M1 to M2 macrophage polarization in heparin-binding epidermal growth factor-like growth factor therapy for necrotizing enterocolitis

BACKGROUND

Macrophages can be polarized into proinflammatory (M1) and anti-inflammatory (M2) subtypes. However, whether macrophage polarization plays a role in necrotizing enterocolitis (NEC) remains unknown.

MATERIALS AND METHODS

Macrophages were derived from the THP-1 human monocyte cell line. Apoptosis of human fetal small intestinal epithelial FHs-74 cells was determined by Annexin V/propidium iodide flow cytometry and by Western blotting to detect cleaved caspase-3. The effect of heparin-binding epidermal growth factor-like growth factor (HB-EGF) on macrophage polarization was determined by flow cytometry with M1/M2 markers and real time polymerase chain reaction. In vivo, experimental NEC was induced in mouse pups by repeated exposure to hypoxia, hypothermia, and hypertonic feedings. Intestinal histologic sections were subjected to immunohistochemical staining for the detection of M1 and M2 macrophages.

RESULTS

In vitro, FHs-74 cell apoptosis was increased after coculture with macrophages and lipopolysaccharide (LPS). This apoptosis was increased by exposure to M1-conditioned medium and suppressed by exposure to M2-conditioned medium. HB-EGF significantly decreased LPS-induced M1 polarization and promoted M2 polarization via signal transducers and activators of transcription 3 activation. Addition of HB-EGF to LPS-stimulated macrophages suppressed the proapoptotic effects of the macrophages on FHs-74 cells. In vivo, we found enhanced intestinal macrophage infiltration in pups subjected to NEC, most of which were M1 macrophages. HB-EGF treatment of pups subjected to experimental NEC significantly reduced M1 and increased M2 polarization and protected the intestines from NEC.

CONCLUSIONS

M1 macrophages promote NEC by increasing intestinal epithelial apoptosis. HB-EGF protects the intestines from NEC by preventing M1 and promoting M2 polarization.

Enriched Intestinal Stem Cell Seeding Improves the Architecture of Tissue-Engineered Intestine

OBJECTIVE

To develop a methodology to separate intestinal stem cell (ISC)-enriched crypts from differentiated epithelial cell (DEC)-containing villi to improve the morphology of tissue-engineered intestine (TEI).

METHODS

Small intestinal tissues from 5- to 7-day-old transgenic Lgr5-EGFP mice (with fluorescently labeled ISCs) were used to measure the height of villi and the depth of crypts. Based on the significant size difference between crypts and villi, a novel cell filtration system was developed. Filtration of mixed organoid units from full-thickness intestine of transgenic Lgr5-EGFP mice allowed determination of the percentage of ISCs in the different size-based filtration fractions obtained. In vivo, 5-7-day-old Lewis rat pups were used as cell donors to obtain purified crypts and villi, and the dams of the pups served as recipients. Flat and tubular polyglycolic acid (PGA) scaffolds were seeded with either ISC-enriched crypts or DEC-containing villi and implanted intra-abdominally on the anterior abdominal wall. After 1, 3, 7, 14, 21, and 28 days of in vivo incubation, explants were processed for histologic evaluation.

RESULTS

Small intestine from transgenic Lgr5-EGFP mice contained villi with an average height of 134.89±41.91 μm and crypts with an average depth of 49.59±8.95 μm. After filtration, we found that the 100-200 μm fractions contained relatively pure villi in which DECs were located, whereas the 25-70 μm range fractions contained concentrated crypts in which ISCs were located. In vivo, flat PGA scaffolds implanted with purified crypts formed well-developed mucosa by day 14 postimplantation, whereas flat scaffolds seeded with villi were replaced with fibrous tissue. Tubular scaffolds seeded with the crypt fraction developed a well-formed mucosal layer on the interior surface, with 80.9% circumferential mucosal engraftment and an average villous height of 478±65 μm, which was very close to native intestine (512±98 μm), whereas tubular scaffolds seeded with the villous fraction only had 21.7% circumferential mucosal engraftment and an average villous height of 243±78 μm.

CONCLUSION

The novel filtration system described can effectively and efficiently isolate ISC-containing crypts. TEI produced from ISC-containing crypts has an improved morphology that is similar to native intestine.

An unusual case of foreign body pulmonary embolus: case report and review of penetrating trauma at a pediatric trauma center

PURPOSE

Penetrating thoracic trauma is relatively rare in the pediatric population. Embolization of foreign bodies from penetrating trauma is very uncommon. We present a case of a 6-year-old boy with a penetrating foreign body from a projectile dislodged from a lawn mower. Imaging demonstrated a foreign body that embolized to the left pulmonary artery, which was successfully treated non-operatively.

METHODS

We reviewed the penetrating thoracic trauma patients in the trauma registry at our institution between 1/1/03 and 12/31/12. Data collected included demographic data, procedures performed, complications and outcome.

RESULTS

Sixty-five patients were identified with a diagnosis of penetrating thoracic trauma. Fourteen of the patients had low velocity penetrating trauma and 51 had high velocity injuries. Patients with high velocity injuries were more likely to be older and less likely to be Caucasian. There were no statistically significant differences between patients with low vs. high velocity injuries regarding severity scores or length of stay. There were no statistically significant differences in procedures required between patients with low and high velocity injuries.

CONCLUSIONS

Penetrating thoracic trauma is rare in children. The case presented here represents the only report of cardiac foreign body embolus we could identify in a pediatric patient.

Development and implementation of an electronic health record generated surgical handoff and rounding tool

Electronic health records (EHR) have been adopted across the nation at tremendous effort and expense. The purpose of this study was to assess improvements in accuracy, efficiency, and patient safety for a high-volume pediatric surgical service with adoption of an EHR-generated handoff and rounding list. The quality and quantity of errors were compared pre- and post-EHR-based list implementation. A survey was used to determine time spent by team members using the two versions of the list. Perceived utility, safety, and quality of the list were reported. Serious safety events determined by the hospital were also compared for the two periods. The EHR-based list eliminated clerical errors while improving efficiency by automatically providing data such as vital signs. Survey respondents reported 43 min saved per week per team member, translating to 372 work hours of time saved annually for a single service. EHR-based list users reported higher satisfaction and perceived improvement in efficiency, accuracy, and safety. Serious safety events remained unchanged. In conclusion, creation of an EHR-based list to assist with daily handoffs, rounding, and patient management demonstrated improved accuracy, increased efficiency, and assisted in maintaining a high level of safety.

A pain in the NEC: research challenges and opportunities

This lecture will describe how the properties of heparin-binding EFG-like growth factor (HB-EGF) can be utilized to protect the intestines from necrotizing enterocolitis (NEC), to augment the effects of stem cells in the treatment of NEC, and to improve the production of tissue-engineered intestine. It will also explore the role of the enteric nervous system in the development of NEC.

HB-EGF augments the ability of mesenchymal stem cells to attenuate intestinal injury

BACKGROUND

We have previously demonstrated that heparin-binding EGF-like growth factor (HB-EGF) and mesenchymal stem cell (MSC) administration protect the intestines from ischemia/reperfusion (I/R) injury in vivo, with amniotic fluid-derived MSC (AF-MSC) being more efficacious than bone marrow-derived MSC (BM-MSC). The goal of the current study was to determine whether the protective effects of HB-EGF were from direct effects on MSC or via alternative mechanisms.

METHODS

Murine MSC were transfected with an HB-EGF plasmid or control plasmid by electroporation. Mice were subjected to segmental intestinal I/R injury and received either BM-MSC or AF-MSC either with or without exogenous HB-EGF, or BM-MSC or AF-MSC that endogenously over-expressed HB-EGF. MSC engraftment, intestinal histologic injury, and intestinal permeability were quantified.

