Publications by authors named "Billy Bourke"

59 Publications

Transient elastography lacks precision in children.

Pediatr Res 2021 Aug 31. Epub 2021 Aug 31.

School of Medicine, University College Dublin, Dublin, Ireland.

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http://dx.doi.org/10.1038/s41390-021-01694-1DOI Listing
August 2021

The impact of liver disease on mortality in cystic fibrosis-A systematic review.

J Cyst Fibros 2021 Aug 8. Epub 2021 Aug 8.

School of Medicine University College Dublin, Belfield, Dublin 4, Ireland. Electronic address:

Background: There is conflicting evidence on the impact of liver disease (CFLD) on life expectancy in CF. Therefore the aim of this systematic review was to evaluate the impact of liver disease (CFLD) on mortality in CF.

Methods: The protocol was published at (https://hrbopenresearch.org/articles/3-44/v3) using PRISPMA-P guidelines and registered in Prospero 2020 (CRD42020182885). Three databases were searched for publications (1938-2020) where the outcome was all-cause mortality (defined as death and transplantation) or CF-specific mortality in participants with CFLD. Studies with and without a comparator group were included. Studies were divided into 2 groups based on the definition of CFLD: Group 1 used 2 categories of liver disease (i) liver disease with portal hypertension (PH) (ii) non-specific abnormalities which did not meet the criteria for PH, Group 2 studies only included participants with PH.

Results: All 14 eligible studies were observational, with a moderate-high risk of bias, Six of the 14 studies directly compared mortality between those with CFLD and those with no liver disease, and 5/6 demonstrated that those with CFLD had at least 3 time the risk of death compared to those with no liver disease. Pulmonary complications were the primary cause of death.

Conclusion: This SR demonstrates that liver disease shortens life expectancy in CF, and that pulmonary complications are the primary cause of death in those with CFLD. There has been no improvement in survival for persons with CFLD despite significant improvements in life expectancy for persons with CF who have no evidence of liver disease.
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http://dx.doi.org/10.1016/j.jcf.2021.07.014DOI Listing
August 2021

Performance Characteristics, Intra- and Inter-Operator Agreement of Tramnsient Elastography in Pediatric Nonalcoholic Fatty Liver Disease.

J Pediatr Gastroenterol Nutr 2021 Jul 27. Epub 2021 Jul 27.

School of Medicine, University College Dublin Ireland Radiography and Diagnostic Imaging, School of Medicine, University College Dublin Children's Health Ireland at Crumlin Dublin 12 Department of Pediatrics, School of Medicine, Royal College of Surgeons in Ireland.

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http://dx.doi.org/10.1097/MPG.0000000000003254DOI Listing
July 2021

The impact of liver disease on mortality in cystic fibrosis - a systematic review protocol.

HRB Open Res 2020 22;3:44. Epub 2020 Dec 22.

School of Medicine, University College Dublin, Dublin, Ireland.

Cystic fibrosis (CF) is a multiorgan disease affecting the lungs pancreas and gastrointestinal tract. Pulmonary complications are the most common manifestation of the disease. Recent advances in the treatment of pulmonary complications have resulted in substantial improvement in life expectancy. Less than 10% of persons with CF (PWCF) develop liver disease (CFLD). There is conflicting evidence about impact of liver disease on mortality in CF, with evidence suggesting that CFLD contributes to increased mortality in CF, while other studies suggest that the impact on mortality is limited. Understanding the contribution of liver disease to mortality in CF is essential if further improvements in life expectancy are to be achieved. To document the impact of liver disease on life expectancy for PWCF. This systematic review will be conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P 2015). PubMed, Medline and Embase will be searched for English language publications (1949-2020). Studies reporting the outcome for CFLD will be included where the definition of CFLD is outlined clearly in a CF population. Studies with and without a comparator will be evaluated. Clinical trials of ursodeoxycholic acid will be excluded as well as organ transplantation outcome studies. We will examine all-cause and specific causes of mortality.We will include transplantation in our estimates of all-cause mortality. The Axis Risk of Bias Tool for Observational Studies will be used to evaluate the quality of studies. We will provide a narrative synthesis of our findings using tabular formats to highlight any impact of liver disease on mortality in CF. It is anticipated that this review will bring clarity to the question of whether CFLD shortens life expectancy in PWCF and stimulate new approaches to the management of CFLD.
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http://dx.doi.org/10.12688/hrbopenres.13065.3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7713883.3PMC
December 2020

NADPH oxidase 4 is protective and not fibrogenic in intestinal inflammation.

Redox Biol 2020 10 7;37:101752. Epub 2020 Oct 7.

Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland; National Children's Research Centre, Children's Health Ireland, Dublin, Ireland. Electronic address:

Dysregulated redox signaling and oxidative injury are associated with inflammatory processes and fibrosis. HO generation by NOX4 has been suggested as a key driver in the development of fibrosis and a small molecule drug is under evaluation in clinical trials for idiopathic pulmonary fibrosis and primary biliary cholangitis. Fibrosis is a common complication in Crohn's disease (CD) leading to stricture formation in 35-40% of patients, who require surgical interventions in the absence of therapeutic options. Here we assess NOX4 expression in CD patients with inflammatory or stricturing disease and examine whether loss of NOX4 is beneficial in acute and fibrotic intestinal disease. NOX4 was upregulated in inflamed mucosal tissue of CD and ulcerative colitis (UC) patients, in CD ileal strictures, and in mice with intestinal inflammation. Nox4 deficiency in mice promoted pathogen colonization and exacerbated tissue injury in acute bacterial and chemical colitis. In contrast, in two chronic injury models aberrant tissue remodeling and fibrosis-related gene expression did not differ substantially between Nox4 mice and wildtype mice, suggesting that Nox4 is dispensable in TGF-β1-driven intestinal fibrogenesis. While animal models do not recapitulate all the hallmarks of CD fibrosis, the tissue-protective role of Nox4 warrants a cautious approach to pharmacological inhibitors.
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http://dx.doi.org/10.1016/j.redox.2020.101752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567035PMC
October 2020

Columnar Lined Esophagus/Gastric Metaplasia Requires Careful Follow-up.

J Pediatr Gastroenterol Nutr 2020 10;71(4):e136

Departments of Gastroenterology and Histopathology, National Children's Research Centre, Children's Hospital Ireland, Crumlin.

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http://dx.doi.org/10.1097/MPG.0000000000002879DOI Listing
October 2020

Repeatability of transient elastography in children.

Pediatr Res 2020 10 1;88(4):587-592. Epub 2020 May 1.

School of Medicine, University College Dublin, Dublin, Ireland.

Background: Poorly performing diagnostic tests can impact patient safety. Clinical investigations must have good precision and diagnostic accuracy before widespread use in clinical practice. Transient elastography (TE) measures liver stiffness, a surrogate marker of liver fibrosis in adults and children. Studies to evaluate its repeatability and reproducibility (precision) in children are limited. Our aim was to determine (i) the normal range of TE measurements and (ii) the repeatability and reproducibility of TE in healthy children.

Methods: TE was performed in 257 healthy children, of whom 235 (91%, mean age 11.7 years, standard deviation (SD) 2.51, 107 were males (45.5%)) had two valid TE measurements performed, at least 24 h apart, by two operators under similar circumstances. High-quality TE images were obtained for each examination.

Results: The normal range of TE was 2.88-6.52 kPa. The mean difference between paired measurements was 0.044 (SD 0.4). The 95% limits of agreement ranged from -0.8 to +0.76 kPa for repeat measurements. There was a difference of >1 kPa between measurements in 61/235 (25.9%) children. The lack of precision was similar across all age groups.

Conclusions: This study demonstrates that TE does not have acceptable precision in healthy children, because random measurement variation results in the lack of agreement between paired measurements.

Impact: The precision and diagnostic accuracy of a new technology must be determined before it is deployed in children in order to ensure that appropriate clinical decisions are made, and healthcare resources are not wasted. TE is widely used to diagnose liver disease in children without adequate evaluation of the precision (repeatability) of TE either in healthy children or children with liver disease. This study demonstrates that TE does not have adequate precision in children. This study was performed in accordance with methods previously published for children. Refinements to the test protocol, such as duration of fasting or probe size, will have to be evaluated for their impact on precision and accuracy before the test is deployed in research studies or clinical practice.
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http://dx.doi.org/10.1038/s41390-020-0916-4DOI Listing
October 2020

Colitis susceptibility in mice with reactive oxygen species deficiency is mediated by mucus barrier and immune defense defects.

Mucosal Immunol 2019 11 25;12(6):1316-1326. Epub 2019 Sep 25.

Conway Institute, University College Dublin, Dublin, Ireland.

Reactive oxygen species (ROS) generated by NADPH oxidases (NOX/DUOX) provide antimicrobial defense, redox signaling, and gut barrier maintenance. Inactivating NOX variants are associated with comorbid intestinal inflammation in chronic granulomatous disease (CGD; NOX2) and pediatric inflammatory bowel disease (IBD; NOX1); however Nox-deficient mice do not reflect human disease susceptibility. Here we assessed if a hypomorphic patient-relevant CGD mutation will increase the risk for intestinal inflammation in mice. Cyba (p22) mutant mice generated low intestinal ROS, while maintaining Nox4 function. The Cyba variant caused profound mucus layer disruption with bacterial penetration into crypts, dysbiosis, and a compromised innate immune response to invading microbes, leading to mortality. Approaches used in treatment-resistant CGD or pediatric IBD such as bone marrow transplantation or oral antibiotic treatment ameliorated or prevented disease in mice. The Cyba mutant mouse phenotype implicates loss of both mucus barrier and efficient innate immune defense in the pathogenesis of intestinal inflammation due to ROS deficiency, supporting a combined-hit model where a single disease variant compromises different cellular functions in interdependent compartments.
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http://dx.doi.org/10.1038/s41385-019-0205-xDOI Listing
November 2019

Gabapentin for the treatment of pain manifestations in children with severe neurological impairment: a single-centre retrospective review.

