Dual acting and pan-PPAR activators as potential anti-diabetic therapies

A New Antidiabetic Agent Showing Short- and Long-Term Effects Due to Peroxisome Proliferator-Activated Receptor Alpha/Gamma Dual Agonism and Mitochondrial Pyruvate Carrier Inhibition

A new series of analogues or derivatives of the previously reported PPARα/γ dual agonist LT175 allowed the identification of ligand 10, which was able to potently activate both PPARα and -γ subtypes as full and partial agonists, respectively. Docking studies were performed to provide a molecular explanation for this different behavior on the two different targets. In vivo experiments showed that this compound induced a significant reduction in blood glucose and lipid levels in an STZ-induced diabetic mouse model displaying no toxic effects on bone, kidney, and liver. By examining in depth the antihyperglycemic activity of 10, we found out that it produced a slight but significant inhibition of the mitochondrial pyruvate carrier, acting also through insulin-independent mechanisms. This is the first example of a PPARα/γ dual agonist reported to show this inhibitory effect representing, therefore, the potential lead of a new class of drugs for treatment of dyslipidemic type 2 diabetes.

To Probe Full and Partial Activation of Human Peroxisome Proliferator-Activated Receptors by Pan-Agonist Chiglitazar Using Molecular Dynamics Simulations

Chiglitazar is a promising new-generation insulin sensitizer with low reverse effects for the treatment of type II diabetes mellitus (T2DM) and has shown activity as a nonselective pan-agonist to the human peroxisome proliferator-activated receptors (PPARs) (i.e., full activation of PPARγ and a partial activation of PPARα and PPARβ/δ). Yet, it has no high-resolution complex structure with PPARs and its detailed interactions and activation mechanism remain unclear. In this study, we docked chiglitazar into three experimentally resolved crystal structures of hPPAR subtypes, PPARα, PPARβ/δ, and PPARγ, followed by 3 μs molecular dynamics simulations for each system. Our MM-GBSA binding energy calculation revealed that chiglitazar most favorably bound to hPPARγ (-144.6 kcal/mol), followed by hPPARα (-138.0 kcal/mol) and hPPARβ (-135.9 kcal/mol), and the order is consistent with the experimental data. Through the decomposition of the MM-GBSA binding energy by residue and the use of two-dimensional interaction diagrams, key residues involved in the binding of chiglitazar were identified and characterized for each complex system. Additionally, our detailed dynamics analyses support that the conformation and dynamics of helix 12 play a critical role in determining the activities of the different types of ligands (e.g., full agonist vs. partial agonist). Rather than being bent fully in the direction of the agonist versus antagonist conformation, a partial agonist can adopt a more linear conformation and have a lower degree of flexibility. Our finding may aid in further development of this new generation of medication.

Identification and characterization of phytocannabinoids as novel dual PPARα/γ agonists by a computational and in vitro experimental approach

BACKGROUND

The nuclear Peroxisome Proliferator Activated Receptors (PPARs) are ligand-activated transcription factors playing a fundamental role in energy homeostasis and metabolism. Consequently, functional impairment or dysregulation of these receptors lead to a variety of metabolic diseases. While some phytocannabinoids (pCBs) are known to activate PPARγ, no data have been reported so far on their possible activity at PPARα.

METHODS

The putative binding modes of pCBs into PPARα/γ Ligand Binding Domains were found and assessed by molecular docking and molecular dynamics. Luciferase assays validated in silico predictions whereas the biological effects of such PPARα/γ ligands were assessed in HepG2 and 3T3L1 cell cultures.

RESULTS

The in silico study identified cannabigerolic acid (CBGA), cannabidiolic acid (CBDA) and cannabigerol (CBG) from C. sativa as PPARα/γ dual agonists, suggesting their binding modes toward PPARα/γ isoforms and predicting their activity as full or partial agonists. These predictions were confirmed by luciferase functional assays. The resulting effects on downstream gene transcription in adipocytes and hepatocytes were also observed, establishing their actions as functional dual agonists.

CONCLUSIONS

Our work broadens the activity spectrum of CBDA, CBGA and CBG by providing evidence that these pCBs act as dual PPARα/γ agonists with the ability to modulate the lipid metabolism.

