The Antioxidant Effect of Dietary Bioactives Arises from the Interplay between the Physiology of the Host and the Gut Microbiota: Involvement of Short-Chain Fatty Acids.

The maintenance of redox homeostasis is associated with a healthy status while the disruption of this mechanism leads to the development of various pathological conditions. Bioactive molecules such as carbohydrates accessible to the microbiota (MACs), polyphenols, and polyunsaturated fatty acids (PUFAs) are food components best characterized for their beneficial effect on human health. In particular, increasing evidence suggests that their antioxidant ability is involved in the prevention of several human diseases. Some experimental data indicate that the activation of the nuclear factor 2-related erythroid 2 (Nrf2) pathway-the key mechanism in the maintenance of redox homeostasis-is involved in the beneficial effects exerted by the intake of PUFAs and polyphenols. However, it is known that the latter must be metabolized before becoming active and that the intestinal microbiota play a key role in the biotransformation of some ingested food components. In addition, recent studies, indicating the efficacy of the MACs, polyphenols, and PUFAs in increasing the microbial population with the ability to yield biologically active metabolites (e.g., polyphenol metabolites, short-chain fatty acids (SCFAs)), support the hypothesis that these factors are responsible for the antioxidant action on the physiology of the host. The underlying mechanisms through which MACs, polyphenols, and PUFAs might influence the redox status have not been fully elucidated, but based on the efficacy of SCFAs as Nrf2 activators, their contribution to the antioxidant efficacy of dietary bioactives cannot be excluded. In this review, we aimed to summarize the main mechanisms through which MACs, polyphenols, and PUFAs can modulate the host's redox homeostasis through their ability to directly or indirectly activate the Nrf2 pathway. We discuss their probiotic effects and the role played by the alteration of the metabolism/composition of the gut microbiota in the generation of potential Nrf2-ligands (e.g., SCFAs) in the host's redox homeostasis.

Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland).

Tsunamis occur not only in marine settings but also in lacustrine environments. Most of the lacustrine tsunamis are caused by seismically- or aseismically-triggered mass movements. Therefore, an assessment of the stability of subaqueous slopes is crucial for tsunami hazard assessment in a lake. We selected Lake Lucerne (Switzerland) as a natural laboratory to perform an in-depth geotechnical characterization of its subaqueous slopes. This lake experienced documented tsunamis in 1601 and 1687. Some of its slopes still bear sediment volumes with a potential for tsunamigenic failure. To identify such slopes, we interpreted available reflection seismic data and analyzed the bathymetric map. Then, we performed 152 dynamic Cone Penetration Tests with pore pressure measurement (CPTu) and retrieved 49 sediment cores at different locations in the lake. These data were used to characterize the failure-prone sediments and to evaluate the present-day static stability of subaqueous slopes. Obtained results allowed the definition of three classes of slopes in terms of static stability: unstable slopes, stable slopes close to the unstable state, and stable areas. Non-deltaic slopes with thicker unconsolidated fine-grained sediment drape and moderate-to-high slope gradients (> 5-10°) have the lowest Factor of Safety. In agreement with previous studies, the failure plane for the non-deltaic slopes is embedded within the fine-grained glaciolacustrine sediments. Deltaic slopes with prevailing coarse-grained sediments mostly appear statically stable. Finally, we generalized the measured undrained shear strength profiles s u ( z ) into the depth-dependent power-law models. These models define the s u of Lake Lucerne's sediments and can be applied to other lakes with similar sedimentation history. Supplementary Information: The online version contains supplementary material available at 10.1007/s11069-022-05310-1.

A Robust Workflow for Acquiring and Preprocessing Ambient Vibration Data from Small Aperture Ocean Bottom Seismometer Arrays to Extract Scholte and Love Waves Phase-Velocity Dispersion Curves.

