PPARγ Signaling Pathway Research Articles

Insulin promotes macrophage phenotype transition through PI3K/Akt and PPAR-γ signaling during diabetic wound healing.

Overactivation and persistent chronic inflammation are the major pathogenic characteristics of diabetic-impaired healing, and diabetic wound healing can be promoted by stimulating the transition of macrophage phenotype from pro-inflammatory (M1) to anti-inflammatory (M2). Our previous studies found that the application of insulin induced an advanced initiation and resolution of inflammatory response. To further explore the mechanism, we have investigated the effect of insulin on macrophage phenotype switch utilizing a diabetic rat model and a human monocytic THP-1 cell. We have utilized the high glucose (HG) and HG plus insulin to stimulate the M1 macrophages derived from lipopolysaccharide-treated THP-1 cells. We studied the secretion of inflammatory mediator and related signaling pathways by using western blot test, immunofluorescence, and Rac1 pull-down assay. We have found that the production of pro-inflammatory mediators, which thereafter induced macrophage polarization toward M1 phenotype, has been elevated due to consistent HG exposure. HG plus insulin stimulation, on the other hand, promoted anti-inflammatory effects. Experiments performed on diabetic burn wounds indicated that the insulin modulated macrophages transition from M1 to M2 phenotype. We found that PI3K/Akt/Rac-1 and PPAR-γ signaling pathways are involved in the anti-inflammatory effect of insulin. Insulin inhibited HG-induced activation of p38, NF-κB, and STAT1 transcriptional activity by activating Akt-Rac-1 signaling. Moreover, insulin performs anti-inflammatory effects through upregulation of PPAR-γ expression and induced P38-mediated dephosphorylation of PPAR-γ (Ser112). In conclusion, insulin downregulates inflammatory response, regulates M1 macrophage transition in response to HG, and thus improves chronic wound healing.

Effect of telmisartan on peroxisome proliferator-activated receptor γ signaling pathway in 3T3-L1 adipocytes

Objective: To investigate the mechanisms of telmisartan on delaying the course of type 2 diabetes. Methods: 3T3-L1 preadipocytes were induced to 80% mature adipocytes (control group) and stimulated with 50 ng/ml tumor necrosis factor (TNF-α) for 1 hour (TNF-α group). Then 0.1, 5, 10 μmol/L telmisartan was added to the culture medium for 24 h, respectively(T(0.1, )T(5) and T(10) group). The cells from each group was collected to detect peroxisome proliferator-activated receptors γ (PPARγ) and its phosphorylation level, as well as upstream kinase cell cycle dependent kinase 5 (CDK5) by Western blot. Adiponectin in the culture supernatant was detected by enzyme-linked immunosorbent assay (ELISA). PPARγ or CDK5 of undifferentiated 3T3-L1 adipocytes were silenced by using targeted short hairpin RNA (shRNA). Through infection of the cells with the retrovirus, stabled PPARγ or CDK5 knockdown cell lines were set up and screened by incubation with puromycin. 3T3-L1 adipocyte cell lines expressing serine mutant PPARγ (S273A, S112A, S186A) were obtained and thus their phosphorate sites were further determined. CDK5 knockdown cell lines were detected by oil red O staining to measure the lipid accumulation and differentiation efficiency. The 10 μmol/L telmisartan was used to treat mature CDK5 knockdown 3T3-L1 adipocytes, Western blot was used to detect PPARγ and its phosphorylation level, and ELISA was used to detect the release of adiponectin in the culture supernatant. Results: The TNF-α stimulation had no significant effect on the expression of PPARγ in each group (all P>0.05), but it could up-regulate the phosphorylation of PPARγ in the TNF-α group and down-regulate the release of adiponectin (all P<0.05). Compared with TNF-α group, telmisartan can reduce PPARγ phosphorylation levels and up-regulate adiponectin release in different degrees, among which T(5) group and T(10) group had statistically significant differences (all P<0.05), but for T(0.1) group, the difference was not significant (P>0.05). Compared with the 3T3-L1 wild type (WT) adipocytes, adiponectin in cell line with only S273A mutant did not respond to TNF-α stimulation and telmisartan intervention. Oil red O staining showed that silencing of CDK5 did not affect the differentiation of 3T3-L1 preadipocytes. Western blot results showed that silencing of CDK5 (shCDK5 group) had no significant effect on PPARγ expression (P>0.05), but it could down-regulate the phosphorylation of PPARγ and up-regulate release of adiponectin, compared with the randomized control group (shCon group) and the differences were statistically significant (all P<0.05). Conclusions: Telmisartan can alleviate the increased PPARγ phosphorylation and up-regulation of adiponectin content due to TNF-α stimulation. CDK5 mediates the effect of telmisartan on PPARγ signaling pathway in 3T3-L1 adipocytes. Additonally, it also demonstrated the action site of telmisartan was PPARγ Ser 273, and CDK5 is upstream kinases of PPARγ.

