Elevated soluble intercellular adhesion molecule-1 levels in obesity: relationship to insulin resistance and tumor necrosis factor-alpha system activity

Antisense oligonucleotide-mediated knockdown of Mpzl3 attenuates the negative metabolic effects of diet-induced obesity in mice

Previously, we demonstrated that global knockout (KO) of the gene encoding myelin protein zero‐like 3 (Mpzl3) results in reduced body weight and adiposity, increased energy expenditure, and reduced hepatic lipid synthesis in mice. These mice also exhibit cyclic and progressive alopecia which may contribute to the observed hypermetabolic phenotype. The goal of the current study was to determine if acute and peripherally restricted knockdown of Mpzl3 could ameliorate the negative metabolic effects of exposure to a high‐fat and sucrose, energy‐dense (HED) diet similar to what was observed in global Mpzl3 KO mice in the absence of a skin phenotype. Mpzl3 antisense oligonucleotide (ASO) administration dose‐dependently decreased fat mass and circulating lipids in HED‐fed C57BL/6N mice. These changes were accompanied by a decrease in respiratory exchange ratio, a reduction in energy expenditure and food intake, a decrease in expression of genes regulating de novo lipogenesis in white adipose tissue, and an upregulation of genes associated with steroid hormone biosynthesis in liver, thermogenesis in brown adipose tissue and fatty acid transport in skeletal muscle. These data demonstrate that resistance to the negative metabolic effects of HED is a direct effect of Mpzl3 knockdown, rather than compensatory changes that could be associated with deletion of Mpzl3 during development in global KO mice. Inhibiting MPZL3 could be a potential therapeutic approach for the treatment of obesity and associated dyslipidemia.

Hydroxytyrosol Modulates Adipocyte Gene and miRNA Expression Under Inflammatory Condition

Chronic inflammation of the adipose tissue (AT) is a major contributor to obesity-associated cardiometabolic complications. The olive oil polyphenol hydroxytyrosol (HT) contributes to Mediterranean diet cardiometabolic benefits through mechanisms still partially unknown. We investigated HT (1 and 10 μmol/L) effects on gene expression (mRNA and microRNA) related to inflammation induced by 10 ng/mL tumor necrosis factor (TNF)-α in human Simpson–Golabi–Behmel Syndrome (SGBS) adipocytes. At real-time PCR, HT significantly inhibited TNF-α-induced mRNA levels, of monocyte chemoattractant protein-1, C-X-C Motif Ligand-10, interleukin (IL)-1β, IL-6, vascular endothelial growth factor, plasminogen activator inhibitor-1, cyclooxygenase-2, macrophage colony-stimulating factor, matrix metalloproteinase-2, Cu/Zn superoxide dismutase-1, and glutathione peroxidase, as well as surface expression of intercellular adhesion molecule-1, and reverted the TNF-α-mediated inhibition of endothelial nitric oxide synthase, peroxisome proliferator-activated receptor coactivator-1α, and glucose transporter-4. We found similar effects in adipocytes stimulated by macrophage-conditioned media. Accordingly, HT significantly counteracted miR-155-5p, miR-34a-5p, and let-7c-5p expression in both cells and exosomes, and prevented NF-κB activation and production of reactive oxygen species. HT can therefore modulate adipocyte gene expression profile through mechanisms involving a reduction of oxidative stress and NF-κB inhibition. By such mechanisms, HT may blunt macrophage recruitment and improve AT inflammation, preventing the deregulation of pathways involved in obesity-related diseases.

Metformin Monotherapy Downregulates Diabetes-Associated Inflammatory Status and Impacts on Mortality

Aging is the main risk factor for developing diabetes and other age-related diseases. One of the most common features of age-related comorbidities is the presence of low-grade chronic inflammation. This is also the case of metabolic syndrome and diabetes. At the subclinical level, a pro-inflammatory phenotype was shown to be associated with Type-2 diabetes mellitus (T2DM). This low to mid-grade inflammation is also present in elderly individuals and has been termed inflammaging. Whether inflammation is a component of aging or exclusively associated with age-related diseases in not entirely known. We used clinical data and biological readouts in a group of individuals stratified by age, diabetes status and comorbidities to investigate this aspect. While aging is the main predisposing factor for several diseases there is a concomitant increased level of pro-inflammatory cytokines. DM patients show an increased level of sTNFRll, sICAM-1, and TIMP-1 when compared to Healthy, Non-DM and Pre-DM individuals. These inflammatory molecules are also associated with insulin resistance and metabolic syndrome in Non-DM and pre-DM individuals. We also show that metformin monotherapy was associated with significantly lower levels of inflammatory molecules, like TNFα, sTNFRI, and sTNFRII, when compared to other monotherapies. Longitudinal follow up indicates a higher proportion of death occurs in individuals taking other monotherapies compared to metformin monotherapy. Together our finding shows that chronic inflammation is present in healthy elderly individuals and exacerbated with diabetes patients. Likewise, metformin could help target age-related chronic inflammation in general, and reduce the predisposition to comorbidities and mortality.

Impact of Exercise on Inflammatory Mediators of Metabolic and Vascular Insulin Resistance in Type 2 Diabetes

The development of obesity is cornerstone in the etiology of metabolic and vascular insulin resistance and consequently exacerbates glycemic control. Exercise is an efficacious first-line therapy for type 2 diabetes that improves insulin action through, in part, reducing hormone mediated inflammation. Together, improving the coordination of skeletal muscle metabolism with vascular delivery of glucose will be required for optimizing type 2 diabetes and cardiovascular disease treatment.

High circulating levels of sICAM-1 and sVCAM-1 in the patients with Hashimoto's thyroiditis

OBJECTIVE

To investigate whether soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) levels are increased in euthyroid patients with Hashimoto's thyroiditis (HT) and whether they are associated with thyroid autoimmunity and metabolic parameters.

DESIGN

Cross-sectional.

SUBJECTS AND METHODS

In total, 80 euthyroid patients with HT and 80 age- and body mass index (BMI)-matched control participants were included. Serum sICAM-1, sVCAM-1, free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (anti-TPO), thyroglobulin antibody (anti-TG), fasting blood glucose (FBG), insulin, and lipid levels and homeostasis model assessment for insulin resistance (HOMA-IR) were assessed in all participants.

RESULTS

The patients with HT had significantly higher levels of sICAM-1 and sVCAM-1 than controls (both p < 0.001). The difference was sustained after adjustment for TSH and levothyroxine use. Regression analysis demonstrated that sICAM-1 was related to anti-TPO (p < 0.001), and sVCAM-1 was related to both anti-TPO and-TG (p < 0.001 and p = 0.03, respectively); this relationship was sustained after adjustment for age and BMI. Although FBG and HOMA-IR were higher in the HT group, logistic regression analysis revealed that there was no effect of anti-TPO, anti-TG, sICAM-1, sVCAM-1, and C-reactive protein (CRP) on the occurrence of high FBG and high HOMA-IR.

CONCLUSION

sICAM-1 and sVCAM-1 levels were significantly elevated in the patients with euthyroid HT and correlated closely with thyroid autoimmunity. However, soluble adhesion molecules had no relation with glucose metabolism parameters in the HT patients.

