Troglitazone antagonizes tumor necrosis factor-alpha-induced reprogramming of adipocyte gene expression by inhibiting the transcriptional regulatory functions of NF-kappaB

Polygalacic acid attenuates cognitive impairment by regulating inflammation through PPARγ/NF-κB signaling pathway

AIMS

We aimed to explore the role and molecular mechanism of polygalacic acid (PA) extracted from traditional Chinese medicine Polygala tenuifolia in the treatment of Alzheimer's disease (AD).

METHODS

The network pharmacology analysis was used to predict the potential targets and pathways of PA. Molecular docking was applied to analyze the combination between PA and core targets. Aβ42 oligomer-induced AD mice model and microglia were used to detect the effect of PA on the release of pro-inflammatory mediators and its further mechanism. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of PA on activating microglia-mediated neuronal apoptosis.

RESULTS

We predict that PA might regulate inflammation by targeting PPARγ-mediated pathways by using network pharmacology. In vivo study, PA could attenuate cognitive deficits and inhibit the expression levels of inflammation-related factors. In vitro study, PA can also decrease the production of activated microglia-mediated inflammatory cytokines and reduce the apoptosis of N2a neuronal cells. PPARγ inhibitor GW9662 inversed the neuroprotective effect of PA. Both in vivo and in vitro studies showed PA might attenuate the inflammation through the PPARγ/NF-κB pathway.

CONCLUSIONS

PA is expected to provide a valuable candidate for new drug development for AD in the future.

The Effect of an Innovative Combination of Bergamot Polyphenolic Fraction and Cynara cardunculus L. Extract on Weight Gain Reduction and Fat Browning in Obese Mice

Obesity is one of the world's most serious public health issues, with a high risk of developing a wide range of diseases. As a result, focusing on adipose tissue dysfunction may help to prevent the metabolic disturbances commonly associated with obesity. Nutraceutical supplementation may be a crucial strategy for improving WAT inflammation and obesity and accelerating the browning process. The aim of this study was to perform a preclinical "proof of concept" study on Bergacyn®, an innovative formulation originating from a combination of bergamot polyphenolic fraction (BPF) and Cynara cardunculus (CyC), for the treatment of adipose tissue dysfunction. In particular, Bergacyn® supplementation in WD/SW-fed mice at doses of 50 mg/kg given orally for 12 weeks, was able to reduce body weight and total fat mass in the WD/SW mice, in association with an improvement in plasma biochemical parameters, including glycemia, total cholesterol, and LDL levels. In addition, a significant reduction in serum ALT levels was highlighted. The decreased WAT levels corresponded to an increased weight of BAT tissue, which was associated with a downregulation of PPARγ as compared to the vehicle group. Bergacyn® was able to restore PPARγ levels and prevent NF-kB overexpression in the WAT of mice fed a WD/SW diet, suggesting an improved oxidative metabolism and inflammatory status. These results were associated with a significant potentiation of the total antioxidant status in WD/SW mice. Finally, our data show, for the first time, that Bergacyn® supplementation may be a valuable approach to counteract adipose tissue dysfunction and obesity-associated effects on cardiometabolic risk.

A Functional Variant Alters the Binding of Bone morphogenetic protein 2 to the Transcription Factor NF-κB to Regulate Bone morphogenetic protein 2 Gene Expression and Chicken Abdominal Fat Deposition

In this study, we employed a dual-luciferase reporter assay and electrophoretic mobility shift analysis (EMSA) in vitro to explore whether a 12-base pair (bp) insertion/deletion (InDel) variant (namely g.14798187_14798188insTCCCTGCCCCCT) within intron 2 of the chicken BMP2 gene, which was significantly associated with chicken abdominal fat weight and abdominal fat percentage, is a functional marker and its potential regulatory mechanism. The reporter analysis demonstrated that the luciferase activity of the deletion allele was extremely significantly higher than that of the insertion allele (p < 0.01). A bioinformatics analysis revealed that compared to the deletion allele, the insertion allele created a transcription factor binding site of nuclear factor-kappa B (NF-κB), which exhibited an inhibitory effect on fat deposition. A dual-luciferase reporter assay demonstrated that the inhibitory effect of NF-κB on the deletion allele was stronger than that on the insertion allele. EMSA indicated that the binding affinity of NF-κB for the insertion allele was stronger than that for the deletion allele. In conclusion, the 12-bp InDel chicken BMP2 gene variant is a functional variant affecting fat deposition in chickens, which may partially regulate BMP2 gene expression by affecting the binding of transcription factor NF-κB to the BMP2 gene.

AgRP Neuron-Specific Ablation Represses Appetite, Energy Intake, and Somatic Growth in Larval Zebrafish

Neuronal circuits regulating appetite are dominated by arcuate nucleus neurons, which include appetite-promoting and -suppressing neurons that release the orexigenic neuropeptide agouti-related protein (AgRP) and anorexigenic neuropeptide pro-opiomelanocortin, respectively, to compete for melanocortin receptors to modulate feeding behavior. In this study, we expressed novel agrp promoters, including different lengths of the 5' flanking regions of the agrp gene (4749 bp) in the zebrafish genome. We used the agrp promoter to derive the enhanced green fluorescent protein (EGFP)-nitroreductase (NTR) fusion protein, allowing expression of the green fluorescence signal in the AgRP neurons. Then, we treated the transgenic zebrafish AgRP4.7^NTR (Tg [agrp-EGFP-NTR]) with metronidazole to ablate the AgRP neurons in the larvae stage and observed a decline in their appetite and growth. The expression of most orexigenic and growth hormone/insulin-like growth factor axis genes decreased, whereas that of several anorexigenic genes increased. Our findings demonstrate that AgRP is a critical regulator of neuronal signaling for zebrafish appetite and energy intake control. Thus, AgRP4.7^NTR can be used as a drug-screening platform for therapeutic targets to treat human appetite disorders, including obesity. Furthermore, the unique agrp promoter we identified can be a powerful tool for research on AgRP neurons, especially AgRP neuron-mediated pathways in the hypothalamus, and appetite.

The involvement of peroxisome proliferator-activated receptor gamma (PPARγ) in anti-inflammatory activity of N-stearoylethanolamine

Background

N-stearoylethanolamine (NSE) is a bioactive lipid amine with a wide range of biological activities. Anti-inflammatory properties of NSE were previously confirmed on multiple animal models. However, the molecular mechanisms of anti-inflammatory action of NSE remain unclear. In the current study, we examined the involvement of nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) in the NF-kB –dependent pathway of anti-inflammatory action of NSE using different methodological approaches.

Methods

Molecular modeling calculated the possibility of NSE binding PPAR. Ex vivo experiment, using selective agonist of PPARα/γ - LY-171883 and antagonist of PPARγ - GW9662, examined the role of PPARα/γ in the NSE’s effect on nuclear NF-kB translocation in LPS-activated rat peritoneal macrophages. Finally, the NSE’s action on mRNA level of PPARγ-dependent genes was studied in the liver of insulin-resistant rats.

Results

The results of molecular docking showed that NSE could bind to PPARγ and compete for the binding site with antagonist GW9662 and agonist LY-171883. These data was supported by in vitro study where pre-treatment with NSE prevented further LPS-induced NF-kB translocation into the nuclei of rat peritoneal macrophages. NSE treatment before GW9662 and LPS addition normalized the level of NF-kB translocation and IL-1β content. This finding confirmed a competitive binding of NSE with GW9662 for the ligand-binding domain of PPARγ. Additional in vivo study showed that NSE administration changed the mRNA expression of several PPARγ target genes, including SLC27A1 encoding fatty acid transport protein-1 and IL1RN - interleukin-1 receptor antagonist in insulin resistant rats.

