Crypt Cell Proliferation Rate Research Articles

The protective effects of hepatocyte growth factor on the intestinal mucosal atrophy induced by total parenteral nutrition in a rat model

PurposeTotal parental nutrition (TPN) causes gastrointestinal mucosal atrophy. The present study investigated the effects of hepatocyte growth factor (HGF) on the intestinal mucosal atrophy induced by TPN.MethodsRats underwent jugular vein catheterization and were divided into four groups: oral feeding (OF), TPN alone (TPN), TPN plus low-dose HGF (0.3 mg/kg/day; TPNLH), and TPN plus high-dose HGF (1.0 mg/kg/day; TPNHH). On day 7, rats were euthanized, and the small intestine was harvested and evaluated histologically. The expression of c-MET, a receptor of HGF, and nutrition transporter protein were evaluated using quantitative polymerase chain reaction.ResultsThe jejunal villus height (VH) and absorptive mucosal surface area in the TPNHH group were significantly higher than in the TPN group (p < 0.05). The VH in the ileum showed the same trend only in the TPNHH group, albeit without statistical significance. The crypt cell proliferation rate (CCPR) of the jejunum in both HGF-treated groups was significantly higher than in the TPN group (p < 0.01). The expression of c-MET and transporter protein in all TPN-treated groups was decreased compared with that in the OF group.ConclusionHGF attenuated TPN-associated intestinal mucosal atrophy by increasing the villus height, which was associated with an increase in CCPR.

Dose-response and functional role of whey permeate as a source of lactose and milk oligosaccharides on intestinal health and growth of nursery pigs.

Two experiments were conducted to evaluate dose-response and supplemental effects of whey permeate on growth performance and intestinal health of nursery pigs. In experiment (exp.) 1, 1,080 pigs weaned at 6.24 kg body weight (BW) were allotted to five treatments (eight pens/treatment) with increasing levels of whey permeate in three phases (from 10% to 30%, 3% to 23%, and 0% to 9% for phase 1, 2, and 3, respectively) fed until 11 kg BW and then fed a common phase 4 diet (0% whey permeate) until 25 kg BW in a 48-d feeding trial. Feed intake and BW were measured at the end of each phase. In exp. 2, 1,200 nursery pigs at 7.50 kg BW were allotted to six treatments (10 pens/treatment) with increasing levels of whey permeate from 0% to 18.75% fed until 11 kg BW. Feed intake and BW were measured during 11 d. Six pigs per treatment (1 per pens) were euthanized to collect the jejunum to evaluate tumor necrosis factor-alpha, interleukin-8 (IL-8), transforming growth factor-beta 1, mucin 2, histomorphology, digestive enzyme activity, crypt cell proliferation rate, and jejunal mucosa-associated microbiota. Data were analyzed using contrasts in the MIXED procedure and a broken-line analysis using the NLIN procedure of SAS. In exp. 1, increasing whey permeate had a quadratic effect (P < 0.05) on feed efficiency (G:F; maximum: 1.35 at 18.3%) in phase 1. Increasing whey permeate linearly increased (P < 0.05) average daily gain (ADG; 292 to 327 g/d) and G:F (0.96 to 1.04) of pigs in phase 2. In exp. 2, increasing whey permeate linearly increased (P < 0.05) ADG (349 to 414 g/d) and G:F (0.78 to 0.85) and linearly increased (P < 0.05) crypt cell proliferation rate (27.8% to 37.0%). The breakpoint from a broken-line analysis was obtained at 13.6% whey permeate for maximal G:F. Increasing whey permeate tended to change IL-8 (quadratic, P = 0.052; maximum: 223 pg/mg at 10.9%), to decrease Firmicutes:Bacteroidetes (P = 0.073, 1.59 to 1.13), to increase (P = 0.089) Bifidobacteriaceae (0.73% to 1.11%), and to decrease Enterobacteriaceae (P = 0.091, 1.04% to 0.52%) and Streptococcaceae (P = 0.094, 1.50% to 0.71%) in the jejunal mucosa. In conclusion, dietary inclusion of whey permeate increased the growth of nursery pigs from 7 to 11 kg BW. Pigs grew most efficiently with 13.6% whey permeate. Improvement in growth performance is partly attributed to stimulating intestinal immune response and enterocyte proliferation with positive changes in jejunal mucosa-associated microbiota in nursery pigs.

