Glucagon‐Like Peptide 2 Stimulates Postresection Intestinal Adaptation in Preterm Pigs by Affecting Proteins Related to Protein,Carbohydrate, and Sulphur Metabolism

Background: Exogenous glucagon‐like peptide 2 (GLP‐2) stimulates intestinal adaptation after resection in animal models of pediatric short bowel syndrome (SBS). It is unknown whether the molecular mechanisms of such GLP‐2 effects are similar to those of postresection spontaneous adaptation. Using preterm pigs as a model, we hypothesized that GLP‐2 treatment would change the intestinal proteome within the first week after resection, relative to individuals not resected or resected without GLP‐2 treatment. Materials and Methods: Two‐day‐old preterm pigs were subjected to resection of 50% distal small intestine and fed total parenteral nutrition without (SBS) or with GLP‐2 infusion (3.5 µg/kg/h, SBS+GLP‐2) for 5 days. The proteome of the remnant proximal intestine was compared among the SBS, SBS+GLP‐2, and unresected pigs, through gel‐based proteomics. Results: Thirty‐two proteins with differential expression were identified. Ten of these proteins were affected by the resection alone (ie, SBS vs unresected pigs). Five of these resection‐responsive proteins and another 22 proteins were affected by GLP‐2 infusion (ie, SBS+GLP‐2 vs SBS or unresected pigs). Resection alone mainly affected cellular structural proteins, while the added GLP‐2 treatment affected proteins involved in protein processing and the metabolism of protein, carbohydrate, and sulphur. Conclusion: In the first days following resection, proteins affected by resection plus GLP‐2 treatment differed markedly from those affected by the spontaneous intestinal adaptation following resection alone. Whether more long‐term GLP‐2 treatment may affect the intestinal proteome following intestinal resection remains unknown.     

Prematurity does not markedly affect intestinal sensitivity to endotoxins and feeding in pigs

Preterm neonates show enhanced sensitivity to nutrient maldigestion and bacteria-mediated gut inflammatory disorders, such as necrotising enterocolitis (NEC). We hypothesised that preterm birth increases the sensitivity of intestinal nutrient absorption to endotoxins and that feeding after birth reduces this response. Hence, we investigated the postnatal development of nutrient digestive and absorptive capacity in the preterm and term pig intestine, and its responsiveness to endotoxins. Pigs were delivered by caesarean section at preterm (n 20) or term (n 17) gestation, and the small intestine was collected at birth or after 2 d of colostrum feeding, followed by ex vivo stimulation with lipopolysaccharide endotoxins and mixed gut contents collected from pigs with NEC. Brush border enzyme activities were reduced in newborn preterm v. term pigs (39-45 % reduction, P < 0.05), but normalised after 2 d of feeding. Ex vivo leucine and glucose uptake increased with prenatal age. Bacterial stimulation reduced the nutrient uptake similarly at birth and after 2 d in preterm and term pigs (23-41 % reduction, P < 0.05), whereas IL-6 and TNF-α expression was stimulated only at birth. Toll-like receptor-4 expression increased markedly at day 2 for preterm and term pigs (22-33-fold, P < 0.05) but with much lower expression levels in newborn preterm pigs (approximately 95 %, P < 0.01). In conclusion, digestive and absorptive functions mature in the prenatal period, but are similarly affected by postnatal feeding and bacterial exposure in both preterm and term pigs. Nutrient maldigestion may contribute to NEC development, while a prematurity-related hyper-responsiveness to endotoxins could be less important, at least in pigs.     

Effects of Polymeric Formula vs Elemental Formula in Neonatal Piglets With Short Bowel Syndrome

