Nutrition as primary therapy in pediatric Crohn's disease: fact or fantasy?
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Child↗
Biomedical subjects
E G Seidman
Publications and source records attributed to E G Seidman.
Diagnostic markers of inflammatory bowel disease.
The diagnosis of inflammatory bowel disease is usually straightforward, based on a detailed history and physical examination, along with standard radiographic and endoscopic investigations, biopsies, and laboratory parameters. More challenging is the search for clinically useful, noninvasive markers for Crohn disease and ulcerative colitis to accurately screen cases with nonspecific and indolent symptoms. Equally required are diagnostic markers that discriminate between these two disorders in cases with indeterminate colitis. Another dilemma for clinicians is that there are no simple measures to observe disease activity and predict relapses. This review describes the recent advances in diagnostic markers that afford the ability to screen for inflammatory bowel disease, discriminate between its types, and monitor disease activity. These include serological, fecal, and tissue markers; permeability tests; and diagnostic imaging using color Doppler ultrasonography.
Journal Article↗
Pneumatosis intestinalis and colocolic intussusception complicating Crohn's disease.
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Anti-Inflammatory Agents↗
Doppler US in patients with crohn disease: vessel density in the diseased bowel reflects disease activity.
PURPOSE: To determine if neovascularization associated with Crohn disease, as detected with Doppler ultrasonography (US), reflects clinical disease activity. MATERIALS AND METHODS: A devised measurement, vessel density, was estimated with color Doppler US. Patients with Crohn disease underwent clinical and laboratory assessment in which the Crohn disease activity index was measured; patients underwent abdominal US the same week. Color Doppler US was performed by using a 7.5-10.0- or 8.0-12.0-MHz transducer, the lowest possible pulse repetition frequency without aliasing, a low wall filter, and high Doppler gain settings. The length and thickness of the affected loops were measured, and the number of color Doppler signals per square centimeter in the bowel loop was counted. Pulsed Doppler US was used to confirm that the signals originated from arteries or veins and not from movement artifacts. RESULTS: Ninety-two patients (aged 7-20 years; mean, 14.85 years; 44 female, 48 male) underwent 119 examinations; 85 were performed in patients with active disease. Affected loops were thicker (10.6 vs 4. 6 mm; P: <.001) and had a higher vessel density with disease (69 of 119 examinations) than during remission (two of 34 examinations; P: <.001). CONCLUSION: Vessel density in affected bowel loops, as estimated with Doppler US, and bowel wall thickness (>5 mm) reflect disease activity in patients with Crohn disease.
Adolescent↗
Caco-2 cells and human fetal colon: a comparative analysis of their lipid transport.
Caco-2 cells and human colonic explants were compared for their ability to esterify lipid classes, synthesize apolipoproteins and assemble lipoproteins. Highly differentiated cells and colonic explants were incubated with [(14)C]oleic acid or [(35)S]methionine for 48 h. Caco-2 cells demonstrated a higher ability to incorporate [(14)C]oleic acid into cellular phospholipids (13-fold, P<0.005), triglycerides (28-fold, P<0.005) and cholesteryl ester (2-fold, P<0. 01). However, their medium/cell lipid ratio was 11 times lower, indicating a limited capacity to export newly synthesized lipids. De novo synthesis of apo B-48 and apo B-100 was markedly increased (7%0 and 240%, respectively), whereas the biogenesis of apo A-I was decreased (60%) in Caco-2 cells. The calculated apo B-48/apo B-100 ratio was substantially diminished (107%), suggesting less efficient mRNA editing in Caco-2 cells. When lipoprotein distribution was examined, it displayed a prevalence of VLDL and LDL, accompanied along with a lower proportion of chylomicron and HDL. In addition, differences in lipoprotein composition were evidenced between colonic explants and Caco-2 cells. Therefore, our findings stress the variance in the magnitude of lipid, apolipoprotein and lipoprotein synthesis and secretion between the two intestinal models. This may be due to various factors, including the origin of Caco-2 cell line, i.e., colon carcinoma.
