In chickens, elevated environmental temperature reduces food intake. We have previously reported that, during heat stress, the intestinal mucosa has an increased capacity to take up sugars. To investigate whether the effects of warm environment on sugar uptake are an intestinal adaptation to lower energy intake or a response attributable to heat stress, we examined the glucose transport kinetics of apical and basolateral membranes of the jejunum and the mucosal morphology of broiler chickens maintained in climatic chambers for 2 wk. Experimental groups were 1) control ad libitum (CAL), fed ad libitum and in thermoneutral conditions (20°C); 2) heat stress ad libitum (HSAL), fed ad libitum and kept in a heated environment (30°C); and 3) control pair-fed (CPF), maintained in thermoneutral conditions and fed the same amount of food as that consumed by the HSAL group. Both the CPF and the HSAL groups showed reduced body weight gain, but only the HSAL chickens had lower plasma thyroid hormones and higher corticosterone than CAL and CPF groups. The fresh weight and length of the jejunum were only reduced in the HSAL group. The activity and expression of apical sodium-dependent glucose transporter 1 (SGLT-1) were increased by ∼50% in the HSAL chickens, without effects in the CPF group. No changes in K_d or in SGLT-1 and glucose transporter-2 K_m were observed in the pair-fed and heated birds. These results support the view that increased intestinal hexose transport capacity is entirely dependent on adaptations of apical SGLT-1 expression to heat stress and is not due to reduced food intake.

In this study, we investigated intestinal barrier function during inflammation as well as the effects of dietary supplementation with porcine spray-dried animal plasma (SDAP) proteins and porcine immunoglobulin concentrate (IC). Wistar Lewis rats were fed from d 21 (weaning) until d 34 or 35 either a control diet or a diet containing SDAP or IC. On d 30 and d 33, rats received an intraperitoneal dose of Staphylococcus aureus enterotoxin B (SEB; 0.5 mg/kg body wt; groups SEB, SEB-SDAP, and SEB-IC). SEB reduced the potential difference across the jejunum by 60%, the short-circuit current by 70%, and Na-K-ATPase activity in intestinal mucosa (all P < 0.05). The fluxes of dextran flux (4 kDa) and horseradish peroxidase (HRP, 40 kDa) across the intestinal wall also increased in SEB-treated rats (P < 0.01, P = 0.068, respectively). SEB also increased HRP flux across the paracellular space (P < 0.05). Moreover, SEB-treated rats had a reduced expression of tight junction proteins, such as ZO-1 (10% reduction; P < 0.05) and β-catenin (20% reduction; P < 0.05). Dietary supplementation with SDAP or IC prevented dextran (P < 0.05) and HRP (P < 0.05) paracellular flux across the intestinal epithelium. SDAP supplementation also prevented SEB effects on Na-K-ATPase activity (P < 0.05). In our model of SEB-induced intestinal inflammation, the increased permeability across the intestinal mucosa was due to the lower expression of tight junction proteins, an effect that can be prevented by both SDAP and IC supplementation.

The aim of this study was to determine the potential modulatory effects of diets supplemented with spray-dried animal plasma (SDAP) or immunoglobulin concentrates (IC) on the immune response of rats challenged with Staphylococcus aureus enterotoxin B (SEB). Lewis rats were fed diets containing 80 g of SDAP/kg diet, 22.7 g of IC/kg diet, or milk proteins (Control diet) from postnatal d 21 (weaning) for 14 d. On d 30 and 33, rats were given SEB (0.5 mg/kg body weight; i.p.). Organized gut-associated lymphoid tissue (GALT) populations, intestinal secretion, mucosal and serum immunoglobulin concentrations, and neutrophil infiltration were studied. On d 35, blood was collected under anesthesia and samples of intestinal mucosa, Peyer's patches, mesenteric lymph nodes (MLN), and spleen were taken. SEB increased the water content of feces, which was prevented by diets containing either SDAP (P < 0.002) or IC (P < 0.001), indicating that plasma protein–supplemented diets can reverse the SEB-induced secretory response. In Peyer's patches, the diet containing SDAP partially prevented the SEB-induced increase in T lymphocytes (P < 0.1) and reduced the percentage of activated T helper cells (P < 0.05). In MLN, activated T lymphocytes were increased by SEB but they were not affected by diet. No effects of SEB or dietary supplementation on mucosal IgA and serum IgA and IgG were observed. The effects of SDAP supplementation on the lymphocyte populations of GALT in rats challenged with SEB support the view that SDAP can modulate the immune response and suggest that plasma protein supplementation can prevent GALT from possible activation by luminal bacterial superantigens.

