Elevation of serum interleukin-6 but not serum-soluble interleukin-2 receptor in children with Crohn's disease

Inflammation, but Not the Underlying Disease or Its Location, Predicts Oral Iron Absorption Capacity in Patients With Inflammatory Bowel Disease

BACKGROUND AND AIMS

Anaemia is common in patients with inflammatory bowel disease [IBD], its two main aetiologies being iron deficiency anaemia [IDA] and anaemia of chronic inflammation [ACI]. Impaired intestinal iron absorption due to inflammatory cytokines is thought to play a role in ACI. We undertook for the first time a controlled prospective study investigating effects of differing underlying diseases, disease locations, and types of iron deficiency or anaemia on oral iron absorption in adult IBD patients with and without inflammation.

METHODS

This study was a comparative, single-centred open clinical trial in adults with IBD [n = 73] and healthy controls [n = 22]. Baseline parameters included blood count, iron status [ferritin, transferrin, transferrin saturation, soluble transferrin receptor, hepcidin, serum iron], high-sensitivity C-reactive protein [hsCRP] and interleukin-6. Iron absorption was tested using one oral, enteric-coated capsule containing 567.7 mg iron[II]-glycine-sulphate complex. Serum iron was determined 60/90/120/180/240 min after ingestion.

RESULTS

Iron absorption capacity was shown to be influenced by inflammation and anaemia or iron deficiency [ID] type but not by underlying disease type or localisation. The ACI group showed a significantly lower iron absorption capacity than all others. Whereas hsCRP levels [-0.387, p < 0.001], IL-6 [-0.331, p = 0.006], ferritin [-0.531, p < 0.001], and serum hepcidin [-0.353, p = 0.003] correlated negatively with serum iron change at 2 h, transferrin showed a positive correlation at the same time point [0.379, p < 0.001].

CONCLUSIONS

Underlying disease type and localisation appear to have little effect on iron absorption capacity, whereas lack of response to oral iron correlates well with serum markers of inflammation. Iron absorption capacity is thus significantly reduced in the presence of inflammation.

Application of Proteomics to Inflammatory Bowel Disease Research: Current Status and Future Perspectives

Inflammatory bowel disease (IBD) is a chronic relapsing/remitting inflammatory illness of the gastrointestinal tract of unknown aetiology. Despite recent advances in decoding the pathophysiology of IBD, many questions regarding disease pathogenesis remain. Genome-wide association studies (GWAS) and knockout mouse models have significantly advanced our understanding of genetic susceptibility loci and inflammatory pathways involved in IBD pathogenesis. Despite their important contribution to a better delineation of the disease process in IBD, these genetic findings have had little clinical impact to date. This is because the presence of a given gene mutation does not automatically correspond to changes in its expression or final metabolic or structural effect(s). Furthermore, the existence of these gene susceptibility loci in the normal population suggests other driving prerequisites for the disease manifestation. Proteins can be considered the main functional units as almost all intracellular physiological functions as well as intercellular interactions are dependent on them. Proteomics provides methods for the large-scale study of the proteins encoded by the genome of an organism or a cell, to directly investigate the proteins and pathways involved. Understanding the proteome composition and alterations yields insights into IBD pathogenesis as well as identifying potential biomarkers of disease activity, mucosal healing, and cancer progression. This review describes the state of the art in the field with respect to the study of IBD and the potential for translation from biomarker discovery to clinical application.

Body height in paediatric inflammatory bowel diseases: A structural equation model analysis

BACKGROUND

Linear growth restriction is a unique feature of paediatric inflammatory bowel diseases (IBD), and reduced insulin-like growth factor (IGF-1) is a major determinant of short stature. We aimed to assess factors influencing somatic height in children suffering from IBD.

MATERIALS AND METHODS

This was a retrospective, cross-sectional study conducted after approval by Institutional authorities. Anthropometric data, disease-related factors, biochemical and clinical indices of inflammation and endocrine parameters were recorded and considered as explanatory covariates. A structural equation model analysis was utilized. Somatic height was the outcome of interest, and possible associations of explanatory covariates directly or through the mediation effect of IGF-1 were assessed.

