Howard A. Kader

Normal Thiopurine Methyltransferase Levels Do Not Eliminate 6-mercaptopurine or Azathioprine Toxicity in Children with Inflammatory Bowel Disease

6-mercaptopurine (6-MP) and azathioprine (AZA) are used to treat inflammatory bowel disease (IBD). Side effects include infection, leukopenia, hepatitis, and pancreatitis. The level of thiopurine methyltransferase (TPMT), which metabolizes 6-MP to 6-methylmercaptopurine, may reflect the risk of side effects. We sought to evaluate the relationship between the side effects of these medications and the TPMT level of pediatric patients with IBD. The medical records of our patients who were diagnosed with IBD and who received 6-MP or AZA were reviewed for measured TPMT levels. All red blood cell (RBC) TPMT levels were determined at the Mayo Medical Laboratories, Rochester, MN. The occurrence of leukopenia, elevated aminotransferases, and pancreatitis was evaluated. Twenty-two patients, mean age 13.7 years, received 6-MP or AZA and had TPMT levels measured. The TPMT levels ranged 10.7-27.5 U/mL RBC with a mean of 17.2 +/- 3.2 U/mL RBC. Two children had levels below the accepted norm of 13.8 U/mL RBC. One of these patients (50%) developed both elevation of aminotransferases and leukopenia. Of all, 20 children had normal levels, 3 (15.0%) exhibited side effects: hepatitis (n = 2) and leukopenia (n = 1). We conclude that side effects of 6-MP or AZA occur despite normal TPMT levels.

Variation in care in pediatric Crohn disease.

Objectives:Variation in medical care can be a barrier to improving clinical outcomes. We aim to describe the variation in care of Crohn disease as provided by a broad sample of pediatric gastroenterologists. Methods:Two hundred forty-six Crohn disease patients of 93 pediatric gastroenterologists from 48 practice sites starting treatment with either thiopurine or infliximab were studied. We assessed variation in diagnostic testing that had been performed to establish the diagnosis of Crohn disease and to assess the phenotype, extent, and severity of disease. We also assessed variation in initial thiopurine and infliximab dosage and in nutritional therapy. Results:Diagnostic studies in which care was uniform included complete blood count, performed in 100% of patients, erythrocyte sedimentation rate and colonoscopy in 96%, and upper endoscopy in 89%. However, imaging of the small bowel had not been performed in 19%, and a stool test for pathogens had not been performed in 29%. Thiopurine methyltransferase (TPMT) had been measured in 61% of patients before treatment with a thiopurine; in 85%, TPMT was normal. Nonetheless, even when TPMT was normal, 40% of patients received an initial dose of thiopurine that was lower than recommended. Testing for tuberculosis before initiating treatment with infliximab was not performed in 30%. In addition, 36% of severely underweight patients were not receiving a multivitamin supplement, supplemental formula, or tube feeding. Conclusions:There is variation in diagnostic and therapeutic interventions in the management of pediatric Crohn disease, and gaps exist between recommended and actual care.

Single toxin detection is inadequate to diagnose Clostridium difficile diarrhea in pediatric patients

BACKGROUND & AIMS Clostridium difficile is an important cause of symptomatic diarrhea in pediatric patients. The bacterium produces two toxins, although many laboratories assay for only one. We questioned this diagnostic approach when patients had positive results for C. difficile at our institution, but initially had tested negative at outside laboratories. METHODS We retrospectively analyzed relative frequencies of C. difficile toxin A alone, toxin B alone, and toxins A and B from pediatric patients with diarrhea. Results were stratified according to toxin detection and patient age. RESULTS Of 1061 specimens, 276 (26.8%) were positive for C. difficile toxin(s). Fifty-one (18.5%) were positive for toxin A alone, 133 (48.2%) for toxin B alone, and 92 (33.3%) for both toxins. Assaying for toxin B identified C. difficile infection more frequently than did assaying for toxin A (P < 0.0001). The frequency of toxin B detection was significantly higher for older children but not for infants. CONCLUSIONS Testing for C. difficile toxin A or toxin B alone will result in more frequent misdiagnosis than testing for both toxins. This practice may lead to inappropriate further invasive investigations in children, although this finding may not be applicable to adults.

