Ultrasound-Targeted Microbubble Destruction Mediates Gene Transfection for Beta-Cell Regeneration and Glucose Regulation.

Ultrasound-targeted microbubble destruction (UTMD) mediates gene transfection with high biosafety and thus has been promising toward treatment of type 1 diabetes. However, the potential application of UTMD in type 2 diabetes (T2D) is still limited, due to the lack of systematic design and dynamic monitoring. Herein, an efficient gene delivery system is constructed by plasmid deoxyribonucleic acid (DNA) encoding glucagon-like peptide 1 (GLP-1) in ultrasound-induced microbubbles, toward treatment of T2D in macaque. The as designed UTMD afforded enhancement of cell membrane penetration and GLP-1 expression in macaque, which is characterized by ultrasound-guided biopsy to monitor the dynamic process of islet cells for 6 months. Also, improvement of pancreatic beta cell regeneration, and regulation of plasma glucose in macaque with T2D is achieved. The approach would serve as promising alternatives for the treatment of T2D.

Ectopic BAT mUCP-1 overexpression in SKM by delivering a BMP7/PRDM16/PGC-1a gene cocktail or single PRMD16 using non-viral UTMD gene therapy.

Here we present our progress in inducing an ectopic brown adipose tissue (BAT) phenotype in skeletal muscle (SKM) as a potential gene therapy for obesity and its comorbidities. We used ultrasound-targeted microbubble destruction (UTMD), a novel targeted, non-viral approach to gene therapy, to deliver genes in the BAT differentiation pathway into rodent SKM to engineer a thermogenic BAT phenotype with ectopic mUCP-1 overexpression. In parallel, we performed a second protocol using wild-type Ucp-1-null knockout mice to test whether the effects of the gene therapy are UCP-1 dependent. Our main findings were a robust cellular presence of mUCP-1 immunostaining (IHC), significantly higher expression levels of mUCP-1 measured by qRT-PCR, and highest temperature elevation measured by infrared thermography in the treated thigh, achieved in rats after delivering the UTMD-PRDM16/PGC-1a/BMP7/hyPB gene cocktail. Interestingly, the weight loss obtained in the treated rats with the triple gene delivery, never recovered the levels observed in the controls in spite of food intake recovery. Our results establish the feasibility of minimally invasive UTMD gene-based therapy administration in SKM, to induce overexpression of ectopic mUCP-1 after delivery of the thermogenic BAT gene program, and describe systemic effects of this intervention on food intake, weight loss, and thermogenesis.

Engineering brown fat into skeletal muscle using ultrasound-targeted microbubble destruction gene delivery in obese Zucker rats: Proof of concept design.

Ultrasound-targeted microbubble destruction (UTMD) is a novel means of tissue-specific gene delivery. This approach systemically infuses transgenes precoupled to gas-filled lipid microbubbles that are burst within the microvasculature of target tissues via an ultrasound signal resulting in release of DNA and transfection of neighboring cells within the tissue. Previous work has shown that adenovirus containing cDNA of UCP-1, injected into the epididymal fat pads in mice, induced localized fat depletion, improving glucose tolerance, and decreasing food intake in obese diabetic mice. Our group recently demonstrated that gene therapy by UTMD achieved beta cell regeneration in streptozotocin (STZ)-treated mice and baboons. We hypothesized that gene therapy with BMP7/PRDM16/PPARGC1A in skeletal muscle (SKM) of obese Zucker diabetic fatty (fa/fa) rats using UTMD technology would produce a brown adipose tissue (BAT) phenotype with UCP-1 overexpression. This study was designed as a proof of concept (POC) project. Obese Zucker rats were administered plasmid cDNA contructs encoding a gene cocktail with BMP7/PRDM16/PPARGC1A incorporated within microbubbles and intravenously delivered into their left thigh. Controls received UTMD with plasmids driving a DsRed reporter gene. An ultrasound transducer was directed to the thigh to disrupt the microbubbles within the microcirculation. Blood samples were drawn at baseline, and after treatment to measure glucose, insulin, and free fatty acids levels. SKM was harvested for immunohistochemistry (IHC). Our IHC results showed a reliable pattern of effective UTMD-based gene delivery in enhancing SKM overexpression of the UCP-1 gene. This clearly indicates that our plasmid DNA construct encoding the gene combination of PRDM16, PPARGC1A, and BMP7 reprogrammed adult SKM tissue into brown adipose cells in vivo. Our pilot established POC showing that the administration of the gene cocktail to SKM in this rat model of genetic obesity using UTMD gene therapy, engineered a BAT phenotype with UCP-1 over-expression. © 2017 IUBMB Life, 69(9):745-755, 2017.

