Effect of growth hormone, epidermal growth factor, and insulin on bacterial translocation in experimental short bowel syndrome

The ileum positively regulates hepatic regeneration in rats

PURPOSE

To test the hypothesis that liver regeneration after partial hepatectomy can be influenced by the ileum.

METHODS

Eighteen Wistar rats were distributed into groups of six animals: 1 - ileum resection+ hepatectomy 2/3; 2 - hepatectomy 2/3, and 3 - sham. Anesthesia with ketamine and xylazine i.p., aseptic technique, analgesia with meperidine (10mg/kg s.c.). On day 6, serum ALT, AST, alkaline phosphatase (AP) and albumin were measured. Liver regeneration and hepatocyte mitosis were quantified. Statistical analysis with ANOVA and Tukey tests, with significance p<0.05.

RESULTS

In group hepatectomy+ileal resection, ALT, AST and AP were 180.6±24.9, 58.6±3.1 and 254.6±46.6 respectively. They were significantly higher than in the hepatectomy group, whose values were 126.0±16.5, 44.1±3.9 and 163.5±8.6, respectively (p<0.001). Albumin levels were not significantly different among groups. Liver regeneration in hepatectomy group (94.17%) was statistically higher (p<0.001) than in ileal resection+hepatectomy group (55.96%). In the latter group the mitosis of hepatocytes were significantly less frequent than in the hepatectomy group.

CONCLUSION

The data confirm that the ileum positively influence on liver regeneration in rats undergoing hepatectomy.

ErbB receptors and their growth factor ligands in pediatric intestinal inflammation

The ErbB tyrosine kinases (epidermal growth factor receptor (EGFR), ErbB2/HER2, ErbB3, and ErbB4) are cell surface growth factor receptors widely expressed in many developing mammalian tissues, including in the intestinal tract. Signaling elicited by these receptors promotes epithelial cell growth and survival, and ErbB ligands have been proposed as therapeutic agents for intestinal diseases of pediatric populations, including inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and inflammation associated with total parenteral nutrition (TPN). Furthermore, emerging evidence points to reduced ErbB ligand expression and thus reduced ErbB activity in IBD, NEC, and TPN models. This review will discuss the current understanding of the role of ErbB receptors in the pathogenesis and potential treatment of pediatric intestinal inflammation, with focus on the altered signaling in disease and the molecular mechanisms by which exogenous ligands are protective.

Gastric pentadecapeptide BPC 157 and short bowel syndrome in rats

The gastric pentadecapeptide BPC 157, which was shown to be safe as an antiulcer peptide in trials for inflammatory bowel disease (PL14736, Pliva), successfully healed intestinal anastomosis and fistula in rat. Therefore, we studied for 4 weeks rats with escalating short bowel syndrome and progressive weight loss after small bowel resection from fourth ileal artery cranially of ileocecal valve to 5 cm beneath pylorus. BPC 157 (10 microg/kg or 10 ng/kg) was given perorally, in drinking water (12 ml/rat/day) or intraperitoneally (once daily, first application 30 min following surgery, last 24 h before sacrifice). Postoperatively, features of increasingly exhausted presentation were: weight loss appearing immediately regardless of villus height, twofold increase in crypt depth and fourfold increase in muscle thickness within the first week, jejunal and ileal overdilation, and disturbed jejunum/ileum relation. In contrast, constant weight gain above preoperative values was observed immediately with BPC 157 therapy, both perorally and parenterally, and villus height, crypt depth, and muscle thickness [inner (circular) muscular layer] also increased, at 7, 14, 21, and 28 days. Moreover, rats treated with pentadecapeptide BPC 157 showed not different jejunal and ileal diameters, constant jejunum-to-ileum ratio, and increased anastomosis breaking strength. In conclusion, pentadecapeptide BPC 157 could be helpful to cure short bowel syndrome.

Effects of recombinant human growth hormone on enterocutaneous fistula patients

AIM: To explore the effects of recombinant human growth hormone (rhGH) on intestinal mucosal epithelial cell proliferation and nutritional status in patients with enterocutaneous fistula.

