Inhibition of NF-kappa B activation and its target genes by heparin-binding epidermal growth factor-like growth factor

Newly Identified Deficiencies in the Multiple Sclerosis Central Nervous System and Their Impact on the Remyelination Failure

The pathogenesis of multiple sclerosis (MS) remains enigmatic and controversial. Myelin sheaths in the central nervous system (CNS) insulate axons and allow saltatory nerve conduction. MS brings about the destruction of myelin sheaths and the myelin-producing oligodendrocytes (ODCs). The conundrum of remyelination failure is, therefore, crucial in MS. In this review, the roles of epidermal growth factor (EGF), normal prions, and cobalamin in CNS myelinogenesis are briefly summarized. Thereafter, some findings of other authors and ourselves on MS and MS-like models are recapitulated, because they have shown that: (a) EGF is significantly decreased in the CNS of living or deceased MS patients; (b) its repeated administration to mice in various MS-models prevents demyelination and inflammatory reaction; (c) as was the case for EGF, normal prion levels are decreased in the MS CNS, with a strong correspondence between liquid and tissue levels; and (d) MS cobalamin levels are increased in the cerebrospinal fluid, but decreased in the spinal cord. In fact, no remyelination can occur in MS if these molecules (essential for any form of CNS myelination) are lacking. Lastly, other non-immunological MS abnormalities are reviewed. Together, these results have led to a critical reassessment of MS pathogenesis, partly because EGF has little or no role in immunology.

Protective Functions of Reactive Astrocytes Following Central Nervous System Insult

Astrocytes play important roles in numerous central nervous system disorders including autoimmune inflammatory, hypoxic, and degenerative diseases such as Multiple Sclerosis, ischemic stroke, and Alzheimer’s disease. Depending on the spatial and temporal context, activated astrocytes may contribute to the pathogenesis, progression, and recovery of disease. Recent progress in the dissection of transcriptional responses to varying forms of central nervous system insult has shed light on the mechanisms that govern the complexity of reactive astrocyte functions. While a large body of research focuses on the pathogenic effects of reactive astrocytes, little is known about how they limit inflammation and contribute to tissue regeneration. However, these protective astrocyte pathways might be of relevance for the understanding of the underlying pathology in disease and may lead to novel targeted approaches to treat autoimmune inflammatory and degenerative disorders of the central nervous system. In this review article, we have revisited the emerging concept of protective astrocyte functions and discuss their role in the recovery from inflammatory and ischemic disease as well as their role in degenerative disorders. Focusing on soluble astrocyte derived mediators, we aggregate the existing knowledge on astrocyte functions in the maintenance of homeostasis as well as their reparative and tissue-protective function after acute lesions and in neurodegenerative disorders. Finally, we give an outlook of how these mediators may guide future therapeutic strategies to tackle yet untreatable disorders of the central nervous system.

Studies on the Mechanisms of Anti-Inflammatory Activity of Heparin- and Hyaluronan-Containing Multilayer Coatings-Targeting NF-κB Signalling Pathway

The use of implants can be hampered by chronic inflammatory reactions, which may result in failure of the implanted device. To prevent such an outcome, the present study examines the anti-inflammatory properties of surface coatings made of either hyaluronic acid (HA) or heparin (Hep) in combination with chitosan (Chi) prepared as multilayers through the layer-by-layer (LbL) technique. The properties of glycosaminoglycan (GAG)-modified surfaces were characterized in terms of surface topography, thickness and wettability. Results showed a higher thickness and hydrophilicity after multilayer formation compared to poly (ethylene imine) control samples. Moreover, multilayers containing either HA or Hep dampened the inflammatory response visible by reduced adhesion, formation of multinucleated giant cells (MNGCs) and IL-1β release, which was studied using THP-1 derived macrophages. Furthermore, investigations regarding the mechanism of anti-inflammatory activity of GAG were focused on nuclear transcription factor-кB (NF-κB)-related signal transduction. Immunofluorescence staining of the p65 subunit of NF-κB and immunoblotting were performed that showed a significant decrease in NF-κB level in macrophages on GAG-based multilayers. Additionally, the association of FITC-labelled GAG was evaluated by confocal laser scanning microscopy and flow cytometry showing that macrophages were able to associate with and take up HA and Hep. Overall, the Hep-based multilayers demonstrated the most suppressive effect making this system most promising to control macrophage activation after implantation of medical devices. The results provide an insight on the anti-inflammatory effects of GAG not only based on their physicochemical properties, but also related to their mechanism of action toward NF-κB signal transduction.

