Immune and hormonal regulation of the Boa constrictor (Serpentes; Boidae) in response to feeding.

Feeding upregulates immune function and the systemic and local (gastrointestinal tract) concentrations of some immunoregulatory hormones, as corticosterone (CORT) and melatonin (MEL), in mammals and anurans. However, little is known about the immune and hormonal regulation in response to feeding in other ectothermic vertebrates, especially snakes, in which the postprandial metabolic changes are pronounced. Here, we investigated the effects feeding have on hormonal and innate immune responses in the snake, Boa constrictor. We divided juvenile males into two groups: fasting and fed with mice (30% of body mass). We measured the rates of oxygen consumption, plasma CORT levels, heterophil/lymphocyte ratio (HL ratio), plasma bacterial killing ability (BKA), and stomach and intestine MEL in fasting snakes and 48 h after meal intake. We observed increased rates of oxygen consumption, plasma CORT levels, and HL ratio, along with a tendency of decreased stomach and intestine MEL in fed snakes compared to fasting ones. BKA was not affected by feeding. Overall, we found that feeding modulates metabolic rates, CORT levels, and immune cell distribution in boas. Increased baseline CORT may be important to mobilize energy to support the metabolic increment during the postprandial period. Increased HL ratio might be an immunoregulatory effect of increased CORT, which has been shown in different physiological situations such as in response to immune challenge. Our results suggest that feeding activates the hypothalamic-pituitary-adrenal axis and modulates immune cell redistribution, possibly contributing to fighting potential injuries and infections derived from predation and from pathogens present in ingested food.

Dietary Fatty Acids in Postprandial Triglyceride-Rich Lipoproteins Modulate Human Monocyte-Derived Dendritic Cell Maturation and Activation.

Dietary fatty acids have been demonstrated to modulate systemic inflammation and induce the postprandial inflammatory response of circulating immune cells. We hypothesized that postprandial triglyceride-rich lipoproteins (TRLs) may have acute effects on immunometabolic homeostasis by modulating dendritic cells (DCs), sentinels of the immunity that link innate and adaptive immune systems. In healthy volunteers, saturated fatty acid (SFA)-enriched meal raised serum levels of granulocyte/macrophage colony-stimulating factor GM-CSF (SFAs > monounsaturated fatty acids (MUFAs) = polyunsaturated fatty acids (PUFAs)) in the postprandial period. Autologous TRL-SFAs upregulated the gene expression of DC maturation (CD123 and CCR7) and DC pro-inflammatory activation (CD80 and CD86) genes while downregulating tolerogenic genes (PD-L1 and PD-L2) in human monocyte-derived DCs (moDCs). These effects were reversed with oleic acid-enriched TRLs. Moreover, postprandial SFAs raised IL-12p70 levels, while TRL-MUFAs and TRL-PUFAs increased IL-10 levels in serum of healthy volunteers and in the medium of TRL-treated moDCs. In conclusion, postprandial TRLs are metabolic entities with DC-related tolerogenic activity, and this function is linked to the type of dietary fat in the meal. This study shows that the intake of meals enriched in MUFAs from olive oil, when compared with meals enriched in SFAs, prevents the postprandial production and priming of circulating pro-inflammatory DCs, and promotes tolerogenic response in healthy subjects. However, functional assays with moDCs generated in the presence of different fatty acids and T cells could increase the knowledge of postprandial TRLs' effects on DC differentiation and function.

The Combination of Whey Protein and Dietary Fiber Does Not Alter Low-Grade Inflammation or Adipose Tissue Gene Expression in Adults with Abdominal Obesity.

BACKGROUND: Abdominal obesity is characterized by low-grade inflammation and plays a central role in the development of type 2 diabetes and cardiovascular diseases. Dietary factors can influence low-grade inflammation and affect adipose tissue function. AIM: To investigate the separate and combined effects of whey protein and cereal fiber on inflammatory markers and adipose tissue gene expression in abdominal obesity. METHODS: We performed a 12-week, double-blind, randomized controlled dietary intervention in 65 adults with abdominal obesity. The participants were randomized to 4 groups using a 2 × 2 factorial design; they received either 60 g/day of whey protein or maltodextrin in combination with high-fiber wheat bran products (30 g fiber/day) or low-fiber refined wheat products (10 g fiber/day). Plasma concentrations of tumor necrosis factor α (TNF-α), high-sensitivity C-reactive protein (hs-CRP), monocyte chemoattractant protein-1 (MCP-1), interleukin 1 receptor antagonist (IL-1Ra), and adiponectin were measured before and after intervention. Changes in gene expression related to inflammation, insulin signaling, and lipid metabolism were measured in abdominal subcutaneous adipose tissue. RESULTS: After intervention, TNF-α was reduced for both high-fiber groups compared with baseline, but did not significantly differ from the low-fiber groups. There were no differences in fasting or postprandial inflammatory markers between the groups. The relative gene expression of ribosomal protein S6 kinase B1 (S6K1) was increased after whey protein compared with maltodextrin consumption. CONCLUSION: Intake of whey protein in combination with high cereal fiber content did not differentially affect low-grade inflammation or adipose tissue gene expression compared with maltodextrin and low fiber content in individuals with abdominal obesity.