PSIV-22 Supplemental effects of dietary lysophospholipids in lactation diets on sow performance, milk composition, and intestinal health of piglets

Abstract Dietary lysophospholipids could enhance nutrient utilization through a structural change of enterocyte membrane with increasing permeability. The objective of this study was to determine supplemental effects of dietary lysophospholipids in lactation diets on sow performance, milk characteristics, and intestinal health of piglets. The 52 pregnant sows were allotted to 2 treatments in randomized complete block design with parity and BW as blocks at d 110 of pregnancy. The treatments were CON (no added lysophospholipids) and LPL (at 0.05% lysophospholipids; Lipidol-Ultra, Pathway Intermediates, Shrewsbury, UK). The lactation diets were formulated to meet or exceed nutrient requirements suggested by NRC (2012). Milk samples from 12 sows per treatment were collected to measure gross energy, protein, fat, fatty acid profile, and immunoglobulins (IgG and IgA) on d 1 and d 18 of lactation. Twelve piglets per treatment were euthanized on d 18 to collect tissues to measure tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), malondialdehyde, protein carbonyl, IgA, microbiota in jejunal and colonic mucosa, morphology and crypt cell proliferation rate in the jejunum. Data were analyzed using the MIXED procedure of SAS. Sows fed LPL tended to increase (P = 0.084) litter size (11.9 vs. 12.6) on d 18 of lactation and decrease (P = 0.079) ADFI (8.72 vs. 8.02 kg) during d 9 to d 18 of lactation. Sows fed LPL tended to increase (P = 0.092) IgG (1.14 vs. 1.94 g/L) in the milk. Sows fed LPL increased (P &amp;lt; 0.05) crypt cell proliferation rate (39.38 vs. 40.94%) in the jejunum. Supplementation of lysophospholipids in lactation diet did not affect proinflammatory cytokines, oxidative stress markers, and microbiota in jejunum and colon of piglets on d 18 of lactation. In conclusion, supplementation of dietary lysophopholipids improved productive performance and the intestinal cell proliferation of piglets with enhancing IgG concentration in the milk.

Supplemental effects of dietary lysophospholipids in lactation diets on sow performance, milk composition, gut health, and gut-associated microbiome of offspring

Dietary lysophospholipids (LPL) would influence milk composition of sows, thus positively affect intestinal health of offspring. The objective of this study was to determine effects of dietary LPL fed to lactating sows on performance, milk characteristics, gut health, and gut-associated microbiome of offspring. Sixty pregnant sows were allotted to 2 treatments in a randomized complete block design with parity and BW as blocks on day 110 of gestation. Treatments were CON (no added LPL) and LPL (0.05% LPL; Lipidol-Ultra, Pathway Intermediates, Shrewsbury, UK). Sows were fed 2 kg/d from day 110 of gestation until farrowing and ad libitum after farrowing. Diets were formulated to meet NRC requirement for lactating sows. Colostrum and milk samples from 12 sows per treatment were collected to measure nutrients and immunoglobulins on days 1 and 18 of lactation, respectively. Twelve piglets per treatment (1 piglet per litter) were euthanized on day 18 to collect tissues to measure tumor necrosis factor-α, interleukin-8 (IL-8), malondialdehyde, protein carbonyl, IgA, histomorphology, crypt cell proliferation rate, and microbiota in the jejunum and colon. Data were analyzed using the MIXED procedure of SAS, and the mortality was analyzed using the GLIMMIX procedure of SAS. There was no difference in sow BW, parity, and litter size between treatments on day 0 of lactation. Sows fed LPL had increased (P < 0.05) litter BW gain (53.9 vs. 59.4 kg) and decreased piglet mortality (13.9% vs. 10.6%) on day 18 of lactation. Sows fed LPL had increased (P < 0.05) omega-6:omega-3 (22.1 vs. 23.7) and unsaturated:saturated (1.4 vs. 1.6) fatty acids ratios with increased oleic acid (29.1% vs. 31.4%) and tended to have increased (P = 0.092) IgG (1.14 vs. 1.94 g/L) and linoleic acid (17.7% vs. 18.7%) in the milk on day 18 of lactation. Piglets from sows fed LPL had increased (P < 0.05) IL-8 (184 vs. 245 pg/mg) and crypt cell proliferation rate (39.4% vs. 40.9%) and tended to have increased (P = 0.095) Firmicutes:Bacteroidetes ratio (1.0 vs. 3.5) in the jejunum. In conclusion, sows fed with LPL had milk with increased IgG, oleic acids, and linoleic acids without changes in BW and backfat during lactation. These changes could contribute to improved survivability and intestinal health of piglets by increasing IL-8 concentration, enhancing balance among gut-associated microbiome, and increasing enterocyte proliferation in the jejunum.

Supplemental effects of dietary nucleotides on intestinal health and growth performance of newly weaned pigs.

