Articles 1-10

Nutrition and immune function in the aged: clinical implications and molecular mechanisms

Simin Nikbin Meydani, D.V.M., Ph.D. USDA/HNRC at Tufts

University, Boston, Massachusetts, USA.

The influence of nutrition on immune function has been recognized since the 1800’s. The incidence of neoplastic and infectious diseases is increased in the aged, as is the resulting morbidity and mortality. The well-documented age-associated dysregulation of immune function is an important contributor to the increased incidence of mortality from these diseases. The underlying mechanisms for this age-associated immune dysregulation is not well understood; however, since marginal deficiency of several nutrients is prevalent in the aged, and because nutrients play a key role in regulation of the immune response, these deteriorations have been partly attributed to the poor nutritional status of the aged. In the last twenty years, we have investigated the role of nutrients in age-associated dysregulation of the immune function, developed strategies to reverse/reduce these changes and their clinical manifestations, and elucidated some of the cellular and molecular mechanisms involved in these interactions. The results from these studies and their implications for maintaining optimal nutrient intake and health status of the aged will be discussed.

Nutrition and immunity: a key focus in production and health

Korinn E. Saker 1

1 VA-MD Regional College of Veterinary Medicine and 2 Department of Dairy Science, Virginia Tech, Blacksburg, VA

Prevention and treatment of disease are primary concerns of those involved in the production of domestic food animals and the maintenance of companion animals. Maintaining an abundant supply of food and animal products is vital to both human and animal well-being from the perspective of both consumers and producers. There are many potential causes for immunosuppression including inadequate nutrition. The relationship between specific nutrients such as protein, fatty acids, vitamin E, selenium, copper and zinc have been well-documented in altering growth, feed efficiency, reproduction, stress response to handling and disease challenge, carcass and milk quality and yield, drug usage, and environmental contamination. Many areas across the world have marginal or deficient nutrient stores in soils and plants, making optimal animal production and health a challenge. Over the years, studies have elucidated the physiological demands that production and disease place on nutrient utilization, and identified various cellular and molecular mechanisms involved in these interactions. Work in these areas continues to advance our knowledge base and develop creative methods of improving animal health and production through nutrition. A summary of specific nutrient-related immune challenge studies in food and companion animals will be discussed.

The effect of sprouted barley-corn with antioxidant properties on the humoral immune response of turkey poults

E. Carlin 1 , Ch. Iben 1 , E. Wagner 1 , C. Neubauer 2

Institute of Nutrition 1 , University of Veterinary Medicine, Vienna
Clinic for Poultry and Pet Birds 2 , University of Veterinary Medicine, Vienna

Objectives: The aim of this study was to evaluate the acceptance of a growing and fattening feed for turkeys containing 28 % of starch of sprouted barley-corn only and a diet containing 28 % of starch of sprouted barley-corn and 10 % bruised barley-sprouts with antioxidant properties (tocopherol 9.93 mg/kg; tocotrienol 41.27 mg/kg) and their effect on the humoral immune response of turkey poults. Methods: Two experiments were conducted in the current study. Three groups of 19 one-day-old male poults were placed each in a floor-pen in experiment 1. The first feeding-phase lasted until the end of week 3 and the second phase until the end of the trial (week 8). Group 1 was fed commercial turkey feed as a control diet, group 2 was fed a diet containing 28 % of starch of sprouted barley-corn and group 3 was fed a diet containing 28 % of starch of sprouted barley-corn and 10 % bruised barley-sprouts, (additional feed-ingredients: extracted soybean meal, minerals, vitamin and traceelement supplementation, rapeseed oil, wheat, corn, methionin, lysin). The poults were vaccinated against Newcastle disease virus (NDV) at the age of two weeks. Anti-NDV antibody titers were measured on the day of vaccination, on day 35 and at the end of the trial, on day 56. In the second experiment two groups of 19 one-day-old female poults were placed each in a floor-pen. Group 1 was fed commercial turkey feed as a control diet and group 2 was fed a diet containing 10 % bruised barley-sprouts. Housing, feeding and vaccination against Newcastle disease virus and measurements of anti-NDV antibody titers were arranged as in experiment 1. Statistical evaluation All variables were evaluated using the Kolmogorov-Smirnov method in order to assess their normal distribution. The statistical evaluation of the body weight gains was performed using analysis of variance. The anti-NDV antibody titers were compared using the Mann-Whithney-U- Test. Results: Feed intake, body weight gains and feed conversion (kg feed/kg weight gain) were in the normal range in both experiments, (average body weight gains of male turkeys in experiment 1: 4050.53 g, SD 496.06 g; average body weight gains of female turkeys in experiment 2: 3203.95 g, SD 411.2 g). The acceptance of sprouted barley-corn and starch of sprouted barley-corn and its use as fattening feed was shown by the results of feed consumption and feed conversion. In experiment 1 anti-NDV antibody titers of poults fed the diet containing sprouted barley seemed to show a better antibody response than poults fed the control diet and experiment 2 showed a significant difference between both groups. Conclusion: Diets containing 28 % of starch of sprouted barley-corn and 10 % bruised barley-sprouts can be used as feed. The fattening yield was in the normal range in both experiments. In both experiments no significant difference in fattening yield and feed conversion could be observed. In experiment 1 the immune response in group 3 (starch and bruised barley-sprouts) was significantly higher on day 35 and no antibody response could be observed in group 2 (starch) on day 56. In experiment 2 the anti-NDV antibody-titers were significantly higher in group 1 (control diet) on day 14, equal in both groups on day 35 and significantly higher in group 2 (bruised barley- sprouts) on day 56 than in group 1.

