Extended survival versus accelerated rejection of nonhuman primate islet allografts: Effect of mesenchymal stem cell source and timing.

Mesenchymal stem cells (MSC) have been shown to be immunomodulatory, tissue regenerative, and graft promoting; however, several questions remain with regard to ideal MSC source and timing of administration. In this study, we utilized a rigorous preclinical model of allogeneic islet cell transplantation, incorporating reduced immune suppression and near to complete mismatch of major histocompatibility antigens between the diabetic cynomolgus monkey recipient and the islet donor, to evaluate both the graft promoting impact of MSC source, that is, derived from the islet recipient, the islet donor or an unrelated third party as well as the impact of timing. Co-transplant of MSC and islets on post-operative day 0, followed by additional IV MSC infusions in the first posttransplant month, resulted in prolongation of rejection free and overall islet survival and superior metabolic control for animals treated with recipient as compared to donor or third-party MSC. Immunological analyses demonstrated that infusion of MSC from either source did not prevent alloantibody formation to the islet or MSC donor; however, treatment with recipient MSC resulted in significant downregulation of memory T cells, decreased anti-donor T cell proliferation, and a trend toward increased Tregulatory:Tconventional ratios.

Transplantation of PEGylated islets enhances therapeutic efficacy in a diabetic nonhuman primate model.

Islet cell transplantation can lead to insulin independence, reduced hypoglycemia, and amelioration of diabetes complications in patients with type 1 diabetes. The systemic delivery of anti-inflammatory agents, while considered crucial to limit the early loss of islets associated with intrahepatic infusion, increases the burden of immunosuppression. In an effort to decrease the pharmaceutical load to the patient, we modified the pancreatic islet surface with long-chain poly(ethylene glycol) (PEG) to mitigate detrimental host-implant interactions. The effect of PEGylation on islet engraftment and long-term survival was examined in a robust nonhuman primate model via three paired transplants of dosages 4300, 8300, and 10 000 islet equivalents per kg body weight. A reduced immunosuppressive regimen of anti-thymocyte globulin induction plus tacrolimus in the first posttransplant month followed by maintenance with sirolimus monotherapy was employed. To limit transplant variability, two of the three pairs were closely MHC-matched recipients and received MHC-disparate PEGylated or untreated islets isolated from the same donors. Recipients of PEGylated islets exhibited significantly improved early c-peptide levels, reduced exogenous insulin requirements, and superior glycemic control, as compared to recipients of untreated islets. These results indicate that this simple islet modification procedure may improve islet engraftment and survival in the setting of reduced immunosuppression.

Operational immune tolerance towards transplanted allogeneic pancreatic islets in mice and a non-human primate.

AIMS/HYPOTHESIS: Patients with autoimmune type 1 diabetes transplanted with pancreatic islets to their liver experience significant improvement in quality of life through better control of blood sugar and enhanced awareness of hypoglycaemia. However, long-term survival and efficacy of the intrahepatic islet transplant are limited owing to liver-specific complications, such as immediate blood-mediated immune reaction, hypoxia, a highly enzymatic and inflammatory environment and locally elevated levels of drugs including immunosuppressive agents, all of which are injurious to islets. This has spurred a search for new islet transplant sites and for innovative ways to achieve long-term graft survival and efficacy without life-long systemic immunosuppression and its complications. METHODS: We used our previously established approach of islet transplant in the anterior chamber of the eye in allogeneic recipient mouse models and a baboon model of diabetes, which were treated transiently with anti-CD154/CD40L blocking antibody in the peri-transplant period. Survival of the intraocular islet allografts was assessed by direct visualisation in the eye and metabolic variables (blood glucose and C-peptide measurements). We evaluated longitudinally the cytokine profile in the local microenvironment of the intraocular islet allografts, represented in aqueous humour, under conditions of immune rejection vs tolerance. We also evaluated the recall response in the periphery of the baboon recipient using delayed-type hypersensitivity (DTH) assay, and in mice after repeat transplant in the kidney following initial transplant with allogeneic islets in the eye or kidney. RESULTS: Results in mice showed >300 days immunosuppression-free survival of allogeneic islets transplanted in the eye or kidney. Notably, >70% of tolerant mice, initially transplanted in the eye, exhibited >400 days of graft survival after re-transplant in the kidney without immunosuppression compared with ~30% in mice that were initially transplanted in the kidney. Cytokine and DTH data provided evidence of T helper 2-driven local and peripheral immune regulatory mechanisms in support of operational immune tolerance towards the islet allografts in both models. CONCLUSIONS/INTERPRETATION: We are currently evaluating the safety and efficacy of intraocular islet transplantation in a phase 1 clinical trial. In this study, we demonstrate immunosuppression-free long-term survival of intraocular islet allografts in mice and in a baboon using transient peri-transplant immune intervention. These results highlight the potential for inducing islet transplant immune tolerance through the intraocular route. Therefore, the current findings are conceptually significant and may impact markedly on clinical islet transplantation in the treatment of diabetes.