Apolipoproteins↗
TNFalpha-induced IEC-6 cell apoptosis requires activation of ICE caspases whereas complete inhibition of the caspase cascade leads to necrotic cell death.
Tumor necrosis factor (TNF)alpha is considered to play a key pathogenetic role in inflammatory bowel diseases. In this study we analyzed the mechanisms by which TNFalpha induces intestinal epithelial cell apoptosis. TNFalpha alone, and more potently in combination with IFNgamma, induced a high degree of IEC-6 cell apoptosis. This effect was more than 100-fold stronger if both of the TNF-R were stimulated, compared to stimulation of the p55-TNF-R alone, indicating an important apoptosis enhancing effect of the p75-TNF-R. TNFalpha-induced apoptosis required activation of ICE caspases and was completely abolished by its inhibitor, zVAD-fmk. Specific inhibition of caspase-3 with zDEVD-fmk did not alter the effect of TNFalpha. Western blot analyses confirmed that caspase-3 was not activated in response to TNFalpha. In the presence of complete inhibition of the caspase cascade with zVAD-fmk (>/=50 microM), TNFalpha induced cell necrosis rather than apoptosis. Our data reveal that TNFalpha can trigger enterocyte cell death via apoptosis or necrosis, depending upon the activation or blockade of specific caspases.
Amino Acid Chloromethyl Ketones↗
Susceptibility to FAS-induced apoptosis in human nontumoral enterocytes: role of costimulatory factors.
FAS-FAS ligand interaction has been implicated in increased enterocyte apoptosis seen in immune-mediated bowel injury. However, scant information exists on the role of FAS in physiological enterocyte turnover. In the present study, the regulation of enterocyte FAS and FAS ligand expression by cytokines and its functional role in human intestinal epithelial cell apoptosis and proliferation were analyzed with two different models: a nontransformed human intestinal epithelial cell line (HIEC) and normal colonic explant cultures. HIEC constitutively expressed FAS, as analyzed by flow cytometry. However, stimulation with agonistic anti-FAS antibody (1-500 ng/ml) did not induce HIEC apoptosis. In contrast, in the presence of tumor necrosis factor alpha (TNFalpha) and/or interferon gamma (IFNgamma), HIEC became highly susceptible to FAS-induced apoptosis. The sensitizing effect to FAS-induced apoptosis was mediated via TNFalpha- and IFNgamma-induced upregulation of FAS expression (maximally 348%). Receptor studies showed that the effect of TNFalpha on FAS was mediated via the p55 TNF receptor. In colonic organ cultures, IFNgamma and TNFalpha also enhanced colonocyte FAS expression, resulting in a markedly increased apoptotic response to stimulation of this receptor, as shown by in situ terminal deosyuridine triphosphate nick-end staining. Neither FAS ligand expression nor its induction by cytokines was observed in HIEC or colonic explants. Proliferation studies showed that FAS is not implicated in regulating HIEC growth. These findings suggest that, despite the fact that normal human enterocytes express FAS, costimulatory factors, such as TNFalpha or IFNgamma, abundantly secreted under inflammatory conditions, are necessary to sensitize intestinal epithelial cells to FAS-induced apoptosis by upregulating this receptor.
Antigens, CD↗
Butyrate mediates Caco-2 cell apoptosis via up-regulation of pro-apoptotic BAK and inducing caspase-3 mediated cleavage of poly-(ADP-ribose) polymerase (PARP).