The phase-velocity dispersion curve (DC) is an important characteristic of the propagation of surface waves in sedimentary environments. Although the procedure for DC estimation in onshore environments using ambient vibration recordings is well established, the DC estimation in offshore environments using Ocean Bottom Seismometers (OBS) array recordings of ambient vibrations presents three additional challenges: (1) the localization of sensors, (2) the orientation of the OBS horizontal components, and (3) the clock error. Here, we address these challenges in an inherent preprocessing workflow to ultimately extract the Love and Scholte wave DC from small aperture OBS array measurements performed between 2018 and 2020 in Lake Lucerne (Switzerland). The arrays have a maximum aperture of 679 m and a maximum deployment water depth of 81 m. The challenges related to the OBS location on the lake floor are addressed by combining the multibeam bathymetry map and the backscatter image for the investigated site with the differential GPS coordinates of the OBS at recovery. The OBS measurements are complemented by airgun surveys. Airgun data are first used to estimate the misorientation of the horizontal components of the OBS and second to estimate the clock error. To assess the robustness of the preprocessing workflow, we use two array processing methods, namely the three-component high-resolution frequency-wavenumber and the interferometric multichannel analysis of surface waves, to estimate the dispersion characteristics of the propagating Scholte and Love waves for one of the OBS array sites. The results show the effectiveness of the preprocessing workflow. We observe the phase-velocity dispersion curve branches in the frequency range between 1.2 and 3.2 Hz for both array processing techniques. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00024-021-02923-8.

Effects of a Lifestyle Change Intervention on Semen Quality in Healthy Young Men Living in Highly Polluted Areas in Italy: The FASt Randomized Controlled Trial.

BACKGROUND: Human semen quality is affected by lifestyle and environmental factors. OBJECTIVE: To evaluate the short-term effects of a diet and physical activity intervention on semen quality of healthy young men living in highly polluted areas of Italy. DESIGN, SETTING, AND PARTICIPANTS: A randomized controlled trial was conducted. Healthy young men were assigned to an intervention or a control group. INTERVENTION: A 4-mo Mediterranean diet and moderate physical activity program. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcomes were sperm concentration, motility and morphology, concentration of round cells, and semen total antioxidant capacity. Secondary outcomes were adherence to Mediterranean diet and physical activity. All outcomes were measured twice, at the enrollment (t0) and at the end of the intervention (t4). RESULTS AND LIMITATIONS: A total of 263 individuals attended all visits, and underwent examinations and laboratory analyses: 137 in the intervention group and 126 in the control group. The adherence to Mediterranean diet and physical activity level increased more in the intervention group than in the control group from t0 to t4. Sperm concentration, total and progressive motility, and proportion of normal morphology cells increased in the intervention group but decreased in the control group, with statistically significant differences between the two groups at t4. The total antioxidant capacity increased in the intervention group but decreased in the control group, from t0 to t4. CONCLUSIONS: Study results showed that an intervention based on Mediterranean diet and regular physical activity can determine an improvement of semen quality in healthy young men. PATIENT SUMMARY: Our study aimed to evaluate the effect of a lifestyle intervention on semen quality of healthy young men. We assigned the 263 enrolled individuals to an intervention or a control group. The intervention group followed a 4-mo Mediterranean diet and moderate physical activity program, at the end of which the participants showed an improvement of semen quality parameters.

Heart Mitochondrial Metabolic Flexibility and Redox Status Are Improved by Donkey and Human Milk Intake.

The biological mechanisms linking nutrition and antioxidants content of the diet with cardiovascular protection are subject of intense investigation. It has been demonstrated that dietary supplementation with cow, donkey or human milk, characterized by distinct nutritional properties, triggers significant differences in the metabolic and inflammatory status through the modulation of hepatic and skeletal muscle mitochondrial functions. Cardiac mitochondria play a key role for energy-demanding heart functions, and their disfunctions is leading to pathologies. Indeed, an altered heart mitochondrial function and the consequent increased reactive oxygen species (ROS) production and inflammatory state, is linked to several cardiac diseases such as hypertension and heart failure. In this work it was investigated the impact of the milk consumption on heart mitochondrial functions, inflammation and oxidative stress. In addition, it was underlined the crosstalk between mitochondrial metabolic flexibility, lipid storage and redox status as control mechanisms for the maintenance of cardiovascular health.

First morphological-level insights into the efficiency of green tea catechins and grape seed procyanidins on a transgenic mouse model of celiac disease enteropathy.

