Safety and efficacy of linaclotide in children aged 7-17 years with irritable bowel syndrome with constipation.

OBJECTIVES: Linaclotide, a guanylate cyclase-C agonist, was recently approved in the United States for the treatment of children 6-17 years old with functional constipation. This study evaluated the safety and efficacy of various linaclotide doses in children 7-17 years old with irritable bowel syndrome with constipation (IBS-C). METHODS: In this 4-week, randomized, double-blind, placebo-controlled, parallel-group, Phase 2 study, children with IBS-C were randomized to once-daily placebo or linaclotide (Dose A: 18 or 36 µg, B: 36 or 72 µg, and C: 72 µg or 145 µg, or 290 µg); those aged 7-11 years in a 1:1:1:1 allocation based on weight (18 to <35 kg:18 µg, 36 µg, or 72 µg; or ≥35 kg: 36 µg, 72 µg, or 145 µg), and those aged 12-17 years in a 1:1:1:1:1 allocation (the higher option of Doses A-C or 290 µg). The primary efficacy endpoint was a change from baseline in 4-week overall spontaneous bowel movement (SBM) frequency rate over the treatment period. Adverse events and clinical laboratory measures were also assessed. RESULTS: Efficacy, safety, and tolerability were assessed in 101 patients. In the intent-to-treat population, numerical improvement was observed in overall SBM frequency rate with increasing linaclotide doses (A: 1.62, B: 1.52, and C: 2.30, 290 µg: 3.26) compared with placebo. The most reported treatment-emergent adverse events were diarrhea and pain, with most cases being mild and none being severe. CONCLUSIONS: Linaclotide was tolerated well in this pediatric population, showing numerical improvement in SBM frequency compared with placebo.

Safety and efficacy of linaclotide in children aged 2-5 years with functional constipation: Phase 2, randomized study.

OBJECTIVES: Linaclotide, a guanylate cyclase-C agonist, was recently approved in the United States for the treatment of children 6-17 years of age with functional constipation (FC). This study evaluated the dose-response, safety, and efficacy of 4 weeks of linaclotide compared with placebo in children 2-5 years of age with FC. METHODS: In this phase 2, randomized, double-blind, placebo-controlled, multidose study, 35 children with FC (based on Rome III criteria) were randomized 3:1 to receive linaclotide (18, 36, or 72 µg, for groups 1, 2, and 3, respectively) and 5:1 to receive linaclotide 9, 18, 36, or 72 µg (group 4), or matching placebo. Key endpoints were the changes from baseline in overall spontaneous bowel movement (SBM) frequency (SBMs/week), stool consistency, and straining, as well as the proportion of days with fecal incontinence during the study intervention period. Adverse events (AEs) were recorded. RESULTS: Of the randomized patients, 34 (97.1%) completed the treatment period and 33 (94.3%) completed the posttreatment period. Mean change from baseline over the treatment period for three of the four key efficacy endpoints showed greater improvement in the linaclotide 72 µg group versus placebo. A dose-response trend was seen for stool consistency in patients receiving linaclotide. Four patients randomized to linaclotide experienced treatment-emergent AEs, one of which was treatment-related (mild diarrhea). All AEs were mild or moderate and none were severe. CONCLUSIONS: Linaclotide was well tolerated in this pediatric population and an efficacy trend was seen with linaclotide 72 µg versus placebo.

Randomized controlled trial of linaclotide in children aged 6-17 years with functional constipation.