RESULTS

There was increased MSC engraftment into injured compared to uninjured intestine. HB-EGF increased AF-MSC engraftment into injured intestine. Administration of HB-EGF and MSC improved intestinal histology and intestinal permeability after I/R injury, with AF-MSC being most efficacious. The effect of HB-EGF on MSC was similar when the growth factor was administered exogenously, or when it was overexpressed endogenously.

CONCLUSIONS

The effect of HB-EGF on AF-MSC was similar with both exogenous administration and endogenous overexpression of the growth factor, implying that HB-EGF has a direct effect on AF-MSC. This information may assist in guiding potential future AF-MSC-based therapies for patients at risk of intestinal ischemic injuries.

Heparin-binding EGF-like growth factor (HB-EGF) promotes cell migration and adhesion via focal adhesion kinase

BACKGROUND

Cell migration and adhesion are essential in intestinal epithelial wound healing and recovery from injury. Focal adhesion kinase (FAK) plays an important role in cell-extracellular matrix signal transduction. We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) promotes intestinal epithelial cell (IEC) migration and adhesion in vitro. The present study was designed to determine whether FAK is involved in HB-EGF-induced IEC migration and adhesion.

MATERIALS AND METHODS

A scrape wound healing model of rat IECs was used to examine the effect of HB-EGF on FAK-dependent cell migration in vitro. Immunofluorescence and Western blot analyses were performed to evaluate the effect of HB-EGF on the expression of phosphorylated FAK (p-FAK). Cell adhesion assays were performed to determine the role of FAK in HB-EGF-induced cell adhesion on fibronectin (FN).

RESULTS

HB-EGF significantly increased healing after scrape wounding, an effect that was reversed in the presence of an FAK inhibitor 14 (both with P < 0.05). HB-EGF increased p-FAK expression and induced p-FAK redistribution and actin reorganization in migrating rat IECs. Cell adhesion and spreading on FN were significantly increased by HB-EGF (P < 0.05). FAK inhibitor 14 significantly inhibited both intrinsic and HB-EGF-induced cell adhesion and spreading on FN (both with P < 0.05).

CONCLUSIONS

FAK phosphorylation and FAK-mediated signal transduction play essential roles in HB-EGF-mediated IEC migration and adhesion.

Heparin-binding epidermal growth factor-like growth factor restores Wnt/β-catenin signaling in intestinal stem cells exposed to ischemia/reperfusion injury

BACKGROUND

We have previously demonstrated that heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) protects the intestines from injury in several different experimental animal models. In the current study, we investigated whether the ability of HB-EGF to protect the intestines from ischemia/reperfusion (I/R) injury was related to its effects on Wnt/β-catenin signaling in intestinal stem cells (ISC).

METHODS

Lucien-rich repeat-containing G-protein-coupled receptor 5 (LGR5)-enhanced green fluorescent protein (EGFP) transgenic (TG) mice with fluorescently labeled ISC, as well as the same mice treated with intraluminal HB-EGF or genetically engineered to overexpress HB-EGF, were exposed to segmental mesenteric artery occlusion (sMAO) to the terminal ilium. Wnt/β-catenin signaling was evaluated using immunofluorescent staining and Western blotting.

RESULTS

LGR5 expression and Wnt/β-catenin signaling in the ISC of the terminal ilium of LGR5-EGFP TG mice was significantly reduced 24 hours after sMAO. Intraluminal administration of HB-EGF or HB-EGF overexpression in these mice led to preservation of LGR5 expression and Wnt/β-catenin signaling.

CONCLUSION

These data show that HB-EGF preserves Wnt/β-catenin signaling in ISC after I/R injury.

Effects of lipopolysaccharide-induced inflammation on the interstitial cells of Cajal

Interstitial cells of Cajal (ICC) have recently been found to display phenotypic changes. The present study is designed to determine whether phenotypic changes occur in ICC associated with an inflammatory microenvironment and whether the ICC phenotype could be recovered after the discontinuation of inflammatory stimuli. Immunohistochemistry studies revealed that the functional ICC marker, c-kit, was markedly reduced in patients with Hirschsprung's disease (n = 34) compared with controls (n = 12), whereas another marker of ICC, CD34, was not altered significantly. Compared with the vehicle group (n = 6), intraperitoneal injection of lipopolysaccharide (LPS; 1.5 mg/kg) in mice (n = 6) significantly induced plasma tumor necrosis factor-alpha (TNF-α) levels as determined by enzyme-linked immunosorbent assay. Western blot and real-time polymerase chain reaction assessment further showed that LPS injection markedly suppressed intestinal c-kit protein and mRNA expression, which could be blocked by Toll-like receptor 4 (TLR4) deficiency (n = 6) rather than TLR2 deficiency (n = 6) and had no effects on CD34. Compared with the vehicle group (n = 6), intraperitoneal TNF-α (30 μg/kg) administration (n = 6) also significantly reduced intestinal c-kit protein and mRNA levels but not CD34 levels. However, the reduction of c-kit induced by TNF-α injection was not suppressed by TLR4 deficiency (n = 6). Intestinal c-kit protein and mRNA levels were markedly restored after the discontinuation of TNF-α administration for 7 days. Moreover, immunofluorescence analysis of primary ICC further confirmed that exposure to TNF-α for 24 h suppressed c-kit expression, which could be restored after discontinuation of TNF-α exposure. CD34 expression was not altered upon exposure to TNF-α. Thus, phenotypic changes in ICC occur in an inflammatory microenvironment in the gut and LPS, TLR4 and TNFα are crucial to this process.

Heparin-binding EGF-like growth factor (HB-EGF) therapy for intestinal injury: Application and future prospects

Throughout the past 20 years, we have been investigating the potential therapeutic roles of heparin-binding EGF-like growth factor (HB-EGF), a member of the epidermal growth factor family, in various models of intestinal injury including necrotizing enterocolitis (NEC), intestinal ischemia/reperfusion (I/R) injury, and hemorrhagic shock and resuscitation (HS/R). Our studies have demonstrated that HB-EGF acts as an effective mitogen, a restitution-inducing reagent, a cellular trophic factor, an anti-apoptotic protein and a vasodilator, via its effects on various cell types in the intestine. In the current paper, we have reviewed the application and therapeutic effects of HB-EGF in three classic animal models of intestinal injury, with particular emphasis on its protection of the intestines from NEC. Additionally, we have summarized the protective functions of HB-EGF on various target cells in the intestine. Lastly, we have provided a brief discussion focusing on the future development of HB-EGF clinical applications for the treatment of various forms of intestinal injury including NEC.

Synergistic effects of HB-EGF and mesenchymal stem cells in a murine model of intestinal ischemia/reperfusion injury

BACKGROUND

We have previously demonstrated that heparin-binding EGF-like growth factor (HB-EGF) administration protects the intestines from ischemia/reperfusion (I/R) injury in vivo. We have also shown that HB-EGF promotes mesenchymal stem cell (MSC) proliferation and migration in vitro. The goals of the current study were to examine the effects of HB-EGF and both bone marrow (BM)- and amniotic fluid (AF)-derived MSC on intestinal I/R injury in vivo.

MATERIALS AND METHODS

MSC were isolated from pan-EGFP mice, expanded, and purified. Pluripotency was confirmed by induced differentiation. Mice were subjected to terminal ileum I/R and received either: (1) no therapy; (2) HB-EGF; (3) BM-MSC; (4) HB-EGF+BM-MSC; (5) AF-MSC; or (6) HB-EGF+AF-MSC. MSC engraftment, histologic injury, and intestinal permeability were quantified.

