Caloric restriction inhibits up-regulation of inflammatory cytokines and TNF-α, and activates IL-10 and haptoglobin in the plasma of streptozotocin-induced diabetic rats

Caloric restriction for the immunometabolic control of human health

Nutrition affects all physiological processes occurring in our body, including those related to the function of the immune system; indeed, metabolism has been closely associated with the differentiation and activity of both innate and adaptive immune cells. While excessive energy intake and adiposity have been demonstrated to cause systemic inflammation, several clinical and experimental evidence show that calorie restriction (CR), not leading to malnutrition, is able to delay aging and exert potent anti-inflammatory effects in different pathological conditions. This review provides an overview of the ability of different CR-related nutritional strategies to control autoimmune, cardiovascular, and infectious diseases, as tested by preclinical studies and human clinical trials, with a specific focus on the immunological aspects of these interventions. In particular, we recapitulate the state of the art on the cellular and molecular mechanisms pertaining to immune cell metabolic rewiring, regulatory T cell expansion, and gut microbiota composition, which possibly underline the beneficial effects of CR. Although studies are still needed to fully evaluate the feasibility and efficacy of the nutritional intervention in clinical practice, the experimental observations discussed here suggest a relevant role of CR in lowering the inflammatory state in a plethora of different pathologies, thus representing a promising therapeutic strategy for the control of human health.

The Effect of Moderate-Intensity Physical Exercise on Some Serum Inflammation Markers and the Immune System in Rats Fed Intermittent Fasting with a High-Fat Diet

Background and Objectives: This study aimed to investigate the impact of moderate-intensity physical exercise on serum inflammation markers and the immune system in rats that were fed a high-fat diet (HFD) with intermittent fasting. Materials and Methods: A total of 48 Wistar albino male rats were included in the study and divided into eight groups, each consisting of six rats. Group 1 served as the control group (CG), receiving a standard diet. Group 2 followed the standard nutrition program with intermittent fasting (CG + IF). Group 3 underwent exercise with a standard diet (CG + E). Group 4 underwent both a standard diet with intermittent fasting and exercise (CG + IF + E). Group 5 was fed a high-fat diet (HFD). Group 6 received a high-fat diet with intermittent fasting (HFD + IF). Group 7 followed a high-fat diet with exercise (HFD + E). Group 8 underwent both a high-fat diet with intermittent fasting and exercise (HFD + IF + E). The study lasted for 8 weeks. Results: The results of the analysis show that lymphocyte cell levels in groups HFD + IF, HFD + IF, and HFD + IF + E were higher compared to groups CG-HFD (p < 0.05). Additionally, B lymphocyte and monocyte cell levels were higher in group HFD + IF + E compared to groups CG, CG + IF, and CG + IF + E, as well as CG, CG + IF, and CG + E, respectively. TNF-α levels were significantly higher in group HFD compared to the other groups. Furthermore, IL 10 levels were higher in group HFD + IF + E compared to the other groups. Conclusions: These findings indicate that moderate exercise and intermittent fasting, particularly in groups fed a high-fat diet, increased anti-inflammatory cytokine levels, and certain immune system cell counts, while decreasing pro-inflammatory cytokine levels.

Effect of Ramadan fasting on salivary IgA, serum IgA, IL-17, and IL-22 levels

Background: nutritional factors might affect the number and function of immune cells for instance the production of cytokines and immunoglobulins. Ramadan fasting is intermittent abstinence from eating and drinking for almost four weeks. Aim: The present study aimed to investigate the influence of intermittent fasting on serum IgA, salivary IgA (sIgA), interleukin (IL)-17, and IL-22 levels. Methods: 40 healthy men aged 19-29 years were evaluated before and during the fourth week of Ramadan fasting for IgA levels by the nephelometric method as well as salivary IgA (sIgA), IL-17, and IL-22 amounts using enzyme-linked immunosorbent assay (ELISA). Results: serum IgA levels reduced significantly at the end of Ramadan fasting (225.8 ± 87 vs. 196 ± 70 mg/dl) (p-value<0.001); however, sIgA amounts did not differ between before and the last week of Ramadan. Serum IL-17 reduced significantly (2.93 ± 1.51 vs. 2.17 ± 1.33 pg/ml) (p-value = 0.006) whereas IL-22 levels remained approximately unchanged. Summary: four weeks of intermittent fasting during Ramadan reduced the serum levels of IgA and IL-17 but did not affect the production of sIgA and IL-22. These findings indicate a limited impact of intermittent fasting on mucosal immunity.

