Clinical and biological predictors of response to standardised paediatric colitis therapy (PROTECT): a multicentre inception cohort study

BACKGROUND

Lack of evidence-based outcomes data leads to uncertainty in developing treatment regimens in children who are newly diagnosed with ulcerative colitis. We hypothesised that pretreatment clinical, transcriptomic, and microbial factors predict disease course.

METHODS

In this inception cohort study, we recruited paediatric patients aged 4-17 years with newly diagnosed ulcerative colitis from 29 centres in the USA and Canada. Patients initially received standardised mesalazine or corticosteroids, with pre-established criteria for escalation to immunomodulators (ie, thiopurines) or anti-tumor necrosis factor-α (TNFα) therapy. We used RNA sequencing to define rectal gene expression before treatment, and 16S sequencing to characterise rectal and faecal microbiota. The primary outcome was week 52 corticosteroid-free remission with no therapy beyond mesalazine. We assessed factors associated with the primary outcome using logistic regression models of the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT01536535.

FINDINGS

Between July 10, 2012, and April 21, 2015, of 467 patients recruited, 428 started medical therapy, of whom 400 (93%) were evaluable at 52 weeks and 386 (90%) completed the study period with no protocol violations. 150 (38%) of 400 participants achieved week 52 corticosteroid-free remission, of whom 147 (98%) were taking mesalazine and three (2%) were taking no medication. 74 (19%) of 400 were escalated to immunomodulators alone, 123 (31%) anti-TNFα therapy, and 25 (6%) colectomy. Low baseline clinical severity, high baseline haemoglobin, and week 4 clinical remission were associated with achieving week 52 corticosteroid-free remission (n=386, logistic model area under the curve [AUC] 0·70, 95% CI 0·65-0·75; specificity 77%, 95% CI 71-82). Baseline severity and remission by week 4 were validated in an independent cohort of 274 paediatric patients with newly diagnosed ulcerative colitis. After adjusting for clinical predictors, an antimicrobial peptide gene signature (odds ratio [OR] 0·57, 95% CI 0·39-0·81; p=0·002) and abundance of Ruminococcaceae (OR 1·43, 1·02-2·00; p=0·04), and Sutterella (OR 0·81, 0·65-1·00; p=0·05) were independently associated with week 52 corticosteroid-free remission.

INTERPRETATION

Our findings support the utility of initial clinical activity and treatment response by 4 weeks to predict week 52 corticosteroid-free remission with mesalazine alone in children who are newly diagnosed with ulcerative colitis. The development of personalised clinical and biological signatures holds the promise of informing ulcerative colitis therapeutic decisions.

FUNDING

US National Institutes of Health.

Biologics Delay Progression of Crohn's Disease, but Not Early Surgery, in Children

BACKGROUND & AIMS

Up to 30% of patients with Crohn's disease (CD) require surgery within the first 5 years from diagnosis. We investigated the recent risk of bowel surgery in an inception cohort of pediatric patients with CD and whether early use of biologics (tumor necrosis factor antagonists) alters later disease course.

METHODS

We collected data from the Pediatric Inflammatory Bowel Disease Collaborative Research Group registry on 1442 children (age, ≤16 y) diagnosed with CD from January 2002 through December 2014. Data were collected at diagnosis, 30 days following diagnosis, and then quarterly and during hospitalizations for up to 12 years. Our primary aim was to determine the 10-year risk for surgery in children with CD. Our secondary aim was to determine whether early use of biologics (<3 mo of diagnosis) affected risk of disease progression.

RESULTS

The 10-year risk of first bowel surgery was 26%. The 5-year risk of bowel surgery did not change from 2002 through 2014, and remained between 13% and 14%. Most surgeries occurred within 3 years from diagnosis. The only predictor of surgery was disease behavior at diagnosis. CD with inflammatory behavior had the lowest risk of surgery compared to stricturing disease, penetrating disease, or both. We associated slowing of disease progression to stricturing or penetrating disease (but not surgery) with early use of biologics, but this effect only became evident after 5 years of disease. Our results indicate that biologics slow disease progression over time (hazard ratio, 0.85; 95% CI, 0.76-0.95).

CONCLUSIONS

In an analysis of data from a registry of pediatric patients with CD, we found that among those with significant and progressing disease at or shortly after presentation, early surgery is difficult to prevent, even with early use of biologics. Early use of biologics (<3 mo of diagnosis) can delay later disease progression to stricturing and/or penetrating disease, but this affect could become evident only years after initial management decisions are made.

Serologic Reactivity Reflects Clinical Expression of Ulcerative Colitis in Children

Background

In contrast to pediatric Crohn's disease (CD), little is known in pediatric ulcerative colitis (UC) about the relationship between disease phenotype and serologic reactivity to microbial and other antigens.

Aim

The aim of this study was to examine disease phenotype and serology in a well-characterized inception cohort of children newly diagnosed with UC during the PROTECT Study (Predicting Response to Standardized Pediatric Colitis Therapy).

Methods

Patients were recruited from 29 participating centers. Demographic, clinical, laboratory, and serologic (pANCA, ASCA IgA/IgG, Anti-CBir1, and Anti-OmpC) data were obtained from children 4-17 years old with UC.

