Derek K. Hagman

Gene expression changes in adipose tissue with diet- and/or exercise-induced weight loss

Adipose tissue plays a role in obesity-related cancers via increased production of inflammatory factors, steroid hormones, and altered adipokines. The impact of weight loss on adipose tissue gene expression may provide insights into pathways linking obesity with cancer risk. We conducted an ancillary study within a randomized trial of diet, exercise, or combined diet + exercise versus control among overweight/obese postmenopausal women. In 45 women, subcutaneous adipose tissue biopsies were conducted at baseline and after 6 months, and changes in adipose tissue gene expression were determined by microarray with an emphasis on prespecified candidate pathways as well as by unsupervised clustering of more than 37,000 transcripts (Illumina). Analyses were conducted first by randomization group and then by degree of weight change at 6-months in all women combined. At 6 months, diet, exercise, and diet + exercise participants lost a mean of 8.8, 2.5, and 7.9 kg (all P < 0.05 vs. no change in controls). There was no significant change in candidate gene expression by intervention group. In analysis by weight change category, greater weight loss was associated a decrease in 17β-hydroxysteroid dehydrogenase-1 (HSD17B1, Ptrend < 0.01) and leptin (LEP, Ptrend < 0.01) expression, and marginally significant increased expression of estrogen receptor-1 (ESR1, Ptrend = 0.08) and insulin-like growth factor–binding protein-3 (IGFBP3, Ptrend = 0.08). Unsupervised clustering revealed 83 transcripts with statistically significant changes. Multiple gene expression changes correlated with changes in associated serum biomarkers. Weight loss was associated with changes in adipose tissue gene expression after 6 months, particularly in two pathways postulated to link obesity and cancer, that is, steroid hormone metabolism and IGF signaling. Cancer Prev Res; 6(3); 217–31. ©2013 AACR.

Macrophage Metalloelastase (MMP12) Regulates Adipose Tissue Expansion, Insulin Sensitivity, and Expression of Inducible Nitric Oxide Synthase

Macrophage metalloelastase, a matrix metallopeptidase (MMP12) predominantly expressed by mature tissue macrophages, is implicated in pathological processes. However, physiological functions for MMP12 have not been described. Because mRNA levels for the enzyme increase markedly in adipose tissue of obese mice, we investigated the role of MMP12 in adipose tissue expansion and insulin resistance. In humans, MMP12 expression correlated positively and significantly with insulin resistance, TNF-α expression, and the number of CD14(+)CD206(+) macrophages in adipose tissue. MMP12 was the most abundant matrix metallopeptidase detected by proteomic analysis of conditioned medium of M2 macrophages and dendritic cells. In contrast, it was detected only at low levels in bone marrow derived macrophages and M1 macrophages. When mice received a high-fat diet, adipose tissue mass increased and CD11b(+)F4/80(+)CD11c(-) macrophages accumulated to a greater extent in MMP12-deficient (Mmp12(-/-)) mice than in wild-type mice (Mmp12(+/+)). Despite being markedly more obese, fat-fed Mmp12(-/-) mice were more insulin sensitive than fat-fed Mmp12(+/+) mice. Expression of inducible nitric oxide synthase (Nos2) by Mmp12(-/-) macrophages was significantly impaired both in vivo and in vitro, suggesting that MMP12 might mediate nitric oxide production during inflammation. We propose that MMP12 acts as a double-edged sword by promoting insulin resistance while combatting adipose tissue expansion.

n3 PUFAs Do Not Affect Adipose Tissue Inflammation in Overweight to Moderately Obese Men and Women

Recent studies have indicated that omega-3 (n3) polyunsaturated fatty acids (PUFAs) decrease adipose tissue inflammation in rodents and in morbidly obese humans. We investigated whether a diet rich in n3 PUFAs from both marine and plant sources reduces adipose tissue and systemic inflammation in overweight to moderately obese adults. We conducted a randomized, single-blind, parallel-design, placebo-controlled feeding trial. Healthy men and women with a body mass index between 28 and 33 kg/m(2) consumed a diet rich in n3 PUFAs (3.5% of energy intake; n = 11) from plant and marine sources or a control diet (0.5% of energy intake from n3 PUFAs; n = 13). These diets were consumed for 14 wk (ad libitum for 12 wk). All foods were provided for the entire study period. Subcutaneous abdominal adipose tissue and fasting plasma were collected after the first 2 wk with the control diet and again at the end of the 14-wk dietary period. The primary outcome of this ex post analysis was the adipose tissue gene expression of 13 key mediators of inflammation. Adipose tissue gene expression of inflammatory mediators did not differ between the 2 groups, after adjustment for weight change. Furthermore, none of the 5 plasma markers of systemic inflammation differed significantly as an effect of diet treatment. We conclude that a relatively high dose of n3 PUFAs from plant and marine sources did not significantly lower adipose tissue or systemic inflammation in overweight to moderately obese healthy men and women over 14 wk.