RESULTS

Systemic inflammation, as expressed by high-sensitivity intereukin-6 (IL-6), and nutritional status described by body mass index (BMI) were the pathways that significantly affected stature through the mediation effect of IGF-1. Cortisol showed a direct, positive and independent of IGF-1 association with height.

CONCLUSIONS

Insulin-like growth factor-1 is a key player in the process that results in impaired linear growth. Malnutrition and systemic inflammation have a restrictive action on growth by reducing circulating IGF-1. The positive relation of serum cortisol to height could correspond to suppressed pituitary-adrenal axis due to long-term use of glucocorticoids.

Circulating Angiogenesis Regulators in Cancer Patients

Background/Aims

To date, numerous studies have demonstrated that several angiogenesis regulators circulate in the blood and may function as endocrine factors in cancer patients. This review aims to give a comprehensive insight into the possible clinical value of circulating angiogenesis regulators, mainly basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF), angiogenin, pleiotrophin, thrombospondin (TSP) and endostatin (ES) in cancer patients.

Methods

A computerized (MEDLINE) and a manual search based on the reference lists of the publications were performed to identify articles published on this topic.

Results

In a detailed literature search, approximately 100 publications were found up to the end of 1999. Circulating angiogenic factors such as bFGF, VEGF, HGF and angiogenin have been evaluated not only as diagnostic and/or prognostic factors but also as predictive factors in cancer patients. On the other hand, little is known about the clinical significance of negative regulators. Neither the source nor the mechanism of protein externalization has been clarified in detail.

Conclusions

Although there are no known factors with established clinical utility, circulating angiogenesis regulators may be useful in several situations. They could be used to determine the risk of developing cancer, to screen for early detection, to distinguish benign from malignant disease, and to distinguish between different types of malignancies. In patients with established malignancies such factors might be used to determine prognosis, to predict the response to therapy, and to monitor the clinical course. Further investigations are warranted to assess the specific utility of each factor.

Electroacupuncture Attenuates Visceral Hypersensitivity by Inhibiting JAK2/STAT3 Signaling Pathway in the Descending Pain Modulation System

Electroacupuncture (EA) has been used for treating visceral hypersensitivity (VH). However, the underlying molecular mechanism remains unclear. This study was aim to testify the effect of EA on ileitis-provoked VH, and to confirm whether EA attenuates VH through Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3) signaling pathway in the periaqueductal gray (PAG)-the rostral ventromedial medulla (RVM)-the spinal cord dorsal horn (SCDH) axis.

Methods: Goats were anesthetized and laparotomized for injecting 2,4,6-trinitro-benzene-sulfonic acid (TNBS)-ethanol solution (30mg TNBS dissolved in 40% ethanol) into the ileal wall to induce VH. EA was treated for 30min from day 7, then every 3 days for six times. VH was assessed by visceromotor response (VMR) and pain behavior response to 20, 40, 60, 80, and 100 mmHg colorectal distension pressures at day 7, 10, 13, 16, 19, and 22. The spinal cord in the eleventh thoracic vertebra and the brain were collected at day 22. The protein and mRNA levels of IL-6, JAK2, and STAT3 in the SCDH were detected with western blot and qPCR, respectively. The distribution of these substances was observed with immunohistochemistry in the ventrolateral PAG (vlPAG), RVM (mainly the nucleus raphe magnus, NRM), SCDH, the nucleus tractus solitaries (NTS) and the dorsal motor nucleus of vagi (DMV).

Results: Goats administered with TNBS-ethanol solution showed diarrhea, enhanced VMR and pain behavior response, and increased IL-6, phosphorylated JAK2 and STAT3 (pJAK2 and pSTAT3) in the vlPAG, NRM, NTS and DMV, and their protein and mRNA levels in the SCDH. EA relieved diarrhea, VMR and pain behavior response, decreased IL-6, pJAK2 and pSTAT3 levels in the vlPAG, NRM, SCDH, NTS, and DMV except for pSTAT3 in the DMV, but did not affect mRNA level of these three substances in the SCDH.

Conclusion: EA attenuates VH probably through inhibiting JAK2/STAT3 signaling pathway in the PAG-RVM-SCDH axis.