Conclusion

NSE suppressed nuclear translocation of NF-κB in LPS-stimulated peritoneal macrophages via PPARγ and changed hepatic mRNA expression of PPARγ target genes (SLC27A1, IL1RN) in insulin resistant rats.

On the Immunometabolic Role of NF-κB in Adipocytes

Two decades of research have established that Nuclear Factor-κB (NF-κB) signaling plays a critical role in reprogramming the fat cell transcriptome towards inflammation in response to overnutrition and metabolic stress. Several groups have suggested that inhibition of NF-κB signaling could have metabolic benefits for obesity-associated adipose tissue inflammation. However, two significant problems arise with this approach. The first is how to deliver general NF-κB inhibitors into adipocytes without allowing these compounds to disrupt normal functioning in cells of the immune system. The second issue is that general inhibition of canonical NF-κB signaling in adipocytes will likely lead to a massive increase in adipocyte apoptosis under conditions of metabolic stress, leading full circle into a secondary inflammation (However, this problem may not be true for non-canonical NF-κB signaling.). This review will focus on the research that has examined canonical and non-canonical NF-κB signaling in adipocytes, focusing on genetic studies that examine loss-of-function of NF-κB specifically in fat cells. Although the development of general inhibitors of canonical NF-κB signaling seems unlikely to succeed in alleviating adipose tissue inflammation in humans, the door remains open for more targeted therapeutics. In principle, these would include compounds that interrogate NF-κB DNA binding, protein-protein interactions, or post-translational modifications that partition NF-κB activity towards some genes and away from others in adipocytes. I also discuss the possibility for inhibitors of non-canonical NF-κB signaling to realize success in mitigating fat cell dysfunction in obesity. To plant the seeds for such approaches, much biochemical “digging” in adipocytes remains; this includes identifying—in an unbiased manner–NF-κB direct and indirect targets, genomic DNA binding sites for all five NF-κB subunits, NF-κB protein-protein interactions, and post-translational modifications of NF-κB in fat cells.

Asiatic acid protects articular cartilage through promoting chondrogenesis and inhibiting inflammation and hypertrophy in osteoarthritis

Natural small molecules have become attractive in osteoarthritis (OA) treatment. This study aims to investigate the effect of asiatic acid (AA) on OA development in vitro and in vivo. Chondrocytes were pretreated with AA at optimized concentrations and subsequently treated with interleukin-1 beta (IL-1β). Inflammatory mediator nitric oxide (NO) was measured by Griess method. The mRNA expression level of inflammatory markers nitric oxide synthase (iNOS) and cyclooxygenase 2 (Cox2), as well as chondrogenic or hypertrophic markers including SRY-box transcription factor 9 (Sox9), Aggrecan, Collagen 2a1 (Col II), and Matrix metalloproteinase-13 (Mmp13) were measured by using real-time PCR analysis. The nuclear factor-kappa B (NF-κB) signaling activity was determined by dual luciferase assay and Western blot analysis. Surgery-induced OA animal model was constructed, and AA was administrated to study its effect on OA pathogenesis. AA induced a dose-dependent inhibitory effect up to -67.4% on NO production. AA could repress iNOS and Cox2 protein expression levels (-77.2% and -73.4%, respectively) in IL-1β induced chondrocytes. AA increased the formation of cartilage extracellular matrix components including glycosaminoglycans (GAGs) and collagen type II. AA also mRNA expression of chondrogenesis marker including Aggrecan, Sox9, Col II and Fibronectin (402.87%, 151.04%, 314.15% and 187.76%, respectively) as well as hypertrophic marker Mmp13 (-67.8%). AA repressed the chondrocyte inflammation by directly inhibiting NF-κB signaling activity, which was revealed by the inhibition effect of AA on IκBα phosphorylation (-105.4%) and NF-κB/p65 translocation (-60.9%) induced by IL-1β. Furthermore, In vivo OA study indicated the protective effect of AA on OA progression by preventing articular cartilage from degeneration and destruction. AA treatment could significantly reduce OA score (16.125 vs 5.25) and repress mRNA expression level of Mmp13 and Col X (23.5, vs 2.375 and 18.125 vs 94.5). Taken together, our findings suggest that AA could effectively rescue IL-1β induced chondrocytes and protected cartilage in OA progression, which shed light on a potential novel therapeutic strategy of OA treatment.

Activation of the Peroxisome Proliferator-Activated Receptors (PPAR-α/γ) and the Fatty Acid Metabolizing Enzyme Protein CPT1A by Camel Milk Treatment Counteracts the High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease

Camel milk (CM) has a unique composition rich in antioxidants, trace elements, immunoglobulins, insulin, and insulin-like proteins. Treatment by CM demonstrated protective effects against nonalcoholic fatty liver disease (NAFLD) induced by a high-fat cholesterol-rich diet (HFD-C) in rats. CM dampened the steatosis, inflammation, and ballooning degeneration of the hepatocytes. It also counteracted hyperlipidemia, insulin resistance (IR), glucose intolerance, and oxidative stress. The commencement of NAFLD triggered the peroxisome proliferator-activated receptor-α (PPAR-α), carnitine palmitoyl-transferase-1 (CPT1A), and fatty acid-binding protein-1 (FABP1) and decreased the PPAR-γ expression in the tissues of the animals on HFD-C. This was associated with increased levels of the inflammatory cytokines IL-6 and TNF-α and leptin and declined levels of the anti-inflammatory adiponectin. Camel milk treatment to the NAFLD animals remarkably upregulated PPARs (α, γ) and the downstream enzyme CPT1A in the metabolically active tissues involved in cellular uptake and beta-oxidation of fatty acids. The enhanced lipid metabolism in the CM-treated animals was linked with decreased expression of FABP1 and suppression of IL-6, TNF-α, and leptin release with augmented adiponectin production. The protective effects of CM against the histological and biochemical features of NAFLD are at least in part related to the activation of the hepatic and extrahepatic PPARs (α, γ) with consequent activation of the downstream enzymes involved in fat metabolism. Camel milk treatment carries a promising therapeutic potential to NAFLD through stimulating PPARs actions on fat metabolism and glucose homeostasis. This can protect against hepatic steatosis, IR, and diabetes mellitus in high-risk obese patients.

Anti- and non-tumor necrosis factor-α-targeted therapies effects on insulin resistance in rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis

In addition to β-cell failure with inadequate insulin secretion, the crucial mechanism leading to establishment of diabetes mellitus (DM) is the resistance of target cells to insulin, i.e. insulin resistance (IR), indicating a requirement of beyond-normal insulin concentrations to maintain euglycemic status and an ineffective strength of transduction signaling from the receptor, downstream to the substrates of insulin action. IR is a common feature of most metabolic disorders, particularly type II DM as well as some cases of type I DM. A variety of human inflammatory disorders with increased levels of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β, have been reported to be associated with an increased risk of IR. Autoimmune-mediated arthritis conditions, including rheumatoid arthritis (RA), psoriatic arthritis (PsA) and ankylosing spondylitis (AS), with the involvement of proinflammatory cytokines as their central pathogenesis, have been demonstrated to be associated with IR, especially during the active disease state. There is an increasing trend towards using biologic agents and small molecule-targeted drugs to treat such disorders. In this review, we focus on the effects of anti-TNF-α- and non-TNF-α-targeted therapies on IR in patients with RA, PsA and AS. Anti-TNF-α therapy, IL-1 blockade, IL-6 antagonist, Janus kinase inhibitor and phospho-diesterase type 4 blocker can reduce IR and improve diabetic hyper-glycemia in autoimmune-mediated arthritis.

