Dietary restriction and immune function

Growth performance, behavior, gene expression, carcass characteristics, stress indicators, and economical parameters of avian 48 broiler chickens raised under three different stocking density

The current research evaluated the consequence of varying stocking densities on growth performance, carcass features, hematological, welfare, economic parameters, and immune markers of broiler chicks. A total of 324 Avian 48 were haphazardly classified into three different stocking densities. There were 14 birds/m2 in the low stocking density (LSD) group, 18 birds/m2 in the medium stocking density (MSD) group, and 22 in the high stocking density (HSD) group. Compared to the other two groups, the HSD birds' body weight and daily weight gain were significantly lower (p < 0.05). The LSD group demonstrated a significant increase in productive efficiency (EPEF and EBI) compared to the medium and high SD groups (p < 0.003). The birds from the HSD group exhibited the lowest values for carcass characteristics compared to the low and medium SD groups. At the hematological level, the HSD group exhibited significantly elevated levels of HB, RBCs, heterophils, and lymphocytes compared to the LSD and MSD groups (p < 0.011, p < 0.0001, and p < 0.0001), respectively. Compared to the LSD group, the levels of cortisol, a hallmark of oxidative stress, were considerably greater in the MSD and HSD groups (p < 0.0001). Concerning gene expression, the birds in the LSD group exhibited a significant improvement in growth, intestinal health, and anti-inflammatory genes compared to the MSD and HSD groups. In addition, inflammatory markers were significantly downregulated. The HSD group exhibited the lowest net profit compared to the other groups (p < 0.0001). At the behavioral level, birds in the LSD group demonstrated a significantly shorter TI duration (p < 0.0001) and latency (p < 0.043) in OFT to the first step, lower mobility duration (p < 0.004), and pecking (p < 0.05) compared to other groups. Our study concluded that rearing in LSD up to MSD could be applied without compromising broiler performance.

Costs and constraints of cellular immune activity during development in an arboreal primate

Evolutionary life history theory predicts that, during development, investment in immunity must be balanced with the demands of growth. How, and at what time scales, this balance is negotiated is unclear. In this study, we examined the potential energetic costs and limitations to cellular immune activity during development, its trade-offs with growth, related sickness behaviour and the role of hypothalamic-pituitary-adrenal (HPA) axis activity in these relationships. We combined biomarker and socio-environmental data on wild juvenile blue monkeys collected over eight months. Rather than detract from energy balance (C-peptide) and growth of lean body mass (creatinine by specific gravity residuals), cellular immune activity (neopterin) increased with energy balance and lean body mass at monthly time scales, suggesting an energetic constraint on cellular immunity. At shorter time scales, higher neopterin diminished subsequent growth. Energetic constraints on immune activity were weakly regulated by HPA activity during low energy states. Our results suggest that cellular immune activity is both costly and limited by physical condition in wild developing primates.

Dynamic O-GlcNAcylation governs long-range chromatin interactions in V(D)J recombination during early B-cell development

V(D)J recombination secures the production of functional immunoglobulin (Ig) genes and antibody diversity during the early stages of B-cell development through long-distance interactions mediated by cis-regulatory elements and trans-acting factors. O-GlcNAcylation is a dynamic and reversible posttranslational modification of nuclear and cytoplasmic proteins that regulates various protein functions, including DNA-binding affinity and protein-protein interactions. However, the effects of O-GlcNAcylation on proteins involved in V(D)J recombination remain largely unknown. To elucidate this relationship, we downregulated O-GlcNAcylation in a mouse model by administering an O-GlcNAc inhibitor or restricting the consumption of a regular diet. Interestingly, the inhibition of O-GlcNAcylation in mice severely impaired Ig heavy-chain (IgH) gene rearrangement. We identified several factors crucial for V(D)J recombination, including YY1, CTCF, SMC1, and SMC3, as direct targets of O-GlcNAc modification. Importantly, O-GlcNAcylation regulates the physical interaction between SMC1 and SMC3 and the DNA-binding patterns of YY1 at the IgH gene locus. Moreover, O-GlcNAc inhibition downregulated DDX5 protein expression, affecting the functional association of CTCF with its DNA-binding sites at the IgH locus. Our results showed that locus contraction and long-range interactions throughout the IgH locus are disrupted in a manner dependent on the cellular O-GlcNAc level. In this study, we established that V(D)J recombination relies on the O-GlcNAc status of stage-specific proteins during early B-cell development and identified O-GlcNAc-dependent mechanisms as new regulatory components for the development of a diverse antibody repertoire.

Diet Change Improves Obesity and Lipid Deposition in High-Fat Diet-Induced Mice

The number of obese people is increasing dramatically worldwide, and one of the major causes of obesity is excess energy due to high-fat diets. Several studies have shown that reducing food and energy intake represents a key intervention or treatment to combat overweight/obesity. Here, we conducted a 12-week energy-restricted dietary intervention for high-fat diet-induced obese mice (C57BL/6J) to investigate the effectiveness of diet change in improving obesity. The results revealed that the diet change from HFD to NFD significantly reduced weight gain and subcutaneous adipose tissue weight in high-fat diet-induced obese mice, providing scientific evidence for the effectiveness of diet change in improving body weight and fat deposition in obese individuals. Regarding the potential explanations for these observations, weight reduction may be attributed to the excessive enlargement of adipocytes in the white adipose tissue of obese mice that were inhibited. Diet change significantly promoted lipolysis in the adipose tissue (eWAT: Adrb3, Plin1, HSL, and CPTA1a; ingWAT: CPT1a) and liver (reduced content of nonesterified fatty acids), and reduced lipogenesis in ingWAT (Dgat2). Moreover, the proportion of proliferative stem cells in vWAT and sWAT changed dramatically with diet change. Overall, our study reveals the phenotypic, structural, and metabolic diversity of multiple tissues (vWAT and sWAT) in response to diet change and identifies a role for adipocyte stem cells in the tissue specificity of diet change.

Programmed ageing: decline of stem cell renewal, immunosenescence, and Alzheimer's disease

The characteristic maximum lifespan varies enormously across animal species from a few hours to hundreds of years. This argues that maximum lifespan, and the ageing process that itself dictates lifespan, are to a large extent genetically determined. Although controversial, this is supported by firm evidence that semelparous species display evolutionarily programmed ageing in response to reproductive and environmental cues. Parabiosis experiments reveal that ageing is orchestrated systemically through the circulation, accompanied by programmed changes in hormone levels across a lifetime. This implies that, like the circadian and circannual clocks, there is a master 'clock of age' (circavital clock) located in the limbic brain of mammals that modulates systemic changes in growth factor and hormone secretion over the lifespan, as well as systemic alterations in gene expression as revealed by genomic methylation analysis. Studies on accelerated ageing in mice, as well as human longevity genes, converge on evolutionarily conserved fibroblast growth factors (FGFs) and their receptors, including KLOTHO, as well as insulin-like growth factors (IGFs) and steroid hormones, as key players mediating the systemic effects of ageing. Age-related changes in these and multiple other factors are inferred to cause a progressive decline in tissue maintenance through failure of stem cell replenishment. This most severely affects the immune system, which requires constant renewal from bone marrow stem cells. Age-related immune decline increases risk of infection whereas lifespan can be extended in germfree animals. This and other evidence suggests that infection is the major cause of death in higher organisms. Immune decline is also associated with age-related diseases. Taking the example of Alzheimer's disease (AD), we assess the evidence that AD is caused by immunosenescence and infection. The signature protein of AD brain, Aβ, is now known to be an antimicrobial peptide, and Aβ deposits in AD brain may be a response to infection rather than a cause of disease. Because some cognitively normal elderly individuals show extensive neuropathology, we argue that the location of the pathology is crucial - specifically, lesions to limbic brain are likely to accentuate immunosenescence, and could thus underlie a vicious cycle of accelerated immune decline and microbial proliferation that culminates in AD. This general model may extend to other age-related diseases, and we propose a general paradigm of organismal senescence in which declining stem cell proliferation leads to programmed immunosenescence and mortality.