Results

Sixty-five percent of the patients had positive serology for pANCA, with 62% less than 12 years old and 66% 12 years old or older. Perinuclear anti-neutrophil cytoplasmic antibodies did not correspond to a specific phenotype though pANCA ≥100, found in 19%, was strongly associated with pancolitis (P = 0.003). Anti-CBir1 was positive in 19% and more common in younger children with 32% less than 12 years old as compared with 14% 12 years old or older (P < 0.001). No association was found in any age group between pANCA and Anti-CBir1. Relative rectal sparing was more common in +CBir1, 16% versus 7% (P = 0.02). Calprotectin was lower in Anti-CBir1+ (Median [IQR] 1495 mcg/g [973-3333] vs 2648 mcg/g [1343-4038]; P = 0.04). Vitamin D 25-OH sufficiency was associated with Anti-CBir1+ (P = 0.0009).

Conclusions

The frequency of pANCA in children was consistent with adult observations. High titer pANCA was associated with more extensive disease, supporting the idea that the magnitude of immune reactivity may reflect disease severity. Anti-CBir1+ was more common in younger ages, suggesting host-microbial interactions may differ by patient age.

Free and Bioavailable 25-Hydroxyvitamin D Concentrations are Associated With Disease Activity in Pediatric Patients With Newly Diagnosed Treatment Naïve Ulcerative Colitis

BACKGROUND

Vitamin D regulates intestinal epithelial and immune functions, and vitamin D receptor deficiency increases the severity of murine colitis. Bioavailable 25-hydroxyvitamin D (25(OH)D) is available to target tissues and may be a driver of immune function. The aim is to evaluate the relationship of bioavailable 25(OH)D to the clinical expression of treatment naive pediatric ulcerative colitis (UC).

METHODS

The PROTECT (Predicting Response to Standardized Pediatric Colitis Therapy) study enrolled children ≤17 years newly diagnosed with UC. Free and total 25(OH)D were directly measured and 25(OH)D fractions were compared with disease activity measures.

RESULTS

Data were available on 388 subjects, mean age 12.7 years, 49% female, 84% with extensive/pancolitis. The median (IQR) total 25(OH)D concentration was 28.5 (23.9, 34.8) ng/mL, and 57% of subjects demonstrated insufficient vitamin D status (25(OH)D < 30 ng/mL). We found no evidence of association between total 25(OH)D and disease activity. Regression models adjusted for age, sex, race, and ethnicity demonstrated that an increase from 25th to 75th percentile for bioavailable and free 25(OH)D were associated with a mean (95th CI) decrease in the Pediatric Ulcerative Colitis Activity Index (PUCAI) of -8.7 (-13.7, -3.6) and -3.1 (-5.0, -1.2), respectively. No associations were detected between 25(OH)D fractions and fecal calprotectin or Mayo endoscopy score.

CONCLUSIONS

Vitamin D insufficiency is highly prevalent in children with newly diagnosed UC. We found associations of free and bioavailable, but not total 25(OH)D, with PUCAI. Bioavailable vitamin D may contribute to UC pathophysiology and clinical activity.

Long ncRNA Landscape in the Ileum of Treatment-Naive Early-Onset Crohn Disease

BACKGROUND

Long noncoding RNAs (lncRNA) are key regulators of gene transcription and many show tissue-specific expression. We previously defined a novel inflammatory and metabolic ileal gene signature in treatment-naive pediatric Crohn disease (CD). We now extend our analyses to include potential regulatory lncRNA.

METHODS

Using RNAseq, we systematically profiled lncRNAs and protein-coding gene expression in 177 ileal biopsies. Co-expression analysis was used to identify functions and tissue-specific expression. RNA in situ hybridization was used to validate expression. Real-time polymerase chain reaction was used to test lncRNA regulation by IL-1β in Caco-2 enterocytes.

RESULTS

We characterize widespread dysregulation of 459 lncRNAs in the ileum of CD patients. Using only the lncRNA in discovery and independent validation cohorts showed patient classification as accurate as the protein-coding genes, linking lncRNA to CD pathogenesis. Co-expression and functional annotation enrichment analyses across several tissues and cell types 1showed that the upregulated LINC01272 is associated with a myeloid pro-inflammatory signature, whereas the downregulated HNF4A-AS1 exhibits association with an epithelial metabolic signature. We confirmed tissue-specific expression in biopsies using in situ hybridization, and validated regulation of prioritized lncRNA upon IL-1β exposure in differentiated Caco-2 cells. Finally, we identified significant correlations between LINC01272 and HNF4A-AS1 expression and more severe mucosal injury.

CONCLUSIONS

We systematically define differentially expressed lncRNA in the ileum of newly diagnosed pediatric CD. We show lncRNA utility to correctly classify disease or healthy states and demonstrate their regulation in response to an inflammatory signal. These lncRNAs, after mechanistic exploration, may serve as potential new tissue-specific targets for RNA-based interventions.