Alternative or complementary treatments to a gluten-free diet are urgently needed for Celiac Disease. By exploiting the health-promoting properties of polyphenols on a transgenic mouse model of Celiac Disease enteropathy, this study provides the first in vivo evidence regarding the ability of 1 mg day-1 doses of green tea catechins and grape seed procyanidins to ameliorate some of the most characteristic histological changes of gliadin-treated DQ8 mice, including villus flattening, crypt hyperplasia, and infiltration of intraepithelial lymphocytes. Mechanistically, polyphenols were found to increase the intestinal nucleophilic tone of DQ8 mice by orchestrating an adaptive antioxidant response characterized by enhanced GSR enzyme activity and GSH content. Taken together, this work constitutes a highly relevant breakthrough as it provides the fundamental basis concerning the significance of natural polyphenols to be used in, for instance, the development of innovative functional foods aimed at CD individuals.

Milk Fatty Acid Profiles in Different Animal Species: Focus on the Potential Effect of Selected PUFAs on Metabolism and Brain Functions.

Milk contains several important nutrients that are beneficial for human health. This review considers the nutritional qualities of essential fatty acids (FAs), especially omega-3 (ω-3) and omega-6 (ω-6) polyunsaturated fatty acids (PUFAs) present in milk from ruminant and non-ruminant species. In particular, the impact of milk fatty acids on metabolism is discussed, including its effects on the central nervous system. In addition, we presented data indicating how animal feeding-the main way to modify milk fat composition-may have a potential impact on human health, and how rearing and feeding systems strongly affect milk quality within the same animal species. Finally, we have presented the results of in vivo studies aimed at supporting the beneficial effects of milk FA intake in animal models, and the factors limiting their transferability to humans were discussed.

Modulatory role of dietary polyunsaturated fatty acids in Nrf2-mediated redox homeostasis.

Polyunsaturated fatty acids (PUFA) are fundamental building materials for cells and play crucial function as signaling molecules. When PUFA are used as substrates for non-enzymatic or enzymatic reactions and gut microbiota metabolism, they can generate electrophilic derivatives (called Reactive Lipid Species, RLS) that promptly form adducts with nucleophilic molecules. RLS participate in several signaling pathways, including the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, which is the key mechanism in the maintenance of redox, metabolic and protein homeostasis, as well as the regulation of inflammation. Recent studies have provided insights on the localization of enzymes that synthesise reactive oxygen or nitrogen species (ROS or RNS respectively) in plasma membrane compartments (raft/caveolae) which also harbour PUFA esters, from which free acid forms can be released by phospholipase A2 activity (PLA2), and the complex of Nrf2 with the inhibitory protein Kelch-like ECH-associated Protein 1(Keap1). Additional investigations have indicated that dietary PUFA insertion into specific plasma membrane microdomains may alter the lipid environment and thereby influence caveolar composition and cell signaling. Given that PUFA-originated RLS attack such a complex and promote the release of active Nrf2, it cannot be excluded that all the biochemical machinery for Nrf2 activation is present in caveolae, where it triggers the Nrf2-mediated adaptive response for rescuing or maintaining cellular redox homeostasis. Here, we specifically aimed to summarize current information with regard to the roles of dietary PUFA and RLS in Nrf2-mediated redox homeostasis, namely 1) their role as Nrf2 activators, 2) the significance of the in vivo conversion of PUFA into RLS and 3) the caveolar involvement in cell signaling for redox homeostasis.

The murine enterocyte cell line Mode-K is a novel and reliable in vitro model for studies on gluten toxicity.

The resemblance of physiological traits of cell lines with their target/original tissue is an important prerequisite for the choice of the in vitro model. Although cytoprotective defenses, activated by the nuclear factor erythroid 2-related factor2 (Nrf2), have a preeminent importance in intestinal protection, nevertheless their levels inin vitro models have been never compared with those of their original tissue. Basal level of Nrf2-mediated defenses in murine enterocyte cells (Mode-K) and in human colon adenocarcinoma cells -at differentiated (DCaco2) or confluent stage (CCaco2)- were compared with those found in mouse or human duodenum. The pro-oxidant and cytotoxic effects of peptic-tryptic digest of gluten prepared from wheat bread (PT-b), einkorn (PT-e) or durum wheat (PT-d) were evaluated in Mode-k and DCaco2 by combining enzymatic, immune-enzymatic and real-time PCR assay. The results presented reveal that Mode-k cells resemble cytoprotective defenses of human/murine duodenum and are more susceptible to pro-oxidant, cytotoxic and pro-inflammatory effect of gliadin digest (in comparison with Caco2). Prolamins digests from the considered wheat exhibit different inhibitory effect on Nrf2-mediated defenses (PT-b > PT-e > PT-d). These data indicate, for the first time, that Mode-k are a reliable model for investigating wheat prolamins toxicity and for evaluating the signaling pathway of gluten-associated disease.