Effect of Dietary Lipids on Endotoxemia Influences Postprandial Inflammatory Response.

Metabolic syndrome (MetS) results in postprandial metabolic alterations that predisposes one to a state of chronic low-grade inflammation and increased oxidative stress. We aimed to assess the effect of the consumption of the quantity and quality of dietary fat on fasting and postprandial plasma lipopolysaccharides (LPS). A subgroup of 75 subjects with metabolic syndrome was randomized to receive 1 of 4 diets: HSFA, rich in saturated fat; HMUFA, rich in monounsaturated fat; LFHCC n-3, low-fat, rich in complex carbohydrate diet supplemented with n-3 polyunsaturated fatty acids; LFHCC low-fat, rich in complex carbohydrate diet supplemented with placebo, for 12 weeks each. We administered a fat challenge reflecting the fatty acid composition of the diets at postintervention. We determined the plasma lipoproteins and glucose and gene expression in peripheral blood mononuclear cells (PBMC) and adipose tissue. LPS and LPS binding protein (LBP) plasma levels were determined by ELISA, at fasting and postprandial (4 h after a fat challenge) states. We observed a postprandial increase in LPS levels after the intake of the HSFA meal, whereas we did not find any postprandial changes after the intake of the other three diets. Moreover, we found a positive relationship between the LPS plasma levels and the gene expression of IkBa and MIF1 in PBMC. No statistically significant differences in the LBP plasma levels at fasting or postprandial states were observed. Our results suggest that the consumption of HSFA diet increases the intestinal absorption of LPS which, in turn, increases postprandial endotoxemia levels and the postprandial inflammatory response.

Antiinflammatory and ROS Suppressive Effects of the Addition of Fiber to a High-Fat High-Calorie Meal.

Background: Fiber intake is associated with a reduction in the occurrence of cardiovascular events and diabetes. Objective: To investigate whether the addition of fiber to a high-fat, high-calorie (HFHC) meal prevents proinflammatory changes induced by the HFHC meal. Design: Ten normal fasting subjects consumed an HFHC meal with or without an additional 30 g of insoluble dietary fiber on 2 separate visits. Blood samples were collected over 5 hours, and mononuclear cells (MNCs) were isolated. Results: Fiber addition to the HFHC meal significantly lowered glucose excursion in the first 90 minutes and increased insulin and C-peptide secretion throughout the 5-hour follow-up period compared with the meal alone. The HFHC meal induced increases in lipopolysaccharide (LPS) concentrations, MNC reactive oxygen species generation, and the expression of interleukin (IL)-1ß, tumor necrosis factor α (TNF-α), Toll-like receptor (TLR)-4, and CD14. The addition of fiber prevented an increase in LPS and significantly reduced the increases in ROS generation and the expression of IL-1ß, TNF-α, TLR-4, and CD14. In addition, the meal increased Suppressor of cytokine signaling (SOCS)-3 and protein tyrosine phosphatase 1B (PTP-1B) messenger RNA and protein levels, which were inhibited when fiber was added. Conclusions: The addition of fiber to a proinflammatory HFHC meal had beneficial anti-inflammatory and metabolic effects. Thus, the fiber content of the American Heart Association meal may contribute to its noninflammatory nature. If these actions of dietary fiber are sustained following long-term intake, they may contribute to fiber's known benefits in the prevention of insulin resistance, type 2 diabetes, and atherosclerosis.

The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides.

