MicroRNA-511-3p Mediated Modulation of the Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Controls LPS-Induced Inflammatory Responses in Human Monocyte Derived DCs

The peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor expressed in dendritic cells (DCs), where it exerts anti-inflammatory responses against TLR4-induced inflammation. Recently, microRNA-511 (miR-511) has also emerged as a key player in controlling TLR4-mediated signalling and in regulating the function of DCs. Interestingly, PPARγ has been previously highlighted as a putative target of miR-511 activity; however, the link between miR-511 and PPARγ and its influence on human DC function within the context of LPS-induced inflammatory responses is unknown. Using a selection of miR-511-3p-specific inhibitors and mimics, we demonstrate for the first time that knockdown or overexpression of miR-511-3p inversely correlates with PPARγ mRNA levels and affects its transcriptional activity following treatment with rosiglitazone (RSG; PPARγ agonist), in the presence or absence of LPS. Additionally, we show that PPARγ-mediated suppression of DC activation and pro-inflammatory cytokine production in miR-511-3p knockdown DCs is abrogated following overexpression of miR-511-3p. Lastly, PPARγ activation suppressed LPS-mediated induction of indoleamine 2,3-dioxygenase (IDO) activity in DCs, most likely due to changes in miR-511-3p expression. Our data thus suggests that PPARγ-induced modulation of DC phenotype and function is influenced by miR-511-3p expression, which may serve as a potential therapeutic target against inflammatory diseases.

Effect of nutmeg extract on the white adipose tissue (WAT) browning process of aging rats

The white adipose tissue (WAT) browning process has become one of the promising methods for managing obesity. During this process, WAT is transformed into brown-like adipose tissue, which is also known as beige adipose tissue. The browning process can be activated by several inducers. One of the best candidates is peroxisome proliferator-activated receptor γ (PPARγ) agonist. Nutmeg (Myristica fragrans Houtt) is a natural PPARα/γ partial agonist that is known to contribute to the browning effect. This study aimed to explore the potential effect of nutmeg seed extract (NuSE) on body weight reduction and uncoupling protein (UCP)1, UCP2, UCP3, and peroxisome proliferator-activated receptor gamma coactivator-1 PGC-1α levels in aging rats. Eight male Wistar rats (80 weeks old) were divided into control and treatment groups. Both groups were fed a standard diet, and the treatment group was given 8.1 mg/kg body weight/day of NuSE via oral gavage for 12 weeks. After 12 weeks, the levels of UCP1, UCP2, UCP3, and PGC-1α from both inguinal WAT (iWAT) and interscapular brown adipose tissue (BAT) were examined. We observed that the administration of NuSE has no significant effect to the decreasement of rats body weights (p = 0.464), levels of UCP1 (p = 0.686), UCP2 (p = 0.360), UCP3 (p = 0.076), and PGC-1α (p = 0.200).

Molecular Dynamics Free Energy Simulation study to Investigate Binding Pattern of Isoliquiritigenin as PPAR𝛾 Agonist

Phytochemicals are rich source of bioactive constituents and can be used as another alternative to currently used drugs for diseases like Diabetes mellitus. The potential of Isoliquiritigenin (a constituent of Pterocarpus marsupium) as PPAR𝛾 agonist was evaluated by in silico technique. Autodock results showed that Tyr327, and Tyr473 of the PPARγ forms H-bonds with Isoliquiritigenin (binding energy of -7.46 kcal/mol) and Troglitazone (known drug) showed H bond with Tyr327, Ser289, with binding energy of -11.01 kcal/mol. Isoliquiritigenin, binding energy in Extra precision (XP) was -6.74 kcal/mol while Troglitazone docking, gave binding energy in XP mode as -9.59 kcal/mol. The best Induced fit docking (IFD) score of the optimised PPARγ- Isoliquiritigenin complexes was -9.39 Kcal/mol. The important residues in IFD forming H bond were Cys 285, Arg 288, Tyr 327 and Leu 340. The post docking MM/GBSA free energy for PPARγ with Isoliquiritigenin and Troglitazone was -49.29 and -71.48 Kcal/mol respectively. Binding interaction in MD simulation and Principal Component Analysis studies revealed stable binding throughout 100 ns simulation. Post Simulation MM/PBSA free energy was calculated. The results indicated that compound possessed a negative binding free energy with -114.37KJ/mol. It was observed that van der Waals, electrostatic interactions and non-polar solvation energy negatively contributed to the total interaction energy while only polar solvation energy positively contributed to total free binding energy. The Isoliquiritigenin fulfils the criteria of drug-likeness property. Thus, study presents a systematic analysis on molecular mechanism of action of Isoliquiritigenin as PPARγ agonist in controlling Diabetes mellitus.

