Cannabinoid CB2 Receptor Potentiates Obesity-Associated Inflammation, Insulin Resistance and Hepatic Steatosis

BACKGROUND: Obesity-associated inflammation is of critical importance in the development of insulin resistance and non-alcoholic fatty liver disease. Since the cannabinoid receptor CB2 regulates innate immunity, the aim of the present study was to investigate its role in obesity-induced inflammation, insulin resistance and fatty liver. METHODOLOGY: Murine obesity models included genetically leptin-deficient ob/ob mice and wild type (WT) mice fed a high fat diet (HFD), that were compared to their lean counterparts. Animals were treated with pharmacological modulators of CB2 receptors. Experiments were also performed in mice knock-out for CB2 receptors (Cnr2 -/-). PRINCIPAL FINDINGS: In both HFD-fed WT mice and ob/ob mice, Cnr2 expression underwent a marked induction in the stromal vascular fraction of epididymal adipose tissue that correlated with increased fat inflammation. Treatment with the CB2 agonist JWH-133 potentiated adipose tissue inflammation in HFD-fed WT mice. Moreover, cultured fat pads isolated from ob/ob mice displayed increased Tnf and Ccl2 expression upon exposure to JWH-133. In keeping, genetic or pharmacological inactivation of CB2 receptors decreased adipose tissue macrophage infiltration associated with obesity, and reduced inductions of Tnf and Ccl2 expressions. In the liver of obese mice, Cnr2 mRNA was only weakly induced, and CB2 receptors moderately contributed to liver inflammation. HFD-induced insulin resistance increased in response to JWH-133 and reduced in Cnr2 -/- mice. Finally, HFD-induced hepatic steatosis was enhanced in WT mice treated with JWH-133 and blunted in Cnr2 -/- mice. CONCLUSION/SIGNIFICANCE: These data unravel a previously unrecognized contribution of CB2 receptors to obesity-associated inflammation, insulin resistance and non-alcoholic fatty liver disease, and suggest that CB2 receptor antagonists may open a new therapeutic approach for the management of obesity-associated metabolic disorder

Microsatellite isolation and marker development in carrot - genomic distribution, linkage mapping, genetic diversity analysis and marker transferability across Apiaceae

<p>Abstract</p> <p>Background</p> <p>The Apiaceae family includes several vegetable and spice crop species among which carrot is the most economically important member, with ~21 million tons produced yearly worldwide. Despite its importance, molecular resources in this species are relatively underdeveloped. The availability of informative, polymorphic, and robust PCR-based markers, such as microsatellites (or SSRs), will facilitate genetics and breeding of carrot and other Apiaceae, including integration of linkage maps, tagging of phenotypic traits and assisting positional gene cloning. Thus, with the purpose of isolating carrot microsatellites, two different strategies were used; a hybridization-based library enrichment for SSRs, and bioinformatic mining of SSRs in BAC-end sequence and EST sequence databases. This work reports on the development of 300 carrot SSR markers and their characterization at various levels.</p> <p>Results</p> <p>Evaluation of microsatellites isolated from both DNA sources in subsets of 7 carrot F₂mapping populations revealed that SSRs from the hybridization-based method were longer, had more repeat units and were more polymorphic than SSRs isolated by sequence search. Overall, 196 SSRs (65.1%) were polymorphic in at least one mapping population, and the percentage of polymophic SSRs across F₂populations ranged from 17.8 to 24.7. Polymorphic markers in one family were evaluated in the entire F₂, allowing the genetic mapping of 55 SSRs (38 codominant) onto the carrot reference map. The SSR loci were distributed throughout all 9 carrot linkage groups (LGs), with 2 to 9 SSRs/LG. In addition, SSR evaluations in carrot-related taxa indicated that a significant fraction of the carrot SSRs transfer successfully across Apiaceae, with heterologous amplification success rate decreasing with the target-species evolutionary distance from carrot. SSR diversity evaluated in a collection of 65 <it>D. carota </it>accessions revealed a high level of polymorphism for these selected loci, with an average of 19 alleles/locus and 0.84 expected heterozygosity.</p> <p>Conclusions</p> <p>The addition of 55 SSRs to the carrot map, together with marker characterizations in six other mapping populations, will facilitate future comparative mapping studies and integration of carrot maps. The markers developed herein will be a valuable resource for assisting breeding, genetic, diversity, and genomic studies of carrot and other Apiaceae.</p

Therapeutic effects of CO-releaser/Nrf2 activator hybrids (HYCOs) in the treatment of skin wound, psoriasis and multiple sclerosis

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Increased Sirt1 secreted from visceral white adipose tissue is associated with improved glucose tolerance in obese Nrf2-deficient mice

International audienceObesity is associated with metabolic dysregulation characterized by insulin resistance and glucose intolerance. Nuclear factor E2-related factor (Nrf2) is a critical regulator of the stress response and Nrf2-deficient mice (Nrf2-/-) are protected against high fat diet (HFD)-induced metabolic derangement. We searched for factors that could underline this favorable phenotype and found that Nrf2-/- mice exhibit higher circulating levels of sirtuin 1 (Sirt1), a key player in cellular homeostasis and energy metabolism, compared to wild-type mice. Increased Sirt1 levels in Nrf2-/- mice were found not only in animals under standard diet but also following HFD. Interestingly, we report here that the visceral adipose tissue (eWAT) is the sole source of increased Sirt1 protein in plasma. eWAT and other fat depots displayed enhanced adipocytes lipolysis, increased fatty acid oxidation and glycolysis, suggesting autocrine and endocrine actions of Sirt1 in this model. We further demonstrate that removal of eWAT completely abolishes the increase in circulating Sirt1 and that this procedure suppresses the beneficial effect of Nrf2 deficiency on glucose tolerance, but not insulin sensitivity, following a HFD regime. Thus, in contrast to many other stressful conditions where Nrf2 deficiency exacerbates damage, our study indicates that up-regulation of Sirt1 levels specifically in the visceral adipose tissue of Nrf2-/- mice is a key adaptive mechanism that mitigates glucose intolerance induced by nutritional stress