Plasma levels of cell adhesion molecules during hyperinsulinemia and modulation of vasoactive mediators

Endothelial expression of cell adhesion molecules (CAMs) plays an important role in atherosclerosis. Atherosclerosis is increased in hyperinsulinemic states, but whether insulin per se is proatherogenic remains unclear. To investigate the effects of hyperinsulinemia on CAM expression, plasma levels of ICAM-1, VCAM-1 and E-selectin were measured before and after forearm infusion of insulin in healthy subjects. Insulin administration for 2 h resulted in signifi-cant hyperinsulinemia, whereas no significant change was observed in soluble CAMs (all p > 0.05). Because insulin stimulates endothelial release of both endothelin-1 (ET-1) and nitric oxide (NO), which may modulate the expression of CAMs, we also investigated the response of CAMs to ET-1 receptor blockade, alone and in combination with NO synthesis inhibition. ET-1 receptor blockade during hyperinsulinemia resulted in a vasodilator response, but did not affect soluble CAMs (all p > 0.05). Superimposition of NO inhibition by l-NMMA reversed the vasodilator effect of ET-1 blockade, without affecting soluble CAMs (all p > 0.05). In conclusion, acute hyperinsulinemia, alone or during ET-1 and NO pathway blockade, does not affect soluble CAMs. These results do not support a direct effect of insulin on endothelial cells to affect leukocyte adhesiveness to the vascular wall.

Association of serum uric acid levels to inflammation biomarkers and endothelial dysfunction in obese prepubertal children

BACKGROUND

High serum uric acid (SUA) levels are present in patients with metabolic syndrome (MetS), when the latter is associated with endothelial dysfunction, inflammation, and hypertension. This increase in SUA levels may have a key role in cardiovascular diseases.

OBJECTIVE

We aim to quantify the differences in inflammation biomarkers, endothelial dysfunction, and parameters associated with MetS in obese prepubertal children compared to non-obese children, and determine if there is a relationship between uric acid levels and these variables.

METHODS

A cross-sectional study was carried out on obese children (6-9 yr old). The study included 43 obese children and the same number of non-obese children (control group), matched by age and sex. SUA, C-reactive protein (CRP), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1), glucose, insulin, lipid profile, and blood pressure were all measured.

RESULTS

SUA levels, CRP, and sICAM-1 were significantly higher in obese children. In the obese group, SUA levels showed a positive correlation with body mass index (BMI), insulin, homeostasis model assessment for insulin resistance (HOMA-IR), CRP, IL-6, sICAM-1, and triglycerides (TGs), and correlated negatively with high-density lipoprotein cholesterol (HDL-C) and Apo-AI, but not with Apo-B. When adjusted for age, sex, and creatinine, it was noted that SUA levels are independent predictive factors for sICAM-1, CRP, and IL-6.

CONCLUSIONS

Inflammation biomarkers, endothelial dysfunction, and parameters associated with MetS are elevated in obese prepubertal children and correlate to uric acid levels.

Dietary grape powder increases IL-1β and IL-6 production by lipopolysaccharide-activated monocytes and reduces plasma concentrations of large LDL and large LDL-cholesterol particles in obese humans

Obese individuals are at an increased risk of developing CVD, hypertension, type 2 diabetes, and bacterial and viral infections when compared with the normal-weight population. In a 9-week randomised, double-blind, cross-over study, twenty-four obese subjects aged between 20 and 60 years and with a BMI between 30 and 45 kg/m2were fed grape or placebo powder for 3-week intervals to determine the effects of dietary grapes on blood lipid profiles, plasma inflammatory marker concentrations and immune cell function. Blood samples were collected on days 1 and 8 for obtaining baseline information and at weeks 3, 4, 8 and 9. Comprehensive chemistry panels, lipid profile analyses by NMR, measurement of plasma inflammatory marker concentrations, and analyses of cytokine production by activated T lymphocytes and monocytes were performed for each blood draw. Dietary grape powder reduced the plasma concentrations of large LDL-cholesterol and large LDL particles compared with the placebo powder (P< 0·05). The concentrations of interferon-γ, TNF-α, IL-4 and IL-10 were measured in supernatants from peripheral blood mononuclear cells (PBMC) activated with anti-CD3/CD28 antibodies and those of TNF-α, IL-1β, IL-6 and IL-8 were measured in supernatants from PBMC activated with lipopolysaccharide (LPS). No difference in the production of T-cell cytokines was observed between the two intervention groups. The production of IL-1β and IL-6 was increased in supernatants from LPS-activated PBMC in the grape powder group compared with the placebo powder group (P< 0·05). These data suggest that dietary grapes may decrease atherogenic lipid fractions in obese individuals and increase the sensitivity of monocytes in a population at a greater risk of developing infections.

Genetic ablation of myelin protein zero-like 3 in mice increases energy expenditure, improves glycemic control, and reduces hepatic lipid synthesis

Obesity continues to be a global health problem, and thus it is imperative that new pathways regulating energy balance be identified. Recently, it was reported: (Hayashi K, Cao T, Passmore H, Jourdan-Le Saux C, Fogelgren B, Khan S, Hornstra I, Kim Y, Hayashi M, Csiszar K. J Invest Dermatol 123: 864-871, 2004) that mice carrying a missense mutation in myelin protein zero-like 3 (Mpzl3rc) have reduced body weight. To determine how Mpzl3 controls energy balance in vivo, we generated mice deficient in myelin protein zero-like 3 (Mpzl3-KO). Interestingly, KO mice were hyperphagic yet had reduced body weight and fat mass. Moreover, KO mice were highly resistant to body weight and fat mass gain after exposure to a high-fat, energy-dense diet. These effects on body weight and adiposity were driven, in part, by a pronounced increase in whole body energy expenditure levels in KO mice. KO mice also had reduced blood glucose levels during an intraperitoneal glucose challenge and significant reductions in circulating insulin levels suggesting an increase in insulin sensitivity. In addition, there was an overall increase in oxidative capacity and contractile force in skeletal muscle isolated from KO mice. Hepatic triglyceride levels were reduced by 92% in livers of KO mice, in part due to a reduction in de novo lipid synthesis. Interestingly, Mpzl3 mRNA expression in liver was increased in diet-induced obese mice. Moreover, KO mice exhibited an increase in insulin-stimulated Akt signaling in the liver, further demonstrating that Mpzl3 can regulate insulin sensitivity in this tissue. We have determined that Mpzl3 has a novel physiological role in controlling body weight regulation, energy expenditure, glycemic control, and hepatic triglyceride synthesis in mice.

Contributions of body mass index and exercise habits on inflammatory markers: a cohort study of middle-aged adults living in the USA

OBJECTIVES

Determine whether body mass index (BMI) and physical activity (PA) above, at or below MET minute per week (MMW) levels recommended in the 2008 Physical Activity Guidelines interact or have additive effects on interleukin (IL)-6, C reactive protein (CRP), fibrinogen, interleukin6 (IL-6) soluble receptor (IL-6sr), soluble E-selectin and soluble intracellular adhesion molecule (sICAM)-1.