Ginkgo biloba Prevents Oxidative Stress-Induced Apoptosis Blocking p53 Activation in Neuroblastoma Cells.

Oxidative stress has been associated to neuronal cell loss in neurodegenerative diseases. Neurons are post-mitotic cells that are very sensitive to oxidative stress-especially considering their limited capacity to be replaced. Therefore, reduction of oxidative stress, and inhibiting apoptosis, will potentially prevent neurodegeneration. In this study, we investigated the neuroprotective effect of Ginkgo biloba extract (EGb 761) against H2O2 induced apoptosis in SK-N-BE neuroblastoma cells. We analysed the molecular signalling pathway involved in the apoptotic cell death. H2O2 induced an increased acetylation of p53 lysine 382, a reduction in mitochondrial membrane potential, an increased BAX/Bcl-2 ratio and consequently increased Poly (ADP-ribose) polymerase (PARP) cleavage. All these effects were blocked by EGb 761 treatment. Thus, EGb 761, acting as intracellular antioxidant, protects neuroblastoma cells against activation of p53 mediated pathway and intrinsic mitochondrial apoptosis. Our results suggest that EGb 761, protecting against oxidative-stress induced apoptotic cell death, could potentially be used as nutraceutical for the prevention and treatment of neurodegenerative diseases.

Decreased Metabolic Flexibility in Skeletal Muscle of Rat Fed with a High-Fat Diet Is Recovered by Individual CLA Isomer Supplementation via Converging Protective Mechanisms.

Energy balance, mitochondrial dysfunction, obesity, and insulin resistance are disrupted by metabolic inflexibility while therapeutic interventions are associated with improved glucose/lipid metabolism in skeletal muscle. Conjugated linoleic acid mixture (CLA) exhibited anti-obesity and anti-diabetic effects; however, the modulatory ability of its isomers (cis9, trans11, C9; trans10, cis12, C10) on the metabolic flexibility in skeletal muscle remains to be demonstrated. Metabolic inflexibility was induced in rat by four weeks of feeding with a high-fat diet (HFD). At the end of this period, the beneficial effects of C9 or C10 on body lipid content, energy expenditure, pro-inflammatory cytokines, glucose metabolism, and mitochondrial efficiency were examined. Moreover, oxidative stress markers, fatty acids, palmitoyletanolamide (PEA), and oleyletanolamide (OEA) contents along with peroxisome proliferator-activated receptors-alpha (PPARα), AKT, and adenosine monophosphate-activated protein kinase (AMPK) expression were evaluated in skeletal muscle to investigate the underlying biochemical mechanisms. The presented results indicate that C9 intake reduced mitochondrial efficiency and oxidative stress and increased PEA and OEA levels more efficiently than C10 while the anti-inflammatory activity of C10, and its regulatory efficacy on glucose homeostasis are associated with modulation of the PPARα/AMPK/pAKT signaling pathway. Our results support the idea that the dissimilar efficacy of C9 and C10 against the HFD-induced metabolic inflexibility may be consequential to their ability to activate different molecular pathways.

Innate immunity is a late event in the onset of gliadin-specific enteropathy in the HLA-DQ8 mice.

Celiac disease (CD) is a food enteropathy that occurs in genetically susceptible individuals following the ingestion of gluten. Both gluten cytotoxicity and immunity activation play a role in CD pathogenesis; however, the chronological assessment of the different pathogenic mechanisms remains elusive. The models developed so far have only partially addressed this issue. Herein, Ab°DQ8 transgenic mice were administered wheat gliadin and indomethacin for 10 days to induce enteropathy. Gliadin-induced alteration of the small intestinal architecture was associated with increased expression of tissue transglutaminase in the lamina propria and a marked hypoxic environment. Enteropathic mice showed activation of innate immunity, featuring an increase of pro-inflammatory IFN-γ and IL-15 mRNAs, as well as CD11c+CD103+, CD11b+CD11c+, and CD11b+CD103+ dendritic cell subsets. However, the temporal assessment of examined parameters indicated that the induction of innate immunity during the generation of the mucosal lesion, occurred belatedly, highlighting a major role of gliadin intrinsic cytotoxicity in the pathogenic mechanism of this model. These results have important implications for the use of this model to test the impact of biotechnological interventions to reduce the cytotoxicity of gliadin.