Background: Intestinal adaptation is important for recovery in short bowel syndrome (SBS). This process is dependent on the presence of enteral nutrition (EN) and trophic factors, such as glucagon‐like peptide‐2 (GLP‐2). In clinical practice, elemental formula is often used to feed neonates with SBS, whereas animal studies suggest polymeric formula promotes better intestinal adaptation. In neonatal piglet models of SBS, with or without ileum, we compared the elemental with the polymeric formula, including the effect on endogenous GLP‐2. Materials and Methods: Forty‐eight piglets underwent 75% mid‐intestinal resection with jejunoileal anastomosis, 75% distal‐intestinal resection with jejunocolic anastomosis (JC), or sham without resection. Parenteral nutrition (PN) started postoperatively, tapering as EN was increased, according to clinical criteria, based on diarrhea and weight. Within groups, piglets were randomized to an isocaloric/isonitrogenous elemental (amino acid) or polymeric (intact protein) diet. Plasma GLP‐2 and histology for adaptation were measured at 14 days. Results: Within both SBS and control groups, no difference in adaptation was observed according to diet. A difference was observed only within the JC piglet group with regard to clinical outcomes. In these piglets, compared with elemental formula, the polymeric formula was associated with more diarrhea (P = .023) and longer duration of PN support (P = .047). Conclusion: An overall benefit of the polymeric formula over the elemental formula on gut adaptation was not observed. Furthermore, SBS piglets without ileum had less ability to tolerate polymeric formula, contributing to more days of PN support.     

Differential Effects on Intestinal Adaptation Following Exogenous Glucagon‐Like Peptide 2 Therapy With and Without Enteral Nutrition in Neonatal Short Bowel Syndrome

Background: We aim to study the efficacy of exogenously administered glucagon‐like peptide 2 (GLP‐2) on intestinal adaptation in 2 preclinical models of neonatal short bowel syndrome (SBS) according to remnant intestinal anatomy, with and without ileum. Furthermore, we aim to determine if this adaptive effect was potentiated with enteral nutrition (EN). Methods: Neonatal piglets were block‐randomized to 75% mid‐intestinal (JI group, retains ileum) or distal‐intestinal (JC group, has no ileum) resection or no resection (sham control) and GLP‐2 treatment (11 nmol/kg/d) or saline control for 7 days. Piglets received nutrition support, either 100% parenteral nutrition (PN; 0% EN, n = 32 in total) or 80% PN + 40% EN (n = 28 in total). Adaptation was assessed by morphological and histological changes, as well as RT quantitative polymerase chain reaction of nutrient transporters and tight junctional proteins and fat absorption. Data are analyzed by 3‐way analysis of variance (ANOVA) and 2‐way ANOVA per EN level. Results: GLP‐2 treatment lengthened villi, deepened crypts, and improved intestinal weight in the remnant intestine of JC piglets. EN was a more potent adaptive stimulus for JI piglets. Small intestinal lengthening occurred only in the JI group, when given EN. There was no difference in total fat absorption and messenger RNA expression of nutrient transporters and tight junctional proteins. Conclusions: GLP‐2 administration augmented structural adaptation in JC piglets with distal intestinal resection. Given JI anatomy, further stimulation by GLP‐2 treatment over innate adaptation and stimulation by EN was modest and restricted to ileum. The differential effect of GLP‐2 in neonatal SBS, depending on remnant anatomy, has important implications for clinical translation and planning of clinical trials.     

Dietary protein absorption of the small intestine in human neonates

Background: The intestine plays a key role in the absorption of dietary proteins, which determines growth of human neonates. Bowel resection in the neonatal period brings loss of absorptive and protective surface and may consequently lead to malabsorption of dietary nutrients. However, there are no data on net dietary protein absorption of the small intestine in the period after intestinal surgery in human neonates. We therefore evaluated dietary feeding tolerance and quantified net dietary protein absorption capacity of the small intestine in human neonates in whom a temporary jejunostomy or ileostomy was created. Methods: Seventeen patients were included in the study. We collected small intestinal outflow fluid at the level of the enterostomy weekly for 24–48 hours during weeks 3 through 6 postoperatively. Protein levels in the intestinal outflow fluid were determined by bicinchoninic acid (BCA) assay. Results: In 14 patients, an enteral intake of >100 mL/kg/d was reached at a median of 17 days (range, 8–32 days) postoperatively. Three patients did not reach this level within the study period. Overall, the net dietary protein absorption capacity was 70%–90% of the total enteral protein intake. Conclusions: This study demonstrates that the dietary protein absorption capacity of the small intestine is intact in most human neonates after intestinal surgery in a very critical period of their lives. Furthermore, our results do not support the use of hydrolyzed or elemental formula in newborns with an enterostomy to improve amino acid uptake.     

