TUB gene expression in hypothalamus and adipose tissue and its association with obesity in humans.

BACKGROUND/OBJECTIVES: Mutations in the Tubby gene (TUB) cause late-onset obesity and insulin resistance in mice and syndromic obesity in humans. Although TUB gene function has not yet been fully elucidated, studies in rodents indicate that TUB is involved in the hypothalamic pathways regulating food intake and adiposity. Aside from the function in central nervous system, TUB has also been implicated in energy metabolism in adipose tissue in rodents. We aimed to determine the expression and distribution patterns of TUB in man as well as its potential association with obesity. SUBJECTS/METHODS: In situ hybridization was used to localize the hypothalamic regions and cells expressing TUB mRNA. Using RT-PCR, we determined the mRNA expression level of the two TUB gene alternative splicing isoforms, the short and the long transcript variants, in the hypothalami of 12 obese and 12 normal-weight subjects, and in biopsies from visceral (VAT) and subcutaneous (SAT) adipose tissues from 53 severely obese and 24 non-obese control subjects, and correlated TUB expression with parameters of obesity and metabolic health. RESULTS: Expression of both TUB transcripts was detected in the hypothalamus, whereas only the short TUB isoform was found in both VAT and SAT. TUB mRNA was detected in several hypothalamic regions involved in body weight regulation, including the nucleus basalis of Meynert and the paraventricular, supraoptic and tuberomammillary nuclei. We found no difference in the hypothalamic TUB expression between obese and control groups, whereas the level of TUB mRNA was significantly lower in adipose tissue of obese subjects as compared to controls. Also, TUB expression was negatively correlated with indices of body weight and obesity in a fat-depot-specific manner. CONCLUSIONS: Our results indicate high expression of TUB in the hypothalamus, especially in areas involved in body weight regulation, and the correlation between TUB expression in adipose tissue and obesity. These findings suggest a role for TUB in human obesity.

Chenodeoxycholic acid reduces intestinal permeability in newly weaned piglets.

Piglets are highly susceptible to gut health-related problems. Intravenously administered chenodeoxycholic acid (CDCA) affects gut health mediated through glucagon-like peptide 2 (GLP-2). To test whether CDCA is a suitable feed additive for improving gut health, a trial was performed with newly weaned (21 d) piglets offered a diet with or without 60 mg CDCA/kg feed (n = 24/treatment). Upon weaning, piglets were fasted for 16 h and then intragastrically dosed with 20 g test feed in 40 g water. Subsequently, a jugular blood sample was taken on 45, 90, 135, or 180 min for analysis of GLP-2, peptide YY (PYY), and glucose. Afterwards, piglets were offered the experimental diets ad libitum. On days 3.5, 7.5, and 10.5 after weaning, serum responses to an intragastric dose of lactulose and Co-EDTA were tested at 2 h after dosing in 8 piglets per treatment. Immediately thereafter, piglets were euthanized, intestines were harvested, and permeability was measured ex vivo using the everted gut sac technique with 4 kDa fluorescein isothiocyanato (FITC)-dextran as marker at 25, 50, and 75% of the length of the small intestine. Dietary CDCA did not affect (P > 0.05) ADFI, ADG, G:F, blood glucose, and plasma GLP-2 and PYY. Serum cobalt and lactulose at day 10.5 tended to be lower in CDCA pigs compared with control pigs. Serum cobalt and lactulose concentrations were positively correlated (r = 0.67; P < 0.01). In conclusion, CDCA tended to reduce intestinal permeability at 10.5 d after weaning when fed to newly weaned piglets, implying that CDCA deserves further study as a means for improving intestinal health. The positive correlation found between Co-EDTA and lactulose indicates that both marker molecules measure similar change in permeability.

Effect of IGF-rich colostrum on bowel adaptation in neonatal piglets with short bowel syndrome.

BACKGROUND: Insulin-like growth factor 1 (IGF-1), a polypeptide growth factor with mitogenic effects on intestinal epithelial crypt cells occurs naturally in high concentrations in colostrum. The hypothesis for this study was that colostrum rich in IGF-1 could promote small bowel adaptation in neonatal piglets with short bowel syndrome. METHODS: Twenty-four piglets, aged 7 days, underwent 75% small bowel resection and were fed 525 kJ x kg(-1) x d(-1) (125 kcal) of colostrum-based formula (Rs(+)) or placebo formula (Rs(-)). Immunoglobulin G (IgG) accounted for 35% of the protein and was compensated with casein and whey protein in the control feed. The piglets were weighed daily and killed 28 days after surgery. Bowel samples were taken at surgery and at death. RESULTS: Relative body-weight increase did not differ between the Rs(+) and Rs(-) group (84% +/- 9% vs. 90% +/- 12%, P = 0.83). There was a significant relative increase in crypt depth in the Rs - compared with the Rs + group (201% +/- 15% vs. 147% +/- 17%, P = 0.02) and total protein (mg/cm bowel) (482 +/- 51 vs. 278 +/- 46, P = 0.008). Increase in villus length, DNA/RNA content, and mitotic index did not differ between groups. CONCLUSION: Colostrum supplement rich in IGF-1 has no benefits over protein-enriched feed with respect to growth and bowel adaptation in neonatal piglets with short bowel syndrome.

