Blood Corticosterone Concentration Reaches Critical Illness Levels Early During Acute Malnutrition in the Weanling Mouse

The Tolerance Model of Non-Inflammatory Immune Competence in Acute Pediatric Malnutrition: Origins, Evidence, Test of Fitness and Growth Potential

The tolerance model rests on the thesis of a physiologically regulated, albeit unsustainable, systemic attempt to adapt to the catabolic challenge posed by acute prepubescent malnutrition even in its severe forms. The model centers on the immunological component of the attempt, positing reorientation toward a non-inflammatory form of competence in place of the classic paradigm of immunological attrition and exhaustion. The foundation of the model was laid in 1990, and sixteen years later it was articulated formally on the basis of a body of evidence centered on T cell cytokines and interventions with cytokine and hormonal mediators. The benefit originally suggested was a reduced risk of autoimmune pathologies consequent to the catabolic release of self-antigens, hence the designation highlighting immune tolerance. Herein, the emergence of the tolerance model is traced from its roots in the recognition that acute malnutrition elicits an endocrine-based systemic adaptive attempt. Thereafter, the growth of the evidence base supporting the model is outlined, and its potential to shed new light on existing information is tested by application to the findings of a published clinical study of acutely malnourished children. Finally, some knowledge gaps pertinent to the model are identified and its potential for growth consonant with evolving perceptions of immunobiology is illustrated.

Geriatric Nutrition Risk Index as a predictor of cardiovascular and all-cause mortality in older Americans with diabetes

BACKGROUND AND AIMS

Few studies have examined the relationship between malnutrition, as defined by the Geriatric Nutrition Risk Index (GNRI), and all-cause mortality and cardiovascular mortality events, particularly in persons with diabetes. The study aimed at the association between GNRI and all-cause mortality and cardiovascular mortality in older Americans with diabetes.

METHODS

Data from this retrospective study were obtained from the National Health and Nutrition Examination (NHANES) 1999-2016. Using data from The NHANES Public-Use Linked Mortality Files to assess all-cause mortality (ACM) and cardiovascular mortality (CVM). After excluding participants younger than 60 years and without diabetes, and with missing follow-up data, 4400 cases were left in this study. Persons with diabetes were divided by GNRI into 3 groups: GNRI ≥ 98; 92 ≤ GNRI < 98; and GNRI < 92; (No; Low; Moderate/Severe (M/S) group). We used Cox proportional hazard regression model to explore the predictive role of GNRI on ACM and CVM in elderly persons with diabetes. Restricted cubic splines to investigate the existence of a dose-response linear relationship between them.

RESULT

During a median follow-up period of 89 months, a total of 538 (12.23%) cardiovascular deaths occurred and 1890 (42.95%) all-cause deaths occurred. Multifactorial COX regression analysis showed all-cause mortality (hazard ratio [HR]: 2.58, 95% CI: 1.672-3.994, p < 0.001) and cardiovascular mortality (HR: 2.29, 95% CI: 1.063-4.936, p = 0.034) associated with M/S group risk of malnutrition in GNRI compared to no group. A negative association between GNRI and all-cause mortality was observed across gender and ethnicity. However, the same negative association between GNRI and cardiovascular mortality was observed only for males (HR:0.94, 95% CI:0.905-0.974, p < 0.001) and other races (HR:0.92, 95% CI:0.861-0.976, p = 0.007). And there was no significant correlation between low malnutrition and cardiovascular mortality (p = 0.076). Restricted cubic splines showed a nonlinear relationship between GNRI and all-cause mortality and cardiovascular mortality (non-linear p < 0.001, non-linear p = 0.019).

CONCLUSIONS

Lower GNRI levels are associated with mortality in older patients with diabetes. GNRI may be a predictor of all-cause mortality and cardiovascular mortality risk in older patients with diabetes.