OBJECTIVES: Linaclotide, a guanylate cyclase-C agonist, was recently approved in the United States for treatment of children 6-17 years old with functional constipation (FC). This study evaluated the safety and efficacy of several linaclotide doses in children 6-17 years old with FC. METHODS: In this multicenter, randomized, double-blind, placebo-controlled phase 2 study, 173 children with FC (based on Rome III criteria) were randomized to once-daily linaclotide (A: 9 or 18 µg, B: 18 or 36 µg, or C: 36 or 72 µg) or placebo in a 1:1:1:1 ratio for 6- to 11-year-olds (dosage determined by weight: 18 to <35 or ≥35 kg) and linaclotide (18, 36, 72, or 145 µg) or placebo in a 1:1:1:1:1 ratio for 12- to 17-year-olds. The primary efficacy endpoint was change from baseline in weekly spontaneous bowel movement (SBM) frequency throughout the 4-week treatment period. Adverse events (AE), clinical laboratory values, and electrocardiograms were monitored. RESULTS: Efficacy and safety were assessed in 173 patients (52.0% aged 6-11 years; 48.0% aged 12-17 years); 162 (93.6%) completed the treatment period. A numerical improvement in mean SBM frequency was observed with increasing linaclotide doses (1.90 in 6- to 11-year-olds [36 or 72 µg] and 2.86 in 12- to 17-year-olds [72 µg]). The most reported treatment-emergent AE was diarrhea, with most cases being mild; none were severe. CONCLUSIONS: Linaclotide was well tolerated in this pediatric population, with a trend toward efficacy in the higher doses, warranting further evaluation.

Nonanaphylactic Variant of Alpha-Gal Syndrome as an Etiology for Chronic Gastrointestinal Symptoms in Children.

We report 3 pediatric patients who presented with only nonanaphylactic symptoms of alpha-gal syndrome. This report highlights the necessity of not discounting alpha-gal syndrome from a differential diagnosis for patients with recurrent gastrointestinal distress and emesis after consuming mammalian meat, even in the absence of an anaphylactic reaction.

A population physiologically-based pharmacokinetic model to characterize antibody disposition in pediatrics and evaluation of the model using infliximab.

AIMS: In order to better predict the pharmacokinetics (PK) of antibodies in children, and to facilitate dose optimization of antibodies in paediatric patients, there is a need to develop systems PK models that integrate ontogeny-related changes in human physiological parameters. METHODS: A population-based physiological-based PK (PBPK) model to characterize antibody PK in paediatrics has been developed, by incorporating age-related changes in body weight, organ weight, organ blood flow rate and interstitial volumes in a previously published platform model. The model was further used to perform Monte Carlo simulations to investigate clearance vs. age and dose-exposure relationships for infliximab. RESULTS: By estimating only one parameter and associated interindividual variability, the model was able to characterize clinical PK of infliximab from two paediatric cohorts (n = 141, 4-19 years) reasonably well. Model simulations demonstrated that only 50% of children reached desired trough concentrations when receiving FDA-labelled dosing regimen for infliximab, suggesting that higher doses and/or more frequent dosing are needed to achieve target trough concentrations of this antibody. CONCLUSION: The paediatric PBPK model presented here can serve as a framework to characterize the PK of antibodies in paediatric patients. The model can also be applied to other protein therapeutics to advance precision medicine paradigm and optimize antibody dosing regimens in children.

Obese Children Require Lower Doses of Pantoprazole Than Nonobese Peers to Achieve Equal Systemic Drug Exposures.

OBJECTIVE: To assess appropriate pantoprazole dosing for obese children, we conducted a prospective pharmacokinetics (PK) investigation of pantoprazole in obese children, a patient population that is traditionally excluded from clinical trials. STUDY DESIGN: A total of 41 obese children (6-17 years of age), genotyped for CYP2C19 variants *2, *3, *4, and *17, received a single oral dose of pantoprazole, ~1.2 mg/kg lean body weight (LBW), with LBW calculated via a validated formula. Ten post-dose pantoprazole plasma concentrations were measured, and PK variables generated via noncompartmental methods (WinNonlin). Linear and nonlinear regression analyses and analyses of variance were used to explore obesity, age, and CYP2C19 genotype contribution to pantoprazole PK. PK variables of interest were compared with historic nonobese peers treated with pantoprazole. RESULTS: Independent of genotype, when normalized to dose per kg total body weight, pantoprazole apparent clearance and apparent volume of distribution were significantly lower (P < .05) and systemic exposure significantly higher (P < .01) in obese vs nonobese children. When normalized per kg LBW, these differences were not evident in children ≥12 years of age and markedly reduced in children <12 years of age. CONCLUSIONS: LBW dosing of pantoprazole led to pantoprazole PK similar to nonobese peers. Additional factors, other than body size (eg, age-related changes in CYP2C19 activity), appear to affect pantoprazole PK in children <12 years of age. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02186652.