Rapamycin not dietary restriction improves resilience against pathogens: a meta-analysis

Dietary restriction (DR) and rapamycin both increase lifespan across a number of taxa. Despite this positive effect on lifespan and other aspects of health, reductions in some physiological functions have been reported for DR, and rapamycin has been used as an immunosuppressant. Perhaps surprisingly, both interventions have been suggested to improve immune function and delay immunosenescence. The immune system is complex and consists of many components. Therefore, arguably, the most holistic measurement of immune function is survival from an acute pathogenic infection. We reanalysed published post-infection short-term survival data of mice (n = 1223 from 23 studies comprising 46 effect sizes involving DR (n = 17) and rapamycin treatment (n = 29) and analysed these results using meta-analysis. Rapamycin treatment significantly increased post infection survival rate (lnHR =  - 0.72; CI =  - 1.17, -0.28; p = 0.0015). In contrast, DR reduced post-infection survival (lnHR = 0.80; CI = 0.08, 1.52; p = 0.03). Importantly, the overall effect size of rapamycin treatment was significantly lower (p < 0.001) than the estimate from DR studies, suggesting opposite effects on immune function. Our results show that immunomodulation caused by rapamycin treatment is beneficial to the survival from acute infection. For DR, our results are based on a smaller number of studies, but do warrant caution as they indicate possible immune costs of DR. Our quantitative synthesis suggests that the geroprotective effects of rapamycin extend to the immune system and warrants further clinical trials of rapamycin to boost immunity in humans.

Life factors acting on systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a highly heterogeneous autoimmune disease that primarily affects women. Currently, in the search for the mechanisms of SLE pathogenesis, the association of lifestyle factors such as diet, cigarette smoking, ultraviolet radiation exposure, alcohol and caffeine-rich beverage consumption with SLE susceptibility has been systematically investigated. The cellular and molecular mechanisms mediating lifestyle effects on SLE occurrence, including interactions between genetic risk loci and environment, epigenetic changes, immune dysfunction, hyper-inflammatory response, and cytotoxicity, have been proposed. In the present review of the reports published in reputable peer-reviewed journals and government websites, we consider the current knowledge about the relationships between lifestyle factors and SLE incidence and outline directions of future research in this area. Formulation of practical measures with regard to the lifestyle in the future will benefit SLE patients and may provide potential therapy strategies.

Long-term caloric restriction ameliorates T cell immunosenescence in mice

Aging is associated with a decrease in the function of the immune system, a phenomenon known as immunosenescence, which results in reduced resistance to infection. Caloric restriction (CR) is known to prolong lifespan and to regulate immune function. However, whether and how CR affects immunosenescence remains unclear. Here, we evaluated the effect of long- and short-term CR on immunosenescence by subjecting wild-type mice to CR between 6 and 18 months of age or between 17 and 18 months of age, respectively. Compared with a normal diet or short-term CR, long-term CR induced marked or complete attenuation of age-related decreases in the frequency of spleen NK cells and NKT cells; naïve CD4⁺ and CD8⁺ T cells; and cytokine- and granzyme B-secreting T cells. In contrast, both long- and short-term CR significantly suppressed age-related upregulation of the T cell exhaustion markers PD-1, Tim-3, and KLRG1, as well as the transcription factors NR4A1 and TOX, which regulate the expression of genes associated with the T cell exhaustion phenotype. These results suggest that CR might suppress age-associated immunosenescence by regulating the expression of transcription factors and target genes that control T cell exhaustion.

Probiotic Consumption Boosts Thymus in Obesity and Senescence Mouse Models

The ability of the immune system to respond to different pathogens throughout life requires the constant production and selection of T cells in the thymus. This immune organ is very sensitive to age, infectious processes and nutrition disorders (obesity and malnutrition). Several studies have shown that the incorporation of some probiotic bacteria or probiotic fermented milk in the diet has beneficial effects, not only at the intestinal level but also on distant mucosal tissues, improving the architecture of the thymus in a malnutrition model. The aim of the present study was to determine whether supplementation with the probiotic strain Lactobacillus casei CRL 431 and/or its cell wall could improve body weight, intestinal microbiota and thymus structure and function in both obese and aging mice. We evaluated probiotic administration to BALB/c mice in 2 experimental mouse models: obesity and senescence, including mice of different ages (21, 28, 45, 90 and 180 days). Changes in thymus size and histology were recorded. T-lymphocyte population and cytokine production were also determined. The consumption of probiotics improved the cortical/medullary ratio, the production and regulation of cytokines and the recovery of mature T-lymphocyte populations of the thymus in obese and old mice. Probiotic incorporation into the diet could not only modulate the immune system but also lead to thymus function recovery, thus improving quality of life.

Protective Features of Calorie Restriction on Cuprizone-induced Demyelination via Modulating Microglial Phenotype

Multiple sclerosis (MS) is an immune-mediated demyelinating disorder in the central nervous system (CNS) with no definitive treatment, but it can be alleviated by changing life habits. Calorie restriction (CR) is effective in preventing or treating metabolic and autoimmune disorders. CR is one of the helpful approaches to control the progression of MS. In the present study, we investigated the preventive effect of caloric restriction on cuprizone induced-demyelination, a model of multiple sclerosis. To induce acute demyelination in C57/BL6 mice, we added 0.2% Cuprizone (CPZ) to their diet for 6 weeks. To induce calorie restriction, 10% Carboxymethyl cellulose (CMC) was added to the diet as a dietary cellulose fiber for 6 weeks. Remyelination was studied by luxol fast blue (LFB) staining. Microglia activity, M1 and M2 microglial/macrophage phenotypes were assessed by immunohistochemistry of Iba-1, iNOS and Arg-1, respectively. The expression of targeted genes was assessed by the real-time polymerase chain reaction. Luxol fast blue (LFB) staining showed that the CR regimen could decrease the cuprizone-induced demyelination process (p < 0.01). Moreover, the CR application could improve balance and motor performance in cuprizone-intoxicated mice by significantly enhancing protein and gene expression of Sirt1, M2 microglial phenotype marker (Arg-1) and Akt1 gene expression, also decreased M1 microglial phenotype marker (iNOS), Akt2 and P53 gene expressions (p < 0.05). Cumulatively, it can be concluded that caloric restriction was able to counteract MS symptoms through alleviating inflammatory responses.