Impact of novel N-aryl piperamide NO donors on NF-κB translocation in neuroinflammation: rational drug-designing synthesis and biological evaluation

NO donor drugs showed a significant therapeutic effect in the treatment of many diseases, such as arteriopathies, various acute and chronic inflammatory conditions, and several degenerative diseases. NO-releasing anti-inflammatory drugs are the prototypes of a novel class of compounds, combining the pharmacological activities of anti-inflammatory and anti-nociceptive of drugs with those of NO, thus possessing potential therapeutic applications in a great variety of diseases. In this study, we designed and predicted biological activity by targeting cyclooxygenase type 2 (COX-2) and NF-κB subunits and pharmacological profiling along with toxicity predictions of various N-aryl piperamides linked via an ester bond to a spacer that is bound to a NO-releasing moiety (-ONO2). The result of absorption, distribution, metabolism and excretion and Docking studies indicated that among 51 designed molecules PA-3′K showed the best binding potential in both the substrate and inhibitory binding pocket of the COX-2 enzyme with affinity values of –9.33 and –5.12 for PDB ID 1CVU and 3LN1, respectively, thereby having the potential to be developed as a therapeutic agent. The results of cell viabilities indicated that PA-3′k possesses the best cell viability property with respect to its dose (17.33 ng/ml), with 67.76% and 67.93% viable cells for CHME3 and SVG cell lines, respectively.

Antisense miR-132 blockade via the AChE-R splice variant mitigates cortical inflammation

MicroRNA (miR)-132 brain-to-body messages suppress inflammation by targeting acetylcholinesterase (AChE), but the target specificity of 3'-AChE splice variants and the signaling pathways involved remain unknown. Using surface plasmon resonance (SPR), we identified preferential miR-132 targeting of soluble AChE-R over synaptic-bound AChE-S, potentiating miR-132-mediated brain and body cholinergic suppression of pro-inflammatory cytokines. Inversely, bacterial lipopolysaccharide (LPS) reduced multiple miR-132 targets, suppressed AChE-S more than AChE-R and elevated inflammatory hallmarks. Furthermore, blockade of peripheral miR-132 by chemically protected AM132 antisense oligonucleotide elevated muscle AChE-R 10-fold over AChE-S, and cortical miRNA-sequencing demonstrated inverse brain changes by AM132 and LPS in immune-related miRs and neurotransmission and cholinergic signaling pathways. In neuromuscular junctions, AM132 co-elevated the nicotinic acetylcholine receptor and AChE, re-balancing neurotransmission and reaching mild muscle incoordination. Our findings demonstrate preferential miR-132-induced modulation of AChE-R which ignites bidirectional brain and body anti-inflammatory regulation, underscoring splice-variant miR-132 specificity as a new complexity level in inflammatory surveillance.

Intestinal barrier dysfunction: implications for chronic inflammatory conditions of the bowel

The intestinal epithelium of adult humans acts as a differentially permeable barrier that separates the potentially harmful contents of the lumen from the underlying tissues. Any dysfunction of this boundary layer that disturbs the homeostatic equilibrium between the internal and external environments may initiate and sustain a biochemical cascade that results in inflammation of the intestine. Key to such dysfunction are genetic, microbial and other environmental factors that, singularly or in combination, result in chronic inflammation that is symptomatic of inflammatory bowel disease (IBD). The aim of the present review is to assess the scientific evidence to support the hypothesis that defective transepithelial transport mechanisms and the heightened absorption of intact antigenic proinflammatory oligopeptides are important contributing factors in the pathogenesis of IBD.