DESIGN

Archived cohort data (n=1254, age 54.5±11.7 year, BMI 29.8±6.6 kg/m(2)) from the National Survey of Midlife Development in the USA (MIDUS) Biomarkers Study were analysed for concentrations of inflammatory markers using general linear models. MMW was defined as no regular exercise, <500 MMW, 500-1000 MMW, >1000 MMW and BMI was defined as <25, 25-29.9, ≥30 kg/m(2). Analyses were adjusted for age, sex, smoking and relevant medication use.

SETTING

Respondents reported to three centres to complete questionnaires and provide blood samples.

PARTICIPANTS

Participants were men and women currently enroled in the MIDUS Biomarker Project (n=1254, 93% non-Hispanic white, average age 54.5 years).

PRIMARY OUTCOME MEASURES

Concentration of serum IL-6, CRP, fibrinogen, IL-6sr, sE-selectin and sICAM.

RESULTS

Significant interactions were found between BMI and MMW for CRP and sICAM-1 (p<0.05). CRP in overweight individuals was similar to that in obese individuals when no PA was reported, but it was similar to normal weight when any level of regular PA was reported. sICAM-1 was differentially lower in obese individuals who reported >1000 MMW compared to obese individuals reporting less exercise.

CONCLUSIONS

The association of exercise with CRP and sICAM-1 differed by BMI, suggesting that regular exercise may buffer weight-associated elevations in CRP in overweight individuals while higher levels of exercise may be necessary to reduce sICAM-1 or CRP in obese individuals.

Effects of dietary strawberry powder on blood lipids and inflammatory markers in obese human subjects

Obesity is a strong risk factor for the development of CVD, hypertension and type 2 diabetes. The overall goal of the present pilot study was to feed strawberries, in the form of freeze-dried powder, to obese subjects to determine whether dietary strawberries beneficially altered lipid profiles and reduced blood markers of inflammation compared with a control intervention. A total of twenty healthy subjects (thirteen females and seven males) aged between 20 and 50 years with a BMI between 30 and 40 kg/m2 completed the present 7-week double-blind, randomised, cross-over trial. Each subject received a prepared diet 7 d/week for 7 weeks consisting of approximately 35 % of energy from fat, 20 % protein, 45 % carbohydrate and 14 g fibre. Blood was collected on days 1 and 8 for baseline information. After the first week, subjects were randomly assigned to the strawberry powder (equivalent to four servings of frozen strawberries) or control (strawberry-flavoured) intervention for 3 weeks. For the remaining 3 weeks, subjects crossed over to the opposite intervention. Blood was collected again at the end of weeks 3, 4, 6 and 7. A comprehensive chemistry panel, lipid profile analyses and measurement of inflammatory mediators were performed for each blood draw. A 3-week dietary intervention with strawberry powder reduced plasma concentrations of cholesterol and small HDL-cholesterol particles, and increased LDL particle size in obese subjects (P < 0·05). Dietary strawberry powder reduced risk factors for CVD, stroke and diabetes in obese volunteers, suggesting a potential role for strawberries as a dietary means to decrease obesity-related disease.

Increased leptin/leptin receptor pathway affects systemic and airway inflammation in COPD former smokers

Background

Leptin, a hormone produced mainly by adipose tissue, regulates food intake and energy expenditure. It is involved in inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and its deficiency is associated with increased susceptibility to the infection. The leptin receptor is expressed in the lung and in the neutrophils.

Methods

We measured the levels of leptin, tumor necrosis factor alpha (TNF-α) and soluble form of intercellular adhesion molecule-1 (sICAM-1) in sputum and plasma from 27 smoker and former smoker patients with stable COPD using ELISA methods. Further we analyzed leptin and its receptor expression in sputum cells from 16 COPD patients using immunocytochemistry.

Results

In plasma of COPD patients, leptin was inversely correlated with TNF-α and positively correlated with the patient weight, whereas the levels of sICAM-1 were positively correlated with TNF-α. In sputum of COPD patients leptin levels were correlated with forced expiratory volume in 1 second/forced vitality capacity. Additionally, increased levels of sputum leptin and TNF-α were observed in COPD former smokers rather than smokers. Further the expression of leptin receptor in sputum neutrophils was significantly higher in COPD former smokers than in smokers, and the expression of leptin and its receptor was positively correlated in neutrophils of COPD former smokers.

Conclusion

Our findings suggest a role of leptin in the local and systemic inflammation of COPD and, taking into account the involvement of neutrophils in this inflammatory disease, describe a novel aspect of the leptin/leptin receptor pathway in the regulation of host defense after smoking cessation.

Prepregnancy obesity and sFlt1-induced preeclampsia in mice: developmental programming model of metabolic syndrome

OBJECTIVE

We sought to establish a model of fetal programming of metabolic syndrome by exposure to soluble fms-like tyrosine kinase-1 (sFlt1)-induced preeclampsia (PE) and preexisting maternal obesity (MO).

STUDY DESIGN

CD-1 female mice were placed on either standard or high-fat diet for 3 months. On day 8 of pregnancy, mice were injected with either adenovirus-carrying sFlt1 or adenovirus-carrying murine immunoglobulin G2α Fc fragment. Offspring were studied at 6 months of age.

RESULTS

Exposure to MO with/without PE resulted in significant increase in progeny's weight and adiposity. Blood pressure in males was significantly increased due to MO with PE. Metabolic blood analytes were affected in males and females exposed to only PE or MO with/without PE; inflammatory-in females exposed to MO with/without PE and males born to MO with PE; atherosclerotic-in females exposed to MO.

CONCLUSION

Exposure to maternal prepregnancy obesity and sFlt1-induced preeclampsia alter the offspring's blood pressure, metabolic, inflammatory, and atherosclerotic profiles later in life.

P-selectin glycoprotein ligand-1 deficiency is protective against obesity-related insulin resistance

OBJECTIVE

An inflammatory process is involved in the mechanism of obesity-related insulin resistance. Recent studies indicate that monocyte chemoattractant protein-1 (MCP-1) is a major chemokine that promotes monocyte infiltration into adipose tissues; however, the adhesion pathway in adipose tissues remains unclear. We aimed to clarify the adhesion molecules that mediate monocyte infiltration into adipose tissue.

RESEARCH DESIGN AND METHODS

We used a DNA microarray to compare the gene expression profiles in epididymal white adipose tissues (eWAT) between db/db mice and C57/BL6 mice each fed a high-fat diet (HFD) or a low-fat diet (LFD). We investigated the change of insulin resistance and inflammation in eWAT in P-selectin glycoprotein ligand-1 (PSGL-1) homozygous knockout (PSGL-1⁻(/)⁻) mice compared with wild-type (WT) mice fed HFD.

RESULTS

DNA microarray analysis revealed that PSGL-1, a major ligand for selectins, is upregulated in eWAT from both db/db mice and WT mice fed HFD. Quantitative real-time RT-PCR and immunohistochemistry showed that PSGL-1 is expressed on both endothelial cells and macrophages in eWAT of obese mice. PSGL-1⁻(/)⁻ mice fed HFD showed a remarkable reduction of macrophage accumulation and expression of proinflammatory genes, including MCP-1 in eWAT. Moreover, adipocyte hypertrophy, insulin resistance, lipid metabolism, and hepatic fatty change were improved in PSGL-1⁻(/) ⁻mice compared with WT mice fed HFD.