Effect of full-length and truncated IgY on the nutritional cost of infection in mallard ducks (Anas platyrhynchos)

B.D. Humphrey, C.C. Calvert, K.C. Klasing

Department of Animal Science, University of California, Davis, CA. 95616

During the initial stages of infection, a series of metabolic and behavioral changes occur within an animal that are collectively referred to as the acute phase response (Suffredini et al., 1999). These changes include anorexia, lethargy, somnolence, and repartitioning of nutrients away from growth and other physiological processes and toward immunological processes (Klasing, 1988). Collectively, the acute phase response results in a detrimental impact on growth and nutrition-related physiology by altering body conditioning and energy metabolism. Ducks (Anas platyrhynchos) produce two isoforms of the immunoglobulin n-chain; a full-length isoform (IgY), and a truncated isoform (IgYDFc) lacking a Fc region responsible for mediating most effector functions (Warr et al., 1995). The lack of a Fc region would presumably weaken the ability of the IgY(DFc) isoform to stimulate the acute phase response, and consequently minimize nutritional losses associated with fighting infection. To examine this relationship, fixed Escherichia coli-antibody complexes with various ratios of IgY:IgY(DFc) (100%:0; 50%:50%; 0:100%; 0:0 [-control]) were injected intravenously into naïve mallard ducks and the acute phase protein hemopexin and IL-1b mRNA levels were determined. E. coli-antibody complexes were injected intravenously into the femoral vein and serum was collected at 0 and 24 hours for hemopexin analysis, while liver and spleen samples were collected at 2-h post-injection for determination of IL-1b mRNA expression. Hemopexin and liver IL-1b mRNA levels were significantly effected by treatment with ratios of IgY:IgY(DFc) at 100:0 and 0:100 resulting in their highest production (P<0.05). Spleen IL-1b mRNA decreased directly with increasing IgY(DFc) (P<0.05), and IgY:IgY(DFc) ratio of 0:100 did not differ from no immunoglobulin (- control). These results indicate that the absolute ratio of IgY:IgY(DFc) results in differential regulation of the acute phase response across organs, and that equimolar ratios of the two isoforms serve to down-regulate the acute phase response and nutritional costs of infection. The predominance of IgY(DFc) upon repeated exposure to antigen represents a unique immunological niche in mallard ducks not found in mammalian or chicken systems that can serve as a model to explore the impact of mounting an immune response on the nutritional status of an animal.

Klasing, K. C. 1988. Journal of Nutrition 118: 1436-1446. Suffredini, A. F., et al. 1999. Journal of Clinical Immunology 19(4): 203-214. Warr, G. W., et al. 1995. Immunol Today 16(8): 392-398.