Caloric Restriction Alleviates CFA-Induced Inflammatory Pain via Elevating β-Hydroxybutyric Acid Expression and Restoring Autophagic Flux in the Spinal Cord

Inflammatory pain is the most common type of pain encountered in clinical practice; however, the currently available treatments are limited by insufficient efficacy and side effects. Therefore, new methods to relieve inflammatory pain targeting new mechanisms are urgently needed. Preclinical investigations have shown that CR (calorie restriction) exerts analgesic effects in neuropathic and cancer pain; however, the effect of CR on chronic inflammatory pain remains unknown. During calorie restriction, autophagy, a lysosome-dependent degradation process, can be activated to support cell survival. In the present study, we investigated the analgesic effects of CR on complete Freund’s adjuvant (CFA)-induced inflammatory pain. The accumulation of LC3-II and p62 showed impaired autophagic flux in the ipsilateral spinal cord of mice with CFA-induced inflammatory pain. CR alleviated mechanical allodynia and thermal hyperalgesia and reduced paw edema and pro-inflammatory factors following CFA administration. CR exerted an analgesic effect by restoring autophagic flux in the spinal cord. Regarding the mechanisms underlying the analgesic effects of CR, β-hydroxybutyric acid (BHB) was studied. CR increased BHB levels in the ipsilateral spinal cord. Furthermore, exogenous BHB administration exerted an analgesic effect by restoring autophagic flux in the spinal cords of CFA-induced inflammatory pain mice. Taken together, these results illustrated that CR relieved inflammatory pain by restoring autophagic flux in the spinal cord, while BHB controlled the benefits of CR, suggesting that CR or BHB might be a promising treatment for inflammatory pain.

Glycemic control by umbilical cord-derived mesenchymal stem cells promotes effects of fasting-mimicking diet on type 2 diabetic mice

BACKGROUND

Hepatic steatosis is a big hurdle to treat type 2 diabetes (T2D). Fasting-mimicking diet (FMD) has been shown to be an effective intervention in dyslipidemia of T2D. However, fasting may impair the normal glucose metabolism. Human umbilical cord-derived mesenchymal stem cell (UC-MSC) transplantation has been discovered to regulate immune reactions and reduce hyperglycemia in diabetes. However, the effect of UC-MSCs on improving the lipid metabolism disorder is not quite satisfactory. We have investigated the efficacy comparison and interaction between FMD and UC-MSC infusion, aiming to establish effective T2D therapies and explore its mechanism.

METHODS

C57/BL6 mice were fed with high-fat diet (HFD) to induce a diet-induced obese (DIO) mouse model. Leptin receptor-deficient (db/db) mice were used for follow-up experiments. DIO or db/db mice were divided into 4 groups: phosphate buffer saline (PBS), UC-MSCs, FMD, and UC-MSCs + FMD. At the end of the study period, mice were fasted and sacrificed, with the measurement of physiological and biochemical indexes. In addition, the fresh liver, skin, and white adipose tissue were analyzed by histology.

RESULTS

FMD restored the lipid metabolism in DIO mice, whereas its capacity to rescue hyperglycemia was uncertain. Infusion of UC-MSCs was effective in T2D glycemic control but the impact on dyslipidemia was insufficient. Furthermore, both the glucose and the lipid alterations of DIO and db/db mice recovered after UC-MSCs combined with FMD. It was proved that UC-MSCs promoted FMD effects on ameliorating hyperglycemia and restoring the lipid metabolism in T2D mice, while FMD had little promotion effect on UC-MSCs. Mechanistically, we discovered that UC-MSC infusion significantly modulated systematic inflammatory microenvironment, which contributed to concerted actions with FMD.

CONCLUSIONS

We established a strategy that combined UC-MSC infusion and FMD and was effective in treating T2D, which provided potential approaches for developing novel clinical T2D therapies.

Role of dietary modifications in the management of type 2 diabetic complications

Diabetes is a chronic metabolic disorder with a high rate of morbidity and mortality. Insufficient insulin secretion and insulin action are two major causes for the development of diabetes, which is characterized by a persistent increase in blood glucose level. Diet and sedentary life style play pivotal role in development of vascular complications in type 2 diabetes. Dietary modification is associated with a reprogramming of nutrient intake, which are proven to be effective for the management of diabetes and associated complications. Dietary modifications modulate various molecular key players linked with the functions of nutrient signalling, regulation of autophagy, and energy metabolism. It activates silent mating type information regulation 2 homolog1 (SIRT1) and AMP-activated protein kinase (AMPK). AMPK mainly acts as an energy sensor and inhibits autophagy repressor Mammalian target of rapamycin (mTOR) under nutritional deprivation. Under calorie restriction (CR), SIRT1 gets activated directly or indirectly and plays a central role in autophagy via the regulation of protein acetylation. Dietary modification is also effective in controlling inflammation and apoptosis by decreasing the level of pro-inflammatory cytokines like nuclear factor kappa- beta (NF-kβ), tissue growth factor-beta (TGF-β), tissue necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). It also improves glucose homeostasis and insulin secretion through beta cell regeneration. This indicates calorie intake plays a crucial role in the pathogenesis of type 2 diabetes-associated complications. The present review, emphasizes the role of dietary modifications in diabetes and associated complications.