Microencapsulated adult porcine islets transplanted intraperitoneally in streptozotocin-diabetic non-human primates.

BACKGROUND: Xenogeneic donors would provide an unlimited source of islets for the treatment of type 1 diabetes (T1D). The goal of this study was to assess the function of microencapsulated adult porcine islets (APIs) transplanted ip in streptozotocin (STZ)-diabetic non-human primates (NHPs) given targeted immunosuppression. METHODS: APIs were encapsulated in: (a) single barium-gelled alginate capsules or (b) double alginate capsules with an inner, islet-containing compartment and a durable, biocompatible outer alginate layer. Immunosuppressed, streptozotocin-diabetic NHPs were transplanted ip with encapsulated APIs, and graft function was monitored by measuring blood glucose, %HbA1c, and porcine C-peptide. At graft failure, explanted capsules were assessed for biocompatibility and durability plus islet viability and functionality. Host immune responses were evaluated by phenotyping peritoneal cell populations, quantitation of peritoneal cytokines and chemokines, and measurement of anti-porcine IgG and IgM plus anti-Gal IgG. RESULTS: NHP recipients had reduced hyperglycemia, decreased exogenous insulin requirements, and lower percent hemoglobin A1c (%HbA1c) levels. Porcine C-peptide was detected in plasma of all recipients, but these levels diminished with time. However, relatively high levels of porcine C-peptide were detected locally in the peritoneal graft site of some recipients at sacrifice. IV glucose tolerance tests demonstrated metabolic function, but the grafts eventually failed in all diabetic NHPs regardless of the type of encapsulation or the host immunosuppression regimen. Explanted microcapsules were intact, "clean," and free-floating without evidence of fibrosis at graft failure, and some reversed diabetes when re-implanted ip in diabetic immunoincompetent mice. Histology of explanted capsules showed scant evidence of a host cellular response, and viable islets could be found. Flow cytometric analyses of peritoneal cells and peripheral blood showed similarly minimal evidence of a host immune response. Preformed anti-porcine IgG and IgM antibodies were present in recipient plasma, but these levels did not rise post-transplant. Peritoneal graft site cytokine or chemokine levels were equivalent to normal controls, with the exception of minimal elevation observed for IL-6 or IL-1ß, GRO-α, I-309, IP-10, and MCP-1. However, we found central necrosis in many of the encapsulated islets after graft failure, and explanted islets expressed endogenous markers of hypoxia (HIF-1α, osteopontin, and GLUT-1), suggesting a role for non-immunologic factors, likely hypoxia, in graft failure. CONCLUSIONS: With donor xenoislet microencapsulation and host immunosuppression, APIs corrected hyperglycemia after ip transplantation in STZ-diabetic NHPs in the short term. The islet xenografts lost efficacy gradually, but at graft failure, some viable islets remained, substantial porcine C-peptide was detected in the peritoneal graft site, and there was very little evidence of a host immune response. We postulate that chronic effects of non-immunologic factors, such as in vivo hypoxic and hyperglycemic conditions, damaged the encapsulated islet xenografts. To achieve long-term function, new approaches must be developed to prevent this damage, for example, by increasing the oxygen supply to microencapsulated islets in the ip space.

Isolation of Pancreatic Islets from Nonhuman Primates.