Systemic and pulmonary antioxidant status in equine recurrent airway obstruction (RAO)

D.J. Marlin 1 , C.M. Deaton 1 , N.C. Smith 1 , P.A. Harris 2 , R.C. Schroter 3 & F.J. Kelly 4

1 Animal Health Trust, Lanwades Park, Kentford, Suffolk, UK. 2 Equine Studies Group, WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Leicestershire, UK. 3 Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK. 4 School of Health & Life Sciences, King's College London, London, UK.

Recurrent airway obstruction (RAO, formerly known as equine chronic obstructive pulmonary disease, COPD) is a condition with many similarities to human asthma and has been estimated to be the most common medical condition of horses in Northern Europe. Recently we have reported that ascorbic acid (AA) is the major non-enzymatic antioxidant in equine epithelial lining fluid (ELF) and is markedly reduced in RAO-affected horses in crisis (i.e. with marked airway inflammation). Here we present systemic and pulmonary ascorbic acid and glutathione measurements in RAO-affected horses in both crisis and remission. Remission being defined as bronchoalveolar lavage [BAL] neutrophil numbers less than 20 cells/µl).
Non-RAO (controls) n=8
RAO (Crisis)
RAO (Remission)
Plasma AA (umol/l) 19.5 ± 4.6 a 7.2 ± 1.0 b 8.6 ± 2.1 b
Plasma ARR (%) 0.8 ± 1.7 a 8.2 ± 7.3 b 10.9 ± 3.5 b
ELF AA (mmol/l) 2.0 ± 0.7 a 0.3 ± 0.4 b 1.1 ± 0.7 ab
ELF DHA (mmol/l) 0.1 ± 0.2 a 0.4 ± 0.5 a 0.1 ± 0.1 a
ELF tAA (mmol/l) 2.1 ± 0.7 a 0.7 ± 0.4 b 1.2 ± 0.6 b
ELF ARR (%) 6.7 ± 9.2 a 57.4 ± 46.3 b 11.9 ± 15.2 a
RBC GSH (mmol/l) 1.26 ± 0.25 a 1.39 ± 0.38 a 1.29 ± 0.40 a
RBC GRR (%) 3.2 ± 1.5 a 5.0 ± 0.6 a 4.0 ± 0.7 a
ELF GSH (µmol/l) 52 ± 13 a 39 ± 52 a 132 ± 63 b
ELF GSSG (µmol/l) 5 ± 4 a 41 ± 40 b 8 ± 4 ab
ELF TGSH (µmol/l) 57 ± 12 a 80 ± 42 ab 140 ± 64 b
ELF GRR (%) 9.1 ± 8.4 a 60.6 ± 42.5 b 6.6 ± 3.4 a
BAL neutrophils (%) 3 ± 2 a 24 ± 22 b 2 ± 2 a
BAL neutrophils (/µl) 8 ± 5 a 28 ± 11 b 3 ± 2 a
AA ascorbic acid; DHA dehydroascorbic acid; tAA = AA+DHA; ARR ascrobate redox ratio (DHA/tAA*100); GSH reduced glutathione; GSSG oxidised glutathione; TGSH (GSH+GSSG); GRR glutathione redox ratio (GSSG/TGSH*100). Differences between groups significant at least at P<0.05 (ANOVA). Cells in same row with different superscripts differ by at least P<0.05 (Newman-Keuls). RAO affected horses in crisis have significantly increased numbers of neutrophils in BAL and show evidence of both systemic and pulmonary oxidative stress based on plasma ARR and ELF ARR and GRR compared with non-RAO affected controls. In remission, when the BAL neutrophil numbers are no longer elevated, ELF ARR and GRR are not different from non-RAO affected controls. However, plasma AA and ELF tAA are still lower and plasma ARR, ELF GSH and TGSH are increased compared with the non-RAO affected controls. In RAO-affected horses in remission, systemic oxidative stress persists and may no longer be related to pulmonary events. However, despite an absence of pulmonary oxidative stress, there is decreased AA status, which is only partially compensated for by a small increase in GSH.