Effects of the food additives sodium acid pyrophosphate, sodium acetate, and citric acid on hemato-immunological pathological biomarkers in rats: Relation to PPAR-α, PPAR-γ and tnfα signaling pathway

The food additives sodium acid pyrophosphate (SAPP), sodium acetate (SA), and citric acid (CA) were evaluated for their hemato-immunotoxic effects. Forty adult Sprague-Dawley rats were distributed into four groups and were orally administered water, SAPP (12.6 mg/kg), CA (180 mg/kg), or SA (13.5 mg /kg) daily for 90 days. Erythrogram and leukogram profiles were evaluated. The levels of lysozyme, nitric oxide, immunoglobulin, and phagocytic activity were measured. Histologic and immunohistochemical evaluations of splenic tissues were performed. Changes in the mRNA expression levels of peroxisome proliferator-activated receptor α and γ (PPAR-α and PPAR-γ), and tumor necrosis factor α (TNF-α) genes were assessed. A significant leukopenic condition was observed with SAPP, while CA induced marked leukocytosis, and SA showed a lymphocytosis condition. Both the innate and humoral parameters were significantly depressed. Various pathological lesions were observed, including diffuse hyperplasia of the red pulp, depletion of the white pulp, and capsular and parenchymal fibrosis. A marked decrease in CD3 T-lymphocyte and CD20 B-lymphocyte immunolabeling in rats treated with SAPP and SA was evident. Marked downregulation of PPAR-α and PPAR-γ together with upregulation of TNF-α was recorded. These results indicate that high doses of SAPP, SA and CA exert hematotoxic and immunotoxic effects with long-term exposure.

Rosiglitazone rescues human neural stem cells from amyloid-beta induced ER stress via PPARγ dependent signaling

Peroxisome proliferator-activated receptor gamma (PPARγ) belongs to a family of ligand-activated nuclear receptors known to regulate many crucial physiological and pathological conditions. Indeed, altered PPARγ transcriptional activity contributes to metabolic syndromes (obesity and hyperglycemia associated with type 2 diabetes mellitus), stroke and neurodegenerative diseases. Various studies suggest that PPARγ agonists influence neuronal deficits in Alzheimer's Disease (AD) patients and rodent models of AD. Expression of amyloid-beta (Aβ), a neuropathological marker associated with the pathogenesis of AD neuronal impairment, is inversely correlated with the activation of PPARγ-dependent neuroprotective responses. Nevertheless, molecular mechanisms by which the effects of PPARγ agonists in AD remain to be clarified. Here, we explore the PPARγ signaling pathways and networks that protect against Aβ-induced endoplasmic reticulum (ER) stress (e.g., caspase 4, Bip, CHOP, ASK1 and ER calcium), cell death (e.g., viability and cytochrome c) and mitochondrial deficiency (e.g., maximal respiratory function, COX activity, and mitochondrial membrane potential) events in the human neural stem cells (hNSCs) treated with Aβ. Co-treatment with GW9662 (an antagonist of PPARγ) effectively blocked these protective effects by rosiglitazone, providing strong evidence that PPARγ-dependent signaling rescues hNSCs from Aβ-mediated toxicity. Together, our data suggest activation of PPARγ pathway might be critical to protecting against AD-related ER stress, ER disequilibrium and mitochondrial deficiency. These findings also improve our understanding of the role of PPARγ in hNSCs, and may aid in the development and implementation of new therapeutic strategies for the treatment of AD.

Dan-Lou Prescription Inhibits Foam Cell Formation Induced by ox-LDL via the TLR4/NF-κB and PPARγ Signaling Pathways.

