Cloning of ground-state intestinal stem cells from endoscopic biopsy samples

'Adult' or 'somatic' stem cells harbor an intrinsic ability to regenerate tissues. Heterogeneity of such stem cells along the gastrointestinal tract yields the known segmental specificity of this organ and may contribute to the pathology of certain enteric conditions. Here we detail technology for the generation of 'libraries' of clonogenic cells from 1-mm-diamter endoscopic biopsy samples from the human gastrointestinal tract. Each of the 150-300 independent clones in a typical stem cell library can be clonally expanded to billions of cells in a few weeks while maintaining genomic stability and the ability to undergo multipotent differentiation to the specific epithelia from which the sample originated. The key to this methodology is the intrinsic immortality of normal intestinal stem cells (ISCs) and culture systems that maintain them as highly immature, ground-state ISCs marked by a single-cell clonogenicity of 70% and a corresponding 250-fold proliferative advantage over spheroid technologies. Clonal approaches such as this enhance the resolution of molecular genetics, make genome editing easier, and may be useful in regenerative medicine, unravelling heterogeneity in disease, and facilitating drug discovery.

Unlimited expansion of intestinal stem cells from a wide range of ages

The recent technical advance in cloning and culturing ground-state intestinal stem cells (ISC) provides us an opportunity of accurate assessment of age-related impact on the function of highly proliferative intestinal stem cells. Our ability of indefinitely and robustly expanding single-stem-cell derived pedigrees in vitro allows us to study intestinal stem cells at the clonal level. Interestingly, comparable number of ISC clones was yielded from 1mm endoscopic biopsy of all donors despite the age. They were passaged in vitro as pedigrees and expanded to 1 billion cells in approximately sixty days without changes in stemness demonstrated by clonogenicity and multipotency. Therefore, our study shows that ISCs from a wide range of ages can be cloned and expanded to unlimited number in vitro with similar efficiency and stability. These patient-derived ISCs harbor intrinsic immortality and are ideal for autologous transplantation, supporting the promise of adult-stem-cell based personalized medicine.

Challenges in IBD Research: Precision Medicine

Precision medicine is part of five focus areas of the Challenges in IBD research document, which also includes preclinical human IBD mechanisms, environmental triggers, novel technologies, and pragmatic clinical research. The Challenges in IBD Research document provides a comprehensive overview of current gaps in inflammatory bowel diseases (IBD) research and delivers actionable approaches to address them. It is the result of a multidisciplinary input from scientists, clinicians, patients, and funders, and represents a valuable resource for patient centric research prioritization. In particular, the precision medicine section is focused on highlighting the main gap areas that must be addressed to get closer to treatments tailored to the biological and clinical characteristics of each patient, which is the aim of precision medicine. The main gaps were identified in: 1) understanding and predicting the natural history of IBD: disease susceptibility, activity, and behavior; 2) predicting disease course and treatment response; and 3) optimizing current and developing new molecular technologies. Suggested approaches to bridge these gaps include prospective longitudinal cohort studies to identify and validate precision biomarkers for prognostication of disease course, and prediction and monitoring of treatment response. To achieve this, harmonization across studies is key as well as development of standardized methods and infrastructure. The implementation of state-of-the-art molecular technologies, systems biology and machine learning approaches for multi-omics and clinical data integration and analysis will be also fundamental. Finally, randomized biomarker-stratified trials will be critical to evaluate the clinical utility of validated signatures and biomarkers in improving patient outcomes and cost-effective care.

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.

Inflammatory Bowel Disease: Effects on Bone and Mechanisms

Inflammatory bowel disease (IBD) is associated with decreased bone mass and alterations in bone geometry from the time of diagnosis, before anti-inflammatory therapy is instituted. Deficits in bone mass can persist despite absence of symptoms of active IBD. The effects of IBD on the skeleton are complex. Protein-calorie malnutrition, inactivity, hypogonadism, deficits in calcium intake and vitamin D consumption and synthesis, stunted growth in children, decreased skeletal muscle mass, and inflammation all likely play a role. Preliminary studies suggest that the dysbiotic intestinal microbial flora present in IBD may also affect bone at a distance. Several mechanisms are possible. T cells activated by the gut microbiota may serve as "inflammatory shuttles" between the intestine and bone. Microbe-associated molecular patterns leaked into the circulation in IBD may activate immune responses in the bone marrow by immune cells and by osteocytes, osteoblasts, and osteoclasts that lead to decreased bone formation and increased resorption. Finally, intestinal microbial metabolites such as H₂S may also affect bone cell function. Uncovering these mechanisms will enable the design of microbial cocktails to help restore bone mass in patients with IBD.

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.

Programmed cell death-1, PD-1, is dysregulated in T cells from children with new onset type 1 diabetes

BACKGROUND

Programmed death cell 1 (PD-1) is an inhibitor of T cell activation and is also functionally linked to glycolysis. We hypothesized that PD-1 expression is defective in activated T cells from children with type 1 diabetes (T1D), resulting in abnormal T cell glucose metabolism.