Intestinal challenges upon weaning would increase the needs of nucleotides for enterocyte proliferation, whereas de novo synthesis maybe insufficient. This study aimed to evaluate supplemental effects of dietary nucleotides on intestinal health and growth performance in newly weaned pigs. Fifty newly weaned pigs (19-d-old, 25 barrows and 25 gilts, 4.76 ± 0.42 kg BW) were individually housed and allotted to 5 treatments with increasing nucleotide supplementation (0, 50, 150, 250, and 500 mg/kg) based on a randomized complete block design with the initial BW and sex as blocks. Dietary nucleotides were provided from YT500 (Hinabiotech, Guangzhou, China). Pigs were fed for 21 d based on 2 phases (phase 1: 11 d and phase 2: 10 d) and experimental diets were formulated to meet or exceed nutrient requirements suggested by NRC (2012). Feed intake and BW were recorded. Titanium oxide (0.4%) was added as an indigestible marker from day 17. Plasma collected on day 18 was used to measure tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and malondialdehyde (MDA). Pigs were euthanized on day 21 to collect tissues to evaluate TNF-α, IL-6, MDA, morphology, and crypt cell proliferation rate in the jejunum. Ileal digesta were collected to measure ileal nutrient digestibility. Data were analyzed using contrasts in the MIXED procedure of SAS. Nucleotide supplementation increased (P < 0.05) ADFI in phase 1. Nucleotide supplementation at 50 and 150 mg/kg increased (P < 0.05) ADG in phase 1, whereas increased (P < 0.05) ADFI and tended to increase (P = 0.082) ADG in overall. Increasing nucleotide supplementation changed (quadratic, P < 0.05) villus height-crypt ratio (at 247 mg/kg) and decreased (linear, P < 0.05) crypt cell proliferation rate in the jejunum. Increasing nucleotide supplementation reduced (P < 0.05) jejunal IL-6 (at 50 and 150 mg/kg) and tended to change (quadratic, P = 0.074) plasma MDA (at 231 mg/kg). Nucleotide supplementation at 50 and 150 mg/kg increased (P < 0.05) ileal digestibility of energy and ether extract. In conclusion, nucleotide supplementation at a range of 50 to 250 mg/kg in the diets seems to be beneficial to newly weaned pigs by enhancing growth performance possibly due to reduced intestinal inflammation and oxidative stress as well as improved intestinal villi structure and energy digestibility.

143 Supplemental effects of whey permeate on growth performance and gut health of nursery pigs

Abstract Lactose or milk oligosaccharides in milk products may enhance gut health and thus growth of nursery pigs. This study aimed to evaluate supplemental effects of increasing levels of whey permeate on growth performance and gut health in nursery pigs during 7 to 11 kg BW. 1,200 pigs at 7.5 kg BW were allotted to 6 treatments based on a randomized complete block design using BW of pen as blocks. Treatment diets were formulated to meet NRC nutrient requirements with 6 levels of whey permeate (0, 3.75, 7.50, 11.25, 15.00, and 18.75%) and fed to pigs for 11 d. Feed intake and BW were measured during 11 d, and 1 pig per pen were euthanized to collect the jejunum to evaluate TNF-α, IL-8, morphology, digestive enzyme activity, crypt cell proliferation rate, and microbiota. Data were analyzed using contrasts in the MIXED procedure and a broken-line analysis in NLIN procedure of SAS. Increasing whey permeate linearly increased (P &lt; 0.05) ADG (349 to 414 g/d) and G:F (0.783 to 0.851), tended to linearly increase (P = 0.062) ADFI (442 to 484 g/d), linearly increased (P &lt; 0.05) crypt cell proliferation rate (27.8 to 37.0%), linearly decreased (P &lt; 0.05) lactase activity (15.84 to 6.60 U/mg), and tended to linearly decrease (P = 0.082) crypt depth (268 to 251 μm). Using a broken line analysis, the optimum supplementation level of whey permeate was 13.60% for G:F. Supplementation of whey permeate increased (P &lt; 0.05) IL-8 (170 to 209 pg/mg) and decreased (P &lt; 0.05) Firmicutes to Bacteroidetes ratio (6.24 to 3.24) in the jejunum. In conclusion, supplementation of whey permeate enhanced growth performance and also positively affected gut health by modulating inflammatory response and microbiota in the jejunum of nursery pigs from 7 to 11 kg BW.

Maternal high-fat diet exposure during gestation, lactation, or gestation and lactation differentially affects intestinal morphology and proteome of neonatal mice

Offspring nutrition depends on the mother during gestation and lactation; thus, maternal nutrition and metabolism can affect their development. We hypothesized that maternal exposure to high-fat (HF) diet affects neonate's gastrointestinal tract development. Our objective was to determine the effect of maternal HF diet during gestation and lactation on neonate's duodenum histomorphology and proteome. Female mice were fed either a control (C, 10% kcal fat) or an HF (60% kcal fat) diet for 4 weeks and bred. On postnatal day 2, half the pups were cross-fostered to dams fed on different diet, creating 4 treatments: C-C, C-HF, HF-C, and HF-HF, indicating maternal diet during gestation-lactation, respectively. On postnatal day 12, pups' duodenum was excised and prepared for histology and liquid chromatography–tandem mass spectrometry analysis of proteome. Villi were significantly longer in HF-HF pups, and crypt cell proliferation rate was not different among treatments. Between C-C and HF-HF, HF-C, or C-HF, 812, 601, or 894 proteins were differentially expressed (Tukey adjusted P < .05), respectively. Functional analysis clustered proteins upregulated in HF-HF vs C-C in fat digestion and absorption, extracellular matrix, cell adhesion, immune response, oxidation-reduction processes, phagocytosis, and transport categories. Proteins downregulated were classified as RNA splicing, translation, protein folding, endocytosis, and transport. There was evidence for a carryover effect of exposure to HF diet during gestation to the postnatal period. Alterations in proteome relative to HF exposure potentially reflect long-term changes in the functioning of the duodenum.