Successful pharmaceutical-grade streptozotocin (STZ)-induced hyperglycemia in a conscious tethered baboon (Papio hamadryas) model.

BACKGROUND: Non-human primate (NHP) diabetic models using chemical ablation of ß-cells with STZ have been achieved by several research groups. Chemotherapeutic STZ could lead to serious adverse events including nephrotoxicity, hepatotoxicity, and mortality. METHODS: We implemented a comprehensive therapeutic strategy that included the tether system, permanent indwelling catheter implants, an aggressive hydration protocol, management for pain with IV nubain and anxiety with IV midazolam, moment-by-moment monitoring of glucose levels post-STZ administration, and continuous intravenous insulin therapy. RESULTS: A triphasic response in blood glucose after STZ administration was fully characterized. A dangerous hypoglycemic phase was also detected in all baboons. Other significant findings were hyperglycemia associated with low levels of plasma leptin, insulin and C-peptide concentrations, hyperglucagonemia, and elevated non-esterified fatty acids (NEFA) concentrations. CONCLUSIONS: We successfully induced frank diabetes by IV administering a single dose of pharmaceutical-grade STZ safely and without adverse events in conscious tethered baboons.

[Bone mineral density and its association with body composition and metabolic biomarkers of insulin-glucose axis, bone and adipose tissue in women]. / Densidad mineral ósea y su asociación con la composición corporal y biomarcadores metabólicos del eje insulino-glucosa, hueso y tejido adiposo en mujeres.

INTRODUCTION: There are few studies integrating the common causes of osteoporosis and obesity (disorders of body composition). A first step is to investigate correlations between their biological phenotypes to determine their common integrative physiology. OBJECTIVE: To correlate the variation of bone mineral density with phenotypes of body composition and biomarkers of bone physiology, insulin-glucose axis, and adipose tissue. METHODS: Cross-sectional study of 75 women (aged 18-45 years). MEASUREMENTS: Body mass index, waist, fat mass, lean mass (dual-energy X-ray absorptiometry), glucose, insulin, osteocalcin, leptin, tumor necrosis factor alpha. STATISTICAL ANALYSIS: multivariate general linear model, SPSS v.22, p<0.05. RESULTS: Age: 32.08±7.33. Bone mineral content multivariate general linear model 1 with two phenotypes excluded (glucose, insulin): osteocalcin (ß=-0.228, p=0.011), lean mass (ß=0.606, p=0.001) and fat mass (ß=1.237, p=0.001) in 62.0%. The bone mineral density multivariate general linear model 2 with three phenotypes excluded (body mass index, glucose, tumor necrosis factor alpha): insulin (ß=0.250, p=0.024), osteocalcin (ß=-0.362, p=0.001), lean mass (ß=0.512, p=0.001) and fat mass (ß=0.701, p=0.001) in 46.3%. CONCLUSIONS: Results show that body composition with an increased lean mass is beneficial to bone. This study reaffirms the importance of performing regular exercise to prevent muscle loss.

Body composition and cardiometabolic disease risk factors in captive baboons (Papio hamadryas sp.): sexual dimorphism.

