Fructose alters adiponectin, haptoglobin and angiotensinogen gene expression in 3T3-L1 adipocytes

The causal impact of gut microbiota on circulating adipokine concentrations: a two-sample Mendelian randomization study

PURPOSE

Evidence from previous experimental and observational research demonstrates that the gut microbiota is related to circulating adipokine concentrations. Nevertheless, the debate as to whether gut microbiome composition causally influences circulating adipokine concentrations remains unresolved. This study aimed to take an essential step in elucidating this issue.

METHODS

We used two-sample Mendelian randomization (MR) to causally analyze genetic variation statistics for gut microbiota and four adipokines (including adiponectin, leptin, soluble leptin receptor [sOB-R], and plasminogen activator inhibitor-1 [PAI-1]) from large-scale genome-wide association studies (GWAS) datasets. A range of sensitivity analyses was also conducted to assess the stability and reliability of the results.

RESULTS

The composite results of the MR and sensitivity analyses revealed 22 significant causal associations. In particular, there is a suggestive causality between the family Clostridiaceae1 (IVW: β = 0.063, P = 0.034), the genus Butyrivibrio (IVW: β = 0.029, P = 0.031), and the family Alcaligenaceae (IVW: β=-0.070, P = 0.014) and adiponectin. Stronger causal effects with leptin were found for the genus Enterorhabdus (IVW: β=-0.073, P = 0.038) and the genus Lachnospiraceae (NK4A136 group) (IVW: β=-0.076, P = 0.01). Eight candidate bacterial groups were found to be associated with sOB-R, with the phylum Firmicutes (IVW: β = 0.235, P = 0.03) and the order Clostridiales (IVW: β = 0.267, P = 0.028) being of more interest. In addition, the genus Roseburia (IVW: β = 0.953, P = 0.022) and the order Lactobacillales (IVW: β=-0.806, P = 0.042) were suggestive of an association with PAI-1.

CONCLUSION

This study reveals a causal relationship between the gut microbiota and circulating adipokines and may help to offer novel insights into the prevention of abnormal concentrations of circulating adipokines and obesity-related diseases.

Impact of combined chronic exposure to low-dose bisphenol A and fructose on serum adipocytokines and the energy target metabolome in white adipose tissue

Background: Adipose tissue is a dynamic endocrine organ that plays a key role in regulating metabolic homeostasis. Previous studies confirmed that bisphenol A (BPA) or fructose can interfere with the function of adipose tissue. Nonetheless, knowledge on how exposure to BPA and fructose impacts energy metabolism in adipose tissue remains limited.Purpose: To determine impact of combined chronic exposure to low-dose bisphenol A and fructose on serum adipocytokines and the energy target metabolome in white adipose tissue.Method: 57 energy metabolic intermediates in adipose tissue and 7 adipocytokines in serum from Sprague Dawley rats were examined after combined exposure to two levels of BPA (lower dose: 0.25, and higher dose: 25 μg/kg every other day) and 5% fructose for 6 months.Results: combined exposure to lower-dose BPA and fructose significantly increased omentin-1, pyruvic acid, adenosine triphosphate (ATP), adenosine monophosphate (AMP), inosine monophosphate (IMP), inosine, and l-lactate; however, these parameters were not significantly affected by higher-dose BPA combined with fructose. Interestingly, the level of succinate (an intermediate of the citric acid cycle) increased dose-dependently in adipose tissue, and the level of apelin 13 (a versatile adipocytokine) decreased dose-dependently in serum after combined exposure to BPA and fructose. Phosphoenolpyruvic acid, phenyl-lactate, and ornithine were significantly correlated with asprosin, omentin-1, apelin, apelin 13, and adiponectin, while l-tyrosine was significantly correlated with irisin and a-FABP under combined exposure to BPA and fructose.Conclusions: these findings indicated that lower-dose BPA combined with fructose could amplify the impact on glycolysis, energy storage, and purine nucleotide biosynthesis in adipose tissue, and adipocytokines, such as omentin-1 and apelin 13, may be related to metabolic interference induced by BPA and fructose exposure.