Nonhuman primates (NHP) constitute a highly relevant pre-clinical animal model to develop strategies for beta cell replacement. The close phylogenetic and immunologic relationship between NHP and humans results in cross-reactivity of various biological agents with NHP cells, as well as a very similar cytoarchitecture between islets from human and NHP that is strikingly different from that observed in rodent islets. The composition and location of endocrine cells in human or NHP islets, randomly distributed and associated with blood vessels, have functional consequences and a predisposition for paracrine interactions. Furthermore, translation of approaches that proved successful in rodent models to the clinic has been limited. Consequently, data collected from NHP studies can form the basis for an IND submission to the FDA. This chapter describes in detail the key aspects for isolation of islets from NHP, from organ procurement up to assessment of islet function, comparing and emphasizing the similarities between isolation procedures for human and NHP islets.

ATP-gated P2X3 receptors constitute a positive autocrine signal for insulin release in the human pancreatic beta cell.

Extracellular ATP has been proposed as a paracrine signal in rodent islets, but it is unclear what role ATP plays in human islets. We now show the presence of an ATP signaling pathway that enhances the human beta cell's sensitivity and responsiveness to glucose fluctuations. By using in situ hybridization, RT-PCR, immunohistochemistry, and Western blotting as well as recordings of cytoplasmic-free Ca(2+) concentration, [Ca(2+)](i), and hormone release in vitro, we show that human beta cells express ionotropic ATP receptors of the P2X(3) type and that activation of these receptors by ATP coreleased with insulin amplifies glucose-induced insulin secretion. Released ATP activates P2X(3) receptors in the beta-cell plasma membrane, resulting in increased [Ca(2+)](i) and enhanced insulin secretion. Therefore, in human islets, released ATP forms a positive autocrine feedback loop that sensitizes the beta cell's secretory machinery. This may explain how the human pancreatic beta cell can respond so effectively to relatively modest changes in glucose concentration under physiological conditions in vivo.

The anti-CD40L monoclonal antibody AT-1501 promotes islet and kidney allograft survival and function in nonhuman primates.

Prior studies of anti-CD40 ligand (CD40L)-based immunosuppression demonstrated effective prevention of islet and kidney allograft rejection in nonhuman primate models; however, clinical development was halted because of thromboembolic complications. An anti-CD40L-specific monoclonal antibody, AT-1501 (Tegoprubart), was engineered to minimize risk of thromboembolic complications by reducing binding to Fcγ receptors expressed on platelets while preserving binding to CD40L. AT-1501 was tested in both a cynomolgus macaque model of intrahepatic islet allotransplantation and a rhesus macaque model of kidney allotransplantation. AT-1501 monotherapy led to long-term graft survival in both islet and kidney transplant models, confirming its immunosuppressive potential. Furthermore, AT-1501-based regimens after islet transplant resulted in higher C-peptide, greater appetite leading to weight gain, and reduced occurrence of cytomegalovirus reactivation compared with conventional immunosuppression. These data support AT-1501 as a safe and effective agent to promote both islet and kidney allograft survival and function in nonhuman primate models, warranting further testing in clinical trials.

Performance of islets of Langerhans conformally coated via an emulsion cross-linking method in diabetic rodents and nonhuman primates.

Polyethylene glycol (PEG)-based conformal coating (CC) encapsulation of transplanted islets is a promising ß cell replacement therapy for the treatment of type 1 diabetes without chronic immunosuppression because it minimizes capsule thickness, graft volume, and insulin secretion delay. However, we show here that our original CC method, the direct method, requiring exposure of islets to low pH levels and inclusion of viscosity enhancers during coating, severely affected the viability, scalability, and biocompatibility of CC islets in nonhuman primate preclinical models of type 1 diabetes. We therefore developed and validated in vitro and in vivo, in several small- and large-animal models of type 1 diabetes, an augmented CC method-emulsion method-that achieves hydrogel CCs around islets at physiological pH for improved cytocompatibility, with PEG hydrogels for increased biocompatibility and with fivefold increase in encapsulation throughput for enhanced scalability.

Implantable niche with local immunosuppression for islet allotransplantation achieves type 1 diabetes reversal in rats.