METHODS: Eight patients with enterocutaneous fistulas received recombinant human growth hormone (10 μg/d) for 7 d. Image analysis and immunohisto-chemical techniques were used to analyse the expression of proliferating cell nuclear antigen (PCNA) in intestinal mucosal epithelial cells in biopsy samples from the patients who had undergone an endoscopic biopsy through the fistula at day 0, 4 and 7. Body weights, nitrogen excretion, serum levels of total proteins, albumin, prealbumin, transferrin and fibronectin were measured at day 0, 4 and 7.

RESULTS: Significant improvements occurred in the expression of PCNA in the intestinal mucosal epithelial cells at day 4 and 7 compared to day 0 (24.93 ± 3.41%, 30.46 ± 5.24% vs 12.92 ± 4.20%, P < 0.01). These changes were accompanied by the significant improvement of villus height (500.54 ± 53.79 μm, 459.03 ± 88.98 μm vs 210.94 ± 49.16 μm, P < 0.01), serum levels of total proteins (70.52 ± 5.13 g/L, 74.89 ± 5.16 g/L vs 63.51 ± 2.47 g/L, P < 0.01), albumin (39.44 ± 1.18 g/L, 42.39 ± 1.68 g/L vs 35.74 ± 1.75 g/L, P < 0.01) and fibronectin (236.3 ± 16.5 mg/L, 275.8 ± 16.9 mg/L vs 172.5 ± 21.4 mg/L, P < 0.01) at day 4 and 7, and prealbumin (286.38 ± 65.61 mg/L vs 180.88 ± 48.28 mg/L, P < 0.05), transferrin (2.61 ± 0.12 g/L vs 2.41 ± 0.14 g/L, P < 0.05) at day 7. Nitrogen excretion was significantly decreased at day 7 (3.40 ± 1.65 g/d vs 7.25 ± 3.92 g/d, P < 0.05). No change was observed in the body weight.

CONCLUSION: Recombinant human growth hormone could promote intestinal mucosal epithelial cell proliferation and protein synthesis in patients with enterocutaneous fistula.

Mucin Gene Expression and Mucin Content in the Chicken Intestinal Goblet Cells Are Affected by In Ovo Feeding of Carbohydrates

The protective mucus layer covers the entire surface of the gastrointestinal tract. The mucus layer also acts as a medium for molecule transport between the luminal contents and the enterocytes; therefore it has a major role in nutrient absorption. The main mucus layer component, mucin glycoproteins, is produced by mucous-secreting goblet cells. In chicken small intestine, functional development of goblet cells and enterocytes occurs in the late embryonic and immediate posthatch period. Presence of the nutrient is crucial for mucosal development. Feed deprivation immediately after hatch caused delayed mucosa development and perturbed mucin dynamics. Recent studies showed the intraamnionic nutrient supply (in-ovo feeding; IOF) accelerated mucosa functional development. In this study, the effect of IOF on the mucin mRNA expression and mucin content in the goblet cells was studied. The feeding solution containing carbohydrates was administered to the amnionic fluid of the Cobb embryos at d 17.5 of incubation. Samples from the jejunum were taken at d 17 of incubation (before IOF), and then 10 embryos from each group were sampled at 19 d of incubation, at hatch, and at d 3 posthatch. Following IOF, villus surface area increased at day of hatch and 3 d posthatch by 27 and 21%, respectively. In addition, the proportion of goblet cells containing acidic mucin increased 36 h after injection by 50% compared with the controls. The mucin mRNA expression increased gradually from d 17 of incubation to 3 d posthatch. Enhanced expression of the mucin mRNA was found at the day of hatch in chicks that received carbohydrate solution into the amnionic fluid in comparison with the control group. The results showed that providing the carbohydrates as an energy source to the late-term embryo had a trophic effect on the small intestine and enhanced goblet cell development.