Short-chain fatty acids exert opposite effects on the expression and function of p-glycoprotein and breast cancer resistance protein in rat intestine

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are involved in intestinal barrier. Short-chain fatty acids (SCFAs) play important roles in maintaining intestinal barrier. In this study we explored how SCFAs affected the expression and function of intestinal P-gp and BCRP in rats. Rats received 150 mM acetate, propionate or butyrate in drinking water for 4 weeks. In SCFA-treated rats, the expression and function of intestinal P-gp were decreased, but those of intestinal BCRP were increased; intestinal p-p65 was also decreased, which was positively related to P-gp protein expression. Among the three SCFAs tested, butyrate exhibited the strongest induction or inhibitory effect, followed by propionate and acetate. Similar results were observed in mouse primary enterocytes and Caco-2 cells treated with acetate (5 mM), propionate (2 mM), or butyrate (1 mM). In Caco-2 cells, addition of butyrate, vorinostat, and valproate (two classic HDAC inhibitors), Bay117082 (selective inhibitor of NF-κB activation) or NF-κB p65 silencing significantly decreased the expression of P-gp and the level of phosphorylated p65 (p-p65). Furthermore, butyrate attenuated the expression of P-gp and p-p65 induced by TNF-α (NF-κB activator) and theophylline (HDAC activator). However, vorinostat, valproate, Bay117082, TNF-α or p65 silencing hardly affected BCRP protein expression. But GW9662 (selective PPARγ antagonist) or PPARγ silencing abolished BCRP induction by butyrate and troglitazone (PPARγ agonist). SCFAs-treated rats showed higher intestinal protein expression of PPARγ, which was positively related to BCRP protein expression. Butyrate increased plasma exposure of fexofenadine but decreased that of rosuvastatin following oral dose to rats. In conclusion, SCFAs exert opposite effects on the expression and function of intestinal P-gp and BCRP; butyrate downregulated P-gp expression and function possibly via inhibiting HDAC/NF-κB pathways; butyrate induced BCRP expression and function partly via PPARγ activation.

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

The Role of JNk Signaling Pathway in Obesity-Driven Insulin Resistance

Obesity is not only closely related to insulin resistance but is one of the main factors leading to the formation of Type 2 Diabetes (T2D) too. The c-Jun N-terminal kinase (JNK) family is a member of the mitogen-activated protein kinase (MAPK) superfamily. JNK is also one of the most investigated signal transducers in obesity and insulin resistance. JNK-centric JNK signaling pathway can be activated by growth factors, cytokines, stress responses, and other factors. Many researches have identified that the activated phosphorylation JNK negatively regulates insulin signaling pathway in insulin resistance which can be simultaneously regulated by multiple signaling pathways related to the JNK signaling pathway. In this review, we provide an overview of the composition of the JNK signaling pathway, its regulation of insulin signaling pathway, and the relationship between the JNK signaling pathway and other pathways in insulin resistance.

Nascent transcript analysis of glucocorticoid crosstalk with TNF defines primary and cooperative inflammatory repression

The glucocorticoid receptor (NR3C1, also known as GR) binds to specific DNA sequences and directly induces transcription of anti-inflammatory genes that contribute to cytokine repression, frequently in cooperation with NF-kB. Whether inflammatory repression also occurs through local interactions between GR and inflammatory gene regulatory elements has been controversial. Here, using global run-on sequencing (GRO-seq) in human airway epithelial cells, we show that glucocorticoid signaling represses transcription within 10 min. Many repressed regulatory regions reside within “hyper-ChIPable” genomic regions that are subject to dynamic, yet nonspecific, interactions with some antibodies. When this artifact was accounted for, we determined that transcriptional repression does not require local GR occupancy. Instead, widespread transcriptional induction through canonical GR binding sites is associated with reciprocal repression of distal TNF-regulated enhancers through a chromatin-dependent process, as evidenced by chromatin accessibility and motif displacement analysis. Simultaneously, transcriptional induction of key anti-inflammatory effectors is decoupled from primary repression through cooperation between GR and NF-kB at a subset of regulatory regions. Thus, glucocorticoids exert bimodal restraints on inflammation characterized by rapid primary transcriptional repression without local GR occupancy and secondary anti-inflammatory effects resulting from transcriptional cooperation between GR and NF-kB.

Feedback regulation of Arid5a and Ppar-γ2 maintains adipose tissue homeostasis

Immune cells infiltrate adipose tissues and provide a framework to regulate energy homeostasis. However, the precise underlying mechanisms and signaling by which the immune system regulates energy homeostasis in metabolic tissues remain poorly understood. Here, we show that the AT-rich interactive domain 5A (Arid5a), a cytokine-induced nucleic acid binding protein, is important for the maintenance of adipose tissue homeostasis. Long-term deficiency of Arid5a in mice results in adult-onset severe obesity. In contrast, transgenic mice overexpressing Arid5a are highly resistant to high-fat diet-induced obesity. Inhibition of Arid5a facilitates the in vitro differentiation of 3T3-L1 cells and fibroblasts to adipocytes, whereas its induction substantially inhibits their differentiation. Molecular studies reveal that Arid5a represses the transcription of peroxisome proliferator activated receptor gamma 2 (Ppar-γ2) due to which, in the absence of Arid5a, Ppar-γ2 is persistently expressed in fibroblasts. This phenomenon is accompanied by enhanced fatty acid uptake in Arid5a-deficient cells, which shifts metabolic homeostasis toward prolipid metabolism. Furthermore, we show that Arid5a and Ppar-γ2 are dynamically counterregulated by each other, hence maintaining adipogenic homeostasis. Thus, we show that Arid5a is an important negative regulator of energy metabolism and can be a potential target for metabolic disorders.

Inflammation and Immunity: From an Adipocyte's Perspective

Comprehension of adipocyte function has evolved beyond a long-held belief of their inert nature, as simple energy storing and releasing cells. Adipocytes, including white, brown, and beige, are capable mediators of global metabolic health, but their intersection with inflammation is a budding field of exploration. Evidence hints at a reciprocal relationship adipocytes share with immune cells. Adipocyte's capacity to behave in an "immune-like" manner and ability to sense inflammatory cues that subsequently alter core adipocyte function might play an important role in shaping immune responses. Clarifying this intricate relationship could uncover previously underappreciated contribution of adipocytes to inflammation-driven human health and disease. In this review, we highlight the potential of largely underappreciated adipocyte "immune-like" function and how it may contribute to inflammation, immunity, and pathology of various diseases.