Characterization of nonresponse to high caloric oral nutritional therapy in depleted patients with chronic obstructive pulmonary disease.

Nutritional support can increase body weight and physiologic function in COPD, but there are some patients who do not respond to nutritional therapy. The aim of this prospective study was to describe the nonresponse to 8 wk of oral nutritional supplementation therapy (500 to 750 kcal/d extra), implemented in an inpatient pulmonary rehabilitation program, with respect to lung function, body composition, energy balance, and systemic inflammatory profile in 24 (16 male) depleted patients with COPD. On the basis of the weight change after 8 wk, patients were divided into three groups (Group 1: weight gain < 2% of baseline body weight, n = 5; Group 2: weight gain 2 to 5%, n = 9; Group 3: weight gain >/= 5%, n = 10). Although no differences were seen in lung function and body composition, Group 1 was characterized by older age, a lower baseline dietary intake/resting energy expenditure (REE) ratio, and a greater number of users of continuous supplemental oxygen when compared with Group 3. In addition, Group 1 exhibited higher baseline concentrations of fasting glucose and LPS-binding protein than did Groups 2 and 3. The concentrations of the soluble TNF- receptors 55 and 75 were elevated in Groups 1 and 2 when compared with Group 3. Furthermore, a significant, inverse correlation coefficient between baseline dietary intake and soluble intercellular adhesion molecule was revealed (r = -0.50, p = 0.016). On linear regression analysis, age, baseline intake/REE ratio, sTNF-receptor 55, and extracellular/intracellular water (ECW/ICW) ratio were selected as independent, significant parameters contributing to a total explained variation of 78% in weight change after nutritional therapy. In conclusion, nonresponse to nutritional therapy in COPD is associated with ageing, relative anorexia, and an elevated systemic inflammatory response. Further research is needed to investigate whether these factors contribute to eventual disturbances in intermediary metabolism as reflected by the increased glucose concentration and ECW/ICW ratio.

Glutamine and intestinal immune cells in humans.

BACKGROUND: Total parenteral nutrition (TPN) is associated with depletion of intestinal immune cells and increased gut permeability (GP). Adding glutamine (GLN) to TPN preserves GP by an unknown mechanism. Intestinal immune cells situated between the enterocytes (intraepithelial lymphocytes, [IEL]) influence GP in vitro. To obtain insight into the underlying mechanism of GLN on GP, we investigated the effects of GLN-supplemented TPN on IEL, immunoglobulin A (IgA) plasma cells and goblet cells, and enterocyte proliferation in intestinal biopsies. METHODS: Twenty patients randomly received GLN-enriched TPN (GT) or isonitrogenous standard TPN (ST). Proliferation and number of immune cells were measured in intestinal biopsies obtained before and after 10 days of TPN. RESULTS: No change in proliferative activity or in number of IgA plasma cells was observed. Goblet cells increased in the ST group, whereas the change seen in the GT group did not reach significance. In the GT group, IEL decreased, whereas in the ST group, no change in the number of IEL was observed. CONCLUSIONS: TPN was not associated with changes in proliferative activity or with depletion of gut immune cells. The data indicate that GLN-supplemented TPN has a different effect on intestinal immune cells compared with standard TPN.

Dietary n-3 fatty acids increase spleen size and postendotoxin circulating TNF in mice; role of macrophages, macrophage precursors, and colony-stimulating factor-1.

In experimental studies in mice, dietary supplementation with n-3 fatty acids (FA) alleviates inflammation and increases resistance to infection. Nevertheless, TNF production capacity was found to be increased in n-3 FA-fed mice. We previously found increased relative spleen weights in n-3 FA-fed mice. In this study, the nature of this increased spleen size was further investigated. Spleen cellularity was increased significantly in mice fed n-3 FA (fish oil 15% w/w), compared with controls fed corn oil (15%) or normal lab chow (p < 0.05). Experiments with T cell-deficient nude mice and experiments using macrophage depletion through liposomal dichloromethylene-biphosphonate revealed that the increase in spleen cellularity is T cell independent and largely due to macrophage accumulation in the spleen. Accumulation of marginal zone and red pulp macrophages was histologically and immunohistochemically confirmed. n-3 FA induced peripheral blood monocytosis and an aspecific increase in bone marrow cellularity. Postendotoxin circulating TNF concentrations were increased significantly in n-3 FA-fed mice compared with controls. Splenectomy did not abolish this increase in circulating TNF. However, after macrophage depletion through liposomal dichloromethylene-biphosphonate, circulating TNF was not detectable after endotoxin challenge. Circulating concentrations of CSF-1 did not differ between the various experimental groups. It is suggested that the cellular changes observed relate to increased constitutive production of TNF.