GENERAL SIGNIFICANCE

Dual PPARα/γ agonists have emerged as an attractive alternative to selective PPAR agonists to treat metabolic disorders. We identified some pCBs as dual PPARα/γ agonists, potentially useful for the treatment of dyslipidemia and type 2 diabetes mellitus.

Novel glitazones as PPARγ agonists: molecular design, synthesis, glucose uptake activity and 3D QSAR studies

BACKGROUND

An alarming requirement for finding newer antidiabetic glitazones as agonists to PPARγ are on its utmost need from past few years as the side effects associated with the available drug therapy is dreadful. In this context, herein, we have made an attempt to develop some novel glitazones as PPARγ agonists, by rational and computer aided drug design approach by implementing the principles of bioisosterism. The designed glitazones are scored for similarity with the developed 3D pharmacophore model and subjected for docking studies against PPARγ proteins. Synthesized by adopting appropriate synthetic methodology and evaluated for in vitro cytotoxicity and glucose uptake assay. Illustrations about the molecular design of glitazones, synthesis, analysis, glucose uptake activity and SAR via 3D QSAR studies are reported.

RESULTS

The computationally designed and synthesized ligands such as 2-(4-((substituted phenylimino)methyl)phenoxy)acetic acid derivatives were analysed by IR, ¹H-NMR, ¹³C-NMR and MS-spectral techniques. The synthesized compounds were evaluated for their in vitro cytotoxicity and glucose uptake assay on 3T3-L1 and L6 cells. Further the activity data was used to develop 3D QSAR model to establish structure activity relationships for glucose uptake activity via CoMSIA studies.

CONCLUSION

The results of pharmacophore, molecular docking study and in vitro evaluation of synthesized compounds were found to be in good correlation. Specifically, CPD03, 07, 08, 18, 19, 21 and 24 are the candidate glitazones exhibited significant glucose uptake activity. 3D-QSAR model revealed the scope for possible further modifications as part of optimisation to find potent anti-diabetic agents.

Roles of Peroxisome Proliferator-Activated Receptor Gamma on Brain and Peripheral Inflammation

Peroxisome proliferator-activated receptor gamma (PPARγ) has been implicated in the pathology of numerous diseases involving diabetes, stroke, cancer, or obesity. It is expressed in diverse cell types, including vessels, immune and glial cells, and neurons. PPARγ plays crucial roles in the regulation of cellular differentiation, lipid metabolism, or glucose homeostasis. PPARγ ligands also exert effects on attenuating degenerative processes in the brain, as well as in peripheral systems, and it has been associated with the control of anti-inflammatory mechanisms, oxidative stress, neuronal death, neurogenesis, differentiation, and angiogenesis. This review will highlight key advances in the understanding of the PPARγ-related mechanisms responsible for neuroprotection after brain injuries, both ischemia and traumatic brain injury, and it will also cover the natural and synthetic agonist for PPARγ, angiotensin receptor blockers, and PPARγ antagonists, used in experimental and clinical research. A better understanding of the pleiotropic mechanisms and applications of these drugs to improve the recovery and to repair the acute and chronic induced neuroinflammation after brain injuries will pave the way for more effective therapeutic strategies after brain deficits.

Herbal SGR Formula Prevents Acute Ethanol-Induced Liver Steatosis via Inhibition of Lipogenesis and Enhancement Fatty Acid Oxidation in Mice