Cypermethrin Stimulates GSK3β-Dependent Aβ and p-tau Proteins and Cognitive Loss in Young Rats: Reduced HB-EGF Signaling and Downstream Neuroinflammation as Critical Regulators

Pesticide exposure is recognized as a risk factor for Alzheimer's disease (AD). We investigated early signs of AD-like pathology upon exposure to a pyrethroid pesticide, cypermethrin, reported to impair neurodevelopment. We treated weanling rats with cypermethrin (10 and 25 mg/kg) and detected dose-dependent increase in the key proteins of AD, amyloid beta (Aβ), and phospho-tau, in frontal cortex and hippocampus as early as postnatal day 45. Upregulation of Aβ pathway involved an increase in amyloid precursor protein (APP) and its pro-amyloidogenic processing through beta-secretase (BACE) and gamma-secretase. Tau pathway entailed elevation in tau and glycogen-synthase kinase-3-beta (GSK3β)-dependent, phospho-tau. GSK3β emerged as a molecular link between the two pathways, evident from reduction in phospho-tau as well as BACE upon treating GSK3β inhibitor, lithium chloride. Exploring the mechanism revealed an attenuated heparin-binding epidermal growth factor (HB-EGF) signaling and downstream astrogliosis-mediated neuroinflammation to be responsible for inducing Aβ and phospho-tau. Cypermethrin caused a proximal reduction in HB-EGF, which promoted astrocytic nuclear factor kappa B signaling and astroglial activation close to Aβ and phospho-tau. Glial activation stimulated generation of interleukin-1 (IL-1), which upregulated GSK3β, and APP and tau as well, resulting in co-localization of Aβ and phospho-tau with IL-1 receptor. Intracerebral insertion of exogenous HB-EGF restored its own signaling and suppressed neuroinflammation and thereby Aβ and phospho-tau in cypermethrin-exposed rats, proving a central role of reduced HB-EGF signaling in cypermethrin-mediated neurodegeneration. Furthermore, cypermethrin stimulated cognitive impairments, which could be prevented by exogenous HB-EGF. Our data demonstrate that cypermethrin induces premature upregulation of GSK3β-dependent Aβ and tau pathways, where HB-EGF signaling and neuroinflammation serve as essential regulators.

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.

Transcriptome analysis of human peripheral blood mononuclear cells exposed to Lassa virus and to the attenuated Mopeia/Lassa reassortant 29 (ML29), a vaccine candidate

Lassa virus (LASV) is the causative agent of Lassa Fever and is responsible for several hundred thousand infections and thousands of deaths annually in West Africa. LASV and the non-pathogenic Mopeia virus (MOPV) are both rodent-borne African arenaviruses. A live attenuated reassortant of MOPV and LASV, designated ML29, protects rodents and primates from LASV challenge and appears to be more attenuated than MOPV. To gain better insight into LASV-induced pathology and mechanism of attenuation we performed gene expression profiling in human peripheral blood mononuclear cells (PBMC) exposed to LASV and the vaccine candidate ML29. PBMC from healthy human subjects were exposed to either LASV or ML29. Although most PBMC are non-permissive for virus replication, they remain susceptible to signal transduction by virus particles. Total RNA was extracted and global gene expression was evaluated during the first 24 hours using high-density microarrays. Results were validated using RT-PCR, flow cytometry and ELISA. LASV and ML29 elicited differential expression of interferon-stimulated genes (ISG), as well as genes involved in apoptosis, NF-kB signaling and the coagulation pathways. These genes could eventually serve as biomarkers to predict disease outcomes. The remarkable differential expression of thrombomodulin, a key regulator of inflammation and coagulation, suggests its involvement with vascular abnormalities and mortality in Lassa fever disease.