Fish oil increases the release of tumour necrosis factor and interleukin-6, and has no effect on the incidence of multiple organ failure in rats with peritonitis.

OBJECTIVE: To find out if fish oil given intraperitoneally would cause a reduction in the release of tumour necrosis factor and interleukin-6 in abdominal exudate and blood (experiment A), and if it reduces the incidence of organ failure in rats with peritonitis (experiment B). DESIGN: Laboratory experiment. SETTING: University animal laboratory. MATERIAL: Thirty-six selectively decontaminated rats in each experiment. INTERVENTIONS: All rats were pretreated with 2 ml fish oil, lecithin, or saline, intraperitoneally for one or six weeks before intraperitoneal injection of zymosan. Experiment A: Samples of abdominal exudate and plasma were taken regularly for 24 hours after the zymosan had been given. Experiment B: Clinical, biochemical, and histological variables were measured over a 12-day period after the zymosan had been given. MAIN OUTCOME MEASURES: Experiment A: Concentrations of tumour necrosis factor and interleukin-6 in abdominal exudate and plasma. Experiment B: Incidence of multiple organ failure. RESULTS: Experiment A: Concentrations of tumour necrosis factor and interleukin-6 in abdominal exudate and plasma were significantly higher in rats pretreated with fish oil, compared with control rats. This effect was more pronounced after six weeks of pretreatment. Experiment B: There were no significant differences between the groups for any variable. CONCLUSION: Fish oil given intraperitoneally increased rather than reduced local and systemic release of tumour necrosis factor and interleukin-6, and did not reduce the incidence of organ failure in rats with sterile peritonitis.

The effect of replacement of dietary fat by palm oil on in vitro cytokine release.

In the present study the effect of replacement of dietary fat by palm oil in the normal Western diet on the in vitro release of the inflammatory cytokines tumour necrosis factor (TNF), interleukin (IL)-6 and IL-8 was examined. A maximal replacement of 700 g/kg dietary fat was achieved for thirty-eight male volunteers who consumed either a palm-oil diet or a control diet in a double-blind, cross-over study with 6-week experimental periods, and 3-week run-in and wash-out periods. At the end of both experimental periods, whole blood was stimulated in vitro with 0.02 (sub-optimal), or 10 ng lipopolysaccharide (LPS)/ml (maximal), whereafter TNF, IL-6, and IL-8 concentrations in the culture supernatant fraction were measured using specific enzyme-linked immunosorbent assays (ELISA). Mean cytokine production with sub-optimal, or maximal LPS stimulation of peripheral whole blood was similar for both the palm oil, and the control group. The relative TNF response, however, was reduced by replacement of dietary fat with palm oil. Separate analysis of the data from the first and second experimental periods strongly suggested that the residual effect of the palm-oil diet on the relative TNF response was longer than 9 weeks. Cytokine homeostasis determines the course of the inflammatory response and the progression of atherosclerosis. The effect of palm-oil consumption on the proneness of the peripheral blood cells to produce TNF may, therefore, alter the prevalence of these common diseases.

Dietary fish-oil supplementation in experimental gram-negative infection and in cerebral malaria in mice.

Dietary fish-oil supplementation interferes with eicosanoid production and appears to decrease production of interleukin-1 (IL-1) and tumor necrosis factor (TNF). The effect of fish oil was investigated in an intramuscular Klebsiella pneumoniae infection in Swiss mice and in cerebral malaria induced by Plasmodium berghei in C57B1/6 mice. After a low inoculum of K. pneumoniae, 90% of fish oil-fed mice survived; survival in control mice fed equal amounts of corn or palm oil or normal chow was 30%, 40%, and 0, respectively. Cerebral malaria occurred in only 23% of fish oil-fed mice; in the controls, cerebral malaria developed in 61%, 81%, and 78%, respectively. Contrary to what was expected, lipopolysaccharide-induced ex vivo production of IL-1 alpha and TNF alpha by peritoneal cells was significantly enhanced in fish oil-fed mice compared with controls. Indomethacin treatment did not alter the outcome in these two infections, thus arguing against reduced prostaglandin synthesis as an explanation for the increase in resistance to infection.