Role of UCP2 in the protective effects of PPARβ/δ activation on lipopolysaccharide-induced endothelial dysfunction

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's

Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.

Sinomenine alleviates lipopolysaccharide-induced acute lung injury via a PPARβ/δ-dependent mechanism

Evidence is mounting that sinomenine and peroxisome proliferator-activated receptor β/δ (PPARβ/δ) are effective against lipopolysaccharide (LPS)-induced acute lung injury (ALI) via anti-inflammatory properties. However, it is unknown whether PPARβ/δ plays a role in the protective effect of sinomenine on ALI. Here, we initially observed that preemptive administration of sinomenine markedly alleviated lung pathological changes, pulmonary edema and neutrophil infiltration, accompanied by inhibition of the expression of the pro-inflammatory cytokines Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6), which were largely reversed following the addition of a PPARβ/δ antagonist. Subsequently, we also noticed that sinomenine upregulated adenosine A_2A receptor expression in a PPARβ/δ-dependent manner in LPS-stimulated bone marrow-derived macrophages (BMDMs). Further investigation indicated that PPARβ/δ directly bound to the functional peroxisome proliferator responsive element (PPRE) in the adenosine A_2A receptor gene promoter region to enhance the expression of the adenosine A_2A receptor. Sinomenine was identified as a PPARβ/δ agonist. It could bind with PPARβ/δ, and promote the nuclear translocation and transcriptional activity of PPARβ/δ. In addition, combined treatment with sinomenine and an adenosine A_2A receptor agonist exhibited synergistic effects and better protective roles than their single use against ALI. Taken together, our results reveal that sinomenine exerts advantageous effects on ALI by activating of PPARβ/δ, with the subsequent upregulation of adenosine A_2A receptor expression, and provide a novel and potential therapeutic application for ALI.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

Activating PPARβ/δ Protects against Endoplasmic Reticulum Stress-Induced Astrocytic Apoptosis via UCP2-Dependent Mitophagy in Depressive Model

As energy metabolism regulation factor, peroxisome proliferator-activated receptor (PPAR) is thought to be a potential target for the treatment of depression. The present study was performed to evaluate the effects of activating PPARβ/δ, the most highly expressed subtype in the brain, in depressive in vivo and in vitro models. We observed that PPARβ/δ agonist GW0742 significantly alleviated depressive behaviors in mice and promoted the formation of autophagosomes around the damaged mitochondria in hippocampal astrocytes. Our in vitro experiments showed that GW0742 could reduce mitochondrial oxidative stress, and thereby attenuate endoplasmic reticulum (ER) stress-mediated apoptosis pathway via inhibiting IRE1α phosphorylation, subsequently protect against astrocytic apoptosis and loss. Furthermore, we found that PPARβ/δ agonist induces astrocytic mitophagy companied with the upregulated UCP2 expressions. Knocking down UCP2 in astrocytes could block the anti-apoptosis and pro-mitophagy effects of GW0742. In conclusion, our findings reveal PPARβ/δ activation protects against ER stress-induced astrocytic apoptosis via enhancing UCP2-mediated mitophagy, which contribute to the anti-depressive action. The present study provides a new insight for depression therapy.

Bacillus subtilis inhibits intestinal inflammation and oxidative stress by regulating gut flora and related metabolites in laying hens

