Levels Of Peroxisome Proliferator-activated Receptor Research Articles

Gestational organophosphate esters (OPEs) exposure in association with placental DNA methylation levels of peroxisome proliferator-activated receptors (PPARs) signaling pathway-related genes

BackgroundOrganophosphate esters (OPEs) exposure could affect offspring health. However, the underlying mechanisms are not well documented. ObjectivesBased on a birth cohort study, we aimed to investigate the associations among gestational OPEs exposure, placental DNA methylation levels of peroxisome proliferator-activated receptor (PPAR) signaling pathway-related genes, and fetal growth. MethodsWe measured the concentrations of eight OPE metabolites in maternal urine samples and neonatal anthropometric measurements in 733 mother-child pairs. In 327 placental samples, we assessed the DNA methylation levels of 14 genes which were involved in the PPARs signaling pathway and expressed in placenta. Multiple linear regression models were used to examine the associations of OPEs exposure with placental DNA methylation, and of OPEs and placental DNA methylation with neonatal anthropometric measurements. Causal mediation analyses were conducted to examine the potential mediating role of placental DNA methylation in the pathway between OPEs exposure and fetal growth. ResultsWe observed a general pattern of OPEs exposure being associated with hypermethylation of candidate genes, with statistically significant associations identified for several OPEs with RXRA, ACAA1, ACADL, ACADM, PLTP, and NR1H3 methylation. Further, gestational exposure to BCIPP, DPP, BBOEP, ∑NCl-OPEs, and ∑OPEs tended to be associated with lower anthropometric measurements, with more significant associations observed on arm circumference, and abdominal and back skinfold thickness. Notably, RXRA, ACAA1, ACOX1, CPT2, ACADM, and NR1H3 methylation tended to be associated with lower neonatal anthropometric measurements, especially for abdominal and back skinfold thickness. Moreover, mediation analyses showed that 19.42 % of the total effect of DPP on the back skinfold thickness was mediated by changes in RXRA methylation, and there was a significant indirect effect of RXRA methylation. ConclusionsGestational OPEs exposure could disrupt the placental DNA methylation levels of PPAR signaling pathway-related genes, which might contribute to the effect of OPEs on fetal growth.

Osthole ameliorates chronic pruritus in 2,4-dichloronitrobenzene-induced atopic dermatitis by inhibiting IL-31 production

ObjectiveThis study aims to elucidate the therapeutic potential of osthole for the treatment of atopic dermatitis (AD), focusing on its ability to alleviate chronic pruritus (CP) and the underlying molecular mechanisms. MethodsIn this study, we investigated the anti-inflammatory effects of osthole in both a 2,4-dichloronitrobenzene (DNCB)-induced AD mouse model and tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) stimulated human immortalized epidermal (HaCaT) cells. The anti-itch effect of osthole was specifically assessed in the AD mouse model. Using methods such as hematoxylin and eosin (HE) staining, enzyme-linked immunosorbent assay (ELISA), western blot (WB), quantitative real-time PCR (qRT-PCR), and immunofluorescence staining. ResultsOsthole improved skin damage and clinical dermatitis scores, reduced scratching bouts, and decreased epidermal thickness in AD-like mice. It also reduced the levels of interleukin (IL)-31 and IL-31 receptor A (IL-31 RA) in both skin tissues and HaCaT cells. Furthermore, Osthole suppressed the protein expression levels of phosphor-p65 (p-p65) and phosphor-inhibitor of nuclear factor kappa-Bα (p-IκBα). Meanwhile, it increased the protein expression levels of peroxisome proliferator-activated receptor α (PPARα) and PPARγ in HaCaT cells. ConclusionThese findings indicated that osthole effectively inhibited CP in AD by activating PPARα, PPARγ, repressing the NF-κB signaling pathway, as well as the expression of IL-31 and IL-31 RA.

Cinnamic acid, a natural plant compound, exhibits neuroprotection in a mouse model of Sandhoff disease via PPARα.

Tay-Sachs disease (TSD) and its severe form Sandhoff disease (SD) are autosomal recessive lysosomal storage metabolic disorders, which often result into excessive GM2 ganglioside accumulation predominantly in lysosomes of nerve cells. Although patients with these diseases appear normal at birth, the progressive accumulation of undegraded GM2 gangliosides in neurons leads to early death accompanied by manifestation of motor difficulties and gradual loss of behavioral skills. Unfortunately, there is still no effective treatment available for TSD/SD. The present study highlights the importance of cinnamic acid (CA), a naturally occurring aromatic fatty acid present in a number of plants, in inhibiting the disease process in a transgenic mouse model of SD. Oral administration of CA significantly attenuated glial activation and inflammation and reduced the accumulation of GM2 gangliosides/glycoconjugates in the cerebral cortex of Sandhoff mice. Besides, oral CA also improved behavioral performance and increased the survival of Sandhoff mice. While assessing the mechanism, we found that oral administration of CA increased the level of peroxisome proliferator-activated receptor α (PPARα) in the brain of Sandhoff mice and that oral CA remained unable to reduce glycoconjugates, improve behavior and increase survival in Sandhoff mice lacking PPARα. Our results indicate a beneficial function of CA that utilizes a PPARα-dependent mechanism to halt the progression of SD and thereby increase the longevity of Sandhoff mice.