Baboons (Papio hamadryas sp.) exhibit significant sexual dimorphism in body size. Sexual dimorphism is also exhibited in a number of circulating factors associated with risk of cardiometabolic disease. We investigated whether sexual dimorphism in body size and composition underlie these differences. We examined data from 28 male and 24 female outdoor group-housed young adult baboons enrolled in a longitudinal observational study of cardiometabolic disease risk factors. Animals were sedated with ketamine HCl (10 mg/kg) before undergoing venous blood draws, basic body measurements, and dual-energy X-ray absorptiometry body composition scans. Percentage glycated hemoglobin A1c (%HbA1c ) was measured in whole blood. Serum samples were analyzed for glucose, insulin, C-peptide, high-density lipoprotein, and triglyceride concentrations. Males were heavier and had greater body length and lean tissue mass than females. Females had a greater body fat percentage relative to males (10.8 ± 6.4 vs. 6.9 ± 4.0, P = 0.01). Although C-peptide, fasting glucose, and %HbA1c did not differ between the sexes, females had greater fasting insulin and triglyceride compared to their male counterparts. Insulin and percentage body fat were significantly correlated in males (r = 0.61, P = 0.001) and to a lesser extent in females (r = 0.43, P = 0.04). Overall, relations between adiposity and fasting insulin and fasting triglyceride were stronger in males. After accounting for differences in percentage body fat, fasting insulin and triglyceride were no longer statistically different between males and females. Despite stronger correlations between relative adiposity and insulin and triglyceride in males, the higher fasting insulin and triglyceride of female baboons may be underlain by their greater relative body fat masses.

Metabolic response to high-carbohydrate and low-carbohydrate meals in a nonhuman primate model.

We established a model of chronic portal vein catheterization in an awake nonhuman primate to provide a comprehensive evaluation of the metabolic response to low-carbohydrate/high-fat (LCHF; 20% carbohydrate and 65% fat) and high-carbohydrate/low-fat (HCLF; 65% carbohydrate and 20% fat) meal ingestion. Each meal was given 1 wk apart to five young adult (7.8 ± 1.3 yr old) male baboons. A [U-¹³C]glucose tracer was added to the meal, and a [6,6-²H2]glucose tracer was infused systemically to assess glucose kinetics. Plasma areas under the curve (AUCs) of glucose, insulin, and C-peptide in the femoral artery and of glucose and insulin in the portal vein were higher (P ≤ 0.05) after ingestion of the HCLF compared with the LCHF meal. Compared with the LCHF meal, the rate of appearance of ingested glucose into the portal vein and the systemic circulation was greater after the HCLF meal (P < 0.05). Endogenous glucose production decreased by ∼40% after ingestion of the HCLF meal but was not affected by the LCHF meal (P < 0.05). Portal vein blood flow increased (P < 0.001) to a similar extent after consumption of either meal. In conclusion, a LCHF diet causes minimal changes in the rate of glucose appearance in both portal and systemic circulations, does not affect the rate of endogenous glucose production, and causes minimal stimulation of C-peptide and insulin. These observations demonstrate that LCHF diets cause minimal perturbations in glucose homeostasis and pancreatic ß-cell activity.

Lessons learned from a peer-supported diabetes education program in two dissimilar Mayan communities.

Background: A steady rise in type 2 diabetes (T2D) in Mexico over the last 30 years has led to 11.5 million Mexicans being affected by this condition. There is an urgent need to develop interventions to prevent complications of T2D. Diabetes self-management education is the cornerstone of promoting self-care. Among all educational strategies, peer support has shown to be an effective method to encourage ongoing self-management. However, customization of interventions for distinct communities is imperative, as failure to do so can hinder the intervention's effectiveness. Methods: We implemented a two-year prospective randomized controlled community-based trial in Conkal, a Mayan community from Yucatan, Mexico. The intervention consisted of receiving either a culturally sensitive peer support on top of a diabetes self-management education group (PLG); or a diabetes self-management education group only (EOG; control group). The primary outcome was changes in glycated hemoglobin, while secondary outcomes encompassed changes in systolic and diastolic blood pressure, body mass index, and diabetes self-care practices. Data collection was performed at baseline and every four months during the study period. Discussion: Our experiences have highlighted the significance of peer-leader support in cultivating diabetes self-care skills, particularly within smaller, underserved communities characterized by strong social and cultural ties. However, when applied in larger or suburban settings, selecting peer leaders should be meticulous, considering sectorization within specific neighborhoods to foster a sense of belonging and familiarity among natural community clusters. In larger settlemnts, factors such as transportation challenges, time limitations, caregiving obligations, limited venue access, and changes in session locations can drive program discontinuation. Additionally, individuals with lower educational attainment are more susceptible to abandonment. Notably, those with lower education, uncontrolled diabetes, and extended diabetes duration exhibit a greater potential for improving glycemic control than their counterparts. Clinical registration: https://www.isrctn.com/ISRCTN96897082.