METHODS

In this pilot study, we enrolled children with new onset T1D within 2 weeks of diagnosis (T1D), unaffected siblings of T1D (SIBS), unaffected, unrelated children (CTRL), children with new onset, and untreated Crohn disease (CD). We repeated the assays 4-6 months post-diagnosis in T1D (T1D follow up). We analyzed anti-CD3/-CD28-stimulated peripheral blood mononuclear cells (PBMC) subsets for PD-1 expression by flow cytometry at baseline and after 24 h in culture. We measured cytokines in the culture medium by multiplex ELISA and glycolytic capacity with a flux analyzer.

RESULTS

We enrolled 37 children. T cells derived from subjects with T1D had decreased PD-1 expression compared to the other study groups. However, in T1D follow-up T cells expressed PD-1 similarly to controls, but had no differences in PBMC cytokine production. Nonetheless, T1D follow up PBMCs had enhanced glycolytic capacity compared to T1D.

CONCLUSIONS

Activated T cells from T1D fail to upregulate PD-1 upon T-cell receptor stimulation, which may contribute to the pathogenesis of T1D. T1D follow up PBMC expression of PD-1 normalizes, together with a significant increase in glycolysis compared to T1D. Thus, insulin therapy in T1D children is associated with normal PD1 expression and heightened glycolytic capacity in PBMC.

Prediction of complicated disease course for children newly diagnosed with Crohn's disease: a multicentre inception cohort study

BACKGROUND

Stricturing and penetrating complications account for substantial morbidity and health-care costs in paediatric and adult onset Crohn's disease. Validated models to predict risk for complications are not available, and the effect of treatment on risk is unknown.

METHODS

We did a prospective inception cohort study of paediatric patients with newly diagnosed Crohn's disease at 28 sites in the USA and Canada. Genotypes, antimicrobial serologies, ileal gene expression, and ileal, rectal, and faecal microbiota were assessed. A competing-risk model for disease complications was derived and validated in independent groups. Propensity-score matching tested the effect of anti-tumour necrosis factor α (TNFα) therapy exposure within 90 days of diagnosis on complication risk.

FINDINGS

Between Nov 1, 2008, and June 30, 2012, we enrolled 913 patients, 78 (9%) of whom experienced Crohn's disease complications. The validated competing-risk model included age, race, disease location, and antimicrobial serologies and provided a sensitivity of 66% (95% CI 51-82) and specificity of 63% (55-71), with a negative predictive value of 95% (94-97). Patients who received early anti-TNFα therapy were less likely to have penetrating complications (hazard ratio [HR] 0·30, 95% CI 0·10-0·89; p=0·0296) but not stricturing complication (1·13, 0·51-2·51; 0·76) than were those who did not receive early anti-TNFα therapy. Ruminococcus was implicated in stricturing complications and Veillonella in penetrating complications. Ileal genes controlling extracellular matrix production were upregulated at diagnosis, and this gene signature was associated with stricturing in the risk model (HR 1·70, 95% CI 1·12-2·57; p=0·0120). When this gene signature was included, the model's specificity improved to 71%.

INTERPRETATION

Our findings support the usefulness of risk stratification of paediatric patients with Crohn's disease at diagnosis, and selection of anti-TNFα therapy.

FUNDING

Crohn's and Colitis Foundation of America, Cincinnati Children's Hospital Research Foundation Digestive Health Center.

Cloning and variation of ground state intestinal stem cells

Stem cells of the gastrointestinal tract, pancreas, liver, and other columnar epithelia collectively resist cloning in their elemental states. Here we demonstrate the cloning and propagation of highly clonogenic, “ground state” stem cells of the human intestine and colon. We show that derived stem cell pedigrees sustain limited copy number and sequence variation despite extensive serial passaging and display exquisitely precise, cell-autonomous commitment to epithelial differentiation consistent with their origins along the intestinal tract. This developmentally patterned and epigenetically maintained commitment of stem cells likely enforces the functional specificity of the adult intestinal tract. Using clonally-derived colonic epithelia, we show that toxins A or B of the enteric pathogen C. difficile recapitulate the salient features of pseudomembranous colitis. The stability of the epigenetic commitment programs of these stem cells, coupled with their unlimited replicative expansion and maintained clonogenicity, suggests certain advantages for their use in disease modeling and regenerative medicine.

Effects of exclusive enteral nutrition on bone mass, linear growth and body composition in children with Crohn's disease

Inflammatory bowel disease, especially Crohn's disease, is linked to significant growth stunting, sarcopenia (loss of skeletal muscle mass), deterioration of bone architecture and reduction in bone mass. Exclusive enteral nutrition (EEN) has been shown to correct nutritional deficiencies, provide adequate calories for growth, and alleviate intestinal inflammation in Crohn's disease with a favorable adverse effect profile. In this chapter, we report a summary of the effects of EEN on linear growth, skeletal health and lean body mass in children with Crohn's disease.