Factors associated with early outcomes following standardised therapy in children with ulcerative colitis (PROTECT): a multicentre inception cohort study

BACKGROUND

Previous retrospective studies of paediatric ulcerative colitis have had limited ability to describe disease progression and identify predictors of treatment response. In this study, we aimed to identify characteristics associated with outcomes following standardised therapy after initial diagnosis.

METHODS

The PROTECT multicentre inception cohort study was based at 29 centres in the USA and Canada and included paediatric patients aged 4-17 years who were newly diagnosed with ulcerative colitis. Guided by the Pediatric Ulcerative Colitis Activity Index (PUCAI), patients received initial standardised treatment with mesalazine (PUCAI 10-30) oral corticosteroids (PUCAI 35-60), or intravenous corticosteroids (PUCAI ≥65). The key outcomes for this analysis were week 12 corticosteroid-free remission, defined as PUCAI less than 10 and taking only mesalazine, and treatment escalation during the 12 study weeks to anti-tumour necrosis factor α (TNFα) agents, immunomodulators, or colectomy among those initially treated with intravenous corticosteroids. We identified independent predictors of outcome through multivariable logistic regression using a per-protocol approach. This study is registered with ClinicalTrials.gov, number NCT01536535.

FINDINGS

Patients were recruited between July 10, 2012, and April 21, 2015. 428 children initiated mesalazine (n=136), oral corticosteroids (n=144), or intravenous corticosteroids (n=148). Initial mean PUCAI was 31·1 (SD 13·3) in children initiating with mesalazine, 50·4 (13·8) in those initiating oral corticosteroids, and 66·9 (13·7) in those initiating intravenous corticosteroids (p<0·0001 for between-group comparison). Week 12 outcome data were available for 132 patients who initiated with mesalazine, 141 with oral corticosteroids, and 143 with intravenous corticosteroids. Corticosteroid-free remission with the patient receiving mesalazine treatment only at 12 weeks was achieved by 64 (48%) patients in the mesalazine group, 47 (33%) in the oral corticosteroid group, and 30 (21%) in the intravenous corticosteroid group (p<0·0001). Treatment escalation was required by nine (7%) patients in the mesalazine group, 21 (15%) in the oral corticosteroid group, and 52 (36%) in the intravenous corticosteroid group (p<0·0001). Eight patients, all of whom were initially treated with intravenous corticosteroids, underwent colectomy. Predictors of week 12 corticosteroid-free remission were baseline PUCAI less than 35 (odds ratio 2·44, 95% CI 1·41-4·22; p=0·0015), higher baseline albumin by 1 g/dL increments among children younger than 12 years (4·05, 1·90-8·64; p=0·00030), and week 4 remission (6·26, 3·79-10·35; p<0·0001). Predictors of treatment escalation by week 12 in patients initially treated with intravenous corticosteroids included baseline total Mayo score of 11 or higher (2·59, 0·93-7·21; p=0·068 [retained in model due to clinical relevance]), rectal biopsy eosinophil count less than or equal to 32 cells per high power field (4·55, 1·62-12·78; p=0·0040), rectal biopsy surface villiform changes (3·05, 1·09-8·56; p=0·034), and not achieving week 4 remission (30·28, 6·36-144·20; p<0·0001).

INTERPRETATION

Our findings provide guidelines to assess the response of children newly diagnosed with ulcerative colitis to standardised initial therapy and identify predictors of treatment response and failure. These data suggest that additional therapeutic interventions might be warranted to improve early outcomes, especially in patients presenting with severe disease and requiring intravenous corticosteroids.

FUNDING

National Institutes of Health.

Dissecting Allele Architecture of Early Onset IBD Using High-Density Genotyping

Background

The inflammatory bowel diseases (IBD) are common, complex disorders in which genetic and environmental factors are believed to interact leading to chronic inflammatory responses against the gut microbiota. Earlier genetic studies performed in mostly adult population of European descent identified 163 loci affecting IBD risk, but most have relatively modest effect sizes, and altogether explain only ~20% of the genetic susceptibility. Pediatric onset represents about 25% of overall incident cases in IBD, characterized by distinct disease physiology, course and risks. The goal of this study is to compare the allelic architecture of early onset IBD with adult onset in population of European descent.

Methods

We performed a fine mapping association study of early onset IBD using high-density Immunochip genotyping on 1008 pediatric-onset IBD cases (801 Crohn’s disease; 121 ulcerative colitis and 86 IBD undetermined) and 1633 healthy controls. Of the 158 SNP genotypes obtained (out of the 163 identified in adult onset), this study replicated 4% (5 SNPs out of 136) of the SNPs identified in the Crohn’s disease (CD) cases and 0.8% (1 SNP out of 128) in the ulcerative colitis (UC) cases. Replicated SNPs implicated the well known NOD2 and IL23R. The point estimate for the odds ratio (ORs) for NOD2 was above and outside the confidence intervals reported in adult onset. A polygenic liability score weakly predicted the age of onset for a larger collection of CD cases (p< 0.03, R²= 0.007), but not for the smaller number of UC cases.

Conclusions

The allelic architecture of common susceptibility variants for early onset IBD is similar to that of adult onset. This immunochip genotyping study failed to identify additional common variants that may explain the distinct phenotype that characterize early onset IBD. A comprehensive dissection of genetic loci is necessary to further characterize the genetic architecture of early onset IBD.