Atherosclerosis is the major worldwide cause of mortality for patients with coronary heart disease. Many traditional Chinese medicine compound prescriptions for atherosclerosis treatment have been tried in patients. Dan-Lou prescription, which is improved from Gualou-Xiebai-Banxia decoction, has been used to treat chest discomfort (coronary atherosclerosis) for approximately 2,000 years in China. Although the anti-inflammatory activities of Dan-Lou prescription have been proposed previously, the mechanism remains to be explored. Based on the interaction between inflammation and atherosclerosis, we further investigated the effect of Dan-Lou prescription on macrophage-derived foam cell formation and disclosed the underlying mechanisms. In the oxidative low-density lipoprotein (ox-LDL) induced foam cells model using murine macrophage RAW 264.7 cells, the ethanol extract from Dan-Lou prescription (EEDL) reduced ox-LDL uptake and lipid deposition by inhibiting the protein and mRNA expression of Toll-like receptor (TLR)4 and scavenger receptor (SR)B1. After stimulation with ox-LDL, the metabolic profile of macrophages was also changed, while the intervention of the EEDL mainly regulated the metabolism of isovalerylcarnitine, arachidonic acid, cholesterol, aspartic acid, arginine, lysine, L-glutamine and phosphatidylethanolamine (36:3), which participated in the regulation of the inflammatory response, lipid accumulation and cell apoptosis. In total, 27 inflammation-related gene targets were screened, and the biological mechanisms, pathways and biological functions of the EEDL on macrophage-derived foam cells were systemically analyzed by Ingenuity Pathway Analysis system (IPA). After verification, we found that EEDL alleviated ox-LDL induced macrophage foam cell formation by antagonizing the mRNA and protein over-expression of PPARγ, blocking the phosphorylation of IKKα/β, IκBα and NF-κB p65 and maintaining the expression balance between Bax and Bcl-2. In conclusion, we provided evidences that Dan-Lou prescription effectively attenuated macrophage foam cell formation via the TLR4/NF-κB and PPARγ signaling pathways.

Construction of lentiviral RNAi vector of PPARγ gene in cashmere goats and comparison with the transcriptome analysis of adipose cells treatments

As an important trait influencing meat quality, the deposition of Intramuscular fat (IMF) is affected by preadipocyte differentiation. Nuclear receptor peroxisome proliferator-activated receptorγ(PPARγ) plays an important role in the regulation of glucose homeostasis and lipid metabolism. In this study, lentivirus-mediated RNA interference (RNAi) was applied to inhibit PPARγ gene expression, which can explore the effects of PPARγ silencing on the preadipose of cashmere goats in vitro. The roles of PPARγ gene in proliferation and differentiation of adipocytes were investigated by MTT assay and Oil Red O staining extraction assay. Using Real-time PCR and Western blotting analyses, the gene expression levels in goat adipocytes were detected at 24, 36, 48 and 72 h after transfection. By the high-throughput sequencing, the comparative transcriptome analysis of four different samples including preadipocyte, adipocyte, shRNA- PPARγ intramuscular fat cell and control group in Cashmere goats was performed. The results showed that PPARγ gene could increase proliferation of goat adipocyte, but decrease their differentiation. The novel genes screened with 152, 450, 456, 412, 39 and 445 different expressions by high-throughput sequencing. The genes, such as PREF-1, PREF-1, FGF, TGF, TNF, RA, IL-21 and EGF had higher expression in shRNA-PPARγ intramuscular fat cells. The 10 pathways that related to adipocyte differentiation were discovered by GO and KEGG analysis. The most significant pathways involved in PPARγ, WNT, mTOR, and MAPK signaling. Some key gens including LPL, FABP, FATP, AP2, RXRG and CD36 were enriched in PPARγ signal pathway. All of these findings will provide a new reference for understanding adipose transcriptome and identifying novel pathways regulating adipose physiology.

1291 PPAR-γ signaling is dysregulated in keloids

Keloids are exuberant scars in which overgrowths of fibrous tissue extend beyond the borders of the original skin injury. Traumatic insults that can lead to keloids include surgery, piercings, acne, insect bites, and even mild abrasions. These lesions do not regress, and can cause pain, pruritus and psychosocial effects when they appear. Pathway analysis of whole transcriptome data obtained from comparing RNA expression between matched keloid and normal tissue suggests that the PPARγ signaling pathway may be dysregulated in keloids. To investigate this possibility, matched keloid and normal tissue obtained from unrelated patients were used to compare levels of mRNA expression using real-time PCR. FN1, ADAMTS1, and POSTN – all known PPARγ target genes – were found to be dysregulated in expression between keloid tissue and normal skin. Immunohistochemistry and tissue culture experiments are currently being done to determine the location and intensity of the dysregulation of these genes and whether this dysregulation is PPARγ signaling-dependent. As this pathway can inhibit TGFβ signaling, which plays a critical role in fibrosis, further elucidation of this mechanism may lead to developing new forms of treatment.