Seven-day fasting as a multimodal complex intervention for adults with type 1 diabetes: Feasibility, benefit and safety in a controlled pilot study

OBJECTIVES

Intermittent as well as prolonged fasting are receiving considerable attention and appear favorable in conditions such as metabolic syndrome, type 2 diabetes, and rheumatic diseases. Fasting for individuals with type 1 diabetes (T1D) is generally considered too risky. However, the ability and possibility to change from carbohydrate- to ketone-based fuel supply might be relevant for individuals with T1D. The aim of this patient-led research was to investigate the feasibility, benefit, and safety of a 7-d multimodal fasting intervention in individuals with T1D.

METHODS

This was a non-randomized controlled pilot study, with 20 participants with T1D and 10 without the disease. Data acquisition took place before, after, and 4 mo after the intervention and daily during intervention.

RESULTS

Of the individuals with T1D, 19 finished fasting. A mean β-hydroxybutyrate as representative ketone body increased to 2.8 ± 1.9 mmol/L on day 7; whereas average glucose remained between 4.9 (±1.5) and 7.5 (±2.3) mmol/L (89 ± 27 and 136 ± 40 mg/dL). Mean daily insulin dose was adjusted from 24.4 (3-50) IU on the day before fasting to 7.6 (0-26.7) IU on day 7. Quality of life (WHO-5) normalized from 54 (±4.4) to 68.8 (±15; P = 0.01) after fasting. There was a decrease from before until the follow-up 4 mo later of weight from 77.6 (±20.4) to 76.6 (±20.9) kg (P = 0.023) and for body mass index from 27.68 (±7.04) to 26.74 (±7.15) kg/m² (P = 0.008). Diastolic blood pressure increased from 69.75 (±11.41) to 75.74 (±8.42) mm Hg (P = 0.028) and stayed in a healthy range on average. Fasting-related side effects were all temporary, and slightly more prevalent in those with type 1 diabetes compared with the reference group.

CONCLUSIONS

This study demonstrated the feasibility, benefits, and safety aspects of a 7-d fast in adults with T1D.

Energy Restriction and Colorectal Cancer: A Call for Additional Research

: Colorectal cancer has the second highest cancer-related mortality rate, with an estimated 881,000 deaths worldwide in 2018. The urgent need to reduce the incidence and mortality rate requires innovative strategies to improve prevention, early diagnosis, prognostic biomarkers, and treatment effectiveness. Caloric restriction (CR) is known as the most robust nutritional intervention that extends lifespan and delays the progression of age-related diseases, with remarkable results for cancer protection. Other forms of energy restriction, such as periodic fasting, intermittent fasting, or fasting-mimicking diets, with or without reduction of total calorie intake, recapitulate the effects of chronic CR and confer a wide range of beneficial effects towards health and survival, including anti-cancer properties. In this review, the known molecular, cellular, and organismal effects of energy restriction in oncology will be discussed. Energy-restriction-based strategies implemented in colorectal models and clinical trials will be also revised. While energy restriction constitutes a promising intervention for the prevention and treatment of several malignant neoplasms, further investigations are essential to dissect the interplay between fundamental aspects of energy intake, such as feeding patterns, fasting length, or diet composition, with all of them influencing health and disease or cancer effects. Currently, effectiveness, safety, and practicability of different forms of fasting to fight cancer, particularly colorectal cancer, should still be contemplated with caution.

Dietary Energy Restriction Ameliorates Cognitive Impairment in a Mouse Model of Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the most common causes of neurological damage in young people. It was previously reported that dietary restriction, by either intermittent fasting (IF) or daily caloric restriction (CR), could protect neurons against dysfunction and degeneration in animal models of stroke and Parkinson's disease. Recently, several studies have shown that the protein Sirtuin 1 (SIRT1) plays a significant role in the induced neuroprotection following dietary restriction. In the present study, we found a significant reduction of SIRT1 levels in the cortex and hippocampus in a mouse model of mild weight-drop closed head TBI. This reduction was prevented in mice maintained on IF (alternate day fasting) and CR initiated after the head trauma. Hippocampus-dependent learning and memory (measured using a novel object recognition test) was impaired 30 days post-injury in mice fed ad libitum, but not in mice in the IF and CR groups. These results suggest a clinical potential for IF and/or CR as an intervention to reduce brain damage and improve functional outcome in TBI patients.

AMP-activated kinase and the endogenous endocannabinoid system might contribute to antinociceptive effects of prolonged moderate caloric restriction in mice

Background

Caloric restriction is associated with broad therapeutic potential in various diseases and an increase in health and life span. In this study, we assessed the impact of caloric restriction on acute and inflammatory nociception in mice, which were either fed ad libitum or subjected to caloric restriction with 80% of the daily average for two weeks.