Liver enzyme elevations within 3 months of diagnosis of inflammatory bowel disease and likelihood of liver disease

BACKGROUND

Inflammatory bowel disease-associated liver diseases (IBD-LDs) include autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and an overlap syndrome. Prospective unbiased multicenter data regarding the frequency of IBD-LD in patients with pediatric inflammatory bowel disease (IBD) are lacking. We examined early alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (GGT) elevations in children diagnosed as having IBD and assessed the likelihood of IBD-LD.

METHODS

Data collected from the prospective observational Pediatric Inflammatory Bowel Disease Collaborative Research Group Registry enrolling children of age <16 years within 30 days of diagnosis. AIH, PSC, and overlap syndrome were diagnosed using local institutional criteria.

RESULTS

A total of 1569 subjects had liver enzymes available. Of the total, 757 had both ALT and GGT, 800 had ALT only (no GGT), and 12 had GGT only (no ALT). Overall, 29 of 1569 patients (1.8%) had IBD-LD. IBD-LD was diagnosed in 1 of 661 (0.15%) of patients with both ALT and GGT ≤ 50 IU/L compared with 21 of 42 (50%) of patients with both ALT and GGT > 50 (odds ratio 660, P < 0.0001). Of the 29 patients with IBD-LD, 21 had PSC, 2 had AIH, and 6 had overlap syndrome. IBD-LD was more common in patients with ulcerative colitis and IBD-unclassified (indeterminate colitis) than in those with Crohn disease (4% vs 0.8%, respectively, P < 0.001).

CONCLUSIONS

Elevation of both ALT and GGT within 90 days after the diagnosis of IBD is associated with a markedly increased likelihood of IBD-LD. Both ALT and GGT levels should be measured in all of the pediatric patients newly diagnosed as having IBD.

Retrospective cohort study of methotrexate use in the treatment of pediatric Crohn's disease

BACKGROUND

Methotrexate (MTX) use as an alternative to thiopurines in the treatment of Crohn's disease (CD) in children is increasing. This study was undertaken to assess safety and efficacy of MTX in children with CD.

METHODS

Patients treated with MTX with a minimum of 1-year follow-up were identified in the Pediatric IBD Collaborative Research Group Registry, a prospective inception cohort study started in 2002. The clinical efficacy and safety of MTX were analyzed retrospectively.

RESULTS

Two hundred ninety patients treated with MTX were identified. One hundred seventy-two patients received at least 3 months of MTX without thiopurine or biologicals and had ≥1 year of follow-up. Eighty-one of 172 patients (47%) received MTX as first immunomodulator (IMM), of which 22 (27%) achieved ≥12 months of sustained clinical remission without surgery, thiopurine, biologicals, or corticosteroids. Those receiving MTX as second IMM achieved similar remission rate (35%, P = not significant). Fourteen percent received MTX as first IMM in 2002 and 60% in 2010 (P = 0.005). Disease location did not affect outcomes. MTX doses were equivalent in both groups. Fifteen percent of patients developed an alanine aminotransferase >60 international units/liter and 12% developed a white blood cell <4000 cells per microliter while on MTX. Only 4% of these discontinued MTX completely. A small group of 6 centers, which contributed only about one-third of patients with CD in the registry, contributed nearly two-thirds of the patients receiving MTX (P < 0.001).

CONCLUSIONS

MTX use as first choice IMM is increasing in pediatric CD. MTX provided sustained clinical remission in nearly one-third of patients with minimal toxicity. There is large center-to-center variability in its use.

Pediatric Crohn disease patients exhibit specific ileal transcriptome and microbiome signature

Interactions between the host and gut microbial community likely contribute to Crohn disease (CD) pathogenesis; however, direct evidence for these interactions at the onset of disease is lacking. Here, we characterized the global pattern of ileal gene expression and the ileal microbial community in 359 treatment-naive pediatric patients with CD, patients with ulcerative colitis (UC), and control individuals. We identified core gene expression profiles and microbial communities in the affected CD ilea that are preserved in the unaffected ilea of patients with colon-only CD but not present in those with UC or control individuals; therefore, this signature is specific to CD and independent of clinical inflammation. An abnormal increase of antimicrobial dual oxidase (DUOX2) expression was detected in association with an expansion of Proteobacteria in both UC and CD, while expression of lipoprotein APOA1 gene was downregulated and associated with CD-specific alterations in Firmicutes. The increased DUOX2 and decreased APOA1 gene expression signature favored oxidative stress and Th1 polarization and was maximally altered in patients with more severe mucosal injury. A regression model that included APOA1 gene expression and microbial abundance more accurately predicted month 6 steroid-free remission than a model using clinical factors alone. These CD-specific host and microbe profiles identify the ileum as the primary inductive site for all forms of CD and may direct prognostic and therapeutic approaches.