CONCLUSIONS

These results indicate that PSGL-1 is a crucial adhesion molecule for the recruitment of monocytes into adipose tissues in obese mice, making it a candidate for a novel therapeutic target for the prevention of obesity-related insulin resistance.

Calcium channel blocker nilvadipine, but not diltiazem, inhibits ocular inflammation in endotoxin-induced uveitis

PURPOSE

Calcium channel blockers (CCBs), widely used for hypertensive patients, have recently been shown to inhibit atherosclerosis by their antioxidative action. The aim of the present study was to examine whether the CCBs nilvadipine and diltiazem reduce ocular inflammation in endotoxin-induced uveitis (EIU).

METHODS

EIU was induced in male C57/B6 mice with a single intraperitoneal injection of lipopolysaccharide (LPS). The animals received intraperitoneal injections of either nilvadipine, diltiazem, or vehicle for 5 days before the LPS application. Twenty-four hours after EIU induction, adherent leukocytes to the retinal vasculature were counted with a concanavalin A lectin perfusion-labeling technique. The protein concentration in the aqueous humor was measured to assess blood-ocular barrier breakdown. Retinal levels of intercellular adhesion molecule (ICAM)-1 and monocyte chemotactic protein (MCP)-1 were analyzed by enzyme-linked immunosorbent assay. LPS-stimulated generation of superoxide in murine microvascular endothelial cells was examined with a nitroblue tetrazolium assay.

RESULTS

Compared to vehicle treatment, application of nilvadipine, but not diltiazem, led to significant suppression of EIU-associated retinal leukocyte adhesion, together with anterior-chamber protein leakage, retinal expression of ICAM-1 and MCP-1, and LPS-induced superoxide generation in vitro.

CONCLUSIONS

The CCB nilvadipine exercises an inhibitory effect on the pathogenesis of ocular inflammation through the suppression of inflammation-related molecules.

[Soluble intercellular adhesion molecule-1 and C reactive protein after bariatric surgery]

BACKGROUND AND OBJECTIVES

Obesity is associated with a state of chronic low-grade inflammation. A causal association between inflammatory processes and atherogenesis has been proposed. The aim of this study was to evaluate changes in the proinflammatory profile of morbidly obese patients who underwent bariatric surgery. Serum C-reactive protein (CRP) and soluble intercellular adhesion molecule-1 (sICAM-1) concentrations were measured before and after massive weight loss due to gastric bypass.

METHODS

In this prospective study we measured CRP and sICAM-1 concentrations in 50 morbidly obese patients (19 men and 31 women) at baseline and 3, 6 and 12 months after gastric bypass.

RESULTS

Body mass index (BMI), CRP, and sICAM-1 decreased significantly. BMI correlated with CRP but not with sICAM-1.

CONCLUSIONS

The improvement in vascular risk profile after weight loss in morbidly obese patients could be partially explained by changes in inflammatory status.

Pioglitazone improves lipid and insulin levels in overweight rats on a high cholesterol and fructose diet by decreasing hepatic inflammation

BACKGROUND AND PURPOSE

Nutrient overload leads to obesity and insulin resistance. Pioglitazone, a selective peroxisome proliferator-activated receptor (PPAR)gamma agonist, is currently used to manage insulin resistance, but the specific molecular mechanisms activated by PPARgamma are not yet fully understood. Recent studies suggest the involvement of suppressor of cytokine signalling (SOCS)-3 in the pathogenesis of insulin resistance. This study aimed to investigate the hepatic signalling pathway activated by PPARgamma activation in a non-genetic insulin-resistant animal model.

EXPERIMENTAL APPROACH

Male Wistar rats were maintained on a high-cholesterol fructose (HCF) diet for 15 weeks. Pioglitazone (3 mg x kg(-1)) was administered orally for the last 4 weeks of this diet. At the end of the treatment, serum was collected for biochemical analysis. Levels of PPARgamma, SOCS-3, pro-inflammatory markers, insulin receptor substrate-2 and Akt/glycogen synthase kinase-3beta phosphorylation were assessed in rat liver.

KEY RESULTS

Rats fed the HCF diet exhibited hyperlipidemia, hyperinsulinemia, impaired glucose tolerance and insulin resistance. Pioglitazone administration evoked a significant improvement in lipid metabolism and insulin responsiveness. This was accompanied by reduced hepatic expression of SOCS-3, interleukin-6, tumour necrosis factor-alpha and markers of neutrophil infiltration. Diet-induced PPARgamma expression was unaffected by the pioglitazone treatment.

CONCLUSION AND IMPLICATIONS

Chronic pioglitazone administration reduced hepatic inflammatory responses in rats fed a HCF diet. These effects were associated with changes in hepatic expression of SOCS-3, which may be a crucial link between the reduced local inflammation and the improved insulin signalling.

Effects of lifestyle measures, antiobesity agents, and bariatric surgery on serological markers of inflammation in obese patients

Overweight and obesity are highly prevalent in developed countries and are also becoming more frequent in the developing world. Overweight and obese patients have elevated levels of several inflammatory markers and this inflammatory state might contribute to their increased vascular risk. We summarize the effects of lifestyle changes, antiobesity agents, and bariatric surgery on serological inflammatory markers in overweight and obese patients. Most studies showed a decrease in inflammation with all 3 interventions. However, it remains to be established whether the decrease in inflammatory markers induced by lifestyle changes or (where indicated) with antiobesity agents or bariatric surgery will translate into reduced vascular morbidity and mortality in overweight and obese patients.

Changes in body mass index are associated with changes in inflammatory and endothelial dysfunction biomarkers in obese prepubertal children after 9 months of body mass index SD score loss

The metabolic syndrome is associated with insulin resistance, a systemic low-grade inflammatory state, and endothelial dysfunction. These disorders may arise at a very early age in obese children. The aim of this study was to confirm changes in endothelial dysfunction and inflammatory biomarkers in obese prepubertal children and to evaluate the effect of body mass index (BMI) modification on these biomarkers. Biomarkers for inflammation, endothelial dysfunction, and insulin resistance were measured in obese children (47) and healthy controls (47). Baseline pretreatment levels of insulin (P = .019), homeostasis model assessment of insulin resistance (P = .004), soluble intercellular adhesion molecule (sICAM) (P = .003), and C-reactive protein (CRP) (P < .001) were significantly higher in obese children than in controls. After 9 months of treatment, obese children with lowered BMI SD score (SDS-BMI) displayed a significant decrease in insulin (P = .011), homeostasis model assessment of insulin resistance (P = .012), CRP (P = .006), and interleukin-6 (IL-6) (P = .045) levels compared with obese children with stable SDS-BMI; they also displayed a nonsignificant drop in sICAM levels. Similarly, obese children with lowered SDS-BMI displayed a decrease in CRP (P = .005) and IL-6 (P = .065) compared with baseline levels before treatment. In the total obese group, changes in SDS-BMI correlated positively with changes in CRP (P = .035), IL-6 (P = .027), and sICAM-1 (P = .038) levels. Only SDS-BMI was an independent predictive factor for CRP (P = .031), IL-6 (P = .027), and sICAM-1 (P = .033). Prepubertal obese children displayed alterations indicative of endothelial dysfunction, insulin resistance, and inflammatory state. Lowering of the SDS-BMI after 9 months of treatment was associated with an improvement in these variables compared with those in obese children with stable SDS-BMI status.

