglyceride, total cholesterol, and low-density lipoprotein cholesterol were significantly reduced, and high-density lipoprotein cholesterol was significantly increased in rats fed BLE. These results were related to lower glucose-6-phosphate dehydrogenase, acetyl-coA carboxylase, and fatty acid synthase mRNA expression, and to higher expression of the cholesterol 7α-hydroxylase and low density lipoprotein-receptor, as well as increased protein levels of peroxisome proliferator-activated receptor α. Histological analysis of the liver revealed decreased lipid droplets in HFC rats treated with BLE. CONCLUSIONS: Supplementation of HFC with 3% or 5% BLE inhibited body fat accumulation, improved lipid profiles, and modulated lipogenesis- and cholesterol metabolism-related gene and protein expression.

Troglitazone Inhibits Matrix Metalloproteinase-9 Expression and Invasion of Breast Cancer Cell through a Peroxisome Proliferator-Activated Receptor γ-Dependent Mechanism / 한국유방암학회지

PURPOSE: Peroxisome proliferator-activated receptor γ (PPARγ) is involved in the pathology of numerous diseases including atherosclerosis, diabetes, obesity, and cancer. Matrix metalloproteinases (MMPs) play a significant role in tissue remodeling related to various processes such as morphogenesis, angiogenesis, tissue repair, invasion, and metastasis. We investigated the effects of PPARγ on MMP expression and invasion in breast cancer cells. METHODS: MCF-7 cells were cultured and then cell viability was monitored in an MTT assay. Western blotting, gelatin zymography, real-time polymerase chain reaction, and luciferase assays were performed to investigate the effect of the synthetic PPARγ ligand troglitazone on MMP expression. Transcription factor DNA binding was analyzed by electrophoretic mobility shift assay. A Matrigel invasion assay was used to assess the effects of troglitazone on MCF-7 cells. RESULTS: Troglitazone did not affect MCF-7 cell viability. 12-O-tetradecanoylphorbol-13-acetate (TPA) induced MMP-9 expression and invasion in MCF-7 cell. However, these effects were decreased by troglitazone. TPA increased nuclear factor κB and activator protein-1 DNA binding, while troglitazone inhibited these effects. The selective PPARγ antagonist GW9662 reversed MMP-9 inhibition by troglitazone in TPA-treated MCF-7 cells. CONCLUSION: Troglitazone inhibited nuclear factor κB and activator protein-1-mediated MMP-9 expression and invasion of MCF-7 cells through a PPARγ-dependent mechanism.

Compound K attenuates glucose intolerance and hepatic steatosis through AMPK-dependent pathways in type 2 diabetic OLETF rats

BACKGROUND/AIMS: Non-alcoholic fatty liver disease is associated with insulin resistance. Compound K (CK) is the final metabolite of panaxadiol ginsenosides that have been shown to exert antidiabetic effects. However, the molecular mechanism of the antidiabetic effects in the liver have not been elucidated; further, whether CK has beneficial effects in hepatosteatosis remains unclear. Therefore, we evaluated the effect of CK on hepatosteatosis as well as its mechanism in high-fat diet (HFD)-fed type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. METHODS: Twenty-four-week-old male OLETF rats were assigned to four groups: control (saline), CK 10 mg/kg, CK 25 mg/kg, or metformin 300 mg/kg (positive control); all treatments were administered orally for 12 weeks. RESULTS: Fasting glucose levels of the CK25 group were significantly lower than those of the control group during the 12 weeks. The results of the oral glucose tolerance test showed that both the glucose concentration after glucose loading and the fasting insulin levels of the CK25 group were significantly lower than those of the control. Hepatosteatosis was significantly improved by CK25. CK25 and metformin significantly increased the phosphorylation of hepatic adenosine monophosphate-activated protein kinase (AMPK). CK25 significantly inhibited the expression of sterol regulatory element-binding protein-1c and fatty acid synthase, while upregulating that of peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase-1. CONCLUSIONS: CK improved glucose intolerance and hepatosteatosis in HFD-fed OLETF rats through AMPK activation, which has dual mode of action that involves decreasing the synthesis of fatty acids and increasing fatty acid oxidation.