Diagnosis and Treatment of Perianal Crohn Disease: NASPGHAN Clinical Report and Consensus Statement

Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract that includes both Crohn disease (CD) and ulcerative colitis. Abdominal pain, rectal bleeding, diarrhea, and weight loss characterize both CD and ulcerative colitis. The incidence of IBD in the United States is 70 to 150 cases per 100,000 individuals and, as with other autoimmune diseases, is on the rise. CD can affect any part of the gastrointestinal tract from the mouth to the anus and frequently will include perianal disease. The first description connecting regional enteritis with perianal disease was by Bissell et al in 1934, and since that time perianal disease has become a recognized entity and an important consideration in the diagnosis and treatment of CD. Perianal Crohn disease (PCD) is defined as inflammation at or near the anus, including tags, fissures, fistulae, abscesses, or stenosis. The symptoms of PCD include pain, itching, bleeding, purulent discharge, and incontinence of stool. In this report, we review and discuss the etiology, diagnosis, evaluation, and treatment of PCD.

Mucosal-Associated Invariant T Cells in the Human Gastric Mucosa and Blood: Role in Helicobacter pylori Infection

Mucosal-associated invariant T (MAIT) cells represent a class of antimicrobial innate-like T cells that have been characterized in human blood, liver, lungs, and intestine. Here, we investigated, for the first time, the presence of MAIT cells in the stomach of children, adults, and the elderly undergoing routine endoscopy and assessed their reactivity to Helicobacter pylori (H. pylori – Hp), a major gastric pathogen. We observed that MAIT cells are present in the lamina propria compartment of the stomach and display a similar memory phenotype to blood MAIT cells. We then demonstrated that gastric and blood MAIT cells are able to recognize H. pylori. We found that CD8+ and CD4−CD8− (double negative) MAIT cell subsets respond to H. pylori-infected macrophages stimulation in a MR-1 restrictive manner by producing cytokines (IFN-γ, TNF-α, IL-17A) and exhibiting cytotoxic activity. Interestingly, we observed that blood MAIT cell frequency in Hp+ve individuals was significantly lower than in Hp−ve individuals. However, gastric MAIT cell frequency was not significantly different between Hp+ve and Hp−ve individuals, demonstrating a dichotomy between blood and gastric tissues. Further, we observed that the majority of gastric MAIT cells (>80%) expressed tissue-resident markers (CD69+ CD103+), which were only marginally present on PBMC MAIT cells (<3%), suggesting that gastric MAIT cells are readily available to respond quickly to pathogens. These results contribute important new information to the understanding of MAIT cells function on peripheral and mucosal tissues and its possible implications in the host response to H. pylori.

Introduction of 6-mercaptopurine in Crohn's disease patients during the perioperative period: a preliminary evaluation of recurrence of disease.

BACKGROUND Recurrence of Crohns disease after surgery is a common occurrence, pointing to the need for a strategy to prevent recurrent disease. We report the postoperative course of 10 patients who required intestinal resections for complications related to Crohns disease. METHODS All patients had a Pediatric Crohns Disease Activity Index score of 10 or greater. Among these patients, 5 began treatment with 6-mercaptopurine in the perioperative period. All 10 had received various combinations of prednisone and salicylate compounds. Patients who were given 6-mercaptopurine did not discontinue the medication until 2 years after the surgery. RESULTS To date, none of the five patients who were placed on 6-mercaptopurine have had recurrence of their Crohns disease (mean disease-free period 32.6 +/- 18.4 months). Among those five patients not receiving 6-mercaptopurine there have been three relapses (mean time to relapse 3.7 +/- 1.2 months). Log-rank sum analyses of Kaplan-Meier survival curves show benefit to patients receiving 6-mercaptopurine in preventing relapses after intestinal resection (p < 0.05). CONCLUSIONS Although the underlying pathophysiologic reasons leading to the high relapse rate after intestinal surgery in Crohns disease are unknown, we conclude that treatment with 6-mercaptopurine in the perioperative period may be warranted to help prevent the recurrence of Crohns disease after surgery.