Improvements in glycemic control after gastric bypass occur despite persistent adipose tissue inflammation

Type 2 diabetes commonly goes into remission following Roux‐en‐Y gastric bypass (RYGB). As the mechanisms remain incompletely understood, a reduction in adipose tissue inflammation may contribute to these metabolic improvements. Therefore, whether RYGB reduces adipose tissue inflammation compared with equivalent weight loss from an intensive lifestyle intervention was investigated.

The short-term and long-term effects of bariatric/metabolic surgery on subcutaneous adipose tissue inflammation in humans

CONTEXT The mechanisms mediating the short- and long-term improvements in glucose homeostasis following bariatric/metabolic surgery remain incompletely understood. OBJECTIVE To investigate whether a reduction in adipose tissue inflammation plays a role in the metabolic improvements seen after bariatric/metabolic surgery, both in the short-term and longer-term. DESIGN Fasting blood and subcutaneous abdominal adipose tissue were obtained before (n=14), at one month (n=9), and 6-12months (n=14) after bariatric/metabolic surgery from individuals with obesity who were not on insulin or anti-diabetes medication. Adipose tissue inflammation was assessed by a combination of whole-tissue gene expression and flow cytometry-based quantification of tissue leukocytes. RESULTS One month after surgery, body weight was reduced by 13.5±4.4kg (p<0.001), with improvements in glucose tolerance reflected by a decrease in area-under-the-curve (AUC) glucose in 3-h oral glucose tolerance tests (-105±98mmol/L * min; p=0.009) and enhanced pancreatic β-cell function (insulinogenic index: +0.8±0.9pmol/mmol; p=0.032), but no change in estimated insulin sensitivity (Matsuda insulin sensitivity index [ISI]; p=0.720). Furthermore, although biomarkers of systemic inflammation and pro-inflammatory gene expression in adipose tissue remained unchanged, the number of neutrophils increased in adipose tissue 15-20 fold (p<0.001), with less substantial increases in other leukocyte populations. By the 6-12month follow-up visit, body weight was reduced by 34.8±10.8kg (p<0.001) relative to baseline, and glucose tolerance was further improved (AUC glucose -276±229; p<0.001) along with estimated insulin sensitivity (Matsuda ISI: +4.6±3.2; p<0.001). In addition, improvements in systemic inflammation were reflected by reductions in circulating C-reactive protein (CRP; -2.0±5.3mg/dL; p=0.002), and increased serum adiponectin (+1358±1406pg/mL; p=0.003). However, leukocyte infiltration of adipose tissue remained elevated relative to baseline, with pro-inflammatory cytokine mRNA expression unchanged, while adiponectin mRNA expression trended downward (p=0.069). CONCLUSION Both the short- and longer-term metabolic improvements following bariatric/metabolic surgery occur without significant reductions in measures of adipose tissue inflammation, as assessed by measuring the expression of genes encoding key mediators of inflammation and by flow cytometric immunophenotyping and quantification of adipose tissue leukocytes.

No difference in ad libitum energy intake in healthy men and women consuming beverages sweetened with fructose, glucose, or high-fructose corn syrup: a randomized trial