Decreased Pregnane X Receptor Expression in Children with Active Crohn's Disease.

Expression of the pregnane X receptor (PXR) has been reported to be decreased in animal models of inflammatory bowel disease (IBD). To investigate the differential expression of PXR in children with Crohn's disease, a type of IBD, RNA was extracted from archived intestinal biopsies from 18 children with Crohn's disease (CD) and 12 age- and sex-matched controls (aged 7-17yrs). The aim of this investigation was to compare the relative mRNA expression of PXR, cytochrome p450 3A4 (CYP3A4), and villin 1 (VIL1) (a marker of epithelial cell integrity) in the inflamed terminal ileum (TI) versus noninflamed duodenum of children with CD. Relative expression was determined via reverse transcription real-time quantitative polymerase chain reaction, data normalized to glyceraldehyde 3-phosphate dehydrogenase, and differences in gene expression explored via paired t tests. PXR expression was decreased in the inflamed TI versus noninflamed duodenum (TI = 1.88 ± 0.89 versus duodenum = 2.5 ± 0.67; P < 0.001) in CD, but not controls (TI = 2.11 ± 0.41 versus duodenum = 2.26 ± 0.61; P = 0.52). CYP3A4 expression was decreased in CD (TI = -0.89 ± 3.11 versus duodenum = 1.90 ± 2.29; P < 0.05), but not controls (TI = 2.46 ± 0.51 versus duodenum = 2.60 ± 0.60; P = 0.61), as was VIL1 (CD TI = 3.80 ± 0.94 versus duodenum = 4.61 ± 0.52; P < 0.001; controls TI = 4.30 ± 0.35 versus duodenum = 4.47 ± 0.40; P = 0.29). PXR expression correlated with VIL1 (r = 0.78, P = 0.01) and CYP3A4 (r = 0.52, P = 0.01) expression. In conclusion, PXR, CYP3A4, and VIL1 expression was decreased only in the actively inflamed small intestinal tissue in children with CD. Our findings suggest that inflammation has the potential to influence expression of genes, and potentially intestinal proteins, important to drug disposition and response. The observed differential patterns of gene expression support further investigation of the role of PXR in the pathogenesis and/or treatment of pediatric Crohn's disease.

Investigation of potential early Histologic markers of pediatric inflammatory bowel disease.

BACKGROUND: Early manifestations of pediatric inflammatory bowel disease (IBD) can be relatively nonspecific. Initial mucosal biopsies may not be conclusive, delaying the diagnosis until subsequent biopsies demonstrate typical histologic features of IBD. We hypothesized that certain inflammatory cell types may be utilized as early histologic indicators of IBD in children. METHODS: A retrospective analysis compared histologic findings from initially inconclusive or negative endoscopic studies in 22 patients who were subsequently diagnosed with IBD (after diagnostic endoscopy) to those of 20 comparison patients with functional abdominal pain matched for age, gender, and study type. A pediatric pathologist, blinded to study group, reviewed biopsies for histologic abnormalities. Eosinophil densities were obtained from the stomach, duodenum, and rectosigmoid areas. Immunohistochemistry (IHC) staining for tumor necrosis factor-α (TNF-α) and matrix metalloproteinase-9 (MMP-9) was performed on the stomach and rectosigmoid areas. RESULTS: Gastritis and colonic crypt distortion were present in the IBD group at a greater rate (61 % vs. 22 %, p = 0.020; 34 % vs. 4 %, p = 0.008, respectively). Peak and mean eosinophil densities in the rectosigmoid area were greater in the IBD group (17.0/hpf vs. 5.0/hpf, p = 0.0063; 12.3/hpf vs. 4.2/hpf, p = 0.0106, respectively). TNF-α and MMP-9 staining did not reveal any significant differences. CONCLUSIONS: Our data suggests that significantly greater inflammation in the stomach, crypt distortion in the colon, and eosinophilia in the rectosigmoid distinguished the IBD group from the comparison group at the time of the initial endoscopic evaluation.