Microbial transglutaminase: A biotechnological tool to manage gluten intolerance.

Celiac disease (CD) is a chronic immune-mediated disease in which gluten ingestion leads to damage of the small intestinal mucosa in genetically susceptible individuals. The enteropathy is mainly induced by the production of IFN-γ from intestinal CD4+T cells that recognise gliadin peptides following deamidation by tissue transglutaminase. The only available therapy is a strict, lifelong gluten-free diet (GFD). This diet is strongly demanding for patients, which justifies the search for alternative strategies. The enzyme approach is one promising strategy to address this issue. In particular, transamidation of wheat gliadin by microbial transglutaminase (mTG) was fully effective at inhibiting gliadin-specific IFN-γ secretion in intestinal T cells from CD patients. Furthermore, transamidated gliadin induced higher levels of the anti-inflammatory IL-10 than native gliadin in different in vitro models. These data suggest that a more balanced immune response could be induced by mTG-treated gliadin in the small intestine of celiac patients. Furthermore, the highlighted biological property of mTG-treated gliadin could be exploited to induce tolerance to native gliadin in at-risk individuals.

Brain Nrf2 pathway, autophagy, and synaptic function proteins are modulated by a short-term fructose feeding in young and adult rats.

Objectives: A strong rise of the fructose content in the human diet occurred in the last decade, as corn syrup is widely used as a sweetener for beverages and processed food. Since young people make a widespread consumption of added sugars, we evaluated the effects of a two weeks fructose-rich diet on brain redox homeostasis, autophagy and synaptic plasticity in the cortex of young and adults rats, in order to highlight the early risks to which brain is exposed.Methods and Results: Short-term fructose feeding was associated with an imbalance of redox homeostasis, as lower amount of Nuclear factor (erythroid derived 2)-like 2, lower activity of Glucose 6-phosphate dehydrogenase and Glutathione reductase, together with lower Glutathione/Oxidized Glutathione ratio, were found in fructose-fed young and adult rats. Fructose-rich diet was also associated with the activation of autophagy, as higher levels of Beclin, LC3 II and P62 were detected in cortex of fructose-fed rats. A diet associated decrease of synaptophysin, synapsin I, and synaptotagmin I, was found in fructose-fed young and adult rats. Interestingly, BDNF amount was significantly lower only in fructose-fed adult rats, while the level of its receptor TrkB decreased in both groups of treated rats. A further marker of brain functioning, Acetylcholinesterase activity, was found increased only in fructose-fed young animals.Conclusion: Overall, our findings suggest that young rats may severely suffer from the deleterious influence of fructose on brain health as the adults and provide experimental data suggesting the need of targeted nutritional strategies to reduce its amount in foods.

Crosstalk between mitochondrial metabolism and oxidoreductive homeostasis: a new perspective for understanding the effects of bioactive dietary compounds.

Mitochondria play an important role in a number of fundamental cellular processes, including energy production, biosynthetic pathways and cellular oxidoreductive homeostasis (redox status), and their dysfunction can lead to numerous pathophysiological consequences. As the biochemical mechanisms orchestrating mitochondrial metabolism and redox homeostasis are functionally linked, mitochondria have been identified as a potential therapeutic target. Consequently, considerable effort has been made to evaluate the efficacy of natural compounds that modulate mitochondrial function. Molecules produced by plants (for example, polyphenols and isothiocyanates) have been shown to modulate mitochondrial metabolism/biogenesis and redox status; however, despite the existence of a functional link, few studies have considered the combined efficacy of these mitochondrial functions. The present review provides a complete overview of the molecular pathways involved in modulating mitochondrial metabolism/biogenesis and redox status. Crosstalk between these critical mechanisms is also discussed, whilst major data from the literature regarding their antioxidant abilities are described and critically analysed. We also provide a summary of recent evidence regarding the ability of several plant-derived compounds to target these mitochondrial functions. An in-depth understanding of the functional link between mitochondrial metabolism/biogenesis and redox status could facilitate the analysis of the biological effects of natural compounds as well as the development of new therapeutic approaches.