Suppressive effects of lycopene and β-carotene on the viability of the human esophageal squamous carcinoma cell line EC109.

The molecular mechanisms underlying the chemopreventive effects of carotenoids in different types of cancer are receiving increasing attention. In the present study, the role of peroxisome proliferator-activated receptor γ (PPARγ) in the effect of lycopene and β-carotene on the viability of EC109 human esophageal squamous carcinoma cells was investigated. The viability of EC109 cells was evaluated using MTT assays. The effects of lycopene and β-carotene on the expression of PPARγ, p21WAF1/CIP1, cyclin D1 and cyclooxygenase-2 (COX-2) were analyzed by western blotting. Lycopene and β-carotene (5-40 µM) dose- and time-dependently reduced the viability of the EC109 cells. GW9662, an irreversible PPARγ antagonist, partly attenuated the decrease in EC109 cell viability induced by these carotenoids. Lycopene and β-carotene treatments upregulated the expression of PPARγ and p21WAF1/CIP1, and downregulated the expression of cyclin D1 and COX-2. These modulatory effects of the carotenoid treatments were suppressed by GW9662, suggesting that the inhibition of EC109 cell viability by lycopene and β-carotene involves PPARγ signaling pathways and the modulation of p21WAF1/CIP1, cyclin D1 and COX-2 expression.

Evaluation of the anti-hypertensive effect of Tengfu Jiangya tablet by combination of UPLC-Q-exactive-MS-based metabolomics and iTRAQ-based proteomics technology

ObjectiveTengfu Jiangya tablet (TJT) is a traditional Chinese medicine formulation composed of Uncaria rhynchophylla and Semen raphani. It is a hospital preparation that is widely used in clinics for treating hypertension. A previous metabolomics study reported that TJT exerted a protective effect on hypertension by restoring impaired NO production, ameliorating the inflammatory state, and vascular remodeling. A clinical proteomics study also revealed five key target proteins during TJT intervention. This study aimed to integrate proteome and metabolome data sets for a holistic view of the molecular mechanisms of TJT in treating hypertension. MethodsSerum samples from spontaneously hypertensive rats and Wistar Kyoto rats were analyzed using ultra-high performance liquid chromatography coupled to Q Exactive hybrid quadrupole-Orbitrap mass spectrometry (UPLC-Q-Exactive-MS)-based metabolomics technology and isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics technology. Moreover, we selected two candidate proteins and determined their expression levels in rat serum using an enzyme-linked immunosorbent assay (ELISA). ResultsA total of 20 potential biomarkers and 14 differential proteins in rat serum were identified. These substances were mainly involved in three biological pathways: the kallikrein–kinin pathway, the lipid metabolism pathway, and the PPARγ signaling pathway. ConclusionsThe results suggested that TJT could effectively treat hypertension, partially by regulating the above three metabolic pathways. The combination of proteomics and metabolomics provided a feasible method to uncover the underlying interventional effect and therapeutic mechanism of TJT on spontaneously hypertensive rats.

Betaine promotes lipid accumulation in adipogenic-differentiated skeletal muscle cells through ERK/PPARγ signalling pathway

Betaine, a neutral zwitterionic compound, could regulate intramuscular fat (IMF) deposition and meat quality. However, the efficacy is controversial. Moreover, the regulatory mechanism of betaine on lipid metabolism in skeletal muscle cells remains unclear. Therefore, in this study, we examined the effects and regulatory mechanism of betaine on lipid accumulation in adipogenic-differentiated C2C12 cells. We found that adipogenic-induced C2C12 cells treated with 10mM betaine for 24 and 48h had more lipid accumulation than the control group. Real-time PCR and Western blot results revealed that betaine treatment did not alter the expression of lipolysis and lipid oxidation-related genes, but dramatically increased the expression of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes such as fatty acid binding protein 4 (aP2), fatty acid synthase (FAS) and lipoprteinlipase (LPL). Furthermore, betaine combined with PPARγ inhibitor GW9662 treatment showed that betaine elevated C2C12 lipid accumulation through upregulation of PPARγ. Mechanistically, we found that betaine promoted PPARγ expression and lipid accumulation through inhibition of extracellular regulated protein kinases1/2 (ERK1/2) signalling pathway. These results demonstrate that betaine acts through ERK1/2-PPARγ signalling pathway to regulate lipid metabolism in adipogenic-differentiated skeletal muscle cells, which could provide some useful information for controlling muscle lipid accumulation by manipulating ERK1/2 and PPARγ signalling pathway.

