Acute intake of a high-fructose diet alters the balance of adipokine concentrations and induces neutrophil influx in the liver

Free sugar intake is associated with reduced proportion of circulating invariant natural killer T cells among women experiencing overweight and obesity

Background

Higher prevalence of obesity has been observed among women compared to men, which can be explained partly by the higher consumption of sweets and physical inactivity. Obesity can alter immune cell infiltration, and therefore increase the susceptibility to develop chronic inflammation and metabolic disorders. In this study, we aimed to explore the association between free sugar intake and other unhealthy lifestyle habits in relation to the proportion of circulating iNKT cells among women with healthy weight and women experiencing overweight and obesity.

Methods

A cross-sectional study was conducted on 51 Saudi women > 18 years, wherein their daily free sugar intake was assessed using the validated Food Frequency Questionnaire. Data on smoking status, physical activity, and supplement use were also collected. Anthropometric data including height, weight, waist circumference were objectively measured from each participants. The proportion of circulating iNKT cells was determined using flow cytometry.

Results

Smoking, physical activity, supplement use, and weight status were not associated with proportion of circulating iNKT cells. Significant association was found between proportion of circulating iNKT cells and total free sugar intake and free sugar intake coming from solid food sources only among women experiencing overweight and obesity (Beta: -0.10: Standard Error: 0.04 [95% Confidence Interval: -0.18 to -0.01], p= 0.034) and (Beta: -0.15: Standard Error: 0.05 [95% Confidence Interval: -0.25 to -0.05], p= 0.005), respectively.

Conclusion

Excessive free sugar consumption may alter iNKT cells and consequently increase the risk for chronic inflammation and metabolic disorders.

The Impact of Excessive Fructose Intake on Adipose Tissue and the Development of Childhood Obesity

Worldwide, childhood obesity cases continue to rise, and its prevalence is known to increase the risk of non-communicable diseases typically found in adults, such as cardiovascular disease and type 2 diabetes mellitus. Thus, comprehending its multiple causes to build healthier approaches and revert this scenario is urgent. Obesity development is strongly associated with high fructose intake since the excessive consumption of this highly lipogenic sugar leads to white fat accumulation and causes white adipose tissue (WAT) inflammation, oxidative stress, and dysregulated adipokine release. Unfortunately, the global consumption of fructose has increased dramatically in recent years, which is associated with the fact that fructose is not always evident to consumers, as it is commonly added as a sweetener in food and sugar-sweetened beverages (SSB). Therefore, here, we discuss the impact of excessive fructose intake on adipose tissue biology, its contribution to childhood obesity, and current strategies for reducing high fructose and/or free sugar intake. To achieve such reductions, we conclude that it is important that the population has access to reliable information about food ingredients via food labels. Consumers also need scientific education to understand potential health risks to themselves and their children.

Associations of ultra-processed food consumption, circulating protein biomarkers, and risk of cardiovascular disease

BACKGROUND

We aim to examine the association between ultra-processed foods (UPF) consumption and cardiovascular disease (CVD) risk and to identify plasma proteins associated with UPF.

METHODS

This prospective cohort study included 26,369 participants from the Swedish Malmö Diet and Cancer Study, established in 1991-1996. Dietary intake was assessed using a modified diet history method, and UPF consumption was estimated using the NOVA classification system. A total of 88 selected CVD-related proteins were measured among 4475 subjects. Incident CVD (coronary heart disease and ischemic stroke) was defined as a hospital admission or death through registers. Cox proportional hazards regression models were performed to analyze the associations of UPF intake with risks of CVD. Linear regression models were used to identify the plasma proteins associated with UPF intake.

RESULTS

During 24.6 years of median follow-up, 6236 participants developed CVD, of whom 3566 developed coronary heart disease and 3272 developed ischemic stroke. The adjusted hazard ratio (95% confidence interval) in the 4th versus 1st quartile of UPF was 1.18 (1.08, 1.29) for CVD, 1.20 (1.07, 1.35) for coronary heart disease, and 1.17 (1.03, 1.32) for ischemic stroke. Plasma proteins interleukin 18, tumor necrosis factor receptor 2, macrophage colony-stimulating factor 1, thrombomodulin, tumor necrosis factor receptor 1, hepatocyte growth factor, stem cell factor, resistin, C-C motif chemokine 3, and endothelial cell-specific molecule 1 were positively associated with UPF after correcting for multiple testing.