Bacillus subtilis is one of the most popular commercial probiotics used in farm animal production. However, its potential mechanisms are not very clear. The aim of this study was to investigate the effects of dietary Bacillus subtilis on intestinal histomorphology, innate immunity, microbiota composition, transcriptomics, and related metabolomics. Twenty-four 48-week-old Lohman Pink-shell laying hens were randomly divided into two groups: a basic diet and the basic diet supplemented with Bacillus subtilis (0.5 g/kg) for a 9-week experiment. At the end of the experiment, tissues of the duodenum, ileum, and jejunum as well as cecal content of each bird were collected for microstructure, PCR, transcriptome, metabolome, and 16S rRNA analyses. The results showed that dietary Bacillus subtilis supplement had no effect on the intestinal microstructure. However, Bacillus subtilis increased mRNA expression of tight junction protein occludin (P < 0.05), while reduced mRNA expression of lipopolysaccharide-induced TNF factor (P < 0.01) in the duodenum. Moreover, transcriptomic results indicated that most of Bacillus subtilis supplement-induced differential genes were associated with inflammation and immunity, including cytochrome b-245 beta chain, transferrin, and purinergic receptor P2X 7, resulting in a decrease in Malondialdehyde level (P < 0.05) in the duodenum. In addition, at the genus level, Bacillus subtilis supplement enriched the potential beneficial bacteria, Candidatus_Soleaferrea (P = 0.02) but inhibited the harmful bacteria including Lachnospiraceae_FCS020_group, Ruminiclostridium, Lachnospiraceae_UCG-010, and Oxalobacter. Metabolomic results revealed that N-Acetylneuraminic acid and ADP were increased by fed Bacillus subtilis. These results suggest that dietary Bacillus subtilis could inhibit gut inflammation and improve antioxidative status and barrier integrity of the duodenum via regulating gut microbial composition in laying hens.

PPAR control of metabolism and cardiovascular functions

Peroxisome proliferator-activated receptor-α (PPARα), PPARδ and PPARγ are transcription factors that regulate gene expression following ligand activation. PPARα increases cellular fatty acid uptake, esterification and trafficking, and regulates lipoprotein metabolism genes. PPARδ stimulates lipid and glucose utilization by increasing mitochondrial function and fatty acid desaturation pathways. By contrast, PPARγ promotes fatty acid uptake, triglyceride formation and storage in lipid droplets, thereby increasing insulin sensitivity and glucose metabolism. PPARs also exert antiatherogenic and anti-inflammatory effects on the vascular wall and immune cells. Clinically, PPARγ activation by glitazones and PPARα activation by fibrates reduce insulin resistance and dyslipidaemia, respectively. PPARs are also physiological master switches in the heart, steering cardiac energy metabolism in cardiomyocytes, thereby affecting pathological heart failure and diabetic cardiomyopathy. Novel PPAR agonists in clinical development are providing new opportunities in the management of metabolic and cardiovascular diseases.

Role of haematopoietic cell-specific protein 1-associated protein X-1 gene in lipopolysaccharide-induced apoptosis of human dermal fibroblasts

Wound healing may be disrupted by lipopolysaccharide (LPS)-induced mitochondrial dysfunction, inflammation, and excessive oxidative stress, which can lead to undesirable consequences. The haematopoietic cell-specific protein 1-associated protein X-1 (HAX-1) is a mitochondrial matrix protein that regulates mitochondrial function. This study aimed to comprehensively identify the role of HAX-1 in the inhibition of LPS-induced mitochondrial dysfunction and apoptosis in human dermal fibroblasts (HDFs). HAX-1 expression was assessed in the HDF-a cell line using real-time polymerase chain reaction, western blotting, and immunohistochemical staining. The viability, migration, and apoptosis of HDF-a cells were evaluated using the water-soluble tetrazolium-1 assay, transwell assay, and flow cytometry analysis, respectively. Mitochondrial function was evaluated based on reactive oxygen species (ROS) generation and mitochondrial membrane potential (ΔΨm). Our results demonstrated that LPS stimulation markedly repressed HAX-1 expression in HDFs and silencing of HAX-1 led to mitochondrial ROS accumulation, ΔΨm disruption, and abnormal mitochondrial morphology. Accordingly, overexpression of HAX-1 or administration of metformin enhanced mitochondrial fusion and normalized mitochondrial dynamics, thereby reversing LPS-induced mitochondrial dysfunction, fibroblast apoptosis, and viability and migration inhibition in HDF-a cells. These data support a mechanism wherein HAX-1 plays a crucial role in LPS-induced fibroblast apoptosis in a mitochondria-dependent manner.