Macrophage content in subcutaneous adipose tissue: associations with adiposity, age, inflammatory markers, and whole-body insulin action in healthy Pima Indians

OBJECTIVE

In severely obese individuals and patients with diabetes, accumulation and activation of macrophages in adipose tissue has been implicated in the development of obesity-associated complications, including insulin resistance. We sought to determine whether in a healthy population, adiposity, sex, age, or insulin action is associated with adipose tissue macrophage content (ATMc) and/or markers of macrophage activation.

RESEARCH DESIGN AND METHODS

Subcutaneous ATMc from young adult Pima Indians with a wide range of adiposity (13-46% body fat, by whole-body dual-energy X-ray absorptiometry) and insulin action (glucose disposal rate 1.6-9 mg/kg estimated metabolic body size/min, by glucose clamp) were measured. We also measured expression in adipose tissue of factors implicated in macrophage recruitment and activation to determine any association with ATMc and insulin action.

RESULTS

ATMc, as assessed by immunohistochemistry (Mphi) and by macrophage-specific gene expression (CD68, CD11b, and CSF1R), were correlated with percent body fat, age, and female sex. Gene expression of CD68, CD11b, and CSF1R but not Mphi was correlated negatively with glucose disposal rate but not after adjustment for percent body fat, age, and sex. However, adipose tissue expression of plasminogen activator inhibitor type-1 (PAI-1) and CD11 antigen-like family member C (CD11c), markers produced by macrophages, were negatively correlated with adjusted glucose disposal rate (r = -0.28, P = 0.05 and r = -0.31, P = 0.03).

CONCLUSIONS

ATMc is correlated with age and adiposity but not with insulin action independent of adiposity in healthy human subjects. However, PAI-1 and CD11c expression are independent predictors of insulin action, indicating a possible role for adipose tissue macrophage activation.

Metabolic predictors of inflammation, adhesion, and coagulability in healthy younger-aged adults

Elevated levels of inflammatory biomarkers are associated with the pathophysiology of cardiovascular diseases and are predictors of cardiovascular events. The objective of this study was to determine the unique contributions of metabolic factors as predictors of inflammation (C-reactive protein (CRP) and interleukin-6 (IL-6)), adhesion (soluble intercellular adhesion molecule-1 (sICAM-1)), and coagulation (D-dimer) in healthy younger-aged adults. Participants were 83 women and 92 men (mean age 30.04 years, s.d. +/- 4.8, range 22-39) of normal weight to moderate obese weight (mean BMI 24.4 kg/m(2), s.d. +/- 3.35, range 17-32). The primary data analytical approaches included Pearson correlation and multiple linear regression. Circulating levels of CRP, IL-6, sICAM-1, and D-dimer were determined in plasma. Higher levels of CRP were independently associated with higher BMI, a greater waist-to-hip ratio, female gender, and higher triglycerides (P < 0.001). Higher IL-6 levels were independently associated with a greater waist-to-hip ratio (P < 0.01). Higher levels of sICAM-1 were independently associated with higher BMI, higher triglycerides, and lower insulin resistance (P < 0.001). Higher D-dimer levels were independently associated with higher BMI and being female (P < 0.001). Having a higher BMI was most consistently associated with elevated biomarkers of inflammation, adhesion, and coagulation in this sample of healthy younger-aged adults, although female gender, insulin resistance, and lipid levels were also related to the biomarkers. The findings provide insight into the adverse cardiovascular risk associated with elevated body weight in younger adults.

Quantitative trait locus analysis of circulating adhesion molecules in hyperlipidemic apolipoprotein E-deficient mice

Circulating soluble adhesion molecules have been suggested as useful markers to predict several clinical conditions such as atherosclerosis, type 2 diabetes, obesity, and hypertension. To determine genetic factors influencing plasma levels of soluble vascular cell adhesion molecule-1 (VCAM-1) and P-selectin, quantitative trait locus (QTL) analysis was performed on an intercross between C57BL/6J (B6) and C3H/HeJ (C3H) mouse strains deficient in apolipoprotein E-deficient (apoE-/-). Female F2 mice were fed a western diet for 12 weeks. One significant QTL, named sVcam1 (71 cM, LOD 3.9), on chromosome 9 and three suggestive QTLs on chromosomes 5, 13 and 15 were identified to affect soluble VCAM-1 levels. Soluble P-selectin levels were controlled by one significant QTL, named sSelp1 (8.5 cM, LOD 3.4), on chromosome 16 and two suggestive QTLs on chromosomes 10 and 13. Both adhesion molecules showed significant or an apparent trend of correlations with body weight, total cholesterol, and LDL/VLDL cholesterol levels in the F2 population. These results indicate that plasma VCAM-1 and P-selectin levels are complex traits regulated by multiple genes, and this regulation is conferred, at least partially, by acting on body weight and lipid metabolism in hyperlipidemic apoE-/- mice.

Cellular Adhesion Molecules in Healthy Subjects: Short Term Variations and Relations to Flow Mediated Dilation

The objective was primarily to describe short term intra-individual variation in serum levels of soluble adhesion molecules (sCAMs: E-selectin, P-selectin, intercellular adhesion molecule-1(sICAM-1) and vascular cellular adhesion molecule-1(sVCAM-1)) in healthy subjects. Secondly, sCAMs were correlated to brachial artery flow mediated vasodilation (FMD).

Forty healthy subjects aged 24–66 years had sCAMs measured twice with 4 week intervals and short-term intra-individual variation was estimated as variation in the paired measurements after correcting for the analytical precision of the used method. At baseline, brachial FMD was measured.

No difference was observed in mean sCAMs in the whole study group. Estimated intra-subject variations in sCAMs were 7.6–11.3%. In a regression analysis, significant negative association was found between sE-selectin and FMD after controlling for possible confounders (p < 0.04) while no significant correlation could be demonstrated between the other sCAMs and FMD.

In conclusion, short term intra-individual variations in sCAMs were 7.6–11.3% in healthy subjects. We also found a significant negative association between sE-selectin and FMD, indicating an possible association between inflammation and dysfunction of the vascular endothelium; however further studies are required to confirm this preliminary finding.

