Limosilactobacillus reuteri DSM 17938 reverses gut metabolic dysfunction induced by Western diet in adult rats.

Introduction: Microencapsulation of probiotic bacteria is an efficient and innovative new technique aimed at preserving bacterial survival in the hostile conditions of the gastrointestinal tract. However, understanding whether a microcapsule preserves the effectiveness of the bacterium contained within it is of fundamental importance. Methods: Male Wistar rats aged 90 days were fed a control diet or a Western diet for 8 weeks, with rats fed the Western diet divided into three groups: one receiving the diet only (W), the second group receiving the Western diet and free L. reuteri DSM 17938 (WR), and the third group receiving the Western diet and microencapsulated L. reuteri DSM 17938 (WRM). After 8 weeks of treatment, gut microbiota composition was evaluated, together with occludin, one of the tight junction proteins, in the ileum and the colon. Markers of inflammation were also quantified in the portal plasma, ileum, and colon, as well as markers for gut redox homeostasis. Results: The Western diet negatively influenced the intestinal microbiota, with no significant effect caused by supplementation with free and microencapsulated L. reuteri. However, L. reuteri, in both forms, effectively preserved the integrity of the intestinal barrier, thus protecting enterocytes from the development of inflammation and oxidative stress. Conclusion: From these whole data, it emerges that L. reuteri DSM 17938 can be an effective probiotic in preventing the unhealthy consequences of the Western diet, especially in the gut, and that microencapsulation preserves the probiotic effects, thus opening the formulation of new preparations to be able to improve gut function independent of dietary habits.

Reviewing the state of biosensors and lab-on-a- chip technologies: opportunities for extreme environments and space exploration.

The space race is entering a new era of exploration, in which the number of robotic and human missions to various places in our solar system is rapidly increasing. Despite the recent advances in propulsion and life support technologies, there is a growing need to perform analytical measurements and laboratory experiments across diverse domains of science, while keeping low payload requirements. In this context, lab-on-a-chip nanobiosensors appear to be an emerging technology capable of revolutionizing space exploration, given their low footprint, high accuracy, and low payload requirements. To date, only some approaches for monitoring astronaut health in spacecraft environments have been reported. Although non-invasive molecular diagnostics, like lab-on-a-chip technology, are expected to improve the quality of long-term space missions, their application to monitor microbiological and environmental variables is rarely reported, even for analogous extreme environments on Earth. The possibility of evaluating the occurrence of unknown or unexpected species, identifying redox gradients relevant to microbial metabolism, or testing for specific possible biosignatures, will play a key role in the future of space microbiology. In this review, we will examine the current and potential roles of lab-on-a-chip technology in space exploration and in extreme environment investigation, reporting what has been tested so far, and clarifying the direction toward which the newly developed technologies of portable lab-on-a-chip sensors are heading for exploration in extreme environments and in space.

Short-term fructose feeding alters tissue metabolic pathways by modulating microRNAs expression both in young and adult rats.

Dietary high fructose (HFrD) is known as a metabolic disruptor contributing to the development of obesity, diabetes, and dyslipidemia. Children are more sensitive to sugar than adults due to the distinct metabolic profile, therefore it is especially relevant to study the metabolic alterations induced by HFrD and the mechanisms underlying such changes in animal models of different ages. Emerging research suggests the fundamental role of epigenetic factors such as microRNAs (miRNAs) in metabolic tissue injury. In this perspective, the aim of the present study was to investigate the involvement of miR-122-5p, miR-34a-5p, and miR-125b-5p examining the effects induced by fructose overconsumption and to evaluate whether a differential miRNA regulation exists between young and adult animals. We used young rats (30 days) and adult rats (90 days) fed on HFrD for a short period (2 weeks) as animal models. The results indicate that both young and adult rats fed on HFrD exhibit an increase in systemic oxidative stress, the establishment of an inflammatory state, and metabolic perturbations involving the relevant miRNAs and their axes. In the skeletal muscle of adult rats, HFrD impair insulin sensitivity and triglyceride accumulation affecting the miR-122-5p/PTP1B/P-IRS-1(Tyr612) axis. In liver and skeletal muscle, HFrD acts on miR-34a-5p/SIRT-1: AMPK pathway resulting in a decrease of fat oxidation and an increase in fat synthesis. In addition, liver and skeletal muscle of young and adult rats exhibit an imbalance in antioxidant enzyme. Finally, HFrD modulates miR-125b-5p expression levels in liver and white adipose tissue determining modifications in de novo lipogenesis. Therefore, miRNA modulation displays a specific tissue trend indicative of a regulatory network that contributes in targeting genes of various pathways, subsequently yielding extensive effects on cell metabolism.