Antioxidant Supplementation in Horses Affected by Recurrent Airway Obstruction

C.M. Deaton 1 , D.J. Marlin 1 , N. Smith 1 , P.A. Harris 2 , F. J. Kelly 3 and R.C. Schroter 4

1 Centre for Equine Studies, Animal Health Trust, Kentford, Suffolk, CB8 7UU, UK 2 Equine Studies Group, WALTHAM Centre for Pet Nutrition, UK. 3 School of Health & Life Sciences, King's College London, UK 4 Department of Bioengineering, Imperial College of Science, Technology and Medicine, UK

Recurrent airway obstruction (RAO, formerly known as equine chronic obstructive pulmonary disease, COPD) is an asthma-like condition of the horse characterised by periods of acute airway inflammation, pulmonary oxidative stress and bronchoconstriction (crisis), and periods of remission. We have previously demonstrated that ascorbic acid is quantitatively the major non-enzymatic antioxidant in equine pulmonary epithelial lining fluid (ELF). In addition, the concentration of ascorbic acid in plasma and ELF is significantly reduced in RAO-affected horses in both crisis and remission compared to healthy controls. We therefore studied the effects of a dietary supplement containing a mixture of natural antioxidants including vitamin E, ascorbic acid and selenium (WINERGY® VENTILATE TM ). Using a cross-over design study with a four week washout period, the supplement was provided for four weeks, during which we examined its effects on the systemic and pulmonary antioxidant status in five RAO-affected horses in clinical remission. The horses were housed in stables and performed regular exercise. Remission was defined as bronchoalveolar lavage neutrophil numbers less than 20 cells/ml. Antioxidant supplementation significantly increased the plasma ascorbic acid oncentration (21 ± 4 mmol/l) compared to a placebo (11 ± 3 mmol/l, p < 0.05), but had no effect on the ELF concentration of ascorbic acid (2.9 ± 3.0 mmol/l and 1.5 ± 0.9 mmol/l, respectively) or the plasma and ELF concentrations of dehydroascorbate (the oxidised form of ascorbic acid). The concentration of glutathione in red blood cell haemolysate and ELF was also unaffected by antioxidant supplementation, however the concentration of oxidised glutathione (GSSG; 14 ± 24 mmol/l) in ELF was significantly reduced compared to the placebo (39 ± 54 mmol/l, p < 0.05). In summary, antioxidant supplementation increased the concentration of plasma ascorbic acid in RAO-affected horses in clinical remission, such that the concentration was similar to that of healthy horses, but had no significant effect on the concentration of the major non-enzymatic antioxidants in ELF over the time period studied. However the supplement did reduce the concentration of GSSG in the ELF, suggesting that the antioxidant supplement decreased the degree of pulmonary oxidative stress.

Effects of Tasco (a brown seaweed) and heat stress on immune function and antioxidant activity of wether lambs

K.E. Saker 1 , J.H. Fike 2 , H.P. Viet 1 , D.L. Ward 1 . 1 VA-MD Regional College of veterinary

Medicine and 2 Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA

Over the years investigators have attempted to overcome the endophyte fungus-associated production and health consequences (fescue toxicosis) to livestock managed on tall fescue (Festuca arundinacia, Schreb.) with minimal success. Recent work indicates a reversal of adverse clinical signs and diminished immunocompetence in livestock endophyte-infected (EI) tall fescue treated with a brown seaweed extract, Tasco. Grazing and feedlot-finishing study data demonstrates improved animal health and carcass quality, most likely via an antioxidant related mechanism.3, 4 To date, the effects of Tasco supplementation to post-harvest forage have not been reported for livestock production systems. The purpose of our study was to evaluate select innate immunity and oxidative stress in response heat stress in a Tasco-fescue hay system.

EI tall fescue-based pasture received 0 or 3kg/ha of Tasco-Forage (an extract of the brown seaweed Ascophyllum nodosum) prior to harvest and was compared to direct-feeding Tasco-EX (an extract of A. nodosum in liquid form). Twenty-eight wether lambs (initial avg BW 40 kg), blocked by weight, were randomly assigned to one of three diets. Diets were 1) control hay, 2) treated hay, and 3) #1 + Tasco-EX fed at an additional 1% of the as-fed diet. Heat stress was applied for 10 d following a 27-d diet adjustment period with measurements obtained at d4 and 10.

