Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied. A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8 weeks. After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis. Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

RYGB consists of the Roux limb (RL), the biliopancreatic limb (BPL), and the common channel (CC). There is no consensus on the optimal limb lengths. Using a mouse model of RYGB, 30 diet-induced obese mice were divided into two groups with varying BPL and CC lengths: a standard BPL with a long CC (RYGB S) and a long BPL with a short CC (RYGB L). Additionally, 9 age-matched, lean control mice (LC) were also included in this study. RYGB S had limb lengths of RL = 17

Bariatric surgery is emerging as an effective treatment for obesity and the metabolic syndrome. Recently, we demonstrated that Roux-en-Y gastric bypass (RYGB), but not vertical sleeve gastrectomy (VSG), resulted in improvements to white adipose physiology and enhanced brown adipose functioning. Since beneficial alterations to liver health are also expected after bariatric surgery, comparing the post-operative effects of RYGB and VSG on liver physiology is essential to their application in the treatment of non-alcoholic fatty liver disease (NAFLD). The effects of RYGB and VSG on liver physiology were compared using diet induced mouse model of obesity. High-fat diet (HFD) was administered for 12 weeks after surgery and alterations to liver physiology were assessed. Both RYGB and VSG showed decreased liver weight as well as reductions to hepatic cholesterol and triglyceride levels. There were demonstrable improvements to NAFLD activity score (NAS) and fibrosis stage scoring after both surgeries. In RYGB, these beneficial changes to liver function resulted from the downregulation of pro-fibrotic and upregulation anti-fibrotic genes, as well as increased fatty acid oxidation and bile acid flux. For VSG, though similar alterations were observed, they were less potent. However, VSG did significantly downregulate pro-fibrotic genes and showed increased glycogen content paralleled by decreased glycogenolysis which may have contributed to the resolution of NAFLD. RYGB and VSG improve liver physiology and function, but RYGB is more efficacious. Resolutions of NAFLD in RYGB and VSG are achieved through different processes, independent of weight loss.

Adipose dysfunction is the primary defect in obesity that contributes to the development of dyslipidemia, insulin resistance, cardiovascular diseases, type 2 diabetes, non-alcoholic fatty liver disease (NAFLD) and some cancers. Previously, we demonstrated the development of NAFLD in lipocalin-type prostaglandin D2 synthase (L-PGDS) knockout mice regardless of diet. In the present study, we examined the role of L-PGDS in adipose in response to a high fat diet. We observed decreased expression of L-PGDS in adipose tissue and concomitant lower plasma levels in a dietary model of obesity as well as in insulin resistant 3T3-L1 adipocytes. We show reduced adiponectin expression and phosphorylation of AMPK in white adipose tissue of L-PGDS KO mice after 14 weeks on a high fat diet as compared to control C57BL/6 mice. We also observe an increased fat content in L-PGDS KO mice as demonstrated by adipocyte hypertrophy and increased expression of lipogenenic genes. We confirmed our in vivo findings in in vitro 3T3-L1 adipocytes, using an enzymatic inhibitor of L-PGDS (AT56). Rosiglitazone treatment drastically increased L-PGDS expression in insulin resistant 3T3-L1 adipocytes and increased adiponectin expression and AMPK phosphorylation in AT56 treated 3T3-L1 adipocytes. We conclude that the absence of L-PGDS has a deleterious effect on adipose tissue functioning, which further reduces insulin sensitivity in adipose tissue. Consequently, we propose L-PGDS appears to function as a potential member of the adipokine secretome involved in the regulation of the obesity-associated metabolic syndrome.

PURPOSE:Understanding the effects of Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) on adipose tissue physiology is important for the treatment of obesity-related metabolic disorders. By using robust mouse models of bariatric surgery that closely resemble those performed in humans, we can compare the effects of RYGB and VSG on adipose physiology in the absence of post-operative confounds such as diet and lifestyle changes.MATERIALS AND METHODS:RYGB and VSG were compared using a diet-induced mouse model of obesity. High-fat diet (HFD) was administered post-operatively and changes to white and brown adipose tissue were evaluated, along with alterations to weight, glucose homeostasis, dyslipidemia, and insulin sensitivity.RESULTS:After prolonged exposure to high-fat diet post-operatively, RYGB was effective in achieving sustained weight loss, while VSG unexpectedly accelerated weight gain rates. The resolution of obesity-related comorbidities such as glucose and insulin intolerance, dyslipidemia, and insulin sensitivity was improved after RYGB, but not for VSG. In RYGB, there were improvements to the function and health of white adipose tissue, enhanced brown adipose metabolism, and the browning of subcutaneous white adipose tissue, with no comparable changes seen for these factors after VSG. Some markers of systemic inflammation improved after both RYGB and VSG.CONCLUSION:There are significantly different effects between RYGB and VSG when HFD is administered post-operatively and robust mouse models of bariatric surgery are used. RYGB resulted in lasting physiological and metabolic changes but VSG showed little difference from that of its sham-operated, DIO counterpart.