Colonic GLP‐2 is not Sufficient to Promote Jejunal Adaptation in a PN‐Dependent Rat Model of Human Short Bowel Syndrome

Background: Bowel resection may lead to short bowel syndrome (SBS), which often requires parenteral nutrition (PN) due to inadequate intestinal adaptation. The objective of this study was to determine the time course of adaptation and proglucagon system responses after bowel resection in a PN‐dependent rat model of SBS. Methods: Rats underwent jugular catheter placement and a 60% jejunoileal resection + cecectomy with jejunoileal anastomosis or transection control surgery. Rats were maintained exclusively with PN and killed at 4 hours to 12 days. A nonsurgical group served as baseline. Bowel growth and digestive capacity were assessed by mucosal mass, protein, DNA, histology, and sucrase activity. Plasma insulin‐like growth factor I (IGF‐I) and bioactive glucagon‐like peptide 2 (GLP‐2) were measured by radioimmunoassay. Results: Jejunum cellularity changed significantly over time with resection but not transection, peaking at days 3‐4 and declining by day 12. Jejunum sucrase‐specific activity decreased significantly with time after resection and transection. Colon crypt depth increased over time with resection but not transection, peaking at days 7‐12. Plasma bioactive GLP‐2 and colon proglucagon levels peaked from days 4‐7 after resection and then approached baseline. Plasma IGF‐I increased with resection through day 12. Jejunum and colon GLP‐2 receptor RNAs peaked by day 1 and then declined below baseline. Conclusions: After bowel resection resulting in SBS in the rat, peak proglucagon, plasma GLP‐2, and GLP‐2 receptor levels are insufficient to promote jejunal adaptation. The colon adapts with resection, expresses proglucagon, and should be preserved when possible in massive intestinal resection.     

Formula-feeding reduces lactose digestive capacity in neonatal pigs

The intestine of newborn pigs develops rapidly during the first days postpartum. We investigated if feeding milk replacer (infant formula) as an alternative to colostrum has compromising effects on nutrient digestive function in the neonatal period. Nineteen piglets born at term were assigned to one of four treatments: (1) newborn controls; (2) natural suckling for 24 h; (3) tube-fed formula for 24 h; (4) tube-fed porcine colostrum for 24 h. All three fed groups showed significant increases in small-intestinal and colonic weights, villous heights and widths, maltase and aminopeptidase A activities, and decreases in dipeptidylpeptidase IV activity, relative to newborn pigs. Following oral boluses of mannitol, lactose or galactose, formula-fed pigs showed significantly reduced plasma levels of mannitol and galactose compared with colostrum-fed pigs. Activity of intestinal inducible NO synthase and plasma levels of cortisol were significantly increased, whereas intestinal constitutive NO synthase and alpha-tocopherol were decreased in formula-fed pigs compared with colostrum-fed pigs. Although formula-fed pigs only showed minor clinical signs of intestinal dysfunction and showed similar intestinal trophic responses just after birth, as those fed colostrum, lactose digestive capacity was markedly reduced. We conclude that formula-feeding may exert detrimental effects on intestinal function in neonates. Formula-induced subclinical malfunction of the gut in pigs born at term was associated with altered NO synthase activity and antioxidative capacity.     

Preterm birth affects the intestinal response to parenteral and enteral nutrition in newborn pigs

Maturation of gastrointestinal (GI) function in neonates is stimulated by enteral nutrition, whereas parenteral nutrition induces GI atrophy and malfunction. We investigated whether preterm birth alters the GI responses to parenteral and enteral nutrition. Pigs were delivered either preterm (107 d gestation) or at term (115 d gestation) and fed total parenteral nutrition (TPN) or enteral sow's milk (ENT) for 6 d after birth. Immaturity of the preterm pigs was documented by reduced blood pH, oxygen saturation and neutrophil granulocyte function, impaired intestinal immunoglobulin G uptake from colostrum, and altered relative weights of visceral organs (small intestine, liver, spleen, pancreas, and adrenals). For both ages at delivery, increases occurred in pancreatic weight (30-75%) and amylase activity (0.5- to 13-fold) after birth, but much more in ENT than in TPN pigs (P < 0.05). Six days of TPN feeding was associated with reduced intestinal weight for both delivery groups (60% of values in ENT, P < 0.001), but only in term TPN pigs was the weight lower than at birth (-20%, P < 0.05). Likewise, it was only in term TPN pigs that intestinal maltase activity increased, compared with ENT, and the absorption of glucose and proline decreased. Only in preterm pigs did TPN feeding increase lactase activity (+50% compared with ENT, P < 0.05). For both delivery ages, the mRNA of lactase-phloridzin hydrolase and sodium-coupled glucose transporter 1 (SGLT-1) were increased in TPN, compared with ENT. In conclusion, the trophic effect of enteral vs. parenteral nutrition on the GI tract is also present after preterm birth, but the postnatal maturation of many GI functions is modified, compared with term birth. The effects of nutritional regimen on the maturation of the gut epithelium in neonates depend on gestational age at birth.     