CONCLUSIONS

Our study showed that high UPF intake increased the risk of CVD and was associated with several protein biomarkers. Future studies are warranted to validate these findings and assess the potential pathways between UPF intake and CVD.

Acute exercise modulates the inflammatory response in adipose tissue in both lean and obese mice

OBJECTIVES

Acute physical exercise acts as a metabolic stressor, promoting activation of the immune system, and this response could be relevant in the adipose tissue remodeling process. In addition, some cytokines have important functions in lipolysis. Because chronic exercise improves obesity-related metabolic and inflammatory dysfunction, herein we investigated the effect of acute exercise on the inflammatory responses in the adipose tissues of lean and obese mice.

METHODS

Lean mice were fed a standard chow diet, whereas obese mice were fed a high-refined carbohydrate diet for 8 wk. Both groups were subjected to 60 min of moderate-intensity exercise.

RESULTS

In the epididymal adipose tissue of lean mice, exercise enhanced interleukin (IL)-6 and tumor necrosis factor-α levels, which correlated positively with increased serum free fatty acid concentrations. In vivo confocal imaging of epididymal adipose tissue vessels revealed higher recruitment of neutrophils after exercise. Also, the number of leukocytes expressing CD11b+F480- was elevated 6 h after exercise. Similarly, the chemokine (C-X-C motif) ligand 1 level increased at 6 h and remained high until 24 h after exercise. Myeloperoxidase activity was increased at 6, 12, and 24 h after exercise. Surprisingly, however, no changes were observed in epididymal adipose tissue from obese mice, considering proinflammatory cytokines (IL-6 and tumor necrosis factor-α). On the other hand, IL-13, IL-4, and IL-10 levels were higher in obese mice after exercise.

CONCLUSIONS

These data suggest that acute exercise promotes an inflammatory response in the adipose tissue of lean mice that is observed as part of its role in adipose tissue remodeling. In contrast, acute exercise promotes an antiinflammatory response in adipose tissue from obese mice, likely as an important tool for restoring homeostasis.

Sweetener System Intervention Shifted Neutrophils from Homeostasis to Priming

BACKGROUND

Non-nutritive sweeteners (NNS) are part of personalized nutrition strategies supporting healthy glycemic control. In contrast, the consumption of non-nutritive sweeteners has been related to person-specific and microbiome-dependent glycemic impairments. Reports on the effects of NNS on our highly individual cellular immune system are sparse. The recent identification of taste receptor expression in a variety of immune cells, however, suggested their immune-modulatory relevance.

METHODS

We studied the influence of a beverage-typical NNS system on the transcriptional profiling of sweetener-cognate taste receptors, selected cytokines and their receptors, and on Ca²⁺ signaling in isolated blood neutrophils. We determined plasma concentrations of saccharin, acesulfame-K, and cyclamate by HPLC-MS/MS, upon ingestion of a soft drink-typical sweetener surrogate. In an open-labeled, randomized intervention study, we determined pre- versus post-intervention transcript levels by RT-qPCR of sweetener-cognate taste receptors and immune factors.

RESULTS

Here we show that the consumption of a food-typical sweetener system modulated the gene expression of cognate taste receptors and induced the transcriptional regulation signatures of early homeostasis- and late receptor/signaling- and inflammation-related genes in blood neutrophils, shifting their transcriptional profile from homeostasis to priming. Notably, sweeteners at postprandial plasma concentrations facilitated fMLF (N-formyl-Met-Leu-Phe)-induced Ca²⁺ signaling.

CONCLUSIONS

Our results support the notion of sweeteners priming neutrophils to higher alertness towards their adequate stimuli.