Zhuyu Pills promote polarization of macrophages toward M2 phenotype to prevent atherosclerosis via PPARγ/NF-κB signaling pathway

This article aims to investigate the effect of Zhuyu Pills on atherosclerosis and decipher the underlying mechanism. The mouse model of atherosclerosis was induced by a high-fat diet, and the total modeling period was 12 weeks. A total of 47 ApoE~(-/-) mice successfully modeled were randomized into 5 groups, including 10 in the model group, 9 in each of low-, medium-, and high-dose(130.54, 261.08 and 522.16 mg·kg~(-1)·d~(-1), respectively) Zhuyu Pills groups, and 10 in the atorvastatin calcium(10.40 mg·kg~(-1)·d~(-1)) group. In addition, 10 C57BL/6J mice were included as the normal group. The mice in the normal group and model group were administrated with an equal volume of sterile distilled water, and those in other groups with corresponding agents by gavage once a day for 12 weeks. At the end of drug intervention, the levels of total cholesterol(TC), triglyceride(TG), high-density lipoprotein cholesterol(HDL-C), and low-density lipoprotein cholesterol(LDL-C) were measured by the biochemical method. Hematoxylin-eosin(HE) staining was employed to observe the plaque distribution in the aortic region. The serum levels of pro-inflammatory cytokines tumor necrosis factor-α(TNF-α) and interleukin(IL)-6 in M1 macrophages and anti-inflammatory cytokines IL-13 and IL-4 in M2 macrophages were determined by enzyme-linked immunosorbent assay(ELISA). The expression levels of inducible nitric oxide synthase(iNOS) and arginase-1(Arg-1) were examined by immunofluorescence. Real-time fluorescence quantitative polymerase chain reaction(real-time PCR) was employed to measure the mRNA levels of peroxisome proliferator-activated receptor γ(PPARγ), nuclear factor-κB(NF-κB), Arg-1, and iNOS in the aorta. Western blot was employed to determine the protein levels of PPARγ and NF-κB in the aorta. The results showed that compared with the normal group, the modeling elevated the TC, TG, and LDL-C levels, lowered the HDL-C level, caused large area thickening of the aortic intima, elevated the TNF-α and IL-6 levels, lowered the IL-4 and IL-13 levels, down-regulated the mRNA and protein levels of PPARγ and Arg-1, and up-regulated the mRNA and protein levels of iNOS and NF-κB in the aorta(P<0.01). Compared with the model group, low-, medium-, and high-dose Zhuyu Pills and atorvastatin calcium lowered the TC, TG, and LDL-C levels, elevated the HDL-C level, reduced the plaque area in a concentration-dependent manner, lowered the TNF-α and IL-6 levels, elevated the IL-4 and IL-13 levels, up-regulated the mRNA and protein levels of PPARγ and Arg-1, and down-regulated the mRNA and protein levels of NF-κB and iNOS in the aorta(P<0.05 or P<0.01). In conclusion, Zhuyu Pills may play an anti-atherosclerosis role by regulating PPARγ/NF-κB signaling pathway, inhibiting the polarization of macrophages toward the M1 phenotype, promoting the polarization of macrophages toward the M2 phenotype, and improving the inflammatory microenvironment of macrophages.

Identification of metabolic biomarkers of chronic vagus nerve stimulation (VNS) in subjects with drug-resistant epilepsy (DRE).