Tasco-EX application increased monocyte phagocytic activity (P=0.01) in lambs compared with pre-harvest (Tasco-Forage) and control diets. Heat stress influenced cell activity across all treatments (P<0.0001). Phagocytic cells obtained from Tasco-EX treatment lambs exhibited increased (P<0.05) capacity for oxidative burst as compared to Tasco-Forage and control lambs. Phagocytes obtained from the Tasco-EX lambs maintained their capacity for oxidative burst throughout the 10 d heat stress period (P<0.01). Cell function decreased in response to heat in control and Tasco-Forage lambs. A heat x diet interaction was apparent (P=0.10). Superoxide dismutase (SOD) and glutathione peroxidase (GPx) was consistently higher in leukocytes from lambs on both Tasco-treatments vs control during heat stress periods. Minimal (P<0.001) cell peroxidation occurred during heat stress due to Tasco-EX treatment.

Pre-harvest treatment with Tasco-Forage to tall fescue appeared to provide residual effects on animal antioxidant availability in short-duration (4-d) heat stress. Post-harvest Tasco-EX supplementation to tall fescue hay enhanced immune function in wether lambs and protected them against prolonged heat-induced oxidative stress. Hay treatment with Tasco has the potential to provide substantial health benefits to ruminants in sub-optimal production scenarios.

3 Saker, et al, 2001. J Anim Sci 79:1022-1031. 4 Allen, et al., 2001. J Anim Sci 79(E. Suppl.):E21-31.

Influence of lactulose as feed additive on chyme composition and intestinal microflora in pigs infected artificially with E. coli O139:K82 and Salmonella Derby

S. Bollmann 1 , O. Stuke 2 , R. Tabeling 2 , J. Kamphues 2 , G. Amtsberg 1

1 Institute of Microbiology and Infectious Diseases, School of Veterinary Medicine Hannover 2 Institute of Animal Nutrition, School of Veterinary Medicine Hannover

By addition of lactulose as prebiotic to the diet benefits are expected for growth and increase of bifidobacteria and lactobacilli, while clostridia, E. coli and salmonella should be inhibited. In a study with weaned piglets Sutton and Patterson (1996) observed a reduced concentration of E. coli (K88 + ) on days 6-10 following to weaning when fed 1% lactulose. Also in a field study with salmonella infected fattening pigs (Wiemer 1999) lactulose (0.7 g/kg BW) caused a significant reduction of salmonella excreting pigs in herds. Aim of the study was to investigate the potential of lactulose to prevent the incidence of edema disease in weaning piglets and to reduce the excretion and translocation (from the intestine to other tissues) of Salmonella Derby in fattening pigs.

The pigs were offered a starter diet ad libitum containing 5 % lactulose preparation (2.51 % lactulose) for treatment groups and corn starch in exchange for the control groups (per kg DM: 15.2 MJ ME; 170 g crude protein; 33 g crude fiber). Five days post weaning 20 piglets (two groups each of 5 treatment and 5 control piglets; Ø 7.6 kg BW) were orally infected with E. coli 0139:K82 (1. group: 3.7*10 9 cfu; 2. group 2.3*10 10 cfu). For the study on Salmonella Derby fattening pigs (Ø 60.6 kg BW) received an infective dose of 2,6x 10 9 cfu per os. Feed intake, animal health as well as the dry matter content and pH-value of faeces were controlled daily. Also counts of E. coli O139:K82 and qualitative analysis of Salmonella Derby in faeces were measured (culture method) on several days. Pigs without clinical signs of edema disease were killed 8 days post E. coli infection. Observation of Salmonella Derby infected animals lasted up to 42 days. The removed intestinal tract was divided into stomach, small intestine (part 1-3), caecum, colon ascendens and rectum. In the chyme dry matter content and pH-value, concentrations of short chain fatty acids, ammonia, l-lactat were estimated. Also counts of bifidobacteria and E. coli/Salmonella Derby were estimated. Additionally for fattening pigs the translocation of Salmonelly Derby into ln. jejunalis, ln. ileocolici and the tonsils were investigated by enrichment method. Results: No differences were determined for feed intake, dry matter content and fecal pH, but in several parts of the intestinal tract pH-values and the concentration of ammonia were significantly lower in the treated groups. In both of E. coli infected groups the counts of E. coli in faeces and number of piglets showing clinical signs of edema disease were similar. A higher number of E. coli O139:K82 was observed in colonic chyme of piglets with apparent edema disease than in healthy controls. In Salmonella Derby infected fattening pigs excretion and the frequency of translocation were similar for treated and control pigs. More pigs of the treatment group than controls showed Salmonella Derby in samples of small intestinal (part 3) and colon mucosa and chyme. The counts of bifidobacteria in intestinal chyme (small intestine part 3, colon) were similar in both groups.