Peroxisome Proliferator-Activated Receptors (PPARs) and Oxidative Stress in Physiological Conditions and in Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor superfamily. Originally described as “orphan nuclear receptors”, they can bind both natural and synthetic ligands acting as agonists or antagonists. In humans three subtypes, PPARα, β/δ, γ, are encoded by different genes, show tissue-specific expression patterns, and contribute to the regulation of lipid and carbohydrate metabolisms, of different cell functions, including proliferation, death, differentiation, and of processes, as inflammation, angiogenesis, immune response. The PPAR ability in increasing the expression of various antioxidant genes and decreasing the synthesis of pro-inflammatory mediators, makes them be considered among the most important regulators of the cellular response to oxidative stress conditions. Based on the multiplicity of physiological effects, PPAR involvement in cancer development and progression has attracted great scientific interest with the aim to describe changes occurring in their expression in cancer cells, and to investigate the correlation with some characteristics of cancer phenotype, including increased proliferation, decreased susceptibility to apoptosis, malignancy degree and onset of resistance to anticancer drugs. This review focuses on mechanisms underlying the antioxidant and anti-inflammatory properties of PPARs in physiological conditions, and on the reported beneficial effects of PPAR activation in cancer.

Uncoupling protein 2 and dynamin-related protein 1 mRNA expressions as genetic markers for plaque psoriasis

BACKGROUND

Psoriasis is a long-lasting, inflammatory disease of the skin with not fully understood pathogenesis. Uncoupling protein 2 (UCP2) and dynamin-related protein 1 (Drp1) are the main mitochondrial regulatory proteins implicated in various inflammatory conditions. This work aimed to evaluate the role of UCP2 and Drp1 messenger RNA (mRNA) expressions in diagnosing plaque psoriasis and to correlate their expression levels with the available clinical data.

METHODS

Total number of 210 subjects (105 plaque psoriasis patients and 105 healthy volunteers) was enrolled in the current study. Plasma UCP2 and Drp1 mRNA relative expressions were studied by real-time polymerase chain reaction technique.

RESULTS

A significant statistical decrease in the expression levels of the mitochondrial regulatory proteins UCP2 and Drp1 mRNA in plasma of patient group in comparison to control subjects (P < 0.001). UCP2 mRNA expression was significantly correlated with the onset of disease and scalp affection (P < 0.05). The receiver operating characteristic (ROC) curve was the test used for verification of the accuracy of UCP2 and Drp1 mRNA expressions in identifying cases from healthy control subjects; UCP2 mRNA expression had a greater percent of accuracy (94%), sensitivity (97%), and specificity (87%) than Drp1 mRNA expression.

CONCLUSIONS

Although UCP2 and Drp1 mRNA are downregulated in plasma of psoriatic patients, UCP2 could serve better as a promising marker for plaque psoriasis. Despite developments in the treatment of psoriasis, these results provide new insights in disease pathogenesis suggesting UCP2 may be a good target for treatment.

lncRNA RMRP Prevents Mitochondrial Dysfunction and Cardiomyocyte Apoptosis via the miR-1-5p/hsp70 Axis in LPS-Induced Sepsis Mice