Prunus Mahaleb Fruit Extract Prevents Chemically Induced Colitis and Enhances Mitochondrial Oxidative Metabolism via the Activation of the Nrf2 Pathway.

SCOPE: Polyphenols exhibit their antioxidant activity downstream the activation of the nuclear factor erythroid 2-related factor 2 pathway (Nrf2), but the connection between lipid metabolism and the Nrf2 pathway is still unknown. Flavonoid-rich concentrated extract from Prunus mahaleb (mahaleb concentrated fruit extract; MCFE) may act on oxido-reductive homeostasis and hepatic lipid metabolism via Nrf2. METHODS & RESULTS: MCFE ability to enhance the activity of Nrf2-mediated antioxidant/detoxifying enzymes is investigated in liver and colon of BALB/c mice. After a 4-week supplementation, macroscopic, histological, and biochemical signs of colitis are examined in mouse colon pulsed with 5% (w/v) dextran sodium sulfate (DSS). Untreated or DSS-supplemented mice are used as negative or positive control. MCFE effect on liver lipid metabolism and its possible link with the Nrf2 pathway is investigated. MCFE intake increases antioxidant defenses in mice colon and its pretreatment blunts pathological signs of colitis, as compared to positive control. In the liver, the increase in antioxidant defenses is associated with enhanced oxidative metabolism and with higher levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and of hemeoxygenase-1 (HO-1), in comparison with negative controls. CONCLUSION: Cytoprotective and hypolipidemic effect produced by MCFE intake results, at least in part, by the activation of the Nrf2 pathway.

Dietary Supplementation with Fish Oil or Conjugated Linoleic Acid Relieves Depression Markers in Mice by Modulation of the Nrf2 Pathway.

Inflammation and oxidative stress play an important role in the pathogenesis of depressive disorders and nuclear erythroid related factor 2 (Nrf2), a regulator of RedOx homeostasis and inflammation, is a promising target for depression prevention/treatment. As fish oil (FO) and conjugated linoleic acid (CLA) are known Nrf2 inducers, their protective ability is comparatively evaluated in a murine model of depression (MRL/MpJ-Faslpr ). Oxidative stress, fatty acids content, and critical factors reflecting brain functioning-namely brain-derived neurotrophic factor (BDNF), synaptic markers, and cholinergic signaling-are preliminarily evaluated in the frontal cortex of 8-week (Young) and in 22-week old animals (Old), which are used as model of depression. These markers are measured in Old mice at the end of a 5-week pretreatment with FO or CLA (728 or 650 mg kg-1 , respectively). Old mice exhibit disrupted Redox homeostasis, compensatory Nrf2 hyperactivation, lower docosaheaxaenoic acid (DHA), and lower BDNF and synaptic function proteins compared to Young mice. FO and CLA treatment relieves almost all the pathophysiological hallmarks at a level comparable to Young mice. Presented data provide the first evidence for the comparable efficacy of FO or CLA supplementation in preventing depression signs in Old MRL/lpr mice, likely through their ability of improving Nrf2-mediated antioxidant defenses.

Conjugated linoleic acid prevents age-dependent neurodegeneration in a mouse model of neuropsychiatric lupus via the activation of an adaptive response.