Results

The behavioral tests revealed that inflammatory nociception in the formalin test and in zymosan-induced mechanical hypersensitivity were significantly decreased when mice underwent caloric restriction. As potential mediators of the diet-induced antinociception, we assessed genes typically induced by inflammatory stimuli, AMP-activated kinase, and the endocannabinoid system which have all already been associated with nociceptive responses. Zymosan-induced inflammatory markers such as COX-2, TNFα, IL-1β, and c-fos in the spinal cord were not altered by caloric restriction. In contrast, AMPKα2 knock-out mice showed significant differences in comparison to C57BL/6 mice and their respective wild type littermates by missing the antinociceptive effects after caloric restriction. Endocannabinoid levels of anandamide and 2-arachidonyl glyceroldetermined in serum by LC-MS/MS were not affected by either caloric restriction alone or in combination with zymosan treatment. However, cannabinoid receptor type 1 expression in the spinal cord, which was not altered by caloric restriction in control mice, was significantly increased after caloric restriction in zymosan-induced paw inflammation. Since increased cannabinoid receptor type 1 signaling might influence AMP-activated kinase activity, we analyzed effects of anandamide on AMP-activated kinase in cell culture and observed a significant activation of AMP-activated kinase. Thus, endocannabionoid-induced AMP-activated kinase activation might be involved in antinociceptive effects after caloric restriction.

Conclusion

Our data suggest that caloric restriction has an impact on inflammatory nociception which might involve AMP-activated kinase activation and an increased activity of the endogenous endocannabinoid system by caloric restriction-induced cannabinoid receptor type 1 upregulation.

Ramadan Fasting Exerts Immunomodulatory Effects: Insights from a Systematic Review

Ramadan is the ninth month of the Islamic lunar calendar and is observed by Muslims as a month of fasting. All Muslim adults are expected to fast; nevertheless certain subgroups, including sick, frail subjects, and pregnant women, among others, are exempted. Ramadan fasting has been shown to impact on body systems in different manners. The influence of Ramadan fasting on immune system regulation remains elusive; however, immune system changes, such as the modulation of body response to various infectious, stressful, and other harmful events, are of great interest during fasting. In this paper, we performed an extensive systematic literature review of different scholarly databases (ISI/Web of Science, Scopus, PubMed,/MEDLINE, Google Scholar, Directory of Open Access Journals, EbscoHOST, Scirus, Science Direct, the Cochrane Library, and ProQuest), using the following key words: "fasting," "Ramadan," "Islam," and "immunity." Conclusions drawn from these findings included: (1) Ramadan fasting has been shown to only mildly influence the immune system and the alterations induced are transient, returning to basal pre-Ramadan status shortly afterward. (2) Ramadan fasting during the second trimester of pregnancy was shown to be safe and did not result in negative fetal outcomes, or maternal oxidative status alterations. (3) In cardiac patients, Ramadan fasting can have beneficial effects including lipid profile improvement and alleviation of oxidative stress. (4) In asthmatic patients as well as in patients with human immunodeficiency virus/acquired immunodeficiency syndrome and autoimmune disorders, fasting was safe. (5) In psychiatric patients, such as those suffering from schizophrenia, fasting could increase immunologic markers. (6) Fasting Muslim athletes who maintain intensive training schedule during Ramadan showed fluctuations of immunologic markers.

Nutrition and fasting mimicking diets in the prevention and treatment of autoimmune diseases and immunosenescence

Complex and coordinated signals are necessary to initiate and sustain the activation, proliferation, and differentiation of lymphocytes. These signals, which are known to determine T-cell fate and function, also depend on the metabolic state of the organism. Recent studies indicate that both the type and levels of nutrients can influence the generation, survival and function of lymphocytes and therefore can affect several autoimmune diseases. Here, we review the dysregulation of lymphocytes during autoimmunity and aging, the mechanisms associated with loss of immune function, and how fasting mimicking diets and other dietary interventions affect autoimmunity and immunosenescence.

Antinociceptive effects of caloric restriction on post-incisional pain in nonobese rats

Caloric restriction (CR) increases lifespan, retards physiological signs of aging, and delays a variety of diseases. Reduction of inflammatory response was proposed as one of the molecular mechanisms for how CR exerts beneficial effects. The present study investigated the effects of CR on postoperative pain in rats. Adult nonobese rats were divided into two dietary groups, an ad libitum fed group (AL) and a caloric restriction group (CR) that was provided with 60% of the food intake of AL rats. After 6 weeks, the effects of CR on pain behaviors and inflammation induced by plantar incision were examined. CR rats displayed significantly reduced nonevoked pain, mechanical allodynia and thermal hyperalgesia induced by incision, and showed decreased levels of pro-inflammatory cytokines in serum, peri-incisional skin tissue and ipsilateral spinal cord dorsal horn at 6 h and 24 h after incision. The analgesic efficiency of parecoxib and morphine, two agents widely used for the management of postoperative pain clinically, was reinforced by CR. Together, CR generates antinociceptive effects on postoperative incisional pain in rats, perhaps providing some improvement of QOL in patients with postoperative pain, and the beneficial effects may be attributable to the inhibition of excessive inflammation induced by surgical injury.