Both long non-coding RNA (lncRNA) RMRP and heat shock protein (HSP) 70 have been known to play crucial roles in inflammation. The present study investigated the roles of lncRNA RMRP and HSP70 protein 4 (HSPA4) in lipopolysaccharide (LPS)-induced sepsis. The C57BL/6 mice were treated with LPS, following which the cardiomyocytes were isolated for in vitro experiments. Further, a cardiac muscle cell line, HL-1 was transfected with plasmids expressing RMRP and HSPA4, si-NC, si-HSPA4, miR-1-5p mimic, and controls in vitro. Cell apoptosis, mitochondrial membrane potential (MMP), and levels of intracellular reactive oxygen species (ROS), mRNAs, and proteins were detected in the transfected mice tissues and cells. The LPS treatment significantly reduced the expression levels of RMRP, MMP, and mitochondrial cytochrome C. Moreover, it enhanced the cardiomyocyte apoptosis, intracellular ROS levels, cytoplasm cytochrome C levels, and the expression of caspase-3 and caspase-9 and nuclear factor κB (NF-κB) p65 subunit. The predicted RMRP-miR-1-5p-HSPA4 network was validated by co-transfection experiments in vitro in HL-1 cells. The transfection of miR-1-5p-treated cells with pcDNA-RMRP enhanced the levels of the protein HSPA4; however, no change at the mRNA level was observed. Moreover, miR-1-5p mimic attenuated the protective effect of pcDNA-HSPA4 against LPS-induced mitochondrial damage and apoptosis. In addition, we observed that silencing of HSPA4 increased the expression of nuclear p65; however, this effect could be reversed by co-transfection with pcDNA-RMRP. The lncRNA RMRP axis acts as a sponge for miR-1-5p. RMRP inhibits LPS-induced apoptosis of cardiomyocytes and mitochondrial damage by suppressing the post-transcriptional regulatory function of miR-1-5p on HSPA4. We believe that RMRP exhibits therapeutic potential for LPS-induced myocardial dysfunction both in vitro and in vivo.

Link between microbiota and hypertension: Focus on LPS/TLR4 pathway in endothelial dysfunction and vascular inflammation, and therapeutic implication of probiotics

High blood pressure (BP) presents a significant public health challenge. Recent findings suggest that altered microbiota can exert a hypertensive effect on the host. One of the possible mechanisms involved is the chronic translocation of its components, mainly lipopolysaccharides (LPS) into systemic circulation leading to metabolic endotoxemia. In animal models, LPS has been commonly used to induce endothelial dysfunction and vascular inflammation. In human studies, plasma LPS concentration has been positively correlated with hypertension, however, the mechanistic link has not been fully elucidated. It is hypothesised here that the LPS-induced direct alterations to the vascular endothelium and resulting hypertension are possible targets for probiotic intervention. The methodology of this review involved a systematic search of the literature with critical appraisal of papers. Three tranches of search were performed: 1) existing review papers; 2) primary mechanistic animal, in vitro and human studies; and 3) primary intervention studies. A total of 70 peer-reviewed papers were included across the three tranches and critically appraised using SIGN50 for human studies and the ARRIVE guidelines for animal studies. The extracted information was coded into key themes and summarized in a narrative analysis. Results highlight the role of LPS in the activation of endothelial toll-like receptor 4 (TLR4) initiating a cascade of interrelated signalling pathways including: 1) Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/ Reactive oxygen species (ROS)/ Endothelial nitric oxide synthase (eNOS) pathway leading to endothelial dysfunction; and 2) Mitogen-Activated Protein Kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways leading to vascular inflammation. Findings from animal intervention studies suggest an improvement in vasorelaxation, vascular inflammation and hypertension following probiotic supplementation, which was mediated by downregulation of LPS-induced pathways. Randomised controlled trials (RCTs) and systematic reviews provided some evidence for the anti-inflammatory effect of probiotics with statistically significant antihypertensive effect in clinical samples and may offer a viable intervention for the management of hypertension.