Fructose Intake, Hypertension and Cardiometabolic Risk Factors in Children and Adolescents: From Pathophysiology to Clinical Aspects. A Narrative Review

Arterial hypertension, dyslipidemia, alterations in glucose metabolism and fatty liver, either alone or in association, are frequently observed in obese children and may seriously jeopardize their health. For obesity to develop, an excessive intake of energy-bearing macronutrients is required; however, ample evidence suggests that fructose may promote the development of obesity and/or metabolic alterations, independently of its energy intake. Fructose consumption is particularly high among children, because they do not have the perception, and more importantly, neither do their parents, that high fructose intake is potentially dangerous. In fact, while this sugar is erroneously viewed favorably as a natural nutrient, its excessive intake can actually cause adverse cardio-metabolic alterations. Fructose induces the release of pro-inflammatory cytokines, and reduces the production of anti-atherosclerotic cytokines, such as adiponectin. Furthermore, by interacting with hunger and satiety control systems, particularly by inducing leptin resistance, it leads to increased caloric intake. Fructose, directly or through its metabolites, promotes the development of obesity, arterial hypertension, dyslipidemia, glucose intolerance and fatty liver. This review aims to highlight the mechanisms by which the early and excessive consumption of fructose may contribute to the development of a variety of cardiometabolic risk factors in children, thus representing a potential danger to their health. It will also describe the main clinical trials performed in children and adolescents that have evaluated the clinical effects of excessive intake of fructose-containing drinks and food, with particular attention to the effects on blood pressure. Finally, we will discuss the effectiveness of measures that can be taken to reduce the intake of this sugar.

Dietary Patterns and Risk of Inflammatory Bowel Disease in Europe: Results from the EPIC Study

BACKGROUND

Specific nutrients or foods have been inconsistently associated with ulcerative colitis (UC) or Crohn's disease (CD) risks. Thus, we investigated associations between diet as a whole, as dietary patterns, and UC and CD risks.

METHODS

Within the prospective EPIC (European Prospective Investigation into Cancer) study, we set up a nested matched case-control study among 366,351 participants with inflammatory bowel disease data, including 256 incident cases of UC and 117 of CD, and 4 matched controls per case. Dietary intake was recorded at baseline from validated food frequency questionnaires. Incidence rate ratios of developing UC and CD were calculated for quintiles of the Mediterranean diet score and a posteriori dietary patterns produced by factor analysis.

RESULTS

No dietary pattern was associated with either UC or CD risks. However, when excluding cases occurring within the first 2 years after dietary assessment, there was a positive association between a "high sugar and soft drinks" pattern and UC risk (incidence rate ratios for the fifth versus first quintile, 1.68 [1.00-2.82]; Ptrend = 0.02). When considering the foods most associated with the pattern, high consumers of sugar and soft drinks were at higher UC risk only if they had low vegetables intakes.

CONCLUSIONS

A diet imbalance with high consumption of sugar and soft drinks and low consumption of vegetables was associated with UC risk. Further studies are needed to investigate whether microbiota alterations or other mechanisms mediate this association.

Catechin and quercetin attenuate adipose inflammation in fructose-fed rats and 3T3-L1 adipocytes

SCOPE

This study evaluated the capacity of dietary catechin (C), quercetin (Q), and the combination of both (CQ), to attenuate adipose inflammation triggered by high fructose (HFr) consumption in rats and by tumor necrosis factor alpha (TNF-α) in 3T3-L1 adipocytes.

METHODS AND RESULTS

In rats, HFr consumption for 6 wk caused dyslipidemia, insulin resistance, reduced plasma adiponectin, adiposity, and adipose tissue inflammation. Dietary supplementation with 20 mg/kg/day of C, Q, and CQ improved all these parameters. In 3T3-L1 adipocytes, C and Q attenuated TNF-α-induced elevated protein carbonyls, increased proinflammatory cytokine expression (MCP-1, resistin), and decreased adiponectin. The protective effects of C and Q on adipose inflammation are in part associated with their capacity to (i) decrease the activation of the mitogen-activated kinases (MAPKs) JNK and p38; and (ii) prevent the downregulation of PPAR-γ. In summary, C and Q, and to a larger extent the combination of both, attenuated adipose proinflammatory signaling cascades and regulated the balance of molecules that improve (adiponectin) or impair (TNF-α, MCP-1, resistin) insulin sensitivity.

CONCLUSION

Together, these findings suggest that dietary Q and C may have potential benefits in mitigating MetS-associated adipose inflammation, oxidative stress, and insulin resistance.

Substitution of soy protein for casein prevents oxidative modification and inflammatory response induced in rats fed high fructose diet

Fructose-rich diet is known to cause metabolic dysregulation, oxidative stress, and inflammation. We aimed to compare the effects of two dietary proteins of animal and plant origins on fructose-induced oxidative stress and inflammatory changes in liver. Wistar rats were fed either starch or fructose (60%) diet with casein or soy protein (20%) as the protein source for 8 weeks. Glucose and insulin, glycated hemoglobin and fructosamine, AOPP, and FRAP were determined in circulation. Intracellular ROS, oxidatively modified proteins (4-HNE and 3-NT adducts), adiponectin, TNF-α, IL-6 and PAI-1 mRNA expression, phosphorylation and activation of JNK and IKKβ, and NF-κB binding activity were assayed in liver. In comparison with starch fed group, fructose + casein group registered significant decline in antioxidant potential and increase in plasma glucose, insulin, and glycated proteins. Increased ROS production, 4-HNE and 3-NT modified proteins, JNK and IKKβ activation, and NF-κB binding activity were observed in them along with increased gene expression of PAI-1, IL-6, and TNF-α and decreased adiponectin expression. Substitution of soy protein for casein reduced oxidative modification and inflammatory changes in fructose-fed rats. These data suggest that soy protein but not casein can avert the adverse effects elicited by chronic consumption of fructose.