Age-Dependent Skeletal Muscle Mitochondrial Response to Short-Term Increased Dietary Fructose.

The harmful effect of a long-term high-fructose diet is well established, but the age-dependent physiological responses that can be triggered by a short-term high-fructose diet in skeletal muscles have not been deeply explored. Therefore, the aim of this work was to compare the alterations in mitochondrial energetic and insulin responsiveness in the skeletal muscle induced by a short-term (2 weeks) fructose feeding in rats of different ages. For this purpose, fructose and uric acid levels, insulin sensitivity, mitochondrial bioenergetics and oxidative status were evaluated in the skeletal muscles from young (30 days old) and adult (90 days old) rats. We showed that, even in the short term, a high-fructose diet has a strong impact on skeletal muscle metabolism, with more marked effects in young rats than in adults ones. In fact, despite both groups showing a decrease in insulin sensitivity, the marked mitochondrial dysfunction was found only in the young rats, thus leading to an increase in the mitochondrial production of ROS, and therefore, in oxidative damage. These findings underscore the need to reduce fructose consumption, especially in young people, to preserve the maintenance of a metabolically healthy status.

Fructose Diet-Associated Molecular Alterations in Hypothalamus of Adolescent Rats: A Proteomic Approach.

BACKGROUND: The enhanced consumption of fructose as added sugar represents a major health concern. Due to the complexity and multiplicity of hypothalamic functions, we aim to point out early molecular alterations triggered by a sugar-rich diet throughout adolescence, and to verify their persistence until the young adulthood phase. METHODS: Thirty days old rats received a high-fructose or control diet for 3 weeks. At the end of the experimental period, treated animals were switched to the control diet for further 3 weeks, and then analyzed in comparison with those that were fed the control diet for the entire experimental period. RESULTS: Quantitative proteomics identified 19 differentially represented proteins, between control and fructose-fed groups, belonging to intermediate filament cytoskeleton, neurofilament, pore complex and mitochondrial respiratory chain complexes. Western blotting analysis confirmed proteomic data, evidencing a decreased abundance of mitochondrial respiratory complexes and voltage-dependent anion channel 1, the coregulator of mitochondrial biogenesis PGC-1α, and the protein subunit of neurofilaments α-internexin in fructose-fed rats. Diet-associated hypothalamic inflammation was also detected. Finally, the amount of brain-derived neurotrophic factor and its high-affinity receptor TrkB, as well as of synaptophysin, synaptotagmin, and post-synaptic protein PSD-95 was reduced in sugar-fed rats. Notably, deregulated levels of all proteins were fully rescued after switching to the control diet. CONCLUSIONS: A short-term fructose-rich diet in adolescent rats induces hypothalamic inflammation and highly affects mitochondrial and cytoskeletal compartments, as well as the level of specific markers of brain function; above-reported effects are reverted after switching animals to the control diet.

Long-Lasting Impact of Sugar Intake on Neurotrophins and Neurotransmitters from Adolescence to Young Adulthood in Rat Frontal Cortex.

The detrimental impact of fructose, a widely used sweetener in industrial foods, was previously evidenced on various brain regions. Although adolescents are among the highest consumers of sweet foods, whether brain alterations induced by the sugar intake during this age persist until young adulthood or are rescued returning to a healthy diet remains largely unexplored. To shed light on this issue, just weaned rats were fed with a fructose-rich or control diet for 3 weeks. At the end of the treatment, fructose-fed rats underwent a control diet for a further 3 weeks until young adulthood phase and compared with animals that received from the beginning the healthy control diet. We focused on the consequences induced by the sugar on the main neurotrophins and neurotransmitters in the frontal cortex, as its maturation continues until late adolescence, thus being the last brain region to achieve a full maturity. We observed that fructose intake induces inflammation and oxidative stress, alteration of mitochondrial function, and changes of brain-derived neurotrophic factor (BDNF) and neurotrophin receptors, synaptic proteins, acetylcholine, dopamine, and glutamate levels, as well as increased formation of the glycation end-products Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL). Importantly, many of these alterations (BDNF, CML, CEL, acetylcholinesterase activity, dysregulation of neurotransmitters levels) persisted after switching to the control diet, thus pointing out to the adolescence as a critical phase, in which extreme attention should be devoted to limit an excessive consumption of sweet foods that can affect brain physiology also in the long term.