Butyrate exerts potent anti-tumor effects by inhibiting cancer cell growth and inducing apoptosis. However, the molecular mechanisms mediating these effects remain largely unknown. Using the Caco-2 cell line, a well established model of colon cancer cells, our data show that butyrate induced apoptosis (maximum 79%) is mediated via activation of the caspase-cascade. A key event was the proteolytic activation of caspase-3, triggering degradation of poly-(ADP-ribose) polymerase (PARP). Inactivation of caspase-3 with the tetrapeptide zDEVD-FMK completely inhibited the apoptotic response to butyrate. In parallel, butyrate potently up-regulated the expression of the pro-apoptotic protein bak, without changing Caco-2 cell bcl-2 expression. Butyrate-induced Caco-2 cell apoptosis was completely blocked by the addition of cycloheximide, indicating the necessity of protein synthesis. However, when this inhibitor was added at a time point where bak expression was already enhanced (12 - 16 h after butyrate stimulation), it failed to protect Caco-2 cells against apoptosis. Taken together, these data provide evidence that the molecular events involved in butyrate induced colon cancer cell apoptosis include the caspase-cascade and the mitochondrial bcl-pathway.
Apoptosis↗
Dexamethasone inhibits IFNgamma-induced MHC class II expression of intestinal epithelial cells independently of the TGF-beta1 regulatory pathway.
BACKGROUND: In the presence of inflammation, an increased expression of enterocyte MHC class II is observed, leading to altered mucosal antigen handling. Corticosteroids are potent anti-inflammatory drugs, widely used in treating inflammatory bowel disorders. However, their diverse mechanisms of action are only partially understood. AIM: To evaluate effect and mechanisms of corticosteroids on intestinal crypt epithelial cell MHC class II. METHODS: The effect of dexamethasone treatment on cytokine-induced MHC class II expression was measured in IEC-6 cells by immunofluorescence and flow cytometry. To determine the role of the TGF-beta1 regulatory pathway in mediating the effects of dexamethasone, neutralizing anti-TGF-beta antibodies were used. Additionally, endogenous and dexamethasone-stimulated IEC-6 cell TGF-beta1 production was measured by ELISA. RESULTS: Dexamethasone potently down-regulated IFNgamma-induced class II expression on IEC-6 cells, in a dose-dependent manner. TGF-beta1 had a similar inhibitory effect on class II expression. However, neutralizing anti-TGF-beta antibodies did not alter the effect of dexamethasone. Furthermore, dexamethasone reduced endogenous TGF-beta1 synthesis. CONCLUSIONS: Corticosteroids inhibit cytokine-induced MHC class II expression on IEC-6 cells in a TGF-beta1 independent way. This effect may markedly alter enterocytic antigen presentation, reducing the aberrant state of activation of mucosal immune cells.
Cells, Cultured↗
Inflammatory bowel disease in pediatric patients.
The management of inflammatory bowel disease in children remains a major challenge to patients, their families, and the health care team. This review highlights the past year's advances concerning epidemiologic studies, new diagnostic considerations, and novel therapeutic approaches. Epidemiologic studies confirmed that Crohn's disease is being increasingly diagnosed in children, whereas the incidence of ulcerative colitis has remained stable. African-American children are as likely to have inflammatory bowel disease as other children. Serologic assays specific for Crohn's disease and ulcerative colitis can assist clinicians in screening for inflammatory bowel disease, as well as discriminating between the two diseases. Studies have revealed that osteopenia and antioxidant vitamin deficiency are common and require screening in pediatric inflammatory bowel disease. Increasing experience with immunosuppressive drugs (6-mercaptopurine, azathioprine) point to their efficacy and generally good toxicity profile in pediatric patients.
Journal Article↗
Autoimmunity with immunodeficiency: a logical paradox.
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Animals↗
Novel immunosuppressive therapies for intestinal and hepatic diseases.