RESULTS

There was increased MSC engraftment into injured compared to uninjured intestine for all experimental groups, with significantly increased engraftment for AF-MSC+HB-EGF compared to AF-MSC alone. Administration of HB-EGF and MSC improved intestinal histology and intestinal permeability after I/R injury. The greatest improvement was with combined administration of HB-EGF+AF-MSC.

CONCLUSIONS

Both HB-EGF alone and MSC alone can protect the intestines from I/R injury, with synergistic efficacy occurring when HB-EGF and AF-MSC are administered together.

A technique for systemic mesenchymal stem cell transplantation in newborn rat pups

Mesenchymal stem cells (MSC) have the potential to aid tissue regeneration. Intravenous (IV) MSC administration is currently being assessed following tissue injury. However, few studies have been performed to establish a safe and effective method of IV MSC infusion for newborns. We have established a safe, nontraumatic and effective technique for systemic MSC transplantation in newborn rats. Yellow-fluorescent-protein (YFP)-labeled MSC were characterized using MSC markers and their differentiation potential was confirmed. Rat pups were delivered by C-section on gestational day 21. The umbilical vein (UV) was cannulated and used for IV injection of MSC or saline control, which was performed under ultrasonographic imaging. An additional control group consisted of UV MSC injection in adult mice. Mean operating time, success rate of cannulation and death rate were recorded. YFP-MSC quantification in multiple organs was performed. Mean operating time was 3.9 ± 1.1 min. The success of UV MSC injection was 92.8%. The immediate and 24 hr delayed death rate for rat pups was significantly lower than that of adult mice (p < .05). No pups receiving saline injection died. After locating the patent foramen ovale (PFO) of newborn pups by ultrasonographic imaging, extra pulse-waves and wave-shape changes were detected when MSC were injected. The number of YFP-MSC was 15.8 ± 4.1 cells per visual field (CPVF) in the lungs, 2.9 ± 1.2 CPVF in the heart, and 19.8 ± 5.0 CPVF in the intestines. We conclude that IV MSC infusion through the UV is a convenient, safe, and effective method for systemic MSC transplantation in prematurely delivered newborn rats.

Diffuse intestinal ganglioneuromatosis in a child

A 7 year old male with a history of congenital neutropenia and growth hormone deficiency presented with abdominal pain, fevers, and diarrhea. Imaging and endoscopy revealed significant inflammation of the ascending colon with stenosis at the level of the hepatic flexure. A right hemicolectomy was performed, and pathologic findings were consistent with diffuse intestinal ganglioneuromatosis. Due to recurrent mass effect at the intestinal anastomotic site detected radiologically, a second intestinal resection was performed 7 months later. Genetic testing was negative for mutations in the RET protooncogene, NF1 and PTEN tumor suppressor genes. We report a case of diffuse intestinal ganglioneuromatosis in a child with congenital neutropenia.

The role of the intestinal microcirculation in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) continues to be a devastating inflammatory disease of the newborn intestine. Despite advances in management, morbidity and mortality remain high. While it is clear that intestinal ischemia plays a large role in disease pathogenesis, attempts to link NEC to intestinal macrovascular derangement have been largely unsuccessful. More recently, there has been a concerted effort to characterize the pathologic changes of the intestinal microcirculation in response to intestinal injury, including NEC. This microcirculatory regulation is controlled by a balance of vasoconstrictor and vasodilator forces. Vasoconstriction is mediated primarily by endothelin-1 (ET-1), while vasodilation is mediated primarily by nitric oxide (NO). These chemical mediators have been implicated in many aspects of intestinal ischemic injury and NEC, with the balance shifting toward increased vasoconstriction associated with intestinal injury. With a proper understanding of these antagonistic forces, potential therapeutic avenues may result from improving this pathologic microcirculatory dysregulation.

HB-EGF promotes intestinal restitution by affecting integrin-extracellular matrix interactions and intercellular adhesions

Restitution is a critical form of intestinal epithelial cell (IEC) healing. We have previously shown that heparin-binding epidermal-like growth factor (HB-EGF) is necessary for IEC restitution; however, the mechanisms by which HB-EGF promotes restitution remain poorly understood. This study was designed to investigate whether HB-EGF promotes intestinal restitution by affecting integrin-extracellular matrix (ECM) interactions and intercellular adhesions. The effect of HB-EGF administration was examined in a murine necrotizing enterocolitis (NEC) model in vivo and an IEC line scrape-wound healing model in vitro. We evaluated the effect of HB-EGF on the expression of integrins, E-cadherin/β-catenin, and integrin α5β1-dependent cell-ECM interactions. We found that HB-EGF promoted intestinal restitution and the expression of integrin α5β1. HB-EGF promoted integrin α5β1-dependent cell adhesion and spreading. In addition, HB-EGF decreased the expression E-cadherin/β-catenin, via the activation of v-erb-b2 erythroblastic leukemia viral oncogene homolog (ErbB-1). We conclude that HB-EGF promotes intestinal restitution by affecting integrin-ECM interactions and intercellular adhesions.

Heparin-binding epidermal growth factor-like growth factor promotes murine enteric nervous system development and enteric neural crest cell migration

BACKGROUND/PURPOSE

Developmental defects of the enteric nervous system lead to a variety of disorders including Hirschprung disease. We have previously shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF) exerts neuroprotective effects on injured neurons. The goals of this study were to assess the role of HB-EGF in enteric nervous system development and to evaluate the effect of HB-EGF on enteric neural crest-derived cell (ENCC) migration in the developing gastrointestinal tract of mice.

MATERIALS AND METHODS

HB-EGF immunohistochemistry was used to examine HB-EGF protein expression in the hindgut of embryonic mice. Gut specimens were stained for PGP9.5 (a neuronal cell marker) to examine the extent of ENCC migration in the intestine at different embryonic stages in HB-EGF knockout (KO) and wild-type (WT) mice. Embryonic gut organ cultures were established to examine the effect of HB-EGF on ENCC migration.

RESULTS

The expression of HB-EGF was limited to the endodermal epithelium of the hindgut in early gestation, but rapidly involved the hindgut mesenchyme after ENCC migrated into this region. ENCC migration was significantly delayed in HB-EGF KO compared with WT embryos, leading to defects in neural colonization of the distal gut in postnatal HB-EGF KO mice. Addition of HB-EGF to WT embryonic intestine significantly promoted ENCC migration, as demonstrated by a significant increase in the ratio of ENCC migration distance toward the distal hindgut/total colon length (78% ± 4% vs 53% ± 2%, P = .001).

CONCLUSIONS

Deletion of the HB-EGF gene leads to enteric nervous system developmental defects. HB-EGF stimulates ENCC migration in the gut, supporting a potential role for administration of HB-EGF in the future for the treatment of patients with intestinal neuronal disorders.

Heparin-binding epidermal growth factor-like growth factor and mesenchymal stem cells act synergistically to prevent experimental necrotizing enterocolitis

BACKGROUND

We have shown that administration of heparin-binding EGF (epidermal growth factor)-like growth factor (HB-EGF) protects the intestines from experimental necrotizing enterocolitis (NEC). We have also demonstrated that systemically administered mesenchymal stem cells (MSC) can engraft into injured intestines. This study investigated the effects of HB-EGF on MSC in vitro, and whether MSC and HB-EGF can act synergistically to prevent NEC in vivo.

STUDY DESIGN

In vitro, the effect of HB-EGF on MSC proliferation, migration, and apoptosis was determined. In vivo, rat pups received MSC either intraperitoneally (IP) or intravenously (IV). Pups were assigned to 1 of 7 groups: Group 1, breast-fed; Group 2, experimental NEC; Group 3, NEC+HB-EGF; Group 4, NEC+MSC IP; Group 5, NEC+HB-EGF+MSC IP; Group 6, NEC+MSC IV; or Group 7, NEC+HB-EGF+MSC IV. Mesechymal stem cell engraftment, histologic injury, intestinal permeability, and mortality were determined.