Impact of inflammatory bowel disease and high-dose steroid exposure on pupillary responses to negative information in pediatric depression

OBJECTIVE

To better understand emotional information processing in pediatric inflammatory bowel disease (IBD) and its relationship with depression. Pediatric IBD is associated with higher rates of depression than seen in other physical diseases and in community samples. In systemic inflammation, proinflammatory cytokines have been implicated in altering activity in brain regions known to affect emotion processing and emotion regulation in depression.

METHODS

We examined differences in pupillary responses as a marker of brain function in response to negative emotional information in youths (ages, 8-17 years) with IBD both with (n = 8) and without (n = 15) comorbid depression and who were receiving high-dose steroid treatment. We compared their responses to each other and to depressed youths without IBD (n = 20) and healthy youths (n = 22).

RESULTS

Youths with IBD demonstrated greater pupillary responses to the initial presentation of negative emotional stimuli, regardless of their depression status (p = .05). In contrast, depressed youths, regardless of their IBD status, demonstrated a greater constriction of the pupil 10 seconds to 12 seconds after exposure to negative stimuli. This constriction was associated with greater depressive severity and lower albumin levels.

CONCLUSIONS

IBD may be associated with increased sensitivity to negative emotional stimuli above and beyond depression diagnosis. Depressed youths potentially demonstrate affective blunting, emotional avoidance, or a failure to regulate emotion after exposure to negative emotional information. Thus, there seem to be unique contributions of medical disease and depression to physiological indications of emotional reactivity, but these factors do not seem to interact.

Real-time tool to display the predicted disease course and treatment response for children with Crohn's disease

BACKGROUND

Immunomodulators and biologics are effective treatments for children with Crohn's disease (CD). The challenge of communicating the anticipated disease course with and without therapy to patients and parents is a barrier to the timely use of these agents. The aim of this project was to develop a tool to graphically display the predicted risks of CD and expected benefits of therapy.

METHODS

Using prospectively collected data from 796 pediatric CD patients we developed a model using system dynamics analysis (SDA). The primary model outcome is the probability of developing a CD-related complication. Input variables include patient and disease characteristics, magnitude of serologic immune responses expressed as the quartile sum score (QSS), and exposure to medical treatments.

RESULTS

Multivariate Cox proportional analyses show variables contributing a significant increase in the hazard ratio (HR) for a disease complication include female gender, older age at diagnosis, small bowel or perianal disease, and a higher QSS. As QSS increases, the HR for early use of corticosteroids increases, in contrast to a decreasing HR with early use of immunomodulators, early or late biologics, and early combination therapy. The concordance index for the model is 0.81. Using SDA, results of the Cox analyses are transformed into a simple graph displaying a real-time individualized probability of disease complication and treatment response.

CONCLUSIONS

We have developed a tool to predict and communicate individualized risks of CD complications and how this is modified by treatment. Once validated, it can be used at the bedside to facilitate patient decision making.

Real-time tool to display the predicted disease course and treatment response for children with Crohn's disease

BACKGROUND

Immunomodulators and biologics are effective treatments for children with Crohn's disease (CD). The challenge of communicating the anticipated disease course with and without therapy to patients and parents is a barrier to the timely use of these agents. The aim of this project was to develop a tool to graphically display the predicted risks of CD and expected benefits of therapy.

METHODS

Using prospectively collected data from 796 pediatric CD patients we developed a model using system dynamics analysis (SDA). The primary model outcome is the probability of developing a CD-related complication. Input variables include patient and disease characteristics, magnitude of serologic immune responses expressed as the quartile sum score (QSS), and exposure to medical treatments.

RESULTS

Multivariate Cox proportional analyses show variables contributing a significant increase in the hazard ratio (HR) for a disease complication include female gender, older age at diagnosis, small bowel or perianal disease, and a higher QSS. As QSS increases, the HR for early use of corticosteroids increases, in contrast to a decreasing HR with early use of immunomodulators, early or late biologics, and early combination therapy. The concordance index for the model is 0.81. Using SDA, results of the Cox analyses are transformed into a simple graph displaying a real-time individualized probability of disease complication and treatment response.

CONCLUSIONS

We have developed a tool to predict and communicate individualized risks of CD complications and how this is modified by treatment. Once validated, it can be used at the bedside to facilitate patient decision making.

Factors that determine risk for surgery in pediatric patients with Crohn's disease

BACKGROUND & AIMS

We examined the incidence of Crohn's disease (CD)-related surgery in a multi-center, inception cohort of pediatric patients with CD. We also examined the effect of starting immunomodulator therapy within 30 days of diagnosis.

METHODS

Data from 854 children with CD from the Pediatric Inflammatory Bowel Disease Collaborative Research Group who were diagnosed with CD between 2002 and 2008 were analyzed.

RESULTS

Overall, 76 (9%) underwent a first CD-related surgery, 57 (7%) underwent a first bowel surgery (bowel resection, ostomy, strictureplasty, or appendectomy), and 19 (2%) underwent a first non-bowel surgery (abscess drainage or fistulotomy). The cumulative risks for bowel surgery, non-bowel surgery, and all CD-related surgeries were 3.4%, 1.4%, and 4.8%, respectively, at 1 year after diagnosis and 13.8%, 4.5%, and 17.7%, respectively, at 5 years after diagnosis. Older age at diagnosis, greater disease severity, and stricturing or penetrating disease increased the risk of bowel surgery. Disease between the transverse colon and rectum decreased the risk. Initiation of immunomodulator therapy within 30 days of diagnosis, sex, race, and family history of inflammatory bowel disease did not influence the risk of bowel surgery.