BMJ Paediatr Open 2019 21;3(1):e000467. Epub 2019 Jul 21.

National Centre for Paediatric Gastroenterology, Hepatology and Nutrition, Children's Health Ireland at Crumlin, Dublin, Ireland.

Pain, irritability and feeding intolerance are common symptoms affecting quality of life in children with severe neurological impairment (SNI). We performed a retrospective study to explore the use of gabapentinoid medications for symptom control in children with SNI. Patients attending the palliative care or gastroenterology department being treated with gabapentin for irritability, vomiting or pain of unknown origin were included. Information was gathered retrospectively from medical documentation. Irritability was reduced in 30 of the 42 patients included. Gabapentin was discontinued in 15 children, 12 of whom then received pregabalin. Three children had a good response to pregabalin, six a minimal improvement and three no improvement. These results support the use of gabapentinoids in this patient cohort.
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http://dx.doi.org/10.1136/bmjpo-2019-000467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6668755PMC
July 2019

Correction to: NADPH Oxidases in Inflammatory Bowel Disease.

Methods Mol Biol 2019 ;1982:C1

Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland.

The title of Chapter 38 was published with a typo error. It should read "NADPH Oxidases in Inflammatory Bowel Disease", whereas the title was mistakenly printed as "NAPDH Oxidases in Inflammatory Bowel Disease" and the book has been updated for this error.
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http://dx.doi.org/10.1007/978-1-4939-9424-3_39DOI Listing
January 2019

NAPDH Oxidases in Inflammatory Bowel Disease.

Methods Mol Biol 2019 ;1982:695-713

Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland.

Inflammatory bowel diseases (IBD), categorized as ulcerative colitis (UC), Crohn's disease (CD), or IBD-undetermined (IBDU), are increasing in incidence. IBD is understood to result from environmental factors interacting with a pre-existing genetic susceptibility. Approximately 1% of all patients with inflammatory bowel disease (IBD) are diagnosed before the age of 6 years, designated as very-early-onset IBD (VEOIBD). This cohort of patients is distinguished from other age groups by differences in disease phenotype and by a higher burden of genetic mutations. Recent studies have linked mutations in NADPH oxidase function to VEOIBD and even pediatric IBD. Loss-of-function NOX2 variants expressed in phagocytes and NOX1/DUOX2 variants expressed in intestinal epithelial cells have been associated with VEOIBD and pediatric and adult IBD in patients. Cell and animal studies suggest a protective role for these reactive oxygen species (ROS)-producing enzymes in intestinal homeostasis-a paradigm that challenges the conventional concept that only increased ROS result in cell and tissue damage. Examining the role of NADPH oxidases in VEOIBD may improve our understanding of the pathophysiology of this disease and will uncover new therapeutic possibilities.
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http://dx.doi.org/10.1007/978-1-4939-9424-3_38DOI Listing
January 2020

The use of stool specimens reveals Helicobacter pylori strain diversity in a cohort of adolescents and their family members in a developed country.

Int J Med Microbiol 2018 Mar 13;308(2):247-255. Epub 2017 Nov 13.

School of Medicine, University College Dublin, Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland. Electronic address:

Helicobacter pylori infection occurs within families but the transmission route is unknown. The use of stool specimens to genotype strains facilitates inclusion of complete families in transmission studies. Therefore, we aimed to use DNA from stools to analyze strain diversity in H. pylori infected families. We genotyped H. pylori strains using specific biprobe qPCR analysis of glmM, recA and hspA. Concentration of H. pylori organisms before DNA isolation enhanced subsequent DNA amplification. We isolated H. pylori DNA from 50 individuals in 13 families. T data for at least 2 of the 3 genes and sequencing of the glmM amplicon were analyzed. Similar strains were commonly found in both mothers and children and in siblings. However, 20/50 (40%) individuals had multiple strains and several individuals harbored strains not found in other family members, suggesting that even in developed countries sources of infection outside of the immediate family may exist. Whether infection occurs multiple times or one transmission event with several strains occurs is not known but future studies should aim to analyze strains from children much closer to infection onset. The presence of multiple stains in infected persons has implications for antibiotic sensitivity testing and treatment strategies.
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http://dx.doi.org/10.1016/j.ijmm.2017.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864523PMC
March 2018

Crohn's Strictures-Moving Away from the Knife.