Bone health in children and adolescents with chronic diseases that may affect the skeleton: the 2013 ISCD Pediatric Official Positions

The aim of this Task Force was to review the use of dual-energy X-ray absorptiometry (DXA) in children and adolescents with underlying chronic diseases that pose risk factors for compromised bone health, such as inflammation, glucocorticoid therapy, or decreased mobility. The Task Force systematically analyzed more than 270 studies, with an emphasis on those published in the interval since the original 2007 Position Statements. Important developments over this period included prospective cohort studies demonstrating that DXA measures of areal bone mineral density (aBMD) predicted incident fractures and the development of robust reference data and strategies to adjust for bone size in children with growth impairment. In this report, we summarize the current literature on the relationship between DXA-based aBMD and both fracture (vertebral and non-vertebral) outcomes and non-fracture risk factors (e.g., disease characteristics, ambulatory status, and glucocorticoid exposure) in children with chronic illnesses. Most publications described the aBMD profile of children with underlying diseases, as well as the cross-sectional or longitudinal relationship between aBMD and clinically relevant non-fracture outcomes. Studies that addressed the relationship between aBMD and prevalent or incident fractures in children with chronic illnesses are now emerging. In view of these updated data, this report provides guidelines for the use of DXA-based aBMD in this setting. The initial recommendation that DXA is part of a comprehensive skeletal healthy assessment in patients with increased risk of fracture is unchanged. Although the prior guidelines recommended DXA assessment in children with chronic diseases at the time of clinical presentation with ongoing monitoring, this revised Position Statement focuses on the performance of DXA when the patient may benefit from interventions to decrease their elevated risk of a clinically significant fracture and when the DXA results will influence that management.

The role of microbial byproducts in protection against immunological disorders and the hygiene hypothesis

Over the past three decades the incidence of allergic disorders and autoimmune diseases has risen and this trend is particularly prominent in developed nations. The hygiene hypothesis suggests that as a living environment becomes more sanitized, children are not exposed to microbial and parasitic stimulations that were once commonly acquired since early in life, leading to a lack of immune sensitization tending towards T helper 2 (Th2) dominance. This postulation is sufficient to explain allergic disorders, which mostly result from hyper Th2 responses, but inadequate to explain the increase in Th1 or Th17-based autoimmunity. Recent advances in experimental mouse models revealed that stimulation of Toll-like receptors (TLRs) by pathogen-associated molecular patterns could reduce symptoms of allergic airway disease and prevent the onset of autoimmunity. The underlying mechanism for the protective effects of TLR ligands is currently under intense investigation and there are indications that IL-10-producing B cells, regulatory T cells, and innate immune cells play an important role during this process. The finding that early exposure to microbial byproducts contributes to the modulation of immunological disorders may once again modify our interpretation of the hygiene hypothesis.

Fecal osteoprotegerin may guide the introduction of second-line therapy in hospitalized children with ulcerative colitis

BACKGROUND

Osteoprotegerin (OPG) is increased in inflamed colonic mucosa and has a role in immune regulation and apoptosis resistance. Fecal OPG may be useful in predicting corticosteroid resistance in hospitalized children with severe ulcerative colitis (UC). We aimed to determine whether fecal OPG predicts the need for second-line therapies in children hospitalized for UC.

METHODS

We included 83 children with UC admitted for intravenous corticosteroid treatment. Children were classified as responders/nonresponders based on the need for therapy escalation. Fecal OPG results were compared with those of four other fecal markers.

RESULTS

Of the enrolled children, seven had day 1 samples only, 53 children had day 3 samples only, and 23 had both. Twenty-two children failed corticosteroid therapy and required infliximab (n = 20) or colectomy (n = 2). On the third treatment day the median fecal OPG levels were significantly higher in the nonresponders group compared with the responders: 77 pmol/L (interquartile range [IQR] 27-137) versus 13 pmol/L (3-109); P = 0.007. The best day 3 fecal OPG cutoff to predict second-line therapy was >50 pmol/L with a sensitivity of 71% and specificity of 69% (area under the receiver operator curve [ROC] of 0.70%-95% confidence interval [CI] 0.57-0.82). Fecal OPG was superior to day 3 fecal calprotectin, lactoferrin, and S100A12 as a predictor of corticosteroid nonresponse, but equivalent to the less commonly used M2-pyruvate kinase.

CONCLUSIONS

Day 3 fecal OPG may guide the decision to institute second-line therapy in children with severe UC. The role of OPG in the inflammatory response in pediatric UC deserves further study.

Effect of gluten-free diet on growth and glycemic control in children with type 1 diabetes and asymptomatic celiac disease

We aimed to evaluate the effects of a gluten-free diet on growth and glycemic control in children with type 1 diabetes mellitus (DM) and asymptomatic, biopsy-proven celiac disease (CD). Each case of CD was compared to two children with DM and no CD. We studied weight, height, and hemoglobin A1c (HgbAlc) up to 12 months pre- and post- CD diagnosis in 29 cases and 58 controls. The change in body mass index (deltaBMI Z-score) over 2 years was significantly higher in CD cases vs. controls (mean +/- SD 0.33 +/- 0.74 vs. +/- 0.08 +/- 0.46; p = 0.023). However, BMI Z-score did not change in CD patients diagnosed with DM for > 1 year. Mean HgbA1c was similar between groups throughout the study. In conclusion, children with asymptomatic CD and DM do not have significant changes in BMI, height Z-score or metabolic control 1 year post-diagnosis.

