Faculty Bibliography

BACKGROUND: Obesity, metabolic syndrome (MS) and dyslipidemia are independent risk factors for cardiovascular disease. Bariatric surgery is increasingly recognized as an effective intervention for improving each of these risk factors. There are sparse data on the long-term durability of metabolic changes associated with bariatric surgery, in particular with laparoscopic gastric banding (LGB). Our objective was to evaluate the durability of metabolic changes associated with LGB in nonmorbid obesity. METHODS: Fifty obese patients (BMI 30-40) with >/=1 obesity-related comorbidity were prospectively followed for five years. At follow-up, subjects underwent fasting blood measures, including lipid NMR spectroscopy and standard lipid profile. RESULTS: Forty-seven patients (45 female, mean age 43.8 years) completed four years follow-up (46 completed five years). Baseline BMI was 35.1 +/- 2.6. Subjects exhibited mean weight loss of 22.3 +/- 7.9 kg (22.9 +/- 7.4%) at year one and maintained this (19.8 +/- 10.2%) over five years. At baseline, 43% (20/47) of subjects met criteria for MS. This was reduced to 15% (7/47) at year one and remained reduced over five years (13%, 6/46) (p < 0.001). There were reductions in triglycerides (p < 0.001) and increases in HDL cholesterol (HDL-C, p < 0.001) and HDL particle concentration (p = 0.02), with a trend toward increased HDL particle size (p = 0.06) at year five. Changes in triglycerides and HDL-C were more prominent in patients with MS at baseline, but unassociated with weight loss or waist circumference. Changes in HDL particle size and concentration were not associated with MS status, weight loss, waist circumference, or statin use. CONCLUSIONS: LGB produces significant weight loss, resolution of MS and changes in lipid profile suggestive of beneficial HDL remodeling. These changes persist five years following LGB.

Background: While fruit and vegetable (F&V) consumption is associated with reduced risk of stroke and coronary heart disease, there is little data on peripheral artery disease (PAD). We sought to study the association between F&V intake and prevalence of PAD in a large community cohort. Methods: From 2003 - 2008, over 3.5 million self-referred participants at >20,000 US sites completed a medical and lifestyle questionnaire and were evaluated by screening ankle-brachial index <0.9 for PAD. Subjects were queried for frequency of consumption of >3 servings of F&V (<1x/mo, 1x/mo- 1x/wk, 2-3x/wk, 4- 5x/wk, daily). Multivariate logistic regression analysis was used to estimate odds of PAD by F&V intake. Results: Among 3,523,545 individuals, mean age was 63.4 + 10.6 years and 63% were female. F&V intake ranged from 7% (<1x/month) to 29% (daily consumption of >3 servings). After adjustment for age, sex, race, smoking, physical activity, diabetes, hypertension, hyperlipidemia and family history of vascular disease, there was a step-wise inverse association of F&V intake with PAD (P for trend <0.0001; Figure). Compared to subjects with <1x/month consumption of >3 servings of F&V, daily intake was associated with 20% lower odds of PAD (OR 0.800, 95% CI 0.784 - 0.816). Conclusion: We present data from a large community cohort, in which F&V intake exhibited an inverse step-wise relationship with PAD prevalence after correction for multiple established risk factors, suggestive of protective effects in this vascular territory. (Figure Presented)

BACKGROUND: Chronic inflammation may contribute to insulin resistance (IR), metabolic syndrome and atherosclerosis although evidence of causality is lacking in humans. We hypothesized that very low-dose experimental endotoxemia would induce adipose tissue inflammation and systemic IR during a low-grade but asymptomatic inflammatory response and thus provide an experimental model for future tests of pharmacologic and genomic modulation of cardio-metabolic traits in humans. METHODS: Ten healthy, human volunteers (50% male, 90% Caucasian, mean age 22.7 +/- 3.8) were randomized in a double-masked, placebo-controlled, crossover study to separate 36-hour inpatient visits (placebo versus intravenous-LPS 0.6 ng/kg). We measured clinical symptoms via the McGill pain questionnaire and serial vital signs. Plasma and serum were collected for measurement of cytokines, C-reactive protein, insulin and glucose, serial whole blood & subcutaneous adipose tissue mRNA expression were measured by real-time PCR. HOMA-IR, a well-validated measure of IR was calculated to estimate insulin resistance, and frequently sampled intravenous glucose tolerance testing (FSIGTT) was performed to confirm an insulin resistant state. We performed ANOVA and within subject ANOVA to understand the differences in cytokines, adipose tissue inflammation and IR before and after LPS or placebo. RESULTS: There was no significant difference between placebo and LPS in clinical responses of symptom scores, body temperature or heart rate. However, low-dose endotoxemia induced a rapid and transient 25-fold induction of plasma TNF-alpha and 100-fold increase in plasma IL-6 (Figure 1B) (p < 0.001 for both) both peaking at two hours, followed by modest inflammation in adipose tissue with increases in mRNA levels of several inflammatory genes known to modulate adipose and systemic insulin resistance. Adipose tissue mRNA levels of IL-6 (peak 6-fold, ANOVA F = 27.5, p < 0.001) and TNF-alpha (peak 1.8-fold, F = 2.9, p = 0.01) increased with MCP-1 (peak 10-fold, F = 5.6, p < 0.01) and fractalkine (CX3CL1) (peak 15-fold, F = 13.3, p < 0.001). Finally, HOMA-IR was 32% higher following LPS compared to placebo (p < 0.01) and insulin sensitivity declined by 21% following LPS compared to placebo (p < 0.05). CONCLUSIONS: We present a low dose human endotoxemia model of inflammation which induces adipose tissue inflammation and systemic insulin resistance in the absence of overt clinical response. Such a model has the potential for broad and safe application in the study of novel therapeutics and genomic influences in cardio-metabolic disease.

Elevated plasma fibrinogen is a prothrombotic risk factor for cardiovascular disease (CVD). Recent small studies report that fibrinogen oxidative modifications, specifically tyrosine residue nitration, can occur in inflammatory states and may modify fibrinogen function. HDL cholesterol is inversely related to CVD and suggested to reduce the oxidation of LDL cholesterol, but whether these antioxidant functions extend to fibrinogen modifications is unknown. We used a recently validated ELISA to quantify nitrated fibrinogen during experimental human endotoxemia (N=23) and in a cohort of healthy adults (N=361) who were characterized for inflammatory and HDL parameters as well as subclinical atherosclerosis measures, carotid artery intima-medial thickness (IMT) and coronary artery calcification (CAC). Fibrinogen nitration increased following endotoxemia and directly correlated with accelerated ex vivo plasma clotting velocity. In the observational cohort, nitrated fibrinogen was associated with levels of CRP and serum amyloid A. Nitrated fibrinogen levels were not lower with increasing HDL cholesterol and did not associate with IMT and CAC. In humans, fibrinogen nitration was induced during inflammation and was correlated with markers of inflammation and clotting function but not HDL cholesterol or subclinical atherosclerosis in our modest sample. Inflammation-induced fibrinogen nitration may be a risk factor for promoting CVD events.