Skeletal muscle insulin resistance and adipose tissue hypertrophy persist beyond the reshaping of gut microbiota in young rats fed a fructose-rich diet.

To investigate whether short term fructose-rich diet induces changes in the gut microbiota as well as in skeletal muscle and adipose tissue physiology and verify whether they persist even after fructose withdrawal, young rats of 30 d of age were fed for 3 weeks a fructose-rich or control diet. At the end of the 3-weeks period, half of the rats from each group were maintained for further 3 weeks on a control diet. Metagenomic analysis of gut microbiota and short chain fatty acids levels (faeces and plasma) were investigated. Insulin response was evaluated at the whole-body level and both in skeletal muscle and epididymal adipose tissue, together with skeletal muscle mitochondrial function, oxidative stress, and lipid composition. In parallel, morphology and physiological status of epididymal adipose tissue was also evaluated. Reshaping of gut microbiota and increased content of short chain fatty acids was elicited by the fructose diet and abolished by switching back to control diet. On the other hand, most metabolic changes elicited by fructose-rich diet in skeletal muscle and epididymal adipose tissue persisted after switching to control diet. Increased dietary fructose intake even on a short-time basis elicits persistent changes in the physiology of metabolically relevant tissues, such as adipose tissue and skeletal muscle, through mechanisms that go well beyond the reshaping of gut microbiota. This picture delineates a harmful situation, in particular for the young populations, posed at risk of metabolic modifications that may persist in their adulthood.

Gut and liver metabolic responses to dietary fructose - are they reversible or persistent after switching to a healthy diet?

The link between increased fructose intake and induction of gut and liver dysfunction has been established, while it remains to be understood whether this damage is reversible, particularly in the young population, in which the intake of fructose has reached dramatic levels. To this end, young (30 days old) rats were fed a fructose-rich or control diet for 3 weeks to highlight the early response of the gut and liver to increased fructose intake. After this period, fructose-fed rats were returned to a control diet for 3 weeks and compared to the rats that received the control diet for the entire period to identify whether fructose-induced changes in the gut-liver axis persist or not after switching back to a control diet. Glucose transporter 5 and the tight junction protein occludin were assessed in the ileum and colon. Markers of inflammation and redox homeostasis as well as fructose and uric acid levels were also evaluated in the ileum, colon and liver. From the whole data, it is seen that metabolic derangement elicited by a fructose-rich diet, even after a brief period of intake, is fully reversed in the liver by a period of fructose withdrawal, while the alterations persist in the gut, especially in the ileum. In conclusion, given the increasing consumption of fructose-rich foods in young populations, the present results highlight the risk arising from gut persistent alterations even after the end of a fructose-rich diet. Therefore, dietary recommendations of reducing the intake of this simple sugar is mandatory to avoid not only the related metabolic alterations but also the persistence of these detrimental changes.

Prenatal Exposure to BPA: The Effects on Hepatic Lipid Metabolism in Male and Female Rat Fetuses.

Bisphenol A (BPA) is an organic chemical compound widely used for manufacturing plastics. BPA exposure originates principally from the diet, but it can also originate from dermal contact. In over 90% of individuals, including pregnant women, BPA is detectable in several body fluids. The effects of this exposure on the fetus are under active investigation in several research laboratories. The aim of our work was to study the impact of prenatal exposure to BPA in the liver of rat fetuses from a sex-dependent point of view. We particularly investigated the effects of prenatal BPA exposure on hepatic lipids because of their crucial role, not only for the liver, but also for the whole-body functions. Our results demonstrate that the liver of rat fetuses, in utero exposed to a very low dose of BPA (2.5 µg/kg/day), displays significant modulations with regard to proteins involved in cholesterol and fatty acid biosynthesis and trafficking. Moreover, an impact on inflammatory process has been observed. All these effects are dependent on sex, being observable only in female rat fetuses. In conclusion, this work demonstrates that maternal exposure to BPA compromises hepatic lipid metabolism in female offspring, and it also reveals the perspective impact of BPA on human health at doses currently considered safe.