Renoprotective Effect of Danhong Injection on Streptozotocin-Induced Diabetic Rats through a Peroxisome Proliferator-Activated Receptor γ Mediated Pathway.

The aim of the study was to investigate the protective effect of Danhong injection (DHI) on diabetic kidney disease and explore the potential mechanisms. Diabetic kidney disease was induced by unilateral nephrectomy, high-fat diet, and streptozotocin. After DHI administration, the renal function deterioration, 24-hour total urine protein excretion, and elevated serum lipid levels were reversed to some extent, and the renal pathological damage was also ameliorated. The KEGG pathway enrichment analysis demonstrated that the PPARγ signal pathway was significantly upregulated in DH group. And the increased expressions of PPARγ and UCP-1 were confirmed by immunohistochemistry, whereas the p38MAPK was significantly decreased. These data show that DHI could delay the progress of DKD, and the effect might be achieved in part by activating the PPARγ signaling pathway.

Paracrine Wnt5a-β-Catenin Signaling Triggers a Metabolic Program that Drives Dendritic Cell Tolerization

Despite recent advances, many cancers remain refractory to available immunotherapeutic strategies. Emerging evidence indicates that the tolerization of local dendritic cells (DCs) within the tumor microenvironment promotes immune evasion. Here, we have described a mechanism by which melanomas establish a site of immune privilege via a paracrine Wnt5a-β-catenin-peroxisome proliferator-activated receptor-γ (PPAR-γ) signaling pathway that drives fatty acid oxidation (FAO) in DCs by upregulating the expression of the carnitine palmitoyltransferase-1A (CPT1A) fatty acid transporter. This FAO shift increased the protoporphyrin IX prosthetic group of indoleamine 2,3-dioxgenase-1 (IDO) while suppressing interleukin(IL)-6 and IL-12 cytokine expression, culminating in enhanced IDO activity and the generation of regulatory Tcells. We demonstrated that blockade of this pathway augmented anti-melanoma immunity, enhanced the activity of anti-PD-1 antibody immunotherapy, and suppressed disease progression in a transgenic melanoma model. This work implicates a role for tumor-mediated metabolic reprogramming of local DCs in immune evasion and immunotherapy resistance.

Over-expression of PPAR-γ2 gene enhances the adipogenic differentiation of hemangioma-derived mesenchymal stem cells in vitro and in vivo.

BackgroundMost of infantile hemangiomas involute into fibrofatty tissue in childhood, which indicates adipogenesis during this period. Mesenchymal stem cells (MSCs) contribute to the adipogenesis in IH. In this study, we investigated the effects of overexpression of PPAR-γ2 gene on the adipogenic differentiation of Hemangioma-derived MSCs (Hem-MSCs), and discussed the possibility of targeted therapy via PPAR-γ pathway.MethodsMSCs were isolated from proliferating hemangioma by their selective adhesion to plastic culture dishes. Recombinant lentivirus with PPAR-γ2 gene were prepared, and used to transfect Hem-MSCs. Transfected cells were cultured in adipogenic medium to observe the differentiation in vitro. And the cells were mixed with Matrigel, then subcutaneously injected into the back of nude mice to observe the differentiation in vivo.ResultsIn the in vitro tests, Hem-MSCs with overexpression of PPAR-γ2 gene showed enhanced adipogenic differentiation with increased expression of adipogenic-related genes, including PPAR-γ2, ADD1, LPL, and CEBPA genes. In the in vivo tests, Hem-MSCs/Matrigel plugs with overexpression of PPAR-γ2 gene also showed accelerated adipogenesis and time-phased changes of above genes.ConclusionsOverexpression of PPAR-γ2 gene enhances and accelerates the adipogenic differentiation of Hem-MSCs in vitro and in vivo. The results may provide the preliminary evidences for the targeted therapy of IH via PPAR-γ signal pathway.