CELF1/p53 axis: a sustained antiproliferative signal leading to villus atrophy under total parenteral nutrition.

Intestinal villus atrophy is a major complication of total parenteral nutrition (TPN). Our previous study revealed that TPN-induced villus atrophy is accompanied by elevated expression of CUGBP, Elav-like family member 1 (CELF1); however, its mechanism of action has not been fully understood. Herein, we report a pivotal role of CELF1/p53 axis, which induces a sustained antiproliferative signal, leading to suppressed proliferation of intestinal epithelial cells (IECs). By using a rat model of TPN, we found synchronous upregulation of CELF1 and p53 in jejunum mucosa, accompanied by a 51% decrease in crypt cell proliferation rate. By using HCT-116 cells as an IEC model in vitro, we found that the expression of CELF1 altered dynamically in parallel to proliferation rate, suggesting a self-adaptive expression pattern in IECs in vitro. Furthermore, ectopic overexpression of CELF1 elicited a significant antiproliferative effect in HCT-116, Caco-2, and IEC-6 cells, whereas knockdown of CELF1 elicited a significant proproliferative effect. Moreover, cell-cycle assay revealed that ectopic overexpression of CELF1 induced sustained G2 arrest and G1 arrest in HCT-116 and IEC-6 cells, respectively, which could be abolished by p53 silencing. Mechanistically, polysomal profiling and nascent protein analysis revealed that regulation of p53 by CELF1 was mediated through accelerating its protein translation in polysomes. Taken together, our findings revealed a sustained suppression of IEC proliferation evoked by CELF1/p53 axis, which may be a potential therapeutic target for the treatment of TPN-induced villus atrophy.-Yan, J.-K., Zhang, T., Dai, L.-N., Gu, B.-L., Zhu, J., Yan, W.-H., Cai, W., Wang, Y. CELF1/p53 axis: a sustained antiproliferative signal leading to villus atrophy under total parenteral nutrition.

The effect of intravenous lipid emulsions and mucosal adaptation following massive bowel resection

Aims and objectivesFish oil (FO) lipid emulsion and a new lipid emulsion (SMOF) are important treatments for intestinal failure-associated liver disease. We evaluated the efficacy of FO and SMOF lipid emulsion on intestinal mucosal adaptation using a total parenteral nutrition (TPN)-supported rat model of short bowel syndrome. Material & methodsSprague–Dawley rats underwent jugular vein catheterization and 90% small bowel resection and were divided into three groups: TPN with soy bean oil lipid emulsion (SO group), FO lipid emulsion (FO group), or SMOF (SMOF group). On day 13, the rats were euthanized, and the small intestine was harvested. The microscopic morphology and crypt cell proliferation rate (CCPR) were then evaluated. ResultsThe villus height of the ileum in the SMOF group was significantly higher than in the SO group. The crypt depth of the intestine in the SMOF group was significantly lower than in the SO group. The CCPRs of the intestine in the FO and SMOF groups were both higher than in the SO group. ConclusionsLipid emulsion affected the bowel morphology, such as the mucosa as well as the intestinal smooth muscle. Further studies are needed to clarify the mechanisms.

Ghrelin stimulates intestinal adaptation following massive small bowel resection in parenterally fed rats

BackgroundSince short bowel syndrome (SBS) patients face life-threatening conditions, the development of therapeutic strategies to induce intestinal adaptation has been investigated. Ghrelin, a ligand of growth hormone (GH) secretagogue-receptor that stimulates the release of GH and insulin like growth factor-1 (IGF-1), has several pleiotropic effects. We investigated whether ghrelin induces intestinal adaptation in parenterally fed rats with SBS. MethodsSprague-Dawley rats underwent venous catheterization and were divided into 3 groups: those receiving 90% small bowel resection while leaving the proximal jejunum and distal ileum (90% SBR) with TPN (SBS/TPN group), those receiving 90% SBR with TPN + ghrelin (SBS/TPN/ghrelin group), and those receiving sham operation and fed chow (sham group). Ghrelin was administered intravenously at 10 μg/kg/day. On Day 13, the rats were euthanized and the small intestine harvested, and the histology and crypt cell proliferation rates (CCPR), apoptosis, and nutrient transporter protein levels were analyzed and the plasma hormones were measured. ResultsThe villus height and crypt depth of the ileum in the SBS/TPN/ghrelin group were significantly higher than in the SBS/TPN group. The CCPR of the jejunum and the ileum significantly increased by the administration of ghrelin; however, the apoptosis rates did not significantly differ between the SBS/TPN and SBS/TPN/ghrelin groups. Significant differences did not exist in the plasma IGF-1 and nutrient transporter protein levels among three groups. ConclusionsThe intravenous administration of ghrelin stimulated the morphological intestinal adaptation of the ileum to a greater degree than the jejunum due to the direct effect of ghrelin.