Non-alcoholic fatty liver disease (NAFLD) is an emerging risk factor for type 2 diabetes mellitus, cardiovascular disease, and all-cause mortality. Previously, we demonstrated that lipocalin-type prostaglandin D2 synthase (L-PGDS) knockout mice show increased glucose intolerance and accelerated atherosclerosis. In the present study, we investigated the role of L-PGDS in mediating NAFLD utilizing L-PGDS knockout (KO) and control C57BL/6 mice fed either low fat (LFD) or high fat diet (HFD) for 14 weeks. Our present study demonstrates that L-PGDS KO mice remain slightly lighter in weight compared to control mice, yet develop NAFLD faster and eventually progress to the more severe non-alcoholic steatohepatitis (NASH). We found increased lipid accumulation in the liver of KO mice over time on both diets, as compared to control mice. The L-PGDS KO mice showed elevated fasting glucose and insulin levels and developed insulin resistance on both LFD and HFD. Lipogenesis marker proteins such as SREBP-1c and LXRα were increased in L-PGDS KO mice after 14 weeks on both diets, when compared to control mice. We replicated our in vivo findings in vitro using HepG2 cells treated with a combination of free fatty acids (oleic and palmitic acid) and exposure to a L-PGDS inhibitor and prostaglandin D2 receptor (DP1) antagonists. We conclude that the absence or inhibition of L-PGDS results in dyslipidemia, altered expression of lipogenesis genes and the acceleration of NAFLD to NASH, independent of diet and obesity. We propose L-PGDS KO mice as a useful model to explore the pathogenesis of NAFLD and NASH, and L-PGDS as a potential therapeutic target for treatment.

Background/objective: Lipocalin Prostaglandin D2 synthase (LPGDS) contributes to the production of PGD2, which has been associated with adipogenesis. In this study, we aimed to investigate the role of PGD2 on obesity through its DP1 and DP2 receptor signaling using intraperitoneal injection of their respective agonists and antagonists. Methods: ApoE(-/-) mice were divided into five groups: vehicle control (n = 5}, DP1 receptor agonist (n = 5), DP1 receptor antagonist (n = 5), DP2 receptor agonist (n = 5), and DP2 receptor antagonist (n = 5), and the study was carried out for 10 weeks. Results: Despite being on high fat diet, mice receiving DP1 receptor agonist sustained a significant inhibition of weight gain throughout the study gaining only 11.4% body weight compared to the controls gaining 61% body weight. Interestingly, parallel to the body weight, the DP1 receptor agonist group showed a significant reduction in food intake throughout the study. Consistently, fasting leptin, insulin and bile acids levels were elevated in the DP1 receptor agonist group compared to controls. As expected, there was a significant reduction in fasting glucose level in DP1 receptor agonist group. At last, as a result of weight gain inhibition, DP1 receptor agonist also imparted cardiovascular benefits showing significant reduction in aortic wall thickness, intima, adventia and lumen size. Conclusion: Based on the obtained results, we believe DP1 receptor agonism inhibited diet induced weight gain possibly through controlling appetite which consequently imparted beneficial cardiometabolic effects. DP1 receptor agonism may represent a novel therapeutic target for the management of obesity. (c) 2017 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

BACKGROUND:Glucagon-like peptide-1 (GLP-1) level was significantly increased post Vertical Sleeve Gastrectomy (VSG), an effect believed to contribute to its beneficial cardiometabolic effects. OBJECTIVE:To validate the beneficial GLP-1 mediated cardiometabolic effects post VSG using GLP-1 antagonist (exendin 9-39) in Zucker diabetic fatty rats. METHODS:Animals were divided into three (n = 5) groups: (i) sham, (ii) VSG, and (iii) VSG received exendin 9-39 (GLP-1 receptor antagonist). The study was performed over 12 weeks and parameters were measured 12 weeks post-surgery. RESULTS AND DISCUSSION:As expected, fasting blood glucose and insulin levels were improved post VSG due to enhanced GLP-1 secretion. However, both fasting glucose and insulin levels were impaired in the presence of GLP-1 antagonist. Baseline total cholesterol level pre-surgery was 100±1 mg/dl which remained unchanged in the VSG group but significantly increased to 140±8 mg/dl in the presence of antagonist. Interestingly, post-surgery there was a nearly 70% reduction in triglyceride level in the VSG group compared to sham which was overcome in the presence of antagonist. Myographic studies using aortic rings showed no significant change between groups. Additionally, blood pressure and heart rate also remained unchanged in all groups. Serum bile acid and L-PGDS levels increased post VSG but significantly decreased in the presence of antagonist, suggesting a strong association with GLP-1 and a novel mechanism of action. CONCLUSION:Enhanced GLP-1 secretion post VSG imparted beneficial cardiometabolic effects on blood glucose, insulin, total cholesterol, triglyceride, bile acids and L-PGDS levels which were abated in the presence of GLP-1 antagonist.