Front Pediatr 2017 16;5:141. Epub 2017 Jun 16.

School of Medicine, Conway Institute, University College Dublin, Dublin, Ireland.

Crohn's disease (CD) is a lifelong inflammatory bowel disease with a rapidly rising incidence in the pediatric population. A common complication of CD is the development of fibrotic strictures, which may be present at initial diagnosis or develop many years later. Clinical presentation depends on stricture location and degree of obstruction, and strictures frequently contain a mixture of inflammatory and fibrotic tissue. Histological examination of Crohn's strictures shows thickening of the muscular layers and the submucosa, where increased collagen deposition by activated myofibroblasts is concentrated around islands of smooth muscle cells and at the superficial margin of the muscularis propria. No antifibrotic therapies for Crohn's strictures exist. Profibrotic transforming growth factor-β (TGFβ)/bone morphogenetic protein signaling stimulates myofibroblast differentiation and extracellular matrix deposition. Understanding and targeting TGFβ1 downstream signaling is the main focus of current research, raising the possibility of specific antifibrotic therapy in CD becoming available in the future.
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http://dx.doi.org/10.3389/fped.2017.00141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5472668PMC
June 2017

Erratum to: Assays to Study the Interaction of Campylobacter jejuni with the Mucosal Surface.

Methods Mol Biol 2017 ;1512:E1

Conway Institute, School of Medicine and Medical Science, University College Dublin, Dublin 12, Ireland.

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http://dx.doi.org/10.1007/978-1-4939-6536-6_22DOI Listing
January 2017

Relaxation of DNA supercoiling leads to increased invasion of epithelial cells and protein secretion by Campylobacter jejuni.

Mol Microbiol 2017 04 6;104(1):92-104. Epub 2017 Feb 6.

School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.

Invasion of intestinal epithelial cells by Campylobacter jejuni is a critical step during infection of the intestine by this important human pathogen. In this study we investigated the role played by DNA supercoiling in the regulation of invasion of epithelial cells and the mechanism by which this could be mediated. A significant correlation between more relaxed DNA supercoiling and an increased ability of C. jejuni strains to penetrate human epithelial cells was demonstrated. Directly inducing relaxation of DNA supercoiling in C. jejuni was shown to significantly increase invasion of epithelial cells. Mutants in the fibronectin binding proteins CadF and FlpA still displayed an increased invasion after treatment with novobiocin suggesting these proteins were not essential for the observed phenotype. However, a large increase in protein secretion from multiple C. jejuni strains upon relaxation of DNA supercoiling was demonstrated. This increase in protein secretion was not mediated by outer membrane vesicles and appeared to be dependent on an intact flagellar structure. This study identifies relaxation of DNA supercoiling as playing a key role in enhancing C. jejuni pathogenesis during infection of the human intestine and identifies proteins present in a specific invasion associated secretome induced by relaxation of DNA supercoiling.
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http://dx.doi.org/10.1111/mmi.13614DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6592826PMC
April 2017

Assays to Study the Interaction of Campylobacter jejuni with the Mucosal Surface.

Methods Mol Biol 2017 ;1512:129-147

Conway Institute, School of Medicine and Medical Science, University College Dublin, Dublin 12, Ireland.

Mucosal colonization and overcoming the mucosal barrier are essential steps in the establishment of infection by Campylobacter jejuni. The interaction between C. jejuni and host cells, including binding and invasion, is thought to be the key virulence factor important for pathogenesis of C. jejuni infections in animals or humans. The intestinal mucosal barrier is composed of a polarized epithelium covered by a thick adherent mucus gel layer. There is a requirement for cell culture assays of infection to accurately represent the in vivo mucosal surface. In this chapter, we describe the use of a number of cell culture models and the use of polarized in vitro organ culture to examine the interaction of C. jejuni with mucosal surfaces.
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http://dx.doi.org/10.1007/978-1-4939-6536-6_12DOI Listing
January 2018

Methods to Assess the Direct Interaction of C. jejuni with Mucins.

Methods Mol Biol 2017 ;1512:107-115

Conway Institute, School of Medicineand Medical Science, University College Dublin, Dublin, Ireland.

Studies of the interaction of bacteria with mucus-secreting cells can be complemented at a more mechanistic level by exploring the interaction of bacteria with purified mucins. Here we describe a far Western blotting approach to show how C. jejuni proteins separated by SDS PAGE and transferred to a membrane or slot blotted directly onto a membrane can be probed using biotinylated mucin. In addition we describe the use of novel mucin microarrays to assess bacterial interactions with mucins in a high-throughput manner.
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http://dx.doi.org/10.1007/978-1-4939-6536-6_10DOI Listing
January 2018

DNA Supercoiling Regulates the Motility of Campylobacter jejuni and Is Altered by Growth in the Presence of Chicken Mucus.

mBio 2016 09 13;7(5). Epub 2016 Sep 13.