RESULTS

Heparin-binding EGF-like growth factor promoted MSC proliferation and migration, and decreased MSC apoptosis in vitro. In vivo, MSC administered IV had increased engraftment into NEC-injured intestine compared with MSC administered IP (p < 0.05). Heparin binding EGF-like growth factor increased engraftment of IP-administered MSC (p < 0.01) and IV-administered MSC (p < 0.05). Pups in Groups 3 to 7 had a decreased incidence of NEC compared with nontreated pups (Group 2), with the lowest incidence in pups treated with HB-EGF+MSC IV (p < 0.01). Pups in Group 7 had a significantly decreased incidence of intestinal dilation and perforation, and had the lowest intestinal permeability, compared with other treatment groups (p < 0.01). Pups in all experimental groups had significantly improved survival compared with pups exposed to NEC, with the best survival in Group 7 (p < 0.05).

CONCLUSIONS

Heparin-binding EGF-like growth factor and MSC act synergistically to reduce injury and improve survival in experimental NEC.

Heparin-binding epidermal growth factor-like growth factor improves intestinal barrier function and reduces mortality in a murine model of peritonitis

BACKGROUND

The morbidity and mortality associated with bacterial peritonitis remain high. Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) is a potent intestinal cytoprotective agent. The aim of this study was to evaluate the effect of HB-EGF in a model of murine peritonitis.

METHODS

HB-EGF(-/-) knockout (KO) mice and their HB-EGF(+/+) wild-type (WT) counterparts were subjected to sham operation, cecal ligation and puncture (CLP), or CLP with HB-EGF treatment (800 μg/kg IP daily). Villous length, intestinal permeability, intestinal epithelial cell (IEC) apoptosis, bacterial load in peritoneal fluid (PF) and mesenteric lymph nodes (MLN), inflammatory cytokine levels, and survival were determined.

RESULTS

After exposure to CLP, HB-EGF KO mice had significantly shorter villi (1.37 ± 0.13 vs 1.96 ± 0.4 relative units; P < .03), increased intestinal permeability (17.01 ± 5.18 vs 11.50 ± 4.67 nL/min/cm2; P < .03), increased IEC apoptotic indices (0.0093 ± 0.0033 vs 0.0016 ± 0.0014; P < .01), and increased bacterial counts in PF (25,313 ± 17,558 vs 11,955 ± 6,653 colony forming units [CFU]/mL; P < .05) and MLN (19,009 ± 11,200 vs 5,948 ± 2,988 CFU/mL/g; P < .01) compared with WT mice. Administration of HB-EGF to WT and HB-EGF KO mice exposed to CLP led to significantly increased villous length and decreased intestinal permeability, IEC apoptosis and bacterial counts in MLN (P < .05). Survival of HB-EGF KO mice subjected to CLP was significantly improved with administration of HB-EGF (P < .05).

CONCLUSION

HB-EGF gene KO increases susceptibility to peritonitis-induced intestinal injury, which can be reversed by administration of HB-EGF. These results support a protective role of HB-EGF in peritonitis-induced sepsis.

Heparin-binding epidermal growth factor-like growth factor protects mesenchymal stem cells

BACKGROUND

We have previously demonstrated that mesenchymal stem cell (MSC) administration protects the intestines from injury in a mouse model of intestinal ischemia/reperfusion injury. We have also shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a potent intestinal cytoprotective agent in vivo that can protect the intestines by way of its effects on stem cells. The goal of the present study was to examine the effects of HB-EGF on both amniotic fluid (AF)- and bone marrow (BM)-derived MSCs in vitro.

METHODS

MSCs were isolated from the AF and BM of pan-EGFP mice, grown in MSC-specific culture medium, and purified by sequential passages according to their adherence properties. Pluripotency was confirmed by induced differentiation. After incubation of MSCs with HB-EGF, proliferation was quantified using the CyQuant cell proliferation assay kit under normoxic and anoxic conditions. Chemotaxis was quantified using the CHEMICON QCM cell migration kit, and apoptosis was determined using caspase-3 immunohistochemistry after exposure of the MSCs to anoxic stress.

RESULTS

AF-MSCs and BM-MSCs showed significantly increased proliferation and migration in response to HB-EGF. HB-EGF significantly protected AF-MSCs and BM-MSCs from anoxia-induced apoptosis. The proliferative and anti-apoptotic effects of HB-EGF were even more pronounced in AF-MSCs than in BM-MSCs.

CONCLUSIONS

These results have demonstrated that HB-EGF acts as a mitogenic and chemotactic agent for MSCs that protects MSCs from injury. These findings could have important implications for future experiments designed to use MSCs to protect the intestines from injury.

Heparin-binding epidermal growth factor-like growth factor suppresses experimental liver fibrosis in mice

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a cytoprotective agent in several organ systems but its roles in liver fibrosis are unclear. We studied the roles of HB-EGF in experimental liver fibrosis in mice and during hepatic stellate cell (HSC) activation. Thioacetamide (TAA; 100 mg/kg) was administered by intraperitoneal injection three times a week for 4 weeks to wild-type HB-EGF(+/+) or HB-EGF-null (HB-EGF(-/-)) male mice. Livers were examined for histology and expression of key fibrotic markers. Primary cultured HSCs isolated from untreated HB-EGF(+/+) or HB-EGF(-/-) mice were examined for fibrotic markers and/or cell migration either during culture-induced activation or after exogenous HB-EGF (100 ng/ml) treatment. TAA induced liver fibrosis in both HB-EGF(+/+) and HB-EGF(-/-) mice. Hepatic HB-EGF expression was decreased in TAA-treated HB-EGF(+/+) mice by 37.6% (P<0.05) as compared with animals receiving saline alone. HB-EGF(-/-) mice treated with TAA showed increased hepatic α-smooth muscle actin-positive cells and collagen deposition, and, as compared with HB-EGF(+/+) mice, TAA-stimulated hepatic mRNA levels in HB-EGF(-/-) mice were, respectively, 2.1-, 1.7-, 1.8-, 2.2-, 1.2- or 3.3-fold greater for α-smooth muscle actin, α1 chain of collagen I or III (COL1A1 or COL3A1), transforming growth factor-β1, connective tissue growth factor or tissue inhibitor of metalloproteinase-1 (P<0.05). HB-EGF expression was detectable in primary cultured HSCs from HB-EGF(+/+) mice. Both endogenous and exogenous HB-EGF inhibited HSC activation in primary culture, and HB-EGF enhanced HSC migration. These findings suggest that HB-EGF gene knockout in mice increases susceptibility to chronic TAA-induced hepatic fibrosis and that HB-EGF expression or action is associated with suppression of fibrogenic pathways in HSCs.

Heparin-binding EGF-like growth factor protects intestinal stem cells from injury in a rat model of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is an often catastrophic disease that typically affects premature newborns. Although the exact etiology of NEC is uncertain, the disease is associated with formula feeding, bacterial colonization of the gut, hypoxia and hypoperfusion. In light of the pathogenesis of NEC, the integrity and function of the intestinal mucosa has a major defensive role against the initiation of NEC. Various forms of intestinal injury, including NEC, injure the intestinal epithelial cell (IEC) lineages, including the intestinal stem cells (ISCs), thereby disrupting the normal homeostasis needed to maintain gut barrier function. In the current study, we examined the effects of heparin-binding EGF-like growth factor (HB-EGF) administration on enterocytes, goblet cells, neuroendocrine cells and ISCs in a newborn rat model of experimental NEC. We also examined the cytoprotective effects of HB-EGF on ISCs in in vitro cell cultures and in ex vivo crypt-villous organoid cultures. We found that HB-EGF protects all IEC lineages, including ISCs, from injury. We further found that HB-EGF protects isolated ISCs from hypoxic injury in vitro, and promotes ISC activation and survival, and the expansion of crypt transit-amplifying cells, in ex vivo crypt-villous organoid cultures. The protective effects of HB-EGF were dependent on EGF receptor activation, and were mediated via the MEK1/2 and PI3K signaling pathways. These results show that the intestinal cytoprotective effects of HB-EGF are mediated, at least in part, through its ability to protect ISCs from injury.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) preserves gut barrier function by blocking neutrophil-endothelial cell adhesion after hemorrhagic shock and resuscitation in mice

BACKGROUND

We have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF) protects the intestines from injury in several different animal models, including hemorrhagic shock and resuscitation (HS/R). The current study was designed to explore the mechanisms underlying the anti-inflammatory role of HB-EGF in preservation of gut barrier function after injury.