Epidermal growth factor and bombesin act synergistically to support intestinal adaptation in rats with massive small bowel resection

Intestinal adaptation is the most important event in short bowel syndrome following a massive small bowel resection. Effects of various growth factors and their synergism have been well documented in intestinal adaptation. This study aimed to compare the effect of two different trophic agents, epidermal growth factor (EGF) and bombesin (BBS), on intestinal adaptation following massive intestinal resection. Sprague-Dawley male rats were assigned to one of four groups after a 75% small bowel resection. Either EGF (90 microg/kg), BBS (10 microg/kg), EGF+BBS, or bovine serum albumin (BSA) were injected subcutaneously three times a day. The animals were killed 10 days after the operation. Weight loss and morphologic parameters such as mucosal thickness, villus height, crypt depth, villus-to-crypt ratio, and muscularis propria height were measured. In the EGF+BBS group, mucosal thickness was found to be significantly increased compared with the other study groups (p<0.05). Similarly, villus height was significantly increased only in the EGF+BBS group (p<0.05). In the BBS group, both villus height and mucosal thickness showed a slight increase, but the values were not statistically significant compared with the vehicle-treated group. There were no significant differences in any of the remaining parameters between the groups. The results of this study indicate that the gut hormones EGF and BBS act synergistically in facilitating the adaptive response of the remnant ileum to massive intestinal resection.

A simple method of intestinal anastomosis (ileocolostomy) in rats

A simple method of ileocolostomy was performed in rats. The colon near the cecum was ligated, including its arteries and veins. Main artery and vein of the cecum were ligated. Then, the cecum was cut out. A longitudinal incision was made on the anti-mesenteric side of the proximal end of the colon, approximately 7-8 mm long. A 21-G needle was inserted toward the incision 2 cm away from the proximal end of the anti-mesenteric side of the colon. A nylon suture was knotted once to the distal end of the ileum and was introduced into the tip of the needle which had previously been passed through the colon. Then, the needle was removed. The suture was pulled to introduce the distal end of the ileum into the colonic lumen. Then, the suture was knotted once on the colon again to fix the ileum to the colon. The incision in the proximal end of the colon was not closed. At the 2nd week after the operation, X-ray examinations demonstrated that the ileocolonic passages with no leakage at the anastomotic site were quite satisfactory. At the 4th week after the operation, there were no macroscopic or microscopic complications at the anastomotic site. The mucosal and serosal epithelia of the ileum and colon continued smoothly. This simple method may be very effective in preparing anastomosis in the gastrointestinal tract, especially in small laboratory animals for nutritional and surgical experiments.

Comparative effects of glucagon-like peptide-2 (GLP-2), growth hormone (GH), and keratinocyte growth factor (KGF) on markers of gut adaptation after massive small bowel resection in rats

BACKGROUND

Administration of specific growth factors exert gut-trophic effects in animal models of massive small bowel resection (SBR); however, little comparative data are available. Our aim was to compare effects of a human glucagon-like peptide-2 (GLP-2) analog, recombinant growth hormone (GH) and recombinant keratinocyte growth factor (KGF) on jejunal, ileal, and colonic growth and functional indices after 80% SBR in rats.

METHODS

Thirty-seven male rats underwent small bowel transection (sham operation) with s.c. saline administration (control; Tx-S; n = 7) or 80% midjejuno-ileal resection (Rx) and treatment with either s.c. saline (Rx-S, n = 7), GLP-2 at 0.2 mg/kg/d (Rx-GLP-2; n = 8), GH at 3.0 mg/kg/d (Rx-GH; n = 8), or KGF at 3.0 mg/kg/d (Rx-KGF; n = 7) for 7 days. All groups were pair-fed to intake of Rx-S rats. Gut mucosal cell growth indices (wet weight, DNA and protein content, villus height, crypt depth, and total mucosal height) were measured. Expression of the cytoprotective trefoil peptide TFF3 was determined by Western blot. Gut mucosal concentrations of the tripeptide glutathione (L-glutamyl-L-cysteinyl-glycine) and glutathione disulfide (GSSG) were measured by high-performance liquid chromatography and the glutathione/GSSG ratio calculated.