Our previous study indicated that herbal SGR formula partially attenuates ethanol-induced fatty liver, but the underlying mechanisms remain unclear. In the present study, mice were pretreated with SGR (100 and 200 mg/kg/d bw) for 30 d before being exposed to ethanol (4.8 g/kg bw). The biochemical indices and histopathological changes were examined to evaluate the protective effects and to explore potential mechanisms by investigating the adiponectin, tumor necrosis factor-α (TNF-α), peroxisome proliferators-activated receptor-α (PPAR-α), sterol regulatory element binding protein-1c (SREBP-1c), adenosine monophosphate-activated protein kinase (AMPK), and so forth. Results showed that SGR pretreatment markedly inhibited acute ethanol-induced liver steatosis, significantly reduced serum and hepatic triglyceride (TG) level, and improved classic histopathological changes. SGR suppressed the protein expression of hepatic SREBP-1c and TNF-α and increased adiponectin, PPAR-α, and AMPK phosphorylation in the liver. Meanwhile, acute toxicity tests showed that no death or toxic side effects within 14 days were observed upon oral administration of the extracts at a dose of 16 g/kg body wt. These results demonstrate that SGR could protect against acute alcohol-induced liver steatosis without any toxic side effects. Therefore, our studies provide novel molecular insights into the hepatoprotective effect of SGR formula, which may be exploited as a therapeutic agent for ethanol-induced hepatosteatosis.

Design, synthesis, and biological evaluation of a series of alkoxy-3-indolylacetic acids as peroxisome proliferator-activated receptor γ/δ agonists

A series of alkoxy-3-indolylacetic acid analogs has been discovered as peroxisome proliferator-activated receptor (PPAR) agonists. Structure-activity relationship study indicated that PPARα/γ/δ activities were dependent on the nature of the hydrophobic group, the attachment position of the alkoxy linker to the indole ring, and N-alkylation of indole nitrogen. Some compounds presented significant PPARγ/δ activity and molecular modeling suggested their putative binding modes in the ligand binding domain of PPARγ. Of these, compound 51 was selected for in vivo study via an evaluation of microsomal stability in mouse and human liver. Compound 51 lowered the levels of fasting blood glucose, insulin, and HbA1c without gain in body weight in db/db mice. When compound 51 was treated, hepatic triglycerides level and the size of adipocytes in white adipose tissue of db/db mice were also reduced as opposed to treatment with rosiglitazone. Taken together, compound 51 shows high potential warranting further studies in models for diabetes and related metabolic disorders and may be in use as a chemical tool for the understanding of PPAR biology.

DisGeNET: a discovery platform for the dynamical exploration of human diseases and their genes

DisGeNET is a comprehensive discovery platform designed to address a variety of questions concerning the genetic underpinning of human diseases. DisGeNET contains over 380 000 associations between >16 000 genes and 13 000 diseases, which makes it one of the largest repositories currently available of its kind. DisGeNET integrates expert-curated databases with text-mined data, covers information on Mendelian and complex diseases, and includes data from animal disease models. It features a score based on the supporting evidence to prioritize gene-disease associations. It is an open access resource available through a web interface, a Cytoscape plugin and as a Semantic Web resource. The web interface supports user-friendly data exploration and navigation. DisGeNET data can also be analysed via the DisGeNET Cytoscape plugin, and enriched with the annotations of other plugins of this popular network analysis software suite. Finally, the information contained in DisGeNET can be expanded and complemented using Semantic Web technologies and linked to a variety of resources already present in the Linked Data cloud. Hence, DisGeNET offers one of the most comprehensive collections of human gene-disease associations and a valuable set of tools for investigating the molecular mechanisms underlying diseases of genetic origin, designed to fulfill the needs of different user profiles, including bioinformaticians, biologists and health-care practitioners. Database URL: http://www.disgenet.org/

Design, synthesis and biological evaluation of a class of bioisosteric oximes of the novel dual peroxisome proliferator-activated receptor α/γ ligand LT175

The effects resulting from the introduction of an oxime group in place of the distal aromatic ring of the diphenyl moiety of LT175, previously reported as a PPARα/γ dual agonist, have been investigated. This modification allowed the identification of new bioisosteric ligands with fairly good activity on PPARα and fine-tuned moderate activity on PPARγ. For the most interesting compound (S)-3, docking studies in PPARα and PPARγ provided a molecular explanation for its different behavior as full and partial agonist of the two receptor isotypes, respectively. A further investigation of this compound was carried out performing gene expression studies on HepaRG cells. The results obtained allowed to hypothesize a possible mechanism through which this ligand could be useful in the treatment of metabolic disorders. The higher induction of the expression of some genes, compared to selective agonists, seems to confirm the importance of a dual PPARα/γ activity which probably involves a synergistic effect on both receptor subtypes.