Weight loss, but not fish oil consumption, improves fasting and postprandial serum lipids, markers of endothelial function, and inflammatory signatures in moderately obese men

Overweight persons are at risk for cardiovascular diseases, which may relate to a disturbed endothelial function and pro-inflammatory serum profiles. Indeed, weight loss lowers cardiovascular disease risk, but weight maintenance is difficult. Therefore, dietary supplements such as fish oil, which improve endothelial function, are useful. In this study, we evaluated effects of fish oil and moderate weight loss in the same population. For this, 11 normolipidemic healthy, moderately obese men (BMI 30-35 kg/m2) received in random order 1.1 g/d eicosapentanoic acid (EPA) + docosahexanoic acid (DHA) or oleic acid (control) for 6 wk. In the 3rd period, 8 of the 11 subjects consumed low-energy diets (2 MJ/d) for 4 wk followed by 4 wk weight stabilization. Their body weight was reduced by 9.4 +/- 2.0 kg (P < 0.05). On the final day of all 3 periods, a postprandial test was conducted. Weight loss lowered fasting and postprandial plasma triacylglycerol (TG) responses (P < 0.001), whereas fish oil reduced only postprandial TG (P = 0.006). Fish oil did not affect soluble intercellular adhesion molecule (s-ICAM), whereas weight loss reduced fasting (P = 0.009) and postprandial s-ICAM responses (P < 0.001). Fasting s-ICAM and TG correlated (r = 0.68; P = 0.029), as did changes in fasting s-ICAM and TG during weight loss (r = 0.80; P = 0.029) and fish oil treatment (r = 0.76; P = 0.009). Fasting (P = 0.027) and postprandial (P < 0.001) serum C-reactive protein were lowered by weight loss. The postprandial monocyte chemoattractant protein-1 response was lowered by fish oil and after weight loss (P < 0.001). This indicates that 1.1 g/d EPA+DHA supplied for 6 wk, in contrast to approximately 10 kg weight loss, does not improve markers of endothelial function and inflammation.

Circulating levels of endothelial adhesion molecules and risk of diabetes in an ethnically diverse cohort of women

Elevated circulating levels of soluble adhesion molecules as markers of endothelial dysfunction have been related to insulin resistance and its associated metabolic abnormalities. However, their associations with type 2 diabetes remain inconclusive. We conducted a prospective nested case-control study to examine the associations between plasma levels of E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) and diabetes risk among 82,069 initially healthy women aged 50-79 years from the Women's Health Initiative Observational Study. During a median follow-up of 5.9 years, 1,584 incident diabetes case subjects were matched with 2,198 control subjects by age, ethnicity, clinical center, time of blood draw, and follow-up time. Baseline median levels of the biomarkers were each significantly higher among case subjects than among control subjects (E-selectin, 49 vs. 37 ng/ml; ICAM-1, 324 vs. 280 ng/ml; and VCAM-1, 765 vs. 696 ng/ml [all P values <0.001]). After adjustment for risk factors, the relative risks of diabetes among women in the highest quartile versus those in the lowest quartile were 3.46 for E-selectin (95% CI 2.56-4.68; P for trend <0.0001), 2.34 for ICAM-1 (1.75-3.13; P for trend <0.0001), and 1.48 for VCAM-1 (1.07-2.04; P for trend = 0.009). E-selectin and ICAM-1 remain significant in each ethnic group. In conclusion, higher levels of E-selectin and ICAM-1 were consistently associated with increased diabetes risk in a multiethnic cohort of U.S. postmenopausal women, implicating an etiological role of endothelial dysfunction in the pathogenesis of type 2 diabetes.

Endothelial activation markers and their key regulators after restrictive bariatric surgery

OBJECTIVE

Increased plasma levels of endothelial activation markers in obese subjects reflect the positive association between cardiovascular diseases and obesity. The pro-inflammatory state associated with obesity is thought to play a major role in endothelial cell activation in severely obese individuals. Previous studies demonstrated that long-term weight loss after bariatric surgery is accompanied by a decreased proinflammatory state. However, little is known about the long-term effects of bariatric surgery on endothelial cell activation.

RESEARCH METHODS AND PROCEDURES

Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1), soluble endothelial selectin (sE-selectin), and soluble vascular cell adhesion molecule-1 (sVCAM-1), all markers of endothelial cell activation, and of their regulators adiponectin and resistin were measured at different time-points postoperatively in 26 consecutive patients who underwent restrictive surgery, with a follow-up of 2 years.

RESULTS

During the first 6 months after bariatric surgery, sE-selectin levels decreased. Despite substantial weight loss, sICAM-1 and sVCAM-1 plasma levels did not decrease significantly. After 24 months, sICAM-1 levels were significantly decreased, whereas sE-selectin levels were further decreased. However, sVCAM-1 levels remained elevated. Adiponectin levels did not change significantly during the first 6 months after bariatric surgery, whereas resistin levels increased. After 24 months, adiponectin levels were similar to normal-weight controls, but resistin levels remained high.

DISCUSSION

Reductions in plasma levels of different markers of endothelial activation after bariatric surgery show different temporal patterns, suggesting that distinct mechanisms are involved in their regulation. Although not all endothelial activation markers normalize after bariatric surgery, our findings suggest that bariatric surgery can reduce endothelial activation in the long term.

Macrophage infiltration into omental versus subcutaneous fat across different populations: effect of regional adiposity and the comorbidities of obesity

CONTEXT

Macrophage infiltration into adipose tissue has been demonstrated to accompany obesity, with a potential preferential infiltration into intraabdominal vs. sc fat.

OBJECTIVE

Our objective was to determine whether this occurs across different populations with a range of body mass indexes and to assess the relationship with regional adiposity and comorbidity of obesity.

SETTING AND PATIENTS

In two independent cohorts, we used paired omental (OM) and sc fat biopsies from lean controls or predominantly sc or intraabdominally obese persons with minimal comorbidity (n = 60, cohort 1), or from severely obese women with a significant rate of comorbidity (n = 29, cohort 2).

RESULTS

Elevated macrophage infiltration into OM vs. sc fat was observable in lean subjects and exaggerated by obesity, particularly if predominantly intraabdominal. This was paralleled by increased monocyte chemoattractant protein-1 (MCP1) and colony-stimulating factor-1 (CSF1) mRNA levels. Level of CSF1 and MCP1 mRNA correlated with the number of OM macrophages (r = 0.521, P < 0.0001 and r = 0.258, P < 0.051, respectively). In severely obese women (mean body mass index = 43.0 +/- 1.1 kg/m(2)), higher protein expression of both MCP1 and CSF1 was detected in OM vs. sc fat. Number of OM macrophages, but not of sc macrophages, correlated with waist circumference (r = 0.636, P = 0.001 vs. r = 0.170, P = 0.427) and with the number of metabolic syndrome parameters (r = 0.385, P = 0.065 vs. r = -0.158, P = 0.472, respectively). Preferential macrophage infiltration into OM fat was mainly observed in a subgroup in whom obesity was associated with impaired glucose homeostasis.

CONCLUSIONS

Preferential macrophage infiltration into OM fat is a general phenomenon exaggerated by central obesity, potentially linking central adiposity with increased risk of diabetes and coronary heart disease.

ICAM-1 expression in adipose tissue: effects of diet-induced obesity in mice

Obesity has been linked to cardiovascular disease, hypertension, diabetes and the metabolic syndrome, with elevated markers of systemic inflammation. Intercellular adhesion molecule-1 (ICAM-1) is a transmembrane adhesion molecule involved in leukocyte migration to sites of inflammation. In human obesity, elevated expression of the soluble form of ICAM-1 (sICAM-1) is positively correlated with abdominal fat deposition. Increases in adiposity have also been correlated with macrophage infiltration into adipose tissue. Here we investigate adipose tissue production and transcriptional regulation of ICAM-1 in a mouse model of dietary obesity. After feeding mice a high-fat diet, ICAM-1 expression in serum and adipose tissue was analyzed by ELISA, Northern blotting, real-time quantitative PCR, and flow cytometry. After 6 mo on the high-fat diet, sICAM-1 levels significantly correlated with body weight and abdominal fat mass. ICAM-1 mRNA was expressed in adipose tissue of mice, with significantly higher levels in males than females. After only 3 wk, there were adipose tissue-specific increases in mRNAs for ICAM-1, IL-6, and monocyte chemoattractant protein-1 (MCP-1) in male mice. Analysis of the stromal-vascular fraction of male adipose tissue revealed CD11b-negative cells with increased surface ICAM-1 and CD34. We also found two populations of F4/80+, CD11b+, ICAM-1+ cells, one of which also expressed CD14 and CD11c and was increased in response to a high-fat diet. These results indicate that within 3 wk on a high-fat diet, male mice exhibited significant increases in pro-inflammatory factors and immune cell infiltration in adipose tissue that may represent links between obesity and its associated inflammatory complications.