Preterm birth affects the intestinal response to parenteral and enteral nutrition in newborn pigs

Maturation of gastrointestinal (GI) function in neonates is stimulated by enteral nutrition, whereas parenteral nutrition induces GI atrophy and malfunction. We investigated whether preterm birth alters the GI responses to parenteral and enteral nutrition. Pigs were delivered either preterm (107 d gestation) or at term (115 d gestation) and fed total parenteral nutrition (TPN) or enteral sow's milk (ENT) for 6 d after birth. Immaturity of the preterm pigs was documented by reduced blood pH, oxygen saturation and neutrophil granulocyte function, impaired intestinal immunoglobulin G uptake from colostrum, and altered relative weights of visceral organs (small intestine, liver, spleen, pancreas, and adrenals). For both ages at delivery, increases occurred in pancreatic weight (30-75%) and amylase activity (0.5- to 13-fold) after birth, but much more in ENT than in TPN pigs (P < 0.05). Six days of TPN feeding was associated with reduced intestinal weight for both delivery groups (60% of values in ENT, P < 0.001), but only in term TPN pigs was the weight lower than at birth (-20%, P < 0.05). Likewise, it was only in term TPN pigs that intestinal maltase activity increased, compared with ENT, and the absorption of glucose and proline decreased. Only in preterm pigs did TPN feeding increase lactase activity (+50% compared with ENT, P < 0.05). For both delivery ages, the mRNA of lactase-phloridzin hydrolase and sodium-coupled glucose transporter 1 were increased in TPN, compared with ENT. In conclusion, the trophic effect of enteral vs. parenteral nutrition on the GI tract is also present after preterm birth, but the postnatal maturation of many GI functions is modified, compared with term birth. The effects of nutritional regimen on the maturation of the gut epithelium in neonates depend on gestational age at birth.     

Formula Induces Intestinal Apoptosis in Preterm Pigs Within a Few Hours of Feeding

Background: Nutrition regimens influence postnatal small intestinal development, which shows prominent changes after 6 hours of suckling. Such influences are particularly important in preterm neonates as inappropriate feeding responses may predispose to gastrointestinal disorders such as necrotizing enterocolitis (NEC). The authors investigated the early morphological responses to enteral feeding, prior to the time period when a large proportion of preterm pigs normally develop clinical NEC symptoms. Methods: Preterm piglets (106‐107 days of gestation) were fed parenteral nutrition (PN) for 2 days with or without a subsequent 8‐hour or 17‐hour period of enteral nutrition (EN) with sow's colostrum or formula. Another group of piglets was delivered at 108–109 days of gestation and used for comparison to PN pigs before enteral feeding. Stereological measurements of the mucosal surface density and the volume densities of the tunica mucosa, tunica muscularis, proliferative, and apoptotic cells were made and related to microscopical NEC‐lesion score. In addition, villus length and crypt depth were measured. Results: PN‐fed piglets showed minimal PN‐induced mucosal atrophy, although their crypts were deeper, together with lower cell proliferation and higher apoptotic indices, than newborn (NB) unfed piglets. After PN, enteral feeding with colostrum, for just 8 hours, induced a rapid increase in the mucosal volume density while formula feeding was associated with an elevated number of both proliferating and apoptotic cells and a higher NEC lesion score than PN‐ or colostrum‐fed pigs. Conclusion: Enteral feeding of formula, for only a few hours, induces rapid enterocyte turnover and mucosal structural changes that may predispose to later development of NEC.     