Association between Sugar-Sweetened Beverage Consumption and Executive Function in Children

The association between sugar-sweetened beverages (SSB) and executive function among children has been less investigated. We aimed to explore this topic. We randomly recruited 6387 children aged 6-12 years from five elementary schools in Guangzhou, China in 2019. Information on frequency and servings of children's SSB consumption was assessed using a questionnaire. Children's executive function was evaluated using parents' ratings of the Behavioral Rating Inventory of Executive Function (BRIEF), which comprises eight subscales-including inhibit, shift, emotional control, initiate, working memory, plan/organize, organization of materials and monitor, as well as three composite indexes including behavioral regulation index (BRI), metacognition index (MI), and global executive index (GEC). SSB consumption was positively associated with all subscales and composite scores of BRIEF as well as higher risks of elevated executive difficulties, indicating poorer executive function. For example, children who drank SSB ≥2 times/week were related to higher scores of GEC (estimates, 95% confidence interval (CI): 2.44, 1.79 to 3.09) compared with those who never drank SSB. The odds ratio of elevated GEC associated with SSB consumption ≥2 times/week was 1.62 (95% CI: 1.34, 1.96) than non-consumers. The results of this study indicated that SSB consumption was associated with poorer executive function in children.

TNAP: A New Multitask Enzyme in Energy Metabolism

Tissue-nonspecific alkaline phosphatase (TNAP) is mainly known for its necessary role in skeletal and dental mineralization, which relies on the hydrolysis of the mineralization inhibitor inorganic pyrophosphate (PP_i). Mutations in the gene encoding TNAP leading to severe hypophosphatasia result in strongly reduced mineralization and perinatal death. Fortunately, the relatively recent development of a recombinant TNAP with a bone anchor has allowed to correct the bone defects and prolong the life of affected babies and children. Researches on TNAP must however not be slowed down, because accumulating evidence indicates that TNAP activation in individuals with metabolic syndrome (MetS) is associated with enhanced cardiovascular mortality, presumably in relation with cardiovascular calcification. On the other hand, TNAP appears to be necessary to prevent the development of steatohepatitis in mice, suggesting that TNAP plays protective roles. The aim of the present review is to highlight the known or suspected functions of TNAP in energy metabolism that may be associated with the development of MetS. The location of TNAP in liver and its function in bile excretion, lipopolysaccharide (LPS) detoxification and fatty acid transport will be presented. The expression and function of TNAP in adipocyte differentiation and thermogenesis will also be discussed. Given that TNAP is a tissue- and substrate-nonspecific phosphatase, we believe that it exerts several crucial pathophysiological functions that are just beginning to be discovered.

Metabolic and Appetite Effects of Fructose and Glucose in Subjects with Type 1 Diabetes: A Randomized Crossover Clinical Trial

BACKGROUND

Fructose has been widely used for producing lower post-infusion glucose increase than other carbohydrates, but it seems that it promotes an increase in post-infusion triglycerides.

OBJECTIVE

The present study investigated the effects of fructose and glucose in metabolic variables and appetite sensations in patients with type 1 diabetes mellitus (T1DM).

METHODS

This is a single-blind, randomized, and crossover study (washout of 1-5 weeks), which evaluated 16 adult T1DM patients, accompanied at University Hospital. After eight hours of overnight fasting, there was an assessment of capillary blood glucose, anthropometric variables, appetite sensations, and laboratory tests (glycemia, lipemia, leptin and glucagon) were conducted. Subsequently, they received 200mL of solutions with water and 75g of crystal fructose or glucose. Appetite sensations and capillary blood glucose were evaluated in different post-infusion times. Blood was drawn after 180 minutes for the laboratory tests.

RESULTS

Blood glucose increased after the intake of both solutions, but glucose induced a higher elevation. None of them increased triglycerides or glucagon. Glucagon maintenance was similar among the solutions. Furthermore, both solutions reduced leptin and increased fullness, but only fructose increased the lack of interest in eating sweets.

CONCLUSION

Fructose induced a smaller increase in postprandial blood glucose than glucose, without changes in triglycerides and glucagon. In addition, leptin levels and appetite sensations were similar to glucose. Other studies are needed in order to confirm these findings, especially in the long term, so that their use becomes really reliable.