RESULTS

SBR increased adaptive growth indices in jejunal, ileal, and colonic mucosa. GLP-2 treatment increased jejunal villus height and jejunal total mucosal height compared with effects of resection alone or resection with GH or KGF treatment. Both GH and KGF modestly increased colonic crypt depth after SBR. SBR did not affect small bowel or colonic goblet cell number or TFF3 expression; however, goblet cell number and TFF3 expression in both small bowel and colon were markedly up-regulated by KGF treatment and unaffected by GLP-2 and GH. SBR oxidized the ileal and colonic mucosal glutathione/GSSG redox pools. GLP-2 treatment after SBR increased the glutathione/GSSG ratio in jejunum, whereas KGF had an intermediate effect. In addition, GLP-2 (but not GH or KGF) prevented the SBR-induced oxidation of the glutathione/GSSG pools in both ileum and colon.

CONCLUSIONS

GLP-2 exerts superior trophic effects on jejunal growth and also improves mucosal glutathione redox status throughout the bowel after massive SBR in rats. Both GH and KGF increase colonic mucosal growth in this model. KGF alone potently increases gut mucosal goblet cell number and expression of the cytoprotective trefoil peptide TFF3. The differential effects of GLP-2, GH and KGF administration in this model of short bowel syndrome suggest that individual therapy with these growth factors may not be an adequate strategy to maximally improve adaptive gut mucosal growth and cytoprotection after massive small intestinal resection. Future research should address the use of these agents in combination in short bowel syndrome.

Epidermal growth factor and interleukin-1beta synergistically stimulate the production of nitric oxide in rat intestinal epithelial cells

Epidermal growth factor (EGF) is one of the trophic factors for intestinal adaptation after small bowel transplantation (SBT). A recent report indicates that nitric oxide (NO) has cytoprotective effects on bacterial translocation (BT) after SBT. We hypothesized that EGF stimulates the expression of the inducible NO synthase (iNOS) gene in the graft after SBT, followed by increased production of NO, resulting in the decrease of BT. Intestinal epithelial cells (IEC)-6 were treated with EGF and/or IL-1beta in the presence and absence of phosphatidylinositol 3-kinase (PI3-kinase) and EGF receptor kinase inhibitors (LY-294002 and tyrphostin A25). The induction of NO production and iNOS and its signal molecules, including the inhibitory protein of NF-kappaB (IkappaB), NF-kappaB, and Akt, were analyzed. IL-1beta stimulated the degradation of IkappaB and the activation of NF-kappaB but had no effect on iNOS induction. EGF, which had no effect on the NF-kappaB activation and iNOS induction, stimulated the upregulation of type 1 IL-1 receptor (IL-1R1) through PI3-kinase/Akt. Simultaneous addition of EGF and IL-1beta stimulated synergistically the induction of iNOS, leading to the increased production of NO. Our results indicate that EGF and IL-1beta stimulate two essential signals for iNOS induction in IEC-6 cells: the upregulation of IL-1R1 through PI3-kinase/Akt and the activation of NF-kappaB through IkappaB kinase, respectively. Simultaneous addition of EGF and IL-1beta can enhance the production of NO, which may contribute to the cytoprotective effect of EGF against intestinal injury.

A genetic mechanism for cecal atresia: the role of the Fgf10 signaling pathway

BACKGROUND

Intestinal atresia represents a significant surgically correctable cause of intestinal obstruction in neonates. Intestinal development proceeds as a tube-like structure with differentiation along its axis. As the intestine differentiates, the cecum develops at the transition from small to large intestine. Fgf10 is known to serve a key role in budding morphogenesis; however, little is known about its role in the development of this transitional structure. Here we evaluate the effect of Fgf10/Fgfr2b invalidation on the developing cecum.