Pancreatic islet transplantation efficacy for type 1 diabetes (T1D) management is limited by hypoxia-related graft attrition and need for systemic immunosuppression. To overcome these challenges, we developed the Neovascularized Implantable Cell Homing and Encapsulation (NICHE) device, which integrates direct vascularization for facile mass transfer and localized immunosuppressant delivery for islet rejection prophylaxis. Here, we investigated NICHE efficacy for allogeneic islet transplantation and long-term diabetes reversal in an immunocompetent, male rat model. We demonstrated that allogeneic islets transplanted within pre-vascularized NICHE were engrafted, revascularized, and functional, reverting diabetes in rats for over 150 days. Notably, we confirmed that localized immunosuppression prevented islet rejection without inducing toxicity or systemic immunosuppression. Moreover, for translatability efforts, we showed NICHE biocompatibility and feasibility of deployment as well as short-term allogeneic islet engraftment in an MHC-mismatched nonhuman primate model. In sum, the NICHE holds promise as a viable approach for safe and effective islet transplantation and long-term T1D management.

Steroid-Free Immune Suppression Impairs Glycemic Control in a Healthy Cynomolgus Monkey.

The need for chronic immune suppression (IS) is one of the hurdles precluding widespread use of islet cell transplantation to restore glycemic control in patients with type 1 diabetes. We report the case of a healthy nonhuman primate (NHP) treated on and off for over 2.5 years with steroid-free IS, consisting of daclizumab induction and maintenance therapy with rapamycin and low dose tacrolimus. Treatment for 1 year resulted in a striking destabilization of glycemic control, with concomitant decreases in fasting c-peptide and insulin levels. Although these changes gradually reversed during a wash out period of 7 months, retreatment with the same therapy led to accelerated deterioration in glycemic control. Intravenous glucose tolerance and percentage of glycosylated hemoglobin testing further supported a dramatic effect on metabolic control. IS also led to decreases in weight during treatment. Histological evaluation of the pancreas revealed islet hyperplasia, with varying sizes and endocrine cell ratios that differed from normal islet composition, and parenchymal infiltration with adipose tissue. These deleterious effects of IS on glucose control and endocrine components in the native pancreas of a healthy NHP suggest that IS agents commonly utilized for islet transplantation may contribute to failure in islet allograft function in long-term transplant patients.

Automated, high-throughput assays for evaluation of human pancreatic islet function.

An important challenge in pancreatic islet transplantation in association with type 1 diabetes is to define automatic high-throughput assays for evaluation of human islet function. The physiological techniques presently used are amenable to small-scale experimental samples and produce descriptive results. The postgenomic era provides an opportunity to analyze biological processes on a larger scale, but the transition to high-throughput technologies is still a challenge. As a first step to implement high-throughput assays for the study of human islet function, we have developed two methodologies: multiple automated perifusion to determine islet hormone secretion and high-throughput kinetic imaging to examine islet cellular responses. Both technologies use fully automated devices that allow performing simultaneous experiments on multiple islet preparations. Our results illustrate that these technologies can be applied to study the functional status and explore the pharmacological profiles of islet cells. These methodologies will enable functional characterization of human islet preparations before transplantation and thereby provide the basis for the establishment of predictive tests for beta-cell potency.

Paracrine Interactions within the Pancreatic Islet Determine the Glycemic Set Point.

Every animal species has a signature blood glucose level or glycemic set point. These set points are different, and the normal glycemic levels (normoglycemia) of one species would be life threatening for other species. Mouse normoglycemia can be considered diabetic for humans. The biological determinants of the glycemic set point remain unclear. Here we show that the pancreatic islet imposes its glycemic set point on the organism, making it the bona fide glucostat in the body. Moreover, and in contrast to rodent islets, glucagon input from the alpha cell to the insulin-secreting beta cell is necessary to fine-tune the distinctive human set point. These findings affect transplantation and regenerative approaches to treat diabetes because restoring normoglycemia may require more than replacing only the beta cells. Furthermore, therapeutic strategies using glucagon receptor antagonists as hypoglycemic agents need to be reassessed, as they may reset the overall glucostat in the organism.

CD40-CD40 ligand interaction activates proinflammatory pathways in pancreatic islets.