The virulent Lassa fever virus (LASV) and the non-pathogenic Mopeia virus (MOPV) infect rodents and, incidentally, people in West Africa. The mechanism of LASV damage in human beings is unclear. There is no licensed Lassa fever vaccine and therapeutic intervention is usually too late. The ML29 vaccine candidate derived from Lassa and Mopeia viruses protects rodents and primates from Lassa fever disease. Peripheral blood mononuclear cells from healthy human subjects were exposed to either LASV or ML29 in order to identify early cellular responses that could be attributed to the difference in virulence between the two viruses. Differential expression of interferon-stimulated genes as well as coagulation-related genes could lead to an explanation for Lassa fever pathogenesis and indicate protective treatments for Lassa fever disease.

Heparin-binding epidermal growth factor-like growth factor attenuates acute lung injury and multiorgan dysfunction after scald burn

BACKGROUND

Impaired gut barrier function and acute lung injury (ALI) are significant components of the multiorgan dysfunction syndrome that accompanies severe burns. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to reduce inflammation, preserve gut barrier function, and protect the lungs from acute injury in several models of intestinal injury; however, comparable effects of HB-EGF after burn injury have never been investigated. The present studies were based on the hypothesis that HB-EGF would reduce the severity of ALI and multiorgan dysfunction after scald burns in mice.

MATERIALS AND METHODS

Mice were randomized to sham, burn (25% of total body surface area with full thickness dorsal scald), and burn + HB-EGF groups. The HB-EGF group was pretreated with two enteral doses of HB-EGF (1200 μg/kg/dose). Mice were resuscitated after injury and sacrificed at 8 h later. Their lungs were harvested for determination of pulmonary myeloperoxidase activity, wet:dry ratios, and terminal deoxynucleotidyl transferase dUTP nick end label and cleaved caspase 3 immunohistochemistry. Lung function was assessed using the SCIREQ Flexivent. Splenic apoptosis was quantified by Western blot for cleaved caspase 3, and intestinal permeability was measured using the everted gut sac method.

RESULTS

Mice subjected to scald burn injury had increased lung myeloperoxidase levels, increased pulmonary and splenic apoptosis, elevated airway resistance and bronchial reactivity, and increased intestinal permeability compared with sham mice. These abnormalities were significantly attenuated in mice that were subjected to scald burn injury but treated with enteral HB-EGF.

CONCLUSIONS

These data suggest that HB-EGF protects mice from ALI after scald burn and attenuates the severity of postburn multiorgan dysfunction.

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 (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.

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.

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.

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.

PAR2 triggers IL-8 release via MEK/ERK and PI3-kinase/Akt pathways in GI epithelial cells

Proteinase-activated receptor-2 (PAR2) plays pro-inflammatory roles in many organs including the gastrointestinal (GI) tract. To clarify the downstream pro-inflammatory signaling of PAR2 in the GI tract, we examined interleukin-8 (IL-8) release and the underlying cellular signaling following PAR2 stimulation in human colorectal cancer-derived HCT-15 cells and human gastric adenocarcinoma-derived MKN-45 cells. A PAR2-activating peptide, but not a PAR2-inactive scrambled peptide or a PAR1- activating peptide, caused IL-8 release in these GI epithelial cells. The PAR2-triggered IL-8 release was suppressed by inhibitors of MEK (U0126) or PI3-kinase (LY294002), and PAR2 stimulation indeed activated the downstream kinases, ERK and Akt. U0126 blocked the phosphorylation of ERK, but not Akt, and LY294002 blocked the phosphorylation of Akt, but not ERK. Together, PAR2 triggers IL-8 release via two independent signaling pathways, MEK/ERK and PI3-kinase/Akt, suggesting a role of PAR2 as a pro-inflammatory receptor in the GI tract.