These experiments with artificial infection failed to demonstrate positive ffects
of lactulose addition to the diet on the incidence of edema disease in weaned piglets and the excretion and translocation of Salmonella Derby in fattening pigs. Preventive effects of lactulose on colonisation by these pathogenic bacteria were not observed.

Sutton A. L. and J. A. Patterson, 1996. 5 th Int. Symposium on Animal Nutrition, Kaposvár, Hungary, 31-61 Wiemer F., 1999. Thesis, School of Veterinary Medicine Hannover

Dietary effects on bifidobacteria and Clostridium perfringens in canine faeces

Jürgen Zentek 1, 2 , Bettina Marquart 2 , Tanja Pietrzak 2 , Olivier Ballèvre 3 , Florence Rochat 3

1 Veterinary University of Vienna, 2 School of veterinary medicine Hanover, 3 Nestlé Research Centre Lausanne

Dietary effects on the intestinal microflora have gained increasing interest due to the increasing evidence that a balanced microecology in the gut is important for health and well being. Bifidobacteria are considered as representing the ‘beneficial’ bacteria whereas Clostridium perfringens may have negative impacts on the digestive system. The composition of the diet is one of the key factors for the control and the balance of this intestinal ecosystem. The aim of the present study was to evaluate the effect of two different diets on faecal Bifidobacteria and Cl. perfringens. The diets fed differed in the level and quality of protein, as well as in the presence or absence of a prebiotic fibre source.

Material and methods:
Two extruded, dry diets, one supplemented with 1.5% non digestible oligosaccharides (NDO) and the other with 3 % glucose (Glu) were compared to a protein rich wet diet (PR+) based on low quality animal derived protein sources. Nutrient compositions are given in table 1. Nine adult beagles or beagle-mongrels (age 8.7±2.0 years; body weight 11.7±1.9 kg) were randomly assigned to 2 groups (A and B). The feeding schedule was designed as a consecutive cross over trial with each feeding period lasting 3 weeks. All dogs started with diet PR+, after which group A dogs received Glu and B dogs received NDO. After an intermediate wash-out period with diet PR+ for 3 weeks the A dogs were switched to NDO and B dogs were switched to Glu. In the final period all dogs were fed with diet PR+. In all experimental periods faecal consistency was scored using a 5 point visual scale scoring system (1= hard, crumbly faeces, 3 = ideal, 5= watery diarrhoea). Additionally fecal samples were collected during each period for dry matter and pH measurements. Fecal bifidobacteria and Cl. perfringens were quantified at the end of each feeding period.

Consumption of dry diets increased faecal dry matter and reduced fecal pH from 6.9-7.4 with the high protein diet to 5.9-6.5 with the dry diets. The dry diets induced a firmer faecal consistency, with no significant difference between NDO or Glu. Cl. perfringens was found in all faecal specimens after feeding PR+ with bacterial counts of log 8.2 - log 8.8 cfu/ g faeces. Both dry diets reduced the counts of Cl. perfringens significantly (log 3.3-4.0 cfu/g faeces). Switching from the dry diets to the high protein wet diet induced an increase of Cl. perfringens within 1 day, independent of the previous diet. In dogs fed PR+, bifidobacteria were detected in only four faecal samples and exclusively in the initial feeding period. During the remainder of the experiment the counts fell below the detection limit (log 3.3 cfu/g feces). The faecal concentrations of bifidobacteria increased with both dry diets. Slightly higher concentrations (log 9.6 - log 9.7cfu/ g faeces) were obtained from dogs fed the dry diet containing NDO compared to the diet containing glucose (log 9.3 - log 9.4cfu/ g faeces). The small increase may be related to the low level of NDO added to the diet as well as to the rapid switch between diet. In conclusion, the study demonstrates a clear antagonistic pattern of bifidobacteria and Cl. perfringens in dogs. A low protein diet favoured the growth of bifidobacteria and reduced the faecal levels of Cl. perfringens significantly. These results suggest that the higher carbohydrate level favors a higher rate of fermentation with a decrease in fecal pH, which stimulates the growth of bifidobacteria.