Dietary restriction improves repopulation but impairs lymphoid differentiation capacity of hematopoietic stem cells in early aging

Dietary restriction (DR) improves health, delays tissue aging, and elongates survival in flies and worms. However, studies on laboratory mice and nonhuman primates revealed ambiguous effects of DR on lifespan despite improvements in health parameters. In this study, we analyzed consequences of adult-onset DR (24 h to 1 yr) on hematopoietic stem cell (HSC) function. DR ameliorated HSC aging phenotypes, such as the increase in number of HSCs and the skewing toward myeloid-biased HSCs during aging. Furthermore, DR increased HSC quiescence and improved the maintenance of the repopulation capacity of HSCs during aging. In contrast to these beneficial effects, DR strongly impaired HSC differentiation into lymphoid lineages and particularly inhibited the proliferation of lymphoid progenitors, resulting in decreased production of peripheral B lymphocytes and impaired immune function. The study shows that DR-dependent suppression of growth factors and interleukins mediates these divergent effects caused by DR. Supplementation of insulin-like growth factor 1 partially reverted the DR-induced quiescence of HSCs, whereas IL-6/IL-7 substitutions rescued the impairment of B lymphopoiesis exposed to DR. Together, these findings delineate positive and negative effects of long-term DR on HSC functionality involving distinct stress and growth signaling pathways.

Short-Term Caloric Restriction Suppresses Cardiac Oxidative Stress and Hypertrophy Caused by Chronic Pressure Overload

BACKGROUND

Caloric restriction (CR) prevents senescent changes, in which reactive oxygen species (ROS) have a critical role. Left ventricular (LV) hypertrophy is a risk factor for cardiovascular diseases. We examined whether CR alters cardiac redox state and hypertrophy from chronic pressure overload.

METHODS AND RESULTS

Male c57BL6 mice were subjected to ascending aortic constriction (AAC) with ad libitum caloric intake (AL + AAC group) or 40% restricted caloric intake (CR + AAC group). CR was initiated 2 weeks before AAC and was continued for 4 weeks. Two weeks after constriction, AAC increased LV wall thickness, impaired transmitral flow velocity, and augmented myocyte hypertrophy and fibrosis, in association with enhancement of BNP and collagen III expressions in the AL + AAC group. In the AL + AAC group, oxidative stress in cardiac tissue and mitochondria were enhanced, and NADPH oxidase activity and mitochondrial ROS production were elevated. These changes were significantly attenuated in the CR + AAC group. Additionally, in antioxidant systems, myocardial glutathione peroxidase and superoxide dismutase activities were enhanced in the CR + AAC group.

CONCLUSIONS

Chronic pressure overload increased cardiac oxidative damage, in association with cardiac hypertrophy and fibrosis. Short-term CR suppressed oxidative stress and improved cardiac function, suggesting that short-term CR could be a useful strategy to prevent pressure overload-induced cardiac injury.

Diet, behavior and immunity across the lifespan

It is increasingly appreciated that perinatal events can set an organism on a life-long trajectory for either health or disease, resilience or risk. One early life variable that has proven critical for optimal development is the nutritional environment in which the organism develops. Extensive research has documented the effects of both undernutrition and overnutrition, with strong links evident for an increased risk for obesity and metabolic disorders, as well as adverse mental health outcomes. Recent work has highlighted a critical role of the immune system, in linking diet with long term health and behavioral outcomes. The present review will summarize the recent literature regarding the interactions of diet, immunity, and behavior.

Intermittent fasting attenuates lipopolysaccharide-induced neuroinflammation and memory impairment

BACKGROUND

Systemic bacterial infections often result in enduring cognitive impairment and are a risk factor for dementia. There are currently no effective treatments for infection-induced cognitive impairment. Previous studies have shown that intermittent fasting (IF) can increase the resistance of neurons to injury and disease by stimulating adaptive cellular stress responses. However, the impact of IF on the cognitive sequelae of systemic and brain inflammation is unknown.

METHODS

Rats on IF for 30 days received 1 mg/kg of lipopolysaccharide (LPS) or saline intravenously. Half of the rats were subjected to behavioral tests and the other half were euthanized two hours after LPS administration and the hippocampus was dissected and frozen for analyses.

RESULTS

Here, we report that IF ameliorates cognitive deficits in a rat model of sepsis by a mechanism involving NF-κB activation, suppression of the expression of pro-inflammatory cytokines, and enhancement of neurotrophic support. Treatment of rats with LPS resulted in deficits in cognitive performance in the Barnes maze and inhibitory avoidance tests, without changing locomotor activity, that were ameliorated in rats that had been maintained on the IF diet. IF also resulted in reduced levels of mRNAs encoding the LPS receptor TLR4 and inducible nitric oxide synthase (iNOS) in the hippocampus. Moreover, IF prevented LPS-induced elevation of IL-1α, IL-1β and TNF-α levels, and prevented the LPS-induced reduction of BDNF levels in the hippocampus. IF also significantly attenuated LPS-induced elevations of serum IL-1β, IFN-γ, RANTES, TNF-α and IL-6 levels.