Thymus, undernutrition, and infection: Approaching cellular and molecular interactions

Undernutrition remains a major issue in global health. Low protein-energy consumption, results in stunting, wasting and/or underweight, three deleterious forms of malnutrition that affect roughly 200 million children under the age of five years. Undernutrition compromises the immune system with the generation of various degrees of immunodeficiency, which in turn, renders undernourished individuals more sensitive to acute infections. The severity of various infectious diseases including visceral leishmaniasis (VL), influenza, and tuberculosis is associated with undernutrition. Immunosuppression resulting from protein-energy undernutrition severely impacts primary and secondary lymphoid organs involved in the response to related pathogens. The thymus-a primary lymphoid organ responsible for the generation of T lymphocytes-is particularly compromised by both undernutrition and infectious diseases. In this respect, we will discuss herein various intrathymic cellular and molecular interactions seen in undernutrition alone or in combination with acute infections. Many examples illustrated in studies on humans and experimental animals clearly revealed that protein-related undernutrition causes thymic atrophy, with cortical thymocyte depletion. Moreover, the non-lymphoid microenvironmental compartment of the organ undergoes important changes in thymic epithelial cells, including their secretory products such as hormones and extracellular matrix proteins. Of note, deficiencies in vitamins and trace elements also induce thymic atrophy. Interestingly, among the molecular interactions involved in the control of undernutrition-induced thymic atrophy is a hormonal imbalance with a rise in glucocorticoids and a decrease in leptin serum levels. Undernutrition also yields a negative impact of acute infections upon the thymus, frequently with the intrathymic detection of pathogens or their antigens. For instance, undernourished mice infected with Leishmania infantum (that causes VL) undergo drastic thymic atrophy, with significant reduction in thymocyte numbers, and decreased levels of intrathymic chemokines and cytokines, indicating that both lymphoid and microenvironmental compartments of the organ are affected. Lastly, recent data revealed that some probiotic bacteria or probiotic fermented milks improve the thymus status in a model of malnutrition, thus raising a new field for investigation, namely the thymus-gut connection, indicating that probiotics can be envisioned as a further adjuvant therapy in the control of thymic changes in undernutrition accompanied or not by infection.

Edible insects prevent changes to brain monoamine profiles from malnourishment in weaned rats

Background: Childhood malnutrition can have devastating consequences on health, behavior, and cognition. Edible insects are sustainable low cost high protein and iron nutritious foods that can prevent malnutrition. However, it is unclear whether insect-based diets may help prevent changes to brain neurochemistry associated with malnutrition.Materials and Methods: Weanling male Sprague-Dawley rats were malnourished by feeding a low protein-iron diet (LPI, 5% protein and ∼2 ppm Fe) for 3 weeks or nourished by feeding a sufficient protein-iron diet (SPI, 15% protein 20 ppm FeSO₄) for the duration of the study. Following 3 weeks of LPI diet, three subsets of the malnourished rats were placed on repletion diets supplemented with cricket, palm weevil larvae, or the SPI diet for 2 weeks, while the remaining rats continued the LPI diet for an additional 2 weeks. Monoamine-related neurochemicals (e.g. serotonin (5-HT), dopamine (DA), norepinephrine) and select monoamine metabolites were measured in the hypothalamus, hippocampus, striatum, and prefrontal cortex using Ultra High-Performance Liquid Chromatography.Results: Five weeks of LPI diets disrupted brain monoamines, most notable in the hypothalamus. Two weeks supplementation with cricket and palm weevil larvae diets prevented changes to measures of 5-HT and DA turnover in the hippocampus and hypothalamus. Moreover, these insect diets prevented the malnutrition-induced imbalance of 5-HT and DA metabolites in the hippocampus, striatum, and hypothalamus.Conclusion: Edible insects such as cricket and palm weevil larvae could be sustainable nutrition intervention to prevent behavioral and cognitive impairment associated abnormal brain monoamine activities that results from early life malnutrition.