Associations of maternal fructose and sugar-sweetened beverage and juice intake during lactation with infant neurodevelopmental outcomes at 24 months

BACKGROUND

Our prior studies revealed that infant somatic growth is influenced by fructose in breast milk, and fructose in breast milk is increased in response to maternal sugar-sweetened beverage (SSB) intake in lactation. It is unknown whether infant neurodevelopmental outcomes are also influenced by maternal SSBs in lactation.

OBJECTIVES

To determine whether infant cognitive development at 24 postnatal months was influenced by maternal fructose consumption during lactation, and whether this relation persisted after accounting for maternal SSB and juice (SSB + J) intake.

METHODS

Hispanic mother-infant pairs (n = 88) were recruited across the spectrum of prepregnancy BMI. Mothers completed two 24-h dietary recalls at 1 and 6 postnatal months, and reported breastfeedings per day. The Bayley-III Scales of Infant Development were administered at 24 postnatal months to assess infant cognition. Linear regressions were used to examine associations, reported as unstandardized (B) coefficients, 95% CIs, and P values.

RESULTS

Mothers consumed 1656 ± 470 kcal, 21.8 ± 12 g fructose, and 2.5 ± 2.6 servings SSBs + J, and reported 6.9 ± 2.1 breastfeedings per day at 1 postnatal month. Controlling for maternal age, prepregnancy BMI, education level, kilocalories, infant age, sex, and birthweight revealed that infant cognitive development scores at 24 postnatal months correlated inversely with maternal fructose consumption at 1 postnatal month (B = -0.08; 95% CI = -0.13, -0.03; P < 0.01). The association of infant cognitive development scores with maternal fructose consumption was no longer significant after adjustment for maternal SSB + J intake (B = -0.05; 95% CI = -0.10, 0.00; P = 0.07), whereas maternal SSB + J intake was significant in the same model (B = -0.29; 95% CI = -0.52, -0.05; P = 0.02). Infant cognitive development scores were not associated with maternal fructose and SSB + J consumption at 6 postnatal months.

CONCLUSIONS

Our findings suggest that infant neurodevelopmental outcomes at 24 postnatal months can be adversely influenced by maternal fructose intake in early lactation, and this could be attributed to maternal SSB + J intake.

Antrodan Alleviates High-Fat and High-Fructose Diet-Induced Fatty Liver Disease in C57BL/6 Mice Model via AMPK/Sirt1/SREBP-1c/PPARγ Pathway

Non-alcoholic fatty liver disease (NAFLD) and -steatohepatitis (NASH) imply a state of excessive fat built-up in livers with/or without inflammation and have led to serious medical concerns in recent years. Antrodan (Ant), a purified β-glucan from A. cinnamomea has been shown to exhibit tremendous bioactivity, including hepatoprotective, antihyperlipidemic, antiliver cancer, and anti-inflammatory effects. Considering the already well-known alleviating bioactivity of A. cinnamomea for the alcoholic steatohepatitis (ASH), we propose that Ant can be beneficial to NAFLD, and that the AMPK/Sirt1/PPARγ/SREBP-1c pathways may be involved in such alleviations. To uncover this, we carried out this study with 60 male C57BL/6 mice fed high-fat high-fructose diet (HFD) for 60 days, in order to induce NAFLD/NASH. Mice were then grouped and treated (by oral administration) as: G1: control; G2: HFD (HFD control); G3: Ant, 40 mgkg (Ant control); G4: HFD+Orlistat (10 mg/kg) (as Orlistat control); G5: HFD+Ant L (20 mg/kg); and G6: HFD+Ant H (40 mg/kg) for 45 days. The results indicated Ant at 40 mg/kg effectively suppressed the plasma levels of malondialdehyde, total cholesterol, triglycerides, GOT, GPT, uric acid, glucose, and insulin; upregulated leptin, adiponectin, pAMPK, Sirt1, and down-regulated PPARγ and SREBP-1c. Conclusively, Ant effectively alleviates NAFLD via AMPK/Sirt1/CREBP-1c/PPARγ pathway.