MATERIALS AND METHODS

Wild-type C57Bl/6, Fgf10(-/-), and Fgfr2b(-/-) embryos harvested from timed pregnant mothers were analyzed for cecal phenotype, Fgf10 expression, and differentiation of smooth muscle actin.

RESULTS

Wt cecal development is first evident at E11.5. FGF10 is discreetly expressed in the area of the developing cecum at early stages of development. One hundred percent of Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with absence of epithelial and muscular layers. The development of neighboring anatomical structures such as the ileocecal valve is not affected by Fgf10/Fgfr2b invalidation.

CONCLUSIONS

FGF10 expression is localized to the cecum early in the normal development of the cecum. Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with complete penetrance. Epithelial and muscular layers of the cecum are not present in the atretic cecum. The Fgf10(-/-) and Fgfr2b(-/-) mutants represent a genetically reproducible animal model of autosomal recessive intestinal atresia.

Effects of growth hormone on intestinal adaptation of rat with short bowel syndrome

AIM: To evaluate the effects of growth hormone (GH) on the residual small intestine of rats with short bowel syndrome (SBS), including adaptive hyperplasia and absorption of glucose and amino acids.

METHODS: Forty Sprague-Dawley (SD) male rats with more than 85% small intestine resected were equally divided into five groups randomly: H-GH group (high dose at 7.5 IU/kg per day), M-GH group (moderate dose at 3.75 IU/kg per day), L-GH group (low dose at 1.88 IU/kg per day), SBS group and sham operation group. From the second to the 15th day after operation, all the GH-managed groups were treated by sc injection twice a day, while SBS group and sham group were managed with same volume normal saline for injection. All samples were gained by laparotomy under anesthesia at the 16th day after operation.

RESULTS: Weight loss of rats in H-GH group (36±4.4 g), which was the least among the four groups except sham group, was significantly less than that in SBS group (94±10.0 g) (P < 0.05). But preoperative body weight of rats in the four groups except sham group was not retrieved. Among all groups there was no significant difference in the length of jejunum and ileum, as well as no significant difference in the morphological variables of colon. Mucosal height of jejunum and ileum was greater in H-GH group and M-GH group (997±65.9 m, 752±79.3 m and 974±67.6 m, 788±75.1 m respectively) than those in SBS group (776±61.0 m, 664±64.0 m) (P < 0.05). Similarly, intestinal wall width of jejunum and ileum was also thicker in H-GH group and M-GH group (1142±65.4 m, 884±91.2 m and 1 145±78.7 m, 895±95.6 m respectively) than those in SBS group (848±194.7 m, 776±57.5 m) (P < 0.05). But mucosal height and intestinal wall width of jejunum and ileum in H-GH group were not significantly greater than those in M-GH group. Blood insulinlike growth factor 1 (IGF-1) concentration and PCNA index of liver did not differ among the five groups. No significant differences of blood glucose and amino acids concentrations were detected after nutritional administration among the five groups.

CONCLUSION: Treatment of SBS with GH only slows body weight decrease rather than promotes body weight gain by the support of enteral nutrition. GH enhances adaptive mucosal hyperplasia after massive resection of small intestine, while its enhanced effect does not parallel its dose increase. Because of GH resistance resulted from the SBS-induced malnutrition,elevation of blood IGF-1 is impaired and absorpton of glucose and amino acids is not enhanced.

Effects of EGF on expression of phosphorylated p44/42 MAPK in rat small intestine after ischemia-reperfusion injury

AIM

To investigate the effects of EGF on the characteristics of phosphrylated p44/42 MAPK expression and its biological significance in EGF-induced gut repair after ischemia-reperfusion (I/R) injury.

METHODS

A total of 80 Wistar rats were randomly divided into four groups, namely EGF treated group (E), normal saline control (R), ischemia group (I) and sham operated control (C). In group E and R, the rats were treated with intravenous EGF 100 μg/kg/rat or normal saline respectively after 45 minutes of superior mesenteric artery occlusion. Blood samples were collected at 2, 6, 12 and 24 hours after reperfusion and plasma D-lactate were determined. Tissue samples from intestine were also taken for histological analysis and immunohistochemical analysis of phospho-p44/42 MAPK.