Elevated Bioactivity of the Tolerogenic Cytokines, Interleukin-10 and Transforming Growth Factor-β, in the Blood of Acutely Malnourished Weanling Mice

The main objective of this investigation was to determine the influence of acute deficits of protein and energy on the blood levels of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), physiologically the main anti-inflammatory and tolerogenic cytokines. In four 14-day experiments, male and female C57BL/6J mice, initially 19 days old, consumed a complete purified diet either ad libitum or in restricted daily quantities, or had free access to an isocaloric purified low-protein diet. A zero-time control group (19 days old) was included. In the first two experiments, serum IL-10 levels were assessed by sandwich enzyme-linked immunosorbent assay (ELISA) and bioassay. The mean serum IL-10 bioactivities were higher (P ≤ 0.05) in both malnourished groups (low-protein and restricted intake: 15.8 and 12.2 ng/ml, respectively) than in the zero-time and age-matched control groups (6.3 and 7.3 ng/ml, respectively), whereas serum IL-10 immunoactivity was high only in the restricted intake group (e.g., second experiment: 17.0 pg/ml vs. 5.4, 3.7, and 3.1 pg/ml in the zero-time control, age-matched control and low-protein group, respectively). The third and fourth experiments centered on plasma TGF-β immunoactivity (sandwich ELISA) and bioactivity, respectively. The ELISA revealed a high mean plasma TGF-β1 level (P < 0.05) in the low-protein group only, but TGF-β bioactivity (β1 isoform, although 15% β2 in the restricted intake group) was high in both malnourished groups (8.7 and 9.3 ng/ml in the low-protein and restricted groups, respectively) relative to the age-matched control group (0.5 ng/ml). Thus, metabolically distinct weanling systems mimicking marasmus and incipient kwashiorkor both exhibit a blood cytokine profile that points to a tolerogenic microenvironment within immune response compartments. A model emerges in which malnutrition-associated immune competence, at least in advanced weight loss, centers on cytokine-mediated peripheral tolerance that reduces the risk of catabolically induced autoimmune disease, but this is at the cost of attenuated responsiveness to infectious agents.

Protein-Energy Malnutrition Causes Deficits in Motor Function in Adult Male Rats

BACKGROUND

Adult protein-energy malnutrition (PEM) often occurs in combination with neurological disorders affecting hand use and walking ability. The independent effects of PEM on motor function are not well characterized and may be obscured by these comorbidities.

OBJECTIVE

Our goal was to undertake a comprehensive evaluation of sensorimotor function with the onset and progression of PEM in an adult male rat model.

METHODS

In Expt. 1 and Expt. 2, male Sprague-Dawley rats (14-15 wk old) were assigned ad libitum access for 4 wk to normal-protein (NP) or low-protein (LP) diets containing 12.5% and 0.5% protein, respectively. Expt. 1 assessed muscle strength, balance, and skilled walking ability on days 2, 8, and 27 by bar-holding, cylinder, and horizontal ladder walking tasks, respectively. In addition to food intake and body weight, nutritional status was determined on days 3, 9, and 28 by serum acute-phase reactant and corticosterone concentrations and liver lipids. Expt. 2 addressed the effect of an LP diet on hindlimb muscle size.

RESULTS

PEM evolved over time in rats consuming the LP diet. Total food intake decreased by 24% compared with the NP group. On day 28, body weight and serum albumin decreased by 31% and 26%, respectively, and serum α2-macroglobulin increased by 445% (P < 0.05) in the LP group compared with the NP group. Forelimb dysfunction (173% increase in adaptive flexed-arm-hang score) developed on day 2 in rats fed the LP diet (P < 0.001), whereas abnormal walking (34% decreased incidence of correct hindlimb placement) developed by day 27 (P < 0.05). Relative to the NP diet, the LP diet reduced the cross-sectional area of gastrocnemius medialis (P < 0.05).

CONCLUSIONS

PEM in adult male rats causes a variety of sensorimotor abnormalities that develop at different stages of malnutrition. This model can be used in combination with disease models of sensorimotor deficits to examine the interactions between nutritional status, other treatments, and disease progression.