Lysophospholipid-Related Diseases and PPARγ Signaling Pathway.

The nuclear receptor superfamily includes ligand-inducible transcription factors that play diverse roles in cell metabolism and are associated with pathologies such as cardiovascular diseases. Lysophosphatidic acid (LPA) belongs to a family of lipid mediators. LPA and its naturally occurring analogues interact with G protein-coupled receptors on the cell surface and an intracellular nuclear hormone receptor. In addition, several enzymes that utilize LPA as a substrate or generate it as a product are under its regulatory control. Recent studies have demonstrated that the endogenously produced peroxisome proliferator-activated receptor gamma (PPARγ) antagonist cyclic phosphatidic acid (cPA), which is structurally similar to LPA, inhibits cancer cell invasion and metastasis in vitro and in vivo. We recently observed that cPA negatively regulates PPARγ function by stabilizing the binding of the co-repressor protein, a silencing mediator of retinoic acid, and the thyroid hormone receptor. We also showed that cPA prevents neointima formation, adipocyte differentiation, lipid accumulation, and upregulation of PPARγ target gene transcription. The present review discusses the arbitrary aspects of the physiological and pathophysiological actions of lysophospholipids in vascular and nervous system biology.

Ginsenoside-Rb1-Mediated Anti-angiogenesis via Regulating PEDF and miR-33a through the Activation of PPAR-γ Pathway

Angiogenesis is the formation of new blood vessels from the existing vasculature, which is involved in multiple biological processes, including atherosclerosis, ischemic heart disease, and cancer. Ginsenoside-Rb1 (Rb1), the most abundant ginsenoside isolated form Panax ginseng, has been identified as a promising anti-angiogenic agent via the up-regulation of PEDF. However, the underlying molecular mechanisms still unknown. In the present study, human umbilical vein endothelial cells (HUVECs) were selected to perform in vitro assays. Rb1 (0–20 nM) treatment induced pigment epithelial-derived factor (PEDF) protein expression in concentration and time-dependent manners. Interestingly, it was also demonstrated that the exposure of Rb1 (10 nM) could increase PEDF protein expression without any alteration on mRNA level, suggesting the involvement of posttranscriptional regulation. Furthermore, bioinformatics predictions indicated the regulation of miR-33a on PEDF mRNA 3′-UTR, which was further confirmed by luciferase reporter gene assay and real-time PCR. Over-expression of pre-miR-33a was found to regress partly Rb1-mediated PEDF increment and anti-angiogenic effect in HUVECs. Additionally, Rb1-reduced miR-33a and increased PEDF expression was prevented by pre-incubation with peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist (GW9662) or transfection with PPAR-γ siRNA in HUVECs. Taken together, our findings demonstrated that Rb1 exerted anti-angiogenic effects through PPAR-γ signaling pathway via modulating miR-33a and PEDF expressions. Thus, Rb1 may have the potential of being developed as an anti-angiogenic agent, however, further appropriate studies are warranted to evaluate the effect in vivo.

Microalgae-derived oxylipins decrease inflammatory mediators by regulating the subcellular location of NFκB and PPAR-γ

Oxylipins (OXLs) are bioactive molecules generated by the oxidation of fatty acids that promote the resolution of acute inflammation and prevent chronic inflammatory processes through molecular mechanisms that are not well known. We have previously reported the anti-inflammatory activity of microalgae-derived OXLs and OXL-containing biomass in two inflammatory bowel disease (IBD) models: 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced acute colitis and TNBS-induced recurrent colitis. In this study, we examined the in vitro anti-inflammatory mechanism of action of the most abundant OXLs isolated from Chlamydomonas debaryana (13S-HOTE and 13S-HODE) and Nannochloropsis gaditana (15S-HEPE). These OXLs decreased IL-1β and IL-6 pro-inflammatory cytokines production as well as iNOS and COX-2 expression levels in THP-1 macrophages. In addition, OXLs decreased IL-8 production in HT-29 colon cells, the major chemokine produced by these cells. The interaction of OXLs with NFκB and PPAR-γ signaling pathways was studied by confocal microscopy. In THP-1 macrophages and HT-29 colon cells, stimulated by LPS and TNFα respectively, a pre-treatment with 13S-HOTE, 13S-HODE and 15S-HEPE (100μM) resulted in a lower nuclear presence of NFκB in both cell lines. The study of the subcellular localization of PPAR-γ showed that the treatment of THP-1 and HT-29 cells with these OXLs caused the migration of PPAR-γ into the nucleus. Colocalization analysis of both transcription factors in LPS-stimulated THP-1 macrophages showed that the pre-treatment with 13S-HOTE, 13S-HODE or 15S-HEPE lowered nuclear colocalization similar to control value, and increased cytosolic localization above control level. These results indicate that these OXLs could act as agonist of PPAR-γ and consequently inhibit NFκB signaling pathway activation, thus lowering the production of inflammatory markers, highlighting the therapeutic potential of these OXLs in inflammatory diseases such as IBD.