School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland National Children's Research Centre, Our Lady's Hospital for Sick Children, Crumlin, Dublin, Ireland

Unlabelled: Campylobacter jejuni is the leading cause of bacterial gastroenteritis in humans, but relatively little is known about the global regulation of virulence factors during infection of chickens or humans. This study identified DNA supercoiling as playing a key role in regulating motility and flagellar protein production and found that this supercoiling-controlled regulon is induced by growth in chicken mucus. A direct correlation was observed between motility and resting DNA supercoiling levels in different strains of C. jejuni, and relaxation of DNA supercoiling resulted in decreased motility. Transcriptional analysis and Western immunoblotting revealed that a reduction in motility and DNA supercoiling affected the two-component regulatory system FlgRS and was associated with reduced FlgR expression, increased FlgS expression, and aberrant expression of flagellin subunits. Electron microscopy revealed that the flagellar structure remained intact. Growth in the presence of porcine mucin resulted in increased negative supercoiling, increased motility, increased FlgR expression, and reduced FlgS expression. Finally, this supercoiling-dependent regulon was shown to be induced by growth in chicken mucus, and the level of activation was dependent on the source of the mucus from within the chicken intestinal tract. In conclusion, this study reports for the first time the key role played by DNA supercoiling in regulating motility in C. jejuni and indicates that the induction of this supercoiling-induced regulon in response to mucus from different sources could play a critical role in regulating motility in vivo

Importance: Although Campylobacter jejuni is the leading cause of bacterial gastroenteritis, very little is understood about how this pathogen controls the expression of genes involved in causing disease. This study for the first time identifies DNA supercoiling as a key regulator of motility in C. jejuni, which is essential for both pathogenesis and colonization. Altering the level of DNA supercoiling results in changes in motility levels, as well as changes in the expression of genes involved in flagellar gene regulation. Furthermore, spontaneous clones of the organism with different motility profiles have altered DNA supercoiling levels. Finally, mucus was identified as a key stimulator of changes in DNA supercoiling, and it was shown that mucus from different sites in the chicken intestine induced different levels of DNA supercoiling. In conclusion, this study implicates DNA supercoiling as a key regulator of motility in C. jejuni in vivo during colonization of the mucus layer.
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http://dx.doi.org/10.1128/mBio.01227-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5021803PMC
September 2016

NADPH oxidase-derived H2O2 subverts pathogen signaling by oxidative phosphotyrosine conversion to PB-DOPA.

Proc Natl Acad Sci U S A 2016 09 25;113(37):10406-11. Epub 2016 Aug 25.

National Children's Research Center, Our Lady's Children's Hospital Crumlin, Dublin 12, Ireland; Conway Institute, School of Medicine, University College Dublin, Dublin 4, Ireland;

Strengthening the host immune system to fully exploit its potential as antimicrobial defense is vital in countering antibiotic resistance. Chemical compounds released during bidirectional host-pathogen cross-talk, which follows a sensing-response paradigm, can serve as protective mediators. A potent, diffusible messenger is hydrogen peroxide (H2O2), but its consequences on extracellular pathogens are unknown. Here we show that H2O2, released by the host on pathogen contact, subverts the tyrosine signaling network of a number of bacteria accustomed to low-oxygen environments. This defense mechanism uses heme-containing bacterial enzymes with peroxidase-like activity to facilitate phosphotyrosine (p-Tyr) oxidation. An intrabacterial reaction converts p-Tyr to protein-bound dopa (PB-DOPA) via a tyrosinyl radical intermediate, thereby altering antioxidant defense and inactivating enzymes involved in polysaccharide biosynthesis and metabolism. Disruption of bacterial signaling by DOPA modification reveals an infection containment strategy that weakens bacterial fitness and could be a blueprint for antivirulence approaches.
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http://dx.doi.org/10.1073/pnas.1605443113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027431PMC
September 2016

Defensive Mutualism Rescues NADPH Oxidase Inactivation in Gut Infection.