Pancreatic islet transplantation is becoming an alternative to insulin therapy in patients suffering from brittle type 1 diabetes. A major obstacle to the procedure is the early graft loss caused by nonspecific inflammation at the site of implantation. We recently discovered that CD40, a member of tumor necrosis factor (TNF) receptor family, is expressed in pancreatic beta-cells. CD40 expression in nonhematopoietic cells is generally associated with inflammation. Therefore, we investigated the potential proinflammatory role of CD40 in human and nonhuman primate islets. Islet beta-cells responded to CD40L interaction by secreting interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1, and macrophage inflammatory protein (MIP)-1beta, the latter a chemokine first reported to be produced by islets. Induction of IL-8 and MIP-1beta was confirmed at the transcriptional level by quantitative RT-PCR. MIP-1beta expression in beta-cells was verified by double-immunofluorescence staining. CD40-CD40L interaction activates extracellular signal-regulated kinase 1/2 and nuclear factor-kappaB pathways in insulinoma NIT-1 cells, and inhibitors of either pathway suppress cytokine/chemokine production in islets. Moreover, ligation of CD40 receptor upregulates intercellular adhesion molecule-1, associated with inflammation, at both transcriptional and translational levels. Our results in vitro indicate that the CD40 receptor expressed by beta-cells could be activated in vivo, inducing proinflammatory responses contributing to early islet graft loss after transplantation.

Sequence-specific analysis of microchimerism by real-time quantitative polymerase chain reaction in same-sex nonhuman primates after islet and bone marrow transplantation.

BACKGROUND: Accurate and sensitive detection of microchimerism in nonhuman primates (NHPs) after hematopoietic cell transplantation is essential for monitoring cell engraftment, for evaluating the success of transplant protocols, and for expanding the utility of NHP in transplantation studies. Because limited sequences are available for NHP major histocompatibility complex polymorphic loci, methods that can accurately determine low levels of donor cells in recipients with same-sex bone marrow transplantation are essential. METHODS: Thirty-seven pairs of primers, 16 from monkey and 21 from human, were screened with cynomolgus DNA samples. Real-time quantitative polymerase chain reaction was developed for accurately determining low levels of donor-specific DNA in the peripheral blood of islet/bone marrow transplant recipients of same sex cynomolgus monkeys. RESULTS: A total of six sets of primer and Taqman(R) probe combinations were included in this study, which are the most informative primer and probe sets ever reported for cynomolgus monkeys. Three pairs of primers were chosen from exon 2 of the Macaca DRB1 gene and another three pairs were chosen from human HLA DRB1 and DRB3 loci. Three of the six primer-probe sets were also found to work well for baboon (Papio hamadryas) and rhesus monkeys (Macaca mulatta). Sensitivity of the assay ranged from 0.03% to 0.1%, depending on the primer-probe set and donor-recipient pair. The methods are reproducible with relatively low standard error and coefficient of variation. CONCLUSIONS: This method is an informative, practical and sensitive method for the determination of donor-specific cells in the peripheral blood of NHP recipients of bone marrow transplant.

Interference with tissue factor prolongs intrahepatic islet allograft survival in a nonhuman primate marginal mass model.

BACKGROUND: Tissue factor (TF) expression on islets can result in an instant blood-mediated inflammatory reaction (IBMIR) that contributes to early islet loss. We tested whether peritransplant protection of islets from IBMIR with a monoclonal anti-TF antibody (CNTO859) would enhance engraftment in our nonhuman primate marginal mass model. METHODS: Each of six pairs of cynomolgus monkeys (CM) with streptozotocin-induced diabetes was closely matched for metabolic control and was transplanted with 5,000 IEQ/kg allogeneic, ABO-compatible islets from the same donor under the cover of steroid-free immunosuppression. For each pair, experimental animals received islets cultured with 20 microg/mL anti-TF and were dosed with 6 mg/kg anti-TF intravenously, 10-25 min before islet infusion; control monkeys received an equal number of islets from the same preparation cultured without anti-TF and no in vivo treatment. RESULTS: Early fasting C-peptide (CP) values were different between (P<0.01), but not within, pairs and correlated with in vitro functional capacity of islets as assessed by perifusion (r=0.60; P=0.022). Compared to their matched controls, experimental animals had decreased posttransplant markers of coagulation, higher fasting CP levels (1 month posttransplant and end of study) and prolonged graft function. CONCLUSIONS: These data suggest that pretreatment of islets and the recipient with anti-TF may limit the effects of IBMIR, thereby enhancing islet engraftment and survival.