Proinflammatory fecal mRNA and childhood bacterial enteric infections

INTRODUCTION: Assessment of specific mRNAs in human samples is useful in characterizing disease. However, mRNA in human stool has been understudied. RESULTS: Compared to controls, infected stools showed increased transcripts of IL-1β, IL-8 and calprotectin. mRNA and protein concentrations correlated for IL-8, but not for calprotectin. DISCUSSION: Stool mRNA quantification offers a potentially useful, noninvasive way to assess inflammation in the gastrointestinal tract, and may be more sensitive than EIA. METHODS: We purified fecal RNA from 46 children infected with Campylobacter jejuni, Escherichia coli O157:H7, Salmonella spp. or Shigella sonnei and 26 controls and compared the proportions of IL-1β, IL-8, osteoprotegerin and calprotectin mRNA between groups using qRT-PCR. We determined the concentrations of calprotectin, IL-8 and osteoprotegerin by enzyme immunoassays in cognate specimens.

A two-year longitudinal study of persistent lean tissue deficits in children with Crohn's disease

BACKGROUND & AIMS

Deficits in lean body mass have been reported in cross-sectional studies of children with Crohn's disease, but no longitudinal data exist from diagnosis. We observed the effects of Crohn's disease on body composition and bone mineral content (BMC), beginning at diagnosis and followed prospectively for 2 years.

METHODS

The study was conducted at 2 tertiary care centers for pediatric inflammatory bowel diseases. At diagnosis we recorded age, weight, height, levels of serum interleukin-6 and insulin-like growth factor-1, sexual maturation stage, disease activity, z scores for body mass index (BMI), fat-free mass (FFM), and bone mineral content (BMC). z Scores were adjusted for height and age, when appropriate. Measurements were made yearly in patients with Crohn's disease (n = 42) but only at the start of the study in controls (n = 81).

RESULTS

BMI and FFM z scores were significantly reduced at the time of diagnosis in children with Crohn's disease, compared with controls. During the 2-year study period, the BMI z scores normalized in patients with Crohn's disease, but the FFM z scores did not increase significantly. The BMC z scores increased significantly, but they were still lower than control values after 2 years. Changes in BMC during a period of 2 years were associated with increases in FFM (R(2) = 0.318, P < .01).

CONCLUSIONS

The correction of BMI that is associated with clinical improvement in children with Crohn's disease 2 years after diagnosis results from gains in fat mass. Significant FFM deficits might hamper normal acquisition of bone mass in children with Crohn's disease because of a lack of mechanical strain.

Chronic pediatric inflammatory diseases: effects on bone

In children, chronic inflammatory diseases present a significant challenge to long-term skeletal health. These conditions are often associated with poor appetite and suboptimal overall nutrition, altered nutrient utilization, delayed puberty, inactivity, and reduced muscle mass, all of which can alter bone metabolism. In addition, bone cell activity is susceptible to the effects of the immune response that characterizes these diseases. Moreover, drugs used to treat these maladies, notably glucocorticoids, may have negative effects on bone formation and on linear growth in developing children. As a result, predicted peak bone mass may not be achieved, and fracture risk may be increased in the short term or in the future. Studies using primarily dual energy X-ray absorptiometry have documented that deficits in bone mass are common in these diseases. However, there are wide variations in the prevalence of low bone mass, largely due to differences in the characteristics of each study population. Recent studies provide insight into the pathogenesis of decreased bone mass in these conditions. In this paper we will provide an overview of the effects of chronic inflammatory conditions on bone mass in children. We will also present relevant data from adult patients, when pediatric data are scant or not available.

Natural history of bone metabolism and bone mineral density in children with inflammatory bowel disease

BACKGROUND

In children with inflammatory bowel disease (IBD) it is not known whether reductions in bone mineral density (BMD) are a consequence of bone turnover alterations and if BMD improves with treatment.

METHODS

In a cohort of children with IBD, we prospectively measured indicators of bone remodeling, body mass index (BMI), disease activity, intact parathyroid hormone, serum IL-6, and insulin-like growth factor-I at diagnosis and then every 6 months for 2 years. BMD was determined annually using dual x-ray absorptiometry (DXA). BMD Z-scores were calculated using height/age. Baseline measurements and calcium intake were compared with a group of age- and sex-matched healthy children.

RESULTS

We observed that at diagnosis total body BMD Z-score (mean +/- SD) was -0.78 +/- 1.02 for Crohn's disease (CD, n = 58), -0.46 +/- 1.14 for ulcerative colitis (UC, n = 18), and -0.17 +/- 0.95 for control (CL, n = 49) (P < 0.01, CD versus CL). In CD, a BMD Z-score <-1.0 was associated with lower BMI and higher serum IL-6. Patients with CD and UC had low bone turnover. Activation of bone formation paralleled clinical improvement, but BMC gain was less than expected over the 2-year study period, especially in CD. Prednisone use did not correlate with low BMD.

CONCLUSIONS

Decreased bone turnover occurs in children newly diagnosed with IBD. Although indicators of osteoblast activity increase with clinical improvement, bone mineral accrual does not accelerate. Children with low BMI may be considered for BMD screening, since they are at risk for low bone mass.

Are activated T cells regulators of bone metabolism in children with Crohn disease?

OBJECTIVES

To test the hypothesis that circulating activated T cells may release cytokines that decrease bone turnover in children with Crohn disease.

STUDY DESIGN

Newly diagnosed Crohn disease and healthy controls of similar age were compared for bone age, bone mineral content and density, markers of bone remodeling, and serum concentration and in vitro T-cell production of receptor activator of nuclear factor kappaB ligand (RANKL), interferon (INF)-gamma, and osteoprotegerin (OPG).