Cell Host Microbe 2016 May;19(5):651-63

Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland; National Children's Research Center, Our Lady's Children's Hospital Crumlin, Dublin 12, Ireland. Electronic address:

NOX/DUOX family of NADPH oxidases are expressed in diverse tissues and are the primary enzymes for the generation of reactive oxygen species (ROS). The intestinal epithelium expresses NOX1, NOX4, and DUOX2, whose functions are not well understood. To address this, we generated mice with complete or epithelium-restricted deficiency in the obligatory NOX dimerization partner Cyba (p22(phox)). We discovered that NOX1 regulates DUOX2 expression in the intestinal epithelium, which magnified the epithelial ROS-deficiency. Unexpectedly, epithelial deficiency of Cyba resulted in protection from C. rodentium and L. monocytogenes infection. Microbiota analysis linked epithelial Cyba deficiency to an enrichment of H2O2-producing bacterial strains in the gut. In particular, elevated levels of lactobacilli physically displaced and attenuated C. rodentium virulence by H2O2-mediated suppression of the virulence-associated LEE pathogenicity island. This transmissible compensatory adaptation relied on environmental factors, an important consideration for prevention and therapy of enteric disease.
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http://dx.doi.org/10.1016/j.chom.2016.04.007DOI Listing
May 2016

Defects in NADPH Oxidase Genes and in Very Early Onset Inflammatory Bowel Disease.

Cell Mol Gastroenterol Hepatol 2015 Sep;1(5):489-502

Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland ; National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.

Background & Aims: Defects in intestinal innate defense systems predispose patients to inflammatory bowel disease (IBD). Reactive oxygen species (ROS) generated by nicotinamide-adenine dinucleotide phosphate (NADPH) oxidases in the mucosal barrier maintain gut homeostasis and defend against pathogenic attack. We hypothesized that molecular genetic defects in intestinal NADPH oxidases might be present in children with IBD.

Methods: After targeted exome sequencing of epithelial NADPH oxidases and on 209 children with very early onset inflammatory bowel disease (VEOIBD), the identified mutations were validated using Sanger Sequencing. A structural analysis of and variants was performed by homology in silico modeling. The functional characterization included ROS generation in model cell lines and in in vivo transduced murine crypts, protein expression, intracellular localization, and cell-based infection studies with the enteric pathogens and enteropathogenic .

Results: We identified missense mutations in (c.988G>A, p.Pro330Ser; c.967G>A, p.Asp360Asn) and (c.4474G>A, p.Arg1211Cys; c.3631C>T, p.Arg1492Cys) in 5 of 209 VEOIBD patients. The p.Asp360Asn variant was replicated in a male Ashkenazi Jewish ulcerative colitis cohort. All and variants showed reduced ROS production compared with wild-type enzymes. Despite appropriate cellular localization and comparable pathogen-stimulated translocation of altered oxidases, cells harboring or variants had defective host resistance to infection with .

Conclusions: This study identifies the first inactivating missense variants in and associated with VEOIBD. Defective ROS production from intestinal epithelial cells constitutes a risk factor for developing VEOIBD.
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http://dx.doi.org/10.1016/j.jcmgh.2015.06.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539615PMC
September 2015

Clinical and genetic characterisation of infantile liver failure syndrome type 1, due to recessive mutations in LARS.

J Inherit Metab Dis 2015 Nov 28;38(6):1085-92. Epub 2015 Apr 28.

UCD Academic Centre on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland.

Background: Recessive LARS mutations were recently reported to cause a novel syndrome, infantile liver failure syndrome type 1 (ILFS1), in six Irish Travellers. We have since identified four additional patients, including one of Ashkenazi origin, representing the largest ILFS1 cohort to date. Our study aims to define the ILFS1 clinical phenotype to help guide diagnosis and patient management.

Methods: We clinically evaluated and reviewed the medical records of ten ILFS1 patients. Clinical features, histopathology and natural histories were compared and patient management strategies reviewed.

Results: Early failure to thrive, recurrent liver dysfunction, anemia, hypoalbuminemia and seizures were present in all patients. Most patients (90 %) had developmental delay. Encephalopathic episodes triggered by febrile illness have occurred in 80 % and were fatal in two children. Two patients are currently >28 years old and clinically well. Leucine supplementation had no appreciable impact on patient well-being. However, we suggest that the traditional management of reducing/stopping protein intake in patients with metabolic hepatopathies may not be appropriate for ILFS1. We currently recommend ensuring sufficient natural protein intake when unwell.

Conclusions: We report the first non-Irish ILFS1 patient, suggesting ILFS1 may be more extensive than anticipated. Low birth weight, early failure to thrive, anemia and hypoalbuminemia are amongst the first presenting features, with liver dysfunction before age 1. Episodic hepatic dysfunction is typically triggered by febrile illness, and becomes less severe with increasing age. While difficult to anticipate, two patients are currently >28 years old, suggesting that survival beyond childhood may be associated with a favourable long-term prognosis.
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http://dx.doi.org/10.1007/s10545-015-9849-1DOI Listing
November 2015

Chronic infections of the small intestine.

Curr Opin Gastroenterol 2015 Mar;31(2):104-10

aNational Centre for Paediatric Gastroenterology, Our Lady's Children's Hospital bNational Children's Research Centre, Crumlin, Dublin cUCD School of Medicine and Medical Science dConway Institute, University College Dublin, Belfield, Dublin, Ireland.