Curcumin improves glycolipid metabolism through regulating peroxisome proliferator activated receptor γ signalling pathway in high-fat diet-induced obese mice and 3T3-L1 adipocytes.

Curcumin is an active component derived from Curcuma longa L. which is a traditional Chinese medicine that is widely used for treating metabolic diseases through regulating different molecular pathways. Here, in this study, we aimed to comprehensively investigate the effects of curcumin on glycolipid metabolism in vivo and in vitro and then determine the underlying mechanism. Male C57BL/6 J obese mice and 3T3-L1 adipocytes were used for in vivo and in vitro study, respectively. Our results demonstrated that treatment with curcumin for eight weeks decreased body weight, fat mass and serum lipid profiles. Meanwhile, it lowered fasting blood glucose and increased the insulin sensitivity in high-fat diet-induced obese mice. In addition, curcumin stimulated lipolysis and improved glycolipid metabolism through upregulating the expressions of adipose triglyceride lipase and hormone-sensitive lipase, peroxisome proliferator activated receptor γ/α (PPARγ/α) and CCAAT/enhancer binding proteinα (C/EBPα) in adipose tissue of the mice. In differentiated 3T3-L1 cells, curcumin reduced glycerol release and increased glucose uptake via upregulating PPARγ and C/EBPα. We concluded that curcumin has the potential to improve glycolipid metabolism disorders caused by obesity through regulating PPARγ signalling pathway.

Adiponectin promotes preadipocyte differentiation via the PPARγ pathway.

According to the results of a preliminary study, it was hypothesized that the effects of adiponectin (APN) on the improvement of atherosclerosis may be associated with adipocyte differentiation and peroxisome proliferator‑activated receptor γ (PPARγ). The present study simulated the inflammatory environment of epicardial adipose tissue by stimulating mature adipocytes with lipopolysaccharide (LPS); subsequently, the differentiation of 3T3‑L1 preadipocytes was observed. 3T3‑L1 preadipocytes were infected with an adenovirus containing the human adiponectin gene apM1 (Ad‑apM1) and were co‑cultured with mature adipocytes stimulated with LPS. Differentiation into mature adipocytes was initiated using differentiation medium. After 8days, an MTT assay was used to examine cell viability and oil red O staining was used to observe preadipocyte differentiation. In addition, the mRNA expression levels of monocyte chemoattractant protein‑1 (MCP‑1), interleukin (IL)‑6, IL‑8 and tumor necrosis factor α (TNF‑α) were examined by quantitative polymerase chain reaction, and the protein expression levels of PPARγ, CCAAT/enhancer binding protein α (C/EBPα) and preadipocyte factor‑1 (Pref‑1) were measured by western blotting. The results indicated that APN overexpression significantly increased preadipocyte differentiation and cell viability, inhibited MCP‑1, IL‑6, IL‑8 and TNF‑α expression, upregulated PPARγ and C/EBPα expression, and downregulated Pref‑1 under LPS stimulation. In addition, inhibition of PPARγ activity by T0070907 markedly attenuated the effects of APN overexpression. Taken together, the present study demonstrated that the effects of APN on the promotion of preadipocyte differentiation under inflammatory conditions may involve the PPARγ signaling pathway, and at least partly depends on upregulation of PPARγ expression.

MicroRNA-27a-3p suppression of peroxisome proliferator-activated receptor-γ contributes to cognitive impairments resulting from sevoflurane treatment.