Uncoupling Protein 2 Increases Blood Pressure in DJ -1 Knockout Mice

Background The redox-sensitive chaperone DJ -1 and uncoupling protein 2 are protective against mitochondrial oxidative stress. We previously reported that renal-selective depletion and germline deletion of DJ -1 increases blood pressure in mice. This study aimed to determine the mechanisms involved in the oxidative stress-mediated hypertension in DJ -1 ^-/- mice. Methods and Results There were no differences in sodium excretion, renal renin expression, renal NADPH oxidase activity, and serum creatinine levels between DJ -1 ^-/- and wild-type mice. Renal expression of nitro-tyrosine, malondialdehyde, and urinary kidney injury marker-1 were increased in DJ -1 ^-/- mice relative to wild-type littermates. mRNA expression of mitochondrial heat shock protein 60 was also elevated in kidneys from DJ -1 ^-/- mice, indicating the presence of oxidative stress. Tempol-treated DJ -1 ^-/- mice presented higher serum nitrite/nitrate levels than vehicle-treated DJ -1 ^-/- mice, suggesting a role of the NO system in the high blood pressure of this model. Tempol treatment normalized renal kidney injury marker-1 and malondialdehyde expression as well as blood pressure in DJ -1 ^-/- mice, but had no effect in wild-type mice. The renal Ucp2 mRNA expression was increased in DJ -1 ^-/- mice versus wild-type and was also normalized by tempol. The renal-selective silencing of Ucp2 led to normalization of blood pressure and serum nitrite/nitrate ratio in DJ -1 ^-/- mice. Conclusions The deletion of DJ -1 leads to oxidative stress-induced hypertension associated with downregulation of NO function, and overexpression of Ucp2 in the kidney increases blood pressure in DJ -1 ^-/- mice. To our knowledge, this is the first report providing evidence of the role of uncoupling protein 2 in blood pressure regulation.

The metabolic and vascular protective effects of olive (Olea europaea L.) leaf extract in diet-induced obesity in mice are related to the amelioration of gut microbiota dysbiosis and to its immunomodulatory properties

INTRODUCTION

Many studies have showed the beneficial effects of the olive (Olea europaea) leaf extract (OLE) in experimental models of metabolic syndrome, which have been ascribed to the presence of phenolic compounds, like oleuropeoside. This study evaluated the effects of a chemically characterized OLE in high fat diet (HFD)-induced obesity in mice, describing the underlying mechanisms involved in the beneficial effects, with special attention to vascular dysfunction and gut microbiota composition.

METHODS

C57BL/6J mice were distributed in different groups: control, control-treated, obese and obese-treated with OLE (1, 10 and 25 mg/kg/day). Control mice received a standard diet, whereas obese mice were fed HFD. The treatment was followed for 5 weeks, and animal body weight periodically assessed. At the end of the treatment, metabolic plasma analysis (including lipid profile) as well as glucose and insulin levels were performed. The HFD-induced inflammatory status was studied in liver and fat, by determining the RNA expression of different inflammatory mediators by qPCR; also, different markers of intestinal epithelial barrier function were determined in colonic tissue by qPCR. Additionally, flow cytometry of immune cells from adipose tissue, endothelial dysfunction in aortic rings as well as gut microbiota composition were evaluated. Faecal microbiota transplantation (FMT) to antibiotic-treated mice fed with HFD was performed.

RESULTS

OLE administration reduced body weight gain, basal glycaemia and insulin resistance, and showed improvement in plasma lipid profile when compared with HFD-fed mice. The extract significantly ameliorated the HFD-induced altered expression of key adipogenic genes, like PPARs, adiponectin and leptin receptor, in adipose tissue. Furthermore, the extract reduced the RNA expression of Tnf-α, Il-1β, Il-6 in liver and adipose tissue, thus improving the tissue inflammatory status associated to obesity. The flow cytometry analysis in adipose tissue corroborated these observations. Additionally, the characterization of the colonic microbiota by sequencing showed that OLE administration was able to counteract the dysbiosis associated to obesity. The extract reversed the endothelial dysfunction observed in the aortic rings of obese mice. FMT from donors HFD-OLE to recipient mice fed an HFD prevented the development of obesity, glucose intolerance, insulin resistance and endothelial dysfunction.

CONCLUSION

OLE exerts beneficial effects in HFD-induced obesity in mice, which was associated to an improvement in plasma and tissue metabolic profile, inflammatory status, gut microbiota composition and vascular dysfunction.