RESULTS

Newly diagnosed children with Crohn disease (n=23) had similar bone mineral density (BMD) z-scores and body mass index as the controls (n=40). Biochemical markers of bone remodeling indicated a state of low bone turnover in the Crohn disease patients compared with controls. Serum OPG (pmol/L; mean+/-SD, median) was higher (4.24+/-1.74, 3.98 vs 3.38+/-0.83, 3.41; P<.05), and serum RANKL (pmol/L) was lower in the Crohn disease patients (0.50+/-0.86, 0.28 vs 1.02+/-1.63, 0.49; P<.01), consistent with decreased bone resorption. Activated T cells from Crohn disease patients produced a higher concentration of INF-gamma (ng/microg protein) than those from controls (20.03+/-26.39, 8.70 vs 9.76+/-14.10, 6.17; P<.05).

CONCLUSIONS

The newly diagnosed children with Crohn disease exhibited reduced bone remodeling, possibly due to T-cell INF-gamma and OPG.

IBD and skeletal health: children are not small adults!

Patients with inflammatory bowel disease often have decreased bone mass, and fragility fractures can occur. Multiple disease- and treatment related factors, including malnutrition, inflammation, malabsorption, decreased weight-bearing physical activity, and corticosteroids negatively influence bone metabolic activity. Because low-impact fracture is the pathologic expression of critically reduced bone mass and bone quality, knowing the relative risk of fractures in patients with IBD is of great interest. The absolute risk for incident fractures in these patients is still being debated. Clinical and laboratory research is clarifying mechanisms by which IBD can affect the function of osteoblasts and osteoclasts. In this concise review, we aim to provide an update on this topic, with focus on how pediatric IBD affects bone health.

Effects of activated T cells on osteoclastogenesis depend on how they are activated

INTRODUCTION

Activated T cells are emerging as important regulators of osteoclast function in inflammatory diseases. Both pro- and anti-resorptive properties have been described. We reasoned that this reported variability of the effects of T cells on osteoclast formation depends on how T cells are activated in vitro.

METHODS

We harvested T lymphocytes from 5-week-old C57BL/6 mouse spleens. Activation was performed with anti-CD3epsilon and -CD28 Ab (Abs), concanavalin A (Con A), phytohemagglutinin (PHA), or the superantigen Staphylococcal enterotoxin A (SEA). Osteoclastogenesis was induced by receptor activator of NF-kappaB ligand (RANKL) in the mouse macrophage cell line RAW 264.7 cells, or primary macrophage CD11b+ cells from mouse spleen. Cells were cultured with T cells or with their conditioned medium.

RESULTS

Co-culture of activated T lymphocytes with RAW 264.7 cells inhibited osteoclastogenesis but only when activated by Abs. This effect was CD4+ -dependent. Conditioned medium from activated T lymphocytes with Abs consistently blocked osteoclastogenesis in RAW 264.7 and CD11b+ cells. T cells activated with SEA, Con A, and PHA had inconsistent effects on osteoclastogenesis. We then tested the role of interferon (IFN)-gamma, a known inhibitor of osteoclastogenesis, in the effects of T cells on osteoclast formation. IFN-gamma neutralizing antibody blocked the inhibitory effect of T-cell conditioned medium on osteoclastogenesis. Osteoclast precursors from IFN-gamma receptor-null mice treated with 0.1% medium from activated T cells formed osteoclasts. However, higher doses of medium inhibited osteoclastogenesis, so that we cannot exclude that other factors besides IFN-gamma may be involved.

CONCLUSIONS

Available methods to activate T lymphocytes result in variable effects on osteoclastogenesis. IFN-gamma is the main factor responsible for the inhibitory effects of activated T cells on osteoclast formation.

Effects of serum from children with newly diagnosed Crohn disease on primary cultures of rat osteoblasts

OBJECTIVES

We propose that Crohn disease (CD) decreases bone formation via circulating inflammatory mediators. We therefore examined the effects of serum from newly diagnosed, untreated children with CD on osteoblasts in culture and the role of interleukin-6 (IL-6), a cytokine present in excess in active CD that also has direct effects on bone.

METHODS

Bone mineral density was measured by dual x-ray absorptiometry. Primary cultures of rat osteoblasts were treated with serum from patients with CD and healthy controls. We measured expression of osteoblast proliferation, viability, differentiation markers, and mineralized nodule formation. Neutralizing antibodies were used to inhibit the effects of IL-6 present in serum.

RESULTS

We studied 24 children with CD (14 male) and 31 controls (15 male). Spine bone mineral density was lower in patients with CD (Z score, -0.8 +/- 0.9 vs. 0.0 +/- 1.0 for controls; P < 0.05). Nodule formation was markedly decreased in osteoblasts treated with CD serum. However, CD serum did not affect osteoblast proliferation or viability. Expression of proteins characteristic of mature osteoblasts-osteocalcin and alkaline phosphatase-was reduced. Unlike our results in a model of intact bone, neutralization of IL-6 did not inhibit the effects of CD serum. Addition of IL-6 to control serum to match serum concentrations in CD had no effect either.