Clinical Utility of Biomarkers in IBD

There is no gold standard for the diagnosis and monitoring of inflammatory bowel diseases (IBD). Biomarkers are useful tools for the management of patients suffering from IBD. However, they should be used only when their additional information is useful for clinical decision-making. In principal, four situations during the management of an individual IBD patient can be discriminated from a clinical standpoint in which biomarkers provide useful information. First, biomarkers may be helpful when the diagnosis of IBD is established and aid in the discrimination between ulcerative colitis (UC) and Crohn's disease (CD) is necessary. Second, biomarkers may be helpful in the prognostic evaluation of IBD severity or disease behavior and for early decisions on the best treatment. The third situation in which biomarkers are useful is the evaluation of disease activity during the disease course, for monitoring and for guidance of ongoing treatment. Finally, the fourth typical situation when biomarkers are of value is after surgery to predict or diagnose a relapse of the disease. From a clinical point of view, it may be more useful to discuss specific biomarkers and their individual value and impact in these four prototypic situations than to sum up advantages and disadvantages for each biomarker isolated from the clinical situation. Therefore, this overview is structured in chapters reflecting those four typical situations during the disease course of IBD patents to critically evaluate the potential and value of each of the biomarkers in the specific situation.

Relationship of clinical symptoms with biomarkers of inflammation in pediatric inflammatory bowel disease

In adult inflammatory bowel disease (IBD) patients, there is a strong discrepancy between symptoms and biomarkers of inflammation. Data on pediatric IBD patients are conflicting. Therefore, we aimed to investigate the relationship between clinical symptoms and biomarkers of inflammation in pediatric IBD. Patients aged <18 years with previously diagnosed Crohn's disease (CD) or ulcerative colitis (UC) were included. Clinical disease activity was determined using the abbreviated Pediatric CD Activity Index (aPCDAI) or Pediatric UC Activity Index (PUCAI). Biochemical disease activity was assessed using fecal calprotectin (FC) and C-reactive protein (CRP). In total, 127 patients (62 male; median age 14.9 years) were included (82 CD, 45 UC). FC correlated weakly with total aPCDAI score (r s = 0.32; 95 % CI 0.12-0.51; p = 0.003) and total PUCAI score (r s = 0.36; 95 % CI 0.07-0.62; p = 0.015). Only aPCDAI components abdominal examination and perirectal disease and PUCAI component activity level had a significant correlation with levels of FC. CRP correlated weakly with total aPCDAI score (r s = 0.28; 95 % CI 0.05-0.46; p = 0.012) and aPCDAI components abdominal examination and activity level. No significant correlation was observed between CRP and total PUCAI score (r s = 0.01; 95 % CI -0.34-0.29; p = 0.961) or individual PUCAI components.

CONCLUSION

There is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.

WHAT IS KNOWN

• A substantial proportion of asymptomatic pediatric inflammatory bowel disease (IBD) patients have elevated biomarkers of inflammation. • There is a strong discrepancy between symptoms and biomarkers of inflammation in adults with IBD. What is New: • Clinical symptoms are only weakly associated with levels of fecal calprotectin and serum C-reactive protein in children and adolescents with previously diagnosed IBD. • Similarly to adult IBD patients, there is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.

Characterization of Serum Cytokine Profile in Predominantly Colonic Inflammatory Bowel Disease to Delineate Ulcerative and Crohn's Colitides

BACKGROUND

As accessible diagnostic approaches fail to differentiate between ulcerative colitis (UC) and Crohn’s colitis (CC) in one-third of patients with predominantly colonic inflammatory bowel disease (IBD), leading to inappropriate therapy, we aim to investigate the serum cytokine levels in these patients in search of molecular biometric markers delineating UC from CC.

METHODS

We measured 38 cytokines, chemokines, and growth factors using magnetic-bead-based multiplex immunoassay in 25 UC patients, 28 CC patients, and 30 controls. Our results are compared with those from a review of current literature regarding advances in serum cytokine profiles and associated challenges preventing their use for diagnostic/prognostic purposes.