Pioglitazone prevents sevoflurane‑induced neuroinflammation and cognitive decline in a rat model of chronic intermittent hypoxia by upregulating hippocampal PPAR‑γ

Post‑operative cognitive dysfunction is a common complication after anesthesia and surgery. Sevoflurane (SEV), a widely used inhalational anesthetic, can exaggerate neuroinflammation and cause cognitive dysfunction under chronic intermittent hypoxia (CIH) conditions by downregulating hippocampal peroxisome proliferator‑activated receptor‑γ (PPAR‑γ). In the present study, it was examined whether treatment with PPAR‑γ agonist pioglitazone (PIO) is beneficial in counteracting SEV‑induced neuroinflammation and cognitive decline in a rat model of CIH. Rats were exposed to CIH for 4 weeks. After 2 weeks of CIH, these animals underwent either 2.6% SEV or control (CON) exposure for 4 h. PIO (60 mg/kg) or vehicle (VEH) was administered orally twice daily for 2 weeks, starting one day prior to SEV or CON exposure. Compared with CIH‑CON+VEH rats, CIH‑SEV+VEH rats exhibited significant cognitive decline as indicated by increased latency to locate the hidden platform and shorter dwell‑time in the goal quadrant in the Morris Water Maze task. Molecular studies revealed that CIH‑SEV+VEH rats had increased proinflammatory cytokine expression and microglial activation in the hippocampus, which were associated with decreased PPAR‑γ activity. Notably, SEV‑induced cognitive decline and increases in proinflammatory cytokine expression and microglial activation were prevented by PIO, which increased hippocampal PPAR‑γ activity. PIO also increased hippocampal PPAR‑γ activity in CIH‑CON rats but did not alter proinflammatory cytokine expression and microglial activation as well as cognitive function. Additionally, expression of hippocampal PPAR‑α and PPAR‑β, two other PPAR isotypes, were comparable among the groups. These data suggest that PIO prevents SEV‑induced exaggeration of neuroinflammation and cognitive decline under CIH conditions by upregulating hippocampal PPAR‑γ. PIO may have the potential to prevent anesthetic SEV‑induced cognitive decline in surgical patients with obstructive sleep apnea.

Peroxisome Proliferator-Activated Receptor gamma negatively regulates liver regeneration after partial hepatectomy via the HGF/c-Met/ERK1/2 pathways

Peroxisome Proliferator-Activated Receptor gamma (PPARγ) is a nuclear receptor demonstrated to play an important role in various biological processes. The aim of this study was to determine the effect of PPARγ on liver regeneration upon partial hepatectomy (PH) in mice. Mice were subjected to two-thirds PH. Before surgery, mice were either treated with the PPARγ agonist rosiglitazone, the PPARγ antagonist GW9662 alone, or with the c-met inhibitor SGX523. Liver-to-body-weight ratio, lab values, and proliferation markers were assessed. Components of the PPARγ-specific signaling pathway were identified by western blot and qRT-PCR. Our results show that liver regeneration is being inhibited by rosiglitazone and accelerated by GW9662. Inhibition of c-Met by SGX523 treatment abrogates GW9662-induced liver regeneration and hepatocyte proliferation. Hepatocyte growth factor (HGF) protein levels were significantly downregulated after rosiglitazone treatment. Activation of HGF/c-Met pathways by phosphorylation of c-Met and ERK1/2 were inhibited in rosiglitazone-treated mice. In turn, blocking phosphorylation of c-Met significantly abrogated the augmented effect of GW9662 on liver regeneration. Our data support the concept that PPARγ abrogates liver growth and hepatocellular proliferation by inhibition of the HGF/c-Met/ERK1/2 pathways. These pathways may represent potential targets in response to liver disease and could impact on the development of molecular therapies.

An Anti-Inflammatory PPAR-γ Agonist from the Jellyfish-Derived Fungus Penicillium chrysogenum J08NF-4

An investigation of the jellyfish-derived fungus Penicillium chrysogenum J08NF-4 led to the isolation of two new meroterpene derivatives, chrysogenester (1) and 5-farnesyl-2-methyl-1-O-methylhydroquinone (2), and four known farnesyl meroterpenes. Docking analysis of 1 showed that it binds to PPAR-γ in the same manner as the natural PPAR-γ agonist amorfrutin B (7). Compound 1 activated PPAR-γ in murine Ac2F liver cells and increased nuclear PPAR-γ protein levels in murine RAW 264.7 macrophages. Because one of the main biological functions of PPAR-γ agonists is to suppress inflammatory response, an in vitro study was performed to explore the anti-inflammatory potency of 1 and the mechanism involved. In RAW 264.7 macrophages, 1 inhibited phosphorylation of the NF-κB p65 subunit and suppressed the expression of the pro-inflammatory mediators iNOS, NO, COX-2, TNF-α, IL-1β, and IL-6. We propose 1 suppresses inflammatory responses by activating PPAR-γ and subsequently downregulating the NF-κB signaling pathway, thus reducing the expressions of pro-inflammatory mediators.

IGFBP-3 Interacts with the Vitamin D Receptor in Insulin Signaling Associated with Obesity in Visceral Adipose Tissue

Adipose tissue has traditionally only been considered as an energy storage organ. Nevertheless, the importance of this tissue in systemic physiology and, especially, in systemic inflammation has been highlighted in recent years. Adipose tissue expresses proteins related to vitamin D (VD) metabolism, and it has been proposed that it can act as a VD storage tissue. The active form of VD, 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃), is able to modify adipocyte and adipose tissue physiology via the VD receptor (VDR), decreasing the expression of pro-inflammatory cytokines in adipose tissue. Moreover, VD deficiency and VDR has been reported to be associated with obesity and diabetes. However, the results of the different studies are not conclusive. Insulin growth binding proteins (IGFBPs) have been identified in adipose tissue, but their roles are poorly understood. Therefore, the objective of this study was to analyze the plasma levels of VD and the gene expression of VDR in the adipose tissue of subjects with morbid obesity (MO) and with different degrees of insulin resistance (IR), as well as the functionality of direct interaction between IGFBP-3 and VDR, which could explain its inhibitory role in adipogenesis. Our results show a novel role of the VD system in the regulation and activation of IGFBP-3 in visceral adipose tissue (VAT) of patients with MO, as a new and alternative mechanism proposed in the insulin signaling associated with obesity.

A Systems Pharmacology Approach to Determine Active Compounds and Action Mechanisms of Xipayi KuiJie'an enema for Treatment of Ulcerative colitis

Xipayi Kui Jie’an (KJA), a type of traditional Uygur medicine (TUM), has shown promising therapeutic effects in Ulcerative colitis (UC). Owing to the complexity of TUM, the pharmacological mechanism of KJA remains vague. Therefore, the identification of complex molecular mechanisms is a major challenge and a new method is urgently needed to address this problem. In this study, we established a feasible pharmacological model based on systems pharmacology to identify potential compounds and targets. We also applied compound-target and target-diseases network analysis to evaluate the action mechanisms. According to the predicted results, 12 active compounds were selected and these compounds were also identified by HPLC-ESI-MS/MS analysis. The main components were tannins, this result is consistent with the prediction. The active compounds interacted with 22 targets. Two targets including PTGS2 and PPARG were demonstrated to be the main targets associated with UC. Systematic analysis of the constructed networks revealed that these targets were mainly involved in NF-κB signaling pathway. Furthermore, KJA could also regulate the CD4 + CD25 + Foxp3 + Treg cells. In conclusion, this systems pharmacology-based approach not only explained that KJA could alleviate the UC by regulating its candidate targets, but also gave new insights into the potential novel therapeutic strategies for UC.

