Gender differences in rat plasma proteome in response to high-fat diet

Sex Difference is a Determinant of Gut Microbes and Their Metabolites SCFAs/MCFAs in High Fat Diet Fed Rats

There are gender differences in obesity and related metabolic diseases, but the mechanism of these differences has not been elucidated. Gut microbiota has been recently recognized as a pivotal determinant of obesity and related diseases. The aim of the present study was to investigate sex differences in gut microbiota and its metabolites in an obesity rat model induced by prolonged high-fat-diet (HFD) feeding. In this study, male and female Sprague-Dawley rats were fed normal chow or HFD for 16 weeks (n = 8 for each group). We found that comparing with male rats on HFD (MHFD), female rats on HFD (FHFD) gained more body weight percentage, while had lower body weight gain efficiency and less severity of hepatic steatosis. HFD induced decreased taxon diversity and richness of gut microbiota, and FHFD group had even lower diversity than MHFD group. Among key genera, HFD induced increased Bilophila in male rats but not in female rats. Compared with the MHFD group, FHFD group possessed increases of Akkermansia and Murimonas, and decreases of Acetanaerobacterium, Bacteroides, Bilophila, Blautia and Romboutsia. The levels of total SCFAs in colon contents were increased in tendency in HFD-fed rats of both sexes. FHFD group had increased propionate and decreased ratio of acetate to propionate and butyrate than MHFD group. For MCFAs, HFD induced increases in undecanoic acid and lauric acid in female rats but not in males. In conclusion, HFD induced sex-related alterations in gut microbiome and short/medium-chain fatty acids in rats.

Male and Female Rats Have Different Physiological Response to High-Fat High-Sucrose Diet but Similar Myocardial Sensitivity to Ischemia-Reperfusion Injury

Prediabetes is a strong predictor of type 2 diabetes and its associated cardiovascular complications, but few studies explore sexual dimorphism in this context. Here, we aim to determine whether sex influences physiological response to high-fat high-sucrose diet (HFS) and myocardial tolerance to ischemia-reperfusion injury. Male and female Wistar rats were subjected to standard (CTRL) or HFS diet for 5 months. Then, ex-vivo experiments on isolated perfused heart model were performed to evaluate tolerance to ischemia-reperfusion injury. HFS diet induced fasting hyperglycemia and increased body fat percent to a similar level in both sexes. However, glucose intolerance was more pronounced in female HFS. Cholesterol was increased only in female while male displayed higher level of plasmatic leptin. We observed increased heart weight to tibia length ratio only in males, but we showed a similar decrease in tolerance to ischemia-reperfusion injury in female and male HFS compared with respective controls, characterized by impaired cardiac function, energy metabolism and coronary flow during reperfusion. In conclusion, as soon as glucose intolerance and hyperglycemia develop, we observe higher sensitivity of hearts to ischemia-reperfusion injury without difference between males and females.

The association between circulating fetuin-A levels and type 2 diabetes mellitus risk: systematic review and meta-analysis of observational studies

BACKGROUND AND OBJECTIVE

Fetuin-A is a liver-derived circulating protein that is associated with insulin resistance and diabetes. The objective of this systematic review and meta-analysis of published observational studies was to investigate mean levels of fetuin-A in T2D patients and the relationship between blood fetuin-A levels and T2D risk.

MATERIALS AND METHODS

PubMed, Embase, Google Scholar, Web of Science, and The Cochrane Library were systematically searched for potential relevant studies up to 1 December 2016. Natural logarithm-transformed estimate risks, standard mean differences on the basis of Hedges's adjusted g, and 95% confidence intervals (CIs) were calculated for all eligible studies and were combined to measure the pooled data using random-effects model.

RESULTS

A total of 32 studies including 27 case-control and 5 cohort studies were included in the current study. Fetuin-A levels in T2D patients were significantly higher than control groups [Hedges' g = 1.73, 95% CI (1.25-2.22), P < 0.001], with significant heterogeneity across studies (P < 0.001, I ² = 98.46%). Findings from meta-analyses of cohort studies showed a statistically significant association between fetuin-A levels and T2D risk [rate ratio = 1.62, 95% CI (1.26-2.08), P < 0.001], with no significant heterogeneity (P = 0.10, I ² = 46.06%).

CONCLUSION

We found a significant relationship between the fetuin-A levels with T2D risk. Although fetuin-A may be as a potential screening and prediction biomarker or a therapeutic target in T2D patients, further studies are required in this regard.