The influence of vitamin B12 supplementation on the level of white blood cells and lymphocytes phenotype in rats fed a low-protein diet

Protein malnutrition has a negative effect on body composition and some blood parameters, especially in the young growing organism. One of nutritional factors which could protect against negative consequences of protein deficiency may be B group vitamins. The aim of the study was to investigate the effect of vitamin B12 supplementation on the immune system in rats fed a standard and a low-protein diet. Rats were fed a control (20% of energy from protein) or a protein-deficient diet (4.5% of energy from protein). Half of animals in each group were additionally supplemented with vitamin B12 (300% of the daily intake). The white blood cells analysis and lymphocytes immunophenotyping (number and percentage) were performed. Low-protein diets caused disturbances in WBC and lymphocyte subpopulations in both short- (30-day) as well as long-term periods (90-day). Vitamin B12 supplementation significantly reduced the negative impact of protein malnutrition after 30 days, however had no effect on long-term malnutrition. Furthermore, vitamin B12 addition in rats fed a control diet did not affect the studied parameters. This observation opens the promise of use of vitamin B12 supplementation to improve immune system parameters in protein malnourished organisms.

Ribosome abundance regulates the recovery of skeletal muscle protein mass upon recuperation from postnatal undernutrition in mice

Nutritionally-induced growth faltering in the perinatal period has been associated with reduced adult skeletal muscle mass; however, the mechanisms responsible for this are unclear. To identify the factors that determine the recuperative capacity of muscle mass, we studied offspring of FVB mouse dams fed a protein-restricted diet during gestation (GLP) or pups suckled from postnatal day 1 (PN1) to PN11 (E-UN), or PN11 to PN22 (L-UN) on protein-restricted or control dams. All pups were refed under control conditions following the episode of undernutrition. Before refeeding, and 2, 7 and 21 days later, muscle protein synthesis was measured in vivo. There were no long-term deficits in protein mass in GLP and E-UN offspring, but in L-UN offspring muscle protein mass remained significantly smaller even after 18 months (P < 0.001). E-UN differed from L-UN offspring by their capacity to upregulate postprandial muscle protein synthesis when refed (P < 0.001), a difference that was attributable to a transient increase in ribosomal abundance, i.e. translational capacity, in E-UN offspring (P < 0.05); translational efficiency was similar across dietary treatments. The postprandial phosphorylation of Akt and extracellular signal-regulated protein kinases were similar among treatments. However, activation of the ribosomal S6 kinase 1 via mTOR (P < 0.02), and total upstream binding factor abundance were significantly greater in E-UN than L-UN offspring (P < 0.02). The results indicate that the capacity of muscles to recover following perinatal undernutrition depends on developmental age as this establishes whether ribosome abundance can be enhanced sufficiently to promote the protein synthesis rates required to accelerate protein deposition for catch-up growth.

Dietary zinc deficiency in rodents: effects on T-cell development, maturation and phenotypes

Zinc deficiency is one of the leading risk factors for developing disease and yet we do not have a clear understanding of the mechanisms behind the increased susceptibility to infection. This review will examine the interrelationships among the hypothalamus-pituitary-adrenal stress axis, p56^lck, and T-cell maturation in both zinc deficiency and responses during zinc repletion. We will highlight differences between the adult mouse model (wasting malnutrition) and growing rat model (stunting malnutrition) of dietary zinc deficiency and discuss the use of various controls to separate out the effects of zinc deficiency from the associated malnutrition. Elevated serum corticosterone in both zinc deficient and pair-fed rats does not support the hypothesis that zinc deficiency per se leads to corticosterone-induced apoptosis and lymphopenia. In fact, the zinc deficient rat does not have lymphopenia. Thymocytes from zinc deficient mice and rats have elevated levels of p56^lck, a signalling protein with a zinc clasp structure, but this does not appear to affect thymocyte maturation. However, post-thymic T-cell maturation appears to be altered based on the lower proportion of splenic late thymic emigrants in zinc deficient rats. Fewer new T-cells in the periphery could adversely affect the T-cell repertoire and contribute to immunodeficiency in zinc deficiency.

