Effects of fish oil supplementation on the performance and the immunological, adrenal, and somatotropic responses of weaned pigs after an Escherichia coli lipopolysaccharide challenge1

Duration of feeding linseed diet influences expression of inflammation-related genes and growth performance of growing-finishing barrows

The aim of the study was to investigate the effects of dietary linseed (rich in n-3 PUFA) on expression of inflammation-related genes and on growth performance of growing-finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, one as the basal diet and the other containing 10% linseed. Twenty-four Landrace x Yorkshire barrows weighing 35 +/- 3.7 kg were randomly assigned to 1 of 4 treatment groups, with 6 pigs per group. During the entire experimental period of 90 d, these 4 groups of pigs were first fed the basal diet and then fed the linseed diet for 0, 30, 60, and 90 d before slaughter, respectively. Pig growth; messenger RNA (mRNA) expression of peroxisome proliferator-activated receptor-gamma (PPARgamma), IL-1beta0, IL-6, and tumor necrosis factor-alpha (TNF-alpha); and plasma concentrations of the 3 proinflammatory cytokines were measured and analyzed. Average daily feed intake did not differ among treatment groups (P > 0.05), but ADG (P < 0.05) and G:F (P < 0.01) responded quadratically to the duration of linseed diet feeding, and pigs in the 60-d treatment group had the greatest ADG and G:F. The mRNA expression of PPARgamma in loin muscle and spleen increased linearly (P < 0.01) with the duration of linseed diet feeding, whereas its expression in adipose tissue was not affected (P = 0.095). Tumor necrosis factor-alpha and IL-6 mRNA expression in muscle, adipose, and spleen, as well as serum concentration of TNF-alpha, decreased linearly (P < 0.01) with the duration of linseed diet feeding. Peroxisome proliferator-activated receptor-gamma mRNA abundance was negatively correlated with IL-1beta, IL-6, and TNF-alpha mRNA abundance both in muscle (R(2) = 0.63, P < 0.001) and in spleen (R(2) = 0.69, P < 0.001), and PPARgamma mRNA expression in spleen (R(2) = 0.59, P < 0.01) and muscle (R(2) = 0.52, P < 0.05) was negatively correlated with serum TNF-alpha concentration. There were also significant quadratic relations between ADG and expression of PPARgamma (P < 0.05) and splenic TNF-alpha (P < 0.05). These data suggest that intake of n-3 PUFA from the linseed diet led to significant decreases in the expression of proinflammatory cytokine genes, which may stimulate growth in growing-finishing barrows, at least in part, through a PPARgamma-dependent mechanism.

Increased expression of the peroxisome proliferator-activated receptor gamma in the immune system of weaned pigs after Escherichia coli lipopolysaccharide injection

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, has been implicated in regulation of immunity and inflammation in rodents and humans. The objective of the current study was to investigate whether the expression of PPARgamma was altered in the immune system of weaned pigs after Escherichia coli lipopolysaccharide (LPS) injection. PPARgamma expression was investigated in the thymus, spleen, mesenteric lymph node and peripheral white blood cells of weaned pigs (8.54+/-0.24 kg BW) after LPS injection (100 microg/kg BW, n=6) and controls (sterile saline, n=6), by using real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Plasma pro-inflammatory cytokines and hormones were also assessed. LPS triggered PPARgamma mRNA and protein expression in the thymus (P<0.05, 4.24-fold; P<0.10, 1.46-fold), spleen (P<0.10, 2.75-fold; P<0.05, 1.84-fold), mesenteric lymph node (P<0.05, 4.32-fold; P<0.05, 1.96-fold) and peripheral white blood cells (P<0.001, 24.44-fold; P<0.001, 1.58-fold). The LPS-injected pigs showed an increase in PPARgamma staining in splenic corpuscle and periarterial lymphatic sheath of white pulp (P<0.05) and red pulp (P<0.001) of spleen, and in medullas of thymus lobule of thymus (P<0.05), and in thymus-dependent area of mesenteric lymph node (P<0.05) compared to the control pigs. Concurrent with up-regulation of PPARgamma expression, LPS induced increases in plasma interleukin-6 (P<0.001), tumor necrosis factor-alpha (P<0.001), cortisol (P<0.001), prostaglandin E(2) (P<0.01) and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15 d-PGJ(2)) (P<0.05), and decreases in plasma insulin (P<0.10) and insulin-like growth factor-1 (P<0.001). These results suggest that induction of PPARgamma expression in immune system may be associated with the release of the natural PPARgamma activating ligand 15 d-PGJ(2), and play an important role in host response to immunological stress. Additionally, it is possible that PPARgamma would be a new therapeutic target in treatment of immunological stress of livestock.