High-fat diet-induced plasma protein and liver changes in obese rats can be attenuated by melatonin supplementation

Obesity triggers changes in protein expression in various organs that might participate in the pathogenesis of obesity. Melatonin has been reported to prevent or attenuate such pathological protein changes in several chronic diseases. However, such melatonin effects on plasma proteins have not yet been studied in an obesity model. Using a proteomic approach, we investigated the effect of melatonin on plasma protein profiles after rats were fed a high-fat diet (HFD) to induce obesity. We hypothesized that melatonin would attenuate abnormal protein expression in obese rats. After 10weeks of the HFD, animals displayed increased body weight and fat accumulation as well as increased glucose levels, indicating an obesity-induced prediabetes mellitus-like state. Two-dimensional gel electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry revealed 12 proteins whose expression was altered in response to the HFD and the melatonin treatment. The altered proteins are related to the development of liver pathology, such as cirrhosis (α1-antiproteinase), thrombosis (fibrinogen, plasminogen), and inflammation (mannose-binding protein A, complement C4, complement factor B), contributing to liver steatosis or hepatic cell death. Melatonin treatment most probably reduced the severity of the HFD-induced obesity by reducing the amplitude of HFD-induced plasma protein changes. In conclusion, we identified several potential biomarkers associated with the progression of obesity and its complications, such as liver damage. Furthermore, our findings reveal melatonin's beneficial effect of attenuating plasma protein changes and liver pathogenesis in obese rats.

Gender specific differences in the liver proteome of rats exposed to short term and low-concentration hexabromocyclododecane (HBCD)

The influence of short term (7-day) exposure of male rats to the brominated flame retardant hexabromocyclododecane (HBCD) was studied by investigation of the liver proteome, both in euthyroid and hypothyroid rats and by comparing results with general data on animal physiology and thyroid hormone, leptin, insulin and gonadotropin concentrations determined in parallel. Proteome analysis of liver tissue by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) revealed that only small protein pattern changes were induced by exposure in males, on just a few proteins with different functions and not involved in pathways in common. This is in contrast to previous findings in similarly exposed eu- and hypothyroid female rats, where general metabolic pathways had been shown to be affected. The largest gender-dependent effects concerned basal concentrations of liver proteins already in control and hypothyroid animals, involving mainly the pathways which were also differently affected by HBCD exposure. Among them were differences in lipid metabolism, which - upon exposure to HBCD - may also be the reason for the considerably higher ratio of γ-HBCD accumulated in white adipose tissue of exposed female rats compared to males. The results further elucidate the already suggested different sensitivity of genders towards HBCD exposure on the protein level, and confirm the need for undertaking toxicological animal experiments in both genders.

RNA-Seq Analysis of Abdominal Fat in Genetically Fat and Lean Chickens Highlights a Divergence in Expression of Genes Controlling Adiposity, Hemostasis, and Lipid Metabolism

Genetic selection for enhanced growth rate in meat-type chickens (Gallus domesticus) is usually accompanied by excessive adiposity, which has negative impacts on both feed efficiency and carcass quality. Enhanced visceral fatness and several unique features of avian metabolism (i.e., fasting hyperglycemia and insulin insensitivity) mimic overt symptoms of obesity and related metabolic disorders in humans. Elucidation of the genetic and endocrine factors that contribute to excessive visceral fatness in chickens could also advance our understanding of human metabolic diseases. Here, RNA sequencing was used to examine differential gene expression in abdominal fat of genetically fat and lean chickens, which exhibit a 2.8-fold divergence in visceral fatness at 7 wk. Ingenuity Pathway Analysis revealed that many of 1687 differentially expressed genes are associated with hemostasis, endocrine function and metabolic syndrome in mammals. Among the highest expressed genes in abdominal fat, across both genotypes, were 25 differentially expressed genes associated with de novo synthesis and metabolism of lipids. Over-expression of numerous adipogenic and lipogenic genes in the FL chickens suggests that in situ lipogenesis in chickens could make a more substantial contribution to expansion of visceral fat mass than previously recognized. Distinguishing features of the abdominal fat transcriptome in lean chickens were high abundance of multiple hemostatic and vasoactive factors, transporters, and ectopic expression of several hormones/receptors, which could control local vasomotor tone and proteolytic processing of adipokines, hemostatic factors and novel endocrine factors. Over-expression of several thrombogenic genes in abdominal fat of lean chickens is quite opposite to the pro-thrombotic state found in obese humans. Clearly, divergent genetic selection for an extreme (2.5-2.8-fold) difference in visceral fatness provokes a number of novel regulatory responses that govern growth and metabolism of visceral fat in this unique avian model of juvenile-onset obesity and glucose-insulin imbalance.