RESULTS

The changes of histological structure and D-lactate indicated that the intestinal barrier was damaged after intestinal I/R injury, while EGF treatment significantly improved the outcome. In group C and I positive signals of phospho-p44/42 MAPK were mainly located in the cytoplasm of the intestinal villi and crypts, while in group I positive cells increased significantly (P<0.05). In group R, positive signals were found in almost all the cells and the percentage of positive nuclei increased with the time of reperfusion, reaching its peak after 12h of reperfusion. In group E, the percentages were higher than those in group R and the peak of nuclear expression was earlier.

CONCLUSION

EGF administration improves the outcome of I/R induced intestinal damage. After I/R the expression and nuclear translocation of phspho-p44/42 MAPK increases with the time of reperfusion, suggesting its role in intestinal reconstitution. EGF treatment induces its early expression and translocation into the nucleus, suggesting the significance of p44/42 MAPK signaling pathway in EGF-induced gut repair.

Small bowel allografts maintained by administration of bombesin while under immunosuppression

BACKGROUND/PURPOSE

The aim of this study was to determine if Bombesin (BBS) could help maintain the mucosal villus state in small bowel allografts without inducing acute rejection under immunosuppression.

METHODS

Allogeneic small bowel transplantation was performed heterotopically in rats (n = 12). All rats received daily administration of FK506 from postoperative day 0 to day 28. On postoperative day 14, rats were divided into 2 groups of 6 rats each, and administered BBS or normal saline as a control. After 2 weeks of treatment, the rats were killed, and the graft mucosal villus state was evaluated by H&E staining, and crypt cell proliferation analysis was performed using immunohistochemistry with proliferative cell nuclear antigen (PCNA).

RESULTS

Villi were thin, and villus blunting was marked in the control group. The BBS group showed that the villi of the grafts were well maintained, and the volume of the lamina propria mucosa was adequately preserved. The PCNA labeling index of crypt cells in the control group was 40.06 +/- 3.36 (mean +/- SD) and that in the BBS group was 61.02 +/- 4.27. There was a significant difference (P <.001) between the 2 groups.

CONCLUSIONS

BBS maintained allograft epithelial cells and the volume of the lamina propria intestinal mucosa, stimulating proliferation of crypt cells under immunosuppression without inducing acute rejection.

Intestinal and hepatic response to combined partial hepatectomy and small bowel resection in mice

BACKGROUND

Both partial-hepatectomy (PHx) and massive small bowel resection (SBR) are strong mitogenic signals to the remnant liver and intestine, respectively. This study tested the hypothesis that PHx was an additive signal for intestinal adaptation after massive SBR.

METHODS

Male mice underwent either sham SBR or 50% proximal SBR. Mice from these two groups were then subjected to a 70% PHx or sham PHx. After 3 days, parameters of intestinal adaptation and liver regeneration were recorded in the remnant intestine and liver, respectively.

RESULTS

Intestinal adaptation following SBR occurred normally, but was not enhanced after concomitant PHx. On the other hand, SBR impaired the regenerative ability of the liver following PHx.

CONCLUSIONS

Intestinal adaptation after SBR takes priority over liver regeneration after PHx. These data implicate a hierarchy with regard to adaptive alterations to organ loss and endorse an important role for the intestinal mucosa in the regulation of hepatic regeneration.

Bacterial translocation: effects of artificial feeding

The most striking observation when reviewing recent literature in the field of bacterial translocation in the intestine is the small number of publications involving human subjects. Although there are some excellent reviews in this field published during the last 2 years, all experimental contributions come from animal experiments. It is therefore crucial to evaluate how valid the animal models are for human pathophysiology. Studies focusing on translocation as a major pathogenic mechanism are urgently needed to help clinicians to make correct decisions concerning protection of the gut and decide upon nutrition in the intensive care unit.