Enteral feeding induces early intestinal adaptation in a parenterally fed neonatal piglet model of short bowel syndrome

Background: Successful small intestinal (SI) adaptation following surgical resection is essential for optimizing newborn growth and development, but the potential for adaptation is unknown. The authors developed an SI resection model in neonatal piglets supported by intravenous and enteral nutrition. Methods: Piglets (n = 33, 12–13 days old) were randomized to 80% SI resection with parenteral nutrition feeding (R‐PN), 80% SI resection with PN + enteral feeding (R‐EN), or sham SI transection with PN + enteral feeding (sham‐EN). In resected pigs, the distal 100 cm of ileum (residual SI) and 30 cm of proximal SI were left intact. All pigs received parenteral nutrition postsurgery. Enteral nutrition piglets received continuous gastric infusion of elemental diet from day 3 (40:60 parenteral nutrition:enteral nutrition). Piglets were killed 4, 6, or 10 days postsurgery. Results: By 10 days, R‐EN piglets had longer residual SI than R‐PN and sham‐EN pigs (P < .05). At days 6 and 10, R‐EN piglets had greater weight per length of intact SI (P < .05) and isolated mucosa (P < .05) compared to other groups. Greater gut weight in R‐EN piglets was facilitated by a greater cellular proliferation index (P < .01) by 4 days compared to other groups and greater overall ornithine decarboxylase activity vs R‐PN piglets (P < .05). Conclusions: This new model demonstrated profound SI adaptation, initiated early postsurgery by polyamine synthesis and crypt cell proliferation and only in response to enteral feeding. These changes translated to greater gut mass and length within days, likely improving functional capacity long term.     

In a Neonatal Piglet Model of Intestinal Failure,Administration of Antibiotics and Lack of Enteral Nutrition Have a Greater Impact on Intestinal Microflora Than Surgical Resection Alone

Background: Data are limited on how short bowel syndrome (SBS) affects the healthy developing intestinal microbiome, with even less assessing different SBS anatomical surgical models. This study was conducted to describe the “ileal” and “colonic” microflora in 2 surgical models of SBS. Materials and Methods: Neonatal piglets (2–5 days old) underwent intestinal resection, leaving the ileum (JI anatomy, n = 6) or removing the ileum and ileocecal valve (JC anatomy, n = 5), or sham surgery (sham; n = 4). JI, JC, and sham piglets commenced parenteral nutrition on day 0 and received ampicillin and trimethoprim‐sulfadoxine on days 0–4 for prevention of line sepsis. At day 7, ileal and colonic digesta were collected, and they were also collected from age‐matched sow‐fed piglets (n = 6). DNA extraction, sequencing, and annotation followed standard procedures. Results: Colonic and ileal bacterial genus diversity and relative bacterial abundance were greater (P < .05) in sow‐fed compared with JI, JC, and sham piglets; however, minor differences were observed in either location between sham, JI, and JC piglets and within the surgical model. In the colon, sow‐fed piglets had higher (P < .05) abundance of Lactobacillus (26%) and tended to have lower (P = .06) abundance of Enterococcus (<.1%) than JI, JC, or sham piglets, in which Lactobacillus and Enterococcus abundance averaged <.1% and 9%, respectively. Conclusions: Intestinal resection reduces bacterial diversity in the large bowel, and the difference is associated with the presence/absence of the ileum and ileocecal valve. The lack of enteral nutrition and antibiotic administration (ie, sow‐fed vs surgery) had a greater influence on the observed shift in diversity and relative abundance than intestinal resection.     

Teduglutide‐Stimulated Intestinal Adaptation Is Complemented and Synergistically Enhanced by Partial Enteral Nutrition in a Neonatal Piglet Model of Short Bowel Syndrome