Delta-S-Cys-Albumin as a Marker of Pediatric Biospecimen Integrity.

Blood plasma storage is a crucial element of pediatric biobanking. Improperly stored or handled specimens (e.g., at > -30°C) can result in altered biomolecular compositions that no longer reflects in vivo reality. We report application of a previously developed assay in adults-the ΔS-Cys-Albumin assay, which facilitates estimation of plasma and serum exposure to thawed conditions-to a population of pediatric EDTA plasma samples from patients aged 3-18 years to determine the assay's applicability, estimate its reference range for pediatric samples, and assess the impact of pre-centrifugation delay at 0°C. In addition, the effect of plasma thawed-state exposure to a range of times at 23°C, 4°C, and -20°C on ΔS-Cys-Albumin was evaluated. Using 98 precollected and processed pediatric EDTA plasma specimens, no difference was found in ΔS-Cys-Albumin under conditions of pre-centrifugation delay for up to 10 hours at 0°C. This lack of change allowed us to estimate a pediatric reference range for ΔS-Cys-Albumin of 7.0%-22.5% (mean of 12.8%) with a modest Pearson correlation between ΔS-Cys-Albumin and age (p = 0.0037, R2 = 0.29). ΔS-Cys-Albumin stability in six specimens at 23°C, 4°C, and -20°C was also evaluated. Plateaus in the decay curves were reached by 1 day, 7 days, and 14-28 days at these respective temperatures. The estimated pediatric reference range observed in children was lower than that previously observed in 180 adults of 12.3%-30.6% (mean of 20.0%), and the slope of the age correlation in children was twice as steep as that from adults. ΔS-Cys-Albumin decay curves at 23°C, 4°C, and -20°C were similar to those previously observed in adults. The data reported here support the use of ΔS-Cys-Albumin in evaluating the integrity and overall exposure of pediatric EDTA plasma specimens to thawed conditions. In doing so, they add an important quality control tool to the biobanker's arsenal.

Influence of novel CYP2C-haplotype on proton pump inhibitor pharmacokinetics in children.

In this brief report, we provide an analysis of the influence of a novel CYP2C haplotype (CYP2C:TG) on proton pump inhibitor (PPI) pharmacokinetics (PK) in children. The CYP2C:TG haplotype has been proposed to be associated with increased CYP2C19 activity. We sought to determine if this CYP2C:TG haplotype resulted in similar alterations in metabolism for proton pump inhibitors, which are primarily metabolized by CYP2C19. In a cohort of 41 children aged 6-21 participating in a PPI pharmacokinetic study, effects of the CYP2C:TG allele were assessed by fitting two linear regression models for each of the six PK outcomes assessed, the second of which accounted for the presence of the CYP2C:TG allele. The difference in R2 values between the two models was computed to quantify the variability in the outcome that could be accounted for by the CYP2C:TG allele after adjustment for the CYP2C19 genotype. We found the CYP2C:TG haplotype to have no measurable additive impact on CYP2C19-mediated metabolism of PPIs in vivo in older children and adolescents. The findings of this study do not support the clinical utility of routine testing for the CYP2C:TG haplotype to guide PPI dose adjustments in children.

Physiologically-based pharmacokinetic modeling of pantoprazole to evaluate the role of CYP2C19 genetic variation and obesity in the pediatric population.