CONCLUSIONS

Taken together, our results suggest that IF induces adaptive responses in the brain and periphery that can suppress inflammation and preserve cognitive function in an animal model of systemic bacterial infection.

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.

Commonly adopted caloric restriction protocols often involve malnutrition

Undernutrition without malnutrition is an intervention that enhances laboratory animal life span, and is widely studied to uncover factors limiting longevity. In a search of the literature over a course of four years, we found that most protocols currently adopted as caloric restriction do not meet micronutrient standards set by the National Research Council for laboratory rats and mice. We provide evidence that the most commonly adopted caloric restriction protocol, a 40% restriction of the AIN-93 diet without vitamin or mineral supplementation, leads to malnutrition in both mice and rats. Furthermore, others and we find that every other day feeding, another dietary intervention often referred to as caloric restriction, does not limit the total amount of calories consumed. Altogether, we propose that the term "caloric restriction" should be used specifically to describe diets that decrease calorie intake but not micronutrient availability, and that protocols adopted should be described in detail in order to allow for comparisons and better understanding of the effects of these diets.

Effects of interleukin-6 treatment on neurovascular function, nerve perfusion and vascular endothelium in diabetic rats

AIM

Interleukin-6 (IL-6), a member of the neuropoietic cytokine family, participates in neural development and has neurotrophic activity. Recent research has also indicated actions to improve vasa nervorum function in diabetes. Both these facets are potentially relevant for treatment of diabetic neuropathy. The aim of this study was to determine whether IL-6 treatment corrected changes in neurovascular function in streptozotocin-induced diabetic rats.

METHODS

After 1 month of diabetes, rats were given IL-6 for 1 month. The rats were subjected to sensory testing and measurements of nerve conduction velocities and nerve blood flow by hydrogen clearance microelectrode polarography. Further groups were used to study responses of the isolated gastric fundus and renal artery. Results were statistically analysed using ANOVA and post hoc tests.

RESULTS

Diabetic rats showed mechanical hyperalgesia, thermal hyperalgesia, and tactile allodynia. The former was unaffected by IL-6 treatment, whereas the latter two measures were corrected. Immunohistochemical staining of dorsal root ganglia for IL-6 did not reveal any changes with diabetes or treatment. The results showed that 22 and 17.4% slowing of sciatic motor and saphenous sensory nerve conduction velocities, respectively, with diabetes were improved by IL-6. Sciatic endoneurial perfusion was halved by diabetes and corrected by IL-6. A 40.6% diabetic deficit in maximal non-adrenergic, non-cholinergic relaxation of gastric fundus to nerve stimulation was unaffected by IL-6. Renal artery endothelium-dependent relaxation was halved by diabetes, the endothelium-derived hyperpolarizing factor (EDHF) component being severely attenuated. IL-6 did not affect nitric oxide-mediated vasorelaxation, but markedly improved EDHF responses.

CONCLUSIONS

IL-6 improved aspects of small and large nerve fibre and vascular endothelium dysfunction in diabetic rats. The functional benefits related to increased nerve blood flow via an EDHF mechanism, and IL-6 could have therapeutic potential in diabetic neuropathy and vasculopathy, which should be further evaluated.

Cytokines and metabolic patterns in pediatric patients with critical illness

It is not known if cytokines, which are cell-derived mediators released during the host immune response to stress, affect metabolic response to stress during critical illness. The aim of this prospective study was to determine whether the metabolic response to stress is related to the inflammatory interleukin-6 (IL-6), 10 (IL-10), and other stress mediators' responses and to assess their relationships with different feeding patterns, nutritional markers, the severity of illness as assessed by the Multiple Organ System Failure (MOSF), the Pediatric Risk of Mortality Score (PRISM), systemic inflammatory response syndrome (SIRS), and mortality in critically ill children. Patients were classified as hypermetabolic, normometabolic, and hypometabolic when the measured resting energy expenditures (REE) were >110%, 90–110% and, <90% of the predicted basal metabolic rate, respectively. The initial predominance of the hypometabolic pattern (48.6%) declined within 1 week of acute stress (20%), and the hypermetabolic patterns dominated only after 2 weeks (60%). Only oxygen consumption (VO₂) and carbon dioxide production (VCO₂) (P < .0001) but none of the cytokines and nutritional markers, were independently associated with a hypometabolic pattern. REE correlated with the IL-10 but not PRISM. In the presence of SIRS or sepsis, CRP, IL-6, IL-10, Prognostic Inflammatory and Nutritional Index (NI), and triglycerides—but not glucose, VO₂, or VCO₂ increased significantly. High IL-10 levels (P = .0000) and low measured REE (P = .0000) were independently associated with mortality (11.7%), which was higher in the hypometabolic compared to other metabolic patterns (P < .005). Our results showed that only VO₂ and VCO₂, but not IL-6 or IL-10, were associated with a hypometabolic pattern which predominated the acute phase of stress, and was associated with increased mortality. Although in SIRS or sepsis, the cytokine response was reliably reflected by increases in NI and triglycerides, it was different from the metabolic (VO₂, VCO₂) or glucose response.