Effects of sugar-sweetened beverages on plasma acylation stimulating protein, leptin and adiponectin: relationships with metabolic outcomes

OBJECTIVE

The effects of fructose and glucose consumption on plasma acylation stimulating protein (ASP), adiponectin, and leptin concentrations relative to energy intake, body weight, adiposity, circulating triglycerides, and insulin sensitivity were determined.

DESIGN AND METHODS

Thirty two overweight/obese adults consumed glucose- or fructose-sweetened beverages (25% energy requirement) with their ad libitum diets for 8 weeks, followed by sweetened beverage consumption for 2 weeks with a standardized, energy-balanced diet. Plasma variables were measured at baseline, 2, 8, and 10 weeks, and body adiposity and insulin sensitivity at baseline and 10 weeks.

RESULTS

Fasting and postprandial ASP concentrations increased at 2 and/or 8 weeks. ASP increases correlated with changes in late-evening triglyceride concentrations. At 10 weeks, fasting adiponectin levels decreased in both groups, and decreases were inversely associated with baseline intra-abdominal fat volume. Sugar consumption increased fasting leptin concentrations; increases were associated with body weight changes. The 24-h leptin profiles increased during glucose consumption and decreased during fructose consumption. These changes correlated with changes of 24-h insulin levels.

CONCLUSIONS

The consumption of fructose and glucose beverages induced changes in plasma concentrations of ASP, adiponectin, and leptin. Further study is required to determine if these changes contribute to the metabolic dysfunction observed during fructose consumption.

Early postnatal overnutrition increases adipose tissue accrual in response to a sucrose-enriched diet

Both overnutrition and an incorrect nutrient balance have contributed to the rise in obesity. Moreover, it is now clear that poor nutrition during early life augments the possibility of excess weight gain in later years. Our aim was to determine how neonatal overnutrition affects later responses to a sucrose-enriched diet and whether this varies depending upon when the diet is introduced in postnatal life. Male Wistar rats raised in litters of four or 12 pups were given a 33% sucrose solution instead of water from weaning (day 21) or postnatal day (PND) 65. All rats received normal chow ad libitum until they were euthanized on PND 80. Body weight (BW) and food and liquid intake were monitored throughout the study. Fat mass, adipocyte morphology, serum biochemical and hormonal parameters, and hypothalamic neuropeptide mRNA levels were measured at study termination. Neonatal overnutrition increased food intake, BW, and leptin levels, induced adipocyte hypertrophy, and decreased total ghrelin levels. The sucrose-enriched diet increased total energy intake, adipose accrual, and leptin, adiponectin, and acylated ghrelin levels but decreased BW. Most of these responses were accentuated in neonatally overnourished rats, which also had increased insulin and triglyceride levels. However, long-term sucrose intake induced adipocyte hypertrophy in rats from normal-sized litters but not in neonatally overfed rats. The results reported here indicate that neonatal overnutrition increases the detrimental response to a diet rich in sucrose later in life. Moreover, the timing and duration of the exposure to a sucrose-enriched diet alter the adverse metabolic outcomes.

Nutritional and hormonal modulation of adiponectin and its receptors adipoR1 and adipoR2

Adiponectin is the most abundant plasma protein synthesized mostly by adipose tissue and is an insulin-sensitive hormone, playing a central role in glucose and lipid metabolism. Adiponectin effects are mediated via two receptors, adipoR1 and adipoR2. Several hormones and diet components that are involved in insulin resistance may impair insulin sensitivity at least in part by decreasing adiponectin and adiponectin receptors. Adiponectin expression and serum levels are associated with the amount and type of fatty acids and carbohydrate consumed. Other food items, such as vitamins, alcohol, sodium, green tea, and coffee, have been reported to modify adiponectin levels. Several hormones, including testosterone, estrogen, prolactin, glucocorticoids, catecholamines, and growth hormone, have been shown to inhibit adiponectin production, but the studies are still controversial. Even so, adiponectin is a potential therapeutic target in the treatment of diabetes mellitus and other diseases associated with hypoadiponectinemia.