The effects of antibiotics and melatonin on hepato-intestinal inflammation and gut microbial dysbiosis induced by a short-term high-fat diet consumption in rats

High-fat diet (HFD) consumption leads to metabolic disorders, gastrointestinal dysfunction and intestinal dysbiosis. Antibiotics also disrupt the composition of intestinal microbiota. The aim of the present study was to investigate the impact of a short-term feeding with HFD on oxidative status, enteric microbiota, intestinal motility and the effects of antibiotics and/or melatonin treatments on diet-induced hepato-intestinal dysfunction and inflammation. Male Sprague-Dawley rats were pair-fed with either standard chow or HFD (45 % fat) and were given tap water or melatonin (4 mg/kg per d) or melatonin plus antibiotics (ABX; neomycin, ampicillin, metronidazole; each 1 g/l) in drinking water for 2 weeks. On the 14th day, colonic motility was measured and the next day intestinal transit was assessed using charcoal propagation. Trunk blood, liver and intestine samples were removed for biochemical and histopathological evaluations, and faeces were collected for microbiota analysis. A 2-week HFD feeding increased blood glucose level and perirenal fat weight, induced low-level hepatic and intestinal inflammation, delayed intestinal transit, led to deterioration of epithelial tight junctions and overgrowth of colonic bacteria. Melatonin intake in HFD-fed rats reduced ileal inflammation, colonic motility and perirenal fat accumulation. ABX abolished increases in fat accumulation and blood glucose, reduced ileal oxidative damage, suppressed HFD-induced overgrowth in colonic bacteria, and reversed HFD-induced delay in intestinal transit; however, hepatic neutrophil accumulation, hepatic injury and dysfunction were further enhanced. In conclusion, the results demonstrate that even a short-term HFD ingestion results in hepato-intestinal inflammatory state and alterations in bacterial populations, which may be worsened with antibiotic intake, but alleviated by melatonin.

Reversion of down-regulation of intestinal multidrug resistance-associated protein 2 in fructose-fed rats by geraniol and vitamin C: Potential role of inflammatory response and oxidative stress

Intestinal multidrug resistance-associated protein 2 is an ABC transporter that limits the absorption of xenobiotics ingested orally, thus acting as essential component of the intestinal biochemical barrier. Metabolic Syndrome (MetS) is a pathological condition characterized by dyslipidemia, hyperinsulinemia, insulin resistance, chronic inflammation, and oxidative stress (OS). In a previous study we demonstrated that MetS-like conditions induced by fructose in drinking water (10% v/v, during 21 days), significantly reduced the expression and activity of intestinal Mrp2 in rats. We here evaluated the potential beneficial effect of geraniol or vitamin C supplementation, natural compounds with anti-inflammatory and anti-oxidant properties, in reverse fructose-induced Mrp2 alterations. After MetS-like conditions were induced (21 days), animals were cotreated with geraniol or vitamin C or vehicle for another 14 days. Decreased expression of Mrp2 protein and mRNA due to fructose administration was reversed by geraniol and by vitamin C, consistent with restoration of Mrp2 activity evaluated in everted intestinal sacs. Concomitantly, increased intestinal IL-1β and IL-6 levels induced by fructose were totally and partially counterbalanced, respectively, by geraniol administration. The intestinal redox unbalance generated by fructose was improved by geraniol and vitamin C, as evidenced by decreasing lipid peroxidation products and activity of Superoxide Dismutase and by normalizing glutathione reduced/oxidized glutathione ratio. The restoration effects exhibited by geraniol and vitamin C suggest that local inflammatory response and OS generated under MetS-like conditions represent important mediators of the intestinal Mrp2 down-regulation. Additionally, both agents could be considered of potential therapeutic value to preserve Mrp2 function under MetS conditions.

Short-Term Isocaloric Intake of a Fructose- but not Glucose-Rich Diet Affects Bacterial Endotoxin Concentrations and Markers of Metabolic Health in Normal Weight Healthy Subjects

SCOPE

Dietary pattern and impairments of intestinal barrier function are discussed to be critical in the development of metabolic impairments. Here, it is determined if an isocaloric exchange of complex carbohydrates with monosaccharides affects markers of intestinal permeability and metabolic health in healthy subjects.