Background: Teduglutide, a glucagon‐like peptide‐2 (GLP‐2) analogue, is available for long‐term use by parenteral nutrition (PN)–dependent adults to promote intestinal adaptation but is not approved for use in pediatric patients. The objective of this study was to assess teduglutide‐stimulated induced intestinal adaptation, potential synergies with partial enteral nutrition (PEN), and distinct temporal markers of adaptation in a neonatal piglet model of short bowel syndrome (SBS). Materials and Methods: Neonatal piglets (48 hours old; n = 72) underwent an 80% jejunoileal resection and were randomized to 1 of 4 treatment groups, in a 2 × 2 factorial design, with PN or PEN (80% standard PN/20% standard enteral nutrition) and teduglutide (0.1 mg/kg/d) or control. Piglets received nutrient infusions for 4 hours, 48 hours, or 7 days. Results: Teduglutide improved (P < .05) mucosal surface area (villus height: duodenum, jejunum, ileum; crypt depth: ileum, colon; proliferation: duodenum, jejunum, ileum; colon; apoptosis: jejunum, ileum, colon) and acute nutrient processing capacity (glucose: duodenum, jejunum, ileum; glutamine: duodenum, jejunum). These effects were complemented and synergistically enhanced by PEN in both site and timing of action. Structural adaptations preceded functional adaptations, but crypt depth remained a strong indicator of adaptation, regardless of time. Conclusions: The combination of teduglutide and PEN enhances intestinal adaptation beyond that of either therapy alone.     

Modulation of Intestinal Inflammation by Minimal Enteral Nutrition With Amniotic Fluid in Preterm Pigs

Background: Necrotizing enterocolitis (NEC) is a severe inflammatory disorder, associated with the difficult transition from parenteral to enteral feeding after preterm birth. We hypothesized that minimal enteral nutrition (MEN) with amniotic fluid (AF), prior to enteral formula feeding, would improve resistance to NEC in preterm pigs. Methods: Experiment 1: IEC‐6 cells were incubated with porcine (pAF) and human AF (hAF) to test AF‐stimulated enterocyte proliferation and migration in vitro. Experiment 2: Cesarean‐delivered, preterm pigs were fed parenteral nutrition and MEN with pAF, hAF, or control fluid (MEN‐pAF, MEN‐hAF, or MEN‐CTRL; all n = 9) for 2 days before tissue collection. Experiment 3: Preterm pigs were fed MEN diets as in experiment 2, but followed by 2 days of enteral formula feeding, which predisposes to NEC (NEC‐pAF, NEC‐hAF, or NEC‐CTRL; n = 10–12). Results: Both pAF and hAF stimulated enterocyte proliferation and migration in vitro. In experiment 2, MEN‐pAF and MEN‐hAF pigs showed increased body weight gain and reduced intestinal interleukin (IL)–8 and colonic IL‐6 levels, indicating reduced inflammatory response. In experiment 3, body weight gain was highest in the 2 groups fed AF as MEN, but NEC incidences were similar (NEC‐pAF) or increased (NEC‐hAF) compared with controls. Conclusions: Intake of pAF or hAF improved body growth and modulated intestinal inflammatory cytokines during a period of parenteral nutrition, but did not protect against later formula‐induced NEC in preterm pigs. Further studies are required to show if MEN feeding with species‐specific AF, combined with an optimal enteral diet (eg, human milk), will improve adaptation during the transition from parenteral to enteral feeding in preterm neonates.     

Intestinal ornithine decarboxylase in short bowel syndrome patients with oral diet

The major consequence of extensive intestinal resection is loss of absorptive surface area, which results in malabsorption of nutrients; this condition is known as short-bowel syndrome (SBS). Patients with extensive small intestinal resection and colectomy leading to jejunostomy have the most severe SBS. Ornithine decarboxylase (ODC) plays a central role in cell proliferation and in the process of gut adaptation. Polyamine synthesis in crypt cells mediates the action of extracellular growth factors on DNA synthesis and mitotic activity. The aim of this study was to examine ODC expression and activity, diamine oxidase (DAO) activity and polyamine levels in the jejunal mucosa and red blood cells of SBS patients with a jejunostomy. The study group consisted of 6 patients (4 men and 2 women, mean age 55.8+/-9.8 years), who had undergone extensive small bowel resection and colectomy. All patients were maintained on cyclic parenteral nutrition and non-restricted oral nutrition. Two groups of patients operated on for unrelated reasons were included as the jejunum control group (n=6) and the ileum control group (n=13). Non statistical differences were observed in polyamine levels of red blood cells versus the control group (spermidine: 21.0+/-3.6 vs. 17.7+/-1.1 and spermine: 17.1+/-8.6 vs. 13.2+/-1.6 nmol/ml RBC, respectively). No significant decreases in putrescine and spermidine levels were observed between the groups, but spermine levels in SBS jejunum were significantly lower than the controls (P<0.05). In SBS patients a significant decrease in ODC and DAO activity were observed vs jejunum. A significant decrease in ODC-mRNA abundance was found for the SBS patients as compared to the two control groups (P<0.05). These results suggest that in SBS patients with jejunostomy intestinal adaptation may be impaired.     