Flavonoids protect against cytokine-induced pancreatic beta-cell damage through suppression of nuclear factor kappaB activation

OBJECTIVES

In the past few decades, the use of natural compounds, such as flavonoids, as anti-inflammatory agents has gained much attention. Our current study focuses on the preventive effects of quercetin, apigenin, and luteolin on cytokine-induced beta-cell damage.

METHODS

Pancreatic beta-cells or islets were treated with cytokine mixtures in the presence or absence of flavonoids and the inhibitory effect of flavonoids against cytokine toxicity was determined.

RESULTS

Treatment of RINm5F (RIN) rat insulinoma cells with interleukin 1beta (IL-1beta) and interferon gamma (IFN-gamma) induced cell damage. Quercetin, apigenin, and luteolin completely protected against IL-1beta- and IFN-gamma-mediated cytotoxicity in RIN cells. Incubation with quercetin, apigenin, and luteolin resulted in a significant reduction in IL-1beta- and IFN-gamma-induced nitric oxide production, a finding that correlated well with reduced levels of the inducible form of NO synthase messenger RNA and protein. The molecular mechanism by which quercetin, apigenin, and luteolin inhibited inducible NO synthase gene expression appeared to involve the inhibition of nuclear factor kappaB (NF-kappaB) activation. The IL-1beta- and IFN-gamma-stimulated RIN cells showed increases in NF-kappaB binding activity, p50 and p65 subunit levels in nucleus, and IkappaB alpha degradation in cytosol compared with unstimulated cells. Quercetin, apigenin, and luteolin also prevented IL-1beta- and IFN-gamma-mediated inhibition of insulin secretion.

CONCLUSION

Quercetin, apigenin, and luteolin inhibited cytotoxicity in RIN cells and attenuated the decrease of glucose-stimulated insulin secretion in islets by IL-1beta and IFN-gamma.

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

BACKGROUND

Hyperadhesiveness of neutrophils (PMN) to vascular endothelial cells (EC) followed by neutrophil transendothelial migration play important roles in the initiation of ischemia/reperfusion (I/R)-mediated injury. We investigated whether the ability of heparin-binding EGF-like growth factor (HB-EGF) to decrease intestinal injury after intestinal I/R is mediated, in part, by its ability to affect PMN-EC interactions and EC junctional integrity.

MATERIALS AND METHODS

Human umbilical vein EC monolayers were treated with HB-EGF (100 ng/mL) or phosphate-buffered saline followed by anoxia/reoxygenation (A/R). Simultaneously, labeled human PMN were treated with HB-EGF or phosphate-buffered saline and then co-incubated with EC for determination of PMN-EC adherence and PMN transendothelial migration. EC junctional integrity was also determined.

RESULTS

PMN-EC adhesion increased after exposure of EC to A/R compared to EC exposed to normoxia (87% versus 64% binding, P < 0.05, Wilcoxon rank sum test). A/R-induced PMN-EC hyperadherence was significantly decreased by treatment of PMN with HB-EGF compared to nontreated cells (51% versus 87% binding, P < 0.05). HB-EGF significantly decreased PMN transendothelial migration and also augmented EC tight junctional integrity after A/R.

CONCLUSIONS

HB-EGF significantly reduces A/R-induced PMN-EC adhesion and PMN transendothelial migration and augments junctional integrity in vitro. Thus, HB-EGF acts not only as a potent cytoprotective agent for the intestine, but as an anti-inflammatory agent as well.

Heparin-binding EGF-like growth factor decreases inflammatory cytokine expression after intestinal ischemia/reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury is believed to be the major initiator of the systemic inflammatory response syndrome. As a result of intestinal I/R, the gut becomes a major source of inflammatory cytokine production. We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) is cytoprotective after intestinal I/R and down-regulates pro-inflammatory cytokine production in vitro. We now examine the effects of HB-EGF on pro-inflammatory cytokine expression in vivo.