Bioengineering the Endocrine Pancreas: Intraomental Islet Transplantation Within a Biologic Resorbable Scaffold.

Transplantation of pancreatic islets is a therapeutic option to preserve or restore ß-cell function. Our study was aimed at developing a clinically applicable protocol for extrahepatic transplantation of pancreatic islets. The potency of islets implanted onto the omentum, using an in situ-generated adherent, resorbable plasma-thrombin biologic scaffold, was evaluated in diabetic rat and nonhuman primate (NHP) models. Intraomental islet engraftment in the biologic scaffold was confirmed by achievement of improved metabolic function and preservation of islet cytoarchitecture, with reconstitution of rich intrainsular vascular networks in both species. Long-term nonfasting normoglycemia and adequate glucose clearance (tolerance tests) were achieved in both intrahepatic and intraomental sites in rats. Intraomental graft recipients displayed lower levels of serum biomarkers of islet distress (e.g., acute serum insulin) and inflammation (e.g., leptin and α2-macroglobulin). Importantly, low-purity (30:70% endocrine:exocrine) syngeneic rat islet preparations displayed function equivalent to that of pure (>95% endocrine) preparations after intraomental biologic scaffold implantation. Moreover, the biologic scaffold sustained allogeneic islet engraftment in immunosuppressed recipients. Collectively, our feasibility/efficacy data, along with the simplicity of the procedure and the safety of the biologic scaffold components, represented sufficient preclinical testing to proceed to a pilot phase I/II clinical trial.

Hormone replacement therapy, insulin sensitivity, and abdominal obesity in postmenopausal women.

OBJECTIVE: The purpose of this study was to determine whether insulin sensitivity differs between postmenopausal women taking estradiol, women on estrogen plus progesterone hormone replacement therapy (HRT), and women not on HRT and whether differences are explained by the differences in total and/or abdominal adiposity and fat deposition in the muscle. RESEARCH DESIGN AND METHODS: We studied 28 obese, sedentary postmenopausal Caucasian women. Women taking oral estrogen (n = 6) were matched for age (57 +/- 3 vs. 58 +/- 2 years), weight (87.9 +/- 6.0 vs. 83.0 +/- 3.9 kg), and BMI (33.9 +/- 1.7 vs. 33.9 +/- 1.9 kg/m(2)) with women not on HRT (n = 6). Eight women taking oral estrogen plus progesterone were matched with eight different women not on HRT for age (59 +/- 2 vs. 60 +/- 2 years), weight (82.8 +/- 3.7 vs. 83.7 +/- 4.1 kg), and BMI (30.7 +/- 1.0 vs. 29.9 +/- 1.3 kg/m(2)). RESULTS: VO(2max) (maximal aerobic capacity), percentage of fat, total body fat mass, and fat-free mass (FFM) were similar between groups. Visceral fat, subcutaneous abdominal fat, sagittal diameter, and mid-thigh low-density lean tissue (intramuscular fat) did not differ by hormone status. Basal carbohydrate and fat utilization was not different among groups. Fasting plasma glucose and insulin did not differ by hormone use. Glucose utilization (M) was measured during the last 30 min of a 3-h hyperinsulinemic-euglycemic clamp (40 mU. m(2). min(-1)). Postmenopausal women taking oral estrogen had a 31% lower M than women not on HRT (42.7 +/- 4.0 vs. 61.7 +/- 4.7 micromol. kg(FFM). min(-1), P < 0.05). M was 26% lower in women taking estrogen plus progesterone (44.0 +/- 3.5 vs. 59.7 +/- 6.2 micromol. kg(FFM). min(-1), P < 0.05) than women not on HRT. M/I, the amount of glucose metabolized per unit of plasma insulin (I), an index of insulin sensitivity, was 36% lower in women taking estrogen compared with matched women not on HRT (P < 0.05) and 28% lower in women taking estrogen plus progesterone compared with matched women not on HRT (P < 0.05). CONCLUSIONS: Postmenopausal women taking oral estrogen or those taking a combination of estrogen and HRT are more insulin-resistant than women not on HRT, even when women are of comparable total and abdominal adiposity.