Plasma levels of soluble tumor necrosis factor-alpha receptors are related to total and LDL-cholesterol in lean, but not in obese subjects

Background

Tumor necrosis factor-α (TNFα) is a mediator of insulin resistance. Plasma levels of soluble TNFα receptors (sTNFR1 and sTNFR2) probably reflect paracrine action of the cytokine. TNFα is also a regulator of lipid metabolism, however, data about impact of obesity on the relationships between TNFα and plasma lipids remain controversial.

Aim

The purpose of the present study was to examine the associations of TNFα system with plasma lipids in lean and obese subjects with normal glucose metabolism.

Methods

We examined 63 subjects, 33 lean (BMI<25 kg × m^-2) and 30 with marked overweight or obesity (BMI>27.8 kg × m^-2). Anthropometric and biochemical parameters were measured. Oral glucose tolerance test and euglycemic hyperinsulinemic clamp were also performed.

Results

Obese subjects were markedly more insulin resistant and had higher levels of both TNFα receptors. Total (TC) and LDL-cholesterol (LDL-C), triglycerides (TG) and non-esterified fatty acids (NEFA) were also higher in the obese group. In obese subjects, both receptors were significantly related to TG and HDL-cholesterol (HDL-C), while sTNFR2 was also associated with NEFA. All those correlations disappeared after controlling for insulin sensitivity. In lean subjects, both receptors were related to TC, HDL-C and LDL-C. In that group, sTNFR1 predicted values of all those parameters independently of BMI, plasma glucose and insulin, and insulin sensitivity.

Conclusion

We conclude that TNFα receptors are associated with plasma lipids in different way in lean and in obese subjects. TNFα system is probably important in determining cholesterol levels in lean subjects, while in obese this effect might be masked by other metabolic abnormalities.

Soluble adhesion molecules and marine n-3 fatty acids in patients referred for coronary angiography

OBJECTIVE

To investigate the relationship between soluble cellular adhesion molecules (sCAMs) and the extent of coronary artery disease (CAD) in patients with stable angina pectoris.

METHODS AND RESULTS

Two hundred and ninety-one subjects had fasting levels of circulating intercellular adhesion molecule-1(sICAM-1), vascular cellular adhesion molecule-1 (sVCAM-1), sP-selectin and contents of n-3 polyunsaturated fatty acids (n-3 PUFA) in granulocyte membranes and adipose tissue determined before undergoing elective coronary angiography. Levels of soluble VCAM-1 (983+/-216 versus 893+/-196 ng/l, p<0.001), ICAM-1 (318+/-140 versus 290+/-75 ng/l, p<0.05) and P-selectin (90+/-27 versus 80+/-23 ng/l, p<0.01) were significantly increased in subjects with significant CAD compared to subjects with no significant stenoses. In a linear regression analysis, both sVCAM-1 and sP-selectin, but not sICAM-1, correlated to the presence and the severity of CAD. Both sICAM-1 and sP-selectin were significantly correlated to current smoking status and a history of myocardial infarction. The content of total n-3 PUFA and docosahexaenoic acid in adipose tissue was marginally, but significant positively correlated to VCAM-1.

CONCLUSION

sVCAM-1 and sP-selectin may serve as markers of CAD in patients with stable angina pectoris. Only sVCAM-1 was weakly correlated to n-3 PUFA in adipose tissue.

Elevated soluble ICAM-1 levels induce immune deficiency and increase adiposity in mice

Elevated soluble intercellular adhesion molecule-1 (sICAM-1) levels have been found in many pathological conditions, including obesity. To determine the effects of elevated sICAM-1 on immune responses and metabolism, we generated a transgenic mouse model overexpressing the extracellular domain of mouse ICAM-1 in the liver. The mice, showing 10-fold higher sICAM-1 levels than wild-type mice, presented elevated neutrophil count. Despite this, after intraperitoneal injection of thioglycollate, neutrophil recruitment into the peritoneal cavity was reduced, and the delayed macrophage recruitment was also affected in the transgenic mice compared with wild-type mice. Inhibition of contact hypersensitivity response in the sICAM-1 transgenic mice was comparable to ICAM-1-deficient mice and characterized by significantly less ear swelling and inflammatory cell infiltration than in wild-type mice. sICAM-1transgenic mice were more susceptible to weight gain on a Western-type diet than wild-type mice, and older animals showed excessive fat accumulation, again reminiscent of ICAM-1-deficient mice. Together, these data indicate that sICAM-1 interferes with ICAM-1-mediated cell-cell interactions, which could produce immune-suppressant effects and alteration of metabolism in persons with high levels of this soluble adhesion receptor.

Recombinant methionyl human leptin administration to achieve high physiologic or pharmacologic leptin levels does not alter circulating inflammatory marker levels in humans with leptin sufficiency or excess

A role for high leptin levels in the proinflammatory state associated with obesity has been proposed on the basis of observational studies, but a recent interventional study employing administration of long-acting pegylated leptin resulting in very high pharmacologic levels in obese subjects did not support this idea. These interventional studies have not yet been independently confirmed, however, and varying levels and duration of hyperleptinemia as well as the presence of comorbidities such as diabetes have not yet been investigated as potential effect modifiers. We performed three interventional studies involving administration of recombinant methionyl human leptin (r-metHuLeptin) to lean, otherwise healthy obese, and obese diabetic subjects to investigate whether increasing circulating leptin levels over a wide spectrum of values (from low physiologic to high pharmacologic) would alter serum levels of inflammatory markers and other cytokines important in the T helper cell response. Increasing leptin levels from low physiologic to high physiologic in lean men and from higher physiologic to low pharmacologic in obese men over 3 d did not alter serum interferon-gamma, IL-10, TNF-alpha, monocyte chemoattractant protein-1, or soluble intercellular adhesion molecule-1. In obese subjects with type 2 diabetes mellitus, the administration of r-metHuLeptin for 4 or 16 wk, resulting in high pharmacologic leptin levels, did not activate the TNF-alpha system or increase cytokines or inflammatory markers, including IL-10, IL-6, C-reactive protein, monocyte chemoattractant protein-1, and soluble intercellular adhesion molecule-1. These findings do not support an etiopathogenic role for leptin in proinflammatory states associated with leptin excess such as obesity and have direct relevance for the potential future therapeutic use of r-metHuLeptin in humans.

What is the contribution of differences in three measures of tumor necrosis factor-alpha activity to insulin resistance in healthy volunteers?