MATERIALS AND METHODS

Rats were randomized into three groups: sham-operated, superior mesenteric artery occlusion (SMAO) for 90 min followed by 8 h of reperfusion (I/R), and I/R with intraluminal administration of HB-EGF 25 min after the initiation of ischemia (I/R + HB-EGF). Serum was drawn at 2, 4, 6, and 8 h post reperfusion for determination of cytokine protein levels using a bioplex suspension array system. Additional animals underwent the same ischemic protocol followed by 30 and 60 min of reperfusion with harvesting of ileal mucosa. Ileal pro-inflammatory cytokine gene expression was determined using reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for TNF-alpha, IL-6, and IL-1beta.

RESULTS

HB-EGF decreased TNF-alpha, IL-6, and IL-1beta serum protein levels at 4, 6, and 8 h after intestinal I/R injury. In addition, HB-EGF decreased local intestinal mucosal mRNA expression of TNF-alpha, IL-6, and IL-1beta 30 and 60 min after intestinal injury.

CONCLUSIONS

We conclude that pro-inflammatory cytokine expression is increased both locally and in the systemic circulation after intestinal I/R and that the administration of HB-EGF significantly reduces intestinal I/R-induced pro-inflammatory cytokine expression in vivo.

Adiponectin deficiency protects mice from chemically induced colonic inflammation

BACKGROUND & AIMS

Adiponectin (APN) is an adipokine that regulates insulin sensitivity and is anti-inflammatory in atherosclerosis. The goal of this study was to investigate the role of APN in intestinal inflammation.

METHODS

APN knockout (KO) mice and their wild-type (WT) littermates received dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) to induce intestinal inflammation. Clinical and histologic scores and proliferation of epithelial cells were assessed. Cytokines and APN levels were measured. Expression of APN and heparin binding epidermal growth factor (HB-EGF) was analyzed by immunohistochemistry. Expression of APN and its receptors, HB-EGF, and basic fibroblast growth factor (bFGF) messenger RNA was assessed by reverse-transcription polymerase chain reaction. Association of serum APN with HB-EGF and bFGF was studied by coimmunoprecipitation.

RESULTS

APN KO mice are protected from chemically induced colitis; administration of APN restores inflammation. APN is expressed in the colon, luminal APN associates with colonic epithelial cells. In vitro, APN increases production of proinflammatory cytokines from colonic tissue. Expression of colonic APN overlaps with that of bFGF and HB-EGF, which play a protective role in colitis. Circulating APN binds to bFGF and HB-EGF, likely inhibiting their protective activity. Inhibition of EGF receptor signaling, which is required for biologic activity of HB-EGF, restores inflammation in APN KO mice.

CONCLUSIONS

APN deficiency is associated with protection from chemically induced colitis. APN exerts proinflammatory activities in the colon by inducing production of proinflammatory cytokines and inhibiting bioactivity of protective growth factors. Thus, in colitis, APN exerts an opposite role compared with atherosclerosis.

Heparin-binding epidermal growth factor-like growth factor reduces intestinal apoptosis in neonatal rats with necrotizing enterocolitis

PURPOSE

We have previously demonstrated that enterally administered heparin-binding epidermal growth factor-like growth factor (HB-EGF) decreases the incidence and severity of necrotizing enterocolitis (NEC) in a neonatal rat model. Because apoptosis contributes to gut barrier failure in this model, the aim of this study was to investigate the effect of HB-EGF on apoptosis during the development of NEC.

METHODS

NEC was induced in neonatal rats by exposure to hypoxia, hypothermia, hypertonic formula feeding (HHHTF) plus enteral administration of lipopolysaccharide (LPS). Fifty-one neonatal rats were randomly divided into the following groups: (1) breast-fed (BF), (2) HHHTF + LPS, and (3) HHHTF + LPS with HB-EGF (600 microg/kg) added to the formula. NEC was evaluated using a standard histological scoring system. Apoptotic cells in intestinal tissues were detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) and by active caspase 3 immunohistochemical staining.