HYCO-3, a dual CO-releaser/Nrf2 activator, reduces tissue inflammation in mice challenged with lipopolysaccharide

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Carbon monoxide-induced metabolic switch in adipocytes improves insulin resistance in obese mice

International audienceObesity is characterized by accumulation of adipose tissue and is one the most important risk factors in the development of insulin resistance. Carbon monoxide-releasing (CO-releasing) molecules (CO-RMs) have been reported to improve the metabolic profile of obese mice, but the underlying mechanism remains poorly defined. Here, we show that oral administration of CORM-401 to obese mice fed a high-fat diet (HFD) resulted in a significant reduction in body weight gain, accompanied by a marked improvement in glucose homeostasis. We further unmasked an action we believe to be novel, by which CO accumulates in visceral adipose tissue and uncouples mitochondrial respiration in adipocytes, ultimately leading to a concomitant switch toward glycolysis. This was accompanied by enhanced systemic and adipose tissue insulin sensitivity, as indicated by a lower blood glucose and increased Akt phosphorylation. Our findings indicate that the transient uncoupling activity of CO elicited by repetitive administration of CORM-401 is associated with lower weight gain and increased insulin sensitivity during HFD. Thus, prototypic compounds that release CO could be investigated for developing promising insulin-sensitizing agents

Beneficial paracrine effects of cannabinoid receptor 2 on liver injury and regeneration.

International audienceThe cannabinoid receptor 2 (CB2) plays a pleiotropic role in innate immunity and is a crucial mediator of liver disease. In this study, we investigated the impact of CB2 receptors on the regenerative process associated with liver injury. Following acute hepatitis induced by carbon tetrachloride (CCl(4)), CB2 was induced in the nonparenchymal cell fraction and remained undetectable in hepatocytes. Administration of CCl(4) to CB2(-/-) mice accelerated liver injury, as shown by increased alanine/aspartate aminotransferase levels and hepatocyte apoptosis, and delayed liver regeneration, as reflected by a retarded induction of hepatocyte proliferating cell nuclear antigen expression; proliferating cell nuclear antigen induction was also delayed in CB2(-/-) mice undergoing partial hepatectomy. Conversely, following treatment with the CB2 agonist JWH-133, CCl(4)-treated WT mice displayed reduced liver injury and accelerated liver regeneration. The CCl(4)-treated CB2(-/-) mice showed a decrease in inducible nitric oxide synthase and tumor necrosis factor-alpha expression, and administration of the nitric oxide donor moldomine (SIN-1) to these animals reduced hepatocyte apoptosis, without affecting liver regeneration. Impaired liver regeneration was consecutive to an interleukin-6 (IL-6)-mediated decrease in matrix metalloproteinase 2 (MMP-2) activity. Indeed, CCl(4)-treated CB2(-/-) mice displayed lower levels of hepatic IL-6 messenger RNA and increased MMP-2 activity. Administration of IL-6 to these mice decreased MMP-2 activity and improved liver regeneration, without affecting hepatocyte apoptosis. Accordingly, administration of the MMP inhibitor CTTHWGFTLC to CCl(4)-treated CB2(-/-) mice improved liver regeneration. Finally, in vitro studies demonstrated that incubation of hepatic myofibroblasts with JWH-133 increased tumor necrosis factor-alpha and IL-6 and decreased MMP-2 expressions. CONCLUSION: CB2 receptors reduce liver injury and promote liver regeneration following acute insult, via distinct paracrine mechanisms involving hepatic myofibroblasts. These results suggest that CB2 agonists display potent hepatoprotective properties, in addition to their antifibrogenic effects

The cannabinoid receptor type 2 promotes cardiac myocyte and fibroblast survival and protects against ischemia/reperfusion-induced cardiomyopathy.: CB2 in ischemic cardiomyopathy

International audiencePost-myocardial infarction (MI) heart failure is a major public health problem in Western countries and results from ischemia/reperfusion (IR)-induced cell death, remodeling, and contractile dysfunction. Ex vivo studies have demonstrated the cardioprotective anti-inflammatory effect of the cannabinoid type 2 (CB2) receptor agonists within hours after IR. Herein, we evaluated the in vivo effect of CB2 receptors on IR-induced cell death, fibrosis, and cardiac dysfunction and investigated the target role of cardiac myocytes and fibroblasts. The infarct size was increased 24 h after IR in CB2(-/-) vs. wild-type (WT) hearts and decreased when WT hearts were injected with the CB2 agonist JWH133 (3 mg/kg) at reperfusion. Compared with WT hearts, CB2(-/-) hearts showed widespread injury 3 d after IR, with enhanced apoptosis and remodeling affecting the remote myocardium. Finally, CB2(-/-) hearts exhibited exacerbated fibrosis, associated with left ventricular dysfunction 4 wk after IR, whereas their WT counterparts recovered normal function. Cardiac myocytes and fibroblasts isolated from CB2(-/-) hearts displayed a higher H(2)O(2)-induced death than WT cells, whereas 1 microM JWH133 triggered survival effects. Furthermore, H(2)O(2)-induced myofibroblast activation was increased in CB2(-/-) fibroblasts but decreased in 1 microM JWH133-treated WT fibroblasts, compared with that in WT cells. Therefore, CB2 receptor activation may protect against post-IR heart failure through direct inhibition of cardiac myocyte and fibroblast death and prevention of myofibroblast activation