Neuromodulation by means of vagus nerve stimulation (VNS) therapy, reduces seizure frequency and improves quality of life in subjects with drug-resistant epilepsy (DRE), yet its molecular mechanism remains unclear. This study investigates the impact of chronic VNS on lipid bioactive metabolites and fatty acids (FA) in the plasma and red blood cells of seven subjects with DRE. By measuring expression levels of peroxisome proliferator-activated receptor α (PPARα) and sirtuin1 (SIRT1) genes-key regulators in energy and lipid metabolism-and lipid profiles before and after various stages of VNS, this study identifies potential mechanisms by which VNS may reduce seizure frequency. Blood samples collected before VNS device implantation, after acute VNS stimulus, and following gradual intensity increments up to therapeutic levels revealed that VNS increases SIRT1 and PPARα expression and erythrocyte concentrations of PPARα ligands. Additionally, we observe reduced de novo lipogenesis biomarkers in erythrocytes, indicating that VNS may influence systemic lipid and energy metabolism. Our findings suggest that VNS could enhance neuronal function by modulating energy metabolism, thus potentially reducing seizure frequency in subjects with DRE. Future research targeting SIRT1 and PPARα may provide innovative therapeutic strategies for managing DRE. Plain Language Summary: The exact mechanism of VNS is still unknown. This study investigated the effects of VNS Therapy on energetic metabolism, suggesting possible novel biomarkers for DRE subjects and neuromodulation therapies.

Lipid-Lowering Drug Gemfibrozil Protects Mice from Tay-Sachs Disease via Peroxisome Proliferator-Activated Receptor α.

Tay-Sachs disease (TSD) is a progressive heritable neurodegenerative disorder characterized by the deficiency of the lysosomal β-hexosaminidase enzyme (Hex-/-) and the storage of GM2 ganglioside, as well as other related glycoconjugates. Along with motor difficulties, TSD patients also manifest a gradual loss of skills and behavioral problems, followed by early death. Unfortunately, there is no cure for TSD; however, research on treatments and therapeutic approaches is ongoing. This study underlines the importance of gemfibrozil (GFB), an FDA-approved lipid-lowering drug, in inhibiting the disease process in a transgenic mouse model of Tay-Sachs. Oral administration of GFB significantly suppressed glial activation and inflammation, while also reducing the accumulation of GM2 gangliosides/glycoconjugates in the motor cortex of Tay-Sachs mice. Furthermore, oral GFB improved behavioral performance and increased the life expectancy of Tay-Sachs mice. While investigating the mechanism, we found that oral administration of GFB increased the level of peroxisome proliferator-activated receptor α (PPARα) in the brain of Tay-Sachs mice, and that GFB remained unable to reduce glycoconjugates and improve behavior and survival in Tay-Sachs mice lacking PPARα. Our results indicate a beneficial function of GFB that employs a PPARα-dependent mechanism to halt the progression of TSD and increase longevity in Tay-Sachs mice.

Inhibition of miR-96-5p alleviates intervertebral disc degeneration by regulating the peroxisome proliferator-activated receptor γ/nuclear factor-kappaB pathway

BackgroundIntervertebral disc degeneration (IDD) is the main pathogenesis of low back pain. MicroRNAs (miRNAs) have been found to exert regulatory function in IDD. This study aimed to investigate the effect and potential mechanism of miR-96-5p in IDD.MethodsIn vitro cell model of IDD was established by treating human nucleus pulposus cells (HNPCs) with interleukin-1β (IL-1β). The level of peroxisome proliferator-activated receptor γ (PPARγ) was examined in the IDD cell model by Western blot and quantification real-time reverse transcription-polymerase chain reaction (qRT-PCR). The expression level of miR-96-5p was detected by RT-qPCR. Effects of PPARγ or/and PPARγ agonist on inflammatory factors, extracellular matrix (ECM), apoptosis, and nuclear factor-kappaB (NF-κB) nuclear translocation were examined through enzyme-linked immunosorbent assay (ELISA), Western blot, flow cytometry assay, and immunofluorescence staining. The Starbase database and dual luciferase reporter assay were used to predict and validate the targeting relationship between miR-96-5p and PPARγ, and rescue assay was performed to gain insight into the role of miR-96-5p on IDD through PPARγ/NF-κB signaling.ResultsPPARγ expression reduced with concentration and time under IL-1β stimulation, while miR-96-5p expression showed the reverse trend (P < 0.05). Upregulation or/and activation of PPARγ inhibited IL-1β-induced the increase in inflammatory factor levels, apoptosis, degradation of the ECM, and the nuclear translocation of NF-κB (P < 0.05). MiR-96-5p was highly expressed but PPARγ was lowly expressed in IDD, while knockdown of PPARγ partially reversed remission of IDD induced by miR-96-5p downregulation (P < 0.05). MiR-96-5p promoted NF-κB entry into the nucleus but PPARγ inhibited this process.ConclusionInhibition of miR-96-5p suppressed IDD progression by regulating the PPARγ/NF-κB pathway. MiR-96-5p may be a promising target for IDD treatment clinically.