Effects of different stocking densities on tracheal barrier function and its metabolic changes in finishing broilers

In the present study, we evaluated the effects of various stocking densities on the tracheal barrier and plasma metabolic profiles of finishing broilers. We randomly assigned 1,440 Lingnan Yellow feathered broilers (age 22 d) to 5 different stocking density groups (8 m-2, 10 m-2, 12 m-2, 14 m-2, and 16 m-2). Each of these consisted of 3 replicates. The interleukin (IL)-1β and IL-10 concentrations were substantially higher in the 16 m-2 treatment group than they were in the 8 m-2 and 10 m-2 treatment groups (P < 0.05). Nevertheless, IL-4 did not significantly differ among the 5 treatments (P > 0.05). The tracheal mucosae of the birds in the 16 m-2 group (high stocking density, HSD) were considerably thicker than those for the birds in the 10 m-2 group (control, CSD). Relative to CSD, the claudin1 expression level was lower, and the muc2 and caspase3 expression levels were higher for HSD. Compared with CSD, 10 metabolites were significantly upregulated (P < 0.05), and 7 were significantly downregulated (P < 0.05) in HSD. Most of these putative diagnostic biomarkers were implicated in matter biosynthesis and energy metabolism. A metabolic pathway analysis revealed that the most relevant and critical biomarkers were pentose and glucuronate interconversions and the pentose phosphate pathway. Activation of the aforementioned pathways may partially counteract the adverse effects of the stress induced by high stocking density. This work helped improve our understanding of the harmful effects of high stocking density on the tracheal barrier and identified 2 metabolic pathways that might be associated with high stocking density-induced metabolic disorders in broilers.

Age-related mitochondrial dysfunction as a key factor in COVID-19 disease

SARS-CoV-2 causes a severe pneumonia (COVID-19) that affects essentially elderly people. In COVID-19, macrophage infiltration into the lung causes a rapid and intense cytokine storm leading finally to a multi-organ failure and death. Comorbidities such as metabolic syndrome, obesity, type 2 diabetes, lung and cardiovascular diseases, all of them age-associated diseases, increase the severity and lethality of COVID-19. Mitochondrial dysfunction is one of the hallmarks of aging and COVID-19 risk factors. Dysfunctional mitochondria is associated with defective immunological response to viral infections and chronic inflammation. This review discuss how mitochondrial dysfunction is associated with defective immune response in aging and different age-related diseases, and with many of the comorbidities associated with poor prognosis in the progression of COVID-19. We suggest here that chronic inflammation caused by mitochondrial dysfunction is responsible of the explosive release of inflammatory cytokines causing severe pneumonia, multi-organ failure and finally death in COVID-19 patients. Preventive treatments based on therapies improving mitochondrial turnover, dynamics and activity would be essential to protect against COVID-19 severity.

The impact of varying food availability on health and welfare in mice: Testing the Match-Mismatch hypothesis

During early phases of life, an organism's phenotype can be shaped by the environmental conditions which it experiences. If the conditions change subsequently, the mismatch between the environment in early and later life could have negative effects on the individual's health and welfare. The aim of this study was to systematically test the predictions of this Match-Mismatch hypothesis in laboratory mice. Therefore, female C57BL/6 J mice were exposed to matching or mismatching combinations of low and high food availability in adolescence and early adulthood. A comprehensive analysis of various physiological and behavioral parameters was conducted. No indication of a mismatch effect was found, which might be attributed to the specific ecology of mice. Alternatively, food availability might cause a shaping of the phenotype only during the prenatal or early postnatal development. However, various effects of low vs high food availability were found regarding the individuals' physiology and, to a small extent, their behavior. Low food availability caused higher concentrations of fecal corticosterone metabolites, as well as higher liver and lower spleen weights, suggesting an adaptation of the metabolism to this situation.

Methionine increases yolk production to offset the negative effect of caloric restriction on reproduction without affecting longevity in C. elegans

Caloric restriction (CR) or Dietary restriction (DR) is known to improve health and in many cases increases lifespan. However, its negative effect on reproduction has not been fully studied. Practicing CR/DR without adequate knowledge on its side effect may risk complications such as infertility, birth defect, or malnutrition. In this study, by using several CR strategies in C. elegans, we examine key functions of reproduction including embryonic development and larvae growth. We find that CR significantly decreases the survival of embryos and slows the growth of the offspring. We further determine that defect in oocyte but not sperm is responsible for the compromised reproduction under CR. Interestingly, adding methionine to the medium reverses the reproduction defects, but does not affect the long lifespan resulted from CR. The beneficial effect of methionine on reproduction requires the yolk protein vitellogenin. CR down-regulates vitellogenin expression, which can be reversed by supplementing methionine in the food. Lacking the yolk protein transport due to rme-2 mutation blocks methionine’s beneficial effects. Our study has revealed a novel, methionine-mediated genetic pathway linking nutrient sensing to reproduction and suggested methionine as a potential food supplement to mitigate the side effect of CR.

Molecular Pathways Mediating Immunosuppression in Response to Prolonged Intensive Physical Training, Low-Energy Availability, and Intensive Weight Loss

Exercise and exercise-induced weight loss have a beneficial effect on overall health, including positive effects on molecular pathways associated with immune function, especially in overweight individuals. The main aim of our study was to assess how energy deprivation (i.e., “semi-starvation”) leading to substantial fat mass loss affects the immune system and immunosuppression in previously normal weight individuals. Thus, to address this hypothesis, we applied a high-throughput systems biology approach to better characterize potential key pathways associated with immune system modulation during intensive weight loss and subsequent weight regain. We examined 42 healthy female physique athletes (age 27.5 ± 4.0 years, body mass index 23.4 ± 1.7 kg/m²) volunteered into either a diet group (n = 25) or a control group (n = 17). For the diet group, the energy intake was reduced and exercise levels were increased to induce loss of fat mass that was subsequently regained during a recovery period. The control group was instructed to maintain their typical lifestyle, exercise levels, and energy intake at a constant level. For quantification of systems biology markers, fasting blood samples were drawn at three time points: baseline (PRE), at the end of the weight loss period (MID 21.1 ± 3.1 weeks after PRE), and at the end of the weight regain period (POST 18.4 ± 2.9 weeks after MID). In contrast to the control group, the diet group showed significant (false discovery rate <0.05) alteration of all measured immune function parameters—white blood cells (WBCs), immunoglobulin G glycome, leukocyte transcriptome, and cytokine profile. Integrative omics suggested effects on multiple levels of immune system as dysregulated hematopoiesis, suppressed immune cell proliferation, attenuated systemic inflammation, and loss of immune cell function by reduced antibody and chemokine secretion was implied after intense weight loss. During the weight regain period, the majority of the measured immune system parameters returned back to the baseline. In summary, this study elucidated a number of molecular pathways presumably explaining immunosuppression in individuals going through prolonged periods of intense training with low-energy availability. Our findings also reinforce the perception that the way in which weight loss is achieved (i.e., dietary restriction, exercise, or both) has a distinct effect on how the immune system is modulated.

Metabolic Alterations in Aging Macrophages: Ingredients for Inflammaging?

Aging is a complex process with an impact on essentially all organs. Declined cellular repair causes increased damage at genomic and proteomic levels upon aging. This can lead to systemic changes in metabolism and pro-inflammatory cytokine production, resulting in low-grade inflammation, or 'inflammaging'. Tissue macrophages, gatekeepers of parenchymal homeostasis and integrity, are prime inflammatory cytokine producers, as well as initiators and regulators of inflammation. In this opinion piece, we summarize intrinsic alterations in macrophage phenotype and function with age. We propose that alternatively activated macrophages (M2-like), which are yet pro-inflammatory, can accumulate in tissues and promote inflammaging. Age-related increases in endoplasmic reticulum stress and mitochondrial dysfunction might be cell-intrinsic forces driving this unusual phenotype.