METHODS

In vivo, HS/R was induced in wild-type and neutropenic mice, with or without administration of HB-EGF, and intestinal permeability determined by use of the everted gut sac method. In vitro, cultured human umbilical vein endothelial cells (HUVECs) and freshly isolated human peripheral blood mononuclear cells (PMNs) were used to determine the effects of HB-EGF on HUVEC-PMN adhesion, reactive oxygen species production in PMN, adhesion molecule expression in HUVEC and PMN, and the signaling pathways involved.

RESULTS

We found that administration of HB-EGF to healthy mice led to preservation of gut barrier function after HS/R. Likewise, induction of neutropenia in mice also led to preservation of gut barrier function after HS/R. Administration of HB-EGF to neutropenic mice did not lead to further improvement in gut barrier function. In vitro studies showed that HB-EGF decreased neutrophil-endothelial cell (PMN-EC) adherence by down-regulating adhesion molecule expression in EC via the phosphoinositide 3-kinase-Akt pathway, and by inhibiting adhesion molecule surface mobilization and reactive oxygen species production in PMN.

CONCLUSION

These results indicate that HB-EGF preserves gut barrier function by inhibiting PMN and EC activation, thereby blocking PMN-EC adherence after HS/R in mice, and support the future use of HB-EGF in disease states manifested by hypoperfusion injury.

HB-EGF improves intestinal microcirculation after hemorrhagic shock

BACKGROUND

The goal of this study was to determine the role of heparin-binding epidermal growth factor-like growth factor (HB-EGF) as a mediator of gut microcirculation after hemorrhagic shock and resuscitation (HS/R) in mice.

MATERIALS AND METHODS

HS/R was induced in HB-EGF knockout (KO) and wild type (WT) mice. Ink-gelatin injection and vascular corrosion casting were performed to visualize the gut microvasculature. The degree of gut microcirculatory injury was graded using five patterns of injury (1-5) according to the severity of microvascular hypoperfusion. Statistical analyses were performed using linear mixed models with P < 0.05 considered statistically significant.

RESULTS

HB-EGF KO mice subjected to HS/R had significantly decreased perfusion of the gut microvasculature compared with WT mice subjected to HS/R (P = 0.0001). HB-EGF KO mice subjected to HS/R and treated with exogenous HB-EGF had significantly increased gut microvascular perfusion compared with non-HB-EGF treated KO mice (P = 0.01). Lastly, WT mice subjected to HS/R and treated with HB-EGF had significantly increased gut microvascular perfusion compared with non-HB-EGF-treated WT mice (P = 0.04).

CONCLUSIONS

HB-EGF improves gut microcirculation after HS/R. These findings support the clinical use of HB-EGF in protection of the intestines from disease states associated with intestinal hypoperfusion injury.

Poly(ADP-ribose) polymerase-1: a novel therapeutic target in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of infancy, afflicting 11% of infants born 22-28 wk GA. Both inflammation and oxidation may be involved in NEC pathogenesis through reactive nitrogen species production, protein oxidation, and DNA damage. Poly(ADP-ribose) polymerase-1 (PARP-1) is a critical enzyme activated to facilitate DNA repair using nicotinamide adenine dinucleotide (NAD+) as a substrate. However, in the presence of severe oxidative stress and DNA damage, PARP-1 overactivation may ensue, depleting cells of NAD+ and ATP, killing them by metabolic catastrophe. Here, we tested the hypothesis that NO dysregulation in intestinal epithelial cells during NEC leads to marked PARP-1 expression and that administration of a PARP-1 inhibitor (nicotinamide) attenuates intestinal injury in a newborn rat model of NEC. In this model, 56% of control pups developed NEC (any stage) versus 14% of pups receiving nicotinamide. Forty-four percent of control pups developed high-grade NEC (grades 3-4), whereas only 7% of pups receiving nicotinamide developed high-grade NEC. Nicotinamide treatment protects pups against intestinal injury incurred in the newborn rat NEC model. We speculate that PARP-1 overactivation in NEC may drive mucosal cell death in this disease and that PARP-1 may be a novel therapeutic target in NEC.

Mice overexpressing the gene for heparin-binding epidermal growth factor-like growth factor (HB-EGF) have increased resistance to hemorrhagic shock and resuscitation

BACKGROUND

The aim of the current study was to determine whether overexpression of heparin-binding epidermal growth factor-like growth factor (HB-EGF) could protect the intestines from injury after hemorrhagic shock and resuscitation in mice.

METHODS

Hemorrhagic shock and resuscitation was induced in HB-EGF transgenic and wild type mice. Cross-reacting material 197 (5 mg/kg) was administered to a subset of HB-EGF transgenic mice to block the overexpressed HB-EGF. Intestinal histologic injury scores, intestinal epithelial cell apoptosis indices, and gut barrier function were determined. The Student t test and 1-way analysis of variance were employed to compare the differences between groups.

RESULTS

All mice subjected to hemorrhagic shock and resuscitation had significantly increased intestinal histologic injury scores, apoptosis indices, and intestinal permeability compared with sham-operated mice. Compared with wild type mice, HB-EGF transgenic mice had significantly decreased histologic injury (mean injury grade 2.79 ± 0.84 vs 3.88 ± 1.43, P = .02), apoptosis indices (mean apoptosis index 8.77 ± 5.23 vs 17.91 ± 13.23, P = .03), and mucosal permeability (FITC-dextran 4 clearance 13.06 ± 5.67 vs 20.03 ± 7.81 nL/min/ m(2), P = .02) at 3 hours of reperfusion. HB-EGF transgenic mice subjected to hemorrhagic shock and resuscitation and treated with cross-reacting material 197 had a significantly increased histologic injury (mean injury grade 3.63 ± 1.00 vs 2.79 ± 0.84, P = .04) and mucosal permeability (FITC-dextran 4 clearance 22.87 ± 9.69 vs 13.06 ± 5.67 nL/min/cm2, P = .01) at 3 hours of reperfusion compared with non-cross-reacting material 197 treated transgenic mice, with no significant changes in apoptosis indices. Cross-reacting material 197 did not reverse the decreased apoptosis observed in HB-EGF transgenic mice subjected to hemorrhagic shock and resuscitation, which suggests that mechanisms in addition to decreased apoptosis may be responsible for the intestinal cytoprotective effects of endogenous HB-EGF overexpression.

CONCLUSION

Overexpression of HB-EGF increases resistance to hemorrhagic shock and resuscitation in mice.

Heparin-binding epidermal growth factor-like growth factor overexpression in transgenic mice increases resistance to necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency and the leading surgical cause of death in premature infants. We have shown that administration of exogenous heparin-binding epidermal growth factor-like growth factor (HB-EGF) in mice protects the intestines from experimental NEC. The aim of the current study was to evaluate the effect of gain-of-function of endogenous HB-EGF on susceptibility to NEC.