Inhibitory effect and mechanism of action of blue light irradiation on adipogenesis

Blue light can reach the epidermis, dermis, and hypodermis of the skin and affect the physiology of each cell type. However, thus far, most studies have focused on the effects of blue light on the epidermis and dermis; no studies have been conducted on the effects of blue light on the hypodermis. In this study, we attempted to elucidate the effects of blue light on the hypodermis. Specifically, we investigated the effects of blue light on 3T3-L1 adipogenesis and its mechanism of action. In this study, we found that blue light reduced lipid accumulation and GPDH activity, indicating its antiadipogenic properties. Furthermore, blue light inhibited the mRNA and protein levels of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes, such as Fasn and FABP4, and the luciferase activity of the PPRE promoter, suggesting that blue light downregulates the expression of adipogenic genes, leading to suppression of 3T3-L1 adipogenesis. Furthermore, blue light increased the phosphorylation of PPARγ, indicating its anti-adipogenic effect through PPARγ degradation. Blue light upregulates the expression and phosphorylation of transient receptor potential vanilloid 1 (TRPV1). Furthermore, blue light restored calcium influx, which was attenuated by adipogenesis. These data suggest that TRPV1 is involved in the anti-adipogenic effects of blue light. Blue light induced the phosphorylation of AMPK, ACC, and MAPKs, whereas capsazepine, an antagonist of TRPV1, attenuated the effects of blue light. Capsazepine treatment also reduced the blue light-induced anti-adipogenic effects. These results indicate that TRPV1 operates upstream of AMPK or MAPKs in the blue light-induced anti-adipogenesis process, which is mediated by activating the TRPV1-AMPK/MAPK signaling pathways. Meanwhile, inhibition of AMPK and MAPKs reduced the phosphorylation level of PPARγ, indicating that AMPK/MAPK signaling contributes to the phosphorylation of PPARγ. These results suggest the possibility of using blue light as an antiadipogenic agent.

Osteocalcin activates lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocyte

Fatty liver hemorrhage syndrome (FLHS) is the leading cause of noninfectious mortality in caged layers worldwide. Osteocalcin (OCN) is a protein secreted by osteoblasts, and its undercarboxylated form (ucOCN) acts as a multifunctional hormone that protects laying hens from FLHS. Lipophagy is a form of selective autophagy that breaks down lipid droplets (LDs) through lysosomes, and defective lipophagy is associated with FLHS. The aim of this study was to investigate the effects of ucOCN on the lipophagy of chicken embryonic hepatocytes and associated the function of the adiponectin (ADPN) signaling pathway. In this study, chicken embryonic hepatocytes were divided into 5 groups: control (CONT), fat emulsion (FE, 10% FE, v/v), FE with ucOCN at 1 ng/mL (FE-LOCN), 3 ng/mL (FE-MOCN), and 9 ng/mL (FE-HOCN). In addition, 4 μM AdipoRon, an adiponectin receptor agonist, was used to investigate the function of ADPN. The results showed that compared with CONT group, FE promoted the levels of phosphorylation of mammalian target of rapamycin (p-mTOR) (P < 0.05) and decreased the mRNA expression of ADNP receptors (AdipoR1 and AdipoR2). Compared with FE group, 3 and 9 ng/mL ucOCN inhibited the levels of autophagy adaptor p62 and p-mTOR (P < 0.05), increased the ratios of LC3-II/LC3-I (P < 0.05) and phosphorylated adenosine 5'-monophosphate-activated protein kinase (p-AMPK)/AMPK (P < 0.05), as well as the levels of peroxisome proliferator-activated receptor α (PPAR-α) and ADPN (P < 0.05). In addition, ucOCN at the tested concentrations increased the colocalization of LC3 and LDs in fatty hepatocytes. Administrated 4 μM AdipoRon activated AdipoR1 and AidpoR2 mRNA expression (P < 0.05), decreased the concentrations of triglyceride (P < 0.05), without effects on cell viability (P > 0.05). AdipoRon also increased the LC3-II/LC3-I ratio (P < 0.05) and the levels of p-AMPK/AMPK and PPAR-α (P < 0.05). In conclusion, the results reveal that ucOCN regulates lipid metabolism by activating lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocytes. The results may provide new insights for controlling FLHS in laying hens.