Pioglitazone Attenuates Palmitate-Induced Inflammation and Endoplasmic Reticulum Stress in Pancreatic β-Cells

BACKGROUND: The nuclear receptor peroxisome proliferator-activator gamma (PPARγ) is a useful therapeutic target for obesity and diabetes, but its role in protecting β-cell function and viability is unclear. METHODS: To identify the potential functions of PPARγ in β-cells, we treated mouse insulinoma 6 (MIN6) cells with the PPARγ agonist pioglitazone in conditions of lipotoxicity, endoplasmic reticulum (ER) stress, and inflammation. RESULTS: Palmitate-treated cells incubated with pioglitazone exhibited significant improvements in glucose-stimulated insulin secretion and the repression of apoptosis, as shown by decreased caspase-3 cleavage and poly (adenosine diphosphate [ADP]-ribose) polymerase activity. Pioglitazone also reversed the palmitate-induced expression of inflammatory cytokines (tumor necrosis factor α, interleukin 6 [IL-6], and IL-1β) and ER stress markers (phosphor-eukaryotic translation initiation factor 2α, glucose-regulated protein 78 [GRP78], cleaved-activating transcription factor 6 [ATF6], and C/EBP homologous protein [CHOP]), and pioglitazone significantly attenuated inflammation and ER stress in lipopolysaccharide- or tunicamycin-treated MIN6 cells. The protective effect of pioglitazone was also tested in pancreatic islets from high-fat-fed KK-Ay mice administered 0.02% (wt/wt) pioglitazone or vehicle for 6 weeks. Pioglitazone remarkably reduced the expression of ATF6α, GRP78, and monocyte chemoattractant protein-1, prevented α-cell infiltration into the pancreatic islets, and upregulated glucose transporter 2 (Glut2) expression in β-cells. Moreover, the preservation of β-cells by pioglitazone was accompanied by a significant reduction of blood glucose levels. CONCLUSION: Altogether, these results support the proposal that PPARγ agonists not only suppress insulin resistance, but also prevent β-cell impairment via protection against ER stress and inflammation. The activation of PPARγ might be a new therapeutic approach for improving β-cell survival and insulin secretion in patients with diabetes mellitus

Galangin Suppresses Pro-Inflammatory Gene Expression in Polyinosinic-Polycytidylic Acid-Stimulated Microglial Cells

Galangin (3,5,7-trihydroxyflavone) is a polyphenolic compound abundant in honey and medicinal herbs, such as Alpinia officinarum. In this study, we investigated the anti-inflammatory effects of galangin under in vitro and in vivo neuroinflammatory conditions caused by polyinosinic-polycytidylic acid (poly(I:C)), a viral mimic dsRNA analog. Galangin suppressed the production of nitric oxide, reactive oxygen species, and pro-inflammatory cytokines in poly(I:C)-stimulated BV2 microglia. On the other hand, galangin enhanced anti-inflammatory interleukin (IL)-10 production. Galangin also suppressed the expression of pro-inflammatory markers in poly(I:C)-injected mouse brains. Further mechanistic studies showed that galangin inhibited poly(I:C)-induced nuclear factor (NF)-κB activity and phosphorylation of Akt without affecting MAP kinases. Interestingly, galangin increased the expression and transcriptional activity of peroxisome proliferator-activated receptor (PPAR)-γ, known to play an anti-inflammatory role. To investigate whether PPAR-γ is involved in the anti-inflammatory function of galangin, BV2 cells were pre-treated with PPAR-γ antagonist before treatment of galangin. We found that PPAR-γ antagonist significantly blocked galangin-mediated upregulation of IL-10 and attenuated the inhibition of tumor necrosis factor (TNF)-α and IL-6 in poly(I:C)-stimulated microglia. In conclusion, our data suggest that PI3K/Akt, NF-κB, and PPAR-γ play a pivotal role in mediating the anti-inflammatory effects of galangin in poly(I:C)-stimulated microglia.