METHODS

Neonatal HB-EGF transgenic (TG) mice and their wild-type (WT) counterparts were exposed to experimental NEC. An additional group of HB-EGF TG pups were also exposed to NEC, but received the HB-EGF antagonist cross-reacting material 197 (CRM197) injected subcutaneously immediately after birth. To examine gut barrier function, HB-EGF TG and WT pups received intragastric fluorescein isothiocyanate-labeled dextran under basal and stressed conditions, and serum fluorescein isothiocyanate-labeled dextran levels were measured.

RESULTS

Wild-type mice had an incidence of NEC of 54.2%, whereas HB-EGF TG mice had a significantly decreased incidence of NEC of 22.7% (P = .03). Importantly, administration of CRM197 to HB-EGF TG pups significantly increased the incidence of NEC to 65% (P = .004). HB-EGF TG mice had significantly decreased intestinal permeability compared to WT mice both under basal and stressed conditions.

CONCLUSIONS

Our results provide evidence that overexpression of the HB-EGF gene decreases susceptibility to NEC and that administration of the HB-EGF antagonist CRM197 reverses this protective effect.

Heparin-binding EGF-like growth factor protects pericytes from injury

BACKGROUND

We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) promotes angiogenesis and preserves mesenteric microvascular blood flow in several models of intestinal injury. The current study was designed to evaluate the effect of HB-EGF on pericytes, since these cells function to regulate capillary blood flow and new capillary growth.

MATERIALS AND METHODS

C3H/10T1/2 mouse mesenchymal cells were differentiated into pericyte-like cells in vitro using transforming growth factor-β1 (TGF-β1). In addition, primary pericyte cultures were established from rat brain. The effect of HB-EGF on pericyte proliferation was assessed. In addition, cells were stressed by exposure to anoxia, and apoptosis determined. In vivo, we examined the effect of HB-EGF on pericytes in a model of intestinal I/R injury based on superior mesenteric artery occlusion (SMAO) in mice.

RESULTS

Differentiated C3H/10T1/2 cells (pericyte-like cells) demonstrated morphologic characteristics of pericytes, and expressed pericyte specific markers. Addition of HB-EGF led to significant cell proliferation in differentiated pericyte-like cells, even under conditions of anoxic stress. Addition of the EGF receptor inhibitor AG 1478 led to complete inhibition of the proliferative effects of HB-EGF on pericyte-like cells. In addition, HB-EGF protected pericyte-like cells from anoxia-induced apoptosis. In addition, HB-EGF promoted cell proliferation in primary pericyte cultures. In vivo, administration of HB-EGF to mice subjected to intestinal I/R injury led to protection of pericytes from injury.

CONCLUSIONS

These results suggest that HB-EGF may function as a microcirculatory blood flow regulator, at least in part, via its effects on pericytes.

Heparin-binding epidermal growth factor-like growth factor is a potent neurotrophic factor for PC12 cells

Heparin-binding epidermal growth factor EGF-like growth factor (HB-EGF) is a member of the epidermal growth factor family that is expressed in many cell types. We have previously reported the effects of HB-EGF on intestinal epithelial cells and endothelial cells after exposure to ischemia/reperfusion in vivo or anoxia/reoxygenation injury in vitro. However, the effect of HB-EGF on neuronal cells is largely unexplored. In this study, we examined the effect of HB-EGF on neurite outgrowth in pheochromocytoma (PC12) cells as well as the neuroprotective effect of HB-EGF on injured PC12 cells exposed to oxygen and glucose deprivation (OGD), which mimics ischemic conditions. We found that HB-EGF significantly promotes PC12 cell neurite outgrowth and that this effect was blocked by EGF receptor (EGFR) inhibition or mitogen-activated protein kinase (MAPK) inhibition, but not by tyrosine kinase inhibition. In the face of OGD injury, HB-EGF preserves cell viability and decreases apoptosis and LDH release in PC12 cells. HB-EGF-mediated cytoprotection was abolished by EGFR inhibition and MAPK inhibition. We conclude that HB-EGF, through its interaction with the EGF receptor, activates the MAPK signaling pathway in PC12 cells under basal or injury conditions, leading to enhanced neurite outgrowth and neuroprotection against ischemic injury.

Heparin-binding EGF-like growth factor promotes intestinal anastomotic healing

BACKGROUND

We have accumulated multiple lines of evidence supporting the ability of HB-EGF to protect the intestines from injury and to augment the healing of partial-thickness scald burns of the skin. The aim of the current study was to investigate the role of heparin-binding EGF-like growth factor (HB-EGF) in intestinal anastomotic wound healing.

MATERIALS AND METHODS

HB-EGF (-/-) knockout (KO) mice (n=42) and their HB-EGF (+/+) wild type (WT) counterparts (n=33), as well as HB-EGF transgenic (TG) mice (n=26) and their (WT) counterparts (n=27), underwent division and reanastomosis of the terminal ileum. In addition, WT mice (n=21) that received enteral HB-EGF (800 μg/kg) underwent the same operative procedure. Anastomotic bursting pressure was measured at 3 and 6 d postoperatively. Tissue sections were stained with hematoxylin and eosin to assess anastomotic healing, and Picrosirus red to assess collagen deposition. Immunohistochemistry using anti-von Willebrand factor antibodies was performed to assess angiogenesis. Complications and mortality were also recorded.

RESULTS

HB-EGF KO mice had significantly lower bursting pressures, lower healing scores, higher mortality, and higher complication rates postoperatively compared with WT mice. Collagen deposition and angiogenesis were significantly decreased in KO mice compared with WT mice. Conversely, HB-EGF TG mice had increased anastomotic bursting pressure, higher healing scores, lower mortality, lower complication rates, increased collagen deposition, and increased angiogenesis postoperatively compared with WT mice. WT mice that received HB-EGF had increased bursting pressures compared with non-HB-EGF treated mice.

CONCLUSION

Our results demonstrate that HB-EGF is an important factor involved in the healing of intestinal anastomoses.

HB-EGF protects the lungs after intestinal ischemia/reperfusion injury

BACKGROUND

Acute respiratory distress syndrome continues to be a major source of morbidity and mortality in critically-ill patients. Heparin binding EGF-like growth factor (HB-EGF) is a biologically active protein that acts as an intestinal cytoprotective agent. We have previously demonstrated that HB-EGF protects the intestines from injury in several different animal models of intestinal injury. In the current study, we investigated the ability of HB-EGF to protect the lungs from remote organ injury after intestinal ischemia/reperfusion (I/R).

METHODS

Mice were randomly assigned to one of the following groups: (1) sham-operated; (2) sham+HB-EGF (1200 microg/kg in 0.6 mL administered by intra-luminal injection at the jejuno-ileal junction immediately after identification of the superior mesenteric artery); (3) superior mesenteric artery occlusion for 45 min followed by reperfusion for 6 h (I/R); or (4) I/R+HB-EGF (1200 microg/kg in 0.6 mL) administered 15 min after vascular occlusion. The severity of acute lung injury was determined by histology, morphometric analysis and invasive pulmonary function testing. Animal survival was evaluated using Kaplan-Meier analysis.

RESULTS

Mice subjected to intestinal I/R injury showed histologic and functional evidence of acute lung injury and decreased survival compared with sham-operated animals. Compared with mice treated with HB-EGF (I/R+HB-EGF), the I/R group had more severe acute lung injury, and decreased survival.

CONCLUSION

Our results demonstrate that HB-EGF reduces the severity of acute lung injury after intestinal I/R in mice. These data demonstrate that HB-EGF may be a potential novel systemic anti-inflammatory agent for the prevention of the systemic inflammatory response syndrome (SIRS) after intestinal injury.