Table 1: Protein, fat and fibre concentrations in
the experimental diets (g/kg, dry matter basis)
Crude protein 726 265 250
Crude fat 124 106 120
Crude fibre 36.9 23.3 24.0

Dietary resistant starch supplementation restores the integrity of rat inflamed colonic mucosa

N.Moreau a , L.Martin a* , C.Toquet b , C.Laboisse b , B.Siliart a , P.Nguyen a , .Champ c and H.Dumon a .

a National Veterinary School of Nantes, Nutrition and Endocrinology Unit (France), b Pathologic natomy Unit, CHU of Nantes (France), c National Institute of Agronomic Research, Digestive Functions and Human Nutrition Laboratory, Nantes (France).*corresponding author.

End-products of the cæco-colonic microbial fermentation of dietary fibres, acetate, propionate and butyrate represent the main short-chain fatty acids (SCFAs). Among them, butyrate presents prophylactic and therapeutic interest in the pathogenesis of inflammatory bowel diseases (IBD). Some dietary substrates such as resistant starch (RS) (type 3, Novelose 330 â ) are known to yield high levels of colonic butyrate and would be a promising alternative in IBD treatment. The aim of the present study was to evaluate the effect of RS on the cæco-colonic mucosa of rats with induced colitis. Involved in fibre effect, SCFAs were also investigated. Materials and methods : A chronic active colitis was induced in 24 rats with a extran Sulfate Sodium (DSS) treatment [5% for 7 days then 3% DSS for 7 or 14 days]. During the chronic phase of colitis (3% DSS), rats were fed ad libitum a fibre-free basal diet (BD) for 7 days (BD-7) or 14 days (BD-14) or the same diet supplemented with 6% RS for 7 days (RS-7) or 14 days (RS-14). Cæco-colonic inflammation was assessed macroscopically, histologically and by measurement of myeloperoxidase (MPO) activity, an index of neutrophil infiltration into the distal inflamed tissue. Intestinal permeability was assessed by urinary recovery of iodixanol measured by high performance liquid chromatography (the greater the amount recovered, the more increased the permeability is). SCFAs were quantified in cæco-colonic contents by gas chromatography.

The RS enriched diet restored part of the integrity of the inflamed mucosa. Indeed, we observed a significant decrease in macroscopic and histological scores, in MPO activity and in iodixanol permeability in RS groups compared to BD groups : BD-7 RS-7 P value BD-14 RS-14 P value Macroscopic score 6.6±1.1 6.8±1.2 NS 6.7±0.9 2.7±0.6 0.0022 Histological score 17.0±1.2 0.9±0.6 0.0035 15.5±0.5 11.6±1.1 0.0042 MPO activity (U -1 .g tissue) 123.3±27.2 55.5±11.6 0.0019 93.3±20.6 56.6±8.9 0.0419 Urinary Iodixanol (mg) 154.2±47.7 75.3±17.1 0.0255 92.5±29.7 29.8±5.8 0.0036 SCFAs and particularly butyrate (in micromoles) measured in cæco-colonic contents were significantly increased in the cæcum of RS-7 and RS-14 rats compared to BD-7 and BD-14 rats respectively.

A diet enriched with resistant starch (RS3) improves digestive inflammatory injuries induced by DSS in the rat’s colon. This RS effect could be partially explained by a higher concentration of SCFAs, particularly butyrate, in the digestive contents. This confirms the interest of butyrogenic fibres in IBD treatment.