Thiazolidinedione (Pioglitazone) Blocks P. gingivalis- and F. nucleatum, but not E. coli, Lipopolysaccharide (LPS)-induced Interleukin-6 (IL-6) Production in Adipocytes

An elevated level of C-reactive protein (CRP) predicts the future development of coronary heart disease. Periodontitis appears to up-regulate CRP. CRP is produced by hepatocytes in response to interleukin-6 (IL-6). A major source of IL-6 in obese subjects is adipocytes. We hypothesized that lipopolysaccharide (LPS) from periodontal pathogens stimulated adipocytes to produce IL-6, and that the production was suppressed by the drugs targeted against insulin resistance, thiazolidinedione (pioglitazone), since this agent potentially showed an anti-inflammatory effect. Mouse 3T3-L1 adipocytes were stimulated with E. coli, P. gingivalis, and F. nucleatum LPS. The IL-6 concentration in culture supernatants was measured. All LPS stimulated adipocytes to produce IL-6. Although pioglitazone changed adipocyte appearance from large to small, and completely suppressed P. gingivalis and F. nucleatum LPS-induced IL-6 production, E. coli LPS-induced IL-6 production was not efficiently blocked. Thus, pioglitazone completely blocked periodontal-bacteria-derived LPS-induced IL-6 production in adipocytes, a major inducer of CRP.

NF-κB signaling pathway as target for antiplatelet activity

In different nucleated cells, NF-κB has long been considered a prototypical proinflammatory signaling pathway with the expression of proinflammatory genes. Although platelets lack a nucleus, a number of functional transcription factors are involved in activated platelets, such as NF-κB. In platelet activation NF-κB regulation events include IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation. Multiple pathways contribute to platelet activation and NF-κB is a common pathway in this activation. Therefore, in platelet activation the modulation of NF-κB pathway could be a potential new target in the treatment of inflammation-related vascular disease therapy (antiplatelet and antithrombotic activities).

The Ubiquitination of NF-κB Subunits in the Control of Transcription

Nuclear factor (NF)-κB has evolved as a latent, inducible family of transcription factors fundamental in the control of the inflammatory response. The transcription of hundreds of genes involved in inflammation and immune homeostasis require NF-κB, necessitating the need for its strict control. The inducible ubiquitination and proteasomal degradation of the cytoplasmic inhibitor of κB (IκB) proteins promotes the nuclear translocation and transcriptional activity of NF-κB. More recently, an additional role for ubiquitination in the regulation of NF-κB activity has been identified. In this case, the ubiquitination and degradation of the NF-κB subunits themselves plays a critical role in the termination of NF-κB activity and the associated transcriptional response. While there is still much to discover, a number of NF-κB ubiquitin ligases and deubiquitinases have now been identified which coordinate to regulate the NF-κB transcriptional response. This review will focus the regulation of NF-κB subunits by ubiquitination, the key regulatory components and their impact on NF-κB directed transcription.

Ligands for the Nuclear Peroxisome Proliferator-Activated Receptor Gamma

Nuclear receptors are ligand-activated transcription factors, which represent a primary class of drug targets. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) is a key player in various biological processes. PPARγ is widely known as the target protein of the thiazolidinediones for treating type 2 diabetes. Moreover, PPARγ ligands can induce anti-inflammatory and potentially additional beneficial effects. Recent mechanistic insights of PPARγ modulation give hope the next generation of efficient PPARγ-based drugs with fewer side effects can be developed. Furthermore, chemical approaches that make use of synergistic action of combinatorial ligands are promising alternatives for providing tailored medicine. Lessons learned from fine-tuning the action of PPARγ can provide avenues for efficient molecular intervention via many other nuclear receptors to combat common diseases.

Roles of NF-κB in Cancer and Inflammatory Diseases and Their Therapeutic Approaches

Nuclear factor-κB (NF-κB) is a transcription factor that plays a crucial role in various biological processes, including immune response, inflammation, cell growth and survival, and development. NF-κB is critical for human health, and aberrant NF-κB activation contributes to development of various autoimmune, inflammatory and malignant disorders including rheumatoid arthritis, atherosclerosis, inflammatory bowel diseases, multiple sclerosis and malignant tumors. Thus, inhibiting NF-κB signaling has potential therapeutic applications in cancer and inflammatory diseases.

Isoliquiritigenin Attenuates Adipose Tissue Inflammation in vitro and Adipose Tissue Fibrosis through Inhibition of Innate Immune Responses in Mice

Isoliquiritigenin (ILG) is a flavonoid derived from Glycyrrhiza uralensis and potently suppresses NLRP3 inflammasome activation resulting in the improvement of diet-induced adipose tissue inflammation. However, whether ILG affects other pathways besides the inflammasome in adipose tissue inflammation is unknown. We here show that ILG suppresses adipose tissue inflammation by affecting the paracrine loop containing saturated fatty acids and TNF-α by using a co-culture composed of adipocytes and macrophages. ILG suppressed inflammatory changes induced by the co-culture through inhibition of NF-κB activation. This effect was independent of either inhibition of inflammasome activation or activation of peroxisome proliferator-activated receptor-γ. Moreover, ILG suppressed TNF-α-induced activation of adipocytes, coincident with inhibition of IκBα phosphorylation. Additionally, TNF-α-mediated inhibition of Akt phosphorylation under insulin signaling was alleviated by ILG in adipocytes. ILG suppressed palmitic acid-induced activation of macrophages, with decreasing the level of phosphorylated Jnk expression. Intriguingly, ILG improved high fat diet-induced fibrosis in adipose tissue in vivo. Finally, ILG inhibited TLR4- or Mincle-stimulated expression of fibrosis-related genes in stromal vascular fraction from obese adipose tissue and macrophages in vitro. Thus, ILG can suppress adipose tissue inflammation by both inflammasome-dependent and -independent manners and attenuate adipose tissue fibrosis by targeting innate immune sensors.

Tumor-necrosis factor impairs CD4(+) T cell-mediated immunological control in chronic viral infection

Persistent viral infections are characterized by the simultaneous presence of chronic inflammation and T cell dysfunction. In prototypic models of chronicity--infection with human immunodeficiency virus (HIV) or lymphocytic choriomeningitis virus (LCMV)--we used transcriptome-based modeling to reveal that CD4(+) T cells were co-exposed not only to multiple inhibitory signals but also to tumor-necrosis factor (TNF). Blockade of TNF during chronic infection with LCMV abrogated the inhibitory gene-expression signature in CD4(+) T cells, including reduced expression of the inhibitory receptor PD-1, and reconstituted virus-specific immunity, which led to control of infection. Preventing signaling via the TNF receptor selectively in T cells sufficed to induce these effects. Targeted immunological interventions to disrupt the TNF-mediated link between chronic inflammation and T cell dysfunction might therefore lead to therapies to overcome persistent viral infection.

Integrative Genomic Analyses Yield Cell-Cycle Regulatory Programs with Prognostic Value

Liposarcoma is the second most common form of sarcoma, which has been categorized into four molecular subtypes, which are associated with differential prognosis of patients. However, the transcriptional regulatory programs associated with distinct histologic and molecular subtypes of liposarcoma have not been investigated. This study uses integrative analyses to systematically define the transcriptional regulatory programs associated with liposarcoma. Likewise, computational methods are used to identify regulatory programs associated with different liposarcoma subtypes, as well as programs that are predictive of prognosis. Further analysis of curated gene sets was used to identify prognostic gene signatures. The integration of data from a variety of sources, including gene expression profiles, transcription factor-binding data from ChIP-Seq experiments, curated gene sets, and clinical information of patients, indicated discrete regulatory programs (e.g., controlled by E2F1 and E2F4), with significantly different regulatory activity in one or multiple subtypes of liposarcoma with respect to normal adipose tissue. These programs were also shown to be prognostic, wherein liposarcoma patients with higher E2F4 or E2F1 activity associated with unfavorable prognosis. A total of 259 gene sets were significantly associated with patient survival in liposarcoma, among which > 50% are involved in cell cycle and proliferation.