A non-inflammatory form of immune competence prevails in acute pre-pubescent malnutrition: new evidence based on critical mRNA transcripts in the mouse

The declining inflammatory immune competence of acute (i.e. wasting) pre-pubescent protein-energy malnutrition has been regarded as reflecting an unregulated immunological disintegration. Recent evidence, however, suggests that malnutrition stimulates a regulated immunological reconfiguration to achieve a non-inflammatory form of competence, perhaps offering protection against autoimmune reactions - the 'Tolerance Model'. Our objective was to determine the influence of acute pre-pubescent malnutrition on the expression of genes critical to tolerogenic regulation. Male and female C57BL/6J mice, initially 19 d old, consumed a complete purified diet either ad libitum (age-matched controls) or in restricted daily quantities (mimicking marasmus), or consumed an isoenergetic low-protein diet ad libitum (mimicking incipient kwashiorkor) for 14 d (six animals per dietary group). Gene expression in the spleen, typically an inflammatory organ, and in the small intestine, a site designed for non-inflammatory defence, was assessed by real-time quantitative RT-PCR, and normalised to β-actin. In the spleen of the malnourished groups, both IL-10 and transforming growth factor-β1 mRNA expression increased compared with controls (P < 0.05), whereas mRNA expression of IL-12p40 decreased (P < 0.05). Conversely, malnutrition exerted no influence on the expression of mRNA for these cytokines in the small intestine (P>0.05). Moreover, forkhead box P3 mRNA expression, indicative of cell-based tolerogenic potential, was sustained in both the spleen and intestine of the malnourished groups (P>0.05). Thus, despite limited supplies of energy and substrates, the spleen shifted towards a non-inflammatory character and the intestine was sustained in this mode in advanced pre-pubescent weight loss. These findings provide the first support for the Tolerance Model at the level of mRNA transcript expression.

RU486 (mifepristone) ameliorates cognitive dysfunction and reverses the down-regulation of astrocytic N-myc downstream-regulated gene 2 in streptozotocin-induced type-1 diabetic rats

Diabetic cognitive dysfunction (DCD), usually accompanied with chronically elevated glucocorticoids and hippocampal astrocytic alterations, is one of the most serious complications in patients with type-1 diabetes. However, the role for chronically elevated glucocorticoids and hippocampal astrocytic activations in DCD remains to be elucidated, and it is not clear whether astrocytic N-myc downstream-regulated gene 2 (NDRG2, involved in cell differentiation and development) participated in DCD. In the present study, three months after streptozotocin (STZ)-induced type-1 diabetes onset, rats showed cognitive impairments in Morris water maze test as well as elevated corticosterone level. Diabetic rats also presented down-regulation of glial fibrillary acidic protein (GFAP, a key indicator of astrocytic reactivity) and NDRG2 in hippocampus revealed by immunohistochemistry staining, real-time PCR and Western blot. Moreover, the diabetic cognitive impairments were ameliorated by 9-day glucocorticoids receptor (GR) blockade with RU486, and the down-regulation of hippocampal NDRG2 and GFAP in diabetic animals was also attenuated by 9-day GR blockade. These results suggest that glucocorticoids-GR system is crucial for DCD, and that astrocytic reactivity and NDRG2 are involved in these processes. Thus, inhibiting GR activation in the hippocampus may be a novel therapeutic strategy for treating DCD.

Constitutive, but not challenge-induced, interleukin-10 production is robust in acute pre-pubescent protein and energy deficits: new support for the tolerance hypothesis of malnutrition-associated immune depression based on cytokine production in vivo

The tolerance model of acute (i.e., wasting) pre-pubescent protein and energy deficits proposes that the immune depression characteristic of these pathologies reflects an intact anti-inflammatory form of immune competence that reduces the risk of autoimmune reactions to catabolically released self antigens. A cornerstone of this proposition is the finding that constitutive (first-tier) interleukin(IL)-10 production is sustained even into the advanced stages of acute malnutrition. The IL-10 response to inflammatory challenge constitutes a second tier of anti-inflammatory regulation and was the focus of this investigation. Weanling mice consumed a complete diet ad libitum, a low-protein diet ad libitum (mimicking incipient kwashiorkor), or the complete diet in restricted daily quantities (mimicking marasmus), and their second-tier IL-10 production was determined both in vitro and in vivo using lipopolysaccharide (LPS) and anti-CD3 as stimulants of innate and adaptive defences, respectively. Both early (3 days) and advanced (14 days) stages of wasting pathology were examined and three main outcomes emerged. First, classic in vitro systems are unreliable for discerning cytokine production in vivo. Secondly, in diverse forms of acute malnutrition declining challenge-induced IL-10 production may provide an early sign that anti-inflammatory control over immune competence is failing. Thirdly, and most fundamentally, the investigation provides new support for the tolerance model of malnutrition-associated inflammatory immune depression.