Selective cannabinoid-1 receptor blockade benefits fatty acid and triglyceride metabolism significantly in weight-stable nonhuman primates.

The goal of this study was to determine whether administration of the CB1 cannabinoid receptor antagonist rimonabant would alter fatty acid flux in nonhuman primates. Five adult baboons (Papio Sp) aged 12.1 ± 4.7 yr (body weight: 31.9 ± 2.1 kg) underwent repeated metabolic tests to determine fatty acid and TG flux before and after 7 wk of treatment with rimonabant (15 mg/day). Animals were fed ad libitum diets, and stable isotopes were administered via diet (d31-tripalmitin) and intravenously (¹³C4-palmitate, ¹³C1-acetate). Plasma was collected in the fed and fasted states, and blood lipids were analyzed by GC-MS. DEXA was used to assess body composition and a hyperinsulinemic euglycemic clamp used to assess insulin-mediated glucose disposal. During the study, no changes were observed in food intake, body weight, plasma, and tissue endocannabinoid concentrations or the quantity of liver-TG fatty acids originating from de novo lipogenesis (19 ± 6 vs. 16 ± 5%, for pre- and posttreatment, respectively, P = 0.39). However, waist circumference was significantly reduced 4% in the treated animals (P < 0.04), glucose disposal increased 30% (P = 0.03), and FFA turnover increased 37% (P = 0.02). The faster FFA flux was consistent with a 43% reduction in these fatty acids used for TRL-TG synthesis (40 ± 3 vs. 23 ± 4%, P = 0.02) and a twofold increase in TRL-TG turnover (1.5 ± 0.9 vs. 3.1 ± 1.4 µmol·kg⁻¹·h⁻¹, P = 0.03). These data support the potential for a strong effect of CB1 receptor antagonism at the level of adipose tissue, resulting in improvements in fasting turnover of fatty acids at the whole body level, central adipose storage, and significant improvements in glucose homeostasis.

Protocol for the measurement of fatty acid and glycerol turnover in vivo in baboons.

Recognition of the strength of nonhuman primate models in investigating metabolic disorders has resulted in an expanded need for in vivo research techniques. We studied adipose metabolism in 10 baboons (13.0 ± 4.2 years old, 29.5 ± 5.5 kg). Part 1 evaluated the effect of different sedatives on the rate of appearance of plasma free fatty acids (RaFFA), assessed using ¹³C4-labeled palmitate infusion (7 µmol/kg/min). Animals, were studied with no sedation, with complete isoflurane sedation, and with minimal midazolam infusion (0.04 mg/kg/h), with the last scheme allowing for the most consistent values and animals that were visually more calm. In Part 2, RaFFA and RaGlycerol (D5-glycerol, 5 mg/kg lean body mass/h) were measured. From midnight to 0300, flux fell and came to a steady state between 0500 and 0700 h (RaFFA, 39.4 ± 29.8 µmol/kg fat mass/min; and RaGlycerol, 26.9 ± 7.3 µmol/kg/min). The RaFFA-to-RaGlycerol ratio was 1.5 ± 0.8 (49% reesterification). The decline in turnover throughout the night reflects natural circadian processes and was mirrored by reductions in FFA and glycerol to 0.62 and ± 0.14 and 0.16 and ± 0.03 mmol/l, respectively. The concurrent changes in both FFA and glycerol kinetics indicate physiologic validity of the method. These techniques will support needed research to determine mechanisms by which treatments act upon the adipocyte in vivo.

Replication of Integrative Data Analysis for Adipose Tissue Dysfunction, Low-Grade Inflammation, Postprandial Responses and OMICs Signatures in Symptom-Free Adults.