Sevoflurane is the most widely used anaesthetic administered by inhalation. Exposure to sevoflurane in neonatal mice can induce learning deficits and abnormal social behaviours. MicroRNA (miR)-27a-3p, a short, non-coding RNA that functions as a tumour suppressor, is up-regulated after inhalation of anaesthetic, and peroxisome proliferator-activated receptor γ (PPAR-γ) is one of its target genes. The objective of this study was to investigate how the miR-27a-3p-PPAR-γ interaction affects sevoflurane-induced neurotoxicity. A luciferase reporter assay was employed to identify the interaction between miR-27a-3p and PPAR-γ. Primary hippocampal neuron cultures prepared from embryonic day 0 C57BL/6 mice were treated with miR-27a-3p inhibitor or a PPAR-γ agonist to determine the effect of miR-27a-3p and PPAR-γ on sevoflurane-induced cellular damage. Cellular damage was assessed by a flow cytometry assay to detect apoptotic cells, immunofluorescence to detect reactive oxygen species, western blotting to detect NADPH oxidase 1/4 and ELISA to measure inflammatory cytokine levels. In vivo experiments were performed using a sevoflurane-induced anaesthetic mouse model to analyse the effects of miR-27a-3p on neurotoxicity by measuring the number of apoptotic neurons using the Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) method and learning and memory function by employing the Morris water maze test. Our results revealed that PPAR-γ expression was down-regulated by miR-27a-3p following sevoflurane treatment in hippocampal neurons. Down-regulation of miR-27a-3p expression decreased sevoflurane-induced hippocampal neuron apoptosis by decreasing inflammation and oxidative stress-related protein expression through the up-regulation of PPAR-γ. In vivo tests further confirmed that inhibition of miR-27a-3p expression attenuated sevoflurane-induced neuronal apoptosis and learning and memory impairment. Our findings suggest that down-regulation of miR-27a-3p expression ameliorated sevoflurane-induced neurotoxicity and learning and memory impairment through the PPAR-γ signalling pathway. MicroRNA-27a-3p may, therefore, be a potential therapeutic target for preventing or treating sevoflurane-induced neurotoxicity.

Clinical Vignettes/Case Reports - Inflammatory Bowel Disease.

Mesalamine (5-aminosalycilic acid) is a first line anti-inflammatory agent used for treatment of inflammatory bowel disease. Mesalamine is thought to reduce colonic inflammation by inhibiting the cyclooxygenase pathway and the γ-form of peroxisomal proliferator-activated receptors (PPAR-γ) signaling pathway. A 30-year-old male with a medical history significant for ulcerative colitis diagnosed 1 year prior, presented with chest pain, fever, chills, and generalized weakness. His symptoms began spontaneously six hours prior to coming to the Emergency room. The patient described a localized chest pain to his mid-sternum, that was sharp, non-radiating, and unalleviated by over-the-counter analgesics. He denied pleurisy, shortness of breath, diaphoresis, palpitations. His chest pain resolved after aspirin 325 mg and 0.5 inch topical nitroglycerin at the emergency department. The patient gave a history of starting budesonide 9 mg QD and an increase in his mesalamine dose from 800 mg to 1600 mg TID, 6 weeks prior. These medication regimen change occurred after an ulcerative colitis flair which developed after the patient had stopped taking his mesalamine for 2 weeks. His initial electrocardiogram showed normal variant study. Chest xray was negative. The case was discussed with his primary gastroenterologist and on-call cardiologist. Considering the strong association of the patients' recent symptoms with increase in his mesalamine dose, only budesonide was continued at admission. Subsequently, TEE showed grade II left ventricular dysfunction and left ventricular ejection fraction of 61 %. After thorough clinical evaluation, the patient was diagnosed with mesalamine-induced-myocarditis, and cardiac catherization was deferred, with recommendations for supportive care. Mesalamine induced-myocarditis is rare. The exact mechanism of which is unclear, but is thought to be secondary to a hypersensitivity reaction rather than direct myocardiotoxicity. This ideology of hypersensitivity myocarditis is supported by cases of acute recurrence of pleuropericarditis with re-exposure to mesalamine. Mesalamine-induced myocarditis has been associated with chronic use, often more than not with a recent increase in dosage in patients who are also concomitantly taking steroids as exemplified in our case. We hope that this report will further increase the awareness of prescribers to myocarditis caused by an increased dosage of mesalamine and with its chronic use.