Dietary arginine supplementation alleviates intestinal mucosal disruption induced by Escherichia coli lipopolysaccharide in weaned pigs

This study evaluated whether arginine (Arg) supplementation could attenuate gut injury induced by Escherichia coli lipopolysaccharide (LPS) challenge through an anti-inflammatory role in weaned pigs. Pigs were allotted to four treatments including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS+0.5 % Arg; (4) LPS+1.0 % Arg. On day 16, pigs were injected with LPS or sterile saline. At 6 h post-injection, pigs were killed for evaluation of small intestinal morphology and intestinal gene expression. Within 48 h of challenge, 0.5 % Arg alleviated the weight loss induced by LPS challenge (P = 0.025). In all three intestinal segments, 0.5 or 1.0 % Arg mitigated intestinal morphology impairment (e.g. lower villus height and higher crypt depth) induced by LPS challenge (P < 0.05), and alleviated the decrease of crypt cell proliferation and the increase of villus cell apoptosis after LPS challenge (P < 0.01). The 0.5 % Arg prevented the elevation of jejunal IL-6 mRNA abundance (P = 0.082), and jejunal (P = 0.030) and ileal (P = 0.039) TNF-alpha mRNA abundance induced by LPS challenge. The 1.0 % Arg alleviated the elevation of jejunal IL-6 mRNA abundance (P = 0.053) and jejunal TNF-alpha mRNA abundance (P = 0.003) induced by LPS challenge. The 0.5 % Arg increased PPARgamma mRNA abundance in all three intestinal segments (P < 0.10), and 1.0 % Arg increased duodenal PPARgamma mRNA abundance (P = 0.094). These results indicate that Arg supplementation has beneficial effects in alleviating gut mucosal injury induced by LPS challenge. Additionally, it is possible that the protective effects of Arg on the intestine are associated with decreasing the expression of intestinal pro-inflammatory cytokines through activating PPARgamma expression.

Effects of fish oil on the neuro-endocrine responses to an endotoxin challenge in healthy volunteers

BACKGROUND & AIMS

Fish oil (FO) has been shown to modulate the acute and chronic inflammatory responses. Endotoxin (LPS) has been shown to mimic several aspects of sepsis. The study aimed at testing the effects of oral FO supplements in healthy subjects submitted to intravenous LPS on systemic and endocrine response.

SUBJECTS AND METHODS

Fifteen healthy men (aged 26.0+/-3.1 years, BMI 23.8+/-1.9 kg/m2), were enrolled. Subjects were randomised to 3-4 weeks of oral FO supplementation (7.2 g/day, providing 1.1 g/day of 20:5 (n-3) and 0.7 g/day of 22:6 (n-3) fatty acids) or no supplementation and then submitted to endotoxin challenge: 2 ng/kg of LPS. All subjects were studied twice (placebo and LPS).

MEASUREMENTS

vital signs, energy expenditure (EE), glucose and lipid metabolism ((2)H2-glucose), plasma cytokines and stress hormones for 6 h after LPS or placebo.

RESULTS

LPS caused cytokine release, fever, increases in heart rate, resting EE and substrate oxidation, plasma glucagon and glucose concentrations; the neuro-endocrine response was characterised by increased plasma stress hormones. FO significantly blunted fever, ACTH and cortisol plasma levels (no effect on cytokine release). FO blunted the peak norepinephrine after LPS.

CONCLUSION

FO supplements blunted the endocrine stress response and the increase in body temperature, but had no impact on cytokine production after LPS. These findings conflict with the postulated anti-inflammatory effects of FO on arachidonic acid metabolism and cytokine release. These results suggest that FO may exert beneficial effects in sepsis though non-inflammatory which require further investigations.

Effects of β-glucan obtained from the Chinese herb Astragalus membranaceus and lipopolysaccharide challenge on performance, immunological, adrenal, and somatotropic responses of weanling pigs1

A total of 108 crossbred piglets (7.75 +/- 0.24 kg of BW) weaned at 28 d was used to study the interactive effects of beta-glucan obtained from the Chinese herb Astragalus membranaceus (AM) and Escherichia coli lipopolysaccharide (LPS) challenge on performance, immunological, adrenal, and somatotropic responses of weaned pigs. The treatments were in a 2 x 3 factorial arrangement; main effects were level of Astragalus membranaceus glucan (AMG; 0, 500, or 1,000 mg/kg; as-fed basis) and presence of immunological challenge (with or without LPS). The experiment included six replicate pens per treatment and three pigs per pen. Lipopolysaccharide challenges were conducted on d 7 and 21 of the trial. Blood samples were obtained from the vena cava from one pig per pen at 3 h after LPS challenge to determine plasma responses. Weight gain and feed:gain ratio were unaffected by glucan. However, there was a quadratic effect on feed intake (P < 0.05): pigs fed 500 mg of glucan/kg had the highest feed intake. Immunological challenge with LPS decreased weight gain (P = 0.02). An interaction (P = 0.01 to 0.09) between AMG and LPS was observed for glucose, IL-1beta, PGE2, and cortisol. Astragalus membranaceus glucan had a quadratic effect on the plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) after both LPS challenges. Plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) were all increased in LPS-challenged pigs compared with the control pigs after both LPS challenges. The IGF-I concentrations were less for LPS-challenged pigs than for unchallenged pigs. The lymphocyte proliferation response of peripheral blood induced by 5 microg of concanavalin A/mL (P < 0.01) and IL-2 bioactivity (P < 0.05) increased linearly with increasing addition of glucan. Pigs challenged with LPS had greater T-lymphocyte proliferation (P = 0.06) and IL-2 bioactivity (P = 0.07) than unchallenged pigs after the first immunological challenge but not after the second. In conclusion, although glucan did not improve pig performance under the conditions of the present experiment, when included at 500 mg/kg, it decreased the release of inflammatory cytokine and corticosteroid and improved the lymphocyte proliferation response of weanling piglets via enhanced IL-2 bioactivity.