Purpose Of Review: Chronic infections of the small intestine cause significant morbidity and mortality globally. This review focuses on the recent advances in the field of our understanding of selected intestinal infections.

Recent Findings: Primary and secondary immunodeficiency increase the susceptibility to many chronic intestinal infections. Endoscopy and intestinal biopsies are central to establishing a diagnosis of these conditions. Tuberculosis (TB) remains a major global health challenge. Emerging therapeutic agents to counteract multidrug-resistant strains have shown clinical efficacy, but concerns regarding mortality remain. PCR-based diagnostic TB tests have the potential to reduce diagnostic delays, but remain to be validated for intestinal infections. Adjunctive diagnostic imaging modalities can differentiate infections from Crohn's disease with increasing accuracy. Whipple's disease remains rare, but there have been substantial advances in our understanding of the causative organism Tropheryma whipplei. Extended treatment with broad-spectrum antibiotics is effective in most cases. The narrow therapeutic window and limited armamentarium for treating invasive filamentous fungal infections contribute to their significant morbidity and high rates of mortality.

Summary: The speed and accuracy of diagnosing chronic intestinal infections have improved with recent imaging and laboratory methodologies. Significant research opportunities remain for clinicians and scientists to improve the diagnostic accuracy and clinical outcomes of chronic intestinal infections.
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http://dx.doi.org/10.1097/MOG.0000000000000153DOI Listing
March 2015

Outcomes of children after esophagogastroduodenoscopy for chronic abdominal pain.

Authors:
Billy Bourke

Clin Gastroenterol Hepatol 2015 Feb 12;13(2):409. Epub 2014 Aug 12.

National Referral Center for Paediatric Gastroenterology, Our Ladys Children Hospital Crumlin/National Children's Research Center, University College, Dublin, Ireland.

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http://dx.doi.org/10.1016/j.cgh.2014.08.007DOI Listing
February 2015

Outcome in patients with cystic fibrosis liver disease.

J Cyst Fibros 2015 Jan 7;14(1):120-6. Epub 2014 Jun 7.

St Vincent's University Hospital Elm Park, Dublin 4, Ireland; Our Lady's Children's Hospital Crumlin, Dublin 12, Ireland.

Background: Liver disease is an important complication in CF.

Aims: To determine if CFLD is a risk factor for mortality in CF, and which baseline characteristics predict all-cause mortality.

Methods: Irish children with CFLD, and their age and gender matched controls were enrolled at baseline and reviewed after 10years to determine which characteristics predict mortality.

Results: 72/84 (85.71%) participants were followed, (mean age Cases 21.71yrs SD 6.5, CF controls 23.62 SD 5.6, 22 (61%) males), with no difference in duration of follow-up. Nineteen participants (26.4%) died, 38.9% (14/36) with CFLD and 13.89% (5/36) CF controls (Odds Ratio (OR) 3.94 95% CI:1.23-12.56 p=0.005). In logistic regression, liver disease (OR 4.28 95% CI 1.07-17.16) female gender (OR 12.25 95% CI 2.37-63.24), reduced pulmonary function, (OR 5.11 95% CI 1.09-23.81) were each independent risk factors for mortality in CF.

Conclusions: Liver disease is an independent risk factor for mortality in CF.
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http://dx.doi.org/10.1016/j.jcf.2014.05.013DOI Listing
January 2015

Interaction of microbes with mucus and mucins: recent developments.

Gut Microbes 2014 Jan-Feb;5(1):48-52. Epub 2013 Oct 2.

School of Medicine and Medical Science; University College Dublin; Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Science; University College Dublin; Dublin, Ireland.

Due to the recent rapid expansion in our understanding of the composition of the gut microflora and the consequences of altering that composition the question of how bacteria colonise mucus layers and interact with components of mucus, such as mucin, is now receiving widespread attention. Using a combination of mucus secreting cells, and a novel mucin microarray platform containing purified native mucins from different sources we recently demonstrated that two gastrointestinal pathogens, Helicobacter pylori and Campylobacter jejuni, colonise mucus by different mechanisms. This result emphasizes the potential for even closely related bacteria to interact with mucus in divergent ways to establish successful infection. Expanding the use of the mucin arrays described in the study to other microorganisms, both pathogenic and commensal, should lead to the discovery of biologically important motifs in bacterial-host interactions and complement the use of novel in vitro cell models, such as mucus secreting cell lines.
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http://dx.doi.org/10.4161/gmic.26680DOI Listing
January 2015

Cj1411c encodes for a cytochrome P450 involved in Campylobacter jejuni 81-176 pathogenicity.

PLoS One 2013 26;8(9):e75534. Epub 2013 Sep 26.

National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.

