Nonsense mutation in the novel PERCC1 gene as a genetic cause of congenital diarrhea and enteropathy.

Congenital diarrheas and enteropathies (CODEs) constitute a heterogeneous group of individually rare disorders manifesting with infantile-onset chronic diarrhea. Genomic deletions in chromosome 16, encompassing a sequence termed the 'intestine-critical region (ICR)', were recently identified as the cause of an autosomal recessive congenital enteropathy. The regulatory sequence within the ICR is flanked by an unannotated open reading frame termed PERCC1, which plays a role in enteroendocrine cell (EEC) function. We investigated two unrelated children with idiopathic congenital diarrhea requiring home parenteral nutrition attending the Irish Intestinal Failure Program. Currently 12 and 19-years old, these Irish male patients presented with watery diarrhea and hypernatremic dehydration in infancy. Probands were phenotyped by comprehensive clinical investigations, including endoscopic biopsies and serum gastrin level measurements. Following negative exome sequencing, PCR and Sanger sequencing of the entire coding region and intron boundaries of PERCC1 were performed for each proband and their parents. In both patients, serum gastrin levels were low and failed to increase following a meal challenge. While no deletions involving the ICR were detected, targeted sequencing of the PERCC1 gene revealed a shared homozygous c.390C > G stop gain variant. We report clinical and molecular findings in two unrelated patients harboring a shared homozygous variant in PERCC1, comprising the first description of a point mutation in this gene in association with CODE. That both parenteral nutrition dependent children with unexplained diarrhea at our institution harbored a PERCC1 mutation underscores the importance of its inclusion in exome sequencing interpretation.

Mucosal Atrophy Predicts Poorer Outcomes in Pediatric Ulcerative Colitis-A National Inception Cohort Study.

BACKGROUND: Outcomes in pediatric ulcerative colitis (UC) are heterogeneous and predictors of disease course eagerly sought. Mucosal atrophy (MA) is characterized by histological abnormalities of colonic intestinal glands. OBJECTIVE: To determine the prevalence of MA in a national inception cohort of pediatric UC and its impact on outcomes. METHODS: Irish children < 16 years old with UC are diagnosed at a single referral center. At diagnosis, patients underwent phenotyping by Paris classification and activity assessment by Pediatric Ulcerative Colitis Activity Index. Biopsies from all colonic segments were evaluated for MA. Patients were followed prospectively. The primary outcome was corticosteroid-free remission at 1 year. Secondary outcomes included relapse, treatment escalation, and colectomy by 2 years. RESULTS: Of 251 pediatric patients with UC (mean age 11.8 years, 55% male), 38 (15%) had MA on diagnostic biopsy. Baseline characteristics were similar between groups with/without MA and there was no difference in steroid-free remission or rates of moderate-severe UC at 1 year. Patients with MA had higher use of steroids (29% vs 15%, P = 0.04) and immunomodulators (40% vs 21%, P = 0.04) at 6 months, higher biologic use at 1 year (34% vs 16%, P = 0.03), earlier first relapse (mean ± SD 29.4 ± 26.1 vs 46.7 ± 43.4 weeks after diagnosis, P = 0.02), and higher colectomy rates by 2 years (21% vs 8%, P = 0.01). CONCLUSIONS: Children with MA at diagnosis had higher colectomy rates despite earlier treatment escalation and similar baseline severity scores. We identify MA as a promising new prognostic marker in children with newly diagnosed UC.

Repeatability of transient elastography in children.

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.

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

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.

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

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.

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

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. Tm 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.

Chronic infections of the small intestine.

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.

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

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.

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

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.

How to use Helicobacter pylori testing in paediatric practice.

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. pylori­related diseases. However, with further knowledge of the measurable health risks for H. pylori­infected children, or with the availability of vaccination or future treatment options, the risk-benefit relationship and recommendations regarding non-invasive testing may change.

Outcomes of Tofacitinib Use in an Irish Pediatric Cohort.