Beneficial effects of dietary restriction in type 2 diabetic rats: the role of adipokines on inflammation and insulin resistance

Inflammation plays an important role in diabetes mellitus and its complications. In this context, the negative cross-talk between adipose tissue and skeletal muscle leads to disturbances in muscle cell insulin signalling and induces insulin resistance. Because several studies have shown that energy restriction brings some benefits to diabetes, the aim of the present study was to evaluate the effects of dietary restriction on systemic and skeletal muscle inflammatory biomarkers, such C-reactive protein, adipokines and cytokines, and in insulin resistance in Goto-Kakizaki rats. This is an animal model of spontaneous non-obese type 2 diabetes with strongly insulin resistance and without dyslipidaemia. Animals were maintained during 2 months of dietary restriction (50 %) and were killed at 6 months of age. Some biochemical determinations were done using ELISA and Western blot. Data from the present study demonstrate that in Goto-Kakizaki rats the dietary restriction improved insulin resistance, NEFA levels and adipokine profile and ameliorated inflammatory cytokines in skeletal muscle. These results indicate that dietary restriction in type 2 diabetes enhances adipose tissue metabolism leading to an improved skeletal muscle insulin sensitivity.

Behavioral and histological assessment of the effect of intermittent feeding in the pilocarpine model of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most resistant type of epilepsy. Currently available drugs for epilepsy are not antiepileptogenic. A novel treatment for epilepsy would be to block or reverse the process of epileptogenesis. We used intermittent feeding (IF) regimen of the dietary restriction (DR) to study its effect on epileptogenesis and neuroprotection in the pilocarpine model of TLE in rats. The effect of IF regimen on the induction of status epilepticus (SE), the duration of latent period, and the frequency, duration, severity and the time of occurrence of Spontaneous Recurrent Seizures (SRS) were investigated. We also studied the effect of IF regimen on hippocampal neurons against the excitotoxic damage of prolonged SE (about 4h) induced by pilocarpine. The animals (Wistar, male, 200-250g) were divided into four main groups: AL-AL (ad libitum diet throughout), AL-IF (PfS) [IF post-first seizure], AL-IF (PSE) [IF post-SE] and IF-IF (IF diet throughout), and two AL and IF control groups. SE was induced by pilocarpine (350mg/kg, i.p.) and with diazepam (6mg/kg, i.p.) injected after 3h, the behavioral signs of SE terminated at about 4h (AL animals, n=29, 260.43+/-8.74min; IF animals, n=19, 224.32+/-20.73min). Behavioral monitoring was carried out by 24h video recording for 3 weeks after the first SRS. Rat brains were then prepared for histological study with Nissl stain and cell counting was done in CA1, CA2 and CA3 regions of the hippocampus. The results show that the animals on IF diet had significantly less SE induction and significantly longer duration of latent period (the period of epileptogenesis) was seen in IF-IF group compared to the AL-AL group. The severity of SRS was significantly more in AL-IF (PfS) compared to the AL-IF (PSE) group. These results indicate that IF diet can make rats resistant to the induction of SE and can prolong the process of epileptogenesis. The results of the histological study show that the number of pyramidal neurons was statistically less in CA1, CA2 and CA3 of the hippocampus in the experimental groups compared to the control groups. However, IF regimen could not protect the hippocampal neurons against the excitotoxic injury caused by a prolonged SE. We conclude that IF regimen can significantly influence various behavioral characteristics of pilocarpine model of TLE. Further studies can elaborate the exact mechanisms as well as its possible role in the treatment of human TLE.

Glucose in the dialysate: historical perspective and possible implications?

Hemodialysate solutions often contain high concentrations of glucose (up to 200 mg/dL). The historical reasons for the addition of glucose to the dialysate included: (1) aid in performance of ultrafiltration and (2) minimization of nutritional (caloric) losses during dialysis. However, recent experimental evidence supports the fact that exposure to high levels of glucose may be pro-inflammatory. Given the high morbidity and mortality associated with dialysis and its linkage to chronic inflammation, the routine use of glucose in the dialysate may warrant reexamination. This review examines the utility of glucose in the dialysate and discusses the potential implications on chronic inflammation in patients with end-stage renal disease. While there is currently no evidence for a casual relationship between dialysate glucose concentration and the chronic inflammation seen in ESRD, this possibility is explored.