METHODS AND RESULTS

After a dietary standardization for 4 days, all 12 subjects aged 21-33 years receive an isocaloric fructose- and glucose-enriched diet for 3 days separated by a wash-out phase. Anthropometry, blood pressure, markers of intestinal permeability and metabolic as well as inflammatory parameters are determined in blood samples or isolated peripheral blood mononuclear cells collected at baseline, after standardizations and the monosaccharide interventions, respectively. While anthropometric and inflammatory parameters are not changed, the intake of an isocaloric fructose- but not glucose-enriched diet is associated with a significant increase of bacterial endotoxin plasma levels and alanine aminotransferase activity in serum, while total plasma nitrate/nitrite concentrations are significantly decreased. In peripheral blood mononuclear cells, Toll like receptors 4, 2, and MYD88 mRNA expressions are significantly induced after the fructose-rich but not the glucose-rich diet.

CONCLUSION

In metabolically healthy subjects, even a short-term intake of a fructose-rich diet can elevate bacterial endotoxin levels and change markers of liver health and vascular endothelial function.

Nutritional Modulation of Innate Immunity: The Fat-Bile-Gut Connection

Altered nutritional behavior in Western societies has unleashed numerous metabolic disorders, intimately linked to profound disruptions of the immune system. Here we summarize how nutrition modulates innate immunity. We outline recent findings regarding nutrient signaling and we particularly focus on the collateral impact of nutrition on the microbiome and on the bile acid (BA) pool. We discuss how the integration of postprandial signals by the gut microbiota, along with the absorption routes of metabolites, differentially affects immune niches to orchestrate immune responses. Finally, we discuss the potential consequences of these signals in the light of trained immunity. A better understanding of nutrition signaling will permit the optimization of therapeutic and dietary strategies against the arising immune disorders.

Diet versus jaw bones: Lessons from experimental models and potential clinical implications

The consumption of different types of diets influences not only body health but the bone remodeling process as well. Nutritional components can directly affect maxillary and mandibular alveolar bone microarchitecture. In this review, we focus on the current knowledge regarding the influence of diets and dietary supplementation on alveolar bone. Accumulating evidence from experimental models suggests that carbohydrate- and fat-rich diets are detrimental for alveolar bone, whereas protective effects are associated with consumption of calcium, ω-3, and bioactive compounds. Little is known about the effects of protein-free and protein-rich diets, boron, vitamin C, vitamin E, zinc, and caffeine on alveolar bone remodeling. Adipokines and direct effects of nutritional components on bone cells are proposed mechanisms linking diet and bone. Results from animal models substantiate the role of nutritional components on alveolar bone. It is a well-built starting point for clinical studies on nutritional monitoring and intervention for patients with alveolar bone disorders, especially those who are treatment refractory.

Naringin prevents the inhibition of intestinal Ca2+ absorption induced by a fructose rich diet

This study tries to elucidate the mechanisms by which fructose rich diets (FRD) inhibit the rat intestinal Ca²⁺ absorption, and determine if any or all underlying alterations are prevented by naringin (NAR). Male rats were divided into: 1) controls, 2) treated with FRD, 3) treated with FRD and NAR. The intestinal Ca²⁺ absorption and proteins of the transcellular and paracellular Ca²⁺ pathways were measured. Oxidative/nitrosative stress and inflammation parameters were evaluated. FRD rats showed inhibition of the intestinal Ca²⁺ absorption and decrease in the protein expression of molecules of both Ca²⁺ pathways, which were blocked by NAR. FRD rats showed an increase in the superoxide anion, a decrease in the glutathione and in the enzymatic activities of the antioxidant system, as well as an increase in the NO content and in the nitrotyrosine content of proteins. They also exhibited an increase in both IL-6 and nuclear NF-κB. All these changes were prevented by NAR. In conclusion, FRD inhibit both pathways of the intestinal Ca²⁺ absorption due to the oxidative/nitrosative stress and inflammation. Since NAR prevents the oxidative/nitrosative stress and inflammation, it might be a drug to avoid alteration in the intestinal Ca²⁺ absorption caused by FRD.