Mitochondrial dysfunction in affected skin and increased mitochondrial DNA in serum from patients with psoriasis

Psoriasis is characterized by keratinocyte proliferation and chronic inflammation, but the pathogenesis is still unclear. Dysregulated mitochondria (mt) could lead to reduced apoptosis and extracellular secretion of mtDNA, acting as "innate pathogen" triggering inflammation. Serum was obtained from healthy volunteers and psoriatic patients. Mitochondrial DNA was extracted from the serum and amplified with quantitative PCR (qPCR). Punch biopsies were obtained from lesional and non-lesional psoriatic skin (10 cm apart) and from healthy volunteers, were placed in RNA later and were stored at -80°C until RNA was extracted and cDNA was synthesized; gene expression of uncoupling protein 2 (UCP2), Dynamin-related protein 1 (Drp1) and calcineurin, involved in the regulation of mitochondria function, was detected with qPCR. Mitochondrial DNA was significantly increased (7s, P = 0.0496 and Cytochrome B, CytB, P = 0.0403) in the serum of psoriatic patients (n = 63) as compared to controls (n = 27). Gene expression was significantly reduced for UCP2 (P = 0.0218), Drp1 (P = 0.0001) and calcineurin (P = 0.0001) in lesional psoriatic skin, as compared to non-lesional or control skin. Increased serum extracellular mtDNA in psoriatic patients and decreased expression of mitochondrial regulatory proteins in psoriatic skin suggest increased inflammation and reduced keratinocyte apoptosis, respectively. Inhibitors of mtDNA secretion and/or UCP2 stimulants may be potential treatment options.

Exercise ameliorates endoplasmic reticulum stress-mediated vascular dysfunction in mesenteric arteries in atherosclerosis

Endoplasmic reticulum (ER) stress is closely associated with atherosclerosis, but the effects of exercise on ER stress-mediated endothelial dysfunction in atherosclerosis is not yet fully understood. We assessed endothelium-dependent vasodilation in isolated mesenteric arteries from wild type (WT), WT with exercise (WT-EX), ApoE knockout (ApoE KO), and ApoE KO mice with exercise (ApoE KO-EX). Vasodilation to acetylcholine (ACh) was elicited in the presence of inhibitors of ER stress, eNOS, caspase-1, and UCP-2 (Tudca, L-NAME, AC-YVARD-cmk, and Genipin, respectively) and the ER stress inducer (Tunicamycin). Immunofluorescence was used to visualize the expression of CHOP, as an indicator of ER stress, in superior mesenteric arteries (SMA). Dilation to ACh was attenuated in ApoE KO but was improved in ApoE KO-EX. Incubation of Tudca and AC-YVARD-cmk improved ACh-induced vasodilation in ApoE KO. L-NAME, tunicamycin, and Genipin attenuated vasodilation in WT, WT-EX and ApoE KO-EX, but not in ApoE KO. Exercise training reversed the increase in CHOP expression in the endothelium of SMA of ApoE KO mice. We conclude that ER stress plays a significant role in endothelial dysfunction of resistance arteries in atherosclerosis and that exercise attenuates ER stress and regulates its critical downstream signaling pathways including eNOS, UCP-2 and caspase-1.

Partitioning of adipose lipid metabolism by altered expression and function of PPAR isoforms after bariatric surgery

BACKGROUND

Bariatric surgery remains the most effective treatment for reducing adiposity and eliminating type 2 diabetes; however, the mechanism(s) responsible have remained elusive. Peroxisome proliferator-activated receptors (PPAR) encompass a family of nuclear hormone receptors that upon activation exert control of lipid metabolism, glucose regulation and inflammation. Their role in adipose tissue following bariatric surgery remains undefined.

MATERIALS AND METHODS

Subcutaneous adipose tissue biopsies and serum were obtained and evaluated from time of surgery and on postoperative day 7 in patients randomized to Roux-en-Y gastric bypass (n=13) or matched caloric restriction (n=14), as well as patients undergoing vertical sleeve gastrectomy (n=33). Fat samples were evaluated for changes in gene expression, protein levels, β-oxidation, lipolysis and cysteine oxidation.