We previously reported preliminary characterization of adipose tissue (AT) dysfunction through the adiponectin/leptin ratio (ALR) and fasting/postprandial (F/P) gene expression in subcutaneous (SQ) adipose tissue (AT) biopsies obtained from participants in the GEMM study, a precision medicine research project. Here we present integrative data replication of previous findings from an increased number of GEMM symptom-free (SF) adults (N = 124) to improve characterization of early biomarkers for cardiovascular (CV)/immunometabolic risk in SF adults with AT dysfunction. We achieved this goal by taking advantage of the rich set of GEMM F/P 5 h time course data and three tissue samples collected at the same time and frequency on each adult participant (F/P blood, biopsies of SQAT and skeletal muscle (SKM)). We classified them with the presence/absence of AT dysfunction: low (<1) or high (>1) ALR. We also examined the presence of metabolically healthy (MH)/unhealthy (MUH) individuals through low-grade chronic subclinical inflammation (high sensitivity C-reactive protein (hsCRP)), whole body insulin sensitivity (Matsuda Index) and Metabolic Syndrome criteria in people with/without AT dysfunction. Molecular data directly measured from three tissues in a subset of participants allowed fine-scale multi-OMIC profiling of individual postprandial responses (RNA-seq in SKM and SQAT, miRNA from plasma exosomes and shotgun lipidomics in blood). Dynamic postprandial immunometabolic molecular endophenotypes were obtained to move towards a personalized, patient-defined medicine. This study offers an example of integrative translational research, which applies bench-to-bedside research to clinical medicine. Our F/P study design has the potential to characterize CV/immunometabolic early risk detection in support of precision medicine and discovery in SF individuals.

Eight week exposure to a high sugar high fat diet results in adiposity gain and alterations in metabolic biomarkers in baboons (Papio hamadryas sp.).

BACKGROUND: Baboons (Papio hamadryas Sp.) develop features of the cardiometabolic syndrome and represent a clinically-relevant animal model in which to study the aetiology of the disorder. To further evaluate the baboon as a model for the study of the cardiometabolic syndrome, we developed a high sugar high fat diet and hypothesized that it could be used to induce adiposity gain and affect associated circulating biomarkers. METHODS: We developed a diet enriched with monosaccharides and saturated fatty acids that was composed of solid and liquid energy sources. We provided a group of baboons (n = 9) ad libitum access to this diet for 8 weeks. Concurrently, a control group (n = 6) was maintained with ad libitum access to a low sugar low fat baseline diet and normal water for 8 weeks. Body composition was determined by dual-energy X-ray absorptiometry and circulating metabolic biomarkers were measured using standard methodology before and after the 8 week study period. RESULTS: Neither body composition nor circulating biomarkers changed in the control group. Following the 8 weeks, the intervention group had a significant increase in fat mass (1.71 ± 0.98 vs. 3.23 ± 1.70 kg, p = 0.004), triglyceride (55 ± 13 vs. 109 ± 67 mg/dL, p = 0.006,), and leptin (1.19 ± 1.40 vs. 3.29 ± 2.32 ng/mL, p = 0.001) and a decline in adiponectin concentrations (33530 ± 9744 vs. 23330 ± 7863 ng/mL, p = 0.002). Percentage haemoglobin A1C (4.0 ± 0.3 vs. 6.0 ± 1.4, p = 0.002) also increased in the intervention group. CONCLUSIONS: Our findings indicate that when exposed to a high sugar high fat diet, young adult male baboons develop increased body fat and triglyceride concentrations, altered adipokine concentrations, and evidence of altered glucose metabolism. Our findings are in keeping with observations in humans and further demonstrate the potential utility of this highly clinically-relevant animal model for studying diet-induced metabolic dysregulation.

The COVID-19 Pandemic during the Time of the Diabetes Pandemic: Likely Fraternal Twins?