Fructose Consumption in the Development of Obesity and the Effects of Different Protocols of Physical Exercise on the Hepatic Metabolism

Fructose consumption has been growing exponentially and, concomitant with this, the increase in the incidence of obesity and associated complications has followed the same behavior. Studies indicate that fructose may be a carbohydrate with greater obesogenic potential than other sugars. In this context, the liver seems to be a key organ for understanding the deleterious health effects promoted by fructose consumption. Fructose promotes complications in glucose metabolism, accumulation of triacylglycerol in the hepatocytes, and alterations in the lipid profile, which, associated with an inflammatory response and alterations in the redox state, will imply a systemic picture of insulin resistance. However, physical exercise has been indicated for the treatment of several chronic diseases. In this review, we show how each exercise protocol (aerobic, strength, or a combination of both) promote improvements in the obesogenic state created by fructose consumption as an improvement in the serum and liver lipid profile (high-density lipoprotein (HDL) increase and decrease triglyceride (TG) and low-density lipoprotein (LDL) levels) and a reduction of markers of inflammation caused by an excess of fructose. Therefore, it is concluded that the practice of aerobic physical exercise, strength training, or a combination of both is essential for attenuating the complications developed by the consumption of fructose.

High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions

High dietary fructose is a major contributor to insulin resistance and metabolic syndrome, disturbing tissue and organ functions. Fructose is mainly absorbed into systemic circulation by glucose transporter 2 (GLUT2) and GLUT5, and metabolized in liver to produce glucose, lactate, triglyceride (TG), free fatty acid (FFA), uric acid (UA) and methylglyoxal (MG). Its extrahepatic absorption and metabolism also take place. High levels of these metabolites are the direct dangerous factors. During fructose metabolism, ATP depletion occurs and induces oxidative stress and inflammatory response, disturbing functions of local tissues and organs to overproduce inflammatory cytokine, adiponectin, leptin and endotoxin, which act as indirect dangerous factors. Fructose and its metabolites directly and/or indirectly cause oxidative stress, chronic inflammation, endothelial dysfunction, autophagy and increased intestinal permeability, and then further aggravate the metabolic syndrome with tissue and organ dysfunctions. Therefore, this review addresses fructose-induced metabolic syndrome, and the disturbance effects of direct and/or indirect dangerous factors on the functions of liver, adipose, pancreas islet, skeletal muscle, kidney, heart, brain and small intestine. It is important to find the potential correlations between direct and/or indirect risk factors and healthy problems under excess dietary fructose consumption.

Dietary fructose as a risk factor for non-alcoholic fatty liver disease (NAFLD)

Glucose is a major energy source for the entire body, while fructose metabolism occurs mainly in the liver. Fructose consumption has increased over the last decade globally and is suspected to contribute to the increased incidence of non-alcoholic fatty liver disease (NAFLD). NAFLD is a manifestation of metabolic syndrome affecting about one-third of the population worldwide and has progressive pathological potential for liver cirrhosis and cancer through non-alcoholic steatohepatitis (NASH). Here we have reviewed the possible contribution of fructose to the pathophysiology of NAFLD. We critically summarize the current findings about several regulators, and their potential mechanisms, that have been studied in humans and animal models in response to fructose exposure. A novel hypothesis on fructose-dependent perturbation of liver regeneration and metabolism is advanced. Fructose intake could affect inflammatory and metabolic processes, liver function, gut microbiota, and portal endotoxin influx. The role of the brain in controlling fructose ingestion and the subsequent development of NAFLD is highlighted. Although the importance for fructose (over)consumption for NAFLD in humans is still debated and comprehensive intervention studies are invited, understanding of how fructose intake can favor these pathological processes is crucial for the development of appropriate noninvasive diagnostic and therapeutic approaches to detect and treat these metabolic effects. Still, lifestyle modification, to lessen the consumption of fructose-containing products, and physical exercise are major measures against NAFLD. Finally, promising drugs against fructose-induced insulin resistance and hepatic dysfunction that are emerging from studies in rodents are reviewed, but need further validation in human patients.

Intravital imaging of the cellular dynamics of LysM-positive cells in a murine corneal suture model

BACKGROUND

Corneal suturing is a surgical procedure used in patients with corneal trauma or transplants. It was reported that endogenous neutrophils are brightly labelled in gene-targeted mice expressing enhanced green fluorescent protein (eGFP) under the control of the endogenous lysozyme M promoter (LysM-eGFP mice).