RESULTS

Univariate analysis showed statistically significant increases of eotaxin, GRO, and TNF-α in UC patients compared to controls (Ctrl); interferon γ, interleukin (IL)-6, and IL-7 in CC group compared to Ctrl; and IL-8 in both UC and CC versus Ctrl. No cytokines were found to be different between UC and CC. A generalized linear model identified combinations of cytokines, allowing the identification of UC and CC patients, with area under the curve (AUC) = 0.936, as determined with receiver operating characteristic (ROC) analysis.

CONCLUSIONS

The current knowledge available about circulating cytokines in IBD is often contradictory. The development of an evidence-based tool using cytokines for diagnostic accuracy is still preliminary.

Serum protein profiling of adults and children with Crohn disease

OBJECTIVES

Crohn disease (CD) and ulcerative colitis (UC), known collectively as inflammatory bowel diseases (IBDs), are chronic immunoinflammatory pathologies of unknown aetiology. Despite the frequent use of biomarkers in medical practice, there is a relative lack of information regarding validated paediatric biomarkers for IBD. Furthermore, biomarkers proved to be efficacious in adults are frequently extrapolated to the paediatric clinical setting without considering that the pathogenesis of many diseases is distinctly different in children. In the present study, proteomics technology was used to monitor differences in protein expression among adult and young patients with CD, identify a panel of candidate protein biomarkers that may be used to improve prognostic-diagnostic accuracy, and advance paediatric medical care.

METHODS

Male and female serum samples from 12 adults and 12 children with active CD were subjected to 2-dimensional gel electrophoresis. Following the relative quantitation of protein spots exhibiting a differential expression between the 2 groups by densitometry, the spots were further characterized by matrix-assisted laser desorption tandem time-of-flight mass spectrometer. The results were confirmed by Western blot analysis.

RESULTS

Clusterin was found to be significantly overexpressed in adults with CD, whereas ceruloplasmin and apolipoprotein B-100 were found to be significantly overexpressed in children, indicating that the expression of these proteins may be implicated in the onset or progression of CD in these 2 subgroups of patients.

CONCLUSIONS

Interestingly, we found a differential expression of several proteins in adults versus paediatric patients with CD. Undoubtedly, future experiments using a larger cohort of patients with CD are needed to evaluate the relevance of our preliminary findings.

Herpes simplex virus-1 infection of colonic explants as a model of viral-induced activation of Crohn's disease

The exogenous triggers responsible for Crohn's disease (CD) relapses are not often identified. Cytomegalovirus and other members of the herpesvirus family have been implicated in precipitating relapses. However, the role of viral infections in the immunopathogenesis of CD remains poorly understood. We describe an ex-vivo model of primary viral infection of CD tissue with Herpes Simplex Virus type I (HSV-1). IL-6 and CD68 served as markers for CD inflammation, type I IFNs for viral infection. Colonic explants obtained from CD resections were infected via the luminal or the submucosal compartments with HSV-1 or mock virus solution, at varying concentrations for up to 20 h. Serial tissue sections were assayed for expression of HSV-1 specific antigens, CD-68, IL-6 and DC-SIGN. Culture supernatants were tested for IL-6 and type I IFN production. Positive immunostaining for HSV-1 specific antigens was consistently detectable using 11×10(6)PFU from 13 h onwards, mainly on cells located in the submucosa, and in the perivascular area. CD68 was up-regulated in lamina propria macrophages from mildly and non-inflamed CD tissue after HSV-1 infection. IL-6+ cells in the infected tissues were mainly submucosal DC-SIGN+ dendritic cells. IL-6 and IFN-β levels were higher in the supernatants from HSV-1-infected explants compared to controls after 20 h of culture (p<0.01). These data show increased expression of inflammatory markers during the initial stages of HSV-1 primary infection using CD colonic explants. This in vitro model appears promising to study the immunoregulatory changes induced by microbial infection in reactivation of CD.

The role of growth hormone and insulin-like growth factor-1 in Crohn's disease: implications for therapeutic use of human growth hormone in pediatric patients

PURPOSE OF REVIEW

This review evaluates the role of the growth hormone (GH) and insulin-like growth factor (IGF) in influencing linear growth in pediatric Crohn's disease. It also examines the current evidence concerning the use of recombinant human growth hormone (rhGH) as a potential therapy in achieving optimal growth and inducing mucosal healing for pediatric Crohn's disease.