Recent advances in the understanding of the pathogenesis of immune-mediated hepatic and intestinal diseases have led to major therapeutic advances. The introduction of genetically engineered biologic agents specifically designed to target inflammatory mediators responsible for the perpetuation of chronic inflammatory processes is a novel example. Although corticosteroids remain important as a first-line therapeutic option for active inflammatory bowel disease, approximately one third and one fifth of patients develop steroid dependence and resistance, respectively. From a pediatric perspective, a major advance has thus been the advocation of prolonged immunosuppressive therapy with 6-mercaptopurine or azathioprine for children with inflammatory bowel disease. The introduction of effective steroid-sparing agents for the induction and maintenance of remission is a key management issue. The past year has also witnessed the increased utilization of powerful immunosuppressive agents with rapid onset of action, such as cyclosporine and tacrolimus, in patients resistant to conventional therapies. This review will afford pediatricians a sense of what to expect for the management of hepatic and intestinal disorders with immunosuppression as we advance into the new millenium.
Antimetabolites↗
Immunopathogenesis of inflammatory bowel disease: role of cytokines and immune cell-enterocyte interactions.
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Animals↗
Endogenous lipase activity in Caco-2 cells.
Dietary triglycerides, the major precursors of long chain fatty acids (FA), require hydrolysis by pancreatic enzymes prior to their absorption by the small intestine. Although Caco-2 cells are frequently employed for the study of enterocyte lipid metabolism, the presence of an endogenous lipase activity has never been previously reported. The major goal of this investigation was to determine the presence of endogenous Caco-2 cell lipase activity, to examine its capacity to hydrolyze triglycerides, and to define its intracellular location. Caco-2 cells were found to have an endogenous lipase activity, capable of hydrolyzing [1-14C]triolein from the apical cell compartment. A time and concentration dependence of lipase activity was observed, with hydrolysis of triolein into free fatty acids and monoglyceride. The majority of the lipase activity was found in the cytosolic cell fraction and, to a lesser extent, in the apical brush border membrane and other organelles. Protamine sulfate markedly reduced the Caco-2 cell lipase activity, yet it remained relatively insensitive to high concentrations of NaCl, taurocholate, calcium, heparin and chloroquine. The addition of exogenous human gastric lipase to the medium of the apical compartment resulted in a significant increased rate of hydrolysis of triolein, followed by enhanced Caco-2 cell fatty acid uptake and basolateral lipid secretion. The major esterified intracellular lipids were triglycerides and phospholipids. We conclude that Caco-2 cells possess an endogenous lipase capable of hydrolyzing cytosolic triglycerides. Furthermore, activity present on the apical membrane and secreted into the apical medium, though quantitatively less important than the cytosolic lipase, may permit an additional route for energy uptake. The addition of gastric lipase to the Caco-2 cell cultures greatly enhanced FA uptake above that seen with the endogenous lipase alone.
Caco-2 Cells↗
Tyrosine kinase and MAPK inhibition of TNF-alpha- and EGF-stimulated IEC-6 cell growth.
The role of TNF-alpha in modulating intestinal crypt cell growth was examined, in comparison with EGF. Both significantly increased IEC-6 cell proliferation. Neither EGF nor TNF-alpha overcame the inhibitory effect on growth exerted by the tyrosine kinase inhibitor genistein. Immunoblots with phosphotyrosine antibodies showed increased tyrosine phosphorylation of IEC-6 cell proteins in response to EGF and TNF-alpha stimulation. TNF-alpha increased ERK1 and ERK2 MAPK phosphorylation. A MAPK assay confirmed the increased activity upon TNF-alpha stimulation. Selective inhibition of MAPK activation by PD98059 resulted in a dose dependent inhibition of TNF-alpha or EGF-induced IEC-6 cell growth. These findings suggest a role for TNF-alpha in the regulation of intestinal epithelial cell growth and that the mitogenic effect of TNF-alpha requires protein tyrosine phosphorylation and MAPK activation.
Animals↗
Effects of interferon gamma on growth, apoptosis, and MHC class II expression of immature rat intestinal crypt (IEC-6) cells.