CONCLUSIONS

In an analysis of pediatric patients with CD, the 5-year cumulative risk of bowel surgery was lower than that reported in recent studies of adult and pediatric patients but similar to that of a recent retrospective pediatric study. Initiation of immunomodulator therapy at diagnosis did not alter the risk of surgery within 5 years of diagnosis.

Course and treatment of perianal disease in children newly diagnosed with Crohn's disease

BACKGROUND

We sought to characterize perianal disease and its treatment in pediatric patients newly diagnosed with Crohn's disease.

METHODS

Data were obtained from the Pediatric Inflammatory Bowel Disease (IBD) Collaborative Group Registry, a prospective, multicenter observational registry recording clinical and laboratory outcomes in children under 16 years of age newly diagnosed with IBD. Patients with Crohn's disease were selected who had data on perianal disease and at least 24 months of follow-up. The records of patients with a Pediatric Crohn's Disease Activity Index perianal subscore greater than 0 were reviewed, and patients with abscesses or fistulas were selected. The therapies used and the course of their perianal disease were then assessed.

RESULTS

Of the 276 patients identified, 41 had perianal lesions within 30 days of diagnosis. Thirteen of these had skin tags and fissures only, whereas 28 had fistulas and/or abscesses. The latter lesions resolved by 1 year in 20 patients, and 8 had chronic/recurrent perianal disease persisting for more than 1 year following diagnosis. Patients with fistulizing disease were much more likely to be treated and were treated earlier with antibiotics, infliximab, and immunomodulators than were nonfistulizing patients. Patients who developed chronic perianal disease were more likely to have low body mass indices and required more perianal surgery than did patients whose perianal disease resolved.

CONCLUSIONS

Approximately 10% of newly diagnosed pediatric patients with Crohn's disease will have perianal fistulas and/or abscesses at the time of diagnosis. Most of these will resolve within a year with medical therapy alone.

Altered bone mass in children at diagnosis of Crohn disease: a pilot study

OBJECTIVES

Recent studies have indicated that bone mineral density is reduced in children with inflammatory bowel disease. The exact cause of this reduction is unclear, but it is often attributed to corticosteroid use. This study examined the prevalence of reduced bone mass in otherwise healthy children newly diagnosed with Crohn disease without previous corticosteroid exposure.

METHODS

Eighteen steroid-naive children newly diagnosed with Crohn disease underwent dual energy x-ray absorptiometry. Disease activity, growth and pubertal development, nutritional assessment and bone mass measurements were recorded. z scores were adjusted for bone age.

RESULTS

Five of the 18 patients (28%) had a total bone mineral density z score less than -1 (one had a z score less than -2). Ten (56%) subjects had lumbar spine bone mineral density z scores less than -1 (two had z score less than -2). The subjects had significantly reduced mean lumbar spine bone mineral density z scores (P = 0.002). Delayed pubertal development correlated with whole body bone mineral density z scores (r = 0.64; P = 0.004). Most subjects were not meeting United States recommended dietary allowances for daily intake of calcium, vitamin D and total calories. The majority of subjects were not participating in weight-bearing physical activity.

CONCLUSION

Decreased bone mass is common in steroid naive children newly diagnosed with Crohn disease. Crohn disease appears to contribute to impaired bone mass independent of corticosteroid therapy.

Metabolic bone disease in inflammatory bowel disease

Osteoporosis is associated with a high morbidity rate and is a risk factor for fractures. Patients with inflammatory bowel disease are at increased risk of developing osteopenia and osteoporosis. Corticosteroid use, malnutrition, and proinflammatory cytokines are unique risk factors for bone loss in ulcerative colitis and Crohn disease. Bone mineral density is assessed by dual-energy X-ray absorptiometry and reported as a T score or number of standard deviations away from the mean. A T score < 1 SD below the mean is normal, 1 to 2.5 SD below the mean is consistent with osteopenia, and greater than 2.5 SD below the mean is defined as osteoporosis. Treatment includes a combination of basic preventative measures, for example, weight-bearing exercise, calcium, vitamin D, and pharmacologic agents, (e.g., bisphosphonates).

Treatment of Fistulizing Crohn's Disease in Children

Patients with Crohn's disease are at risk for developing both internal and external fistulae. These can be asymptomatic incidental radiologic findings or causes of incontinence, chronic pain, abscesses, and sepsis. They can have a devastating impact on quality of life. Careful prospective studies of therapy are few in adult medicine and entirely lacking in the pediatric age group. Assessment and management require a coordinated effort between gastroenterologist, radiologist, and surgeon. Principles of management include surgical drainage of infection combined with medical therapy. Only infliximab has been studied in prospective, double-blinded fashion and clearly shown to be of use in the short term. There is good evidence that metronidazole may be useful acutely and that 6-mercaptopurine azathioprine may help to maintain closure. Diverting ostomies are of very limited value and corticosteroids seem to make matters worse. There are many other therapies that have been reported to be helpful in small, uncontrolled studies.