Galangin Suppresses Pro-Inflammatory Gene Expression in Polyinosinic-Polycytidylic Acid-Stimulated Microglial Cells

Galangin (3,5,7-trihydroxyflavone) is a polyphenolic compound abundant in honey and medicinal herbs, such as Alpinia officinarum. In this study, we investigated the anti-inflammatory effects of galangin under in vitro and in vivo neuroinflammatory conditions caused by polyinosinic-polycytidylic acid (poly(I:C)), a viral mimic dsRNA analog. Galangin suppressed the production of nitric oxide, reactive oxygen species, and pro-inflammatory cytokines in poly(I:C)-stimulated BV2 microglia. On the other hand, galangin enhanced anti-inflammatory interleukin (IL)-10 production. Galangin also suppressed the expression of pro-inflammatory markers in poly(I:C)-injected mouse brains. Further mechanistic studies showed that galangin inhibited poly(I:C)-induced nuclear factor (NF)-κB activity and phosphorylation of Akt without affecting MAP kinases. Interestingly, galangin increased the expression and transcriptional activity of peroxisome proliferator-activated receptor (PPAR)-γ, known to play an anti-inflammatory role. To investigate whether PPAR-γ is involved in the anti-inflammatory function of galangin, BV2 cells were pre-treated with PPAR-γ antagonist before treatment of galangin. We found that PPAR-γ antagonist significantly blocked galangin-mediated upregulation of IL-10 and attenuated the inhibition of tumor necrosis factor (TNF)-α and IL-6 in poly(I:C)-stimulated microglia. In conclusion, our data suggest that PI3K/Akt, NF-κB, and PPAR-γ play a pivotal role in mediating the anti-inflammatory effects of galangin in poly(I:C)-stimulated microglia.

Sex-specific regulation of immune responses by PPARs

The prevalence of autoimmune, infectious and metabolic diseases is different for men and women owing to the respective ability of their immune systems to respond to self and foreign antigens. Although several factors, including hormones and the X-chromosome, have been suggested to contribute to such sex-specific immune responses, the underlying factors remain poorly defined. Recent studies using peroxisome proliferator-activated receptor (PPAR) ligands and knockout mice have identified sex-dimorphic expression of PPARs, and have shown that the inhibitory functions of PPAR in T cells are substantially affected by the sex hormones. In this review, we consider the sex-specific differences in PPARs and summarize the diverse PPAR-mediated, sex-specific properties of effector T-cell responses, such as T-cell activation, survival and differentiation, as well as their involvement in T-cell-related autoimmune diseases, including colitis, graft-versus-host disease and experimental autoimmune encephalomyelitis. Understanding PPAR-mediated sex differences in immune responses will provide more precise insights into the roles of PPARs in effector T cells.

Treatment Options in Non-alcoholic Fatty Liver Disease / 대한소화기학회지

The prevalence of non-alcoholic fatty liver disease (NAFLD) has sharply increased over the past several decades in Korea. In most cases of NAFLD, metabolic stress and cellular apoptosis are often driven by metabolic abnormality, eventually leading to inflammation and fibrosis . Along with a dramatic surge in the obesity epidemic, 10–20% of NAFLD patients ultimately progress to non-alcoholic steatohepatitis (NASH), a precursor to cirrhosis and hepatocellular carcinoma, as well as multi-organ systemic diseases. Currently, diet and exercise are chiefly recommended to achieve significant weight loss and improve metabolic dysfunction in patients with NAFLD. However, weight loss remains to be an elusive goal for both clinical practitioners and NAFLD patients. To date, although there has not been any proven pharmacotherapy against NAFLD, numerous promising pipelines with good target engagement are under development. Moreover, given the global landmark phase 3 trials using obeticholic acid (a farnesoid X receptor agonist, REGENERATE trial) and elafibranor (a dual peroxisome proliferator-activated receptor α/δ agonist, RESOLVE-IT trial), the era of specific target therapies focusing on molecular and metabolic pathogenesis of NASH and fibrosis is near at hand. In this paper, we briefly cover the current and future therapeutic options in patients with NAFLD across the entire spectrum of diseases.