Mitigating or exacerbating effects of maternal-fetal programming of female mice through the food choice environment

Humans live, eat, and become overweight/obese in complex surroundings where there are many available food choices. Prenatal exposure to poor food choices predisposes offspring to increased negative health risks, including obesity. Many animal experiments have analyzed intergenerational body weight parameters in an environment without food choices, which may not be directly translatable to the human food environment. In this study, offspring from mothers with a defined high-fat diet (HFD) or low-fat diet (LFD) were arbitrarily assigned to either an exclusively LFD or HFD or to a diet where they have a choice between LFD and HFD (choice diet). Offspring displayed negative outcomes of increased body weight, body fat, serum leptin, and blood glucose levels when given the choice diet compared with offspring on the LFD. Conversely, improved energy expenditure was found for offspring given the choice diet compared with offspring from HFD dams given LFD. In addition, maternal diet-specific influences on offspring metabolic parameters were identified, especially in offspring from HFD dams, including positive outcomes of reduced leptin in LFD offspring, reduced corticosterone and cholesterol levels in HFD offspring, and increased exercise levels in choice offspring, as well as the negative outcome of increased calorie intake in LFD offspring from HFD dams. This defined model can now be used as the basis for future studies to characterize the cycle of inter- and intragenerational obesity and whether more realistic diet environments, especially those including choice, can mitigate phenotype.

Sex-dependent expression of caveolin 1 in response to sex steroid hormones is closely associated with development of obesity in rats

Caveolin-1 (CAV1) is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD) and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2) and androgen (dihydrotestosterone, DHT) had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL) and uncoupling protein 1 (UCP1) in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1.

Chronic high fat diet consumption impairs sensorimotor gating in mice

Chronic intake of high fat diets (HFD) has been long recognized to induce neuronal adaptations and impair elementary cognitive functions. Yet, the consequences of chronic HFD consumption on central information processing remain elusive. The present study thus explored the impact of chronic HFD consumption on pre-attentive central information processing using the paradigm of prepulse inhibition (PPI) of the acoustic startle reflex in mice. Animals were fed an experimental diet with 60% of its calories derived from fat, and were compared to control low fat diet (LFD, 10% calories from fat) fed animals. A first experimental series demonstrated that adult mice exposed to chronic HFD throughout adolescent development displayed significant deficits in PPI compared to LFD-fed mice. Identical chronic HFD treatment further led to presynaptic dopaminergic abnormalities in the form of increased tyrosine hydroxylase density in the nucleus accumbens core and shell subregions. Moreover, we found that tyrosine hydroxylase density in the nucleus accumbens shell negatively correlated with the mean PPI scores, suggesting a potential contribution of the accumbal dopamine system to HFD-induced PPI deficits. This impression was further supported by an additional series of experiments showing that the HFD-induced attenuation of PPI can be mitigated by systemic administration of the dopamine receptor antagonist haloperidol. Finally, HFD feeding was sufficient to disrupt PPI when its exposure was restricted to the peripubertal period, whilst the same manipulation failed to affect PPI when limited to adulthood. In conclusion, our findings emphasize that pre-attentive information processing as assessed by the PPI paradigm is highly sensitive to nutritional factors in the form of chronic HFD consumption, especially when initiated during peripubertal maturation. It is likely that the disrupting effects of HFD on sensorimotor gating involve, at least in part, dopaminergic mechanisms.

Responses of Mytilus galloprovincialis to bacterial challenges by metabolomics and proteomics

Pathogens can cause diseases and lead to massive mortalities of aquaculture animals and substantial economic loss. In this work, we studied the responses induced by Micrococcus luteus and Vibrio anguillarum in gill of mussel Mytilus galloprovincialis at protein and metabolite levels. Metabolic biomarkers (e.g., amino acids, betaine, ATP) suggested that both M. luteus and V. anguillarum induced disturbances in energy metabolism and osmotic regulation. The unique and some more remarkably altered metabolic biomarkers (threonine, alanine, aspartate, taurine, succinate) demonstrated that V. anguillarum could cause more severe disturbances in osmotic regulation and energy metabolism. Proteomic biomarkers (e.g., goose-type lysozyme 2, matrilin, ependymin-related protein, peptidyl-prolyl cis-trans isomerases) indicated that M. luteus caused immune stress, and disturbances in signaling pathways and protein synthesis. However, V. anguillarum mainly induced oxidative stress and disturbance in energy metabolism in mussel gills indicated by altered procollagen-proline dioxygenase, protein disulfide isomerase, nucleoside diphosphate kinases, electron transfer flavoprotein and glutathione S-transferase. This work confirmed that an integration of proteomics and metabolomics could provide an insightful view into the effects of pathogens to the marine mussel M. galloprovincialis.