Salivary immunoglobulin A (IgA) serves as a major effector in mucosal immunity by preventing submucosal invasion of pathogens. However, the mechanism by which consumption of fermentable fibers increases IgA in saliva was not fully elucidated. This study investigated the effects of fructooligosaccharides (FOS) intake and time after feeding on IgA levels in the saliva and cecal digesta and on the concentration of short-chain fatty acids (SCFA) in the cecum in rats. Five-week-old rats were fed a fiber-free diet or a diet with 50 g/kg FOS for zero, one, four, and eight weeks. Ingestion of FOS at one and eight weeks led to a higher IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.05), which positively correlated with the concentration of SCFA in the cecal digesta (rs = 0.86, p = 0.0006, n = 12), but showed no correlation with the concentration of IgA in the cecal digesta (rs = 0.15, p = 0.3, n = 48). These results suggested that ingestion of FOS increased salivary IgA secretion through high levels of SCFA in the large intestine, which was produced by fermentation of FOS. Thus, continuously ingesting FOS for more than one week could increase secretion of salivary IgA.

Postprandial dietary fatty acids exert divergent inflammatory responses in retinal-pigmented epithelium cells.

Postprandial triglyceride-rich lipoproteins (TRLs) lead to a complex series of events that are potentially oxidative and inflammatory. The main goal of this study was to characterize the influence of postprandial TRLs with different fatty acid compositions (mainly SFAs, MUFAs or MUFAs plus omega-3 PUFAs) on oxidative and inflammatory markers in RPE cells, which play a pivotal role in age-related macular degeneration (AMD). Compared to TRL-SFAs, TRL-MUFAs and TRL-MUFAs plus omega-3 PUFAs decreased the production of ROS and nitrite, and the gene expression and secretion of IL-1ß, IL-6, TNF-α, IFNγ and VEGF. For the first time we show that postprandial TRLs are metabolic entities able to induce RPE oxidative stress and inflammation in a fatty acid-dependent manner, TRL-SFAs ⋙ TRL-MUFAs = TRL-MUFAs plus omega-3 PUFAs. These exciting findings open new opportunities for developing novel nutritional strategies with olive oil as the principal dietary source of oleic acid to prevent the development and progression of AMD.

High-fat meals induce systemic cytokine release without evidence of endotoxemia-mediated cytokine production from circulating monocytes or myeloid dendritic cells.

AIMS: Dietary fats have been shown to promote the translocation of bacterial endotoxins from the gut into circulation, which may induce systemic inflammation and modulate the inflammatory response of circulating immune cells. The aim of this study was to determine the effect of the postprandial milieu on inflammation and the inflammatory response of antigen presenting cells in the context of type 1 diabetes (T1D). MATERIALS AND METHODS: Eleven patients with T1D and eleven nondiabetic controls were recruited as part of the FinnDiane study and given two fatty meals during 1 day. Cytokine responses in monocytes and myeloid dendritic cells (mDCs) as well as serum lipopolysaccharide activity levels, triglyceride concentrations and cytokine concentrations were measured from fasting and postprandial blood samples. RESULTS: Postprandially, patients with T1D and controls showed significant increases in eight inflammatory cytokines (IL-6, TNF-α, IL-1ß, IFN-α, IL-10, IFN-γ, IL-12 and MIP-1ß) without concomitant increase in serum LPS activity. Serum cytokine production was similar in both groups. No postprandial change was seen in the IL-6, TNF-α or IL-1ß production of mDCs or monocytes. At fasting, diabetic mDCs exhibited higher LPS-induced IL-6 and IL-1ß production than controls. CONCLUSIONS: Acute high-fat meals increase circulating cytokines but have no effect on serum lipopolysaccharide activity levels or cytokine production in circulating mDCs or monocytes. Our results suggest that postprandial increase in serum cytokine levels is neither mediated by circulating endotoxins nor the activation of circulating innate cells. The production of high-fat meal-induced inflammatory markers is most likely regulated at the tissue level.

Postprandial cell inflammatory response to a standardised fatty meal in subjects at different degree of cardiovascular risk.