PPARγ Regulates Triclosan Induced Placental Dysfunction

Exposure to the antibacterial agent triclosan (TCS) is associated with abnormal placenta growth and fetal development during pregnancy. Peroxisome proliferator-activated receptor γ (PPARγ) is crucial in placenta development. However, the mechanism of PPARγ in placenta injury induced by TCS remains unknown. Herein, we demonstrated that PPARγ worked as a protector against TCS-induced toxicity. TCS inhibited cell viability, migration, and angiogenesis dose-dependently in HTR-8/SVneo and JEG-3 cells. Furthermore, TCS downregulated expression of PPARγ and its downstream viability, migration, angiogenesis-related genes HMOX1, ANGPTL4, VEGFA, MMP-2, MMP-9, and upregulated inflammatory genes p65, IL-6, IL-1β, and TNF-α in vitro and in vivo. Further investigation showed that overexpression or activation (rosiglitazone) alleviated cell viability, migration, angiogenesis inhibition, and inflammatory response caused by TCS, while knockdown or inhibition (GW9662) of PPARγ had the opposite effect. Moreover, TCS caused placenta dysfunction characterized by the significant decrease in weight and size of the placenta and fetus, while PPARγ agonist rosiglitazone alleviated this damage in mice. Taken together, our results illustrated that TCS-induced placenta dysfunction, which was mediated by the PPARγ pathway. Our findings reveal that activation of PPARγ might be a promising strategy against the adverse effects of TCS exposure on the placenta and fetus.

Combination of Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Agonist and PPAR Gamma Co-Activator 1α (PGC-1α) Activator Ameliorates Cognitive Deficits, Oxidative Stress, and Inflammation in Rodent Model of Parkinson's Disease

Background: PPAR gamma co-activator 1α (PGC-1α) is known as the master regulator of mitochondrial biogenesis. It is also a co-activator of peroxisome proliferator-activated receptor-gamma (PPARγ) and plays a role in preventing mitochondrial dysfunction in several neurodegenerative disorders, including Parkinson’s disease (PD). Depletion in the levels of these proteins has been linked to oxidative stress, inflammation, and DNA damage, all of which are known to contribute to the pathogenesis of PD. Objective: In the present study, combination therapy of PPARγ agonist (GW1929) and PGC-1α activator (alpha-lipoic acid) was employed to ameliorate cognitive deficits, oxidative stress, and inflammation associated with the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. Results: Our study showed that MPTP-induced PD rats exhibited an increase in oxidative stress and inflammation, leading to cognitive deficits. Furthermore, MPTP-induced PD rats also exhibited reduced mitochondrial biogenesis in comparison to control and sham animals. Intraperitoneal administration of GW 1929 and alpha-lipoic acid in doses lower than those earlier reported individually in literature led to an improvement in the cognitive deficits in comparison to MPTP-induced PD rats. These improvements were accompanied by a reduction in the levels of oxidative stress and inflammation. In addition, an increase in mitochondrial biogenesis was also observed after the combination of these pharmacological agents. Conclusion: Our results provide a rationale for the development of agents targeting PPARγ and PGC-1α as potent therapeutics for the treatment of neurological diseases like PD.

Regulation of Epigenetic Modifications in the Placenta During Preeclampsia: PPARγ Influences H3K4me3 and H3K9ac in Extravillous Trophoblast Cells

The aim of this study was to analyze the expression of peroxisome proliferator-activated receptor γ (PPARγ) and retinoid X receptor α (RxRα), a binding heterodimer playing a pivotal role in the successful trophoblast invasion, in the placental tissue of preeclamptic patients. Furthermore, we aimed to characterize a possible interaction between PPARγ and H3K4me3 (trimethylated lysine 4 of the histone H3), respectively H3K9ac (acetylated lysine 9 of the histone H3), to illuminate the role of histone modifications in a defective trophoblast invasion in preeclampsia (PE). Therefore, the expression of PPARγ and RxRα was analyzed in 26 PE and 25 control placentas by immunohistochemical peroxidase staining, as well as the co-expression with H3K4me3 and H3K9ac by double immunofluorescence staining. Further, the effect of a specific PPARγ-agonist (Ciglitazone) and PPARγ-antagonist (T0070907) on the histone modifications H3K9ac and H3K4me3 was analyzed in vitro. In PE placentas, we found a reduced expression of PPARγ and RxRα and a reduced co-expression with H3K4me3 and H3K9ac in the extravillous trophoblast (EVT). Furthermore, with the PPARγ-antagonist treated human villous trophoblast (HVT) cells and primary isolated EVT cells showed higher levels of the histone modification proteins whereas treatment with the PPARγ-agonist reduced respective histone modifications. Our results show that the stimulation of PPARγ-activity leads to a reduction of H3K4me3 and H3K9ac in trophoblast cells, but paradoxically decreases the nuclear PPARγ expression. As the importance of PPARγ, being involved in a successful trophoblast invasion has already been investigated, our results reveal a pathophysiologic connection between PPARγ and the epigenetic modulation via H3K4me3 and H3K9ac in PE.