Contribution of higher risk genes and European admixture to Crohn's disease in African Americans

Background: African Americans (AAs) are an admixed population of West African (WA) and European ancestry (EA). Crohns disease (CD) susceptibility genes have not been established. We therefore evaluated the contribution of European admixture and major established risk genes to AA CD. Methods: Ninety‐seven admixture informative markers were genotyped for ancestry estimates using STRUCTURE. Overall, 354 AA CD cases and 354 ethnicity‐matched controls were genotyped for total 21 single nucleotide polymorphisms (SNPs) in ATG16L1, NOD2, IBD5, IL23R and IRGM by TaqMan or direct sequencing. Association was evaluated by logistic regression, adjusted for ancestry. Results: Mean EA was similar among the CD cases and controls (20.9% and 20.4%, respectively, P = 0.58). No significant admixture differences were observed among 211 to 227 cases stratified by phenotypic subclassifications including onset, surgery, site, and behavior. CD was associated with NOD2 carrier (6.93% CD, 2.15% Controls, P = 0.007), ATG16L1 Thr300Ala (36.1% CD, 29.3% Controls, P = 0.003), SLC22A4 and SLC22A5 (IBD5 locus) functional SNPs (Leu503Phe [10.5% CD, 7.6% Controls, P = 0.05] and g‐207c [41.3% CD, 35.7% Controls, P = 0.03], respectively), and IL23R rs2201841 (18.2% CD, 13.8% Controls, P = 0.03), but not IRGM variants, nor three African ancestral NOD2 nonsynonymous variants. IBD5 risk was recessive. An all‐minor allele IBD5 haplotype from EA was associated (P = 0.05), whereas a more common haplotype isolating g‐207c was not. Conclusions: Specific functional gene variations contribute significantly to AA CD risk. Established NOD2, SLC22A4‐A5, and ATG16L1 variants show increased CD risk, with IBD5 recessive. Although CD is more common in whites, European admixture is similar among AA cases and controls. (Inflamm Bowel Dis 2012;)

Characterization and Functional Properties of Gastric Tissue-Resident Memory T Cells from Children, Adults, and the Elderly

T cells are the main orchestrators of protective immunity in the stomach; however, limited information on the presence and function of the gastric T subsets is available mainly due to the difficulty in recovering high numbers of viable cells from human gastric biopsies. To overcome this shortcoming we optimized a cell isolation method that yielded high numbers of viable lamina propria mononuclear cells (LPMC) from gastric biopsies. Classic memory T subsets were identified in gastric LPMC and compared to peripheral blood mononuclear cells (PBMC) obtained from children, adults, and the elderly using an optimized 14 color flow cytometry panel. A dominant effector memory T (TEM) phenotype was observed in gastric LPMC CD4+ and CD8+ T cells in all age groups. We then evaluated whether these cells represented a population of gastric tissue-resident memory T (TRM) cells by assessing expression of CD103 and CD69. The vast majority of gastric LPMC CD8+ T cells either co-expressed CD103/CD69 (>70%) or expressed CD103 alone (~20%). Gastric LPMC CD4+ T cells also either co-expressed CD103/CD69 (>35%) or expressed at least one of these markers. Thus, gastric LPMC CD8+ and CD4+ T cells had the characteristics of TRM cells. Gastric CD8+ and CD4+ TRM cells produced multiple cytokines (IFN-γ, IL-2, TNF-α, IL-17A, MIP-1β) and up-regulated CD107a upon stimulation. However, marked differences were observed in their cytokine and multi-cytokine profiles when compared to their PBMC TEM counterparts. Furthermore, gastric CD8+ TRM and CD4+ TRM cells demonstrated differences in the frequency, susceptibility to activation, and cytokine/multi-cytokine production profiles among the age groups. Most notably, children’s gastric TRM cells responded differently to stimuli than gastric TRM cells from adults or the elderly. In conclusion, we demonstrate the presence of gastric TRM, which exhibit diverse functional characteristics in children, adults, and the elderly.