A fatty meal may represent a challenge of in vivo acute inflammatory reaction. We evaluated the acute effects of a standardised fatty meal administration on leukocytes and platelets and on their interactions on 61 subjects at different degree of cardiovascular risk, without any clinical event. Before and 2 hours after a fatty meal, blood cells were counted and markers of leukocyte (intracellular myeloperoxidase [MPO] and Mac-1) and platelet (P-selectin and microparticles) activation and mixed platelet-leukocyte conjugates measured by flow-cytometry. After the fatty meal, both white blood cell and platelet count significantly increased, more markedly in subjects with lower cardiovascular risk score. Mac-1 expression too increased (from 32.2 ± 27.2% to 45.6 ± 29.0%, p=0.0016), while MPO decreased (from 83.1 ± 16.3% to 64.5 ± 23.1%, p<0.0001). A trend for increased platelet activation and interaction with leukocytes was also observed. Women were more markedly susceptible to fatty meal challenge, as compared to men, while age did not seem to affect any cell response to fatty meal. Waist-to-hip ratio and body mass index influenced polymorphonuclear cells (PMN) degranulation and platelet count increase, respectively. Cellular responses to the fatty meal, in particular PMN degranulation, were attenuated in subjects at higher degree of cardiovascular risk, who showed a basal mild inflammatory activation status. In conclusion, a fatty meal consumption may represent a model of acute inflammatory response and appears to be modulated by different demographic and cardiovascular risk degree. This model could be applied to study the effect of food-derived antioxidants or nutritional supplements, but its relevance remains to be demonstrated.

Differential effects of cream, glucose, and orange juice on inflammation, endotoxin, and the expression of Toll-like receptor-4 and suppressor of cytokine signaling-3.

OBJECTIVE: We have recently shown that a high-fat high-carbohydrate (HFHC) meal induces an increase in plasma concentrations of endotoxin (lipopolysaccharide [LPS]) and the expression of Toll-like receptor-4 (TLR-4) and suppresser of cytokine signaling-3 (SOCS3) in mononuclear cells (MNCs) in addition to oxidative stress and cellular inflammation. Saturated fat and carbohydrates, components of the HFHC meal, known to induce oxidative stress and inflammation, also induce an increase in LPS, TLR-4, and SOCS3. RESEARCH DESIGN AND METHODS: Fasting normal subjects were given 300-calorie drinks of either glucose, saturated fat as cream, orange juice, or only water to ingest. Blood samples were obtained at 0, 1, 3, and 5 h for analysis. RESULTS: Indexes of inflammation including nuclear factor-kappaB (NF-kappaB) binding, and the expression of SOCS3, tumor necrosis factor-alpha (TNF-alpha), and interleukin (IL)-1beta in MNCs, increased significantly after glucose and cream intake, but TLR-4 expression and plasma LPS concentrations increased only after cream intake. The intake of orange juice or water did not induce any change in any of the indexes measured. CONCLUSIONS: Although both glucose and cream induce NF-kappaB binding and an increase in the expression of SOCS3, TNF-alpha, and IL-1beta in MNCs, only cream caused an increase in LPS concentration and TLR-4 expression. Equicaloric amounts of orange juice or water did not induce a change in any of these indexes. These changes are relevant to the pathogenesis of atherosclerosis and insulin resistance.

Patients with insulin-dependent diabetes or coronary heart disease following rehabilitation express serum fractalkine levels similar to those in healthy control subjects.

The chemokine and adhesion molecule fractalkine and its receptor CX(3)CR1 have emerged as interesting regulators in inflammation and related atherosclerosis. The pro-inflammatory status may be counteracted by appropriate treatment, such as in rehabilitation. We compared serum fractalkine concentrations of 46 patients with coronary heart disease (CHD) and 47 insulin-dependent diabetic patients (IDDM) following rehabilitation with those of 50 control subjects. Following rehabilitation serum fractalkine levels (477 + or - 225 pg/mL) in CHD patients were similar to those in control subjects (572 + or - 205 pg/mL; P = 0.303), whereas fractalkine levels were lower in IDDM patients (430 + or - 256 pg/mL; P = 0.042). No significant difference between CHD and IDDM patients was present (P = 0.319). Postprandial hyperlipemia may influence inflammation; thus, we investigated fractalkine levels four and eight hours after inducing postprandial hyperlipemia. However, we did not find any significant alterations in CHD and diabetic patients, whereas the fractalkine levels in controls were reduced. In vitro, lipofundin used as a hyperlipemic stimulus was added to vessel wall cells and reduced fractalkine levels. Low fractalkine levels in patients attending rehabilitation indicate a beneficial effect of the rehabilitation procedure on innate inflammatory pathways, such as the chemokine and adhesion molecule fractalkine.

Leukocyte activation by triglyceride-rich lipoproteins.