Subclinical ketosis leads to lipid metabolism disorder by downregulating the expression of acetyl-coenzyme A acetyltransferase 2 in dairy cows

Ketosis is a metabolic disease that often occurs in dairy cows postpartum and is a result of disordered lipid metabolism. Acetyl-coenzyme A (CoA) acetyltransferase 2 (ACAT2) is important for balancing cholesterol and triglyceride (TG) metabolism; however, its role in subclinical ketotic dairy cows is unclear. This study aimed to explore the potential correlation between ACAT2 and lipid metabolism disorders in subclinical ketotic cows through in vitro and in vivo experiments. In the in vivo experiment, liver tissue and blood samples were collected from healthy cows (CON, n = 6, β-hydroxybutyric acid [BHBA] concentration <1.0 mM) and subclinical ketotic cows (subclinical ketosis [SCK], n = 6, BHBA concentration = 1.2-3.0 mM) to explore the effect of ACAT2 on lipid metabolism disorders in SCK cows. For the in vitro experiment, bovine hepatocytes (BHEC) were used as the model. The effects of BHBA on ACAT2 and lipid metabolism were investigated via BHBA concentration gradient experiments. Subsequently, the relation between ACAT2 and lipid metabolism disorder was explored by transfection with siRNA of ACAT2. Transcriptomics showed an upregulation of differentially expression genes during lipid metabolism and significantly lower ACAT2 mRNA levels in the SCK group. Compared with the CON group in vivo, the SCK group showed significantly higher expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulator element binding protein 1c (SREBP1c) and significantly lower expression levels of peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyl-transferase 1A (CPT1A), sterol regulatory element binding transcription factor 2 (SREBP2), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Moreover, the SCK group had a significantly higher liver TG content and significantly lower plasma total cholesterol (TC) and free cholesterol content. These results were indicative of TG and cholesterol metabolism disorders in the liver of dairy cows with SCK. Additionally, the SCK group showed an increased expression of perilipin-2 (PLIN2), decreased expression of apolipoprotein B, and decreased plasma concentration of very low-density lipoproteins (VLDL) and low-density lipoproteins cholesterol (LDL-C) by downregulating ACAT2, which indicated an accumulation of TG in liver. In vitro experiments showed that BHBA induced an increase in the TG content of BHEC, decreased content TC, increased expression of PPARγ and SREBP1c, and decreased expression of PPARα, CPT1A, SREBP2, and HMGCR. Additionally, BHBA increased the expression of PLIN2 in BHEC, decreased the expression and fluorescence intensity of ACAT2, and decreased the VLDL and LDL-C contents. Furthermore, silencing ACAT2 expression increased the TG content; decreased the TC, VLDL, and LDL-C contents; decreased the expression of HMGCR and SREBP2; and increased the expression of SREBP1c; but had no effect on the expression of PLIN2. These results suggest that ACAT2 downregulation in BHEC promotes TG accumulation and inhibits cholesterol synthesis, leading to TG and cholesterol metabolic disorders. In conclusion, ACAT2 downregulation in the SCK group inhibited cholesterol synthesis, increased TG synthesis, and reduced the contents of VLDL and LDL-C, eventually leading to disordered TG and cholesterol metabolism.

Naringin may promote functional recovery following spinal cord injury by modulating microglial polarization through the PPAR-γ/NF-κB signaling pathway

ObjectiveThe flavonoid Naringin (Nar) has been extensively investigated and found to have multiple pharmacological properties, including neuroprotection. Although recent reports have shown that Nar can effectively treat spinal cord injury (SCI), its potential mechanism remains unknown. This study aimed to investigate the effects of Nar on motor recovery and inflammatory responses after SCI and to elucidate its mechanism. MethodsSCI rat models were established using Allen's weight-drop method. The rats were intragastrically given Nar (40 mg/kg) for 21 d, and their motor function before surgery and on the 1st, 3rd, 7th, 14th, 21st days after surgery was assessed by the Basso-Beattie-Bresnahan (BBB) scale and examined by the grid walking test (GWT). The enzyme linked immunosorbent assay (ELISA) was used to detect the interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1 levels in rat spinal cord tissues, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) to measure the mRNA expression levels of microglial activation markers CD68 and ionized calcium binding adaptor molecule 1 (Iba-1), M1 markers inducible nitric oxide synthase (iNOS) and IL-6, and M2 markers CD206 and Arginase 1 (Arg1). The expression levels of peroxisome proliferator-activated receptor gamma/nuclear factor kappa B (PPAR-γ/NF-κB) pathway-related proteins in rat spinal cord tissues were determined using western blotting. ResultsNar significantly increased the BBB score and decreased the mean error rate of GWT in SCI rats. Additionally, Nar effectively inhibited microglial activation and expression of M1 markers in spinal cord tissues. It also elevated M2 polarization-related gene expression and significantly lowered the levels of inflammatory factors. Further investigation showed that Nar enhanced the expression of PPAR-γ protein and inhibited NF-κB pathway activity. ConclusionNar promotes functional recovery by regulating microglial polarization and inhibiting the inflammatory response in SCI, and its mechanism may be related to the PPAR-γ/NF-κB signaling pathway activity.

Dietary apple polyphenols enhance mitochondrial turnover and respiratory chain enzymes.