METHODS

We applied intravital imaging methods to analyse in vivo the dynamics of LysM-positive granulocytes (neutrophils) in LysM-eGFP mice with corneal sutures and examined their role in the elicitation of neutrophil infiltration.

RESULTS

We found that in the presuturing state, neutrophils strongly positive for LysM were located in the periphery of the corneal stromal layer; none were present in the centre of the cornea. After introducing a corneal suture, neutrophils accumulated in limbal vessels and then migrated to the corneal side and the conjunctival side, suggesting that they derived from limbal vessels. Thereafter they accumulated towards the central corneal area, arriving at the suture about 7 h after its placement. Although corneal sutures may elicit the continuous infiltration of neutrophils, their number was markedly decreased by day 1 after suture removal and continued to decrease thereafter.

CONCLUSIONS

Our results showed that corneal sutures may elicit the continuous infiltration of neutrophils.

Western diet-induced hepatic steatosis and alterations in the liver transcriptome in adult Brown-Norway rats

Background

The purpose of this study was to investigate the effects of sub-chronic high fat, high sucrose diet (also termed ‘Westernized diet’ or WD) feeding on the liver transcriptome during early nonalcoholic fatty liver disease (NAFLD) development.

Methods

Brown Norway male rats (9 months of age) were randomly assigned to receive ad libitum access to a control (CTL; 14 % kcal fat, 1.2 % sucrose by weight) diet or WD (42 % kcal from fat, 34 % sucrose by weight) for 6 weeks.

Results

Six weeks of WD feeding caused hepatic steatosis development as evidenced by the 2.25-fold increase in liver triacylglycerol content, but did not induce advanced liver disease (i.e., no overt inflammation or fibrosis) in adult Brown Norway rats. RNA deep sequencing (RNA-seq) revealed that 94 transcripts were altered in liver by WD feeding (46 up-, 48 down-regulated, FDR < 0.05). Specifically, the top differentially regulated gene network by WD feeding was ‘Lipid metabolism, small molecular biochemistry, vitamin and mineral metabolism’ (Ingenuity Pathway Analysis (IPA) score 61). The top-regulated canonical signaling pathway in WD-fed rats was the ‘Superpathway of cholesterol biosynthesis’ (10/29 genes regulated, p = 1.68E-17), which coincides with a tendency for serum cholesterol levels to increase in WD-fed rats (p = 0.09). Remarkably, liver stearoyl-CoA desaturase (Scd) mRNA expression was by far the most highly-induced transcript in WD-fed rats (approximately 30-fold, FDR = 0.01) which supports previous literature underscoring this gene as a crucial target during NAFLD development.

Conclusions

In summary, sub-chronic WD feeding appears to increase hepatic steatosis development over a 6-week period but only induces select inflammation-related liver transcripts, mostly acute phase response genes. These findings continue to outline the early stages of NAFLD development prior to overt liver inflammation and advanced liver disease.

Dynamic weight bearing is an efficient and predictable method for evaluation of arthritic nociception and its pathophysiological mechanisms in mice

The assessment of articular nociception in experimental animals is a challenge because available methods are limited and subject to investigator influence. In an attempt to solve this problem, the purpose of this study was to establish the use of dynamic weight bearing (DWB) as a new device for evaluating joint nociception in an experimental model of antigen-induced arthritis (AIA) in mice. AIA was induced in Balb/c and C57BL/6 mice, and joint nociception was evaluated by DWB. Western Blotting and real-time PCR were used to determine protein and mRNA expression, respectively. DWB detected a dose- and time-dependent increase in joint nociception during AIA and was able to detect the dose-response effects of different classes of analgesics. Using DWB, it was possible to evaluate the participation of spinal glial cells (microglia and astrocytes) and cytokines (IL-1β and TNFα) for the genesis of joint nociception during AIA. In conclusion, the present results indicated that DWB is an effective, objective and predictable test to study both the pathophysiological mechanisms involved in arthritic nociception in mice and for evaluating novel analgesic drugs against arthritis.