GQ-11: A new PPAR agonist improves obesity-induced metabolic alterations in LDLr-/- mice.

BACKGROUND: Obesity and insulin resistance/diabetes are important risk factors for cardiovascular diseases and demand safe and efficacious therapeutics. OBJECTIVE: To assess the effects of a new thiazolidine compound-GQ-11-on obesity and insulin resistance induced by a diabetogenic diet in LDL receptor-deficient (LDLr-/-) mice. METHODS: Molecular docking simulations of GQ-11, PPARα and PPARγ structures were performed. Male C57BL/6J LDLr-/- mice fed a diabetogenic diet for 24 weeks were treated with vehicle, GQ-11 or pioglitazone or (20 mg/kg/day) for 28 days by oral gavage. Glucose tolerance test, insulin, HOMA-IR, adipokines (leptin, adiponectin) and the lipid profile were assessed after treatment. Adipose tissue was analysed by X-ray analysis and morphometry; gene and protein expression were evaluated by real-time PCR and western blot, respectively. RESULTS: GQ-11 showed partial agonism to PPARγ and PPARα. In vivo, treatment with GQ-11 ameliorated insulin sensitivity and did not modify subcutaneous adipose tissue and body weight gain. In addition, GQ-11 restored adipokine imbalance induced by a diabetogenic diet and enhanced Glut-4 expression in the adipose tissue. Improved insulin sensitivity was also associated with lower levels of MCP-1 and higher levels of IL-10. Furthermore, GQ-11 reduced triglycerides and VLDL cholesterol and increased HDL-cholesterol by upregulation of Apoa1 and Abca1 gene expression in the liver. CONCLUSION: GQ-11 is a partial/dual PPARα/γ agonist that demonstrates anti-diabetic effects. Additionally, it improves the lipid profile and ameliorates chronic inflammation associated with obesity in atherosclerosis-prone mice.

New thiazolidinediones affect endothelial cell activation and angiogenesis.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor-γ (PPARγ) agonists used in treating type 2 diabetes that may exhibit beneficial pleiotropic effects on endothelial cells. In this study, we characterized the effects of three new TZDs [GQ-32 (3-biphenyl-4-ylmethyl-5-(4-nitro-benzylidene)-thiazolidine-2,4-dione), GQ-169 (5-(4-chloro-benzylidene)-3-(2,6-dichloro-benzyl)-thiazolidine-2,4-dione), and LYSO-7 (5-(5-bromo-1H-indol-3-ylmethylene)-3-(4-chlorobenzyl)-thiazolidine-2,4-dione)] on endothelial cells. The effects of the new TZDs were evaluated on the production of nitric oxide (NO) and reactive oxygen species (ROS), cell migration, tube formation and the gene expression of adhesion molecules and angiogenic mediators in human umbilical vein endothelial cells (HUVECs). PPARγ activation by new TZDs was addressed with a reporter gene assay. The three new TZDs activated PPARγ and suppressed the tumor necrosis factor α-induced expression of vascular cell adhesion molecule 1 and intercellular adhesion molecule 1. GQ-169 and LYSO-7 also inhibited the glucose-induced ROS production. Although NO production assessed with 4-amino-5-methylamino-2',7'-difluorofluorescein-FM probe indicated that all tested TZDs enhanced intracellular levels of NO, only LYSO-7 treatment significantly increased the release of NO from HUVEC measured by chemiluminescence analysis of culture media. Additionally, GQ-32 and GQ-169 induced endothelial cell migration and tube formation by the up-regulation of angiogenic molecules expression, such as vascular endothelial growth factor A and interleukin 8. GQ-169 also increased the mRNA levels of basic fibroblast growth factor, and GQ-32 enhanced transforming growth factor-ß expression. Together, the results of this study reveal that these new TZDs act as partial agonists of PPARγ and modulate endothelial cell activation and endothelial dysfunction besides to stimulate migration and tube formation.

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.

New indole-thiazolidine attenuates atherosclerosis in LDLr(-/-) mice.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor γ (PPARγ) agonists that improve insulin-mediated glucose uptake and possess beneficial vasculoprotective actions. However, because undesirable side effects are associated with these drugs, novel TZDs are under development. In this study, we evaluated the biological activity of LYSO-7, a new indole-thiazolidine, on PPAR activation, inflammation and atherogenesis using a gene reporter assay, lipopolysaccharide (LPS)-activated RAW 264.7 cell culture, and a low-density lipoprotein receptor knockout (LDLr(-/-)) mouse model of atherosclerosis. LYSO-7 shows low cytotoxicity in RAW 264.7 cells and at 2.5µmol/L induces PPARα and PPARγ transactivation as well as inhibits LPS-induced nitrite production and the mRNA gene expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1). In addition, treatment with LYSO-7 reduces the development of atherosclerosis in LDLr(-/-) mice, improves the lipid profile, blood glucose levels, and downregulates CD40 and CD40L expression without affecting the body weight of the animals. Altogether, our data show that LYSO-7 possesses anti-inflammatory properties and that treatment with this TZD attenuates atherosclerosis progression in LDLr(-/-) mice by modulating lipid metabolism and inflammation. Thus, LYSO-7 shows potential as a new drug candidate for the treatment of atherosclerosis.