OBJECTIVE: Postprandial lipemia has been linked to atherosclerosis and inflammation. Because leukocyte activation is obligatory for atherogenesis, leukocyte activation by triglyceride-rich lipoproteins (TRLs) was investigated. METHODS AND RESULTS: The expression of CD11b and CD66b after incubation with glucose and native and artificial TRLs (NTRL and ATRL) in vivo and in vitro was evaluated by flowcytometry. Oral fat loading tests showed an increased expression of CD11b on monocytes and neutrophils and CD66b on neutrophils. In 11 volunteers, postprandial leukocytes became enriched with meal-derived fatty acids ([1-(13)C]16:0) suggesting uptake of exogenous fat. ApoB binding on leukocytes measured by flowcytometry in 65 subjects was highest on neutrophils and monocytes suggesting adherence of apoB-containing lipoproteins. Physiological concentrations of TRLs showed 62% increased neutrophil CD11b and a dose-dependent increased monocyte CD11b up to 84% in vitro. Incubations with lipid emulsions in the hypertriglyceridemic range showed a 5-fold increased monocyte CD11b expression, which was higher than the positive control (fMLP), and a dose-dependent 2- to 3-fold increased neutrophil CD11b and CD66b. The oxidative scavenger DMTU decreased the neutrophil CD66b expression by 36%. CONCLUSIONS: Acute hypertriglyceridemia is a leukocyte activator most likely by direct interaction between TRLs and leukocytes and uptake of fatty acids. TG-mediated leukocyte activation is an alternative proinflammatory and proatherogenic mechanism of hypertriglyceridemia in part associated to the generation of oxidative stress.

Induction of postprandial inflammatory response in adult onset growth hormone deficiency is related to plasma remnant-like particle-cholesterol concentration.

Increased cardiovascular mortality due to premature atherosclerosis is a clinical feature in the adult-onset GH deficiency (AGHD) syndrome. Inflammation is a key feature in atherogenesis and may be triggered by postprandial lipoprotein remnants. We hypothesized that increased postprandial lipoprotein remnant levels in AGHD may be associated with an inflammatory response. In this case-control study, 10 AGHD patients [6 males and 4 females; age, 48 +/- 9 yr; body mass index (BMI), 26.9 +/- 2.6 kg/m(2)] and 10 healthy control subjects (matched for age, BMI, gender, baseline lipid levels, and apolipoprotein E genotype) were included. They all ingested an oral fat load. Fasting and postprandial levels of plasma remnant-like particle-cholesterol (RLP-C; 0.31 +/- 0.13 mmol/liter and 4.14 +/- 1.37 mmol/liter.h in GHD; 0.18 +/- 0.06 mmol/liter and 2.56 +/- 1.02 mmol/liter.h in controls, respectively) were significantly increased in AGHD patients compared with control subjects. The median inflammatory cytokines, IL-6 and TNF-alpha, were higher in the fasting [3.9 (range, 3.1-11.9) pg/ml and 6.8 (range, 2.5-27.6) pg/ml, respectively] and postprandial [151.7 (range, 87.0-294.3) pg/ml.24 h and 289.9 (range, 87.5-617.6) pg/ml.24 h, respectively] states in AGHD than in controls [fasting, 0.9 (range, 0.2-5.2) pg/ml and 2.8 (range, 2.5-5.7) pg/ml; and postprandial, 54.5 (range, 11.50-126.5) pg/ml.24 h and 118.3 (range, 81.2-243.1) pg/ml.24 h, respectively]. In addition, postprandial profile of RLP-C and IL-6 in AGHD and in the total group were significantly associated (r(2) = 0.44, P < 0.05; and r(2) = 0.38, P < 0.01, respectively). In conclusion, the increased postprandial RLP-C level in GHD is associated with an inflammatory response that may result in increased susceptibility for premature atherosclerosis.

Eosinophil-derived proteins in postprandial (food-dependent) exercise-induced anaphylaxis.

BACKGROUND: Postprandial exercise-induced anaphylaxis (PPEIAn) is a form of EIAn in which the ingestion of food before the exercise is associated with the onset of symptoms. Skin reactivity and the presence of specific serum IgE to several food allergens suggest the occurrence of food-dependent allergic mechanisms. METHODS: In order to study the involvement of eosinophils in the pathogenesis of PPEIAn we measured the changes in serum eosinophil cationic protein (ECP) and eosinophil protein X/eosinophil-derived neurotoxin (EPX/EDN) levels in 6 patients with PPEIAn, subjected to three separate challenges with either suspected foods only, exercise after a meal without or with suspected food ingestion. RESULTS: We found serum levels of both eosinophil-derived proteins increased only in challenges including both exercise and suspected food ingestion. Symptoms of anaphylaxis occurred in 3 of these patients. CONCLUSIONS: The increased release of eosinophil basic proteins in PPEIAn patients, caused by physical exercise following ingestion of suspected foods, is not obligatory for the definition of the syndrome.