Trade-Offs Underwater: Physiological Plasticity of Rainbow Trout (Oncorhynchus mykiss) Confronted by Multiple Stressors

Organisms have evolved mechanisms to partition the available resources between fitness-relevant physiological functions. Organisms possess phenotypic plasticity to acclimate to changing environmental conditions. However, this comes at a cost that can cause negative correlations or “trade-offs”, whereby increasing investments in one function lead to decreased investments in another function. The aim of the present study was to investigate the prioritization of resource allocation between growth, pathogen defense, and contaminant response in juvenile rainbow trout (Oncorhynchus mykiss) exposed to changes of resource income or expenditure. We performed a multifactorial experiment with three resource-impacting stressors—limited food availability, a parasitic infection, exposure to a vitellogenesis-inducing contaminant—and combinations thereof. Treatment with the individual stressors evoked the expected responses in the respective physiological target systems—body growth, immune system, and hepatic vitellogenin transcription—but we found little evidence for significant negative relations (trade-offs) between the three systems. This also applied to fish exposed to combinations of the stressors. This high phenotypic flexibility of trout in their resource allocation suggests that linear resource allocations as mechanisms of phenotypic plasticity may be too simplistic, but it also may point to a greater capacity of ectothermic than endothermic vertebrates to maintain key physiological processes under competing resource needs due to lower maintenance costs.

Effects of food availability on growth performance and immune-related gene expression of juvenile olive flounder (Paralichthys olivaceus)

Unfavorable environmental conditions and inappropriate culture practices have increased the vulnerability of cultured fish to disease infection. Up to date many studies have aimed to determine a feeding regimen to maximize productivity; however, very little information on immune responses of cultured fish in response to underfeeding or overfeeding is available. Therefore, a preliminary study was conducted to evaluate effects of graded feeding levels (i.e., food availability) on growth performance and immune-related gene expression of juvenile olive flounder (Paralichthys olivaceus). Six different feeding rates including 1, 4, 7, 10, 13, and 16% body weight per day (BW/d) were randomly assigned to three replicate tanks stocking 150 fish (average initial body weight: 0.27 ± 0.02 g; mean ± SD) per tank. A feeding trial lasted for two weeks. Based on the results of the weight gain, nutrient gain, and whole-body compositions and energy content, the feeding rate of 10%, 13%, and 16% BW/d resulted in high nutritional status, whereas the feeding rate of 1% and 4% BW/d resulted in low nutritional status. Intermediate nutritional status was observed at the feeding rate of 7% BW/d. In the given rearing conditions the optimum feeding rate resulting in the maximum growth was estimated to be 11.9% BW/d based on the quadratic broken-line regression model, chosen as the best-fit model among the tested models. Expression of immune-related genes including IL-8 and IgM was significantly down-regulated in the flounder fed at 1% BW/d in comparison to those fed at 7% BW/d. Interestingly, expression of these genes in the flounder fed at 10%, 13%, and 16% BW/d was relatively down-regulated in comparison to that of the flounder fed at 7% BW/d. Although no statistical difference was detected, overall response patterns of other immune-related genes, including TLR3, polymeric Ig receptor, lysozyme C-type, GPx, SOD, and Trx followed what IL-8 and IgM exhibited in response to the various feeding rates. Given the current challenges in aquaculture of the flounder our findings suggest to prohibit underfeeding or overfeeding (i.e., ad-libitum feeding) when culturing the young flounder.

Differential alternative splicing coupled to nonsense-mediated decay of mRNA ensures dietary restriction-induced longevity

Alternative splicing (AS) coupled to nonsense-mediated decay (AS-NMD) is a conserved mechanism for post-transcriptional gene regulation. Here we show that, during dietary restriction (DR), AS is enhanced in Caenorhabditis elegans and mice. A splicing mediator hrpu-1 regulates a significant part of these AS events in C. elegans; knocking it down suppresses DR-mediated longevity. Concurrently, due to increased AS, NMD pathway genes are upregulated and knocking down UPF1 homologue smg-2 suppresses DR lifespan. Knockdown of NMD during DR significantly increases the inclusion of PTC-containing introns and the lengths of the 3′UTRs. Finally, we demonstrate that PHA-4/FOXA transcriptionally regulates the AS-NMD genes. Our study suggests that DR uses AS to amplify the proteome, supporting physiological remodelling required for enhanced longevity. This increases the dependence on NMD, but also helps fine-tune the expression of metabolic and splicing mediators. AS-NMD may thus provide an energetically favourable level of dynamic gene expression control during dietary restriction.

Alternative splicing coupled to nonsense-mediated decay (AS-NMD) is a conserved mechanism for post-transcriptional gene regulation. Here, the authors provide evidence that AS-NMD is enhanced during dietary restriction (DR) and is required for DR-mediated longevity assurance in C. elegans.

Effect of temperature and food restriction on immune function in striped hamsters (Cricetulus barabensis)

Small mammals in temperate areas face seasonal fluctuations of temperature and food availability, both of which may influence their immune responses, which are critical to survival. In the present study, we tested the hypothesis that low temperature and food restriction suppress immune function in striped hamsters (Cricetulus barabensis). Thirty-seven adult male hamsters were randomly assigned to warm (23±1°C) and cold (5±1°C) treatment groups, which were further divided into fed and food-restricted groups. Body mass was not affected by cold stress, food restriction or the interaction cold stress×food restriction. Cold stress decreased total body fat mass, haematological parameters including white blood cells, lymphocytes and neutrophilic granulocytes, and immunoglobin (Ig) M titres 5 days after injecting keyhole limpet haemocyanin (KLH). However, cold temperature increased bacterial killing capacity, indicative of innate immunity, and did not affect the mass of the thymus and spleen, intermediate granulocytes, the phytohaemagglutinin (PHA) response and the levels of blood glucose and serum leptin. Corticosterone concentration was affected significantly by the interaction cold stress×food restriction but not by cold stress or food restriction alone. Food restriction reduced thymus mass, but other immunological parameters including body fat mass, spleen mass, haematological parameters, innate immunity, PHA response, the titres of IgM and IgG, and the levels of blood glucose and serum leptin were all not affected by food restriction or the interaction cold stress×food restriction. Innate immunity was positively correlated with leptin levels, whereas no significant correlations were observed in the levels of blood glucose, serum leptin, corticosterone and all the detected immune parameters. Our results show that cold stress suppressed humoral immunity but enhanced innate immunity and did not affect cellular immunity in striped hamsters. Most immunological indices were not influenced by food restriction. Blood glucose, leptin and corticosterone could not explain the changes of innate, cellular and humoral immunity upon cold stress or food restriction in striped hamsters.

Calorie Restriction Attenuates Terminal Differentiation of Immune Cells

Immune senescence is a natural consequence of aging and may contribute to frailty and loss of homeostasis in later life. Calorie restriction increases healthy life-span in C57BL/6J (but not DBA/2J) mice, but whether this is related to preservation of immune function, and how it interacts with aging, is unclear. We compared phenotypic and functional characteristics of natural killer (NK) cells and T cells, across the lifespan, of calorie-restricted (CR) and control C57BL/6 and DBA/2 mice. Calorie restriction preserves a naïve T cell phenotype and an immature NK cell phenotype as mice age. The splenic T cell populations of CR mice had higher proportions of CD11a^-CD44^lo cells, lower expression of TRAIL, KLRG1, and CXCR3, and higher expression of CD127, compared to control mice. Similarly, splenic NK cells from CR mice had higher proportions of less differentiated CD11b^-CD27⁺ cells and correspondingly lower proportions of highly differentiated CD11b⁺CD27^-NK cells. Within each of these subsets, cells from CR mice had higher expression of CD127, CD25, TRAIL, NKG2A/C/E, and CXCR3 and lower expression of KLRG1 and Ly49 receptors compared to controls. The effects of calorie restriction on lymphoid cell populations in lung, liver, and lymph nodes were identical to those seen in the spleen, indicating that this is a system-wide effect. The impact of calorie restriction on NK cell and T cell maturation is much more profound than the effect of aging and, indeed, calorie restriction attenuates these age-associated changes. Importantly, the effects of calorie restriction on lymphocyte maturation were more marked in C57BL/6 than in DBA/2J mice indicating that delayed lymphocyte maturation correlates with extended lifespan. These findings have implications for understanding the interaction between nutritional status, immunity, and healthy lifespan in aging populations.