Background: Pediatric ulcerative colitis (UC) is typically more extensive and severe at diagnosis compared with adult disease. Tofacitinib, a Janus kinase inhibitor, has been used since 2018 to induce and maintain remission in UC. There are limited pediatric data regarding its use, either as a monotherapy or in combination with other treatments. Objectives: To determine the real-world experience and outcomes of tofacitinib therapy in the Irish national cohort with pediatric UC. Methods: A retrospective study of tofacitinib outcomes was undertaken at Ireland's single national center for pediatric inflammatory bowel disease. All patients commenced on tofacitinib since its availability in 2019 were included. Baseline and follow-up clinical characteristics, phenotype, Pediatric Ulcerative Colitis Activity Index (PUCAI) scores, and treatments before and after tofacitinib commenced were recorded. The primary outcome was remission by 8 weeks, with other clinical outcomes being recorded to maximal available follow-up. Results: Between November 1, 2019 and June 30, 2022, 15 children (M:F 1:2) were prescribed tofacitinib, 5 as monotherapy. Thirteen had baseline pancolitis at diagnosis and all patients had prior infliximab exposure. The mean time from diagnosis to starting tofacitinib was 381 days (±SD 265). Dual therapy included 5 with infliximab, 4 with vedolizumab, and 1 with adalimumab. The average length of treatment on tofacitinib was 232 days (±SD 170) with 2 patients transitioning to adult services while in remission on tofacitinib therapy. The mean PUCAI score was 48.7 (±SD 14.1) pre-tofacitinib, 16.7 (±SD 15.6) at week 8, and 22.5 (±SD 29.6) by week 16, with a significant reduction in PUCAI by week 16 (P = 0.0004). Eight patients (3 monotherapy) achieved clinical remission, with 4 of the 5 dual therapy patients on infliximab. There were no significant outcome differences between those on mono- or dual therapy. Three patients with combined vedolizumab therapy did not achieve remission, 2 of whom required colectomy by week 24. There were no malignancies, 1 patient developed shingles and another developed herpangina post-tofacitinib. Failure to achieve clinical remission by week 16 was seen in all children who progressed to colectomy (n = 4). Conclusion: Combining tofacitinib with other biologics is effective in select children with refractory UC. Early responders were more likely to achieve a sustained response at week 16. Failure to achieve remission by week 16 of tofacitinib therapy was strongly associated with progression to colectomy.

The natural history of cystic fibrosis liver disease a prospective cohort study.

BACKGROUND: Our understanding of the natural history of cystic fibrosis liver disease (CFLD) is limited, leading to uncertainty for patients their families and clinicians when liver abnormalities are identified. AIM: to determine the incidence of CFLD, identify risk factors and document the natural history of liver abnormalities in cystic fibrosis (CF). METHODS: The Irish longitudinal study of CFLD (ILSCFLD) prospectively enrolled 95% of children with CF in 2007. Their liver disease status was classified as (i) advanced liver disease with portal hypertension (CFLD). (ii) nonspecific cystic fibrosis liver disease (NSCFLD) (iii) no liver disease (NoLD) RESULTS: 480/522 (91.9%) children were followed for a median 8.53 years IQR 1.28, of whom 35 (7.29%) had CFLD, 110 (22.9%) NSCFLD and 335 (69.79%) had NoLD. At follow-up 28/445 (6.29%) participants without CFLD at baseline, progressed to CFLD (Incidence 7.51/1000 person years (Pyrs) (95%CI 4.99-10.86). Of these 25/28(89.28%) were <10 years. No participant >10 years of age without clinical or radiological evidence of liver disease at baseline progressed to CFLD. During follow-up 18/35(51.43%) participants with CFLD died or received a transplant, MTx rate 7.75/100 Pyrs (95%CI 4.59-12.25) compared to NSCFLD 2.33/100 Pyrs (95%CI 1.44-3.56) and NoLD 1.13/100 Pyrs (95%CI 0.77-1.59). CFLD was an independent risk factor for mortality in CF. Children with CFLD also had a shorter life expectancy. CONCLUSION: The incidence of CFLD was highest in children under10 years. Children over10 years, with normal hepatic function did not develop CFLD. Research to identify the cause and improve outcome should focus on young children.

Identification of a mutation in LARS as a novel cause of infantile hepatopathy.