Perspectives on osteoporosis in pediatric inflammatory bowel disease

Osteoporosis is now recognized as a problem in children with chronic illness. Decreased bone mineral density and increased risk of fracture have been reported in children with inflammatory bowel disease (IBD). Recent studies have led to a better understanding of the pathogenesis of bone loss. There are many risk factors for osteopenia and osteoporosis in children with IBD. Dual-energy x-ray absorptiometry remains the diagnostic procedure of choice for assessment of bone mineral density, but other modalities are being explored. Guidelines for diagnosis and treatment of osteoporosis in children have not been established. This article reviews the current understanding of osteopenia and osteoporosis in children with IBD.

Recognition and treatment of venous malformations of the rectum

Venous malformations of the rectum are uncommon lesions that present complex management problems (1-6). The vast majority of these lesions present with rectal bleeding in infancy or childhood. Many cases have been treated as colitis for years before the correct diagnosis was made. The correct diagnosis has generally been based on gross appearance, confirmed subsequently by plain radiographs and angiography. Heroic surgical intervention has been the only repeatedly reported "cure" in the literature. One patient has been reported who did well for 20 years with sclerosis of the hemorrhoidal vein at surgery followed by intermittent transrectal sclerotherapy (7,8). Another patient would appear to have had longterm success with radiation therapy (9-11). We report four new cases of venous malformations of the rectum and results to date of a new therapeutic option with transcutaneous ethanol sclerotherapy in two of these patients. A discussion of alternate methods of treatment is included.

Characterization of binding of simian rotavirus SA-11 to cultured epithelial cells

Rotavirus causes enteritis in both man and animals. The identity of the rotavirus receptor is not known. The nature of the binding interaction and the relationship between virus binding and internalization have not previously been reported. We studied the binding of [5,6-3H]uridine-labeled rotavirus SA11 to confluent monolayers of MA104 cells. We found approximately 13,000 receptor units per cell. The binding was sodium-dependent, pH-insensitive between 5.5 and 8, independent of added calcium, and dependent on sialic acid residues in the membrane. It could be inhibited by mucin. These features may provide clues to the identity of the receptor. Virus was not internalized to significant extent at 4 degrees C. After warming to 37 degrees C, virus was internalized over about 60 min. All binding sites appeared to be equally internalizable. The techniques developed to distinguish between binding and internalization may help to elucidate the mechanism of internalization.

Acidification of endosomes is not important for the entry of rotavirus into the cell

Rotavirus causes enteritis in both man and animals. The mechanism by which this protein-enveloped virus enters the cell to initiate infection is not known. Many viruses depend on the acidification of endosomes for entry into the cell. We studied the importance of the acidification of endosomes for the initiation of two early phases of rotavirus infection, virus RNA and peptide synthesis. Monensin, nigericin, chloroquine and ammonium chloride at a variety of concentrations caused no specific inhibition of virus RNA or peptide synthesis. We conclude that the acidification of endosomes is not important for the entry of rotavirus into the cell.

In vivo intestinal uptake of immunoreactive bovine albumin in piglet enteritis

We examined the uptake of bovine serum albumin (BSA) from the intestine into the circulation of 3-week-old piglets infected with transmissible gastroenteritis virus. Transfer of immunoreactive bovine serum albumin (iBSA) from the intestinal lumen into the circulation was enhanced during both the early invasive phase of this viral enteritis (12-h postinoculation) and the diarrheal phase (84-h postinoculation). In some animals, enhanced uptake persisted into the recovery phase, 324 h after inoculation. Gel filtration studies suggested that iBSA had the molecular size characteristic of native BSA; no immunoreactive fragments of BSA were detected. Based on studies of two animals, the half-life of iBSA approximated that of porcine albumin. Further study is required to determine the immunological consequences of the enhanced uptake of protein occurring during viral infection of the intestine.

D-Glucose transport in piglet jejunal brush-border membranes: insights from a disease model

We measured glucose transport in jejunal brush-border membrane vesicles isolated from piglets with acute viral diarrhea, comparing our results with those from control animals. Characterization of membranes from both study groups demonstrated comparable purity and integrity. In the presence of an inwardly directed Na SCN gradient, D-glucose accumulated in control vesicles to a concentration several times the 60-min equilibrium level. "Overshooting" uptake was much lower and more gradual in vesicles from 40-h transmissible gastroenteritis (TGE)-infected pigs compared with control pigs. Equilibrium kinetic studies, in which gramicidin was used to clamp membrane potential at zero, demonstrated a pattern of Na-dependent D-glucose transport in 40-h TGE-infected membranes that differed greatly from the control pattern. From an Eadie-Hofstee plot of stereospecific Na-dependent D-glucose uptake into control vesicles, a pattern suggesting two carrier populations emerged: one with a low-affinity, apparent Km equaling 52.63 +/- 13.81 mM and the other a high-affinity apparent Km equaling 3.92 +/- 0.24 mM for D-glucose. In 40-h TGE-infected membranes, the pattern conformed to a single line, suggesting a homogeneous population of low-affinity carriers, (Km = 37.03 +/- 1.92 mM), which did not differ from the low-affinity carriers seen in control animals. We conclude that the absence of the high-affinity D-glucose carriers in jejunal brush-border membrane is an important determinant of the defective glucose transport that characterizes viral diarrhea. Because previous studies have strongly suggested that in acute TGE diarrhea the epithelium is composed of relatively undifferentiated crypt-type cells, we speculate that high-affinity D-glucose carriers are lacking in normal crypt epithelial cells and that they are incorporated into brush-border membranes of jejunal enterocytes as the cells differentiate in the course of their migration from crypt to villus.