The Role of Steroid Hormones in the Modulation of Neuroinflammation by Dietary Interventions

Steroid hormones, such as sex hormones and glucocorticoids, have been demonstrated to play a role in different cellular processes in the central nervous system, ranging from neurodevelopment to neurodegeneration. Environmental factors, such as calorie intake or fasting frequency, may also impact on such processes, indicating the importance of external factors in the development and preservation of a healthy brain. The hypothalamic-pituitary-adrenal axis and glucocorticoid activity play a role in neurodegenerative processes, including in disorders such as in Alzheimer's and Parkinson's diseases. Sex hormones have also been shown to modulate cognitive functioning. Inflammation is a common feature in neurodegenerative disorders, and sex hormones/glucocorticoids can act to regulate inflammatory processes. Intermittent fasting can protect the brain against cognitive decline that is induced by an inflammatory stimulus. On the other hand, obesity increases susceptibility to inflammation, while metabolic syndromes, such as diabetes, are associated with neurodegeneration. Consequently, given that gonadal and/or adrenal steroids may significantly impact the pathophysiology of neurodegeneration, via their effect on inflammatory processes, this review focuses on how environmental factors, such as calorie intake and intermittent fasting, acting through their modulation of steroid hormones, impact on inflammation that contributes to cognitive and neurodegenerative processes.

Protection against renal ischemia-reperfusion injury through hormesis? Dietary intervention versus cold exposure

AIM

Dietary restriction (DR) and fasting (FA) induce robust protection against the detrimental effects of renal ischemia-reperfusion injury (I/RI). Several mechanisms of protection have been proposed, such as hormesis. Hormesis is defined as a life-supporting beneficial effect resulting from the cellular responses to single or multiple rounds of (mild) stress. The cold exposure (CE) model is a stress model similar to DR, and has been shown to have hormetic effects and has proved to increase longevity. CE is considered to be the most robust method to increase metabolism through activation of brown adipocytes. BAT has been considered important in etiology of obesity and its metabolic consequences.

MATERIALS AND METHODS

Since DR, FA, and CE models are proposed to work through hormesis, we investigated physiology of adipose tissue and effect on BAT in these models and compared them to ad libitum (AL) fed mice. We also studied the differential effect of these stress models on immunological changes, and effect of CE on renal I/RI.

KEY FINDINGS

We show similar physiological changes in adiposity in male C57Bl/6 mice due to DR, FA and CE, but the CE mice were not protected against renal I/RI. The immunophenotypic changes observed in the CE mice were similar to the AL animals, in contrast to FA mice, that showed major immunophenotypic changes in the B and T cell development stages in primary and secondary lymphoid organs.

SIGNIFICANCE

Our findings thus demonstrate that DR, FA and CE are hormetic stress models. DR and FA protect against renal I/IR, whereas CE could not.

Low, rather than high, body mass index confers increased risk for post-liver transplant death and graft loss: Risk modulated by model for end-stage liver disease

With increasing attention being paid to optimizing patient outcomes, it has been proposed that liver transplantation (LT) for individuals with elevated body mass index (BMI) values and high Model for End-Stage Liver Disease (MELD) scores may adversely affect post-LT outcomes. We investigated the impact of BMI on post-LT outcomes in the context of MELD at LT. Using United Network for Organ Sharing data, we identified all adult (≥ 18 years) primary LT recipients from March 1, 2002 to September 30, 2011. BMI categories included the following: underweight, normal, overweight, class I obese, class II obese, and class III obese (<18.5; 18.5-24.9; 25-29.9; 30-34.9; 35-39.9; ≥ 40 kg/m(2), respectively). One-year post-LT death and graft loss were modeled using Cox regression, including interactions between BMI and MELD. A total of 45,551 adult recipients were identified: 68% male; median (interquartile range [IQR]) age 55 years (IQR, 49-60 years); MELD, 19 (IQR, 13-26); and donor risk index, 1.39 (IQR, 1.12-1.69). Representations in the BMI categories were underweight (n = 863, 2%), normal (n = 13,262, 29%), overweight (n = 16,329, 36%), class I obese (n = 9639, 21%), class II obese (n = 4062, 9%), and class III obese (n = 1396, 3%). In adjusted analyses, elevated BMI was not associated with increased risk for death or graft loss. Among the underweight, there were significant interactions between BMI and MELD with respect to death (P = 0.02) and graft loss (P = 0.01), with significantly increased risks for death (hazard ratio [HR], 1.70; 95% confidence interval [CI], 1.38-2.09; P = 0.006) and graft loss (HR, 1.45; 95% CI, 1.21-1.74; P = 0.02) among those with low MELD (≤ 26), compared to normal BMI recipients with low MELD. In conclusion, overweight and obese LT recipients do not have increased risk of death or graft loss regardless of MELD. Underweight patients are at increased risk for poor outcomes post-LT, specifically underweight recipients with low MELD have increased risk for death and graft loss. Mechanisms underlying this phenomenon warrant further investigation.

Postnatal nutritional restriction affects growth and immune function of piglets with intra-uterine growth restriction

Postnatal rapid growth by excess intake of nutrients has been associated with an increased susceptibility to diseases in neonates with intra-uterine growth restricted (IUGR). The aim of the present study was to determine whether postnatal nutritional restriction could improve intestinal development and immune function of neonates with IUGR using piglets as model. A total of twelve pairs of normal-birth weight (NBW) and IUGR piglets (7 d old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake (RNI) by artificially liquid feeding for a period of 21 d. Blood samples and intestinal tissues were collected at necropsy and were analysed for morphology, digestive enzyme activities, immune cells and expression of innate immunity-related genes. The results indicated that both IUGR and postnatal nutritional restriction delayed the growth rate during the sucking period. Irrespective of nutrient intake, piglets with IUGR had a significantly lower villous height and crypt depth in the ileum than the NBW piglets. Moreover, IUGR decreased alkaline phosphatase activity while enhanced lactase activity in the jejunum and mRNA expressions of Toll-like receptor 9 (TLR-9) and DNA methyltransferase 1 (DNMT1) in the ileum of piglets. Irrespective of body weight, RNI significantly decreased the number and/or percentage of peripheral leucocytes, lymphocytes and monocytes of piglets, whereas the percentage of neutrophils and the ratio of CD4+ to CD8+ were increased. Furthermore, RNI markedly enhanced the mRNA expression of TLR-9 and DNMT1, but decreased the expression of NOD2 and TRAF-6 in the ileum of piglets. In summary, postnatal nutritional restriction led to abnormal cellular and innate immune response, as well as delayed the growth and intestinal development of IUGR piglets.