RESULTS

The incidence of NEC in the HHHTF + LPS group was higher than that in the BF group (65% vs 0%, P < .05). With administration of HB-EGF, the incidence of NEC significantly decreased to 23.8% (P < .05). The median TUNEL and active caspase 3 scores in the HHHTF + LPS group were higher than those in the BF group (1.9 vs 0.9 and 1.75 vs 0.6, respectively, P < .05). The median TUNEL and active caspase 3 scores were significantly decreased in the HHHTF + LPS + HB-EGF group compared with the HHHTF + LPS group (1.24 vs 1.9 and 1.0 vs 1.75, respectively, P < .05).

CONCLUSION

HB-EGF reduces the incidence of NEC in a neonatal rat model in part by decreasing apoptosis. These results support the use of HB-EGF-based clinical regimens for the treatment of NEC.

Heparin-binding epidermal growth factor-like growth factor inhibits cytokine-induced NF-kappa B activation and nitric oxide production via activation of the phosphatidylinositol 3-kinase pathway

NO produced by inducible NO synthase (iNOS) has been implicated in various pathophysiological processes including inflammation. Therefore, inhibitors of NO synthesis or iNOS gene expression have been considered as potential anti-inflammatory agents. We have previously demonstrated that heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) decreases proinflammatory cytokine IL-8 and NO production in cytokine-stimulated intestinal epithelial cells by interfering with the NF-kappaB signaling pathway. However, the upstream signaling mechanisms involved in these responses have not yet been defined. In this report, we show that in intestinal epithelial cells, HB-EGF triggered PI3K-dependent phosphorylation of Akt. Inhibition of PI3K reversed the ability of HB-EGF to block NF-kappaB activation, expression of iNOS, and NO production. Small interfering RNA of PI3K also reversed the inhibitory effect of HB-EGF on iNOS expression. Alternatively, transient expression of constitutively active PI3K decreased NO production by approximately 2-fold more than treatment with HB-EGF alone. This PI3K effect was HB-EGF dependent. Thus, activation of PI3K is essential but not sufficient for decreased NO synthesis. PI3K and HB-EGF act synergistically to decrease NO synthesis. Neither overexpression or inhibition of MEK, Ras, or Akt affected HB-EGF-mediated inhibition of NF-kappaB activation. These data demonstrate that HB-EGF decreases proinflammatory cytokine-stimulated NF-kappaB activation and NO production via activation of the PI3K signaling pathway. These results also suggest that inhibition of NF-kappaB and activation of the PI3K-dependent signaling cascade by HB-EGF may represent key signals responsible for the anti-inflammatory effects of HB-EGF.

Heparin-binding EGF-like growth factor (HB-EGF) and necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common and devastating gastrointestinal disease that occurs predominantly in premature infants. Despite various advances in management, the mortality of this disease remains high. During the last decade, studies from our laboratory have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the epidermal growth factor (EGF) family, can protect intestinal epithelial cells (IEC) from various forms of injury in vitro. Furthermore, we have used both an intestinal I/R injury model in adult rats, and a neonatal rat pup model of NEC, to show that HB-EGF can protect the intestines from injury. On administration of HB-EGF in the neonatal rat model, the incidence of NEC is reduced from 65% to 27.3% (P < 0.05), and the histological injury score is decreased from 2 to 1.1 (P < 0.05). In addition, the survival rate is increased from 25% to 63.6% and the survival time extended from 59 hours to 73 hours (P < 0.05). In addition, using human specimens from newborns undergoing bowel resection for NEC, we found that the expression of endogenous HB-EGF mRNA in normal areas of the intestine at the resection margins was higher than that of the intestine afflicted with acute NEC. Endogenous HB-EGF may be involved in epithelial cell repair, proliferation, and regeneration during recovery from injury. Exogenous administration of HB-EGF potentiates recovery from intestinal injury in vitro and in vivo. Taken together, these results support a potential therapeutic role for HB-EGF in the treatment of NEC in the future.