Pantoprazole is a proton pump inhibitor indicated for the treatment of gastroesophageal reflux disease, a condition that disproportionately affects children with obesity. Appropriately dosing pantoprazole in children with obesity requires understanding the body size metric that best guides dosing, but pharmacokinetic (PK) trials using traditional techniques are limited by the need for larger sample sizes and frequent blood sampling. Physiologically-based PK (PBPK) models are an attractive alternative that can account for physiologic-, genetic-, and drug-specific changes without the need for extensive clinical trial data. In this study, we explored the effect of obesity on pantoprazole PK and evaluated label-suggested dosing in this population. An adult PBPK model for pantoprazole was developed using data from the literature and accounting for genetic variation in CYP2C19. The adult PBPK model was scaled to children without obesity using age-associated changes in anatomical and physiological parameters. Lastly, the pediatric PBPK model was expanded to children with obesity. Three pantoprazole dosing strategies were evaluated: 1 mg/kg total body weight, 1.2 mg/kg lean body weight, and US Food and Drug Administration-recommended weight-tiered dosing. Simulated concentration-time profiles from our model were compared with data from a prospective cohort study (PAN01; NCT02186652). Weight-tiered dosing resulted in the most (>90%) children with pantoprazole exposures in the reference range, regardless of obesity status or CYP2C19 phenotype, confirming results from previously published population PK models. PBPK models may allow for the efficient study of physiologic and developmental effects of obesity on PK in special populations where clinical trial data may be limited.

A Pilot Study of Ketotifen in Patients Aged 8-17 Years with Functional Dyspepsia Associated with Mucosal Eosinophilia.

BACKGROUND AND OBJECTIVE: Mast cells have been implicated in abdominal pain-associated disorders of gut-brain interaction, such as functional dyspepsia. As such, ketotifen, a second-generation antihistamine and mast cell stabilizer, could represent a viable treatment option in these conditions. The primary aim of the current pilot study was to assess clinical response to ketotifen and assess pharmacokinetics in youth with functional dyspepsia. METHODS: We conducted a pilot randomized, double-blind, placebo-controlled, cross-over trial of ketotifen in 11 youth with functional dyspepsia and duodenal mucosal eosinophilia with 4 weeks of active treatment at a dose of 1 mg twice daily. Global clinical response was graded on a 5-point Likert Scale. A single plasma sample was obtained at steady state for pharmacokinetic analysis. RESULTS: Ketotifen was not superior to placebo with regard to global clinical response. Only 18% of patients demonstrated a complete or near-complete clinical response. The estimated half-life was 3.3 h. CONCLUSIONS: While ketotifen was not superior to placebo, this study highlights several important challenges for developing drug trials for youth with chronic abdominal pain. Recommendations are made for designing a larger treatment trial for ketotifen in this patient group. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov: NCT02484248.

Anti-TNF, infliximab, and adalimumab can be effective in eosinophilic bowel disease.

BACKGROUND: Eosinophilic enterocolitis (EEC) is an emerging distinct inflammatory bowel disease of unknown etiology. There are no published data on the effect of infliximab (IFX) or adalimumab (ADA) for the treatment of refractory cases. METHODS: A report of all pediatric cases with EEC treated with anti-tumor necrosis factor, identified after an open international call. RESULTS: We describe here the first 8 children with refractory EEC who were treated with IFX (75% boys; mean age at diagnosis 8.6 ± 4.03 [range 1.6-14 years]; mean age at IFX treatment 11.7 ± 4.4 [range 4.2-16 years]). Allergic and infectious causes of EEC were excluded in all cases. Rapid and complete clinical remission was documented in 6 (75%) children following the induction infusions: 3 (38%) with endoscopic remission, 2 (25%) with endoscopic improvement, and 1 unknown. Four of the 6 responders had secondary loss of response and were switched to ADA, 3 of whom with sustained remission using high doses. Overall, the 6 responders were followed for a median of 7 years (range 4-12; interquartile range 6.4-8.8 years) without evidence of developing Crohn disease or ulcerative colitis. The only case with macroscopic findings on endoscopy was a primary nonresponder. CONCLUSIONS: IFX and ADA may be effective in cases of refractory idiopathic EEC; however, because this is an uncontrolled report, further prospective studies are warranted.

Effects of obesity on the pharmacology of proton pump inhibitors: current understanding and future implications for patient care and research.