Visceral adipose tissue cutoffs associated with metabolic risk factors for coronary heart disease in women.

OBJECTIVE: This study determined whether there is a critical level of visceral adipose tissue (VAT) associated with elevated coronary heart disease (CHD) risk factors in a cohort of women >45 years of age. RESEARCH DESIGN AND METHODS: Measurements of body composition (dual-energy X-ray absorptiometry), body fat distribution (computed tomography), fasting and 2-h postprandial (75-g) glucose concentrations, and fasting lipoprotein lipid and insulin concentrations were performed in 233 perimenopausal (9%) and postmenopausal women (age 59 +/- 6 years, 79% Caucasian, 16% on hormone replacement therapy). RESULTS: Women in the lowest VAT quintile (< or =105 cm(2)) had higher concentrations of HDL and HDL(2) cholesterol, lower LDL/HDL cholesterol ratios and triglyceride concentrations, and lower fasting glucose and insulin concentrations than women in the remaining four quintiles (P values <0.05-0.001). Women in the second lowest VAT quintile (106-139 cm(2)) had higher HDL and HDL(2) cholesterol and lower LDL/HDL ratios than women with a VAT > or =163 cm(2) (P < 0.05). Logistic regression analyses showed that women with a VAT of 106-162 cm(2) are 2.5 times more likely to have a low HDL cholesterol (P < 0.05), while women with a VAT > or =163 cm(2) are 5.5 times more likely to have a low HDL cholesterol (P < 0.01) and approximately 4.0 times more likely to have a high LDL/HDL ratio (P < 0.05) compared with women with a VAT < or =105 cm(2). Women with a VAT > or =163 cm(2) are at a higher risk of having impaired glucose tolerance (P < 0.01). CONCLUSIONS: A VAT > or =106 cm(2) is associated with an elevated risk, and a VAT > or =163 cm(2) with an even greater risk, for these metabolic CHD risk factors compared with women with a VAT < or =105 cm(2). These values may prove useful for defining "visceral obesity" and for identifying women most likely to benefit from preventative interventions.

Plasma adiponectin and leptin levels, body composition, and glucose utilization in adult women with wide ranges of age and obesity.

OBJECTIVE: The purpose of this study was to determine the relationships between plasma adiponectin and leptin levels, total and central obesity, and glucose utilization across the adult age span. RESEARCH DESIGN AND METHODS: We studied 148 women aged 18-81 years with a BMI range of 17.2-44.3 kg/m(2). Total percent body fat was determined by dual-energy X-ray absorptiometry and abdominal fat by computed tomography. Glucose tolerance in non-type 2 diabetic volunteers was determined with an oral glucose tolerance test. Glucose utilization (M) was measured during the last 60 min of hyperinsulinemic-euglycemic clamps (240 pmol x m(-2) x min(-1)). Plasma adiponectin levels were measured by radioimmunoassay. The women were separated into three age-groups: young, middle, and old (<40, 40-59, and >or=60 years, respectively), as well as by glucose tolerance status. RESULTS: Adiponectin concentrations did not differ by age-groups. There were significant age effects for BMI, percent body fat, visceral fat, subcutaneous abdominal fat, VO(2max), and M. Adiponectin levels were lower in the prediabetic women (n = 18) than in the normal glucose-tolerant women (n = 108) and the women with type 2 diabetes (n = 22) (both P < 0.05). Univariate correlations revealed significant negative relationships between plasma adiponectin levels and BMI, percent body fat, visceral fat, subcutaneous abdominal fat, fasting leptin, and fasting insulin and positive relationship with M (all P < 0.05). In a multiple stepwise regression model to predict adiponectin, only M remained in the model at P < 0.001. Multivariate analyses revealed a significant relation for M as a function of adiponectin, insulin, and VO(2max). CONCLUSIONS: The data suggest that plasma adiponectin does not change with age but levels are negatively associated with percent body fat, visceral fat, subcutaneous abdominal fat, insulin, and leptin levels in women. Adiponectin is positively associated with M across the age span in women.