Deletion of the heparin-binding epidermal growth factor-like growth factor gene increases susceptibility to necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is the leading surgical cause of death in premature infants. We have accumulated evidence supporting a role for heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) in protection of the intestines from NEC. The aim of the current study was to evaluate the effect of loss-of-function of endogenous HB-EGF on susceptibility to NEC.

METHODS

Neonatal HB-EGF((-/-)) knockout (KO) mice and their HB-EGF((+/+)) wild-type (WT) counterparts were exposed to experimental NEC. An additional group of HB-EGF KO pups were also exposed to NEC but had HB-EGF added to their formula. To examine gut barrier function, HB-EGF KO and WT pups received intragastric fluorescein isothiocyanate-labeled dextran (FITC dextran) under basal and stressed conditions, and serum FITC dextran levels were measured.

RESULTS

The WT mice had an incidence of NEC of 53%, whereas HB-EGF KO mice had a significantly increased incidence of NEC of 80% (P = .04). Importantly, administration of exogenous HB-EGF to HB-EGF KO pups significantly reduced the incidence of NEC to 45% (P = .04). Heparin-binding EGF KO mice had significantly increased intestinal permeability compared to WT mice under basal and stressed conditions.

CONCLUSIONS

Our results provide evidence that loss of the HB-EGF gene increases susceptibility to NEC and that administration of exogenous HB-EGF reverses this susceptibility.

Intestinal phenotype in mice overexpressing a heparin-binding EGF-like growth factor transgene in enterocytes

PRIMARY OBJECTIVE

Heparin-binding EGF-like growth factor (HB-EGF) protects the intestine from damage in animals. Future clinical trials of HB-EGF may involve administration of repeated doses of HB-EGF. Since HB-EGF activates EGF receptors which have been implicated in tumor development, we examined the effects of HB-EGF overexpression in the intestine.

RESEARCH DESIGN

We generated transgenic (TG) mice in which the human HB-EGF gene is driven by the villin promoter to overexpress HB-EGF along the crypt-villous axis from the duodenum to the colon.

RESULTS

HB-EGF TG mice have increased enterocyte proliferation balanced by increased enterocyte apoptosis. Despite prolonged overexpression of HB-EGF, no evidence of intestinal hyperplasia or tumor formation occurs. Although HB-EGF TG mice have no significant phenotypic alterations under basal conditions, they have increased resistance to intestinal injury.

CONCLUSIONS

Prolonged intestinal HB-EGF overexpression results in no significant phenotypic alterations under basal conditions, but confers protection against intestinal injury.

Antecedents of Bell stage III necrotizing enterocolitis

OBJECTIVE

New biopharmaceuticals hold promise for preventing or treating necrotizing enterocolitis. However, it is unclear whether any such biopharmaceutical that requires enteral administration could be administered using an 'early-treatment' paradigm. This study was undertaken to assess this issue based on data from every case of Bell stage III NEC cared for during the past 7 years at Intermountain Healthcare.

STUDY DESIGN

Patients with Bell stage III NEC were identified from electronic medical record repositories and the diagnosis was validated using operative reports. Electronic and paper records of each patient were then used to identify potential clinical and laboratory antecedents occurring within the 48 h period preceding the diagnosis of NEC.

RESULT

One hundred eighteen patients had Stage III NEC. The earliest recognized antecedents were nonspecific for NEC (apnea/bradycardia, skin mottling and irritability). These were recorded at 2.8+/-2.1, 4.5+/-3.1 and 5.4+/-3.7 (mean+/-s.d.) hours, respectively, before NEC was diagnosed. The most commonly identified gastrointestinal antecedents were blood in the stools, increased abdominal girth and elevated pre-feeding gastric residuals or emesis. These were identified 2.0+/-1.9, 2.8+/-3.1 and 4.9+/-4.0 h before NEC was recognized. Thirty-eight percent had a blood transfusion (18+/-12 h) preceding the NEC. Tachycardia, tachypnea, hypotension and diarrhea were rarely identified as antecedents and no consistent laboratory antecedents were discovered.

CONCLUSION

We judge that an 'early treatment of NEC' paradigm testing any pharmacological agent that must be administered enterally is not feasible. The first recognized antecedents of Bell stage III NEC are nonspecific for gastrointestinal pathology and insufficient time exists for dosing between the first gastrointestinal signs and placement of the gastric decompression tube.

Can we cut the incidence of necrotizing enterocolitis in half--today?

Necrotizing enterocolitis (NEC) is a common gastrointestinal emergency of neonates. Population studies estimate the incidence of NEC at between 0.3 and 2.4 per 1000 live births in the United States, with a predominance of cases among preterm neonates born at the earliest gestational ages. The disease burden of NEC includes an overall disease-specific mortality rate of 15-20%, with yet higher rates in those of earliest gestations. The NEC burden also includes an increase in hospital costs approximating $100,000/case, as well as severe late sequellae including parenteral nutrition-associated liver disease and short bowel syndrome. Differentiating NEC from other forms of acquired neonatal intestinal disease is critical to assessing the success of NEC prevention strategies. Promising new prevention strategies are now being tested; one such is prophylactic heparin-binding epidermal growth factor-like growth factor (HB-EGF) administration. However, two prevention strategies have already been shown in meta-analyses to reduce the incidence of NEC, but we speculate that these are not being fully utilized. They are; 1) implementing a written set of feeding guidelines (also called standardized feeding regimens) for newborn intensive care unit (NICU) patients, and 2) implementing programs to increase the availability of human milk for patients at risk of developing NEC.

Heparin-binding epidermal growth factor-like growth factor is essential for preservation of gut barrier function after hemorrhagic shock and resuscitation in mice

BACKGROUND

The aim of the current study was to determine the role of heparin-binding (HB) epidermal growth factor (EGF)-like growth factor as a mediator of gut barrier function after hemorrhagic shock and resuscitation (HS/R) in mice.

METHODS

HS/R was induced in HB-EGF knockout (KO) and wild-type (WT) mice. Intestinal histologic injury scores, intestinal epithelial cell apoptosis, and gut barrier function were determined. Statistical analyses were performed using linear mixed models with P<.05 considered significant.

RESULTS

All mice subjected to HS/R had significantly increased intestinal histologic injury scores, apoptosis indices, and intestinal permeability compared with mice subjected to sham operation. Compared with WT mice, HB-EGF KO mice subjected to HS/R had significantly increased histologic injury (mean injury grade, 4.5 +/- 1 vs 2.75 +/- 0.5 at 3 hours of resuscitation; P<.05), increased apoptosis indices (mean apoptosis index, 6.84 +/- 1.95 vs 3.24 +/- 1.00 at 3 hours of resuscitation; P < .05), and increased mucosal permeability (FD4 clearance 78 +/- 18.91 vs 47.75 +/- 8.06 nL/min/cm(2) at 3 hours of resuscitation; P<.05).

CONCLUSION

HB-EGF is essential for the preservation of gut barrier function after HS/R. These findings support the clinical use of HB-EGF in protection of the intestines from disease states associated with intestinal hypoperfusion injury.

Heparin-binding EGF-like growth factor increases intestinal microvascular blood flow in necrotizing enterocolitis

BACKGROUND & AIMS

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in neonates. Although the exact etiology remains unknown, decreased intestinal blood flow is believed to play a critical role. We have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF) protects the intestines from injury in a rodent model of NEC. Our current goal was to assess the effect of HB-EGF on intestinal microvascular blood flow and intestinal injury in rat pups subjected to experimental NEC.

METHODS

Newborn rat pups were subjected to stress by exposure to hypoxia, hypothermia, hypertonic feedings, and lipopolysaccharide, with some pups receiving HB-EGF (800 microg x kg(-1) x dose(-1)) added to the feeds. Control animals received breast milk. Intestinal injury was graded using a standard histologic injury scoring system. Microvascular blood flow was assessed by fluorescein isothiocyanate/dextran angiography, with fluorescent images subjected to quantification, and by scanning electron microscopy.