Inhibition of PTP1B by trodusquemine (MSI-1436) causes fat-specific weight loss in diet-induced obese mice

Trodusquemine (MSI-1436) causes rapid and reversible weight loss in genetic models of obesity. To better predict the potential effects of trodusquemine in the clinic, we investigated the effects of trodusquemine treatment in a murine model of diet-induced obesity (DIO). Trodusquemine suppressed appetite, reduced body weight (BW) in a fat-specific manner, and improved plasma insulin and leptin levels in mice. Screening assays revealed that trodusquemine selectively inhibited protein-tyrosine phosphatase 1B (PTP1B), a key enzyme regulating insulin and leptin signaling. Trodusquemine significantly enhanced insulin-stimulated tyrosine phosphorylation of insulin receptor (IR) beta and STAT3, direct targets of PTP1B, in HepG2 cells in vitro and/or hypothalamic tissue in vivo. These data establish trodusquemine as an effective central and peripheral PTP1B inhibitor with the potential to elicit noncachectic fat-specific weight loss and improve insulin and leptin levels.

The blood level of transforming growth factor-β rises in the early stages of acute protein and energy deficit in the weanling mouse

Plasma transforming growth factor (TGF)-β levels are high in the advanced stages of acute (wasting) pre-pubescent deficits of protein and energy. Consequently, this potently anti-inflammatory cytokine may help to sustain the depression of inflammatory immune competence in acute malnutrition. Our objective was to determine if plasma TGF-β levels rise during the early stages of acute malnutrition and, secondarily, to confirm the elevation reported previously in advanced weight loss. In two experiments, male and female C57BL/6J mice, initially 19 d old, consumedad libituma complete purified diet (group C), or in restricted daily quantities (group R) or had free access to an isoenergetic low-protein diet (group LP). TGF-β bioactivity in platelet-poor plasma was determined via inhibition of Mv1Lu mink lung cell proliferation after 3 d (Expt 1, early stage) or 14 d (Expt 2, advanced stage) of dietary intervention. At 3 d, mean plasma TGF-β bioactivities were 802 (C), 2952 (R) and 4678 (LP) pg/ml, and after 14 d mean bioactivities were 1786 (C), 5360 (R) and 5735 (LP) pg/ml. At both time points, the malnourished groups differed from age-matched controls (P ≤ 0·05). Thus, metabolically distinct weanling systems mimicking paediatric marasmus (group R) and kwashiorkor (group LP) exhibit an early rise in blood TGF-β concentration, and this cytokine joins corticosterone and IL-10 as a third anti-inflammatory hormone temporally positioned to contribute to the initiation (and maintenance) of malnutrition-associated immune depression. This investigation contributes new insight into the active anti-inflammatory form of immune competence that appears to prevail in acute pre-pubescent malnutrition.

Effects of early malnutrition on mental system, metabolic syndrome, immunity and the gastrointestinal tract

The notion of how malnutrition early in life affects ontogenesis has evolved considerably since the mid-1960s. Since then, there have been many studies on the effects of early malnutrition. Nutritional and metabolic exposure during critical periods in early human and animal development may have long-term programming effects in adulthood. This is supported by evidence from epidemiological studies, numerous animal models and clinical intervention trials. In this paper, we review the effects of early malnutrition on cognitive function, metabolic syndrome, immunity and the gastrointestinal tract, as well as possible underlying mechanisms, and consider diarrhoeal disease and poor cognitive function as examples for understanding the interrelation of the harmful effects caused by early malnutrition. Previous studies on early malnutrition have mainly concentrated on humans and rats. Therefore, the main aim of the present review was to give animal scientists a clear understanding of the harmful effects of early malnutrition on animal growth and animal production, and to help identify appropriate feeding techniques to prevent early malnutrition.