The utility of Ultrasound site selection for pediatric percutaneous liver biopsy

Background The site for percutaneous liver biopsy is determined by physical examination and anatomic landmarks. The authors compared physical examination with ultrasound examination to determine liver location, size, and an optimal biopsy site. Methods A pediatric gastroenterology fellow or attending gastroenterologist initially selected a biopsy site by physical examination. An ultrasonographer performed a limited ultrasound examination to evaluate this site. Results Sixty biopsy sites from 58 patients were evaluated. Forty-six patients had no previous liver surgery. Two patients had had a Kasai procedure. Ten patients had had orthotopic liver transplantation. The mean age of the patients was 11.1 ± 7.6 years. Ultrasonography detected the following potential complications of percutaneous biopsy at the site determined by physical examination: insufficient liver (7 of 15, 47.0%), diaphragm injury (4 of 15, 27.0%), bowel perforation (2 of 15, 13.0%), kidney laceration (1 of 15, 7.0%), and large blood vessel laceration (1 of 15, 7.0%). These ultrasound findings directed a change in biopsy site for 15 (25.0%) physical examination sites. Major biopsy complications were rare (1.7%). Conclusion Ultrasound examination resulted in a location change to a more optimal site in 25.0% of the sites determined by physical examination. Ultrasound determination of the biopsy site should be considered before pediatric percutaneous liver biopsy.

Genetic Risk for Inflammatory Bowel Disease Is a Determinant of Crohn's Disease Development in Chronic Granulomatous Disease.

Background:Approximately, one-third to one-half of children with chronic granulomatous disease (CGD) develop gastrointestinal inflammation characteristic of idiopathic inflammatory bowel disease (IBD), usually Crohns disease. We hypothesized that the overall IBD genetic risk, determined by IBD genetic risk score (GRS), might in part determine IBD development in CGD. Methods:We reviewed medical records to establish IBD diagnoses in CGD subjects seen at NIAID. IBD risk single nucleotide polymorphism genotypes were determined using the Immunochip, and GRS were estimated by Mangrove. Results:Among 157 white patients with CGD, 55 were confirmed, 78 excluded, and 24 were uncertain for IBD. Two hundred one established, independent European IBD risk single nucleotide polymorphisms passed quality control. After sample quality control and removing non-IBD CGD patients with perianal disease, mean GRS for 40 unrelated patients with CGD-IBD was higher than 53 CGD non-IBD patients (in log2-scale 0.08 ± 1.62 versus −0.67 ± 1.64, P = 0.026) but lower than 239 IBD Genetics Consortium (IBDGC) young-onset Crohns disease cases (0.76 ± 1.60, P = 0.025). GRS for non-IBD CGD was similar to 609 IBDGC controls (−0.69 ± 1.60, P = 0.95). Seven established IBD single nucleotide polymorphisms were nominally significant among CGD-IBD versus CGD non-IBD, including those near LACC1 (P = 0.005), CXCL14 (P = 0.007), and TNFSF15 (P = 0.016). Conclusions:The weight of the common IBD risk alleles are significant determinants of IBD in CGD. However, IBD risk gene burden among CGD children with IBD is significantly lower than that in nonsyndromic pediatric Crohns disease, congruent with the concept that defective superoxide production in CGD is also a major IBD risk factor. Individual IBD genes might interact with the CGD defect to cause IBD in CGD.