RECENT FINDINGS

Current treatment strategies for Crohn's disease including antitumor necrosis factor-α (TNF-α) therapy have been demonstrated to improve growth velocity, but linear growth deficits persist despite optimization of therapy. By complex mechanisms, including the reduction of levels of IGF-1 and induction of systemic and hepatic GH resistance, cytokines such as TNF-α and interleukin-6 (IL-6), commonly elevated in active Crohn's disease, are important as mediators of linear growth delay. Recent evidence suggests that rhGH therapy is effective in improving short-term linear growth for a selected group of patients but of limited benefit as a therapy for improving mucosal disease and reducing clinical disease activity.

SUMMARY

Crohn's disease interacts with the GH-IGF-1 axis in important ways. Recent studies evaluating rhGH use in pediatric Crohn's disease have demonstrated some efficacy in reversing persistent linear growth delay but limited benefits in terms of improving mucosal disease and clinical disease activity. Larger studies of adequate power are needed to confirm a true benefit in terms of growth, to examine a potential benefit with regard to modification of disease activity, and to evaluate long-term risks.

Mechanisms of growth impairment in pediatric Crohn's disease

Crohn's disease manifests during childhood or adolescence in up to 25% of patients. The potential for linear growth impairment as a complication of chronic intestinal inflammation is unique to pediatric patient populations. Insulin-like growth factor I (IGF-I), produced by the liver in response to growth hormone (GH) stimulation, is the key mediator of GH effects at the growth plate of bones. An association between impaired growth in children with Crohn's disease and low IGF-I levels is well recognized. Early studies emphasized the role of malnutrition in suppression of IGF-I production. However, a simple nutritional hypothesis fails to explain all the observations related to growth in children with Crohn's disease. The direct, growth-inhibitory effects of proinflammatory cytokines are increasingly recognized and explored. The potential role of noncytokine factors, such as lipopolysaccharides, and their potential to negatively influence the growth axis have recently been investigated with intriguing results. There is now reason for optimism that the modern anticytokine therapeutic agents available for treating children and adolescents with Crohn's disease will reduce the prevalence of this otherwise common complication. As our understanding of the mechanisms that underlie growth impairment advance, so too should the opportunity for developing further novel and targeted therapies.

Activation of an IL-6:STAT3-dependent transcriptome in pediatric-onset inflammatory bowel disease

BACKGROUND

While activation of the IL-6-dependent transcription factor signal transducer and activator of transcription 3 (STAT3) has been implicated in the pathogenesis of inflammatory bowel disease (IBD), a direct effect on mucosal gene expression and inflammation has not been shown. We hypothesized that a proinflammatory IL-6:STAT3-dependent biological network would be up regulated in pediatric-onset IBD patients, and would be associated with the severity of mucosal inflammation.

METHODS

Patients with pediatric-onset IBD were enrolled at diagnosis and during therapy. Serum cytokine analysis was performed using Bioplex. STAT3 phosphorylation (pSTAT3) in peripheral blood leukocytes (PBLs) was assessed by flow cytometry. Immunohistochemistry of colonic mucosa was used to localize pSTAT3 and STAT3 target genes. Microarray analysis was used to determine RNA expression profiles from colon biopsies.

RESULTS

Circulating IL-6 was upregulated in active IBD patients at diagnosis and during therapy. STAT3 activation was increased in PB granulocytes, IL-6-stimulated CD3(+)/CD4(+) lymphocytes, and affected colon biopsies of IBD patients. The frequency of pSTAT3+ PB granulocytes and colon epithelial and lamina propria cells was highly correlated with the degree of mucosal inflammation. Microarray and Ingenuity Systems bioinformatics analysis identified IL-6:STAT3-dependent biological networks upregulated in IBD patients which control leukocyte recruitment, HLA expression, angiogenesis, and tissue remodeling.