Fructose Removal from the Diet Reverses Inflammation, Mitochondrial Dysfunction, and Oxidative Stress in Hippocampus.

Young age is often characterized by high consumption of processed foods and fruit juices rich in fructose, which, besides inducing a tendency to become overweight, can promote alterations in brain function. The aim of this study was therefore to (a) clarify brain effects resulting from fructose consumption in juvenile age, a critical phase for brain development, and (b) verify whether these alterations can be rescued after removing fructose from the diet. Young rats were fed a fructose-rich or control diet for 3 weeks. Fructose-fed rats were then fed a control diet for a further 3 weeks. We evaluated mitochondrial bioenergetics by high-resolution respirometry in the hippocampus, a brain area that is critically involved in learning and memory. Glucose transporter-5, fructose and uric acid levels, oxidative status, and inflammatory and synaptic markers were investigated by Western blotting and spectrophotometric or enzyme-linked immunosorbent assays. A short-term fructose-rich diet induced mitochondrial dysfunction and oxidative stress, associated with an increased concentration of inflammatory markers and decreased Neurofilament-M and post-synaptic density protein 95. These alterations, except for increases in haptoglobin and nitrotyrosine, were recovered by returning to a control diet. Overall, our results point to the dangerous effects of excessive consumption of fructose in young age but also highlight the effect of partial recovery by switching back to a control diet.

Prolonged Changes in Hepatic Mitochondrial Activity and Insulin Sensitivity by High Fructose Intake in Adolescent Rats.

Persistence of damage induced by unhealthy diets during youth has been little addressed. Therefore, we investigated the impact of a short-term fructose-rich diet on liver metabolic activity in adolescent rats and the putative persistence of alterations after removing fructose from the diet. Adolescent rats were fed a fructose-rich diet for three weeks and then switched to a control diet for further three weeks. Body composition and energy balance were not affected by fructose-rich diet, while increased body lipids and lipid gain were found after the rescue period. Switching to a control diet reversed the upregulation of plasma fructose, uric acid, lipocalin, and haptoglobin, while plasma triglycerides, alanine aminotransferase, lipopolysaccharide, and tumor necrosis factor alpha remained higher. Hepatic steatosis and ceramide were increased by fructose-rich diet, but reversed by returning to a control diet, while altered hepatic response to insulin persisted. Liver fatty acid synthase and stearoyl-CoA desaturase (SCD) activities were upregulated by fructose-rich diet, and SCD activity remained higher after returning to the control diet. Fructose-induced upregulation of complex II-driven mitochondrial respiration, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, and peroxisome proliferator activated receptor α also persisted after switching to control diet. In conclusion, our results show prolonged fructose-induced dysregulation of liver metabolic activity.

JNK1 ablation improves pancreatic ß-cell mass and function in db/db diabetic mice without affecting insulin sensitivity and adipose tissue inflammation.