Parenteral and enteral feeding in preterm piglets differently affects extracellular matrix proteins, enterocyte proliferation and apoptosis in the small intestine

The preterm intestine is immature and responds differently to total parenteral nutrition (TPN) and enteral nutrition, compared with the term intestine. We hypothesised that in preterms, diet composition and feeding route affect mucosal morphology, enterocyte mitosis and apoptosis, and the distribution of laminin-1, fibronectin and collagen IV (extracellular matrix proteins (ECMP)). Preterm piglets (93.5 % of gestation) were delivered via caesarean section and birth weight-matched allocated to one of the four experimental groups: the piglets were either euthanised immediately after delivery, after 3 d of TPN or after 2 d enteral feeding with colostrum or milk formula, following 3 d of TPN. We combined immunohistochemistry, image analysis and stereological measurements to describe the intestinal mucosal layer. No significant changes occurred after 3 d of TPN. Feeding colostrum or milk replacer for 2 d after TPN was associated with an increased crypt depth. Only enteral feeding with colostrum resulted in an increased villus height and mitotic index. Neither TPN nor enteral feeding changed the distribution pattern of ECMP or the occurrence of bifid crypts. The immature distribution pattern of ECMP in TPN-fed piglets, coupled with unchanged enterocyte mitosis and apoptosis indices, illustrates that feeding preterm pigs 3 d TPN does not lead to mucosal atrophy. Despite the invariable distribution of ECMP, colostrum was associated with crypt hyperplasia resulting in an increased villus height. These data illustrate that some mechanisms regulating cell turnover are immature in preterms and may in part explain the abnormal gut responses to TPN and enteral feeding in prematurely born pigs.     

Surgical Anatomy Does Not Affect the Progression of Intestinal Failure–Associated Liver Disease in Neonatal Piglets

Background: Intestinal failure–associated liver disease (IFALD) causes significant morbidity in neonates with short bowel syndrome (SBS) dependent on parenteral nutrition (PN). Resected ileum, with loss of the ileocecal valve (ICV), is the most common anatomy in SBS, yet its impact on IFALD has not been adequately studied. Methods: Neonatal piglets were randomized to 75% intestinal resection with jejunocolic anastomosis (JC, n = 12), 75% resection with jejunoileal anastomosis and intact ICV (JI, n = 13), PN‐fed sham (sham, n = 14), or sow‐fed control (SF, n = 8). Surgical and sham piglets received 100% PN for 14 days before bile flow was measured and blood chemistry, liver pathology, jejunal permeability, and bacterial translocation were assessed. Results: Bile flow was lower for PN‐fed compared with SF (P = .002) but not different between the PN‐fed groups. Total bilirubin (P = .03) and liver pathology (P < .001) were greater in PN‐fed than SF groups but not different between PN‐fed groups. Serum bile acids were increased in sham (P = .01) but not different between SBS groups. PN‐fed piglets with sepsis had lower bile flow (P = .001) and increased bilirubin (P = .04). Neither jejunal permeability nor bacterial translocation were different between JC, JI, or sham groups. Conclusion: Contrary to our hypothesis, the remnant anatomy does not appear to worsen the progression of IFALD. However, the role of sepsis in IFALD should be further explored, in addition to other mechanisms, including PN factors, host immune responses, and intestinal bacterial dysbiosis.     

Responses of Preterm Pigs to an Oral Fluid Supplement During Parenteral Nutrition