Elevated blood interleukin-10 levels and undiminished systemic interleukin-10 production rate prevail throughout acute protein-energy malnutrition in the weanling mouse

The objectives were to determine if blood IL-10 levels rise during the early stages of acute (wasting) pre-pubescent malnutrition in metabolically distinct murine models known to depress inflammatory immune competence and whether systemic IL-10 production is affected in these pathologies. Weanling C57BL/6J mice were assigned to dietary protocols that elicited wasting pathologies mimicking the human diseases of marasmus (restricted-intake group) or incipient kwashiorkor (low-protein group). An age-matched control group also was included. Serum IL-10 bioactivities were assessed in the early (day 3) and advanced (day 14) stages of weight loss, and net systemic IL-10 production was assessed at the same stages of pathology by in vivo cytokine capture. Blood IL-10 levels were elevated in both malnourished groups relative to controls at days 3 and 14 (range of P values: 0.03-0.0001). Further, despite a limited supply of energy and nitrogenous substrates, the systemic IL-10 production rate was at least sustained in the malnourished groups and, in fact, was elevated in the marasmic group (P=0.05) throughout the progression of weight loss. IL-10 emerges as an anti-inflammatory mediator positioned to participate in initiating and upholding the depressed immune competence that accompanies acute pre-pubescent deficits of protein and energy.

Behavior in the forced swim test and neurochemical changes in the hippocampus in young rats after 2-week zinc deprivation

Abnormal behavior in zinc deficiency and its cause are poorly understood. In the present paper, behavior in the forced swim test and neurochemical changes in the brain associated with its behavior were studied focused on abnormal corticosterone secretion in zinc deficiency. The effect of chronic corticosterone treatment was also studied. Immobility time in the forced swim test was increased in young rats fed a zinc-deficient diet for 2 weeks, as well as corticosterone (40mg/kg/dayx14 days)-treated control rats. The basal Ca(2+) levels in the hippocampus, which were determined by fluo-4FF, AM, were increased in both brain slices from zinc-deficient and corticosterone-treated rats. Serum glucose level was decreased in zinc deficiency and hippocampal glucose metabolism, which is determined by [(14)C]2-deoxyglucose uptake, was elevated. Hippocampal ATP level was not decreased, whereas, the concentrations of glutamate, GABA and glutamine in the hippocampus, unlike the whole brain, were decreased in zinc deficiency. However, the decrease in these amino acids was restored by adrenalectomy prior to zinc deficiency. These results suggest that glucose is insufficient for the synthesis of amino acids in the hippocampus of zinc-deficient rats. It is likely that the neurochemical and metabolic changes in the hippocampus, which may be associated with abnormal corticosterone secretion, is the base of abnormal behavior associated with neuropsychological symptoms in zinc deficiency.

Malnutrition alters the rates of apoptosis in splenocytes and thymocyte subpopulations of rats

Malnutrition continues to be a major public health problem throughout the developing world. Nutritional deficiencies may be the most common cause of secondary immunodeficiency states in humans. It has been suggested that nutritional imbalances can induce apoptosis in a variety of cell types. The purpose of this study was to examine the effect of severe malnutrition on cell subsets and the frequency of spontaneous and/or dexamethasone-induced cell death in vivo in the thymus and spleen from severely malnourished, lactating rats. Apoptosis frequency was estimated by flow cytometry using annexin-V and terminal transferase-mediated dUTP nick-end labelling assay assays. The results obtained in the present study indicate that malnutrition is associated with a significant increase of spontaneously apoptotic cells in the thymus (9.8-fold) and spleen (2.4-fold). Increase in apoptosis was associated largely with CD4(+)CD8(+) double-positive thymocytes. Unexpectedly, similar frequencies of spontaneous apoptosis of these cells were found in both well-nourished and malnourished rats. In contrast, consistent increases in the apoptosis of CD4(-)CD8(-) double-negative thymocytes were observed in malnourished rats. In addition, single-positive CD8(+) and single-positive CD4(+) thymocytes had higher frequencies of apoptosis in malnourished rats. The frequency of total dexamethasone-induced apoptosis was found to be similar in both groups of animals. Nevertheless, in malnourished dexamethasone-treated animals, the percentage of apoptotic double-negative thymocytes was significantly higher than in well-nourished animals, while the rate of apoptosis was lower among double-positive cells. In general, the thymus appears more sensitive to the effects of malnutrition and dexamethasone than the spleen. Furthermore, double-negative thymocytes appear to be the most affected.