The cJun N-terminal Kinases (JNK) emerged as a major link between obesity and insulin resistance, but their role in the loss of pancreatic ß-cell mass and function driving the progression from insulin resistance to type-2 diabetes and in the complications of diabetes was not investigated to the same extent. Furthermore, it was shown that pan-JNK inhibition exacerbates kidney damage in the db/db model of obesity-driven diabetes. Here we investigate the role of JNK1 in the db/db model of obesity-driven type-2 diabetes. Mice with systemic ablation of JNK1 (JNK1-/-) were backcrossed for more than 10 generations in db/+ C57BL/KS mice to generate db/db-JNK1-/- mice and db/db control mice. To define the role of JNK1 in the loss of ß-cell mass and function occurring during obesity-driven diabetes we performed comprehensive metabolic phenotyping, evaluated steatosis and metabolic inflammation, performed morphometric and cellular composition analysis of pancreatic islets, and evaluated kidney function in db/db-JNK1-/- mice and db/db controls. db/db-JNK1-/- mice and db/db control mice developed insulin resistance, fatty liver, and metabolic inflammation to a similar extent. However, db/db-JNK1-/- mice displayed better glucose tolerance and improved insulin levels during glucose tolerance test, higher pancreatic insulin content, and larger pancreatic islets with more ß-cells than db/db mice. Finally, albuminuria, kidney histopathology, kidney inflammation and oxidative stress in db/db-JNK1-/- mice and in db/db mice were similar. Our data indicate that selective JNK1 ablation improves glucose tolerance in db/db mice by reducing the loss of functional ß-cells occurring in the db/db mouse model of obesity-driven diabetes, without significantly affecting metabolic inflammation, steatosis, and insulin sensitivity. Furthermore, we have found that, differently from what previously reported for pan-JNK inhibitors, selective JNK1 ablation does not exacerbate kidney dysfunction in db/db mice. We conclude that selective JNK1 inactivation may have a superior therapeutic index than pan-JNK inhibition in obesity-driven diabetes.

A Short-Term Western Diet Impairs Cholesterol Homeostasis and Key Players of Beta Amyloid Metabolism in Brain of Middle Aged Rats.

SCOPE: Cholesterol homeostasis is crucial for brain functioning. Unhealthy nutrition can influence cerebral physiology, but the effect of western diets on brain cholesterol homeostasis, particularly at middle age, is unknown. Given the link between brain cholesterol alteration and beta amyloid production, the aim is to evaluate whether a diet rich in fat and fructose affects the protein network implicated in cholesterol synthesis and shuttling between glial cells and neurons, as well as crucial markers of beta amyloid metabolism. METHODS AND RESULTS: Middle aged rats are fed a high fat-high fructose (HFF) or a control diet for 4 weeks. Inflammatory markers and cholesterol levels significantly increase in hippocampus of HFF rats. A higher activation of 3-hydroxy 3-methylglutaryl coenzyme-A reductase, coupled with lower levels of apolipoprotein E, LXR-beta, and lipoproteins receptors is measured in hippocampus from HFF rats. The alteration of critical players of cholesterol homeostasis is associated with increased level of amyloid precursor protein, presenilin 1, and nicastrin, and decreased level of insulin degrading enzyme. CONCLUSIONS: Overall these data show that a western diet is associated with perturbation of cholesterol homeostasis in middle aged rats, mostly in hippocampus. This might trigger molecular events involved in the onset of neurodegenerative diseases.

A probiotic treatment increases the immune response induced by the nasal delivery of spore-adsorbed TTFC.

BACKGROUND: Spore-forming bacteria of the Bacillus genus are widely used probiotics known to exert their beneficial effects also through the stimulation of the host immune response. The oral delivery of B. toyonensis spores has been shown to improve the immune response to a parenterally administered viral antigen in mice, suggesting that probiotics may increase the efficiency of systemic vaccines. We used the C fragment of the tetanus toxin (TTFC) as a model antigen to evaluate whether a treatment with B. toyonensis spores affected the immune response to a mucosal antigen. RESULTS: Purified TTFC was given to mice by the nasal route either as a free protein or adsorbed to B. subtilis spores, a mucosal vaccine delivery system proved effective with several antigens, including TTFC. Spore adsorption was extremely efficient and TTFC was shown to be exposed on the spore surface. Spore-adsorbed TTFC was more efficient than the free antigen in inducing an immune response and the probiotic treatment improved the response, increasing the production of TTFC-specific secretory immunoglobin A (sIgA) and causing a faster production of serum IgG. The analysis of the induced cytokines indicated that also the cellular immune response was increased by the probiotic treatment. A 16S RNA-based analysis of the gut microbial composition did not show dramatic differences due to the probiotic treatment. However, the abundance of members of the Ruminiclostridium 6 genus was found to correlate with the increased immune response of animals immunized with the spore-adsorbed antigen and treated with the probiotic. CONCLUSION: Our results indicate that B. toyonensis spores significantly contribute to the humoral and cellular responses elicited by a mucosal immunization with spore-adsorbed TTFC, pointing to the probiotic treatment as an alternative to the use of adjuvants for mucosal vaccinations.