Intestinal epithelial cells and the mucosal immune cells in close proximity are thought to interact very closely. One well-established mechanism of this intercellular cross-talk is via the production of cytokines such as interferon gamma (IFNgamma). The aim of this study was to analyze the effects of IFNgamma on intestinal crypt epithelial cells. IEC-6 cells were cultured in the presence or absence of IFNgamma to measure its effects on proliferation, cell cycle, apoptosis, and major histocompatibility complex (MHC) class II antigen expression. Even at very low doses (0.01 U/ml), IFNgamma significantly inhibited IEC-6 cell proliferation, as demonstrated by reduced 3H-thymidine uptake, stable cell count, and complete arrest in the quiescent G0/G1 phase of the cell cycle. Incubation with supraphysiological doses of IFNgamma (100-1,000 U/ml) did not induce apoptosis, as assessed by morphology and the TUNEL assay. IFNgamma significantly induced de novo IEC-6 class II antigen expression. Tumor necrosis factor alpha (TNF alpha), which alone had no effect, synergistically enhanced this effect of IFNgamma. MHC class II antigen expression was observed to be independent of cell cycle phase. Our results indicate that IFNgamma alters immature crypt epithelial cell turnover and upregulates MHC class II expression. These alterations may be important in the pathogenesis of immune-mediated bowel disorders.
Animals↗
Interpretation of bone mineral density values in pediatric Crohn's disease.
Patients with Crohn's disease (CD) often have low bone mineral density (BMD) for their chronological age (CA). However, pediatric cases frequently have growth failure and delayed bone age (BA) and height age (HA). Do they really have the amount of osteoporosis as measured by BMD and calculated for their CA? The aim was to compare z-scores for BMD in relation to CA and z-scores corrected for BA or height age in pediatric patients. A group of 43 pediatric patients (mean age, 12 years; 14 girls, 29 boys) with CD in remission, prospectively had BMD (measured by dual energy x-ray absorptiometry) and BA. Abnormally low z-score for BMD (below 2 standard deviation [SD] for CA was found in 19 patients (44%). Among these, 9 patients (21% overall) had a BA of more than 2 SD lower than their CA and 12 had height age at least 2 years below CA. When the BMD z-score in these patients was corrected for their BA and height age, 6 of 9 and 8 of 12 patients had a normal BMD. In conclusion, when corrected for BA or CA delay, BMD was abnormal in 26 to 30% rather than 44% of cases. Correct assessment of BMD in Crohn's disease patients with bone age delay requires interpretation in terms of BA or HA, rather than CA.
Absorptiometry, Photon↗
Diagnostic accuracy of serological assays in pediatric inflammatory bowel disease.
BACKGROUND & AIMS: Accurate serological assays are desirable for the diagnosis of inflammatory bowel disease (IBD) types in the pediatric age group. The aim of this study was to test the diagnostic accuracy of modified assays for perinuclear (p) antineutrophil cytoplasmic antibodies (ANCAs) and anti-Saccharomyces cerevisiae antibodies (ASCAs) in patients with pediatric ulcerative colitis (UC) and Crohn's disease (CD) and in those without IBD. METHODS: With observers blinded to patients' diagnoses, serum specimens were analyzed for immunoglobulin (Ig) A and IgG ASCAs and ANCAs by enzyme-linked immunosorbent assay. The perinuclear location of ANCAs visualized by indirect immunofluorescence was confirmed by its disappearance after administration of deoxyribonuclease. RESULTS: IgA and IgG ASCA titers were significantly greater and highly specific for CD (95% for either, 100% if both positive). pANCA was 92% specific for UC and absent in all non-IBD controls. The majority of patients with CD positive for pANCA had a UC-like presentation. Disease location, duration, activity, complications, and treatment with immunosuppressive drugs did not have an impact on the ASCA or pANCA assay results. After resection, UC patients remained pANCA positive, in contrast to patients with CD, in whom ASCA titers decreased toward normal values postoperatively. CONCLUSIONS: ASCA and pANCA assays are highly disease specific for CD and UC, respectively. These serological tests can assist clinicians in diagnosing and categorizing patients with IBD and may be useful in making therapeutic decisions.
Adolescent↗