CONCLUSIONS

CD serum affects osteoblast function and probably differentiation in vitro, suggesting a mechanism by which CD may affect bone formation. IL-6 by itself is not sufficient to cause these effects and probably needs a cofactor present in intact bone.

Effect of Crohn's disease on bone metabolism in vitro: a role for interleukin-6

Circulating proinflammatory cytokines may be involved in osteopenia associated with Crohn's disease (CD). Therefore, the effect of interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF) a contained in Crohn's serum on bone formation was examined in a bone organ culture system. Initially, serum levels of IL-6, IL-1beta, and TNF-a were determined by ELISA in newly diagnosed, untreated children with CD and healthy age-matched controls. Serum IL-6 levels were significantly higher in patients with CD than in controls (23.9 +/- 2.8 pg/ml vs. 0.7 pg/ml +/- 0.2; p < 0.001), whereas IL-1beta and TNF-alpha serum levels were not. In the organ culture studies, 20-day-old fetal rat parietal bones were incubated for 96 h with CD or control serum, serum preincubated with a neutralizing antibody to each cytokine or a nonimmune immunoglobulin control, and with IL-6. Bone formation measured by assaying calcium content and dry weight was significantly decreased in bones exposed to Crohn's serum. Light microscopy of the bones treated with CD serum revealed a discontinuous, uneven mineralized bone matrix and disorganized osteoblasts with altered morphology. Incubation with an antibody that neutralized IL-6 activity prevented the change in osteoblast and bone morphology. TNF-a and IL-1beta antibodies had no apparent effects. Collagen synthesis and DNA content were not affected by CD serum. Also, addition of IL-6 to the culture medium decreased mineralization. These results suggest that IL-6 is a mediator of the effects of Crohn's serum on in vitro mineralization and may be a contributing factor to the osteopenia associated with CD.

High-salt diet impairs hypoxia-induced cAMP production and hyperpolarization in rat skeletal muscle arteries

This study determined the effects of hypoxia on diameter, vascular smooth muscle (VSM) transmembrane potential (E(m)), and vascular cAMP levels for in vitro cannulated skeletal muscle resistance arteries (gracilis arteries) from Sprague-Dawley rats fed a low-salt (LS) or a high-salt (HS) diet. Arterial diameter and VSM E(m) were measured in response to hypoxia, iloprost, cholera toxin, forskolin, and aprikalim. In HS rats, arterial dilation and VSM hyperpolarization after hypoxia, iloprost, and cholera toxin were impaired versus responses in LS rats, whereas responses to forskolin and aprikalim were unaltered. Blockade of prostaglandin H(2) and thromboxane A(2) receptors had no effect on responses to hypoxia or iloprost in vessels from both rat groups, suggesting that inappropriate activation of these receptors does not contribute to the impaired hypoxic dilation with HS. Hypoxia, cholera toxin, and iloprost increased vascular cAMP levels in vessels of LS rats only, whereas forskolin increased cAMP levels in all vessels. These data suggest that reduced hypoxic dilation of skeletal muscle microvessels in rats on a HS diet may reflect an impaired ability of VSM to produce cAMP after exposure to prostacyclin.

Longitudinal differences in vascular control mechanisms in isolated resistance arteries of the rat cremaster muscle

The purpose of this study was to determine if there are intrinsic differences in resting tone, vascular reactivity, myogenic responses, and neurogenic vasoconstriction between the large and small feeder arteries and first order arterioles (1A) of the rat cremaster muscle. The pudic-epigastric artery (PEA), external spermatic artery (ESA), and 1A were isolated and changes in vessel diameter were recorded in response to: (1) increases in intralumenal pressure, (2) inhibition of nitric oxide synthase (NOS), (3) norepinephrine (NE), (4) acetylcholine (ACh), and (5) perivascular nerve stimulation. Vessel responses to Ca(2+)-free physiological salt solution were measured to assess resting tone, which was significantly greater in the ESA and 1A compared to the PEA. NE caused a significant constriction of all vessels, with 1A exhibiting the greatest sensitivity. NOS inhibition did not alter vascular sensitivity to NE, but enhanced resting tone in ESA and 1A. ACh induced significant dilation in ESA and 1A, with minimal effect on PEA. The myogenic response was not different between ESA and 1A, but was minimal in PEA. Perivascular nerve stimulation induced a significant vasoconstriction in all vessels tested. These results suggest that the relative importance of different vascular control mechanisms varies substantially at different levels of the cremasteric arterial network and that the ESA and 1A may be the major site of active vascular regulation upstream from the cremaster muscle microcirculation.

Contribution of extrinsic factors and intrinsic vascular alterations to reduced arteriolar reactivity with high-salt diet and hypertension

OBJECTIVE

To determine whether the impaired relaxation of skeletal muscle arterioles of rats on high-salt diet or with reduced renal mass hypertension (RRM-HT) represents intrinsic alterations to microvessels alone, or whether extravascular influences also contribute to reduced dilator responses.

METHODS

Normotensive (NT) Sprague-Dawley rats were fed low-salt (LS) or high-salt (HS) diets, and RRM-HT rats were fed HS diet for 4-6 weeks. In situ and isolated cremaster muscle first-order arterioles (1A) were examined using television microscopy, and a video micrometer was used to measure diameter changes in response to acetylcholine (ACH), cholera toxin (CT), and sodium nitroprusside (SNP).