The effect of Ramadan fasting on quiescent systemic lupus erythematosus (SLE) patients' disease activity, health quality of life and lipid profile: a pilot study

SLE is a common autoimmune disease with considerable morbidity. Ramadan fasting is a religious custom Muslims regularly practice. We aimed to evaluate the effect of Ramadan fasting on SLE patients' disease activity, health quality of life and lipid profile. We conducted this case control study as a pilot study in 40 quiescent SLE patients, 21 cases who decided to fast and 19 controls who decided not to have Ramadan fasting between August and November 2009 in lupus unit of Rheumatology Research Center in Tehran University of Medical Sciences, Iran. They were assessed for SLE Disease Activity Index, lipid profile and quality of life with Short-Form 36 (SF-36) Health Survey, 1 day before Ramadan, the day after and 3 months after Ramadan fasting. After 24.1 ± 5.4 (mean ± SD) days of fasting, anti-ds DNA increased for 0.34 ± 0.41 mmol/dL in cases versus 0.07 ± 0.31 in controls (P = 0.026). Likewise C3 increased more dramatically in cases (16.8 ± 17.5 vs. 2.3 ± 13.2 mg/dL, P = 0.006). Three months after fasting, anti-ds DNA was still increased 0.28 ± 0.46 mmol/dL in cases while a 0.02 ± 0.43 mmol/dL drop in controls was detected (P = 0.04). On the contrary, C3 returned to baseline. These changes were not accompanied with significant changes in disease activity and health quality of life. Ramadan fasting had no effect on lipid profile except for delayed total cholesterol decrease in cases in comparison with controls (16.4 ± 29.4 decrease vs. 4.6 ± 23.9 mg/dL decrease, P = 0.018). Ramadan fasting probably has no detrimental effect on SLE patients' disease activity and their quality of life in the quiescent phase of disease.

Diet, microbiota and autoimmune diseases

There is growing evidence that the commensal bacteria in the gastrointestinal tract (the gut microbiota) influence the development of autoimmunity in rodent models. Since humans have co-evolved with commensals for millennia, it is likely that people, who are genetically predisposed to autoimmunity, harbor gut microbial communities that similarly influence the onset and/or severity of disease. Beyond the current efforts to identify such disease-promoting or -preventing commensals ("pathobionts" or "symbionts"), it will be important to determine what factors modulate them. Dietary changes are known to affect both the composition and function of the gut microbial communities, which in turn can alter the innate and adaptive immune system. In this review, we focus on the relationships between diet, microbiota, and autoimmune diseases. We hypothesize that the beneficial and life-prolonging effects of caloric restriction on a variety of autoimmune models including lupus might partly be mediated by its effects on the gut microbiome and associated virome, the collection of all viruses in the gut. We give recent examples of the immunomodulatory potential of select gut commensals and their products or diet-derived metabolites in murine models of arthritis, multiple sclerosis, and type 1 diabetes. Lastly, we summarize the published phenotypes of germ-free mouse models of lupus and speculate on any role of the diet-sensitive microbiome and virome in systemic lupus and the related antiphospholipid syndrome.

Fasting mitigates immediate hypersensitivity: a pivotal role of endogenous D-beta-hydroxybutyrate

Background

Fasting is a rigorous type of dietary restriction that is associate with a number of health benefits. During fasting, ketone bodies significantly increase in blood and become major body fuels, thereby sparing glucose. In the present study, we investigated effects of fasting on hypersensitivity. In addition, we also investigated the possible role of D-beta-hydroxybutyrate provoked by fasting in the attenuation of immediate hypersensitivity by fasting.

Methods

Effects of fasting on systemic anaphylaxis were examined using rat model of toluene 2, 4-diisocyanate induced nasal allergy. In addition to food restriction, a ketogenic high-fat and low-carbohydrate diet that accelerates fatty acid oxidation and systemic instillation of D-beta-hydroxybutyrate were employed to elevate internal D-beta-hydroxybutyrate concentration. We assessed relationship between degranulation of rat peritoneal mast cells and internal D-beta-hydroxybutyrate concentration in each treatment. Changes in [Ca²⁺]i responses to compound 48/80 were analyzed in fura 2-loaded rat peritoneal mast cells derived from the ketogenic diet and fasting.

Results

Immediate hypersensitivity reaction was significantly suppressed by fasting. A significant reduction in mast cells degranulation, induced by mast cell activator compound 48/80, was observed in rat peritoneal mast cells delivered from the 24 hours fasting treatment. In addition, mast cells delivered from a ketogenic diet and D-beta-hydroxybutyrate infusion treatment also had reduced mast cell degranulation and systemic D-beta-hydroxybutyrate concentrations were elevated to similar extent as the fasting state. The peak increase in [Ca²⁺]i was significantly lower in the ketogenic diet and fasting group than that in the control diet group.

Conclusions

The results of the present study demonstrates that fasting suppress hypersensitivity reaction, and indicate that increased level of D-beta-hydroxybutyrate by fasting plays an important role, via the stabilization of mast cells, in suppression of hypersensitivity reaction.

A systematic approach to the preoperative medical evaluation of adults

The number, age, and medical complexity of patients undergoing elective noncardiac surgery is rising worldwide. Internists, family physicians, and midlevel providers asked to perform preoperative medical evaluations. However, lack of consensus has led to wide variation in practice in what is included and addressed in these evaluations, and the efficacy of these assessments has been debated. The intended purpose of the evaluation seems to be universally accepted as aiming to assess and identify risks associated with the patient's comorbid medical conditions and the specific surgical procedure. The goal is to minimize those risks. Herein, we propose a systematic approach to the preoperative medical evaluation based on the best available evidence and expert opinion, with an emphasis on identifying all potentially pertinent patient- and surgery-specific risk factors.

Considerations for protein supplementation in warfighters

Ingestion of dietary protein stimulates the synthesis of numerous body proteins. This effect is manifest via hyperaminoacidemia with insulin as a permissive factor. In a sedentary person in energy balance, it is possible to maintain nitrogen balance while consuming protein at an intake of 0.8 g protein · kg(-1) · d(-1). What is unclear is whether being in nitrogen balance is optimal for protein synthesis and not merely adequate and representative of adaptive strategies that could lead to accommodation in "stressed" physiological states. It is clear that being in negative energy balance results in reductions in lean mass and reduced rates of protein synthesis, which can be mitigated by consumption of higher (i.e., 2-3 times the RDA) dietary protein. That long-term practice of inadequate protein intake leads to reduced metabolic, physiological, and physical function provides the basic rationale for the consumption of more than merely adequate protein to prevent not only adaptation but accommodation. Warfighters engaged in combat have been shown to have high daily physical activity energy expenditure, engage in voluntary energy restriction, and are under high metabolic and mental stress. Thus, as a group warfighters would be at risk of consuming suboptimal protein intakes and therefore may benefit from higher amounts of dietary protein intake. Balanced against the potential risk of consuming higher protein, the scientific documentation for which is lacking, there is a strong rationale for the recommendation of higher protein intakes in warfighters who are engaged in field operations.