CONCLUSIONS

A proinflammatory IL6:STAT3 biologic network is upregulated in active pediatric IBD patients at diagnosis and during therapy. Specific targeting of this network may be effective in reducing mucosal inflammation.

Serum biomarkers in a mouse model of bacterial-induced inflammatory bowel disease

BACKGROUND

The diagnosis and classification of inflammatory bowel disease (IBD) require both clinical and histopathologic data. Serum biomarkers would be of considerable benefit to noninvasively monitor the progression of disease, assess effectiveness of therapies, and assist in understanding disease pathogenesis. Currently, there are limited noninvasive biomarkers for monitoring disease progression in animal IBD models, which are used extensively to develop new therapies and to understand IBD pathogenesis.

METHODS

Serum biomarkers of early and late IBD were identified using multianalyte profiling in mdr1a(-/-) mice with IBD triggered by infection with Helicobacter bilis. The correlation of changes in these biomarkers with histopathology scores and clinical signs in the presence and in the absence of antibiotic treatment was determined.

RESULTS

Serum levels of interleukin (IL)-11, IL-17, 10-kDa interferon-gamma-inducible protein (IP-10), lymphotactin, monocyte chemoattractant protein (MCP)-1, and vascular cell adhesion molecule (VCAM)-1 were elevated early in IBD. In late, more severe IBD, serum levels of IL-11, IP-10, haptoglobin, matrix metalloproteinase-9, macrophage inflammatory protein (MIP)-1gamma, fibrinogen, immunoglobulin A, MIP-3 beta (beta), VCAM-1, apolipoprotein (Apo) A1, and IL-18 were elevated. All late serum biomarkers except Apo A1 correlated with histopathology scores. Antibiotic treatment improved clinical signs of IBD and decreased mean serum values of many of the biomarkers. For all biomarkers, the individual pathology scores correlated significantly with individual serum analyte levels after treatment.

CONCLUSIONS

Serum analyte measurement is a useful, noninvasive method for monitoring disease in a mouse model of bacterial-induced IBD.

Impaired intestinal iron absorption in Crohn's disease correlates with disease activity and markers of inflammation

BACKGROUND

Anemia in patients with Crohn's disease (CD) is a common problem of multifactorial origin, including blood loss, malabsorption of iron, and anemia of inflammation. Anemia of inflammation is caused by the effects of inflammatory cytokines [predominantly interleukin-6 (IL-6)] on iron transport in enterocytes and macrophages. We sought to elucidate alterations in iron absorption in pediatric patients with active and inactive CD.

METHODS

Nineteen subjects with CD (8 female, 11 male patients) were recruited between April 2003 and June 2004. After an overnight fast, serum iron and hemoglobin levels, serum markers of inflammation [IL-6, C-reactive protein (CRP), and erythrocyte sedimentation rate], and a urine sample for hepcidin assay were obtained at 8 am. Ferrous sulfate (1 mg/kg) was administered orally, followed by determination of serum iron concentrations hourly for 4 hours after the ingestion of iron. An area under the curve for iron absorption was calculated for each patient data set.

RESULTS

There was a strong inverse correlation between the area under the curve and IL-6 (P = 0.002) and area under the curve and CRP levels (P = 0.04). Similarly, the difference between baseline and 2-hour serum iron level (Delta[Fe]2hr) correlated with IL-6 (P = 0.008) and CRP (P = 0.045). When cutoff values for IL-6 (>5 pg/mL) and CRP (>1.0 mg/dL) were used, urine hepcidin levels also positively correlated with IL-6 and CRP levels (P = 0.003 and 0.007, respectively).

CONCLUSIONS

Subjects with active CD have impaired oral iron absorption and elevated IL-6 levels compared with subjects with inactive disease. These findings suggest that oral iron may be of limited benefit to these patients. Future study is needed to define the molecular basis for impaired iron absorption.

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.

Lamina propria and circulating interleukin-6 in newly diagnosed pediatric inflammatory bowel disease patients

OBJECTIVES

Understanding cytokine production patterns in early mucosal lesions of pediatric patients newly diagnosed with inflammatory bowel disease (IBD) may be critical to understanding IBD pathogenesis. Interleukin-6 (IL-6) has a central role in a multitude of immune system reactions; however, inconsistent lamina propria and serum IL-6 has been reported in IBD patients. Newly diagnosed pediatric IBD patients have not previously been evaluated for lamina propria or serum IL-6.