RESULTS

Compared to normotensive low-salt (NT-LS) rats, responses of 1A to the agonists were reduced in normotensive high-salt (NT-HS) and RRM-HT rats. Arteriolar reactivity to the agonists in NT-LS rats aid in NT-HS rats was not different between in situ and in vitro environments. However, in RRM-HT rats, the reactivity of 1A to each agonist was greater in isolated arterioles than in in situ arterioles.

CONCLUSIONS

These results suggest that the impaired response of skeletal muscle arterioles to vasodilator stimuli in normotensive rats on high-salt diet primarily reflects alterations to microvessels alone, while reduced dilator responses in RRM-HT rats represent a combination of extravascular influences and intrinsic alterations to arterioles themselves.

Dyspepsia in children and adolescents: a prospective study

BACKGROUND

Dyspepsia is poorly characterized in the pediatric population. The goal of the current study was to describe the clinical constellation and natural history of dyspepsia in children and adolescents seen in a pediatric gastroenterology practice.

METHODS

A standardized questionnaire was administered by a pediatric gastroenterologist to all subjects 5 or more years of age (and their parents or guardians) treated in a referral pediatric gastroenterology practice for 1 month or more of abdominal pain or discomfort, nausea, or vomiting. Subjects with dyspepsia and dyspepsia subtypes (ulcer-like, dysmotility-like) were identified by using previously defined adult criteria. Evaluation and treatment were performed at the discretion of the attending pediatric gastroenterologist.

RESULTS

During a 1-year period, 257 patients were screened with 127 subjects fulfilling criteria for dyspepsia (59% girls, 85% white; median age, 11.7 years; median duration of symptoms, 8 months). Symptoms were ulcer-like in 26% and dysmotility-like (nausea predominance) in 15% of subjects. In those with dyspepsia, irritable bowel syndrome and gastroesophageal reflux were noted in 24% and 43%, respectively. Esophagogastroduodenoscopy and biopsy were performed in 56 subjects with 21 (38%) having mucosal inflammation (Helicobacter pylori in 5). The remaining 35 subjects (62%) were considered to have functional dyspepsia. Duration of symptoms less than 1 year and vomiting were risk factors for mucosal inflammation. Follow-up at 6 months to 2 years revealed 70% of subjects were either asymptomatic or much improved regardless of the cause of dyspepsia.

CONCLUSION

Most children and adolescents with dyspepsia do not have serious disease. In our referral population H. pylori infection was unusual, and no peptic ulceration was found. Most subjects with functional dyspepsia have improvement of symptoms over time.

Cable-piliated Burkholderia cepacia binds to cytokeratin 13 of epithelial cells

Although the Burkholderia cepacia complex consists of several genomovars, one highly transmissible strain of B. cepacia has been isolated from the sputa of cystic fibrosis (CF) patients throughout the United Kingdom and Canada. This strain expresses surface cable (Cbl) pili and is thought to be the major strain associated with the fatal "cepacia syndrome." In the present report we characterize the specific 55-kDa buccal epithelial cell (BEC) protein that binds cable pilus-positive B. cepacia. N-terminal sequences of CNBr-generated internal peptides identified the protein as cytokeratin 13 (CK13). Western blots of BEC extracts probed with a specific monoclonal antibody to CK13 confirmed the identification. Mixed epidermal cytokeratins (which contain CK13), cytokeratin extract from BEC (which consists essentially of CK13 and CK4), and a polyclonal antibody to mixed cytokeratins inhibited B. cepacia binding to CK13 blots and to normal human bronchial epithelial (NHBE) cells. Preabsorption of the antikeratin antibody with the BEC cytokeratin fraction reversed the inhibitory effect of the antibody. A cytokeratin mixture lacking CK13 was ineffective as an inhibitor of binding. Colocalization of CK13 and B. cepacia by confocal microscopy demonstrated that intact nonpermeabilized NHBE cells express small amounts of surface CK13 and bind Cbl-positive B. cepacia in the same location. Binding to intact NHBE cells was dependent on bacterial concentration and was saturable, whereas a Cbl-negative isolate exhibited negligible binding. These findings raise the possibility that surface-accessible CK13 in respiratory epithelia may be a biologically relevant target for the binding of cable piliated B. cepacia.

Bone abnormalities in gastrointestinal and hepatic disease

Bone is a dynamic tissue that undergoes constant remodeling in response to local and environmental stimuli. Bone mass is maintained by this delicate equilibrium between bone formation and bone resorption. In growing children, the balance is tilted toward bone formation until peak bone mass is achieved in the second decade of life. Alterations in bone metabolism can result in decreased bone mass (osteopenia and osteoporosis) or impaired mineralization of the bone protein matrix (rickets and osteomalacia). Diseases of the alimentary tract such as celiac disease, inflammatory bowel diseases, gastrectomy, cholestatic liver diseases, liver transplantation, and hepatitis C can affect bone mineralization, remodeling, or bone mass. This article presents a summary of recent reports concerning bone disorders associated with disorders of the liver and gastrointestinal tract.