Previous studies have demonstrated the beneficial effects of apple polyphenol (AP) intake on muscle endurance. Since mitochondria are critical for muscle endurance, we investigated mitochondrial enzyme activity, biogenesis, degradation and protein quality control. Twenty-four Wistar rats were randomly fed a 5% AP diet (5% AP group, n=8), a 0.5% AP diet (0.5% AP group, n=8), or a control diet (control group, n=8). After a 4-week feeding period, the expression level of peroxisome proliferator-activated receptor γ coactivator-1α, a mitochondrial biosynthetic factor, did not increase, whereas that of transcription factor EB, another regulator of mitochondrial synthesis, significantly increased. Moreover, the mitochondrial count did not differ significantly between the groups. In contrast, mitophagy-related protein levels were significantly increased. The enzymatic activities of mitochondrial respiratory chain complexes II, III and IV were significantly higher in the AP intake group than in the control group. We conclude that AP feeding increases the activity of respiratory chain complex enzymes in rat skeletal muscles. Moreover, mitochondrial biosynthesis and degradation may have increased in AP-treated rats. NEW FINDINGS: What is the central question of this study? Does the administration of apple polyphenols (AP) affect mitochondrial respiratory chain complex enzyme activity, biogenesis, degradation and protein quality control in rat skeletal muscles? What is the main finding and its importance? AP feeding increases respiratory chain complex enzyme activity in rat skeletal muscle. Moreover, AP administration increases transcription factor EB activation, and mitophagy may be enhanced to promote degradation of dysfunctional mitochondria, but mitochondrial protein quality control was not affected.

The effects of sodium butyrate supplementation on the expression levels of PGC-1α, PPARα, and UCP-1 genes, serum level of GLP-1, metabolic parameters, and anthropometric indices in obese individuals on weight loss diet: a study protocol for a triple-blind, randomized, placebo-controlled clinical trial

BackgroundObesity is a multifaceted disease characterized by an abnormal accumulation of adipose tissue. Growing evidence has proposed microbiota-derived metabolites as a potential factor in the pathophysiology of obesity and related metabolic conditions over the last decade. As one of the essential metabolites, butyrate affects several host cellular mechanisms related to appetite sensations and weight control. However, the effects of butyrate on obesity in humans have yet to be studied. Thus, the present study was aimed to evaluate the effects of sodium butyrate (SB) supplementation on the expression levels of peroxisome proliferator activated-receptor (PPAR) gamma coactivator-1α (PGC-1α), PPARα and uncoupling protein 1 (UCP1) genes, serum level of glucagon-like peptide (GLP1), and metabolic parameters, as well as anthropometric indices in obese individuals on a weight loss diet.MethodsThis triple-blind randomized controlled trial (RCT) will include 50 eligible obese subjects aged between 18 and 60 years. Participants will be randomly assigned into two groups: 8 weeks of SB (600 mg/day) + hypo-caloric diet or placebo (600 mg/day) + hypo-caloric diet. At weeks 0 and 8, distinct objectives will be pursued: (1) PGC-1α, PPARα, and UCP1 genes expression will be evaluated by real-time polymerase chain reaction; (2) biochemical parameters will be assayed using enzymatic methods; and (3) insulin and GLP1 serum level will be assessed by enzyme-linked immunosorbent assay kit.DiscussionNew evidence from this trial may help fill the knowledge gap in this realm and facilitate multi-center clinical trials with a substantially larger sample size.Trial registrationIranian Registry of Clinical Trials: IRCT20190303042905N2. Registered on 31 January 2021.

Ror1 promotes PPARα-mediated fatty acid metabolism in astrocytes.

Ror1 signaling regulates cell polarity, migration, proliferation, and differentiation during developmental morphogenesis, and plays an important role in regulating neurogenesis in the embryonic neocortices. However, the role of Ror1 signaling in the brains after birth remains largely unknown. Here, we found that expression levels of Ror1 in the mouse neocortices increase during the postnatal period, when astrocytes mature and start expressing GFAP. Indeed, Ror1 is highly expressed in cultured postmitotic mature astrocytes. RNA-Seq analysis revealed that Ror1 expressed in cultured astrocytes mediates upregulated expression of genes related to fatty acid (FA) metabolism, including the gene encoding carnitine palmitoyl-transferase 1a (Cpt1a), the rate-limiting enzyme of mitochondrial fatty acid β-oxidation (FAO). We also found that Ror1 promotes the degradation of lipid droplets (LDs) accumulated in the cytoplasm of cultured astrocytes after oleic acid loading, and that suppressed expression of Ror1 decreases the amount of FAs localized at mitochondria, intracellular ATP levels, and expression levels of peroxisome proliferator-activated receptor α (PPARα) target genes, including Cpt1a. Collectively, these findings indicate that Ror1 signaling promotes PPARα-mediated transcription of FA metabolism-related genes, thereby facilitating the availability of FAs derived from LDs for mitochondrial FAO in the mature astrocytes.