IMPLICATIONS

These integrative analyses provide a general framework that can be applied to investigate the mechanism and predict prognosis of different cancer types.

New PPARγ partial agonist improves obesity-induced metabolic alterations and atherosclerosis in LDLr(-/-) mice

Peroxisome proliferator-activated receptor gamma (PPARγ) regulates multiple pathways involved in the pathogenesis of obesity and atherosclerosis. Here, we evaluated the therapeutic potential of GQ-177, a new thiazolidinedione, on diet-induced obesity and atherosclerosis. The intermolecular interaction between PPARγ and GQ-177 was examined by virtual docking and PPAR activation was determined by reporter gene assay identifying GQ-177 as a partial and selective PPARγ agonist. For the evaluation of biological activity of GQ-177, low-density lipoprotein receptor-deficient (LDLr(-/-)) C57/BL6 mice were fed either a high fat diabetogenic diet (diet-induced obesity), or a high fat atherogenic diet, and treated with vehicle, GQ-177 (20mg/kg/day), pioglitazone (20mg/kg/day, diet-induced obesity model) or rosiglitazone (15mg/kg/day, atherosclerosis model) for 28 days. In diet-induced obesity mice, GQ-177 improved insulin sensitivity and lipid profile, increased plasma adiponectin and GLUT4 mRNA in adipose tissue, without affecting body weight, food consumption, fat accumulation and bone density. Moreover, GQ-177 enhanced hepatic mRNA levels of proteins involved in lipid metabolism. In the atherosclerosis mice, GQ-177 inhibited atherosclerotic lesion progression, increased plasma HDL and mRNA levels of PPARγ and ATP-binding cassette A1 in atherosclerotic lesions. GQ-177 acts as a partial PPARγ agonist that improves obesity-associated insulin resistance and dyslipidemia with atheroprotective effects in LDLr(-/-) mice.

Metaflammatory responses during obesity: Pathomechanism and treatment

Obesity induced inflammation acts as a reflex produced due to altered metabolic homeostasis in accordance to the nutrient overload on the metabolic cells. It involves up-regulation of the genes encoding for cytokines, chemokines and other inflammatory mediators through activated transcription factors - nuclear factor-kB, activator protein-1, nuclear factor of activated T cells and signal transducer and activator of transcription 3. These execute macromolecular innate immune cell sensor - inflammasome to activate caspase-1 pathway resulting in proteolytic maturation. Secretion of pro-inflammatory cytokines including TNF-α, IL-6, CRP, IL-1β, etc. from the M1 macrophages of white adipose tissue is increased, whereas there occurs a steep decline in the production of anti-inflammatory cytokines like IL-10, IL-Ra, adiponectin. Not only the adipose tissue, but also the immune cells, liver, brain, muscles and pancreas suffers from the inflammatory insult during obese condition and are exaggeratedly affected. The inflammatory kinases like JNK and IKK apart from inhibiting insulin action and glucose uptake, down-regulate transcriptional process resulting in increased expression of pro-inflammatory cytokines. Macrophage-like Kupffer cells initiate the inflammatory process in the liver preceding the inflammatory signals produced by the white adipose tissue which may further lead to hepatic-necro-inflammation. The muscle-fibre is affected by the cytokines and therefore results in decreased glycogen synthesis. The triggered hypothalamic-pituitary-adrenal axis further affects the expression of inflammatory cytokines thus altering insulin homeostasis and initiating glucose intolerance. Anti-inflammatory treatment so as to curb the severity of inflammatory responses includes administration of synthetic drugs to target the actual inflammatory molecules and various therapeutic interventions.

Ubiquitin-mediated NFκB degradation pathway

The nuclear factor κB (NFκB) transcription factor plays critical roles in inflammation and immunity. The dysregulation of NFκB is associated with inflammatory and autoimmune diseases and cancer. NFκB activation is negatively regulated by the ubiquitin-dependent proteasomal degradation pathway. In the present review, we discuss recent advances in our understanding of how ubiquitin ligases regulate the NFκB degradation pathway.

Expression, regulation and functional assessment of the 80 amino acid Small Adipocyte Factor 1 (Smaf1) protein in adipocytes

The gene for Small Adipocyte Factor 1, Smaf1 (also known as adipogenin, ADIG), encodes a ∼600 base transcript that is highly upregulated during 3T3-L1 in vitro adipogenesis and markedly enriched in adipose tissues. Based on the lack of an obvious open reading frame in the Smaf1 transcript, it is not known if the Smaf1 gene is protein coding or non-coding RNA. Using a peptide from a putative open reading frame of Smaf1 as antigen, we generated antibodies for western analysis. Our studies prove that Smaf1 encodes an adipose-enriched protein which in western blot analysis migrates at ∼10 kDa. Rapid induction of Smaf1 protein occurs during in vitro adipogenesis and its expression in 3T3-L1 adipocytes is positively regulated by insulin and glucose. Moreover, siRNA studies reveal that expression of Smaf1 in adipocytes is wholly dependent on PPARγ. On the other hand, use of siRNA for Smaf1 to nearly abolish its protein expression in adipocytes revealed that Smaf1 does not have a major role in adipocyte triglyceride accumulation, lipolysis or insulin-stimulated pAkt induction. However, immunolocalization studies using HA-tagged Smaf1 reveal enrichment at adipocyte lipid droplets. Together our findings show that Smaf1 is a novel small protein endogenous to adipocytes and that Smaf1 expression is closely tied to PPARγ-mediated signals and the adipocyte phenotype.

Amorfrutins Are Natural PPARγ Agonists with Potent Anti-inflammatory Properties

Amorfrutins are isoprenoid-substituted benzoic acid derivatives, which were found in Amorpha fruticosa L. (bastard indigo) and in Glycyrrhiza foetida Desf. (licorice). Recently, amorfrutins were shown to be selective activators of the nuclear receptor PPARγ. Here, we investigated the effects and PPARγ-based mechanisms of reducing inflammation in colon cells by treatment with amorfrutins. In TNF-α-stimulated colon cells amorfrutin A (1) reduced significantly the expression and secretion of several inflammation mediators, in part due to interaction with PPARγ. These results support the hypothesis that amorfrutins may have the potential to treat inflammation disorders such as chronic inflammatory bowel diseases.

N-Stearoylethanolamine suppresses the pro-inflammatory cytokines production by inhibition of NF-κB translocation

N-Stearoylethanolamine (NSE) is a minor lipid that belongs to the N-Acylethanolamines family that mediates a wide range of biological processes. This study investigates the mechanisms of anti-inflammatory action of NSE on different model systems. Namely, we estimated the effect of NSE on inflammatory cytokines mRNA level (leukemia cells L1210), cytokines content (serum and LPS-stimulated macrophages) and nuclear translocation of NF-κB (peritoneal macrophages LPS-stimulated and isolated from rats with obesity-induced insulin resistance). The results indicated that NSE dose-dependently inhibits the IL-1 and IL-6 mRNA level in L1210 cells. Furthermore, the NSE treatment triggered a normalization of serum TNF-α level in insulin resistant rats and a reduction of medium IL-1 level in LPS-activated peritoneal macrophages. These NSE's effects were associated with the inhibition of nuclear NF-κB translocation in rat peritoneal macrophages.