Natural product agonists of peroxisome proliferator-activated receptor gamma (PPARγ): a review

Agonists of the nuclear receptor PPARγ are therapeutically used to combat hyperglycaemia associated with the metabolic syndrome and type 2 diabetes. In spite of being effective in normalization of blood glucose levels, the currently used PPARγ agonists from the thiazolidinedione type have serious side effects, making the discovery of novel ligands highly relevant.

Natural products have proven historically to be a promising pool of structures for drug discovery, and a significant research effort has recently been undertaken to explore the PPARγ-activating potential of a wide range of natural products originating from traditionally used medicinal plants or dietary sources. The majority of identified compounds are selective PPARγ modulators (SPPARMs), transactivating the expression of PPARγ-dependent reporter genes as partial agonists. Those natural PPARγ ligands have different binding modes to the receptor in comparison to the full thiazolidinedione agonists, and on some occasions activate in addition PPARα (e.g. genistein, biochanin A, sargaquinoic acid, sargahydroquinoic acid, resveratrol, amorphastilbol) or the PPARγ-dimer partner retinoid X receptor (RXR; e.g. the neolignans magnolol and honokiol). A number of in vivo studies suggest that some of the natural product activators of PPARγ (e.g. honokiol, amorfrutin 1, amorfrutin B, amorphastilbol) improve metabolic parameters in diabetic animal models, partly with reduced side effects in comparison to full thiazolidinedione agonists. The bioactivity pattern as well as the dietary use of several of the identified active compounds and plant extracts warrants future research regarding their therapeutic potential and the possibility to modulate PPARγ activation by dietary interventions or food supplements.

Diabetes, oxidative stress and therapeutic strategies

BACKGROUND

Diabetes has emerged as a major threat to health worldwide.

SCOPE OF REVIEW

The exact mechanisms underlying the disease are unknown; however, there is growing evidence that excess generation of reactive oxygen species (ROS), largely due to hyperglycemia, causes oxidative stress in a variety of tissues. Oxidative stress results from either an increase in free radical production, or a decrease in endogenous antioxidant defenses, or both. ROS and reactive nitrogen species (RNS) are products of cellular metabolism and are well recognized for their dual role as both deleterious and beneficial species. In type 2 diabetic patients, oxidative stress is closely associated with chronic inflammation. Multiple signaling pathways contribute to the adverse effects of glucotoxicity on cellular functions. There are many endogenous factors (antioxidants, vitamins, antioxidant enzymes, metal ion chelators) that can serve as endogenous modulators of the production and action of ROS. Clinical trials that investigated the effect of antioxidant vitamins on the progression of diabetic complications gave negative or inconclusive results. This lack of efficacy might also result from the fact that they were administered at a time when irreversible alterations in the redox status are already under way. Another strategy to modulate oxidative stress is to exploit the pleiotropic properties of drugs directed primarily at other targets and thus acting as indirect antioxidants.

MAJOR CONCLUSIONS

It appears important to develop new compounds that target key vascular ROS producing enzymes and mimic endogenous antioxidants.

GENERAL SIGNIFICANCE

This strategy might prove clinically relevant in preventing the development and/or retarding the progression of diabetes associated with vascular diseases.

Association of metabolic syndrome traits and severity of kidney stones: results from a nationwide survey on urolithiasis in Japan

BACKGROUND

Although metabolic syndrome and its individual components have been associated with kidney stone disease, whether the clustering of metabolic syndrome traits increases the severity of kidney stone disease has not been examined in a large-scale study.

STUDY DESIGN

Cross-sectional analysis.

SETTING & PARTICIPANTS

Data were obtained from 30,448 patients enrolled in the 6th Nationwide Survey on Urolithiasis in Japan conducted in 2005. Patients with lower urinary tract stones, struvite stones, cystine stones, or hyperparathyroidism and those younger than 15 years were excluded.

PREDICTOR

Number of metabolic syndrome traits (obesity [body mass index ≥25 kg/m(2)], diabetes, hypertension, and dyslipidemia).