Adipose Tissue and Brain Metabolic Responses to Western Diet-Is There a Similarity between the Two?

Dietary fats and sugars were identified as risk factors for overweight and neurodegeneration, especially in middle-age, an earlier stage of the aging process. Therefore, our aim was to study the metabolic response of both white adipose tissue and brain in middle aged rats fed a typical Western diet (high in saturated fats and fructose, HFF) and verify whether a similarity exists between the two tissues. Specific cyto/adipokines (tumor necrosis factor alpha (TNF-α), adiponectin), critical obesity-inflammatory markers (haptoglobin, lipocalin), and insulin signaling or survival protein network (insulin receptor substrate 1 (IRS), Akt, Erk) were quantified in epididymal white adipose tissue (e-WAT), hippocampus, and frontal cortex. We found a significant increase of TNF-α in both e-WAT and hippocampus of HFF rats, while the expression of haptoglobin and lipocalin was differently affected in the various tissues. Interestingly, adiponectin amount was found significantly reduced in e-WAT, hippocampus, and frontal cortex of HFF rats. Insulin signaling was impaired by HFF diet in e-WAT but not in brain. The above changes were associated with the decrease in brain derived neurotrophic factor (BDNF) and synaptotagmin I and the increase in post-synaptic protein PSD-95 in HFF rats. Overall, our investigation supports for the first time similarities in the response of adipose tissue and brain to Western diet.

Early Hepatic Oxidative Stress and Mitochondrial Changes Following Western Diet in Middle Aged Rats.

To assess the effect of 4 weeks of high fat-high fructose feeding on whole body composition, energy balance, specific markers of oxidative stress and inflammation, and insulin sensitivity in the liver of middle-aged rats, rats (1 year) were fed a diet rich in saturated fatty acids and fructose (HFF rats), mimicking the "Western diet", and compared with rats of the same age that were fed a low fat diet (LF rats). HFF rats exhibited a significant increase in the gain of body weight, energy, and lipids compared to LF rats. HFF rats also showed hepatic insulin resistance, together with an increase in plasma triglycerides, cholesterol, and tumor necrosis factor alpha. Hepatic lipids, triglycerides and cholesterol were higher in HFF rats, while a significant decrease in Stearoyl-CoA desaturase activity was found in this tissue. A marked increase in the protein amount of complex I, concomitant to a decrease in its contribution to mitochondrial respiration, was found in HFF rats. Lipid peroxidation and Nitro-Tyrosine content, taken as markers of oxidative stress, as well as NADPH oxidase activity, were significantly higher in HFF rats, while the antioxidant enzyme catalase decreased in these rats. Myeloperoxidase activity and lipocalin content increased, while peroxisome proliferator activated receptor gamma decreased in HFF rats. The present results provide evidence that middle-aged rats show susceptibility to a short-term "Western diet", exhibiting altered redox homeostasis, insulin resistance, and early mitochondrial alterations in the liver. Therefore, this type of dietary habits should be drastically limited to pursue a "healthy aging".

Metabolic Effects of the Sweet Protein MNEI as a Sweetener in Drinking Water. A Pilot Study of a High Fat Dietary Regimen in a Rodent Model.

Sweeteners have become integrating components of the typical western diet, in response to the spreading of sugar-related pathologies (diabetes, obesity and metabolic syndrome) that have stemmed from the adoption of unbalanced dietary habits. Sweet proteins are a relatively unstudied class of sweet compounds that could serve as innovative sweeteners, but their introduction on the food market has been delayed by some factors, among which is the lack of thorough metabolic and toxicological studies. We have tried to shed light on the potential of a sweet protein, MNEI, as a fructose substitute in beverages in a typical western diet, by studying the metabolic consequences of its consumption on a Wistar rat model of high fat diet-induced obesity. In particular, we investigated the lipid profile, insulin sensitivity and other indicators of metabolic syndrome. We also evaluated systemic inflammation and potential colon damage. MNEI consumption rescued the metabolic derangement elicited by the intake of fructose, namely insulin resistance, altered plasma lipid profile, colon inflammation and translocation of lipopolysaccharides from the gut lumen into the circulatory system. We concluded that MNEI could represent a valid alternative to fructose, particularly when concomitant metabolic disorders such as diabetes and/or glucose intolerance are present.