Background: Roux-en-Y gastric bypass (RYGB) may improve cardiometabolic risk through alteration of bile acids and L-PGDS levels. Objective: The objective of this study was to investigate the effect of RYGB on aortic wall thickness, in relation to bile acid and L-PGDS metabolism.Methods: Zucker diabetic fatty (ZDF) rats were divided into two groups, ad lib (n = 4), and RYGB (n = 6). Bile acid and L-PGDS were measured presurgery and fourteen weeks post-surgery.Results: Elevation of bile acid levels following RYGB in Zucker Diabetic Fatty (ZDF) rodents was observed, as compared to ad lib. RYGB in ZDF rodents led to a significantly decreased aortic wall thickness (25%) as compared to ad lib control. Although bile acid metabolism is implicated in these alterations, other mediators are likely involved. Our laboratory has demonstrated lipocalin prostaglandin D2 synthase (L-PGDS) is a kno n cardiometabolic modulator that also functions as a bile acid binding protein. Therefore, L-PGDS levels were measured and a significant elevation was observed with RYGB compared to ad lib control.Conclusion: Based on these findings, RYGB showed beneficial effect on aorticwall thickness, possibly through bile acids and L-PGDS elevation in a severely obese and diabetic rodent model. (C) 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

The objective of the study was to investigate the role of prostaglandin D2 during pregnancy and its mediator Lipocalin-type prostaglandin D2 synthase (L-PGDS) as a predictor of preterm birth (PTB). Transgenic L-PGDS (+/+), L-PGDS (-/-) and C57BL/6 control pregnant mice models were used to determine the effect of DP1 and DP2 receptor antagonists in lipopolysaccharide (LPS)-induced PTB mice. In addition, L-PGDS levels were measured in the cervicovaginal secretions (CVS) of 370 pregnant women using ELISA and further processed for isoform detection using 2-D gel electrophoresis. Our results found that C57BL/6 control mice (n = 26), transgenic L-PGDS (+/+) (n = 26), demonstrated an 89% and 100% preterm birth in LPS (intraperitoneal injection, 20mg/kg) induced mice model respectively. Interestingly, the incidence of PTB was significantly reduced to 40% in L-PGDS (-/-) knockout mice (n = 26). DP1 and DP2 receptor antagonists (0.264 μg/day, dose of 0.1 μg/μl with the flow of 0.11 μl/h for 28 day using Alzet pumps) were used to investigate the effect in LPS-induced PTB in C57BL/6 mice and found 3.3-fold increase in viable pups after LPS-induction. In addition, L-PGDS levels were measured in CVS samples and found that PTB women (n = 296) had two-fold higher levels compared to full term births (n = 74) and established a significant inverse correlation between levels of L-PGDS and days to expected delivery by using 370 preterm birth CVS samples. Elevated L-PGDS levels in the CVS of women may be considered as a potential biomarker for PTB in future. Secondly, the use of DP1 and DP2 receptor antagonists may represent novel tocolytic agents for the treatment of PTB.

Diabetes is associated with disturbances in the normal levels of both insulin and glucagon, both of which play critical roles in the regulation of glycemia. Recent studies have found lipocalin-type prostaglandin D2 synthase (l-PGDS) to be an emerging target involved in the pathogenesis of type-2 diabetes. This study focused on the effect of l-PGDS on glucagon secretion from cultured pancreatic Alpha TC-1 Clone 6 cells. When cells were treated with various concentrations of l-PGDS (0, 10, 50, and 100 ug/ml) for 2 h in 1 mM glucose; glucagon secretion decreased to 670±45, 838±38, 479±11, and 437±45 pg/ml, respectively. In addition, pancreatic islets were isolated from C57BL/6 mice and stained for prostaglandin D2 receptors, DP1 and DP2, using immunohistochemistry. Our results showed that these islets express only the DP1 receptor. Pancreatic islets were then stained for alpha and beta cells, as well as DP1, to find the primary location of the receptor within the islets using immunofluorescence. Interestingly, DP1 receptor density was found primarily in alpha cells rather than in beta cells. Our study is the first to report a correlation between l-PGDS and glucagon secretion in alpha cells. Based on our obtained results, it can be concluded that higher concentrations of l-PGDS significantly reduced the secretion of glucagon in alpha cells, which may contribute to the pathogenesis of diabetes as well as offer a novel therapeutic site for the treatment of diabetes.

