Heparin-Binding EGF-like Growth Factor Decreases Neutrophil–Endothelial Cell Interactions

New Epidermal-Growth-Factor-Related Insights Into the Pathogenesis of Multiple Sclerosis: Is It Also Epistemology?

Recent findings showing that epidermal growth factor (EGF) is significantly decreased in the cerebrospinal fluid (CSF) and spinal cord (SC) of living or deceased multiple sclerosis (MS) patients, and that its repeated administration to rodents with chemically- or virally-induced demyelination of the central nervous system (CNS) or experimental allergic encephalomyelitis (EAE) prevents demyelination and inflammatory reactions in the CNS, have led to a critical reassessment of the MS pathogenesis, partly because EGF is considered to have little or no role in immunology. EGF is the only myelinotrophic factor that has been tested in the CSF and spinal cord of MS patients, and it has been shown there is a good correspondence between liquid and tissue levels. This review: (a) briefly summarises the positive EGF effects on neural stem cells, oligodendrocyte cell lineage, and astrocytes in order to explain, at least in part, the biological basis of the myelin loss and remyelination failure in MS; and (b) after a short analysis of the evolution of the principle of cause-effect in the history of Western philosophy, highlights the lack of any experimental immune-, toxin-, or virus-mediated model that precisely reproduces the histopathological features and “clinical” symptoms of MS, thus underlining the inapplicability of Claude Bernard's crucial sequence of “observation, hypothesis, and hypothesis testing.” This is followed by a discussion of most of the putative non-immunologically-linked points of MS pathogenesis (abnormalities in myelinotrophic factor CSF levels, oligodendrocytes (ODCs), astrocytes, extracellular matrix, and epigenetics) on the basis of Popper's falsification principle, and the suggestion that autoimmunity and phologosis reactions (surely the most devasting consequences of the disease) are probably the last links in a chain of events that trigger the reactions. As it is likely that there is a lack of other myelinotrophic growth factors because myelinogenesis is controlled by various CNS and extra-CNS growth factors and other molecules within and outside ODCs, further studies are needed to investigate the role of non-immunological molecules at the time of the onset of the disease. In the words of Galilei, the human mind should be prepared to understand what nature has created.

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.

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.

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.

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.

Epithelial to mesenchymal transformation in tubular epithelial cells undergoing anoxia

AIM

Epithelial-mesenchymal transformation (EMT) has been proved to be a critical event in fibrogenesis of renal allografts. This study sought to determine whether anoxia could induce EMT from tubular epithelial cells (TEC).

METHODS

Rat TEC-line (NRK-52E) was cultured in Dulbelco's modified Eagle's medium (DMEM) without glucose under 100% N2 for 4 hours. After 6, 12, 24, 48, and 72 hours, the expressions of connective tissue growth factor (CTGF) mRNA and protein were measured by real-time RT-PCR and Western blot, respectively. Morphologic changes and cytoskeleton remodeling were observed in NRK-52E cells under laser confocal microscopy. Immunohistochemistry and flow cytometry were used to detect expression changes of E-cadherin, alpha-smooth muscle actin (SMA), types I and IV collagen, all of which are involved in TEC, EMT.

RESULTS

After stimulation by anoxia, NRK-52E cells became round and enlarged with a remodeled cytoskeleton. The expressions of CTGF mRNA and protein were upregulated after 6 hours, reaching their peak at 48 hours. The expressions of types I and IV collagen, and alpha-SMA were all upregulated except for E-cadherin.

CONCLUSIONS

Anoxia upregulated the expression of CTGF and other EMT-associated genes in NRK-52E cells.

Heparin-binding epidermal growth factor-like growth factor gene disruption is associated with delayed intestinal restitution, impaired angiogenesis, and poor survival after intestinal ischemia in mice

PURPOSE

We have demonstrated that administration of heparin-binding epidermal growth factor-like growth factor (HB-EGF) protects the intestines from injury. The aim of the current study was to evaluate the effect of HB-EGF gene disruption on intestinal restitution, angiogenesis, and long-term survival after intestinal ischemia/reperfusion (I/R) injury.

METHODS

HB-EGF (-/-) and wild-type HB-EGF (+/+) littermate mice were subjected to 45 minutes of superior mesenteric artery occlusion followed by reperfusion. Functional recovery of the gut permeability barrier was evaluated with Ussing chamber studies, and microvessel density was evaluated immunohistochemically. Animal survival was evaluated using the Kaplan-Meier method.

RESULTS

Histologic damage after ischemia was significantly higher in HB-EGF (-/-) mice compared with HB-EGF (+/+) mice, associated with a significantly higher number of incompetent (nonhealed, nonresurfaced) villi indicative of delayed structural healing by restitution. HB-EGF (-/-) mice had increased intestinal permeability after intestinal I/R. HB-EGF (-/-) mice had significantly lower microvessel density at 3 and 7 days after I/R, indicating that HB-EGF gene deletion resulted in delayed onset of angiogenesis. Two-week mortality rates were significantly higher in HB-EGF (-/-) mice.

CONCLUSIONS

Endogenous HB-EGF significantly enhances healing by restitution, prolongs survival, and enhances angiogenesis in mice subjected to intestinal I/R injury. These findings support our hypothesis that HB-EGF administration may improve outcome in patients with intestinal I/R injury, including necrotizing enterocolitis.