INTRODUCTION: In the United States, obesity affects approximately ⅖ adults and ⅕ children, leading to increased risk for comorbidities, like gastroesophageal reflux disease (GERD), treated increasingly with proton pump inhibitors (PPIs). Currently, there are no clinical guidelines to inform PPI dose selection for obesity, with sparse data regarding whether dose augmentation is necessary. AREAS COVERED: We provide a review of available literature regarding the pharmacokinetics (PK), pharmacodynamics (PD), and/or metabolism of PPIs in children and adults with obesity, as a step toward informing PPI dose selection. EXPERT OPINION: Published PK data in adults and children are limited to first-generation PPIs and point toward reduced apparent oral drug clearance in obesity, with equipoise regarding obesity impact on drug absorption. Available PD data are sparse, conflicting, and limited to adults. No studies are available to inform the PPI PK→PD relationship in obesity and if/how it differs compared to individuals without obesity. In the absence of data, best practice may be to dose PPIs based on CYP2C19 genotype and lean body weight, so as to avoid systemic overexposure and potential toxicities, while monitoring closely for efficacy.

Pharmacogenetic Testing for the Pediatric Gastroenterologist: Actionable Drug-Gene Pairs to Know.

Gastroenterologists represent some of the earlier adopters of precision medicine through pharmacogenetic testing by embracing upfront genotyping for thiopurine S-methyltransferase nucleotide diphosphatase (TPMT) before prescribing 6-mercaptopurine or azathioprine for the treatment of inflammatory bowel disease. Over the last two decades, pharmacogenetic testing has become more readily available for other genes relevant to drug dose individualization. Common medications prescribed by gastroenterologists for conditions other than inflammatory bowel disease now have actionable guidelines, which can improve medication efficacy and safety; however, a clear understanding of how to interpret the results remains a challenge for many clinicians, precluding wide implementation of genotype-guided dosing for drugs other than 6-mercaptopurine and azathioprine. Our goal is to provide a practical tutorial on the currently available pharmacogenetic testing options and a results interpretation for drug-gene pairs important to medications commonly used in pediatric gastroenterology. We focus on evidence-based clinical guidelines published by the Clinical Pharmacogenetics Implementation Consortium (CPIC®) to highlight relevant drug-gene pairs, including proton pump inhibitors and selective serotonin reuptake inhibitors and cytochrome P450 (CYP) 2C19, ondansetron and CYP2D6, 6-mercaptopurine and TMPT and Nudix hydrolase 15 (NUDT15), and budesonide and tacrolimus and CYP3A5.

Impact of Duodenal Pathology on Oral Drug Bioavailability and Disease Outcomes in Pediatric Crohn's Disease.

BACKGROUND: Crohn's disease with upper gastrointestinal tract involvement occurs more often in children than adults and has the potential to interfere with oral drug absorption. We aimed to compare disease outcomes in children receiving oral azathioprine for the treatment of Crohn's disease with (DP) and without (NDP) duodenal pathology at diagnosis. METHODS: Duodenal villous length, body mass index (BMI), and laboratory studies were compared in DP vs. NDP during the first year post-diagnosis, using parametric/nonparametric tests and regression analysis (SAS v9.4); the data are reported as the median (interquartile range) or the mean ± standard deviation. Thiopurine metabolite concentration (pmol/8 × 108 erythrocytes) 230-400 was considered therapeutic for 6-thioguanine nucleotides (6-TGN), and >5700 was considered hepatotoxic for 6-methylmercaptopurine (6-MMPN). RESULTS: Twenty-six of the fifty-eight children enrolled (29 DP, 29 NDP) started azathioprine for standard medical care, including nine DP and ten NDP who had normal thiopurine methyltransferase activity. Duodenal villous length was significantly shorter in DP vs. NDP (342 ± 153 vs. 460 ± 85 µm; p < 0.001) at diagnosis; age, sex, hemoglobin, and BMI were comparable between groups. A trend toward lower 6-TGN was observed in the DP vs. NDP subset receiving azathioprine (164 (117, 271) vs. 272 (187, 331); p = 0.15). Compared to NDP, DP received significantly higher azathioprine doses (2.5 (2.3, 2.6) vs. 2.2 (2.0, 2.2) mg/kg/day; p = 0.01) and had an increased relative risk of sub-therapeutic 6-TGN. At 9 months post-diagnosis, children with DP had significantly lower hemoglobin (12.5 (11.7, 12.6) vs. 13.1 (12.7, 13.3) g/dL; p = 0.01) and BMI z-scores (-0.29 (-0.93, -0.11) vs. 0.88 (0.53, 0.99); p = 0.02) than children with NDP. CONCLUSION: For children with Crohn's disease, duodenal pathology, marked by villous blunting, increased the risk of sub-therapeutic 6-TGN levels, despite higher azathioprine dosing during the first year post-diagnosis. Lower hemoglobin and BMI z-scores at 9 months post-diagnosis suggest the impaired absorption/bioavailability of nutrients, as well as oral drugs, in children with duodenal disease.