METHODS

Serum and intestinal lamina propria biopsy whole organ culture supernatants were evaluated by ELISA for IL-6 obtained from newly diagnosed IBD patients, before initiation of immunomodulatory therapies.

RESULTS

Levels of lamina propria IL-6 demonstrated significant correlation with graded severity of histological inflammation (p < 0.001). Log-transformed serum and organ culture IL-6 levels demonstrated significant correlation (p < 0.0001, R2 = 0.6226). Assigning a demarcation level of >400 pg/ml, serum IL-6 concentrations were a superior marker for the presence of microscopic intestinal inflammation than erythrocyte sedimentation rate (ESR), with a sensitivity of 82%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 82%. When evaluating subtypes of IBD, serum IL-6 levels were correlated more significantly with active disease in ulcerative colitis patients (p = 0.01, R2 = 0.74) than in Crohn's disease patients (p = 0.21, R2 = 0.33).

CONCLUSIONS

This study outlines graded production of IL-6 in intestinal lamina propria and serum of newly diagnosed pediatric IBD patients, confirming the presence of IL-6 in early IBD patients. In addition, serum IL-6 may be a good predictor of IBD in pediatric patients with suspected or newly diagnosed IBD.

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.

Etiopathogenesis of inflammatory bowel disease: the importance of the pediatric perspective

Inflammatory bowel disease (IBD) is now recognized as a common chronic disease affecting children and adolescents. This article will review recent advances made in the fields of genetics, epidemiology, gut ecology, and immunology regarding the etiopathogenesis of IBD, with particular emphasis on the contributions made by pediatric studies. Areas where further study of the pediatric age group would be beneficial will be highlighted.

Proliferative response of different human osteoblast-like cell models to proinflammatory cytokines

Children with inflammatory bowel disease are known to be at risk of osteopenia. The cause of this osteopenia is likely to be multifactorial, but the inflammatory process with its characteristic overproduction of cytokines has been implicated. To investigate this possible contribution of the disease activity to the development of osteopenia, we performed in vitro assays of the proliferation of osteoblast-like cells of differing origins in response to the inflammatory cytokines tumor necrosis factor-alpha and IL-1/beta. Osteoblast-like cells derived from pediatric bone explants, adherent stromal cells derived from bone marrow (osteoprogenitors), MG-63 osteosarcoma cells, and SV-40 virally transformed osteoprogenitor cells (HCC1) were studied. Tumor necrosis factor-alpha stimulated the proliferation of cells in primary cultures (i.e. from explants and marrow samples) in a linear, dose-dependent manner. In contrast, inhibition of proliferation was observed with the established cell lines (MG-63 and HCC1). IL-1beta stimulated proliferation of all cells apart from the immortalized human bone marrow cell line, HCC1, in which case potent inhibition was observed. We conclude that proinflammatory cytokines are potent regulators of osteoblast-like cell proliferation, and that the responses are specific to cell type. The opposite results obtained with established cell lines compared with the primary cultures suggest that careful consideration should be given to choosing the most suitable cell line for in vitro studies relating to in vivo mechanisms predisposing to osteopenia.

Platelet number and interleukin-6 correlate with VEGF but not with bFGF serum levels of advanced cancer patients