Cytochrome P450s are b-heme-containing enzymes that are able to introduce oxygen atoms into a wide variety of organic substrates. They are extremely widespread in nature having diverse functions at both biochemical and physiological level. The genome of C. jejuni 81-176 encodes a single cytochrome P450 (Cj1411c) that has no close homologues. Cj1411c is unusual in its genomic location within a cluster involved in the biosynthesis of outer surface structures. Here we show that E. coli expressed and affinity-purified C. jejuni cytochrome P450 is lipophilic, containing one equivalent Cys-ligated heme. Immunoblotting confirmed the association of cytochrome P450 with membrane fractions. A Cj1411c deletion mutant had significantly reduced ability to infect human cells and was less able to survive following exposure to human serum when compared to the wild type strain. Phenotypically following staining with Alcian blue, we show that a Cj1411c deletion mutant produces significantly less capsular polysaccharide. This study describes the first known membrane-bound bacterial cytochrome P450 and its involvement in Campylobacter virulence.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0075534PLOS
July 2014

Divergent mechanisms of interaction of Helicobacter pylori and Campylobacter jejuni with mucus and mucins.

Infect Immun 2013 Aug 28;81(8):2838-50. Epub 2013 May 28.

School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.

Helicobacter pylori and Campylobacter jejuni colonize the stomach and intestinal mucus, respectively. Using a combination of mucus-secreting cells, purified mucins, and a novel mucin microarray platform, we examined the interactions of these two organisms with mucus and mucins. H. pylori and C. jejuni bound to distinctly different mucins. C. jejuni displayed a striking tropism for chicken gastrointestinal mucins compared to mucins from other animals and preferentially bound mucins from specific avian intestinal sites (in order of descending preference: the large intestine, proximal small intestine, and cecum). H. pylori bound to a number of animal mucins, including porcine stomach mucin, but with less avidity than that of C. jejuni for chicken mucin. The strengths of interaction of various wild-type strains of H. pylori with different animal mucins were comparable, even though they did not all express the same adhesins. The production of mucus by HT29-MTX-E12 cells promoted higher levels of infection by C. jejuni and H. pylori than those for the non-mucus-producing parental cell lines. Both C. jejuni and H. pylori bound to HT29-MTX-E12 mucus, and while both organisms bound to glycosylated epitopes in the glycolipid fraction of the mucus, only C. jejuni bound to purified mucin. This study highlights the role of mucus in promoting bacterial infection and emphasizes the potential for even closely related bacteria to interact with mucus in different ways to establish successful infections.
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http://dx.doi.org/10.1128/IAI.00415-13DOI Listing
August 2013

How to use Helicobacter pylori testing in paediatric practice.

Arch Dis Child Educ Pract Ed 2013 Feb 23;98(1):18-25. Epub 2012 Oct 23.

National Centre for Paediatric Gastroenterology, Hepatology and Nutrition, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.

The current reference standard for investigating H. pylori associated disease in children remains upper intestinal endoscopy and biopsies for histology and culture or RUT. Non-invasive tests should be used to confirm H. pylori eradication following treatment. Currently there is insufficient evidence to recommend them over invasive tests in symptomatic children, because they cannot be used reliably in children to diagnose or distinguish H. pylori-associated diseases from conditions that are not H. pylori related. Recent evidence-based guidelines recommend treatment in children with confirmed H. pylori–related diseases. However, with further knowledge of the measurable health risks for H. pylori–infected children, or with the availability of vaccination or future treatment options, the risk-benefit relationship and recommendations regarding non-invasive testing may change.
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http://dx.doi.org/10.1136/archdischild-2012-301642DOI Listing
February 2013

Defense and adaptation: the complex inter-relationship between Campylobacter jejuni and mucus.

Front Cell Infect Microbiol 2012 20;2:15. Epub 2012 Feb 20.

Department of Biological Sciences, University of Alberta Edmonton, AB, Canada.

Mucus colonization is an essential early step toward establishing successful infection and disease by mucosal pathogens. There is an emerging literature implicating specific mucin sub-types and mucin modifications in protecting the host from Campylobacter jejuni infection. However, mucosal pathogens have evolved sophisticated mechanisms to breach the mucus layer and C. jejuni in particular appears to harbor specific adaptations to better colonize intestinal mucus. For example, components of mucus are chemotactic for C. jejuni and the rheological properties of mucus promote motility of the organism. Furthermore, recent studies demonstrate that mucins modulate the pathogenicity of C. jejuni in a species-specific manner and likely help determine whether these bacteria become pathogenic (as in humans), or adopt a commensal mode of existence (as in chickens and other animals). This review focuses on recent advances in understanding the complex interplay between C. jejuni and components of the mucus layer.
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http://dx.doi.org/10.3389/fcimb.2012.00015DOI Listing
December 2013
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