Positive and negative regulation of EAAT2 by NF-kappaB: a role for N-myc in TNFalpha-controlled repression

The glutamate transporter gene, EAAT2/GLT-1, is induced by epidermal growth factor (EGF) and downregulated by tumor necrosis factor alpha (TNFalpha). While TNFalpha is generally recognized as a positive regulator of NF-kappaB-dependent gene expression, its ability to control transcriptional repression is not well characterized. Additionally, the regulation of NF-kappaB by EGF is poorly understood. Herein, we demonstrate that both TNFalpha-mediated repression and EGF-mediated activation of EAAT2 expression require NF-kappaB. We show that EGF activates NF-kappaB independently of signaling to IkappaB. Furthermore, TNFalpha can abrogate IKKbeta- and p65-mediated activation of EAAT2. Our results suggest that NF-kappaB can intrinsically activate EAAT2 and that TNFalpha mediates repression through a distinct pathway also requiring NF-kappaB. Consistently, we find that N-myc is recruited to the EAAT2 promoter with TNFalpha and that N-myc-binding sites are required for TNFalpha-mediated repression. Moreover, N-myc overexpression inhibits both basal and p65-induced activation of EAAT2. Our data highlight the remarkable specificity of NF-kappaB activity to regulate gene expression in response to diverse cellular signals and have implications for glutamate homeostasis and neurodegenerative disease.

From mice to humans: identification of commonly deregulated genes in mammary cancer via comparative SAGE studies

Genetically engineered mouse mammary cancer models have been used over the years as systems to study human breast cancer. However, much controversy exists on the utility of such models as valid equivalents to the human cancer condition. To perform an interspecies gene expression comparative study in breast cancer we used a mouse model that most closely resembles human breast carcinogenesis. This system relies on the transplant of p53 null mouse mammary epithelial cells into the cleared mammary fat pads of syngeneic hosts. Serial analysis of gene expression (SAGE) was used to obtain gene expression profiles of normal and tumor samples from this mouse mammary cancer model (>300,000 mouse mammary-specific tags). The resulting mouse data were compared with 25 of our human breast cancer SAGE libraries (>2.5 million human breast-specific tags). We observed significant similarities in the deregulation of specific genes and gene families when comparing mouse with human breast cancer SAGE data. A total of 72 transcripts were identified as commonly deregulated in both species. We observed a systematic and significant down-regulation in all of the tumors from both species of various cytokines, including CXCL1 (GRO1), LIF, interleukin 6, and CCL2. All of the mouse and most human mammary tumors also displayed decreased expression of genes known to inhibit cell proliferation, including NFKBIA (IKBalpha), GADD45B, and CDKN1A (p21); transcription-related genes such as CEBP, JUN, JUNB, and ELF1; and apoptosis-related transcripts such as IER3 and GADD34/PPP1R15A. Examples of overexpressed transcripts in tumors from both species include proliferation-related genes such as CCND1, CKS1B, and STMN1 (oncoprotein 18); and genes related to other functions such as SEPW1, SDFR1, DNCI2, and SP110. Importantly, abnormal expression of several of these genes has not been associated previously with breast cancer. The consistency of these observations was validated in independent mouse and human mammary cancer sets. This is the first interspecies comparison of mammary cancer gene expression profiles. The comparative analysis of mouse and human SAGE mammary cancer data validates this p53 null mouse tumor model as a useful system closely resembling human breast cancer development and progression. More importantly, these studies are allowing us to identify relevant biomarkers of potential use in human studies while leading to a better understanding of specific mechanisms of human breast carcinogenesis.