Adipokine chemerin overexpression in trophoblasts leads to dyslipidemia in pregnant mice: implications for preeclampsia

BackgroundThe adipokine chemerin regulates adipogenesis and the metabolic function of both adipocytes and liver. Chemerin is elevated in preeclamptic women, and overexpression of chemerin in placental trophoblasts induces preeclampsia-like symptoms in mice. Preeclampsia is known to be accompanied by dyslipidemia, albeit via unknown mechanisms. Here, we hypothesized that chemerin might be a contributor to dyslipidemia.MethodsSerum lipid fractions as well as lipid-related genes and proteins were determined in pregnant mice with chemerin overexpression in placental trophoblasts and chemerin-overexpressing human trophoblasts. In addition, a phospholipidomics analysis was performed in chemerin-overexpressing trophoblasts.ResultsOverexpression of chemerin in trophoblasts increased the circulating and placental levels of cholesterol rather than triglycerides. It also increased the serum levels of lysophosphatidic acid, high-density lipoprotein cholesterol (HDL-C), and and low-density lipoprotein cholesterol (LDL-C), and induced placental lipid accumulation. Mechanistically, chemerin upregulated the levels of peroxisome proliferator-activated receptor g, fatty acid-binding protein 4, adiponectin, sterol regulatory element-binding protein 1 and 2, and the ratio of phosphorylated extracellular signal-regulated protein kinase (ERK)1/2 / total ERK1/2 in the placenta of mice and human trophoblasts. Furthermore, chemerin overexpression in human trophoblasts increased the production of lysophospholipids and phospholipids, particularly lysophosphatidylethanolamine.ConclusionsOverexpression of placental chemerin production disrupts trophoblast lipid metabolism, thereby potentially contributing to dyslipidemia in preeclampsia.

Honokiol inhibits the inflammatory response and lipid metabolism disorder by inhibiting p38α in alcoholic liver disease.

Alcoholic liver disease (ALD) is one of the leading causes of liver-related morbidity and mortality worldwide, but effective treatments are still lacking. Honokiol, a lignin-type natural compound isolated from the leaves and bark of Magnolia plants, has been widely studied for its beneficial effects on several chronic diseases. Accumulating studies have revealed that honokiol displays a potential therapeutic effect on ALD. In this study, the protective activity of honokiol on ALD was confirmed due to its significant inhibitory activity on the expression level of inflammatory cytokines (such as TNF-α, IL-6 and IL-1β) in EtOH-fed mice and in EtOH-induced AML-12 cells. Meanwhile, the expression of the lipid metabolic parameter SREBP-1c was also reduced. However, PPAR-α was increased in animal and cell experiments, which indicated that the activity of honokiol was related to its regulated activity on lipid metabolism. The findings also showed that honokiol significantly inhibited the expression level of p38α in vivo and in vitro. Blocking p38α inhibited the expression levels of TNF-α, IL-6, IL-1β and SREBP-1c but promoted the expression of PPAR-α compared with the honokiol-treated group. Moreover, forced expression of p38α further produced the opposite effect on inflammatory cytokines and lipid metabolism indicators. p38α has been related to the activation of NF-κB. In our study, honokiol significantly inhibited the phosphorylation and activation of NF-κB-pIKKα mediated by p38α. In conclusion, the results suggest that honokiol may be an effective regulator of p38α by downregulating the NF-κB pathway, thereby reducing the inflammatory response and lipid metabolism disorder in ALD.

The Novel Inhibitory Effect of YM976 on Adipocyte Differentiation.

The pyrimidine derivative YM976 (4-(3-chlorophenyl)-1,7-diethylpyrido(2,3-d)-pyrimidin-2(1H)-one) exerts anti-inflammatory and anti-asthmatic effects. Considering that accumulation of lipids in adipose tissue is accompanied by inflammation, we investigated whether YM976 affects adipocyte differentiation. We found that YM976 significantly decreased lipid accumulation without cytotoxicity and reduced the expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα) as well as their lipogenic regulators including fatty acid synthase (FASN) and fatty acid-binding protein 4 (FABP4) in 3T3-L1 cells induced for differentiation. YM976 mainly inhibited the early stage of adipocyte differentiation. Furthermore, intracellular cAMP level was elevated by YM976 resulting in increased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). Conversely, decreasing the levels of AMPK or treatment with Compound C, an AMPK inhibitor, lessened the suppressive effects of YM976 on PPARγ transcriptional activity and adipogenesis. Thus, our results suggest YM976 as a novel potential compound for controlling lipid accumulation and formation of adipocytes in obesity.