To address the potential role that tumor necrosis factor-alpha (TNF-alpha) might play in modulation of insulin resistance in healthy, nondiabetic individuals, we compared plasma TNF-alpha and soluble TNF-alpha receptor 2 (sTNF-R2) concentrations, as well as TNF-alpha polymorphisms, in 94 healthy individuals, stratified into insulin-resistant (IR) and insulin-sensitive (IS) groups based on their plasma insulin concentrations 120 minutes after oral glucose on 2 occasions (1993 and 2000). The IR group (n = 50; 29 men and 21 women) was in the upper quartile and the IS group (n = 44; 24 men and 20 women) in the lowest quartile of the distribution of post-glucose challenge insulin concentrations in a large unselected population (>50 v <23 microU/mL). The IR group had significantly higher values for body mass index, waist-to-hip girth, fasting and post-glucose challenge insulin concentrations, and fasting triglyceride concentrations, and lower high-density lipoprotein cholesterol concentrations as compared to the IS group. Despite the fact that they were relatively more obese, and insulin-resistant, plasma concentrations of TNF-alpha were similar in the IR (1.6 +/- 0.6 pg/mL) and IS (1.7 +/- 0.6 pg/mL) groups, as were the concentrations (5.4 +/- 1.4 v 5.8 +/- 2.0 pg/mL) of sTNF-R2. Furthermore, TNF-alpha polymorphisms (detected by polymerase chain reaction [PCR]) were similar in the 2 groups, with essentially identical allelic frequencies of the 238 (10.3% v 9.4%) and 308 polymorphisms (17.9% v 18.7%). In conclusion, plasma TNF-alpha and sTNF-R2 concentrations, as well as TNF-alpha gene polymorphisms, were not different in healthy volunteers stratified into IR and IS groups on the basis of their plasma insulin response to an oral glucose challenge. Given these data, it does not appear that differences in TNF-alpha activity contribute to the marked variations in insulin action that occur in healthy individuals.

Classic and novel risk factor parameters in women with a history of preeclampsia

Epidemiological studies demonstrate a relation between preeclampsia (PE) and an increased risk of maternal coronary heart disease (CHD) in later life. However, there are few data available to explain any underlying mechanism. We recruited 40 primigravid women with a history of proteinuric PE delivering between 1975 and 1985 and 40 controls, matched as a group for time of index pregnancy, smoking, and current body mass index to assess classic (lipids, blood pressure) and novel (adhesion molecules, insulin, leptin) risk factor pathways. Women with a history of PE had higher diastolic blood pressure compared with controls (83 vs 76 mm Hg, P<0.05), but there were no significant differences in fasting lipoprotein concentrations (P>0.20). However, concentrations of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 (ICAM-1) in particular were higher in the PE group by 14% (P=0.038) and 44% (P=0.002), respectively. The cases also demonstrated a tendency toward higher fasting insulin (P=0.08) concentrations and had higher glycosylated hemoglobin levels (P=0.004). Leptin concentrations were not significantly elevated. Interestingly, significantly more of the women with history of PE were classified as menopausal (37.55% vs 17.5%, P=0.045). The differences in ICAM-1 concentration persisted (P=0.010) after adjustment for potential confounders, including hormonal use/menopausal status, antihypertensive or lipid-lowering therapy, and social class. We conclude that classic risk factors alone cannot fully explain the elevated CHD risk in women with a history of PE. Rather markedly elevated ICAM-1 concentrations and specific but subtle features of the metabolic syndrome (glucose, blood pressure) are likely to be involved.

Soluble tumor necrosis factor-alpha receptors in young obese subjects with normal and impaired glucose tolerance

OBJECTIVE

Tumor necrosis factor-alpha (TNF-alpha) is a possible link between obesity and impaired glucose tolerance (IGT) and type 2 diabetes. Data about TNF-alpha and soluble forms of its receptors (sTNFR1 and sTNFR2) in IGT are controversial. The aim of the present study was to assess plasma TNF-alpha, sTNFR1, and sTNFR2 levels and to evaluate the relationships with insulin resistance in obese subjects with IGT.

RESEARCH DESIGN AND METHODS

A total of 104 subjects participated in the present study: 30 obese subjects with IGT (obese-IGT), 32 obese subjects with normal glucose tolerance (obese-NGT), and 42 lean healthy control subjects (control-NGT). Anthropometry and blood biochemical parameters were measured and euglycemic-hyperinsulinemic clamp was performed.

RESULTS

Obese-IGT subjects were more insulin resistant in comparison with obese-NGT and control-NGT groups; obese-NGT subjects were more insulin resistant than control-NGT. Plasma sTNFR1 and sTNFR2 were markedly higher in both groups of obese subjects in comparison with control-NGT and in the obese-IGT versus obese-NGT group. Plasma sTNFR1 and sTNFR2 were inversely related to insulin sensitivity. Both relationships remained significant after adjustment for age, BMI, waist girth, percent body fat, plasma glucose, insulin, nonesterified fatty acids, cholesterol, and triglycerides. Correlation between sTNFR2 and insulin sensitivity was also present in all the groups analyzed separately, but the correlation between sTNFR1 and insulin sensitivity was present only in the obese-NGT group.

CONCLUSIONS

Our data suggest that TNF-alpha receptors are increased in obese-IGT subjects and are related to insulin resistance. These findings indicate that the TNF-alpha system might contribute to the development of insulin resistance in glucose-intolerant subjects.

Increased plasma-soluble tumor necrosis factor-alpha receptor 2 level in lean nondiabetic offspring of type 2 diabetic subjects

OBJECTIVE

Tumor necrosis factor-alpha (TNF-alpha) is one of the proposed mediators of insulin resistance, upregulated in human obesity. Insulin resistance, however, might precede the development of obesity, especially in subjects with a family history of type 2 diabetes. Therefore, the aim of the present study was to assess plasma levels of TNF-alpha and soluble forms of its receptors (soluble TNF-alpha receptors 1 [sTNFR1] and 2 [sTNFR2]) and to evaluate the relationship of the TNF-alpha system with insulin resistance in lean, nondiabetic offspring of type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

We compared 20 lean offspring (BMI <25 kg/m(2), 8 men and 12 women) of type 2 diabetic patients with 20 lean subjects with no family history of diabetes, matched for age, sex, and BMI (control group). Anthropometry and blood biochemical parameters were measured, and insulin sensitivity was evaluated with the euglycemic-hyperinsulinemic clamp technique.

RESULTS

Both men and women in the offspring group were markedly more insulin-resistant and had higher plasma levels of sTNFR2 (all P < 0.05). TNF-alpha, sTNFR1, and other examined parameters did not differ between the studied groups. Both TNF-alpha receptors were related to waist-to-hip ratio (WHR), fat-free mass (FFM), plasma total cholesterol, HDL cholesterol, LDL cholesterol, and nonesterified fatty acids (NEFAs). sTNFR2, but not sTNFR1, was also associated with insulin sensitivity (r = -0.49, P = 0.001). This relationship remained significant after adjustment for WHR, FFM, plasma insulin, and NEFA.

CONCLUSIONS

TNF-alpha system might be involved in modulating insulin action before the onset of obesity in subjects at high risk for type 2 diabetes.