Bacillus megaterium SF185 spores exert protective effects against oxidative stress in vivo and in vitro.

Endogenous reactive oxygen species (ROS) are by-products of the aerobic metabolism of cells and have an important signalling role as secondary messengers in various physiological processes, including cell growth and development. However, the excessive production of ROS, as well as the exposure to exogenous ROS, can cause protein oxidation, lipid peroxidation and DNA damages leading to cell injuries. ROS accumulation has been associated to the development of health disorders such as neurodegenerative and cardiovascular diseases, inflammatory bowel disease and cancer. We report that spores of strain SF185, a human isolate of Bacillus megaterium, have antioxidant activity on Caco-2 cells exposed to hydrogen peroxide and on a murine model of dextran sodium sulfate-induced oxidative stress. In both model systems spores exert a protective state due to their scavenging action: on cells, spores reduce the amount of intracellular ROS, while in vivo the pre-treatment with spores protects mice from the chemically-induced damages. Overall, our results suggest that treatment with SF185 spores prevents or reduces the damages caused by oxidative stress. The human origin of SF185, its strong antioxidant activity, and its protective effects led to propose the spore of this strain as a new probiotic for gut health.

Effect of Initial Aging and High-Fat/High-Fructose Diet on Mitochondrial Bioenergetics and Oxidative Status in Rat Brain.

Middle age is an early stage of the aging process, during which the consumption of diets rich in saturated fats and/or simple sugars might influence brain function, but only few data are available on this issue. We therefore investigated the impact of a diet rich in saturated fat and fructose (HFF) on mitochondrial physiology in hippocampus and frontal cortex of middle-aged rats (1 year old), by including a group of adult rats (90 days) as a "negative control," lacking the putative effect of aging. Middle-aged rats were fed HFF or control diet for 4 weeks. Mitochondrial function was analyzed by high-resolution respirometry and by assessing the amount of respiratory complexes. Markers of oxidative balance, as well as the protein content of uncoupling protein 2 (UCP2), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and peroxisome proliferator-activated receptor alpha (PPARα), were also assessed. A decrease in the activity of complex I was detected in both brain areas of middle-aged rats. In hippocampus, mitochondrial respiratory capacity and complex IV content decreased with age and increased with HFF diet. Higher protein oxidative damage, decreased antioxidant defenses, and increased UCP2 and PGC-1α content were found in hippocampus of middle-aged rats. HFF feeding induced a significant reduction in the amount of UCP2, PGC-1α, and PPARα, together with higher protein oxidative damage, in both brain areas. Overall, our results point to middle age as a condition of early brain aging for mitochondrial function, with hippocampus being an area more susceptible to metabolic impairment than frontal cortex.

Insulin-Driven PI3K-AKT Signaling in the Hepatocyte Is Mediated by Redundant PI3Kα and PI3Kß Activities and Is Promoted by RAS.

Phosphatidylinositol-3-kinase (PI3K) activity is aberrant in tumors, and PI3K inhibitors are investigated as cancer therapeutics. PI3K signaling mediates insulin action in metabolism, but the role of PI3K isoforms in insulin signaling remains unresolved. Defining the role of PI3K isoforms in insulin signaling is necessary for a mechanistic understanding of insulin action and to develop PI3K inhibitors with optimal therapeutic index. We show that insulin-driven PI3K-AKT signaling depends on redundant PI3Kα and PI3Kß activities, whereas PI3Kδ and PI3Kγ are largely dispensable. We have also found that RAS activity promotes AKT phosphorylation in insulin-stimulated hepatocytes and that promotion of insulin-driven AKT phosphorylation by RAS depends on PI3Kα. These findings reveal the detailed mechanism by which insulin activates AKT, providing an improved mechanistic understanding of insulin signaling. This improved model for insulin signaling predicts that isoform-selective PI3K inhibitors discriminating between PI3Kα and PI3Kß should be dosed below their hyperglycemic threshold to achieve isoform selectivity.