Protein-energy malnutrition increases activation of the transcription factor, nuclear factor kappaB, in the gerbil hippocampus following global ischemia

Protein-energy malnutrition (PEM) exacerbates functional impairment caused by brain ischemia. This is correlated with reactive gliosis, which suggests an increased inflammatory response. The objective of the current study was to investigate if PEM increases hippocampal activation of nuclear factor kappaB (NFkappaB), a transcription factor that amplifies the inflammatory response involved in ischemic brain injury. Mongolian gerbils (11-12 weeks old) were randomly assigned to control diet (12.5% protein) or protein-deficient diet (2%) for 4 weeks. The 2% protein group had a 15% decrease in voluntary food intake (P<.001; unpaired t test), resulting in PEM. Body weight after 4 weeks was 20% lower in the PEM group (P<.001). Gerbils were then exposed to sham surgery or global ischemia induced by 5-min bilateral common carotid artery occlusion. PEM independently increased hippocampal NFkappaB activation detected by electrophoretic mobility shift assay at 6 h after surgery (P=.014; 2-factor ANOVA). Ischemia did not significantly affect NFkappaB activation nor was there interaction between diet and ischemia. Serum glucose and cortisol concentrations at 6 h postischemia were unaltered by diet or ischemia. A second experiment using gerbils of the same age and feeding paradigm demonstrated that PEM also increases hippocampal NFkappaB activation in the absence of surgery. These findings suggest that PEM, which exists in 16% of elderly patients at admission for stroke, may worsen outcome by increasing activation of NFkappaB. Since PEM increased NFkappaB activation independent of ischemia or surgery, the data also have implications for the inflammatory response of the many individuals affected globally by PEM.

Adoptively transferred dendritic cells restore primary cell-mediated inflammatory competence to acutely malnourished weanling mice

Immune depression associated with prepubescent malnutrition underlies a staggering burden of infection-related morbidity. This investigation centered on dendritic cells as potentially decisive in this phenomenon. C57BL/6J mice, initially 19 days old, had free access for 14 days to a complete diet or to a low-protein formulation that induced wasting deficits of protein and energy. Mice were sensitized by i.p. injection of sheep red blood cells on day 9, at which time one-half of the animals in each dietary group received a simultaneous injection of 10(6) syngeneic dendritic cells (JAWS II). All mice were challenged with the immunizing antigen in the right hind footpad on day 13, and the 24-hour delayed hypersensitivity response was assessed as percentage increase in footpad thickness. The low-protein diet reduced the inflammatory immune response, but JAWS cells, which exhibited immature phenotypic and functional characteristics, increased the response of both the malnourished group and the controls. By contrast, i.p. injection of 10(6) syngeneic T cells did not influence the inflammatory immune response of mice subjected to the low-protein protocol. Antigen-presenting cell numbers limited primary inflammatory cell-mediated competence in this model of wasting malnutrition, an outcome that challenges the prevailing multifactorial model of malnutrition-associated immune depression. Thus, a new dendritic cell-centered perspective emerges regarding the cellular mechanism underlying immune depression in acute pediatric protein and energy deficit.

Interferons and the maternal-conceptus dialog in mammals

Two-way communication between the conceptus and the mother during early pregnancy is essential if the pregnancy is to survive. In this review, our primary focus is on biochemical communication between the conceptus and mother in the ruminant ungulate species. We emphasize, in particular, the role played by interferon-tau (IFNT) in triggering maternal responses in cattle and sheep and how maternal factors intervene to up-regulate IFNT gene (IFNT) expression in trophoblast. However, we also consider the possibility that different signaling cytokines or the physical presence of trophoblast may induce a partial IFN response in endometrium of those species where there is no evidence for large scale trophoblast IFN production. Conceivably, disparate signaling mechanisms trigger common downstream events necessary to secure a successful pregnancy.

Malnutrition and infection: complex mechanisms and global impacts

The authors discuss current concepts and controversies surrounding the complex influences of malnutrition on infection and immunity, and point to practical consequences of countermeasures in acute malnutrition.