Impact of Korean pine nut oil on weight gain and immune responses in high-fat diet-induced obese mice

Korean pine nut oil (PNO) has been reported to have favorable effects on lipid metabolism and appetite control. We investigated whether PNO consumption could influence weight gain, and whether the PNO-induced effect would result in an improvement of immune function in high-fat diet (HFD)-induced obese mice. C57BL/6 mice were fed control diets with 10% energy fat from either PNO or soybean oil (SBO), or HFDs with 45% energy fat from 10% PNO or SBO and 35% lard, 20% PNO or SBO and 25% lard, or 30% PNO or SBO and 15% lard for 12 weeks. The proliferative responses of splenocytes upon stimulation with concanavalin A (Con A) or lipopolysaccharide (LPS), Con A-stimulated production of interleukin (IL)-2 and interferon (IFN)-γ, and LPS-stimulated production of IL-6, IL-1β, and prostaglandin E₂ (PGE₂) by splenocytes were determined. Consumption of HFDs containing PNO resulted in significantly less weight gain (17% less, P < 0.001), and lower weight gain was mainly due to less white adipose tissue (18% less, P = 0.001). The reduction in weight gain did not result in the overall enhancement in splenocyte proliferation. Overall, PNO consumption resulted in a higher production of IL-1β (P = 0.04). Replacement of SBO with PNO had no effect on the production of IL-2, IFN-γ, IL-6, or PGE₂ in mice fed with either the control diets or HFDs. In conclusion, consumption of PNO reduced weight gain in mice fed with HFD, but this effect did not result in the overall improvement in immune responses.

The role of the T cell in age-related inflammation

Ageing is accompanied by alterations to T-cell immunity and also by a low-grade chronic inflammatory state termed inflammaging. The significance of these phenomena is highlighted by their being predictors of earlier mortality. We have recently published that the proinflammatory cytokine TNFα is a strong inducer of CD4(+) T-cell senescence and T-cell differentiation, adding to the growing body of literature implicating proinflammatory molecules in mediating these critical age-related T-cell alterations. Moreover, the inflammatory process is also being increasingly implicated in the pathogenesis of many common and severe age-related diseases, including cancer, cardiovascular diseases and type 2 diabetes. Furthermore, major age-related risk factors for poor health, such as obesity, stress and smoking, are also associated with an upregulation in systemic inflammatory markers. We propose the idea that the ensuing inflammatory response to influenza infection propagates cardiovascular diseases and constitutes a major cause of influenza-related mortality. While inflammation is not a negative phenomenon per se, this age-related dysregulation of inflammatory responses may play crucial roles driving age-related pathologies, T-cell immunosenescence and CMV reactivation, thereby underpinning key features of the ageing process.

Sirtuin-1 is a nutrient-dependent modulator of inflammation

Inflammation accompanies obesity and its comorbidities—type 2 diabetes, non-alcoholic fatty liver disease and atherosclerosis, among others—and may contribute to their pathogenesis. Yet the cellular machinery that links nutrient sensing to inflammation remains incompletely characterized. The protein deacetylase sirtuin-1 (SirT1) is activated by energy depletion and plays a critical role in the mammalian response to fasting. More recently it has been implicated in the repression of inflammation. SirT1 mRNA and protein expression are suppressed in obese rodent and human white adipose tissue, while experimental reduction of SirT1 in adipocytes and macrophages causes low-grade inflammation that mimics that observed in obesity. Thus suppression of SirT1 during overnutrition may be critical to the development of obesity-associated inflammation. This effect is attributable to multiple actions of SirT1, including direct deacetylation of NFκB and chromatin remodeling at inflammatory gene promoters. In this work, we report that SirT1 is also suppressed by diet-induced obesity in macrophages, which are key contributors to the ontogeny of metabolic inflammation. Thus, SirT1 may be a common mechanism by which cells sense nutrient status and modulate inflammatory signaling networks in accordance with organismal energy availability.

NK cell maturation and function in C57BL/6 mice are altered by caloric restriction

NK cells are a heterogenous population of innate lymphocytes with diverse functional attributes critical for early protection from viral infections. We have previously reported a decrease in influenza-induced NK cell cytotoxicity in 6-mo-old C57BL/6 calorically restricted (CR) mice. In the current study, we extend our findings on the influence of CR on NK cell phenotype and function in the absence of infection. We demonstrate that reduced mature NK cell subsets result in increased frequencies of CD127(+) NK cells in CR mice, skewing the function of the total NK cell pool. NK cells from CR mice produced TNF-α and GM-CSF at a higher level, whereas IFN-γ production was impaired following IL-2 plus IL-12 or anti-NK1.1 stimulation. NK cells from CR mice were highly responsive to stimulation with YAC-1 cells such that CD27(-)CD11b(+) NK cells from CR mice produced granzyme B and degranulated at a higher frequency than CD27(-)CD11b(+) NK cells from ad libitum fed mice. CR has been shown to be a potent dietary intervention, yet the mechanisms by which the CR increases life span have yet to be fully understood. To our knowledge, these findings are the first in-depth analysis of the effects of caloric intake on NK cell phenotype and function and provide important implications regarding potential ways in which CR alters NK cell function prior to infection or cancer.

Growth factors, nutrient signaling, and cardiovascular aging

Growth factors regulated by specific macronutrients have been shown to promote aging and accelerate mortality in the majority of the organisms studied. In particular, the enzymes activated by growth hormone, insulin, and insulin-like growth factor-1 in mammals and their orthologs in simple model organisms represent perhaps the best-understood proteins involved in the aging process. Dietary restriction, which reduces the level of insulin-like growth factor-1 and of other growth factors, has been associated with protection from diabetes, cancer, and cardiovascular diseases, and deficiencies in growth hormone signaling and insulin-like growth factor-1 are strongly associated with protection from cancer and diabetes in both mice and humans; however, their role in cardiac function and cardiovascular diseases is controversial. Here, we review the link between growth factors, cardiac function, and heart disease with focus on the cardioprotective and sensitizing effect of growth factors in both model organisms and humans.

Caloric restriction and chronic inflammatory diseases

A reduction in calorie intake [caloric restriction (CR)] appears to consistently decrease the biological rate of aging in a variety of organisms as well as protect against age-associated diseases including chronic inflammatory disorders such as cardiovascular disease and diabetes. Although the mechanisms behind this observation are not fully understood, identification of the main metabolic pathways affected by CR has generated interest in finding molecular targets that could be modulated by CR mimetics. This review describes the general concepts of CR and CR mimetics as well as discusses evidence related to their effects on inflammation and chronic inflammatory disorders. Additionally, emerging evidence related to the effects of CR on periodontal disease in non-human primates is presented. While the implementation of this type of dietary intervention appears to be challenging in our modern society where obesity is a major public health problem, CR mimetics could offer a promising alternative to control and perhaps prevent several chronic inflammatory disorders including periodontal disease.

Caloric restriction modifies both innate and adaptive immunity in the mouse small intestine

Although caloric restriction (CR) apparently has beneficial effects on the immune system, its effects on the immunological function of the intestinal mucosa are little known. The present study explored the effect of CR on the innate and adaptive intestinal immunity of mice. Balb/c mice were either fed ad libitum (control) or on alternate days fed ad libitum and fasted (caloric restriction). After 4 months, an evaluation was made of IgA levels in the ileum, the gene expression for IgA and its receptor (pIgR), as well as the expression of two antimicrobial enzymes (lysozyme and phospholipase A2) and several cytokines of the intestinal mucosa. CR increased the gene expression of lysozyme and phospholipase A2. The levels of IgA were diminished in the ileum, which apparently was a consequence of the reduced transport of IgA by pIgR. In ileum, CR increased the gene expression for most cytokines, both pro- and anti-inflammatory. Hence, CR differentially modified the expression of innate and adaptive immunity mediators in the intestine.