Pediatric growth patterns in youth-onset type 2 diabetes mellitus: Implications for physiologically-based pharmacokinetic models.

An accurate understanding of the changes in height and weight of children with age is critical to the development of models predicting drug concentrations in children (i.e., physiologically-based pharmacokinetic models). However, curves describing the growth of a typical population of children may not accurately characterize growth of children with various conditions, such as obesity. Therefore, to develop height and weight versus age growth curves for youth who were diagnosed with type 2 diabetes, we extracted data from electronic medical records. Robust nonlinear models were parameterized to the equations describing height and weight versus age as defined by the Centers for Disease Control and Prevention (CDC). CDC z-scores were calculated using an internal program. The growth curves and z-scores were compared to CDC norms. Youth with type 2 diabetes were increasingly heavier than CDC norms from early childhood. Except for a period around puberty, youth with type 2 diabetes were, on average, shorter than CDC norms, resulting in shorter average adult height. Deviations in growth were apparent in youth who develop type 2 diabetes; such deviations may be expected for other conditions as well, and disease-specific growth curves should be considered during development of model-informed drug development for pediatric conditions.

Characterization of the Mucosally-Adherent Duodenal Microbiome in Children with and without Crohn's Disease.

Manipulation of the microbiome is a rational treatment strategy for inflammatory bowel disease (IBD). Compared to the colon and terminal ileum (TI), understanding of the microbial composition in the duodenum is sparse. This gap in knowledge is especially significant for children with Crohn's disease (CD) because the prevalence of duodenal CD is higher in children than in adults. Our aim was to characterize the bacterial composition of the mucosally-adherent duodenal microbiome in children with and without CD as a first step toward development of targeted IBD treatment strategies at this disease location. Fresh-frozen mucosal biopsies were obtained from the duodenum and TI of children with treatment-naïve CD and age- and sex-matched controls. Extracted DNA was analyzed for sequence variation in the 16S ribosomal RNA bacterial gene region V4 (Novogene; Beijing, China). Bacterial relative abundance, alpha and beta composition, and diversity, were compared across duodenal and TI samples from the controls and CD groups with and without chronic active inflammation (118 samples from 73 children total; approx. 50% CD), using UniFrac dissimilarity coefficients (α < 0.05), Linear Discriminant Analysis Effect Size (LEfSe) analysis (LDA score ≥ 2), and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) analysis. The relationships between bacterial abundance, sex, age, concomitant medication use, and villous length were assessed. The microbial composition in the duodenum was significantly different from the TI in the control population(R-value = 0.558, p = 0.001) and in children with active CD (R-value = 0.301, p = 0.001). Significant differences in bacterial abundance were noted between the control and CD duodena (LDA > 4). The duodenum of children without CD was characterized by increased abundance in Pseudomonodales, whereas the actively inflamed duodenum in CD was characterized by increased abundance of Bacteroidales, specifically the family Prevotellaceae. This trend is opposite of previously published observations of microbial composition in the TI, where active inflammation was associated with a relative decrease in the abundance of Bacteroidetes and an increase in Proteobacteria, including Pseudomonadales. No statistically significant correlations were noted between abundance and age, sex, concomitant medication use or villous length, except for Bacteroidetes, which significantly decreased in abundance in the TI with age (p = 0.048). The pediatric duodenal microbiome is distinct from the TI and characterized by an increased abundance of Pseudomonodales and Spirochetes in healthy children, and an increased abundance of Bacteroidales in active CD patients.