An altered immune response to pathogens has been suggested to explain increased susceptibility to infectious diseases in patients with diabetes. Recent evidence has documented several immunometabolic pathways in patients with diabetes directly related to the COVID-19 infection. This also seems to be the case for prediabetic subjects with proinflammatory insulin resistance syndrome accompanied with prothrombotic hyperinsulinemic and dysglycemic states. Patients with frank hyperglycemia, dysglycemia and/or hyperinsulinemia develop systemic immunometabolic inflammation with higher levels of circulating cytokines. This deleterious scenario has been proposed as the underlying mechanism enhancing a cytokine storm-like hyperinflammatory state in diabetics infected with severe COVID-19 triggering multi-organ failure. Compared with moderately affected COVID-19 patients, diabetes was found to be highly prevalent among severely affected patients suggesting that this non-communicable disease should be considered as a risk factor for adverse outcomes. The COVID-19 pandemic mirrors with the diabetes pandemic in many pathobiological aspects. Our interest is to emphasize the ties between the immunoinflammatory mechanisms that underlie the morbidity and lethality when COVID-19 meets diabetes. This review brings attention to two pathologies of highly complex, multifactorial, developmental and environmentally dependent manifestations of critical importance to human survival. Extreme caution should be taken with diabetics with suspected symptoms of COVID-19 infection.

Research methodology for in vivo measurements of resting energy expenditure, daily body temperature, metabolic heat and non-viral tissue-specific gene therapy in baboons.

A large number of studies have shown that the baboon is one of the most commonly used non-human primate (NHP) research model for the study of immunometabolic complex traits such as type 2 diabetes (T2D), insulin resistance (IR), adipose tissue dysfunction (ATD), dyslipidemia, obesity (OB) and cardiovascular disease (CVD). This paper reports on innovative technologies and advanced research strategies for energetics and translational medicine with this NHP model. This includes the following: measuring resting energy expenditure (REE) with the mobile indirect calorimeter Breezing®; monitoring daily body temperature using subcutaneously implanted data loggers; quantifying metabolic heat with veterinary infrared thermography (IRT) imaging, and non-viral non-invasive, tissue-specific ultrasound-targeted microbubble destruction (UTMD) gene-based therapy. These methods are of broad utility; for example, they may facilitate the engineering of ectopic overexpression of brown adipose tissue (BAT) mUCP-1 via UTMD-gene therapy into baboon SKM to achieve weight loss, hypophagia and immunometabolic improvement. These methods will be valuable to basic and translational research, and human clinical trials, in the areas of metabolism, cardiovascular health, and immunometabolic and infectious diseases.

Towards precision medicine: defining and characterizing adipose tissue dysfunction to identify early immunometabolic risk in symptom-free adults from the GEMM family study.

Interactions between macrophages and adipocytes are early molecular factors influencing adipose tissue (AT) dysfunction, resulting in high leptin, low adiponectin circulating levels and low-grade metaflammation, leading to insulin resistance (IR) with increased cardiovascular risk. We report the characterization of AT dysfunction through measurements of the adiponectin/leptin ratio (ALR), the adipo-insulin resistance index (Adipo-IRi), fasting/postprandial (F/P) immunometabolic phenotyping and direct F/P differential gene expression in AT biopsies obtained from symptom-free adults from the GEMM family study. AT dysfunction was evaluated through associations of the ALR with F/P insulin-glucose axis, lipid-lipoprotein metabolism, and inflammatory markers. A relevant pattern of negative associations between decreased ALR and markers of systemic low-grade metaflammation, HOMA, and postprandial cardiovascular risk hyperinsulinemic, triglyceride and GLP-1 curves was found. We also analysed their plasma non-coding microRNAs and shotgun lipidomics profiles finding trends that may reflect a pattern of adipose tissue dysfunction in the fed and fasted state. Direct gene differential expression data showed initial patterns of AT molecular signatures of key immunometabolic genes involved in AT expansion, angiogenic remodelling and immune cell migration. These data reinforce the central, early role of AT dysfunction at the molecular and systemic level in the pathogenesis of IR and immunometabolic disorders.

Predictive models of insulin resistance derived from simple morphometric and biochemical indices related to obesity and the metabolic syndrome in baboons.