Effects of chronic glucagon-like peptide-2 therapy during weaning in neonatal pigs

BackgroundThe enteroendocrine hormone glucagon like peptide-2 (GLP-2) and its ligands are under development as therapeutic agents for a variety of intestinal pathologies. A number of these conditions occur in neonates and infants, and thus a detailed understanding of the effects of GLP-2 during the phase of rapid growth during infancy is required to guide the development of therapeutic applications. We studied the effects of GLP-2 in the neonatal pig to determine the potential effects of exogenous administration. MethodsTwo day old newborn domestic piglets were treated with GLP-2 (1–33) at 40μg/kg/day or control drug vehicle (saline), by subcutaneous injection, given in two doses per day, (n=6/group) for 42days. Animals were weaned normally, over days 21–25. In the fifth week of life, they underwent neuro-developmental testing, and a pharmacokinetic study. On day 42, they were euthanized, and a complete necropsy performed, with histological assessment of tissues from all major organs. ResultsGLP-2 treatment was well tolerated, one control animal died from unrelated causes. There were no effects of GLP-2 on weight gain, feed intake, or behavior. In the treated animals, GLP-2 levels were significantly elevated at 2400±600pM while at necropsy, organ weights and histology were not affected except in the intestine, where the villus height in the small intestine and the crypt depth, throughout the small intestine and colon, were increased. Similarly, the rate of crypt cell proliferation (Ki-67 staining) was increased in the GLP-2 treated animals and the rate of apoptosis (Caspase-3) was decreased, the depth of the microvilli was increased and the expression of the mRNA for the GLP-2 receptor was decreased throughout the small and large intestine. ConclusionsIn these growing animals, exogenous GLP-2 at pharmacologic doses was well tolerated, with effects confined to the gastrointestinal tract.

Wnt Ligand Expression and Regulation of Stem Cells During Postnatal Growth of the Small Intestine in Rats

Background: The sequential proliferation, lineage-specific differentiation, crypt-villus migration, and cell death of the epithelial cells of the intestinal mucosa is tightly regulated by regulatory peptides, differentiation signals, and luminal stimuli, including nutrients and pathogenic/commensal organisms. Despite its importance for understanding normal homeostasis and pathogenesis of disease states, the intracellular signal transduction mechanisms involved remain incompletely understood. Here, we tested the hypothesis that PKD1 plays a key role in intestinal crypt cell proliferation In Vivo. Results: To clarify the role of PKD1 in intestinal epithelial cell proliferation In Vivo, we generated transgenic mice that express elevated PKD1 protein in the distal small intestinal and proximal colonic epithelium. The catalytic activity and multi-site phosphorylation (Ser744, Ser748 and Ser916) of PKD1 was strikingly higher in extracts from ileal mucosa of transgenic mice as compared with non-transgenic littermates. These results indicate that transgenic PKD1 is functional in the intestinal epithelium. PKD1 signaling stimulated intestinal cell proliferation, as shown by detection of 5-bromo-2-deoxyuridine (BrdU) incorporated into the cell nuclei of crypt cells of the ileum and proximal colon, where PKD1 protein is maximally expressed. Our results demonstrated a highly statistically significant increase (p<0.005) in DNA synthesizing cells in the crypts of the PKD1 transgenic mice as compared with non-transgenic littermates. In the intestine, normal cell numbers are maintained by balancing rates of cell proliferation, differentiation, migration and apoptosis. Consequently, we determined whether transgenic PKD1 leads to a change in tissue architecture, manifested by an increase in the size and total number of epithelial cells in the crypts. We measured crypt height (in micrometer and cell number) and crypt circumference (in micrometer and cell number) in histological sections of control and PKD1 transgenic mice. The data was used to calculate the size of individual cells and the total number of cells per crypt. Our results show a significant increase in the depth (either in μm or in number of cells) and in the total number of cells per crypt in the transgenic PKD1 mice as compared with the nontransgenic littermates (276 total cells per ileal crypt in transgenic mice versus 192 in nontransgenic mice; p< 0.005). These results indicate that the expression of the PKD1 transgene led to a marked increase (44%) in the total number of intestinal epithelial cells per crypt. Conclusion: Transgenic PKD1 expression increases the number of cells per crypt by stimulating the rate of crypt cell proliferation. These results support the hypothesis that PKD1 signaling plays a role in a pathway leading to proliferation in intestinal epithelial cells.