MicroRNA-130a can inhibit hepatitis B virus replication via targeting PGC1α and PPARγ

In hepatitis B virus (HBV)-replicating hepatocytes, miR-130a expression was significantly reduced. In a reciprocal manner, miR-130a reduced HBV replication by targeting at two major metabolic regulators PGC1α and PPARγ, both of which can potently stimulate HBV replication. We proposed a positive feed-forward loop between HBV, miR-130a, PPARγ, and PGC1α. Accordingly, HBV can significantly enhance viral replication by reducing miR-130a and increasing PGC1α and PPARγ. NF-κB/p65 can strongly stimulate miR-130a promoter, while miR-130a can promote NF-κB/p65 protein level by reducing PPARγ and thus NF-κB/p65 protein degradation. We postulated another positive feed-forward loop between miR-130a and NF-κB/p65 via PPARγ. During liver inflammation, NF-κB signaling could contribute to viral clearance via its positive effect on miR-130a transcription. Conversely, in asymptomatic HBV carriers, persistent viral infection could reduce miR-130a and NF-κB expression, leading to dampened inflammation and immune tolerance. Finally, miR-130a could contribute to metabolic homeostasis by dual targeting PGC1α and PPARγ simultaneously.

Effects of intravenous glucose and lipids on innate immune cell activation in healthy, obese, and type 2 diabetic subjects

Atherosclerosis/cardiovascular disease are major causes of morbidity/mortality in obesity and type 2 diabetes (T2D), and have been associated with activation of innate immune cells, their diapedesis to the arterial intima and formation of the atherosclerotic plaque. While in obesity/T2D immune cell activation likely depends on dysregulated metabolism, the interaction between individual metabolic factors typical of these conditions (hyperglycemia, hyperlipidemia), innate immune cell activation, and the progression of atherosclerosis remains unclear. We, therefore, measured by flow cytometry cell surface expression of CD11b, CD14, CD16, CD62L, and CD66b, known markers of granulocyte (Gc) and monocyte (Mc) activation, in five healthy, five obese, and five T2D subjects, during 4-h i.v. infusions of 20% dextrose (raising blood sugar levels to ~220 mg/dL), 20% Intralipid (raising trygliceride levels to ~6 mmol/L), or a combination of the two. We hypothesized that both glucose and lipids would increase Gc/Mc surface marker expression, and simultaneous infusion would have an additive or synergistic effect. Surprisingly, though, infusion of glucose alone had little effect, while lipids, alone or combined with glucose, significantly increased expression of several markers (such as CD11b in Gc and Mc, and CD66 b in GC) within 60-90 min. Less pronounced increases in systemic inflammatory cytokines also occurred in obese and T2D subject, with no acute changes in gene expression of the the proinflammatory genes NFκB and CCR2. Our results suggest that lipids may be stronger acute contributors to innate cell activation than acute hyperglycemia per se, possibly helping shape more effective preventive dietary guidelines in T2D.

PPARγ E3 ubiquitin ligase regulates MUC1-C oncoprotein stability

MUC1-C oncoprotein is associated with colon, breast, ovarian, lung and pancreatic cancers. MUC1-C interacts with intracellular proteins to elicit signaling cascades that induce cell proliferation and tumor growth. Here we report that peroxisome proliferator-activated receptor gamma (PPARγ), an E3 ubiquitin ligase, is an inhibitor of MUC1-C-mediated cell proliferation. PPARγ does so by binding to and inducing MUC1-C proteasome-dependent degradation that was independent of PPARγ transcriptional activity. Lys134 residue was found to be critically important for PPARγ-mediated MUC1-C degradation, as it terminated MUC1-C-mediated cell proliferation. These findings demonstrate PPARγ induces MUC1-C ubiquitination and degradation that is critical to terminate MUC1-C signaling pathway-elicited cancer.

Modulation of Diabetes and Dyslipidemia in Diabetic Insulin-Resistant Rats by Mangiferin: Role of Adiponectin and TNF-α

Mangiferin, present in Mangifera indica bark, was reported to produce hypoglycemic and antidiabetic activity in an animal model of genetic type 2 diabetes and in streptozotocin diabetic rats. Its effect on diabetic insulin-resistant animals has not been investigated. The current work aimed to explore the effect of mangiferin on diabetic insulin-resistant rat model. Diabetes was induced by high-fat/high fructose diet for eight weeks followed by a subdiabetogenic dose of streptozotocin (HFD-Fr-STZ). Rats were treated with mangiferin (20 mg/kg i.p.) for 28 days starting one week after STZ and its effects were compared to the standard insulin sensitizer, rosiglitazone. HFD-Fr-STZ, induced obesity, hyperglycemia and insulin resistance accompanied by depletion in liver glycogen and dyslipidemia. Moreover, there was an elevation in serum TNF-α and a reduction in adiponectin. Mangiferin ameliorated the consequences of HFD-Fr-STZ and its actions were comparable to the effects of the standard insulin sensitizer, rosiglitazone. The results obtained in this study provide evidence that mangiferin is a possible beneficial natural compound for type 2 diabetes and metabolic disorders associated with the metabolic syndrome. This effect is mediated through improving insulin sensitivity, modulating lipid profile and reverting adipokine levels to normal.

Glutamine synthetase desensitizes differentiated adipocytes to proinflammatory stimuli by raising intracellular glutamine levels

The role of glutamine synthetase (GS) during adipocyte differentiation is unclear. Here, we assess the impact of GS on the adipocytic response to a proinflammatory challenge at different differentiation stages. GS expression at the late stages of differentiation desensitized mature adipocytes to bacterial lipopolysaccharide (LPS) by increasing intracellular glutamine levels. Furthermore, LPS-activated mature adipocytes were unable to produce inflammatory mediators; LPS sensitivity was rescued following GS inhibition and the associated drop in intracellular glutamine levels. The ability of adipocytes to differentially respond to LPS during differentiation negatively correlates to GS expression and intracellular glutamine levels. Hence, modulation of intracellular glutamine levels by GS expression represents an endogenous mechanism through which mature adipocytes control the inflammatory response.

Network analysis identifies SOD2 mRNA as a potential biomarker for Parkinson's disease

Increasing evidence indicates that Parkinson's disease (PD) and type 2 diabetes (T2DM) share dysregulated molecular networks. We identified 84 genes shared between PD and T2DM from curated disease-gene databases. Nitric oxide biosynthesis, lipid and carbohydrate metabolism, insulin secretion and inflammation were identified as common dysregulated pathways. A network prioritization approach was implemented to rank genes according to their distance to seed genes and their involvement in common biological pathways. Quantitative polymerase chain reaction assays revealed that a highly ranked gene, superoxide dismutase 2 (SOD2), is upregulated in PD patients compared to healthy controls in 192 whole blood samples from two independent clinical trials, the Harvard Biomarker Study (HBS) and the Diagnostic and Prognostic Biomarkers in Parkinson's disease (PROBE). The results from this study reinforce the idea that shared molecular networks between PD and T2DM provides an additional source of biologically meaningful biomarkers. Evaluation of this biomarker in de novo PD patients and in a larger prospective longitudinal study is warranted.

miR-27 inhibits adipocyte differentiation via suppressing CREB expression

miR-27 plays a negative role in the regulation of adipogenesis. However, the molecular mechanism still remains to be clarified. In the present study, we found that miR-27 inhibits adipogenesis partially by repressing the early adipogenic transcription factor cAMP response element-binding protein by directly targeting its 3' untranslated region. In addition, we demonstrated that tumor necrosis factor-α (TNF-α) treatment up-regulates miR-27 through the NF-κB pathway. Furthermore, anti-miR-27 reduces the TNF-α-induced inhibition of adipogenesis. Simultaneously, the levels of miR-27 expression were decreased in mature adipocytes of obese mice when compared with lean mice. Our data revealed a novel mechanism of miR-27 in the regulation of adipogenesis.