Altered jejunal permeability to macromolecules during viral enteritis in the piglet

We studied the macromolecular permeability of segments of jejunum from 2-wk-old piglets after the animals had been experimentally infected with an invasive enteric virus, transmissible gastroenteritis virus. Jejunal segments were mounted in Ussing chambers at stages of the infection, and permeability was measured using three probe molecules of differing molecular weights. In control tissue, permeability to horseradish peroxidase was 2.6 times higher across segments with Peyer's patches than across segments without Peyer's patches, whereas polyethylene glycol 4000 and mannitol permeabilities were the same in patch and nonpatch segments. Twelve hours after infection, when virus had invaded the mucosa causing a structural lesion, and before diarrhea had begun, horseradish peroxidase permeability increased in non-patch-containing segments to equal that across patch-containing tissue. At this early 12-h stage, polyethylene glycol 4000 and mannitol permeation were unchanged in patch-containing segments compared with controls. Ninety-six hours after transmissible gastroenteritis infection, when diarrhea was severe, horseradish peroxidase permeability in patch-free segments had returned to normal and patch-containing tissue permeability was diminished below control levels. Increased macromolecular permeability appears to occur only in the very early invasive stage of this viral enteritis and only in patch-free segments. Any consideration of the immunologic relevance of these complex phenomena must take into account the specialized function of the Peyer's patch regions of the small intestine.

Quantitative determination of macromolecular transport rate across intestinal Peyer's patches

We used horseradish peroxidase (HRP) (mol wt, 40,000) to compare in vitro, in Ussing chambers, the rates of protein transport across segments of piglet jejunum with and without Peyer's patches. The mean HRP transport rate across intestinal segments with a patch, 25.2 +/- 4.2 SE ng . min-1 . cm-2 (22 animals), was increased threefold (P less than 0.0005) compared with control (no patch) tissue, 7.9 +/- 1.0 ng . min-1 . cm-2 (n = 29). Neither rate showed saturation with increasing concentrations of HRP; both were inhibited 75-95% by a temperature drop from 37 to 15 degrees C. Transport across patch-containing tissue was inhibited 48 +/- 6% (n = 5, P less than 0.0025) by 1 mM NaF, but NaF had no consistent effect on the transport across tissue without Peyer's patches. We conclude that HRP transport is increased across Peyer's patches. This transport is dependent on metabolism and does not involve specific receptors. These findings support the concept that the Peyer's patch serves an antigen-sampling function in the gut.

Influence of pH on elastic deformability of the human erythrocyte membrane

Fresh human blood was diluted 1:5000 in buffered saline-sucrose solution and titrated to a pH varying from 4.5 to 10.5 with 0.1 N HCl or 0.1 N NaOH. Circular regions of the membrane of individual cells were then deformed at 25 degrees C by aspiration into a micropipette having an internal tip diameter of 0.9-1.4 micron. A membrane surface elasticity modulus, mu (dyn/cm), was computed from the relationship between length of the aspirated membrane and the deforming pressure according to a two-dimensional membrane model. Surface elasticity increases with decreasing pH and with time after the cell suspension is acidified, rising several orders of magnitude with a t1/2 of 1--5 h as pH is lowered from 7.2 to 4.6. This increase in mu is only partially reversible. pH greater than 7.2 had little effect on mu. Membrane surface elasticity is not affected by variations in external [Ca2+] over the range of 0--50 mM, tonicity of the suspension medium from 275--400 mosM, or age of 0--50 h. Addition of 50 mM NaHCO3 to the medium increases the rate of change of mu at a given pH. These results suggest that the elastic properties of the red cell membrane are largely determined by interactions among structural proteins located on the cytoplasmic surface of the membrane and that these interactions are initiated by changes in intracellular pH.

Is hexokinase present in the basal lateral membranes of rat kidney proximal tubular epithelial cells?

The possible presence of hexokinase in basal lateral membranes from rat kidney proximal tubules was investigated. Basal lateral membranes were obtained from homogenates of rat kidney cortex by differential centrifugation and free flow electrophoresis. They were further purified by density gradient centrifugation. Hexokinase activity was measured as the phosphorylation of D-[U14C]glucose. Throughout the purification of the membranes, the specific activity of hexokinase decreased while that of (Na+ + K+)-ATPase increased. Hexokinase activity in all fractions could be quantitatively accounted for in terms of cytosolic and mitochondrial enzyme contributions. It is concluded that there is no hexokinase activity in basal lateral membranes from rat kidney.