Protein Kinase D1 Mediates Stimulation of DNA Synthesis and Proliferation in Intestinal Epithelial IEC-18 Cells and in Mouse Intestinal Crypts

We examined whether protein kinase D1 (PKD1), the founding member of a new protein kinase family, plays a critical role in intestinal epithelial cell proliferation. Our results demonstrate that PKD1 activation is sustained, whereas that of PKD2 is transient in intestinal epithelial IEC-18 stimulated with the G(q)-coupled receptor agonists angiotensin II or vasopressin. PKD1 gene silencing utilizing small interfering RNAs dramatically reduced DNA synthesis and cell proliferation in IEC-18 cells stimulated with G(q)-coupled receptor agonists. To clarify the role of PKD1 in intestinal epithelial cell proliferation in vivo, we generated transgenic mice that express elevated PKD1 protein in the intestinal epithelium. Transgenic PKD1 exhibited constitutive catalytic activity and phosphorylation at the activation loop residues Ser(744) and Ser(748) and on the autophosphorylation site, Ser(916). To examine whether PKD1 expression stimulates intestinal cell proliferation, we determined the rate of crypt cell DNA synthesis by detection of 5-bromo-2-deoxyuridine incorporated into the nuclei of crypt cells of the ileum. Our results demonstrate a significant increase (p < 0.005) in DNA-synthesizing cells in the crypts of two independent lines of PKD1 transgenic mice as compared with non-transgenic littermates. Morphometric analysis showed a significant increase in the length and in the total number of cells per crypt in the transgenic PKD1 mice as compared with the non-transgenic littermates (p < 0.01). Thus, transgenic PKD1 signaling increases the number of cells per crypt by stimulating the rate of crypt cell proliferation. Collectively, our results indicate that PKD1 plays a role in promoting cell proliferation in intestinal epithelial cells both in vitro and in vivo.

Deletion of Tis7 Protects Mice from High-Fat Diet-Induced Weight Gain and Blunts the Intestinal Adaptive Response Postresection1–3

After loss of intestinal surface area, the remaining bowel undergoes a morphometric and functional adaptive response. Enterocytic expression of the transcriptional coregulator tetradecanoyl phorbol acetate induced sequence 7 (Tis7) is markedly increased in a murine model of intestinal adaptation. Mice overexpressing Tis7 in intestine have greater triglyceride absorption and weight gain when fed a high-fat diet (42% energy) than their wild-type (WT) littermates fed the same diet. These and other data suggest that Tis7 has a unique role in nutrient absorptive and metabolic adaptation. Herein, male Tis7−/− and WT mice were fed a high-fat diet (42% energy) for 8 wk. Weight was monitored and metabolic analyses and hepatic and intestinal lipid concentrations were compared after 8 wk. Intestinal lipid absorption and metabolism studies and intestinal resection surgeries were performed in separate groups of Tis7−/− and WT mice. At 8 wk, weight gain was less and jejunal mucosal and hepatic triglyceride and cholesterol concentrations were lower in Tis7−/− mice than in the WT controls. Following corn oil gavage, serum cholesterol, triglyceride, and FFA concentrations were lower in the Tis7−/− mice than in the WT mice. Incorporation of oral 3[H] triolein into intestinal mucosal cholesterol ester and FFA was less in Tis7−/− compared with WT mice. Following resection, crypt cell proliferation rates and villus heights were lower in Tis7−/− than in WT mice, indicating a blunted adaptive response. Our results suggest a novel physiologic function for Tis7 in the gut as a global regulator of lipid absorption and metabolism and epithelial cell proliferation.

Effect of Fat Supplementation on the Maintenance of Gut Integrity in Elemental Diet-Fed Rats