Background: Nutrients and electrolytes in amniotic fluid swallowed by fetuses are important for growth and development. Yet, preterm infants requiring parenteral nutrition (PN) receive minimal or no oral inputs. With the limited availability of amniotic fluid, we evaluated the responses of preterm pigs receiving PN to an oral fluid supplement (OFS) based on the electrolyte and nutrient composition of amniotic fluid. Materials and Methods: Preterm pigs (92% of term) received a combination of PN (6 mL/kg‐h) and 4 mL/kg‐h of supplemental fluid as an experimental OFS (n = 9), lactated Ringer's either enterally (n = 10) or intravenously (n = 8). Outcome measures after 96 hours were weight gain, blood chemistry, organ weights, and small intestine mass and brush‐border membrane carbohydrases. Results: The OFS did not improve weight gain compared with providing lactated Ringer's orally or intravenously, or increase serum urea nitrogen values, but resulted in higher serum total and low‐density lipoprotein cholesterol, as well as improved glucoregulation and heavier intestines, livers, kidneys, and brains and lighter lungs. Conclusions: Providing supplemental fluid and electrolytes during PN either intravenously or orally increases weight gain after preterm birth. An oral fluid supplement based on amniotic fluid may accelerate development and maturation of organs critical for extrauterine life after preterm birth and may enhance neurodevelopment.     

Parenteral but Not Enteral Omega‐3 Fatty Acids (Omegaven) Modulate Intestinal Regrowth After Massive Small Bowel Resection in Rats

Background: The purpose of the present study was to evaluate the effects of ω‐3 fatty acids (Omegaven) on early intestinal adaptation in rats with short bowel syndrome (SBS). Methods: Male Sprague‐Dawley rats were randomly assigned to 1 of 4 groups: sham rats underwent bowel transection; SBS rats underwent 75% bowel resection; SBS‐O ω‐3 rats underwent bowel resection and were treated with oral Omegaven given by gavage; and SBS‐I ω‐3 rats underwent bowel resection and were treated with Omegaven given intraperitoneally. Rats were killed on day 14. Parameters of intestinal adaptation (bowel and mucosal weight, mucosal DNA and protein, villus height and crypt depths, cell proliferation and apoptosis) were determined at time of death. Real‐time polymerase chain reaction was used to determine the level of Bax and Bcl‐2 messenger RNA (mRNA). Statistical analysis was performed using Kruskal‐Wallis test followed by post hoc test, with P < .05 considered statistically significant. Results: Oral ω‐3 supplementation did not significantly change intestinal regrowth. In contrast, parenteral ω‐3 in rats that underwent resection resulted in higher bowel and mucosal weights, mucosal DNA and protein in ileum, villus height in ileum, crypt depth in jejunum and ileum, and greater rates of cell proliferation in jejunum and ileum compared with SBS animals. The initial decreased levels of apoptosis corresponded with the early decrease in Bax and increase in Bcl‐2 mRNA levels. Conclusions: Parenteral but not enteral Omegaven augments and accelerates structural bowel adaptation in a rat model of SBS. Increased cell proliferation and decreased apoptosis reflect increased cell turnover in Omegaven‐treated animals.     

Minimal Enteral Nutrition to Improve Adaptation After Intestinal Resection in Piglets and Infants

Background: Minimal enteral nutrition (MEN) may induce a diet‐dependent stimulation of gut adaptation following intestinal resection. Bovine colostrum is rich in growth factors, and we hypothesized that MEN with colostrum would stimulate intestinal adaptation, compared with formula, and would be well tolerated in patients with short bowel syndrome. Methods: In experiment 1, 3‐day‐old piglets with 50% distal small intestinal resection were fed parenteral nutrition (PN, n = 10) or PN plus MEN given as either colostrum (PN‐COL, n = 5) or formula (PN‐FORM, n = 9) for 7 days. Intestinal nutrient absorption and histomorphometry were performed. In experiment 2, tolerance and feasibility of colostrum supplementation were tested in a pilot study on 5 infants who had undergone intestinal resection, and they were compared with 5 resected infants who served as controls. Results: In experiment 1, relative wet‐weight absorption and intestinal villus height were higher in PN‐COL vs PN (53% vs 23% and 362 ± 13 vs 329 ± 7 µm, P < .05). Crypt depth and tissue protein synthesis were higher in PN‐COL (233 ± 7 µm, 22%/d) and PN‐FORM (262 ± 13 µm, 22%/d) vs PN (190 ± 4 µm, 9%/d, both P < .05). In experiment 2, enteral colostrum supplementation was well tolerated, and no infants developed clinical signs of cow’s milk allergy. Conclusion: Minimal enteral nutrition feeding with bovine colostrum and formula induced similar intestinal adaptation after resection in piglets. Colostrum was well tolerated by newly resected infants, but the clinical indication for colostrum supplementation to infants subjected to intestinal resection remains to be determined.