BACKGROUND Increased energy intake is consistently observed in individuals consuming sugar-sweetened beverages (SSBs), likely mainly because of an inadequate satiety response to liquid calories. However, SSBs have a high content of fructose, the consumption of which acutely fails to trigger responses in key signals involved in energy homeostasis. It is unclear whether the fructose content of SSBs contributes to the increased energy intake in individuals drinking SSBs. OBJECTIVE We investigated whether the relative amounts of fructose and glucose in SSBs modifies ad libitum energy intake over 8 d in healthy adults without fructose malabsorption. DESIGN We conducted 2 randomized, controlled, double-blind crossover studies to compare the effects of consuming 4 servings/d of a fructose-, glucose-, or aspartame-sweetened beverage (study A; n = 9) or a fructose-, glucose-, or high-fructose corn syrup (HFCS)-sweetened beverage (study B; n = 24) for 8 d on overall energy intake. SSBs were provided at 25% of estimated energy requirement, or an equivalent volume of the aspartame-sweetened beverage, and consumption was mandatory. All solid foods were provided at 125% of estimated energy requirements and were consumed ad libitum. RESULTS In study A, ad libitum energy intake was 120% ± 10%, 117% ± 12%, and 102% ± 15% of estimated energy requirements when subjects consumed the fructose-, glucose-, and aspartame-sweetened beverages. Energy intake was significantly higher in the fructose and glucose phases than in the aspartame phase (P < 0.003 for each), with no difference between the fructose and glucose phases (P = 0.462). In study B, total energy intake during the fructose, HFCS, and glucose phases was 116% ± 14%, 116% ± 16%, and 116% ± 16% of the subjects estimated total energy requirements (P = 0.880). CONCLUSIONS In healthy adults, total 8-d ad libitum energy intake was increased in individuals consuming SSBs compared with aspartame-sweetened beverages. The energy overconsumption observed in individuals consuming SSBs occurred independently of the relative amounts of fructose and glucose in the beverages. These trials were registered at clinicaltrials.gov as NCT00475475 and NCT01424306.

No differential effect of beverages sweetened with fructose, high-fructose corn syrup, or glucose on systemic or adipose tissue inflammation in normal-weight to obese adults: a randomized controlled trial

BACKGROUND Sugar-sweetened beverage (SSB) consumption and low-grade chronic inflammation are both independently associated with type 2 diabetes and cardiovascular disease. Fructose, a major component of SSBs, may acutely trigger inflammation, which may be one link between SSB consumption and cardiometabolic disease. OBJECTIVE We sought to determine whether beverages sweetened with fructose, high-fructose corn syrup (HFCS), and glucose differentially influence systemic inflammation [fasting plasma C-reactive protein and interleukin-6 (IL-6) as primary endpoints] acutely and before major changes in body weight. Secondary endpoints included adipose tissue inflammation, intestinal permeability, and plasma fetuin-A as potential mechanistic links between fructose intake and low-grade inflammation. DESIGN We conducted a randomized, controlled, double-blind, crossover design dietary intervention (the Diet and Systemic Inflammation Study) in 24 normal-weight to obese adults without fructose malabsorption. Participants drank 4 servings/d of fructose-, glucose-, or HFCS-sweetened beverages accounting for 25% of estimated calorie requirements while consuming a standardized diet ad libitum for three 8-d periods. RESULTS Subjects consumed 116% of their estimated calorie requirement while drinking the beverages with no difference in total energy intake or body weight between groups as reported previously. Fasting plasma concentrations of C-reactive protein and IL-6 did not differ significantly at the end of the 3 diet periods. We did not detect a consistent differential effect of the diets on measures of adipose tissue inflammation except for adiponectin gene expression in adipose tissue (P = 0.005), which was lowest after the glucose phase. We also did not detect consistent evidence of a differential impact of these sugars on measures of intestinal permeability (lactulose:mannitol test, plasma zonulin, and plasma lipopolysaccharide-binding protein). CONCLUSION Excessive amounts of fructose, HFCS, and glucose from SSBs consumed over 8 d did not differentially affect low-grade chronic systemic inflammation in normal-weight to obese adults. This trial was registered at clinicaltrials.gov as NCT01424306.

Circulating sex steroids coregulate adipose tissue immune cell populations in healthy men