BACKGROUND: Non-human primates are valuable models for the study of insulin resistance and human obesity. In baboons, insulin sensitivity levels can be evaluated directly with the euglycemic clamp and is highly predicted by adiposity, metabolic markers of obesity and impaired glucose metabolism (i.e. percent body fat by DXA and HbA1c). However, a simple method to screen and identify obese insulin resistant baboons for inclusion in interventional studies is not available. METHODS: We studied a population of twenty baboons with the euglycemic clamp technique to characterize a population of obese nondiabetic, insulin resistant baboons, and used a multivariate linear regression analysis (adjusted for gender) to test different predictive models of insulin sensitivity (insulin-stimulated glucose uptake = Rd) using abdominal circumference and fasting plasma insulin. Alternatively, we tested in a separate baboon population (n = 159), a simpler model based on body weight and fasting plasma glucose to predict the whole-body insulin sensitivity (Rd/SSPI) derived from the clamp. RESULTS: In the first model, abdominal circumference explained 59% of total insulin mediated glucose uptake (Rd). A second model, which included fasting plasma insulin (log transformed) and abdominal circumference, explained 64% of Rd. Finally, the model using body weight and fasting plasma glucose explained 51% of Rd/SSPI. Interestingly, we found that percent body fat was directly correlated with the adipocyte insulin resistance index (r = 0.755, p < 0.0001). CONCLUSION: In baboons, simple morphometric measurements of adiposity/obesity, (i.e. abdominal circumference), plus baseline markers of glucose/lipid metabolism, (i.e. fasting plasma glucose and insulin) provide a feasible method to screen and identify overweight/obese insulin resistant baboons for inclusion in interventional studies aimed to study human obesity, insulin resistance and type 2 diabetes mellitus.

Exenatide regulates pancreatic islet integrity and insulin sensitivity in the nonhuman primate baboon Papio hamadryas.

The glucagon-like peptide-1 receptor agonist exenatide improves glycemic control by several and not completely understood mechanisms. Herein, we examined the effects of chronic intravenous exenatide infusion on insulin sensitivity, ß cell and α cell function and relative volumes, and islet cell apoptosis and replication in nondiabetic nonhuman primates (baboons). At baseline, baboons received a 2-step hyperglycemic clamp followed by an l-arginine bolus (HC/A). After HC/A, baboons underwent a partial pancreatectomy (tail removal) and received a continuous exenatide (n = 12) or saline (n = 12) infusion for 13 weeks. At the end of treatment, HC/A was repeated, and the remnant pancreas (head-body) was harvested. Insulin sensitivity increased dramatically after exenatide treatment and was accompanied by a decrease in insulin and C-peptide secretion, while the insulin secretion/insulin resistance (disposition) index increased by about 2-fold. ß, α, and δ cell relative volumes in exenatide-treated baboons were significantly increased compared with saline-treated controls, primarily as the result of increased islet cell replication. Features of cellular stress and secretory dysfunction were present in islets of saline-treated baboons and absent in islets of exenatide-treated baboons. In conclusion, chronic administration of exenatide exerts proliferative and cytoprotective effects on ß, α, and δ cells and produces a robust increase in insulin sensitivity in nonhuman primates.

Congenital Leptin Deficiency and Leptin Gene Missense Mutation Found in Two Colombian Sisters with Severe Obesity.

BACKGROUND: Congenital leptin deficiency is a recessive genetic disorder associated with severe early-onset obesity. It is caused by mutations in the leptin (LEP) gene, which encodes the protein product leptin. These mutations may cause nonsense-mediated mRNA decay, defective secretion or the phenomenon of biologically inactive leptin, but typically lead to an absence of circulating leptin, resulting in a rare type of monogenic extreme obesity with intense hyperphagia, and serious metabolic abnormalities. METHODS: We present two severely obese sisters from Colombia, members of the same lineal consanguinity. Their serum leptin was measured by MicroELISA. DNA sequencing was performed on MiSeq equipment (Illumina) of a next-generation sequencing (NGS) panel involving genes related to severe obesity, including LEP. RESULTS: Direct sequencing of the coding region of LEP gene in the sisters revealed a novel homozygous missense mutation in exon 3 [NM_002303.3], C350G>T [p.C117F]. Detailed information and clinical measurements of these sisters were also collected. Their serum leptin levels were undetectable despite their markedly elevated fat mass. CONCLUSIONS: The mutation of LEP, absence of detectable leptin, and the severe obesity found in these sisters provide the first evidence of monogenic leptin deficiency reported in the continents of North and South America.