The aims of this study were to investigate the mechanism of atrophic change in ileal mucosa supplied with an elemental diet (ED) and to assess the value of supplemented fat emulsion in the prevention of atrophic change. In experiment 1, 25 male Wistar rats with a body weight of 160-180 g were divided into 3 groups. The first group was fed regular rat chow (Control group, n=5). The second group was given ED containing 0.6% long-chain triglycerides (ED group, n=10). The third group was provided with fat-enriched ED (FED) containing 3.5% long-chain triglycerides (FED group, n=10). Each group received an isocaloric diet (300 kcal/kg/day). 4 weeks later, after euthanization, ileal samples were taken for light and electron microscopic examinations. The morphological changes of the intestinal mucosa and the crypt cell proliferation rate (CCPR) were determined. In experiment 2, to determine the site of fat absorption, 9 rats were fed ED for 1 week. After 24 h of food deprivation, all rats were given 2 ml of FED through a gastric tube. Then 1, 2, and 3 h(s) later, groups of 3 rats each were euthanized, and the total small intestine was obtained from each rat. The proximal and distal jejunum and distal ileum were stained with oil red O. In experiment 1, the samples had almost the same morphological appearance irrespective of the type of feeding. The CCPR was significantly diminished in the ED group compared with the Control group, while there was no statistical difference between the FED and Control groups. In experiment 2, the oil red O stain was positive in the proximal and distal jejunum, but was completely negative in the distal ileum. The introduction of ED does not soon result in an atrophic morphological change of the ileum but will decrease the CCPR. An additive fat emulsion which was rapidly absorbed by the distal jejunum could play a role in maintaining ileal mucosa integrity through some mechanism independent of absorption.

The influence of nutrients, biliary-pancreatic secretions, and systemic trophic hormones on intestinal adaptation in a Roux-en-Y bypass model

Purpose The signals that govern the upregulation of nutrient absorption (adaptation) after intestinal resection are not well understood. A Gastric Roux-en-Y bypass (GRYB) model was used to isolate the relative contributions of direct mucosal stimulation by nutrients, biliary-pancreatic secretions, and systemic enteric hormones on intestinal adaptation in short bowel syndrome. Methods Male rats (350-400 g; n = 8/group) underwent sham or GRYB with pair feeding and were observed for 14 days. Weight and serum hormonal levels (glucagon-like peptide-2 [GLP-2], PYY) were quantified. Adaptation was assessed by intestinal morphology and crypt cell kinetics in each intestinal limb of the bypass and the equivalent points in the sham intestine. Mucosal growth factors and expression of transporter proteins were measured in each limb of the model. Results The GRYB animals lost weight compared to controls and exhibited significant adaptive changes with increased bowel width, villus height, crypt depth, and proliferation indices in the alimentary and common intestinal limbs. Although the biliary limb did not adapt at the mucosa, it did show an increased bowel width and crypt cell proliferation rate. The bypass animals had elevated levels of systemic PYY and GLP-2. At the mucosal level, insulin-like growth factor-1 (IGF-1) and basic fibroblast growth factor (bFGF) increased in all limbs of the bypass animals, whereas keratinocyte growth factor (KGF) and epidermal growth factor (EGF) had variable responses. The expression of the passive transporter of glucose, GLUT-2, expression was increased, whereas GLUT-5 was unchanged in all limbs of the bypass groups. Expression of the active mucosal transporter of glucose, SGLT-1 was decreased in the alimentary limb. Conclusions Adaptation occurred maximally in intestinal segments stimulated by nutrients. Partial adaptation in the biliary limb may reflect the effects of systemic hormones. Mucosal content of IGF-1, bFGF, and EGF appear to be stimulated by systemic hormones, potentially GLP-2, whereas KGF may be locally regulated. Further studies to examine the relationships between the factors controlling nutrient-induced adaptation are suggested. Direct contact with nutrients appears to be the most potent factor in inducing mucosal adaptation.

751 Transgenic Protein Kinase D1 Stimulates the Rate of Epithelial Cell Proliferation in Intestinal Crypts

Background: The sequential proliferation, lineage-specific differentiation, crypt-villus migration, and cell death of the epithelial cells of the intestinal mucosa is tightly regulated by regulatory peptides, differentiation signals, and luminal stimuli, including nutrients and pathogenic/commensal organisms. Despite its importance for understanding normal homeostasis and pathogenesis of disease states, the intracellular signal transduction mechanisms involved remain incompletely understood. Here, we tested the hypothesis that PKD1 plays a key role in intestinal crypt cell proliferation In Vivo. Results: To clarify the role of PKD1 in intestinal epithelial cell proliferation In Vivo, we generated transgenic mice that express elevated PKD1 protein in the distal small intestinal and proximal colonic epithelium. The catalytic activity and multi-site phosphorylation (Ser744, Ser748 and Ser916) of PKD1 was strikingly higher in extracts from ileal mucosa of transgenic mice as compared with non-transgenic littermates. These results indicate that transgenic PKD1 is functional in the intestinal epithelium. PKD1 signaling stimulated intestinal cell proliferation, as shown by detection of 5-bromo-2-deoxyuridine (BrdU) incorporated into the cell nuclei of crypt cells of the ileum and proximal colon, where PKD1 protein is maximally expressed. Our results demonstrated a highly statistically significant increase (p<0.005) in DNA synthesizing cells in the crypts of the PKD1 transgenic mice as compared with non-transgenic littermates. In the intestine, normal cell numbers are maintained by balancing rates of cell proliferation, differentiation, migration and apoptosis. Consequently, we determined whether transgenic PKD1 leads to a change in tissue architecture, manifested by an increase in the size and total number of epithelial cells in the crypts. We measured crypt height (in micrometer and cell number) and crypt circumference (in micrometer and cell number) in histological sections of control and PKD1 transgenic mice. The data was used to calculate the size of individual cells and the total number of cells per crypt. Our results show a significant increase in the depth (either in μm or in number of cells) and in the total number of cells per crypt in the transgenic PKD1 mice as compared with the nontransgenic littermates (276 total cells per ileal crypt in transgenic mice versus 192 in nontransgenic mice; p< 0.005). These results indicate that the expression of the PKD1 transgene led to a marked increase (44%) in the total number of intestinal epithelial cells per crypt. Conclusion: Transgenic PKD1 expression increases the number of cells per crypt by stimulating the rate of crypt cell proliferation. These results support the hypothesis that PKD1 signaling plays a role in a pathway leading to proliferation in intestinal epithelial cells.