MicroRNA-494, upregulated by tumor necrosis factor-α, desensitizes insulin effect in C2C12 muscle cells

Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue of vertebrates. Although several miRNAs are thought to be involved in the development of insulin resistance, the role of miRNAs in the association between inflammation and insulin resistance in muscle tissue is poorly understood. Herein, we investigated the aberrant expression of miRNAs by conducting miRNA microarray analysis of TNF-α-treated mouse C₂C₁₂ myotubes. We identified two miRNAs that were upregulated and six that were downregulated by a >1.5-fold change compared to normal cells. Among the findings, qRT-PCR analysis confirmed that miR-494 is consistently upregulated by TNF-α-induced inflammation. Overexpression of miR-494 in CHO_IR/IRS1 and C₂C₁₂ myoblasts suppressed insulin action by down-regulating phosphorylations of GSK-3α/β, AS160 and p70S6K, downstream of Akt. Moreover, overexpression of miR-494 did not regulate TNF-α-mediated inflammation . Among genes bearing the seed site for miR-494, RT-PCR analysis showed that the expression of Stxbp5, an inhibitor of glucose transport, was downregulated following miR-494 inhibition. In contrast, the expression of PTEN decreased in the cells analyzed, thus showing that both positive and negative regulators of insulin action may be simultaneously controlled by miR-494. To investigate the overall effect of miR-494 on insulin signaling, we performed a PCR array analysis containing 84 genes related to the insulin signaling pathway, and we observed that 25% of genes were downregulated (P<0.05) and 11% were upregulated (P<0.05). These results confirm that miR-494 might contribute to insulin sensitivity by positive and negative regulation of the expression of diverse genes. Of note, PCR array data showed downregulation of Slc2A4, a coding gene for Glut4. Altogether, the present study concludes that the upregulation of miR-494 expression by TNF-α-mediated inflammation exacerbates insulin resistance. Therefore, we suggest that miR-494 could prove an important target for the diagnosis and therapy of inflammation-mediated insulin resistance in muscle.

The abundance of fecal Faecalibacterium prausnitzii in relation to obesity and gender in Chinese adults

The influence of gender and obesity on the abundance of human colonic Feacalibacterium prausnitzii is currently unclear. We collected fecal samples from 54 obese and 54 sex- and age-matched normal-weight Chinese adults and quantified the fecal F. prausnitzii as percentage of 16S rRNA gene copies of F. prausnitzii accounting to that of total gut bacteria with quantitative PCR. The fecal F. prausnitzii amount was not significantly different between obese and lean subjects. Men possessed significantly lower level of fecal F. prausnitzii than women, and the significant and positive correlation of fecal F. prausnitzii quantity with fasting glucose level was observed in men, not in women. Our results suggest that the gender effect, in addition to other factors including the geographic location, ethnicity, diet and gut transit times of study subjects, has to be considered when studying the relationship between gut F. prausnitzii and diseases.

Hypoxia downregulates PPARγ via an ERK1/2-NF-κB-Nox4-dependent mechanism in human pulmonary artery smooth muscle cells

The ligand-activated transcription factor peroxisome proliferator-activated receptor γ (PPARγ) regulates metabolism, cell proliferation, and inflammation. Pulmonary hypertension (PH) is associated with reduced PPARγ expression, and hypoxia exposure regimens that cause PH reduce PPARγ expression. This study examines mechanisms of hypoxia-induced PPARγ downregulation in vitro and in vivo. Hypoxia reduced PPARγ mRNA and protein levels, PPARγ activity, and the expression of PPARγ-regulated genes in human pulmonary artery smooth muscle cells (HPASMCs) exposed to 1% oxygen for 72 h. Similarly, exposure of mice to hypoxia (10% O₂) for 3 weeks reduced PPARγ mRNA and protein in mouse lung. Inhibiting ERK1/2 with PD98059 or treatment with siRNA directed against either NF-κB p65 or Nox4 attenuated hypoxic reductions in PPARγ expression and activity. Furthermore, degradation of H₂O₂ using PEG-catalase prevented hypoxia-induced ERK1/2 phosphorylation and Nox4 expression, suggesting sustained ERK1/2-mediated signaling and Nox4 expression in this response. Mammalian two-hybrid assays demonstrated that PPARγ and p65 bind directly to each other in a mutually repressive fashion. We conclude from these results that hypoxic regimens that promote PH pathogenesis and HPASMC proliferation reduce PPARγ expression and activity through ERK1/2-, p65-, and Nox4-dependent pathways. These findings provide novel insights into mechanisms by which pathophysiological stimuli such as hypoxia cause loss of PPARγ activity and pulmonary vascular cell proliferation, pulmonary vascular remodeling, and PH. These results also indicate that restoration of PPARγ activity with pharmacological ligands may provide a novel therapeutic approach in selected forms of PH.

Antibiotic and anti-inflammatory therapies for cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by chronic bacterial infection and an unremitting inflammatory response, which are responsible for most of CF morbidity and mortality. The median expected survival has increased from <6 mo in 1940 to >38 yr now. This dramatic improvement, although not great enough, is due to the development of therapies directed at secondary disease pathologies, especially antibiotics. The importance of developing treatments directed against the vigorous inflammatory response was realized in the 1990s. New therapies directed toward the basic defect are now visible on the horizon. However, the impact of these drugs on downstream pathological consequences is unknown. It is likely that antibiotics and anti-inflammatory drugs will remain an important part of the maintenance regimen for CF in the foreseeable future. Current and future antibiotic and anti-inflammatory therapies for CF are reviewed.

MiRNA-181a regulates adipogenesis by targeting tumor necrosis factor-α (TNF-α) in the porcine model

Adipogenesis is tightly regulated by altering gene expression, and TNF-α is a multifunctional cytokine that plays an important role in regulating lipogenesis. MicroRNAs are strong post-transcriptional regulators of cell differentiation. In our previous work, we found high expression of miR-181a in a fat-rich pig breed. Using bioinformatic analysis, miR-181a was identified as a potential regulator of TNF-α. Here, we validated TNF-α as the target of miR-181a by a dual luciferase assay. In response to adipogenesis, a mimic or inhibitor was used to overexpress or reduce miR-181a expression in porcine pre-adipocytes, which were then induced into mature adipocytes. Overexpression of miR-181a accelerated accumulation of lipid droplets, increased the amount of triglycerides, and repressed TNF-α protein expression, while the inhibitor had the opposite effect. At the same time, TNF-alpha rescued the increased lipogenesis by miR181a mimics. Additionally, miR-181a suppression decreased the expression of fatty synthesis associated genes PDE3B (phosphodiesterase 3B), LPL (lipoprotein lipase), PPARγ (proliferator-activated receptor-γ), GLUT1(glucose transporter), GLUT4, adiponectin and FASN (fatty acid synthase), as well as key lipolytic genes HSL (hormone-sensitive lipase) and ATGL (adipose triglyceride lipase) as revealed by quantitative real-time PCR. Our study provides the first evidence of the role of miR-181a in adipocyte differentiation by regulation of TNF-α, which may became a new therapeutic target for anti-obesity drugs.