OUTCOMES

Severe form of kidney stone disease, defined as recurrent and/or multiple stones, and abnormalities in urine constituents (hypercalciuria, hyperuricosuria, hyperoxaluria, and hypocitraturia).

RESULTS

11,555 patients were included in the final analyses. Proportions of patients with recurrent and/or multiple stones were 57.7%, 61.7%, 65.2%, 69.3%, and 73.3% with 0, 1, 2, 3, and 4 metabolic syndrome traits, respectively (P < 0.001). There was a significant and stepwise increase in the odds of recurrent and/or multiple stones after adjustment for age and sex. In patients with 4 metabolic syndrome traits, the odds was 1.8-fold greater compared with patients with 0 traits (OR, 1.78; 95% CI, 1.22-2.66). In addition, the presence of metabolic syndrome traits was associated with significantly increased odds of having hypercalciuria, hyperuricosuria, hyperoxaluria, and hypocitraturia after adjustment for age and sex.

LIMITATIONS

Cross-sectional design, absence of dietary data, ill-defined diagnostic criteria for metabolic syndrome traits, and missing data for the majority of participants.

CONCLUSIONS

Metabolic syndrome trait clustering is associated with greater severity of kidney stone disease; increased urinary calcium, uric acid, and oxalate excretion; and decreased urinary citrate excretion. These results suggest that kidney stone disease should be regarded as a systemic disorder linked to metabolic syndrome.

Chronic alcohol-induced hepatic insulin resistance and endoplasmic reticulum stress ameliorated by peroxisome-proliferator activated receptor-δ agonist treatment

BACKGROUND AND AIM

Chronic alcoholic liver disease is associated with hepatic insulin resistance, dysregulated lipid metabolism with increased toxic lipid (ceramide) accumulation, lipid peroxidation, and oxidative and endoplasmic reticulum (ER) stress. Peroxisome-proliferator activated receptor (PPAR) agonists are insulin sensitizers that can restore hepatic insulin responsiveness in both alcohol and non-alcohol-related steatohepatitis. Herein, we demonstrate that treatment with a PPAR-δ agonist enhances insulin signaling and reduces the severities of ER stress and ceramide accumulation in an experimental model of ethanol-induced steatohepatitis.

METHODS

Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% or 37% ethanol (caloric) for 8 weeks. After 3 weeks on the diets, rats were treated with vehicle or PPAR-δ agonist twice weekly by i.p. injection.

RESULTS

Ethanol-fed rats developed steatohepatitis with inhibition of signaling through the insulin and insulin-like growth factor-1 receptors, and Akt activated pathways. Despite continued ethanol exposure, PPAR-δ agonist co-treatments increased Akt activation, reduced multiple molecular indices of ER stress and steatohepatitis.

CONCLUSIONS

These results suggest that PPAR-δ agonist rescue of chronic alcoholic liver disease is mediated by enhancement of insulin signaling through Akt/metabolic pathways that reduce lipotoxicity and ER stress.

Nr4a1 is required for fasting-induced down-regulation of Pparγ2 in white adipose tissue

Expression of the nuclear receptor gene, Nur77 (Nr4a1), is induced in white adipose tissue (WAT) in response to β-adrenergic stimulation and fasting. Recently, Nur77 has been shown to play a gene regulatory role in the fasting response of several other major metabolic tissues. Here we investigated the effects of Nur77 on the WAT transcriptome after fasting. For this purpose, we performed gene expression profiling of WAT from wild-type and Nur77(-/-) mice submitted to prolonged fasting. Results revealed Nur77-dependent changes in expression profiles of 135 transcripts, many involved in insulin signaling, lipid and fatty acid metabolism, and glucose metabolism. Network analysis identified the deregulated genes Pparγ2 and Nur77 as central hubs and closely connected in the network, indicating overlapping biological function. We further assayed the expression level of Pparγ2 in a bigger cohort of fasted mice and found a significant Nur77-dependent down-regulation of Pparγ2 in the wild-type mice (P = 0.021, n = 10). Consistently, the expression of several known Pparγ2 targets, found among the Nur77-regulated genes (i.e. G0s2, Grp81, Fabp4, and Adipoq), were up-regulated in WAT of fasted Nur77(-/-) mice. Finally, we show with chromatin immunoprecipitation and luciferase assays that the Pparγ2 promoter is a direct target of Nurr-related 77-kDa protein (Nur77)-dependent repressive regulation and that the N-terminal domain of Nur77 is required for this regulation. In conclusion, we present data implicating Nur77 as a mediator of fasting-induced Pparγ2 regulation in WAT.