Oxidative stress is a key mediator of autoimmune/neurodegenerative disorders. The antioxidant/anti-inflammatory effect of a synthetic conjugated linoleic acid (CLA) mixture in MRL/MpJ-Fas lpr mice (MRL/lpr), an animal model of neuropsychiatric lupus, was previously associated with the improvement of nuclear factor-E2-related factor 2 (Nrf2) defenses in the spleen and liver. However, little is known about the neuroprotective ability of a CLA mixture. This study investigated the age-dependent progression of oxidative stress and the hyperactivation of redox-sensitive compensatory pathways (macroautophagy, Nrf2) in old/diseased MRL/lpr mice brains and examines the effect produced by dietary CLA supplementation. Disrupted redox homeostasis was evidenced in the blood, liver, and brain of 21- to 22-week-old MRL/lpr (Old) mice compared with 8- to 10-week-old MRL/lpr (Young) animals. This alteration was associated with significant hyperactivation of compensatory mechanisms (macroautophagy, Nrf2, and astrocyte activation) in the brains of Old mice. Five-week daily supplementation with CLA (650 mg/kg-1 body weight) of 16-week-old (CLA+Old) mice diminished all the pathological hallmarks at a level comparable to Young mice or healthy controls (BALB/c). Such data demonstrated that MRL/lpr mice can serve as a valuable model for the evaluation of the effectiveness of neuroprotective drugs. Notably, the preventive effect provided by CLA supplementation against age-associated neuronal damage and hyperactivation of compensatory mechanisms suggests that the activation of an adaptive response is at least in part accountable for its neuroprotective ability.

Immunomodulatory activity of recombinant α-gliadin conjugated to cholera toxin in DQ8 transgenic mice.

Coeliac disease (CD) is characterized by an intestinal lesion sustained by an abnormal mucosal T-cell response to wheat gliadin. An immunological approach that is able to suppress this immune response is a perspective worth pursuing. Several strategies of antigen administration have been aimed at the downregulation of pathogenic T-cells. In particular, we previously reported a significant suppression of the systemic cell-mediated response toward wheat gliadin in DQ8 transgenic mice receiving nasally a recombinant α-gliadin. To gain further insight about the cellular mechanisms underlying the tolerogenic properties of this molecule, we analysed different preparations of the recombinant α-gliadin, alone or conjugated to the adjuvant cholera toxin (CT), by in vitro challenge with spleen CD4+ T cells from gliadin-sensitized DQ8 tg mice. We found that a partially purified preparation of recombinant α-gliadin (r-gliadin) induced a significantly higher production of IFN-γ than native gliadin as well as HPLC purified r-gliadin. Interestingly, r-gliadin, but not HPLC purified r-gliadin, stimulated the gliadin-specific expression of IL-10 in CD4+ T cells. No significant cytotoxic effect was induced by r-gliadin in MODE-K cells, a murine model of enterocytes. Notably, a conjugate CT-r-gliadin failed in stimulating IFN-γ, whereas IL-10 secretion was still induced in gliadin-specific CD4+ T cells. In conclusion, our results showed that DCs, pulsed with CT-r-gliadin in vitro, could modulate the ongoing Th1-like T cell response toward wheat gliadin. This finding provides new insight into the design of immunomodulatory protocols potentially useful for CD.

Modulation of the cytokine profile in Caco-2 cells by faecal lactobacilli and bifidobacteria from individuals with distinct dietary habits.

Enterocytes are actively involved in the defense against pathogens and they limit penetration of commensal microbes into tissues. They also have an important role in gut immunity as enterocytes confer mucosal dendritic cell specialisation. On the other hand, the microbiota is directly involved in the development and modulation of the intestinal immune system. Particularly, lactobacilli and bifidobacteria play a primary role in shaping the immune response. We further explored this issue by evaluating whether functional differences in Caco-2 cells could characterise faecal populations of lactobacilli (155 samples) and bifidobacteria (110 samples) isolated from three dietary cohorts (omnivores, ovo-lacto-vegetarians and vegans) recruited at four Italian centres (Turin, Parma, Bologna and Bari). According to our findings, tested bacteria were unable to modulate expression of IL-8, IL-10, TGF-ß or thymic stromal lymphopoietin (TSLP) cytokines in unstimulated Caco-2 cells. Conversely, in phorbol 12-myristate 13-acetate and ionomycin (PMA/Io) stimulated Caco-2 cells, lactobacilli from the omnivorous group and all bifidobacteria significantly down-regulated IL-8. Notably, both genera also lowered the TSLP expression in stimulated Caco-2 cells, regardless of the diet regimen. By further examining these data on the basis of geographical origin, we found that lactobacilli from the vegetarian group recruited in Bari, significantly up-regulated this cytokine. In conclusion, we highlighted a peculiar immune-modulatory activity profile for lactobacilli on enterocytes undergoing a stimulatory signal, which was associated with a specific dietary habit. Furthermore, the geographical area had a significant impact on the inflammatory potential of members of the Lactobacillus genus.