We have compared the platelet number and the serum concentration of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and interleukin-6 (IL-6) in 80 blood samples of 50 patients with advanced cancer. We have also measured the mitogenic effect of patient sera on endothelial cells in vitro in order to estimate the biological activity of serum VEGF. Serum VEGF concentration correlated with platelet number (r = 0.61; P < 10(-4)). Serum IL-6 levels correlated with platelet count (r = 0.36; P < 10(-3)), with serum VEGF levels (r = 0.55; P < 10(-4)) and with the calculated load of VEGF per platelet (r = 0.4; P = 3 x 10(-4)). Patients with thrombocytosis had a median VEGF serum concentration which was 3.2 times higher (P < 10(-4)) and a median IL-6 serum level which was 5.8 times higher (P = 0.03) than in other patients. Serum bFGF did not show an association with any of the other parameters. Patient sera with high VEGF and bFGF content stimulated endothelial cell proliferation significantly more than other sera (P = 4 x 10(-3)). These results support the role of platelets in the storage of biologically active VEGF. Platelets seem to prevent circulating VEGF from inducing the development of new blood vessels except at sites where coagulation takes place. IL-6, besides its thrombopoietic effect, also seems to affect the amount of VEGF stored in the platelets. This is in accordance with the indirect angiogenic action of IL-6 reported previously. The interaction of IL-6 with the angiogenic pathways in cancer might explain the stimulation of tumour growth occasionally observed during IL-6 administration. It also conforms to the worse outcome associated with high IL-6 levels and with thrombocytosis in several tumour types and benign angiogenic diseases.

Femoral neck osteopenia in patients with inflammatory bowel disease

OBJECTIVE

The mechanism of bone loss in patients with inflammatory bowel disease (IBD) is not completely understood. The aim of this study was to assess indices of bone turnover and bone mineral density (BMD) in the lumbar spine and femoral neck in IBD patients.

METHODS

Sixty-three patients with Crohn's disease and 41 with ulcerative colitis were studied. Serum bone-specific alkaline phosphatase (B-ALP), osteocalcin, parathyroid hormone (PTH), 25 hydroxyvitamin D, interleukin-6 (IL-6), and urinary N-telopeptide cross linked type 1 collagen (NTX) were determined. BMD of the lumbar spine and femoral neck was determined by dual x-ray absorptiometry in 59 patients.

RESULTS

In the femoral neck 42% of the patients had osteopenia (-2.5 SD < BMD T score < -1 SD) and another 41% had osteoporosis (BMD T score < -2.5). In the spine 34% of the patients had osteopenia and additional 42% had osteoporosis. BMD T scores were lower in the femoral neck compared to the spine. Reduced BMD was unrelated to gender, disease type, lifetime corticosteroid dose, but inversely correlated with disease duration (r = -0.36, p < 0.05). Serum IL-6 was higher in IBD patients compared to controls. A reduced level of osteocalcin, a marker of bone formation, was present in 7% of patients and an increase in NTX, a marker of bone resorption, in 25% of them. Osteoporotic IBD patients (spine or hip BMD T score < -2.5) had increased serum IL-6, osteocalcin and PTH level compared to nonosteoporotic patients.

CONCLUSIONS

There is a high prevalence of reduced BMD at the spine and femoral neck in IBD patients, which is more severe in the hip. Bone turnover in osteoporotic IBD patients is associated with an increase in osteocalcin, PTH and IL-6. IL-6 may play a role in the pathogenesis of bone loss in IBD.

Serum leptin in children and young adults with inflammatory bowel disease

BACKGROUND

Pediatric inflammatory bowel disease is often associated with growth failure and inadequate energy intake. Although several circulating cytokines are known to be elevated in inflammatory bowel disease, the mechanism for the related anorexia has not been described. Leptin is a newly recognized circulating protein that is an important regulator of appetite and energy metabolism; leptin levels are elevated in several animal models of inflammation. This study was conducted to determine whether serum leptin levels are elevated in young patients with inflammatory bowel disease.

METHODS

One hundred twelve children and young adults with Crohn's disease or ulcerative colitis were studied prospectively. Forty-two patients with other gastrointestinal illnesses were used as control subjects. Height, weight, erythrocyte sedimentation rate, serum albumin concentration, and clinical information were collected prospectively, and leptin was measured by radioimmunoassay of stored serum.

RESULTS

No significant differences in leptin levels were found among disease groups or control subjects. Body mass index and gender were the only independent predictors of serum leptin in all groups examined. Disease activity varied inversely with serum leptin in patients with Crohn's disease, but these differences were explained entirely by variations in body mass index.

CONCLUSIONS

The determinants of serum leptin were the same in young patients with inflammatory bowel disease as in normal populations, indicating that alterations in leptin levels are unlikely to mediate the anorexia and growth failure associated with this disease.