A neutral risk on the development of new-onset diabetes mellitus (NODM) in Taiwanese patients with dyslipidaemia treated with fibrates

There are no data on the incidence of new-onset diabetes mellitus (NODM ) in nondiabetic dyslipidaemia patients treated with fibrates. The aim of our study was to clarify these issues, to investigate the relationship between NODM and fibrate and whether the fibrates lead to increased risk for developing NODM. A retrospective cohort study was conducted by analyzing the Longitudinal Health Insurance Database (LHID 2005) of the National Health Insurance Research Database (NHIRD) from 2005 to 2010 to investigate all fibrate prescriptions for patients with dyslipidaemia. We estimated the hazard ratios (HRs) of NODM associated with fibrate use. We identified 145 NODM patients among 3,815 dyslipidaemic patients in the database for the study period. The risk estimates for NODM for users of fenofibrate (HR 1.30; 95% CI 0.82, 2.05) and gemfibrozil (HR 0.771; 95% CI 0.49, 1.22) were not associated with an increased risk of developing NODM (P > 0.05). Our results revealed that patients with dyslipidaemia who took fenofibrate and gemfibrozil had a neutral risk of NODM. The reasons may be associated with the fibrates have the properties that activate PPARα and in some cases also activated PPARγ, leading to showing a neutral risk of NODM.

Emerging PPARγ-Independent Role of PPARγ Ligands in Lung Diseases

Peroxisome proliferator activated receptor (PPAR)-γ is a nuclear hormone receptor that is activated by multiple agonists including thiazolidinediones, prostaglandins, and synthetic oleanolic acids. Many PPARγ ligands are under investigation as potential therapies for human diseases. These ligands modulate multiple cellular pathways via both PPARγ-dependent and PPARγ-independent mechanisms. Here, we review the role of PPARγ and PPARγ ligands in lung disease, with emphasis on PPARγ-independent effects. PPARγ ligands show great promise in moderating lung inflammation, as antiproliferative agents in combination to enhance standard chemotherapy in lung cancer and as treatments for pulmonary fibrosis, a progressive fatal disease with no effective therapy. Some of these effects occur when PPARγ is pharmaceutically antagonized or genetically PPARγ and are thus independent of classical PPARγ-dependent transcriptional control. Many PPARγ ligands demonstrate direct binding to transcription factors and other proteins, altering their function and contributing to PPARγ-independent inhibition of disease phenotypes. These PPARγ-independent mechanisms are of significant interest because they suggest new therapeutic uses for currently approved drugs and because they can be used as probes to identify novel proteins and pathways involved in the pathogenesis or treatment of disease, which can then be targeted for further investigation and drug development.

Developmental programming: prenatal and postnatal contribution of androgens and insulin in the reprogramming of estradiol positive feedback disruptions in prenatal testosterone-treated sheep

Prenatal testosterone (T) excess compromises the estradiol (E(2)) positive feedback. This study tested the hypothesis that antagonizing androgen action or improving insulin sensitivity prenatally would prevent positive feedback disruptions from developing, whereas postnatal intervention with androgen antagonist or insulin sensitizer would ameliorate the severity of disruptions in prenatal T-treated females. The E(2) positive feedback response was tested at 16 wk of age in the following groups of animals: 1) control, 2) prenatal T, 3) prenatal T plus the androgen antagonist, flutamide, 4) prenatal T plus insulin sensitizer, rosiglitazone, 5) prenatal T and postnatal androgen antagonist, and 6) prenatal T and postnatal insulin sensitizer (n = 7-21 animals/group). Prenatal T treatment involved the administration of T propionate (100 mg, im) twice weekly from d 30 to 90 of gestation. Prenatal interventions involved daily sc administration of androgen antagonist (15 mg/kg) or oral administration of insulin sensitizer (8 mg) for the same duration. Postnatal treatments began at 8 wk of age and involved daily oral administration of androgen antagonist (15 mg/kg) or insulin sensitizer (0.11 mg/kg). None of the prenatal/postnatal interventions increased number of animals responding or prevented the time delay in LH surge response to the E(2) positive feedback challenge. In contrast, the postnatal treatment with androgen antagonist or insulin sensitizer increased total LH released in response to E(2) positive feedback challenge, compared with the T animals. Overall, these interventional studies indicate that timing and magnitude of the LH surge are programmed by different neuroendocrine mechanisms with postnatal androgens and insulin determining the size and prenatal estrogen likely the timing of the LH surge.