RESULTS

Intestinal microvascular blood flow (defined as the extent of vascular filling with fluorescein isothiocyanate/dextran) was significantly decreased in pups subjected to stress compared with breast-fed pups. Stressed pups treated with HB-EGF had significantly increased microvascular blood flow. The changes in villous microvasculature correlated with histologic injury scores, with stressed pups treated with HB-EGF showing decreased histologic injury.

CONCLUSIONS

HB-EGF significantly preserved intestinal microvascular blood flow in pups subjected to experimental NEC, indicating that HB-EGF may play a critical role in the treatment of various diseases manifested by decreased intestinal blood flow, including NEC.

Heparin-binding EGF-like growth factor is a potent dilator of terminal mesenteric arterioles

OBJECTIVE

We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) protects the intestines from multiple forms of injury via direct cytoprotective effects on the intestinal mucosa. In this study, we examined the effects of HB-EGF on the hemodynamics of intestinal arterioles, the major resistance vessels that regulate blood flow to the intestines, as an additional mechanism of HB-EGF-mediated intestinal protection.

METHODS

The hemodynamic effects of HB-EGF in rodent terminal mesenteric arterioles and human submucosal arterioles were examined ex vivo using a video dimension analyzer. Cultured human intestinal microvascular endothelial cells (HIMEC) were used to elucidate the mechanisms of HB-EGF-induced vasodilation.

RESULTS

HB-EGF significantly increased vessel diameter under conditions of increasing intraluminal pressure and increased flow rate. These HB-EGF-mediated vasodilatory effects were observed in terminal mesenteric arterioles from adult rats and 3 day old rat pups. These effects were confirmed in submucosal arterioles from human intestine. Furthermore, HB-EGF significantly reduced endothelin-1-induced mesenteric arteriolar vasoconstriction. The vasodilatory effects of HB-EGF were blocked by ET(B) receptor antagonism in adult rat arterioles, and also by nitric oxide synthase inhibition in rat pup and human infant arterioles. In HIMEC, HB-EGF significantly increased endothelin B (ET(B)) receptor protein expression and provoked intracellular calcium mobilization.

CONCLUSIONS

HB-EGF is a potent vasodilator of the intestinal microvasculature, further supporting its use in diseases manifested by decreased intestinal blood flow, including necrotizing enterocolitis.

Preclinical neonatal rat studies of heparin-binding EGF-like growth factor in protection of the intestines from necrotizing enterocolitis

We have previously demonstrated that enterally administered heparin-binding EGF-like growth factor (HB-EGF) produced in Escherichia coli decreases the incidence and severity of intestinal injury in a neonatal rat model of necrotizing enterocolitis (NEC). In preparation for upcoming human clinical trials, large-scale production of HB-EGF according to Good Manufacturing Practice (GMP) has been successfully accomplished using a Pichia pastoris yeast system. The current studies used a neonatal rat model of NEC to elucidate several important preclinical characteristics of HB-EGF therapy. We found that enteral administration of HB-EGF (800 microg/kg/dose) four times a day effectively reduced the incidence and severity of NEC, that Pichia-derived HB-EGF was not significantly different from E. coli-derived HB-EGF in preventing NEC, that EGF was not superior to HB-EGF in preventing NEC, and that prophylactic administration of HB-EGF added to formula starting with the first feed or 12 h later significantly reduced the incidence of NEC, with no change in the incidence of NEC noted if HB-EGF was added to the formula starting 24, 48, or 72 h after birth. Thus, large-scale production of GMP-grade HB-EGF in Pichia pastoris yeast produces a biologically active molecule suitable for human clinical trials.

Gastric outlet obstruction due to adenocarcinoma in a patient with Ataxia-Telangiectasia syndrome: a case report and review of the literature

Background

Ataxia-Telangiectasia syndrome is characterized by progressive cerebellar dysfunction, conjuctival and cutaneous telangiectasias, severe immune deficiencies, premature aging and predisposition to cancer. Clinical and radiographic evaluation for malignancy in ataxia-telangiectasia patients is usually atypical, leading to delays in diagnosis.

Case presentation

We report the case of a 20 year old ataxia-telangiectasia patient with gastric adenocarcinoma that presented as complete gastric outlet obstruction.

Conclusion

A literature search of adenocarcinoma associated with ataxia-telangiectasia revealed 6 cases. All patients presented with non-specific gastrointestinal complaints suggestive of ulcer disease. Although there was no correlation between immunoglobulin levels and development of gastric adenocarcinoma, the presence of chronic gastritis and intestinal metaplasia seem to lead to the development of gastric adenocarcinoma. One should consider adenocarcinoma in any patient with ataxia-telangiectasia who presents with non-specific gastrointestinal complaints, since this can lead to earlier diagnosis.

Myectomy-myotomy for long segment Hirschsprung's disease in a patient with Haddad syndrome

Hirschsprung's disease is a rare entity with an incidence of 1 in 5000 live born infants. Long segment Hirschsprung's disease occurs in approximately 5% to 10% of this patient population and is defined as a transition zone proximal to the sigmoid colon (Bodian M, Carter CO, Ward BC. Hirschsprung's disease. Lancet. 1951;1:302-309). The association of congenital central hypoventilation syndrome (also known as Ondine's curse) and Hirschsprung's disease is termed Haddad syndrome.

HB-EGF stimulates eNOS expression and nitric oxide production and promotes eNOS dependent angiogenesis

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the epidermal growth factor (EGF) family of ligands that is expressed by many cell types including endothelial cells. We have previously shown that HB-EGF stimulates angiogenesis in vitro in human umbilical vein endothelial cells (HUVEC). Nitric oxide (NO) derived from endothelial nitric oxide synthase (eNOS) is an important regulator of angiogenesis. However, the role of HB-EGF in regulation of eNOS has not yet been investigated. Whether HB-EGF-induced endothelial cell migration and vascular network formation are mediated via production of NO from eNOS is also unknown. To address these questions, we stimulated HUVEC with HB-EGF and evaluated the expression of eNOS at the mRNA and protein levels. HB-EGF significantly upregulated expression of eNOS mRNA, stimulated eNOS protein production, and increased NO release from HUVEC. HB-EGF phosphorylated eNOS in a phosphatidylinositol 3-kinase (PI3K) dependent fashion, and stimulated in vitro angiogenesis. eNOS siRNA inhibited HB-EGF-stimulated HUVEC migration in a scratch assay. NG-nitro-L-arginine-methyl-ester (L-NAME) and L-N5-(1-lminoethyl)ornithine,dihydochloride (L-NIO) (specific inhibitors of eNOS) also abolished HB-EGF-induced HUVEC migration and angiogenesis. More importantly, we found that HB-EGF also promotes angiogenesis in vivo in the Marigel plug assay. Lastly, inhibition of the p38 MAPK pathway enhanced HB-EGF-induced EC migration and angiogenesis. We conclude that HB-EGF, through its interaction with EGF receptors (EGFR), stimulates eNOS activation and NO production via a PI3K-dependent pathway. Thus, activation of eNOS appears to be one of the key signaling pathways necessary for HB-EGF mediated angiogenesis. These novel findings highlight an important role for HB-EGF as a regulator of endothelial cell function.

Inversion appendectomy acting as a lead point for intussusception

A case of ileocecal intussusception following inversion appendectomy during a Ladd's procedure for malrotation is presented. In this case, the inverted ischemic appendiceal remnant was presumed to have acted as the leadpoint for the intussusception. The advantages and complications of inversion appendectomy, along with technical considerations are discussed.