The neuroprotective properties of calorie restriction, the ketogenic diet, and ketone bodies

Both calorie restriction and the ketogenic diet possess broad therapeutic potential in various clinical settings and in various animal models of neurological disease. Following calorie restriction or consumption of a ketogenic diet, there is notable improvement in mitochondrial function, a decrease in the expression of apoptotic and inflammatory mediators and an increase in the activity of neurotrophic factors. However, despite these intriguing observations, it is not yet clear which of these mechanisms account for the observed neuroprotective effects. Furthermore, limited compliance and concern for adverse effects hamper efforts at broader clinical application. Recent research aimed at identifying compounds that can reproduce, at least partially, the neuroprotective effects of the diets with less demanding changes to food intake suggests that ketone bodies might represent an appropriate candidate. Ketone bodies protect neurons against multiple types of neuronal injury and are associated with mitochondrial effects similar to those described during calorie restriction or ketogenic diet treatment. The present review summarizes the neuroprotective effects of calorie restriction, of the ketogenic diet and of ketone bodies, and compares their putative mechanisms of action.

Genes regulated by caloric restriction have unique roles within transcriptional networks

Caloric restriction (CR) has received much interest as an intervention that delays age-related disease and increases lifespan. Whole-genome microarrays have been used to identify specific genes underlying these effects, and in mice, this has led to the identification of genes with expression responses to CR that are shared across multiple tissue types. Such CR-regulated genes represent strong candidates for future investigation, but have been understood only as a list, without regard to their broader role within transcriptional networks. In this study, co-expression and network properties of CR-regulated genes were investigated using data generated by more than 600 Affymetrix microarrays. This analysis identified groups of co-expressed genes and regulatory factors associated with the mammalian CR response, and uncovered surprising network properties of CR-regulated genes. Genes downregulated by CR were highly connected and located in dense network regions. In contrast, CR-upregulated genes were weakly connected and positioned in sparse network regions. Some network properties were mirrored by CR-regulated genes from invertebrate models, suggesting an evolutionary basis for the observed patterns. These findings contribute to a systems-level picture of how CR influences transcription within mammalian cells, and point towards a comprehensive understanding of CR in terms of its influence on biological networks.

Effect of weight loss on some serum cytokines in human obesity: increase in IL-10 after weight loss

Obesity is a major risk factor for hypertension, coronary artery disease and type 2 diabetes. Weight loss is associated with significant metabolic benefits. Our objective was to examine changes in adipocytokines and interleukin (IL) 10 in obese subjects before and after weight loss. We measured anthropometric parameters, adipocytokine and IL-10 in 78 obese people who had visited obesity clinics at five university hospitals (Ajou, Ulsan, Catholic, Hanyang and Yonsei) in Korea. They restricted their caloric intake to less than their usual intake (by 500 kcal), were administered sibutramine and were given a program of exercise for 12 weeks. After 12 weeks, weight, body mass index, waist circumference, hip circumference, waist-to-hip ratio, total body fat, total cholesterol, triglyceride, tumor necrosis factor alpha (TNF-alpha), IL-6, resistin and leptin had significantly decreased, while adiponectin and IL-10 had significantly increased. A bivariate correlation analysis found that increment in IL-10 and baseline IL-10 levels significantly correlated with decrement in TNF-alpha (P<.01) and baseline adiponectin (r=.52, P<.001), respectively. These results were confirmed in a multiple regression analysis. The results suggest that weight loss after caloric restriction and medical treatment in obesity can improve metabolic risk factors through changes in some cytokines.

TNF-alpha and adipocyte biology

Dyslipidemia and insulin resistance are commonly associated with catabolic or lipodystrophic conditions (such as cancer and sepsis) and with pathological states of nutritional overload (such as obesity-related type 2 diabetes). Two common features of these metabolic disorders are adipose tissue dysfunction and elevated levels of tumour necrosis factor-alpha (TNF-alpha). Herein, we review the multiple actions of this pro-inflammatory adipokine on adipose tissue biology. These include inhibition of carbohydrate metabolism, lipogenesis, adipogenesis and thermogenesis and stimulation of lipolysis. TNF-alpha can also impact the endocrine functions of adipose tissue. Taken together, TNF-alpha contributes to metabolic dysregulation by impairing both adipose tissue function and its ability to store excess fuel. The molecular mechanisms that underlie these actions are discussed.

Transcriptome analysis of age-, gender- and diet-associated changes in murine thymus

The loss of thymic function with age may be due to diminished numbers of T-cell progenitors and the loss of critical mediators within the thymic microenvironment. To assess the molecular changes associated with this loss, we examined transcriptomes of progressively aging mouse thymi, of different sexes and on caloric-restricted (CR) vs. ad libitum (AL) diets. Genes involved in various biological and molecular processes including transcriptional regulators, stress response, inflammation and immune function significantly changed during thymic aging. These differences depended on variables such as sex and diet. Interestingly, many changes associated with thymic aging are either muted or almost completely reversed in mice on caloric-restricted diets. These studies provide valuable insight into the molecular mechanisms associated with thymic aging and emphasize the need to account for biological variables such as sex and diet when elucidating the genomic correlates that influence the molecular pathways responsible for thymic involution.