RESULTS

Within 7 days, bariatric surgery acutely drives a change in the activity and expression of PPARγ and PPARδ in subcutaneous adipose tissue thereby attenuating lipid storage, increasing lipolysis and potentiating lipid oxidation. This unique metabolic alteration leads to changes in downstream PPARγ/δ targets including decreased expression of fatty acid binding protein (FABP) 4 and stearoyl-CoA desaturase-1 (SCD1) with increased expression of carnitine palmitoyl transferase 1 (CPT1) and uncoupling protein 2 (UCP2). Increased expression of UCP2 not only facilitated fatty acid oxidation (increased 15-fold following surgery) but also regulated the subcutaneous adipose tissue redoxome by attenuating protein cysteine oxidation and reducing oxidative stress. The expression of UCP1, a mitochondrial protein responsible for the regulation of fatty acid oxidation and thermogenesis in beige and brown fat, was unaltered following surgery.

CONCLUSIONS

These results suggest that bariatric surgery initiates a novel metabolic shift in subcutaneous adipose tissue to oxidize fatty acids independently from the beiging process through regulation of PPAR isoforms. Further studies are required to understand the contribution of this shift in expression of PPAR isoforms to weight loss following bariatric surgery.

Role of endoplasmic reticulum stress in the protective effects of PPARβ/δ activation on endothelial dysfunction induced by plasma from patients with lupus

Background

We tested whether GW0742, a peroxisome proliferator-activated receptor beta/delta (PPARβ/δ) agonist, improves endothelial dysfunction induced by plasma from patients with systemic lupus erythematosus (SLE) involving the inhibition of endoplasmic reticulum (ER) stress.

Methods

A total of 12 non-pregnant women with lupus and 5 non-pregnant healthy women (controls) participated in the study. Cytokines and double-stranded DNA autoantibodies (anti-dsDNA) were tested in plasma samples. Endothelial cells, isolated from human umbilical cord veins (HUVECs), were used to measure nitric oxide (NO), intracellular reactive oxygen species (ROS) production, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, and ER stress markers.

Results

Interferon-γ, interleukin-6, and interleukin-12 levels were significantly increased in plasma from patients with SLE with active nephritis (AN), as compared to both patients with SLE with inactive nephritis (IN) and the control group. The NO production stimulated by both the calcium ionophore A23187 and insulin was significantly reduced in HUVECs incubated with plasma from patients with AN-SLE as compared with the control group. Plasma from patients with IN-SLE did not modify A23187-stimulated NO production. Increased ROS production and NADPH oxidase activity were found in HUVECs incubated with plasma from patients with AN-SLE, which were suppressed by the ER stress inhibitor 4-PBA and the NADPH oxidase inhibitors, apocynin and VAS2870. GW0742 incubation restored the impaired NO production, the increased ROS levels, and the increased ER stress markers induced by plasma from patients with AN-SLE. These protective effects were abolished by the PPARβ/δ antagonist GSK0660 and by silencing PPARβ/δ.

Conclusions

PPARβ/δ activation may be an important target to control endothelial dysfunction in patients with SLE.

UCP-2 is involved in angiotensin-II-induced abdominal aortic aneurysm in apolipoprotein E-knockout mice

UCP-2 shows an important role in modulating of mitochondrial membrane potential and cell apoptosis. Whether or not UCP-2 could been a critical factor in preventing AAA formation is not known. We report that UCP-2 protein and mRNA expression were significantly higher in Ang-Ⅱ-induced AAA of mice. The incident rate of AAA in UCP-2-/-ApoE-/- mice after Ang-Ⅱtreatment was higher than the rate in the UCP-2+/+ApoE-/- mice. The abdominal aorta from UCP-2-/-ApoE-/- mice showed the medial hypertrophy, fragmentation of elastic lamellas and depletion of α-SMA. The NADPH oxidase activity and level of MDA was significantly higher in UCP-2-/-ApoE-/- mice than UCP-2+/+ApoE-/- or WT mice. Besides, the SOD activity is increased in UCP-2+/+ApoE-/- mice as compared with WT mice, whereas deficiency of UCP-2 decreased the increasing SOD activity in Ang-Ⅱ treated ApoE-/- mice. UCP-2 knockout up-regulated the MMP2 and MMP9 expression in aortic aneurysm. Ang-Ⅱ induced apoptosis of VSMCs was increased in UCP-2-/-ApoE-/- mice. And the expression of eNOS in vascular tissue from UCP-2-/-ApoE-/- mice is lower than WT and UCP-2+/+ApoE-/- mice. This study provides a mechanism by which UCP-2, via anti-oxidants and anti-apoptosis, participates in the preventing of AAA formation.