Management of fibrosing pancreatitis in children presenting with obstructive jaundice

BACKGROUND

Children with fibrosing pancreatitis are conventionally treated surgically to relieve common bile duct (CBD) obstruction caused by pancreatic compression. Residual pancreatic function has not been formally tested in these patients.

AIMS

To evaluate the usefulness of non-surgical temporary drainage in children with fibrosing pancreatitis and to assess pancreatic function after resolution of their CBD obstruction.

PATIENTS

Four children (1.5-13 years; three girls).

METHODS AND RESULTS

Abdominal sonography and computed tomography revealed diffuse enlargement of the pancreas, predominantly the head. The CBD was dilated due to compression by the head of the pancreas. Pancreatic biopsy specimens obtained in three patients showed notable acinar cell atrophy and extensive fibrosis. Cystic fibrosis was excluded. No other cause of pancreatitis was identified. Pancreatic tissue from one patient contained viral DNA sequences for parvovirus B19 detected by polymerase chain reaction; serum IgM to parvovirus was positive. Three patients had temporary drainage of the CBD and one patient underwent a choledochojejunostomy. Serial imaging studies revealed resolution of the CBD obstruction with reduction in pancreatic size. Exocrine pancreatic function deteriorated. Three patients developed pancreatic insufficiency within two to four months of presentation. The fourth patient has notably diminished pancreatic function, but remains pancreatic sufficient. None has diabetes mellitus.

CONCLUSIONS

Temporary drainage of the CBD obstruction is recommended in fibrosing pancreatitis in children along with close monitoring of the clinical course, before considering surgery.

Adherence to lipids and intestinal mucin by a recently recognized human pathogen, Campylobacter upsaliensis

Campylobacter upsaliensis is a recently recognized human enteric pathogen associated with enteritis, colitis, bacteremia, and sepsis. Very little is known about the mechanisms of pathogenesis of this organism. The goals of this study were to determine whether C. upsaliensis binds to epithelial cells and whether there are specific lipid molecules that might serve as cell membrane receptors. In addition, we also explored C. upsaliensis binding to purified human small-intestinal mucin, since the mucus gel overlying the epithelium provides an initial contact surface for the bacteria and must be penetrated for the organisms to reach their cell receptors. Binding of C. upsaliensis to model epithelial cells was shown by microscopy adhesion assays, and binding to lipids was detected by thin-layer chromatography-overlay assays. Bacteria bound to phosphatidylethanolamine (PE), gangliotetraosylceramide (Gg4), and, more weakly, to phosphatidylserine (PS). There was no binding to ceramide, cholesterol, phosphatidylcholine, and globosides. Using receptor-based microtiter well immunoassays, we observed binding to be equal, specific, and saturable for PE and Gg 4 but low and nonspecific for PS. At least five bacterial surface proteins (50 to 90 kDa) capable of PE binding were identified by a lipid-silica affinity column technique. In slot blot overlay assays, biotin-labeled C. upsaliensis also bound in a concentration-dependent fashion to purified human small-intestinal mucin, implying that these microorganisms also express an adhesin(s) recognizing a specific mucin epitope(s). We speculate that binding to mucins may influence access of the bacteria to cell membrane receptors and thereby influence host resistance to infection.

Burkholderia (basonym Pseudomonas) cepacia binding to lipid receptors

Piliated Burkholderia (formerly Pseudomonas) cepacia from sputa of cys tic fibrosis patients in Toronto, Canada, were shown earlier to bind to purified mucins and to a protein receptor on epithelial cells via a 22-kDa adhesin located on unique cable pili. However, a second receptor, thought to be lipid in nature, was also identified on cells and appeared to serve as the major cell receptor for poorly piliated or nonpiliated isolates. In the present study in vitro approaches were used to identify putative lipid receptors for B. cepacia and to explore the nature of the binding interaction. As judged by thin-layer chromatography overlay assays, the best receptors were digalactosylceramide and globotriosylceramide (Gb(3)). Both contain and unsubstituted terminal Gal alpha 1-4Gal sequence. B cepacia also bound moderately to galactosylceramide, gangliotriosylceramide, and gangliotetraosylceramide. Binding to glycolipids was not affected by tetramethylurea, a hydrophobic-bond-breaking adhesin for GB(3). Binding to glycolipids was not affected by tetramethylurea, a hydrophobic-bond-breaking agent. Binding was influenced by the structure of the ceramide, which probably affects the presentation of the agent. Binding was influenced by the structure of the ceramide, which probably affects the presentation of the carbohydrate epitope to the bacteria. Gb(3) was also the major receptor in lipid extracts of human erythrocytes, human buccal epithelial cells and HEp-2 laryngeal epithelial cells. In a receptor-based enzyme-linked immunosorbent assay, binding to Gb(3) within a phospholipid-cholesterol mixture (a membrane-like environment) increased and then approached saturation as a direct function of increasing bacterial concentration. The calculated value of K(a) (3.06 X 10(-8) ml/CFU), the affinity constant, was almost identical to the K(a) calculated earlier for B. cepacia binding to a set of lipid receptors in buccal epithelial cells (1.5 X 10(-8) to 2.0 X 10(-8) ml/CFU). Our findings suggest that within cell membranes, galactose-containing glycolipids, particularly Gb(3) are good candidates for receptors for B. cepacia, particularly for isolates in which cable pili are poorly expressed.