Caloric restriction increases free radicals and inducible nitric oxide synthase expression in mice infected with Salmonella Typhimurium

It is well known that CR (caloric restriction) reduces oxidative damage to proteins, lipids and DNA, although the underlying mechanism is unclear. However, information concerning the effect of CR on the host response to infection is sparse. In this study, 6-month-old mice that were fed AL (ad libitum) or with a CR diet were infected with Salmonella serovar Typhimurium. EPR (electron paramagnetic resonance; also known as ESR (electron spin resonance)) was used to identify FRs (free radicals). These results were subsequently correlated with SOD (superoxide dismutase) catalytic activity, iNOS [inducible NOS (nitric oxide synthase) or NOSII] expression and NO (nitric oxide) content. EPR analysis of liver samples demonstrated that there was a higher quantity of FRs and iron-nitrosyl complex in infected mice provided with a CR diet as compared with those on an AL diet, indicating that CR was beneficial by increasing the host response to Salmonella Typhimurium. Furthermore, in infected mice on the CR diet, NOSII expression was higher, NO content was greater and spleen colonization was lower, compared with mice on the AL diet. No changes in SOD activity were detected, indicating that the NO produced participated more in the formation of iron-nitrosyl complexes than peroxynitrite. These results suggest that CR exerts a protective effect against Salmonella Typhimurium infection by increasing NO production.

Nonhuman primate models of human immunology

Nonhuman primates have been used for biomedical research for several decades. The high level of genetic homology to humans coupled with their outbred nature has made nonhuman primates invaluable preclinical models. In this review, we summarize recent advances in our understanding of the nonhuman primate immune system, with special emphasis on studies carried out in rhesus macaque (Macaca mulatta). We highlight the utility of nonhuman primates in the characterization of immune senescence and the evaluation of new interventions to slow down the aging of the immune system.

Caloric restriction and longevity: effects of reduced body temperature

Caloric restriction (CR) causes a reduction in body temperature (T(b)) which is suggested to contribute to changes that increase lifespan. Moreover, low T(b) has been shown to improve health and longevity independent of CR. In this review we examine the connections between CR, T(b) and mechanisms that influence longevity and ageing. Recent findings regarding the overlapping mechanisms of CR and T(b) that benefit longevity are discussed, including changes in body composition, hormone regulation, and gene expression, as well as reductions in low-level inflammation and reactive oxygen species-induced molecular damage. This information is summarized in a model describing how CR and low T(b), both synergistically and independently, increase lifespan. Moreover, the nascent notion that the rate of ageing may be pre-programmed in response to environmental influences at critical periods of early development is also considered. Based on current evidence, it is concluded that low T(b) plays an integral role in mediating the effects of CR on health and longevity, and that low T(b) may exert independent biological changes that increase lifespan. Our understanding of the overlap between CR- and T(b)-mediated longevity remains incomplete and should be explored in future research.

Caloric restriction reduces IgA levels and modifies cytokine mRNA expression in mouse small intestine

The aim of this study was to determine the effect of caloric restriction (CR) in mouse small intestine on the production and secretion of immunoglobulin (Ig) A, the population of lymphocytes in the lamina propria, and the expression of cytokines that mediate and regulate innate and adaptive immunity. One group of young Balb/c mice was fed ad libitum, while the CR group was fed ad libitum and fasted on alternate days. When mice were six months old, IgA levels in the proximal small intestine were quantified by enzyme-linked immunosorbent assay, while the number of IgA containing cells, CD4(+) T cells and CD8(+) T cells in the duodenal mucosa was determined by immunohistochemistry. Furthermore, the expression of several intestinal cytokines, the genes for α-chain IgA, and the polymeric Ig receptor (pIgR) were analyzed by real-time polymerase chain reaction. CR decreased the levels of IgA in the intestine, apparently a consequence of a reduced number of IgA(+) cells in the lamina propria that decrease the production and secretion of this Ig, and a reduced secretion of S-IgA into the bile, which in turn discharges into the proximal intestine. Contrarily, CR increased the expression of genes for α-chain IgA, and the pIgR, indicating that transport of IgA was not a key factor in the decrease of this Ig. Additionally, CR modified the expression of genes for tumor necrosis factor-α, interferon-γ, tumor growth factor-β, interleukin (IL)-2 and IL-10, all of which regulate the synthesis of IgA and pIgR, the inflammatory response, and the immune response in the intestine.

Anti-inflammatory effects of serum isolated from animals on intermittent feeding in C6 glioma cell line

Multiple sclerosis (MS) is a demyelinating disease of the CNS. Early inflammation leads to later destruction of myelin in MS. Dietary restriction (DR) produces anti-inflammatory and immunomodulatory effects in many species. Based on the reported anti-inflammatory effects of DR, we investigated whether sera collected from rats fed on intermittent feeding (IF, a type of DR) diet could modulate cytokine secretion and matrix metalloproteinase (MMP-2) activity that are involved in MS pathogenesis. Cytokine levels (IL-6 and TGF-β1) were measured in supernatant from C6 glioma cell line cultures treated with IF and AL fed animals' sera by enzyme-linked immunosorbent assay (ELISA) and MMP-2 activity was detected by gelatin zymography. Our results indicated that sera of animals on IF diet significantly reduced IL-6 (p<0.05) and increased TGF-β1 (p<0.05) production by C6 glioma cells. A significant decrease (p<0.05) in MMP-2 activity was also found. These results indicate anti-inflammatory and immunomodulatory activity in the sera of animals on IF regimen on cells involved in multiple sclerosis pathogenesis. Further studies on the detection of factors responsible for such activities and their mechanism of action in MS pathogenesis are recommended.

Starvation alters the liver transcriptome of the innate immune response in Atlantic salmon (Salmo salar)

BACKGROUND

The immune response is an energy demanding process, which has effects in many physiological pathways in the body including protein and lipid metabolism. During an inflammatory response the liver is required to produce high levels of acute phase response proteins that attempt to neutralise an invading pathogen. Although this has been extensively studied in both mammals and fish, little is known about how high and low energy reserves modulate the response to an infection in fish which are ectothermic vertebrates. Food withdrawal in fish causes a decrease in metabolic rate so as to preserve protein and lipid energy reserves, which occurs naturally during the life cycle of many salmonids. Here we investigated how the feeding or fasting of Atlantic salmon affected the transcriptional response in the liver to an acute bacterial infection.

RESULTS

Total liver RNA was extracted from four different groups of salmon. Two groups were fed or starved for 28 days. One of each of the fed or starved groups was then exposed to an acute bacterial infection. Twenty four hours later (day 29) the livers were isolated from all fish for RNA extraction. The transcriptional changes were examined by micro array analysis using a 17 K Atlantic salmon cDNA microarray. The expression profiling results showed major changes in gene transcription in each of the groups. Enrichment for particular biological pathways was examined by analysis of gene ontology. Those fish that were starved decreased immune gene transcription and reduced production of plasma protein genes, and upon infection there was a further decrease in genes encoding plasma proteins but a large increase in acute phase response proteins. The latter was greater in magnitude than in the fish that had been fed prior to infection. The expression of several genes that were found altered during microarray analysis was confirmed by real time PCR.

CONCLUSIONS

We demonstrate that both starvation and infection have profound effects on transcription in the liver of salmon. There was a significant effect on the transcriptional response to infection depending on the prior feeding regime of the fish. It is likely that the energy demands on protein synthesis for acute phase response proteins are relatively high in the starved fish which have reduced energy reserves. This has implications for dietary control of fish if an immune response is anticipated.