BACKGROUND:Roux-en-Y gastric bypass (RYGB) ameliorates type 2 diabetes (T2DM) and obesity through alteration in gastrointestinal (GI) hormones.OBJECTIVE:The objective of this study was to investigate the effect of RYGB on GI hormones and cardiometabolic parameters in Zucker diabetic fatty (ZDF) rodents.SETTING:Winthrop University Hospital, Research and Academic CenterMETHODS:Animals were divided into 3 groups, pair-fed (n = 4), ad lib (n = 4), and RYGB (n = 5). This study was carried out for 4 weeks and all related parameters were measured pre- and postsurgery in fasted obese diabetic Zucker rodents.RESULTS:Postoperatively, RYGB significantly decreased fasting blood glucose by 32% compared with ad lib. Plasma insulin and leptin levels were also found to be significantly decreased, by 66% and 38%, respectively, after surgery. Moreover, both glucose-dependent insulinotropic polypeptide (GIP) and peptide tyrosine-tyrosine (PYY) were significantly increased after RYGB-by 300% and 51%, respectively. Glucagon-like peptide-1 (GLP-1) levels were also increased, but the increase was not statistically significant. Total cholesterol levels of the RYGB group remained unchanged for 4 weeks. However, total cholesterol in the ad lib and pair-fed groups increased by 25% and 34%, respectively, compared with initial levels. The cholesterol/high-density lipoprotein (HDL) ratio was decreased in the RYGB group by 14% and 30% compared with the ad lib and pair-fed group, respectively. The RYGB group had a significant decrease in aortic wall thickness of 25% compared with the ad lib and pair-fed groups. Similarly, the RYGB group had a 20-unit (mm Hg) decrease in systolic blood pressure compared with the presurgical value.CONCLUSION:RYGB has beneficial cardiometabolic effects through alterations in GI hormones in a severely obese and diabetic rodent model.

The steroid receptor coactivator 1 (SRC1) regulates key metabolic pathways, including glucose homeostasis. SRC1(-/-) mice have decreased hepatic expression of gluconeogenic enzymes and a reduction in the rate of endogenous glucose production (EGP). We sought to determine whether decreasing hepatic and adipose SRC1 expression in normal adult rats would alter glucose homeostasis and insulin action. Regular chow-fed and high-fat-fed male Sprage-Dawley rats were treated with an antisense oligonucleotide (ASO) against SRC1 or a control ASO for 4 wk, followed by metabolic assessments. SRC1 ASO did not alter basal EGP or expression of gluconeogenic enzymes. Instead, SRC1 ASO increased insulin-stimulated whole body glucose disposal by ~30%, which was attributable largely to an increase in insulin-stimulated muscle glucose uptake. This was associated with an approximately sevenfold increase in adipose expression of lipocalin-type prostaglandin D2 synthase, a previously reported regulator of insulin sensitivity, and an approximately 70% increase in plasma PGD2 concentration. Muscle insulin signaling, AMPK activation, and tissue perfusion were unchanged. Although GLUT4 content was unchanged, SRC1 ASO increased the cleavage of tether-containing UBX domain for GLUT4, a regulator of GLUT4 translocation. These studies point to a novel role of adipose SRC1 as a regulator of insulin-stimulated muscle glucose uptake.

Previously, we demonstrated that lipocalin-type prostaglandin D(2) synthase (L-PGDS) induces apoptosis and prevents cell cycle progression in several cell types. In this study we determined the expression of L-PGDS in a variety of human lung tumor types. While L-PGDS expression was evident in the surrounding margins, we observed significantly decreased protein and gene expression in the tumor tissue. Using RT-PCR we demonstrated that L-PGDS gene expression decreased proportionately with tumor progression. In addition, we demonstrated that exogenously added L-PGDS could suppress the hyperproliferation and PDGF-stimulated migration of A549 cells, a cultured carcinomic human alveolar basal epithelial cell line. We conclude that L-PGDS may play a key role in modulating lung cancer growth and may offer a novel diagnostic and therapeutic approach for treatment.