Vascular effects of glycoprotein130 ligands--part II: biomarkers and therapeutic targets

Glycoprotein130 (gp130) ligands are defined by the use of the common receptor subunit gp130 and comprise interleukin (IL)-6, oncostatin M (OSM), IL-11, leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), ciliary neurotrophic factor (CNTF), IL-27 and neuropoietin (NP). In part I of this review we addressed the pathophysiological functions of gp130 ligands with respect to the vascular wall. In part II of this review on the vascular effects of gp130 ligands we will discuss data about possible use of these molecules as biomarkers to predict development or progression of cardiovascular diseases. Furthermore, the possibility to modulate circulating levels of gp130 ligands or their tissue expression by specific antibodies, soluble gp130 protein, renin-angiotensin-aldosterone system (RASS) inhibitors, statins, agonists of peroxisome proliferator-activated receptors (PPAR), hormone replacement therapy, nonsteroidal anti-inflammatory drugs (NSAID) or lifestyle modulating strategies are presented. Recent knowledge about the application of recombinant cytokines from the gp130 cytokine family as therapeutic agents in obesity or atherosclerosis is also summarized. Thus the purpose of this review is to cover a possible usefulness of gp130 ligands as biomarkers and targets for therapy in cardiovascular pathologies.

Structural Correlates of PPAR Agonist Rescue of Experimental Chronic Alcohol-Induced Steatohepatitis

Chronic alcoholic liver disease is associated with hepatic insulin resistance, inflammation, oxidative and ER stress, mitochondrial dysfunction, and DNA damage. Peroxisome-proliferator activated receptor (PPAR) agonists are insulin sensitizers that have anti-inflammatory/anti-oxidant effects. We previously showed that PPAR agonists can restore hepatic insulin responsiveness in chronic ethanol-fed rats with steatohepatitis. Herein, we furthered our investigations by characterizing the histological and ultrastructural changes mediated by PPAR agonist rescue of alcohol-induced steatohepatitis. Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% or 37% ethanol (caloric) for 8 weeks. After 3 weeks on the diets, rats were treated with vehicle, or a PPAR-α, PPAR-δ, or PPAR-γ agonist twice weekly by i.p. injection. Ethanol-fed rats developed steatohepatitis with disordered hepatic chord architecture, mega-mitochondria, disruption of the RER, increased apoptosis, and increased 4-hydroxynonenal (HNE) and 3-nitrotyrosine (NTyr) immunoreactivity. PPAR-δ and PPAR-γ agonists reduced the severity of steatohepatitis, and restored the hepatic chord-like architectural, mitochondrial morphology, and RER organization, and the PPAR-δ agonist significantly reduced hepatic HNE. On the other hand, prominent RER tubule dilation, which could reflect ER stress, persisted in ethanol-exposed, PPAR-γ treated but not PPAR-δ treated livers. The PPAR-α agonist exacerbated both steatohepatitis and formation of mega-mitochondria, and it failed to restore RER architecture or lower biochemical indices of oxidative stress. In conclusion, improved hepatic insulin responsiveness and decreased inflammation resulting from PPAR-δ or PPAR-γ agonist treatments of alcohol-induced steatohepatitis are likely mediated by enhanced signaling through metabolic pathways with attendant reductions in ER stress, oxidative stress, and mitochondrial dysfunction.