Nutritional effects of the serial transverse enteroplasty procedure in experimental short bowel syndrome

Background/Purpose The serial transverse enteroplasty (STEP) procedure appears beneficial clinically, but the mechanism(s) underlying these effects remains unclear. The present study evaluated the nutritional, hormonal, and morphologic effects of the STEP procedure in a rodent model of short bowel syndrome. Methods With institutional animal care ethics approval, Sprague-Dawley rats underwent an 80% distal bowel resection, anastomosing the 30 cm remnant of jejunum to the ascending colon; at day 14, animals were randomly assigned to control or a STEP procedure (n = 8/group). Animals were pair-fed with normal chow; after a further 3 weeks, intestinal transit, hormonal and metabolic balance studies were done, and intestinal tissues were taken for analysis. Results The STEP group had increased weight gain (resected: −0.34% ± 2.9% vs STEP: 2.5% ± 1.5%), increased bowel length (34.1 ± 1.5 vs 36.9 ± 2.2 cm), increased jejunal villus height (555 ± 59 vs 635 ± 65 μm), decreased rates of crypt cell apoptosis, increased expression of mRNA for the GLP-2 receptor, and increased postprandial production of glucagon-like peptide 2 (45 ± 14 vs 65 ± 12 pmol/L) ( P < .05 by Student t test). There were no differences in intestinal transit; absorption of total calories, protein, fat, or carbohydrate; crypt cell proliferation rates; or the expression of intestinal transporter proteins (SGLT-1, GLUT-2, and GLUT-5). Conclusions The STEP procedure improves weight gain and augments gross and microscopic intestinal morphology in severe experimental short bowel syndrome. Postprandial GLP-2 levels are increased, as is the expression of the GLP-2 receptor; these mechanisms may contribute to these metabolic effects and may be useful in guiding the use of the STEP procedure clinically.

Interleukin-6 is an important in vivo inhibitor of intestinal epithelial cell death in mice

Background and aimsInterleukin-6 (IL-6) is a well-recognised mediator of liver disease and regeneration. However, the in vivo effects of IL-6 on enterocytes and the intestinal tract have not been elucidated....

Why do African Americans get more colon cancer than Native Africans?

The incidence of colorectal cancer (CRC) is dramatically higher in African Americans (AAs) than in Native Africans (NAs) (60:100,000 vs. <1:100,000) and slightly higher than in Caucasian Americans (CAs). To explore whether the difference could be explained by interactions between diet and colonic bacterial flora, we compared randomly selected samples of healthy 50- to 65-y-old AAs (n = 17) with NAs (n = 18) and CAs (n = 17). Diet was measured by 3-d recall, and colonic metabolism by breath hydrogen and methane responses to oral lactulose. Fecal samples were cultured for 7-alpha dehydroxylating bacteria and Lactobacillus plantarum. Colonoscopic mucosal biopsies were taken to measure proliferation rates. In comparison with NAs, AAs consumed more (P < 0.01) protein (94 +/- 9.3 vs. 58 +/- 4.1 g/d) and fat (114 +/- 11.2 vs. 38 +/- 3.0 g/d), meat, saturated fat, and cholesterol. However, they also consumed more (P < 0.05) calcium, vitamin A, and vitamin C, and fiber intake was the same. Breath hydrogen was higher (P < 0.0001) and methane lower in AAs, and fecal colony counts of 7-alpha dehydroxylating bacteria were higher and of Lactobacilli were lower. Colonic crypt cell proliferation rates were dramatically higher in AAs (21.8 +/- 1.1% vs. 3.2 +/- 0.8% labeling, P < 0.0001). In conclusion, the higher CRC risk and mucosal proliferation rates in AAs than in NAs were associated with higher dietary intakes of animal products and higher colonic populations of potentially toxic hydrogen and secondary bile-salt-producing bacteria. This supports our hypothesis that CRC risk is determined by interactions between the external (dietary) and internal (bacterial) environments.