Cytochrome P450 2E1 Predicts Liver Retrieval from Donation After Circulatory Death Using Air-Ventilated Normothermic Machine Perfusion

The optimal oxygen concentration is unclear for normothermic machine perfusion (NMP) of livers from donation after circulatory death donors (DCD). Our purposes were to investigate the effect of air-ventilated NMP on liver retrieval from DCD rats, and to analyze the underlying mechanism. Normothermic liver perfusion was performed using the NMP system with either air ventilation or oxygen ventilation for 2h in the rat liver following warm ischemia and cold ischemia preservation. Proteomics and metabolomics were used to reveal the significant molecular networks. The bioinformation analysis was validated by administering peroxisome proliferator activator receptor-γ (PPARγ) antagonist and agonist via ex vivo perfusion circuit in the air-ventilated NMP. Results showed that air-ventilated NMP conferred a better functional retrieval and a less inflammatory response in the rat DCD liver; integrated proteomics and metabolomics analysis indicated that intrahepatic docosapentaenoic acid (DPA) downregulation and upregulation of cytochrome P450 2E1 (CYP2E1) expression and activity were associated with DCD liver retrieval with air-ventilated NMP; PPARγ antagonist worsened liver function under air-oxygenated NMP whereas PPARγ agonist played the opposite role. In conclusion, air-ventilated NMP confers a better liver retrieval from DCD rats through the DAP-PPARγ-CYP2E1 axis; CYP2E1 activity provides a biomarker of liver retrieval from DCD.

Coordinated regulation of gene expression and microRNA changes in adipose tissue and circulating extracellular vesicles in response to pioglitazone treatment in humans with type 2 diabetes

Pioglitazone, a PPARγ agonist, is used to treat type 2 diabetes (T2D). PPARγ is highly expressed in adipose tissue (AT), however the effects of pioglitazone to improve insulin sensitivity are also evident in other tissues. We hypothesized that pioglitazone modifies the cargo of circulating AT-derived extracellular vesicles (EVs) to alter interorgan crosstalk. We tested this in a 3-month trial in which 24 subjects with T2D who were well-controlled with diet/exercise or metformin were randomized to treatment with either pioglitazone 45 mg/day or placebo (NCT00656864). Levels of 42 adipocyte-derived EV-miRNAs were measured in plasma EVs. Levels of 5 miRNAs (i.e., miR-7-5p, miR-20a-5p, miR-92a-3p, miR-195-5p, and miR-374b-5p) were significantly downregulated in EVs in response to pioglitazone treatment relative to placebo. However, the opposite occurred for miR-195-5p in subcutaneous AT from the same participants. Changes in miRNA expression in EVs and AT correlated with changes in suppression of lipolysis and improved insulin sensitivity, among others. DICER was downregulated and exosomal miRNA sorting-related genes YBX1 and hnRNPA2B1 displayed a trend toward downregulation in AT. Furthermore, analysis of EV-miRNA targeted genes identified a network of overtargeted transcripts that changed in a coordinated manner in AT. Collectively, our results suggest that some beneficial pharmacologic effects of PIO are mediated by adipose-specific miRNA regulation and exosomal/EV trafficking.

Histone H4 lysine 16 acetylation controls central carbon metabolism and diet-induced obesity in mice

Noncommunicable diseases (NCDs) account for over 70% of deaths world-wide. Previous work has linked NCDs such as type 2 diabetes (T2D) to disruption of chromatin regulators. However, the exact molecular origins of these chronic conditions remain elusive. Here, we identify the H4 lysine 16 acetyltransferase MOF as a critical regulator of central carbon metabolism. High-throughput metabolomics unveil a systemic amino acid and carbohydrate imbalance in Mof deficient mice, manifesting in T2D predisposition. Oral glucose tolerance testing (OGTT) reveals defects in glucose assimilation and insulin secretion in these animals. Furthermore, Mof deficient mice are resistant to diet-induced fat gain due to defects in glucose uptake in adipose tissue. MOF-mediated H4K16ac deposition controls expression of the master regulator of glucose metabolism, Pparg and the entire downstream transcriptional network. Glucose uptake and lipid storage can be reconstituted in MOF-depleted adipocytes in vitro by ectopic Glut4 expression, PPARγ agonist thiazolidinedione (TZD) treatment or SIRT1 inhibition. Hence, chronic imbalance in H4K16ac promotes a destabilisation of metabolism triggering the development of a metabolic disorder, and its maintenance provides an unprecedented regulatory epigenetic mechanism controlling diet-induced obesity.