Activation of Peroxisome Proliferator Activator Receptor β/δ Improves Endothelial Dysfunction and Protects Kidney in Murine Lupus

Women with systemic lupus erythematosus exhibit a high prevalence of hypertension, endothelial dysfunction, and renal injury. We tested whether GW0742, a peroxisome proliferator activator receptor β/δ (PPARβ/δ) agonist, ameliorates disease activity and cardiovascular complications in a female mouse model of lupus. Thirty-week-old NZBWF1 (lupus) and NZW/LacJ (control) mice were treated with GW0742 or with the PPARβ/δ antagonist GSK0660 plus GW0742 for 5 weeks. Blood pressure, plasma double-stranded DNA autoantibodies and cytokines, nephritis, hepatic opsonins, spleen lymphocyte populations, endothelial function, and vascular oxidative stress were compared in treated and untreated mice. GW0742 treatment reduced lupus disease activity, blood pressure, cardiac and renal hypertrophy, splenomegaly, albuminuria, and renal injury in lupus mice, but not in control. GW0742 increased hepatic opsonins mRNA levels in lupus mice and reduced the elevated T, B, Treg, and Th1 cells in spleens from lupus mice. GW0742 lowered the higher plasma concentration of proinflammatory cytokines observed in lupus mice. Aortae from lupus mice showed reduced endothelium-dependent vasodilator responses to acetylcholine and increased nicotinamide adenine dinucleotide phosphate oxidase-driven vascular reactive oxygen species production, which were normalized by GW0742 treatment. All these effects of GW0742 were inhibited by PPARβ/δ blockade with GSK0660. Pharmacological activation of PPARβ/δ reduced hypertension, endothelial dysfunction, and organ damage in severe lupus mice, which was associated with reduced plasma antidouble-stranded DNA autoantibodies and anti-inflammatory and antioxidant effects in target tissues. Our findings identify PPARβ/δ as a promising target for an alternative approach in the treatment of systemic lupus erythematosus and its associated vascular damage.

Antihypertensive effects of peroxisome proliferator-activated receptor-β/δ activation

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors, which is composed of three members encoded by distinct genes: PPARα, PPARβ/δ, and PPARγ. The biological actions of PPARα and PPARγ and their potential as a cardiovascular therapeutic target have been extensively reviewed, whereas the biological actions of PPARβ/δ and its effectiveness as a therapeutic target in the treatment of hypertension remain less investigated. Preclinical studies suggest that pharmacological PPARβ/δ activation induces antihypertensive effects in direct [spontaneously hypertensive rat (SHR), ANG II, and DOCA-salt] and indirect (dyslipemic and gestational) models of hypertension, associated with end-organ damage protection. This review summarizes mechanistic insights into the antihypertensive effects of PPARβ/δ activators, including molecular and functional mechanisms. Pharmacological PPARβ/δ activation induces genomic actions including the increase of regulators of G protein-coupled signaling (RGS), acute nongenomic vasodilator effects, as well as the ability to improve the endothelial dysfunction, reduce vascular inflammation, vasoconstrictor responses, and sympathetic outflow from central nervous system. Evidence from clinical trials is also examined. These preclinical and clinical outcomes of PPARβ/δ ligands may provide a basis for the development of therapies in combating hypertension.