[Transciptome among Mexicans: a large scale methodology to analyze the genetics expression profile of simultaneous samples in muscle, adipose tissue and lymphocytes obtained from the same individual]. / Transcriptoma en mexicanos: metodología para analizar el perfil de expresión genética de gran escala en muestras simultáneas de tejido muscular, adiposo y linfocitos obtenidas en un mismo individuo.

OBJECTIVE: We describe the methodology used to analyze multiple transcripts using microarray techniques in simultaneous biopsies of muscle, adipose tissue and lymphocytes obtained from the same individual as part of the standard protocol of the Genetics of Metabolic Diseases in Mexico: GEMM Family Study. METHODS: We recruited 4 healthy male subjects with BM1 20-41, who signed an informed consent letter. Subjects participated in a clinical examination that included anthropometric and body composition measurements, muscle biopsies (vastus lateralis) subcutaneous fat biopsies anda blood draw. All samples provided sufficient amplified RNA for microarray analysis. Total RNA was extracted from the biopsy samples and amplified for analysis. RESULTS: Of the 48,687 transcript targets queried, 39.4% were detectable in a least one of the studied tissues. Leptin was not detectable in lymphocytes, weakly expressed in muscle, but overexpressed and highly correlated with BMI in subcutaneous fat. Another example was GLUT4, which was detectable only in muscle and not correlated with BMI. Expression level concordance was 0.7 (p< 0.001) for the three tissues studied. CONCLUSIONS: We demonstrated the feasibility of carrying out simultaneous analysis of gene expression in multiple tissues, concordance of genetic expression in different tissues, and obtained confidence that this method corroborates the expected biological relationships among LEPand GLUT4. TheGEMM study will provide a broad and valuable overview on metabolic diseases, including obesity and type 2 diabetes.

Mesenteric visceral lipectomy using tissue liquefaction technology reverses insulin resistance and causes weight loss in baboons.

BACKGROUND: Visceral obesity is associated with diabetogenic and atherogenic abnormalities, including insulin resistance and increased risk for cardiometabolic diseases and mortality. Rodent lipectomy studies have demonstrated a causal link between visceral fat and insulin resistance, yet human omentectomy studies have failed to replicate this metabolic benefit, perhaps owing to the inability to target the mesentery. OBJECTIVES: We aimed to demonstrate that safe and effective removal of mesenteric fat could be achieved in obese insulin-resistant baboons using tissue liquefaction technology. SETTING: Southwest National Primate Research Center, San Antonio, Texas. METHODS: Tissue liquefaction technology has been developed to enable mesenteric visceral lipectomy (MVL) to be safely performed without disturbing the integrity of surrounding nerves and vessels in the mesentary. After an initial MVL optimization study (n = 3), we then performed MVL (n = 4) or sham surgery (n = 2) in a cohort of insulin-resistant baboons, and the metabolic phenotype was assessed via hyperinsulinemic-euglycemic clamps at baseline and 6 weeks later. RESULTS: MVL led to a 75% improvement in glucose disposal at 6-weeks follow-up (P = .01). Moreover, despite removing only an average of 430 g of mesenteric fat (~1% of total body mass), MVL led to a 14.4% reduction in total weight (P = .001). Thus, these data demonstrate that mesenteric fat can be safely targeted for removal by tissue liquefaction technology in a nonhuman primate, leading to substantial metabolic improvements, including reversal of insulin resistance and weight loss. CONCLUSIONS: These data provide the first demonstration of successful adipose tissue removal from the mesentery in a mammal. Importantly, we have demonstrated that when MVL is performed in obese, insulin-resistant baboons, insulin resistance is reversed, and significant weight loss occurs. Therefore, trials performing MVL in humans with abdominal obesity and related metabolic sequelae should be explored as a potential clinical tool to ameliorate insulin resistance and treat type 2 diabetes.