Gender dimorphism in regulation of plasma proteins in streptozotocin-induced diabetic rats

In the present study, we examined differentially regulated plasma proteins between healthy control and streptozotocin (STZ)-induced male and female diabetic rats by 2DE-based proteomic analysis. Animal experiments revealed that significantly lower plasma insulin levels were observed in female diabetic rats, consequently resulting in higher blood glucose levels in female diabetic rats. Importantly, plasma levels of sex hormones were significantly altered in a gender-dependent manner before and after STZ treatment. Results of the animal experiment indicated the existence of sexual dimorphism in the regulation of plasma proteins between healthy control and diabetic rats. Plasma proteome analysis enabled us to identify a total of 38 proteins showing sexual dimorphic regulation patterns. In addition, for the first time, we identified several differentially regulated plasma proteins between healthy control and diabetic rats, including apolipoprotein E, fetuin B, α-1-acid glycoprotein, β-2-glycoprotein 1, 3-hydroxyanthranilate 3,4-dioxygenase, and serum amyloid P-component. To the best of our knowledge, this is the first proteomic approach to address sexual dimorphism in diabetic animals. These proteomic data on gender-dimorphic regulation of plasma proteins provide valuable information that can be used for evidence-based gender-specific clinical treatment of diabetes.

Proteomic and cytokine plasma biomarkers for predicting progression from colorectal adenoma to carcinoma in human patients

In the present study, we screened proteomic and cytokine biomarkers between patients with adenomatous polyps and colorectal cancer (CRC) in order to improve our understanding of the molecular mechanisms behind turmorigenesis and tumor progression in CRC. To this end, we performed comparative proteomic analysis of plasma proteins using a combination of 2DE and MS as well as profiled differentially regulated cytokines and chemokines by multiplex bead analysis. Proteomic analysis identified 11 upregulated and 13 downregulated plasma proteins showing significantly different regulation patterns with diagnostic potential for predicting progression from adenoma to carcinoma. Some of these proteins have not previously been implicated in CRC, including upregulated leucine-rich α-2-glycoprotein, hemoglobin subunit β, Ig α-2 chain C region, and complement factor B as well as downregulated afamin, zinc-α-2-glycoprotein, vitronectin, and α-1-antichymotrypsin. In addition, plasma levels of three cytokines/chemokines, including interleukin-8, interferon gamma-induced protein 10, and tumor necrosis factor α, were remarkably elevated in patients with CRC compared to those with adenomatous polyps. Although further clinical validation is required, these proteins and cytokines can be established as novel biomarkers for CRC and/or its progression from colon adenoma.

Comparative hepatic proteome analysis between lean and obese rats fed a high-fat diet reveals the existence of gender differences

Gender differences in obesity stem from metabolic and hormonal differences between sexes and contribute to differences between women and men in health risks attributable to obesity. We hypothesized that liver may be an ideal target for the evaluation of gender differences in obesity development in response to a high-fat diet (HFD). Therefore, to test this hypothesis, we performed a global proteome analysis in the liver of lean and obese rats of both genders who were fed an HFD through 2-DE combined with MALDI-TOF-MS. When rats were exposed to HFD, male rats gained more body weight with increased values of plasma biochemical parameters than female rats. Image analysis and further statistical analysis of a 2-DE protein map allowed for the detection and identification of 34 proteins that were significantly modulated in a gender-dependent manner. We found 19 proteins showing identical gender-different regulation in both normal diet (ND) and HFD. Five proteins also showed clear gender differences in both ND and HFD; however, their regulation modes in HFD were opposite to those in ND. Of particular interest, 10 proteins showed gender differences only in either ND or HFD rats. Present proteomic insight into gender-dimorphic protein modulation in liver would aid in the improvement of gender awareness in the health-care system and in implementation of evidence-based gender-specific clinical recommendations.