Male hypogonadism results in changes in body composition characterized by increases in fat mass. Resident immune cells influence energy metabolism in adipose tissue and could promote increased adiposity through paracrine effects. We hypothesized that manipulation of circulating sex steroid levels in healthy men would alter adipose tissue immune cell populations. Subjects (n = 44 men, 19-55 yr of age) received 4 wk of treatment with the gonadotropin-releasing hormone receptor antagonist acyline with daily administration of 1) placebo gel, 2) 1.25 g testosterone gel (1.62%), 3) 5 g testosterone gel, or 4) 5 g testosterone gel with an aromatase inhibitor. Subcutaneous adipose tissue biopsies were performed at baseline and end-of-treatment, and adipose tissue immune cells, gene expression, and intra-adipose estrogen levels were quantified. Change in serum total testosterone level correlated inversely with change in the number of CD3+ (β = -0.36, P = 0.04), CD4+ (β = -0.34, P = 0.04), and CD8+ (β = -0.33, P = 0.05) T cells within adipose tissue. Change in serum 17β-estradiol level correlated inversely with change in the number of adipose tissue macrophages (ATMs) (β = -0.34, P = 0.05). A negative association also was found between change in serum testosterone and change in CD11c+ ATMs (β = -0.41, P = 0.01). Overall, sex steroid deprivation was associated with increases in adipose tissue T cells and ATMs. No associations were found between changes in serum sex steroid levels and changes in adipose tissue gene expression. Circulating sex steroid levels may regulate adipose tissue immune cell populations. These exploratory findings highlight a possible novel mechanism that could contribute to increased metabolic risk in hypogonadal men.

Consuming glucose-sweetened, not fructose-sweetened, beverages increases fasting insulin in healthy humans

Fructose-, compared to glucose-, sweetened beverages increase liver triglyceride content in the short-term, prior to weight gain. In secondary analyses of a randomized cross-over design study during which 24 healthy adults consumed 25% of their estimated energy requirement in the form of glucose-, fructose-, and high-fructose corn syrup-sweetened beverages in addition to an identical ad libitum diet for three periods of 8 days each, we investigated the hypothesis that fructose in sweetened beverages also triggers insulin resistance in the short term. Total energy intake, body weight, and fasting glucose did not differ among diet phases. However, there was a significant trend for higher fasting insulin (p = 0.042 for trend) and, among normal-weight participants, homeostasis model assessment index of insulin resistance (p = 0.034 for diet × adiposity interaction) according to the glucose content of the beverages. In conclusion, in contrast to our hypothesis, insulin resistance was increased with higher glucose vs. fructose content of the beverages in this short-term trial.

Abstract 3559: Gene-expression changes in adipose tissue with diet- and/or exercise-induced weight loss: a randomized controlled trial

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Background: Adipose tissue (AT) plays a role in obesity-related disease pathogenesis via increased production of inflammatory factors, steroid hormones, and altered lipid metabolism. The impact of diet and/or exercise induced weight loss on AT gene expression will provide key insights into the pathways linking obesity with metabolic disease. Methods: We conducted an ancillary study within a randomized trial of calorie-reduced diet (D), exercise (E), or combined diet and exercise (D+E) vs control among overweight/obese postmenopausal women (Nutrition and Exercise for Women Study). Subcutaneous AT was biopsied at baseline and 6 months from 47 women. Gene expression was measured by the Illumina BeadChip WG-6 and interrogated for changes in candidate genes, and all array-based genes. Analyses were conducted by intervention group and by weight-loss group. Results: Participants were aged 58.3±4.7 years; with a mean BMI of 31.1±4.3 kg/m2. At 6 month, controls were weight-stable while D, E, and D+E participants lost on average 8.8 kg, 2.5 kg, and 7.9 kg (all P 10% weight loss there was a progressive decrease in 17α hydroxysteroid dehydrogenase-1 (-35% p-trend=0.0002), steroid sulfatase (-26%, p-trend=0.02), 17α hydroxysteroid dehydrogenase-10 (-5%, p-trend=0.045), intercellular adhesion molecule 4 (-9%, p-trend=0.01), serum amyloid A (-38%, p-trend=0.01), and leptin (-44%, p-trend=0.00003) expression, with trends towards increased expression of estrogen receptor-1 (24% p-trend=0.004), C-reactive protein (23%, p-trend 0.008), vascular cell adhesion molecule 1 (34%, p-trend=0.04) and insulin-like growth factor (IGF) binding protein-3 (37%; p-trend=0.003). The unsupervised clustering of >37.000 transcripts by weight loss revealed 78 transcripts with statistically significant adjusted p-values. Leptin, the strongest signal in our candidate-gene analysis, was the 33rd strongest hit in this clustering. Conclusions: A 6-month lifestyle intervention caused weight loss with corresponding changes in AT gene expression, particularly steroid-hormone metabolism and IGF signaling, both pathways postulated to link obesity and cancer. Leptin is a primary signaling target of weight loss in adipose tissue, but weight change altered also a number of other biologic pathways in adipose tissue which requires further investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3559. doi:1538-7445.AM2012-3559