Hepatic cyclooxygenase-2 expression protects against diet-induced steatosis, obesity, and insulin resistance.

Accumulation evidence links obesity-induced inflammation as an important contributor to the development of insulin resistance, which plays a key role in the pathophysiology of obesity-related diseases such as type 2 diabetes and nonalcoholic fatty liver disease. Cyclooxygenase (COX)-1 and -2 catalyze the first step in prostanoid biosynthesis. Because adult hepatocytes fail to induce COX-2 expression regardless of the proinflammatory stimuli used, we have evaluated whether this lack of expression under mild proinflammatory conditions might constitute a permissive condition for the onset of insulin resistance. Our results show that constitutive expression of human COX-2 (hCOX-2) in hepatocytes protects against adiposity, inflammation, and, hence, insulin resistance induced by a high-fat diet, as demonstrated by decreased hepatic steatosis, adiposity, plasmatic and hepatic triglycerides and free fatty acids, increased adiponectin-to-leptin ratio, and decreased levels of proinflammatory cytokines, together with an enhancement of insulin sensitivity and glucose tolerance. Furthermore, hCOX-2 transgenic mice exhibited increased whole-body energy expenditure due in part by induction of thermogenesis and fatty acid oxidation. The analysis of hepatic insulin signaling revealed an increase in insulin receptor-mediated Akt phosphorylation in hCOX-2 transgenic mice. In conclusion, our results point to COX-2 as a potential therapeutic target against obesity-associated metabolic dysfunction.

Benznidazole blocks NF-kappaB activation but not AP-1 through inhibition of IKK.

Previously, we demonstrated that benznidazole (BZL), known for its antiparasitic action on Trypanosoma cruzi, modulates pro-inflammatory cytokines and NO release in macrophages by inhibiting NF-kappaB. We now proceeded to elucidate the molecular mechanisms by which BZL exerts its inhibitory action on NF-kappaB. We demonstrated that the inhibitory effect of BZL is not extended to other macrophage responses, since it did not inhibit other typical hallmarks of macrophage activation such as phagocytosis, MHC-II molecules expression or production of reactive oxygen species (ROS) by NADPH oxidase. BZL was able to interfere specifically with the activation of NF-kappaB pathway without affecting AP-1 activation in RAW 264.7 macrophages, not only in LPS-mediated activation, but also for other stimuli, such as pro-inflammatory cytokines (IL-1beta, TNF-alpha), PMA or H(2)O(2). Also, BZL delayed the activation of p38 MAPK, but not that of ERK1/2 and JNK. Finally, treatment with BZL inhibited IkappaBalpha phosporylation and hence its degradation, whereas it did not block IkappaB kinase (IKK) alpha/beta phosphorylation. Collectively, BZL behaves as a broad range specific inhibitor of NF-kappaB activation, independently of the stimuli tested.

Bioactivity of nitrolinoleate: effects on adhesion molecules and CD40-CD40L system.

The vascular effects of nitrolinoleate (LNO2), an endogenous product of linoleic acid (LA) nitration by nitric oxide-derived species and a potential nitrosating agent, were investigated on rat endothelial-leukocyte interactions. Confocal microscopy analysis demonstrated that LNO2 was capable to deliver free radical nitric oxide (*NO) into cells, 5 min after its administration to cultured cells, with a peak of liberation at 30 min. THP-1 monocytes incubated with LNO2 for 5 min presented nitrosation of CD40, leading to its inactivation. Other anti-inflammatory actions of LNO2 were observed in vivo by intravital microscopy assays. LNO2 decreased the number of adhered leukocytes in postcapillary venules of the mesentery network. In addition to this, LNO2 reduced mRNA and protein expression of beta2-integrin in circulating leukocytes, as well as VCAM-1 in endothelial cells isolated from postcapillary venules, confirming its antiadhesive effects on both cell types. Moreover, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a nitric oxide scavenger, partially abolished the inhibitory action of LNO2 on leukocyte-endothelium interaction, suggesting that the antiadhesion effects of LNO2 involve a dual role in leukocyte adhesion, acting as a nitric oxide donor as well as through nitric oxide-independent mechanisms. In conclusion, LNO2 inhibited adhesion molecules expression and promoted *NO inactivation of the CD40-CD40L system, both important processes of the inflammatory response.