Infantile hepatopathies are life-threatening liver disorders that manifest in the first few months of life. We report on a consanguineous Irish Traveller family that includes six individuals presenting with acute liver failure in the first few months of life. Additional symptoms include anaemia, renal tubulopathy, developmental delay, seizures, failure to thrive and deterioration of liver function with minor illness. The multisystem manifestations suggested a possible mitochondrial basis to the disorder. However, known causes of childhood liver failure and mitochondrial disease were excluded in this family by biochemical, metabolic and genetic analyses. We aimed to identify the underlying risk gene using homozygosity mapping and whole exome sequencing. SNP homozygosity mapping identified a candidate locus at 5q31.3-q33.1. Whole exome sequencing identified 1 novel homozygous missense mutation within the 5q31.3-q33.1 candidate region that segregated with the hepatopathy. The candidate mutation is located in the LARS gene which encodes a cytoplasmic leucyl-tRNA synthetase enzyme responsible for exclusively attaching leucine to its cognate tRNA during protein translation. Knock-down of LARS in HEK293 cells did not impact on mitochondrial function even when the cells were put under physiological stress. The molecular studies confirm the findings of the patients' biochemical and genetic analyses which show that the hepatopathy is not a mitochondrial-based dysfunction problem, despite clinical appearances. This study highlights the clinical utility of homozygosity mapping and exome sequencing in diagnosing recessive liver disorders. It reports mutation of a cytoplasmic aminoacyl-tRNA synthetase enzyme as a possible novel cause of infantile hepatopathy and underscores the need to consider mutations in LARS in patients with liver disease and multisystem presentations.

Clinical presentation of and outcome for solitary rectal ulcer syndrome in children.

BACKGROUND AND AIMS: Solitary rectal ulcer syndrome (SRUS) is an uncommon but troublesome and easily misdiagnosed condition of childhood. We have reviewed the presentation and outcome following conservative management of a group of children with SRUS attending a single national paediatric gastrointesinal referral unit. METHODS: Eight children were identified with histology-proven SRUS. Chart review was conducted for relevant history and examination at diagnosis. Patients were contacted to assess success of treatment at the time of follow-up. RESULTS: Symptoms at presentation included repeated prolonged and ineffectual straining at stool, passage of blood/mucous per rectum, diarrhoea, and constipation. Most children were referred with suspected constipation, diarrhoea, or inflammatory bowel disease. On the basis of retrospective chart review, 7 of 8 children responded well to conservative management (behavioural modification programme involving reduction of time spent straining at defecation). The child failing treatment could not comply with advice because of comorbid autism. Six of the initial responders were available for follow-up. Four were asymptomatic. Two had relapsed and were not compliant with the management programme. DISCUSSION/CONCLUSIONS: SRUS can masquerade as more common childhood intestinal conditions such as inflammatory bowel disease or constipation. A biopsy is required for diagnosis, because ulceration may not be apparent at the time of endoscopy. Most patients with SRUS in childhood have a satisfactory outcome using a simple behavioural modification approach. Ongoing follow-up to reinforce behavioural modification is important and may avoid long-term, treatment-resistant disease into adulthood.

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

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.

Outcome in cystic fibrosis liver disease.

OBJECTIVES: Evidence suggests that cystic fibrosis liver disease (CFLD) does not affect mortality or morbidity in patients with cystic fibrosis (CF). The importance of gender and age in outcome in CF makes selection of an appropriate comparison group central to the interpretation of any differences in mortality and morbidity in patients with CFLD. METHODS: This is a 7-year follow-up of 42 children with CFLD and their age- and sex-matched controls. Participants were reviewed clinically, biochemically, and radiologically at follow-up. RESULTS: Overall, 85% (72 of 84) of the original cohort were included, 36 CFLD participants and 36 CF controls. There was no significant difference in the number of deaths/transplants between groups (7 of 36 (19.4%) CFLD participants, 3 of 36 (8.3%) CF controls). There was a tendency for participants with CFLD to die younger than their respective CF controls. There was no difference in height, weight, body mass index, or pulmonary function between the groups. Nutritional parameters (sum skinfold thickness 31.6 vs. 42.3, P=0.03; mean upper arm fat area 15.08 vs. 10.59, P=0.001; Shwachman score 43.7 vs. 32.1, P=0.001) were worse among CFLD participants than among CF controls. Cystic fibrosis-related diabetes was more common in CFLD participants (11 of 27 (40.7%) vs. 5 of 33 (15.2%), P=0.02). Eight children (22.2%) with evidence of CFLD at baseline had no clinical evidence of liver disease as adults. CONCLUSIONS: Patients with CFLD have a more severe CF phenotype than do CF patients without liver disease. However, a subgroup of children with CFLD will not manifest clinically significant liver disease as adults.