In animal models of inflammation and in farm animals, dietary inclusion of spray-dried porcine plasma (SDP) reduces mucosal inflammation. Here, we study whether these effects could be mediated by changes in the intestinal microbiota and if these changes are similar to those induced by oral antibiotics. Weaned 21-day-old C57BL/6 mice were divided into 3 groups: the CTL group, fed the control diet; the COL group, administered low doses of neomycin and colistin; and the SDP group, supplemented with 8% SDP. After 14 days, analysis of the fecal microbiome showed that the microbiota profiles induced by SDP and the antibiotics were very different, thus, SDP has prebiotic rather than antibiotic effects. At the phylum level, SDP stimulated the presence of Firmicutes, considerably increasing the lactobacilli population. It also enhanced the growth of species involved in regulatory T-lymphocyte homeostasis and restoration of the mucosal barrier, as well as species negatively correlated with expression of pro-inflammatory cytokines. At the mucosal level, expression of toll-like receptors Tlr2, Tlr4 and Tlr9, and mucous-related genes Muc2 and Tff3 with regulatory and barrier stability functions, were increased. SDP also increased expression of Il-10 and Tgf-β, as well as markers of macrophages and dendritic cells eventually promoting an immune-tolerant environment.

Spray-dried preparations from porcine and bovine plasma can alleviate mucosal inflammation in experimental models and improve symptoms in patients with enteropathy. In rodents, dietary supplementation with porcine spray-dried plasma (SDP) attenuates intestinal inflammation and improves the epithelial barrier function during intestinal inflammation induced by Staphylococcus aureus enterotoxin B (SEB). The aim of this study was to discern the molecular mechanisms involved in the anti-inflammatory effects of SDP. Male C57BL/6 mice were fed with 8% SDP or control diet (based on milk proteins) for two weeks, from weaning until day 33. On day 32, the mice were given a SEB dose (i.p., 25 µg/mouse) or vehicle. SEB administration increased cell recruitment to mesenteric lymph nodes and the percentage of activated Th lymphocytes and SDP prevented these effects). SDP supplementation increased the expression of interleukin 10 (IL-10) or transforming growth factor- β (TGF-β) compared to the SEB group. The SEB challenge increased six-fold the expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) and intercellular adhesion molecule 1 (ICAM-1); and these effects were attenuated by SDP supplementation. SEB also augmented NF-κB phosphorylation, an effect that was prevented by dietary SDP. Our results indicate that the anti-inflammatory effects of SDP involve the regulation of transcription factors and adhesion molecules that reduce intestinal cell infiltration and the degree of the inflammatory response.

We investigated the intestinal transport of d-glucose (d-Glc) and 3 essential amino acids in a model of intestinal inflammation, and the effects of dietary supplementation with animal plasma proteins on this function. Wistar Lewis rats were fed a diet containing an isonitrogenous amount of milk protein (control group) or a diet supplemented with either spray-dried animal plasma (SDAP) or immunoglobulin concentrate (IC) from porcine plasma, from d 21 of life (weaning) until d 35. On d 30 and 33, rats were challenged intraperitoneally with Staphylococcus aureus enterotoxin B (SEB; groups SEB, SEB-SDAP, and SEB-IC) and on d 35, brush border membrane vesicles (BBMVs) were prepared and used for transport and binding studies. Administration of SEB reduced d-Glc transport across sodium glucose transporter 1 [SGLT1; 20% reduction in maximal transport rate (V_max); P < 0.05], without affecting the Michaelis constant (K_m). The results from specific phlorizin binding, Western blot, and immunohistochemistry supported the view that the effects of SEB are due to reduced expression of d-Glc transporters in the apical membrane. SEB increased the passive diffusion constant (K_d) for d-Glc 3-fold (P < 0.05). SEB did not affect mediated or passive amino acid fluxes of l-leucine, l-methionine, or l-lysine. Dietary SDAP increased the d-Glc V_max in the SEB group without affecting the passive component. Changes in d-Glc V_max due to SEB and to the dietary treatments were correlated with changes in the number of SGLT1 transporters present in the BBMVs (r = 0.9468; P < 0.05). Dietary IC had no observed effect. We estimate that, in rats challenged with SEB, SDAP supplementation can increase glucose absorption by 8–9% during the interdigestive periods.