PGC-1α in mediating mitochondrial biogenesis and intestinal epithelial differentiation promoted by purple potato extract

• Purple potato polyphenolic extract (PPE) promotes gut epithelial differentiation. • PPE upregulates PGC-1α and enhances mitochondria biogenesis in Caco-2 cells. • PPE promotes intracellular oxidative metabolism. • PGC-1α is indispensable in PPE-induced differentiation & mitochondrial biogenesis. Intestinal epithelial differentiation plays an important role in maintaining gut health and is impaired due to many diseases. Purple potatoes are rich in polyphenols that promote the differentiation of intestinal epithelial cells. In this study, we found that purple potato (PP) extract up-regulated the level of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α, the expression of mitochondrial-related enzymes, the content of mitochondrial DNA, and the levels of tricarboxylic acid cycle metabolites in human intestinal epithelial Caco-2 cells. Inhibition of PGC-1α by either PGC-1α inhibitor SR-18292 or siRNA-mediated knockdown eliminated the enhancing effects of PP extract on the expression of differentiation markers, mitochondrial metabolite contents and mitochondrial DNA copy number, as well as the expression of mitochondrial DNA-encoded enzymes. In summary, PP extract promoted mitochondrial biogenesis and the differentiation of intestinal epithelial cells, and these promotion effects are dependent on the activation of PGC-1α.

Cloning of goat PGAM2 gene and its overexpression promotes the differentiation of intramuscular preadipocytes

As a member of the PGAMs family, PGAM2 has been proved to catalyze the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. However, it is unclear whether PGAM2 has a role in regulating differentiation in goat intramuscular preadipocytes. Here, this study was carried to clone the open reading frame (ORF) of goat PGAM2, elucidate its molecular and expressional characteristics, and evaluate the involvement in adipogenesis of intramuscular preadipocytes. According to our findings, the cloned goat PGAM2 gene was 784 bp in full length, including 762 bp of ORF and encoding a protein of 253 amino acids. The expressional level of PGAM2 peaked at 48 hours after induced adipogenic differentiation and was highest in the skeletal muscle of triceps. Moreover, overexpression of PGAM2 transfected by its overexpression plasmid promotes lipid accumulation of goat intramuscular adipocyte as shown by Oil Red O and bodipy staining, accompanied by up-regulating the mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ) (p < 0.001), sterol regulatory element-binding protein 1 (SREBP1) (p < 0.001), CCAAT/Enhancer-binding protein α (C/EBPα) (p < 0.01) and lipoprotein lipase (LPL) (p < 0.01). Taken together, these findings indicate that PGAM2 is a positive regulator for goat intramuscular adipocytes and provide new insights into improvement intramuscular fat deposition in goat meat.

Taurine Attenuates Oxidized Fish Oil-Induced Oxidative Stress and Lipid Metabolism Disorder in Mice.

The objective of this study was to determine the effect of dietary taurine on lipid metabolism and liver injury in mice fed a diet high in oxidized fish oil. The ICR mice (six weeks old) were randomly assigned to six groups and fed different diets for 10 weeks: control (CON), normal plus 15% fresh fish oil diet (FFO), normal plus 15% oxidized fish oil diet (OFO), or OFO plus 0.6% (TAU1), 0.9% (TAU2) or 1.2% (TAU3) taurine. Compared to the CON group, OFO mice showed increased liver index, aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in serum (p < 0.05). In addition, OFO mice had increased cholesterol (CHOL)/high-density lipoprotein cholesterol (HDL-C) and decreased HDL-C/low-density lipoprotein cholesterol (LDL-C) and n-6/n-3 polyunsaturated fatty acid (PUFA) ratio in serum (p < 0.05) compared with CON mice. Notably, dietary taurine ameliorated the liver index and AST and MDA levels in serum and liver in a more dose-dependent manner than OFO mice. In addition, compared to OFO mice, decreased levels of CHOL and ratio of CHOL/HDL-C and n-6 PUFA/n-3 PUFA in serum were found in TAU3-fed mice. Supplementation with TAU2 and TAU3 increased the relative mRNA expression levels of peroxisome proliferator-activated receptor α, adipose triglyceride lipase, lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyl transferase 1 in liver compared with the OFO group (p < 0.05). Moreover, impaired autophagy flux was detected in mice fed with the OFO diet, and this was prevented by taurine. These findings suggested that dietary taurine might provide a potential therapeutic choice against oxidative stress and lipid metabolism disorder.